Sample records for absorption spectrometer tdlas

  1. Thermal Boundary Layer Effects on Line-of-Sight Tunable Diode Laser Absorption Spectroscopy (TDLAS) Gas Concentration Measurements.

    PubMed

    Qu, Zhechao; Werhahn, Olav; Ebert, Volker

    2018-06-01

    The effects of thermal boundary layers on tunable diode laser absorption spectroscopy (TDLAS) measurement results must be quantified when using the line-of-sight (LOS) TDLAS under conditions with spatial temperature gradient. In this paper, a new methodology based on spectral simulation is presented quantifying the LOS TDLAS measurement deviation under conditions with thermal boundary layers. The effects of different temperature gradients and thermal boundary layer thickness on spectral collisional widths and gas concentration measurements are quantified. A CO 2 TDLAS spectrometer, which has two gas cells to generate the spatial temperature gradients, was employed to validate the simulation results. The measured deviations and LOS averaged collisional widths are in very good agreement with the simulated results for conditions with different temperature gradients. We demonstrate quantification of thermal boundary layers' thickness with proposed method by exploitation of the LOS averaged the collisional width of the path-integrated spectrum.

  2. Rapid, Time-Division Multiplexed, Direct Absorption- and Wavelength Modulation-Spectroscopy

    PubMed Central

    Klein, Alexander; Witzel, Oliver; Ebert, Volker

    2014-01-01

    We present a tunable diode laser spectrometer with a novel, rapid time multiplexed direct absorption- and wavelength modulation-spectroscopy operation mode. The new technique allows enhancing the precision and dynamic range of a tunable diode laser absorption spectrometer without sacrificing accuracy. The spectroscopic technique combines the benefits of absolute concentration measurements using calibration-free direct tunable diode laser absorption spectroscopy (dTDLAS) with the enhanced noise rejection of wavelength modulation spectroscopy (WMS). In this work we demonstrate for the first time a 125 Hz time division multiplexed (TDM-dTDLAS-WMS) spectroscopic scheme by alternating the modulation of a DFB-laser between a triangle-ramp (dTDLAS) and an additional 20 kHz sinusoidal modulation (WMS). The absolute concentration measurement via the dTDLAS-technique allows one to simultaneously calibrate the normalized 2f/1f-signal of the WMS-technique. A dTDLAS/WMS-spectrometer at 1.37 μm for H2O detection was built for experimental validation of the multiplexing scheme over a concentration range from 50 to 3000 ppmV (0.1 MPa, 293 K). A precision of 190 ppbV was achieved with an absorption length of 12.7 cm and an averaging time of two seconds. Our results show a five-fold improvement in precision over the entire concentration range and a significantly decreased averaging time of the spectrometer. PMID:25405508

  3. Field-rugged sensitive hydrogen peroxide sensor based on tunable diode laser absorption spectroscopy (TDLAS)

    NASA Astrophysics Data System (ADS)

    Frish, M. B.; Morency, J. R.; Laderer, M. C.; Wainner, R. T.; Parameswaran, K. R.; Kessler, W. J.; Druy, M. A.

    2010-04-01

    This paper reports the development and initial testing of a field-portable sensor for monitoring hydrogen peroxide (H2O2) and water (H2O) vapor concentrations during building decontamination after accidental or purposeful exposure to hazardous biological materials. During decontamination, a sterilization system fills ambient air with water and peroxide vapor to near-saturation. The peroxide concentration typically exceeds several hundred ppm for tens of minutes, and subsequently diminishes below 1 ppm. The H2O2/ H2O sensor is an adaptation of a portable gas-sensing platform based on Tunable Diode Laser Absorption Spectroscopy (TDLAS) technology. By capitalizing on its spectral resolution, the TDLAS analyzer isolates H2O2 and H2O spectral lines to measure both vapors using a single laser source. It offers a combination of sensitivity, specificity, fast response, dynamic range, linearity, ease of operation and calibration, ruggedness, and portability not available in alternative H2O2 detectors. The H2O2 range is approximately 0- 5,000 ppm. The autonomous and rugged instrument provides real-time data. It has been tested in a closed-loop liquid/vapor equilibrium apparatus and by comparison against electrochemical sensors.

  4. Simulate different environments TDLAS On the analysis of the test signal strength

    NASA Astrophysics Data System (ADS)

    Li, Xin; Zhou, Tao; Jia, Xiaodong

    2014-12-01

    TDLAS system is the use of the wavelength tuning characteristics of the laser diode, for detecting the absorption spectrum of the gas absorption line. Detecting the gas space, temperature, pressure and flow rate and concentration. The use of laboratory techniques TDLAS gas detection, experimental simulation engine combustion water vapor and smoke. using an optical lens system receives the signal acquisition and signal interference test analysis. Analog water vapor and smoke in two different environments in the sample pool interference. In both experiments environmental interference gas absorption in the optical signal acquisition, signal amplitude variation analysis, and records related to the signal data. In order to study site conditions in the engine combustion process for signal acquisition provides an ideal experimental data .

  5. Localization and Quantification of Trace-gas Fugitive Emissions Using a Portable Optical Spectrometer

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

    Zhang, Eric; Teng, Chu; van Kessel, Theodore

    We present a portable optical spectrometer for fugitive emissions monitoring of methane (CH4). The sensor operation is based on tunable diode laser absorption spectroscopy (TDLAS), using a 5 cm open path design, and targets the 2ν3 R(4) CH4 transition at 6057.1 cm-1 (1651 nm) to avoid cross-talk with common interfering atmospheric constituents. Sensitivity analysis indicates a normalized precision of 2.0 ppmv∙Hz-1/2, corresponding to a noise-equivalent absorption (NEA) of 4.4×10-6 Hz-1/2 and minimum detectible absorption (MDA) coefficient of αmin = 8.8×10-7 cm-1∙Hz-1/2. Our TDLAS sensor is deployed at the Methane Emissions Technology Evaluation Center (METEC) at Colorado State University (CSU) formore » initial demonstration of single-sensor based source localization and quantification of CH4 fugitive emissions. The TDLAS sensor is concurrently deployed with a customized chemi-resistive metal-oxide (MOX) sensor for accuracy benchmarking, demonstrating good visual correlation of the concentration time-series. Initial angle-of-arrival (AOA) results will be shown, and development towards source magnitude estimation will be described.« less

  6. Performance improvements in temperature reconstructions of 2-D tunable diode laser absorption spectroscopy (TDLAS)

    NASA Astrophysics Data System (ADS)

    Choi, Doo-Won; Jeon, Min-Gyu; Cho, Gyeong-Rae; Kamimoto, Takahiro; Deguchi, Yoshihiro; Doh, Deog-Hee

    2016-02-01

    Performance improvement was attained in data reconstructions of 2-dimensional tunable diode laser absorption spectroscopy (TDLAS). Multiplicative Algebraic Reconstruction Technique (MART) algorithm was adopted for data reconstruction. The data obtained in an experiment for the measurement of temperature and concentration fields of gas flows were used. The measurement theory is based upon the Beer-Lambert law, and the measurement system consists of a tunable laser, collimators, detectors, and an analyzer. Methane was used as a fuel for combustion with air in the Bunsen-type burner. The data used for the reconstruction are from the optical signals of 8-laser beams passed on a cross-section of the methane flame. The performances of MART algorithm in data reconstruction were validated and compared with those obtained by Algebraic Reconstruction Technique (ART) algorithm.

  7. HAI: A new TDLAS hygrometer for the HALO research aircraft

    NASA Astrophysics Data System (ADS)

    Klostermann, Tim; Afchine, Armin; Barthel, Jochen; Höh, Matthias; Wagner, Steven; Witzel, Oliver; Saathoff, Harald; Schiller, Cornelius; Ebert, Volker

    2010-05-01

    Water vapor is the most important greenhouse gas in the Earth's atmosphere and a key component for several physical and chemical processes. Therefore it is a key parameter to be measured during most research campaigns. The Hygrometer for Atmospheric Investigations (HAI) is especially designed for operations on the research aircraft HALO (High Altitude and LOng range research aircraft). HAI permits both, the in-situ measurement of water vapor with an open-path cell and the measurement of total water with an extractive close-path absorption cell. We are using TDLAS (Tunable Diode Laser Absorption Spectroscopy) in two water absorption bands with different line strength to increase the dynamical range. With this concept it is possible to measure from the middle troposphere up to the stratosphere. The open-path cell outside of the fuselage consists of a robust, aerodynamically designed aluminum structure with a single integrated White-cell for both laser beams. Although the mirror separation is only 15cm the cell allows an open absorption path of 4.8m. The detection of higher H2O concentrations is realized with a fiber coupled 1.4µm DFB diode laser. Inside the UTLS layer were small concentrations in the low ppm range are common, we employ up to 20 times stronger fundamental ro-vibration lines of the water molecule near 2.6µm. To supply this, the fiber coupled 2.6µm laser setup was developed and is a part of the HAI. Both detection wavelengths are introduced in the same open path cell via glass fibers which provide water measurements with a minimum of parasitic absorption. We will present the spectrometer design for high-quality airborne water measurements. Furthermore, first laboratory measurements will be shown.

  8. Flight-Ready TDLAS Combustion Sensor for the HIFiRE 2 Hypersonic Research Program

    DTIC Science & Technology

    2009-09-01

    Noise Sources 20 5.7 Total System Performance 21 6.0 ZOLO ARCHITECTURE 22 7.0 DESIGN DETAILS 23 7.1 Laser and Drive Electronics 23 7.2 Fiber Couplers...targets 8 2 Tunable Diode Laser Absorption Spectroscopy experiment 9 3 Light absorption by water vapor near 1393 nm 10 4a light transmission vs time 10...20 13 multimode fiber modal noise 21 14 TDLAS sensor architecture 22 15 sensor exploded view 23 16 sensor outline and mounting 23 17 laser power and

  9. Offsets in fiber-coupled diode laser hygrometers caused by parasitic absorption effects and their prevention

    NASA Astrophysics Data System (ADS)

    Buchholz, B.; Ebert, V.

    2014-07-01

    Large systematic errors in absorption spectrometers (AS) can be caused by ‘parasitic’ optical absorption (parA) outside the measurement region. In particular, calibration-free direct tunable diode laser AS (dTDLAS) can take advantage of an effective parA-compensation to provide correct absolute values. However, parA also negatively affects calibrated AS in calibration frequency and stability. A common strategy to suppress parA in TDLAS systems is to fiber-couple the light source and even the detector. However, this can be a critical approach if the TDL spectrometer is validated/calibrated under laboratory conditions in ambient humidity and used afterwards in much drier and variable conditions, for example in aircrafts. This paper shows that, e.g., ‘hermetically sealed’ butterfly packages, despite fiber coupling, can possess fixed as well as variable parA sections. Two new methods for absolute parA-quantification in dTDLAS were developed, including a novel, fiber-coupled, parA-free I0-detector for permanent parA-monitoring. Their dependences on ambient humidity/pressure and temporal behavior were studied. For the example of a 1.4 µm dTDLAS hygrometer SEALDH-II with a commercial DFB-laser module and an extractive 1.5 m path cell, we quantified the parA-induced signal offsets and their dependence on cell pressure. The conversion of parA-uncertainty into H2O signal uncertainty was studied and an updated uncertainty budget including parA-uncertainty was derived. The studies showed that parA in commercial laser modules can cause substantial, systematic concentration offsets of ≈25 ppmv fixed and ≈100 ppmv variable offsets for one meter absorption path. Applying our parA-quantification techniques these offsets could be compensated by a factor of 20 to an overall offset uncertainty of 4.5 ppmv m-1. Finally, we developed an innovative, integrated, µ-pumped closed-loop air drying unit for the parA minimization and temporal stabilization in airborne laser

  10. 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.

  11. Tomography for two-dimensional gas temperature distribution based on TDLAS

    NASA Astrophysics Data System (ADS)

    Luo, Can; Wang, Yunchu; Xing, Fei

    2018-03-01

    Based on tunable diode laser absorption spectroscopy (TDLAS), the tomography is used to reconstruct the combustion gas temperature distribution. The effects of number of rays, number of grids, and spacing of rays on the temperature reconstruction results for parallel ray are researched. The reconstruction quality is proportional to the ray number. The quality tends to be smoother when the ray number exceeds a certain value. The best quality is achieved when η is between 0.5 and 1. A virtual ray method combined with the reconstruction algorithms is tested. It is found that virtual ray method is effective to improve the accuracy of reconstruction results, compared with the original method. The linear interpolation method and cubic spline interpolation method, are used to improve the calculation accuracy of virtual ray absorption value. According to the calculation results, cubic spline interpolation is better. Moreover, the temperature distribution of a TBCC combustion chamber is used to validate those conclusions.

  12. Simultaneous measurement of 2-dimensional H2O concentration and temperature distribution in premixed methane/air flame using TDLAS-based tomography technology

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Wu, Qi; Huang, Qunxing; Zhang, Haidan; Yan, Jianhua; Cen, Kefa

    2015-07-01

    An innovative tomographic method using tunable diode laser absorption spectroscopy (TDLAS) and algebraic reconstruction technique (ART) is presented in this paper for detecting two-dimensional distribution of H2O concentration and temperature in a premixed flame. The collimated laser beam emitted from a low cost diode laser module was delicately split into 24 sub-beams passing through the flame from different angles and the acquired laser absorption signals were used to retrieve flame temperature and H2O concentration simultaneously. The efficiency of the proposed reconstruction system and the effect of measurement noise were numerically evaluated. The temperature and H2O concentration in flat methane/air premixed flames under three different equivalence ratios were experimentally measured and reconstruction results were compared with model calculations. Numerical assessments indicate that the TDLAS tomographic system is capable for temperature and H2O concentration profiles detecting even the noise strength reaches 3% of absorption signal. Experimental results under different combustion conditions are well demonstrated along the vertical direction and the distribution profiles are in good agreement with model calculation. The proposed method exhibits great potential for 2-D or 3-D combustion diagnostics including non-uniform flames.

  13. Toroidal Optical Microresonators as Single-Particle Absorption Spectrometers

    NASA Astrophysics Data System (ADS)

    Heylman, Kevin D.

    Single-particle and single-molecule measurements are invaluable tools for characterizing structural and energetic properties of molecules and nanomaterials. Photothermal microscopy in particular is an ultrasensitive technique capable of single-molecule resolution. In this thesis I introduce a new form of photothermal spectroscopy involving toroidal optical microresonators as detectors and a pair of non-interacting lasers as pump and probe for performing single-target absorption spectroscopy. The first three chapters will discuss the motivation, design principles, underlying theory, and fabrication process for the microresonator absorption spectrometer. With an early version of the spectrometer, I demonstrate photothermal mapping and all-optical tuning with toroids of different geometries in Chapter 4. In Chapter 5, I discuss photothermal mapping and measurement of the absolute absorption cross-sections of individual carbon nanotubes. For the next generation of measurements I incorporate all of the advances described in Chapter 2, including a double-modulation technique to improve detection limits and a tunable pump laser for spectral measurements on single gold nanoparticles. In Chapter 6 I observe sharp Fano resonances in the spectra of gold nanoparticles and describe them with a theoretical model. I continued to study this photonic-plasmonic hybrid system in Chapter 7 and explore the thermal tuning of the Fano resonance phase while quantifying the Fisher information. The new method of photothermal single-particle absorption spectroscopy that I will discuss in this thesis has reached record detection limits for microresonator sensing and is within striking distance of becoming the first single-molecule room-temperature absorption spectrometer.

  14. 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.

  15. 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.

  16. Product mass transfer resistance directly determined during freeze-drying cycle runs using tunable diode laser absorption spectroscopy (TDLAS) and pore diffusion model.

    PubMed

    Kuu, Wei Y; O'Bryan, Kevin R; Hardwick, Lisa M; Paul, Timothy W

    2011-08-01

    The pore diffusion model is used to express the dry layer mass transfer resistance, [Formula: see text], as a function of the ratio r(e)/?, where r(e) is the effective pore radius and ? is the tortuosity factor of the dry layer. Using this model, the effective pore radius of the dry layer can be estimated from the sublimation rate and product temperature profiles measured during primary drying. Freeze-drying cycle runs were performed using the LyoStar II dryer (FTS Systems), with real-time sublimation rate profiles during freeze drying continuously measured by tunable diode laser absorption spectroscopy (TDLAS). The formulations chosen for demonstration of the proposed approach include 5% mannitol, 5% sucrose, 5% lactose, 3% mannitol plus 2% sucrose, and a parenteral nutrition formulation denoted VitaM12. The three different methods used for determination of the product resistance are: (1) Using both the sublimation rate and product temperature profiles, (2) using the sublimation rate profile alone, and (3) using the product temperate profile alone. Unlike the second and third methods, the computation procedure of first method does not need solution of the complex heat and mass transfer equations.

  17. Note: A flexible light emitting diode-based broadband transient-absorption spectrometer

    NASA Astrophysics Data System (ADS)

    Gottlieb, Sean M.; Corley, Scott C.; Madsen, Dorte; Larsen, Delmar S.

    2012-05-01

    This Note presents a simple and flexible ns-to-ms transient absorption spectrometer based on pulsed light emitting diode (LED) technology that can be incorporated into existing ultrafast transient absorption spectrometers or operate as a stand-alone instrument with fixed-wavelength laser sources. The LED probe pulses from this instrument exhibit excellent stability (˜0.5%) and are capable of producing high signal-to-noise long-time (>100 ns) transient absorption signals either in a broadband multiplexed (spanning 250 nm) or in tunable narrowband (20 ns) operation. The utility of the instrument is demonstrated by measuring the photoinduced ns-to-ms photodynamics of the red/green absorbing fourth GMP phosphodiesterase/adenylyl cyclase/FhlA domain of the NpR6012 locus of the nitrogen-fixing cyanobacterium Nostoc punctiforme.

  18. Non-invasive product temperature determination during primary drying using tunable diode laser absorption spectroscopy.

    PubMed

    Schneid, Stefan C; Gieseler, Henning; Kessler, William J; Pikal, Michael J

    2009-09-01

    The goal of this work was to demonstrate the application of Tunable Diode Laser Absorption Spectroscopy (TDLAS) as a non-invasive method to determine the average product temperature of the batch during primary drying. The TDLAS sensor continuously measures the water vapor concentration and the vapor flow velocity in the spool connecting the freeze-dryer chamber and condenser. Vapor concentration and velocity data were then used to determine the average sublimation rate (g/s) which was subsequently integrated to evaluate the amount of water removed from the product. Position dependent vial heat transfer coefficients (K(v)) were evaluated using the TDLAS sensor data for 20 mL vials during sublimation tests with pure water. TDLAS K(v) data showed good agreement to K(v) data obtained by the traditional gravimetric procedure. K(v) for edge vials was found to be about 20-30% higher than that of center vials. A weighted K(v) was then used to predict a representative average product temperature from TDLAS data in partial and full load freeze drying runs with 5%, 7.5%, or 10% (w/w) sucrose, mannitol, and glycine solutions. TDLAS product temperatures for all freeze-drying runs were within 1-2 degrees C of "center vial" steady state thermocouple data.

  19. Space Launch System Base Heating Test: Tunable Diode Laser Absorption Spectroscopy

    NASA Technical Reports Server (NTRS)

    Parker, Ron; Carr, Zak; MacLean, Matthew; Dufrene, Aaron; Mehta, Manish

    2016-01-01

    This paper describes the Tunable Diode Laser Absorption Spectroscopy (TDLAS) measurement of several water transitions that were interrogated during a hot-fire testing of the Space Launch Systems (SLS) sub-scale vehicle installed in LENS II. The temperature of the recirculating gas flow over the base plate was found to increase with altitude and is consistent with CFD results. It was also observed that the gas above the base plate has significant velocity along the optical path of the sensor at the higher altitudes. The line-by-line analysis of the H2O absorption features must include the effects of the Doppler shift phenomena particularly at high altitude. The TDLAS experimental measurements and the analysis procedure which incorporates the velocity dependent flow will be described.

  20. Scanning imaging absorption spectrometer for atmospheric chartography

    NASA Technical Reports Server (NTRS)

    Burrows, John P.; Chance, Kelly V.

    1991-01-01

    The SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY is an instrument which measures backscattered, reflected, and transmitted light from the earth's atmosphere and surface. SCIAMACHY has eight spectral channels which observe simultaneously the spectral region between 240 and 1700 nm and selected windows between 1940 and 2400 nm. Each spectral channel contains a grating and linear diode array detector. SCIAMACHY observes the atmosphere in nadir, limb, and solar and lunar occultation viewing geometries.

  1. [Signal analysis and spectrum distortion correction for tunable diode laser absorption spectroscopy system].

    PubMed

    Bao, Wei-Yi; Zhu, Yong; Chen, Jun; Chen, Jun-Qing; Liang, Bo

    2011-04-01

    In the present paper, the signal of a tunable diode laser absorption spectroscopy (TDLAS) trace gas sensing system, which has a wavelength modulation with a wide range of modulation amplitudes, is studied based on Fourier analysis method. Theory explanation of spectrum distortion induced by laser intensity amplitude modulation is given. In order to rectify the spectrum distortion, a method of synchronous amplitude modulation suppression by a variable optical attenuator is proposed. To validate the method, an experimental setup is designed. Absorption spectrum measurement experiments on CO2 gas were carried out. The results show that the residual laser intensity modulation amplitude of the experimental system is reduced to -0.1% of its original value and the spectrum distortion improvement is 92% with the synchronous amplitude modulation suppression. The modulation amplitude of laser intensity can be effectively reduced and the spectrum distortion can be well corrected by using the given correction method and system. By using a variable optical attenuator in the TDLAS (tunable diode laser absorption spectroscopy) system, the dynamic range requirements of photoelectric detector, digital to analog converter, filters and other aspects of the TDLAS system are reduced. This spectrum distortion correction method can be used for online trace gas analyzing in process industry.

  2. HAI, a new airborne, absolute, twin dual-channel, multi-phase TDLAS-hygrometer: background, design, setup, and first flight data

    NASA Astrophysics Data System (ADS)

    Buchholz, Bernhard; Afchine, Armin; Klein, Alexander; Schiller, Cornelius; Krämer, Martina; Ebert, Volker

    2017-01-01

    The novel Hygrometer for Atmospheric Investigation (HAI) realizes a unique concept for simultaneous gas-phase and total (gas-phase + evaporated cloud particles) water measurements. It has been developed and successfully deployed for the first time on the German HALO research aircraft. This new instrument combines direct tunable diode laser absorption spectroscopy (dTDLAS) with a first-principle evaluation method to allow absolute water vapor measurements without any initial or repetitive sensor calibration using a reference gas or a reference humidity generator. HAI contains two completely independent dual-channel (closed-path, open-path) spectrometers, one at 1.4 and one at 2.6 µm, which together allow us to cover the entire atmospheric H2O range from 1 to 40 000 ppmv with a single instrument. Both spectrometers each comprise a separate, wavelength-individual extractive, closed-path cell for total water (ice and gas-phase) measurements. Additionally, both spectrometers couple light into a common open-path cell outside of the aircraft fuselage for a direct, sampling-free, and contactless determination of the gas-phase water content. This novel twin dual-channel setup allows for the first time multiple self-validation functions, in particular a reliable, direct, in-flight validation of the open-path channels. During the first field campaigns, the in-flight deviations between the independent and calibration-free channels (i.e., closed-path to closed-path and open-path to closed-path) were on average in the 2 % range. Further, the fully autonomous HAI hygrometer allows measurements up to 240 Hz with a minimal integration time of 1.4 ms. The best precision is achieved by the 1.4 µm closed-path cell at 3.8 Hz (0.18 ppmv) and by the 2.6 µm closed-path cell at 13 Hz (0.055 ppmv). The requirements, design, operation principle, and first in-flight performance of the hygrometer are described and discussed in this work.

  3. Compact TDLAS based sensor design using interband cascade lasers for mid-IR trace gas sensing

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

    Dong, Lei; Tittel, Frank K.; Li, Chunguang

    2016-02-25

    Two compact TDLAS sensor systems based on different structural optical cores were developed. The two optical cores combine two recent developments, gallium antimonide (GaSb)-based ICL and a compact multipass gas cell (MPGC) with the goal to create compact TDLAS based sensors for the mid-IR gas detection with high detection sensitivity and low power consumption. The sensors achieved minimum detection limits of ~5 ppbv and ~8 ppbv, respectively, for CH 4 and C 2H 6 concentration measurements with a 3.7-W power consumption.

  4. Laser Absorption spectrometer instrument for tomographic 2D-measurement of climate gas emission from soils

    NASA Astrophysics Data System (ADS)

    Seidel, Anne; Wagner, Steven; Dreizler, Andreas; Ebert, Volker

    2014-05-01

    One of the most intricate effects in climate modelling is the role of permafrost thawing during the global warming process. Soil that has formerly never totally lost its ice cover now emits climate gases due to melting processes[1]. For a better prediction of climate development and possible feedback mechanisms, insights into physical procedures (like e.g. gas emission from underground reservoirs) are required[2]. Therefore, a long-term quantification of greenhouse gas concentrations (and further on fluxes) is necessary and the related structures that are responsible for emission need to be identified. In particular the spatial heterogeneity of soils caused by soil internal structures (e.g. soil composition changes or surface cracks) or by surface modifications (e.g. by plant growth) generate considerable complexities and difficulties for local measurements, for example with soil chambers. For such situations, which often cannot be avoided, a spatially resolved 2D-measurement to identify and quantify the gas emission from the structured soil would be needed, to better understand the influence of the soil sub-structures on the emission behavior. Thus we designed a spatially scanning laser absorption spectrometer setup to determine a 2D-gas concentration map in the soil-air boundary layer. The setup is designed to cover the surfaces in the range of square meters in a horizontal plane above the soil to be investigated. Existing field instruments for gas concentration or flux measurements are based on point-wise measurements, so structure identification is very tedious or even impossible. For this reason, we have developed a tomographic in-situ instrument based on TDLAS ('tunable diode laser absorption spectroscopy') that delivers absolute gas concentration distributions of areas with 0.8m × 0.8m size, without any need for reference measurements with a calibration gas. It is a simple and robust device based on a combination of scanning mirrors and reflecting foils, so

  5. 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.

  6. 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.

  7. Five-Channel Infrared Laser Absorption Spectrometer for Combustion Product Monitoring Aboard Manned Spacecraft

    NASA Technical Reports Server (NTRS)

    Briggs, Ryan M.; Frez, Clifford; Borgentun, Carl E.; Bagheri, Mahmood; Forouhar, Siamak; May, Randy D.

    2014-01-01

    Continuous combustion product monitoring aboard manned spacecraft can prevent chronic exposure to hazardous compounds and also provides early detection of combustion events. As future missions extend beyond low-Earth orbit, analysis of returned environmental samples becomes impractical and safety monitoring should be performed in situ. Here, we describe initial designs of a five-channel tunable laser absorption spectrometer to continuously monitor combustion products with the goal of minimal maintenance and calibration over long-duration missions. The instrument incorporates dedicated laser channels to simultaneously target strong mid-infrared absorption lines of CO, HCl, HCN, HF, and CO2. The availability of low-power-consumption semiconductor lasers operating in the 2 to 5 micron wavelength range affords the flexibility to select absorption lines for each gas with maximum interaction strength and minimal interference from other gases, which enables the design of a compact and mechanically robust spectrometer with low-level sensitivity. In this paper, we focus primarily on absorption line selection based on the availability of low-power single-mode semiconductor laser sources designed specifically for the target wavelength range.

  8. 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.

  9. Application of tunable diode laser absorption spectroscopy in the detection of oxygen

    NASA Astrophysics Data System (ADS)

    Zhou, Xin; Jin, Xing

    2015-10-01

    Most aircrafts is driven by chemic energy which is released in the combustion process. For improving the capability of engine and controlling the running on-time, the processes of fuel physics and chemistry need to be analysis by kinds of high quality sensor. In the research of designing and improving the processes of fuel physics and chemistry, the concentration, temperature and velocity of kinds of gas in the combustor need to be detected and measured. In addition, these engines and research equipments are always in the harsh environment of high temperature, high pressure and high speed. The harsh environment needs the sensor to be high reliability, well repetition, no cross- sensitivity between gases, and the traditional measurement system can't satisfy the metrical requirement well. Tunable diode laser absorption spectroscopy (TDLAS) analytic measurement technology can well satisfy the measurement in the harsh environment, which can support the whole measurement plan and high quality measurement system. Because the TDLAS sensor has the excellence of small bulk, light weight, high reliability and well specifically measurement, the TDLAS measurement technology has wide prospects. Different from most measurements, only a beam of laser can be pass through the measured environment by TDLAS, and the measurement equipment needn't be set in the harsh environment. So, the TDLAS equipment can't be interrupted by the measured equipment. The ability of subsistence in the harsh environment is very valuable, especially in the measurement on the subject of aerospace with environment of high speed, combustion and plasma. This paper focuses on the collecting the articles on the subject of oxygen detection of TDLAS. By analyzing the research and results of the articles, we conclude the central issues, difficulties and results. And we can get some instructive conclusions.

  10. Rapid freeze-drying cycle optimization using computer programs developed based on heat and mass transfer models and facilitated by tunable diode laser absorption spectroscopy (TDLAS).

    PubMed

    Kuu, Wei Y; Nail, Steven L

    2009-09-01

    Computer programs in FORTRAN were developed to rapidly determine the optimal shelf temperature, T(f), and chamber pressure, P(c), to achieve the shortest primary drying time. The constraint for the optimization is to ensure that the product temperature profile, T(b), is below the target temperature, T(target). Five percent mannitol was chosen as the model formulation. After obtaining the optimal sets of T(f) and P(c), each cycle was assigned with a cycle rank number in terms of the length of drying time. Further optimization was achieved by dividing the drying time into a series of ramping steps for T(f), in a cascading manner (termed the cascading T(f) cycle), to further shorten the cycle time. For the purpose of demonstrating the validity of the optimized T(f) and P(c), four cycles with different predicted lengths of drying time, along with the cascading T(f) cycle, were chosen for experimental cycle runs. Tunable diode laser absorption spectroscopy (TDLAS) was used to continuously measure the sublimation rate. As predicted, maximum product temperatures were controlled slightly below the target temperature of -25 degrees C, and the cascading T(f)-ramping cycle is the most efficient cycle design. In addition, the experimental cycle rank order closely matches with that determined by modeling.

  11. Scanning, standoff TDLAS leak imaging and quantification

    NASA Astrophysics Data System (ADS)

    Wainner, Richard T.; Aubut, Nicholas F.; Laderer, Matthew C.; Frish, Michael B.

    2017-05-01

    This paper reports a novel quantitative gas plume imaging tool, based on active near-infrared Backscatter Tunable Diode Laser Absorption Spectroscopy (b-TDLAS) technology, designed for upstream natural gas leak applications. The new tool integrates low-cost laser sensors with video cameras to create a highly sensitive gas plume imager that also quantifies emission rate, all in a lightweight handheld ergonomic package. It is intended to serve as a lower-cost, higherperformance, enhanced functionality replacement for traditional passive non-quantitative mid-infrared Optical Gas Imagers (OGI) which are utilized by industry to comply with natural gas infrastructure Leak Detection and Repair (LDAR) requirements. It addresses the need for reliable, robust, low-cost sensors to detect and image methane leaks, and to quantify leak emission rates, focusing on inspections of upstream oil and gas operations, such as well pads, compressors, and gas plants. It provides: 1) Colorized quantified images of path-integrated methane concentration. The images depict methane plumes (otherwise invisible to the eye) actively interrogated by the laser beam overlaid on a visible camera image of the background. The detection sensitivity exceeds passive OGI, thus simplifying the manual task of leak detection and location; and 2) Data and algorithms for using the quantitative information gathered by the active detection technique to deduce plume flux (i.e. methane emission rate). This key capability will enable operators to prioritize leak repairs and thereby minimize the value of lost product, as well as to quantify and minimize greenhouse gas emissions, using a tool that meets EPA LDAR imaging equipment requirements.

  12. Combined "dual" absorption and fluorescence smartphone spectrometers.

    PubMed

    Arafat Hossain, Md; Canning, John; Ast, Sandra; Cook, Kevin; Rutledge, Peter J; Jamalipour, Abbas

    2015-04-15

    A combined "dual" absorption and fluorescence smartphone spectrometer is demonstrated. The optical sources used in the system are the white flash LED of the smartphone and an orthogonally positioned and interchangeable UV (λex=370  nm) and blue (λex=450  nm) LED. The dispersive element is a low-cost, nano-imprinted diffraction grating coated with Au. Detection over a 300 nm span with 0.42 nm/pixel resolution was carried out with the camera CMOS chip. By integrating the blue and UV excitation sources into the white LED circuitry, the entire system is self-contained within a 3D printed case and powered from the smartphone battery; the design can be scaled to add further excitation sources. Using a customized app, acquisition of absorption and fluorescence spectra are demonstrated using a blue-absorbing and green-emitting pH-sensitive amino-naphthalimide-based fluorescent probe and a UV-absorbing and blue-emitting Zn2+-sensitive fluoro-ionophore.

  13. Efficiency of the High Efficiency Total Absorption Spectrometer (HECTOR)

    NASA Astrophysics Data System (ADS)

    Sprowal, Zaire; Simon, Anna; Reingold, Craig; Spyrou, Artemis; Naqvi, Farheen; Dombos, Alexander; Palmisano, Alicia; Anderson, Tyler; Anderson, Samuel; Moylan, Shane; Seymour, Christopher; Skulski, Michael; Smith, Mallory K.; Strauss, Sabrina; Kolk, Byant Vande

    2016-09-01

    The p-process is a nucleosynthesis process that occurs in explosive environments such as type II and Ia supernovae and is responsible for production of heavy proton rich nuclei. Gamma rays emitted during these explosions induce several photo-disintegration reactions: (γ,n), (γ,p), and (γ , α). To study these interactions, the inverse of these reactions are measured experimentally. The High Efficiency TOtal absorption spectrometeR (HECTOR) at the University of Notre Dame was built for measuring these reactions. Standard gamma sources 60Co and 137Cs and known resonances in 27Al(p, γ)28Si reaction were used to experimentally determine HECTOR's summing efficiency. Here, the preliminary analysis will be presented and the results will be compared to the Geant4 simulation of the array. This work was supported by the National Science Foundation under the Grant Number PHYS-1614442.

  14. Reconstruction of combustion temperature and gas concentration distributions using line-of-sight tunable diode laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Zhirong; Sun, Pengshuai; Pang, Tao; Xia, Hua; Cui, Xiaojuan; Li, Zhe; Han, Luo; Wu, Bian; Wang, Yu; Sigrist, Markus W.; Dong, Fengzhong

    2016-07-01

    Spatial temperature and gas concentration distributions are crucial for combustion studies to characterize the combustion position and to evaluate the combustion regime and the released heat quantity. Optical computer tomography (CT) enables the reconstruction of temperature and gas concentration fields in a flame on the basis of line-of-sight tunable diode laser absorption spectroscopy (LOS-TDLAS). A pair of H2O absorption lines at wavelengths 1395.51 and 1395.69 nm is selected. Temperature and H2O concentration distributions for a flat flame furnace are calculated by superimposing two absorption peaks with a discrete algebraic iterative algorithm and a mathematical fitting algorithm. By comparison, direct absorption spectroscopy measurements agree well with the thermocouple measurements and yield a good correlation. The CT reconstruction data of different air-to-fuel ratio combustion conditions (incomplete combustion and full combustion) and three different types of burners (one, two, and three flat flame furnaces) demonstrate that TDLAS has the potential of short response time and enables real-time temperature and gas concentration distribution measurements for combustion diagnosis.

  15. Wavelength calibration of imaging spectrometer using atmospheric absorption features

    NASA Astrophysics Data System (ADS)

    Zhou, Jiankang; Chen, Yuheng; Chen, Xinhua; Ji, Yiqun; Shen, Weimin

    2012-11-01

    Imaging spectrometer is a promising remote sensing instrument widely used in many filed, such as hazard forecasting, environmental monitoring and so on. The reliability of the spectral data is the determination to the scientific communities. The wavelength position at the focal plane of the imaging spectrometer will change as the pressure and temperature vary, or the mechanical vibration. It is difficult for the onboard calibration instrument itself to keep the spectrum reference accuracy and it also occupies weight and the volume of the remote sensing platform. Because the spectral images suffer from the atmospheric effects, the carbon oxide, water vapor, oxygen and solar Fraunhofer line, the onboard wavelength calibration can be processed by the spectral images themselves. In this paper, wavelength calibration is based on the modeled and measured atmospheric absorption spectra. The modeled spectra constructed by the atmospheric radiative transfer code. The spectral angle is used to determine the best spectral similarity between the modeled spectra and measured spectra and estimates the wavelength position. The smile shape can be obtained when the matching process across all columns of the data. The present method is successful applied on the Hyperion data. The value of the wavelength shift is obtained by shape matching of oxygen absorption feature and the characteristics are comparable to that of the prelaunch measurements.

  16. Measurement of glyoxal using an incoherent broadband cavity enhanced absorption spectrometer

    NASA Astrophysics Data System (ADS)

    Washenfelder, R. A.; Langford, A. O.; Fuchs, H.; Brown, S. S.

    2008-08-01

    We describe an instrument for simultaneous measurements of glyoxal (CHOCHO) and nitrogen dioxide (NO2) using cavity enhanced absorption spectroscopy with a broadband light source. The output of a Xenon arc lamp is coupled into a 1 m optical cavity, and the spectrum of light exiting the cavity is recorded by a grating spectrometer with a charge-coupled device (CCD) array detector. The mirror reflectivity and effective path lengths are determined from the known Rayleigh scattering of He and dry zero air (N2+O2). Least-squares fitting, using published reference spectra, allow the simultaneous retrieval of CHOCHO, NO2, O4, and H2O in the 441 to 469 nm spectral range. For a 1-min sampling time, the minimum detectable absorption is 4×10-10 cm-1, and the precision (±1σ) on signal for measurements of CHOCHO and NO2 is 29 pptv and 20 pptv, respectively. We directly compare the incoherent broadband cavity enhanced absorption spectrometer to 404 and 532 nm cavity ringdown instruments for CHOCHO and NO2 detection, and find linear agreement over a wide range of concentrations. The instrument has been tested in the laboratory with both synthetic and real air samples, and the demonstrated sensitivity and specificity suggest a strong potential for field measurements of both CHOCHO and NO2.

  17. Capillary absorption spectrometer and process for isotopic analysis of small samples

    DOEpatents

    Alexander, M. Lizabeth; Kelly, James F.; Sams, Robert L.; Moran, James J.; Newburn, Matthew K.; Blake, Thomas A.

    2016-03-29

    A capillary absorption spectrometer and process are described that provide highly sensitive and accurate stable absorption measurements of analytes in a sample gas that may include isotopologues of carbon and oxygen obtained from gas and biological samples. It further provides isotopic images of microbial communities that allow tracking of nutrients at the single cell level. It further targets naturally occurring variations in carbon and oxygen isotopes that avoids need for expensive isotopically labeled mixtures which allows study of samples taken from the field without modification. The method also permits sampling in vivo permitting real-time ambient studies of microbial communities.

  18. Capillary absorption spectrometer and process for isotopic analysis of small samples

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

    Alexander, M. Lizabeth; Kelly, James F.; Sams, Robert L.

    A capillary absorption spectrometer and process are described that provide highly sensitive and accurate stable absorption measurements of analytes in a sample gas that may include isotopologues of carbon and oxygen obtained from gas and biological samples. It further provides isotopic images of microbial communities that allow tracking of nutrients at the single cell level. It further targets naturally occurring variations in carbon and oxygen isotopes that avoids need for expensive isotopically labeled mixtures which allows study of samples taken from the field without modification. The process also permits sampling in vivo permitting real-time ambient studies of microbial communities.

  19. A Fourier transform spectrometer for visible and near ultra-violet measurements of atmospheric absorption

    NASA Technical Reports Server (NTRS)

    Parsons, C. L.; Gerlach, J. C.; Whitehurst, M.

    1982-01-01

    The development of a prototype, ground-based, Sun-pointed Michelson interferometric spectrometer is described. Its intended use is to measure the atmospheric amount of various gases which absorb in the near-infrared, visible, and near-ultraviolet portions of the electromagnetic spectrum. Preliminary spectra which contain the alpha, 0.8 micrometer, and rho sigma tau water vapor absorption bands in the near-infrared are presented to indicate the present capability of the system. Ultimately, the spectrometer can be used to explore the feasible applications of Fourier transform spectroscopy in the ultraviolet where grating spectrometers were used exclusively.

  20. Determination of exhaled nitric oxide distributions in a diverse sample population using tunable diode laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Namjou, K.; Roller, C. B.; Reich, T. E.; Jeffers, J. D.; McMillen, G. L.; McCann, P. J.; Camp, M. A.

    2006-11-01

    A liquid-nitrogen free mid-infrared tunable diode laser absorption spectroscopy (TDLAS) system equipped with a folded-optical-path astigmatic Herriott cell was used to measure levels of exhaled nitric oxide (eNO) and exhaled carbon dioxide (eCO2) in breath. Quantification of absolute eNO concentrations was performed using NO/CO2 absorption ratios measured by the TDLAS system coupled with absolute eCO2 concentrations measured with a non-dispersive infrared sensor. This technique eliminated the need for routine calibrations using standard cylinder gases. The TDLAS system was used to measure eNO in children and adults (n=799, ages 5 to 64) over a period of more than one year as part of a field study. Volunteers for the study self-reported data including age, height, weight, and health status. The resulting data were used to assess system performance and to generate eNO and eCO2 distributions, which were found to be log-normal and Gaussian, respectively. There were statistically significant differences in mean eNO levels for males and females as well as for healthy and steroid naïve asthmatic volunteers not taking corticosteroid therapies. Ambient NO levels affected measured eNO concentrations only slightly, but this effect was not statistically significant.

  1. The differential absorption hard x-ray spectrometer at the Z facility

    DOE PAGES

    Bell, Kate S.; Coverdale, Christine A.; Ampleford, David J.; ...

    2017-08-03

    The Differential Absorption Hard X-ray (DAHX) spectrometer is a diagnostic developed to measure time-resolved radiation between 60 keV and 2 MeV at the Z Facility. It consists of an array of 7 Si PIN diodes in a tungsten housing that provides collimation and coarse spectral resolution through differential filters. DAHX is a revitalization of the Hard X-Ray Spectrometer (HXRS) that was fielded on Z prior to refurbishment in 2006. DAHX has been tailored to the present radiation environment in Z to provide information on the power, spectral shape, and time profile of the hard emission by plasma radiation sources drivenmore » by the Z Machine.« less

  2. Trace gas absorption spectroscopy using laser difference-frequency spectrometer for environmental application

    NASA Technical Reports Server (NTRS)

    Chen, W.; Cazier, F.; Boucher, D.; Tittel, F. K.; Davies, P. B.

    2001-01-01

    A widely tunable infrared spectrometer based on difference frequency generation (DFG) has been developed for organic trace gas detection by laser absorption spectroscopy. On-line measurements of concentration of various hydrocarbons, such as acetylene, benzene, and ethylene, were investigated using high-resolution DFG trace gas spectroscopy for highly sensitive detection.

  3. Portable 4.6 Micrometers Laser Absorption Spectrometer for Carbon Monoxide Monitoring and Fire Detection

    NASA Technical Reports Server (NTRS)

    Briggs, Ryan M.; Frez, Clifford; Forouhar, Siamak; May, Randy D.; Ruff, Gary A.

    2013-01-01

    The air quality aboard manned spacecraft must be continuously monitored to ensure crew safety and identify equipment malfunctions. In particular, accurate real-time monitoring of carbon monoxide (CO) levels helps to prevent chronic exposure and can also provide early detection of combustion-related hazards. For long-duration missions, environmental monitoring grows in importance, but the mass and volume of monitoring instruments must be minimized. Furthermore, environmental analysis beyond low-Earth orbit must be performed in-situ, as sample return becomes impractical. Due to their small size, low power draw, and performance reliability, semiconductor-laser-based absorption spectrometers are viable candidates for this purpose. To reduce instrument form factor and complexity, the emission wavelength of the laser source should coincide with strong fundamental absorption lines of the target gases, which occur in the 3 to 5 micrometers wavelength range for most combustion products of interest, thereby reducing the absorption path length required for low-level concentration measurements. To address the needs of current and future NASA missions, we have developed a prototype absorption spectrometer using a semiconductor quantum cascade laser source operating near 4.6 micrometers that can be used to detect low concentrations of CO with a compact single-pass absorption cell. In this study, we present the design of the prototype instrument and report on measurements of CO emissions from the combustion of a variety of aerospace plastics.

  4. Airborne Carbon Dioxide Laser Absorption Spectrometer for IPDA Measurements of Tropospheric CO2: Recent Results

    NASA Technical Reports Server (NTRS)

    Spiers, Gary D.; Menzies, Robert T.

    2008-01-01

    The National Research Council's decadal survey on Earth Science and Applications from Space[1] recommended the Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission for launch in 2013-2016 as a logical follow-on to the Orbiting Carbon Observatory (OCO) which is scheduled for launch in late 2008 [2]. The use of a laser absorption measurement technique provides the required ability to make day and night measurements of CO2 over all latitudes and seasons. As a demonstrator for an approach to meeting the instrument needs for the ASCENDS mission we have developed the airborne Carbon Dioxide Laser Absorption Spectrometer (CO2LAS) which uses the Integrated Path Differential Absorption (IPDA) Spectrometer [3] technique operating in the 2 micron wavelength region.. During 2006 a short engineering checkout flight of the CO2LAS was conducted and the results presented previously [4]. Several short flight campaigns were conducted during 2007 and we report results from these campaigns.

  5. Rapid determination of vial heat transfer parameters using tunable diode laser absorption spectroscopy (TDLAS) in response to step-changes in pressure set-point during freeze-drying.

    PubMed

    Kuu, Wei Y; Nail, Steven L; Sacha, Gregory

    2009-03-01

    The purpose of this study was to perform a rapid determination of vial heat transfer parameters, that is, the contact parameter K(cs) and the separation distance l(v), using the sublimation rate profiles measured by tunable diode laser absorption spectroscopy (TDLAS). In this study, each size of vial was filled with pure water followed by a freeze-drying cycle using a LyoStar II dryer (FTS Systems) with step-changes of the chamber pressure set-point at to 25, 50, 100, 200, 300, and 400 mTorr. K(cs) was independently determined by nonlinear parameter estimation using the sublimation rates measured at the pressure set-point of 25 mTorr. After obtaining K(cs), the l(v) value for each vial size was determined by nonlinear parameter estimation using the pooled sublimation rate profiles obtained at 25 to 400 mTorr. The vial heat transfer coefficient K(v), as a function of the chamber pressure, was readily calculated, using the obtained K(cs) and l(v) values. It is interesting to note the significant difference in K(v) of two similar types of 10 mL Schott tubing vials, primary due to the geometry of the vial-bottom, as demonstrated by the images of the contact areas of the vial-bottom. (c) 2008 Wiley-Liss, Inc. and the American Pharmacists Association

  6. A novel multiplex absorption spectrometer for time-resolved studies

    NASA Astrophysics Data System (ADS)

    Lewis, Thomas; Heard, Dwayne E.; Blitz, Mark A.

    2018-02-01

    A Time-Resolved Ultraviolet/Visible (UV/Vis) Absorption Spectrometer (TRUVAS) has been developed that can simultaneously monitor absorption at all wavelengths between 200 and 800 nm with millisecond time resolution. A pulsed photolysis laser (KrF 248 nm) is used to initiate chemical reactions that create the target species. The absorption signals from these species evolve as the composition of the gas in the photolysis region changes over time. The instrument can operate at pressures over the range ˜10-800 Torr and can measure time-resolved absorbances <10-4 in the UV (300 nm) and even lower in the visible (580 nm) 2.3 × 10-5, with the peak of sensitivity at ˜500 nm. The novelty of this setup lies in the arrangement of the multipass optics. Although appearing similar to other multipass optical systems (in particular the Herriott cell), there are fundamental differences, most notably the ability to adjust each mirror to maximise the overlap between the probe beam and the photolysis laser. Another feature which aids the sensitivity and versatility of the system is the use of 2 high-throughput spectrographs coupled with sensitive line-array CCDs, which can measure absorbance from ˜200 to 800 nm simultaneously. The capability of the instrument is demonstrated via measurements of the absorption spectrum of the peroxy radical, HOCH2CH2O2, and its self-reaction kinetics.

  7. Evaluation of tunable diode laser absorption spectroscopy for in-process water vapor mass flux measurements during freeze drying.

    PubMed

    Gieseler, Henning; Kessler, William J; Finson, Michael; Davis, Steven J; Mulhall, Phillip A; Bons, Vincent; Debo, David J; Pikal, Michael J

    2007-07-01

    The goal of this work was to demonstrate the use of Tunable Diode Laser Absorption Spectroscopy (TDLAS) as a noninvasive method to continuously measure the water vapor concentration and the vapor flow velocity in the spool connecting a freeze-dryer chamber and condenser. The instantaneous measurements were used to determine the water vapor mass flow rate (g/s). The mass flow determinations provided a continuous measurement of the total amount of water removed. Full load runs of pure water at different pressure and shelf temperature settings and a 5% (w/w) mannitol product run were performed in both laboratory and pilot scale freeze dryers. The ratio of "gravimetric/TDLAS" measurements of water removed was 1.02 +/- 0.06. A theoretical heat transfer model was used to predict the mass flow rate and the model results were compared to both the gravimetric and TDLAS data. Good agreement was also observed in the "gravimetric/TDLAS" ratio for the 5% mannitol runs dried in both freeze dryers. The endpoints of primary and secondary drying for the product runs were clearly identified. Comparison of the velocity and mass flux profiles between the laboratory and pilot dryers indicated a higher restriction to mass flow for the lab scale freeze dryer. Copyright 2007 Wiley-Liss, Inc.

  8. The laser absorption spectrometer - A new remote sensing instrument for atmospheric pollution monitoring

    NASA Technical Reports Server (NTRS)

    Shumate, M. S.

    1974-01-01

    An instrument capable of remotely monitoring trace atmospheric constituents is described. The instrument, called a laser absorption spectrometer, can be operated from an aircraft or spacecraft to measure the concentration of selected gases in three dimensions. This device will be particularly useful for rapid determination of pollutant levels in urban areas.

  9. Absorption spectra of localized surface plasmon resonance observed in an inline/picoliter spectrometer cell fabricated by a near ultraviolet femtosecond laser

    NASA Astrophysics Data System (ADS)

    Shiraishi, Masahiko; Nishiyama, Michiko; Watanabe, Kazuhiro; Kubodera, Shoichi

    2018-03-01

    Absorption spectra based on localized surface plasmon resonance (LSPR) were obtained with an inline/picoliter spectrometer cell. The spectrometer cell was fabricated into an optical glass fiber by focusing a near UV (NUV) femtosecond laser pulses at a wavelength of 400 nm with an energy of 30 μJ. The laser beam was focused from two directions opposite to each other to fabricate a through-hole spectrometer cell. A diameter of the cell was approximately 3 μm, and the length was approximately 62.5 μm, which was nearly equal to the core diameter of the optical fiber. Liquid solution of gold nanoparticles (GNPs) with a diameter of 5-10 nm was injected into the spectrometer cell with its volume of 0.4 pL. The absorption peak centered at 518 nm was observed. An increase of absorption associated with the increase of the number of nanoparticles was in agreement with the numerical calculation based on the Lambert-Beer law.

  10. Measurement of glyoxal using an incoherent broadband cavity enhanced absorption spectrometer

    NASA Astrophysics Data System (ADS)

    Washenfelder, R. A.; Langford, A. O.; Fuchs, H.; Brown, S. S.

    2008-12-01

    We describe an instrument for simultaneous measurements of glyoxal (CHOCHO) and nitrogen dioxide (NO2) using cavity enhanced absorption spectroscopy with a broadband light source. The output of a Xenon arc lamp is coupled into a 1 m optical cavity, and the spectrum of light exiting the cavity is recorded by a grating spectrometer with a charge-coupled device (CCD) array detector. The mirror reflectivity and effective path lengths are determined from the known Rayleigh scattering of He and dry zero air (N2+O2). Least-squares fitting, using published reference spectra, allow the simultaneous retrieval of CHOCHO, NO2, O4, and H2O in the 441 to 469 nm spectral range. For a 1-min sampling time, the precision (±1σ) on signal for measurements of CHOCHO and NO2 is 29 pptv and 20 pptv, respectively. We directly compare measurements made with the incoherent broadband cavity enhanced absorption spectrometer with those from cavity ringdown instruments detecting CHOCHO and NO2 at 404 and 532 nm, respectively, and find linear agreement over a wide range of concentrations. The instrument has been tested in the laboratory with both synthetic and real air samples, and the demonstrated sensitivity and specificity suggest a strong potential for field measurements of both CHOCHO and NO2.

  11. Towards traceability in CO2 line strength measurements by TDLAS at 2.7 µm

    NASA Astrophysics Data System (ADS)

    Pogány, Andrea; Ott, Oliver; Werhahn, Olav; Ebert, Volker

    2013-11-01

    Direct tunable diode laser absorption spectroscopy (TDLAS) was combined in this study with metrological principles on the determination of uncertainties to measure the line strengths of the P36e and P34e line of 12C16O2 in the ν1+ν3 band at 2.7 μm. Special emphasis was put on traceability and a concise, well-documented uncertainty assessment. We have quantitatively analyzed the uncertainty contributions of different experimental parameters to the uncertainty of the line strength. Establishment of the wavenumber axis and the gas handling procedure proved to be the two major contributors to the final uncertainty. The obtained line strengths at 296 K are 1.593×10-20 cm/molecule for the P36e and 1.981×10-20 cm/molecule for the P34e line, with relative expanded uncertainties of 1.1% and 1.3%, respectively (k=2, corresponding to a 95% confidence level). The measured line strength values are in agreement with literature data (line strengths listed in the HITRAN and GEISA databases), but show an uncertainty, which is at least a factor of 2 lower.

  12. Two-photon absorption dispersion spectrometer for 1.53 μm eye-safe Doppler LIDAR.

    PubMed

    Vance, J D

    2012-07-01

    Based upon resonant two-photon absorption within a rubidium cell and 780 nm pump light, a birefringent medium for 1.530 μm is induced that changes rapidly with frequency. The birefringence is exploited to build a spectrometer that is capable of measuring the Doppler shift of scattered photons.

  13. Tunable diode laser absorption spectroscopy as method of choice for non-invasive and automated detection of microbial growth in media fills.

    PubMed

    Brueckner, David; Roesti, David; Zuber, Ulrich; Sacher, Meik; Duncan, Derek; Krähenbühl, Stephan; Braissant, Olivier

    2017-05-15

    Tunable diode laser absorption spectroscopy (TDLAS) was evaluated on its potential to detect bacterial growth of contaminated media fill vials. The target was a replacement/ automation of the traditional visual media fill inspection. TDLAS was used to determine non-invasively O 2 and/or CO 2 changes in headspaces of such vials being induced by metabolically active microorganisms. Four different vial formats, 34 microorganisms (inoculation volume<10 cells) and two different media (TSB/FTM) were tested. Applying parallel CO 2 and O 2 headspace measurements all format-organism combinations were detected within <11 days reliably with reproducible results. False negatives were exclusively observed for samples that were intentionally breached with syringes of 0.3mm in diameter. Overall it was shown that TDLAS functionality for a replacement of the visual media fill inspection is given and that investing in further validation and implementation studies is valuable. Nevertheless, some small but vincible challenges remain to have this technology in practical use. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Carbon Dioxide Laser Absorption Spectrometer (CO2LAS) Aircraft Measurements of CO2

    NASA Technical Reports Server (NTRS)

    Christensen, Lance E.; Spiers, Gary D.; Menzies, Robert T.; Jacob, Joseph C.; Hyon, Jason

    2011-01-01

    The Jet Propulsion Laboratory Carbon Dioxide Laser Absorption Spectrometer (CO2LAS) utilizes Integrated Path Differential Absorption (IPDA) at 2.05 microns to obtain CO2 column mixing ratios weighted heavily in the boundary layer. CO2LAS employs a coherent detection receiver and continuous-wave Th:Ho:YLF laser transmitters with output powers around 100 milliwatts. An offset frequency-locking scheme coupled to an absolute frequency reference enables the frequencies of the online and offline lasers to be held to within 200 kHz of desired values. We describe results from 2009 field campaigns when CO2LAS flew on the Twin Otter. We also describe spectroscopic studies aimed at uncovering potential biases in lidar CO2 retrievals at 2.05 microns.

  15. Measurement of Glyoxal Using an Incoherent Broadband Cavity Enhanced Absorption Spectrometer

    NASA Astrophysics Data System (ADS)

    Washenfelder, R. A.; Langford, A. O.; Fuchs, H.; Brown, S. S.

    2008-12-01

    Glyoxal (CHOCHO) is the simplest alpha-dicarbonyl and one of the most prevalent dicarbonyls in the atmosphere. It is formed from the photooxidation of anthropogenic hydrocarbons (e.g. aromatics and acetylene), and is a minor oxidation product of isoprene and other biogenic species. Photolysis of glyoxal is a significant source of HOx (OH + HO2), and there is growing evidence that heterogeneous reactions of glyoxal play an important role in the formation of secondary organic aerosol. We present a novel technique for measurement of glyoxal using cavity enhanced absorption spectroscopy with a broadband light source (IBBCEAS). The output of a Xenon arc lamp is coupled into a 1 m optical cavity, and the spectrum of light exiting the cavity is recorded by a grating spectrometer with a charge- coupled device (CCD) array detector. The mirror reflectivity and effective path lengths are determined from the known Rayleigh scattering of He and dry zero air (N2 + O2). We use least-squares fitting with published reference spectra to simultaneous retrieve glyoxal, nitrogen dioxide (NO2), oxygen dimer (O4) and water (H2O) in the 441 to 469 nm spectral range. For a 1-min sampling time, the precision (±1σ) on signal for measurements of CHOCHO and NO2 is 29 pptv and 20 pptv respectively. We directly compare the incoherent broadband cavity enhanced absorption spectrometer to 404 and 532 nm cavity ringdown instruments for CHOCHO and NO2 detection, and find linear agreement over a wide range of concentrations. We present laboratory measurements of synthetic and real air samples containing CHOCHO and NO2, and discuss the potential for field measurements.

  16. 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.

  17. A Near-Infrared Spectrometer to Measure Zodiacal Light Absorption Spectrum

    NASA Technical Reports Server (NTRS)

    Kutyrev, A. S.; Arendt, R.; Dwek, E.; Kimble, R.; Moseley, S. H.; Rapchun, D.; Silverberg, R. F.

    2010-01-01

    We have developed a high throughput infrared spectrometer for zodiacal light fraunhofer lines measurements. The instrument is based on a cryogenic dual silicon Fabry-Perot etalon which is designed to achieve high signal to noise Fraunhofer line profile measurements. Very large aperture silicon Fabry-Perot etalons and fast camera optics make these measurements possible. The results of the absorption line profile measurements will provide a model free measure of the zodiacal Light intensity in the near infrared. The knowledge of the zodiacal light brightness is crucial for accurate subtraction of zodiacal light foreground for accurate measure of the extragalactic background light after the subtraction of zodiacal light foreground. We present the final design of the instrument and the first results of its performance.

  18. [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.

  19. MASERATI: a RocketBorne tunable diode laser absorption spectrometer.

    PubMed

    Lübken, F J; Dingler, F; von Lucke, H; Anders, J; Riedel, W J; Wolf, H

    1999-09-01

    The MASERATI (middle-atmosphere spectrometric experiment on rockets for analysis of trace-gas influences) instrument is, to our knowledge, the first rocket-borne tunable diode laser absorption spectrometer that was developed for in situ measurements of trace gases in the middle atmosphere. Infrared absorption spectroscopy with lead salt diode lasers is applied to measure water vapor and carbon dioxide in the altitude range from 50 to 90 km and 120 km, respectively. The laser beams are directed into an open multiple-pass absorption setup (total path length 31.7 m) that is mounted on top of a sounding rocket and that is directly exposed to ambient air. The two species are sampled alternately with a sampling time of 7.37 ms, each corresponding to an altitude resolution of approximately 15 m. Frequency-modulation and lock-in techniques are used to achieve high sensitivity. Tests in the laboratory have shown that the instrument is capable of detecting a very small relative absorbance of 10(-4)-10(-5) when integrating spectra for 1 s. The instrument is designed and qualified to resist the mechanical stress occurring during the start of a sounding rocket and to be operational during the cruising phase of the flight when accelerations are very small. Two almost identical versions of the MASERATI instrument were built and were launched on sounding rockets from the Andøya Rocket Range (69 degrees N) in northern Norway on 12 October 1997 and on 31 January 1998. The good technical performance of the instruments during these flights has demonstrated that MASERATI is indeed a new suitable tool to perform rocket-borne in situ measurements in the upper atmosphere.

  20. [Determination of sulfur in plant using a high-resolution continuum source atomic absorption spectrometer].

    PubMed

    Wang, Yu; Li, Jia-xi

    2009-05-01

    A method for the analysis of sulfur (S) in plant by molecular absorption of carbon monosulfide (CS) using a high-resolution continuum source atomic absorption spectrometer (CS AAS) with a fuel-rich air/acetylene flame has been devised. The strong CS absorption band was found around 258 nm. The half-widths of some absorption bands were of the order of picometers, the same as the common atomic absorption lines. The experimental procedure in this study provided optimized instrumental conditions (the ratio of acetylene to air, the burner height) and parameters, and researched the spectral interferences and chemical interferences. The influence of the organic solvents on the CS absorption signals and the different digestion procedures for the determination of sulfur were also investigated. The limit of detection achieved for sulfur was 14 mg x L(-1), using the CS wavelength of 257. 961 nm and a measurement time of 3 s. The accuracy and precision were verified by analysis of two plant standard reference materials. The major applications of this method have been used for the determination of sulfur in plant materials, such as leaves. Compared to the others, this method for the analysis of sulfur is rapid, easy and simple for sulfur determination in plant.

  1. An off Axis Cavity Enhanced Absorption Spectrometer and a Rapid Scan Spectrometer with a Room-Temperature External Cavity Quantum Cascade Laser

    NASA Astrophysics Data System (ADS)

    Liu, Xunchen; Kang, Cheolhwa; Xu, Yunjie

    2009-06-01

    Quantum cascade laser (QCL) is a new type of mid-infrared tunable diode lasers with superior output power and mode quality. Recent developments, such as room temperature operation, wide frequency tunability, and narrow line width, make QCLs an ideal light source for high resolution spectroscopy. Two slit jet infrared spectrometers, namely an off-axis cavity enhanced absorption (CEA) spectrometer and a rapid scan spectrometer with an astigmatic multi-pass cell assembly, have been coupled with a newly purchased room temperature tunable mod-hop-free QCL with a frequency coverage from 1592 cm^{-1} to 1698 cm^{-1} and a scan rate of 0.1 cm^{-1}/ms. Our aim is to utilize these two sensitive spectrometers, that are equipped with a molecular jet expansion, to investigate the chiral molecules-(water)_n clusters. To demonstrate the resolution and sensitivity achieved, the rovibrational transitions of the static N_2O gas and the bending rovibrational transitions of the Ar-water complex, a test system, at 1634 cm^{-1} have been measured. D. Hofstetter and J. Faist in High performance quantum cascade lasers and their applications, Vol.89 Springer-Verlag Berlin & Heidelberg, 2003, pp. 61-98. Y. Xu, X. Liu, Z. Su, R. M. Kulkarni, W. S. Tam, C. Kang, I. Leonov and L. D'Agostino, Proc. Spie, 2009, 722208 (1-11). M. J. Weida and D. J. Nesbitt, J. Chem. Phys. 1997, 106, 3078-3089.

  2. Convenient determination of luminescence quantum yield using a combined electronic absorption and emission spectrometer

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

    Prakash, John; Mishra, Ashok Kumar

    2016-01-15

    It is possible to measure luminescence quantum yield in a facile way, by designing an optical spectrometer capable of obtaining electronic absorption as well as luminescence spectra, with a setup that uses the same light source and detector for both the spectral measurements. Employment of a single light source and single detector enables use of the same correction factor profile for spectral corrections. A suitable instrumental scaling factor is used for adjusting spectral losses.

  3. 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.

  4. Simultaneous gas-phase and total water detection for airborne applications with a multi-channel TDL spectrometer at 1.4 μm and 2.6 μm

    NASA Astrophysics Data System (ADS)

    Buchholz, Bernhard; Afchine, Armin; Klein, Alexander; Barthel, Jochen; Kallweit, Sören; Klostermann, Tim; Krämer, Martina; Schiller, Cornelius; Ebert, Volker

    2013-04-01

    Water vapor measurements especially within clouds are difficult, in particular due to numerous instrument-specific limitations in precision, time resolution and accuracy. Notably the quantification of the ice and gas-phase water content in cirrus clouds, which play an important role in the global climate system, require new high-speed hygrometers concepts which are capable of resolving large water vapor gradients. Previously we demonstrated a stationary concept of a Tunable Diode Laser Absorption Spectroscopy (TDLAS)-based quantification of the ice/liquid water by independent, but simultaneous measurements of A) the gas-phase water in an open-path configuration (optical-path 125 m) and B) the total water in an extractive version with a closed cell (30 m path) after evaporating the condensed water [1]. In this case we used laboratory TDLAS instrumentation in combination with a long absorption paths and applied those to the AIDA cloud camber [2]. Recently we developed an advanced, miniature version of the concept, suitable for mobile field applications and in particular for use on aircrafts. First tests of our new, fiber-coupled open-path TDLAS cell [3] for airborne applications were combined with the experiences of our extractive SEALDH instruments [4] and led to a new, multi-channel, "multi-phase TDL-hygrometer" called "HAI" ("Hygrometer for Atmospheric Investigations"). HAI, which is explicitly designed for the new German HALO (High Altitude and Long Range Research Aircraft) airplane, provides a similar, but improved functionality like the stationary, multi-phase TDLAS developed for AIDA. However HAI comes in a much more compact, six height units, 30 kg, electronics rack for the main unit and with a new, completely fiber-coupled, compact, 21 kg, dual-wavelength open-path TDL-cell which is placed in the aircraft's skin. HAI is much more complex and versatile than the AIDA precursor and can be seen as comprised of four TDL-spectrometers, as it simultaneously

  5. A broadband cavity enhanced absorption spectrometer for aircraft measurements of glyoxal, methylglyoxal, nitrous acid, nitrogen dioxide, and water vapor

    NASA Astrophysics Data System (ADS)

    Min, K.-E.; Washenfelder, R. A.; Dubé, W. P.; Langford, A. O.; Edwards, P. M.; Zarzana, K. J.; Stutz, J.; Lu, K.; Rohrer, F.; Zhang, Y.; Brown, S. S.

    2016-02-01

    We describe a two-channel broadband cavity enhanced absorption spectrometer (BBCEAS) for aircraft measurements of glyoxal (CHOCHO), methylglyoxal (CH3COCHO), nitrous acid (HONO), nitrogen dioxide (NO2), and water (H2O). The instrument spans 361-389 and 438-468 nm, using two light-emitting diodes (LEDs) and a single grating spectrometer with a charge-coupled device (CCD) detector. Robust performance is achieved using a custom optical mounting system, high-power LEDs with electronic on/off modulation, high-reflectivity cavity mirrors, and materials that minimize analyte surface losses. We have successfully deployed this instrument during two aircraft and two ground-based field campaigns to date. The demonstrated precision (2σ) for retrievals of CHOCHO, HONO and NO2 are 34, 350, and 80 parts per trillion (pptv) in 5 s. The accuracy is 5.8, 9.0, and 5.0 %, limited mainly by the available absorption cross sections.

  6. A broadband cavity enhanced absorption spectrometer for aircraft measurements of glyoxal, methylglyoxal, nitrous acid, nitrogen dioxide, and water vapor

    NASA Astrophysics Data System (ADS)

    Min, K.-E.; Washenfelder, R. A.; Dubé, W. P.; Langford, A. O.; Edwards, P. M.; Zarzana, K. J.; Stutz, J.; Lu, K.; Rohrer, F.; Zhang, Y.; Brown, S. S.

    2015-10-01

    We describe a two-channel broadband cavity enhanced absorption spectrometer (BBCEAS) for aircraft measurements of glyoxal (CHOCHO), methylglyoxal (CH3COCHO), nitrous acid (HONO), nitrogen dioxide (NO2), and water (H2O). The instrument spans 361-389 and 438-468 nm, using two light emitting diodes (LEDs) and a grating spectrometer with a charge-coupled device (CCD) detector. Robust performance is achieved using a custom optical mounting system, high power LEDs with electronic on/off modulation, state-of-the-art cavity mirrors, and materials that minimize analyte surface losses. We have successfully deployed this instrument during two aircraft and two ground-based field campaigns to date. The demonstrated precision (2σ) for retrievals of CHOCHO, HONO and NO2 are 34, 350 and 80 pptv in 5 s. The accuracy is 5.8, 9.0 and 5.0 % limited mainly by the available absorption cross sections.

  7. Validation of double-pulse 1572 nm integrated path differential absorption lidar measurement of carbon dioxide

    NASA Astrophysics Data System (ADS)

    Du, Juan; Liu, Jiqiao; Bi, Decang; Ma, Xiuhua; Hou, Xia; Zhu, Xiaolei; Chen, Weibiao

    2018-04-01

    A ground-based double-pulse 1572 nm integrated path differential absorption (IPDA) lidar was developed for carbon dioxide (CO2) column concentrations measurement. The lidar measured the CO2 concentrations continuously by receiving the scattered echo signal from a building about 1300 m away. The other two instruments of TDLAS and in-situ CO2 analyzer measured the CO2 concentrations on the same time. A CO2 concentration measurement of 430 ppm with 1.637 ppm standard error was achieved.

  8. Effective optical path length for tandem diffuse cubic cavities as gas absorption cell

    NASA Astrophysics Data System (ADS)

    Yu, J.; Gao, Q.; Zhang, Y. G.; Zhang, Z. G.; Wu, S. H.

    2014-12-01

    Tandem diffuse cubic cavities designed by connecting two single diffuse cubic-shaped cavities, A and B, with an aperture (port fraction fap) in the middle of the connecting baffle was developed as a gas absorption cell. The effective optical path length (EOPL) was evaluated by comparing the oxygen absorption signal in the cavity and in air based on tunable diode laser absorption spectroscopy (TDLAS). Experimental results manifested an enhancement of EOPL for the tandem diffuse cubic cavities as the decrease of fap and can be expressed as the sum of EOPL of two single cubic cavities at fap < 0.01, which coincided well with theoretical analysis. The simulating EOPL was smaller than experimental results at fap > 0.01, which indicated that back scattering light from cavity B to cavity A cannot be ignored at this condition.

  9. Analytical characteristics of a continuum-source tungsten coil atomic absorption spectrometer.

    PubMed

    Rust, Jennifer A; Nóbrega, Joaquim A; Calloway, Clifton P; Jones, Bradley T

    2005-08-01

    A continuum-source tungsten coil electrothermal atomic absorption spectrometer has been assembled, evaluated, and employed in four different applications. The instrument consists of a xenon arc lamp light source, a tungsten coil atomizer, a Czerny-Turner high resolution monochromator, and a linear photodiode array detector. This instrument provides simultaneous multi-element analyses across a 4 nm spectral window with a resolution of 0.024 nm. Such a device might be useful in many different types of analyses. To demonstrate this broad appeal, four very different applications have been evaluated. First of all, the temperature of the gas phase was measured during the atomization cycle of the tungsten coil, using tin as a thermometric element. Secondly, a summation approach for two absorption lines for aluminum falling within the same spectral window (305.5-309.5 nm) was evaluated. This approach improves the sensitivity without requiring any additional preconcentration steps. The third application describes a background subtraction technique, as it is applied to the analysis of an oil emulsion sample. Finally, interference effects caused by Na on the atomization of Pb were studied. The simultaneous measurements of Pb and Na suggests that negative interference arises at least partially from competition between Pb and Na atoms for H2 in the gas phase.

  10. Fire Suppression Properties of Very Fine Water Mist

    DTIC Science & Technology

    2005-01-01

    with the University of Heidelberg, developed an in situ oxygen sensor based on tunable diode laser absorption spectroscopy ( TDLAS ) to provide absolute... oxygen number densities in the presence of mist.3 Th e TDLAS oxygen sensor provides real-time, calibra- tion-free, quantitative oxygen ...Determination of Molecular Oxygen Concentrations in Full-Scale Fire Suppression Tests Using TDLAS ,” Proc. Combust. Inst. 29, 353-360 (2002).

  11. Measurements of axisymmetric temperature and H2O concentration distributions on a circular flat flame burner based on tunable diode laser absorption tomography

    NASA Astrophysics Data System (ADS)

    Xia, Huihui; Kan, Ruifeng; Xu, Zhenyu; Liu, Jianguo; He, Yabai; Yang, Chenguang; Chen, Bing; Wei, Min; Yao, Lu; Zhang, Guangle

    2016-10-01

    In this paper, the reconstruction of axisymmetric temperature and H2O concentration distributions in a flat flame burner is realized by tunable diode laser absorption spectroscopy (TDLAS) and filtered back-projection (FBP) algorithm. Two H2O absorption transitions (7154.354/7154.353 cm-1 and 7467.769 cm-1) are selected as line pair for temperature measurement, and time division multiplexing technology is adopted to scan this two H2O absorption transitions simultaneously at 1 kHz repetition rate. In the experiment, FBP algorithm can be used for reconstructing axisymmetric distributions of flow field parameters with only single view parallel-beam TDLAS measurements, and the same data sets from the given parallel beam are used for other virtual projection angles and beams scattered between 0° and 180°. The real-time online measurements of projection data, i.e., integrated absorbance both for pre-selected transitions on CH4/air flat flame burner are realized by Voigt on-line fitting, and the fitting residuals are less than 0.2%. By analyzing the projection data from different views based on FBP algorithm, the distributions of temperature and concentration along radial direction can be known instantly. The results demonstrate that the system and the proposed innovative FBP algorithm are capable for accurate reconstruction of axisymmetric temperature and H2O concentration distribution in combustion systems and facilities.

  12. Hydrocarbon-Fueled Scramjet Research at Hypersonic Mach Numbers

    DTIC Science & Technology

    2005-03-31

    oxide O atomic oxygen 02 molecular oxygen OH hydroxyl radical ppm parts per million PD photodiode PLLF planar laser-induced fluorescence PMT...photomultiplier tube RAM random access memory RANS Reynolds-averaged Navier-Stokes RET rotational energy transfer TDLAS tunable diode laser absorption...here extend this knowledge base to flight at Mach 11.5. Griffiths (2004) used a tunable diode laser absorption spectroscopy ( TDLAS ) system to measure

  13. Laser-Based Measurements of OH, Temperature, and Water Vapor Concentration in a Hydrocarbon-Fueled Scramjet (POSTPRINT)

    DTIC Science & Technology

    2008-07-01

    hours. The detector signals are post-processed with a software lock-in amplifier to recover the WMS-1f and WMS-2f signals. The TDLAS sensor utilizes...Figure 6. Schematic of TDLAS sensor for temperature and water vapor concentration. Fiber Diode lasers Grating Fiber Detectors Demultiplexer Multiplexer...within the combustor. Tunable diode laser- based absorption spectroscopy ( TDLAS ) is used to measure water vapor concentration and static temperature near

  14. A combined application of tunable diode laser absorption spectroscopy and isothermal micro-calorimetry for calorespirometric analysis.

    PubMed

    Brueckner, David; Solokhina, Anna; Krähenbühl, Stephan; Braissant, Olivier

    2017-08-01

    Calorespirometry is the simultaneous analysis of the rate of heat emission (R q ), O 2 consumption (R O2 ) and CO 2 production (R CO2 ) by living systems such as tissues or organism cultures. The analysis provides useful knowledge about thermodynamic parameters relevant for e.g. biotechnology where parameter based yield maximization (fermentation) is relevant. The determination of metabolism related heat emission is easy and normally done by a calorimeter. However, measuring the amount of consumed O 2 and produced CO 2 can be more challenging, as additional preparation or instrumentation might be needed. Therefore, tunable diode laser absorption spectroscopy (TDLAS) was investigated as an alternative approach for respirometric analysis in order to facilitate the data collection procedure. The method determines by a spectroscopic laser non-invasively CO 2 and O 2 gas concentration changes in the respective vial headspaces. The gathered growth data from Pseudomonas aeruginosa cultured in two different scarce media was used to compute respiratory quotient (RQ) and calorespirometric ratios (CR CO2 [R q /R CO2 ], CR O2 [R q /R O2 ]). A comparison of the computed (experimental) values (for RQ, CR CO2 and CR O2 ) with values reported in the literature confirmed the appropriateness of TDLAS in calorespirometric studies. Thus, it could be demonstrated that TDLAS is a well-performing and convenient way to evaluate non-invasively respiratory rates during calorespirometric studies. Therefore, the technique is definitively worth to be investigated further for its potential use in research and in diverse productive environments. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Assessment of the performance of a compact concentric spectrometer system for Atmospheric Differential Optical Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Whyte, C.; Leigh, R. J.; Lobb, D.; Williams, T.; Remedios, J. J.; Cutter, M.; Monks, P. S.

    2009-12-01

    A breadboard demonstrator of a novel UV/VIS grating spectrometer has been developed based upon a concentric arrangement of a spherical meniscus lens, concave spherical mirror and curved diffraction grating suitable for a range of atmospheric remote sensing applications from the ground or space. The spectrometer is compact and provides high optical efficiency and performance benefits over traditional instruments. The concentric design is capable of handling high relative apertures, owing to spherical aberration and comma being near zero at all surfaces. The design also provides correction for transverse chromatic aberration and distortion, in addition to correcting for the distortion called "smile", the curvature of the slit image formed at each wavelength. These properties render this design capable of superior spectral and spatial performance with size and weight budgets significantly lower than standard configurations. This form of spectrometer design offers the potential for exceptionally compact instrument for differential optical absorption spectroscopy (DOAS) applications from LEO, GEO, HAP or ground-based platforms. The breadboard demonstrator has been shown to offer high throughput and a stable Gaussian line shape with a spectral range from 300 to 450 nm at 0.5 nm resolution, suitable for a number of typical DOAS applications.

  16. JPL Fourier transform ultraviolet spectrometer

    NASA Technical Reports Server (NTRS)

    Cageao, R. P.; Friedl, R. R.; Sander, Stanley P.; Yung, Y. L.

    1994-01-01

    The Fourier Transform Ultraviolet Spectrometer (FTUVS) is a new high resolution interferometric spectrometer for multiple-species detection in the UV, visible and near-IR. As an OH sensor, measurements can be carried out by remote sensing (limb emission and column absorption), or in-situ sensing (long-path absorption or laser-induced fluorescence). As a high resolution detector in a high repetition rate (greater than 10 kHz) LIF system, OH fluorescence can be discriminated against non-resonant background emission and laser scatter, permitting (0, 0) excitation.

  17. Measurements of water molecule density by tunable diode laser absorption spectroscopy in dielectric barrier discharges with gas-water interface

    NASA Astrophysics Data System (ADS)

    Tachibana, Kunihide; Nakamura, Toshihiro; Kawasaki, Mitsuo; Morita, Tatsuo; Umekawa, Toyofumi; Kawasaki, Masahiro

    2018-01-01

    We measured water molecule (H2O) density by tunable diode-laser absorption spectroscopy (TDLAS) for applications in dielectric barrier discharges (DBDs) with a gas-water interface. First, the effects of water temperature and presence of gas flow were tested using a Petri dish filled with water and a gas injection nozzle. Second, the TDLAS system was applied to the measurements of H2O density in two types of DBDs; one was a normal (non-inverted) type with a dielectric-covered electrode above a water-filled counter electrode and the other was an inverted type with a water-suspending mesh electrode above a dielectric-covered counter electrode. The H2O density in the normal DBD was close to the density estimated from the saturated vapor pressure, whereas the density in the inverted DBD was about half of that in the former type. The difference is attributed to the upward gas flow in the latter type, that pushes the water molecules up towards the gas-water interface.

  18. Assessment of the performance of a compact concentric spectrometer system for Atmospheric Differential Optical Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Whyte, C.; Leigh, R. J.; Lobb, D.; Williams, T.; Remedios, J. J.; Cutter, M.; Monks, P. S.

    2009-08-01

    A breadboard demonstrator of a novel UV/VIS grating spectrometer for atmospheric research has been developed based upon a concentric arrangement of a spherical meniscus lens, concave spherical mirror and curved diffraction grating suitable for a range of remote sensing applications from the ground or space. The spectrometer is compact and provides high optical efficiency and performance benefits over traditional instruments. The concentric design is capable of handling high relative apertures, owing to spherical aberration and coma being near zero at all surfaces. The design also provides correction for transverse chromatic aberration and distortion, in addition to correcting for the distortion called "smile", the curvature of the slit image formed at each wavelength. These properties render this design capable of superior spectral and spatial performance with size and weight budgets significantly lower than standard configurations. This form of spectrometer design offers the potential for an exceptionally compact instrument for differential optical absorption spectroscopy (DOAS) applications particularly from space (LEO, GEO orbits) and from HAPs or ground-based platforms. The breadboard demonstrator has been shown to offer high throughput and a stable Gaussian line shape with a spectral range from 300 to 450 nm at better than 0.5 nm resolution, suitable for a number of typical DOAS applications.

  19. The airborne Laser Absorption Spectrometer - A new instrument of remote measurement of atmospheric trace gases

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

    The Laser Absorption Spectrometer is a portable instrument developed by JPL for remote measurement of trace gases from an aircraft platform. It contains two carbon dioxide lasers, two optical heterodyne receivers, appropriate optics to aim the lasers at the ground and detect the backscattered energy, and signal processing and recording electronics. Operating in the differential-absorption mode, it is possible to monitor one atmospheric gas at a time and record the data in real time. The system can presently measure ozone, ethylene, water vapor, and chlorofluoromethanes with high sensitivity. Airborne measurements were made in early 1977 from the NASA/JPL twin-engine Beechcraft and in May 1977 from the NASA Convair 990 during the ASSESS-II Shuttle Simulation Study. These flights resulted in measurements of ozone concentrations in the lower troposphere which were compared with ground-based values provided by the Air Pollution Control District. This paper describes the details of the instrument and results of the airborne measurements.

  20. [Study of high temperature water vapor concentration measurement method based on absorption spectroscopy].

    PubMed

    Chen, Jiu-ying; Liu, Jian-guo; He, Jun-feng; He, Ya-bai; Zhang, Guang-le; Xu, Zhen-yu; Gang, Qiang; Wang, Liao; Yao, Lu; Yuan, Song; Ruan, Jun; Dai, Yun-hai; Kan, Rui-feng

    2014-12-01

    Tunable diode laser absorption spectroscopy (TDLAS) has been developed to realize the real-time and dynamic measurement of the combustion temperature, gas component concentration, velocity and other flow parameters, owing to its high sensitivity, fast time response, non-invasive character and robust nature. In order to obtain accurate water vapor concentration at high temperature, several absorption spectra of water vapor near 1.39 μm from 773 to 1273 K under ordinary pressure were recorded in a high temperature experiment setup using a narrow band diode laser. The absorbance of high temperature absorption spectra was calculated by combined multi-line nonlinear least squares fitting method. Two water vapor absorption lines near 7154.35 and 7157.73 cm(-1) were selected for measurement of water vapor at high temperature. A model method for high temperature water vapor concentration was first proposed. Water vapor concentration from the model method at high temperature is in accordance with theoretical reasoning, concentration measurement standard error is less than 0.2%, and the relative error is less than 6%. The feasibility of this measuring method is verified by experiment.

  1. Characterizing a Quantum Cascade Tunable Infrared Laser Differential Absorption Spectrometer (QC-TILDAS) for Measurements of Atmospheric Ammonia

    NASA Astrophysics Data System (ADS)

    Ellis, R.; Murphy, J. G.; van Haarlem, R.; Pattey, E.; O'Brien, J.

    2009-05-01

    A compact, fast response Quantum Cascade Tunable Infrared Laser Differential Absorption Spectrometer (QC- TILDAS) for measurements of ammonia has been evaluated under both laboratory and field conditions. Absorption of radiation from a pulsed, thermoelectrically cooled QC laser occurs at reduced pressure in a 76 m path length, 0.5 L volume multiple pass absorption cell. Detection is achieved using a thermoelectrically cooled HgCdTe infrared detector. A novel sampling technique was used, consisting of a short, heated, quartz inlet with a hydrophobic coating to minimize the adsorption of ammonia to surfaces. The inlet contains a critical orifice that reduces the pressure, a virtual impactor for separation of particles and additional ports for delivering ammonia free background air and calibration gas standards. This instrument has been found to have a detection limit of 0.3 ppb with a time resolution of 1 s. The sampling technique has been compared to the results of a conventional lead salt Tunable Diode Laser (TDL) absorption spectrometer during a laboratory intercomparison. Various lengths and types of sample inlet tubing material, heated and unheated, under dry and ambient humidity conditions with ammonia concentrations ranging from 10-1000 ppb were investigated. Preliminary analysis suggests the time response improves with the use of short, PFA tubing sampling lines. No significant improvement was observed when using a heated sampling line and humidity was seen to play an important role on the bi-exponential decay of ammonia. A field intercomparison of the QC-TILDAS with a modified Thermo 42C chemiluminescence based analyzer was also performed at Environment Canada's Centre for Atmospheric Research Experiments (CARE) in the rural town of Egbert, ON between May-July 2008. Background tests and calibrations using two different permeation tube sources and an ammonia gas cylinder were regularly carried out throughout the study. Results indicate a very good correlation

  2. Retrieval and molecule sensitivity studies for the global ozone monitoring experiment and the scanning imaging absorption spectrometer for atmospheric chartography

    NASA Technical Reports Server (NTRS)

    Chance, Kelly V.; Burrows, John P.; Schneider, Wolfgang

    1991-01-01

    The Global Ozone Monitoring Experiment (GOME) and the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) are diode based spectrometers that will make atmospheric constituent and aerosol measurements from European satellite platforms beginning in the mid 1990's. GOME measures the atmosphere in the UV and visible in nadir scanning, while SCIAMACHY performs a combination of nadir, limb, and occultation measurements in the UV, visible, and infrared. A summary is presented of the sensitivity studies that were performed for SCIAMACHY measurements. As the GOME measurement capability is a subset of the SCIAMACHY measurement capability, the nadir, UV, and visible portion of the studies is shown to apply to GOME as well.

  3. Field campaigns of the autonomous, closed-path, airborne TDLAS Hygrometer SEALDH-II and traceability to the German Primary Humidity Standards.

    NASA Astrophysics Data System (ADS)

    Buchholz, Bernhard; Ebert, Volker

    2014-05-01

    calibration link to any industrial or research laboratory hygrometer. To establish metrological traceability in field and particular in airborne hygrometers is however challenging and requires fast, field-compatible, metrologically qualified transfer hygrometry standards to link the metrological and the environmental sciences water scales. The SEALDH (Selective Extractive Airborne Laser Diode Hygrometer) development started 3 years ago and aims at filling this gap by using Tunable Diode Laser Absorption Spectroscopy (TDLAS) with a special, calibration-free data evaluation [1]. Previously developed, laboratory-based TDLAS instruments, such as [2] [3], were starting points to develop an autonomously operating, extractive water vapor sensor in a compact 19' 4 HU form factor. This new airborne package and far-reaching developments [4] in hard- and software allow an autonomous, low maintenance, airborne operation. SEALDH-II can be used in a calibration-free field sensor mode (with an absolute, metrologically defined uncertainty of 4.3% +- 3ppmv). The response time is mainly limited by the gas flow and significantly below 1 sec with a precision down to 0.08 ppmv (1σ, 1sec) measured at 600 ppmv and 1000 hPa. The excellent long-term stability of SEALDH-II (

  4. ATLAS: Airborne Tunable Laser Absorption Spectrometer for stratospheric trace gas measurements

    NASA Technical Reports Server (NTRS)

    Loewenstein, Max; Podolske, James R.; Strahan, Susan E.

    1990-01-01

    The ATLAS instrument is an advanced technology diode laser based absorption spectrometer designed specifically for stratospheric tracer studies. This technique was used in the acquisition of N2O tracer data sets on the Airborne Antarctic Ozone Experiment and the Airborne Arctic Stratospheric Expedition. These data sets have proved valuable for comparison with atmospheric models, as well as in assisting in the interpretation of the entire ensemble of chemical and meteorological data acquired on these two field studies. The N2O dynamical tracer data set analysis revealed several ramifications concerning the polar atmosphere: the N2O/NO(y) correlation, which is used as a tool to study denitrification in the polar vertex; the N2O Southern Hemisphere morphology, showing subsidence in the winter polar vortex; and the value of the N2O measurements in the interpretation of ClO, O3, and NO(y) measurements and of the derived dynamical tracer, potential vorticity. Field studies also led to improved characterization of the instrument and to improved accuracy.

  5. A fibre-coupled UHV-compatible variable angle reflection-absorption UV/visible spectrometer

    NASA Astrophysics Data System (ADS)

    Stubbing, J. W.; Salter, T. L.; Brown, W. A.; Taj, S.; McCoustra, M. R. S.

    2018-05-01

    We present a novel UV/visible reflection-absorption spectrometer for determining the refractive index, n, and thicknesses, d, of ice films. Knowledge of the refractive index of these films is of particular relevance to the astrochemical community, where they can be used to model radiative transfer and spectra of various regions of space. In order to make these models more accurate, values of n need to be recorded under astronomically relevant conditions, that is, under ultra-high vacuum (UHV) and cryogenic cooling. Several design considerations were taken into account to allow UHV compatibility combined with ease of use. The key design feature is a stainless steel rhombus coupled to an external linear drive (z-shift) allowing a variable reflection geometry to be achieved, which is necessary for our analysis. Test data for amorphous benzene ice are presented as a proof of concept, the film thickness, d, was found to vary linearly with surface exposure, and a value for n of 1.43 ± 0.07 was determined.

  6. A Compact Tunable Diode Laser Absorption Spectrometer to Monitor CO2 at 2.7 μm Wavelength in Hypersonic Flows

    PubMed Central

    Vallon, Raphäel; Soutadé, Jacques; Vérant, Jean-Luc; Meyers, Jason; Paris, Sébastien; Mohamed, Ajmal

    2010-01-01

    Since the beginning of the Mars planet exploration, the characterization of carbon dioxide hypersonic flows to simulate a spaceship’s Mars atmosphere entry conditions has been an important issue. We have developed a Tunable Diode Laser Absorption Spectrometer with a new room-temperature operating antimony-based distributed feedback laser (DFB) diode laser to characterize the velocity, the temperature and the density of such flows. This instrument has been tested during two measurement campaigns in a free piston tunnel cold hypersonic facility and in a high enthalpy arc jet wind tunnel. These tests also demonstrate the feasibility of mid-infrared fiber optics coupling of the spectrometer to a wind tunnel for integrated or local flow characterization with an optical probe placed in the flow. PMID:22219703

  7. A compact tunable diode laser absorption spectrometer to monitor CO2 at 2.7 μm wavelength in hypersonic flows.

    PubMed

    Vallon, Raphäel; Soutadé, Jacques; Vérant, Jean-Luc; Meyers, Jason; Paris, Sébastien; Mohamed, Ajmal

    2010-01-01

    Since the beginning of the Mars planet exploration, the characterization of carbon dioxide hypersonic flows to simulate a spaceship's Mars atmosphere entry conditions has been an important issue. We have developed a Tunable Diode Laser Absorption Spectrometer with a new room-temperature operating antimony-based distributed feedback laser (DFB) diode laser to characterize the velocity, the temperature and the density of such flows. This instrument has been tested during two measurement campaigns in a free piston tunnel cold hypersonic facility and in a high enthalpy arc jet wind tunnel. These tests also demonstrate the feasibility of mid-infrared fiber optics coupling of the spectrometer to a wind tunnel for integrated or local flow characterization with an optical probe placed in the flow.

  8. Methods for Retrievals of CO2 Mixing Ratios from JPL Laser Absorption Spectrometer Flights During a Summer 2011 Campaign

    NASA Technical Reports Server (NTRS)

    Menzies, Robert T.; Spiers, Gary D.; Jacob, Joseph C.

    2013-01-01

    The JPL airborne Laser Absorption Spectrometer instrument has been flown several times in the 2007-2011 time frame for the purpose of measuring CO2 mixing ratios in the lower atmosphere. This instrument employs CW laser transmitters and coherent detection receivers in the 2.05- micro m spectral region. The Integrated Path Differential Absorption (IPDA) method is used to retrieve weighted CO2 column mixing ratios. We present key features of the evolving LAS signal processing and data analysis algorithms and the calibration/validation methodology. Results from 2011 flights in various U.S. locations include observed mid-day CO2 drawdown in the Midwest and high spatial resolution plume detection during a leg downwind of the Four Corners power plant in New Mexico.

  9. The nonlinear light output of NaI(Tl) detectors in the Modular Total Absorption Spectrometer

    DOE PAGES

    Rasco, B. C.; Fijałkowska, A.; Karny, M.; ...

    2015-04-08

    New detector array, the Modular Total Absorption Spectrometer (MTAS),was commissioned at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Lab(ORNL).Total absorption gamma spectra measured with MTAS are expected to improve beta-feeding patterns and beta strength functions in fission products.MTAS is constructed out of hexagonal NaI(Tl) detectors with a unique central module surrounded by 18 identical crystals assembled in three rings. The total NaI(Tl) mass of MTAS is over1000 kg.The response of the central and other 18 MTAS modules to -radiation was simulated using the GEANT4 tool kit modified to analyze the nonlinear light output of NaI(Tl).A detailedmore » description oftheGEANT4modifications madeisdiscussed.SimulatedenergyresolutionofMTAS modules is found to agree well with the measurements for single transitions of 662keV (137Cs) with 8.2% full width half maximum (FWHM),835keV (54Mn) with FWHM of 7.5% FWHM, and 1115keV (65Zn) with FWHM of 6.5%.Simulations of single and multiple -rays from 60Co are also discussed.« less

  10. Methanogenic activity tests by Infrared Tunable Diode Laser Absorption Spectroscopy.

    PubMed

    Martinez-Cruz, Karla; Sepulveda-Jauregui, Armando; Escobar-Orozco, Nayeli; Thalasso, Frederic

    2012-10-01

    Methanogenic activity (MA) tests are commonly carried out to estimate the capability of anaerobic biomass to treat effluents, to evaluate anaerobic activity in bioreactors or natural ecosystems, or to quantify inhibitory effects on methanogenic activity. These activity tests are usually based on the measurement of the volume of biogas produced by volumetric, pressure increase or gas chromatography (GC) methods. In this study, we present an alternative method for non-invasive measurement of methane produced during activity tests in closed vials, based on Infrared Tunable Diode Laser Absorption Spectroscopy (MA-TDLAS). This new method was tested during model acetoclastic and hydrogenotrophic methanogenic activity tests and was compared to a more traditional method based on gas chromatography. From the results obtained, the CH(4) detection limit of the method was estimated to 60 ppm and the minimum measurable methane production rate was estimated to 1.09(.)10(-3) mg l(-1) h(-1), which is below CH(4) production rate usually reported in both anaerobic reactors and natural ecosystems. Additionally to sensitivity, the method has several potential interests compared to more traditional methods among which short measurements time allowing the measurement of a large number of MA test vials, non-invasive measurements avoiding leakage or external interferences and similar cost to GC based methods. It is concluded that MA-TDLAS is a promising method that could be of interest not only in the field of anaerobic digestion but also, in the field of environmental ecology where CH(4) production rates are usually very low. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. Airborne imaging spectrometer data of the Ruby Mountains, Montana: Mineral discrimination using relative absorption band-depth images

    USGS Publications Warehouse

    Crowley, J.K.; Brickey, D.W.; Rowan, L.C.

    1989-01-01

    Airborne imaging spectrometer data collected in the near-infrared (1.2-2.4 ??m) wavelength range were used to study the spectral expression of metamorphic minerals and rocks in the Ruby Mountains of southwestern Montana. The data were analyzed by using a new data enhancement procedure-the construction of relative absorption band-depth (RBD) images. RBD images, like bandratio images, are designed to detect diagnostic mineral absorption features, while minimizing reflectance variations related to topographic slope and albedo differences. To produce an RBD image, several data channels near an absorption band shoulder are summed and then divided by the sum of several channels located near the band minimum. RBD images are both highly specific and sensitive to the presence of particular mineral absorption features. Further, the technique does not distort or subdue spectral features as sometimes occurs when using other data normalization methods. By using RBD images, a number of rock and soil units were distinguished in the Ruby Mountains including weathered quartz - feldspar pegmatites, marbles of several compositions, and soils developed over poorly exposed mica schists. The RBD technique is especially well suited for detecting weak near-infrared spectral features produced by soils, which may permit improved mapping of subtle lithologic and structural details in semiarid terrains. The observation of soils rich in talc, an important industrial commodity in the study area, also indicates that RBD images may be useful for mineral exploration. ?? 1989.

  12. Measurements on NASA Langley Durable Combustor Rig by TDLAT: Preliminary Results

    NASA Technical Reports Server (NTRS)

    Busa, Kristin; Ellison, Erik N.; McGovern, Brian J.; McDaniel, James C.; Diskin, Glenn S.; DePiro, Maxwell J.; Capriotti, Diego P.; Gaffney, Richard L.

    2013-01-01

    Detailed knowledge of the internal structure of high-enthalpy flows can provide valuable insight to the performance of scramjet combustors. Tunable Diode Laser Absorption Spectroscopy (TDLAS) is often employed to measure temperature and species concentration. However, TDLAS is a path-integrated line-of-sight (LOS) measurement, and thus does not produce spatially resolved distributions. Tunable Diode Laser Absorption Tomography (TDLAT) is a non-intrusive measurement technique for determining two-dimensional spatially resolved distributions of temperature and species concentration in high enthalpy flows. TDLAT combines TDLAS with tomographic image reconstruction. Several separate line-of-sight TDLAS measurements are analyzed in order to produce highly resolved temperature and species concentration distributions. Measurements have been collected at the University of Virginia's Supersonic Combustion Facility (UVaSCF) as well as at the NASA Langley Direct-Connect Supersonic Combustion Test Facility (DCSCTF). Measurements collected at the DCSCTF required significant modifications to system hardware and software designs due to its larger measurement area and shorter test duration. Initial LOS measurements from the NASA Langley DCSCTF operating at an equivalence ratio of 0.5 are presented. Results show the capability of TDLAT to adapt to several experimental setups and test parameters.

  13. Direct determination of total sulfur in wine using a continuum-source atomic-absorption spectrometer and an air-acetylene flame.

    PubMed

    Huang, Mao Dong; Becker-Ross, Helmut; Florek, Stefan; Heitmann, Uwe; Okruss, Michael

    2005-08-01

    Determination of sulfur in wine is an important analytical task, particularly with regard to food safety legislation, wine trade, and oenology. Hitherto existing methods for sulfur determination all have specific drawbacks, for example high cost and time consumption, poor precision or selectivity, or matrix effects. In this paper a new method, with low running costs, is introduced for direct, reliable, rapid, and accurate determination of the total sulfur content of wine samples. The method is based on measurement of the molecular absorption of carbon monosulfide (CS) in an ordinary air-acetylene flame by using a high-resolution continuum-source atomic-absorption spectrometer including a novel high-intensity short-arc xenon lamp. First results for total sulfur concentrations in different wine samples were compared with data from comparative ICP-MS measurements. Very good agreement within a few percent was obtained.

  14. Laser absorption spectroscopy of water vapor confined in nanoporous alumina: wall collision line broadening and gas diffusion dynamics.

    PubMed

    Svensson, Tomas; Lewander, Märta; Svanberg, Sune

    2010-08-02

    We demonstrate high-resolution tunable diode laser absorption spectroscopy (TDLAS) of water vapor confined in nanoporous alumina. Strong multiple light scattering results in long photon pathlengths (1 m through a 6 mm sample). We report on strong line broadening due to frequent wall collisions (gas-surface interactions). For the water vapor line at 935.685 nm, the HWHM of confined molecules are about 4.3 GHz as compared to 2.9 GHz for free molecules (atmospheric pressure). Gas diffusion is also investigated, and in contrast to molecular oxygen (that moves rapidly in and out of the alumina), the exchange of water vapor is found very slow.

  15. Tunable diode laser absorption spectroscopy-based tomography system for on-line monitoring of two-dimensional distributions of temperature and H2O mole fraction.

    PubMed

    Xu, Lijun; Liu, Chang; Jing, Wenyang; Cao, Zhang; Xue, Xin; Lin, Yuzhen

    2016-01-01

    To monitor two-dimensional (2D) distributions of temperature and H2O mole fraction, an on-line tomography system based on tunable diode laser absorption spectroscopy (TDLAS) was developed. To the best of the authors' knowledge, this is the first report on a multi-view TDLAS-based system for simultaneous tomographic visualization of temperature and H2O mole fraction in real time. The system consists of two distributed feedback (DFB) laser diodes, a tomographic sensor, electronic circuits, and a computer. The central frequencies of the two DFB laser diodes are at 7444.36 cm(-1) (1343.3 nm) and 7185.6 cm(-1) (1391.67 nm), respectively. The tomographic sensor is used to generate fan-beam illumination from five views and to produce 60 ray measurements. The electronic circuits not only provide stable temperature and precise current controlling signals for the laser diodes but also can accurately sample the transmitted laser intensities and extract integrated absorbances in real time. Finally, the integrated absorbances are transferred to the computer, in which the 2D distributions of temperature and H2O mole fraction are reconstructed by using a modified Landweber algorithm. In the experiments, the TDLAS-based tomography system was validated by using asymmetric premixed flames with fixed and time-varying equivalent ratios, respectively. The results demonstrate that the system is able to reconstruct the profiles of the 2D distributions of temperature and H2O mole fraction of the flame and effectively capture the dynamics of the combustion process, which exhibits good potential for flame monitoring and on-line combustion diagnosis.

  16. Tunable diode laser absorption spectroscopy-based tomography system for on-line monitoring of two-dimensional distributions of temperature and H2O mole fraction

    NASA Astrophysics Data System (ADS)

    Xu, Lijun; Liu, Chang; Jing, Wenyang; Cao, Zhang; Xue, Xin; Lin, Yuzhen

    2016-01-01

    To monitor two-dimensional (2D) distributions of temperature and H2O mole fraction, an on-line tomography system based on tunable diode laser absorption spectroscopy (TDLAS) was developed. To the best of the authors' knowledge, this is the first report on a multi-view TDLAS-based system for simultaneous tomographic visualization of temperature and H2O mole fraction in real time. The system consists of two distributed feedback (DFB) laser diodes, a tomographic sensor, electronic circuits, and a computer. The central frequencies of the two DFB laser diodes are at 7444.36 cm-1 (1343.3 nm) and 7185.6 cm-1 (1391.67 nm), respectively. The tomographic sensor is used to generate fan-beam illumination from five views and to produce 60 ray measurements. The electronic circuits not only provide stable temperature and precise current controlling signals for the laser diodes but also can accurately sample the transmitted laser intensities and extract integrated absorbances in real time. Finally, the integrated absorbances are transferred to the computer, in which the 2D distributions of temperature and H2O mole fraction are reconstructed by using a modified Landweber algorithm. In the experiments, the TDLAS-based tomography system was validated by using asymmetric premixed flames with fixed and time-varying equivalent ratios, respectively. The results demonstrate that the system is able to reconstruct the profiles of the 2D distributions of temperature and H2O mole fraction of the flame and effectively capture the dynamics of the combustion process, which exhibits good potential for flame monitoring and on-line combustion diagnosis.

  17. The 2014 ASCENDS Field Campaign - a Carbon Dioxide Laser Absorption Spectrometer Perspective

    NASA Astrophysics Data System (ADS)

    Spiers, G. D.; Menzies, R. T.; Jacob, J. C.; Geier, S.; Fregoso, S. F.

    2014-12-01

    NASA's ASCENDS mission has been flying several candidate lidar instruments on board the NASA DC-8 aircraft to obtain column integrated measurements of Carbon Dioxide. Each instrument uses a different approach to making the measurement and combined they have allowed for the informed development of the ASCENDS mission measurement requirements(1). The JPL developed Carbon Dioxide Laser Absorption Spectrometer, CO2LAS is one of these instruments. The CO2LAS measures the weighted, column averaged carbon dioxide between the aircraft and the ground using a continuous-wave heterodyne technique. The instrument operates at a 2.05 micron wavelength optimized for enhancing sensitivity to boundary layer carbon dioxide. Since the 2013 field campaign the instrument has undergone significant upgrades that improve the data collection efficiency and instrument stability and has recently been re-integrated onto the NASA DC-8 for the August 2014 ASCENDS field campaign. This presentation will summarize the instrument and algorithm improvements and review the 2014 field campaign flights and preliminary results. (1) Abshire, J.B. et al., "An overview of NASA's ASCENDS Mission lidar measurement requirements", submitted to 2014 Fall AGU Conference.

  18. Tunable diode laser absorption spectroscopy-based tomography system for on-line monitoring of two-dimensional distributions of temperature and H{sub 2}O mole fraction

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

    Xu, Lijun, E-mail: lijunxu@buaa.edu.cn; Liu, Chang; Jing, Wenyang

    2016-01-15

    To monitor two-dimensional (2D) distributions of temperature and H{sub 2}O mole fraction, an on-line tomography system based on tunable diode laser absorption spectroscopy (TDLAS) was developed. To the best of the authors’ knowledge, this is the first report on a multi-view TDLAS-based system for simultaneous tomographic visualization of temperature and H{sub 2}O mole fraction in real time. The system consists of two distributed feedback (DFB) laser diodes, a tomographic sensor, electronic circuits, and a computer. The central frequencies of the two DFB laser diodes are at 7444.36 cm{sup −1} (1343.3 nm) and 7185.6 cm{sup −1} (1391.67 nm), respectively. The tomographicmore » sensor is used to generate fan-beam illumination from five views and to produce 60 ray measurements. The electronic circuits not only provide stable temperature and precise current controlling signals for the laser diodes but also can accurately sample the transmitted laser intensities and extract integrated absorbances in real time. Finally, the integrated absorbances are transferred to the computer, in which the 2D distributions of temperature and H{sub 2}O mole fraction are reconstructed by using a modified Landweber algorithm. In the experiments, the TDLAS-based tomography system was validated by using asymmetric premixed flames with fixed and time-varying equivalent ratios, respectively. The results demonstrate that the system is able to reconstruct the profiles of the 2D distributions of temperature and H{sub 2}O mole fraction of the flame and effectively capture the dynamics of the combustion process, which exhibits good potential for flame monitoring and on-line combustion diagnosis.« less

  19. Development of near infrared spectrometer for gem materials study

    NASA Astrophysics Data System (ADS)

    Jindata, W.; Meesiri, W.; Wongkokua, W.

    2015-07-01

    Most of gem materials can be characterized by infrared absorption spectroscopy. Normally, mid infrared absorption technique has been applied for investigating fundamental vibrational modes. However, for some gem materials, such as tourmaline, NIR is a better choice due to differentiation. Most commercial NIR spectrometers employ complicated dispersive grating or Fourier transform techniques. In this work, we developed a filter type NIR spectrometer with the availability of high efficiency and low-cost narrow bandpass NIR interference filters to be taught in a physics laboratory. The instrument was designed for transmission-mode configuration. A 50W halogen lamp was used as NIR source. There were fourteen NIR filters mounted on a rotatory wheel for wavelength selection ranging from 1000-1650 nm with steps of 50 nm. A 1.0 mm diameter of InGaAs photodiode was used as the detector for the spectrometer. Hence, transparent gem materials can be used as samples for experiment. Student can learn vibrational absorption spectroscopy as well as Beer-Lambert law from the development of this instrument.

  20. A new approach for the determination of sulphur in food samples by high-resolution continuum source flame atomic absorption spectrometer.

    PubMed

    Ozbek, N; Baysal, A

    2015-02-01

    The new approach for the determination of sulphur in foods was developed, and the sulphur concentrations of various fresh and dried food samples determined using a high-resolution continuum source flame atomic absorption spectrometer with an air/acetylene flame. The proposed method was optimised and the validated using standard reference materials, and certified values were found to be within the 95% confidence interval. The sulphur content of foods ranged from less than the LOD to 1.5mgg(-1). The method is accurate, fast, simple and sensitive. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Limiting Short-term Noise versus Optical Density in a Direct Absorption Spectrometer for Trace Gas Detection

    NASA Astrophysics Data System (ADS)

    Jervis, D.

    2016-12-01

    Field-deployable trace gas monitors are important for understanding a multitude of atmospheric processes: from forest photosynthesis and respiration [1], to fugitive methane emissions [2] and satellite measurement validation [3]. Consequently, a detailed knowledge of the performance limitations of these instruments is essential in order to establish reliable datasets. We present the short-term ( >1 Hz) performance of a long-pass direct absorption spectrometer as a function of the optical density of the absorption transition being probed. In particular, we identify fluctuations in the laser intensity as limiting the optical density uncertainty to 4x10-6/√Hz for weak transitions, and noise in the laser drive current as limiting the fractional noise in the optical density to 4x10-5/√Hz for deep transitions. We provide numerical and analytical predictions for both effects, as well as using the understanding of this phenomena to estimate how noise on neighboring strong and weak transitions couple to each other. All measurements were performed using the Aerodyne Research TILDAS Monitor, but are general to any instrument that uses direct absorption spectroscopy as a detection method. Wehr, R., et al. "Seasonality of temperate forest photosynthesis and daytime respiration." Nature 534.7609 (2016): 680-683. Conley, S., et al. "Methane emissions from the 2015 Aliso Canyon blowout in Los Angeles, CA." Science 351.6279 (2016): 1317-1320. Emmons, L. K., et al. "Validation of Measurements of Pollution in the Troposphere (MOPITT) CO retrievals with aircraft in situ profiles." Journal of Geophysical Research: Atmospheres 109.D3 (2004).

  2. High reflected cubic cavity as long path absorption cell for infrared gas sensing

    NASA Astrophysics Data System (ADS)

    Yu, Jia; Gao, Qiang; Zhang, Zhiguo

    2014-10-01

    One direct and efficient method to improve the sensitivity of infrared gas sensors is to increase the optical path length of gas cells according to Beer-Lambert Law. In this paper, cubic shaped cavities with high reflected inner coating as novel long path absorption cells for infrared gas sensing were developed. The effective optical path length (EOPL) for a single cubic cavity and tandem cubic cavities were investigated based on Tunable Diode Laser Absorption Spectroscopy (TDLAS) measuring oxygen P11 line at 763 nm. The law of EOPL of a diffuse cubic cavity in relation with the reflectivity of the coating, the port fraction and side length of the cavity was obtained. Experimental results manifested an increase of EOPL for tandem diffuse cubic cavities as the decrease of port fraction of the connecting aperture f', and the EOPL equaled to the sum of that of two single cubic cavities at f'<0.01. The EOPL spectra at infrared wavelength range for different inner coatings including high diffuse coatings and high reflected metallic thin film coatings were deduced.

  3. Low-cost lightweight airborne laser-based sensors for pipeline leak detection and reporting

    NASA Astrophysics Data System (ADS)

    Frish, Michael B.; Wainner, Richard T.; Laderer, Matthew C.; Allen, Mark G.; Rutherford, James; Wehnert, Paul; Dey, Sean; Gilchrist, John; Corbi, Ron; Picciaia, Daniele; Andreussi, Paolo; Furry, David

    2013-05-01

    Laser sensing enables aerial detection of natural gas pipeline leaks without need to fly through a hazardous gas plume. This paper describes adaptations of commercial laser-based methane sensing technology that provide relatively low-cost lightweight and battery-powered aerial leak sensors. The underlying technology is near-infrared Standoff Tunable Diode Laser Absorption Spectroscopy (sTDLAS). In one configuration, currently in commercial operation for pipeline surveillance, sTDLAS is combined with automated data reduction, alerting, navigation, and video imagery, integrated into a single-engine single-pilot light fixed-wing aircraft or helicopter platform. In a novel configuration for mapping landfill methane emissions, a miniaturized ultra-lightweight sTDLAS sensor flies aboard a small quad-rotor unmanned aerial vehicle (UAV).

  4. Field tests of a new, extractive, airborne 1.4 μm -TDLAS hygrometer (SEALDH-I) on a Learjet 35A

    NASA Astrophysics Data System (ADS)

    Buchholz, Bernhard; Ebert, Volker

    2013-04-01

    easier to validate the sensor function e.g. by a direct comparison with a primary water standard and to ensure traceability of the results to metrological standards. On the other hand it remains important to investigate sampling effects and artifacts in order to provide true measurements of the outside air. The SEALDH-I (Selective Extractive Airborne Laser Diode Hygrometer) is a new, absolute 1.37 μm Tunable Diode Laser Absorption Spectroscopy (TDLAS) hygrometer, which uses an advanced spectroscopic multiline fit and instrument stabilization process to enable a calibrations-free [1] evaluation of TDLAS signals [2]. SEALDHI is a compact (19" 4 HU), light weight (23 kg), fully extractive TDL hygrometer especially designed for space- and weight-limited airborne applications. It is based on an internal optical cell with 1.5 m optical path length. SEALDH-I's time resolution is limited by the flow through the cell: With an unpressurized inlet and gas handling system, we achieve with typical flows of 40 liter/min which leads to exchange times in the order of 0.5 sec. The laser scanning frequency of typically 140 Hz sets a maximum time resolution of 7 msec. Averaging data for about 2.1 sec ensures an excellent precision of 0.033 ppmv, which results in a band width and path length normalized precision of 72 ppbv?m?(Hz)-1-2. A dynamic range from 30 to 30000 ppmv has been proved and already validated in a blind intercomparison campaign [3]. The fast measurements, its excellent precision, validated accuracy, and absolute, calibration-free evaluation in combination with the compact, robust setup, allows airborne measurements from ground level up to the lower stratosphere. Furthermore SEALDH-I permits via its fast response time in combination with the large concentration range the resolution of fine atmospheric spatial structures and temporal fluctuations, particularly in clouds [4], where concentration gradients of 1000 ppmv per second can be present. We will present the result of

  5. A photoacoustic spectrometer for trace gas detection

    NASA Astrophysics Data System (ADS)

    Telles, E. M.; Bezerra, E.; Scalabrin, A.

    2005-06-01

    A high-resolution external laser photoacoustic spectrometer has been developed for trace gas detection with absorption transitions in coincidence with CO2 laser emission lines (9,2-10,9 μm: 920-1086 cm-1). The CO2 laser operates in 90 CW lines with power of up to 15 W. A PC-controlled step motor can tune the laser lines. The resonance frequency of first longitudinal mode of the photoacoustic cell is at 1600 Hz. The cell Q-factor and cell constant are measured close to 50 and 28 mVcmW-1, respectively. The spectrometer has been tested in preliminary studies to analyze the absorption transitions of ozone (O_3). The ethylene (C_2H_4) from papaya fruit is also investigated using N2 as carrier gas at a constant flow rate.

  6. Measurement of the spectral absorption of liquid water in melting snow with an imaging spectrometer

    NASA Technical Reports Server (NTRS)

    Green, Robert O.; Dozier, Jeff

    1995-01-01

    Melting of the snowpack is a critical parameter that drives aspects of the hydrology in regions of the earth where snow accumulates seasonally. New techniques for measurement of snow melt over regional scales offer the potential to improve monitoring and modeling of snow-driven hydrological processes. We present the results of measuring the spectral absorption of liquid water in a melting snowpack with the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). AVIRIS data were acquired over Mammoth Mountain, in east central California on 21 May 1994 at 18:35 UTC. The air temperature at 2926 m on Mammoth Mountain at site A was measured at 15-minute intervals during the day preceding the AVIRIS data acquisition. At this elevation, the air temperature did not drop below freezing the night of May 20 and had risen to 6 degrees Celsius by the time of the overflight on May 21. These temperature conditions support the presence of melting snow at the surface as the AVIRIS data were acquired.

  7. Spectrometer Baseline Control Via Spatial Filtering

    NASA Technical Reports Server (NTRS)

    Burleigh, M. R.; Richey, C. R.; Rinehart, S. A.; Quijada, M. A.; Wollack, E. J.

    2016-01-01

    An absorptive half-moon aperture mask is experimentally explored as a broad-bandwidth means of eliminating spurious spectral features arising from reprocessed radiation in an infrared Fourier transform spectrometer. In the presence of the spatial filter, an order of magnitude improvement in the fidelity of the spectrometer baseline is observed. The method is readily accommodated within the context of commonly employed instrument configurations and leads to a factor of two reduction in optical throughput. A detailed discussion of the underlying mechanism and limitations of the method are provided.

  8. Multilaser Herriott Cell for Planetary Tunable Laser Spectrometers

    NASA Technical Reports Server (NTRS)

    Tarsitano, Christopher G.; Webster, Christopher R.

    2007-01-01

    Geometric optics and matrix methods are used to mathematically model multilaser Herriott cells for tunable laser absorption spectrometers for planetary missions. The Herriott cells presented accommodate several laser sources that follow independent optical paths but probe a single gas cell. Strategically placed output holes located in the far mirrors of the Herriott cells reduce the size of the spectrometers. A four-channel Herriott cell configuration is presented for the specific application as the sample cell of the tunable laser spectrometer instrument selected for the sample analysis at Mars analytical suite on the 2009 Mars Science Laboratory mission.

  9. Uric acid detection using uv-vis spectrometer

    NASA Astrophysics Data System (ADS)

    Norazmi, N.; Rasad, Z. R. Abdul; Mohamad, M.; Manap, H.

    2017-10-01

    The aim of this research is to detect uric acid (UA) concentration using Ultraviolet-Visible (UV-Vis) spectrometer in the Ultraviolet (UV) region. Absorption technique was proposed to detect different uric acid concentrations and its UV absorption wavelength. Current practices commonly take a lot of times or require complicated structures for the detection process. By this proposed spectroscopic technique, every concentration can be detected and interpreted into an absorbance value at a constant wavelength peak in the UV region. This is due to the chemical characteristics belong to the uric acid since it has a particular absorption cross-section, σ which can be calculated using Beer’s Lambert law formula. The detection performance was displayed using Spectrasuite sofware. It showed fast time response about 3 seconds. The experiment proved that the concentrations of uric acid were successfully detected using UV-Vis spectrometer at a constant absorption UV wavelength, 294.46 nm in a low time response. Even by an artificial sample of uric acid, it successfully displayed a close value as the ones reported with the use of the medical sample. It is applicable in the medical field and can be implemented in the future for earlier detection of abnormal concentration of uric acid.

  10. Mid infrared MEMS FTIR spectrometer

    NASA Astrophysics Data System (ADS)

    Erfan, Mazen; Sabry, Yasser M.; Mortada, Bassem; Sharaf, Khaled; Khalil, Diaa

    2016-03-01

    In this work we report, for the first time to the best of our knowledge, a bulk-micromachined wideband MEMS-based spectrometer covering both the NIR and the MIR ranges and working from 1200 nm to 4800 nm. The core engine of the spectrometer is a scanning Michelson interferometer micro-fabricated using deep reactive ion etching (DRIE) technology. The spectrum is obtained using the Fourier Transform techniques that allows covering a very wide spectral range limited by the detector responsivity. The moving mirror of the interferometer is driven by a relatively large stroke electrostatic comb-drive actuator. Zirconium fluoride (ZrF4) multimode optical fibers are used to connect light between the white light source and the interferometer input, as well as the interferometer output to a PbSe photoconductive detector. The recorded signal-to-noise ratio is 25 dB at the wavelength of 3350 nm. The spectrometer is successfully used in measuring the absorption spectra of methylene chloride, quartz glass and polystyrene film. The presented solution provides a low cost method for producing miniaturized spectrometers in the near-/mid-infrared.

  11. 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.

  12. Oxygen measurement by multimode diode lasers employing gas correlation spectroscopy.

    PubMed

    Lou, Xiutao; Somesfalean, Gabriel; Chen, Bin; Zhang, Zhiguo

    2009-02-10

    Multimode diode laser (MDL)-based correlation spectroscopy (COSPEC) was used to measure oxygen in ambient air, thereby employing a diode laser (DL) having an emission spectrum that overlaps the oxygen absorption lines of the A band. A sensitivity of 700 ppm m was achieved with good accuracy (2%) and linearity (R(2)=0.999). For comparison, measurements of ambient oxygen were also performed by tunable DL absorption spectroscopy (TDLAS) technique employing a vertical cavity surface emitting laser. We demonstrate that, despite slightly degraded sensitivity, the MDL-based COSPEC-based oxygen sensor has the advantages of high stability, low cost, ease-of-use, and relaxed requirements in component selection and instrument buildup compared with the TDLAS-based instrument.

  13. Adaptive Tunable Laser Spectrometer for Space Applications

    NASA Technical Reports Server (NTRS)

    Flesch, Gregory; Keymeulen, Didier

    2010-01-01

    An architecture and process for the rapid prototyping and subsequent development of an adaptive tunable laser absorption spectrometer (TLS) are described. Our digital hardware/firmware/software platform is both reconfigurable at design time as well as autonomously adaptive in real-time for both post-integration and post-launch situations. The design expands the range of viable target environments and enhances tunable laser spectrometer performance in extreme and even unpredictable environments. Through rapid prototyping with a commercial RTOS/FPGA platform, we have implemented a fully operational tunable laser spectrometer (using a highly sensitive second harmonic technique). With this prototype, we have demonstrated autonomous real-time adaptivity in the lab with simulated extreme environments.

  14. Analysis of airborne imaging spectrometer data for the Ruby Mountains, Montana, by use of absorption-band-depth images

    NASA Technical Reports Server (NTRS)

    Brickey, David W.; Crowley, James K.; Rowan, Lawrence C.

    1987-01-01

    Airborne Imaging Spectrometer-1 (AIS-1) data were obtained for an area of amphibolite grade metamorphic rocks that have moderate rangeland vegetation cover. Although rock exposures are sparse and patchy at this site, soils are visible through the vegetation and typically comprise 20 to 30 percent of the surface area. Channel averaged low band depth images for diagnostic soil rock absorption bands. Sets of three such images were combined to produce color composite band depth images. This relative simple approach did not require extensive calibration efforts and was effective for discerning a number of spectrally distinctive rocks and soils, including soils having high talc concentrations. The results show that the high spectral and spatial resolution of AIS-1 and future sensors hold considerable promise for mapping mineral variations in soil, even in moderately vegetated areas.

  15. Measurement of the Spectral Absorption of Liquid Water in Melting Snow With an Imaging Spectrometer

    NASA Technical Reports Server (NTRS)

    Green, Robert O.; Dozier, Jeff

    1995-01-01

    Melting of the snowpack is a critical parameter that drives aspects of the hydrology in regions of the Earth where snow accumulates seasonally. New techniques for measurement of snow melt over regional scales offer the potential to improve monitoring and modeling of snow-driven hydrological processes. In this paper we present the results of measuring the spectral absorption of liquid water in a melting snowpack with the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). AVIRIS data were acquired over Mammoth Mountain, in east central California on 21 May 1994 at 18:35 UTC. The air temperature at 2926 m on Mammoth Mountain at site A was measured at 15-minute intervals during the day preceding the AVIRIS data acquisition. At this elevation. the air temperature did not drop below freezing the night of the May 20 and had risen to 6 degrees Celsius by the time of the overflight on May 21. These temperature conditions support the presence of melting snow at the surface as the AVIRIS data were acquired.

  16. Fast wavelength calibration method for spectrometers based on waveguide comb optical filter

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

    Yu, Zhengang; Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240; Huang, Meizhen, E-mail: mzhuang@sjtu.edu.cn

    2015-04-15

    A novel fast wavelength calibration method for spectrometers based on a standard spectrometer and a double metal-cladding waveguide comb optical filter (WCOF) is proposed and demonstrated. By using the WCOF device, a wide-spectrum beam is comb-filtered, which is very suitable for spectrometer wavelength calibration. The influence of waveguide filter’s structural parameters and the beam incident angle on the comb absorption peaks’ wavelength and its bandwidth are also discussed. The verification experiments were carried out in the wavelength range of 200–1100 nm with satisfactory results. Comparing with the traditional wavelength calibration method based on discrete sparse atomic emission or absorption lines,more » the new method has some advantages: sufficient calibration data, high accuracy, short calibration time, fit for produce process, stability, etc.« less

  17. Airborne interferometer for atmospheric emission and solar absorption.

    PubMed

    Keith, D W; Dykema, J A; Hu, H; Lapson, L; Anderson, J G

    2001-10-20

    The interferometer for emission and solar absorption (INTESA) is an infrared spectrometer designed to study radiative transfer in the troposphere and lower stratosphere from a NASA ER-2 aircraft. The Fourier-transform spectrometer (FTS) operates from 0.7 to 50 mum with a resolution of 0.7 cm(-1). The FTS observes atmospheric thermal emission from multiple angles above and below the aircraft. A heliostat permits measurement of solar absorption spectra. INTESA's calibration system includes three blackbodies to permit in-flight assessment of radiometric error. Results suggest that the in-flight radiometric accuracy is ~0.5 K in the mid-infrared.

  18. SEALDH-II—An Autonomous, Holistically Controlled, First Principles TDLAS Hygrometer for Field and Airborne Applications: Design–Setup–Accuracy/Stability Stress Test

    PubMed Central

    Buchholz, Bernhard; Kallweit, Sören; Ebert, Volker

    2016-01-01

    Instrument operation in harsh environments often significantly impacts the trust level of measurement data. While commercial instrument manufacturers clearly define the deployment conditions to achieve trustworthy data in typical standard applications, it is frequently unavoidable in scientific field applications to operate instruments outside these commercial standard application specifications. Scientific instrumentation, however, is employing cutting-edge technology and often highly optimized but also lacks long-term field tests to assess the field vs. laboratory performance. Recently, we developed the Selective Extractive Laser Diode Hygrometer (SEALDH-II), which addresses field and especially airborne applications as well as metrological laboratory validations. SEALDH-II targets reducing deviations between airborne hygrometers (currently up to 20% between the most advanced hygrometers) with a new holistic, internal control and validation concept, which guarantees the transfer of the laboratory performance into a field scenario by capturing more than 80 instrument internal “housekeeping” data to nearly perfectly control SEALDH-II’s health status. SEALDH-II uses a calibration-free, first principles based, direct Tuneable Diode Laser Absorption Spectroscopy (dTDLAS) approach, to cover the entire atmospheric humidity measurement range from about 3 to 40,000 ppmv with a calculated maximum uncertainty of 4.3% ± 3 ppmv. This is achieved not only by innovations in internal instrument monitoring and design, but also by active control algorithms such as a high resolution spectral stabilization. This paper describes the setup, working principles, and instrument stabilization, as well as its precision validation and long-term stress tests in an environmental chamber over an environmental temperature and humidity range of ΔT = 50 K and ΔRH = 80% RH, respectively. PMID:28042844

  19. SEALDH-II-An Autonomous, Holistically Controlled, First Principles TDLAS Hygrometer for Field and Airborne Applications: Design-Setup-Accuracy/Stability Stress Test.

    PubMed

    Buchholz, Bernhard; Kallweit, Sören; Ebert, Volker

    2016-12-30

    Instrument operation in harsh environments often significantly impacts the trust level of measurement data. While commercial instrument manufacturers clearly define the deployment conditions to achieve trustworthy data in typical standard applications, it is frequently unavoidable in scientific field applications to operate instruments outside these commercial standard application specifications. Scientific instrumentation, however, is employing cutting-edge technology and often highly optimized but also lacks long-term field tests to assess the field vs. laboratory performance. Recently, we developed the Selective Extractive Laser Diode Hygrometer (SEALDH-II), which addresses field and especially airborne applications as well as metrological laboratory validations. SEALDH-II targets reducing deviations between airborne hygrometers (currently up to 20% between the most advanced hygrometers) with a new holistic, internal control and validation concept, which guarantees the transfer of the laboratory performance into a field scenario by capturing more than 80 instrument internal "housekeeping" data to nearly perfectly control SEALDH-II's health status. SEALDH-II uses a calibration-free, first principles based, direct Tuneable Diode Laser Absorption Spectroscopy (dTDLAS) approach, to cover the entire atmospheric humidity measurement range from about 3 to 40,000 ppmv with a calculated maximum uncertainty of 4.3% ± 3 ppmv. This is achieved not only by innovations in internal instrument monitoring and design, but also by active control algorithms such as a high resolution spectral stabilization. This paper describes the setup, working principles, and instrument stabilization, as well as its precision validation and long-term stress tests in an environmental chamber over an environmental temperature and humidity range of ΔT = 50 K and ΔRH = 80% RH, respectively.

  20. Airborne tunable diode laser spectrometer for trace-gas measurement in the lower stratosphere

    NASA Technical Reports Server (NTRS)

    Podolske, James; Loewenstein, Max

    1993-01-01

    This paper describes the airborne tunable laser absorption spectrometer, a tunable diode laser instrument designed for in situ trace-gas measurement in the lower stratosphere from an ER-2 high-altitude research aircraft. Laser-wavelength modulation and second-harmonic detection are employed to achieve the required constituent detection sensitivity. The airborne tunable laser absorption spectrometer was used in two polar ozone campaigns, the Airborne Antarctic Ozone Experiment and the Airborne Arctic Stratospheric Expedition, and measured nitrous oxide with a response time of 1 s and an accuracy not greater than 10 percent.

  1. Superconducting gamma and fast-neutron spectrometers with high energy resolution

    DOEpatents

    Friedrich, Stephan; , Niedermayr, Thomas R.; Labov, Simon E.

    2008-11-04

    Superconducting Gamma-ray and fast-neutron spectrometers with very high energy resolution operated at very low temperatures are provided. The sensor consists of a bulk absorber and a superconducting thermometer weakly coupled to a cold reservoir, and determines the energy of the incident particle from the rise in temperature upon absorption. A superconducting film operated at the transition between its superconducting and its normal state is used as the thermometer, and sensor operation at reservoir temperatures around 0.1 K reduces thermal fluctuations and thus enables very high energy resolution. Depending on the choice of absorber material, the spectrometer can be configured either as a Gamma-spectrometer or as a fast-neutron spectrometer.

  2. Multiple-Diode-Laser Gas-Detection Spectrometer

    NASA Technical Reports Server (NTRS)

    Webster, Christopher R.; Beer, Reinhard; Sander, Stanley P.

    1988-01-01

    Small concentrations of selected gases measured automatically. Proposed multiple-laser-diode spectrometer part of system for measuring automatically concentrations of selected gases at part-per-billion level. Array of laser/photodetector pairs measure infrared absorption spectrum of atmosphere along probing laser beams. Adaptable to terrestrial uses as monitoring pollution or control of industrial processes.

  3. Rapid, optical measurement of the atmospheric pressure on a fast research aircraft using open-path TDLAS

    NASA Astrophysics Data System (ADS)

    Buchholz, B.; Afchine, A.; Ebert, V.

    2014-05-01

    Because of the high travel speed, the complex flow dynamics around an aircraft and the complex dependency of the fluid dynamics on numerous airborne parameters, it is quite difficult to obtain accurate pressure values at a specific instrument location of an aircraft's fuselage. Complex simulations using computational fluid dynamics (CFD) models can in theory computationally "transfer" pressure values from one location to another. However, for long flight patterns, this process is inconvenient and cumbersome. Furthermore these CFD transfer models require a local experimental validation, which is rarely available. In this paper, we describe an integrated approach for a spectroscopic, calibration-free, in-flight pressure determination in an open-path White cell on an aircraft fuselage using ambient, atmospheric water vapour as the "sensor species". The presented measurements are realized with the HAI (Hygrometer for Atmospheric Investigations) instrument, built for multiphase water detection via calibration-free TDLAS (tunable diode laser absorption spectroscopy). The pressure determination is based on raw data used for H2O concentration measurement, but with a different post-flight evaluation method, and can therefore be conducted at deferred time intervals on any desired flight track. The spectroscopic pressure is compared in-flight with the static ambient pressure of the aircraft avionic system and a micro-mechanical pressure sensor, located next to the open-path cell, over a pressure range from 150 hPa to 800 hPa, and a water vapour concentration range of more than three orders of magnitude. The correlation between the micro-mechanical pressure sensor measurements and the spectroscopic pressure measurements show an average deviation from linearity of only 0.14% and a small offset of 9.5 hPa. For the spectroscopic pressure evaluation we derive measurement uncertainties under laboratory conditions of 3.2% and 5.1% during in flight operation on the HALO airplane

  4. Rapid, optical measurement of the atmospheric pressure on a fast research aircraft using open-path TDLAS

    NASA Astrophysics Data System (ADS)

    Buchholz, B.; Afchine, A.; Ebert, V.

    2014-11-01

    Because of the high travel speed, the complex flow dynamics around an aircraft, and the complex dependency of the fluid dynamics on numerous airborne parameters, it is quite difficult to obtain accurate pressure values at a specific instrument location of an aircraft's fuselage. Complex simulations using computational fluid dynamics (CFD) models can in theory computationally "transfer" pressure values from one location to another. However, for long flight patterns, this process is inconvenient and cumbersome. Furthermore, these CFD transfer models require a local experimental validation, which is rarely available. In this paper, we describe an integrated approach for a spectroscopic, calibration-free, in-flight pressure determination in an open-path White cell on an aircraft fuselage using ambient, atmospheric water vapour as the "sensor species". The presented measurements are realised with the HAI (Hygrometer for Atmospheric Investigations) instrument, built for multiphase water detection via calibration-free TDLAS (tunable diode laser absorption spectroscopy). The pressure determination is based on raw data used for H2O concentration measurement, but with a different post-flight evaluation method, and can therefore be conducted at deferred time intervals on any desired flight track. The spectroscopic pressure is compared in-flight with the static ambient pressure of the aircraft avionic system and a micro-mechanical pressure sensor, located next to the open-path cell, over a pressure range from 150 to 800 hPa, and a water vapour concentration range of more than 3 orders of magnitude. The correlation between the micro-mechanical pressure sensor measurements and the spectroscopic pressure measurements shows an average deviation from linearity of only 0.14% and a small offset of 9.5 hPa. For the spectroscopic pressure evaluation we derive measurement uncertainties under laboratory conditions of 3.2 and 5.1% during in-flight operation on the HALO airplane. Under

  5. The temperature measurement research for high-speed flow based on tunable diode laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Di, Yue; Jin, Yi; Jiang, Hong-liang; Zhai, Chao

    2013-09-01

    Due to the particularity of the high-speed flow, in order to accurately obtain its' temperature, the measurement system should has some characteristics of not interfereing with the flow, non-contact measurement and high time resolution. The traditional measurement method cannot meet the above requirements, however the measurement method based on tunable diode laser absorption spectroscopy (TDLAS) technology can meet the requirements for high-speed flow temperature measurement. When the near-infared light of a specific frequency is through the media to be measured, it will be absorbed by the water vapor molecules and then the transmission light intensity is detected by the detector. The temperature of the water vapor which is also the high-speed flow temperature, can be accurately obtained by the Beer-Lambert law. This paper focused on the research of absorption spectrum method for high speed flow temperature measurement with the scope of 250K-500K. Firstly, spectral line selection method for low temperature measurement of high-speed flow is discussed. Selected absorption lines should be isolated and have a high peak absorption within the range of 250-500K, at the same time the interference of the other lines should be avoided, so that a high measurement accuracy can be obtained. According to the near-infrared absorption spectra characteristics of water vapor, four absorption lines at the near 1395 nm and 1409 nm are selected. Secondly, a system for the temperature measurement of the water vapor in the high-speed flow is established. Room temperature are measured through two methods, direct absorption spectroscopy (DAS) and wavelength modulation spectroscopy (WMS) ,the results show that this system can realize on-line measurement of the temperature and the measurement error is about 3%. Finally, the system will be used for temperature measurement of the high-speed flow in the shock tunnel, its feasibility of measurement is analyzed.

  6. Ultra-Wideband Optical Modulation Spectrometer (OMS) Development

    NASA Technical Reports Server (NTRS)

    Gardner, Jonathan (Technical Monitor); Tolls, Volker

    2004-01-01

    The optical modulation spectrometer (OMS) is a novel, highly efficient, low mass backend for heterodyne receiver systems. Current and future heterodyne receiver systems operating at frequencies up to a few THz require broadband spectrometer backends to achieve spectral resolutions of R approximately 10(exp 5) to 10(exp 6) to carry out many important astronomical investigations. Among these are observations of broad emission and absorption lines from extra-galactic objects at high redshifts, spectral line surveys, and observations of planetary atmospheres. Many of these lines are pressure or velocity broadened with either large half-widths or line wings extending over several GHz. Current backend systems can cover the needed bandwidth only by combining the output of several spectrometers, each with typically up to 1 GHz bandwidth, or by combining several frequency-shifted spectra taken with a single spectrometer. An ultra-wideband optical modulation spectrometer with 10 - 40 GHz bandwidth will enable broadband ob- servations without the limitations and disadvantages of hybrid spectrometers. Spectrometers like the OMS will be important for both ground-based observatories and future space missions like the Single Aperture Far-Infrared Telescope (SAFIR) which might carry IR/submm array heterodyne receiver systems requiring a spectrometer for each array pixel. Small size, low mass and small power consumption are extremely important for space missions. This report summarizes the specifications developed for the OMS and lists already identified commercial parts. The report starts with a review of the principle of operation, then describes the most important components and their specifications which were derived from theory, and finishes with a conclusion and outlook.

  7. Stratospheric ozone measurement with an infrared heterodyne spectrometer

    NASA Technical Reports Server (NTRS)

    Abbas, M. M.; Kostiuk, T.; Mumma, M. J.; Buhl, D.; Kunde, V. G.; Brown, L. W.

    1978-01-01

    Measurements of a stratospheric ozone concentration profile are made by detecting infrared absorption lines with a heterodyne spectrometer. The infrared spectrometer is based on a line-by-line tunable CO2 lasers, a liquid-nitrogen cooled HgCdTe photomixer, and a 64-channel spectral line receiver. The infrared radiation from the source is mixed with local-oscillator radiation. The difference frequency signal in a bandwidth above and below the local-oscillator frequency is detected. The intensity in each sideband is found by subtracting sideband contributions. It is found that absolute total column density is 0.32 plus or minus 0.02 cm-atm with a peak mixing ratio at about 24 km. The (7,1,6)-(7,1,7) O3 line center frequency is identified as 1043.1772/cm. Future work will involve a number of ozone absorption lines and measurements of diurnal variation. Completely resolved stratospheric lines may be inverted to yield concentration profiles of trace constituents and stratospheric gases.

  8. Glucose determination with fiber optic spectrometers

    NASA Astrophysics Data System (ADS)

    Starke, Eva; Kemper, Ulf; Barschdorff, Dieter

    1999-05-01

    Noninvasive blood glucose monitoring is the aim of research activities concerning the detection of small glucose concentrations dissolved in water and blood plasma. One approach for these measurements is the exploitation of absorption bands in the near infrared. However, the strong absorption of water represents a major difficulty. Transmission measurements of glucose dissolved in water and in blood plasma in the spectral region around 1600 nm with one- beam spectrometers and a FT-IR spectrometer are discussed. The evaluation of the data is carried out using a two-layer Lambert-Beer model and neural networks. In order to reduce the dimensions of a potential measuring device, an integrated acousto-optic tunable filter (AOTF) with an Erbium doped fiber amplifier as a radiation source is used. The fiber optic components are examined concerning their suitability. The smallest concentrations of glucose dissolved in water that can be separated are approximately 50 mg/dl. In the range of 50 mg/dl to 1000 mg/dl a correlation coefficient of 0.98 between real and estimated glucose concentrations is achieved using neural networks. In blood plasma so far glucose concentrations of about 100 mg/dl can be distinguished with good accuracy.

  9. Spatially Resolved Temperature and Water Vapor Concentration Distributions in Supersonic Combustion Facilities by TDLAT

    NASA Technical Reports Server (NTRS)

    Busa, K. M.; McDaniel J. C.; Diskin, G. S.; DePiro, M. J.; Capriotti, D. P.; Gaffney, R. L.

    2012-01-01

    Detailed knowledge of the internal structure of high-enthalpy flows can provide valuable insight to the performance of scramjet combustors. Tunable Diode Laser Absorption Spectroscopy (TDLAS) is often employed to measure temperature and species concentration. However, TDLAS is a path-integrated line-of-sight (LOS) measurement, and thus does not produce spatially resolved distributions. Tunable Diode Laser Absorption Tomography (TDLAT) is a non-intrusive measurement technique for determining two-dimensional spatially resolved distributions of temperature and species concentration in high enthalpy flows. TDLAT combines TDLAS with tomographic image reconstruction. More than 2500 separate line-of-sight TDLAS measurements are analyzed in order to produce highly resolved temperature and species concentration distributions. Measurements have been collected at the University of Virginia's Supersonic Combustion Facility (UVaSCF) as well as at the NASA Langley Direct-Connect Supersonic Combustion Test Facility (DCSCTF). Due to the UVaSCF s unique electrical heating and ability for vitiate addition, measurements collected at the UVaSCF are presented as a calibration of the technique. Measurements collected at the DCSCTF required significant modifications to system hardware and software designs due to its larger measurement area and shorter test duration. Tomographic temperature and water vapor concentration distributions are presented from experimentation on the UVaSCF operating at a high temperature non-reacting case for water vitiation level of 12%. Initial LOS measurements from the NASA Langley DCSCTF operating at an equivalence ratio of 0.5 are also presented. Results show the capability of TDLAT to adapt to several experimental setups and test parameters.

  10. Application of Internal Standard Method for Several 3d-Transition Metallic Elements in Flame Atomic Absorption Spectrometry Using a Multi-wavelength High-resolution Spectrometer.

    PubMed

    Toya, Yusuke; Itagaki, Toshiko; Wagatsuma, Kazuaki

    2017-01-01

    We investigated a simultaneous internal standard method in flame atomic absorption spectrometry (FAAS), in order to better the analytical precision of 3d-transition metals contained in steel materials. For this purpose, a new spectrometer system for FAAS, comprising a bright xenon lamp as the primary radiation source and a high-resolution Echelle monochromator, was employed to measure several absorption lines at a wavelength width of ca. 0.3 nm at the same time, which enables the absorbances of an analytical line and also an internal standard line to be estimated. In considering several criteria for selecting an internal standard element and the absorption line, it could be suggested that platinum-group elements: ruthenium, rhodium, or palladium, were suitable for an internal standard element to determine the 3d-transition metal elements, such as titanium, iron, and nickel, by measuring an appropriate pair of these absorption lines simultaneously. Several variances of the absorption signal, such as a variation in aspirated amounts of sample solution and a short-period drift of the primary light source, would be corrected and thus reduced, when the absorbance ratio of the analytical line to the internal standard line was measured. In Ti-Pd, Ni-Rh, and Fe-Ru systems chosen as typical test samples, the repeatability of the signal respnses was investigated with/without the internal standard method, resulting in better precision when the internal standard method was applied in the FAAS with a nitrous oxide-acetylene flame rather than an air-acetylene flame.

  11. 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.

  12. Toxic metals distribution in different components of Pakistani and imported cigarettes by electrothermal atomic absorption spectrometer.

    PubMed

    Kazi, T G; Jalbani, N; Arain, M B; Jamali, M K; Afridi, H I; Sarfraz, R A; Shah, A Q

    2009-04-15

    It was extensively investigated that a significant flux of toxic metals, along with other toxins, reaches the lungs through smoking. In present study toxic metals (TMs) (Al, Cd, Ni and Pb) were determined in different components of Pakistani local branded and imported cigarettes, including filler tobacco (FT), filter (before and after normal smoking by a single volunteer) and ash by electrothermal atomic absorption spectrometer (ETAAS). Microwave-assisted digestion method was employed. The validity and accuracy of methodology were checked by using certified sample of Virginia tobacco leaves (ICHTJ-cta-VTL-2). The percentages (%) of TMs in different components of cigarette were calculated with respect to their total contents in FT of all branded cigarettes before smoking, while smoke concentration has been calculated by subtracting the filter and ash contents from the filler tobacco content of each branded cigarette. The highest percentage (%) of Al was observed in ash of all cigarettes, with range 97.3-99.0%, while in the case of Cd, a reverse behaviour was observed, as a range of 15.0-31.3% of total contents were left in the ash of all branded cigarettes understudy.

  13. Galileo Ultraviolet Spectrometer experiment

    NASA Technical Reports Server (NTRS)

    Hord, C. W.; Mcclintock, W. E.; Stewart, A. I. F.; Barth, C. A.; Esposito, L. W.; Thomas, G. E.; Sandel, B. R.; Hunten, D. M.; Broadfoot, A. L.; Shemansky, D. E.

    1992-01-01

    The Galileo ultraviolet spectrometer experiment uses data obtained by the Ultraviolet Spectrometer (UVS) mounted on the pointed orbiter scan platform and from the Extreme Ultraviolet Spectrometer (EUVS) mounted on the spinning part of the orbiter with the field of view perpendicular to the spin axis. The UVS is a Ebert-Fastie design that covers the range 113-432 nm with a wavelength resolution of 0.7 nm below 190 and 1.3 nm at longer wavelengths. The UVS spatial resolution is 0.4 deg x 0.1 deg for illuminated disk observations and 1 deg x 0.1 deg for limb geometries. The EUVS is a Voyager design objective grating spectrometer, modified to cover the wavelength range from 54 to 128 nm with wavelength resolution 3.5 nm for extended sources and 1.5 nm for point sources and spatial resolution of 0.87 deg x 0.17 deg. The EUVS instrument will follow up on the many Voyager UVS discoveries, particularly the sulfur and oxygen ion emissions in the Io torus and molecular and atomic hydrogen auroral and airglow emissions from Jupiter. The UVS will obtain spectra of emission, absorption, and scattering features in the unexplored, by spacecraft, 170-432 nm wavelength region. The UVS and EUVS instruments will provide a powerful instrument complement to investigate volatile escape and surface composition of the Galilean satellites, the Io plasma torus, micro- and macro-properties of the Jupiter clouds, and the composition structure and evolution of the Jupiter upper atmosphere.

  14. High-performance dispersive Raman and absorption spectroscopy as tools for drug identification

    NASA Astrophysics Data System (ADS)

    Pawluczyk, Olga; Andrey, Sam; Nogas, Paul; Roy, Andrew; Pawluczyk, Romuald

    2009-02-01

    Due to increasing availability of pharmaceuticals from many sources, a need is growing to quickly and efficiently analyze substances in terms of the consistency and accuracy of their chemical composition. Differences in chemical composition occur at very low concentrations, so that highly sensitive analytical methods become crucial. Recent progress in dispersive spectroscopy with the use of 2-dimensional detector arrays, permits for signal integration along a long (up to 12 mm long) entrance slit of a spectrometer, thereby increasing signal to noise ratio and improving the ability to detect small concentration changes. This is achieved with a non-scanning, non-destructive system. Two different methods using P&P Optica high performance spectrometers were used. High performance optical dispersion Raman and high performance optical absorption spectroscopy were employed to differentiate various acetaminophen-containing drugs, such as Tylenol and other generic brands, which differ in their ingredients. A 785 nm excitation wavelength was used in Raman measurements and strong Raman signals were observed in the spectral range 300-1800 cm-1. Measurements with the absorption spectrometer were performed in the wavelength range 620-1020 nm. Both Raman and absorption techniques used transmission light spectrometers with volume phase holographic gratings and provided sufficient spectral differences, often structural, allowing for drug differentiation.

  15. Modular soft x-ray spectrometer for applications in energy sciences and quantum materials

    DOE PAGES

    Chuang, Yi -De; Shao, Yu -Cheng; Cruz, Alejandro; ...

    2017-01-27

    Over the past decade, the advances in grating-based soft X-ray spectrometers have revolutionized the soft X-ray spectroscopies in materials research. However, these novel spectrometers are mostly dedicated designs, which cannot be easily adopted for applications with diverging demands. Here we present a versatile spectrometer design concept based on the Hettrick-Underwood optical scheme that uses modular mechanical components. The spectrometer’s optics chamber can be used with gratings operated in either inside or outside orders, and the detector assembly can be reconfigured accordingly. The spectrometer can be designed to have high spectral resolution, exceeding 10 000 resolving power when using small sourcemore » (~1μm) and detector pixels (~5μm) with high line density gratings (~3000 lines/mm), or high throughput at moderate resolution. We report two such spectrometers with slightly different design goals and optical parameters in this paper. We show that the spectrometer with high throughput and large energy window is particularly useful for studying the sustainable energy materials. We demonstrate that the extensive resonant inelastic X-ray scattering (RIXS) map of battery cathode material LiNi 1/3Co 1/3Mn 1/3O 2 can be produced in few hours using such a spectrometer. Unlike analyzing only a handful of RIXS spectra taken at selected excitation photon energies across the elemental absorption edges to determine various spectral features like the localized dd excitations and non-resonant fluorescence emissions, these features can be easily identified in the RIXS maps. Studying such RIXS maps could reveal novel transition metal redox in battery compounds that are sometimes hard to be unambiguously identified in X-ray absorption and emission spectra. As a result, we propose that this modular spectrometer design can serve as the platform for further customization to meet specific scientific demands.« less

  16. Modular soft x-ray spectrometer for applications in energy sciences and quantum materials

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

    Chuang, Yi -De; Shao, Yu -Cheng; Cruz, Alejandro

    Over the past decade, the advances in grating-based soft X-ray spectrometers have revolutionized the soft X-ray spectroscopies in materials research. However, these novel spectrometers are mostly dedicated designs, which cannot be easily adopted for applications with diverging demands. Here we present a versatile spectrometer design concept based on the Hettrick-Underwood optical scheme that uses modular mechanical components. The spectrometer’s optics chamber can be used with gratings operated in either inside or outside orders, and the detector assembly can be reconfigured accordingly. The spectrometer can be designed to have high spectral resolution, exceeding 10 000 resolving power when using small sourcemore » (~1μm) and detector pixels (~5μm) with high line density gratings (~3000 lines/mm), or high throughput at moderate resolution. We report two such spectrometers with slightly different design goals and optical parameters in this paper. We show that the spectrometer with high throughput and large energy window is particularly useful for studying the sustainable energy materials. We demonstrate that the extensive resonant inelastic X-ray scattering (RIXS) map of battery cathode material LiNi 1/3Co 1/3Mn 1/3O 2 can be produced in few hours using such a spectrometer. Unlike analyzing only a handful of RIXS spectra taken at selected excitation photon energies across the elemental absorption edges to determine various spectral features like the localized dd excitations and non-resonant fluorescence emissions, these features can be easily identified in the RIXS maps. Studying such RIXS maps could reveal novel transition metal redox in battery compounds that are sometimes hard to be unambiguously identified in X-ray absorption and emission spectra. As a result, we propose that this modular spectrometer design can serve as the platform for further customization to meet specific scientific demands.« less

  17. Metrology for terahertz time-domain spectrometers

    NASA Astrophysics Data System (ADS)

    Molloy, John F.; Naftaly, Mira

    2015-12-01

    In recent years the terahertz time-domain spectrometer (THz TDS) [1] has emerged as a key measurement device for spectroscopic investigations in the frequency range of 0.1-5 THz. To date, almost every type of material has been studied using THz TDS, including semiconductors, ceramics, polymers, metal films, liquid crystals, glasses, pharmaceuticals, DNA molecules, proteins, gases, composites, foams, oils, and many others. Measurements with a TDS are made in the time domain; conversion from the time domain data to a frequency spectrum is achieved by applying the Fourier Transform, calculated numerically using the Fast Fourier Transform (FFT) algorithm. As in many other types of spectrometer, THz TDS requires that the sample data be referenced to similarly acquired data with no sample present. Unlike frequency-domain spectrometers which detect light intensity and measure absorption spectra, a TDS records both amplitude and phase information, and therefore yields both the absorption coefficient and the refractive index of the sample material. The analysis of the data from THz TDS relies on the assumptions that: a) the frequency scale is accurate; b) the measurement of THz field amplitude is linear; and c) that the presence of the sample does not affect the performance characteristics of the instrument. The frequency scale of a THz TDS is derived from the displacement of the delay line; via FFT, positioning errors may give rise to frequency errors that are difficult to quantify. The measurement of the field amplitude in a THz TDS is required to be linear with a dynamic range of the order of 10 000. And attention must be given to the sample positioning and handling in order to avoid sample-related errors.

  18. Absorption spectrometer balloon flight and iodine investigations

    NASA Technical Reports Server (NTRS)

    1970-01-01

    A high altitude balloon flight experiment to determine the technical feasibility of employing absorption spectroscopy to measure SO2 and NO2 gases in the earth's atmosphere from above the atmospheric ozone layer is discussed. In addition to the balloon experiment the contract includes a ground-based survey of natural I emissions from geological sources and studies of the feasibility of mapping I2 from spacecraft. This report is divided into three major sections as follows: (1) the planning engineering and execution of the balloon experiment, (2) data reduction and analysis of the balloon data, and (3) the results of the I2 phase of the contract.

  19. Hydrazine Detection with a Tunable Diode Laser Spectrometer

    NASA Technical Reports Server (NTRS)

    Houseman, John; Webster, C. R.; May, R. D.; Anderson, M. S.; Margolis, J. S.; Jackson, Julie R.; Brown, Pamela R.

    1999-01-01

    Several instruments have been developed to measure low concentrations of hydrazine but none completely meet the sensitivity requirements while satisfying additional criteria such as quick response, stable calibration, interference free operation, online operation, reasonable cost, etc. A brief review is presented of the current technology including the electrochemical cell, the ion mobility spectrometer, the mass spectrometer, and the gas chromatograph. A review of the advantages and disadvantages of these instruments are presented here. The review also includes commercially unavailable technology such as the electronic nose and the Tunable Diode Laser (TDL) IR Spectrometer. It was found that the TDL could meet the majority of these criteria including fast response, minimum maintenance, portability, and reasonable cost. An experiment was conducted to demonstrate the feasibility of such a system using an existing (non-portable) instrument. A lead-salt tunable diode laser, cooled to 85 degrees Kelvin was used to record direct absorption and second-derivative spectra of Hydrazine at several pressures to study the sensitivity to low levels of Hydrazine. Spectra of NH3 and CO2 were used for wavelength identification of the scanned region. With a pathlength of 80 m, detection sensitivities of about 1 ppb were achieved for hydrazine in dry nitrogen at a cell pressure of 100 mbar. For spectroscopic detection of Hydrazine, spectral regions including strong Ammonia or Carbon Dioxide lines must be avoided. Strong Hydrazine absorption features were identified at 940/cm showing minimal contribution from Ammonia interferences as suitable candidates for Hydrazine gas detection. For the studies reported here, the particular laser diode could only cover the narrow regions near 962/cm and 965/cm where strong Ammonia interferences were expected. However, the high resolution (0.001/cm) of the TDL spectrometer allowed individual lines of Hydrazine to be identified away from

  20. Ultraviolet absorption spectrum of HOCl

    NASA Technical Reports Server (NTRS)

    Burkholder, James B.

    1993-01-01

    The room temperature UV absorption spectrum of HOCl was measured over the wavelength range 200 to 380 nm with a diode array spectrometer. The absorption spectrum was identified from UV absorption spectra recorded following UV photolysis of equilibrium mixtures of Cl2O/H2O/HOCl. The HOCl spectrum is continuous with a maximum at 242 nm and a secondary peak at 304 nm. The measured absorption cross section at 242 nm was (2.1 +/- 0.3) x 10 exp -19/sq cm (2 sigma error limits). These results are in excellent agreement with the work of Knauth et al. (1979) but in poor agreement with the more recent measurements of Mishalanie et al. (1986) and Permien et al. (1988). An HOCl nu2 infrared band intensity of 230 +/- 35/sq cm atm was determined based on this UV absorption cross section. The present results are compared with these previous measurements and the discrepancies are discussed.

  1. The SPIRIT airborne instrument: a three-channel infrared absorption spectrometer with quantum cascade lasers for in situ atmospheric trace-gas measurements

    NASA Astrophysics Data System (ADS)

    Catoire, Valéry; Robert, Claude; Chartier, Michel; Jacquet, Patrick; Guimbaud, Christophe; Krysztofiak, Gisèle

    2017-09-01

    An infrared absorption spectrometer called SPIRIT (SPectromètre Infra-Rouge In situ Toute altitude) has been developed for airborne measurements of trace gases in the troposphere. At least three different trace gases can be measured simultaneously every 1.6 s using the coupling of a single Robert multipass optical cell with three Quantum Cascade Lasers (QCLs), easily interchangeable to select species depending on the scientific objectives. Absorptions of the mid-infrared radiations by the species in the cell at reduced pressure (<40 hPa), with path lengths adjustable up to 167.78 m, are quantified using an HgCdTe photodetector cooled by Stirling cycle. The performances of the instrument are assessed: a linearity with a coefficient of determination R 2 > 0.979 for the instrument response is found for CO, CH4, and NO2 volume mixing ratios under typical tropospheric conditions. In-flight comparisons with calibrated gas mixtures allow to show no instrumental drift correlated with atmospheric pressure and temperature changes (when vertical profiling) and to estimate the overall uncertainties in the measurements of CO, CH4, and NO2 to be 0.9, 22, and 0.5 ppbv, respectively. In-flight precision (1 σ) for these species at 1.6 s sampling is 0.3, 5, and 0.3 ppbv, respectively.

  2. Complex Resonance Absorption Structure in the X-Ray Spectrum of IRAS 13349+2438

    NASA Technical Reports Server (NTRS)

    Sako, M.; Kahn, S. M.; Behar, E.; Kaastra, J. S.; Brinkman, A. C.; Boller, Th.; Puchnarewicz, E. M.; Starling, R.; Liedahl, D. A.; Clavel, J.

    2000-01-01

    The luminous infrared-loud quasar IRAS 13349+2438 was observed with the XMM - Newton Observatory as part of the Performance Verification program. The spectrum obtained by the Reflection Grating Spectrometer (RGS) exhibits broad (FWHM - 1400 km/s) absorption lines from highly ionized elements including hydrogen- and helium-like carbon, nitrogen, oxygen, and neon, and several iron L - shell ions (Fe XVII - XX). Also shown in the spectrum is the first astrophysical detection of a broad absorption feature around lambda = 16 - 17 A identified as an unresolved transition array (UTA) of 2p - 3d inner-shell absorption by iron M-shell ions in a much cooler medium; a feature that might be misidentified as an O VII edge when observed with moderate resolution spectrometers. No absorption edges are clearly detected in the spectrum. We demonstrate that the RGS spectrum of IRAS 13349+2438 exhibits absorption lines from two distinct regions, one of which is tentatively associated with the medium that produces the optical/UV reddening.

  3. Short Pulse Laser Absorption and Energy Partition at Relativistic Laser Intensities

    NASA Astrophysics Data System (ADS)

    Ping, Yuan

    2005-10-01

    We present the first absorption measurements at laser intensity between 10^17 to 10^20 W/cm^2 using an intergrating sphere and a suite of diagnostics that measures scale length, hot electrons and laser harmonics. A much-enhanced absorption in the regime of relativestic electron heating was observed. Furthermore, we present measurements on the partitioning of absorbed laser energy into thermal and non-thermal electrons when illuminating solid targets from 10^17 to 10^19 W/cm^2. This was measured using a sub-picosecond x-ray streak camera interfaced to a dual crystal von H'amos crystal spectrograph, a spherical crystal x-ray imaging spectrometer, an electron spectrometer and optical spectrometer. Our data suggests an intensity dependent energy-coupling transition with greater energy portion into non-thermal electrons that rapidly transition to thermal electrons. The details of these experimental results and modeling simulations will be presented.

  4. Analysis of aircraft spectrometer data with logarithmic residuals

    NASA Technical Reports Server (NTRS)

    Green, A. A.; Craig, M. D.

    1985-01-01

    Spectra from airborne systems must be analyzed in terms of their mineral-related absorption features. Methods for removing backgrounds and extracting these features one at a time from reflectance spectra are discussed. Methods for converting radiance spectra into a form similar to reflectance spectra so that the feature extraction procedures can be implemented on aircraft spectrometer data are also discussed.

  5. A practical superconducting-microcalorimeter X-ray spectrometer for beamline and laboratory science

    DOE PAGES

    Doriese, W. B.; Abbamonte, P.; Alpert, B. K.; ...

    2017-05-01

    We describe a series of microcalorimeter X-ray spectrometers designed for a broad suite of measurement applications. The chief advantage of this type of spectrometer is that it can be orders of magnitude more efficient at collecting X-rays than more traditional high-resolution spectrometers that rely on wavelength-dispersive techniques. This advantage is most useful in applications that are traditionally photon-starved and/or involve radiation-sensitive samples. Each energy-dispersive spectrometer is built around an array of several hundred transition-edge sensors (TESs). TESs are superconducting thin films that are biased into their superconducting-to-normal-metal transitions. The spectrometers share a common readout architecture and many design elements, suchmore » as a compact, 65 mK detector package, 8-column time-division-multiplexed superconducting quantum-interference device readout, and a liquid-cryogen-free cryogenic system that is a two-stage adiabatic-demagnetization refrigerator backed by a pulse-tube cryocooler. We have adapted this flexible architecture to mate to a variety of sample chambers and measurement systems that encompass a range of observing geometries. There are two different types of TES pixels employed. The first, designed for X-ray energies below 10 keV, has a best demonstrated energy resolution of 2.1 eV (full-width-at-half-maximum or FWHM) at 5.9 keV. The second, designed for X-ray energies below 2 keV, has a best demonstrated resolution of 1.0 eV (FWHM) at 500 eV. Our team has now deployed seven of these X-ray spectrometers to a variety of light sources, accelerator facilities, and laboratory-scale experiments; these seven spectrometers have already performed measurements related to their applications. Another five of these spectrometers will come online in the near future. We have applied our TES spectrometers to the following measurement applications: synchrotron-based absorption and emission spectroscopy and energy

  6. A practical superconducting-microcalorimeter X-ray spectrometer for beamline and laboratory science

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

    Doriese, W. B.; Abbamonte, P.; Alpert, B. K.

    We describe a series of microcalorimeter X-ray spectrometers designed for a broad suite of measurement applications. The chief advantage of this type of spectrometer is that it can be orders of magnitude more efficient at collecting X-rays than more traditional high-resolution spectrometers that rely on wavelength-dispersive techniques. This advantage is most useful in applications that are traditionally photon-starved and/or involve radiation-sensitive samples. Each energy-dispersive spectrometer is built around an array of several hundred transition-edge sensors (TESs). TESs are superconducting thin films that are biased into their superconducting-to-normal-metal transitions. The spectrometers share a common readout architecture and many design elements, suchmore » as a compact, 65 mK detector package, 8-column time-division-multiplexed superconducting quantum-interference device readout, and a liquid-cryogen-free cryogenic system that is a two-stage adiabatic-demagnetization refrigerator backed by a pulse-tube cryocooler. We have adapted this flexible architecture to mate to a variety of sample chambers and measurement systems that encompass a range of observing geometries. There are two different types of TES pixels employed. The first, designed for X-ray energies below 10 keV, has a best demonstrated energy resolution of 2.1 eV (full-width-at-half-maximum or FWHM) at 5.9 keV. The second, designed for X-ray energies below 2 keV, has a best demonstrated resolution of 1.0 eV (FWHM) at 500 eV. Our team has now deployed seven of these X-ray spectrometers to a variety of light sources, accelerator facilities, and laboratory-scale experiments; these seven spectrometers have already performed measurements related to their applications. Another five of these spectrometers will come online in the near future. We have applied our TES spectrometers to the following measurement applications: synchrotron-based absorption and emission spectroscopy and energy

  7. A practical superconducting-microcalorimeter X-ray spectrometer for beamline and laboratory science

    NASA Astrophysics Data System (ADS)

    Doriese, W. B.; Abbamonte, P.; Alpert, B. K.; Bennett, D. A.; Denison, E. V.; Fang, Y.; Fischer, D. A.; Fitzgerald, C. P.; Fowler, J. W.; Gard, J. D.; Hays-Wehle, J. P.; Hilton, G. C.; Jaye, C.; McChesney, J. L.; Miaja-Avila, L.; Morgan, K. M.; Joe, Y. I.; O'Neil, G. C.; Reintsema, C. D.; Rodolakis, F.; Schmidt, D. R.; Tatsuno, H.; Uhlig, J.; Vale, L. R.; Ullom, J. N.; Swetz, D. S.

    2017-05-01

    We describe a series of microcalorimeter X-ray spectrometers designed for a broad suite of measurement applications. The chief advantage of this type of spectrometer is that it can be orders of magnitude more efficient at collecting X-rays than more traditional high-resolution spectrometers that rely on wavelength-dispersive techniques. This advantage is most useful in applications that are traditionally photon-starved and/or involve radiation-sensitive samples. Each energy-dispersive spectrometer is built around an array of several hundred transition-edge sensors (TESs). TESs are superconducting thin films that are biased into their superconducting-to-normal-metal transitions. The spectrometers share a common readout architecture and many design elements, such as a compact, 65 mK detector package, 8-column time-division-multiplexed superconducting quantum-interference device readout, and a liquid-cryogen-free cryogenic system that is a two-stage adiabatic-demagnetization refrigerator backed by a pulse-tube cryocooler. We have adapted this flexible architecture to mate to a variety of sample chambers and measurement systems that encompass a range of observing geometries. There are two different types of TES pixels employed. The first, designed for X-ray energies below 10 keV, has a best demonstrated energy resolution of 2.1 eV (full-width-at-half-maximum or FWHM) at 5.9 keV. The second, designed for X-ray energies below 2 keV, has a best demonstrated resolution of 1.0 eV (FWHM) at 500 eV. Our team has now deployed seven of these X-ray spectrometers to a variety of light sources, accelerator facilities, and laboratory-scale experiments; these seven spectrometers have already performed measurements related to their applications. Another five of these spectrometers will come online in the near future. We have applied our TES spectrometers to the following measurement applications: synchrotron-based absorption and emission spectroscopy and energy-resolved scattering

  8. A practical superconducting-microcalorimeter X-ray spectrometer for beamline and laboratory science.

    PubMed

    Doriese, W B; Abbamonte, P; Alpert, B K; Bennett, D A; Denison, E V; Fang, Y; Fischer, D A; Fitzgerald, C P; Fowler, J W; Gard, J D; Hays-Wehle, J P; Hilton, G C; Jaye, C; McChesney, J L; Miaja-Avila, L; Morgan, K M; Joe, Y I; O'Neil, G C; Reintsema, C D; Rodolakis, F; Schmidt, D R; Tatsuno, H; Uhlig, J; Vale, L R; Ullom, J N; Swetz, D S

    2017-05-01

    We describe a series of microcalorimeter X-ray spectrometers designed for a broad suite of measurement applications. The chief advantage of this type of spectrometer is that it can be orders of magnitude more efficient at collecting X-rays than more traditional high-resolution spectrometers that rely on wavelength-dispersive techniques. This advantage is most useful in applications that are traditionally photon-starved and/or involve radiation-sensitive samples. Each energy-dispersive spectrometer is built around an array of several hundred transition-edge sensors (TESs). TESs are superconducting thin films that are biased into their superconducting-to-normal-metal transitions. The spectrometers share a common readout architecture and many design elements, such as a compact, 65 mK detector package, 8-column time-division-multiplexed superconducting quantum-interference device readout, and a liquid-cryogen-free cryogenic system that is a two-stage adiabatic-demagnetization refrigerator backed by a pulse-tube cryocooler. We have adapted this flexible architecture to mate to a variety of sample chambers and measurement systems that encompass a range of observing geometries. There are two different types of TES pixels employed. The first, designed for X-ray energies below 10 keV, has a best demonstrated energy resolution of 2.1 eV (full-width-at-half-maximum or FWHM) at 5.9 keV. The second, designed for X-ray energies below 2 keV, has a best demonstrated resolution of 1.0 eV (FWHM) at 500 eV. Our team has now deployed seven of these X-ray spectrometers to a variety of light sources, accelerator facilities, and laboratory-scale experiments; these seven spectrometers have already performed measurements related to their applications. Another five of these spectrometers will come online in the near future. We have applied our TES spectrometers to the following measurement applications: synchrotron-based absorption and emission spectroscopy and energy-resolved scattering

  9. Measurements of stratospheric composition using a star pointing spectrometer

    NASA Technical Reports Server (NTRS)

    Fish, Deb J.; Jones, Rod L.; Freshwater, Ray A.; Roscoe, Howard K.; Oldham, Derek J.

    1994-01-01

    Measurements of stratospheric composition have been made with a novel star-pointing spectrometer. The instrument consists of a telescope that focuses light from stars, planets, or the moon onto a spectrometer and two dimensional CCD array detector. Atmospheric absorptions can be measured, from which atmospheric columns of several gases can be determined. The instrument was deployed in Abisko, 69 deg N, during the European Arctic Stratospheric Ozone Experiment (EASOE). The instrument has the potential for measuring O3, OClO, NO2, and NO3. In this paper, a method for the retrieval of vertical columns is described, and some examples of ozone measurements given.

  10. Method and apparatus for enhancing laser absorption sensitivity

    NASA Technical Reports Server (NTRS)

    Webster, Christopher R. (Inventor)

    1987-01-01

    A simple optomechanical method and apparatus is described for substantially reducing the amplitude of unwanted multiple interference fringes which often limit the sensitivities of tunable laser absorption spectrometers. An exterior cavity is defined by partially transmissible surfaces such as a laser exit plate, a detector input, etc. That cavity is spoiled by placing an oscillating plate in the laser beam. For tunable diode laser spectroscopy in the mid-infrared region, a Brewster-plate spoiler allows the harmonic detection of absorptances of less than 10 to the -5 in a single laser scan. Improved operation is achieved without subtraction techniques, without complex laser frequency modulation, and without distortion of the molecular lineshape signal. The technique is applicable to tunable lasers operating from UV to IR wavelengths and in spectrometers which employ either short or long pathlengths, including the use of retroreflectors or multipass cells.

  11. High sensitivity liquid phase measurements using broadband cavity enhanced absorption spectroscopy (BBCEAS) featuring a low cost webcam based prism spectrometer.

    PubMed

    Qu, Zhechao; Engstrom, Julia; Wong, Donald; Islam, Meez; Kaminski, Clemens F

    2013-11-07

    Cavity enhanced techniques enable high sensitivity absorption measurements in the liquid phase but are typically more complex, and much more expensive, to perform than conventional absorption methods. The latter attributes have so far prevented a wide spread use of these methods in the analytical sciences. In this study we demonstrate a novel BBCEAS instrument that is sensitive, yet simple and economical to set up and operate. We use a prism spectrometer with a low cost webcam as the detector in conjunction with an optical cavity consisting of two R = 0.99 dielectric mirrors and a white light LED source for illumination. High sensitivity liquid phase measurements were made on samples contained in 1 cm quartz cuvettes placed at normal incidence to the light beam in the optical cavity. The cavity enhancement factor (CEF) with water as the solvent was determined directly by phase shift cavity ring down spectroscopy (PS-CRDS) and also by calibration with Rhodamine 6G solutions. Both methods yielded closely matching CEF values of ~60. The minimum detectable change in absorption (αmin) was determined to be 6.5 × 10(-5) cm(-1) at 527 nm and was limited only by the 8 bit resolution of the particular webcam detector used, thus offering scope for further improvement. The instrument was used to make representative measurements on dye solutions and in the determination of nitrite concentrations in a variation of the widely used Griess Assay. Limits of detection (LOD) were ~850 pM for Rhodamine 6G and 3.7 nM for nitrite, respectively. The sensitivity of the instrument compares favourably with previous cavity based liquid phase studies whilst being achieved at a small fraction of the cost hitherto reported, thus opening the door to widespread use in the community. Further means of improving sensitivity are discussed in the paper.

  12. Design of a Film Cooling Experiment for Rocket Engines

    DTIC Science & Technology

    2010-03-01

    concentrations inside the UCC (22)............................................................ 25 Figure 7: PIV data in the UCC (23...64 Figure 38: UCC /FCR igniter ............................................................................................. 65 Figure 39: Ethylene...TDLAS Tunable Diode Laser Absorption Spectroscopy UCC Ultra Compact Combustor μm micrometers VI Virtual Instrument Xe Xenon ZnSe

  13. Detection of fatty product falsifications using a portable near infrared spectrometer

    NASA Astrophysics Data System (ADS)

    Kalinin, A. V.; Krasheninnikov, V. N.

    2017-01-01

    Spreading sales of counterfeited fatty-oil foods leads to a development of portable and operational analyzer of typical fatty acids (FA) which may be a near infrared (NIR) spectrometer. In this work the calibration models for prediction of named FA were built with the spectra of FT-NIR spectrometer for different absorption bands of the FA. The best parameters were obtained for the wavelength sub-band 1.0-1.8 μ, which includes the 2nd and 3rd overtones of C-H stretching vibrations (near 1.7 and 1.2 μ) and the combination band (1.42 μ). Applicability of the portable spectrometer based on linear NIR array photosensor for the quality analysis of spread, butter and fish oil by the typical FA has been tested.

  14. In situ ozone data for evaluation of the laser absorption spectrometer ozone remote sensor: 1979 southeastern Virginia urban plume study summer field program

    NASA Technical Reports Server (NTRS)

    Gregory, G. L.; Mcdougal, D. S.; Mathis, J. J., Jr.

    1980-01-01

    Ozone data from the 1979 Southeastern Virginia Urban Study (SEV-UPS) field program are presented. The SEV-UPS was conducted for evaluation of an ozone remote sensor, the Laser Absorption Spectrometer. During the measurement program, remote-sensor evaluation was in two areas; (1) determination of the remote sensor's accuracy, repeatability, and operational characteristics, and (2) demonstration of the application of remotely sensed ozone data in air-quality studies. Data from six experiments designed to provide in situ ozone data for evaluation of the sensor in area 1, above, are presented. Experiments consisted of overflights of a test area with the remote sensor aircraft while in situ measurements with a second aircraft and selected surface stations provided correlative ozone data within the viewing area of the remote sensor.

  15. Abatement of Perfluorinated Compounds Using Cylindrical Microwave Plasma Source at Low Pressure

    NASA Astrophysics Data System (ADS)

    Kim, Seong Bong; Park, S.; Park, Y.; Youn, S.; Yoo, S. J.

    2016-10-01

    Microwave plasma source with a cylindrical cavity has been proposed to abate the perfluorinated compounds (PFCs). This plasma source was designed to generate microwave plasma with the cylindrical shape and to be easily installed in existing exhaust line. The microwave frequency is 2.45 GHz and the operating pressure range is 0.1 Torr to 0.3 Torr. The plasma characteristic of the cylindrical microwave plasma source was measured using the optical spectrometer, and tunable diode laser absorption spectroscopy (TDLAS). The destruction and removal efficiency (DRE) of CF4 and CHF3 were measured by a quadrupole mass spectroscopy (QMS) with the various operation conditions. The effect of the addition of the oxygen gas were tested and also the correlation between the plasma parameters and the DRE are presented in this study. This work was supported by R&D Program of ``Plasma Advanced Technology for Agriculture and Food (Plasma Farming)'' through the National Fusion Research Institute of Korea (NFRI) funded by the Government funds.

  16. Analysis of algebraic reconstruction technique for accurate imaging of gas temperature and concentration based on tunable diode laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Hui-Hui, Xia; Rui-Feng, Kan; Jian-Guo, Liu; Zhen-Yu, Xu; Ya-Bai, He

    2016-06-01

    An improved algebraic reconstruction technique (ART) combined with tunable diode laser absorption spectroscopy(TDLAS) is presented in this paper for determining two-dimensional (2D) distribution of H2O concentration and temperature in a simulated combustion flame. This work aims to simulate the reconstruction of spectroscopic measurements by a multi-view parallel-beam scanning geometry and analyze the effects of projection rays on reconstruction accuracy. It finally proves that reconstruction quality dramatically increases with the number of projection rays increasing until more than 180 for 20 × 20 grid, and after that point, the number of projection rays has little influence on reconstruction accuracy. It is clear that the temperature reconstruction results are more accurate than the water vapor concentration obtained by the traditional concentration calculation method. In the present study an innovative way to reduce the error of concentration reconstruction and improve the reconstruction quality greatly is also proposed, and the capability of this new method is evaluated by using appropriate assessment parameters. By using this new approach, not only the concentration reconstruction accuracy is greatly improved, but also a suitable parallel-beam arrangement is put forward for high reconstruction accuracy and simplicity of experimental validation. Finally, a bimodal structure of the combustion region is assumed to demonstrate the robustness and universality of the proposed method. Numerical investigation indicates that the proposed TDLAS tomographic algorithm is capable of detecting accurate temperature and concentration profiles. This feasible formula for reconstruction research is expected to resolve several key issues in practical combustion devices. Project supported by the Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 61205151), the National Key Scientific Instrument and Equipment Development Project of China (Grant

  17. Study of high resolution x-ray spectrometer concepts for NIF experiments

    NASA Astrophysics Data System (ADS)

    Hill, K. W.; Bitter, M.; Delgado-Aparicio, L.; Efthimion, P.; Gao, L.; Maddox, J.; Pablant, N. A.; Beiersdorfer, P.; Chen, H.; Coppari, F.; Ma, T.; Nora, R.; Scott, H.; Schneider, M.; Mancini, R.

    2015-11-01

    Options have been investigated for DIM-insertable (Diagnostic Instrument Manipulator) high resolution (E/ ΔE ~ 3000 - 5000) Bragg crystal x-ray spectrometers for experiments on the NIF. Of interest are time integrated Cu K- and Ta L-edge absorption spectra and time resolved Kr He- β emission from compressed symcaps for inference of electron temperature from dielectronic satellites and electron density from Stark broadening. Cylindrical and conical von Hamos, Johann, and advanced high throughput designs have been studied. Predicted x-ray intensities, spectrometer throughputs, spectral resolution, and spatial focusing properties, as well as lab evaluations of some spectrometer candidates will be presented. Performed under the auspices of the US DOE by PPPL under contract DE-AC02-09CH11466 and by LLNL under contract DE-AC52-07NA27344.

  18. Photo-induced intersubband absorption in {Si}/{SiGe} quantum wells

    NASA Astrophysics Data System (ADS)

    Boucaud, P.; Gao, L.; Visocekas, F.; Moussa, Z.; Lourtioz, J.-M.; Julien, F. H.; Sagnes, I.; Campidelli, Y.; Badoz, P.-A.; Vagos, P.

    1995-12-01

    We have investigated photo-induced intersubband absorption in the valence band of {Si}/{SiGe} quantum wells. Carriers are optically generated in the quantum wells using an argon ion laser. The resulting infrared absorption is probed with a step-scan Fourier transform infrared spectrometer. The photo-induced infrared absorption in SiGe quantum wells is dominated by two contributions: the free carrier absorption, which is similar to bulk absorption in a uniformly doped SiGe layer, and the valence subband absorption in the quantum wells. Both p- and s-polarized intersubband absorptions are measured. We have observed that the photo-induced intersubband absorption in doped samples is shifted to lower energy as compared to direct intersubband absorption. This absorption process is attributed to carriers away from the Brillouin zone center. We show that the photo-induced technique is appropriate to study valence band mixing effects and their influence on intersubband absorption.

  19. Tracing Acetylene Dissolved in Transformer Oil by Tunable Diode Laser Absorption Spectrum.

    PubMed

    Ma, Guo-Ming; Zhao, Shu-Jing; Jiang, Jun; Song, Hong-Tu; Li, Cheng-Rong; Luo, Ying-Ting; Wu, Hao

    2017-11-02

    Dissolved gas analysis (DGA) is widely used in monitoring and diagnosing of power transformer, since the insulation material in the power transformer decomposes gases under abnormal operation condition. Among the gases, acetylene, as a symbol of low energy spark discharge and high energy electrical faults (arc discharge) of power transformer, is an important monitoring parameter. The current gas detection method used by the online DGA equipment suffers from problems such as cross sensitivity, electromagnetic compatibility and reliability. In this paper, an optical gas detection system based on TDLAS technology is proposed to detect acetylene dissolved in transformer oil. We selected a 1530.370 nm laser in the near infrared wavelength range to correspond to the absorption peak of acetylene, while using the wavelength modulation strategy and Herriott cell to improve the detection precision. Results show that the limit of detection reaches 0.49 ppm. The detection system responds quickly to changes of gas concentration and is easily to maintenance while has no electromagnetic interference, cross-sensitivity, or carrier gas. In addition, a complete detection process of the system takes only 8 minutes, implying a practical prospect of online monitoring technology.

  20. Gas Measurement Using Static Fourier Transform Infrared Spectrometers.

    PubMed

    Köhler, Michael H; Schardt, Michael; Rauscher, Markus S; Koch, Alexander W

    2017-11-13

    Online monitoring of gases in industrial processes is an ambitious task due to adverse conditions such as mechanical vibrations and temperature fluctuations. Whereas conventional Fourier transform infrared (FTIR) spectrometers use rather complex optical and mechanical designs to ensure stable operation, static FTIR spectrometers do not require moving parts and thus offer inherent stability at comparatively low costs. Therefore, we present a novel, compact gas measurement system using a static single-mirror Fourier transform spectrometer (sSMFTS). The system works in the mid-infrared range from 650 cm - 1 to 1250 cm - 1 and can be operated with a customized White cell, yielding optical path lengths of up to 120 cm for highly sensitive quantification of gas concentrations. To validate the system, we measure different concentrations of 1,1,1,2-Tetrafluoroethane (R134a) and perform a PLS regression analysis of the acquired infrared spectra. Thereby, the measured absorption spectra show good agreement with reference data. Since the system additionally permits measurement rates of up to 200 Hz and high signal-to-noise ratios, an application in process analysis appears promising.

  1. Gas Measurement Using Static Fourier Transform Infrared Spectrometers

    PubMed Central

    Schardt, Michael; Rauscher, Markus S.; Koch, Alexander W.

    2017-01-01

    Online monitoring of gases in industrial processes is an ambitious task due to adverse conditions such as mechanical vibrations and temperature fluctuations. Whereas conventional Fourier transform infrared (FTIR) spectrometers use rather complex optical and mechanical designs to ensure stable operation, static FTIR spectrometers do not require moving parts and thus offer inherent stability at comparatively low costs. Therefore, we present a novel, compact gas measurement system using a static single-mirror Fourier transform spectrometer (sSMFTS). The system works in the mid-infrared range from 650 cm−1 to 1250 cm−1 and can be operated with a customized White cell, yielding optical path lengths of up to 120 cm for highly sensitive quantification of gas concentrations. To validate the system, we measure different concentrations of 1,1,1,2-Tetrafluoroethane (R134a) and perform a PLS regression analysis of the acquired infrared spectra. Thereby, the measured absorption spectra show good agreement with reference data. Since the system additionally permits measurement rates of up to 200 Hz and high signal-to-noise ratios, an application in process analysis appears promising. PMID:29137193

  2. Pseudoslit Spectrometer

    NASA Technical Reports Server (NTRS)

    Reuter, Dennis C.; McCabe, George H.

    2004-01-01

    The pseudoslit spectrometer is a conceptual optoelectronic instrument that would offer some of the advantages, without the disadvantages, of prior linear-variable etalon (LVE) spectrometers and prior slit spectrometers. The pseudoslit spectrometer is so named because it would not include a slit, but the combined effects of its optical components would include a spatial filtering effect approximately equivalent to that of a slit. Like a prior LVE spectrometer, the pseudoslit spectrometer would include an LVE (essentially, a wedge-like narrowband- pass filter, the pass wavelength of which varies linearly with position in one dimension) in a focal plane covering an imaging planar array of photodetectors. However, the pseudoslit spectrometer would be more efficient because unlike a prior LVE spectrometer, the pseudoslit spectrometer would not have to be scanned across an entire field of view to obtain the spectrum of an object of interest that may occupy only a small portion of the field of view. Like a prior slit spectrometer, the pseudoslit spectrometer could acquire the entire spectrum of such a small object without need for scanning. However, the pseudoslit spectrometer would be optically and mechanically simpler: it would have fewer components and, hence, would pose less of a problem of alignment of components and would be less vulnerable to misalignment.

  3. Mid-infrared absorption spectroscopy using quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Haibach, Fred; Erlich, Adam; Deutsch, Erik

    2011-06-01

    Block Engineering has developed an absorption spectroscopy system based on widely tunable Quantum Cascade Lasers (QCL). The QCL spectrometer rapidly cycles through a user-selected range in the mid-infrared spectrum, between 6 to 12 μm (1667 to 833 cm-1), to detect and identify substances on surfaces based on their absorption characteristics from a standoff distance of up to 2 feet with an eye-safe laser. It can also analyze vapors and liquids in a single device. For military applications, the QCL spectrometer has demonstrated trace explosive, chemical warfare agent (CWA), and toxic industrial chemical (TIC) detection and analysis. The QCL's higher power density enables measurements from diffuse and highly absorbing materials and substrates. Other advantages over Fourier Transform Infrared (FTIR) spectroscopy include portability, ruggedness, rapid analysis, and the ability to function from a distance through free space or a fiber optic probe. This paper will discuss the basic technology behind the system and the empirical data on various safety and security applications.

  4. Open-path TDL-Spectrometry for a Tomographic Reconstruction of 2D H2O-Concentration Fields in the Soil-Air-Boundary-Layer of Permafrost

    NASA Astrophysics Data System (ADS)

    Seidel, Anne; Wagner, Steven; Dreizler, Andreas; Ebert, Volker

    2013-04-01

    The melting of permafrost soils in arctic regions is one of the effects of climate change. It is recognized that climatically relevant gases are emitted during the thawing process, and that they may lead to a positive atmospheric feedback [1]. For a better understanding of these developments, a quantification of the gases emitted from the soil would be required. Extractive sensors with local point-wise gas sampling are currently used for this task, but are hampered due to the complex spatial structure of the soil surface, which complicates the situation due to the essential need for finding a representative gas sampling point. For this situation it would be much preferred if a sensor for detecting 2D-concentration fields of e.g. water vapor, (and in the mid-term also for methane or carbon dioxide) directly in the soil-atmosphere-boundary layer of permafrost soils would be available. However, it also has to be kept in mind that field measurements over long time periods in such a harsh environment require very sturdy instrumentation preferably without the need for sensor calibration. Therefore we are currently developing a new, robust TDLAS (tuneable diode laser absorption spectroscopy)-spectrometer based on cheap reflective foils [2]. The spectrometer is easily transportable, requires hardly any alignment and consists of industrially available, very stable components (e.g. diode lasers and glass fibers). Our measurement technique, open path TDLAS, allows for calibration-free measurements of absolute H2O concentrations. The static instrument for sampling open-path H2O concentrations consists of a joint sending and receiving optics at one side of the measurement path and a reflective element at the other side. The latter is very easy to align, since it is a foil usually applied for traffic purposes that retro-reflects the light to its origin even for large angles of misalignment (up to 60°). With this instrument, we achieved normalized detection limits of up to 0

  5. A star-pointing UV-visible spectrometer for remote-sensing of the stratosphere

    NASA Technical Reports Server (NTRS)

    Roscoe, Howard K.; Freshwater, Ray A.; Jones, Rod L.; Fish, Debbie J.; Harries, John E.; Wolfenden, Roger; Stone, Phillip

    1994-01-01

    We have constructed a novel instrument for ground-based remote sensing, by mounting a UV-visible spectrometer on a telescope and observing the absorption by atmospheric constituents of light from stars. Potentially, the instrument can observe stratospheric O3, NO3, NO2, and OClO.

  6. VCSEL based Faraday rotation spectroscopy at 762nm for battery powered trace molecular oxygen detection

    NASA Astrophysics Data System (ADS)

    So, Stephen; Wysocki, Gerard

    2010-02-01

    Faraday Rotation Spectroscopy (FRS) is a polarization based spectroscopic technique which can provide higher sensitivity concentration measurements of paramagnetic gases and free radicals than direct absorption spectroscopic techniques. We have developed sensor systems which require only 0.2W to perform TDLAS (tunable diode laser absorption spectroscopy), and can additionally be quickly duty cycled, enabling operation in wireless sensor networks of laser-based trace gas sensors We adapted our integrated TDLAS electronics to perform FRS in a compact and more sensitive system for quantification of molecular oxygen (O2) using a 762.3nm VCSEL in the A band. Using an AC magnetic field, we demonstrate detector noise dominated performance, achieving 2.1×10-6/Hz1/2 equivalent detectable fractional absorption and a minimum detection limit of 462 ppmv O2 in 1 second in a 15cm path. At longer paths and integration times, such a sensor will enable oxygen measurements at biotic respiration levels (<1ppmv) to measure CO2 - O2 exchange for mapping natural exchange of greenhouse gases. Potential improvement of detection limits by increasing various system performance parameters is described.

  7. Method for the determination of cobalt from biological products with graphite furnace atomic absorption spectrometer

    NASA Astrophysics Data System (ADS)

    Zamfir, Oana-Liliana; Ionicǎ, Mihai; Caragea, Genica; Radu, Simona; Vlǎdescu, Marian

    2016-12-01

    Cobalt is a chemical element with symbol Co and atomic number 27 and atomic weight 58.93. 59 Co is the only stable cobalt isotope and the only isotope to exist naturally on Earth. Cobalt is the active center of coenzymes called cobalamin or cyanocobalamin the most common example of which is vitamin B12. Vitamin B12 deficiency can potentially cause severe and irreversible damage, especially to the brain and nervous system in the form of fatigue, depression and poor memory or even mania and psychosis. In order to study the degree of deficiency of the population with Co or the correctness of treatment with vitamin B12, a modern optoelectronic method for the determination of metals and metalloids from biological samples has been developed, Graphite Furnace - Atomic Absorption Spectrometer (GF- AAS) method is recommended. The technique is based on the fact that free atoms will absorb light at wavelengths characteristic of the element of interest. Free atoms of the chemical element can be produced from samples by the application of high temperatures. The system GF-AAS Varian used as biological samples, blood or urine that followed the digest of the organic matrix. For the investigations was used a high - performance GF-AAS with D2 - background correction system and a transversely heated graphite atomizer. As result of the use of the method are presented the concentration of Co in the blood or urine of a group of patient in Bucharest. The method is sensitive, reproducible relatively easy to apply, with a moderately costs.

  8. Effects of self-absorption on simultaneous estimation of temperature distribution and concentration fields of soot and metal-oxide nanoparticles in nanofluid fuel flames using a spectrometer

    NASA Astrophysics Data System (ADS)

    Liu, Guannan; Liu, Dong

    2018-06-01

    An improved inverse reconstruction model with consideration of self-absorption effect for the temperature distribution and concentration fields of soot and metal-oxide nanoparticles in nanofluid fuel flames was proposed based on the flame emission spectrometry. The effects of self-absorption on the temperature profile and concentration fields were investigated for various measurement errors, flame optical thicknesses and detecting lines numbers. The model neglecting the self-absorption caused serious reconstruction errors especially in the nanofluid fuel flames with large optical thicknesses, while the improved model was used to successfully recover the temperature distribution and concentration fields of soot and metal-oxide nanoparticles for the flames regardless of the optical thickness. Through increasing detecting lines number, the reconstruction accuracy can be greatly improved due to more flame emission information received by the spectrometer. With the adequate detecting lines number, the estimations for the temperature distribution and concentration fields of soot and metal-oxide nanoparticles in flames with large optical thicknesses were still satisfying even from the noisy radiation intensities with signal to noise ratio (SNR) as low as 46 dB. The results showed that the improved reconstruction model was effective and robust to concurrently retrieve the temperature distribution and volume fraction fields of soot and metal-oxide nanoparticles for the exact and noisy data in nanofluid fuel sooting flames with different optical thicknesses.

  9. Thomson Thick X-Ray Absorption in a Broad Absorption Line Quasar, PG 0946+301.

    PubMed

    Mathur; Green; Arav; Brotherton; Crenshaw; deKool; Elvis; Goodrich; Hamann; Hines; Kashyap; Korista; Peterson; Shields; Shlosman; van Breugel W; Voit

    2000-04-20

    We present a deep ASCA observation of a broad absorption line quasar (BALQSO) PG 0946+301. The source was clearly detected in one of the gas imaging spectrometers, but not in any other detector. If BALQSOs have intrinsic X-ray spectra similar to normal radio-quiet quasars, our observations imply that there is Thomson thick X-ray absorption (NH greater, similar1024 cm-2) toward PG 0946+301. This is the largest column density estimated so far toward a BALQSO. The absorber must be at least partially ionized and may be responsible for attenuation in the optical and UV. If the Thomson optical depth toward BALQSOs is close to 1, as inferred here, then spectroscopy in hard X-rays with large telescopes like XMM would be feasible.

  10. Surface reflectance retrieval from imaging spectrometer data using three atmospheric codes

    NASA Astrophysics Data System (ADS)

    Staenz, Karl; Williams, Daniel J.; Fedosejevs, Gunar; Teillet, Phil M.

    1994-12-01

    Surface reflectance retrieval from imaging spectrometer data has become important for quantitative information extraction in many application areas. In order to calculate surface reflectance from remotely measured radiance, radiative transfer codes play an important role for removal of the scattering and gaseous absorption effects of the atmosphere. The present study evaluates surface reflectances retrieved from airborne visible/infrared imaging spectrometer (AVIRIS) data using three radiative transfer codes: modified 5S (M5S), 6S, and MODTRAN2. Comparisons of the retrieved surface reflectance with ground-based reflectance were made for different target types such as asphalt, gravel, grass/soil mixture (soccer field), and water (Sooke Lake). The results indicate that the estimation of the atmospheric water vapor content is important for an accurate surface reflectance retrieval regardless of the radiative transfer code used. For the present atmospheric conditions, a difference of 0.1 in aerosol optical depth had little impact on the retrieved surface reflectance. The performance of MODTRAN2 is superior in the gas absorption regions compared to M5S and 6S.

  11. Total Absorption Study of Beta Decays Relevant for Nuclear Applications and Nuclear Structure

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

    Algora, A.; Valencia, E.; Tain, J. L.

    2014-06-01

    We present an overview of our activities related to the study of the beta decay of neutron rich nuclei relevant for nuclear applications. Recent results of the study of the beta decay of Br using a new segmented total absorption spectrometer are presented. Our measurements were performed at the IGISOL facility using trap-assisted total absorption spectroscopy.

  12. Beta-spectrometer with Si-detectors for the study of 144Ce-144Pr decays

    NASA Astrophysics Data System (ADS)

    Alexeev, I. E.; Bakhlanov, S. V.; Bazlov, N. V.; Chmel, E. A.; Derbin, A. V.; Drachnev, I. S.; Kotina, I. M.; Muratova, V. N.; Pilipenko, N. V.; Semyonov, D. A.; Unzhakov, E. V.; Yeremin, V. K.

    2018-05-01

    Here we present the specifications of a newly developed beta-spectrometer, based on full absorption Si(Li) detector and thin transmission detector, allowing one to perform efficient separation beta-radiation and accompanying X-rays and gamma radiation. Our method is based on registration of coincident events from both detectors. The spectrometer can be used for precision measurements of various beta-spectra, namely for the beta-spectrum shape study of 144Pr, which is considered to be an advantageous anti-neutrino source for sterile neutrino searches.

  13. 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

  14. Eddy covariance carbonyl sulphide flux measurements with a quantum cascade laser absorption spectrometer.

    PubMed

    Gerdel, Katharina; Spielmann, Felix Maximilian; Hammerle, Albin; Wohlfahrt, Georg

    2017-09-26

    The trace gas carbonyl sulphide (COS) has lately received growing interest in the eddy covariance (EC) community due to its potential to serve as an independent approach for constraining gross primary production and canopy stomatal conductance. Thanks to recent developments of fast-response high-precision trace gas analysers (e.g. quantum cascade laser absorption spectrometers (QCLAS)), a handful of EC COS flux measurements have been published since 2013. To date, however, a thorough methodological characterisation of QCLAS with regard to the requirements of the EC technique and the necessary processing steps has not been conducted. The objective of this study is to present a detailed characterization of the COS measurement with the Aerodyne QCLAS in the context of the EC technique, and to recommend best EC processing practices for those measurements. Data were collected from May to October 2015 at a temperate mountain grassland in Tyrol, Austria. Analysis of the Allan variance of high-frequency concentration measurements revealed sensor drift to occur under field conditions after an averaging time of around 50 s. We thus explored the use of two high-pass filtering approaches (linear detrending and recursive filtering) as opposed to block averaging and linear interpolation of regular background measurements for covariance computation. Experimental low-pass filtering correction factors were derived from a detailed cospectral analysis. The CO 2 and H 2 O flux measurements obtained with the QCLAS were compared against those obtained with a closed-path infrared gas analyser. Overall, our results suggest small, but systematic differences between the various high-pass filtering scenarios with regard to the fraction of data retained in the quality control and flux magnitudes. When COS and CO 2 fluxes are combined in the so-called ecosystem relative uptake rate, systematic differences between the high-pass filtering scenarios largely cancel out, suggesting that this

  15. Eddy covariance carbonyl sulphide flux measurements with a quantum cascade laser absorption spectrometer

    PubMed Central

    Gerdel, Katharina; Spielmann, Felix Maximilian; Hammerle, Albin; Wohlfahrt, Georg

    2017-01-01

    The trace gas carbonyl sulphide (COS) has lately received growing interest in the eddy covariance (EC) community due to its potential to serve as an independent approach for constraining gross primary production and canopy stomatal conductance. Thanks to recent developments of fast-response high-precision trace gas analysers (e.g. quantum cascade laser absorption spectrometers (QCLAS)), a handful of EC COS flux measurements have been published since 2013. To date, however, a thorough methodological characterisation of QCLAS with regard to the requirements of the EC technique and the necessary processing steps has not been conducted. The objective of this study is to present a detailed characterization of the COS measurement with the Aerodyne QCLAS in the context of the EC technique, and to recommend best EC processing practices for those measurements. Data were collected from May to October 2015 at a temperate mountain grassland in Tyrol, Austria. Analysis of the Allan variance of high-frequency concentration measurements revealed sensor drift to occur under field conditions after an averaging time of around 50 s. We thus explored the use of two high-pass filtering approaches (linear detrending and recursive filtering) as opposed to block averaging and linear interpolation of regular background measurements for covariance computation. Experimental low-pass filtering correction factors were derived from a detailed cospectral analysis. The CO2 and H2O flux measurements obtained with the QCLAS were compared against those obtained with a closed-path infrared gas analyser. Overall, our results suggest small, but systematic differences between the various high-pass filtering scenarios with regard to the fraction of data retained in the quality control and flux magnitudes. When COS and CO2 fluxes are combined in the so-called ecosystem relative uptake rate, systematic differences between the high-pass filtering scenarios largely cancel out, suggesting that this relative

  16. Eddy covariance carbonyl sulfide flux measurements with a quantum cascade laser absorption spectrometer

    NASA Astrophysics Data System (ADS)

    Gerdel, Katharina; Spielmann, Felix Maximilian; Hammerle, Albin; Wohlfahrt, Georg

    2017-09-01

    The trace gas carbonyl sulfide (COS) has lately received growing interest from the eddy covariance (EC) community due to its potential to serve as an independent approach for constraining gross primary production and canopy stomatal conductance. Thanks to recent developments of fast-response high-precision trace gas analysers (e.g. quantum cascade laser absorption spectrometers, QCLAS), a handful of EC COS flux measurements have been published since 2013. To date, however, a thorough methodological characterisation of QCLAS with regard to the requirements of the EC technique and the necessary processing steps has not been conducted. The objective of this study is to present a detailed characterisation of the COS measurement with the Aerodyne QCLAS in the context of the EC technique and to recommend best EC processing practices for those measurements. Data were collected from May to October 2015 at a temperate mountain grassland in Tyrol, Austria. Analysis of the Allan variance of high-frequency concentration measurements revealed the occurrence of sensor drift under field conditions after an averaging time of around 50 s. We thus explored the use of two high-pass filtering approaches (linear detrending and recursive filtering) as opposed to block averaging and linear interpolation of regular background measurements for covariance computation. Experimental low-pass filtering correction factors were derived from a detailed cospectral analysis. The CO2 and H2O flux measurements obtained with the QCLAS were compared with those obtained with a closed-path infrared gas analyser. Overall, our results suggest small, but systematic differences between the various high-pass filtering scenarios with regard to the fraction of data retained in the quality control and flux magnitudes. When COS and CO2 fluxes are combined in the ecosystem relative uptake rate, systematic differences between the high-pass filtering scenarios largely cancel out, suggesting that this relative metric

  17. Eddy covariance carbonyl sulfide flux measurements with a quantum cascade laser absorption spectrometer

    NASA Astrophysics Data System (ADS)

    Gerdel, Katharina; Spielmann, Felix M.; Hammerle, Albin; Wohlfahrt, Georg

    2016-04-01

    Carbonyl sulfide (COS) is the most abundant sulfur containing trace gas present in the troposphere at concentrations of around 500 ppt. Recent interest in COS by the ecosystem-physiological community has been sparked by the fact that COS co-diffuses into plant leaves pretty much the same way as carbon dioxide (CO2) does, but in contrast to CO2, COS is not known to be emitted by plants. Thus uptake of COS by vegetation has the potential to be used as a tracer for canopy gross photosynthesis, which cannot be measured directly, however represents a key term in the global carbon cycle. Since a few years, quantum cascade laser absorption spectrometers (QCLAS) are commercially available with the precision, sensitivity and time response suitable for eddy covariance (EC) flux measurements. While there exist a handful of published reports on EC flux measurements in the recent literature, no rigorous investigation of the applicability of QCLAS for EC COS flux measurements has been carried out so far, nor have been EC processing and QA/QC steps developed for carbon dioxide and water vapor flux measurements within FLUXNET been assessed for COS. The aim of this study is to close this knowledge gap, to discuss critical steps in the post-processing chain of COS EC flux measurements and to devise best-practice guidelines for COS EC flux data processing. To this end we collected EC COS (and CO2, H2O and CO) flux measurements above a temperate mountain grassland in Austria over the vegetation period 2015 with a commercially available QCLAS. We discuss various aspects of EC data post-processing, in particular issues with the time-lag estimation between sonic anemometer and QCLAS signals and QCLAS time series detrending, as well as QA/QC, in particular flux detection limits, random flux uncertainty, the interaction of various processing steps with common EC QA/QC filters (e.g. detrending and stationarity tests), u*-filtering, etc.

  18. Measurement of transient gas flow parameters by diode laser absorption spectroscopy

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

    Bolshov, M A; Kuritsyn, Yu A; Liger, V V

    2015-04-30

    An absorption spectrometer based on diode lasers is developed for measuring two-dimension maps of temperature and water vapour concentration distributions in the combustion zones of two mixing supersonic flows of fuel and oxidiser in the single run regime. The method of measuring parameters of hot combustion zones is based on detection of transient spectra of water vapour absorption. The design of the spectrometer considerably reduces the influence of water vapour absorption along the path of a sensing laser beam outside the burning chamber. The optical scheme is developed, capable of matching measurement results in different runs of mixture burning. Amore » new algorithm is suggested for obtaining information about the mixture temperature by constructing the correlation functions of the experimental spectrum with those simulated from databases. A two-dimensional map of temperature distribution in a test chamber is obtained for the first time under the conditions of plasma-induced combusion of the ethylene – air mixture. (laser applications and other topics in quantum electronics)« less

  19. Light extinction by Secondary Organic Aerosol: an intercomparison of three broadband cavity spectrometers

    NASA Astrophysics Data System (ADS)

    Varma, R. M.; Ball, S. M.; Brauers, T.; Dorn, H.-P.; Heitmann, U.; Jones, R. L.; Platt, U.; Pöhler, D.; Ruth, A. A.; Shillings, A. J. L.; Thieser, J.; Wahner, A.; Venables, D. S.

    2013-07-01

    Broadband optical cavity spectrometers are maturing as a technology for trace gas detection, but only recently have they been used to retrieve the extinction coefficient of aerosols. Sensitive broadband extinction measurements allow explicit separation of gas and particle phase spectral contributions, as well as continuous spectral measurements of aerosol extinction in favourable cases. In this work, we report an intercomparison study of the aerosol extinction coefficients measured by three such instruments: a broadband cavity ring-down spectrometer (BBCRDS), a cavity-enhanced differential optical absorption spectrometer (CE-DOAS), and an incoherent broadband cavity-enhanced absorption spectrometer (IBBCEAS). Experiments were carried out in the SAPHIR atmospheric simulation chamber as part of the NO3Comp campaign to compare the measurement capabilities of NO3 and N2O5 instrumentation. Aerosol extinction coefficients between 655 and 690 nm are reported for secondary organic aerosols (SOA) formed by the NO3 oxidation of β-pinene under dry and humid conditions. Despite different measurement approaches and spectral analysis procedures, the three instruments retrieved aerosol extinction coefficients that were in close agreement. The refractive index of SOA formed from the β-pinene + NO3 reaction was 1.61, and was not measurably affected by the chamber humidity or by aging of the aerosol over several hours. This refractive index is significantly larger than SOA refractive indices observed in other studies of OH and ozone-initiated terpene oxidations, and may be caused by the large proportion of organic nitrates in the particle phase. In an experiment involving ammonium sulphate particles the aerosol extinction coefficients as measured by IBBCEAS were found to be in reasonable agreement with those calculated using Mie theory. The results of the study demonstrate the potential of broadband cavity spectrometers for determining the optical properties of aerosols.

  20. Light extinction by secondary organic aerosol: an intercomparison of three broadband cavity spectrometers

    NASA Astrophysics Data System (ADS)

    Varma, R. M.; Ball, S. M.; Brauers, T.; Dorn, H.-P.; Heitmann, U.; Jones, R. L.; Platt, U.; Pöhler, D.; Ruth, A. A.; Shillings, A. J. L.; Thieser, J.; Wahner, A.; Venables, D. S.

    2013-11-01

    Broadband optical cavity spectrometers are maturing as a technology for trace-gas detection, but only recently have they been used to retrieve the extinction coefficient of aerosols. Sensitive broadband extinction measurements allow explicit separation of gas and particle phase spectral contributions, as well as continuous spectral measurements of aerosol extinction in favourable cases. In this work, we report an intercomparison study of the aerosol extinction coefficients measured by three such instruments: a broadband cavity ring-down spectrometer (BBCRDS), a cavity-enhanced differential optical absorption spectrometer (CE-DOAS), and an incoherent broadband cavity-enhanced absorption spectrometer (IBBCEAS). Experiments were carried out in the SAPHIR atmospheric simulation chamber as part of the NO3Comp campaign to compare the measurement capabilities of NO3 and N2O5 instrumentation. Aerosol extinction coefficients between 655 and 690 nm are reported for secondary organic aerosols (SOA) formed by the NO3 oxidation of β-pinene under dry and humid conditions. Despite different measurement approaches and spectral analysis procedures, the three instruments retrieved aerosol extinction coefficients that were in close agreement. The refractive index of SOA formed from the β-pinene + NO3 reaction was 1.61, and was not measurably affected by the chamber humidity or by aging of the aerosol over several hours. This refractive index is significantly larger than SOA refractive indices observed in other studies of OH and ozone-initiated terpene oxidations, and may be caused by the large proportion of organic nitrates in the particle phase. In an experiment involving ammonium sulfate particles, the aerosol extinction coefficients as measured by IBBCEAS were found to be in reasonable agreement with those calculated using the Mie theory. The results of the study demonstrate the potential of broadband cavity spectrometers for determining the optical properties of aerosols.

  1. A Simple, Student-Built Spectrometer to Explore Infrared Radiation and Greenhouse Gases

    ERIC Educational Resources Information Center

    Bruce, Mitchell R. M.; Wilson, Tiffany A.; Bruce, Alice E.; Bessey, S. Max; Flood, Virginia J.

    2016-01-01

    In this experiment, students build a spectrometer to explore infrared radiation and greenhouse gases in an inquiry-based investigation to introduce climate science in a general chemistry lab course. The lab is based on the exploration of the thermal effects of molecular absorption of infrared radiation by greenhouse and non-greenhouse gases. A…

  2. Cavity ring-down spectroscopy of Doppler-broadened absorption line with sub-MHz absolute frequency accuracy.

    PubMed

    Cheng, C-F; Sun, Y R; Pan, H; Lu, Y; Li, X-F; Wang, J; Liu, A-W; Hu, S-M

    2012-04-23

    A continuous-wave cavity ring-down spectrometer has been built for precise determination of absolute frequencies of Doppler-broadened absorption lines. Using a thermo-stabilized Fabry-Pérot interferometer and Rb frequency references at the 780 nm and 795 nm, 0.1 - 0.6 MHz absolute frequency accuracy has been achieved in the 775-800 nm region. A water absorption line at 12579 cm(-1) is studied to test the performance of the spectrometer. The line position at zero-pressure limit is determined with an uncertainty of 0.3 MHz (relative accuracy of 0.8 × 10(-9)). © 2012 Optical Society of America

  3. Passive Ranging Using a Dispersive Spectrometer and Optical Filters

    DTIC Science & Technology

    2012-12-20

    transform spectrometers. These in- struments are very sensitive to vibration, however, making them difficult to use on an air or space-borne platform. This... techniques will scale to longer ranges. An instrument using filters is predicted to be more accurate at long ranges, but only if the grating...done by Leonpacher at AFIT. This research focused on the CO2 absorption feature at 4.3 µm. His technique compared the relative intensity between two

  4. Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) spectrometer design and performance

    NASA Technical Reports Server (NTRS)

    Macenka, Steven A.; Chrisp, Michael P.

    1987-01-01

    The development of the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) has been completed at JPL. This paper outlines the functional requirements of the spectrometer optics subsystem, and describes the spectrometer optical design. The optical subsystem performance is shown in terms of spectral modulation transfer functions, radial energy distributions, and system transmission at selected wavelengths for the four spectrometers. An outline of the spectrometer alignment is included.

  5. Real Time Diagnostics of Jet Engine Exhaust Plumes Using a Chirped QC Laser Spectrometer

    NASA Astrophysics Data System (ADS)

    Hay, K. G.; Duxbury, G.; Langford, N.

    2010-06-01

    Quantitative measurements of real-time variations of the chemical composition of a jet engine exhaust plume is demonstrated using a 4.86 μmn intra-pulse quantum cascade laser spectrometer. The measurements of the gas turbine exhaust were carried out in collaboration with John Black and Mark Johnson at Rolls Royce. The recording of five sets of averaged spectra a second has allowed us to follow the build up of the combustion products within the exhaust, and to demonstrate the large variation of the integrated absorption of these absorption lines with temperature. The absorption cross sections of the lines of both carbon monoxide and water increase with temperature, whereas those of the three main absorption lines of carbon dioxide decrease. At the steady state limit the absorption lines of carbon dioxide are barely visible, and the spectrum is dominated by absorption lines of carbon monoxide and water.

  6. Capillary Absorption Spectrometer for 13C Isotopic Composition of Pico to Subpico Molar Sample Quantities

    NASA Astrophysics Data System (ADS)

    Moran, J.; Kelly, J.; Sams, R.; Newburn, M.; Kreuzer, H.; Alexander, M.

    2011-12-01

    Quick incorporation of IR spectroscopy based isotope measurements into cutting edge research in biogeochemical cycling attests to the advantages of a spectroscopy versus mass spectrometry method for making some 13C measurements. The simple principles of optical spectroscopy allow field portability and provide a more robust general platform for isotope measurements. We present results with a new capillary absorption spectrometer (CAS) with the capability of reducing the sample size required for high precision isotopic measurements to the picomolar level and potentially the sub-picomolar level. This work was motivated by the minute sample size requirements for laser ablation isotopic studies of carbon cycling in microbial communities but has potential to be a valuable tool in other areas of biological and geological research. The CAS instrument utilizes a capillary waveguide as a sample chamber for interrogating CO2 via near IR laser absorption spectroscopy. The capillary's small volume (~ 0.5 mL) combined with propagation and interaction of the laser mode with the entire sample reduces sample size requirements to a fraction of that accessible with commercially available IR absorption including those with multi-pass or ring-down cavity systems. Using a continuous quantum cascade laser system to probe nearly adjacent rovibrational transitions of different isotopologues of CO2 near 2307 cm-1 permits sample measurement at low analyte pressures (as low as 2 Torr) for further sensitivity improvement. A novel method to reduce cw-fringing noise in the hollow waveguide is presented, which allows weak absorbance features to be studied at the few ppm level after averaging 1,000 scans in 10 seconds. Detection limits down to the 20 picomoles have been observed, a concentration of approximately 400 ppm at 2 Torr in the waveguide with precision and accuracy at or better than 1 %. Improvements in detection and signal averaging electronics and laser power and mode quality are

  7. Development of high resolution x-ray spectrometers for the investigation of bioinorganic chemistry in metalloproteins

    NASA Astrophysics Data System (ADS)

    Drury, Owen Byron

    We have built an X-ray spectrometer for synchrotron-based high-resolution soft X-ray spectroscopy. The spectrometer uses four 9-pixel arrays of superconducting tunnel junctions (STJs) as sensors. They infer the energy of an absorbed X-ray from a temporary increase in tunneling current. The STJs are operated in a two-stage adiabatic demagnetization refrigerator (ADR) that uses liquid nitrogen and helium for precooling to 77 K and 4.2 K, and gallium gadolinium garnet and iron ammonium sulfate to attain a base temperature below 0.1 K. The sensors are held at the end of a 40-cm-long cold finger within ˜1 cm of a sample located inside the vacuum chamber of a synchrotron beam line end station. The spectrometer has an energy resolution between 10 eV and 20 eV FWHM below 1 keV, can be operated at rates up to ˜106 counts/s. STJ spectrometers are suited for chemical analysis of dilute samples by fluorescence-detected X-ray absorption spectroscopy (XAS) in cases where conventional germanium detectors do not have enough energy resolution. We have used this STJ spectrometer at the Advanced Light Source synchrotron for spectroscopy on the lower energy X-ray absorption edges of the elements Mo, S, Fe and N. These elements play an important role in biological nitrogen fixation at the metalloprotein nitrogenase, and we have examined if STJ spectrometers can be used to provide new insights into some of the open questions regarding the reaction mechanism of this protein. We have taken X-ray absorption near-edge spectra (XANES) and extended fine structure spectra (EXAFS) of an Fe 6N(CO)15-compound containing a single N atom inside a cluster of six Fe atoms, as postulated to exist inside the Fe-S cluster of the FeMo-cofactor (FeMo-co) in nitrogenase. The STJ detector has enabled the first-ever extended range EXAFS scans on nitrogen through the oxygen K-edge, enabling a comparison with N EXAFS on FeMo-co. We have taken iron L23-edge spectra of the Fe-S cluster in FeMo-co, which can be

  8. Tunable Diode Laser Absorption Spectroscopy Verification Analysis for Use in the Combustion Optimization and Analysis Laser Laboratory

    DTIC Science & Technology

    2009-03-01

    characterized experimental data by operating the system over a wide range of conditions for an H2 laminar flame produced by a Hencken burner. The TDLAS...43 3.3 Combustion System Calibration and Operation ................................... 47 3.3.1 Theoretical...51 3.3.3 Hencken Burner Operation ............................................................... 56 3.3.4 Turbulent Jet Operation

  9. Brewster-plate spoiler - A novel method for reducing the amplitude of interference fringes that limit tunable-laser absorption sensitivities

    NASA Technical Reports Server (NTRS)

    Webster, C. R.

    1985-01-01

    A simple method is described for substantially reducing the amplitude of interference fringes that limit the sensitivities of tunable-laser high-resolution absorption spectrometers. A lead-salt diode laser operating in the 7-micron region is used with a single Brewster-plate spoiler to reduce the fringe amplitude by a factor of 30 and also to allow the detection of absorptances 0.001 percent in a single laser scan without subtraction techniques, without complex frequency modulation, and without distortion of the molecular line-shape signals. Application to multipass-cell spectrometers is described.

  10. Temperature dependence of the ClONO2 UV absorption spectrum

    NASA Technical Reports Server (NTRS)

    Burkholder, James B.; Talukdar, Ranajit K.; Ravishankara, A. R.

    1994-01-01

    The temperature dependence of the ClONO2 absorption spectrum has been measured between 220 and 298 K and between 195 and 430 nm using a diode array spectrometer. The absorption cross sections were determined using both: (1) absolute pressure measurements at 296 K and (2) measurements at various temperatures relative to 296 K using a dual absorption cell arrangement. The temperature dependence of the ClONO2 absorption spectrum shows very broad structure. The amplitude of the temperature dependence relative to that at 296 K is weak at short wavelengths, less than 2% at 215 nm and 220 K, but significant at the wavelengths important in the stratosphere, about 30% at 325 nm and 220 K. Our ClONO2 absorption cross section data are in good general agreement with the previous measurements of Molina and Molina (1979).

  11. Rugged TDLAS system for High Energy Laser atmospheric propagation characterization

    NASA Astrophysics Data System (ADS)

    Perram, Glen; Rice, Christopher

    2008-10-01

    An active remote sensing instrument for the characterization of atmospheric absorption, scattering, and scintillation at several key high energy laser wavelengths is in development. The instrument is based on narrow band tunable diode lasers fiber coupled to a 12'' Ritchey-Chretien transmit telescope and a second receive telescope with visible or near infrared imager. For example, tunable diode lasers have been used to obtain absorption spectra in the laboratory for the Cs D2 lines near 852 nm and the oxygen X-b lines near 760 nm, key to the Diode Pumped Alkali Laser (DPAL) concept. Absorbencies of less than 0.5% are observable. Applications will be assessed including effects to HEL atmospheric propagation from molecular and aerosol absorption and scattering, Cn2 estimation from atmospheric turbulence, hazardous chemical emission detection, and laser communication interception from side scattering. The system will soon be deployed to a military laser test range to characterize path lengths of greater than 1 km.

  12. Design of an FT-NIR spectrometer for online quality analysis of traditional Chinese medicine manufacturing process

    NASA Astrophysics Data System (ADS)

    Zhu, Ren; Wu, Lan; Wang, Shiming; Ye, Linhua; Ding, Zhihua

    2008-03-01

    As a fast, non-destructive analysis method, Fourier transform (FT) near-infrared (NIR) spectroscopy is very suitable and effective for online quality analysis of traditional Chinese medicine (TCM) manufacturing process. In this thesis, the theoretics of FT-NIRS was analyzed and an FT-NIR spectrometer with 4 cm -1 resolution in the 12500-5000 cm -1 frequency range was designed. The spectrometer was based on a Michelson interferometer with Bromine tungsten lamp as the NIR light source and InGaAs detector to collect the interference signal. Each element was designed and chosen to provide maximum sensitivity in the NIR spectral region. A fiber-optic flow cell system was used to realize online analysis of traditional Chinese medicine. The performance of the spectrometer was evaluated and the feasibility of using FT-NIR spectrometer to get absorption spectra of traditional Chinese medicine was demonstrated.

  13. Spherical grating spectrometers

    NASA Astrophysics Data System (ADS)

    O'Donoghue, Darragh; Clemens, J. Christopher

    2014-07-01

    We describe designs for spectrometers employing convex dispersers. The Offner spectrometer was the first such instrument; it has almost exclusively been employed on satellite platforms, and has had little impact on ground-based instruments. We have learned how to fabricate curved Volume Phase Holographic (VPH) gratings and, in contrast to the planar gratings of traditional spectrometers, describe how such devices can be used in optical/infrared spectrometers designed specifically for curved diffraction gratings. Volume Phase Holographic gratings are highly efficient compared to conventional surface relief gratings; they have become the disperser of choice in optical / NIR spectrometers. The advantage of spectrometers with curved VPH dispersers is the very small number of optical elements used (the simplest comprising a grating and a spherical mirror), as well as illumination of mirrors off axis, resulting in greater efficiency and reduction in size. We describe a "Half Offner" spectrometer, an even simpler version of the Offner spectrometer. We present an entirely novel design, the Spherical Transmission Grating Spectrometer (STGS), and discuss exemplary applications, including a design for a double-beam spectrometer without any requirement for a dichroic. This paradigm change in spectrometer design offers an alternative to all-refractive astronomical spectrometer designs, using expensive, fragile lens elements fabricated from CaF2 or even more exotic materials. The unobscured mirror layout avoids a major drawback of the previous generation of catadioptric spectrometer designs. We describe laboratory measurements of the efficiency and image quality of a curved VPH grating in a STGS design, demonstrating, simultaneously, efficiency comparable to planar VPH gratings along with good image quality. The stage is now set for construction of a prototype instrument with impressive performance.

  14. MMI-based MOEMS FT spectrometer for visible and IR spectral ranges

    NASA Astrophysics Data System (ADS)

    Al-Demerdash, Bassem M.; Medhat, Mostafa; Sabry, Yasser M.; Saadany, Bassam; Khalil, Diaa

    2014-03-01

    MEMS spectrometers have very strong potential in future healthcare and environmental monitoring applications, where Michelson interferometers are the core optical engine. Recently, MEMS Michelson interferometers based on using silicon interface as a beam splitter (BS) has been proposed [7, 8]. This allows having a monolithically-integrated on-chip FTIR spectrometer. However silicon BS exhibits high absorption loss in the visible range and high material dispersion in the near infrared (NIR) range. For this reason, we propose in this work a novel MOEMS interferometer allowing operation over wider spectral range covering both the infrared (IR) and the visible ranges. The proposed architecture is based on spatial splitting and combining of optical beams using the imaging properties of Multi-Mode Interference MMI waveguide. The proposed structure includes an optical splitter for spatial splitting an input beam into two beams and a combiner for spatial combining the two interferometer beams. A MEMS moveable mirror is provided to produce an optical path difference between the two beams. The new interferometer is fabricated using DRIE technology on an SOI wafer. The movable mirror is metalized and attached to a comb-drive actuator fabricated in the same lithography step in a self-aligned manner on chip. The novel interferometer is tested as a Fourier transform spectrometer. Red laser, IR laser and absorption spectra of different materials are measured with a resolution of 2.5 nm at 635-nm wavelength. The structure is a very compact one that allows its integration and fabrication on a large scale with very low cost.

  15. Variation of the 3-μm absorption feature on Mars: observations over eastern Valles Marineris by the mariner 6 infrared spectrometer

    USGS Publications Warehouse

    Calvin, Wendy M.

    1997-01-01

    A new approach for calibration of the shortest wavelength channel (1.8 to 6.0 μm) of the Mariner 6 infrared spectrometer was derived. This calibration provides a new description of the instrument response function from 1.8 to 3.7 μm and accounts for the thermal contribution to the signal at longer wavelengths. This allows the two segments from 1.8 to 6 μm to be merged into a single spectrum. The broad water of hydration absorption spans these two segments and is examined in these merged spectra using a method of band integration. Unlike previous analyses which rely on ratios at two wavelengths, the integration method can assess the band strength independently from the albedo in the near infrared. Spectra taken over the eastern end of the Valles Marineris are examined for variations of the band-integrated value, and three distinct clusters are found. Within the estimated uncertainty, two clusters (both low and high albedo) have approximately the same integrated band depth. The third cluster (medium albedo) has an integrated band depth about 10% higher. This difference cannot be systematically attributed to either surface or atmospheric parameters and suggests variation in the amount of water either chemically or physically bound in surface materials. Approximately one-half of the high integrated band depth cluster is associated with chaotic terrain at the source of outflow channels, the other half occurs over lower inertia plains adjacent to chasmata. This suggests both surface physical properties and mineralogy as well as water in exchange with the atmosphere contribute to the 3-μm bound water absorption.

  16. Validation and calibration of a TDLAS oxygen sensor for in-line measurement on flow-packed products

    NASA Astrophysics Data System (ADS)

    Cocola, L.; Fedel, M.; Allermann, H.; Landa, S.; Tondello, G.; Bardenstein, A.; Poletto, L.

    2016-05-01

    A device based on Tunable Diode Laser Absorption Spectroscopy has been developed for non-invasive evaluation of gaseous oxygen concentration inside packed food containers. This work has been done in the context of the SAFETYPACK European project in order to enable full, automated product testing on a production line. The chosen samples at the end of the manufacturing process are modified atmosphere bags of processed mozzarella, in which the target oxygen concentration is required to be below 5%. The spectrometer allows in-line measurement of moving samples which are passing on a conveyor belt, with an optical layout optimized for bags made of a flexible scattering material, and works by sensing the gas phase in the headspace at the top of the package. A field applicable method for the calibration of this device has been identified and validated against traditional, industry standard, invasive measurement techniques. This allows some degrees of freedom for the end-user regarding packaging dimensions and shape. After deployment and setup of the instrument at the end-user manufacturing site, performance has been evaluated on a different range of samples in order to validate the choice of electro optical and geometrical parameters regarding sample handling and measurement timing at the actual measurement conditions.

  17. Near infrared cavity enhanced absorption spectra of atmospherically relevant ether-1, 4-Dioxane.

    PubMed

    Chandran, Satheesh; Varma, Ravi

    2016-01-15

    1, 4-Dioxane (DX) is a commonly found ether in industrially polluted atmosphere. The near infrared absorption spectra of this compound has been recorded in the region 5900-8230 cm(-1) with a resolution of 0.08 cm(-1) using a novel Fourier transform incoherent broadband cavity-enhanced absorption spectrometer (FT-IBBCEAS). All recorded spectra were found to contain regions that are only weakly perturbed. The possible combinations of fundamental modes and their overtone bands corresponding to selected regions in the measured spectra are tabulated. Two interesting spectral regions were identified as 5900-6400 cm(-1) and 8100-8230 cm(-1). No significant spectral interference due to presence of water vapor was observed suggesting the suitability of these spectral signatures for spectroscopic in situ detection of DX. The technique employed here is much more sensitive than standard Fourier transform spectrometer measurements on account of long effective path length achieved. Hence significant enhancement of weaker absorption lines above the noise level was observed as demonstrated by comparison with an available measurement from database. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Effective line intensity measurements of trans-nitrous acid (HONO) of the ν1 band near 3600 cm-1 using laser difference-frequency spectrometer

    NASA Astrophysics Data System (ADS)

    Maamary, Rabih; Fertein, Eric; Fourmentin, Marc; Dewaele, Dorothée; Cazier, Fabrice; Chen, Changshui; Chen, Weidong

    2017-07-01

    We report on the measurements of the effective line intensities of the ν1 fundamental band of trans-nitrous acid (trans-HONO) in the infrared near 3600 cm-1 (2.78 μm). A home-made widely tunable laser spectrometer based on difference-frequency generation (DFG) was used for this study. The strengths of 28 well-resolved absorption lines of the ν1 band were determined by scaling their absorption intensities to the well referenced absorption line intensity of the ν3 band of trans-HONO around 1250 cm-1 recorded simultaneously with the help of a DFB quantum cascade laser (QCL) spectrometer. The maximum measurement uncertainty of 12% in the line intensities is mainly determined by the uncertainty announced in the referenced line intensities, while the measurement precision in frequency positions of the absorption lines is better than 6×10-4 cm-1. The cross-measurement carried out in the present work allows one to perform intensity calibration using well referenced line parameters.

  19. Measuring the expressed abundance of the three phases of water with an imaging spectrometer over melting snow

    NASA Astrophysics Data System (ADS)

    Green, Robert O.; Painter, Thomas H.; Roberts, Dar A.; Dozier, Jeff

    2006-10-01

    From imaging spectrometer data, we simultaneously estimate the abundance of the three phases of water in an environment that includes melting snow, basing the analysis on the spectral shift in the absorption coefficient between water vapor, liquid water, and ice at 940, 980, and 1030 nm respectively. We apply a spectral fitting algorithm that measures the expressed abundance of the three phases of water to a data set acquired by the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) over Mount Rainier, Washington, on 14 June 1996. Precipitable water vapor varies from 1 mm over the summit of Mount Rainier to 10 mm over the lower valleys to the northwest. Equivalent path absorption of liquid water varies from 0 to 13 mm, with the zero values over rocky areas and high-elevation snow and the high values associated with liquid water held in vegetation canopies and in melting snow. Ice abundance varies from 0 to 30 mm equivalent path absorption in the snow- and glacier-covered portions of Mount Rainier. The water and ice abundances are related to the amount of liquid water and the sizes of the ice grains in the near-surface layer. Precision of the estimates, calculated over locally homogeneous areas, indicates an uncertainty of better than 1.5% for all three phases, except for liquid water in vegetation, where an optimally homogeneous site was not found. The analysis supports new strategies for hydrological research and applications as imaging spectrometers become more available.

  20. An integrated process analytical technology (PAT) approach to monitoring the effect of supercooling on lyophilization product and process parameters of model monoclonal antibody formulations.

    PubMed

    Awotwe Otoo, David; Agarabi, Cyrus; Khan, Mansoor A

    2014-07-01

    The aim of the present study was to apply an integrated process analytical technology (PAT) approach to control and monitor the effect of the degree of supercooling on critical process and product parameters of a lyophilization cycle. Two concentrations of a mAb formulation were used as models for lyophilization. ControLyo™ technology was applied to control the onset of ice nucleation, whereas tunable diode laser absorption spectroscopy (TDLAS) was utilized as a noninvasive tool for the inline monitoring of the water vapor concentration and vapor flow velocity in the spool during primary drying. The instantaneous measurements were then used to determine the effect of the degree of supercooling on critical process and product parameters. Controlled nucleation resulted in uniform nucleation at lower degrees of supercooling for both formulations, higher sublimation rates, lower mass transfer resistance, lower product temperatures at the sublimation interface, and shorter primary drying times compared with the conventional shelf-ramped freezing. Controlled nucleation also resulted in lyophilized cakes with more elegant and porous structure with no visible collapse or shrinkage, lower specific surface area, and shorter reconstitution times compared with the uncontrolled nucleation. Uncontrolled nucleation however resulted in lyophilized cakes with relatively lower residual moisture contents compared with controlled nucleation. TDLAS proved to be an efficient tool to determine the endpoint of primary drying. There was good agreement between data obtained from TDLAS-based measurements and SMART™ technology. ControLyo™ technology and TDLAS showed great potential as PAT tools to achieve enhanced process monitoring and control during lyophilization cycles. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

  1. Ultraviolet absorption experiment MA-059

    NASA Technical Reports Server (NTRS)

    Donahue, T. M.; Hudson, R. D.; Anderson, J.; Kaufman, F.; Mcelroy, M. B.

    1976-01-01

    The ultraviolet absorption experiment performed during the Apollo Soyuz mission involved sending a beam of atomic oxygen and atomic nitrogen resonance radiation, strong unabsorbable oxygen and nitrogen radiation, and visual radiation, all filling the same 3 deg-wide field of view from the Apollo to the Soyuz. The radiation struck a retroreflector array on the Soyuz and was returned to a spectrometer onboard the Apollo. The density of atomic oxygen and atomic nitrogen between the two spacecraft was measured by observing the amount of resonance radiation absorbed when the line joining Apollo and Soyuz was perpendicular to their velocity with respect to the ambient atmosphere. Information concerning oxygen densities was also obtained by observation of resonantly fluorescent light. The absorption experiments for atomic oxygen and atomic nitrogen were successfully performed at a range of 500 meters, and abundant resonance fluorescence data were obtained.

  2. Temperature dependence of the HNO3 UV absorption cross sections

    NASA Technical Reports Server (NTRS)

    Burkholder, James B.; Talukdar, Ranajit K.; Ravishankara, A. R.; Solomon, Susan

    1993-01-01

    The temperature dependence of the HNO3 absorption cross sections between 240 and 360 K over the wavelength range 195 to 350 nm has been measured using a diode array spectrometer. Absorption cross sections were determined using both (1) absolute pressure measurements at 298 K and (2) a dual absorption cell arrangement in which the absorption spectrum at various temperatures is measured relative to the room temperature absorption spectrum. The HNO3 absorption spectrum showed a temperature dependence which is weak at short wavelengths but stronger at longer wavelengths which are important for photolysis in the lower stratosphere. The 298 K absorption cross sections were found to be larger than the values currently recommended for atmospheric modeling (DeMore et al., 1992). Our absorption cross section data are critically compared with the previous measurements of both room temperature and temperature-dependent absorption cross sections. Temperature-dependent absorption cross sections of HNO3 are recommended for use in atmospheric modeling. These temperature dependent HNO3 absorption cross sections were used in a two-dimensional dynamical-photochemical model to demonstrate the effects of the revised absorption cross sections on loss rate of HNO3 and the abundance of NO2 in the stratosphere.

  3. Ultrafast nonlinear spectrometer for material characterization

    NASA Astrophysics Data System (ADS)

    Negres, Raluca Aurelia

    2001-11-01

    This work describes the use of a broadband spectral source for nonlinear spectroscopy to characterize various materials with potential applications in confocal microscopy, biological sample markers, optical limiting devices and optical switches. The goal is to study the spectrum of nonlinear absorption and the dispersion of nonlinear refraction as well as the dynamics of the nonlinearities by means of femtosecond excite-probe experiments. The principle is quite simple: if a sample is under the influence of a strong fs excitation pulse and a probe pulse beam is incident at the same time, or shortly after (within the decay time of the nonlinearity), then the probe pulse will sense the nonlinearity induced by the excitation. If the probe pulse is broadband, a femtosecond white-light continuum (WLC) in our case, we can monitor the nonlinearity induced over the entire continuum spectrum in one laser ``shot''. The use of femtosecond laser pulses to generate WLC will provide femtosecond time resolution for time-resolved spectroscopy. We built the nonlinear spectrometer and allowed for many degrees of flexibility in terms of choice of wavelengths for pump and probe beams and a dual detection system to cover both visible and infrared spectral ranges. We have the possibility of performing broad band spectral measurements using a spectrometer or selected narrow bandwidth probes incident on Si or Ge photodiodes, for improved S/N ratios. The intrinsic properties of the continuum probe demand a careful characterization of its spatial and temporal profile. Knowledge of the dispersion of the index of refraction in various optical elements, including the sample itself, is also required for a correct analysis of the transient absorption raw data, especially for short time-scale dynamics of nonlinear processes. We tested the system using well-characterized semiconductor samples, and the results came out in excellent agreement with those from previous picosecond Z-scan measurements

  4. Correlation spectrometer

    DOEpatents

    Sinclair, Michael B [Albuquerque, NM; Pfeifer, Kent B [Los Lunas, NM; Flemming, Jeb H [Albuquerque, NM; Jones, Gary D [Tijeras, NM; Tigges, Chris P [Albuquerque, NM

    2010-04-13

    A correlation spectrometer can detect a large number of gaseous compounds, or chemical species, with a species-specific mask wheel. In this mode, the spectrometer is optimized for the direct measurement of individual target compounds. Additionally, the spectrometer can measure the transmission spectrum from a given sample of gas. In this mode, infrared light is passed through a gas sample and the infrared transmission signature of the gasses present is recorded and measured using Hadamard encoding techniques. The spectrometer can detect the transmission or emission spectra in any system where multiple species are present in a generally known volume.

  5. High Sensitivity Absorption Spectroscopy on Ti II VUV Resonance Lines of Astrophysical Interest

    NASA Astrophysics Data System (ADS)

    Wiese, Lm; Fedchak, Ja; Lawler, Je

    2000-06-01

    The neutral hydrogen regions of the Interstellar Medium (ISM) of our Galaxy and distant galaxies produce simple absorption spectra because most metals are singly ionized and in their ground fine structure level. Elemental abundance measurements and other studies of the ISM rely on accurate atomic oscillator strengths (f-values) for a few key lines in the second spectra of Ti and other metals. The Ti II VUV resonance lines at 1910.6 and 1910.9 Åare important in absorption line systems in which quasars provide the continuum and the ISM of intervening galaxies is observed. Some of these absorption line systems are redshifted to the visible and observed with ground based telescopes. We report the first laboratory measurement of these Ti II VUV resonance lines. Using High Sensitivity Absorption Spectroscopy, we determined f-values for the 1910 Ålines relative to well-known Ti II resonance lines at 3067 and 3384 ÅContinuum radiation from an Aladdin Storage Ring bending magnet at the Synchrotron Radiation Center (SRC) is passed through a discharge plasma containing Ti^+. The transmitted light is analyzed by our 3m vacuum echelle spectrometer equipped with VUV sensitive CCD array. The resolving power of our spectrometer/detector array is 300,000. F-values are determined to within 10%.

  6. Oxygen, Neon, and Iron X-Ray Absorption in the Local Interstellar Medium

    NASA Technical Reports Server (NTRS)

    Gatuzz, Efrain; Garcia, Javier; Kallman, Timothy R.; Mendoza, Claudio

    2016-01-01

    We present a detailed study of X-ray absorption in the local interstellar medium by analyzing the X-ray spectra of 24 galactic sources obtained with the Chandra High Energy Transmission Grating Spectrometer and the XMM-Newton Reflection Grating Spectrometer. Methods. By modeling the continuum with a simple broken power-law and by implementing the new ISMabs X-ray absorption model, we have estimated the total H, O, Ne, and Fe column densities towards the observed sources. Results. We have determined the absorbing material distribution as a function of source distance and galactic latitude longitude. Conclusions. Direct estimates of the fractions of neutrally, singly, and doubly ionized species of O, Ne, and Fe reveal the dominance of the cold component, thus indicating an overall low degree of ionization. Our results are expected to be sensitive to the model used to describe the continuum in all sources.

  7. Tunable diode laser measurements of HO2NO2 absorption coefficients near 12.5 microns

    NASA Technical Reports Server (NTRS)

    May, R. D.; Molina, L. T.; Webster, C. R.

    1988-01-01

    A tunable diode laser spectrometer has been used to measure absorption coefficients of peroxynitric acid (HO2NO2) near the 803/cm Q branch. HO2NO2 concentrations in a low-pressure flowing gas mixture were determined from chemical titration procedures and UV absorption spectroscopy. The diode laser measured absorption coefficients, at a spectral resolution of better than 0.001/cm, are about 10 percent larger than previous Fourier transform infrared measurements made at a spectral resolution of 0.06/cm.

  8. Interfacing an aspiration ion mobility spectrometer to a triple quadrupole mass spectrometer

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

    Adamov, Alexey; Viidanoja, Jyrki; Kaerpaenoja, Esko

    2007-04-15

    This article presents the combination of an aspiration-type ion mobility spectrometer with a mass spectrometer. The interface between the aspiration ion mobility spectrometer and the mass spectrometer was designed to allow for quick mounting of the aspiration ion mobility spectrometer onto a Sciex API-300 triple quadrupole mass spectrometer. The developed instrumentation is used for gathering fundamental information on aspiration ion mobility spectrometry. Performance of the instrument is demonstrated using 2,6-di-tert-butyl pyridine and dimethyl methylphosphonate.

  9. Detection and quantification of snow algae with an airborne imaging spectrometer.

    PubMed

    Painter, T H; Duval, B; Thomas, W H; Mendez, M; Heintzelman, S; Dozier, J

    2001-11-01

    We describe spectral reflectance measurements of snow containing the snow alga Chlamydomonas nivalis and a model to retrieve snow algal concentrations from airborne imaging spectrometer data. Because cells of C. nivalis absorb at specific wavelengths in regions indicative of carotenoids (astaxanthin esters, lutein, beta-carotene) and chlorophylls a and b, the spectral signature of snow containing C. nivalis is distinct from that of snow without algae. The spectral reflectance of snow containing C. nivalis is separable from that of snow without algae due to carotenoid absorption in the wavelength range from 0.4 to 0.58 microm and chlorophyll a and b absorption in the wavelength range from 0.6 to 0.7 microm. The integral of the scaled chlorophyll a and b absorption feature (I(0.68)) varies with algal concentration (C(a)). Using the relationship C(a) = 81019.2 I(0.68) + 845.2, we inverted Airborne Visible Infrared Imaging Spectrometer reflectance data collected in the Tioga Pass region of the Sierra Nevada in California to determine algal concentration. For the 5.5-km(2) region imaged, the mean algal concentration was 1,306 cells ml(-1), the standard deviation was 1,740 cells ml(-1), and the coefficient of variation was 1.33. The retrieved spatial distribution was consistent with observations made in the field. From the spatial estimates of algal concentration, we calculated a total imaged algal biomass of 16.55 kg for the 0.495-km(2) snow-covered area, which gave an areal biomass concentration of 0.033 g/m(2).

  10. Detection and Quantification of Snow Algae with an Airborne Imaging Spectrometer

    PubMed Central

    Painter, Thomas H.; Duval, Brian; Thomas, William H.; Mendez, Maria; Heintzelman, Sara; Dozier, Jeff

    2001-01-01

    We describe spectral reflectance measurements of snow containing the snow alga Chlamydomonas nivalis and a model to retrieve snow algal concentrations from airborne imaging spectrometer data. Because cells of C. nivalis absorb at specific wavelengths in regions indicative of carotenoids (astaxanthin esters, lutein, β-carotene) and chlorophylls a and b, the spectral signature of snow containing C. nivalis is distinct from that of snow without algae. The spectral reflectance of snow containing C. nivalis is separable from that of snow without algae due to carotenoid absorption in the wavelength range from 0.4 to 0.58 μm and chlorophyll a and b absorption in the wavelength range from 0.6 to 0.7 μm. The integral of the scaled chlorophyll a and b absorption feature (I0.68) varies with algal concentration (Ca). Using the relationship Ca = 81019.2 I0.68 + 845.2, we inverted Airborne Visible Infrared Imaging Spectrometer reflectance data collected in the Tioga Pass region of the Sierra Nevada in California to determine algal concentration. For the 5.5-km2 region imaged, the mean algal concentration was 1,306 cells ml−1, the standard deviation was 1,740 cells ml−1, and the coefficient of variation was 1.33. The retrieved spatial distribution was consistent with observations made in the field. From the spatial estimates of algal concentration, we calculated a total imaged algal biomass of 16.55 kg for the 0.495-km2 snow-covered area, which gave an areal biomass concentration of 0.033 g/m2. PMID:11679355

  11. 21 Tesla Fourier Transform Ion Cyclotron Resonance Mass Spectrometer Greatly Expands Mass Spectrometry Toolbox

    NASA Astrophysics Data System (ADS)

    Shaw, Jared B.; Lin, Tzu-Yung; Leach, Franklin E.; Tolmachev, Aleksey V.; Tolić, Nikola; Robinson, Errol W.; Koppenaal, David W.; Paša-Tolić, Ljiljana

    2016-12-01

    We provide the initial performance evaluation of a 21 Tesla Fourier transform ion cyclotron resonance mass spectrometer operating at the Environmental Molecular Sciences Laboratory at the Pacific Northwest National Laboratory. The spectrometer constructed for the 21T system employs a commercial dual linear ion trap mass spectrometer coupled to a FTICR spectrometer designed and built in-house. Performance gains from moving to higher magnetic field strength are exemplified by the measurement of peptide isotopic fine structure, complex natural organic matter mixtures, and large proteins. Accurate determination of isotopic fine structure was demonstrated for doubly charged Substance P with minimal spectral averaging, and 8158 molecular formulas assigned to Suwannee River Fulvic Acid standard with root-mean-square (RMS) error of 10 ppb. We also demonstrated superior performance for intact proteins; namely, broadband isotopic resolution of the entire charge state distribution of apo-transferrin (78 kDa) and facile isotopic resolution of monoclonal antibody under a variety of acquisition parameters (e.g., 6 s time-domains with absorption mode processing yielded resolution of approximately 1 M at m/z = 2700).

  12. 21 Tesla Fourier Transform Ion Cyclotron Resonance Mass Spectrometer Greatly Expands Mass Spectrometry Toolbox

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

    Shaw, Jared B.; Lin, Tzu-Yung; Leach, Franklin E.

    We provide the initial performance evaluation of a 21 Tesla Fourier transform ion cyclotron resonance mass spectrometer operating at the Environmental Molecular Sciences Laboratory at Pacific Northwest National Laboratory. The spectrometer constructed for the 21T system employs a commercial dual linear ion trap mass spectrometer coupled to a FTICR spectrometer designed and built in-house. Performance gains from moving to higher magnetic field strength are exemplified by the measurement of peptide isotopic fine structure, complex natural organic matter mixtures, and large proteins. Accurate determination of isotopic fine structure was demonstrated for doubly charged substance P with minimal spectral averaging, and 8,158more » molecular formulas assigned to Suwannee River Fulvic Acid standard with RMS error of 10 ppb. We also demonstrated superior performance for intact proteins; namely, broadband isotopic resolution of the entire charge state distribution of apotransferrin (78 kDa) and facile isotopic resolution of monoclonal antibody under a variety of acquisition parameters (e.g. 6 s time-domains with absorption mode processing yielded resolution of approximately 1M at m/z =2,700).« less

  13. Quantification of CO2 and CH4 megacity emissions using portable solar absorption spectrometers

    NASA Astrophysics Data System (ADS)

    Frey, Matthias; Hase, Frank; Blumenstock, Thomas; Morino, Isamu; Shiomi, Kei

    2017-04-01

    Urban areas already contribute to over 50% of the global population, additionally the percentage of the worldwide population living in Metropolitan areas is continuously growing. Thus, a precise knowledge of urban greenhouse gas (GHG) emissions is of utmost importance. Whereas, however, GHG emissions on a nationwide to continental scale can be relatively precisely estimated using satellite observations (and fossil fuel consumption statistics), reliable estimations for local to regional scale emissions pose a bigger problem due to lack of timely and spatially high resolved satellite data and possible biases of passive spectroscopic nadir observations (e.g. enhanced aerosol scattering in a city plume). Furthermore, emission inventories on the city scale might be missing contributions (e.g. methane leakage from gas pipes). Here, newly developed mobile low resolution Fourier Transform spectrometers (Bruker EM27/SUN) are utilized to quantify small scale emissions. This novel technique was successfully tested before by KIT and partners during campaigns in Berlin, Paris and Colorado for detecting emissions from various sources. We present results from a campaign carried out in February - April 2016 in the Tokyo bay area, one of the biggest Metropolitan areas worldwide. We positioned two EM27/SUN spectrometers on the outer perimeter of Tokyo along the prevailing wind axis upwind and downwind of the city source. Before and after the campaign, calibration measurements were performed in Tsukuba with a collocated high resolution FTIR spectrometer from the Total Carbon Column Observing Network (TCCON). During the campaign the observed XCO2 and XCH4 values vary significantly. Additionally, intraday variations are observed at both sites. Furthermore, an enhancement due to the Tokyo area GHG emissions is clearly visible for both XCO2 and XCH4. The observed signals are significantly higher compared to prior campaigns targeting other major cities. We perform a rough estimate of the

  14. Near shot-noise limited time-resolved circular dichroism pump-probe spectrometer

    NASA Astrophysics Data System (ADS)

    Stadnytskyi, Valentyn; Orf, Gregory S.; Blankenship, Robert E.; Savikhin, Sergei

    2018-03-01

    We describe an optical near shot-noise limited time-resolved circular dichroism (TRCD) pump-probe spectrometer capable of reliably measuring circular dichroism signals in the order of μdeg with nanosecond time resolution. Such sensitivity is achieved through a modification of existing TRCD designs and introduction of a new data processing protocol that eliminates approximations that have caused substantial nonlinearities in past measurements and allows the measurement of absorption and circular dichroism transients simultaneously with a single pump pulse. The exceptional signal-to-noise ratio of the described setup makes the TRCD technique applicable to a large range of non-biological and biological systems. The spectrometer was used to record, for the first time, weak TRCD kinetics associated with the triplet state energy transfer in the photosynthetic Fenna-Matthews-Olson antenna pigment-protein complex.

  15. On the accuracy of aerosol photoacoustic spectrometer calibrations using absorption by ozone

    NASA Astrophysics Data System (ADS)

    Davies, Nicholas W.; Cotterell, Michael I.; Fox, Cathryn; Szpek, Kate; Haywood, Jim M.; Langridge, Justin M.

    2018-04-01

    In recent years, photoacoustic spectroscopy has emerged as an invaluable tool for the accurate measurement of light absorption by atmospheric aerosol. Photoacoustic instruments require calibration, which can be achieved by measuring the photoacoustic signal generated by known quantities of gaseous ozone. Recent work has questioned the validity of this approach at short visible wavelengths (404 nm), indicating systematic calibration errors of the order of a factor of 2. We revisit this result and test the validity of the ozone calibration method using a suite of multipass photoacoustic cells operating at wavelengths 405, 514 and 658 nm. Using aerosolised nigrosin with mobility-selected diameters in the range 250-425 nm, we demonstrate excellent agreement between measured and modelled ensemble absorption cross sections at all wavelengths, thus demonstrating the validity of the ozone-based calibration method for aerosol photoacoustic spectroscopy at visible wavelengths.

  16. A nearly on-axis spectroscopic system for simultaneously measuring UV-visible absorption and X-ray diffraction in the SPring-8 structural genomics beamline.

    PubMed

    Sakaguchi, Miyuki; Kimura, Tetsunari; Nishida, Takuma; Tosha, Takehiko; Sugimoto, Hiroshi; Yamaguchi, Yoshihiro; Yanagisawa, Sachiko; Ueno, Go; Murakami, Hironori; Ago, Hideo; Yamamoto, Masaki; Ogura, Takashi; Shiro, Yoshitsugu; Kubo, Minoru

    2016-01-01

    UV-visible absorption spectroscopy is useful for probing the electronic and structural changes of protein active sites, and thus the on-line combination of X-ray diffraction and spectroscopic analysis is increasingly being applied. Herein, a novel absorption spectrometer was developed at SPring-8 BL26B2 with a nearly on-axis geometry between the X-ray and optical axes. A small prism mirror was placed near the X-ray beamstop to pass the light only 2° off the X-ray beam, enabling spectroscopic analysis of the X-ray-exposed volume of a crystal during X-ray diffraction data collection. The spectrometer was applied to NO reductase, a heme enzyme that catalyzes NO reduction to N2O. Radiation damage to the heme was monitored in real time during X-ray irradiation by evaluating the absorption spectral changes. Moreover, NO binding to the heme was probed via caged NO photolysis with UV light, demonstrating the extended capability of the spectrometer for intermediate analysis.

  17. Evaluation of hydrogen absorption cells for observations of the planetary coronas

    NASA Astrophysics Data System (ADS)

    Kuwabara, M.; Taguchi, M.; Yoshioka, K.; Ishida, T.; de Oliveira, N.; Ito, K.; Kameda, S.; Suzuki, F.; Yoshikawa, I.

    2018-02-01

    Newly designed Lyman-alpha absorption cells for imaging hydrogen planetary corona were characterized using an ultra high resolution Fourier transform spectrometer installed on the DESIRS (Dichroïsme Et Spectroscopie par Interaction avec le Rayonnement Synchrotron) beamline of Synchrotron SOLEIL in France. The early absorption cell installed in the Japanese Mars orbiter NOZOMI launched in 1998 had not been sufficiently optimized due to its short development time. The new absorption cells are equipped with the ability to change various parameters, such as filament shape, applied power, H2 gas pressure, and geometrical configuration. We found that the optical thickness of the new absorption cell was ˜4 times higher than the earlier one at the center wavelength of Lyman-alpha absorption, by optimizing the condition to promote thermal dissociation of H2 molecules into two H atoms on a hot tungsten filament. The Doppler temperature of planetary coronas could be determined with an accuracy better than 100 K with the performance of the newly developed absorption cell.

  18. Hydrogen and Nitrogen Broadened Ethane and Propane Absorption Cross Sections

    NASA Astrophysics Data System (ADS)

    Hargreaves, Robert J.; Appadoo, Dominique; Billinghurst, Brant E.; Bernath, Peter F.

    2015-06-01

    High-resolution infrared absorption cross sections are presented for the ν9 band of ethane (C2H6) at 823 cm-1. These cross sections make use of spectra recorded at the Australian Synchrotron using a Fourier transform infrared spectrometer with maximum resolution of 0.00096 cm-1. The spectra have been recorded at 150, 120 and 90 K for hydrogen and nitrogen broadened C2H6. They cover appropriate temperatures, pressures and broadening gases associated with the atmospheres of the Outer Planets and Titan, and will improve atmospheric retrievals. The THz/Far-IR beamline at the Australian Synchrotron is unique in combining a high-resolution Fourier transform spectrometer with an 'enclosive flow cooling' (EFC) cell designed to study molecules at low temperatures. The EFC cell is advantageous at temperatures for which the vapor pressure is very low, such as C2H6 at 90 K. Hydrogen broadened absorption cross sections of propane between 700 and 1200 cm-1 will also be presented based on spectra obtained at the Canadian Light Source.

  19. VCSEL-based oxygen spectroscopy for structural analysis of pharmaceutical solids

    NASA Astrophysics Data System (ADS)

    Svensson, T.; Andersson, M.; Rippe, L.; Svanberg, S.; Andersson-Engels, S.; Johansson, J.; Folestad, S.

    2008-02-01

    We present a minimalistic and flexible single-beam instrumentation based on sensitive tunable diode laser absorption spectroscopy (TDLAS) and its use in structural analysis of highly scattering pharmaceutical solids. By utilising a vertical cavity surface emitting laser (VCSEL) for sensing of molecular oxygen dispersed in tablets, we address structural properties such as porosity. Experiments involve working with unknown path lengths, severe backscattering and diffuse light. These unusual experimental conditions has led to the use of the term gas in scattering media absorption spectroscopy (GASMAS). By employing fully digital wavelength modulation spectroscopy and coherent sampling, system sensitivity in ambient air experiments reaches the 10-7 range. Oxygen absorption exhibited by our tablets, being influenced by both sample porosity and scattering, was in the range 8×10-5 to 2×10-3, and corresponds to 2-50 mm of path length through ambient air (Leq). The day-to-day reproducibility was on average 1.8% (0.3 mm Leq), being limited by mechanical positioning. This is the first time sub-millimetre sensitivity is reached in GASMAS. We also demonstrate measurements on gas transport on a 1-s time scale. By employing pulsed illumination and time-correlated single-photon counting, we reveal that GASMAS exhibits excellent correlation with time-domain photon migration. In addition, we introduce an optical measure of porosity by relating oxygen absorption to average photon time-of-flight. Finally, the simplicity, robustness and low cost of this novel TDLAS instrumentation provide industrial potential.

  20. Using high spectral resolution spectrophotometry to study broad mineral absorption features on Mars

    NASA Technical Reports Server (NTRS)

    Blaney, D. L.; Crisp, D.

    1993-01-01

    Traditionally telescopic measurements of mineralogic absorption features have been made using relatively low to moderate (R=30-300) spectral resolution. Mineralogic absorption features tend to be broad so high resolution spectroscopy (R greater than 10,000) does not provide significant additional compositional information. Low to moderate resolution spectroscopy allows an observer to obtain data over a wide wavelength range (hundreds to thousands of wavenumbers) compared to the several wavenumber intervals that are collected using high resolution spectrometers. However, spectrophotometry at high resolution has major advantages over lower resolution spectroscopy in situations that are applicable to studies of the Martian surface, i.e., at wavelengths where relatively weak surface absorption features and atmospheric gas absorption features both occur.

  1. Versatile mid-infrared frequency-comb referenced sub-Doppler spectrometer

    NASA Astrophysics Data System (ADS)

    Gambetta, A.; Vicentini, E.; Coluccelli, N.; Wang, Y.; Fernandez, T. T.; Maddaloni, P.; De Natale, P.; Castrillo, A.; Gianfrani, L.; Laporta, P.; Galzerano, G.

    2018-04-01

    We present a mid-IR high-precision spectrometer capable of performing accurate Doppler-free measurements with absolute calibration of the optical axis and high signal-to-noise ratio. The system is based on a widely tunable mid-IR offset-free frequency comb and a Quantum-Cascade-Laser (QCL). The QCL emission frequency is offset locked to one of the comb teeth to provide absolute-frequency calibration, spectral-narrowing, and accurate fine frequency tuning. Both the comb repetition frequency and QCL-comb offset frequency can be modulated to provide, respectively, slow- and fast-frequency-calibrated scanning capabilities. The characterisation of the spectrometer is demonstrated by recording sub-Doppler saturated absorption features of the CHF3 molecule at around 8.6 μm with a maximum signal-to-noise ratio of ˜7 × 103 in 10 s integration time, frequency-resolution of 160 kHz, and accuracy of less than 10 kHz.

  2. Temperature dependence of the ClONO{sub 2} UV absorption spectrum

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

    Burkholder, J.B.; Talukdar, R.K.; Ravishankara, A.R.

    1994-04-01

    The temperature dependence of the ClONO{sub 2} absorption spectrum has been measured between 220 and 298 K and between 195 and 430 nm using a diode array spectrometer. The absorption cross sections were determined using both: (1) absolute pressure measurements at 296 K and (2) measurements at various temperatures relative to 296 K using a dual absorption cell arrangement. The temperature dependence of the ClONO{sub 2} absorption spectrum shows very broad structure. The amplitude of the temperature dependence relative to that at 296 K is weak at short wavelengths, < 2% at 215 nm and 220 K, but significant atmore » the wavelengths important in the stratosphere, {approximately} 30% at 325 nm and 220 K. The authors ClONO{sub 2} absorption cross section data are in good general agreement with the previous measurements of Molina and Molina.« less

  3. The superconducting high-resolution soft X-ray spectrometer at the advanced biological and environmental X-ray facility

    NASA Astrophysics Data System (ADS)

    Friedrich, S.; Drury, O. B.; George, S. J.; Cramer, S. P.

    2007-11-01

    We have built a 36-pixel superconducting tunnel junction X-ray spectrometer for chemical analysis of dilute samples in the soft X-ray band. It offers an energy resolution of ˜10-20 eV FWHM below 1 keV, a solid angle coverage of ˜10 -3, and can be operated at total rates of up to ˜10 6 counts/s. Here, we describe the spectrometer performance in speciation measurements by fluorescence-detected X-ray absorption spectroscopy at the Advanced Biological and Environmental X-ray facility at the ALS synchrotron.

  4. PIR-fiber spectroscopy with FTIR and TDL spectrometers in the middle infared range of spectra

    NASA Astrophysics Data System (ADS)

    Artjushenko, Vjacheslav G.; Afanasyeva, Natalia I.; Bruch, Reinhard F.; Daniellian, G.; Stepanov, Eugene V.

    2000-07-01

    Development of Polycrystalline Infrared (PIR-) fibers extruded from solid solutions of AgCl/AgBr has opened a new horizon of molecular spectroscopy applications in 4 - 18 micron range of spectra. PIR-fiber cables and probes could be coupled with a variety of Fourier Transform Infrared spectrometer and Tunable Diode Lasers (TDL), including pig tailing of Mercury Cadmium Tellurium (MCT) detectors. Using these techniques no sample preparation is necessary for PIR- fiber probes to measure reflection and absorption spectra, in situ, in vivo, in real time and even multiplexed. Such PIR-fiber probes have been used for evanescent absorption spectroscopy of malignant tissue and skin surface diagnostics in-vivo, glucose detection in blood as well as crude oil composition analysis, for organic pollution and nuclear waste monitoring. A review of various PIR-fiber applications in medicine, industry and environment control is presented. The synergy of PIR-fibers flexibility with a super high resolution of TDL spectrometers with (Delta) v equals 10-4 cm-1, provides the unique tool for gas analysis, specifically when PIR-fibers are coupled as pigtails with MCT-detectors, and Pb-salt lasers. Design of multichannel PIR-fiber tailed TDL spectrometer could be used as a portable device for multispectral gas analysis at 1 ppb level of detectivity for various applications in medicine and biotechnology.

  5. The development and evaluation of airborne in situ N2O and CH4 sampling using a Quantum Cascade Laser Absorption Spectrometer (QCLAS)

    NASA Astrophysics Data System (ADS)

    Pitt, Joseph; Le Breton, Michael; Allen, Grant; Percival, Carl; Gallagher, Martin; Bauguitte, Stephane; O'Shea, Sebastian; Muller, Jennifer; Zahniser, Mark; Pyle, John; Palmer, Paul

    2016-04-01

    Spectroscopic measurements of atmospheric N2O and CH4 mole fractions were made on board the FAAM (Facility for Airborne Atmospheric Measurements) large Atmospheric Research Aircraft. We evaluate the performance of the mid-IR continuous wave Aerodyne Research Inc. Quantum Cascade Laser Absorption Spectrometer (QCLAS) employed over 17 flights conducted during summer 2014. Two different methods of correcting for the influence of water vapour on the spectroscopic retrievals are compared and evaluated. Test flight data demonstrating the sensitivity of the instrument to changes in cabin pressure is presented, and a new in-flight calibration procedure to account for this issue is described and assessed. Total 1σ uncertainties of 1.81 ppb for CH4 and 0.35 ppb for N2O are derived. We report a mean difference in 1 Hz CH4 mole fraction of 2.05 ppb (1σ = 5.85 ppb) between in-flight measurements made using the QCLAS and simultaneous measurements using a previously characterised Los Gatos Research Fast Greenhouse Gas Analyser (FGGA).

  6. The development and evaluation of airborne in situ N2O and CH4 sampling using a Quantum Cascade Laser Absorption Spectrometer (QCLAS)

    NASA Astrophysics Data System (ADS)

    Pitt, J. R.; Le Breton, M. R.; Allen, G.; Percival, C.; Gallagher, M. W.; Bauguitte, S.; O'Shea, S.; Muller, J.; Zahniser, M. S.; Pyle, J. A.; Palmer, P. I.

    2015-12-01

    Spectroscopic measurements of atmospheric N2O and CH4 mole fractions were made on board the FAAM (Facility for Airborne Atmospheric Measurements) large Atmospheric Research Aircraft. We evaluate the performance of the mid-IR continuous wave Aerodyne Research Inc. Quantum Cascade Laser Absorption Spectrometer (QCLAS) employed over 17 flights conducted during summer 2014. Two different methods of correcting for the influence of water vapour on the spectroscopic retrievals are compared and evaluated. Test flight data demonstrating the sensitivity of the instrument to changes in cabin pressure is presented, and a new in-flight calibration procedure to account for this issue is described and assessed. Total 1σ uncertainties of 1.81 ppb for CH4 and 0.35 ppb for N2O are derived. We report a mean difference in 1 Hz CH4 mole fraction of 2.05 ppb (1σ = 5.85 ppb) between in-flight measurements made using the QCLAS and simultaneous measurements using a previously characterised Los Gatos Research Fast Greenhouse Gas Analyser (FGGA).

  7. Demonstration of a Strategy to Perform Two-Dimensional Diode Laser Tomography

    DTIC Science & Technology

    2008-03-01

    training set allows interpolation between beam paths resulting in temperature and density maps. Finally, the TDLAS temperature and density maps are... TDLAS and Tomography Results .................................................................. 38 Introduction...38 vii Page TDLAS Burner Setup

  8. Evaluating Field Spectrometer Performance with Transmission Standards: Examples from the USGS Spectral Library and Research Databases

    NASA Astrophysics Data System (ADS)

    Hoefen, T. M.; Kokaly, R. F.; Swayze, G. A.; Livo, K. E.

    2015-12-01

    Collection of spectroscopic data has expanded with the development of field-portable spectrometers. The most commonly available spectrometers span one or several wavelength ranges: the visible (VIS) and near-infrared (NIR) region from approximately 400 to 1000 nm, and the shortwave infrared (SWIR) region from approximately 1000-2500 nm. Basic characteristics of spectrometer performance are the wavelength position and bandpass of each channel. Bandpass can vary across the wavelength coverage of an instrument, due to spectrometer design and detector materials. Spectrometer specifications can differ from one instrument to the next for a given model and between manufacturers. The USGS Spectroscopy Lab in Denver has developed a simple method to evaluate field spectrometer wavelength accuracy and bandpass values using transmission measurements of materials with intense, narrow absorption features, including Mylar* plastic, praseodymium-doped glass, and National Institute of Standards and Technology Standard Reference Material 2035. The evaluation procedure has been applied in laboratory and field settings for 19 years and used to detect deviations from cited manufacturer specifications. Tracking of USGS spectrometers with transmission standards has revealed several instances of wavelength shifts due to wear in spectrometer components. Since shifts in channel wavelengths and differences in bandpass between instruments can impact the use of field spectrometer data to calibrate and analyze imaging spectrometer data, field protocols to measure wavelength standards can limit data loss due to spectrometer degradation. In this paper, the evaluation procedure will be described and examples of observed wavelength shifts during a spectrometer field season will be presented. The impact of changing wavelength and bandpass characteristics on spectral measurements will be demonstrated and implications for spectral libraries will be discussed. *Any use of trade, firm, or product names

  9. Monolithic spectrometer

    DOEpatents

    Rajic, Slobodan; Egert, Charles M.; Kahl, William K.; Snyder, Jr., William B.; Evans, III, Boyd M.; Marlar, Troy A.; Cunningham, Joseph P.

    1998-01-01

    A monolithic spectrometer is disclosed for use in spectroscopy. The spectrometer is a single body of translucent material with positioned surfaces for the transmission, reflection and spectral analysis of light rays.

  10. Tropospheric Emission Spectrometer and Airborne Emission Spectrometer

    NASA Technical Reports Server (NTRS)

    Glavich, T.; Beer, R.

    1996-01-01

    The Tropospheric Emission Spectrometer (TES) is an instrument being developed for the NASA Earth Observing System Chemistry Platform. TES will measure the distribution of ozone and its precursors in the lower atmosphere. The Airborne Emission Spectrometer (AES) is an aircraft precursor to TES. Applicable descriptions are given of instrument design, technology challenges, implementation and operations for both.

  11. Absorption coefficients of CFC-11 and CFC-12 needed for atmospheric remote sensing and global warming studies

    NASA Technical Reports Server (NTRS)

    Varanasi, Prasad

    1992-01-01

    Spectral absorption coefficients k(v) in the atmospheric window are reported for CFC-11 and CFC-12. Data obtained with a grating spectrometer are compared with NCAR cross sections and measurements of k(v) made with a tunable diode laser spectrometer at various temperature-pressure combinations representing tangent heights or layers in the atmosphere are presented. The results are suitable for atmospheric remote sensing and global warming studies.

  12. Monolithic spectrometer

    DOEpatents

    Rajic, S.; Egert, C.M.; Kahl, W.K.; Snyder, W.B. Jr.; Evans, B.M. III; Marlar, T.A.; Cunningham, J.P.

    1998-05-19

    A monolithic spectrometer is disclosed for use in spectroscopy. The spectrometer is a single body of translucent material with positioned surfaces for the transmission, reflection and spectral analysis of light rays. 6 figs.

  13. In situ metrology to characterize water vapor delivery during atomic layer deposition

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

    Ahmido, Tariq, E-mail: tariq.ahmido@nist.gov; Kimes, William A.; Sperling, Brent A.

    Water is often employed as the oxygen source in metal oxide atomic layer deposition (ALD) processes. It has been reported that variations in the amount of water delivered during metal oxide ALD can impact the oxide film properties. Hence, one contribution to optimizing metal oxide ALD processes would be to identify methods to better control water dose. The development of rapid, quantitative techniques for in situ water vapor measurements during ALD processes would be beneficial to achieve this goal. In this report, the performance of an in situ tunable diode laser absorption spectroscopy (TDLAS) scheme for performing rapid, quantitative watermore » partial pressure measurements in a representative quarter-inch ALD delivery line is described. This implementation of TDLAS, which utilizes a near-infrared distributed-feedback diode laser and wavelength modulation spectroscopy, provides measurements of water partial pressure on a timescale comparable to or shorter than the timescale of the gas dynamics in typical ALD systems. Depending on the degree of signal averaging, this TDLAS system was capable of measuring the water partial pressure with a detection limit in the range of ∼0.80 to ∼0.08 Pa. The utility of this TDLAS scheme was demonstrated by using it to identify characteristics of a representative water delivery system that otherwise would have been difficult to predict. Those characteristics include (1) the magnitude and time dependence of the pressure transient that can occur during water injection, and (2) the dependence of the steady-state water partial pressure on the carrier gas flow rate and the setting of the water ampoule flow restriction.« less

  14. The Joint Astrophysical Plasmadynamic Experiment (J-PEX): a high-resolution rocket spectrometer

    NASA Astrophysics Data System (ADS)

    Barstow, Martin A.; Bannister, Nigel P.; Cruddace, Raymond G.; Kowalski, Michael P.; Wood, Kent S.; Yentis, Daryl J.; Gursky, Herbert; Barbee, Troy W., Jr.; Goldstein, William H.; Kordas, Joseph F.; Fritz, Gilbert G.; Culhane, J. Leonard; Lapington, Jonathan S.

    2003-02-01

    We report on the successful sounding rocket flight of the high resolution (R=3000-4000) J-PEX EUV spectrometer. J-PEX is a novel normal incidence instrument, which combines the focusing and dispersive elements of the spectrometer into a single optical element, a multilayer-coated grating. The high spectral resolution achieved has had to be matched by unprecedented high spatial resolution in the imaging microchannel plate detector used to record the data. We illustrate the performance of the complete instrument through an analysis of the 220-245Å spectrum of the white dwarf G191-B2B obtained with a 300 second exposure. The high resolution allows us to detect a low-density ionized helium component along the line of sight to the star and individual absorption lines from heavier elements in the photosphere.

  15. 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

  16. Preliminary analysis of Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) for mineralogic mapping at sites in Nevada and Colorado

    NASA Technical Reports Server (NTRS)

    Kruse, Fred A.; Taranik, Dan L.; Kierein-Young, Kathryn S.

    1988-01-01

    Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data for sites in Nevada and Colorado were evaluated to determine their utility for mineralogical mapping in support of geologic investigations. Equal energy normalization is commonly used with imaging spectrometer data to reduce albedo effects. Spectra, profiles, and stacked, color-coded spectra were extracted from the AVIRIS data using an interactive analysis program (QLook) and these derivative data were compared to Airborne Imaging Spectrometer (AIS) results, field and laboratory spectra, and geologic maps. A feature extraction algorithm was used to extract and characterize absorption features from AVIRIS and laboratory spectra, allowing direct comparison of the position and shape of absorption features. Both muscovite and carbonate spectra were identified in the Nevada AVIRIS data by comparison with laboratory and AIS spectra, and an image was made that showed the distribution of these minerals for the entire site. Additional, distinctive spectra were located for an unknown mineral. For the two Colorado sites, the signal-to-noise problem was significantly worse and attempts to extract meaningful spectra were unsuccessful. Problems with the Colorado AVIRIS data were accentuated by the IAR reflectance technique because of moderate vegetation cover. Improved signal-to-noise and alternative calibration procedures will be required to produce satisfactory reflectance spectra from these data. Although the AVIRIS data were useful for mapping strong mineral absorption features and producing mineral maps at the Nevada site, it is clear that significant improvements to the instrument performance are required before AVIRIS will be an operational instrument.

  17. A Capillary Absorption Spectrometer for Stable Carbon Isotope Ratio (13C/12C) Analysis in Very Small Samples

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

    Kelly, James F.; Sams, Robert L.; Blake, Thomas A.

    2012-02-06

    A capillary absorption spectrometer (CAS) suitable for IR laser isotope analysis of small CO{sub 2} samples is presented. The system employs a continuous-wave (cw) quantum cascade laser to study nearly adjacent rovibrational transitions of different isotopologues of CO{sub 2} near 2307 cm{sup -1} (4.34 {mu}m). This initial CAS system can achieve relative isotopic precision of about 10 ppm {sup 13}C, or {approx}1{per_thousand} (per mil in delta notation relative to Vienna Pee Dee Belemnite) with 20-100 picomoles of entrained sample within the hollow waveguide for CO{sub 2} concentrations {approx}400 to 750 ppm. Isotopic analyses of such gas fills in a 1-mmmore » ID hollow waveguide of 0.8 m overall physical path length can be carried out down to {approx}2 Torr. Overall {sup 13}C/{sup 12}C ratios can be calibrated to {approx}2{per_thousand} accuracy with diluted CO{sub 2} standards. A novel, low-cost method to reduce cw-fringing noise resulting from multipath distortions in the hollow waveguide is presented, which allows weak absorbance features to be studied at the few ppm level (peak-to-rms) after 1,000 scans are co-added in {approx}10 sec. The CAS is meant to work directly with converted CO{sub 2} samples from a Laser Ablation-Catalytic-Combustion (LA CC) micro-sampler to provide {sup 13}C/{sup 12}C ratios of small biological isolates with spatial resolutions {approx}50 {mu}m.« less

  18. Development of a Qcl-Based Spectrometer for Spectroscopic Analysis of Biogenic Volatile Organic Compounds

    NASA Astrophysics Data System (ADS)

    Iranpour, Michael Cyrus; Tran, Minh Nhat; Stewart, Jacob

    2017-06-01

    Biogenic volatile organic compounds (BVOCs) are naturally occurring molecules that are emitted into the atmosphere by plants. BVOCs have an important role in atmospheric chemistry as they react readily with ozone, hydroxyl radicals, and nitric oxides to form aerosols and pollutants such as ozone in the troposphere. We are developing an IR spectrometer with the aim of measuring spectra of atmospheric samples of BVOCs to determine their concentrations. Using an external cavity quantum cascade laser (EC-QCL), we have acquired IR spectra of isoprene (C_{5}H_{8}) near 993 cm^{-1}. Isoprene represents an ideal target, as it is the simplest and most abundant BVOC. IR spectra of standard samples of isoprene were acquired in order to determine the detection limit of the spectrometer. We have also been working to improve the capabilities of the spectrometer by implementing wavelength modulation spectroscopy and increasing the path length through our samples by using a multipass cell. In this talk, we will present data from our initial measurements of the standard isoprene samples using a simple direct absorption setup as well as measurements using the improved spectrometer.

  19. Dynamic light absorption of biomass burning organic carbon photochemically aged under natural sunlight

    NASA Astrophysics Data System (ADS)

    Zhong, M.; Jang, M.

    2013-08-01

    Wood burning aerosol produced under smoldering conditions was photochemically aged with different relative humidity (RH) and NOx conditions using a 104 m3 dual outdoor chamber under natural sunlight. Light absorption of organic carbon (OC) was measured over the course of photooxidation using a UV-visible spectrometer connected to an integrating sphere. At high RH, the color decayed rapidly. NOx slightly prolonged the color of wood smoke, suggesting that NOx promotes the formation of chromophores via secondary processes. Overall, the mass absorption cross-section (integrated between 280 nm and 600 nm) of OC increased by 11-54% (except high RH) in the morning and then gradually decreased by 19-68% in the afternoon. This dynamic change in light absorption of wood burning OC can be explained by two mechanisms: chromophore formation and sunlight bleaching. To investigate the effect of chemical transformation on light absorption, wood smoke particles were characterized using various spectrometers. The intensity of fluorescence, which is mainly related to polycyclic aromatic hydrocarbons (PAHs), rapidly decreased with time indicating the potential bleaching of PAHs. A decline of levoglucosan concentrations evinced the change of POA with time. The aerosol water content measured by Fourier transform infrared spectroscopy showed that wood burning aerosol became less hygroscopic as photooxidation proceeded. A similar trend in light absorption changes has been observed in ambient smoke aerosol originating from the 2012 County Line Wildfire in Florida. We conclude that the biomass burning OC becomes less light absorbing after 8-9 h sunlight exposure compared to fresh wood burning OC.

  20. Dynamic light absorption of biomass-burning organic carbon photochemically aged under natural sunlight

    NASA Astrophysics Data System (ADS)

    Zhong, M.; Jang, M.

    2014-02-01

    Wood-burning aerosol produced under smoldering conditions was photochemically aged with different relative humidity (RH) and NOx conditions using a 104 m3 dual outdoor chamber under natural sunlight. Light absorption of organic carbon (OC) was measured over the course of photooxidation using a UV-visible spectrometer connected to an integrating sphere. At high RH, the color decayed rapidly. NOx slightly prolonged the color of wood smoke, suggesting that NOx promotes the formation of chromophores via secondary processes. Overall, the mass absorption cross section (integrated between 280 and 600 nm) of OC increased by 11-54% (except high RH) in the morning and then gradually decreased by 19-68% in the afternoon. This dynamic change in light absorption of wood-burning OC can be explained by two mechanisms: chromophore formation and sunlight bleaching. To investigate the effect of chemical transformation on light absorption, wood smoke particles were characterized using various spectrometers. The intensity of fluorescence, which is mainly related to polycyclic aromatic hydrocarbons (PAHs), rapidly decreased with time, indicating the potential bleaching of PAHs. A decline of levoglucosan concentrations evinced the change of primary organic aerosol with time. The aerosol water content measured by Fourier transform infrared spectroscopy showed that wood-burning aerosol became less hygroscopic as photooxidation proceeded. A similar trend in light absorption changes has been observed in ambient smoke aerosol originating from the 2012 County Line wildfire in Florida. We conclude that the biomass-burning OC becomes less light absorbing after 8-9 h sunlight exposure compared to fresh wood-burning OC.

  1. Evaluation of Airborne Visible/Infrared Imaging Spectrometer Data of the Mountain Pass, California carbonatite complex

    NASA Technical Reports Server (NTRS)

    Crowley, James; Rowan, Lawrence; Podwysocki, Melvin; Meyer, David

    1988-01-01

    Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data of the Mountain Pass, California carbonatite complex were examined to evaluate the AVIRIS instrument performance and to explore alternative methods of data calibration. Although signal-to-noise estimates derived from the data indicated that the A, B, and C spectrometers generally met the original instrument design objectives, the S/N performance of the D spectrometer was below expectations. Signal-to-noise values of 20 to 1 or lower were typical of the D spectrometer and several detectors in the D spectrometer array were shown to have poor electronic stability. The AVIRIS data also exhibited periodic noise, and were occasionally subject to abrupt dark current offsets. Despite these limitations, a number of mineral absorption bands, including CO3, Al-OH, and unusual rare earth element bands, were observed for mine areas near the main carbonatite body. To discern these bands, two different calibration procedures were applied to remove atmospheric and solar components from the remote sensing data. The two procedures, referred to as the single spectrum and the flat field calibration methods gave distinctly different results. In principle, the single spectrum method should be more accurate; however, additional fieldwork is needed to rigorously determine the degree of calibration success.

  2. A short working distance multiple crystal x-ray spectrometer

    USGS Publications Warehouse

    Dickinson, B.; Seidler, G.T.; Webb, Z.W.; Bradley, J.A.; Nagle, K.P.; Heald, S.M.; Gordon, R.A.; Chou, I.-Ming

    2008-01-01

    For x-ray spot sizes of a few tens of microns or smaller, a millimeter-sized flat analyzer crystal placed ???1 cm from the sample will exhibit high energy resolution while subtending a collection solid angle comparable to that of a typical spherically bent crystal analyzer (SBCA) at much larger working distances. Based on this observation and a nonfocusing geometry for the analyzer optic, we have constructed and tested a short working distance (SWD) multicrystal x-ray spectrometer. This prototype instrument has a maximum effective collection solid angle of 0.14 sr, comparable to that of 17 SBCA at 1 m working distance. We find good agreement with prior work for measurements of the Mn K?? x-ray emission and resonant inelastic x-ray scattering for MnO, and also for measurements of the x-ray absorption near-edge structure for Dy metal using L??2 partial-fluorescence yield detection. We discuss future applications at third- and fourth-generation light sources. For concentrated samples, the extremely large collection angle of SWD spectrometers will permit collection of high-resolution x-ray emission spectra with a single pulse of the Linac Coherent Light Source. The range of applications of SWD spectrometers and traditional multi-SBCA instruments has some overlap, but also is significantly complementary. ?? 2008 American Institute of Physics.

  3. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1988-01-01

    Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments and earth-based radio astronomical observations can be used to infer abundances of microwave absorbing atmospheric constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. The key activity for this grant year has continued to be laboratory measurements of the microwave and millimeter-wave properties of the simulated atmospheres of the outer planets and their satellites. A Fabry-Perot spectrometer system capable of operation from 32 to 41 GHz was developed. Initially this spectrometer was used to complete laboratory measurements of the 7.5 to 9.3 mm absorption spectrum of ammonia. Laboratory measurements were begun at wavelengths near 3.2 mm, where a large number of observations of the emission from the outer planets were made. A description of this system is presented.

  4. Multidimensional spectrometer

    DOEpatents

    Zanni, Martin Thomas; Damrauer, Niels H.

    2010-07-20

    A multidimensional spectrometer for the infrared, visible, and ultraviolet regions of the electromagnetic spectrum, and a method for making multidimensional spectroscopic measurements in the infrared, visible, and ultraviolet regions of the electromagnetic spectrum. The multidimensional spectrometer facilitates measurements of inter- and intra-molecular interactions.

  5. Airborne & Ground-based measurements of atmospheric CO2 using the 1.57-μm laser absorption spectrometer

    NASA Astrophysics Data System (ADS)

    Sakaizawa, D.; Kawakami, S.; Nakajima, M.; Tanaka, T.; Miyamoto, Y.; Morino, I.; Uchino, O.; Asai, K.

    2009-12-01

    Greenhouse gases observing satellite (GOSAT) started the measurement of global CO2 abundances to reveal its continental inventory using two passive remote sensors. The goal that the sensor needs to be done is to achieve an 1% relative accuracy in order to reduce uncertainties of CO2 budget. Nevertheless, in the future global CO2 monitoring, more accurate measurement of global tropospheric CO2 abundances with the monthly regional scale are required to improve the knowledge of CO2 exchanges among the land, ocean, and atmosphere. In order to fulfill demands, a laser remote sensor, such as DIAL or laser absorption spectrometer (LAS), is a potential candidate of future space-based missions. Nowadays, those technologies are required to demonstrate an accuracy of the few-ppm level through airborne & ground-based measurements. We developed the prototype of the 1.57um LAS for a step of the next missions and perform it at the ground-based and airborne platform to show the properly validated performance in the framework of GOSAT validation. Our CO2 LAS is consisted of all optical fiber circuits & compact receiving /transmitting optics to achieve the portable, flexible and rigid system. The optical sources of on- and off-line are distributed feedback lasers, which are tuned at the strong and weak position of the R12 line in the (30012<-00001) absorption band. Their fiber coupled outputs are sinusoidal amplitude modulated by each EO devices with kHz rate and combined and amplified using an erbium doped fiber amplifier. Scattered signals from the hard target are collected by the 11cm receiving telescope and detected and stored into the laptop computer. After that, we evaluated the atmospheric CO2 density using the meteorological parameters and ratio between the on- and off-line signals. The resultant of the ground-based measurement of 3km optical length indicated that the statistical error of the path averaged atmospheric CO2 density is less than 2.8ppm with 25 minutes averaging

  6. Measurements of trace constituents from atmospheric infrared emission and absorption spectra, a feasibility study

    NASA Technical Reports Server (NTRS)

    Goldman, A.; Williams, W. J.; Murcray, D. G.

    1974-01-01

    The feasibility of detecting eight trace constituents (CH4, HCl, HF, HNO3, NH3, NO, NO2 and SO2) against the rest of the atmospheric background at various altitudes from infrared emission and absorption atmospheric spectra was studied. Line-by-line calculations and observational data were used to establish features that can be observed in the atmospheric spectrum due to each trace constituent. Model calculations were made for experimental conditions which approximately represent state of the art emission and absorption spectrometers.

  7. Miniaturized differential optical absorption spectroscopy (DOAS) system for the analysis of NO2

    NASA Astrophysics Data System (ADS)

    Morales, J. Alberto; Walsh, James E.; Treacy, Jack E.; Garland, Wendy E.

    2003-03-01

    Current trends in optical design engineering are leading to the development of new systems which can analyze atmospheric pollutants in a fast and easy way, allowing remote-sensing and miniaturization at a low cost. A small portable fiber-optic based system is presented for the spectroscopic analysis of a common gas pollutant, NO2. The novel optical set-up described consists of a small telescope that collects ultraviolet-visible light from a xenon lamp located 600 m away. The light is coupled into a portable diode array spectrometer through a fiber-optic cable and the system is controlled by a lap-top computer where the spectra are recorded. Using the spectrum of the lamp as a reference, the absorption spectrum of the open path between the lamp and the telescope is calculated. Known absorption features in the NO2 spectrum are used to calculate the concentration of the pollutant using the principles of Differential Optical Absorption Spectroscopy (DOAS). Calibration is carried by using sample gas bags of known concentration of the pollutant. The results obtained demonstrate that it is possible to detect and determine NO2 concentrations directly from the atmosphere at typical environment levels by using an inexpensive field based fiber-optic spectrometer system.

  8. The SPEDE spectrometer

    NASA Astrophysics Data System (ADS)

    Papadakis, P.; Cox, D. M.; O'Neill, G. G.; Borge, M. J. G.; Butler, P. A.; Gaffney, L. P.; Greenlees, P. T.; Herzberg, R.-D.; Illana, A.; Joss, D. T.; Konki, J.; Kröll, T.; Ojala, J.; Page, R. D.; Rahkila, P.; Ranttila, K.; Thornhill, J.; Tuunanen, J.; Van Duppen, P.; Warr, N.; Pakarinen, J.

    2018-03-01

    The electron spectrometer, SPEDE, has been developed and will be employed in conjunction with the Miniball spectrometer at the HIE-ISOLDE facility, CERN. SPEDE allows for direct measurement of internal conversion electrons emitted in-flight, without employing magnetic fields to transport or momentum filter the electrons. Together with the Miniball spectrometer, it enables simultaneous observation of γ rays and conversion electrons in Coulomb excitation experiments using radioactive ion beams.

  9. Ultrasensitive, self-calibrated cavity ring-down spectrometer for quantitative trace gas analysis.

    PubMed

    Chen, Bing; Sun, Yu R; Zhou, Ze-Yi; Chen, Jian; Liu, An-Wen; Hu, Shui-Ming

    2014-11-10

    A cavity ring-down spectrometer is built for trace gas detection using telecom distributed feedback (DFB) diode lasers. The longitudinal modes of the ring-down cavity are used as frequency markers without active-locking either the laser or the high-finesse cavity. A control scheme is applied to scan the DFB laser frequency, matching the cavity modes one by one in sequence and resulting in a correct index at each recorded spectral data point, which allows us to calibrate the spectrum with a relative frequency precision of 0.06 MHz. Besides the frequency precision of the spectrometer, a sensitivity (noise-equivalent absorption) of 4×10-11  cm-1  Hz-1/2 has also been demonstrated. A minimum detectable absorption coefficient of 5×10-12  cm-1 has been obtained by averaging about 100 spectra recorded in 2  h. The quantitative accuracy is tested by measuring the CO2 concentrations in N2 samples prepared by the gravimetric method, and the relative deviation is less than 0.3%. The trace detection capability is demonstrated by detecting CO2 of ppbv-level concentrations in a high-purity nitrogen gas sample. Simple structure, high sensitivity, and good accuracy make the instrument very suitable for quantitative trace gas analysis.

  10. Emission and absorption x-ray edges of Li

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

    Callcott, T A; Arakawa, E T; Ederer, D L

    1977-01-01

    Measurements of the K X-ray absorption and emission edges of Li are reported. They were made with the same spectrometer at the NBS storage ring and serve to establish a 0.1 eV separation between the edges with no possibility of instrument calibration error. These results are compared with recent theories of Almbladh and Mahan describing the effects of incomplete phonon relaxation about the core hole. It is concluded that these theories give a satisfactory explanation of the data.

  11. Infrared absorption cross sections of alternative CFCs

    NASA Technical Reports Server (NTRS)

    Clerbaux, Cathy; Colin, Reginald; Simon, Paul C.

    1994-01-01

    Absorption cross sections have obtained in the infrared atmospheric window, between 600 and 1500 cm(exp -1), for 10 alternative hydrohalocarbons: HCFC-22, HCFC-123, HCFC-124, HCFC-141b, HCFC-142b, HCFC-225ca, HCFC-225cb, HFC-125, HFC-134a, and HFC-152a. The measurements were made at three temperatures (287K, 270K and 253K) with a Fourier transform spectrometer operating at 0.03 cm(exp -1) apodized resolution. Integrated cross sections are also derived for use in radiative models to calculate the global warming potentials.

  12. A miniaturized near infrared spectrometer for non-invasive sensing of bio-markers as a wearable healthcare solution

    NASA Astrophysics Data System (ADS)

    Bae, Jungmok; Druzhin, Vladislav V.; Anikanov, Alexey G.; Afanasyev, Sergey V.; Shchekin, Alexey; Medvedev, Anton S.; Morozov, Alexander V.; Kim, Dongho; Kim, Sang Kyu; Moon, Hyunseok; Jang, Hyeongseok; Shim, Jaewook; Park, Jongae

    2017-02-01

    A novel miniaturized near-infrared spectrometer readily mountable to wearable devices for continuous monitoring of individual's key bio-markers was proposed. Spectrum is measured by sequential illuminations with LED's, having independent spectrum profiles and a continuous detection of light radiations from the skin tissue with a single cell PD. Based on Tikhonov regularization with singular value decomposition, a spectrum resolution less than 10nm was reconstructed based on experimentally measured LED profiles. A prototype covering first overtone band (1500-1800nm) where bio-markers have pronounced absorption peaks was fabricated and verified of its performance. Reconstructed spectrum shows that the novel concept of miniaturized spectrometer is valid.

  13. Stratospheric ozone measurement with an infrared heterodyne spectrometer

    NASA Technical Reports Server (NTRS)

    Abbas, M. M.; Kostiuk, T.; Mumma, M. J.; Buhl, D.; Kunde, V. G.; Brown, L. W.; Spears, D.

    1978-01-01

    A stratospheric ozone absorption line in the 10 micron band was measured and resolved completely, using an infrared heterodyne spectrometer with a spectral resolution of 5 MHz. The vertical concentration profile of stratospheric ozone was obtained through an analytical inversion of the measured spectra line profile. The absolute total column density was 0.32 plus or minus 0.02 cm-atm with a peak mixing ratio occurring at approximately 24 km. The (7,1,6) - (7,1,7) O3 line center frequency was found to be 1043.1772 plus or minus 0.00033 cm/1 or 420 plus or minus 10 MHz higher than the P(24) CO2 laser line frequency.

  14. Stratospheric ozone measurement with an infrared heterodyne spectrometer

    NASA Technical Reports Server (NTRS)

    Abbas, M. M.; Kostiuk, T.; Mumma, M. J.; Buhl, D.; Kunde, V. G.; Brown, L. W.

    1978-01-01

    A stratospheric ozone absorption line in the 10 microns band was measured and resolved completely, using an infrared heterodyne spectrometer with spectral resolution of 5 MHz (0.000167 cm to -1 power). The vertical concentration profile of stratospheric ozone was obtained through an analytical inversion of the measured spectral line profile. The absolute total column density was 0.34 cm atm with a peak mixing ratio occurring at approximately 24 km. The (7,1,6) to (7,1,7) O3 line center frequency was found to be 1043.1775 + or - 0.00033 cm to toe -1 power, or 430 + or - 10 MHz higher than the P(24) CO2 laser line frequency.

  15. Millimeter-Wave Absorption as a Quality Control Tool for M-Type Hexaferrite Nanopowders

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

    McCloy, John S.; Korolev, Konstantin A.; Crum, Jarrod V.

    2013-01-01

    Millimeter wave (MMW) absorption measurements have been conducted on commercial samples of large (micrometer-sized) and small (nanometer-sized) particles of BaFe12O19 and SrFe12O19 using a quasi-optical MMW spectrometer and a series of backwards wave oscillators encompassing the 30-120 GHz range. Effective anisotropy of the particles calculated from the resonant absorption frequency indicates lower overall anisotropy in the nano-particles. Due to their high magnetocrystalline anisotropy, both BaFe12O19 and SrFe12O19 are expected to have spin resonances in the 45-55 GHz range. Several of the sampled BaFe12O19 powders did not have MMW absorptions, so they were further investigated by DC magnetization and x-ray diffractionmore » to assess magnetic behavior and structure. The samples with absent MMW absorption contained primarily iron oxides, suggesting that MMW absorption could be used for quality control in hexaferrite powder manufacture.« less

  16. A prototype stationary Fourier transform spectrometer for near-infrared absorption spectroscopy.

    PubMed

    Li, Jinyang; Lu, Dan-feng; Qi, Zhi-mei

    2015-09-01

    A prototype stationary Fourier transform spectrometer (FTS) was constructed with a fiber-coupled lithium niobate (LiNbO3) waveguide Mach-Zehnder interferometer (MZI) for the purpose of rapid on-site spectroscopy of biological and chemical measurands. The MZI contains push-pull electrodes for electro-optic modulation, and its interferogram as a plot of intensity against voltage was obtained by scanning the modulating voltage from -60 to +60 V in 50 ms. The power spectrum of input signal was retrieved by Fourier transform processing of the interferogram combined with the wavelength dispersion of half-wave voltage determined for the MZI used. The prototype FTS operates in the single-mode wavelength range from 1200 to 1700 nm and allows for reproducible spectroscopy. A linear concentration dependence of the absorbance at λmax = 1451 nm for water in ethanolic solution was obtained using the prototype FTS. The near-infrared spectroscopy of solid samples was also implemented, and the different spectra obtained with different materials evidenced the chemical recognition capability of the prototype FTS. To make this prototype FTS practically applicable, work on improving its spectral resolution by increasing the maximum optical path length difference is in progress.

  17. A survey of ultraviolet interstellar absorption lines

    NASA Technical Reports Server (NTRS)

    Bohlin, R. C.; Jenkins, E. B.; Spitzer, L., Jr.; York, D. G.; Hill, J. K.; Savage, B. D.; Snow, T. P., Jr.

    1983-01-01

    A telescope-spectrometer on the Copernicus spacecraft made possible the measurement of many ultraviolet absorption lines produced by the interstellar gas. The present survey provides data on ultraviolet absorption lines in the spectra of 88 early-type stars. The stars observed are divided into four classes, including reddened stars, unreddened bright stars, moderately reddened bright stars, and unreddened and moderately reddened faint stars. Data are presented for equivalent width, W, radial velocity V, and rms line width, D, taking into account some 10 to 20 lines of N I, O I, Si II, P II, S II, Cl I, Cl II, Mn II, Fe II, Ni II, Cu II, and H2. The data are based on multiple scans for each line. Attention is given to details of observations, the data reduction procedure, and the computation of equivalent width, mean velocity, and velocity dispersion.

  18. Intercomparison of six ambient [CH2O] measurement techniques

    NASA Astrophysics Data System (ADS)

    Gilpin, Tim; Apel, Eric; Fried, Alan; Wert, Bryan; Calvert, Jack; Genfa, Zhang; Dasgupta, Purnendu; Harder, Jerry W.; Heikes, Brian; Hopkins, Brian; Westberg, Hal; Kleindienst, Tad; Lee, Yin-Nan; Zhou, Xianliang; Lonneman, William; Sewell, Scott

    1997-09-01

    From May 29 to June 3, 1995 a blind intercomparison of six ambient formaldehyde measurement techniques took place at a field site near the National Center for Atmospheric Research in Boulder, Colorado. The continuous measurement methods intercompared were tunable diode laser absorption spectroscopy, (TDLAS); coil/2,4-dinitrophenylhydrazine, (CDNPH); 1,3-cyclohexanedione-diffusion scrubber (CHDDS); and the coil enzyme method (CENZ). In addition, two different cartridge methods were compared: silica gel-2,4-dinitrophenylhydrazine (DPNH) systems and a C-18-DNPH system. The intercomparison was conducted with spiked zero air (part 1) and ambient air (part 2). The CH2O standards for part 1 were calibrated by several independent methods and delivered to participants via a common glass manifold with potential trace gas interférants common to ambient air (O3, SO2, NO2, isoprene, H2O). The TDLAS system was used to confirm the absolute accuracy of the standards and served as a mission reference for part 1. The ambient phase lasted 44 hours with all participants sampling from a common glass tower. Differences between the ambient [CH2O] observed by the TDLAS and the other continuous methods were significant in some cases. For matched ambient measurement times the average ratios (±1σ) [CH2O]measured/[CH2O]TDLAS were: 0.89±0.12 (CDNPH); 1.30±0.02 (CHDDS); 0.63±0.03 (CENZ). The methods showed similar variations but different absolute values and the divergences appeared to result largely from calibration differences (no gas phase standards were used by groups other than NCAR). When the regressions of the participant [CH2O] values versus the TDLAS values, (measured in part 1), were used to normalize all of the results to the common gas phase standards of the NCAR group, the average ratios (±1σ), [CH2O]corrected/[CH2O]TDLAS for the first measurement period were much closer to unity: 1.04±0.14 (CDNPH), 1.00±0.11 (CHDDS), and 0.82±0.08 (CENZ). With the continuous methods

  19. A survey of local interstellar hydrogen from OAO-2 observations of Lyman alpha absorption

    NASA Technical Reports Server (NTRS)

    Savage, B. D.; Jenkins, E. B.

    1972-01-01

    The Wisconsin far ultraviolet spectrometer aboard OAO-2 observed the wavelength region near 1216 A for 69 stars of spectral type B2 or earlier. From the strength of the observed interstellar L sub alpha absorption, atomic hydrogen column densities were derived over distances averaging 300 pc away from the sun. The OAO data were compared to synthetic ultraviolet spectra, originally derived from earlier higher resolution rocket observations, which were computer processed to simulate the effects of absorption by different amounts of hydrogen followed by the instrumental blending.

  20. Bulk and integrated acousto-optic spectrometers for molecular astronomy with heterodyne spectrometers

    NASA Technical Reports Server (NTRS)

    Chin, G.; Buhl, D.; Florez, J. M.

    1981-01-01

    A survey of acousto-optic spectrometers for molecular astronomy is presented, noting a technique of combining the acoustic bending of a collimated coherent light beam with a Bragg cell followed by an array of sensitive photodetectors. This acousto-optic spectrometer has a large bandwidth, a large number of channels, high resolution, and is energy efficient. Receiver development has concentrated on high-frequency heterodyne systems for the study of the chemical composition of the interstellar medium. RF spectrometers employing acousto-optic diffraction cells are described. Acousto-optic techniques have been suggested for applications to electronic warfare, electronic countermeasures and electronic support systems. Plans to use integrated optics for the further miniaturization of acousto-optic spectrometers are described. Bulk acousto-optic spectrometers with 300 MHz and 1 GHz bandwidths are being developed for use in the back-end of high-frequency heterodyne receivers for astronomical research.

  1. Superconducting High Energy Resolution Gamma-ray Spectrometers

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

    Chow, D T

    2002-02-22

    We have demonstrated that a bulk absorber coupled to a TES can serve as a good gamma-ray spectrometer. Our measured energy resolution of 70 eV at 60 keV is among the best measurements in this field. We have also shown excellent agreement between the noise predictions and measured noise. Despite this good result, we noted that our detector design has shortcomings with a low count rate and vulnerabilities with the linearity of energy response. We addressed these issues by implementation of an active negative feedback bias. We demonstrated the effects of active bias such as additional pulse shortening, reduction ofmore » TES change in temperature during a pulse, and linearization of energy response at low energy. Linearization at higher energy is possible with optimized heat capacities and thermal conductivities of the microcalorimeter. However, the current fabrication process has low control and repeatability over the thermal properties. Thus, optimization of the detector performance is difficult until the fabrication process is improved. Currently, several efforts are underway to better control the fabrication of our gamma-ray spectrometers. We are developing a full-wafer process to produce TES films. We are investigating the thermal conductivity and surface roughness of thicker SiN membranes. We are exploring alternative methods to couple the absorber to the TES film for reproducibility. We are also optimizing the thermal conductivities within the detector to minimize two-element phonon noise. We are experimenting with different absorber materials to optimize absorption efficiency and heat capacity. We are also working on minimizing Johnson noise from the E S shunt and SQUID amplifier noise. We have shown that our performance, noise, and active bias models agree very well with measured data from several microcalorimeters. Once the fabrication improvements have been implemented, we have no doubt that our gamma-ray spectrometer will achieve even more spectacular

  2. Simple system for measuring tritium Ad/absorption using a 2. pi. counter and thermal desorption spectrometer

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

    Miyake, H.; Matsuyama, M.; Watanabe, K.

    1992-03-01

    In this paper, the authors develop a simple system using tritium tracer and thermal desorption techniques to measure the tritium adsorption and/or absorption on/in a material having typical surface conditions: namely, not cleaned surface. The tritium counting devices used were a 2{pi} counter and conventional proportional counter. With this system, the amounts of ad/absorption could be measured without exposing the samples to air after exposing them to tritium gas. The overall efficiency (F) of the 2{pi} counter was described at F = exp({minus}2.64h), where h is the distance from the sample to the detector. Ad/absorption measurements were carried out formore » several materials used for fabricating conventional vacuum systems. The results were, in the order of decreasing amounts of ad/absorption, as (fiber reinforced plastics(FRP)) {gt} (nickel(Ni), molybdenum disulfide(MoS{sub 2})) {gt} (stainless steel (SS304), iron(Fe), aluminum alloy(A2219)) {gt} (boron nitride(h-BN), silicon carbide (SiC), SS304 passivated by anodic oxidation layers(ASS) and that by boron nitride segregation layers (BSS)). The relative amounts were abut 100 for Ni and 0.1 for ASS and BSS, being normalized to Fe = 1.« less

  3. Interstellar X-Ray Absorption Spectroscopy of the Crab Pulsar with the LETGS

    NASA Technical Reports Server (NTRS)

    Paerels, Frits; Weisskopf, Martin C.; Tennant, Allyn F.; ODell, Stephen L.; Swartz, Douglas A.; Kahn, Steven M.; Behar, Ehud; Becker, Werner; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    We study the interstellar X-ray absorption along the line of sight to the Crab Pulsar. The Crab was observed with the Low Energy Transmission Grating Spectrometer on the Chandra X-ray Observatory, and the pulsar, a point source, produces a full resolution spectrum. The continuum spectrum appears smooth, and we compare its parameters with other measurements of the pulsar spectrum. The spectrum clearly shows absorption edges due to interstellar Ne, Fe, and O. The O edge shows spectral structure that is probably due to O bound in molecules or dust. We search for near-edge structure (EXAFS) in the O absorption spectrum. The Fe L absorption spectrum is largely due to a set of unresolved discrete n=2-3 transitions in neutral or near-neutral Fe, and we analyze it using a new set of dedicated atomic structure calculations, which provide absolute cross sections. In addition to being interesting in its own right, the ISM absorption needs to be understood in quantitative detail in order to derive spectroscopic constraints on possible soft thermal radiation from the pulsar.

  4. A seven-crystal Johann-type hard x-ray spectrometer at the Stanford Synchrotron Radiation Lightsource

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

    Sokaras, D.; Weng, T.-C.; Nordlund, D.

    2013-05-15

    We present a multicrystal Johann-type hard x-ray spectrometer ({approx}5-18 keV) recently developed, installed, and operated at the Stanford Synchrotron Radiation Lightsource. The instrument is set at the wiggler beamline 6-2 equipped with two liquid nitrogen cooled monochromators - Si(111) and Si(311) - as well as collimating and focusing optics. The spectrometer consists of seven spherically bent crystal analyzers placed on intersecting vertical Rowland circles of 1 m of diameter. The spectrometer is scanned vertically capturing an extended backscattering Bragg angular range (88 Degree-Sign -74 Degree-Sign ) while maintaining all crystals on the Rowland circle trace. The instrument operates in atmosphericmore » pressure by means of a helium bag and when all the seven crystals are used (100 mm of projected diameter each), has a solid angle of about 0.45% of 4{pi} sr. The typical resolving power is in the order of (E/{Delta}E){approx}10 000. The spectrometer's high detection efficiency combined with the beamline 6-2 characteristics permits routine studies of x-ray emission, high energy resolution fluorescence detected x-ray absorption and resonant inelastic x-ray scattering of very diluted samples as well as implementation of demanding in situ environments.« less

  5. Compact Infrared Spectrometers

    NASA Technical Reports Server (NTRS)

    Mouroulis, Pantazis

    2009-01-01

    Concentric spectrometer forms are advantageous for constructing a variety of systems spanning the entire visible to infrared range. Spectrometer examples are given, including broadband or high resolution forms. Some issues associated with the Dyson catadioptric type are also discussed.

  6. Detection of spectral line curvature in imaging spectrometer data

    NASA Astrophysics Data System (ADS)

    Neville, Robert A.; Sun, Lixin; Staenz, Karl

    2003-09-01

    A procedure has been developed to measure the band-centers and bandwidths for imaging spectrometers using data acquired by the sensor in flight. This is done for each across-track pixel, thus allowing the measurement of the instrument's slit curvature or spectral 'smile'. The procedure uses spectral features present in the at-sensor radiance which are common to all pixels in the scene. These are principally atmospheric absorption lines. The band-center and bandwidth determinations are made by correlating the sensor measured radiance with a modelled radiance, the latter calculated using MODTRAN 4.2. Measurements have been made for a number of instruments including Airborne Visible and Infra-Red Imaging Spectrometer (AVIRIS), SWIR Full Spectrum Imager (SFSI), and Hyperion. The measurements on AVIRIS data were performed as a test of the procedure; since AVIRIS is a whisk-broom scanner it is expected to be free of spectral smile. SFSI is an airborne pushbroom instrument with considerable spectral smile. Hyperion is a satellite pushbroom sensor with a relatively small degree of smile. Measurements of Hyperion were made using three different data sets to check for temporal variations.

  7. Absorption coefficients of solid NH3 from 50 to 7000 per cm

    NASA Technical Reports Server (NTRS)

    Sill, G.; Fink, U.; Ferraro, J. R.

    1980-01-01

    Thin-film spectra of solid NH3 at a resolution of 1 per cm were used to determine its absorption coefficient over the range 50-7000 per cm. The thin films were formed inside a liquid N2 cooled dewar using a variety of substrates and dewar windows. The spectra were recorded with two Fourier spectrometers, one covering the range from 1 to 4 microns and the other from 2.6 to 200 microns. The thickness of the films was measured with a laser interference technique. The absorption coefficients were determined by application of Lambert's law and by a fitting procedure to the observed spectra using thin-film theory. Good agreement was found with the absorption coefficients recently determined by other investigators over a more restricted wavelength range. A metastable phase was observed near a temperature of 90 K and its absorption coefficient is reported. No other major spectral changes with temperature were noted for the range 88-120 K.

  8. Search for molecular absorptions with the Fourier Transform Spectrometer

    NASA Technical Reports Server (NTRS)

    Knacke, Roger F.

    1995-01-01

    The objective of this research was a search for water molecules in the gas phase in molecular clouds. Water should be among the most abundant gases in the clouds and is of fundamental importance in gas chemistry, cloud cooling, shock wave chemistry, and gas-grain interactions of interstellar dust. Detection of water in Comet Halley in the 2.7 micron v(3) band in 1986 had shown that airborne H2O observations are feasible (ground-based observations of H2O are impossible because of the massive water content of the atmosphere). We planned to observe the v(3) band in interstellar clouds where a number of lines of this band should be in absorption. The search for H2O commenced in 1988 with a two flight program on the KAO. this resulted in a detection of interstellar H2O with S/N of 2-4 in the v(3) 1(01)-2(02) line at 3801.42/cm. A subsequent flight series of two flights in 1989 resulted in confirmation to the 3801.42/cm line detection and the detection of altogether four strong lines in the 000-001 v(3) vibration-rotation band of H2O.

  9. Development of a diode laser heterodyne spectrometer and observations of silicon monoxide in sunspots. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Glenar, D. A.

    1981-01-01

    A state of the art, tunable diode laser infrared heterodyne spectrometer was designed and constructed for ground based observations throughout the 8 to 12 micron atmospheric window. The instrument was optimized for use with presently available tunable diode lasers, and was designed as a flexible field system for use with large reflecting telescopes. The instrument was aligned and calibrated using laboratory and astronomical sources. Observations of SiO fundamental (v = 1-0) and hot band (v = 2-1) absorption features were made in sunspots near 8 microns using the spectrometer. The data permit an unambiguous determination of the temperature pressure relation in the upper layers of the umbral atmosphere, and support the sunspot model suggested by Stellmacher and Wiehr.

  10. Using a portable terahertz spectrometer to measure the optical properties of in vivo human skin

    NASA Astrophysics Data System (ADS)

    Echchgadda, Ibtissam; Grundt, Jessica A.; Tarango, Melissa; Ibey, Bennett L.; Tongue, Thomas; Liang, Min; Xin, Hao; Wilmink, Gerald J.

    2013-12-01

    Terahertz (THz) time-domain spectroscopy systems permit the measurement of a tissue's hydration level. This feature makes THz spectrometers excellent tools for the noninvasive assessment of skin; however, current systems are large, heavy and not ideal for clinical settings. We previously demonstrated that a portable, compact THz spectrometer permitted measurement of porcine skin optical properties that were comparable to those collected with conventional systems. In order to move toward human use of this system, the goal for this study was to measure the absorption coefficient (μa) and index of refraction (n) of human subjects in vivo. Spectra were collected from 0.1 to 2 THz, and measurements were made from skin at three sites: the palm, ventral and dorsal forearm. Additionally, we used a multiprobe adapter system to measure each subject's skin hydration levels, transepidermal water loss, and melanin concentration. Our results suggest that the measured optical properties varied considerably for skin tissues that exhibited dissimilar hydration levels. These data provide a framework for using compact THz spectrometers for clinical applications.

  11. Note: Vector network analyzer-ferromagnetic resonance spectrometer using high Q-factor cavity.

    PubMed

    Lo, C K; Lai, W C; Cheng, J C

    2011-08-01

    A ferromagnetic resonance (FMR) spectrometer whose main components consist of an X-band resonator and a vector network analyzer (VNA) was developed. This spectrometer takes advantage of a high Q-factor (9600) cavity and state-of-the-art VNA. Accordingly, field modulation lock-in technique for signal to noise ratio (SNR) enhancement is no longer necessary, and FMR absorption can therefore be extracted directly. Its derivative for the ascertainment of full width at half maximum height of FMR peak can be found by taking the differentiation of original data. This system was characterized with different thicknesses of permalloy (Py) films and its multilayer, and found that the SNR of 5 nm Py on glass was better than 50, and did not have significant reduction even at low microwave excitation power (-20 dBm), and at low Q-factor (3000). The FMR other than X-band can also be examined in the same manner by using a suitable band cavity within the frequency range of VNA.

  12. Multi-Wavelength Measurement of Bus Exhausts Using a Four QC Laser Spectrometer

    NASA Astrophysics Data System (ADS)

    Hay, K. G.; Wilson, D.; Duxbury, G.; Langford, N.

    2010-06-01

    Using a portable, lightweight, four laser intra-pulse quantum cascade laser spectrometer we have measured the variation of the composition of exhaust gases emitted by diesel engined buses which are representative of the decades from the 1930's until the 1990's. The lasers and the fast detector used in the spectrometer are Peltier cooled, and the spectra are recorded using each laser in turn, in a repeated four laser cycle. The instrument is controlled via a ruggedised laptop computer. The wavelengths of the lasers used were 7.84 microns (methane, nitrous oxide and formaldehyde), 6.13 microns (nitrogen dioxide) 5.25 microns (nitric oxide and water) and 4.88 microns (carbon monoxide and carbon dioxide). The path length of the multiple pass absorption cell used was 77 m. The results we will present demonstrate the possibility of deploying this type of instrument for investigating gas emissions from a variety of sources.

  13. 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.

  14. Low-cost 3D printed 1  nm resolution smartphone sensor-based spectrometer: instrument design and application in ultraviolet spectroscopy.

    PubMed

    Wilkes, Thomas C; McGonigle, Andrew J S; Willmott, Jon R; Pering, Tom D; Cook, Joseph M

    2017-11-01

    We report on the development of a low-cost spectrometer, based on off-the-shelf optical components, a 3D printed housing, and a modified Raspberry Pi camera module. With a bandwidth and spectral resolution of ≈60  nm and 1 nm, respectively, this device was designed for ultraviolet (UV) remote sensing of atmospheric sulphur dioxide (SO 2 ), ≈310  nm. To the best of our knowledge, this is the first report of both a UV spectrometer and a nanometer resolution spectrometer based on smartphone sensor technology. The device performance was assessed and validated by measuring column amounts of SO 2 within quartz cells with a differential optical absorption spectroscopy processing routine. This system could easily be reconfigured to cover other UV-visible-near-infrared spectral regions, as well as alternate spectral ranges and/or linewidths. Hence, our intention is also to highlight how this framework could be applied to build bespoke, low-cost, spectrometers for a range of scientific applications.

  15. Laser spectrometer for CO2 clumped isotope analysis

    NASA Astrophysics Data System (ADS)

    Prokhorov, Ivan; Kluge, Tobias; Janssen, Christof

    2017-04-01

    Carbon dioxide clumped isotope thermometry has proven to be a reliable method for biogeochemical and atmospheric research. We present a new laser spectroscopic instrument for doubly-substituted isotopologues analysis. In contrast to a conventional isotope ratio mass spectrometry (IRMS), tunable laser direct absorption spectroscopy (TLDAS) has the advantage of isotopologue-specific determination free of isobaric interferences. Tunable infrared laser based spectrometer for clumped isotope analysis is being developed in collaboration between Heidelberg University, Germany, and LERMA-IPSL, CNRS, France. The instrument employs two continuous intraband cascade lasers (ICL) tuned at 4439 and 4329 nm. The spectral windows covered by the lasers contain absorption lines of the six most abundant CO2 isotopologues, including the two doubly substituted species 16O13C18O and 16O13C17O, and all singly substituted isotopologues with 13C, 18O and 17O. A Herriott-type multi-pass cell provides two different absorption pathlengths to compensate the abundance difference between singly- and doubly-substituted isotopologues. We have reached the sub-permill precision required for clumped isotope measurements within the integration time of several seconds. The test version of the instrument demonstrates a performance comparable to state of the art IRMS. We highlight the following features of the instrument that are strong advantages compared to conventional mass spectrometry: measurement cycle in the minute range, simplified sample preparation routine, table-top layout with a potential for in-situ applications.

  16. Dual-wavelength dual-cavity spectrometer for NO2 detection in the presence of aerosol interference

    NASA Astrophysics Data System (ADS)

    Chandran, Satheesh; Puthukkudy, Anin; Varma, Ravi

    2017-07-01

    Precise determination of concentration of gases, such as NO2, in urban atmosphere is crucial in studying chemical reactions leading to secondary pollutants. In this study, a novel and sensitive yet simple and cost effective spectrometer was developed where two laser wavelengths and two parallel identical optical cavities were used. Monitoring of NO2 even in the presence of aerosol spectral interference was demonstrated. The intensity transmitted through one cavity, evacuated to 0.1 mbar, was designated as the reference signal ( I 0) while that through the other cavity, sampling air at atmospheric pressure, was designated as sample signal ( I). Quasi-simultaneous measurements of these I 0 and I were done for both laser wavelengths sequentially: one at 406.4 nm near the peak of the largest electronic transition of NO2 and the other at 446.9 nm, away from the peak yet exhibiting significant absorption. The addition of the second wavelength where NO2 has absorption was to ascertain the presence of aerosol scattering and compensate for it. Aerosol extinctions at both operating wavelengths were assumed to be the same, their ratio taken as unity for simplicity, and aerosol light extinction was retrieved. The spectrometer with average sampling interval of 5 s exhibited detection sensitivity of low parts per billion concentrations.

  17. 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.

  18. Tunable Diode Laser Absorption Spectroscopy Sensor for Calibration Free Humidity Measurements in Pure Methane and Low CO2 Natural Gas.

    PubMed

    Nwaboh, Javis Anyangwe; Pratzler, Sonja; Werhahn, Olav; Ebert, Volker

    2017-05-01

    We report a new direct tunable diode laser absorption spectroscopy (dTDLAS) sensor for absolute measurements of H 2 O in methane, ethane, propane, and low CO 2 natural gas. The sensor is operated with a 2.7 µm DFB laser, equipped with a high pressure single pass gas cell, and used to measure H 2 O amount of substance fractions in the range of 0.31-25 000 µmol/mol. Operating total gas pressures are up to 5000 hPa. The sensor has been characterized, addressing the traceability of the spectrometric results to the SI and the evaluation of the combined uncertainty, following the guide to the expression of uncertainty in measurement (GUM). The relative reproducibility of H 2 O amount of substance fraction measurements at 87 µmol/mol is 0.26% (0.23 µmol/mol). The maximum precision of the sensor was determined using a H 2 O in methane mixture, and found to be 40 nmol/mol for a time resolution of 100 s. This corresponds to a normalized detection limit of 330 nmol mol -1 ·m Hz -1/2 . The relative combined uncertainty of H 2 O amount fraction measurements delivered by the sensor is 1.2%.

  19. Improving Optical Absorption Models for Harsh Planetary Atmospheres: Laboratory Spectroscopy at Venus Surface Conditions

    NASA Astrophysics Data System (ADS)

    Cole, Ryan Kenneth; Schroeder, Paul James; Diego Draper, Anthony; Rieker, Gregory Brian

    2018-06-01

    Modelling absorption spectra in high pressure, high temperature environments is complicated by the increased relevance of higher order collisional phenomena (e.g. line mixing, collision-induced absorption, finite duration of collisions) that alter the spectral lineshape. Accurate reference spectroscopy in these conditions is of interest for mineralogy and radiative transfer studies of Venus as well as other dense planetary atmospheres. We present a new, high pressure, high temperature absorption spectroscopy facility at the University of Colorado Boulder. This facility employs a dual frequency comb absorption spectrometer to record broadband (500nm), high resolution (~0.002nm) spectra in conditions comparable to the Venus surface (730K, 90bar). Measurements of the near-infrared spectrum of carbon dioxide at high pressure and temperature will be compared to modeled spectra extrapolated from the HITRAN 2016 database as well as other published models that include additional collisional physics. This comparison gives insight into the effectiveness of existing absorption databases for modeling the lower Venus atmosphere as well as the need to expand absorption models to suit these conditions.

  20. Salts on Europa's surface detected by Galileo's near infrared mapping spectrometer

    USGS Publications Warehouse

    McCord, T.B.; Hansen, G.B.; Fanale, F.P.; Carlson, R.W.; Matson, D.L.; Johnson, T.V.; Smythe, W.D.; Crowley, J.K.; Martin, P.D.; Ocampo, A.; Hibbitts, C.A.; Granahan, J.C.

    1998-01-01

    Reflectance spectra in the 1- to 2.5-micrometer wavelength region of the surface of Europa obtained by Galileo's Near Infrared Mapping Spectrometer exhibit distorted water absorption bands that indicate the presence of hydrated minerals. The laboratory spectra of hydrated salt minerals such as magnesium sulfates and sodium carbonates and mixtures of these minerals provide a close match to the Europa spectra. The distorted bands are only observed in the optically darker areas of Europa, including the lineaments, and may represent evaporite deposits formed by water, rich in dissolved salts, reaching the surface from a water-rich layer underlying an ice crust.

  1. Balloon Borne Ultraviolet Spectrometer.

    DTIC Science & Technology

    1978-12-28

    n.c.aaary ond lden lfy by block numb.r) ultraviolet ground support equipment (GSE) spectrometers flight electronics instrumentation balloons \\ solar ...Assembly 4 Fig. 3 Solar Balloon Experiment Ass ’y 7 Fig. 4 Mechanical Interface , UV Spectrometer 8 Fig . 5 Spectrometer Body Assemb ly 10 Fig. 6...Diagram, GSE )bnitor 48 Selector and Battery Charger Fig. 25 Schematic Diagram, GSE Serial to 49 Parallel Data Converter Fig. 26 Schematic Diagram

  2. Terahertz Absorption and Circular Dichroism Spectroscopy of Solvated Biopolymers

    NASA Astrophysics Data System (ADS)

    Xu, Jing; Plaxco, Kevin; Allen, S. James

    2006-03-01

    Biopolymers are expected to exhibit broad spectral features in the terahertz frequency range, corresponding to their functionally relevant, global and sub-global collective vibrational modes with ˜ picosecond timescale. Recent advances in terahertz technology have stimulated researchers to employ terahertz absorption spectroscopy to directly probe these postulated collective modes. However, these pioneering studies have been limited to dry and, at best, moist samples. Successful isolation of low frequency vibrational activities of solvated biopolymers in their natural water environment has remained elusive, due to the overwhelming attenuation of the terahertz radiation by water. Here we have developed a terahertz absorption and circular dichroism spectrometer suitable for studying biopolymers in biologically relevant water solutions. We have precisely isolated, for the first time, the terahertz absorption of solvated prototypical proteins, Bovine Serum Albumin and Lysozyme, and made important direct comparison to the existing molecular dynamic simulations and normal mode calculations. We have also successfully demonstrated the magnetic circular dichroism in semiconductors, and placed upper bounds on the terahertz circular dichroism signatures of prototypical proteins in water solution.

  3. The absorption budget of fresh biomass burning aerosol from realistic laboratory fires

    NASA Astrophysics Data System (ADS)

    Wagner, N. L.; Adler, G. A.; Franchin, A.; Lamb, K.; Manfred, K.; Middlebrook, A. M.; Selimovic, V.; Schwarz, J. P.; Washenfelder, R. A.; Womack, C.; Yokelson, R. J.

    2017-12-01

    Wildfires are expected to increase globally due to climate change. The smoke from these wildfires has a highly uncertain radiative effect, largely due to the lack of detailed understanding of its optical properties. As part of the NOAA FIREX project, we have measured the optical properties of smoke primarily from laboratory burning of North American fuels at the Missoula Fire Sciences Laboratory. Here, we present a budget of the aerosol absorption from a portion of the laboratory fires. The total aerosol absorption was measured with photoacoustic spectrometers (PAS) at four wavelengths (405 nm, 532 nm, 660 nm, 870 nm) spanning the visible spectral region. The aerosol absorption is attributed to black carbon which absorbs broadly across the visible and ultraviolet (UV) spectral region and brown carbon (BrC) which absorbs in the blue and UV spectral regions. Then aerosol absorption measurements are compared with measurements of refractory black carbon (rBC) concentration by laser induced incandescence (SP2) and measurements of BrC concentration from a particle-into-liquid sampler coupled to a liquid absorption cell (BrC-PILS). Periodically, a thermodenuder was inserted upstream of all of the instruments to constrain the relationship between aerosol volatility and absorption. We synthesize these measurements to constrain the various contributors to total absorption including effects of lensing on rBC absorption, and of BrC that is not volatilized in the thermodenuder.

  4. Remote laser evaporative molecular absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Hughes, Gary B.; Lubin, Philip; Cohen, Alexander; Madajian, Jonathan; Kulkarni, Neeraj; Zhang, Qicheng; Griswold, Janelle; Brashears, Travis

    2016-09-01

    We describe a novel method for probing bulk molecular and atomic composition of solid targets from a distant vantage. A laser is used to melt and vaporize a spot on the target. With sufficient flux, the spot temperature rises rapidly, and evaporation of surface materials occurs. The melted spot creates a high-temperature blackbody source, and ejected material creates a plume of surface materials in front of the spot. Molecular and atomic absorption occurs as the blackbody radiation passes through the ejected plume. Bulk molecular and atomic composition of the surface material is investigated by using a spectrometer to view the heated spot through the ejected plume. The proposed method is distinct from current stand-off approaches to composition analysis, such as Laser-Induced Breakdown Spectroscopy (LIBS), which atomizes and ionizes target material and observes emission spectra to determine bulk atomic composition. Initial simulations of absorption profiles with laser heating show great promise for Remote Laser-Evaporative Molecular Absorption (R-LEMA) spectroscopy. The method is well-suited for exploration of cold solar system targets—asteroids, comets, planets, moons—such as from a spacecraft orbiting the target. Spatial composition maps could be created by scanning the surface. Applying the beam to a single spot continuously produces a borehole or trench, and shallow subsurface composition profiling is possible. This paper describes system concepts for implementing the proposed method to probe the bulk molecular composition of an asteroid from an orbiting spacecraft, including laser array, photovoltaic power, heating and ablation, plume characteristics, absorption, spectrometry and data management.

  5. Neutral Kaon Spectrometer 2

    NASA Astrophysics Data System (ADS)

    Kaneta, M.; Beckford, B.; Fujii, T.; Fujii, Y.; Futatsukawa, K.; Han, Y. C.; Hashimoto, O.; Hirose, K.; Ishikawa, T.; Kanda, H.; Kimura, C.; Maeda, K.; Nakamura, S. N.; Suzuki, K.; Tsukada, K.; Yamamoto, F.; Yamazaki, H.

    2018-04-01

    A large-acceptance spectrometer, Neutral Kaon Spectrometer 2 (NKS2), was newly constructed to explore various photoproduction reactions in the gigaelectronvolt region at the Laboratory of Nuclear Science (LNS, currently ELPH), Tohoku University. The spectrometer consisted of a dipole magnet, drift chambers, and plastic scintillation counters. NKS2 was designed to separate pions and protons in a momentum range of less than 1 GeV/ c, and was placed in a tagged photon beamline. A cryogenic H2/D2 target fitted to the spectrometer were designed. The design and performance of the detectors are described. The results of the NKS2 experiment on analyzing strangeness photoproduction data using a 0.8-1.1 GeV tagged photon beam are also presented.

  6. Fourier Transform Spectrometer System

    NASA Technical Reports Server (NTRS)

    Campbell, Joel F. (Inventor)

    2014-01-01

    A Fourier transform spectrometer (FTS) data acquisition system includes an FTS spectrometer that receives a spectral signal and a laser signal. The system further includes a wideband detector, which is in communication with the FTS spectrometer and receives the spectral signal and laser signal from the FTS spectrometer. The wideband detector produces a composite signal comprising the laser signal and the spectral signal. The system further comprises a converter in communication with the wideband detector to receive and digitize the composite signal. The system further includes a signal processing unit that receives the composite signal from the converter. The signal processing unit further filters the laser signal and the spectral signal from the composite signal and demodulates the laser signal, to produce velocity corrected spectral data.

  7. The Role of Convection in Redistributing Formaldehyde to the Upper Troposphere Over North America and the North Atlantic during the Summer 2004 INTEX Campaign

    NASA Technical Reports Server (NTRS)

    Fried, Alan; Olson, Jennifer R.; Walega, Jim; Crawford, Jim H.; Chen, Gao; Weibring, Petter; Richter, Dirk; Roller, Chad; Tittel, Frank; Porter, Michael; hide

    2007-01-01

    Measurements of CH2O from a tunable diode laser absorption spectrometer (TDLAS) were acquired onboard the NASA DC-8 during the summer 2004 INTEX-NA (Intercontinental Chemical Transport Experiment - North America) campaign to test our understanding of convection and production mechanisms in the upper troposphere (UT, 6-12-km) over continental North America and the North Atlantic Ocean. Point-by-point comparisons with box model calculations, when MHP (CH3OOH) measurements were available for model constraint, resulted in a median CH2O measurement/model ratio of 0.91 in the UT. Multiple tracers were used to arrive at a set of UT CH2O background and perturbed air mass periods, and 46% of the TDLAS measurements fell within the latter category. At least 66% to 73% of these elevated UT observations were caused by enhanced production from CH2O precursors rather than direct transport of CH2O from the boundary layer. This distinction is important, since the effects from the former can last for over a week or more compared to one day or less in the case of convective transport of CH2O itself. In general, production of CH2O from CH4 was found to be the dominant source term, even in perturbed air masses. This was followed by production from MHP, methanol, PAN type compounds, and ketones, in descending order of their contribution. In the presence of elevated NO from lightning and potentially from the stratosphere, there was a definite trend in the CH2O discrepancy, which for the highest NO mixing ratios produced a median CH2O measurement/model ratio of 3.9 in the 10-12-km range. Discrepancies in CH2O and HO2 in the UT with NO were highly correlated and this provided further information as to the possible mechanism(s) responsible. These discrepancies with NO are consistent with additional production sources of both gases involving CH3O2 + NO reactions, most likely caused by unmeasured hydrocarbons.

  8. Dual Etalon Cross Tilt Order Sorted Spectrometer (DECTOSS)

    NASA Astrophysics Data System (ADS)

    Kumer, John B.; Rairden, Richard L.; Mitchell, Keith E.; Roche, Aidan E.; Mergenthaler, John L.

    2002-11-01

    The Dual Etalon Cross Tilt Order Sorted Spectrometer (DECTOSS) uses relatively inexpensive off the shelf components in a small and simple package to provide ultra high spectral resolution over a limited spectral range. For example, the modest first try laboratory test setup DECTOSS we describe in this presentation achieves resolving power ~ 105 on a spectral range of about 1 nm centered near 760 nm. This ultra high spectral resolution facilitates some important atmospheric remote sensing applications including profiling cirrus and/or aerosol above bright reflective surfaces in the O2 A-band and the column measurements of CO and CO2 utilizing solar reflectance spectra. We show details of the how the use of ultra high spectral resolution in the O2 A-band improves the profiling of cirrus and aerosol. The DECTOSS utilizes a Narrow Band Spectral Filter (NBSF), a Low Resolution Etalon (LRE) and a High Resolution Etalon (HRE). Light passing through these elements is focused on to a 2 Dimensional Array Detector (2DAD). Off the shelf, solid etalons with airgap or solid spacer gap are used in this application. In its simplest application this setup utilizes a spatially uniform extended source so that spatial and spectral structure are not confused. In this presentation we'll show 2D spectral data obtained in a desktop test configuration, and in the first try laboratory test setup. These were obtained by illuminating a Lambertian screen with (1) monochromatic light, and (2) with atmospheric absorption spectra in the oxygen (O2) A-band. Extracting the 1D spectra from these data is a work in progress and we show preliminary results compared with (1) solar absorption data obtained with a large Echelle grating spectrometer, and (2) theoretical spectra. We point out areas for improvement in our laboratory test setup, and general improvements in spectral range and sensitivity that are planned for our next generation field test setup.

  9. Lunar orbital mass spectrometer experiment

    NASA Technical Reports Server (NTRS)

    Lord, W. P.

    1971-01-01

    The design, development, manufacture, test and calibration of five lunar orbital mass spectrometers with the four associated ground support equipment test sets are discussed. A mass spectrometer was installed in the Apollo 15 and one in the Apollo 16 Scientific Instrument Module within the Service Module. The Apollo 15 mass spectrometer was operated with collection of 38 hours of mass spectra data during lunar orbit and 50 hours of data were collected during transearth coast. The Apollo 16 mass spectrometer was operated with collection of 76 hours of mass spectra data during lunar orbit. However, the Apollo 16 mass spectrometer was ejected into lunar orbit upon malfunction of spacecraft boom system just prior to transearth insection and no transearth coast data was possible.

  10. Tropospheric and Airborne Emission Spectrometers

    NASA Technical Reports Server (NTRS)

    Glavich, Thomas; Beer, Reinhard

    1996-01-01

    X This paper describes the development of two related instruments, the Tropospheric Emission Spectrometer (TES) and the Airborne Emission Spectrometer (AES). Both instruments are infrared imaging Fourier Transform Spectrometers, used for measuring the state of the lower atmosphere, and in particular the measurement of ozone and ozone sources and sinks.

  11. The development and evaluation of airborne in situ N2O and CH4 sampling using a quantum cascade laser absorption spectrometer (QCLAS)

    NASA Astrophysics Data System (ADS)

    Pitt, J. R.; Le Breton, M.; Allen, G.; Percival, C. J.; Gallagher, M. W.; Bauguitte, S. J.-B.; O'Shea, S. J.; Muller, J. B. A.; Zahniser, M. S.; Pyle, J.; Palmer, P. I.

    2016-01-01

    Spectroscopic measurements of atmospheric N2O and CH4 mole fractions were made on board the FAAM (Facility for Airborne Atmospheric Measurements) large atmospheric research aircraft. We present details of the mid-infrared quantum cascade laser absorption spectrometer (QCLAS, Aerodyne Research Inc., USA) employed, including its configuration for airborne sampling, and evaluate its performance over 17 flights conducted during summer 2014. Two different methods of correcting for the influence of water vapour on the spectroscopic retrievals are compared and evaluated. A new in-flight calibration procedure to account for the observed sensitivity of the instrument to ambient pressure changes is described, and its impact on instrument performance is assessed. Test flight data linking this sensitivity to changes in cabin pressure are presented. Total 1σ uncertainties of 2.47 ppb for CH4 and 0.54 ppb for N2O are derived. We report a mean difference in 1 Hz CH4 mole fraction of 2.05 ppb (1σ = 5.85 ppb) between in-flight measurements made using the QCLAS and simultaneous measurements using a previously characterised Fast Greenhouse Gas Analyser (FGGA, Los Gatos Research, USA). Finally, a potential case study for the estimation of a regional N2O flux using a mass balance technique is identified, and the method for calculating such an estimate is outlined.

  12. The development and evaluation of airborne in situ N2O and CH4 sampling using a Quantum Cascade Laser Absorption Spectrometer (QCLAS)

    NASA Astrophysics Data System (ADS)

    Pitt, J. R.; Le Breton, M.; Allen, G.; Percival, C. J.; Gallagher, M. W.; Bauguitte, S. J.-B.; O'Shea, S. J.; Muller, J. B. A.; Zahniser, M. S.; Pyle, J.; Palmer, P. I.

    2015-08-01

    Spectroscopic measurements of atmospheric N2O and CH4 mole fractions were made on board the FAAM (Facility for Airborne Atmospheric Measurements) large Atmospheric Research Aircraft. We present details of the mid-IR Aerodyne Research Inc. Quantum Cascade Laser Absorption Spectrometer (QCLAS) employed, including its configuration for airborne sampling, and evaluate its performance over 17 flights conducted during summer 2014. Two different methods of correcting for the influence of water vapour on the spectroscopic retrievals are compared and evaluated. A new in-flight calibration procedure to account for the observed sensitivity of the instrument to ambient pressure changes is described, and its impact on instrument performance is assessed. Test flight data linking this sensitivity to changes in cabin pressure is presented. Total 1σ uncertainties of 1.81 ppb for CH4 and 0.35 ppb for N2O are derived. We report a mean difference in 1 Hz CH4 mole fraction of 2.05 ppb (1σ = 5.85 ppb) between in-flight measurements made using the QCLAS and simultaneous measurements using a previously characterised Los Gatos Research Fast Greenhouse Gas Analyser (FGGA). Finally, a potential case study for the estimation of a regional N2O flux using a mass balance technique is identified, and the method for calculating such an estimate is outlined.

  13. Electronics for a Spectrometer

    NASA Image and Video Library

    2014-01-24

    NASA has provided part of the electronics package for an instrument called the Double Focusing Mass Spectrometer, which is part of the Swiss-built Rosetta Orbiter Spectrometer for Ion and Neutral Analysis ROSINA instrument.

  14. First characterization of a static Fourier transform spectrometer

    NASA Astrophysics Data System (ADS)

    Lacan, A.; Bréon, F.-M.; Rosak, A.; Pierangelo, C.

    2017-11-01

    A new instrument concept for a Static Fourier Transform Spectrometer has been developed and characterized by CNES. This spectrometer is based on a Michelson interferometer concept, but a system of stepped mirrors generates all interference path differences simultaneously, without any moving parts. The instrument permits high spectral resolution measurements (≍0.1 cm-1) adapted to the sounding and the monitoring of atmospheric gases. Moreover, its overall dimensions are compatible with a micro satellite platform. The stepped mirrors are glued using a molecular bonding technique. An interference filter selects a waveband only a few nanometers wide. It limits the number of sampling points (and consequently the steps number) necessary to achieve the high resolution. The instrument concept can be optimized for the detection and the monitoring of various atmospheric constituents. CNES has developed a version whose measurements are centered on the CO2 absorption lines at 1573 nm (6357 cm-1). This model has a theoretical resolution of 40 pm (0.15 cm-1) within a 5 nm (22.5 cm-1) wide spectral window. It is aimed at the feasibility demonstration for atmospheric CO2 column measurements with a very demanding accuracy of better than 1%. Preliminary measurements indicate that, although high quality spectra are obtained, the theoretical performances are not yet achieved. We discuss the causes for the achieved performances and describe foreseen methods for their improvements.

  15. Absolute ozone absorption cross section in the Huggins Chappuis minimum (350-470 nm) at 296 K

    NASA Astrophysics Data System (ADS)

    Axson, J. L.; Washenfelder, R. A.; Kahan, T. F.; Young, C. J.; Vaida, V.; Brown, S. S.

    2011-11-01

    We report the ozone absolute absorption cross section between 350-470 nm, the minimum between the Huggins and Chappuis bands, where the ozone cross section is less than 10-22 cm2. Ozone spectra were acquired using an incoherent broadband cavity enhanced absorption spectrometer, with three channels centered at 365, 405, and 455 nm. The accuracy of the measured cross section is 4-30%, with the greatest uncertainty near the minimum absorption at 375-390 nm. Previous measurements vary by more than an order of magnitude in this spectral region. The measurements reported here provide much greater spectral coverage than the most recent measurements. The effect of O3 concentration and water vapor partial pressure were investigated, however there were no observable changes in the absorption spectrum most likely due to the low optical density of the complex.

  16. Synergic use of TOMS and Aeronet Observations for Characterization of Aerosol Absorption

    NASA Technical Reports Server (NTRS)

    Torres, O.; Bhartia, P. K.; Dubovik, O.; Holben, B.; Siniuk, A.

    2003-01-01

    The role of aerosol absorption on the radiative transfer balance of the earth-atmosphere system is one of the largest sources of uncertainty in the analysis of global climate change. Global measurements of aerosol single scattering albedo are, therefore, necessary to properly assess the radiative forcing effect of aerosols. Remote sensing of aerosol absorption is currently carried out using both ground (Aerosol Robotic Network) and space (Total Ozone Mapping Spectrometer) based observations. The satellite technique uses measurements of backscattered near ultraviolet radiation. Carbonaceous aerosols, resulting from the combustion of biomass, are one of the most predominant absorbing aerosol types in the atmosphere. In this presentation, TOMS and AERONET retrievals of single scattering albedo of carbonaceous aerosols, are compared for different environmental conditions: agriculture related biomass burning in South America and Africa and peat fires in Eastern Europe. The AERONET and TOMS derived aerosol absorption information are in good quantitative agreement. The most absorbing smoke is detected over the African Savanna. Aerosol absorption over the Brazilian rain forest is less absorbing. Absorption by aerosol particles resulting from peat fires in Eastern Europe is weaker than the absorption measured in Africa and South America. This analysis shows that the near UV satellite method of aerosol absorption characterization has the sensitivity to distinguish different levels of aerosol absorption. The analysis of the combined AERONET-TOMS observations shows a high degree of synergy between satellite and ground based observations.

  17. Infrared absorption-coefficient data on SF6 applicable to atmospheric remote sensing

    NASA Technical Reports Server (NTRS)

    Varanasi, P.; Gopalan, A.; Brannon, J. F., Jr.

    1992-01-01

    Spectral absorption coefficients, k(nu)/cm per atm, of SF6 have been measured in the central Q-branches of the nu(3)-fundamental at 947/cm at various temperature-pressure combinations representing tangent heights in solar-occultation experiments or layers in the atmosphere. The data obtained with the Doppler-limited spectral resolution (about 0.0001/cm) of a tunable-diode laser spectrometer are useful in the atmospheric remote sensing of this trace gas.

  18. Infrared absorption of methanethiol clusters (CH3SH)n, n = 2-5, recorded with a time-of-flight mass spectrometer using IR depletion and VUV ionization

    NASA Astrophysics Data System (ADS)

    Fu, Lung; Han, Hui-Ling; Lee, Yuan-Pern

    2012-12-01

    We investigated IR spectra in the CH- and SH-stretching regions of size-selected methanethiol clusters, (CH3SH)n with n = 2-5, in a pulsed supersonic jet using infrared (IR)-vacuum ultraviolet (VUV) ionization. VUV emission at 132.50 nm served as the source of ionization in a time-of-flight mass spectrometer. Clusters were dissociated with light from a tunable IR laser before ionization. The variations in intensity of methanethiol cluster ions (CH3SH)n+ were monitored as the IR laser light was tuned across the range 2470-3100 cm-1. In the SH-stretching region, the spectrum of (CH3SH)2 shows a weak band near 2601 cm-1, red-shifted only 7 cm-1 from that of the monomer. In contrast, all spectra of (CH3SH)n, n = 3-5, show a broad band near 2567 cm-1 with much greater intensity. In the CH-stretching region, absorption bands of (CH3SH)2 are located near 2865, 2890, 2944, and 3010 cm-1, red-shifted by 3-5 cm-1 from those of CH3SH. These red shifts increase slightly for larger clusters and bands near 2856, 2884, 2938, and 3005 cm-1 were observed for (CH3SH)5. These spectral results indicate that the S-H...S hydrogen bond plays an important role in clusters with n = 3-5, but not in (CH3SH)2, in agreement with theoretical predictions. The absence of a band near 2608 cm-1 that corresponds to absorption of the non-hydrogen-bonded SH moiety and the large width of observed feature near 2567 cm-1 indicate that the dominant stable structures of (CH3SH)n, n = 3-5, have a cyclic hydrogen-bonded framework.

  19. Measurements of Soot Mass Absorption Coefficients from 300 to 660 nm

    NASA Astrophysics Data System (ADS)

    Renbaum-Wolff, Lindsay; Fisher, Al; Helgestad, Taylor; Lambe, Andrew; Sedlacek, Arthur; Smith, Geoffrey; Cappa, Christopher; Davidovits, Paul; Onasch, Timothy; Freedman, Andrew

    2016-04-01

    Soot, a product of incomplete combustion, plays an important role in the earth's climate system through the absorption and scattering of solar radiation. In particular, the assumed mass absorption coefficient (MAC) of soot and its variation with wavelength presents a significant uncertainty in the calculation of radiative forcing in global climate change models. As part of the fourth Boston College/Aerodyne soot properties measurement campaign, we have measured the mass absorption coefficient of soot produced by an inverted methane diffusion flame over a spectral range of 300-660 nm using a variety of optical absorption techniques. Extinction and absorption were measured using a dual cavity ringdown photoacoustic spectrometer (CRD-PAS, UC Davis) at 405 nm and 532 nm. Scattering and extinction were measured using a CAPS PMssa single scattering albedo monitor (Aerodyne) at 630 nm; the absorption coefficient was determined by subtraction. In addition, the absorption coefficients in 8 wavelength bands from 300 to 660 nm were measured using a new broadband photoacoustic absorption monitor (UGA). Soot particle mass was quantified using a centrifugal particle mass analyzer (CPMA, Cambustion), mobility size with a scanning mobility particle sizer (SMPS, TSI) and soot concentration with a CPC (Brechtel). The contribution of doubly charged particles to the sample mass was determined using a Single Particle Soot Photometer (DMT). Over a mass range of 1-8 fg, corresponding to differential mobility diameters of ~150 nm to 550 nm, the value of the soot MAC proved to be independent of mass for all wavelengths. The wavelength dependence of the MAC was best fit to a power law with an Absorption Ångstrom Coefficient slightly greater than 1.

  20. Absorption spectroscopy setup for determination of whole human blood and blood-derived materials spectral characteristics

    NASA Astrophysics Data System (ADS)

    Wróbel, M. S.; Gnyba, M.; Milewska, D.; Mitura, K.; Karpienko, K.

    2015-09-01

    A dedicated absorption spectroscopy system was set up using tungsten-halogen broadband source, optical fibers, sample holder, and a commercial spectrometer with CCD array. Analysis of noise present in the setup was carried out. Data processing was applied to the absorption spectra to reduce spectral noise, and improve the quality of the spectra and to remove the baseline level. The absorption spectra were measured for whole blood samples, separated components: plasma, saline, washed erythrocytes in saline and human whole blood with biomarkers - biocompatible nanodiamonds (ND). Blood samples had been derived from a number of healthy donors. The results prove a correct setup arrangement, with adequate preprocessing of the data. The results of blood-ND mixtures measurements show no toxic effect on blood cells, which proves the NDs as a potential biocompatible biomarkers.

  1. Surface mineral maps of Afghanistan derived from HyMap imaging spectrometer data, version 2

    USGS Publications Warehouse

    Kokaly, Raymond F.; King, Trude V.V.; Hoefen, Todd M.

    2013-01-01

    This report presents a new version of surface mineral maps derived from HyMap imaging spectrometer data collected over Afghanistan in the fall of 2007. This report also describes the processing steps applied to the imaging spectrometer data. The 218 individual flight lines composing the Afghanistan dataset, covering more than 438,000 square kilometers, were georeferenced to a mosaic of orthorectified Landsat images. The HyMap data were converted from radiance to reflectance using a radiative transfer program in combination with ground-calibration sites and a network of cross-cutting calibration flight lines. The U.S. Geological Survey Material Identification and Characterization Algorithm (MICA) was used to generate two thematic maps of surface minerals: a map of iron-bearing minerals and other materials, which have their primary absorption features at the shorter wavelengths of the reflected solar wavelength range, and a map of carbonates, phyllosilicates, sulfates, altered minerals, and other materials, which have their primary absorption features at the longer wavelengths of the reflected solar wavelength range. In contrast to the original version, version 2 of these maps is provided at full resolution of 23-meter pixel size. The thematic maps, MICA summary images, and the material fit and depth images are distributed in digital files linked to this report, in a format readable by remote sensing software and Geographic Information Systems (GIS). The digital files can be downloaded from http://pubs.usgs.gov/ds/787/downloads/.

  2. Aerosol Absorption Measurements in MILAGRO.

    NASA Astrophysics Data System (ADS)

    Gaffney, J. S.; Marley, N. A.; Arnott, W. P.; Paredes-Miranda, L.; Barnard, J. C.

    2007-12-01

    During the month of March 2006, a number of instruments were used to determine the absorption characteristics of aerosols found in the Mexico City Megacity and nearby Valley of Mexico. These measurements were taken as part of the Department of Energy's Megacity Aerosol Experiment - Mexico City (MAX-Mex) that was carried out in collaboration with the Megacity Interactions: Local and Global Research Observations (MILAGRO) campaign. MILAGRO was a joint effort between the DOE, NSF, NASA, and Mexican agencies aimed at understanding the impacts of a megacity on the urban and regional scale. A super-site was operated at the Instituto Mexicano de Petroleo in Mexico City (designated T-0) and at the Universidad Technologica de Tecamac (designated T-1) that was located about 35 km to the north east of the T-0 site in the State of Mexico. A third site was located at a private rancho in the State of Hidalgo approximately another 35 km to the northeast (designated T-2). Aerosol absorption measurements were taken in real time using a number of instruments at the T-0 and T-1 sites. These included a seven wavelength aethalometer, a multi-angle absorption photometer (MAAP), and a photo-acoustic spectrometer. Aerosol absorption was also derived from spectral radiometers including a multi-filter rotating band spectral radiometer (MFRSR). The results clearly indicate that there is significant aerosol absorption by the aerosols in the Mexico City megacity region. The absorption can lead to single scattering albedo reduction leading to values below 0.5 under some circumstances. The absorption is also found to deviate from that expected for a "well-behaved" soot anticipated from diesel engine emissions, i.e. from a simple 1/lambda wavelength dependence for absorption. Indeed, enhanced absorption is seen in the region of 300-450 nm in many cases, particularly in the afternoon periods indicating that secondary organic aerosols are contributing to the aerosol absorption. This is likely due

  3. Rocket-borne instrumentation using the resonant absorption technique to study the geocoronal and interplanetary helium emissions.

    PubMed

    Crifo, J F; Fahr, H J; Seidi, P; Wulf-Mathies, C

    1979-09-01

    A rocket payload able to perform a thorough and independent analysis of the He I 58.43340-nm geocoronal and interplanetary emissions is presented. It includes a sun-pointed resonant absorption spectrometer and a sky-scanning resonant absorption photometer. Both incorporate a similar helium resonance cell of original design featuring a most flexible pressure scanning capability and an accurate pressure measuring device, so that scanning by wavelength bandpasses from 20 down to 1 pm can be achieved. A description of the design and calibration of the instrument is given, followed by an indication of its successful operation in flight.

  4. A systematic approach to determining the properties of an iodine absorption cell for high-precision radial velocity measurements

    NASA Astrophysics Data System (ADS)

    Perdelwitz, V.; Huke, P.

    2018-06-01

    Absorption cells filled with diatomic iodine are frequently employed as wavelength reference for high-precision stellar radial velocity determination due their long-term stability and low cost. Despite their wide-spread usage in the community, there is little documentation on how to determine the ideal operating temperature of an individual cell. We have developed a new approach to measuring the effective molecular temperature inside a gas absorption cell and searching for effects detrimental to a high precision wavelength reference, utilizing the Boltzmann distribution of relative line depths within absorption bands of single vibrational transitions. With a high resolution Fourier transform spectrometer, we took a series of 632 spectra at temperatures between 23 °C and 66 °C. These spectra provide a sufficient basis to test the algorithm and demonstrate the stability and repeatability of the temperature determination via molecular lines on a single iodine absorption cell. The achievable radial velocity precision σRV is found to be independent of the cell temperature and a detailed analysis shows a wavelength dependency, which originates in the resolving power of the spectrometer in use and the signal-to-noise ratio. Two effects were found to cause apparent absolute shifts in radial velocity, a temperature-induced shift of the order of ˜1 ms-1K-1 and a more significant effect resulting in abrupt jumps of ≥50 ms-1 is determined to be caused by the temperature crossing the dew point of the molecular iodine.

  5. VEGAS: VErsatile GBT Astronomical Spectrometer

    NASA Astrophysics Data System (ADS)

    Bussa, Srikanth; VEGAS Development Team

    2012-01-01

    The National Science Foundation Advanced Technologies and Instrumentation (NSF-ATI) program is funding a new spectrometer backend for the Green Bank Telescope (GBT). This spectrometer is being built by the CICADA collaboration - collaboration between the National Radio Astronomy Observatory (NRAO) and the Center for Astronomy Signal Processing and Electronics Research (CASPER) at the University of California Berkeley.The backend is named as VErsatile GBT Astronomical Spectrometer (VEGAS) and will replace the capabilities of the existing spectrometers. This backend supports data processing from focal plane array systems. The spectrometer will be capable of processing up to 1.25 GHz bandwidth from 8 dual polarized beams or a bandwidth up to 10 GHz from a dual polarized beam.The spectrometer will be using 8-bit analog to digital converters (ADC), which gives a better dynamic range than existing GBT spectrometers. There will be 8 tunable digital sub-bands within the 1.25 GHz bandwidth, which will enhance the capability of simultaneous observation of multiple spectral transitions. The maximum spectral dump rate to disk will be about 0.5 msec. The vastly enhanced backend capabilities will support several science projects with the GBT. The projects include mapping temperature and density structure of molecular clouds; searches for organic molecules in the interstellar medium; determination of the fundamental constants of our evolving Universe; red-shifted spectral features from galaxies across cosmic time and survey for pulsars in the extreme gravitational environment of the Galactic Center.

  6. Resolution-enhanced Mapping Spectrometer

    NASA Technical Reports Server (NTRS)

    Kumer, J. B.; Aubrun, J. N.; Rosenberg, W. J.; Roche, A. E.

    1993-01-01

    A familiar mapping spectrometer implementation utilizes two dimensional detector arrays with spectral dispersion along one direction and spatial along the other. Spectral images are formed by spatially scanning across the scene (i.e., push-broom scanning). For imaging grating and prism spectrometers, the slit is perpendicular to the spatial scan direction. For spectrometers utilizing linearly variable focal-plane-mounted filters the spatial scan direction is perpendicular to the direction of spectral variation. These spectrometers share the common limitation that the number of spectral resolution elements is given by the number of pixels along the spectral (or dispersive) direction. Resolution enhancement by first passing the light input to the spectrometer through a scanned etalon or Michelson is discussed. Thus, while a detector element is scanned through a spatial resolution element of the scene, it is also temporally sampled. The analysis for all the pixels in the dispersive direction is addressed. Several specific examples are discussed. The alternate use of a Michelson for the same enhancement purpose is also discussed. Suitable for weight constrained deep space missions, hardware systems were developed including actuators, sensor, and electronics such that low-resolution etalons with performance required for implementation would weigh less than one pound.

  7. Development of a Near-Ir Cavity Enhanced Absorption Spectrometer for the Detection of Atmospheric Oxidation Products and Organoamines

    NASA Astrophysics Data System (ADS)

    Eddingsaas, Nathan C.; Jewell, Breanna; Thurnherr, Emily

    2014-06-01

    An estimated 10,000 to 100,000 different compounds have been measured in the atmosphere, each one undergoes many oxidation reactions that may or may not degrade air quality. To date, the fate of even some of the most abundant hydrocarbons in the atmosphere is poorly understood. One difficulty is the detection of atmospheric oxidation products that are very labile and decompose during analysis. To study labile species under atmospheric conditions, a highly sensitive, non-destructive technique is needed. Here we describe a near-IR incoherent broadband cavity enhanced absorption spectroscopy (IBBCEAS) setup that we are developing to meet this end. We have chosen to utilize the near-IR, where vibrational overtone absorptions are observed, due to the clean spectral windows and better spectral separation of absorption features. In one spectral window we can simultaneously and continuously monitor the composition of alcohols, hydroperoxides, and carboxylic acids in an air mass. In addition, we have used our CEAS setup to detect organoamines. The long effective path length of CEAS allows for low detection limits, even of the overtone absorption features, at ppb and ppt levels.

  8. Ground based mid-IR heterodyne spectrometer concept for planetary atmospheres observations

    NASA Astrophysics Data System (ADS)

    Garamov, V.; Benderov, O.; Semenov, V.; Spiridonov, M.; Rodin, A.; Stepanov, B.

    2017-09-01

    We present a heterodyne spectrometer concept based on distributed feedback (DFB) quantum cascade lasers (QCL) operated in midle infrared region (MIR). The instrument is assumed to be mount on the Russian infrared observatories. The core features of the concept are compact design, utilizing a novel mid-IR fiber optical components and dynamic local oscillator frequency locking using reference molecule absorption line. The instrument characteristics are similar to modern heterodyne devices THIS (Cologne University, Germany) and MILAHI (Tohoku University, Japan) in terms of fundamental parameters, including spectral resolution, spectral coverage in a single observation. At present moment we created laboratory setup including all necessary elements of MIR heterodyne spectrometer. We have studied different components of noises of our system and found optimal value of LO power. The measured signal to noise ratio (SNR) with MCT PD was about 10 times greater than LO's shot noise (theoretical limit of heterodyne technique SNR) and limited by QCL relative intensity noise (RIN). However, applying additional filtering it is possible to reduce this value better than 5 shot noise level, which is typical to TEC cooled MCT PD. Also we demonstrate heterodyne signal measurements using laboratory black body with temperature of 400 oC.

  9. Atmospheric solar absorption measurements in the 9 to 11 mu m region using a diode laser heterodyne spectrometer

    NASA Technical Reports Server (NTRS)

    Harward, C. N.; Hoell, J. M., Jr.

    1980-01-01

    A tunable diode laser heterodyne radiometer was developed for ground-based measurements of atmospheric solar absorption spectra in the 8 to 12 microns spectral range. The performance and operating characteristics of this Tunable Infrared Heterodyne Radiometer (TIHR) are discussed along with atmospheric solar absorption spectra of HNO3, O3, CO2, and H2O in the 9 to 11 microns spectral region.

  10. Electron/proton spectrometer certification documentation analyses

    NASA Technical Reports Server (NTRS)

    Gleeson, P.

    1972-01-01

    A compilation of analyses generated during the development of the electron-proton spectrometer for the Skylab program is presented. The data documents the analyses required by the electron-proton spectrometer verification plan. The verification plan was generated to satisfy the ancillary hardware requirements of the Apollo Applications program. The certification of the spectrometer requires that various tests, inspections, and analyses be documented, approved, and accepted by reliability and quality control personnel of the spectrometer development program.

  11. Measuring Transmission Efficiencies Of Mass Spectrometers

    NASA Technical Reports Server (NTRS)

    Srivastava, Santosh K.

    1989-01-01

    Coincidence counts yield absolute efficiencies. System measures mass-dependent transmission efficiencies of mass spectrometers, using coincidence-counting techniques reminiscent of those used for many years in calibration of detectors for subatomic particles. Coincidences between detected ions and electrons producing them counted during operation of mass spectrometer. Under certain assumptions regarding inelastic scattering of electrons, electron/ion-coincidence count is direct measure of transmission efficiency of spectrometer. When fully developed, system compact, portable, and used routinely to calibrate mass spectrometers.

  12. Experimental observation of the shift and width of the aluminium K absorption edge in laser shock-compressed plasmas

    NASA Astrophysics Data System (ADS)

    Hall, T. A.; Al-Kuzee, J.; Benuzzi, A.; Koenig, M.; Krishnan, J.; Grandjouan, N.; Batani, D.; Bossi, S.; Nicolella, S.

    1998-03-01

    Experimental measurements of the shift and width of the aluminium K-absorption edge in laser shock-compressed plasma is presented. The spectrometer used in these experiments allows an accurate wavelength calibration and fiduciary and hence provides precise measurements of both the shift and the width of the absorption edge. Results have been obtained for compressions up to approximately ×2 and temperatures up to about 1.5 eV. The values of shift and width are compared with a new model with which there is very good agreement.

  13. 15 pixels digital autocorrelation spectrometer system

    NASA Astrophysics Data System (ADS)

    Lee, Changhoon; Kim, Hyo-Ryung; Kim, Kwang-Dong; Chung, Mun-Hee; Timoc, C.

    2006-06-01

    In this paper describes the system configuration and the some performance test results of the 15 pixels digital autocorrelation spectrometer to be used at the Taeduk Radio Astronomy Observatory (TRAO) of Korea. This autocorrelation spectrometer instrument enclosed in a 3-slot VXI module and controlled via a USB port by a backend PC. This spectrometer system consists of the 4 band-pass filters unit, the digitizer, the 512 lags correlator, the clock distribution unit, and USB controller. And here we describe the frequency accuracy and the root-mean-square noise characteristic of this spectrometer. After some calibration procedure, this spectrometer can be use as the back-end system at TRAO for the 3x5 focal plane array receivers.

  14. The multi-mode polarization modulation spectrometer: part 1: simultaneous detection of absorption, turbidity, and optical activity.

    PubMed

    Arvinte, Tudor; Bui, Tam T T; Dahab, Ali A; Demeule, Barthélemy; Drake, Alex F; Elhag, Dhia; King, Peter

    2004-09-01

    Circular dichroism (CD) is an important spectroscopic technique for monitoring chirality and biological macromolecule conformation. However, during a CD measurement, absorbance, light scattering/turbidity, and fluorescence can also be detected. The simultaneous measurement of these different spectral features for a single sample is the basis of a multi-mode optical spectrometer. This allows time-efficient gathering of complementary information and provides a scheme to ensure that CD measurements are reliable. Aspects of circular polarization differential light scattering, pH, and temperature variation of a protein (antibody) solution are described. A procedure to help ensure that CD measurements are reliable is described.

  15. Mid-IR spectrometer for mobile, real-time urban NO2 measurements

    NASA Astrophysics Data System (ADS)

    Morten Hundt, P.; Müller, Michael; Mangold, Markus; Tuzson, Béla; Scheidegger, Philipp; Looser, Herbert; Hüglin, Christoph; Emmenegger, Lukas

    2018-05-01

    Detailed knowledge about the urban NO2 concentration field is a key element for obtaining accurate pollution maps and individual exposure estimates. These are required for improving the understanding of the impact of ambient NO2 on human health and for related air quality measures. However, city-scale NO2 concentration maps with high spatio-temporal resolution are still lacking, mainly due to the difficulty of accurate measurement of NO2 at the required sub-ppb level precision. We contribute to close this gap through the development of a compact instrument based on mid-infrared laser absorption spectroscopy. Leveraging recent advances in infrared laser and detection technology and a novel circular absorption cell, we demonstrate the feasibility and robustness of this technique for demanding mobile applications. A fully autonomous quantum cascade laser absorption spectrometer (QCLAS) has been successfully deployed on a tram, performing long-term and real-time concentration measurements of NO2 in the city of Zurich (Switzerland). For ambient NO2 concentrations, the instrument demonstrated a precision of 0.23 ppb at one second time resolution and of 0.03 ppb after 200 s averaging. Whilst the combined uncertainty estimated for the retrieved spectroscopic values was less than 5 %, laboratory intercomparison measurements with standard CLD instruments revealed a systematic NO2 wall loss of about 10 % within the laser spectrometer. For the field campaign, the QCLAS has been referenced to a CLD using urban atmospheric air, despite the potential cross sensitivity of CLD to other nitrogen containing compounds. However, this approach allowed a direct comparison and continuous validation of the spectroscopic data to measurements at regulatory air quality monitoring (AQM) stations along the tram-line. The analysis of the recorded high-resolution time series allowed us to gain more detailed insights into the spatio-temporal concentration distribution of NO2 in an urban

  16. Performance of three reflectance calibration methods for airborne hyperspectral spectrometer data.

    PubMed

    Miura, Tomoaki; Huete, Alfredo R

    2009-01-01

    In this study, the performances and accuracies of three methods for converting airborne hyperspectral spectrometer data to reflectance factors were characterized and compared. The "reflectance mode (RM)" method, which calibrates a spectrometer against a white reference panel prior to mounting on an aircraft, resulted in spectral reflectance retrievals that were biased and distorted. The magnitudes of these bias errors and distortions varied significantly, depending on time of day and length of the flight campaign. The "linear-interpolation (LI)" method, which converts airborne spectrometer data by taking a ratio of linearly-interpolated reference values from the preflight and post-flight reference panel readings, resulted in precise, but inaccurate reflectance retrievals. These reflectance spectra were not distorted, but were subject to bias errors of varying magnitudes dependent on the flight duration length. The "continuous panel (CP)" method uses a multi-band radiometer to obtain continuous measurements over a reference panel throughout the flight campaign, in order to adjust the magnitudes of the linear-interpolated reference values from the preflight and post-flight reference panel readings. Airborne hyperspectral reflectance retrievals obtained using this method were found to be the most accurate and reliable reflectance calibration method. The performances of the CP method in retrieving accurate reflectance factors were consistent throughout time of day and for various flight durations. Based on the dataset analyzed in this study, the uncertainty of the CP method has been estimated to be 0.0025 ± 0.0005 reflectance units for the wavelength regions not affected by atmospheric absorptions. The RM method can produce reasonable results only for a very short-term flight (e.g., < 15 minutes) conducted around a local solar noon. The flight duration should be kept shorter than 30 minutes for the LI method to produce results with reasonable accuracies. An important

  17. SU-F-J-46: Feasibility of Cerenkov Emission for Absorption Spectroscopy

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

    Oraiqat, I; Rehemtulla, A; Lam, K

    2016-06-15

    Purpose: Cerenkov emission (CE) is a promising tool for online tumor microenvironment interrogation and targeting during radiotherapy. In this work, we utilize CE generated during radiotherapy as a broadband excitation source for real-time absorption spectroscopy. We demonstrate the feasibility of CE spectroscopy using a controlled experiment of materials with known emission/absorption properties. Methods: A water tank is irradiated with 20 MeV electron beam to induce Cerenkov emission. Food coloring dyes (Yellow #5, Red #40, and Blue #1), which have known emission/absorption properties were added to the water tank with increasing concentration (1 drop (0.05 mL), 2 drops, and 4 dropsmore » from a dispenser bottle). The signal is collected using a condensing lens which is coupled into a 20m optical fiber that is fed into a spectrometer that measures the emitted spectra. The resulting spectra from water/food coloring dye solutions were normalized by the reference spectrum, which is the Cerenkov spectrum of pure water, correcting for both the nonlinearity of the broadband Cerenkov emission spectrum as well as the non-uniform spectral response of the spectrometer. The emitted spectra were then converted into absorbance and their characteristics were analyzed. Results: The food coloring dye had a drastic change on the Cerenkov emission, shifting its wavelength according to its visible color. The collected spectra showed various absorbance peaks which agrees with tabulated peak positions of the dyes added within 0.3% for yellow, 1.7% for red, and 0.16% for blue. The CE peak heights proportionally increased as the dye concentration is increased. Conclusion: This work shows the potential for real-time functional spectroscopy using Cerenkov emission during radiotherapy. It was demonstrated that molecule identification as well as relative concentration can be extracted from the Cerenkov emission color shift.« less

  18. Imaging spectrometer/camera having convex grating

    NASA Technical Reports Server (NTRS)

    Reininger, Francis M. (Inventor)

    2000-01-01

    An imaging spectrometer has fore-optics coupled to a spectral resolving system with an entrance slit extending in a first direction at an imaging location of the fore-optics for receiving the image, a convex diffraction grating for separating the image into a plurality of spectra of predetermined wavelength ranges; a spectrometer array for detecting the spectra; and at least one concave sperical mirror concentric with the diffraction grating for relaying the image from the entrance slit to the diffraction grating and from the diffraction grating to the spectrometer array. In one embodiment, the spectrometer is configured in a lateral mode in which the entrance slit and the spectrometer array are displaced laterally on opposite sides of the diffraction grating in a second direction substantially perpendicular to the first direction. In another embodiment, the spectrometer is combined with a polychromatic imaging camera array disposed adjacent said entrance slit for recording said image.

  19. Quartz-based flat-crystal resonant inelastic x-ray scattering spectrometer with sub-10 meV energy resolution

    DOE PAGES

    Kim, Jungho; Casa, D.; Said, Ayman; ...

    2018-01-31

    Continued improvement of the energy resolution of resonant inelastic x-ray scattering (RIXS) spectrometers is crucial for fulfilling the potential of this technique in the study of electron dynamics in materials of fundamental and technological importance. In particular, RIXS is the only alternative tool to inelastic neutron scattering capable of providing fully momentum resolved information on dynamic spin structures of magnetic materials, but is limited to systems whose magnetic excitation energy scales are comparable to the energy resolution. The state-of-the-art spherical diced crystal analyzer optics provides energy resolution as good as 25 meV but has already reached its theoretical limit. Formore » this study, we demonstrate a novel sub-10 meV RIXS spectrometer based on flat-crystal optics at the Ir-L3 absorption edge (11.215 keV) that achieves an analyzer energy resolution of 3.9 meV, very close to the theoretical value of 3.7 meV. In addition, the new spectrometer allows efficient polarization analysis without loss of energy resolution. The performance of the instrument is emonstrated using longitudinal acoustical and optical phonons in diamond, and magnon in Sr 3Ir 2O 7. The novel sub-10 meV RIXS spectrometer thus provides a window into magnetic materials with small energy scales.« less

  20. Quartz-based flat-crystal resonant inelastic x-ray scattering spectrometer with sub-10 meV energy resolution

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

    Kim, Jungho; Casa, D.; Said, Ayman

    Continued improvement of the energy resolution of resonant inelastic x-ray scattering (RIXS) spectrometers is crucial for fulfilling the potential of this technique in the study of electron dynamics in materials of fundamental and technological importance. In particular, RIXS is the only alternative tool to inelastic neutron scattering capable of providing fully momentum resolved information on dynamic spin structures of magnetic materials, but is limited to systems whose magnetic excitation energy scales are comparable to the energy resolution. The state-of-the-art spherical diced crystal analyzer optics provides energy resolution as good as 25 meV but has already reached its theoretical limit. Formore » this study, we demonstrate a novel sub-10 meV RIXS spectrometer based on flat-crystal optics at the Ir-L3 absorption edge (11.215 keV) that achieves an analyzer energy resolution of 3.9 meV, very close to the theoretical value of 3.7 meV. In addition, the new spectrometer allows efficient polarization analysis without loss of energy resolution. The performance of the instrument is emonstrated using longitudinal acoustical and optical phonons in diamond, and magnon in Sr 3Ir 2O 7. The novel sub-10 meV RIXS spectrometer thus provides a window into magnetic materials with small energy scales.« less

  1. A cryogenically cooled, multidetector spectrometer for infrared astronomy

    NASA Technical Reports Server (NTRS)

    Witteborn, F. C.; Bregman, J. D.

    1984-01-01

    A liquid helium-cooled, 24 detector grating spectrometer was developed and used for low resolution astronomical observations in the 5 to 14 micron spectral range. The instrument operated on the 91 cm Kuiper Airborne Observatory, the 3 m IRTF (Mauna Kea), the 3 m Shane telescope Observatory, the 3 m Shane telescope (Lick Observatory), and the 152 cm NASA and University of Arizona telescope. The detectors are discrete Si:Bi photoconductors with individual metal oxide semiconductor field effect transistor preamplifiers operating at 4 K. The system uses a liquid helium-cooled slit, order-sorter filter, collimator mirror, grating, and camera mirror arranged in a Czerny-Turner configuration with a cold stop added between the collimator mirror and the grating. The distances between components are chosen so that the collimator mirror images the secondary mirror of the telescope onto the cold stop, thus providing a very effective baffle. Scattered radiation is effectively reduced by using liquid helium-cooled, black baffles to divide the spectrometer into three separate compartments. The system noise-equivalent flux density, when used on the 152 cm telescope from 8 to 13 microns with a resolving power of 50, is 4.4 x 10 to the minus 17th power W/sq cm micron square root of Hz. The main applications are for measuring continuum radiation levels and solid state emission and absorption features in regions of star and planet formation.

  2. Complete ? -decay pattern for the high-priority decay-heat isotopes I 137 and Xe 137 determined using total absorption spectroscopy

    DOE PAGES

    Rasco, B. C.; Rykaczewski, K. P.; Fijalkowska, A.; ...

    2017-05-31

    We measured the complete -decay intensities of 137I and 137Xe with the Modular Total Absorption Spectrometer at Oak Ridge National Laboratory. We describe a novel technique for measuring the -delayed neutron energy spectrum, which also provides a measurement of the -neutron branching ratio, P n.

  3. Io: Near-Infrared Absorptions Not Attributable to SO2

    NASA Astrophysics Data System (ADS)

    Shirley, J. H.; Clark, R. N.; Soderblom, L. A.; Carlson, R. W.; Kamp, L. W.; Galileo NIMS Team

    2001-11-01

    The Near-Infrared Mapping Spectrometer (NIMS) onboard the Galileo spacecraft imaged the leading side of Jupiter's satellite Io at full spectral resolution and with triple Nyquist spatial sampling during the fifteenth orbital encounter (E15). New despiking and "dejittering" algorithms have been applied to this high S/N observation (15INHRSPEC01A). Spectral absorption features not attributable to SO2 are found between 3.0-3.4 microns and near 4.65 microns. The patterns of the spatial distributions of both absorbers differ from that of the omnipresent SO2. The broad 3.0-3.4 micron absorption is most pronounced in polar regions. Preliminary work suggests that the 4.65 micron feature may be associated with an unidentified sulfate mineral, while the 3.0-3.4 micron feature may result from the presence of more than one absorbing material. Hydrogen-bearing species are likely candidates. For example, H2O ice provides a good match for the absorption near 3.2 microns, but the absorption is shifted to wavelengths longer than that in pure H2O ice. If only one absorber is present, then hydrogen bonding of small numbers of H2O molecules could perhaps account for the shift. The absorption is weak; if H20 related, optical path lengths of a fraction of a micron are indicated. Portions of this research were carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

  4. Year-round measurements of ozone at 66 deg S with a visible spectrometer

    NASA Technical Reports Server (NTRS)

    Roscoe, Howard K.; Oldham, Derek J.; Squires, James A. C.; Pommereau, Jean-Pierre; Goutail, Florence; Sarkissian, Alain

    1994-01-01

    In March 1990, a zenith-sky UV-visible spectrometer of the design 'Systeme Automatique d'Obervation Zenithal' (SAOZ) was installed at Faraday in Antarctica (66.3 deg S, 64.3 deg W). SAOZ records spectra between 290 and 600 nm during daylight. Its analysis program fits laboratory spectra of constituents, at various wavelengths, to the differential of the ratio of the observed spectrum and a reference spectrum. The least-squares fitting procedure minimizes the sum-of-squares of residuals. Ozone is deduced from absorption in its visible bands between 500 and 560 nm. The fortunate colocation of this SAOZ with the well-calibrated Dobson at Faraday has allowed us to examine the calibration of the zero of the SAOZ, difficult at visible wavelengths because of the small depth of absorption. Here we describe recent improvements and limitations to this calibration, and discuss SAOZ measurements of ozone during winter in this important location at the edge of the Antarctic vortex.

  5. Low-temperature THz time domain waveguide spectrometer with butt-coupled emitter and detector crystal.

    PubMed

    Qiao, W; Stephan, D; Hasselbeck, M; Liang, Q; Dekorsy, T

    2012-08-27

    A compact high-resolution THz time-domain waveguide spectrometer that is operated inside a cryostat is demonstrated. A THz photo-Dember emitter and a ZnTe electro-optic detection crystal are directly attached to a parallel copper-plate waveguide. This allows the THz beam to be excited and detected entirely inside the cryostat, obviating the need for THz-transparent windows or external THz mirrors. Since no external bias for the emitter is required, no electric feed-through into the cryostat is necessary. Using asynchronous optical sampling, high resolution THz spectra are obtained in the frequency range from 0.2 to 2.0 THz. The THz emission from the photo-Dember emitter and the absorption spectrum of 1,2-dicyanobenzene film are measured as a function of temperature. An absorption peak around 750 GHz of 1,2-dicyanobenzene displays a blue shift with increasing temperature.

  6. The OSIRIS-REx Visible and InfraRed Spectrometer (OVIRS): Spectral Maps of the Asteroid Bennu

    NASA Astrophysics Data System (ADS)

    Reuter, D. C.; Simon, A. A.; Hair, J.; Lunsford, A.; Manthripragada, S.; Bly, V.; Bos, B.; Brambora, C.; Caldwell, E.; Casto, G.; Dolch, Z.; Finneran, P.; Jennings, D.; Jhabvala, M.; Matson, E.; McLelland, M.; Roher, W.; Sullivan, T.; Weigle, E.; Wen, Y.; Wilson, D.; Lauretta, D. S.

    2018-03-01

    The OSIRIS-REx Visible and Infrared Spectrometer (OVIRS) is a point spectrometer covering the spectral range of 0.4 to 4.3 microns (25,000-2300 cm-1). Its primary purpose is to map the surface composition of the asteroid Bennu, the target asteroid of the OSIRIS-REx asteroid sample return mission. The information it returns will help guide the selection of the sample site. It will also provide global context for the sample and high spatial resolution spectra that can be related to spatially unresolved terrestrial observations of asteroids. It is a compact, low-mass (17.8 kg), power efficient (8.8 W average), and robust instrument with the sensitivity needed to detect a 5% spectral absorption feature on a very dark surface (3% reflectance) in the inner solar system (0.89-1.35 AU). It, in combination with the other instruments on the OSIRIS-REx Mission, will provide an unprecedented view of an asteroid's surface.

  7. Diagnosis of a two wire X-pinch by X-ray absorption spectroscopy utilizing a doubly curved ellipsoidal crystal

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

    Cahill, A. D., E-mail: adc87@cornell.edu; Hoyt, C. L., E-mail: adc87@cornell.edu; Shelkovenko, T. A., E-mail: adc87@cornell.edu

    2014-12-15

    X-ray absorption spectroscopy is a powerful tool for the diagnosis of plasmas over a wide range of both temperature and density. However, such a measurement is often limited to probing plasmas with temperatures well below that of the x-ray source in order to avoid object plasma emission lines from obscuring important features of the absorption spectrum. This has excluded many plasmas from being investigated by this technique. We have developed an x-ray spectrometer that provides the ability to record absorption spectra from higher temperature plasmas than the usual approach allows without the risk of data contamination by line radiation emittedmore » by the plasma under study. This is accomplished using a doubly curved mica crystal which is bent both elliptically and cylindrically. We present here initial absorption spectra obtained from an aluminum x-pinch plasma.« less

  8. Accuracy Assessments and Validation of an Expanded UV Irradiance Database from Satellite Total Ozone Mapping Spectrometer (TOMS)

    NASA Technical Reports Server (NTRS)

    Krotkov, N. A.; Herman, J.; Fioletov, V.; Seftor, C.; Larko, D.; Vasilkov, A.

    2004-01-01

    The TOMS UV irradiance database (1978 to 2000) has been expanded to include 5 new products (noon irradiance at 305, 310, 324, and 380 nm, and noon erythemal-weighted irradiance), in addition to the existing erythemal daily exposure, which permit direct Comparisons with ground-based measurements from UV spectrometers. Sensitivity studies are conducted to estimate uncertainties of the new TOMS UV irradiance data due to algorithm apriori assumptions. Comparisons with Brewer spectrometers as well as filter radiometers are used to review of the sources of known errors. Inability to distinguish between snow and cloud cover using only TOMS data results in large errors in estimating surface UV using snow climatology. A correction is suggested for the case when the regional snow albedo is known from an independent source. The summer-time positive bias between TOMS UV estimations and Brewer measurements can be seen at all wavelengths. This suggests the difference is not related to ozone absorption effects. We emphasize that uncertainty of boundary layer UV aerosol absorption properties remains a major source of error in modeling UV irradiance in clear sky conditions. Neglecting aerosol absorption by the present TOMS algorithm results in a positive summertime bias in clear-sky UV estimations over many locations. Due to high aerosol variability the bias is strongly site dependent. Data from UV-shadow-band radiometer and well-calibrated CIMEL sun-sky radiometer are used to quantify the bias at NASA/GSFC site in Greenbelt, MD. Recommendations are given to enable potential users to better account for local conditions by combining standard TOMS UV data with ancillary ground measurements.

  9. Determination of tetraalkyllead compounds in gasoline by liquid chromatography-atomic absorption spectrometry

    USGS Publications Warehouse

    Messman, J.D.; Rains, T.C.

    1981-01-01

    A liquid chromatography-atomic absorption spectrometry (LC-AAS) hybrid analytical technique is presented for metal speciation measurements on complex liquid samples. The versatility and inherent metal selectivity of the technique are Illustrated by the rapid determination of five tetraalkyllead compounds in commercial gasoline. Separation of the individual tetraalkyllead species is achieved by reversed-phase liquid chromatography using an acetonitrile/water mobile phase. The effluent from the liquid Chromatograph Is introduced directly into the aspiration uptake capillary of the nebulizer of an air/acetylene flame atomic absorption spectrometer. Spectral interferences due to coeluting hydrocarbon matrix constituents were not observed at the 283.3-nm resonance line of lead used for analysis. Detection limits of this LC-AAS hydrid analytical technique, based on a 20-??L injection, are approximately 10 ng Pb for each tetraalkyllead compound.

  10. Single-ended retroreflection sensors for absorption spectroscopy in high-temperature environments

    NASA Astrophysics Data System (ADS)

    Melin, Scott T.; Wang, Ze; Neal, Nicholas J.; Rothamer, David A.; Sanders, Scott T.

    2017-04-01

    Novel single-ended sensor arrangements are demonstrated for in situ absorption spectroscopy in combustion and related test articles. A single-ended optical access technique based on back-reflection from a polished test article surface is presented. H2O vapor absorption spectra were measured at 10 kHz in a homogeneous-charge compression-ignition engine using a sensor of this design collecting back-reflection from a polished piston surface. The measured spectra show promise for high-repetition-rate measurements in practical combustion devices. A second sensor was demonstrated based on a modification to this optical access technique. The sensor incorporates a nickel retroreflective surface as back-reflector to reduce sensitivity to beam steering and misalignment. In a propane-fired furnace, H2O vapor absorption spectra were obtained over the range 7315-7550 cm- 1 at atmospheric pressure and temperatures up to 775 K at 20 Hz using an external-cavity diode laser spectrometer. Gas properties of temperature and mole fraction were obtained from this furnace data using a band-shape spectral fitting technique. The temperature accuracy of the band-shape fitting was demonstrated to be ±1.3 K for furnace measurements at atmospheric pressure. These results should extend the range of applications in which absorption spectroscopy sensors are attractive candidates.

  11. Absolute ozone absorption cross section in the Huggins Chappuis minimum (350-470 nm) at 296 K

    NASA Astrophysics Data System (ADS)

    Axson, J. L.; Washenfelder, R. A.; Kahan, T. F.; Young, C. J.; Vaida, V.; Brown, S. S.

    2011-08-01

    We report the ozone absolute absorption cross section between 350-470 nm, the minimum between the Huggins and Chappuis bands, where the ozone cross section is less than 10-22 cm2. Ozone spectra were acquired using an incoherent broadband cavity enhanced absorption spectrometer, with three channels centered at 365, 405, and 455 nm. The accuracy of the measured cross section is 2 %. Previous measurements vary by more than an order of magnitude in this spectral region. The measurements reported here provide much greater spectral coverage than the most recent measurements. We report a minimum absorption cross section of 3.4×10-24 cm2 at 381.8 nm, which is 22 % lower than the previously reported value. The effect of O3 concentration and water vapor partial pressure were investigated, however there were no observable changes in the absorption spectrum most likely due to the low optical density of the complex.

  12. Light Absorption of Brown Carbon Aerosol in the Pearl River Delta Region of China

    NASA Astrophysics Data System (ADS)

    Huang, X.

    2015-12-01

    X.F. Huang, J.F. Yuan, L.M. Cao, J. Cui, C.N. Huang, Z.J. Lan and L.Y. He Key Laboratory for Urban Habitat Environmental Science and Technology, School of Environment and Energy, Peking University Shenzhen Graduate School, Shenzhen 518055, ChinaCorresponding author. Tel.: +86 755 26032532; fax: +86 755 26035332. E-mail address: huangxf@pku.edu.cn (X. F. Huang). Abstract: The strong spectral dependence of light absorption of brown carbon (BrC) aerosol has been recognized in recent decades. The Absorption Angstrom Exponent (AAE) of ambient aerosol was widely used in previous studies to attribute light absorption of brown carbon at shorter wavelengths, with a theoretical assumption that the AAE of black carbon (BC) aerosol equals to unit. In this study, the AAE method was improved by statistical extrapolation based on ambient measurements in the polluted seasons in typical urban and rural areas in the Pearl River Delta (PRD) region of China. A three-wavelength photoacoustic soot spectrometer (PASS-3) and an aerosol mass spectrometer (AMS) were used to explore the relationship between the ambient measured AAE and the ratio of organic aerosol to BC aerosol, in order to extract the more realistic AAE by pure BC aerosol, which were found to be 0.86, 0.82 and 1.02 at 405nm and 0.70, 0.71, and 0.86 at 532nm in the campaigns of urban-winter, urban-fall, and rural-fall, respectively. Roadway tunnel experiment results further supported the effectiveness of the obtained AAE for pure BC aerosol. In addition, biomass burning experiments proved higher spectral dependence of more-BrC environment and further verified the reliability of the instruments' response. Then, the average light absorption contribution of BrC aerosol was calculated to be 11.7, 6.3 and 12.1% (with total relative uncertainty of 7.5, 6.9 and 10.0%) at 405nm and 10.0, 4.1 and 5.5% (with total relative uncertainty of 6.5, 8.6 and 15.4%) at 532nm of the three campaigns, respectively. These results indicate that the

  13. [Optimum design of imaging spectrometer based on toroidal uniform-line-spaced (TULS) spectrometer].

    PubMed

    Xue, Qing-Sheng; Wang, Shu-Rong

    2013-05-01

    Based on the geometrical aberration theory, a optimum-design method for designing an imaging spectrometer based on toroidal uniform grating spectrometer is proposed. To obtain the best optical parameters, twice optimization is carried out using genetic algorithm(GA) and optical design software ZEMAX A far-ultraviolet(FUV) imaging spectrometer is designed using this method. The working waveband is 110-180 nm, the slit size is 50 microm x 5 mm, and the numerical aperture is 0.1. Using ZEMAX software, the design result is analyzed and evaluated. The results indicate that the MTF for different wavelengths is higher than 0.7 at Nyquist frequency 10 lp x mm(-1), and the RMS spot radius is less than 14 microm. The good imaging quality is achieved over the whole working waveband, the design requirements of spatial resolution 0.5 mrad and spectral resolution 0.6 nm are satisfied. It is certificated that the optimum-design method proposed in this paper is feasible. This method can be applied in other waveband, and is an instruction method for designing grating-dispersion imaging spectrometers.

  14. On-line ion-exchange preconcentration and determination of traces of platinum by electrothermal atomic absorption spectrometry.

    PubMed

    González García, M M; Sánchez Rojas, F; Bosch Ojeda, C; García de Torres, A; Cano Pavón, J M

    2003-04-01

    A method to determine trace amounts of platinum in different samples based on electrothermal atomic absorption spectrometry is described. The preconcentration step is performed on a chelating resin microcolumn [1,5-bis(2-pyridyl)-3-sulfophenyl methylene thiocarbonohydrazide (PSTH) immobilized on an anion-exchange resin (Dowex 1x8-200)] placed in the autosampler arm. The combination of a peristaltic pump for sample loading and the atomic absorption spectrometer pumps for elution through a selection valve simplifies the hardware. The peristaltic pump and the selection valve are easily controlled electronically with two switches placed in the autosampler, which are activated when the autosampler arm is down. Thus, the process is fully automated without any modification of the software of the atomic absorption spectrometer. Under the optimum conditions with a 60-s preconcentration time, a sample flow rate of 2.4 mL min(-1), and an injection volume of eluent of 40 microL, a linear calibration graph was obtained in the range 0-100 ng mL(-1). The enrichment factor was 14. The detection limit under these conditions is 1 ng mL(-1), and the relative standard deviation (RSD) is 1.6% for 10 ng mL(-1) of Pt. The method has been applied to the determination of platinum in catalyst, vegetation, soil, and natural water samples. The results showed good agreement with the certified value and the recoveries of Pt added to samples were 98-105%.

  15. Spectrometers for compact neutron sources

    NASA Astrophysics Data System (ADS)

    Voigt, J.; Böhm, S.; Dabruck, J. P.; Rücker, U.; Gutberlet, T.; Brückel, T.

    2018-03-01

    We discuss the potential for neutron spectrometers at novel accelerator driven compact neutron sources. Such a High Brilliance Source (HBS) relies on low energy nuclear reactions, which enable cryogenic moderators in very close proximity to the target and neutron optics at comparably short distances from the moderator compared to existing sources. While the first effect aims at increasing the phase space density of a moderator, the second allows the extraction of a large phase space volume, which is typically requested for spectrometer applications. We find that competitive spectrometers can be realized if (a) the neutron production rate can be synchronized with the experiment repetition rate and (b) the emission characteristics of the moderator can be matched to the phase space requirements of the experiment. MCNP simulations for protons or deuterons on a Beryllium target with a suitable target/moderator design yield a source brightness, from which we calculate the sample fluxes by phase space considerations for different types of spectrometers. These match closely the figures of todays spectrometers at medium flux sources. Hence we conclude that compact neutron sources might be a viable option for next generation neutron sources.

  16. Biomass Burning Dominates Brown Carbon Absorption in the Rural Southeastern U.S.

    NASA Astrophysics Data System (ADS)

    Washenfelder, R. A.; Attwood, A. R.; Brock, C. A.; Brown, S. S.; Guo, H.; Weber, R. J. J.; Xu, L.; Ng, N. L.; Stone, E. A.; Edgerton, E. S.; Baumann, K.; Hu, W.; Palm, B. B.; Jimenez, J. L.; Fry, J.; Ayres, B. R.; Draper, D.; Allen, H.

    2014-12-01

    Aerosol scattering and absorption are still among the largest uncertainties in quantifying radiative forcing. Brown carbon has a wavelength-dependent absorption that increases in the UV spectral region, and its major atmospheric sources include biomass burning, anthropogenic combustion of fossil fuels, and secondary organic aerosol. The rural Southeastern U.S. is influenced by high isoprene concentrations and varying concentrations of biomass burning aerosol, making it an ideal place to compare the relative contributions of these two sources to the brown carbon absorption budget. During the Southern Oxidant and Aerosol Study in summer 2013, we deployed a new field instrument that uses cavity enhanced spectroscopy with a broadband light source to measure aerosol optical extinction as a function of wavelength. The instrument consists of two broadband channels which span the 360-390 and 385-420 nm spectral regions using two light emitting diodes (LED) and a grating spectrometer with charge-coupled device (CCD) detector. We combine these data with direct absorption measurements of water-soluble organic carbon obtained from a novel UV/VIS-WSOC instrument, and with aerosol composition measurements. We examine these data sets to determine: 1) the optical closure between measured dry aerosol extinction and values calculated from aerosol composition and size distribution; 2) the magnitude of brown and black carbon absorption; 3) the relative contributions of biomass burning, anthropogenic, and secondary organic aerosol contributions to brown carbon absorption in the Southeast U.S. during the summer. We conclude that biomass burning is a major contributor to optical absorption by organic aerosol in the rural southeastern U.S.

  17. Temperature-dependent mid-IR absorption spectra of gaseous hydrocarbons

    NASA Astrophysics Data System (ADS)

    Klingbeil, Adam E.; Jeffries, Jay B.; Hanson, Ronald K.

    2007-10-01

    Quantitative mid-IR absorption spectra (2500 3400 cm-1) for 12 pure hydrocarbon compounds are measured at temperatures ranging from 25 to 500 °C using an FTIR spectrometer. The hydrocarbons studied are n-pentane, n-heptane, n-dodecane, 2,2,4-trimethyl-pentane (iso-octane), 2-methyl-butane, 2-methyl-pentane, 2,4,4-trimethyl-1-pentene, 2-methyl-2-butene, propene, toluene, m-xylene, and ethylbenzene. Room-temperature measurements of neat hydrocarbon vapor were made with an instrument resolution of both 0.1 and 1 cm-1 (FWHM) to confirm that the high-resolution setting was required only to resolve the propene absorption spectrum while the spectra of the other hydrocarbons could be resolved with 1 cm-1 resolution. High-resolution (0.1 cm-1), room-temperature measurements of neat hydrocarbons were made at low pressure (˜1 Torr, 133 Pa) and compared to measurements of hydrocarbon/N2 mixtures at atmospheric pressure to verify that no pressure broadening could be observed over this pressure range. The temperature was varied between 25 and 500 °C for atmospheric-pressure measurements of hydrocarbon/N2 mixtures (Xhydrocarbon˜0.06 1.5%) and it was found that the absorption cross section shows simple temperature-dependent behavior for a fixed wavelength over this temperature range. Comparisons with previous FTIR data over a limited temperature range and with high-resolution laser absorption data over a wide temperature range show good agreement.

  18. Far-infrared heterodyne spectrometer

    NASA Technical Reports Server (NTRS)

    Boreiko, Rita T.; Betz, Al L.

    1995-01-01

    A far-infrared heterodyne spectrometer was designed and built by our group for observations of atomic and molecular lines from interstellar clouds. Linewidths as narrow as 1 km/s can be expected from such regions, and so the spectrometer is designed with sub-km/s resolution so that observed line profiles will be resolved. Since its debut on the Kuiper Airborne Observatory (KAO) in 1985, the instrument has been used in regular annual flight programs from both Moffett Field, CA and Christchurch, NZ. The basic plan of the spectrometer remains unchanged from the original design presented at the previous airborne science symposium. Numerous improvements and updates to the technical capability have of course been included over the many years of operational service.

  19. Precision saturated absorption spectroscopy of H3+

    NASA Astrophysics Data System (ADS)

    Guan, Yu-Chan; Chang, Yung-Hsiang; Liao, Yi-Chieh; Peng, Jin-Long; Wang, Li-Bang; Shy, Jow-Tsong

    2018-03-01

    In our previous work on the Lamb-dips of the ν2 fundamental band transitions of H3+, the saturated absorption spectrum was obtained by third-derivative spectroscopy using frequency modulation with an optical parametric oscillator (OPO). However, frequency modulation also caused errors in the absolute frequency determination. To solve this problem, we built a tunable offset locking system to lock the pump frequency of the OPO to an iodine-stabilized Nd:YAG laser. With this improvement, we were able to scan the OPO idler frequency precisely and obtain the saturated absorption profile using intensity modulation. Furthermore, ion concentration modulation was employed to subtract the background noise and increase the signal-to-noise ratio. To determine the absolute frequency of the idler wave, the OPO signal frequency was locked to an optical frequency comb. The absolute frequency accuracy of our spectrometer was better than 7 kHz, demonstrated by measuring the wavelength standard transition of methane at 3.39 μm. Finally, we measured 16 transitions of H3+ and our results agree very well with other precision measurements. This work successfully resolved the discrepancies between our previous measurements and other precision measurements.

  20. Method for calibrating mass spectrometers

    DOEpatents

    Anderson, Gordon A [Benton City, WA; Brands, Michael D [Richland, WA; Bruce, James E [Schwenksville, PA; Pasa-Tolic, Ljiljana [Richland, WA; Smith, Richard D [Richland, WA

    2002-12-24

    A method whereby a mass spectra generated by a mass spectrometer is calibrated by shifting the parameters used by the spectrometer to assign masses to the spectra in a manner which reconciles the signal of ions within the spectra having equal mass but differing charge states, or by reconciling ions having known differences in mass to relative values consistent with those known differences. In this manner, the mass spectrometer is calibrated without the need for standards while allowing the generation of a highly accurate mass spectra by the instrument.

  1. Salts on Europa's surface detected by Galileo's near infrared mapping spectrometer. The NIMS Team.

    PubMed

    McCord, T B; Hansen, G B; Fanale, F P; Carlson, R W; Matson, D L; Johnson, T V; Smythe, W D; Crowley, J K; Martin, P D; Ocampo, A; Hibbitts, C A; Granahan, J C

    1998-05-22

    Reflectance spectra in the 1- to 2.5-micrometer wavelength region of the surface of Europa obtained by Galileo's Near Infrared Mapping Spectrometer exhibit distorted water absorption bands that indicate the presence of hydrated minerals. The laboratory spectra of hydrated salt minerals such as magnesium sulfates and sodium carbonates and mixtures of these minerals provide a close match to the Europa spectra. The distorted bands are only observed in the optically darker areas of Europa, including the lineaments, and may represent evaporite deposits formed by water, rich in dissolved salts, reaching the surface from a water-rich layer underlying an ice crust.

  2. Design and simulation of a semiconductor chip-based visible - NIR spectrometer for Earth observation

    NASA Astrophysics Data System (ADS)

    Coote, J.; Woolliams, E.; Fox, N.; Goodyer, I. D.; Sweeney, S. J.

    2014-03-01

    We present the development of a novel semiconductor chip-based spectrometer for calibration of Earth observation instruments. The chip follows the Solo spectroscopy approach utilising an array of microdisk resonators evanescently coupled to a central waveguide. Each resonator is tuned to select out a specific wavelength from the incoming spectrum, and forms a p-i-n junction in which current is generated when light of the correct wavelength is present. In this paper we discuss important design aspects including the choice of semiconductor material, design of semiconductor quantum well structures for optical absorption, and design and optimisation of the waveguide and resonators.

  3. Engine spectrometer probe and method of use

    NASA Technical Reports Server (NTRS)

    Barkhoudarian, Sarkis (Inventor); Kittinger, Scott A. (Inventor)

    2006-01-01

    The engine spectrometer probe and method of using the same of the present invention provides a simple engine spectrometer probe which is both lightweight and rugged, allowing an exhaust plume monitoring system to be attached to a vehicle, such as the space shuttle. The engine spectrometer probe can be mounted to limit exposure to the heat and debris of the exhaust plume. The spectrometer probe 50 comprises a housing 52 having an aperture 55 and a fiber optic cable 60 having a fiber optic tip 65. The fiber optic tip 65 has an acceptance angle 87 and is coupled to the aperture 55 so that the acceptance angle 87 intersects the exhaust plume 30. The spectrometer probe can generate a spectrum signal from light in the acceptance angle 506 and the spectrum signal can be provided to a spectrometer 508.

  4. X-ray absorption spectroscopy of aluminum z-pinch plasma with tungsten backlighter planar wire array source.

    PubMed

    Osborne, G C; Kantsyrev, V L; Safronova, A S; Esaulov, A A; Weller, M E; Shrestha, I; Shlyaptseva, V V; Ouart, N D

    2012-10-01

    Absorption features from K-shell aluminum z-pinch plasmas have recently been studied on Zebra, the 1.7 MA pulse power generator at the Nevada Terawatt Facility. In particular, tungsten plasma has been used as a semi-backlighter source in the generation of aluminum K-shell absorption spectra by placing a single Al wire at or near the end of a single planar W array. All spectroscopic experimental results were recorded using a time-integrated, spatially resolved convex potassium hydrogen phthalate (KAP) crystal spectrometer. Other diagnostics used to study these plasmas included x-ray detectors, optical imaging, laser shadowgraphy, and time-gated and time-integrated x-ray pinhole imagers. Through comparisons with previous publications, Al K-shell absorption lines are shown to be from much lower electron temperature (∼10-40 eV) plasmas than emission spectra (∼350-500 eV).

  5. Low power consumption lasers for next generation miniature optical spectrometers for trace gas analysis

    NASA Astrophysics Data System (ADS)

    Forouhar, S.; Frez, C.; Franz, K. J.; Ksendzov, A.; Qiu, Y.; Soibel, K. A.; Chen, J.; Hosoda, T.; Kipshidze, G.; Shterengas, L.; Belenky, G.

    2011-01-01

    The air quality of any manned spacecraft needs to be continuously monitored in order to safeguard the health of the crew. Air quality monitoring grows in importance as mission duration increases. Due to the small size, low power draw, and performance reliability, semiconductor laser-based instruments are viable candidates for this purpose. Achieving a minimum instrument size requires lasers with emission wavelength coinciding with the absorption of the fundamental absorption lines of the target gases, which are mostly in the 3.0-5.0 μm wavelength range. In this paper we report on our progress developing high wall plug efficiency type-I quantum-well GaSb-based diode lasers operating at room temperatures in the spectral region near 3.0-3.5 μm and quantum cascade (QC) lasers in the 4.0-5.0 μm range. These lasers will enable the development of miniature, low-power laser spectrometers for environmental monitoring of the spacecraft.

  6. Monitoring Of The Middle Atmosphere: Grille Spectrometer Experiment Results On Board SPACELAB 1 And Scientific Program Of ATLAS 1 Mission

    NASA Astrophysics Data System (ADS)

    Papineau, N.; Camy-Peyret, C.; Ackerman, Marcel E.

    1989-10-01

    Measurements of atmospheric trace gases have been performed during the first Spacelab mission on board the Space Shuttle. The principle of the observations is infrared absorption spectroscopy using the solar occultation technique. Infrared absorption spectra of NO, CO, CO2, NO2, N20, CH4 and H2O have been recorded using the Grille spectrometer developped by ONERA and IASB. From the observed spectra, vertical profiles for these molecules have been derived. The present paper summarizes the main results and compares them with computed vertical profiles from a zonally averaged model of the middle atmosphere. The scientific objectives of the second mission, Atlas 1, planned for 1990 are also presented.

  7. MEMS based digital transform spectrometers

    NASA Astrophysics Data System (ADS)

    Geller, Yariv; Ramani, Mouli

    2005-09-01

    Earlier this year, a new breed of Spectrometers based on Micro-Electro-Mechanical-System (MEMS) engines has been introduced to the commercial market. The use of these engines combined with transform mathematics, produces powerful spectrometers at unprecedented low cost in various spectral regions.

  8. Measurement of Urban Air Quality by an Open-Path Quantum Cascade Laser Absorption Spectrometer in Beijing During Summer 2008

    NASA Astrophysics Data System (ADS)

    Michel, A. P.; Liu, P. Q.; Yeung, J. K.; Zhang, Y.; Baeck, M. L.; Pan, X.; Dong, H.; Wang, Z.; Smith, J. A.; Gmachl, C. F.

    2009-05-01

    The 2008 Olympic Games focused attention on the air quality of Beijing, China and served as an important test-bed for developing, deploying, and testing new technologies for analysis of air quality and regional climate in urban environments. Poor air quality in urban locations has a significant detrimental effect on the health of residents while also impacting both regional and global climate change. As a result, there exists a great need for highly sensitive trace gas sensors for studying the atmosphere of the urban environment. Open-path remote sensors are of particular interest as they can obtain data on spatial scales similar to those used in regional climate models. Quantum cascade lasers (QCLs) can be designed for operation in the mid-infrared (mid-IR) with a central wavelength anywhere between 3 to 24 μm and made tunable over a wavelength interval of over 0.1 μm. The Quantum Cascade Laser Open-Path System (QCLOPS) is a mid-infrared laser absorption spectrometer that uses a tunable, thermoelectrically cooled, pulsed Daylight Solutions Inc. QCL for measurement of trace gases. The system is aimed at applications with path lengths ranging from approximately 0.1 to 1.0 km. The system is designed to continuously monitor multiple trace gases [water vapor (H2O), ozone (O3), ammonia (NH3), and carbon dioxide (CO2)] in the lower atmosphere. A field campaign from July to September 2008 in Beijing used QCLOPS to study trace gas concentrations before, during, and after the Olympic Games in an effort to capture changes induced by emissions reduction methods. QCLOPS was deployed at the Institute of Atmospheric Physics - Chinese Academy of Sciences on the roof of a two-story building, at an approximate distance of 2 miles from the Olympic National Stadium ("The Bird's Nest.") QCLOPS operated with an open-path round trip distance of approximately 75 m. The system ran with minimal human interference, twenty-four hours per day for the full campaign period. In order to

  9. Sample rotating turntable kit for infrared spectrometers

    DOEpatents

    Eckels, Joel Del [Livermore, CA; Klunder, Gregory L [Oakland, CA

    2008-03-04

    An infrared spectrometer sample rotating turntable kit has a rotatable sample cup containing the sample. The infrared spectrometer has an infrared spectrometer probe for analyzing the sample and the rotatable sample cup is adapted to receive the infrared spectrometer probe. A reflectance standard is located in the rotatable sample cup. A sleeve is positioned proximate the sample cup and adapted to receive the probe. A rotator rotates the rotatable sample cup. A battery is connected to the rotator.

  10. Active coherent laser spectrometer for remote detection and identification of chemicals

    NASA Astrophysics Data System (ADS)

    MacLeod, Neil A.; Weidmann, Damien

    2012-10-01

    Currently, there exists a capability gap for the remote detection and identification of threat chemicals. We report here on the development of an Active Coherent Laser Spectrometer (ACLaS) operating in the thermal infrared and capable of multi-species stand-off detection of chemicals at sub ppm.m levels. A bench top prototype of the instrument has been developed using distributed feedback mid-infrared quantum cascade lasers as spectroscopic sources. The instrument provides active eye-safe illumination of a topographic target and subsequent spectroscopic analysis through optical heterodyne detection of the diffuse backscattered field. Chemical selectivity is provided by the combination of the narrow laser spectral bandwidth (typically < 2 MHz) and frequency tunability that allows the recording of the full absorption spectrum of any species within the instrument line of sight. Stand-off detection at distances up to 12 m has been demonstrated on light molecules such as H2O, CH4 and N2O. A physical model of the stand-off detection scenario including ro-vibrational molecular absorption parameters was used in conjunction with a fitting algorithm to retrieve quantitative mixing ratio information on multiple absorbers.

  11. Fabrication and study of cylindrical scintillation counters of the ARES spectrometer

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

    Baranov, V.A.; Evtukhovich, P.G.; Korenchenko, S.M.

    A method is described for fabricating 600 x 87 x 5 mm plastic scintillation counters which are constituent elements of a 673 mm in diameter cylindrical hodoscope. Results of investigations into the amplitude and temporal characteristics of a separate scintillation are presented. Light losses in the transitional and main lightguides were determined primarily by the absorption length of the organic glass. The time resolution of the counter with the beta source placed at the center of the scintillator equaled 1 nsec; the velocity of propagation of light in the scintillator equals 12.1 cm/nsec. The ARES spectrometer detects electrons and gammamore » rays under conditions of high meson-stopping intensity and will be used for pion and muon rare decay studies.« less

  12. Electro-Optical Imaging Fourier-Transform Spectrometer

    NASA Technical Reports Server (NTRS)

    Chao, Tien-Hsin; Zhou, Hanying

    2006-01-01

    An electro-optical (E-O) imaging Fourier-transform spectrometer (IFTS), now under development, is a prototype of improved imaging spectrometers to be used for hyperspectral imaging, especially in the infrared spectral region. Unlike both imaging and non-imaging traditional Fourier-transform spectrometers, the E-O IFTS does not contain any moving parts. Elimination of the moving parts and the associated actuator mechanisms and supporting structures would increase reliability while enabling reductions in size and mass, relative to traditional Fourier-transform spectrometers that offer equivalent capabilities. Elimination of moving parts would also eliminate the vibrations caused by the motions of those parts. Figure 1 schematically depicts a traditional Fourier-transform spectrometer, wherein a critical time delay is varied by translating one the mirrors of a Michelson interferometer. The time-dependent optical output is a periodic representation of the input spectrum. Data characterizing the input spectrum are generated through fast-Fourier-transform (FFT) post-processing of the output in conjunction with the varying time delay.

  13. Updates in the IR responsivity of VIR, the spectrometer of the Dawn mission.

    NASA Astrophysics Data System (ADS)

    Ammannito, Eleonora; Mc Cord, Thomas B.; De Sanctis, Maria Cristina.; Combe, Jean-Philippe

    VIR-MS (Visual and Infrared Mapping Spectrometer) is the imaging spectrometer of the Dawn mission (1,2). Here, first we describe the computation of a new instrument responsivity based on the internal calibration data acquired during the operations at Vesta, and then we describe its effect on the dataset and on the results published so far. VIR-MS was built in Italy by a scientific-industrial (IAPS/INAF in Rome (Italy) and Selex ES in Campi Bisenzio (Fi, Italy)) consortium financially supported by the Italian Space Agency. VIR-MS is an high spatial resolution spectrometer (FOV of 64mrad, IFOV of 250 µrad) in the 0.25-5 µm range with an IFOV of 250 µrad and a spectral sampling of about 2 nm in the visible range and 10 nm in the IR range. The results of the on-ground calibration held in the Selex calibration facility in September 2005 were already presented and discussed in a paper (2). This version has been used to calibrate the data available on the Planetary Data System (PDS) Small Bodies Node, dataset used in all the papers published so far. However, after the operations at the asteroid Vesta, we have identified some artifacts in the instrument responsivity in the 2.5-3.5 µm region, which is where several absorption bands of OH and H2O occur. Those artifacts were systematic, and therefore they did not prevent the detection of relative spectral variations associated to OH and H2O. Actually, the only paper published in which are discussed spectra in this range (3) used a different calibration method described in the paper itself. This method used a simple correction of the response function based on an empirical calibration correction that is appropriate to recover the signal in that specific range. However, the absolute absorption band depth of OH and H2O could not be calculated. To compute a new instrument responsivity we used the internal lamp of the spectrometer. This lamp, made of a tungsten filament, is characterized by a blackbody-like emission at about

  14. Broadband, high-resolution investigation of advanced absorption line shapes at high temperature

    NASA Astrophysics Data System (ADS)

    Schroeder, Paul J.; Cich, Matthew J.; Yang, Jinyu; Swann, William C.; Coddington, Ian; Newbury, Nathan R.; Drouin, Brian J.; Rieker, Gregory B.

    2017-08-01

    Spectroscopic studies of planetary atmospheres and high-temperature processes (e.g., combustion) require absorption line-shape models that are accurate over extended temperature ranges. To date, advanced line shapes, like the speed-dependent Voigt and Rautian profiles, have not been tested above room temperature with broadband spectrometers. We investigate pure water vapor spectra from 296 to 1305 K acquired with a dual-frequency comb spectrometer spanning from 6800 to 7200 c m-1 at a point spacing of 0.0033 c m-1 and absolute frequency accuracy of <3.3 ×10-6c m-1 . Using a multispectral fitting analysis, we show that only the speed-dependent Voigt accurately models this temperature range with a single power-law temperature-scaling exponent for the broadening coefficients. Only the data from the analysis using this profile fall within theoretical predictions, suggesting that this mechanism captures the dominant narrowing physics for these high-temperature conditions.

  15. The total spectral radiant flux calibration using a spherical spectrometer at National Institute of Metrology China

    NASA Astrophysics Data System (ADS)

    Zhao, Weiqiang; Liu, Hui; Liu, Jian

    2016-11-01

    At present day, in the field of lighting the incandescent lamps are phasing out. The solid state lighting products, i.e. LED, and the related market are developing very fast in China for its promising application, due to the energy-saving and the colorful features. For the quality control and the commercial trade purpose, it is highly necessary to measure the optical parameters of LED light sources with a fast, easy and affordable facility. Therefore, more test labs use the spherical spectrometer to measure LED. The quasi- monochrome of LED and the V(lambda) of silicon photodetector mismatch problem is reduced or avoided, because the total spectral radiant flux (TSRF) is measured, and all the optical parameters are calculate from the TSRF. In such a way, the spherical spectrometer calibration requires TSRF standard lamps instead of the traditional total flux standard lamps. National Institute of Metrology China (NIM) has studied and developed the facilities for TSRF measurement and provides related calibration services. This paper shows the TSRF standard lamp calibration procedure using a spherical spectrometer in every-day calibration and its traceable link to the primary SI unit at NIM. The sphere is of 1.5 m diameter, and installed with a spectrometer and a silicon photodetector. It also shows the detail of data process, such as the spectral absorption correction method and the calculation of the result derived from the spectral readings. The TSRF calibration covers the spectra range of 350 nm to 1050 nm, with a measurement uncertainty of 3.6% 1.8% (k=2).

  16. Imaging IR spectrometer, phase 2

    NASA Technical Reports Server (NTRS)

    Gradie, Jonathan; Lewis, Ralph; Lundeen, Thomas; Wang, Shu-I

    1990-01-01

    The development is examined of a prototype multi-channel infrared imaging spectrometer. The design, construction and preliminary performance is described. This instrument is intended for use with JPL Table Mountain telescope as well as the 88 inch UH telescope on Mauna Kea. The instrument is capable of sampling simultaneously the spectral region of 0.9 to 2.6 um at an average spectral resolution of 1 percent using a cooled (77 K) optical bench, a concave holographic grating and a special order sorting filter to allow the acquisition of the full spectral range on a 128 x 128 HgCdTe infrared detector array. The field of view of the spectrometer is 0.5 arcsec/pixel in mapping mode and designed to be 5 arcsec/pixel in spot mode. The innovative optical design has resulted in a small, transportable spectrometer, capable of remote operation. Commercial applications of this spectrometer design include remote sensing from both space and aircraft platforms as well as groundbased astronomical observations.

  17. NIST Calibration of a Neutron Spectrometer ROSPEC.

    PubMed

    Heimbach, Craig

    2006-01-01

    A neutron spectrometer was acquired for use in the measurement of National Institute of Standards and Technology neutron fields. The spectrometer included options for the measurement of low and high energy neutrons, for a total measurement range from 0.01 eV up to 17 MeV. The spectrometer was evaluated in calibration fields and was used to determine the neutron spectrum of an Americium-Beryllium neutron source. The calibration fields used included bare and moderated (252)Cf, monoenergetic neutron fields of 2.5 MeV and 14 MeV, and a thermal-neutron beam. Using the calibration values determined in this exercise, the spectrometer gives a good approximation of the neutron spectrum, and excellent values for neutron fluence, for all NIST calibration fields. The spectrometer also measured an Americium-Beryllium neutron field in a NIST exposure facility and determined the field quite well. The spectrometer measured scattering effects in neutron spectra which previously could be determined only by calculation or integral measurements.

  18. Study for the dispersion of double-diffraction spectrometers

    NASA Astrophysics Data System (ADS)

    Pang, Yajun; Zhang, Yinxin; Yang, Huaidong; Huang, Zhanhua; Xu, Mingming; Jin, Guofan

    2018-01-01

    Double-cascade spectrometers and double-pass spectrometers can be uniformly called double-diffraction spectrometers. In current double-diffraction spectrometers design theory, the differences of the incident angles in the second diffraction are ignored. There is a significant difference between the design in theory and the actual result. In this study, based on the geometries of the double-diffraction spectrometers, we strictly derived the theoretical formulas of their dispersion. By employing the ZEMAX simulation software, verification of our theoretical model is implemented, and the simulation results show big agreement with our theoretical formulas. Based on the conclusions, a double-pass spectrometer was set up and tested, and the experiment results agree with the theoretical model and the simulation.

  19. Saturated absorption in a rotational molecular transition at 2.5 THz using a quantum cascade laser

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

    Consolino, L., E-mail: luigi.consolino@ino.it; Campa, A.; Ravaro, M.

    2015-01-12

    We report on the evidence of saturation effects in a rotational transition of CH{sub 3}OH around 2.5 THz, induced by a free-running continuous-wave quantum cascade laser (QCL). The QCL emission is used for direct-absorption spectroscopy experiments, allowing to study the dependence of the absorption coefficient on gas pressure and laser intensity. A saturation intensity of 25 μW/mm{sup 2}, for a gas pressure of 17 μbar, is measured. This result represents the initial step towards the implementation of a QCL-based high-resolution sub-Doppler THz spectroscopy, which is expected to improve by orders of magnitude the precision of THz spectrometers.

  20. CUVE - Cubesat UV Experiment: Unveil Venus' UV Absorber with Cubesat UV Mapping Spectrometer

    NASA Astrophysics Data System (ADS)

    Cottini, V.; Aslam, S.; D'Aversa, E.; Glaze, L.; Gorius, N.; Hewagama, T.; Ignatiev, N.; Piccioni, G.

    2017-09-01

    Our Venus mission concept Cubesat UV Experiment (CUVE) is one of ten proposals selected for funding by the NASA PSDS3 Program - Planetary Science Deep Space SmallSat Studies. CUVE concept is to insert a CubeSat spacecraft into a Venusian orbit and perform remote sensing of the UV spectral region using a high spectral resolution point spectrometer to resolve UV molecular bands, observe nightglow, and characterize the unidentified main UV absorber. The UV spectrometer is complemented by an imaging UV camera with multiple bands in the UV absorber main band range for contextual imaging. CUVE Science Objectives are: the nature of the "Unknown" UV-absorber; the abundances and distributions of SO2 and SO at and above Venus's cloud tops and their correlation with the UV absorber; the atmospheric dynamics at the cloud tops, structure of upper clouds and wind measurements from cloud-tracking; the nightglow emissions: NO, CO, O2. This mission will therefore be an excellent platform to study Venus' cloud top atmospheric properties where the UV absorption drives the planet's energy balance. CUVE would complement past, current and future Venus missions with conventional spacecraft, and address critical science questions cost effectively.

  1. Study on a liquid-moderator-based neutron spectrometer for BNCT-Development and experimental test of the prototype spectrometer

    NASA Astrophysics Data System (ADS)

    Tamaki, S.; Sato, F.; Murata, I.

    2017-10-01

    Boron neutron capture therapy (BNCT) is known to be an effective radiation cancer therapy that requires neutron irradiation. A neutron field generated by an accelerator-based neutron source has various energy spectra, and it is necessary to evaluate the neutron spectrum in the treatment field. However, the method used to measure the neutron spectrum in the treatment field is not well established, and many researchers are making efforts to improve the spectrometers used. In the present study, we developed a prototype of a new neutron spectrometer that can measure the neutron spectra more accurately and precisely. The spectrometer is based on the same theory as that of the Bonner sphere spectrometer, and it uses a liquid moderator and an absorber. By carrying out an experimental test of the developed spectrometer, we finally revealed the problems and necessary conditions of the prototype detector.

  2. Effects of spectrometer band pass, sampling, and signal-to-noise ratio on spectral identification using the Tetracorder algorithm

    USGS Publications Warehouse

    Swayze, G.A.; Clark, R.N.; Goetz, A.F.H.; Chrien, T.H.; Gorelick, N.S.

    2003-01-01

    Estimates of spectrometer band pass, sampling interval, and signal-to-noise ratio required for identification of pure minerals and plants were derived using reflectance spectra convolved to AVIRIS, HYDICE, MIVIS, VIMS, and other imaging spectrometers. For each spectral simulation, various levels of random noise were added to the reflectance spectra after convolution, and then each was analyzed with the Tetracorder spectra identification algorithm [Clark et al., 2003]. The outcome of each identification attempt was tabulated to provide an estimate of the signal-to-noise ratio at which a given percentage of the noisy spectra were identified correctly. Results show that spectral identification is most sensitive to the signal-to-noise ratio at narrow sampling interval values but is more sensitive to the sampling interval itself at broad sampling interval values because of spectral aliasing, a condition when absorption features of different materials can resemble one another. The band pass is less critical to spectral identification than the sampling interval or signal-to-noise ratio because broadening the band pass does not induce spectral aliasing. These conclusions are empirically corroborated by analysis of mineral maps of AVIRIS data collected at Cuprite, Nevada, between 1990 and 1995, a period during which the sensor signal-to-noise ratio increased up to sixfold. There are values of spectrometer sampling and band pass beyond which spectral identification of materials will require an abrupt increase in sensor signal-to-noise ratio due to the effects of spectral aliasing. Factors that control this threshold are the uniqueness of a material's diagnostic absorptions in terms of shape and wavelength isolation, and the spectral diversity of the materials found in nature and in the spectral library used for comparison. Array spectrometers provide the best data for identification when they critically sample spectra. The sampling interval should not be broadened to

  3. Mathematical Simulation for Integrated Linear Fresnel Spectrometer Chip

    NASA Technical Reports Server (NTRS)

    Park, Yeonjoon; Yoon, Hargoon; Lee, Uhn; King, Glen C.; Choi, Sang H.

    2012-01-01

    A miniaturized solid-state optical spectrometer chip was designed with a linear gradient-gap Fresnel grating which was mounted perpendicularly to a sensor array surface and simulated for its performance and functionality. Unlike common spectrometers which are based on Fraunhoffer diffraction with a regular periodic line grating, the new linear gradient grating Fresnel spectrometer chip can be miniaturized to a much smaller form-factor into the Fresnel regime exceeding the limit of conventional spectrometers. This mathematical calculation shows that building a tiny motionless multi-pixel microspectrometer chip which is smaller than 1 cubic millimter of optical path volume is possible. The new Fresnel spectrometer chip is proportional to the energy scale (hc/lambda), while the conventional spectrometers are proportional to the wavelength scale (lambda). We report the theoretical optical working principle and new data collection algorithm of the new Fresnel spectrometer to build a compact integrated optical chip.

  4. Geodetic Mobil Solar Spectrometer for JASON Altimeter Satellite Calibration

    NASA Astrophysics Data System (ADS)

    Somieski, A.; Buerki, B.; Geiger, A.; Kahle, H.-G.; Becker-Ross, H.; Florek, S.; Okruss, M.

    Atmospheric water vapor is a crucial factor in achieving highest accuracies for space geodetic measurements. Water vapor causes a delay of the propagation time of the altimeter satellite signal, which propagates into errors for the determination of surface heights. Knowledge of the precipitable water vapor (PW) enables a tropospheric correction of the satellite signal. Therefore, different remote sensing techniques have been pursued to measure the PW continuously. The prototype Geodetic Mobil Solar Spectrometer (GEMOSS) was developed at the Geodesy and Geodynamics Laboratory (GGL, ETH Zurich) in cooperation with the Institute of Spectrochemistry and Applied Spectroscopy (ISAS) (Berlin, Germany). A new optical approach allows the simultaneous measurement of numerous single absorption lines of water vapor in the wide range between 728 nm and 915 nm. The large number of available absorption lines increases the accuracy of the absolute PW retrievals considerably. GEMOSS has been deployed during two campaigns in Greece in the framework of the EU-project GAVDOS, which deals with the calibration of the altimeter satellite JASON. During the overfly of JASON, the ground-based determination of PW enables the correction of the satellite measurements due to tropospheric water vapor. Comparisons with radiometer and radiosondes data allow to assess the accuracy and reliability of GEMOSS. The instrumental advancement of GEMOSS is presented together with the results of the campaigns carried out.

  5. Electro-optic Imaging Fourier Transform Spectrometer

    NASA Technical Reports Server (NTRS)

    Chao, Tien-Hsin

    2005-01-01

    JPL is developing an innovative compact, low mass, Electro-Optic Imaging Fourier Transform Spectrometer (E-O IFTS) for hyperspectral imaging applications. The spectral region of this spectrometer will be 1 - 2.5 micron (1000-4000/cm) to allow high-resolution, high-speed hyperspectral imaging applications. One application will be the remote sensing of the measurement of a large number of different atmospheric gases simultaneously in the same airmass. Due to the use of a combination of birefringent phase retarders and multiple achromatic phase switches to achieve phase delay, this spectrometer is capable of hyperspectral measurements similar to that of the conventional Fourier transform spectrometer but without any moving parts. In this paper, the principle of operations, system architecture and recent experimental progress will be presented.

  6. Electro-optic Imaging Fourier Transform Spectrometer

    NASA Technical Reports Server (NTRS)

    Chao, Tien-Hsin

    2005-01-01

    JPL is developing an innovative compact, low mass, Electro-Optic Imaging Fourier Transform Spectrometer (E-0IFTS) for hyperspectral imaging applications. The spectral region of this spectrometer will be 1 - 2.5 pm (1000 -4000 cm-') to allow high-resolution, high-speed hyperspectral imaging applications [l-51. One application will be theremote sensing of the measurement of a large number of different atmospheric gases simultaneously in the sameairmass. Due to the use of a combination of birefiingent phase retarders and multiple achromatic phase switches toachieve phase delay, this spectrometer is capable of hyperspectral measurements similar to that of the conventionalFourier transform spectrometer but without any moving parts. In this paper, the principle of operations, systemarchitecture and recent experimental progress will be presen.

  7. Cassini Visual and Infrared Mapping Spectrometer observations of Iapetus: Detection of CO2

    USGS Publications Warehouse

    Buratti, B.J.; Cruikshank, D.P.; Brown, R.H.; Clark, R.N.; Bauer, J.M.; Jaumann, R.; McCord, T.B.; Simonelli, D.P.; Hibbitts, C.A.; Hansen, G.B.; Owen, T.C.; Baines, K.H.; Bellucci, G.; Bibring, J.-P.; Capaccioni, F.; Cerroni, P.; Coradini, A.; Drossart, P.; Formisano, V.; Langevin, Y.; Matson, D.L.; Mennella, V.; Nelson, R.M.; Nicholson, P.D.; Sicardy, B.; Sotin, Christophe; Roush, T.L.; Soderlund, K.; Muradyan, A.

    2005-01-01

    The Visual and Infrared Mapping Spectrometer (VIMS) instrument aboard the Cassini spacecraft obtained its first spectral map of the satellite lapetus in which new absorption bands are seen in the spectra of both the low-albedo hemisphere and the H2O ice-rich hemisphere. Carbon dioxide is identified in the low-albedo material, probably as a photochemically produced molecule that is trapped in H2O ice or in some mineral or complex organic solid. Other absorption bands are unidentified. The spectrum of the low-albedo hemisphere is satisfactorily modeled with a combination of organic tholin, poly-HCN, and small amounts of H2O ice and Fe 2O3. The high-albedo hemisphere is modeled with H 2O ice slightly darkened with tholin. The detection of CO2 in the low-albedo material on the leading hemisphere supports the contention that it is carbon-bearing material from an external source that has been swept up by the satellite's orbital motion. ?? 2005. The American Astronomical Society. All rights reserved.

  8. Combined raman spectrometer/laser-induced breakdown spectrometer design concept

    NASA Astrophysics Data System (ADS)

    Bazalgette Courrèges-Lacoste, Gregory; Ahlers, Berit; Boslooper, Erik; Rull-Perez, Fernando; Maurice, Sylvestre

    2017-11-01

    Amongst the different instruments that have been preselected to be on-board the Pasteur payload on ExoMars is the Raman/ Laser Induced Breakdown Spectroscopy (LIBS) instrument. Raman spectroscopy and LIBS will be integrated into a single instrument sharing many hardware commonalities. An international team under the lead of TNO has been gathered to produce a design concept for a combined Raman Spectrometer/ LIBS Elegant Bread-Board (EBB). The instrument is based on a specifically designed extremely compact spectrometer with high resolution over a large wavelength range, suitable for both Raman spectroscopy and LIBS measurements. Low mass, size and resources are the main drivers of the instrument's design concept. The proposed design concept, realization and testing programme for the combined Raman/ LIBS EBB is presented as well as background information on Raman and LIBS.

  9. Airborne Remote Earth Sensing (ARES) Program: an operational airborne MWIR imaging spectrometer and applications

    NASA Astrophysics Data System (ADS)

    Bishop, Kevin D.; Diestel, Michael J.

    1996-11-01

    Since 1993, the Airborne Remote Earth Sensing (ARES) Program has collected a wide variety of mid-wave infrared hyperspectral data on an interesting assortment of atmospheric, geologic, urban and chemical emission/absorption features. Flown in NASA's high altitude WB-57F aircraft, the ARES sensor is a 75 channel cryo-cooled prism spectrometer covering the 2 - 6 micrometers spectral region, and is capable of up or down-looking measurements over a wide range of collection geometries. Sensor characteristics, pointing capabilities, and overall performance are discussed. Highlights from some of the recent data collections, such as the 1993 and 95 thermal mapping of the active lava flow areas from the Kilauea volcano; the 1993 collection of the direct solar specular reflection off high altitude (ice) cloud layers over West Texas; upper atmospheric H2O vapor sounding using the 6 micrometers solar absorption spectra; Sulfur Dioxide detection from a coal burning power plant in Page, AZ (SO2 in emission) and from the Pu'u O'o vent of the Kilauea volcano (SO2 in absorption); and MWIR imagery from various terrestrial and urban background scenes, including West Los Angeles, and the Capitol area of Washington, D.C. Supporting spectral analysis and radiometric modeling are presented.

  10. Performance of the Chicago Water Isotope Spectrometer in the UTLS during the Asian Monsoon

    NASA Astrophysics Data System (ADS)

    Gaeta, D. C.; Clouser, B.; Sarkozy, L.; Singer, C. E.; Moyer, E. J.

    2017-12-01

    The preferential condensation of water vapor isotopologues makes the isotopic composition of water vapor a useful tracer of the processes responsible for the distribution of water in the UTLS, but the UTLS also offers particular challenges for its measurement. We report here on the field performance of a new instrument designed for measurement of HDO and H2O in the UTLS region: the Chicago Water Isotope Spectrometer (Chi-WIS). Chi-WIS is a laser-based infrared absorption spectrometer at 2.65 μm that uses a high-reflectivity optical cavity to obtain 6 km of effective path length, allowing sensitive measurements of scarce molecules. During the 2017 StratoClim aircraft campaign in Kathmandu, Nepal, Chi-WIS flew aboard the M-55 Geophysica high-altitude research aircraft in a series of flights to probe the Asian Monsoon. Preliminary results show in-flight performance consistent with laboratory performance and the achievement of design targets necessary to reach UTLS science goals. Residual noise on spectra is stable across flights at 4-5x10-4 with 1 second averaging (i.e. absorption depth of .04-.05%); the instrument is robust in terms of alignment and shows no evidence of optical resonances. The resulting measurement precision is as expected from these characteristics. Because we use a relatively strong water line, the water vapor measurement is extremely precise: constant-altitude flight legs in the stratosphere at 4 ppm H2O show 1 s standard deviation 0.03 ppmv for 1 s averaging, and 0.08 ppbv for HDO with 10 s averaging. We show comparisons with other StratoClim instruments and examples of how these measurements resolve scientifically relevant atmospheric features.

  11. Exploration of Mars in SPICAM-IR experiment onboard the Mars-Express spacecraft: 1. Acousto-optic spectrometer SPICAM-IR

    NASA Astrophysics Data System (ADS)

    Korablev, O. I.; Bertaux, J. L.; Kalinnikov, Yu. K.; Fedorova, A. A.; Moroz, V. I.; Kiselev, A. V.; Stepanov, A. V.; Grigoriev, A. V.; Zhegulev, V. S.; Rodin, A. V.; Dimarellis, E.; Dubois, J. P.; Reberac, A.; van Ransbeeck, E.; Gondet, B.

    2006-07-01

    The acousto-optic spectrometer of the near infrared range, which is a part of the spectrometer SPICAM onboard the Mars-Express spacecraft, began to operate in the orbit of Mars in January 2004. In the SPICAM experiment, a spectrometer on the basis of an acousto-optic filter was used for the first time to investigate other planets. During one and a half years of operation, the IR channel of SPICAM obtained more than half a million spectra in the 1-1.7 μm range with a resolving power of more than 1500 in different modes of observation: limb, nadir, and solar eclipses. The main goal of the experiment is to study the content of water vapor in the Martian atmosphere by measuring the absorption spectrum in the 1.38 μm band. Characteristics of the instrument (high spectral resolution and signal-to-noise ratio) allow one to solve a number of additional scientific problems including the study of ozone distribution by emission of singlet oxygen (O2 1Δg), detection of the water and carbonic dioxide ices, and also the study of the vertical distribution and optical characteristics of aerosol in the Martian atmosphere. We present a description of the instrument, the results of its ground and in-flight calibrations, and a brief survey of the basic scientific results obtained by the SPICAM spectrometer during a year-and-half of operation.

  12. Functionalizing a Tapered Microcavity as a Gas Cell for On-Chip Mid-Infrared Absorption Spectroscopy

    PubMed Central

    Mandon, Julien; Harren, Frans J. M.; Wolffenbuttel, Reinoud F.

    2017-01-01

    Increasing demand for field instruments designed to measure gas composition has strongly promoted the development of robust, miniaturized and low-cost handheld absorption spectrometers in the mid-infrared. Efforts thus far have focused on miniaturizing individual components. However, the optical absorption path that the light beam travels through the sample defines the length of the gas cell and has so far limited miniaturization. Here, we present a functionally integrated linear variable optical filter and gas cell, where the sample to be measured is fed through the resonator cavity of the filter. By using multiple reflections from the mirrors on each side of the cavity, the optical absorption path is elongated from the physical μm-level to the effective mm-level. The device is batch-fabricated at the wafer level in a CMOS-compatible approach. The optical performance is analyzed using the Fizeau interferometer model and demonstrated with actual gas measurements. PMID:28878167

  13. Ring-patterned plasmonic photonic crystal thermal light source for miniaturized near-infrared spectrometers

    NASA Astrophysics Data System (ADS)

    Labib, Shady R.; Elsayed, Ahmed A.; Sabry, Yasser M.; Khalil, Diaa

    2018-02-01

    There is a growing number of spectroscopy applications in the near-infrared (NIR) range including gas sensing, food analysis, pharmaceutical and industrial applications that requires highly efficient, more compact and low-cost miniaturized spectrometers. One of the key components for such systems is the wideband light source that can be fabricated using Silicon technology and hence integrated with other components on the same chip. In this work, we report a ring-patterned plasmonic photonic crystal (PC) thermal light source for miniaturized near-infrared spectrometers. The design is based on silicon and tuned to achieve wavelength selectivity in the emitted spectrum. The design is optimized by using Rigorous Coupled-Wave Analysis (RCWA) simulation, which is used to compute the power reflectance and transmittance that are used to predict the emissivity of the structure. The design consists of a PC of silicon rings coated with platinum. The period of the structure is about 2 μm and the silicon is highly-doped with n-type doping level in the order of 1019-1020 cm-3 to enhance the free-carrier absorption. The ring etching depth, diameter and shell thickness are optimized to increase its emissivity within a specific wavelength range of interest. The simulation results show an emissivity exceeding 0.9 in the NIR range up to 2.5 μm, while the emissivity is decreased significantly for longer wavelengths suppressing the emission out of the range of interest, and hence increasing the efficiency for the source. The reported results open the door for black body radiation engineering in integrated silicon sources for spectrometer miniaturization.

  14. SUB 1-Millimeter Size Fresnel Micro Spectrometer

    NASA Technical Reports Server (NTRS)

    Park, Yeonjoon; Koch, Laura; Song, Kyo D.; Park, Sangloon; King, Glen; Choi, Sang

    2010-01-01

    An ultra-small micro spectrometer with less than 1mm diameter was constructed using Fresnel diffraction. The fabricated spectrometer has a diameter of 750 nmicrometers and a focal length of 2.4 mm at 533nm wavelength. The micro spectrometer was built with a simple negative zone plate that has an opaque center with an ecliptic shadow to remove the zero-order direct beam to the aperture slit. Unlike conventional approaches, the detailed optical calculation indicates that the ideal spectral resolution and resolving power do not depend on the miniaturized size but only on the total number of rings. We calculated 2D and 3D photon distribution around the aperture slit and confirmed that improved micro-spectrometers below 1mm size can be built with Fresnel diffraction. The comparison between mathematical simulation and measured data demonstrates the theoretical resolution, measured performance, misalignment effect, and improvement for the sub-1mm Fresnel micro-spectrometer. We suggest the utilization of an array of micro spectrometers for tunable multi-spectral imaging in the ultra violet range.

  15. Ultraviolet-Absorption Spectroscopic Biofilm Monitor

    NASA Technical Reports Server (NTRS)

    Micheels, Ronald H.

    2004-01-01

    An ultraviolet-absorption spectrometer system has been developed as a prototype instrument to be used in continuous, real-time monitoring to detect the growth of biofilms. Such monitoring is desirable because biofilms are often harmful. For example, biofilms in potable-water and hydroponic systems act as both sources of pathogenic bacteria that resist biocides and as a mechanism for deterioration (including corrosion) of pipes. Biofilms formed from several types of hazardous bacteria can thrive in both plant-growth solutions and low-nutrient media like distilled water. Biofilms can also form in condensate tanks in air-conditioning systems and in industrial heat exchangers. At present, bacteria in potable-water and plant-growth systems aboard the space shuttle (and previously on the Mir space station) are monitored by culture-plate counting, which entails an incubation period of 24 to 48 hours for each sample. At present, there are no commercially available instruments for continuous monitoring of biofilms in terrestrial or spaceborne settings.

  16. Development of Calorimetric Particle Spectrometer and Measurement of Specific Heat at Low Temperature.

    NASA Astrophysics Data System (ADS)

    Zhou, Jun-Wei

    1991-02-01

    A dilution refrigerator has been put into work from 30 mK to 300 K to study bolometer characteristics relevant to its potential use as a high resolution X-ray and alpha, beta, gamma particle spectrometer. Tests of the energy deposited in the detector by measuring the temperature rise following absorption of individual nuclear particles or X- or gamma-rays have been done. Essential studies were made of electromagnetic and acoustic noise. A composite-composite bolometer fabricated by the group of N. Coron (Institute of Space Astrophysics, France), with whom we collaborate, was used. This design allows the separate optimization of the absorber and thermistor, and avoids problems with absorption inhomogeneties. A FWHM resolution of 10.5 KeV for 5 to 6 MeV alpha spectra was obtained. This resolution exceeds the best obtainable with surface barrier semiconductor detectors. A broad spectrum recording simultaneously gamma-rays, beta and alpha particles from 15 KeV to 6 MeV was obtained with the same bolometer cooled below 0.1 K. Other bolometers were also tested. 6 KeV X-rays have been observed with a resolution of 472 eV. The bolometers were also used for determination of specific heat of the sapphire at low temperatures. Assuming a specific heat C = AT^3, we find in a 2.3 g sample A ~eq 1.4 times 10^{-8} J/Kcdotg from T = 0.1 K to T = 0.4 K. A discussion of the systematic errors in determining A is given. From our measurements, it was determined that a bolometer designed for a future possible neutrino mass measurement would have a resolution of 7.5 eV at 80 mK under optimal operation. Since tritium was implanted in this detector, systematic errors associated with electron spectrometer beta spectrum measurements can be, in principle, avoided.

  17. Method of multiplexed analysis using ion mobility spectrometer

    DOEpatents

    Belov, Mikhail E [Richland, WA; Smith, Richard D [Richland, WA

    2009-06-02

    A method for analyzing analytes from a sample introduced into a Spectrometer by generating a pseudo random sequence of a modulation bins, organizing each modulation bin as a series of submodulation bins, thereby forming an extended pseudo random sequence of submodulation bins, releasing the analytes in a series of analyte packets into a Spectrometer, thereby generating an unknown original ion signal vector, detecting the analytes at a detector, and characterizing the sample using the plurality of analyte signal subvectors. The method is advantageously applied to an Ion Mobility Spectrometer, and an Ion Mobility Spectrometer interfaced with a Time of Flight Mass Spectrometer.

  18. Non-destructive plant health sensing using absorption spectroscopy

    NASA Technical Reports Server (NTRS)

    Bledsoe, Jim; Manukian, Ara; Pearce, Michael; Weiss, Lee

    1988-01-01

    The sensor group of the 1988 EGM 4001 class, working on NASA's Controlled Ecological Life Support Systems (CELSS) project, investigated many different plant health indicators and the technologies used to test them. The project selected by the group was to measure chlorophyll levels using absorption spectroscopy. The spectrometer measures the amount of chlorophyll in a leaf by measuring the intensity of light of a specific wavelength that is passed through a leaf. The three wavelengths of light being used corresponded to the near-IR absorption peaks of chlorophyll a, chlorophyll b, and chlorophyll-free structures. Experimentation showed that the sensor is indeed measuring levels of chlorophyll a and b and their changes before the human eye can see any changes. The detector clamp causes little damage to the leaf and will give fairly accurate readings on similar locations on a leaf, freeing the clamp from having to remain on the same spot of a leaf for all measurements. External light affects the readings only slightly so that measurements may be taken in light or dark environments. Future designs and experimentation will concentrate on reducing the size of the sensor and adapting it to a wider range of plants.

  19. Advancements, measurement uncertainties, and recent comparisons of the NOAA frost point hygrometer.

    PubMed

    Hall, Emrys G; Jordan, Allen F; Hurst, Dale F; Oltmans, Samuel J; Vömel, Holger; Kühnreich, Benjamin; Ebert, Volker

    2016-01-01

    The NOAA frost point hygrometer (FPH) is a balloon-borne instrument flown monthly at three sites to measure water vapor profiles up to 28 km. The FPH record from Boulder, Colorado, is the longest continuous stratospheric water vapor record. The instrument has an uncertainty in the stratosphere that is < 6 % and up to 12 % in the troposphere. A digital microcontroller version of the instrument improved upon the older versions in 2008 with sunlight filtering, better frost control, and resistance to radio frequency interference (RFI). A new thermistor calibration technique was implemented in 2014, decreasing the uncertainty in the thermistor calibration fit to less than 0.01 °C over the full range of frost - or dew point temperatures (-93 to +20 °C) measured during a profile. Results from multiple water vapor intercomparisons are presented, including the excellent agreement between the NOAA FPH and the direct tunable diode laser absorption spectrometer (dTDLAS) MC-PicT-1.4 during AquaVIT-2 chamber experiments over 6 days that provides confidence in the accuracy of the FPH measurements. Dual instrument flights with two FPHs or an FPH and a cryogenic frost point hygrometer (CFH) also show good agreement when launched on the same balloon. The results from these comparisons demonstrate the high level of accuracy of the NOAA FPH.

  20. Advancements, measurement uncertainties, and recent comparisons of the NOAA frost point hygrometer

    PubMed Central

    Hall, Emrys G.; Jordan, Allen F.; Hurst, Dale F.; Oltmans, Samuel J.; Vömel, Holger; Kühnreich, Benjamin; Ebert, Volker

    2017-01-01

    The NOAA frost point hygrometer (FPH) is a balloon-borne instrument flown monthly at three sites to measure water vapor profiles up to 28 km. The FPH record from Boulder, Colorado, is the longest continuous stratospheric water vapor record. The instrument has an uncertainty in the stratosphere that is < 6 % and up to 12 % in the troposphere. A digital microcontroller version of the instrument improved upon the older versions in 2008 with sunlight filtering, better frost control, and resistance to radio frequency interference (RFI). A new thermistor calibration technique was implemented in 2014, decreasing the uncertainty in the thermistor calibration fit to less than 0.01 °C over the full range of frost – or dew point temperatures (−93 to +20 °C) measured during a profile. Results from multiple water vapor intercomparisons are presented, including the excellent agreement between the NOAA FPH and the direct tunable diode laser absorption spectrometer (dTDLAS) MC-PicT-1.4 during AquaVIT-2 chamber experiments over 6 days that provides confidence in the accuracy of the FPH measurements. Dual instrument flights with two FPHs or an FPH and a cryogenic frost point hygrometer (CFH) also show good agreement when launched on the same balloon. The results from these comparisons demonstrate the high level of accuracy of the NOAA FPH. PMID:28845201

  1. Innovative optical spectrometers for ice core sciences and atmospheric monitoring at polar regions

    NASA Astrophysics Data System (ADS)

    Grilli, Roberto; Alemany, Olivier; Chappellaz, Jérôme; Desbois, Thibault; Faïn, Xavier; Kassi, Samir; Kerstel, Erik; Legrand, Michel; Marrocco, Nicola; Méjean, Guillaume; Preunkert, Suzanne; Romanini, Daniele; Triest, Jack; Ventrillard, Irene

    2015-04-01

    In this talk recent developments accomplished from a collaboration between the Laboratoire Interdisciplinaire de Physique (LIPhy) and the Laboratoire de Glaciologie et Géophysique de l'Environnement (LGGE) both in Grenoble (France), are discussed, covering atmospheric chemistry of high reactive species in polar regions and employing optical spectrometers for both in situ and laboratory measurements of glacial archives. In the framework of an ANR project, a transportable spectrometer based on the injection of a broadband frequency comb laser into a high-finesse optical cavity for the detection of IO, BrO, NO2 and H2CO has been realized.[1] The robust spectrometer provides shot-noise limited measurements for as long as 10 minutes, reaching detection limits of 0.04, 2, 10 and 200 ppt (2σ) for the four species, respectively. During the austral summer of 2011/12 the instrument has been used for monitoring, for the first time, NO2, IO and BrO at Dumont d'Urville Station at East of Antarctica. The measurements highlighted a different chemistry between East and West coast, with the halogen chemistry being promoted to the West and the OH and NOx chemistry on the East.[2] In the framework of a SUBGLACIOR project, an innovative drilling probe has been realized. The instrument is capable of retrieving in situ real-time vertical profiles of CH4 and δD of H2O trapped inside the ice sheet down to more than 3 km of depth within a single Antarctic season. The drilling probe containing an embedded OFCEAS (optical-feedback cavity-enhanced absorption spectroscopy) spectrometer will be extremely useful for (i) identify potential sites for investigating the oldest ice (aiming 1.5 Myrs BP records for resolving a major climate reorganization called the Mid-Pleistocene transition occurred around 1 Myrs ago) and (ii) providing direct access to past temperatures and climate cycles thanks to the vertical distribution of two key climatic signatures.[3] The spectrometer provides detection

  2. Measurement of natural radionuclides in phosphgypsum using an anti-cosmic gamma-ray spectrometer.

    PubMed

    Ferreux, Laurent; Moutard, Gérard; Branger, Thierry

    2009-05-01

    Gamma-ray spectrometry measurements have been carried out to determine the activity of natural radionuclides in a phosphogypsum sample included in a specific tight container. The gamma spectrometer includes an N-type coaxial high-purity germanium (HPGe) detector equipped with an anti-cosmic system. This measurement required the determination of linear attenuation coefficients of phosphogypsum to calculate self-absorption correction between efficiency calibration conditions and measurement ones. The results are given for the three natural chains and for (40)K, in term of specific activity/g of dry material, ranging from a few Bq kg(-1) to a few hundreds Bq kg(-1). The equilibrium within the different families and the (235)U/(238)U ratio are discussed.

  3. [Current status and prospects of portable NIR spectrometer].

    PubMed

    Yu, Xin-Yang; Lu, Qi-Peng; Gao, Hong-Zhi; Peng, Zhong-Qi

    2013-11-01

    Near-infrared spectroscopy (NIRS) is a reliable, rapid, and non-destructive analytical method widely applied in as a number of fields such as agriculture, food, chemical and oil industry. In order to suit different applications, near-infrared spectrometers are now varied. Portable near-infrared spectrometers are needed for rapid on-site identification and analysis. Instruments of this kind are rugged, compact and easy to be transported. In this paper, the current states of portable near-infrared spectrometers are reviewed. Portable near-infrared spectrometers are built of different monochromator systems: filter, grating, Fourier-transform methods, acousto-optic tunable filter (AOTF) and a large number of new methods based on micro-electro-mechanical systems (MEMS). The first part focuses on working principles of different monochromator systems. Advantages and disadvantages of different systems are also briefly mentioned. Descriptions of each method are given in turn. Typical spectrometers of each kind are introduced, and some parameters of these instruments are listed. In the next part we discuss sampling adapters, display, power supply and some other parts, which are designed to make the spectrometer more portable and easier to use. In the end, the current states of portable near-infrared spectrometers are summarized. Future trends of development of portable near-infrared spectrometers in China and abroad are discussed.

  4. ABSORPTION MEASURE DISTRIBUTION IN Mrk 509

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

    Adhikari, T. P.; Różańska, A.; Sobolewska, M.

    2015-12-20

    In this paper we model the observed absorption measure distribution (AMD) in Mrk 509, which spans three orders of magnitude in ionization level with a single-zone absorber in pressure equilibrium. AMD is usually constructed from observations of narrow absorption lines in radio-quiet active galaxies with warm absorbers. We study the properties of the warm absorber in Mrk 509 using recently published broadband spectral energy distribution observed with different instruments. This spectrum is an input in radiative transfer computations with full photoionization treatment using the titan code. We show that the simplest way to fully reproduce the shape of AMD is tomore » assume that the warm absorber is a single zone under constant total pressure. With this assumption, we found theoretical AMD that matches the observed AMD determined on the basis of the 600 ks reflection grating spectrometer XMM-Newton spectrum of Mrk 509. The softness of the source spectrum and the important role of the free–free emission breaks the usual degeneracy in the ionization state calculations, and the explicit dependence of the depths of AMD dips on density open a new path to the density diagnostic for the warm absorber. In Mrk 509, the implied density is of the order of 10{sup 8} cm{sup −3}.« less

  5. A new spatially scanning 2.7 µm laser hygrometer and new small-scale wind tunnel for direct analysis of the H2O boundary layer structure at single plant leaves

    NASA Astrophysics Data System (ADS)

    Wunderle, K.; Rascher, U.; Pieruschka, R.; Schurr, U.; Ebert, V.

    2015-01-01

    A new spatially scanning TDLAS in situ hygrometer based on a 2.7-µm DFB diode laser was constructed and used to analyse the water vapour concentration boundary layer structure at the surface of a single plant leaf. Using an absorption length of only 5.4 cm, the TDLAS hygrometer permits a H2O vapour concentration resolution of 31 ppmv. This corresponds to a normalized precision of 1.7 ppm m. In order to preserve and control the H2O boundary layer on an individual leaf and to study the boundary layer dependence on the wind speed to which the leaf might be exposed in nature, we also constructed a new, application specific, small-scale, wind tunnel for individual plant leaves. The rectangular, closed-loop tunnel has overall dimensions of 1.2 × 0.6 m and a measurement chamber dimension of 40 × 54 mm (H × W). It allows to generate a laminar flow with a precisely controlled wind speed at the plant leaf surface. Combining honeycombs and a miniaturized compression orifice, we could generate and control stable wind speeds from 0.1 to 0.9 m/s, and a highly laminar and homogeneous flow with an excellent relative spatial homogeneity of 0.969 ± 0.03. Combining the spectrometer and the wind tunnel, we analysed (for the first time) non-invasively the wind speed-dependent vertical structure of the H2O vapour distribution within the boundary layer of a single plant leaf. Using our time-lag-free data acquisition procedure for phase locked signal averaging, we achieved a temporal resolution of 0.2 s for an individual spatial point, while a complete vertical spatial scan at a spatial resolution of 0.18 mm took 77 s. The boundary layer thickness was found to decrease from 6.7 to 3.6 mm at increasing wind speeds of 0.1-0.9 m/s. According to our knowledge, this is the first experimental quantification of wind speed-dependent H2O vapour boundary layer concentration profiles of single plant leaves.

  6. Assessment of Transition Element Speciation in Glasses Using a Portable Transmission Ultraviolet-Visible-Near-Infrared (UV-Vis-NIR) Spectrometer.

    PubMed

    Hunault, Myrtille; Lelong, Gérald; Gauthier, Michel; Gélébart, Frédéric; Ismael, Saindou; Galoisy, Laurence; Bauchau, Fanny; Loisel, Claudine; Calas, Georges

    2016-05-01

    A new low-cost experimental setup based on two compact dispersive optical spectrometers has been developed to measure optical absorption transmission spectra over the 350-2500 nm energy range. We demonstrate how near-infrared (NIR) data are essential to identify the coloring species in addition to ultraviolet visible data. After calibration with reference glasses, the use of an original sample stage that maintains the window panel in the vertical position enables the comparison of ancient and modern glasses embedded in a panel from the Sainte-Chapelle of Paris, without any sampling. The spectral resolution enables to observe fine resonances arising in the absorption bands of Cr(3+), and the complementary information obtained in the NIR enables to determine the contribution of Fe(2+), a key indicator of glassmaking conditions. © The Author(s) 2016.

  7. General study of asymmetrical crossed Czerny-Turner spectrometer.

    PubMed

    Tang, Ming; Fan, Xianguang; Wang, Xin; Xu, Yingjie; Que, Jing; He, Jian

    2015-11-20

    A study of the spectrum resolution, wavelength range, and primary aberration of the asymmetrical crossed Czerny-Turner spectrometer is presented by deducing the relationship between them and structural parameters of the spectrometer in a new way of thinking based on simple but effective geometric models. The analysis was verified in an experiment and simulation performed on the optical design program ZEMAX, and the obtained results agree with the analysis. Owing to the analysis, initial designed parameters of the spectrometer were given and then optimized by ZEMAX; with the instruction of the study, a small adjustment was made in the actual alignment to obtain the desired final spectrometer. The spectrometer successfully measured the last four characteristic peaks of the Raman spectrum of CCL4, which demonstrates that the research provides important guidance to the design and alignment of an asymmetrical crossed Czerny-Turner spectrometer.

  8. Multi-spectrometer calibration transfer based on independent component analysis.

    PubMed

    Liu, Yan; Xu, Hao; Xia, Zhenzhen; Gong, Zhiyong

    2018-02-26

    Calibration transfer is indispensable for practical applications of near infrared (NIR) spectroscopy due to the need for precise and consistent measurements across different spectrometers. In this work, a method for multi-spectrometer calibration transfer is described based on independent component analysis (ICA). A spectral matrix is first obtained by aligning the spectra measured on different spectrometers. Then, by using independent component analysis, the aligned spectral matrix is decomposed into the mixing matrix and the independent components of different spectrometers. These differing measurements between spectrometers can then be standardized by correcting the coefficients within the independent components. Two NIR datasets of corn and edible oil samples measured with three and four spectrometers, respectively, were used to test the reliability of this method. The results of both datasets reveal that spectra measurements across different spectrometers can be transferred simultaneously and that the partial least squares (PLS) models built with the measurements on one spectrometer can predict that the spectra can be transferred correctly on another.

  9. Dipole saturated absorption modeling in gas phase: Dealing with a Gaussian beam

    NASA Astrophysics Data System (ADS)

    Dupré, Patrick

    2018-01-01

    With the advent of new accurate and sensitive spectrometers, cf. combining optical cavities (for absorption enhancement), the requirement for reliable molecular transition modeling is becoming more pressing. Unfortunately, there is no trivial approach which can provide a definitive formalism allowing us to solve the coupled systems of equations associated with nonlinear absorption. Here, we propose a general approach to deal with any spectral shape of the electromagnetic field interacting with a molecular species under saturation conditions. The development is specifically applied to Gaussian-shaped beams. To make the analytical expressions tractable, approximations are proposed. Finally, two or three numerical integrations are required for describing the Lamb-dip profile. The implemented model allows us to describe the saturated absorption under low pressure conditions where the broadening by the transit-time may dominate the collision rates. The model is applied to two specific overtone transitions of the molecular acetylene. The simulated line shapes are discussed versus the collision and the transit-time rates. The specific collisional and collision-free regimes are illustrated, while the Rabi frequency controls the intermediate regime. We illustrate how to recover the input parameters by fitting the simulated profiles.

  10. [Design of Dual-Beam Spectrometer in Spectrophotometer for Colorimetry].

    PubMed

    Liu, Yi-xuan; Yan, Chang-xiang

    2015-07-01

    Spectrophotometers for colorimetry are usually composed of two independent and identical spectrometers. In order to reduce the volume of spectrophotometer for colorimetry, a design method of double-beam spectrometer is put forward. A traditional spectrometer is modified so that a new spectrometer can realize the function of double spectrometers, which is especially suitable for portable instruments. One slit is replaced by the double-slit, than two beams of spectrum can be detected. The working principle and design requirement of double-beam spectrometer are described. A spectrometer of portable spectrophotometer is designed by this method. A toroidal imaging mirror is used for the Czerny-Turner double-beam spectrometer in this paper, which can better correct astigmatism, and prevent the dual-beam spectral crosstalk. The results demonstrate that the double-beam spectrometer designed by this method meets the design specifications, with the spectral resolution less than 10 nm, the spectral length of 9.12 mm, and the volume of 57 mm x 54 mm x 23 mm, and without the dual-beam spectral overlap in the detector either. Comparing with a traditional spectrophotometer, the modified spectrophotometer uses a set of double-beam spectrometer instead of two sets of spectrometers, which can greatly reduce the volume. This design method can be specially applied in portable spectrophotometers, also can be widely applied in other double-beam spectrophotometers, which offers a new idea for the design of dual-beam spectrophotometers.

  11. New in situ Aerosol Spectral Optical Measurements over 300-700 nm, Extinction and Total Absorption, Paired with Absorption from Water- and Methanol-soluble Aerosol Extracts

    NASA Astrophysics Data System (ADS)

    Jordan, C. E.; Stauffer, R. M.; Lamb, B.; Novak, M. G.; Mannino, A.; Hudgins, C.; Thornhill, K. L., II; Crosbie, E.; Winstead, E.; Anderson, B.; Martin, R.; Shook, M.; Ziemba, L. D.; Beyersdorf, A. J.; Corr, C.

    2017-12-01

    A new in situ spectral aerosol extinction instrument (custom built, SpEx) built to cover the 300-700 nm range at 1 nm spectral resolution and temporal resolution of 4 minutes was deployed on the top deck ( 10 m above the water surface) of the R/V Onnuri during the KORUS-OC research cruise around South Korea in spring 2016. This new instrument was one component of a suite of in situ aerosol optical measurements that included 3-visible-wavelength scattering (Airphoton IN101 Nephelometer, at 450, 532, & 632 nm) and absorption (Brechtel Tricolor Absorption Photometer Model 2901, at 467, 528, & 652 nm) with sub-minute temporal resolution; two sets of filters (Teflon and glass fiber, both collected over 3 hour daytime and 12 hour overnight intervals) to provide aerosol absorption spectra over the same wavelength range as SpEx. The glass fiber filters were placed in the center of an integrating sphere (Labsphere DRA-CA-30) attached to a dual beam spectrophotometer (Cary 100 Bio UV-Visible Spectrophotometer) to measure total aerosol absorption spectra via an established method used by the ocean color community to obtain absorption spectra from particles suspended in sea water. Adapting this methodology for atmospheric aerosol measurements provides a new avenue to obtain spectral total aerosol absorption, particularly useful for expanding in situ measurement capabilities into the UV range. The Teflon filters were cut in half with one half extracted in deionized water and the other half extracted in methanol. The solutions were filtered and injected into a liquid waveguide capillary cell (World Precision Instruments LWCC-3100, 100 cm pathlength) to measure the absorption spectra for each solution. In addition, the water extracts were measured via ion chromatography (Dionex ICS-3000 Ion Chromatography System) to obtain water-soluble inorganic ion concentrations, as well as via aerosol mass spectrometry (Aerodyne Research, Inc. HR-ToF High Resolution Aerosol Mass Spectrometer

  12. Compact reflective imaging spectrometer utilizing immersed gratings

    DOEpatents

    Chrisp, Michael P [Danville, CA

    2006-05-09

    A compact imaging spectrometer comprising an entrance slit for directing light, a first mirror that receives said light and reflects said light, an immersive diffraction grating that diffracts said light, a second mirror that focuses said light, and a detector array that receives said focused light. The compact imaging spectrometer can be utilized for remote sensing imaging spectrometers where size and weight are of primary importance.

  13. How to Design a Spectrometer.

    PubMed

    Scheeline, Alexander

    2017-10-01

    Designing a spectrometer requires knowledge of the problem to be solved, the molecules whose properties will contribute to a solution of that problem and skill in many subfields of science and engineering. A seemingly simple problem, design of an ultraviolet, visible, and near-infrared spectrometer, is used to show the reasoning behind the trade-offs in instrument design. Rather than reporting a fully optimized instrument, the Yin and Yang of design choices, leading to decisions about financial cost, materials choice, resolution, throughput, aperture, and layout are described. To limit scope, aspects such as grating blaze, electronics design, and light sources are not presented. The review illustrates the mixture of mathematical rigor, rule of thumb, esthetics, and availability of components that contribute to the art of spectrometer design.

  14. Airborne spectroradiometry: The application of AIS data to detecting subtle mineral absorption features

    NASA Technical Reports Server (NTRS)

    Cocks, T. D.; Green, A. A.

    1986-01-01

    Analysis of Airborne Imaging Spectrometer (AIS) data acquired in Australia has revealed a number of operational problems. Horizontal striping in AIS imagery and spectral distortions due to order overlap were investigated. Horizontal striping, caused by grating position errors can be removed with little or no effect on spectral details. Order overlap remains a problem that seriously compromises identification of subtle mineral absorption features within AIS spectra. A spectrometric model of the AIS was developed to assist in identifying spurious spectral features, and will be used in efforts to restore the spectral integrity of the data.

  15. The Apollo Alpha Spectrometer.

    NASA Technical Reports Server (NTRS)

    Jagoda, N.; Kubierschky, K.; Frank, R.; Carroll, J.

    1973-01-01

    Located in the Science Instrument Module of Apollo 15 and 16, the Alpha Particle Spectrometer was designed to detect and measure the energy of alpha particles emitted by the radon isotopes and their daughter products. The spectrometer sensor consisted of an array of totally depleted silicon surface barrier detectors. Biased amplifier and linear gate techniques were utilized to reduce resolution degradation, thereby permitting the use of a single 512 channel PHA. Sensor identification and in-flight radioactive calibration were incorporated to enhance data reduction.

  16. Determination of UV-visible-NIR absorption coefficient of graphite bulk using direct and indirect methods

    NASA Astrophysics Data System (ADS)

    Smausz, T.; Kondász, B.; Gera, T.; Ajtai, T.; Utry, N.; Pintér, M.; Kiss-Albert, G.; Budai, J.; Bozóki, Z.; Szabó, G.; Hopp, B.

    2017-10-01

    Absorption coefficient of graphite bulk pressed from 1 to 5 μm-sized crystalline grains was measured in UV-Vis-NIR range with three different methods: (i) determination of pulsed laser ablation rate as the function of laser fluence for different wavelengths (248, 337, 532, and 1064 nm, respectively); (ii) production of aerosol particles by UV laser ablation of the bulk graphite in inert atmosphere and determination of the mass-specific absorption coefficient with a four-wavelength (266, 355, 532, and 1064 nm, respectively) photoacoustic spectrometer, and (iii) spectroscopic ellipsometry in 250-1000 nm range. Taking into account the wide range of the absorption coefficients of different carbon structures, an overall relatively good agreement was observed for the three methods. The ellipsometric results fit well with the ablation rate measurement, and the data obtained with photoacoustic method are also similar in the UV and NIR region; however, the values were somewhat higher in visible and near-UV range. Taking into account the limitations of the methods, they can be promising candidates for the determination of absorption coefficient when the samples are strongly scattering and there is no possibility to perform transmissivity measurements.

  17. Superconducting High Resolution Fast-Neutron Spectrometers

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

    Hau, Ionel Dragos

    2006-01-01

    Superconducting high resolution fast-neutron calorimetric spectrometers based on 6LiF and TiB{sub 2} absorbers have been developed. These novel cryogenic spectrometers measure the temperature rise produced in exothermal (n, α) reactions with fast neutrons in 6Li and 10B-loaded materials with heat capacity C operating at temperatures T close to 0.1 K. Temperature variations on the order of 0.5 mK are measured with a Mo/Cu thin film multilayer operated in the transition region between its superconducting and its normal state. The advantage of calorimetry for high resolution spectroscopy is due to the small phonon excitation energies k BT on the order ofmore » μeV that serve as signal carriers, resulting in an energy resolution ΔE ~ (k BT 2C) 1/2, which can be well below 10 keV. An energy resolution of 5.5 keV has been obtained with a Mo/Cu superconducting sensor and a TiB 2 absorber using thermal neutrons from a 252Cf neutron source. This resolution is sufficient to observe the effect of recoil nuclei broadening in neutron spectra, which has been related to the lifetime of the first excited state in 7Li. Fast-neutron spectra obtained with a 6Li-enriched LiF absorber show an energy resolution of 16 keV FWHM, and a response in agreement with the 6Li(n, α) 3H reaction cross section and Monte Carlo simulations for energies up to several MeV. The energy resolution of order of a few keV makes this novel instrument applicable to fast-neutron transmission spectroscopy based on the unique elemental signature provided by the neutron absorption and scattering resonances. The optimization of the energy resolution based on analytical and numerical models of the detector response is discussed in the context of these applications.« less

  18. Aerosol Angstrom Absorption Coefficient Comparisons during MILAGRO.

    NASA Astrophysics Data System (ADS)

    Marley, N. A.; Marchany-Rivera, A.; Kelley, K. L.; Mangu, A.; Gaffney, J. S.

    2007-12-01

    Measurements of aerosol absorption were obtained as part of the MAX-Mex component of the MILAGRO field campaign at site T0 (Instituto Mexicano de Petroleo in Mexico City) by using a 7-channel aethalometer (Thermo- Anderson) during the month of March, 2006. The absorption measurements obtained in the field at 370, 470, 520, 590, 660, 880, and 950 nm were used to determine the aerosol Angstrom absorption exponents by linear regression. Since, unlike other absorbing aerosol species (e.g. humic like substances, nitrated PAHs), black carbon absorption is relatively constant from the ultraviolet to the infrared with an Angstrom absorption exponent of -1 (1), a comparison of the Angstrom exponents can indicate the presence of aerosol components with an enhanced UV absorption over that expected from BC content alone. The Angstrom exponents determined from the aerosol absorption measurements obtained in the field varied from - 0.7 to - 1.3 during the study and was generally lower in the afternoon than the morning hours, indicating an increase in secondary aerosol formation and photochemically generated UV absorbing species in the afternoon. Twelve-hour integrated samples of fine atmospheric aerosols (<0.1micron) were also collected at site T0 and T1 (Universidad Technologica de Tecamac, State of Mexico) from 5 am to 5 pm (day) and from 5 pm to 5 am (night) during the month of March 2006. Samples were collected on quartz fiber filters with high volume impactor samplers. Continuous absorption spectra of these aerosol samples have been obtained in the laboratory from 280 to 900nm with the use of an integrating sphere coupled to a UV spectrometer (Beckman DU with a Labsphere accessory). The integrating sphere allows the detector to collect and spatially integrate the total radiant flux reflected from the sample and therefore allows for the measurement of absorption on highly reflective or diffusely scattering samples. These continuous spectra have also been used to obtain the

  19. Handheld spectrometers: the state of the art

    NASA Astrophysics Data System (ADS)

    Crocombe, Richard A.

    2013-05-01

    "Small" spectrometers fall into three broad classes: small versions of laboratory instruments, providing data, subsequently processed on a PC; dedicated analyzers, providing actionable information to an individual operator; and process analyzers, providing quantitative or semi-quantitative information to a process controller. The emphasis of this paper is on handheld dedicated analyzers. Many spectrometers have historically been large, possible fragile, expensive and complicated to use. The challenge over the last dozen years, as instruments have moved into the field, has been to make spectrometers smaller, affordable, rugged, easy-to-use, but most of all capable of delivering actionable results. Actionable results can dramatically improve the efficiency of a testing process and transform the way business is done. There are several keys to this handheld spectrometer revolution. Consumer electronics has given us powerful mobile platforms, compact batteries, clearly visible displays, new user interfaces, etc., while telecomm has revolutionized miniature optics, sources and detectors. While these technologies enable miniature spectrometers themselves, actionable information has demanded the development of rugged algorithms for material confirmation, unknown identification, mixture analysis and detection of suspicious materials in unknown matrices. These algorithms are far more sophisticated than the `correlation' or `dot-product' methods commonly used in benchtop instruments. Finally, continuing consumer electronics advances now enable many more technologies to be incorporated into handheld spectrometers, including Bluetooth, wireless, WiFi, GPS, cameras and bar code readers, and the continued size shrinkage of spectrometer `engines' leads to the prospect of dual technology or `hyphenated' handheld instruments.

  20. Miniature Raman spectrometer development

    NASA Astrophysics Data System (ADS)

    Bonvallet, Joseph; Auz, Bryan; Rodriguez, John; Olmstead, Ty

    2018-02-01

    The development of techniques to rapidly identify samples ranging from, molecule and particle imaging to detection of high explosive materials, has surged in recent years. Due to this growing want, Raman spectroscopy gives a molecular fingerprint, with no sample preparation, and can be done remotely. These systems can be small, compact, lightweight, and with a user interface that allows for easy use and sample identification. Ocean Optics Inc. has developed several systems that would meet all these end user requirements. This talk will describe the development of different Ocean Optics Inc miniature Raman spectrometers. The spectrometer on a phone (SOAP) system was designed using commercial off the shelf (COTS) components, in a rapid product development cycle. The footprint of the system measures 40x40x14 mm (LxWxH) and was coupled directly to the cell phone detector camera optics. However, it gets roughly only 40 cm-1 resolution. The Accuman system is the largest (290x220X100 mm) of the three, but uses our QEPro spectrometer and get 7-11 cm-1 resolution. Finally, the HRS-30 measuring 165x85x40 mm is a combination of the other two systems. This system uses a modified EMBED spectrometer and gets 7-12 cm-1 resolution. Each of these units uses a peak matching algorithm that then correlates the results to the pre-loaded and customizable spectral libraries.

  1. ICL-based TDLAS sensor for real-time breath gas analysis of carbon monoxide isotopes.

    PubMed

    Ghorbani, Ramin; Schmidt, Florian M

    2017-05-29

    We present a compact sensor for carbon monoxide (CO) in air and exhaled breath based on a room temperature interband cascade laser (ICL) operating at 4.69 µm, a low-volume circular multipass cell and wavelength modulation absorption spectroscopy. A fringe-limited (1σ) sensitivity of 6.5 × 10 -8 cm -1 Hz -1/2 and a detection limit of 9 ± 5 ppbv at 0.07 s acquisition time are achieved, which constitutes a 25-fold improvement compared to direct absorption spectroscopy. Integration over 10 s increases the precision to 0.6 ppbv. The setup also allows measuring the stable isotope 13 CO in breath. We demonstrate quantification of indoor air CO and real-time detection of CO expirograms from healthy non-smokers and a healthy smoker before and after smoking. Isotope ratio analysis indicates depletion of 13 CO in breath compared to natural abundance.

  2. Ultraviolet spectrometer experiment for the Voyager mission

    NASA Technical Reports Server (NTRS)

    Broadfoot, A. L.; Sandel, B. R.; Shemansky, D. E.; Atreya, S. K.; Donahue, T. M.; Moos, H. W.; Bertaux, J. L.; Blamont, J. E.; Ajello, J. M.; Strobel, D. F.

    1977-01-01

    An objective grating spectrometer covering the wavelength range of 500 to 1700 A with a 10-A resolution is employed for the Voyager ultraviolet spectrometer experiment. In determining the composition and structure of the atmospheres of Saturn, Jupiter and several satellites, the ultraviolet spectrometer will rely on airglow mode observations to measure radiation from the atmospheres due to resonant scattering of solar flux, and the occultation mode for assessments of the atmospheric extinction of solar or stellar radiation as the spacecraft enters shadow zones. Since it is capable of prolonged stellar observations in the 500 to 1000 A wavelength range, the spectrometer is expected to make important contributions to exploratory studies of UV sources.

  3. Towards absolute laser spectroscopic CO2 isotope ratio measurements

    NASA Astrophysics Data System (ADS)

    Anyangwe Nwaboh, Javis; Werhahn, Olav; Ebert, Volker

    2017-04-01

    Knowledge of isotope composition of carbon dioxide (CO2) in the atmosphere is necessary to identify sources and sinks of this key greenhouse gas. In the last years, laser spectroscopic techniques such as cavity ring-down spectroscopy (CRDS) and tunable diode laser absorption spectroscopy (TDLAS) have been shown to perform accurate isotope ratio measurements for CO2 and other gases like water vapour (H2O) [1,2]. Typically, isotope ratios are reported in literature referring to reference materials provided by e.g. the International Atomic Energy Agency (IAEA). However, there could be some benefit if field deployable absolute isotope ratio measurement methods were developed to address issues such as exhausted reference material like the Pee Dee Belemnite (PDB) standard. Absolute isotope ratio measurements would be particularly important for situations where reference materials do not even exist. Here, we present CRDS and TDLAS-based absolute isotope ratios (13C/12C ) in atmospheric CO2. We demonstrate the capabilities of the used methods by measuring CO2 isotope ratios in gas standards. We compare our results to values reported for the isotope certified gas standards. Guide to the expression of uncertainty in measurement (GUM) compliant uncertainty budgets on the CRDS and TDLAS absolute isotope ratio measurements are presented, and traceability is addressed. We outline the current impediments in realizing high accuracy absolute isotope ratio measurements using laser spectroscopic methods, propose solutions and the way forward. Acknowledgement Parts of this work have been carried out within the European Metrology Research Programme (EMRP) ENV52 project-HIGHGAS. The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union. References [1] B. Kühnreich, S. Wagner, J. C. Habig,·O. Möhler, H. Saathoff, V. Ebert, Appl. Phys. B 119:177-187 (2015). [2] E. Kerstel, L. Gianfrani, Appl. Phys. B 92, 439-449 (2008).

  4. Aerosol retrieval for APEX airborne imaging spectrometer: a preliminary analysis

    NASA Astrophysics Data System (ADS)

    Seidel, Felix; Nieke, Jens; Schläpfer, Daniel; Höller, Robert; von Hoyningen-Huene, Wolfgang; Itten, Klaus

    2005-10-01

    In order to achieve quantitative measurements of the Earth's surface radiance and reflectance, it is important to determine the aerosol optical thickness (AOT) to correct for the optical influence of atmospheric particles. An advanced method for aerosol detection and quantification is required, which is not strongly dependant on disturbing effects due to surface reflectance, gas absorption and Rayleigh scattering features. A short review of existing applicable methods to the APEX airborne imaging spectrometer (380nm to 2500nm), leads to the suggested aerosol retrieval method here in this paper. It will measure the distinct radiance change between two near-UV spectral bands (385nm & 412nm) due to aerosol induced scattering and absorption features. Atmospheric radiation transfer model calculations have been used to analyze the AOT retrieval capability and accuracy of APEX. The noise-equivalent differential AOT is presented along with the retrieval sensitivity to various input variables. It is shown, that the suggested method will be able to identify different aerosol model types and measure AOT and columnar size distribution. The proposed accurate AOT determination will lead to a unique opportunity of two-dimensional pixel-wise mapping of aerosol properties at a high spatial resolution. This will be helpful especially for regional climate studies, atmospheric pollution monitoring and for the improvement of aerosol dispersion models and the validation of aerosol algorithms on spaceborne sensors.

  5. Landsat-Swath Imaging Spectrometer Design

    NASA Technical Reports Server (NTRS)

    Mouroulis, Pantazis; Green, Robert O.; Van Gorp, Byron; Moore, Lori; Wilson, Daniel W.; Bender, Holly A.

    2015-01-01

    We describe the design of a high-throughput pushbroom imaging spectrometer and telescope system that is capable of Landsat swath and resolution while providing better than 10 nm per pixel spectral resolution. The design is based on a 3200 x 480 element x 18 µm pixel size focal plane array, two of which are utilized to cover the full swath. At an optical speed of F/1.8, the system is the fastest proposed to date to our knowledge. The utilization of only two spectrometer modules fed from the same telescope reduces system complexity while providing a solution within achievable detector technology. Predictions of complete system response are shown. Also, it is shown that detailed ghost analysis is a requirement for this type of spectrometer and forms an essential part of a complete design.

  6. Imaging spectrometer using a liquid crystal tunable filter

    NASA Astrophysics Data System (ADS)

    Chrien, Thomas G.; Chovit, Christopher; Miller, Peter J.

    1993-09-01

    A demonstration imaging spectrometer using a liquid crystal tunable filter (LCTF) was built and tested on a hot air balloon platform. The LCTF is a tunable polarization interference or Lyot filter. The LCTF enables a small, light weight, low power, band sequential imaging spectrometer design. An overview of the prototype system is given along with a description of balloon experiment results. System model performance predictions are given for a future LCTF based imaging spectrometer design. System design considerations of LCTF imaging spectrometers are discussed.

  7. Middle infrared optoelectronic absorption systems for monitoring physiological glucose solutions

    NASA Astrophysics Data System (ADS)

    Martin, W. Blake

    Tight monitoring of the glucose levels for diabetic individuals is essential to control long-term complications. A definitive diabetes management system has yet to be developed for the diabetic. This research investigates the application of middle infrared absorption frequencies for monitoring glucose levels in biological solutions. Three frequencies were identified using a Fourier transform infrared spectrometer and correlated to changes in glucose concentrations. The 1035 +/- 1 cm-1 frequency was determined to be the best representative frequency. Other biological molecules contributed no significant interference to monitoring glucose absorption. A second frequency at 1193 cm-1 was suggested as a representative background absorption frequency, which could be used for more accurate glucose absorption values. Next, a quantum cascade laser optoelectronic absorption system was designed and developed to monitor glucose. After careful alignment and design, the system was used to monitor physiological glucose concentrations. Correlation at 1036 cm-1 with glucose changes was comparable to the previous results. The use of the background absorption frequency was verified. This frequency essentially acts as a calibrating frequency to adjust in real-time to any changes in the background absorption that may alter the accuracy of the predicted glucose value. An evanescent wave cavity ring-down spectroscopy technique was explored to monitor molecules in a biological solution. Visible light at 425 nm was used to monitor hemoglobin in control urine samples. An adsorption isotherm for hemoglobin was detectable to limit of 5.8 nM. Evanescent wave cavity ring-down spectroscopy would be useful for a glucose solution. Given an equivalent system designed for the middle infrared, the molar extinction coefficient of glucose allows for a detectable limit of 45 mg/dl for a free-floating glucose solution, which is below normal physiological concentrations. The future use of a hydrophobic

  8. Ion mass spectrometer

    NASA Technical Reports Server (NTRS)

    Neugebauer, M. (Inventor); Clay, D. R.; Goldstein, B. E.; Goldstein, R.

    1984-01-01

    An ion mass spectrometer is described which detects and indicates the characteristics of ions received over a wide angle, and which indicates the mass to charge ratio, the energy, and the direction of each detected ion. The spectrometer includes a magnetic analyzer having a sector magnet that passes ions received over a wide angle, and an electrostatic analyzer positioned to receive ions passing through the magnetic analyzer. The electrostatic analyzer includes a two dimensional ion sensor at one wall of the analyzer chamber, that senses not only the lengthwise position of the detected ion to indicate its mass to charge ratio, but also detects the ion position along the width of the chamber to indicate the direction in which the ion was traveling.

  9. FAST NEUTRON SPECTROMETER

    DOEpatents

    Davis, F.J.; Hurst, G.S.; Reinhardt, P.W.

    1959-08-18

    An improved proton recoil spectrometer for determining the energy spectrum of a fast neutron beam is described. Instead of discriminating against and thereby"throwing away" the many recoil protons other than those traveling parallel to the neutron beam axis as do conventional spectrometers, this device utilizes protons scattered over a very wide solid angle. An ovoidal gas-filled recoil chamber is coated on the inside with a scintillator. The ovoidal shape of the sensitive portion of the wall defining the chamber conforms to the envelope of the range of the proton recoils from the radiator disposed within the chamber. A photomultiplier monitors the output of the scintillator, and a counter counts the pulses caused by protons of energy just sufficient to reach the scintillator.

  10. Absorption spectrum of the firefly luciferin anion isolated in vacuo.

    PubMed

    Støchkel, Kristian; Milne, Bruce F; Brøndsted Nielsen, Steen

    2011-03-24

    The excited-state physics of the firefly luciferin anion depends on its chemical environment, and it is therefore important to establish the intrinsic behavior of the bare ion. Here we report electronic absorption spectra of the anion isolated in vacuo obtained at an electrostatic ion storage ring and an accelerator mass spectrometer where ionic dissociation is monitored on a long time scale (from 33 μs and up to 3 ms) and on a short time scale (0-3 μs), respectively. In the ring experiment the yield of all neutrals (mainly CO(2)) as a function of wavelength was measured whereas in the single pass experiment, the abundance of daughter ions formed after loss of CO(2) was recorded to provide action spectra. We find maxima at 535 and 265 nm, and that the band shape is largely determined by the sampling time interval, which is due to the kinetics of the dissociation process. Calculations at the TD-B3LYP/TZVPP++ level predict maximum absorption at 533 and 275 nm for the carboxylate isomer in excellent agreement with the experimental findings. The phenolate isomer lies higher in energy by 0.22 eV, and also its absorption maximum is calculated to be at 463 nm, which is far away from the experimental value. Our data serve to benchmark future theoretical models for bioluminescence from fireflies.

  11. Relative importance of black carbon, brown carbon, and absorption enhancement from clear coatings in biomass burning emissions

    NASA Astrophysics Data System (ADS)

    Pokhrel, Rudra P.; Beamesderfer, Eric R.; Wagner, Nick L.; Langridge, Justin M.; Lack, Daniel A.; Jayarathne, Thilina; Stone, Elizabeth A.; Stockwell, Chelsea E.; Yokelson, Robert J.; Murphy, Shane M.

    2017-04-01

    A wide range of globally significant biomass fuels were burned during the fourth Fire Lab at Missoula Experiment (FLAME-4). A multi-channel photoacoustic absorption spectrometer (PAS) measured dry absorption at 405, 532, and 660 nm and thermally denuded (250 °C) absorption at 405 and 660 nm. Absorption coefficients were broken into contributions from black carbon (BC), brown carbon (BrC), and lensing following three different methodologies, with one extreme being a method that assumes the thermal denuder effectively removes organics and the other extreme being a method based on the assumption that black carbon (BC) has an Ångström exponent of unity. The methodologies employed provide ranges of potential importance of BrC to absorption but, on average, there was a difference of a factor of 2 in the ratio of the fraction of absorption attributable to BrC estimated by the two methods. BrC absorption at shorter visible wavelengths is of equal or greater importance to that of BC, with maximum contributions of up to 92 % of total aerosol absorption at 405 nm and up to 58 % of total absorption at 532 nm. Lensing is estimated to contribute a maximum of 30 % of total absorption, but typically contributes much less than this. Absorption enhancements and the estimated fraction of absorption from BrC show good correlation with the elemental-carbon-to-organic-carbon ratio (EC / OC) of emitted aerosols and weaker correlation with the modified combustion efficiency (MCE). Previous studies have shown that BrC grows darker (larger imaginary refractive index) as the ratio of black to organic aerosol (OA) mass increases. This study is consistent with those findings but also demonstrates that the fraction of total absorption attributable to BrC shows the opposite trend: increasing as the organic fraction of aerosol emissions increases and the EC / OC ratio decreases.

  12. Substitution effects on the absorption spectra of nitrophenolate isomers.

    PubMed

    Wanko, Marius; Houmøller, Jørgen; Støchkel, Kristian; Suhr Kirketerp, Maj-Britt; Petersen, Michael Åxman; Nielsen, Mogens Brøndsted; Nielsen, Steen Brøndsted; Rubio, Angel

    2012-10-05

    Charge-transfer excitations highly depend on the electronic coupling between the donor and acceptor groups. Nitrophenolates are simple examples of charge-transfer systems where the degree of coupling differs between ortho, meta and para isomers. Here we report the absorption spectra of the isolated anions in vacuo to avoid the complications of solvent effects. Gas-phase action spectroscopy was done with two different setups, an electrostatic ion storage ring and an accelerator mass spectrometer. The results are interpreted on the basis of CC2 quantum chemical calculations. We identified absorption maxima at 393, 532, and 399 nm for the para, meta, and ortho isomer, respectively, with the charge-transfer transition into the lowest excited singlet state. In the meta isomer, this π-π* transition is strongly redshifted and its oscillator strength reduced, which is related to the pronounced charge-transfer character, as a consequence of the topology of the conjugated π-system. Each isomer's different charge distribution in the ground state leads to a very different solvent shift, which in acetonitrile is bathochromic for the para and ortho, but hypsochromic for the meta isomer.

  13. Composite Spectrometer Prisms

    NASA Technical Reports Server (NTRS)

    Breckinridge, J. B.; Page, N. A.; Rodgers, J. M.

    1985-01-01

    Efficient linear dispersive element for spectrometer instruments achieved using several different glasses in multiple-element prism. Good results obtained in both two-and three-element prisms using variety of different glass materials.

  14. Spectrometer gun

    DOEpatents

    Waechter, David A.; Wolf, Michael A.; Umbarger, C. John

    1985-01-01

    A hand-holdable, battery-operated, microprocessor-based spectrometer gun includes a low-power matrix display and sufficient memory to permit both real-time observation and extended analysis of detected radiation pulses. Universality of the incorporated signal processing circuitry permits operation with various detectors having differing pulse detection and sensitivity parameters.

  15. Thermal stabilization of static single-mirror Fourier transform spectrometers

    NASA Astrophysics Data System (ADS)

    Schardt, Michael; Schwaller, Christian; Tremmel, Anton J.; Koch, Alexander W.

    2017-05-01

    Fourier transform spectroscopy has become a standard method for spectral analysis of infrared light. With this method, an interferogram is created by two beam interference which is subsequently Fourier-transformed. Most Fourier transform spectrometers used today provide the interferogram in the temporal domain. In contrast, static Fourier transform spectrometers generate interferograms in the spatial domain. One example of this type of spectrometer is the static single-mirror Fourier transform spectrometer which offers a high etendue in combination with a simple, miniaturized optics design. As no moving parts are required, it also features a high vibration resistance and high measurement rates. However, it is susceptible to temperature variations. In this paper, we therefore discuss the main sources for temperature-induced errors in static single-mirror Fourier transform spectrometers: changes in the refractive index of the optical components used, variations of the detector sensitivity, and thermal expansion of the housing. As these errors manifest themselves in temperature-dependent wavenumber shifts and intensity shifts, they prevent static single-mirror Fourier transform spectrometers from delivering long-term stable spectra. To eliminate these shifts, we additionally present a work concept for the thermal stabilization of the spectrometer. With this stabilization, static single-mirror Fourier transform spectrometers are made suitable for infrared process spectroscopy under harsh thermal environmental conditions. As the static single-mirror Fourier transform spectrometer uses the so-called source-doubling principle, many of the mentioned findings are transferable to other designs of static Fourier transform spectrometers based on the same principle.

  16. Mass Spectrometers in Space!

    NASA Technical Reports Server (NTRS)

    Brinckerhoff, William B.

    2012-01-01

    Exploration of our solar system over several decades has benefitted greatly from the sensitive chemical analyses offered by spaceflight mass spectrometers. When dealing with an unknown environment, the broadband detection capabilities of mass analyzers have proven extremely valuable in determining the composition and thereby the basic nature of space environments, including the outer reaches of Earth s atmosphere, interplanetary space, the Moon, and the planets and their satellites. Numerous mass analyzer types, including quadrupole, monopole, sector, ion trap, and time-of-flight have been incorporated in flight instruments and delivered robotically to a variety of planetary environments. All such instruments went through a rigorous process of application-specific development, often including significant miniaturization, testing, and qualification for the space environment. Upcoming missions to Mars and opportunities for missions to Venus, Europa, Saturn, Titan, asteroids, and comets provide new challenges for flight mass spectrometers that push to state of the art in fundamental analytical technique. The Sample Analysis at Mars (SAM) investigation on the recently-launch Mars Science Laboratory (MSL) rover mission incorporates a quadrupole analyzer to support direct evolved gas as well as gas chromatograph-based analysis of martian rocks and atmosphere, seeking signs of a past or present habitable environment. A next-generation linear ion trap mass spectrometer, using both electron impact and laser ionization, is being incorporated into the Mars Organic Molecule Analyzer (MOMA) instrument, which will be flown to Mars in 2018. These and other mass spectrometers and mission concepts at various stages of development will be described.

  17. Spacecraft Applications of Compact Optical and Mass Spectrometers

    NASA Technical Reports Server (NTRS)

    Davinic, N. M.; Nagel, D. J.

    1995-01-01

    Optical spectrometers, and mass spectrometers to a lesser extent, have a long and rich history of use aboard spacecraft. Space mission applications include deep space science spacecraft, earth orbiting satellites, atmospheric probes, and surface landers, rovers, and penetrators. The large size of capable instruments limited their use to large, expensive spacecraft. Because of the novel application of micro-fabrication technologies, compact optical and mass spectrometers are now available. The new compact devices are especially attractive for spacecraft because of their small mass and volume, as well as their low power consumption. Dispersive optical multi-channel analyzers which cover the 0.4-1.1 micrometer wavelength are now commercially available in packages as small as 3 x 6 x 18 mm exclusive of drive and recording electronics. Mass spectrometers as small as 3 x 3 mm, again without electronics, are under development. A variety of compact optical and mass spectrometers are reviewed in this paper. A number of past space applications are described, along with some upcoming opportunities that are likely candidate missions to fly this new class of compact spectrometers.

  18. An improved nuclear magnetic resonance spectrometer

    NASA Technical Reports Server (NTRS)

    Elleman, D. D.; Manatt, S. L.

    1967-01-01

    Cylindrical sample container provides a high degree of nuclear stabilization to a nuclear magnetic resonance /nmr/ spectrometer. It is placed coaxially about the nmr insert and contains reference sample that gives a signal suitable for locking the field and frequency of an nmr spectrometer with a simple audio modulation system.

  19. Multichannel Spectrometer of Time Distribution

    NASA Astrophysics Data System (ADS)

    Akindinova, E. V.; Babenko, A. G.; Vakhtel, V. M.; Evseev, N. A.; Rabotkin, V. A.; Kharitonova, D. D.

    2015-06-01

    For research and control of characteristics of radiation fluxes, radioactive sources in particular, for example, in paper [1], a spectrometer and methods of data measurement and processing based on the multichannel counter of time intervals of accident events appearance (impulses of particle detector) MC-2A (SPC "ASPECT") were created. The spectrometer has four independent channels of registration of time intervals of impulses appearance and correspondent amplitude and spectrometric channels for control along the energy spectra of the operation stationarity of paths of each of the channels from the detector to the amplifier. The registration of alpha-radiation is carried out by the semiconductor detectors with energy resolution of 16-30 keV. Using a spectrometer there have been taken measurements of oscillations of alpha-radiation 239-Pu flux intensity with a subsequent autocorrelative statistical analysis of the time series of readings.

  20. Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR) Instrument Improvements

    NASA Technical Reports Server (NTRS)

    Dunagan, Stephen E.; Redemann, Jens; Chang, Cecilia; Dahlgren, Robert; Fahey, Lauren; Flynn, Connor; Johnson, Roy; Kacenelenbogen, Meloe; Leblanc, Samuel; Liss, Jordan; hide

    2017-01-01

    The Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR) combines airborne sun tracking and sky scanning with grating spectroscopy to improve knowledge of atmospheric constituents and their links to air-pollution and climate. Hyper-spectral measurements of direct-beam solar irradiance provide retrievals of gas constituents, aerosol optical depth, and aerosol and thin cloud optical properties. Sky radiance measurements in the principal and almucantar planes enhance retrievals of aerosol absorption, aerosol type, and size mode distribution. Zenith radiance measurements are used to retrieve cloud properties and phase, which in turn are used to quantify the radiative transfer below cloud layers. These airborne measurements tighten the closure between satellite and ground-based measurements. In contrast to the Ames Airborne Tracking Sunphotometer (AATS-14) predecessor instrument, new technologies for each subsystem have been incorporated into 4STAR. In particular, 4STAR utilizes a modular sun-trackingsky-scanning optical head with fiber optic signal transmission to rack mounted spectrometers, permitting miniaturization of the external optical head, and spectrometerdetector configurations that may be tailored for specific scientific objectives. This paper discusses technical challenges relating to compact optical collector design, radiometric dynamic range and stability, and broad spectral coverage at high resolution. Test results benchmarking the performance of the instrument against the AATS-14 standard and emerging science requirements are presented.

  1. Using a portable terahertz spectrometer to measure the optical properties of in vivo human skin

    NASA Astrophysics Data System (ADS)

    Echchgadda, Ibtissam; Grundt, Jessica E.; Tarango, Melissa; Ibey, Bennett L.; Tongue, Thomas; Liang, Min; Xin, Hao; Wilmink, Gerald J.

    2013-02-01

    Terahertz time-domain spectroscopy (THz-TDS) systems are capable of detecting small differences in water concentration levels in biological tissues. This feature makes THz devices excellent tools for the noninvasive assessment of skin; however, most conventional systems prove too cumbersome for limited-space environments. We previously demonstrated that a portable, compact THz spectrometer permitted measurement of porcine skin optical properties that were comparable to those collected with conventional systems. In order to move toward human use of this system, the goal for this study was to collect the optical properties, specifically the absorption coefficient (μa) and index of refraction (n), of human subjects in vivo. Spectra were collected from 0.1-2 THz, and measurements were made on the palm, ventral (inner) and dorsal (outer) forearm. Prior to each THz measurement, we used a multiprobe adapter system to measure each subject's skin hydration levels, transepidermal waterloss (TEWL), skin color, and degree of melanin pigmentation. Our results suggest that the measured optical properties were wide-ranging, and varied considerably for skin tissues with different hydration and melanin levels. These data provide a novel framework for accurate human tissue measurements using THz spectrometers in limited-space environments.

  2. Determination of sulfur in kerosene by combustion and molecular absorption spectrometry in the gas phase

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

    Ruschak, M.L.; Syty, A.

    1982-08-01

    A technique of nonflame molecular adsorption in the gas phase developed for the determination of sulfite trapped in tetrachloromercurate, is described herein for application to the determination of total sulfur in kerosene. The burner head is removed from the atomic absorption spectrometer and replaced with a flow-through absorption cell. A special reaction vessel is used to evolve SO/sub 2/ from the sulfite in a precise and convenient manner. The transient absorbance caused by the SO/sub 2/, as it is carried through the absorption cell, is measured. Both spiked and unspiked samples of kerosene were analyzed, and the reproducibility of themore » repeated runs is evidenced by a relative standard deviation from the mean of 5% for the unspiked kerosene and 4% for the spiked kerosene. If the detection level is defined as that concentration of S which gives a % S twice the standard deviation from the mean yields, the detection limit for the present method is 0.002% S by weight in kerosene.« less

  3. Spectrometer gun

    DOEpatents

    Waechter, D.A.; Wolf, M.A.; Umbarger, C.J.

    1981-11-03

    A hand-holdable, battery-operated, microprocessor-based spectrometer gun is described that includes a low-power matrix display and sufficient memory to permit both real-time observation and extended analysis of detected radiation pulses. Universality of the incorporated signal processing circuitry permits operation with various detectors having differing pulse detection and sensitivity parameters.

  4. Uncertainty budgets for liquid waveguide CDOM absorption measurements.

    PubMed

    Lefering, Ina; Röttgers, Rüdiger; Utschig, Christian; McKee, David

    2017-08-01

    Long path length liquid waveguide capillary cell (LWCC) systems using simple spectrometers to determine the spectral absorption by colored dissolved organic matter (CDOM) have previously been shown to have better measurement sensitivity compared to high-end spectrophotometers using 10 cm cuvettes. Information on the magnitude of measurement uncertainties for LWCC systems, however, has remained scarce. Cross-comparison of three different LWCC systems with three different path lengths (50, 100, and 250 cm) and two different cladding materials enabled quantification of measurement precision and accuracy, revealing strong wavelength dependency in both parameters. Stable pumping of the sample through the capillary cell was found to improve measurement precision over measurements made with the sample kept stationary. Results from the 50 and 100 cm LWCC systems, with higher refractive index cladding, showed systematic artifacts including small but unphysical negative offsets and high-frequency spectral perturbations due to limited performance of the salinity correction. In comparison, the newer 250 cm LWCC with lower refractive index cladding returned small positive offsets that may be physically correct. After null correction of measurements at 700 nm, overall agreement of CDOM absorption data at 440 nm was found to be within 5% root mean square percentage error.

  5. Ultra High Mass Range Mass Spectrometer System

    DOEpatents

    Reilly, Peter T. A. [Knoxville, TN

    2005-12-06

    Applicant's present invention comprises mass spectrometer systems that operate in a mass range from 1 to 10.sup.16 DA. The mass spectrometer system comprising an inlet system comprising an aerodynamic lens system, a reverse jet being a gas flux generated in an annulus moving in a reverse direction and a multipole ion guide; a digital ion trap; and a thermal vaporization/ionization detector system. Applicant's present invention further comprises a quadrupole mass spectrometer system comprising an inlet system having a quadrupole mass filter and a thermal vaporization/ionization detector system. Applicant's present invention further comprises an inlet system for use with a mass spectrometer system, a method for slowing energetic particles using an inlet system. Applicant's present invention also comprises a detector device and a method for detecting high mass charged particles.

  6. A Low Cost Grism Spectrometer for Small Telescopes

    NASA Astrophysics Data System (ADS)

    Ludovici, Dominic

    2016-06-01

    We have designed and built a low cost (appx. $500) low resolution (R ~ 300) grating-prism (grism) spectrometer for the University of Iowa's robotic observatory. Grism spectrometers differ from simple transmission grating systems by partially compensating for the curved focal plane using a wedge prism. The spectrometer has five optical elements, and was designed using a ray tracing program. The collimating and focusing optics are easily modified for other telescope optics. The optics are mounted in an enclosure made with a 3-d printer. The spectrometer was installed in a modified (extended) filter wheel and has been in routine operation since January 2016. I will show sample spectra using this system and discuss spectral calibration, and optical design considerations for other telescopes. I will also discuss how low-resolution spectrometers can be used in undergraduate teaching laboratories.

  7. Method and Apparatus for Accurately Calibrating a Spectrometer

    NASA Technical Reports Server (NTRS)

    Youngquist, Robert C. (Inventor); Simmons, Stephen M. (Inventor)

    2013-01-01

    A calibration assembly for a spectrometer is provided. The assembly includes a spectrometer having n detector elements, where each detector element is assigned a predetermined wavelength value. A first source emitting first radiation is used to calibrate the spectrometer. A device is placed in the path of the first radiation to split the first radiation into a first beam and a second beam. The assembly is configured so that one of the first and second beams travels a path-difference distance longer than the other of the first and second beams. An output signal is generated by the spectrometer when the first and second beams enter the spectrometer. The assembly includes a controller operable for processing the output signal and adapted to calculate correction factors for the respective predetermined wavelength values assigned to each detector element.

  8. Artificial intelligence for geologic mapping with imaging spectrometers

    NASA Technical Reports Server (NTRS)

    Kruse, F. A.

    1993-01-01

    This project was a three year study at the Center for the Study of Earth from Space (CSES) within the Cooperative Institute for Research in Environmental Science (CIRES) at the University of Colorado, Boulder. The goal of this research was to develop an expert system to allow automated identification of geologic materials based on their spectral characteristics in imaging spectrometer data such as the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). This requirement was dictated by the volume of data produced by imaging spectrometers, which prohibits manual analysis. The research described is based on the development of automated techniques for analysis of imaging spectrometer data that emulate the analytical processes used by a human observer. The research tested the feasibility of such an approach, implemented an operational system, and tested the validity of the results for selected imaging spectrometer data sets.

  9. Collision-induced absorption in the region of the ν2 + ν3 band of carbon dioxide

    NASA Astrophysics Data System (ADS)

    Baranov, Yu. I.

    2018-03-01

    The IR absorption spectra of pure carbon dioxide in the region of the forbidden ν2 + ν3 vibrational transition at 3004 cm-1 have been recorded using a Fourier-transform spectrometer. A multipass-optical cell with the path length of 100 m was used in the study. The data were taken at room temperature of 294.8 K with a resolution of 0.02 cm-1 over the spectral region 2500-3500 cm-1. A sample pressures varied from 207 to 463 kPa (2.04-4.57 atm). The measured binary absorption coefficients provide the band integrated intensity value of (2.39 ± 0.04) ∗ 10-4 cm-2 amagat-2. The result is compared with those from previous works. The observed band profile features are discussed.

  10. Detection of metal stress in boreal forest species using the 0.67-micron chlorophyll absorption band

    NASA Technical Reports Server (NTRS)

    Singhroy, Vernon H.; Kruse, Fred A.

    1991-01-01

    Several recent studies have shown that a shift of the red-edge inflection near 0.70 micron in vegetation reflectance spectra is an indicator of metal stress, partially attributable to changes in chlorophyll concentration. This 'red-edge shift', however, is difficult to detect and has been reported both toward longer (red) and shorter (blue) wavelengths. Our work demonstrates that direct measurement of the depth and width of the chlorophyll absorption band at 0.67 micron using digital feature extraction and absorption band characterization procedures developed for the analysis of mineral spectra is a more consistent indicator of metal stress. Additionally, the magnitude of these parameters is generally greater than that of the red edge shift and thus should be more amenable to detection and mapping using field and aircraft spectrometers.

  11. Sharp Absorption Peaks in THz Spectra Valuable for Crystal Quality Evaluation of Middle Molecular Weight Pharmaceuticals

    NASA Astrophysics Data System (ADS)

    Sasaki, Tetsuo; Sakamoto, Tomoaki; Otsuka, Makoto

    2018-05-01

    Middle molecular weight (MMW) pharmaceuticals (MW 400 4000) are attracting attention for their possible use in new medications. Sharp absorption peaks were observed in MMW pharmaceuticals at low temperatures by measuring with a high-resolution terahertz (THz) spectrometer. As examples, high-resolution THz spectra for amoxicillin trihydrate, atorvastatin calcium trihydrate, probucol, and α,β,γ,δ-tetrakis(1-methylpyridinium-4-yl)porphyrin p-toluenesulfonate (TMPyP) were obtained at 10 K. Typically observed as peaks with full width at half-height (FWHM) values as low as 5.639 GHz at 0.96492 THz in amoxicillin trihydrate and 8.857 GHz at 1.07974 THz for probucol, many sharp peaks of MMW pharmaceuticals could be observed. Such narrow absorption peaks enable evaluation of the crystal quality of MMW pharmaceuticals and afford sensitive detection of impurities.

  12. Fast Infrared Exoplanet Spectroscopy Survey Explorer (FINESSE) prism spectrometer

    NASA Astrophysics Data System (ADS)

    McGuire, James P.

    2017-11-01

    The FINESSE spectrometer design (0.45 to 5 μm at a resolution of greater than 80 at f/12) is placed in context by reviewing history of unit magnification relays and spectrometers. Related imaging spectrometers are also described.

  13. Constraints on the Compositions of Phobos and Deimos from Mineral Absorptions

    NASA Technical Reports Server (NTRS)

    Fraeman, A. A.; Murchie, S. L.; Arvidson, R. E.; Rivkin, A. S.; Morris, R. V.

    2013-01-01

    The compositions of Phobos and Deimos have remained controversial despite multiple Earth- and space-based observations acquired during the last 40 years. Phobos is composed of at least two spectral units that are both dark yet distinct at visible to near infrared wavelenghts; a spectrally red-sloped "red" unit covers most of the moon and a less red-sloped "blue" unit is present in the ejecta of the approximately 9-km diameter impact crater Stickney [1,2]. Deimos is similar spectrally to Phobos' "red" unit [2]. Here we report results from mapping mineral absorptions on Phobos and Deimos using visible/near infrared observations from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). We find evidence for an absorption feature at 0.65 m in the Phobos red unit and Deimos that is reproducible in observations from other instruments. The phase responsible is uncertain but may be a Fe-bearing phyllosilicate and/or graphite, consistent with the notion that Phobos and Deimos have compositions similar to CM carbonaceous chondrites [3].

  14. Tunable far infrared laser spectrometers

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

    Blake, G.A.; Laughlin, K.B.; Cohen, R.C.

    The state of the art in far infrared (FIR) spectroscopy is reviewed. The development of tunable, coherent FIR radiation sources is discussed. Applications of tunable FIR laser spectrometers for measurement of rotational spectra and dipole moments of molecular ions and free radicals, vibration-rotation-tunneling (VRT) spectra of weakly bound complexes, and vibration-rotation spectra of linear carbon clusters are presented. A detailed description of the Berkeley tunable FIR laser spectrometers is presented in the following article.

  15. Determination of technical readiness for an atmospheric carbon imaging spectrometer

    NASA Astrophysics Data System (ADS)

    Mobilia, Joseph; Kumer, John B.; Palmer, Alice; Sawyer, Kevin; Mao, Yalan; Katz, Noah; Mix, Jack; Nast, Ted; Clark, Charles S.; Vanbezooijen, Roel; Magoncelli, Antonio; Baraze, Ronald A.; Chenette, David L.

    2013-09-01

    The geoCARB sensor uses a 4-channel push broom slit-scan infrared imaging grating spectrometer to measure the absorption spectra of sunlight reflected from the ground in narrow wavelength regions. The instrument is designed for flight at geostationary orbit to provide mapping of greenhouse gases over continental scales, several times per day, with a spatial resolution of a few kilometers. The sensor provides multiple daily maps of column-averaged mixing ratios of CO2, CH4, and CO over the regions of interest, which enables flux determination at unprecedented time, space, and accuracy scales. The geoCARB sensor development is based on our experience in successful implementation of advanced space deployed optical instruments for remote sensing. A few recent examples include the Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic Imager (HMI) on the geostationary Solar Dynamics Observatory (SDO), the Space Based Infrared System (SBIRS GEO-1) and the Interface Region Imaging Spectrograph (IRIS), along with sensors under development, the Near Infared camera (NIRCam) for James Webb (JWST), and the Global Lightning Mapper (GLM) and Solar UltraViolet Imager (SUVI) for the GOES-R series. The Tropospheric Infrared Mapping Spectrometer (TIMS), developed in part through the NASA Instrument Incubator Program (IIP), provides an important part of the strong technological foundation for geoCARB. The paper discusses subsystem heritage and technology readiness levels for these subsystems. The system level flight technology readiness and methods used to determine this level are presented along with plans to enhance the level.

  16. Compact hydrogen/helium isotope mass spectrometer

    DOEpatents

    Funsten, Herbert O.; McComas, David J.; Scime, Earl E.

    1996-01-01

    The compact hydrogen and helium isotope mass spectrometer of the present invention combines low mass-resolution ion mass spectrometry and beam-foil interaction technology to unambiguously detect and quantify deuterium (D), tritium (T), hydrogen molecule (H.sub.2, HD, D.sub.2, HT, DT, and T.sub.2), .sup.3 He, and .sup.4 He concentrations and concentration variations. The spectrometer provides real-time, high sensitivity, and high accuracy measurements. Currently, no fieldable D or molecular speciation detectors exist. Furthermore, the present spectrometer has a significant advantage over traditional T detectors: no confusion of the measurements by other beta-emitters, and complete separation of atomic and molecular species of equivalent atomic mass (e.g., HD and .sup.3 He).

  17. OH/H2O Detection Capability Evaluation on Chang'e-5 Lunar Mineralogical Spectrometer (LMS)

    NASA Astrophysics Data System (ADS)

    Liu, Bin; Ren, Xin; Liu, Jianjun; Li, Chunlai; Mu, Lingli; Deng, Liyan

    2016-10-01

    The Chang'e-5 (CE-5) lunar sample return mission is scheduled to launch in 2017 to bring back lunar regolith and drill samples. The Chang'e-5 Lunar Mineralogical Spectrometer (LMS), as one of the three sets of scientific payload installed on the lander, is used to collect in-situ spectrum and analyze the mineralogical composition of the samplingsite. It can also help to select the sampling site, and to compare the measured laboratory spectrum of returned sample with in-situ data. LMS employs acousto-optic tunable filters (AOTFs) and is composed of a VIS/NIR module (0.48μm-1.45μm) and an IR module (1.4μm -3.2μm). It has spectral resolution ranging from 3 to 25 nm, with a field of view (FOV) of 4.24°×4.24°. Unlike Chang'e-3 VIS/NIR Imaging Spectrometer (VNIS), the spectral coverage of LMS is extended from 2.4μm to 3.2μm, which has capability to identify H2O/OH absorption features around 2.7μm. An aluminum plate and an Infragold plate are fixed in the dust cover, being used as calibration targets in the VIS/NIR and IR spectral range respectively when the dust cover is open. Before launch, a ground verification test of LMS needs to be conducted in order to: 1) test and verify the detection capability of LMS through evaluation on the quality of image and spectral data collected for the simulated lunar samples; and 2) evaluate the accuracy of data processing methods by the simulation of instrument working on the moon. The ground verification test will be conducted both in the lab and field. The spectra of simulated lunar regolith/mineral samples will be collected simultaneously by the LMS and two calibrated spectrometers: a FTIR spectrometer (Model 102F) and an ASD FieldSpec 4 Hi-Res spectrometer. In this study, the results of the LMS ground verification test will be reported, and OH/H2O Detection Capability will be evaluated especially.

  18. Broad-Bandwidth FPGA-Based Digital Polyphase Spectrometer

    NASA Technical Reports Server (NTRS)

    Jamot, Robert F.; Monroe, Ryan M.

    2012-01-01

    With present concern for ecological sustainability ever increasing, it is desirable to model the composition of Earth s upper atmosphere accurately with regards to certain helpful and harmful chemicals, such as greenhouse gases and ozone. The microwave limb sounder (MLS) is an instrument designed to map the global day-to-day concentrations of key atmospheric constituents continuously. One important component in MLS is the spectrometer, which processes the raw data provided by the receivers into frequency-domain information that cannot only be transmitted more efficiently, but also processed directly once received. The present-generation spectrometer is fully analog. The goal is to include a fully digital spectrometer in the next-generation sensor. In a digital spectrometer, incoming analog data must be converted into a digital format, processed through a Fourier transform, and finally accumulated to reduce the impact of input noise. While the final design will be placed on an application specific integrated circuit (ASIC), the building of these chips is prohibitively expensive. To that end, this design was constructed on a field-programmable gate array (FPGA). A family of state-of-the-art digital Fourier transform spectrometers has been developed, with a combination of high bandwidth and fine resolution. Analog signals consisting of radiation emitted by constituents in planetary atmospheres or galactic sources are downconverted and subsequently digitized by a pair of interleaved analog-to-digital converters (ADCs). This 6-Gsps (gigasample per second) digital representation of the analog signal is then processed through an FPGA-based streaming fast Fourier transform (FFT). Digital spectrometers have many advantages over previously used analog spectrometers, especially in terms of accuracy and resolution, both of which are particularly important for the type of scientific questions to be addressed with next-generation radiometers.

  19. Time-resolved measurements of black carbon light absorption enhancement in urban and near-urban locations of Southern Ontario, Canada

    NASA Astrophysics Data System (ADS)

    Chan, T. W.; Brook, J. R.; Smallwood, G. J.; Lu, G.

    2010-08-01

    In this study a photoacoustic spectrometer (PA), a laser-induced incandescence instrument system (LII) and an aerosol mass spectrometer were operated in parallel for in situ measurements of black carbon (BC) light absorption enhancement. Results of a thermodenuder experiment using ambient particles in Toronto are presented first to show that LII measurements of BC are not influenced by particle coating while the PA response is enhanced and also that the nature of this enhancement is influenced by particle morphology. Comparisons of ambient PA and LII measurements at four different locations (suburban Toronto; a street canyon with heavy diesel bus traffic in Ottawa; adjacent to a commuter highway in Ottawa and; regional background air in and around Windsor, Ontario), show that the different meteorological conditions and atmospheric processes result in different particle light absorption enhancement and hence the specific attenuation coefficient (SAC). Depending upon location of measurement and the BC spherule diameter (primary particle size - PPS) measurement from the LII, the SAC varies from 2.6±0.04 to 22.5±0.7 m2 g-1. Observations from this study also show the active surface area of the BC aggregate, inferred from PPS, is an important parameter for inferring the degree of particle collapse of a BC particle. The predictability of the overall BC light absorption enhancement in the atmosphere depends not only on the coating mass but also on the source of the BC and on our ability to predict or measure the change in particle morphology as particles evolve.

  20. Miniaturized spectrometer for stand-off chemical detection

    NASA Astrophysics Data System (ADS)

    Henning, Patrick F.; Chadha, Suneet; Damren, Richard; Rowe, Rebecca C.; Stevenson, Chuck; Curtiss, Lawrence E.; DiGiuseppe, Thomas G.

    2002-02-01

    Advanced autonomous detection of both chemical warfare agents and toxic industrial chemicals has long been of major military concern and is becoming an increasingly realistic need. Foster-Miller has successfully designed and demonstrated a high spectral throughput monolithic wedge spectrometer capable of providing early, stand-off detection of chemical threats. Recent breakthrough innovations in IR source technologies, high D* multispectral array detectors, and IR waveguide materials has allowed for the development of a robust, miniature, monolithic infrared spectrometer. Foster-Miller recently demonstrated a high resolution spectrometer operating in the 8 to 12 micron region for chemical agent detection. Results will be presented demonstrating the feasibility of adapting the wedge spectrometer to operate as an upward looking ground sensor for stand-off chemical detection. Our miniaturized spectrometer forms the basis for deploying low cost, lightweight sensors which may be used for reconnaissance missions or delivered to remote locations for unattended operation. The ability of perform passive stand-off infrared chemical agent and chemical emissions detection with a low cost, compact device that can operate autonomously in remote environments has broad applications in both the military and commercial marketplace.

  1. Broad band waveguide spectrometer

    DOEpatents

    Goldman, Don S.

    1995-01-01

    A spectrometer for analyzing a sample of material utilizing a broad band source of electromagnetic radiation and a detector. The spectrometer employs a waveguide possessing an entry and an exit for the electromagnetic radiation emanating from the source. The waveguide further includes a surface between the entry and exit portions which permits interaction between the electromagnetic radiation passing through the wave guide and a sample material. A tapered portion forms a part of the entry of the wave guide and couples the electromagnetic radiation emanating from the source to the waveguide. The electromagnetic radiation passing from the exit of the waveguide is captured and directed to a detector for analysis.

  2. Performance of the EBIT calorimeter spectrometer

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

    Porter, Frederick Scott; Gygax, John; Kelley, Richard L.

    The EBIT calorimeter spectrometer (ECS) is a new high-resolution, broadband x-ray spectrometer that has recently been installed at the Electron Beam Ion Trap Facility (EBIT) at the Lawrence Livermore National Laboratory. The ECS is an entirely new production class spectrometer that replaces the XRS/EBIT spectrometer that has been operating at EBIT since 2000. The ECS utilizes a 32-pixel x-ray calorimeter array from the XRS instrument on the Suzaku x-ray observatory. Eighteen of the pixels are optimized for the 0.1-10 keV band and yield 4.5 eV full width at half maximum energy resolution and 95% quantum efficiency at 6 keV. Inmore » addition, the ECS includes 14 detector pixels that are optimized for the high-energy band with a bandpass from 0.5 to over 100 keV with 34 eV resolution and 32% quantum efficiency at 60 keV. The ECS detector array is operated at 50 mK using a five stage cryogenic system that is entirely automated. The instrument takes data continuously for over 65 h with a 2.5 h recycle time. The ECS is a nondispersive, broadband, highly efficient spectrometer that is one of the prime instruments at the EBIT facility. The instrument is used for studies of absolute cross sections, charge exchange recombination, and x-ray emission from nonequilibrium plasmas, among other measurements in our laboratory astrophysics program.« less

  3. Radiation calibration for LWIR Hyperspectral Imager Spectrometer

    NASA Astrophysics Data System (ADS)

    Yang, Zhixiong; Yu, Chunchao; Zheng, Wei-jian; Lei, Zhenggang; Yan, Min; Yuan, Xiaochun; Zhang, Peizhong

    2014-11-01

    The radiometric calibration of LWIR Hyperspectral imager Spectrometer is presented. The lab has been developed to LWIR Interferometric Hyperspectral imager Spectrometer Prototype(CHIPED-I) to study Lab Radiation Calibration, Two-point linear calibration is carried out for the spectrometer by using blackbody respectively. Firstly, calibration measured relative intensity is converted to the absolute radiation lightness of the object. Then, radiation lightness of the object is is converted the brightness temperature spectrum by the method of brightness temperature. The result indicated †that this method of Radiation Calibration calibration was very good.

  4. New scientific results with SpIOMM: a testbed for CFHT's imaging Fourier transform spectrometer SITELLE

    NASA Astrophysics Data System (ADS)

    Drissen, L.; Alarie, A.; Martin, T.; Lagrois, D.; Rousseau-Nepton, L.; Bilodeau, A.; Robert, C.; Joncas, G.; Iglesias-Páramo, J.

    2012-09-01

    We present new data obtained with SpIOMM, the imaging Fourier transform spectrometer attached to the 1.6-m telescope of the Observatoire du Mont-Megantic in Québec. Recent technical and data reduction improvements have significantly increased SpIOMM's capabilities to observe fainter objects or weaker nebular lines, as well as continuum sources and absorption lines, and to increase its modulation efficiency in the near ultraviolet. To illustrate these improvements, we present data on the supernova remnant Cas A, planetary nebulae M27 and M97, the Wolf-Rayet ring nebula M1-67, spiral galaxies M63 and NGC 3344, as well as the interacting pair of galaxies Arp 84.

  5. Frequency-agile, rapid scanning spectroscopy: absorption sensitivity of 2 × 10-12 cm-1 Hz-1/2 with a tunable diode laser

    NASA Astrophysics Data System (ADS)

    Long, D. A.; Truong, G.-W.; van Zee, R. D.; Plusquellic, D. F.; Hodges, J. T.

    2014-03-01

    We present ultrasensitive measurements of molecular absorption using frequency-agile rapid scanning, cavity ring-down spectroscopy with an external-cavity diode laser. A microwave source that drives an electro-optic phase modulator with a bandwidth of 20 GHz generates pairs of sidebands on the probe laser. The optical cavity provides for high sensitivity and filters the carrier and all but a single, selected sideband. Absorption spectra were acquired by stepping the tunable sideband from mode-to-mode of the ring-down cavity at a rate that was limited only by the cavity decay time. This approach allows for scanning rates of 8 kHz per cavity resonance, a minimum detectable absorption coefficient of 1.7 × 10-11 cm-1 after only 20 ms of averaging, and a noise-equivalent absorption coefficient of 1.7 × 10-12 cm-1 Hz-1/2. By comparison with cavity-enhanced laser absorption spectrometers reported in the literature, the present system is, to the best of our knowledge, among the most sensitive and has by far the highest spectrum scanning rate.

  6. Mini ion trap mass spectrometer

    DOEpatents

    Dietrich, Daniel D.; Keville, Robert F.

    1995-01-01

    An ion trap which operates in the regime between research ion traps which can detect ions with a mass resolution of better than 1:10.sup.9 and commercial mass spectrometers requiring 10.sup.4 ions with resolutions of a few hundred. The power consumption is kept to a minimum by the use of permanent magnets and a novel electron gun design. By Fourier analyzing the ion cyclotron resonance signals induced in the trap electrodes, a complete mass spectra in a single combined structure can be detected. An attribute of the ion trap mass spectrometer is that overall system size is drastically reduced due to combining a unique electron source and mass analyzer/detector in a single device. This enables portable low power mass spectrometers for the detection of environmental pollutants or illicit substances, as well as sensors for on board diagnostics to monitor engine performance or for active feedback in any process involving exhausting waste products.

  7. Mini ion trap mass spectrometer

    DOEpatents

    Dietrich, D.D.; Keville, R.F.

    1995-09-19

    An ion trap is described which operates in the regime between research ion traps which can detect ions with a mass resolution of better than 1:10{sup 9} and commercial mass spectrometers requiring 10{sup 4} ions with resolutions of a few hundred. The power consumption is kept to a minimum by the use of permanent magnets and a novel electron gun design. By Fourier analyzing the ion cyclotron resonance signals induced in the trap electrodes, a complete mass spectra in a single combined structure can be detected. An attribute of the ion trap mass spectrometer is that overall system size is drastically reduced due to combining a unique electron source and mass analyzer/detector in a single device. This enables portable low power mass spectrometers for the detection of environmental pollutants or illicit substances, as well as sensors for on board diagnostics to monitor engine performance or for active feedback in any process involving exhausting waste products. 10 figs.

  8. Airborne imaging spectrometers developed in China

    NASA Astrophysics Data System (ADS)

    Wang, Jianyu; Xue, Yongqi

    1998-08-01

    Airborne imaging spectral technology, principle means in airborne remote sensing, has been developed rapidly both in the world and in China recently. This paper describes Modular Airborne Imaging Spectrometer (MAIS), Operational Modular Airborne Imaging Spectrometer (OMAIS) and Pushbroom Hyperspectral Imagery (PHI) that have been developed or are being developed in Airborne Remote Sensing Lab of Shanghai Institute of Technical Physics, CAS.

  9. Coupling of the recoil mass spectrometer CAMEL to the γ-ray spectrometer GASP

    NASA Astrophysics Data System (ADS)

    Spolaore, P.; Ackermann, D.; Bednarczyk, P.; De Angelis, G.; Napoli, D.; Rossi Alvarez, C.; Bazzacco, D.; Burch, R.; Müller, L.; Segato, G. F.; Scarlassara, F.

    1995-02-01

    A project has been realized to link the CAMEL recoil mass spectrometer to the GASP γ-spectrometer in order to perform high resolution and efficiency γ-recoil coincidence measurements. To preserve high flexibility and autonomy in the operation of the two complex apparatus a rough factor two of reduction in the overall heavy ion transmission was accepted in designing the optics of the particle transport from the GASP center to the CAMEL focal plane. The coupled configuration has been tested with the fusion reaction 58Ni (E = 212 MeV) + 64Ni, obtaining a mass resolution of {1}/{300} and efficiency between ˜ 11% and ˜ 15% for different evaporation products.

  10. ExoMars Raman laser spectrometer overview

    NASA Astrophysics Data System (ADS)

    Rull, F.; Sansano, A.; Díaz, E.; Canora, C. P.; Moral, A. G.; Tato, C.; Colombo, M.; Belenguer, T.; Fernández, M.; Manfredi, J. A. R.; Canchal, R.; Dávila, B.; Jiménez, A.; Gallego, P.; Ibarmia, S.; Prieto, J. A. R.; Santiago, A.; Pla, J.; Ramos, G.; González, C.

    2010-09-01

    The Raman Laser Spectrometer (RLS) is one of the Pasteur Payload instruments, within the ESA's Aurora Exploration Programme, ExoMars mission. The RLS Instrument will perform Raman spectroscopy on crushed powered samples deposited on a small container after crushing the cores obtained by the Rover's drill system. This is the first time that a Raman spectrometer will be launched in an out planetary mission. The Instrument will be accommodated and operate inside the Rover's ALD (Analytical Laboratory Drawer), complying with COSPAR (Committee on Space Research) Planetary Protection requirements. The RLS Instrument is composed by the following units: SPU (Spectrometer Unit); iOH: (Internal Optical Head); ICEU (Instrument Control and Excitation Unit). Other instrument units are EH (Electrical Harness), OH (Optical Harness) and RLS SW On-Board.

  11. Kα X-Ray Emission Spectra and K X-Ray Absorption-Edge Structures of Fluorine in 3d Transition-Metal Difluorides

    NASA Astrophysics Data System (ADS)

    Sugiura, Chikara

    1991-08-01

    The fluorine Kα emission spectra in fluorescence from a series of 3d transition-metal difluorides MF2 (M=Mn, Fe, Co, Ni, Cu and Zn) have been measured with a high-resolution two-crystal vacuum spectrometer. It is shown that the observed FWHM of the Kα1,2 emission band is closely related to the difference in the electronegativity between the metal and fluorine atoms. The measured emission spectra are presented along with the UPS or XPS spectra of the valence bands and the fluorine K absorption spectra of the metal difluorides, reported previously. The structures at the fluorine K absorption edges are interpreted in terms of a molecular orbital (MO) model.

  12. AUTOMATIC MASS SPECTROMETER

    DOEpatents

    Hanson, M.L.; Tabor, C.D. Jr.

    1961-12-01

    A mass spectrometer for analyzing the components of a gas is designed which is capable of continuous automatic operation such as analysis of samples of process gas from a continuous production system where the gas content may be changing. (AEC)

  13. Differentially pumped dual linear quadrupole ion trap mass spectrometer

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

    Owen, Benjamin C.; Kenttamaa, Hilkka I.

    The present disclosure provides a new tandem mass spectrometer and methods of using the same for analyzing charged particles. The differentially pumped dual linear quadrupole ion trap mass spectrometer of the present disclose includes a combination of two linear quadrupole (LQIT) mass spectrometers with differentially pumped vacuum chambers.

  14. Design considerations regarding an atomizer for multi-element electrothermal atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Katskov, Dmitri A.; Sadagov, Yuri M.

    2011-06-01

    The methodology of simultaneous multi-element electrothermal atomic absorption spectrometry (ETAAS-Electrothermal Atomic Absorption Spectrometry) stipulates rigid requirements to the design and operation of the atomizer. It must provide high degree of atomization for the group of analytes, invariant respective to the vaporization kinetics and heating ramp residence time of atoms in the absorption volume and absence of memory effects from major sample components. For the low resolution spectrometer with a continuum radiation source the reduced compared to traditional ETAAS (Electrothermal Atomic Absorption Spectrometry) sensitivity should be, at least partially, compensated by creating high density of atomic vapor in the absorption pulse. The sought-for characteristics were obtained for the 18 mm in length and 2.5 mm in internal diameter longitudinally heated graphite tube atomizer furnished with 2-4.5 mg of ring shaped carbon fiber yarn collector. The collector located next to the sampling port provides large substrate area that helps to keep the sample and its residue in the central part of the tube after drying. The collector also provides a "platform" effect that delays the vaporization and stipulates vapor release into absorption volume having already stabilized gas temperature. Due to the shape of external surface of the tube, presence of collector and rapid (about 10 °C/ms) heating, an inverse temperature distribution along the tube is attained at the beginnings of the atomization and cleaning steps. The effect is employed for cleaning of the atomizer using the set of short maximum power heating pulses. Preparation, optimal maintenance of the atomizer and its compliance to the multi-element determination requirements are evaluated and discussed. The experimental setup provides direct simultaneous determination of large group of element within 3-4 order concentration range. Limits of detection are close to those for sequential single element determination in

  15. The Spectrometer

    ERIC Educational Resources Information Center

    Greenslade, Thomas B., Jr.

    2012-01-01

    In the fall of 1999 I was shown an Ocean Optics spectrometer-in-the-computer at St. Patricks College at Maynooth, Ireland, and thought that I had seen heaven. Of course, it could not resolve the sodium D-lines (I had done that many years before with a homemade wire diffraction grating), and I began to realize that inside was some familiar old…

  16. Compact characterization of liquid absorption and emission spectra using linear variable filters integrated with a CMOS imaging camera

    NASA Astrophysics Data System (ADS)

    Wan, Yuhang; Carlson, John A.; Kesler, Benjamin A.; Peng, Wang; Su, Patrick; Al-Mulla, Saoud A.; Lim, Sung Jun; Smith, Andrew M.; Dallesasse, John M.; Cunningham, Brian T.

    2016-07-01

    A compact analysis platform for detecting liquid absorption and emission spectra using a set of optical linear variable filters atop a CMOS image sensor is presented. The working spectral range of the analysis platform can be extended without a reduction in spectral resolution by utilizing multiple linear variable filters with different wavelength ranges on the same CMOS sensor. With optical setup reconfiguration, its capability to measure both absorption and fluorescence emission is demonstrated. Quantitative detection of fluorescence emission down to 0.28 nM for quantum dot dispersions and 32 ng/mL for near-infrared dyes has been demonstrated on a single platform over a wide spectral range, as well as an absorption-based water quality test, showing the versatility of the system across liquid solutions for different emission and absorption bands. Comparison with a commercially available portable spectrometer and an optical spectrum analyzer shows our system has an improved signal-to-noise ratio and acceptable spectral resolution for discrimination of emission spectra, and characterization of colored liquid’s absorption characteristics generated by common biomolecular assays. This simple, compact, and versatile analysis platform demonstrates a path towards an integrated optical device that can be utilized for a wide variety of applications in point-of-use testing and point-of-care diagnostics.

  17. Compact characterization of liquid absorption and emission spectra using linear variable filters integrated with a CMOS imaging camera.

    PubMed

    Wan, Yuhang; Carlson, John A; Kesler, Benjamin A; Peng, Wang; Su, Patrick; Al-Mulla, Saoud A; Lim, Sung Jun; Smith, Andrew M; Dallesasse, John M; Cunningham, Brian T

    2016-07-08

    A compact analysis platform for detecting liquid absorption and emission spectra using a set of optical linear variable filters atop a CMOS image sensor is presented. The working spectral range of the analysis platform can be extended without a reduction in spectral resolution by utilizing multiple linear variable filters with different wavelength ranges on the same CMOS sensor. With optical setup reconfiguration, its capability to measure both absorption and fluorescence emission is demonstrated. Quantitative detection of fluorescence emission down to 0.28 nM for quantum dot dispersions and 32 ng/mL for near-infrared dyes has been demonstrated on a single platform over a wide spectral range, as well as an absorption-based water quality test, showing the versatility of the system across liquid solutions for different emission and absorption bands. Comparison with a commercially available portable spectrometer and an optical spectrum analyzer shows our system has an improved signal-to-noise ratio and acceptable spectral resolution for discrimination of emission spectra, and characterization of colored liquid's absorption characteristics generated by common biomolecular assays. This simple, compact, and versatile analysis platform demonstrates a path towards an integrated optical device that can be utilized for a wide variety of applications in point-of-use testing and point-of-care diagnostics.

  18. Development of a Gas Filled Magnet spectrometer coupled with the Lohengrin spectrometer for fission study

    NASA Astrophysics Data System (ADS)

    Kessedjian, G.; Chebboubi, A.; Faust, H.; Köster, U.; Materna, T.; Sage, C.; Serot, O.

    2013-03-01

    The accurate knowledge of the fission of actinides is necessary for studies of innovative nuclear reactor concepts. The fission yields have a direct influence on the evaluation of the fuel inventory or the reactor residual power after shutdown. A collaboration between the ILL, LPSC and CEA has developed a measurement program on fission fragment distributions at ILL in order to measure the isotopic and isomeric yields. The method is illustrated using the 233U(n,f)98Y reaction. However, the extracted beam from the Lohengrin spectrometer is not isobaric ions which limits the low yield measurements. Presently, the coupling of the Lohengrin spectrometer with a Gas Filled Magnet (GFM) is studied at the ILL in order to define and validate the enhanced purification of the extracted beam. This work will present the results of the spectrometer characterisation, along with a comparison with a dedicated Monte Carlo simulation especially developed for this purpose.

  19. Multimodal optical setup based on spectrometer and cameras combination for biological tissue characterization with spatially modulated illumination

    NASA Astrophysics Data System (ADS)

    Baruch, Daniel; Abookasis, David

    2017-04-01

    The application of optical techniques as tools for biomedical research has generated substantial interest for the ability of such methodologies to simultaneously measure biochemical and morphological parameters of tissue. Ongoing optimization of optical techniques may introduce such tools as alternative or complementary to conventional methodologies. The common approach shared by current optical techniques lies in the independent acquisition of tissue's optical properties (i.e., absorption and reduced scattering coefficients) from reflected or transmitted light. Such optical parameters, in turn, provide detailed information regarding both the concentrations of clinically relevant chromophores and macroscopic structural variations in tissue. We couple a noncontact optical setup with a simple analysis algorithm to obtain absorption and scattering coefficients of biological samples under test. Technically, a portable picoprojector projects serial sinusoidal patterns at low and high spatial frequencies, while a spectrometer and two independent CCD cameras simultaneously acquire the reflected diffuse light through a single spectrometer and two separate CCD cameras having different bandpass filters at nonisosbestic and isosbestic wavelengths in front of each. This configuration fills the gaps in each other's capabilities for acquiring optical properties of tissue at high spectral and spatial resolution. Experiments were performed on both tissue-mimicking phantoms as well as hands of healthy human volunteers to quantify their optical properties as proof of concept for the present technique. In a separate experiment, we derived the optical properties of the hand skin from the measured diffuse reflectance, based on a recently developed camera model. Additionally, oxygen saturation levels of tissue measured by the system were found to agree well with reference values. Taken together, the present results demonstrate the potential of this integrated setup for diagnostic and

  20. [Development of X-ray excited fluorescence spectrometer].

    PubMed

    Ni, Chen; Gu, Mu; Di, Wang; Cao, Dun-Hua; Liu, Xiao-Lin; Huang, Shi-Ming

    2009-08-01

    An X-ray excited fluorescence spectrometer was developed with an X-ray tube and a spectrometer. The X-ray tube, spectrometer, autocontrol method and data processing selected were roundly evaluated. The wavelength and detecting efficiency of the apparatus were calibrated with the mercury and tungsten bromine standard lamps, and the X-ray excited emission spectra of BaF2, Cs I (Tl) crystals were measured. The results indicate that the apparatus has advantages of good wavelength resolution, high stability, easy to operation and good radioprotection. It is a wery effective tool for exploration of new scintillation materials.

  1. Airborne Measurements of Formaldehyde Employing a Tunable Diode Laser Absorption Spectrometer During TRACE-P

    NASA Technical Reports Server (NTRS)

    Fried, Alan; Drummond, James

    2003-01-01

    This final report summarizes the progress achieved over the entire 3-year proposal period including two extensions spanning 1 year. These activities include: 1) Preparation for and participation in the NASA 2001 TRACE-P campaign using our airborne tunable diode laser system to acquire measurements of formaldehyde (CH2O); 2) Comprehensive data analysis and data submittal to the NASA archive; 3) Follow up data interpretation working with NASA modelers to place our ambient CH2O measurements into a broader photochemical context; 4) Publication of numerous JGR papers using this data; 5) Extensive follow up laboratory tests on the selectivity and efficiency of our CH20 scrubbing system; and 6) An extensive follow up effort to assess and study the mechanical stability of our entire optical system, particularly the multipass absorption cell, with aircraft changes in cabin pressure.

  2. Mass Spectrometer for Airborne Micro-Organisms

    NASA Technical Reports Server (NTRS)

    Sinha, M. P.; Friedlander, S. K.

    1986-01-01

    Bacteria and other micro-organisms identified continously with aid of new technique for producing samples for mass spectrometer. Technique generates aerosol of organisms and feeds to spectrometer. Given species of organism produces characteristic set of peaks in mass spectrum and thereby identified. Technique useful for monitoring bacterial makeup in environmental studies and in places where cleanliness is essential, such as hospital operating rooms, breweries, and pharmaceutical plants.

  3. Oceanic Gas Bubble Measurements Using an Acoustic Bubble Spectrometer

    NASA Astrophysics Data System (ADS)

    Wilson, S. J.; Baschek, B.; Deane, G.

    2008-12-01

    Gas bubble injection by breaking waves contributes significantly to the exchange of gases between atmosphere and ocean at high wind speeds. In this respect, CO2 is primarily important for the global ocean and climate, while O2 is especially relevant for ecosystems in the coastal ocean. For measuring oceanic gas bubble size distributions, a commercially available Dynaflow Acoustic Bubble Spectrometer (ABS) has been modified. Two hydrophones transmit and receive selected frequencies, measuring attenuation and absorption. Algorithms are then used to derive bubble size distributions. Tank test were carried out in order to test the instrument performance.The software algorithms were compared with Commander and Prosperetti's method (1989) of calculating sound speed ratio and attenuation for a known bubble distribution. Additional comparisons with micro-photography were carried out in the lab and will be continued during the SPACE '08 experiment in October 2008 at Martha's Vineyard Coastal Observatory. The measurements of gas bubbles will be compared to additional parameters, such as wind speed, wave height, white cap coverage, or dissolved gases.

  4. ComPAQS: a compact concentric UV/visible spectrometer, providing a new tool for air quality monitoring from space

    NASA Astrophysics Data System (ADS)

    Leigh, Roland J.; Whyte, C.; Cutter, M. A.; Lobb, D. R.; Monks, P. S.

    2017-11-01

    Under the first phase of the Centre for Earth Observation Instrumentation (CEOI), a breadboard demonstrator of a novel UV/VIS spectrometer has been developed. Using designs from Surrey Satellite Technology Ltd (SSTL) the demonstrator has been constructed and tested at the University of Leicester's Space Research Centre. This spectrometer provides an exceptionally compact instrument for differential optical absorption spectroscopy (DOAS) applications from LEO, GEO, HAP or ground-based platforms. Measurement of atmo spheric compounds with climate change or air quality implications is a key driver for the ground and space-based Earth Observation communities. Techniques using UV/VIS spectroscopy such as DOAS provide measurements of ozone profiles, aerosol optical depth, certain Volatile Organic Compounds, halogenated species, and key air quality parameters including tropospheric nitrogen dioxide. Compact instruments providing the necessary optical performance and spectral resolution are therefore a key enabling technology. The Compact Air Quality Spectrometer (CompAQS) features a concentric arrangement of a spherical meniscus lens, a concave spherical mirror and a suitable curved diffraction grating. This compact design provides efficiency and performance benefits over traditional concepts, improving the precision and spatial resolution available from space borne instruments with limited weight and size budgets. The breadboard spectrometer currently operating at the University of Leicester offers high throughput with a spectral range from 310 to 450 nm at 0.5nm(UV) to 1.0nm (visible) resolution, suitable for DOAS applications. The concentric design is capable of handling high relative apertures, owing to spherical aberration and coma being near zero at all surfaces. The design also provides correction for transverse chromatic aberration and distortion, in addition to correcting for the distortion called `smile' - the curvature of the slit image formed at each

  5. Multichannel Dynamic Fourier-Transform IR Spectrometer

    NASA Astrophysics Data System (ADS)

    Balashov, A. A.; Vaguine, V. A.; Golyak, Il. S.; Morozov, A. N.; Khorokhorin, A. I.

    2017-09-01

    A design of a multichannel continuous scan Fourier-transform IR spectrometer for simultaneous recording and analysis of the spectral characteristics of several objects is proposed. For implementing the design, a multi-probe fiber is used, constructed from several optical fibers connected into a single optical connector and attached at the output of the interferometer. The Fourier-transform spectrometer is used as a signal modulator. Each fiber is individually mated with an investigated sample and a dedicated radiation detector. For the developed system, the radiation intensity of the spectrometer is calculated from the condition of the minimum spectral resolution and parameters of the optical fibers. Using the proposed design, emission spectra of a gas-discharge neon lamp have been recorded using a single fiber 1 mm in diameter with a numerical aperture NA = 0.22.

  6. Improved real-time imaging spectrometer

    NASA Technical Reports Server (NTRS)

    Lambert, James L. (Inventor); Chao, Tien-Hsin (Inventor); Yu, Jeffrey W. (Inventor); Cheng, Li-Jen (Inventor)

    1993-01-01

    An improved AOTF-based imaging spectrometer that offers several advantages over prior art AOTF imaging spectrometers is presented. The ability to electronically set the bandpass wavelength provides observational flexibility. Various improvements in optical architecture provide simplified magnification variability, improved image resolution and light throughput efficiency and reduced sensitivity to ambient light. Two embodiments of the invention are: (1) operation in the visible/near-infrared domain of wavelength range 0.48 to 0.76 microns; and (2) infrared configuration which operates in the wavelength range of 1.2 to 2.5 microns.

  7. A cometary ion mass spectrometer

    NASA Technical Reports Server (NTRS)

    Shelley, E. G.; Simpson, D. A.

    1984-01-01

    The development of flight suitable analyzer units for that part of the GIOTTO Ion Mass Spectrometer (IMS) experiment designated the High Energy Range Spectrometer (HERS) is discussed. Topics covered include: design of the total ion-optical system for the HERS analyzer; the preparation of the design of analyzing magnet; the evaluation of microchannel plate detectors and associated two-dimensional anode arrays; and the fabrication and evaluation of two flight-suitable units of the complete ion-optical analyzer system including two-dimensional imaging detectors and associated image encoding electronics.

  8. Spectral Anomalies in the 11 and 12 micron Region From the Mariner Mars 7 Infrared Spectrometer

    NASA Technical Reports Server (NTRS)

    Kirkland, Laurel E.; Herr, Kenneth C.

    2000-01-01

    Two hundred-forty infrared spectra acquired by the 1969 Mariner Mars 7 Infrared Spectrometer (IRS), spanning the wavelength region 1.8-14.4 micron (5550-690/cm), have recently been recovered and calibrated in both wavelength and intensity. An examination of these IRS spectra has revealed absorptions at 11.25 and 12.5 micron that have not previously been reported for Mars. A search of the literature and spectral data bases shows that materials that exhibit a doublet at 11.25 and 12.5 micron are rare. In this paper we examine potential causes for these features and include a detailed discussion of carbonates, goethite, CO2 ice, and water ice. CO2 ice and water ice measured in transmission do not exhibit bands that match those recorded at 11.25 and 12.5 micron for Mars, which indicates that CO2 or water ice clouds are not the source of these features. Since these bands show no clear correlation with atmospheric path length, they are most likely caused by a surface material. In the IRS database they appear to be exceptionally intense in the western part of the Hellas basin. Goethite exhibits bands that are a good spectral match, but confirming whether goethite causes the features will require additional studies of the 20-50 micron region. These studies will require laboratory measurements of weathering coatings and an examination of spectra recorded of Mars by the 1971 Mariner Mars Infrared Interferometer Spectrometer (IRIS; 5-50 micron 2000200/cm) and the 1996 Thermal Emission Spectrometer (TES; 6-50 micron 1667-200/cm).

  9. Infrared fiber coupled acousto-optic tunable filter spectrometer

    NASA Technical Reports Server (NTRS)

    Levin, K. H.; Kindler, E.; Ko, T.; Lee, F.; Tran, D. C.; Tapphorn, R. M.

    1990-01-01

    A spectrometer design is introduced which combines an acoustooptic tunable filter (AOTF) and IR-transmitting flouride-glass fibers. The AOTF crystal is fabricated from TeO2 and permits random access to any wavelength in less than 50 microseconds, and the resulting spectrometer is tested for the remote analysis of gases and hydrocarbons. The AOTF spectrometer, when operated with a high-speed frequency synthesizer and optimized algorithms, permits accurate high-speed spectroscopy in the mid-IR spectral region.

  10. Application of a mass spectrometer as a capnograph

    NASA Astrophysics Data System (ADS)

    Elokhin, V. A.; Ershov, T. D.; Levshankov, A. I.; Nikolaev, V. I.; Elizarov, A. Yu.

    2010-12-01

    The feasibility of using a mass spectrometer for monitoring the carbon dioxide and inhalational anesthetic concentrations in the breathing circuit of an apparatus for inhalational anesthesia are demonstrated. Mass-spectrometric data for the CO2 and inhalational anesthetic concentrations are compared with related optical data. The advantages of the mass spectrometer as a capnograph over the optical spectrometer are indicated. The variation of the inhalational anesthetic content in expired air is shown to depend on the muscle relaxation efficiency.

  11. A high performance neutron spectrometer for planetary hydrogen measurement

    NASA Astrophysics Data System (ADS)

    Naito, Masayuki; Hasebe, Nobuyuki; Nagaoka, Hiroshi; Ishii, Junya; Aoki, Daisuke; Shibamura, Eido; Kim, Kyeong J.; Matias-Lopes, José A.; Martínez-Frías, Jesús

    2017-08-01

    The elemental composition and its distribution on planetary surface provide important constraints on the origin and evolution of the planetary body. The nuclear spectrometer consisting of a neutron spectrometer and a gamma-ray spectrometer obtains elemental compositions by remote sensing. Especially, the neutron spectrometer is able to determine the hydrogen concentration, a piece of information that plays an important role in thermal history of the planets. In this work, numerical and experimental studies on the neutron spectrometer for micro-satellite application were conducted. It is found that background count rate of neutron produced from micro-satellite is very small, which enables to obtain successful results in short time observation. The neutron spectrometer combining a lithium-6 glass scintillator with a boron loaded plastic scintillator was used to be able to detect neutrons in different energy ranges. It was experimentally confirmed that the neutron signals from these scintillators were successfully discriminated by the difference of scintillation decay time between two detectors. The measurement of neutron count rates of two scintillators is found to determine hydrogen concentration on the planetary surfaces in the future missions.

  12. On the evaluation of air mass factors for atmospheric near-ultraviolet and visible absorption spectroscopy

    NASA Technical Reports Server (NTRS)

    Perliski, Lori M.; Solomon, Susan

    1993-01-01

    The interpretation of UV-visible twilight absorption measurements of atmospheric chemical constituents is dependent on how well the optical path, or air mass factor, of light collected by the spectrometer is understood. A simple single scattering model and a Monte Carlo radiative transfer scheme have been developed to study the effects of multiple scattering, aerosol scattering, surface albedo and refraction on air mass factors for scattered light observations. At fairly short visible wavelengths (less than about 450 nm), stratospheric air mass factors are found to be relatively insensitive to multiple scattering, surface albedo and refraction, as well as aerosol scattering by background aerosols. Longer wavelengths display greater sensitivity to refraction and aerosol scattering. Tropospheric air mass factors are found to be highly dependent on aerosol scattering, surface albedo and, at long visible wavelengths (about 650 nm), refraction. Absorption measurements of NO2 and O4 are shown to support these conclusions.

  13. Underresolved absorption spectroscopy of OH radicals in flames using broadband UV LEDs

    NASA Astrophysics Data System (ADS)

    White, Logan; Gamba, Mirko

    2018-04-01

    A broadband absorption spectroscopy diagnostic based on underresolution of the spectral absorption lines is evaluated for the inference of species mole fraction and temperature in combustion systems from spectral fitting. The approach uses spectrally broadband UV light emitting diodes and leverages low resolution, small form factor spectrometers. Through this combination, the method can be used to develop high precision measurement sensors. The challenges of underresolved spectroscopy are explored and addressed using spectral derivative fitting, which is found to generate measurements with high precision and accuracy. The diagnostic is demonstrated with experimental measurements of gas temperature and OH mole fraction in atmospheric air/methane premixed laminar flat flames. Measurements exhibit high precision, good agreement with 1-D flame simulations, and high repeatability. A newly developed model of uncertainty in underresolved spectroscopy is applied to estimate two-dimensional confidence regions for the measurements. The results of the uncertainty analysis indicate that the errors in the outputs of the spectral fitting procedure are correlated. The implications of the correlation between uncertainties for measurement interpretation are discussed.

  14. A high-resolution oxygen A-band spectrometer (HABS) and its radiation closure

    NASA Astrophysics Data System (ADS)

    Min, Q.; Yin, B.; Li, S.; Berndt, J.; Harrison, L.; Joseph, E.; Duan, M.; Kiedron, P.

    2014-02-01

    The pressure dependence of oxygen A-band absorption enables the retrieval of the vertical profiles of aerosol and cloud properties from oxygen A-band spectrometry. To improve the understanding of oxygen A-band inversions and utility, we developed a high-resolution oxygen A-band spectrometer (HABS), and deployed it at Howard University Beltsville site during the NASA Discover Air-Quality Field Campaign in July 2011. The HABS has the ability to measure solar direct-beam and zenith diffuse radiation through a telescope automatically. It exhibits excellent performance: stable spectral response ratio, high signal-to-noise ratio (SNR), high spectrum resolution (0.16 nm), and high Out-of-Band Rejection (10-5). To evaluate the spectra performance of HABS, a HABS simulator has been developed by combing the discrete ordinates radiative transfer (DISORT) code with the High Resolution Transmission (HTRAN) database HITRAN2008. The simulator uses double-k approach to reduce the computational cost. The HABS measured spectra are consistent with the related simulated spectra. For direct-beam spectra, the confidence intervals (95%) of relative difference between measurements and simulation are (-0.06, 0.05) and (-0.08, 0.09) for solar zenith angles of 27° and 72°, respectively. The main differences between them occur at or near the strong oxygen absorption line centers. They are mainly caused by the noise/spikes of HABS measured spectra, as a result of combined effects of weak signal, low SNR, and errors in wavelength registration and absorption line parameters. The high-resolution oxygen A-band measurements from HABS can constrain the active radar retrievals for more accurate cloud optical properties, particularly for multi-layer clouds and for mixed-phase clouds.

  15. X-RAY ABSORPTION BY THE WARM-HOT INTERGALACTIC MEDIUM IN THE HERCULES SUPERCLUSTER

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

    Ren, Bin; Fang, Taotao; Buote, David A., E-mail: fangt@xmu.edu.cn

    2014-02-10

    ''Missing baryons'', in the form of warm-hot intergalactic medium (WHIM), are expected to reside in cosmic filamentary structures that can be traced by signposts such as large-scale galaxy superstructures. The clear detection of an X-ray absorption line in the Sculptor Wall demonstrated the success of using galaxy superstructures as a signpost to search for the WHIM. Here we present an XMM -Newton Reflection Grating Spectrometer observation of the blazar Mkn 501, located in the Hercules Supercluster. We detected an O VII Kα absorption line at the 98.7% level (2.5σ) at the redshift of the foreground Hercules Supercluster. The derived properties of themore » absorber are consistent with theoretical expectations of the WHIM. We discuss the implication of our detection for the search for the ''missing baryons''. While this detection shows again that using signposts is a very effective strategy to search for the WHIM, follow-up observations are crucial both to strengthen the statistical significance of the detection and to rule out other interpretations. A local, z ∼ 0 O VII Kα absorption line was also clearly detected at the 4σ level, and we discuss its implications for our understanding of the hot gas content of our Galaxy.« less

  16. Adapting Raman Spectra from Laboratory Spectrometers to Portable Detection Libraries

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

    Weatherall, James; Barber, Jeffrey B.; Brauer, Carolyn S.

    2013-02-01

    Raman spectral data collected with high-resolution laboratory spectrometers are processed into a for- mat suitable for importing as a user library on a 1064nm DeltaNu rst generation, eld-deployable spectrometer prototype. The two laboratory systems used are a 1064nm Bruker spectrometer and a 785nm Kaiser spectrometer. The steps taken to compensate for device-dependent spectral resolution, wavenumber shifts between instruments, and wavenumber sensitivity variation are described.

  17. The high-resolution time-of-flight spectrometer TOFTOF

    NASA Astrophysics Data System (ADS)

    Unruh, Tobias; Neuhaus, Jürgen; Petry, Winfried

    2007-10-01

    The TOFTOF spectrometer is a multi-disc chopper time-of-flight spectrometer for cold neutrons at the research neutron source Heinz Maier-Leibnitz (FRM II). After five reactor cycles of routine operation the characteristics of the instrument are reported in this article. The spectrometer features an excellent signal to background ratio due to its remote position in the neutron guide hall, an elaborated shielding concept and an s-shaped curved primary neutron guide which acts i.a. as a neutron velocity filter. The spectrometer is fed with neutrons from the undermoderated cold neutron source of the FRM II leading to a total neutron flux of ˜1010n/cm2/s in the continuous white beam at the sample position distributed over a continuous and particularly broad wavelength spectrum. A high energy resolution is achieved by the use of high speed chopper discs made of carbon-fiber-reinforced plastic. In the combination of intensity, resolution and signal to background ratio the spectrometer offers new scientific prospects in the fields of inelastic and quasielastic neutron scattering.

  18. Performance of the Fourier transform spectrometer (FTS) for FIS onboard ASTRO-F

    NASA Astrophysics Data System (ADS)

    Murakami, Noriko; Kawada, Mitsunobu; Takahashi, Hidenori; Ozawa, Keita; Imamura, Tetsuo; Shibai, Hiroshi; Nakagawa, Takao

    2004-10-01

    We have developed the imaging Fourier Transform Spectrometer (FTS) for the FIS (Far-Infrared Surveyor) onboard the ASTRO-F satellite. A Martin-Puplett interferometer is adopted to achieve high optical efficiency in a wide wavelength range. The total optical efficiency of this spectrometer is achieved 40-80% of the ideal value which is 25% of the incident flux. The wavelength range of 50-200μm is covered with two kinds of detector; the monolithic Ge:Ga photoconductor array for short wavelength (50-110μm) and the stressed Ge:Ga photoconductor array for long wavelength (110-200μm). The spectral resolution expected from the maximum optical path difference is 0.18cm-1. In order to evaluate the spectral resolution of the FTS, we measured absorption lines of H2O in atmosphere using the optics of the FTS with a bolometer at the room temperature. The measured line widths are consistent with the expected instrumental resolution of 0.18 cm-1. Some spectral measurements at the cryogenic temperature were carried out by using cold blackbody sources whose temperatures are controlled in a range from 20 to 50 K. The derived spectra considering with the spectral response of the system are consistent with expected ones. Spectroscopic observations with the FTS will provide a lot of astronomical information; SED of galaxies detected in the all sky survey and the physical diagnostics of the interstellar matter by using the excited atomic or molecular lines.

  19. Very high S-band microwave absorption of carbon nanotube buckypapers with Mn nanoparticle interlayers

    NASA Astrophysics Data System (ADS)

    Lu, Shaowei; Bai, Yaoyao; Wang, Jijie; Zhang, Lu; Tian, Caijiao; Ma, Keming; Wang, Xiaoqiang

    2018-03-01

    Flexible and high-performance electromagnetic absorbing materials of multi-walled carbon nanotube (MWCNT) buckypapers with Mn nanoparticles (NPSs) interlayer were fabricated via monodisperse solutions through layer by layer vacuum filtration method. The morphology and element composition of buckypapers were characterized by scanning electron microscopy, energy dispersive spectrometer, and X-ray diffraction. The formation of flexible MWCNT buckypapers with Mn NPS (0-30 wt. %) interlayer was attributed to nanostructure and morphology of the samples. When the blended Mn NPS content in buckypapers is 20 wt. %, there are evidently two larger absorption peaks (-13.2 dB at 3.41 GHz, -15.6 dB at 3.52 GHz) of the buckypaper with an absorbing thickness of 0.1 mm. The fundamental microwave absorption mechanism of the buckypapers is discussed. This work opens a new pathway towards tuning microwave absorbers performance and this method can be extended to exploit other excellent microwave absorbers with interlayer.

  20. Advances in OLED/OPD-based sensors and spectrometer-on-a-chip (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Shinar, Joseph; Kaudal, Rajiv; Manna, Eeshita; Fungura, Fadzai; Shinar, Ruth

    2016-09-01

    We describe ongoing advances toward achieving all-organic optical sensors and a spectrometer on a chip. Two-dimensional combinatorial arrays of microcavity OLEDs (μcOLEDs) with systematically varying optical cavity lengths are fabricated on a single chip by changing the thickness of different organic and/or spacer layers sandwiched between two metal electrodes (one very thin) that form the cavity. The broad spectral range is achieved by utilizing materials that result in white OLEDs (WOLEDs) when fabricated on a standard ITO substrate. The tunable and narrower emissions from the μcOLEDs serve as excitation sources in luminescent sensors and in monitoring light absorption. For each wavelength, the light from the μcOLED is partially absorbed by a sample under study and the light emitted by an electronically excited sample, or the transmitted light is detected by a photodetector (PD). To obtain a compact monitor, an organic PD (OPD) or a perovskite-based PD is integrated with the μcOLED array. We show the potential of encompassing a broader wavelength range by using WOLED materials to fabricate the μcOLEDs. The utility of the all-organic analytical devices is demonstrated by monitoring oxygen, and bioanalytes based on oxygen detection, as well as the absorption spectra of dyes.

  1. MEOS Microsatellite Earth Observation using Miniature Integrated-Optic IR Spectrometers

    NASA Astrophysics Data System (ADS)

    Kruzelecky, Roman

    future, the MEOS Miniature Earth Observing Satellite will innovatively combine remote atmospheric/land-cover measurements with ecosystem modelling in near real-time to obtain simultaneous variations in lower tropospheric GHG mixing ratios and the resulting responses of surface ecosystems. MEOS will provide lower tropospheric CO2 , CH4 , CO, N2 O, H2 O and aerosol mixing ratios over natural sources and sinks using two kinds of synergistic observations; a forward limb measurement and a follow-on nadir measurement over the same geographical tangent point. The measurements will be accomplished using separate limb and nadir suites of miniature lineimaging spectrometers and will be spatially coordinated such that the same air mass is observed in both views within a few minutes. The limb data will consist of 16-pixel vertical spectral line imaging to provide 2.5-km vertical resolution, while the corresponding nadir measurements will view sixteen 5 by 10 km2 ground pixels with a 160-km East-West swath width. The separate limb and nadir instrument suites each feature two complementary NIR miniature spectrometers that will operate in parallel, alternating the collected optical signal between the high-resolution Fabry-Perot guided-wave FP-IOSPEC spectrometer with simultaneous multiple microchannels at 0.03 FWHM with SNR>400 and the 1220 to 2450 nm broad-band spectrometer with 1.2 nm FWHM such that one undergoes the illuminated segment of the processing while the other spectrometer undergoes its dark signal processing. This spectral region provides several harmonic optical absorption bands associated with CO2 , CH4 , CO, H2 O and N2 O. The innovative data synergy of the coarse resolution broad-band spectra with the scanned spectral measurements of the trace-gas fine features at 0.03 nm FWHM in multiple microchannels will be used to improve the accuracy of the trace gas retrievals relative to current missions. In addition, the mission will retrieve cloud top pressures to better than

  2. Frequency-Modulation Correlation Spectrometer

    NASA Technical Reports Server (NTRS)

    Margolis, J. S.; Martonchik, J. V.

    1985-01-01

    New type of correlation spectrometer eliminates need to shift between two cells, one empty and one containing reference gas. Electrooptical phase modulator sinusoidally shift frequencies of sample transmission spectrum.

  3. Gas sampling system for a mass spectrometer

    DOEpatents

    Taylor, Charles E; Ladner, Edward P

    2003-12-30

    The present invention relates generally to a gas sampling system, and specifically to a gas sampling system for transporting a hazardous process gas to a remotely located mass spectrometer. The gas sampling system includes a capillary tube having a predetermined capillary length and capillary diameter in communication with the supply of process gas and the mass spectrometer, a flexible tube surrounding and coaxial with the capillary tube intermediate the supply of process gas and the mass spectrometer, a heat transfer tube surrounding and coaxial with the capillary tube, and a heating device in communication the heat transfer tube for substantially preventing condensation of the process gas within the capillary tube.

  4. Use of airborne imaging spectrometer data to map minerals associated with hydrothermally altered rocks in the northern grapevine mountains, Nevada, and California

    USGS Publications Warehouse

    Kruse, F.A.

    1988-01-01

    Three flightlines of Airborne Imaging Spectrometer (AIS) data, acquired over the northern Grapevine Mountains, Nevada, and California, were used to map minerals associated with hydrothermally altered rocks. The data were processed to remove vertical striping, normalized using an equal area normalization, and reduced to reflectance relative to an average spectrum derived from the data. An algorithm was developed to automatically calculate the absorption band parameters band position, band depth, and band width for the strongest absorption feature in each pixel. These parameters were mapped into an intensity, hue, saturation (IHS) color system to produce a single color image that summarized the absorption band information, This image was used to map areas of potential alteration based upon the predicted relationships between the color image and mineral absorption band. Individual AIS spectra for these areas were then examined to identify specific minerals. Two types of alteration were mapped with the AIS data. Areas of quartz-sericite-pyrite alteration were identified based upon a strong absorption feature near 2.21 ??m, a weak shoulder near 2.25 ??m, and a weak absorption band near 2.35 ??m caused by sericite (fine-grained muscovite). Areas of argillic alteration were defined based on the presence of montmorillonite, identified by a weak to moderate absorption feature near 2.21 ??m and the absence of the 2.35 ??m band. Montmorillonite could not be identified in mineral mixtures. Calcite and dolomite were identified based on sharp absorption features near 2.34 and 2.32 ??m, respectively. Areas of alteration identified using the AIS data corresponded well with areas mapped using field mapping, field reflectance spectra, and laboratory spectral measurements. ?? 1988.

  5. Design of a miniature solid state NIR spectrometer

    NASA Astrophysics Data System (ADS)

    Zhang, Hanyi; Wang, Xiaolu L.; Soos, Jolanta I.; Crisp, Joy A.

    1995-06-01

    For aerospace applications a miniature, solid-state near infrared (NIR) spectrometer based on an acousto-optic tunable filter (AOTF) has been developed and built at Brimrose Corp. of America. In this spectrometer a light emitting diode (LED) array as light source, a set of optical fibers as the lightwave transmission route, and a miniature AOTF as a tunable filter were adopted. This approach makes the spectrometer very compact, light-weight, rugged and reliable, with low operating power and long lifetime.

  6. The complex refractive index of atmospheric and model humic-like substances (HULIS) retrieved by a cavity ring down aerosol spectrometer (CRD-AS).

    PubMed

    Dinar, E; Riziq, A Abo; Spindler, C; Erlick, C; Kiss, G; Rudich, Y

    2008-01-01

    Atmospheric aerosols absorb and reflect solar radiation causing surface cooling and heating of the atmosphere. The interaction between aerosols and radiation depends on their complex index of refraction, which is related to the particles' chemical composition. The contribution of light absorbing organic compounds, such as HUmic-LIke Substances (HULIS) to aerosol scattering and absorption is among the largest uncertainties in assessing the direct effect of aerosols on climate. Using a Cavity Ring Down Aerosol Spectrometer (CRD-AS), the complex index of refraction of aerosols containing HULIS extracted from pollution, smoke, and rural continental aerosols, and molecular weight-fractionated fulvic acid was measured at 390 nm and 532 nm. The imaginary part of the refractive index (absorption) substantially increases towards the UV range with increasing molecular weight and aromaticity. At both wavelengths, HULIS extracted from pollution and smoke particles absorb more than HULIS from the rural aerosol. Sensitivity calculations for a pollution-type aerosol containing ammonium sulfate, organic carbon (HULIS), and soot suggests that accounting for absorption by HULIS leads in most cases to a significant decrease in the single scattering albedo and to a significant increase in aerosol radiative forcing efficiency, towards more atmospheric absorption and heating. This indicates that HULIS in biomass smoke and pollution aerosols, in addition to black carbon, can contribute significantly to light absorption in the ultraviolet and visible spectral regions.

  7. Five-Photon Absorption and Selective Enhancement of Multiphoton Absorption Processes

    PubMed Central

    2015-01-01

    We study one-, two-, three-, four-, and five-photon absorption of three centrosymmetric molecules using density functional theory. These calculations are the first ab initio calculations of five-photon absorption. Even- and odd-order absorption processes show different trends in the absorption cross sections. The behavior of all even- and odd-photon absorption properties shows a semiquantitative similarity, which can be explained using few-state models. This analysis shows that odd-photon absorption processes are largely determined by the one-photon absorption strength, whereas all even-photon absorption strengths are largely dominated by the two-photon absorption strength, in both cases modulated by powers of the polarizability of the final excited state. We demonstrate how to selectively enhance a specific multiphoton absorption process. PMID:26120588

  8. Five-Photon Absorption and Selective Enhancement of Multiphoton Absorption Processes.

    PubMed

    Friese, Daniel H; Bast, Radovan; Ruud, Kenneth

    2015-05-20

    We study one-, two-, three-, four-, and five-photon absorption of three centrosymmetric molecules using density functional theory. These calculations are the first ab initio calculations of five-photon absorption. Even- and odd-order absorption processes show different trends in the absorption cross sections. The behavior of all even- and odd-photon absorption properties shows a semiquantitative similarity, which can be explained using few-state models. This analysis shows that odd-photon absorption processes are largely determined by the one-photon absorption strength, whereas all even-photon absorption strengths are largely dominated by the two-photon absorption strength, in both cases modulated by powers of the polarizability of the final excited state. We demonstrate how to selectively enhance a specific multiphoton absorption process.

  9. A review on the applications of portable near-infrared spectrometers in the agro-food industry.

    PubMed

    dos Santos, Cláudia A Teixeira; Lopo, Miguel; Páscoa, Ricardo N M J; Lopes, João A

    2013-11-01

    Industry has created the need for a cost-effective and nondestructive quality-control analysis system. This requirement has increased interest in near-infrared (NIR) spectroscopy, leading to the development and marketing of handheld devices that enable new applications that can be implemented in situ. Portable NIR spectrometers are powerful instruments offering several advantages for nondestructive, online, or in situ analysis: small size, low cost, robustness, simplicity of analysis, sample user interface, portability, and ergonomic design. Several studies of on-site NIR applications are presented: characterization of internal and external parameters of fruits and vegetables; conservation state and fat content of meat and fish; distinguishing among and quality evaluation of beverages and dairy products; protein content of cereals; evaluation of grape ripeness in vineyards; and soil analysis. Chemometrics is an essential part of NIR spectroscopy manipulation because wavelength-dependent scattering effects, instrumental noise, ambient effects, and other sources of variability may complicate the spectra. As a consequence, it is difficult to assign specific absorption bands to specific functional groups. To achieve useful and meaningful results, multivariate statistical techniques (essentially involving regression techniques coupled with spectral preprocessing) are therefore required to extract the information hidden in the spectra. This work reviews the evolution of the use of portable near-infrared spectrometers in the agro-food industry.

  10. Calibration of a High Resolution X-ray Spectrometer for High-Energy-Density Plasmas on NIF

    NASA Astrophysics Data System (ADS)

    Kraus, B.; Gao, L.; Hill, K. W.; Bitter, M.; Efthimion, P.; Schneider, M. B.; Chen, H.; Ayers, J.; Beiersdorfer, P.; Liedahl, D.; Macphee, A. G.; Thorn, D. B.; Bettencourt, R.; Kauffman, R.; Le, H.; Nelson, D.

    2017-10-01

    A high-resolution, DIM-based (Diagnostic Instrument Manipulator) x-ray crystal spectrometer has been calibrated for and deployed at the National Ignition Facility (NIF) to diagnose plasma conditions and mix in ignition capsules near stagnation times. Two conical crystals in the Hall geometry focus rays from the Kr He- α, Ly- α, and He- β complexes onto a streak camera for time-resolved spectra, in order to measure electron density and temperature by observing Stark broadening and relative intensities of dielectronic satellites. Signals from these two crystals are correlated with a third crystal that time-integrates the intervening energy range. The spectrometer has been absolutely calibrated using a microfocus x-ray source, an array of CCD and single-photon-counting detectors, and K- and L-absorption edge filters. Measurements of the integrated reflectivity, energy range, and energy resolution for each crystal will be presented. The implications of the calibration on signal levels from NIF implosions and x-ray filter choices will be discussed. This work was performed under the auspices of the U.S. DoE by Princeton Plasma Physics Laboratory under contract DE-AC02-09CH11466 and by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344.

  11. Effects of temperature-dependent molecular absorption coefficients on the thermal infrared remote sensing of the earth surface

    NASA Technical Reports Server (NTRS)

    Wan, Zhengming; Dozier, Jeff

    1992-01-01

    The effect of temperature-dependent molecular absorption coefficients on thermal infrared spectral signatures measured from satellite sensors is investigated by comparing results from the atmospheric transmission and radiance codes LOWTRAN and MODTRAN and the accurate multiple scattering radiative transfer model ATRAD for different atmospheric profiles. The sensors considered include the operational NOAA AVHRR and two research instruments planned for NASA's Earth Observing System (EOS): MODIS-N (Moderate Resolution Imaging Spectrometer-Nadir-Mode) and ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer). The difference in band transmittance is as large as 6 percent for some thermal bands within atmospheric windows and more than 30 percent near the edges of these atmospheric windows. The effect of temperature-dependent molecular absorption coefficients on satellite measurements of sea-surface temperature can exceed 0.6 K. Quantitative comparison and factor analysis indicate that more accurate measurements of molecular absorption coefficients and better radiative transfer simulation methods are needed to achieve SST accuracy of 0.3 K, as required for global numerical models of climate, and to develop land-surface temperature algorithms at the 1-K accuracy level.

  12. Research on imaging spectrometer using LC-based tunable filter

    NASA Astrophysics Data System (ADS)

    Shen, Zhixue; Li, Jianfeng; Huang, Lixian; Luo, Fei; Luo, Yongquan; Zhang, Dayong; Long, Yan

    2012-09-01

    A liquid crystal tunable filter (LCTF) with large aperture is developed using PDLC liquid crystal. A small scale imaging spectrometer is established based on this tunable filter. This spectrometer can continuously tuning, or random-access selection of any wavelength in the visible and near infrared (VNIR) band synchronized with the imaging processes. Notable characteristics of this spectrometer include the high flexibility control of its operating channels, the image cubes with high spatial resolution and spectral resolution and the strong ability of acclimation to environmental temperature. The image spatial resolution of each tuning channel is almost near the one of the same camera without the LCTF. The spectral resolution is about 20 nm at 550 nm. This spectrometer works normally under 0-50°C with a maximum power consumption of 10 Watts (with exclusion of the storage module). Due to the optimization of the electrode structure and the driving mode of the Liquid Crystal cell, the switch time between adjacent selected channels can be reduced to 20 ms or even shorter. Spectral imaging experiments in laboratory are accomplished to verify the performance of this spectrometer, which indicate that this compact imaging spectrometer works reliably, and functionally. Possible applications of this imaging spectrometer include medical science, protection of historical relics, criminal investigation, disaster monitoring and mineral detection by remote sensing.

  13. Compositional analysis of Hyperion with the Cassini Visual and Infrared Mapping Spectrometer

    NASA Astrophysics Data System (ADS)

    Brad Dalton, J.; Cruikshank, Dale P.; Clark, Roger N.

    2012-08-01

    Compositional mapping of the surface of Hyperion using Cassini Visual and Infrared Mapping Spectrometer (VIMS) observations reveals a heterogeneous surface dominated by water ice accompanied by additional materials. Carbon dioxide, as evidenced by a prominent absorption band centered at 4.26 μm, is distributed over most of the surface, including icy regions. This does not represent exposures of pure CO2 ice, but concentrations of CO2 molecules adsorbed on other materials or complexed in H2O, perhaps as a clathrate (Cruikshank, D.P., Meyer, A.W., Brown, R.H., Clark, R.N., Jaumann, R., Stephan, K., Hibbitts, C.A., Sandford, S.A., Mastrapa, R., Filacchione, G., Dalle Ore, C.M., Nicholson, P.D., Buratti, B.J., McCord, T.B., Nelson, R.M., Dalton, J.B., Baines, K.H., Matson, D.L., The VIMS Team [2010]. Icarus 206, 561-572). Localized deposits of low-albedo material in subcircular depressions exhibit spectral absorptions indicative of C-H in aromatic (3.29 μm) and aliphatic (3.35-3.50 μm) hydrocarbons. An absorption band at 2.42 μm that is also seen on other saturnian satellites, tentatively identified as H2 (Clark, R.N. et al. [2011]. In: Proc. AAS-DPS Meeting, 43, 1563; Clark et al., in preparation, 2012) adsorbed on dark material grains, is also prominent. Our best spectral models included H2O and CO2 ice, with small amounts of nanophase Fe and Fe2O3. Weaker and more spatially scattered absorption features are also found at 4.48, 4.60, and 4.89 μm, although no clear molecular identifications have yet been made. While strongest in the low-albedo deposits, the CO2, hydrocarbon and putative H2 bands vary in strength throughout the icy regions, as do the 4.48-, 4.60- and 4.89-μm bands, suggesting that this background ice is laced with a complex mixture of non-ice compounds.

  14. Tunable light source for use in photoacoustic spectrometers

    DOEpatents

    Bisson, Scott E.; Kulp, Thomas J.; Armstrong, Karla M.

    2005-12-13

    The present invention provides a photoacoustic spectrometer that is field portable and capable of speciating complex organic molecules in the gas phase. The spectrometer has a tunable light source that has the ability to resolve the fine structure of these molecules over a large wavelength range. The inventive light source includes an optical parametric oscillator (OPO) having combined fine and coarse tuning. By pumping the OPO with the output from a doped-fiber optical amplifier pumped by a diode seed laser, the inventive spectrometer is able to speciate mixtures having parts per billion of organic compounds, with a light source that has a high efficiency and small size, allowing for portability. In an alternative embodiment, the spectrometer is scanned by controlling the laser wavelength, thus resulting in an even more compact and efficient design.

  15. Resonant ultrasound spectrometer

    DOEpatents

    Migliori, Albert; Visscher, William M.; Fisk, Zachary

    1990-01-01

    An ultrasound resonant spectrometer determines the resonant frequency spectrum of a rectangular parallelepiped sample of a high dissipation material over an expected resonant response frequency range. A sample holder structure grips corners of the sample between piezoelectric drive and receive transducers. Each transducer is mounted on a membrane for only weakly coupling the transducer to the holder structure and operatively contacts a material effective to remove system resonant responses at the transducer from the expected response range. i.e., either a material such as diamond to move the response frequencies above the range or a damping powder to preclude response within the range. A square-law detector amplifier receives the response signal and retransmits the signal on an isolated shield of connecting cabling to remove cabling capacitive effects. The amplifier also provides a substantially frequency independently voltage divider with the receive transducer. The spectrometer is extremely sensitive to enable low amplitude resonance to be detected for use in calculating the elastic constants of the high dissipation sample.

  16. Automated atomic absorption spectrometric determination of total arsenic in water and streambed materials

    USGS Publications Warehouse

    Fishman, M.

    1977-01-01

    An automated method to determine both inorganic and organic forms of arsenic In water, water-suspended mixtures, and streambed materials Is described. Organic arsenic-containing compounds are decomposed by either ultraviolet radiation or by suHurlc acid-potassium persulfate digestion. The arsenic liberated, with Inorganic arsenic originally present, is reduced to arsine with sodium borohydrlde. The arable Is stripped from the solution with the aid of nitrogen and Is then decomposed In a tube furnace heated to 800 ??C which Is placed in the optical path of an atomic absorption spectrometer. Thirty samples per hour can be analyzed to levels of 1 ??g arsenic per liter.

  17. [Micro Hadamard transform near-infrared spectrometer].

    PubMed

    Zhang, Zhi-hai; Muo, Xiang-xia; Guo, Yuan-jun; Wang, Wei

    2011-07-01

    A new type micro Hadamard transform (HT) near-infrared (NIR) spectrometer is proposed in the present paper. It has a MOEMS (Micro-Opto-Electro-Mechanical Systems) blazed grating HT mask. It has merits of compactness, agility of dynamic mask generation and high scan speed. The structure and theory of this spectrometer are analyzed. The 63-order Hadamard-S matrix and mask are designed. The mask is dynamically generated by program of MOEMS blazed gratings. The spectrum is in agreement with that measured by Shimadzu spectrometer in experiments. It has a wavelength range between 900 and 1 700 nm, spectral resolution of 19 nm, single scan time of 2.4 s, SNR of 44.67:1, optical path of 70 mm x 130 mm, and weight under 1 kg. It can meet the requirement of real time detection and portable application.

  18. High-resolution absorption cross sections of carbon monoxide bands at 295 K between 91.7 and 100.4 nanometers

    NASA Technical Reports Server (NTRS)

    Stark, G.; Yoshino, K.; Smith, Peter L.; Ito, K.; Parkinson, W. H.

    1991-01-01

    Theoretical descriptions of the abundance and excitation of carbon monoxide in interstellar clouds require accurate data on the vacuum-ultraviolet absorption spectrum of the molecule. The 6.65 m spectrometer at the Photon Factory synchrotron light source was used to measure photoabsorption cross sections of CO features between 91.2 and 100.4 nm. These data were recorded at a resolving power of 170,000, more than 20 times greater than that used in previous work.

  19. A Mass Spectrometer Simulator in Your Computer

    ERIC Educational Resources Information Center

    Gagnon, Michel

    2012-01-01

    Introduced to study components of ionized gas, the mass spectrometer has evolved into a highly accurate device now used in many undergraduate and research laboratories. Unfortunately, despite their importance in the formation of future scientists, mass spectrometers remain beyond the financial reach of many high schools and colleges. As a result,…

  20. Hong-Ou-Mandel Gravitational Wave Space spectrometER - HOMER mission

    NASA Astrophysics Data System (ADS)

    Jacinto de Matos, Clovis; Tajmar, Martin

    2018-06-01

    Michelson type gravitational wave detectors measure the strain caused by gravitational waves on the interferometer's arms. Gravitational waves can also cause the rotation of photon's linear polarization vector, thus disturbing the interference of entangled photons in Hong-Ou-Mandel (HOM) interferometers. Here one uses that physical phenomenon to devise a spectrometer for gravitational waves through the implementation of a Hong-Ou-Mandel interferometer in Earth geostationary orbit with a constellation of three different spacecraft in accurate formation flight. We call this mission, the Hong-Ou-Mandel Gravitational Waves Space SpectrometER (HOMER). HOMER will cover the part of the gravitational wave spectrum with wavelengths around λ =105 km, which falls between the long wavelength detection range of LISA, around λ =106 km, and of ground based detectors like LIGO, around λ =103 km. With respect to Michelson type detectors, the proposed concept for the detection and spectral analysis of gravitational waves has the advantage of operating without the need of drag free satellites, however it requires a relative precision of the attitude between satellites of the order of the gravitational waves amplitude δθ / θ ∼ h ∼10-20 , which makes the architecture of the HOMER mission as challenging as the Michelson type space detectors. The difficulty being however transferred from the monitoring of the relative distance between spacecraft (for Michelson antennas) to their relative attitude. By focusing on photons polarization instead of photons phase one can measure the spectrum of the detected gravitational signal. As a bonus, the proposed instrument could also investigate the influence of spacetime curvature on photons quantum entanglement, thus experimentally peering into the relation between general relativity and quantum mechanics, which is currently a subject of high interest in theoretical physics. This paper will describe the HOMER mission concept in general and