A Ground-Based Profiling Differential Absorption LIDAR System for Measuring CO2 in the Planetary Boundary Layer

NASA Technical Reports Server (NTRS)

Andrews, Arlyn E.; Burris, John F.; Abshire, James B.; Krainak, Michael A.; Riris, Haris; Sun, Xiao-Li; Collatz, G. James

2002-01-01

Ground-based LIDAR observations can potentially provide continuous profiles of CO2 through the planetary boundary layer and into the free troposphere. We will present initial atmospheric measurements from a prototype system that is based on components developed by the telecommunications industry. Preliminary measurements and instrument performance calculations indicate that an optimized differential absorption LIDAR (DIAL) system will be capable of providing continuous hourly averaged profiles with 250m vertical resolution and better than 1 ppm precision at 1 km. Precision increases (decreases) at lower (higher) altitudes and is directly proportional to altitude resolution and acquisition time. Thus, precision can be improved if temporal or vertical resolution is sacrificed. Our approach measures absorption by CO2 of pulsed laser light at 1.6 microns backscattered from atmospheric aerosols. Aerosol concentrations in the planetary boundary layer are relatively high and are expected to provide adequate signal returns for the desired resolution. The long-term goal of the project is to develop a rugged, autonomous system using only commercially available components that can be replicated inexpensively for deployment in a monitoring network.

Column CO2 Measurement From an Airborne Solid-State Double-Pulsed 2-Micron Integrated Path Differential Absorption Lidar

NASA Technical Reports Server (NTRS)

Singh, U. N.; Yu, J.; Petros, M.; Refaat, T. F.; Remus, R.; Fay, J.; Reithmaier, K.

2014-01-01

NASA LaRC is developing and integrating a double-Pulsed 2-micron direct detection IPDA lidar for CO2 column measurement from an airborne platform. The presentation will describe the development of the 2-micrometers IPDA lidar system and present the airborne measurement of column CO2 and will compare to in-situ measurement for various ground target of different reflectivity.

Ground-based DIAL and IPDA Systems for Remote Sensing of CO2, CH4, and H2O near 1.6 µm

NASA Astrophysics Data System (ADS)

Wagner, G. A.; Plusquellic, D. F.

2017-12-01

Integrated path differential absorption (IPDA) and differential absorption LIDAR (DIAL) are well established methods to monitor atmospheric constituents. At NIST, IPDA and DIAL systems have been developed as standoff systems and their overall performance has been evaluated through intercomparisons including the traceability to point sensor measurements. The all-fiber IPDA system is based on a low-power (< 13 mW, eye-safe) electro-optic modulated continuous-wave laser to produce 123 frequencies at a scan repetition frequency of 10 kHz.1 The transmitter-receiver system measures backscatter from natural targets and is rastered during the measurements to reduce speckle effects. The receiver consists of a 28 cm telescope, photomultiplier tube, and a streaming data acquisition system for direct photon discrimination and counting. The eye-safe DIAL system is based on an optical parametric oscillator2,3 that operates at a pulse repetition frequency of 100 Hz and alternates between on-line and off-line frequencies with pulse energies of < 10 mJ/pulse. The receivers consist of two telescopes (near field: 28 cm; far field: 40 cm), photomultiplier tubes, and a 2 GS/s hybrid data acquisition system for photon counting and current detection. We demonstrate the performance of the DIAL and IPDA systems and present results of a CO2 IPDA/DIAL/point sensor traceability study performed in Boulder (CO, USA) in summer 2017. 1. G. A. Wagner and D. F. Plusquellic, "Ground-Based, Integrated Path Differential Absorption LIDAR Measurement of CO2, CH4 and H2O near 1.6 µm," Applied Optics, 55(23), 6292-6310 (2016). 2. D. J. Armstrong, and A. V. Smith, "150-mJ 1550-nm KTA OPO with Good Beam Quality and High Efficiency," SPIE, 5337, 71-80 (2004). 3. K. O. Douglass, S. E. Maxwell, D. F. Plusquellic, J. T. Hodges, R. D. van Zee, D. V. Samarov, J. R. Whetstone, "Construction of a High Power OPO Laser System for Differential Absorption LIDAR," SPIE, 8159, 81590D (2011).

Resonant tube for measurement of sound absorption in gases at low frequency/pressure ratios

NASA Technical Reports Server (NTRS)

Zuckerwar, A. J.; Griffin, W. A.

1980-01-01

The paper describes a resonant tube for measuring sound absorption in gases, with specific emphasis on the vibrational relaxation peak of N2, over a range of frequency/pressure ratios from 0.1 to 2500 Hz/atm. The experimental background losses measured in argon agree with the theoretical wall losses except at few isolated frequencies. Rigid cavity terminations, external excitation, and a differential technique of background evaluation were used to minimize spurious contributions to the background losses. Room temperature measurements of sound absorption in binary mixtures of N2-CO2 in which both components are excitable resulted in the maximum frequency/pressure ratio in Hz/atm of 0.063 + 123m for the N2 vibrational relaxation peak, where m is mole percent of added CO2; the maximum ratio for the CO2 peak was 34,500 268m where m is mole percent of added N2.

First measurements of a carbon dioxide plume from an industrial source using a ground based mobile differential absorption lidar.

PubMed

Robinson, R A; Gardiner, T D; Innocenti, F; Finlayson, A; Woods, P T; Few, J F M

2014-08-01

The emission of carbon dioxide (CO2) from industrial sources is one of the main anthropogenic contributors to the greenhouse effect. Direct remote sensing of CO2 emissions using optical methods offers the potential for the identification and quantification of CO2 emissions. We report the development and demonstration of a ground based mobile differential absorption lidar (DIAL) able to measure the mass emission rate of CO2 in the plume from a power station. To our knowledge DIAL has not previously been successfully applied to the measurement of emission plumes of CO2 from industrial sources. A significant challenge in observing industrial CO2 emission plumes is the ability to discriminate and observe localised concentrations of CO2 above the locally observed background level. The objectives of the study were to modify our existing mobile infrared DIAL system to enable CO2 measurements and to demonstrate the system at a power plant to assess the feasibility of the technique for the identification and quantification of CO2 emissions. The results of this preliminary study showed very good agreement with the expected emissions calculated by the site. The detection limit obtained from the measurements, however, requires further improvement to provide quantification of smaller emitters of CO2, for example for the detection of fugitive emissions. This study has shown that in principle, remote optical sensing technology will have the potential to provide useful direct data on CO2 mass emission rates.

Double-pulse 2-μm integrated path differential absorption lidar airborne validation for atmospheric carbon dioxide measurement.

PubMed

Refaat, Tamer F; Singh, Upendra N; Yu, Jirong; Petros, Mulugeta; Remus, Ruben; Ismail, Syed

2016-05-20

Field experiments were conducted to test and evaluate the initial atmospheric carbon dioxide (CO₂) measurement capability of airborne, high-energy, double-pulsed, 2-μm integrated path differential absorption (IPDA) lidar. This IPDA was designed, integrated, and operated at the NASA Langley Research Center on-board the NASA B-200 aircraft. The IPDA was tuned to the CO₂ strong absorption line at 2050.9670 nm, which is the optimum for lower tropospheric weighted column measurements. Flights were conducted over land and ocean under different conditions. The first validation experiments of the IPDA for atmospheric CO₂ remote sensing, focusing on low surface reflectivity oceanic surface returns during full day background conditions, are presented. In these experiments, the IPDA measurements were validated by comparison to airborne flask air-sampling measurements conducted by the NOAA Earth System Research Laboratory. IPDA performance modeling was conducted to evaluate measurement sensitivity and bias errors. The IPDA signals and their variation with altitude compare well with predicted model results. In addition, off-off-line testing was conducted, with fixed instrument settings, to evaluate the IPDA systematic and random errors. Analysis shows an altitude-independent differential optical depth offset of 0.0769. Optical depth measurement uncertainty of 0.0918 compares well with the predicted value of 0.0761. IPDA CO₂ column measurement compares well with model-driven, near-simultaneous air-sampling measurements from the NOAA aircraft at different altitudes. With a 10-s shot average, CO₂ differential optical depth measurement of 1.0054±0.0103 was retrieved from a 6-km altitude and a 4-GHz on-line operation. As compared to CO₂ weighted-average column dry-air volume mixing ratio of 404.08 ppm, derived from air sampling, IPDA measurement resulted in a value of 405.22±4.15  ppm with 1.02% uncertainty and 0.28% additional bias. Sensitivity analysis of environmental systematic errors correlates the additional bias to water vapor. IPDA ranging resulted in a measurement uncertainty of <3  m.

Active optical CO2 sensing for Ground-based, Airborne, and from Space platform

NASA Astrophysics Data System (ADS)

Sakaizawa, D.; Kawakami, S.; Nakajima, M.; Tanaka, T.; Miyamoto, Y.; Inoue, M.; Morino, I.; Uchino, O.; Sawa, Y.; Matsueda, H.

2011-12-01

Accurate measurements of lower tropospheric CO2 from space are strongly needed to quantify processes that identify the CO2 flux by the lands and oceans. The Greenhouse gases Observing SATellite (GOSAT) is the first space mission focused on lower tropospheric CO2 measurements by detecting the near-infrared spectral absorption in reflected sunlight. The GOSAT mission is a key first step, and will increase knowledge about atmospheric CO2 distributions. However there are unavoidable limitations imposed by its measurements approach, 1) the best performance of CO2 total column measurements can only be performed under the clear-sky atmosphere, 2) seasonal dependence reduces its global coverage, such as the case of the northern hemisphere in winter, and 3) unknowns and variations in cloud and aerosol contamination is also sensitive for CO2 measurements. The laser-based CO2 remote sensing is advantage of those un-met needs. We have developed and improved a compact differential laser absorption sensor (LAS) for measuring the weighted column-averaged dry CO2 mixing ratio (Wq) as a candidate for space mission. Our instrument employs two continuous-wave lasers and a fiber amplifier, which are available of simultaneous measurements of CO2 differential absorption optical depth and range to the target. The amplitude-modulated laser outputs are amplified by a fiber-amplifier. The receiver uses a compact telescope and photodiodes, and measures the laser powers reflected from the target. The gas absorption and column-averaged mixing ratio for the CO2 are evaluated from the ratio of the on- and off-line signals. We have performed ground-based and airborne measurement to evaluate uncertainty of Wq measurements. In these measurements R(12) line in the (30012<-00001) absorption bands of 12C16O2 was used. The precision of the ground-based measurements of horizontal Wq was 0.49% for a horizontal range of 2.1 km. The first airborne measurements were also made during August 2009. These measurements were made over grasslands from 0.5-7 km altitude. There results were compared with airborne flask sampling data and confirmed same trends along height. In February 2010 and February 2011 we made a total of 6 flights and also measured the vertical Wq over the urban area. A high correlation coefficient of 0.99 was obtained between Wq observed by LAS and that calculated by airborne in-situ measurement. More details about measurements and analysis will be presented in the meeting.

Modeling CO2 mass transfer in amine mixtures: PZ-AMP and PZ-MDEA.

PubMed

Puxty, Graeme; Rowland, Robert

2011-03-15

The most common method of carbon dioxide (CO(2)) capture is the absorption of CO(2) into a falling thin film of an aqueous amine solution. Modeling of mass transfer during CO(2) absorption is an important way to gain insight and understanding about the underlying processes that are occurring. In this work a new software tool has been used to model CO(2) absorption into aqueous piperazine (PZ) and binary mixtures of PZ with 2-amino-2-methyl-1-propanol (AMP) or methyldiethanolamine (MDEA). The tool solves partial differential and simultaneous equations describing diffusion and chemical reaction automatically derived from reactions written using chemical notation. It has been demonstrated that by using reactions that are chemically plausible the mass transfer in binary mixtures can be fully described by combining the chemical reactions and their associated parameters determined for single amines. The observed enhanced mass transfer in binary mixtures can be explained through chemical interactions occurring in the mixture without need to resort to using additional reactions or unusual transport phenomena such as the "shuttle mechanism".

Random-modulation differential absorption lidar based on semiconductor lasers and single photon counting for atmospheric CO2 sensing

NASA Astrophysics Data System (ADS)

Quatrevalet, M.; Ai, X.; Pérez-Serrano, A.; Adamiec, P.; Barbero, J.; Fix, A.; Rarity, J. G.; Ehret, G.; Esquivias, I.

2017-09-01

Carbon dioxide (CO2) is the major anthropogenic greenhouse gas contributing to global warming and climate change. Its concentration has recently reached the 400-ppm mark, representing a more than 40 % increase with respect to its level prior to the industrial revolution.

Optoacoustic measurements of water vapor absorption at selected CO laser wavelengths in the 5-micron region

NASA Technical Reports Server (NTRS)

Menzies, R. T.; Shumate, M. S.

1976-01-01

Measurements of water vapor absorption were taken with a resonant optoacoustical detector (cylindrical pyrex detector, two BaF2 windows fitted into end plates at slight tilt to suppress Fabry-Perot resonances), for lack of confidence in existing spectral tabular data for the 5-7 micron region, as line shapes in the wing regions of water vapor lines are difficult to characterize. The measurements are required for air pollution studies using a CO laser, to find the differential absorption at the wavelengths in question due to atmospheric constituents other than water vapor. The design and performance of the optoacoustical detector are presented. Effects of absorption by ambient NO are considered, and the fixed-frequency discretely tunable CO laser is found suitable for monitoring urban NO concentrations in a fairly dry climate, using the water vapor absorption data obtained in the study.

Pulsed Airborne Lidar Measurements of C02 Column Absorption

NASA Technical Reports Server (NTRS)

Abshire, James B.; Riris, Haris; Allan, Graham R.; Weaver, Clark J.; Mao, Jianping; Sun, Xiaoli; Hasselbrack, William E.; Rodriquez, Michael; Browell, Edward V.

2011-01-01

We report on airborne lidar measurements of atmospheric CO2 column density for an approach being developed as a candidate for NASA's ASCENDS mission. It uses a pulsed dual-wavelength lidar measurement based on the integrated path differential absorption (IPDA) technique. We demonstrated the approach using the CO2 measurement from aircraft in July and August 2009 over four locations. The results show clear CO2 line shape and absorption signals, which follow the expected changes with aircraft altitude from 3 to 13 km. The 2009 measurements have been analyzed in detail and the results show approx.1 ppm random errors for 8-10 km altitudes and approx.30 sec averaging times. Airborne measurements were also made in 2010 with stronger signals and initial analysis shows approx. 0.3 ppm random errors for 80 sec averaging times for measurements at altitudes> 6 km.

High Energy 2-Micron Solid-State Laser Transmitter for NASA's Airborne CO2 Measurements

NASA Technical Reports Server (NTRS)

Singh, Upendra N.; Yu, Jirong; Petros, Mulugeta; Bai, Yingxin

2012-01-01

A 2-micron pulsed, Integrated Path Differential Absorption (IPDA) lidar instrument for ground and airborne atmospheric CO2 concentration measurements via direct detection method is being developed at NASA Langley Research Center. This instrument will provide an alternate approach to measure atmospheric CO2 concentrations with significant advantages. A high energy pulsed approach provides high-precision measurement capability by having high signal-to-noise level and unambiguously eliminates the contamination from aerosols and clouds that can bias the IPDA measurement.

Airborne 2-Micron Double Pulsed Direct Detection IPDA Lidar for Atmospheric CO2 Measurement

NASA Technical Reports Server (NTRS)

Yu, Jirong; Petros, Mulugeta; Refaat, Tamer F.; Reithmaier, Karl; Remus, Ruben; Singh, Upendra; Johnson, Will; Boyer, Charlie; Fay, James; Johnston, Susan;

Assessing Methods for Mapping 2D Field Concentrations of CO2 Over Large Spatial Areas for Monitoring Time Varying Fluctuations

NASA Astrophysics Data System (ADS)

Zaccheo, T. S.; Pernini, T.; Botos, C.; Dobler, J. T.; Blume, N.; Braun, M.; Levine, Z. H.; Pintar, A. L.

2014-12-01

This work presents a methodology for constructing 2D estimates of CO2 field concentrations from integrated open path measurements of CO2 concentrations. It provides a description of the methodology, an assessment based on simulated data and results from preliminary field trials. The Greenhouse gas Laser Imaging Tomography Experiment (GreenLITE) system, currently under development by Exelis and AER, consists of a set of laser-based transceivers and a number of retro-reflectors coupled with a cloud-based compute environment to enable real-time monitoring of integrated CO2 path concentrations, and provides 2D maps of estimated concentrations over an extended area of interest. The GreenLITE transceiver-reflector pairs provide laser absorption spectroscopy (LAS) measurements of differential absorption due to CO2 along intersecting chords within the field of interest. These differential absorption values for the intersecting chords of horizontal path are not only used to construct estimated values of integrated concentration, but also employed in an optimal estimation technique to derive 2D maps of underlying concentration fields. This optimal estimation technique combines these sparse data with in situ measurements of wind speed/direction and an analytic plume model to provide tomographic-like reconstruction of the field of interest. This work provides an assessment of this reconstruction method and preliminary results from the Fall 2014 testing at the Zero Emissions Research and Technology (ZERT) site in Bozeman, Montana. This work is funded in part under the GreenLITE program developed under a cooperative agreement between Exelis and the National Energy and Technology Laboratory (NETL) under the Department of Energy (DOE), contract # DE-FE0012574. Atmospheric and Environmental Research, Inc. is a major partner in this development.

Airborne 2-Micron Double-Pulsed Integrated Path Differential Absorption Lidar for Column CO2 Measurement

NASA Technical Reports Server (NTRS)

Singh, Upendra N.; Yu, Jirong; Petros, Mulugeta; Refaat, Tamer F.; Remus, Ruben G.; Fay, James J.; Reithmaier, Karl

2014-01-01

Double-pulse 2-micron lasers have been demonstrated with energy as high as 600 millijouls and up to 10 Hz repetition rate. The two laser pulses are separated by 200 microseconds and can be tuned and locked separately. Applying double-pulse laser in DIAL system enhances the CO2 measurement capability by increasing the overlap of the sampled volume between the on-line and off-line. To avoid detection complicity, integrated path differential absorption (IPDA) lidar provides higher signal-to-noise ratio measurement compared to conventional range-resolved DIAL. Rather than weak atmospheric scattering returns, IPDA rely on the much stronger hard target returns that is best suited for airborne platforms. In addition, the IPDA technique measures the total integrated column content from the instrument to the hard target but with weighting that can be tuned by the transmitter. Therefore, the transmitter could be tuned to weight the column measurement to the surface for optimum CO2 interaction studies or up to the free troposphere for optimum transport studies. Currently, NASA LaRC is developing and integrating a double-Pulsed 2-micron direct detection IPDA lidar for CO2 column measurement from an airborne platform. The presentation will describe the development of the 2-micron IPDA lidar system and present the airborne measurement of column CO2 and will compare to in-situ measurement for various ground target of different reflectivity.

Towards understanding the variability in biospheric CO2 fluxes: using FTIR spectrometry and a chemical transport model to investigate the sources and sinks of carbonyl sulfide and its link to CO2

NASA Astrophysics Data System (ADS)

Wang, Yuting; Deutscher, Nicholas M.; Palm, Mathias; Warneke, Thorsten; Notholt, Justus; Baker, Ian; Berry, Joe; Suntharalingam, Parvadha; Jones, Nicholas; Mahieu, Emmanuel; Lejeune, Bernard; Hannigan, James; Conway, Stephanie; Mendonca, Joseph; Strong, Kimberly; Campbell, J. Elliott; Wolf, Adam; Kremser, Stefanie

2016-02-01

Understanding carbon dioxide (CO2) biospheric processes is of great importance because the terrestrial exchange drives the seasonal and interannual variability of CO2 in the atmosphere. Atmospheric inversions based on CO2 concentration measurements alone can only determine net biosphere fluxes, but not differentiate between photosynthesis (uptake) and respiration (production). Carbonyl sulfide (OCS) could provide an important additional constraint: it is also taken up by plants during photosynthesis but not emitted during respiration, and therefore is a potential means to differentiate between these processes. Solar absorption Fourier Transform InfraRed (FTIR) spectrometry allows for the retrievals of the atmospheric concentrations of both CO2 and OCS from measured solar absorption spectra. Here, we investigate co-located and quasi-simultaneous FTIR measurements of OCS and CO2 performed at five selected sites located in the Northern Hemisphere. These measurements are compared to simulations of OCS and CO2 using a chemical transport model (GEOS-Chem). The coupled biospheric fluxes of OCS and CO2 from the simple biosphere model (SiB) are used in the study. The CO2 simulation with SiB fluxes agrees with the measurements well, while the OCS simulation reproduced a weaker drawdown than FTIR measurements at selected sites, and a smaller latitudinal gradient in the Northern Hemisphere during growing season when comparing with HIPPO (HIAPER Pole-to-Pole Observations) data spanning both hemispheres. An offset in the timing of the seasonal cycle minimum between SiB simulation and measurements is also seen. Using OCS as a photosynthesis proxy can help to understand how the biospheric processes are reproduced in models and to further understand the carbon cycle in the real world.

A simple method to incorporate water vapor absorption in the 15 microns remote temperature sounding

NASA Technical Reports Server (NTRS)

Dallu, G.; Prabhakara, C.; Conhath, B. J.

1975-01-01

The water vapor absorption in the 15 micron CO2 band, which can affect the remotely sensed temperatures near the surface, are estimated with the help of an empirical method. This method is based on the differential absorption properties of the water vapor in the 11-13 micron window region and does not require a detailed knowledge of the water vapor profile. With this approach Nimbus 4 IRIS radiance measurements are inverted to obtain temperature profiles. These calculated profiles agree with radiosonde data within about 2 C.

Analysis of Vertical Weighting Functions for Lidar Measurements of Atmospheric CO2 and O2

NASA Astrophysics Data System (ADS)

Kooi, S.; Mao, J.; Abshire, J. B.; Browell, E. V.; Weaver, C. J.; Kawa, S. R.

2011-12-01

Several NASA groups have developed integrated path differential absorption (IPDA) lidar approaches to measure atmospheric CO2 concentrations from space as a candidates for NASA's ASCENDS space mission. For example, the Goddard CO2 Sounder approach uses two pulsed lasers to simultaneously measure both CO2 and O2 absorption in the vertical path to the surface at a number of wavelengths across a CO2 line near 1572 nm and an O2 line doublet near 764 nm. The measurements of CO2 and O2 absorption allow computing their vertically weighted number densities and then their ratios for estimating CO2 concentration relative to dry air. Since both the CO2 and O2 densities and their absorption line-width decrease with altitude, the absorption response (or weighting function) varies with both altitude and absorption wavelength. We have used some standard atmospheres and HITRAN 2008 spectroscopy to calculate the vertical weighting functions for two CO2 lines near 1571 nm and the O2 lines near 764.7 and 1260 nm for candidate online wavelength selections for ASCENDS. For CO2, the primary candidate on-line wavelengths are 10-12 pm away from line center with the weighting function peaking in the atmospheric boundary layer to measure CO2 sources and sinks at the surface. Using another on-line wavelength 3-5 pm away from line center allows the weighting function to peak in the mid- to upper troposphere, which is sensitive to CO2 transport in the free atmosphere. The Goddard CO2 sounder team developed an airborne precursor version of a space instrument. During the summers of 2009, 2010 and 2011 it has participated in airborne measurement campaigns over a variety of different sites in the US, flying with other NASA ASCENDS lidar candidates along with accurate in-situ atmospheric sensors. All flights used altitude patterns with measurements at steps in altitudes between 3 and 13 km, along with spirals from 13 km altitude to near the surface. Measurements from in-situ sensors allowed an accurate characterization of the CO2 and dry air vertical density profiles for each flight. Using this data, we have also computed some representative vertical weighting functions for CO2 lines near 1572 nm and the and O2 lines near 764 and 1270 nm and compared to the weighting functions of the NASA Langley's Continuous-Wave Laser Absorption Spectrometer for several flights in the ASCENDS airborne campaigns. The analysis provides guidance for measurement wavelength selection, retrieval algorithm development and ASCENDS mission simulation studies. Details of the methodology and computations for the airborne and future space measurements will be presented.

Fast tracking of wind speed with a differential absorption LiDAR system: first results of an experimental campaign at Stromboli volcano

NASA Astrophysics Data System (ADS)

Parracino, Stefano; Santoro, Simone; Maio, Giovanni; Nuvoli, Marcello; Aiuppa, Alessandro; Fiorani, Luca

2017-04-01

Carbon dioxide (CO2) is considered a precursor gas of volcanic eruptions by volcanologists. Monitoring the anomalous release of this parameter, we can retrieve useful information for the mitigation of volcanic hazards, such as for air traffic security. From a dataset collected during the Stromboli volcano field campaign, an assessment of the wind speed, in both horizontal and vertical paths, performing a fast tracking of this parameter was retrieved. This was determined with a newly designed shot-per-shot differential absorption LiDAR system operated in the near-infrared spectral region due to the simultaneous reconstruction of CO2 concentrations and wind speeds, using the same sample of LiDAR returns. A correlation method was used for the wind speed retrieval in which the transport of the spatial inhomogeneities of the aerosol backscattering coefficient, along the optical path of the system, was analyzed.

Simultaneous Measurements of CO2 Concentration and Temperature profiles using 1.6 μm DIAL in the Lower-Atmosphere

NASA Astrophysics Data System (ADS)

Shibata, Y.; Nagasawa, C.; Abo, M.

2016-12-01

High-accurate vertical carbon dioxide (CO2) profiles are highly desirable in the inverse method to improve quantification and understanding of the global sink and source of CO2, and also global climate change. We have developed a ground based 1.6μm differential absorption lidar (DIAL) to achieve measurements of vertical CO2 profiles in the atmosphere. As the spectra of absorption lines of any molecules are influenced basically by the temperature and pressure in the atmosphere, it is important to measure them simultaneously so that the better accuracy of the DIAL measurement is realized. The barometric formula can derive atmospheric pressure of each altitude using atmospheric pressure of ground level at the lidar site. Comparison of atmospheric pressure prlofiles calculated from this equation and those obtained from radiosonde observations at Tateno, Japan are consisted within 0.2 % below 3 km altitude. So, we have developed a 1.6 μm CO2 DIAL system for simultaneous measurements of the CO2 concentration and temperature profiles in the lower-atmosphere. Laser beams of three wavelengths around a CO2 absorption spectrum is transmitted alternately to the atmosphere. Moreover, the value of the retrieved CO2 concentration will be improved remarkably by processing the iteration assignment of CO2 concentration and temperature, which measured by these DIAL techniques. We have acheived vertical CO2 concentration and temperature profile from 0.5 to 2.0 km altitude by this DIAL system. In the next step, we will use this high accuracy CO2 concentration profile and back-trajectory analysis for the behavior analysis of the CO2 mass. This work was financially supported by the System Development Program for Advanced Measurement and Analysis of the Japan Science and Technology Agency.

Modeling of intensity-modulated continuous-wave laser absorption spectrometer systems for atmospheric CO(2) column measurements.

PubMed

Lin, Bing; Ismail, Syed; Wallace Harrison, F; Browell, Edward V; Nehrir, Amin R; Dobler, Jeremy; Moore, Berrien; Refaat, Tamer; Kooi, Susan A

2013-10-10

The focus of this study is to model and validate the performance of intensity-modulated continuous-wave (IM-CW) CO(2) laser absorption spectrometer (LAS) systems and their CO(2) column measurements from airborne and satellite platforms. The model accounts for all fundamental physics of the instruments and their related CO(2) measurement environments, and the modeling results are presented statistically from simulation ensembles that include noise sources and uncertainties related to the LAS instruments and the measurement environments. The characteristics of simulated LAS systems are based on existing technologies and their implementation in existing systems. The modeled instruments are specifically assumed to be IM-CW LAS systems such as the Exelis' airborne multifunctional fiber laser lidar (MFLL) operating in the 1.57 μm CO(2) absorption band. Atmospheric effects due to variations in CO(2), solar radiation, and thin clouds, are also included in the model. Model results are shown to agree well with LAS atmospheric CO(2) measurement performance. For example, the relative bias errors of both MFLL simulated and measured CO(2) differential optical depths were found to agree to within a few tenths of a percent when compared to the in situ observations from the flight of 3 August 2011 over Railroad Valley (RRV), Nevada, during the summer 2011 flight campaign. In addition, the horizontal variations in the model CO(2) differential optical depths were also found to be consistent with those from MFLL measurements. In general, the modeled and measured signal-to-noise ratios (SNRs) of the CO(2) column differential optical depths (τd) agreed to within about 30%. Model simulations of a spaceborne IM-CW LAS system in a 390 km dawn/dusk orbit for CO(2) column measurements showed that with a total of 42 W of transmitted power for one offline and two different sideline channels (placed at different locations on the side of the CO(2) absorption line), the accuracy of the τd measurements for surfaces similar to the playa of RRV, Nevada, will be better than 0.1% for 10 s averages. For other types of surfaces such as low-reflectivity snow and ice surfaces, the precision and bias errors will be within 0.23% and 0.1%, respectively. Including thin clouds with optical depths up to 1, the SNR of the τd measurements with 0.1 s integration period for surfaces similar to the playa of RRV, Nevada, will be greater than 94 and 65 for sideline positions placed +3 and +10  pm, respectively, from the CO(2) line center at 1571.112 nm. The CO(2) column bias errors introduced by the thin clouds are ≤0.1% for cloud optical depth ≤0.4, but they could reach ∼0.5% for more optically thick clouds with optical depths up to 1. When the cloud and surface altitudes and scattering amplitudes are obtained from matched filter analysis, the cloud bias errors can be further reduced. These results indicate that the IM-CW LAS instrument approach when implemented in a dawn/dusk orbit can make accurate CO(2) column measurements from space with preferential weighting across the mid to lower troposphere in support of a future ASCENDS mission.

A Direct Detection 1.6μm DIAL with Three Wavelengths for Measurements of Vertical CO2 Concentration and Temperature Profiles in the Atmosphere

NASA Astrophysics Data System (ADS)

Nagasawa, C.; Abo, M.; Shibata, Y.; Nagai, T.; Tsukamoto, M.

2012-12-01

We report the new 1.6 μm DIAL system that can measure the temperature profiles with the CO2 concentration profiles in the atmosphere because of improvement of measurement accuracy of the CO2 density and mixing ratio (ppm). We have developed a direct detection 1.6 μm differential absorption lidar (DIAL) technique to perform range-resolved measurements of vertical CO2 concentration profiles in the atmosphere [Sakaizawa et al. 2009]. Our 1.6 μm DIAL system consists of the Optical Parametric Generator (OPG) transmitter that excited by the LD pumped Nd:YAG laser with high repetition rate (500 Hz) and the receiving optics that included the near-infrared photomultiplier tube with high quantum efficiency operating at the photon counting mode and the telescope with larger aperture than that of the coherent detection method. Laser beams of three wavelengths around a CO2 absorption line is transmitted alternately to the atmosphere for measurements of CO2 concentration and temperature profiles. Moreover, a few retrieval algorithms of CO2-DIAL are also performed for improvement of measurement accuracy. The accurate vertical CO2 profiles in the troposphere are highly desirable in the inverse techniques to improve quantification and understanding of the global budget of CO2 and also global climate changes [Stephens et al. 2007]. In comparison with the ground-based monitoring network, CO2 measurements for vertical profiles in the troposphere have been limited to campaign-style aircraft and commercial airline observations with the limited spatial and temporal coverage. This work was financially supported by the System Development Program for Advanced Measurement and Analysis of the Japan Science and Technology Agency. References Sakaizawa, D., C. Nagasawa, T. Nagai, M. Abo, Y. Shibata, H. Nagai, M. Nakazato, and T. Sakai, Development of a 1.6μm differential absorption lidar with a quasi-phase-matching optical parametric oscillator and photon-counting detector for the vertical CO2 profile, Applied Optics, Vol.48, No.4, pp.748-757, 2009. Stephens, B. B. et al., Weak Northern and Strong Tropical Land Carbon Uptake from Vertical Profiles of Atmospheric CO2, Science 316, pp.1732-1735, 2007.

Laser Amplifier Development for the Remote Sensing of CO2 from Space

NASA Technical Reports Server (NTRS)

Yu, Anthony W.; Abshire, James B.; Storm, Mark; Betin, Alexander

2015-01-01

Accurate global measurements of tropospheric CO2 mixing ratios are needed to study CO2 emissions and CO2 exchange with the land and oceans. NASA Goddard Space Flight Center (GSFC) is developing a pulsed lidar approach for an integrated path differential absorption (IPDA) lidar to allow global measurements of atmospheric CO2 column densities from space. Our group has developed, and successfully flown, an airborne pulsed lidar instrument that uses two tunable pulsed laser transmitters allowing simultaneous measurement of a single CO2 absorption line in the 1570 nm band, absorption of an O2 line pair in the oxygen A-band (765 nm), range, and atmospheric backscatter profiles in the same path. Both lasers are pulsed at 10 kHz, and the two absorption line regions are sampled at typically a 300 Hz rate. A space-based version of this lidar must have a much larger lidar power-area product due to the approximately x40 longer range and faster along track velocity compared to airborne instrument. Initial link budget analysis indicated that for a 400 km orbit, a 1.5 m diameter telescope and a 10 second integration time, a approximately 2 mJ laser energy is required to attain the precision needed for each measurement. To meet this energy requirement, we have pursued parallel power scaling efforts to enable space-based lidar measurement of CO2 concentrations. These included a multiple aperture approach consists of multi-element large mode area fiber amplifiers and a single-aperture approach consists of a multi-pass Er:Yb:Phosphate glass based planar waveguide amplifier (PWA). In this paper we will present our laser amplifier design approaches and preliminary results.

High Energy, Narrow Linewidth 1572nm Eryb-Fiber Based MOPA for a Multi-Aperture CO2 Trace-Gas Laser Space Transmitter

NASA Technical Reports Server (NTRS)

Engin, Doruk; Mathason, Brian; Stephen, Mark; Yu, Anthony; Cao, He; Fouron, Jean-Luc; Storm, Mark

2016-01-01

Accurate global measurements of tropospheric CO2 mixing ratios are needed to study CO2 emissions and CO2 exchange with the land and oceans. NASA Goddard Space Flight Center (GSFC) is developing a pulsed lidar approach for an integrated path differential absorption (IPDA) lidar to allow global measurements of atmospheric CO2 column densities from space. Our group has developed, and successfully flown, an airborne pulsed lidar instrument that uses two tunable pulsed laser transmitters allowing simultaneous measurement of a single CO2 absorption line in the 1570 nm band, absorption of an O2 line pair in the oxygen A-band (765 nm), range, and atmospheric backscatter profiles in the same path. Both lasers are pulsed at 10 kHz, and the two absorption line regions are sampled at typically a 300 Hz rate. A space-based version of this lidar must have a much larger lidar power-area product due to the x40 longer range and faster along track velocity compared to airborne instrument. Initial link budget analysis indicated that for a 400 km orbit, a 1.5 m diameter telescope and a 10 second integration time, a 2 mJ laser energy is required to attain the precision needed for each measurement. To meet this energy requirement, we have pursued parallel power scaling efforts to enable space-based lidar measurement of CO2 concentrations. These included a multiple aperture approach consists of multi-element large mode area fiber amplifiers and a single-aperture approach consists of a multi-pass Er:Yb:Phosphate glass based planar waveguide amplifier (PWA). In this paper we will present our laser amplifier design approaches and preliminary results.

Airborne Two-Micron Double-Pulse IPDA Lidar Validation for Carbon Dioxide Measurements Over Land

NASA Astrophysics Data System (ADS)

Refaat, Tamer F.; Singh, Upendra N.; Yu, Jirong; Petros, Mulugeta; Remus, Ruben; Ismail, Syed

2018-04-01

An airborne double-pulse 2-μm Integrated Path Differential Absorption (IPDA) lidar has been developed at NASA LaRC for measuring atmospheric CO2. IPDA was validated using NASA B-200 aircraft over land and ocean under different conditions. IPDA evaluation for land vegetation returns, during full day background conditions, are presented. IPDA CO2 measurements compare well with model results driven from on-board insitu sensor data. These results also indicate that CO2 measurement bias is consistent with that from ocean surface returns.

Development of a 2-micron Pulsed Direct Detection IPDA Lidar for CO2 Measurement

NASA Astrophysics Data System (ADS)

Yu, J.; Petros, M.; Singh, U. N.

2013-12-01

NASA Langley is developing a 2-micron pulsed Integrated Path Differential Absorption (IPDA) lidar for atmospheric CO2 measurements. The high pulse energy, direct detection lidar operating at CO2 2-micron absorption band provides an alternate approach to measure CO2 concentrations with significant advantages. The objective of this development is to integrate an existing high energy double-pulsed 2-micron laser transmitter with a direct detection receiver and telescope to enable a first proof of principle demonstration of airborne direct detection CO2 measurements at 2-micron wavelength. It is expected to provide high-precision measurement capability by unambiguously eliminating contamination from aerosols and clouds that can bias the IPDA measurement. The system is scheduled to fly on NASA UC12 or B200 research aircrafts before the end of 2013. This paper will describe the design of the airborne 2-micron pulsed IPDA lidar system; the lidar operation parameters; the wavelength pair selection; laser transmitter energy, pulse rate, beam divergence, double pulse generation and accurate frequency control; detector characterization; telescope design; lidar structure design; and lidar signal to noise ratio estimation.

Advances in Pulsed Lidar Measurements of CO2 Column Concentrations from Aircraft and for Space

NASA Astrophysics Data System (ADS)

Abshire, J. B.; Ramanathan, A. K.; Allan, G. R.; Hasselbrack, W. E.; Riris, H.; Numata, K.; Mao, J.; Sun, X.

2016-12-01

We have demonstrated an improved pulsed, multiple-wavelength integrated path differential absorption lidar for measuring the tropospheric CO2 concentrations. The lidar measures the range resolved shape of the 1572.33 nm CO2 absorption line to scattering surfaces, including the ground and the tops of clouds. Airborne measurements have used both 30 and 15 fixed wavelength samples distributed across the line. Analysis estimates the lidar range and pulse energies at each wavelength 10 times per second. The retrievals solve for the CO2 absorption line shape and the column average CO2 concentrations by using radiative transfer calculations, the aircraft altitude and range to the scattering surface, and the atmospheric conditions. We compare these to CO2 concentrations from in-situ sensors. In recent campaigns the lidar used a step-locked laser diode source, and a new HgCdTe APD detector in the receiver. During August and September 2014 the ASCENDS campaign flew over the California Central Valley, a coastal redwood forest, desert areas, and above growing crops in Iowa. Analyses show the retrievals of lidar range and CO2 column absorption, and mixing ratio worked well when measuring over variable topography and through thin clouds and aerosols. The retrievals clearly show the decrease in CO2 concentration over growing cropland. Airborne lidar measurements of horizontal gradients of CO2 concentrations across Nevada, Colorado and Nebraska showed good agreement with those from a model of CO2 flux and transport (PCTM). In several flights the agreement of the lidar with the column average concentration was < 1ppm, with standard deviation of 0.9 ppm. Two additional flights were made in February 2016 using a larger laser spot size and an optimized receiver. These improved the sensitivity x3, and the retrievals show 0.7 ppm precision over the desert in 1 second averaging time. A summary of these results will be presented, along with on-going developments for a space version.

Advanced Sine Wave Modulation of Continuous Wave Laser System for Atmospheric CO2 Differential Absorption Measurements

NASA Technical Reports Server (NTRS)

Campbell, Joel F.; Lin, Bing; Nehrir, Amin R.

2014-01-01

NASA Langley Research Center in collaboration with ITT Exelis have been experimenting with Continuous Wave (CW) laser absorption spectrometer (LAS) as a means of performing atmospheric CO2 column measurements from space to support the Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission.Because range resolving Intensity Modulated (IM) CW lidar techniques presented here rely on matched filter correlations, autocorrelation properties without side lobes or other artifacts are highly desirable since the autocorrelation function is critical for the measurements of lidar return powers, laser path lengths, and CO2 column amounts. In this paper modulation techniques are investigated that improve autocorrelation properties. The modulation techniques investigated in this paper include sine waves modulated by maximum length (ML) sequences in various hardware configurations. A CW lidar system using sine waves modulated by ML pseudo random noise codes is described, which uses a time shifting approach to separate channels and make multiple, simultaneous online/offline differential absorption measurements. Unlike the pure ML sequence, this technique is useful in hardware that is band pass filtered as the IM sine wave carrier shifts the main power band. Both amplitude and Phase Shift Keying (PSK) modulated IM carriers are investigated that exibit perfect autocorrelation properties down to one cycle per code bit. In addition, a method is presented to bandwidth limit the ML sequence based on a Gaussian filter implemented in terms of Jacobi theta functions that does not seriously degrade the resolution or introduce side lobes as a means of reducing aliasing and IM carrier bandwidth.

Explaining the differential solubility of flue gas components in ionic liquids from first-principle calculations.

PubMed

Prasad, B Ram; Senapati, Sanjib

2009-04-09

Flue gas is greatly responsible for acid rain formation and global warming. New generation ionic liquids (ILs) have potential in controlling the flue gas emissions, as they acquire high absorptivity for the component gases SO(2), CO(2), etc. The association of the IL-gas interactions to the absorptivity of gas molecules in ILs is, however, poorly understood. In this paper, we present a molecular level description of the interactions of ILs with SO(2), CO(2), and N(2) and show its implications to the differential gas solubility. Our results indicate that the IL anion-gas interactions play a key role in deciding the gas solubility in ILs, particularly for polar gases such as SO(2). On the other hand, regular solution assumption applies to N(2) solubility. In accordance with the previous theoretical and experimental findings, our results also imply that the IL anions dominate the interactions with gas molecules while the cations play a secondary role and the underlying fluid structures of the ILs remain unperturbed by the addition of gas molecules.

Monitoring Atmospheric CO2 From Space: Challenge & Approach

NASA Technical Reports Server (NTRS)

Lin, Bing; Harrison, F. Wallace; Nehrir, Amin; Browell, Edward; Dobler, Jeremy; Campbell, Joel; Meadows, Byron; Obland, Michael; Kooi, Susan; Fan, Tai-Fang;

The transverse instability in a differentially heated vertical cavity filled with molecular radiating gases. I. Linear stability analysis

NASA Astrophysics Data System (ADS)

Borget, V.; Bdéoui, F.; Soufiani, A.; Le Quéré, P.

2001-05-01

Radiation effects on the onset of the transverse instability in a differentially heated vertical cavity containing molecular emitting and absorbing gases in the so-called conduction regime is studied theoretically. Radiative transfer is treated using the full integro-differential formulation. The neutral stability curves are determined using a combined Galerkin-collocation method based on Chebyshev polynomials. A modified correlated-k model and the absorption distribution function model are used in order to take into account the spectral structure of the absorption coefficient for radiating molecules such as H2O and CO2. For transparent media, perfect agreement is found with the available data reported in the literature and, particularly, the principle of exchange of stability is found to hold for Prandtl number values less than 12.46. The study of gray media allows us to examine the basic mechanisms that yield to the onset of transverse instability as traveling waves. For real radiating gases, a parametric study for H2O and CO2 is reported. It is shown that the radiative transfer delays the onset of the transverse instability and this delay increases with temperature and decreases with boundary emissivities, while layer depth effects depend on the level of saturation of the gas active absorption bands. Whatever the gas considered, it is found that neither radiation effect on the basic flow nor the radiative power disturbances can be neglected.

Analysis of Pulsed Airborne Lidar Measurements of Atmospheric CO2 Column Absorption from 3-13 km Altitudes

NASA Technical Reports Server (NTRS)

Abshire, James B.; Weaver, Clark J.; Riris, Haris; Mao, Jianping; Sun, Xiaoli; Allan, Graham R.; Hasselbrack, William; Browell, Edward V.

2011-01-01

We have developed a pulsed lidar technique for measuring the tropospheric CO2 concentrations as a candidate for NASA's ASCENDS space mission [1]. It uses two pulsed laser transmitters allowing simultaneous measurement of a CO2 absorption line in the 1575 nm band, O2 extinction in the Oxygen A-band, surface height and backscatter profile. The lasers are precisely stepped in wavelength across the CO2 line and an O2 line region during the measurement. The direct detection receiver measures the energies of the laser echoes from the surface along with the range profile of scattering in the path. The column densities for the CO2 and O2 gases are estimated from the ratio of the on- and off-line signals via the integrated path differential absorption (IPDA) technique. The time of flight of the laser pulses is used to estimate the height of the scattering surface and to reject laser photons scattered in the atmosphere. We developed an airborne lidar to demonstrate an early version of the CO2 measurement from the NASA Glenn Lear-25 aircraft. The airborne lidar stepped the pulsed laser's wavelength across the selected CO2 line with 20 wavelength steps per scan. The line scan rate is 450 Hz, the laser pulse widths are 1 usec, and laser pulse energy is 24 uJ. The time resolved laser backscatter is collected by a 20 cm telescope, detected by a NIR photomultiplier and is recorded on every other reading by a photon counting system [2]. During August 2009 we made a series of 2.5 hour long flights and measured the atmospheric CO2 absorption and line shapes using the 1572.33 nm CO2 line. Measurements were made at stepped altitudes from 3-13 km over locations in the US, including the SGP ARM site in Oklahoma, central Illinois, north-eastern North Carolina, and over the Chesapeake Bay and the eastern shore of Virginia. Although the received signal energies were weaker than expected for ASCENDS, clear CO2 line shapes were observed at all altitudes, and some measurements were made through thin clouds. The Oklahoma and east coast flights were coordinated with a LaRC/ITT CO2 lidar on the LaRC UC-12 aircraft, and in-situ measurements were made using its CO2 sensor and radiosondes. We have conducted an analysis of the ranging and IPDA lidar measurements from these four flights. Most flights had 5-6 altitude steps with 200-300 seconds of recorded measurements per step. We used a cross-correlation approach to process the laser echo records. This was used to estimate the range to the scattering surface, to define the edges of the laser pulses and to determine echo pulse energy at each wavelength. We used a minimum mean square approach to fit an instrument response function and to solve for the best-fit CO2 absorption line shape. We then calculated the differential optical depth (DOD) of the fitted CO2 line. We computed its statistics at the various altitude steps, and compare them to the DODs calculated from spectroscopy based on HITRAN 2008 and the column conditions calculated from the airborne in-situ readings. The results show the lidar and in-situ measurements have very similar DOD change with altitude and greater than 10 segments per flight where the scatter in the lidar measurements are less than or equal to 1ppm. We also present the results from subsequent CO2 column absorption measurements, which were made with stronger detected signals during three flights on the NASA DC-8 over the southwestern US in during July 2010.

Widely-Tunable Parametric Short-Wave Infrared Transmitter for CO2 Trace Detection (POSTPRINT)

DTIC Science & Technology

2013-01-01

F. Amzajerdian, J. Yu, R. E. Davis, S. Ismail, S. Vay, M. J. Kavaya, and U. N. Singh, “ Coherent differential absorption lidar measurements of CO2... Doppler lidar system for wind sensing,” Appl. Opt. 46(11), 1953–1962 (2007). 1. Introduction Over the short-wave infrared (SWIR) spectrum, which is...fiber. References and links 1. M. Ebrahim-Zadeh, and I. T. Sorokina, eds., Mid-Infrared Coherent Sources and Applications (Springer, 2007). 2. C

DIAL with heterodyne detection including speckle noise: Aircraft/shuttle measurements of O3, H2O, and NH3 with pulsed tunable CO2 lasers

NASA Technical Reports Server (NTRS)

Brockman, P.; Hess, R. V.; Staton, L. D.; Bair, C. H.

1980-01-01

Atmospheric trace constituent measurements with higher vertical resolution than attainable with passive radiometers are discussed. Infrared differential absorption lidar (DIAL), which depends on Mie scattering from aerosols, has special advantages for tropospheric and lower stratospheric applications and has great potential importance for measurements from shuttle and aircraft. Differential absorption lidar data reduction involves comparing large amplitude signals which have small differences. The accuracy of the trace constituent concentration inferred from DIAL measurements depends strongly on the errors in determining the amplitude of the signals. Thus, the commonly used SNR expression (signal divided by noise in the absence of signal) is not adequate to describe DIAL measurement accuracy and must be replaced by an expression which includes the random coherent (speckle) noise within the signal. A comprehensive DIAL computer algorithm is modified to include heterodyne detection and speckle noise. Examples for monitoring vertical distributions of O3, H2O, and NH3 using a ground-, aircraft-, or shuttle-based pulsed tunable CO2 laser DIAL system are given.

Development of tunable high pressure CO2 laser for lidar measurements of pollutants and wind velocities

NASA Technical Reports Server (NTRS)

Levine, J. S.; Guerra, M.; Javan, A.

1980-01-01

The problem of laser energy extraction at a tunable monochromatic frequency from an energetic high pressure CO2 pulsed laser plasma, for application to remote sensing of atmospheric pollutants by Differential Absorption Lidar (DIAL) and of wind velocities by Doppler Lidar, was investigated. The energy extraction principle analyzed is based on transient injection locking (TIL) at a tunable frequency. Several critical experiments for high gain power amplification by TIL are presented.

Lidar Observations of Atmospheric CO2 Column During 2014 Summer Flight Campaigns

NASA Technical Reports Server (NTRS)

Lin, Bing; Harrison, F. Wallace; Fan, Tai-Fang

2015-01-01

Advanced knowledge in atmospheric CO2 is critical in reducing large uncertainties in predictions of the Earth' future climate. Thus, Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) from space was recommended by the U.S. National Research Council to NASA. As part of the preparation for the ASCENDS mission, NASA Langley Research Center (LaRC) and Exelis, Inc. have been collaborating in development and demonstration of the Intensity-Modulated Continuous-Wave (IM-CW) lidar approach for measuring atmospheric CO2 column from space. Airborne laser absorption lidars such as the Multi-Functional Fiber Laser Lidar (MFLL) and ASCENDS CarbonHawk Experiment Simulator (ACES) operating in the 1.57 micron CO2 absorption band have been developed and tested to obtain precise atmospheric CO2 column measurements using integrated path differential absorption technique and to evaluate the potential of the space ASCENDS mission. This presentation reports the results of our lidar atmospheric CO2 column measurements from 2014 summer flight campaign. Analysis shows that for the 27 Aug OCO-2 under flight over northern California forest regions, significant variations of CO2 column approximately 2 ppm) in the lower troposphere have been observed, which may be a challenge for space measurements owing to complicated topographic condition, heterogeneity of surface reflection and difference in vegetation evapotranspiration. Compared to the observed 2011 summer CO2 drawdown (about 8 ppm) over mid-west, 2014 summer drawdown in the same region measured was much weak (approximately 3 ppm). The observed drawdown difference could be the results of the changes in both meteorological states and the phases of growing seasons. Individual lidar CO2 column measurements of 0.1-s integration were within 1-2 ppm of the CO2 estimates obtained from on-board in-situ sensors. For weak surface reflection conditions such as ocean surfaces, the 1- s integrated signal-to-noise ratio (SNR) of lidar measurements at 11 km altitude reached 376, which was equivalent to a 10-s CO2 error 0.33 ppm. For the entire processed 2014 summer flight campaign data, the mean differences between lidar remote sensed and in-situ estimated CO2 values were about -0.013 ppm. These results indicate that current laser absorption lidar approach could meet space measurement requirements for CO2 science goals.

Lidar measurements of the column CO2 mixing ratio made by NASA Goddard's CO2 Sounder during the NASA ASCENDS 2014 Airborne campaign.

NASA Astrophysics Data System (ADS)

Ramanathan, A. K.; Mao, J.; Abshire, J. B.; Kawa, S. R.

2015-12-01

Remote sensing measurements of CO2 from space can help improve our understanding of the carbon cycle and help constrain the global carbon budget. However, such measurements need to be sufficiently accurate to detect small (1 ppm) changes in the CO2 mixing ratio (XCO2) against a large background (~ 400 ppm). Satellite measurements of XCO2 using passive spectrometers, such as those from the Japanese GOSAT (Greenhouse gas Observing Satellite) and the NASA OCO-2 (Orbiting Carbon Observatory-2) are limited to daytime sunlit portions of the Earth and are susceptible to biases from clouds and aerosols. For this reason, NASA commissioned the formulation study of ASCENDS a space-based lidar mission. NASA Goddard Space Flight Center's CO2 Sounder lidar is one candidate approach for the ASCENDS mission. The NASA GSFC CO2 Sounder measures the CO2 mixing ratio using a pulsed multi-wavelength integrated path differential absorption (IPDA) approach. The CO2 Sounder has flown in the 2011, 2013 and 2014 ASCENDS airborne campaigns over the continental US, and has produced measurements in close agreement with in situ measurements of the CO2 column. In 2014, the CO2 Sounder upgraded its laser with a precision step-locked diode laser source to improve the lidar wavelength position accuracy. It also improved its optical receiver with a low-noise, high efficiency, HgCdTe avalanche photo diode detector. The combination of these two technologies enabled lidar XCO2 measurements with unprecedented accuracy. In this presentation, we show analysis from the ASCENDS 2014 field campaign, exploring: (1) Horizontal XCO2 gradients measured by the lidar, (2) Comparisons of lidar XCO2 measurements against the Parameterized Chemistry Transport Model (PCTM), and (3) Lidar column water vapor measurements using a HDO absorption line that occurs next to the CO2 absorption line. This can reduce the uncertainty in the dry air column used in XCO2 retrievals.

Analysis of Pulsed Lidar Measurements of Atmospheric CO2 Column Absorption During the ASCENDS 2009-2011 Airborne Campaigns

NASA Technical Reports Server (NTRS)

Abshire, J. B.; Weaver, C. J.; Riris, H.; Mao, J.; Sun, X; Allan, G. R.; Hasselbrack, W. E.; Browell, E. V.

2012-01-01

We have developed a pulsed lidar technique for measuring the tropospheric CO2 concentrations as a candidate for NASA's ASCENDS mission and have demonstrated the CO2 and O2 measurements from aircraft. Our technique uses two pulsed lasers allowing simultaneous measurement of a single CO2 absorption line near 1572 nm, O2 extinction in the Oxygen A-band, surface height and backscatter profile. The lasers are stepped in wavelength across the CO2 line and an O2 line doublet during the measurement. The column densities for the CO2 and O2 are estimated from the differential optical depths (DOD) of the scanned absorption lines via the IPDA technique. For the 2009 ASCENDS campaign we flew the CO2 lidar on a Lear-25 aircraft, and measured the absorption line shapes of the CO2 line using 20 wavelength samples per scan. Measurements were made at stepped altitudes from 3 to 12.6 km over the Lamont OK, central Illinois, North Carolina, and over the Virginia Eastern Shore. Although the received signal energies were weaker than expected for ASCENDS, clear CO2 line shapes were observed at all altitudes. Most flights had 5-6 altitude steps with 200-300 seconds of recorded measurements per step. We averaged every 10 seconds of measurements and used a cross-correlation approach to estimate the range to the scattering surface and the echo pulse energy at each wavelength. We then solved for the best-fit CO2 absorption line shape, and calculated the DOD of the fitted CO2 line, and computed its statistics at the various altitude steps. We compared them to CO2 optical depths calculated from spectroscopy based on HITRAN 2008 and the column number densities calculated from the airborne in-situ readings. The 2009 measurements have been analyzed and they were similar on all flights. The results show clear CO2 line shape and absorption signals, which follow the expected changes with aircraft altitude from 3 to 13 km. They showed the expected nearly the linear dependence of DOD vs altitude. The measurements showed 1 ppm random errors for 8-10 km altitudes and 30 sec averaging times. For the 2010 ASCENDS campaigns we flew the CO2lidar on the NASA DC-8 and added an 02lidar channel. During July 2010 we made measurements of CO2 and O2 column absorption during longer flights over Railroad Valley NV, the Pacific Ocean and over Lamont OK. CO2 measurements were made with 30 steps/scan, 300 scans/sec and improved line resolution and receiver sensitivity. Analysis of the 2010 CO2 measurements shows the expected linear change of DOD with altitude. For measurements at altitudes> 6 km the random errors were 0.3 ppm for 80 sec averaging times. For the summer 2011 ASCENDS campaigns we made further improvements to the lidar's CO2 line scan and receiver sensitivity. We demonstrated measurements over the California Central Valley, to stratus cloud tops over the Pacific Ocean, over mountain regions with snow, and over several areas with broken clouds. Details of the lidar measurements and their analysis will be described in the presentation.

Column-Integrated CO2 Concentrations Measured by MFLL During ACT-America Flight Campaigns

NASA Astrophysics Data System (ADS)

Erxleben, W. H.; McGregor, D.; Kooi, S. A.; Campbell, J.; Dobler, J. T.; Pal, S.; Lin, B.; Browell, E. V.; O'Dell, C.; DiGangi, J. P.; Bell, E.

2017-12-01

The Multifunction Fiber Laser Lidar (MFLL), designed, built, and operated by Harris Space and Intelligence Systems, is a key instrument aboard the NASA Earth Venture Suborbital mission known as Atmospheric Carbon and Transport - America (ACT-America). The mission's goals include improving estimates of atmospheric transport and fluxes of CO2 and CH4, and evaluating sensitivity of the OCO-2 satellite to regional CO2 variability. ACT-America includes five flight campaigns on two NASA aircraft between 2016 and 2019. The MFLL instrument has been under evaluation in collaboration with NASA Langley Research Center since 2005 and installed on one of NASA's C-130s for ACT-America campaigns since 2016. MFLL measures the integrated path differential absorption in the atmospheric column between the airplane and the ground caused by atmospheric gases (primarily CO2 and H2O). From the differential absorption, the integrated differential optical depth is obtained. The waveforms used to encode and identify the individual wavelengths of light also enable the instrument to determine range to the surface. The measured range and optical depth, together with spectroscopic and meteorological information, enable the column-integrated concentration of CO2 to be retrieved. Through the first two flight campaigns, MFLL has performed 47 flight sorties totaling 170 hours with zero critical failures. Improvements were implemented after the first campaign to reduce harmonic crosstalk and to eliminate both a short-period etalon effect and a longer-period oscillation. MFLL will be flying on the third ACT-America campaign in Fall 2017. We will present a brief review of the measurement method, the instrument performance, and the improvements made over the course of ACT-America. We will also present the most recent results from the first two campaigns covering various altitudes and scenarios: frontal crossings, fair-weather patterns, and OCO-2 underflights. These results will be compared with model predictions generated from in situ instruments and meteorological data sources.

Lidar sounding of volcanic plumes

NASA Astrophysics Data System (ADS)

Fiorani, Luca; Aiuppa, Alessandro; Angelini, Federico; Borelli, Rodolfo; Del Franco, Mario; Murra, Daniele; Pistilli, Marco; Puiu, Adriana; Santoro, Simone

2013-10-01

Accurate knowledge of gas composition in volcanic plumes has high scientific and societal value. On the one hand, it gives information on the geophysical processes taking place inside volcanos; on the other hand, it provides alert on possible eruptions. For this reasons, it has been suggested to monitor volcanic plumes by lidar. In particular, one of the aims of the FP7 ERC project BRIDGE is the measurement of CO2 concentration in volcanic gases by differential absorption lidar. This is a very challenging task due to the harsh environment, the narrowness and weakness of the CO2 absorption lines and the difficulty to procure a suitable laser source. This paper, after a review on remote sensing of volcanic plumes, reports on the current progress of the lidar system.

Sensitivity Studies for Space-based Measurements of Atmospheric Total Column Carbon Dioxide Using Reflected Sunlight

NASA Technical Reports Server (NTRS)

Mao, Jianping; Kawa, S. Randolph

2003-01-01

A series of sensitivity studies is carried out to explore the feasibility of space-based global carbon dioxide (CO2) measurements for global and regional carbon cycle studies. The detection method uses absorption of reflected sunlight in the CO2 vibration-rotation band at 1.58 micron. The sensitivities of the detected radiances are calculated using the line-by-line model (LBLRTM), implemented with the DISORT (Discrete Ordinates Radiative Transfer) model to include atmospheric scattering in this band. The results indicate that (a) the small (approx.1%) changes in CO2 near the Earth's surface are detectable in this CO2 band provided adequate sensor signal-to-noise ratio and spectral resolution are achievable; (b) the effects of other interfering constituents, such as water vapor, aerosols and cirrus clouds, on the radiance are significant but the overall effects of the modification of light path length on total back-to-space radiance sensitivity to CO2 change are minor for general cases, which means that generally the total column CO2 can be derived in high precision from the ratio of the on-line center to off-line radiances; (c) together with CO2 gas absorption aerosol/cirrus cloud layer has differential scattering which may result in the modification of on-line to off-line radiance ratio which could lead a large bias in the total column CO2 retrieval. Approaches to correct such bias need further investigation. (d) CO2 retrieval requires good knowledge of the atmospheric temperature profile, e.g. approximately 1K RMS error in layer temperature, which is achievable from new atmospheric sounders in the near future; (e) the atmospheric path length, over which the CO2 absorption occurs, should be known in order to correctly interpret horizontal gradients of CO2 from the total column CO2 measurement; thus an additional sensor for surface pressure measurement needs to be attached for a complete measurement package.

Pulsed Lidar Measurements of Atmospheric CO2 Column Absorption and Range During the ASCENDS 2009-2011 Airborne Campaigns

NASA Technical Reports Server (NTRS)

Abshire, J. B.; Weaver, C. J.; Riris, H.; Mao, J.; Sun, X.; Allan, G. R.; Hasselbrack, W. E.; Browell, E. V.

2012-01-01

We have developed a pulsed lidar technique for measuring the tropospheric CO2 concentrations as a candidate for NASA's ASCENDS mission and have demonstrated the CO2 and O2 measurements from aircraft. Our technique uses two pulsed lasers allowing simultaneous measurement of a single CO2 absorption line near 1572 nm, O2 extinction in the Oxygen A-band, surface height and backscatter profile. The lasers are stepped in wavelength across the CO2 line and an O2 line doublet during the measurement. The column densities for the CO2 and O2 are estimated from the differential optical depths (DOD) of the scanned absorption lines via the IPDA technique. For the 2009 ASCENDS campaign we flew the CO2 lidar only on a Lear-25 aircraft, and measured the absorption line shapes of the CO2 line using 20 wavelength samples per scan. Measurements were made at stepped altitudes from 3 to 12.6 km over the Lamont OK, central Illinois, North Carolina, and over the Virginia Eastern Shore. Although the received signal energies were weaker than expected for ASCENDS, clear C02 line shapes were observed at all altitudes. Most flights had 5-6 altitude steps with 200-300 seconds of recorded measurements per step. We averaged every 10 seconds of measurements and used a cross-correlation approach to estimate the range to the scattering surface and the echo pulse energy at each wavelength. We then solved for the best-fit CO2 absorption line shape, and calculated the DOD of the fitted CO2 line, and computed its statistics at the various altitude steps. We compared them to CO2 optical depths calculated from spectroscopy based on HITRAN 2008 and the column number densities calculated from the airborne in-situ readings. The 2009 measurements have been analyzed in detail and they were similar on all flights. The results show clear CO2 line shape and absorption signals, which follow the expected changes with aircraft altitude from 3 to 13 km. They showed the expected nearly the linear dependence of DOD vs altitude. The measurements showed -1 ppm random errors for 8-10 km altitudes and -30 sec averaging times. For the 2010 ASCENDS campaigns we flew the CO2 lidar on the NASA DC-8 and added an O2 lidar channel. During July 2010 we made measurements of CO2 and O2 column absorption during longer flights over Railroad Valley NV, the Pacific Ocean and over Lamont OK. CO2 measurements were made with 30 steps/scan, 300 scans/sec and improved line resolution and receiver sensitivity. Analysis of the 2010 CO2 measurements shows the expected -linear change of DOD with altitude. For measurements at altitudes> 6 km the random errors were 0.3 ppm for 80 sec averaging times. For the summer 2011 ASCENDS campaigns we made further improvements to the lidar's CO2 line scan and receiver sensitivity. The seven flights in the 2011 Ascends campaign were flown over a wide variety of surface and cloud conditions in the US, which produced a wide variety of lidar signal conditions. Details of the lidar measurements and their analysis will be described in the presentation.

Carbon dioxide sequestration monitoring and verification via laser based detection system in the 2 mum band

NASA Astrophysics Data System (ADS)

Humphries, Seth David

Carbon Dioxide (CO2) is a known contributor to the green house gas effect. Emissions of CO2 are rising as the global demand for inexpensive energy is placated through the consumption and combustion of fossil fuels. Carbon capture and sequestration (CCS) may provide a method to prevent CO2 from being exhausted to the atmosphere. The carbon may be captured after fossil fuel combustion in a power plant and then stored in a long term facility such as a deep geologic feature. The ability to verify the integrity of carbon storage at a location is key to the success of all CCS projects. A laser-based instrument has been built and tested at Montana State University (MSU) to measure CO2 concentrations above a carbon storage location. The CO2 Detection by Differential Absorption (CODDA) Instrument uses a temperature-tunable distributed feedback (DFB) laser diode that is capable of accessing a spectral region, 2.0027 to 2.0042 mum, that contains three CO2 absorption lines and a water vapor absorption line. This instrument laser is aimed over an open-air, two-way path of about 100 m, allowing measurements of CO2 concentrations to be made directly above a carbon dioxide release test site. The performance of the instrument for carbon sequestration site monitoring is studied using a newly developed CO2 controlled release facility. The field and CO2 releases are managed by the Zero Emissions Research Technology (ZERT) group at MSU. Two test injections were carried out through vertical wells simulating seepage up well paths. Three test injections were done as CO2 escaped up through a slotted horizontal pipe simulating seepage up through geologic fault zones. The results from these 5 separate controlled release experiments over the course of three summers show that the CODDA Instrument is clearly capable of verifying the integrity of full-scale CO2 storage operations.

Cubic and Rhombohedral Heterobimetallic Networks Constructed from Uranium, Transition Metals, and Phosphonoacetate. New Methods for Constructing Porous Materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alsobrook, Andera N.; Hauser, B. G.; Hupp, Joseph T.

2010-11-01

Four heterobimetallic U(VI)/M(II) (M = Mn, Co, Cd) carboxyphosphonates have been synthesized. M 2[(UO 2) 6(PO 3CH 2CO 2) 3O 3(OH)(H 2O) 2]·16H 2O (M = Mn(II), Co(II), and Cd(II)) adopt cubic three-dimensional network structures with large cavities approximately 16 Å in diameter that are filled with co-crystallized water molecules. [Cd 3(UO 2) 6(PO 3CH 2CO 2) 6(H 2O) 13]·6H 2 O forms a rhombohedral channel structure with hydrated Cd(II) within the channels. The cubic compound (Co) displays differential gas absorption with a surface area for CO 2 uptake of 40 m 2 g -1 at 273 K, and nomore » uptake of N 2 at 77 K.« less

High Repetition Rate Pulsed 2-Micron Laser Transmitter for Coherent CO2 DIAL Measurement

NASA Technical Reports Server (NTRS)

Singh, Uprendra N.; Bai, Yingxin; Yu, Jirong; Petros, Mulugeta; Petzar, Paul J.; Trieu, Bo C.; Lee, Hyung

2009-01-01

A high repetition rate, highly efficient, Q-switched 2-micron laser system as the transmitter of a coherent differential absorption lidar for CO2 measurement has been developed at NASA Langley Research Center. Such a laser transmitter is a master-slave laser system. The master laser operates in a single frequency, either on-line or off-line of a selected CO2 absorption line. The slave laser is a Q-switched ring-cavity Ho:YLF laser which is pumped by a Tm:fiber laser. The repetition rate can be adjusted from a few hundred Hz to 10 kHz. The injection seeding success rate is from 99.4% to 99.95%. For 1 kHz operation, the output pulse energy is 5.5mJ with the pulse length of approximately 50 ns. The optical-to-optical efficiency is 39% when the pump power is 14.5W. The measured standard deviation of the laser frequency jitter is about 3 MHz.

He-Ne and CW CO2 laser long-path systems for gas detection

NASA Technical Reports Server (NTRS)

Grant, W. B.

1986-01-01

This paper describes the design and testing of a laboratory prototype dual He-Ne laser system for the detection of methane leaks from underground pipelines and solid-waste landfill sites using differential absorption of radiation backscattered from topographic targets. A laboratory-prototype dual CW carbon dioxide laser system also using topographic backscatter is discussed, and measurement results for methanol are given. With both systems, it was observed that the time-varying differential absorption signal was useful in indicating the presence of a gas coming from a nearby source. Limitations to measurement sensitivity, especially the role of speckle and atmospheric turbulence, are described. The speckle results for hard targets are contrasted with those from atmospheric aerosols. The appendix gives appropriate laser lines and values of absorption coefficients for the hydrazine fuel gases.

High Repetition Rate and Frequency Stabilized Ho:YLF Laser for CO2 Differential Absorption Lidar

NASA Technical Reports Server (NTRS)

Bai, Yingxin; Yu, Jirong; Petros, M.; Petzar, Pau; Trieu, Bo; Lee, Hyung; Singh, U.

2009-01-01

High repetition rate operation of an injection seeded Ho:YLF laser has been demonstrated. For 1 kHz operation, the output pulse energy reaches 5.8mJ and the optical-to-optical efficiency is 39% when the pump power is 14.5W.

Negative induced absorption and negative index of refraction for iron doped potash-alumina-borate glasses subjected to thermal-radiation treatment

NASA Astrophysics Data System (ADS)

Salakhitdinov, Amritdin; Ibragimova, Elvira; Salakhitdinova, Maysara

2018-02-01

This work experimentally revealed, that 60Co-gamma-irradiation of potash-alumina-borate glasses doped with 1 and 2 mass% of iron oxide to the dose of 1.7 MR in the temperature range of 150-300 °C induced differential optical density changes within - 6 ≤ Δ D ≤ 0 in the wave length range of 300-350 nm, which is characteristic for meta-material. Calculations have shown that variation of optical refraction index within - 0.05 ≤ Δ n ω ≤ 0.05 due to microstructure transformation causes changes in the differential absorption index of the glass - 0.5 < Δ α ω < 0.55.

Comparison of Carbon Dioxide Airborne Measurement over Land and Ocean using 2-μm Double-Pulse Integrated Path Differential Absorption Lidar

NASA Astrophysics Data System (ADS)

Refaat, T. F.; Singh, U. N.; Petros, M.; Yu, J.; Remus, R.; Ismail, S.

2017-12-01

An airborne Integrated Path Differential Absorption (IPDA) lidar has been developed and validated at NASA Langley Research Center for atmospheric carbon dioxide column measurements. The instrument consists of a tunable, high-energy 2-μm double pulse laser transmitter and 0.4 m telescope receiver coupled to an InGaAs pin detection system. The instrument was validated for carbon dioxide (CO2) measurements from ground and airborne platforms, using a movable lidar trailer and the NASA B-200 aircraft. Airborne validation was conducted over the ocean by comparing the IPDA CO2 optical depth measurement to optical depth model derived using NOAA airborne CO2 air-sampling. Another airborne validation was conducted over land vegetation by comparing the IPDA measurement to a model derived using on-board in-situ measurements using an absolute, non-dispersive infrared gas analyzer (LiCor 840A). IPDA range measurements were also compared to rangefinder and Global Positioning System (GPS) records during ground and airborne validation, respectively. Range measurements from the ground indicated a 0.93 m IPDA range measurement uncertainty, which is limited by the transmitted laser pulse and detection system properties. This uncertainty increased to 2.80 and 7.40 m over ocean and land, due to fluctuations in ocean surface and ground elevations, respectively. IPDA CO2 differential optical depth measurements agree with both models. Consistent CO2 optical depth biases were well correlated with the digitizer full scale input range settings. CO2 optical depth measurements over ocean from 3.1 and 6.1 km altitudes indicated 0.95% and 0.83% uncertainty, respectively, using 10 second (100 shots) averaging. Using the same averaging 0.40% uncertainty was observed over land, from 3.4 km altitude, due to higher surface reflectivity, which increases the return signal power and enhances the signal-to-noise ratio. However, less uncertainty is observed at higher altitudes due to reduced signal shot noise, indicating that detection system noise-equivalent-power dominates the error. These results show that the IPDA technique is well suited for space-based platforms, which includes larger column content integration that enhances the measurement sensitivity.

Towards understanding the variability in biospheric CO2 fluxes: using FTIR spectrometry and a chemical transport model to investigate the sources and sinks of carbonyl sulfide and its link to CO2

NASA Astrophysics Data System (ADS)

Wang, Y.; Deutscher, N. M.; Palm, M.; Warneke, T.; Notholt, J.; Baker, I.; Berry, J.; Suntharalingam, P.; Jones, N.; Mahieu, E.; Lejeune, B.; Campbell, J. E.; Wolf, A.; Kremser, S.

2015-09-01

Understanding carbon dioxide (CO2) biospheric processes is of great importance because the terrestrial exchange drives the seasonal and inter-annual variability of CO2 in the atmosphere. Atmospheric inversions based on CO2 concentration measurements alone can only determine net biosphere fluxes, but not differentiate between photosynthesis (uptake) and respiration (production). Carbonyl sulfide (OCS) could provide an important additional constraint: it is also taken up by plants during photosynthesis but not emitted during respiration, and therefore is a potential mean to differentiate between these processes. Solar absorption Fourier Transform InfraRed (FTIR) spectrometry allows for the retrievals of the atmospheric concentrations of both CO2 and OCS from measured solar absorption spectra. Here, we investigate co-located and quasi-simultaneous FTIR measurements of OCS and CO2 performed at three selected sites located in the Northern Hemisphere. These measurements are compared to simulations of OCS and CO2 using a chemical transport model (GEOS-Chem). The OCS simulations are driven by different land biospheric fluxes to reproduce the seasonality of the measurements. Increasing the plant uptake of Kettle et al. (2002a) by a factor of three resulted in the best comparison with FTIR measurements. However, there are still discrepancies in the latitudinal distribution when comparing with HIPPO (HIAPER Pole-to-Pole Observations) data spanning both hemispheres. The coupled biospheric fluxes of OCS and CO2 from the simple biosphere model (SiB) are used in the study and compared to measurements. The CO2 simulation with SiB fluxes agrees with the measurements well, while the OCS simulation reproduced a weaker drawdown than FTIR measurements at selected sites, and a smaller latitudinal gradient in the Northern Hemisphere during growing season. An offset in the timing of the seasonal cycle minimum between SiB simulation and measurements is also seen. Using OCS as a photosynthesis proxy can help to understand how the biospheric processes are reproduced in models and to further understand the carbon cycle in the real world.

Development of an advanced Two-Micron triple-pulse IPDA lidar for carbon dioxide and water vapor measurements

NASA Astrophysics Data System (ADS)

Petros, Mulugeta; Refaat, Tamer F.; Singh, Upendra N.; Yu, Jirong; Antill, Charles; Remus, Ruben; Taylor, Bryant D.; Wong, Teh-Hwa; Reithmaier, Karl; Lee, Jane; Ismail, Syed; Davis, Kenneth J.

2018-04-01

An advanced airborne triple-pulse 2-μm integrated path differential absorption (IPDA) lidar is under development at NASA Langley Research Center that targets both carbon dioxide (CO2) and water vapor (H2O) measurements simultaneously and independently. This lidar is an upgrade to the successfully demonstrated CO2 2-μm double-pulse IPDA. Upgrades include high-energy, highrepetition rate 2-μm triple-pulse laser transmitter, innovative wavelength control and advanced HgCdTe (MCT) electron-initiated avalanche photodiode detection system. Ground testing and airborne validation plans are presented.

1.6μm DIAL System for Measurements of CO2 Concentration Profiles in the Atmosphere

NASA Astrophysics Data System (ADS)

Nagasawa, C.; Abo, M.; Shibata, Y.

2013-12-01

We have developed a direct detection 1.6 μm differential absorption lidar (DIAL) technique to perform range-resolved measurements of vertical CO2 concentration profiles in the atmosphere. Our 1.6 μm DIAL system has a 60 cm telescope for vertical measurement and a 25 cm scanning telescope for horizontal measurement. This 1.6 μm DIAL system is also available to measure CO2 concentration profiles for daytime by using narrow-band interference filters. The 1.6 μm DIAL measurement was achieved successfully the vertical CO2 profile up to 7 km altitude with an error less than 1.0 % by integration time of 30 minutes and vertical resolution of 300 - 600 m. The CO2 DIAL was also operated with the range-height indicator (RHI) mode, and the 2-D measurement provided inhomogeneity in the boundary layer. The vertical distribution of CO2 concentration from 2 km to 7 km altitude has been observed using two telescopes with different apertures. We hope to get the data of the CO2 concentration from lower altitude to 7 km at the same time. Since the change of signal intensity is larger near the ground, it is also important to the install the photon counter with the faster count rate to expand the dynamic range. The high speed counter and the telescope system make the dynamic range expand more than 10 times and the vertical distribution observation of CO2 concentration from 0.5 km to 7 km altitude is performed. This work was financially supported by the System Development Program for Advanced Measurement and Analysis of the Japan Science and Technology Agency. References Sakaizawa, D., C. Nagasawa, T. Nagai, M. Abo, Y. Shibata, H. Nagai, M. Nakazato, and T. Sakai, Development of a 1.6μm differential absorption lidar with a quasi-phase-matching optical parametric oscillator and photon-counting detector for the vertical CO2 profile, Applied Optics, Vol.48, No.4, pp. 748-757, 2009. Stephens, B. B. et al., Weak Northern and Strong Tropical Land Carbon Uptake from Vertical Profiles of Atmospheric CO2, Science 316, pp. 1732-1735, 2007.

Laser Sounder for Measuring Atmospheric CO2 Concentrations: Progress Toward Ascends

NASA Technical Reports Server (NTRS)

Abshire, J. B.; Kawa, S. R.; Riris, H.; Allan, G. R.; Sun, X.; Stephen, M. A.; Wilson, E.; Burris, J. F.; Mao, J.

2008-01-01

The next generation of space-based, active remote sensing instruments for measurement of tropospheric CO2 promises a capability to quantify global carbon sources and sinks at regional scales. Active (laser) methods will extend CO2 measurement coverage in time, space, and perhaps precision such that the underlying mechanisms for carbon exchange at the surface can be understood with .sufficient detail to confidently project the future of carbon-climate interaction and the influence of remediative policy actions. The recent Decadal Survey for Earth Science by the US National Research Council has recommended such a mission called the Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) for launch in 2013-2016. We have been developing a laser technique for measurement of tropospheric CO2 for a number of years. Our immediate goal is to develop and demonstrate the method and instrument technology that will permit measurements of the CO2 column abundance over a horizontal path and from aircraft at the few-ppmv level. Our longer-term goal is to demonstrate the required capabilities of the technique, develop a space mission approach, and design the instrument for an ASCENDS-type mission. Our approach is to use a dual channel laser absorption spectrometer (i.e., differential absorption in altimeter mode), which continuously measures from a near-polar circular orbit. We use several co-aligned tunable fiber laser transmitters allowing simultaneous measurement of the absorption from a CO2 line in the 1570 nm band, O2 extinction in the oxygen A-band (near 765 nm), and aerosol backscatter in the same measurement path. We measure the energy of the laser echoes at nadir reflected from land and water surfaces, day and night. The lasers have spectral widths much narrower than the gas absorption lines and are turned on and off the selected CO2 and O2 lines at kHz rates. The gas extinction and column densities for the CO2 and O2 gases are estimated from the ratio of the on and off-line singnals via the DIAL technique. We used pulsed laser signals, photon counting detectors, and time gating to isolate the laser returns from the surface, and to reject photons scattered from thin clouds and aerosols. High signal-to-noise ratios are required and the CO2 estimates can be sensitive to small drifts or other errors in the instrument, so the absorption estimates need to be quite stable for hours. We have constructed a breadboard version of the CO2 sensor that uses a low power fiber laser and a 20 cm diameter telescope. We have used it to make measurements of CO2 absorption in the laboratory and over 200-m to 2-km long open horizontal paths. These have been done in several sessions extending over multiple days, which allows us to assess the measurement stability and to compare absorption variations to readings from an external in situ CO2 sensor. We have also calculated characteristics of the technique for space including its expected measurement performance for different modulation types, and have performed an initial space mission accommodation study. We sill describe these results in the presentation.

Airborne Lidar for Simultaneous Measurement of Column CO2 and Water Vapor in the Atmosphere

NASA Technical Reports Server (NTRS)

Singh, Upendra N.; Petros, Mulugeta; Refaat, Tamer F.; Antill, Charles W.; Remus, Ruben; Yu, Jirong

2016-01-01

The 2-micron wavelength region is suitable for atmospheric carbon dioxide (CO2) measurements due to the existence of distinct absorption feathers for the gas at this particular wavelength. For more than 20 years, researchers at NASA Langley Research Center (LaRC) have developed several high-energy and high repetition rate 2-micron pulsed lasers. This paper will provide status and details of an airborne 2-micron triple-pulse integrated path differential absorption (IPDA) lidar. The development of this active optical remote sensing IPDA instrument is targeted for measuring both CO2 and water vapor (H2O) in the atmosphere from an airborne platform. This presentation will focus on the advancement of the 2-micron triple-pulse IPDA lidar development. Updates on the state-of-the-art triple-pulse laser transmitter will be presented including the status of seed laser locking, wavelength control, receiver telescope, detection system and data acquisition. Future plans for the IPDA lidar system for ground integration, testing and flight validation will also be presented.

1.6 μm DIAL Measurement and Back Trajectory Analysis of CO2 Concentration Profiles in the Lower-Atmosphere

NASA Astrophysics Data System (ADS)

Shibata, Y.; Nagasawa, C.; Abo, M.

2016-12-01

Carbon dioxide (CO2) is the primary greenhouse gas emitted through human activities. In addition to the ground level CO2 network, vertical CO2 concentration profiles also play an important role for the estimation of the carbon budget and global warming in the inversion method. Especially, for the detailed analysis of forest carbon dynamics and CO2 fluxes of urban area, vertical CO2 concentration profiles with high spatial and temporal resolution in the lower atmosphere have been conducted by a differential absorption lidar (DIAL). We have observed several vertical profiles of CO2 concentrations for nighttime and daytime from 0.25 to 2.5 km altitude with range resolution of 300 m and integration time of 1 hour. In order to extract information on the origin of the CO2 masses, one day back trajectories were calculated by using a three dimensional (3-D) atmospheric transport model. In many cases, CO2 low concentration layers of over 1.5km altitude were flown by westerly winds from the forest. In another case, high concentration layers of CO2 were flown from the urban areas. As the spectra of absorption lines of any molecules are influenced basically by the temperature in the atmosphere, laser beams of three wavelengths around a CO2 absorption spectrum are transmitted alternately to the atmosphere for simultaneous measurements of CO2 concentration and temperature profiles. Moreover, a few processing algorithms of CO2-DIAL are also performed for improvement of measurement accuracy. For computation of trajectories and drawing their figures, the JRA-25 data provided by the cooperative research project for the JRA-25 long-term reanalysis of the Japan Meteorological Agency (JMA) and the Central Research Institute of Electric Power Industry (CRIEPI) and the NIPR trajectory model (Tomikawa and Sato, 2005; http://firp-nitram.nipr.ac.jp) were used. This work was financially supported by the System Development Program for Advanced Measurement and Analysis of the Japan Science and Technology Agency.

Development and Evaluation of a High Sensitivity DIAL System for Profiling Atmospheric CO2

NASA Technical Reports Server (NTRS)

Ismail, Syed; Koch, Grady J.; Refaat, Tamer F.; Abedin, M. N.; Yu, Jirong; Singh, Upendra N.

2008-01-01

A ground-based 2-micron Differential Absorption Lidar (DIAL) CO2 profiling system for atmospheric boundary layer studies and validation of space-based CO2 sensors is being developed and tested at NASA Langley Research Center as part of the NASA Instrument Incubator Program. To capture the variability of CO2 in the lower troposphere a precision of 1-2 ppm of CO2 (less than 0.5%) with 0.5 to 1 km vertical resolution from near surface to free troposphere (4-5 km) is one of the goals of this program. In addition, a 1% (3 ppm) absolute accuracy with a 1 km resolution over 0.5 km to free troposphere (4-5 km) is also a goal of the program. This DIAL system leverages 2-micron laser technology developed under NASA's Laser Risk Reduction Program (LRRP) and other NASA programs to develop new solid-state laser technology that provides high pulse energy, tunable, wavelength-stabilized, and double-pulsed lasers that are operable over pre-selected temperature insensitive strong CO2 absorption lines suitable for profiling of lower tropospheric CO2. It also incorporates new high quantum efficiency, high gain, and relatively low noise phototransistors, and a new receiver/signal processor system to achieve high precision DIAL measurements. This presentation describes the capabilities of this system for atmospheric CO2 and aerosol profiling. Examples of atmospheric measurements in the lidar and DIAL mode will be presented.

LTCC-based differential photo acoustic cell for ppm gas sensing

NASA Astrophysics Data System (ADS)

Karioja, P.; Keränen, K.; Kautio, K.; Ollila, J.; Heikkinen, M.; Kauppinen, I.; Kuusela, T.; Matveev, B.; McNie, M. E.; Jenkins, R. M.; Palve, J.

2010-04-01

Silicon MEMS cantilever-based photoacoustic technology allows for the sensing of ultra low gas concentrations with very wide dynamic range. The sensitivity enhancement is achieved with a cantilever microphone system in which the cantilever displacement is probed with an optical interferometer providing a pico-meter resolution. In the gas sensor, the silicon cantilever microphone is placed in a two-chamber differential gas cell. By monitoring differential pressure changes between the two chambers, the differential cell operates as a differential infra-red detector for optical absorption signals through a measurement and reference path. The differential pressure signal is proportional to gas concentration in the optical measurement path. We have designed, implemented and tested a differential photo acoustic gas cell based on Low Temperature Co-fired Ceramic (LTCC) multilayer substrate technology. Standard LTCC technology enables implementation of 2.5D structures including holes, cavities and channels into the electronic substrate. The implemented differential photoacoustic gas cell structure includes two 10 mm long cylindrical cells, diameter of 2.4 mm. Reflectance measurements of the cell showed that reflectivity of the substrate material can be improved by a factor 15 - 90 in the 3 - 8 μm spectral region using gold or silver paste coatings. A transparent window is required in the differential gas cell structure in order to probe the displacement of the silicon cantilever. The transparent sapphire window was sealed to the LTCC substrate using two methods: screen printed Au80/Sn20 solder paste and pre-attached glass solder paste (Diemat DM2700P/H848). Both methods were shown to provide hermetic sealing of sapphire windows to LTCC substrate. The measured He-leak rate for the 10 sealed test samples implemented using glass paste were less than 2.0 ×10-9 atm×cm3/s, which meets the requirement for the leak rate according to MIL-STD 883. The achieved hermetic level suggests that the proof-of-principle packaging demonstrator paves the way for implementing a novel differential photoacoustic gas cell for a future miniature gas sensor module. The future module consisting of a sample gas cell and immersion lens IR-LEDs together with interferometric probing of the cantilever microphone is expected to be capable of measuring ultra low concentrations of a wide range of gases with their fundamental absorption bands at 3 - 7 μm wavelength, such as CO, CO2 and CH4.

Determination of the heat of hydride formation/decomposition by high-pressure differential scanning calorimetry (HP-DSC).

PubMed

Rongeat, Carine; Llamas-Jansa, Isabel; Doppiu, Stefania; Deledda, Stefano; Borgschulte, Andreas; Schultz, Ludwig; Gutfleisch, Oliver

2007-11-22

Among the thermodynamic properties of novel materials for solid-state hydrogen storage, the heat of formation/decomposition of hydrides is the most important parameter to evaluate the stability of the compound and its temperature and pressure of operation. In this work, the desorption and absorption behaviors of three different classes of hydrides are investigated under different hydrogen pressures using high-pressure differential scanning calorimetry (HP-DSC). The HP-DSC technique is used to estimate the equilibrium pressures as a function of temperature, from which the heat of formation is derived. The relevance of this procedure is demonstrated for (i) magnesium-based compounds (Ni-doped MgH2), (ii) Mg-Co-based ternary hydrides (Mg-CoHx) and (iii) Alanate complex hydrides (Ti-doped NaAlH4). From these results, it can be concluded that HP-DSC is a powerful tool to obtain a good approximation of the thermodynamic properties of hydride compounds by a simple and fast study of desorption and absorption properties under different pressures.

InGaAsSb Detectors' Characterization for 2-Micron CO2 Lidar/DIAL Applications

NASA Technical Reports Server (NTRS)

Refaat, Tamer F.; Abedin, M. Nurul; Koch, Grady J.; Singh, Upendra N.

2003-01-01

Recent interest in monitoring atmospheric CO2 focuses attention on infrared remote sensing using the 2-micron lidar/differential absorption lidar (DIAL) technique. Quantum detectors are critical components in this technique, and many research efforts concentrate on developing such devices for the 2-micron wavelength. Characterization results of InGaAsSb quantum detectors for the 2-micron wavelength range are presented, including experimental setup and procedure. Detectors are prototype devices manufactured by using separate absorption and multiplication (SAM) structures. Characterization experiments include V-I measurements, spectral response and its variation with bias voltage and temperature, noise measurements, noise-equivalent-power (NEP) and detectivity calculations, and signal-to-noise ratio (SNR) estimation. A slight increase in the output signal occurred with increased bias voltage and was associated with a noise level increase. Cooling down the detectors reduces noise and shifts the cutoff wavelength to shorter values. Further improvement in the design and manufacturing process, by increasing the device gain and lowering its noise level, is necessary to meet the required CO2 lidar/DIAL specifications.

Optical Measurement of Radiocarbon below Unity Fraction Modern by Linear Absorption Spectroscopy.

PubMed

Fleisher, Adam J; Long, David A; Liu, Qingnan; Gameson, Lyn; Hodges, Joseph T

2017-09-21

High-precision measurements of radiocarbon ( 14 C) near or below a fraction modern 14 C of 1 (F 14 C ≤ 1) are challenging and costly. An accurate, ultrasensitive linear absorption approach to detecting 14 C would provide a simple and robust benchtop alternative to off-site accelerator mass spectrometry facilities. Here we report the quantitative measurement of 14 C in gas-phase samples of CO 2 with F 14 C < 1 using cavity ring-down spectroscopy in the linear absorption regime. Repeated analysis of CO 2 derived from the combustion of either biogenic or petrogenic sources revealed a robust ability to differentiate samples with F 14 C < 1. With a combined uncertainty of 14 C/ 12 C = 130 fmol/mol (F 14 C = 0.11), initial performance of the calibration-free instrument is sufficient to investigate a variety of applications in radiocarbon measurement science including the study of biofuels and bioplastics, illicitly traded specimens, bomb dating, and atmospheric transport.

A Lidar for Making Range Resolved CO2 Measurements within the Planetary Boundary Layer

NASA Technical Reports Server (NTRS)

Burris, John; Riris, Haris; Andrews, Arlyn; Krainak, Mike; Sun, Xiaoli; Abshire, Jim; Colarco, Amelia; Heaps, William

2006-01-01

A ground based differential absorption lidar is under development at NASA's Goddard Space Flight Center to make range resolved measurements of CO2 within the planetary boundary layer. This is a direct detection lidar designed for both photon counting and analog use. Technology being developed for this instrument will be discussed including efforts in fiber lasers, optical parametric amplifiers and both InGaAs and HgCdTe solid-state detectors. The capabilities of this system are investigated and preliminary results presented.

Pulsed 2-micron Laser Transmitter For Carbon Dioxide Sensing From Space

NASA Astrophysics Data System (ADS)

Singh, U. N.; Yu, J.; Bai, Y.; Petros, M.

2011-12-01

Carbon dioxide (CO2) has been recognized as one of the most important greenhouse gases. It is essential for the study of global warming to accurately measure the CO2 concentration in the atmosphere and continuously record its variation. Studies of the carbon cycle are limited by the tools available to precisely measure CO2 concentrations by remote sensing. Active sensing, using the Integrated Path Differential Absorption (IPDA) approach, permits measurements day and night, at all latitudes and seasons. The development of a high pulse energy 2-μm laser transmitter for high-precision CO2 measurements from space leverages years of NASA investment in solid-state laser technology. Under NASA Laser Risk Reduction Program, funded by Earth Science Technology Office, researchers at NASA Langley Research Center developed an injection seeded, high repetition rate, Q-switched Ho:YLF laser transmitter for CO2 Differential Absorption Lidar/IPDA (profile/column) measurements from ground and airborne platforms. This master-slave laser system has high optical-to-optical efficiency and seeding success rate. NASA LaRC's 2-micron pulsed laser transmitter possesses advantages over current passive and CW active sensors. First, the pulsed format provides a built-in means for determining range to the scattering target and effectively filtering out the scattering from thin clouds and aerosols, thus eliminating a source of measurement bias. Second, by concentrating the laser energy into a pulse, sufficient backscatter signal strength can be obtained from aerosol scattering rather than relying on a hard target at a known distance. Third, the absorption line at the 2.05 μm band is ideally suited for the CO2 concentration measurement. In particular, the weighting function of 2 μm is optimum for measurement in the lower troposphere where the sources and sinks of CO2 are located. The planned laser transmitter development will lead to a Tm:Fiber pumped Ho:YLF laser transmitter capable of delivering 65 mJ at 50 Hz at on-line wavelength and 50 mJ at 50 Hz at off-line wavelength. The planned laser technology development and performance capabilities are a major step forward in the laser transmitter requirements called out in recent comprehensive system studies, e.g., the European Space Agency (ESA) exploration mission studies, A-SCOPE, for future CO2 column density measurements from space. The planned laser technology development is relevant to NASA's earth science priorities, such as NASA ASCENDS mission for space-based CO2 column density measurements. This presentation will provide an overview of the current status of laser transmitter development and describe future technology development to meet the transmitter requirement for a space-based column averaged measurement of CO2 concentration.

Space-borne remote sensing of CO2 by IPDA lidar with heterodyne detection: random error estimation

NASA Astrophysics Data System (ADS)

Matvienko, G. G.; Sukhanov, A. Y.

2015-11-01

Possibilities of measuring the CO2 column concentration by spaceborne integrated path differential lidar (IPDA) signals in the near IR absorption bands are investigated. It is shown that coherent detection principles applied in the nearinfrared spectral region promise a high sensitivity for the measurement of the integrated dry air column mixing ratio of the CO2. The simulations indicate that for CO2 the target observational requirements (0.2%) for the relative random error can be met with telescope aperture 0.5 m, detector bandwidth 10 MHz, laser energy per impulse 0.3 mJ and averaging 7500 impulses. It should also be noted that heterodyne technique allows to significantly reduce laser power and receiver overall dimensions compared to direct detection.

Feasibility study of a space-based high pulse energy 2  μm CO2 IPDA lidar.

PubMed

Singh, Upendra N; Refaat, Tamer F; Ismail, Syed; Davis, Kenneth J; Kawa, Stephan R; Menzies, Robert T; Petros, Mulugeta

2017-08-10

Sustained high-quality column carbon dioxide (CO 2 ) atmospheric measurements from space are required to improve estimates of regional and continental-scale sources and sinks of CO 2 . Modeling of a space-based 2 μm, high pulse energy, triple-pulse, direct detection integrated path differential absorption (IPDA) lidar was conducted to demonstrate CO 2 measurement capability and to evaluate random and systematic errors. Parameters based on recent technology developments in the 2 μm laser and state-of-the-art HgCdTe (MCT) electron-initiated avalanche photodiode (e-APD) detection system were incorporated in this model. Strong absorption features of CO 2 in the 2 μm region, which allows optimum lower tropospheric and near surface measurements, were used to project simultaneous measurements using two independent altitude-dependent weighting functions with the triple-pulse IPDA. Analysis of measurements over a variety of atmospheric and aerosol models using a variety of Earth's surface target and aerosol loading conditions were conducted. Water vapor (H 2 O) influences on CO 2 measurements were assessed, including molecular interference, dry-air estimate, and line broadening. Projected performance shows a <0.35  ppm precision and a <0.3  ppm bias in low-tropospheric weighted measurements related to column CO 2 optical depth for the space-based IPDA using 10 s signal averaging over the Railroad Valley (RRV) reference surface under clear and thin cloud conditions.

Semi-Empirical Validation of the Cross-Band Relative Absorption Technique for the Measurement of Molecular Mixing Ratios

NASA Technical Reports Server (NTRS)

Pliutau, Denis; Prasad, Narasimha S

2013-01-01

Studies were performed to carry out semi-empirical validation of a new measurement approach we propose for molecular mixing ratios determination. The approach is based on relative measurements in bands of O2 and other molecules and as such may be best described as cross band relative absorption (CoBRA). . The current validation studies rely upon well verified and established theoretical and experimental databases, satellite data assimilations and modeling codes such as HITRAN, line-by-line radiative transfer model (LBLRTM), and the modern-era retrospective analysis for research and applications (MERRA). The approach holds promise for atmospheric mixing ratio measurements of CO2 and a variety of other molecules currently under investigation for several future satellite lidar missions. One of the advantages of the method is a significant reduction of the temperature sensitivity uncertainties which is illustrated with application to the ASCENDS mission for the measurement of CO2 mixing ratios (XCO2). Additional advantages of the method include the possibility to closely match cross-band weighting function combinations which is harder to achieve using conventional differential absorption techniques and the potential for additional corrections for water vapor and other interferences without using the data from numerical weather prediction (NWP) models.

Cooperative CO2 Absorption Isotherms from a Bifunctional Guanidine and Bifunctional Alcohol.

PubMed

Steinhardt, Rachel; Hiew, Stanley C; Mohapatra, Hemakesh; Nguyen, Du; Oh, Zachary; Truong, Richard; Esser-Kahn, Aaron

2017-12-27

Designing new liquids for CO 2 absorption is a challenge in CO 2 removal. Here, achieving low regeneration energies while keeping high selectivity and large capacity are current challenges. Recent cooperative metal-organic frameworks have shown the potential to address many of these challenges. However, many absorbent systems and designs rely on liquid capture agents. We present herein a liquid absorption system which exhibits cooperative CO 2 absorption isotherms. Upon introduction, CO 2 uptake is initially suppressed, followed by an abrupt increase in absorption. The liquid consists of a bifunctional guanidine and bifunctional alcohol, which, when dissolved in bis(2-methoxyethyl) ether, forms a secondary viscous phase within seconds in response to increases in CO 2 . The precipitation of this second viscous phase drives CO 2 absorption from the gas phase. The isotherm of the bifunctional system differs starkly from the analogous monofunctional system, which exhibits limited CO 2 uptake across the same pressure range. In our system, CO 2 absorption is strongly solvent dependent. In DMSO, both systems exhibit hyperbolic isotherms and no precipitation occurs. Subsequent 1 H NMR experiments confirmed the formation of distinct alkylcarbonate species having either one or two molecules of CO 2 bound. The solvent and structure relationships derived from these results can be used to tailor new liquid absorption systems to the conditions of a given CO 2 separation process.

Measurement of Atmospheric CO2 Column Concentrations to Cloud Tops With a Pulsed Multi-Wavelength Airborne Lidar

NASA Technical Reports Server (NTRS)

Mao, Jianping; Ramanathan, Anand; Abshire, James B.; Kawa, Stephan R.; Riris, Haris; Allan, Graham R.; Rodriguez, Michael R.; Hasselbrack, William E.; Sun, Xiaoli; Numata, Kenji;

Measurement of atmospheric CO2 column concentrations to cloud tops with a pulsed multi-wavelength airborne lidar

NASA Astrophysics Data System (ADS)

Mao, Jianping; Ramanathan, Anand; Abshire, James B.; Kawa, Stephan R.; Riris, Haris; Allan, Graham R.; Rodriguez, Michael; Hasselbrack, William E.; Sun, Xiaoli; Numata, Kenji; Chen, Jeff; Choi, Yonghoon; Yang, Mei Ying Melissa

2018-01-01

We have measured the column-averaged atmospheric CO2 mixing ratio to a variety of cloud tops by using an airborne pulsed multi-wavelength integrated-path differential absorption (IPDA) lidar. Airborne measurements were made at altitudes up to 13 km during the 2011, 2013 and 2014 NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) science campaigns flown in the United States West and Midwest and were compared to those from an in situ sensor. Analysis of the lidar backscatter profiles shows the average cloud top reflectance was ˜ 5 % for the CO2 measurement at 1572.335 nm except to cirrus clouds, which had lower reflectance. The energies for 1 µs wide laser pulses reflected from cloud tops were sufficient to allow clear identification of CO2 absorption line shape and then to allow retrievals of atmospheric column CO2 from the aircraft to cloud tops more than 90 % of the time. Retrievals from the CO2 measurements to cloud tops had minimal bias but larger standard deviations when compared to those made to the ground, depending on cloud top roughness and reflectance. The measurements show this new capability helps resolve CO2 horizontal and vertical gradients in the atmosphere. When used with nearby full-column measurements to ground, the CO2 measurements to cloud tops can be used to estimate the partial-column CO2 concentration below clouds, which should lead to better estimates of surface carbon sources and sinks. This additional capability of the range-resolved CO2 IPDA lidar technique provides a new benefit for studying the carbon cycle in future airborne and space-based CO2 missions.

Production of dense plasmas in a hypocycloidal pinch apparatus

NASA Technical Reports Server (NTRS)

Lee, J. H.; Mcfarland, D. R.; Hohl, F.

1977-01-01

A high-power pinch apparatus consisting of disk electrodes was developed, and diagnostic measurements to study its mechanism of dense plasma production have been made. The collapse fronts of the current sheets are well organized, and dense plasma foci are produced on the axis with radial stability in excess of 5 microsec. A plasma density greater than 10 to the 18th power per cu cm is determined with Stark broadening and CO2 laser absorption. Essentially complete absorption of a high-energy CO2 laser beam has been observed. A plasma temperature of approximately 1 keV is measured with differential transmission of soft X-rays through thin foils. The advantages of this apparatus over the coaxial plasma focus are improvements in (1) plasma volume, (2) stability, (3) containment time, (4) access to additional heating by laser or electron beams, and (5) the possibility of scaling up to a multiple array for high-power operation.

Dense plasma focus production in a hypocycloidal pinch

NASA Technical Reports Server (NTRS)

Lee, J. H.; Mcfarland, D. R.; Hohl, F.

1975-01-01

A type of high-power pinch apparatus consisting of disk electrodes was developed, and diagnostic measurements to study its mechanism of dense plasma production were made. The collapse fronts of the current sheets are well organized, and dense plasma focuses are produced on the axis with radial stability in excess of 5 microns. A plasma density greater than 10 to the 18th power/cubic cm was determined with Stark broadening and CO2 laser absorption. A plasma temperature of approximately 1 keV was measured with differential transmission of soft X-rays through thin foils. Essentially complete absorption of a high-energy CO2 laser beam was observed. The advantages of this apparatus over the coaxial plasma focus are in (1) the plasma volume, (2) the stability, (3) the containment time, (4) the easy access to additional heating by laser or electron beams, and (5) the possibility of scaling up to a multiple array for high-power operation.

Space-based active optical remote sensing of carbon dioxide column using high-energy two-micron pulsed ipda lidar

NASA Astrophysics Data System (ADS)

Singh, Upendra N.; Refaat, Tamer F.; Ismail, Syed; Petros, Mulugeta; Davis, Kenneth J.; Kawa, Stephan R.; Menzies, Robert T.

2018-04-01

Modeling of a space-based high-energy 2-μm triple-pulse Integrated Path Differential Absorption (IPDA) lidar was conducted to demonstrate carbon dioxide (CO2) measurement capability and to evaluate random and systematic errors. A high pulse energy laser and an advanced MCT e-APD detector were incorporated in this model. Projected performance shows 0.5 ppm precision and 0.3 ppm bias in low-tropospheric column CO2 mixing ratio measurements from space for 10 second signal averaging over Railroad Valley (RRV) reference surface.

Development of differential absorption lidar (DIAL) for detection of CO2, CH4 and PM in Alberta

NASA Astrophysics Data System (ADS)

Wojcik, Michael; Crowther, Blake; Lemon, Robert; Valupadas, Prasad; Fu, Long; Leung, Bonnie; Yang, Zheng; Huda, Quamrul; Chambers, Allan

2005-05-01

Rapid expansion of the oil and gas industry in Alberta, including the oil sands, has challenged the Alberta Government to keep pace in its efforts to monitor and mitigate the environmental impacts of development. The limitations of current monitoring systems has pushed the provincial government to seek out advanced sensing technologies such as satellite imagery and laser based sensors. The Space Dynamics Laboratory (SDL) of Utah State University, in cooperation with Alberta Environmental Monitoring, Evaluation and Reporting Agency (AEMERA), has developed North America's first mobile differential absorption lidar (DIAL) system designed specifically for emissions measurement. This instrument is housed inside a 36' trailer which allows for mobility to travel across Alberta to characterize source emissions and to locate fugitive leaks. DIAL is capable of measuring concentrations for carbon dioxide (CO2) and methane (CH4) at ranges of up to 3 km with a spatial resolution of 10 meters. DIAL can map both CO2 and CH4, as well as particulate matter (PM) in a linear fashion; by scanning the laser beam in both azimuth and elevation DIAL can create images of emissions in two dimensions. DIAL imagery may be used to understand and control production practices, characterize source emissions, determine emission factors, locate fugitive leaks, assess plume dispersion, and confirm air dispersion modeling. A system overview of the DIAL instrument and some representative results will be discussed.

Differential Absorption Lidar (DIAL) in Alberta: A New Remote Sensing Tool for Wide Area Measurement of Particulates, CO2, and CH4 Emissions from Energy Extraction and Production Sites

NASA Astrophysics Data System (ADS)

Wojcik, M.; Lemon, R.; Crowther, B. G.; Valupadas, P.; Fu, L.; Yang, Z.; Huda, Q.; Leung, B.; Chambers, A.

2014-12-01

Alberta Environmental Monitoring, Evaluation and Reporting Agency (AEMERA) in cooperation with the Space Dynamics Laboratory (SDL) of Utah State University, have developed a mobile DIAL sensor designed specifically for particle, CO2 and CH4 emissions measurement. Rapid expansion of the oil and gas industry in Alberta, including the oil sands, has challenged the Alberta Government to keep pace in its efforts to monitor and mitigate the environmental impacts of development. The limitations of current monitoring systems has pushed the provincial government to seek out advanced sensing technologies such as differential absorption lidar (DIAL) to help assess the impact of energy development and industrial operations. This instrument is housed inside a 36' trailer and can be quickly staged and used to characterize source emissions and to locate fugitive leaks. DIAL is capable of measuring concentrations for carbon dioxide (CO2) and methane (CH4) at ranges of up to 3 km with a spatial resolution of 1.5 m. DIAL can map both CO2 and CH4, as well as particulate matter (PM) in a linear fashion; by scanning the laser beam in both azimuth and elevation, DIAL can create images of emissions concentrations and ultimately can be used to determine emission factors, locate fugitive leaks, assess plume dispersion and confirm air dispersion modeling. The DIAL system has been deployed at a landfill, a coal-fired power plant, and an oil sands production area. A system overview of the DIAL instrument and recent results will be discussed.

Development of Laser, Detector, and Receiver Systems for an Atmospheric CO2 Lidar Profiling System

NASA Technical Reports Server (NTRS)

Ismail, Syed; Koch, Grady; Abedin, Nurul; Refaat, Tamer; Rubio, Manuel; Singh, Upendra

2008-01-01

A ground-based Differential Absorption Lidar (DIAL) is being developed with the capability to measure range-resolved and column amounts of atmospheric CO2. This system is also capable of providing high-resolution aerosol profiles and cloud distributions. It is being developed as part of the NASA Earth Science Technology Office s Instrument Incubator Program. This three year program involves the design, development, evaluation, and fielding of a ground-based CO2 profiling system. At the end of a three-year development this instrument is expected to be capable of making measurements in the lower troposphere and boundary layer where the sources and sinks of CO2 are located. It will be a valuable tool in the validation of NASA Orbiting Carbon Observatory (OCO) measurements of column CO2 and suitable for deployment in the North American Carbon Program (NACP) regional intensive field campaigns. The system can also be used as a test-bed for the evaluation of lidar technologies for space-application. This DIAL system leverages 2-micron laser technology developed under a number of NASA programs to develop new solid-state laser technology that provides high pulse energy, tunable, wavelength-stabilized, and double-pulsed lasers that are operable over pre-selected temperature insensitive strong CO2 absorption lines suitable for profiling of lower tropospheric CO2. It also incorporates new high quantum efficiency, high gain, and relatively low noise phototransistors, and a new receiver/signal processor system to achieve high precision DIAL measurements.

Stratospheric CH4 and CO2 profiles derived from SCIAMACHY solar occultation measurements

NASA Astrophysics Data System (ADS)

Noël, S.; Bramstedt, K.; Hilker, M.; Liebing, P.; Plieninger, J.; Reuter, M.; Rozanov, A.; Bovensmann, H.; Burrows, J. P.

2015-11-01

Stratospheric profiles of methane (CH4) and carbon dioxide (CO2) have been derived from solar occultation measurements of the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY). The retrieval is performed using a method called "Onion Peeling DOAS" (ONPD) which combines an onion peeling approach with a weighting function DOAS (Differential Optical Absorption Spectroscopy) fit. By use of updated pointing information and optimisation of the data selection and of the retrieval approach the altitude range for reasonable CH4 could be extended to about 17 to 45 km. Furthermore, the quality of the derived CO2 has been assessed such that now the first stratospheric profiles of CO2 from SCIAMACHY are available. Comparisons with independent data sets yield an estimated accuracy of the new SCIAMACHY stratospheric profiles of about 5-10 % for CH4 and 2-3 % for CO2. The accuracy of the products is currently mainly restricted by the appearance of unexpected vertical oscillations in the derived profiles which need further investigation. Using the improved ONPD retrieval, CH4 and CO2 stratospheric data sets covering the whole SCIAMACHY time series (August 2002-April 2012) and the latitudinal range between about 50 and 70° N have been derived. Based on these time series, CH4 and CO2 trends have been estimated, which are in reasonable agreement with total column trends for these gases. This shows that the new SCIAMACHY data sets can provide valuable information about the stratosphere.

Can CO2 Turbulent Flux Be Measured by Lidar? A Preliminary Study

NASA Technical Reports Server (NTRS)

Gilbert, Fabien; Koch, Grady; Beyon, Jeffrey Y.; Hilton, Timothy W.; Davis, Kenneth J.; Andrews, Arlyn; Flamant, Pierre H.; Singh, Upendra N.

2011-01-01

The vertical profiling ofCO2 turbulent fluxes in the atmospheric boundary layer (ABL) is investigated using a coherent differential absorption lidar (CDIAL) operated nearby a tall tower in Wisconsin during June 2007. A CDIAL can perform simultaneous range-resolved CO2 DIAL and velocity measurements. The lidar eddy covariance technique is presented. The aims of the study are (i) an assessment of performance and current limitation of available CDIAL for CO2 turbulent fluxes and (ii) the derivation of instrument specifications to build a future CDIAL to perform accurate range-resolved CO2 fluxes. Experimental lidar CO2 mixing ratio and vertical velocity profiles are successfully compared with in situ sensors measurements. Time and space integral scales of turbulence in the ABL are addressed that result in limitation for time averaging and range accumulation. A first attempt to infer CO2 fluxes using an eddy covariance technique with currently available 2-mm CDIAL dataset is reported.

Sugar acetates as CO2-philes: molecular interactions and structure aspects from absorption measurement using quartz crystal microbalance.

PubMed

Ma, Shao-Ling; Wu, You-Ting; Hurrey, Michael L; Wallen, Scott L; Grant, Christine S

2010-03-25

Sugar acetates, recognized as attractive CO(2)-philic compounds, have potential uses as pharmaceutical excipients, controlled release agents, and surfactants for microemulsion systems in CO(2)-based processes. This study focuses on the quantitative examination of absorption of high pressure CO(2) into these sugar derivatives using quartz crystal microbalance (QCM) as a detector. In addition to the absorption measurement, the QCM is initially found to be able to detect the CO(2)-induced deliquescence of sugar acetates, and the CO(2) pressure at which the deliquescence happens depends on several influencing factors such as the temperature and thickness of the film. The CO(2) absorption in alpha-D-glucose pentaacetate (Ac-alpha-GLU) is revealed to be of an order of magnitude larger in comparison with its anomer Ac-beta-GLU, whereas alpha-D-galactose pentaacetate (Ac-alpha-GAL) absorbs CO(2) less than Ac-alpha-GLU due to the steric-hindrance between the acetyl groups on the anomeric and C4 carbons, implying the significant importance of the molecular structure and configuration of sugar acetates on the absorption. The effects of molecular size and acetyl number of sugar acetates on the CO(2) absorption are evaluated and the results indicate that the conformation and packing of crystalline sugar acetate as well as the accessibility of the acetyls are also vital for the absorption of CO(2). It is additionally found that a CO(2)-induced change in the structure from a crystalline system to an amorphous system results in an order of magnitude increase in CO(2) absorption. Further investigation illustrates the interaction strength between sugar acetates and CO(2) by calculating the thermodynamic parameters such as Henry's law constant, enthalpy and entropy of dissolution from the determined CO(2) absorption. Experiments and calculations demonstrate that sugar acetates exhibit high CO(2) absorption, as at least comparable to ionic liquids. Since the ionic liquids have potential uses in the separation of acidic gases, it is evident from this study that sugar acetates could be used as possible materials for CO(2) separation.

Step-scan T cell-based differential Fourier transform infrared photoacoustic spectroscopy (DFTIR-PAS) for detection of ambient air contaminants

NASA Astrophysics Data System (ADS)

Liu, Lixian; Mandelis, Andreas; Huan, Huiting; Melnikov, Alexander

2016-10-01

A step-scan differential Fourier transform infrared photoacoustic spectroscopy (DFTIR-PAS) using a commercial FTIR spectrometer was developed theoretically and experimentally for air contaminant monitoring. The configuration comprises two identical, small-size and low-resonance-frequency T cells satisfying the conflicting requirements of low chopping frequency and limited space in the sample compartment. Carbon dioxide (CO2) IR absorption spectra were used to demonstrate the capability of the DFTIR-PAS method to detect ambient pollutants. A linear amplitude response to CO2 concentrations from 100 to 10,000 ppmv was observed, leading to a theoretical detection limit of 2 ppmv. The differential mode was able to suppress the coherent noise, thereby imparting the DFTIR-PAS method with a better signal-to-noise ratio and lower theoretical detection limit than the single mode. The results indicate that it is possible to use step-scan DFTIR-PAS with T cells as a quantitative method for high sensitivity analysis of ambient contaminants.

Laser Sounder for Global Measurement of CO2 Concentrations in the Troposphere from Space

NASA Technical Reports Server (NTRS)

Abshire, James B.; Riris, Haris; Kawa, S. Randy; Sun, Xiaoli; Chen, Jeffrey; Stephen, Mark A.; Collatz, G. James; Mao, Jianping; Allan, Graham

2007-01-01

Measurements of tropospheric CO2 abundance with global-coverage, a few hundred km spatial and monthly temporal resolution are needed to quantify processes that regulate CO2 storage by the land and oceans. The Orbiting Carbon Observatory (OCO) is the first space mission focused on atmospheric CO2 for measuring total column CO, and O2 by detecting the spectral absorption in reflected sunlight. The OCO mission is an essential step, and will yield important new information about atmospheric CO2 distributions. However there are unavoidable limitations imposed by its measurement approach. These include best accuracy only during daytime at moderate to high sun angles, interference by cloud and aerosol scattering, and limited signal from CO2 variability in the lower tropospheric CO2 column. We have been developing a new laser-based technique for the remote measurement of the tropospheric CO2 concentrations from orbit. Our initial goal is to demonstrate a lidar technique and instrument technology that will permit measurements of the CO2 column abundance in the lower troposphere from aircraft. Our final goal is to develop a space instrument and mission approach for active measurements of the CO2 mixing ratio at the 1-2 ppmv level. Our technique is much less sensitive to cloud and atmospheric scattering conditions and would allow continuous measurements of CO2 mixing ratio in the lower troposphere from orbit over land and ocean surfaces during day and night. Our approach is to use the 1570nm CO2 band and a 3-channel laser absorption spectrometer (i.e. lidar used an altimeter mode), which continuously measures at nadir from a near polar circular orbit. The approach directs the narrow co-aligned laser beams from the instrument's lasers toward nadir, and measures the energy of the laser echoes reflected from land and water surfaces. It uses several tunable fiber laser transmitters which allowing measurement of the extinction from a single selected CO2 absorption line in the 1570 nm band. This band is free from interference from other gases and has temperature insensitive absorption lines. During the measurement the lasers are tuned on- and off- a selected CO2 line near 1572 nm and a selected O2 line near 768 nm in the Oxygen A band at kHz rates. The lasers use tunable diode seed lasers followed by fiber amplifiers, and have spectral widths much narrower than the gas absorption lines. The receiver uses a 1-m diameter telescope and photon counting detectors and measures the background light and energies of the laser echoes from the surface. The extinction and column densities for the CO2 and O2 gases are estimated from the ratio of the on and offline surface echo via the differential optical absorption technique. Our technique rapidly alternates between several on-line wavelengths set to the sides of the selected gas absorption lines. It exploits the atmospheric pressure broadening of the lines to weight the measurement sensitivity to the atmospheric column below 5 km. This maximizes sensitivity to CO2 in the boundary layer, where variations caused by surface sources and sinks are largest. Simultaneous measurements of O2 column will use an identical approach with an O2 line. Thee laser frequencies are tunable and have narrow (MHz) line widths. In combination with sensitive photon counting detectors these enables much higher spectral resolution and precision than is possible with passive spectrometer. 1aser backscatter profiles are also measured, which permits identifying measurements made to cloud tops and through aerosol layers. The measurement approach using lasers in common-nadir-zenith path allows retrieving CO2 column mixing ratios in the lower troposphere irrespective of sun angle. Pulsed laser signals, time gated receiver and a narrow receiver field-of-view are used to isolate the surface laser echo signals and to exclude photons scattered from clouds and aerosols. Nonetheless, the optical absorption change due to a change of a few ppO2 is small, <1 % which makes achieving the needed measurement sensitivities and stabilities quite challenging. Measurement SNRs and stabilities of >600:1 are needed to estimate CO2 mixing ratio at the 1-2 ppm level. We have calculated characteristics of the technique and have demonstrated aspects of the laser, detector and receiver approaches in th e laboratory We have also measured O2 in an absorption cell, and made C02 measurements over a 400 m long (one way) horizontal path using a sensor breadboard. We will describe these and more details of our approach in the paper.

Airborne Measurements of Atmospheric Methane Using Pulsed Laser Transmitters

NASA Technical Reports Server (NTRS)

Numata, Kenji; Riris, Haris; Wu, Stewart; Gonzalez, Brayler; Rodriguez, Michael; Hasselbrack, William; Fahey, Molly; Yu, Anthony; Stephen, Mark; Mao, Jianping;

Development of a carbonate absorption-based process for post-combustion CO2 capture: The role of biocatalyst to promote CO2 absorption rate

USGS Publications Warehouse

Lu, Y.; Ye, X.; Zhang, Z.; Khodayari, A.; Djukadi, T.

2011-01-01

An Integrated Vacuum Carbonate Absorption Process (IVCAP) for post-combustion carbon dioxide (CO2) capture is described. IVCAP employs potassium carbonate (PC) as a solvent, uses waste or low quality steam from the power plant for CO2 stripping, and employs a biocatalyst, carbonic anhydrase (CA) enzyme, for promoting the CO2 absorption into PC solution. A series of experiments were performed to evaluate the activity of CA enzyme mixed in PC solutions in a stirred tank reactor system under various temperatures, CA dosages, CO2 loadings, CO2 partial pressures, and the presence of major flue gas contaminants. It was demonstrated that CA enzyme is an effective biocatalyst for CO2 absorption under IVCAP conditions. ?? 2011 Published by Elsevier Ltd.

Temperature and pressure dependence of dichloro-difluoromethane (CF2C12) absorption coefficients for CO2 waveguide laser radiation

NASA Technical Reports Server (NTRS)

Harward, C. N.

1977-01-01

Measurements were performed to determine the pressure and temperature dependence of CFM-12 absorption coefficients for CO2 waveguide laser radiation. The absorption coefficients of CFM-12 for CO2 waveguide laser radiation were found to have no spectral structure within small spectral bandwidths around the CO2 waveguide laser lines in the CO2 spectral band for pressures above 20 torr. All of the absorption coefficients for the CO2 laser lines studied are independent of pressure above 100 torr, except for the P(36) laser CO2 spectral band. The absorption coefficients associated with the P(42) line in the same band showed the greatest change with temperature, and it also has the largest value of all the lines studied.

Encapsulation of Ionic Liquids with an Aprotic Heterocyclic Anion (AHA-IL) for CO2 Capture: Preserving the Favorable Thermodynamics and Enhancing the Kinetics of Absorption.

PubMed

Moya, Cristian; Alonso-Morales, Noelia; de Riva, Juan; Morales-Collazo, Oscar; Brennecke, Joan F; Palomar, Jose

2018-03-08

The performance of an ionic liquid with an aprotic heterocyclic anion (AHA-IL), trihexyl(tetradecyl)phosphonium 2-cyanopyrrolide ([P 66614 ][2-CNPyr]), for CO 2 capture has been evaluated considering both the thermodynamics and the kinetics of the phenomena. Absorption gravimetric measurements of the gas-liquid equilibrium isotherms of CO 2 -AHA-IL systems were carried out from 298 to 333 K and at pressures up to 15 bar, analyzing the role of both chemical and physical absorption phenomena in the overall CO 2 solubility in the AHA-IL, as has been done previously. In addition, the kinetics of the CO 2 chemical absorption process was evaluated by in situ Fourier transform infrared spectroscopy-attenuated total reflection, following the characteristic vibrational signals of the reactants and products over the reaction time. A chemical absorption model was used to describe the time-dependent concentration of species involved in the reactive absorption, obtaining kinetic parameters (such as chemical reaction kinetic constants and diffusion coefficients) as a function of temperatures and pressures. As expected, the results demonstrate that the CO 2 absorption rate is mass-transfer-controlled because of the relatively high viscosity of AHA-IL. The AHA-IL was encapsulated in a porous carbon sphere (Encapsulated Ionic Liquid, ENIL) to improve the kinetic performance of the AHA-IL for CO 2 capture. The newly synthesized AHA-ENIL material was evaluated as a CO 2 sorbent with gravimetric absorption measurements. AHA-ENIL systems preserve the good CO 2 absorption capacity of the AHA-IL but drastically enhance the CO 2 absorption rate because of the increased gas-liquid surface contact area achieved by solvent encapsulation.

Comparison of 2 micron Ho and 10 micron CO2 lidar for atmospheric backscatter and Doppler windshear detection

NASA Technical Reports Server (NTRS)

Killinger, Dennis

1991-01-01

The development of eye-safe, solid-state Lidar systems is discussed, with an emphasis on Coherent Doppler Lidar for Atmospheric Wind Measurements. The following subject areas are covered: tunable Ho DIAL (Differential Absorption Lidar)/lidar atmospheric measurements; atmospheric turbulence measurements and detector arrays; diurnal measurements of C(sub n)(sup 2) for KSC lidar measurements; and development of single-frequency Ho laser/lidar.

The High Accuracy Measurement of CO2 Mixing Ratio Profiles Using Ground Based 1.6 μm CO2-DIAL with Temperature Measurement Techniques in the Lower-Atmosphere

NASA Astrophysics Data System (ADS)

Abo, M.; Shibata, Y.; Nagasawa, C.

2017-12-01

We have developed a ground based direct detection three-wavelength 1.6 μm differential absorption lidar (DIAL) to achieve measurements of vertical CO2 concentration and temperature profiles in the atmosphere. As the spectra of absorption lines of any molecules are influenced basically by the temperature and pressure in the atmosphere, it is important to measure them simultaneously so that the better accuracy of the DIAL measurement is realized. Conventionally, we have obtained the vertical profile of absorption cross sections using the atmospheric temperature profile by the objective analysis and the atmospheric pressure profile calculated by the pressure height equation. Comparison of atmospheric pressure profiles calculated from this equation and those obtained from radiosonde observations at Tateno, Japan is consistent within 0.2 % below 3 km altitude. But the temperature dependency of the CO2 density is 0.25 %/°C near the surface. Moreover, the CO2 concentration is often evaluated by the mixing ratio. Because the air density is related by the ideal gas law, the mixing ratio is also related by the atmospheric temperature. Therefore, the temperature affects not only accuracy of CO2 concentration but the CO2 mixing ratio. In this paper, some experimental results of the simultaneous measurement of atmospheric temperature profiles and CO2 mixing ratio profiles are reported from 0.4 to 2.5 km altitude using the three-wavelength 1.6 μm DIAL system. Temperature profiles of CO2 DIAL measurement were sometimes different from those of objective analysis below 1.5 km altitude. These differences are considered to be due to regionality at the lidar site. The temperature difference of 5.0 °C corresponds to a CO2 mixing ratio difference of 8.0 ppm at 500 m altitude. This cannot be ignored in estimates of regional sources and sinks of CO2. This three-wavelength CO2 DIAL technique can estimate accurately temporal behavior of CO2 mixing ratio profiles in the lower atmosphere. This work was financially supported by the System Development Program for Advanced Measurement and Analysis of the Japan Science and Technology Agency.

CO2 concentration and temperature sensor for combustion gases using diode-laser absorption near 2.7 μm

NASA Astrophysics Data System (ADS)

Farooq, A.; Jeffries, J. B.; Hanson, R. K.

2008-03-01

A new tunable diode-laser sensor based on CO2 absorption near 2.7 μm is developed for high-resolution absorption measurements of CO2 concentration and temperature. The sensor probes the R(28) and P(70) transitions of the ν1+ν3 combination band of CO2 that has stronger absorption line-strengths than the bands near 1.5 μm and 2.0 μm used previously to sense CO2 in combustion gases. The increased absorption strength of transitions in this new wavelength range provides greatly enhanced sensitivity and the potential for accurate measurements in combustion gases with short optical path lengths. Simulated high-temperature spectra are surveyed to find candidate CO2 transitions isolated from water vapor interference. Measurements of line-strength, line position, and collisional broadening parameters are carried out for candidate CO2 transitions in a heated static cell as a function of temperature and compared to literature values. The accuracy of a fixed-wavelength CO2 absorption sensor is determined via measurement of known temperature and CO2 mole fraction in a static cell and shock-tube. Absorption measurements of CO2 are then made in a laboratory flat-flame burner and in ignition experiments of shock-heated n-heptane/O2/argon mixtures to illustrate the potential of this sensor for combustion and reacting-flow applications.

Integrated Path Differential Absorption Lidar Optimizations Based on Pre-Analyzed Atmospheric Data for ASCENDS Mission Applications

NASA Technical Reports Server (NTRS)

Pliutau, Denis; Prasad, Narasimha S.

2012-01-01

In this paper a modeling method based on data reductions is investigated which includes pre analyzed MERRA atmospheric fields for quantitative estimates of uncertainties introduced in the integrated path differential absorption methods for the sensing of various molecules including CO2. This approach represents the extension of our existing lidar modeling framework previously developed and allows effective on- and offline wavelength optimizations and weighting function analysis to minimize the interference effects such as those due to temperature sensitivity and water vapor absorption. The new simulation methodology is different from the previous implementation in that it allows analysis of atmospheric effects over annual spans and the entire Earth coverage which was achieved due to the data reduction methods employed. The effectiveness of the proposed simulation approach is demonstrated with application to the mixing ratio retrievals for the future ASCENDS mission. Independent analysis of multiple accuracy limiting factors including the temperature, water vapor interferences, and selected system parameters is further used to identify favorable spectral regions as well as wavelength combinations facilitating the reduction in total errors in the retrieved XCO2 values.

Estimation of the CO{sub 2} absorption capacities in aqueous 2-(2-aminoethylamino)ethanol and its blends with MDEA and TEA in the presence of SO{sub 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bonenfant, D.; Minleault, M.; Hausler, R.

2007-12-15

A study of carbon dioxide (CO{sub 2}) and sulfur dioxide (SO{sub 2})/CO{sub 2} mixtures absorption has been carried out in aqueous 2-(2-aminoethylamino)ethanol (AEE) solution and its blends with N-methyldiethanolamine (MDEA) and triethanolamine (TEA) to estimate the influence of SO{sub 2}, MDEA, and TEA on the CO{sub 2} absorption capacity of the AEE. The CO{sub 2} absorption loading has been estimated in 15 wt % AEE alone and in the presence of either 5 and 10 wt % MDEA or 5 and 10 wt % TEA solutions with 100 vol % CO{sub 2} and 5.03 and 15.02 vol % SO{sub 2}/CO{submore » 2} mixtures at a starting temperature of 296 K and flow rates of 3.067, 3.229, and 3.605 L/min, respectively. The results revealed that the presence of SO{sub 2} in the gas decreases the CO{sub 2} absorption rate and loading in the AEE solution as a function of the concentration of SO{sub 2}. The additions of 5 and 10 wt % of MDEA and TEA do not seem to influence the CO{sub 2} absorption rate in the AEE solution. Moreover, the addition of MDEA increases slightly the CO{sub 2} absorption capacity of AEE, while TEA decreases the absorption capacity of AEE in the absence and presence Of SO{sub 2}. These effects were enhanced with increases of MDEA and TEA. Altogether, the results indicated that the blend of 15 wt % AEE + 10 wt % MDEA represents an interesting solvent which could be used as absorbent for the removal of CO{sub 2} from emission into the atmosphere by industries.« less

Acyl CoA synthetase 5 (ACSL5) ablation in mice increases energy expenditure and insulin sensitivity and delays fat absorption

USDA-ARS?s Scientific Manuscript database

Objective: The family of acyl-CoA synthetase enzymes (ACSL) activates fatty acids within cells to generate long chain fatty acyl CoA (FACoA). The differing metabolic fates of FACoAs such as incorporation into neutral lipids, phospholipids, and oxidation pathways are differentially regulated by the ...

Absorption performance for CO2 capture process using MDEA-AMP aqueous solution

NASA Astrophysics Data System (ADS)

Liu, Gang; Kou, Liqing; Li, Chao

2017-03-01

The absorption capacity and the absorption rate of CO2 in 2-amino-2-methyl-1-propanol (AMP)-N-methyldiethanolamine (MDEA) aqueous solution were measured. The temperatures ranged from 303.2K to 323.2K. The mass fractions of AMP and MDEA respectively ranged from 0 to 0.03 and 0.2 to 0.3. The influence of temperature and w AMP on the absorption capacity and absorption rate of CO2 was illustrated.

Double-Pulse Two-Micron IPDA Lidar Simulation for Airborne Carbon Dioxide Measurements

NASA Technical Reports Server (NTRS)

Refaat, Tamer F.; Singh, Upendra N.; Yu, Jirong; Petros, Mulugeta

2015-01-01

An advanced double-pulsed 2-micron integrated path differential absorption lidar has been developed at NASA Langley Research Center for measuring atmospheric carbon dioxide. The instrument utilizes a state-of-the-art 2-micron laser transmitter with tunable on-line wavelength and advanced receiver. Instrument modeling and airborne simulations are presented in this paper. Focusing on random errors, results demonstrate instrument capabilities of performing precise carbon dioxide differential optical depth measurement with less than 3% random error for single-shot operation from up to 11 km altitude. This study is useful for defining CO2 measurement weighting, instrument setting, validation and sensitivity trade-offs.

NO and NO2 emission ratios measured from in-use commercial aircraft during taxi and takeoff.

PubMed

Herndon, Scott C; Shorter, Joanne H; Zahniser, Mark S; Nelson, David D; Jayne, John; Brown, Robert C; Miake-Lye, Richard C; Waitz, Ian; Silva, Phillip; Lanni, Thomas; Demerjian, Ken; Kolb, Charles E

2004-11-15

In August 2001, the Aerodyne Mobile Laboratory simultaneously measured NO, NO2, and CO2 within 350 m of a taxiway and 550 m of a runway at John F. Kennedy Airport. The meteorological conditions were such that taxi and takeoff plumes from individual aircraft were clearly resolved against background levels. NO and NO2 concentrations were measured with 1 s time resolution using a dual tunable infrared laser differential absorption spectroscopy instrument, utilizing an astigmatic multipass Herriott cell. The CO2 measurements were also obtained at 1 s time resolution using a commercial non-dispersive infrared absorption instrument. Plumes were measured from over 30 individual planes, ranging from turbo props to jumbo jets. NOx emission indices were determined by examining the correlation between NOx (NO + NO2) and CO2 during the plume measurements. Several aircraft tail numbers were unambiguously identified, allowing those specific airframe/engine combinations to be determined. The resulting NOx emission indices from positively identified in-service operating airplanes are compared with the published International Civil Aviation Organization engine certification test database collected on new engines in certification test cells.

Differential photo-acoustic gas cell based on LTCC for ppm gas sensing

NASA Astrophysics Data System (ADS)

Keränen, K.; Kautio, K.; Ollila, J.; Heikkinen, M.; Kauppinen, I.; Kuusela, T.; Matveev, B.; McNie, M. E.; Jenkins, R. M.; Karioja, P.

2010-02-01

Silicon MEMS cantilever-based photoacoustic technology allows for the sensing of ultra low gas concentrations with very wide dynamic range. The sensitivity enhancement is achieved with a cantilever microphone system in which the cantilever displacement is probed with an optical interferometer providing a pico-meter resolution. In the gas sensor, the silicon cantilever microphone is placed in a two-chamber differential gas cell. By monitoring differential pressure changes between the two chambers, the differential cell operates as a differential infra-red detector for optical absorption signals through a measurement and reference path. The differential pressure signal is proportional to gas concentration in the optical measurement path. We have designed, implemented and tested a differential photo-acoustic gas cell based on Low Temperature Co-fired Ceramic (LTCC) multilayer substrate technology. Standard LTCC technology enables implementation of 2.5D structures including holes, cavities and channels into the electronic substrate. The implemented differential photoacoustic gas cell structure includes two 10 mm long cylindrical cells, diameter of 2.4 mm. Reflectance measurements of the cell showed that reflectivity of the substrate material can be improved by a factor 15 - 90 in the 3 - 8 μm spectral region using gold or silver paste coatings. A transparent window is required in the differential gas cell structure in order to probe the displacement of the silicon cantilever. The transparent sapphire window was sealed to the LTCC substrate using two methods: screen printed Au80/Sn20 solder paste and pre-attached glass solder paste (Diemat DM2700P/H848). Both methods were shown to provide hermetic sealing of sapphire windows to LTCC substrate. The measured He-leak rate for the 10 sealed test samples implemented using glass paste were under 2.0 ×10-9 atm×cm3/s, which meets the requirement for the leak rate according to MIL-STD 883. The achieved hermeticity level suggests that the proof-of-principle packaging demonstrator paves the way for implementing a novel differential photoacoustic gas cell for a future miniature gas sensor module. The future module consisting of a sample gas cell and immersion lens IR LEDs together with interferometric probing of the cantilever microphone is expected to be capable of measuring ultra low concentrations of a wide range of gases with their fundamental absorption bands at 3 - 7 μm wavelength, such as CO, CO2 and CH4.

Growth of nano hexagon-like flake arrays cerium carbonate created with PAH as the substrate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, M., E-mail: limei@imust.cn; School of Materials and Metallurgy, Inner Mongolia University of Science and Technology, Department of Inorganic and Metalloid Materials, Key Laboratory of New Technologies of Modern Metallurgy and Application of Rare Materials, Baotou 014010; Hu, Y.H., E-mail: bthyh@163.com

Petals-like Ce{sub 2}(CO{sub 3}){sub 3} on Ce{sub 2}(CO{sub 3}){sub 3} nano hexagon-like flake arrays have been precipitatingly fabricated using PAH substrates. By changing the way of feeding, PAH concentration and aging time, petals-like Ce{sub 2}(CO{sub 3}){sub 3} was created best when adding PAH into the Ce(NO{sub 3}){sub 3} solution, joined (NH{sub 4}){sub 2}CO{sub 3} solution along with mixing, PAH concentration is 0.9 g/L, aging time is 4 h. A growth mechanism was proposed to account for the growth of the petals-like Ce{sub 2}(CO{sub 3}){sub 3} with PAH as the substrate. Poly allylamine hydrochloride (PAH) is as template agent which formsmore » π-allyl complex with Ce{sup 3+} and controls the morphology of Ce{sub 2}(CO{sub 3}){sub 3} particle. PAH and Ce{sup 3+} form π-allyl complex, and then induce the formation of Ce{sub 2}(CO{sub 3}){sub 3} crystal nucleus. And infrared spectrum analysis verified. XRD show that after adding PAH which is adsorbed on the crystal plane, the growth of Ce{sub 2}(CO{sub 3}){sub 3} crystal is inhibited on (2 4 2), the growth is promoted on (2 0 2) which is differentiated into the new (1 5 1), (2 2 2) is unchanged, Ce{sub 2}(CO{sub 3}){sub 3} crystal is accumulated petals shape by hexagon-like flake. UV absorption spectra show that CeO{sub 2} as prepared precursor Ce{sub 2}(CO{sub 3}){sub 3} after calcinations in air at high temperatures, the petal-like CeO{sub 2} has strong UV absorption and reflection effects, and absorption interval changed significantly by the move to UVA from UVB. - Graphical abstract: Each Ce-atom connects three Cl-atoms and three allyls in three dimensional spaces. To take the plane as a reference plane which is arrayed with three Ce-atom as equilateral triangle. The triangular each vertex is Ce-atom, the triangular center place is Cl-atom, the equilateral triangle which is mutually perpendicular with Ce-triangle surface and the inclined angle is 60° is made up with three Cl-atoms. - Highlights: • Petals-like Ce{sub 2}(CO{sub 3}){sub 3} were synthesized with PAH. • PAH and Ce{sup 3+} form π-allyl complex. • The growth crystal is inhibited on (2 4 2) and promoted on (2 0 2). • CeO{sub 2} absorption interval changed by the move to UVA from UVB.« less

Atmospheric remote sensing of water vapor, HCl and CH4 using a continuously tunable Co:MgF2 laser

NASA Technical Reports Server (NTRS)

Menyuk, Norman; Killinger, Dennis K.

1987-01-01

A differential-absorption lidar system has been developed which uses a continuously tunable (1.5-2.3 micron) cobalt-doped magnesium fluoride laser as the radiation source. Preliminary atmospheric measurements of water vapor, HCl, and CH4 have been made with this system, including both path-averaged and ranged-resolved DIAL measurements at ranges up to 6 and 3 km, respectively.

Atmospheric CO2 measurements with a 2-μm DIAL instrument

NASA Astrophysics Data System (ADS)

Cadiou, Erwan; Dherbecourt*, Jean-Baptiste; Gorju, Guillaume; Melkonian, Jean-Michel; Godard, Antoine; Pelon, Jacques; Raybaut, Myriam

2018-04-01

We report on ground-based atmospheric concentration measurements of carbon dioxide, using a pulsed direct detection differential absorption lidar operating at 2051 nm. The transmitter is based on a tunable parametric source emitting 10-mJ energy, 10-ns duration Fourier-limited pulses. Range resolved concentration measurements have been carried out on the aerosol back-scattered signal. Cloud signals have been used to get long range integrated-path measurements.

Mesoporous fluorocarbon-modified silica aerogel membranes enabling long-term continuous CO2 capture with large absorption flux enhancements.

PubMed

Lin, Yi-Feng; Chen, Chien-Hua; Tung, Kuo-Lun; Wei, Te-Yu; Lu, Shih-Yuan; Chang, Kai-Shiun

2013-03-01

The use of a membrane contactor combined with a hydrophobic porous membrane and an amine absorbent has attracted considerable attention for the capture of CO2 because of its extensive use, low operational costs, and low energy consumption. The hydrophobic porous membrane interface prevents the passage of the amine absorbent but allows the penetration of CO2 molecules that are captured by the amine absorbent. Herein, highly porous SiO2 aerogels modified with hydrophobic fluorocarbon functional groups (CF3 ) were successfully coated onto a macroporous Al2 O3 membrane; their performance in a membrane contactor for CO2 absorption is discussed. The SiO2 aerogel membrane modified with CF3 functional groups exhibits the highest CO2 absorption flux and can be continuously operated for CO2 absorption for extended periods of time. This study suggests that a SiO2 aerogel membrane modified with CF3 functional groups could potentially be used in a membrane contactor for CO2 absorption. Also, the resulting hydrophobic SiO2 aerogel membrane contactor is a promising technology for large-scale CO2 absorption during the post-combustion process in power plants. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

CO2 capture by ionic liquids - an answer to anthropogenic CO2 emissions?

PubMed

Sanglard, Pauline; Vorlet, Olivier; Marti, Roger; Naef, Olivier; Vanoli, Ennio

2013-01-01

Ionic liquids (ILs) are efficient solvents for the selective removal of CO2 from flue gas. Conventional, offthe-shelf ILs are limited in use to physisorption, which restricts their absorption capacity. After adding a chemical functionality like amines or alcohols, absorption of CO2 occurs mainly by chemisorption. This greatly enhances CO2 absorption and makes ILs suitable for potential industrial applications. By carefully choosing the anion and the cation of the IL, equimolar absorption of CO2 is possible. This paper reviews the current state of the art of CO2 capture by ILs and presents the current research in this field performed at the ChemTech Institute of the Ecole d'Ingénieurs et d'Architectes de Fribourg.

Evaluation of a HgCdTe e-APD based detector for 2  μm CO2 DIAL application.

PubMed

Dumas, Arnaud; Rothman, Johan; Gibert, Fabien; Édouart, Dimitri; Lasfargues, Gilles; Cénac, Claire; Mounier, Florian Le; Pellegrino, Jessica; Zanatta, Jean-Paul; Bardoux, Alain; Tinto, Francesc; Flamant, Pierre

2017-09-20

Benefiting from close to ideal amplification properties (high gain, low dark current, and low excess noise factor), HgCdTe electron initiated avalanche photodiode (e-APD) technology exhibits state of the art sensitivity, thus being especially relevant for applications relying on low light level detection, such as LIDAR (Light Detection And Ranging). In addition, the tunable gap of the Hg 1-x Cd x Te alloy enables coverage of the short wavelength infrared (SWIR) and especially the 2 μm spectral range. For these two reasons, a HgCdTe e-APD based detector is a promising candidate for future differential absorption LIDAR missions targeting greenhouse gas absorption bands in SWIR. In this study, we report on the design and evaluation of such a HgCdTe e-APD based detector. The first part focuses on detector architecture and performance. Key figures of merit are: 2.8 μm cutoff wavelength, 200 μm diameter almost circular sensitive area, 185 K operating temperature (thermo-electric cooling), 22 APD gain (at 12 V reverse bias), 360  kΩ transimpedance gain, and 60  fWHz -0.5 noise equivalent power (at 12 V reverse bias). The second part presents an analysis of atmospheric LIDAR signals obtained by mounting the HgCdTe e-APD based detector on the 2 μm differential absorption LIDAR developed at the Laboratoire de Météorologie Dynamique and dedicated to CO 2 monitoring. Discussion emphasizes random and systematic errors in LIDAR measurements regarding breadboard detector characterization. In particular, we investigate the influence of parasitic tails in detector impulse response on short range DIAL measurements.

Synthesis and characterization of metastable, 20 nm-sized Pna2{sub 1}-LiCoPO{sub 4} nanospheres

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ludwig, Jennifer; Nordlund, Dennis; Doeff, Marca M.

The majority of research activities on LiCoPO{sub 4} are focused on the phospho-olivine (space group Pnma), which is a promising high-voltage cathode material for Li-ion batteries. In contrast, comparably little is known about its metastable Pna2{sub 1} modification. Herein, we present a comprehensive study on the structure–property relationships of 15–20 nm Pna2{sub 1}-LiCoPO{sub 4} nanospheres prepared by a simple microwave-assisted solvothermal process. Unlike previous reports, the results indicate that the compound is non-stoichiometric and shows cation-mixing with Co ions on the Li sites, which provides an explanation for the poor electrochemical performance. Co L{sub 2,3}-edge X-ray absorption spectroscopic data confirmmore » the local tetrahedral symmetry of Co{sup 2+}. Comprehensive studies on the thermal stability using thermogravimetric analysis, differential scanning calorimetry, and in situ powder X-ray diffraction show an exothermic phase transition to olivine Pnma-LiCoPO{sub 4} at 527 °C. The influence of the atmosphere and the particle size on the thermal stability is also investigated. - Graphical abstract: Blue nano-sized Pna2{sub 1}-LiCoPO{sub 4,} featuring tetrahedrally-coordinated Co{sup 2+}, was synthesized in a rapid one-step microwave-assisted solvothermal process. The phase relation between this metastable and the stable polymorph was analyzed and electrochemical properties are discussed. - Highlights: • Preparation of uniform 15–20 nm nanospheres of metastable Pna2{sub 1}-LiCoPO{sub 4} polymorph. • Structure redetermination shows cation-mixing (Co blocking Li sites). • In situ investigation of phase transformation to olivine Pnma-LiCoPO{sub 4} at 527 °C. • Pna2{sub 1}-LiCoPO{sub 4} reemerges as a stable high-temperature phase above 800 °C. • X-ray absorption spectroscopy confirms local tetrahedral symmetry (T{sub d} Co{sup 2+}).« less

Development of the 1.6μm OPG/OPA system wavelength-controlled precisely for CO2 DIAL

NASA Astrophysics Data System (ADS)

Abo, M.; Shibata, Y.; Nagasawa, C.

2010-12-01

We developed an optical parametric oscillator (OPO) laser system for 1.6μm CO2 DIAL1). In order to improve the measurement accuracy of CO2 profiles, development of high power and wavelength stabilized laser system has been conducted. We report a new high-power 1.6μm laser transmitter based on a parametric master oscillator-power amplifier (MOPA) system pumped by a LD-pumped Q-switched Nd:YAG laser which has the injection seed laser locked to the iodine absorption line. The master oscillator is an optical parametric generator (OPG), based on an MgO-doped periodically poled LiTaO3 (PPMgLT) crystal. The OPOs require either active control of the cavity length or slight misalignment of the cavity. On the other hand, the OPGs do not require a cavity and instead rely on sufficient conversion efficiency to be obtained with a single pass through the crystal. The single-frequency oscillation of the OPG was achieved by injection seeding. The 1.6μm emission of the OPG is amplified by two-stage optical parametric amplifiers (OPAs). The each PPMgLT crystal was mounted on the copper holder, and the temperature control of the each holder was carried out within 0.01 K. The wavelength feedback system of the Nd:YAG seed laser is performed with the side locking of the iodine absorption spectrum (line No.1107) and the frequency stability is realized within 10 MHz rms. Stabilization of the 1.6μm DFB seed laser is estimated to within 4 MHz rms at the CO2 absorption line center and within 1.8 MHz rms at the CO2 absorption line slope using the wavelength control unit. We demonstrated single-longitudinal-mode emission with the OPG and two OPAs. The beam quality was TEM00 mode, the pulse energy was 12 mJ at 500 Hz repetition rate and the frequency stability was less than 10MHz rms. The unique performances of this optical parametric system make a relevant transmitter for CO2 DIAL. This work was financially supported by the System Development Program for Advanced Measurement and Analysis of the Japan Science and Technology Agency. Reference (1) D. Sakaisawa, C. Nagasawa, T. Nagai, M. Abo, Y. Shibata, H. Nagai, M. Nakazato, and T. Sakai, Development of a 1.6μm differential absorption lidar with a quasi-phase-matching optical parametric oscillator and photon-counting detector for the vertical CO2 profile, Applied Optics, Vol.48, No.4, pp.748-757, 2009.

CO2 Absorption from Biogas by Glycerol: Conducted in Semi-Batch Bubble Column

NASA Astrophysics Data System (ADS)

puji lestari, Pratiwi; Mindaryani, Aswati; Wirawan, S. K.

2018-03-01

Biogas is a renewable energy source that has been developed recently. The main contents of Biogas itself are Methane and carbon dioxide (CO2) where Methane is the main component of biogas with CO2 as the highest impurities. The quality of biogas depends on the CO2 content, the lower CO2 levels, the higher biogas quality. Absorption is one of the methods to reduce CO2 level. The selections of absorbent and appropriate operating parameters are important factors in the CO2 absorption from biogas. This study aimed to find out the design parameters for CO2 absorption using glycerol that represented by the overall mass transfer coefficient (KLa) and Henry’s constant (H). This study was conducted in semi-batch bubble column. Mixed gas was contacted with glycerol in a bubble column. The concentration of CO2 in the feed gas inlet and outlet columns were analysed by Gas Chromatograph. The variables observed in this study were superficial gas velocity and temperatures. The results showed that higher superficial gas velocity and lower temperature increased the rate of absorption process and the amount of CO2 absorbed.

Development of tunable high pressure CO2 laser for lidar measurements of pollutants and wind velocities, January 1976 to December 1977

NASA Technical Reports Server (NTRS)

Javan, A.

1979-01-01

A tunable multiatmospheric pulsed CO2 laser with emphasis on experimental features and supporting theoretical analyses important to differential absorption lidar and Doppler lidar measurement of pollutants and wind velocities is reported. The energy deposition and the means to produce the uniform high density plasma in the multiatmospheric medium, through UV preionization of an organic seed gas is discussed. Design features of the pulsed CO2 laser are presented. The radiative processes which are operative and prevent the laser from breaking into oscillations in a large number of modes over its broad amplification bandwidth are described. The mode competition for the transient pulsed laser oscillation in a standing wave and traveling wave ring laser configuration is discussed and contrasted with the approach to steady state oscillations. The latter findings are important to transient injection locking for production of a highly stable pulsed CO2 laser output.

Diffusion coefficients significant in modeling the absorption rate of carbon dioxide into aqueous blends of N-methyldiethanolamine and diethanolamine and of hydrogen sulfide into aqueous N-methyldiethanolamine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adams, M.E.; Marshall, T.L.; Rowley, R.L.

1998-07-01

Absorption rates of gaseous CO{sub 2} into aqueous blends of N-methyldiethanolamine (MDEA) and diethanolamine (DEA) and of gaseous H{sub 2}S into aqueous MDEA were measured in a quiescent, inverted-tube diffusiometer by monitoring the rate of pressure drop. A numerical model for absorption, diffusion, and reaction of CO{sub 2} and H{sub 2}S in blends of MDEA, DEA, and water was developed. The model was used to regress diffusion coefficients of bicarbonate, carbamate, and MDEAH{sub 2}CO{sub 3} for the case of CO{sub 2} absorption and of bisulfide ion for the case of H{sub 2}S absorption from measured absorption rates. CO{sub 2} absorptionmore » rates and diffusion coefficients of bicarbonate, carbamate, and MDEAH{sub 2}CO{sub 3} were obtained at 298.2 K and 318.2 K in aqueous solutions containing 50 mass % total amine at DEA:MDEA mole ratios of 1:20, 1:4, 1L3, and 2:3. H{sub 2}S absorption rates and diffusion coefficients of bisulfide ion were obtained at 298.2 K and 318.2 K in aqueous solutions containing 20, 35, and 50 mass % MDEA.« less

Absorption of Carbon Dioxide in Aqueous Solutions of N-methyldiethanolamine Mixtures

NASA Astrophysics Data System (ADS)

Ma’mun, S.; Svendsen, H. F.

2018-05-01

Carbon dioxide (CO2) is one of the greenhouse gases (GHG) that has contributed to the global warming problem. Carbon dioxide is produced in large quantity from coal-fired power plants, iron and steel production, cement production, chemical and petrochemical industries, natural gas purification, and transportation. Some efforts to reduce the CO2 emissions to the atmosphere are then required. Amine-based absorption may be an option for post-combustion capture. The objective of this study is to measure the effect of promoter addition as well as MDEA concentration for the CO2 absorption into the aqueous solutions of MDEA to improve its performances, i.e. increasing the absorption rate and the absorption capacity. Absorption of CO2 in aqueous solutions of MDEA mixtures were measured at 40 °C in a bubble tank reactor. The systems tested were the mixtures of 30 wt% MDEA with 5 and 10 wt% BEA and the mixtures of 40 and 50 wt% MDEA with 6 wt% AEEA. It was found that for MDEA-BEA-H2O mixtures, the higher the promoter concentraation the higher the CO2 absorption rate, while for the MDEA-AEEA-H2O mixtures, the higher the MDEA concentration the lower the CO2 absorption rate.

Development of a laser remote sensing instrument to measure sub-aerial volcanic CO2 fluxes

NASA Astrophysics Data System (ADS)

Queisser, Manuel; Burton, Mike

2016-04-01

A thorough quantification of volcanic CO2 fluxes would lead to an enhanced understanding of the role of volcanoes in the geological carbon cycle. This would enable a more subtle understanding of human impact on that cycle. Furthermore, variations in volcanic CO2 emissions are a key to understanding volcanic processes such as eruption phenomenology. However, measuring fluxes of volcanic CO2 is challenging as volcanic CO2 concentrations are modest compared with the ambient CO2 concentration (~400 ppm) . Volcanic CO2 quickly dilutes with the background air. For Mt. Etna (Italy), for instance, 1000 m downwind from the crater, dispersion modelling yields a signal of ~4 ppm only. It is for this reason that many magmatic CO2 concentration measurements focus on in situ techniques, such as direct sampling Giggenbach bottles, chemical sensors, IR absorption spectrometers or mass spectrometers. However, emission rates are highly variable in time and space. Point measurements fail to account for this variability. Inferring 1-D or 2-D gas concentration profiles, necessary to estimate gas fluxes, from point measurements may thus lead to erroneous flux estimations. Moreover, in situ probing is time consuming and, since many volcanoes emit toxic gases and are dangerous as mountains, may raise safety concerns. In addition, degassing is often diffuse and spatially extended, which makes a measurement approach with spatial coverage desirable. There are techniques that allow to indirectly retrieve CO2 fluxes from correlated SO2 concentrations and fluxes. However, they still rely on point measurements of CO2 and are prone to errors of SO2 fluxes due to light dilution and depend on blue sky conditions. Here, we present a new remote sensing instrument, developed with the ERC project CO2Volc, which measures 1-D column amounts of CO2 in the atmosphere with sufficient sensitivity to reveal the contribution of magmatic CO2. Based on differential absorption LIDAR (DIAL) the instrument measures the absorption, and therefore path amount, of CO2 in the atmosphere. The kit has been optimized to be rugged, man-portable and to use little power (~ 70W). By flying the instrument over a volcanic plume we will be able to swiftly determine CO2 fluxes. This opens the possibility of rapid, comprehensive surveys of both point source, open-vent CO2 emissions, as well as emissions from more diffuse sources such as lakes and fumarole fields. We present initial test results from the new instrument. We believe that the CO2 LIDAR could make a major contribution to volcano monitoring. Potential follow-on applications include environmental monitoring, such as fugitive CO2 detection in storage sites or urban monitoring of car and ship emissions.

Line by Line CO2 Absorption in the Atmosphere for Input Data to Calculate Global Warming, David C. Smith, DCS Lasers & Optics LLC, Old Saybrook CT 06475

NASA Astrophysics Data System (ADS)

Smith, D. C.

2012-12-01

Compter modeling of global climate change require an input (asssumption) of the forcing function for CO2 absorption. All codes use a long term forcing function of ~ 4 W/M2. (IPCC 2007 Summary for Policymakers. In:Climate Change 2007. The Physical Sciences Basis.Contributions of Working Group 1 to the Fourth Assessment Report of the IPCC, Cambridge U. Press N.Y.)..This is based on a band model of the CO2 rotational/vibrational absorption where a band of absorption averages over all the rotational levels of the vibration transition. (Ramananathan,V.,et al, J. of Geophysical Research,Vol 84 C8,p4949,Aug.1979).. The model takes into account the line width,the spacing between lines and identifies 10 CO2 bands.. This approach neglects the possibility that the peak absorption transitions in a band can "use up" all of the earths IR radiation at that wavelength and does not contribute to global warming no matter how much the CO2 is increased. The lines in the wings of a band increase their absorption as the CO2 is increased. However, the lines that are lost are the strong absorbers and those that are added are the weaker absorption lines. When a band begins to use up the IR then the net result of increasing the atmospheric CO2 is a decrease in the absorption change. This presentation calculates the absorption of each line individualy using the Behr's Law Approach. The dependence of the absorption and line width of each transition as a function of altitude is accounted for. The temperature dependence of the absorption with altitude is not and an evaluation of this error is given. For doubling CO2 from 320ppm to 640 ppm, the calculation gives a forcing function of 1.1 W/M2. The results show the importance of using individual lines to calculate the CO2 contribution to global warming, We can speculate on the imact and anticipate a computer code calculation of a factor of 4 less global warming than the published results.

Ultraviolet absorption spectra of shock-heated carbon dioxide and water between 900 and 3050 K

NASA Astrophysics Data System (ADS)

Schulz, C.; Koch, J. D.; Davidson, D. F.; Jeffries, J. B.; Hanson, R. K.

2002-03-01

Spectrally resolved UV absorption cross-sections between 190 and 320 nm were measured in shock-heated CO 2 between 880 and 3050 K and H 2O between 1230 and 2860 K. Absorption spectra were acquired with 10 μs time resolution using a unique kinetic spectrograph, thereby enabling comparisons with time-dependent chemical kinetic modeling of post-shock thermal decomposition and chemical reactions. Although room temperature CO 2 is transparent (σ<10 -22 cm2) at wavelengths longer than 200 nm, hot CO 2 has significant absorption (σ>10 -20 cm2) extending to wavelengths longer than 300 nm. The temperature dependence of CO 2 absorption strongly suggests sharply increased transition probabilities from excited vibrational levels.

Kinetics study of carbon dioxide absorption reaction into the promoted methyldiethanolamine solution

NASA Astrophysics Data System (ADS)

Sitorus, Yasmikha Tiurlan Susanti; Taurina, Hanna Sucita; Altway, Ali; Rahmawati, Yeni; Nurkhamidah, Siti

2017-05-01

The absorption of carbon dioxide (CO2) is important in the industrial world. In industries, especially petrochemical, oil, and natural gas sectors, separation process of CO2 gas which is a corrosive gas (acid gas) is required. So, the separation process of CO2 gas stream is important, one of the methods used to remove CO2 from the gas stream is reactive absorption process using the promoted methyldiethanolamine (MDEA) solution. Therefore, this study is aimed to obtain the reaction kinetics data of CO2 absorption in MDEA solution using arginine as a promoter. Arginine was chosen because of its amino acid molecule which is reactive, so it can accelerate the reaction rate of MDEA. Moreover, this study also made a comparison between the reactivity of MDEA solution using arginine and MDEA solution using other promoters (glycine and piperazine) for CO2 absorption. The method used is absorption using laboratory scale of Wetted Wall Column (WWC) equipment at 1 atm. This study provides the reaction kinetics data information in order to optimize the separation process of CO2 in the industrialized world. The experimental results show that CO2 absorption rate at 323.15 K without any additon of arginine is 2.33 × 10-7 kmol/sec. By addition of 0.5 and 1 wt% of arginine, the absorption rate becomes 4 × 10-7 kmol/sec (2 times larger) and 6 × 10-7 kmol/sec (3 times larger). These results show that the addition of arginine as a promoter can increase the absorption rate of CO2 in MDEA solution and cover the weaknesses of MDEA solution. Based on the experimental result, the reaction kinetics constant for arginine is 1.91 × 1025 exp (-12296/T) (m3/kmol.s). Although, arginine reaction rate constant is lower than glycine and piperazine.

CARBON DIOXIDE SEPARATION BY PHASE ENHANCED GAS-LIQUID ABSORPTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liang Hu

A new process called phase enhanced gas-liquid absorption has been developed in its early stage. It was found that adding another phase into the absorption system of gas/aqueous phase could enhance the absorption rate. A system with three phases was studied. In the system, gas phase was carbon dioxide. Two liquid phases were used. One was organic phase. Another was aqueous phase. By addition of organic phase into the absorption system of CO{sub 2}-aqueous phase, the absorption rate of CO{sub 2} was increased significantly. CO{sub 2} finally accumulated into aqueous phase. The experimental results proved that (1) Absorption rate ofmore » carbon dioxide was enhanced by adding organic phase into gas aqueous phase system; (2) Organic phase played the role of transportation of gas solute (CO{sub 2}). Carbon dioxide finally accumulated into aqueous phase.« less

Measurements of CO2 Column Abundance in the Low Atmosphere Using Ground Based 1.6 μm CO2 DIAL

NASA Astrophysics Data System (ADS)

Abo, M.; Shibata, Y.; Nagasawa, C.

2017-12-01

Changes in atmospheric carbon dioxide (CO2) concentration are believed to produce the largest radiative forcing for the current climate system. Accurate predictions of atmospheric CO2 concentration rely on the knowledge of its sinks and sources, transports, and its variability with time. Although this knowledge is currently unsatisfactory, numerical models use it as a way in simulating CO2 fluxes. Validating and improving the global atmospheric transport model, therefore, requires precise measurement of the CO2 concentration profile. There are two further variations on Lidar: the differential absorption Lidar (DIAL) and the integrated path differential absorption (IPDA) Lidar. DIAL/IPDA are basically for profile/total column measurement, respectively. IPDA is a special case of DIAL and can measure the total column-averaged mixing ratio of trace gases using return signals from the Earth's surface or from thick clouds based on an airborne or a satellite. We have developed a ground based 1.6 μm DIAL to measure vertical CO2 mixing ratio profiles from 0.4 to 2.5 km altitude. The goals of the CO2 DIAL are to produce atmospheric CO2 mixing ratio measurements with much smaller seasonal and diurnal biases from the ground surface. But, in the ground based lidar, return signals from around ground surface are usually suppressed in order to handle the large dynamic range. To receive the return signals as near as possible from ground surface, namely, the field of view (FOV) of the telescope must be wide enough to reduce the blind range of the lidar. While the return signals from the far distance are very weak, to enhance the sensitivity and heighten the detecting distance, the FOV must be narrow enough to suppress the sky background light, especially during the daytime measurements. To solve this problem, we propose a total column measurement method from the ground surface to 0.4 km altitude. Instead of strong signals from thick clouds such as the IPDA, the proposed method uses atmospheric return signals from 0.4 km altitude. Although laser outputs of two wavelengths, which are the system parameter of DIAL, are canceled, the proposed method needs to constantly monitor laser outputs. When the laser output ratio with two wavelengths is 1.0 ± 0.01, the error simulation result of the CO2 mixing ratio is 420.0 ± 3.9 ppm.

Feasibility Study of Space-based CO2 Remote Sensing Using Pulsed 2-micron Integrated Path Differential Absorption Lidar

NASA Astrophysics Data System (ADS)

Singh, U. N.; Refaat, T. F.; Ismail, S.; Davis, K. J.; Kawa, S. R.; Menzies, R. T.; Petros, M.; Yu, J.

2016-12-01

Carbon dioxide (CO2) is recognized as the most important anthropogenic greenhouse gas. While CO2 concentration is rapidly increasing, understanding of the global carbon cycle remains a primary scientific challenge. This is mainly due to the lack of full characterization of CO2 sources and sinks. Quantifying the current global distribution of CO2 sources and sinks with sufficient accuracy and spatial resolution is a critical requirement for improving models of carbon-climate interactions and for attributing them to specific biogeochemical processes. This requires sustained atmospheric CO2 observations with high precision, and low bias for high accuracy, and spatial and temporal dense representation that cannot be fully realized with current CO2 observing systems, including existing satellite CO2 passive remote sensors. Progress in 2-micron instrument technologies, airborne testing, and system performance simulations indicates that the necessary lower tropospheric weighted CO2 measurements can be achieved from space using new high pulse energy 2-micron direct detection active remote sensing. Advantages of the CO2 active remote sensing include low bias measurements that are independent of sun light or Earth's radiation and day/night coverage over all latitudes and seasons. In addition, the direct detection system provides precise ranging with simultaneous measurement of aerosol and cloud distributions. The 2-micron active remote sensing offers strong CO2 absorption lines with optimum low tropospheric and near surface weighting. A feasibility study, including system optimization and sensitivity analysis of a space-based 2-micron pulsed IPDA lidar for CO2 measurement, is presented. This is based on the successful demonstration of the CO2 double-pulse IPDA lidar and the technology maturation of the triple-pulse IPDA lidar, currently under development at NASA Langley Research Center. Preliminary simulations indicate CO2 random measurement errors of 0.71, 0.35 and 0.13 ppm for snow, ocean surface, and desert surface reflectivity, respectively. These simulations assume a 400 km altitude polar orbit, 100 mJ pulse energy, a 1.5 m telescope, a 6.2 MHz detection bandwidth, 0.05 aerosol optical depth and 7 second data average.

A simulation study on the abatement of CO2 emissions by de-absorption with monoethanolamine.

PubMed

Greer, T; Bedelbayev, A; Igreja, J M; Gomes, J F; Lie, B

2010-01-01

Because of the adverse effect of CO2 from fossil fuel combustion on the earth's ecosystems, the most cost-effective method for CO2 capture is an important area of research. The predominant process for CO2 capture currently employed by industry is chemical absorption in amine solutions. A dynamic model for the de-absorption process was developed with monoethanolamine (MEA) solution. Henry's law was used for modelling the vapour phase equilibrium of the CO2, and fugacity ratios calculated by the Peng-Robinson equation of state (EOS) were used for H2O, MEA, N2 and O2. Chemical reactions between CO2 and MEA were included in the model along with the enhancement factor for chemical absorption. Liquid and vapour energy balances were developed to calculate the liquid and vapour temperature, respectively.

Absorption of CO2 from modified flue gases of power generation Tarahan chemically using NaOH and Na2CO3 and biologically using microalgae

NASA Astrophysics Data System (ADS)

Purba, Elida; Agustina, Dewi; Putri Pertama, Finka; Senja, Fita

2018-03-01

This research was carried out on the absorption of CO2 from the modified flue gases of power generation Tarahan using NaOH (sodium hydroxide) and Na2CO3 (sodium carbonate). The operation was conducted in a packed column absorber and then the output gases from the packed column was fed into photo-bioreactor for biological absorption. In the photo-bioreactor, two species of microalgae, N. occulata and T. chuii, were cultivated to both absorb CO2 gas and to produce biomass for algal oil. The aims of this research were, first, to determine the effect of absorbent flow rate on the reduction of CO2 and on the decrease of output gas temperature, second, to determine the characteristics of methyl ester obtained from biological absorption process. Flow rates of the absorbent were varied as 1, 2, and 3 l/min. The concentrations of NaOH and Na2CO3 were 1 M at a constant gas flow rate of 6 l/min. The output concentrations of CO2 from the absorber was analyzed using Gas Chromatography 2014-AT SHIMADZU Corp 08128. The results show that both of the absorbents give different trends. From the absorption using NaOH, it can be concluded that the higher the flow rate, the higher the absorption rate obtained. The highest flow rate achieved maximum absorption of 100%. On the other hand, absorption with Na2CO3 revealed the opposite trend where the higher the flow rates the lower the absorption rate. The highest absorption using Na2CO3 was obtained with the lowest flow rate, 1 l/min, that was 45,5%. As the effect of flow rate on output gas temperature, the temperature decreased with increasing flow rates for both absorbents. The output gas temperature for NaOH and Na2CO3 were consecutively 35 °C and 31 °C with inlet gas temperature of 50°C. Absorption of CO2 biologically resulted a reduction of CO2 up to 60% from the input gas concentration. Algal oil was extracted with mixed hexane and chloroform to obtain algal oil. Extracted oil was transesterified to methyl ester using sodium hydroxide as a catalyst. The results of in-situ transesterification method cannot be identified. Both microalgae achieved maximum yield at 2% catalyst concentration. Nannochloropsis occulata achieved the highest yield of algal oil that is 88.5%. The highest content of methyl ester from Nannochloropsis occulata was undecanoic acid methyl ester by 55.42% and the result from Tetraselmis chuii was palmitic acid methyl ester by 81.58%.

Simultaneous absorption of CO2 and H2S into aqueous blends of N-methyldiethanolamine and diethanolamine.

PubMed

Mandald, Bishnupada; Bandyopadhyay, Shyamalendu S

2006-10-01

Removal of CO2 from gaseous streams by absorption with chemical reaction in the liquid phase is usually employed in industry as a method to retain atmospheric CO2 to combat the greenhouse effect. A broad spectrum of alkanolamines and, more recently, their mixtures are being employed for the removal of acid gases such as CO2, H2S, and COS from natural and industrial gas streams. In this research, simultaneous absorption of CO2 and H2S into aqueous blends of N-methyldiethanolamine and diethanolamine is studied theoretically and experimentally. The effect of contact time, temperature, and amine concentration on the rate of absorption and the selectivity were studied by absorption experiments in a wetted wall column at atmospheric pressure and constant feed gas ratio. The diffusion-reaction processes for CO2 and H2S mass transfer in blended amines are modeled according to Higbie's penetration theory with the assumption that all reactions are reversible. A rigorous parametric sensitivity test is done to quantify the effects of possible errors in the pertinent model parameters on the prediction accuracy of the absorption rates and enhancement factors. Model results based on the kinetics-equilibrium-mass transfer coupled model developed in this work are found to be in good agreement with the experimental results of rates of absorption of CO2 and H2S into (MDEA + DEA + H2O).

Temporal Variation of HCO+ 1_0 Galactic Absorption Lines Toward NRAO 150 and BL Lac

NASA Astrophysics Data System (ADS)

Han, Junghwan; Yun, Youngjoo; Park, Yong-Sun

2017-12-01

We present observations of HCO^+ 1-0 absorption lines toward two extragalactic compact radio sources, NRAO 150 and BL Lac with the Korean VLBI Network in order to investigate their time variation over 20 years by Galactic foreground clouds. It is found that the line shape of -17 km s^{-1} component changed marginally during 1993-1998 period and has remained unaltered thereafter for NRAO 150. Its behavior is different from that of H_2CO 1_{10}-1_{11}, suggesting chemical differentiation on ˜ 20 AU scale, the smallest ever seen. On the other hand, BL Lac exhibits little temporal variation for the HCO^+ and H_2CO lines. Our observation also suggests that Korea VLBI Network performs reliably in the spectrum mode in that the shapes of the new HCO^+ 1-0 spectra are in good agreement with the previous ones to an accuracy of a few percent except the time varying component toward NRAO 150.

Fiber-Based Laser Transmitter at 1.57 Micrometers for Remote Sensing of Atmospheric Carbon Dioxide from Satellites

NASA Technical Reports Server (NTRS)

Yu, Anthony W.; Abshire, James B.; Stephen, Mark A.; Chen, Jeffrey R.; Wu, Stewart; Gonzalez, Brayler; Han, Lawrence; Numata, Kenji; Allan, Graham R.; Hasselbrack, William;

Organic fertilizer application increases the soil respiration and net ecosystem carbon dioxide absorption of paddy fields under water-saving irrigation.

PubMed

Yang, Shihong; Xiao, Ya Nan; Xu, Junzeng

2018-04-01

Quantifying carbon sequestration in paddy soil is necessary to understand the effect of agricultural practices on carbon cycles. The objective of this study was to assess the effect of organic fertilizer addition (MF) on the soil respiration and net ecosystem carbon dioxide (CO 2 ) absorption of paddy fields under water-saving irrigation (CI) in the Taihu Lake Region of China during the 2014 and 2015 rice-growing seasons. Compared with the traditional fertilizer and water management (FC), the joint regulation of CI and MF (CM) significantly increased the rice yields and irrigation water use efficiencies of paddy fields by 4.02~5.08 and 83.54~109.97% (p < 0.05). The effects of organic fertilizer addition on soil respiration and net ecosystem CO 2 absorption rates showed inter-annual differences. CM paddy fields showed a higher soil respiration and net CO 2 absorption rates during some periods of the rice growth stage in the first year and during most periods of the rice growth stage in the second year. These fields also had significantly higher total CO 2 emission through soil respiration (total R soil ) and total net CO 2 absorption compared with FC paddy fields (p < 0.05). The total R soil and net ecosystem CO 2 absorption of CM paddy fields were 67.39~91.55 and 129.41~113.75 mol m -2 , which were 27.66~135.52 and 12.96~31.66% higher than those of FC paddy fields. The interaction between water and fertilizer management had significant effects on total net ecosystem CO 2 absorption. The frequent alternate wet-dry cycles of CI paddy fields increased the soil respiration and reduced the net CO 2 absorption. Organic fertilizer promoted the soil respiration of paddy soil but also increased its net CO 2 absorption and organic carbon content. Therefore, the joint regulation of water-saving irrigation and organic fertilizer is an effective measure for maintaining yield, increasing irrigation water use efficiency, mitigating CO 2 emission, and promoting paddy soil fertility.

Carbon Dioxide Absorption by the Imidazolium-Amino Acid Ionic Liquids, Kinetics, and Mechanism Approach.

PubMed

Rezaeian, Mojtaba; Izadyar, Mohammad; Nakhaei Pour, Ali

2018-06-25

The kinetics and mechanism of CO 2 absorption by ionic liquids (ILs) were studied, theoretically. The studied ILs are composed of 1-ethyl-3-methylimidazolium [Emim] + as the cation with a general formula of the [Emim][X] (X = Gly - , Ala - , Lys - , Arg - ). To investigate the alkyl chain length and the number of the amine group effects on the CO 2 absorption, different amino acid anions were chosen. On the basis of the enthalpy changes during CO 2 capture, a chemisorption nature is confirmed. An increase in the number of amine (-NH 2 ) groups in the ILs structures, facilitates the CO 2 absorption. According to kinetic results, the rate of CO 2 absorption by [Emim][Gly] is higher than that of [Emim][Ala]. This can be interpreted by a higher steric hindrance in [Emim][Ala] due to an additional methyl group in the amino acid chain. Donor-acceptor interactions and C-N bond formation were investigated by natural bond orbital analysis. Moreover, topological studies show a covalent nature for the C-N bond critical point that showing CO 2 capture is a chemisorption process. Finally, on the basis of kinetic energy results, donor-acceptor interaction and topological analysis, [Emim][Arg] is proposed as the best candidate for CO 2 absorption from the kinetic and thermodynamic viewpoints.

Performance characteristics and modeling of carbon dioxide absorption by amines in a packed column

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, S.H.; Shyu, C.T.

1999-01-01

Carbon dioxide (CO[sub 2]) is widely recognized as a major greenhouse gas contributing to global warming. To mitigate the global warming problem, removal of CO[sub 2] from the industrial flue gases is necessary. Absorption of carbon dioxide by amines in a packed column was experimentally investigated. The amines employed in the present study were the primary mono-ethanolamine (MEA) and tertiary N-methyldiethanolamine (MDEA), two very popular amines widely used in the industries for gas purification. The CO[sub 2] absorption characteristics by these two amines were experimentally examined under various operating conditions. A theoretical model was developed for describing the CO[sub 2]more » absorption behavior. Test data have revealed that the model predictions and the observed CO[sub 2] absorption breakthrough curves agree very well, validating the proposed model. Preliminary regeneration tests of exhausted amine solution were also conducted. The results indicated that the tertiary amine is easier to regenerate with less loss of absorption capacity than the primary one.« less

Infrared spectra of the CO2- and C2O4- anions isolated in solid argon

NASA Astrophysics Data System (ADS)

Zhou, Mingfei; Andrews, Lester

1999-02-01

Laser ablation of transition metal targets with concurrent 11 to 12 K condensation of CO2-Ar mixtures produces a sharp metal independent infrared absorption at 1657.0 cm-1 due to CO2-, which is formed from the capture of ablated electrons by CO2 molecules during the condensation process. Two additional metal independent absorptions are produced at 1856.7 and 1184.7 cm-1 on matrix annealing to 25 K to allow diffusion and reaction of CO2 and CO2-. Isotopic substitution (13CO2, C18O2, C16,18O2, and mixtures) shows that these two vibrations involve two equivalent CO2 subunits. The excellent agreement with frequencies, intensities, and isotopic frequency ratios from density-functional calculations supports assignment to the symmetrical C2O4- anion with D2d symmetry. Photodissociation (470-580 nm) and failure to observe these absorptions in identical experiments doped with the electron trapping molecule CCl4 further support the molecular anion assignments. Although absorptions were observed for weak (CO2)(CO2-) complexes, no evidence was found for the asymmetric O2CṡOCO- molecule-anion complex characterized by calculations.

Direct synthesis and characterization of mixed-valent Li 0.5$-$δCoPO 4, a Li-deficient derivative of the Cmcm polymorph of LiCoPO 4

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ludwig, Jennifer; Alarcon-Suesca, Carlos; Geprags, Stephan

While the majority of research activities on LiCoPO 4 is focussed on the thermodynamically stable olivine-type Pnma polymorph, the metastable Pna2 1 and Cmcm modifications have recently attracted considerable attention due to their interesting material properties. In this study, we present the first Li-deficient structural derivative of the Cmcm modification with the nominal composition Li 0.5–δCoPO 4. As opposed to the substoichiometric olivine ( Pnma) phases Li xCoPO 4 (x = 0; 2/3), which are exclusively accessible by electrochemical or chemical Li extraction techniques, this is also the first time that a direct soft-chemical synthesis route towards a Li xCoPOmore » 4-type material is accomplished. X-ray and neutron diffraction studies indicate that Cmcm-type Li 0.5–δCoPO 4 shows vacancies on both the Li and Co sites, whereas X-ray absorption spectra demonstrate that the structure features heterovalent Co ions (+2/+3) to compensate for the Li deficit. Magnetic measurements reveal a long-range antiferromagnetic order below 10.5 K. A thorough investigation of the thermal stability using thermogravimetric analysis, differential scanning calorimetry, and temperature-dependent in situ X-ray powder diffraction demonstrates that Li 0.5–δCoPO 4 is metastable and exhibits a complex, multi-step thermal decomposition mechanism. In the first step at 394 °C, it decomposes to α-Co 2P 2O 7 ( P2 1/c) and LiCoPO 4 ( Cmcm) upon O 2 release. The LiCoPO 4 ( Cmcm) intermediate is then irreversibly transformed to olivine-type LiCoPO 4 (Pnma) at 686 °C. Furthermore, the material properties of Li 0.5–δCoPO 4 are further compared to the fully lithiated, isostructural LiCoPO 4 ( Cmcm) phase, for which an improved structure solution as well as Co L 2,3-edge X-ray absorption spectra are reported for the first time.« less

Direct synthesis and characterization of mixed-valent Li 0.5$-$δCoPO 4, a Li-deficient derivative of the Cmcm polymorph of LiCoPO 4

DOE PAGES

Ludwig, Jennifer; Alarcon-Suesca, Carlos; Geprags, Stephan; ...

2017-05-26

While the majority of research activities on LiCoPO 4 is focussed on the thermodynamically stable olivine-type Pnma polymorph, the metastable Pna2 1 and Cmcm modifications have recently attracted considerable attention due to their interesting material properties. In this study, we present the first Li-deficient structural derivative of the Cmcm modification with the nominal composition Li 0.5–δCoPO 4. As opposed to the substoichiometric olivine ( Pnma) phases Li xCoPO 4 (x = 0; 2/3), which are exclusively accessible by electrochemical or chemical Li extraction techniques, this is also the first time that a direct soft-chemical synthesis route towards a Li xCoPOmore » 4-type material is accomplished. X-ray and neutron diffraction studies indicate that Cmcm-type Li 0.5–δCoPO 4 shows vacancies on both the Li and Co sites, whereas X-ray absorption spectra demonstrate that the structure features heterovalent Co ions (+2/+3) to compensate for the Li deficit. Magnetic measurements reveal a long-range antiferromagnetic order below 10.5 K. A thorough investigation of the thermal stability using thermogravimetric analysis, differential scanning calorimetry, and temperature-dependent in situ X-ray powder diffraction demonstrates that Li 0.5–δCoPO 4 is metastable and exhibits a complex, multi-step thermal decomposition mechanism. In the first step at 394 °C, it decomposes to α-Co 2P 2O 7 ( P2 1/c) and LiCoPO 4 ( Cmcm) upon O 2 release. The LiCoPO 4 ( Cmcm) intermediate is then irreversibly transformed to olivine-type LiCoPO 4 (Pnma) at 686 °C. Furthermore, the material properties of Li 0.5–δCoPO 4 are further compared to the fully lithiated, isostructural LiCoPO 4 ( Cmcm) phase, for which an improved structure solution as well as Co L 2,3-edge X-ray absorption spectra are reported for the first time.« less

Laser diode absorption spectroscopy for accurate CO(2) line parameters at 2 microm: consequences for space-based DIAL measurements and potential biases.

PubMed

Joly, Lilian; Marnas, Fabien; Gibert, Fabien; Bruneau, Didier; Grouiez, Bruno; Flamant, Pierre H; Durry, Georges; Dumelie, Nicolas; Parvitte, Bertrand; Zéninari, Virginie

2009-10-10

Space-based active sensing of CO(2) concentration is a very promising technique for the derivation of CO(2) surface fluxes. There is a need for accurate spectroscopic parameters to enable accurate space-based measurements to address global climatic issues. New spectroscopic measurements using laser diode absorption spectroscopy are presented for the preselected R30 CO(2) absorption line ((20(0)1)(III)<--(000) band) and four others. The line strength, air-broadening halfwidth, and its temperature dependence have been investigated. The results exhibit significant improvement for the R30 CO(2) absorption line: 0.4% on the line strength, 0.15% on the air-broadening coefficient, and 0.45% on its temperature dependence. Analysis of potential biases of space-based DIAL CO(2) mixing ratio measurements associated to spectroscopic parameter uncertainties are presented.

Absorption sensor for CO in combustion gases using 2.3 µm tunable diode lasers

NASA Astrophysics Data System (ADS)

Chao, X.; Jeffries, J. B.; Hanson, R. K.

2009-11-01

Tunable diode laser absorption spectroscopy of CO was studied in the controlled laboratory environments of a heated cell and a combustion exhaust rig. Two absorption lines, R(10) and R(11) in the first overtone band of CO near 2.3 µm, were selected from a HITRAN simulation to minimize interference from water vapor at a representative combustion exhaust temperature (~1200 K). The linestrengths and collision broadening coefficients for these lines were measured in a heated static cell. This database was then used in a comparative study of direct absorption and wavelength-modulation absorption. CO concentration measurements using scanned-wavelength direct absorption (DA) and wavelength modulation with the second-harmonic signal normalized by the first-harmonic signal (WMS-2f/1f) all agreed with those measured by a conventional gas sampling analyzer over the range from <10 ppm to 2.3%. As expected, water vapor was found to be the dominant source of background interference for CO detection in combustion flows at high temperatures. Water absorption was measured to a high spectral resolution within the wavelength region 4295-4301 cm-1 at 1100 K, and shown to produce <10 ppm level interference for CO detection in combustion exhausts at temperatures up to 1200 K. We found that the WMS-2f/1f strategy avoids the need for WMS calibration measurements but requires characterization of the wavelength and injection-current intensity modulation of the specific diode laser. We conclude that WMS-2f/1f using the selected R(10) or R(11) transitions in the CO overtone band holds good promise for sensitive in situ detection of ppm-level CO in combustion flows, with high resistance to interference absorption from H2O.

Preparation and in vitro/in vivo Evaluation of Lacidipine by Adsorption onto Fumed Silica Using Supercritical Carbon Dioxide.

PubMed

Geng, Yajie; Fu, Qiang; Guo, Bei; Li, Yun; Zhang, Xiangrong; Wang, Xianglin; Zhang, Tianhong

2016-01-01

The aim of this study was to design a silica-supported solid dispersion of lacidipine (LCDP) to enhance the dissolution rate and oral absorption using supercritical CO2 (scCO2) as a solvent. The formulation was characterized using differential scanning calorimetry, powder X-ray diffraction, scanning electron microscopy and fourier transformed infrared spectroscopy. In the dissolution test, LCDP-scCO2 formulation showed a significantly enhanced dissolution compared with LCDPsilica physical mixture and a faster dissolution rate than Lacipil® under different dissolution conditions. In an in vivo test, the area under concentration-time curve and Cmax of LCDP-scCO2 formulation was 9.23 and 23.78 fold greater than LCDP-silica physical mixture (1:15, w/w), respectively, whereas the corresponding values were 1.92 and 2.80 fold greater than Lacipil®, respectively. Our results showed that the solid dispersion prepared by supercritical fluids technology is a feasible method to enhance the oral bioavailability of LCDP.

A Preliminary Study of CO2 Flux Measurements by Lidar

NASA Technical Reports Server (NTRS)

Gibert, Fabien; Koch, Grady J.; Beyon, Jeffrey Y.; Hilton, T.; Davis, Kenneth J.; Andrews, Arlyn; Ismail, Syed; Singh, Upendra N.

2008-01-01

A mechanistic understanding of the global carbon cycle requires quantification of terrestrial ecosystem CO2 fluxes at regional scales. In this paper, we analyze the potential of a Doppler DIAL system to make flux measurements of atmospheric CO2 using the eddy-covariance and boundary layer budget methods and present results from a ground based experiment. The goal of this study is to put CO2 flux point measurements in a mesoscale context. In June 2007, a field experiment combining a 2-m Doppler Heterodyne Differential Absorption Lidar (HDIAL) and in-situ sensors of a 447-m tall tower (WLEF) took place in Wisconsin. The HDIAL measures simultaneously: 1) CO2 mixing ratio, 2) atmosphere structure via aerosol backscatter and 3) radial velocity. We demonstrate how to synthesize these data into regional flux estimates. Lidar-inferred fluxes are compared with eddy-covariance fluxes obtained in-situ at 396m AGL from the tower. In cases where the lidar was not yet able to measure the fluxes with acceptable precision, we discuss possible modifications to improve system performance.

Turbulent CO2 Flux Measurements by Lidar: Length Scales, Results and Comparison with In-Situ Sensors

NASA Technical Reports Server (NTRS)

Gilbert, Fabien; Koch, Grady J.; Beyon, Jeffrey Y.; Hilton, Timothy W.; Davis, Kenneth J.; Andrews, Arlyn; Ismail, Syed; Singh, Upendra N.

2009-01-01

The vertical CO2 flux in the atmospheric boundary layer (ABL) is investigated with a Doppler differential absorption lidar (DIAL). The instrument was operated next to the WLEF instrumented tall tower in Park Falls, Wisconsin during three days and nights in June 2007. Profiles of turbulent CO2 mixing ratio and vertical velocity fluctuations are measured by in-situ sensors and Doppler DIAL. Time and space scales of turbulence are precisely defined in the ABL. The eddy-covariance method is applied to calculate turbulent CO2 flux both by lidar and in-situ sensors. We show preliminary mean lidar CO2 flux measurements in the ABL with a time and space resolution of 6 h and 1500 m respectively. The flux instrumental errors decrease linearly with the standard deviation of the CO2 data, as expected. Although turbulent fluctuations of CO2 are negligible with respect to the mean (0.1 %), we show that the eddy-covariance method can provide 2-h, 150-m range resolved CO2 flux estimates as long as the CO2 mixing ratio instrumental error is no greater than 10 ppm and the vertical velocity error is lower than the natural fluctuations over a time resolution of 10 s.

Far-infrared spectra of CO2 clathrate hydrate frosts

NASA Technical Reports Server (NTRS)

Landry, J. C.; England, A. W.

1993-01-01

As a product of our interest in remote sensing of planetary ices, frost samples of CO2 clathrate hydrate were grown by depositing water vapor on a cooled surface and pressurizing the resulting water frost with CO2 gas. At pressures above the dissociation pressure of the clathrate, the samples exhibit an absorption peak at 75 cm (sup -1). At pressures below the dissociation pressure, the peak disappears. Since the free CO2 molecule does not have rotational or vibrational absorption in this region, the absorption is attributed to a CO2 rattling mode within a clathrate cage.

[Determination of trace cobalt in human urine by graphite furnace atomic absorption spectrometr].

PubMed

Zhong, L X; Ding, B M; Jiang, D; Liu, D Y; Yu, B; Zhu, B L; Ding, L

2016-05-20

To establish a method to determine cobalt in human urine by graphite furnace atomic absorption spectrometry. Urine with 2% nitric acid diluted two-fold, to quantify the curve, graphite furnace atomic absorption spectrometric detection. Co was linear within 2.5~40.0 ng/ml with r>0.999. Spike experiment showed that Co received good recovery rate, which was 90.8%~94.8%. Intra-assay precisions were 3.2%~5.1% for Co, inter-assay precisions were 4.4%~5.2% for Co. The method by using graphite furnace atomic absorption spectrometr to determine urine Co was fast, accurate and with low matrix effect. It could meet the requirement in GBZ/T 210.5-2008.

Development of an Eye-Safe Micro-Pulse Differential Absorption Lidar (DIAL) for Carbon Dioxide Profilings

NASA Astrophysics Data System (ADS)

Johnson, W.; Repasky, K. S.; Nehrir, A. R.; Carlsten, J.

2011-12-01

A differential absorption lidar (DIAL) for monitoring carbon dioxide (CO2) is under development at Montana State University using commercially available parts. Two distributed feedback (DFB) lasers, one at the on-line wavelength and one at the off-line wavelength are used to injection seed a fiber amplifier. The DIAL operates in the 1.57 micron carbon dioxide absorption band at an on-line wavelength of 1.5714060 microns. The laser transmitter produces 40 μJ pulses with a pulse duration of 1 μs and a pulse repetition frequency of 20 kHz. The scattered light from the laser transmitter is collected using a 28 cm diameter Schmidt-Cassegrain telescope. The light collected by the telescope is collimated and then filtered using a 0.8 nm FWHM narrowband interference filter. After the optical filter, the light is coupled into a multimode optical fiber with a 1000 μm core diameter. The output from the optical fiber is coupled into a photomultiplier tube (PMT) used to monitor the return signal. The analog output from the PMT is next incident on a discriminator producing TTL logic pulses for photon counting. The output from the PMT and discriminator is monitored using a multichannel scalar card allowing the counting of the TTL pulses as a function of range. Data from the DIAL instrument is collected in the following manner. The fiber amplifier is injection seeded first with the on-line DFB laser. The return signal as a function of range is integrated using the multichannel scalar for a user defined time, typically set at 6 s. The off-line DFB laser is then used to injection seed the fiber amplifier and the process is repeated. This process is repeated for a user defined period. The CO2 concentration as a function of range is calculated using the on-line and off-line return signals with the DIAL equation. A comparison of the CO2 concentration measured using the DIAL instrument at 1.5 km and a Li-Cor LI-820 in situ sensor located at 1.5 km from the DIAL over a 2.5 hour period indicate that the CO2 DIAL has an accuracy of ±20 parts per million (PPM).

Development of a Fabry-Perot Interferometer for Ultra-Precise Measurements of Column CO2

NASA Technical Reports Server (NTRS)

Wilson, Emily L.; Georgieva, Elena M.; Heaps, William S.

2005-01-01

A passive Fabry-Perot based instrument is described for detecting column CO2 through absorption measurements at 1.58 microns . In this design, solar flux reaches the instrument platform and is directed through two channels. In the first channel, transmittance fi5nges from a Fabry-Perot interferometer are aligned with CO2 absorption lines so that absorption due to CO2 is primarily detected. The second channel encompasses the same frequency region as the first, but is comparatively more sensitive to changes in the solar flux than absorption due to CO2. The ratio of these channels is sensitive to changes in the total CO2 column, but not to changes in solar flux. This inexpensive instrument will offer high precision measurements (error 4%) in a compact package. Design of this instrument and preliminary ground-based measurements of column CO2 are presented here as well as strategies for deployment on aircraft and satellite platforms.

Calibrating Laser Gas Measurements by Use of Natural CO2

NASA Technical Reports Server (NTRS)

Webster, Chris

2003-01-01

An improved method of calibration has been devised for instruments that utilize tunable lasers to measure the absorption spectra of atmospheric gases in order to determine the relative abundances of the gases. In this method, CO2 in the atmosphere is used as a natural calibration standard. Unlike in one prior calibration method, it is not necessary to perform calibration measurements in advance of use of the instrument and to risk deterioration of accuracy with time during use. Unlike in another prior calibration method, it is not necessary to include a calibration gas standard (and the attendant additional hardware) in the instrument and to interrupt the acquisition of atmospheric data to perform calibration measurements. In the operation of an instrument of this type, the beam from a tunable diode laser or a tunable quantum-cascade laser is directed along a path through the atmosphere, the laser is made to scan in wavelength over an infrared spectral region that contains one or two absorption spectral lines of a gas of interest, and the transmission (and, thereby, the absorption) of the beam is measured. The concentration of the gas of interest can then be calculated from the observed depth of the absorption line(s), given the temperature, pressure, and path length. CO2 is nearly ideal as a natural calibration gas for the following reasons: CO2 has numerous rotation/vibration infrared spectral lines, many of which are near absorption lines of other gases. The concentration of CO2 relative to the concentrations of the major constituents of the atmosphere is well known and varies slowly and by a small enough amount to be considered constant for calibration in the present context. Hence, absorption-spectral measurements of the concentrations of gases of interest can be normalized to the concentrations of CO2. Because at least one CO2 calibration line is present in every spectral scan of the laser during absorption measurements, the atmospheric CO2 serves continuously as a calibration standard for every measurement point. Figure 1 depicts simulated spectral transmission measurements in a wavenumber range that contains two absorption lines of N2O and one of CO2. The simulations were performed for two different upper-atmospheric pressures for an airborne instrument that has a path length of 80 m. The relative abundance of CO2 in air was assumed to be 360 parts per million by volume (approximately its natural level in terrestrial air). In applying the present method to measurements like these, one could average the signals from the two N2O absorption lines and normalize their magnitudes to that of the CO2 absorption line. Other gases with which this calibration method can be used include H2O, CH4, CO, NO, NO2, HOCl, C2H2, NH3, O3, and HCN. One can also take advantage of this method to eliminate an atmospheric-pressure gauge and thereby reduce the mass of the instrument: The atmospheric pressure can be calculated from the temperature, the known relative abundance of CO2, and the concentration of CO2 as measured by spectral absorption. Natural CO2 levels on Mars provide an ideal calibration standard. Figure 2 shows a second example of the application of this method to Mars atmospheric gas measurements. For sticky gases like H2O, the method is particularly powerful, since water is notoriously difficult to handle at low concentrations in pre-flight calibration procedures.

Column carbon dioxide and water vapor measurements by an airborne triple-pulse integrated path differential absorption lidar: novel lidar technologies and techniques with path to space

NASA Astrophysics Data System (ADS)

Singh, U. N.; Petros, M.; Refaat, T. F.; Yu, J.; Ismail, S.

2017-09-01

The 2-micron wavelength region is suitable for atmospheric carbon dioxide (CO2) measurements due to the existence of distinct absorption features for the gas at this wavelength region [1]. For more than 20 years, researchers at NASA Langley Research Center (LaRC) have developed several high-energy and high repetition rate 2-micron pulsed lasers [2]. Currently, LaRC team is engaged in designing, developing and demonstrating a triple-pulsed 2-micron direct detection Integrated Path Differential Absorption (IPDA) lidar to measure the weighted-average column dry-air mixing ratios of carbon dioxide (XCO2) and water vapor (XH2O) from an airborne platform [1, 3-5]. This novel technique allows measurement of the two most dominant greenhouse gases, simultaneously and independently, using a single instrument. This paper will provide status and details of the development of this airborne 2-micron triple-pulse IPDA lidar. The presented work will focus on the advancement of critical IPDA lidar components. Updates on the state-of-the-art triple-pulse laser transmitter will be presented including the status of seed laser locking, wavelength control, receiver and detector upgrades, laser packaging and lidar integration. Future plans for IPDA lidar ground integration, testing and flight validation will also be discussed. This work enables new Earth observation measurements, while reducing risk, cost, size, volume, mass and development time of required instruments.

Kinetics of absorption of CO{sub 2} in concentrated aqueous methyldiethanolamine solutions in the range 296 K to 343 K

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pani, F.; Gaunand, A.; Cadours, R.

1997-03-01

The kinetics of CO{sub 2} absorption by aqueous solutions of methyl diethanol amine (MDEA) were measured in the temperature range (296--343) K and MDEA concentration range (830--4,380) mol/m{sup 3} (10--50 mass %). A thermoregulated constant interfacial area Lewis-type cell was operated by recording the pressure drop during batch absorption. The kinetic results are in agreement with a fast regime of absorption according to film theory. MDEA depletion at the interface has a significant effect on the kinetics at the CO{sub 2} pressures (100 to 200 kPa) studied in this work, especially at low temperatures and low MDEA concentrations. Considering onlymore » the reaction between CO{sub 2} and MDEA, the CO{sub 2} absorption appears as a first-order reaction with respect to MDEA. The activation energy found for the reaction between CO{sub 2} and MDEA is 45 kJ/mol, but this value depends significantly (by about 10% in the worst case) on the vapor-liquid equilibrium data used.« less

The CO2 absorption spectrum in the 2.3 μm transparency window by high sensitivity CRDS: (II) Self-absorption continuum

NASA Astrophysics Data System (ADS)

Mondelain, D.; Vasilchenko, S.; Čermák, P.; Kassi, S.; Campargue, A.

2017-01-01

The CO2 absorption continuum near 2.3 μm is determined for a series of sub atmospheric pressures (250-750 Torr) by high sensitivity Cavity Ring Down Spectroscopy. An experimental procedure consisting in injecting successively a gas flow of CO2 and synthetic air, keeping constant the gas pressure in the CRDS cell, has been developed. This procedure insures a high stability of the spectra baseline by avoiding changes of the optical alignment due to pressure changes. The CO2 continuum was obtained as the difference between the CO2 absorption coefficient and a local lines simulation using a Voigt profile truncated at ±25 cm-1. Following the results of the preceding analysis of the CO2 rovibrational lines (Vasilchenko S et al. J Quant Spectrosc Radiat Transfer 10.1016/j.jqsrt.2016.07.002, a CO2 line list with intensities obtained by variational calculations and empirical line positions was preferred to the HITRAN line list. A quadratic pressure dependence of the absorption continuum is observed, with an average binary absorption coefficient increasing from 2 to 4×10-8 cm-1 amagat-2 between 4320 and 4380 cm-1. The obtained continuum is found in good agreement with a previous measurement using much higher densities (20 amagat) and a low resolution grating spectrograph and is consistent with values currently used in the analysis of Venus spectra.

ACCURATE: Greenhouse Gas Profiles Retrieval from Combined IR-Laser and Microwave Occultation Measurements

NASA Astrophysics Data System (ADS)

Proschek, Veronika; Kirchengast, Gottfried; Schweitzer, Susanne; Fritzer, Johannes

2010-05-01

The new climate satellite concept ACCURATE (Atmospheric Climate and Chemistry in the UTLS Region And climate Trends Explorer) enables simultaneous measurement of profiles of greenhouse gases, isotopes, wind and thermodynamic variables from Low Earth Orbit (LEO) satellites. The measurement principle applied is a combination of the novel LEO-LEO infrared laser occultation (LIO) technique and the already better studied LEO-LEO microwave occultation (LMO) technique. Resulting occultation events are evenly distributed around the world, have high vertical resolution and accuracy and are stable over long time periods. The LIO uses near-monochromatic signals in the short-wave infrared range (~2-2.5 μm for ACCURATE). These signals are absorbed by various trace species in the Earth's atmosphere. Profiles of the concentration of the absorbing species can be derived from signal transmission measurements. Accurately known temperature, pressure and humidity profiles derived from simultaneously measured LMO signals are essential pre-information for the retrieval of the trace species profiles. These LMO signals lie in the microwave band region from 17-23 GHz and, optionally, 178-195 GHz. The current ACCURATE mission design is arranged for the measurement of six greenhouse gases (GHG) (H2O, CO2, CH4, N2O, O3, CO) and four isotopes (13CO2, C18OO, HDO, H218O), with focus on the upper troposphere/lower stratosphere region (UTLS, 5-35 km). Wind speed in line-of-sight can be derived from a line-symmetric transmission difference which is caused by wind-induced Doppler shift. By-products are information on cloud layering, aerosol extinction, and scintillation strength. We introduce the methodology to retrieve GHG profiles from quasi-realistic forward-simulated intensities of LIO signals and thermodynamic profiles retrieved in a preceding step from LMO signals. Key of the retrieval methodology is the differencing of two LIO transmission signals, one being GHG sensitive on a target absorption line and one being a close-by reference outside of any absorption lines. The reference signal is used to remove atmospheric broadband" effects by this differential absorption" approach. Refractivity and impact parameter of the LIO signals, needed for the retrieval, can be computed from the LMO-derived thermodynamic profiles. An Abel Transform converts the differential LIO log-transmission profile to the absorption coefficient. Based on the absorption coefficient and the absorption cross section of the GHG under investigation, that can as well be computed from the LMO-derived profiles, the number density profile or volume mixing ratio of the desired GHG can be finally derived. When using several LIO signals, best sensitive to the same GHG at different heights, a joint optimal GHG profile can be constructed by combining the individual profiles in an inverse-variance-weighted manner (practically used for H2O, obtained from 3-4 signals, and for CO2, obtained from 2 isotope signals). The thermodynamic parameters (temperature, pressure and humidity) derived from LMO as basis for the LIO retrieval are found to be accurate to better than 0.5 K for temperature, 0.2% for pressure, and 10% for humidity. The accuracy of retrieved trace species profiles is found better than 1% to 4% for single profiles in the UTLS region (outside clouds which block infrared) and the profiles are essentially unbiased (biases

Stratospheric CH4 and CO2 profiles derived from SCIAMACHY solar occultation measurements

NASA Astrophysics Data System (ADS)

Noël, Stefan; Bramstedt, Klaus; Hilker, Michael; Liebing, Patricia; Plieninger, Johannes; Reuter, Max; Rozanov, Alexei; Sioris, Christopher E.; Bovensmann, Heinrich; Burrows, John P.

2016-04-01

Stratospheric profiles of methane (CH4) and carbon dioxide (CO2) have been derived from solar occultation measurements of the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY). The retrieval is performed using a method called onion peeling DOAS (ONPD), which combines an onion peeling approach with a weighting function DOAS (differential optical absorption spectroscopy) fit in the spectral region between 1559 and 1671 nm. By use of updated pointing information and optimisation of the data selection as well as of the retrieval approach, the altitude range for reasonable CH4 could be broadened from 20 to 40 km to about 17 to 45 km. Furthermore, the quality of the derived CO2 has been assessed such that now the first stratospheric profiles (17-45 km) of CO2 from SCIAMACHY are available. Comparisons with independent data sets yield an estimated accuracy of the new SCIAMACHY stratospheric profiles of about 5-10 % for CH4 and 2-3 % for CO2. The accuracy of the products is currently mainly restricted by the appearance of unexpected vertical oscillations in the derived profiles which need further investigation. Using the improved ONPD retrieval, CH4 and CO2 stratospheric data sets covering the whole SCIAMACHY time series (August 2002-April 2012) and the latitudinal range between about 50 and 70° N have been derived. Based on these time series, CH4 and CO2 trends have been estimated. CH4 trends above about 20 km are not significantly different from zero and the trend at 17 km is about 3 ppbv year-1. The derived CO2 trends show a general decrease with altitude with values of about 1.9 ppmv year-1 at 21 km and about 1.3 ppmv year-1 at 39 km. These results are in reasonable agreement with total column trends for these gases. This shows that the new SCIAMACHY data sets can provide valuable information about the stratosphere.

From Layered Structures to Cubic Frameworks. Expanding the Structural Diversity of Uranyl Carboxyphosphonates via the Incorporation of Cobalt

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alsobrook, Andrea N.; Hauser, Brad G.; Hupp, Joseph T.

2011-02-08

Five heterobimetallic U(VI)/Co(II) carboxyphosphonates have been synthesized under mild hydrothermal conditions by reacting UO 3, Co(CH 3CO 2) 2·4H 2O, and triethyl phosphonoacetate. These compounds, Co(H 2O) 4[(UO 2) 2(PO 3CH 2CO 2) 2(H 2O) 2] (CoUPAA-1), [Co(H 2O) 6][UO 2(PO 3CH 2CO 2)] 2·8H 2O (CoUPAA-2), Co(H 2O) 4[UO 2(PO 3CH 2CO 2)] 2·4H 2O (CoUPAA-3), Co(H 2O) 4[(UO 2) 62CH 2CO 2) 2O 2(OH) 3(H 2O) 3] 2·3H 2O (CoUPAA-4), and Co 2(UO 2) 6(PO 3CH 2CO 2) 3O 3(OH)(H 2O) 2·16H 2O (CoUPAA-5), range from two- to three-dimensional structures. CoUPAA-1 to CoUPAA-3 all possess uranyl carboxyphosphonate layersmore » that are separated by the Co(II) cation with varying degrees of hydration. CoUPAA-4 contains both UO 7 pentagonal bipyramids and UO 8 hexagonal bipyramids within the uranyl carboxyphosphonate plane. Unlike the first four low-symmetry compounds, CoUPAA-5 is a cubic, three-dimensional network with large cavities approximately 16 Å in diameter that are filled with cocrystallized water molecules. Differential gas absorption measurements performed on CoUPAA-5 displayed a surface area uptake for CO 2 of 40 m 2 g -1 at 273 K, and no uptake for N 2 at 77 K.« less

Surfactant-assisted hydrothermal crystallization of nanostructured lithium metasilicate (Li{sub 2}SiO{sub 3}) hollow spheres: II-Textural analysis and CO{sub 2}-H{sub 2}O sorption evaluation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ortiz-Landeros, Jose; Gomez-Yanez, Carlos; Pfeiffer, Heriberto, E-mail: pfeiffer@iim.unam.mx

In a previous work, the synthesis and structural-microstructural characterization of different nanocrystalline lithium metasilicate (Li{sub 2}SiO{sub 3}) samples were performed. Then, in this work, initially, a textural analysis was performed over the same samples. Li{sub 2}SiO{sub 3} samples prepared with a non-ionic surfactant (TRITON X-114) presented the best textural properties. Therefore, this sample was selected to evaluate its water vapor (H{sub 2}O) and carbon dioxide (CO{sub 2}) sorption properties. Sorption experiments were performed at low temperatures (30-80 deg. C) in presence of water vapor using N{sub 2} or CO{sub 2} as carrier gases. Results clearly evidenced that CO{sub 2} sorptionmore » on these materials is highly improved by H{sub 2}O vapor, and of course, textural properties enhanced the H{sub 2}O-CO{sub 2} sorption efficiency, in comparison with the solid-state reference sample. - Graphical abstract: Li{sub 2}SiO{sub 3} varied significantly its capacity of CO{sub 2} absorption as a function of the microstructural properties and by the water presence. Highlights: > We studied the CO{sub 2} absorption on different Li{sub 2}SiO{sub 3} samples in presence of H{sub 2}O vapor. > It was proved that CO{sub 2} absorption on Li{sub 2}SiO{sub 3} is controlled by different factors. > Li{sub 2}SiO{sub 3} with a porous microstructure produces a higher CO{sub 2} absorption. > H{sub 2}O vapor favors the CO{sub 2} absorption on Li{sub 2}SiO{sub 3} due to a surface hydroxylation.« less

Laser-induced free-free transitions in elastic electron scattering from CO2

NASA Astrophysics Data System (ADS)

Musa, Mohamed; MacDonald, Amy; Tidswell, Lisa; Holmes, Jim; St. Francis Xavier Laser Scattering Lab Team

2011-03-01

This report presents measurements of laser-induced free-free transitions of electrons scattered from CO2 molecules in the ground electronic state at incident electron energies of 3.8 and 5.8 eV under pulsed CO2 laser field. The differential cross section of free-free transitions involving absorption and emission of up to two photons were measured at various scattering angles with the polarization of the laser either parallel with or perpendicular to the the momentum change vector of the scattered electrons. The results of the parallel geometry are found to be in qualitative agreement with the predictions of the Kroll-Watson approximation within the experimental uncertainty whereas those of the perpendicular geometry show marked discrepancy with the Kroll-Watson predictions. This work was supported by the Natural Sciences and Engineering Research Council of Canada and the St. Francis Xavier University Council for Research.

Improving CO2 permeation and separation performance of CO2-philic polymer membrane by blending CO2 absorbents

NASA Astrophysics Data System (ADS)

Cheng, Jun; Hu, Leiqing; Li, Yannan; Liu, Jianzhong; Zhou, Junhu; Cen, Kefa

2017-07-01

To research effects of CO2 absorption capacity and type of CO2 absorbent on the CO2 separation and free-volume properties of facilitated transport membranes, two types of CO2 absorbents, namely monoethanolamine (MEA) and ionic liquids (ILs:[P66614][Triz] and [P66614][2-Op]), were adopted. The CO2 absorption capacities of MEA, [P66614][Triz] and [P66614][2-Op] were about 0.561 mol CO2 per mol, 0.95 mol CO2 per mol and 1.60 mol CO2 per mol, respectively. All mean free-volume hole radiuses of membranes decreased after blending CO2 absorbents. After polymer membrane blended with two ILs, number of free-volume hole increased, resulting in modest increase of the fractional free volume. Both CO2 permeability and selectivity increased after blending MEA and ILs. The increasing range of CO2 permeability corresponded with CO2 absorption capacity of CO2 absorbents, and membrane blending with [P66614][2-Op] showed the highest CO2 permeability of 672.1 Barrers at 25 °C. Pebax/PEGDME membrane blending with MEA obtained the highest CO2/H2 and CO2/CH4 selectivity at 17.8 and 20.5, respectively.

Infrared absorption of carbon dioxide at high densitites with application to the atmosphere of Venus. Ph.D. Thesis - Columbia Univ.

NASA Technical Reports Server (NTRS)

Moore, J. F.

1971-01-01

Several new infrared absorptions were found in carbon dioxide. All are normally forbidden, and were collision-induced in an absorbing cell whose combination of pressure and path length has a unique sensitivity for induced absorptions. The new absorptions in the 2.3 micron region are attributed to transitions from ground to the 3(1)1 Fermi pair at 4248 and 4391/cm. Other absorptions are attributed to simultaneous CO2-N2 transitions and to the 00(0)0-00(0)2 transition in CO2 polarizability derivatives and regular progressions in strength versus increasing quantum number. The spectra were used to predict the radiative transfer in a dry CO2 model of the lower Venus atmosphere. The results indicate that the radiation balance in the lower atmosphere is adequately explained by a dry massive atmosphere of CO2 with a layer of infrared-opaque clouds. The absorptions in the 2.3 micron region are significant in accounting for the opacity to sustain Venus' 768 K surface temperature.

Rational Construction of Uniform CoNi-Based Core-Shell Microspheres with Tunable Electromagnetic Wave Absorption Properties.

PubMed

Chen, Na; Jiang, Jian-Tang; Xu, Cheng-Yan; Yan, Shao-Jiu; Zhen, Liang

2018-02-16

Core-shell particles with integration of ferromagnetic core and dielectric shell are attracting extensive attention for promising microwave absorption applications. In this work, CoNi microspheres with conical bulges were synthesized by a simple and scalable liquid-phase reduction method. Subsequent coating of dielectric materials was conducted to acquire core-shell structured CoNi@TiO 2 composite particles, in which the thickness of TiO 2 is about 40 nm. The coating of TiO 2 enables the absorption band of CoNi to effectively shift from K u to S band, and endows CoNi@TiO 2 microspheres with outstanding electromagnetic wave absorption performance along with a maximum reflection loss of 76.6 dB at 3.3 GHz, much better than that of bare CoNi microspheres (54.4 dB at 17.8 GHz). The enhanced EMA performance is attributed to the unique core-shell structures, which can induce dipole polarization and interfacial polarization, and tune the dielectric properties to achieve good impedance matching. Impressively, TiO 2 coating endows the composites with better microwave absorption capability than CoNi@SiO 2 microspheres. Compared with SiO 2 , TiO 2 dielectric shells could protect CoNi microspheres from merger and agglomeration during annealed. These results indicate that CoNi@TiO 2 core-shell microspheres can serve as high-performance absorbers for electromagnetic wave absorbing application.

Spectral purity study for IPDA lidar measurement of CO2

NASA Astrophysics Data System (ADS)

Ma, Hui; Liu, Dong; Xie, Chen-Bo; Tan, Min; Deng, Qian; Xu, Ji-Wei; Tian, Xiao-Min; Wang, Zhen-Zhu; Wang, Bang-Xin; Wang, Ying-Jian

2018-02-01

A high sensitivity and global covered observation of carbon dioxide (CO2) is expected by space-borne integrated path differential absorption (IPDA) lidar which has been designed as the next generation measurement. The stringent precision of space-borne CO2 data, for example 1ppm or better, is required to address the largest number of carbon cycle science questions. Spectral purity, which is defined as the ratio of effective absorbed energy to the total energy transmitted, is one of the most important system parameters of IPDA lidar which directly influences the precision of CO2. Due to the column averaged dry air mixing ratio of CO2 is inferred from comparison of the two echo pulse signals, the laser output usually accompanied by an unexpected spectrally broadband background radiation would posing significant systematic error. In this study, the spectral energy density line shape and spectral impurity line shape are modeled as Lorentz line shape for the simulation, and the latter is assumed as an unabsorbed component by CO2. An error equation is deduced according to IPDA detecting theory for calculating the system error caused by spectral impurity. For a spectral purity of 99%, the induced error could reach up to 8.97 ppm.

New ground-based lidar enables volcanic CO2 flux measurements.

PubMed

Aiuppa, Alessandro; Fiorani, Luca; Santoro, Simone; Parracino, Stefano; Nuvoli, Marcello; Chiodini, Giovanni; Minopoli, Carmine; Tamburello, Giancarlo

2015-09-01

There have been substantial advances in the ability to monitor the activity of hazardous volcanoes in recent decades. However, obtaining early warning of eruptions remains challenging, because the patterns and consequences of volcanic unrests are both complex and nonlinear. Measuring volcanic gases has long been a key aspect of volcano monitoring since these mobile fluids should reach the surface long before the magma. There has been considerable progress in methods for remote and in-situ gas sensing, but measuring the flux of volcanic CO2-the most reliable gas precursor to an eruption-has remained a challenge. Here we report on the first direct quantitative measurements of the volcanic CO2 flux using a newly designed differential absorption lidar (DIAL), which were performed at the restless Campi Flegrei volcano. We show that DIAL makes it possible to remotely obtain volcanic CO2 flux time series with a high temporal resolution (tens of minutes) and accuracy (<30%). The ability of this lidar to remotely sense volcanic CO2 represents a major step forward in volcano monitoring, and will contribute improved volcanic CO2 flux inventories. Our results also demonstrate the unusually strong degassing behavior of Campi Flegrei fumaroles in the current ongoing state of unrest.

Kinetics of the Absorption of CO{sub 2} in Aqueous Solutions of N-Methyldiethanolamine plus Triethylene Tetramine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Amann, J.M.G.; Bouallou, C.

2009-04-15

This work focuses on the development of a new solvent for CO{sub 2} capture. This new solvent is an aqueous solution with a blend of N-methyldiethanolamine (MDEA) and triethylene tetramine (TETA), an amine with four amino groups. CO{sub 2} absorption was investigated between 298 and 333 K using a Lewis cell with a constant interfacial area. Several concentrations of MDEA (17.5 and 40 wt %) and TETA (3 and 6 wt %) were assessed. The influence of the CO{sub 2} partial pressure on the absorption rate was pointed out. The addition of small amount of TETA leads to a highmore » increase in the CO{sub 2} absorption rates. A numerical model based on the film theory was used to determine the rate coefficients between CO{sub 2} and TETA for the different solvents. The physicochemical parameters have a huge influence on the determination of the rate coefficients.« less

Fiber-coupled 2.7 µm laser absorption sensor for CO2 in harsh combustion environments

NASA Astrophysics Data System (ADS)

Spearrin, R. M.; Goldenstein, C. S.; Jeffries, J. B.; Hanson, R. K.

2013-05-01

A tunable diode laser absorption sensor near 2.7 µm, based on 1f-normalized wavelength-modulation spectroscopy with second-harmonic detection (WMS-2f), was developed to measure CO2 concentration in harsh combustion flows. Wavelength selection at 3733.48 cm-1 exploited the overlap of two CO2 transitions in the ν1 + ν3 vibrational band at 3733.468 cm-1 and 3733.498 cm-1. Primary factors influencing wavelength selection were isolation and strength of the CO2 absorption lines relative to infrared water absorption at elevated pressures and temperatures. The HITEMP 2010 database was used to model the combined CO2 and H2O absorption spectra, and key line-strength and line-broadening spectroscopic parameters were verified by high-temperature static cell measurements. To validate the accuracy and precision of the WMS-based sensor, measurements of CO2 concentration were carried out in non-reactive shock-tube experiments (P ˜ 3-12 atm, T ˜ 1000-2600 K). The laser was then free-space fiber-coupled with a zirconium fluoride single-mode fiber for remote light delivery to harsh combustion environments, and demonstrated on an ethylene/air pulse detonation combustor at pressures up to 10 atm and temperatures up to 2500 K. To our knowledge, this work represents the first time-resolved in-stream measurements of CO2 concentration in a detonation-based engine.

A compact high repetition rate CO2 coherent Doppler lidar

NASA Technical Reports Server (NTRS)

Alejandro, S.; Frelin, R.; Dix, B.; Mcnicholl, P.

1992-01-01

As part of its program to develop coherent heterodyne detection lidar technology for space, airborne, and ground based applications, the Optical Environment Division of the USAF's Phillips Laboratory developed a compact coherent CO2 TEA lidar system. Although originally conceived as a high altitude balloon borne system, the lidar is presently integrated into a trailer for ground based field measurements of aerosols and wind fields. In this role, it will also serve as a testbed for signal acquisition and processing development for planned future airborne and space based solid state lidar systems. The system has also found significance in new areas of interest to the Air Force such as cloud studies and coherent Differential Absorption Lidar (DIAL) systems.

Advances in High Energy Solid-State Pulsed 2-Micron Lidar Development for Ground and Airborne Wind, Water Vapor and CO2 Measurements

NASA Technical Reports Server (NTRS)

Singh, Upendra N.; Yu, Jirong; Petros, Mulugeta; Refaat, Tamer; Kavaya, Michael J.; Remus, Ruben

2015-01-01

NASA Langley Research Center has a long history of developing 2-micron lasers. From fundamental spectroscopy research, theoretical prediction of new materials, laser demonstration and engineering of lidar systems, it has been a very successful program spanning around two decades. Successful development of 2-micron lasers has led to development of a state-of-the-art compact lidar transceiver for a pulsed coherent Doppler lidar system for wind measurement with an unprecedented laser pulse energy of 250 millijoules in a rugged package. This high pulse energy is produced by a Ho:Tm:LuLiF laser with an optical amplifier. While the lidar is meant for use as an airborne instrument, ground-based tests were carried out to characterize performance of the lidar. Atmospheric measurements will be presented, showing the lidar's capability for wind measurement in the atmospheric boundary layer and free troposphere. Lidar wind measurements are compared to a balloon sonde, showing good agreement between the two sensors. Similar architecture has been used to develop a high energy, Ho:Tm:YLF double-pulsed 2-micron Integrated Differential Absorption Lidar (IPDA) instrument based on direct detection technique that provides atmospheric column CO2 measurements. This instrument has been successfully used to measure atmospheric CO2 column density initially from a ground mobile lidar trailer, and then it was integrated on B-200 plane and 20 hours of flight measurement were made from an altitude ranging 1500 meters to 8000 meters. These measurements were compared to in-situ measurements and National Oceanic and Atmospheric Administration (NOAA) airborne flask measurement to derive the dry mixing ratio of the column CO2 by reflecting the signal by various reflecting surfaces such as land, vegetation, ocean surface, snow and sand. The lidar measurements when compared showed a very agreement with in-situ and airborne flask measurement. NASA Langley Research Center is currently developing a triple-pulsed 2-micron Integrated Differential Absorption Lidar (IPDA) instrument for simultaneous measurement of water vapor and carbon-dioxide column density measurement from an air-borne platform. This presentation will give an overview of the 2 decades of 2-micron coherent and direction detection of laser/lidar development at NASA Langley Research Center and will present the ground and airborne wind and column CO2 measurement intercomparison with in-situ, balloon and flask measurements.

Double-Pulsed 2-Micrometer Lidar Validation for Atmospheric CO2 Measurements

NASA Technical Reports Server (NTRS)

Singh, Upendra N.; Refaat, Tamer F.; Yu, Jirong; Petros, Mulugeta; Remus, Ruben

2015-01-01

A double-pulsed, 2-micron Integrated Path Differential Absorption (IPDA) lidar instrument for atmospheric carbon dioxide (CO2) measurements is successfully developed at NASA Langley Research Center (LaRC). Based on direct detection technique, the instrument can be operated on ground or onboard a small aircraft. Key features of this compact, rugged and reliable IPDA lidar includes high transmitted laser energy, wavelength tuning, switching and locking, and sensitive detection. As a proof of concept, the IPDA ground and airborne CO2 measurement and validation will be presented. IPDA lidar CO2 measurements ground validation were conducted at NASA LaRC using hard targets and a calibrated in-situ sensor. Airborne validation, conducted onboard the NASA B-200 aircraft, included CO2 plum detection from power stations incinerators, comparison to in-flight CO2 in-situ sensor and comparison to air sampling at different altitude conducted by NOAA at the same site. Airborne measurements, spanning for 20 hours, were obtained from different target conditions. Ground targets included soil, vegetation, sand, snow and ocean. In addition, cloud slicing was examined over the ocean. These flight validations were conducted at different altitudes, up to 7 km, with different wavelength controlled weighing functions. CO2 measurement results agree with modeling conducted through the different sensors, as will be discussed.

Absorption degree analysis on biogas separation with ionic liquid systems.

PubMed

Zhang, Xin; Zhang, Suojiang; Bao, Di; Huang, Ying; Zhang, Xiangping

2015-01-01

For biogas upgrading, present work mainly focuses on either thermodynamics or mass transfer properties. A systematical study on these two aspects is important for developing a new biogas separation process. In this work, a new criterion "absorption degree", which combines both thermodynamics and mass transfer properties, was proposed for the first time to comprehensively evaluate the absorption performance. Henry's law constants of CO2 and CH4 in ionic liquids-polyethylene glycol dimethyl ethers mixtures were investigated. The liquid-side mass transfer coefficients (kL) were determined. The results indicate that IL-NHD mixtures exhibit not only a high CO2/CH4 selectivity, but also a fast kL for CO2 absorption. The [bmim][NO3]+NHD mixtures present a high absorption degree value for CO2 but a low value for CH4. For presenting a highest relative absorption degree value, the 50wt% [bmim][NO3]+50wt% NHD mixture is recommended for biogas upgrading. Copyright © 2014 Elsevier Ltd. All rights reserved.

Monitoring of catalyst performance in CO2 lasers using frequency modulation spectroscopy with diode lasers

NASA Technical Reports Server (NTRS)

Wang, Liang-Guo; Sachse, Glen

1990-01-01

Closed-cycle CO2 laser operation with removal of O2 and regeneration of CO2 can be achieved by catalytic CO-O2 recombination. Both parametric studies of the optimum catalyst formulation and long-term performance tests require on line monitoring of CO, O2 and CO2 concentrations. There are several existing methods for molecular oxygen detection. These methods are either intrusive (such as electrochemical method or mass spectrometry) or very expensive (such as CARS, UV laser absorption). Researchers demonstrated a high-sensitivity spectroscopic measurement of O2 using the two-tone frequency modulation spectroscopy (FMS) technique with a near infrared GaAlAs diode laser. Besides its inexpensive cost, fast response time, nonintrusive measurements and high sensitivity, this technique may also be used to differentiate between isotopes due to its high spectroscopic resolution. This frequency modulation spectroscopy technique could also be applied for the on-line monitoring of CO and CO2 using InGaAsP diode lasers operation in the 1.55 microns region and H2O in the 1.3 microns region. The existence of single mode optical fibers at the near infrared region makes it possible to combine FMS with optical fiber technology. Optical fiber FMS is particularly suitable for making point-measurements at one or more locations in the CO2 laser/catalyst system.

Synthesis and characterization of metastable, 20 nm-sized Pna21-LiCoPO4 nanospheres

NASA Astrophysics Data System (ADS)

Ludwig, Jennifer; Nordlund, Dennis; Doeff, Marca M.; Nilges, Tom

2017-04-01

The majority of research activities on LiCoPO4 are focused on the phospho-olivine (space group Pnma), which is a promising high-voltage cathode material for Li-ion batteries. In contrast, comparably little is known about its metastable Pna21 modification. Herein, we present a comprehensive study on the structure-property relationships of 15-20 nm Pna21-LiCoPO4 nanospheres prepared by a simple microwave-assisted solvothermal process. Unlike previous reports, the results indicate that the compound is non-stoichiometric and shows cation-mixing with Co ions on the Li sites, which provides an explanation for the poor electrochemical performance. Co L2,3-edge X-ray absorption spectroscopic data confirm the local tetrahedral symmetry of Co2+. Comprehensive studies on the thermal stability using thermogravimetric analysis, differential scanning calorimetry, and in situ powder X-ray diffraction show an exothermic phase transition to olivine Pnma-LiCoPO4 at 527 °C. The influence of the atmosphere and the particle size on the thermal stability is also investigated.

Effect of Feed Gas Flow Rate on CO2 Absorption through Super Hydrophobic Hollow Fiber membrane Contactor

NASA Astrophysics Data System (ADS)

Kartohardjono, Sutrasno; Alexander, Kevin; Larasati, Annisa; Sihombing, Ivander Christian

2018-03-01

Carbon dioxide is pollutant in natural gas that could reduce the heating value of the natural gas and cause problem in transportation due to corrosive to the pipeline. This study aims to evaluate the effects of feed gas flow rate on CO2 absorption through super hydrophobic hollow fiber contactor. Polyethyleneglycol-300 (PEG-300) solution was used as absorbent in this study, whilst the feed gas used in the experiment was a mixture of 30% CO2 and 70% CH4. There are three super hydrophobic hollow fiber contactors sized 6 cm and 25 cm in diameter and length used in this study, which consists of 1000, 3000 and 5000 fibers, respectively. The super hydrophobic fiber membrane used is polypropylene-based with outer and inner diameter of about 525 and 235 μm, respectively. In the experiments, the feed gas was sent through the shell side of the membrane contactor, whilst the absorbent solution was pumped through the lumen fibers. The experimental results showed that the mass transfer coefficient, flux, absorption efficiency for CO2-N2 system and CO2 loading increased with the feed gas flow rate, but the absorption efficiency for CO2-N2 system decreased. The mass transfer coefficient and the flux, at the same feed gas flow rate, decreased with the number of fibers in the membrane contactor, but the CO2 absorption efficiency and the CO2 loading increased.

CO 2 Absorption and Magnesium Carbonate Precipitation in MgCl 2–NH 3–NH 4Cl Solutions: Implications for Carbon Capture and Storage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Chen; Wang, Han; Li, Gen

CO 2 absorption and carbonate precipitation are the two core processes controlling the reaction rate and path of CO 2 mineral sequestration. Whereas previous studies have focused on testing reactive crystallization and precipitation kinetics, much less attention has been paid to absorption, the key process determining the removal efficiency of CO 2. In this study, adopting a novel wetted wall column reactor, we systematically explore the rates and mechanisms of carbon transformation from CO 2 gas to carbonates in MgCl 2–NH 3–NH 4Cl solutions. We find that reactive diffusion in liquid film of the wetted wall column is the rate-limitingmore » step of CO 2 absorption when proceeding chiefly through interactions between CO 2(aq) and NH 3(aq). We further quantified the reaction kinetic constant of the CO 2–NH 3 reaction. Our results indicate that higher initial concentration of NH 4Cl ( ≥2mol∙L -1) leads to the precipitation of roguinite [(NH 4) 2Mg(CO 3) 2∙4H 2O], while nesquehonite appears to be the dominant Mg-carbonate without NH 4Cl addition. We also noticed dypingite formation via phase transformation in hot water. This study provides new insight into the reaction kinetics of CO 2 mineral carbonation that indicates the potential of this technique for future application to industrial-scale CO 2 sequestration.« less

CO 2 Absorption and Magnesium Carbonate Precipitation in MgCl 2–NH 3–NH 4Cl Solutions: Implications for Carbon Capture and Storage

DOE PAGES

Zhu, Chen; Wang, Han; Li, Gen; ...

2017-09-19

CO 2 absorption and carbonate precipitation are the two core processes controlling the reaction rate and path of CO 2 mineral sequestration. Whereas previous studies have focused on testing reactive crystallization and precipitation kinetics, much less attention has been paid to absorption, the key process determining the removal efficiency of CO 2. In this study, adopting a novel wetted wall column reactor, we systematically explore the rates and mechanisms of carbon transformation from CO 2 gas to carbonates in MgCl 2–NH 3–NH 4Cl solutions. We find that reactive diffusion in liquid film of the wetted wall column is the rate-limitingmore » step of CO 2 absorption when proceeding chiefly through interactions between CO 2(aq) and NH 3(aq). We further quantified the reaction kinetic constant of the CO 2–NH 3 reaction. Our results indicate that higher initial concentration of NH 4Cl ( ≥2mol∙L -1) leads to the precipitation of roguinite [(NH 4) 2Mg(CO 3) 2∙4H 2O], while nesquehonite appears to be the dominant Mg-carbonate without NH 4Cl addition. We also noticed dypingite formation via phase transformation in hot water. This study provides new insight into the reaction kinetics of CO 2 mineral carbonation that indicates the potential of this technique for future application to industrial-scale CO 2 sequestration.« less

Lithologic mapping using Landsat thematic mapper data

USGS Publications Warehouse

Podwysocki, M.H.; Salisbury, J.W.; Jones, O.D.; Mimms, D.L.

1983-01-01

The Landsat-4 Thematic Mapper (TM), with its new near infrared bands centered at 1.65 μm and 2.20 μm and spatial resolution of 30 m has been used to distinguish rocks containing minerals having ferric-iron absorption bands in the visible and near-infrared and Al-O- and CO3 absorption bands in the 2.1-2.4 μm regions. On the basis of characteristic absorption bands, digitally processed TM data were used to differentiate vegetated from non-vegetated areas, limonitic from nonlimonitic rocks, rocks containing minerals having absorption bands in the near-infrared region from rocks lacking infrared absorption bands. Specific minerals were detected in both the humid eastern and semi-arid western United States. The absorption bands in the near-infrared region were used to detect kaolinite in open-pit exposures of a kaolin mining district near Macon, Georgia; calcium carbonate in the back sands along the east coast of Floridia; and kaolinite, alunite, jarosite, sericite and gypsum in natural exposures near Boulder City, Nevada. These results show that the additional spectral bands in the near-infrared region and increased spatial resolution of the Thematic Mapper provide a valuable tool for distinguishing several significant geologic materials not distinguishable from space using previous imaging systems. They also show that TM data can be successfully used in a variety of geologic environments.

HCO3− secretion and CaCO3 precipitation play major roles in intestinal water absorption in marine teleost fish in vivo

PubMed Central

Cooper, Christopher A.; Wilson, Rod W.

2010-01-01

The intestine of marine teleosts must effectively absorb fluid from ingested seawater to avoid dehydration. This fluid transport has been almost exclusively characterized as driven by NaCl absorption. However, an additional feature of the osmoregulatory role of the intestine is substantial net HCO3− secretion. This is suggested to drive additional fluid absorption directly (via Cl−/HCO3− exchange) and indirectly by precipitating ingested Ca2+ as CaCO3, thus creating the osmotic gradient for additional fluid absorption. The present study tested this hypothesis by perfusing the intestine of the European flounder in vivo with varying [Ca2+]: 10 (control), 40, and 90 mM. Fractional fluid absorption increased from 47% (control) to 73% (90 mM Ca2+), where almost all secreted HCO3− was excreted as CaCO3. This additional fluid absorption could not be explained by NaCl cotransport. Instead, a significant positive relationship between Na+-independent fluid absorption and total HCO3− secretion was consistent with the predicted roles for anion exchange and CaCO3 precipitation. Further analysis suggested that Na+-independent fluid absorption could be accounted for by net Cl− and H+ absorption (from Cl−/HCO3− exchange and CO2 hydration, respectively). There was no evidence to suggest that CaCO3 alone was responsible for driving fluid absorption. However, by preventing the accumulation of luminal Ca2+ it played a vital role by dynamically maintaining a favorable osmotic gradient all along the intestine, which permits substantially higher rates of solute-linked fluid absorption. To overcome the resulting hyperosmotic and highly acidic absorbate, it is proposed that plasma HCO3− buffers the absorbed H+ (from HCO3− production), and consequently reduces the osmolarity of the absorbed fluid entering the body. PMID:20130226

An ATR-FTIR Study on the Effect of Molecular Structural Variations on the CO2 Absorption Characteristics of Heterocyclic Amines, Part II

PubMed Central

Robinson, Kelly; McCluskey, Adam; Attalla, Moetaz I

2012-01-01

This paper reports on an ATR-FTIR spectroscopic investigation of the CO2 absorption characteristics of a series of heterocyclic diamines: hexahydropyrimidine (HHPY), 2-methyl and 2,2-dimethylhexahydropyrimidine (MHHPY and DMHHPY), hexahydropyridazine (HHPZ), piperazine (PZ) and 2,5- and 2,6-dimethylpiperazine (2,6-DMPZ and 2,5-DMPZ). By using in situ ATR-FTIR the structure–activity relationship of the reaction between heterocyclic diamines and CO2 is probed. PZ forms a hydrolysis-resistant carbamate derivative, while HHPY forms a more labile carbamate species with increased susceptibility to hydrolysis, particularly at higher CO2 loadings (>0.5 mol CO2/mol amine). HHPY exhibits similar reactivity toward CO2 to PZ, but with improved aqueous solubility. The α-methyl-substituted MHHPY favours HCO3− formation, but MHHPY exhibits comparable CO2 absorption capacity to conventional amines MEA and DEA. MHHPY show improved reactivity compared to the conventional α-methyl- substituted primary amine 2-amino-2-methyl-1-propanol. DMHHPY is representative of blended amine systems, and its reactivity highlights the advantages of such systems. HHPZ is relatively unreactive towards CO2. The CO2 absorption capacity CA (mol CO2/mol amine) and initial rates of absorption RIA (mol CO2/mol amine min−1) for each reactive diamine are determined: PZ: CA=0.92, RIA=0.045; 2,6-DMPZ: CA=0.86, RIA=0.025; 2,5-DMPZ: CA=0.88, RIA=0.018; HHPY: CA=0.85, RIA=0.032; MHHPY: CA=0.86, RIA=0.018; DMHHPY: CA=1.1, RIA=0.032; and HHPZ: no reaction. Calculations at the B3LYP/6-31+G** and MP2/6-31+G** calculations show that the substitution patterns of the heterocyclic diamines affect carbamate stability, which influences hydrolysis rates. PMID:22517608

Molten Salt Promoting Effect in Double Salt CO2 Absorbents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Keling; Li, Xiaohong S.; Chen, Haobo

2016-01-01

The purpose of this paper is to elaborate on the concept of molten salts as catalysts for CO2 absorption by MgO, and extend these observations to the MgO-containing double salt oxides. We will show that the phenomena involved with CO2 absorption by MgO and MgO-based double salts are similar and general, but with some important differences. This paper focuses on the following key concepts: i) identification of conditions that favor or disfavor participation of isolated MgO during double salt absorption, and investigation of methods to increase the absorption capacity of double salt systems by including MgO participation; ii) examination ofmore » the relationship between CO2 uptake and melting point of the promoter salt, leading to the recognition of the role of pre-melting (surface melting) in these systems; and iii) extension of the reaction pathway model developed for the MgO-NaNO3 system to the double salt systems. This information advances our understanding of MgO-based CO2 absorption systems for application with pre-combustion gas streams.« less

Kinetic analysis of an anion exchange absorbent for CO2 capture from ambient air.

PubMed

Shi, Xiaoyang; Li, Qibin; Wang, Tao; Lackner, Klaus S

2017-01-01

This study reports a preparation method of a new moisture swing sorbent for CO2 capture from air. The new sorbent components include ion exchange resin (IER) and polyvinyl chloride (PVC) as a binder. The IER can absorb CO2 when surrounding is dry and release CO2 when surrounding is wet. The manuscript presents the studies of membrane structure, kinetic model of absorption process, performance of desorption process and the diffusivity of water molecules in the CO2 absorbent. It has been proved that the kinetic performance of CO2 absorption/desorption can be improved by using thin binder and hot water treatment. The fast kinetics of P-100-90C absorbent is due to the thin PVC binder, and high diffusion rate of H2O molecules in the sample. The impressive is this new CO2 absorbent has the fastest CO2 absorption rate among all absorbents which have been reported by other up-to-date literatures.

Kinetic analysis of an anion exchange absorbent for CO2 capture from ambient air

PubMed Central

Shi, Xiaoyang; Li, Qibin; Lackner, Klaus S.

2017-01-01

This study reports a preparation method of a new moisture swing sorbent for CO2 capture from air. The new sorbent components include ion exchange resin (IER) and polyvinyl chloride (PVC) as a binder. The IER can absorb CO2 when surrounding is dry and release CO2 when surrounding is wet. The manuscript presents the studies of membrane structure, kinetic model of absorption process, performance of desorption process and the diffusivity of water molecules in the CO2 absorbent. It has been proved that the kinetic performance of CO2 absorption/desorption can be improved by using thin binder and hot water treatment. The fast kinetics of P-100-90C absorbent is due to the thin PVC binder, and high diffusion rate of H2O molecules in the sample. The impressive is this new CO2 absorbent has the fastest CO2 absorption rate among all absorbents which have been reported by other up-to-date literatures. PMID:28640914

Multi beam observations of cosmic radio noise using a VHF radar with beam forming by a Butler matrix

NASA Astrophysics Data System (ADS)

Renkwitz, T.; Singer, W.; Latteck, R.; Rapp, M.

2011-08-01

The Leibniz-Institute of Atmospheric Physics (IAP) in Kühlungsborn started to install a new MST radar on the North-Norwegian island Andøya (69.30° N, 16.04° E) in 2009. The new Middle Atmosphere Alomar Radar System (MAARSY) replaces the previous ALWIN radar which has been successfully operated for more than 10 years. The MAARSY radar provides increased temporal and spatial resolution combined with a flexible sequential point-to-point steering of the radar beam. To increase the spatiotemporal resolution of the observations a 16-port Butler matrix has been built and implemented to the radar. In conjunction with 64 Yagi antennas of the former ALWIN antenna array the Butler matrix simultaneously provides 16 individual beams. The beam forming capability of the Butler matrix arrangement has been verified observing the galactic cosmic radio noise of the supernova remnant Cassiopeia A. Furthermore, this multi beam configuration has been used in passive experiments to estimate the cosmic noise absorption at 53.5 MHz during events of enhanced solar and geomagnetic activity as indicators for enhanced ionization at altitudes below 90 km. These observations are well correlated with simultaneous observations of corresponding beams of the co-located imaging riometer AIRIS (69.14° N, 16.02° E) at 38.2 MHz. In addition, enhanced cosmic noise absorption goes along with enhanced electron densities at altitudes below about 90 km as observed with the co-located Saura MF radar using differential absorption and differential phase measurements.

Current 2-μm dial measurements of atmospheric CO2 and expected results from space using new MCT APDS

NASA Astrophysics Data System (ADS)

Dumas, A.; Gibert, F.; Rothman, J.; Édouart, D.; Le Mounier, F.; Cénac, C.

2017-11-01

In the framework of CO2 monitoring in the Atmospheric Boundary Layer (ABL), a ground-based 2-μm Differential Absorption Lidar (DIAL) has been developed at the Laboratoire de Météorologie Dynamique (LMD) in Palaiseau. In order to derive flux information, this system has been set up with coherent detection, which allows to combine CO2 density measurements with wind velocity measurements. On the other hand, new advances in the field of Mercury Cadmium Tellure (MCT) Avalanche Photodiodes (APDs) open the way for high-precision measurements in direct detection ultimately from space. In this study, we first report on state of the art measurements obtained with the current coherent DIAL system before presenting expected results for a similar laser transmitter equipped with MCT APDs. For this latter part, we use a numerical model which relies on APDs performance data provided by the Laboratoire d'Électronique et de Technologie de l'Information (LETI).

Bond-selective imaging of deep tissue through the optical window between 1600 and 1850 nm.

PubMed

Wang, Pu; Wang, Han-Wei; Sturek, Michael; Cheng, Ji-Xin

2012-01-01

We report the employment of an optical window between 1600 nm and 1850 nm for bond-selective deep tissue imaging through harmonic vibrational excitation and acoustic detection of resultant pressure waves. In this window where a local minimum of water absorption resides, we found a 5 times enhancement of photoacoustic signal by first overtone excitation of the methylene group CH(2) at 1730 nm, compared to the second overtone excitation at 1210 nm. The enhancement allows 3D mapping of intramuscular fat with improved contrast and of lipid deposition inside an atherosclerotic artery wall in the presence of blood. Moreover, lipid and protein are differentiated based on the first overtone absorption profiles of CH(2) and methyl group CH(3) in this window. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Research on atmospheric CO2 remote sensing with open-path tunable diode laser absorption spectroscopy and comparison methods

NASA Astrophysics Data System (ADS)

Xin, Fengxin; Guo, Jinjia; Sun, Jiayun; Li, Jie; Zhao, Chaofang; Liu, Zhishen

2017-06-01

An open-path atmospheric CO2 measurement system was built based on tunable diode laser absorption spectroscopy (TDLAS). The CO2 absorption line near 2 μm was selected, measuring the atmospheric CO2 with direct absorption spectroscopy and carrying on the comparative experiment with multipoint measuring instruments of the open-path. The detection limit of the TDLAS system is 1.94×10-6. The calibration experiment of three AZ-7752 handheld CO2 measuring instruments was carried out with the Los Gatos Research gas analyzer. The consistency of the results was good, and the handheld instrument could be used in the TDLAS system after numerical calibration. With the contrast of three AZ-7752 and their averages, the correlation coefficients are 0.8828, 0.9004, 0.9079, and 0.9393 respectively, which shows that the open-path TDLAS has the best correlation with the average of three AZ-7752 and measures the concentration of atmospheric CO2 accurately. Multipoint measurement provides a convenient comparative method for open-path TDLAS.

Regeneration of 2-amino-2-methyl-1-propanol used for carbon dioxide absorption.

PubMed

Zhang, Pei; Shi, Yao; Wei, Jianwen; Zhao, Wei; Ye, Qing

2008-01-01

To improve the efficiency of the carbon dioxide cycling process and to reduce the regeneration energy consumption, a sterically hindered amine of 2-amino-2-methyl-1-propranol (AMP) was investigated to determine its regeneration behavior as a CO2 absorbent. The CO2 absorption and amine regeneration characteristics were experimentally examined under various operating conditions. The regeneration efficiency increased from 86.2% to 98.3% during the temperature range of 358 to 403 K. The most suitable regeneration temperature for AMP was 383 K, in this experiment condition, and the regeneration efficiency of absorption/regenerationruns descended from 98.3% to 94.0%. A number of heat-stable salts (HSS) could cause a reduction in CO2 absorption capacity and regeneration efficiency. The results indicated that aqueous AMP was easier to regenerate with less loss of absorption capacity than other amines, such as, monoethanolamine (MEA), diethanolamine (DEA), diethylenetriamine (DETA), and N-methyldiethanolamine (MDEA).

An overview of NASA's ASCENDS Mission's Lidar Measurement Requirements

NASA Astrophysics Data System (ADS)

Abshire, J. B.; Browell, E. V.; Menzies, R. T.; Lin, B.; Spiers, G. D.; Ismail, S.

2014-12-01

The objectives of NASA's ASCENDS mission are to improve the knowledge of global CO2 sources and sinks by precisely measuring the tropospheric column abundance of atmospheric CO2 and O2. The mission will use a continuously operating nadir-pointed integrated path differential absorption (IPDA) lidar in a polar orbit. The lidar offers a number of important new capabilities and will measure atmospheric CO2 globally over a wide range of challenging conditions, including at night, at high latitudes, through hazy and thin cloud conditions, and to cloud tops. The laser source enables a measurement of range, so that the absorption path length to the scattering surface will be always accurately known. The lidar approach also measures consistently in a nadir-zenith path and the narrow laser linewidth allows weighting the measurement to the lower troposphere. Using these measurements with atmospheric and flux models will allow improved estimates of CO2 fluxes and hence better understanding of the processes that exchange CO2 between the surface and atmosphere. The ASCENDS formulation team has developed a preliminary set of requirements for the lidar measurements. These were developed based on experience gained from the numerous ASCENDS airborne campaigns that have used different candidate lidar measurement techniques. They also take into account the complexity of making precise measurement of atmospheric gas columns when viewing the Earth from space. Some of the complicating factors are the widely varying reflectance and topographic heights of the Earth's land and ocean surfaces, the variety of cloud types, and the degree of cloud and aerosol absorption and scattering in the atmosphere. The requirements address the precision and bias in the measured column mixing ratio, the dynamic range of the expected surface reflected signal, the along-track sampling resolution, measurements made through thin clouds, measurements to forested and slope surfaces, range precision, measurements to cloud tops, knowledge of the laser spot position, and off-nadir pointing. These requirements are independent of the measurement approach, and are consistent with the initial mission simulation studies performed by the formulation team. This presentation will summarize the requirements along with examples that have guided their selection.

Measurement of diffusion coefficients important in modeling the absorption rate of carbon dioxide into aqueous N-methyldiethanolamine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rowley, R.L.; Adams, M.E.; Marshall, T.L.

1997-03-01

Natural gas processors use amine treating processes to remove the acid gases H{sub 2}S and CO{sub 2} from gas streams. Absorption rates of gaseous CO{sub 2} into aqueous N-methyldiethanolamine (MDEA) solutions were measured in a quiescent, inverted-tube diffusiometer by monitoring the rate of pressure drop. The absorption rate was found to be insensitive to the diffusion coefficient of CO{sub 2} in solution but very sensitive to the diffusion rate of bicarbonate and protonated MDEA ions. Evidence also suggested that chemical reaction equilibrium is rapid relative to diffusion. A numerical model was developed on the basis of these observations. The modelmore » was used to regress diffusion coefficients of bicarbonate and protonated amine, which must be equivalent by electroneutrality arguments, from measured absorption rates. Complete modeling of the absorption process also required data for the diffusion coefficient of MDEA in water. These were measured using a Taylor dispersion apparatus. CO{sub 2} absorption rates and diffusion coefficients of bicarbonate and protonated MDEA were obtained at 298.2 K and 318.2 K in solutions containing 20, 35, and 50 mass % MDEA in water.« less

Airborne Lidar measurements of Atmospheric CO2 Column Absorption and Line Shapes from 3-11 km altitudes

NASA Astrophysics Data System (ADS)

Abshire, J. B.; Riris, H.; Allan, G. R.; Weaver, C.; Mao, J.; Hasselbrack, W.

2009-04-01

Accurate measurements of tropospheric CO2 abundances with global-coverage are needed to quantify processes that regulate CO2 exchange with the land and oceans. The 2007 Decadal Survey for Earth Science by the US National Research Council recommended a space-based CO2 measuring mission called ASCENDS. We have been developing a technique for the remote measurement of tropospheric CO2 concentrations from aircraft and as a candidate for the ASCENDS mission. It uses the 1570-nm CO2 band and a dual channel laser absorption spectrometer (ie DIAL used in altimeter mode). It uses several tunable laser transmitters allowing simultaneous measurement of the absorption from a CO2 absorption line in the 1570 nm band, O2 extinction in the oxygen A-band, and surface height and aerosol backscatter in the same path. It directs the narrow co-aligned laser beams toward nadir, and measures the energy of the laser echoes reflected from land and water surfaces. During the measurement, the lasers are stepped in wavelength across the CO2 line and an O2 line (near 765 nm) at a ~ 1 kHz rate. The receiver uses a telescope and photon counting detectors, and measures the background light and energies of the laser echoes from the surface along with scattering from any aerosols in the path. The gas extinction and column densities for the CO2 and O2 gases are estimated from the ratio of the on- and off- line signals via the DIAL technique. We use pulsed laser signals and time gating to isolate the laser echo signals from the surface, and to reject photons scattered from thin clouds and aerosols in the path. Previously we had constructed breadboard versions of our CO2 and O2 sensors, using tunable diode lasers, fiber laser amplifiers and 20 cm diameter telescopes. We have used them to make measurements of gas absorptions over 0.2, 0.4 and 1.3 km long outdoor paths. We also have also calculated several characteristics of the technique for space and have performed an initial space mission accommodation study. During 2008 we reconfigured our lidar for airborne use and made measurements of atmospheric CO2 absorption in the nadir column from the aircraft to the surface during 5 flights. The airborne lidar sweeps the laser wavelength across the CO2 line in either 10 or 20 steps per measurement. The line scan rate is ~ 1 KHz and the laser pulse widths are 1 usec. The time resolved laser backscatter is collected by the telescope and detected by a photomultiplier and recorded by a photon counting timing system. We installed our lidar on the NASA Glenn Lear-25 aircraft in October and first made measurements using the 1571.4 nm CO2 absorption line while flying in northern Ohio. We made laser backscatter and absorption measurements over a variety of land surface types, water surfaces and through thin clouds, broken clouds and to cloud tops. Strong laser signals were observed at altitudes from 2.5 to 11 km on two flights. We completed three additional flights during December 2008 and gathered over 6 hours of atmospheric CO2 column measurements using the 1572.02 and 1572.33 nm CO2 lines. Airborne CO2 line shape and absorption measurements were made while flying at 3-11 km altitudes over southwestern Ohio. Subsequently two flights were made from Ponca City OK, just east of the US Department of Energy's (DOE) ARM site. We made 4 hours of airborne measurements in square patterns around the ARM site at altitudes from 3-8 km. The increased CO2 line absorptions at higher altitudes were evident in all flights. The December flights were also coordinated with DOE investigators who flew an in-situ CO2 sensor on a Cessna aircraft inside the CO2 sounder's flight pattern. These yielded two height resolved profiles of CO2 concentrations from 5 km to the surface, which are being analyzed with radiosonde measurements for comparisons. More details of the flights, measurements and their analysis will be described in the presentation.

Effect of Co doping concentration on structural properties and optical parameters of Co-doped ZnO thin films by sol-gel dip-coating method.

PubMed

Nam, Giwoong; Yoon, Hyunsik; Kim, Byunggu; Lee, Dong-Yul; Kim, Jong Su; Leem, Jae-Young

2014-11-01

The structural and optical properties of Co-doped ZnO thin films prepared by a sol-gel dip-coating method were investigated. X-ray diffraction analysis showed that the thin films were grown with a c-axis preferred orientation. The position of the (002) peak was almost the same in all samples, irrespective of the Co concentration. It is thus clear that Co doping had little effect on the position of the (002) peak. To confirm that Co2+ was substituted for Zn2+ in the wurtzite structure, optical measurements were conducted at room temperature by a UV-visible spectrometer. Three absorption peaks are apparent in the Co-doped ZnO thin films that do not appear for the undoped ZnO thin film. As the Co concentration was increased, absorption related to characteristic Co2+ transitions increased because three absorption band intensities and the area underneath the absorption wells between 500 and 700 nm increased with increasing Co concentration. The optical band gap and static dielectric constant decreased and the Urbach energy and extinction coefficient increased with increasing Co concentration.

Assessment of MFLL column CO2 measurements obtained during the ACT-America field campaigns

NASA Astrophysics Data System (ADS)

Lin, B.; Browell, E. V.; Kooi, S. A.; Dobler, J. T.; Campbell, J.; Fan, T. F.; Pal, S.; O'Dell, C. W.; Obland, M. D.; Erxleben, W. H.; McGregor, D.; Kochanov, R. V.; DiGangi, J. P.; Davis, K. J.; Choi, Y.

2017-12-01

Accurate observations of atmospheric CO2 with airborne and space-based lidar systems such as those used during the Atmospheric Carbon and Transport - America (ACT-America) field campaigns and proposed for the NASA ASCENDS mission would improve our knowledge of CO2 distributions and variations on both regional and global scales, reduce the uncertainties in atmospheric CO2 transport and fluxes, and increase confidence in predictions of future climate changes. To reach these scientific goals, atmospheric column CO2 (XCO2) measurements of the Harris Corporation's Multifunctional Fiber Laser Lidar (MFLL) obtained during the first two ACT-America flight campaigns have been thoroughly investigated by the ACT-America lidar measurement group. MFLL is an intensity-modulated continuous-wave lidar operating in the 1.57-mm CO2 absorption band. Atmospheric XCO2 amounts are retrieved based on the integrated path differential absorption of the lidar signals at online and offline wavelengths between the aircraft and the ground. NASA Langley Research Center and Harris have been collaborating in the development and evaluation of this CO2 lidar approach for a number of years. To gain insights into the lidar performance, the measurement group has collected all possible lidar measurements with corresponding in-situ atmospheric profile information from the first two ACT-America field campaigns, including the data from several flight legs dedicated to lidar calibration. Initially large differences (-1 to 2 %) were found between lidar measured CO2 optical depths and those derived from in-situ observations and spectroscopy from HITRAN2008. When an improved spectroscopic model (Pre-HITRAN2016) was applied, the large systematic errors were much more consistent leading to the development of an empirical linear correction of measured optical depth based on the calibration flight data. This correction accounts for remaining uncertainties in spectroscopic models, environmental conditions, such as temperature, pressure, and water vapor, and possible instrumental issues like optical cross-talk between wavelengths introduced in the power amplifier. Results from a flight of Gulf of Mexico with a very homogenous environment showed that the precision of lidar XCO2 measurements was as high as about 0.5ppm for 10-s averages.

CO AND H{sub 2} ABSORPTION IN THE AA TAURI CIRCUMSTELLAR DISK

DOE Office of Scientific and Technical Information (OSTI.GOV)

France, Kevin; Burgh, Eric B.; Schindhelm, Eric

2012-01-01

The direct study of molecular gas in inner protoplanetary disks is complicated by uncertainties in the spatial distribution of the gas, the time variability of the source, and the comparison of observations across a wide range of wavelengths. Some of these challenges can be mitigated with far-ultraviolet spectroscopy. Using new observations obtained with the Hubble Space Telescope Cosmic Origins Spectrograph, we measure column densities and rovibrational temperatures for CO and H{sub 2} observed on the line of sight through the AA Tauri circumstellar disk. CO A - X absorption bands are observed against the far-UV continuum. The CO absorption ismore » characterized by log{sub 10}(N({sup 12}CO)) = 17.5 {+-} 0.5 cm{sup -2} and T{sub rot}(CO) = 500{sup +500}{sub -200} K, although this rotational temperature may underestimate the local kinetic temperature of the CO-bearing gas. We also detect {sup 13}CO in absorption with an isotopic ratio of {approx}20. We do not observe H{sub 2} absorption against the continuum; however, hot H{sub 2} (v > 0) is detected in absorption against the Ly{alpha} emission line. We measure the column densities in eight individual rovibrational states, determining a total log{sub 10}(N(H{sub 2})) = 17.9{sup +0.6}{sub -0.3} cm{sup -2} with a thermal temperature of T(H{sub 2}) = 2500{sup +800}{sub -700} K. The high temperature of the molecules, the relatively small H{sub 2} column density, and the high inclination of the AA Tauri disk suggest that the absorbing gas resides in an inner disk atmosphere. If the H{sub 2} and CO are cospatial within a molecular layer {approx}0.6 AU thick, this region is characterized by {approx} 10{sup 5} cm{sup -3} with an observed (CO/H{sub 2}) ratio of {approx}0.4. We also find evidence for a departure from a purely thermal H{sub 2} distribution, suggesting that excitation by continuum photons and H{sub 2} formation may be altering the level populations in the molecular gas.« less

High resolution x-ray absorption and emission spectroscopy of Li x CoO2 single crystals as a function delithiation

NASA Astrophysics Data System (ADS)

Simonelli, L.; Paris, E.; Iwai, C.; Miyoshi, K.; Takeuchi, J.; Mizokawa, T.; Saini, N. L.

2017-03-01

The effect of delithiation in Li x CoO2 is studied by high resolution Co K-edge x-ray absorption and x-ray emission spectroscopy. Polarization dependence of the x-ray absorption spectra on single crystal samples is exploited to reveal information on the anisotropic electronic structure. We find that the electronic structure of Li x CoO2 is significantly affected by delithiation in which the Co ions oxidation state tending to change from 3+  to 4+. The Co intersite (intrasite) 4p-3d hybridization suffers a decrease (increase) by delithiation. The unoccupied 3d t 2g orbitals with a 1g symmetry, containing substantial O 2p character, hybridize isotropically with Co 4p orbitals and likely to have itinerant character unlike anisotropically hybridized 3d e g orbitals. Such a peculiar electronic structure could have significant effect on the mobility of Li in Li x CoO2 cathode and hence the battery characteristics.

Enhanced stability and chemical resistance of a new nanoscale biocatalyst for accelerating CO2 absorption into a carbonate solution.

PubMed

Zhang, Shihan; Lu, Hong; Lu, Yongqi

2013-12-03

A novel potassium-carbonate-based absorption process is currently being developed to reduce the energy consumption when capturing CO2 from coal combustion flue gas. The process employs the enzyme carbonic anhydrase (CA) as a catalyst to accelerate the rate of CO2 absorption. This study focused on the immobilization of a new variant of the CA enzyme onto a new group of nonporous nanoparticles to improve the enzyme's thermal stability and its chemical resistance to major impurities from the flue gas. The CA enzyme was manufactured at the pilot scale by a leading enzyme company. As carrier materials, two different batches of SiO2-ZrO2 composite nanoparticles and one batch of silica nanoparticle were synthesized using a flame spray pyrolysis method. Classic Danckwerts absorption theory with reaction was applied to determine the kinetics of the immobilized enzymes for CO2 absorption. The immobilized enzymes retained 56-88% of their original activity in a K2CO3/KHCO3 solution over a 60-day test period at 50 °C, compared with a 30% activity retention for their free CA enzyme counterpart. The immobilized CA enzymes also revealed improved chemical stability. The inactivation kinetics of the free and immobilized CA enzymes in the K2CO3/KHCO3 solution were experimentally quantified.

Co7Fe3 and Co7Fe3@SiO2 Nanospheres with Tunable Diameters for High-Performance Electromagnetic Wave Absorption.

PubMed

Chen, Na; Jiang, Jian-Tang; Xu, Cheng-Yan; Yuan, Yong; Gong, Yuan-Xun; Zhen, Liang

2017-07-05

Ferromagnetic metal/alloy nanoparticles have attracted extensive interest for electromagnetic wave-absorbing applications. However, ferromagnetic nanoparticles are prone to oxidization and producing eddy currents, leading to the deterioration of electromagnetic properties. In this work, a simple and scalable liquid-phase reduction method was employed to synthesize uniform Co 7 Fe 3 nanospheres with diameters ranging from 350 to 650 nm for high-performance microwave absorption application. Co 7 Fe 3 @SiO 2 core-shell nanospheres with SiO 2 shell thicknesses of 30 nm were then fabricated via a modified Stöber method. When tested as microwave absorbers, bare Co 7 Fe 3 nanospheres with a diameter of 350 nm have a maximum reflection loss (RL) of 78.4 dB and an effective absorption with RL > 10 dB from 10 to 16.7 GHz at a small thickness of 1.59 mm. Co 7 Fe 3 @SiO 2 nanospheres showed a significantly enhanced microwave absorption capability for an effective absorption bandwidth and a shift toward a lower frequency, which is ascribed to the protection of the SiO 2 shell from direct contact among Co 7 Fe 3 nanospheres, as well as improved crystallinity and decreased defects upon annealing. This work illustrates a simple and effective method to fabricate Co 7 Fe 3 and Co 7 Fe 3 @SiO 2 nanospheres as promising microwave absorbers, and the design concept can also be extended to other ferromagnetic alloy particles.

Quantitative phase-filtered wavelength-modulated differential photoacoustic radar tumor hypoxia imaging toward early cancer detection.

PubMed

Dovlo, Edem; Lashkari, Bahman; Soo Sean Choi, Sung; Mandelis, Andreas; Shi, Wei; Liu, Fei-Fei

2017-09-01

Overcoming the limitations of conventional linear spectroscopy used in multispectral photoacoustic imaging, wherein a linear relationship is assumed between the absorbed optical energy and the absorption spectra of the chromophore at a specific location, is crucial for obtaining accurate spatially-resolved quantitative functional information by exploiting known chromophore-specific spectral characteristics. This study introduces a non-invasive phase-filtered differential photoacoustic technique, wavelength-modulated differential photoacoustic radar (WM-DPAR) imaging that addresses this issue by eliminating the effect of the unknown wavelength-dependent fluence. It employs two laser wavelengths modulated out-of-phase to significantly suppress background absorption while amplifying the difference between the two photoacoustic signals. This facilitates pre-malignant tumor identification and hypoxia monitoring, as minute changes in total hemoglobin concentration and hemoglobin oxygenation are detectable. The system can be tuned for specific applications such as cancer screening and SO 2 quantification by regulating the amplitude ratio and phase shift of the signal. The WM-DPAR imaging of a head and neck carcinoma tumor grown in the thigh of a nude rat demonstrates the functional PA imaging of small animals in vivo. The PA appearance of the tumor in relation to tumor vascularity is investigated by immunohistochemistry. Phase-filtered WM-DPAR imaging is also illustrated, maximizing quantitative SO 2 imaging fidelity of tissues. Oxygenation levels within a tumor grown in the thigh of a nude rat using the two-wavelength phase-filtered differential PAR method. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Spectroscopic, and thermal studies of some new binuclear transition metal(II) complexes with hydrazone ligands containing acetoacetanilide and isoxazole.

PubMed

Chen, Zhimin; Wu, Yiqun; Gu, Donghong; Gan, Fuxi

2007-11-01

A new chelating ligand, 2-(2-(5-tert-butylisoxazol-3-yl)hydrazono)-N-(2,4-dimethylphenyl)-3-oxobutanamide (HL), and its four binuclear transition metal complexes, M(2)(L)(2) (micro-OCH(3))(2) [M=Ni(II), Co(II), Cu(II), Zn(II)], were synthesized using the procedure of diazotization, coupling and metallization. Their structures were postulated based on elemental analysis, (1)H NMR, MALDI-MS, FT-IR spectra and UV-vis electronic absorption spectra. Smooth films of these complexes on K9 glass substrates were prepared using the spin-coating method and their absorption properties were evaluated. The thermal properties of the metal(II) complexes were investigated by thermogravimetry (TG) and differential scanning calorimetry (DSC). Different thermodynamic and kinetic parameters namely activation energy (E*), enthalpy of activation (DeltaH*), entropy of activation (DeltaS*) and free energy change of activation (DeltaG*) are calculated using Coats-Redfern (CR) equation.

Proximal bicarbonate absorption independent of Na+-H+ exchange: effect of bicarbonate load.

PubMed

Bank, N; Aynedjian, H S; Mutz, B F

1989-04-01

To study proximal tubule bicarbonate absorption that is not due to the neutral Na+-H+ antiporter, mid to late proximal convolutions of the rat kidney were microperfused in vivo with a sodium-free choline solution containing 10(-3) M amiloride. The average sodium concentration resulting from sodium influx was 12 mM. At such low intraluminal [Na+], 10(-3) M amiloride should have inhibited the Na+-H+ antiporter by greater than 95%. When 25 mM HCO3- was in the perfusion fluid, measured total CO2 absorption was 100 pmol.mm-1.min-1. When luminal [HCO3-] was raised to 50 mM, and blood [HCO3-] was also raised to approximately 50 mM to avoid a transepithelial HCO3- concentration gradient, total CO2 absorption increased to greater than 300 pmol.mm-1.min-1. Thus raising intraluminal HCO3- concentration caused a marked increase in total CO2 absorption even though intraluminal [Na+] was low and amiloride was present. Control perfusions containing 140 mM Na+ yielded total CO2 absorption that was approximately 100 pmol.mm-1.min-1 higher than with the respective sodium-free perfusion solutions. In additional experiments, either DCCD or NEM was added to sodium-free perfusion solutions to inhibit H+-ATPase. These inhibitors reduced Na+-H+ independent total CO2 absorption markedly. Our observations suggest that under physiological acid-base conditions, sodium-independent H+ secretion can account for approximately 50% of total HCO3- absorption in mid to late proximal convolutions. This mechanism is stimulated by an increase in ambient HCO(-3) concentration to a degree that might account for the load-dependency of proximal HCO(-3) absorption in these segments of the proximal tubule.(ABSTRACT TRUNCATED AT 250 WORDS)

Molten salt CO2 capture and electro-transformation (MSCC-ET) into capacitive carbon at medium temperature: effect of the electrolyte composition.

PubMed

Deng, Bowen; Chen, Zhigang; Gao, Muxing; Song, Yuqiao; Zheng, Kaiyuan; Tang, Juanjuan; Xiao, Wei; Mao, Xuhui; Wang, Dihua

2016-08-15

Electrochemical transformation of CO2 into functional materials or fuels (i.e., carbon, CO) in high temperature molten salts has been demonstrated as a promising way of carbon capture, utilisation and storage (CCUS) in recent years. In a view of continuous operation, the electrolysis process should match very well with the CO2 absorption kinetics. At the same time, in consideration of the energy efficiency, a molten salt electrochemical cell running at lower temperature is more beneficial to a process powered by the fluctuating renewable electricity from solar/wind farms. Ternary carbonates (Li : Na : K = 43.5 : 31.5 : 25.0) and binary chlorides (Li : K = 58.5 : 41.5), two typical kinds of eutectic melt with low melting points and a wide electrochemical potential window, could be the ideal supporting electrolyte for the molten salt CO2 capture and electro-transformation (MSCC-ET) process. In this work, the CO2 absorption behaviour in Li2O/CaO containing carbonates and chlorides were investigated on a home-made gas absorption testing system. The electrode processes as well as the morphology and properties of carbon obtained in different salts are compared to each other. It was found that the composition of molten salts significantly affects the absorption of CO2, electrode processes and performance of the product. Furthermore, the relationship between the absorption and electro-transformation kinetics are discussed based on the findings.

The effects of colorimetric detection of heavy metal ions based on Au nanoparticles (NPs): size and shape—a case of Co2+

NASA Astrophysics Data System (ADS)

Leng, Yumin; He, Junbao; Li, Bo; Xing, Xiaojing; Guo, Yongming; Ye, Liqun; Lu, Zhiwen

2017-09-01

The different sized and shaped Au NPs have intrigued considerable attention, because they possess different surface plasma resonance (SPR) absorption bands and thus result in many colorimetric Au NP-based detection applications. In this article, four different sized and shaped Au NPs of nanodots/rods were prepared and characterized. The as-prepared Au NPs were modified by the negatively charged anions of [SCH2CO2]2- to investigate both the size and shape effects of modified Au NPs on colorimetric detection of Co2+ and the corresponding SPR absorption properties. The different-shaped Au NPs possess different SPR absorption properties. The Au nanorods appeared to be colorimetric sensitive for Co2+ sensing.

Heterogeneous and Evolving Distributions of Pluto's Volatile Surface Ices

NASA Astrophysics Data System (ADS)

Grundy, William M.; Olkin, C. B.; Young, L. A.; Buie, M. W.; Young, E. F.

2013-10-01

We report observations of Pluto's 0.8 to 2.4 µm reflectance spectrum with IRTF/SpeX on 70 nights over the 13 years from 2001 to 2013. The spectra show numerous vibrational absorption features of simple molecules CH4, CO, and N2 condensed as ices on Pluto's surface. These absorptions are modulated by the planet's 6.39 day rotation period, enabling us to constrain the longitudinal distributions of the three ices. Absorptions of CO and N2 are concentrated on Pluto's anti-Charon hemisphere, unlike absorptions of less volatile CH4 ice that are offset by roughly 90° from the longitude of maximum CO and N2 absorption. In addition to the diurnal/longitudinal variations, the spectra show longer term trends. On decadal timescales, Pluto's stronger CH4 absorption bands have deepened, while the amplitude of their diurnal variation has diminished, consistent with additional CH4 absorption by high northern latitude regions rotating into view as the sub-Earth latitude moves north (as defined by the system's angular momentum vector). Unlike the CH4 absorptions, Pluto's CO and N2 absorptions are declining over time, suggesting more equatorial or southerly distributions of those species. The authors gratefully thank the staff of IRTF for their tremendous assistance over the dozen+ years of this project. The work was funded in part by NSF grants AST-0407214 and AST-0085614 and NASA grants NAG5-4210 and NAG5-12516.

Measuring Nitrous Oxide Mass Transfer into Non-Aqueous CO2BOL CO2 Capture Solvents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Whyatt, Greg A.; Freeman, Charles J.; Zwoster, Andy

2016-03-28

This paper investigates CO2 absorption behavior in CO2BOL solvents by decoupling the physical and chemical effects using N2O as a non-reactive mimic. Absorption measurements were performed using a wetted-wall contactor. Testing was performed using a “first generation” CO2 binding organic liquid (CO2BOL), comprised of an independent base and alcohol. Measurements were made with N2O at a lean (0.06 mol CO2/mol BOL) and rich (0.26 mol CO2/mol BOL) loading, each at three temperatures (35, 45 and 55 °C). Liquid-film mass transfer coefficients (kg') were calculated by subtracting the gas film resistance – determined from a correlation from literature – from themore » overall mass transfer measurement. The resulting kg' values for N2O in CO2BOLs were found to be higher than that of 5 M aqueous MEA under comparable conditions, which is supported by published measurements of Henry’s coefficients for N2O in various solvents. These results suggest that the physical solubility contribution for CO2 absorption in CO2BOLs is greater than that of aqueous amines, an effect that may pertain to other non-aqueous solvents.« less

CO{sub 2}-philic oligomers as novel solvents for CO{sub 2} absorption

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, Matthew B; Luebke, David R; Enick, Robert M

2010-01-01

Desirable properties for an oligomeric CO{sub 2}-capture solvent in an integrated gasification combined cycle (IGCC) plant include high selectivity for CO{sub 2} over H{sub 2} and water, low viscosity, low vapor pressure, low cost, and minimal environmental, health, and safety impacts. The neat solvent viscosity and solubility of CO{sub 2}, measured via bubble-point loci and presented on a pressure−composition diagram (weight basis), and water miscibility in CO{sub 2}-philic solvents have been determined and compared to results obtained with Selexol, a commercial oligomeric CO{sub 2} solvent. The solvents tested include polyethyleneglycol dimethylether (PEGDME), polypropyleneglycol dimethylether (PPGDME), polypropyleneglycol diacetate (PPGDAc), polybutyleneglycol diacetatemore » (PBGDAc), polytetramethyleneetherglycol diacetate (PTMEGDAc), glyceryl triacetate (GTA), polydimethyl siloxane (PDMS), and perfluorpolyether (PFPE) that has a perfluorinated propyleneglycol monomer unit. Overall, PDMS and PPGDME are the best oligomeric solvents tested and exhibit properties that make them very promising alternatives for the selective absorption of CO{sub 2} from a mixed gas stream, especially if the absorption of water is undesirable.« less

2-micron Pulsed Direct Detection IPDA Lidar for Atmospheric CO2 Measurements

NASA Astrophysics Data System (ADS)

Yu, J.; Singh, U.; Petros, M.

2012-12-01

A 2-micron high energy, pulsed Integrated Path Differential Absorption (IPDA) lidar is being developed for atmospheric CO2 measurements. Development of this lidar heavily leverages the 2-micron laser technologies developed in LaRC over the last decade. The high pulse energy, direct detection lidar operating at CO2 2-micron absorption band provides an alternate approach to measure CO2 concentrations with significant advantages. It is expected to provide high-precision measurement capability by unambiguously eliminating contamination from aerosols and clouds that can bias the IPDA measurement. Our objective is to integrate an existing high energy double-pulsed 2-micron laser transmitter with a direct detection receiver and telescope to enable an airborne capability to perform a first proof of principle demonstration of airborne direct detection CO2 measurements. The 2-micron transmitter provides 100mJ at 10Hz with double pulse format specifically designed for DIAL/IPDA instrument. The compact, rugged, highly reliable transceiver is based on unique Ho:Tm:YLF high-energy 2-micron pulsed laser technology. All the optical mounts are custom designed and have space heritage. A 16-inch diameter telescope has been designed and being manufactured for the direct detection lidar. The detector is an InGaAs Positive-Intrinsic-Negative (PIN) photodiode manufactured by Hamamatsu Corporation. The performance of the detector is characterized at various operating temperatures and bias voltages for spectral response, NEP, response time, dynamic range, and linearity. A collinear lidar structure is designed to be integrated to NASA UC12 or B200 research aircrafts. This paper will describe the design of the airborne 2-micron pulsed IPDA lidar system; the lidar operation parameters; the wavelength pair selection; laser transmitter energy, pulse rate, beam divergence, double pulse generation and accurate frequency control; detector characterization; telescope design; lidar structure design; and lidar signal to noise ratio estimation. The first engineering flight is scheduled at the end of next year.

Measuring the Absorption Rate of CO 2 in Nonaqueous CO 2 -Binding Organic Liquid Solvents with a Wetted-Wall Apparatus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mathias, Paul M.; Zheng, Feng; Heldebrant, David J.

2015-09-17

The kinetics of the absorption of CO 2 into two nonaqueous CO 2-binding organic liquid (CO 2BOL) solvents were measured at T=35, 45, and 55 °C with a wetted-wall column. Selected CO 2 loadings were run with a so-called “first-generation” CO 2BOL, comprising an independent base and alcohol, and a “second-generation” CO 2BOL, in which the base and alcohol were conjoined. Liquid-film mass-transfer coefficient (k'g) values for both solvents were measured to be comparable to values for monoethanolamine and piperazine aqueous solvents under a comparable driving force, in spite of far higher solution viscosities. An inverse temperature dependence of themore » k'g value was also observed, which suggests that the physical solubility of CO 2 in organic liquids may be making CO 2 mass transfer faster than expected. Aspen Plus software was used to model the kinetic data and compare the CO 2 absorption behavior of nonaqueous solvents with that of aqueous solvent platforms. This work continues our development of the CO2BOL solvents. Previous work established the thermodynamic properties related to CO 2 capture. The present paper quantitatively studies the kinetics of CO 2 capture and develops a rate-based model.« less

Endovascular vein harvest: systemic carbon dioxide absorption.

PubMed

Maslow, Andrew M; Schwartz, Carl S; Bert, Arthur; Hurlburt, Peter; Gough, Jeffrey; Stearns, Gary; Singh, Arun K

2006-06-01

Endovascular vein harvest (EDVH) requires CO(2) insufflation to expand the subcutaneous space, allowing visualization and dissection of the saphenous vein. The purpose of this study was to assess the extent of CO(2) absorption during EDVH. Prospective observational study. Single tertiary care hospital. Sixty patients (30 EDVH and 30 open-vein harvest) undergoing isolated coronary artery bypass graft surgery. Hemodynamic, procedural, and laboratory data were collected prior to (baseline), during, and at it the conclusion (final) of vein harvesting. Data were also collected during cardiopulmonary bypass (CPB). Data were compared by using t tests, analysis of variance, and correlation statistics when needed. There were significant increases in arterial CO(2) (PaCO(2), 35%) and decreases in pH (1.35%) during EDVH. These were associated with increases in heart rate, mean blood pressure, and cardiac output. Within the EDVH group, greater elevations (>10 mmHg) in PaCO2 were more likely during difficult harvest procedures, and these patients exhibited greater increase in heart rate. Elevated CO(2) persisted during CPB, requiring higher systemic gas flows and greater use of phenylephrine to maintain desired hemodynamics. EDVH was associated with systemic absorption of CO(2). Greater absorption was more likely in difficult procedures and was associated with greater hemodynamic changes requiring medical therapy.

Measurements of high-pressure CO2 absorption near 2.0 μm and implications on tunable diode laser sensor design

NASA Astrophysics Data System (ADS)

Rieker, G. B.; Jeffries, J. B.; Hanson, R. K.

2009-01-01

A tunable diode laser (TDL) is used to measure the absorption spectra of the R46 through R54 transitions of the 20012 ←00001 band of CO2 near 2.0 μm (5000 cm-1) at room temperature and pressures to 10 atm (densities to 9.2 amagat). Spectra are recorded using direct absorption spectroscopy and wavelength modulation spectroscopy with second-harmonic detection (WMS-2f) in a mixture containing 11% CO2 in air. The direct absorption spectra are influenced by non-Lorentzian effects including finite-duration collisions which perturb far-wing absorption, and an empirical χ-function correction to the Voigt line shape is shown to greatly reduce error in the spectral model. WMS-2f spectra are shown to be at least a factor of four less-influenced by non-Lorentzian effects in this region, making this approach more resistant to errors in the far-wing line shape model and allowing a comparison between the spectral parameters of HITRAN and a new database which includes pressure-induced shift coefficients. The implications of these measurements on practical, high-pressure CO2 sensor design are discussed.

Simultaneous sensing of temperature, CO, and CO2 in a scramjet combustor using quantum cascade laser absorption spectroscopy

NASA Astrophysics Data System (ADS)

Spearrin, R. M.; Goldenstein, C. S.; Schultz, I. A.; Jeffries, J. B.; Hanson, R. K.

2014-07-01

A mid-infrared laser absorption sensor was developed for gas temperature and carbon oxide (CO, CO2) concentrations in high-enthalpy, hydrocarbon combustion flows. This diagnostic enables non-intrusive, in situ measurements in harsh environments produced by hypersonic propulsion ground test facilities. The sensing system utilizes tunable quantum cascade lasers capable of probing the fundamental mid-infrared absorption bands of CO and CO2 in the 4-5 µm wavelength domain. A scanned-wavelength direct absorption technique was employed with two lasers, one dedicated to each species, free-space fiber-coupled using a bifurcated hollow-core fiber for remote light delivery on a single line of sight. Scanned-wavelength modulation spectroscopy with second-harmonic detection was utilized to extend the dynamic range of the CO measurement. The diagnostic was field-tested on a direct-connect scramjet combustor for ethylene-air combustion. Simultaneous, laser-based measurements of carbon monoxide and carbon dioxide provide a basis for evaluating combustion completion or efficiency with temporal and spatial resolution in practical hydrocarbon-fueled engines.

Predicting CO2 Solubility in Imidazole Ionic Liquids for Use in Absorption Refrigeration Systems by Using the Group Contribution Equation of State Method

NASA Astrophysics Data System (ADS)

Wu, Wei-Dong; Wu, Jun; Hou, Yong; Su, Lin; Zhang, Hua

2017-09-01

Traditional absorption refrigeration such as H2O-LiBr- and NH3-H2O-based refrigeration has limited applications because of several issues, including crystallization, corrosion, and large volume. CO2-ionic liquids (ILs) as new absorption working pairs were investigated in this study. The objective was to use the group contribution equation of state (GC-EOS) method to predict the solubilities of binary systems containing high-pressure CO2-imidazole bis(trifluoromethanesulfonimide) ILs and to investigate the applicability and accuracy of the GC-EOS model. The results showed that at pressures up to 11.0 MPa and temperatures of 273 K to 400 K, the CO2 solubility in the ILs increased with increasing system pressure but decreased with increasing temperature, and its variation rate was lower at higher pressures or temperatures. Also, CO2 solubility increased in the order of [emim][Tf2N] < [bmim][Tf2N] < [hmim][Tf2N] < [omim][Tf2N], indicating that longer alkyl chains of identical IL families resulted in higher CO_{2 } solubility. The model prediction of CO2 solubility in the four different ILs showed reasonable consistency with the corresponding experimental results from the literature; the largest deviation was 5.7 % for CO2-[emim][Tf2N]. Therefore, it can be concluded that the GC-EOS model is a promising theoretical solution that can be used to search for suitable CO2-IL working pairs for absorption refrigeration systems.

Laser-absorption sensing of gas composition of products from coal gasification

NASA Astrophysics Data System (ADS)

Jeffries, Jay B.; Sur, Ritobrata; Sun, Kai; Hanson, Ronald K.

2014-06-01

A prototype in-situ laser-absorption sensor for the real-time composition measurement (CO, CH4, H2O and CO2) of synthesis gas products of coal gasification (called here syngas) was designed, tested in the laboratory, and demonstrated during field-measurement campaigns in a pilot-scale entrained flow gasifier at the University of Utah and in an engineering-scale, fluidized-bed transport gasifier at the National Carbon Capture Center (NCCC). The prototype design and operation were improved by the lessons learned from each field test. Laser-absorption measurements are problematic in syngas flows because efficient gasifiers operate at elevated pressures (10-50 atm) where absorption transitions are collision broadened and absorption transitions that are isolated at 1 atm become blended into complex features, and because syngas product streams can contain significant particulate, producing significant non-absorption scattering losses of the transmission of laser light. Thus, the prototype sensor used a new wavelength-scanned, wavelength-modulation spectroscopy strategy with 2f-detection and 1f-normalization (WMS-2f/1f) that can provide sensitive absorption measurements of species with spectra blended by collision broadening even in the presence of large non-absorption laser transmission losses (e.g., particulate scattering, beam steering, etc.). The design of the sensor for detection of CO, CH4, H2O and CO2 was optimized for the specific application of syngas monitoring at the output of large-scale gasifiers. Sensor strategies, results and lessons learned from these field measurement campaigns are discussed.

Flight tests of a range-resolved airborne dial with two min-tea CO2 lasers

NASA Technical Reports Server (NTRS)

Itabe, T.; Ishizu, M.; Aruga, T.; Igarashi, T.; Asai, K.

1986-01-01

It is important to measure regional distributions of ozone concentrations in a short time for understanding a mechanism of photo-chemical smog development. An airborne Differential Absorption Lidar (DIAL) system with two low-power mini-TEA CO2 lasers was developed for measuring three-dimensional distributions of ozone in the lower troposphere. The CO2 DIAL is a nadir-looking system and is designed to measure ozone profiles between ground and airplane by using atmospheric aerosols as a distributed radar target. First flight test with a single laser were conducted in February 1985 over the Tokyo area. The system was operated at an altitude of 5000 ft. Results of the first flight tests show that the height profiles of the received power in the boundary layer were different between over land and ocean. The received power has to be inverted to an expression of a single optical parameter to see real aerosol distributions. Inversion of the lidar signal to the aerosol extinction was performed by using Klett's solution.

Measurements and modeling of absorption by CO2 + H2O mixtures in the spectral region beyond the CO2 ν3-band head

NASA Astrophysics Data System (ADS)

Tran, H.; Turbet, M.; Chelin, P.; Landsheere, X.

2018-05-01

In this work, we measured the absorption by CO2 + H2O mixtures from 2400 to 2600 cm-1 which corresponds to the spectral region beyond the ν3 band head of CO2. Transmission spectra of CO2 mixed with water vapor were recorded with a high-resolution Fourier-transform spectrometer for various pressure, temperature and concentration conditions. The continuum absorption by CO2 due to the presence of water vapor was determined by subtracting from measured spectra the contribution of local lines of both species, that of the continuum of pure CO2 as well as of the self- and CO2-continua of water vapor induced by the H2O-H2O and H2O-CO2 interactions. The obtained results are in very good agreement with the unique previous measurement (in a narrower spectral range). They confirm that the H2O-continuum of CO2 is significantly larger than that observed for pure CO2. This continuum thus must be taken into account in radiative transfer calculations for media involving CO2+ H2O mixture. An empirical model, using sub-Lorentzian line shapes based on some temperature-dependent correction factors χ is proposed which enables an accurate description of the experimental results.

Microporous Co@C Nanoparticles Prepared by Dealloying CoAl@C Precursors: Achieving Strong Wideband Microwave Absorption via Controlling Carbon Shell Thickness.

PubMed

Li, Da; Liao, Haoyan; Kikuchi, Hiroaki; Liu, Tong

2017-12-27

Excellent magnetic features make Co-based materials promising candidates as high-performance microwave absorbers. However, it is still a significant challenge for Co-based absorbers to possess high-intensity and broadband absorption simultaneously, owing to the lack of dielectric loss and impedance matching. Herein, microporous Co@C nanoparticles (NPs) with carbon shell thicknesses ranging from 1.8-4.9 nm have been successfully synthesized by dealloying CoAl@C precursors. All of the samples exhibit high microwave absorption performance. The microporous Co@C sample possessing a carbon shell of 1.8 nm exhibits the highest absorption intensity among these samples with a minimum reflection loss (RL) of -141.1 dB, whose absorption bandwidth for RL ≤ -10 dB is 7.3 GHz. As the thickness of the carbon shell increases, the absorption bandwidth of the NPs becomes wider. For the sample with the carbon shell thickness of 4.9 nm, the absorption bandwidth for RL ≤ -10 dB reaches a record high of 13.2 GHz. The outstanding microwave attenuation properties are attributed to the dielectric loss of the carbon shell, the magnetic loss of the Co core, and the cooperation of the core-shell structure and microporous morphology. The strong wideband microwave absorption of the carbon-coated microporous Co NPs highlights their potential applications in microwave absorbing systems.

Solid-State 2-Micron Laser Transmitter Advancement for Wind and Carbon Dioxide Measurements From Ground, Airborne, and Space-Based Lidar Systems

NASA Technical Reports Server (NTRS)

Singh, Upendra N.; Kavaya, Michael J.; Koch, Grady; Yu, Jirong; Ismail, Syed

2008-01-01

NASA Langley Research Center has been developing 2-micron lidar technologies over a decade for wind measurements, utilizing coherent Doppler wind lidar technique and carbon dioxide measurements, utilizing Differential Absorption Lidar (DIAL) technique. Significant advancements have been made towards developing state-of-the-art technologies towards laser transmitters, detectors, and receiver systems. These efforts have led to the development of solid-state lasers with high pulse energy, tunablility, wavelength-stability, and double-pulsed operation. This paper will present a review of these technological developments along with examples of high resolution wind and high precision CO2 DIAL measurements in the atmosphere. Plans for the development of compact high power lasers for applications in airborne and future space platforms for wind and regional to global scale measurement of atmospheric CO2 will also be discussed.

Numerical simulation of infrared radiation absorption for diagnostics of gas-aerosol medium by remote sensing data

NASA Astrophysics Data System (ADS)

Voitsekhovskaya, O. K.; Egorov, O. V.; Kashirskii, D. E.; Shefer, O. V.

2015-11-01

Calculated absorption spectra of the mixture of gases (H2O, CO, CO2, NO, NO2, and SO2) and aerosol (soot and Al2O3), contained in the exhausts of aircraft and rocket engines are demonstrated. Based on the model of gas-aerosol medium, a numerical study of the spectral dependence of the absorptance for different ratios of gas and aerosol components was carried out. The influence of microphysical and optical properties of the components of the mixture on the spectral features of absorption of gas-aerosol medium was established.

Changing noise levels in a high CO2/lower pH ocean

NASA Astrophysics Data System (ADS)

Brewer, P. G.; Hester, K. C.; Peltzer, E. T.; Kirkwood, W. J.

2008-12-01

We show that ocean acidification from fossil fuel CO2 invasion and from increased respiration/reduced ventilation, has significantly reduced ocean sound absorption and thus increased ocean noise levels in the kHz frequency range. Below 10 kHz, sound absorption occurs due to well known chemical relaxations in the B(OH)3/B(OH)4- and HCO3-/CO32- systems. The pH dependence of these chemical relaxations results in decreased sound absorption (α = dB/km) as the ocean becomes more acidic from increased CO2 levels. The scale of surface ocean pH change today from the +105 ppmv change in atmospheric CO2 is about - 0.12 pH, resulting in frequency dependent decreases in sound absorption that now exceed 12% over pre- industrial. Under reasonable projections of future fossil fuel CO2 emissions and other sources a pH change of 0.3 units or more can be anticipated by mid-century, resulting in a decrease in α by almost 40%. Increases in water temperature have a smaller effect but also contribute to decreased sound absorption. Combining a lowering of 0.3 pH units with an increase of 3°C, α will decrease further to almost 45%. Ambient noise levels in the ocean within the auditory range critical for environmental, military, and economic interests are set to increase significantly due to the combined effects of decreased absorption and increasing sources from mankind's activities. Incorporation of sound absorption in modeling future ocean scenarios (R. Zeebe, personal communication) and long-term monitoring possibly with the aid of modern cabled observatories can give insights in how ocean noise will continue to change and its effect on groups such as marine mammals which communicate in the affected frequency range.

Novel Silica Nanostructured Platforms with Engineered Surface Functionality and Spherical Morphology for Low-Cost High-Efficiency Carbon Capture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lai, Cheng-Yu; Radu, Daniela R.; Pizzi, Nicholas

Carbon capture is an integral part of the CO 2 mitigation efforts, and encompasses, among other measures, the demonstration of effective and inexpensive CO 2 capture technologies. The project demonstrated a novel platform—the amine-functionalized stellate mesoporous silica nanosphere (MSN)—for effective CO 2 absorption. The reported CO 2 absorption data are superior to the performance of other reported silica matrices utilized for carbon capture, featuring an amount of over 4 milimoles CO 2/g sorbent at low temperatures (in the range of 30-45 ºC), selected for simulating the temperature of actual flue gas. The reported platform is highly resilient, showing recyclability andmore » 85 % mass conservation of sorbent upon nine tested cycles. Importantly, the stellate MSNs show high CO 2 selectivity at room temperature, indicating that the presence of nitrogen in flue gas will not impair the CO 2 absorption performance. The results could lead to a simple and inexpensive new technology for CO 2 mitigation which could be implemented as measure of CO 2 mitigation in current fossil-fuel burning plants in the form of solid sorbent.« less

Characteristics of NaNO3-Promoted CdO as a Midtemperature CO2 Absorbent.

PubMed

Kim, Kang-Yeong; Kwak, Jin-Su; An, Young-In; Oh, Kyung-Ryul; Kwon, Young-Uk

2017-06-28

In this study, we explored the reaction system CdO(s) + CO 2 (g) ⇄ CdCO 3 (s) as a model system for CO 2 capture agent in the intermediate temperature range of 300-400 °C. While pure CdO does not react with CO 2 at all up to 500 °C, CdO mixed with an appropriate amount of NaNO 3 (optimal molar ratio NaNO 3 /CdO = 0.14) greatly enhances the conversion of CdO into CdCO 3 up to ∼80% (5.68 mmol/g). These NaNO 3 -promoted CdO absorbents can undergo many cycles of absorption and desorption by temperature swing between 300 and 370 °C under a 100% CO 2 condition. Details of how NaNO 3 promotes the CO 2 absorption of CdO have been delineated through various techniques using thermogravimetry, coupled with X-ray diffraction and electron microscopy. On the basis of the observed data, we propose a mechanism of CO 2 absorption and desorption of NaNO 3 -promoted CdO. The absorption proceeds through a sequence of events of CO 2 adsorption on the CdO surface covered by NaNO 3 , dissolution of so-formed CdCO 3 , and precipitation of CdCO 3 particles in the NaNO 3 medium. The desorption occurs through the decomposition of CdCO 3 in the dissolved state in the NaNO 3 medium where CdO nanoparticles are formed dispersed in the NaNO 3 medium. The CdO nanoparticles are aggregated into micrometer-large particles with smooth surfaces and regular shapes.

Vapochromic Behaviour of M[Au(CN)2]2-Based Coordination Polymers (M = Co, Ni)

PubMed Central

Lefebvre, Julie; Korčok, Jasmine L.; Katz, Michael J.; Leznoff, Daniel B.

2012-01-01

A series of M[Au(CN)2]2(analyte)x coordination polymers (M = Co, Ni; analyte = dimethylsulfoxide (DMSO), N,N-dimethylformamide (DMF), pyridine; x = 2 or 4) was prepared and characterized. Addition of analyte vapours to solid M(μ-OH2)[Au(CN)2]2 yielded visible vapochromic responses for M = Co but not M = Ni; the IR νCN spectral region changed in every case. A single crystal structure of Zn[Au(CN)2]2(DMSO)2 revealed a corrugated 2-D layer structure with cis-DMSO units. Reacting a Ni(II) salt and K[Au(CN)2] in DMSO yielded the isostructural Ni[Au(CN)2]2(DMSO)2 product. Co[Au(CN)2]2(DMSO)2 and M[Au(CN)2]2(DMF)2 (M = Co, Ni) complexes have flat 2-D square-grid layer structures with trans-bound DMSO or DMF units; they are formed via vapour absorption by solid M(μ-OH2)[Au(CN)2]2 and from DMSO or DMF solution synthesis. Co[Au(CN)2]2(pyridine)4 is generated via vapour absorption by Co(μ-OH2)[Au(CN)2]2; the analogous Ni complex is synthesized by immersion of Ni(μ-OH2)[Au(CN)2]2 in 4% aqueous pyridine. Similar immersion of Co(μ-OH2)[Au(CN)2]2 yielded Co[Au(CN)2]2(pyridine)2, which has a flat 2-D square-grid structure with trans-pyridine units. Absorption of pyridine vapour by solid Ni(μ-OH2)[Au(CN)2]2 was incomplete, generating a mixture of pyridine-bound complexes. Analyte-free Co[Au(CN)2]2 was prepared by dehydration of Co(μ-OH2)[Au(CN)2]2 at 145 °C; it has a 3-D diamondoid-type structure and absorbs DMSO, DMF and pyridine to give the same materials as by vapour absorption from the hydrate. PMID:22737031

Near-infrared spectra of the Martian surface: Reading between the lines

NASA Technical Reports Server (NTRS)

Crisp, D.; Bell, J. F., III

1993-01-01

Moderate-resolution near-infrared (NIR) spectra of Mars have been widely used in studies of the Martian surface because many candidate surface materials have distinctive absorption features at these wavelengths. Recent advances in NIR detector technology and instrumentation have also encouraged studies in this spectral region. The use of moderate spectral resolution has often been justified for NIR surface observations because the spectral features produced by most surface materials are relatively broad, and easily discriminated at this resolution. In spite of this, NIR spectra of Mars are usually very difficult to interpret quantitatively. One problem is that NIR surface absorption features are often only a few percent deep, requiring observations with great signal-to-noise ratios. A more significant problem is that gases in the Martian atmosphere contribute numerous absorption features at these wavelengths. Ground-based observers must also contend with variable absorption by several gases in the Earth's atmosphere (H2O, CO2, O3, N2O, CH4, O2). The strong CO2 bands near 1.4, 1.6, 2.0, 2.7, 4.3, and 4.8 micrometers largely preclude the analysis of surface spectral features at these wavelengths. Martian atmospheric water vapor also contributes significant absorption near 1.33, 1.88, and 2.7 micrometers, but water vapor in the Earth's atmosphere poses a much larger problem to ground-based studies of these spectral regions. The third most important NIR absorber in the Martian atmosphere is CO. This gas absorbs most strongly in the relatively-transparent spectral windows near 4.6 and 2.3 micrometers. It also produces 1-10 percent absorption in the solar spectrum at these NIR wavelengths. This solar CO absorption cannot be adequately removed by dividing the Martian spectrum by that of a star, as is commonly done to calibrate ground-based spectroscopic observations, because most stars do not have identical amounts of CO absorption in their spectra. Here, we describe tow effective methods for eliminating contamination of Martian surface spectra by absorption in the solar, terrestrial, and Martian atmospheres. Both methods involve the use of very-high-resolution spectra that completely resolve the narrow atmospheric absorption lines.

Femtosecond Photolysis of CO-Ligated Protoheme and Hemoproteins: Appearance of Deoxy Species with a 350-Fsec Time Constant

NASA Astrophysics Data System (ADS)

Martin, J. L.; Migus, A.; Poyart, C.; Lecarpentier, Y.; Astier, R.; Antonetti, A.

1983-01-01

Photolysis of HbCO, MbCO, and CO-protoheme has been investigated by measuring transient differential spectra and kinetics of induced absorption after excitation with a 250-fsec laser pulse at 307 nm. Probing was performed by a part of a continuum pulse between 395 and 445 nm. Photodissociation of the three liganded species occurred within the pulse duration. By contrast, the formation of deoxy species appeared with a mean (± SD) response time of 350± 50 fsec. This time constant was identical for the three species and independent of the presence or absence of the protein structure. Our results suggest the formation of a transient high-spin in plane iron (II) species which relaxes in 350 fsec to a high-spin stable state with concerted kinetics of CO departure and iron displacement. The spin transition is suspected to occur via liganded excited states which relax in part to nonreactive states with a 3,2-psec time constant.

Catalysis of CO₂ absorption in aqueous solution by inorganic oxoanions and their application to post combustion capture.

PubMed

Phan, Duong T; Maeder, Marcel; Burns, Robert C; Puxty, Graeme

2014-04-15

To reduce CO2 emission into the atmosphere, particularly from coal-fired power stations, post combustion capture (PCC) using amine-based solvents to chemically absorb CO2 has been extensively developed. From an infrastructure viewpoint, the faster the absorption of CO2, the smaller the absorber required. The use of catalysts for this process has been broadly studied. In this manuscript, a study of the catalytic efficiencies of inorganic oxoanions such as arsenite, arsenate, phosphite, phosphate, and borate is described. The kinetics of the accelerated CO2 absorption at 25 °C was investigated using stopped-flow spectrophotometry. The catalytic rate constants of these anions for the reaction of CO2 with H2O were determined to be 137.7(3), 30.3(7), 69(2), 32.7(9), and 13.66(7) M(-1)s(-1), respectively. A new mechanism for the catalytic reaction of oxoanions with CO2 has also been proposed. The applicability of these catalysts to PCC was further studied by simulation of the absorption process under PCC conditions using their experimental catalytic rate constants. Arsenite and phosphite were confirmed to be the best catalysts for CO2 capture. However, considering the toxicological effect of arsenic and the oxidative instability of phosphite, phosphate would be the most promising inorganic catalyst for PCC process from the series of inorganic oxoanions studied.

Closing CO2 Loop in Biogas Production: Recycling Ammonia As Fertilizer.

PubMed

He, Qingyao; Yu, Ge; Tu, Te; Yan, Shuiping; Zhang, Yanlin; Zhao, Shuaifei

2017-08-01

We propose and demonstrate a novel system for simultaneous ammonia recovery, carbon capture, biogas upgrading, and fertilizer production in biogas production. Biogas slurry pretreatment (adjusting the solution pH, turbidity, and chemical oxygen demand) plays an important role in the system as it significantly affects the performance of ammonia recovery. Vacuum membrane distillation is used to recover ammonia from biogas slurry at various conditions. The ammonia removal efficiency in vacuum membrane distillation is around 75% regardless of the ammonia concentration of the biogas slurry. The recovered ammonia is used for CO 2 absorption to realize simultaneous biogas upgrading and fertilizer generation. CO 2 absorption performance of the recovered ammonia (absorption capacity and rate) is compared with a conventional model absorbent. Theoretical results on biogas upgrading are also provided. After ammonia recovery, the treated biogas slurry has significantly reduced phytotoxicity, improving the applicability for agricultural irrigation. The novel concept demonstrated in this study shows great potential in closing the CO 2 loop in biogas production by recycling ammonia as an absorbent for CO 2 absorption associated with producing fertilizers.

Laser Sounder for Global Measurement of CO2 Concentrations in the Troposphere from Space: Progress

NASA Technical Reports Server (NTRS)

Abshire, J. B.; Krainak, M.; Riris, H. J.; Sun, X.; Riris, H.; Andrews, A. E.; Collatz, J.

2004-01-01

We describe progress toward developing a laser-based technique for the remote measurement of the tropospheric CO2 concentrations from orbit. Our goal is to demonstrate a lidar technique and instrument technology that will permit measurements of the CO2 column abundance in the lower troposphere from aircraft at the few ppm level, with a capability of scaling to permit global CO2 measurements from orbit. Accurate measurements of the tropospheric CO2 mixing ratio from space are challenging due to the many potential error sources. These include possible interference from other trace gas species, the effects of temperature, clouds, aerosols & turbulence in the path, changes in surface reflectivity, and variability in dry air density caused by changes in atmospheric pressure, water vapor and topographic height. Some potential instrumental errors include frequency drifts in the transmitter, small transmission and sensitivity drifts in the instrument. High signal-to-noise ratios and measurement stability are needed for mixing ratio estimates at the few ppm level. We have been developing a laser sounder approach as a candidate for a future space mission. It utilizes multiple different laser transmitters to permit simultaneous measurement of CO2 and O2 extinction, and aerosol backscatter in the same measurement path. It directs the narrow co-aligned laser beams from the instrument's fiber lasers toward nadir, and measures the energy of the strong laser echoes reflected from the Earth's land and water surfaces. During the measurement its narrow linewidth lasers are rapidly tuned on- and off- selected CO2 line near 1572 nm and an O2 absorption line near 770 nm. The receiver measures the energies of the laser echoes from the surface and any clouds and aerosols in the path with photon counting detectors. Ratioing the on- to off-line echo pulse energies for each gas permits the column extinction and column densities of CO2 and O2 to be estimated simultaneously via the differential absorption lidar technique. For the on-line wavelengths, the side of the selected absorption lines are used, which due to pressure broadening, weights the measurements to the lower troposphere, where CO2 variations caused by surface sources and sinks are largest. Simultaneous measurements of O2 column abundance are made using an identical approach using an O2 line. The laser backscatter profiles from clouds and aerosols are measured with other lidar channels, which permits identifying measurements influenced by clouds and/or aerosol scattering in the path. For space use, our lidar would continuously measure at nadir in near polar circular orbit. Using dawn and dusk measurements made over the same region will make it possible to sample the diurnal variations in CO2 mixing ratios. A 1-m diameter telescope is used for the receiver for all wavelengths. When averaging over 50 seconds, our calculations show a SNR of approximately 1500 is achievable for each gas at each on- and off-line measurement. Measurements from such a mission can be used to generate monthly global maps of the lower tropospheric CO2 column abundance. Our calculations show global coverage with an accuracy of a few ppm with a spatial resolution of approximately 50,000 sq. km are achievable each month. We have demonstrated some key elements of the laser, detector and receiver approaches in the laboratory and with measurements over a 206 m horizontal path. These include stable measurements of CO2 line shapes in an absorption cell using a fiber laser amplifier seeded by a tunable diode laser, measurement of small amplitude changes at low optical signal levels with the PMT receiver, and comparison of the horizontal path measurements of CO2 against those from an in-situ instrument.

Regenerable sorbent technique for capturing CO.sub.2 using immobilized amine sorbents

DOEpatents

Pennline, Henry W; Hoffman, James S; Gray, McMahan L; Fauth, Daniel J; Resnik, Kevin P

2013-08-06

The disclosure provides a CO.sub.2 absorption method using an amine-based solid sorbent for the removal of carbon dioxide from a gas stream. The method disclosed mitigates the impact of water loading on regeneration by utilizing a conditioner following the steam regeneration process, providing for a water loading on the amine-based solid sorbent following CO.sub.2 absorption substantially equivalent to the moisture loading of the regeneration process. This assists in optimizing the CO.sub.2 removal capacity of the amine-based solid sorbent for a given absorption and regeneration reactor size. Management of the water loading in this manner allows regeneration reactor operation with significant mitigation of energy losses incurred by the necessary desorption of adsorbed water.

A Comparative Study of the CO2 Absorption in Some Solvent-Free Alkanolamines and in Aqueous Monoethanolamine (MEA).

PubMed

Barzagli, Francesco; Mani, Fabrizio; Peruzzini, Maurizio

2016-07-05

The neat secondary amines 2-(methylamino)ethanol, 2-(ethylamino)ethanol, 2-(isopropylamino)ethanol, 2-(benzylamino)ethanol and 2-(butylamino)ethanol react with CO2 at 50-60 °C and room pressure yielding liquid carbonated species without their dilution with any additional solvent. These single-component absorbents have the theoretical CO2 capture capacity of 0.50 (mol CO2/mol amine) due to the formation of the corresponding amine carbamates and protonated amines that were identified by the (13)C NMR analysis. These single-component absorbents were used for CO2 capture (15% and 40% v/v in air) in two series of different procedures: (1) batch experiments aimed at investigating the efficiency and the rate of CO2 capture; (2) continuous cycles of absorption-desorption carried out in packed columns with absorption temperatures brought at 50-60 °C and desorption temperatures at 100-120 °C at room pressure. A number of different amines and experimental setups gave CO2 capture efficiency greater than 90%. For comparison purposes, 30 wt % aqueous MEA was used for CO2 capture under the same operational conditions described for the solvent-free amines. The potential advantages of solvent-free alkanolamines over aqueous MEA in the CO2 capture process were discussed.

Molecular insights into the enhanced rate of CO2 absorption to produce bicarbonate in aqueous 2-amino-2-methyl-1-propanol.

PubMed

Stowe, Haley M; Hwang, Gyeong S

2017-12-06

2-Amino-2-methyl-1-propanol (AMP), a sterically hindered amine, exhibits a much higher CO 2 absorption rate relative to tertiary amine diethylethanolamine (DEEA), while both yield bicarbonate as a major product in aqueous solution, despite their similar basicity. We present molecular mechanisms underlying the significant difference of CO 2 absorption rate based on ab initio molecular dynamics simulations combined with metadynamics. Our calculations predict the free energy barrier for base-catalyzed CO 2 hydration to be lower in aqueous AMP compared to DEEA. Further molecular analysis suggests that the difference in free energy barrier is largely attributed to entropic effects associated with reorganization of H 2 O molecules adjacent to the basic N site. Stronger hydrogen bonding of H 2 O with N of DEEA than AMP, in addition to the presence of bulky ethyl groups, suppresses the thermal rearrangement of adjacent H 2 O molecules, thereby leading to lower stability of the transition state involving OH - creation and CO 2 polarization. Moreover, the hindered reorganization of adjacent H 2 O molecules is found to facilitate migration of OH - (created via proton abstraction by DEEA) away from the N site while suppressing CO 2 approach. This leads us to speculate that catalyzed CO 2 hydration in aqueous DEEA may involve OH - migration through multiple hydrogen-bonded H 2 O molecules prior to reaction with CO 2 , whereas in aqueous AMP it seems to preferentially follow the one H 2 O-mediated mechanism. This study highlights the importance of entropic effects in determining both mechanisms and rates of CO 2 absorption into aqueous sterically hindered amines.

Ultraviolet absorption cross-sections of hot carbon dioxide

NASA Astrophysics Data System (ADS)

Oehlschlaeger, Matthew A.; Davidson, David F.; Jeffries, Jay B.; Hanson, Ronald K.

2004-12-01

The temperature-dependent ultraviolet absorption cross-section for CO 2 has been measured in shock-heated gases between 1500 and 4500 K at 216.5, 244, 266, and 306 nm. Continuous-wave lasers provide the spectral brightness to enable precise time-resolved measurements with the microsecond time-response needed to monitor thermal decomposition of CO 2 at temperatures above 3000 K. The photophysics of the highly temperature dependent cross-section is discussed. The new data allows the extension of CO 2 absorption-based temperature sensing methods to higher temperatures, such as those found in behind detonation waves.

Performance of a biogas upgrading process based on alkali absorption with regeneration using air pollution control residues.

PubMed

Baciocchi, Renato; Carnevale, Ennio; Costa, Giulia; Gavasci, Renato; Lombardi, Lidia; Olivieri, Tommaso; Zanchi, Laura; Zingaretti, Daniela

2013-12-01

This work analyzes the performance of an innovative biogas upgrading method, Alkali absorption with Regeneration (AwR) that employs industrial residues and allows to permanently store the separated CO2. This process consists in a first stage in which CO2 is removed from the biogas by means of chemical absorption with KOH or NaOH solutions followed by a second stage in which the spent absorption solution is contacted with waste incineration Air Pollution Control (APC) residues. The latter reaction leads to the regeneration of the alkali reagent in the solution and to the precipitation of calcium carbonate and hence allows to reuse the regenerated solution in the absorption process and to permanently store the separated CO2 in solid form. In addition, the final solid product is characterized by an improved environmental behavior compared to the untreated residues. In this paper the results obtained by AwR tests carried out in purposely designed demonstrative units installed in a landfill site are presented and discussed with the aim of verifying the feasibility of this process at pilot-scale and of identifying the conditions that allow to achieve all of the goals targeted by the proposed treatment. Specifically, the CO2 removal efficiency achieved in the absorption stage, the yield of alkali regeneration and CO2 uptake resulting for the regeneration stage, as well as the leaching behavior of the solid product are analyzed as a function of the type and concentration of the alkali reagent employed for the absorption reaction. Copyright © 2013 Elsevier Ltd. All rights reserved.

Study of CO2 cyclic absorption stability of CaO-based sorbents derived from lime mud purified by sucrose method.

PubMed

Ma, AiHua; Jia, QingMing; Su, HongYing; Zhi, YunFei; Tian, Na; Wu, Jing; Shan, ShaoYun

2016-02-01

Using lime mud (LM) purified by sucrose method, derived from paper-making industry, as calcium precursor, and using mineral rejects-bauxite-tailings (BTs) from aluminum production as dopant, the CaO-based sorbents for high-temperature CO2 capture were prepared. Effects of BTs content, precalcining time, and temperature on CO2 cyclic absorption stability were illustrated. The cyclic carbonation behavior was investigated in a thermogravimetric analyzer (TGA). Phase composition and morphologies were analyzed by XRD and SEM. The results reflected that the as-synthesized CaO-based sorbent doped with 10 wt% BTs showed a superior CO2 cyclic absorption-desorption conversion during multiple cycles, with conversion being >38 % after 50 cycles. Occurrence of Ca12Al14O33 phase during precalcination was probably responsible for the excellent CO2 cyclic stability.

Enhanced CO2 capture in binary mixtures of 1-alkyl-3-methylimidazolium tricyanomethanide ionic liquids with water.

PubMed

Romanos, George E; Zubeir, Lawien F; Likodimos, Vlassis; Falaras, Polycarpos; Kroon, Maaike C; Iliev, Boyan; Adamova, Gabriela; Schubert, Thomas J S

2013-10-10

Absorption of carbon dioxide and water in 1-butyl-3-methylimidazoliun tricyanomethanide ([C4C1im][TCM]) and 1-octyl-3-methylimidazolium tricyanomethanide ([C8C1im][TCM]) ionic liquids (ILs) was systematically investigated for the first time as a function of the H2O content by means of a gravimetric system together with in-situ Raman spectroscopy, excess molar volume (V(E)), and viscosity deviation measurements. Although CO2 absorption was marginally affected by water at low H2O molar fractions for both ILs, an increase of the H2O content resulted in a marked enhancement of both the CO2 solubility (ca. 4-fold) and diffusivity (ca. 10-fold) in the binary [C(n)C1im][TCM]/H2O systems, in contrast to the weak and/or detrimental influence of water in most physically and chemically CO2-absorbing ILs. In-situ Raman spectroscopy on the IL/CO2 systems verified that CO2 is physically absorbed in the dry ILs with no significant effect on their structural organization. A pronounced variation of distinct tricyanomethanide Raman modes was disclosed in the [C(n)C1im][TCM]/H2O mixtures, attesting to the gradual disruption of the anion-cation coupling by the hydrogen-bonded water molecules to the [TCM](-) anions, in accordance with the positive excess molar volumes and negative viscosity deviations for the binary systems. Most importantly, CO2 absorption in the ILs/H2O mixtures at high water concentrations revealed that the [TCM](-) Raman modes tend to restore their original state for the heavily hydrated ILs, in qualitative agreement with the intriguing nonmonotonous transients of CO2 absorption kinetics unveiled by the gravimetric measurements for the hybrid solvents. A molecular exchange mechanism between CO2 in the gas phase and H2O in the liquid phase was thereby proposed to explain the enhanced CO2 absorption in the hybrid [C(n)C1im][TCM]//H2O solvents based on the subtle competition between the TCM-H2O and TCM-CO2 interactions, which renders these ILs very promising for CO2 separation applications.

Detection and monitoring of H2O and CO2 ice clouds on Mars

USGS Publications Warehouse

Bell, J.F.; Calvin, W.M.; Ockert-Bell, M. E.; Crisp, D.; Pollack, James B.; Spencer, J.

1996-01-01

We have developed an observational scheme for the detection and discrimination of Mars atmospheric H2O and CO2 clouds using ground-based instruments in the near infrared. We report the results of our cloud detection and characterization study using Mars near IR images obtained during the 1990 and 1993 oppositions. We focused on specific wavelengths that have the potential, based on previous laboratory studies of H2O and CO2 ices, of yielding the greatest degree of cloud detectability and compositional discriminability. We have detected and mapped absorption features at some of these wavelengths in both the northern and southern polar regions of Mars. Compositional information on the nature of these absorption features was derived from comparisons with laboratory ice spectra and with a simplified radiative transfer model of a CO2 ice cloud overlying a bright surface. Our results indicate that both H2O and CO2 ices can be detected and distinguished in the polar hood clouds. The region near 3.00 ??m is most useful for the detection of water ice clouds because there is a strong H2O ice absorption at this wavelength but only a weak CO2 ice band. The region near 3.33 ??m is most useful for the detection of CO2 ice clouds because there is a strong, relatively narrow CO2 ice band at this wavelength but only broad "continuum" H2O ice absorption. Weaker features near 2.30 ??m could arise from CO2 ice at coarse grain sizes, or surface/dust minerals. Narrow features near 2.00 ??m, which could potentially be very diagnostic of CO2 ice clouds, suffer from contamination by Mars atmospheric CO2 absorptions and are difficult to interpret because of the rather poor knowledge of surface elevation at high latitudes. These results indicate that future ground-based, Earth-orbital, and spacecraft studies over a more extended span of the seasonal cycle should yield substantial information on the style and timing of volatile transport on Mars, as well as a more detailed understanding of the role of CO2 condensation in the polar heat budget. Copyright 1996 by the American Geophysical Union.

Atlas of absorption lines from 0 to 17 900 cm(-1)

NASA Technical Reports Server (NTRS)

Park, J. H.; Rothman, L. S.; Rinsland, C. P.; Smith, M. A. H.; Richardson, D. J.; Larsen, J. C.

1981-01-01

Plots of absorption line strength versus line position for wavenumbers from 0 to 17,900 cm(-1) are shown for 20 atmospheric gases (H2O, CO2, O3, N2O, CO, CH4, O2, NO, SO2, NO2, NH3, HNO3, OH, HF, HCl, HBr, HI, ClO, OCS, H2CO). Also shown are similar plots of lower-state energy values for adsorption lines for the strongly adsorbing atmospheric gases (H2O, CO2, O3, and CH4) for wavenumbers from 0 to 5000 cm(-1).

A generic analysis of energy use and solvent selection for CO2 separation from post-combustion flue gases

USGS Publications Warehouse

Lu, Y.; Chen, S.; Rostam-Abadi, M.

2008-01-01

A thermodynamic calculation was performed to determine the theoretical minimum energy used to separate CO2 from a coal combustion flue gas in a typical adsorption-desorption system. Under ideal conditions, the minimum energy required to separate CO2 from post-combustion flue gas and produce pure CO2 at 1 atmospheric pressure was only about 1183 kJ/kg CO2. This amount could double with the addition of the driving forces of mass and heat transfer and the adverse impacts of absorption heat release on adsorption capacity. Thermodynamic analyses were also performed for the aqueous amine-based absorption process. Two CO2 reaction mechanisms, the carbamate formation reaction with primary/secondary amines and the CO2 hydration reaction with tertiary amines, were included in the absorption reaction. The reaction heat, sensible heat, and stripping heat were all important to the total heat requirement. The heat use of an ideal tertiary amine amounted to 2786 kJ/kg, compared to 3211 kJ/kg for an ideal primary amine. The heat usage of an ideal amine was about 20% lower than that of commercially available amines. Optimizing the absorption process configuration could further reduce energy use. This is an abstract of a paper presented at the 2008 AIChE Spring National Meeting (New Orleans, LA 4/6-10/2008).

Development of Detailed and Reduced Kinetics Mechanisms for Surrogates of Petroleum-Derived and Synthetic Jet Fuels

DTIC Science & Technology

2011-02-28

Meeting of Combustion, Atlanta, Georgia, paper 2A18, March 20-23, 2011. 9.2 Web Releases Sirjean, B., Dames, A., Sheen, D.A., You, X.-Q., Sung, C...was no significant interfering absorption or emission. IR diode laser absorption of CO2 and H2O: The recent commercial availability of DFB...distributed feedback) IR diode lasers in the wavelength vicinity of 2.5-2.7 microns has allowed the development of a new CO2 and H2O absorption diagnostics

Absorption coefficients and frequency shifts measurement in the spectral range of 1071.88-1084.62 cm-1 vs. pressure for chlorodifluoromethane (CHClF2) using tunable CW CO2 laser

NASA Astrophysics Data System (ADS)

Al-Hawat, Sharif

2013-02-01

Infrared (IR) absorption in the spectral range of (1071.88-1084.62 cm-1) vs. pressure in chlorodifluoromethane (CFC-22, F-22, and CHClF2) was studied using a tunable continuous wave (CW) CO2 laser radiation on 9R branch lines with a maximum output power of about 2.12 W, provided with an absorber cell located outside the laser cavity. The absorption coefficients were determined vs. the gas pressure between 0.2 mbar and 170 mbar at lines from 9R branch for CFC-22. The frequency shifts of the absorption lines of CFC-22 in relative to the central frequencies of laser lines were calculated vs. the pressure on the basis of these absorption coefficients. The chosen lines were selected according to IR spectrum of the studied gas given by HITRAN cross section database. So the absorption was achieved for CFC-22 at the spectral lines of 9R branch situated from 9R (10) to 9R (30) emitted by a tunable CW CO2 laser. The absorption cross sections of CFC-22 determined in this work were compared with the relevant data given by HITRAN cross section database and a reasonable agreement was observed.

Spectroscopy of Reaction Intermediates in Nitramine Decomposition and Combustion

DTIC Science & Technology

1991-06-20

Dakhis and co-workers, s the very strong absorption of MMN near 1332 cm - 1 did not appear. Unassigned absorptions appeared near 930, 1240, 1460, 2990, and...sharp NO2 absorption. In Table I, the positions of these absorptions are compared with the infrared absorptions of MMN reported by Dakhis and co-workers...Chemistry and Physics of Energetic Materials, S. N. Bulusu, Ed., pp. 51-78 (Kluwer Academic Publishers, Dordrecht, 1990). 56. M. I. Dakhis , V. G. Dashevsky

Spectroscopy of Reaction Intermediates in Nitramine Decomposition and Combustion

DTIC Science & Technology

1991-06-20

absorptions of gas-phase MMN reported by Dakhis and co-workers,5 6 the very strong absorption of MMN near 1332 cm - ’ did not appear. Unassigned...sharp NO 2 absorption. In Table I, the positions of these absorptions are compared with the infrared absorptions of MMN reported by Dakhis and co-workers...Chemistry and Physics of Energetic Materials, S. N. Bulusu, Ed., pp. 51-78 (Kluwer Academic Publishers, Dordrecht, 1990). 56. M. I. Dakhis , V. G

Step-scan differential Fourier transform infrared photoacoustic spectroscopy (DFTIR-PAS): a spectral deconvolution method for weak absorber detection in the presence of strongly overlapping background absorptions.

PubMed

Liu, Lixian; Mandelis, Andreas; Huan, Huiting; Michaelian, Kirk H

2017-04-01

The determination of small absorption coefficients of trace gases in the atmosphere constitutes a challenge for analytical air contaminant measurements, especially in the presence of strongly absorbing backgrounds. A step-scan differential Fourier transform infrared photoacoustic spectroscopy (DFTIR-PAS) method was developed to suppress the coherent external noise and spurious photoacoustic (PA) signals caused by strongly absorbing backgrounds. The infrared absorption spectra of acetylene (C₂H₂) and local air were used to verify the performance of the step-scan DFTIR-PAS method. A linear amplitude response to C₂H₂ concentrations from 100 to 5000 ppmv was observed, leading to a theoretical detection limit of 5 ppmv. The differential mode was capable of eliminating the coherent noise and dominant background gas signals, thereby revealing the presence of the otherwise hidden C₂H₂ weak absorption. Thus, the step-scan DFTIR-PAS modality was demonstrated to be an effective approach for monitoring weakly absorbing gases with absorption bands overlapped by strongly absorbing background species.

Venturi Air-Jet Vacuum Ejector For Sampling Air

NASA Technical Reports Server (NTRS)

Hill, Gerald F.; Sachse, Glen W.; Burney, L. Garland; Wade, Larry O.

1990-01-01

Venturi air-jet vacuum ejector pump light in weight, requires no electrical power, does not contribute heat to aircraft, and provides high pumping speeds at moderate suctions. High-pressure motive gas required for this type of pump bled from compressor of aircraft engine with negligible effect on performance of engine. Used as source of vacuum for differential-absorption CO-measurement (DACOM), modified to achieve in situ measurements of CO at frequency response of 10 Hz. Provides improvement in spatial resolution and potentially leads to capability to measure turbulent flux of CO by use of eddy-correlation technique.

Cobalt Oxide Nanoclusters on Rutile Titania as Bifunctional Units for Water Oxidation Catalysis and Visible Light Absorption: Understanding the Structure-Activity Relationship.

PubMed

Maeda, Kazuhiko; Ishimaki, Koki; Okazaki, Megumi; Kanazawa, Tomoki; Lu, Daling; Nozawa, Shunsuke; Kato, Hideki; Kakihana, Masato

2017-02-22

The structure of cobalt oxide (CoO x ) nanoparticles dispersed on rutile TiO 2 (R-TiO 2 ) was characterized by X-ray diffraction, UV-vis-NIR diffuse reflectance spectroscopy, high-resolution transmission electron microscopy, X-ray absorption fine-structure spectroscopy, and X-ray photoelectron spectroscopy. The CoO x nanoparticles were loaded onto R-TiO 2 by an impregnation method from an aqueous solution containing Co(NO 3 ) 2 ·6H 2 O followed by heating in air. Modification of the R-TiO 2 with 2.0 wt % Co followed by heating at 423 K for 1 h resulted in the highest photocatalytic activity with good reproducibility. Structural analyses revealed that the activity of this photocatalyst depended strongly on the generation of Co 3 O 4 nanoclusters with an optimal distribution. These nanoclusters are thought to interact with the R-TiO 2 surface, resulting in visible light absorption and active sites for water oxidation.

Single-ended mid-infrared laser-absorption sensor for simultaneous in situ measurements of H₂O, CO₂, CO, and temperature in combustion flows.

PubMed

Peng, Wen Yu; Goldenstein, Christopher S; Mitchell Spearrin, R; Jeffries, Jay B; Hanson, Ronald K

2016-11-20

The development and demonstration of a four-color single-ended mid-infrared tunable laser-absorption sensor for simultaneous measurements of H₂O, CO₂, CO, and temperature in combustion flows is described. This sensor operates by transmitting laser light through a single optical port and measuring the backscattered radiation from within the combustion device. Scanned-wavelength-modulation spectroscopy with second-harmonic detection and first-harmonic normalization (scanned-WMS-2f/1f) was used to account for variable signal collection and nonabsorption losses in the harsh environment. Two tunable diode lasers operating near 2551 and 2482 nm were utilized to measure H₂O concentration and temperature, while an interband cascade laser near 4176 nm and a quantum cascade laser near 4865 nm were used for measuring CO₂ and CO, respectively. The lasers were modulated at either 90 or 112 kHz and scanned across the peaks of their respective absorption features at 1 kHz, leading to a measurement rate of 2 kHz. A hybrid demultiplexing strategy involving both spectral filtering and frequency-domain demodulation was used to decouple the backscattered radiation into its constituent signals. Demonstration measurements were made in the exhaust of a laboratory-scale laminar methane-air flat-flame burner at atmospheric pressure and equivalence ratios ranging from 0.7 to 1.2. A stainless steel reflective plate was placed 0.78 cm away from the sensor head within the combustion exhaust, leading to a total absorption path length of 1.56 cm. Detection limits of 1.4% H₂O, 0.6% CO₂, and 0.4% CO by mole were reported. To the best of the authors' knowledge, this work represents the first demonstration of a mid-infrared laser-absorption sensor using a single-ended architecture in combustion flows.

Response surface method for modeling the removal of carbon dioxide from a simulated gas using water absorption enhanced with a liquid-film-forming device.

PubMed

Nguyen, Diem-Mai Kim; Imai, Tsuyoshi; Dang, Thanh-Loc Thi; Kanno, Ariyo; Higuchi, Takaya; Yamamoto, Koichi; Sekine, Masahiko

2018-03-01

This paper presents the results from using a physical absorption process to absorb gaseous CO 2 mixed with N 2 using water by producing tiny bubbles via a liquid-film-forming device (LFFD) that improves the solubility of CO 2 in water. The influence of various parameters-pressure, initial CO 2 concentration, gas-to-liquid ratios, and temperature-on the CO 2 removal efficiency and its absorption rate in water were investigated and estimated thoroughly by statistical polynomial models obtained by the utilization of the response surface method (RSM) with a central composite design (CCD). Based on the analysis, a high efficiency of CO 2 capture can be reached in conditions such as low pressure, high CO 2 concentration at the inlet, low gas/liquid ratio, and low temperature. For instance, the highest removal efficiency in the RSM-CCD experimental matrix of nearly 80% occurred for run number 20, which was conducted at 0.30MPa, CO 2 concentration of 35%, gas/liquid ratio of 0.71, and temperature of 15°C. Furthermore, the coefficients of determination, R 2 , were 0.996 for the removal rate and 0.982 for the absorption rate, implying that the predicted values computed by the constructed models correlate strongly and fit well with the experimental values. The results obtained provide essential information for implementing this method properly and effectively and contribute a promising approach to the problem of CO 2 capture in air pollution treatment. Copyright © 2017. Published by Elsevier B.V.

Water vapor absorption coefficients in the 8-13-micron spectral region - A critical review

NASA Technical Reports Server (NTRS)

Grant, William B.

1990-01-01

Measurements of water vapor absorption coefficients in the thermal IR atmospheric window (8-13 microns) during the past 20 years obtained by a variety of techniques are reviewed for consistency and compared with computed values based on the AFGL spectral data tapes. The methods of data collection considered were atmospheric long path absorption with a CO2 laser or a broadband source and filters, a White cell and a CO2 laser or a broadband source and a spectrometer, and a spectrophone with a CO2 laser. Advantages and disadvantages of each measurement approach are given as a guide to further research. Continuum absorption has apparently been measured accurately to about the 5-10 percent level in five of the measurements reported.

Measurements of NH 3 and CO 2 with Distributed-Feedback Diode Lasers Near 2.0 m in Bioreactor Vent Gases

NASA Astrophysics Data System (ADS)

Webber, Michael E.; Claps, Ricardo; Englich, Florian V.; Tittel, Frank K.; Jeffries, Jay B.; Hanson, Ronald K.

2001-08-01

Measurements of NH3 and CO2 were made in bioreactor vent gases with distributed-feedback diode-laser sensors operating near 2 m. Calculated spectra of NH3 and CO2 were used to determine the optimum transitions for interrogating with an absorption sensor. For ammonia, a strong and isolated absorption transition at 5016.977 cm-1 was selected for trace gas monitoring. For CO2 , an isolated transition at 5007.787 cm-1 was selected to measure widely varying concentrations [500 parts per million (ppm) to 10% ,] with sufficient signal for low mole fractions and without being optically thick for high mole fractions. Using direct absorption and a 36-m total path-length multipass flow-through cell, we achieved a minimum detectivity of 0.25 ppm for NH3 and 40 ppm for CO2 . We report on the quasi-continuous field measurements of NH3 and CO2 concentration in bioreactor vent gases that were recorded at NASA Johnson Space Center with a portable and automated sensor system over a 45-h data collection window.

Crystal structure and electronic states of Co and Gd ions in a Gd0.4Sr0.6CoO2.85 single crystal

NASA Astrophysics Data System (ADS)

Platunov, M. S.; Dudnikov, V. A.; Orlov, Yu. S.; Kazak, N. V.; Solovyov, L. A.; Zubavichus, Ya. V.; Veligzhanin, A. A.; Dorovatovskii, P. V.; Vereshchagin, S. N.; Shaykhutdinov, K. A.; Ovchinnikov, S. G.

2016-02-01

X-ray diffraction and X-ray absorption near edge structure (XANES) spectra have been measured at the Co K-edge and Gd L 3-edge in GdCoO3 and Gd0.4Sr0.6CoO2.85 cobaltites. The effect of Sr substitution on the crystal structure and electronic and magnetic states of Co3+ ions in a Gd0.4Sr0.6CoO2.85 single crystal has been analyzed. The XANES measurements at the Co K-edge have not showed a noticeable shift of the absorption edge with an increase in the concentration of Sr. This indicates that the effective valence of cobalt does not change. An increase in the intensity of absorption at the Gd L 3-edge is due to an increase in the degree of hybridization of the Gd(5 d) and O(2 p) states. The effect of hole doping on the magnetic properties results in the appearance of the ferromagnetic component and in a significant increase in the magnetic moment.

Radiological responses of different types of Egyptian Mediterranean coastal sediments

NASA Astrophysics Data System (ADS)

El-Gamal, A.; Rashad, M.; Ghatass, Z.

2010-08-01

The aim of this study was to identify gamma self-absorption correction factors for different types of Egyptian Mediterranean coastal sediments. Self-absorption corrections based on direct transmission through different thicknesses of the most dominant sediment species have been tested against point sources with gamma-ray energies of 241Am, 137Cs and 60Co with 2% uncertainties. Black sand samples from the Rashid branch of the Nile River quantitatively absorbed the low energy of 241Am through a thickness of 5 cm. In decreasing order of gamma energy self-absorption of 241Am, the samples under investigation ranked black sand, Matrouh sand, Sidi Gaber sand, shells, Salloum sand, and clay. Empirical self-absorption correction formulas were also deduced. Chemical analyses such as pH, CaCO 3, total dissolved solids, Ca 2+, Mg 2+, CO 32-, HCO 3- and total Fe 2+ have been carried out for the sediments. The relationships between self absorption corrections and the other chemical parameters of the sediments were also examined.

Photoacoustic measurement of ammonia in the atmosphere: influence of water vapor and carbon dioxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rooth, R.A.; Verhage, A.J.L.; Wouters, L.W.

1990-09-01

The photoacoustic determination of the ammonia concentration in atmospheric air by absorption of CO{sub 2} laser radiation at 9.22 {mu}m is influenced by the presence of H{sub 2}O and CO{sub 2}. Kinetic cooling due to the coupling of excited CO{sub 2} and N{sub 2} levels causes important changes in phase and amplitude of the photoacoustic signal. Theoretical background is presented to deduce the correct NH{sub 3} concentration from the signal. The experimental setup used to perform field measurements is described. Adhesion of NH{sub 3} to the walls of the resonant photoacoustic cell was investigated. Temperature effects are treated. Field datamore » of NH{sub 3} and H{sub 2}O concentrations are presented. Key words: Photoacoustics, ammonia, kinetic cooling, trace gas measurements, ammonia adhesion, acoustic resonance, CO{sub 2} laser radiation, water vapor absorption, carbon dioxide absorption.« less

Effect of CO2 laser micromachining on physicochemical properties of poly(L-lactide)

NASA Astrophysics Data System (ADS)

Antończak, Arkadiusz J.; Stepak, Bogusz; Szustakiewicz, Konrad; Wójcik, Michał; Kozioł, Paweł E.; Łazarek, Łukasz; Abramski, Krzysztof M.

2014-08-01

In this paper, we present some examples of micromachining of poly(L-lactide) with a CO2 laser and an analysis of changes in material properties in the heat affected HAZ induced by the fluence well above the ablation threshold. The complexity of the processes of decomposition implies the need for simultaneous use of many selective analytical techniques which complement each other to give a full image of the changes. Introduced changes were characterized using Differential Scanning Calorimetry (DSC), Gel Permeation Chromatography (GPC), X-ray Photoelectron Spectroscopy (XPS) and Attenuated Total Reflectance Fourier Transform Infrared spectroscopy (ATR-FTIR). It turns out that CO2 laser processing of poly(L-lactide) mainly induces surface changes. However, oxidation of the surface was not observed. We recorded a bimodal distribution and some reduction in the molecular weight. Infrared spectroscopy in turn revealed the existence of absorption bands, characteristic for the vinyl groups (RCH=CH2). The appearance of these bands indicates that the decomposition of the polymer occurred, among others, by means of the cis-elimination reaction.

Simultaneous CO concentration and temperature measurements using tunable diode laser absorption spectroscopy near 2.3 μm

NASA Astrophysics Data System (ADS)

Sane, Anup; Satija, Aman; Lucht, Robert P.; Gore, Jay P.

2014-10-01

Simultaneous measurements of carbon monoxide (CO) mole fraction and temperature using tunable diode laser absorption spectroscopy (TDLAS) near 2.3 μm are reported. The measurement method uses ro-vibrational transitions [R(27): v″ = 1 → v' = 3] and [R(6): v″ = 0 → v' = 2] in the first overtone band of CO near 2.3 μm (~4,278 cm-1). The measurements were performed in the post flame environment of fuel rich premixed ethylene-air flames with a N2 co-flow, stabilized over a water cooled McKenna burner. Non-uniformity in the temperature and CO mole fraction, along the absorption line of sight, in the mixing layer of the co-flow, was considered during data analysis. The TDLAS based temperature measurements (±80 K) were in good agreement with those obtained using N2 vibrational coherent anti-Stokes Raman scattering (±20 K), and the CO mole fraction measurements were in good agreement with the equilibrium values, for equivalence ratios lower than 1.8. A signal to noise ratio of 45 was achieved at an equivalence ratio of 1 for a CO concentration of 0.8 % at 1,854 K.

Oxide ion diffusion mechanism related to Co and Fe ions in (Ba0.5Sr0.5)(Co0.8Fe0.2)O3-δ using in-situ X-ray absorption spectroscopy

NASA Astrophysics Data System (ADS)

Itoh, Takanori; Imai, Hideto

2018-03-01

The time changes of the white line and pre-edge intensities of Co and Fe K-edge in (Ba0.5Sr0.5)(Co0.8Fe0.2)O3-δ (BSCF) were observed to estimate the oxide ion diffusion related to Co and Fe ions by using in - situ X-ray absorption spectroscopy (XAS) during oxidation. The 20 μm self-standing BSCF film was prepared for in - situ XAS measurements. The time changes of absorption were fitted to the exponential decay function with two terms. The longer relaxation time (τ), related to the oxide ion diffusion during the oxidation of BSCF, is dependent on temperature. The oxide ion diffusion coefficients (D) were calculated from the τ s estimated by in - situ XAS. The values of the activation energy (Ea) for D related to Co K-edge white line, Co pre-edge, and Fe pre-edge were 1.8-2.0 eV. The value of Ea for D related to Fe K-edge white line, however, was higher than other absorption values at approximately 2.3 eV. We discussed the oxide ion diffusion mechanism related to Co and Fe ions in BSCF using in - situ XAS.

Mg,Ce co-doped Lu2Gd1(Ga,Al)5O12 by micro-pulling down method and their luminescence properties

NASA Astrophysics Data System (ADS)

Kamada, Kei; Yamaguchi, Hiroaki; Yoshino, Masao; Kurosawa, Shunsuke; Shoji, Yasuhiro; Yokota, Yuui; Ohashi, Yuji; Pejchal, Jan; Nikl, Martin; Yoshikawa, Akira

2018-04-01

The effects of Mg co-doping on the scintillation properties of Ce:Lu2Gd1(Ga,Al)5O12 (LGGAG) single crystals with different Ga/Al ratios were investigated. Mg co-doped and non co-doped Ce:LGGAG single crystals were grown by the micro-pulling down (µ-PD) method and then cut, polished and annealed for each measurement. Absorption spectra, radioluminescence (RL) spectra, pulse height spectra, and scintillation decay were measured to reveal the effect of Mg co-doping. Ce4+ charge transfer (CT) absorption band peaking at ∼260 nm was observed in Mg co-doped samples, which is in good agreement with previous reports for the Ce4+ CT absorption band in other garnet-based crystals. The scintillation decay time tended to be accelerated and the light yield tended to be decreased by Mg co-doping at higher Ga concentrations.

CO/sub 2/ absorption into aqueous MDEA and MDEA/MEA solutions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Critchfield, J.; Rochelle, G.T.

1987-01-01

The rate of absorption of CO/sub 2/ into 2 molal MDEA was measured by following solution composition in a stirred-cell batch reactor. The conditions investigated were 9.5 - 62/sup 0/C at a nominal CO/sub 2/ pressure of 1 atm. The data were modelled with a combined mass transfer and equilibrium model which treated the reaction of CO/sub 2/ with MDEA as second order and reversible, rather than pseudo-first order. The resulting activation energy was 13.7 kcal/gmol, and the rate constant at 30.5/sup 0/C was 4.0 (Ms)/sup -1/. The assumption of pseudo-first order conditions was found to reduce the apparent activationmore » energy to approximately 9 kcal/gmol. CO/sub 2/ absorption into 1.36 molal MDEA/0.61 molal MEA was studied at 31/sup 0/C. The experimental data were predicted better by a mass transfer model based on a shuttle mechanism than by one with two parallel reactions.« less

Process for CO.sub.2 capture using a regenerable magnesium hydroxide sorbent

DOEpatents

Siriwardane, Ranjani V; Stevens, Jr., Robert W

2013-06-25

A process for CO.sub.2 separation using a regenerable Mg(OH).sub.2 sorbent. The process absorbs CO.sub.2 through the formation of MgCO.sub.3 and releases water product H.sub.2O. The MgCO.sub.3 is partially regenerated through direct contact with steam, which acts to heat the magnesium carbonate to a higher temperature, provide heat duty required to decompose the magnesium carbonate to yield MgO and CO.sub.2, provide an H.sub.2O environment over the magnesium carbonate thereby shifting the equilibrium and increasing the potential for CO.sub.2 desorption, and supply H.sub.2O for rehydroxylation of a portion of the MgO. The mixture is polished in the absence of CO.sub.2 using water product H.sub.2O produced during the CO.sub.2 absorption to maintain sorbent capture capacity. The sorbent now comprised substantially of Mg(OH).sub.2 is then available for further CO.sub.2 absorption duty in a cyclic process.

Ditetraalkylammonium amino acid ionic liquids as CO₂ absorbents of high capacity.

PubMed

Ma, Jing-Wen; Zhou, Zheng; Zhang, Feng; Fang, Cheng-Gang; Wu, You-Ting; Zhang, Zhi-Bing; Li, Ai-Min

2011-12-15

By grafting butyl or ethyl onto tetramethylethylenediamine, quaternary ammonium salts with two positive charge centers were formed at the first step. Metathesis with Ag(2)O followed. Through neutralization with glycine, l-alanine, or valine, a series of new ditetraalkylammonium amino acid ionic liquids (DILs) for CO(2) capture were generated. The structures of DILs, as shown in Figure 1, were verified by using (1)H NMR and EA. These DILs were found to be of quite high viscosity which militated against their industrial application in CO(2) removal. Drawing on the experience of mixed amines' aqueous solutions, these DILs were blended with water or N-methyldiethanolamine (MDEA) aqueous solutions to act as special absorbents of CO(2). Using a Double-Tank Absorption System, the absorption performance of these DIL solutions was investigated in detail. The experimental results indicated that among the three aqueous solutions of DILs (20%, 40%, and 80 wt %), the solution of 40% DIL had a higher absorption rate of CO(2) than the other two, demonstrating the different effects of concentration and viscosity on the absorption. The solution of 40% DIL or the 15% DIL + 15% MDEA had much higher capacity for CO(2) than the corresponding monocation tetraalkylammonium AAILs, due to the special structure of the dication which could influence the solubility of CO(2) in the aqueous solution.

Solid-state Raman frequency converters for CO2-DIAL systems at 1.6 μm

NASA Astrophysics Data System (ADS)

Rhee, Hanjo; Lisinetskii, Victor; Kaminskii, Alexander A.; Eichler, Hans-Joachim

2009-09-01

Measurement of the three-dimensional distribution of atmospheric trace gases, especially CO2, is an important factor to improve the accuracy of climate models and to understand the global effects of the greenhouse effect. This can be achieved by differential absorption Lidar (DIAL). The absorption spectrum of CO2 features several suitable absorption lines for a ground-based or air-borne DIAL system working at wavelengths between 1.57 μm and 1.61 μm. An appropriate laser transmitter must emit laser pulses with pulse energies of more than 10 mJ and pulse duration in the nanosecond range. For high spectral purity the bandwidth is required to be less than 60 MHz. OPOs and Er-doped solid-state lasers emit around 1.6 μm, but we describe here alternatively Nd:YAG and Nd:glass laser systems with Raman converters. The use of stimulated Raman scattering in crystalline and ceramic materials is a possibility to shift the wavelength of existing lasers depending on the size of the Raman shift. After the investigation of a large number of Raman-active materials some of them could be identified as promising candidates for the conversion of typical Nd:YAG emission wavelengths, including LiNH2C6H4SO3•H2O, Ba(NO3)2, Li2SO4•H2O, Y(HCOO)3•2H2O, β-BBO and diamond. Our experiments with Ba(NO3)2 showed that the choice of the material should not be restricted to those with an adequate first order Stokes Raman line position, but also second or third order Raman shift should be considered. Development of Raman frequency converters for high pulse energies concentrates on linear and folded resonator designs and seeded Raman amplifiers using the Raman material as a direct amplifier. With Ba(NO3)2 pulse energy up to 116 mJ and 42 % quantum efficiency at the third Stokes wavelength with 1599 nm has been demonstrated. High power operation at 5 W with compensation of thermal lensing was achieved.

Optical absorption spectra of substitutional Co2+ ions in Mgx Cd1-x Se alloys

NASA Astrophysics Data System (ADS)

Jin, Moon-Seog; Kim, Chang-Dae; Jang, Kiwan; Park, Sang-An; Kim, Duck-Tae; Kim, Hyung-Gon; Kim, Wha-Tek

2006-09-01

Optical absorption spectra of substitutional Co2+ ions in Mgx Cd1-x Se alloys were investigated in the composition region of 0.0 x 0.4 and in the wavelength region of 300 to 2500 nm at 4.8 K and 290 K. We observed several absorption bands in the wavelength regions corresponding to the 4A2(4F) 4T1(4P) transition and the 4A2(4F) 4T1(4F) transition of Co2+ at a tetrahedral Td point symmetry point in the host crystals, as well as unknown absorption bands. The several absorption bands were analyzed in the framework of the crystal-field theory along with the second-order spin-orbit coupling. The unknown absorption bands were assigned as due to phonon-assisted absorption bands. We also investigated the variations of the crystal-field parameter Dq and the Racah parameter B with composition x in the Mgx Cd1-x Se system. The results showed that the crystal-field parameter (Dq ) increases, on the other hand, the Racah parameter (B ) decreases with increasing composition x, which may be connected with an increase in the covalency of the metal-ligand bond with increasing composition x in the Mgx Cd1-x Se system.

Na-glutamine co-transporters B(0)AT1 in villus and SN2 in crypts are differentially altered in chronically inflamed rabbit intestine.

PubMed

Saha, Prosenjit; Arthur, Subha; Kekuda, Ramesh; Sundaram, Uma

2012-03-01

Glutamine is a major nutrient utilized by the intestinal epithelium and is primarily assimilated via Na-glutamine co-transport (NGcT) on the brush border membrane (BBM) of enterocytes. Recently we reported that B(0)AT1 (SLC6A19) mediates glutamine absorption in villus while SN2 (SLC38A5) does the same in crypt cells. However, how B(0)AT1 and SN2 are affected during intestinal inflammation is unknown. In the present study it was shown that during chronic enteritis NGcT was inhibited in villus cells, however, it was stimulated in crypt cells. Our studies also demonstrated that the mechanism of inhibition of NGcT during chronic enteritis was secondary to a reduction in the number of B(0)AT1 co-transporters in the villus cell BBM without a change in the affinity of the co-transporter. In contrast, stimulation of NGcT in crypt cells was secondary to an increase in the affinity of SN2 for glutamine without an alteration in the number of co-transporters. Thus, glutamine assimilation which occurs via distinct transporters in crypt and villus cells is altered in the chronically inflamed intestine. Copyright © 2011 Elsevier B.V. All rights reserved.

The Fabrication and High-Efficiency Electromagnetic Wave Absorption Performance of CoFe/C Core-Shell Structured Nanocomposites

NASA Astrophysics Data System (ADS)

Wan, Gengping; Luo, Yongming; Wu, Lihong; Wang, Guizhen

2018-03-01

CoFe/C core-shell structured nanocomposites (CoFe@C) have been fabricated through the thermal decomposition of acetylene with CoFe2O4 as precursor. The as-prepared CoFe@C was characterized by X-ray powder diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, transmission electron microscopy, and thermogravimetric analysis. The results demonstrate that the carbon shell in CoFe@C has a poor crystallization with a thickness about 5-30 nm and a content approximately 48.5 wt.%. Due to a good combination between intrinsic magnetic properties and high-electrical conductivity, the CoFe@C exhibits not only excellent absorption intensity but also wide frequency bandwidth. The minimum RL value of CoFe@C can reach - 44 dB at a thickness of 4.0 mm, and RL values below - 10 dB is up to 4.3 GHz at a thickness of 2.5 mm. The present CoFe@C may be a potential candidate for microwave absorption application.

Hierarchical calibration and validation framework of bench-scale computational fluid dynamics simulations for solvent-based carbon capture. Part 2: Chemical absorption across a wetted wall column: Original Research Article: Hierarchical calibration and validation framework of bench-scale computational fluid dynamics simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Chao; Xu, Zhijie; Lai, Kevin

Part 1 of this paper presents a numerical model for non-reactive physical mass transfer across a wetted wall column (WWC). In Part 2, we improved the existing computational fluid dynamics (CFD) model to simulate chemical absorption occurring in a WWC as a bench-scale study of solvent-based carbon dioxide (CO2) capture. To generate data for WWC model validation, CO2 mass transfer across a monoethanolamine (MEA) solvent was first measured on a WWC experimental apparatus. The numerical model developed in this work can account for both chemical absorption and desorption of CO2 in MEA. In addition, the overall mass transfer coefficient predictedmore » using traditional/empirical correlations is conducted and compared with CFD prediction results for both steady and wavy falling films. A Bayesian statistical calibration algorithm is adopted to calibrate the reaction rate constants in chemical absorption/desorption of CO2 across a falling film of MEA. The posterior distributions of the two transport properties, i.e., Henry's constant and gas diffusivity in the non-reacting nitrous oxide (N2O)/MEA system obtained from Part 1 of this study, serves as priors for the calibration of CO2 reaction rate constants after using the N2O/CO2 analogy method. The calibrated model can be used to predict the CO2 mass transfer in a WWC for a wider range of operating conditions.« less

Hierarchical calibration and validation framework of bench-scale computational fluid dynamics simulations for solvent-based carbon capture. Part 2: Chemical absorption across a wetted wall column: Original Research Article: Hierarchical calibration and validation framework of bench-scale computational fluid dynamics simulations

DOE PAGES

Wang, Chao; Xu, Zhijie; Lai, Kevin; ...

2017-10-24

Part 1 of this paper presents a numerical model for non-reactive physical mass transfer across a wetted wall column (WWC). In Part 2, we improved the existing computational fluid dynamics (CFD) model to simulate chemical absorption occurring in a WWC as a bench-scale study of solvent-based carbon dioxide (CO2) capture. To generate data for WWC model validation, CO2 mass transfer across a monoethanolamine (MEA) solvent was first measured on a WWC experimental apparatus. The numerical model developed in this work can account for both chemical absorption and desorption of CO2 in MEA. In addition, the overall mass transfer coefficient predictedmore » using traditional/empirical correlations is conducted and compared with CFD prediction results for both steady and wavy falling films. A Bayesian statistical calibration algorithm is adopted to calibrate the reaction rate constants in chemical absorption/desorption of CO2 across a falling film of MEA. The posterior distributions of the two transport properties, i.e., Henry's constant and gas diffusivity in the non-reacting nitrous oxide (N2O)/MEA system obtained from Part 1 of this study, serves as priors for the calibration of CO2 reaction rate constants after using the N2O/CO2 analogy method. The calibrated model can be used to predict the CO2 mass transfer in a WWC for a wider range of operating conditions.« less

Imaging diffuse clouds: bright and dark gas mapped in CO

NASA Astrophysics Data System (ADS)

Liszt, H. S.; Pety, J.

2012-05-01

Aims: We wish to relate the degree scale structure of galactic diffuse clouds to sub-arcsecond atomic and molecular absorption spectra obtained against extragalactic continuum background sources. Methods: We used the ARO 12 m telescope to map J = 1-0 CO emission at 1' resolution over 30' fields around the positions of 11 background sources occulted by 20 molecular absorption line components, of which 11 had CO emission counterparts. We compared maps of CO emission to sub-arcsec atomic and molecular absorption spectra and to the large-scale distribution of interstellar reddening. Results: 1) The same clouds, identified by their velocity, were seen in absorption and emission and atomic and molecular phases, not necessarily in the same direction. Sub-arcsecond absorption spectra are a preview of what is seen in CO emission away from the continuum. 2) The CO emission structure was amorphous in 9 cases, quasi-periodic or wave-like around B0528+134 and tangled and filamentary around BL Lac. 3) Strong emission, typically 4-5 K at EB - V ≤ 0.15 mag and up to 10-12 K at EB - V ≲ 0.3 mag was found, much brighter than toward the background targets. Typical covering factors of individual features at the 1 K km s-1 level were 20%. 4) CO-H2 conversion factors as much as 4-5 times below the mean value N(H2)/WCO = 2 × 1020 H2 cm-2 (K km s-1)-1 are required to explain the luminosity of CO emission at/above the level of 1 K km s-1. Small conversion factors and sharp variability of the conversion factor on arcminute scales are due primarily to CO chemistry and need not represent unresolved variations in reddening or total column density. Conclusions: Like Fermi and Planck we see some gas that is dark in CO and other gas in which CO is overluminous per H2. A standard CO-H2 conversion factor applies overall owing to balance between the luminosities per H2 and surface covering factors of bright and dark CO, but with wide variations between sightlines and across the faces of individual clouds. Based on observations obtained with the ARO Kitt Peak 12 m telescope.Appendices are available in electronic form at http://www.aanda.org

Temporal correlation measurements of pulsed dual CO2 lidar returns. [for atmospheric pollution detection

NASA Technical Reports Server (NTRS)

Menyuk, N.; Killinger, D. K.

1981-01-01

A pulsed dual-laser direct-detection differential-absorption lidar DIAL system, operating near 10.6 microns, is used to measure the temporal correlation and statistical properties of backscattered returns from specular and diffuse topographic targets. Results show that atmospheric-turbulence fluctuations can effectively be frozen for pulse separation times on the order of 1-3 msec or less. The diffuse target returns, however, yielded a much lower correlation than that obtained with the specular targets; this being due to uncorrelated system noise effects and different statistics for the two types of target returns.

Laser-based measurements of pressure broadening and pressure shift coefficients of combustion-relevant absorption lines in the near-infrared region

NASA Astrophysics Data System (ADS)

Bürkle, Sebastian; Walter, Nicole; Wagner, Steven

2018-06-01

A set of high-resolution absorption spectrometers based on TDLAS was used to determine the impact of combustion-relevant gases on the pressure shift and broadening of H2O, CO2, C2H2 and CH4 absorption lines in the near-infrared spectral region. In particular, self- and foreign-broadening coefficients induced by CO2, N2, O2, air, C2H2 and CH4 were measured. The absorption lines under investigation are suitable to measure the respective species in typical combustion environments via laser absorption spectroscopy. Additionally, species-dependent self- and foreign-induced pressure shift coefficients were measured and compared to the literature. The experiments were performed in two specifically designed absorption cells over a wide pressure range from 5 to 180 kPa. Different sources of uncertainty were identified and quantified to achieve relative measurement uncertainties of 0.7-1.5% for broadening coefficients and 0.6-1.6% for pressure shift coefficients.

Hybridized orbital states in spin-orbit coupled 3 d -5 d double perovskites studied by x-ray absorption spectroscopy

NASA Astrophysics Data System (ADS)

Lee, Min-Cheol; Lee, Sanghyun; Won, C. J.; Lee, K. D.; Hur, N.; Chen, Jeng-Lung; Cho, Deok-Yong; Noh, T. W.

2018-03-01

We investigated the orbital hybridization mechanism in 3 d -5 d double perovskites (DPs) of La2CoIrO6 and La2CoPtO6 using x-ray absorption spectroscopy. It is clearly evidenced by O K -edge and Co K -edge x-ray absorption spectra that the Co 3 d orbitals hybridize not only with the half-filled Ir/Pt jeff states but also with the fully empty (unpolarized) Ir/Pt eg states in both DPs. The Co 3 d eg-Ir 5 d eg hybridization cannot contribute to the ferrimagnetic long-range order in La2CoIrO6 established by spin-selective Co 3 d t2 g-Ir 5 d jeff hybridization through the intermediate oxygen p state but could serve as an origin of paramagnetism. The strengths of such orbital hybridizations were found to be almost invariant to temperature, even far above the Curie temperature, implying persistent paramagnetism against the antiferromagnetic ordering in the spin-orbit entangled 3 d -5 d DPs.

Advances in High Energy Solid-State 2-micron Laser Transmitter Development for Ground and Airborne Wind and CO2 Measurements

NASA Technical Reports Server (NTRS)

Singh, Upendra N.; Yu, Jirong; Petros, Mulugeta; Chen, Songsheng; Kavaya, Michael J.; Trieu, Bo; Bai, Yingxin; Petzar, Paul; Modlin, Edward A.; Koch, Grady;

Enrichment process of biogas using simultaneous Absorption - Adsorption methods

NASA Astrophysics Data System (ADS)

Kusrini, Eny; Lukita, Maya; Gozan, Misri; Susanto, Bambang Heru; Nasution, Dedy Alharis; Rahman, Arif; Gunawan, Cindy

2017-03-01

Removal of CO2 in biogas is an essential methods to the purification and upgrading of biogas. Natural Clinoptilolite zeolites were evaluated as sorbents for purification of biogas that produced from palm oil mill effluent (POME) by anerobic-digestion method. The absorption and adsorption experiments were conducted in a fixed-bed two column adsorption unit by simultaneous absorption-adsorption method. The Ca(OH)2 solution with concentration of 0.062 M was used as absorption method. Sorbent for removal of CO2 in biogas have been prepared by modifying of Clinoptilolite zeolites with an acid (HCl, 2M) and alkaline (NaOH, 2M), calcined at 450°C and then coated using chitosan (0.5 w/v%) in order to increase their adsorption capacity. The removal of CO2 in biogas was achieved about ˜83% using 2.5 g of sorbent zeolite (2M)/chitosan dosage for each column, breakthrough time of 30 min, and flow rate of 100 mL/min. Clinoptilolite zeolites with modifications of an acid-alkaline and chitosan (zeolite (2M)/chitosan) are promising sorbents due to the amine groups from chitosan and high surface-volume ratio are one of important factors in a simultaneous absorption-adsorption method.

Hybrid Membrane/Absorption Process for Post-combustion CO2 Capture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Shiguang; Shou, S.; Pyrzynski, Travis

2013-12-31

This report summarizes scientific/technical progress made for bench-scale membrane contactor technology for post-combustion CO2 capture from DOE Contract No. DE-FE-0004787. Budget Period 1 (BP1) membrane absorber, Budget Period 2 (BP2) membrane desorber and Budget Period 3 (BP3) integrated system and field testing studies have been completed successfully and met or exceeded the technical targets (≥ 90% CO2 removal and CO2 purity of 97% in one membrane stage). Significant breakthroughs are summarized below: BP1 research: The feasibility of utilizing the poly (ether ether ketone), PEEK, based hollow fiber contractor (HFC) in combination with chemical solvents to separate and capture at leastmore » 90% of the CO2 from simulated flue gases has been successfully established. Excellent progress has been made as we have achieved the BP1 goal: ≥ 1,000 membrane intrinsic CO2 permeance, ≥ 90% CO2 removal in one stage, ≤ 2 psi gas side pressure drop, and ≥ 1 (sec)-1 mass transfer coefficient. Initial test results also show that the CO2 capture performance, using activated Methyl Diethanol Amine (aMDEA) solvent, was not affected by flue gas contaminants O2 (~3%), NO2 (66 ppmv), and SO2 (145 ppmv). BP2 research: The feasibility of utilizing the PEEK HFC for CO2-loaded solvent regeneration has been successfully established High CO2 stripping flux, one order of magnitude higher than CO2 absorption flux, have been achieved. Refined economic evaluation based on BP1 membrane absorber and BP2 membrane desorber laboratory test data indicate that the CO2 capture costs are 36% lower than DOE’s benchmark amine absorption technology. BP3 research: A bench-scale system utilizing a membrane absorber and desorber was integrated into a continuous CO2 capture process using contactors containing 10 to 20 ft2 of membrane area. The integrated process operation was stable through a 100-hour laboratory test, utilizing a simulated flue gas stream. Greater than 90% CO2 capture combined with 97% CO2 product purity was achieved throughout the test. Membrane contactor modules have been scaled from bench scale 2-inch diameter by 12-inch long (20 ft2 membrane surface area) modules to 4-inch diameter by 60-inch long pilot scale modules (165 ft2 membrane surface area). Pilot scale modules were tested in an integrated absorption/regeneration system for CO2 capture field tests at a coal-fired power plant (Midwest Generation’s Will County Station located in Romeoville, IL). Absorption and regeneration contactors were constructed utilizing high performance super-hydrophobic, nano-porous PEEK membranes with CO2 gas permeance of 2,000 GPU and a 1,000 GPU, respectively. Field tests using aMDEA solvent achieved greater than 90% CO2 removal in a single stage. The absorption mass transfer coefficient was 1.2 (sec)-1, exceeding the initial target of 1.0 (sec)-1. This mass transfer coefficient is over one order of magnitude greater than that of conventional gas/liquid contacting equipment. The economic evaluation based on field tests data indicates that the CO2 capture cost associated with membrane contactor technology is $54.69 (Yr 2011$)/tonne of CO2 captured when using aMDEA as a solvent. It is projected that the DOE’s 2025 cost goal of $40 (Yr 2011$)/tonne of CO2 captured can be met by decreasing membrane module cost and by utilizing advanced CO2 capture solvents. In the second stage of the field test, an advanced solvent, Hitachi’s H3-1 was utilized. The use of H3-1 solvent increased mass transfer coefficient by 17% as compared to aMDEA solvent. The high mass transfer coefficient of H3-1 solvent combined with much more favorable solvent regeneration requirements, indicate that the projected savings achievable with membrane contactor process can be further improved. H3-1 solvent will be used in the next pilot-scale development phase. The integrated absorption/regeneration process design and high performance membrane contactors developed in the current bench-scale program will be used as the base technology for future pilot-scale development.« less

Atmospheric boundary layer CO2 remote sensing with a direct detection LIDAR instrument based on a widely tunable optical parametric source.

PubMed

Cadiou, Erwan; Mammez, Dominique; Dherbecourt, Jean-Baptiste; Gorju, Guillaume; Pelon, Jacques; Melkonian, Jean-Michel; Godard, Antoine; Raybaut, Myriam

2017-10-15

We report on the capability of a direct detection differential absorption lidar (DIAL) for range resolved and integrated path (IPDIAL) remote sensing of CO 2 in the atmospheric boundary layer (ABL). The laser source is an amplified nested cavity optical parametric oscillator (NesCOPO) emitting approximately 8 mJ at the two measurement wavelengths selected near 2050 nm. Direct detection atmospheric measurements are taken from the ground using a 30 Hz frequency switching between emitted wavelengths. Results show that comparable precision measurements are achieved in DIAL and IPDIAL modes (not better than a few ppm) on high SNR targets such as near range ABL aerosol and clouds, respectively. Instrumental limitations are analyzed and degradation due to cloud scattering variability is discussed to explain observed DIAL and IPDIAL limitations.

Effect of interferogram smearing on atmospheric limb sounding by Fourier transform spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, J.H.

1982-04-15

A method is presented for analyzing an absorption spectrum obtained from the interferogram measured by an interferometer operated in the solar occultation mode. In this mode the complete interferogram is smeared with various components of individual interferograms generated by rays passing through different tangent altitudes. It is shown that the effective tangent altitude of the spectrum is the altitude at which the center fringe of the interferogram is recorded and that the other components of the interferogram only define the instrument line shape. The interferogram smearing effectively creates strong sidelobes on absorption lines so that a strong apodization on themore » interferogram is recommended for the solar occultation experiment. These concepts applied to retrieve pressure and temperature simultaneously from stratospheric absorption spectra in the CO/sub 2/ 4.3-..mu..m band obtained by a balloon-borne interferometer in 1976 over Palestine, Tex. Included in the analysis of the CO/sub 2/ 4.3-..mu..m band are the continuum absorptions by the pressure-induced N/sub 2/ fundamental band and by far wings of the CO/sub 2/ v/sub 3/ band. The CO/sub 2/ absorption line is corrected by a sub-Lorentzian function. Excellent agreement is found between the observed and simulated spectra.« less

Measurements of sulfur compounds in CO 2 by diode laser atomic absorption spectrometry

NASA Astrophysics Data System (ADS)

Franzke, J.; Stancu, D. G.; Niemax, K.

2003-07-01

Two simple methods for the analysis of the total concentration of sulfur in CO 2 by diode laser atomic absorption spectrometry of excited, metastable sulfur atoms in a direct current discharge are presented. In the first method, the CO 2 sample gas is mixed with the plasma gas (Ar or He) while the second is based on reproducible measurements of the sulfur released from the walls in a helium discharge after being deposited as a result of operating the discharge in pure CO 2 sample gas. The detection limits obtained satisfy the requirements for the control of sulfur compounds in CO 2 used in the food and beverage industry.

FTIR microspectroscopy and SIMS study of water-poor cordierite from El Hoyazo, Spain: Application to mineral and melt devolatilization

NASA Astrophysics Data System (ADS)

Della Ventura, Giancarlo; Bellatreccia, Fabio; Cesare, Bernardo; Harley, Simon; Piccinini, Massimo

2009-12-01

This paper reports the microchemical and microspectroscopic FTIR study of cordierite from a partially melted graphite-bearing granulitic enclave within the dacitic lava dome of El Hoyazo (SE Spain). Optically transparent single-crystals, hand picked from the rock, were oriented using X-ray diffraction and studied by Fourier-transform infrared (FTIR). Single-crystal FTIR spectroscopy shows that the examined cordierite is CO 2-rich and almost H 2O-free. Two weak and sharp peaks are observed at 3708 and 3595 cm - 1 , respectively, which are strongly polarised for E // a. These peaks are assigned to combination modes of CO 2. Very weak bands due to H 2O molecules oriented with the H…H vector // c (type I water) are occasionally observed in certain zones of the grains, associated with absorptions due to hydrated inclusions of alteration products. The very intense bands observed in the 2600-2000 cm - 1 region are assigned to CO 2 molecules oriented // a; the spectra also show the presence of 13C and 18O, and weak amounts of CO in the sample. Microspectrometric mapping shows that the distribution of C is relatively homogeneous, whereas that of H 2O is complicated by a very broad absorption extending from 3700 to 3100 cm - 1 . High-resolution FTIR imaging, done using a focal-plane array of detectors, shows that this broad absorption is associated with microfractures. SIMS analyses give an average concentration of H 2O = 0.033 ± 0.007 wt.% and CO 2 = 0.21 ± 0.07 wt.%. On the basis of these data, molar absorption coefficients can be calibrated for CO 2: ɛiCO2 (integrated) = 11,000 ± 4000 l/(mol cm - 2 ) and ɛlCO2 (linear) = 800 ± 250 l/(mol cm - 1 ). Due to the extremely low amount of H 2O and its inhomogeneous distribution, calibration of absorption ɛH2O coefficients is unreliable. The very low H 2O contents in the El Hoyazo cordierite indicate continued mineral-melt volatile exchange during decompression from ˜ 5 kbar to significantly shallower levels.

Multi-species laser absorption sensors for in situ monitoring of syngas composition

NASA Astrophysics Data System (ADS)

Sur, Ritobrata; Sun, Kai; Jeffries, Jay B.; Hanson, Ronald K.

2014-04-01

Tunable diode laser absorption spectroscopy sensors for detection of CO, CO2, CH4 and H2O at elevated pressures in mixtures of synthesis gas (syngas: products of coal and/or biomass gasification) were developed and tested. Wavelength modulation spectroscopy (WMS) with 1f-normalized 2f detection was employed. Fiber-coupled DFB diode lasers operating at 2325, 2017, 2290 and 1352 nm were used for simultaneously measuring CO, CO2, CH4 and H2O, respectively. Criteria for the selection of transitions were developed, and transitions were selected to optimize the signal and minimize interference from other species. For quantitative WMS measurements, the collision-broadening coefficients of the selected transitions were determined for collisions with possible syngas components, namely CO, CO2, CH4, H2O, N2 and H2. Sample measurements were performed for each species in gas cells at a temperature of 25 °C up to pressures of 20 atm. To validate the sensor performance, the composition of synthetic syngas was determined by the absorption sensor and compared with the known values. A method of estimating the lower heating value and Wobbe index of the syngas mixture from these measurements was also demonstrated.

Kinetic study of carbon dioxide absorption into glycine promoted diethanolamine (DEA)

NASA Astrophysics Data System (ADS)

Pudjiastuti, Lily; Susianto, Altway, Ali; IC, Maria Hestia; Arsi, Kartika

2015-12-01

In industry, especially petrochemical, oil and natural gas industry, required separation process of CO2 gas which is a corrosive gas (acid gas). This characteristic can damage the plant utility and piping systems as well as reducing the caloric value of natural gas. Corrosive characteristic of CO2 will appear in areas where there is a decrease in temperature and pressure, such as at the elbow pipe, tubing, cooler and injector turbine. From disadvantages as described above, then it is important to do separation process in the CO2 gas stream, one of the method for remove CO2 from the gas stream is reactive absorption using alkanolamine based solution with promotor. Therefore, this study is done to determine the kinetics constant of CO2 absorption in diethanolamine (DEA) solution using a glycine promoter. Glycine is chosen as a promoter because glycine is a primary amine compound which is reactive, moreover, glycine has resistance to high temperatures so it will not easy to degradable and suitable for application in industry. The method used in this study is absorption using laboratory scale wetted wall column equipment at atmospheric of pressure. This study will to provide the reaction kinetics data information in order to optimize the separation process of CO2 in the industrialized world. The experimental results show that rising temperatures from 303,15 - 328,15 K and the increase of concentration of glycine from 1% - 3% weight will increase the absorption rate of carbon dioxide in DEA promoted with glycine by 24,2% and 59,764% respectively, also the reaction kinetic constant is 1.419 × 1012 exp (-3634/T) (m3/kmol.s). This result show that the addition of glycine as a promoter can increase absorption rate of carbon dioxide in diethanolamine solution and cover the weaknesses of diethanolamine solution.

VUV-absorption cross section of carbon dioxide from 150 to 800 K and applications to warm exoplanetary atmospheres

NASA Astrophysics Data System (ADS)

Venot, O.; Bénilan, Y.; Fray, N.; Gazeau, M.-C.; Lefèvre, F.; Es-sebbar, Et.; Hébrard, E.; Schwell, M.; Bahrini, C.; Montmessin, F.; Lefèvre, M.; Waldmann, I. P.

2018-01-01

Context. Most exoplanets detected so far have atmospheric temperatures significantly higher than 300 K. Often close to their star, they receive an intense UV photons flux that triggers important photodissociation processes. The temperature dependency of vacuum ultraviolet (VUV) absorption cross sections are poorly known, leading to an undefined uncertainty in atmospheric models. Similarly, data measured at low temperatures similar to those of the high atmosphere of Mars, Venus, and Titan are often lacking. Aims: Our aim is to quantify the temperature dependency of the VUV absorption cross sections of important molecules in planetary atmospheres. We want to provide high-resolution data at temperatures prevailing in these media, and a simple parameterisation of the absorption in order to simplify its use in photochemical models. This study focuses on carbon dioxide (CO2). Methods: We performed experimental measurements of CO2 absorption cross sections with synchrotron radiation for the wavelength range (115-200 nm). For longer wavelengths (195-230 nm), we used a deuterium lamp and a 1.5 m Jobin-Yvon spectrometer. We used these data in our one-dimensional (1D) thermo-photochemical model in order to study their impact on the predicted atmospheric compositions. Results: The VUV absorption cross section of CO2 increases with the temperature. The absorption we measured at 150 K seems to be close to the absorption of CO2 in the fundamental ground state. The absorption cross section can be separated into two parts: a continuum and a fine structure superimposed on the continuum. The variation in the continuum of absorption can be represented by the sum of three Gaussian functions. Using data at high temperature in thermo-photochemical models significantly modifies the abundance and the photodissociation rates of many species in addition to CO2, such as methane and ammonia. These deviations have an impact on synthetic transmission spectra, leading to variations of up to 5 ppm. Conclusions: We present a full set of high-resolution (Δλ = 0.03 nm) absorption cross sections of CO2 from 115 to 230 nm for temperatures ranging from 150 to 800 K. A parameterisation allows us to calculate the continuum of absorption in this wavelength range. Extrapolation at higher temperature has not been validated experimentally and therefore should be used with caution. Similar studies on other major species are necessary to improve our understanding of planetary atmospheres. The data presented in Fig. 1 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/609/A34

Atmospheric influences on infrared-laser signals used for occultation measurements between Low Earth Orbit satellites

NASA Astrophysics Data System (ADS)

Schweitzer, S.; Kirchengast, G.; Proschek, V.

2011-10-01

LEO-LEO infrared-laser occultation (LIO) is a new occultation technique between Low Earth Orbit (LEO) satellites, which applies signals in the short wave infrared spectral range (SWIR) within 2 μm to 2.5 μm. It is part of the LEO-LEO microwave and infrared-laser occultation (LMIO) method that enables to retrieve thermodynamic profiles (pressure, temperature, humidity) and altitude levels from microwave signals and profiles of greenhouse gases and further variables such as line-of-sight wind speed from simultaneously measured LIO signals. Due to the novelty of the LMIO method, detailed knowledge of atmospheric influences on LIO signals and of their suitability for accurate trace species retrieval did not yet exist. Here we discuss these influences, assessing effects from refraction, trace species absorption, aerosol extinction and Rayleigh scattering in detail, and addressing clouds, turbulence, wind, scattered solar radiation and terrestrial thermal radiation as well. We show that the influence of refractive defocusing, foreign species absorption, aerosols and turbulence is observable, but can be rendered small to negligible by use of the differential transmission principle with a close frequency spacing of LIO absorption and reference signals within 0.5%. The influences of Rayleigh scattering and terrestrial thermal radiation are found negligible. Cloud-scattered solar radiation can be observable under bright-day conditions, but this influence can be made negligible by a close time spacing (within 5 ms) of interleaved laser-pulse and background signals. Cloud extinction loss generally blocks SWIR signals, except very thin or sub-visible cirrus clouds, which can be addressed by retrieving a cloud layering profile and exploiting it in the trace species retrieval. Wind can have a small influence on the trace species absorption, which can be made negligible by using a simultaneously retrieved or a moderately accurate background wind speed profile. We conclude that the set of SWIR channels proposed for implementing the LMIO method (Kirchengast and Schweitzer, 2011) provides adequate sensitivity to accurately retrieve eight trace species of key importance to climate and atmospheric chemistry (H2O, CO2, 13CO2, C18OO, CH4, N2O, O3, CO) in the upper troposphere/lower stratosphere region outside clouds under all atmospheric conditions. Two further species (HDO, H218O) can be retrieved in the upper troposphere.

PNNL Report on the Development of Bench-scale CFD Simulations for Gas Absorption across a Wetted Wall Column

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Chao; Xu, Zhijie; Lai, Canhai

This report is prepared for the demonstration of hierarchical prediction of carbon capture efficiency of a solvent-based absorption column. A computational fluid dynamics (CFD) model is first developed to simulate the core phenomena of solvent-based carbon capture, i.e., the CO2 physical absorption and chemical reaction, on a simplified geometry of wetted wall column (WWC) at bench scale. Aqueous solutions of ethanolamine (MEA) are commonly selected as a CO2 stream scrubbing liquid. CO2 is captured by both physical and chemical absorption using highly CO2 soluble and reactive solvent, MEA, during the scrubbing process. In order to provide confidence bound on themore » computational predictions of this complex engineering system, a hierarchical calibration and validation framework is proposed. The overall goal of this effort is to provide a mechanism-based predictive framework with confidence bound for overall mass transfer coefficient of the wetted wall column (WWC) with statistical analyses of the corresponding WWC experiments with increasing physical complexity.« less

Local 3d Electronic Structures of Co-Based Complexes with Medicinal Molecules Probed by Soft X-ray Absorption

NASA Astrophysics Data System (ADS)

Yamagami, Kohei; Fujiwara, Hidenori; Imada, Shin; Kadono, Toshiharu; Yamanaka, Keisuke; Muro, Takayuki; Tanaka, Arata; Itai, Takuma; Yoshinari, Nobuto; Konno, Takumi; Sekiyama, Akira

2017-07-01

We have examined the local 3d electronic structures of Co-Au multinuclear complexes with the medicinal molecules d-penicillaminate (d-pen) [Co{Au(PPh3)(d-pen)}2]ClO4 and [Co3{Au3(tdme)(d-pen)3}2] by Co L2,3-edge soft X-ray absorption (XAS) spectroscopy, where PPh3 denotes triphenylphosphine and tdme stands for 1,1,1-tris[(diphenylphosphino)methyl]ethane. The Co L2,3-edge XAS spectra indicate the localized ionic 3d electronic states in both materials. The experimental spectra are well explained by spectral simulation for a localized Co ion under ligand fields with the full multiplet theory, which verifies that the ions are in the low-spin Co3+ state in the former compound and in the high-spin Co2+ state in the latter.

315mJ, 2-micrometers Double-Pulsed Coherent Differential Absorption Lidar Transmitter for Atmospheric CO2 Sensing

NASA Technical Reports Server (NTRS)

Yu, Jirong; Trieu, Bo; Bai, Yingxin; Koch, Grady; Chen, Songsheng; Petzar, Paul; Singh, Upendra N.; Kavaya, Michael J.; Beyon, Jeffrey

2010-01-01

The design of a double pulsed, injection seeded, 2-micrometer compact coherent Differential absorption Lidar (DIAL) transmitter for CO2 sensing is presented. This system is hardened for ground and airborne applications. The design architecture includes three continuous wave lasers which provide controlled on and off line seeding, injection seeded power oscillator and a single amplifier operating in double pass configuration. As the derivative a coherent Doppler wind lidar, this instrument has the added benefit of providing wind information. The active laser material used for this application is a Ho: Tm:YLF crystal operates at the eye-safe wavelength. The 3-meter long folded ring resonator produces energy of 130-mJ (90/40) with a temporal pulse length around 220 nanoseconds and 530 nanosecond pulses for on and off lines respectively. The separation between the two pulses is on the order of 200 microseconds. The line width is in the order of 2.5MHz and the beam quality has an M(sup 2) of 1.1 times diffraction limited beam. A final output energy for a pair of both on and off pulses as high as 315 mJ (190/125) at a repetition rate of 10 Hz is achieved. The operating temperature is set around 20 C for the pump diode lasers and 10 C for the rod. Since the laser design has to meet high-energy as well as high beam quality requirements, close attention is paid to the laser head design to avoid thermal distortion in the rod. A side-pumped configuration is used and heat is removed uniformly by passing coolant through a tube slightly larger than the rod to reduce thermal gradient. This paper also discusses the advantage of using a long upper laser level life time laser crystal for DIAL application. In addition issues related to injection seeding with two different frequencies to achieve a transform limited line width will be presented.

Study on the effects of Ga-2N high co-doping and preferred orientation on the stability, bandgap and absorption spectrum of ZnO

NASA Astrophysics Data System (ADS)

Hou, Qing-Yu; Li, Wen-Cai; Qu, Ling-Feng; Zhao, Chun-Wang

2017-06-01

Currently, the stability and visible light properties of Ga-2N co-doped ZnO systems have been studied extensively by experimental analysis and theoretical calculations. However, previous theoretical calculations arbitrarily assigned Ga- and 2N-doped sites in ZnO. In addition, the most stable and possible doping orientations of doped systems have not been fully and systematically considered. Therefore, in this paper, the electron structure and absorption spectra of the unit cells of doped and pure systems were calculated by first-principles plane-wave ultrasoft pseudopotential with the GGA+U method. Calculations were performed for pure ZnO, Ga-2N supercells heavily co-doped with Zn1-xGaxO1-yNy (x = 0.03125 - 0.0625, y = 0.0625 - 0.125) under different co-doping orientations and conditions, and the Zn16GaN2O14 interstitial model. The results indicated that under different orientations and constant Ga-2N co-doping concentrations, the systems co-doped with Ga-N atoms vertically oriented to the c-axis and with another N atom located in the nearest-neighboring site exhibited higher stability over the others, thus lowering formation energy and facilitating doping. Moreover, Ga-interstitial- and 2N-co-doped ZnO systems easily formed chemical compounds. Increasing co-doping concentration while the co-doping method remained constant decreased doped system volume and lowered formation energies. Meantime, co-doped systems were more stable and doping was facilitated. The bandgap was also narrower and red shifting of the absorption spectrum was more significant. These results agreed with previously reported experimental results. In addition, the absorption spectra of Ga-interstitial- and 2N-co-doped ZnO both blue shifted in the UV region compared with that of the pure ZnO system.

Carbonic anhydrase-facilitated CO2 absorption with polyacrylamide buffering bead capture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dilmore, Robert; Griffith, Craid; Liu, Zhu

2009-07-01

A novel CO2 separation concept is described wherein the enzyme carbonic anhydrase (CA) is used to increase the overall rate Of CO2 absorption after which hydrated CO2 reacts with regenerable amine-bearing polyacrylamide buffering beads (PABB). Following saturation of the material's immobilized tertiary amines, CA-bearing carrier water is separated and recycled to the absorption stage while CO2-loaded material is thermally regenerated. Process application of this concept would involve operation of two or more columns in parallel with thermal regeneration with low-pressure steam taking place after the capacity of a column of amine-bearing polymeric material was exceeded. PABB CO2- bearing capacity wasmore » evaluated by thermogravimetric analysis (TGA) for beads of three acrylamido buffering monomer ingredient concentrations: 0 mol/kg bead, 0.857 mol/kg bead, and 2 mol/kg bead. TGA results demonstrate that CO2- bearing capacity increases with increasing PABB buffering concentration and that up to 78% of the theoretical CO2- bearing capacity was realized in prepared PABB samples (0.857 mol/kg recipe). The highest observed CO2-bearing capacity of PABB was 1.37 mol of CO2 per kg dry bead. TGA was also used to assess the regenerability Of CO2-loaded PABB. Preliminary results suggest that CO2 is partially driven from PABB samples at temperatures as low as 55 degrees C, with complete regeneration occurring at 100 degrees C. Other physical characteristics of PABB are discussed. In addition, the effectiveness of bovine carbonic anhydrase for the catalysis Of CO2 dissolution is evaluated. Potential benefits and drawbacks of the proposed process are discussed. Published by Elsevier Ltd.« less

Pseudorandom Noise Code-Based Technique for Thin Cloud Discrimination with CO2 and O2 Absorption Measurements

NASA Technical Reports Server (NTRS)

Campbell, Joel F.; Prasad, Narasimha S.; Flood, Michael A.

2011-01-01

NASA Langley Research Center is working on a continuous wave (CW) laser based remote sensing scheme for the detection of CO2 and O2 from space based platforms suitable for ACTIVE SENSING OF CO2 EMISSIONS OVER NIGHTS, DAYS, AND SEASONS (ASCENDS) mission. ASCENDS is a future space-based mission to determine the global distribution of sources and sinks of atmospheric carbon dioxide (CO2). A unique, multi-frequency, intensity modulated CW (IMCW) laser absorption spectrometer (LAS) operating at 1.57 micron for CO2 sensing has been developed. Effective aerosol and cloud discrimination techniques are being investigated in order to determine concentration values with accuracies less than 0.3%. In this paper, we discuss the demonstration of a pseudo noise (PN) code based technique for cloud and aerosol discrimination applications. The possibility of using maximum length (ML)-sequences for range and absorption measurements is investigated. A simple model for accomplishing this objective is formulated, Proof-of-concept experiments carried out using SONAR based LIDAR simulator that was built using simple audio hardware provided promising results for extension into optical wavelengths.

On the size dependence of the scattering greenhouse effect of CO2 ice particles

NASA Astrophysics Data System (ADS)

Kitzmann, D.; Patzer, A. B. C.; Rauer, H.

2011-10-01

In this contribution we study the potential greenhouse effect due to scattering of CO2 ice clouds for atmospheric conditions of terrestrial extrasolar planets. Therefore, we calculate the scattering and absorption properties of CO2 ice particles using Mie theory for assumed particle size distributions with different effective radii and particle densities to determine the scattering and absorption characteristics of such clouds. Implications especially in view of a potential greenhouse warming of the planetary surface are discussed.

Improving atmospheric CO2 retrievals using line mixing and speed-dependence when fitting high-resolution ground-based solar spectra

NASA Astrophysics Data System (ADS)

Mendonca, J.; Strong, K.; Toon, G. C.; Wunch, D.; Sung, K.; Deutscher, N. M.; Griffith, D. W. T.; Franklin, J. E.

2016-05-01

A quadratic speed-dependent Voigt spectral line shape with line mixing (qSDV + LM) has been included in atmospheric trace-gas retrievals to improve the accuracy of the calculated CO2 absorption coefficients. CO2 laboratory spectra were used to validate absorption coefficient calculations for three bands: the strong 20013 ← 00001 band centered at 4850 cm-1, and the weak 30013 ← 00001 and 30012 ← 00001 bands centered at 6220 cm-1 and 6340 cm-1 respectively, and referred to below as bands 1 and 2. Several different line lists were tested. Laboratory spectra were best reproduced for the strong CO2 band when using HITRAN 2008 spectroscopic data with air-broadened widths divided by 0.985, self-broadened widths divided by 0.978, line mixing coefficients calculated using the exponential power gap (EPG) law, and a speed-dependent parameter of 0.11 used for all lines. For the weak CO2 bands, laboratory spectra were best reproduced using spectroscopic parameters from the studies by Devi et al. in 2007 coupled with line mixing coefficients calculated using the EPG law. A total of 132,598 high-resolution ground-based solar absorption spectra were fitted using qSDV + LM to calculate CO2 absorption coefficients and compared to fits that used the Voigt line shape. For the strong CO2 band, the average root mean square (RMS) residual is 0.49 ± 0.22% when using qSDV + LM to calculate the absorption coefficients. This is an improvement over the results with the Voigt line shape, which had an average RMS residual of 0.60 ± 0.21%. When using the qSDV + LM to fit the two weak CO2 bands, the average RMS residual is 0.47 ± 0.19% and 0.51 ± 0.20% for bands 1 and 2, respectively. These values are identical to those obtained with the Voigt line shape. Finally, we find that using the qSDV + LM decreases the airmass dependence of the column averaged dry air mole fraction of CO2 retrieved from the strong and both weak CO2 bands when compared to the retrievals obtained using the Voigt line shape.

High CO2 absorption capacity by chemisorption at cations and anions in choline-based ionic liquids.

PubMed

Bhattacharyya, Shubhankar; Filippov, Andrei; Shah, Faiz Ullah

2017-11-29

The effect of CO 2 absorption on the aromaticity and hydrogen bonding in ionic liquids is investigated. Five different ionic liquids with choline based cations and aprotic N-heterocyclic anions were synthesized. Purity and structures of the synthesized ionic liquids were characterized by 1 H and 13 C NMR spectroscopy. CO 2 capture performance was studied at 20 °C and 40 °C under three different pressures (1, 3, 6 bar). The IL [N 1,1,6,2OH ][4-Triz] showed the highest CO 2 capture capacity (28.6 wt%, 1.57 mol of CO 2 per mol of the IL, 6.48 mol of CO 2 per kg of the ionic liquid) at 20 °C and 1 bar. The high CO 2 capture capacity of the [N 1,1,6,2OH ][4-Triz] IL is due to the formation of carbonic acid (-OCO 2 H) together with carbamate by participation of the -OH group of the [N 1,1,6,2OH ] + cation in the CO 2 capture process. The structure of the adduct formed by CO 2 reaction with the IL [N 1,1,6,2OH ][4-Triz] was probed by using IR, 13 C NMR and 1 H- 13 C HMBC NMR experiments utilizing 13 C labeled CO 2 gas. 1 H and 13 C PFG NMR studies were performed before and after CO 2 absorption to explore the effect of cation-anion structures on the microscopic ion dynamics in ILs. The ionic mobility was significantly increased after CO 2 reaction due to lowering of aromaticity in the case of ILs with aromatic N-heterocyclic anions.

Development of Multifunctional Active Film and Its Application in Modified Atmosphere Packaging of Shiitake Mushrooms.

PubMed

Wang, Hong Jiang; An, Duck Soon; Lee, Dong Sun

2016-09-01

Agar-based films with multiple functions (CO 2 absorption, water vapor absorption, and antimicrobial activity) were developed, tested for their properties, and then applied to the packaging of fresh shiitake mushrooms as an insert label. The films were cast from an agar-based aqueous solution containing a dissolving plasticizer (glycerol), a CO 2 absorbent (sodium carbonate [SC] alone or a combination of SC and sodium glycinate [SC-SG]), and a volatile antimicrobial agent (carvacrol [CRV]). The agar of the film matrix is designed to serve as a water vapor absorbent. The multifunctional films tended to have poor mechanical properties, with a hard texture and an opaque and yellowish color. The CO 2 absorbent, either SC alone or SC-SG, affected CRV retention and release along with the CO 2 and water vapor absorption behavior. Both films (SC-CRV and SC-SG-CRV films) showed good inhibitory effects against Pseudomonas fluorescens and Saccharomyces cerevisiae . SC-CRV film had a higher and faster CO 2 absorption property, higher retention and extended release of CRV, and lower and slower water vapor absorption and was assessed to be better suited for use in shiitake mushroom packaging. The packaging in which the SC-CRV film with an appropriate amount of CRV was used as an insert label was able to generate the desired atmosphere and less moisture condensation inside the package, producing the best preservation of quality in terms of mushroom color, firmness, flavor score, and microbial counts after 6 days of storage at 10°C. A tailored modified atmosphere packaging system using multifunctional film would be useful in the preservation of CO 2 -sensitive fresh commodities.

Differential optical absorption spectrometer for measurement of tropospheric pollutants

NASA Astrophysics Data System (ADS)

Evangelisti, F.; Baroncelli, A.; Bonasoni, P.; Giovanelli, G.; Ravegnani, F.

1995-05-01

Our institute has recently developed a differential optical absorption spectrometry system called the gas analyzer spectrometer correlating optical absorption differences (GASCOAD), which features as a detector a linear image sensor that uses an artificial light source for long-path tropospheric-pollution monitoring. The GASCOAD, its method of eliminating interference from background sky light, and subsequent spectral analysis are reported and discussed. The spectrometer was used from 7 to 22 February 1993 in Milan, a heavily polluted metropolitan area, to measure the concentrations of SO2, NO2, O3, and HNO2 averaged over a 1.7-km horizontal light path. The findings are reported and briefly discussed.

[Open-path online monitoring of ambient atmospheric CO2 based on laser absorption spectrum].

PubMed

He, Ying; Zhang, Yu-Jun; Kan, Rui-Feng; Xia, Hui; Geng, Hui; Ruan, Jun; Wang, Min; Cui, Xiao-Juan; Liu, Wen-Qing

2009-01-01

With the conjunction of tunable diode laser absorption spectroscopy technology (TDLAS) and the open long optical path technology, the system designing scheme of CO2 on-line monitoring based on near infrared tunable diode laser absorption spectroscopy technology was discussed in detail, and the instrument for large-range measurement was set up. By choosing the infrared absorption line of CO2 at 1.57 microm whose line strength is strong and suitable for measurement, the ambient atmospheric CO2 was measured continuously with a 30 s temporal resolution at an suburb site in the autumn of 2007. The diurnal atmospheric variations of CO2 and continuous monitoring results were presented. The results show that the variation in CO2 concentration has an obvious diurnal periodicity in suburb where the air is free of interference and contamination. The general characteristic of diurnal variation is that the concentration is low in the daytime and high at night, so it matches the photosynthesis trend. The instrument can detect gas concentration online with high resolution, high sensitivity, high precision, short response time and many other advantages, the monitoring requires no gas sampling, the calibration is easy, and the detection limit is about 4.2 x 10(-7). It has been proved that the system and measurement project are feasible, so it is an effective method for gas flux continuous online monitoring of large range in ecosystem based on TDLAS technology.

Hierarchical calibration and validation framework of bench-scale computational fluid dynamics simulations for solvent-based carbon capture. Part 2: Chemical absorption across a wetted wall column: Original Research Article: Hierarchical calibration and validation framework of bench-scale computational fluid dynamics simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Chao; Xu, Zhijie; Lai, Kevin

The first part of this paper (Part 1) presents a numerical model for non-reactive physical mass transfer across a wetted wall column (WWC). In Part 2, we improved the existing computational fluid dynamics (CFD) model to simulate chemical absorption occurring in a WWC as a bench-scale study of solvent-based carbon dioxide (CO2) capture. To generate data for WWC model validation, CO2 mass transfer across a monoethanolamine (MEA) solvent was first measured on a WWC experimental apparatus. The numerical model developed in this work has the ability to account for both chemical absorption and desorption of CO2 in MEA. In addition,more » the overall mass transfer coefficient predicted using traditional/empirical correlations is conducted and compared with CFD prediction results for both steady and wavy falling films. A Bayesian statistical calibration algorithm is adopted to calibrate the reaction rate constants in chemical absorption/desorption of CO2 across a falling film of MEA. The posterior distributions of the two transport properties, i.e., Henry’s constant and gas diffusivity in the non-reacting nitrous oxide (N2O)/MEA system obtained from Part 1 of this study, serves as priors for the calibration of CO2 reaction rate constants after using the N2O/CO2 analogy method. The calibrated model can be used to predict the CO2 mass transfer in a WWC for a wider range of operating conditions.« less

Hierarchical calibration and validation framework of bench-scale computational fluid dynamics simulations for solvent-based carbon capture. Part 2: Chemical absorption across a wetted wall column: Original Research Article: Hierarchical calibration and validation framework of bench-scale computational fluid dynamics simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Chao; Xu, Zhijie; Lai, Kevin

Part 1 of this paper presents a numerical model for non-reactive physical mass transfer across a wetted wall column (WWC). In Part 2, we improved the existing computational fluid dynamics (CFD) model to simulate chemical absorption occurring in a WWC as a bench-scale study of solvent-based carbon dioxide (CO 2) capture. In this study, to generate data for WWC model validation, CO 2 mass transfer across a monoethanolamine (MEA) solvent was first measured on a WWC experimental apparatus. The numerical model developed in this work can account for both chemical absorption and desorption of CO 2 in MEA. In addition,more » the overall mass transfer coefficient predicted using traditional/empirical correlations is conducted and compared with CFD prediction results for both steady and wavy falling films. A Bayesian statistical calibration algorithm is adopted to calibrate the reaction rate constants in chemical absorption/desorption of CO 2 across a falling film of MEA. The posterior distributions of the two transport properties, i.e., Henry's constant and gas diffusivity in the non-reacting nitrous oxide (N 2O)/MEA system obtained from Part 1 of this study, serves as priors for the calibration of CO 2 reaction rate constants after using the N 2O/CO 2 analogy method. Finally, the calibrated model can be used to predict the CO 2 mass transfer in a WWC for a wider range of operating conditions.« less

Hierarchical calibration and validation framework of bench-scale computational fluid dynamics simulations for solvent-based carbon capture. Part 2: Chemical absorption across a wetted wall column: Original Research Article: Hierarchical calibration and validation framework of bench-scale computational fluid dynamics simulations

DOE PAGES

Wang, Chao; Xu, Zhijie; Lai, Kevin; ...

2017-10-24

Part 1 of this paper presents a numerical model for non-reactive physical mass transfer across a wetted wall column (WWC). In Part 2, we improved the existing computational fluid dynamics (CFD) model to simulate chemical absorption occurring in a WWC as a bench-scale study of solvent-based carbon dioxide (CO 2) capture. In this study, to generate data for WWC model validation, CO 2 mass transfer across a monoethanolamine (MEA) solvent was first measured on a WWC experimental apparatus. The numerical model developed in this work can account for both chemical absorption and desorption of CO 2 in MEA. In addition,more » the overall mass transfer coefficient predicted using traditional/empirical correlations is conducted and compared with CFD prediction results for both steady and wavy falling films. A Bayesian statistical calibration algorithm is adopted to calibrate the reaction rate constants in chemical absorption/desorption of CO 2 across a falling film of MEA. The posterior distributions of the two transport properties, i.e., Henry's constant and gas diffusivity in the non-reacting nitrous oxide (N 2O)/MEA system obtained from Part 1 of this study, serves as priors for the calibration of CO 2 reaction rate constants after using the N 2O/CO 2 analogy method. Finally, the calibrated model can be used to predict the CO 2 mass transfer in a WWC for a wider range of operating conditions.« less

Microwave Absorption Properties of Co@C Nanofiber Composite for Normal and Oblique Incidence

NASA Astrophysics Data System (ADS)

Zhang, Junming; Wang, Peng; Chen, Yuanwei; Wang, Guowu; Wang, Dian; Qiao, Liang; Wang, Tao; Li, Fashen

2018-05-01

Co@C nanofibers have been prepared by an electrospinning technique. Uniform morphology of the nanofibers and good dispersion of the magnetic cobalt nanoparticles in the carbon fiber frame were confirmed by field-emission scanning electron microscopy and high-resolution transmission electron microscopy. The electromagnetic parameters of a composite absorber composed of Co@C nanofibers/paraffin were measured from 2 GHz to 15 GHz. The electromagnetic wave absorption properties were simulated and investigated in the case of normal and oblique incidence. In the normal case, the absorber achieved absorption performance of - 40 dB at 7.1 GHz. When the angle of incidence was increased to 60°, the absorption effect with reflection loss (RL) exceeding - 10 dB could still be obtained. These results demonstrate that the reported Co@C nanofiber absorber exhibits excellent absorption performance over a wide range of angle of incidence.

Differential response of hexaploid and tetraploid wheat to interactive effects of elevated [CO2] and low phosphorus.

PubMed

Pandey, Renu; Lal, Milan Kumar; Vengavasi, Krishnapriya

2018-06-04

Hexaploid wheat is more responsive than tetraploid to the interactive effects of elevated [CO 2 ] and low P in terms of carboxylate efflux, enzyme activity and gene expression (TaPT1 and TaPAP). Availability of mineral nutrients to plants under changing climate has become a serious challenge to food security and economic development. An understanding of how elevated [CO 2 ] influences phosphorus (P) acquisition processes at the whole-plant level would be critical in selecting cultivars as well as to maintain optimum yield in limited-P conditions. Wheat (Triticum aestivum and T. durum) grown hydroponically with sufficient and low P concentration were exposed to elevated and ambient [CO 2 ]. Improved dry matter partitioning towards root resulted in increased root-to-shoot ratio, root length, volume, surface area, root hair length and density at elevated [CO 2 ] with low P. Interaction of low P and [CO 2 ] induced activity of enzymes (phosphoenolpyruvate carboxylase, malate dehydrogenase and citrate synthase) in root tissue resulting in twofold increase in carboxylates and acid phosphatase exudation. Physiological absorption capacity of roots showed that plants alter their uptake kinetics by increasing affinity (low K m ) in response to elevated [CO 2 ] under low P supply. Increased relative expression of genes, purple acid phosphatase (TaPAP) and high-affinity Pi transporter (TaPT1) in roots induced by elevated [CO 2 ] and low P supported our physiological observations. Hexaploid wheat (PBW-396) being more responsive to elevated [CO 2 ] at low P supply as compared to tetraploid (PDW-233) necessitates the ploidy effect to be explored further which might be advantageous under changing climate.

Absorption cross sections of some atmospheric molecules for resonantly scattered O I 1304-A radiation

NASA Technical Reports Server (NTRS)

Starr, W. L.

1976-01-01

Absorption cross sections for O2, N2, CO2, CH4, N2O, and CO have been measured at each of the lines of the atomic oxygen triplet at 1302, 1305, and 1306 A. Radiation resonantly scattered from oxygen atoms at a temperature of about 300 K was used for the line source. Absorber temperatures were also near 300 K. Direct application of the Lambert-Beer absorption equation yielded pressure-dependent cross sections for carbon monoxide at each line of the O I triplet. Reasons for this apparent dependence are presented and discussed.

Differential Optical Absorption Spectroscopy (DOAS) using Targets: SO2 and NO2 Measurements in Montevideo City

NASA Astrophysics Data System (ADS)

Louban, Ilia; Píriz, Gustavo; Platt, Ulrich; Frins, Erna

2008-04-01

SO2 and NO2 were remotely measured in a main street of Montevideo city using Multiaxis-Differential Optical Absorption Spectroscopy (MAX-DOAS) combined with on-field selected targets. Target-based measurements are the basis of a new experimental procedure called Topographic Target Light scattering-DOAS (TOTAL-DOAS) that provides a well define absorption path to measure the near surface distribution of trace gases in the boundary layer. It combines the measurement principles of the long-path DOAS and zenith-scattered sunlight DOAS, within the near UV and VIS spectral range. We give a general description of the procedure and present first results of the 2006 campaign at Montevideo.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gorshkov, V.G.; Makarieva, A.M.

The oceanic phytoplancton productivity may essentially influence the total rate of the atmospheric CO{sub 2} absorption by the ocean - that is, a considerable amount of CO{sub 2} will be taken-up in the 50 micrometers thick layer near the air-sea interface. Even if phytoplancton production constitutes only 5% of the total oceanic biota production, this will increase the rate of CO{sub 2} absorption more than twice compared with the present estimates. The reason is that metabolic activity of phytoplancton leads to the emergence in a thin scin (50 micrometers, the average size of phytoplancton cells) layer near the water surfacemore » of an additional minimum in the CO{sub 2} partial pressure profile and of an additional maximum of {Delta} {sup 13}C in the same area. These two extremums cannot be detected if the corresponding characteristics are averaged over any microscopic area in the well mixing layer that is more than 1 meter deep, which is usually the case when the oceanic concentrations of CO{sub 2} are measured. This effect may account for the observed contradiction between the existing estimates of the rate of CO{sub 2} absorption, that are based either on measuring gradient of the concentrations of the dissolved organic and inorganic carbon or on measuring of the physical flux of CO{sub 2} through the air-sea interface.« less

Far-infrared-light shadowgraphy for high extraction efficiency of extreme ultraviolet light from a CO2-laser-generated tin plasma

NASA Astrophysics Data System (ADS)

Matsukuma, Hiraku; Hosoda, Tatsuya; Suzuki, Yosuke; Yogo, Akifumi; Yanagida, Tatsuya; Kodama, Takeshi; Nishimura, Hiroaki

2016-08-01

The two-color, double-pulse method is an efficient scheme to generate extreme ultraviolet light for fabricating the next generation semiconductor microchips. In this method, a Nd:YAG laser pulse is used to expand a several-tens-of-micrometers-scale tin droplet, and a CO2 laser pulse is subsequently directed at the expanded tin vapor after an appropriate delay time. We propose the use of shadowgraphy with a CO2 laser probe-pulse scheme to optimize the CO2 main-drive laser. The distribution of absorption coefficients is derived from the experiment, and the results are converted to a practical absorption rate for the CO2 main-drive laser.

Infrared reduction, an efficient method to control the non-linear optical property of graphene oxide in femtosecond regime

NASA Astrophysics Data System (ADS)

Bhattacharya, S.; Maiti, R.; Saha, S.; Das, A. C.; Mondal, S.; Ray, S. K.; Bhaktha, S. B. N.; Datta, P. K.

2016-04-01

Graphene Oxide (GO) has been prepared by modified Hummers method and it has been reduced using an IR bulb (800-2000 nm). Both as grown GO and reduced graphene oxide (RGO) have been characterized using Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Raman spectra shows well documented Dband and G-band for both the samples while blue shift of G-band confirms chemical functionalization of graphene with different oxygen functional group. The XPS result shows that the as-prepared GO contains 52% of sp2 hybridized carbon due to the C=C bonds and 33% of carbon atoms due to the C-O bonds. As for RGO, increment of the atomic % of the sp2 hybridized carbon atom to 83% and rapid decrease in atomic % of C=O bonds confirm an efficient reduction with infrared radiation. UV-Visible absorption spectrum also confirms increment of conjugation with increased reduction. Non-linear optical properties of both GO and RGO are measured using single beam open aperture Z-Scan technique in femtosecond regime. Intensity dependent nonlinear phenomena are observed. Depending upon the intensity, both saturable absorption and two photon absorption contribute to the non-linearity of both the samples. Saturation dominates at low intensity (~ 127 GW/cm2) while two photon absorption become prominent at higher intensities (from 217 GW/cm2 to 302 GW/cm2). We have calculated the two-photon absorption co-efficient and saturation intensity for both the samples. The value of two photon absorption co-efficient (for GO~ 0.0022-0.0037 cm/GW and for RGO~ 0.0128-0.0143 cm/GW) and the saturation intensity (for GO~57 GW/cm2 and for RGO~ 194GW/cm2) is increased with reduction. Increase in two photon absorption coefficient with increasing intensity can also suggest that there may be multi-photon absorption is taking place.

Bench-Scale Development of a Hot Carbonate Absorption Process with Crystallization-Enabled High-Pressure Stripping for Post-Combustion CO{sub 2} Capture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Yongqi; DeVries, Nicholas; Ruhter, David

A novel Hot Carbonate Absorption Process with Crystallization-Enabled High-Pressure Stripping (Hot-CAP) has been developed by the University of Illinois at Urbana-Champaign and Carbon Capture Scientific, LLC in this three-year, bench-scale project. The Hot-CAP features a concentrated carbonate solution (e.g., K{sub 2}CO{sub 3}) for CO{sub 2} absorption and a bicarbonate slurry (e.g., KHCO{sub 3}) for high-pressure CO{sub 2} stripping to overcome the energy use and other disadvantages associated with the benchmark monoethanolamine (MEA) process. The project was aimed at performing laboratory- and bench-scale experiments to prove its technical feasibility and generate process engineering and scale-up data, and conducting a techno-economic analysismore » (TEA) to demonstrate its energy use and cost competitiveness over MEA. To meet project goals and objectives, a combination of experimental, modeling, process simulation, and economic analysis studies were applied. Carefully designed and intensive experiments were conducted to measure thermodynamic and reaction engineering data relevant to four major unit operations in the Hot-CAP (i.e., CO{sub 2} absorption, CO{sub 2} stripping, bicarbonate crystallization, and sulfate reclamation). The rate promoters that could accelerate the CO{sub 2} absorption rate into the potassium carbonate/bicarbonate (PCB) solution to a level greater than that into the 5 M MEA solution were identified, and the superior performance of CO{sub 2} absorption into PCB was demonstrated in a bench-scale packed-bed column. Kinetic data on bicarbonate crystallization were developed and applied for crystallizer design and sizing. Parametric testing of high-pressure CO{sub 2} stripping with concentrated bicarbonate-dominant slurries at high temperatures ({>=}140{degrees}C) in a bench-scale stripping column demonstrated lower heat use than with MEA. The feasibility of a modified process for combining SO{sub 2} removal with CO{sub 2} capture was preliminarily demonstrated. In addition to the experimental studies, the technical challenges pertinent to fouling of slurry-handling equipment and the design of the crystallizer and stripper were addressed through consultation with vendors and engineering analyses. A process flow diagram of the Hot-CAP was then developed and a TEA was performed to compare the energy use and cost performance of a nominal 550-MWe subcritical pulverized coal (PC)-fired power plant without CO{sub 2} capture (DOE/NETL Case 9) with the benchmark MEA-based post-combustion CO{sub 2} capture (PCC; DOE/NETL Case 10) and the Hot-CAP-based PCC. The results revealed that the net power produced in the PC + Hot-CAP is 609 MWe, greater than the PC + MEA (550 MWe). The 20-year levelized cost of electricity (LCOE) for the PC + Hot-CAP, including CO{sub 2} transportation and storage, is 120.3 mills/kWh, a 60% increase over the base PC plant without CO{sub 2} capture. The LCOE increase for the Hot-CAP is 29% lower than that for MEA. TEA results demonstrated that the Hot-CAP is energy-efficient and cost-effective compared with the benchmark MEA process.« less

H2, CO, and dust absorption through cold molecular clouds

NASA Astrophysics Data System (ADS)

Lacy, John H.; Sneden, Chris; Kim, Hwihyun; Jaffe, Daniel Thomas

2017-06-01

We have made observations with IGRINS on the Harlan J. Smith telescope at McDonald Observatory of near-infrared absorption by H2, CO, and dust toward stars behind molecular clouds, primarily the TMC. Prior to these observations, the abundance of H2 in molecular clouds, relative to the commonly used tracer CO, had only been measured toward a few embedded stars, which may be surrounded by atypical gas. The new observations provide a representative sample of these molecules in cold molecular gas. We find N(H2)/Av ~ 0.9e+21, N(CO)/Av ~ 1.6e+17, and H2/CO ~ 6000. The measured H2/CO ratio is consistent with that measured toward embedded stars in various molecular clouds, but half that derived from mm-wave observations of CO emission and star counts or other determinations of Av.

FTIR spectroscopic, thermal and XRD characterization of hydroxyapatite from new natural sources

NASA Astrophysics Data System (ADS)

Shaltout, Abdallah A.; Allam, Moussa A.; Moharram, Mohamed A.

2011-12-01

The inorganic constituents of 5 different plants (leaves and stalks) were investigated by using Fourier transformer infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermal analysis including thermal gravimetric analysis (TGA), derivative thermogravimetry (DTG) and differential scanning calorimetry (DSC). These plants are Catha edulis (Khat), basil, mint, green tea and trifolium. The absorption bands of carbonate ions CO 32- was exhibited at 1446 cm -1, and the phosphate ions PO 43- was assigned at 1105 and 1035 cm -1. At high temperatures (600, 700 and 600 °C) further absorption bands of the phosphate ions PO 43- was assigned at the frequencies 572, 617, 962, 1043 and 1110 cm -1 and the vibrational absorption band of the carbonate ions CO 32- was assigned at 871, 1416 and 1461 cm -1. X-ray diffraction and thermal analysis confirm the obtained results of FITR. Results showed that the main inorganic constituents of C. edulis and basil leaves are hydroxyapatite whereas the hydroxyapatite content in the other plant samples is less than that in case of C. edulis and basil plant leaves.

Improved visible-light photocatalytic activity of TiO2 co-doped with copper and iodine

NASA Astrophysics Data System (ADS)

Dorraj, Masoumeh; Goh, Boon Tong; Sairi, Nor Asrina; Woi, Pei Meng; Basirun, Wan Jefrey

2018-05-01

Cu-I-co-doped TiO2 photocatalysts active to visible light absorption were prepared by hydrothermal method and calcined at various temperatures (350 °C, 450 °C, and 550 °C). The co-doped powders at 350 °C displayed the highest experimental Brunauer-Emmett-Teller surface area and lowest photoluminescence intensity, which demonstrated that a decrease in electron-hole recombination process. The synthesis of co-doped TiO2 was performed at this optimized temperature. In the co-doped sample, the Cu2+ doped TiO2 lattice created a major "red-shift" in the absorption edge due to the presence of the 3d Cu states, whereas the amount of red-shift from the I5+ doping in the TiO2 lattice was minor. Interestingly, the presence of Cu2+ species also boosted the reduction of I5+ ions to the lower multi-valance state I- in the TiO2 lattice by trapping the photogenerated electrons, which resulted in effective separation of the photogenerated charges. The Cu-I-co-doped TiO2 was able to degrade methyl orange dye under visible-light irradiation with improved photocatalytic activity compared with the single metal-doped TiO2 and pure TiO2 because of the strong visible light absorption and effective separation of photogenerated charges caused by the synergistic effects of Cu and I co-dopants.

AKARI observations of brown dwarfs. IV. Effect of elemental abundances on near-infrared spectra between 1.0 and 5.0 μm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sorahana, S.; Yamamura, I.

2014-09-20

The detection of the CO{sub 2} absorption band at 4.2 μm in brown dwarf spectra by AKARI has made it possible to discuss CO{sub 2} molecular abundance in brown dwarf atmospheres. In our previous studies, we found an excess in the 4.2 μm CO{sub 2} absorption band of three brown dwarf spectra, and suggested that these deviations were caused by high C and O elemental abundances in their atmospheres. To validate this hypothesis, we have constructed a set of models of brown dwarf atmospheres with various elemental abundance patterns, and we investigate the variations of the molecular composition and themore » thermal structure, and how they affect the near-infrared spectra between 1.0 and 5.0 μm. The 4.2 μm CO{sub 2} absorption band in some late-L and T dwarfs taken by AKARI is stronger or weaker than predicted by corresponding models with solar abundance. By comparing the CO{sub 2} band in the model spectra to the observed near-infrared spectra, we confirm possible elemental abundance variations among brown dwarfs. We find that the band strength is especially sensitive to O abundance, but C is also needed to reproduce the entire near-infrared spectra. This result indicates that both the C and O abundances should increase and decrease simultaneously for brown dwarfs. We find that a weaker CO{sub 2} absorption band in a spectrum can also be explained by a model with lower 'C and O' abundances.« less

Single Longitudinal Mode, High Repetition Rate, Q-switched Ho:YLF Laser for Remote Sensing

NASA Technical Reports Server (NTRS)

Bai, Yingxin; Yu, Jirong; Petzar, Paul; Petros, M.; Chen, Songsheng; Trieu, Bo; Lee, Nyung; Singh, U.

2009-01-01

Ho:YLF/LuLiF lasers have specific applications for remote sensing such as wind-speed measurement and carbon dioxide (CO2) concentration measurement in the atmosphere because the operating wavelength (around 2 m) is located in the eye-safe range and can be tuned to the characteristic lines of CO2 absorption and there is strong backward scattering signal from aerosol (Mie scattering). Experimentally, a diode pumped Ho:Tm:YLF laser has been successfully used as the transmitter of coherent differential absorption lidar for the measurement of with a repetition rate of 5 Hz and pulse energy of 75 mJ [1]. For highly precise CO2 measurements with coherent detection technique, a laser with high repetition rate is required to averaging out the speckle effect [2]. In addition, laser efficiency is critically important for the air/space borne lidar applications, because of the limited power supply. A diode pumped Ho:Tm:YLF laser is difficult to efficiently operate in high repetition rate due to the large heat loading and up-conversion. However, a Tm:fiber laser pumped Ho:YLF laser with low heat loading can be operated at high repetition rates efficiently [3]. No matter whether wind-speed or carbon dioxide (CO2) concentration measurement is the goal, a Ho:YLF/LuLiF laser as the transmitter should operate in a single longitudinal mode. Injection seeding is a valid technique for a Q-switched laser to obtain single longitudinal mode operation. In this paper, we will report the new results for a single longitudinal mode, high repetition rate, Q-switched Ho:YLF laser. In order to avoid spectral hole burning and make injection seeding easier, a four mirror ring cavity is designed for single longitudinal mode, high repetition rate Q-switched Ho:YLF laser. The ramp-fire technique is chosen for injection seeding.

[Study on the effect of solar spectra on the retrieval of atmospheric CO2 concentration using high resolution absorption spectra].

PubMed

Hu, Zhen-Hua; Huang, Teng; Wang, Ying-Ping; Ding, Lei; Zheng, Hai-Yang; Fang, Li

2011-06-01

Taking solar source as radiation in the near-infrared high-resolution absorption spectrum is widely used in remote sensing of atmospheric parameters. The present paper will take retrieval of the concentration of CO2 for example, and study the effect of solar spectra resolution. Retrieving concentrations of CO2 by using high resolution absorption spectra, a method which uses the program provided by AER to calculate the solar spectra at the top of atmosphere as radiation and combine with the HRATS (high resolution atmospheric transmission simulation) to simulate retrieving concentration of CO2. Numerical simulation shows that the accuracy of solar spectrum is important to retrieval, especially in the hyper-resolution spectral retrieavl, and the error of retrieval concentration has poor linear relation with the resolution of observation, but there is a tendency that the decrease in the resolution requires low resolution of solar spectrum. In order to retrieve the concentration of CO2 of atmosphere, the authors' should take full advantage of high-resolution solar spectrum at the top of atmosphere.

Remarkable optical red shift and extremely high optical absorption coefficient of V-Ga co-doped TiO2

NASA Astrophysics Data System (ADS)

Deng, Quanrong; Han, Xiaoping; Gao, Yun; Shao, Guosheng

2012-07-01

A first attempt has been made to study the effect of codoping of transition metal and sp metal on the electronic structure and associated optical properties of TiO2, through V-Ga codoped thin films. V-Ga codoped rutile TiO2 films were fabricated on fused quartz substrates using pulsed laser ablation, followed by heat treatment at high temperatures. Gigantic redshift in the optical absorption edge was observed in V-Ga co-doped TiO2 materials, from UV to infrared region with high absorption coefficient. Through combined structural characterization and theoretical modeling, this is attributed to the p-d hybridization between the two metals. This leads to additional energy bands to overlap with the minimum of the conduction band, leading to remarkably narrowed band gap free of mid-gap states. The direct-gap of the co-doped phase is key to the remarkably high optical absorption coefficient of the coped titania.

Line by Line Analysis of Carbon Dioxide Absorption for Predicting Global Warming

NASA Astrophysics Data System (ADS)

Smith, D. C.

2010-12-01

The anthropologic cause of global warming rests on the impact of CO2 on the green house effect. Previous derivations of the increase in the CO2 Forcing Function caused by doubling of atmospheric CO2 from 320 ppm to 640 ppm reported a value of 4 W/M2( Ramananathan,V,et al, J.of Geophysical Research Vol 84, C8,p4949, Aug.1979) This value leads to a calculated temperature rise of 1 deg.K (Charney,J. et al,”Carbon Dioxide and Climate: A Scientific Assessment”, National Academy of Science, Washington D.C., 1979). This increase in global temperature leads to an increase in water vapor if it is assumed that the relative humidity is constant. This ampflication leads to a calculated temperature rise of an additional 2 deg.K. Different arguments as to the effects of the earth’s albido change, clouds, and the oceans also impact the earths global warming with predictions of total temperature rise of as high as 6 deg.K { IPCC,2007 Summary for Policymakers. In: Climate Change 2007: The Physical Sciences Basis. Contributions of Working Group 1 to the Fourth Assessment Report of the IPCC [ Solomon,S,D. et al (eds)] Cambridge University Press, NY,USA}. Regardless of the other effects, the only way that man can be held responsible for global warming is by CO2 emissions and the resulting increase in the Forcing Function. This paper challenges the magnitude of the 4 W/M2 Forcing Function. The earth radiates in the 4 to 30 micron wavelength range. CO2 has absorption bands in the 4, 10, and 15 micron wavelengths (Hertzberg G. Molecular Spectra & Molecular Structure,Norstrand Co.,1960). McClatchey has tabulated the line stengths for all CO2 transitions and they are used to calculate the atmospheric absorption (McClatchey,R, et al “AFCRL Atmospheric Absorption Line Parameter Compilation”,AFCRL-TR-0096,1973). Detailed calculations of the CO2 line absorption in the 8 to 12 micron atmospheric window shows an increase of 0.3 W/M2 for CO2 doubling. The increase in absorbed fluence in the 12 to 20 micron range is 0.8 W/M2. The increase in the 4 micron band is 0.01 W/M2. (The very strong absorption lines are saturated at CO2 levels of 320 ppm). The total increase in absorbed IR fluence for doubling CO2 is 1.1 W/M2 Detailed calculations of how this absorbed energy heats the earth and what fraction escapes to space must be done for a definitive answer as to what the increase in the Forcing Function is for doubled CO2. Even if all of the absorbed radiation were delivered to the earth, the temperature rise due to doubling CO2 would be 0.26 deg.K. Up to 1/2 the absorbed fluence can be convected/radiated to outer space, which would lead to a temperature rise of 0.13 deg.K. (There is the amplification factor due to increased water vapor that must be added to the direct CO2 contribution but this is also signicantly reduced relative to the 2 deg.K presently accepted). The important difference between the results of this study and the previous predictions, (4W/M2), is probably due to the saturation of the lines which is obscured by band model calculations and is not in the line by line calculations. The conclusion is that man’s contribution to global warming is small.

Pre-Combustion Carbon Capture by a Nanoporous, Superhydrophobic Membrane Contactor Process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meyer, Howard; Zhou, S James; Ding, Yong

2012-03-31

This report summarizes progress made during Phase I and Phase II of the project: "Pre-Combustion Carbon Capture by a Nanoporous, Superhydrophobic Membrane Contactor Process," under contract DE-FE-0000646. The objective of this project is to develop a practical and cost effective technology for CO{sub 2} separation and capture for pre-combustion coal-based gasification plants using a membrane contactor/solvent absorption process. The goals of this technology development project are to separate and capture at least 90% of the CO{sub 2} from Integrated Gasification Combined Cycle (IGCC) power plants with less than 10% increase in the cost of energy services. Unlike conventional gas separationmore » membranes, the membrane contactor is a novel gas separation process based on the gas/liquid membrane concept. The membrane contactor is an advanced mass transfer device that operates with liquid on one side of the membrane and gas on the other. The membrane contactor can operate with pressures that are almost the same on both sides of the membrane, whereas the gas separation membranes use the differential pressure across the membrane as driving force for separation. The driving force for separation for the membrane contactor process is the chemical potential difference of CO{sub 2} in the gas phase and in the absorption liquid. This process is thus easily tailored to suit the needs for pre-combustion separation and capture of CO{sub 2}. Gas Technology Institute (GTI) and PoroGen Corporation (PGC) have developed a novel hollow fiber membrane technology that is based on chemically and thermally resistant commercial engineered polymer poly(ether ether ketone) or PEEK. The PEEK membrane material used in the membrane contactor during this technology development program is a high temperature engineered plastic that is virtually non-destructible under the operating conditions encountered in typical gas absorption applications. It can withstand contact with most of the common treating solvents. GTI and PGC have developed a nanoporous and superhydrophobic PEEK-based hollow fiber membrane contactor tailored for the membrane contactor/solvent absorption application for syngas cleanup. The membrane contactor modules were scaled up to 8-inch diameter commercial size modules. We have performing extensive laboratory and bench testing using pure gases, simulated water-gas-shifted (WGS) syngas stream, and a slipstream from a gasification derived syngas from GTI's Flex-Fuel Test Facility (FFTF) gasification plant under commercially relevant conditions. The team have also carried out an engineering and economic analysis of the membrane contactor process to evaluate the economics of this technology and its commercial potential. Our test results have shown that 90% CO{sub 2} capture can be achieved with several physical solvents such as water and chilled methanol. The rate of CO{sub 2} removal by the membrane contactor is in the range of 1.5 to 2.0 kg/m{sup 2}/hr depending on the operating pressures and temperatures and depending on the solvents used. The final economic analysis has shown that the membrane contactor process will cause the cost of electricity to increase by 21% from the base plant without CO{sub 2} capture. The goal of 10% increase in levelized cost of electricity (LCOE) from base DOE Case 1(base plant without capture) is not achieved by using the membrane contactor. However, the 21% increase in LCOE is a substantial improvement as compared with the 31.6% increase in LCOE as in DOE Case 2(state of art capture technology using 2-stages of Selexol{TM}).« less

Coherent vibrational climbing in carboxyhemoglobin

PubMed Central

Ventalon, Cathie; Fraser, James M.; Vos, Marten H.; Alexandrou, Antigoni; Martin, Jean-Louis; Joffre, Manuel

2004-01-01

We demonstrate vibrational climbing in the CO stretch of carboxyhemoglobin pumped by midinfrared chirped ultrashort pulses. By use of spectrally resolved pump-probe measurements, we directly observed the induced absorption lines caused by excited vibrational populations up to v = 6. In some cases, we also observed stimulated emission, providing direct evidence of vibrational population inversion. This study provides important spectroscopic parameters on the CO stretch in the strong-field regime, such as transition frequencies and dephasing times up to the v = 6to v = 7 vibrational transition. We measured equally spaced vibrational transitions, in agreement with the energy levels of a Morse potential up to v = 6. It is interesting that the integral of the differential absorption spectra was observed to deviate far from zero, in contrast to what one would expect from a simple one-dimensional Morse model assuming a linear dependence of dipole moment with bond length. PMID:15319472

[Research on the method of interference correction for nondispersive infrared multi-component gas analysis].

PubMed

Sun, You-Wen; Liu, Wen-Qing; Wang, Shi-Mei; Huang, Shu-Hua; Yu, Xiao-Man

2011-10-01

A method of interference correction for nondispersive infrared multi-component gas analysis was described. According to the successive integral gas absorption models and methods, the influence of temperature and air pressure on the integral line strengths and linetype was considered, and based on Lorentz detuning linetypes, the absorption cross sections and response coefficients of H2O, CO2, CO, and NO on each filter channel were obtained. The four dimension linear regression equations for interference correction were established by response coefficients, the absorption cross interference was corrected by solving the multi-dimensional linear regression equations, and after interference correction, the pure absorbance signal on each filter channel was only controlled by the corresponding target gas concentration. When the sample cell was filled with gas mixture with a certain concentration proportion of CO, NO and CO2, the pure absorbance after interference correction was used for concentration inversion, the inversion concentration error for CO2 is 2.0%, the inversion concentration error for CO is 1.6%, and the inversion concentration error for NO is 1.7%. Both the theory and experiment prove that the interference correction method proposed for NDIR multi-component gas analysis is feasible.

Application of NIR Laser Spectroscopy to the Monitoring of Volcanic Plumes: Principles and Practicalities

NASA Astrophysics Data System (ADS)

Hamish, A.; Christenson, B. W.; Mazot, A.

2014-12-01

The major volatile species in volcanic plume emissions (i.e., H2O, CO2, SO2, HCl, HF) are all strongly infrared (IR)-active, and lend themselves to infrared spectroscopic analysis. However, physical/optical access to plume gases along pathways which include a suitable natural or active IR radiation source is often difficult or impossible to achieve, particularly for timeframes extending beyond short campaign periods. In this study, we present results from preliminary tests conducted on three volcanic CO2 plume emissions using a tunable diode NIR laser system (TDL, Boreal Laser Inc.). The approach is proving itself as a good candidate for continuous monitoring of volcanic plume CO2, and by default all other IR-active constituents for which lasers of appropriate wavelength are available. The CO2 system is configured with a TDL in a transceiver generating laser light which can be tuned to coincide with one of several absorption lines in the CO2 absorption band between 1575 nm and 1585 nm. This beam propagates through the atmosphere (and plume) to a retro-reflector, which returns the beam to a photodiode detector in the transceiver which processes the signal to report real time CO2 column densities. The CO2 absorption line at 1579.1 nm was used to good effect on Mt Ruapehu (NZ) where volcanic gases emanate through a 100 m deep crater lake, resulting in CO2 concentrations of > 78 ppm above background in the mixing zone varying from 4 to 30 m above the lake surface. Subsequent tests on the main plume at White Island, however, generated only poor results with indicated CO2 amounts being less than atmospheric. We concluded that this was the result of interference from a neighboring but comparatively minor H2O absorption band which in the proximal, higher temperature plume (estimated 50-70 °C), had H2O concentrations some 4-5 times greater than ambient. A change to a less sensitive absorption line further removed from potential H2O band interference (1567.9 nm) appears to have solved this problem, and yielded maximum CO2 concentrations along the 730 m pathway in excess of 500 ppm.This approach holds promise for continuous, real-time monitoring of volcanic plume chemistry, and we will now turn our focus to the detection of SO2, HCl and HF plume species.

Influence of the concentration of CO2 and SO2 on the absorption of CO2 by a lithium orthosilicate-based absorbent.

PubMed

Pacciani, R; Torres, J; Solsona, P; Coe, C; Quinn, R; Hufton, J; Golden, T; Vega, L F

2011-08-15

A novel, high temperature solid absorbent based on lithium orthosilicate (Li(4)SiO(4)) has shown promise for postcombustion CO(2) capture. Previous studies utilizing a clean, synthetic flue gas have shown that the absorbent has a high CO(2) capacity, >25 wt %, along with high absorption rates, lower heat of absorption and lower regeneration temperature than other solids such as calcium oxide. The current effort was aimed at evaluating the Li(4)SiO(4) based absorbent in the presence of contaminants found in typical flue gas, specifically SO(2), by cyclic exposure to gas mixtures containing CO(2), H(2)O (up to 25 vol. %), and SO(2) (up to 0.95 vol. %). In the absence of SO(2), a stable CO(2) capacity of ∼ 25 wt % over 25 cycles at 550 °C was achieved. The presence of SO(2), even at concentrations as low as 0.002 vol. %, resulted in an irreversible reaction with the absorbent and a decrease in CO(2) capacity. Analysis of SO(2)-exposed samples revealed that the absorbent reacted chemically and irreversibly with SO(2) at 550 °C forming Li(2)SO(4). Thus, industrial application would require desulfurization of flue gas prior to contacting the absorbent. Reactivity with SO(2) is not unique to the lithium orthosilicate material, so similar steps would be required for other absorbents that chemically react with SO(2).

Synthesis, structural, magnetic and optical properties of Sr2CoSn based inverse Heusler alloy nanoparticles

NASA Astrophysics Data System (ADS)

Asvini, V.; Saravanan, G.; Kalaiezhily, R. K.; Ravichandran, K.

2018-05-01

The peculiar ternary full Heusler alloy Sr2CoSn nanoparticles are synthesized by co-precipitation method. X- ray diffraction pattern confirms the formation of XA or Xα structure of Sr2CoSn. Using Williamson-Hall plot (W-H plot), we are able to use the uniform deformation model and get low value of strain induced broadening. UV-Visible absorption spectrum shows sharp absorption peak at 210 nm and the estimated band gap energy of Sr2CoSn Heusler alloy nanoparticles is Eg = 4.6 eV (from Tauc plot). The presence of Sr2CoSn with the particle size of approximately 90 nm was observed using high resolution scanning electron microscopy. The magnetization measurements were carried out using VSM and studied M verses H hysteresis studies.

Simultaneous and Independent Measurement of Atmospheric Water Vapor and Carbon Dioxide using a Triple-Pulsed, 2-micron Airborne IPDA Lidar - A Feasibility Study

NASA Astrophysics Data System (ADS)

Singh, U. N.; Refaat, T. F.; Yu, J.; Petros, M.

2013-12-01

Water vapor (H2O) and carbon dioxide (CO2) are dominant greenhouse gases that are critical for Earth's radiation budget and global warming through the eco-system and the carbon cycle. NASA Langley Research Center (LaRC) has a strong heritage in atmospheric remote sensing of both gases using several instruments adopting various DIAL techniques. This communication presents a feasibility study for measuring both H2O and CO2 simultaneously and independently using a single instrument. This instrument utilizes the Integrated Path Differential Absorption (IPDA) lidar technique to measure the weighted-average column dry-air mixing ratios of CO2 (XCO2) and H2O (XH2O) independently and simultaneously from an airborne platform. The key component of this instrument is a tunable triple-pulse 2-micron laser. The three laser pulses are transmitted sequentially within a short time interval of 200 microsec. The wavelength of each of the laser pulses can be tuned separately. The IPDA receiver design is based on low-risk, commercially available components, including 300-micron diameter InGaAs 2-micron pin detector, a low-noise, high speed trans-impedance amplifier (TIA) and 12-bit 400 MHz digitizer.

High-Resolution Near-Infrared Spectroscopy of FU Orionis Objects

NASA Astrophysics Data System (ADS)

Hartmann, Lee; Hinkle, Kenneth; Calvet, Nuria

2004-07-01

We present an analysis of recent near-infrared, high-resolution spectra of the variable FU Ori objects. During a phase of rapid fading in optical brightness during 1997, V1057 Cyg exhibited shell absorption in first-overtone (v''-v'=2-0) CO lines, blueshifted by about 50 km s-1 from the system velocity. This shell component had not been seen previously, nor was it present in 1999, although some blueshifted absorption asymmetry is seen at the latter epoch. The appearance of this CO absorption shell is connected with the roughly contemporaneous appearance of blueshifted, low-excitation optical absorption lines with comparable low velocities; we suggest that this shell was also responsible for some of the peculiar emission features seen in red-optical spectra of V1057 Cyg. FU Ori continues to exhibit broad CO lines, with some evidence for the double-peaked profiles characteristic of an accretion disk; the line profiles are consistent with previous observations. Both FU Ori and V1057 Cyg continue to exhibit lower rotational broadening at 2.3 μm than at optical wavelengths, in agreement with the prediction of differentially rotating disk models; we have a marginal detection of the same effect in V1515 Cyg. The relative population of the first-overtone CO rotational levels in the FU Ori objects suggests low excitation temperatures. We compare disk models to the observations and find agreement with overall line strengths and rotational broadening, but the observed line profiles are generally less double-peaked than predicted. We suggest that the discrepancy in line profiles is due to turbulent motions in FU Ori disks, an effect qualitatively predicted by recent simulations of the magnetorotational instability in vertically stratified accretion disks. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under a cooperative agreement with the NSF, on behalf of the Gemini partnership: the National Science Foundation (United States), the Particle Physics and Astronomy Research Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), CNPq (Brazil), and CONICRT (Argentina). Based on observations obtained with the Phoenix infrared spectrograph, developed and operated by the National Optical Astronomy Observatory. The National Optical Astronomy Observatory is operated by the AURA, Inc. under cooperative agreement with the National Science Foundation.

Large-scale synthesis and microwave absorption enhancement of actinomorphic tubular ZnO/CoFe2O4 nanocomposites.

PubMed

Cao, Jing; Fu, Wuyou; Yang, Haibin; Yu, Qingjiang; Zhang, Yanyan; Liu, Shikai; Sun, Peng; Zhou, Xiaoming; Leng, Yan; Wang, Shuangming; Liu, Bingbing; Zou, Guangtian

2009-04-09

Actinomorphic tubular ZnO/CoFe(2)O(4) nanocomposites were fabricated in large scale via a simple solution method at low temperature. The phase structures, morphologies, particle size, shell thickness, chemical compositions of the composites have been characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), energy dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM). The as-synthesized nanocomposites were uniformly dispersed into the phenolic resin then the mixture was pasted on metal plate with the area of 200 mm x 200 mm as the microwave absorption test plate. The test of microwave absorption was carried out by the radar-absorbing materials (RAM) reflectivity far field radar cross-section (RCS) method. The range of microwave absorption is from 2 to 18 Hz and the best microwave absorption reach to 28.2 dB at 8.5 Hz. The results indicate that the composites are of excellence with respect to microwave absorption.

Modeling the reflectance of CO2 frost with new optical constants: Application to Martian south polar cap spectra

NASA Technical Reports Server (NTRS)

Hansen, Gary B.; Martin, Terry Z.

1993-01-01

New measurements of the absorption coefficients of CO2 ice, in most of the spectral range 0.2 to 3.9 microns where absorption coefficients are below 1.5 per cm, have recently been made. Although these measurements are preliminary, they contain spectral detail not seen previously in the literature. Therefore, it is useful to combine these new data with older data from spectral regions of stronger absorption and reformulate models of the albedo or reflectance of CO2 frost. These models can then be adjusted in an attempt to match measurements of Martian polar deposits, such as the set of spectra returned by the IRS instrument on Mariner 7 (1969). The new absorption coefficients of CO2 ice were measured on several samples of 41-mm thickness at 150-155 K. A portion of the spectrum from 1.9 to 3.9 microns wavelength is shown in the form of imaginary coefficient of refraction ( = linear absorption x wavelength / 4 pi). The data above 3x10(exp -5) are obtained from, except for the absorption line at 3.32 micrometers, which is extrapolated in a way that is consistent with laboratory frost measurements, but the peak level is still highly uncertain. This new imagary coefficient, combined with the real coefficient, can be immediately applied to the models for hemispherical albedo, resulting in markedly different results from those in that study. The results for an infinite optical depth layer and solar incidence of 60 degrees are plotted for a range of mean particle radii from 0.03 to 3 mm.

The Physical Character of the Au (001) Surface Reconstruction in the Presence of CO and O2

NASA Astrophysics Data System (ADS)

Loheac, Andrew; Pierce, Michael S.; Barbour, Andi; Komanicky, Vladimir; Zhu, Chenhui; You, Hoydoo

2014-03-01

The interaction of carbon monoxide and oxygen on Au (001) single crystal facets has been investigated using synchrotron based surface x-ray diffraction and scattering techniques. Preliminary experiments confirm the quasi-hexagonal surface reconstruction can be influenced by exposure to CO and O, and indicate that oxidation may be present. Subsequent surface x-ray scattering experiments included a residual gas analyzer (RGA) with isotopic CO to tag the chemical species. Both CO (by itself) and O (dissociated from molecular O2 by the x-rays) are capable of lifting the hexagonal surface reconstruction resulting in a disordered bulk truncated surface. A wide range of pressures (1 mTorr - 10 Torr) and temperatures (300 K - 900 K) have been explored. We have also adapted a system of coupled partial differential equations to model the absorption kinetics and surface reconstructions. This work and use of the Advanced Photon Source were supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The work at Safarik University was supported by Slovak grant VEGA 1/0782/12.

Secondary Amine Functional Disiloxanes as CO2 Sorbents

DOE Office of Scientific and Technical Information (OSTI.GOV)

O'Brien, MJ; Farnum, RL; Perry, RJ

2014-05-01

A series of two different types of secondary amine functional disiloxanes were prepared and screened as CO2 capture solvents. The first group of materials contained RNHCH2CH2CH2 side chains where the R groups were C1-6 alkyls. When R was a primary alkyl group, these materials exhibited CO2 uptake values slightly in excess of theoretical. As the alkyl groups were changed to more sterically hindered secondary or tertiary alkyls, the uptake was less efficient. Heats of absorption values for these materials were generally in the range 2000-2200 kJ/kg of CO2, values significantly lower than those obtained for primary amine functional disiloxanes (2500-2700more » kJ/kg of CO2). Also explored were a series of secondary amine functional disiloxanes with X-CH2CH2NH-CH2CH2CH2 - substituents. When X was an electron-donating group (RO-, R2N-, RO-CH2-) the CO2 uptake was also in excess of theoretical. Interestingly, these compounds were generally found to produce carbamate salts that were flowable, low-viscosity oils. Furthermore, the heat of absorption values determined for these materials were even lower. Most compounds gave values below 2000 kJ/kg of CO2. Overall the most promising results were obtained with a methoxyethylaminopropyl derivative, an ethoxyethylaminopropyl-containing material, and a dimethylaminoethylaminopropyl-based compound. These materials showed excellent CO2 uptake, had low heats of absorption, and produced carbamate salts that were flowable liquids even at room temperature.« less

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Remote laser detection of natural gas leakages from pipelines

NASA Astrophysics Data System (ADS)

Petukhov, V. O.; Gorobets, V. A.; Andreev, Yu M.; Lanskii, G. V.

2010-02-01

A differential absorption lidar based on a tunable TEA CO2 laser emitting at 42 lines of the 'hot' 0111 — 1110 band in the range from 10.9 to 11.4 μm is developed for detecting natural gas leakages from oil pipelines by measuring the ethane content in the atmosphere. The ethane detection sensitivity is 0.9 ppm km. The presence of methane does not distort the measurement results. The developed lidar can detect the natural gas leakage from kilometre heights at the flying velocities up to 200 km h-1 and a probe pulse repetition rate of 5 Hz.

Advanced intensity-modulation continuous-wave lidar techniques for ASCENDS CO2 column measurements

NASA Astrophysics Data System (ADS)

Campbell, Joel F.; Lin, Bing; Nehrir, Amin R.; Harrison, F. W.; Obland, Michael D.; Meadows, Byron

2015-10-01

Global atmospheric carbon dioxide (CO2) measurements for the NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) space mission are critical for improving our understanding of global CO2 sources and sinks. Advanced Intensity- Modulated Continuous-Wave (IM-CW) lidar techniques are investigated as a means of facilitating CO2 measurements from space to meet the ASCENDS measurement requirements. In recent numerical, laboratory and flight experiments we have successfully used the Binary Phase Shift Keying (BPSK) modulation technique to uniquely discriminate surface lidar returns from intermediate aerosol and cloud contamination. We demonstrate the utility of BPSK to eliminate sidelobes in the range profile as a means of making Integrated Path Differential Absorption (IPDA) column CO2 measurements in the presence of optically thin clouds, thereby eliminating the need to correct for sidelobe bias errors caused by the clouds. Furthermore, high accuracy and precision ranging to the surface as well as to the top of intermediate cloud layers, which is a requirement for the inversion of column CO2 number density measurements to column CO2 mixing ratios, has been demonstrated using new hyperfine interpolation techniques that takes advantage of the periodicity of the modulation waveforms. This approach works well for both BPSK and linear swept-frequency modulation techniques. The BPSK technique under investigation has excellent auto-correlation properties while possessing a finite bandwidth. A comparison of BPSK and linear swept-frequency is also discussed in this paper. These results are extended to include Richardson-Lucy deconvolution techniques to extend the resolution of the lidar beyond that implied by limit of the bandwidth of the modulation, where it is shown useful for making tree canopy measurements.

Advanced IMCW Lidar Techniques for ASCENDS CO2 Column Measurements

NASA Astrophysics Data System (ADS)

Campbell, Joel; lin, bing; nehrir, amin; harrison, fenton; obland, michael

2015-04-01

Global atmospheric carbon dioxide (CO2) measurements for the NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) space mission are critical for improving our understanding of global CO2 sources and sinks. Advanced Intensity-Modulated Continuous-Wave (IM-CW) lidar techniques are investigated as a means of facilitating CO2 measurements from space to meet the ASCENDS measurement requirements. In recent numerical, laboratory and flight experiments we have successfully used the Binary Phase Shift Keying (BPSK) modulation technique to uniquely discriminate surface lidar returns from intermediate aerosol and cloud contamination. We demonstrate the utility of BPSK to eliminate sidelobes in the range profile as a means of making Integrated Path Differential Absorption (IPDA) column CO2 measurements in the presence of optically thin clouds, thereby eliminating the need to correct for sidelobe bias errors caused by the clouds. Furthermore, high accuracy and precision ranging to the surface as well as to the top of intermediate cloud layers, which is a requirement for the inversion of column CO2 number density measurements to column CO2 mixing ratios, has been demonstrated using new hyperfine interpolation techniques that takes advantage of the periodicity of the modulation waveforms. This approach works well for both BPSK and linear swept-frequency modulation techniques. The BPSK technique under investigation has excellent auto-correlation properties while possessing a finite bandwidth. A comparison of BPSK and linear swept-frequency is also discussed in this paper. These results are extended to include Richardson-Lucy deconvolution techniques to extend the resolution of the lidar beyond that implied by limit of the bandwidth of the modulation.

Advanced Intensity-Modulation Continuous-Wave Lidar Techniques for Column CO2 Measurements

NASA Astrophysics Data System (ADS)

Campbell, J. F.; Lin, B.; Nehrir, A. R.; Obland, M. D.; Liu, Z.; Browell, E. V.; Chen, S.; Kooi, S. A.; Fan, T. F.

2015-12-01

Global and regional atmospheric carbon dioxide (CO2) measurements for the NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) space mission and Atmospheric Carbon and Transport (ACT) - America airborne investigation are critical for improving our understanding of global CO2 sources and sinks. Advanced Intensity-Modulated Continuous-Wave (IM-CW) lidar techniques are being investigated as a means of facilitating CO2 measurements from space and airborne platforms to meet the mission science measurement requirements. In recent numerical, laboratory and flight experiments we have successfully used the Binary Phase Shift Keying (BPSK) modulation technique to uniquely discriminate surface lidar returns from intermediate aerosol and cloud returns. We demonstrate the utility of BPSK to eliminate sidelobes in the range profile as a means of making Integrated Path Differential Absorption (IPDA) column CO2 measurements in the presence of intervening optically thin clouds, thereby minimizing bias errors caused by the clouds. Furthermore, high accuracy and precision ranging to the Earth's surface as well as to the top of intermediate cloud layers, which is a requirement for the inversion of column CO2 number density measurements to column CO2 mixing ratios, has been demonstrated using new hyperfine interpolation techniques that takes advantage of the periodicity of the modulation waveforms. This approach works well for both BPSK and linear swept-frequency modulation techniques and provides very high (at sub-meter level) range resolution. The BPSK technique under investigation has excellent auto-correlation properties while possessing a finite bandwidth. A comparison of BPSK and linear swept-frequency is also discussed in this paper. These techniques are used in a new data processing architecture to support the ASCENDS CarbonHawk Experiment Simulator (ACES) and ACT-America programs.

Development of a high-speed wavelength-agile CO2 local oscillator for heterodyne DIAL measurements

NASA Astrophysics Data System (ADS)

Senft, Daniel C.; Pierrottet, Diego F.

2002-06-01

A high repetition rate, wavelength agile CO2 laser has been developed at the Air Force Research Laboratory for use as a local oscillator in a heterodyne detection receiver. Fats wavelength selection is required for measurements of airborne chemical vapors using the differential absorption lidar (DIAL) technique. Acousto-optic modulator are used to tune between different wavelengths at high speeds without the need for moving mechanical parts. Other advantages obtained by the use of acousto-optic modulators are laser output power control per wavelength and rugged packaging for field applications. The local oscillator design is described, and the results from laboratory DIAL measurements are presented. The coherent remote optical sensor system is an internal research project being conducted by the Air Force Research Laboratory Directed Energy Directorate, Active Remote Sensing Branch. The objective of the project is to develop a new long-range standoff spectral sensor that takes advantage of the enhanced performance capabilities coherent detection can provide. Emphasis of the development is on a low cost, compact, and rugged active sensor exclusively designed for heterodyne detection using the differential absorption lidar technique. State of the art technologies in waveguide laser construction and acousto- optics make feasible the next generation of lasers capable of supporting coherent lidar system requirements. Issues addressed as part of the development include optoelectronic engineering of a low cost rugged system, and fast data throughput for real time chemical concentration measurements. All hardware used in this sensor are off-the- shelf items, so only minor hardware modifications were required for the system as it stands. This paper describes a high-speed heterodyne detection CO2 DIAL system that employs a wavelength agile, acousto-optically tuned local oscillator in the receiver. Sample experimental data collected in a controlled environment are presented as well. Chemical detection using 12 wavelengths at 200 pulses per second has been demonstrated. Initial progress on experiments to make a direct, simultaneous comparison of heterodyne and direct detection DIAL systems will also be described.

Probing Lewis Acid-Base Interactions with Born-Oppenheimer Molecular Dynamics: The Electronic Absorption Spectrum of p-Nitroaniline in Supercritical CO2.

PubMed

Cabral, Benedito J Costa; Rivelino, Roberto; Coutinho, Kaline; Canuto, Sylvio

2015-07-02

The structure and dynamics of p-nitroaniline (PNA) in supercritical CO2 (scCO2) at T = 315 K and ρ = 0.81 g cm(-3) are investigated by carrying out Born-Oppenheimer molecular dynamics, and the electronic absorption spectrum in scCO2 is determined by time dependent density functional theory. The structure of the PNA-scCO2 solution illustrates the role played by Lewis acid-base (LA-LB) interactions. In comparison with isolated PNA, the ν(N-O) symmetric and asymmetric stretching modes of PNA in scCO2 are red-shifted by -17 and -29 cm(-1), respectively. The maximum of the charge transfer (CT) absorption band of PNA in scSCO2 is at 3.9 eV, and the predicted red-shift of the π → π* electronic transition relative to the isolated gas-phase PNA molecule reproduces the experimental value of -0.35 eV. An analysis of the relationship between geometry distortions and excitation energies of PNA in scCO2 shows that the π → π* CT transition is very sensitive to changes of the N-O bond distance, strongly indicating a correlation between vibrational and electronic solvatochromism driven by LA-LB interactions. Despite the importance of LA-LB interactions to explain the solvation of PNA in scCO2, the red-shift of the CT band is mainly determined by electrostatic interactions.

Optical absorption and thermal stability study of Cu doped NiO nanoparticles

NASA Astrophysics Data System (ADS)

Varunkumar, K.; Ethiraj, Anita Sagadevan; Kechiantz, Ara

2018-05-01

This work reports variation of Cu doping concentration in NiO nanoparticles (NiO:Cu NPs) synthesized via chemical co-precipitation from solution by using NiCl2.6H2O as precursor, CuSO4.5H2O as dopant and NaOH as surfactant. We studied optical and thermal stability of prepared NiO:Cu NPs by UV-Vis absorbance, Diffuse Reflectance Spectroscopy (DRS), Atomic Absorption Spectroscopy (AAS), and Thermo Gravimetric/Differential Scanning Calorimetry (TGA/DSC) analyses. Optical absorption data of NiO:Cu NPs indicated strong absorption peaks shifted towards blue with respect to the peak of undoped NiO NPs due to quantum confinement effect. The bandgap estimated via Tauc plot first increased from 3.32eV (undoped NiO NPs) to 3.37 eV (8 at % of Cu in NiO NPs) and further increase of Cu doping to 10 at% reduced the bandgap to 3.35 eV. Such behavior of the bandgap clearly indicates that the size of NiO NPs first reduces with Cu doping up to 8 at % and then increases with further Cu doping to 10 at %. This behavior of reduction in particle size with increased doping can be attributed to the dislocation density and microstrain developed in NiO:Cu NPs. Thermal stability analysis demonstrated that in addition undoped NiO NPs, all NiO:Cu nanoparticle samples exhibited good thermal stability.

Ultra-violet and visible absorption characterization of explosives by differential reflectometry.

PubMed

Dubroca, Thierry; Moyant, Kyle; Hummel, Rolf E

2013-03-15

This study presents some optical properties of TNT (2,4,6-trinitrotoluene), RDX, HMX and tetryl, specifically their absorption spectra as a function of concentration in various solvents in the ultraviolet and visible portion of the electromagnetic spectrum. We utilize a standoff explosives detection method, called differential reflectometry (DR). TNT was diluted in six different solvents (acetone, acetonitrile, ethanol, ethyl acetate, methanol, and toluene), which allowed for a direct comparison of absorption features over a wide range of concentrations. A line-shape analysis was adopted with great accuracy (R(2)>0.99) to model the absorption features of TNT in differential reflectivity spectra. We observed a blue shift in the pertinent absorption band with decreasing TNT concentration for all solvents. Moreover, using this technique, it was found that for all utilized solvents the concentration of TNT as well as of RDX, HMX, and tetryl, measured as a function of the transition wavelength of the ultra-violet absorption edge in differential reflectivity spectra shows three distinct regions. A model is presented to explain this behavior which is based on intermolecular hydrogen bonding of explosives molecules with themselves (or lack thereof) at different concentrations. Other intermolecular forces such as dipole-dipole interactions, London dispersion forces and π-stacking contribute to slight variations in the resulting spectra, which were determined to be rather insignificant in comparison to hydrogen bonding. The results are aimed towards a better understanding of the DR spectra of explosives energetic materials. Copyright © 2012 Elsevier B.V. All rights reserved.

Enhanced microwave absorbing performance of CoNi alloy nanoparticles anchored on a spherical carbon monolith.

PubMed

Li, Na; Hu, Changwen; Cao, Minhua

2013-05-28

CoNi alloy nanoparticles anchored on a spherical carbon monolith (CoNi-C) were prepared by a solvothermal route and subsequent heat treatment without any templates. Their permittivity and permeability behaviors were studied in the frequency range of 2-18 GHz. The CoNi-C composites showed the best microwave absorbing performances compared to those of Co-C and Ni-C. The maximum reflection loss of the CoNi-C nanocomposites can reach -50.2 dB at 7.7 GHz with samples of 4 mm in thickness, better than that of the Ni-C composites, while the Co-C composites showed almost no absorption at all. The absorption mechanism of the three absorbents was also discussed.

COMPARISON OF SODIUM AND POTASSIUM CARBONATES AS LITHIUM ZIRCONATE MODIFIERS FOR HIGH-TEMPERATURE CARBON DIOXIDE CAPTURE FROM BIOMASS-DERIVED SYNTHESIS GAS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Olstad, J.L.; Phillips, S.D.

2009-01-01

The process of gasifi cation converts biomass into synthesis gas (syngas), which can be used to produce biofuels. Solid-phase sorbents were investigated for the removal of CO2 from a N2/CO2 gas stream using a CO2 concentration similar to that found in a biomass gasifi cation process. During the gasifying process, large amounts of carbon dioxide (CO2) are created along with the syngas. The produced CO2 must be removed before the syngas can be used for fuel synthesis and to avoid the possible formation of unwanted byproducts. A thermogravimetric analyzer was used to test the CO2 absorption rates of sorbents composedmore » of lithium zirconate (Li2ZrO3), as well as mixtures of Li2ZrO3 with potassium carbonate (K2CO3) and sodium carbonate (Na2CO3). The experimental results show that Li2ZrO3 has a low absorption rate, but sorbents containing combinations of Li2ZrO3 and the K2CO3 and Na2CO3 additives have high uptake rates. Using different proportions of K2CO3 and Na2CO3 produces varying uptake rates, so an optimization experiment was performed to obtain an improved sorbent. The CO2 absorption and regeneration stability of the solid-phase sorbents were also examined. A sorbent composed of Li2ZrO3 and 12.1 weight % Na2CO3 was shown to be stable, based on the consistent CO2 uptake rates. Sorbents prepared with Li2ZrO3, 17.6 weight % K2CO3 and 18.1 weight % Na2CO3 showed instability during regeneration cycles in air at 800 °C. Sorbent stability improved during regeneration cycles at 700 °C. Further testing of the Li2ZrO3 sorbent under actual syngas conditions, including higher pressure and composition, should be done. Once the optimum sorbent has been found, a suitable support will be needed to use the sorbent in an actual reactor.« less

Effects of Radiative Emission and Absorption on the Propagation and Extinction of Premixed Gas Flames

NASA Technical Reports Server (NTRS)

Ju, Yiguang; Masuya, Goro; Ronney, Paul D.

1998-01-01

Premixed gas flames in mixtures of CH4, O2, N2, and CO2 were studied numerically using detailed chemical and radiative emission-absorption models to establish the conditions for which radiatively induced extinction limits may exist independent of the system dimensions. It was found that reabsorption of emitted radiation led to substantially higher burning velocities and wider extinction limits than calculations using optically thin radiation models, particularly when CO2, a strong absorber, is present in the unburned gas, Two heat loss mechanisms that lead to flammability limits even with reabsorption were identified. One is that for dry hydrocarbon-air mixtures, because of the differences in the absorption spectra of H2O and CO2, most of the radiation from product H2O that is emitted in the upstream direction cannot be absorbed by the reactants. The second is that the emission spectrum Of CO2 is broader at flame temperatures than ambient temperature: thus, some radiation emitted near the flame front cannot be absorbed by the reactants even when they are seeded with CO2 Via both mechanisms, some net upstream heat loss due to radiation will always occur, leading to extinction of sufficiently weak mixtures. Downstream loss has practically no influence. Comparison with experiment demonstrates the importance of reabsorption in CO2 diluted mixtures. It is concluded that fundamental flammability limits can exist due to radiative heat loss, but these limits are strongly dependent on the emission-absorption spectra of the reactant and product -gases and their temperature dependence and cannot be predicted using gray-gas or optically thin model parameters. Applications to practical flames at high pressure, in large combustion chambers, and with exhaust-gas or flue-gas recirculation are discussed.

Organic molecules and nanoparticles in inorganic crystals: Vitamin C in CaCO3 as an ultraviolet absorber

NASA Astrophysics Data System (ADS)

Sato, H.; Ikeya, M.

2004-03-01

Organic molecules and nanoparticles embedded in inorganic crystalline lattices have been studied to add different properties and functions to composite materials. Calcium carbonate was precipitated by dropping an aqueous solution of CaCl2 into that of Na2CO3 containing dissolved vitamin C (ascorbic acid). The optical absorption ascribed to divalent ascorbate anions in the lattice was observed in the ultraviolet B (wavelength: 280-315 nm) region, while solid vitamin C exhibited absorption in the ultraviolet C (100-280 nm) region. The divalent ascorbate anion is only stable in CaCO3 due to the absence of oxygen molecules. Doping CaCO3 with nanoparticles of ZnO also enhanced the absorption in the ultraviolet A (315-380 nm) region. These composite materials are suggested for use as UV absorbers.

Activity and stability of immobilized carbonic anhydrase for promoting CO2 absorption into a carbonate solution for post-combustion CO2 capture

USGS Publications Warehouse

Zhang, S.; Zhang, Z.; Lu, Y.; Rostam-Abadi, M.; Jones, A.

2011-01-01

An Integrated Vacuum Carbonate Absorption Process (IVCAP) currently under development could significantly reduce the energy consumed when capturing CO2 from the flue gases of coal-fired power plants. The biocatalyst carbonic anhydrase (CA) has been found to effectively promote the absorption of CO2 into the potassium carbonate solution that would be used in the IVCAP. Two CA enzymes were immobilized onto three selected support materials having different pore structures. The thermal stability of the immobilized CA enzymes was significantly greater than their free counterparts. For example, the immobilized enzymes retained at least 60% of their initial activities after 90days at 50??C compared to about 30% for their free counterparts under the same conditions. The immobilized CA also had significantly improved resistance to concentrations of sulfate (0.4M), nitrate (0.05M) and chloride (0.3M) typically found in flue gas scrubbing liquids than their free counterparts. ?? 2011 Elsevier Ltd.

Fumarole/plume and diffuse CO2 emission from Sierra Negra caldera, Galapagos archipelago

NASA Astrophysics Data System (ADS)

Padrón, Eleazar; Hernández, Pedro A.; Pérez, Nemesio M.; Toulkeridis, Theofilos; Melián, Gladys; Barrancos, José; Virgili, Giorgio; Sumino, Hirochika; Notsu, Kenji

2012-08-01

Measurements of visible and diffuse gas emission were conducted in 2006 at the summit of Sierra Negra volcano, Galapagos, with the aim to better characterize degassing after the 2005 eruption. A total SO2 emission of 11 ± 2 t day-1 was derived from miniature differential optical absorption spectrometer (mini-DOAS) ground-based measurements of the plume emanating from the Mini Azufral fumarolic area, the most important site of visible degassing at Sierra Negra volcano. Using a portable multigas system, the H2S/SO2, CO2/SO2, and H2O/SO2 molar ratios in the Mina Azufral plume emissions were found to be 0.41, 52.2, and 867.9, respectively. The corresponding H2O, CO2, and H2S emission rates were 562, 394, and 3 t day-1, respectively. The total output of diffuse CO2 emissions from the summit of Sierra Negra volcano was 990 ± 85 t day-1, with 605 t day-1 being released by a deep source. The diffuse-to-plume CO2 emission ratio was about 1.5. Mina Azufral fumaroles released gasses containing 73.6 mol% of H2O; the main noncondensable components amounted to 97.4 mol% CO2, 1.5 mol% SO2, 0.6 mol% H2S, and 0.35 mol% N2. The higher H2S/SO2 ratio values found in 2006 as compared to those reported before the 2005 eruption reveal a significant hydrothermal contribution to the fumarolic emissions. 3He/4He ratios measured at Mina Azufral fumarolic discharges showed values of 17.88 ± 0.25 R A , indicating a mid-ocean ridge basalts (MORB) and a Galapagos plume contribution of 53 and 47 %, respectively.

Microwave electromagnetic and absorption properties of SiO2/C core/shell composites plated with metal cobalt

NASA Astrophysics Data System (ADS)

Shen, Guozhu; Fang, Xumin; Wu, Hongyan; Wei, Hongyu; Li, Jingfa; Li, Kaipeng; Mei, Buqing; Xu, Yewen

2017-04-01

A facile method has been developed to fabricate magnetic core/shell SiO2/C/Co sub-microspheres via the pyrolysis of SiO2/PANI (polyaniline) and electroless plating method. The electromagnetic parameters of these SiO2/C and SiO2/C/Co composites were measured and the microwave reflection loss properties were evaluated in the frequency range of 2-18 GHz. The results show that the dielectric loss of SiO2/C composite increases with the increase of carbonization temperature and the magnetic loss enhances due to the deposition of cobalt on the SiO2/C sub-microspheres. The reflection loss results exhibit that the microwave absorption properties of the SiO2/C/Co composites are more excellent than those of SiO2/C composites for each thickness. The maximum effective absorption bandwidth (reflection loss ≤ -10 dB) arrives at 5.0 GHz (13.0-18 GHz) for SiO2/C/Co composite with 1.5 mm of thickness and the minimum reflection loss value is -24.0 dB at 5.0 GHz with 4.0 mm of thickness. The microwave loss mechanism of the SiO2/C/Co composites was also discussed in this paper.

Comparative study of elastic electron collisions on the isoelectronic SiN{sub 2}, SiCO, and CSiO radicals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fujimoto, M. M.; Michelin, S. E.; Mazon, K. T.

2007-07-15

We report a theoretical study of elastic electron collisions on three isoelectronic free radicals, namely, SiNN, SiCO, and CSiO. More specifically, differential, integral, and momentum-transfer cross sections are calculated and reported in the (1-100) eV energy range. Calculations are performed at the static-exchange-polarization-absorption level of approximation. A combination of the iterative Schwinger variational method and the distorted-wave approximation is used to solve the scattering equations. Our study reveals that the calculated cross sections for the e{sup -}-SiNN and e{sup -}-SiCO collisions are very similar even at incident energies as low as 3 eV. Strong isomeric effects are also observed inmore » the calculated cross sections for e{sup -}-CSiO and e{sup -}-SiCO collisions, particularly at incident energies below 20 eV. It is believed that the position of the silicon atom being at the center or extremity of the molecules may exert important influence on the calculated cross sections.« less

Electronic states in oxidized NaxCoO2 as revealed by X-ray absorption spectroscopy coupled with ab initio calculation

NASA Astrophysics Data System (ADS)

Niwa, Hideharu; Higashiyama, Kazuyuki; Amaha, Kaoru; Kobayashi, Wataru; Moritomo, Yutaka

2018-04-01

Layered cobalt oxides are promising cathode materials for sodium ion secondary batteries (SIBs). By combined study of the X-ray absorption spectroscopy (XAS) around the O K-edge and ab initio calculation, we investigated the electronic state of the NaxCoO2 with different oxidization state, i.e, in O3-Na0.91CoO2 (CoO2-0.91) and P2-Na0.66CoO2 (CoO2-0.66). The O K-edge spectra in the pre-edge (529-536 eV) region shows significant change with oxidization of NaxCoO2. In O3-Na0.91CoO2, the spectra shows an intense band (B band) at 531 eV. In P2-Na0.66CoO2, the spectral weight of the B band increases and a new band (A band) appears at 530 eV. These spectral changes are qualitatively reproduced by the calculated partial density of states (pDOSs) of O3-NaCoO2 and P2-Na1/2CoO2. These results indicate that the electrons are partially removed from the O 2p state with oxidization of NaxCoO2.

Active chemisorption sites in functionalized ionic liquids for carbon capture.

PubMed

Cui, Guokai; Wang, Jianji; Zhang, Suojiang

2016-07-25

Development of novel technologies for the efficient and reversible capture of CO2 is highly desired. In the last decade, CO2 capture using ionic liquids has attracted intensive attention from both academia and industry, and has been recognized as a very promising technology. Recently, a new approach has been developed for highly efficient capture of CO2 by site-containing ionic liquids through chemical interaction. This perspective review focuses on the recent advances in the chemical absorption of CO2 using site-containing ionic liquids, such as amino-based ionic liquids, azolate ionic liquids, phenolate ionic liquids, dual-functionalized ionic liquids, pyridine-containing ionic liquids and so on. Other site-containing liquid absorbents such as amine-based solutions, switchable solvents, and functionalized ionic liquid-amine blends are also investigated. Strategies have been discussed for how to activate the existent reactive sites and develop novel reactive sites by physical and chemical methods to enhance CO2 absorption capacity and reduce absorption enthalpy. The carbon capture mechanisms of these site-containing liquid absorbents are also presented. Particular attention has been paid to the latest progress in CO2 capture in multiple-site interactions by amino-free anion-functionalized ionic liquids. In the last section, future directions and prospects for carbon capture by site-containing ionic liquids are outlined.

Military Utility of Multispectral and Hyperspectral Sensors

DTIC Science & Technology

1994-11-01

Resolution) ........ 5-12 5-2. Actual and Modeled Target and Conifer Background Signatures. (a) In the MWIR and (b) in the LW IR...absorption in CO2 at 2.7, 4.2, and 15 Pm, and absorption in silicon dioxide between 8.5 and 10 pm. 2.4 DIRECTIONAL REFLECTANCE, BIDIRECTIONAL...3.39 pm), Nd:YAG (1.06 pm), and CO2 (10.6 pm or 5.3 gm doubled). With a typical goniometric facility, a sample is mounted on a 3 axis platform so that

In vitro enzymic hydrolysis of chlorogenic acids in coffee.

PubMed

da Encarnação, Joana Amarante; Farrell, Tracy L; Ryder, Alexandra; Kraut, Nicolai U; Williamson, Gary

2015-02-01

Coffee is rich in quinic acid esters of phenolic acids (chlorogenic acids) but also contains some free phenolic acids. A proportion of phenolic acids appear in the blood rapidly after coffee consumption due to absorption in the small intestine. We investigated in vitro whether this appearance could potentially be derived from free phenolic acids in instant coffee or from hydrolysis of chlorogenic acids by pancreatic or brush border enzymes. We quantified six free phenolic acids in instant coffees using HPLC-DAD-mass spectrometry. The highest was caffeic acid, but all were present at low levels compared to the chlorogenic acids. Roasting and decaffeination significantly reduced free phenolic acid content. We estimated, using pharmacokinetic modelling with previously published data, that the contribution of these compounds to small intestinal absorption is minimal. Hydrolysis of certain chlorogenic acids was observed with human-differentiated Caco-2 cell monolayers and with porcine pancreatin, which showed maximal rates on 3- and 5-O-caffeoylquinic acids, respectively. The amounts of certain free phenolic acids in coffee could only minimally account for small intestinal absorption based on modelling. The hydrolysis of caffeoylquinic, but not feruloylquinic acids, by enterocyte and pancreatic esterases is potentially a contributing mechanism to small intestinal absorption. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

COMET: a planned airborne mission to simultaneously measure CO2 and CH4 columns using airborne remote sensing and in-situ techniques

NASA Astrophysics Data System (ADS)

Fix, A.; Amediek, A.; Büdenbender, C.; Ehret, G.; Wirth, M.; Quatrevalet, M.; Rapp, M.; Gerilowski, K.; Bovensmann, H.; Gerbig, C.; Pfeilsticker, K.; Zöger, M.; Giez, A.

2013-12-01

To better predict future trends in the cycles of the most important anthropogenic greenhouse gases, CO2 and CH4, there is a need to measure and understand their distribution and variation on various scales. To address these requirements it is envisaged to deploy a suite of state-of-the-art airborne instruments that will be capable to simultaneously measure the column averaged dry-air mixing ratios (XGHG) of both greenhouse gases along the flight path. As the measurement platform serves the research aircraft HALO, a modified Gulfstream G550, operated by DLR. This activity is dubbed CoMet (CO2 and Methane Mission). The instrument package of CoMet will consist of active and passive remote sensors as well as in-situ instruments to complement the column measurements by highly-resolved profile information. As an active remote sensing instrument CHARM-F, the integrated-path differential absorption lidar currently under development at DLR, will provide both, XCO2 and XCH4, below flight altitude. The lidar instrument will be complemented by MAMAP which is a NIR/SWIR absorption spectrometer developed by University of Bremen and which is also capable to derive XCH4 and XCO2. As an additional passive instrument, mini-DOAS operated by University of Heidelberg will contribute with additional context information about the investigated air masses. In order to compare the remote sensing instruments with integrated profile information, in-situ instrumentation is indispensable. The in-situ package will therefore comprise wavelength-scanned Cavity-Ring-Down Spectroscopy (CRDS) for the detection of CO2, CH4, CO and H2O and a flask sampler for collection of atmospheric samples and subsequent laboratory analysis. Furthermore, the BAsic HALO Measurement And Sensor System (BAHAMAS) will provide an accurate set of meteorological and aircraft state parameters for each scientific flight. Within the frame of the first CoMet mission scheduled for the 2015 timeframe it is planned to concentrate on small to sub-continental scale variations of the greenhouse gases. This does not only allow to identify local emission sources of GHGs, but also opens up the opportunity to use important remote sensing and in-situ data information for the inverse modeling approach for regional budgeting. CoMet is also targeting at providing a validation platform of future spaceborne GHG missions in particular the upcoming French-German methane mission MERLIN. CHARM-F was devised as an airborne demonstrator for MERLIN, and, as such will be a key instrument for MERLIN validation.

Accurate measurements of carbon monoxide in humid air using the cavity ring-down spectroscopy (CRDS) technique

NASA Astrophysics Data System (ADS)

Chen, H.; Karion, A.; Rella, C. W.; Winderlich, J.; Gerbig, C.; Filges, A.; Newberger, T.; Sweeney, C.; Tans, P. P.

2012-09-01

Accurate measurements of carbon monoxide (CO) in humid air have been made using the cavity ring-down spectroscopy (CRDS) technique. The measurements of CO mole fractions are determined from the strength of its spectral absorption in the near infrared region (∼1.57 μm) after removing interferences from adjacent carbon dioxide (CO2) and water vapor (H2O) absorption lines. Water correction functions that account for the dilution and pressure-broadening effects as well as absorption line interferences from adjacent CO2 and H2O lines have been derived for CO2 mole fractions between 360-390 ppm. The line interference corrections are independent of CO mole fractions. The dependence of the line interference correction on CO2 abundance is estimated to be approximately -0.3 ppb/100 ppm CO2 for dry mole fractions of CO. Comparisons of water correction functions from different analyzers of the same type show significant differences, making it necessary to perform instrument-specific water tests for each individual analyzer. The CRDS analyzer was flown on an aircraft in Alaska from April to November in 2011, and the accuracy of the CO measurements by the CRDS analyzer has been validated against discrete NOAA/ESRL flask sample measurements made on board the same aircraft, with a mean difference between integrated in situ and flask measurements of -0.6 ppb and a standard deviation of 2.8 ppb. Preliminary testing of CRDS instrumentation that employs new spectroscopic analysis (available since the beginning of 2012) indicates a smaller water vapor dependence than the models discussed here, but more work is necessary to fully validate the performance. The CRDS technique provides an accurate and low-maintenance method of monitoring the atmospheric dry mole fractions of CO in humid air streams.

Properties of CoO doped in Glasses Prepared from Rice Hush Fly Ash in Thailand

NASA Astrophysics Data System (ADS)

Ruangtaweep, Y.; Kaewkhao, J.; Kirdsiri, K.; Kedkaew, C.; Limsuwan, P.

2011-10-01

In this work, properties of glass from local rice husk ash (RHA) in Thailand have been investigated. RHA was sintered in different temperature. Compositions and phases of RHA were analyzed by energy dispersive x-ray fluorescence spectrometer (EDXRF) and X-ray diffractometer (XRD). The glasses were melt from RHA in formula 20 Na2O : 1.0 Al2O3 : 13 B2O3 : 6.3 CaO : 0.2 Sb2O3 : 4.5 BaO : 55SiO2 (using RHA as a SiO2 source) The density values of all RHA glasses are comparable and larger than glass from pure SiO2 under same glass formula and preparing condition. These results are corresponding with refractive index values. The RHA glasses showing colorless with absorption edge in ultraviolet region were obtained. The dark blue color glasses were melted from RHA with different CoO concentration. From this part, not found to be the relation of density and refractive index of glass with CoO concentration in glass matrix. From absorption spectra, the absorption peak were appeared around 600 nm, and peak intensity are increased, with increase CoO, correspond to 4A2(4F) → 4T1(4P) state of Co2+ in tetrahedral symmetry.

The Influence of Trace Gases Absorption on Differential Ring Cross Sections

NASA Astrophysics Data System (ADS)

Han, Dong; Zhao, Keyi

2017-04-01

The Ring effect refers to the filling in of Fraunhofer lines, which is known as solar absorption lines, caused almost entirely by rotational Raman scattering. The rotational Raman scattering by N2 and O2 in the atmosphere is the main factor that leads to Ring effect. The Ring effect is one significant limitation to the accuracy of the retrieval of trace gas constituents in atmosphere, while using satellite data with Differential Optical Absorption Spectroscopy technique. In this study, firstly the solar spectrum is convolved with rotational Raman cross sections of atmosphere, which is calculated with rotational Raman cross sections of N2 and O2, divided by the original solar spectrum, with a cubic polynomial subtracted off, to create differential Ring spectrum Ring1. Secondly, the Ring effect for pure Raman scattering of the Fraunhofer spectrum plus the contribution from interference by terrestrial absorption which always comes from a kind of trace gas (e.g., O3) are derived. To allow for more generality, the optically thin term as well as the next term in the expansion for the Beer-Lambert law are calculated.Ring1, Ring2, and Ring3are the Fraunhofer only, 1st terrestrial correction, and 2nd terrestrial correction for DOAS fitting.

Mass Spectrometry Imaging proves differential absorption profiles of well-characterised permeability markers along the crypt-villus axis.

PubMed

Nilsson, Anna; Peric, Alexandra; Strimfors, Marie; Goodwin, Richard J A; Hayes, Martin A; Andrén, Per E; Hilgendorf, Constanze

2017-07-25

Knowledge about the region-specific absorption profiles from the gastrointestinal tract of orally administered drugs is a critical factor guiding dosage form selection in drug development. We have used a novel approach to study three well-characterized permeability and absorption marker drugs in the intestine. Propranolol and metoprolol (highly permeable compounds) and atenolol (low-moderate permeability compound) were orally co-administered to rats. The site of drug absorption was revealed by high spatial resolution matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI) and complemented by quantitative measurement of drug concentration in tissue homogenates. MALDI-MSI identified endogenous molecular markers that illustrated the villi structures and confirmed the different absorption sites assigned to histological landmarks for the three drugs. Propranolol and metoprolol showed a rapid absorption and shorter transit distance in contrast to atenolol, which was absorbed more slowly from more distal sites. This study provides novel insights into site specific absorption for each of the compounds along the crypt-villus axis, as well as confirming a proximal-distal absorption gradient along the intestine. The combined analytical approach allowed the quantification and spatial resolution of drug distribution in the intestine and provided experimental evidence for the suggested absorption behaviour of low and highly permeable compounds.

Transcriptomic response of the Antarctic pteropod Limacina helicina antarctica to ocean acidification.

PubMed

Johnson, Kevin M; Hofmann, Gretchen E

2017-10-23

Ocean acidification (OA), a change in ocean chemistry due to the absorption of atmospheric CO 2 into surface oceans, challenges biogenic calcification in many marine organisms. Ocean acidification is expected to rapidly progress in polar seas, with regions of the Southern Ocean expected to experience severe OA within decades. Biologically, the consequences of OA challenge calcification processes and impose an energetic cost. In order to better characterize the response of a polar calcifier to conditions of OA, we assessed differential gene expression in the Antarctic pteropod, Limacina helicina antarctica. Experimental levels of pCO 2 were chosen to create both contemporary pH conditions, and to mimic future pH expected in OA scenarios. Significant changes in the transcriptome were observed when juvenile L. h. antarctica were acclimated for 21 days to low-pH (7.71), mid-pH (7.9) or high-pH (8.13) conditions. Differential gene expression analysis of individuals maintained in the low-pH treatment identified down-regulation of genes involved in cytoskeletal structure, lipid transport, and metabolism. High pH exposure led to increased expression and enrichment for genes involved in shell formation, calcium ion binding, and DNA binding. Significant differential gene expression was observed in four major cellular and physiological processes: shell formation, the cellular stress response, metabolism, and neural function. Across these functional groups, exposure to conditions that mimic ocean acidification led to rapid suppression of gene expression. Results of this study demonstrated that the transcriptome of the juvenile pteropod, L. h. antarctica, was dynamic and changed in response to different levels of pCO 2 . In a global change context, exposure of L. h. antarctica to the low pH, high pCO 2 OA conditions resulted in a suppression of transcripts for genes involved in key physiological processes: calcification, metabolism, and the cellular stress response. The transcriptomic response at both acute and longer-term acclimation time frames indicated that contemporary L. h. antarctica may not have the physiological plasticity necessary for adaptation to OA conditions expected in future decades. Lastly, the differential gene expression results further support the role of shelled pteropods such as L. h. antarctica as sentinel organisms for the impacts of ocean acidification.

Tunable diode lasers application for fully automated absolute measurements of CO and CO2 concentrations in human breath

NASA Astrophysics Data System (ADS)

Moskalenko, Konstantin L.; Sobolev, Nikolai V.; Adamovskay, Inna A.; Stepanov, Eugene V.; Nadezhdinskii, Alexander I.; McKenna-Lawlor, Susan

1994-01-01

Measurements of carbon monoxide and carbon dioxide concentrations by registration of high resolution absorption spectra are described. A fully automated diode laser system developed to simultaneously measure CO and CO2, with sensitivity for CO up to 50 ppb and CO2 up to 0.1 vol%, is described. Calculation of CO and CO2 concentrations was carried out on the base of a priori date on strength and broadening coefficients of detected absorption lines. Test procedures of such diode laser systems are described. Possible reasons affected on accuracy and reliability of obtained data (e.g., the value of diode lasers spontaneous radiation, the stability of CO content in a cell, etc.) for absolute and relative calibration procedure are discussed. The physiological level of CO concentration in the breath of non smokers and smokers under different ambient conditions of CO concentrations in the atmosphere (in Moscow and in Maynooth) are compared. Recent results on statistical studies of the behavior of CO concentrations as a function of breath holding time are represented.

Advanced Intensity-Modulation Continuous-Wave Lidar Techniques for ASCENDS O2 Column Measurements

NASA Technical Reports Server (NTRS)

Campbell, Joel F.; Lin, Bing; Nehrir, Amin R.; Harrison, F. Wallace; Obland, Michael D.; Meadows, Byron

2015-01-01

Global atmospheric carbon dioxide (CO2) measurements for the NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) space mission are critical for improving our understanding of global CO2 sources and sinks. Advanced Intensity- Modulated Continuous-Wave (IM-CW) lidar techniques are investigated as a means of facilitating CO2 measurements from space to meet the ASCENDS measurement requirements. In recent numerical, laboratory and flight experiments we have successfully used the Binary Phase Shift Keying (BPSK) modulation technique to uniquely discriminate surface lidar returns from intermediate aerosol and cloud contamination. We demonstrate the utility of BPSK to eliminate sidelobes in the range profile as a means of making Integrated Path Differential Absorption (IPDA) column CO2 measurements in the presence of optically thin clouds, thereby eliminating the need to correct for sidelobe bias errors caused by the clouds. Furthermore, high accuracy and precision ranging to the surface as well as to the top of intermediate cloud layers, which is a requirement for the inversion of column CO2 number density measurements to column CO2 mixing ratios, has been demonstrated using new hyperfine interpolation techniques that takes advantage of the periodicity of the modulation waveforms. This approach works well for both BPSK and linear swept-frequency modulation techniques. The BPSK technique under investigation has excellent auto-correlation properties while possessing a finite bandwidth. A comparison of BPSK and linear swept-frequency is also discussed in this paper. These results are extended to include Richardson-Lucy deconvolution techniques to extend the resolution of the lidar beyond that implied by limit of the bandwidth of the modulation, where it is shown useful for making tree canopy measurements.

Development of Double and Triple-Pulsed 2-micron IPDA Lidars for Column CO2 Measurements

NASA Technical Reports Server (NTRS)

Singh, Upendra N.; Yu, Jirong; Petros, Mulugeta; Refaat, Tamer F.; Remus, Ruben G.; Reithmaier, Karl

2015-01-01

Carbon dioxide (CO2) is an important greenhouse gas that significantly contributes to the carbon cycle and globalradiation budget on Earth. CO2 role on Earth’s climate is complicated due to different interactions with various climatecomponents that include the atmosphere, the biosphere and the hydrosphere. Although extensive worldwide efforts formonitoring atmospheric CO2 through various techniques, including in-situ and passive sensors, are taking place highuncertainties exist in quantifying CO2 sources and sinks. These uncertainties are mainly due to insufficient spatial andtemporal mapping of the gas. Therefore it is required to have more rapid and accurate CO2 monitoring with higheruniform coverage and higher resolution. CO2 DIAL operating in the 2-µm band offer better near-surface CO2measurement sensitivity due to the intrinsically stronger absorption lines. For more than 15 years, NASA LangleyResearch Center (LaRC) contributed in developing several 2-?m CO2 DIAL systems and technologies. This paperfocuses on the current development of the airborne double-pulsed and triple-pulsed 2-?m CO2 integrated pathdifferential absorption (IPDA) lidar system at NASA LaRC. This includes the IPDA system development andintegration. Results from ground and airborne CO2 IPDA testing will be presented. The potential of scaling suchtechnology to a space mission will be addressed.

Chemical absorption and CO2 biofixation via the cultivation of Spirulina in semicontinuous mode with nutrient recycle.

PubMed

da Rosa, Gabriel Martins; Moraes, Luiza; Cardias, Bruna Barcelos; de Souza, Michele da Rosa Andrade Zimmermann; Costa, Jorge Alberto Vieira

2015-09-01

The chemical absorption of carbon dioxide (CO2) is a technique used for the mitigation of the greenhouse effect. However, this process consumes high amounts of energy to regenerate the absorbent and to separate the CO2. CO2 removal by microalgae can be obtained via the photosynthesis process. The objective of this study was to investigate the cultivation and the macromolecules production by Spirulina sp. LEB 18 with the addition of monoethanolamine (MEA) and CO2. In the cultivation with MEA, were obtained higher results of specific growth rate, biomass productivity, CO2 biofixation, CO2 use efficiency, and lower generation time. Besides this, the carbohydrate concentration obtained at the end of this assay was approximately 96.0% higher than the control assay. Therefore, Spirulina can be produced using medium recycle and the addition of MEA, thereby promoting the reduction of CO2 emissions and showing potential for areas that require higher concentrations of carbohydrates, such as in bioethanol production. Copyright © 2015 Elsevier Ltd. All rights reserved.

Accurate measurements of carbon monoxide in humid air using the cavity ring-down spectroscopy (CRDS) technique

NASA Astrophysics Data System (ADS)

Chen, H.; Karion, A.; Rella, C. W.; Winderlich, J.; Gerbig, C.; Filges, A.; Newberger, T.; Sweeney, C.; Tans, P. P.

2013-04-01

Accurate measurements of carbon monoxide (CO) in humid air have been made using the cavity ring-down spectroscopy (CRDS) technique. The measurements of CO mole fractions are determined from the strength of its spectral absorption in the near-infrared region (~1.57 μm) after removing interferences from adjacent carbon dioxide (CO2) and water vapor (H2O) absorption lines. Water correction functions that account for the dilution and pressure-broadening effects as well as absorption line interferences from adjacent CO2 and H2O lines have been derived for CO2 mole fractions between 360-390 ppm and for reported H2O mole fractions between 0-4%. The line interference corrections are independent of CO mole fractions. The dependence of the line interference correction on CO2 abundance is estimated to be approximately -0.3 ppb/100 ppm CO2 for dry mole fractions of CO. Comparisons of water correction functions from different analyzers of the same type show significant differences, making it necessary to perform instrument-specific water tests for each individual analyzer. The CRDS analyzer was flown on an aircraft in Alaska from April to November in 2011, and the accuracy of the CO measurements by the CRDS analyzer has been validated against discrete NOAA/ESRL flask sample measurements made on board the same aircraft, with a mean difference between integrated in situ and flask measurements of -0.6 ppb and a standard deviation of 2.8 ppb. Preliminary testing of CRDS instrumentation that employs improved spectroscopic model functions for CO2, H2O, and CO to fit the raw spectral data (available since the beginning of 2012) indicates a smaller water vapor dependence than the models discussed here, but more work is necessary to fully validate the performance. The CRDS technique provides an accurate and low-maintenance method of monitoring the atmospheric dry mole fractions of CO in humid air streams.

Co:MgF2 laser ablation of tissue: effect of wavelength on ablation threshold and thermal damage.

PubMed

Schomacker, K T; Domankevitz, Y; Flotte, T J; Deutsch, T F

1991-01-01

The wavelength dependence of the ablation threshold of a variety of tissues has been studied by using a tunable pulsed Co:MgF2 laser to determine how closely it tracks the optical absorption length of water. The Co:MgF2 laser was tuned between 1.81 and 2.14 microns, a wavelength region in which the absorption length varies by a decade. For soft tissues the ablation threshold tracks the optical absorption length; for bone there is little wavelength dependence, consistent with the low water content of bone. Thermal damage vs. wavelength was also studied for cornea and bone. Thermal damage to cornea has a weak wavelength dependence, while that to bone shows little wavelength dependence. Framing-camera pictures of the ablation of both cornea and liver show explosive removal of material, but differ as to the nature of the explosion.

Effect of hydrogen concentration in conventional and IAD coatings on the absorption and laser-induced damage at 10.6 μm

NASA Astrophysics Data System (ADS)

Rahe, Manfred; Ristau, Detlev; Schmidt, Holger

1993-06-01

In this paper, data of single layers of YbF3, BaF2, YF3, and NaF and multilayer coatings produced by conventional thermal evaporation (boat, e-beam) and ion assisted deposition (IAD) are compared. Hydrogen concentration depth profiling was performed using nuclear reaction analysis based on the reaction 1H(15N, (alpha) (gamma) )12C. Absorption was measured with the aid of a laser calorimeter and a cw CO2 laser. A computer-controlled test facility with a TEA CO2 laser was used for determining the 1-on-1 damage thresholds of the coatings. The results point out that the absorption and damage behavior of coatings for the CO2 laser wavelength are related to the total amount of species containing hydrogen. Most of the IAD coatings exhibit a lower hydrogen contamination than conventional thin films.

Method and apparatus for simulating atomospheric absorption of solar energy due to water vapor and CO.sub.2

DOEpatents

Sopori, Bhushan L.

1995-01-01

A method and apparatus for improving the accuracy of the simulation of sunlight reaching the earth's surface includes a relatively small heated chamber having an optical inlet and an optical outlet, the chamber having a cavity that can be filled with a heated stream of CO.sub.2 and water vapor. A simulated beam comprising infrared and near infrared light can be directed through the chamber cavity containing the CO.sub.2 and water vapor, whereby the spectral characteristics of the beam are altered so that the output beam from the chamber contains wavelength bands that accurately replicate atmospheric absorption of solar energy due to atmospheric CO.sub.2 and moisture.

Method and apparatus for simulating atmospheric absorption of solar energy due to water vapor and CO{sub 2}

DOEpatents

Sopori, B.L.

1995-06-20

A method and apparatus for improving the accuracy of the simulation of sunlight reaching the earth`s surface includes a relatively small heated chamber having an optical inlet and an optical outlet, the chamber having a cavity that can be filled with a heated stream of CO{sub 2} and water vapor. A simulated beam comprising infrared and near infrared light can be directed through the chamber cavity containing the CO{sub 2} and water vapor, whereby the spectral characteristics of the beam are altered so that the output beam from the chamber contains wavelength bands that accurately replicate atmospheric absorption of solar energy due to atmospheric CO{sub 2} and moisture. 8 figs.

Atmospheric CO2 Concentration Measurements with Clouds from an Airborne Lidar

NASA Astrophysics Data System (ADS)

Mao, J.; Abshire, J. B.; Kawa, S. R.; Riris, H.; Allan, G. R.; Hasselbrack, W. E.; Numata, K.; Chen, J. R.; Sun, X.; DiGangi, J. P.; Choi, Y.

2017-12-01

Globally distributed atmospheric CO2 concentration measurements with high precision, low bias and full seasonal sampling are crucial to advance carbon cycle sciences. However, two thirds of the Earth's surface is typically covered by clouds, and passive remote sensing approaches from space are limited to cloud-free scenes. NASA Goddard is developing a pulsed, integrated-path differential absorption (IPDA) lidar approach to measure atmospheric column CO2 concentrations, XCO2, from space as a candidate for NASA's ASCENDS mission. Measurements of time-resolved laser backscatter profiles from the atmosphere also allow this technique to estimate XCO2 and range to cloud tops in addition to those to the ground with precise knowledge of the photon path-length. We demonstrate this measurement capability using airborne lidar measurements from summer 2017 ASCENDS airborne science campaign in Alaska. We show retrievals of XCO2 to ground and to a variety of cloud tops. We will also demonstrate how the partial column XCO2 to cloud tops and cloud slicing approach help resolving vertical and horizontal gradient of CO2 in cloudy conditions. The XCO2 retrievals from the lidar are validated against in situ measurements and compared to the Goddard Parameterized Chemistry Transport Model (PCTM) simulations. Adding this measurement capability to the future lidar mission for XCO2 will provide full global and seasonal data coverage and some information about vertical structure of CO2. This unique facility is expected to benefit atmospheric transport process studies, carbon data assimilation in models, and global and regional carbon flux estimation.

Preparation and high-performance microwave absorption of hierarchical dendrite-like Co superstructures self-assembly of nanoflakes

NASA Astrophysics Data System (ADS)

Yu, Miao; Wang, Lirui; Yang, Pingan; Fu, Jie

2017-12-01

Dendritic-like Co superstructures based on the self-assembly of nanoflakes that could efficiently suppress the eddy current were successfully synthesized via a facile, rapid, and energy-saving chemical reduction method. Since crystal structure, size, and special geometrical morphology, magnetism have a vital influence on microwave absorption properties, the as-obtained products were characterized by x-ray diffraction, scanning electron microscopy, vibrating sample magnetometry, and vector network analysis. The prepared dendritic Co possesses abundant secondary branches that extend to the 3D space. Their dimensions, spacing, sheet-like blocks, and high-ordering microstructures all contribute to the penetration, scattering, and attenuation of EM waves. The composites present attractive microwave absorption performances in the X band, as well as in the whole S band (2-4 GHz). This work investigates the mechanism of absorption for the as-obtained Co, offers a promising strategy for the fabrication of hierarchical Co microstructure assemblies by multi-leaf flakes and introduces the application of dendritic-like Co as a highly efficient absorber in the S band and X band.

Delocalization and occupancy effects of 5f orbitals in plutonium intermetallics using L3-edge resonant X-ray emission spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Booth, C. H.; Medling, S. A.; Jiang, Yu

2014-06-24

Although actinide (An) L3 -edge X-ray absorption near-edge structure (XANES) spectroscopy has been very effective in determining An oxidation states in insulating, ionically bonded materials, such as in certain coordination compounds and mineral systems, the technique fails in systems featuring more delocalized 5f orbitals, especially in metals. Recently, actinide L3-edge resonant X-ray emission spec- troscopy (RXES) has been shown to be an effective alternative. This technique is further demonstrated here using a parameterized partial unoccupied density of states method to quantify both occupancy and delocalization of the 5f orbital in ?-Pu, ?-Pu, PuCoGa5 , PuCoIn5 , and PuSb2. These newmore » results, supported by FEFF calculations, highlight the effects of strong correlations on RXES spectra and the technique?s ability to differentiate between f-orbital occupation and delocalization.« less

Fabrication and spectroscopic properties of Co:MgAl2O4 transparent ceramics by the HIP post-treatment

NASA Astrophysics Data System (ADS)

Luo, Wei; Ma, Peng; Xie, Tengfei; Dai, Jiawei; Pan, Yubai; Kou, Huamin; Li, Jiang

2017-07-01

Cobalt-doped magnesium aluminate spinel (Co:MgAl2O4) is one of the most important saturable absorbers for the passive Q-switching of solid-state lasers operating at eye-safe wavelength of 1.5 μm. In this work, highly transparent Co:MgAl2O4 ceramics were fabricated by vacuum sintering combined with hot isostatic pressing (HIP) post-treatment, using the mixture of the commercial spinel and the lab-made Co:MgAl2O4 powder as the raw materials. The densification mechanism of Co:MgAl2O4 transparent ceramics was discussed. The microstructure and optical properties of the samples were investigated. The ground state absorption cross section (σGSA) was calculated from the fitted curve of the absorption coefficient spectrum. The results show that Co:MgAl2O4 ceramics fabricated by vacuum sintering at 1500 °C for 5 h and then HIP post-treatment at 1650 °C for 3 h perform good transparency, whose in-line transmittance exceeds 80% at 2500 nm. Moreover, the ground state absorption cross section of 0.02 at.% Co:MgAl2O4 ceramics is calculated to be 3.35 × 10-19 cm2 at the wavelength of 1540 nm, which is promising for the application to the passive Q-switching of solid-state laser operating in the near infrared region (NIR).

Differential Radiometers Using Fabry-Perot Interferometric Technique for Remote Sensing Determination of Various Atmospheric Trace Gases

NASA Technical Reports Server (NTRS)

Georgieva, E. M.; Heaps, W. S.; Wilson, E. L.

2007-01-01

New type of remote sensing instrument based upon the Fabry-Perot inte rferometric technique has been developed at NASA's Goddard Space Flight Center. Fabry-Perot interferometry (FPI) is a well known, powerful spectroscopic technique and one of its many applications is to be use d to measure greenhouse gases and also some harmful species in the at mosphere. With this technique, absorption of particular species is me asured and related to its concentration. A solid Fabry-Perot etalon is used as a frequency filter to restrict the measurement to particular absorption bands of the gas of interest. With adjusting the thicknes s of the etalon that separation (in frequency) of the transmitted fri nges can be made equal to the almost constant separation of the gas a bsorption lines. By adjusting the temperature of the etalon, which changes the index of refi-action of its material, the transmission fring es can be brought into nearly exact correspondence with absorption li nes of the particular species. With this alignment between absorption lines and fringes, changes in the amount of a species in the atmosph ere strongly affect the amount of light transmitted by the etalon and can be related to gas concentration. The instrument that we have dev eloped detects the absorption of various atmospheric trace gases in d irect or reflected sunlight. Our instrument employing Fabry-Perot interferometer makes use of two features to achieve high sensitivity. The first is high spectral resolution enabling one to match the width of an atmospheric absorption feature by the instrumental band pass. The second is high optical throughput enabled by using multiple spectral lines simultaneously. For any species that one wishes to measure, thi s first feature is available while the use of multiple spectral features can be employed only for species with suitable spectra and freedom from interfering species in the same wavelength region. We have deve loped an instrument for use as ground based, airborne and satellite s ensor for gases such as carbon dioxide (1570 nm), oxygen (762 nm and 768 nm lines sensitive to changes in oxygen pressure and oxygen temper ature) and water vapor (940 nm). Our current goal is to develop an ul tra precise, inexpensive, ground based device suitable for wide deplo yment as a validation instrument for the Orbiting Carbon Observatory (OCO) satellite. We show sensitivity measurements for CO2, 02, and H2 O, compare our measurements to those obtained using other types of sensors and discuss some of the peculiarities that must be addressed in order to provide the very high quality column detection required for solving problems about global distribution of greenhouse gases and cl imatological models. In another area of research we are interested in developing a small-size channel for CO2 capable of doing simultaneous measurements with the AERONET (Aerosol Robotic Network) at NASA, God dard to study the hypothesis that atmospheric aerosols affect the reg ional terrestrial carbon cycle. We present recent data from our groun d based measurements of O2, CO2, H2O and (13)CO2 and discuss extensio n of the technique to new species and applications.

Atmospheric transmission of CO2 laser radiation with application to laser Doppler systems

NASA Technical Reports Server (NTRS)

Murty, S. S. R.

1975-01-01

The molecular absorption coefficients of carbon dioxide, water vapor, and nitrous oxide are calculated at the P16, P18, P20, P22, and P24 lines of the CO2 laser for temperatures from 200 to 300 K and for pressures from 100 to 1100 mb. The temperature variation of the continuum absorption coefficient of water vapor is taken into account semi-empirically from Burch's data. The total absorption coefficient from the present calculations falls within + or - 20 percent of the results of McClatchey and Selby. The transmission loss which the CO2 pulsed laser Doppler system experiences was calculated for flight test conditions for the five P-lines. The total transmission loss is approximately 7 percent higher at the P16 line and 10 percent lower at the P24 line compared to the P20 line. Comparison of the CO2 laser with HF and DF laser transmission reveals the P2(8) line at 3.8 micrometers of the DF laser is much better from the transmission point of view for altitudes below 10 km.

Electronic spectroscopy of HRe(CO) 5: a CASSCF/CASPT2 and TD-DFT study

NASA Astrophysics Data System (ADS)

Bossert, J.; Ben Amor, N.; Strich, A.; Daniel, C.

2001-07-01

The low-lying excited states of HRe(CO) 5 have been calculated at the CASSCF/CASPT2 and TD-DFT level of theory using relativistic effective core potentials (ECP) or ab initio model potentials (AIMP). The theoretical absorption spectrum is compared to the experimental one. Despite the similarity between the experimental absorption spectra of HMn(CO) 5 and HRe(CO) 5 in the UV/visible energy domain it is shown that the assignment differs significantly between the two molecules. The low-lying excited states of HRe(CO) 5 correspond to 5d→π *CO excitations whereas the spectrum of HMn(CO) 5 consists mainly of 3d→3d and 3d→ σ*Mn-H excitations. If the CASPT2 and TD-DFT results are quite comparable for the lowest excited states, the upper part assignment is more problematic with the TD-DFT method.

Enhancing the microwave absorption properties of amorphous CoO nanosheet-coated Co (hexagonal and cubic phases) through interfacial polarizations.

PubMed

Deng, Jiushuai; Li, Shimei; Zhou, Yuanyuan; Liang, Luyang; Zhao, Biao; Zhang, Xi; Zhang, Rui

2018-01-01

Core-shell flower-like composites were successfully prepared by a simple polyol method. These composites were formed by coating dual-phased (face-centered cubic [fcc] and hexagonal close-packed [hcp]) Co with amorphous CoO nanosheets. The microwave absorption properties of the flower-like Co@CoO paraffin composites with various Co@CoO amounts were then investigated. Results showed that the paraffin-based composite containing 70wt% flower-like Co@CoO displayed excellent microwave absorption properties (R E =24.74dB·GHz/mm). The minimum reflection loss of -30.4dB was obtained at 16.1GHz with a small thickness of 1.5mm, and 1.5mm bandwidth reached 4.6GHz (13.4-18GHz) below -10dB (90% microwave absorption). The excellent microwave absorption properties of flower-like Co@CoO are attributed to the synergetic effect between magnetic loss and dielectric loss, and the magnetic loss makes a main contribution to absorption. The core-shell flower-like structures with dual Co phases also contributed to microwave absorption. The amorphous CoO nanosheets were able to generate multiple reflections and exhibit scattering. In addition, the novel absorption mechanism that enhanced interfacial polarization was proposed. This enhancement resulted from the presence of interfaces between the hcp and fcc phases and between the core-shell Co@CoO composites. Copyright © 2017 Elsevier Inc. All rights reserved.

Performance modeling for A-SCOPE: a space-borne lidar measuring atmospheric CO2

NASA Astrophysics Data System (ADS)

Caron, Jérôme; Durand, Yannig; Bezy, Jean-Loup; Meynart, Roland

2009-09-01

A-SCOPE (Advanced Space Carbon and Climate Observation of Planet Earth) has been one of the six candidates for the third cycle of the Earth Explorer Core missions, selected by the European Space Agency (ESA) for assessment studies. Earth Explorer missions focus on the science and research aspects of ESA's Living Planet Programme. A-SCOPE mission aims at observing atmospheric CO2 for a better understanding of the carbon cycle. Knowledge about the spatial distribution of sources and sinks of CO2 with unprecedented accuracy will provide urgently needed information about the global carbon cycle. A-SCOPE mission encompasses a new approach to observe the Earth from space based on an IPDA (Integrated Path Differential Absorption) Lidar. Based on the known principle of a differential measurement technique, the IPDA lidar relies on the measurement of the laser echoes reflected by hard targets as the ground or the top of the vegetation. Such a time-gated technique is a promising way to overcome the sources of systematic errors inherent to passive missions. To be fully exploited, it however translates into stringent instrument requirements and requires a dedicated performance assessment. In this paper, the A-SCOPE instrument concept is first presented, with the aim of summarizing some important outcomes from the industrial assessment studies. After a discussion of the mission requirements and measurement principles, an overview is given about the instrument architecture. Then the instrument performance is reported, together with a detailed discussion about sources of systematic errors, which pose the strongest technical challenges.

Origin of the enhanced exchange bias in polycrystalline-BiFeO3/Co bilayers by X-ray absorption Spectroscopy

NASA Astrophysics Data System (ADS)

Shen, J. D.; Yang, W. B.; Kumar, A.; Zhao, H. H.; Lai, Y. J.; Feng, L. S.; Xu, Q. Y.; Zhang, Y. Q.; Du, J.; Li, Q.

2018-04-01

Polycrystalline-BiFeO3(BFO)/Co bilayers were grown by pulsed laser deposition (PLD) and magnetron sputtering, with fast laser annealing under magnetic field. The enhanced exchange bias (EB) had been found in the BFO/Co bilayers (Appl. Surf. Sci. 367 (2016) 418). In order to reveal the origin of the enhanced EB in the samples, X-ray absorption Spectroscopy (XAS) of Fe 2p, Co 2p and O 1s were performed. The Co 2p XAS indicated the increase of Co oxidation state and the Fe 2p XAS of sample A and B under laser annealing processes showed that crystal field splitting energy decreased and led to the weakening of spin-orbit coupling with the increasing of the laser fluence. It was considered that the appearance of the oxidation state of Co and Fe2+ ions and the existence of the unidirectional anisotropy due to the laser fluence was responsible for the results and also for the enhanced EB.

Temperature sensitivity of differential absorption lidar measurements of water vapor in the 720-nm region

NASA Technical Reports Server (NTRS)

Browell, Edward V.; Ismail, Syed; Grossmann, Benoist E.

1991-01-01

Recently measured properties of water vapor (H2O) absorption lines have been used in calculations to evalute the temperature sensitivity of differential absorption lidar (Dial) H2O measurements. This paper estimates the temperature sensitivity of H2O lines in the 717-733-nm region for both H2O mixing ratio and number density measurements, and discusses the influence of the H2O line ground state energies E-double-prime, the H2O absorption linewidths, the linewidth temperature dependence parameter, and the atmospheric temperature and pressure variations with altitude and location on the temperature sensitivity calculations. Line parameters and temperature sensitivity calculations for 67 H2O lines in the 720-nm band are given which can be directly used in field experiments. Water vapor lines with E-double-prime values in the 100-300/cm range were found to be optimum for Dial measurements of H2O number densities, while E-double-prime values in the 250-500/cm range were found to be optimum for H2O mixing ratio measurements.

CO/H2 Abundance Ratio ≈ 10-4 in a Protoplanetary Disk

NASA Astrophysics Data System (ADS)

France, Kevin; Herczeg, Gregory J.; McJunkin, Matthew; Penton, Steven V.

2014-10-01

The relative abundances of atomic and molecular species in planet-forming disks around young stars provide important constraints on photochemical disk models and provide a baseline for calculating disk masses from measurements of trace species. A knowledge of absolute abundances, those relative to molecular hydrogen (H2), are challenging because of the weak rovibrational transition ladder of H2 and the inability to spatially resolve different emission components within the circumstellar environment. To address both of these issues, we present new contemporaneous measurements of CO and H2 absorption through the "warm molecular layer" of the protoplanetary disk around the Classical T Tauri Star RW Aurigae A. We use a newly commissioned observing mode of the Hubble Space Telescope Cosmic Origins Spectrograph to detect warm H2 absorption in this region for the first time. An analysis of the emission and absorption spectrum of RW Aur shows components from the accretion region near the stellar photosphere, the molecular disk, and several outflow components. The warm H2 and CO absorption lines are consistent with a disk origin. We model the 1092-1117 Å spectrum of RW Aur to derive log10 N(H2) = 19.90+0.33-0.22 cm-2 at T rot(H2) = 440 ± 39 K. The CO A - X bands observed from 1410 to 1520 Å are best fit by log10 N(CO) = 16.1 +0.3-0.5 cm-2 at T rot(CO) = 200+650-125 K. Combining direct measurements of the H I, H2, and CO column densities, we find a molecular fraction in the warm disk surface of f H2 >= 0.47 and derive a molecular abundance ratio of CO/H2 = 1.6+4.7-1.3 × 10-4, both consistent with canonical interstellar dense cloud values. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555.

Compact Laser-Based Sensors for Monitoring and Control of Gas Turbine Combustors

NASA Technical Reports Server (NTRS)

Hanson, Ronald K.; Jeffries, Jay B.

2003-01-01

Research is reported on the development of sensors for gas turbine combustor applications that measure real-time gas temperature using near-infrared water vapor absorption and concentration in the combustor exhaust of trace quantities of pollutant NO and CO using mid-infrared absorption. Gas temperature is extracted from the relative absorption strength of two near-infrared transitions of water vapor. From a survey of the water vapor absorption spectrum, two overtone transitions near 1800 nm were selected that can be rapidly scanned in wavelength by injection current tuning a single DFB diode laser. From the ratio of the absorbances on these selected transitions, a path-integrated gas temperature can be extracted in near-real time. Demonstration measurements with this new temperature sensor showed that combustor instabilities could be identified in the power spectrum of the temperature versus time record. These results suggest that this strategy is extremely promising for gas turbine combustor control applications. Measurements of the concentration of NO and CO in the combustor exhaust are demonstrated with mid-infrared transitions using thermo-electrically cooled, quantum cascade lasers operating near 5.26 and 4.62 microns respectively. Measurements of NO are performed in an insulated exhaust duct of a C2H4-air flame at temperatures of approximately 600 K. CO measurements are performed above a rich H2-air flame seeded with CO2 and cooled with excess N2 to 1150 K. Using a balanced ratiometric detection technique a sensitivity of 0.36 ppm-m was achieved for NO and 0.21 ppm-m for CO. Comparisons between measured and predicted water-vapor and CO2 interference are discussed. The mid-infrared laser quantum cascade laser technology is in its infancy; however, these measurements demonstrate the potential for pollutant monitoring in exhaust gases with mid-IR laser absorption.

Miniaturized Laser Heterodyne Radiometer for Measurements of CO2 in the Atmospheric Column

NASA Technical Reports Server (NTRS)

Wilson, E. L.; Mclinden, M. L.; Miller, J. H.; Allan, G. R.; Lott, L. E.; Melroy, H. R.; Clarke, G. B.

2013-01-01

We have developed a low-cost, miniaturized laser heterodyne radiometer for highly sensitive measurements of carbon dioxide (CO2) in the atmospheric column. In this passive design, sunlight that has undergone absorption by CO2 in the atmosphere is collected and mixed with continuous wave laser light that is step-scanned across the absorption feature centered at 1,573.6 nm. The resulting radio frequency beat signal is collected as a function of laser wavelength, from which the total column mole fraction can be de-convolved. We are expanding this technique to include methane (CH4) and carbon monoxide (CO), and with minor modifications, this technique can be expanded to include species such as water vapor (H2O) and nitrous oxide (N2O).

Measurement of Concentration of CO2 in Atmosphere In Situ Based on TDLAS

NASA Astrophysics Data System (ADS)

Xin, Fengxin; Guo, Jinjia; Chen, Zhen; Liu, Zhishen

2014-11-01

As one of the main greenhouse gases in the atmosphere, CO2 has a significant impact on global climate change and the ecological environment. Because of close relationship between human activities and the CO2 emissions, it is very meaningful of detecting atmospheric CO2 accurately. Based on the technology of tunable diode laser absorption spectroscopy, the wavelength of distributed feedback laser is modulated, Fresnel lens is used as the receiving optical system, which receives the laser-beam reflected by corner reflector, and focuses the receiving laser-beam to the photoelectric detector. The second harmonic signal is received through lock-in amplifier and collected by AD data acquisition card, after that the system is built up. By choosing the infrared absorption line of CO2 at 1.57μm, the system is calibrated by 100% CO2 gas cell. The atmospheric CO2 in situ is measured with long open-path way. Furthermore, the results show that CO2 concentration decreases along time in the morning of day. It is proved that TDLAS technology has many advantages, including fast response, high sensitivity and resolution. This research provides a technique for monitoring secular change of CO2 in atmosphere.

Measurement of Concentration of CO2 in Atmosphere In Situ Based on TDLAS

NASA Astrophysics Data System (ADS)

Xin, Fengxin; Guo, Jinjia; Chen, Zhen; Liu, Zhishen

2014-11-01

As one of the main greenhouse gases in the atmosphere, CO2has a significant impact on global climate change and the ecological environment. Because of close relationship between human activities and the CO2 emissions, it is very meaningful of detecting atmospheric CO2accurately. Based on the technology of tunable diode laser absorption spectroscopy, the wavelength of distributed feedback laser is modulated, Fresnel lens is used as the receiving optical system, which receives the laser-beam reflected by corner reflector, and focuses the receiving laser-beam to the photoelectric detector. The second harmonic signal is received through lock-in amplifier and collected by AD data acquisition card, after that the system is built up.By choosing the infrared absorption line of CO2at 1.57μm, the system is calibrated by 100% CO2 gas cell. The atmospheric CO2 in situ is measured with long open-path way. Furthermore, the results show that CO2 concentration decreases along time in the morning of day. It is proved that TDLAS technology has many advantages, including fast response, high sensitivity and resolution. This research provides a technique for monitoring secular change of CO2 in atmosphere.

Characterization of thin film CO2 ice through the infrared ν1 + ν3 combination mode

NASA Astrophysics Data System (ADS)

He, Jiao; Vidali, Gianfranco

2018-01-01

Carbon dioxide is abundant in ice mantles of dust grains; some is found in the pure crystalline form as inferred from the double peak splitting of the bending profile at about 650 cm-1. To study how CO2 segregates into the pure form from water-rich mixtures of ice mantles and how it then crystallizes, we used Reflection Absorption InfraRed Spectroscopy to study the structural change of pure CO2 ice as a function of both ice thickness and temperature. We found that the ν1 + ν3 combination mode absorption profile at 3708 cm-1 provides an excellent probe to quantify the degree of crystallinity in CO2 ice. We also found that between 20 and 30 K, there is an ordering transition that we attribute to reorientation of CO2 molecules, while the diffusion of CO2 becomes significant at much higher temperatures. In the formation of pure crystalline CO2 in interstellar medium ices, the rate limiting process is the diffusion/segregation of CO2 molecules in the ice instead of the phase transition from amorphous to crystalline after clusters/islands of CO2 are formed.

[Photometric determination of cobalt by the formation of a multi-ligand complex of Co(II)-C16H16N2S2O2-DEA].

PubMed

Xue, Zhao-ming; Xie, An-jian; Huang, Fang-zhi; Ma, Wen

2002-08-01

The new ligand vanillin S-benzyldithocarbazte(HL) and its complex Co(II)-C16H16N2S2O2-DEA was synthesized and characterized by IR, UV-Vis. The optimum color conditions of the complex in 95% ethanol solution(including reaction temperature T, heating time t, and the concentrations of the three components) have been studied by quadratic regression orthogonal design method. According to the quadratic-regression equation, the maximum absorption intensity and optimum color conditions of the complex were calculated. The results were consistent with those gotten by experiment. The influences of common ions on the determination of cobalt and the methods to eliminate the influence are investigated. The maximum absorption peak of the complex is found at 404 nm and molar absorptivity is 5.29 x 10(4) L.mol-1.cm-1. Beer's law is obeyed in the range of 0-20 micrograms.(25 mL)-1 for Co(II). The composition of Co2+ to HL, and DEA in the complex is 1:2:1. The new method was successfully utilized to the determination of cobalt in VB12 and medicine.

Proposal to Simultaneously Profile Wind and CO2 on Earth and Mars With 2-micron Pulsed Lidar Technologies

NASA Technical Reports Server (NTRS)

Singh, Upendra N.; Koch, Grady J.; Kavaya, Michael J.; Amzajerdian, Farzin; Ismail, Syed; Emmitt, David

2005-01-01

2-micron lidar technology has been in use and under continued improvement for many years toward wind measurements. But the 2-micron wavelength region is also rich in absorption lines of CO2 (and H2O to a lesser extent) that can be exploited with the differential absorption lidar (DIAL) technique to make species concentration measurements. A coherent detection receiver offers the possibility of making combined wind and DIAL measurements with wind derived from frequency shift of the backscatter spectrum and species concentration derived from power of the backscatter spectrum. A combined wind and CO2 measurement capability is of interest for applications on both Earth and Mars. CO2 measurements in the Earth atmosphere are of importance to studies of the global carbon cycle. Data on vertically-resolved CO2 profiles over large geographical observations areas are of particular interest that could potentially be made by deploying a lidar on an aircraft or satellite. By combining CO2 concentration with wind measurements an even more useful data product could be obtained in the calculation of CO2 flux. A challenge to lidar in this application is that CO2 concentration measurements must be made with a high level of precision and accuracy to better than 1%. The Martian atmosphere also presents wind and CO2 measurement problems that could be met with a combined DIAL/Doppler lidar. CO2 concentration in this scenario would be used to calculate atmospheric density since the Martian atmosphere is composed of 95% CO2. The lack of measurements of Mars atmospheric density in the 30-60 km range, dust storm formation and movements, and horizontal wind patterns in the 0-20 km range pose significant risks to aerocapture, and entry, descent, and landing of future robotic and human Mars missions. Systematic measurement of the Mars atmospheric density and winds will be required over several Mars years, supplemented with day-of-entry operational measurements. To date, there have been 5 successful robotic landings on Mars. Atmospheric density and wind reconstruction has been performed for 3 of these entries (the two Viking landers and Mars Pathfinder). At present, all Mars atmospheric density and wind models have these 3 entries (at widely scattered positions and seasons) as their basis, supplemented by coarse orbital measurements of atmospheric opacity and temperature. This lack of data leads to a large uncertainty in prediction of the Mars atmospheric density and winds in the altitude regime where deceleration of landers will occur. This uncertainty will have a dramatically large impact on mass, cost and risk. The precision and accuracy for application to Mars is not as stringent as Earth, but Mars does pose a challenge in needing a high level of wavelength stability and control in order to reference wavelength to the narrow linewidths found in the low atmospheric pressure of Mars, as illustrated in Figure 1.

Carbon monoxide improves neuronal differentiation and yield by increasing the functioning and number of mitochondria.

PubMed

Almeida, Ana S; Sonnewald, Ursula; Alves, Paula M; Vieira, Helena L A

2016-08-01

The process of cell differentiation goes hand-in-hand with metabolic adaptations, which are needed to provide energy and new metabolites. Carbon monoxide (CO) is an endogenous cytoprotective molecule able to inhibit cell death and improve mitochondrial metabolism. Neuronal differentiation processes were studied using the NT2 cell line, which is derived from human testicular embryonic teratocarcinoma and differentiates into post-mitotic neurons upon retinoic acid treatment. CO-releasing molecule A1 (CORM-A1) was used do deliver CO into cell culture. CO treatment improved NT2 neuronal differentiation and yield, since there were more neurons and the total cell number increased following the differentiation process. CO supplementation enhanced the mitochondrial population in post-mitotic neurons derived from NT2 cells, as indicated by an increase in mitochondrial DNA. CO treatment during neuronal differentiation increased the extent of the classical metabolic change that occurs during neuronal differentiation, from glycolytic to more oxidative metabolism, by decreasing the ratio of lactate production and glucose consumption. The expression of pyruvate and lactate dehydrogenases was higher, indicating an augmented oxidative metabolism. Moreover, these findings were corroborated by an increased percentage of (13) C incorporation from [U-(13) C]glucose into the tricarboxylic acid cycle metabolites malate and citrate, and also glutamate and aspartate in CO-treated cells. Finally, under low levels of oxygen (5%), which enhances glycolytic metabolism, some of the enhancing effects of CO on mitochondria were not observed. In conclusion, our data show that CO improves neuronal and mitochondrial yield by stimulation of tricarboxylic acid cycle activity, and thus oxidative metabolism of NT2 cells during the process of neuronal differentiation. The process of cell differentiation is coupled with metabolic adaptations. Carbon monoxide (CO) is an endogenous cytoprotective gasotransmitter able to prevent cell death and improve mitochondrial metabolism. Herein CO supplementation improved neuronal differentiation yield, by enhancing mitochondrial population and promoting the classical metabolic change that occurs during neuronal differentiation, from glycolytic to oxidative metabolism. © 2016 International Society for Neurochemistry.

The molecular physics of photolytic fractionation of sulfur and oxygen isotopes in planetary atmospheres (Invited)

NASA Astrophysics Data System (ADS)

Johnson, M. S.; Schmidt, J. A.; Hattori, S.; Danielache, S.; Meusinger, C.; Schinke, R.; Ueno, Y.; Nanbu, S.; Kjaergaard, H. G.; Yoshida, N.

2013-12-01

Atmospheric photochemistry is able to produce large mass independent anomalies in atmospheric trace gases that can be found in geological and cryospheric records. This talk will present theoretical and experimental investigations of the molecular mechanisms producing photolytic fractionation of isotopes with special attention to sulfur and oxygen. The zero point vibrational energy (ZPE) shift and reflection principle theories are starting points for estimating isotopic fractionation, but these models ignore effects arising from isotope-dependent changes in couplings between surfaces, excited state dynamics, line densities and hot band populations. The isotope-dependent absorption spectra of the isotopologues of HCl, N2O, OCS, CO2 and SO2 have been examined in a series of papers and these results are compared with experiment and ZPE/reflection principle models. Isotopic fractionation in planetary atmospheres has many interesting applications. The UV absorption of CO2 is the basis of photochemistry in the CO2-rich atmospheres of the ancient Earth, and of Mars and Venus. For the first time we present accurate temperature and isotope dependent CO2 absorption cross sections with important implications for photolysis rates of SO2 and H2O, and the production of a mass independent anomaly in the Ox reservoir. Experimental and theoretical results for OCS have implications for the modern stratospheric sulfur budget. The absorption bands of SO2 are complex with rich structure producing isotopic fractionation in photolysis and photoexcitation.

Observation of high-spin mixed oxidation state of cobalt in ceramic Co3TeO6

NASA Astrophysics Data System (ADS)

Singh, Harishchandra; Ghosh, Haranath; Chandrasekhar Rao, T. V.; Sinha, A. K.; Rajput, Parasmani

2014-12-01

We report coexistence of high spin Co3+ and Co2+ in ceramic Co3TeO6 using X-ray Absorption Near Edge Structure (XANES), DC magnetization, and first principles ab-initio calculations. The main absorption line of cobalt Co K-edge XANES spectra, along with a linear combination fit, led us to estimate relative concentration of Co2+ and Co3+as 60:40. The pre edge feature of XANES spectrum shows crystal field splitting of ˜1.26 eV between eg and t2g states, suggesting a mixture of high spin states of both Co2+ and Co3+. Temperature dependent high field DC magnetization measurements reveal dominant antiferromagnetic order with two Neel temperatures (TN1 ˜ 29 K and TN2 ˜ 18 K), consistent with single crystal study. A larger effective magnetic moment is observed in comparison to that reported for single crystal (which contains only Co2+), supports our inference that Co3+ exists in high spin state. Furthermore, we show that both Co2+ and Co3+ being in high spin states constitute a favorable ground state through first principles ab-initio calculations, where Rietveld refined synchrotron X-ray diffraction data are used as input.

Thiazide-sensitive Na+ -Cl- cotransporter (NCC) gene inactivation results in increased duodenal Ca2+ absorption, enhanced osteoblast differentiation and elevated bone mineral density.

PubMed

Hsu, Yu-Juei; Yang, Sung-Sen; Cheng, Chih-Jen; Liu, Shu-Ting; Huang, Shih-Ming; Chau, Tom; Chu, Pauling; Salter, Donald M; Lee, Herng-Sheng; Lin, Shih-Hua

2015-01-01

Inactivation of the thiazide-sensitive sodium chloride cotransporter (NCC) due to genetic mutations in Gitelman's syndrome (GS) or pharmacological inhibition with thiazide diuretics causes hypocalciuria and increased bone mineral density (BMD) with unclear extrarenal calcium (Ca(2+) ) regulation. We investigated intestinal Ca(2+) absorption and bone Ca(2+) metabolism in nonsense Ncc Ser707X (S707X) homozygous knockin mice (Ncc(S707X/S707X) mice). Compared to wild-type and heterozygous knockin littermates, Ncc(S707X/S707X) mice had increased intestinal absorption of (45) Ca(2+) and expression of the active Ca(2+) transport machinery (transient receptor potential vanilloid 6, calbindin-D9K , and plasma membrane Ca(2+) ATPase isoform 1b). Ncc(S707X/S707X) mice had also significantly increased Ca(2+) content accompanied by greater mineral apposition rate (MAR) in their femurs and higher trabecular bone volume, cortical bone thickness, and BMD determined by μCT. Their osteoblast differentiation markers, such as bone alkaline phosphatase, procollagen I, osteocalcin, and osterix, were also significantly increased while osteoclast activity was unaffected. Analysis of marrow-derived bone cells, either treated with thiazide or directly cultured from Ncc S707X knockin mice, showed that the differentiation of osteoblasts was associated with increased phosphorylation of mechanical stress-induced focal adhesion kinase (FAK) and extracellular signal-regulated kinase (ERK). In conclusion, NCC inhibition stimulates duodenal Ca(2+) absorption as well as osteoblast differentiation and bone Ca(2+) storage, possibly through a FAK/ERK dependent mechanism. © 2014 American Society for Bone and Mineral Research.

Intra- and inter-atomic optical transitions of Fe, Co, and Ni ferrocyanides studied using first-principles many-electron calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watanabe, Shinta, E-mail: s-watanabe@nucl.nagoya-u.ac.jp, E-mail: j-onoe@nucl.nagoya-u.ac.jp; Sawada, Yuki; Nakaya, Masato

We have investigated the electronic structures and optical properties of Fe, Co, and Ni ferrocyanide nanoparticles using first-principles relativistic many-electron calculations. The overall features of the theoretical absorption spectra for Fe, Ni, and Co ferrocyanides calculated using a first-principles many-electron method well reproduced the experimental one. The origins of the experimental absorption spectra were clarified by performing a configuration analysis based on the many-electron wave functions. For Fe ferrocyanide, the experimental absorption peaks originated from not only the charge-transfer transitions from Fe{sup 2+} to Fe{sup 3+} but also the 3d-3d intra-transitions of Fe{sup 3+} ions. In addition, the spin crossovermore » transition of Fe{sup 3+} predicted by the many-electron calculations was about 0.24 eV. For Co ferrocyanide, the experimental absorption peaks were mainly attributed to the 3d-3d intra-transitions of Fe{sup 2+} ions. In contrast to the Fe and Co ferrocyanides, Ni ferrocyanide showed that the absorption peaks originated from the 3d-3d intra-transitions of Ni{sup 3+} ions in a low-energy region, while from both the 3d-3d intra-transitions of Fe{sup 2+} ions and the charge-transfer transitions from Fe{sup 2+} to Ni{sup 3+} in a high-energy region. These results were quite different from those of density-functional theory (DFT) calculations. The discrepancy between the results of DFT calculations and those of many-electron calculations suggested that the intra- and inter-atomic transitions of transition metal ions are significantly affected by the many-body effects of strongly correlated 3d electrons.« less

Carbon dioxide on the satellites of Saturn: Results from the Cassini VIMS investigation and revisions to the VIMS wavelength scale

USGS Publications Warehouse

Cruikshank, D.P.; Meyer, A.W.; Brown, R.H.; Clark, R.N.; Jaumann, R.; Stephan, K.; Hibbitts, C.A.; Sandford, S.A.; Mastrapa, R.M.E.; Filacchione, G.; Ore, C.M.D.; Nicholson, P.D.; Buratti, B.J.; McCord, T.B.; Nelson, R.M.; Dalton, J.B.; Baines, K.H.; Matson, D.L.

2010-01-01

Several of the icy satellites of Saturn show the spectroscopic signature of the asymmetric stretching mode of C-O in carbon dioxide (CO2) at or near the nominal solid-phase laboratory wavelength of 4.2675 ??m (2343.3 cm-1), discovered with the Visible-Infrared Mapping Spectrometer (VIMS) on the Cassini spacecraft. We report here on an analysis of the variation in wavelength and width of the CO2 absorption band in the spectra of Phoebe, Iapetus, Hyperion, and Dione. Comparisons are made to laboratory spectra of pure CO2, CO2 clathrates, ternary mixtures of CO2 with other volatiles, implanted and adsorbed CO2 in non-volatile materials, and ab initio theoretical calculations of CO2 * nH2O. At the wavelength resolution of VIMS, the CO2 on Phoebe is indistinguishable from pure CO2 ice (each molecule's nearby neighbors are also CO2) or type II clathrate of CO2 in H2O. In contrast, the CO2 band on Iapetus, Hyperion, and Dione is shifted to shorter wavelengths (typically ???4.255 ??m (???2350.2 cm-1)) and broadened. These wavelengths are characteristic of complexes of CO2 with different near-neighbor molecules that are encountered in other volatile mixtures such as with H2O and CH3OH, and non-volatile host materials like silicates, some clays, and zeolites. We suggest that Phoebe's CO2 is native to the body as part of the initial inventory of condensates and now exposed on the surface, while CO2 on the other three satellites results at least in part from particle or UV irradiation of native H2O plus a source of C, implantation or accretion from external sources, or redistribution of native CO2 from the interior. The analysis presented here depends on an accurate VIMS wavelength scale. In preparation for this work, the baseline wavelength calibration for the Cassini VIMS was found to be distorted around 4.3 ??m, apparently as a consequence of telluric CO2 gas absorption in the pre-launch calibration. The effect can be reproduced by convolving a sequence of model detector response profiles with a deep atmospheric CO2 absorption profile, producing distorted detector profile shapes and shifted central positions. In a laboratory blackbody spectrum used for radiance calibration, close examination of the CO2 absorption profile shows a similar deviation from that expected from a model. These modeled effects appear to be sufficient to explain the distortion in the existing wavelength calibration now in use. A modification to the wavelength calibration for 13 adjacent bands is provided. The affected channels span about 0.2 ??m centered on 4.28 ??m. The maximum wavelength change is about 10 nm toward longer wavelength. This adjustment has implications for interpretation of some of the spectral features observed in the affected wavelength interval, such as from CO2, as discussed in this paper.

Optical graphene quantum dots gas sensors: Theoretical study

NASA Astrophysics Data System (ADS)

Raeyani, D.; Shojaei, S.; Ahmadi-Kandjani, S.

2018-02-01

In this work, we theoretically studied the changes of graphene quantum dots (GQD) absorption spectra under the influence of different gases to indicate optical gas sensing features of GQDs. The adsorption of gas molecules such as CO2, N2 and Ar on GQDs have been theoretically investigated through time-dependent density functional theory (TDDFT) calculations. Our study revealed that UV-Vis absorption spectrum of GQDs in the presence of CO2 undergoes considerable changes than that of N2 and Ar. The shift of maximum absorption wavelength for adsorption of CO2, N2 and Ar in same distance from GQD in addition to density of state (DOS) and orbital analyses have been obtained. To verify our theoretical results, comparison with experimental study has been done and good agreement has been observed. Comparing with electrical property of GQD, optical properties showed an efficient tool to be implemented in gas adsorption and paves the way towards GQD optical gas sensors.

Multispecies absorption spectroscopy of detonation events at 100  kHz using a fiber-coupled, time-division-multiplexed quantum-cascade-laser system.

PubMed

Rein, Keith D; Roy, Sukesh; Sanders, Scott T; Caswell, Andrew W; Schauer, Frederick R; Gord, James R

2016-08-10

A mid-infrared fiber-coupled laser system constructed around three time-division-multiplexed quantum-cascade lasers capable of measuring the absorption spectra of CO, CO₂, and N₂O at 100 kHz over a wide range of operating pressures and temperatures is demonstrated. This system is first demonstrated in a laboratory burner and then used to measure temperature, pressure, and concentrations of CO, CO₂, and N₂O as a function of time in a detonated mixture of N₂O and C₃H₈. Both fuel-rich and fuel-lean detonation cases are outlined. High-temperature fluctuations during the blowdown are observed. Concentrations of CO are shown to decrease with time for fuel-lean conditions and increase for fuel-rich conditions.

Optimization of silicon waveguides for gas detection application at mid-IR wavelengths

NASA Astrophysics Data System (ADS)

Butt, M. A.; Kozlova, E. S.

2018-04-01

There are several trace gases such as N2O, CO, CO2, NO, H2O, NO2, NH3, CH4 etc. which have their absorption peaks in Mid-IR spectrum These gases strongly absorb in the mid-IR > 2.5 μm spectral region due to their fundamental rotational and vibrational transitions. In this work, we modelled and optimized three different kinds of waveguides such as rib, strip and slot based on silicon platform to obtain maximum evanescent field ratio. These waveguides are designed at 3.39 μm and 4.67 μm which correspond to the absorption line of methane (CH4) and carbon monoxide (CO) respectively.

Differential behavioral sensitivity to carbon dioxide (CO2) inhalation in rats

PubMed Central

Winter, Andrew; Ahlbrand, Rebecca; Naik, Devanshi; Sah, Renu

2017-01-01

Inhalation of carbon dioxide (CO2) is frequently employed as a biological challenge to evoke intense fear and anxiety. In individuals with panic disorder, CO2 reliably evokes panic attacks. Sensitivity to CO2 is highly heterogeneous among individuals, and although a genetic component is implicated, underlying mechanisms are not clear. Preclinical models that can simulate differential responsivity to CO2 are therefore relevant. In the current study we investigated CO2-evoked behavioral responses in four different rat strains: Sprague-Dawley (SD), Wistar (W), Long Evans (LE) and Wistar-Kyoto, (WK) rats. We also assessed tryptophan hydroxylase 2 (TPH-2)-positive serotonergic neurons in anxiety/panic regulatory subdivisions of the dorsal raphe nucleus (DR), as well as dopamine β hydroxylase (DβH)-positive noradrenergic neurons in the locus coeruleus, implicated in central CO2-chemosensitivity. Behavioral responsivity to CO2 inhalation varied between strains. CO2-evoked immobility was significantly higher in LE and WK rats as compared with W and SD cohorts. Differences were also observed in CO2-evoked rearing and grooming behaviors. Exposure to CO2 did not produce conditioned behavioral responses upon re-exposure to CO2 context in any strain. Reduced TPH-2 positive cell counts were observed specifically in the panic-regulatory dorsal raphe ventrolateral (DRVL)-ventrolateral periaqueductal grey (VLPAG) subdivision in CO2-sensitive strains. Conversely, DβH positive cell counts within the LC were significantly higher in CO2-sensitive strains. Collectively, our data provide evidence for strain dependent, differential CO2-sensitivity and potential differences in monoaminergic systems regulating panic and anxiety. Comparative studies between CO2-vulnerable and resistant strains may facilitate the mechanistic understanding of differential CO2-sensitivity in the development of panic and anxiety disorders. PMID:28087339

First Spectroscopic Identification of Massive Young Stellar Objects in the Galactic Center

NASA Technical Reports Server (NTRS)

An, Deokkeun; Ramirez, V.; Sellgren, Kris; Arendt, Richard G.; Boogert, A. C.; Schultheis, Mathias; Stolovy, Susan R.; Cotera, Angela S.; Robitaille, Thomas P.; Smith, Howard A.

2009-01-01

We report the detection of several molecular gas-phase and ice absorption features in three photometrically-selected young stellar object (YSO) candidates in the central 280 pc of the Milky Way. Our spectra, obtained with the Infrared Spectrograph (IRS) onboard the Spitzer Space Telescope, reveal gas-phase absorption from CO2 (15.0 microns), C2H2 (13.7 microns) and HCN (14.0 microns). We attribute this absorption to warm, dense gas in massive YSOs. We also detect strong and broad 15 microns CO2 ice absorption features, with a remarkable double-peaked structure. The prominent long-wavelength peak is due to CH3OH-rich ice grains, and is similar to those found in other known massive YSOs. Our IRS observa.tions demonstra.te the youth of these objects, and provide the first spectroscopic identification of massive YSOs in the Galactic Center.

40 CFR 60.54 - Test methods and procedures.

Code of Federal Regulations, 2010 CFR

2010-07-01

... at each point for equal increments of time. (2) Excess air measurements may be used to determine the... Section 60.54 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS... “adjusted” CO2 concentration [(%CO2)adj], which accounts for the effects of CO2 absorption and dilution air...

2 inch size Czochralski growth and scintillation properties of Li+ co-doped Ce:Gd3Ga3Al2O12

NASA Astrophysics Data System (ADS)

Kamada, Kei; Shoji, Yasuhiro; Kochurikhin, Vladimir V.; Yoshino, Masao; Okumura, Satoshi; Yamamoto, Seiichi; Yeom, Jung Yeol; Kurosawa, Shunsuke; Yokota, Yuui; Ohashi, Yuji; Nikl, Martin; Yoshino, Masao; Yoshikawa, Akira

2017-03-01

The 2 inch size Li 0.15 and 1.35 mol% co-doped Ce:Gd3Al2Ga3O12 single crystals were prepared by the Czochralski (Cz) method. Absorption and luminescence spectra were measured together with several other scintillation characteristics, namely the scintillation decay and light yield to reveal the effect of Li co-doping. Ce4+ CT absorption below 350 nm is clearly enhanced by Li co-doping as same as divalent ions co-doping. By 1.35 at.% Li co-doping, light yield was decrease to 88% of the Ce: GAGG standard and decay time was accelerated to 34.3ns 21.0%, 84.6ns 68.7%, 480ns 10.3%. The timing resolution measurement for a pair of 3 × 3 × 3mm3 size Li,Ce:GAGG scintillator crystals was performed using Si-PMs and the timing resolution of the 1.35 at.% Li co-doped Ce:GAGG was 218ps.

Growth and optical properties of Co,Nd:LaMgAl11O19

NASA Astrophysics Data System (ADS)

Xu, Peng; Xia, Changtai; Di, Juqing; Xu, Xiaodong; Sai, Qinglin; Wang, Lulu

2012-12-01

Nd,Co:LaMgAl11O19 (abbreviated as Co,Nd:LMA) was grown using the Czochralski method. The structure, polarized absorption spectrum, fluorescence spectrum, and fluorescence decay time were analyzed. The as-grown crystal had very wide absorption bands at 794 nm, which can be pumped by GaAs laser diode without temperature stabilization. Two strong emission bands were present at 1056 nm and 1082 nm with full-width at half-maximum (FWHM) of 6 and 8 nm, respectively. The large FWHM is due to the inhomogeneity of the Nd ion sites. The lifetimes of the 4F3/2 manifold of Co,Nd:LMA at room temperature monitored at 905 nm, 1056 nm, and 1344 nm were 292, 288, and 350 μs, respectively, which was caused by the different contribution of the three different sites with D3h and C2v symmetry. The absorption band of Co is from 1.3 μm to 1.6 μm, and Co,Nd:LMA still has a strong emission around the 1.38 μm, indicating that the Co,Nd:LMA can be applied as a potential self-Q-switched material operating at 1.3 μm.

Process and Material Design for Micro-Encapsulated Ionic Liquids in Post-Combustion CO 2 Capture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hong, Bo; Brennecke, Joan F; McCready, Mark

Aprotic Heterocyclic Anion (AHA) Ionic Liquids (ILs) have been identified as promising new solvents for post-combustion carbon capture due to their high CO 2 uptake and the high tenability 1,2 of their binding energy with CO 2. Some of these compounds change phase (solid to liquid) on absorption of CO 2; these Phase Change ILs (PCILs)3 offer the additional advantage that part of the heat needed to desorb the CO2 from the absorbent is provided by the heat of fusion as the PCIL solidifies upon release of CO 2. However, the relatively high viscosity of AHA ILs and the occurrencemore » of a phase change in PCILs present challenges for conventional absorption equipment. To overcome these challenges we are pursuing the use of new technology to micro-encapsulate the AHA ILs and PCILs. Our partners at Lawrence Livermore National Laboratory have successfully demonstrated this technology in the application of post-combustion carbon capture with sodium and potassium carbonate solutions,4 and have recently shown the feasibility of micro-encapsulation of an AHA IL for carbon capture.5 The large effective surface area and high CO 2 permeability of the micro-capsules is expected to offset the drawback of the high IL viscosity and to provide for a more efficient and cost-effective mass transfer operation involving AHA ILs and PCILs. These opportunities, however, present us with both process and materials design questions. For example, what is the target CO 2 absorption strength (enthalpy of chemical absorption) for the tunable AHA IL? What is the target for micro-capsule diameter in order to obtain a high mass transfer rate and good fluidization performance? What are the appropriate temperatures and pressures for the absorber and stripper? In order to address these and other questions, we have developed a rate-based model of a post-combustion CO 2 capture process using micro-encapsulated ILs. As a performance baseline, we have also developed a rate-based model of a standard packed bed absorber using an un-encapsulated AHA IL absorbent. Using such models we can determine optimal CO 2 capture performance and investigate the sensitivity of the optimum with respect to the key thermo-physical and transport properties of the IL (e.g., CO 2 binding energy, viscosity, etc.) and the micro-capsules (e.g. diameter, CO 2 permeability, etc.). Results of these process and material design studies will be presented, and the performance of this novel micro-encapsulation technology will be assessed.« less

Airborne Laser Infrared Absorption Spectrometer (ALIAS-II) for in situ Atmospheric Measurements of N(sub 2)0, CH(sub 4), CO, HCl, and NO(sub 2) from Balloon or RPA Platforms

NASA Technical Reports Server (NTRS)

Scott, D.; Herman, R.; Webster, C.; May, R.; Flesch, G.; Moyer, E.

1998-01-01

The Airborne Laser Infrared Absorption Spectrometer II (ALIAS-II) is a lightweight, high-resolution (0.0003 cm-1), scanning, mid-infrared absorption spectrometer based on cooled (80 K) lead-salt tunable diode laser sources.

Preparation of nitrogen and sulfur co-doped ordered mesoporous carbon for enhanced microwave absorption performance

NASA Astrophysics Data System (ADS)

Yuan, Xiaoyan; Xue, Xingkun; Ma, Hailong; Guo, Shouwu; Cheng, Laifei

2017-09-01

Ordered mesoporous carbon nanomaterials (OMCs) co-doped with homogeneous nitrogen and sulfur heteroatoms were prepared by nanocasting with the pyrrole oligomer catalyzed by sulfuric acid as a precursor and ordered mesoporous silica SBA-15 as a hard-template. By multi-technique approach utilization, it was demonstrated that the N and S co-doped OMCs possessed high ordered mesoporous structures, large surface areas and homogeneous distribution of heteroatoms. As a microwave absorber, the as-prepared materials exhibited a minimum reflection loss (RL) of -32.5 dB at the thickness of 2.5 mm and an absorption bandwidth of 3.2 GHz (RL < -10 dB) in X-band (8.2-12.4 GHz). The good microwave absorption performance was mainly originated from the high electrical conductivity induced by the high surface activity and special structures. And microwave energy can be effectively attenuated through multiple reflections and absorptions in complex conductive network. The design strategy in this work would contribute to the production of a lightweight absorber, presenting a strong absorbency and a wide bandwidth in microwave frequency.

Tomographic multiaxis-differential optical absorption spectroscopy observations of Sun-illuminated targets: a technique providing well-defined absorption paths in the boundary layer

NASA Astrophysics Data System (ADS)

Frins, Erna; Bobrowski, Nicole; Platt, Ulrich; Wagner, Thomas

2006-08-01

A novel experimental procedure to measure the near-surface distribution of atmospheric trace gases by using passive multiaxis differential absorption optical spectroscopy (MAX-DOAS) is proposed. The procedure consists of pointing the receiving telescope of the spectrometer to nonreflecting surfaces or to bright targets placed at known distances from the measuring device, which are illuminated by sunlight. We show that the partial trace gas absorptions between the top of the atmosphere and the target can be easily removed from the measured total absorption. Thus it is possible to derive the average concentration of trace gases such as NO2, HCHO, SO2, H2O, Glyoxal, BrO, and others along the line of sight between the instrument and the target similar to the well-known long-path DOAS observations (but with much less expense). If tomographic arrangements are used, even two- or three-dimensional trace gas distributions can be retrieved. The basic assumptions of the proposed method are confirmed by test measurements taken across the city of Heidelberg.

Study of cobalt effect on structural and optical properties of Dy doped ZnO nanoparticles

NASA Astrophysics Data System (ADS)

Kumar, Pawan; Pandey, Praveen C.

2018-05-01

The present study has been carried out to investigate the effect of Co doping on structural and optical properties of Dy doped ZnO nanoparticles. We have prepared pure Zinc oxide, Dy (1%) doped ZnO and Dy (1%) doped ZnO co-doped with Co(2%) with the help of simple sol-gel combustion method. The structural analysis carried out using X-ray diffraction spectra (XRD) indicates substitution of Dy and Co at Zn site of ZnO crystal structure and hexagonal crystal structure without any secondary phase formation in all the samples. The surface morphology was analyzed by transmission electron microscopy (TEM). Absorption study indicates that Dy doping causes a small shift in band edge, while Co co-doping results significant change is absorption edge as well as introduce defect level absorption in the visible region. The band gap of samples decreases due to Dy and Co doping, which can be attributed to defect level formation below the conduction band in the system.

Treatment of tooth fracture by medium-energy CO2 laser and DP-bioactive glass paste: the interaction of enamel and DP-bioactive glass paste during irradiation by CO2 laser.

PubMed

Lin, C P; Tseng, Y C; Lin, F H; Liao, J D; Lan, W H

2001-03-01

Acute trauma or trauma associated with occlusal disturbance can produce tooth crack or fracture. Although several methods are proposed to treat the defect, however, the prognosis is generally poor. If the fusion of a tooth fracture by laser is possible, it will offer an alternative to extraction or at least serve as an adjunctive treatment in the reconstruction. We have tried to use a continuous-wave CO2 laser and a newly developed DP-bioactive glass paste (DPGP) to fuse or bridge tooth crack or fracture lines. Both the DP-bioactive glass paste and tooth enamel have strong absorption bands at the wavelength of 10.6 microm. Therefore, under CO2 laser, DPGP and enamel should have an effective absorption and melt together. The interface between DPGP and enamel could be regarded as a mixture of DPGP and enamel (DPG-E). The study focused on the phase transformation, microstructure, functional group and thermal behavior of DPG-E with or without CO2 laser irradiation, by the analytical techniques of XRD, FTIR, DTA/TGA, and SEM. The results of XRD showed that the main crystal phase in the DPG-E was dicalcium phosphate dihydrate (CaHPO4.2H2O). It changed into CaHPO4, gamma-Ca2P2O7, beta-Ca2P2O7 and finally alpha-Ca2P2O7 with increasing temperature. In the FTIR analysis, the 720 cm(-1) absorption band ascribed to the P-O-P linkage in pyrophosphate rose up and the intensities of the OH- bands reduced after laser irradiation. In regard to the results of DTA/TGA after irradiation, the weight loss decreased due to the removal of part of absorption water and crystallization water by the CO2 laser. SEM micrographs revealed that the melted masses and the plate-like crystals formed a tight chemical bond between the enamel and DPGP. We expect that DPGP with the help of CO2 laser can be an alternative to the treatment of tooth crack or fracture.

Nonlinear Absorption and Heating of Dense Plasmas.

DTIC Science & Technology

plasma focus both illuminated by a high intensity CO2 laser. Results indicate the previously noted increases in absorption due to the inclusion of the nonlinear saturation mechanism. The previously obtained increases in absorption with increasing density scale height and decreasing temperatures are also recovered. The

Qualification of a Multi-Channel Infrared Laser Absorption Spectrometer for Monitoring CO, HCl, HCN, HF, and CO2 Aboard Manned Spacecraft

NASA Technical Reports Server (NTRS)

Briggs, Ryan M.; Frez, Clifford; Forouhar, Siamak; May, Randy D.; Meyer, Marit E.; Kulis, Michael J.; Berger, Gordon M.

2015-01-01

Monitoring of specific combustion products can provide early-warning detection of accidental fires aboard manned spacecraft and also identify the source and severity of combustion events. Furthermore, quantitative in situ measurements are important for gauging levels of exposure to hazardous gases, particularly on long-duration missions where analysis of returned samples becomes impractical. Absorption spectroscopy using tunable laser sources in the 2 to 5 micrometer wavelength range enables accurate, unambiguous detection of CO, HCl, HCN, HF, and CO2, which are produced in varying amounts through the heating of electrical components and packaging materials commonly used aboard spacecraft. Here, we report on calibration and testing of a five-channel laser absorption spectrometer designed to accurately monitor ambient gas-phase concentrations of these five compounds, with low-level detection limits based on the Spacecraft Maximum Allowable Concentrations. The instrument employs a two-pass absorption cell with a total optical pathlength of 50 cm and a dedicated infrared semiconductor laser source for each target gas. We present results from testing the five-channel sensor in the presence of trace concentrations of the target compounds that were introduced using both gas sources and oxidative pyrolysis (non-flaming combustion) of solid material mixtures.

Carbon dioxide capture via aqueous N-methyldiethanolamine (MDEA)-1-butyl-3-methylimidazolium acetate ([bmim][Ac]) hybrid solvent

NASA Astrophysics Data System (ADS)

Hailegiorgis, Sintayehu Mekuria; Khan, Saleem Nawaz; Abdolah, Nur Hanis H.; Ayoub, Muhammad; Tesfamichael, Aklilu

2017-10-01

In this study, aqueous hybrid solvents from a mixture of aqueous N-methyldiethanolamine (MDEA) and 1-butyl-3-methylimidazolium acetate, [bmim][Ac] as ionic liquids (ILs) were formulated at different mass ratio. In each aqueous hybrid solvents, the concentrations of MDEA were kept constant at 30 wt%. In the hybrid solvents, the solubility of CO2 was investigated at [bmim][Ac] concentration of 10 wt% and 20 wt%, respectively and results were compared with pure aqueous MDEA solvent. It was observed that the solubility of CO2 is significantly improved in the hybrid solvent as compared to the solubility of CO2 in pure aqueous MDEA solvent. However, increasing the concentration of [bmim][Ac] from 10 wt% to 20 wt% has a negative effect on the solubility of CO2 due to viscosity effect. It was also observed that hybrid solvents with 10 wt% [bmim][Ac] has better CO2 loading capacity. Increasing pressure from 10 bar to 20 bar has demonstrated an increase in CO2 absorption capacity as well as CO2 absorption rate. Hybrid solvents prepared from amine and imidazolium ILs will be a promising solvent in the capturing of CO2.

Line mixing in a N2-broadened CO2 Q branch observed with a tunable diode laser

NASA Technical Reports Server (NTRS)

Gentry, Bruce; Strow, L. Larrabee

1987-01-01

Line-mixing effects have been observed in the infrared Q branch of the (11/1/0,03/1/0)I-00/0/0 band of CO2 at 2076/cm. A tunable diode laser spectrometer was used to record spectra of CO2 broadened by N2 and O2 at total pressures ranging from 100 to 720 torr. The observed absorption coefficients are up to 65 percent lower than those calculated using an isolated Lorentzian line approximation. A simple energy gap scaling law is used to determine the off-diagonal relaxation matrix elements from the known pressure-broadening coefficients. The spectra calculated using these matrix elements reproduces the observed absorption coefficients to within several percent.

Plasmonic nanopatch array with integrated metal–organic framework for enhanced infrared absorption gas sensing

DOE PAGES

Chong, Xinyuan; Kim, Ki-joong; Zhang, Yujing; ...

2017-06-06

In this letter, we present a nanophotonic device consisting of plasmonic nanopatch array (NPA) with integrated metal–organic framework (MOF) for enhanced infrared absorption gas sensing. By designing a gold NPA on a sapphire substrate, we are able to achieve enhanced optical field that spatially overlaps with the MOF layer, which can adsorb carbon dioxide (CO 2) with high capacity. Additionally, experimental results show that this hybrid plasmonic–MOF device can effectively increase the infrared absorption path of on-chip gas sensors by more than 1100-fold. Lastly, the demonstration of infrared absorption spectroscopy of CO 2 using the hybrid plasmonic–MOF device proves amore » promising strategy for future on-chip gas sensing with ultra-compact size.« less

Plasmonic nanopatch array with integrated metal–organic framework for enhanced infrared absorption gas sensing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chong, Xinyuan; Kim, Ki-joong; Zhang, Yujing

In this letter, we present a nanophotonic device consisting of plasmonic nanopatch array (NPA) with integrated metal–organic framework (MOF) for enhanced infrared absorption gas sensing. By designing a gold NPA on a sapphire substrate, we are able to achieve enhanced optical field that spatially overlaps with the MOF layer, which can adsorb carbon dioxide (CO 2) with high capacity. Additionally, experimental results show that this hybrid plasmonic–MOF device can effectively increase the infrared absorption path of on-chip gas sensors by more than 1100-fold. Lastly, the demonstration of infrared absorption spectroscopy of CO 2 using the hybrid plasmonic–MOF device proves amore » promising strategy for future on-chip gas sensing with ultra-compact size.« less

Collision-induced Absorption in the Infrared: A Data Base for Modelling Planetary and Stellar Atmospheres

NASA Technical Reports Server (NTRS)

Borysow, Aleksandra

1998-01-01

Accurate knowledge of certain collision-induced absorption continua of molecular pairs such as H2-H2, H2-He, H2-CH4, CO2-CO2, etc., is a prerequisite for most spectral analyses and modelling attempts of atmospheres of planets and cold stars. We collect and regularly update simple, state of the art computer programs for the calculation of the absorption coefficient of such molecular pairs over a broad range of temperatures and frequencies, for the various rotovibrational bands. The computational results are in agreement with the existing laboratory measurements of such absorption continua, recorded with a spectral resolution of a few wavenumbers, but reliable computational results may be expected even in the far wings, and at temperatures for which laboratory measurements do not exist. Detailed information is given concerning the systems thus studied, the temperature and frequency ranges considered, the rotovibrational bands thus modelled, and how one may obtain copies of the FORTRAN77 computer programs by e-mail.

Local surrounding of Mn in LaMn 1-xCo xO 3 compounds by means of EXAFS on Mn-K

NASA Astrophysics Data System (ADS)

Procházka, Vít; Sikora, Marcin; Kapusta, Czeslaw; Štěpánková, Helena; Chlan, Vojtěch; Knížek, Karel; Jirák, Zdeněk

2010-05-01

A systematic study of LaMn 1-xCo xO 3 perovskite series by means of X-ray absorption spectroscopy in the extended X-ray absorption fine structure (EXAFS) range of the K-absorption edge of Mn is reported. The Mn-K edge absorption measurements in the EXAFS region were performed to study the local surrounding of Mn ions. Polycrystalline powder samples of LaMn 1-xCo xO 3 ( x=0, 0.02; 0.2; 0.4; 0.5; 0.6; 0.8) prepared by solid-state reaction were used. The EXAFS spectra were analyzed with the FEFF8 computer program. The Mn-O distances of Mn to the nearest oxygen surroundings were evaluated for the samples in the series and compared with the Co-O distances obtained by EXAFS in V. Procházka et al., JMMM 310 (2007) 197 and with results of X-ray powder diffraction in C. Autret, J. Phys. Condens. Matter 17 (2005) 1601.

FY05 FM Dial Summary Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harper, Warren W.; Strasburg, Jana D.; Golovich, Elizabeth C.

2005-12-01

Pacific Northwest National Laboratory's Infrared Sensors team is focused on developing methods for standoff detection of nuclear proliferation. In FY05, PNNL continued the development of the FM DIAL (frequency-modulated differential absorption LIDAR) experiment. Additional improvements to the FM DIAL trailer provided greater stability during field campaigns which made it easier to explore new locations for field campaigns. In addition to the Hanford Townsite, successful experiments were conducted at the Marine Science Laboratory in Sequim, WA and the Nevada Test Site located outside Las Vegas, NV. The range of chemicals that can be detected by FM DIAL has also increased. Priormore » to FY05, distributed feedback quantum cascade lasers (DFB-QCL) were used in the FM DIAL experiments. With these lasers, only simple chemicals with narrow (1-2 cm-1) absorption spectra, such as CO2 and N2O, could be detected. Fabry-Perot (FP) QC lasers have much broader spectra (20-40 cm-1) which allows for the detection of larger chemicals and a wider array of chemicals that can be detected. A FP-QCL has been characterized and used during initial studies detecting DMMP (dimethyl methylphosphonate).« less

Atmospheric CO2 capture for the artificial photosynthetic system.

PubMed

Nogalska, Adrianna; Zukowska, Adrianna; Garcia-Valls, Ricard

2018-04-15

The aim of these studies is to evaluate the ambient CO 2 capture abilities of the membrane contactor system in the same conditions as leafs, such as ambient temperature, pressure and low CO 2 concentration, where the only driving force is the concentration gradient. The polysulfone membrane employed was made by a phase inversion process and characterized by ESEM micrographs which were used to determine the thickness, asymmetry and pore size. Besides, the porosity of the membrane was measured from the membrane and polysulfone density correlation and the hydrophobicity was analyzed by contact angle measurements. Moreover, the compatibility of membrane and absorbent was evaluated, in order to exclude wetting issues by meaning of swelling, dynamic contact angle and AFM analysis. The prepared membranes were introduced into a cross flow module and used as contactors between CO 2 and the absorbing media, a potassium hydroxide solution. The influence of the membrane thickness, absorbent stirring rate, solution pH and absorption time on CO 2 capture were evaluated. Absorbent solution stirring rate showed no statistically significant influence on absorption. We observed a non-linear correlation between the capture rate and the increase of absorbent solution pH as well as absorption time. The results showed that the efficiency of our CO 2 capture system is similar to stomatal carbon dioxide assimilation rate, achieving stable value of 20μmol/m 2 ·s after 1h of experiment. Copyright © 2017 Elsevier B.V. All rights reserved.

Progress on High-Energy 2-micron Solid State Laser for NASA Space-Based Wind and Carbon Dioxide Measurements

NASA Technical Reports Server (NTRS)

Singh, Upendra N.

2011-01-01

Sustained research efforts at NASA Langley Research Center during last fifteen years have resulted in significant advancement of a 2-micron diode-pumped, solid-state laser transmitter for wind and carbon dioxide measurements from ground, air and space-borne platforms. Solid-state 2-micron laser is a key subsystem for a coherent Doppler lidar that measures the horizontal and vertical wind velocities with high precision and resolution. The same laser, after a few modifications, can also be used in a Differential Absorption Lidar system for measuring atmospheric CO2 concentration profiles. Researchers at NASA Langley Research Center have developed a compact, flight capable, high energy, injection seeded, 2-micron laser transmitter for ground and airborne wind and carbon dioxide measurements. It is capable of producing 250 mJ at 10 Hz by an oscillator and one amplifier. This compact laser transmitter was integrated into a mobile trailer based coherent Doppler wind and CO2 DIAL system and was deployed during field measurement campaigns. This paper will give an overview of 2-micron solid-state laser technology development and discuss results from recent ground-based field measurements.

Development of a process for efficient use of CO2 from flue gases in the production of photosynthetic microorganisms.

PubMed

González-López, C V; Acién Fernández, F G; Fernández-Sevilla, J M; Sánchez Fernández, J F; Molina Grima, E

2012-07-01

A new methodology to use efficiently flue gases as CO(2) source in the production of photosynthetic microorganisms is proposed. The CO(2) is absorbed in an aqueous phase that is then regenerated by microalgae. Carbonated solutions could absorb up to 80% of the CO(2) from diluted gas reaching total inorganic carbon (TIC) concentrations up to 2.0 g/L. The pH of the solution was maintained at 8.0-10.0 by the bicarbonate/carbonate buffer, so it is compatible with biological regeneration. The absorption process was modeled and the kinetic parameters were determined. Anabaena sp. demonstrated to tolerate pH (8.0-10.0) and TIC (up to 2.0 g/L) conditions imposed by the absorption step. Experiments of regeneration of the liquid phase demonstrated the feasibility of the overall process, converting CO(2) into organic matter. The developed process avoids heating to regenerate the liquid whereas maximizing the efficiency of CO(2) use, which is relevant to achieve the commercial production of biofuels from microalgae. Copyright © 2012 Wiley Periodicals, Inc.

Vibrational Spectra of Molecular Ions Isolated in Solid Neon. 6. CO4(-)

DTIC Science & Technology

1991-04-04

of each of these groups are nonequivalent . Arguments are preentee indicating that this product is the CO4- anion. The infrared frequencies of the...of an alkali metal, a prominent, complicated pattern of the CO2 group be nonequivalent . The complexity of the absorption absorptions near 1600 cm...ADDRESS(ES) 10. SPONSORING/MONITORING U. S. Army Research Office AGENCY REPORT NUMBER P. 0. Box 12211 Research Triangle Park, NC 27709-2211 Ae40 ,, -69. 9’H

Solvatochromism of 9,10-phenanthrenequinone: An electronic and resonance Raman spectroscopic study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ravi Kumar, Venkatraman; Rajkumar, Nagappan; Umapathy, Siva, E-mail: umapathy@ipc.iisc.ernet.in

2015-01-14

Solvent effects play a vital role in various chemical, physical, and biological processes. To gain a fundamental understanding of the solute-solvent interactions and their implications on the energy level re-ordering and structure, UV-VIS absorption, resonance Raman spectroscopic, and density functional theory calculation studies on 9,10-phenanthrenequinone (PQ) in different solvents of diverse solvent polarity has been carried out. The solvatochromic analysis of the absorption spectra of PQ in protic dipolar solvents suggests that the longest (1n-π{sup 1}*; S{sub 1} state) and the shorter (1π-π{sup 1}*; S{sub 2} state) wavelength band undergoes a hypsochromic and bathochromic shift due to intermolecular hydrogen bondmore » weakening and strengthening, respectively. It also indicates that hydrogen bonding plays a major role in the differential solvation of the S{sub 2} state relative to the ground state. Raman excitation profiles of PQ (400–1800 cm{sup −1}) in various solvents followed their corresponding absorption spectra therefore the enhancements on resonant excitation are from single-state rather than mixed states. The hyperchromism of the longer wavelength band is attributed to intensity borrowing from the nearby allowed electronic transition through vibronic coupling. Computational calculation with C{sub 2ν} symmetry constraint on the S{sub 2} state resulted in an imaginary frequency along the low-frequency out-of-plane torsional modes involving the C=O site and therefore, we hypothesize that this mode could be involved in the vibronic coupling.« less

In situ XAFS and micro-XAFS studies on LiNi 0.8Co 0.15Al 0.05O 2 cathode material for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Nonaka, T.; Okuda, C.; Seno, Y.; Nakano, H.; Koumoto, K.; Ukyo, Y.

We have applied in situ X-ray absorption fine structure (XAFS) and in situ micro-XAFS techniques to study LiNi 0.8Co 0.15Al 0.05O 2 cathode materials in Li-ion coin cells that show various levels of capacity fading: fresh cell, cycle tested cell and aging tested cell. The change in the oxidation state and local structure of Ni and Co during charge has been investigated. Ni and Co K-edge X-ray absorption near edge structure (XANES) show that the Ni oxidation state is converted from Ni 3+ to Ni 4+ upon charging, whereas the Co oxidation state hardly changes. Ni K-edge extended X-ray absorption fine structure (EXAFS) reveals that the Jahn-Teller distorted NiO 6 octahedron turns into the symmetric octahedron upon charging, which is consistent with the change in the Ni oxidation state. Ni K-edge micro-XANES show that the oxidation of Ni proceeds homogeneously in a grain of LiNi 0.8Co 0.15Al 0.05O 2 within the special resolution of ∼2 μm, and proceeds independently of the grain size. All the behaviors of Ni and Co observed in these experiments for the fresh cell remain unchanged after the capacity fade is induced by cycle tests or aging tests, which demonstrates the considerable stability of the LiNi 0.8Co 0.15Al 0.05O 2 cathode material.

Molecular View of CO2 Capture by Polyethylenimine: Role of Structural and Dynamical Heterogeneity.

PubMed

Sharma, Pragati; Chakrabarty, Suman; Roy, Sudip; Kumar, Rajnish

2018-05-01

The molecular thermodynamics and kinetics of CO 2 sorption in Polyethylenimine (PEI) melt have been investigated systematically using GCMC and MD simulations. We elucidate presence of significant structural and dynamic heterogeneity associated with the overall absorption process. CO 2 adsorption in a PEI membrane shows a distinct two-stage process of a rapid CO 2 adsorption at the interfaces (hundreds of picoseconds) followed by a significantly slower diffusion limited release toward the interior bulk regions of PEI melt (hundreds of nanoseconds to microseconds). The spatial heterogeneity of local structural features of the PEI chains lead to significantly heterogeneous absorption characterized by clustering and trapping of CO 2 molecules that then lead to subdiffusive motion of CO 2 . In the complex interplay of interaction and entropy, the latter emerges out to be the major determining factor with significantly higher solubility of CO 2 near the interfaces despite having lower density of binding amine groups. Regions having higher free-volume (entropically favorable) viz. interfaces, pores and loops demonstrate higher CO 2 capture ability. Various local structural features of PEI conformations, for example, inter- and intrachain loops, pores of different radii, and di- or tricoordinated pores are explored for their effects on the varying CO 2 adsorption abilities.

Co-doping effects on luminescence and scintillation properties of Ce doped (Lu,Gd)3(Ga,Al)5O12 scintillator

NASA Astrophysics Data System (ADS)

Yamaguchi, Hiroaki; Kamada, Kei; Kurosawa, Shunsuke; Pejchal, Jan; Shoji, Yasuhiro; Yokota, Yuui; Ohashi, Yuji; Yoshikawa, Akira

2016-11-01

Mg co-doping effects on scintillation properties of Ce:Lu1Gd2(Ga,Al)5O12 (LGGAG) were investigated. Mg 200 ppm co-doped Ce:LGGAG single crystals were prepared by micro pulling down method. Absorption and luminescence spectra were measured together with several other scintillation characteristics, namely the scintillation decay and light yield to reveal the effect of Mg co-doping. Ce4+ charge transfer absorption was observed below 300 nm in Mg,Ce:LGGAG which is in good agreement with previous reports. The scintillation decay times were accelerated by Mg co-doping.

Modulating the band structure and sub-bandgap absorption of Co-hyperdoped silicon by co-doping with shallow-level elements

NASA Astrophysics Data System (ADS)

Dong, Xiao; Fang, Xiuxiu; Wang, Yongyong; Song, Xiaohui; Lu, Zhansheng

2018-06-01

Hyperdoped group-III elements can lower the Fermi energy in the band structures of Co-hyperdoped silicon. When the Co-to-X (X = B, Al, Ga) ratio is 2:1, the intermediate band (IB) in the bandgap includes the Fermi energy and is partially filled by electrons, which is in accordance with the requirement of an IB material. The hyperdoped X atoms can cause the blueshift of the sub-bandgap absorption of the compound compared with the material with no shallow-level elements, which is due to the enlargement of the electronic excitation energy of the Co,X-co-doped silicon.

Measurements of CO2, CH4, H2O, and HDO over a 2-km Outdoor Path with Dual-Comb Spectroscopy

NASA Astrophysics Data System (ADS)

Rieker, G. B.; Giorgetta, F. R.; Coddington, I.; Swann, W. C.; Sinclair, L. C.; Cromer, C.; Baumann, E.; Newbury, N. R.; Kofler, J.; Petron, G.; Sweeney, C.; Tans, P. P.

2013-12-01

We demonstrate simultaneous sensing of CO2, CH4, H2O, and HDO over a 2-km outdoor open air path using dual-frequency-comb absorption spectroscopy (DCS). Our implementation of the DCS technique simultaneously offers broad spectral coverage (>8 THz, 267 cm-1) and fine spectral point spacing (100 MHz, 0.0033 cm-1) with a coherent eye-safe beam. The spectrometer, which is adapted from [Zolot et al., 2012], consists of two mutually coherent Erbium-doped fiber frequency-comb lasers which create a broad spectrum of perfectly spaced narrow linewidth frequency elements (';comb teeth') near 1.6 μm. The comb light is transmitted by a telescope and active steering mirrors from the roof of the NIST Boulder laboratory to a 50-cm flat mirror located 1 km away. The return light is received by a second telescope and carried via multimode fiber to a detector. The greenhouse gas absorption attenuates the teeth from the two combs that are coincident with the relevant molecular resonant frequencies. We purposefully offset the frequencies between the two frequency combs in a Vernier-like fashion so that each pair of comb teeth from the two combs results in a unique rf heterodyne beat frequency on the photodiode. The spectral spacing between subsequent comb teeth pairs is 100 MHz, far lower than the ~4 GHz linewidths of small molecule absorption features in the atmosphere. Because of the narrow comb linewidth, there is an essentially negligible instrument lineshape. The measured absorption spectrum can thus resolve neighboring absorption features of different species, and can be compared directly with HITRAN and recent greenhouse gas absorption models developed for satellite- and ground-based carbon observatories to determine the path-integrated concentrations of the absorbing species. Measurements covering the complete 30013←00001 absorption band of CO2 and absorption features of CH4, H2O and HDO between 1.6-1.67 μm were performed under a variety of atmospheric conditions. During windy conditions when the atmosphere is well-mixed and species concentrations are stable, long-time-average data (240 min) are used to achieve high signal-to-noise ratio for careful comparisons of different spectral absorption models to the measured spectrum. Shorter five minute time resolution spectra are used to track fluctuations in atmospheric greenhouse gas concentrations over diurnal cycles and different weather conditions, and compared with simultaneous point-sampled measurements using a commercial cavity ringdown-based gas sensor. A. M. Zolot, F. R. Giorgetta, E. Baumann, J. W. Nicholson, W. C. Swann, I. Coddington, and N. R. Newbury (2012), Direct-Comb Molecular Spectroscopy with Accurate, Resolved Comb Teeth over 43 THz, Opt. Lett., 37(4), 638-640. a) Transmitted intensity spectrum over the 2-km outdoor path showing the spectral intensity variations of the combs and fine structure from gas absorption. b) Background-corrected absorbance of CO2 (blue) fitted with a Hitran model (red). The CO2 concentration measured from the fit is 408 ppm.

Measurements of spectral parameters of water-vapour transitions near 1388 and 1345 nm for accurate simulation of high-pressure absorption spectra

NASA Astrophysics Data System (ADS)

Liu, Xiang; Jeffries, Jay B.; Hanson, Ronald K.

2007-05-01

Quantitative near-infrared absorption spectroscopy of water-vapour overtone and combination bands at high pressures is complicated by pressure broadening and shifting of individual lines and the blending of neighbouring transitions. An experimental and computational methodology is developed to determine accurate high-pressure absorption spectra. This case study investigates two water-vapour transitions, one near 1388 nm (7203.9 cm-1) and the other near 1345 nm (7435.6 cm-1), for potential two-line absorption measurements of temperature in the range of 400-1050 K with a pressure varying from 5-25 atm. The required quantitative spectroscopy data (line strength, collisional broadening, and pressure-induced frequency shift) of the target transitions and their neighbours (a total of four H2O vapour transitions near 1388 nm and six transitions near 1345 nm) are measured in neat H2O vapour, H2O-air and H2O-CO2 mixtures as a function of temperature (296-1000 K) at low pressures (<800 Torr). Precise values of the line strength S(T), pressure-broadening coefficients γair(T) and \\gamma _{CO_2 } (T), and pressure-shift coefficients δair(T) and \\delta _{CO_2 } (T) for the ten transitions were inferred from the measured spectra and compared with data from HITRAN 2004. A hybrid spectroscopic database was constructed by modifying HITRAN 2004 to incorporate these values for simulation of water-vapour-absorption spectra at high pressures. Simulations using this hybrid database are in good agreement with high pressure experiments and demonstrate that data collected at modest pressures can be used to simulate high-pressure absorption spectra.

The Electronic Structure Signature of the Spin Cross-Over Transition of [Co(dpzca)2

NASA Astrophysics Data System (ADS)

Zhang, Xin; Mu, Sai; Liu, Yang; Luo, Jian; Zhang, Jian; N'Diaye, Alpha T.; Enders, Axel; Dowben, Peter A.

2018-05-01

The unoccupied electronic structure of the spin crossover molecule cobalt (II) N-(2-pyrazylcarbonyl)-2-pyrazinecarboxamide, [Co(dpzca)2] was investigated, using X-ray absorption spectroscopy (XAS) and compared with magnetometry (SQUID) measurements. The temperature dependence of the XAS and molecular magnetic susceptibility χmT are in general agreement for [Co(dpzca)2], and consistent with density functional theory (DFT). This agreement of magnetic susceptibility and X-ray absorption spectroscopy provides strong evidence that the changes in magnetic moment can be ascribed to changes in electronic structure. Calculations show the choice of Coulomb correlation energy U has a profound effect on the electronic structure of the low spin state, but has little influence on the electronic structure of the high spin state. In the temperature dependence of the XAS, there is also evidence of an X-ray induced excited state trapping for [Co(dpzca)2] at 15 K.

Non-uniform temperature and species concentration measurements in a laminar flame using multi-band infrared absorption spectroscopy

NASA Astrophysics Data System (ADS)

Ma, Liu Hao; Lau, Lok Yin; Ren, Wei

2017-03-01

We report in situ measurements of non-uniform temperature, H2O and CO2 concentration distributions in a premixed methane-air laminar flame using tunable diode laser absorption spectroscopy (TDLAS). A mid-infrared, continuous-wave, room-temperature interband cascade laser (ICL) at 4183 nm was used for the sensitive detection of CO2 at high temperature.The H2O absorption lines were exploited by one distributed feedback (DFB) diode laser at 1343 nm and one ICL at 2482 nm to achieve multi-band absorption measurements with high species concentration sensitivity, high temperature sensitivity, and immunity to variations in ambient conditions. A novel profile-fitting function was proposed to characterize the non-uniform temperature and species concentrations along the line-of-sight in the flame by detecting six absorption lines of CO2 and H2O simultaneously. The flame temperature distribution was measured at different heights above the burner (5-20 mm), and compared with the thermocouple measurement with heat-transfer correction. Our TDLAS measured temperature of the central flame was in excellent agreement (<1.5% difference) with the thermocouple data.The TDLAS results were also compared with the CFD simulations using a detailed chemical kinetics mechanism (GRI 3.0) and considering the heat loss to the surroundings.The current CFD simulation overpredicted the flame temperature in the gradient region, but was in excellent agreement with the measured temperature and species concentration in the core of the flame.

Temperature dependence of the photodissociation of CO2 from high vibrational levels: 205-230 nm imaging studies of CO(X1Σ+) and O(3P, 1D) products

NASA Astrophysics Data System (ADS)

Sutradhar, S.; Samanta, B. R.; Samanta, A. K.; Reisler, H.

2017-07-01

The 205-230 nm photodissociation of vibrationally excited CO2 at temperatures up to 1800 K was studied using Resonance Enhanced Multiphoton Ionization (REMPI) and time-sliced Velocity Map Imaging (VMI). CO2 molecules seeded in He were heated in an SiC tube attached to a pulsed valve and supersonically expanded to create a molecular beam of rotationally cooled but vibrationally hot CO2. Photodissociation was observed from vibrationally excited CO2 with internal energies up to about 20 000 cm-1, and CO(X1Σ+), O(3P), and O(1D) products were detected by REMPI. The large enhancement in the absorption cross section with increasing CO2 vibrational excitation made this investigation feasible. The internal energies of heated CO2 molecules that absorbed 230 nm radiation were estimated from the kinetic energy release (KER) distributions of CO(X1Σ+) products in v″ = 0. At 230 nm, CO2 needs to have at least 4000 cm-1 of rovibrational energy to absorb the UV radiation and produce CO(X1Σ+) + O(3P). CO2 internal energies in excess of 16 000 cm-1 were confirmed by observing O(1D) products. It is likely that initial absorption from levels with high bending excitation accesses both the A1B2 and B1A2 states, explaining the nearly isotropic angular distributions of the products. CO(X1Σ+) product internal energies were estimated from REMPI spectroscopy, and the KER distributions of the CO(X1Σ+), O(3P), and O(1D) products were obtained by VMI. The CO product internal energy distributions change with increasing CO2 temperature, suggesting that more than one dynamical pathway is involved when the internal energy of CO2 (and the corresponding available energy) increases. The KER distributions of O(1D) and O(3P) show broad internal energy distributions in the CO(X1Σ+) cofragment, extending up to the maximum allowed by energy but peaking at low KER values. Although not all the observations can be explained at this time, with the aid of available theoretical studies of CO2 VUV photodissociation and O + CO recombination, it is proposed that following UV absorption, the two lowest lying triplet states, a3B2 and b3A2, and the ground electronic state are involved in the dynamical pathways that lead to product formation.

Performance of polydimethylsiloxane membrane contactor process for selective hydrogen sulfide removal from biogas.

PubMed

Tilahun, Ebrahim; Bayrakdar, Alper; Sahinkaya, Erkan; Çalli, Bariş

2017-03-01

H 2 S in biogas affects the co-generation performance adversely by corroding some critical components within the engine and it has to be removed in order to improve the biogas quality. This work presents the use of polydimethylsiloxane (PDMS) membrane contactor for selective removal of H 2 S from the biogas. Experiments were carried out to evaluate the effects of different pH of absorption liquid, biogas flowrate and temperature on the absorption performances. The results revealed that at the lowest loading rate (91mg H 2 S/m 2 ·h) more than 98% H 2 S and 59% CO 2 absorption efficiencies were achieved. The CH 4 content in the treated gas increased from 60 to 80% with nearly 5% CH 4 loss. Increasing the pH (7-10) and loading rate (91-355mg H 2 S/m 2 ·h) enhanced the H 2 S absorption capacity, and the maximum H 2 S/CO 2 and H 2 S/CH 4 selectivity factors were 2.5 and 58, respectively. Temperature played a key role in the process and lower temperature was beneficial for intensifying H 2 S absorption performance. The highest H 2 S fluxes at pH 10 and 7 were 3.4g/m 2 ·d and 1.8g/m 2 ·d with overall mass transfer coefficients of 6.91×10 -6 and 4.99×10 -6 m/s, respectively. The results showed that moderately high H 2 S fluxes with low CH 4 loss may be achieved by using a robust and cost-effective membrane based absorption process for desulfurization of biogas. A tubular PDMS membrane contactor was tested for the first time to remove H 2 S from biogas under slightly alkaline conditions and the suggested process could be a promising for real scale applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

DCGL v2.0: an R package for unveiling differential regulation from differential co-expression.

PubMed

Yang, Jing; Yu, Hui; Liu, Bao-Hong; Zhao, Zhongming; Liu, Lei; Ma, Liang-Xiao; Li, Yi-Xue; Li, Yuan-Yuan

2013-01-01

Differential co-expression analysis (DCEA) has emerged in recent years as a novel, systematic investigation into gene expression data. While most DCEA studies or tools focus on the co-expression relationships among genes, some are developing a potentially more promising research domain, differential regulation analysis (DRA). In our previously proposed R package DCGL v1.0, we provided functions to facilitate basic differential co-expression analyses; however, the output from DCGL v1.0 could not be translated into differential regulation mechanisms in a straightforward manner. To advance from DCEA to DRA, we upgraded the DCGL package from v1.0 to v2.0. A new module named "Differential Regulation Analysis" (DRA) was designed, which consists of three major functions: DRsort, DRplot, and DRrank. DRsort selects differentially regulated genes (DRGs) and differentially regulated links (DRLs) according to the transcription factor (TF)-to-target information. DRrank prioritizes the TFs in terms of their potential relevance to the phenotype of interest. DRplot graphically visualizes differentially co-expressed links (DCLs) and/or TF-to-target links in a network context. In addition to these new modules, we streamlined the codes from v1.0. The evaluation results proved that our differential regulation analysis is able to capture the regulators relevant to the biological subject. With ample functions to facilitate differential regulation analysis, DCGL v2.0 was upgraded from a DCEA tool to a DRA tool, which may unveil the underlying differential regulation from the observed differential co-expression. DCGL v2.0 can be applied to a wide range of gene expression data in order to systematically identify novel regulators that have not yet been documented as critical. DCGL v2.0 package is available at http://cran.r-project.org/web/packages/DCGL/index.html or at our project home page http://lifecenter.sgst.cn/main/en/dcgl.jsp.

The Influence of Different Metal Ions on the Absorption Properties of Nano-Nickel Zinc Ferrite

PubMed Central

Ma, Zhijun; Mang, Changye; Weng, Xingyuan; Si, Liwei; Zhao, Haitao

2018-01-01

The hydrothermal method was used to dope different amounts of Co2+, Mn2+, and Cu2+ in nano-nickel zinc ferrite powder. X-ray diffraction (XRD), a scanning electron microscopy (TEM), and a vector network analyzer (VNA) were used to explore the influence of doping on particle size, morphology, and electromagnetic wave absorption performance. Pure nanometer cobalt nickel zinc ferrite phase was prepared using the hydrothermal method with an increasing Co2+ content. Results showed that the grain type structure changed from a spherical structure to an irregular quadrilateral structure with the average particle size increasing from 35 nm to 60 nm. The lattice constant increased from 0.8352 to 0.8404 nm with Co2+ doping. The increasing Co2+ can change the position of the absorption peak, increase the bandwidth of the absorber, and improve the performance of the materials in GHz low frequency. The doping ratio of Mn2+ can affect the size of the lattice constant, but nanocrystals are easy to reunite without improving the electromagnetic loss. However, the absorbance performance decreases. For the doping of Cu2+, there is an agglomeration phenomenon. When the doping quantity is 0.15, the absorbing wave performance becomes better. PMID:29641477

The Influence of Different Metal Ions on the Absorption Properties of Nano-Nickel Zinc Ferrite.

PubMed

Ma, Zhijun; Mang, Changye; Weng, Xingyuan; Zhang, Qi; Si, Liwei; Zhao, Haitao

2018-04-11

The hydrothermal method was used to dope different amounts of Co 2+ , Mn 2+ , and Cu 2+ in nano-nickel zinc ferrite powder. X-ray diffraction (XRD), a scanning electron microscopy (TEM), and a vector network analyzer (VNA) were used to explore the influence of doping on particle size, morphology, and electromagnetic wave absorption performance. Pure nanometer cobalt nickel zinc ferrite phase was prepared using the hydrothermal method with an increasing Co 2+ content. Results showed that the grain type structure changed from a spherical structure to an irregular quadrilateral structure with the average particle size increasing from 35 nm to 60 nm. The lattice constant increased from 0.8352 to 0.8404 nm with Co 2+ doping. The increasing Co 2+ can change the position of the absorption peak, increase the bandwidth of the absorber, and improve the performance of the materials in GHz low frequency. The doping ratio of Mn 2+ can affect the size of the lattice constant, but nanocrystals are easy to reunite without improving the electromagnetic loss. However, the absorbance performance decreases. For the doping of Cu 2+ , there is an agglomeration phenomenon. When the doping quantity is 0.15, the absorbing wave performance becomes better.

Real-time, in situ, continuous monitoring of CO in a pulverized-coal-fired power plant with a 2.3 μm laser absorption sensor

NASA Astrophysics Data System (ADS)

Chao, Xing; Jeffries, Jay B.; Hanson, Ronald K.

2013-03-01

A real-time, in situ CO sensor using 2.3 μm DFB diode laser absorption, with calibration-free wavelength-modulation-spectroscopy, was demonstrated for continuous monitoring in the boiler exhaust of a pulverized-coal-fired power plant up to temperatures of 700 K. The sensor was similar to a design demonstrated earlier in laboratory conditions, now refined to accommodate the harsh conditions of utility boilers. Measurements were performed across a 3 m path in the particulate-laden economizer exhaust of the coal-fired boiler. A 0.6 ppm detection limit with 1 s averaging was estimated from the results of a continuous 7-h-long measurement with varied excess air levels. The measured CO concentration exhibited expected inverse trends with the excess O2 concentration, which was varied between 1 and 3 %. Measured CO concentrations ranged between 6 and 200 ppm; evaluation of the data suggested a dynamic range from 6 to 10,000 ppm based on a minimum signal-to-noise ratio of ten and maximum absorbance of one. This field demonstration of a 2.3 μm laser absorption sensor for CO showed great potential for real-time combustion exhaust monitoring and control of practical combustion systems.

[Study of new blended chemical absorbents to absorb CO2].

PubMed

Wang, Jin-Lian; Fang, Meng-Xiang; Yan, Shui-Ping; Luo, Zhong-Yang; Cen, Ke-Fa

2007-11-01

Three kinds of blended absorbents were investigated on bench-scale experimental bench according to absorption rate and regeneration grade to select a reasonable additive concentration. The results show that, among methyldiethanolamine (MDEA) and piperazine (PZ) mixtures, comparing MDEA : PZ = 1 : 0.4 (m : m) with MDEA : PZ = 1 : 0.2 (m : m), the absorption rate is increased by about 70% at 0.2 mol x mol(-1). When regeneration lasting for 40 min, regeneration grade of blended absorbents with PZ concentration of 0.2, 0.4, and 0.8 is decreased to 83.06%, 77.77% and 76.67% respectively while 91.04% for PZ concentration of 0. MDEA : PZ = 1 : 0.4(m : m) is a suitable ratio for MDEA/PZ mixtures as absorption and regeneration properties of the blended absorbents are all improved. The aqueous blends with 10% primary amines and 2% tertiary amines could keep high CO2 absorption rate, and lower regeneration energy consumption. Adding 2% 2-Amino-2-methyl-1-propanol (AMP) to 10% diethanolamine (DEA), the blended amine solvents have an advantage in absorption and regeneration properties over other DEA/AMP mixtures. Blended solvents, which consist of a mixture of primary amines with a small amount of tertiary amines, have the highest absorption rate among the three. And mixed absorbents of secondary amines and a small amount of sterically hindered amines have the best regeneration property. To combine absorption and regeneration properties, blends with medium activator addition to tertiary amines are competitive.

[Growth of codoped CdWO4 crystals by Bridgman method and their optical spectra].

PubMed

Yu, Can; Xia, Hai-Ping; Wang, Dong-Jie; Chen, Hong-Bing

2011-09-01

The CdWO4 crystals with good quality in the size of Phi25 mm x 120 mm, doped with Co in 0.5% molar fraction in the raw composition, were grown by the Bridgman method by taking -70 degrees C x cm(-1) of solid-liquid interface and -0.50 mm x h(-1) growth rate. The crystal presents transparence and deep blue. The X-ray diffraction (XRD) was used to characterize the crystals. Three absorption peaks at 518, 564 and 655 nm respectively, which are attributed to the overlapping of 4 T1 (4F) --> 4A2 (4F) and 4 T1 (4F) --> 4 T1 (4P) of Co2+ octahedrons, and a wide band centered at 1 863 nm, which is attributed to 4Ti (4F) --> 4 T2 (4F), was observed. The absorption results indicated that the Co ions presented +2 valence in crystal and located within the distorted oxygen octahedrons. The crystal-field parameter D(q) and the Racah parameter B were estimated to be 990 and 726.3 cm(-1) respectively based on the absorption spectra. A fluorescence emission at 778 nm (4T1 (4P) --> 4 T1 (4F)) for codoped CdWO4 crystals was observed under excitation by 520 nm light. It can be deduced from the changes in absorption and emission intensity of different parts of crystal that the concentration of Co2+ ion in crystal increased along growing direction and the effective distribution coefficient of Co2+ ion in CdWO4 crystal is less than 1.

Bicarbonate secretion and solute absorption in forestomach of the llama.

PubMed

Rübsamen, K; Engelhardt, W V

1978-07-01

Bicarbonate appearance in the lumen and its relationship to solute absorption were studied in a Pavlov pouch in the cardiac region of the first compartment of the llama forestomach. HCO3- appearance showed no diurnal variation. HCO3- accumulation was highly dependent on the pH of the solution used. The HCO3- ion probably is formed from CO2 diffusing into the lumen from the serosal side, as a result of cell metabolism and of OH- ions. HCO3- accumulation was closely related to volatile fatty acid (VFA) absorption. The ratio of HCO3- appearance to VFA absorption depended on the pH of the solution. At a pH of 6.6, about 0.1 mol HCO3- and, at a pH of 7.8, 0.9 mol HCO3- appeared per mole absorbed VFA, indicating that at slightly alkaline pH nearly all H+ ions required for the nonionic absorption of VFA appeared to be delivered from the dissociation of H2CO3. Bicarbonate gain and VFA absorption were increased when animals were not fed for 48 h. Sodium absorption was related to VFA as well as water absorption.

Combination of first-principles molecular dynamics and XANES simulations for LiCoO2-electrolyte interfacial reactions in a lithium-ion battery

NASA Astrophysics Data System (ADS)

Tamura, Tomoyuki; Kohyama, Masanori; Ogata, Shuji

2017-07-01

We performed a first-principles molecular dynamics (FPMD) simulation of the interfacial reactions between a LiCoO2 electrode and a liquid ethylene carbonate (EC) electrolyte. For configurations during the FPMD simulation, we also performed first-principles Co K-edge x-ray absorption near-edge structure (XANES) simulations, which can properly reproduce the bulk and surface spectra of LiCoO2. We observed strong absorption of an EC molecule on the LiCoO2 {110} surface, involving ring opening of the molecule, bond formation between oxygen atoms in the molecule and surface Co ions, and emission of one surface Li ion, while all the surface Co ions remain Co3 +. The surface Co ions having the bond with an oxygen atom in the molecule showed remarkable changes in simulated K-edge spectra which are similar to those of the in situ observation under electrolyte soaking [D. Takamatsu et al., Angew. Chem., Int. Ed. 51, 11597 (2012), 10.1002/anie.201203910]. Thus, the local environmental changes of surface Co ions due to the reactions with an EC molecule can explain the experimental spectrum changes.

Solar reduction of CO.sub.2

DOEpatents

Jensen, Reed J.; Lyman, John L.; King, Joe D.; Guettler, Robert D.

2000-01-01

The red shift of the absorption spectrum of CO.sub.2 with increasing temperature permits the use of sunlight to photolyze CO.sub.2 to CO. The process of the present invention includes: preheating CO.sub.2 to near 1800 K; exposing the preheated CO.sub.2 to sunlight, whereby CO, O.sub.2 and O are produced; and cooling the hot product mix by rapid admixture with room temperature CO.sub.2. The excess thermal energy may be used to produce electricity and to heat additional CO.sub.2 for subsequent process steps. The product CO may be used to generate H.sub.2 by the shift reaction or to synthesize methanol.

Use of Inert Gases and Carbon Monoxide to Study the Possible Influence of Countercurrent Exchange on Passive Absorption from the Small Bowel

PubMed Central

Bond, John H.; Levitt, David G.; Levitt, Michael D.

1974-01-01

The purpose of the present study was to quantitate the influence of countercurrent exchange on passive absorption of highly diffusible substances from the small intestine of the rabbit. The absorption of carbon monoxide, which is tightly bound to hemoglobin and therefore cannot exchange, was compared to the absorption of four unbound gases (H2, He, CH4, and 133Xe), which should exchange freely. The degree to which the observed absorption of the unbound gases falls below that predicted from CO absorption should provide a quantitative measure of countercurrent exchange. CO uptake at high luminal Pco is flow-limited and, assuming that villus and central hemoglobin concentrations are equal, the flow that equilibrates with CO (Fco) was calculated to equal 7.24 ml/min/100 g. The observed absorption rate of the unbound gases was from two to four times greater than would have been predicted had their entire uptake been accounted for by equilibration with Fco. This is the opposite of what would occur if countercurrent exchange retarded absorption of the unbound gases. The unbound gases have both flow- and diffusion-limited components, and Fco should account for only the fraction of absorption that is flow limited. A simple model of perfusion and diffusion made it possible to calculate the fraction of the total uptake of unbound gases that was flow limited. This fraction of the total observed absorption rate was still about 1.8 times greater than predicted by CO absorption. A possible explanation for this discrepancy is that plasma skimming reduces the hemoglobin of villus blood to about 60% of that of central blood. Thus, Fco is actually about 1.7 times greater than initially calculated, and with this correction, there is close agreement between the predicted and observed rates of absorption of each of the unbound gases. We conclude that countercurrent exchange does not influence passive absorption under the conditions of this study. PMID:4436431

Intensity Modulation Techniques for Continuous-Wave Lidar for Column CO2 Measurements

NASA Astrophysics Data System (ADS)

Campbell, J. F.; Lin, B.; Obland, M. D.; Kooi, S. A.; Fan, T. F.; Meadows, B.; Browell, E. V.; Erxleben, W. H.; McGregor, D.; Dobler, J. T.; Pal, S.; O'Dell, C.

2017-12-01

Global and regional atmospheric carbon dioxide (CO2) measurements for the NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) space mission and the Atmospheric Carbon and Transport (ACT) - America project are critical for improving our understanding of global CO2 sources and sinks. Advanced Intensity-Modulated Continuous-Wave (IM-CW) lidar techniques are investigated as a means of facilitating CO2 measurements from space and airborne platforms to meet the ASCENDS and ACT-America science measurement requirements. In recent numerical, laboratory and flight experiments we have successfully used the Binary Phase Shift Keying (BPSK) and Linear Swept Frequency modulations to uniquely discriminate surface lidar returns from intermediate aerosol and cloud returns. We demonstrate the utility of BPSK to eliminate sidelobes in the range profile as a means of making Integrated Path Differential Absorption (IPDA) column CO2 measurements in the presence of optically thin clouds, thereby eliminating bias errors caused by the clouds. Furthermore, high accuracy and precision ranging to the surface as well as to the top of intermediate cloud layers, which is a requirement for the inversion of column CO2 number density measurements to column CO2 mixing ratios, has been demonstrated using new hyperfine interpolation techniques that take advantage of the periodicity of the modulation waveforms. This approach works well for both BPSK and linear swept-frequency modulation techniques and provides very high (at sub-meter level) range resolution. We compare BPSK to linear swept frequency and introduce a new technique to eliminate sidelobes in situations from linear swept frequency where the SNR is high with results that rival BPSK. We also investigate the effects of non-linear modulators, which can in some circumstances degrade the orthogonality of the waveforms, and show how to avoid this. These techniques are used in a new data processing architecture written in the C language to support the ASCENDS CarbonHawk Experiment Simulator (ACES) and ACT-America programs.

The CO2 absorption continuum by high pressure CRDS in the 1.74 μm window

NASA Astrophysics Data System (ADS)

Mondelain, D.; Campargue, A.; Čermák, P.; Gamache, R. R.; Kassi, S.; Tashkun, S. A.; Tran, H.

2017-12-01

The very weak absorption continuum of CO2 is studied by Cavity Ring Down Spectroscopy in three 20 cm-1 wide spectral intervals near the centre of the 1.74 μm window (5693-5795 cm-1). For each spectral interval, a set of room temperature spectra is recorded at pressures between 0 and 10 bar thanks to a high pressure CRDS spectrometer. The absorption continuum is retrieved after subtraction of the contributions due to Rayleigh scattering and to local lines of CO2 and water (present as an impurity in the sample) from the measured extinction. Due to some deficiencies of the CO2 HITRAN2012 line list, a composite line list had to be built on the basis of the Ames calculated line list with line positions adjusted according to the Carbon Dioxide Spectroscopic Databank and self-broadening and pressure shift coefficients calculated with the Complex Robert Bonamy method. The local line contribution of the CO2 monomer is calculated using this list and a Voigt profile truncated at ±25 cm-1 from the line centre. Line mixing effects were taken into account through the use of the impact and Energy Corrected Sudden approximations. The density dependence of the retrieved continuum absorption was found to be purely quadratic in the low frequency interval below 5710 cm-1 but a small significant linear contribution was required to reproduce the observations above this value. This linear increase is tentatively attributed to the foreign-continuum of water vapor present in CO2 sample with a relative concentration of some tens ppm. The retrieved binary coefficient is observed to vary smoothly with the wavenumber with a minimum value of 6×10-10 cm-1 amagat-2. By gathering the present data with the results reported in Kassi et al. J Quant Spectrosc Radiat Transf 2015;167:97, a recommended set of binary coefficients is provided for the 5700-5950 cm-1 region.

Microalgal-biotechnology as a platform for an integral biogas upgrading and nutrient removal from anaerobic effluents.

PubMed

Bahr, Melanie; Díaz, Ignacio; Dominguez, Antonio; González Sánchez, Armando; Muñoz, Raul

2014-01-01

The potential of a pilot high rate algal pond (HRAP) interconnected via liquid recirculation with an external absorption column for the simultaneous removal of H2S and CO2 from biogas using an alkaliphilic microalgal-bacterial consortium was evaluated. A bubble column was preferred as external absorption unit to a packed bed column based on its ease of operation, despite showing a comparable CO2 mass transfer capacity. When the combined HRAP-bubble column system was operated under continuous mode with mineral salt medium at a biogas residence time of 30 min in the absorption column, the system removed 100% of the H2S (up to 5000 ppmv) and 90% of the CO2 supplied, with O2 concentrations in the upgraded biogas below 0.2%. The use of diluted centrates as a free nutrient source resulted in a gradual decrease in CO2 removal to steady values of 40%, while H2S removal remained at 100%. The anaerobic digestion of the algal-bacterial biomass produced during biogas upgrading resulted in a CH4 yield of 0.21-0.27 L/gVS, which could satisfy up to 60% of the overall energy demand for biogas upgrading. This proof of concept study confirmed that algal-bacterial photobioreactors can support an integral upgrading without biogas contamination, with a net negative CO2 footprint, energy production, and a reduction of the eutrophication potential of the residual anaerobic effluents.

Spin and orbital states in single-layered La2-xCaxCoO4 studied by doping- and temperature-dependent near-edge x-ray absorption fine structure

NASA Astrophysics Data System (ADS)

Merz, M.; Fuchs, D.; Assmann, A.; Uebe, S.; v. Löhneysen, H.; Nagel, P.; Schuppler, S.

2011-07-01

The doping-dependent valence, orbital, and spin-state configurations of single-layered La2-xCaxCoO4 (x=0, 0.5, 1, and 1.5) were investigated with temperature-dependent near-edge x-ray absorption fine structure at the Co L2,3 and O K edges. The spectra show that in La2CoO4, the superexchange between neighboring Co2+ HS states is responsible for the strong antiferromagnetism. With increasing hole doping, the superexchange interactions between Co2+ HS ions are rapidly reduced by interlaced nonmagnetic Co3+ LS. For La1.5Ca0.5CoO4, the low Néel temperature of the samples together with the 50% Co2+ HS and 50% Co3+ LS configuration suggests a checkerboard arrangement of these ions. The spin blockade resulting from this arrangement naturally explains the high resistivity of La1.5Ca0.5CoO4. Upon further doping, Co2+ HS ions are replaced by Co3+ HS, and for LaCaCoO4 a mixture of Co3+ LS and Co3+ HS occurs. Superexchange via configuration fluctuation processes between these two species seems to induce long-range ferromagnetism, while the superexchange between adjacent Co3+ HS neighbors may lead to a competing antiferromagnetic exchange. For a doping content beyond x=1, Co4+ HS is introduced to the system at the expense of Co3+ LS, and a t2g double exchange between Co3+ HS and Co4+ HS is established, which further enhances ferromagnetic interactions and reduces resistivity. No indications for a Co3+ IS state are found throughout the La2-xCaxCoO4 doping series.

Interpretation of the prominence differential emissions measure for 3 geometries

NASA Technical Reports Server (NTRS)

Schmahl, E. J.; Orrall, F. Q.

1986-01-01

Researchers have used prominence extreme ultraviolet line intensities observed from Skylab to derive the differential emission measure Q(T) in the prominence-corona (PC) interface from 3 x 10,000 to 3 times 1 million K, including the effects of Lyman Continuum absorption. Using lines both shortward and longward of the Lyman limit, researchers have estimated the importance of absorption as function of temperature. The magnitude of the absorption, as well as its rate of increase as a function of temperature, place limits on the thread scales and the character of the interfilar medium. Researchers have calculated models based on three assumed geometries: (1) threads with hot sheaths and cool cores; (2) isothermal threads; and (3) threads with longitudinal temperature gradients along the magnetic field. Comparison of the absorption computed from these models with the observed absorption in prominences shows that none of the geometries is totally satisfactory.

The Orbiting Carbon Observatory Mission: Watching the Earth Breathe Mapping CO2 from Space

NASA Technical Reports Server (NTRS)

Boain, Ron

2007-01-01

Approach: Collect spatially resolved, high resolution spectroscopic observations of CO2 and O2 absorption in reflected sunlight. Use these data to resolve spatial and temporal variations in the column averaged CO2 dry air mole fraction, X(sub CO2) over the sunlit hemisphere. Employ independent calibration and validation approaches to produce X(sub CO2) estimates with random errors and biases no larger than 1-2 ppm (0.3-0.5%) on regional scales at monthly intervals.

Numerical simulation of the shape of laser cut for fiber and CO2 lasers

NASA Astrophysics Data System (ADS)

Zaitsev, A. V.; Ermolaev, G. V.; Polyanskiy, T. A.; Gurin, A. M.

2017-10-01

The results of numerical modeling of steel plate laser cutting with nitrogen as assist gas with consideration of heat transfer into a bulk material are presented. In this work we studied a distribution of absorbed radiation energy inside cut kerf and the difference between CO2 and fiber laser radiation propagation and absorption. The influence of secondary absorption of reflected from the cut front radiation on stability of melt hydrodynamics is discussed for different laser types.

CO2 Capture by Absorption with Potassium Carbonate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gary T. Rochelle; Eric Chen; Babatunde Oyenekan

The objective of this work is to improve the process for CO{sub 2} capture by alkanolamine absorption/stripping by developing an alternative solvent, aqueous K{sub 2}CO{sub 3} promoted by piperazine. Ethylenediamine was detected in a degraded solution of MEA/PZ solution, suggesting that piperazine is subject to oxidation. Stripper modeling has demonstrated that vacuum strippers will be more energy efficient if constructed short and fat rather than tall and skinny. The matrix stripper has been identified as a configuration that will significantly reduce energy use. Extensive measurements of CO{sub 2} solubility in 7 m MEA at 40 and 60 C have confirmedmore » the work by Jou and Mather. Corrosion of carbon steel without inhibitors increases from 19 to 181 mpy in lean solutions of 6.2 m MEA/PZ as piperazine increases from 0 to 3.1 m.« less

Structural and Spectral Characterization of Co2+- and Ni2+-DOPED CdO Powder Prepared From Solution at Room Temperature

NASA Astrophysics Data System (ADS)

Reddy, C. V.; Rao, L. V. Krishna; Satish, D. V.; Shim, J.; Ravikumar, R. V. S. S. N.

2015-11-01

The mild and simple solution method was used for the synthesis of Co2+- and Ni2+-doped CdO powders at room temperature. The prepared powders were characterized using powder X-ray diffraction, scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), optical absorption, and Fourier transform infrared spectroscopy (FTIR). From the powder X-ray diffraction patterns, it has been observed that the prepared Co2+ and Ni2+ ion-doped CdO powders belong to the cubic phase, and the evaluated average crystalline sizes of the powders are 20 and 14 nm, respectively. The SEM images and the EDS spectra show that the prepared powders are distributed over different sizes in the grain boundaries. Optical absorption studies allow determination of site symmetry of the metal ion with its ligands. The crystal field (Dq) and inter-electronic repulsion (B and C) parameters have been evaluated from the optical absorption spectra. The FTIR spectra show the characteristic fundamental vibrations of the metal oxide and CdO.

Water vapor-nitrogen absorption at CO2 laser frequencies

NASA Technical Reports Server (NTRS)

Peterson, J. C.; Thomas, M. E.; Nordstrom, R. J.; Damon, E. K.; Long, R. K.

1979-01-01

The paper reports the results of a series of pressure-broadened water vapor absorption measurements at 27 CO2 laser frequencies between 935 and 1082 kaysers. Both multiple traversal cell and optoacoustic (spectrophone) techniques were utilized together with an electronically stabilized CW CO2 laser. Comparison of the results obtained by these two methods shows remarkable agreement, indicating a precision which has not been previously achieved in pressure-broadened studies of water vapor. The data of 10.59 microns substantiate the existence of the large (greater than 200) self-broadening coefficients determined in an earlier study by McCoy. In this work, the case of water vapor in N2 at a total pressure of 1 atm has been treated.

[The Research for Trace Ammonia Escape Monitoring System Based on Tunable Diode Laser Absorption Spectroscopy].

PubMed

Zhang, Li-fang; Wang, Fei; Yu, Li-bin; Yan, Jian-hua; Cen, Ke-fa

2015-06-01

In order to on-line measure the trace ammonia slip of the commercial power plant in the future, this research seeks to measure the trace ammonia by using tunable diode laser absorption spectroscopy under ambient temperature and pressure, and at different temperatures, and the measuring temperature is about 650 K in the power plant. In recent years lasers have become commercially available in the near-infrared where the transitions are much stronger, and ammonia's spectroscopy is pretty complicated and the overlapping lines are difficult to resolve. A group of ammonia transitions near 4 433.5 cm(-1) in the v2 +v3 combination band have been thoroughly selected for detecting lower concentration by analyzing its absorption characteristic and considering other absorption interference in combustion gases where H2O and CO2 mole fraction are very large. To illustrate the potential for NH3 concentration measurements, predictions for NH3, H2O and CO2 are simultaneously simulated, NH3 absorption lines near 4 433.5 cm(-1) wavelength meet weaker H2O absorption than the commercial NH3 lines, and there is almost no CO2 absorption, all the parameters are based on the HITRAN database, and an improved detection limit was obtained for interference-free NH3 monitoring, this 2.25 μm band has line strengths several times larger than absorption lines in the 1.53 μm band which was often used by NH3 sensors for emission monitoring and analyzing. The measurement system was developed with a new Herriott cell and a heated gas cell realizing fast absorption measurements of high resolution, and combined with direct absorption and wavelenguh modulation based on tunable diode laser absorption spectroscopy at different temperatures. The lorentzian line shape is dominant at ambient temperature and pressure, and the estimated detectivity is approximately 0.225 x 10(-6) (SNR = 1) for the directed absorption spectroscopy, assuming a noise-equivalent absorbance of 1 x 10(-4). The heated cell experiments with controlled the temperature were performed to validate the sensing strategy. Here the Wavelength Modulation Spectroscopy (WMS) strategy was usually used to measure lower gas concentration for high noise immunity to the non-absorption transmission losses. The great agreement 2f signal with the calibrated concentration is within the uncertainty at different temperatures by using simple digital signal processing such as multiple averages, wavelet analysis and so on. The denoise processing has a great advantage in application and implementation over other noise suppression techniques. The result provided a good basis for trace ammonia escape detection based on tunable diode laser absorption spectroscopy.

A nonlinear merging method of analog and photon signals for CO2 detection in lower altitudes using differential absorption lidar

NASA Astrophysics Data System (ADS)

Qi, Zhong; Zhang, Teng; Han, Ge; Li, Dongcang; Ma, Xin; Gong, Wei

2017-04-01

The current acquisition system of a lidar detects return signals in two modes (i.e., analog and photon counting); resulting in the lower (below 1500 m) and upper (higher than 1100 m) atmospheric parameters need analog and photon counting signal to retrieve, respectively. Hence, a lidar cannot obtain a continuous column of the concentrations of atmospheric components. For carbon cycle studies, the range-resolved concentration of atmospheric CO2 in the lower troposphere (below 1500 m) is one of the most significant parameters that should be determined. This study proposes a novel gluing method that merges the CO2 signal detected by ground-based DIAL in the lower troposphere. Through simulation experiments, the best uniform approximation polynomial theorem is utilized to determine the transformation coefficient to correlate signals from the different modes perfectly. The experimental results (both simulation experiments and actual measurement of signals) show that the proposed method is suitable and feasible for merging data in the region below 1500 m. Hence, the photon-counting signals whose SNRs are higher than those of the analog signals can be used to retrieve atmospheric parameters at an increased near range, facilitating atmospheric soundings using ground-based lidar in various fields.

Pulsed Airborne Lidar Measurements of Atmospheric CO2 Column Absorption and Line Shapes from 3-13 km Altitudes

NASA Technical Reports Server (NTRS)

Abshire, James; Riris, Haris; Allan, Graham; Weaver, Clark; Mao, Jianping; Sun, Xiaoli; Hasselbrack, William

2010-01-01

We have developed a pulsed lidar technique for measuring the tropospheric CO2 concentrations as a candidate for NASA's planned ASCENDS space mission. Our technique uses two pulsed laser transmitters allowing simultaneous measurement of a CO2 absorption line in the 1570 nm band, O2 extinction in the Oxygen A-band and surface height and backscatter. The lidar measures the energy and time of flight of the laser echoes reflected from the atmosphere and surface. The lasers are rapidly and precisely stepped in wavelength across the CO2 line and an O2 line region during the measurement. The direct detection receiver uses a telescope and photon counting detectors, and measures the background light and energies of the laser echoes from the surface along with scattering from any aerosols in the path. The gas extinction and column densities for the CO2 and O2 gases are estimated from the ratio of the on- and off- line signals via the DIAL technique. Time gating is used to isolate the laser echo signals from the surface, and to reject laser photons scattered in the atmosphere. The time of flight of the laser pulses are also used to estimate the height of the scattering surface and to identify cases of mixed cloud and ground scattering. We have developed an airborne lidar to demonstrate the CO2 measurement from the NASA Glenn Lear-25 aircraft. The airborne lidar steps the pulsed laser's wavelength across the selected CO2 line with 20 steps per scan. The line scan rate is 450 Hz, the laser pulse widths are 1 usec, and laser pulse energy is 24 uJ. The time resolved laser backscatter is collected by a 20 cm telescope, detected by a photomultiplier and is recorded by a photon counting system. We made initial airborne measurements on flights during fall 2008. Laser backscatter and absorption measurements were made over a variety of land and water surfaces and through thin clouds. The atmospheric CO2 column measurements using the 1572.33 nm CO2 lines. Two flights were made above the US Department of Energy's (DOE) SGP ARM site at altitudes from 3-8 km. These flights were coordinated with DOE investigators who flew an in-situ CO2 sensor on a Cessna aircraft under the path. The increasing CO2 line absorptions with altitudes were evident and comparison with in-situ measurements showed agreements to 6 ppm. In spring 2009 we improved the aircraft's nadir window and during July and August we made 9 additional 2 hour long flights and measured the atmospheric CO2 absorption and line shapes using the 1572.33 nm CO2 line. Measurements were made at stepped altitudes from 3-13 km over a variety of surface types in Nebraska, Illinois, the SGP ARM site, and near and over the Chesapeake Bay in North Carolina and eastern Virginia. Strong laser signals and clear CO2 line shapes were observed at all altitudes, and some measurements were made through thin clouds. The flights over the ARM site were underflown with in-situ measurements made from the DOE Cessna. Analysis shows that the average signal levels follow predicted values, the altimetry measurements had an uncertainty of about 4 m, and that the average optical line depths follow the number density calculated from in-situ sensor readings. The Oklahoma and east coast flights were coordinated with a LaRC/ITT CO2 lidar on the LaRC UC-12 aircraft, a LaRC in-situ CO2 sensor, and the Oklahoma flights also included a JPL CO2 lidar on a Twin Otter aircraft. More details of the flights, measurements, analysis and scaling to space will be described in the presentation.

Development of a prototype for dissolved CO2 rapid measurement and preliminary tests

NASA Astrophysics Data System (ADS)

Li, Meng; Guo, Jinjia; Zhang, Zhihao; Luo, Zhao; Qin, Chuan; Zheng, Ronger

2017-10-01

The measurements of dissolved CO2 in seawater is of great significance for the study of global carbon cycle. At present, the commercial sensors used for dissolved CO2 measurements are mostly equipped with permeable membranes for the purpose of gas-liquid separation, with the advantages of easy operation, low cost, etc.. However, most of these devices measure CO2 after reaching gas equilibrium, so it takes a few minutes to respond, which limited its applications in rapid measurements. In this paper, a set of prototype was developed for the rapid measurements of dissolved CO2. The system was built basing the direct absorption TDLAS. To detect the CO2 absorption line located at 4991.26 cm-1 , a fiber-coupled DFB laser operating at 2004 nm was selected as the light source. A Herriott type multi-pass cavity with an effective optical path length of 10 m and an inner volume of 90 mL was used for absorption measurements. A detection limit of 26 μatm can be obtained with this compact cavity. To realize the rapid measurements of dissolved CO2, a degasser with high degassing rate was necessary. A hollow fiber membrane with a large permeable area used in this paper can achieve degassing rate up to 2.88 kPa/min. Benefitted from the high degassing rate of the degasser and high sensitivity of the compact TDLAS system, a rapid measurement of dissolved CO2 in water can be achieved within 1s time, and the response time of the prototype when the dissolved CO2 concentration changed abruptly in actual measurement was 15 s. To evaluate the performance of the prototype, comparison measurements were carried out with a commercial mass spectrometer. The dissolved CO2 in both seawater and tap-water was measured, and the experimental results showed good consistent trends with R2 of 0.973 and 0.931. The experimental results proved the feasibility of dissolved CO2 rapid measurement. In the near future, more system evaluation experiments will be carried out and the system will be further optimized focusing on the underwater in-situ detection system.

Technology Advancement for Active Remote Sensing of Carbon Dioxide from Space Using the ASCENDS CarbonHawk Experiment Simulator: First Results

NASA Technical Reports Server (NTRS)

Obland, Michael D.; Nehrir, Amin R.; Lin, Bing; Harrison, F. Wallace; Kooi, Susan; Choi, Yonghoon; Plant, James; Yang, Melissa; Antill, Charles; Campbell, Joel;

Phototransistors Development and their Applications to Lidar

NASA Technical Reports Server (NTRS)

Abedin, M. N.; Refaat, Tamer F.; Ismail, Syed; Singh, Upendra N.

2007-01-01

Custom-designed two-micron phototransistors have been developed using Liquid Phase Epitaxy (LPE), Molecular Beam Epitaxy (MBE) and Metal-Organic Chemical Vapor Deposition (MOCVD) techniques under Laser Risk Reduction Program (LRRP). The devices were characterized in the Detector Characterization Laboratory at NASA Langley Research Center. It appears that the performance of LPE- and MBE-grown phototransistors such as responsivity, noise-equivalent-power, and gain, are better than MOCVD-grown devices. Lidar tests have been conducted using LPE and MBE devices under the 2-micrometer CO2 Differential Absorption Lidar (DIAL) Instrument Incubator Program (IIP) at the National Center for Atmospheric Research (NCAR), Boulder, Colorado. The main focus of these tests was to examine the phototransistors performances as compared to commercial InGaAs avalanche photodiode by integrating them into the Raman-shifted Eye-safe Aerosol Lidar (REAL) operating at 1.543 micrometers. A simultaneous measurement of the atmospheric backscatter signals using the LPE phototransistors and the commercial APD demonstrated good agreement between these two devices. On the other hand, simultaneous detection of lidar backscatter signals using MBE-grown phototransistor and InGaAs APD, showed a general agreement between these two devices with a lower performance than LPE devices. These custom-built phototransistors were optimized for detection around 2-micrometer wavelength while the lidar tests were performed at 1.543 micrometers. Phototransistor operation at 2-micron will improve the performance of a lidar system operating at that wavelength. Measurements include detecting hard targets (Rocky Mountains), atmospheric structure consisting of cirrus clouds and boundary layer. These phototransistors may have potential for high sensitivity differential absorption lidar measurements of carbon dioxide and water vapor at 2.05-micrometers and 1.9-micrometers, respectively.

Development of the electrochemically regenerable carbon dioxide absorber for portable life support system application

NASA Technical Reports Server (NTRS)

Woods, R. R.; Heppner, D. B.; Marshall, R. D.; Quattrone, P. D.

1979-01-01

As the length of manned space missions increase, more ambitious extravehicular activities (EVAs) are required. For the projected longer mission the use of expendables in the portable life support system (PLSS) will become prohibited due to high launch weight and volume requirements. Therefore, the development of a regenerable CO2 absorber for the PLSS application is highly desirable. The paper discusses the concept, regeneration mechanism, performance, system design, and absorption/regeneration cycle testing of a most promising concept known as ERCA (Electrochemically Regenerable CO2 Absorber). This concept is based on absorbing CO2 into an alkaline absorbent similar to LiOH. The absorbent is an aqueous solution supported in a porous matrix which can be electrochemically regenerated on board the primary space vehicle. With the metabolic CO2 recovery the ERCA concept results in a totally regenerable CO2 scrubber. The ERCA test hardware has passed 200 absorption/regeneration cycles without performance degradation.

An in vitro study of urea, water, ion and CO2/HCO3- transport in the gastrointestinal tract of the dogfish shark (Squalus acanthias): the influence of feeding.

PubMed

Liew, Hon Jung; De Boeck, Gudrun; Wood, Chris M

2013-06-01

In vitro gut sac preparations made from the cardiac stomach (stomach 1), pyloric stomach (stomach 2), intestine (spiral valve) and colon were used to examine the impact of feeding on transport processes in the gastrointestinal tract of the dogfish shark. Preparations were made from animals that were euthanized after 1-2 weeks of fasting, or at 24-48 h after voluntary feeding on a 3% ration of teleost fish (hake). Sacs were incubated under initially symmetrical conditions with dogfish saline on both surfaces. In comparison to an earlier in vivo study, the results confirmed that feeding caused increases in H(+) secretion in both stomach sections, but an increase in Cl(-) secretion only in stomach 2. Na(+) absorption, rather than Na(+) secretion, occurred in both stomach sections after feeding. All sections of the tract absorbed water and the intestine strongly absorbed Na(+) and Cl(-), regardless of feeding condition. The results also confirmed that feeding increased water absorption in the intestine (but not in the colon), and had little influence on the handling of Ca(2+) and Mg(2+), which exhibited negligible absorption across the tract. However, K(+) was secreted in the intestine in both fasted and fed preparations. Increased intestinal water absorption occurred despite net osmolyte secretion into the mucosal saline. The largest changes occurred in urea and CO2/HCO3(-) fluxes. In fasted preparations, urea was absorbed at a low rate in all sections except the intestine, where it was secreted. Instead of an increase in intestinal urea secretion predicted from in vivo data, feeding caused a marked switch to net urea absorption. This intestinal urea transport occurred at a rate comparable to urea reabsorption rates reported at gills and kidney, and was apparently active, establishing a large serosal-to-mucosal concentration gradient. Feeding also greatly increased intestinal CO2/HCO3(-) secretion; if interpreted as HCO3(-) transport, the rates were in the upper range of those reported in marine teleosts. Phloretin (0.25 mmol l(-1), applied mucosally) completely blocked the increases in intestinal urea absorption and CO2/HCO3(-) secretion caused by feeding, but had no effect on Na(+), Cl(-) or water absorption.

Role of the Cu-ZrO 2 Interfacial Sites for Conversion of Ethanol to Ethyl Acetate and Synthesis of Methanol from CO 2 and H 2 [The Role of the Cu-ZrO 2 Interfacial Sites for Ethanol Conversion to Ethyl Acetate and Methanol Synthesis from CO 2 and H 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ro, Insoo; Liu, Yifei; Ball, Madelyn R.

Well-defined Cu catalysts containing different amounts of zirconia were synthesized by controlled surface reactions (CSRs) and atomic layer deposition methods and studied for the selective conversion of ethanol to ethyl acetate and for methanol synthesis. Selective deposition of ZrO 2 on undercoordinated Cu sites or near Cu nanoparticles via the CSR method was evidenced by UV–vis absorption spectroscopy, scanning transmission electron microscopy, and inductively coupled plasma absorption emission spectroscopy. The concentrations of Cu and Cu-ZrO 2 interfacial sites were quantified using a combination of subambient CO Fourier transform infrared spectroscopy and reactive N 2O chemisorption measurements. The oxidation states ofmore » the Cu and ZrO 2 species for these catalysts were determined using X-ray absorption near edge structure measurements, showing that these species were present primarily as Cu 0 and Zr 4+, respectively. Here, it was found that the formation of Cu-ZrO 2 interfacial sites increased the turnover frequency by an order of magnitude in both the conversion of ethanol to ethyl acetate and the synthesis of methanol from CO 2 and H 2.« less

Role of the Cu-ZrO 2 Interfacial Sites for Conversion of Ethanol to Ethyl Acetate and Synthesis of Methanol from CO 2 and H 2 [The Role of the Cu-ZrO 2 Interfacial Sites for Ethanol Conversion to Ethyl Acetate and Methanol Synthesis from CO 2 and H 2

DOE PAGES

Ro, Insoo; Liu, Yifei; Ball, Madelyn R.; ...

2016-09-06

Well-defined Cu catalysts containing different amounts of zirconia were synthesized by controlled surface reactions (CSRs) and atomic layer deposition methods and studied for the selective conversion of ethanol to ethyl acetate and for methanol synthesis. Selective deposition of ZrO 2 on undercoordinated Cu sites or near Cu nanoparticles via the CSR method was evidenced by UV–vis absorption spectroscopy, scanning transmission electron microscopy, and inductively coupled plasma absorption emission spectroscopy. The concentrations of Cu and Cu-ZrO 2 interfacial sites were quantified using a combination of subambient CO Fourier transform infrared spectroscopy and reactive N 2O chemisorption measurements. The oxidation states ofmore » the Cu and ZrO 2 species for these catalysts were determined using X-ray absorption near edge structure measurements, showing that these species were present primarily as Cu 0 and Zr 4+, respectively. Here, it was found that the formation of Cu-ZrO 2 interfacial sites increased the turnover frequency by an order of magnitude in both the conversion of ethanol to ethyl acetate and the synthesis of methanol from CO 2 and H 2.« less

Analysis of Shuttle Multispecral Infrared Radiometer measurements of the western Saudi Arabian shield.

USGS Publications Warehouse

Rowan, Lawrence C.; Goetz, Alexander F.H.; Abbott, Elsa

1987-01-01

During the November 12–14, 1981, mission of the space shuttle Columbia, the Shuttle Multispectral Infrared Radiometer (SMIRR) recorded radiances in ten channels along a 100 m wide groundtrack across the western Saudi Arabian shield. The ten channels are located in the 0.5 to 2.4 μm region, with five positioned between 2.0 and 2.40 μm for measuring absorption features that are diagnostic of OH‐bearing and CO3‐bearing">CO3‐bearing minerals. This exceptionally well exposed area consists of late Proterozoic metamorphic, intermediate to silicic intrusive, and interlayered clastic sedimentary and intermediate silicic volcanic rocks that have not been studied previously using SMIRR data. Plots or traces of unnormalized SMIRR channel ratios were examined before field studies to locate areas with high spectral contrast, especially in the 2.0 μm to 2.40 μm channels. Reflectance spectra were measured in the laboratory for rock and soil samples collected in these areas, and the mineralogic causes of the main absorption features were determined using X‐ray diffraction. Laboratory SMIRR spectra were produced by convolving the ten SMIRR filters with the laboratory spectra. Then, normalized SMIRR reflectance spectra were generated along the groundtrack using normalization coefficients calculated for a field sample representing a uniform, low‐spectral contrast area. Field evaluation shows that unnormalized SMIRR ratio traces are useful, even without specific mineralogic information, for distinguishing rocks that are characterized by Al‐OH, Mg‐OH, and/or CO3">CO3">CO3, Fe3+">Fe3+, and Fe2+ absorption features. Analysis of field samples permits suites of minerals causing absorption features to be identified. However, specific mineral identification cannot be achieved consistently using the SMIRR ratio traces or normalized SMIRR spectra, because the Al‐OH and Mg‐OH absorption features can be caused by more than one of the minerals commonly present. The normalized SMIRR spectra are especially useful for identifying subtle Al‐OH and Mg‐OH absorption features that are difficult to identify in the unnormalized ratio traces and for comparing the relative intensities of absorption features. Al‐OH absorption is related to muscovite, smectite, illite, and kaolinite, whereas Mg‐OH absorption is caused by chlorite, amphibole, and biotite. The principal sources of error in using SMIRR spectral measurements for identifying mineral groups along the orbit 27 groundtrack are inaccuracies in field location and lithologic heterogeneity that is not represented adequately by field samples. Calibration errors may account for systematic albedo and absorption intensity differences between calculated laboratory SMIRR spectra and normalized SMIRR spectra. SMIRR instrument noise and atmospheric factors appear to be less important sources of error. However, as higher spectral and spatial resolution systems are developed for mineral identification, radiometric precision and atmospheric factors will become more important.

Near-Infrared Band Strengths of Molecules Diluted in N2 and H20 Ice Mixtures Relevant to Interstellar and Planetary Ices

NASA Technical Reports Server (NTRS)

Richey, C. R.; Richey, Christina R.

2012-01-01

In order to determine the column density of a component of an ice from its infrared absorption features, the strengths of these features must be known. The peak positions, widths, profiles, and strengths of a certain ice component's infrared absorption features are affected be the overall composition of the ice. Many satellites within the solar system have surfaces that are dominated by H2O or N2 and ices in the interstellar medium (ISM) are primarily composed of H2O. The experiments presented here focus on the near-infrared absorption features of CO, CO2, CH4, and NH3 (nu=10,000-4,000/cm, lambda=1-2.5 microns) and the effects of diluting these molecules in N2 or H2O ice (mixture ratio of 5:1). This is a continuation of previous results published by our research group.

Intensity-Modulated Continuous-Wave Laser Absorption Spectrometer at 1.57 Micrometer for Atmospheric CO2 Measurements

NASA Technical Reports Server (NTRS)

Lin, Bing

2014-01-01

Understanding the earth's carbon cycle is essential for diagnosing current and predicting future climates, which requires precise global measurements of atmospheric CO2 through space missions. The Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) space mission will provide accurate global atmospheric CO2 measurements to meet carbon science requirements. The joint team of NASA Langley Research Center and ITT Exelis, Inc. proposes to use the intensity-modulated, continuous-wave (IM-CW) laser absorption spectrometer (LAS) approach for the ASCENDS mission. Prototype LAS instruments have been developed and used to demonstrate the power, signal-to-noise ratio, precision and accuracy, spectral purity, and stability of the measurement and the instrument needed for atmospheric CO2 observations from space. The ranging capability from laser platform to ground surfaces or intermediate backscatter layers is achieved by transmitted range-encoded IM laser signals. Based on the prototype instruments and current lidar technologies, space LAS systems and their CO2 column measurements are analyzed. These studies exhibit a great potential of using IM-CW LAS system for the active space CO2 mission ASCENDS.

Absorption of Carbon Dioxide in the aqueous solution of Diethanolamine (DEA) blended with 1-Butyl-1-Methylpyrrolidinium Trifluoromethanesulfonate [BmPyrr][OTf] at high pressure

NASA Astrophysics Data System (ADS)

Jamaludin, S. N.; Salleh, R. M.

2018-03-01

Solubility data of carbon dioxide (CO2) in aqueous Diethanolamine (DEA) blended with 1-Butyl-1-Methylpyrrolidinium Trifluoromethanesulfonate [Bmpyrr][OTf] were measured at temperature 313.15K, 323.15K, 333.15K and pressure from 500psi up to 700 psi. The experiments covered over the concentration range of 0-10wt% for [Bmpyrr][OTf] and 30-40wt% for DEA. The solubility of CO2 was evaluated by measuring the pressure drop in high pressure stirred absorption cell reactor. The experimental results showed that CO2 loading in all DEA-[BmPyrr][OTf] mixtures studied increases with increasing of CO2 partial pressure and temperature. It was also found that the CO2 loading capacity increase significantly as the concentration of [Bmpyrr][OTf] increases. Jou and Mather model was used to predict the solubility of CO2 in the mixtures where the experimental data were correlated as a function of temperature and CO2 partial pressure. It was found that the model was successful in predicting the solubility behavior of the aqueous DEA-[Bmpyrr][OTf] systems considered in this study.

Effect of Long Selenization Time on Co Films under a Low Temperature of 300 °C to Synthesize a Nanostructure CoSe2 and Optical Properties

NASA Astrophysics Data System (ADS)

Wu, Po-Feng; Shi, Jen-Bin; Cheng, Bo-Ci; Wu, Cheng-Han; Lee, Hsuan-Wei; Lin, Hsien-Sheng; Cheng, Fu-Chou; Chen, Kuan-Ping

2018-05-01

This work investigates a simple and non-toxic method to transform pre-deposited amorphous Co film into CoSe2 films at a fixed, low temperature of 300 °C. Single CoSe2-phase films having good crystallinity were obtained at a selenisation time ≧ 24 hours. A nanostructure CoSe2 having two different nano-morphological layers was observed. The CoSe2 films (72 hours) observed a large absorption and a direct band gap.

DISENTANGLING THE CIRCUMNUCLEAR ENVIRONS OF CENTAURUS A. II. ON THE NATURE OF THE BROAD ABSORPTION LINE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Espada, D.; Matsushita, S.; Sakamoto, K.

2010-09-01

We report on atomic gas (H I) and molecular gas (as traced by CO(2-1)) redshifted absorption features toward the nuclear regions of the closest powerful radio galaxy, Centaurus A (NGC 5128). Our H I observations using the Very Long Baseline Array allow us to discern with unprecedented sub-parsec resolution H I absorption profiles toward different positions along the 21 cm continuum jet in the inner 0.''3 (or 5.4 pc). In addition, our CO(2-1) data obtained with the Submillimeter Array probe the bulk of the absorbing molecular gas with little contamination by emission, which was not possible with previous CO single-dishmore » observations. We shed light on the physical properties of the gas in the line of sight with these data, emphasizing the still open debate about the nature of the gas that produces the broad absorption line ({approx}55 km s{sup -1}). First, the broad H I line is more prominent toward the central and brightest 21 cm continuum component than toward a region along the jet at a distance {approx}20 mas (or 0.4 pc) further from the nucleus. This indicates that the broad absorption line arises from gas located close to the nucleus, rather than from diffuse and more distant gas. Second, the different velocity components detected in the CO(2-1) absorption spectrum match well with other molecular lines, such as those of HCO{sup +}(1-0), except the broad absorption line that is detected in HCO{sup +}(1-0) (and most likely related to that of the H I). Dissociation of molecular hydrogen due to the active galactic nucleus seems to be efficient at distances r {approx}< 10 pc, which might contribute to the depth of the broad H I and molecular lines.« less

2. VIEW IN ROOM 111, ATOMIC ABSORPTION BERYLLIUM ANALYSIS LABORATORY. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. VIEW IN ROOM 111, ATOMIC ABSORPTION BERYLLIUM ANALYSIS LABORATORY. AIR FILTERS AND SWIPES ARE DISSOLVED WITH ACIDS AND THE REMAINING RESIDUES ARE SUSPENDED IN NITRIC ACID SOLUTION. THE SOLUTION IS PROCESSED THROUGH THE ATOMIC ABSORPTION SPECTROPHOTOMETER TO DETECT THE PRESENCE AND LEVELS OF BERYLLIUM. - Rocky Flats Plant, Health Physics Laboratory, On Central Avenue between Third & Fourth Streets, Golden, Jefferson County, CO

A first principles approach to the electronic properties of liquid and supercritical CO2.

PubMed

Cabral, Benedito J Costa; Rivelino, Roberto; Coutinho, Kaline; Canuto, Sylvio

2015-01-14

The electronic absorption spectra of liquid and supercritical CO2 (scCO2) are investigated by coupling a many-body energy decomposition scheme to configurations generated by Born-Oppenheimer molecular dynamics. A Frenkel exciton Hamiltonian formalism was adopted and the excitation energies were calculated with time dependent density functional theory. A red-shift of ∼ 0.2 eV relative to the gas-phase monomer is observed for the first electronic absorption maximum in liquid and scCO2. The origin of this shift, which is not very dependent on deviations from the linearity of the CO2 molecule, is mainly related to polarization effects. However, the geometry changes of the CO2 monomer induced by thermal effects and intermolecular interactions in condensed phase lead to the appearance of an average monomeric electric dipole moment〈μ〉= 0.26 ± 0.04 D that is practically the same at liquid and supercritical conditions. The predicted average quadrupole moment for both liquid and scCO2 is〈Θ〉= - 5.5 D Å, which is increased by ∼ -0.9 D Å relative to its gas-phase value. The importance of investigating the electronic properties for a better understanding of the role played by CO2 in supercritical solvation is stressed.

Two-dimensional temperature and carbon dioxide concentration profiles in atmospheric laminar diffusion flames measured by mid-infrared direct absorption spectroscopy at 4.2 μm

NASA Astrophysics Data System (ADS)

Liu, Xunchen; Zhang, Guoyong; Huang, Yan; Wang, Yizun; Qi, Fei

2018-04-01

We present a multi-line flame thermometry technique based on mid-infrared direct absorption spectroscopy of carbon dioxide at its v_3 fundamental around 4.2 μm that is particularly suitable for sooting flames. Temperature and concentration profiles of gas phase molecules in a flame are important characteristics to understand its flame structure and combustion chemistry. One of the standard laboratory flames to analyze polycyclic aromatic hydrocarbons (PAH) and soot formation is laminar non-premixed co-flow flame, but PAH and soot introduce artifact to most non-contact optical measurements. Here we report an accurate diagnostic method of the temperature and concentration profiles of CO2 in ethylene diffusion flames by measuring its v_3 vibrational fundamental. An interband cascade laser was used to probe the R-branch bandhead at 4.2 μm, which is highly sensitive to temperature change, free from soot interference and ambient background. Calibration measurement was carried out both in a low-pressure Herriott cell and an atmospheric pressure tube furnace up to 1550 K to obtain spectroscopic parameters for high-temperature spectra. In our co-flow flame measurement, two-dimensional line-of-sight optical depth of an ethylene/N2 laminar sooting flame was recorded by dual-beam absorption scheme. The axially symmetrical attenuation coefficient profile of CO2 in the co-flow flame was reconstructed from the optical depth by Abel inversion. Spatially resolved flame temperature and in situ CO2 volume fraction profiles were derived from the calibrated CO2 spectroscopic parameters and compared with temperature profiles measured by two-line atomic fluorescence.

High resolution absorption spectrum of CO2between 1750 and 2000 Å. 2. Rotational analysis of two parallel-type bands assigned to the lowest electronic transition 13B2←

NASA Astrophysics Data System (ADS)

Cossart-Magos, Claudina; Launay, Françoise; Parkin, James E.

The absorption spectrum of CO2 gas between 175 and 200 nm was photographed at high resolution some years ago. This very weak spectral region proved to be extremely rich in bands showing rotational fine structure. In Part 1 [C. Cossart-Magos, F. Launay, J. E. Parkin, Mol. Phys., 75, 835 (1992), nine perpendicular-type bands were assigned to the lowest singlet-singlet transition, 11A2 ← ν'3 (b2) vibration. Here, the parallel-type bands observed at 185.7 and 175.6 nm are assigned to the lowest triplet-singlet transition, 13B2 ← TMPH0629math005 ν'2 (a1) vibration. The assignment and the rotational and spin constant values obtained are discussed in relation to previous experimental data and ab initio calculation results on the lowest excited states of CO2. The actual role of the 13B2 state in CO2 photodissociation, O(3P)+CO(X1Σ+) recombination, and O(1D) emission quenching by CO(X) molecules is reviewed.

Laser detection of CO2 concentration in human breath at various diseases

NASA Astrophysics Data System (ADS)

Ageev, Boris G.; Nikiforova, Olga Y.

2015-12-01

Absorption spectra of human breath in 10 μm region were recorded by the use of intracavity laser photo-acoustic gas analyzer based on tunable waveguide CO2 laser. Healthy persons and patients with various diseases were studied. For determination of CO2 concentration in exhalation samples gas analyzer was calibrated by reference gaseous mixture CO2-N2. It was obtained that CO2 concentration values in human breath of healthy persons are greater than that of patients with various diseases.

Crosstalk between HIF-1 and ROCK pathways in neuronal differentiation of mesenchymal stem cells, neurospheres and in PC12 neurite outgrowth.

PubMed

Pacary, Emilie; Tixier, Emmanuelle; Coulet, Florence; Roussel, Simon; Petit, Edwige; Bernaudin, Myriam

2007-07-01

This study demonstrates that the Rho-kinase (ROCK) inhibitor, Y-27632, potentiates not only the effect of cobalt chloride (CoCl(2)) but also that of deferoxamine, another HIF-1 inducer, on mesenchymal stem cell (MSC) neuronal differentiation. HIF-1 is essential for CoCl(2)+/-Y-27632-induced MSC neuronal differentiation, since agents inhibiting HIF-1 abolish the changes of morphology and cell cycle arrest-related gene or protein expressions (p21, cyclin D1) and the increase of neuronal marker expressions (Tuj1, NSE). Y-27632 potentiates the CoCl(2)-induced decrease of cyclin D1 and nestin expressions, the increase of HIF-1 activation and EPO expression, and decreases pVHL expression. Interestingly, CoCl(2) decreases RhoA expression, an effect potentiated by Y-27632, revealing crosstalk between HIF-1 and RhoA/ROCK pathways. Moreover, we demonstrate a synergistic effect of CoCl(2) and Y-27632 on neurosphere differentiation into neurons and PC12 neurite outgrowth underlining that a co-treatment targeting both HIF-1 and ROCK pathways might be relevant to differentiate stem cells into neurons.

Co/Cr co-doped MgGa{sub 2}O{sub 4} nanoparticles: Microstructure and optical properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duan, Xiulan, E-mail: xlduan@sdu.edu.cn; Liu, Jian; Yu, Fapeng

2016-01-15

Graphical abstract: The Ga 2p{sub 3/2} spectra consist of two peaks, corresponding to Ga{sup 3+} ions placed at octahedral and tetrahedral sites, respectively. The fraction of tetrahedral Ga{sup 3+} ions (∼1117 eV) increases with increasing doping concentration. - Highlights: • Structural and properties of Co{sup 2+}/Cr{sup 3+}: MgGa{sub 2}O{sub 4} nanoparticles were characterized. • The distribution of cations was studied using XPS. • The inversion degree increased with increasing content of doping ions. • The doping concentration has also effect on absorption and emission properties. • Optical properties of nanoparticles were discussed based on the structural results. - Abstract: MgGa{submore » 2}O{sub 4} nanoparticles co-doped with Co{sup 2+}/Cr{sup 3+} ions were prepared by a citrate sol–gel method. Their microstructure and optical properties were studied using X-ray powder diffraction (XRD), infrared spectroscopy, X-ray photoelectron spectroscopy (XPS), absorption and fluorescence spectroscopy. MgGa{sub 2}O{sub 4} nanoparticles with the size of 10–30 nm were obtained when the precursor was annealed at 800 °C. Results indicated that Ga{sup 3+} and Mg{sup 2+} cations occupied the octahedral sites as well as the tetrahedral sites in samples. The inversion degree of Ga or Mg increased with increasing content of doping ions. Absorption spectra indicated that Co{sup 2+} and Cr{sup 3+} ions entered both the tetrahedral and octahedral sites of spinel structure by substituting Mg{sup 2+} and Ga{sup 3+} ions, respectively. Emission spectra of the co-doped MgGa{sub 2}O{sub 4} showed a broad emission band peaking at 700 and 680 nm, relevant to the emission characteristic of octahedral Cr{sup 3+} and tetrahedral Co{sup 2+} ions.« less

[Effects of elevated atmospheric CO2 and nitrogen application on cotton biomass, nitrogen utilization and soil urease activity].

PubMed

Lyu, Ning; Yin, Fei-hu; Chen, Yun; Gao, Zhi-jian; Liu, Yu; Shi, Lei

2015-11-01

In this study, a semi-open-top artificial climate chamber was used to study the effect of CO2 enrichment (360 and 540 µmol · mol(-1)) and nitrogen addition (0, 150, 300 and 450 kg · hm(-2)) on cotton dry matter accumulation and distribution, nitrogen absorption and soil urease activity. The results showed that the dry matter accumulation of bud, stem, leaf and the whole plant increased significantly in the higher CO2 concentration treatment irrespective of nitrogen level. The dry matter of all the detected parts of plant with 300 kg · hm(-2) nitrogen addition was significantly higher than those with the other nitrogen levels irrespective of CO2 concentration, indicating reasonable nitrogen fertilization could significantly improve cotton dry matter accumulation. Elevated CO2 concentration had significant impact on the nitrogen absorption contents of cotton bud and stem. Compared to those under CO2 concentration of 360 µmol · mol(-1), the nitrogen contents of bud and stem both increased significantly under CO2 concentration of 540 µmol · mol(-1). The nitrogen content of cotton bud in the treatment of 300 kg · hm(-2) nitrogen was the highest among the four nitrogen fertilizer treatments. While the nitrogen contents of cotton stem in the treatments of 150 kg · hm(-2) and 300 kg · hm(-2) nitrogen levels were higher than those in the treatment of 0 kg · hm(-2) and 450 kg · hm(-2) nitrogen levels. The nitrogen content of cotton leaf was significantly influenced by the in- teraction of CO2 elevation and N addition as the nitrogen content of leaf increased in the treatments of 0, 150 and 300 kg · hm(-2) nitrogen levels under the CO2 concentration of 540 µmol · mol(-1). The nitrogen content in cotton root was significantly increased with the increase of nitrogen fertilizer level under elevated CO2 (540 µmol · mol(-1)) treatment. Overall, the cotton nitrogen absorption content under the elevated CO2 (540 µmol · mol(-1)) treatment was higher than that under the ambient CO2- (360 µmol · mol(-1)) treatment. The order of nitrogen accumulation content in organs was bud > leaf > stem > root. Soil urease activity of both layers increased significantly with the elevation of CO2 concentration in all the nitrogen treatments. Under each CO2 concentration treatment, the soil urease activity in the upper layer (0-20 cm) increased significantly with nitrogen application, while the urease activity under the application of 300 kg · hm(-2) nitrogen was highest in the lower layer (20- 40 cm). The average soil urease activity in the upper layer (0-20 cm) was significantly higher than that in the lower layer (20-40 cm). This study suggested that the cotton dry matter accumulation and nitrogen absorption content were significantly increased in response to the elevated CO2 concentration (540 µmol · mol(-1)) and higher nitrogen addition (300 kg · hm(-2)).

Carbon Monoxide Releasing Molecule-A1 (CORM-A1) Improves Neurogenesis: Increase of Neuronal Differentiation Yield by Preventing Cell Death.

PubMed

Almeida, Ana S; Soares, Nuno L; Vieira, Melissa; Gramsbergen, Jan Bert; Vieira, Helena L A

2016-01-01

Cerebral ischemia and neurodegenerative diseases lead to impairment or death of neurons in the central nervous system. Stem cell based therapies are promising strategies currently under investigation. Carbon monoxide (CO) is an endogenous product of heme degradation by heme oxygenase (HO) activity. Administration of CO at low concentrations produces several beneficial effects in distinct tissues, namely anti-apoptotic and anti-inflammatory. Herein the CO role on modulation of neuronal differentiation was assessed. Three different models with increasing complexity were used: human neuroblastoma SH-S5Y5 cell line, human teratocarcinoma NT2 cell line and organotypic hippocampal slice cultures (OHSC). Cell lines were differentiated into post-mitotic neurons by treatment with retinoic acid (RA) supplemented with CO-releasing molecule A1 (CORM-A1). CORM-A1 positively modulated neuronal differentiation, since it increased final neuronal production and enhanced the expression of specific neuronal genes: Nestin, Tuj1 and MAP2. Furthermore, during neuronal differentiation process, there was an increase in proliferative cell number (ki67 mRNA expressing cells) and a decrease in cell death (lower propidium iodide (PI) uptake, limitation of caspase-3 activation and higher Bcl-2 expressing cells). CO supplementation did not increase the expression of RA receptors. In the case of SH-S5Y5 model, small amounts of reactive oxygen species (ROS) generation emerges as important signaling molecules during CO-promoted neuronal differentiation. CO's improvement of neuronal differentiation yield was validated using OHSC as ex vivo model. CORM-A1 treatment of OHSC promoted higher levels of cells expressing the neuronal marker Tuj1. Still, CORM-A1 increased cell proliferation assessed by ki67 expression and also prevented cell death, which was followed by increased Bcl-2 expression, decreased levels of active caspase-3 and PI uptake. Likewise, ROS signaling emerged as key factors in CO's increasing number of differentiated neurons in OHSC. In conclusion, CO's increasing number of differentiated neurons is a novel biological role disclosed herein. CO improves neuronal yield due to its capacity to reduce cell death, promoting an increase in proliferative population. However, one cannot disregard a direct CO's effect on specific cellular processes of neuronal differentiation. Further studies are needed to evaluate how CO can potentially modulate cell mechanisms involved in neuronal differentiation. In summary, CO appears as a promising therapeutic molecule to stimulate endogenous neurogenesis or to improve in vitro neuronal production for cell therapy strategies.

The effects of CO2 on phytoplankton community structure in the Amazon River Plume

NASA Astrophysics Data System (ADS)

Chen, T. L.; Goes, J. I.; Gomes, H. R.; McKee, K. T.

2013-12-01

The Amazon River Plume results from an enormous discharge of freshwater and organic matter into the Atlantic Ocean. It is a unique environment with a natural pCO2 gradient in the surface waters of the plume that range from 130-950 μatm. The response of coastal marine phytoplankton to increased anthropogenic CO2 emission is still unknown, hence the Amazon River Plume gradient can serve as a natural laboratory to examine the potential influence of atmospheric CO2 increases and ocean acidification on phytoplankton community composition. A two pronged study was undertaken: the first in which shipboard samples from a 2010 cruise to the Amazon River Plume were analyzed to examine the distribution of 3 major phytoplankton groups (diatoms, diatom-diazotroph associations [DDAs], and the diazotroph Trichodesmium spp.) with respect to the natural pCO2 gradient; the second in which the growth response of Thalassiosira weisflogii, a representative diatom species, was examined under experimentally manipulated CO2 conditions. Cruise data analysis showed that diatoms were found with higher cell counts around 150 μatm; DDAs seemed to dominate waters within the narrow range of 350-400 μatm CO2; and the diazotroph Trichodesmium spp. grew in a wide range of pCO2 conditions, but with higher cell counts at upwards of 500 μatm. Phytoplankton group distributions along the CO2 gradient may be due to differences in their carbon-concentrating mechanism (CCMs) efficiencies. The CO2 manipulation apparatus was assembled such that the cells were grown under three different CO2 environments. Differential growth of T. weisflogii was observed at 150, 400, and 800 ppm CO2 treatment. T. weisflogii grew at all three CO2 concentrations, reflecting diatoms' physiological flexibility and efficient CCMs. Absorption spectra analysis of pigments and Fast Repetition Rate Fluorometer analysis indicate potential changes in photosynthetic machinery with different CO2 treatments. Future CO2 manipulation experiments on representative DDA and diazotroph species will be undertaken to compare the growth responses of the 3 major phytoplankton groups to changes in CO2. Additionally, analysis on fatty acid compositions with different CO2 treatments will be done to assess potential changes in nutritive value for higher trophic levels. Underway pCO2 measurements with overlaid cell counts from the 2010 cruise data CO2 manipulation experiment data- growth curve (in vivo chlorophyll a fluorescence) for the 3 CO2 treatments

X-ray Absorption Spectroscopy Reveals an Organometallic Ni–C Bond in the CO-Treated Form of Acetyl-CoA Synthase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Can, Mehmet; Giles, Logan J.; Ragsdale, Stephen W.

Acetyl-CoA synthase (ACS) is a key enzyme in the Wood–Ljungdahl pathway of anaerobic CO 2 fixation, which has long been proposed to operate by a novel mechanism involving a series of protein-bound organometallic (Ni–CO, methyl–Ni, and acetyl–Ni) intermediates. Here we report the first direct structural evidence of the proposed metal–carbon bond. We describe the preparation of the highly active metal-replete enzyme and near-quantitative generation of the kinetically competent carbonylated intermediate. This advance has allowed a combination of Ni and Fe K-edge X-ray absorption spectroscopy and extended X-ray absorption fine structure experiments along with density functional theory calculations. The data revealmore » that CO binds to the proximal Ni of the six-metal metallocenter at the active site and undergoes dramatic structural and electronic perturbation in forming this organometallic Ni–CO intermediate. This direct identification of a Ni–carbon bond in the catalytically competent CO-bound form of the In conclusion, a cluster of ACS provides definitive experimental structural evidence supporting the proposed organometallic mechanism of anaerobic acetyl-CoA synthesis.« less

X-ray Absorption Spectroscopy Reveals an Organometallic Ni–C Bond in the CO-Treated Form of Acetyl-CoA Synthase

DOE PAGES

Can, Mehmet; Giles, Logan J.; Ragsdale, Stephen W.; ...

2017-02-10

Acetyl-CoA synthase (ACS) is a key enzyme in the Wood–Ljungdahl pathway of anaerobic CO 2 fixation, which has long been proposed to operate by a novel mechanism involving a series of protein-bound organometallic (Ni–CO, methyl–Ni, and acetyl–Ni) intermediates. Here we report the first direct structural evidence of the proposed metal–carbon bond. We describe the preparation of the highly active metal-replete enzyme and near-quantitative generation of the kinetically competent carbonylated intermediate. This advance has allowed a combination of Ni and Fe K-edge X-ray absorption spectroscopy and extended X-ray absorption fine structure experiments along with density functional theory calculations. The data revealmore » that CO binds to the proximal Ni of the six-metal metallocenter at the active site and undergoes dramatic structural and electronic perturbation in forming this organometallic Ni–CO intermediate. This direct identification of a Ni–carbon bond in the catalytically competent CO-bound form of the In conclusion, a cluster of ACS provides definitive experimental structural evidence supporting the proposed organometallic mechanism of anaerobic acetyl-CoA synthesis.« less

Synthesis of TiCr2 intermetallic compound from mechanically activated starting powders via calcio-thermic co-reduction

NASA Astrophysics Data System (ADS)

Bayat, O.; Khavandi, A. R.; Ghasemzadeh, R.

2017-05-01

Effect of mechanical activation of TiO2 and Cr2O3 oxides as starting materials was investigated for direct synthesis of TiCr2. Differential thermal analysis (DTA) indicated that increasing the ball milling time resulted in lower exothermic reaction temperatures between molten Ca-Cr2O3 and molten Ca-TiO2. A model-free Kissinger type method was applied to DTA data to evaluate the reaction kinetics. The results reveal that the activation energy of the exothermic reactions decreased with increasing the milling time. The structure, oxygen content, and average particle sizes of the obtained TiCr2 product were affected by the ball milling time of the starting materials. Increasing the milling time from 10 to 40 h decreased the average particle size and oxygen content of the obtained TiCr2 from 10 to 2 μm and from 1690 to 1290 ppm, respectively. The X-ray diffraction (XRD) results showed that TiCr2 compounds with metastable bcc phase can be produced using nano-sized starting materials, while only a slight amount of bcc phase can be obtained in the TiCr2 compounds, using micron-sized starting materials. The TiCr2 obtained by this method had a hydrogen absorption capability of 0.63 wt % and the kinetics of the hydrogen absorption increased for the 40 h milled sample.

Pressure measurement in supersonic air flow by differential absorptive laser-induced thermal acoustics.

PubMed

Hart, Roger C; Herring, G C; Balla, R Jeffrey

2007-06-15

Nonintrusive, off-body flow barometry in Mach 2 airflow has been demonstrated in a large-scale supersonic wind tunnel using seedless laser-induced thermal acoustics (LITA). The static pressure of the gas flow is determined with a novel differential absorption measurement of the ultrasonic sound produced by the LITA pump process. Simultaneously, the streamwise velocity and static gas temperature of the same spatially resolved sample volume were measured with this nonresonant time-averaged LITA technique. Mach number, temperature, and pressure have 0.2%, 0.4%, and 4% rms agreement, respectively, in comparison with known free-stream conditions.

Pressure Measurement in Supersonic Air Flow by Differential Absorptive Laser-Induced Thermal Acoustics

NASA Technical Reports Server (NTRS)

Hart, Roger C.; Herring, Gregory C.; Balla, Robert J.

2007-01-01

Nonintrusive, off-body flow barometry in Mach-2 airflow has been demonstrated in a large-scale supersonic wind tunnel using seedless laser-induced thermal acoustics (LITA). The static pressure of the gas flow is determined with a novel differential absorption measurement of the ultrasonic sound produced by the LITA pump process. Simultaneously, stream-wise velocity and static gas temperature of the same spatially-resolved sample volume were measured with this nonresonant time-averaged LITA technique. Mach number, temperature and pressure have 0.2%, 0.4%, and 4% rms agreement, respectively, in comparison with known free-stream conditions.

Effective mie-scattering and CO2 absorption in the dust-laden Martian atmosphere and its impact on radiative-convective temperature changes in the lower scale heights

NASA Technical Reports Server (NTRS)

Pallmann, A. J.

1976-01-01

A time dependent computer model of radiative-convective-conductive heat transfer in the Martian ground-atmosphere system was refined by incorporating an intermediate line strength CO2 band absorption which together with the strong-and weak-line approximation closely simulated the radiative transmission through a vertically inhomogeneous stratification. About 33,000 CO2 lines were processed to cover the spectral range of solar and planetary radiation. Absorption by silicate dust particulates, was taken into consideration to study its impact on the ground-atmosphere temperature field as a function of time. This model was subsequently attuned to IRIS, IR-radiometric and S-band occultation data. Satisfactory simulations of the measured IRIS spectra were accomplished for the dust-free condition. In the case of variable dust loads, the simulations were sufficiently fair so that some inferences into the effect of dust on temperature were justified.

[Temperature sensitivity of CO2 fluxes from rhizosphere soil mineralization and root decomposition in Pinus massoniana and Castanopsis sclerophylla forests].

PubMed

Liu, Yu; Hu, Xiao-Fei; Chen, Fu-Sheng; Yuan, Ping-Cheng

2013-06-01

Rhizospheric and non-rhizospheric soils and the absorption, transition, and storage roots were sampled from the mid-subtropical Pinus massoniana and Castanopsis sclerophylla forests to study the CO2 fluxes from soil mineralization and root decomposition in the forests. The samples were incubated in closed jars at 15 degrees C, 25 degrees C, 35 degrees C, and 45 degrees C, respectively, and alkali absorption method was applied to measure the CO2 fluxes during 53 days incubation. For the two forests, the rhizospheric effect (ratio of rhizospheric to non-rhizospheric soil) on the CO2 flux from soil mineralization across all incubation temperature ranged from 1.12 to 3.09, with a decreasing trend along incubation days. There was no significant difference in the CO2 flux from soil mineralization between the two forests at 15 degrees C, but the CO2 flux was significantly higher in P. massoniana forest than in C. sclerophylla forest at 25 degrees C and 35 degrees C, and in an opposite pattern at 45 degrees C. At all incubation temperature, the CO2 release from the absorption root decomposition was higher than that from the transition and storage roots decomposition, and was smaller in P. massoniana than in C. sclerophylla forest for all the root functional types. The Q10 values of the CO2 fluxes from the two forests were higher for soils (1.21-1.83) than for roots (0.96-1.36). No significant differences were observed in the Q10 values of the CO2 flux from soil mineralization between the two forests, but the Q10 value of the CO2 flux from root decomposition was significantly higher in P. massoniana than in C. sclerophylla forest. It was suggested that the increment of CO2 flux from soil mineralization under global warming was far higher than that from root decomposition, and for P. massoniana than for C. sclerophylla forest. In subtropics of China, the adaptability of zonal climax community to global warming would be stronger than that of pioneer community.

Density functional theory study on carbon dioxide absorption into aqueous solutions of 2-amino-2-methyl-1-propanol using a continuum solvation model.

PubMed

Yamada, Hidetaka; Matsuzaki, Yoichi; Higashii, Takayuki; Kazama, Shingo

2011-04-14

We used density functional theory (DFT) calculations with the latest continuum solvation model (SMD/IEF-PCM) to determine the mechanism of CO(2) absorption into aqueous solutions of 2-amino-2-methyl-1-propanol (AMP). Possible absorption process reactions were investigated by transition-state optimization and intrinsic reaction coordinate (IRC) calculations in the aqueous solution at the SMD/IEF-PCM/B3LYP/6-31G(d) and SMD/IEF-PCM/B3LYP/6-311++G(d,p) levels of theory to determine the absorption pathways. We show that the carbamate anion forms by a two-step reaction via a zwitterion intermediate, and this occurs faster than the formation of the bicarbonate anion. However, we also predict that the carbamate readily decomposes by a reverse reaction rather than by hydrolysis. As a result, the final product is dominated by the thermodynamically stable bicarbonate anion that forms from AMP, H(2)O, and CO(2) in a single-step termolecular reaction.

A 4 U Laser Heterodyne Radiometer for Methane (CH4) and Carbon Dioxide (CO2) Measurements from an Occultation-Viewing CubSat

NASA Technical Reports Server (NTRS)

Wilson, Emily L.; DiGregorio, A. J.; Riot, Vincent J.; Ammons, Mark S.; Bruner, WIlliam W.; Carter, Darrell; Mao, Jianping; Ramanathan, Anand; Strahan, Susan E.; Oman, Luke D.;

A potential remote sensor of CO in vehicle exhausts using 2.3 µm diode lasers

NASA Astrophysics Data System (ADS)

Wang, Jian; Maiorov, Mikhail; Jeffries, Jay B.; Garbuzov, Dmitri Z.; Connolly, John C.; Hanson, Ronald K.

2000-11-01

The potential for on-road remote sensing of vehicle exhausts using 2.3 µm diode-laser-absorption-based CO sensors is examined. Using a wavelength-modulation- spectroscopy (WMS) technique, 20 ppm sensitivity with a detection bandwidth of ≃1.5 kHz is demonstrated in laboratory experiments, which implies the ability to monitor CO emissions from even the cleanest combustion-powered vehicles. The influence of the temperature and composition of the exhaust gas on the inferred CO concentration through both linestrength and linewidth is also investigated and we propose a novel approach to reduce these effects to ±3% in the typical exhaust temperature range of 300-700 K. Thus, sensitive and remote measurements of vehicular CO effluent are possible without knowing the exact temperature or composition of the exhaust. This influence of temperature is further exploited to suggest a two-line CO2-absorption thermometry method with a large temperature sensitivity to identify cold-start vehicles.

Detection of NO sub x,C2H4 concentrations by using CO and CO2 lasers

NASA Technical Reports Server (NTRS)

Gengchen, W.; Qinxin, K.

1986-01-01

A laser, especially the infrared line tunable laser, opens up a new way to monitor the atmospheric environment, and already has gotten effective practical application. One of the most serious problems in open path remote measurement at atmospheric pressure is the broadening effect which leads to increased linewidths, spectral interferences, and, as a result, tends to reduce detection sensitivity, so measuring laser wavelengths should be selected carefully, and interaction between the measuring wavelength and gas to be measured must be known very well. Therefore, N2O, No, NO2, CH4, NH3 and C2H4 absorption properties at some lines of CO and CO2 line tunable lasers were studied. The absorption coefficients of NO, NO2, and C2H4; some results on detection of NO sub x, C2H4 concentrations in both laboratory and field; and selection of measuring wavelengths and error analysis are discussed.

Methanol ice in the protostar GL 2136

NASA Technical Reports Server (NTRS)

Skinner, C. J.; Tielens, A. G. G. M.; Barlow, M. J.; Justtanont, K.

1992-01-01

We present ground-based spectra in the 10 and 20 micron atmospheric windows of the deeply embedded protostar GL 2136. These reveal narrow absorption features at 9.7 and 8.9 microns, which we ascribe to the CO-stretch and CH3 rock (respectively) of solid methanol in grain mantles. The peak position of the 9.7 micron band implies that methanol is an important ice mantle component. However, the CH3OH/H2O abundance ratio derived from the observed column densities is only 0.1. This discrepancy suggests that the solid methanol and water ice are located in independent grain components. These independent components may reflect chemical differentiation during grain mantle formation and/or partial outgassing close to the protostar.

High pressure solubility of carbon dioxide (CO2) in aqueous solution of piperazine (PZ) activated N-methyldiethanolamine (MDEA) solvent for CO2 capture

NASA Astrophysics Data System (ADS)

Khan, Saleem Nawaz; Hailegiorgis, Sintayehu Mekuria; Man, Zakaria; Shariff, Azmi Mohd

2017-10-01

In this study, the solubility of carbon dioxide (CO2) in the aqueous solution of piperazine (PZ) activated N-methyldiethanolamine (MDEA) was investigated. In the aqueous solution the concentrations of the N-methyldiethanolamine (MDEA) and piperazine (PZ) were kept constant at 30 wt. % and 3 wt. %, respectively. The solubility experiments were carried out between the temperatures ranges of 303.15 to 333.15 K. The pressure range was selected as 2-50 bar for solubility of carbon dioxide in the aqueous solution. The solubility of the CO2 is reported in terms of CO2 loading capacity of the solvent. The loading capacity of the solvent is the ratio between the numbers of moles of CO2 absorbed to the numbers of moles of solvent used. The experimental data showed that the CO2 loading increased with increase in CO2 partial pressure, while it decreased with increase in system's temperature. It was also observed from the experimental data that the higher pressure favors the absorption process while the increased temperature hinders the absorption process of CO2 capture. The loading capacity of the investigated solvent was compared with the loading capacity of the solvents reported in the literature. The investigated solvent showed better solubility in terms of loading capacity.

Airborne differential absorption lidar system for measurements of atmospheric water vapor and aerosols

NASA Technical Reports Server (NTRS)

Carter, Arlen F.; Allen, Robert J.; Mayo, M. Neale; Butler, Carolyn F.; Grossman, Benoist E.; Ismail, Syed; Grant, William B.; Browell, Edward V.; Higdon, Noah S.; Mayor, Shane D.;

Formation of Copper Catalysts for CO 2 Reduction with High Ethylene/Methane Product Ratio Investigated with In Situ X-ray Absorption Spectroscopy

DOE PAGES

Eilert, André; Roberts, F. Sloan; Friebel, Daniel; ...

2016-04-04

Nanostructured copper cathodes are among the most efficient and selective catalysts to date for making multicarbon products from the electrochemical carbon dioxide reduction reaction (CO 2RR). We report an in situ X-ray absorption spectroscopy investigation of the formation of a copper nanocube CO 2RR catalyst with high activity that highly favors ethylene over methane production. The results show that the precursor for the copper nanocube formation is copper(I)-oxide, not copper(I)-chloride as previously assumed. A second route to an electrochemically similar material via a copper(II)–carbonate/hydroxide is also reported. In conclusion, this study highlights the importance of using oxidized copper precursors formore » constructing selective CO 2 reduction catalysts and shows the precursor oxidation state does not affect the electrocatalyst selectivity toward ethylene formation.« less

Carbonation acceleration of calcium hydroxide nanoparticles: induced by yeast fermentation

NASA Astrophysics Data System (ADS)

Lopez-Arce, Paula; Zornoza-Indart, Ainara

2015-09-01

Carbonation of Ca(OH)2 nanoparticles and consolidation of limestone are accelerated by high humidity and a yeast fermentation system that supplies a saturated atmosphere on CO2, H2O vapor and ethanol during 28 days. Nanoparticles were analyzed by X-ray diffraction and differential thermal analyses with thermogravimetry. Spectrophotometry, scanning electron microscopy analyses, and hydric and mechanical tests were also performed in stones specimens. Samples exposed to the yeast environment achieve 100 % relative CaCO3 yield, whereas at high humidity but without the yeast and under laboratory environment, relative yields of 95 % CaCO3 and 15 % CaCO3 are, respectively, reached, with white crusts and glazing left on the stone surfaces when the nanoparticles are applied at a concentration of 25 g/l. The largest increase in the drilling resistance and surface hardness values with slight increase in the capillarity absorption and desorption coefficients and with lesser stone color changes are produced at a concentration of 5 g/l, in the yeast system environment. This especially happens in stone specimens initially with bimodal pore size distributions, more amounts of pores with diameters between 0.1 and 1 µm, higher open porosity values and faster capillary coefficients. An inexpensive and reliable method based on water and yeast-sugar solution is presented to speed up carbonation of Ca(OH)2 nanoparticles used as a consolidating product to improve the mechanical properties of decayed limestone from archaeological and architectural heritage.

The hierarchical porous structure bio-char assessments produced by co-pyrolysis of municipal sewage sludge and hazelnut shell and Cu(II) adsorption kinetics.

PubMed

Zhao, Bing; Xu, Xinyang; Zeng, Fanqiang; Li, Haibo; Chen, Xi

2018-05-04

The co-pyrolysis technology was applied to municipal sewage sludge (MSS) and hazelnut shell with alkaline activating agent K 2 CO 3 under N 2 atmosphere. The innovative bio-char produced by co-pyrolysis had significant physical and chemical characteristics. The specific surface area reached 1990.23 m 2 /g, and the iodine absorption number was 1068.22 mg/g after co-pyrolysis at 850 °C. Although hazelnut shell was a kind of solid waste, it also had abundant cellulose resource, which could contribute to porous structure of bio-char during co-pyrolysis with MSS and decrease total heavy metals contents of raw material to increase security of bio-chars. Meanwhile, the residual fractions of heavy metals in bio-char were above 92.95% after co-pyrolysis at 900 °C except Cd to prevent heavy metals digestion, and the bio-char presented significant immobilization behavior from co-pyrolysis technology. Moreover, the yield and the iodine absorption number of bio-chars under different process variables were analyzed, and it was confirmed that appropriate process variables could contribute the yield and the iodine absorption number of bio-char and prevent to etch pore structure excessively to collapse. The changes of surface functional groups and crystallographic structure before and after co-pyrolysis were analyzed by FTIR and XRD, respectively. The hierarchical porous structure of bio-char was presented by SEM and N 2 adsorption-desorption isotherm. The Cu(II) adsorption capacity of the bio-char was 42.28 mg/g after 24 h, and surface functional groups acted as active binding sites for Cu(II) adsorption. Langmuir model and pseudo-second-order model can describe process of Cu(II) adsorption well.

The Far-ultraviolet "Continuum" in Protoplanetary Disk Systems. II. Carbon Monoxide Fourth Positive Emission and Absorption

NASA Astrophysics Data System (ADS)

France, Kevin; Schindhelm, Eric; Burgh, Eric B.; Herczeg, Gregory J.; Harper, Graham M.; Brown, Alexander; Green, James C.; Linsky, Jeffrey L.; Yang, Hao; Abgrall, Hervé; Ardila, David R.; Bergin, Edwin; Bethell, Thomas; Brown, Joanna M.; Calvet, Nuria; Espaillat, Catherine; Gregory, Scott G.; Hillenbrand, Lynne A.; Hussain, Gaitee; Ingleby, Laura; Johns-Krull, Christopher M.; Roueff, Evelyne; Valenti, Jeff A.; Walter, Frederick M.

2011-06-01

We exploit the high sensitivity and moderate spectral resolution of the Hubble Space Telescope Cosmic Origins Spectrograph to detect far-ultraviolet (UV) spectral features of carbon monoxide (CO) present in the inner regions of protoplanetary disks for the first time. We present spectra of the classical T Tauri stars HN Tau, RECX-11, and V4046 Sgr, representative of a range of CO radiative processes. HN Tau shows CO bands in absorption against the accretion continuum. The CO absorption most likely arises in warm inner disk gas. We measure a CO column density and rotational excitation temperature of N(CO) = (2 ± 1) × 1017 cm-2 and T rot(CO) 500 ± 200 K for the absorbing gas. We also detect CO A-X band emission in RECX-11 and V4046 Sgr, excited by UV line photons, predominantly H I Lyα. All three objects show emission from CO bands at λ > 1560 Å, which may be excited by a combination of UV photons and collisions with non-thermal electrons. In previous observations these emission processes were not accounted for due to blending with emission from the accretion shock, collisionally excited H2, and photo-excited H2, all of which appeared as a "continuum" whose components could not be separated. The CO emission spectrum is strongly dependent upon the shape of the incident stellar Lyα emission profile. We find CO parameters in the range: N(CO) ~ 1018-1019 cm-2, T rot(CO) >~ 300 K for the Lyα-pumped emission. We combine these results with recent work on photo-excited and collisionally excited H2 emission, concluding that the observations of UV-emitting CO and H2 are consistent with a common spatial origin. We suggest that the CO/H2 ratio (≡ N(CO)/N(H2)) in the inner disk is ~1, a transition between the much lower interstellar value and the higher value observed in solar system comets today, a result that will require future observational and theoretical study to confirm. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

Specific features of the atomic structure of metallic layers of multilayered (CoFeZr/SiO2)32 and (CoFeZr/ a-Si)40 nanostructures with different interlayers

NASA Astrophysics Data System (ADS)

Domashevskaya, E. P.; Guda, A. A.; Chernyshev, A. V.; Sitnikov, V. G.

2017-02-01

Multilayered nanostructures (MN) were prepared by ion-beam successive sputtering from two targets, one of which was a metallic Co45Fe45Zr10 alloy plate and another target was a quartz (SiO2) or silicon plate on the surface of a rotating glass-ceramic substrate in an argon atmosphere. The Co and Fe K edges X-ray absorption fine structure of XANES in the (CoFeZr/SiO2)32 sample with oxide interlayers was similar to XANES of metallic Fe foil. This indicated the existence in metallic layers of multilayered CoFeZr nanocrystals with a local environment similar to the atomic environment in solid solutions on the base of bcc Fe structure, which is also confirmed by XRD data. XANES near the Co and Fe K edges absorption in another multilayered nanostructure with silicon interlayers (CoFeZr/ a-Si)40 differs from XANES of MN with dielectric SiO2 interlayer, which demonstrates a dominant influence of the Fe-Si and Co-Si bonds in the local environment of 3 d Co and Fe metals when they form CoFeSi-type silicide phases in thinner bilayers of this MN.

A flow-system comparison of the reactivities of calcium superoxide and potassium superoxide with carbon dioxide and water vapor

NASA Technical Reports Server (NTRS)

Wood, P. C.; Ballou, E. V.; Spitze, L. A.; Wydeven, T.

1982-01-01

A single pass flow system was used to test the reactivity of calcium superoxide with respiratory gases and the performance was compared to that of potassium superoxide. The KO2 system is used by coal miners as a self-contained unit in rescue operations. Particular attention was given to the reactivity with carbon dioxide and water vapor at different temperatures and partial pressures of oxygen, carbon dioxide, and water vapor. The calcium superoxide beds were found to absorb CO2 and H2O vapor, releasing O2. The KO2 bed, however, released O2 at twice the rate of CO2 absorption at 37 C. It is concluded that the calcium superoxide material is not a suitable replacement for the KO2 bed, although Ca(O2)2 may be added to the KO2 bed to enhance the CO2 absorption.

Mid-infrared GaSb-based resonant tunneling diode photodetectors for gas sensing applications

NASA Astrophysics Data System (ADS)

Rothmayr, F.; Pfenning, A.; Kistner, C.; Koeth, J.; Knebl, G.; Schade, A.; Krueger, S.; Worschech, L.; Hartmann, F.; Höfling, S.

2018-04-01

We present resonant tunneling diode-photodetectors (RTD-PDs) with GaAs0.15Sb0.85/AlAs0.1Sb0.9 double barrier structures combined with an additional quaternary Ga0.64In0.36As0.33Sb0.67 absorption layer covering the fingerprint absorption lines of various gases in the mid-infrared wavelength spectral region. The absorption layer cut-off wavelength is determined to be 3.5 μm, and the RTD-PDs show peak-to-valley current ratios up to 4.3 with a peak current density of 12 A/cm-2. The incorporation of the quaternary absorption layer enables the RTD-PDs to be sensitive to illumination with light up to the absorption lines of HCl at 3395 nm. At this wavelength, the detector shows a responsivity of 6.3 mA/W. At the absorption lines of CO2 and CO at 2004 nm and 2330 nm, respectively, the RTD-PDs reach responsivities up to 0.97 A/W. Thus, RTD-PDs pave the way towards high sensitive mid-infrared detectors that can be utilized in tunable laser absorption spectroscopy.

Soft x-ray absorption spectra of ilmenite family.

PubMed

Agui, A; Mizumaki, M; Saitoh, Y; Matsushita, T; Nakatani, T; Fukaya, A; Torikai, E

2001-03-01

We have carried out soft x-ray absorption spectroscopy to study the electronic structure of ilmenite family, such as MnTiO3, FeTiO3, and CoTiO3 at the soft x-ray beamline, BL23SU, at the SPring-8. The Ti and M L2,3 absorption spectra of MTiO3 (M=Mn, Fe, and Co) show spectra of Ti4+ and M2+ electron configurations, respectively. Except the Fe L2,3 spectrum, those spectra were understood within the O(h) symmetry around the transition metal ions. The Fe L3-edge spectrum clearly shows a doublet peak at the L3 edge, which is attributed to Fe2+ state, moreover the very high-resolution the L-edge spectra of transition metals show fine structures. The spectra of those ilmenites are compared.

Adjustable 3-D structure with enhanced interfaces and junctions towards microwave response using FeCo/C core-shell nanocomposites.

PubMed

Li, Daoran; Liang, Xiaohui; Liu, Wei; Ma, Jianna; Zhang, Yanan; Ji, Guangbin; Meng, Wei

2017-12-01

In this work, the 3-D honeycomb-like FeCo/C nanocomposites were synthesized through the carbon thermal reduction under an inert atmosphere. The enhanced microwave absorption properties of the composites were mainly attributed to the unique three dimensional structure of the FeCo/C nanocomposites, abundant interfaces and junctions, and the appropriate impedance matching. The Cole-Cole semicircles proved the sufficient dielectric relaxation process. The sample calcinated at 600°C for 4h showed the best microwave absorption properties. A maximum reflection loss of -54.6dB was achieved at 10.8GHz with a thickness of 2.3mm and the frequency bandwidth was as large as 5.3GHz. The results showed that the as-prepared FeCo/C nanocomposite could be a potential candidate for microwave absorption. Copyright © 2017 Elsevier Inc. All rights reserved.

Structural, electronic and optical properties of CO adsorbed on the defective anatase TiO2 (101) surface; a DFT study

NASA Astrophysics Data System (ADS)

Rafique, Muhammad; Shuai, Yong; Hassan, Muhammad

2017-08-01

This paper illustrates the study of stable structural, electronic and optical properties of carbon mono oxide (CO) molecule adsorbed on pure anatase TiO2 (101) surface and CO molecule adsorbed on defective anatase TiO2 (101) surface containing oxygen (O) atom subsurface vacancy using first-principles study calculations based on density functional theory (DFT) method. A foreign molecule CO was added in the interstitial space of anatase TiO2 (101) surface. It was observed that, adsorption of CO molecule is not favorable on pure anatase TiO2 (101) surface, however adsorption process is improved when subsurface contains O atom vacancy defect. In case of anatase TiO2 (101) surface containing subsurface vacancy, adsorption process is exothermic, resulting in stable structures. The adsorption energies calculated for CO molecules adsorbed at O2c site, at defect site and at Ti5c site of anatase surface containing subsurface O vacancy are 0.16 eV (at O2c), 0.32 eV (at defect site) and 0.43 eV (at Ti5c) site. DOS and PDOS plots are calculated for all the structures. Results indicated that CO molecule adsorption introduces surface states at the Fermi energy level (EF) as shown in partial density of states (PDOS) plots. The dielectric matrix and absorption coefficient (α) for defective anatase TiO2 (101) surface, CO adsorbed at O2c site, at defect site and at Ti5C site of anatase TiO2 (101) surface containing O atom subsurface vacancy has been calculated within the random phase approximation (RPA) using VASP (Vienna ab-initio simulation package) code. It was observed that upon CO adsorption at defective anatase surface, real and imaginary dielectric function peaks were shifted towards lower energy level and a small absorption peak was observed at 1.1 eV energy level which is not present in case of defective anatase (101) surface. CO adsorption produces a red shift in the absorption spectrum of anatase TiO2 (101) surface containing subsurface O atom vacancy.

Nitrogen balance for wheat canopies (Triticum aestivum cv. Veery 10) grown under elevated and ambient CO2 concentrations

NASA Technical Reports Server (NTRS)

Smart, D. R.; Ritchie, K.; Bloom, A. J.; Bugbee, B. B.

1998-01-01

We examined the hypothesis that elevated CO2 concentration would increase NO3- absorption and assimilation using intact wheat canopies (Triticum aestivum cv. Veery 10). Nitrate consumption, the sum of plant absorption and nitrogen loss, was continuously monitored for 23 d following germination under two CO2 concentrations (360 and 1000 micromol mol-1 CO2) and two root zone NO3- concentrations (100 and 1000 mmol m3 NO3-). The plants were grown at high density (1780 m-2) in a 28 m3 controlled environment chamber using solution culture techniques. Wheat responded to 1000 micromol mol-1 CO2 by increasing carbon allocation to root biomass production. Elevated CO2 also increased root zone NO3- consumption, but most of this increase did not result in higher biomass nitrogen. Rather, nitrogen loss accounted for the greatest part of the difference in NO3- consumption between the elevated and ambient [CO2] treatments. The total amount of NO3(-)-N absorbed by roots or the amount of NO3(-)-N assimilated per unit area did not significantly differ between elevated and ambient [CO2] treatments. Instead, specific leaf organic nitrogen content declined, and NO3- accumulated in canopies growing under 1000 micromol mol-1 CO2. Our results indicated that 1000 micromol mol-1 CO2 diminished NO3- assimilation. If NO3- assimilation were impaired by high [CO2], then this offers an explanation for why organic nitrogen contents are often observed to decline in elevated [CO2] environments.

Chemical composition of Lycium europaeum fruit oil obtained by supercritical CO2 extraction and evaluation of its antioxidant activity, cytotoxicity and cell absorption.

PubMed

Rosa, Antonella; Maxia, Andrea; Putzu, Danilo; Atzeri, Angela; Era, Benedetta; Fais, Antonella; Sanna, Cinzia; Piras, Alessandra

2017-09-01

We studied the total phenols and flavonoids, liposoluble antioxidants, fatty acid and triacylglycerol profiles, and oxidative status of oil obtained from Lycium europaeum fruits following supercritical CO 2 extraction (at 30MPa and 40°C). Linoleic (52%), palmitic (18%), oleic (13%), and α-linolenic (6%) were the main oil fatty acids, while trilinolein and palmitodilinolein/oleodilinolein represented the main triacylglycerols. The oil was characterized by high levels of all-trans-zeaxanthin and all-trans-β-carotene (755 and 332μg/g of oil, respectively), α-tocopherol (308μg/g of oil), total phenols (13.6mg gallic acid equivalents/g of oil), and total flavonoids (6.8mg quercetin equivalents/g of oil). The oil showed radical scavenging activities (ABTS and DPPH assays) and inhibited Caco-2 cell growth. Moreover, the incubation of differentiated Caco-2 cells with a non-toxic oil concentration (100μg/mL) induced a significant intracellular accumulation of essential fatty acids. The results qualify L. europaeum oil as a potential source for food/pharmaceutical applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

Changes in migration mode of brine and supercritical CO2 in imbibition process under steady flow state of very slow fluid velocities

NASA Astrophysics Data System (ADS)

Kogure, Tetsuya; Zhang, Yi; Nishizawa, Osamu; Xue, Ziqiu

2018-05-01

Relative permeability curves and flow mechanisms of CO2 and brine in Berea sandstone were investigated during a two-phase flow imbibition process, where CO2 saturation in the rock decreased from 55 per cent to 9 per cent by stepwise decrease of CO2/brine injection ratios. Total fluid flow velocity was 4.25 × 10-6 m/s, corresponding to the capillary number of order ˜10-8 for CO2 flow. The relative permeability curves showed a slight hysteresis compared to those during the drainage process. Local CO2 saturation and the differential pressure showed temporal fluctuations when the average differential pressure showed constant values or very small trends. The fluctuations in local CO2 saturation correlate with local porosity distributions. The differential pressure between the inlet and outlet ends showed the largest fluctuation when the CO2/brine ratio equals to one. A final brine-only injection resulted in more CO2 trapped within low porosity zones. These results suggest important roles of ganglion dynamics in the low flow rate ranges, where fluid pathways undergo repetitive brine snap-off and coalescence of CO2 ganglia that causes morphological changes in distributions of CO2 pathways.

Tunable single-longitudinal-mode operation of an injection-locked TEA CO2 laser. [ozone absorption spectroscopy

NASA Technical Reports Server (NTRS)

Megie, G.; Menzies, R. T.

1979-01-01

The tunable single-longitudinal-mode operation of a TEA CO2 laser by an injection technique using a CW waveguide laser as the master oscillator is reported. With the experimental arrangement described, in which the waveguide laser frequency is tuned to correspond to one of the oscillating longitudinal modes of the TEA laser, single-longitudinal-mode operation was achieved with no apparent reduction in the TEA output energy, on various CO2 lines with frequency offsets from the line center as large as 300 MHz. The capability of this technique for high-resolution spectroscopy or atmospheric lidar studies is demonstrated by the recording of the absorption spectrum of a strong ozone line.

High-resolution reflectance spectra of Mars in the 2.3-μm region: evidence for the mineral scapolite

USGS Publications Warehouse

Clark, Roger N.; Swayze, Gregg A.; Singer, Robert B.; Pollack, James B.

1990-01-01

patially resolved reflectance spectra of Mars in the 2.2- to 2.4-μm spectral region were obtained in August 1988 using the NASA 3-m Infrared Telescope Facility. The spectra show weak absorption features due to Martian atmospheric carbon monoxide and a surface mineral. Both CO and the mineral absorptions are composed of overlapping narrow features, but in many locations, such as Hellas, Chryse, Eden, and Moab, the mineral absorptions are quite strong, at least 3 times stronger than at the most absorbing wavelengths of CO near 2.33 μm. Therefore CO complicates the analysis of the surface mineral but does not always overwhelm its signature. Model removal of the Martian atmospheric CO has been performed, and the remaining absorption bands are identified as scapolite. Relatively strong absorptions that match bands in the spectrum of scapolite and have little or no CO absorption interference are seen near 2.41, 2.39, and 2.29 μm. Absorption also occurs at the scapolite bands at 2.36 and 2.33 μm, but the analysis is complicated by uncertainty in the atmospheric CO removal at these wavelengths. Weaker scapolite bands are seen at 2.44 and 2.23 μm where there is virtually no atmospheric interference. The scapolite bands observed on Mars are due to HCO3− and HSO4− ions in the scapolite structure. The bicarbonate and bisulfate contents appear to vary with location: the scapolite in Hellas is more bisulfate-rich relative to that in the Chryse/Moab/Eden area. Other locations contain little (Arabia, Syrtis Major, Hellespontica, and Isidis) or no scapolite (e.g., Margaritifer, Ausonia, and Erythraeum). The calculated abundances are unconstrained because the amounts of HCO3− and HSO4− in the Martian scapolites as well as their grain sizes are not known. If the scapolites contain about 3 wt % of each, near the maximum possible, the scapolite abundances probably range from about 5 wt % scapolite at Eden and Hellas; 3–5% at Chryse, Moab, and Oxia Palus; 2–3% at Arabia, Syrtis Major, and Isidis; to less than 2% at Hellespontica, Syrtis Minor, and Margaritifer, assuming a relatively large grain size of 50–100 μm. If the characteristic grain sizes are smaller or the HCO3− and HSO4− contents are lower, the scapolite abundances required to match the observed band depths would be higher. The mineral bands are apparent in many of the Mars spectra measured, so it appears to be widely but not uniformly distributed. The newly observed fine structure also varies greatly in both depth and spectral detail with location on Mars. Thus there appears to be regional variations in composition. The mineral phases appear to reflect local or regional geology and are not primarily contained in the homogeneous, globally redistributed aeolian dust. Higher spectral resolution Martian spectra in the 2.3-μm region as well as at 3.9 μm are needed to confirm the scapolite identification and to constrain its abundance.

Impulsive Collision Dynamics of CO Super Rotors from an Optical Centrifuge.

PubMed

Murray, Matthew J; Ogden, Hannah M; Toro, Carlos; Liu, Qingnan; Mullin, Amy S

2016-11-18

We report state-resolved collision dynamics for CO molecules prepared in an optical centrifuge and measured with high-resolution transient IR absorption spectroscopy. Time-resolved polarization-sensitive measurements of excited CO molecules in the J=29 rotational state reveal that the oriented angular momentum of CO rotors is relaxed by impulsive collisions. The translational energy gains for molecules in the initial plane of rotation are threefold larger than for randomized angular momentum orientations, indicating the presence of anisotropic kinetic energy. The transient data show enhanced population for CO molecules in the initial plane of rotation immediately following the optical centrifuge pulse. A comparison with previous CO 2 super rotor studies illustrates the behavior of molecular gyroscopes; spatial reorientation of CO 2 J=76 rotors takes substantially longer than that for CO J=29 rotors, despite similarities in classical rotational period and rotational energy gap. High-resolution transient IR absorption measurements of the CO J=29-39 rotational states show that the collisional depopulation rates increase with J quantum number. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Capteur de CO{2} à fibres optiques par absorption moléculaire à 4,3 μm

NASA Astrophysics Data System (ADS)

Bendamardji, S.; Alayli, Y.; Huard, S.

1996-04-01

This paper describes a remote optical fibre sensor for the carbon dioxide detection by molecular absorption in the near infrared (4.3 μm) corresponding to fundamental mode ν3. To overcome the problem of the strong attenuation signal of optical fibre in the near infrared, we have used the opto-suppling technique which changes the working wavelength from 4.3 μm to 860 nm and permits the use of standard optical fibre 50/125. The simulation of absorption has been obtained by original modelisation of the absorption spectrum and the establishment of the calibration curves takes to the sensor to detect a partial pressures greater than 100 μbar with a minimal error margin of 100 μbar, which is acceptable considering the future use of the device. The sensor has been designed to monitor the CO{2} rate in enriched greenhouses. Cet article décrit un capteur à fibres optiques de gaz carbonique par absorption moléculaire dans l'infrarouge moyen (4,3 μm) correspondant au mode fondamental ν3. La liaison entre le site de mesure et le site de contrôle est assurée par un fibre optique standard 50/125 après une transposition de longueur d'onde de 4,3 μm à 860 nm par opto-alimentation. La simulation de l'absorption a été obtenue par modélisation originale du spectre d'absorption et l'établissement des courbes d'étalonnage prévoit une marge d'erreur minimale de 100 μbar, ce qui est suffisant pour l'application du dispositif à la régulation de taux CO{2} dans les serres agricoles enrichies par de gaz.

Advanced Intensity-Modulation Continuous-Wave Lidar Techniques for Column CO2 Measurements

NASA Astrophysics Data System (ADS)

Campbell, J. F.; Lin, B.; Obland, M. D.; Liu, Z.; Kooi, S. A.; Fan, T. F.; Nehrir, A. R.; Meadows, B.; Browell, E. V.

2016-12-01

Advanced Intensity-Modulation Continuous-Wave Lidar Techniques for Column CO2 MeasurementsJoel F. Campbell1, Bing Lin1, Michael D. Obland1, Zhaoyan Liu1, Susan Kooi2, Tai-Fang Fan2, Amin R. Nehrir1, Byron Meadows1, Edward V. Browell31NASA Langley Research Center, Hampton, VA 23681 2SSAI, NASA Langley Research Center, Hampton, VA 23681 3STARSS-II Affiliate, NASA Langley Research Center, Hampton, VA 23681 AbstractGlobal and regional atmospheric carbon dioxide (CO2) measurements for the NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) space mission and the Atmospheric Carbon and Transport (ACT) - America project are critical for improving our understanding of global CO2 sources and sinks. Advanced Intensity-Modulated Continuous-Wave (IM-CW) lidar techniques are investigated as a means of facilitating CO2 measurements from space and airborne platforms to meet the ASCENDS and ACT-America science measurement requirements. In recent numerical, laboratory and flight experiments we have successfully used the Binary Phase Shift Keying (BPSK) modulation technique to uniquely discriminate surface lidar returns from intermediate aerosol and cloud returns. We demonstrate the utility of BPSK to eliminate sidelobes in the range profile as a means of making Integrated Path Differential Absorption (IPDA) column CO2 measurements in the presence of optically thin clouds, thereby minimizing bias errors caused by the clouds. Furthermore, high accuracy and precision ranging to the surface as well as to the top of intermediate cloud layers, which is a requirement for the inversion of column CO2 number density measurements to column CO2 mixing ratios, has been demonstrated using new sub-meter hyperfine interpolation techniques that takes advantage of the periodicity of the modulation waveforms. The BPSK technique under investigation has excellent auto-correlation properties while possessing a finite bandwidth. These techniques are used in a new data processing architecture written in the C language to support the ASCENDS CarbonHawk Experiment Simulator (ACES) and ACT-America programs. This software is about an order of magnitude faster than the Mathematica code previously used and uses multithreaded parallel processing code that takes advantage of multicore processors.

Laser-heated thruster

NASA Technical Reports Server (NTRS)

Kemp, N. H.; Lewis, P. F.

1980-01-01

The development of a computer program for the design of the thrust chamber for a CW laser heated thruster was examined. Hydrodgen was employed as the propellant gas and high temperature absorber. The laser absorption coefficient of the mixture/laser radiation combination is given in temperature and species densities. Radiative and absorptive properties are given to determine radiation from such gas mixtures. A computer code for calculating the axisymmetric channel flow of a gas mixture in chemical equilibrium, and laser energy absorption and convective and radiative heating is described. It is concluded that: (1) small amounts of cesium seed substantially increase the absorption coefficient of hydrogen; (2) cesium is a strong radiator and contributes greatly to radiation of cesium seeded hydrogen; (3) water vapor is a poor absorber; and (4) for 5.3mcm radiation, both H2O/CO and NO/CO seeded hydrogen mixtures are good absorbers.

Metabolic fate of poly-(lactic-co-glycolic acid)-based curcumin nanoparticles following oral administration.

PubMed

Harigae, Takahiro; Nakagawa, Kiyotaka; Miyazawa, Taiki; Inoue, Nao; Kimura, Fumiko; Ikeda, Ikuo; Miyazawa, Teruo

2016-01-01

Curcumin (CUR), the main polyphenol in turmeric, is poorly absorbed and rapidly metabolized following oral administration, which severely curtails its bioavailability. Poly-(lactic-co-glycolic acid)-based CUR nanoparticles (CUR-NP) have recently been suggested to improve CUR bioavailability, but this has not been fully verified. Specifically, no data are available about curcumin glucuronide (CURG), the major metabolite of CUR found in the plasma following oral administration of CUR-NP. Herein, we investigated the absorption and metabolism of CUR-NP and evaluated whether CUR-NP improves CUR bioavailability. Following oral administration of CUR-NP in rats, we analyzed the plasma and organ distribution of CUR and its metabolites using high-performance liquid chromatography-tandem mass spectrometry. To elucidate the mechanism of increased intestinal absorption of CUR-NP, we prepared mixed micelles comprised of phosphatidylcholine and bile salts and examined the micellar solubility of CUR-NP. Additionally, we investigated the cellular incorporation of the resultant micelles into differentiated Caco-2 human intestinal cells. Following in vivo administration of CUR-NP, CUR was effectively absorbed and present mainly as CURG in the plasma which contained significant amounts of the metabolite compared with other organs. Thus, CUR-NP increased intestinal absorption of CUR rather than decreasing metabolic degradation and conversion to other metabolites. In vitro, CUR encapsulated in CUR-NP was solubilized in mixed micelles; however, whether the micelles contained CUR or CUR-NP had little influence on cellular uptake efficiency. Therefore, we suggest that the high solubilization capacity of CUR-NP in mixed micelles, rather than cellular uptake efficiency, explains the high intestinal absorption of CUR-NP in vivo. These findings provide a better understanding of the bioavailability of CUR and CUR-NP following oral administration. To improve the bioavailability of CUR, future studies should focus on enhancing the resistance to metabolic degradation and conversion of CUR to other metabolites, which may lead to novel discoveries regarding food function and disease prevention.

Interpreting the structural and electrochemical complexity of 0.5Li{sub 2}MnO{sub 3}{lg_bullet}.0.5LiMO{sub 2} electrodes for lithium batteries (M=Mn{sub 0.5-x}Ni{sub 0.5-x}Co{sub 2x}, 0{le}x{le}0.5).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kang, S. H.; Kempgens, P.; Greenbaum, S.

2007-01-01

The structural and electrochemical features of layered 0.5Li{sub 2}MnO{sub 3} {center_dot} 0.5LiMO{sub 2} electrodes, in which M = Mn{sub 0.5-x}Ni{sub 0.5-x}Co{sub 2x} (0{le} x {le} 0.5), have been studied by powder X-ray diffraction, electrochemical differential-capacity measurements, {sup 7}Li magic-angle-spinning nuclear magnetic resonance, and X-ray absorption near-edge spectroscopy. Li{sub 2}MnO{sub 3}-like regions in the as-prepared samples were observed for all values of x, with transition-metal cation disorder between the LiMO{sub 2} and Li{sub 2}MnO{sub 3} components increasing with cobalt content (i.e., the value of x). The structural disorder and complexity of the electrochemical redox reactions increase when the Li{sub 2}MnO{sub 3}-likemore » regions within the electrode are activated to 4.6 V in lithium cells; interpretations of structural and electrochemical phenomena are provided.« less