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Sample records for absorption spectrometer based

  1. Modular total absorption spectrometer

    NASA Astrophysics Data System (ADS)

    Karny, M.; Rykaczewski, K. P.; Fijałkowska, A.; Rasco, B. C.; Wolińska-Cichocka, M.; Grzywacz, R. K.; Goetz, K. C.; Miller, D.; Zganjar, E. F.

    2016-11-01

    The design and performance of the Modular Total Absorption Spectrometer built and commissioned at the Oak Ridge National Laboratory is presented. The active volume of the detector is approximately one ton of NaI(Tl), which results in very high full γ energy peak efficiency of 71% at 6 MeV and nearly flat efficiency of around 81.5% for low energy γ-rays between 300 keV and 1 MeV. In addition to the high peak efficiency, the modular construction of the detector permits the use of a γ-coincidence technique in data analysis as well as β-delayed neutron observation.

  2. 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.

  3. Supercontinuum based absorption spectrometer for cycle-resolved multiparameter measurements in a rapid compression machine.

    PubMed

    Werblinski, Thomas; Kleindienst, Stefan; Engelbrecht, Rainer; Zigan, Lars; Will, Stefan

    2016-06-10

    A broadband supercontinuum (SC) based absorption spectrometer capable of cycle-resolved multiparameter measurements at internal combustion (IC) engine conditions is presented. Three parameters, temperature, pressure and water mole fraction, were extracted from broadband near-infrared H2O absorption spectra, spanning the wavelength-range from 1340 to 1405.5 nm, which exhibits a large number of specific H2O transitions. The spectrometer is based on spatial domain detection and features a near-infrared line scan camera as a detector. Measurements were performed during a compression cycle of a rapid compression machine comprising a pressure and temperature range from 2.5 to 65 bar and 300 to 900 K, respectively. With the new spectrometer, we are for the first time, based on the authors' knowledge, able to perform measurements based on SC radiation over a complete compression and expansion stroke at measurement rates up to 50 kHz. A detailed overview is provided about the best match algorithm between theory and experiments, including parameters from two different spectral databases, namely the Barber-Tennyson database (BT2) and HITRAN2012. The results indicate that spectral broadening effects are not properly described by theory, especially at pressure levels exceeding 20 bar, which culminates in a clear underestimation of the derived pressure data by SC absorption spectroscopy. Nevertheless, temperature can be determined accurately by performing a three-parameter fit based on water mole fraction, temperature, and pressure. In contrast, making use of pressure transducer data as look-up values and varying only temperature and H2O mole fraction to find the best match leads to a clear overestimation of temperature at elevated pressures.

  4. Surface Plasmon Based Spectrometer

    NASA Astrophysics Data System (ADS)

    Wig, Andrew; Passian, Ali; Boudreaux, Philip; Ferrell, Tom

    2008-03-01

    A spectrometer that uses surface plasmon excitation in thin metal films to separate light into its component wavelengths is described. The use of surface plasmons as a dispersive medium sets this spectrometer apart from prism, grating, and interference based variants and allows for the miniaturization of this device. Theoretical and experimental results are presented for two different operation models. In the first case surface plasmon tunneling in the near field is used to provide transmission spectra of different broad band-pass, glass filters across the visible wavelength range with high stray-light rejection at low resolution as well as absorption spectra of chlorophyll extracted from a spinach leaf. The second model looks at the far field components of surface plasmon scattering.

  5. Microwave spectrometer for saturated absorption experiments.

    PubMed

    Legrand, J; Ségard, B; Krosta, A; Macke, B

    1978-04-01

    A spectrometer has been built to perform Doppler-free saturated absorption experiments in the millimeter range (30-300 GHz); a plane-cylindrical resonator between Stark plates has been used. With that device, inverted Lamb-dips have been observed at 115 GHz with a width 25 times below the Doppler width. However, the essential feature of this apparatus is to allow the application of Stark field typically of 2500 V/cm, leading to such specific uses as the Stark tuned Lamb-dip, level-crossing, and mode-crossing experiments. Typical examples are given and other applications are proposed.

  6. A decay total absorption spectrometer for DESPEC at FAIR

    NASA Astrophysics Data System (ADS)

    Tain, J. L.; Algora, A.; Agramunt, J.; Guadilla, V.; Jordan, M. D.; Montaner-Pizá, A.; Rubio, B.; Valencia, E.; Cano-Ott, D.; Gelletly, W.; Martinez, T.; Mendoza, E.; Podolyák, Zs.; Regan, P.; Simpson, J.; Smith, A. J.; Strachan, J.

    2015-12-01

    This paper presents the design of a total absorption γ-ray spectrometer for the determination of β-decay intensity distributions of exotic nuclear species at the focal plane of the FAIR-NUSTAR Super Fragment Separator. The spectrometer is a key instrument in the DESPEC experiment and the proposed implementation follows extensive design studies and prototype tests. Two options were contemplated, based on NaI(Tl) and LaBr3:Ce inorganic scintillation crystals respectively. Monte Carlo simulations and technical considerations determined the optimal configurations consisting of sixteen 15 × 15 × 25cm3 crystals for the NaI(Tl) option and one hundred and twenty-eight 5.5 × 5.5 × 11cm3 crystals for the LaBr3:Ce option. Minimization of dead material was crucial for maximizing the spectrometer full-energy peak efficiency. Module prototypes were build to verify constructional details and characterize their performance. The measured energy and timing resolution was found to agree rather well with estimates based on simulations of scintillation light transport and collection. The neutron sensitivity of the spectrometer, important when measuring β-delayed neutron emitters, was investigated by means of Monte Carlo simulations.

  7. 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.

  8. Equilibrator-based measurements of dissolved nitrous oxide in the surface ocean using an integrated cavity output laser absorption spectrometer

    NASA Astrophysics Data System (ADS)

    Grefe, I.; Kaiser, J.

    2013-07-01

    A laser-based analyser for nitrous oxide, carbon monoxide and water vapour was coupled to an equilibrator for continuous high-resolution dissolved gas measurements in the surface ocean. Results for nitrous oxide measurements from laboratory tests and field deployments are presented here. Short-term precision for 10 s-average N2O mole fractions at an acquisition rate of 1 Hz was better than 0.2 nmol mol-1 for standard gases and equilibrator measurements. The same precision was achieved for replicate standard gas analyses within 1 h of each other. The accuracy of the equilibrator measurements was verified by comparison with purge-and-trap GC-MS measurements of N2O concentrations in discrete samples from the Southern Ocean and showed agreement to within the 2% measurement uncertainty of the GC-MS method. Measured atmospheric N2O mole fractions agreed with AGAGE values to within 0.4%. The equilibrator response time to concentration changes in water was 142 to 203 s, depending on the headspace flow rate. The system was tested at sea during a north-to-south transect of the Atlantic Ocean. While the subtropical gyres were slightly undersaturated, the equatorial region was a source of nitrous oxide to the atmosphere. The ability to measure at high temporal and spatial resolution revealed sub-mesoscale variability in dissolved N2O concentrations. The magnitude of the observed saturation is in agreement with published data. Mean sea-to-air fluxes in the tropical and subtropical Atlantic ranged between -1.6 and 0.11 μmol m-2d-1 and confirm that the subtropical Atlantic is not an important source region for N2O to the atmosphere, compared to average global fluxes of 0.6 to 2.4 μmol m-2d-1. The system can be easily modified for autonomous operation on voluntary observing ships (VOS). Further work should include an interlaboratory comparison exercise with other methods of dissolved N2O analyses.

  9. Mid-infrared laser absorption spectrometers based upon all-diode laser difference frequency generation and a room temperature quantum cascade laser for the detection of CO, N2O and NO

    NASA Astrophysics Data System (ADS)

    Kasyutich, V. L.; Holdsworth, R. J.; Martin, P. A.

    2008-08-01

    We describe the performance of two mid-infrared laser spectrometers for carbon monoxide, nitrous oxide and nitric oxide detection. The first spectrometer for CO and N2O detection around 2203 cm-1 is based upon all-diode laser difference frequency generation (DFG) in a quasi-phase matched periodically-poled lithium niobate (PPLN) crystal using two continuous-wave room-temperature distributed feedback diode lasers at 859 and 1059 nm. We also report on the performance of a mid-infrared spectrometer for NO detection at ˜ 1900 cm-1 based upon a thermoelectrically-cooled continuous-wave distributed feedback quantum cascade laser (QCL). Both spectrometers had a single-pass optical cell and a thermoelectrically cooled HgCdZnTe photovoltaic detector. Typical minimum detection limits of 2.8 ppmv for CO, 0.6 ppmv for N2O and 2.7 ppmv for NO have been demonstrated for a 100 averaged spectra acquired within 1.25 s and a cell base length of 21 cm at ˜ 100 Torr. Noise-equivalent absorptions of 10-5 and 10-4 Hz-1/2 are typically demonstrated for the QCL and the DFG based spectrometers, respectively.

  10. 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.

  11. 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.

  12. New detector array - the HRIBF Modular Total Absorption Spectrometer

    NASA Astrophysics Data System (ADS)

    Wolinska-Cichocka, Marzena; Rykaczewski, Krzysztof; Karny, Marek; Kuzniak, Aleksandra; Grzywacz, Robert; Rasco, Charlie; Miller, David; Gross, Carl J.; Johnson, Jim

    2011-10-01

    The construction of a new Modular Total Absorption Spectrometer (MTAS) at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory will be presented. The total absorption gamma spectra measured with MTAS will be used to derive a true beta-feeding pattern and resulting beta strength function for fission products. In particular, the measurements of decay heat released by radioactive nuclei produced in nuclear fuels at power reactors will be performed. MTAS is made up of 19 large NaI(Tl) crystals each encapsulated with a 0.8-mm-thick carbon fiber. There are also two 1-mm- thick Silicon Strip Detectors surrounding a moving tape collector that count beta-energy loss signals. The structure is shielded by more than 1-inch of lead around MTAS which reduces background radiation significantly. MTAS efficiency for full energy deposition of gamma ray approaches nearly 90% for 300 keV gammas and over 75% for a 5 MeV gamma transition. Research supported by the DOE Office of Nuclear Physics.

  13. Automated extraction of absorption features from Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) and Geophysical and Environmental Research Imaging Spectrometer (GERIS) data

    NASA Technical Reports Server (NTRS)

    Kruse, Fred A.; Calvin, Wendy M.; Seznec, Olivier

    1988-01-01

    Automated techniques were developed for the extraction and characterization of absorption features from reflectance spectra. The absorption feature extraction algorithms were successfully tested on laboratory, field, and aircraft imaging spectrometer data. A suite of laboratory spectra of the most common minerals was analyzed and absorption band characteristics tabulated. A prototype expert system was designed, implemented, and successfully tested to allow identification of minerals based on the extracted absorption band characteristics. AVIRIS spectra for a site in the northern Grapevine Mountains, Nevada, have been characterized and the minerals sericite (fine grained muscovite) and dolomite were identified. The minerals kaolinite, alunite, and buddingtonite were identified and mapped for a site at Cuprite, Nevada, using the feature extraction algorithms on the new Geophysical and Environmental Research 64 channel imaging spectrometer (GERIS) data. The feature extraction routines (written in FORTRAN and C) were interfaced to the expert system (written in PROLOG) to allow both efficient processing of numerical data and logical spectrum analysis.

  14. 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.

  15. Commissioning of the High Efficiency Total Absorption Spectrometer (HECTOR)

    NASA Astrophysics Data System (ADS)

    Reingold, C. S.; Simon, A.; Spyrou, A.; Naqvi, F.; Dombos, A.; Palmisano, A.; Anderson, T.; Henderson, S. L.; Moylan, S.; Seymour, C.; Skulski, M. A.; Smith, M. K.; Strauss, S. Y.; Vande Kolk, B.

    2016-09-01

    P-process nucleosynthesis occurs in supernovae where the s-process seeds are present, and is responsible for the production of proton-rich nuclei. Photons from SN explosions induce characteristic (γ,n), (γ,p), and (γ , α) reactions. These reactions are typically studied via the inverse reactions. For this purpose, the High Efficiency Total Absorption Spectrometer (HECTOR), a NaI(Tl) summing detector at the University of Notre Dame, was built. The array is designed to make precision cross section measurements for (p, γ) and (α , γ) reactions. HECTOR is composed of 16 separate NaI(Tl) crystals and 32 photomultiplier tubes read by a digital data acquisition system, with gain-matching and summing done offline. The efficiency of HECTOR is about 52.7 (2.0)% for a 60Co source. The commissioning run for HECTOR was performed via measurements of known resonances in the 27Al(p, γ)28Si reaction to determine the efficiency of the array. The first results from HECTOR will be presented, as well as future plans with the array. This work was supported by the National Science Foundation under Grants No. PHY1614442 and PHY1430152 (JINA-CEE).

  16. 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.

  17. Optical microresonators as single-particle absorption spectrometers

    NASA Astrophysics Data System (ADS)

    Heylman, Kevin D.; Thakkar, Niket; Horak, Erik H.; Quillin, Steven C.; Cherqui, Charles; Knapper, Kassandra A.; Masiello, David J.; Goldsmith, Randall H.

    2016-12-01

    Optical measurements of nanoscale objects offer major insights into fundamental biological, material and photonic properties. In absorption spectroscopy, sensitivity limits applications at the nanoscale. Here, we present a new single-particle double-modulation photothermal absorption spectroscopy method that employs on-chip optical whispering-gallery-mode (WGM) microresonators as ultrasensitive thermometers. Optical excitation of a nanoscale object on the microresonator produces increased local temperatures that are proportional to the absorption cross-section of the object. We resolve photothermal shifts in the resonance frequency of the microresonator that are smaller than 100 Hz, orders of magnitude smaller than previous WGM sensing schemes. The application of our new technique to single gold nanorods reveals a dense array of sharp Fano resonances arising from the coupling between the localized surface plasmon of the gold nanorod and the WGMs of the resonator, allowing for the exploration of plasmonic-photonic hybridization. In terms of the wider applicability, our approach adds label-free spectroscopic identification to microresonator-based detection schemes.

  18. A table-top femtosecond time-resolved soft x-ray transient absorption spectrometer

    SciTech Connect

    Leone, Stephen; Loh, Zhi-Heng; Khalil, Munira; Correa, Raoul E.; Leone, Stephen R.

    2008-05-21

    A laser-based, table-top instrument is constructed to perform femtosecond soft x-ray transient absorption spectroscopy. Ultrashort soft x-ray pulses produced via high-order harmonic generation of the amplified output of a femtosecond Ti:sapphire laser system are used to probe atomic core-level transient absorptions in atoms and molecules. The results provide chemically specific, time-resolved dynamics with sub-50-fs time resolution. In this setup, high-order harmonics generated in a Ne-filled capillary waveguide are refocused by a gold-coated toroidal mirror into the sample gas cell, where the soft x-ray light intersects with an optical pump pulse. The transmitted high-order harmonics are spectrally dispersed with a home-built soft x-ray spectrometer, which consists of a gold-coated toroidal mirror, a uniform-line spaced plane grating, and a soft x-ray CCD camera. The optical layout of the instrument, design of the soft x-ray spectrometer, and spatial and temporal characterization of the high-order harmonics are described. Examples of static and time-resolved photoabsorption spectra collected on this apparatus are presented.

  19. 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.

  20. DUVAS (derivative uv-absorption spectrometer): instrument description and operating manual

    SciTech Connect

    Hawthorne, A.R.; Dougherty, J.M.; Metcalfe, C.E.

    1980-11-01

    DUVAS is a real-time, field-portable spectrometer capable of monitoring a variety of aromatic organic vapors and inorganic gases at sub-ppM concentrations. The instrument is a prototype, microcomputer-controlled, derivative ultraviolet (UV) absorption spectrometer (DUVAS) developed primarily for area monitoring at coal conversion facilities, although other important occupational and environmental monitoring applications for compounds such as SO/sub 2/, NO/sub x/, NH/sub 3/, and HCHO are also being pursued.

  1. Data processing and calibration for tunable diode laser harmonic absorption spectrometers

    NASA Technical Reports Server (NTRS)

    May, Randy D.; Webster, Christopher R.

    1993-01-01

    Data processing and calibration methods are described for tunable diode laser absorption spectrometers which produce harmonic absorption spectra as raw data for measuring gas mixing ratios down to parts-per-trillion levels at a variety of pressures. The methods, which take advantage of modern computer speed, memory, and data storage capabilities, are applicable to the detection of weakly absorbing gases in quantitative industrial monitoring, in addition to aircraft and balloon atmospheric measurements for which they were designed. Algorithms for calibration and data analysis, including rejection of erroneous spectra, variation of effective integration time, spectral alignment prior to averaging, and plotting and archiving of results, have been tested on actual stratospheric laser spectra recorded by the Aircraft Laser Infrared Absorption Spectrometer (ALIAS) spectrometer in numerous flights of NASA's ER-2 aircraft.

  2. FTIR-spectrometer-determined absorption coefficients of seven hydrazine fuel gases - Implications for laser remote sensing

    NASA Technical Reports Server (NTRS)

    Molina, L. T.; Grant, W. B.

    1984-01-01

    The absorption spectra of three hydrazines and four of their air-oxidation products were measured in the 9-12-micron spectral region with a Fourier transform infrared (FTIR) spectrometer with a 0.05-kayser resolution to determine absorption coefficients at CO2 and tunable diode laser wavelengths. The measurements agreed well with published CO2 laser determinations for many of the absorption coefficients, except where the published values are thought to be in error. The coefficients were then used to estimate the sensitivity for remote detection of these gases using CO2 and tunable diode lasers in long-path differential absorption measurements.

  3. 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.

  4. 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.

  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. Photoacoustic absorption spectrometer for highly transparent dielectrics with parts-per-million sensitivity

    NASA Astrophysics Data System (ADS)

    Waasem, Niklas; Fieberg, Stephan; Hauser, Janosch; Gomes, Gregory; Haertle, Daniel; Kühnemann, Frank; Buse, Karsten

    2013-02-01

    A sensitive photoacoustic absorption spectrometer for highly transparent solids has been built and tested. As the light source an optical parametrical oscillator pumped by a nanosecond pulse laser with 10 Hz repetition rate is employed, covering the complete wavelength range from 407 to 2600 nm. A second-harmonic-generation unit extends the range of accessible wavelengths down to 212 nm. A lead-zirconate-titanate piezo transducer, directly coupled to the sample, detects the photoacoustically generated sound waves. Absorption spectra of lithium triborate, lithium niobate, and alpha barium borate crystals with absorption coefficients down to 10-5 cm-1 are presented.

  8. Photoacoustic absorption spectrometer for highly transparent dielectrics with parts-per-million sensitivity.

    PubMed

    Waasem, Niklas; Fieberg, Stephan; Hauser, Janosch; Gomes, Gregory; Haertle, Daniel; Kühnemann, Frank; Buse, Karsten

    2013-02-01

    A sensitive photoacoustic absorption spectrometer for highly transparent solids has been built and tested. As the light source an optical parametrical oscillator pumped by a nanosecond pulse laser with 10 Hz repetition rate is employed, covering the complete wavelength range from 407 to 2600 nm. A second-harmonic-generation unit extends the range of accessible wavelengths down to 212 nm. A lead-zirconate-titanate piezo transducer, directly coupled to the sample, detects the photoacoustically generated sound waves. Absorption spectra of lithium triborate, lithium niobate, and alpha barium borate crystals with absorption coefficients down to 10(-5) cm(-1) are presented.

  9. 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.

  10. 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.

  11. Undersampling Correction for Array Detector-Based Satellite Spectrometers

    NASA Technical Reports Server (NTRS)

    Chance, Kelly; Kurosu, Thomas P.; Sioris, Christopher E.

    2004-01-01

    Array detector-based instruments are now fundamental to measurements of ozone and other atmospheric trace gases from space in the ultraviolet, visible, and infrared. The present generation of such instruments suffers, to a greater or lesser degree, from undersampling of the spectra, leading to difficulties in the analysis of atmospheric radiances. We provide extended analysis of the undersampling suffered by modem satellite spectrometers, which include Global Ozone Monitoring Experiment (GOME), Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY), Ozone Monitoring Instrument (OMI), and Ozone Mapping and Profiler Suite (OMPS). The analysis includes basic undersampling, the effects of binning into separate detector pixels, and the application of high-resolution Fraunhofer spectral data to correct for undersampling in many useful cases.

  12. Sensing systems using chip-based spectrometers

    NASA Astrophysics Data System (ADS)

    Nitkowski, Arthur; Preston, Kyle J.; Sherwood-Droz, Nicolás.; Behr, Bradford B.; Bismilla, Yusuf; Cenko, Andrew T.; DesRoches, Brandon; Meade, Jeffrey T.; Munro, Elizabeth A.; Slaa, Jared; Schmidt, Bradley S.; Hajian, Arsen R.

    2014-06-01

    Tornado Spectral Systems has developed a new chip-based spectrometer called OCTANE, the Optical Coherence Tomography Advanced Nanophotonic Engine, built using a planar lightwave circuit with integrated waveguides fabricated on a silicon wafer. While designed for spectral domain optical coherence tomography (SD-OCT) systems, the same miniaturized technology can be applied to many other spectroscopic applications. The field of integrated optics enables the design of complex optical systems which are monolithically integrated on silicon chips. The form factors of these systems can be significantly smaller, more robust and less expensive than their equivalent free-space counterparts. Fabrication techniques and material systems developed for microelectronics have previously been adapted for integrated optics in the telecom industry, where millions of chip-based components are used to power the optical backbone of the internet. We have further adapted the photonic technology platform for spectroscopy applications, allowing unheard-of economies of scale for these types of optical devices. Instead of changing lenses and aligning systems, these devices are accurately designed programmatically and are easily customized for specific applications. Spectrometers using integrated optics have large advantages in systems where size, robustness and cost matter: field-deployable devices, UAVs, UUVs, satellites, handheld scanning and more. We will discuss the performance characteristics of our chip-based spectrometers and the type of spectral sensing applications enabled by this technology.

  13. Characterization of a new modular decay total absorption gamma-ray spectrometer (DTAS) for FAIR

    SciTech Connect

    Montaner Piza, A.; Tain, J. L.; Agramunt, J.; Algora, A.; Guadilla, V.; Marin, E.; Rice, S.; Rubio, B.

    2013-06-10

    Beta-decay studies are one of the main goals of the DEcay SPECtroscopy experiment (DESPEC) to be installed at the future Facility for Antiproton and Ion Research (FAIR). DESPEC aims at the study of nuclear structure of exotic nuclei. A new modular Decay Total Absorption gamma-ray Spectrometer (DTAS) is being built at IFIC and is specially adapted to studies at fragmentation facilities such as the Super Fragment Separator (Super-FRS) at FAIR. The designed spectrometer is composed of 16 identical NaI(Tl) scintillation crystals. This work focuses on the characterization of these independent modules, as an initial step for the characterization of the full spectrometer. Monte Carlo simulations have been performed in order to understand the detector response.

  14. Simulations of an airborne laser absorption spectrometer for atmospheric CO2 measurements

    NASA Astrophysics Data System (ADS)

    Lin, B.; Ismail, S.; Harrison, F. W.; Browell, E. V.; Dobler, J. T.; Refaat, T.; Kooi, S. A.

    2012-12-01

    Atmospheric column amount of carbon dioxide (CO2), a major greenhouse gas of the atmosphere, has significantly increased from a preindustrial value of about 280 parts per million (ppm) to more than 390 ppm at present. Our knowledge about the spatiotemporal change and variability of the greenhouse gas, however, is limited. Thus, a near-term space mission of the Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) is crucial to increase our understanding of global sources and sinks of CO2. Currently, NASA Langley Research Center (LaRC) and ITT Exelis are jointly developing and testing an airborne laser absorption spectrometer (LAS) as a prototype instrument for the mission. To assess the space capability of accurate atmospheric CO2 measurements, accurate modeling of the instrument and practical evaluation of space applications are the keys for the success of the ASCENDS mission. This study discusses the simulations of the performance of the airborne instrument and its CO2 measurements. The LAS is a multi-wavelength spectrometer operating on a 1.57 um CO2 absorption line. The Intensity-Modulated Continuous-Wave (IM-CW) approach is implemented in the instrument. To reach accurate CO2 measurements, transmitted signals are monitored internally as reference channels. A model of this kind of instrument includes all major components of the spectrometer, such as modulation generator, fiber amplifier, telescope, detector, transimpedance amplifier, matched filter, and other signal processors. The characteristics of these components are based on actual laboratory tests, product specifications, and general understanding of the functionality of the components. For simulations of atmospheric CO2 measurements, environmental conditions related to surface reflection, atmospheric CO2 and H2O profiles, thin clouds, and aerosol layers, are introduced into the model. Furthermore, all major noise sources such as those from detectors, background radiation, speckle, and

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

    SciTech Connect

    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.

  16. JPL Carbon Dioxide Laser Absorption Spectrometer Data Processing Results for the 2010 Flight Campaign

    NASA Technical Reports Server (NTRS)

    Jacob, Joseph C.; Spiers, Gary D.; Menzie, Robert T.; Christensen, Lance E.

    2011-01-01

    As a precursor to and validation of the core technology necessary for NASA's Active Sensing of CO2 Emissions over Nights, Days,and Seasons (ASCENDS) mission, we flew JPL's Carbon Dioxide Laser Absorption Spectrometer (CO2LAS) in a campaign of five flights onboard NASA's DC-8 Airborne Laboratory in July 2010. This is the latest in a series of annual flight campaigns that began in 2006, and our first on the DC-8 aircraft.

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

    SciTech Connect

    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.

  18. A split imaging spectrometer for temporally and spatially resolved titanium absorption spectroscopy

    SciTech Connect

    Hager, J. D. Lanier, N. E.; Kline, J. L.; Flippo, K. A.; Bruns, H. C.; Schneider, M.; Saculla, M.; McCarville, T.

    2014-11-15

    We present a temporally and a spatially resolved spectrometer for titanium x-ray absorption spectroscopy along 2 axial symmetric lines-of-sight. Each line-of-sight of the instrument uses an elliptical crystal to acquire both the 2p and 3p Ti absorption lines on a single, time gated channel of the instrument. The 2 axial symmetric lines-of-sight allow the 2p and 3p absorption features to be measured through the same point in space using both channels of the instrument. The spatially dependent material temperature can be inferred by observing the 2p and the 3p Ti absorption features. The data are recorded on a two strip framing camera with each strip collecting data from a single line-of-sight. The design is compatible for use at both the OMEGA laser and the National Ignition Facility. The spectrometer is intended to measure the material temperature behind a Marshak wave in a radiatively driven SiO{sub 2} foam with a Ti foam tracer. In this configuration, a broad band CsI backlighter will be used for a source and the Ti absorption spectrum measured.

  19. 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.

  20. Development of a cavity enhanced absorption spectrometer for airborne measurements of CH4 and CO2

    NASA Astrophysics Data System (ADS)

    O'Shea, S. J.; Bauguitte, S. J.-B.; Gallagher, M. W.; Lowry, D.; Percival, C. J.

    2013-01-01

    High-resolution CH4 and CO2 measurements were made onboard the FAAM BAe 146 UK atmospheric research aircraft during a number of field campaigns. The system was based on an infrared spectrometer using the cavity enhanced absorption spectroscopy technique. Correction functions to convert the mole fractions retrieved from the spectroscopy to dry air mole fractions were derived using laboratory experiments and over a 3 month period showed good stability. Long-term performance of the system was monitored using WMO traceable calibration gases. During the first year of operation (29 flights) analysis of the system's in-flight calibrations suggest that its measurements are accurate to -0.07 ppbv (1 σ precision at 1 Hz = 2.48 ppbv) for CH4 and -0.06 ppmv (1 σ precision at 1 Hz = 0.66 ppmv) for CO2. The system was found to be very robust, no major motion or altitude dependency could be detected in the measurements. An inter-comparison between whole air samples that were analysed post-flight for CH4 and CO2 by cavity ring down spectroscopy showed a mean difference between the two techniques of -2.4 ppbv (1 σ = 2.3 ppbv) for CH4 and -0.22 ppmv (1 σ = 0.45 ppmv) for CO2. In September 2012, the system was used to sample biomass burning plumes in Brazil as part of the SAMBBA project (South American biomass burning analysis). From these and simultaneous CO measurements, emission factors for savannah fires were calculated. These were found to be 2.2 ± 0.2 g (kg dry matter)-1 for CH4 and 1710 ± 171 g (kg dry matter)-1 for CO2, which are in excellent agreement with previous estimates in the literature.

  1. 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.

  2. 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.

  3. The use of selected neutron absorption resonance filters to suppress spurious events on hot neutron spectrometers

    NASA Astrophysics Data System (ADS)

    Lançon, D.; Ewings, R. A.; Stewart, J. R.; Jiménez-Ruiz, M.; Rønnow, H. M.

    2015-04-01

    Resonant absorption can be used as a filter for high energy neutron spectroscopy. Here we report the transmission of eight thin foil filters: erbium, indium, iridium, dysprosium, hafnium, gadolinium, cadmium and samarium, measured using neutron time-of-flight techniques over a range of energies (1 meV to 10 eV). Measured transmission is converted into energy-dependent absorption cross-section which compares closely to tabulated values. Each resonance is characterized from 91 meV (samarium) to 2815 meV (gadolinium) by Lorentzian fits. Possibilities for the use of neutron filters depending on the type of spurious background are discussed and the performance is simulated for a specific example of a hot neutron triple axis spectrometer experiment.

  4. A broadband ultrafast transient absorption spectrometer covering the range from near-infrared (NIR) down to green.

    PubMed

    Schmidhammer, Uli; Jeunesse, Pierre; Stresing, Gerhard; Mostafavi, Mehran

    2014-01-01

    We present a new development for pump-probe absorption spectroscopy that allows the simultaneous measurement from the green part of the visible spectrum (510 nm) over the whole near-infrared range to >1600 nm, corresponding to 0.77-2.40 eV. The system is based on a sub-picosecond supercontinuum generated in bulk material used as a broadband probe that is dispersed with a custom-made prism spectrometer and detected by an InGaAs array with extended sensitivity to the visible. Two versions, with and without probe referencing, are implemented for operation at laser repetition rates of a few hertz and kilohertz, respectively. After presentation of the optical configuration of the spectrometer, its performance is characterized and further illustrated on two time scales, with the ultrafast radiolysis of isopropanol induced by a picosecond electron pulse and with the instantaneous response of a BK7 plate to a femtosecond light pulse. The photophysics of the dye IR-140 is resolved from the femto- to picosecond regime. Stable and easy day-to-day routine use of the spectrometer also can be achieved in non-optical laboratory surroundings. For operation in a hazardous environment, the optical probe beams can be transported to the detector unit by optical fibers.

  5. A broadband absorption spectrometer using light emitting diodes for ultrasensitive, in situ trace gas detection

    NASA Astrophysics Data System (ADS)

    Langridge, Justin M.; Ball, Stephen M.; Shillings, Alexander J. L.; Jones, Roderic L.

    2008-12-01

    A broadband absorption spectrometer has been developed for highly sensitive and target-selective in situ trace gas measurements. The instrument employs two distinct modes of operation: (i) broadband cavity enhanced absorption spectroscopy (BBCEAS) is used to quantify the concentration of gases in sample mixtures from their characteristic absorption features, and (ii) periodic measurements of the cavity mirrors' reflectivity are made using step-scan phase shift cavity ringdown spectroscopy (PSCRDS). The latter PSCRDS method provides a stand-alone alternative to the more usual method of determining mirror reflectivities by measuring BBCEAS absorption spectra for calibration samples of known composition. Moreover, the instrument's two modes of operation use light from the same light emitting diode transmitted through the cavity in the same optical alignment, hence minimizing the potential for systematic errors between mirror reflectivity determinations and concentration measurements. The ability of the instrument to quantify absorber concentrations is tested in instrument intercomparison exercises for NO2 (versus a laser broadband cavity ringdown spectrometer) and for H2O (versus a commercial hygrometer). A method is also proposed for calculating effective absorption cross sections for fitting the differential structure in BBCEAS spectra due to strong, narrow absorption lines that are under-resolved and hence exhibit non-Beer-Lambert law behavior at the resolution of the BBCEAS measurements. This approach is tested on BBCEAS spectra of water vapor's 4v+δ absorption bands around 650 nm. The most immediate analytical application of the present instrument is in quantifying the concentration of reactive trace gases in the ambient atmosphere. The instrument's detection limits for NO3 as a function of integration time are considered in detail using an Allan variance analysis. Experiments under laboratory conditions produce a 1σ detection limit of 0.25 pptv for a 10 s

  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. 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

  8. Aerosol absorption measurement at SWIR with water vapor interference using a differential photoacoustic spectrometer.

    PubMed

    Zhu, Wenyue; Liu, Qiang; Wu, Yi

    2015-09-07

    Atmospheric aerosol plays an important role in atmospheric radiation balance through absorbing and scattering the solar radiation, which changes local weather and global climate. Accurate measurement is highly requested to estimate the radiative effects and climate effects of atmospheric aerosol. Photoacoustic spectroscopy (PAS) technique, which observes the aerosols on their natural suspended state and is insensitive to light scattering, is commonly recognized as one of the best candidates to measure the optical absorption coefficient (OAC) of aerosols. In the present work, a method of measuring aerosol OAC at the wavelength where could also be absorbed by water vapor was proposed and corresponding measurements of the absorption properties of the atmospheric aerosol at the short wave infrared (SWIR, 1342 nm) wavelength were carried out. The spectrometer was made up of two high performance homemade photoacoustic cells. To improve the sensitivity, several methods were presented to control the noise derived from gas flow and vibration from the sampling pump. Calibration of the OAC and properties of the system were also studied in detail. Using the established PAS instrument, measurement of the optical absorption properties of the atmospheric aerosol were carried out in laboratory and field environment.

  9. Cavity ring-down spectrometer for high-fidelity molecular absorption measurements

    NASA Astrophysics Data System (ADS)

    Lin, H.; Reed, Z. D.; Sironneau, V. T.; Hodges, J. T.

    2015-08-01

    We present a cavity ring-down spectrometer which was developed for near-infrared measurements of laser absorption by atmospheric greenhouse gases. This system has several important attributes that make it possible to conduct broad spectral surveys and to determine line-by-line parameters with wide dynamic range, and high spectral resolution, sensitivity and accuracy. We demonstrate a noise-equivalent absorption coefficient of 4×10-12 cm-1 Hz-1/2 and a signal-to-noise ratio of 1.5×106:1 in an absorption spectrum of carbon monoxide. We also present high-resolution measurements of trace methane in air spanning more than 1.2 THz and having a frequency axing with an uncertainty less than 100 kHz. Finally, we discuss how this system enables stringent tests of advanced line shape models. To illustrate, we measured an air-broadened carbon dioxide transition over a wide pressure range and analyzed these data with a multi-spectrum fit of the partially correlated, quadratic speed-dependent Nelkin-Ghatak profile. We obtained a quality-of-fit parameter in the multispectrum fit equal to 36,000, thus quantifying small-but-measurable limitations of the model profile. This analysis showed that the line shape depends upon collisional narrowing, speed dependent effects and partial correlations between velocity- and phase-changing collisions.

  10. A simple scanning spectrometer based on a stretchable elastomeric reflective grating

    SciTech Connect

    Ghisleri, C.; Milani, P.; Potenza, M. A. C.; Bellacicca, A.; Ravagnan, L.

    2014-02-10

    We report a scanning optical spectrometer based on the use of a stretchable elastomeric reflective grating. The grating is obtained by supersonic cluster beam implantation of silver nanoparticles on polydimethylsiloxane previously grooved by molding to create a replica of a commercial digital versatile disk grating. The use of a stretchable grating allows the spectrometer spanning the whole optical wavelength range by solely extending the diffraction element by more than 100% of its original dimensions. The stretchable reflective optical grating shows excellent performances and stability upon thousands of stretching cycles. The use of this elastomeric element makes the optical layout and the mechanics of the spectrometer extremely simple and advantageous for those applications where spectral resolution is not a major requirement. As a proof of principle, we present the absorption spectrum of Rhodamine B in solution obtained by our spectrometer and compared to commercial instruments.

  11. Optimisation of external cavity parameters of a weak absorption laser spectrometer

    SciTech Connect

    Korolenko, P V; Lagunov, V V; Nikolaev, I V; Ochkin, V N; Tskhai, S N; Yatskevich, A N

    2016-03-31

    We consider some peculiar features of the optimisation procedure of external optical cavity parameters of a laser spectrometer, caused by the use of a three-beam measurement scheme and the presence of losses in the mirrors. It is found that the maximum sensitivity to the absorption of an intracavity medium can be achieved only at a certain choice of the value and the ratio of the reflection coefficients of the mirrors. For example, registration of the spectra of the methane impurity in the atmosphere shows that in accordance with the calculation model, for the same resonator Q-factor the use of an input mirror with a smaller reflection coefficient allows the measurement sensitivity to be increased by approximately two times. (laser spectroscopy)

  12. Cavity-Enhanced Near-Infrared Laser Absorption Spectrometer for the Measurement of Acetonitrile in Breath.

    PubMed

    Gianella, Michele; Ritchie, Grant A D

    2015-07-07

    Elevated concentrations of acetonitrile have been found in the exhaled breath of patients with cystic fibrosis1 and may indicate the severity of their condition or the presence of an accompanying bacterial infection of the airways. There is therefore interest in detecting acetonitrile in exhaled breath. For this purpose, a cavity-enhanced laser absorption spectrometer (λ = 1.65 μm) with a preconcentration stage was built and is described here. The spectrometer has a limit of detection of 72 ppbv and 114 ppbv of acetonitrile in nitrogen and breath, respectively, with a measurement duration of just under 5 min. The preconcentration stage, which employs a carbon molecular sieve and an adsorption/thermal desorption cycle, can increase the acetonitrile concentration by up to a factor 93, thus, lowering the overall limit of detection to approximately 1 ppbv. The suitability of the system for acetonitrile measurements in breath is demonstrated with breath samples taken from the authors, which yielded acetonitrile concentrations of 23 ± 3 ppbv and 29 ± 3 ppbv, respectively.

  13. High energy resolution five-crystal spectrometer for high quality fluorescence and absorption measurements on an x-ray absorption spectroscopy beamline

    SciTech Connect

    Llorens, Isabelle; Lahera, Eric; Delnet, William; Proux, Olivier; Dermigny, Quentin; Gelebart, Frederic; Morand, Marc; Shukla, Abhay; Bardou, Nathalie; Ulrich, Olivier; and others

    2012-06-15

    Fluorescence detection is classically achieved with a solid state detector (SSD) on x-ray absorption spectroscopy (XAS) beamlines. This kind of detection however presents some limitations related to the limited energy resolution and saturation. Crystal analyzer spectrometers (CAS) based on a Johann-type geometry have been developed to overcome these limitations. We have tested and installed such a system on the BM30B/CRG-FAME XAS beamline at the ESRF dedicated to the structural investigation of very dilute systems in environmental, material and biological sciences. The spectrometer has been designed to be a mobile device for easy integration in multi-purpose hard x-ray synchrotron beamlines or even with a laboratory x-ray source. The CAS allows to collect x-ray photons from a large solid angle with five spherically bent crystals. It will cover a large energy range allowing to probe fluorescence lines characteristic of all the elements from Ca (Z = 20) to U (Z = 92). It provides an energy resolution of 1-2 eV. XAS spectroscopy is the main application of this device even if other spectroscopic techniques (RIXS, XES, XRS, etc.) can be also achieved with it. The performances of the CAS are illustrated by two experiments that are difficult or impossible to perform with SSD and the complementarity of the CAS vs SSD detectors is discussed.

  14. An atomic-absorption spectrometer with an electrothermal atomizer in a magnetic field

    SciTech Connect

    Eristavi, V.D; Ivanov, V.K.; Sadagov, Y.M.; Sharashidze, P.A.

    1986-08-01

    This paper describes a system for correcting unselective interference. The system enables one to amplify the preparation of specimens of complicated composition, and it increases the accuracy at the expense of only a very slight sensitivity loss. The Zeeman AA spectrometer with electrothermal atomizer is shown and is based on the optical system of an S-302 AA spectrometer. The resonant-radiation sources were VSB-2 electrodeless high-frequency lamps or 1SP-1 hollow-cathode ones supplied with dc. The system for correcting for unselective interference enables one to simplify the preparation of specimens of complicated composition and it increases the accuracy at the expense of only a very slight sensitivity loss.

  15. 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

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

    SciTech Connect

    Rasco, B. C.; Fijałkowska, A.; Karny, M.; Rykaczewski, K. P.; Wolińska-Cichocka, M.; Grzywacz, R.; Goetz, K. C.

    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 detailed 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.

  17. Total Absorption Gamma-ray Spectrometer (TAGS) Intensity Distributions from INL's Gamma-Ray Spectrometry Center

    DOE Data Explorer

    Greenwood, R. E.

    A 252Cf fission-product source and the INL on-line isotope separator were used to supply isotope-separated fission-product nuclides to a total absorption -ray spectrometer. This spectrometer consisted of a large (25.4-cm diameter x 30.5-cm long) NaI(Tl) detector with a 20.3-cm deep axial well in which is placed a 300-mm2 x 1.0-mm Si detector. The spectra from the NaI(Tl) detector are collected both in the singles mode and in coincidence with the B-events detected in the Si detector. Ideally, this detector would sum all the energy of the B- rays in each cascade following the population of daughter level by B- decay, so that the event could be directly associated with a particular daughter level. However, there are losses of energy from attenuation of the rays before they reach the detector, transmission of rays through the detector, escape of secondary photons from Compton scattering, escape of rays through the detector well, internal conversion, etc., and the measured spectra are thus more complicated than the ideal case and the analysis is more complex. Analysis methods have been developed to simulate all of these processes and thus provide a direct measure of the B- intensity distribution as a function of the excitation energy in the daughter nucleus. These data yield more accurate information on the B- distribution than conventional decay-scheme studies for complex decay schemes with large decay energies, because in the latter there are generally many unobserved and observed but unplaced rays. The TAGS data have been analyzed and published [R. E. Greenwood et al., Nucl Instr. and metho. A390(1997)] for 40 fission product-nuclides to determine the B- intensity distributions. [Copied from the TAGS page at http://www.inl.gov/gammaray/spectrometry/tags.shtml]. Those values are listed on this page for quick reference.

  18. 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.

  19. A doubly curved elliptical crystal spectrometer for the study of localized x-ray absorption in hot plasmas

    SciTech Connect

    Cahill, Adam D. Hoyt, Cad L.; Pikuz, Sergei A.; Shelkovenko, Tania; Hammer, David A.

    2014-10-15

    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 emitted by the plasma under study. This is accomplished using a doubly curved mica crystal which is bent both elliptically and cylindrically. We present here the foundational work in the design and development of this spectrometer along with initial results obtained with an aluminum x-pinch as the object plasma.

  20. 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.

  1. Magnetic suspension based Fourier Transform Infrared Spectrometer mechanism (FTIS)

    NASA Astrophysics Data System (ADS)

    Köker, Ingo; Langenbach, Harald; Schmid, Manfred; Lautier, Jean-Michel

    2005-07-01

    In the frame of an ESTEC technology contract the development of a Magnetically Suspended Fourier Transform Spectrometer Mechanism (FTIS) was carried out. The aim of the development is to avoid the issues found in mechanically suspended systems and to provide an active alignment and disturbance rejection capability for spectrometer applications. In the frame of FTIS an actively controlled suspension system based on the use of magnetic bearings was defined, developed and built as a demonstration model.

  2. 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.

  3. 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.

  4. Advances in OLED/OPD-based spectrometer on-a-chip

    NASA Astrophysics Data System (ADS)

    Manna, Eeshita; Fungura, Fadzai; Shinar, Joseph; Shinar, Ruth

    2015-08-01

    We describe ongoing advances toward achieving an integrated all-organic spectrometer on a chip. To this end, 2-dimensional combinatorial arrays of microcavity (μc) organic light emitting diodes (OLEDs) with systematically varying optical cavity lengths were fabricated on a single chip by changing the thickness of different organic and/or spacer layers sandwiched between the two metal electrodes. The latter, one of which is semitransparent, form the cavity. The tunable and narrower emissions from the μcOLEDs serve as excitation sources of varying wavelength for monitoring light absorption or emission. For each wavelength, the light from the μcOLED is partially absorbed by the sample under study and the transmitted light (or the light emitted by an electronically excited sample) is detected by a photodetector (PD). To obtain a compact monitor, an organic PD (OPD) is fabricated and integrated with the μcOLED array. We show the potential of encompassing a broader wavelength range by using μcOLEDs based on different emitting layers. The OPD used to realize the first all-organic integrated spectrometer described here is based on P3HT:PCBM, though more sensitive OPDs we utilized in sensing applications are expected to improve the spectrometers' performance. The utility of this all-organic μcOLED/OPD spectrometer is shown for monitoring the absorption spectra of P3HT and Alexa Fluor 405 films. The results show excellent agreement with the absorption spectra obtained with a commercial Ocean Optics spectrometer.

  5. Resonator spectrometer for precise broadband investigations of atmospheric absorption in discrete lines and water vapor related continuum in millimeter wave range.

    PubMed

    Tretyakov, M Yu; Krupnov, A F; Koshelev, M A; Makarov, D S; Serov, E A; Parshin, V V

    2009-09-01

    The instrument and methods for measuring spectral parameters of discrete atmospheric lines and water-related continuum absorption in the millimeter wave range are described. The instrument is based on measurements of the Fabry-Pérot resonance response width using fast phase continuous scanning of the frequency-synthesized radiation. The instrument allows measurement of gas absorptions at the cavity eigenfrequencies ranging from 45 to 370 GHz with the highest to date absorption variation sensitivity of 4x10(-9) cm(-1). The use of a module of two rigidly bounded maximum identical resonators differing in length by exactly a factor of two allows accurate separation of the studied gas absorption and spectrometer baseline, in particular, the absorption by water adsorbed on the resonator elements. The module is placed in a chamber with temperature controlled between -30 and +60 degrees C, which permits investigation of temperature dependence of absorption. It is shown that systematic measurement error of discrete atmospheric line parameters does not exceed the statistical one and the achieved accuracy satisfies modern demands for the atmospheric remote sensing data retrieval. Potential systematic error arising from the neglect of the effect of water adsorption on mirror surfaces is discussed. Examples of studies of water and oxygen spectral line parameters as well as continuum absorption in wet nitrogen are given.

  6. Low temperature y-ray spectrometers based on bulk superconducting and dielectric absorber crystals

    SciTech Connect

    Netel, Harrie

    1999-11-19

    Many areas of research rely on the detection of radiation, in the form of single photons or particles. By measuring the photons or particles coming from an object a lot can be learned about the object under study. In some cases there is a simple need to know the number of photons coming from the source. In cases like this a simple counter, like a Geiger-Mueller survey meter, will suffice. In other cases one want to know the spectral distribution of the photons coming from the source. In cases like that a spectrometer is needed that can distinguish between photons with different energies, like a diffraction or transmission grating. The work presented in this thesis focused on the development of a new generation broad band spectrometer that has a high energy resolving power, combined with a high absorption efficiency for photon energies above 10 keV and up to 500 keV. The spectrometers we are developing are based on low-temperature sensors, like superconducting tunnel junctions or transition edge sensors, that are coupled to bulk absorber crystals. We use the low-temperature sensors because they can offer a significant improvement in energy resolving power, compared to conventional spectrometers. We couple the low-temperature sensors to bulk absorber crystals to increase the absorption efficiency. In this chapter I introduce different types of radiation detectors and spectrometers and areas where they are being used. I also discuss the history and motivation of low-temperature spectrometers and show some of the impressive results that have been achieved in this field over the last few years. Finally I discuss the outline of this thesis.

  7. Total ozone column distribution over peninsular Malaysia from scanning imaging absorption spectrometer for atmospheric cartography (SCIAMACHY)

    NASA Astrophysics Data System (ADS)

    Tan, K. C.; Lim, H. S.; MatJafri, M. Z.

    2012-10-01

    Increasing of atmospheric ozone concentrations have received great attention around the whole because of its characteristic, in order to degrade air quality and brings hazard to human health and ecosystems. Ozone, one of the most pollutants source and brings a variety of adverse effects on plant life and human being. Continuous monitoring on ozone concentrations at atmosphere provide information and precautions for the high ozone level, which we need to be established. Satellite observation of ozone has been identified that it can provide the precise and accurate data globally, which sensitive to the small regional biases. We present measurements from Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY) included on the European environmental satellite ENVISAT, launched on 1st of March 2002. Main objective of this study is to examine the ozone distribution over Peninsular Malaysia using SCIAMACHY level-2 of total ozone column WFMD version 1.0 with spatial resolution 1° x 1.25°. Maps of time averaged (yearly, tri-monthly) ozone was generated and analyzed over Peninsular Malaysia for the year 2003 using PCI Geomatica 10.3 image processing software. It was retrieved using the interpolation technique. The concentration changes within boundary layer at all altitude levels are equally sensitive through the SCIAMACHY nearinfrared nadir observations. Hence, we can make observation of ozone at surface source region. The results successfully identify the area with highest and lowest concentration of ozone at Peninsular Malaysia using SCIAMACHY data. Therefore, the study is suitable to examine the distribution of ozone at tropical region.

  8. 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.

  9. A Novel Experimental Setup for Determination of Atmospheric Ammonia Fluxes Using a Tunable Diode Laser Absorption Spectrometer.

    NASA Astrophysics Data System (ADS)

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

    2009-05-01

    Characterizing area-source volatilization of ammonia has presented many challenges using fast-response techniques such as eddy covariance due to the adhesive and reactive nature of NH3 within the measuring system. A series of laboratory experiments were conducted to determine the optimal setup using a tunable diode laser absorption spectrometer (TDLAS). The series of experiments were performed concomitantly between the TDLAS and a quantum cascade tunable infrared laser differential absorption spectrometer and results are presented in a companion paper. These experiments consisted of a range of standard additions (10-1000ppbv) using both perfluoroalkoxy (PFA) and polyethylene (PE) inlet tubing ranging in lengths between 3.9 and 8.9m. To address the issue of NH3 adsorption, a test using a heated (40oC) 5-m PE sample line was used in one test series. The standard NH3 additions were mixed with either pre-purified N2 or ambient room air to mimic ambient field conditions. A novel sample inlet, provided by University of Toronto and based on the design of Aerodyne Inc., was employed for the test duration. This inlet was designed to relinquish the use of a filter on the inlet, which may pose attenuation and sample flow issues. The responses to concentration changes using these various configurations demonstrated that the response to the [NH3] changes exhibited a double exponential decay. On average, the primary decay curve represented 88% of the total change in concentration and the average decay coefficient was 0.24s. However, the secondary decay coefficient was much larger (35.2s). The optimal response of the TDLAS was obtained using the shortest length of PFA tubing (3.9m) where the primary decay responses were all greater than 90% of the total change in 0.17s on average and the remaining decay occurred over a period of 0.12s. Surprisingly, the test using the heated PE tubing did not produce any discernible improvements to the instrument response. The optimal

  10. Study on spectrometer based upon volume holographic transmission grating

    NASA Astrophysics Data System (ADS)

    Huang, Zhen; Liu, Guodong; Ren, Zhong; Zeng, Lvming

    2010-10-01

    In this present paper, a spectrometer based upon axial transmissive optical structure with the volume-phase holographic (VPH) transmission grating technology is introduced. We give a physical insight for the structure and mechanism of photorefractive volume holographic gratings and theoretically analyze some important performance parameters of the spectrometer device using the coupled wave theory, which should be considered in the process of the following design for the device with volume phase holographic transmission gratings. The experimental results show, owing to its axial transmissive optical geometry and the perfect performance of the VPH transmission grating, the spectrometer based on the volume-phase holographic transmission grating has satisfactory high resolution and wavelength accuracy. It has great promise to be widely used in the future.

  11. 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

  12. Time-resolved near-edge x-ray absorption fine structure spectroscopy on photo-induced phase transitions using a tabletop soft-x-ray spectrometer

    NASA Astrophysics Data System (ADS)

    Grossmann, P.; Rajkovic, I.; Moré, R.; Norpoth, J.; Techert, S.; Jooss, C.; Mann, Klaus

    2012-05-01

    We present a table-top soft-x-ray spectrometer for the wavelength range λ = 1-5 nm based on a stable laser-driven x-ray source, making use of a gas-puff target. With this setup, optical light-pump/soft-x-ray probe near-edge x-ray absorption fine structure (NEXAFS) experiments with a temporal resolution of about 230 ps are feasible. Pump-probe NEXAFS measurements were carried out in the "water-window" region (2.28 nm-4.36 nm) on the manganite Pr0.7Ca0.3MnO3, investigating diminutive changes of the oxygen K edge that derive from an optically induced phase transition. The results show the practicability of the table-top soft-x-ray spectrometer on demanding investigations so far exclusively conducted at synchrotron radiation sources.

  13. 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.

  14. Wet/dry film thickness measurement of paint by absorption spectroscopy with acousto-optic tunable filter spectrometer

    NASA Astrophysics Data System (ADS)

    Sinha, Pranay G.; Xiong, Xiangchun; Jin, Feng; Trivedi, Sudhir; Prasad, Narashima S.

    2005-08-01

    Controlling/monitoring the thickness of applied paint in real time is important to many situations including painting ship and submarine hulls in dry docks for maintaining health of ships and submarines against the harshness of the sea, in automobile and aerospace industries, and in a variety of other industries as a control sensor that plays significant role in product quality, process control, and cost control. Insufficient thickness results to inadequate protection while overspray leads to waste and pollution of the environment. A rugged instrumentation for the real time non-contact accurate measurement of wet and dry paint film thickness measurement will be immensely valuable. As paint is applied with several layers of the same or different type, thickness of each newly sprayed wet layer is of most interest, but measurement on dry paint is also useful. In this study, we use acousto-optic tunable filter-based near infrared spectrometer to obtain the absorption spectrum of layers of paint sprayed on sand blasted steel surface and thus measure the thickness of coating under both wet and dry situations. NIR spectra are obtained from 1100 to 2300 nm on four sample of different thickness of paint up to 127 micron. Partial least squares model built with the spectra shows good correlation with standard error of prediction within ~ 0.7 micron. Results indicate that the spectra also respond to the amount of organic solvent in the wet paint and can be used to monitor the degree of dryness of the paint in real time.

  15. 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.

  16. Correlation between the Gas Temperature and the Atomization Behavior of Analyte Elements in Flame Atomic Absorption Spectrometry Estimated with a Continuum-light-source Spectrometer System

    NASA Astrophysics Data System (ADS)

    Toya, Yusuke; Itagaki, Toshiko; Wagatsuma, Kazuaki

    2016-11-01

    In flame atomic absorption spectrometry (FAAS), the gas temperature for two types of the gas compositions, which was estimated based on a two-line method by using a simultaneous multi-wavelength spectrometer, on which a line pair of ruthenium, Ru I 372.692 nm and Ru I 372.803 nm having different excitation energies, was measured at the same time. Also using the spectrometer system, the absorption signals of both iron and ruthenium, whose oxides had different thermodynamic properties: the latter oxide was decomposed much more easily than the former one, were investigated with a nitrous oxide - acetylene flame, in comparison with an air - acetylene flame. The fuel/oxidant ratio of both the flames as well as the height of the optical path was varied as an experimental parameter. The atomization behavior of iron and ruthenium, which could be deduced from a variation in their absorption signals, was considered to be dependent not only on the gas temperature but on reducing atmosphere of the flame gas, which might be attributed to reducing radicals in a fuel-excess flame consisting of nitrous oxide. In the nitrous oxide - acetylene flame, a broader optical path having a constant and higher temperature was obtained, thus contributing to formation of analyte atoms with a stable atomization efficiency and eventually to better precision in the analytical result in FAAS.

  17. [Sub-field imaging spectrometer design based on Offner structure].

    PubMed

    Wu, Cong-Jun; Yan, Chang-Xiang; Liu, Wei; Dai, Hu

    2013-08-01

    To satisfy imaging spectrometers's miniaturization, lightweight and large field requirements in space application, the current optical design of imaging spectrometer with Offner structure was analyzed, and an simple method to design imaging spectrometer with concave grating based on current ways was given. Using the method offered, the sub-field imaging spectrometer with 400 km altitude, 0.4-1.0 microm wavelength range, 5 F-number of 720 mm focal length and 4.3 degrees total field was designed. Optical fiber was used to transfer the image in telescope's focal plane to three slits arranged in the same plane so as to achieve subfield. The CCD detector with 1 024 x 1 024 and 18 microm x 18 microm was used to receive the image of the three slits after dispersing. Using ZEMAX software optimization and tolerance analysis, the system can satisfy 5 nm spectrum resolution and 5 m field resolution, and the MTF is over 0.62 with 28 lp x mm(-1). The field of the system is almost 3 times that of similar instruments used in space probe.

  18. Development of a cavity-enhanced absorption spectrometer for airborne measurements of CH4 and CO2

    NASA Astrophysics Data System (ADS)

    O'Shea, S. J.; Bauguitte, S. J.-B.; Gallagher, M. W.; Lowry, D.; Percival, C. J.

    2013-05-01

    High-resolution CH4 and CO2 measurements were made on board the FAAM BAe-146 UK (Facility for Airborne Atmospheric Measurements, British Aerospace-146) atmospheric research aircraft during a number of field campaigns. The system was based on an infrared spectrometer using the cavity-enhanced absorption spectroscopy technique. Correction functions to convert the mole fractions retrieved from the spectroscopy to dry-air mole fractions were derived using laboratory experiments and over a 3 month period showed good stability. Long-term performance of the system was monitored using WMO (World Meteorological Office) traceable calibration gases. During the first year of operation (29 flights) analysis of the system's in-flight calibrations suggest that its measurements are accurate to 1.28 ppb (1σ repeatability at 1 Hz = 2.48 ppb) for CH4 and 0.17 ppm (1σ repeatability at 1 Hz = 0.66 ppm) for CO2. The system was found to be robust, no major motion or altitude dependency could be detected in the measurements. An inter-comparison between whole-air samples that were analysed post-flight for CH4 and CO2 by cavity ring-down spectroscopy showed a mean difference between the two techniques of -2.4 ppb (1σ = 2.3 ppb) for CH4 and -0.22 ppm (1σ = 0.45 ppm) for CO2. In September 2012, the system was used to sample biomass-burning plumes in Brazil as part of the SAMBBA project (South AMerican Biomass Burning Analysis). From these and simultaneous CO measurements, emission factors for savannah fires were calculated. These were found to be 2.2 ± 0.2 g (kg dry matter)-1 for CH4 and 1710 ± 171 g (kg dry matter)-1 for CO2, which are in excellent agreement with previous estimates in the literature.

  19. 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.

  20. Airborne Laser Absorption Spectrometer Measurements of CO2 Column Mixing Ratios: Source and Sink Detection in the Atmospheric Environment

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    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. The four most recent flight campaigns were on the NASA DC-8 research aircraft, in support of the NASA ASCENDS (Active Sensing of CO2 Emissions over Nights, Days, and Seasons) mission formulation studies. This instrument operates in the 2.05-μm spectral region. The Integrated Path Differential Absorption (IPDA) method is used to retrieve weighted CO2 column mixing ratios. We present key features of the CO2LAS signal processing, data analysis, and the calibration/validation methodology. Results from flights in various U.S. locations during the past three years include observed mid-day CO2 drawdown in the Midwest, also cases of point-source and regional plume detection that enable the calculation of emission rates.

  1. Instrumentation and key elements of the dispersive x-ray absorption spectrometer for accurate measurements (invited) (abstract)

    NASA Astrophysics Data System (ADS)

    Fontaine, A.; Baudelet, F.; Dartyge, E.; Dubuisson, J. M.; Giorgetti, C.; Pizzini, Stefania; Andrault, D.; Farges, F.; Fiquet, G.; Itié, J. P.; Polian, A.; Miguel, A. San; Tolentino, H.

    1995-02-01

    Measurement of very small differences of the total cross section is the current demand for the spectrometers dedicated to time-dependent experiments carried out under various time-ramped parameters. The dispersive optics and more precisely the full x-ray-absorption spectrometer is mechanically movement-free during data collection which can last over 12 h at LURE-DCI to be sensitive to relative change of the absorption of the order of 10-5. In this range, artefacts due to the drift of silicon lattice spacing under temperature change of the crystal, and drifts of the detector position because of liquid-nitrogen evaporation contained in the cryostat, are sources of errors which have been identified and cured or ... by-passed. The accuracy in difference measurements is now of the order of 10-5 for a total cross section measured equal to 1. In term of optics stability a difference signal of 10-4 out of 1 can be generated by an absorption edge shift caused by a 0.05 K drift of the temperature of the silicon crystal at 7 keV. These performances are essential for the measurement of XMCD in the hard-x-ray range. Water cooling of the dynamically bent crystal reduces dramatically the change of the Si temperature. Adequate geometry makes the spatial drift of the position of the photodiode array much less concerning. The focusing efficiency is also a key parameter to push high-pressure x-ray-absorption spectroscopy (55 GPa), and high-temperature XAS (2000 K), and the combination (15 GPa, 800 K). Simple devices, taking advantage of the focusing geometry, have been successfully tested these last two years.

  2. 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.

  3. A Computer-based Tutorial on Double-Focusing Spectrometers

    NASA Astrophysics Data System (ADS)

    Silbar, Richard R.; Browman, Andrew A.; Mead, William C.; Williams, Robert A.

    1998-10-01

    WhistleSoft is developing a set of computer-based, self-paced tutorials on particle accelerators that targets a broad audience, including undergraduate science majors and industrial technicians. (See http://www.whistlesoft.com/s~ilbar/.) We use multimedia techniques to enhance the student's rate of learning and retention of the material. The tutorials feature interactive On-Screen Laboratories and use hypertext, colored graphics, two- and three-dimensional animations, video, and sound. Parts of our Dipoles module deal with the double-focusing spectrometer and occur throughout the piece. Radial focusing occurs in the section on uniform magnets, while vertical focusing is in the non-uniform magnets section. The student can even understand the √2π bend angle on working through the (intermediate-level) discussion on the Kerst-Serber equations. This talk will present our discussion of this spectrometer, direct to you from the computer screen.

  4. Planar prism spectrometer based on adiabatically connected waveguiding slabs

    NASA Astrophysics Data System (ADS)

    Civitci, F.; Hammer, M.; Hoekstra, H. J. W. M.

    2016-04-01

    The device principle of a prism-based on-chip spectrometer for TE polarization is introduced. The spectrometer exploits the modal dispersion in planar waveguides in a layout with slab regions having two different thicknesses of the guiding layer. The set-up uses parabolic mirrors, for the collimation of light of the input waveguide and focusing of the light to the receiver waveguides, which relies on total internal reflection at the interface between two such regions. These regions are connected adiabatically to prevent unwanted mode conversion and loss at the edges of the prism. The structure can be fabricated with two wet etching steps. The paper presents basic theory and a general approach for device optimization. The latter is illustrated with a numerical example assuming SiON technology.

  5. Atmospheric solar absorption measurements in the 9-11 micron 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 9 to 12 micron spectral range. The performance and operating characteristics of this tunable infrared heterodyne radiometer (TIHR) is discussed along with recently measured heterodyne solar absorption spectra in the 10 to 11 micron spectral region.

  6. CH4 and N2O Measurement Performance with Novel Mid-Infrared Tunable Laser Absorption Spectrometer

    NASA Astrophysics Data System (ADS)

    Wright, A. O.; Kita, D.

    2011-12-01

    Ongoing activities in the greenhouse gas (GHG) monitoring community have called for greater precision and accuracy in greenhouse gas (GHG) measurements, including CO2, CH4, and N2O. In past years this need has been served by Tunable Diode Laser Absorption Spectroscopy (TDLAS) that accesses near-infrared (NIR) single absorption transitions. We present the results of novel and commercial ready TDLAS spectrometers (the IRIS Series) utilizing mid-infrared (MIR) measurement of CH4 and N2O. Order-of-magnitude higher absorption transition strengths in the MIR compared to the NIR, combined with unique capabilities and selectivity of TDLAS, result in sub-ppb measurement noise for CH4 and N2O. The MIR laser output is generated by a small and rugged difference frequency generation (DFG) platform that uses semiconductor NIR lasers delivered fiber optically into a PPLN crystal. The spectrometer utilizes a multiple pass Herriott cell through which gas is drawn (< 0.5 LPM) by a small internal pump, with a resultant speed of response due to volumetric turnover of < 30 sec. Multiple inlet ports provide ability to sample from multiple points and/or run automated calibration routines. Optical surfaces in contact with the gas are passive and thus tolerant to aging/weathering. Data is presented for cylinder-sourced CH4 and N2O for assessing instrumental precision/variation in real time, and to independently assess the impact of ambient temperature variation on performance stability. Real ambient monitoring scenarios and results are also presented.

  7. Miniature mass spectrometer systems based on a microengineered quadrupole filter.

    PubMed

    Malcolm, Andrew; Wright, Steven; Syms, Richard R A; Dash, Neil; Schwab, Marc-André; Finlay, Alan

    2010-03-01

    Two miniature mass spectrometer systems based on a microengineered quadrupole mass filter have been developed. One of the instruments has a footprint of 27 cm x 20 cm and is intended for laboratory use when space is at a premium. The other is portable and intended for use in the field. It is battery powered, weighs 14.9 kg, and is housed in a rugged case. This is the first example of a portable mass spectrometer incorporating an analyzer fabricated using microelectromechanical systems (MEMS) techniques. The starting material for construction of the filters is a bonded silicon on insulator substrate, which is selectively etched using batch processing techniques to form coupling optics and springs that accurately hold 0.5 mm diameter stainless steel rods in the required geometry. Assembled filters measure 35 mm x 6 mm x 1.5 mm and are mounted, together with an ion source and channeltron detector, in small, interchangeable cartridges, which plug into a 220 cm(3) vacuum chamber. Recovery from accidental contamination or when servicing is required can be achieved within 5-10 min, as the cartridge is easily exchanged with a spare. A potential application to environmental monitoring has been investigated. The headspace above water spiked with dibutyl mercaptan was sampled with a solid phase microextraction (SPME) fiber, which was then injected directly into the vacuum chamber of the mass spectrometer. Using this method, the limit of detection was found to be approximately 5 ppm for a 15 s sampling period.

  8. Scattered light in a DMD based multi-object spectrometer

    NASA Astrophysics Data System (ADS)

    Fourspring, Kenneth D.; Ninkov, Zoran; Kerekes, John P.

    2010-07-01

    The DMD (Digital Micromirror Device) has an important future in both ground and space based multi-object spectrometers. A series of laboratory measurements have been performed to determine the scattered light properties of a DMD. The DMD under test had a 17 μm pitch and 1 μm gap between adjacent mirrors. Prior characterization of this device has focused on its use in DLP (TI Digital Light Processing) projector applications in which a whole pixel is illuminated by a uniform collimated source. The purpose of performing these measurements is to determine the limiting signal to noise ratio when utilizing the DMD as a slit mask in a spectrometer. The DMD pixel was determined to scatter more around the pixel edge and central via, indicating the importance of matching the telescope point spread function to the DMD. Also, the generation of DMD tested here was determined to have a significant mirror curvature. A maximum contrast ratio was determined at several wavelengths. Further measurements are underway on a newer generation DMD device, which has a smaller mirror pitch and likely different scatter characteristics. A previously constructed instrument, RITMOS (RIT Multi-Object Spectrometer) will be used to validate these scatter models and signal to noise ratio predications through imaging a star field.

  9. Diode-Laser-Based Spectrometer for Sensing Gases

    NASA Technical Reports Server (NTRS)

    Silver, Joel A.

    2005-01-01

    A diode-laser-based spectrometer has been developed for measuring concentrations of gases and is intended particularly for use in analyzing and monitoring combustion processes under microgravitational conditions in a drop tower or a spacecraft. This instrument is also well suited for use on Earth in combustion experiments and for such related purposes as fire-safety monitoring and monitoring toxic and flammable gases in industrial settings. Of the gas-sensing spectrometers available prior to the development of this instrument, those that were sensitive enough for measuring the combustion gases of interest were too large, required critical optical alignments, used far too much electrical power, and were insufficiently rugged for use under the severe conditions of spacecraft launch and space flight. In contrast, the present instrument is compact, consumes relatively little power, and is rugged enough to withstand launch vibrations and space flight. In addition, this instrument is characterized by long-term stability, accuracy, and reliability. The diode laser in this spectrometer is operated in a wavelength-modulation mode. Different gases to be measured can be selected by changing modular laser units. The operation of the laser is controlled by customized, low-power electronic circuitry built around a digital signal-processor board. This customized circuitry also performs acquisition and analysis of data, controls communications, and manages errors.

  10. 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

  11. High resolution spectrometer for extended x-ray absorption fine structure measurements in the 6 keV to 15 keV energy range

    NASA Astrophysics Data System (ADS)

    Seely, J. F.; Hudson, L. T.; Henins, Albert; Feldman, U.

    2016-11-01

    A Cauchois transmission-crystal spectrometer has been developed with high crystal resolving power in the 6 keV-15 keV energy range and sufficient sensitivity to record single-shot spectra from the Lawrence Livermore National Laboratory (LLNL) Titan laser and other comparable or more energetic lasers. The spectrometer capabilities were tested by recording the W L transitions from a laboratory source and the extended x-ray absorption fine structure (EXAFS) spectrum through a Cu foil.

  12. Mass specific optical absorption coefficients of mineral dust components measured by a multi wavelength photoacoustic spectrometer

    NASA Astrophysics Data System (ADS)

    Utry, N.; Ajtai, T.; Pintér, M.; Tombácz, E.; Illés, E.; Bozóki, Z.; Szabó, G.

    2014-09-01

    Mass specific optical absorption coefficients of various mineral dust components including silicate clays (illite, kaolin and bentonite), oxides (quartz, hematite and rutile), and carbonate (limestone) were determined at wavelengths of 1064, 532, 355 and 266 nm. These values were calculated from aerosol optical absorption coefficients measured by a multi-wavelength photoacoustic (PA) instrument, the mass concentration and the number size distribution of the generated aerosol samples as well as the size transfer functions of the measuring instruments. These results are expected to have considerable importance in global radiative forcing calculations. They can also serve as reference for validating calculated wavelength dependent imaginary parts (κ) of complex refractive indices which up to now have been typically deduced from bulk phase measurements by using indirect measurement methods. Accordingly, the presented comparison of the measured and calculated aerosol optical absorption spectra revealed the strong need for standardized sample preparation and measurement methodology in case of bulk phase measurements.

  13. Atmospheric CO2 measurements with a 2 μm airborne laser absorption spectrometer employing coherent detection.

    PubMed

    Spiers, Gary D; Menzies, Robert T; Jacob, Joseph; Christensen, Lance E; Phillips, Mark W; Choi, Yonghoon; Browell, Edward V

    2011-05-10

    We report airborne measurements of CO(2) column abundance conducted during two 2009 campaigns using a 2.05 μm laser absorption spectrometer. The two flight campaigns took place in the California Mojave desert and in Oklahoma. The integrated path differential absorption (IPDA) method is used for the CO(2) column mixing ratio retrievals. This instrument and the data analysis methodology provide insight into the capabilities of the IPDA method for both airborne measurements and future global-scale CO(2) measurements from low Earth orbit pertinent to the NASA Active Sensing of CO(2) Emissions over Nights, Days, and Seasons mission. The use of a favorable absorption line in the CO(2) 2 μm band allows the on-line frequency to be displaced two (surface pressure) half-widths from line center, providing high sensitivity to the lower tropospheric CO(2). The measurement repeatability and measurement precision are in good agreement with predicted estimates. We also report comparisons with airborne in situ measurements conducted during the Oklahoma campaign.

  14. A Weld Defects Detection System Based on a Spectrometer

    PubMed Central

    Bebiano, Daniel; Alfaro, Sadek C. A.

    2009-01-01

    Improved product quality and production methods, and decreased production costs are important objectives of industries. Welding processes are part of this goal. There are many studies about monitoring and controlling welding process. This work presents a non-intrusive on-line monitoriment system and some algorithms capable of detecting GTAW weld defects. Some experiments were made to simulate weld defects by disturbing the electric arc. The data comes from a spectrometer which captures perturbations on the electric arc by the radiation emission of chosen lines. Algorithms based on change detection methods are used to indicate the presence and localization of those defects. PMID:22574049

  15. A weld defects detection system based on a spectrometer.

    PubMed

    Bebiano, Daniel; Alfaro, Sadek C A

    2009-01-01

    Improved product quality and production methods, and decreased production costs are important objectives of industries. Welding processes are part of this goal. There are many studies about monitoring and controlling welding process. This work presents a non-intrusive on-line monitoriment system and some algorithms capable of detecting GTAW weld defects. Some experiments were made to simulate weld defects by disturbing the electric arc. The data comes from a spectrometer which captures perturbations on the electric arc by the radiation emission of chosen lines. Algorithms based on change detection methods are used to indicate the presence and localization of those defects.

  16. 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.

  17. 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.

  18. Performance Of A Laser Based CO2 Isotope Ratio Infrared Spectrometer To Study Biosphere-Atmosphere Exchange

    NASA Astrophysics Data System (ADS)

    Jost, Hans-Juerg; Wapelhorst, Eric; Schlueter, Hans-Juergen; Kracht, Oliver; Radke, Jens; Hilkert, Andreas; Gangi, Laura; Bol, Roland; Brueggemann, Nicolas; Van Leeuwen, Charlotte; Meijer, Harro

    2014-05-01

    We are presenting results from a mid-infrared laser-based Isotope Ratio Infrared Spectrometers (IRIS) that is capable of simultaneously determining both δ18O and δ13C isotope ratios of carbon dioxide utilizing a simple, direct absorption approach with a robust multi pass cell and a cryogen free setup. A simulation of ambient measurement conditions with a 75 ppm per hour change in CO2 concentration from 350-650 ppm showed a precision of

  19. Direct determination of cadmium and copper in seawater using a transversely heated graphite furnace atomic absorption spectrometer with Zeeman-effect background corrector.

    PubMed

    Chan, M S; Huang, S D

    2000-02-07

    Methods for the direct determination of copper and cadmium in seawater were described using a graphite furnace atomic absorption spectrometer (GFAAS) equipped with a transversely heated graphite atomizer (THGA) and a longitudinal Zeeman effect background corrector. Ammonium nitrate was used as the chemical modifier to determine copper. The mixture of di-ammonium hydrogen phosphate and ammonium nitrate was used as the chemical modifier to determine cadmium. The matrix interference was removed completely so that a simple calibration curve method could be applied. This work is the first one with the capability of determining cadmium in unpolluted seawater directly with GFAAS using calibration curve based on simple aqueous standards. The accuracy of the methods was confirmed by analysis of three kinds of certified reference saline waters. The detection limits (LODs), with injection of a 20-mul aliquot of seawater sample, were 0.06 mug l(-1) for copper and 0.005 mug l(-1) for cadmium.

  20. Measurement of acetaldehyde in exhaled breath using a laser absorption spectrometer

    NASA Astrophysics Data System (ADS)

    Kamat, Pratyuma C.; Roller, Chad B.; Namjou, Khosrow; Jeffers, James D.; Faramarzalian, Ali; Salas, Rodolfo; McCann, Patrick J.

    2007-07-01

    A high-resolution liquid-nitrogen-free mid-infrared tunable diode laser absorption spectroscopy (TDLAS) system was used to perform real-time measurement of acetaldehyde concentrations in human exhaled breath following ingestion of an alcoholic beverage. Acetaldehyde absorption features were measured near 5.79 μm (1727 cm-1) using a IV-VI semiconductor laser, a 100 m long path optical gas cell, and second- harmonic detection coupled with wavelength modulation. Acetaldehyde levels were measured with a minimum detection limit of 80 ppb for 5 s integration time. The variations in exhaled acetaldehyde levels over time were analyzed prior to and following ingestion of two different amounts of white wine. A method to calibrate acetaldehyde measurements internally using water vapor absorption lines was investigated to eliminate the need for system calibration with gas standards. The potential of a TDLAS system to be used as a noninvasive clinical tool for measurements of large volatile compounds with possible applications in cancer detection is demonstrated.

  1. 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.

  2. Nanofibrous membrane-based absorption refrigeration system

    SciTech Connect

    Isfahani, RN; Sampath, K; Moghaddam, S

    2013-12-01

    This paper presents a study on the efficacy of highly porous nanofibrous membranes for application in membrane-based absorbers and desorbers. Permeability studies showed that membranes with a pore size greater than about one micron have a sufficient permeability for application in the absorber heat exchanger. Membranes with smaller pores were found to be adequate for the desorber heat exchanger. The membranes were implemented in experimental membrane-based absorber and desorber modules and successfully tested. Parametric studies were conducted on both absorber and desorber processes. Studies on the absorption process were focused on the effects of water vapor pressure, cooling water temperature, and the solution velocity on the absorption rate. Desorption studies were conducted on the effects of wall temperature, vapor and solution pressures, and the solution velocity on the desorption rate. Significantly higher absorption and desorption rates than in the falling film absorbers and desorbers were achieved. Published by Elsevier Ltd.

  3. Light absorption coefficient measurement of SOA using a UV-Visible spectrometer connected with an integrating sphere

    NASA Astrophysics Data System (ADS)

    Zhong, Min; Jang, Myoseon

    2011-08-01

    A method for measuring an aerosol light absorption coefficient ( B a) has been developed using a conventional UV-visible spectrometer equipped with an integrating sphere covering a wide range of wavelengths (280-800 nm). The feasibility of the proposed method was evaluated in both the transmittance mode (TUV-IS) and the reflective mode (RUV-IS) using the reference aerosol known for the cross-sectional area. The aerosol was collected on a conventional filter and measured for B a values. The resulting RUV-IS method was applied to measure light absorption of secondary organic aerosol (SOA). SOA was produced through photooxidation of different precursor hydrocarbons such as toluene, d-limonene and α-pinene in the presence of NO x (60-70 ppb) and inorganic seed aerosol using a 2-m 3 indoor Teflon film chamber. Of the three precursor hydrocarbons, the B a value of toluene SOA (0.574 m 2 g -1 at 350 nm) was the highest compared with B a values for α-pinene SOA (0.029 m 2 g -1) and d-limonene SOA (0.038 m 2 g -1). When d-limonene SOA or toluene SOA was internally mixed with neutral [(NH 4) 2SO 4] or acidic inorganic seed (NH 4HSO 4:H 2SO 4 = 1:1 by mole), the SOA showed 2-3 times greater B a values at 350 nm than the SOA with no seed. Aerosol aging with a light source for this study reduced B a values of SOA (e.g., on average 10% for toluene SOA and 30% for d-limonene SOA within 4 h). Overall, weak absorption appeared for chamber-generated SOA over wavelengths ranging from 280 to 550 nm, which fall into the sunlight spectrum.

  4. 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.

  5. Spatial heterodyne spectrometer based on the Mach-Zehnder interferometer

    NASA Astrophysics Data System (ADS)

    Cai, Qisheng; Xiangli, Bin; Du, Shusong

    2015-11-01

    Spatial heterodyne spectroscopy (SHS) is a new kind of Fourier-transform spectroscopic technique capable of very high spectral resolution. In this paper, a spatial heterodyne spectrometer based on the Mach-Zehnder interferometer (MZ-SHS) is proposed. It is modified by replacing one mirror in the Mach-Zehnder interferometer with a diffraction grating. This technique retains many of the advantages of traditional SHS. Moreover, the spatial frequency of the interferogram is strictly linear with wavenumber. We describe the concept of the new MZ-SHS and elaborate the exact expression of the interferogram. Also, a design example and two kinds of imitated interferograms are presented in this paper. One is simulated in MATLAB and the other is generated in ZEMAX using ray tracing method. The retrieved spectra from these two interferograms show a good agreement with the theoretical results.

  6. A novel electrospray-based ion mobility spectrometer

    NASA Astrophysics Data System (ADS)

    Bathgate, Ben; Cheong, Eric C. S.; Backhouse, Christopher J.

    2004-08-01

    We present a design for a low-cost ion mobility spectrometer that can be built using the equipment on hand in many electronics-oriented undergraduate laboratories. The construction of this system is based upon the use of printed circuit boards and does not require the specialized drift and sheath gases, vacuum pumps, heater assemblies, high voltage pulsers, or precision pumps that are characteristic of the systems generally reported in the literature. We demonstrate the system in the separation of ions of methanol and water in air. Despite the low cost of this system it has a performance comparable to more complex systems, with a sensitivity of approximately 100 ppm for the protein cytochrome c. This system is suitable for use as an electronics or signal-processing project, or even a biotechnology demonstration.

  7. Spectrometers for particle measurements in space based on surface reflection

    NASA Astrophysics Data System (ADS)

    Barabash, S.; Wieser, M.; Wurz, P.

    2012-04-01

    This is a review talk on space particle spectrometers based on the surface reflection technique. We sum up the experience in development and operation of such instruments accumulated for the last 15 years at the Swedish Institute of space Physics, Kiruna, Sweden in close cooperation with University of Bern, Bern, Switzerland. The technique is relatively new and used in space for measurements of few eV - few keV particles. It was first introduced for neutral atom detection in the GAS instrument onboard the ESA/NASA Ulysses mission (Witte et al., 1992) and later for ion measurements (Barabash et al., 2007) onboard Indian Chandrayaan-1. When a particle hit a surface, secondary electrons release and the particle is either absorbed by the surface or get scattered or reflected. The charge state of the reflected particles normally does not depend on the initial charge state and is neutral but also includes a fraction of negative and positive ions. These charged particles can be analyzed by conventional ion optics. The secondary electrons can be used for triggering a time-of-flight system. The surface reflection technique is close to the usage of foils/ulta-thin foils for particle detections but has a number of advantages. First, it does not require high pre-acceleration potentials and thus allows making more compact and light weight instruments. Secondly, it permits detection of neutral atoms down to 10 eV. Despite the interaction with the surface modifies the original particle velocity, the proper design of the following analyzer section and ion optics can mitigate this effect. We shortly introduce main characteristics of the particle - surface interactions important for this application, describe designs of the instruments flown in space, and show performances of the surface reflection based ENA and ion spectrometers developed for Mars / Venus Express, Chandrayaan-1, BepiColombo, Phobos-Grunt, and Swedish PRISMA.

  8. Camping Burner-Based Flame Emission Spectrometer for Classroom Demonstrations

    ERIC Educational Resources Information Center

    Ne´el, Bastien; Crespo, Gasto´n A.; Perret, Didier; Cherubini, Thomas; Bakker, Eric

    2014-01-01

    A flame emission spectrometer was built in-house for the purpose of introducing this analytical technique to students at the high school level. The aqueous sample is sprayed through a homemade nebulizer into the air inlet of a consumer-grade propane camping burner. The resulting flame is analyzed by a commercial array spectrometer for the visible…

  9. A revised thermospheric model based on mass spectrometer and incoherent scatter data - MSIS-83

    NASA Technical Reports Server (NTRS)

    Hedin, A. E.

    1983-01-01

    It is noted that the model presented here extends the previous description of neutral parameters to the base of the thermosphere in a continuous manner while maintaining the basic structure of the MSIS model at higher altitudes. As the altitude decreases, the composition approaches lower atmosphere values, whereas yearly, and to a lesser extent daily, variations in temperature and density are in reasonable agreement with earlier results for the lower thermosphere. An alternate description is given of magnetic storm variations on the basis of the three hour ap indices and an 8- to 10-hour exponential decay in thermospheric density and temperature response after a heating event. Additional coefficients are included for the time independent and magnetic activity terms, among them a longitudinally dependent seasonal magnetic activity effect. The description of molecular oxygen derives from mass spectrometer and EUV absorption measurements rather than ion chemistry.

  10. A capillary absorption spectrometer for stable carbon isotope ratio (13C/12C) analysis in very small samples

    NASA Astrophysics Data System (ADS)

    Kelly, J. F.; Sams, R. L.; Blake, T. A.; Newburn, M.; Moran, J.; Alexander, M. L.; Kreuzer, H.

    2012-02-01

    A capillary absorption spectrometer (CAS) suitable for IR laser isotope analysis of small CO2 samples is presented. The system employs a continuous-wave (cw) quantum cascade laser to study nearly adjacent rovibrational transitions of different isotopologues of CO2 near 2307 cm-1 (4.34 μm). This initial CAS system can achieve relative isotopic precision of about 10 ppm 13C, or ˜1‰ (per mil in delta notation relative to Vienna Pee Dee Belemnite) with 20-100 picomoles of entrained sample within the hollow waveguide for CO2 concentrations ˜400-750 ppm. Isotopic analyses of such gas fills in a 1-mm ID hollow waveguide of 0.8 m overall physical path length can be carried out down to ˜2 Torr. Overall 13C/12C ratios can be calibrated to ˜2‰ accuracy with diluted CO2 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 1000 scans are co-added in ˜10 s. The CAS is meant to work directly with converted CO2 samples from a laser ablation-catalytic combustion micro-sampler to provide 13C/12C ratios of small biological isolates currently operating with spatial resolutions ˜50 μm.

  11. MMI based Electro-Absorption Modulator Design

    NASA Astrophysics Data System (ADS)

    Sala, A.; Sikorski, Y.

    2007-05-01

    Electro-Absorption Modulators (EAM) are among the most important components of high-speed WDM optical communications devices and systems. During the last decade, multiple EAM designs were proposed and fabricated as stand alone devices, as part of Electro-Absorption Modulated Lasers (EML), and as part of multi component Planar Lightguide Circuits (PLC). Vast majority of all designed and fabricated EAMs employ a straight section of single mode waveguide. In this work, we present a new approach for EAM design which is based on the use of 1*1 Multimode Interference structure (MMI). We demonstrate improvements in the extinction ratio of the EAM based on a combination of electro-absorption and optical interference effects in the MMI structure. The increase in extinction ratio is not accompanied by an increase in insertion loss or chirp, nor does it lead to higher drive voltage or lower bandwidth. The MMI based EAM devices can be easily fabricated using current InP based fabrication technologies and, in-fact, allow for less stringent tolerance requirements than currently used for traditional EAM devices. To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2007.OSS07.P1.4

  12. ASIC for SDD-Based X-ray Spectrometers

    SciTech Connect

    De Geronimo, G.; Fried, J.; Rehak, P.; Ackley, K.; Carini, G.; Chen, W.; Keister, J.; Li, S.; Li, Z.; Pinelli, D.A.; Siddons, D.P.; Vernon, E.; Gaskin, J.A.; Ramsey, B.D.; Tyson, T.A.

    2010-06-16

    We present an application-specific integrated circuit (ASIC) for high-resolution x-ray spectrometers (XRS). The ASIC reads out signals from pixelated silicon drift detectors (SDDs). The pixel does not have an integrated field effect transistor (FET); rather, readout is accomplished by wire-bonding the anodes to the inputs of the ASIC. The ASIC dissipates 32 mW, and offers 16 channels of low-noise charge amplification, high-order shaping with baseline stabilization, discrimination, a novel pile-up rejector, and peak detection with an analog memory. The readout is sparse and based on custom low-power tristatable low-voltage differential signaling (LPT-LVDS). A unit of 64 SDD pixels, read out by four ASICs, covers an area of 12.8 cm{sup 2} and dissipates with the sensor biased about 15 mW/cm{sup 2}. As a tile-based system, the 64-pixel units cover a large detection area. Our preliminary measurements at -44 C show a FWHM of 145 eV at the 5.9 keV peak of a {sup 55}Fe source, and less than 80 eV on a test-pulse line at 200 eV.

  13. ASIC for SDD-Based X-Ray Spectrometers

    SciTech Connect

    G De Geronimo; P Rehak; K Ackley; G Carini; W Chen; J Fried; J Keister; S Li; Z Li; et al.

    2011-12-31

    We present an application-specific integrated circuit (ASIC) for high-resolution x-ray spectrometers (XRS). The ASIC reads out signals from pixelated silicon drift detectors (SDDs). The pixel does not have an integrated field effect transistor (FET); rather, readout is accomplished by wire-bonding the anodes to the inputs of the ASIC. The ASIC dissipates 32 mW, and offers 16 channels of low-noise charge amplification, high-order shaping with baseline stabilization, discrimination, a novel pile-up rejector, and peak detection with an analog memory. The readout is sparse and based on custom low-power tristatable low-voltage differential signaling (LPT-LVDS). A unit of 64 SDD pixels, read out by four ASICs, covers an area of 12.8 cm{sup 2} and dissipates with the sensor biased about 15 mW/cm{sup 2}. As a tile-based system, the 64-pixel units cover a large detection area. Our preliminary measurements at -44 C show a FWHM of 145 eV at the 5.9 keV peak of a {sup 55}Fe source, and less than 80 eV on a test-pulse line at 200 eV.

  14. Spatial mapping of greenhouse gases using laser absorption spectrometers at local scales of interest

    NASA Astrophysics Data System (ADS)

    Dobler, Jeremy; Zaccheo, T. S.; Blume, Nathan; Braun, Michael; Botos, Chris; Pernini, Timothy G.

    2015-10-01

    Over the past two years a new system capable of measuring the 2-D spatial distribution of atmospheric CO2 over areas on the order of 1 km2 and time scales of a few minutes, has been developed and demonstrated. The Greenhouse gas Laser Imaging Tomography Experiment (GreenLITE) - developed under a cooperative agreement with the National Energy Technology Laboratory (NETL) of the U.S. Department of Energy (DOE) - attempts to improve monitoring capabilities of Ground Carbon Storage (GCS) sites. GreenLITE sensors are based on an intensity modulated continuous wave (IM-CW) approach developed at ITT (now part of Harris Corp.) in 2004. The GreenLITE system recently completed a remote deployment of nearly 4,000 hours at a GCS site in Illinois. It provided continuous, real-time spatial distribution maps of CO2 via an open web-based interface from February to August 2015. In early 2015 we began work on a new implementation of GreenLITE capable of providing similar measurements over a 25 km2 area and are planning to test the system over a 5 km range late summer 2015. If successful the system will be deployed in an urban environment late 2015, demonstrating the utility of real-time 2-D spatial mapping of CO2 concentrations at this scale. This paper will review the concept for this new measurement capability, including results from the 1 km system. Ultimately, the measurement concept can be adapted to other greenhouse gases such as CH4 and NO2.

  15. OPENCORE NMR: open-source core modules for implementing an integrated FPGA-based NMR spectrometer.

    PubMed

    Takeda, Kazuyuki

    2008-06-01

    A tool kit for implementing an integrated FPGA-based NMR spectrometer [K. Takeda, A highly integrated FPGA-based nuclear magnetic resonance spectrometer, Rev. Sci. Instrum. 78 (2007) 033103], referred to as the OPENCORE NMR spectrometer, is open to public. The system is composed of an FPGA chip and several peripheral boards for USB communication, direct-digital synthesis (DDS), RF transmission, signal acquisition, etc. Inside the FPGA chip have been implemented a number of digital modules including three pulse programmers, the digital part of DDS, a digital quadrature demodulator, dual digital low-pass filters, and a PC interface. These FPGA core modules are written in VHDL, and their source codes are available on our website. This work aims at providing sufficient information with which one can, given some facility in circuit board manufacturing, reproduce the OPENCORE NMR spectrometer presented here. Also, the users are encouraged to modify the design of spectrometer according to their own specific needs. A home-built NMR spectrometer can serve complementary roles to a sophisticated commercial spectrometer, should one comes across such new ideas that require heavy modification to hardware inside the spectrometer. This work can lower the barrier of building a handmade NMR spectrometer in the laboratory, and promote novel and exciting NMR experiments.

  16. OPENCORE NMR: Open-source core modules for implementing an integrated FPGA-based NMR spectrometer

    NASA Astrophysics Data System (ADS)

    Takeda, Kazuyuki

    2008-06-01

    A tool kit for implementing an integrated FPGA-based NMR spectrometer [K. Takeda, A highly integrated FPGA-based nuclear magnetic resonance spectrometer, Rev. Sci. Instrum. 78 (2007) 033103], referred to as the OPENCORE NMR spectrometer, is open to public. The system is composed of an FPGA chip and several peripheral boards for USB communication, direct-digital synthesis (DDS), RF transmission, signal acquisition, etc. Inside the FPGA chip have been implemented a number of digital modules including three pulse programmers, the digital part of DDS, a digital quadrature demodulator, dual digital low-pass filters, and a PC interface. These FPGA core modules are written in VHDL, and their source codes are available on our website. This work aims at providing sufficient information with which one can, given some facility in circuit board manufacturing, reproduce the OPENCORE NMR spectrometer presented here. Also, the users are encouraged to modify the design of spectrometer according to their own specific needs. A home-built NMR spectrometer can serve complementary roles to a sophisticated commercial spectrometer, should one comes across such new ideas that require heavy modification to hardware inside the spectrometer. This work can lower the barrier of building a handmade NMR spectrometer in the laboratory, and promote novel and exciting NMR experiments.

  17. Initial investigation of the wavelength dependence of optical properties measured with a new multi-pass Aerosol Extinction Differential Optical Absorption Spectrometer (AE-DOAS)

    NASA Astrophysics Data System (ADS)

    Chartier, R. T.; Greenslade, M. E.

    2012-04-01

    Atmospheric aerosols directly affect climate by scattering and absorbing radiation. The magnitude of the impact is dependent upon the wavelength of light, but is often estimated near 550 nm. When light scattering and absorption by aerosols is approximated, the wavelength dependence of the refractive index for specific components is lost. As a result, climate models would have inherent uncertainties for aerosol contributions to radiative forcing when considering the entire solar spectrum. An aerosol extinction differential optical absorption spectrometer has been developed to directly measure aerosol extinction at mid-ultraviolet to near infrared wavelengths. The instrument consists of a spectrometer coupled to a closed White-type multi-pass gas cell with an adjustable path length of up to approximately 20 m. Laboratory measurements of various gases are compared with known absorption cross sections. Additionally, the extinction of monodisperse samples of polystyrene latex spheres are measured and compared to Mie theory generated with refractive index values from the literature to validate the new instrument. The polystyrene experiments also emphasize the ability of the new instrument to retrieve the wavelength dependent refractive index, especially in the ultraviolet wavelength regions where variability is expected. The spectrometer will be a significant advancement for determining wavelength dependent complex refractive indices in future laboratory studies as well as provide the ability to monitor ambient aerosol light extinction.

  18. Initial investigation of the wavelength dependence of optical properties measured with a new multi-pass aerosol extinction differential optical absorption spectrometer (AE-DOAS)

    NASA Astrophysics Data System (ADS)

    Chartier, R. T.; Greenslade, M. E.

    2011-10-01

    Atmospheric aerosols directly affect climate by scattering and absorbing radiation. The magnitude of the impact is dependent upon the wavelength of light, but is often estimated near 550 nm. When light scattering and absorption by aerosols is approximated, the wavelength dependence of the refractive index for specific components is lost. As a result, climate models would have inherent uncertainties for aerosol contributions to radiative forcing when considering the entire solar spectrum. An aerosol extinction differential optical absorption spectrometer has been developed to directly measure aerosol extinction at mid-ultraviolet to near infrared wavelengths. The instrument consists of a spectrometer coupled to a closed White-type multi-pass gas cell with an adjustable path length of up to approximately 20 m. Laboratory measurements of various gases are compared with known absorption cross sections. Additionally, the extinction of monodisperse samples of polystyrene latex spheres are measured and compared to Mie theory generated with refractive index values from the literature to validate the new instrument. The polystyrene experiments also emphasize the ability of the new instrument to retrieve the wavelength dependent refractive index, especially in the ultraviolet wavelength regions where variability is expected. The spectrometer will be a significant advancement for determining wavelength dependent complex refractive indices in future laboratory studies as well as provide the ability to monitor ambient aerosol light extinction.

  19. [The X-Ray Fluorescence Spectrometer Based on Pyroelectric Effect].

    PubMed

    Dong, Yi-fan; Fan, Rui-rui; Guo, Dong-ya; Zhang, Chun-lei; Gao, Min; Wang, Jin-zhou; Liu, Ya-qing; Zhou, Da-wei; Wang, Huan-yu

    2016-02-01

    Pyroelectric X-ray generator is implemented, and an X-ray fluorescence spectrometer is accomplished by combining the pyroelectric X-ray generator with a high energy resolution silicon drift detector. Firstly, the parameters of the X-ray generator are decided by analyzing and calculating the influence of the thickness of the pyroelectriccrystal and the thickness of the target on emitted X-ray. Secondly, the emitted X-ray is measured. The energy of emitted X-ray is from 1 to 27 keV, containing the characteristic X-ray of Cu and Ta, and the max counting rate is more than 3 000 per second. The measurement also proves that the detector of the spectrometer has a high energy resolution which the FWMH is 210 eV at 8. 05 keV. Lastly, samples of Fe, Ti, Cr and high-Ti basalt are analyzed using the spectrometer, and the results are agreed with the elements of the samples. It shows that the spectrometer consisting of a pyroelectric X-ray generator and a silicon drift detector is effective for element analysis. Additionally, because each part of the spectrometer has a small volume, it can be easily modified to a portable one which is suitable for non-destructive, on-site and quick element analysis.

  20. [Spectral calibration of hyperspectral imager based on spectral absorption target].

    PubMed

    Gou, Zhi-Yang; Yan, Lei; Chen, Wei; Zhao, Hong-Ying; Yin, Zhong-Yi; Duan, Yi-Ni

    2013-02-01

    Retrieval of center wavelength and bandwidth is a key step for quantitative analysis of hyperspectral data. The present paper proposes a spectral calibration method of hyperspectral imager, whose spectrum covers visible and near-infrared band, using spectral absorption target. Ground calibration experiment was designed for a hyperspectral imager with a bandwidth of 6 nm. Hyperspectral imager and ASD spectrometer measured the same spectral absorption target synchronously. Reflectance spectrum was derived from the different data set. Center wavelength and bandwidth were retrieved by matching the reflectance data from hyperspectral imager and ASD spectrometer. The experiment result shows that this method can be applied in spectral calibration of hyperspectral imagers to improve the quantitative studies on hyperspectral imagery.

  1. Dedicated spectrometers based on diffractive optics: design, modelling and evaluation

    NASA Astrophysics Data System (ADS)

    Løvhaugen, O.; Johansen, I.-R.; Bakke, K. A. H.; Fismen, B. G.; Nicolas, S.

    The described design of diffractive optical elements for low cost IR-spectrometers gives a built-in wavelength reference and allows 'spectral arithmetic' to be implemented in the optical performance of the DOE. The diffractive element combines the function of the lenses and the grating and eliminates the need for alignment of those components in the standard scanned grating spectrometer design. The element gives out a set of foci, each with one spectral component, which are scanned across a detector, thus relaxing the demands for scan angle control. It can thus be regarded as an alternative solution to a beam splitter and band pass filter instrument. Software tools have been designed to ease the adaptation of the design to different applications. To model the performance of the spectrometers we have implemented a scalar Rayleigh-Sommerfeldt diffraction model. The gold-coated elements are produced by injection moulding using a compact disc (CD) moulding technique and mould inlays mastered by e-beam lithography. The optimized selection of wavelength bands and the classification of the measured signal use a combination of principal component analysis and robust statistical methods. Typical applications will be material characterization of recycled plastics and gas monitoring. Spectrometers for two different applications have been built and tested. Comparisons between the design goals and the measured performance have been made and show good agreements.

  2. Design of FUV imaging spectrometer based on crossed Czerny-Turner structure

    NASA Astrophysics Data System (ADS)

    Wu, Yan; Tang, Yi; Ni, Guoqiang

    2008-12-01

    This article describes the characteristics of the far ultraviolet (FUV) radiation and its applications in the space weather's research and prediction. The FUV imaging spectrometer is irreplaceable to get the FUV radiation data of the earth's upper atmosphere. Some key technologies of FUV spectrometer are analyzed respectively, including window materials, FUV light source, FUV detectors and FUV coating, which offer theoretical foundation for FUV imaging spectrometer. The paper presents a FUV band imaging spectrometer's optical system which is based on crossed Czerny-Turner structure with all reflective components in it. The wavelength range of the FUV spectrometer optical system is from 100nm to 200nm and the initial structure is simulated and optimized by Zemax in order to improve the spectral resolution. The theoretical spectral resolution of the system is better than 1nm, and it has a certain imaging capacity.

  3. 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

  4. [Optical Design of Miniature Infrared Gratings Spectrometer Based on Planar Waveguide].

    PubMed

    Li, Yang-yu; Fang, Yong-hua; Li, Da-cheng; Liu, Yang

    2015-03-01

    In order to miniaturize an infrared spectrometer, we analyze the current optical design of miniature spectrometers and propose a method for designing a miniature infrared gratings spectrometer based on planar waveguide. Common miniature spectrometer uses miniature optical elements to reduce the size of system, which also shrinks the effective aperture. So the performance of spectrometer has dropped. Miniaturization principle of planar waveguide spectrometer is different from the principle of common miniature spectrometer. In planar waveguide spectrometer, the propagation of light is limited in a thin planar waveguide, which looks like the whole optical system is squashed flat. In the direction parallel to the planar waveguide, the light through the slit is collimated, dispersed and focused. And a spectral image is formed in the detector plane. This propagation of light is similar to the light in common miniature spectrometer. In the direction perpendicular to the planar waveguide, light is multiple reflected by the upper and lower surfaces of the planar waveguide and propagates in the waveguide. So the size of corresponding optical element could be very small in the vertical direction, which can reduce the size of the optical system. And the performance of the spectrometer is still good. The design method of the planar waveguide spectrometer can be separated into two parts, Czerny-Turner structure design and planar waveguide structure design. First, by using aberration theory an aberration-corrected (spherical aberration, coma, focal curve) Czerny-Turner structure is obtained. The operation wavelength range and spectral resolution are also fixed. Then, by using geometrical optics theory a planar waveguide structure is designed for reducing the system size and correcting the astigmatism. The planar waveguide structure includes a planar waveguide and two cylindrical lenses. Finally, they are modeled together in optical design software and are optimized as a whole. An

  5. Two-channel opto-acoustic diode laser spectrometer and fine structure of methane absorption spectra in 6070-6180 cm-1 region.

    PubMed

    Kapitanov, V A; Ponomarev, Yu N; Tyryshkin, I S; Rostov, A P

    2007-04-01

    We describe the hardware and software of the high-sensitive two-channel opto-acoustic spectrometer with a near infrared diode laser. A semiconductor TEC-100 laser with outer resonator generates a continuous single-frequency radiation in the range of 6040-6300 cm-1 with spectral resolution better that 10 MHz. The newly designed model of photo-acoustic cells in the form of a ring type resonator was used in the spectrometer, and the system allows the measurement of a weak absorption coefficient equal to 1.4x10(-7) cm-1 Hz-1/2 with a laser radiation power of 0.003 W. The methane absorption spectra within a range of 6080-6180 cm-1 were measured with a spectral resolution of 10 MHz and the signal to noise ratio more than 10(3). Six hundred absorption lines were recorded, which is twice as many as in HITRAN-2004. The accurate measurements of the half-width and shift of methane unresolved triplet R3 of 2nu3 band permit us to determine values of the broadening and shift coefficients for CH4-air, CH4-N2, and CH4-SF6 mixtures.

  6. DLP NIRscan Nano: an ultra-mobile DLP-based near-infrared Bluetooth spectrometer

    NASA Astrophysics Data System (ADS)

    Gelabert, Pedro; Pruett, Eric; Perrella, Gavin; Subramanian, Sreeram; Lakshminarayanan, Aravind

    2016-02-01

    The DLP NIRscan Nano is an ultra-portable spectrometer evaluation module utilizing DLP technology to meet lower cost, smaller size, and higher performance than traditional architectures. The replacement of a linear array detector with DLP digital micromirror device (DMD) in conjunction with a single point detector adds the functionality of programmable spectral filters and sampling techniques that were not previously available on NIR spectrometers. This paper presents the hardware, software, and optical systems of the DLP NIRscan Nano and its design considerations on the implementation of a DLP-based spectrometer.

  7. Research of aerial imaging spectrometer data acquisition technology based on USB 3.0

    NASA Astrophysics Data System (ADS)

    Huang, Junze; Wang, Yueming; He, Daogang; Yu, Yanan

    2016-11-01

    With the emergence of UAV (unmanned aerial vehicle) platform for aerial imaging spectrometer, research of aerial imaging spectrometer DAS(data acquisition system) faces new challenges. Due to the limitation of platform and other factors, the aerial imaging spectrometer DAS requires small-light, low-cost and universal. Traditional aerial imaging spectrometer DAS system is expensive, bulky, non-universal and unsupported plug-and-play based on PCIe. So that has been unable to meet promotion and application of the aerial imaging spectrometer. In order to solve these problems, the new data acquisition scheme bases on USB3.0 interface.USB3.0 can provide guarantee of small-light, low-cost and universal relying on the forward-looking technology advantage. USB3.0 transmission theory is up to 5Gbps.And the GPIF programming interface achieves 3.2Gbps of the effective theoretical data bandwidth.USB3.0 can fully meet the needs of the aerial imaging spectrometer data transmission rate. The scheme uses the slave FIFO asynchronous data transmission mode between FPGA and USB3014 interface chip. Firstly system collects spectral data from TLK2711 of high-speed serial interface chip. Then FPGA receives data in DDR2 cache after ping-pong data processing. Finally USB3014 interface chip transmits data via automatic-dma approach and uploads to PC by USB3.0 cable. During the manufacture of aerial imaging spectrometer, the DAS can achieve image acquisition, transmission, storage and display. All functions can provide the necessary test detection for aerial imaging spectrometer. The test shows that system performs stable and no data lose. Average transmission speed and storage speed of writing SSD can stabilize at 1.28Gbps. Consequently ,this data acquisition system can meet application requirements for aerial imaging spectrometer.

  8. Personal computer based Fourier transform ion cyclotron resonance mass spectrometer

    NASA Astrophysics Data System (ADS)

    Guan, Shenheng; Jones, Patrick R.

    1988-12-01

    An IBM PC AT compatible computer is used to host the interface of a Fourier transform ion cyclotron resonance mass spectrometer or FTMS. A common fast memory bank for both ion-excitation waveform and data acquisition is reserved in the computer's system memory space. All the digital electronics circuitry is assembled on an IBM PC AT extension board. Neither an external frequency synthesizer nor a waveform digitizer is needed. Ion-excitation waveforms can be generated in either frequency-sweeping or inverse-Fourier transform modes. Both excitation and data acquisition can be carried out at eight megawords per second.

  9. 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.

  10. New μSR spectrometer at J-PARC MUSE based on Kalliope detectors

    NASA Astrophysics Data System (ADS)

    Kojima, K. M.; Murakami, T.; Takahashi, Y.; Lee, H.; Suzuki, S. Y.; Koda, A.; Yamauchi, I.; Miyazaki, M.; Hiraishi, M.; Okabe, H.; Takeshita, S.; Kadono, R.; Ito, T.; Higemoto, W.; Kanda, S.; Fukao, Y.; Saito, N.; Saito, M.; Ikeno, M.; Uchida, T.; Tanaka, M. M.

    2014-12-01

    We developed a new positron detector system called Kalliope, which is based on multi-pixel avalanch photo-diode (m-APD), application specific integrated circuit (ASIC), field programmable gated array (FPGA) and ethernet-based SiTCP data transfer technology. We have manufactured a general-purpose spectrometer for muon spin relaxation (μSR) measurements, employing 40 Kalliope units (1280 channels of scintillators) installed in a 0.4 T longitudinal-field magnet. The spectrometer has been placed at D1 experimental area of J- PARC Muon Science Establishment (MUSE). Since February of 2014, the spectrometer has been used for the user programs of MUSE after a short commissioning period of one week. The data accumulation rate of the new spectrometer is 180 million positron events per hour (after taking the coincidence of two scintillators of telescopes) from a 20×20 mm sample for double-pulsed incoming muons.

  11. Transmission grating based extreme ultraviolet imaging spectrometer for time and space resolved impurity measurements.

    PubMed

    Kumar, Deepak; Stutman, Dan; Tritz, Kevin; Finkenthal, Michael; Tarrio, Charles; Grantham, Steven

    2010-10-01

    A free standing transmission grating based imaging spectrometer in the extreme ultraviolet range has been developed for the National Spherical Torus Experiment (NSTX). The spectrometer operates in a survey mode covering the approximate spectral range from 30 to 700 Å and has a resolving capability of δλ/λ on the order of 3%. Initial results from space resolved impurity measurements from NSTX are described in this paper.

  12. Vegetation species composition and canopy architecture information expressed in leaf water absorption measured in the 1000 nm and 2200 spectral region by an imaging spectrometer

    NASA Technical Reports Server (NTRS)

    Green, Robert O.; Roberts, Dar A.

    1995-01-01

    Plant species composition and plant architectural attributes are critical parameters required for the measuring, monitoring, and modeling of terrestrial ecosystems. Remote sensing is commonly cited as an important tool for deriving vegetation properties at an appropriate scale for ecosystem studies, ranging from local to regional and even synoptic scales. Classical approaches rely on vegetation indices such as the normalized difference vegetation index (NDVI) to estimate biophysical parameters such as leaf area index or intercepted photosynthetically active radiation (IPAR). Another approach is to apply a variety of classification schemes to map vegetation and thus extrapolate fine-scale information about specific sites to larger areas of similar composition. Imaging spectrometry provides additional information that is not obtainable through broad-band sensors and that may provide improved inputs both to direct biophysical estimates as well as classification schemes. Some of this capability has been demonstrated through improved discrimination of vegetation, estimates of canopy biochemistry, and liquid water estimates from vegetation. We investigate further the potential of leaf water absorption estimated from Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data as a means for discriminating vegetation types and deriving canopy architectural information. We expand our analysis to incorporate liquid water estimates from two spectral regions, the 1000-nm region and the 2200-nm region. The study was conducted in the vicinity of Jasper Ridge, California, which is located on the San Francisco peninsula to the west of the Stanford University campus. AVIRIS data were acquired over Jasper Ridge, CA, on June 2, 1992, at 19:31 UTC. Spectra from three sites in this image were analyzed. These data are from an area of healthy grass, oak woodland, and redwood forest, respectively. For these analyses, the AVIRIS-measured upwelling radiance spectra for the entire Jasper

  13. A miniaturized NQR spectrometer for a multi-channel NQR-based detection device.

    PubMed

    Beguš, Samo; Jazbinšek, Vojko; Pirnat, Janez; Trontelj, Zvonko

    2014-10-01

    A low frequency (0.5-5 MHz) battery operated sensitive pulsed NQR spectrometer with a transmitter power up to 5 W and a total mass of about 3 kg aimed at detecting (14)N NQR signals, predominantly of illicit materials, was designed and assembled. This spectrometer uses a standard software defined radio (SDR) platform for the data acquisition unit. Signal processing is done with the LabView Virtual instrument on a personal computer. We successfully tested the spectrometer by measuring (14)N NQR signals from aminotetrazole monohydrate (ATMH), potassium nitrate (PN), paracetamol (PCM) and trinitrotoluene (TNT). Such a spectrometer is a feasible component of a portable single or multichannel (14)N NQR based detection device.

  14. Spectral resolution measurement technique for Czerny-Turner spectrometers based on spectral interferometry

    NASA Astrophysics Data System (ADS)

    Contreras Martínez, Ramiro; Garduño Mejía, Jesús; Rosete Aguilar, Martha; Román Moreno, Carlos J.

    2016-08-01

    We propose the design of a new technique for measuring the spectral resolution of a Czerny-Turner Spectrometer based on spectral interferometry of ultrashort laser pulses. It is well known that ultrashort pulse measurement like SPIDER and TADPOLE techniques requires a precise and well characterized spectrum, especially in fringe resolution. We developed a new technique, to our knowledge, in which by measuring the nominal fringe spacing of a spectral interferogram one can characterize the spectral resolution in a Czerny-Turner spectrometer using Ryleigh's criteria. This technique was tested in a commercial Czerny-Turner spectrometer. The results demonstrate a consistent spectral resolution between what was reported by the manufacturer. The actual calibration technique was applied in a homemade broadband astigmatism-free Czerny-Turner spectrometer. Theory and experimental results are presented.

  15. A miniaturized NQR spectrometer for a multi-channel NQR-based detection device

    NASA Astrophysics Data System (ADS)

    Beguš, Samo; Jazbinšek, Vojko; Pirnat, Janez; Trontelj, Zvonko

    2014-10-01

    A low frequency (0.5-5 MHz) battery operated sensitive pulsed NQR spectrometer with a transmitter power up to 5 W and a total mass of about 3 kg aimed at detecting 14N NQR signals, predominantly of illicit materials, was designed and assembled. This spectrometer uses a standard software defined radio (SDR) platform for the data acquisition unit. Signal processing is done with the LabView Virtual instrument on a personal computer. We successfully tested the spectrometer by measuring 14N NQR signals from aminotetrazole monohydrate (ATMH), potassium nitrate (PN), paracetamol (PCM) and trinitrotoluene (TNT). Such a spectrometer is a feasible component of a portable single or multichannel 14N NQR based detection device.

  16. Isotopic response with small scintillator based gamma-ray spectrometers

    DOEpatents

    Madden, Norman W [Sparks, NV; Goulding, Frederick S [Lafayette, CA; Asztalos, Stephen J [Oakland, CA

    2012-01-24

    The intrinsic background of a gamma ray spectrometer is significantly reduced by surrounding the scintillator with a second scintillator. This second (external) scintillator surrounds the first scintillator and has an opening of approximately the same diameter as the smaller central scintillator in the forward direction. The second scintillator is selected to have a higher atomic number, and thus has a larger probability for a Compton scattering interaction than within the inner region. Scattering events that are essentially simultaneous in coincidence to the first and second scintillators, from an electronics perspective, are precluded electronically from the data stream. Thus, only gamma-rays that are wholly contained in the smaller central scintillator are used for analytic purposes.

  17. Validation of ACE-FTS measurements of CFC-11, CFC-12, and HCFC-22 using ground-based FTIR spectrometers

    NASA Astrophysics Data System (ADS)

    Kolonjari, F.; Walker, K. A.; Mahieu, E.; Batchelor, R. L.; Bernath, P. F.; Boone, C.; Conway, S. A.; Dan, L.; Griffin, D.; Harrett, A.; Kasai, Y.; Kagawa, A.; Lindenmaier, R.; Strong, K.; Whaley, C.

    2013-12-01

    Satellite datasets can be an effective global monitoring tool for long-lived compounds in the atmosphere. The Atmospheric Chemistry Experiment (ACE) is a mission on-board the Canadian satellite SCISAT-1. The primary instrument on SCISAT-1 is a high-resolution infrared Fourier transform spectrometer (ACE-FTS) which is capable of measuring a range of gases including key chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC) species. These families of species are of interest because of their significant contribution to anthropogenic ozone depletion and to global warming. To assess the quality of data derived from satellite measurements, validation using other data sources is essential. Ground-based Fourier transform infrared (FTIR) spectrometers are particularly useful for this purpose. In this study, five FTIR spectrometers located at four sites around the world are used to validate the CFC-11 (CCl3F), CFC-12 (CCl2F2), and HCFC-22 (CHClF2) retrieved profiles from ACE-FTS measurements. These species are related because HCFC-22 was the primary replacement for CFC-11 and CFC-12 in refrigerant and propellant applications. The FTIR spectrometers used in this study record solar absorption spectra at Eureka (Canada), Jungfraujoch (Switzerland), Poker Flat (USA), and Toronto (Canada). The retrieval of CFC-11, CFC-12, and HCFC-22 are not standard products for many of these instruments, and as such, a harmonization of retrieval parameters between the sites has been conducted. The retrievals of these species from the FTIR spectra are sensitive from the surface to approximately 20 km, while the ACE-FTS profiles extend from approximately 6 to 30 km. For each site, partial column comparisons between coincident measurements of the three species and a validation of the observed trends will be discussed.

  18. Ground-based high resolution Fourier transform spectrometer and its application in Beijing

    NASA Astrophysics Data System (ADS)

    Fan, Dongdong

    2013-10-01

    The B3M-FTS instrument, inherited from ACE-FTS and PARIS, is built by Canadian ABB and Beijing Vision Sky Aerospace Co., Ltd. The B3M is a complete stand-alone spectrometer designed to operate from the ground in moderate environment. It can acquire atmospheric spectra with the Sun as back illumination. This instrument is an adapted version of the classical Michelson interferometer using an optimized optical layout, and it is a high-resolution infrared Fourier transform spectrometer operating in the 750 to 4100cm-1 spectral range. In this paper, the instrument concept of a compact, portable, high-resolution Fourier transform spectrometer is introduced. Some test results of the instrument such as ILS and SNR are presented, and the spectral resolution of 0.028cm-1 @ 750cm-1 and SNR over 100:1 are achieved. Sample atmospheric absorption spectra and corresponding retrieval results measured by the FTS are given. The B3M-FTS, with its high performance, provides the capability to monitor the atmospheric composition changes by measuring the atmospheric absorption spectra of solar radiance. Lots of measurements have been acquired at the Olympics atmospheric observation super-station. Up to now, the VMRs of near 10 trace gases have been retrieved. The success of atmospheric composition profile retrieval using the FTS measurements makes the further application of FTS type payload possible in China.

  19. The design and simulation of single detector MIR spectrometer based on MEMS scanning mirror

    NASA Astrophysics Data System (ADS)

    Zhang, Zhong-wei; Wen, Zhi-yu; Zeng, Tian-ling; Wei, Kang-lin

    2011-08-01

    Infrared (IR) spectrometers are very important optical equipments that can be used in industry, science, medicine, agriculture, biology and food safety etc., and the market is growing. However, most traditional IR spectrometers, such as Fourier transform spectrometer (FTS) that based on Michelson interferometer principle and scanning monochromator that based on grating scanning, are expensive, relative large volume, and stationary, which can't meet the requirements of specific application such as rapidity, special environment and some special samples. To overcome these drawbacks, innovatory technology-micro electro mechanical systems (MEMS) technology was used in micro IR spectrometers in the past few years. And several prototypes and products that based on several operational principles have been emerged. In this paper, a novel IR micro spectrometer which based on MEMS technology and used single element detector was presented over a wide spectral range (from 2500nm to 5000nm) in the mid infrared (MIR) wavelength regime, and the optical system of it was designed on the basis of traditional scanning monochromator principle. In the optical system, there is a highlighted characteristic that dual spherical focus mirror was used to focus the diffraction light of the diffraction grating, which improved the spectral resolution of the optical system. Finally, using Zemax optical software, three torsion angle locations were selected to simulate the optical system of the spectrometer with the slit's size 0.1mm×1mm. The simulation result indicated that in the whole wavelength range the spectral resolution of the optical system was less than 30nm, and a high accuracy MIR spectrometer with compact volume will be realized in future hopefully.

  20. Design and construction of an Offner spectrometer based on geometrical analysis of ring fields.

    PubMed

    Kim, Seo Hyun; Kong, Hong Jin; Lee, Jong Ung; Lee, Jun Ho; Lee, Jai Hoon

    2014-08-01

    A method to obtain an aberration-corrected Offner spectrometer without ray obstruction is proposed. A new, more efficient spectrometer optics design is suggested in order to increase its spectral resolution. The derivation of a new ring equation to eliminate ray obstruction is based on geometrical analysis of the ring fields for various numerical apertures. The analytical design applying this equation was demonstrated using the optical design software Code V in order to manufacture a spectrometer working in wavelengths of 900-1700 nm. The simulation results show that the new concept offers an analytical initial design taking the least time of calculation. The simulated spectrometer exhibited a modulation transfer function over 80% at Nyquist frequency, root-mean-square spot diameters under 8.6 μm, and a spectral resolution of 3.2 nm. The final design and its realization of a high resolution Offner spectrometer was demonstrated based on the simulation result. The equation and analytical design procedure shown here can be applied to most Offner systems regardless of the wavelength range.

  1. A graphene-based Fabry-Pérot spectrometer in mid-infrared region

    NASA Astrophysics Data System (ADS)

    Wang, Xiaosai; Chen, Chen; Pan, Liang; Wang, Jicheng

    2016-08-01

    Mid-infrared spectroscopy is of great importance in many areas and its integration with thin-film technology can economically enrich the functionalities of many existing devices. In this paper we propose a graphene-based ultra-compact spectrometer (several micrometers in size) that is compatible with complementary metal-oxide-semiconductor (CMOS) processing. The proposed structure uses a monolayer graphene as a mid-infrared surface waveguide, whose optical response is spatially modulated using electric fields to form a Fabry-Pérot cavity. By varying the voltage acting on the cavity, we can control the transmitted wavelength of the spectrometer at room temperature. This design has potential applications in the graphene-silicon-based optoelectronic devices as it offers new possibilities for developing new ultra-compact spectrometers and low-cost hyperspectral imaging sensors in mid-infrared region.

  2. Integration of spectral coronagraphy within VIPA-based spectrometers for high extinction Brillouin imaging

    NASA Astrophysics Data System (ADS)

    Edrei, Eitan; Gather, Malte C.; Scarcelli, Giuliano

    2017-03-01

    VIPA-based spectrometers have enabled rapid Brillouin spectrum measurements and current designs of multi-stage VIPA spectrometers offer enough spectral extinction to probe transparent tissue, cells and biomaterials. However, in highly scattering media or in the presence of strong back-reflections, such as at interfaces between materials of different refractive indices, VIPA-based Brillouin spectral measurements are limited. While several approaches to address this issue have recently been pursued, important challenges remain. Here we have adapted the design of coronagraphs used for exosolar planet imaging to the spectral domain and integrated it in a double-stage VIPA spectrometer. We demonstrate that this yields an increase in extinction up to 20dB, with nearly no added insertion loss. The power of this improvement is vividly demonstrated by Brillouin imaging close to reflecting interfaces without need of index matching or sample tilting

  3. A graphene-based Fabry-Pérot spectrometer in mid-infrared region

    PubMed Central

    Wang, Xiaosai; Chen, Chen; Pan, Liang; Wang, Jicheng

    2016-01-01

    Mid-infrared spectroscopy is of great importance in many areas and its integration with thin-film technology can economically enrich the functionalities of many existing devices. In this paper we propose a graphene-based ultra-compact spectrometer (several micrometers in size) that is compatible with complementary metal-oxide-semiconductor (CMOS) processing. The proposed structure uses a monolayer graphene as a mid-infrared surface waveguide, whose optical response is spatially modulated using electric fields to form a Fabry-Pérot cavity. By varying the voltage acting on the cavity, we can control the transmitted wavelength of the spectrometer at room temperature. This design has potential applications in the graphene-silicon-based optoelectronic devices as it offers new possibilities for developing new ultra-compact spectrometers and low-cost hyperspectral imaging sensors in mid-infrared region. PMID:27573080

  4. Signal to Noise Ratio in Digital Lock-in Detection for Multiple Intensity-Modulated Signals in CO2 Laser Absorption Spectrometer

    NASA Astrophysics Data System (ADS)

    CHEN, S.; Lin, B.; Harrison, F. W.; Nehrir, A. R.; Campbell, J. F.; Refaat, T.; Abedin, N. M.; Obland, M. D.; Ismail, S.; Meadows, B. L.

    2013-12-01

    NASA Langley Research Center is investigating Intensity-Modulated, Continuous-Wave Laser Absorption Spectrometers (LASs) for the measurement of atmospheric carbon dioxide (CO2) column mixing ratio from both air- and space-borne platforms. The LAS system uses high-power fiber lasers/amplifiers in the 1.57-um CO2 absorption band and the 1.26-um O2 absorption band in the transmitters and simultaneous digital lock-in detection for the multiple intensity-modulated signals with different modulation waveforms , such as simple sinusoidal waves at different frequencies, associated with different wavelengths in the receivers. The Signal to Noise Ratio (SNR) of the simultaneous digital lock-in detection in the system is of interest for the system designs and the performance prediction of airborne and space-borne implementations in the future. This paper will discuss the properties of the signals and various noises in the LAS system, especially for the simultaneous digital lock-in detection with a single detector for the multiple intensity-modulated signals at different frequencies. The numerical simulation of the SNR for the simultaneous digital lock-in detection in terms of relative intensity of the multiple modulated signals and the integration time, and an initial experimental verification will be presented.

  5. Laser Magneto-Optic Rotation Spectrometer (LMORS)

    DTIC Science & Technology

    1998-01-01

    traditional method of measuring atomic concentrations uses atomic absorption spectroscopy (AAS), herein referred to as an AAS 15 spectrometer...MOR spectrometer of the present invention. Fig. 2 illustrates a calibration curve for a conventional 10 atomic absorption spectroscopy (AAS

  6. 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.

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

    SciTech Connect

    Miyake, H.; Matsuyama, M.; Watanabe, K. ); Cowgill, D.F. )

    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 for 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.

  8. Design and experiment of spectrometer based on scanning micro-grating integrating with angle sensor

    NASA Astrophysics Data System (ADS)

    Biao, Luo; Wen, Zhi-yu

    2014-01-01

    A compact, low cost, high speed, non-destructive testing NIR (near infrared) spectrometer optical system based on MOEMS grating device is developed. The MOEMS grating works as the prismatic element and wavelength scanning element in our optical system. The MOEMS grating enables the design of compact grating spectrometers capable of acquiring full spectra using a single detector element. This MOEMS grating is driven by electromagnetic force and integrated with angle sensor which used to monitored deflection angle while the grating working. Comparing with the traditional spectral system, there is a new structure with a single detector and worked at high frequency. With the characteristics of MOEMS grating, the structure of the spectrometer system is proposed. After calculating the parameters of the optical path, ZEMAX optical software is used to simulate the system. According the ZEMAX output file of the 3D model, the prototype is designed by SolidWorks rapidly, fabricated. Designed for a wavelength range between 800 nm and 1500 nm, the spectrometer optical system features a spectral resolution of 16 nm with the volume of 97 mm × 81.7 mm × 81 mm. For the purpose of reduce modulated effect of sinusoidal rotation, spectral intensity of the different wavelength should be compensated by software method in the further. The system satisfies the demand of NIR micro-spectrometer with a single detector.

  9. 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.

  10. Tunable fiber laser based photoacoustic spectrometer for breath ammonia analysis during hemodialysis

    NASA Astrophysics Data System (ADS)

    Wang, J. W.; Xie, H.; Liang, L. R.; Zhang, W.; Peng, W.; Yu, Q. X.

    2011-11-01

    A photoacoustic (PA) spectrometer based on a near-IR tunable fiber laser is developed and used for breath ammonia analysis. We successfully measured the breath ammonia level variation of six patients with end-stage renal disease while they were undergoing hemodialysis in the hospital. The measurement results showed that the initial concentration level of the breath ammonia were from 1600 to 2200 ppb before dialysis treatment, the levels decreased to 200-600 ppb in the end stage of dialysis, which close to the levels of healthy persons. Further improvement and applications of this PA spectrometer are discussed.

  11. Collection optics for a Raman spectrometer based on the 90° geometry of scattered light collection.

    PubMed

    Petrov, Dmitry V; Matrosov, Ivan I; Sedinkin, Danila O

    2016-10-10

    In the present work, efficiency of classical lens, mirror-lens, and pure mirror variants of the collection optics for a Raman spectrometer based on 90° geometry of scattered light collection is investigated. It is experimentally established that, despite a smaller collection angle, in the case of a relatively narrow input slit of the spectrometer (<100  μm), the lens optics with corrected off-axis and chromatic aberrations allows larger signal intensities to be registered. However, the low f/# mirror collection optics described in the work provide a more stable adjustment and can be used to increase the Raman signal intensities in cases when the image of the scattering volume formed by them is commensurable with the sizes of the input slit of the spectrometer.

  12. Calibration of a microchannel plate based extreme ultraviolet grazing incident spectrometer at the Advanced Light Source.

    PubMed

    Bakeman, M S; van Tilborg, J; Sokollik, T; Baum, D; Ybarrolaza, N; Duarte, R; Toth, C; Leemans, W P

    2010-10-01

    We present the design and calibration of a microchannel plate based extreme ultraviolet spectrometer. Calibration was performed at the Advance Light Source (ALS) at the Lawrence Berkeley National Laboratory (LBNL). This spectrometer will be used to record the single shot spectrum of radiation emitted by the tapered hybrid undulator (THUNDER) undulator installed at the LOASIS GeV-class laser-plasma-accelerator. The spectrometer uses an aberration-corrected concave grating with 1200 lines/mm covering 11-62 nm and a microchannel plate detector with a CsI coated photocathode for increased quantum efficiency in the extreme ultraviolet. A touch screen interface controls the grating angle, aperture size, and placement of the detector in vacuum, allowing for high-resolution measurements over the entire spectral range.

  13. Calibration of a microchannel plate based extreme ultraviolet grazing incident spectrometer at the Advanced Light Source

    SciTech Connect

    Bakeman, M. S.; Tilborg, J. van; Sokollik, T.; Baum, D.; Ybarrolaza, N.; Duarte, R.; Toth, C.; Leemans, W. P.

    2010-10-15

    We present the design and calibration of a microchannel plate based extreme ultraviolet spectrometer. Calibration was performed at the Advance Light Source (ALS) at the Lawrence Berkeley National Laboratory (LBNL). This spectrometer will be used to record the single shot spectrum of radiation emitted by the tapered hybrid undulator (THUNDER) undulator installed at the LOASIS GeV-class laser-plasma-accelerator. The spectrometer uses an aberration-corrected concave grating with 1200 lines/mm covering 11-62 nm and a microchannel plate detector with a CsI coated photocathode for increased quantum efficiency in the extreme ultraviolet. A touch screen interface controls the grating angle, aperture size, and placement of the detector in vacuum, allowing for high-resolution measurements over the entire spectral range.

  14. Spectrometer for hard X-ray free-electron laser based on diffraction focusing.

    PubMed

    Kohn, V G; Gorobtsov, O Y; Vartanyants, I A

    2013-03-01

    X-ray free-electron lasers (XFELs) generate sequences of ultra-short spatially coherent pulses of X-ray radiation. A diffraction focusing spectrometer (DFS), which is able to measure the whole energy spectrum of the radiation of a single XFEL pulse with an energy resolution of ΔE/E 2 × 10(-6), is proposed. This is much better than for most modern X-ray spectrometers. Such resolution allows one to resolve the fine spectral structure of the XFEL pulse. The effect of diffraction focusing occurs in a single-crystal plate due to dynamical scattering, and is similar to focusing in a Pendry lens made from a metamaterial with a negative refraction index. Such a spectrometer is easier to operate than those based on bent crystals. It is shown that the DFS can be used in a wide energy range from 5 keV to 20 keV.

  15. Broadband Single-Shot Electron Spectrometer for GeV-Class Laser Plasma Based Accelerators

    SciTech Connect

    Nakamura, K.; Wan, W.; Ybarrolaza, N.; Syversrud, D.; Wallig, J.; Leemans, W.P.

    2008-05-01

    Laser-plasma-based accelerators can provide electrons over a broad energy range and/or with large momentum spread. The electron beam energy distribution can be controlled via accurate control of laser and plasma properties, and beams with energies ranging from'0.5 to 1000 MeV have been observed. Measuring these energy distributions in a single shot requires the use of a diagnostic with large momentum acceptance and, ideally, sufficient resolution to accurately measure energy spread in the case of narrow energy spread. Such a broadband single-shot electron magnetic spectrometer for GeV-class laser-plasma-based accelerators has been developed at Lawrence Berkeley National Laboratory. A detailed description of the hardware and the design concept is presented, as well as a performance evaluation of the spectrometer. The spectrometer covered electron beam energies raging from 0.01 to 1.1 GeV in a single shot, and enabled the simultaneous measurement of the laser properties at the exit of the accelerator through the use of a sufficiently large pole gap. Based on measured field maps and 3rd-order transport analysis, a few percent-level resolution and determination of the absolute energy were achieved over the entire energy range. Laser-plasma-based accelerator experiments demonstrated the capability of the spectrometer as a diagnostic and its suitability for such a broadband electron source.

  16. ARO Research Instrumentation Program - IR Spectrometer Procurement

    DTIC Science & Technology

    2015-11-01

    via simultaneous electrochemical and spectroscopic studies. These studies are enabling us to understanding the microscopic (molecular and ionic...program. The instrument is being utilized to characterize ionic liquid-based (IL-based) electrolyte systems via simultaneous electrochemical and...spectrometer has been synchronized with a potentiostat to perform surface enhanced infrared absorption (SEIRA) spectroscopy during electrochemical

  17. Response of silicon-Based Linear Energy Transfer Spectrometers

    NASA Technical Reports Server (NTRS)

    Aman, A.; Bman, B.; Badhwar, G. D.; ONeill, P. M. O.

    2000-01-01

    Silicon-based linear energy transfer (LET) telescope,(e. g., DOSTEL and RRMD) have recently been flown in space. LET spectra measured using tissue equivalent proportional counters show differences that need to be fully understood. A Monte Carlo technique based on: 1. radiation transport cluster intra-cascade model. 2. Landau-Vavilov distribution, 3. telescope geometry and detector coincidence & discriminator settings, 4. spacecraft shielding geometry, and 5. the external free space radiation environment, including recent albedo measurements, was developed.

  18. Evaluation of the absorption of methotrexate on cells and its cytotoxicity assay by using an integrated microfluidic device coupled to a mass spectrometer.

    PubMed

    Gao, Dan; Li, Haifang; Wang, Niejun; Lin, Jin-Ming

    2012-11-06

    An integrated microfluidic device was developed for high-throughput drug screening with an online electrospray ionization quadrupole time-of-flight mass spectrometer (ESI-Q-TOF MS). The multiple gradient generator followed by an array of microscale cell culture chambers and on-chip solid-phase extraction (SPE) columns for sample pretreatment prior to mass analysis was integrated in the device which was fabricated in one single step. By using the combination system, the process for characterization of drug absorption and evaluation of cytotoxicity could be simultaneously realized. To validate the feasibility, the absorption of methotrexate and its effects on HepG2 and Caco-2 cells were investigated. With the increasing concentration of drugs, the percentage of apoptotic cells appeared in a dose-dependent fashion. By comparison with the results obtained from ESI-Q-TOF MS analysis and cytotoxicity assay, we found that higher intracellular drug concentration resulted in increased cell cytotoxicity. The technique presented herein provides an easy protocol to screen drugs rapidly with low drug consumption, high throughput, and high sensitivity.

  19. Inter-comparison of 2 microm Heterodyne Differential Absorption Lidar, Laser Diode Spectrometer, LICOR NDIR analyzer and flasks measurements of near-ground atmospheric CO2 mixing ratio.

    PubMed

    Gibert, Fabien; Joly, Lilian; Xuéref-Rémy, Irène; Schmidt, Martina; Royer, Adrien; Flamant, Pierre H; Ramonet, Michel; Parvitte, Bertrand; Durry, Georges; Zéninari, Virginie

    2009-01-01

    Remote sensing and in situ instruments are presented and compared in the same location for accurate CO(2) mixing ratio measurements in the atmosphere: (1) a 2.064 microm Heterodyne DIfferential Absorption Lidar (HDIAL), (2) a field deployable infrared Laser Diode Spectrometer (LDS) using new commercial diode laser technology at 2.68 microm, (3) LICOR NDIR analyzer and (4) flasks. LDS, LICOR and flasks measurements were made in the same location, LICOR and flasks being taken as reference. Horizontal HDIAL measurements of CO(2) absorption using aerosol backscatter signal are reported. Using new spectroscopic data in the 2 microm band and meteorological sensor measurements, a mean CO(2) mixing ratio is inferred by the HDIAL in a 1 km long path above the 15m height location of the CO(2) in situ sensors. We compare HDIAL and LDS measurements with the LICOR data for 30 min of time averaging. The mean standard deviation of the HDIAL and the LDS CO(2) mixing ratio results are 3.3 ppm and 0.89 ppm, respectively. The bias of the HDIAL and the LDS measurements are -0.54 ppm and -0.99 ppm, respectively.

  20. Fast time response measurements of gaseous nitrous acid using a tunable diode laser absorption spectrometer: HONO emission source from vehicle exhausts

    NASA Astrophysics Data System (ADS)

    Li, Yongquan Q.; Schwab, James J.; Demerjian, Kenneth L.

    2008-02-01

    We present the measurement of gaseous nitrous acid (HONO) using a tunable diode laser absorption spectrometer. This method utilizes one strong absorption feature at 1713.511cm-1, which is free of interference and suitable for ambient HONO measurements. The detection limit for a 1-second integration time is determined to be better than 200 pptv. The measurement method has been demonstrated by sampling room air over an 11-day period. HONO mixing ratios ranged from below the detection limit (<=200 pptv) to 4.8 ppbv, with a mean value of 0.73 ppbv. A number of elevated HONO events lasting from several seconds up to hours were observed and have been associated with roadway traffic adjacent to the building where the measurements were performed. The variation in the ratio of HONO/NOx and its anti-correlation with ambient NOx measurements indicate that the source of HONO in this measurement study is mainly from the direct emission of traffic exhausts and local heterogeneous reactions. The demonstrated application of TDLAS fast response measurement technology is capable of providing new information on the sources and sinks of HONO in the environment.

  1. Smartphone spectrometer for non-invasive diffuse reflectance spectroscopy based hemoglobin sensing (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Edwards, Perry S.

    2016-10-01

    Fiber-optic based diffuse reflectance spectroscopy (DRS) is shown to be a highly specific and highly sensitive method for non-invasive detection of various cancers (e.g. cervical and oral) as well as many other diseases. Fiber-optic DRS diagnosis relies on non-invasive biomarker detection (e.g. oxy- and deoxy-hemoglobin) and can be done without the need for sophisticated laboratory analysis of samples. Thus, it is highly amenable for clinical adoption especially in resource scarce regions that have limited access to such developed laboratory infrastructure. Despite the demonstrated effectiveness of fiber-optic DRS, such systems remain cost prohibitive in many of these regions, mainly due to the use of bulky and expensive spectrometers. Here, a fiber-optic DRS system is coupled to a smartphone spectrometer and is proposed as a low-cost solution for non-invasive tissue hemoglobin sensing. The performance of the system is assessed by measuring tissue phantoms with varying hemoglobin concentrations. A DRS retrieval algorithm is used to extract hemoglobin parameters from the measurements and determine the accuracy of the system. The results are then compared with those of a previously reported fiber-optic DRS system which is based on a larger more expensive spectrometer system. The preliminary results are encouraging and indicate the potential of the smartphone spectrometer as a viable low-cost option for non-invasive tissue hemoglobin sensing.

  2. 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.

  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. Design of imaging spectrometer based on Czerny-Turner in FUV

    NASA Astrophysics Data System (ADS)

    Liu, Jianpeng; Tang, Yi; Wu, Yan; Zhang, Zhige; Ni, Guoqiang

    2010-11-01

    It is the astigmatism that leads the traditional imaging spectrometer based on Czerny-Turner to have low spatial resolution. And it is discovered that when the distance between concave mirror and grating, x, is equal to the twice of focal length, ?, of the mirror, SII = SIII = 0 and the aberration is the least as well as the astigmatism is eliminated greatly. Meanwhile the toroidal mirror is presented to correct the astigmatism, and as well the aberration caused by the large FOV is corrected by optimizing the surface tilt. Then both of the spatial and spectral resolutions are improved. Finally a Czerny-Turner imaging spectrometer working in FUV (120 nm { 180 nm) with 2.5° FOV is designed, and its focal length is 147.61 mm, its F number is 3.93. MTF of this imaging spectrometer is more than 0.39 at 20 lp/mm in the total wavelength band of FOV, which satisfied the requirements of imaging spectrometer working on satellite in FUV.

  5. QCL- and CO_2 Laser-Based Mid-Ir Spectrometers for High Accuracy Molecular Spectroscopy

    NASA Astrophysics Data System (ADS)

    Sow, P. L. T.; Chanteau, B.; Auguste, F.; Mejri, S.; Tokunaga, S. K.; Argence, B.; Lopez, O.; Chardonnet, C.; Amy-Klein, A.; Daussy, C.; Darquie, B.; Nicolodi, D.; Abgrall, M.; Le Coq, Y.; Santarelli, G.

    2013-06-01

    With their rich internal structure, molecules can play a decisive role in precision tests of fundamental physics. They are now being used, for example in our group, to test fundamental symmetries such as parity and time reversal, and to measure either absolute values of fundamental constants or their temporal variation. Most of those experiments can be cast as the measurement of molecular frequencies. Ultra-stable and accurate sources in the mid-IR spectral region, the so-called molecular fingerprint region that hosts many intense rovibrational signatures, are thus highly desirable. We report on the development of a widely tunable quantum cascade laser (QCL) based spectrometer. Our first characterization of a free-running cw near-room-temperature DFB 10.3 μm QCL led to a ˜200 kHz linewidth beat-note with our frequency-stabilized CO_2 laser. Narrowing of the QCL linewidth was achieved by straightforwardly phase-locking the QCL to the CO_2 laser. The great stability of the CO_2 laser was transferred to the QCL resulting in a record linewidth of a few tens of hertz. The use of QCLs will allow the study of any species showing absorption between 3 and 25 μm which will broaden the scope of our experimental setups dedicated to molecular spectroscopy-based precision measurements. Eventually we want to lock the QCL to a frequency comb itself stabilized to an ultra-stable near-IR reference provided via a 43-km long fibre by the French metrological institute and monitored against atomic fountain clocks. We report on the demonstration of this locking-scheme with a ˜10 μm CO_2 laser resulting in record 10^{-14}-10^{-15} fractional accuracy and stability. Stabilizing a QCL this way will free us from having to lock it to a molecular transition or a CO_2 laser. It will make it possible for any laboratory to have a stabilized QCL at any desired wavelength with spectral performances currently only achievable in the visible and near-IR, in metrological institutes.

  6. Laser-based ultraviolet absorption detection in capillary electrophoresis

    SciTech Connect

    Xue, Y.; Yeung, E.S. )

    1994-04-01

    Laser-based UV absorption in capillary electrophoresis is demonstrated. The use of vacuum photodiodes and an all-electronic noise canceller provides adequate baseline stability despite the large inherent intensity noise in UV lasers. A 4-fold improvement in the detection limit is achieved in comparison to that of commercial instruments. The main advantage here is the better optical coupling with small capillary tubes, maximizing the available optical pathlength for absorption.

  7. Models of filter-based particle light absorption measurements

    NASA Astrophysics Data System (ADS)

    Hamasha, Khadeejeh M.

    Light absorption by aerosol is very important in the visible, near UN, and near I.R region of the electromagnetic spectrum. Aerosol particles in the atmosphere have a great influence on the flux of solar energy, and also impact health in a negative sense when they are breathed into lungs. Aerosol absorption measurements are usually performed by filter-based methods that are derived from the change in light transmission through a filter where particles have been deposited. These methods suffer from interference between light-absorbing and light-scattering aerosol components. The Aethalometer is the most commonly used filter-based instrument for aerosol light absorption measurement. This dissertation describes new understanding of aerosol light absorption obtained by the filter method. The theory uses a multiple scattering model for the combination of filter and particle optics. The theory is evaluated using Aethalometer data from laboratory and ambient measurements in comparison with photoacoustic measurements of aerosol light absorption. Two models were developed to calculate aerosol light absorption coefficients from the Aethalometer data, and were compared to the in-situ aerosol light absorption coefficients. The first is an approximate model and the second is a "full" model. In the approximate model two extreme cases of aerosol optics were used to develop a model-based calibration scheme for the 7-wavelength Aethalometer. These cases include those of very strong scattering aerosols (Ammonium sulfate sample) and very absorbing aerosols (kerosene soot sample). The exponential behavior of light absorption in the strong multiple scattering limit is shown to be the square root of the total absorption optical depth rather than linear with optical depth as is commonly assumed with Beer's law. 2-stream radiative transfer theory was used to develop the full model to calculate the aerosol light absorption coefficients from the Aethalometer data. This comprehensive model

  8. DAC-board based X-band EPR spectrometer with arbitrary waveform control

    PubMed Central

    Kaufmann, Thomas; Keller, Timothy J.; Franck, John M.; Barnes, Ryan P.; Glaser, Steffen J.; Martinis, John M.; Han, Songi

    2013-01-01

    We present arbitrary control over a homogenous spin system, demonstrated on a simple, home-built, electron paramagnetic resonance (EPR) spectrometer operating at 8–10 GHz (X-band) and controlled by a 1 GHz arbitrary waveform generator (AWG) with 42 dB (i.e. 14-bit) of dynamic range. Such a spectrometer can be relatively easily built from a single DAC (digital to analog converter) board with a modest number of stock components and offers powerful capabilities for automated digital calibration and correction routines that allow it to generate shaped X-band pulses with precise amplitude and phase control. It can precisely tailor the excitation profiles “seen” by the spins in the microwave resonator, based on feedback calibration with experimental input. We demonstrate the capability to generate a variety of pulse shapes, including rectangular, triangular, Gaussian, sinc, and adiabatic rapid passage waveforms. We then show how one can precisely compensate for the distortion and broadening caused by transmission into the microwave cavity in order to optimize corrected waveforms that are distinctly different from the initial, uncorrected waveforms. Specifically, we exploit a narrow EPR signal whose width is finer than the features of any distortions in order to map out the response to a short pulse, which, in turn, yields the precise transfer function of the spectrometer system. This transfer function is found to be consistent for all pulse shapes in the linear response regime. In addition to allowing precise waveform shaping capabilities, the spectrometer presented here offers complete digital control and calibration of the spectrometer that allows one to phase cycle the pulse phase with 0.007° resolution and to specify the inter-pulse delays and pulse durations to ≤250 ps resolution. The implications and potential applications of these capabilities will be discussed. PMID:23999530

  9. DAC-board based X-band EPR spectrometer with arbitrary waveform control

    NASA Astrophysics Data System (ADS)

    Kaufmann, Thomas; Keller, Timothy J.; Franck, John M.; Barnes, Ryan P.; Glaser, Steffen J.; Martinis, John M.; Han, Songi

    2013-10-01

    We present arbitrary control over a homogenous spin system, demonstrated on a simple, home-built, electron paramagnetic resonance (EPR) spectrometer operating at 8-10 GHz (X-band) and controlled by a 1 GHz arbitrary waveform generator (AWG) with 42 dB (i.e. 14-bit) of dynamic range. Such a spectrometer can be relatively easily built from a single DAC (digital to analog converter) board with a modest number of stock components and offers powerful capabilities for automated digital calibration and correction routines that allow it to generate shaped X-band pulses with precise amplitude and phase control. It can precisely tailor the excitation profiles "seen" by the spins in the microwave resonator, based on feedback calibration with experimental input. We demonstrate the capability to generate a variety of pulse shapes, including rectangular, triangular, Gaussian, sinc, and adiabatic rapid passage waveforms. We then show how one can precisely compensate for the distortion and broadening caused by transmission into the microwave cavity in order to optimize corrected waveforms that are distinctly different from the initial, uncorrected waveforms. Specifically, we exploit a narrow EPR signal whose width is finer than the features of any distortions in order to map out the response to a short pulse, which, in turn, yields the precise transfer function of the spectrometer system. This transfer function is found to be consistent for all pulse shapes in the linear response regime. In addition to allowing precise waveform shaping capabilities, the spectrometer presented here offers complete digital control and calibration of the spectrometer that allows one to phase cycle the pulse phase with 0.007° resolution and to specify the inter-pulse delays and pulse durations to ⩽250 ps resolution. The implications and potential applications of these capabilities will be discussed.

  10. DAC-board based X-band EPR spectrometer with arbitrary waveform control.

    PubMed

    Kaufmann, Thomas; Keller, Timothy J; Franck, John M; Barnes, Ryan P; Glaser, Steffen J; Martinis, John M; Han, Songi

    2013-10-01

    We present arbitrary control over a homogenous spin system, demonstrated on a simple, home-built, electron paramagnetic resonance (EPR) spectrometer operating at 8-10 GHz (X-band) and controlled by a 1 GHz arbitrary waveform generator (AWG) with 42 dB (i.e. 14-bit) of dynamic range. Such a spectrometer can be relatively easily built from a single DAC (digital to analog converter) board with a modest number of stock components and offers powerful capabilities for automated digital calibration and correction routines that allow it to generate shaped X-band pulses with precise amplitude and phase control. It can precisely tailor the excitation profiles "seen" by the spins in the microwave resonator, based on feedback calibration with experimental input. We demonstrate the capability to generate a variety of pulse shapes, including rectangular, triangular, Gaussian, sinc, and adiabatic rapid passage waveforms. We then show how one can precisely compensate for the distortion and broadening caused by transmission into the microwave cavity in order to optimize corrected waveforms that are distinctly different from the initial, uncorrected waveforms. Specifically, we exploit a narrow EPR signal whose width is finer than the features of any distortions in order to map out the response to a short pulse, which, in turn, yields the precise transfer function of the spectrometer system. This transfer function is found to be consistent for all pulse shapes in the linear response regime. In addition to allowing precise waveform shaping capabilities, the spectrometer presented here offers complete digital control and calibration of the spectrometer that allows one to phase cycle the pulse phase with 0.007° resolution and to specify the inter-pulse delays and pulse durations to ≤ 250 ps resolution. The implications and potential applications of these capabilities will be discussed.

  11. Broadband UV-Vis vibrational coherence spectrometer based on a hollow fiber compressor

    NASA Astrophysics Data System (ADS)

    Gueye, Moussa; Nillon, Julien; Crégut, Olivier; Léonard, Jérémie

    2016-09-01

    We describe a broadband transient absorption (TA) spectrometer devised to excite and probe, in the blue to UV range, vibrational coherence dynamics in organic molecules in condensed phase. A 800-nm Ti:Sa amplifier and a hollow fiber compressor are used to generate a 6-fs short pulse at 1 kHz. Broadband sum frequency generation with the fundamental pulse is implemented to produce a 400-nm, 8-fs Fourier limited short pulse. A UV-Vis white-light supercontinuum is implemented as a probe with intensity self-referencing to achieve a shot-noise-limited sensitivity. Rapid scanning of the pump-probe delay is shown very efficient in suppressing the noise resulting from low-frequency pump intensity fluctuations. Using either of the 800-nm or 400-nm broadband pulses as the pump for TA spectroscopy of organic molecules in solution, we resolve oscillatory signals down to the 320 nm probing wavelength with a 3200 cm-1 FWHM bandwidth. Their Fourier transformation reveals the corresponding molecular vibrational spectra. Finally, we demonstrate the use of this setup as a vibrational coherence spectrometer for the investigation of the vibrational dynamics accompanying the sub-ps C=C photoisomerization of a retinal-like molecular switch through a conical intersection.

  12. Spectrum Reconstruction of a Spatially Modulated Fourier Transform Spectrometer Based on Stepped Mirrors.

    PubMed

    Gao, Jianhua; Liang, Zhongzhu; Liang, Jingqiu; Wang, Weibiao; Lü, Jinguang; Qin, Yuxin

    2016-11-23

    Based on the basic configuration and interference principle of a static step-mirror-based Fourier transform spectrometer, an image segmentation method is proposed to obtain a one-dimensional interferogram. The direct current component of the interferogram is fit using the least squares (LS) method and is subsequently removed. An empirical-mode decomposition-method-based high-pass filter is constructed to denoise the spectrum and enhance the spectral resolution simultaneously. Several experiments were performed and the spectrum is reconstructed based on these methods. The spectrum resolution is 81 cm(-1) at 2254 cm(-1).

  13. The Use of a Microprocessor-Controlled, Video Output Atomic Absorption Spectrometer as an Educational Tool in a Two-Year Technical Curriculum.

    ERIC Educational Resources Information Center

    Kerfoot, Henry B.

    Based on instructional experiences at Charles County Community College, Maryland, this report examines the pedagogical advantage of teaching atomic absorption (AA) spectroscopy with an AA spectrophotometer that is equipped with a microprocessor and video output mechanism. The report first discusses the growing importance of AA spectroscopy in…

  14. 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.

  15. Development of a Quantum Cascade Laser-Based Spectrometer for Measurements of Biogenic Volatile Organic Compounds

    NASA Astrophysics Data System (ADS)

    Stewart, Jacob

    2016-06-01

    Biogenic volatile organic compounds (BVOCs) are emitted into Earth's atmosphere by plants and are among the most abundant reactive organic species in the troposphere. These compounds play an important role in atmospheric chemistry, including the formation of secondary organic aerosols and production of surface-level ozone, a pollutant which can have negative health effects. BVOCs are generally measured and monitored using mass spectrometry and gas chromatography, but infrared spectroscopy is an excellent complementary tool for measuring these species. The development of quantum cascade lasers (QCLs) has provided robust, coherent light sources which give access to fundamental infrared transitions of BVOCs that lie in the ``infrared window'' from 8-14 um. At Connecticut College, we are developing a QCL-based spectrometer for measuring BVOCs with high resolution and high sensitivity. We will present details on the construction of our spectrometer and preliminary data for measurements of isoprene (C_5H_8), the most abundant BVOC in the troposphere.

  16. A All-Vacuum High Resolution Fourier Transform Spectrometer with Absorption Pathlengths up to 352 M: Acetylene Spectrum at 1.4-1.7 Microns.

    NASA Astrophysics Data System (ADS)

    Keppler, Karen Ann

    1995-01-01

    The spectra of acetylene (C_2H _2) and of water vapor have been recorded at room temperature with Doppler- or pressure -broadening-limited resolution at pathlengths up to 352m. The spectra were obtained with the combination of a FTIR (Fourier Transform Infrared) spectrometer, evacuated transfer optics, and a multipass cell of 4m base length. The measurements were performed at the Justus-Liebig-Universitat in Giessen, Germany, using the FTIR spectrometer at that university, the multipass cell assembled at The Ohio State University, and the vacuum transfer optics designed by the author. The regions in which the spectra were recorded are 5900-7150 cm^{-1} and 1850-6600 cm^{-1}. Calibration difficulties pertaining to the determination of the absolute accuracy of the data have been resolved, and molecular parameters have been extracted for the HCCH data. These calibration problems were not documented in earlier studies using high resolution Fourier transform spectrometers. For this reason, the dissertation addresses this matter in somewhat greater detail. This work contains a description of the technology used to obtain the data, and a description of the calibration of the spectra to make them suitable for future use as secondary wavenumber calibration standards. The bands detected for the first time in this study have been reported, and updated energy level diagrams for HCCH and H^{13}CCH have been included. The molecular parameters obtained from the HCCH spectra have been presented. The appendices include, among others, the basic observational data, a spectral map and associated wavenumber lists of HCCH, and a description of the weighting scheme developed by the author for Fourier Transform spectra.

  17. Miniature, Low-Power, Waveguide Based Infrared Fourier Transform Spectrometer for Spacecraft Remote Sensing

    NASA Technical Reports Server (NTRS)

    Hewagama, TIlak; Aslam, Shahid; Talabac, Stephen; Allen, John E., Jr.; Annen, John N.; Jennings, Donald E.

    2011-01-01

    Fourier transform spectrometers have a venerable heritage as flight instruments. However, obtaining an accurate spectrum exacts a penalty in instrument mass and power requirements. Recent advances in a broad class of non-scanning Fourier transform spectrometer (FTS) devices, generally called spatial heterodyne spectrometers, offer distinct advantages as flight optimized systems. We are developing a miniaturized system that employs photonics lightwave circuit principles and functions as an FTS operating in the 7-14 micrometer spectral region. The inteferogram is constructed from an ensemble of Mach-Zehnder interferometers with path length differences calibrated to mimic scan mirror sample positions of a classic Michelson type FTS. One potential long-term application of this technology in low cost planetary missions is the concept of a self-contained sensor system. We are developing a systems architecture concept for wide area in situ and remote monitoring of characteristic properties that are of scientific interest. The system will be based on wavelength- and resolution-independent spectroscopic sensors for studying atmospheric and surface chemistry, physics, and mineralogy. The self-contained sensor network is based on our concept of an Addressable Photonics Cube (APC) which has real-time flexibility and broad science applications. It is envisaged that a spatially distributed autonomous sensor web concept that integrates multiple APCs will be reactive and dynamically driven. The network is designed to respond in an event- or model-driven manner or reconfigured as needed.

  18. Thermostatic system of sensor in NIR spectrometer based on PID control

    NASA Astrophysics Data System (ADS)

    Wang, Zhihong; Qiao, Liwei; Ji, Xufei

    2016-11-01

    Aiming at the shortcomings of the primary sensor thermostatic control system in the near infrared (NIR) spectrometer, a novel thermostatic control system based on proportional-integral-derivative (PID) control technology was developed to improve the detection precision of the NIR spectrometer. There were five parts including bridge amplifier circuit, analog-digital conversion (ADC) circuit, microcontroller, digital-analog conversion (DAC) circuit and drive circuit in the system. The five parts formed a closed-loop control system based on PID algorithm that was used to control the error between the temperature calculated by the sampling data of ADC and the designed temperature to ensure the stability of the spectrometer's sensor. The experimental results show that, when the operating temperature of sensor is -11°, compared with the original system, the temperature control precision of the new control system is improved from ±0.64° to ±0.04° and the spectrum signal to noise ratio (SNR) is improved from 4891 to 5967.

  19. Sampling procedure and a radio-indicator study of mercury determination in whole blood by using an AMA 254 atomic absorption spectrometer.

    PubMed

    Spevácková, Vera; Korunová, Vlasta; Cejchanová, Mája; Vobecký, Miloslav

    2004-09-01

    A sampling procedure appropriate for the determination of mercury in whole blood was tested by using both inactive controls and a 197Hg mercury radio-indicator. To exclude the influence of the instrumental device (an AMA 254 single-purpose mercury atomic absorption spectrometer) on the determination of mercury in whole blood, the function of the instrument was checked by using rat blood with metabolised 197Hg. The measurement procedure was found to be free of errors. However, the study showed that the material used for the sampling vessels is a crucial parameter for obtaining accurate analytical results. The stability of solutions and samples was tested towards polyethylene (PE) and polypropylene (PP) vessels. PE displayed a time-dependent increase in the mercury content both in the samples and in the blood control material. The probable cause of this increase was direct contamination from the material of the vessel and/or diffusion of mercury from the environment through the vessel walls related to a strong complexing affinity of the sample matrix. This assumption was confirmed by supplying the vessels with the complexing agent Na2EDTA (0.05 mol L(-1)). Commercial PP vessels for blood sampling (Sarstedt S-Monovette Metall Analytik) did not give rise to statistically significant variations in mercury content in the samples and blood control material over a 30-day period.

  20. 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).

  1. 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.

  2. 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).

  3. 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.

  4. Motion Trajectories for Wide-area Surveying with a Rover-based Distributed Spectrometer

    NASA Technical Reports Server (NTRS)

    Tunstel, Edward; Anderson, Gary; Wilson, Edmond

    2006-01-01

    A mobile ground survey application that employs remote sensing as a primary means of area coverage is highlighted. It is distinguished from mobile robotic area coverage problems that employ contact or proximity-based sensing. The focus is on a specific concept for performing mobile surveys in search of biogenic gases on planetary surfaces using a distributed spectrometer -- a rover-based instrument designed for wide measurement coverage of promising search areas. Navigation algorithms for executing circular and spiral survey trajectories are presented for widearea distributed spectroscopy and evaluated based on area covered and distance traveled.

  5. Physiologically Based Absorption Modeling for Amorphous Solid Dispersion Formulations.

    PubMed

    Mitra, Amitava; Zhu, Wei; Kesisoglou, Filippos

    2016-09-06

    Amorphous solid dispersion (ASD) formulations are routinely used to enable the delivery of poorly soluble compounds. This type of formulations can enhance bioavailability due to higher kinetic solubility of the drug substance and increased dissolution rate of the formulation, by the virtue of the fact that the drug molecule exists in the formulation in a high energy amorphous state. In this article we report the application of physiologically based absorption models to mechanistically understand the clinical pharmacokinetics of solid dispersion formulations. Three case studies are shown here to cover a wide range of ASD bioperformance in human and modeling to retrospectively understand their in vivo behavior. Case study 1 is an example of fairly linear PK observed with dose escalation and the use of amorphous solubility to predict bioperformance. Case study 2 demonstrates the development of a model that was able to accurately predict the decrease in fraction absorbed (%Fa) with dose escalation thus demonstrating that such model can be used to predict the clinical bioperformance in the scenario where saturation of absorption is observed. Finally, case study 3 shows the development of an absorption model with the intent to describe the observed incomplete and low absorption in clinic with dose escalation. These case studies highlight the utility of physiologically based absorption modeling in gaining a thorough understanding of ASD performance and the critical factors impacting performance to drive design of a robust drug product that would deliver the optimal benefit to the patients.

  6. A single-board NMR spectrometer based on a software defined radio architecture

    NASA Astrophysics Data System (ADS)

    Tang, Weinan; Wang, Weimin

    2011-01-01

    A single-board software defined radio (SDR) spectrometer for nuclear magnetic resonance (NMR) is presented. The SDR-based architecture, realized by combining a single field programmable gate array (FPGA) and a digital signal processor (DSP) with peripheral radio frequency (RF) front-end circuits, makes the spectrometer compact and reconfigurable. The DSP, working as a pulse programmer, communicates with a personal computer via a USB interface and controls the FPGA through a parallel port. The FPGA accomplishes digital processing tasks such as a numerically controlled oscillator (NCO), digital down converter (DDC) and gradient waveform generator. The NCO, with agile control of phase, frequency and amplitude, is part of a direct digital synthesizer that is used to generate an RF pulse. The DDC performs quadrature demodulation, multistage low-pass filtering and gain adjustment to produce a bandpass signal (receiver bandwidth from 3.9 kHz to 10 MHz). The gradient waveform generator is capable of outputting shaped gradient pulse waveforms and supports eddy-current compensation. The spectrometer directly acquires an NMR signal up to 30 MHz in the case of baseband sampling and is suitable for low-field (<0.7 T) application. Due to the featured SDR architecture, this prototype has flexible add-on ability and is expected to be suitable for portable NMR systems.

  7. A novel aircraft-based tandem mass spectrometer for atmospheric ion and trace gas measurements

    NASA Astrophysics Data System (ADS)

    Moehler, O.; Reiner, Th.; Arnold, F.

    1993-05-01

    The general design and operation of a novel aircraft-based triple-quadrupole mass spectrometer (TQMS) developed for the improved detection and collisional analysis of atmospheric ions and trace gases are described. The instrument is also suitable for laboratory collision-induced dissociation measurements, studies of ion-molecule reactions, and analytical applications. Highly sensitive and selective trace gas detection by chemical ionization mass spectrometry is also possible using a novel ion injection technique. Result of aircraft-based measurements made with the TQMS are summarized.

  8. Research of high power and stable laser in portable Raman spectrometer based on SHINERS technology

    NASA Astrophysics Data System (ADS)

    Cui, Yongsheng; Yin, Yu; Wu, Yulin; Ni, Xuxiang; Zhang, Xiuda; Yan, Huimin

    2013-08-01

    The intensity of Raman light is very weak, which is only from 10-12 to 10-6 of the incident light. In order to obtain the required sensitivity, the traditional Raman spectrometer tends to be heavy weight and large volume, so it is often used as indoor test device. Based on the Shell-Isolated Nanoparticle-Enhanced Raman Spectroscopy (SHINERS) method, Raman optical spectrum signal can be enhanced significantly and the portable Raman spectrometer combined with SHINERS method will be widely used in various fields. The laser source must be stable enough and able to output monochromatic narrow band laser with stable power in the portable Raman spectrometer based on the SHINERS method. When the laser is working, the change of temperature can induce wavelength drift, thus the power stability of excitation light will be affected, so we need to strictly control the working temperature of the laser, In order to ensure the stability of laser power and output current, this paper adopts the WLD3343 laser constant current driver chip of Wavelength Electronics company and MCU P89LPC935 to drive LML - 785.0 BF - XX laser diode(LD). Using this scheme, the Raman spectrometer can be small in size and the drive current can be constant. At the same time, we can achieve functions such as slow start, over-current protection, over-voltage protection, etc. Continuous adjustable output can be realized under control, and the requirement of high power output can be satisfied. Max1968 chip is adopted to realize the accurate control of the laser's temperature. In this way, it can meet the demand of miniaturization. In term of temperature control, integral truncation effect of traditional PID algorithm is big, which is easy to cause static difference. Each output of incremental PID algorithm has nothing to do with the current position, and we can control the output coefficients to avoid full dose output and immoderate adjustment, then the speed of balance will be improved observably. Variable

  9. Self-corrected sensors based on atomic absorption spectroscopy for atom flux measurements in molecular beam epitaxy

    SciTech Connect

    Du, Y. E-mail: scott.chambers@pnnl.gov; Liyu, A. V.; Droubay, T. C.; Chambers, S. A. E-mail: scott.chambers@pnnl.gov; Li, G.

    2014-04-21

    A high sensitivity atom flux sensor based on atomic absorption spectroscopy has been designed and implemented to control electron beam evaporators and effusion cells in a molecular beam epitaxy system. Using a high-resolution spectrometer and a two-dimensional charge coupled device detector in a double-beam configuration, we employ either a non-resonant line or a resonant line with low cross section from the same hollow cathode lamp as the reference for nearly perfect background correction and baseline drift removal. This setup also significantly shortens the warm-up time needed compared to other sensor technologies and drastically reduces the noise coming from the surrounding environment. In addition, the high-resolution spectrometer allows the most sensitive resonant line to be isolated and used to provide excellent signal-to-noise ratio.

  10. Self-corrected sensors based on atomic absorption spectroscopy for atom flux measurements in molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Du, Y.; Droubay, T. C.; Liyu, A. V.; Li, G.; Chambers, S. A.

    2014-04-01

    A high sensitivity atom flux sensor based on atomic absorption spectroscopy has been designed and implemented to control electron beam evaporators and effusion cells in a molecular beam epitaxy system. Using a high-resolution spectrometer and a two-dimensional charge coupled device detector in a double-beam configuration, we employ either a non-resonant line or a resonant line with low cross section from the same hollow cathode lamp as the reference for nearly perfect background correction and baseline drift removal. This setup also significantly shortens the warm-up time needed compared to other sensor technologies and drastically reduces the noise coming from the surrounding environment. In addition, the high-resolution spectrometer allows the most sensitive resonant line to be isolated and used to provide excellent signal-to-noise ratio.

  11. Bolometers as particle spectrometers

    NASA Astrophysics Data System (ADS)

    Stroke, H. H.; Artzner, G.; Coron, N.; Dambier, G.; Hansen, P. G.

    1986-02-01

    A spectrometer based on low-temperature calorimetry has been under development since 1983. The present detector, capable of recording individual alpha and beta particles and X-ray photons, is based on a composite diamond-germanium bolometer. The advantage of a composite bolometer is that it separates the absorption and detection functions. Diamond, as an absorber, is of particular advantage because of its low heat capacity and high thermal diffusivity. The goal is a theoretical energy resolution of a few eV at 0.1 K. Initial experiments at 1.3 K and 0.9 K, which give resolutions in the keV range, are still noise-limited. High-resolution applications, such as in X-ray astronomy and nuclear physics (in particular, neutron mass measurements) are foreseen.

  12. AOTF-based near-infrared imaging spectrometer for rapid identification of camouflaged target

    NASA Astrophysics Data System (ADS)

    Gao, Zhifan; Zeng, Libo; Wu, Qiongshui

    2014-11-01

    Acousto-optic tunable filter (AOTF) is a novel device for spectrometer. The electronic tunability qualifies it with the most compelling advantages of higher wavelength scan rate over the conventional spectrometers that are mechanically tuned, and the feature of large angular aperture makes the AOTF particularly suitable in imaging applications. In this research, an AOTF-based near-infrared imaging spectrometer was developed. The spectrometer consists of a TeO2 AOTF module, a near-infrared imaging lens assembly, an AOTF controller, an InGaAs array detector, an image acquisition card, and a PC. A precisely designed optical wedge is placed at the emergent surface of the AOTF to deal with the inherent dispersion of the TeO2 that may degrade the spatial resolution. The direct digital synthesizer (DDS) techniques and the phase locked loop (PLL) techniques are combined for radio frequency (RF) signal synthesis. The PLL is driven by the DDS to take advantage of both their merits of high frequency resolution, high frequency scan rate and strong spurious signals resistance capability. All the functions relating to wavelength scan, image acquisition, processing, storge and display are controlled by the PC. Calibration results indicate that the spectral range is 898~1670 nm, the spectral resolution is 6.8 nm(@1064 nm), the wavelength separation between frames in the spectral image assembly is 1.0 nm, and the processing time of a single image is less than 1 ms if a TV camera with 640×512 detector is incorporated. A prototype device was assembled to test the capability of differentiating samples with similar appearances, and satisfactory results were achieved. By this device, the chemical compositions and the distribution information can be obtained simultaneously. This system has the most advantages of no moving parts, fast wavelength scan and strong vibration resistance. The proposed imaging spectrometer has a significant application prospect in the area of identification of

  13. [Study of Terahertz Amplitude Imaging Based on the Mean Absorption].

    PubMed

    Zhang, Zeng-yan; Ji, Te; Xiao, Ti-qiao; Zhao, Hong-wei; Chen, Min; Yu, Xiao-han; Tong, Ya-jun; Zhu, Hua-chun; Peng, Wei-wei

    2015-12-01

    A new method of terahertz (THz) imaging based on the mean absorption is proposed. Terahertz radiation is an electromagnetic radiation in the range between millimeter waves and far infrared. THz pulse imaging emerges as a novel tool in many fields because of its low energy and non-ionizing character, such as material, chemical, biological medicine and food safety. A character of THz imaging technique is it can get large amount of information. How to extract the useful parameter from the large amount of information and reconstruct sample's image is a key technology in THz imaging. Some efforts have been done for advanced visualization methods to extract the information of interest from the raw data. Both time domain and frequency domain visualization methods can be applied to extract information on the physical properties of samples from THz imaging raw data. The process of extracting useful parameter from raw data of the new method based on the mean absorption was given in this article. This method relates to the sample absorption and thickness, it delivers good signal to noise ratio in the images, and the dispersion effects are cancelled. A paper with a "THz" shape hole was taken as the sample to do the experiment. Traditional THz amplitude imaging methods in time domain and frequency domain are used to achieve the sample's image, such as relative reduction of pulse maximum imaging method, relative power loss imaging method, and relative power loss at specific frequency imaging method. The sample's information that reflected by these methods and the characteristics of these methods are discussed. The method base on the mean absorption within a certain frequency is also used to reconstruct sample's image. The experimental results show that this new method can well reflect the true information of the sample. And it can achieve a clearer image than the other traditional THz amplitude imaging methods. All the experimental results and theoretical analyses indicate that

  14. Membrane-based absorption of VOCs from a gas stream

    SciTech Connect

    Poddar, T.K.; Majumdar, S.; Sirkar, K.K.

    1996-11-01

    A regenerative absorption-based process was developed for removing VOCs from N{sub 2} in an inert, nonvolatile, organic liquid flowing in compact hollow-fiber devices. The process eliminates flooding, loading, and entrainment, and can replace activated carbon adsorption. Two types of hollow-fiber membranes were studied: one with a microporous wall and the other with a highly VOC-permeable nonporous coating on the outer surface of a microporous hollow fiber. Criteria for nondispersive operation were developed for each case. Experiments were conducted for the absorption of acetone, methylene chloride, toluene, and methanol from the respective VOC-N{sub 2} gas mixture using two absorbents: silicone oil and mineral oil. The highest mass-transfer coefficient was obtained for toluene followed by methylene chloride, acetone, and methanol. Different resistances making up the overall resistance in VOC absorption were characterized comprehensively to develop a predictive capability and compare the absorption performances of two types of fibers and the two absorbents. The absorbent-filled porous membrane contributed significantly to the total mass-transfer resistance. Numerical simulations of governing equations based on a cell model agree well with experimental results.

  15. An injection method for measuring the carbon isotope content of soil carbon dioxide and soil respiration with a tunable diode laser absorption spectrometer.

    PubMed

    Moyes, Andrew B; Schauer, Andrew J; Siegwolf, Rolf T W; Bowling, David R

    2010-04-15

    We present a novel technique in which the carbon isotope ratio (delta(13)C) of soil CO(2) is measured from small gas samples (<5 mL) injected into a stream of CO(2)-free air flowing into a tunable diode laser absorption spectrometer (TDL). This new method extends the dynamic range of the TDL to measure CO(2) mole fractions ranging from ambient to pure CO(2), reduces the volume of sample required to a few mL, and does not require field deployment of the instrument. The measurement precision of samples stored for up to 60 days was 0.23 per thousand. The new TDL method was applied with a simple gas well sampling technique to obtain and measure gas samples from shallow soil depth increments for CO(2) mole fraction and delta(13)C analysis, and subsequent determination of the delta(13)C of soil-respired CO(2). The method was tested using an artificial soil system containing a controlled CO(2) source and compared with an independent method using the TDL and an open soil chamber. The profile and chamber estimates of delta(13)C of an artificially produced CO(2) flux were consistent and converged to the delta(13)C of the CO(2) source at steady state, indicating the accuracy of both methods under controlled conditions. The new TDL method, in which a small pulse of sample is measured on a carrier gas stream, is analogous for the TDL technique to the development of continuous-flow configurations for isotope ratio mass spectrometry. While the applications presented here are focused on soil CO(2), this new TDL method could be applied in a number of situations requiring measurement of delta(13)C of CO(2) in small gas samples with ambient to high CO(2) mole fractions.

  16. X-ray luminescence based spectrometer for investigation of scintillation properties

    SciTech Connect

    Varney, C. R.; Khamehchi, M. A.; Ji, Jianfeng; Selim, F. A.

    2012-10-15

    A new x-ray luminescence based spectrometer was developed and installed to examine the scintillation properties of materials while revealing the origins of luminescence and investigating trapping defects. Measurements were performed on a number of undoped and Ce doped yttrium aluminum garnet crystals and various luminescence centers were characterized. The measured x-ray luminescence spectra provide information about the spectral range and the scintillation efficiency and linearity. The efficiency of charge-carriers production due to x ray, their energy transfer to the luminescence centers, and the efficiency of luminescence are all reflected in the efficiency of x-ray luminescence.

  17. A New Fiber-Optic-Based Phase-Resolved Phosphorescence Spectrometer.

    DTIC Science & Technology

    1988-02-15

    microcomputer employing least-squares programs described elsewhere (24). Reagents and Materials. Anthracene, acridine, phenazine , 7,8-benzoquinoline, and...Resolution. In an effort to more thoroughly evaluate the new fiber-optic-based spectrometer, ternary mixtures of anthracene, phenazine , and acridine were...eq. 2) Value Anthracene 0.094(0.013) 0.096(0.008) 0.09 NO Phenazine 0.321(0.007) 0.317(0.002) - NO Acridine 0.012(0.006) 0.013(0.004) - NO p

  18. "Labrador-Dose" dosimetry system based on a coherent superheterodyne ESR spectrometer

    NASA Astrophysics Data System (ADS)

    Cherepanov, A.; Popova, M.; Tyshchenko, I.; Vakhnin, D.

    2016-09-01

    A new (coherent heterodin) type ESR-spectrometer recently invented in Ural Federal University is described. Application of the spectrometer for measuring high dose ionizing radiation by means of alpha-alanin storage detectors is considered.

  19. Hollow fiber based quantum cascade laser spectrometer for fast and sensitive drug identification

    NASA Astrophysics Data System (ADS)

    Herbst, J.; Scherer, B.; Ruf, A.; Erb, J.; Lambrecht, A.

    2012-01-01

    Sensitive and fast identification of drugs or drug precursors is important and necessary in scenarios like baggage or container check by customs or police. Fraunhofer IPM is developing a laser spectrometer using external cavity quantum cascade lasers (EC-QCL) to obtain mid-infrared (IR) absorption spectra in the wavelength range of the specific vibrational bands of amphetamines and their precursors. The commercial EC-QCL covers a tuning range of about 225 cm-1 within 1.4 s. The system could be used for different sample types like bulk samples or liquid solutions. A sampling unit evaporates the sample. Because of small sample amounts a 3 m long hollow fiber with an inner volume smaller than 1ml is used as gas cell and wave guide for the laser beam. This setup is suitable as a detector of a gas chromatograph instead of a standard detector (TCD or FID). The advantage is the selective identification of drugs by their IR spectra in addition to the retention time in the gas chromatographic column. In comparison to Fourier Transform IR systems the EC-QCL setup shows a good mechanical robustness and has the advantage of a point light source. Because of the good fiber incoupling performance of the EC-QCL it is possible to use hollow fibers. So, a good absorption signal is achieved because of the long optical path in the small cell volume without significant dilution. In first laboratory experiments a detection limit in the microgram range for pseudo ephedrine is achieved.

  20. Mobile phone based mini-spectrometer for rapid screening of skin cancer

    NASA Astrophysics Data System (ADS)

    Das, Anshuman; Swedish, Tristan; Wahi, Akshat; Moufarrej, Mira; Noland, Marie; Gurry, Thomas; Aranda-Michel, Edgar; Aksel, Deniz; Wagh, Sneha; Sadashivaiah, Vijay; Zhang, Xu; Raskar, Ramesh

    2015-06-01

    We demonstrate a highly sensitive mobile phone based spectrometer that has potential to detect cancerous skin lesions in a rapid, non-invasive manner. Earlier reports of low cost spectrometers utilize the camera of the mobile phone to image the field after moving through a diffraction grating. These approaches are inherently limited by the closed nature of mobile phone image sensors and built in optical elements. The system presented uses a novel integrated grating and sensor that is compact, accurate and calibrated. Resolutions of about 10 nm can be achieved. Additionally, UV and visible LED excitation sources are built into the device. Data collection and analysis is simplified using the wireless interfaces and logical control on the smart phone. Furthermore, by utilizing an external sensor, the mobile phone camera can be used in conjunction with spectral measurements. We are exploring ways to use this device to measure endogenous fluorescence of skin in order to distinguish cancerous from non-cancerous lesions with a mobile phone based dermatoscope.

  1. Nitric oxide isotopic analyzer based on a compact dual-modulation Faraday rotation spectrometer.

    PubMed

    Zhang, Eric; Huang, Stacey; Ji, Qixing; Silvernagel, Michael; Wang, Yin; Ward, Bess; Sigman, Daniel; Wysocki, Gerard

    2015-10-14

    We have developed a transportable spectroscopic nitrogen isotopic analyzer. The spectrometer is based on dual-modulation Faraday rotation spectroscopy of nitric oxide isotopologues with near shot-noise limited performance and baseline-free operation. Noise analysis indicates minor isotope ((15)NO) detection sensitivity of 0.36 ppbv·Hz(-1/2), corresponding to noise-equivalent Faraday rotation angle (NEA) of 1.31 × 10(-8) rad·Hz(-1/2) and noise-equivalent absorbance (αL)min of 6.27 × 10(-8) Hz(-1/2). White-noise limited performance at 2.8× the shot-noise limit is observed up to ~1000 s, allowing reliable calibration and sample measurement within the drift-free interval of the spectrometer. Integration with wet-chemistry based on acidic vanadium(III) enables conversion of aqueous nitrate/nitrite samples to gaseous NO for total nitrogen isotope analysis. Isotopic ratiometry is accomplished via time-multiplexed measurements of two NO isotope transitions. For 5 μmol potassium nitrate samples, the instrument consistently yields ratiometric precision below 0.3‰, thus demonstrating potential as an in situ diagnostic tool for environmental nitrogen cycle studies.

  2. Nitric Oxide Isotopic Analyzer Based on a Compact Dual-Modulation Faraday Rotation Spectrometer

    PubMed Central

    Zhang, Eric; Huang, Stacey; Ji, Qixing; Silvernagel, Michael; Wang, Yin; Ward, Bess; Sigman, Daniel; Wysocki, Gerard

    2015-01-01

    We have developed a transportable spectroscopic nitrogen isotopic analyzer. The spectrometer is based on dual-modulation Faraday rotation spectroscopy of nitric oxide isotopologues with near shot-noise limited performance and baseline-free operation. Noise analysis indicates minor isotope (15NO) detection sensitivity of 0.36 ppbv·Hz−1/2, corresponding to noise-equivalent Faraday rotation angle (NEA) of 1.31 × 10−8 rad·Hz−1/2 and noise-equivalent absorbance (αL)min of 6.27 × 10−8 Hz−1/2. White-noise limited performance at 2.8× the shot-noise limit is observed up to ~1000 s, allowing reliable calibration and sample measurement within the drift-free interval of the spectrometer. Integration with wet-chemistry based on acidic vanadium(III) enables conversion of aqueous nitrate/nitrite samples to gaseous NO for total nitrogen isotope analysis. Isotopic ratiometry is accomplished via time-multiplexed measurements of two NO isotope transitions. For 5 μmol potassium nitrate samples, the instrument consistently yields ratiometric precision below 0.3‰, thus demonstrating potential as an in situ diagnostic tool for environmental nitrogen cycle studies. PMID:26473876

  3. High resolution TE&TM near infrared compact spectrometer based on waveguide grating structures

    NASA Astrophysics Data System (ADS)

    Martin, G.; Thomas, F.; Heidmann, S.; de Mengin, M.; Courjal, N.; Ulliac, G.; Morand, A.; Benech, P.; Kern, P.; Le Coarer, E...

    2015-05-01

    Integrated optics spectrometers can be essentially classified into two main families: based on Fourier transform or dispersed modes. In the first case, an interferogram generated inside an optical waveguide is sampled using nanodetectors, these scatter light into the detector that is in contact with the waveguide. A dedicated FFT processing is needed in order to recover the spectrum with high resolution but limited spectral range. Another way is to extract the optical signal confined in a waveguide using a surface grating and directly obtain the spectrum by means of a relay optics that generates the spectrum on the Fourier plane of the lens, where the detector is placed. Following this second approach, we present a high-resolution compact dispersive spectrometer (δλ =1.5nm at λ=1050nm) based on guided optics technology. The propagating signal is dispersed out of a waveguide thanks to a surface grating that lays along it. Focused Ion Beam technique is used to etch nano-grooves that act as individual scattering centers and constitute the surface grating along the waveguide. The waveguide is realized using X-cut, Ypropagating Lithium Niobate substrate, where the effective index for TE and TM guided modes is different. This results in a strong angular separation of TE and TM diffracted modes, allowing simultaneous detection of spectra for both polarizations. A simple relay optics, with limited optical aberrations, reimages the diffracted signal on the focal plane array, leading to a robust, easy to align instrument.

  4. Mass-specific optical absorption coefficients and imaginary part of the complex refractive indices of mineral dust components measured by a multi-wavelength photoacoustic spectrometer

    NASA Astrophysics Data System (ADS)

    Utry, N.; Ajtai, T.; Pintér, M.; Tombácz, E.; Illés, E.; Bozóki, Z.; Szabó, G.

    2015-01-01

    Mass-specific optical absorption coefficients (MACs) and the imaginary part (κ) of the refractive indices of various mineral dust components including silicate clays (illite, kaolin and bentonite), oxides (quartz, hematite and rutile), and carbonate (limestone) were determined at the wavelengths of 1064, 532, 355 and 266 nm. The MAC values were calculated from aerosol optical absorption coefficients measured by a multi-wavelength photoacoustic (PA) instrument, the mass concentration and the number size distribution of the generated aerosol samples as well as the size transfer functions of the measuring instruments. Values of κ were calculated from the measured and particle-loss-corrected data by using a Mie-theory-based retrieval algorithm. The determined values could be used for comparisons with calculated wavelength-dependent κ values typically deduced from bulk-phase measurements by using indirect measurement methods. Accordingly, the presented comparison of the measured and calculated aerosol optical absorption spectra revealed the strong need for standardized sample preparation and measurement methodology in case of bulk-phase measurements.

  5. 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.

  6. [Study on the absorption spectrum properties of flexible black silicon doped with sulfur and fluorine based on first-principles].

    PubMed

    Wei, Wei; Zhu, Yong; Lin, Cheng; Tian, Li; Xu, Zu-Wen; Nong, Jin-Peng

    2014-04-01

    It is quite urgent to need a flexible photodetector in the ultraviolet-visible-near infrared region for building a miniaturization broadband spectrometer. In the present paper, one kind of flexible black silicon doped with sulfur and fluorine was proposed and the optical absorption spectrum was investigated in broadband region. Firstly, the electronic structure, band structure and the optical absorption properties of the flexible black silicon doped with sulfur and fluoride were calculated using the first-principles pseudo potential calculations based on density-functional theory. Then, the absorption spectrum model of the flexible black silicon was built based on both the first-principles and finite domain time difference method. The results show that the cut-off wavelength has a red shift as the band gap of doped material becomes narrower. The higher the doping concentration is, the higher the optical absorption coefficient is obtained. The absorption coefficient of flexible black silicon doped with 50% sulfur is 8.3 times higher than that of 1.5% sulfur doping sample at the wavelength of 1 500 nm while the ratio turns to be 3 times when doped with 50% and 1.5% fluoride. The black silicon with small-size surface microstructure has the highest absorptance in the near-infrared region at the same doping concentration of 50%. Finally, a sample of flexible black silicon was fabricated by the femtosecond laser auto scanning system. The test results indicate that the absorptance of the sample is higher than 95% both in the ultraviolet and visible region and is fluctuated from 70% to 80% in the near-infrared region. It shows that as a novel light-absorbing material in broadband region the flexible black silicon doped with Sulfur and Fluorine has an potential application in exploring miniaturization broadband spectroscopy.

  7. Ground based NO2 and O3 measurements by visible spectrometer at Syowa Base (69 deg S), Antarctica

    NASA Technical Reports Server (NTRS)

    Kondo, Y.; Matthews, W. A.; Johnston, Paul V.; Hayashi, M.; Koike, M.; Iwasaka, Y.; Shimizu, A.; Budiyono, A.; Yamanouchi, T.; Aoki, S.

    1994-01-01

    The column amounts of NO2 and ozone have been measured using visible spectroscopy at Syowa Base (69 deg S) since March 1990. Ozone was also measured at the same location with a Dobson spectrometer as well as ozonesondes being flown regularly. The characteristic features of the seasonal and diurnal variations of NO2 are presented. The column ozone values from the visible spectrometers are compared with the Dobson data. The very low values of NO2 in midwinter and early spring are consistent with the conditions predicted to be needed for heterogeneous ozone destruction in early spring. In late spring and summer of 1991, NO2 amounts were considerably smaller than in 1990, presumably due to the effect of Mt. Pinatubo eruption.

  8. A high resolution gamma-ray spectrometer based on superconducting microcalorimeters

    SciTech Connect

    Bennett, D. A.; Horansky, R. D.; Schmidt, D. R.; Doriese, W. B.; Fowler, J. W.; Kotsubo, V.; Mates, J. A. B.; Hoover, A. S.; Winkler, R.; Rabin, M. W.; Alpert, B. K.; Beall, J. A.; Fitzgerald, C. P.; Hilton, G. C.; Irwin, K. D.; O'Neil, G. C.; Reintsema, C. D.; Schima, F. J.; Swetz, D. S.; Vale, L. R.; and others

    2012-09-15

    Improvements in superconductor device fabrication, detector hybridization techniques, and superconducting quantum interference device readout have made square-centimeter-sized arrays of gamma-ray microcalorimeters, based on transition-edge sensors (TESs), possible. At these collecting areas, gamma microcalorimeters can utilize their unprecedented energy resolution to perform spectroscopy in a number of applications that are limited by closely-spaced spectral peaks, for example, the nondestructive analysis of nuclear materials. We have built a 256 pixel spectrometer with an average full-width-at-half-maximum energy resolution of 53 eV at 97 keV, a useable dynamic range above 400 keV, and a collecting area of 5 cm{sup 2}. We have demonstrated multiplexed readout of the full 256 pixel array with 236 of the pixels (91%) giving spectroscopic data. This is the largest multiplexed array of TES microcalorimeters to date. This paper will review the spectrometer, highlighting the instrument design, detector fabrication, readout, operation of the instrument, and data processing. Further, we describe the characterization and performance of the newest 256 pixel array.

  9. Configurable-bandwidth imaging spectrometer based on an acousto-optic tunable filter

    NASA Astrophysics Data System (ADS)

    Vila-Francés, Joan; Calpe-Maravilla, Javier; Muñoz-Mari, Jordi; Gómez-Chova, Luis; Amorós-López, Julia; Ribes-Gómez, Emilio; Durán-Bosch, Vicente

    2006-07-01

    This article presents a new imaging spectrometer called autonomous tunable filtering system. The instrument acquires sequential images at different spectral wavelengths in the visible and near infrared range of the electromagnetic spectrum. The spectral selection is performed by an acousto-optic tunable filter (AOTF), which is driven by a custom radio-frequency (rf) generator based on a direct digital synthesizer (DDS). The DDS allows a high flexibility in terms of acquisition speed and bandwidth selection. The rf power is dynamically controlled to drive the AOTF with the optimum value for each wavelength. The images are formed through a carefully designed optical layout and acquired with a high performance digital camera. The application software controls the instrument and acquires the raw spectral images from the camera. This software optionally corrects the image for the AOTF nonidealities, such as diffraction efficiency variations, spatial nonuniformity, and chromatic aberration, and generates a single multiband image file. Moreover, the software can calculate the reflectance or transmittance of the acquired images. The instrument has been calibrated to give precise and repetitive measurements and has been validated against a high performance point spectrometer. As a case example, the instrument has been successfully used for the mapping of chlorophyll content of plant leaves from their multispectral reflectance images.

  10. Design and evaluation of a fast Fourier transform-based nonlinear dielectric spectrometer

    NASA Astrophysics Data System (ADS)

    Treo, Ernesto F.; Felice, Carmelo J.

    2009-11-01

    Nonlinear dielectric spectroscopy of micro-organism is carried out by applying a moderate electrical field to an aqueous sample through two metal electrodes. Several ad hoc nonlinear spectrometers were proposed in the literature. However, these designs barely compensated the nonlinear distortion derived from the electrode-electrolyte interfaces (EEI). Moreover, the contribution of the suspension is masked by the effect of the nonlinearity introduced by the electrode contacts. Conversely, the nonlinear capability of a commercial tetrapolar analyzer has not been fully investigated. In this paper a new nonlinear tetrapolar spectrometer is proposed based on a commercial linear apparatus and ad hoc control and signal processing software. The system was evaluated with discrete electronic phantoms and showed that it can measure nonlinear properties of aqueous suspension independently of the presence of EEI (ANOVA test, p >0.001). It was also tested with real aqueous samples. The harmonics observed in the current that circulates through the sample reveals useful information about the transfer function of the sample. The total harmonic distortion was computed for linear mediums. Values lower than -60 dB suggest that the system has enough capability to perform nonlinear microbiological analysis. Design specifications, sources of interference, and equipment's limitations are discussed.

  11. 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.

  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. Cascaded process model based control: packed absorption column application.

    PubMed

    Govindarajan, Anand; Jayaraman, Suresh Kumar; Sethuraman, Vijayalakshmi; Raul, Pramod R; Rhinehart, R Russell

    2014-03-01

    Nonlinear, adaptive, process-model based control is demonstrated in a cascaded single-input-single-output mode for pressure drop control in a pilot-scale packed absorption column. The process is shown to be nonlinear. Control is demonstrated in both servo and regulatory modes, for no wind-up in a constrained situation, and for bumpless transfer. Model adaptation is demonstrated and shown to provide process insight. The application procedure is revealed as a design guide to aid others in implementing process-model based control.

  14. Tunable vacuum ultraviolet laser based spectrometer for angle resolved photoemission spectroscopy

    NASA Astrophysics Data System (ADS)

    Jiang, Rui; Mou, Daixiang; Wu, Yun; Huang, Lunan; McMillen, Colin D.; Kolis, Joseph; Giesber, Henry G.; Egan, John J.; Kaminski, Adam

    2014-03-01

    We have developed an angle-resolved photoemission spectrometer with tunable vacuum ultraviolet laser as a photon source. The photon source is based on the fourth harmonic generation of a near IR beam from a Ti:sapphire laser pumped by a CW green laser and tunable between 5.3 eV and 7 eV. The most important part of the set-up is a compact, vacuum enclosed fourth harmonic generator based on potassium beryllium fluoroborate crystals, grown hydrothermally in the US. This source can deliver a photon flux of over 1014 photon/s. We demonstrate that this energy range is sufficient to measure the kz dispersion in an iron arsenic high temperature superconductor, which was previously only possible at synchrotron facilities.

  15. Tunable vacuum ultraviolet laser based spectrometer for angle resolved photoemission spectroscopy

    SciTech Connect

    Jiang, Rui; Mou, Daixiang; Wu, Yun; Huang, Lunan; Kaminski, Adam; McMillen, Colin D.; Kolis, Joseph; Giesber, Henry G.; Egan, John J.

    2014-03-15

    We have developed an angle-resolved photoemission spectrometer with tunable vacuum ultraviolet laser as a photon source. The photon source is based on the fourth harmonic generation of a near IR beam from a Ti:sapphire laser pumped by a CW green laser and tunable between 5.3 eV and 7 eV. The most important part of the set-up is a compact, vacuum enclosed fourth harmonic generator based on potassium beryllium fluoroborate crystals, grown hydrothermally in the US. This source can deliver a photon flux of over 10{sup 14} photon/s. We demonstrate that this energy range is sufficient to measure the k{sub z} dispersion in an iron arsenic high temperature superconductor, which was previously only possible at synchrotron facilities.

  16. Measurements of ambient ammonia using a tunable diode laser absorption spectrometer: Characteristics of ambient ammonia emissions in an urban area of New York City

    NASA Astrophysics Data System (ADS)

    Li, Yongquan; Schwab, James J.; Demerjian, Kenneth L.

    2006-05-01

    A tunable diode laser absorption spectrometer (TDLAS) was deployed during the PMTACS-NY Supersite winter 2004 intensive field campaign at Queens College in New York City to measure the ambient gaseous ammonia. For the characterization of ammonia emissions from the mobile sources, a LI-7000 CO2/H2O analyzer was also collocated with the TDLAS to measure ambient CO2 and H2O vapor. The field measurements and laboratory calibration with certified ammonia standard have been used to evaluate the performance of the TDLAS system. High time resolved TDLAS ambient ammonia measurements performed at Queens College from 10 January to 6 February showed high variability, with NH3 concentrations ranging from below the detection limit (0.1 ppb) to maxima of 197.4 ppb and a mean value of 0.8 ppb over the entire campaign. Many high-frequency NH3 spikes spanning over a less than 1-min duration were observed during the high traffic periods. The occurrence of the NH3 spikes was closely correlated with observed CO2 spikes, a good marker of traffic exhaust. This correlation yielded an NH3 emission ratio of 0.12 ppbv/ppmv, which can be used to estimate an NH3 emission factor of 35.5 mg/km. The [NH3]/[CO2] ratios over the entire field study was also obtained and added into the best NH3 emission estimates. On a snowy day, no obvious drop of NH3 and CO2 concentrations was measured as the ambient H2O vapor increased. The observed dramatic decrease in the ambient NH3 and CO2 concentrations on a rainy day resulted from a quick air mass switch. Two similar bimodal diurnal patterns associated with the rush hour traffic were observed during school holidays and school days of Queens College, New York. More NH3 emissions from cold start vehicles might contribute to a higher peak in the late afternoon hours. Such observations suggest that the NH3 emissions from the traffic exhaust could be a major source of the ambient NH3 in urban areas.

  17. A Fabry-Perot interferometer-based long-wavelength infrared spectrometer utilizing a novel PDMS patterning technique

    NASA Astrophysics Data System (ADS)

    Geon Jung, Dong; Kim, Ho Won; Baek, Sun Min; Bang, Soon Jae; Kong, Seong Ho

    2015-06-01

    We report a Fabry-Perot interferometer (FPI)-based infrared (IR) spectrometer designed for long-wavelength infrared (LWIR) region. To fabricate the proposed FPI-based LWIR spectrometer, we developed a novel poly(dimethylsiloxane) (PDMS) patterning technique by combining photolithography and dry etching. The proposed PDMS patterning technique has advantages such as clear shape of PDMS pattern and no damage to the silicon (Si) substrate. Especially, the final height of PDMS pattern is easily adjusted by controlling the thickness of spin-coated photoresist. The proposed FPI-based IR spectrometer, which is composed of upper and lower substrate were fabricated separately utilizing newly proposed PDMS patterning technique. Experimental results show that maximum transmittance of filtered wavelength component by the proposed FPI-based IR spectrometer lies at the wavelength of 16 µm. The proposed IR spectrometer can detect a specific wavelength at LWIR region by controlling the air etalon gap that is adjusted by utilizing the proposed PDMS patterning technique.

  18. 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.

  19. Wireless, low-cost, FPGA-based miniature gamma ray spectrometer

    NASA Astrophysics Data System (ADS)

    Becker, E. M.; Farsoni, A. T.

    2014-10-01

    A compact, low-cost, wireless gamma-ray spectrometer is a tool sought by a number of different organizations in the field of radiation detection. Such a device has applications in emergency response, battlefield assessment, and personal dosimetry. A prototype device fitting this description has been constructed in the Advanced Radiation Instrumentation Laboratory at Oregon State University. The prototype uses a CsI(Tl) scintillator coupled to a solid-state photomultiplier and a 40 MHz, 12-bit, FPGA-based digital pulse processor to measure gamma radiation, and is able to be accessed wirelessly by mobile phone. The prototype device consumes roughly 420 mW, weighs about 28 g (not including battery), and measures 2.54×3.81 cm2. The prototype device is able to achieve 5.9% FWHM energy resolution at 662 keV.

  20. Ambient formaldehyde detection with a laser spectrometer based on difference-frequency generation in PPLN

    NASA Technical Reports Server (NTRS)

    Rehle, D.; Leleux, D.; Erdelyi, M.; Tittel, F.; Fraser, M.; Friedfeld, S.

    2001-01-01

    A laser spectrometer based on difference-frequency generation in periodically poled LiNbO3 (PPLN) has been used to quantify atmospheric formaldehyde with a detection limit of 0.32 parts per billion in a given volume (ppbV) using specifically developed data-processing techniques. With state-of-the-art fiber-coupled diode-laser pump sources at 1083 nm and 1561 nm, difference-frequency radiation has been generated in the 3.53-micrometers (2832-cm-1) spectral region. Formaldehyde in ambient air in the 1- to 10-ppb V range has been detected continuously for nine and five days at two separate field sites in the Greater Houston area operated by the Texas Natural Resource Conservation Commission (TNRCC) and the Houston Regional Monitoring Corporation (HRM). The acquired spectroscopic data are compared with results obtained by a well-established wet-chemical o-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine (PFBHA) technique.

  1. A new direct absorption tunable diode laser spectrometer for high precision measurement of water vapor in the upper troposphere and lower stratosphere

    NASA Astrophysics Data System (ADS)

    Sargent, M. R.; Sayres, D. S.; Smith, J. B.; Witinski, M.; Allen, N. T.; Demusz, J. N.; Rivero, M.; Tuozzolo, C.; Anderson, J. G.

    2013-07-01

    We present a new instrument for the measurement of water vapor in the upper troposphere and lower stratosphere (UT/LS), the Harvard Herriott Hygrometer (HHH). HHH employs a tunable diode near-IR laser to measure water vapor via direct absorption in a Herriott cell. The direct absorption technique provides a direct link between the depth of the observed absorption line and the measured water vapor concentration, which is calculated based on spectroscopic parameters in the HITRAN database. While several other tunable diode laser (TDL) instruments have been used to measure water vapor in the UT/LS, HHH is set apart by its use of an optical cell an order of magnitude smaller than those of other direct absorption TDLs in operation, allowing for a more compact, lightweight instrument. HHH is also unique in its integration into a common duct with the Harvard Lyman-α hygrometer, an independent photo-fragment fluorescence instrument which has been thoroughly validated over 19 years of flight measurements. The instrument was flown for the first time in the Mid-latitude Airborne Cirrus Properties Experiment (MACPEX) on NASA's WB-57 aircraft in spring, 2011, during which it demonstrated in-flight precision of 0.1 ppmv (1 s) with 1-sigma uncertainty of 5% ± 0.7 ppmv. Since the campaign, changes to the instrument have lead to improved accuracy of 5% ± 0.2 ppmv as demonstrated in the laboratory. During MACPEX, HHH successfully measured water vapor at concentrations from 3.5 to 600 ppmv in the upper troposphere and lower stratosphere. HHH and Lyman-α, measuring independently but under the same sampling conditions, agreed on average to within 1% at water vapor mixing ratios above 20 ppmv and to within 0.3 ppmv at lower mixing ratios. HHH also agreed with a number of other in situ water vapor instruments on the WB-57 to within their stated uncertainties, and to within 0.7 ppmv at low water. This agreement constitutes a significant improvement over past in situ comparisons, in

  2. A new direct absorption tunable diode laser spectrometer for high precision measurement of water vapor in the upper troposphere and lower stratosphere.

    PubMed

    Sargent, M R; Sayres, D S; Smith, J B; Witinski, M; Allen, N T; Demusz, J N; Rivero, M; Tuozzolo, C; Anderson, J G

    2013-07-01

    We present a new instrument for the measurement of water vapor in the upper troposphere and lower stratosphere (UT∕LS), the Harvard Herriott Hygrometer (HHH). HHH employs a tunable diode near-IR laser to measure water vapor via direct absorption in a Herriott cell. The direct absorption technique provides a direct link between the depth of the observed absorption line and the measured water vapor concentration, which is calculated based on spectroscopic parameters in the HITRAN database. While several other tunable diode laser (TDL) instruments have been used to measure water vapor in the UT∕LS, HHH is set apart by its use of an optical cell an order of magnitude smaller than those of other direct absorption TDLs in operation, allowing for a more compact, lightweight instrument. HHH is also unique in its integration into a common duct with the Harvard Lyman-α hygrometer, an independent photo-fragment fluorescence instrument which has been thoroughly validated over 19 years of flight measurements. The instrument was flown for the first time in the Mid-latitude Airborne Cirrus Properties Experiment (MACPEX) on NASA's WB-57 aircraft in spring, 2011, during which it demonstrated in-flight precision of 0.1 ppmv (1 s) with 1-sigma uncertainty of 5% ± 0.7 ppmv. Since the campaign, changes to the instrument have lead to improved accuracy of 5% ± 0.2 ppmv as demonstrated in the laboratory. During MACPEX, HHH successfully measured water vapor at concentrations from 3.5 to 600 ppmv in the upper troposphere and lower stratosphere. HHH and Lyman-α, measuring independently but under the same sampling conditions, agreed on average to within 1% at water vapor mixing ratios above 20 ppmv and to within 0.3 ppmv at lower mixing ratios. HHH also agreed with a number of other in situ water vapor instruments on the WB-57 to within their stated uncertainties, and to within 0.7 ppmv at low water. This agreement constitutes a significant improvement over past in situ comparisons

  3. Oil Spill Detection along the Gulf of Mexico Coastline based on Airborne Imaging Spectrometer Data

    NASA Astrophysics Data System (ADS)

    Arslan, M. D.; Filippi, A. M.; Guneralp, I.

    2013-12-01

    The Deepwater Horizon oil spill in the Gulf of Mexico between April and July 2010 demonstrated the importance of synoptic oil-spill monitoring in coastal environments via remote-sensing methods. This study focuses on terrestrial oil-spill detection and thickness estimation based on hyperspectral images acquired along the coastline of the Gulf of Mexico. We use AVIRIS (Airborne Visible/Infrared Imaging Spectrometer) imaging spectrometer data collected over Bay Jimmy and Wilkinson Bay within Barataria Bay, Louisiana, USA during September 2010. We also employ field-based observations of the degree of oil accumulation along the coastline, as well as in situ measurements from the literature. As part of our proposed spectroscopic approach, we operate on atmospherically- and geometrically-corrected hyperspectral AVIRIS data to extract image-derived endmembers via Minimum Noise Fraction transform, Pixel Purity Index-generation, and n-dimensional visualization. Extracted endmembers are then used as input to endmember-mapping algorithms to yield fractional-abundance images and crisp classification images. We also employ Multiple Endmember Spectral Mixture Analysis (MESMA) for oil detection and mapping in order to enable the number and types of endmembers to vary on a per-pixel basis, in contast to simple Spectral Mixture Analysis (SMA). MESMA thus better allows accounting for spectral variabiltiy of oil (e.g., due to varying oil thicknesses, states of degradation, and the presence of different oil types, etc.) and other materials, including soils and salt marsh vegetation of varying types, which may or may not be affected by the oil spill. A decision-tree approach is also utilized for comparison. Classification results do indicate that MESMA provides advantageous capabilities for mapping several oil-thickness classes for affected vegetation and soils along the Gulf of Mexico coastline, relative to the conventional approaches tested. Oil thickness-mapping results from MESMA

  4. TDL based spectrometer for simultaneously monitoring local and column greenhouse gases

    NASA Astrophysics Data System (ADS)

    Klimchuk, A., Sr.; Semenov, V.

    2015-12-01

    In this paper we present a concept of TDL based spectrometer for local and column greenhouse gases monitoring in particular for CO2, CH4, N2O and O2. The optical scheme of spectrometer's single gas monitoring channel is shown on the figure 1 for CO2 as an example. For each gas monitoring laser radiation is divided into four channels.One of the channels is used for monitoring CO2 abundance in the local atmosphere. This channel is presented by off-axis integrated cavity output spectroscopy (OA ICOS). Mirrors with reflection coefficient R~99.99% are used in order to achieve effective optical path equal to 1500 meters for high precision CO2 monitoring. Measurements will be conducted at a pressure of 100 milibar and a compact diaphragm pump will be used. Reference gas spectra will be used for diode laser frequency stabilization. These spectra will be recorded in specified channel, which is also based on OA ICOS technique. Mirrors reflection coefficients are equal to ~99% in this case. A frequency scale calibration will be provided by Fabry-Perot (FP) ethanol in third channel. The same FP-ethanol will be used for each gas measurements. The last channel is presented by heterodyne spectroscopy and will be used for average column and vertical profiling measurements of greenhouse gases. The intermediate frequency bandwidth is 10 MHz. The spectral coverage is provided by laser wavelength sweep with 100 kHz frequency. Signal registration will be carried out by high-speed electronics without principal nonlinear elements in analog signal path. Present concept incorporates channels for local and column monitoring of CO2 (1.605μ), CH4 (1.65μ), O2 (1.27μ), N2O (2.25μ) and can be easily extended to H2O (1.39μ), CO (2.33μ), etc. measurements.

  5. Comparative study on three highly sensitive absorption measurement techniques characterizing lithium niobate over its entire transparent spectral range.

    PubMed

    Leidinger, M; Fieberg, S; Waasem, N; Kühnemann, F; Buse, K; Breunig, I

    2015-08-24

    We employ three highly sensitive spectrometers: a photoacoustic spectrometer, a photothermal common-path interferometer and a whispering-gallery-resonator-based absorption spectrometer, for a comparative study of measuring the absorption coefficient of nominally transparent undoped, congruently grown lithium niobate for ordinarily and extraordinarily polarized light in the wavelength range from 390 to 3800 nm. The absorption coefficient ranges from below 10(-4) cm(-1) up to 2 cm(-1). Furthermore, we measure the absorption at the Urbach tail as well as the multiphonon edge of the material by a standard grating spectrometer and a Fourier-transform infrared spectrometer, providing for the first time an absorption spectrum of the whole transparency window of lithium niobate. The absorption coefficients obtained by the three highly sensitive and independent methods show good agreement.

  6. Design of thin-film filters for resolution improvements in filter-array based spectrometers using DSP

    NASA Astrophysics Data System (ADS)

    Lee, Woong-Bi; Kim, Cheolsun; Ju, Gun Wu; Lee, Yong Tak; Lee, Heung-No

    2016-05-01

    Miniature spectrometers have been widely developed in various academic and industrial applications such as bio-medical, chemical and environmental engineering. As a family of spectrometers, optical filter-array based spectrometers fabricated using CMOS or Nano technology provide miniaturization, superior portability and cost effectiveness. In filterarray based spectrometers, the resolution which represents the ability how closely resolve two neighboring spectra, depends on the number of filters and the characteristics of the transmission functions (TFs) of the filters. In practice, due to the small-size and low-cost fabrication, the number of filters is limited and the shape of the TF of each filter is nonideal. As a development of modern digital signal processing (DSP), the spectrometers are equipped with DSP algorithms not only to alleviate distortions due to unexpected noise or interferences among filters but also reconstruct the original signal spectrum. For a high-resolution spectrum reconstruction by the DSP, the TFs of the filters need to be sufficiently uncorrelated with each other. In this paper, we present a design of optical thin-film filters which have the uncorrelated TFs. Each filter consists of multiple layers of high- and low-refractive index materials deposited on a substrate. The proposed design helps the DSP algorithm to improve resolution with a small number of filters. We demonstrate that a resolution of 5 nm within a range from 500 nm to 1100 nm can be achieved with only 64 filters.

  7. Spectral Similarity Assessment Based on a Spectrum Reflectance-Absorption Index and Simplified Curve Patterns for Hyperspectral Remote Sensing.

    PubMed

    Ma, Dan; Liu, Jun; Huang, Junyi; Li, Huali; Liu, Ping; Chen, Huijuan; Qian, Jing

    2016-01-26

    Hyperspectral images possess properties such as rich spectral information, narrow bandwidth, and large numbers of bands. Finding effective methods to retrieve land features from an image by using similarity assessment indices with specific spectral characteristics is an important research question. This paper reports a novel hyperspectral image similarity assessment index based on spectral curve patterns and a reflection-absorption index. First, some spectral reflection-absorption features are extracted to restrict the subsequent curve simplification. Then, the improved Douglas-Peucker algorithm is employed to simplify all spectral curves without setting the thresholds. Finally, the simplified curves with the feature points are matched, and the similarities among the spectral curves are calculated using the matched points. The Airborne Visible Infrared Imaging Spectrometer (AVIRIS) and Reflective Optics System Imaging Spectrometer (ROSIS) hyperspectral image datasets are then selected to test the effect of the proposed index. The practical experiments indicate that the proposed index can achieve higher precision and fewer points than the traditional spectral information divergence and spectral angle match.

  8. Spectral Similarity Assessment Based on a Spectrum Reflectance-Absorption Index and Simplified Curve Patterns for Hyperspectral Remote Sensing

    PubMed Central

    Ma, Dan; Liu, Jun; Huang, Junyi; Li, Huali; Liu, Ping; Chen, Huijuan; Qian, Jing

    2016-01-01

    Hyperspectral images possess properties such as rich spectral information, narrow bandwidth, and large numbers of bands. Finding effective methods to retrieve land features from an image by using similarity assessment indices with specific spectral characteristics is an important research question. This paper reports a novel hyperspectral image similarity assessment index based on spectral curve patterns and a reflection-absorption index. First, some spectral reflection-absorption features are extracted to restrict the subsequent curve simplification. Then, the improved Douglas-Peucker algorithm is employed to simplify all spectral curves without setting the thresholds. Finally, the simplified curves with the feature points are matched, and the similarities among the spectral curves are calculated using the matched points. The Airborne Visible Infrared Imaging Spectrometer (AVIRIS) and Reflective Optics System Imaging Spectrometer (ROSIS) hyperspectral image datasets are then selected to test the effect of the proposed index. The practical experiments indicate that the proposed index can achieve higher precision and fewer points than the traditional spectral information divergence and spectral angle match. PMID:26821030

  9. The Berkeley tunable far infrared laser spectrometers

    NASA Technical Reports Server (NTRS)

    Blake, G. A.; Laughlin, K. B.; Cohen, R. C.; Busarow, K. L.; Gwo, D.-H.

    1991-01-01

    A detailed description is presented for a tunable far infrared laser spectrometer based on frequency mixing of an optically pumped molecular gas laser with tunable microwave radiation in a Schottky point contact diode. The system has been operated on over 30 laser lines in the range 10-100/cm and exhibits a maximum absorption sensitivity near one part in a million. Each laser line can be tuned by + or - 110 GHz with first-order sidebands.

  10. A Laser-Pointer-Based Spectrometer for Endpoint Detection of EDTA Titrations

    ERIC Educational Resources Information Center

    Dahm, Christopher E.; Hall, James W.; Mattioni, Brian E.

    2004-01-01

    A laser spectrometer for the ethylenediaminetetra-acetic acid (EDTA) titration of magnesium or calcium ions that is designed around a handheld laser pointer as the source and a photoresistor as the detector is developed. Findings show that the use of the spectrometer reduces the degree of uncertainty and error in one part of the EDTA titrations,…

  11. Future Development Trajectories for Imaging X-rays Spectrometers Based on Microcalorimeters

    NASA Technical Reports Server (NTRS)

    Kilbourne, Caroline A.; Bandler, Simon R.

    2013-01-01

    Future development trajectories for imaging x-ray spectrometers based on microcalorimeters. Since their invention 30 years ago, the capability of X-ray microcalorimeters has increased steadily, with continual improvements in energy resolution, speed, and array size. Arrays of up to 1024 pixels have been produced, and resolution better than 1 eV at 1.5 keV has been achieved. These detectors can be optimized for the highest priority science, such as designing for the highest resolving power at low energies at the expense of dynamic range, or the greatest focal-plane coverage at the expense of speed. Three types of X-ray microcalorimeters presently dominate the field, each characterized by the thermometer technology. The first two types use temperature-sensitive resistors: semiconductors in the metal-insulator transition and superconductors operated in the superconducting-normal transition. The third type uses a magnetically coupled thermometer, and is at an earlier stage of development than the other two. The Soft X-ray Spectrometer (SXS) on Astro-H, expected to launch in 2015, will use an array of silicon thermistors with HgTe X-ray absorbers that will operate at 50 mK. Both the semiconductor and superconductor calorimeters have been implemented in small arrays. Kilopixel arrays of the superconducting calorimeters are being produced, and much larger arrays may require the non-dissipative advantage of magnetically coupled thermometers. I will project the development trajectories of these detectors and their read-out technologies and assess what their capabilities and limitations will be 10 - 20 years from now.

  12. Developing a narrow-line laser spectrometer based on a tunable continuous-wave dye laser

    SciTech Connect

    Wang, Chun; Lv, Shasha; Bi, Jin; Liu, Fang; Li, Liufeng; Chen, Lisheng

    2014-08-15

    We present the development of a dye-laser-based spectrometer operating at 550–600 nm. The spectrometer will be used to detect an ultra-narrow clock transition ({sup 1}S{sub 0}-{sup 3}P{sub 0}) in an Ytterbium optical lattice clock and perform high-resolution spectroscopy of iodine molecules trapped in the sub-nanometer channels of zeolite crystal (AlPO{sub 4}-11). Two-stage Pound-Drever-Hall frequency stabilization is implemented on the tunable continuous-wave dye laser to obtain a reliable operation and provide stable laser radiations with two different spectral linewidths. In the first-stage frequency locking, a compact home-built intracavity electro-optic modulator is adopted for suppressing fast frequency noise. With an acquisition time of 0.1 s the 670-kHz linewidth of the free-running dye laser is reduced to 2 kHz when locked to a pre-stabilization optical cavity with a finesse of 1170. When the pre-stabilized laser is locked to a high-finesse optical cavity, a linewidth of 1.4 Hz (2 s) is observed and the frequency stability is 3.7 × 10{sup −15} (3 s). We also measure and analyze the individual noise contributions such as those from residual amplitude modulation and electronic noise. The ongoing upgrades include improving long-term frequency stability at time scales from 10 to 100 s and implementing continuous frequency scan across 10 GHz with radio-frequency precision.

  13. Absorption Filter Based Optical Diagnostics in High Speed Flows

    NASA Technical Reports Server (NTRS)

    Samimy, Mo; Elliott, Gregory; Arnette, Stephen

    1996-01-01

    Two major regimes where laser light scattered by molecules or particles in a flow contains significant information about the flow are Mie scattering and Rayleigh scattering. Mie scattering is used to obtain only velocity information, while Rayleigh scattering can be used to measure both the velocity and the thermodynamic properties of the flow. Now, recently introduced (1990, 1991) absorption filter based diagnostic techniques have started a new era in flow visualization, simultaneous velocity and thermodynamic measurements, and planar velocity measurements. Using a filtered planar velocimetry (FPV) technique, we have modified the optically thick iodine filter profile of Miles, et al., and used it in the pressure-broaden regime which accommodates measurements in a wide range of velocity applications. Measuring velocity and thermodynamic properties simultaneously, using absorption filtered based Rayleigh scattering, involves not only the measurement of the Doppler shift, but also the spectral profile of the Rayleigh scattering signal. Using multiple observation angles, simultaneous measurement of one component velocity and thermodynamic properties in a supersonic jet were measured. Presently, the technique is being extended for simultaneous measurements of all three components of velocity and thermodynamic properties.

  14. Tuneable dual-comb spectrometer based on commercial femtosecond lasers and reference cell for optical frequency calibration

    NASA Astrophysics Data System (ADS)

    Portuondo-Campa, E.; Bennès, J.; Balet, L.; Kundermann, S.; Merenda, F.; Boer, G.; Lecomte, S.

    2016-07-01

    Two commercial femtosecond laser sources have been used to implement a dual-comb spectrometer tuneable across a spectral range from 1.5 to 2.2 μm. The optical linewidth of the comb modes was characterized for different time scales in order to estimate the achievable spectral resolution for an optimal acquisition time. The transmission spectra of three different gas samples were recorded, demonstrating good agreement with reference data. Frequency axis calibration was provided via the parallel monitoring of a reference sample. This technique allows an accurate calibration of the frequency axis of the spectrometer, with no need for stabilization or optical referencing of the frequency combs. Our set-up represents a good compromise for a compact and versatile dual-comb spectrometer based on commercially available parts with possible applications in trace-gas monitoring, remote sensing and spectroscopy of short-lived processes.

  15. HAND-HELD GAMMA-RAY SPECTROMETER BASED ON HIGH-EFFICIENCY FRISCH-RING CdZnTe DETECTORS.

    SciTech Connect

    CUI,Y.

    2007-05-01

    Frisch-ring CdZnTe detectors have demonstrated good energy resolution, el% FWHM at 662 keV, and good efficiency for detecting gamma rays. This technique facilitates the application of CdZnTe materials for high efficiency gamma-ray detection. A hand-held gamma-ray spectrometer based on Frisch-ring detectors is being designed at Brookhaven National Laboratory. It employs an 8x8 CdZnTe detector array to achieve a high volume of 19.2 cm3, so that detection efficiency is significantly improved. By using the front-end ASICs developed at BNL, this spectrometer has a small profile and high energy resolution. The spectrometer includes signal processing circuit, digitization and storage circuit, high-voltage module, and USB interface. In this paper, we introduce the details of the system structure and report our test results with it.

  16. X-Band EPR Spectrometer with Customizable Arbitrary Waveform Generator based on a 1 GHz DAC Board

    NASA Astrophysics Data System (ADS)

    Kaufmann, Thomas

    We present an electron paramagnetic resonance (EPR) spectrometer featuring an arbitrary waveform generator (AWG) operating at 8-10 GHz (X-band) and based on a 1 GHz digital-to-analog converter (DAC) board with a 42 dB (i.e. 14-bit) dynamic range, which was developed to widen the scope of pulsed EPR and enable new experiments. This spectrometer generates shaped pulses with precise amplitude and phase control and can specify pulse lengths and delays with a time resolution of ≤250 ps. We demonstrate the capabilities of the spectrometer by presenting spin-echo measurements that implement an entirely digitally controlled and calibrated 16-step phase cycle and by measuring the excitation profiles seen by the spins in the microwave resonator as they respond to various pulse shapes, including rectangular, triangular, Gaussian, sinc and adiabatic rapid passage waveforms. Potential applications of these capabilities, and their implementation in commercial instrumentation will be discussed.

  17. An alpha–gamma coincidence spectrometer based on the Photon–Electron Rejecting Alpha Liquid Scintillation (PERALS®) system

    DOE PAGES

    Cadieux, J. R.; Fugate, G. A.; King, III, G. S.

    2015-02-07

    Here, an alpha–gamma coincidence spectrometer has been developed for the measurement of selected actinide isotopes in the presence of high beta/gamma fields. The system is based on a PERALS® liquid scintillation counter for beta/alpha discrimination and was successfully tested with both high purity germanium and bismuth germanate, gamma-ray detectors using conventional analog electronics.

  18. PC-based Data Acquisition System for X-ray Crystal Spectrometer

    NASA Astrophysics Data System (ADS)

    Nam, U. W.; Kong, K. N.; Park, Y. S.; Kim, Y. J.; Lee, S. G.; Bak, J. G.; Bitter, M.; Hill, K.; Moon, M. K.; Cheon, J. K.; Lee, C. H.

    2003-10-01

    A PC-based data acquisition system for an X-ray crystal spectrometer has been developed in order to measure the ion and electron temperature profile measurements on tokamak plasmas. The system can detect a 2D image of the plasma from a gas-filled delay line readout position-sensitive 2D detector and spherically-bent crystal in connection with N110 time to digital converter developed in European Synchrotron Radiation Facility. The N110 interface module with TMS320VC33 digital signal processor, and 16 Mbytes static memory and its supporting Windows OS image software are used for the PC-based data acquisition system. An USB (Universal Serial Bus) interface of the PC was used to get image data from the system with higher than 10 Mbytes/s throughput rate because of its simplicity and high-speed communication capability. The system has two acquisition modes - a static and dynamic modes - which can build 256 x 256, 512 x 512, 1024 x 1024 and 2048 x2048 image frames. The dynamic mode is designed to obtain and store the position and time information of each photon events simultaneously with the maximum count-rate capability up to 500 kHz. An overview and demonstration of the PC-based data acquisition system will be presented.

  19. NO2 column amounts from ground-based Pandora and MFDOAS spectrometers using the direct-sun DOAS technique: Intercomparisons and application to OMI validation

    NASA Astrophysics Data System (ADS)

    Herman, Jay; Cede, Alexander; Spinei, Elena; Mount, George; Tzortziou, Maria; Abuhassan, Nader

    2009-07-01

    Vertical column amounts of nitrogen dioxide, C(NO2), are derived from ground-based direct solar irradiance measurements using two new and independently developed spectrometer systems, Pandora (Goddard Space Flight Center) and MFDOAS (Washington State University). We discuss the advantages of C(NO2) retrievals based on Direct Sun - Differential Optical Absorption Spectroscopy (DS-DOAS). The C(NO2) data are presented from field campaigns using Pandora at Aristotle University (AUTH), Thessaloniki, Greece; a second field campaign involving both new instruments at Goddard Space Flight Center (GSFC), Greenbelt, Maryland; a Pandora time series from December 2006 to October 2008 at GSFC; and a MFDOAS time series for spring 2008 at Pacific Northwest National Laboratory (PNNL), Richland, Washington. Pandora and MFDOAS were compared at GFSC and found to closely agree, with both instruments having a clear-sky precision of 0.01 DU (1 DU = 2.67 × 1016 molecules/cm2) and a nominal accuracy of 0.1 DU. The high precision is obtained from careful laboratory characterization of the spectrometers (temperature sensitivity, slit function, pixel to pixel radiometric calibration, and wavelength calibration), and from sufficient measurement averaging to reduce instrument noise. The accuracy achieved depends on laboratory-measured absorption cross sections and on spectrometer laboratory and field calibration techniques used at each measurement site. The 0.01 DU precision is sufficient to track minute-by-minute changes in C(NO2) throughout each day with typical daytime values ranging from 0.2 to 2 DU. The MFDOAS instrument has better noise characteristics for a single measurement, which permits MFDOAS to operate at higher time resolution than Pandora for the same precision. Because Pandora and MFDOAS direct-sun measurements can be made in the presence of light to moderate clouds, but with reduced precision (˜0.2 DU for moderate cloud cover), a nearly continuous record can be obtained

  20. Study of the CH2I + O2 Reaction with a Step-Scan Fourier-Transform Infrared Absorption Spectrometer: Spectra of the Criegee Intermediate CH2OO and DIOXIRANE(?)

    NASA Astrophysics Data System (ADS)

    Huang, Yu-Hsuan; Lee, Yuan-Pern

    2014-06-01

    The Criegee intermediates are carbonyl oxides that play key roles in ozonolysis of unsaturated organic compounds. This mechanism was first proposed by Criegee in 1949, but the first direct observation of the simplest Criegee intermediate CH2OO in the gaseous phase has been reported only recently using photoionization mass spectrometry. Our group has reported the low-resolution IR spectra of CH2OO, produced from the reaction of CH2I + O2, with a second-generation step-scan Fourier-transfom IR absorption spectrometer. The spectral assignments were based on comparison of observed vibrational wavenumbers and rotational contours with theoretical predictions. Here, we report the IR absorption spectra of CH2OO at a resolution of 0.32 wn, showing partially rotationally-resolved structures. The origins of the νb{3}, νb{4}, νb{6}, and νb{8} vibrational modes of CH2OO are determined to be 1434.1, 1285.7, 909.2, and 847.3 wn, respectively. With the analysis of the vibration-rotational spectra, we provide a definitive assignment of these bands to CH2OO. The observed vibrational wavenumbers indicate a zwitterionic contribution to this singlet biradical showing a strengthened C-O bond and a weakened O-O bond. This zwitterionic character results to an extremely rapid self reaction via a cyclic dimer to form 2H2CO + O2 (1Δg). Another group of weak transient IR bands centered at 1231.5, 1213.3, and 899.8 wn are also observed. These bands might be contributed from dioxirane, which was postulated to be another important intermediate that might be isomerized from the Criegee intermediate in the reaction of O3 with 1-alkenes. O. Welz, J. D. Savee, D. L. Osborn, S. S.Vasu, C. J. Percival, D. E. Shallcross, and C. A. Taatjes, Science 335, 204 (2012). Y.-T. Su, Y.-H. Huang, H. A.Witek, and Y.-P. Lee, Science 340, 174 (2013).

  1. Test of a prototype neutron spectrometer based on diamond detectors in a fast reactor

    SciTech Connect

    Osipenko, M.; Ripani, M.; Ricco, G.; Caiffi, B.; Pompili, F.; Pillon, M.; Angelone, M.; Verona-Rinati, G.; Cardarelli, R.; Argiro, S.

    2015-07-01

    A prototype of neutron spectrometer based on diamond detectors has been developed. This prototype consists of a {sup 6}Li neutron converter sandwiched between two CVD diamond crystals. The radiation hardness of the diamond crystals makes it suitable for applications in low power research reactors, while a low sensitivity to gamma rays and low leakage current of the detector permit to reach good energy resolution. A fast coincidence between two crystals is used to reject background. The detector was read out using two different electronic chains connected to it by a few meters of cable. The first chain was based on conventional charge-sensitive amplifiers, the other used a custom fast charge amplifier developed for this purpose. The prototype has been tested at various neutron sources and showed its practicability. In particular, the detector was calibrated in a TRIGA thermal reactor (LENA laboratory, University of Pavia) with neutron fluxes of 10{sup 8} n/cm{sup 2}s and at the 3 MeV D-D monochromatic neutron source named FNG (ENEA, Rome) with neutron fluxes of 10{sup 6} n/cm{sup 2}s. The neutron spectrum measurement was performed at the TAPIRO fast research reactor (ENEA, Casaccia) with fluxes of 10{sup 9} n/cm{sup 2}s. The obtained spectra were compared to Monte Carlo simulations, modeling detector response with MCNP and Geant4. (authors)

  2. A Fourier Transform Spectrometer Based on an Electrothermal MEMS Mirror with Improved Linear Scan Range

    PubMed Central

    Wang, Wei; Chen, Jiapin; Zivkovic, Aleksandar. S.; Xie, Huikai

    2016-01-01

    A Fourier transform spectrometer (FTS) that incorporates a closed-loop controlled, electrothermally actuated microelectromechanical systems (MEMS) micromirror is proposed and experimentally verified. The scan range and the tilting angle of the mirror plate are the two critical parameters for MEMS-based FTS. In this work, the MEMS mirror with a footprint of 4.3 mm × 3.1 mm is based on a modified lateral-shift-free (LSF) bimorph actuator design with large piston and reduced tilting. Combined with a position-sensitive device (PSD) for tilt angle sensing, the feedback controlled MEMS mirror generates a 430 µm stable linear piston scan with the mirror plate tilting angle less than ±0.002°. The usable piston scan range is increased to 78% of the MEMS mirror’s full scan capability, and a spectral resolution of 0.55 nm at 531.9 nm wavelength, has been achieved. It is a significant improvement compared to the prior work. PMID:27690047

  3. Evanescent wave absorption sensor based on tapered multimode fiber coated with monolayer graphene film

    NASA Astrophysics Data System (ADS)

    Qiu, Hengwei; Gao, Saisai; Chen, Peixi; Li, Zhen; Liu, Xiaoyun; Zhang, Chao; Xu, Yuanyuan; Jiang, Shouzhen; Yang, Cheng; Huo, Yanyan; Yue, Weiwei

    2016-05-01

    An evanescent wave absorption (EWA) sensor based on tapered multimode fiber (TMMF) coated with monolayer graphene film for the detection of double-stranded DNA (DS-DNA) is investigated in this work. The TMMF is a silica multimode fiber (nominally at 62.5 μm), which was tapered to symmetric taper with waist diameters of ~30 μm and total length of ~3 mm. Monolayer graphene film was grown on a copper foil via chemical vapor deposition (CVD) technology and transferred onto skinless tapered fiber core via dry transfer technology. All the components of the sensor are coupled together by fusion splicer in order to eliminate the external disturbance. DS-DNA is created by the assembly of two relatively complemented oligonucleotides. The measurements are obtained by using a spectrometer in the optical wavelength range of 400-900 nm. With the increase of DS-DNA concentration, the output light intensity (OPLI) arisen an obvious attenuation. Importantly, the absorbance (A) and the DS-DNA concentrations shown a reasonable linear variation in a wide range of 5-400 μM. Through a series of comparison, the accuracy of TMMF sensor with graphene (G-TMMF) is much better than that without graphene (TMMF), which can be attributed to the molecular enrichment of graphene by π-π stacking.

  4. All-optical reservoir computer based on saturation of absorption.

    PubMed

    Dejonckheere, Antoine; Duport, François; Smerieri, Anteo; Fang, Li; Oudar, Jean-Louis; Haelterman, Marc; Massar, Serge

    2014-05-05

    Reservoir computing is a new bio-inspired computation paradigm. It exploits a dynamical system driven by a time-dependent input to carry out computation. For efficient information processing, only a few parameters of the reservoir needs to be tuned, which makes it a promising framework for hardware implementation. Recently, electronic, opto-electronic and all-optical experimental reservoir computers were reported. In those implementations, the nonlinear response of the reservoir is provided by active devices such as optoelectronic modulators or optical amplifiers. By contrast, we propose here the first reservoir computer based on a fully passive nonlinearity, namely the saturable absorption of a semiconductor mirror. Our experimental setup constitutes an important step towards the development of ultrafast low-consumption analog computers.

  5. Novel carbon dioxide gas sensor based on infrared absorption

    NASA Astrophysics Data System (ADS)

    Zhang, Guangjun; Lui, Junfang; Yuan, Mei

    2000-08-01

    The feasibility of sensing carbon dioxide with a IR single- beam optical structure is studied, and a novel carbon dioxide gas sensor based on IR absorption is achieved. Applying the Lambert-Beer law and some key techniques such as current stabilization for IR source, using a high-quality IR detector, and data compensation for the influences of ambience temperature and atmosphere total pressure, the sensor can measure carbon dioxide with high precision and efficiency. The mathematical models for providing temperature and pressure compensation for the sensor are established. Moreover the solutions to the models are proposed. Both the models and the solutions to the models are verified via experiments. The sensor possesses the advantages of small volume, light weight, low power consumption, and high reliability. Therefore it can be used in many associated fields, such as environmental protection, processing control, chemical analysis, medical diagnosis, and space environmental and control systems.

  6. 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.

  7. [VMTBB-Based Spectral Radiometric Calibration of NIR Fiber Coupled Spectrometer].

    PubMed

    Zheng, Feng; Liu, Li-ying; Liu, Xiao-xi; Li, Ye; Shi, Xiao-guang; Zhang, Guo-yu; Huan, Ke-wei

    2015-09-01

    The medium temperature black body (MTBB) is conventional high precision equipment used as spectral radiometric scale in infrared spectral region. However, in near-infrared (NIR) spectral region, there are few papers about spectral radiometric calibration by using MTBB, that is because NIR spectral region is the borderland of its effective spectral region. The main research of this paper is spectral radiometric calibration method by using MTBB in NIR spectral region. Accordingly, this paper is devoted mostly to a discussion of how the calibration precision could be affected by selecting different structural parameters of calibration model. The purpose of this paper is to present the results of research and provide technical reference for improving the traceability in NIR spectral radiometric calibration. In this paper, a NIR fiber coupled spectrometer, whose wavelength range covers from 950 to 1700 nm, has been calibrated by a MTBB with adjustable temperature range from 50 to 1050 °C. Concentrating on calibration process, two key points have been discussed. For one thing, the geometric factors of radiation transfer model of the calibration systems have been compared between traditional structure and fiber direct-coupled structure. Because the fiber direct-coupled model is simple and effective, it has been selected instead of traditional model based on the radiation transfer between two coaxial discs. So, it is an advantaged radiation transfer model for radiometric calibration of fiber coupled spectrometer. For another thing, the relation between calibration accuracy and structural parameters of calibration model has been analyzed intensively. The root cause is scale feature of attribute of calibration data itself, which is the nonlinear structure in scales of spectral data. So, the high precision calibration needs nonlinear calibration model, and the uniform sampling for scale feature is also very important. Selecting sample is an inevitable problem when the

  8. HAB detection based on absorption and backscattering properties of phytoplankton

    NASA Astrophysics Data System (ADS)

    Lei, Hui; Pan, Delu; Bai, Yan; Chen, Xiaoyan; Zhou, Yan; Zhu, Qiankun

    2011-11-01

    The coastal area of East China Sea (ECS) suffers from the harmful algal blooms (HAB) frequently every year in the warm season. The most common causative phytoplankton algal species of HAB in the ECS in recent years are Prorocentrum donghaiense (dinoflagellates), Karenia mikimotoi (dinoflagellates which could produce hemolytic and ichthyotoxins) and Skeletonema costatum (diatom). The discrimination between the dinoflagellates and diatom HAB through ocean color remote sensing approach can add the knowledge of HAB events in ECS and help to the precaution. A series of in-situ measurement consisted of absorption coefficient, total scattering and particulate backscattering coefficient was conducted in the southern coast of Zhejiang Province in May 2009, and the estuary of Changjiang River in August 2009 and December 2010, which encountered two HAB events and a moderate bloom. The Inherent Optical Properties (IOPs) of the bloom waters have significant difference between phytoplankton species in absorption and backscattering properties. The chlorophyll a specific absorption coefficient (a*phy(λ)) for the bloom patches (chlorophyll a concentration >6mg m-3) differ greatly from the adjacent normal seawater, with the a*phy(λ) of bloom water lower than 0.03 m2 mg-1 while the a*phy(λ) of the adjacent normal seawater is much higher (even up to 0.06 m2 mg-1). Meanwhile, the backscattering coefficients at 6 wavebands (420, 442, 470, 510, 590 and 700nm) are also remarkably lower for bloom waters (<0.01 m-1) than the normal seawater (> 0.02 m-1). The backscattering coefficient ratio (Rbp(λ)) is much lower for diatom bloom waters than for dinoflagellates types (0.01079 vs. 0.01227). A discrimination model based on IOPs is established, and several typical dinoflagellates and diatom bloom events including Prorocentrum donghaiense, Karenia mikimotoi and Skeletonema costatum in the ECS are picked out for testing with the MODIS-L2 and L3 ocean color remote sensing products from NASA

  9. Development of a compact laser-based single photon ionization time-of-flight mass spectrometer

    NASA Astrophysics Data System (ADS)

    Tonokura, Kenichi; Kanno, Nozomu; Yamamoto, Yukio; Yamada, Hiroyuki

    2010-02-01

    We have developed a compact, laser-based, single photon ionization time-of-flight mass spectrometer (SPI-TOF-MS) for on-line monitoring of trace organic species. To obtain the mass spectrum, we use a nearly fragmentation-free SPI technique with 10.5 eV (118 nm) vacuum ultraviolet laser pulses generated by frequency tripling of the third harmonic of an Nd:YAG laser. The instrument can be operated in a linear TOF-MS mode or a reflectron TOF-MS mode in the coaxial design. We designed ion optics to optimize detection sensitivity and mass resolution. For data acquisition, the instrument is controlled using LabVIEW control software. The total power requirement for the vacuum unit, control electronics unit, ion optics, and detection system is approximately 100 W. We achieve a detection limit of parts per billion by volume (ppbv) for on-line trace analysis of several organic compounds. A mass resolution of 800 at about 100 amu is obtained for reflectron TOF-MS mode in a 0.35 m long instrument. The application of on-line monitoring of diesel engine exhaust was demonstrated.

  10. Design, integration, and testing of a compact FBG interrogator, based on an AWG spectrometer

    NASA Astrophysics Data System (ADS)

    Trita, Andrea; Vickers, Garrie; Mayordomo, Iker; van Thourhout, Dries; Vermeiren, Jan

    2014-05-01

    Fiber Bragg Grating or FBG sensors are gaining more and more interest in structural health monitoring of composite materials. Often, the weakest point in such a system is the ingress point of the fiber sensing chain into the composite material. For this reason we have developed a strongly miniaturized FBG interrogator unit with wireless power and data transmission, which can be incorporated in the composite structure. The interrogator is based on an arrayed waveguide grating (AWG) filter fabricated in a SOI technology, which is tailored in such a way to give large cross-talk between neighboring channels. The AWG signals are read by a linear 128 pixel InGaAs array flip-chipped on top of the Photonic Circuit (PIC). The spectrometer unit is completed with a ROIC mounted on the same substrate. The SLED and remaining electronics are integrated on a small and thin substrate and surrounded by the wireless antenna. The interrogator has an overall dimension of 100 mm diameter by max 7 mm height. The power dissipation of the electronics unit is limited to 1.5 W. The unit is capable of measuring strain values as low as 5 micro-strain.

  11. Light collection optimization in scintillator-based gamma-ray spectrometers

    NASA Astrophysics Data System (ADS)

    Hull, G.; Du, S.; Niedermayr, T.; Payne, S.; Cherepy, N.; Drobshoff, A.; Fabris, L.

    2008-04-01

    Scintillator-based gamma-ray detectors are being actively pursued for homeland security applications. A key property of such detectors is their energy resolution which enables faster detection and more precise identification of gamma-ray sources. In order to obtain the best energy resolution with a given scintillator material, it is crucial to collect the largest fraction possible of the light emitted after gamma-ray absorption. Different techniques to maximize the light collection efficiency were investigated and tested experimentally. In particular, the effect of the scintillator geometry has been simulated with Detect2000. Also, a number of wrapping materials have been tested for their reflectivity and their performance in terms of improving the energy resolution in a BGO-based gamma-ray detector. The best results were obtained with a tapered cylinder geometry and the GORE DRP tape.

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  13. Development and Characterization of a High Speed Mid-IR Tunable Diode Laser Absorption Spectrometer for CO and CO2 Detection in Detonation Events

    DTIC Science & Technology

    2014-03-27

    expected results with approximately 10% error bounds. With this system’s proof of concept, it will be possible to analyze real combustors as well as...the intensity is normalized ac - cording to an intensity where no absorption occurs according to Beer’s Law. Furthermore, the plots now focus on the...Data for CO (top) and CO2 (bottom) in which the intensity is normalized ac - cording to an intensity where no absorption occurs according to Beer’s

  14. Design, fabrication and deployment of a miniaturized spectrometer radiometer based on MMIC technology for tropospheric water vapor profiling

    NASA Astrophysics Data System (ADS)

    Iturbide-Sanchez, Flavio

    This dissertation describes the design, fabrication and deployment of the Compact Microwave Radiometer for Humidity profiling (CMR-H). The CMR-H is a new and innovative spectrometer radiometer that is based on monolithic microwave and millimeter-wave integrated circuit (MMIC) technology and is designed for tropospheric water vapor profiling. The CMR-H simultaneously measures microwave emission at four optimally-selected frequency channels near the 22.235 GHz water vapor absorption line, constituting a new set of frequencies for the retrieval of the water vapor profile. State-of-the-art water vapor radiometers either measure at additional channels with redundant information or perform multi-frequency measurements sequentially. The fabrication of the CMR-H demonstrates the capability of MMIC technology to reduce substantially the operational power consumption and size of the RF and IF sections. Those sections comprise much of the mass and volume of current microwave receivers for remote sensing, except in the case of large antennas. The use of the compact box-horn array antenna in the CMR-H demonstrates its capability to reduce the mass and volume of microwave radiometers, while maintaining similar performance to that of commonly-used, bulky horn antennas. Due to its low mass, low volume, low power consumption, fabrication complexity and cost, the CMR-H represents a technological improvement in the design of microwave radiometers for atmospheric water vapor observations. The field test and validation of the CMR-H described in this work focuses on comparisons of measurements during two field experiments from the CMR-H and a state-of-the-art microwave radiometer, which measures only in a volume subtended by the zenith-pointing antenna's beam pattern. In contrast, the CMR-H is designed to perform volumetric scans and to function correctly as a node in a network of radiometers. Mass production of radiometers based on the CMR-H design is expected to enable the

  15. Models of ionospheric VLF absorption of powerful ground based transmitters

    NASA Astrophysics Data System (ADS)

    Cohen, M. B.; Lehtinen, N. G.; Inan, U. S.

    2012-12-01

    Ground based Very Low Frequency (VLF, 3-30 kHz) radio transmitters play a role in precipitation of energetic Van Allen electrons. Initial analyses of the contribution of VLF transmitters to radiation belt losses were based on early models of trans-ionospheric propagation known as the Helliwell absorption curves, but some recent studies have found that the model overestimates (by 20-100 dB) the VLF energy reaching the magnetosphere. It was subsequently suggested that conversion of wave energy into electrostatic modes may be responsible for the error. We utilize a newly available extensive record of VLF transmitter energy reaching the magnetosphere, taken from the DEMETER satellite, and perform a direct comparison with a sophisticated full wave model of trans-ionospheric propagation. Although the model does not include the effect of ionospheric irregularities, it correctly predicts the average total power injected into the magnetosphere within several dB. The results, particularly at nighttime, appear to be robust against the variability of the ionospheric electron density. We conclude that the global effect of irregularity scattering on whistler mode conversion to quasi-electrostatic may be no larger than 6 dB.

  16. A novel CO 2 gas analyzer based on IR absorption

    NASA Astrophysics Data System (ADS)

    Zhang, Guangjun; Wu, Xiaoli

    2004-08-01

    Carbon dioxide (CO 2) gas analyzer can be widely used in many fields. A novel CO 2 gas analyzer based on infrared ray (IR) absorption is presented sufficiently in this paper. Applying Lambert-Beer Law, a novel space-double-beam optical structure is established successfully. The optical structure includes an IR source, a gas cell, a bandpass filter with a transmission wavelength at 4.26 μm, another bandpass filter with a transmission wavelength at 3.9 μm, and two IR detectors. Based on Redial Basic Function (RBF) artificial neural network, the measuring model of IR CO 2 analyzer is established with a high accuracy. A dynamic compensation filter is effectively designed to improve the dynamic characteristic of the IR CO 2 analyzer without gas pump. The IR CO 2 analyzer possesses the advantages of high accuracy and mechanical reliability with small volume, lightweight, and low-power consumption. Therefore, it can be used in such relevant fields as environmental protection, processing control, chemical analysis, medical diagnosis, and space environmental and control systems.

  17. THz QCL-Based Cryogen-Free Spectrometer for in Situ Trace Gas Sensing

    PubMed Central

    Consolino, Luigi; Bartalini, Saverio; Beere, Harvey E.; Ritchie, David A.; Vitiello, Miriam Serena; De Natale, Paolo

    2013-01-01

    We report on a set of high-sensitivity terahertz spectroscopy experiments making use of QCLs to detect rotational molecular transitions in the far-infrared. We demonstrate that using a compact and transportable cryogen-free setup, based on a quantum cascade laser in a closed-cycle Stirling cryostat, and pyroelectric detectors, a considerable improvement in sensitivity can be obtained by implementing a wavelength modulation spectroscopy technique. Indeed, we show that the sensitivity of methanol vapour detection can be improved by a factor ≈ 4 with respect to standard direct absorption approaches, offering perspectives for high sensitivity detection of a number of chemical compounds across the far-infrared spectral range. PMID:23478601

  18. 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.

  19. SCINTILLATION SPECTROMETER

    DOEpatents

    Bell, P.R.; Francis, J.E.

    1960-06-21

    A portable scintillation spectrometer is described which is especially useful in radio-biological studies for determining the uptake and distribution of gamma -emitting substances in tissue. The spectrometer includes a collimator having a plurality of apertures that are hexagonal in cross section. Two crystals are provided: one is activated to respond to incident rays from the collimator; the other is not activated and shields the first from external radiation.

  20. A broadband Fourier transform microwave spectrometer based on chirped pulse excitation.

    PubMed

    Brown, Gordon G; Dian, Brian C; Douglass, Kevin O; Geyer, Scott M; Shipman, Steven T; Pate, Brooks H

    2008-05-01

    Designs for a broadband chirped pulse Fourier transform microwave (CP-FTMW) spectrometer are presented. The spectrometer is capable of measuring the 7-18 GHz region of a rotational spectrum in a single data acquisition. One design uses a 4.2 Gsampless arbitrary waveform generator (AWG) to produce a 1 mus duration chirped pulse with a linear frequency sweep of 1.375 GHz. This pulse is sent through a microwave circuit to multiply the bandwidth of the pulse by a factor of 8 and upconvert it to the 7.5-18.5 GHz range. The chirped pulse is amplified by a traveling wave tube amplifier and broadcast inside the spectrometer by using a double ridge standard gain horn antenna. The broadband molecular free induction decay (FID) is received by a second horn antenna, downconverted, and digitized by a 40 Gsampless (12 GHz hardware bandwidth) digital oscilloscope. The second design uses a simplified pulse generation and FID detection scheme, employing current state-of-the-art high-speed digital electronics. In this spectrometer, a chirped pulse with 12 GHz of bandwidth is directly generated by using a 20 Gsampless AWG and upconverted in a single step with an ultrabroadband mixer. The amplified molecular emission is directly detected by using a 50 Gsampless digital oscilloscope with 18 GHz bandwidth. In both designs, fast Fourier transform of the FID produces the frequency domain rotational spectrum in the 7-18 GHz range. The performance of the CP-FTMW spectrometer is compared to a Balle-Flygare-type cavity-FTMW spectrometer. The CP-FTMW spectrometer produces an equal sensitivity spectrum with a factor of 40 reduction in measurement time and a reduction in sample consumption by a factor of 20. The CP-FTMW spectrometer also displays good intensity accuracy for both sample number density and rotational transition moment. Strategies to reduce the CP-FTMW measurement time by another factor of 90 while simultaneously reducing the sample consumption by a factor of 30 are demonstrated.

  1. TANGOO: A ground-based tilting-filter spectrometer for deriving the temperature in the mesopause region

    NASA Astrophysics Data System (ADS)

    Wildner, S.; Bittner, M.

    2009-04-01

    TANGOO (Tilting-filter spectrometer for Atmospheric Nocturnal Ground-based Oxygen & hydrOxyl emission measurements) is a passive, ground-based optical instrument for the purpose of a simultanously automatic long-term monitoring of OH(6-2) and O2 atm. Band (0-1) emissions (called "airglow"), yielding rotational temperatures in about 87 and 95 km, respectively. TANGOO, being a transportable and comparatively easy-to-use instrument, is the enhancement of the Argentine Airglow Spectrometer (Scheer, 1987) and shows significant improvements in the temporal resolution and throughput. It will be located on the German Enviromental Research Station "Schneefernerhaus", Zugspitze (47°,4 N, 11° E) and will start measurements in 2009. Objectives of TANGOO cover the analysis of dynamical processes such as gravity waves as well as the identification of climate signals. The observation method will be presented.

  2. A novel method of creating a surface micromachined 3D optical assembly for MEMS-based miniaturized FTIR spectrometers

    NASA Astrophysics Data System (ADS)

    Reyes, D.; Schildkraut, E. R.; Kim, J.; Connors, R. F.; Kotidis, P.; Cavicchio, D. J.

    2008-02-01

    This paper describes design, fabrication, and characterization of a miniaturized, Fourier transform infrared (FTIR) spectrometer for the detection and identification of toxic or flammable gases. By measuring the absorption by the target material of IR radiation, unambiguous detection and identification can be achieved. The key component of the device is a micromachined Michelson interferometer capable of modulating light in the 2 - 14 μm spectral region. Two major technical achievements associated with developing a MEMS interferometer module are discussed: development of a micromirror assembly having an order of magnitude larger modulation stroke to approach laboratory instrument-grade spectral resolutions; and assembly of monolithic, millimeter-scale optical components using multi-layer surface micromachining techniques to produce an extremely low cost MEMS interferometer, which has an unprecedented optical throughput. We have manufactured and tested the device. Reported optical characterization results include a precisely aligned, static interferogram acquired from an assembled Michelson interferometer using visible light wavelengths, which promises a high sensitivity FTIR spectrometer for its size.

  3. Water isotope ratio (δ2H and δ18O) measurements in atmospheric moisture using an optical feedback cavity enhanced absorption laser spectrometer

    NASA Astrophysics Data System (ADS)

    Iannone, Rosario Q.; Romanini, Daniele; Cattani, Olivier; Meijer, Harro A. J.; Kerstel, Erik R. Th.

    2010-05-01

    Water vapor isotopes represent an innovative and excellent tool for understanding complex mechanisms in the atmospheric water cycle over different time scales, and they can be used for a variety of applications in the fields of paleoclimatology, hydrology, oceanography, and ecology. We use an ultrasensitive near-infrared spectrometer, originally designed for use on airborne platforms in the upper troposphere and lower stratosphere, to measure the water deuterium and oxygen-18 isotope ratios in situ, in ground-level tropospheric moisture, with a high temporal resolution (from 300 s down to less than 1 s). We present some examples of continuous monitoring of near-surface atmospheric moisture, demonstrating that our infrared laser spectrometer could be used successfully to record high-concentration atmospheric water vapor mixing ratios in continuous time series, with a data coverage of ˜90%, interrupted only for daily calibration to two isotope ratio mass spectrometry-calibrated local water standards. The atmospheric data show that the water vapor isotopic composition exhibits a high variability that can be related to weather conditions, especially to changes in relative humidity. Besides, the results suggest that observed spatial and temporal variations of the stable isotope content of atmospheric water vapor are strongly related to water vapor transport in the atmosphere.

  4. UV absorption and scattering properties of inorganic-based sunscreens.

    PubMed

    Egerton, Terry A; Tooley, Ian R

    2012-04-01

    This article first introduces the concepts that underlie the calculations of scattering and absorption of light by small particles. Results of Mie theory calculations of light scattering and light absorption by 20, 50 and 100 nm TiO₂ and ZnO particles are then presented. As the attenuation, or extinction, by these particles is the sum of the scattering and absorption, the attenuation can then be calculated for wavelengths over the UVA and UVB region. These theoretical results are then shown to be in reasonable agreement with experimental results for alkyl benzoate dispersions of three different types of TiO₂ particle whose mean sizes range from 35 to 145 nm. Finally, the link between these measurements and the absorption curves of formulated dispersions of sunscreens are demonstrated and related to in vitro SPF and UVAPF measurements.

  5. Ammonia concentration distribution measurements in the exhaust of a heavy duty diesel engine based on limited data absorption tomography.

    PubMed

    Stritzke, Felix; van der Kley, Sani; Feiling, Alexander; Dreizler, Andreas; Wagner, Steven

    2017-04-03

    A multichannel tunable diode laser absorption spectrometer is used to measure absolute ammonia concentrations and their distributions in exhaust gas applications with intense CO2 and H2O background. Designed for in situ diagnostics in SCR after treatment systems with temperatures up to 800 K, the system employs a fiber coupled near-infrared distributed feedback diode laser. With the laser split into eight coplanar beams crossing the exhaust pipe, the sensor provides eight concentration measurements simultaneously. Three ammonia ro-vibrational transitions coinciding near 2200.5 nm with rather weak temperature dependency and negligible CO2/H2O interference were probed during the measurements. The line-of-sight averaged channel concentrations are transformed into 2-D ammonia distributions using limited data IR species tomography based on Tikhonov regularization. This spectrometer was successfully applied in the exhaust system of a 340 kW heavy duty diesel engine operated without oxidation catalyst or particulate filter. In this harsh environment the multi-channel sensor achieved single path ammonia detection limits of 25 to 80 ppmV with a temporal resolution of 1 Hz whereas, while operated as a single-channel sensor, these characteristics improved to 10 ppmV and 100 Hz. Spatial averaging of the reconstructed 2-D ammonia distributions shows good agreement to cross-sectional extractive measurements. In contrast to extractive methods more information about spatial inhomogeneities and transient operating conditions can be derived from the new spectrometer.

  6. Hand-Held Gamma-Ray Spectrometer Based on High-Efficiency Frisch-Ring Cdznte Detectors

    SciTech Connect

    Cui, Y.; Bolotnikov, A; Camarda, G; Hossain, A; James, R; DeGeronimo, G; Fried, J; O'Connor, P; Kargar, A; et. al.

    2008-01-01

    Frisch-ring CdZnTe detectors have demonstrated both good energy resolution, <1% FWHM at 662 keV, and good efficiency in detecting gamma rays, highlighting the strong potential of CdZnTe materials for such applications. We are designing a hand-held gamma-ray spectrometer based on Frisch-ring detectors at Brookhaven National Laboratory. It employs an 8 times 8 CdZnTe detector array to achieve a high volume of 19.2 cm3, so greatly improving detection efficiency. By using the front-end application-specific integrated circuits (ASICs) developed at BNL, this spectrometer has a small profile and high energy-resolution. It includes a signal processing circuit, digitization and storage circuits, a high-voltage module, and a universal serial bus (USB) interface. In this paper, we detail the system's structure and report the results of our tests with it.

  7. Urine surface-enhanced Raman spectroscopy for non-invasive diabetic detection based on a portable Raman spectrometer

    NASA Astrophysics Data System (ADS)

    Zou, Ye; Huang, Meizhen; Wang, Kehui; Song, Biao; Wang, Yang; Chen, Jie; Liu, Xi; Li, Xia; Lin, Lulu; Huang, Gaozhong

    2016-06-01

    A feasibility study for non-invasive diabetic detection based on a low cost portable Raman spectrometer and urine surface-enhanced Raman spectroscopy (SERS) is presented. SERS of 41 urine samples (20 diabetic patients and 21 healthy volunteers) mixed with silver nanoparticles are measured by a self-developed portable Raman spectrometer (Hx-Spec) which is excited by a 785 nm diode laser and the spectrum range is 200-2700 cm-1 with a resolution (FWHM) of 6 cm-1. By methods of principal components analysis and linear discriminant analysis, a diagnostic sensitivity of 85% and a specificity of 90.5% are achieved in separating diabetic samples from normal urine specimens. The corresponding receiver operating characteristic is 0.836, indicting the accuracy of the predictive model.

  8. New acoustical technology of sound absorption based on reverse horn

    NASA Astrophysics Data System (ADS)

    Zhang, Yong Yan; Wu, Jiu Hui; Cao, Song Hua; Cao, Pei; Zhao, Zi Ting

    2016-12-01

    In this paper, a novel reverse horn’s sound-absorption mechanism and acoustic energy focusing mechanism for low-frequency broadband are presented. Due to the alternation of the reverse horn’s thickness, the amplitude of the acoustic pressure propagated in the structure changes, which results in growing energy focused in the edge and in the reverse horn’s tip when the characteristic length is equal to or less than a wavelength and the incident wave is compressed. There are two kinds of methods adopted to realize energy dissipation. On the one hand, sound-absorbing materials are added in incident direction in order to overcome the badness of the reverse horn’s absorption in high frequency and improve the overall high-frequency and low-frequency sound-absorption coefficients; on the other hand, adding mass and film in its tip could result in mechanical energy converting into heat energy due to the coupled vibration of mass and the film. Thus, the reverse horn with film in the tip could realize better sound absorption for low-frequency broadband. These excellent properties could have potential applications in the one-dimensional absorption wedge and for the control of acoustic wave.

  9. Wideband absorption in fibonacci quasi-periodic graphene-based hyperbolic metamaterials

    NASA Astrophysics Data System (ADS)

    Ning, Renxia; Liu, Shaobin; Zhang, Haifeng; Kong, Xiangkun; Bian, Borui; Bao, Jie

    2014-12-01

    A heterostructure containing a Fibonacci quasi-periodic layer and a resonant metal back reflector is proposed, which can realize wideband absorption. The Fibonacci layer is composed of graphene-based hyperbolic metamaterials and isotropic media to obtain wideband absorption. To enhance absorption, an impedance-matching layer is put on top of the Fibonacci layer. It is shown to absorb roughly 90% of all available electromagnetic waves in an 11 terahertz absorption bandwidth for a transverse magnetic mode at normal angle incidence. The absorption bandwidth is affected by the reflection band gap. Compared with some previous designs, our proposed structure has a larger absorption bandwidth and higher absorption in the mid-infrared range. The results should be valuable in the design of infrared stealth and broadband optoelectronic devices.

  10. Hard X-ray polarimetry with Caliste, a high performance CdTe based imaging spectrometer

    NASA Astrophysics Data System (ADS)

    Antier, S.; Ferrando, P.; Limousin, O.; Caroli, E.; Curado da Silva, R. M.; Blondel, C.; Chipaux, R.; Honkimaki, V.; Horeau, B.; Laurent, P.; Maia, J. M.; Meuris, A.; Del Sordo, S.; Stephen, J. B.

    2015-06-01

    Since the initial exploration of the X- and soft γ-ray sky in the 60's, high-energy celestial sources have been mainly characterized through imaging, spectroscopy and timing analysis. Despite tremendous progress in the field, the radiation mechanisms at work in sources such as neutrons stars, black holes, and Active Galactic Nuclei are still unclear. The polarization state of the radiation is an observational parameter which brings key additional information about the physical processes in these high energy sources, allowing the discrimination between competing models which may otherwise all be consistent with other types of measurement. This is why most of the projects for the next generation of space missions covering the few tens of keV to the MeV region require a polarization measurement capability. A key element enabling this capability, in this energy range, is a detector system allowing the identification and characterization of Compton interactions as they are the main process at play. The compact hard X-ray imaging spectrometer module, developed in CEA with the generic name of "Caliste" module, is such a detector. In this paper, we present experimental results for two types of Caliste-256 modules, one based on a CdTe crystal, the other one on a CdZnTe crystal, which have been exposed to linearly polarized beams at the European Synchrotron Radiation Facility (ESRF). These results, obtained at 200 and 300 keV, demonstrate the capability of these modules to detect Compton events and to give an accurate determination of the polarization parameters (polarization angle and fraction) of the incoming beam. For example, applying an optimized selection to our data set, equivalent to select 90° Compton scattered interactions in the detector plane, we find a modulation factor Q of 0.78 ± 0.06 in the 200-300 keV range. The polarization angle and fraction are derived with accuracies of approximately 1° and 5 % respectively for both CdZnTe and CdTe crystals. The

  11. Development of a ten inch manipulators-based, flexible, broadband two-crystal spectrometer

    SciTech Connect

    Steel, A. B. Dunn, J.; Emig, J.; Beiersdorfer, P.; Brown, G. V.; Shepherd, R.; Marley, E. V.; Hoarty, D. J.

    2014-11-15

    We have developed and implemented a broadband X-ray spectrometer with a variable energy range for use at the Atomic Weapons Establishment's Orion Laser. The spectrometer covers an energy bandwidth of ∼1–2 keV using two independently mounted, movable Bragg diffraction crystals. Using combinations of cesium hydrogen pthlate, ammonium dihydrogen phosphate, and pentaerythritol crystals, spectra covering the 1.4–2.5, 1.85–3.15, or 3.55–5.1 keV energy bands have been measured. Image plate is used for detection owing to its high dynamic range. Background signals caused by high energy X-rays and particles commonly produced in high energy laser experiments are reduced by a series of tantalum baffles and filters installed between the source and crystal and also between the crystals and detector.

  12. A feasibility study of a single event spectrometer based on semiconductor devices.

    PubMed

    Agosteo, S; Castoldi, A; Castellani, L; Colautti, P; D'Angelo, G; De Nardo, L; Favalli, A; Lippi, I; Martinelli, R; Tornielli, G; Zotto, P

    2002-01-01

    The electronics employed around particle accelerators can be disturbed or damaged because of single event effects (SEE). The most likely effect is the single event upset (SEU) which may affect all memory devices. In the case of high energy accelerators, SEUs are mostly produced by secondary charged particles generated by neutron interactions. The measurement of the energy and the lineal energy distribution of these neutron-induced charged particles was proposed. As a first approach, a commercial p-i-n photodiode was employed. This device was irradiated with thermal and monoenergetic fast neutrons. Some effects limiting the use of such a detector as a SEE spectrometer were observed, giving guidelines for the design of an application specific integrated circuit (ASIC). The possibility of creating a solid state microdosemeter by coupling the ASIC with a tissue-equivalent radiator is discussed. Moreover, the p-i-n photodiode covered with a hydrogenated plastic radiator may be employed as a proton-recoil spectrometer.

  13. [Motion control of moving mirror based on fixed-mirror adjustment in FTIR spectrometer].

    PubMed

    Li, Zhong-bing; Xu, Xian-ze; Le, Yi; Xu, Feng-qiu; Li, Jun-wei

    2012-08-01

    The performance of the uniform motion of the moving mirror, which is the only constant motion part in FTIR spectrometer, and the performance of the alignment of the fixed mirror play a key role in FTIR spectrometer, and affect the interference effect and the quality of the spectrogram and may restrict the precision and resolution of the instrument directly. The present article focuses on the research on the uniform motion of the moving mirror and the alignment of the fixed mirror. In order to improve the FTIR spectrometer, the maglev support system was designed for the moving mirror and the phase detection technology was adopted to adjust the tilt angle between the moving mirror and the fixed mirror. This paper also introduces an improved fuzzy PID control algorithm to get the accurate speed of the moving mirror and realize the control strategy from both hardware design and algorithm. The results show that the development of the moving mirror motion control system gets sufficient accuracy and real-time, which can ensure the uniform motion of the moving mirror and the alignment of the fixed mirror.

  14. [Terahertz Absorption Spectra Simulation of Glutamine Based on Quantum-Chemical Calculation].

    PubMed

    Zhang, Tian-yao; Zhang, Zhao-hui; Zhao, Xiao-yan; Zhang, Han; Yan, Fang; Qian, Ping

    2015-08-01

    With simulation of absorption spectra in THz region based on quantum-chemical calculation, the THz absorption features of target materials can be assigned with theoretical normal vibration modes. This is necessary for deeply understanding the origin of THz absorption spectra. The reliabilities of simulation results mainly depend on the initial structures and theoretical methods used throughout the calculation. In our study, we utilized THz-TDS to obtain the THz absorption spectrum of solid-state L-glutamine. Then three quantum-chemical calculation schemes with different initial structures commonly used in previous studies were proposed to study the inter-molecular interactions' contribution to the THz absorption of glutamine, containing monomer structure, dimer structure and crystal unit cell structure. After structure optimization and vibration modes' calculation based on density functional theory, the calculation results were converted to absorption spectra by Lorentzian line shape function for visual comparison with experimental spectra. The result of dimmer structure is better than monomer structure in number of absorption features while worse than crystal unit cell structure in position of absorption peaks. With the most reliable simulation result from crystal unit cell calculation, we successfully assigned all three experimental absorption peaks of glutamine ranged from 0.3 to 2.6 THz with overall vibration modes. Our study reveals that the crystal unit cell should be used as initial structure during theoretical simulation of solid-state samples' THz absorption spectrum which comprehensively considers not only the intra-molecular interactions but also inter-molecular interactions.

  15. Observation of methane in this decade by ground-based FTIR Spectrometer over Poker Flat, ALASKA

    NASA Astrophysics Data System (ADS)

    Kasai, Y.; Kagawa, A.; Jones, N. B.; Murayama, Y.

    2010-12-01

    Tropospheric CH4 is an important greenhouse gas as second largest radiative forcing in the troposphere with a long lifetime of ~10 years (Rinsland et. al., 2005). Poker Flat is a suitable location to detect CH4 abnormally due to Siberian/Alaskan biomass burning (Kasai et. al., 2005), volcano, and an anthropogenical emissions such as gas leakage from pipe-lines. We have been observed troposheric CH4 over 10 years between 2000-2010 by using ground-based spectroscopic infrared solar absorption remote sensing measurement over Poker Flat, ALASKA (65.11N, 147.42W, 0.61km). CH4 vertical profiles were obtained by using SFIT2 ver.3.9 which incorporates Rodgers’ formulation of the Optimal Estimation Method (OEM) with an iterative Newton scheme (Rodgers, 2000). Frequency region of the CH4 is used 2600-2900 cm-1 region with the resolution 0.036cm-1. Seasonal and annual variation of the tropospheric CH4 in this decades was obtained. Increasing trend of tropospheric CH4 was observed. Several enhancement and depletion events were also observed.

  16. a Decade-Spanning High-Resolution Asynchronous Optical Sampling Based Terahertz Time-Domain Spectrometer

    NASA Astrophysics Data System (ADS)

    Good, Jacob T.; Holland, Daniel; Finneran, Ian A.; Carroll, Brandon; Allodi, Marco A.; Blake, Geoffrey

    2015-06-01

    High-resolution ASynchronous OPtical Sampling (ASOPS) is a technique that substantially improves the combined frequency resolution and bandwidth of ASOPS based TeraHertz Time-Domain Spectroscopy (THz-TDS) systems. We employ two mode-locked femtosecond Ti:Sapphire oscillators with repetition frequencies of 80 MHz operating at a fixed repetition frequency offset of 100 Hz. This offset lock is maintained by a Phase-Locked Loop (PLL) operating at the 60th harmonic of the repetition rate of the Ti:Sapphire oscillators. Their respective time delay is scanned across 12.5 ns requiring a scan time of 10 ms, supporting a time delay resolution of up to 15.6 fs. ASOPS-THz-TDS enables high-resolution spectroscopy that is impossible for a THz-TDS system employing a mechanical delay stage. We measure a timing jitter of 1.36 fs for the system using an air-gap etalon and an optical cross-correlator. We report a Root-Mean-Square deviation of 20.7 MHz and a mean deviation of 14.4 MHz for water absorption lines from 0.5 to 2.7. High-resolution ASOPS-THz-TDS enables high resolution spectroscopy of both gas-phase and condensed-phase samples across a decade of THz bandwidth.

  17. Hollow-fiber membrane-based rapid pressure swing absorption

    SciTech Connect

    Bhaumik, S.; Majumdar, S.; Sirkar, K.K.

    1996-02-01

    A novel gas purification technique called rapid pressure swing absorption (RAPSAB) was developed by integrating the best features of membrane contacting, gas-liquid absorption, and pressure swing adsorption (PSA). In this cyclic separation process, a well-packed microporous hydrophobic hollow-fiber module was used to achieve nondispersive gas absorption from a high-pressure feed gas into a stationary absorbent liquid on the module shell side during a certain part of the cycle followed by desorption of absorbed gases from the liquid in the rest of the cycle. The total cycle time varies between 20 s and upwards. Separation of mixtures of N{sub 2} and CO{sub 2} (around 10%) where CO{sub 2} is the impurity to be removed was studied using absorbent liquids such as pure water and a 19.5% aqueous solution of diethanolamine (DEA). Three RAPSAB cycles studied differ in the absorption part. Virtually pure N{sub 2} streams were obtained with DEA as absorbent demonstrating the capability of bulk separation to very high levels of purification. Numerical models developed predict the extent of purification for pure water and the DEA solution for one of the simpler cycles. Model simulations describe the observed behavior well.

  18. EM absorption reduction in wireless mobile antenna using printed paper-based metamaterial

    NASA Astrophysics Data System (ADS)

    Alam, Touhidul; Islam, Mohammad Tariqul; Kibria, Salehin; Cho, Mengu; Faruque, Mohammad Rashed Iqbal

    2017-01-01

    This paper presents a printed negative index metamaterial for electromagnetic (EM) absorption reduction in portable wireless antenna. The perceptible novelty exhibited in this paper is that EM absorption reduction toward the human head with paper-based metamaterial attachment. This research has been performed using human head phantom integrated in the commercially available CST Microwave Studio software package. The EM absorption has been reduced by 13.2 and 6% at 900 and 1800 MHz, respectively.

  19. HISS spectrometer

    SciTech Connect

    Greiner, D.E.

    1984-11-01

    This talk describes the Heavy Ion Spectrometer System (HISS) facility at the Lawrence Berkeley Laboratory's Bevalac. Three completed experiments and their results are illustrated. The second half of the talk is a detailed discussion of the response of drift chambers to heavy ions. The limitations of trajectory measurement over a large range in incident particle charge are presented.

  20. A colloidal quantum dot spectrometer

    NASA Astrophysics Data System (ADS)

    Bao, Jie; Bawendi, Moungi G.

    2015-07-01

    Spectroscopy is carried out in almost every field of science, whenever light interacts with matter. Although sophisticated instruments with impressive performance characteristics are available, much effort continues to be invested in the development of miniaturized, cheap and easy-to-use systems. Current microspectrometer designs mostly use interference filters and interferometric optics that limit their photon efficiency, resolution and spectral range. Here we show that many of these limitations can be overcome by replacing interferometric optics with a two-dimensional absorptive filter array composed of colloidal quantum dots. Instead of measuring different bands of a spectrum individually after introducing temporal or spatial separations with gratings or interference-based narrowband filters, a colloidal quantum dot spectrometer measures a light spectrum based on the wavelength multiplexing principle: multiple spectral bands are encoded and detected simultaneously with one filter and one detector, respectively, with the array format allowing the process to be efficiently repeated many times using different filters with different encoding so that sufficient information is obtained to enable computational reconstruction of the target spectrum. We illustrate the performance of such a quantum dot microspectrometer, made from 195 different types of quantum dots with absorption features that cover a spectral range of 300 nanometres, by measuring shifts in spectral peak positions as small as one nanometre. Given this performance, demonstrable avenues for further improvement, the ease with which quantum dots can be processed and integrated, and their numerous finely tuneable bandgaps that cover a broad spectral range, we expect that quantum dot microspectrometers will be useful in applications where minimizing size, weight, cost and complexity of the spectrometer are critical.

  1. Stabilization of Mass Absorption Cross Section of Elemental Carbon for Filter-Based Absorption Photometer by Heated Inlet

    NASA Astrophysics Data System (ADS)

    Kondo, Y.; Sahu, L.; Takegawa, N.; Miyazaki, Y.; Han, S.; Moteki, N.; Hu, M.; Kim Oanh, N.; Kim, Y.

    2008-12-01

    Accurate measurements of elemental carbon (EC) or black carbon on a long-term basis are important for the studies of impacts of EC on climate and human health. In principle, mass concentrations of EC (MEC) can be estimated by the measurement of light absorption coefficient by EC. Filter-based methods, which quantify the absorption coefficient (kabs) from the change in transmission through a filter loaded with particles, have been widely used to measure MEC because of the ease of the operation. However, in practice, reliable determination of MEC has been very difficult because of the large variability in the mass absorption cross sections (Cabs), which is a conversion factor from kabs to MEC. Coating of EC by volatile compounds and co-existence of light-scattering particles greatly contributes to the variability of Cabs. In order to overcome this difficulty, volatile aerosol components were removed before collection of EC particles on filters by heating an inlet section to 400°C. The heated inlet vaporized almost completely sulfate, nitrate, ammonium, and organics without any detectable loss of EC. Simultaneous measurements of kabs by two types photometers (Particle Soot Absorption Photometer (PSAP) and Continuous Soot Monitoring System (COSMOS)) together with MEC by the EC-OC analyzer were made to determine Cabs at 6 different locations in Asia (Japan, Korea, China, and Thailand) in different seasons. The Cabs was stable to be 10.5±0.7 m2 g-1 at the wavelength of 565 nm for EC strongly impacted by emissions from vehicles and biomass burning. The stability of the Cabs for different EC sources and under the different physical and chemical conditions provides a firm basis for its use in estimating MEC in fine mode with an accuracy of about 10%.

  2. Solar-based comparison of adsorption and absorption refrigerating machines

    NASA Astrophysics Data System (ADS)

    Ahachad, M.; Almers, A.; Mimet, A.; Draoui, A.

    2005-12-01

    This article attempts to carry out a computer simulation of an aqua-ammonia vapour absorption system, and an activated carbon ammonia adsorption system, with a 1m2 collector area, under climatic conditions of Tangier, north Morocco. This study is very important in order to point out the conditions that make the performance of one cycle superior to the other. The comparison of the performance of sorption cycle is still a difficult academic challenge because some part of the sorption cycle is still at the R&D stage. The effect of operating variables such as generator temperature, condenser temperature and evaporator temperature on the system performance is investigated. This study shows that, in solar applications, the adsorption system is better than the absorption system for several reasons including its efficiency, and that it is simple to operate.

  3. A High Spectral Resolution Lidar Based on Absorption Filter

    NASA Technical Reports Server (NTRS)

    Piironen, Paivi

    1996-01-01

    A High Spectral Resolution Lidar (HSRL) that uses an iodine absorption filter and a tunable, narrow bandwidth Nd:YAG laser is demonstrated. The iodine absorption filter provides better performance than the Fabry-Perot etalon that it replaces. This study presents an instrument design that can be used a the basis for a design of a simple and robust lidar for the measurement of the optical properties of the atmosphere. The HSRL provides calibrated measurements of the optical properties of the atmospheric aerosols. These observations include measurements of aerosol backscatter cross sections, optical depth, backscatter phase function depolarization, and multiple scattering. The errors in the HSRL data are discussed and the effects of different errors on the measured optical parameters are shown.

  4. Ultrasensitive optical absorption in graphene based on bound states in the continuum

    PubMed Central

    Zhang, Mingda; Zhang, Xiangdong

    2015-01-01

    We have designed a sphere-graphene-slab structure so that the electromagnetic wave can be well confined in the graphene due to the formation of a bound state in a continuum (BIC) of radiation modes. Based on such a bound state, we have realized strong optical absorption in the monolayer graphene. Such a strong optical absorption exhibits many advantages. It is ultrasensitive to the wavelength because the Q factor of the absorption peak can be more than 2000. By taking suitable BICs, the selective absorption for S and P waves has not only been realized, but also all-angle absorption for the S and P waves at the same time has been demonstrated. We have also found that ultrasensitive strong absorptions can appear at any wavelength from mid-infrared to far-infrared band. These phenomena are very beneficial to biosensing, perfect filters and waveguides. PMID:25652437

  5. Development of Novel Mid-Infrared Spectrometers Based on Quantum Cascade Lasers

    NASA Astrophysics Data System (ADS)

    Wang, Yin

    quality and reduces the manufacturing cost. These studies led to a better understanding of operation of Fabry-Perot (FP) QCLs, and allowed for development of a mid-IR spectroscopy based on multi-heterodyne of two FP-QCLs. Molecular absorption profile is down-converted into the RF spectrum by the heterodyne process. Both a multi-mode spectral retrieval and a high-resolution spectral scan capability based on the RF signal analysis are demonstrated.

  6. Compact spectrometer system based on a gradient grating period guided-mode resonance filter.

    PubMed

    Lin, Hsin-An; Hsu, Hsin-Yun; Chang, Chih-Wei; Huang, Cheng-Sheng

    2016-05-16

    We demonstrate a compact spectrometer system by using a gradient grating period guided-mode resonance filter-mounted on a linear photodetector array-that exhibits spatially dependent resonance characteristics; a specific incident wavelength is reflected such that the underlying array pixels measure minimum intensity. A precalibrated transmission efficiency matrix is used to determine each pixel's transmission efficiency for specific wavelengths. Unknown spectral information can be calculated from the measured intensity. Grating periods of 250-388 nm in 2-nm increments are used in each 100-cycle period. Device length is 2.23 mm. Spectral range of 506-700 nm is measurable with 1-nm resolution.

  7. Variations in thermospheric composition: A model based on mass-spectrometer and satellite-drag data

    NASA Technical Reports Server (NTRS)

    Jacchia, L. G.

    1973-01-01

    The seasonal-latitudinal and the diurnal variations of composition observed by mass spectrometers on the OGO 6 satellite are represented by two simple empirical formulae, each of which uses only one numerical parameter. The formulae are of a very general nature and predict the behavior of these variations at all heights and for all levels of solar activity; they yield a satisfactory representation of the corresponding variations in total density as derived from satellite drag. It is suggested that a seasonal variation of hydrogen might explain the abnormally low hydrogen densities at high northern latitudes in July 1964.

  8. A Web-Based Search Service to Support Imaging Spectrometer Instrument Operations

    NASA Technical Reports Server (NTRS)

    Smith, Alexander; Thompson, David R.; Sayfi, Elias; Xing, Zhangfan; Castano, Rebecca

    2013-01-01

    Imaging spectrometers yield rich and informative data products, but interpreting them demands time and expertise. There is a continual need for new algorithms and methods for rapid first-draft analyses to assist analysts during instrument opera-tions. Intelligent data analyses can summarize scenes to draft geologic maps, searching images to direct op-erator attention to key features. This validates data quality while facilitating rapid tactical decision making to select followup targets. Ideally these algorithms would operate in seconds, never grow bored, and be free from observation bias about the kinds of mineral-ogy that will be found.

  9. FINGERPRINTING INORGANIC ARSENIC AND ORGANOARSENIC COMPOUNDS IN IN SITU OIL SHALE RETORT AND PROCESS VOTERS USING A LIQUID CHROMATOGRAPH COUPLED WITH AN ATOMIC ABSORPTION SPECTROMETER AS A DETECTOR

    SciTech Connect

    Fish, Richard H.; Brinckman, Frederick E.; Jewett, Kenneth L.

    1981-07-01

    Inorganic arsenic and organoarsenic compounds were speciated in seven oil shale retort and process waters, including samples from simulated, true and modified in situ processes, using a high performance liquid chromatograph automatically coupled to a graphite furnace atomic absorption detector. The molecular forms of arsenic at ppm levels (({micro}g/mL) in these waters are identified for the first time, and shown to include arsenate, methylarsonic acid and phenylarsonic acid. An arsenic-specific fingerprint chromatogram of each retort or process water studied has significant impliestions regarding those arsenical species found and those marginally detected, such as dimethylarsinic acid and the suspected carcinogen arsenite. The method demonstrated suggests future means for quantifying environmental impacts of bioactive organometal species involved in oil shale retorting technology.

  10. Lidar reflectance from snow at 2.05  μm wavelength as measured by the JPL Airborne Laser Absorption Spectrometer.

    PubMed

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

    2016-03-10

    We report airborne measurements of lidar directional reflectance (backscatter) from land surfaces at a wavelength in the 2.05 μm CO₂ absorption band, with emphasis on snow-covered surfaces in various natural environments. Lidar backscatter measurements using this instrument provide insight into the capabilities of lidar for both airborne and future global-scale CO₂ measurements from low Earth orbit pertinent to the NASA Active Sensing of CO₂ Emissions over Nights, Days, and Seasons mission. Lidar measurement capability is particularly useful when the use of solar scattering spectroscopy is not feasible for high-accuracy atmospheric CO₂ measurements. Consequently, performance in high-latitude and winter season environments is an emphasis. Snow-covered surfaces are known to be dark in the CO₂ band spectral regions. The quantitative backscatter data from these field measurements help to elucidate the range of backscatter values that can be expected in natural environments.

  11. Far-infrared sensor for cirrus (FIRSC): an aircraft-based Fourier-transform spectrometer to measure cloud radiance.

    PubMed

    Vanek, M D; Nolt, I G; Tappan, N D; Ade, P A; Gannaway, F C; Hamilton, P A; Lee, C; Davis, J E; Predko, S

    2001-05-01

    We describe an aircraft-based Fourier-transform spectrometer (FTS) designed to measure the Earth outgoing radiance spectrum in the far-infrared-submillimeter spectral range. The instrument features include a rapid-scan FTS to obtain high spatial resolution from a moving aircraft platform, a sensitive two-channel detector, and a CCD camera for recording the nadir cloud scene with each scan record. Such measurements demonstrate the sensitivity of Earth radiance to high clouds and provide spectral data for improving techniques for remote sensing and retrieval of atmospheric and cloud properties.

  12. A portable and wide energy range semiconductor-based neutron spectrometer

    NASA Astrophysics Data System (ADS)

    Hoshor, C. B.; Oakes, T. M.; Myers, E. R.; Rogers, B. J.; Currie, J. E.; Young, S. M.; Crow, J. A.; Scott, P. R.; Miller, W. H.; Bellinger, S. L.; Sobering, T. J.; Fronk, R. G.; Shultis, J. K.; McGregor, D. S.; Caruso, A. N.

    2015-12-01

    Hand-held instruments that can be used to passively detect and identify sources of neutron radiation-either bare or obscured by neutron moderating and/or absorbing material(s)-in real time are of interest in a variety of nuclear non-proliferation and health physics applications. Such an instrument must provide a means to high intrinsic detection efficiency and energy-sensitive measurements of free neutron fields, for neutrons ranging from thermal energies to the top end of the evaporation spectrum. To address and overcome the challenges inherent to the aforementioned applications, four solid-state moderating-type neutron spectrometers of varying cost, weight, and complexity have been designed, fabricated, and tested. The motivation of this work is to introduce these novel human-portable instruments by discussing the fundamental theory of their operation, investigating and analyzing the principal considerations for optimal instrument design, and evaluating the capability of each of the four fabricated spectrometers to meet the application needs.

  13. The Spectrometer

    NASA Astrophysics Data System (ADS)

    Greenslade, Thomas B.

    2012-03-01

    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 technology. In this paper I would like to discuss its ancestors.

  14. 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…

  15. Measurement comparison among time-domain, FTIR and VNA-based spectrometers in the THz frequency range

    NASA Astrophysics Data System (ADS)

    Oberto, L.; Bisi, M.; Kazemipour, A.; Steiger, A.; Kleine-Ostmann, T.; Schrader, T.

    2017-02-01

    In this paper we present the outcome of the first international comparison in the terahertz frequency range among three different kinds of spectrometers. A Fourier-Transform infrared spectrometer, a vector network analyzer and a time-domain spectrometer have been employed for measuring the complex refractive index of three travelling standards made of selected dielectric materials in order to offer a wide enough range of parameters to be measured. The three spectrometers have been compared in terms of measurement capability and uncertainty.

  16. A complete diet-based algorithm for predicting nonheme iron absorption in adults.

    PubMed

    Armah, Seth M; Carriquiry, Alicia; Sullivan, Debra; Cook, James D; Reddy, Manju B

    2013-07-01

    Many algorithms have been developed in the past few decades to estimate nonheme iron absorption from the diet based on single meal absorption studies. Yet single meal studies exaggerate the effect of diet and other factors on absorption. Here, we propose a new algorithm based on complete diets for estimating nonheme iron absorption. We used data from 4 complete diet studies each with 12-14 participants for a total of 53 individuals (19 men and 34 women) aged 19-38 y. In each study, each participant was observed during three 1-wk periods during which they consumed different diets. The diets were typical, high, or low in meat, tea, calcium, or vitamin C. The total sample size was 159 (53 × 3) observations. We used multiple linear regression to quantify the effect of different factors on iron absorption. Serum ferritin was the most important factor in explaining differences in nonheme iron absorption, whereas the effect of dietary factors was small. When our algorithm was validated with single meal and complete diet data, the respective R(2) values were 0.57 (P < 0.001) and 0.84 (P < 0.0001). The results also suggest that between-person variations explain a large proportion of the differences in nonheme iron absorption. The algorithm based on complete diets we propose is useful for predicting nonheme iron absorption from the diets of different populations.

  17. Algorithm development for predicting biodiversity based on phytoplankton absorption

    NASA Astrophysics Data System (ADS)

    Moisan, Tiffany A. H.; Moisan, John R.; Linkswiler, Matthew A.; Steinhardt, Rachel A.

    2013-03-01

    Ocean color remote sensing has provided the scientific community with unprecedented global coverage of chlorophyll a, an indicator of phytoplankton biomass. Together, satellite-derived chlorophyll a and knowledge of Phytoplankton Functional Types (PFTs) will improve our limited understanding of marine ecosystem responses to physiochemical climate drivers involved in carbon cycle dynamics and linkages. Using cruise data from the Gulf of Maine and the Middle Atlantic Bight (N=269 pairs of HPLC and phytoplankton absorption samples), two modeling approaches were utilized to predict phytoplankton absorption and pigments. Algorithm I predicts the chlorophyll-specific absorption coefficient (aph* (m2 mg chl a-1)) using inputs of temperature, light, and chlorophyll a. Modeled r2 values (400-700 nm) ranged from 0.79 to 0.99 when compared to in situ observations with ˜25% lower r2 values in the UV region. Algorithm II-a utilizes matrix inversion analysis to predict a(m-1, 400-700 nm) and r2 values ranged from 0.89 to 0.99. The prediction of phytoplankton pigments with Algorithm II-b produced r2 values that ranged from 0.40 to 0.93. When used in combination, Algorithm I, and Algorithm II-a are able to use satellite products of SST, PAR, and chlorophyll a (Algorithm I) to predict pigment concentrations and ratios to describe the phytoplankton community. The results of this study demonstrate that the spatial variation in modeled pigment ratios differ significantly from the 10-year SeaWiFS average chlorophyll a data set. Contiguous observations of chlorophyll a and phytoplankton biodiversity will elucidate ecosystem responses with unprecedented complexity.

  18. Hydrogen Absorption in Pd-based Nanostructures - Final Report

    SciTech Connect

    David Lederman

    2012-10-22

    Pd is known to absorb hydrogen. Molecules are normally chemisorbed at the surface in a process where the molecule breaks into two hydrogen atoms, and the protons are then absorbed into the bulk. This process consists of electron filling holes in the Pd 4d band near the Fermi energy, which due to the high density of states at the Fermi energy, is an energetically favorable process. Our aim with this project was to determine possible changes in magnetic properties with Pd nm-length-scale thick layers intercalated by magnetic materials. Before the start of this work, the literature indicated that there were several possible scenarios by which this could happen: i) the Pd will be magnetized due to a proximity effect with nearby magnetic layers, resulting in changes in the magnetization due to H2 absorption; ii) some H will be absorbed into the magnetic layers, causing a change in the magnetic exchange interactions; or iii) absorption of H2 will cause an expansion of the lattice, resulting in a magnetoelastic effect which changes the magnetic properties.

  19. Radiometric Modeling and Calibration of the Geostationary Imaging Fourier Transform Spectrometer (GIFTS)Ground Based Measurement Experiment

    NASA Technical Reports Server (NTRS)

    Tian, Jialin; Smith, William L.; Gazarik, Michael J.

    2008-01-01

    The ultimate remote sensing benefits of the high resolution Infrared radiance spectrometers will be realized with their geostationary satellite implementation in the form of imaging spectrometers. This will enable dynamic features of the atmosphere s thermodynamic fields and pollutant and greenhouse gas constituents to be observed for revolutionary improvements in weather forecasts and more accurate air quality and climate predictions. As an important step toward realizing this application objective, the Geostationary Imaging Fourier Transform Spectrometer (GIFTS) Engineering Demonstration Unit (EDU) was successfully developed under the NASA New Millennium Program, 2000-2006. The GIFTS-EDU instrument employs three focal plane arrays (FPAs), which gather measurements across the long-wave IR (LWIR), short/mid-wave IR (SMWIR), and visible spectral bands. The GIFTS calibration is achieved using internal blackbody calibration references at ambient (260 K) and hot (286 K) temperatures. In this paper, we introduce a refined calibration technique that utilizes Principle Component (PC) analysis to compensate for instrument distortions and artifacts, therefore, enhancing the absolute calibration accuracy. This method is applied to data collected during the GIFTS Ground Based Measurement (GBM) experiment, together with simultaneous observations by the accurately calibrated AERI (Atmospheric Emitted Radiance Interferometer), both simultaneously zenith viewing the sky through the same external scene mirror at ten-minute intervals throughout a cloudless day at Logan Utah on September 13, 2006. The accurately calibrated GIFTS radiances are produced using the first four PC scores in the GIFTS-AERI regression model. Temperature and moisture profiles retrieved from the PC-calibrated GIFTS radiances are verified against radiosonde measurements collected throughout the GIFTS sky measurement period. Using the GIFTS GBM calibration model, we compute the calibrated radiances from data

  20. A peripheral component interconnect express-based scalable and highly integrated pulsed spectrometer for solution state dynamic nuclear polarization

    SciTech Connect

    He, Yugui; Liu, Chaoyang; Feng, Jiwen; Wang, Dong; Chen, Fang; Liu, Maili; Zhang, Zhi; Wang, Chao

    2015-08-15

    High sensitivity, high data rates, fast pulses, and accurate synchronization all represent challenges for modern nuclear magnetic resonance spectrometers, which make any expansion or adaptation of these devices to new techniques and experiments difficult. Here, we present a Peripheral Component Interconnect Express (PCIe)-based highly integrated distributed digital architecture pulsed spectrometer that is implemented with electron and nucleus double resonances and is scalable specifically for broad dynamic nuclear polarization (DNP) enhancement applications, including DNP-magnetic resonance spectroscopy/imaging (DNP-MRS/MRI). The distributed modularized architecture can implement more transceiver channels flexibly to meet a variety of MRS/MRI instrumentation needs. The proposed PCIe bus with high data rates can significantly improve data transmission efficiency and communication reliability and allow precise control of pulse sequences. An external high speed double data rate memory chip is used to store acquired data and pulse sequence elements, which greatly accelerates the execution of the pulse sequence, reduces the TR (time of repetition) interval, and improves the accuracy of TR in imaging sequences. Using clock phase-shift technology, we can produce digital pulses accurately with high timing resolution of 1 ns and narrow widths of 4 ns to control the microwave pulses required by pulsed DNP and ensure overall system synchronization. The proposed spectrometer is proved to be both feasible and reliable by observation of a maximum signal enhancement factor of approximately −170 for {sup 1}H, and a high quality water image was successfully obtained by DNP-enhanced spin-echo {sup 1}H MRI at 0.35 T.

  1. A peripheral component interconnect express-based scalable and highly integrated pulsed spectrometer for solution state dynamic nuclear polarization

    NASA Astrophysics Data System (ADS)

    He, Yugui; Feng, Jiwen; Zhang, Zhi; Wang, Chao; Wang, Dong; Chen, Fang; Liu, Maili; Liu, Chaoyang

    2015-08-01

    High sensitivity, high data rates, fast pulses, and accurate synchronization all represent challenges for modern nuclear magnetic resonance spectrometers, which make any expansion or adaptation of these devices to new techniques and experiments difficult. Here, we present a Peripheral Component Interconnect Express (PCIe)-based highly integrated distributed digital architecture pulsed spectrometer that is implemented with electron and nucleus double resonances and is scalable specifically for broad dynamic nuclear polarization (DNP) enhancement applications, including DNP-magnetic resonance spectroscopy/imaging (DNP-MRS/MRI). The distributed modularized architecture can implement more transceiver channels flexibly to meet a variety of MRS/MRI instrumentation needs. The proposed PCIe bus with high data rates can significantly improve data transmission efficiency and communication reliability and allow precise control of pulse sequences. An external high speed double data rate memory chip is used to store acquired data and pulse sequence elements, which greatly accelerates the execution of the pulse sequence, reduces the TR (time of repetition) interval, and improves the accuracy of TR in imaging sequences. Using clock phase-shift technology, we can produce digital pulses accurately with high timing resolution of 1 ns and narrow widths of 4 ns to control the microwave pulses required by pulsed DNP and ensure overall system synchronization. The proposed spectrometer is proved to be both feasible and reliable by observation of a maximum signal enhancement factor of approximately -170 for 1H, and a high quality water image was successfully obtained by DNP-enhanced spin-echo 1H MRI at 0.35 T.

  2. Soft X-Ray (1-7 nm) Solar Spectrometer based on novel Nanowriter Electron-Beam Nanofabrication Technology

    NASA Astrophysics Data System (ADS)

    Didkovsky, L. V.; Wieman, S. R.; Chao, W.

    2015-12-01

    A new soft X-ray (SXR) spectrometer combines proven detector technology demonstrated on the SOHO Solar EUV Monitor (SOHO/SEM) and SDO EUV SpectroPhotometer (SDO/EVE/ESP) instruments with novel technology for X-ray optics nanofabrication developed at the Lawrence Berkeley National Laboratory. The new spectrometer will provide solar SXR measurements of absolute irradiance in the 1.0 to 7.0 nm range spectrally resolved into bands narrower than 1 nm - measurements that are not available from existing solar-observing instruments but are important for studying and modeling coronal dynamics and the Sun-Earth's connection, e.g. the Earth's Ionosphere. For the proposed SXR spectrometer we will introduce a transmission grating based on novel Nanowriter Electron-Beam Nanofabrication technology developed at the Center for X-ray Optics (CXRO) at the Lawrence Berkeley National Laboratory. The CXRO technology has been used in the fabrication of X-ray zone plates with feature sizes as small as 25 nm in optical elements with overall sizes on the order of 1 cm. The CXRO technology has significant flexibility in terms of pattern geometry, and is thus capable of producing linear transmission gratings with aperture sizes similar to SEM and ESP but with four times the dispersion. With such dispersion, reasonable spectral resolution (< 1nm) can be obtained using commercial off-the shelf (COTS) X-ray sensitive AXUV type silicon photodiodes from the Optodiode Corp. in an instrument with overall size and mass similar to that of SEM or ESP.

  3. Using Raman-lidar-based regularized microphysical retrievals and Aerosol Mass Spectrometer measurements for the characterization of biomass burning aerosols

    NASA Astrophysics Data System (ADS)

    Samaras, Stefanos; Nicolae, Doina; Böckmann, Christine; Vasilescu, Jeni; Binietoglou, Ioannis; Labzovskii, Lev; Toanca, Florica; Papayannis, Alexandros

    2015-10-01

    In this work we extract the microphysical properties of aerosols for a collection of measurement cases with low volume depolarization ratio originating from fire sources captured by the Raman lidar located at the National Institute of Optoelectronics (INOE) in Bucharest. Our algorithm was tested not only for pure smoke but also for mixed smoke and urban aerosols of variable age and growth. Applying a sensitivity analysis on initial parameter settings of our retrieval code was proved vital for producing semi-automatized retrievals with a hybrid regularization method developed at the Institute of Mathematics of Potsdam University. A direct quantitative comparison of the retrieved microphysical properties with measurements from a Compact Time of Flight Aerosol Mass Spectrometer (CToF-AMS) is used to validate our algorithm. Microphysical retrievals performed with sun photometer data are also used to explore our results. Focusing on the fine mode we observed remarkable similarities between the retrieved size distribution and the one measured by the AMS. More complicated atmospheric structures and the factor of absorption appear to depend more on particle radius being subject to variation. A good correlation was found between the aerosol effective radius and particle age, using the ratio of lidar ratios (LR: aerosol extinction to backscatter ratios) as an indicator for the latter. Finally, the dependence on relative humidity of aerosol effective radii measured on the ground and within the layers aloft show similar patterns.

  4. Development and operation of a high-throughput accurate-wavelength lens-based spectrometer

    SciTech Connect

    Bell, Ronald E.

    2014-11-15

    A high-throughput spectrometer for the 400–820 nm wavelength range has been developed for charge exchange recombination spectroscopy or general spectroscopy. A large 2160 mm{sup −1} grating is matched with fast f/1.8 200 mm lenses, which provide stigmatic imaging. A precision optical encoder measures the grating angle with an accuracy ≤0.075 arc sec. A high quantum efficiency low-etaloning CCD detector allows operation at longer wavelengths. A patch panel allows input fibers to interface with interchangeable fiber holders that attach to a kinematic mount at the entrance slit. Computer-controlled hardware allows automated control of wavelength, timing, f-number, automated data collection, and wavelength calibration.

  5. Invited Article: Characterization of background sources in space-based time-of-flight mass spectrometers

    SciTech Connect

    Gilbert, J. A.; Gershman, D. J.; Gloeckler, G.; Lundgren, R. A.; Zurbuchen, T. H.; Orlando, T. M.; McLain, J.; Steiger, R. von

    2014-09-15

    For instruments that use time-of-flight techniques to measure space plasma, there are common sources of background signals that evidence themselves in the data. The background from these sources may increase the complexity of data analysis and reduce the signal-to-noise response of the instrument, thereby diminishing the science value or usefulness of the data. This paper reviews several sources of background commonly found in time-of-flight mass spectrometers and illustrates their effect in actual data using examples from ACE-SWICS and MESSENGER-FIPS. Sources include penetrating particles and radiation, UV photons, energy straggling and angular scattering, electron stimulated desorption of ions, ion-induced electron emission, accidental coincidence events, and noise signatures from instrument electronics. Data signatures of these sources are shown, as well as mitigation strategies and design considerations for future instruments.

  6. Invited article: Characterization of background sources in space-based time-of-flight mass spectrometers.

    PubMed

    Gilbert, J A; Gershman, D J; Gloeckler, G; Lundgren, R A; Zurbuchen, T H; Orlando, T M; McLain, J; von Steiger, R

    2014-09-01

    For instruments that use time-of-flight techniques to measure space plasma, there are common sources of background signals that evidence themselves in the data. The background from these sources may increase the complexity of data analysis and reduce the signal-to-noise response of the instrument, thereby diminishing the science value or usefulness of the data. This paper reviews several sources of background commonly found in time-of-flight mass spectrometers and illustrates their effect in actual data using examples from ACE-SWICS and MESSENGER-FIPS. Sources include penetrating particles and radiation, UV photons, energy straggling and angular scattering, electron stimulated desorption of ions, ion-induced electron emission, accidental coincidence events, and noise signatures from instrument electronics. Data signatures of these sources are shown, as well as mitigation strategies and design considerations for future instruments.

  7. Development and Operation of High-throughput Accurate-wavelength Lens-based Spectrometer

    SciTech Connect

    Bell, Ronald E

    2014-07-01

    A high-throughput spectrometer for the 400-820 nm wavelength range has been developed for charge exchange recombination spectroscopy or general spectroscopy. A large 2160 mm-1 grating is matched with fast f /1.8 200 mm lenses, which provide stigmatic imaging. A precision optical encoder measures the grating angle with an accuracy < 0.075 arc seconds. A high quantum efficiency low-etaloning CCD detector allows operation at longer wavelengths. A patch panel allows input fibers to interface with interchangeable fiber holders that attach to a kinematic mount behind the entrance slit. Computer-controlled hardware allows automated control of wavelength, timing, f-number, automated data collection, and wavelength calibration.

  8. [Establishment and Improvement of Portable X-Ray Fluorescence Spectrometer Detection Model Based on Wavelet Transform].

    PubMed

    Li, Fang; Wang, Ji-hua; Lu, An-xiang; Han, Ping

    2015-04-01

    The concentration of Cr, Cu, Zn, As and Pb in soil was tested by portable X-ray fluorescence spectrometer. Each sample was tested for 3 times, then after using wavelet threshold noise filtering method for denoising and smoothing the spectra, a standard curve for each heavy metal was established according to the standard values of heavy metals in soil and the corresponding counts which was the average of the 3 processed spectra. The signal to noise ratio (SNR), mean square error (MSE) and information entropy (H) were taken to assess the effects of denoising when using wavelet threshold noise filtering method for determining the best wavelet basis and wavelet decomposition level. Some samples with different concentrations and H3 B03 (blank) were chosen to retest this instrument to verify its stability. The results show that: the best denoising result was obtained with the coif3 wavelet basis at the decomposition level of 3 when using the wavelet transform method. The determination coefficient (R2) range of the instrument is 0.990-0.996, indicating that a high degree of linearity was found between the contents of heavy metals in soil and each X-ray fluorescence spectral characteristic peak intensity with the instrument measurement within the range (0-1,500 mg · kg(-1)). After retesting and calculating, the results indicate that all the detection limits of the instrument are below the soil standards at national level. The accuracy of the model has been effectively improved, and the instrument also shows good precision with the practical application of wavelet transform to the establishment and improvement of X-ray fluorescence spectrometer detection model. Thus the instrument can be applied in on-site rapid screening of heavy metal in contaminated soil.

  9. Membrane-Based Absorption Refrigeration Systems: Nanoengineered Membrane-Based Absorption Cooling for Buildings Using Unconcentrated Solar & Waste Heat

    SciTech Connect

    2010-09-01

    BEETIT Project: UFL is improving a refrigeration system that uses low quality heat to provide the energy needed to drive cooling. This system, known as absorption refrigeration system (ARS), typically consists of large coils that transfer heat. Unfortunately, these large heat exchanger coils are responsible for bulkiness and high cost of ARS. UFL is using new materials as well as system design innovations to develop nanoengineered membranes to allow for enhanced heat exchange that reduces bulkiness. UFL’s design allows for compact, cheaper and more reliable use of ARS that use solar or waste heat.

  10. Improved conversion efficiency of GaN-based solar cells with Mn-doped absorption layer

    NASA Astrophysics Data System (ADS)

    Sheu, Jinn-Kong; Huang, Feng-Wen; Lee, Chia-Hui; Lee, Ming-Lun; Yeh, Yu-Hsiang; Chen, Po-Cheng; Lai, Wei-Chih

    2013-08-01

    GaN-based solar cells with Mn-doped absorption layer grown by metal-organic vapor-phase epitaxy were investigated. The transmittance spectrum and the spectral response showed the presence of an Mn-related band absorption property. Power-dependent, dual-light excitation, and lock-in amplifier techniques were performed to confirm if the two-photon absorption process occurred in the solar cells with Mn-doped GaN absorption layer. Although a slight decrease in an open circuit voltage was observed, a prominent increase in the short circuit current density resulted in a significant enhancement of the overall conversion efficiency. Under one-sun air mass 1.5 G standard testing condition, the conversion efficiency of Mn-doped solar cells can be enhanced by a magnitude of 5 times compared with the cells without Mn-doped absorption layer.

  11. Comparison of imaging spectrometers

    SciTech Connect

    Bennett, C

    2000-01-09

    Realistic signal to noise performance estimates for the various types of instruments being considered for NGST are compared, based on the point source detection values quoted in the available ISIM final reports. The corresponding sensitivity of the various types of spectrometers operating in a full field imaging mode, for both emission line objects and broad spectral distribution objects, is computed and displayed. For the purpose of seeing the earliest galaxies, or the faintest possible emission line sources, the imaging Fourier transform spectrometer emerges superior to all others, by orders of magnitude in speed.

  12. Lunar Prospector neutron spectrometer constraints on TiO2

    NASA Astrophysics Data System (ADS)

    Elphic, R. C.; Lawrence, D. J.; Feldman, W. C.; Barraclough, B. L.; Gasnault, O. M.; Maurice, S.; Lucey, P. G.; Blewett, D. T.; Binder, A. B.

    2002-04-01

    Lunar Prospector neutron spectrometer measurements of the epithermal and thermal neutron leakage fluxes are used to provide constraints on TiO2 abundances in lunar surface materials. We use FeO abundance estimates based on both Clementine spectral reflectance techniques and preliminary Lunar Prospector gamma ray spectrometer determinations to first establish a model thermal neutron absorption due to all major elements except titanium. Then we remove the additional absorbing effects due to the rare earth elements gadolinium and samarium by using Lunar Prospector gamma ray spectrometer thorium abundances as a rare earth element proxy. The result can be compared to the ratio of epithermal to thermal neutron fluxes, which point to the presence of the additional thermal neutron absorber, titanium. We can derive abundance estimates of TiO2 and compare to other estimates derived spectroscopically. Our results show a significantly lower abundance of TiO2 than has been derived using Clementine data.

  13. 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.

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

    PubMed

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

    2012-12-21

    We investigated IR spectra in the CH- and SH-stretching regions of size-selected methanethiol clusters, (CH(3)SH)(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 (CH(3)SH)(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 (CH(3)SH)(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 (CH(3)SH)(n), n = 3-5, show a broad band near 2567 cm(-1) with much greater intensity. In the CH-stretching region, absorption bands of (CH(3)SH)(2) are located near 2865, 2890, 2944, and 3010 cm(-1), red-shifted by 3-5 cm(-1) from those of CH(3)SH. These red shifts increase slightly for larger clusters and bands near 2856, 2884, 2938, and 3005 cm(-1) were observed for (CH(3)SH)(5). These spectral results indicate that the S-H[middle dot][middle dot][middle dot]S hydrogen bond plays an important role in clusters with n = 3-5, but not in (CH(3)SH)(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 (CH(3)SH)(n), n = 3-5, have a cyclic hydrogen-bonded framework.

  15. MASS SPECTROMETER

    DOEpatents

    White, F.A.

    1960-08-23

    A mass spectrometer is designed with a first adjustable magnetic field for resolving an ion beam into beams of selected masses, a second adjustable magnetic field for further resolving the ion beam from the first field into beams of selected masses, a thin foil disposed in the path of the beam between the first and second magnets to dissociate molecular ions incident thereon, an electrostatic field for further resolving the ion beam from the second field into beams of selected masses, and a detector disposed adjacent to the electrostatic field to receive the ion beam.

  16. 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.

  17. Real-time monitoring of trace-level VOCs by an ultrasensitive compact lamp-based VUV photoionization mass spectrometer

    NASA Astrophysics Data System (ADS)

    Sun, W. Q.; Shu, J. N.; Zhang, P.; Li, Z.; Li, N. N.; Liang, M.; Yang, B.

    2015-06-01

    In this study, we report on the development of a compact lamp-based vacuum ultraviolet (VUV) photoionization mass spectrometer (PIMS; hereafter referred to as VUV-PIMS) in our laboratory; it is composed of a radio frequency-powered VUV lamp, a VUV photoionizer, an ion-immigration region, and a reflection time-of-flight mass spectrometer. By utilizing the novel photoionizer consisting of a photoionization cavity and a VUV light baffle, extremely low background noise was obtained. An ultrasensitive detection limit (2σ) of 3 pptv was achieved for benzene after an acquisition time of 10 s. To examine its potential for application in real-time sample monitoring, the developed VUV-PIMS was employed for the continuous measurement of urban air for six days in Beijing, China. Strong signals of trace-level volatile organic compounds such as benzene and its alkylated derivatives were observed in the mass spectra. These initial experimental results reveal that the instrument can be used for the online monitoring of trace-level species in the atmosphere.

  18. Ground-Based Measurement Experiment and First Results with Geosynchronous-Imaging Fourier Transform Spectrometer Engineering Demonstration Unit

    NASA Technical Reports Server (NTRS)

    Zhou, Daniel K.; Smith, William L.; Bingham, Gail E.; Huppi, Ronald J.; Revercomb, Henry E.; Zollinger, Lori J.; Larar, Allen M.; Liu, Xu; Tansock, Joseph J.; Reisse, Robert A.; Hooker, Ronald

    2007-01-01

    The geosynchronous-imaging Fourier transform spectrometer (GIFTS) engineering demonstration unit (EDU) is an imaging infrared spectrometer designed for atmospheric soundings. It measures the infrared spectrum in two spectral bands (14.6 to 8.8 microns, 6.0 to 4.4 microns) using two 128 x 128 detector arrays with a spectral resolution of 0.57 cm(exp -1) with a scan duration of approximately 11 seconds. From a geosynchronous orbit, the instrument will have the capability of taking successive measurements of such data to scan desired regions of the globe, from which atmospheric status, cloud parameters, wind field profiles, and other derived products can be retrieved. The GIFTS EDU provides a flexible and accurate testbed for the new challenges of the emerging hyperspectral era. The EDU ground-based measurement experiment, held in Logan, Utah during September 2006, demonstrated its extensive capabilities and potential for geosynchronous and other applications (e.g., Earth observing environmental measurements). This paper addresses the experiment objectives and overall performance of the sensor system with a focus on the GIFTS EDU imaging capability and proof of the GIFTS measurement concept.

  19. Spin exchange optical pumping based polarized {sup 3}He filling station for the Hybrid Spectrometer at the Spallation Neutron Source

    SciTech Connect

    Jiang, C. Y.; Tong, X.; Brown, D. R.; Culbertson, H.; Kadron, B.; Robertson, J. L.; Graves-Brook, M. K.; Hagen, M. E.; Lee, W. T.; Winn, B.

    2013-06-15

    The Hybrid Spectrometer (HYSPEC) is a new direct geometry spectrometer at the Spallation Neutron Source at the Oak Ridge National Laboratory. This instrument is equipped with polarization analysis capability with 60 Degree-Sign horizontal and 15 Degree-Sign vertical detector coverages. In order to provide wide angle polarization analysis for this instrument, we have designed and built a novel polarized {sup 3}He filling station based on the spin exchange optical pumping method. It is designed to supply polarized {sup 3}He gas to HYSPEC as a neutron polarization analyzer. In addition, the station can optimize the {sup 3}He pressure with respect to the scattered neutron energies. The depolarized {sup 3}He gas in the analyzer can be transferred back to the station to be repolarized. We have constructed the prototype filling station. Preliminary tests have been carried out demonstrating the feasibility of the filling station. Here, we report on the design, construction, and the preliminary results of the prototype filling station.

  20. Near UV-near IR Fourier transform spectrometer using the beam-folding position-tracking method based on retroreflectors.

    PubMed

    Wang, Xuzhu; Chan, Robert K Y; Cheng, Amelia S K

    2008-12-01

    A near UV-near IR Fourier transform spectrometer based on a beam-folding position-tracking method realized by using retroreflectors is reported. The use of retroreflectors maintains all beams in the beam-fold arrangement in parallel with the incident beams. The beam-folding interferometer used for position tracking is arranged to have optical path symmetry with the measurement interferometer in the zero path difference position of the measurement interferometer, and the vertex of the movable retroreflector in the measurement interferometer is arranged very close to the midpoint of the vertices of two movable retroreflectors in the position-tracking interferometer. These measures keep the equivalent optical axis of the position-tracking interferometer well in line with that of the measurement interferometer even with translational misalignments. Therefore, the change in the optical path difference of the position-tracking interferometer is always synchronous to that of the measurement interferometer during the scanning process. That is, the position-tracking error can be suppressed to very small values during a scan. We have demonstrated a UV-near IR Fourier transform spectrometer with a standard quality ball-bearing translation stage achieving a resolution close to the theoretical resolution of approximately 0.28 cm(-1) at the He-Ne laser wavelength when the scan distance reaches the travel distance of over 2 cm. This was achieved without the need for elaborate optics, sophisticated detecting electronics, and high-precision servomotion control.

  1. Fabrication and application of absorption-based and interference-based micropolarizers

    NASA Astrophysics Data System (ADS)

    Hsu, Wei-Liang

    The ability to create arbitrary patterned linear, circular, and elliptical liquid crystal polymer polarizers is demonstrated in this work. The operating wavelength of the thin-film polarizer ranges from 400 to 4200 nm. The linear absorption-based micropolarizer is fabricated using dichroic dye as a guest in liquid crystal polymer host with feature sizes as small as 4 mum. The circular interference-based micropolarizer is fabricated using cholesteric liquid crystal polymers with feature sizes as small as 6.2 mum. The elliptical micropolarizer is achieved using the combination of a microretarder and a micropolarizer. The chemistry, fabrication process, spatial resolution and optical properties of micropolarizers are presented. Alignments of liquid crystal polymers and cholesteric liquid crystal polymers are both achieved using photoalignment technique with polarized photo-lithography. Two different methods, thermal annealing and solvent rinse, are utilized for patterning cholesteric liquid crystal polymers over large areas. In addition to exploring absorption-based and interference-based micropolarizers, arrays of micropolarizers are fabricated for the construction of 580nm and 760nm division-of-focal-plane full-Stokes imaging polarimeters. The polarimeter utilizes a set of four optimized measurements which represent a regular tetrahedron inscribed in the Poincare sphere. Results from the device fabrication, instrument calibration and characterization for the 580 nm polarimeter are presented. The optimized imaging polarimeter can be used for sampling the polarization signature across a scene with a resolution of 1608 x 1208 x 14-bit at 20 frames/second.

  2. Measurements of stable isotope ratios ({sup 13}CH{sub 4}/{sup 12}CH{sub 4}; {sup 12}CH{sub 3}/{sup 12}CH{sub 3}) in landfill methane using a tunable diode laser absorption spectrometer

    SciTech Connect

    Bergmaschi, P.; Harris, G.W.

    1995-12-01

    Experiments were conducted to measure variations in the isotopic composition of methane (CH{sub 4}) produced by a municipal solid waste landfill in Germany. A tunable diode laser absorption spectrometer was used to determine isotopic ratios of {sup 13}CH{sub 4}/{sup 12}CH{sub 4} and {sup 12}CH{sub 3}D/{sup 12}CH{sub 4} in biogas samples taken directly from various branches of the gas collection system. The {delta}{sup 13} values for CH{sub 4} showed very small variations; however, the {delta}{sup 13} values for carbon dioxide C0{sub 2} were substantially larger. The {delta}D values of CH{sub 4} exhibited variations corresponding to samples taken from sections filled at different time periods. Oxygen consumption was correlated with the {delta}{sup 13}C and {delta}D of CH{sub 4} and the {delta}{sup 13}C of CO{sub 2} consistent with partial bacterial oxidation of methane. A negative correlation between {delta}D and {delta}{sup 13}C(CH{sub 4}) and between {delta}{sup 13}C(CO{sub 2}) and {delta}{sup 13}C(CH{sub 4}) in samples showing no oxidation was attributed to slightly varying contributions of CO{sub 2} reduction and acetate fermentation. 22 refs., 5 figs., 1 tab.

  3. [The Research for Trace Ammonia Escape Monitoring System Based on Tunable Diode Laser Absorption Spectroscopy].

    PubMed

    Zhang, Li-fang; Wang, Fei; Yu, Li-bin; Yan, Jian-hua; Cen, Ke-fa

    2015-06-01

    In order to on-line measure the trace ammonia slip of the commercial power plant in the future, this research seeks to measure the trace ammonia by using tunable diode laser absorption spectroscopy under ambient temperature and pressure, and at different temperatures, and the measuring temperature is about 650 K in the power plant. In recent years lasers have become commercially available in the near-infrared where the transitions are much stronger, and ammonia's spectroscopy is pretty complicated and the overlapping lines are difficult to resolve. A group of ammonia transitions near 4 433.5 cm(-1) in the v2 +v3 combination band have been thoroughly selected for detecting lower concentration by analyzing its absorption characteristic and considering other absorption interference in combustion gases where H2O and CO2 mole fraction are very large. To illustrate the potential for NH3 concentration measurements, predictions for NH3, H2O and CO2 are simultaneously simulated, NH3 absorption lines near 4 433.5 cm(-1) wavelength meet weaker H2O absorption than the commercial NH3 lines, and there is almost no CO2 absorption, all the parameters are based on the HITRAN database, and an improved detection limit was obtained for interference-free NH3 monitoring, this 2.25 μm band has line strengths several times larger than absorption lines in the 1.53 μm band which was often used by NH3 sensors for emission monitoring and analyzing. The measurement system was developed with a new Herriott cell and a heated gas cell realizing fast absorption measurements of high resolution, and combined with direct absorption and wavelenguh modulation based on tunable diode laser absorption spectroscopy at different temperatures. The lorentzian line shape is dominant at ambient temperature and pressure, and the estimated detectivity is approximately 0.225 x 10(-6) (SNR = 1) for the directed absorption spectroscopy, assuming a noise-equivalent absorbance of 1 x 10(-4). The heated cell

  4. Atmospheric HONO and NO2 measurement based on a broadband cavity enhanced UV-LED spectrometer

    NASA Astrophysics Data System (ADS)

    Wu, Tao; Zha, Qiaozhi; Chen, Weidong; Xu, Zheng; Wang, Tao; He, Xingdao

    2015-04-01

    Nitrous acid (HONO) is a key component in tropospheric oxidant chemistry due to its contribution to the cycles of nitrogen oxides (NOx) and hydrogen oxides (HOx). Though numerous laboratory, field, and modeling studies were performed to explain the observed HONO concentrations in the atmosphere, the knowledge of atmospheric HONO chemistry is still not well understood and sometimes controversial [1]. Accurate measurements of HONO and its precursors with high precision should aid in understanding the HONO chemistry. In this paper we report on the measurements of HONO and NO2 concentrations at a suburban site of Tung Chung in Hong Kong during a field intercomparison campaign using a broadband cavity enhanced UV-LED spectrometer. 1σ detection limits of 0.3 ppbv for HONO and 1 ppbv for NO2 were achieved with an optimum acquisition time of 120 s. The measured HONO and NO2 concentrations were compared with the data from commercial HONO (LOPAP) and NO2 (NOX-analyzer) measurement instrument. Typical diurnal pattern of HONO have been observed and the potential formation sources have been analyzed [2]. Acknowledgements The supported by National Natural Science Foundation of China (No. 41265011), Educational Commission of Jiangxi Province of China (No.GJJ14548) and Environment and Conservation Fund of the Hong Kong Special Administrative Region (No. 7/2009). The support of the IRENI program of the Région Nord-Pas de Calaisn, is acknowledged. References [1] W. Chen, R. Maamary, X. Cui, T. Wu, E. Fertein, D. Dewaele, F. Cazier, Q. Zha, Z. Xu, T. Wang, Y. Wang, W. Zhang, X. Gao, W. Liu, F. Dong, 'Photonic Sensing of Environmental Gaseous Nitrous Acid (HONO): Opportunities and Challenges' in The Wonder of Nanotechnology: Quantum Optoelectronic Devices and Applications, M. Razeghi. L. Esaki, and K. von Klitzing, Eds., SPIE Press, Bellingham, WA, 2013, pp. 693-737 [2] T. Wu, Q. Zha, W. Chen, Z. XU, T. Wang, X. He, 'Development and deployment of a cavity enhanced UV

  5. Percutaneous absorption of ketoprofen. I. In vitro release and percutaneous absorption of ketoprofen from different ointment bases.

    PubMed

    Gürol, Z; Hekimoğlu, S; Demirdamar, R; Sumnu, M

    1996-08-01

    Ketoprofen (KP) is a potent non-steroidal anti-inflammatory drug which is used for the treatment of rheumatoid arthritis. The oral administration of KP can cause gastric irritation and renal adverse effects. Topical application of the drug can bypass gastrointestinal disturbances and provide relatively consistent drug levels at the site of action. Since the efficacy of an ointment depends on the type of ointment base and the concentration of the drug, four different bases (white petrolatum, cold cream, hydrophilic ointment and Carbopol 940 gel) were used at 1, 3, 5, 7 and 10% concentrations of KP to evaluate the effect of ointment base and concentration. The general rank order of the drug release was found to be: Carbopol gel > hydrophilic ointment > cold cream > white petrolatum. There was a positive correlation between the concentration of KP and release rate for all bases except Carbopol gel. The in vivo percutaneous absorption of KP from different ointment bases at 3% concentration was studied by carrageenan-induced paw edema in mice. The rank order of the percent edema inhibition was as follows: Carbopol gel > or = hydrophilic ointment > cold cream > white petrolatum. There was a good correlation between the in vitro and in vivo results.

  6. 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.

  7. A high-throughput neutron spectrometer

    NASA Astrophysics Data System (ADS)

    Stampfl, Anton; Noakes, Terry; Bartsch, Friedl; Bertinshaw, Joel; Veliscek-Carolan, Jessica; Nateghi, Ebrahim; Raeside, Tyler; Yethiraj, Mohana; Danilkin, Sergey; Kearley, Gordon

    2010-03-01

    A cross-disciplinary high-throughput neutron spectrometer is currently under construction at OPAL, ANSTO's open pool light-water research reactor. The spectrometer is based on the design of a Be-filter spectrometer (FANS) that is operating at the National Institute of Standards research reactor in the USA. The ANSTO filter-spectrometer will be switched in and out with another neutron spectrometer, the triple-axis spectrometer, Taipan. Thus two distinct types of neutron spectrometers will be accessible: one specialised to perform phonon dispersion analysis and the other, the filter-spectrometer, designed specifically to measure vibrational density of states. A summary of the design will be given along with a detailed ray-tracing analysis. Some preliminary results will be presented from the spectrometer.

  8. Optical Path Switching Based Differential Absorption Radiometry for Substance Detection

    NASA Technical Reports Server (NTRS)

    Sachse, Glen W. (Inventor)

    2000-01-01

    A system and method are provided for detecting one or more substances. An optical path switch divides sample path radiation into a time series of alternating first polarized components and second polarized components. The first polarized components are transmitted along a first optical path and the second polarized components along a second optical path. A first gasless optical filter train filters the first polarized components to isolate at least a first wavelength band thereby generating first filtered radiation. A second gasless optical filter train filters the second polarized components to isolate at least a second wavelength band thereby generating second filtered radiation. The first wavelength band and second wavelength band are unique. Further, spectral absorption of a substance of interest is different at the first wavelength band as compared to the second wavelength band. A beam combiner combines the first and second filtered radiation to form a combined beam of radiation. A detector is disposed to monitor magnitude of at least a portion of the combined beam alternately at the first wavelength band and the second wavelength band as an indication of the concentration of the substance in the sample path.

  9. Millisecond Photoinduced Absorption Studies of Pyridine-Based Copolymer Films

    NASA Astrophysics Data System (ADS)

    Coplin, K. A.; Clark, D. T.; Jessen, S. W.; Epstein, A. J.; Fu, D.-K.; Swager, T. M.

    1997-03-01

    We present a study of the photoexcited states in copolymers of poly(p-pyridyl vinylene) and poly(p-phenylene vinylene) (PPyVPR_iV) with sidegroups R_1=C_12H_25 or R_2=COOC_12H_25 attached at the 2 and 5 positions of the phenyl ring. Previous studies discussed the millisecond photoinduced absorption (ms PA) characteristics of PPyVPR_iV powders(S.W. Jessen et al.), Synth. Met., in press.. In particular, triplet-triplet (T-T) transitions were observed at 1.6 eV for both materials. Additional polaron signatures were also observed in both the electronic ( ~ 0.85 eV) and infrared (1100 - 1600 cm-1) regions of the photoinduced spectrum. We compare these powder results with ms PA features for film morphologies of both the copolymers. We observe a weaker ( ~ 10X) T-T^* transition for copolymer films cast from xylene solution indicating a reduction in triplet exciton production as compared to powder samples. These results are contrasted with the behavior we reported(S.W. Jessen et al.), to be published. earlier for film and powder samples of the parent polymer poly(p-pyridyl vinylene).

  10. A diamond based neutron spectrometer for diagnostics of deuterium-tritium fusion plasmas

    SciTech Connect

    Cazzaniga, C. Nocente, M.; Gorini, G.; Rebai, M.; Giacomelli, L.; Tardocchi, M.; Croci, G.; Grosso, G.; Calvani, P.; Girolami, M.; Trucchi, D. M.; Griesmayer, E.; Pillon, M.

    2014-11-15

    Single crystal Diamond Detectors (SDD) are being increasingly exploited for neutron diagnostics in high power fusion devices, given their significant radiation hardness and high energy resolution capabilities. The geometrical efficiency of SDDs is limited by the size of commercially available crystals, which is often smaller than the dimension of neutron beams along collimated lines of sight in tokamak devices. In this work, we present the design and fabrication of a 14 MeV neutron spectrometer consisting of 12 diamond pixels arranged in a matrix, so to achieve an improved geometrical efficiency. Each pixel is equipped with an independent high voltage supply and read-out electronics optimized to combine high energy resolution and fast signals (<30 ns), which are essential to enable high counting rate (>1 MHz) spectroscopy. The response function of a prototype SDD to 14 MeV neutrons has been measured at the Frascati Neutron Generator by observation of the 8.3 MeV peak from the {sup 12}C(n, α){sup 9}Be reaction occurring between neutrons and {sup 12}C nuclei in the detector. The measured energy resolution (2.5% FWHM) meets the requirements for neutron spectroscopy applications in deuterium-tritium plasmas.

  11. A diamond based neutron spectrometer for diagnostics of deuterium-tritium fusion plasmas.

    PubMed

    Cazzaniga, C; Nocente, M; Rebai, M; Tardocchi, M; Calvani, P; Croci, G; Giacomelli, L; Girolami, M; Griesmayer, E; Grosso, G; Pillon, M; Trucchi, D M; Gorini, G

    2014-11-01

    Single crystal Diamond Detectors (SDD) are being increasingly exploited for neutron diagnostics in high power fusion devices, given their significant radiation hardness and high energy resolution capabilities. The geometrical efficiency of SDDs is limited by the size of commercially available crystals, which is often smaller than the dimension of neutron beams along collimated lines of sight in tokamak devices. In this work, we present the design and fabrication of a 14 MeV neutron spectrometer consisting of 12 diamond pixels arranged in a matrix, so to achieve an improved geometrical efficiency. Each pixel is equipped with an independent high voltage supply and read-out electronics optimized to combine high energy resolution and fast signals (<30 ns), which are essential to enable high counting rate (>1 MHz) spectroscopy. The response function of a prototype SDD to 14 MeV neutrons has been measured at the Frascati Neutron Generator by observation of the 8.3 MeV peak from the (12)C(n, α)(9)Be reaction occurring between neutrons and (12)C nuclei in the detector. The measured energy resolution (2.5% FWHM) meets the requirements for neutron spectroscopy applications in deuterium-tritium plasmas.

  12. Spectral Calibration Requirement for Earth-Looking Imaging Spectrometers in the Solar Reflected Spectrum

    NASA Technical Reports Server (NTRS)

    Green, R. O.

    1996-01-01

    Earth-looking imaging spectrometers operating in the solar reflected spectrum, measure spectra of the total upwelling radiance for each spatial element in an image. These measurements are used to derive physical parameters of the Earth's surface and atmosphere based on the energy, molecular absorption, and constituent scattering characteristics expressed in the spectra over the region of the image.

  13. 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.

  14. Modification of oral absorption of oxyresveratrol using lipid based nanoparticles.

    PubMed

    Sangsen, Yaowaporn; Wiwattanawongsa, Kamonthip; Likhitwitayawuid, Kittisak; Sritularak, Boonchoo; Wiwattanapatapee, Ruedeekorn

    2015-07-01

    The aim of this study was to develop and assess nanostructured lipid carriers (NLC) compared to solid lipid nanoparticles (SLN) for improving the oral bioavailability of oxyresveratrol (OXY). The OXY formulated as SLN (OXY-SLN) and NLC (OXY-NLC) were prepared by a high shear homogenization technique. The optimized OXY-NLC (NLC3) produced smaller nanoparticle sizes (96±0.9nm) than that of the OXY-SLN (108±0.3nm) with a homogeneous size distribution and a high zeta potential. The spherical NLC had a significantly higher efficiency for OXY entrapment (89±0.1%) and a better stability than the SLN after storage for 12 months at 4±2°C according to parameters such as smaller particles, greater zeta potential and a higher loading capacity (p<0.05). Differential scanning calorimetry (DSC) showed a less ordered crystalline structure of NLC than SLN. The accumulated drug in an amorphous state in the NLC was also confirmed by powder X-ray diffraction (PXRD). The in vitro release profiles of the OXY-NLC showed a more sustained release compared to the SLN and unformulated OXY. The in vivo pharmacokinetic profiles implied enterohepatic recycling of OXY in the Wistar rat. Meanwhile, the oral absorption pattern of OXY was modified by both types of lipid nanoparticles. The SLN and NLC increased the relative bioavailability of OXY to 125% and 177%, respectively, compared with unformulated OXY. These findings indicated that NLC could be used as a potential carrier to improve the oral bioavailability of OXY.

  15. A polar cap absorption model optimization based on the vertical ionograms analysis

    NASA Astrophysics Data System (ADS)

    Zaalov, N. Y.; Moskaleva, E. V.

    2016-11-01

    Space weather events significantly affect the high frequency (HF) radio wave propagation. The now-casting and forecasting of HF radio wave absorption is important for the HF communication industries. This paper assimilates vertical sounding data into an absorption model to improve its performance as a now-casting tool. The approach is a modification of the algorithm elaborated by Sauer and Wilkinson, which is based on the riometer data. The optimization is focused on accounting for short timescale variation of the absorption. It should be noted that the expression of the frequency dependence of absorption induced by the energetic particle precipitation employed in Sauer and Wilkinson model is based on the riometer data at frequencies of 20, 30, and 50 MHz. The approach suggested in this paper provides an opportunity for expanding the frequency dependence of the absorption for frequencies below 10 MHz. The simulation of the vertical ionograms in the polar cap region uses a computational model designed to overcome the high frequency wave propagation problem in high latitude of the Earth. HF radio wave absorption induced by solar UV illumination, X-ray flares and energetic particles precipitation is taken into consideration in our model. The absorption caused by the energetic particle precipitation is emphasized, because the study is focused on HF wave propagation in polar cap region. A comparison of observed and simulated vertical ionograms enables the coefficients, which relate absorption (day-time and night-time) to integral proton flux to be refined. The values of these coefficients determined from evaluation of the data recorded by any reliable ionosonde are valid for absorption calculation in high-latitude region.

  16. Measurements of ozone columns in different atmospheric layers over St. Petersburg (Russia) using ground-based FTIR spectrometer in comparison with IASI satellite data

    NASA Astrophysics Data System (ADS)

    Virolainen, Yana; Eremenko, Maxim; Timofeyev, Yury; Dufour, Gaelle; Poberovsky, Anatoly; Polyakov, Alexander; Imhasin, Hamud

    2014-05-01

    Ozone plays a key role in the photochemical equilibrium of the atmosphere. In the stratosphere, it absorbs harmful ultraviolet solar radiation, in the troposphere it is one of the main air pollutant, greenhouse gases and it is involved in the troposphere's oxidative capacity. In this study, we analyze the ozone variability in different atmospheric layers over St. Petersburg (Russia) measured with the ground-based FTIR spectrometer Bruker 125 HR at the Peterhof station (59.82 N, 29.88 E), and compare it to the satellite Infrared Atmospheric Sounding Interferometer (IASI) ozone retrievals. The FTIR spectrometer has a maximum optical path difference of 180 cm, yielding an apodized spectral resolution of 0.008 cm-1, and has been recording IR spectra since 2009. The high spectral resolution of the registered spectra allows the retrieval of the ozone content in four atmospheric layers. We applied the PROFFIT inversion code to the ozone vertical profiles retrievals in 9.6-µm O3 absorption band and calculated the daily means of ozone partial columns for about 300 days between 2009 and 2013. The IASI instrument onboard the satellite MetOp-A measures the thermal infrared radiation emitted by the Earth's surface and the atmosphere with an apodized spectral resolution of 0.5 cm-1. We used the LISA (Laboratoire Inter-universitaire des Systemes Atmospheriques) retrieval algorithm for deriving the ozone profiles between 0 and 60 km for the region of 2 degrees around the Peterhof station in coincidence with FTIR-observation dates, and averaged profiles daily over all the pixels in the considered region. In this study, we compare and discuss the both types of ozone retrievals: total and partial columns in four atmospheric layers (0-12 km, 12-18 km, 18-25 km, and 25-60 km) for 285 coincident days in 2009-2013. This study was partly supported by Saint-Petersburg State University (project No. 11.0.44.2010) and Russian Foundation for Basic Research (grants No. 12-05-00596, 12

  17. Methane cross-validation between three Fourier transform spectrometers: SCISAT ACE-FTS, GOSAT TANSO-FTS, and ground-based FTS measurements in the Canadian high Arctic

    NASA Astrophysics Data System (ADS)

    Holl, Gerrit; Walker, Kaley A.; Conway, Stephanie; Saitoh, Naoko; Boone, Chris D.; Strong, Kimberly; Drummond, James R.

    2016-05-01

    We present cross-validation of remote sensing measurements of methane profiles in the Canadian high Arctic. Accurate and precise measurements of methane are essential to understand quantitatively its role in the climate system and in global change. Here, we show a cross-validation between three data sets: two from spaceborne instruments and one from a ground-based instrument. All are Fourier transform spectrometers (FTSs). We consider the Canadian SCISAT Atmospheric Chemistry Experiment (ACE)-FTS, a solar occultation infrared spectrometer operating since 2004, and the thermal infrared band of the Japanese Greenhouse Gases Observing Satellite (GOSAT) Thermal And Near infrared Sensor for carbon Observation (TANSO)-FTS, a nadir/off-nadir scanning FTS instrument operating at solar and terrestrial infrared wavelengths, since 2009. The ground-based instrument is a Bruker 125HR Fourier transform infrared (FTIR) spectrometer, measuring mid-infrared solar absorption spectra at the Polar Environment Atmospheric Research Laboratory (PEARL) Ridge Laboratory at Eureka, Nunavut (80° N, 86° W) since 2006. For each pair of instruments, measurements are collocated within 500 km and 24 h. An additional collocation criterion based on potential vorticity values was found not to significantly affect differences between measurements. Profiles are regridded to a common vertical grid for each comparison set. To account for differing vertical resolutions, ACE-FTS measurements are smoothed to the resolution of either PEARL-FTS or TANSO-FTS, and PEARL-FTS measurements are smoothed to the TANSO-FTS resolution. Differences for each pair are examined in terms of profile and partial columns. During the period considered, the number of collocations for each pair is large enough to obtain a good sample size (from several hundred to tens of thousands depending on pair and configuration). Considering full profiles, the degrees of freedom for signal (DOFS) are between 0.2 and 0.7 for TANSO-FTS and

  18. Methane cross-validation between three Fourier Transform Spectrometers: SCISAT ACE-FTS, GOSAT TANSO-FTS, and ground-based FTS measurements in the Canadian high Arctic

    NASA Astrophysics Data System (ADS)

    Holl, G.; Walker, K. A.; Conway, S.; Saitoh, N.; Boone, C. D.; Strong, K.; Drummond, J. R.

    2015-12-01

    We present cross-validation of remote sensing measurements of methane profiles in the Canadian high Arctic. Accurate and precise measurements of methane are essential to understand quantitatively its role in the climate system and in global change. Here, we show a cross-validation between three datasets: two from spaceborne instruments and one from a ground-based instrument. All are Fourier Transform Spectrometers (FTSs). We consider the Canadian SCISAT Atmospheric Chemistry Experiment (ACE)-FTS, a solar occultation infrared spectrometer operating since 2004, and the thermal infrared band of the Japanese Greenhouse Gases Observing Satellite (GOSAT) Thermal And Near infrared Sensor for carbon Observation (TANSO)-FTS, a nadir/off-nadir scanning FTS instrument operating at solar and terrestrial infrared wavelengths, since 2009. The ground-based instrument is a Bruker 125HR Fourier Transform Infrared (FTIR) spectrometer, measuring mid-infrared solar absorption spectra at the Polar Environment Atmospheric Research Laboratory (PEARL) Ridge Lab at Eureka, Nunavut (80° N, 86° W) since 2006. For each pair of instruments, measurements are collocated within 500 km and 24 h. An additional criterion based on potential vorticity values was found not to significantly affect differences between measurements. Profiles are regridded to a common vertical grid for each comparison set. To account for differing vertical resolutions, ACE-FTS measurements are smoothed to the resolution of either PEARL-FTS or TANSO-FTS, and PEARL-FTS measurements are smoothed to the TANSO-FTS resolution. Differences for each pair are examined in terms of profile and partial columns. During the period considered, the number of collocations for each pair is large enough to obtain a good sample size (from several hundred to tens of thousands depending on pair and configuration). Considering full profiles, the degrees of freedom for signal (DOFS) are between 0.2 and 0.7 for TANSO-FTS and between 1.5 and 3

  19. [Extracting THz absorption coefficient spectrum based on accurate determination of sample thickness].

    PubMed

    Li, Zhi; Zhang, Zhao-hui; Zhao, Xiao-yan; Su, Hai-xia; Yan, Fang

    2012-04-01

    Extracting absorption spectrum in THz band is one of the important aspects in THz applications. Sample's absorption coefficient has a complex nonlinear relationship with its thickness. However, as it is not convenient to measure the thickness directly, absorption spectrum is usually determined incorrectly. Based on the method proposed by Duvillaret which was used to precisely determine the thickness of LiNbO3, the approach to measuring the absorption coefficient spectra of glutamine and histidine in frequency range from 0.3 to 2.6 THz(1 THz = 10(12) Hz) was improved in this paper. In order to validate the correctness of this absorption spectrum, we designed a series of experiments to compare the linearity of absorption coefficient belonging to one kind amino acid in different concentrations. The results indicate that as agreed by Lambert-Beer's Law, absorption coefficient spectrum of amino acid from the improved algorithm performs better linearity with its concentration than that from the common algorithm, which can be the basis of quantitative analysis in further researches.

  20. One shot confocal microscopy based on wavelength/space conversion by use of multichannel spectrometer

    NASA Astrophysics Data System (ADS)

    Miyamoto, Shuji; Hase, Eiji; Ichikawa, Ryuji; Mnamikawa, Takeo; Yasui, Takeshi; Yamamoto, Hirotugu

    2016-03-01

    Confocal laser microscope (CLM) has been widely used in the fields of the non-contact surface topography, biomedical imaging, and other applications, because of two-dimensional (2D) or three-dimensional (3D) imaging capability with the confocal effect and the stray light elimination. Although the conventional CLM has acquired the 2D image by mechanical scanning of the focused beam spot, further reduction of image acquisition time and the robustness to various disturbances are strongly required. To this end, it is essential to omit mechanical scanning for the image acquisition. In this article, we developed the scan-less, full-field CLM by combination of the line-focused CLM with the wavelength/1D-space conversion. This combination enables us to form the 2D focal array of a 2D rainbow beam on a sample and to encode the 2D image information of a sample on the 2D rainbow beam. The image-encoded 2D rainbow beam was decoded as a spectral line image by a multi-channel spectrometer equipped with a CMOS camera without the need for the mechanical scanning. The confocal full-field image was acquired during 0.23 ms with the lateral resolution of 26.3μm and 4.9μm for the horizontal and vertical directions, respectively, and the depth resolution of 34.9μm. We further applied this scan-less, full-field CLM for biomedical imaging of a sliced specimen and non-contact surface topography of an industry products. These demonstrations highlight a high potential of the proposed scan-less, full-field CLM.

  1. Multiple myeloma detection based on blood plasma surface-enhanced Raman spectroscopy using a portable Raman spectrometer

    NASA Astrophysics Data System (ADS)

    Chen, Jie; Huang, Meizhen; Zou, Ye; Song, Biao; Wang, Yang; Wang, Kehui; Li, Xia; Liu, Xi; Chen, Xiaofan; Li, Feng; Zhan, Yanxia

    2016-10-01

    The feasibility of surface enhanced Raman spectroscopy (SERS) for multiple myeloma (MM) detection is investigated in this work. SERS measurements of silver nanoparticle mixed blood plasma samples are performed using a low-cost and portable Raman spectrometer. The tentative assignment of Raman peaks indicates an increase in amino acids, nucleic acid base content and a decrease in cholesterol ester in the MM group. Combined with the multivariate analysis method of principle component analysis (PCA) and linear discriminate analysis (LDA), a diagnosis result for 32 samples with a sensitivity of 93.75% and specificity of 87.5% is achieved. The performance of the corresponding receiver operating characteristic (ROC) curve is 0.957. It is a potential rapid and non-invasive method for preliminary MM screening.

  2. Modeling and simulation of blazed grating based on MEMS scanning micro-mirror for NIR micro-spectrometer

    NASA Astrophysics Data System (ADS)

    Zhou, Ying; Wen, Zhiyu; Yang, Tingyan; Lei, Hongjie

    2015-11-01

    Near infrared micro-spectrometer (NIRMS) as a vital detection equipment for various elements has been investigated over the last few years. Traditional MEMS NIRMS employs CCD array detectors for NIR spectrum collection and this leads to higher fabrication cost. In this paper, to ensure the higher diffraction efficiency as well as lower fabrication cost, a novel blazed grating based on MEMS scanning micro-mirror (SMM) is proposed. By our design method, the NIRMS needs only one single InGaAs detector photo diode to collect NIR spectrum and ensure the high diffraction efficiency. Our results show that the diffraction efficiency of the blazed grating is almost 50% and the peak value reaches to 90% in the range of 900-2,100 nm while the optical scanning angle is 14.2°.

  3. Design of a variable-line-spacing grating pattern for spectrometers based on a grating Fresnel device.

    PubMed

    Li, Xinghui; Zhang, Jinchao; Zhou, Qian; Ni, Kai; Pang, Jinchao; Tian, Rui

    2016-04-01

    In this Letter, we propose a variable-line-spacing (VLS) grating pattern for a hybrid diffractive device termed a grating Fresnel (G-Fresnel) lens, which is used in spectrometers to improve spectral resolution over a wide spectral range. The VLS grating pattern disperses light of specific wavelengths with a different angle and position such that the aberration caused by the Fresnel surface can be compensated for. In this manner, high resolution can be achieved over a relatively wide spectral range. The VLS grating pattern is designed based on the least wave-change principle and simulated by ZEMAX. Results reveal that the VLS G-Fresnel device allows a subnanometer resolution over a spectral range of 200 nm.

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

    NASA Astrophysics Data System (ADS)

    Chuang, Yi-De; Shao, Yu-Cheng; Cruz, Alejandro; Hanzel, Kelly; Brown, Adam; Frano, Alex; Qiao, Ruimin; Smith, Brian; Domning, Edward; Huang, Shih-Wen; Wray, L. Andrew; Lee, Wei-Sheng; Shen, Zhi-Xun; Devereaux, Thomas P.; Chiou, Jaw-Wern; Pong, Way-Faung; Yashchuk, Valeriy V.; Gullikson, Eric; Reininger, Ruben; Yang, Wanli; Guo, Jinghua; Duarte, Robert; Hussain, Zahid

    2017-01-01

    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 source (˜1 μ m) and detector pixels (˜5 μ m) 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 LiNi1/3Co1/3Mn1/3O2 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. We propose that this modular spectrometer design can serve as the platform for further customization to meet specific scientific demands.

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

    PubMed

    Chuang, Yi-De; Shao, Yu-Cheng; Cruz, Alejandro; Hanzel, Kelly; Brown, Adam; Frano, Alex; Qiao, Ruimin; Smith, Brian; Domning, Edward; Huang, Shih-Wen; Wray, L Andrew; Lee, Wei-Sheng; Shen, Zhi-Xun; Devereaux, Thomas P; Chiou, Jaw-Wern; Pong, Way-Faung; Yashchuk, Valeriy V; Gullikson, Eric; Reininger, Ruben; Yang, Wanli; Guo, Jinghua; Duarte, Robert; Hussain, Zahid

    2017-01-01

    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 source (∼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 LiNi1/3Co1/3Mn1/3O2 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. We propose that this modular spectrometer design can serve as the platform for further customization to meet specific scientific demands.

  6. CMOS-compatible silicon nitride spectrometers for lab-on-a-chip spectral sensing

    NASA Astrophysics Data System (ADS)

    Ryckeboer, Eva; Nie, Xiaomin; Subramanian, Ananth Z.; Martens, Daan; Bienstman, Peter; Clemmen, Stephane; Severi, Simone; Jansen, Roelof; Roelkens, Gunther; Baets, Roel

    2016-05-01

    We report on miniaturized optical spectrometers integrated on a photonic integrated circuit (PIC) platform based on silicon nitride waveguides and fabricated in a CMOS-compatible approach. As compared to a silicon- on-insulator PIC-platform, the usage of silicon nitride allows for operation in the visible and near infrared. Furthermore, the moderately high refractive index contrast in silicon-nitride photonic wire waveguides provides a valuable compromise between compactness, optical loss and sensitivity to phase error. Three generic types of on-chip spectrometers are discussed: the arrayed waveguide grating (AWG) spectrometer, the echelle grating or planar concave grating (PCG) spectrometer and the stationary Fourier transform spectrometer (FTS) spectrometer. Both the design as well as experimental results are presented and discussed. For the FTS spectrometer a specific design is described in detail leading to an ultra-small (0.1 mm2) footprint device with a resolution of 1 nm and a spectral range of 100nm. Examples are given of the usage of these spectrometers in refractive index biosensing, absorption spectroscopy and Raman spectroscopy.

  7. [Gas Concentration Measurement Based on the Integral Value of Absorptance Spectrum].

    PubMed

    Liu, Hui-jun; Tao, Shao-hua; Yang, Bing-chu; Deng, Hong-gui

    2015-12-01

    The absorptance spectrum of a gas is the basis for the qualitative and quantitative analysis of the gas by the law of the Lambert-Beer. The integral value of the absorptance spectrum is an important parameter to describe the characteristics of the gas absorption. Based on the measured absorptance spectrum of a gas, we collected the required data from the database of HIT-RAN, and chose one of the spectral lines and calculated the integral value of the absorptance spectrum in the frequency domain, and then substituted the integral value into Lambert-Beer's law to obtain the concentration of the detected gas. By calculating the integral value of the absorptance spectrum we can avoid the more complicated calculation of the spectral line function and a series of standard gases for calibration, so the gas concentration measurement will be simpler and faster. We studied the changing trends of the integral values of the absorptance spectrums versus temperature. Since temperature variation would cause the corresponding variation in pressure, we studied the changing trends of the integral values of the absorptance spectrums versus both the pressure not changed with temperature and changed with the temperature variation. Based on the two cases, we found that the integral values of the absorptance spectrums both would firstly increase, then decrease, and finally stabilize with temperature increasing, but the ranges of specific changing trend were different in the two cases. In the experiments, we found that the relative errors of the integrated values of the absorptance spectrum were much higher than 1% and still increased with temperature when we only considered the change of temperature and completely ignored the pressure affected by the temperature variation, and the relative errors of the integrated values of the absorptance spectrum were almost constant at about only 1% when we considered that the pressure were affected by the temperature variation. As the integral value

  8. Optical-Fiber-Based, Time-Resolved Photoluminescence Spectrometer for Thin-Film Absorber Characterization and Analysis of TRPL Data for CdS/CdTe Interface: Preprint

    SciTech Connect

    Kuciauskas, D.; Duenow, J. N.; Kanevce, A.; Li, J. V.; Young, M. R.; Dippo, P.; Levi, D. H.

    2012-06-01

    We describe the design of a time resolved photoluminescence (TRPL) spectrometer for rapid semiconductor absorber characterization. Simplicity and flexibility is achieved by using single optical fiber to deliver laser pulses and to collect photoluminescence. We apply TRPL for characterization of CdS/CdTe absorbers after deposition, CdCl2 treatment, Cu doping, and back contact formation. Data suggest this method could be applied in various stages of PV device processing. Finally, we show how to analyze TRPL data for CdS/CdTe absorbers by considering laser light absorption depth and intermixing at CdS/CdTe interface.

  9. Transient Supersaturation Supports Drug Absorption from Lipid-Based Formulations for Short Periods of Time, but Ongoing Solubilization Is Required for Longer Absorption Periods.

    PubMed

    Crum, Matthew F; Trevaskis, Natalie L; Pouton, Colin W; Porter, Christopher J H

    2017-02-06

    The current studies sought to explore the impact of drug supersaturation and precipitation during the dispersion and digestion of lipid-based formulations (LBFs), on in vivo absorption using a coupled in vitro digestion-in vivo perfusion absorption model. Fenofibrate absorption was evaluated from a number of LBFs with different solubilization and supersaturation capacities, and conditions at the absorptive membrane manipulated by changing perfusion conditions, intestine segment lengths, and by the conduct of experiments in the presence or absence of suspended/precipitated drug. LBF dispersion and digestion resulted in varying periods of supersaturation across the different formulations. Even fleeting (5-10 min) periods of supersaturation were able to drive flux across a perfused 10 cm intestinal segment for up to 60 min, although over longer infusion periods (60-80 min) flux dropped in the absence of ongoing drug solubilization and supersaturation. In contrast, the presence or absence of precipitated/suspended drug, had little impact on drug flux. When perfused intestinal segment lengths were extended, the role of initial supersaturation was attenuated and ongoing solubilization conditions became the primary driver of absorptive flux. The data suggest that for highly permeable drugs such as fenofibrate, a short period of supersaturation at the absorptive membrane may be sufficient to drive absorptive drug flux in spite of significant drug precipitation on formulation dispersion or digestion in vitro. In contrast, where longer periods of absorption are required, for example, at higher doses, the requirement for ongoing solubilization and supersaturation becomes more apparent.

  10. Airborne measurements of CO2 and CH4 onboard the UK FAAM research aircraft using a, Los Gatos Research Inc, cavity enhanced absorption spectrometer

    NASA Astrophysics Data System (ADS)

    O'Shea, S.; Bauguitte, S.; Muller, J. B.; Le Breton, M.; Gallagher, M. W.; Allen, G.; Percival, C. J.

    2012-12-01

    Airborne measurements of CO2 and CH4 have been made using the UK Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 research aircraft since spring 2011.The measurement system uses a commercially available analyser, based on the off-axis integrated cavity output spectroscopy technique, from Los Gatos Research Inc (FGGA, Model RMT-200). During the first year of operation (29 flights), 1 Hz measurements were found to be accurate to 0.07 ± 2.48ppbv for CH4 and -0.06± 0.66ppmv for CO2. In summer 2011, as part of the BORTAS project (Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites), outflow from boreal forest fires was measured in Eastern Canada. A number of fresh and photochemically-aged plumes were identified using simultaneous HCN measurements, a widely used tracer for biomass burning. In the freshest plumes, strong relationships were found between CH4, CO2 and other tracers for biomass burning. From this we were able to estimate that 6.9±0.8 g of CH4 and 1551±213 g of CO2 were released into the atmosphere per kg of dry matter burnt. These emission factors are in good agreement with estimates from previous studies in boreal regions. However for aged plumes the correlations between CH4 and other biomass burning tracers were not as robust, most likely due to mixing from other CH4 emission sources, such as the wetland regions. The role of additional emission sources will be investigated using the UK Met Office NAME atmospheric dispersion model and the HYSPLIT trajectory model. Using tailored back trajectory analysis, we will present an interpretation of this new dataset in the context of air mass/fire origin, relating this to MODIS fire maps and source strength.

  11. Analyses of cosmic ray induced-neutron based on spectrometers operated simultaneously at mid-latitude and Antarctica high-altitude stations during quiet solar activity

    NASA Astrophysics Data System (ADS)

    Hubert, G.

    2016-10-01

    In this paper are described a new neutron spectrometer which operate in the Concordia station (Antarctica, Dome C) since December 2015. This instrument complements a network including neutron spectrometers operating in the Pic-du-Midi and the Pico dos Dias. Thus, this work present an analysis of cosmic ray induced-neutron based on spectrometers operated simultaneously in the Pic-du-Midi and the Concordia stations during a quiet solar activity. The both high station platforms allow for investigating the long period dynamics to analyze the spectral variation and effects of local and seasonal changes, but also the short term dynamics during solar flare events. A first part is devoted to analyze the count rates, the spectrum and the neutron fluxes, implying cross-comparisons between data obtained in the both stations. In a second part, measurements analyses were reinforced by modeling based on simulations of atmospheric cascades according to primary spectra which only depend on the solar modulation potential.

  12. Expert system-based mineral mapping in northern Death Valley, California/Nevada, using the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS)

    NASA Technical Reports Server (NTRS)

    Kruse, F. A.; Lefkoff, A. B.; Dietz, J. B.

    1993-01-01

    Integrated analysis of imaging spectrometer data and field spectral measurements were used in conjunction with conventional geologic field mapping to characterize bedrock and surficial geology at the northern end of Death Valley, California and Nevada. A knowledge-based expert system was used to automatically produce image maps showing the principal surface mineralogy from Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data. Linear spectral unmixing of the AVIRIS data allowed further determination of relative mineral, abundances and identification of mineral assemblages and mixtures. The imaging spectrometer data show the spatial distribution of spectrally distinct minerals occurring both as primary rockforming minerals and as alteration and weathering products. Field spectral measurements were used to verify the mineral maps and field mapping was used to extend the remote sensing results. Geographically referenced image maps produced from these data form new base maps from which to develop improved understanding of the processes of deposition and erosion affecting the present land surface.

  13. Total Columns and Vertical Profiles of Carbon Monoxide Measured Over Toronto Using a Ground-Based Fourier Transform InfraRed (FTIR) Spectrometer: Comparisons With Measurements of Pollution in the Troposphere (MOPITT) Data (Jan 2002 - Sep 2003)

    NASA Astrophysics Data System (ADS)

    Wiacek, A.; Taylor, J. R.; Strong, K.; Liu, J.; Bremer, H.; Drummond, J. R.

    2004-05-01

    A high-resolution Fourier Transform InfraRed (FTIR) spectrometer is the primary instrument at the University of Toronto Atmospheric Observatory (TAO), established in 2001. Continuous measurements of solar absorption spectra using narrow band optical filters began in October 2001 for the purpose of building a long-term data set of key species related to climate change and mid-latitude atmospheric chemistry, and for the validation of satellite instruments. Measurements have greater temporal coverage in the summer and fall months due to favourable weather conditions. Total columns and low-resolution vertical profiles of carbon monoxide have been derived from the high-resolution (0.004 cm-1) solar absorption spectra recorded at TAO using lines in the (1-0) transition region near 4.7 μ m. Microwindows were chosen to approximately match Measurements of Pollution in the Troposphere (MOPITT) averaging kernels and spectra were analyzed using the SFIT-2 optimal estimation method retrieval algorithm (developed at NASA Langley Research Centre, USA, and National Institute for Water and Atmospheric Research (NIWA), New Zealand.) Monochromatic transmittances were calculated in the forward model assuming a Voigt line shape and using the HITRAN 2000+ spectral database, NCEP temperature and pressure profiles as well as volume mixing ratio a priori information for CO and interfering species. The averaging kernels of both observation platforms have been considered in the analysis. Comparisons between ground-based solar absorption FTIR and MOPITT total columns and vertical profiles will be presented.

  14. Absorption properties of GaAsBi based p-i-n heterojunction diodes

    NASA Astrophysics Data System (ADS)

    Zhou, Zhize; Mendes, Danuta F.; Richards, Robert D.; Bastiman, Faebian; David, John PR

    2015-09-01

    The absorption properties of GaAsBi have been investigated using GaAsBi based p-i-n diodes with different bismuth compositions (˜2.1 and ˜3.4%). The absorption behaviour of GaAsBi as a function of incident photon energy above the band gap follows that of a direct band gap material. With increasing bismuth content, the absorption of photons with energy lower than the band gap in GaAsBi is enhanced, probably due to localized states caused by Bi-related defects. A simplified analysis has been undertaken on the behaviour of absorption as a function of bias voltage. By undertaking photoresponsivity measurements as a function of reverse bias, the background doping type and the minority carriers diffusion lengths in GaAsBi have been determined.

  15. Tunable THz wave absorption by graphene-assisted plasmonic metasurfaces based on metallic split ring resonators

    NASA Astrophysics Data System (ADS)

    Ahmadivand, Arash; Sinha, Raju; Karabiyik, Mustafa; Vabbina, Phani Kiran; Gerislioglu, Burak; Kaya, Serkan; Pala, Nezih

    2017-01-01

    Graphene plasmonics has been introduced as a novel platform to design various nano- and microstructures to function in a wide range of spectrum from optical to THz frequencies. Herein, we propose a tunable plasmonic metamaterial in the THz regime by using metallic (silver) concentric microscale split ring resonator arrays on a multilayer metasurface composed of silica and silicon layers. We obtained an absorption percentage of 47.9% including two strong Fano resonant dips in THz regime for the purely plasmonic metamaterial without graphene layer. Considering the data of an atomic graphene sheet (with the thickness of 0.35 nm) in both analytical and experimental regimes obtained by prior works, we employed a graphene layer under concentric split ring resonator arrays and above the multilayer metasurface to enhance the absorption ratio in THz bandwidth. Our numerical and analytical results proved that the presence of a thin graphene layer enhances the absorption coefficient of MM to 64.35%, at the highest peak in absorption profile that corresponds to the Fano dip position. We also have shown that changing the intrinsic characteristics of graphene sheet leads to shifts in the position of Fano dips and variations in the absorption efficiency. The maximum percentage of absorption ( 67%) was obtained for graphene-based MM with graphene layer with dissipative loss factor of 1477 Ω. Employing the antisymmetric feature of the split ring resonators, the proposed graphene-based metamaterial with strong polarization dependency is highly sensitive to the polarization angle of the incident THz beam.

  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. Revisiting absorption of dietary plant-based miRNAs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We are continuing to test the hypothesis that consumption of genetic information in plant-based foods can modulate animal metabolism. Several studies (1,2,3) have failed to replicate the finding (4) that a rice miRNA survives digestion, enters circulation in copy numbers rivaling endogenous RNAs, an...

  18. Mars Organic Molecule Analyzer (MOMA) Mass Spectrometer Flight Model and Future Ion Trap-Based Planetary Instruments

    NASA Astrophysics Data System (ADS)

    Brinckerhoff, W. B.; van Amerom, F. H. W.; Danell, R.; Pinnick, V. T.; Arevalo, R. D., Jr.; Li, X.; Grubisic, A.; Getty, S.; Hovmand, L.; Mahaffy, P. R.

    2015-12-01

    The Mars Organic Molecule Analyzer (MOMA) investigation on the 2018 ExoMars rover will examine the chemical composition of samples acquired from depths of up to two meters below the martian surface, where organics may be protected from radiative and oxidative degradation. MOMA combines pyrolysis gas chromatography mass spectrometry (GCMS) of bulk powder samples and Mars ambient laser desorption mass spectrometry (LDMS) surface analysis, using a single ion trap MS. This dual source design enables MOMA to detect compounds over a wide range of molecular weights and volatilities. The structure of any detected organics may be further examined using MOMA's tandem mass spectrometry (MS/MS) mode. The flight model (FM) ion trap sensor and electronics have been assembled under the extremely clean and sterile conditions required by ExoMars, and have met or exceeded all performance specifications during initial functional tests. After Mars ambient thermal cycling and calibration, the FM will be delivered as a subsystem of MOMA to rover integration in mid-2016. There MOMA will join complementary rover instruments such as the Raman and MicrOmega spectrometers designed to analyze common drill samples. Following the MOMA design, linear ion trap mass spectrometer (LITMS)-based instruments are under development for future missions. LITMS adds enhanced capabilities such as precision (point-by-point) analysis of drill cores, negative ion detection, a wider mass range, and higher temperature pyrolysis with precision evolved gas analysis, while remaining highly compact and robust. Each of the capabilities of LITMS has been demonstrated on breadboard hardware. The next phase will realize an end-to-end brassboard at flight scale that will meet stringent technology readiness level (TRL) 6 criteria, indicating readiness for development toward missions to Mars, comets, asteroids, outer solar system moons, and beyond.

  19. Theory and Applications of a Faraday Filter-Based Spectrometer to Measure Sodium Nightglow D2/D1 Intensity Ratios

    NASA Astrophysics Data System (ADS)

    Harrell, S. D.; She, C.; Krueger, D. A.; Yuan, T.; Reising, S. C.

    2008-12-01

    The Chapman mechanism (1939) offers the accepted chemical pathway for the production of excited states of mesospheric sodium, leading to nightglow at two wavelengths: D2 (589.158 nm) and D1 (589.756 nm). While the Chapman mechanism leaves open the possibility that the intensity ratio of the two transitions may vary due to the chemical reaction involving atomic oxygen, early observations by Sipler and Biondi (1978) yielded the value of two within experimental error. Recent work by Slanger et al. (2005), however, showed that not only does the intensity ratio vary, but its value is related to the concentration ratio of atomic oxygen [O] to molecular oxygen [O2]. They proposed a modification of the Chapman mechanism involving two competing chemical pathways for sodium production to account for the observed variation. This paper will describe our compact, Faraday filter-based spectrometer to measure the D2/D1 intensity ratio of the sodium nightglow from the upper mesosphere. The novelty of this method also permits determination of the fractional contributions of the two chemical pathways to test the validity of the modified Chapman mechanism for Na chemistry, as well as to infer information about [O]/[O2]. Since the delineation between the two chemical pathways requires a spectral resolution of 0.0002 nm, this is not possible with any other existing instrument. With this spectrometer deployed at the Colorado State University sodium lidar facility (41°N, 105°W), we expect to be able to measure short-term variations of the sodium nightglow intensity ratio and the chemical pathway fraction, from which [O]/[O2] can be inferred. These observations may yield new insights into mesospheric chemistry, especially for atomic and molecular oxygen, which play a key role in upper atmospheric chemistry and dynamics.

  20. Tracing of recently assimilated carbon in respiration at high temporal resolution in the field with a tuneable diode laser absorption spectrometer after in situ 13CO2 pulse labelling of 20-year-old beech trees.

    PubMed

    Plain, Caroline; Gerant, Dominique; Maillard, Pascale; Dannoura, Masako; Dong, Yanwen; Zeller, Bernd; Priault, Pierrick; Parent, Florian; Epron, Daniel

    2009-11-01

    The study of the fate of assimilated carbon in respiratory fluxes in the field is needed to resolve the residence and transfer times of carbon in the atmosphere-plant-soil system in forest ecosystems, but it requires high frequency measurements of the isotopic composition of evolved CO2. We developed a closed transparent chamber to label the whole crown of a tree and a labelling system capable of delivering a 3-h pulse of 99% 13CO2 in the field. The isotopic compositions of trunk and soil CO2 effluxes were recorded continuously on two labelled and one control trees by a tuneable diode laser absorption spectrometer during a 2-month chase period following the late summer labelling. The lag times for trunk CO2 effluxes are consistent with a phloem sap velocity of about 1 m h(-1). The isotopic composition (delta13C) of CO2 efflux from the trunk was maximal 2-3 days after labelling and declined thereafter following two exponential decays with a half-life of 2-8 days for the first and a half-life of 15-16 days for the second. The isotopic composition of the soil CO2 efflux was maximal 3-4 days after labelling and the decline was also well fitted with a sum of two exponential functions with a half-life of 3-5 days for the first exponential and a half-life of 16-18 days for the second. The amount of label recovered in CO2 efflux was around 10-15% of the assimilated 13CO2 for soil and 5-13% for trunks. As labelling occurred late in the growing season, substantial allocation to storage is expected.

  1. Photonuclear reaction based high-energy x-ray spectrometer to cover from 2 MeV to 20 MeVa)

    NASA Astrophysics Data System (ADS)

    Sakata, S.; Arikawa, Y.; Kojima, S.; Ikenouchi, T.; Nagai, T.; Abe, Y.; Inoue, H.; Morace, A.; Utsugi, M.; Kato, R.; Nishimura, H.; Nakai, M.; Shiraga, H.; Fujioka, S.; Azechi, H.

    2014-11-01

    A photonuclear-reaction-based hard x-ray spectrometer is developed to measure the number and energy spectrum of fast electrons generated by interactions between plasma and intense laser light. In this spectrometer, x-rays are converted to neutrons through photonuclear reactions, and the neutrons are counted with a bubble detector that is insensitive to x-rays. The spectrometer consists of a bundle of hard x-ray detectors that respond to different photon-energy ranges. Proof-of-principle experiment was performed on a linear accelerator facility. A quasi-monoenergetic electron bunch (Ne = 1.0 × 10-6 C, Ee = 16 ± 0.32 MeV) was injected into a 5-mm-thick lead plate. Bremsstrahlung x-rays, which emanate from the lead plate, were measured with the spectrometer. The measured spectral shape and intensity agree fairly well with those computed with a Monte Carlo simulation code. The result shows that high-energy x-rays can be measured absolutely with a photon-counting accuracy of 50%-70% in the energy range from 2 MeV to 20 MeV with a spectral resolution (Δhν/hν) of about 15%. Quantum efficiency of this spectrometer was designed to be 10-7, 10-4, 10-5, respectively, for 2-10, 11-15, and 15-25 MeV of photon energy ranges.

  2. Energy Absorption of Polyurethane-Based Polymer Alloys.

    DTIC Science & Technology

    1986-01-31

    AD-fli64 537 ENERGY BSORPTION OF POLYURETHANE-BASED POLYMER ALLOYS i/i (U) DETROIT UN V MI POLYME INST S ONI ET AL. UNCLASSIFIED U R R-26 -SDR2...Preparation of Samples 1 1. IPN Elastomers 1 2. IPN Foams 2 C. Testing 2 1. Dynamic Mechanical Spectroscopy 2 2. Standing Wave Apparatus (Bruel & 3...conditioned at 250C and 50% relative humidity for at least three days prior to testing. C. Testing 1. Dynamic Mechanical Spectroscopy All dynamic

  3. Microwave absorption properties of double-layer absorber based on carbonyl iron/barium hexaferrite composites

    NASA Astrophysics Data System (ADS)

    Ren, Xiaohu; Fan, Huiqing; Cheng, Yankui

    2016-05-01

    The microwave absorption properties of BaCo0.4Zn1.6Fe16O27 ferrite and carbonyl iron powder with single-layer and double-layer composite absorbers were investigated based on the electromagnetic transmission line theory in the frequency range from 1 to 14 GHz. XRD was used to characterize the structure of prepared absorbing particles. SEM was used to examine the micromorphology of the particles and composites. The complex permittivity and permeability of composites were measured by using a vector network analyzer. The reflection loss of the single-layer and double-layer absorbers with different thicknesses and orders was investigated. The results show that double-layer absorbers have better microwave absorption properties than single-layer absorbers. The microwave absorption properties of the double-layer structure are influenced by the coupling interactions between the matching and absorption layers. As the pure ferrite used as matching layer and the composite of BF-5CI used as absorption, the minimum RL of absorber can achieve to -55.4 dB and the bandwidth of RL <-10 dB ranged from 5.6 to 10.8 GHz when the thicknesses of matching layer and absorption layer were 0.9 and 1.4 mm, respectively.

  4. Tunable absorption in graphene-based hyperbolic metamaterials for mid-infrared range

    NASA Astrophysics Data System (ADS)

    Ning, Renxia; Liu, Shaobin; Zhang, Haifeng; Bian, Borui; Kong, Xiangkun

    2015-01-01

    Tunable absorption in periodic structure composed of graphene-based hyperbolic metamaterials (GHMMs) and isotropic medium is investigated by the transfer matrix method. The parallel part for relative permittivity of GHMMs consisting of monolayer graphene and conventional dielectric can be tuned by the chemical potential and dielectric layer thickness. The real part of the group index of GHMMs is insensitive to incident angle at the required frequency and the absorption of the periodic structure with GHMMs can be obtained nearly 100% at 22.4 terahertz (THz). The absorption peak of this frequency is almost uniform for both transverse electric (TE) and transverse magnetic (TE) polarizations. However, a new absorption peak can be observed incident angle is larger than 40 degree for TM polarization from 10 to 30 THz. The research results show that the absorption is insensitive to electromagnetic polarization at certain frequency. A new absorption peak can be found with TM polarization in low frequency region. These novel and effective GHMMs can replace metallic thin films as polarizing beam splitter for future optoelectronic applications.

  5. [Study of cholesterol concentration based on serum UV-visible absorption spectrum].

    PubMed

    Zhu, Wei-Hua; Zhao, Zhi-Min; Guo, Xin; Chen, Hui

    2009-04-01

    In the present paper, UV-visible absorption spectrum and neural network theory were used for the analysis of cholesterol concentration. Experimental investigation shows that the absorption spectrum has the following characteristics in the wave band of 350-600 nm: (1) There is a stronger absorption peak at 416 nm for the test sample with different cholesterol concentration; (2) There is a shoulder peak between 450 and 500 nm, whose central wavelength is 460 nm; (3) There is a weaker peak at 578 nm; (4) Absorption spectrums shape of different cholesterol concentration is different obviously. The absorption spectrum of serum is the synthesis result of cholesterol and other components (such as sugar), and the information is contained at each wavelength. There is no significant correlation between absorbance and cholesterol content at 416 nm, showing a random relation, so whether cholesterol content is abnormal is not determined by the absorbance peak at 416 nm. Based on the evident correlation between serum absorption spectrum and cholesterol concentration in the wave band of 455-475 nm, a neural network model was built to predict the cholesterol concentration. The correlation coefficient between predicted cholesterol content output A and objectives T reaches 0.968, which can be regarded as better prediction, and it provides a spectra test method of cholesterol concentration.

  6. A novel acoustic sensor approach to classify seeds based on sound absorption spectra.

    PubMed

    Gasso-Tortajada, Vicent; Ward, Alastair J; Mansur, Hasib; Brøchner, Torben; Sørensen, Claus G; Green, Ole

    2010-01-01

    A non-destructive and novel in situ acoustic sensor approach based on the sound absorption spectra was developed for identifying and classifying different seed types. The absorption coefficient spectra were determined by using the impedance tube measurement method. Subsequently, a multivariate statistical analysis, i.e., principal component analysis (PCA), was performed as a way to generate a classification of the seeds based on the soft independent modelling of class analogy (SIMCA) method. The results show that the sound absorption coefficient spectra of different seed types present characteristic patterns which are highly dependent on seed size and shape. In general, seed particle size and sphericity were inversely related with the absorption coefficient. PCA presented reliable grouping capabilities within the diverse seed types, since the 95% of the total spectral variance was described by the first two principal components. Furthermore, the SIMCA classification model based on the absorption spectra achieved optimal results as 100% of the evaluation samples were correctly classified. This study contains the initial structuring of an innovative method that will present new possibilities in agriculture and industry for classifying and determining physical properties of seeds and other materials.

  7. On accelerator-based neutron sources and neutron field characterization with low energy neutron spectrometer based on position sensitive 3He counter.

    PubMed

    Murata, I; Miyamaru, H; Kato, I; Mori, Y

    2009-07-01

    The development of new neutron sources for BNCT applications, based on particle accelerators is currently underway all over the world. Though nuclear reactors were used for a long time as the only neutron source available having the requested flux levels, the accelerator-based ones have recently been investigated on the other hand due to its easy-to-use and acceptable performances. However, when using an accelerator, various secondary particles would be emitted which forms a troublesome background. Moreover, the neutrons produced have usually an energy spectrum somewhat different from the requested one and thus should be largely moderated. An additional issue to be taken into account is the patient positioning, which should be close to the neutron source, in order to take advantage of a neutron flux level high enough to limit the BNCT treatment time within 1h. This implies that, inside a relatively narrow space, neutrons should be moderated, while unnecessary secondary particles should be shielded. Considering that a background-free neutron field from an accelerator-driven neutron source dedicated to BNCT application is generally difficult to be provided, the characterization of such a neutron field will have to be clearly assessed. In the present study, a low energy neutron spectrometer has been thus designed and is now being developed to measure the accelerator-based neutron source performance. The presently proposed spectrometer is based on a (3)He proportional counter, which is 50 cm long and 5 cm in diameter, with a gas pressure of 0.5 MPa. It is quite unique that the spectrometer is set up in parallel with the incident neutron beam and a reaction depth distribution is measured by it as a position sensitive detector. Recently, a prototype detector has been developed and the signal test is now underway. In this paper, the feature of the accelerator-based neutron sources is outlined and importance of neutron field characterization is discussed. And the developed

  8. Ultra Compact Imaging Spectrometer (UCIS)

    NASA Astrophysics Data System (ADS)

    Blaney, Diana L.; Green, Robert; Mouroulis, Pantazis; Cable, Morgan; Ehlmann, Bethany; Haag, Justin; Lamborn, Andrew; McKinley, Ian; Rodriguez, Jose; van Gorp, Byron

    2016-10-01

    The Ultra Compact Imaging Spectrometer (UCIS) is a modular visible to short wavelength infrared imaging spectrometer architecture which could be adapted to a variety of mission concepts requiring low mass and low power. Imaging spectroscopy is an established technique to address complex questions of geologic evolution by mapping diagnostic absorption features due to minerals, organics, and volatiles throughout our solar system. At the core of UCIS is an Offner imaging spectrometer using M3 heritage and a miniature pulse tube cryo-cooler developed under the NASA Maturation of Instruments for Solar System Exploration (MatISSE) program to cool the focal plane array. The TRL 6 integrated spectrometer and cryo-cooler provide a basic imaging spectrometer capability that is used with a variety of fore optics to address lunar, mars, and small body science goals. Potential configurations include: remote sensing from small orbiters and flyby spacecraft; in situ panoramic imaging spectroscopy; and in situ micro-spectroscopy. A micro-spectroscopy front end is being developed using MatISSE funding with integration and testing planned this summer.

  9. Introducing VESPA-22: a ground-based microwave spectrometer for measuring middle atmospheric water vapour at polar latitudes

    NASA Astrophysics Data System (ADS)

    Bertagnolio, P. P.; Muscari, G.; Fiorucci, I.; Mari, M.

    2012-04-01

    We present the latest updates on the project VESPA-22 (water Vapour Emission Spectrometer for Polar Atmospheres at 22 GHz), a ground-based microwave instrument developed for long-term observations of water vapour in the polar stratosphere and mesosphere (SMWV). The short- and long-term change in water vapour concentration from the lower stratosphere to the mesosphere is one of the main areas of interest for atmospheric composition studies in the current decade. In fact, SMWV influences the temperature of the stratosphere by radiative processes, the concentration of several chemical species (also through the production of OH) and the formation of aerosols. Recent studies showed that in the last 30 years mid-latitude SMWV has been changing for mechanisms not yet fully understood. Model studies indicate that these changes could have had a significant impact (25-30%) on the tropospheric radiative forcing and surface temperature trends observed since 1980. Moreover, at polar regions, changes in SMWV strongly affect the formation rate of polar stratospheric clouds, both directly (how much is available for uptake on PSC particles) and indirectly (impact on stratospheric temperature). This is especially critical in the Arctic stratosphere where temperatures are not as cold they are over Antarctica and, for the purpose of denitrification and ozone depletion processes, an increase in SMWV of 1 ppmv is modelled to be equivalent to a 1 K decrease in temperature. In the past decade, satellite-based instruments have provided accurate and global measurements of SMWV, but a similar coverage is not expected in this decade. Conversely, the ground-based microwave spectrometers currently active provide both the long-time series necessary for decadal scale monitoring and the high time resolution (a few hours) needed to understand fast dynamical processes. Today, none of these sustained SMWV measurements are being carried out at polar regions. Our observation technique is based on the

  10. IR spectrometers for Venus and Mars measurements

    NASA Astrophysics Data System (ADS)

    Drummond, Rachel; Neefs, Eddy; Vandaele, Ann C.

    2012-07-01

    The SOIR spectrometer [1] is an infra-red spectrometer that has performed over 500 solar occultation measurements of the Venus atmosphere, profiling major and minor constituents and studying aerosol absorption, temperature and pressure effects. NOMAD is a 3-channel spectrometer for Mars occultation, limb and nadir measurements. 2 channels are infra-red, the other UV-visible. We will present the technology that enables SOIR and NOMAD to get to parts per billion mixing ratio sensitivities for trace atmospheric components and highlight the improvements made to the SOIR design to enable nadir viewing with NOMAD. Key components include the Acousto-Optical Tunable Filter with radio frequency driver that allows these spectrometers to select the wavelength domain under observation with no need for mechanical moving parts. It also allows background measurements because it is opaque when no RF is applied. The grating with 4 grooves/mm is a very hard to manufacture optical component, and suppliers were very difficult to find. The detector-cooler combination (working at 90K) is from Sofradir/Ricor and the model on board Venus Express is still working after 6 years in space (more on/off cycles that ON hour lifetime problem). The detector MCT mix is slightly altered for nadir observation, in order to reduce thermal background noise and the nadir channel spectrometer is cooled down to 173K by a large V-groove radiator. All the optical components have been enlarged to maximise signal throughput and the slit (that determines spatial and spectral resolution) has also been increased. The spacecraft attitude control system switches from yaw steering for nadir to inertial pointing for solar occultations. 1. Nevejans, D., E. Neefs, E. Van Ransbeeck, S. Berkenbosch, R. Clairquin, L. De Vos, W. Moelans, S. Glorieux, A. Baeke, O. Korablev, I. Vinogradov, Y. Kalinnikov, B. Bach, J.P. Dubois, and E. Villard, Compact high-resolution space-borne echelle grating spectrometer with AOTF based on

  11. The effects of isomaltulose, isomalt, and isomaltulose-based oligomers on mineral absorption and retention.

    PubMed

    Kashimura, J; Kimura, M; Itokawa, Y

    1996-09-01

    We carried out a balance study to examine the effects of isomaltulose, lactose, isomalt, and isomaltulose-based oligomers (IBOs) on mineral (calcium, magnesium, phosphorus, and iron) absorption and retention. Four-week-old male Wistar rats were divided into five groups of six rats each and fed a basal diet or diet the containing either 5% isomaltulose, 5% lactose, 5% isomalts or isomaltulose-based oligomers (IBOs) ad libitum for 16 d. After 1 wk, the animals were subjected to a 5-d mineral (calcium, magnesium, phosphorus, and iron) balance study. The isomalt feeding, as well as the IBOs feeding, led to significantly elevated mineral absorption and retention. On the other hand, lactose feeding, widely known to enhance calcium absorption, increased only calcium absorption and isomaltulose feeding did not affect mineral absorption or retention. The organic acids in cecum contents were increased by IBOs or isomalt feeding. Succinic and acetic acids in cecum contents were significantly increased by IBOs feeding. Similarly, succinic, acetic, and i-valeric acids and total amount of organic acid in cecum content were significantly increased by isomalt feeding. Although the organic acids in cecum contents were increased by IBOs or isomalt feeding, the pH values and acidity in cecum contents were not changed by IBOs or isomalt feeding. The effect of addition of various organic acids to the mucosal fluid was examined with in vitro study using a hindgut segment. By the addition of acetic acid, and butyric acid, the mineral (calcium, magnesium, and phosphorus) uptake was increased.

  12. Synchrotron radiation based Mössbauer absorption spectroscopy of various nuclides

    NASA Astrophysics Data System (ADS)

    Masuda, Ryo; Kobayashi, Yasuhiro; Kitao, Shinji; Kurokuzu, Masayuki; Saito, Makina; Yoda, Yoshitaka; Mitsui, Takaya; Seto, Makoto

    2016-12-01

    Synchrotron-radiation (SR) based Mössbauer absorption spectroscopy of various nuclides is reviewed. The details of the measuring system and analysis method are described. Especially, the following two advantages of the current system are described: the detection of internal conversion electrons and the close distance between the energy standard scatterer and the detector. Both of these advantages yield the enhancement of the counting rate and reduction of the measuring time. Furthermore, SR-based Mössbauer absorption spectroscopy of 40K, 151Eu, and 174Yb is introduced to show the wide applicability of this method. In addition to these three nuclides, SR-based Mössbauer absorption spectroscopy of 61Ni, 73Ge, 119Sn, 125Te, 127I, 149Sm, and 189Os has been performed. We continue to develop the method to increase available nuclides and to increase its ease of use. The complementary relation between the time-domain method using SR, such as nuclear forward scattering and the energy-domain methods such as SR-based Mössbauer absorption spectroscopy is also noted.

  13. Prototype explosives detection system based on nuclear resonance absorption in nitrogen

    SciTech Connect

    Morgado, R.E.; Arnone, G.; Cappiello, C.C.; Gardner, S.D.; Hollas, C.L.; Ussery, L.E.; White, J.M.; Zahrt, J.D.; Krauss, R.A.

    1993-12-01

    A-prototype explosives detection system that was developed for experimental evaluation of a nuclear resonance absorption techniques is described. The major subsystems are a proton accelerator and beam transport, high-temperature proton target, an airline-luggage tomographic inspection station, and an image-processing/detection- alarm subsystem. The detection system performance, based on a limited experimental test, is reported.

  14. A High Precision Scanning Control System For A VUV Fourier Transform Spectrometer

    SciTech Connect

    De Oliveira, N.; Nahon, L.; Polack, F.; Joyeux, D.; Phalippou, D.; Rodier, J. C.; Vervloeet, M.

    2007-01-19

    A VUV Fourier transform spectrometer based on a wavefront division interferometer has been built. Our ultimate goal is to provide a high resolution absorption spectrometer in the 140 - 40 nm range using the new third generation French synchrotron source Soleil as the background continuum. Here, we present the design and latest performance of the instrument scanning control system. It is based on multiple reflections of a monomode, frequency-stabilized HeNe laser between two plane mirrors allowing the required sensitivity on the displacement of the interferometer mobile arm. The experimental results on the sampling precision show an rms error below 5 nm for a travel length of 7.5 mm.

  15. An Alpha-Particle Energy Spectrometer Based on the BBC Micro.

    ERIC Educational Resources Information Center

    Bishop, Richard

    1988-01-01

    Concentrates on describing the implementation of the hardware systems based on the BBC microcomputer. Describes the electronic systems used to amplify the signals from the detector and to convert the signal to digital format. Discusses the software that must be used and the system performance. (CW)

  16. Enhanced light absorption in thin film silicon solar cells with Fourier-series based periodic nanostructures.

    PubMed

    Guo, Xiaowei; Wang, Dashuai; Liu, Bang; Li, Shaorong; Sheng, Xing

    2016-01-25

    We proposed a Fourier-series based periodic nanostructure(FSPN) for light trapping in thin film silicon solar cells. By globally optimizing the Fourier coefficients across entire silicon absorption spectrum, we obtained a FSPN structure with short circuit current density greater than 24 mA/cm(2) for a 1μm real silicon absorption layer. The spectral analysis shows at normal incidence the FSPN exhibits a collection effect of periodic gratings and performs over 84.6% better than random texture. The angular analysis shows that the FSPN outperforms grating and random textures within 70 °.

  17. Refractive index and absorption detector for liquid chromatography based on Fabry-Perot interferometry

    DOEpatents

    Yeung, E.S.; Woodruff, S.D.

    1984-06-19

    A refractive index and absorption detector are disclosed for liquid chromatography. It is based in part on a Fabry-Perot interferometer and is used for the improved detection of refractive index and absorption. It includes a Fabry-Perot interferometer having a normally fixed first partially reflecting mirror and a movable second partially reflecting mirror. A chromatographic flow-cell is positioned between the mirrors along the optical axis of a monochromatic laser beam passing through the interferometer. A means for deriving information about the interference fringes coming out of the interferometer is used with a mini-computer to compute the refractive index of the specimen injected into the flow cell. The minicomputer continuously scans the interferometer for continuous refractive index readings and outputs the continuous results of the scans on a chart recorder. The absorption of the specimen can concurrently be scanned by including a second optical path for an excitation laser which will not interfere with the first laser, but will affect the specimen so that absorption properties can be detected. By first scanning for the refractive index of the specimen, and then immediately adding the excitation laser and subsequently scanning for the refractive index again, the absorption of the specimen can be computed and recorded. 10 figs.

  18. Refractive index and absorption detector for liquid chromatography based on Fabry-Perot interferometry

    DOEpatents

    Yeung, Edward S.; Woodruff, Steven D.

    1984-06-19

    A refractive index and absorption detector for liquid chromatography. It is based in part on a Fabry-Perot interferometer and is used for the improved detection of refractive index and absorption. It includes a Fabry-Perot interferometer having a normally fixed first partially reflecting mirror and a movable second partially reflecting mirror. A chromatographic flow-cell is positioned between the mirrors along the optical axis of a monochromatic laser beam passing through the interferometer. A means for deriving information about the interference fringes coming out of the interferometer is used with a mini-computer to compute the refractive index of the specimen injected into the flow cell. The minicomputer continuously scans the interferometer for continuous refractive index readings and outputs the continuous results of the scans on a chart recorder. The absorption of the specimen can concurrently be scanned by including a second optical path for an excitation laser which will not interfere with the first laser, but will affect the specimen so that absorption properties can be detected. By first scanning for the refractive index of the specimen, and then immediately adding the excitation laser and subsequently scanning for the refractive index again, the absorption of the specimen can be computed and recorded.

  19. Research on filling process of fuel and oxidant during detonation based on absorption spectrum technology

    NASA Astrophysics Data System (ADS)

    Lv, Xiao-Jing; Li, Ning; Weng, Chun-Sheng

    2014-12-01

    Research on detonation process is of great significance for the control optimization of pulse detonation engine. Based on absorption spectrum technology, the filling process of fresh fuel and oxidant during detonation is researched. As one of the most important products, H2O is selected as the target of detonation diagnosis. Fiber distributed detonation test system is designed to enable the detonation diagnosis under adverse conditions in detonation process. The test system is verified to be reliable. Laser signals at different working frequency (5Hz, 10Hz and 20Hz) are detected. Change of relative laser intensity in one detonation circle is analyzed. The duration of filling process is inferred from the change of laser intensity, which is about 100~110ms. The peak of absorption spectrum is used to present the concentration of H2O during the filling process of fresh fuel and oxidant. Absorption spectrum is calculated, and the change of absorption peak is analyzed. Duration of filling process calculated with absorption peak consisted with the result inferred from the change of relative laser intensity. The pulse detonation engine worked normally and obtained the maximum thrust at 10Hz under experiment conditions. The results are verified through H2O gas concentration monitoring during detonation.

  20. Three-dimensional superwetting mesh film based on graphene assembly for liquid transportation and selective absorption.

    PubMed

    Sun, Hanxue; Li, An; Qin, Xiaojuan; Zhu, Zhaoqi; Liang, Weidong; An, Jin; La, Peiqing; Deng, Weiqiao

    2013-12-01

    Superwetting membranes or porous absorbent materials have recently attracted considerable interest from both commercial and academic communities due to their excellent performance for separation or selective absorption of organic compounds and oils from water, which shows great potential for addressing environmental issues. Herein, the first example of engineering a commercially available stainless-steel grid based on the assembly of graphene for the fabrication of superwetting mesh films (SMFs) is reported. An excellent surface wettability of the SMFs, which exhibit a unique adhesion force to liquids, is observed; this makes it possible to transfer small quantities of liquid samples to perform microsample analysis. A three-dimensional SMF shows unprecedented performance in the separation, transportation, and selective absorption of organic compounds or oils from water. The performance is considerably improved in comparison to traditional separation/absorption technologies and may useful for a wide range of applications such as purification, water treatment, or oil-spill cleanup.

  1. Optical Absorption Microspectroscopy (μ-OAS) Based on Schwarzschild-Type Cassegrain Optics.

    PubMed

    Chassé, Mathieu; Lelong, Gérald; van Nijnatten, Peter; Schoofs, Ivo; de Wolf, Jürgen; Galoisy, Laurence; Calas, Georges

    2015-04-01

    A new experimental setup, combining a custom-designed Schwarzschild-type Cassegrain-based microscope and an ultraviolet-visible-near infrared (UV-Vis-NIR) spectrophotometer, has been developed, focusing the light beam down to 20 μm diameter. Optical absorption spectra (in the 300-2500 nm range) have been measured on micrometer-sized natural glass inclusions providing information on iron speciation in magmatic melts. The absence of contribution from the host crystal matrix provides a test of the efficiency of micro-focusing. A microthermometric stage has been adapted on the microscope for measuring optical absorption spectra up to 900 K with application to the thermochromism of minute natural spinel crystals (MgAl2O4:Fe(2+),Cr(3+)). This experimental setup provides an easy and fast way to follow the evolution of spectral properties and color of glasses or crystals with temperature as well as the possibility of measuring spatially resolved optical absorption spectra.

  2. The tuning of light-matter coupling and dichroism in graphene for enhanced absorption: Implications for graphene-based optical absorption devices

    NASA Astrophysics Data System (ADS)

    Rakheja, Shaloo; Sengupta, Parijat

    2016-03-01

    The inter-band optical absorption in graphene characterized by its fine-structure constant has a universal value of 2.3% independent of the material parameters. However, for several graphene-based photonic applications, enhanced optical absorption is highly desired. In this work, we quantify the tunability of optical absorption in graphene via the Fermi level, angle of incidence of the incident polarized light, and the dielectric constants of the surrounding dielectric media in which graphene is embedded. The influence of impurities adsorbed on the surface of graphene on the Lorentzian broadening of the spectral function of the density of states is analytically evaluated within the equilibrium Green’s function formalism. In all the cases, we find that absorption of light graphene embedded in dielectric medium is significantly higher than 2.3%. We also compute the differential absorption of right and left circularly-polarized light in graphene that is uniaxially and optically strained. The preferential absorption or circular dichroism is investigated for armchair and zigzag strain and the interplay of k-space and velocity anisotropy is examined. Finally, we relate circular dichroism to the Berry curvature of gapped graphene and explain the connection to parameters that define the underlying Hamiltonian.

  3. A multiparameter data acquisition system based on universal serial bus interface for electron momentum spectrometer

    SciTech Connect

    Ning, C.G.; Deng, J.K.; Su, G.L.; Zhou, H.; Ren, X.G.

    2004-09-01

    A versatile multiparameter data acquisition system based on universal serial bus (USB) interface was designed and has been used on the electron momentum spectromenter. Digitized data were first buffered in a FIFO memory in an event-by-event mode with a check bit, and then transferred to computer through the USB interface. USB interface combined with a microcontroller unit provides much flexibility for data acquisition and experimental controls. The operation performance of the system is demonstrated in the measurement of electron momentum spectra of CH{sub 2}F{sub 2} molecules.

  4. A multiparameter data acquisition system based on universal serial bus interface for electron momentum spectrometer

    NASA Astrophysics Data System (ADS)

    Ning, C. G.; Deng, J. K.; Su, G. L.; Zhou, H.; Ren, X. G.

    2004-09-01

    A versatile multiparameter data acquisition system based on universal serial bus (USB) interface was designed and has been used on the electron momentum spectromenter. Digitized data were first buffered in a FIFO memory in an event-by-event mode with a check bit, and then transferred to computer through the USB interface. USB interface combined with a microcontroller unit provides much flexibility for data acquisition and experimental controls. The operation performance of the system is demonstrated in the measurement of electron momentum spectra of CH2F2 molecules.

  5. Performance of the NIST goniocolorimeter with a broad-band source and multichannel charged coupled device based spectrometer.

    PubMed

    Podobedov, V B; Miller, C C; Nadal, M E

    2012-09-01

    The authors describe the NIST high-efficiency instrument for measurements of bidirectional reflectance distribution function of colored materials, including gonioapparent materials such as metallic and pearlescent coatings. The five-axis goniospectrometer measures the spectral reflectance of samples over a wide range of illumination and viewing angles. The implementation of a broad-band source and a multichannel CCD spectrometer corrected for stray light significantly increased the efficiency of the goniometer. In the extended range of 380 nm to 1050 nm, a reduction of measurement time from a few hours to a few minutes was obtained. Shorter measurement time reduces the load on the precise mechanical assembly ensuring high angular accuracy over time. We describe the application of matrix-based correction of stray light and the extension of effective dynamic range of measured fluxes to the values of 10(6) to 10(7) needed for the absolute characterization of samples. The measurement uncertainty was determined to be 0.7% (k = 2), which is comparable with similar instruments operating in a single channel configuration. Several examples of reflectance data obtained with the improved instrument indicate a 0.3% agreement compared to data collected with the single channel configuration.

  6. A lab-based ambient pressure x-ray photoelectron spectrometer with exchangeable analysis chambers

    SciTech Connect

    Newberg, John T. Arble, Chris; Goodwin, Chris; Khalifa, Yehia; Broderick, Alicia; Åhlund, John

    2015-08-15

    Ambient pressure X-ray photoelectron spectroscopy (APXPS) is a powerful spectroscopy tool that is inherently surface sensitive, elemental, and chemical specific, with the ability to probe sample surfaces under Torr level pressures. Herein, we describe the design of a new lab-based APXPS system with the ability to swap small volume analysis chambers. Ag 3d(5/2) analyses of a silver foil were carried out at room temperature to determine the optimal sample-to-aperture distance, x-ray photoelectron spectroscopy analysis spot size, relative peak intensities, and peak full width at half maximum of three different electrostatic lens modes: acceleration, transmission, and angular. Ag 3d(5/2) peak areas, differential pumping pressures, and pump performance were assessed under varying N{sub 2}(g) analysis chamber pressures up to 20 Torr. The commissioning of this instrument allows for the investigation of molecular level interfacial processes under ambient vapor conditions in energy and environmental research.

  7. The Data Acquisition System For Multichannel Spectrometer On Base Of The NGDP Framework

    NASA Astrophysics Data System (ADS)

    Isupov, A. Yu.; Kovtun, V. E.; Foshchan, A. G.

    2010-04-01

    In present work it is proposed to implement the data acquisition system (DAQ COMBAS) for the fragment—separator COMBAS under freely distributed UNIX—like operating system (OS) FreeBSD on base of the ngdp framework, which allows to build modular distributed DAQ. As a CAMAC subsystem the camac package (DLNP JINR) is used, which encapsulates code deals with each supported crate controller into corresponding driver. Authors create the driver kh(4) for the PCI adapter of the CC02 controller (Karazin Kharkov National University). The runtime configurable r2h(1) histogram server module is supposed. The histGUI(1) client module is intended for histograms viewing as well as for r2h(1) runtime control and configurating. The histGUI(1) client will not depend on DAQ and ngdp system libraries, so can be compiled under any OS equipped by the ROOT package.

  8. A lab-based ambient pressure x-ray photoelectron spectrometer with exchangeable analysis chambers

    NASA Astrophysics Data System (ADS)

    Newberg, John T.; Åhlund, John; Arble, Chris; Goodwin, Chris; Khalifa, Yehia; Broderick, Alicia

    2015-08-01

    Ambient pressure X-ray photoelectron spectroscopy (APXPS) is a powerful spectroscopy tool that is inherently surface sensitive, elemental, and chemical specific, with the ability to probe sample surfaces under Torr level pressures. Herein, we describe the design of a new lab-based APXPS system with the ability to swap small volume analysis chambers. Ag 3d(5/2) analyses of a silver foil were carried out at room temperature to determine the optimal sample-to-aperture distance, x-ray photoelectron spectroscopy analysis spot size, relative peak intensities, and peak full width at half maximum of three different electrostatic lens modes: acceleration, transmission, and angular. Ag 3d(5/2) peak areas, differential pumping pressures, and pump performance were assessed under varying N2(g) analysis chamber pressures up to 20 Torr. The commissioning of this instrument allows for the investigation of molecular level interfacial processes under ambient vapor conditions in energy and environmental research.

  9. A lab-based ambient pressure x-ray photoelectron spectrometer with exchangeable analysis chambers.

    PubMed

    Newberg, John T; Åhlund, John; Arble, Chris; Goodwin, Chris; Khalifa, Yehia; Broderick, Alicia

    2015-08-01

    Ambient pressure X-ray photoelectron spectroscopy (APXPS) is a powerful spectroscopy tool that is inherently surface sensitive, elemental, and chemical specific, with the ability to probe sample surfaces under Torr level pressures. Herein, we describe the design of a new lab-based APXPS system with the ability to swap small volume analysis chambers. Ag 3d(5/2) analyses of a silver foil were carried out at room temperature to determine the optimal sample-to-aperture distance, x-ray photoelectron spectroscopy analysis spot size, relative peak intensities, and peak full width at half maximum of three different electrostatic lens modes: acceleration, transmission, and angular. Ag 3d(5/2) peak areas, differential pumping pressures, and pump performance were assessed under varying N2(g) analysis chamber pressures up to 20 Torr. The commissioning of this instrument allows for the investigation of molecular level interfacial processes under ambient vapor conditions in energy and environmental research.

  10. Method and apparatus for digitally based high speed x-ray spectrometer

    DOEpatents

    Warburton, William K.; Hubbard, Bradley

    1997-01-01

    A high speed, digitally based, signal processing system which accepts input data from a detector-preamplifier and produces a spectral analysis of the x-rays illuminating the detector. The system achieves high throughputs at low cost by dividing the required digital processing steps between a "hardwired" processor implemented in combinatorial digital logic, which detects the presence of the x-ray signals in the digitized data stream and extracts filtered estimates of their amplitudes, and a programmable digital signal processing computer, which refines the filtered amplitude estimates and bins them to produce the desired spectral analysis. One set of algorithms allow this hybrid system to match the resolution of analog systems while operating at much higher data rates. A second set of algorithms implemented in the processor allow the system to be self calibrating as well. The same processor also handles the interface to an external control computer.

  11. Method and apparatus for digitally based high speed x-ray spectrometer

    DOEpatents

    Warburton, W.K.; Hubbard, B.

    1997-11-04

    A high speed, digitally based, signal processing system which accepts input data from a detector-preamplifier and produces a spectral analysis of the x-rays illuminating the detector. The system achieves high throughputs at low cost by dividing the required digital processing steps between a ``hardwired`` processor implemented in combinatorial digital logic, which detects the presence of the x-ray signals in the digitized data stream and extracts filtered estimates of their amplitudes, and a programmable digital signal processing computer, which refines the filtered amplitude estimates and bins them to produce the desired spectral analysis. One set of algorithms allow this hybrid system to match the resolution of analog systems while operating at much higher data rates. A second set of algorithms implemented in the processor allow the system to be self calibrating as well. The same processor also handles the interface to an external control computer. 19 figs.

  12. Line-Parameter Measurements and Stringent Tests of Line-Shape Models Based on Cavity-Enhanced Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Bielska, Katarzyna; Fleisher, Adam J.; Hodges, Joseph T.; Lin, Hong; Long, David A.; Reed, Zachary D.; Sironneau, Vincent; Truong, Gar-Wing; Wójtewicz, Szymon

    2014-06-01

    Laser methods that are based on cavity-enhanced absorption spectroscopy (CEAS) are well-suited for measuring molecular line parameters under conditions of low optical density, and as such they are complementary to broadband Fourier-transform spectroscopy (FTS) techniques. Attributes of CEAS include relatively low detection limits, accurate and precise detuning axes and high fidelity measurements of line shape. In many cases these performance criteria are superior to those obtained using direct laser absorption spectroscopy and FTS-based systems. In this presentation we will survey several examples of frequency-stabilized cavity ring-down spectroscopy (FS-CRDS)1 measurements obtained with laser spectrometers developed at the National Institute of Standards and Technology (NIST) in Gaithersburg Maryland. These experiments, which are motivated by atmospheric monitoring and remote-sensing applications that require high-precision and accuracy, involve nearinfrared transitions of carbon dioxide, water, oxygen and methane. We discuss spectra with signal-to-noise ratios exceeding 106, frequency axes with absolute uncertainties in the 10 kHz to 100 kHz range and linked to a Cs clock, line parameters with relative uncertainties at the 0.2 % level and isotopic ratios measured with a precision of 0.03 %. We also present FS-CRDS measurements of CO2 line intensities which are measured at atmospheric concentration levels and linked to gravimetric standards for CO2 in air, and we quantify pressure-dependent deviations between various theoretical line profiles and measured line shapes. Finally we also present recent efforts to increase data throughput and spectral coverage in CEAS experiments. We describe three new high-bandwidth CEAS techniques including frequency-agile, rapid scanning spectroscopy (FARS)2, which enables continuous-wave measurements of cavity mode linewidth and acquisition of ringdown decays with no dead time during laser frequency tuning, heterodyne

  13. Imaging soft x-ray spectrometers based on superconducting tunnel junctions

    NASA Astrophysics Data System (ADS)

    Verhoeve, P.; Martin, D. D. E.; Venn, R.

    2010-07-01

    X-ray detectors based on superconducting tunnel junctions (STJs) have demonstrated good energy resolution in the soft X-ray energy range 0.1-6 keV. In particular DROIDS (Distributed Read Out Imaging Devices), consisting of a superconducting absorber strip with superconducting tunnel junctions as read-out devices on either end, could combine this high resolving power with a large sensitive area and good soft X-ray detection efficiency. In this paper we present results on the spectroscopic performance of Al and Ta/Al DROIDs with different absorber materials (Ta, Re) and with variations in absorber configurations: our standard absorber integrated with the read-out structure is compared with absorbers deposited after definition of the read-out structure. The latter allows maximising the detection efficiency through thicker layers and different absorber materials. Also, absorbers which are electrically coupled to the readout structure are compared to insulated absorbers which couple to the readout structure by phonon exchange across a thin dielectric layer. New process routes have been designed for all new configurations. Whilst not all these structures have been fabricated successfully yet, our integrated absorber sofar exhibits the best performance, with 2.45 eV FWHM at 400 eV and 16.6 eV FWHM at 5.9 keV.

  14. Chemical detection using the airborne thermal infrared imaging spectrometer (TIRIS)

    SciTech Connect

    Gat, N.; Subramanian, S.; Sheffield, M.; Erives, H.; Barhen, J.

    1997-04-01

    A methodology is described for an airborne, downlooking, longwave infrared imaging spectrometer based technique for the detection and tracking of plumes of toxic gases. Plumes can be observed in emission or absorption, depending on the thermal contrast between the vapor and the background terrain. While the sensor is currently undergoing laboratory calibration and characterization, a radiative exchange phenomenology model has been developed to predict sensor response and to facilitate the sensor design. An inverse problem model has also been developed to obtain plume parameters based on sensor measurements. These models, the sensors, and ongoing activities are described.

  15. Modeling of the Temperature Effect on Oxygen Absorption by Iron-Based Oxygen Scavengers.

    PubMed

    Polyakov, Vladimir A; Miltz, Joseph

    2016-01-01

    A new engineering-oriented model for prediction of the effect of temperature on the kinetics of oxygen absorption by iron-based oxygen scavengers (IOSs) was developed. The model is based on the physicochemical mechanism of the O2 scavenging process by the active component of the IOS (iron powder). The conclusions of this study are: (1) the iron deposits formed on the iron particles are composed of 2 different layers: an inner layer of Fe3 O4 and an outer layer of FeOOH that vanishes with the depletion of oxygen. (2) The model considers the chemical processes in the heterogeneous closed system "Fe-H2 O-NaCl-O2 " and describes the kinetics of oxygen absorption by the powder, depending on the characteristics of the system. (3) The nonlinear ordinary differential equation (ODE) of the O2 absorption kinetics was derived and a simple approximate solution to this ODE was obtained theoretically that is similar to the empirical exponential formula published in the relevant literature. (4) The temperature dependence of the oxygen absorption rate is more complicated than that described by the Arrhenius equation.

  16. Diffuse reflectance relations based on diffusion dipole theory for large absorption and reduced scattering

    NASA Astrophysics Data System (ADS)

    Bremmer, Rolf H.; van Gemert, Martin J. C.; Faber, Dirk J.; van Leeuwen, Ton G.; Aalders, Maurice C. G.

    2013-08-01

    Diffuse reflectance spectra are used to determine the optical properties of biological samples. In medicine and forensic science, the turbid objects under study often possess large absorption and/or scattering properties. However, data analysis is frequently based on the diffusion approximation to the radiative transfer equation, implying that it is limited to tissues where the reduced scattering coefficient dominates over the absorption coefficient. Nevertheless, up to absorption coefficients of 20 m at reduced scattering coefficients of 1 and 11.5 mm-1, we observed excellent agreement (r2=0.994) between reflectance measurements of phantoms and the diffuse reflectance equation proposed by Zonios et al. [Appl. Opt. 38, 6628-6637 (1999)], derived as an approximation to one of the diffusion dipole equations of Farrell et al. [Med. Phys. 19, 879-888 (1992)]. However, two parameters were fitted to all phantom experiments, including strongly absorbing samples, implying that the reflectance equation differs from diffusion theory. Yet, the exact diffusion dipole approximation at high reduced scattering and absorption also showed agreement with the phantom measurements. The mathematical structure of the diffuse reflectance relation used, derived by Zonios et al. [Appl. Opt. 38, 6628-6637 (1999)], explains this observation. In conclusion, diffuse reflectance relations derived as an approximation to the diffusion dipole theory of Farrell et al. can analyze reflectance ratios accurately, even for much larger absorption than reduced scattering coefficients. This allows calibration of fiber-probe set-ups so that the object's diffuse reflectance can be related to its absorption even when large. These findings will greatly expand the application of diffuse reflection spectroscopy. In medicine, it may allow the use of blue/green wavelengths and measurements on whole blood, and in forensic science, it may allow inclusion of objects such as

  17. Diffuse reflectance relations based on diffusion dipole theory for large absorption and reduced scattering.

    PubMed

    Bremmer, Rolf H; van Gemert, Martin J C; Faber, Dirk J; van Leeuwen, Ton G; Aalders, Maurice C G

    2013-08-01

    Diffuse reflectance spectra are used to determine the optical properties of biological samples. In medicine and forensic science, the turbid objects under study often possess large absorption and/or scattering properties. However, data analysis is frequently based on the diffusion approximation to the radiative transfer equation, implying that it is limited to tissues where the reduced scattering coefficient dominates over the absorption coefficient. Nevertheless, up to absorption coefficients of 20  mm-1 at reduced scattering coefficients of 1 and 11.5  mm-1, we observed excellent agreement (r2=0.994) between reflectance measurements of phantoms and the diffuse reflectance equation proposed by Zonios et al. [Appl. Opt.38, 6628-6637 (1999)], derived as an approximation to one of the diffusion dipole equations of Farrell et al. [Med. Phys.19, 879-888 (1992)]. However, two parameters were fitted to all phantom experiments, including strongly absorbing samples, implying that the reflectance equation differs from diffusion theory. Yet, the exact diffusion dipole approximation at high reduced scattering and absorption also showed agreement with the phantom measurements. The mathematical structure of the diffuse reflectance relation used, derived by Zonios et al. [Appl. Opt.38, 6628-6637 (1999)], explains this observation. In conclusion, diffuse reflectance relations derived as an approximation to the diffusion dipole theory of Farrell et al. can analyze reflectance ratios accurately, even for much larger absorption than reduced scattering coefficients. This allows calibration of fiber-probe set-ups so that the object's diffuse reflectance can be related to its absorption even when large. These findings will greatly expand the application of diffuse reflection spectroscopy. In medicine, it may allow the use of blue/green wavelengths and measurements on whole blood, and in forensic science, it may allow inclusion of objects such as blood stains and cloth at crime

  18. A new near-infrared absorption and fluorescent probe based on bombesin for molecular imaging

    NASA Astrophysics Data System (ADS)

    Kujala, Naresh; Zhai, Huifang; Smith, Charles; Prasanphanich, Adam; Sieckman, Gary; Hoffman, Timothy; Volkert, Wynn; Ma, Lixin; Yu, Ping

    2009-02-01

    We have developed a series of new dye bombesin conjugates for site-specific absorption and fluorescence imaging of human prostate and breast cancers. Bombesin (BBN), an amphibian analog to the endogenous ligand, binds to the gastrin releasing peptide (GRP) receptors with high specificity and affinity. Previously, we developed an Alexa Fluor 680-GGG-BBN peptide conjugate which demonstrated high binding affinity and specificity for breast cancer cells in the in vitro and in vivo tests (Ref: Ma et al., Molecular Imaging, vol. 6, no. 3, 2007: 171-180). This probe can not be used as an absorption probe in near-infrared imaging because its absorption peak is in the visible wavelength range. In addition, site specific longer wavelength fluorescent probe is desired for in vivo molecular imaging because long wavelength photons penetrate deeper into tissue. The new absorption and fluorescent probe we developed is based on the last eight-residues of BBN, -Q-W-A-V-G-H-L-M-(NH2), and labeled with AlexaFluor750 through a chemical linker, beta-alanine. The new probe, Alexa Fluor 750-BetaAla-BBN(7-14)NH2, exhibits optimal pharmacokinetics for specific targeting and optical imaging of the GRP receptor over-expressing cancer cells. Absorption spectrum has been measured and showed absorption peaks at 690nm, 720nm and 735nm. Fluorescent band is located at 755nm. In vitro and in vivo investigations have demonstrated the effectiveness of the new conjugates to specifically target human cancer cells overexpressing GRP receptors and tumor xenografts in severely compromised immunodeficient mouse model.

  19. Development of mid-infrared spectrometer with an image slicer (MIRSIS) for ground-based astronomy: developing optical and mechanical mounts

    NASA Astrophysics Data System (ADS)

    Okamoto, Yoshiko Kataza; Kataza, Hirokazu; Sato, Keigo; Manabe, Kei; Mitsui, Kenji; Okada, Norio; Fukushima, Mitsuhiro; Nishino, Tetsuo; Tomita, Koji; Tosa, Masamune; Onaka, Takashi

    2008-07-01

    Mid-Infrared Spectrometer with an Image Slicer (MIRSIS) is a 10micron band spectrometer for ground-based observations. Based on the optical design reported in Okamoto et al. (2006), we recently developed most of optical elements and their mounts. There, we adopted designs based on an ultra-precision cut for the slice mirrors and the pupil mirrors. We also designed and partly manufactured the optical parts with switching/adjusting mechanism with cryogenic step motors. Since MIRSIS has a very complicated stereoscopic configuration of optical elements, we developed a method to adjust the optical alignment where relative positional markers and a three-dimensional measuring system are combined. We confirmed that we can achieve position and angular adjustment with error down to 0.1mm and 0.05degree through alignment test with a pair of mirrors.

  20. Reduction of VOC emissions by a membrane-based gas absorption process.

    PubMed

    Li, Rui; Xu, Jun; Wang, Lianjun; Li, Jiansheng; Sun, Xiuyun

    2009-01-01

    A membrane-based gas absorption (MGA) process was evaluated for the removal of volatile organic compounds (VOCs) based on C6H6/N2 mixture. The absorption of C6H6 from a C6H6/N2 mixture was investigated using a hydrophobic polypropylene hollow fiber membrane contactor and the aqueous solution of N-formyl morpholine (NFM) as absorbent. The effects of various factors on the overall mass transfer coefficient was investigated. The experimental results showed that the removal efficiency of C6H6 could reach 99.5% in present studied system. A mathematical model based on resistance-in-series concept was presented to predict the value of overall mass transfer coefficient. The average error between the predicted and experimental values is 7.9%. In addition, conventional packed columns for VOCs removal was also evaluated for comparison.

  1. Photonuclear reaction based high-energy x-ray spectrometer to cover from 2 MeV to 20 MeV

    SciTech Connect

    Sakata, S. Arikawa, Y.; Kojima, S.; Ikenouchi, T.; Nagai, T.; Abe, Y.; Inoue, H.; Morace, A.; Utsugi, M.; Nishimura, H.; Nakai, M.; Shiraga, H.; Fujioka, S.; Azechi, H.; Kato, R.

    2014-11-15

    A photonuclear-reaction-based hard x-ray spectrometer is developed to measure the number and energy spectrum of fast electrons generated by interactions between plasma and intense laser light. In this spectrometer, x-rays are converted to neutrons through photonuclear reactions, and the neutrons are counted with a bubble detector that is insensitive to x-rays. The spectrometer consists of a bundle of hard x-ray detectors that respond to different photon-energy ranges. Proof-of-principle experiment was performed on a linear accelerator facility. A quasi-monoenergetic electron bunch (N{sub e} = 1.0 × 10{sup −6} C, E{sub e} = 16 ± 0.32 MeV) was injected into a 5-mm-thick lead plate. Bremsstrahlung x-rays, which emanate from the lead plate, were measured with the spectrometer. The measured spectral shape and intensity agree fairly well with those computed with a Monte Carlo simulation code. The result shows that high-energy x-rays can be measured absolutely with a photon-counting accuracy of 50%–70% in the energy range from 2 MeV to 20 MeV with a spectral resolution (Δhν/hν) of about 15%. Quantum efficiency of this spectrometer was designed to be 10{sup −7}, 10{sup −4}, 10{sup −5}, respectively, for 2–10, 11–15, and 15–25 MeV of photon energy ranges.

  2. The portable atmospheric research interferometric spectrometer for the infrared, PARIS-IR

    NASA Astrophysics Data System (ADS)

    Fu, Dejian; Walker, Kaley A.; Sung, Keeyoon; Boone, Chris D.; Soucy, Marc-Andre; Bernath, Peter F.

    2007-01-01

    A new compact, portable Fourier transform spectrometer, called the Portable Atmospheric Research Interferometric Spectrometer for the Infrared (PARIS-IR), has been built for atmospheric remote sensing. The first comprehensive description of the configuration and performance of this instrument for ground-based and balloon-borne operation is provided. Sample atmospheric absorption spectra and representative results observed at the Waterloo Atmospheric Observatory (WAO) are given. The good agreement between PARIS IR, Brewer spectrophotometer, and ozonesonde measurements of the column density of ozone at mid-latitudes demonstrate the performance and the reliability of the instrument.

  3. Locking distributed feedback laser diode frequency to gas absorption lines based on genetic programming

    NASA Astrophysics Data System (ADS)

    Quan, Wei; Li, Guanghui; Fang, Zishan; Zhai, Yueyang; Li, Xinyi; Liu, Feng

    2017-01-01

    Distributed feedback laser is widely used as the pump beam and probe beam in atomic physical and quantum experiments. As the frequency stability is a vital characteristic to the laser diode in these experiments, a saturated absorption frequency stabilization method assisted with the function of current and frequency is proposed. The relationship between the current and frequency is acquired based on the genetic programming (GP) algorithm. To verify the feasibility of the method, the frequency stabilization system is comprised of two parts that are modeling the relation between the current and frequency by GP and processing the saturated absorption signal. The results of the frequency stabilization experiment proved that this method can not only narrow the frequency searching range near the atomic line center but also compensate for the phase delay between the saturated absorption peak and the zero crossing point of the differential error signal. The reduced phase delay increases the locking probability and makes the wavelength drift only 0.015 pm/h, which converted to frequency drift is 7 MHz/h after frequency locking on the Rb absorption line.

  4. Carbon-Nanohorn Based Nanofluids for a Direct Absorption Solar Collector for Civil Application.

    PubMed

    Moradi, A; Sani, E; Simonetti, M; Francini, F; Chiavazzo, E; Asinari, P

    2015-05-01

    Direct solar absorption has been often considered in the past as a possible solution for solar thermal collectors for residential and small commercial applications. A direct absorption could indeed improve the performance of solar collectors by skipping one step of the heat transfer mechanism in standard devices and having a more convenient temperature distribution inside the collector. Classical solar thermal collectors have a metal sheet as absorber, designed such that water has the minimum temperature in each transversal section, in order to collect as much solar thermal energy as possible. On the other hand, in a direct configuration, the hottest part of the system is the operating fluid and this allows to have a more efficient conversion. Nanofluids, i.e., fluids with a suspension of nanoparticles, such as carbon nanohorns, could be a good and innovative family of absorbing fluids owing to their higher absorption coefficient compared to the base fluid and stability under moderate temperature gradients. Moreover, carbon nanohorns offer the remarkable advantage of a reduced toxicity over other carbon nanoparticles. In this work, a three-dimensional model of the absorption phenomena in nanofluids within a cylindrical tube is coupled with a computational fluid dynamics (CFD) analysis of the flow and temperature field. Measured optical properties of nanofluids at different concentrations have been implemented in the model. Heat losses due to conduction, convection and radiation at the boundaries are considered as well.

  5. Nonlinear absorption and optical damage threshold of carbon-based nanostructured material embedded in a protein

    NASA Astrophysics Data System (ADS)

    Janulewicz, K. A.; Hapiddin, A.; Joseph, D.; Geckeler, K. E.; Sung, J. H.; Nickles, P. V.

    2014-12-01

    Physical processes in laser-matter interaction used to be determined by generation of fast electrons resulting from efficient conversion of the absorbed laser radiation. Composite materials offer the possibility to control the absorption by choice of the host material and dopants. Reported here strong absorption of ultrashort laser pulse in a composite carbon-based nanomaterial including single-walled carbon nanotubes (SWCNTs) or multilayer graphene was measured in the intensity range between 1012 and 1016 W cm-2. A protein (lysozyme) was used as the host. The maximum absorption of femtosecond laser pulse has reached 92-96 %. The optical damage thresholds of the coatings were registered at an intensity of (1.1 ± 0.5) × 1013 W cm-2 for the embedded SWCNTs and at (3.4 ± 0.3) × 1013 W cm-2 for the embedded graphene. Encapsulated variant of the dispersed nanomaterial was investigated as well. It was found that supernatant protein in the coating material tends to dominate the absorption process, independently of the embedded nanomaterial. The opposite was observed for the encapsulated material.

  6. B1-based specific energy absorption rate determination for nonquadrature radiofrequency excitation.

    PubMed

    Katscher, Ulrich; Findeklee, Christian; Voigt, Tobias

    2012-12-01

    The current gold standard to estimate local and global specific energy absorption rate for MRI involves numerically modeling the patient and the transmit radiofrequency coil. Recently, a patient-individual method was presented, which estimated specific energy absorption rate from individually measured B(1) maps. This method, however, was restricted to quadrature volume coils due to difficulties distinguishing phase contributions from radiofrequency transmission and reception. In this study, a method separating these two phase contributions by comparing the electric conductivity reconstructed from different transmit channels of a parallel radiofrequency transmission system is presented. This enables specific energy absorption rate estimation not only for quadrature excitation but also for the nonquadrature excitation of the single elements of the transmit array. Though the contributions of the different phases are known, unknown magnetic field components and tissue boundary artifacts limit the technique. Nevertheless, the high agreement between simulated and experimental results found in this study is promising. B(1)-based specific energy absorption rate determination might become possible for arbitrary radiofrequency excitation on a patient-individual basis.

  7. Mass spectrometers: instrumentation

    NASA Astrophysics Data System (ADS)

    Cooks, R. G.; Hoke, S. H., II; Morand, K. L.; Lammert, S. A.

    1992-09-01

    Developments in mass spectrometry instrumentation over the past three years are reviewed. The subject is characterized by an enormous diversity of designs, a high degree of competition between different laboratories working with either different or similar techniques and by extremely rapid progress in improving analytical performance. Instruments can be grouped into genealogical charts based on their physical and conceptual interrelationships. This is illustrated using mass analyzers of different types. The time course of development of particular instrumental concepts is illustrated in terms of the s-curves typical of cell growth. Examples are given of instruments which are at the exponential, linear and mature growth stages. The prime examples used are respectively: (i) hybrid instruments designed to study reactive collisions of ions with surfaces: (ii) the Paul ion trap; and (iii) the triple quadrupole mass spectrometer. In the area of ion/surface collisions, reactive collisions such as hydrogen radical abstraction from the surface by the impinging ion are studied. They are shown to depend upon the chemical nature of the surface through the use of experiments which utilize self-assembled monolayers as surfaces. The internal energy deposited during surface-induced dissociation upon collision with different surfaces in a BEEQ instrument is also discussed. Attention is also given to a second area of emerging instrumentation, namely technology which allows mass spectrometers to be used for on-line monitoring of fluid streams. A summary of recent improvements in the performance of the rapidly developing quadrupole ion trap instrument illustrates this stage of instrument development. Improvements in resolution and mass range and their application to the characterization of biomolecules are described. The interaction of theory with experiment is illustrated through the role of simulations of ion motion in the ion trap. It is emphasized that mature instruments play a

  8. 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.

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

    NASA Technical Reports Server (NTRS)

    Parker, Ron; Carr, Zak; MacLean, Mathew; 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.

  10. Advances in Diode-Laser-Based Water Vapor Differential Absorption Lidar

    NASA Astrophysics Data System (ADS)

    Spuler, Scott; Repasky, Kevin; Morley, Bruce; Moen, Drew; Weckwerth, Tammy; Hayman, Matt; Nehrir, Amin

    2016-06-01

    An advanced diode-laser-based water vapor differential absorption lidar (WV-DIAL) has been developed. The next generation design was built on the success of previous diode-laser-based prototypes and enables accurate measurement of water vapor closer to the ground surface, in rapidly changing atmospheric conditions, and in daytime cloudy conditions up to cloud base. The lidar provides up to 1 min resolution, 150 m range resolved measurements of water vapor in a broad range of atmospheric conditions. A description of the instrument and results from its initial field test in 2014 are discussed.

  11. The GRANIT spectrometer

    SciTech Connect

    Baessler, Stefan; Beau, M; Kreuz, Michael; Nesvizhevsky, V.; Kurlov, V; Pignol, G; Protasov, K.; Vezzu, Francis; Voronin, Vladimir

    2011-01-01

    The existence of quantum states of matter in a gravitational field was demonstrated recently in the Institut Laue-Langevin (ILL), Grenoble, in a series of experiments with ultra cold neutrons (UCN). UCN in low quantum states is an excellent probe for fundamental physics, in particular for constraining extra short-range forces; as well as a tool in quantum optics and surface physics. The GRANIT is a follow-up project based on a second-generation spectrometer with ultra-high energy resolution, permanently installed in ILL. It has been constructed in framework of an ANR grant; and will become operational in 2011.

  12. Probabilistic modeling of percutaneous absorption for risk-based exposure assessments and transdermal drug delivery.

    SciTech Connect

    Ho, Clifford Kuofei

    2004-06-01

    Chemical transport through human skin can play a significant role in human exposure to toxic chemicals in the workplace, as well as to chemical/biological warfare agents in the battlefield. The viability of transdermal drug delivery also relies on chemical transport processes through the skin. Models of percutaneous absorption are needed for risk-based exposure assessments and drug-delivery analyses, but previous mechanistic models have been largely deterministic. A probabilistic, transient, three-phase model of percutaneous absorption of chemicals has been developed to assess the relative importance of uncertain parameters and processes that may be important to risk-based assessments. Penetration routes through the skin that were modeled include the following: (1) intercellular diffusion through the multiphase stratum corneum; (2) aqueous-phase diffusion through sweat ducts; and (3) oil-phase diffusion through hair follicles. Uncertainty distributions were developed for the model parameters, and a Monte Carlo analysis was performed to simulate probability distributions of mass fluxes through each of the routes. Sensitivity analyses using stepwise linear regression were also performed to identify model parameters that were most important to the simulated mass fluxes at different times. This probabilistic analysis of percutaneous absorption (PAPA) method has been developed to improve risk-based exposure assessments and transdermal drug-delivery analyses, where parameters and processes can be highly uncertain.

  13. A mechanism-based approach for absorption modeling: the Gastro-Intestinal Transit Time (GITT) model.

    PubMed

    Hénin, Emilie; Bergstrand, Martin; Standing, Joseph F; Karlsson, Mats O

    2012-06-01

    Absorption models used in the estimation of pharmacokinetic drug characteristics from plasma concentration data are generally empirical and simple, utilizing no prior information on gastro-intestinal (GI) transit patterns. Our aim was to develop and evaluate an estimation strategy based on a mechanism-based model for drug absorption, which takes into account the tablet movement through the GI transit. This work is an extension of a previous model utilizing tablet movement characteristics derived from magnetic marker monitoring (MMM) and pharmacokinetic data. The new approach, which replaces MMM data with a GI transit model, was evaluated in data sets where MMM data were available (felodipine) or not available (diclofenac). Pharmacokinetic profiles in both datasets were well described by the model according to goodness-of-fit plots. Visual predictive checks showed the model to give superior simulation properties compared with a standard empirical approach (first-order absorption rate + lag-time). This model represents a step towards an integrated mechanism-based NLME model, where the use of physiological knowledge and in vitro–in vivo correlation helps fully characterize PK and generate hypotheses for new formulations or specific populations.

  14. A digitizer based compact digital spectrometer for ion beam analysis using field programmable gate arrays and various energy algorithms

    SciTech Connect

    Jäger, Markus; Reinert, Tilo

    2013-08-15

    We report on the implementation of a compact multi-detector fully digital spectrometer and data acquisition system at a nuclear microprobe for ion beam analysis and imaging. The spectrometer design allows for system scalability with no restriction on the number of detectors. It consists of four-channel high-speed digitizer modules for detector signal acquisition and one low-speed digital-to-analog converter (DAC) module with two DAC channels and additional general purpose inputs/outputs to control ion beam scanning and data acquisition. Each digitizer module of the spectrometer provides its own Field Programmable Gate Array (FPGA) as digital signal processing unit to analyze detector signals as well as to synchronize the ion beam position in hard real-time. With the customized FPGA designs for all modules, all calculation intensive tasks are executed inside the modules, which reduces significantly the data stream to and CPU load on the control computer. To achieve an optimal energy resolution for all detector/preamplifier pulse shape characteristics, a user-definable infinite impulse response filter with high throughput for energy determination was implemented. The new spectrometer has an online data analysis feature, a compact size, and is able to process any type of detector signals such as particle induced x-ray emission, Rutherford backscattering spectrometry, or scanning transmission ion microscopy.

  15. A digitizer based compact digital spectrometer for ion beam analysis using Field Programmable Gate Arrays and various energy algorithms.

    PubMed

    Jäger, Markus; Reinert, Tilo

    2013-08-01

    We report on the implementation of a compact multi-detector fully digital spectrometer and data acquisition system at a nuclear microprobe for ion beam analysis and imaging. The spectrometer design allows for system scalability with no restriction on the number of detectors. It consists of four-channel high-speed digitizer modules for detector signal acquisition and one low-speed digital-to-analog converter (DAC) module with two DAC channels and additional general purpose inputs∕outputs to control ion beam scanning and data acquisition. Each digitizer module of the spectrometer provides its own Field Programmable Gate Array (FPGA) as digital signal processing unit to analyze detector signals as well as to synchronize the ion beam position in hard real-time. With the customized FPGA designs for all modules, all calculation intensive tasks are executed inside the modules, which reduces significantly the data stream to and CPU load on the control computer. To achieve an optimal energy resolution for all detector∕preamplifier pulse shape characteristics, a user-definable infinite impulse response filter with high throughput for energy determination was implemented. The new spectrometer has an online data analysis feature, a compact size, and is able to process any type of detector signals such as particle induced x-ray emission, Rutherford backscattering spectrometry, or scanning transmission ion microscopy.

  16. 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.

  17. Retrieval of vertical trace gas profiles from ground-based infrared absorption spectra inside and outside the Antarctic vortex using SFIT2

    NASA Astrophysics Data System (ADS)

    Wood, S. W.; Jones, N. B.; Rinsland, C. P.; Goldman, A.; Connor, B. J.; Stephen, T. M.; Lawrence, B. N.; Murcray, F. J.

    2001-05-01

    SFIT2 has been developed by NIWA, NASA Langley and the University of Denver for the retrieval of vertical trace-gas profiles from high-resolution ground-based infrared absorption spectra measured with Fourier transform spectrometers. Such measurements are made at a number of sites around the world as part of the Network for the Detection of Stratospheric Change (NDSC). The vertical profile information in the measurement is due to the pressure broadening of atmospheric absorption lines in the spectra. The retrieval method is optimal estimation, which uses information from the measurement and supplied a priori information to construct an optimal solution based on the assumed uncertainties of these two information sources. We have used SFIT2 to analyse high spectral resolution (0.0035 cm-1) infrared solar absorption spectra recorded at Arrival Heights in Antarctica (78o S), from shortly after sunrise (day 240) to the end of the year in 1999. The motion of the Antarctic vortex, and the chemical processes within it, cause large changes in the vertical profiles of most of the trace gases measured over the site. We have made use of analyses of scaled potential vorticity (sPV) from UKMO data to classify measurements as inside or outside the vortex. This information has been incorporated into the selection of a priori profile information for the analyses of a number of trace gases that are chemically active or act as tracers, including O3, HNO3, N2O, CH4, HCl and ClONO2. The retrieved mixing ratios of these gases in the lower stratosphere show that the station sampled primarily vortex air during the spring period while the vortex existed, but had brief periods outside the vortex near day 290 and again close to vortex breakdown. Comparison with independent measurements, such as the sPV calculations, satellite temperature measurements and correlative TOMS total ozone measurements, are consistent with these retrievals.

  18. Solar-absorption measurements of ozone from two ground based FTIR sites

    NASA Astrophysics Data System (ADS)

    Plaza, Eddy; Stremme, Wolfgang; Bezanilla, Alejandro; Grutter, Michel; Blumenstock, Thomas; Hase, Frank; Gisi, Michael

    2013-04-01

    Ozone reduces the amount of ultraviolet light entering earths atmosphere and continuous monitoring of total ozone column especially in higher latitudes has been a major task since the discovery of the stratospheric ozone depletion. As tropospheric ozone is a main greenhouse gas, monitoring of ozone in the lower atmosphere and also in the tropics gains importance. Tropospheric ozone also plays an important role in air quality and high levels of ozone in the boundary layer affects the public health. Ozone is produced through a complicated path of photochemistry processes from volatile organic compounds and nitrogen oxides (NOx)[1]. In large cities, these ozone precursors are mainly emitted from anthropogenic activities and in Mexico City the ozone concentration frequently exceedes the local standard for air quality (e.g. on 80% of the days of the year 2002)[2]. Since May 2012 high resolution Fourier transform infrared solar absorption spectra have been used for determining the total column and profile of ozone at the high altitude remote site Altzomoni (19°.12`N, 98°.65`E) located 60 km southeast of Mexico City at 4000 m a.s.l. These measurements are complemented with solar absorption spectra recorded with a moderate resolution FTIR spectrometer at the UNAM campus in Mexcio City (19°25`N, 99°10`W, 2240 m a.s.l.). The vertical profiles and total columns of ozone are inferred from solar spectra by using the retrieval code PROFFIT. The results are compared with simulations of the Whole Atmosphere Community Climate Model (WACCM) and other correlative data. The ozone column amount in the polluted mixing layer of Mexico City is estimated from the intercomparison of measurements at the urban and remote sites and discussed. [1] Tie, X.; Brasseur, G.; Ying, Z. Impact of Model Resolution on Chemical Ozone Formation in Mexico City: Application of the Wrf-Chem Model. Atmospheric Chemistry and Physics. 2010, 10, 8983-8995. [2] McKinley, G.; Zuk, M.; Hojer, M.; Avalos, M

  19. Is There a Common Correction for Biases in Historic Filter-Based Aerosol Absorption Measurements?

    NASA Astrophysics Data System (ADS)

    McComiskey, A. C.; Jefferson, A.; Dubey, M. K.; Aiken, A. C.; Fast, J. D.; Flynn, C. J.; Kassianov, E.

    2014-12-01

    Improved characterization of aerosol absorption is a pressing need for improving estimates of climate forcing by aerosols. Measurements of aerosol absorption are difficult to make with the accuracy and precision demanded by climate science. While several different approaches have been employed and new techniques have emerged, none can yet be considered a true 'gold standard'. Instruments that use filter-based methods have been the most widely used and are the basis of historic records. However, several studies using direct photoacoustic techniques have shown that filter-based measurements can be biased relative to these direct measurements. It has been demonstrated that this bias depends strongly on aerosol chemical composition, specifically concentration of organic mass. The wealth of information in the extensive set of historical filter-based data demands that this bias be diagnosed and corrected. A correction is critical for proper evaluation and development of chemical transport models, improved retrievals from remote sensing measurements, and integrating aerosol absorption surface and sub-orbital in situ measurements with knowledge gained from these other approaches. We have performed an intercomparison of absorption coefficients from a photoacoustic and two filter-based instruments with co-located organic mass concentrations from continuous, half-hourly averaged measurements over six months at a remote, continental site in the US (ARM SGP). The results show a bias in the filter-based measurements with organic concentration that is consistent with previous studies. Previous results come from controlled lab studies or field campaigns where absorption coefficients and organic concentrations are high and may represent aerosol close to the source. The current study is important in that these quantities are much lower and the aerosol likely more aged, representing a larger portion of the global conditions, yet shows a similar bias. This site provides other measures

  20. Structural color printing based on plasmonic metasurfaces of perfect light absorption

    SciTech Connect

    Cheng, Fei; Gao, Jie; Luk, Ting S.; Yang, Xiaodong

    2015-06-05

    Subwavelength structural color filtering and printing technologies employing plasmonic nanostructures have recently been recognized as an important and beneficial complement to the traditional colorant-based pigmentation. However, the color saturation, brightness and incident angle tolerance of structural color printing need to be improved to meet the application requirement. Here we demonstrate a structural color printing method based on plasmonic metasurfaces of perfect light absorption to improve color performances such as saturation and brightness. Thin-layer perfect absorbers with periodic hole arrays are designed at visible frequencies and the absorption peaks are tuned by simply adjusting the hole size and periodicity. Near perfect light absorption with high quality factors are obtained to realize high-resolution, angle-insensitive plasmonic color printing with high color saturation and brightness. Moreover, the fabricated metasurfaces can be protected with a protective coating for ambient use without degrading performances. The demonstrated structural color printing platform offers great potential for applications ranging from security marking to information storage.

  1. Structural color printing based on plasmonic metasurfaces of perfect light absorption

    PubMed Central

    Cheng, Fei; Gao, Jie; Luk, Ting S.; Yang, Xiaodong

    2015-01-01

    Subwavelength structural color filtering and printing technologies employing plasmonic nanostructures have recently been recognized as an important and beneficial complement to the traditional colorant-based pigmentation. However, the color saturation, brightness and incident angle tolerance of structural color printing need to be improved to meet the application requirement. Here we demonstrate a structural color printing method based on plasmonic metasurfaces of perfect light absorption to improve color performances such as saturation and brightness. Thin-layer perfect absorbers with periodic hole arrays are designed at visible frequencies and the absorption peaks are tuned by simply adjusting the hole size and periodicity. Near perfect light absorption with high quality factors are obtained to realize high-resolution, angle-insensitive plasmonic color printing with high color saturation and brightness. Moreover, the fabricated metasurfaces can be protected with a protective coating for ambient use without degrading performances. The demonstrated structural color printing platform offers great potential for applications ranging from security marking to information storage. PMID:26047486

  2. Structural color printing based on plasmonic metasurfaces of perfect light absorption

    DOE PAGES

    Cheng, Fei; Gao, Jie; Luk, Ting S.; ...

    2015-06-05

    Subwavelength structural color filtering and printing technologies employing plasmonic nanostructures have recently been recognized as an important and beneficial complement to the traditional colorant-based pigmentation. However, the color saturation, brightness and incident angle tolerance of structural color printing need to be improved to meet the application requirement. Here we demonstrate a structural color printing method based on plasmonic metasurfaces of perfect light absorption to improve color performances such as saturation and brightness. Thin-layer perfect absorbers with periodic hole arrays are designed at visible frequencies and the absorption peaks are tuned by simply adjusting the hole size and periodicity. Near perfectmore » light absorption with high quality factors are obtained to realize high-resolution, angle-insensitive plasmonic color printing with high color saturation and brightness. Moreover, the fabricated metasurfaces can be protected with a protective coating for ambient use without degrading performances. The demonstrated structural color printing platform offers great potential for applications ranging from security marking to information storage.« less

  3. [The development of acetylene on-line monitoring technology based on laser absorption spectrum].

    PubMed

    He, Ying; Zhang, Yu-jun; Kan, Rui-feng; Xia, Hui; Wang, Min; Cui, Xiao-juan; Chen, Jiu-ying; Chen, Dong; Liu, Wen-qing; Liu, Jian-guo

    2008-10-01

    As one of the materials in organic chemical industry, acetylene has been used in many aspects of chemical industry. But acetylene is a very dangerous inflammable and explosive gas, so it needs in-situ monitoring during industrial storage and production. Tunable diode laser absorption spectroscopy (TDLAS) technology has been widely used in atmospheric trace gases detection, because it has a lot of advantageous characteristics, such as high sensitivity, good selectivity, and rapid time response. The distribution characteristics of absorption lines of acetylene in near infrared band were studied, and then the system designing scheme of acetylene on-line monitoring based on near infrared tunable diode laser absorption spectroscopy technology was discussed in detail. Moreover, the system of experiment measurement was set up and the method of signal detection and the algorithm of concentration inversion were studied. In addition, the sample cell with a path length of 10 cm, and the acetylene of different known concentrations were measured. As a result, the detection limit obtained reached 1.46 cm3 x m(-3). Finally the dynamic detection experiment was carried out, and the measurement result is stable and reliable, so the design of the system is practicable through experiment analysis. On-line acetylene leakage monitoring system was developed based on the experiment, and it is suitable for giving a leakage alarm of acetylene during its storage, transportation and use.

  4. Structural color printing based on plasmonic metasurfaces of perfect light absorption.

    PubMed

    Cheng, Fei; Gao, Jie; Luk, Ting S; Yang, Xiaodong

    2015-06-05

    Subwavelength structural color filtering and printing technologies employing plasmonic nanostructures have recently been recognized as an important and beneficial complement to the traditional colorant-based pigmentation. However, the color saturation, brightness and incident angle tolerance of structural color printing need to be improved to meet the application requirement. Here we demonstrate a structural color printing method based on plasmonic metasurfaces of perfect light absorption to improve color performances such as saturation and brightness. Thin-layer perfect absorbers with periodic hole arrays are designed at visible frequencies and the absorption peaks are tuned by simply adjusting the hole size and periodicity. Near perfect light absorption with high quality factors are obtained to realize high-resolution, angle-insensitive plasmonic color printing with high color saturation and brightness. Moreover, the fabricated metasurfaces can be protected with a protective coating for ambient use without degrading performances. The demonstrated structural color printing platform offers great potential for applications ranging from security marking to information storage.

  5. Structural color printing based on plasmonic metasurfaces of perfect light absorption

    NASA Astrophysics Data System (ADS)

    Cheng, Fei; Gao, Jie; Luk, Ting S.; Yang, Xiaodong

    2015-06-01

    Subwavelength structural color filtering and printing technologies employing plasmonic nanostructures have recently been recognized as an important and beneficial complement to the traditional colorant-based pigmentation. However, the color saturation, brightness and incident angle tolerance of structural color printing need to be improved to meet the application requirement. Here we demonstrate a structural color printing method based on plasmonic metasurfaces of perfect light absorption to improve color performances such as saturation and brightness. Thin-layer perfect absorbers with periodic hole arrays are designed at visible frequencies and the absorption peaks are tuned by simply adjusting the hole size and periodicity. Near perfect light absorption with high quality factors are obtained to realize high-resolution, angle-insensitive plasmonic color printing with high color saturation and brightness. Moreover, the fabricated metasurfaces can be protected with a protective coating for ambient use without degrading performances. The demonstrated structural color printing platform offers great potential for applications ranging from security marking to information storage.

  6. [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.

  7. Nanograting-based compact VUV spectrometer and beam profiler for in-situ characterization of high-order harmonic generation light sources

    SciTech Connect

    Kornilov, Oleg; Wilcox, Russell; Gessner, Oliver

    2010-07-09

    A compact, versatile device for VUV beam characterization is presented. It combines the functionalities of a VUV spectrometer and a VUV beam profiler in one unit and is entirely supported by a standard DN200 CF flange. The spectrometer employs a silicon nitride transmission nanograting in combination with a micro-channel plate based imaging detector. This enables the simultaneous recording of wavelengths ranging from 10 nm to 80 nm with a resolution of 0.25 nm to 0.13 nm. Spatial beam profiles with diameters up to 10 mm are imaged with 0.1 mm resolution. The setup is equipped with an in-vacuum translation stage that allows for in situ switching between the spectrometer and beam profiler modes and for moving the setup out of the beam. The simple, robust design of the device is well suited for non-intrusive routine characterization of emerging laboratory- and accelerator-based VUV light sources. Operation of the device is demonstrated by characterizing the output of a femtosecond high-order harmonic generation light source.

  8. Absorption and scattering properties of carbon nanohorn-based nanofluids for direct sunlight absorbers

    PubMed Central

    2011-01-01

    In the present work, we investigated the scattering and spectrally resolved absorption properties of nanofluids consisting in aqueous and glycol suspensions of single-wall carbon nanohorns. The characteristics of these nanofluids were evaluated in view of their use as sunlight absorber fluids in a solar device. The observed nanoparticle-induced differences in optical properties appeared promising, leading to a considerably higher sunlight absorption with respect to the pure base fluids. Scattered light was found to be not more than about 5% with respect to the total attenuation of light. Both these effects, together with the possible chemical functionalization of carbon nanohorns, make this new kind of nanofluids very interesting for increasing the overall efficiency of the sunlight exploiting device. PACS 78.40.Ri, 78.35.+c, 78.67.Bf, 88.40.fh, 88.40.fr, 81.05.U. PMID:21711795

  9. Near-Infrared Light Absorption and Scattering Based on a Mono-Layer of Gold Nanoparticles

    NASA Astrophysics Data System (ADS)

    Soltanmoradi, R.; Wang, Q.; Qiu, M.; Popov, S.; Yan, M.

    2015-06-01

    We report fabrication and characterization of large-area ultrathin near-infrared light absorbers and scatterers based on a mono-layer of gold nanoparticles laying on top of a dielectric spacer and an aluminum reflector. The nanoparticles are formed through thermal annealing of an evaporated continuous gold film. Through optimization of initial gold-film thickness, spacer thickness, as well as annealing temperature we obtained samples that exhibit very low (~2%) broadband specular reflectance at near-infrared (NIR) wavelength range. By considering also diffuse reflection, we identify that the low specular reflectance can be due to either relatively high light absorption (~70%) or high light scattering (over 60%), with the latter achieved for samples having relatively sparse gold nanoparticles. Both strong absorption and scattering of NIR light are not inherent properties of the bulk materials used for fabricating the samples. Such composite optical surfaces can potentially be integrated to solar-energy harvesting and LED devices.

  10. 420nm alkali blue laser based on two-photon absorption

    NASA Astrophysics Data System (ADS)

    Tan, Yan-nan; Li, Yi-min; Liu, Tong; Gong, Fa-quan; Jia, Chun-yan; Hu, Shu; Gai, Bao-dong; Guo, Jing-wei; Liu, Wan-fa

    2015-02-01

    Based on two-photon absorption, a 420nm blue laser of alkali Rb vapor was demonstrated, and a dye laser was used as the pumping laser. Utilizing the energy level structure of Rb atom, lasering mechanism and two-photon absorption process are analyzed. Absorbing two 778.1nm photons, Rb atoms were excited from 52 S1/2 to 52 D5/2, then relaxed to 62 P3/2 with mid infrared photon radiation. 420nm blue laser was achieved by the transition 62 P3/2-->52 S1/2. To improve efficiency of the blue laser, two-photon resonant excitation pumped alkali vapor blue lasers are proposed, which will be good beam quality, high efficiency and scalable blue lasers. The development of diode pumped alkali vapor blue laser is expected.

  11. A colorimetric and absorption ratiometric anion sensor based on indole & hydrazide binding units

    NASA Astrophysics Data System (ADS)

    Zou, Linbo; Yan, Boren; Pan, Dingwu; Tan, Zan; Bao, Xiaoping

    2015-09-01

    A colorimetric and absorption ratiometric anion sensor (L) based on indole and hydrazide binding units was designed and synthesized, and its recognition & sensing properties towards different anions were studied by naked-eye observations, UV-vis and 1H NMR titration spectra. Sensor L could selectively recognize biologically important F-, AcO- and H2PO4- in DMSO over other anions, along with a significant change in its color and absorption spectrum, resulting from the formation of corresponding 1:2 (L/F-) and 1:1 (L/AcO- and L/H2PO4-) complexes. The 1H NMR titration experiments proved that sensor L experienced deprotonation of NH fragment and produced [HF2]- species, whereas a stable H-bonding complex was formed in the presence of AcO- and H2PO4-.

  12. A colorimetric and absorption ratiometric anion sensor based on indole & hydrazide binding units.

    PubMed

    Zou, Linbo; Yan, Boren; Pan, Dingwu; Tan, Zan; Bao, Xiaoping

    2015-09-05

    A colorimetric and absorption ratiometric anion sensor (L) based on indole and hydrazide binding units was designed and synthesized, and its recognition & sensing properties towards different anions were studied by naked-eye observations, UV-vis and (1)H NMR titration spectra. Sensor L could selectively recognize biologically important F(-), AcO(-) and H2PO4(-) in DMSO over other anions, along with a significant change in its color and absorption spectrum, resulting from the formation of corresponding 1:2 (L/F(-)) and 1:1 (L/AcO(-) and L/H2PO4(-)) complexes. The (1)H NMR titration experiments proved that sensor L experienced deprotonation of NH fragment and produced [HF2](-) species, whereas a stable H-bonding complex was formed in the presence of AcO(-) and H2PO4(-).

  13. Molecular detection with terahertz waves based on absorption-induced transparency metamaterials

    NASA Astrophysics Data System (ADS)

    G. Rodrigo, Sergio; Martín-Moreno, L.

    2016-10-01

    A system for the detection of spectral signatures of chemical compounds at the Terahertz regime is presented. The system consists on a holey metal film whereby the presence of a given substance provokes the appearance of spectral features in transmission and reflection induced by the molecular specimen. These induced effects can be regarded as an extraordinary optical transmission phenomenon called absorption-induced transparency (AIT). The phenomenon consist precisely in the appearance of peaks in transmission and dips in reflection after sputtering of a chemical compound onto an initially opaque holey metal film. The spectral signatures due to AIT occur unexpectedly close to the absorption energies of the molecules. The presence of a target, a chemical compound, would be thus revealed as a strong drop in reflectivity measurements. We theoretically predict the AIT based system would serve to detect amounts of hydrocyanic acid (HCN) at low rate concentrations.

  14. [A new retrieval method for ozone concentration at the troposphere based on differential absorption lidar].

    PubMed

    Fan, Guang-Qiang; Liu, Jian-Guo; Liu, Wen-Qing; Lu, Yi-Huai; Zhang, Tian-Shu; Dong, Yun-Sheng; Zhao, Xue-Song

    2012-12-01

    Aerosols interfere with differential absorption lidar ozone concentration measurement and can introduce significant errors. A new retrieval method was introduced, and ozone concentration and aerosol extinction coefficient were gained simultaneously based on the retrieval method. The variables were analyzed by experiment including aerosol lidar ratio, aerosol wavelength exponent, and aerosol-molecular ratio at the reference point. The results show that these parameters introduce error less than 8% below 1 km. The measurement error derives chiefly from signal noise and the parameters introduce error less than 3% above 1 km. Finally the vertical profile of tropospheric ozone concentration and aerosol extinction coefficient were derived by using this algorithm. The retrieval results of the algorithm and traditional dual-wavelength difference algorithm are compared and analyzed. Experimental results indicate that the algorithm is feasible, and the algorithm can reduce differential absorption lidar measurement error introduced by aerosol.

  15. An absorption mechanism and polarity-induced viscosity model for CO2 capture using hydroxypyridine-based ionic liquids.

    PubMed

    An, Xiaowei; Du, Xiao; Duan, Donghong; Shi, Lijuan; Hao, Xiaogang; Lu, Houfang; Guan, Guoqing; Peng, Changjun

    2017-01-04

    A series of new hydroxypyridine-based ionic liquids (ILs) are synthesized and applied in CO2 capture through chemical absorption, in which one IL, i.e., tetrabutylphosphonium 2-hydroxypyridine ([P4444][2-Op]), shows a viscosity as low as 193 cP with an absorption capacity as high as 1.20 mol CO2 per mol IL. Because the traditional anion-CO2 absorption mechanism cannot provide an explanation for the influences of cations and temperature on CO2 absorption capacity, herein, a novel cation-participating absorption mechanism based on the proton transfer is proposed to explain the high absorption capacity and the existence of a turning point of absorption capacity with the increase of temperature for the capture of CO2 using [P4444][n-Op] (n = 2, 3, 4) ILs. Also, the relationship between the viscosity of ILs and the linear interaction energy is proposed for the first time, which can guide how to design and synthesize ILs with low viscosity. Quantum chemistry calculations, which are based on the comprehensive analysis of dipole moment, cation-anion interaction energy and surface electrostatic potential, indicate that the different viscosities of hydroxypyridine-based ILs and the changes after CO2 absorption mainly resulted from the different distribution of negative charges in the anion.

  16. A von Hamos x-ray spectrometer based on a segmented-type diffraction crystal for single-shot x-ray emission spectroscopy and time-resolved resonant inelastic x-ray scattering studies.

    PubMed

    Szlachetko, J; Nachtegaal, M; de Boni, E; Willimann, M; Safonova, O; Sa, J; Smolentsev, G; Szlachetko, M; van Bokhoven, J A; Dousse, J-Cl; Hoszowska, J; Kayser, Y; Jagodzinski, P; Bergamaschi, A; Schmitt, B; David, C; Lücke, A

    2012-10-01

    We report on the design and performance of a wavelength-dispersive type spectrometer based on the von Hamos geometry. The spectrometer is equipped with a segmented-type crystal for x-ray diffraction and provides an energy resolution in the order of 0.25 eV and 1 eV over an energy range of 8000 eV-9600 eV. The use of a segmented crystal results in a simple and straightforward crystal preparation that allows to preserve the spectrometer resolution and spectrometer efficiency. Application of the spectrometer for time-resolved resonant inelastic x-ray scattering and single-shot x-ray emission spectroscopy is demonstrated.

  17. Development of a mechanistically based computer simulation of nitrogen oxide absorption in packed towers

    SciTech Connect

    Counce, R.M.

    1981-01-01

    A computer simulation for nitrogen oxide (NO/sub x/) scrubbing in packed towers was developed for use in process design and process control. This simulation implements a mechanistically based mathematical model, which was formulated from (1) an exhaustive literature review; (2) previous NO/sub x/ scrubbing experience with sieve-plate towers; and (3) comparisons of sequential sets of experiments. Nitrogen oxide scrubbing is characterized by simultaneous absorption and desorption phenomena: the model development is based on experiments designed to feature these two phenomena. The model was then successfully tested in experiments designed to put it in jeopardy.

  18. Modular multichannel surface plasmon spectrometer

    NASA Astrophysics Data System (ADS)

    Neuert, G.; Kufer, S.; Benoit, M.; Gaub, H. E.

    2005-05-01

    We have developed a modular multichannel surface plasmon resonance (SPR) spectrometer on the basis of a commercially available hybrid sensor chip. Due to its modularity this inexpensive and easy to use setup can readily be adapted to different experimental environments. High temperature stability is achieved through efficient thermal coupling of individual SPR units. With standard systems the performance of the multichannel instrument was evaluated. The absorption kinetics of a cysteamine monolayer, as well as the concentration dependence of the specific receptor-ligand interaction between biotin and streptavidin was measured.

  19. Determination of absorption cross-section of Si nanocrystals by two independent methods based on either absorption or luminescence

    SciTech Connect

    Valenta, J. Greben, M.; Remeš, Z.; Gutsch, S.; Hiller, D.; Zacharias, M.

    2016-01-11

    Absorption cross-section (ACS) of silicon nanocrystals (SiNCs) is determined via two completely independent approaches: (i) Excitation-intensity-dependent photoluminescence (PL) kinetics under modulated (long square pulses) pumping and (ii) absorbance measured by the photothermal deflection spectroscopy combined with morphology information obtained by the high-resolution transmission electron microscopy. This unique comparison reveals consistent ACS values around 10{sup −15} cm{sup 2} for violet excitation of SiNCs of about 3–5 nm in diameter and this value is comparable to most of direct band-gap semiconductor nanocrystals; however, it decreases steeply towards longer wavelengths. Moreover, we analyze the PL-modulation technique in detail and propose an improved experimental procedure which enables simpler implementation of this method to determine ACS of various (nano)materials in both solid and liquid states.

  20. Imaging Spectrometer for NEO Mission: Seta Instrument

    NASA Astrophysics Data System (ADS)

    de Sanctis, Maria Cristina; Filacchione, Gianrico; Capaccioni, Fabrizio; Ammannito, Eleonora; Capria, Maria Teresa; Coradini, Angioletta; Migliorini, Alessandra

    NASA, ESA and JAXA have proposed NEO Sample Return Missions to a Near Earth Object. With these missions we will have the opportunity to return for study in Earth-based laboratories a direct sample of the earliest record of how our solar system formed. The landing site and sample selection will be the most important scientific decision to make during the course of the mission. For this reason, powerful on-board remote sensing science instruments are needed to support the selection. Among these instruments, the imaging spectrometer is a key instrument, being capable to: • Characterize the mineralogical composition of the entire object; • Analyze the of the landing site and the returned sample in its own native environment; • Establish the broadest possible scientific context for the target objects within our current understanding of the solar system. Scientific Objectives: Aim of SETA experiment is to perform imaging spectroscopy in the spectral range 400-3300 nm for a complete mapping of the target with a spectral sampling of at least 20 nm and a spatial resolution of the order of meters. SETA shall be able to return a detailed determination of the mineralogical composition for the different geologic units as well as the overall surface mineralogy with a spatial resolution of the order of few meters. These compositional characterizations involve the analysis of spectral parameters that are diagnostic of the presence and composition of various mineral species and materials that may be present on the target body. Most of the interesting minerals have electronic and vibrational absorption features in their VIS-NIR reflectance spectra. Identification of these related mineral phases requires a moderate spectral resolution. The presence of organic materials may be more difficult to identify. The SETA design is based on a pushbroom imaging spectrometer operating in the 400-3300 nm range, using a 2D array HgCdTe detector. This kind of instrument allows a simultaneous

  1. CAN GROUND-BASED TELESCOPES DETECT THE OXYGEN 1.27 {mu}m ABSORPTION FEATURE AS A BIOMARKER IN EXOPLANETS?

    SciTech Connect

    Kawahara, Hajime; Matsuo, Taro; Takami, Michihiro; Fujii, Yuka; Kotani, Takayuki; Tamura, Motohide; Murakami, Naoshi; Guyon, Olivier

    2012-10-10

    The oxygen absorption line imprinted in the scattered light from Earth-like planets has been considered the most promising metabolic biomarker for exolife. We examine the feasibility of the detection of the 1.27 {mu}m oxygen band from habitable exoplanets, in particular, around late-type stars observed with a future instrument on a 30 m class ground-based telescope. We analyzed the night airglow around 1.27 {mu}m with the IRCS/echelle spectrometer on Subaru and found that the strong telluric emission from atmospheric oxygen molecules declines by an order of magnitude by midnight. By compiling nearby star catalogs combined with the sky background model, we estimate the detectability of the oxygen absorption band from an Earth twin, if it exists, around nearby stars. We find that the most dominant source of photon noise for the oxygen 1.27 {mu}m band detection comes from the night airglow if the contribution of the stellar point-spread function (PSF) halo is suppressed enough to detect the planet. We conclude that the future detectors, for which the detection contrast is limited by photon noise, can detect the oxygen 1.27 {mu}m absorption band of Earth twins for {approx}50 candidates of the late-type star. This paper demonstrates the importance of deploying a small inner working angle as an efficient coronagraph and extreme adaptive optics on extremely large telescopes, and clearly shows that doing so will enable the study of potentially habitable planets.

  2. Characteristics and error estimation of stratospheric ozone and ozone-related species over Poker Flat (65° N, 147° W), Alaska observed by a ground-based FTIR spectrometer from 2001 to 2003

    NASA Astrophysics Data System (ADS)

    Kagawa, A.; Kasai, Y.; Jones, N. B.; Yamamori, M.; Seki, K.; Murcray, F.; Murayama, Y.; Mizutani, K.; Itabe, T.

    2007-07-01

    It is important to obtain the year-to-year trend of stratospheric minor species in the context of global changes. An important example is the trend in global ozone depletion. The purpose of this paper is to report the accuracy and precision of measurements of stratospheric chemical species that are made at our Poker Flat site in Alaska (65° N, 147° W). Since 1999, minor atmospheric molecules have been observed using a Fourier-Transform solar-absorption infrared Spectrometer (FTS) at Poker Flat. Vertical profiles of the abundances of ozone, HNO3, HCl, and HF for the period from 2001 to 2003 were retrieved from FTS spectra using Rodgers' formulation of the Optimal Estimation Method (OEM). The accuracy and precision of the retrievals were estimated by formal error analysis. Errors for the total column were estimated to be 5.3%, 3.4%, 5.9%, and 5.3% for ozone, HNO3, HCl, and HF, respectively. The ozone vertical profiles were in good agreement with profiles derived from collocated ozonesonde measurements that were smoothed with averaging kernel functions that had been obtained with the retrieval procedure used in the analysis of spectra from the ground-based FTS (gb-FTS). The O3, HCl, and HF columns that were retrieved from the FTS measurements were consistent with Earth Probe/Total Ozone Mapping Spectrometer (TOMS) and HALogen Occultation Experiment (HALOE) data over Alaska within the error limits of all the respective datasets. This is the first report from the Poker Flat FTS observation site on a number of stratospheric gas profiles including a comprehensive error analysis.

  3. A global thermospheric model based on mass spectrometer and incoherent scatter data MSIS. I - N2 density and temperature

    NASA Technical Reports Server (NTRS)

    Hedin, A. E.; Reber, C. A.; Newton, G. P.; Spencer, N. W.; Salah, J. E.; Evans, J. V.; Kayser, D. C.; Alcayde, D.; Bauer, P.; Cogger, L.

    1977-01-01

    Measurements of neutral nitrogen density from mass spectrometers on five satellites (AE-B, Ogo 6, San Marco 3, Aeros A, and AE-C) and neutral temperatures inferred from incoherent scatter measurements at four ground stations are combined to produce a model of thermospheric neutral temperatures and nitrogen densities similar to the Ogo 6 empirical model (Hedin et al., 1974). This global model is designated MSIS (mass spectrometer and incoherent scatter). The global average temperature, the annual temperature variation, lower bound density, and lower bound temperature are discussed. The data set covers the time period from the end of 1965 to mid-1975 and also a wide range of solar activities. Diurnal and semidiurnal variations in lower bound density and temperature are considered, as is magnetic activity.

  4. Optical absorption enhancement of hybrid-plasmonic-based metal-semiconductor-metal photodetector incorporating metal nanogratings and embedded metal nanoparticles.

    PubMed

    Tan, Chee Leong; Karar, Ayman; Alameh, Kamal; Lee, Yong Tak

    2013-01-28

    We propose and numerically demonstrate a high absorption hybrid-plasmonic-based metal semiconductor metal photodetector (MSM-PD) comprising metal nanogratings, a subwavelength slit and amorphous silicon or germanium embedded metal nanoparticles (NPs). Simulation results show that by optimizing the metal nanograting parameters, the subwavelength slit and the embedded metal NPs, a 1.3 order of magnitude increase in electric field is attained, leading to 28-fold absorption enhancement, in comparison with conventional MSM-PD structures. This is 3.5 times better than the absorption of surface plasmon polariton (SPP) based MSM-PD structures employing metal nanogratings and a subwavelength slit. This absorption enhancement is due to the ability of the embedded metal NPs to enhance their optical absorption and scattering properties through light-stimulated resonance aided by the conduction electrons of the NPs.

  5. A Programmable Control Unit for a Balloon-Borne Mass Spectrometer Based on Intel 8085A Microprocessor,

    DTIC Science & Technology

    1979-09-07

    his initial suggestions of the system, and Ralzaundas Sukys of Northeastern University for his advice and help with the hardware portion of the thesis...October 1978 F19628-78-C-0218 18 September 1978 through present Sukys , R. and Goldberg, S. (1974),"Control Circuits for a Rocket Payload Neutralization...the Project EXCEDE: SWIR Experiment," AFGL-TR-76-200. Rochefort, J. S. and Sukys , R. (1976), "Instrumentation Systems for Mass Spectrometers", AFGL-TR

  6. External-cavity diode laser spectrometer for measuring the concentration ratio 13CO2/12CO2 by absorption in the range of 1.6 μm

    NASA Astrophysics Data System (ADS)

    Zaytsev, A. A.; Nikolaev, I. V.; Ochkin, V. N.; Tskhai, S. N.

    2015-07-01

    The method for determining the carbon isotopic ratio from CO2 absorption spectra in the optical cavity containing atmospheric air with the natural contents of carbon dioxide ~0.03% is described. The measurements are performed at atmospheric pressure in the conditions of overlapping absorption lines. The measurement accuracy is 0.3‰.

  7. Self-calibration wavelength modulation spectroscopy for acetylene detection based on tunable diode laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Huang, Qin-Bin; Xu, Xue-Mei; Li, Chen-Jing; Ding, Yi-Peng; Cao, Can; Yin, Lin-Zi; Ding, Jia-Feng

    2016-11-01

    The expressions of the second harmonic (2f) signal are derived on the basis of absorption spectral and lock-in theories. A parametric study indicates that the phase shift between the intensity and wavelength modulation makes a great contribution to the 2f signal. A self-calibration wavelength modulation spectroscopy (WMS) method based on tunable diode laser absorption spectroscopy (TDLAS) is applied, combining the advantages of ambient pressure, temperature suppression, and phase-shift influences elimination. Species concentration is retrieved simultaneously from selected 2f signal pairs of measured and reference WMS-2f spectra. The absorption line of acetylene (C2H2) at 1530.36 nm near-infrared is selected to detect C2H2 concentrations in the range of 0-400 ppmv. System sensitivity, detection precision and limit are markedly improved, demonstrating that the self-calibration method has better detecting performance than the conventional WMS. Project supported by the National Natural Science Foundation of China (Grant Nos. 61172047, 61502538, and 61501525).

  8. A novel RF-based propagation model with tissue absorption for location of the GI tract.

    PubMed

    Wang, Lujia; Liu, Li; Hu, Chao; Meng, Max Q

    2010-01-01

    In order to accurately estimate (build) the radio signal propagation attenuation model, especially inside the gastro-intestine (GI) tract of the human body, the Radio Frequency (RF) absorption characterization in human body is investigated. This characterization provides a criterion to design the Received Signal Strength (RSS) based localization system for the objective inside the human body. In this paper, the Specific Absorption Rate (SAR), E-field, H-field of the near and far field are investigated at frequencies of 434MHz, 868MHz, 1.2GHz and 2.4GHz respectively. Then, the numerical electromagnetic analysis with the finite-differencetime-domain (FDTD) is applied to model the in vivo radio propagation channels by using a dipole antenna. Finally, simulation experiments are carried out in homogenous and heterogeneous mediums. The results show that the electromagnetic (EM) propagation is not only distance and orientation dependent, but also tissue absorption dependent in human body. The proposed model is in agreement with measurements in the simulation experiments.

  9. A comparative study of LaBr3(Ce3+) and CeBr3 based gamma-ray spectrometers for planetary remote sensing applications

    NASA Astrophysics Data System (ADS)

    Kozyrev, A.; Mitrofanov, I.; Owens, A.; Quarati, F.; Benkhoff, J.; Bakhtin, B.; Fedosov, F.; Golovin, D.; Litvak, M.; Malakhov, A.; Mokrousov, M.; Nuzhdin, I.; Sanin, A.; Tretyakov, V.; Vostrukhin, A.; Timoshenko, G.; Shvetsov, V.; Granja, C.; Slavicek, T.; Pospisil, S.

    2016-08-01

    The recent availability of large volume cerium bromide crystals raises the possibility of substantially improving gamma-ray spectrometer limiting flux sensitivities over current systems based on the lanthanum tri-halides, e.g., lanthanum bromide and lanthanum chloride, especially for remote sensing, low-level counting applications or any type of measurement characterized by poor signal to noise ratios. The Russian Space Research Institute has developed and manufactured a highly sensitive gamma-ray spectrometer for remote sensing observations of the planet Mercury from the Mercury Polar Orbiter (MPO), which forms part of ESA's BepiColombo mission. The Flight Model (FM) gamma-ray spectrometer is based on a 3-in. single crystal of LaBr3(Ce3+) produced in a separate crystal development programme specifically for this mission. During the spectrometers development, manufacturing, and qualification phases, large crystals of CeBr3 became available in a subsequent phase of the same crystal development programme. Consequently, the Flight Spare Model (FSM) gamma-ray spectrometer was retrofitted with a 3-in. CeBr3 crystal and qualified for space. Except for the crystals, the two systems are essentially identical. In this paper, we report on a comparative assessment of the two systems, in terms of their respective spectral properties, as well as their suitability for use in planetary mission with respect to radiation tolerance and their propensity for activation. We also contrast their performance with a Ge detector representative of that flown on MESSENGER and show that: (a) both LaBr3(Ce3+) and CeBr3 provide superior detection systems over HPGe in the context of minimally resourced spacecraft and (b) CeBr3 is a more attractive system than LaBr3(Ce3+) in terms of sensitivities at lower gamma fluxes. Based on the tests, the FM has now been replaced by the FSM on the BepiColombo spacecraft. Thus, CeBr3 now forms the central gamma-ray detection element on the MPO spacecraft.

  10. A comparative study of LaBr3(Ce(3+)) and CeBr3 based gamma-ray spectrometers for planetary remote sensing applications.

    PubMed

    Kozyrev, A; Mitrofanov, I; Owens, A; Quarati, F; Benkhoff, J; Bakhtin, B; Fedosov, F; Golovin, D; Litvak, M; Malakhov, A; Mokrousov, M; Nuzhdin, I; Sanin, A; Tretyakov, V; Vostrukhin, A; Timoshenko, G; Shvetsov, V; Granja, C; Slavicek, T; Pospisil, S

    2016-08-01

    The recent availability of large volume cerium bromide crystals raises the possibility of substantially improving gamma-ray spectrometer limiting flux sensitivities over current systems based on the lanthanum tri-halides, e.g., lanthanum bromide and lanthanum chloride, especially for remote sensing, low-level counting applications or any type of measurement characterized by poor signal to noise ratios. The Russian Space Research Institute has developed and manufactured a highly sensitive gamma-ray spectrometer for remote sensing observations of the planet Mercury from the Mercury Polar Orbiter (MPO), which forms part of ESA's BepiColombo mission. The Flight Model (FM) gamma-ray spectrometer is based on a 3-in. single crystal of LaBr3(Ce(3+)) produced in a separate crystal development programme specifically for this mission. During the spectrometers development, manufacturing, and qualification phases, large crystals of CeBr3 became available in a subsequent phase of the same crystal development programme. Consequently, the Flight Spare Model (FSM) gamma-ray spectrometer was retrofitted with a 3-in. CeBr3 crystal and qualified for space. Except for the crystals, the two systems are essentially identical. In this paper, we report on a comparative assessment of the two systems, in terms of their respective spectral properties, as well as their suitability for use in planetary mission with respect to radiation tolerance and their propensity for activation. We also contrast their performance with a Ge detector representative of that flown on MESSENGER and show that: (a) both LaBr3(Ce(3+)) and CeBr3 provide superior detection systems over HPGe in the context of minimally resourced spacecraft and (b) CeBr3 is a more attractive system than LaBr3(Ce(3+)) in terms of sensitivities at lower gamma fluxes. Based on the tests, the FM has now been replaced by the FSM on the BepiColombo spacecraft. Thus, CeBr3 now forms the central gamma-ray detection element on the MPO spacecraft.

  11. Detection of cw-related species in complex aerosol particles deposited on surfaces with an ion trap-based aerosol mass spectrometer

    SciTech Connect

    Harris, William A; Reilly, Pete; Whitten, William B

    2007-01-01

    A new type of aerosol mass spectrometer was developed by minimal modification of an existing commercial ion trap to analyze the semivolatile components of aerosols in real time. An aerodynamic lens-based inlet system created a well-collimated particle beam that impacted into the heated ionization volume of the commercial ion trap mass spectrometer. The semivolatile components of the aerosols were thermally vaporized and ionized by electron impact or chemical ionization in the source. The nascent ions were extracted and injected into the ion trap for mass analysis. The utility of this instrument was demonstrated by identifying semivolatile analytes in complex aerosols. This study is part of an ongoing effort to develop methods for identifying chemical species related to CW agent exposure. Our efforts focused on detection of CW-related species doped on omnipresent aerosols such as house dust particles vacuumed from various surfaces found in any office building. The doped aerosols were sampled directly into the inlet of our mass spectrometer from the vacuumed particle stream. The semivolatile analytes were deposited on house dust and identified by positive ion chemical ionization mass spectrometry up to 2.5 h after deposition. Our results suggest that the observed semivolatile species may have been chemisorbed on some of the particle surfaces in submonolayer concentrations and may remain hours after deposition. This research suggests that identification of trace CW agent-related species should be feasible by this technique.

  12. Feasibility study of a novel pressure recovery system for CO2-COIL based on chemical absorption

    NASA Astrophysics Data System (ADS)

    Li, Qingwei; Jin, Yuqi; Geng, Zicai; Li, Yongzhao; Zhang, Yuelong; Sang, Fengting

    2015-02-01

    A chemical oxygen-iodine laser (COIL) is an electronic transition, low pressure, high throughput system. The use of this laser demands a suitable pressure recovery system. This paper proposed a novel pressure recovery system based on chemical absorption and the feasibility for COIL with CO2 as buffer gas (CO2-COIL) was investigated. The novel pressure recovery system works by chemisorbing the CO2-COIL effluents into two fixed-beds maintained at initial temperature of around 293-323K. Compared with the cryosorption system for N2-COIL based on physical absorption, the novel chemisorptions based pressure recovery system has a simpler logistics and a shorter run-to-run preparation time. Two kinds of solid chemo-sorbents were designed and synthesized. One was used for chemisorbing the oxidizing gases such as O2 ,Cl2 and I2, another was used for chemisorbing the acidic gas such as CO2. The capacities of the two sorbents were measured to be 3.12 mmol(O2)/g and 3.84 mmol (CO2) /g, respectively. It indicated that the synthesized sorbents could effectively chemosorb the CO2-COIL effluents. Secondly, analog test equipment was set up and used to study the feasibility of the novel pressure recovery system used for CO2-COIL. The test results showed that the novel pressure recovery system could maintain the pressure under 6 Torr for tens seconds under the continuous gas flow. It showed that the novel pressure recovery system for CO2-COIL based on chemical absorption is feasible.

  13. Total zinc absorption in young women, but not fractional zinc absorption, differs between vegetarian and meat-based diets with equal phytic acid content.

    PubMed

    Kristensen, Mette Bach; Hels, Ole; Morberg, Catrine M; Marving, Jens; Bügel, Susanne; Tetens, Inge

    2006-05-01

    Zn bioavailability is often lower in vegetarian diets mainly due to low Zn and high phytic acid contents. The objective of the present study was to determine the fractional and total absorption of Zn from a vegetarian diet in comparison with meat diets with equal concentrations of phytic acid. A randomized cross-over design, comprising three whole-day diet periods of 5 d each, with a vegetarian diet or diets containing Polish-produced meat or Danish-produced meat, was conducted. Twelve healthy female subjects completed the study. All diets had a high content of phytic acid (1250 micromol/d) and in the meat diets the main meals contained 60 g pork meat. All main meals were extrinsically labelled with the radioactive isotope 65Zn and absorption of Zn was measured in a whole-body counter. The mean Zn content of the whole-day diet was: Polish meat diet 9.9 (SE 0.14) mg, Danish meat diet 9.4 (SE 0.19) mg and vegetarian diet 7.5 (SE 0.18) mg. No difference was observed in the fractional absorption of Zn (Polish meat diet: 27 (SE 1.2) %, Danish meat diet: 27 (SE 1.9) % and vegetarian diet: 23 (SE 2.6) %). A significantly lower amount of total Zn was absorbed from the vegetarian diet (mean Zn absorption of Polish meat diet: 2.7 (SE 0.12) mg/d (P<0.001), Danish meat diet: 2.6 (SE 0.17) mg/d (P=0.006) and vegetarian diet: 1.8 (SE 0.20) mg/d). In conclusion, the vegetarian diet compared with the meat-based diets resulted in lower amounts of absorbed Zn due to a higher content of Zn in the meat diets, but no difference was observed in the fractional absorption of Zn.

  14. On-chip random spectrometer

    NASA Astrophysics Data System (ADS)

    Redding, B.; Liew, S. F.; Sarma, R.; Cao, H.

    2014-05-01

    Spectrometers are widely used tools in chemical and biological sensing, material analysis, and light source characterization. The development of a high-resolution on-chip spectrometer could enable compact, low-cost spectroscopy for portable sensing as well as increasing lab-on-a-chip functionality. However, the spectral resolution of traditional grating-based spectrometers scales with the optical pathlength, which translates to the linear dimension or footprint of the system, which is limited on-chip. In this work, we utilize multiple scattering in a random photonic structure fabricated on a silicon chip to fold the optical path, making the effective pathlength much longer than the linear dimension of the system and enabling high spectral resolution with a small footprint. Of course, the random spectrometer also requires a different operating paradigm, since different wavelengths are not spatially separated by the random structure, as they would be by a grating. Instead, light transmitted through the random structure produces a wavelengthdependent speckle pattern which can be used as a fingerprint to identify the input spectra after calibration. In practice, these wavelength-dependent speckle patterns are experimentally measured and stored in a transmission matrix, which describes the spectral-to-spatial mapping of the spectrometer. After calibrating the transmission matrix, an arbitrary input spectrum can be reconstructed from its speckle pattern. We achieved sub-nm resolution with 25 nm bandwidth at a wavelength of 1500 nm using a scattering medium with largest dimension of merely 50 μm.

  15. A model for the vertical sound speed and absorption profiles in Titan's atmosphere based on Cassini-Huygens data.

    PubMed

    Petculescu, Andi; Achi, Peter

    2012-05-01

    Measurements of thermodynamic quantities in Titan's atmosphere during the descent of Huygens in 2005 are used to predict the vertical profiles for the speed and intrinsic attenuation (or absorption) of sound. The calculations are done using one author's previous model modified to accommodate non-ideal equations of state. The vertical temperature profile places the tropopause about 40 km above the surface. In the model, a binary nitrogen-methane composition is assumed for Titan's atmosphere, quantified by the methane fraction measured by the gas chromatograph/mass spectrometer (GCMS) onboard Huygens. To more accurately constrain the acoustic wave number, the variation of thermophysical properties (specific heats, viscosity, and thermal conductivity) with altitude is included via data extracted from the NIST Chemistry WebBook [URL webbook.nist.gov, National Institute of Standards and Technology Chemistry WebBook (Last accessed 10/20/2011)]. The predicted speed of sound profile fits well inside the spread of the data recorded by Huygens' active acoustic sensor. In the N(2)-dominated atmosphere, the sound waves have negligible relaxational dispersion and mostly classical (thermo-viscous) absorption. The cold and dense environment of Titan can sustain acoustic waves over large distances with relatively small transmission losses, as evidenced by the small absorption. A ray-tracing program is used to assess the bounds imposed by the zonal wind-measured by the Doppler Wind Experiment on Huygens-on long-range propagation.

  16. Portable smartphone optical fibre spectrometer

    NASA Astrophysics Data System (ADS)

    Hossain, Md. Arafat; Canning, John; Cook, Kevin; Jamalipour, Abbas

    2015-09-01

    A low cost, optical fibre based spectrometer has been developed on a smartphone platform for field-portable spectral analysis. Light of visible wavelength is collected using a multimode optical fibre and diffracted by a low cost nanoimprinted diffraction grating. A measurement range over 300 nm span (λ = 400 to 700 nm) is obtained using the smartphone CMOS chip. The spectral resolution is Δλ ~ 0.42 nm/screen pixel. A customized Android application processed the spectra on the same platform and shares with other devices. The results compare well with commercially available spectrometer.

  17. Maximizing the Impact of Physiologically Based Oral Absorption Modeling and Simulation.

    PubMed

    Chung, John I; Kelly, Ron C; Wahlstrom, Jan; Wu, Benjamin; Wu, Tian; Alvarez-Nunez, Fernando

    2017-03-01

    The challenge of bringing innovative medicines to patients in combination with intense competition within the pharmaceutical industry has induced companies to develop quality medicines more efficiently and cost-effectively. State-of-the-art approaches to advance drug development have never been so urgent. One such approach that has been gaining traction within the industry is the application of modeling and simulation. In this commentary, the benefits of physiologically based oral absorption modeling and simulation in drug development are highlighted and suggestions for maximizing its impact are provided.

  18. Operating range of a differential-absorption lidar based on a CO{sub 2} laser

    SciTech Connect

    Ivashchenko, M V; Sherstov, I V

    2000-08-31

    The echolocation range and the remote sensing of ethylene in the atmosphere are simulated for a differential-absorption lidar based on TEA CO{sub 2} lasers. The dependence of the lidar echolocation range on the energy and the peak power of probe pulses is shown to be close to logarithmic. It is demonstrated that the use of narrow-band spectral filters is justified only for low-noise detectors and viewing angles of the receiver exceeding 5 mrad. The relative measurement error of the ethylene concentration in the atmosphere is estimated for various detection modes. (laser applications and other topics in quantum electronics)

  19. Nucleon-nucleus interaction data base: Total nuclear and absorption cross sections

    NASA Astrophysics Data System (ADS)

    Wilson, J. W.; Townsend, L. W.; Buck, W. W.; Chun, S. Y.; Hong, B. S.; Lamkin, S. L.

    1988-08-01

    Neutron total cross sections are represented for Li to Pu targets at energies above 0.1 MeV and less than 100 MeV using a modified nuclear Ramsauer formalism. The formalism is derived for energies above 100 MeV by fitting theoretical cross sections. Neutron absorption cross sections are represented by analytic expressions of similar form, but shape resonance phenomena of the Ramsauer effect is not present. Elastic differential cross sections are given as a renormalized impulse approximation. These cross section data bases are useful for nucleon transport applications.

  20. A quality control technique based on UV-VIS absorption spectroscopy for tequila distillery factories

    NASA Astrophysics Data System (ADS)

    Barbosa Garcia, O.; Ramos Ortiz, G.; Maldonado, J. L.; Pichardo Molina, J.; Meneses Nava, M. A.; Landgrave, Enrique; Cervantes, M. J.

    2006-02-01

    A low cost technique based on the UV-VIS absorption spectroscopy is presented for the quality control of the spirit drink known as tequila. It is shown that such spectra offer enough information to discriminate a given spirit drink from a group of bottled commercial tequilas. The technique was applied to white tequilas. Contrary to the reference analytic methods, such as chromatography, for this technique neither special personal training nor sophisticated instrumentations is required. By using hand-held instrumentation this technique can be applied in situ during the production process.

  1. Nucleon-nucleus interaction data base: Total nuclear and absorption cross sections

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Townsend, L. W.; Buck, W. W.; Chun, S. Y.; Hong, B. S.; Lamkin, S. L.

    1988-01-01

    Neutron total cross sections are represented for Li to Pu targets at energies above 0.1 MeV and less than 100 MeV using a modified nuclear Ramsauer formalism. The formalism is derived for energies above 100 MeV by fitting theoretical cross sections. Neutron absorption cross sections are represented by analytic expressions of similar form, but shape resonance phenomena of the Ramsauer effect is not present. Elastic differential cross sections are given as a renormalized impulse approximation. These cross section data bases are useful for nucleon transport applications.

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

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

    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.

  3. Infrared absorption of methanol clusters (CH3OH)n with n = 2-6 recorded with a time-of-flight mass spectrometer using infrared depletion and vacuum-ultraviolet ionization.

    PubMed

    Han, Hui-Ling; Camacho, Cristopher; Witek, Henryk A; Lee, Yuan-Pern

    2011-04-14

    We investigated IR spectra in the CH- and OH-stretching regions of size-selected methanol clusters, (CH(3)OH)(n) with n = 2-6, in a pulsed supersonic jet by using the IR-VUV (vacuum-ultraviolet) ionization technique. VUV emission at 118 nm served as the source of ionization in a time-of-flight mass spectrometer. The tunable IR laser emission served as a source of predissociation or excitation before ionization. The variations of intensity of protonated methanol cluster ions (CH(3)OH)(n)H(+) and CH(3)OH(+) and (CH(3)OH)(2)(+) were monitored as the IR laser light was tuned across the range 2650-3750 cm(-1). Careful processing of these action spectra based on photoionization efficiencies and the production and loss of each cluster due to photodissociation yielded IR spectra of the size-selected clusters. Spectra of methanol clusters in the OH region have been extensively investigated; our results are consistent with previous reports, except that the band near 3675 cm(-1) is identified as being associated with the proton acceptor of (CH(3)OH)(2). Spectra in the CH region are new. In the region 2800-3050 cm(-1), bands near 2845, 2956, and 3007 cm(-1) for CH(3)OH split into 2823, 2849, 2934, 2955, 2984, and 3006 cm(-1) for (CH(3)OH)(2) that correspond to proton donor and proton acceptor, indicating that the methanol dimer has a preferred open-chain structure. In contrast, for (CH(3)OH)(3), the splitting diminishes and the bands near 2837, 2954, and 2987 cm(-1) become narrower, indicating a preferred cyclic structure. Anharmonic vibrational wavenumbers predicted for the methanol open-chain dimer and the cyclic trimer with the B3LYP∕VPT2∕ANO1 level of theory are consistent with experimental results. For the tetramer and pentamer, the spectral pattern similar to that of the trimer but with greater widths was observed, indicating that the most stable structures are also cyclic.

  4. Optical sensor instrumentation using absorption- and fluorescence-based capillary waveguide optrodes

    NASA Astrophysics Data System (ADS)

    Weigl, Bernhard H.; Draxler, Sonja; Kieslinger, Dietmar; Lehmann, H.; Trettnak, Wolfgang; Wolfbeis, Otto S.; Lippitsch, Max E.

    1995-09-01

    An analytical instrument comprising absorption- and fluorescence-based capillary waveguide optrodes (CWOs) is described. Glass capillaries with a chemically sensitive coating on the inner surface are used for optical chemical sensing in gaseous and liquid samples. In case of absorption-based CWOs, light from a LED is coupled into and out of the capillary under a defined angle via a rigid waveguide and an immersion coupler. The coated glass capillary forms an inhomogeneous waveguide, in which the light is guided in both the glass and the coating. The portion of the light which is absorbed in the chemically sensitive coating is proportional to a chemcial concentration or activity. This principle is demonstrated with a pCO2-sensitive inner coating. Typical relative light intensity signal changes with this type of optical interrogation are 98%, with an active capillary length of 10 mm. For fluorescence- based CWOs, the excitation light from an LED is coupled diffusely into the glass capillary and the optical sensor layer. A major portion of the excited fluorescence light is then collected within the coated capillary, and guided to the photodiode, which is located on the distal end of the capillary waveguide. Hereby, the excitation light is separated very efficiently from the fluorescent light. As an example, a CWO for pO2 is described. By applying this optical geometry, it was possible to utilize fluorescence decay time of the sensor layer as the transducer signal even when using solid state components (LEDs and photodiodes).

  5. Active feedback regulation of a Michelson interferometer to achieve zero-background absorption measurements.

    PubMed

    Lundin, Patrik; Guan, Zuguang; Svanberg, Sune

    2011-01-20

    An active phase-controlling scheme based on a proportional-integral-derivative-controlled piezoelectric transducer is presented with the purpose of stabilizing a quasi-zero-background absorption spectrometer. A fiber-based balanced Michelson interferometer is used, and absorption due to a gas sample in one of its arms results in an increased light signal to a detector, which otherwise, thanks to destructive interference, experiences a very low light level. With the presented approach, the sensitivity of already potent absorption measurement techniques, e.g., based on modulation, could be improved even further.

  6. The GRAVITY spectrometers: thermal behaviour

    NASA Astrophysics Data System (ADS)

    Wank, Imke; Straubmeier, Christian; Wiest, Michael; Yazici, Senol; Fischer, Sebastian; Eisenhauer, Frank; Perrin, Guy S.; Perraut, Karine; Brandner, Wolfgang; Amorim, Antonio; Schöller, Markus; Eckart, Andreas

    2014-07-01

    GRAVITY is a 2nd generation VLTI Instrument o which operates on 6 interferometric baselines by using all 4 Unit Telescopes. It will deliver narrow angle astrometry with 10μas accuracy at the infrared K-band. At the 1. Physikalische Institut of the University of Cologne, which is part of the international GRAVITY consortium, two spectrometers, one for the sciene object, and one for the fringe tracking object, have been designed, manufactured and tested. These spectrometers are two individual devices, each with own housing and interfaces. For a minimized thermal background, the spectrometers are actively cooled down to an operating temperature of 80K in the ambient temperature environment of the Beam Combiner Instrument (BCI) cryostat. The outer casings are mounted thermal isolated to the base plate by glass fiber reinforced plastic (GRP) stands, copper cooling structures conduct the cold inside the spectrometers where it is routed to components via Cu cooling stripes. The spectrometers are covered with shells made of multi insulation foil. There will be shown and compared 3 cooling installations: setups in the Cologne test dewar, in the BCI dewar and in a mock-up cad model. There are some striking differences between the setup in the 2 different dewars. In the Cologne Test dewar the spectrometers are connected to the coldplate (80K); a Cu cooling structure and the thermal isolating GRP stands are bolted to the coldplate. In the BCI dewer Cu cooling structure is connected to the bottom of the nitrogen tank (80K), the GRP stands are bolted to the base plate (240K). The period of time during the cooldown process will be analyzed.

  7. Identification of hydrothermal alteration assemblages using airborne imaging spectrometer data

    NASA Technical Reports Server (NTRS)

    Feldman, S. C.; Taranik, J. V.

    1986-01-01

    Airborne Imaging Spectrometer (AIS) data, field and laboratory spectra and samples for X-ray diffraction analysis were collected in argillically altered Tertiary volcanic rocks in the Hot Creek Range, Nevada. From laboratory and field spectral measurements in the 2.0 to 2.4 micron range and using a spectroradiometer with a 4 nm sampling interval, the absorption band centers for kaolinite were loacted at 2.172 and 2.215 microns, for montmorillonite at 2.214 micron and for illite at 2.205. Based on these values and the criteria for resolution and separtion of spectral features, a spectral sampling interval of less than 4 nm is necessary to separate the clays. With an AIS spectral sampling interval of 9.3 nm, a spectral matching algorithm is more effective for separating kaolinite, montmorillonite, ad illite in Hot Creek Range than using the location of absorption minima alone.

  8. Detection of nitro-based and peroxide-based explosives by fast polarity-switchable ion mobility spectrometer with ion focusing in vicinity of Faraday detector.

    PubMed

    Zhou, Qinghua; Peng, Liying; Jiang, Dandan; Wang, Xin; Wang, Haiyan; Li, Haiyang

    2015-05-29

    Ion mobility spectrometer (IMS) has been widely deployed for on-site detection of explosives. The common nitro-based explosives are usually detected by negative IMS while the emerging peroxide-based explosives are better detected by positive IMS. In this study, a fast polarity-switchable IMS was constructed to detect these two explosive species in a single measurement. As the large traditional Faraday detector would cause a trailing reactant ion peak (RIP), a Faraday detector with ion focusing in vicinity was developed by reducing the detector radius to 3.3 mm and increasing the voltage difference between aperture grid and its front guard ring to 591 V, which could remove trailing peaks from RIP without loss of signal intensity. This fast polarity-switchable IMS with ion focusing in vicinity of Faraday detector was employed to detect a mixture of 10 ng 2,4,6-trinitrotoluene (TNT) and 50 ng hexamethylene triperoxide diamine (HMTD) by polarity-switching, and the result suggested that [TNT-H](-) and [HMTD+H](+) could be detected in a single measurement. Furthermore, the removal of trailing peaks from RIP by the Faraday detector with ion focusing in vicinity also promised the accurate identification of KClO4, KNO3 and S in common inorganic explosives, whose product ion peaks were fairly adjacent to RIP.

  9. Soft and broadband infrared metamaterial absorber based on gold nanorod/liquid crystal hybrid with tunable total absorption.

    PubMed

    Su, Zhaoxian; Yin, Jianbo; Zhao, Xiaopeng

    2015-11-18

    We design a soft infrared metamaterial absorber based on gold nanorods dispersed in liquid crystal (LC) placed on a gold film and theoretically investigate its total absorption character. Because the nanorods align with the LC molecule, the gold nanorods/LC hybrid exhibits different permittivity as a function of tilt angle of LC. At a certain tilt angle, the absorber shows an omnidirectional total absorption effect. By changing the tilt angle of LC by an external electric field, the total absorption character can be adjusted. The total absorption character also depends on the concentration, geometric dimension of nanorods, and defect of nanorod arrangement in LC. When the LC contains different size of gold nanorods, a broadband absorption can be easily realized. The characteristics including flexibility, omnidirectional, broadband and tunability make the infrared metamaterial absorber possess potential use in smart metamaterial devices.

  10. Advanced cogeneration and absorption chillers potential for service to Navy bases. Final report

    SciTech Connect

    Andrews, J.W.; Butcher, T.A.; Leigh, R.W.; McDonald, R.J.; Pierce, B.L.

    1996-04-01

    The US military uses millions of Btu`s of thermal energy to heat, cool and deliver process thermal energy to buildings on military bases, much of which is transmitted through a pipeline system incorporating thousands of miles of pipe. Much of this pipeline system is in disrepair and is nearing the end of its useful life, and the boilers which supply it are old and often inefficient. In 1993, Brookhaven National Laboratory (BNL) proposed to SERDP a three-year effort to develop advanced systems of coupled diesel cogenerators and absorption chillers which would be particularly useful in providing a continuation of the services now provided by increasingly antiquated district systems. In mid-February, 1995, BNL learned that all subsequent funding for our program had been canceled. BNL staff continued to develop the Program Plan and to adhere to the requirements of the Execution Plan, but began to look for ways in which the work could be made relevant to Navy and DoD energy needs even without the extensive development plan formerly envisioned. The entire program was therefore re-oriented to look for ways in which small scale cogeneration and absorption chilling technologies, available through procurement rather than development, could provide some solutions to the problem of deteriorated district heating systems. The result is, we believe, a striking new approach to the provision of building services on military bases: in many cases, serious study should be made of the possibility that the old district heating system should be removed or abandoned, and small-scale cogenerators and absorption chillers should be installed in each building. In the remainder of this Summary, we develop the rationale behind this concept and summarize our findings concerning the conditions under which this course of action would be advisable and the economic benefits which will accrue if it is followed. The details are developed in the succeeding sections of the report.

  11. Absorption, fluorescence, and acid-base equilibria of rhodamines in micellar media of sodium dodecyl sulfate

    NASA Astrophysics Data System (ADS)

    Obukhova, Elena N.; Mchedlov-Petrossyan, Nikolay O.; Vodolazkaya, Natalya A.; Patsenker, Leonid D.; Doroshenko, Andrey O.; Marynin, Andriy I.; Krasovitskii, Boris M.

    2017-01-01

    Rhodamine dyes are widely used as molecular probes in different fields of science. The aim of this paper was to ascertain to what extent the structural peculiarities of the compounds influence their absorption, emission, and acid-base properties under unified conditions. The acid-base dissociation (HR+ ⇄ R + H+) of a series of rhodamine dyes was studied in sodium n-dodecylsulfate micellar solutions. In this media, the form R exists as a zwitterion R±. The indices of apparent ionization constants of fifteen rhodamine cations HR+ with different substituents in the xanthene moiety vary within the range of pKaapp = 5.04 to 5.53. The distinct dependence of emission of rhodamines bound to micelles on pH of bulk water opens the possibility of using them as fluorescent interfacial acid-base indicators.

  12. Three-photon absorption in optical parametric oscillators based on OP-GaAs

    NASA Astrophysics Data System (ADS)

    Heckl, Oliver H.; Bjork, Bryce J.; Winkler, Georg; Bryan Changala, P.; Spaun, Ben; Porat, Gil; Bui, Thinh Q.; Lee, Kevin F.; Jiang, Jie; Fermann, Martin E.; Schunemann, Peter G.; Ye, Jun

    2016-11-01

    We report on the first singly-resonant (SR), synchronously pumped optical parametric oscillator (OPO) based on orientation-patterned gallium arsenide (OP-GaAs). Together with a doubly resonant (DR) degenerate OPO based on the same OP-GaAs material, the output spectra cover 3 to 6 ${\\mu}$m within ~3 dB of relative power. The DR-OPO has the highest output power reported to date from a femtosecond, synchronously pumped OPO based on OP-GaAs. We discovered strong three photon absorption with a coefficient of 0.35 ${\\pm}$ 0.06 cm${^3}$/GW${^2}$ for our OP-GaAs sample, which limits the output power of these OPOs as mid-IR light sources. We present a detailed study of the three photon loss on the performance of both the SR and DR-OPOs, and compare them to those without this loss mechanism.

  13. On-Chip Micro-Electro-Mechanical System Fourier Transform Infrared (MEMS FT-IR) Spectrometer-Based Gas Sensing.

    PubMed

    Erfan, Mazen; Sabry, Yasser M; Sakr, Mohammad; Mortada, Bassem; Medhat, Mostafa; Khalil, Diaa

    2016-05-01

    In this work, we study the detection of acetylene (C2H2), carbon dioxide (CO2) and water vapor (H2O) gases in the near-infrared (NIR) range using an on-chip silicon micro-electro-mechanical system (MEMS) Fourier transform infrared (FT-IR) spectrometer in the wavelength range 1300-2500 nm (4000-7692 cm(-1)). The spectrometer core engine is a scanning Michelson interferometer micro-fabricated using a deep-etching technology producing self-aligned components. The light is free-space propagating in-plane with respect to the silicon chip substrate. The moving mirror of the interferometer is driven by a relatively large stroke electrostatic comb-drive actuator corresponding to about 30 cm(-1) resolution. Multi-mode optical fibers are used to connect light between the wideband light source, the interferometer, the 10 cm gas cell, and the optical detector. A wide dynamic range of gas concentration down to 2000 parts per million (ppm) in only 10 cm length gas cell is demonstrated. Extending the wavelength range to the mid-infrared (MIR) range up to 4200 nm (2380 cm(-1)) is also experimentally demonstrated, for the first time, using a bulk micro-machined on-chip MEMS FT-IR spectrometer. The obtained results open the door for an on-chip optical gas sensor for many applications including environmental sensing and industrial process control in the NIR/MIR spectral ranges.

  14. Lipid-based formulations and drug supersaturation: harnessing the unique benefits of the lipid digestion/absorption pathway.

    PubMed

    Williams, Hywel D; Trevaskis, Natalie L; Yeap, Yan Yan; Anby, Mette U; Pouton, Colin W; Porter, Christopher J H

    2013-12-01

    Drugs with low aqueous solubility commonly show low and erratic absorption after oral administration. Myriad approaches have therefore been developed to promote drug solubilization in the gastrointestinal (GI) fluids. Here, we offer insight into the unique manner by which lipid-based formulations (LBFs) may enhance the absorption of poorly water-soluble drugs via co-stimulation of solubilization and supersaturation. Supersaturation provides an opportunity to generate drug concentrations in the GI tract that are in excess of the equilibrium crystalline solubility and therefore higher than that achievable with traditional formulations. Incorporation of LBF into lipid digestion and absorption pathways provides multiple drivers of supersaturation generation and the potential to enhance thermodynamic activity and absorption. These drivers include 1) formulation dispersion, 2) lipid digestion, 3) interaction with bile and 4) lipid absorption. However, high supersaturation ratios may also stimulate drug precipitation and reduce exposure where re-dissolution limits absorption. The most effective formulations are likely to be those that generate moderate supersaturation and do so close to the site of absorption. LBFs are particularly well suited to these criteria since solubilization protects against high supersaturation ratios, and supersaturation initiation typically occurs in the small intestine, at the absorptive membrane.

  15. External-cavity diode laser spectrometer for measuring the concentration ratio {sup 13}CO{sub 2}/{sup 12}CO{sub 2} by absorption in the range of 1.6 μm

    SciTech Connect

    Zaytsev, A A; Nikolaev, I V; Ochkin, V N; Tskhai, S N

    2015-07-31

    The method for determining the carbon isotopic ratio from CO{sub 2} absorption spectra in the optical cavity containing atmospheric air with the natural contents of carbon dioxide ∼0.03% is described. The measurements are performed at atmospheric pressure in the conditions of overlapping absorption lines. The measurement accuracy is 0.3‰. (laser applications and other topics in quantum electronics)

  16. Feasibility of minimally-invasive fiber-based evaluation of chondrodystrophoid canine intervertebral discs by light absorption and scattering spectroscopy

    NASA Astrophysics Data System (ADS)

    Jiang, Yuanyuan; McKeirnan, Kelci; Piao, Daqing; Bartels, Kenneth E.

    2011-03-01

    Extrusion or protrusion of an intervertebral disc is a common, frequently debilitating, painful, and sometimes fatal neurologic disease in the chondrodystrophic dog (dachshund, Pekingese, etc.). A similar condition of intervertebral disc degeneration with extrusion/protrusion is also a relatively common neurologic condition in human patients. Degeneration of the relatively avascular chondrodystrophoid intervertebral disc is associated with loss of water content, increased collagen, and deposits of calcified mineral in the nucleus pulposus. Current diagnostic methods have many limitations for providing accurate information regarding disc composition in situ prior to surgical intervention. Disc composition (i.e., mineralization), can influence the type of treatment regime and potentially prognosis and recurrence rates. The objective of this study is to investigate the feasibility of using a fiber-needle spectroscopy sensor to analyze the changes of tissue compositions involved in the chondrodystrophoid condition of the canine intervertebral disc. The nucleous pulposus, in which the metaplastic process / degeneration develops, is approximately 2mm thick and 5mm in diameter in the dachshund-sized dog. It lies in the center of the disc, surrounded by the annulus fibrosis and is enclosed by cartilaginous vertebral endplates cranially and caudally. This "shallow-and-small-slab" geometry limits the configuration of a fiber probe to sense the disc tissue volume without interference from the vertebrae. A single-fiber sensor is inserted into a 20 gauge myelographic spinal needle for insertion into the disc in situ and connected via a bifurcated fiber to the light source and a spectrometer. A tungsten light source and a 940nm light-emitting-diode are combined for spectral illumination covering VIS/NIR with expected improved sensitivity to water. Analysis of the reflectance spectra is expected to provide information of scattering and absorption compositions of tissue in

  17. Environmental temperature effect on the far-infrared absorption features of aromatic-based Titan's aerosol analogs

    NASA Astrophysics Data System (ADS)

    Gautier, Thomas; Trainer, Melissa G.; Loeffler, Mark J.; Sebree, Joshua A.; Anderson, Carrie M.

    2017-01-01

    Benzene detection has been reported in Titan's atmosphere both in the stratosphere at ppb levels by remote sensing (Coustenis et al., 2007; Vinatier et al., 2007) and in the thermosphere at ppm levels by the Cassini's Ion and Neutral Mass Spectrometer (Waite et al., 2007). This detection supports the idea that aromatic and heteroaromatic reaction pathways may play an important role in Titan's atmospheric chemistry, especially in the formation of aerosols. Indeed, aromatic molecules are easily dissociated by ultraviolet radiation and can therefore contribute significantly to aerosol formation. It has been shown recently that aerosol analogs produced from a gas mixture containing a low concentration of aromatic and/or heteroaromatic molecules (benzene, naphthalene, pyridine, quinoline and isoquinoline) have spectral signatures below 500 cm-1, a first step towards reproducing the aerosol spectral features observed by Cassini's Composite InfraRed Spectrometer (CIRS) in the far infrared (Anderson and Samuelson 2011, and references therein). In this work we investigate the influence of environmental temperature on the absorption spectra of such aerosol samples, simulating the temperature range to which aerosols, once formed, are exposed during their transport through Titan's stratosphere. Our results show that environmental temperature does not have any major effect on the spectral shape of these aerosol analogs in the far-infrared, which is consistent with the CIRS observations.

  18. Sighting of el chichon sulfur dioxide clouds with the nimbus 7 total ozone mapping spectrometer.

    PubMed

    Krueger, A J

    1983-06-24

    The eruptions of El Chichón volcano on 28 March and 3 and 4 April 1982 were observed by the Nimbus 7 total ozone mapping spectrometer due to strong absorption by volcanic gases at the shortest wavelengths of the spectrometer (312.5 and 317.5 nanometers). These ultraviolet pictures permit a measurement of the volume, dispersion, and drift of volcanic gas clouds. The tropospheric clouds were rapidly dispersed in westerly winds while persistent stratospheric clouds drifted in easterly winds at speeds up to 13 meters per second. The spectral reflectance is consistent with sulfur dioxide absorption and rules out carbon disulfide as a major constituent. A preliminary estimate of the mass of sulfur dioxide deposited in the stratosphere by the large eruptions on 3 and 4 April is 3.3 x 10(6) tons. Prior estimates of volcanic cloud volume were based on extrapolation of locally measured sulfur dioxide concentrations.

  19. Sighting of El Chichon sulfur dioxide clouds with the Nimbus 7 total ozone mapping spectrometer

    NASA Technical Reports Server (NTRS)

    Krueger, A. J.

    1983-01-01

    The eruptions of El Chichon volcano on March 28 and April 3 and 4, 1982 were observed by the Nimbus 7 total ozone mapping spectrometer due to strong absorption by volcanic gases at the shortest wavelengths of the spectrometer (312.5 and 317.5 nm). These ultraviolet pictures permit a measurement of the volume, dispersion, and drift of volcanic gas clouds. The tropospheric clouds were rapidly dispersed in westerly winds while persistent stratospheric clouds drifted in easterly winds at speeds up to 13 m/sec. The spectral reflectance is consistent with sulfur dioxide absorption and rules out carbon disulfide as a major constituent. A preliminary estimate of the mass of sulfur dioxide deposited in the stratosphere by the large eruptions on April 3 and 4 is 3.3 million tons. Prior estimates of volcanic cloud volume were based on extrapolation of locally measured sulfur dioxide concentrations.

  20. Sighting of El Chichon sulfur dioxide clouds with the Nimbus 7 total ozone mapping spectrometer

    SciTech Connect

    Krueger, A.J.

    1983-06-24

    The eruptions of El Chichon volcano on 28 March and 3 and 4 April 1982 were observed by the Nimbus 7 total ozone mapping spectrometer due to strong absorption by volcanic gases at the shortest wavelengths of the spectrometer (312.5 and 317.5 nanometers). These ultraviolet pictures permit a measurement of the volume, dispersion, and drift of volcanic gas clouds. The tropospheric clouds were rapidly dispersed in westerly winds while persistent stratospheric clouds drifted in easterly winds at speeds up to 13 meters per second. The spectral reflectance is consistent with sulfur dioxide absorption and rules out carbon disulfide as a major constituent. A preliminary estimate of the mass of sulfur dioxide deposited in the stratosphere by the large eruptions on 3 and 4 April is 3.3x10/sup 6/ tons. Prior estimates of volcanic cloud volume were based on extrapolation of locally measured sulfur dioxide concentrations.

  1. Highly efficient SO₂ absorption and its subsequent utilization by weak base/polyethylene glycol binary system.

    PubMed

    Yang, Zhen-Zhen; He, Liang-Nian; Zhao, Ya-Nan; Yu, Bing

    2013-02-05

    A binary system consisting of polyethylene glycol (PEG, proton donor)/PEG-functionalized base with suitable basicity was developed for efficient gas desulfurization (GDS) and can be regarded as an alternative approach to circumvent the energy penalty problem in the GDS process. High capacity for SO(2) capture up to 4.88 mol of SO(2)/mol of base was achieved even under low partial pressure of SO(2). Furthermore, SO(2) desorption runs smoothly under mild conditions (N(2), 25 °C) and no significant drop in SO(2) absorption was observed after five-successive absorption-desorption cycles. On the other hand, the absorbed SO(2) by PEG(150)MeIm/PEG(150), being considered as the activated form of SO(2), can be directly transformed into value-added chemicals under mild conditions, thus eliminating the energy penalty for SO(2) desorption and simultaneously realizing recycle of the absorbents. Thus, this SO(2) capture and utilization (SCU) process offers an alternative way for GDS and potentially enables the SO(2) conversion from flue gas to useful chemicals as a value-added process.

  2. A simple fiber optic humidity sensor based on water-absorption characteristic of CAB

    NASA Astrophysics Data System (ADS)

    Li, Guang; Xu, Wei; Huang, Xuguang

    2015-02-01

    A simple fiber-optic relative humidity sensor based on cellulose acetate butyrate (CAB) and Fresnel reflection is proposed and investigated theoretically and experimentally. The sensing system is only composed of one light source, three optical couplers, two photo-detectors and two fiber sensing ends. The operation principle is based on relative Fresnel reflection and water-absorption characteristic of the CAB which simultaneously contains hydrophilic and hydrophobic groups. The water absorption process will lead to variation of the CAB's refractive index or permittivity. It has to be noted that the double-channel system can effectively eliminate the intensity fluctuation of the light source and the influence of the environment. In this paper, the relative humidity environments approximately ranging from 10 % to 100% are generated and measured both in the humidification and dehumidification processes, which shows a good repeatability and reveals a very good fitting feature with a high value of R2 above 0.99. It is of reflection type and can be simply extend to be a multi-point-monitoring system. The sensing system is of cost- effective, simple operation and high precision.

  3. 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.

  4. Thermoluminescence emission spectrometer.

    PubMed

    Prescott, J R; Fox, P J; Akber, R A; Jensen, H E

    1988-08-15

    A sensitive thermoluminescence (TL) emission spectrometer based on Fourier transform spectroscopy is described. It employs a modified scanning Twyman-Green interferometer with photomultiplier detection in a photon-counting mode. The etendue is 180pi mm(2), and it covers the 350-600-nm wavelength range. The output can be displayed either as a 3-D isometric plot of intensity vs temperature and wavelength, as a contour diagram, or as a conventional TL glow curve of intensity vs temperature. It is sufficiently sensitive to record thermoluminescence spectra of dosimeter phosphors and minerals for thermoluminescence dating at levels corresponding to those found during actual use as radiation monitors or in dating. Examples of actual spectra are given.

  5. Understanding of sub-band gap absorption of femtosecond-laser sulfur hyperdoped silicon using synchrotron-based techniques

    NASA Astrophysics Data System (ADS)

    Limaye, Mukta V.; Chen, S. C.; Lee, C. Y.; Chen, L. Y.; Singh, Shashi B.; Shao, Y. C.; Wang, Y. F.; Hsieh, S. H.; Hsueh, H. C.; Chiou, J. W.; Chen, C. H.; Jang, L. Y.; Cheng, C. L.; Pong, W. F.; Hu, Y. F.

    2015-06-01

    The correlation between sub-band gap absorption and the chemical states and electronic and atomic structures of S-hyperdoped Si have been extensively studied, using synchrotron-based x-ray photoelectron spectroscopy (XPS), x-ray absorption near-edge spectroscopy (XANES), extended x-ray absorption fine structure (EXAFS), valence-band photoemission spectroscopy (VB-PES) and first-principles calculation. S 2p XPS spectra reveal that the S-hyperdoped Si with the greatest (~87%) sub-band gap absorption contains the highest concentration of S2- (monosulfide) species. Annealing S-hyperdoped Si reduces the sub-band gap absorptance and the concentration of S2- species, but significantly increases the concentration of larger S clusters [polysulfides (Sn2-, n > 2)]. The Si K-edge XANES spectra show that S hyperdoping in Si increases (decreased) the occupied (unoccupied) electronic density of states at/above the conduction-band-minimum. VB-PES spectra evidently reveal that the S-dopants not only form an impurity band deep within the band gap, giving rise to the sub-band gap absorption, but also cause the insulator-to-metal transition in S-hyperdoped Si samples. Based on the experimental results and the calculations by density functional theory, the chemical state of the S species and the formation of the S-dopant states in the band gap of Si are critical in determining the sub-band gap absorptance of hyperdoped Si samples.

  6. Determination of nickel in food samples by flame atomic absorption spectroscopy after preconcentration and microextraction based ionic liquids using full factorial and central composite design.

    PubMed

    Zarei, Zohre; Shemirani, Farzaneh

    2012-12-01

    In this research, a microextraction technique based on ionic liquids (ILs) termed in situ solvent formation microextraction (ISFME) was used for determination of nickel in solutions. 1-(2-pyridylazo)-2-naphtol (PAN) was chosen as a complexing agent. After preconcentration, the settled IL-phase was dissolved in 50 μL of ethanol and aspirated into the flame atomic absorption spectrometer (FAAS) using a home-made microsample introduction system. Injection of 50 μL volumes of analyte into an air-acetylene flame provided very sensitive spike-like and reproducible signals. ISFME is based on phase separation phenomenon of ionic liquids in aqueous solutions. This method is simple and rapid for extraction and preconcentration of metal ions from food samples and can be applied for the sample solutions containing very high concentrations of salt. Furthermore, this technique is much safer in comparison with the organic solvent extraction because of using ionic liquid. The effective parameters such as amount of IL, salt effect, concentration of the chelating agent and ion pairing agent were inspected by a full factorial design to identify important parameters and their interactions. Next, a central composite design was applied to obtain optimum point of the important parameters. Under the optimum conditions, the calibration graph was linear over the range of 2 to 80 ng/mL. The limit of detection and relative standard deviation (n= 6) were 0.6 ng/mL and 2%, respectively.

  7. Caliste-SO, a CdTe based spectrometer for bright solar event observations in hard X-rays

    NASA Astrophysics Data System (ADS)

    Meuris, A.; Limousin, O.; Gevin, O.; Blondel, C.; Martignac, J.; Vassal, M.-C.; Soufflet, F.; Fiant, N.; Bednarzik, M.; Stutz, S.; Grimm, O.; Commichau, V.

    2015-07-01

    Caliste-SO is a CdTe hybrid detector designed to be used as a spectrometer for a hard X-ray Fourier telescope. The imaging technique was implemented in the Yohkoh satellite in 1991 and the RHESSI satellite in 2002 to achieve arc-second angular resolution images of solar flares with spectroscopic capabilities. The next generation of such instruments will be the Spectrometer Telescope Imaging X-rays (STIX) on-board the Solar Orbiter mission adopted by the European Space Agency in 2011 for launch in 2017. The design and performance of Caliste-SO allows both high spectral resolution and high count rate measurements from 4 to 150 keV with limited demands on spacecraft resources such as mass, power and volume (critical for interplanetary missions). The paper reports on the flight production of the Caliste-SO devices for STIX, describing the test facilities built-up in Switzerland and France. It illustrates some results obtained with the first production samples that will be mounted in the STIX engineering model.

  8. Absorption spectrum analysis based on singular value decomposition for photoisomerization and photodegradation in organic dyes

    NASA Astrophysics Data System (ADS)

    Kawabe, Yutaka; Yoshikawa, Toshio; Chida, Toshifumi; Tada, Kazuhiro; Kawamoto, Masuki; Fujihara, Takashi; Sassa, Takafumi; Tsutsumi, Naoto

    2015-10-01

    In order to analyze the spectra of inseparable chemical mixtures, many mathematical methods have been developed to decompose them into the components relevant to species from series of spectral data obtained under different conditions. We formulated a method based on singular value decomposition (SVD) of linear algebra, and applied it to two example systems of organic dyes, being successful in reproducing absorption spectra assignable to cis/trans azocarbazole dyes from the spectral data after photoisomerization and to monomer/dimer of cyanine dyes from those during photodegaradation process. For the example of photoisomerization, polymer films containing the azocarbazole dyes were prepared, which have showed updatable holographic stereogram for real images with high performance. We made continuous monitoring of absorption spectrum after optical excitation and found that their spectral shapes varied slightly after the excitation and during recovery process, of which fact suggested the contribution from a generated photoisomer. Application of the method was successful to identify two spectral components due to trans and cis forms of azocarbazoles. Temporal evolution of their weight factors suggested important roles of long lifetimed cis states in azocarbazole derivatives. We also applied the method to the photodegradation of cyanine dyes doped in DNA-lipid complexes which have shown efficient and durable optical amplification and/or lasing under optical pumping. The same SVD method was successful in the extraction of two spectral components presumably due to monomer and H-type dimer. During the photodegradation process, absorption magnitude gradually decreased due to decomposition of molecules and their decaying rates strongly depended on the spectral components, suggesting that the long persistency of the dyes in DNA-complex related to weak tendency of aggregate formation.

  9. [Measurement of atomic number of alkali vapor and pressure of buffer gas based on atomic absorption].

    PubMed

    Zheng, Hui-jie; Quan, Wei; Liu, Xiang; Chen, Yao; Lu, Ji-xi

    2015-02-01

    High sensitivitymagnetic measurementscanbe achieved by utilizing atomic spinmanipulation in the spin-exchange-relaxation-free (SERF) regime, which uses an alkali cell as a sensing element. The atomic number density of the alkali vapor and the pressure of the buffer gasare among the most important parameters of the cell andrequire accurate measurement. A method has been proposed and developedto measure the atomic number density and the pressure based on absorption spectroscopy, by sweeping the absorption line and fittingthe experiment data with a Lorentzian profile to obtainboth parameters. Due to Doppler broadening and pressure broadening, which is mainly dominated by the temperature of the cell and the pressure of buffer gas respectively, this work demonstrates a simulation of the errorbetween the peaks of the Lorentzian profile and the Voigt profile caused by bothfactors. The results indicates that the Doppler broadening contribution is insignificant with an error less than 0.015% at 313-513 K for a 4He density of 2 amg, and an error of 0.1% in the presence of 0.6-5 amg at 393 K. We conclude that the Doppler broadening could be ignored under above conditions, and that the Lorentzianprofile is suitably applied to fit the absorption spectrumobtainingboth parameters simultaneously. In addition we discuss the resolution and the instability due to thelight source, wavelength and the temperature of the cell. We find that the cell temperature, whose uncertainty is two orders of magnitude larger than the instability of the light source and the wavelength, is one of the main factors which contributes to the error.

  10. Total ozone mapping spectrometer retrievals of noon erythemal-CIE ultraviolet irradiance compared with Brewer ground-based measurements at El Arenosillo (southwestern Spain)

    NASA Astrophysics Data System (ADS)

    Antón, M.; Cachorro, V. E.; Vilaplana, J. M.; Krotkov, N. A.; Serrano, A.; Toledano, C.; de La Morena, B.; Herman, J. R.

    2007-06-01

    During the last decade, methods have been developed for estimating ultraviolet (UV) irradiance reaching the Earth's surface using satellite-measured backscattered UV radiances. The aim of this work is to compare UV products (version 8), noon erythemal Commission Internationale de l'Eclairage (CIE)-UV irradiance (and daily CIE UV doses) from NASA Total Ozone Mapping Spectrometer (TOMS), with ground-based measurements from a well-calibrated Brewer spectrophotometer. This system is installed at the ESAt-"El Arenosillo" (Huelva) station, located in southwest Spain, near the Gulf of Cadiz, an area that is exposed to terrestrial Atlantic-Mediterranean air masses, with a high frequency (about 50%) of cloud-free days. The period analyzed was from 2000 to 2004, separated into two periods, 2000-2002 and 2003-2004, for comparative analysis. The reason for the two periods is the known calibration problem of Earth Probe-TOMS that became more pronounced by the end of 2002. The calibration errors are most important in the reflectivity and Aerosol Index TOMS data. Although the comparison results are slightly better for the first period, we do not observe major discrepancies during the second period; thus both periods were combined for final conclusions. Four different atmospheric conditions are tested in order to analyze the effects of clouds and aerosols on the differences between TOMS and Brewer data: all-sky, cloud-free with any aerosols, as well as with low and high aerosol loads. In general, under all sky conditions, TOMS overestimates the noon CIE irradiance by 7.5 ± 0.7% (daily CIE doses 8.3 ± 0.6%), but the most relevant is that the bias becomes negative for high values of TOMS reflectivity (thick clouds or high cloud optical depth) with a significant noise increase. Therefore the TOMS bias is higher for cloud-free days, 11.8 ± 0.2%, increasing with the aerosol optical depth, as measured by a colocated Cimel-AERONET Sun photometer. A high correlation between TOMS and

  11. Continuous in situ measurements of volcanic gases with a diode-laser-based spectrometer: CO2 and H2O concentration and soil degassing at Vulcano (Aeolian islands: Italy)

    PubMed Central

    De Rosa, Maurizio; Gagliardi, Gianluca; Rocco, Alessandra; Somma, Renato; De Natale, Paolo; De Natale, Giuseppe

    2007-01-01

    We report on a continuous-measurement campaign carried out in Vulcano (Aeolian islands, Sicily), devoted to the simultaneous monitoring of CO2 and H2O concentrations. The measurements were performed with an absorption spectrometer based on a semiconductor laser source emitting around a 2-μm wavelength. The emitted radiation was selectively absorbed by two molecular ro-vibrational transitions specific of the investigated species. Data for CO2 and H2O concentrations, and CO2 soil diffusive flux using an accumulation chamber configuration, were collected at several interesting sampling points on the island (Porto Levante beach- PLB, Fossa Grande Crater – FOG- and Valley of Palizzi, PAL). CO2/H2O values, measured on the ground, are very similar (around 0.019 (± 0.006)) and comparable to the previous discrete detected values of 0.213 (Fumarole F5-La Fossa crater rim) and 0.012 (Fumarole VFS – Baia Levante beach) obtaid during the 1977–1993 heating phase of the crater fumaroles. In this work much more homogeneous values are found in different points of the three sites investigated. The field work, although carried out in a limited time window (25th–28th August 2004), pointed out the new apparatus is suitable for continuous gas monitoring of the two species and their ratios, which are important geochemical indicators of volcanic activity, for which other reliable continuous monitoring systems are not yet available. PMID:17448243

  12. Study of phyllosilicates and carbonates from the Capri Chasma region of Valles Marineris on Mars based on Mars Reconnaissance Orbiter-Compact Reconnaissance Imaging Spectrometer for Mars (MRO-CRISM) observations

    NASA Astrophysics Data System (ADS)

    Jain, Nirmala; Chauhan, Prakash

    2015-04-01

    Spectral reflectance data from the MRO-CRISM (Mars Reconnaissance Orbiter-Compact Reconnaissance Imaging Spectrometer for Mars) of Capri Chasma, a large canyon within Valles Marineris on Mars, have been studied. Results of this analysis reveal the presence of minerals, such as, phyllosilicates (illite, smectite (montmorillonite)) and carbonates (ankerite and manganocalcite). These minerals hint of the aqueous history of Noachian time on Mars. Phyllosilicates are products of chemical weathering of igneous rocks, whereas carbonates could have formed from local aqueous alteration of olivine and other igneous minerals. Four different locations within the Capri Chasma region were studied for spectral reflectance based mineral detection. The study area also shows the spectral signatures of iron-bearing minerals, e.g. olivine with carbonate, indicating partial weathering of parent rocks primarily rich in ferrous mineral. The present study shows that the minerals of Capri Chasma are characterized by the presence of prominent spectral absorption features at 2.31 μm, 2.33 μm, 2.22 μm, 2.48 μm and 2.52 μm wavelength regions, indicating the existence of hydrous minerals, i.e., carbonates and phyllosilicates. The occurrence of carbonates and phyllosilicates in the study area suggests the presence of alkaline environment during the period of their formation. Results of the study are important to understand the formation processes of these mineral assemblages on Mars, which may help in understanding the evolutionary history of the planet.

  13. Discriminating the Mineralogical Composition in Drill Cuttings Based on Absorption Spectra in the Terahertz Range.

    PubMed

    Miao, Xinyang; Li, Hao; Bao, Rima; Feng, Chengjing; Wu, Hang; Zhan, Honglei; Li, Yizhang; Zhao, Kun

    2017-02-01

    Understanding the geological units of a reservoir is essential to the development and management of the resource. In this paper, drill cuttings from several depths from an oilfield were studied using terahertz time domain spectroscopy (THz-TDS). Cluster analysis (CA) and principal component analysis (PCA) were employed to classify and analyze the cuttings. The cuttings were clearly classified based on CA and PCA methods, and the results were in agreement with the lithology. Moreover, calcite and dolomite have stronger absorption of a THz pulse than any other minerals, based on an analysis of the PC1 scores. Quantitative analyses of minor minerals were also realized by building a series of linear and non-linear models between contents and PC2 scores. The results prove THz technology to be a promising means for determining reservoir lithology as well as other properties, which will be a significant supplementary method in oil fields.

  14. Quantum cascade laser-based multipass absorption system for hydrogen peroxide detection

    NASA Astrophysics Data System (ADS)

    Cao, Yingchun; Sanchez, Nancy P.; Jiang, Wenzhe; Ren, Wei; Lewicki, Rafal; Jiang, Dongfang; Griffin, Robert J.; Tittel, Frank K.

    2015-01-01

    Hydrogen peroxide (H2O2) is a relevant molecular trace gas species, that is related to the oxidative capacity of the atmosphere, the production of radical species such as OH, the generation of sulfate aerosol via oxidation of S(IV) to S(VI), and the formation of acid rain. The detection of atmospheric H2O2 involves specific challenges due to its high reactivity and low concentration (ppbv to sub-ppbv level). Traditional methods for measuring atmospheric H2O2 concentration are often based on wet-chemistry methods that require a transfer from the gas- to liquid-phase for a subsequent determination by techniques such as fluorescence spectroscopy, which can lead to problems such as sampling artifacts and interference by other atmospheric constituents. A quartz-enhanced photoacoustic spectroscopy-based system for the measurement of atmospheric H2O2 with a detection limit of 75 ppb for 1-s integration time was previously reported. In this paper, an updated H2O2 detection system based on long-optical-path-length absorption spectroscopy by using a distributed feedback quantum cascade laser (DFB-QCL) will be described. A 7.73-μm CW-DFB-QCL and a thermoelectrically cooled infrared detector, optimized for a wavelength of 8 μm, are employed for theH2O2 sensor system. A commercial astigmatic Herriott multi-pass cell with an effective optical path-length of 76 m is utilized for the reported QCL multipass absorption system. Wavelength modulation spectroscopy (WMS) with second harmonic detection is used for enhancing the signal-to-noise-ratio. A minimum detection limit of 13.4 ppb is achieved with a 2 s sampling time. Based on an Allan-Werle deviation analysis the minimum detection limit can be improved to 1.5 ppb when using an averaging time of 300 s.

  15. Satellite and Ground-based Radiometers Reveal Much Lower Dust Absorption of Sunlight than Used in Climate Models

    NASA Technical Reports Server (NTRS)

    Kaufman, Y. J.; Tanre, D.; Dubovik, O.; Karnieli, A.; Remer, L. A.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    The ability of dust to absorb solar radiation and heat the atmosphere is one of the main uncertainties in climate modeling and the prediction of climate change. Dust absorption is not well known due to limitations of in situ measurements. New techniques to measure dust absorption are needed in order to assess the impact of dust on climate. Here we report two new independent remote sensing techniques that provide sensitive measurements of dust absorption. Both are based on remote sensing. One uses satellite spectral measurements, the second uses ground based sky measurements from the AERONET network. Both techniques demonstrate that Saharan dust absorption of solar radiation is several times smaller than the current international standards. Dust cooling of the earth system in the solar spectrum is therefore significantly stronger than recent calculations indicate. We shall also address the issue of the effects of dust non-sphericity on the aerosol optical properties.

  16. Comparative analyses of the ultraviolet-B flux over the continental United State based on the NASA total ozone mapping spectrometer data and USDA ground-based measurements

    NASA Astrophysics Data System (ADS)

    Gao, Zhiqiang; Gao, Wei; Chang, Ni-Bin

    2010-10-01

    In recent years, the risk of health effects caused by the increased exposure to Ultraviolet-B (UVB) due to stratospheric ozone depletion has received wide attention. In the US, there are two ways to accurately measure the UVB. They include: 1) the National Aeronautical and Space Administration (NASA) Nimbus-7 total ozone mapping spectrometer (TOMS), and 2) the United State Department of Agriculture (USDA) ground-based network. This paper compares these two sensors' data for the ultraviolet index (UVI) nationally and regionally to support possible public health, agricultural, and ecological analyses in the future. The major findings of our study are: 1) although there are discrepancies between these two data sets, the temporal correlation coefficients can be as high as 98%. 2) Both types of data sources depict the macroscopic spatial pattern of the UVI across the continental US.indicating a strong spatial correlation; 3) The two data sources are generally consistent though the UVI of the NASA TOMS data are often about 0.13-1.05 units larger than those of the USDA ground-based measurements; and 4) Varying differences can be seen between the Midwest and two coastal regions. While the level of the UVI on the west coast has shown a decreasing trend in the past few years, its counterpart on the east coast showed an opposite trend in between 2000 and 2005. It is hard to conclude that the changes are due to variations of total ozone concentrations in this study period. The USDA ground-based measurements may be better applied for time series analysis for public health, ecological, and agricultural applications due to their ability to provide intensive calibrated point measurements.

  17. TSH-Based Protocol, Tablet Instability, and Absorption Effects on L-T4 Bioequivalence

    PubMed Central

    DiStefano, Joseph J.

    2009-01-01

    Background FDA Guidance for pharmacokinetic (PK) testing of levothyroxine (L-T4) for interbrand bioequivalence has evolved recently. Concerns remain about efficacy and safety of the current protocol, based on PK analysis following supraphysiological L-T4 dosing in euthyroid volunteers, and recent recalls due to intrabrand manufacturing problems also suggest need for further refinement. We examine these interrelated issues quantitatively, using simulated what-if scenarios testing efficacy of a TSH-based protocol and tablet stability and absorption, to enhance precision of L-T4 bioequivalence methods. Methods We use an updated simulation model of human thyroid hormone regulation quantified and validated from data that span a wide range of normal and abnormal thyroid system function. Bioequivalence: We explored a TSH-based protocol, using normal replacement dosing in simulated thyroidectomized patients, switching brands after 8 weeks of full replacement dosing. We simulated effects of tablet potency differences and intestinal absorption differences on predicted plasma TSH, T4, and triiodothyronine (T3) dynamics. Stability: We simulated effects of potency decay and lot-by-lot differences in realistic scenarios, using actual tablet potency data spanning 2 years, comparing the recently reduced 95–105% FDA-approved potency range with the original 90–110% range. Results A simulated decrease as small as 10–15% in L-T4 or its absorption generated TSH concentrations outside the bioequivalence target range (0.5–2.5 mU/L TSH), whereas T3 and T4 plasma levels were maintained normal. For a 25% reduction, steady-state TSH changed 300% (from 1.5 to 6 mU/L) compared with <25% for both T4 and T3 (both within their reference ranges). Stability: TSH, T4, and T3 remained within normal ranges for most potency decay scenarios, but tablets of the same dose strength and brand were not bioequivalent between lots and between fresh and near-expired tablets. Conclusions A

  18. Particle Spectrometers for FRIB

    NASA Astrophysics Data System (ADS)

    Amthor, A. M.

    2014-09-01

    FRIB promises to dramatically expand the variety of nuclear systems available for direct experimental study by providing rates of many rare isotopes orders of magnitude higher than those currently available. A new generation of experimental systems, including new particle spectrometers will be critical to our ability to take full advantage of the scientific opportunities offered by FRIB. The High-Rigidity Spectrometer (HRS) will allow for experiments with the most neutron-rich and short-lived isotopes produced by in-flight fragmentation at FRIB. The bending capability of the HRS (8 Tm) matches to the rigidity for which rare isotopes are produced at the highest intensity in the FRIB fragment separator. The experimental program will be focused on nuclear structure and astrophysics, and allow for the use of other cutting-edge detection systems for gamma, neutron, and charged-particle detection. Stopped and reaccelerated beam studies will be an important compliment to in-flight techniques at FRIB, providing world-unique, high quality, intense rare isotope beams at low energies up to and beyond the Coulomb barrier--with the completion of ReA12--and serving many of the science goals of the broader facility, from nuclear structure and astrophysics to applications. Two specialized recoil spectrometers are being developed for studies with reaccelerated beams. SECAR, the Separator for Capture Reactions, will be built following ReA3, coupled to a windowless gas jet target, JENSA, and will focus on radiative capture reactions for astrophysics, particularly those needed to improve our understanding of novae and X-ray bursts. A recoil separator following ReA12 is proposed to address a variety of physics cases based on fusion-evaporation, Coulomb excitation, transfer, and deep-inelastic reactions by providing a large angular, momentum and charge state acceptance; a high mass resolving power; and the flexibility to couple to a variety of auxiliary detector systems. Two designs

  19. Constraints on Mercury's surface composition from MESSENGER neutron spectrometer data

    NASA Astrophysics Data System (ADS)

    Riner, M. A.; Lucey, P. G.; McCubbin, F. M.; Taylor, G. J.

    2011-08-01

    The composition of Mercury's surface is poorly known, but the MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) mission has provided a wealth of new data from three flybys. In particular, MESSENGER Neutron Spectrometer (NS) observations reveal a surface enriched in neutron absorbing elements, consistent with interpretations of color and albedo observations suggesting a surface composition enriched in Fe-Mg-Ti oxides. In this study, we have computed the neutron absorption cross sections for all of the available proposed surface compositions of Mercury and evaluated the plausibility of each surface composition based on the neutron absorption cross section observed by MESSENGER. For identified plausible compositions, the implications for the thermal and magmatic evolution of Mercury are discussed. The measured macroscopic neutron absorption cross section of Mercury is inconsistent with a crust formed from partial melting of plausible bulk mantle compositions, flotation in a magma ocean or adiabatic melting of upwelling cumulates during magma ocean overturn. However, the observed neutron absorption is consistent with model compositions of late-stage magma-ocean cumulates and some proposed compositions from spectral modeling and equilibrium modeling. This suggests that the enrichment of neutron absorbing elements may be indicative of the processes that acted to form Mercury's crust. The enrichment in neutron absorbing elements, in combination with spectral observations that constrain FeO in silicates (< 2 wt.%), offers strong evidence of a magma ocean on Mercury since global scale melting appears to be required to concentrate the major neutron absorbing elements while minimizing Fe in silicate minerals. We also find that iron plays a secondary role in the neutron absorption of plausible surface compositions and its variations within different Fe-Mg-Ti oxide solid solution series does not cause any overlap among the various oxide series in neutron

  20. NO2 measurements in Hong Kong using LED based long path differential optical absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Chan, K. L.; Pöhler, D.; Kuhlmann, G.; Hartl, A.; Platt, U.; Wenig, M. O.

    2012-05-01

    In this study we present the first long term measurements of atmospheric nitrogen dioxide (NO2) using a LED based Long Path Differential Optical Absorption Spectroscopy (LP-DOAS) instrument. This instrument is measuring continuously in Hong Kong since December 2009, first in a setup with a 550 m absorption path and then with a 3820 m path at about 30 m to 50 m above street level. The instrument is using a high power blue light LED with peak intensity at 450 nm coupled into the telescope using a Y-fibre bundle. The LP-DOAS instrument measures NO2 levels in the Kowloon Tong and Mongkok district of Hong Kong and we compare the measurement results to mixing ratios reported by monitoring stations operated by the Hong Kong Environmental Protection Department in that area. Hourly averages of coinciding measurements are in reasonable agreement (R = 0.74). Furthermore, we used the long-term data set to validate the Ozone Monitoring Instrument (OMI) NO2 data product. Monthly averaged LP-DOAS and OMI measurements correlate well (R = 0.84) when comparing the data for the OMI overpass time. We analyzed weekly patterns in both data sets and found that the LP-DOAS detects a clear weekly cycle with a reduction on weekends during rush hour peaks, whereas OMI is not able to observe this weekly cycle due to its fix overpass time (13:30-14:30 LT - local time).