WorldWideScience

Sample records for solar absorption spectroscopy

  1. Carrier Formation Dynamics in Prototypical Organic Solar Cells as Investigated by Transient Absorption Spectroscopy

    Directory of Open Access Journals (Sweden)

    Yutaka Moritomo

    2016-01-01

    Full Text Available Subpicosecond transient absorption spectroscopy is a powerful tool used to clarify the exciton and carrier dynamics within the organic solar cells (OSCs. In this review article, we introduce a method to determine the absolute numbers of the excitons and carriers against delay time (t only from the photoinduced absorption (PIA and electrochemically induced absorption (EIA spectra. Application of this method to rr-P3HT-, PTB7-, and SMDPPEH-based OSCs revealed common aspects of the carrier formation dynamics. First, the temporal evolution of the numbers of the excitons and carriers indicates that the late decay component of exciton does not contribute to the carrier formation process. This is probably because the late component has not enough excess energy to separate into the electron and hole across the donor/acceptor (D/A interface. Secondly, the spectroscopy revealed that the exciton-to-carrier conversion process is insensitive to temperature. This observation, together with the fast carrier formation time in OSCs, is consistent with the hot exciton picture.

  2. Improved Carrier Transport in Perovskite Solar Cells Probed by Femtosecond Transient Absorption Spectroscopy.

    Science.gov (United States)

    Serpetzoglou, Efthymis; Konidakis, Ioannis; Kakavelakis, George; Maksudov, Temur; Kymakis, Emmanuel; Stratakis, Emmanuel

    2017-12-20

    CH 3 NH 3 PbI 3 perovskite thin films have been deposited on glass/indium tin oxide/hole transport layer (HTL) substrates, utilizing two different materials as the HTLs. In the first configuration, the super hydrophilic polymer poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate), known as PEDOT:PSS, was employed as the HTL material, whereas in the second case, the nonwetting poly(triarylamine) semiconductor polymer, known as PTAA, was used. It was found that when PTAA is used as the HTL material, the averaged power conversion efficiency (PCE) of the perovskite solar cells (PSCs) remarkably increases from 12.60 to 15.67%. To explore the mechanism behind this enhancement, the aforementioned perovskite/HTL arrangements were investigated by time-resolved transient absorption spectroscopy (TAS) performed under inert conditions. By means of TAS, the charge transfer, carrier trapping, and hole injection dynamics from the photoexcited perovskite layers to the HTL can be directly monitored via the characteristic bleaching profile of the perovskite at ∼750 nm. TAS studies revealed faster relaxation times and decay dynamics when the PTAA polymer is employed, which potentially account for the enhanced PCE observed. The TAS results are correlated with the structure and crystalline quality of the corresponding perovskite films, investigated by scanning electron microscopy, X-ray diffraction, atomic force microscopy, micro-photoluminescence, and transmittance spectroscopy. It is concluded that TAS is a benchmark technique for the understanding of the carrier transport mechanisms in PSCs and constitutes a figure-of-merit tool toward their efficiency improvement.

  3. Analysis of the absorption layer of CIGS solar cell by laser-induced breakdown spectroscopy.

    Science.gov (United States)

    Lee, Seok H; Shim, Hee S; Kim, Chan K; Yoo, Jong H; Russo, Richard E; Jeong, Sungho

    2012-03-01

    Laser induced breakdown spectroscopy (LIBS) was applied for the elemental analysis of the thin copper indium gallium diselenide (CuIn(1-x)Ga(x)Se(2) [CIGS]) absorption layer deposited on Mo-coated soda-lime glass by the co-evaporation technique. The optimal laser and detection parameters for LIBS measurement of the CIGS absorption layer (1.23 μm) were investigated. The calibration results of Ga/In ratio with respect to the concentration ratios measured by x-ray fluorescence and inductively coupled plasma optical emission spectroscopy showed good linearity. © 2012 Optical Society of America

  4. Zeeman atomic absorption spectroscopy

    International Nuclear Information System (INIS)

    Loos-Vollebregt, M.T.C. de.

    1980-01-01

    A new method of background correction in atomic absorption spectroscopy has recently been introduced, based on the Zeeman splitting of spectral lines in a magnetic field. A theoretical analysis of the background correction capability observed in such instruments is presented. A Zeeman atomic absorption spectrometer utilizing a 50 Hz sine wave modulated magnetic field is described. (Auth.)

  5. Cationic effect on dye-sensitized solar cell properties using electrochemical impedance and transient absorption spectroscopy techniques

    Science.gov (United States)

    Gupta, Ravindra Kumar; Bedja, Idriss

    2017-06-01

    Redox-couple polymer electrolytes, (poly(ethylene oxide)-succinonitrile) blend/MI-I2, where M  =  Li or K, were prepared by the solution cast method. Owing to the plasticizing property of K+ ions, the K+ ion-based electrolyte exhibited better electrical conductivity than the Li+ ion-based electrolyte, which did however exhibit better photovoltaic properties. Electrochemical impedance spectroscopy revealed faster redox species diffusions and interfacial processes in the Li+ ion-based dye-sensitized solar cells than in the K+ ion-based ones. Transient absorption spectroscopy ascertained faster dye-regeneration by the Li+ ion-based electrolyte than the K+ ion-based electrolyte.

  6. Solar absorption surface panel

    Science.gov (United States)

    Santala, Teuvo J.

    1978-01-01

    A composite metal of aluminum and nickel is used to form an economical solar absorption surface for a collector plate wherein an intermetallic compound of the aluminum and nickel provides a surface morphology with high absorptance and relatively low infrared emittance along with good durability.

  7. Total Absorption Spectroscopy

    International Nuclear Information System (INIS)

    Rubio, B.; Gelletly, W.

    2007-01-01

    The problem of determining the distribution of beta decay strength (B(GT)) as a function of excitation energy in the daughter nucleus is discussed. Total Absorption Spectroscopy is shown to provide a way of determining the B(GT) precisely. A brief history of such measurements and a discussion of the advantages and disadvantages of this technique, is followed by examples of two recent studies using the technique. (authors)

  8. Relic Neutrino Absorption Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Eberle, b

    2004-01-28

    Resonant annihilation of extremely high-energy cosmic neutrinos on big-bang relic anti-neutrinos (and vice versa) into Z-bosons leads to sizable absorption dips in the neutrino flux to be observed at Earth. The high-energy edges of these dips are fixed, via the resonance energies, by the neutrino masses alone. Their depths are determined by the cosmic neutrino background density, by the cosmological parameters determining the expansion rate of the universe, and by the large redshift history of the cosmic neutrino sources. We investigate the possibility of determining the existence of the cosmic neutrino background within the next decade from a measurement of these absorption dips in the neutrino flux. As a by-product, we study the prospects to infer the absolute neutrino mass scale. We find that, with the presently planned neutrino detectors (ANITA, Auger, EUSO, OWL, RICE, and SalSA) operating in the relevant energy regime above 10{sup 21} eV, relic neutrino absorption spectroscopy becomes a realistic possibility. It requires, however, the existence of extremely powerful neutrino sources, which should be opaque to nucleons and high-energy photons to evade present constraints. Furthermore, the neutrino mass spectrum must be quasi-degenerate to optimize the dip, which implies m{sub {nu}} 0.1 eV for the lightest neutrino. With a second generation of neutrino detectors, these demanding requirements can be relaxed considerably.

  9. XCO2-measurements with a tabletop FTS using solar absorption spectroscopy

    Directory of Open Access Journals (Sweden)

    A. Simon

    2012-11-01

    Full Text Available A commercial low-resolution (0.5 cm−1 Fourier Transform Spectrometer (FTS has been modified and is used for determining the total column XCO2 of the atmosphere by analysing direct solar radiation. The spectrometer has a small home-built solar tracker attached, so that it is a ready-to-use instrument. The results are validated with temporally coinciding on-site measurements taken with a high-resolution Total Carbon Column Observing Network (TCCON FTIR spectrometer. For the whole comparison period of 5 months (26 measurement days an agreement with TCCON results of (0.12 ± 0.08% is achieved. This makes the spectrometer a promising candidate for a low-cost addition to the TCCON core FTIR sites, especially suitable for locations with limited infrastructure. An impressive mechanical and thermal stability is proved, enabling the spectrometer for use in field campaigns and for the monitoring of local sources.

  10. X-ray Absorption Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Yano, Junko; Yachandra, Vittal K.

    2009-07-09

    This review gives a brief description of the theory and application of X-ray absorption spectroscopy, both X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), especially, pertaining to photosynthesis. The advantages and limitations of the methods are discussed. Recent advances in extended EXAFS and polarized EXAFS using oriented membranes and single crystals are explained. Developments in theory in understanding the XANES spectra are described. The application of X-ray absorption spectroscopy to the study of the Mn4Ca cluster in Photosystem II is presented.

  11. Solar absorption cooling

    NARCIS (Netherlands)

    Kim, D.S.

    2007-01-01

    As the world concerns more and more on global climate changes and depleting energy resources, solar cooling technology receives increasing interests from the public as an environment-friendly and sustainable alternative. However, making a competitive solar cooling machine for the market still

  12. A differential optical absorption spectroscopy method for retrieval from ground-based Fourier transform spectrometers measurements of the direct solar beam

    Science.gov (United States)

    Huo, Yanfeng; Duan, Minzheng; Tian, Wenshou; Min, Qilong

    2015-08-01

    A differential optical absorption spectroscopy (DOAS)-like algorithm is developed to retrieve the column-averaged dryair mole fraction of carbon dioxide from ground-based hyper-spectral measurements of the direct solar beam. Different to the spectral fitting method, which minimizes the difference between the observed and simulated spectra, the ratios of multiple channel-pairs—one weak and one strong absorption channel—are used to retrieve from measurements of the shortwave infrared (SWIR) band. Based on sensitivity tests, a super channel-pair is carefully selected to reduce the effects of solar lines, water vapor, air temperature, pressure, instrument noise, and frequency shift on retrieval errors. The new algorithm reduces computational cost and the retrievals are less sensitive to temperature and H2O uncertainty than the spectral fitting method. Multi-day Total Carbon Column Observing Network (TCCON) measurements under clear-sky conditions at two sites (Tsukuba and Bremen) are used to derive xxxx for the algorithm evaluation and validation. The DOAS-like results agree very well with those of the TCCON algorithm after correction of an airmass-dependent bias.

  13. Remote laser evaporative molecular absorption spectroscopy

    Science.gov (United States)

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

    2016-09-01

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

  14. In situ flow cell for combined X-ray absorption spectroscopy, X-ray diffraction, and mass spectrometry at high photon energies under solar thermochemical looping conditions

    Science.gov (United States)

    Rothensteiner, Matthäus; Jenni, Joel; Emerich, Hermann; Bonk, Alexander; Vogt, Ulrich F.; van Bokhoven, Jeroen A.

    2017-08-01

    An in situ/operando flow cell for transmission mode X-ray absorption spectroscopy (XAS), X-ray diffraction (XRD), and combined XAS/XRD measurements in a single experiment under the extreme conditions of two-step solar thermochemical looping for the dissociation of water and/or carbon dioxide was developed. The apparatus exposes materials to relevant conditions of both the auto-reduction and the oxidation sub-steps of the thermochemical cycle at ambient temperature up to 1773 K and enables determination of the composition of the effluent gases by online quadrupole mass spectrometry. The cell is based on a tube-in-tube design and is heated by means of a focusing infrared furnace. It was tested successfully for carbon dioxide splitting. In combined XAS/XRD experiments with an unfocused beam, XAS measurements were performed at the Ce K edge (40.4 keV) and XRD measurements at 64.8 keV and 55.9 keV. Furthermore, XRD measurements with a focused beam at 41.5 keV were carried out. Equimolar ceria-hafnia was auto-reduced in a flow of argon and chemically reduced in a flow of hydrogen/helium. Under reducing conditions, all cerium(iv) was converted to cerium(iii) and a cation-ordered pyrochlore-type structure was formed, which was not stable upon oxidation in a flow of carbon dioxide.

  15. In situ analysis of the Zn(S,O) buffer layer preparation for chalcopyrite solar cells by Zn L-edge X-ray absorption spectroscopy.

    Science.gov (United States)

    Lauermann, Iver; Kropp, Timo; Vottier, Damien; Ennaoui, Ahmed; Eberhardt, Wolfgang; Aziz, Emad F

    2009-02-23

    Bridging the gap between high-vacuum soft X-ray absorption spectroscopy and real systems under ambient conditions probes chemical reactions in situ during deposition and annealing processes. The origin of highly efficient buffer layers in Zn(S,O) is the complex formation between Zn(2+) and the S=C group of thiourea (see schematic), which allows ligand-to-metal and metal-to-ligand charge transfer (LMCT and MLCT).

  16. Theory of attosecond absorption spectroscopy in krypton

    DEFF Research Database (Denmark)

    Baggesen, Jan Conrad; Lindroth, Eva; Madsen, Lars Bojer

    2012-01-01

    A theory for time-domain attosecond pump–attosecond probe photoabsorption spectroscopy is formulated and related to the atomic response. The theory is illustrated through a study of attosecond absorption spectroscopy in krypton. The atomic parameters entering the formulation such as energies...... of the hole in this manner. In a second example, a hole is created in an inner shell by the first pulse, and the second probe pulse couples an even more tightly bound state to that hole. The hole decays in this example by Auger electron emission, and the absorption spectroscopy follows the decay of the hole...

  17. Absorptive coating for aluminum solar panels

    Science.gov (United States)

    Desmet, D.; Jason, A.; Parr, A.

    1979-01-01

    Method for coating forming coating of copper oxide from copper component of sheet aluminum/copper alloy provides strong durable solar heat collector panels. Copper oxide coating has solar absorption characteristics similar to black chrome and is much simpler and less costly to produce.

  18. Solar heating and cooling with absorption refrigeration

    OpenAIRE

    Montlló Casabayó, Gerard

    2010-01-01

    This project is focused on solar heating and cooling installations that use solar thermal energy to produce heat for domestic hot water or space heating, and cooling for air conditioning through absorption refrigeration cycle. The first part of the project is a literature review of said technology. The main components of such installations are described and results and conclusions from existing installations are reviewed. The second part is focused on designing, modelling and simula...

  19. Aerosol optical absorption measurements with photoacoustic spectroscopy

    Science.gov (United States)

    Liu, Kun; Wang, Lei; Liu, Qiang; Wang, Guishi; Tan, Tu; Zhang, Weijun; Chen, Weidong; Gao, Xiaoming

    2015-04-01

    Many parameters related to radiative forcing in climate research are known only with large uncertainties. And one of the largest uncertainties in global radiative forcing is the contribution from aerosols. Aerosols can scatter or absorb the electromagnetic radiation, thus may have negative or positive effects on the radiative forcing of the atmosphere, respectively [1]. And the magnitude of the effect is directly related to the quantity of light absorbed by aerosols [2,3]. Thus, sensitivity and precision measurement of aerosol optical absorption is crucial for climate research. Photoacoustic spectroscopy (PAS) is commonly recognized as one of the best candidates to measure the light absorption of aerosols [4]. A PAS based sensor for aerosol optical absorption measurement was developed. A 532 nm semiconductor laser with an effective power of 160 mW was used as a light source of the PAS sensor. The PAS sensor was calibrated by using known concentration NO2. The minimum detectable optical absorption coefficient (OAC) of aerosol was determined to be 1 Mm-1. 24 hours continues measurement of OAC of aerosol in the ambient air was carried out. And a novel three wavelength PAS aerosol OAC sensor is in development for analysis of aerosol wavelength-dependent absorption Angstrom coefficient. Reference [1] U. Lohmann and J. Feichter, Global indirect aerosol effects: a review, Atmos. Chem. Phys. 5, 715-737 (2005) [2] M. Z. Jacobson, Strong radiative heating due to the mixing state of black carbon in atmospheric aerosols, Nature 409, 695-697 (2001) [3] V. Ramanathan and G. Carmichae, Global and regional climate changes due to black carbon, nature geoscience 1, 221-227 (2008) [4] W.P Arnott, H. Moosmuller, C. F. Rogers, T. Jin, and R. Bruch, Photoacoustic spectrometer for measuring light absorption by aerosol: instrument description. Atmos. Environ. 33, 2845-2852 (1999).

  20. UV laser long-path absorption spectroscopy

    Science.gov (United States)

    Dorn, Hans-Peter; Brauers, Theo; Neuroth, Rudolf

    1994-01-01

    Long path Differential Optical Absorption Spectroscopy (DOAS) using a picosecond UV laser as a light source was developed in our institute. Tropospheric OH radicals are measured by their rotational absorption lines around 308 nm. The spectra are obtained using a high resolution spectrograph. The detection system has been improved over the formerly used optomechanical scanning device by application of a photodiode array which increased the observed spectral range by a factor of 6 and which utilizes the light much more effectively leading to a considerable reduction of the measurement time. This technique provides direct measurements of OH because the signal is given by the product of the absorption coefficient and the OH concentration along the light path according to Lambert-Beers law. No calibration is needed. Since the integrated absorption coefficient is well known the accuracy of the measurement essentially depends on the extent to which the OH absorption pattern can be detected in the spectra. No interference by self generated OH radicals in the detection lightpath has been observed. The large bandwidth (greater than 0.15 nm) and the high spectral resolution (1.5 pm) allows absolute determination of interferences by other trace gas absorptions. The measurement error is directly accessible from the absorption-signal to baseline-noise ratio in the spectra. The applicability of the method strongly depends on visibility. Elevated concentrations of aerosols lead to considerable attenuation of the laser light which reduces the S/N-ratio. In the moderately polluted air of Julich, where we performed a number of OH measurement spectra. In addition absorption features of unidentified species were frequently detected. A quantitative deconvolution even of the known species is not easy to achieve and can leave residual structures in the spectra. Thus interferences usually increase the noise and deteriorate the OH detection sensitivity. Using diode arrays for sensitive

  1. Infrared absorption spectroscopy with color center lasers

    Science.gov (United States)

    Carrick, P. G.; Curl, R. F.; Tittel, F. K.; Koester, E.; Pfeiffer, J.; Kasper, J. V. V.

    Results are presented of the application of a computer controlled color center laser combined with Stark modulation and magnetic rotation effect modulation for obtaining high resolution spectra of molecular species. The lowest electronic transition of the C2H free radical, of interest in astrophysics, is observed near 3772/cm and the high resolution spectra of methanol and hydroxylamine in the OH stretching region are obtained. It is concluded that color center laser absorption spectroscopy combined with sensitivy enhancement through modulation techniques is a sensitive and versatile means of determining the spectra of free radicals and transient molecules in the infared region.

  2. Various applications of Zeeman atomic absorption spectroscopy

    International Nuclear Information System (INIS)

    Koizumi, H.

    1978-06-01

    The application of the Zeeman effect to atomic absorption spectroscopy has been studied over the past several years. This technique has a larger area of application than conventional AAS because of its high degree of selectivity. The ZAA technique can be used for organometallic species determination by interfacing with a high-pressure liquid chromatograph. Various kinds of eluents can be directly introduced in the ZAA system; even organic solvents or high-concentration salt solutions. For example, the Co atom in the functional center of Vitamin B12 molecule was separately analyzed in the presence of much larger amounts of inorganic Co. In the ZAA technique, interference caused by direct spectral overlap can also be corrected. As a typical example, the Sb line at 217.02 nm overlaps the Pb absorption line at 217.00 nm. However, 1000 ppM of Pb did not cause any interference signal in the Sb analysis by ZAA. This is especially important in the analysis of gun powder residue that is often carried out by chemists working in the forensic field. In the determination of trace elements in matrices of unknown composition, the ZAA technique achieved highly reliable results by employing the standard addition method to correct for chemical interferences, because any nonspecific absorption or emission does not give rise to interference signals with this technique

  3. Soft X-ray absorption and photoemission spectroscopy study of semiconductor oxide nanoparticles for dye-sensitized solar cell: ZnSnO3 and Zn2SnO4

    Science.gov (United States)

    Kim, Hyun Woo; Lee, Eunsook; Kim, D. H.; Seong, Seungho; Moon, Soo Yeon; Shin, Yu-Ju; Baik, J.; Shin, H. J.; Kang, J.-S.

    2016-06-01

    The electronic structures of the Zn-stannate nanoparticles of ZnSnO3 and Zn2SnO4, which are the potential nano-structured semiconductor oxides for a dye sensitized solar cell (DSSC), have been investigated by employing photoemission spectroscopy (PES) and soft X-ray absorption spectroscopy (XAS), and compared to those of reference materials. The divalent and tetravalent valence states of Zn2+ and Sn4+ ions are confirmed experimentally. The energy levels of both the valence-band and conduction-band edges are determined experimentally. The top of the valence band in PES is slightly higher in Zn2SnO4 than in ZnSnO3. The onset energies of the O 1s XAS spectra of the Zn-stannates are found to be similar to each other, but higher than that of TiO2. The O 1 s XAS spectrum of ZnSnO3 exhibits the higher unoccupied density of states near the bottom of the conduction band than those of Zn2SnO4, SnO2 and ZnO, reflecting the larger number of holes in the Zn 3 d bands of ZnSnO3. Hence, the easier electron transfer is expected from the LUMO (lowest unoccupied molecular orbital) of a dye molecule to the conduction band of ZnSnO3 nanoparticles on the transparent conductive electrode of a DSSC.

  4. Precision Saturated Absorption Spectroscopy of H3+

    Science.gov (United States)

    Guan, Yu-chan; Liao, Yi-Chieh; Chang, Yung-Hsiang; Peng, Jin-Long; Shy, Jow-Tsong

    2016-06-01

    In our previous work on the Lamb dips of the νb{2} fundamental band of H3+, the saturated absorption spectrum was obtained by the third-derivative spectroscopy using frequency modulation [1]. However, the frequency modulation also causes error in absolute frequency determination. To solve this problem, we have built an offset-locking system to lock the OPO pump frequency to an iodine-stabilized Nd:YAG laser. With this modification, we are able to scan the OPO idler frequency precisely and obtain the profile of the Lamb dips. Double modulation (amplitude modulation of the idler power and concentration modulation of the ion) is employed to subtract the interference fringes of the signal and increase the signal-to-noise ratio effectively. To Determine the absolute frequency of the idler wave, the pump wave is offset locked on the R(56) 32-0 a10 hyperfine component of 127I2, and the signal wave is locked on a GPS disciplined fiber optical frequency comb (OFC). All references and lock systems have absolute frequency accuracy better than 10 kHz. Here, we demonstrate its performance by measuring one transition of methane and sixteen transitions of H3+. This instrument could pave the way for the high-resolution spectroscopy of a variety of molecular ions. [1] H.-C. Chen, C.-Y. Hsiao, J.-L. Peng, T. Amano, and J.-T. Shy, Phys. Rev. Lett. 109, 263002 (2012).

  5. Optimization of absorption air-conditioning for solar energy applications

    Science.gov (United States)

    Perry, E. H.

    1976-01-01

    Improved performance of solar cooling systems using the lithium bromide water absorption cycle is investigated. Included are computer simulations of a solar-cooled house, analyses and measurements of heat transfer rates in absorption system components, and design and fabrication of various system components. A survey of solar collector convection suppression methods is presented.

  6. Absorption of solar radiation in broken clouds

    Energy Technology Data Exchange (ETDEWEB)

    Zuev, V.E.; Titov, G.A.; Zhuravleva, T.B. [Institute of Atmospheric Optics, Tomsk (Russian Federation)

    1996-04-01

    It is recognized now that the plane-parallel model unsatisfactorily describes the transfer of radiation through broken clouds and that, consequently, the radiation codes of general circulation models (GCMs) must be refined. However, before any refinement in a GCM code is made, it is necessary to investigate the dependence of radiative characteristics on the effects caused by the random geometry of cloud fields. Such studies for mean fluxes of downwelling and upwelling solar radiation in the visible and near-infrared (IR) spectral range were performed by Zuev et al. In this work, we investigate the mean spectral and integrated absorption of solar radiation by broken clouds (in what follows, the term {open_quotes}mean{close_quotes} will be implied but not used, for convenience). To evaluate the potential effect of stochastic geometry, we will compare the absorption by cumulus (0.5 {le} {gamma} {le} 2) to that by equivalent stratus ({gamma} <<1) clouds; here {gamma} = H/D, H is the cloud layer thickness and D the characteristic horizontal cloud size. The equivalent stratus clouds differ from cumulus only in the aspect ratio {gamma}, all the other parameters coinciding.

  7. Analysis of a solar powered absorption system

    International Nuclear Information System (INIS)

    Said, S.A.M.; El-Shaarawi, M.A.I.; Siddiqui, M.U.

    2015-01-01

    Highlights: • Conventional absorption system modified to increase COP. • Results indicated increase of 10% in COP due to dephlegmator heat recovery. • Results indicated increase of 8% in COP due to refrigerant storage unit. • Results indicated increase of 18% in COP due to combined effect of modifications. • Simulation results indicated a very good agreement with the measured results. - Abstract: Today, fossil fuel is the primary extensively used source of energy. However, its negative impact on the environment have forced the energy research continuity to seriously consider renewable sources of energy. Solar energy, in particular, has been the main focus in this regard because it is a source of clean energy and naturally available. This study presents the design and analysis of a solar powered absorption refrigeration system modified to increase its coefficient of performance (COP). The modifications include recovering of waste heat from a dephlegmator and utilization of a refrigerant storage unit. The simulation results indicate an increase of 10% in the COP of the conventional design using dephlegmator heat recovery and an increase of 8% in the COP of the conventional design due to the use of a refrigerant storage. The analysis for the combined effect of modifications indicates an increase of 18% in the COP compared to conventional design. Calculated values of coefficient of performance indicate a very good agreement with the ones obtained based on measurement

  8. Solar neutrino spectroscopy (before and after superkamiokande)

    International Nuclear Information System (INIS)

    Smirnov, A.Yu.

    1996-11-01

    Results of solar neutrino spectroscopy based on data from four experiments are presented. Perspectives related to forthcoming experiments are discussed. Implications of the results for neutrino properties are considered. (author). 54 refs, 2 tabs

  9. UV-VIS absorption spectroscopy: Lambert-Beer reloaded

    Science.gov (United States)

    Mäntele, Werner; Deniz, Erhan

    2017-02-01

    UV-VIS absorption spectroscopy is used in almost every spectroscopy laboratory for routine analysis or research. All spectroscopists rely on the Lambert-Beer Law but many of them are less aware of its limitations. This tutorial discusses typical problems in routine spectroscopy that come along with technical limitations or careless selection of experimental parameters. Simple rules are provided to avoid these problems.

  10. High durability solar absorptive coating and methods for making same

    Energy Technology Data Exchange (ETDEWEB)

    Hall, Aaron C.; Adams, David P.

    2016-11-22

    The present invention relates to solar absorptive coatings including a ceramic material. In particular, the coatings of the invention are laser-treated to further enhance the solar absorptivity of the material. Methods of making and using such materials are also described.

  11. Investigations into solar powered diffusion-absorption cooling machines

    OpenAIRE

    Jakob, Uli

    2005-01-01

    Solar thermal driven or assisted absorption cooling machines are gaining increasing importance due to the continually growing demand for airconditioning in domestic housing as well as office and hotel buildings. Presently there are no thermally driven absorption cooling machines available on the market that can provide a smaller cooling capacity than 10kW for cooling buildings. For this reason, two single-effect solar heated ammonia/water (NHJlH20) Diffusion-Absorption Co...

  12. Valence-to-core-detected X-ray absorption spectroscopy

    DEFF Research Database (Denmark)

    Hall, Eleanor R.; Pollock, Christopher J.; Bendix, Jesper

    2014-01-01

    X-ray absorption spectroscopy (XAS) can provide detailed insight into the electronic and geometric structures of transition-metal active sites in metalloproteins and chemical catalysts. However, standard XAS spectra inherently represent an average contribution from the entire coordination...

  13. X-ray absorption near-edge structure (XANES) spectroscopy

    NARCIS (Netherlands)

    Henderson, Grant S.; De Groot, Frank M F|info:eu-repo/dai/nl/08747610X; Moulton, Benjamin J A

    2014-01-01

    The previous Reviews in Mineralogy volume on spectroscopic methods (Vol. 18 Spectroscopic Methods in Mineralogy and Geology, Frank C. Hawthorne, ed. 1988), contained a single chapter on X-ray absorption spectroscopy which reviewed aspects of both EXAFS (Extended X-ray Absorption Fine Structure) and

  14. UV-VIS absorption spectroscopy: Lambert-Beer reloaded.

    Science.gov (United States)

    Mäntele, Werner; Deniz, Erhan

    2017-02-15

    UV-VIS absorption spectroscopy is used in almost every spectroscopy laboratory for routine analysis or research. All spectroscopists rely on the Lambert-Beer Law but many of them are less aware of its limitations. This tutorial discusses typical problems in routine spectroscopy that come along with technical limitations or careless selection of experimental parameters. Simple rules are provided to avoid these problems. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. X-ray absorption spectroscopy (EXAFS)

    International Nuclear Information System (INIS)

    Craievich, A.F.

    1983-01-01

    The experimental technics of Extended X-ray Absorption Fine Structure (EXAFS) is presented and several uses of it in atomic, molecular and bio physics are shown. The recent progresses of this technics, both theoretical and experimental, are discussed and the future perspectives on this subject are commented. (L.C.) [pt

  16. Absorption line spectroscopy of the interstellar medium

    International Nuclear Information System (INIS)

    Jura, M.

    1983-01-01

    Absorption line studies of the interstellar medium are described. The discussion is in three parts. The first describes current views of diffuse interstellar clouds, while the second reports the results of recent extensive surveys of interstellar regions. The final part is an outline of possible future observations. (orig.)

  17. Spectrophotometer-Integrating-Sphere System for Computing Solar Absorptance

    Science.gov (United States)

    Witte, William G., Jr.; Slemp, Wayne S.; Perry, John E., Jr.

    1991-01-01

    A commercially available ultraviolet, visible, near-infrared spectrophotometer was modified to utilize an 8-inch-diameter modified Edwards-type integrated sphere. Software was written so that the reflectance spectra could be used to obtain solar absorptance values of 1-inch-diameter specimens. A descriptions of the system, spectral reflectance, and software for calculation of solar absorptance from reflectance data are presented.

  18. Single-particle absorption spectroscopy by photothermal contrast.

    Science.gov (United States)

    Yorulmaz, Mustafa; Nizzero, Sara; Hoggard, Anneli; Wang, Lin-Yung; Cai, Yi-Yu; Su, Man-Nung; Chang, Wei-Shun; Link, Stephan

    2015-05-13

    Removing effects of sample heterogeneity through single-molecule and single-particle techniques has advanced many fields. While background free luminescence and scattering spectroscopy is widely used, recording the absorption spectrum only is rather difficult. Here we present an approach capable of recording pure absorption spectra of individual nanostructures. We demonstrate the implementation of single-particle absorption spectroscopy on strongly scattering plasmonic nanoparticles by combining photothermal microscopy with a supercontinuum laser and an innovative calibration procedure that accounts for chromatic aberrations and wavelength-dependent excitation powers. Comparison of the absorption spectra to the scattering spectra of the same individual gold nanoparticles reveals the blueshift of the absorption spectra, as predicted by Mie theory but previously not detectable in extinction measurements that measure the sum of absorption and scattering. By covering a wavelength range of 300 nm, we are furthermore able to record absorption spectra of single gold nanorods with different aspect ratios. We find that the spectral shift between absorption and scattering for the longitudinal plasmon resonance decreases as a function of nanorod aspect ratio, which is in agreement with simulations.

  19. Molecular shock response of explosives: electronic absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Mcgrne, Shawn D [Los Alamos National Laboratory; Moore, David S [Los Alamos National Laboratory; Whitley, Von H [Los Alamos National Laboratory; Bolme, Cindy A [Los Alamos National Laboratory; Eakins, Daniel E [Los Alamos National Laboratory

    2009-01-01

    Electronic absorption spectroscopy in the range 400-800 nm was coupled to ultrafast laser generated shocks to begin addressing the question of the extent to which electronic excitations are involved in shock induced reactions. Data are presented on shocked polymethylmethacrylate (PMMA) thin films and single crystal pentaerythritol tetranitrate (PETN). Shocked PMMA exhibited thin film interference effects from the shock front. Shocked PETN exhibited interference from the shock front as well as broadband increased absorption. Relation to shock initiation hypotheses and the need for time dependent absorption data (future experiments) is briefly discussed.

  20. Seasonal Solar Thermal Absorption Energy Storage Development.

    Science.gov (United States)

    Daguenet-Frick, Xavier; Gantenbein, Paul; Rommel, Mathias; Fumey, Benjamin; Weber, Robert; Gooneseker, Kanishka; Williamson, Tommy

    2015-01-01

    This article describes a thermochemical seasonal storage with emphasis on the development of a reaction zone for an absorption/desorption unit. The heat and mass exchanges are modelled and the design of a suitable reaction zone is explained. A tube bundle concept is retained for the heat and mass exchangers and the units are manufactured and commissioned. Furthermore, experimental results of both absorption and desorption processes are presented and the exchanged power is compared to the results of the simulations.

  1. Developing a Transdisciplinary Teaching Implement for Atomic Absorption Spectroscopy

    Science.gov (United States)

    Drew, John

    2008-01-01

    In this article I explain why I wrote the set of teaching notes on Atomic Absorption Spectroscopy (AAS) and why they look the way they do. The notes were intended as a student reference to question, highlight and write over as much as they wish during an initial practical demonstration of the threshold concept being introduced, in this case…

  2. Visualizing the Solute Vaporization Interference in Flame Atomic Absorption Spectroscopy

    Science.gov (United States)

    Dockery, Christopher R.; Blew, Michael J.; Goode, Scott R.

    2008-01-01

    Every day, tens of thousands of chemists use analytical atomic spectroscopy in their work, often without knowledge of possible interferences. We present a unique approach to study these interferences by using modern response surface methods to visualize an interference in which aluminum depresses the calcium atomic absorption signal. Calcium…

  3. Atomic Absorption Spectroscopy. The Present and the Future.

    Science.gov (United States)

    Slavin, Walter

    1982-01-01

    The status of current techniques and methods of atomic absorption (AA) spectroscopy (flame, hybrid, and furnace AA) is discussed, including limitations. Technological opportunities and how they may be used in AA are also discussed, focusing on automation, microprocessors, continuum AA, hybrid analyses, and others. (Author/JN)

  4. Standard Practice for Evaluating Solar Absorptive Materials for Thermal Applications

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2007-01-01

    1.1 This practice covers a testing methodology for evaluating absorptive materials used in flat plate or concentrating collectors, with concentrating ratios not to exceed five, for solar thermal applications. This practice is not intended to be used for the evaluation of absorptive surfaces that are (1) used in direct contact with, or suspended in, a heat-transfer liquid, (that is, trickle collectors, direct absorption fluids, etc.); (2) used in evacuated collectors; or (3) used in collectors without cover plate(s). 1.2 Test methods included in this practice are property measurement tests and aging tests. Property measurement tests provide for the determination of various properties of absorptive materials, for example, absorptance, emittance, and appearance. Aging tests provide for exposure of absorptive materials to environments that may induce changes in the properties of test specimens. Measuring properties before and after an aging test provides a means of determining the effect of the exposure. 1.3 Th...

  5. Broadband solar absorption enhancement via periodic nanostructuring of electrodes.

    KAUST Repository

    Adachi, Michael M

    2013-10-14

    Solution processed colloidal quantum dot (CQD) solar cells have great potential for large area low-cost photovoltaics. However, light utilization remains low mainly due to the tradeoff between small carrier transport lengths and longer infrared photon absorption lengths. Here, we demonstrate a bottom-illuminated periodic nanostructured CQD solar cell that enhances broadband absorption without compromising charge extraction efficiency of the device. We use finite difference time domain (FDTD) simulations to study the nanostructure for implementation in a realistic device and then build proof-of-concept nanostructured solar cells, which exhibit a broadband absorption enhancement over the wavelength range of λ = 600 to 1,100 nm, leading to a 31% improvement in overall short-circuit current density compared to a planar device containing an approximately equal volume of active material. Remarkably, the improved current density is achieved using a light-absorber volume less than half that typically used in the best planar devices.

  6. Self absorption in luminescent solar concentrators

    NARCIS (Netherlands)

    Krumer, Z.

    2014-01-01

    Luminescent solar concentrators are photovoltaic devices made of thin transparent material, in which luminescent particles are dispersed. The incident light enters the device through its large facets and is subsequently absorbed by the luminescent particles, which re-emit it whilst changing its

  7. Thermodynamic Analysis of the Irreversibilities in Solar Absorption Refrigerators

    Directory of Open Access Journals (Sweden)

    Emma Berrich Betouche

    2016-03-01

    Full Text Available A thermodynamic analysis of the irreversibility on solar absorption refrigerators is presented. Under the hierarchical decomposition and the hypothesis of an endoreversible model, many functional and practical domains are defined. The effect of external heat source temperature on the entropy rate and on the inverse specific cooling load (ISCL multiplied by the total area of the refrigerator A/Qe are studied. This may help a constructor to well dimension the solar machine under an optimal technico-economical criterion A/Qe and with reasonable irreversibility on the refrigerator. The solar concentrator temperature effect on the total exchanged area, on the technico-economical ratio A/Qe, and on the internal entropy rate are illustrated and discussed. The originality of these results is that they allow a conceptual study of a solar absorption refrigeration cycle.

  8. Patterning of graphite nanocones for broadband solar spectrum absorption

    Directory of Open Access Journals (Sweden)

    Yaoran Sun

    2015-06-01

    Full Text Available We experimentally demonstrate a broadband vis-NIR absorber consisting of 300-400 nm nanocone structures on highly oriented pyrolytic graphite. The nanocone structures are fabricated through simple nanoparticle lithography process and analyzed with three-dimensional finite-difference time-domain methods. The measured absorption reaches an average level of above 95% over almost the entire solar spectrum and agrees well with the simulation. Our simple process offers a promising material for solar-thermal devices.

  9. Infrared absorption spectroscopy of single particles using photophoresis

    International Nuclear Information System (INIS)

    Lin, H.

    1985-01-01

    In situ absorption spectroscopy was performed on a single suspended salt particle using photophoresis. The charged ammonium sulfate particle was levitated in an electric-quadrpole field and illuminated by a CO 2 laser. The size-dependent absorption spectrum of ammonium sulfate particles was observed for the first time to our knowledge at 930-1080 cm -1 . The effects of gas pressure and laser power were also determined. For particles approximately 10 μm in diameter, the photophoretic force was observed to be negative

  10. Artificial absorption creation for more accurate tunable diode laser absorption spectroscopy measurement

    Science.gov (United States)

    Wei, Wei; Chang, Jun; Cao, Lihua; Liu, Yuanyuan; Chen, Xi; Zhu, Cunguang; Qin, Zengguang

    2017-09-01

    A novel strategy for more accurate tunable diode laser absorption spectroscopy (TDLAS) measurement is presented. This method is immune to non-absorption transmission losses, and allows dead zone removal for ultra-low concentration detection, and reference point selection at atmospheric pressure. The method adjusts laser emission and creates artificial absorption peaks according to requirements. By creating an artificial absorption peak next to the real absorption zone, calibration is not necessary. The developed method can be applied to not only wavelength modulation spectroscopy (WMS) but also direct absorption (DA). In WMS, the method does not need two harmonic signals, resulting in higher reliability, better performance, and no electro-optical gain uncertainty. At the same time, non-absorption transmission losses effect is suppressed from 70% to 0.425% with DA and from 70% to 0.225% with WMS method. When the artificial absorption peak coincides with the real one, the dead zone of measurement can be removed to give a lower detection limit, and water vapor still can be detected when concentration is lower than 0.2 ppm in our experiment. Reference point selection uncertainty with the DA method, especially when the signal-to-noise ratio is low and absorption line is broad, can also be facilitated. And the uncertainty of reference point selection is improved from 6% to 0.8% by measuring reference point amplitude. The method is demonstrated and validated by WMS and DA measurements of water vapor (1 atm, 296 K, 1368.597 nm). The measurement results obtained using the new method reveal its promise in TDLAS.

  11. Infrared absorption spectroscopy and chemical kinetics of free radicals

    Energy Technology Data Exchange (ETDEWEB)

    Curl, R.F.; Glass, G.P. [Rice Univ., Houston, TX (United States)

    1993-12-01

    This research is directed at the detection, monitoring, and study of chemical kinetic behavior by infrared absorption spectroscopy of small free radical species thought to be important intermediates in combustion. During the last year, infrared kinetic spectroscopy using excimer laser flash photolysis and color-center laser probing has been employed to study the high resolution spectrum of HCCN, the rate constant of the reaction between ethynyl (C{sub 2}H) radical and H{sub 2} in the temperature region between 295 and 875 K, and the recombination rate of propargyl (CH{sub 2}CCH) at room temperature.

  12. An absorption-diffusion refrigerator operated by solar energy

    Energy Technology Data Exchange (ETDEWEB)

    Sabry, T.I.; Hanafy, A.E.; Klup, A.M.A. [Menoufla Univ. (Egypt)

    1993-12-31

    The design of a commercially available vapor absorption electrical refrigerator was changed to make it suitable for running on solar energy. The refrigerator was attached to a thermo-siphonic flat-plate solar oil heating system with small tank-collector volume ratio collector to supply heat to the generator of the refrigerator. The test results revealed that the minimum evaporator temperature was around 2 C. The designed solar heating system was suitable for the operation of the refrigerator by solar energy. From the analysis of the operation of the refrigerator by both electrical as well as solar energy, it was found that the ambient temperature is a dominant factor affecting the system performance. (Authors). 10 refs., 14 figs., 1 tab.

  13. Magnetic and solar effects on ionospheric absorption at high latitude

    Directory of Open Access Journals (Sweden)

    M. Pietrella

    2002-06-01

    Full Text Available Some periods of intense solar events and of strong magnetic storms have been selected and their effects on the ionospheric D region have been investigated on the basis of ionospheric absorption data derived from riometer measurements made at the Italian Antarctic Base of Terra Nova Bay (geographic coordinates: 74.69 S, 164.12 E; geomagnetic coordinates: 77.34 S, 279.41 E. It was found that sharp increases in ionospheric absorption are mainly due to solar protons emission with an energy greater than 10 MeV. Moreover, the day to night ratios of the ionospheric absorption are greater than 2 in the case of strong events of energetic protons emitted by the Sun, while during magnetic storms, these ratios range between 1 and 2.

  14. Thermal properties of carbon black aqueous nanofluids for solar absorption

    Science.gov (United States)

    Han, Dongxiao; Meng, Zhaoguo; Wu, Daxiong; Zhang, Canying; Zhu, Haitao

    2011-07-01

    In this article, carbon black nanofluids were prepared by dispersing the pretreated carbon black powder into distilled water. The size and morphology of the nanoparticles were explored. The photothermal properties, optical properties, rheological behaviors, and thermal conductivities of the nanofluids were also investigated. The results showed that the nanofluids of high-volume fraction had better photothermal properties. Both carbon black powder and nanofluids had good absorption in the whole wavelength ranging from 200 to 2,500 nm. The nanofluids exhibited a shear thinning behavior. The shear viscosity increased with the increasing volume fraction and decreased with the increasing temperature at the same shear rate. The thermal conductivity of carbon black nanofluids increased with the increase of volume fraction and temperature. Carbon black nanofluids had good absorption ability of solar energy and can effectively enhance the solar absorption efficiency.

  15. Hybrid solar concentrator with zero self-absorption loss

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Wenxuan; Wang, Tongxin; Wang, Xin; Wu, Si; Luo, Yanhua; Tian, Xiujie; Zhang, Qijin [CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Anhui Key Laboratory of Optoelectronic Science and Technology, Hefei, Anhui (China)

    2010-12-15

    The use of a luminescent solar concentrator (LSC) with a high geometric gain is one of the methods to achieve low cost of photovoltaic power. However, the self-absorption loss of the LSC is a restraining factor working against the gain. Differed from organic dyes, the hybrid dyes (rare earth complexes), composed of organic antenna and inorganic emitting ions, have very low self-absorption losses. A hybrid solar concentrator (HSC) has been fabricated by doping a rare earth complex, Eu(TTA){sub 3}Phen, into a polymer optical fiber (POF). Experiments on the HSC show that there is no self-absorption loss, and the emission photons increase linearly with geometric gain (increasing from around 50 to approximately 200). (author)

  16. Thermal properties of carbon black aqueous nanofluids for solar absorption

    Directory of Open Access Journals (Sweden)

    Han Dongxiao

    2011-01-01

    Full Text Available Abstract In this article, carbon black nanofluids were prepared by dispersing the pretreated carbon black powder into distilled water. The size and morphology of the nanoparticles were explored. The photothermal properties, optical properties, rheological behaviors, and thermal conductivities of the nanofluids were also investigated. The results showed that the nanofluids of high-volume fraction had better photothermal properties. Both carbon black powder and nanofluids had good absorption in the whole wavelength ranging from 200 to 2,500 nm. The nanofluids exhibited a shear thinning behavior. The shear viscosity increased with the increasing volume fraction and decreased with the increasing temperature at the same shear rate. The thermal conductivity of carbon black nanofluids increased with the increase of volume fraction and temperature. Carbon black nanofluids had good absorption ability of solar energy and can effectively enhance the solar absorption efficiency.

  17. Use of absorption spectroscopy for refined petroleum product discrimination

    Science.gov (United States)

    Short, Michael

    1991-07-01

    On-line discrimination between arbitrary petroleum products is necessary for optimal control of petroleum refinery and pipeline operation and process control involving petroleum distillates. There are a number of techniques by which petroleum products can be distinguished from one another. Among these, optical measurements offer fast, non-intrusive, real-time characterization. The application examined here involves optically monitoring the interface between dissimilar batches of fluids in a gasoline pipeline. After examination of near- infrared and mid-infrared absorption spectroscopy and Raman spectroscopy, Fourier transform mid-infrared (FTIR) spectroscopy was chosen as the best candidate for implementation. On- line FTIR data is presented, verifying the applicability of the technique for batch interface detection.

  18. Comparison of photoacoustic spectroscopy, conventional absorption spectroscopy, and potentiometry as probes of lanthanide speciation

    International Nuclear Information System (INIS)

    Torres, R.A.; Palmer, C.E.A.; Baisden, P.A.; Russo, R.E.; Silva, R.J.

    1990-01-01

    The authors measured the stability constants of praseodymium acetate and oxydiacetate complexes by laser-induced photoacoustic spectroscopy, conventional UV-visible absorption spectroscopy, and pH titration. For the spectroscopic studies, changes in the free Pr absorption peaks at 468 and 481 nm were monitored at varying ligand concentrations. The total Pr concentration was 1 x 10 -4 M in solutions used for the photoacoustic studies and 0.02 M for conventional spectroscopy. For the pH titrations, we used solutions whose Pr concentrations varied from 5 x 10 -3 to 5 x 10 -2 M, with total ligand-to-metal ratios ranging from 1 to 10. A comparison of the results obtained by the three techniques demonstrates that photoacoustic spectroscopy can give the same information about metal-ligand speciation as more conventional methods. It is particularly suited to those situations where the other techniques are insensitive because of limited metal concentrations

  19. Absorption technology for solar and waste heat utilization

    International Nuclear Information System (INIS)

    Grossman, G.

    1993-01-01

    Absorption heat pumps, first developed in the 19th century, have received renewed and growing attention in the past two decades. With the increasing cost of oil and electricity, the particular features of this heat-powered cycle have made it attractive for both residential and industrial applications. Solar-powered air conditioning, gas-fired domestic cooling and waste-heat-powered temperature boosters are some of the applications on which intensive research and development has been conducted. This paper describes the operation of absorption systems and discusses several practical applications. It surveys recent advances in absorption technology, including the selection of working fluids, cycle improvements and multi-staging, and fundamentals of the combined heat and mass transfer in absorption processes. (author)

  20. Pathlength Determination for Gas in Scattering Media Absorption Spectroscopy

    Science.gov (United States)

    Mei, Liang; Somesfalean, Gabriel; Svanberg, Sune

    2014-01-01

    Gas in scattering media absorption spectroscopy (GASMAS) has been extensively studied and applied during recent years in, e.g., food packaging, human sinus monitoring, gas diffusion studies, and pharmaceutical tablet characterization. The focus has been on the evaluation of the gas absorption pathlength in porous media, which a priori is unknown due to heavy light scattering. In this paper, three different approaches are summarized. One possibility is to simultaneously monitor another gas with known concentration (e.g., water vapor), the pathlength of which can then be obtained and used for the target gas (e.g., oxygen) to retrieve its concentration. The second approach is to measure the mean optical pathlength or physical pathlength with other methods, including time-of-flight spectroscopy, frequency-modulated light scattering interferometry and the frequency domain photon migration method. By utilizing these methods, an average concentration can be obtained and the porosities of the material are studied. The last method retrieves the gas concentration without knowing its pathlength by analyzing the gas absorption line shape, which depends upon the concentration of buffer gases due to intermolecular collisions. The pathlength enhancement effect due to multiple scattering enables also the use of porous media as multipass gas cells for trace gas monitoring. All these efforts open up a multitude of different applications for the GASMAS technique. PMID:24573311

  1. Pathlength Determination for Gas in Scattering Media Absorption Spectroscopy

    Directory of Open Access Journals (Sweden)

    Liang Mei

    2014-02-01

    Full Text Available Gas in scattering media absorption spectroscopy (GASMAS has been extensively studied and applied during recent years in, e.g., food packaging, human sinus monitoring, gas diffusion studies, and pharmaceutical tablet characterization. The focus has been on the evaluation of the gas absorption pathlength in porous media, which a priori is unknown due to heavy light scattering. In this paper, three different approaches are summarized. One possibility is to simultaneously monitor another gas with known concentration (e.g., water vapor, the pathlength of which can then be obtained and used for the target gas (e.g., oxygen to retrieve its concentration. The second approach is to measure the mean optical pathlength or physical pathlength with other methods, including time-of-flight spectroscopy, frequency-modulated light scattering interferometry and the frequency domain photon migration method. By utilizing these methods, an average concentration can be obtained and the porosities of the material are studied. The last method retrieves the gas concentration without knowing its pathlength by analyzing the gas absorption line shape, which depends upon the concentration of buffer gases due to intermolecular collisions. The pathlength enhancement effect due to multiple scattering enables also the use of porous media as multipass gas cells for trace gas monitoring. All these efforts open up a multitude of different applications for the GASMAS technique.

  2. Light absorption and emission in nanowire array solar cells.

    Science.gov (United States)

    Kupec, Jan; Stoop, Ralph L; Witzigmann, Bernd

    2010-12-20

    Inorganic nanowires are under intense research for large scale solar power generation intended to ultimately contribute a substantial fraction to the overall power mix. Their unique feature is to allow different pathways for the light absorption and carrier transport. In this publication we investigate the properties of a nanowire array acting as a photonic device governed by wave-optical phenomena. We solve the Maxwell equations and calculate the light absorption efficiency for the AM1.5d spectrum and give recommendations on the design. Due to concentration of the incident sunlight at a microscopic level the absorptivity of nanowire solar cells can exceed the absorptivity of an equal amount of material used in thin-film devices. We compute the local density of photon states to assess the effect of emission enhancement, which influences the radiative lifetime of excess carriers. This allows us to compute the efficiency limit within the framework of detailed balance. The efficiency is highly sensitive with respect to the diameter and distance of the nanowires. Designs featuring nanowires below a certain diameter will intrinsically feature low short-circuit current that cannot be compensated even by increasing the nanowire density. Optimum efficiency is not achieved in densely packed arrays, in fact spacing the nanowires further apart (simultaneously decreasing the material use) can even improve efficiency in certain scenarios. We observe absorption enhancement reducing the material use. In terms of carrier generation per material use, nanowire devices can outperform thin-film devices by far.

  3. Performance of direct absorption solar collector with nanofluid mixture

    International Nuclear Information System (INIS)

    Turkyilmazoglu, Mustafa

    2016-01-01

    Highlights: • Neat approximations for temperature and solar collector efficiency are presented. • The non-adiabatic and isothermal base mechanisms optimize the surface absorption. • Heat transferring material at the bottom panel enhances the thermal efficiency. • Isothermal base panel leads to maximum thermal efficiency of the solar receiver. - Abstract: The enhancement of performance by increasing the thermal efficiency of a direct absorption solar collector based on an alumina–water nanofluid is the prime target of the present research. The base panel of the collector channel is subject to either a non adiabatic or an isothermal wall condition both of which introduce two new physical parameters. Analytical solutions for the temperature field are worked out in both cases for a two dimensional steady-state model recently outlined in the literature. The desired increase in the temperature of the heat transferring nanofluid is achieved either by slightly rising the heat transfer coefficient of the bottom panel coating or by prescribing a bottom surface temperature. As a consequence of the increase in the final outlet mean temperature, the solar collector thermal efficiency is found to be enhanced via increasing the new physical parameters as compared to the traditional adiabatic wall case. For instance, 85.63% thermal efficiency of solar collector is achievable for non adiabatic bottom panel by adding suspended aluminum nanoparticles into the pure water. Even better than this, considering isothermal base panels, 100% efficiency is attained more rapidly with lesser base temperatures in the presence of higher nanoparticle volume fractions.

  4. Design of solar cell materials via soft X-ray spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Himpsel, F.J., E-mail: fhimpsel@wisc.edu [Department of Physics, University of Wisconsin Madison, Madison, WI 53706 (United States); Cook, P.L. [Natural Sciences Department, University of Wisconsin Superior, Superior, WI 54880 (United States); Torre, G. de la [Departamento de Química Orgánica, Facultad de Ciencias, Universidad Autónoma de Madrid, Campus de Cantoblanco, 28049 Madrid (Spain); Garcia-Lastra, J.M. [Material Physics Center (MPC), Centro de Física de Materiales (CSIC-UPV/EHU), Donostia International Physics Center - DIPC, Departamento de Fisica Aplicada I, Universidad del Pais Vasco, 20018 San Sebastian (Spain); Department of Physics, Center for Atomic-scale Materials Design, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark); Gonzalez-Moreno, R. [Material Physics Center (MPC), Centro de Física de Materiales (CSIC-UPV/EHU), Donostia International Physics Center - DIPC, Departamento de Fisica Aplicada I, Universidad del Pais Vasco, 20018 San Sebastian (Spain); Guo, J.-H. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Hamers, R.J. [Department of Chemistry, University of Wisconsin Madison, Madison, WI 53706 (United States); Kronawitter, C.X. [Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Johnson, P.S. [Department of Physics, University of Wisconsin Madison, Madison, WI 53706 (United States); Ortega, J.E.; Pickup, D. [Material Physics Center (MPC), Centro de Física de Materiales (CSIC-UPV/EHU), Donostia International Physics Center - DIPC, Departamento de Fisica Aplicada I, Universidad del Pais Vasco, 20018 San Sebastian (Spain); and others

    2013-10-15

    Highlights: ► The use of soft X-ray spectroscopy for developing new materials for solar cells is illustrated. ► A generic layout of a solar cell is given, which facilitates the discussion of the energy levels involved in a solar cell and their optimization. ► Systematic measurements of organometallic dyes are presented in combination with density functional theory. ► The data reveal trends that are useful for tailoring materials for solar cells. ► A solar cell design based on thin film p-type diamond as donor is used as example. -- Abstract: This overview illustrates how spectroscopy with soft X-rays can assist the development of new materials and new designs for solar cells. The starting point is the general layout of a solar cell, which consists of a light absorber sandwiched between an electron donor and an electron acceptor. There are four relevant energy levels that can be measured with a combination of X-ray absorption spectroscopy and photoelectron spectroscopy, as illustrated for an organic dye as absorber attached to a p-doped diamond film as donor. Systematic measurements of organometallic dyes (phthalocyanines and porphyrins) as a function of the metal atom are presented for the metal 2p and N 1s absorption edges. In combination with density functional theory one can discern trends that are useful for tailoring absorber molecules. A customized porphyrin molecule is investigated that combines an absorber with a donor and a linker to an oxide acceptor. The bridge to device fabrication is crossed by correlating spectroscopic features with the photocurrent in hematite photoanodes for water splitting. For speeding up the development of new materials and designs of solar cells a feedback loop between spectroscopy, theory, synthesis and device fabrication is envisioned.

  5. Diagnostic potential of cosmic-neutrino absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Barenboim, Gabriela; /Valencia U.; Mena Requejo, Olga; Quigg, Chris; /Fermilab

    2004-12-01

    Annihilation of extremely energetic cosmic neutrinos on the relic-neutrino background can give rise to absorption lines at energies corresponding to formation of the electroweak gauge boson Z{sup 0}. The positions of the absorption dips are set by the masses of the relic neutrinos. Suitably intense sources of extremely energetic (10{sup 21} - 10{sup 25}-eV) cosmic neutrinos might therefore enable the determination of the absolute neutrino masses and the flavor composition of the mass eigenstates. Several factors--other than neutrino mass and composition--distort the absorption lines, however. We analyze the influence of the time-evolution of the relic-neutrino density and the consequences of neutrino decay. We consider the sensitivity of the lineshape to the age and character of extremely energetic neutrino sources, and to the thermal history of the Universe, reflected in the expansion rate. We take into account Fermi motion arising from the thermal distribution of the relic-neutrino gas. We also note the implications of Dirac vs. Majorana relics, and briefly consider unconventional neutrino histories. We ask what kinds of external information would enhance the potential of cosmic-neutrino absorption spectroscopy, and estimate the sensitivity required to make the technique a reality.

  6. The determination of vanadium in brines by atomic absorption spectroscopy

    Science.gov (United States)

    Crump-Wiesner, Hans J.; Feltz, H.R.; Purdy, W.C.

    1971-01-01

    A standard addition method is described for the determination of vanadium in brines by atomic absorption spectroscopy with a nitrous oxide-acetylene flame. Sample pH is adjusted to 1.0 with concentrated hydrochloric acid and the vanadium is directly extracted with 5% cupferron in methyl isobutyl ketone (MIBK). The ketone layer is then aspirated into the flame and the recorded absorption values are plotted as a function of the concentration of the added metal. As little as 2.5 ??g l-1 of vanadium can be detected under the conditions of the procedure. Tungsten and tin interfere when present in excess of 5 and 10 ??g ml-1, respectively. The concentrations of the two interfering ions normally found in brines are well below interference levels. ?? 1971.

  7. Evaluation of DNA damage using microwave dielectric absorption spectroscopy

    International Nuclear Information System (INIS)

    Hirayama, Makoto; Matuo, Youichrou; Izumi, Yoshinobu; Sunagawa, Takeyoshi

    2016-01-01

    Evaluation of deoxyribonucleic acid (DNA)-strand break is important to elucidate the biological effect of ionizing radiations. The conventional methods for DNA-strand break evaluation have been achieved by Agarose gel electrophoresis and others using an electrical property of DNAs. Such kinds of DNA-strand break evaluation systems can estimate DNA-strand break, according to a molecular weight of DNAs. However, the conventional method needs pre-treatment of the sample and a relatively long period for analysis. They do not have enough sensitivity to detect the strand break products in the low-dose region. The sample is water, methanol and plasmid DNA solution. The plasmid DNA pUC118 was multiplied by using Escherichia coli JM109 competent cells. The resonance frequency and Q-value were measured by means of microwave dielectric absorption spectroscopy. When a sample is located at a center of the electric field, resonance curve of the frequency that existed as a standing wave is disturbed. As a result, the perturbation effect to perform a resonance with different frequency is adopted. The resonance frequency shifted to higher frequency with an increase in a concentration of methanol as the model of the biological material, and the Q-value decreased. The absorption peak in microwave power spectrum of the double-strand break plasmid DNA shifted from the non-damaged plasmid DNA. Moreover, the sharpness of absorption peak changed resulting in change in Q-value. We confirmed that a resonance frequency shifted to higher frequency with an increase in concentration of the plasmid DNA. We developed a new technique for an evaluation of DNA damage. In this paper, we report the evaluation method of DNA damage using microwave dielectric absorption spectroscopy

  8. Evaluation of DNA damage using microwave dielectric absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hirayama, Makoto; Matuo, Youichrou; Izumi, Yoshinobu [Research Institute of Nuclear Engineering, University of Fukui, Fukui (Japan); Sunagawa, Takeyoshi [Fukui University of Technology, Fukui (Japan)

    2016-12-15

    Evaluation of deoxyribonucleic acid (DNA)-strand break is important to elucidate the biological effect of ionizing radiations. The conventional methods for DNA-strand break evaluation have been achieved by Agarose gel electrophoresis and others using an electrical property of DNAs. Such kinds of DNA-strand break evaluation systems can estimate DNA-strand break, according to a molecular weight of DNAs. However, the conventional method needs pre-treatment of the sample and a relatively long period for analysis. They do not have enough sensitivity to detect the strand break products in the low-dose region. The sample is water, methanol and plasmid DNA solution. The plasmid DNA pUC118 was multiplied by using Escherichia coli JM109 competent cells. The resonance frequency and Q-value were measured by means of microwave dielectric absorption spectroscopy. When a sample is located at a center of the electric field, resonance curve of the frequency that existed as a standing wave is disturbed. As a result, the perturbation effect to perform a resonance with different frequency is adopted. The resonance frequency shifted to higher frequency with an increase in a concentration of methanol as the model of the biological material, and the Q-value decreased. The absorption peak in microwave power spectrum of the double-strand break plasmid DNA shifted from the non-damaged plasmid DNA. Moreover, the sharpness of absorption peak changed resulting in change in Q-value. We confirmed that a resonance frequency shifted to higher frequency with an increase in concentration of the plasmid DNA. We developed a new technique for an evaluation of DNA damage. In this paper, we report the evaluation method of DNA damage using microwave dielectric absorption spectroscopy.

  9. Detection of atomic oxygen in flames by absorption spectroscopy

    International Nuclear Information System (INIS)

    Cheskis, S.; Kovalenko, S.A.

    1994-01-01

    The absolute concentration of atomic oxygen in an atmospheric pressure hydrogen/air flame has been measured using Intracavity Laser Spectroscopy (ICLS) based on a dye laser pumped by an argon-ion laser. Absorptions at the highly forbidden transitions at 630.030 nm and 636.380 nm were observed at an equivalent optical length of up to 10 km. The relatively low intensity of the dye laser avoids photochemical interferences that are inherent to some other methods for detecting atomic oxygen. The detection sensitivity is about 6x10 14 atom/cm 3 and can be improved with better flame and laser stabilization. (orig.)

  10. Study on Differential Optical Absorption Spectroscopy : Technique and its Applications

    OpenAIRE

    Liu, Jianguo

    2002-01-01

    ln the first part of speech, with a description of the principle of DOAS (Differential Optical Absorption Spectroscopy), the design and realization of two different kinds of DOAS systems are nresented. 0ne is using a slotted disc raoid scanning device with a photomultiplier, which is suitable for ambient air quality measurement. It can measure total 16 kinds of pollutants such as SO_2, NO, N02, NH_3, O_3, C_6H_6, C_7H_8 and CH_2O etc., with detection limits of 1-2ppb. The other is using a UV ...

  11. Cavity Enhanced Absorption Spectroscopy in Air Pollution Monitoring

    Directory of Open Access Journals (Sweden)

    Janusz MIKOŁAJCZYK

    2015-10-01

    Full Text Available The paper presents some practical aspects of cavity enhanced absorption spectroscopy application in detection of nitrogen dioxide (NO2, nitrous oxide (N2O, nitric oxide (NO and carbon monoxide (CO. These gases are very important for monitoring of environment. There are shown results of lab-setups for N2O, NO, CO detection and portable sensor of NO2. The portable instrument operates in the UV spectral range and reaches a level of single ppb. The lab–devices use high precision mid-infrared spectroscopy and they was demonstrated during testing the laboratory air. These sensors are able to measure concentration at the ppb level using quantum cascade lasers, high quality optical cavities and modern MCT detection modules. It makes it possible to apply such sensors in monitoring the atmosphere quality.

  12. Testing and further development of a solar absorption cooling plant

    Science.gov (United States)

    Amannsberger, K.; Heckel, H.; Kreutmair, J.; Weber, K. H.

    1984-12-01

    Ammonia water absorption cooling units using the process heat of line-focusing solar collectors were developed and tested. Reduction of the evaporation temperature to minus 10 C; development of an air-cooled rectifying device for the refrigerant vapor; dry cooling of absorber and condenser by natural draft; refrigerating capacities of 14 to 10 kW which correspond to air temperatures of 25 to 40 C and 24 kW power consumption to heat the machine; auxiliary power requirement 450 W; full compatibility with changing heat input and air temperature, adaptation by automatic stabilization effects; and power optimization under changing boundary conditions by a simple regulating procedure independent of auxiliary power are achieved. The dynamic behavior of the directly linked collector-refrigeration machine system was determined. Operating conditions, market, and economic viability of solar cooling in third-world countries are described. Ice production procedures using absorption cooling units are demonstrated.

  13. Field Measurements of Water Continuum and Water Dimer Absorption by Active Long Path Differential Optical Absorption Spectroscopy (DOAS)

    OpenAIRE

    Lotter, Andreas

    2006-01-01

    Water vapor plays an important role in Earth's radiative budget since water molecules strongly absorb the incoming solar shortwave and the outgoing thermal infrared radiation. Superimposed on the water monomer absorption, a water continuum absorption has long been recognized, but its true nature still remains controversial. On the one hand, this absorption is explained by a deformation of the line shape of the water monomer absorption lines as a consequence of a molecular collision. One the o...

  14. Dynamic model of an autonomous solar absorption refrigerator

    International Nuclear Information System (INIS)

    Ali Fellah; Tahar Khir; Ammar Ben Brahim

    2009-01-01

    The performance analysis of a solar absorption refrigerator operating in an autonomous way is investigated. The water/LiBr machine satisfies the air-conditioning needs along the day. The refrigerator performances were simulated regarding a dynamic model. For the solar driven absorption machines, two applications could be distinguished. The sun provides the thermal part of the useful energy. In this case, it is necessary to use additional energy as the electric one to activate the pumps, the fans and the control system. On the other hand, the sun provides all the necessary energy. Here, both photovoltaic cells and thermal concentrators should be used. The simulation in dynamic regime of the cycle requires the knowledge of the geometric characteristics of every component as the exchange areas and the internal volumes. Real characteristics of a refrigerator available at the applied thermodynamic research unit (ATRU) at the engineers' national school of Gabes are notified. The development of the thermal and matter balances in every component of the cycle has permitted to simulate in dynamic regime the performances of a solar absorption refrigerator operating with the water/LiBr couple for air-conditioning needs. The developed model could be used to perform intermittent refrigeration cycle autonomously driven. (author)

  15. Solar active envelope module with an adjustable transmittance/absorptance

    Directory of Open Access Journals (Sweden)

    C. Villasante Villasante

    2015-06-01

    Full Text Available A solar active envelope module with a high flexibility degree is proposed in this paper. The transparent module controls the day-lighting of the room, improving the indoor environment, while absorbing the superfluous solar energy inside. That energy is used to increase the efficiency of heating, ventilation, and the air-conditioning (HVAC system of the building. This is carried out through a fine control of the absorptance of the envelope module. The active envelope module consists of three glazed chambers with advanced coatings and frames to assure a minimum thermal transmittance while allowing transparency. A fluid containing heat-absorbing nanoparticles flows inside the central chamber and is heated up due to the impinging solar energy. Unlike other systems proposed in the past, which included transparency control systems based on complex filters and chemical processes, the absorption of the module is controlled by the variation of the thickness of the central chamber with a mechanical device. That is, varying the thickness of the central chamber, it allows controlling the absorptance of the whole system and, as a result, indoor day-lighting and thermal loads. Therefore, a new system is proposed that enables to:  

  16. Probing the CZTS/CdS heterojunction utilizing photoelectrochemistry and x-ray absorption spectroscopy

    Science.gov (United States)

    Turnbull, Matthew J.; Vaccarello, Daniel; Wong, Jonathan; Yiu, Yun Mui; Sham, Tsun-Kong; Ding, Zhifeng

    2018-04-01

    The importance of renewable resources is becoming more and more influential on research due to the depletion of fossil fuels. Cost-effective ways of harvesting solar energy should also be at the forefront of these investigations. Cu2ZnSnS4 (CZTS) solar cells are well within the frame of these goals, and a thorough understanding of how they are made and processed synthetically is crucial. The CZTS/CdS heterojunction was examined using photoelectrochemistry and synchrotron radiation (SR) spectroscopy. These tools provided physical insights into this interface that was formed by the electrophoretic deposition of CZTS nanocrystals and chemical bath deposition (CBD) of CdS for the respective films. It was discovered that CBD induced a change in the local and long range environment of the Zn in the CZTS lattice, which was detrimental to the photoresponse. X-ray absorption near-edge structures and extended X-ray absorption fine structures (EXAFSs) of the junction showed that this change was at an atomic level and was associated with the coordination of oxygen to zinc. This was confirmed through FEFF fitting of the EXAFS and through IR spectroscopy. It was found that this change in both photoresponse and the Zn coordination can be reversed with the use of low temperature annealing. Investigating CZTS through SR techniques provides detailed structural information of minor changes from the zinc perspective.

  17. Nanofluid optical property characterization: towards efficient direct absorption solar collectors

    Directory of Open Access Journals (Sweden)

    Otanicar Todd

    2011-01-01

    Full Text Available Abstract Suspensions of nanoparticles (i.e., particles with diameters < 100 nm in liquids, termed nanofluids, show remarkable thermal and optical property changes from the base liquid at low particle loadings. Recent studies also indicate that selected nanofluids may improve the efficiency of direct absorption solar thermal collectors. To determine the effectiveness of nanofluids in solar applications, their ability to convert light energy to thermal energy must be known. That is, their absorption of the solar spectrum must be established. Accordingly, this study compares model predictions to spectroscopic measurements of extinction coefficients over wavelengths that are important for solar energy (0.25 to 2.5 μm. A simple addition of the base fluid and nanoparticle extinction coefficients is applied as an approximation of the effective nanofluid extinction coefficient. Comparisons with measured extinction coefficients reveal that the approximation works well with water-based nanofluids containing graphite nanoparticles but less well with metallic nanoparticles and/or oil-based fluids. For the materials used in this study, over 95% of incoming sunlight can be absorbed (in a nanofluid thickness ≥10 cm with extremely low nanoparticle volume fractions - less than 1 × 10-5, or 10 parts per million. Thus, nanofluids could be used to absorb sunlight with a negligible amount of viscosity and/or density (read: pumping power increase.

  18. Experimental Investigation on an Absorption Refrigerator Driven by Solar Cells

    Directory of Open Access Journals (Sweden)

    Zi-Jie Chien

    2013-01-01

    Full Text Available This experiment is to study an absorption refrigerator driven by solar cells. Hand-held or carried in vehicle can be powered by solar energy in places without power. In the evenings or rainy days, it is powered by storage battery, and it can be directly powered by alternating current (AC power supply if available, and the storage battery can be charged full as a backup supply. The proposed system was tested by the alternation of solar irradiance 550 to 700 W/m2 as solar energy and 500ml ambient temperature water as cooling load. After 160 minutes, the proposal refrigerator can maintain the temperature at 5–8°C, and the coefficient of performance (COP of NH3-H2O absorption refrigeration system is about 0.25. Therefore, this system can be expected to be used in remote areas for refrigeration of food and beverages in outdoor activities in remote and desert areas or long-distance road transportation of food or low temperature refrigeration of vaccine to avoid the deterioration of the food or the vaccines.

  19. Improvements in absorption systems for solar air conditioning

    Energy Technology Data Exchange (ETDEWEB)

    Grossman, G. (Oak Ridge National Lab., TN); Bourne, J.R.; Ben-Dror, J.; Kimchi, Y.; Vardi, I.

    1981-01-01

    A theoretical evaluation is described of two design improvements made in a lithium bromide absorption chiller which increase its efficiency and operating range in solar applications. One is the addition of a solution preheater which allows for a considerable reduction in generator size and cost, and improves performance at part load. The other is the addition of an auxiliary generator which enables the chiller to operate at nominal capacity or higher at all times, while utilizing to a maximum the solar radiation available at the time, however small. This is an effective solution to the problem of back-up required in all solar powered systems. The evaluation has been performed by computer simulation and results are presented for the performance of the unit with different configurations of the above systems.

  20. Non-linear absorption for concentrated solar energy transport

    Energy Technology Data Exchange (ETDEWEB)

    Jaramillo, O. A; Del Rio, J.A; Huelsz, G [Centro de Investigacion de Energia, UNAM, Temixco, Morelos (Mexico)

    2000-07-01

    In order to determine the maximum solar energy that can be transported using SiO{sub 2} optical fibers, analysis of non-linear absorption is required. In this work, we model the interaction between solar radiation and the SiO{sub 2} optical fiber core to determine the dependence of the absorption of the radioactive intensity. Using Maxwell's equations we obtain the relation between the refractive index and the electric susceptibility up to second order in terms of the electric field intensity. This is not enough to obtain an explicit expression for the non-linear absorption. Thus, to obtain the non-linear optical response, we develop a microscopic model of an harmonic driven oscillators with damp ing, based on the Drude-Lorentz theory. We solve this model using experimental information for the SiO{sub 2} optical fiber, and we determine the frequency-dependence of the non-linear absorption and the non-linear extinction of SiO{sub 2} optical fibers. Our results estimate that the average value over the solar spectrum for the non-linear extinction coefficient for SiO{sub 2} is k{sub 2}=10{sup -}29m{sup 2}V{sup -}2. With this result we conclude that the non-linear part of the absorption coefficient of SiO{sub 2} optical fibers during the transport of concentrated solar energy achieved by a circular concentrator is negligible, and therefore the use of optical fibers for solar applications is an actual option. [Spanish] Con el objeto de determinar la maxima energia solar que puede transportarse usando fibras opticas de SiO{sub 2} se requiere el analisis de absorcion no linear. En este trabajo modelamos la interaccion entre la radiacion solar y el nucleo de la fibra optica de SiO{sub 2} para determinar la dependencia de la absorcion de la intensidad radioactiva. Mediante el uso de las ecuaciones de Maxwell obtenemos la relacion entre el indice de refraccion y la susceptibilidad electrica hasta el segundo orden en terminos de intensidad del campo electrico. Esto no es

  1. Femtosecond transient absorption spectroscopy of silanized silicon quantum dots

    Science.gov (United States)

    Kuntermann, Volker; Cimpean, Carla; Brehm, Georg; Sauer, Guido; Kryschi, Carola; Wiggers, Hartmut

    2008-03-01

    Excitonic properties of colloidal silicon quantum dots (Si qdots) with mean sizes of 4nm were examined using stationary and time-resolved optical spectroscopy. Chemically stable silicon oxide shells were prepared by controlled surface oxidation and silanization of HF-etched Si qdots. The ultrafast relaxation dynamics of photogenerated excitons in Si qdot colloids were studied on the picosecond time scale from 0.3psto2.3ns using femtosecond-resolved transient absorption spectroscopy. The time evolution of the transient absorption spectra of the Si qdots excited with a 150fs pump pulse at 390nm was observed to consist of decays of various absorption transitions of photoexcited electrons in the conduction band which overlap with both the photoluminescence and the photobleaching of the valence band population density. Gaussian deconvolution of the spectroscopic data allowed for disentangling various carrier relaxation processes involving electron-phonon and phonon-phonon scatterings or arising from surface-state trapping. The initial energy and momentum relaxation of hot carriers was observed to take place via scattering by optical phonons within 0.6ps . Exciton capturing by surface states forming shallow traps in the amorphous SiOx shell was found to occur with a time constant of 4ps , whereas deeper traps presumably localized in the Si-SiOx interface gave rise to exciton trapping processes with time constants of 110 and 180ps . Electron transfer from initially populated, higher-lying surface states to the conduction band of Si qdots (>2nm) was observed to take place within 400 or 700fs .

  2. X-ray absorption spectroscopy of photoionised plasmas at Z

    Science.gov (United States)

    Mancini, R. C.

    2011-06-01

    Photoionised plasmas are found in astrophysical environments such as x-ray binaries, active galactic nuclei, and in the accretion disks of compact objects. The Z facility at Sandia National Laboratories is a powerful source of x-rays that enables us to produce and study in the laboratory photoionised plasmas relevant for astrophysics under well characterized conditions. We discuss an experimental and theory/modeling effort in which the intense x-ray flux emitted at the collapse of a z-pinch experiment conducted at Z is employed to produce a neon photoionized plasma. The broad-band x-ray radiation flux from the z-pinch is used to both create the neon photoionised plasma and provide a source of backlighting photons to study the atomic kinetics through K-shell line absorption spectroscopy. The plasma is contained in a cm-scale gas cell located at about 5 cm from the z-pinch, and the filling pressure is carefully monitored all the way to shot time since it determines the particle number density of the plasma. Time-integrated and gated transmission spectra are recorded with a TREX spectrometer equipped with two elliptically-bent crystals and a set of slits to record up to six spatially-resolved spectra per crystal in the same shot. The spectral resolution is approximately 1000. The transmission data shows line absorption transitions in several ionization stages of neon including Be-, Li-, He- and H-like Ne ions. Detailed modeling calculations of the absorption spectra are used to interpret and model the high-resolution transmission spectra recorded in the Z experiments with the goal of extracting the ion population distribution of the plasma. Furthermore, the analysis of the gated data provides a window into the dynamics of the photoionized plasma. The data analysis is performed with the aid of a novel application of genetic algorithms to plasma spectroscopy.

  3. Investigation of pollutant gases with molecular absorption spectroscopy

    International Nuclear Information System (INIS)

    Izairi, N; Ajredini, F.; Shehabi, M.

    2011-01-01

    This paper contains the molecular absorption spectroscopic investigation on environmental pollution by many pollutants. For this purpose a laser absorption spectroscopy at 630 nm wavelength has been applied to excite the molecular spectra in order to identify the presence of main gas pollutants. The following was the experimental procedure. Preliminary the presence of pollutants was identified. The gas champions were taken in live environment, in Tetovo streets where cars moved, and in some points in Tetovo suburbia, during different periods of the day. A special civet, part of the apparatus, has been filled by environmental air, and latter, put into the apparatus. A laser beam pulse passes throughout absorbing gas medium in the civet to excite the gas, and the absorbing spectra were automatically registered. The molecular band spectra registration has been performed by an FT-IR Spectrometer (Spectrum BX FT-IR Perkin Elmer). For this purpose the measurements were focused in spectral region of 2075 cm -1 to 2384 cm -1 for CO 2 and CO bands investigation. The importance of such measurements is to investigate the spectral properties of absorption spectra and molecular structure, and for monitoring the environmental pollution. (Author)

  4. Precision atomic beam density characterization by diode laser absorption spectroscopy

    International Nuclear Information System (INIS)

    Oxley, Paul; Wihbey, Joseph

    2016-01-01

    We provide experimental and theoretical details of a simple technique to determine absolute line-of-sight integrated atomic beam densities based on resonant laser absorption. In our experiments, a thermal lithium beam is chopped on and off while the frequency of a laser crossing the beam at right angles is scanned slowly across the resonance transition. A lock-in amplifier detects the laser absorption signal at the chop frequency from which the atomic density is determined. The accuracy of our experimental method is confirmed using the related technique of wavelength modulation spectroscopy. For beams which absorb of order 1% of the incident laser light, our measurements allow the beam density to be determined to an accuracy better than 5% and with a precision of 3% on a time scale of order 1 s. Fractional absorptions of order 10 −5 are detectable on a one-minute time scale when we employ a double laser beam technique which limits laser intensity noise. For a lithium beam with a thickness of 9 mm, we have measured atomic densities as low as 5 × 10 4 atoms cm −3 . The simplicity of our technique and the details we provide should allow our method to be easily implemented in most atomic or molecular beam apparatuses.

  5. Precision atomic beam density characterization by diode laser absorption spectroscopy.

    Science.gov (United States)

    Oxley, Paul; Wihbey, Joseph

    2016-09-01

    We provide experimental and theoretical details of a simple technique to determine absolute line-of-sight integrated atomic beam densities based on resonant laser absorption. In our experiments, a thermal lithium beam is chopped on and off while the frequency of a laser crossing the beam at right angles is scanned slowly across the resonance transition. A lock-in amplifier detects the laser absorption signal at the chop frequency from which the atomic density is determined. The accuracy of our experimental method is confirmed using the related technique of wavelength modulation spectroscopy. For beams which absorb of order 1% of the incident laser light, our measurements allow the beam density to be determined to an accuracy better than 5% and with a precision of 3% on a time scale of order 1 s. Fractional absorptions of order 10 -5 are detectable on a one-minute time scale when we employ a double laser beam technique which limits laser intensity noise. For a lithium beam with a thickness of 9 mm, we have measured atomic densities as low as 5 × 10 4 atoms cm -3 . The simplicity of our technique and the details we provide should allow our method to be easily implemented in most atomic or molecular beam apparatuses.

  6. Optical re-injection in cavity-enhanced absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Leen, J. Brian, E-mail: b.leen@lgrinc.com; O’Keefe, Anthony [Los Gatos Research, 67 E. Evelyn Avenue, Suite 3, Mountain View, California 94041 (United States)

    2014-09-15

    Non-mode-matched cavity-enhanced absorption spectrometry (e.g., cavity ringdown spectroscopy and integrated cavity output spectroscopy) is commonly used for the ultrasensitive detection of trace gases. These techniques are attractive for their simplicity and robustness, but their performance may be limited by the reflection of light from the front mirror and the resulting low optical transmission. Although this low transmitted power can sometimes be overcome with higher power lasers and lower noise detectors (e.g., in the near-infrared), many regimes exist where the available light intensity or photodetector sensitivity limits instrument performance (e.g., in the mid-infrared). In this article, we describe a method of repeatedly re-injecting light reflected off the front mirror of the optical cavity to boost the cavity's circulating power and deliver more light to the photodetector and thus increase the signal-to-noise ratio of the absorption measurement. We model and experimentally demonstrate the method's performance using off-axis cavity ringdown spectroscopy (OA-CRDS) with a broadly tunable external cavity quantum cascade laser. The power coupled through the cavity to the detector is increased by a factor of 22.5. The cavity loss is measured with a precision of 2 × 10{sup −10} cm{sup −1}/√(Hz;) an increase of 12 times over the standard off-axis configuration without reinjection and comparable to the best reported sensitivities in the mid-infrared. Finally, the re-injected CRDS system is used to measure the spectrum of several volatile organic compounds, demonstrating the improved ability to resolve weakly absorbing spectroscopic features.

  7. Acceptor and Excitation Density Dependence of the Ultrafast Polaron Absorption Signal in Donor-Acceptor Organic Solar Cell Blends.

    Science.gov (United States)

    Zarrabi, Nasim; Burn, Paul L; Meredith, Paul; Shaw, Paul E

    2016-07-21

    Transient absorption spectroscopy on organic semiconductor blends for solar cells typically shows efficient charge generation within ∼100 fs, accounting for the majority of the charge carriers. In this Letter, we show using transient absorption spectroscopy on blends containing a broad range of acceptor content (0.01-50% by weight) that the rise of the polaron signal is dependent on the acceptor concentration. For low acceptor content (10%) most polarons are generated within 200 fs. The rise time in blends with low acceptor content was also found to be sensitive to the pump fluence, decreasing with increasing excitation density. These results indicate that the sub-100 fs rise of the polaron signal is a natural consequence of both the high acceptor concentrations in many donor-acceptor blends and the high excitation densities needed for transient absorption spectroscopy, which results in a short average distance between the exciton and the donor-acceptor interface.

  8. Surface Texturing Investigated for a High Solar Absorptance Low Infrared Emittance Solar Collector

    Science.gov (United States)

    Jaworske, Donald A.

    2001-01-01

    The objective of this work was to design, build, and vacuum test a high solar absorptance, low infrared emittance solar collector for heat engine and thermal switching applications. Mini-satellites proposed by the Applied Physics Laboratory for operation in environments that are subject to radiation threat may utilize a heat engine for power and a thermal bus for thermal control. To achieve this goal, a surface having high solar absorptance and low infrared emittance is needed. At the NASA Glenn Research Center, one concept being pursued to achieve this goal is texturing high thermal conductivity graphite epoxy composites using a directed atomic oxygen beam and then coating the textured surface with a reflective metallic coating. Coupons were successfully textured, coated, and evaluated. A variety of texturing conditions were explored, and textures were documented by scanning electron microscopy. Copper, gold, silver, iridium, and aluminum coatings were applied, and the highest solar absorptance to infrared emittance ratio was found to be 1.3. A full-sized solar collector was manufactured with this ratio, and the amount of heat collected was observed using an Inconel calorimeter installed in a bench-top vacuum chamber equipped with a solar simulator. Results to date indicate good heat flow through the system, with 9 W of heat flow measured by the calorimeter.

  9. Performance of a compact solar absorption cooling system

    International Nuclear Information System (INIS)

    Mulyanef; Kamaruzzaman Sopian

    2006-01-01

    This paper describes the performance of a compact solar absorption system. Purpose of compact solar is collector, generator and condenser in one unit. At present, two types of absorption cooling systems are marketed: the lithium bromide-water system and the ammonia-water system. In the lithium bromide-water system, water vapor is the refrigerant and ammonia water system where ammonia is the refrigerant. In addition, the ammonia-water system requires higher generator temperature 120 o C to 150 o C than a flat-plate solar collector can provide without special techniques. The lithium bromide-water system operates satisfactorily at a generator temperature of 75 o C to 100 o C, achievable by a flat-plate collector. The lithium bromide-water system also has a higher COP than the ammonia-water system. The disadvantage of the lithium bromide-water systems is that the evaporators cannot operate at temperature below 0 o C since the refrigerant is water. The Coefficient of Performance (COP) system is 0.62 and the concentration of LiBr-H 2 O is 50%

  10. Determination of lead in mother's milk by atomic absorption spectroscopy

    International Nuclear Information System (INIS)

    Bandarchian, F.; Assadian, F

    2002-01-01

    With due attention to increasing air pollution specially the lead amount that is generated from gasoline burning in automobiles, it seems that it is necessary to control the amount of it continuously. Because Pb has an easy absorbability to body and also damages the nervous system. For this reason determination of it in mother's milk has a special importance. In this research, the milks of 15 mothers twice a day were examined and the concentration of Pb were determined by atomic absorption spectroscopy. In accordance the international organization, the permissible amount in body is 0.05 ppm. Fortunately, the obtained data was less than of it and it showed the absorbance of lead by babies is insignificant

  11. Mercury pollution surveys in Riga by Zeeman atomic absorption spectroscopy

    International Nuclear Information System (INIS)

    Gavare, Z.; Bogans, E.; Svagere, A.

    2008-01-01

    Practical sessions of mercury pollution measurements in Riga (Latvia) have been performed in several districts using an RA-915+ Zeeman atomic absorption spectrometer coupled with a global positioning system (GPS). The measurements were taken from a driving car and in different days at one particular location (the Institute of Atomic Physics and Spectroscopy) for monitoring the changes in atmospheric mercury concentration. GPS was used to relate the measurement results to particular places, which made it possible to create a digitalized database of pollution for different geographic coordinates in different time spans. The measurements have shown that the background level of mercury concentration in Riga does not exceed 5 ng/m 3 , although there are several areas of elevated mercury pollution that need particular attention. (Authors)

  12. Vanadium Oxidation State Determination by X-Ray Absorption Spectroscopy

    Science.gov (United States)

    Duchesne, Marc A.; Nakano, Jinichiro; Hu, Yongfeng; MacLennan, Aimee; Hughes, Robin W.; Bennett, James; Nakano, Anna

    Vanadium is found in slags produced during metal refinement and fossil fuel combustion/gasification. The oxidation state of vanadium in slag has technological and environmental implications. For example, it may affect slag flow and refractory wear inside reactors, as well as leachability and toxicity of industrial by-products. Determination of vanadium's oxidation state in crystalline phases can be achieved via the widely adopted X-ray diffraction (XRD) technique. However, this technique does not provide information on vanadium in amorphous phases. The objective of this research is to determine the oxidation state of vanadium in petroleum coke gasification samples and laboratory samples using X-ray absorption spectroscopy (XAS) with Canadian Light Source's soft X-ray micro-characterization beamline (SXRMB). Linear combination fitting of XAS spectra with reference samples allowed quantitative determination of vanadium speciation.

  13. Arsenic speciation in solids using X-ray absorption spectroscopy

    Science.gov (United States)

    Foster, Andrea L.; Kim, Chris S.

    2014-01-01

    Synchrotron-based X-ray absorption spectroscopy (XAS) is an in situ, minimally-destructive, element-specific, molecular-scale structural probe that has been employed to study the chemical forms (species) of arsenic (As) in solid and aqueous phases (including rocks, soils, sediment, synthetic compounds, and numerous types of biota including humans) for more than 20 years. Although several excellent reviews of As geochemistry and As speciation in the environment have been published previously (including recent contributions in this volume), the explosion of As-XAS studies over the past decade (especially studies employing microfocused X-ray beams) warrants this new review of the literature and of data analysis methods.

  14. Broken-cloud enhancement of solar radiation absorption

    Energy Technology Data Exchange (ETDEWEB)

    Byrne, R.N. [Science Applications International Corporation, San Diego, CA (United States); Somerville, R.C. [Univ. of California, La Jolla, CA (United States); Subasilar, B. [Curtain Univ. of Technology, Perth (Australia)

    1996-04-01

    Two papers recently published in Science have shown that there is more absorption of solar radiation than estimated by current atmospheric general circulation models (GCMs) and that the discrepancy is associated with cloudy scenes. We have devised a simple model which explains this as an artifact of stochastic radiative transport. We first give a heuristic description, unencumbered by mathematical detail. Consider a simple case with clouds distributed at random within a single level whose upper and lower boundaries are fixed. The solar zenith angle is small to moderate; this is therefore an energetically important case. Fix the average areal liquid water content of the cloud layer, and take the statistics of the cloud distribution to be homogeneous within the layer. Furthermore, assume that all the clouds in the layer have the same liquid water content, constant throughout the cloud, and that apart from their droplet content they are identical to the surrounding clear sky. Let the clouds occupy on the average a fraction p{sub cld} of the volume of the cloudy layer, and let them have a prescribed distribution of sizes about some mean. This is not a fractal distribution, because it has a scale. Cloud shape is unimportant so long as cloud aspect ratios are not far from unity. Take the single-scattering albedo to be unity for the droplets in the clouds. All of the absorption is due to atmospheric gases, so the absorption coefficient at a point is the same for cloud and clear sky. Absorption by droplets is less than 10% effect in the numerical stochastic radiation calculations described below, so it is reasonable to neglect it at this level of idealization.

  15. Sulfur K-edge absorption spectroscopy on selected biological systems

    International Nuclear Information System (INIS)

    Lichtenberg, Henning

    2008-07-01

    Sulfur is an essential element in organisms. In this thesis investigations of sulfur compounds in selected biological systems by XANES (X-ray Absorption Near Edge Structure) spectroscopy are reported. XANES spectroscopy at the sulfur K-edge provides an excellent tool to gain information about the local environments of sulfur atoms in intact biological samples - no extraction processes are required. Spatially resolved measurements using a Kirkpatrick-Baez mirror focusing system were carried out to investigate the infection of wheat leaves by rust fungi. The results give information about changes in the sulfur metabolism of the host induced by the parasite and about the extension of the infection into visibly uninfected plant tissue. Furthermore, XANES spectra of microbial mats from sulfidic caves were measured. These mats are dominated by microbial groups involved in cycling sulfur. Additionally, the influence of sulfate deprivation and H 2 S exposure on sulfur compounds in onion was investigated. To gain an insight into the thermal degradation of organic material the influence of roasting of sulfur compounds in coffee beans was studied. (orig.)

  16. FeS-Quantum-Dot Sensitized Metal Oxide Photoelectrodes: Photoelectrochemistry and Photoinduced Absorption Spectroscopy

    Directory of Open Access Journals (Sweden)

    Idriss Bedja

    2011-01-01

    Full Text Available TiO2, ZnO nanoparticulate(-np, and ZnO-nanorod(-nr electrodes have been modified with FeS2 (pyrite nanoparticles. Quantum size effect is manifested by a blue shift in both absorption and photocurrent action spectra. PIA (photoinduced absorption spectroscopy, a multipurpose tool in the study of dye-sensitized solar cells, is used to study quantum-dot modified metal oxide (MO nanostructured electrodes. The PIA spectra showed an evidence for long-lived photoinduced charge separation. Time-resolved PIA showed that recombination between electrons and holes occurs on a millisecond timescale. Incident-photon-to-current efficiencies at 400 nm are ranged between 13% and 25%. The better solar cell performance of FeS2 on ZnO-nr over ZnO-np can be ascribed to the faster, unidirectional e-transport channels through the ZnO-nr as well as the longer electron lifetimes. The lower performances of electrodes can be explained by the presence of FeS2 phases other than the photoactive pyrite phase, as evidenced from XRD study.

  17. Quantitative investigation of two metallohydrolases by X-ray absorption spectroscopy near-edge spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, W. [Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027 (China); Chu, W.S.; Yang, F.F.; Yu, M.J.; Chen, D.L.; Guo, X.Y. [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Zhou, D.W.; Shi, N. [Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027 (China); Marcelli, A. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, P.O. Box 13, Frascati 00044 (Italy); Niu, L.W.; Teng, M.K. [Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027 (China); Gong, W.M. [Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101 (China); Benfatto, M. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, P.O. Box 13, Frascati 00044 (Italy); Wu, Z.Y. [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, P.O. Box 13, Frascati 00044 (Italy)], E-mail: wuzy@ihep.ac.cn

    2007-09-21

    The last several years have witnessed a tremendous increase in biological applications using X-ray absorption spectroscopy (BioXAS), thanks to continuous advancements in synchrotron radiation (SR) sources and detector technology. However, XAS applications in many biological systems have been limited by the intrinsic limitations of the Extended X-ray Absorption Fine Structure (EXAFS) technique e.g., the lack of sensitivity to bond angles. As a consequence, the application of the X-ray absorption near-edge structure (XANES) spectroscopy changed this scenario that is now continuously changing with the introduction of the first quantitative XANES packages such as Minut XANES (MXAN). Here we present and discuss the XANES code MXAN, a novel XANES-fitting package that allows a quantitative analysis of experimental data applied to Zn K-edge spectra of two metalloproteins: Leptospira interrogans Peptide deformylase (LiPDF) and acutolysin-C, a representative of snake venom metalloproteinases (SVMPs) from Agkistrodon acutus venom. The analysis on these two metallohydrolases reveals that proteolytic activities are correlated to subtle conformation changes around the zinc ion. In particular, this quantitative study clarifies the occurrence of the LiPDF catalytic mechanism via a two-water-molecules model, whereas in the acutolysin-C we have observed a different proteolytic activity correlated to structural changes around the zinc ion induced by pH variations.

  18. Quantitative investigation of two metallohydrolases by X-ray absorption spectroscopy near-edge spectroscopy

    International Nuclear Information System (INIS)

    Zhao, W.; Chu, W.S.; Yang, F.F.; Yu, M.J.; Chen, D.L.; Guo, X.Y.; Zhou, D.W.; Shi, N.; Marcelli, A.; Niu, L.W.; Teng, M.K.; Gong, W.M.; Benfatto, M.; Wu, Z.Y.

    2007-01-01

    The last several years have witnessed a tremendous increase in biological applications using X-ray absorption spectroscopy (BioXAS), thanks to continuous advancements in synchrotron radiation (SR) sources and detector technology. However, XAS applications in many biological systems have been limited by the intrinsic limitations of the Extended X-ray Absorption Fine Structure (EXAFS) technique e.g., the lack of sensitivity to bond angles. As a consequence, the application of the X-ray absorption near-edge structure (XANES) spectroscopy changed this scenario that is now continuously changing with the introduction of the first quantitative XANES packages such as Minut XANES (MXAN). Here we present and discuss the XANES code MXAN, a novel XANES-fitting package that allows a quantitative analysis of experimental data applied to Zn K-edge spectra of two metalloproteins: Leptospira interrogans Peptide deformylase (LiPDF) and acutolysin-C, a representative of snake venom metalloproteinases (SVMPs) from Agkistrodon acutus venom. The analysis on these two metallohydrolases reveals that proteolytic activities are correlated to subtle conformation changes around the zinc ion. In particular, this quantitative study clarifies the occurrence of the LiPDF catalytic mechanism via a two-water-molecules model, whereas in the acutolysin-C we have observed a different proteolytic activity correlated to structural changes around the zinc ion induced by pH variations

  19. Collison-Induced Absorption of Oxygen Molecule as Studied by High Sensitivity Spectroscopy

    Science.gov (United States)

    Kashihara, Wataru; Shoji, Atsushi; Kawai, Akio

    2017-06-01

    Oxygen dimol is transiently generated when two oxygen molecules collide. At this short period, the electron clouds of molecules are distorted and some forbidden transition electronic transitions become partially allowed. This transition is called CIA (Collision-induced absorption). There are several CIA bands appearing in the spectral region from UV to near IR. Absorption of solar radiation by oxygen dimol is a small but significant part of the total budget of incoming shortwave radiation. However, a theory predicting the lineshape of CIA is still under developing. In this study, we measured CIA band around 630 nm that is assigned to optical transition, a^{1}Δ_{g}(v=0):a^{1}Δ_{g}(v=0)-X^{3}Σ_{g}^{-}(v=0):X^{3}Σ_{g}^{-}(v=0) of oxygen dimol. CRDS(Cavity Ring-down Spectroscopy) was employed to measure weak absorption CIA band of oxygen. Laser beam around 630 nm was generated by a dye laser that was pumped by a YAG Laser. Multiple reflection of the probe light was performed within a vacuum chamber that was equipped with two high reflective mirrors. We discuss the measured line shape of CIA on the basis of collision pair model.

  20. Indirect absorption spectroscopy using quantum cascade lasers: mid-infrared refractometry and photothermal spectroscopy.

    Science.gov (United States)

    Pfeifer, Marcel; Ruf, Alexander; Fischer, Peer

    2013-11-04

    We record vibrational spectra with two indirect schemes that depend on the real part of the index of refraction: mid-infrared refractometry and photothermal spectroscopy. In the former, a quantum cascade laser (QCL) spot is imaged to determine the angles of total internal reflection, which yields the absorption line via a beam profile analysis. In the photothermal measurements, a tunable QCL excites vibrational resonances of a molecular monolayer, which heats the surrounding medium and changes its refractive index. This is observed with a probe laser in the visible. Sub-monolayer sensitivities are demonstrated.

  1. Direct correlation of charge transfer absorption with molecular donor:acceptor interfacial area via photothermal deflection spectroscopy

    KAUST Repository

    Domingo, Ester

    2015-04-09

    We show that the Charge Transfer (CT) absorption signal in bulk-heterojunction (BHJ) solar cell blends, measured by photothermal deflection spectroscopy (PDS), is directly proportional to the density of molecular donor/acceptor interfaces. Since the optical transitions from ground state to the interfacial CT state are weakly allowed at photon energies below the optical gap of both donor and acceptor, we can exploit the use of this sensitive linear absorption spectroscopy for such quantification. Moreover, we determine the absolute molar extinction coefficient of the CT transition for an archetypical polymer-fullerene interface. The latter is ~100 times lower than the extinction coefficient of the donor chromophore involved, allowing us to experimentally estimate the transition dipole moment (0.3 D) and the electronic coupling between ground state and CT state to be on the order of 30 meV.

  2. A mathematical procedure to estimate solar absorptance of shallow water ponds

    International Nuclear Information System (INIS)

    Wu Hongbo; Tang Runsheng; Li Zhimin; Zhong Hao

    2009-01-01

    In this article, a mathematical procedure is developed for estimating solar absorption of shallow water ponds with different pond floor based on the fact that the solar radiation trapped inside the water layer undergoes multiplicative reflection and absorption and on that the solar absorption of water is selective. Theoretical model indicates that the solar absorption of a water pond is related to the reflectivity of the pond floor, the solar spectrum and the water depth. To validate the mathematical model, a concrete water pond measuring 3 x 3 x 0.24 m was constructed. Experimental results indicate that solar reflectivity calculated based on the mathematical model proposed in this work were in good agreement with those measured. For water ponds with a water-permeable floor, such as concrete floor, theoretical calculations of the solar absorptance of a water pond should be done based on the reflectivity of full wet floor, whereas for water ponds with a non-water-permeable floor, theoretical calculations should be done based on the fact that solar reflection on the floor is neither perfect specular reflection nor prefect isotropic diffuse reflection. Results of numerical calculation show that theoretical calculations of solar absorption of a water pond by dividing solar spectrum into six bands were pretty agreement with those by dividing solar spectrum into 20 bands.

  3. On the regularization for nonlinear tomographic absorption spectroscopy

    Science.gov (United States)

    Dai, Jinghang; Yu, Tao; Xu, Lijun; Cai, Weiwei

    2018-02-01

    Tomographic absorption spectroscopy (TAS) has attracted increased research efforts recently due to the development in both hardware and new imaging concepts such as nonlinear tomography and compressed sensing. Nonlinear TAS is one of the emerging modality that bases on the concept of nonlinear tomography and has been successfully demonstrated both numerically and experimentally. However, all the previous demonstrations were realized using only two orthogonal projections simply for ease of implementation. In this work, we examine the performance of nonlinear TAS using other beam arrangements and test the effectiveness of the beam optimization technique that has been developed for linear TAS. In addition, so far only smoothness prior has been adopted and applied in nonlinear TAS. Nevertheless, there are also other useful priors such as sparseness and model-based prior which have not been investigated yet. This work aims to show how these priors can be implemented and included in the reconstruction process. Regularization through Bayesian formulation will be introduced specifically for this purpose, and a method for the determination of a proper regularization factor will be proposed. The comparative studies performed with different beam arrangements and regularization schemes on a few representative phantoms suggest that the beam optimization method developed for linear TAS also works for the nonlinear counterpart and the regularization scheme should be selected properly according to the available a priori information under specific application scenarios so as to achieve the best reconstruction fidelity. Though this work is conducted under the context of nonlinear TAS, it can also provide useful insights for other tomographic modalities. © 2017 Elsevier Ltd.

  4. Photocurrent Spectroscopy of Perovskite Layers and Solar Cells: A Sensitive Probe of Material Degradation

    KAUST Repository

    Holovský, Jakub

    2017-01-25

    Optical absorptance spectroscopy of polycrystalline CHNHPbI films usually indicates the presence of a PbI phase, either as a preparation residue or due to film degradation, but gives no insight on how this may affect electrical properties. Here, we apply photocurrent spectroscopy to both perovskite solar cells and coplanar-contacted layers at various stages of degradation. In both cases, we find that the presence of a PbI phase restricts charge-carrier transport, suggesting that PbI encapsulates CHNHPbI grains. We also find that PbI injects holes into the CHNHPbI grains, increasing the apparent photosensitivity of PbI. This phenomenon, known as modulation doping, is absent in the photocurrent spectra of solar cells, where holes and electrons have to be collected in pairs. This interpretation provides insights into the photogeneration and carrier transport in dual-phase perovskites.

  5. Nanoimprint-Transfer-Patterned Solids Enhance Light Absorption in Colloidal Quantum Dot Solar Cells

    KAUST Repository

    Kim, Younghoon

    2017-03-13

    Colloidal quantum dot (CQD) materials are of interest in thin-film solar cells due to their size-tunable bandgap and low-cost solution-processing. However, CQD solar cells suffer from inefficient charge extraction over the film thicknesses required for complete absorption of solar light. Here we show a new strategy to enhance light absorption in CQD solar cells by nanostructuring the CQD film itself at the back interface. We use two-dimensional finite-difference time-domain (FDTD) simulations to study quantitatively the light absorption enhancement in nanostructured back interfaces in CQD solar cells. We implement this experimentally by demonstrating a nanoimprint-transfer-patterning (NTP) process for the fabrication of nanostructured CQD solids with highly ordered patterns. We show that this approach enables a boost in the power conversion efficiency in CQD solar cells primarily due to an increase in short-circuit current density as a result of enhanced absorption through light-trapping.

  6. Use of interfacial layers to prolong hole lifetimes in hematite probed by ultrafast transient absorption spectroscopy

    Science.gov (United States)

    Paradzah, Alexander T.; Diale, Mmantsae; Maabong, Kelebogile; Krüger, Tjaart P. J.

    2018-04-01

    Hematite is a widely investigated material for applications in solar water oxidation due primarily to its small bandgap. However, full realization of the material continues to be hampered by fast electron-hole recombination rates among other weaknesses such as low hole mobility, short hole diffusion length and low conductivity. To address the problem of fast electron-hole recombination, researchers have resorted to growth of nano-structured hematite, doping and use of under-layers. Under-layer materials enhance the photo-current by minimising electron-hole recombination through suppressing of back electron flow from the substrate, such as fluorine-doped tin oxide (FTO), to hematite. We have carried out ultrafast transient absorption spectroscopy on hematite in which Nb2O5 and SnO2 materials were used as interfacial layers to enhance hole lifetimes. The transient absorption data was fit with four different lifetimes ranging from a few hundred femtoseconds to a few nanoseconds. We show that the electron-hole recombination is slower in samples where interfacial layers are used than in pristine hematite. We also develop a model through target analysis to illustrate the effect of under-layers on electron-hole recombination rates in hematite thin films.

  7. Interferometric measurement of lines shift in flames in connection with interpretation of lined absorption method in atomic absorption spectroscopy

    International Nuclear Information System (INIS)

    L'vov, B.V.; Polzik, L.K.; Katskov, D.A.; Kruglikova, L.P.

    1975-01-01

    This paper is concerned with interferometric measuring of the line shift in flames in the view of interpretation of absorption lines in the atomic absorption spectroscopy. The newly measured line shifts were compared to the known data on Lorentz broadening of the same lines obtained by methods free of the systematic errors. The resonant lines of the alkaline earth elements (Sr, Ca, Ba) were investigated. To reduce self-absorption in the flame the solutions with minimum concentrations of the elements were used. The computation scheme includes the spectrometer apparatus width and line broadening due to the self-absorption. Formulae are given for computing the values studied. Good agreement was observed between the computed and experimental results. Error analysis was performed. It was concluded that any line shifts in the hydrocarbons were correctly taken into an account in the absolute computations of absorption

  8. Evidence for the presence of the 802.7/cm band Q branch of HO2NO2 in high resolution solar absorption spectra of the stratosphere

    Science.gov (United States)

    Rinsland, C. P.; Zander, R.; Farmer, C. B.; Norton, R. H.; Brown, L. R.; Russell, J. M., III; Park, J. H.

    1986-08-01

    Stratospheric solar absorption spectra recorded at ≡0.01 cm-1 resolution by the ATMOS (Atmospheric Trace Molecule Spectroscopy) Fourier transform spectrometer during the Spacelab 3 Shuttle mission show a weak absorption feature covering ≡802.5 - 803.3 cm-1. The authors identify this feature as the unresolved Q branch of the 802.7 cm-1 band of HO2NO2 and report profiles for 31°N and 47°S.

  9. Compensation of self-absorption losses in luminescent solar concentrators by increasing luminophore concentration

    NARCIS (Netherlands)

    Krumer, Zachar; van Sark, Wilfried G.J.H.M.; Schropp, Ruud E.I.; de Mello Donegá, Celso

    2017-01-01

    Self-absorption in luminophores is considered a major obstacle on the way towards efficient luminescent solar concentrators (LSCs). It is commonly expected that upon increasing luminophore concentration in an LSC the absorption of the luminophores increases as well and therefore self-absorption

  10. Infrared absorption spectroscopy and chemical kinetics of free radicals

    International Nuclear Information System (INIS)

    Curl, R.F.; Glass, G.P.

    1991-01-01

    A new channel producing ketenyl radical (HCCO) was discovered in the flash photolysis of ketene at 193 nm. H 2 CCO + hν(193 nm) → H + HCCO by observation near 2020 cm -1 of the infrared fundamental of ketenyl corresponding to the antisymmetric motion of the heavy atoms. This band has been partially rotationally analyzed and the rate constant for the reaction of ketenyl with NO has been determined. The OH stretching fundamental of hydroxymethyl radical (CH 2 OH) has been observed near 3600 cm -1 producing the radical either by the excimer flash photolysis of acetol (CH 3 COCH 2 OH) or by Cl atom abstraction of a methyl hydrogen from methanol. The assignment of the spectrum to CH 2 OH was confirmed by the agreement of the rate constant for the reaction of the species with O 2 with the literature value. The mechanism of the reaction of C 2 H with O 2 has been explored. There appear to be two channels producing CO product: a fast, direct one producing highly vibrationally excited CO up to v = 6 at the same rate C 2 H disappears and a slow, indirect one producing primarily ground state CO on a much longer timescale than the disappearance of C 2 H. The rate constants for the reactions of C 2 H with CH 4 , C 2 H 6 , C 2 H 4 , D 2 , and CO were determined by following the time decay of a C 2 H infrared transient absorption line originating from the ground vibronic state using diode laser spectroscopy creating the C 2 H by excimer laser flash photolysis (ArF, 193 nm) of CF 3 CCH. The branching ratio into OH of the reaction between NH 2 , and NO, which is the channel thought to propagate the radical chain of the Thermal deNOx process, has been measured up to 925 degree C. The OH yield thus obtained appears to be too small to maintain the process. 5 refs., 3 figs

  11. Utilization of synchrotron radiation in analytical chemistry. Soft X-ray emission and absorption spectroscopy

    International Nuclear Information System (INIS)

    Muramatsu, Yasuji

    2015-01-01

    Synchrotron soft X-ray spectroscopy includes three major types of spectroscopy such as X-ray absorption spectroscopy (XAS), X-ray emission spectroscopy (XES), and X-ray photoelectron spectroscopy (XPS). This paper takes up XAS and XES of soft X-rays, and briefly describes the principle. XAS is roughly classified into XANES (X-ray absorption near-edge structure) and EXAFS (extended X-ray absorption fine structure), and XANES is mainly used in the analysis based on XAS of soft X-rays. As the examples of the latest soft X-ray analyses, the following are introduced: (1) bandgap of boron implantation diamond and the local structure of boron, (2) catalytic sites in solid fuel cell carbon electrode, and (3) soft X-ray analysis under atmospheric pressure. (A.O.)

  12. Intracavity absorption spectroscopy of formaldehyde from 6230 to 6420 cm(-1)

    NARCIS (Netherlands)

    Fjodorow, Peter; Hellmig, Ortwin; Baev, Valery M.; Levinsky, Howard B.; Mokhov, Anatoli V.

    We apply intracavity absorption spectroscopy for measurements of the absorption spectrum of formaldehyde, CH2O, from 6230 to 6420 cm(-1), of which only a small fraction (6351-6362 cm(-1)) has been recorded elsewhere. The measurements are performed in the cavity of a broadband Er3+-doped fiber laser,

  13. Femtosecond X-ray Absorption Spectroscopy at a Hard X-ray Free Electron Laser

    DEFF Research Database (Denmark)

    Lemke, Henrik T.; Bressler, Christian; Chen, Lin X.

    2013-01-01

    -quality X-ray absorption data and we report femtosecond time-resolved X-ray absorption near-edge spectroscopy (XANES) measurements of a spin-crossover system, iron(II) tris(2,2'-bipyridine) in water. The data indicate that the low-spin to high-spin transition can be modeled by single-exponential kinetics...

  14. High-Resolution X-ray Emission and X-ray Absorption Spectroscopy

    NARCIS (Netherlands)

    Groot, F.M.F. de

    2000-01-01

    In this review, high-resolution X-ray emission and X-ray absorption spectroscopy will be discussed. The focus is on the 3d transition-metal systems. To understand high-resolution X-ray emission and reso-nant X-ray emission, it is first necessary to spend some time discussing the X-ray absorption

  15. Modification of UV absorption profile of polymer film reflectors to increase solar-weighted reflectance

    Science.gov (United States)

    Jorgensen, Gary; Gee, Randall C.; White, David

    2017-05-02

    Provided are reflective thin film constructions including a reduced number of layers, which provides for increased solar-weighted hemispherical reflectance and durability. Reflective films include those comprising an ultraviolet absorbing abrasion resistant coating over a metal layer. Also provided are ultraviolet absorbing abrasion resistant coatings and methods for optimizing the ultraviolet absorption of an abrasion resistant coating. Reflective films disclosed herein are useful for solar reflecting, solar collecting, and solar concentrating applications, such as for the generation of electrical power.

  16. Comparative Investigation of the Efficiency of Absorption of Solar Energy by Carbon Composite Materials

    Science.gov (United States)

    Prikhod‧ko, N. G.; Smagulova, G. T.; Rakhymzhan, N. B.; Kim, S.; Lesbaev, B. T.; Nazhipkyzy, M.; Mansurov, Z. A.

    2017-01-01

    This paper presents the results of research on the efficiency of absorption of solar energy by various carbon materials (soot, carbonized apricot pits and rice husks, and carbon nanotubes in the form of a ″forest″), as well as by composites based on them with inclusions of metal oxide nanoparticles. An analysis of the efficiency of absorption of solar energy by various carbon materials has demonstrated the advantage of the carbon material from carbonized apricot pits. The results of the comparative investigation of the absorptivity of apricot pits with that of the coating of a production prototype of solar collector are presented.

  17. F K-edge soft X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Sugimura, Tetsuro; Kawai, Jun; Maeda, Kuniko; Fukushima, Akiko; Shin, S.; Motoyama, Muneyuki; Nakajima Tsuyoshi

    2001-01-01

    We measured F X-ray absorption spectra of various fluorine compounds using a synchrotron radiation at KEK-PF. The absorption spectra were measured using X-ray fluorescence yield (XFY) and total electron yield (TEY) methods. Change of the spectral shape has a relation to the metal-fluorine bond distance. By comparing with the experimental spectrum and calculated spectrum, F 2p state density is divined into up and down states. (author)

  18. Ultrafast terahertz conductivity and transient optical absorption spectroscopy of silicon nanocrystal thin films

    DEFF Research Database (Denmark)

    Titova, Lyubov V.; Harthy, Rahma Al; Cooke, David

    We use time-resolved THz spectroscopy and transient optical absorption spectroscopy as two complementary techniques to study ultrafast carrier dynamics in silicon nanocrystal thin films. We find that the photoconductive dynamics in these materials is dominated by interface trapping, and we observ...

  19. Remote Laser Evaporative Molecular Absorption Spectroscopy Sensor System

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose a sensor system capable of remotely probing the molecular composition of cold solar system targets (asteroids, comets, planets, moons), such as from a...

  20. Feasibility and Basic Design of Solar Integrated Absorption Refrigeration for an Industry

    KAUST Repository

    Akhtar, Saad

    2015-08-28

    This paper presents a review of existing solar cooling technologies and a feasibility study of a solar absorption cooling system for a packaging facility at Tetrapak Lahore, Pakistan. The review includes brief description of existing chiller technologies and solar collectors. The case study includes analysis of the solar potential and design of the cooling system at considered site. The design calculations upon which the feasibility analysis is carried out are solar collector area and type, cooling capacity, cooling area. A comparison is made between solar cooling potential of Pakistan and existing sites all across the globe. Finally an economic analysis is carried out to demonstrate the financial viability of the new cooling system.

  1. Total Absorption Spectroscopy study of the 152Yb decay

    International Nuclear Information System (INIS)

    Estevez, M.E.; Algora, A.; Rubio, B.; Bernabeu, J.; Nacher, E.; Gadea, A.; Tain, J.L.; Cano, D.; Batist, L.; Burkard, K.

    2008-01-01

    Complete text of publication follows. The study of neutrino oscillation phenomena, which could open the possibility for Charge Conjugation-Parity violation in the lepton sector, is one of the most exciting problems in physics. In the appearance probability for neutrino oscillations, the CP-even terms and the CP-odd terms have different energy dependence, so the control of the neutrino beam energy has an added value. To study these topics, the construction of a monochromatic neutrino beam facility has been proposed recently. As a source for this beam, accelerated nuclei that decay through electron capture (EC) in a storage ring with long straight sections could be used. In a recent annual report, a preliminary study of the candidate nucleus 152 Yb was discussed. In this report we present the results of the Total Absorption Spectroscopy (TAS) analysis of these data. In the analysis, a coincidence between the X ray of 152 Tm (produced in the EC process) and the TAS spectrum is required. In the gated TAS spectrum the peaks are identified with levels fed in the decay, but it can also have contributions from contaminants and background, and it is modified by the detector response. The relation between the gated TAS spectrum and the feeding is: di = Σ j=1 jmax R ij f j , where d i is the number of counts in channel i of the measured spectrum, f j is the feeding to level j, and R ij is the probability that feeding to E j , gives counts on channel i of the measured spectrum. R is called the 'Response Function' of the detector, and depends on the decay scheme and on the detector. It was calculated by means of Montecarlo simulations. The problem of finding the feedings is reduced to solve this equation, for which the 'Expectation- Maximization Method' was used. It was shown that this algorithm is a very effective way to solve the TAS inverse problem. It is known that in some cases, the high resolution (HR) technique assigns incorrectly more feeding to low lying energy levels

  2. Spectral studies of ocean water with space-borne sensor SCIAMACHY using Differential Optical Absorption Spectroscopy (DOAS

    Directory of Open Access Journals (Sweden)

    M. Vountas

    2007-09-01

    Full Text Available Methods enabling the retrieval of oceanic parameter from the space borne instrumentation Scanning Imaging Absorption Spectrometer for Atmospheric ChartographY (SCIAMACHY using Differential Optical Absorption Spectroscopy (DOAS are presented. SCIAMACHY onboard ENVISAT measures back scattered solar radiation at a spectral resolution (0.2 to 1.5 nm. The DOAS method was used for the first time to fit modelled Vibrational Raman Scattering (VRS in liquid water and in situ measured phytoplankton absorption reference spectra to optical depths measured by SCIAMACHY. Spectral structures of VRS and phytoplankton absorption were clearly found in these optical depths. Both fitting approaches lead to consistent results. DOAS fits correlate with estimates of chlorophyll concentrations: low fit factors for VRS retrievals correspond to large chlorophyll concentrations and vice versa; large fit factors for phytoplankton absorption correspond with high chlorophyll concentrations and vice versa. From these results a simple retrieval technique taking advantage of both measurements is shown. First maps of global chlorophyll concentrations were compared to the corresponding MODIS measurements with very promising results. In addition, results from this study will be used to improve atmospheric trace gas DOAS-retrievals from visible wavelengths by including these oceanographic signatures.

  3. Theoretical experimental study of the factors that govern the molybdenum absorption signal by means of electro thermic atomic absorption spectroscopy

    International Nuclear Information System (INIS)

    Garaboto Farfan, M. A.

    1996-01-01

    The formation of molybdenum carbides in the atomizer, used in the electro thermic atomic absorption spectroscopy, is responsible for incomplete analyte removal in its analysis. This generates the apparition of the memory effect and little precision in the results. In this work, different variables that could affect the molybdenum absorption sign were investigated, as well as the influence of hydrochloric acid on the memory effect, by means of studies in the different stages: drying, calcination and atomization, and the samples deposition order in molybdenum solutions, either acidified or not acidified [es

  4. Transient absorption spectroscopy studies on polythiophene-fullerene bulk heterojunction organic blend films sensitized with a low-bandgap polymer.

    Science.gov (United States)

    Löslein, Heiko; Ameri, Tayebeh; Matt, Gebhard J; Koppe, Markus; Egelhaaf, Hans J; Troeger, Anna; Sgobba, Vito; Guldi, Dirk M; Brabec, Christoph J

    2013-07-12

    Recently, the concept of near-infrared sensitization is successfully employed to increase the light harvesting in large-bandgap polymer-based solar cells. To gain deeper insights into the operation mechanism of ternary organic solar cells, a comprehensive understanding of charge transfer-charge transport in ternary blends is a necessity. Herein, P3HT:PCPDTBT:PCBM ternary blend films are investigated by transient absorption spectroscopy. Hole transfer from PCPDTBT-positive polarons to P3HT in the P3HT:PCPDTBT:PCBM 0.9:0.1:1 blend film can be visualized. This process evolves within 140 ps and is discussed with respect to the proposed charge-generation mechanisms. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Impedance spectroscopy on polymer-fullerene solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Knipper, M.; Parisi, J. [Oldenburg Univ. (Germany). Energy and Semiconductor Research Lab.; Coakley, K.; Waldauf, C.; Brabec, C.J. [Konarka Technologies Germany, Nuernberg (Germany); Dyakonov, V. [Wuerzburg Univ. (Germany). Faculty of Physics and Astronomy

    2007-09-15

    Impedance spectroscopy is used for studying the electrical transport properties of bulk heterojunction solar cells. A replacement circuit is needed to translate the frequency response of the circuit to the individual interfaces and layers of the solar cell. As a material combination and device architecture, composites of P3HT and PCBM, sandwiched between a transparent ITO front electrode and an aluminum back electrode, as well as a polymer buffer layer were investigated. By varying the film thickness we identified an equivalent circuit capable to fit our experimental data. We found a dielectric constant for the P3HT and for the P3HT:PCBM bulk. (orig.)

  6. Method and apparatus for aerosol particle absorption spectroscopy

    Science.gov (United States)

    Campillo, Anthony J.; Lin, Horn-Bond

    1983-11-15

    A method and apparatus for determining the absorption spectra, and other properties, of aerosol particles. A heating beam source provides a beam of electromagnetic energy which is scanned through the region of the spectrum which is of interest. Particles exposed to the heating beam which have absorption bands within the band width of the heating beam absorb energy from the beam. The particles are also illuminated by light of a wave length such that the light is scattered by the particles. The absorption spectra of the particles can thus be determined from an analysis of the scattered light since the absorption of energy by the particles will affect the way the light is scattered. Preferably the heating beam is modulated to simplify the analysis of the scattered light. In one embodiment the heating beam is intensity modulated so that the scattered light will also be intensity modulated when the particles absorb energy. In another embodiment the heating beam passes through an interferometer and the scattered light reflects the Fourier Transform of the absorption spectra.

  7. Force-detected nanoscale absorption spectroscopy in water at room temperature using an optical trap

    Science.gov (United States)

    Parobek, Alexander; Black, Jacob W.; Kamenetska, Maria; Ganim, Ziad

    2018-04-01

    Measuring absorption spectra of single molecules presents a fundamental challenge for standard transmission-based instruments because of the inherently low signal relative to the large background of the excitation source. Here we demonstrate a new approach for performing absorption spectroscopy in solution using a force measurement to read out optical excitation at the nanoscale. The photoinduced force between model chromophores and an optically trapped gold nanoshell has been measured in water at room temperature. This photoinduced force is characterized as a function of wavelength to yield the force spectrum, which is shown to be correlated to the absorption spectrum for four model systems. The instrument constructed for these measurements combines an optical tweezer with frequency domain absorption spectroscopy over the 400-800 nm range. These measurements provide proof-of-principle experiments for force-detected nanoscale spectroscopies that operate under ambient chemical conditions.

  8. Characterization of Nanocrystalline SiGe Thin Film Solar Cell with Double Graded-Dead Absorption Layer

    Directory of Open Access Journals (Sweden)

    Chao-Chun Wang

    2012-01-01

    Full Text Available The nanocrystalline silicon-germanium (nc-SiGe thin films were deposited by high-frequency (27.12 MHz plasma-enhanced chemical vapor deposition (HF-PECVD. The films were used in a silicon-based thin film solar cell with graded-dead absorption layer. The characterization of the nc-SiGe films are analyzed by scanning electron microscopy, UV-visible spectroscopy, and Fourier transform infrared absorption spectroscopy. The band gap of SiGe alloy can be adjusted between 0.8 and 1.7 eV by varying the gas ratio. For thin film solar cell application, using double graded-dead i-SiGe layers mainly leads to an increase in short-circuit current and therefore cell conversion efficiency. An initial conversion efficiency of 5.06% and the stabilized efficiency of 4.63% for an nc-SiGe solar cell were achieved.

  9. Structural study of aggregated β-carotene by absorption spectroscopy

    Science.gov (United States)

    Lu, Li Ping; Wei, Liang Shu

    2017-10-01

    By UV-visible absorption spectroscope, the aggregated β-carotene in hydrated ethanol was studied in the temperature range of 5 55°C, with different ethanol/water ratio. And the structural evolutions of these aggregates with time were detected. The spectrophotometric analysis showed that the aggregate of β-carotene formed in 1:1 ethanol/water solution transfered from H-type to J-type with temperature increase. In 2:1 ethanol/water solution a new type of aggregate with strong coupling was predicated by the appearing absorption peak located at about 550 nm. In the time scales of 48 houses all the aggregated structures were stable, but the absorption intensity decreased with time. It was concluded that the types of aggregated β-carotene which wouldn't change with time depended on the solvent composition and temperature.

  10. Precision spectroscopy with a frequency-comb-calibrated solar spectrograph

    Science.gov (United States)

    Doerr, H.-P.

    2015-06-01

    The measurement of the velocity field of the plasma at the solar surface is a standard diagnostic tool in observational solar physics. Detailed information about the energy transport as well as on the stratification of temperature, pressure and magnetic fields in the solar atmosphere are encoded in Doppler shifts and in the precise shape of the spectral lines. The available instruments deliver data of excellent quality and precision. However, absolute wavelength calibration in solar spectroscopy was so far mostly limited to indirect methods and in general suffers from large systematic uncertainties of the order of 100 m/s. During the course of this thesis, a novel wavelength calibration system based on a laser frequency comb was deployed to the solar Vacuum Tower Telescope (VTT), Tenerife, with the goal of enabling highly accurate solar wavelength measurements at the level of 1 m/s on an absolute scale. The frequency comb was developed in a collaboration between the Kiepenheuer-Institute for Solar Physics, Freiburg, Germany and the Max Planck Institute for Quantum Optics, Garching, Germany. The efforts cumulated in the new prototype instrument LARS (Lars is an Absolute Reference Spectrograph) for solar precision spectroscopy which is in preliminary scientific operation since~2013. The instrument is based on the high-resolution echelle spectrograph of the VTT for which feed optics based on single-mode optical fibres were developed for this project. The setup routinely achieves an absolute calibration accuracy of 60 cm/s and a repeatability of 2.5 cm/s. An unprecedented repeatability of only 0.32 cm/s could be demonstrated with a differential calibration scheme. In combination with the high spectral resolving power of the spectrograph of 7x10^5 and virtually absent internal scattered light, LARS provides a spectral purity and fidelity that previously was the domain of Fourier-transform spectrometers only. The instrument therefore provides unique capabilities for

  11. In situ gas temperature measurements by UV-absorption spectroscopy

    DEFF Research Database (Denmark)

    Fateev, Alexander; Clausen, Sønnik

    2009-01-01

    The absorption spectrum of the NO A(2)Sigma(+) <- X(2)Pi gamma-system can be used for in situ evaluation of gas temperature. Experiments were performed with a newly developed atmospheric-pressure high-temperature flow gas cell at highly uniform and stable gas temperatures over a 0.533 m path in t....... The accuracy of both methods is discussed. Validation of the classical Lambert-Beer law has been demonstrated at NO concentrations up to 500 ppm and gas temperatures up to 1,500 degrees C over an optical absorption path length of 0.533 m....

  12. Optical absorption spectroscopy of natural and irradiated pink tourmaline

    International Nuclear Information System (INIS)

    Camargo, M.B.; Isotani, S.

    1985-01-01

    The Brazilian natural pink tourmaline is studied through the polarized optical absorption measurements. The effect of increasing doses of γ-rays from 60 Co in the spectra were determined (maximum of 20MGy). The following optical absorption bands were observed: 8,500 and 14,800 cm -1 assigned to d-d transitions of Fe 2+ in b- and c-sites, respectively; 19,500 and 25,500 cm -1 assigned to 5 E → 5 A 1 and 5 B 2 → 5 A 1 d-d transitions of Mn 3+ , respectively. (Author) [pt

  13. Measurement of atmospheric precipitable water using a solar radiometer. [water vapor absorption effects

    Science.gov (United States)

    Pitts, D. E.; Dillinger, A. E.; Mcallum, W. E.

    1974-01-01

    A technique is described and tested that allows the determination of atmospheric precipitable water from two measurements of solar intensity: one in a water-vapor absorption band and another in a nearby spectral region unaffected by water vapor.

  14. Structure and dynamics in liquid water from x-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Wernet, Philippe

    2009-01-01

    Oxygen K-edge x-ray absorption spectra of water are discussed. The spectra of gas-phase water, liquid water and ice illustrate the sensitivity of oxygen K-edge x-ray absorption spectroscopy to hydrogen bonding in water. Transmission mode spectra of amorphous and crystalline ice are compared to x-ray Raman spectra of ice. The good agreement consolidates the experimental spectrum of crystalline ice and represents an incentive for theoretical calculations of the oxygen K-edge absorption spectrum of crystalline ice. Time-resolved infrared-pump and x-ray absorption probe results are finally discussed in the light of this structural interpretation.

  15. X-ray absorption spectroscopy: EXAFS [Extended X-ray Absorption Fine Structure] and XANES [X-ray Absorption Near Edge Structure

    International Nuclear Information System (INIS)

    Alp, E.E.; Mini, S.M.; Ramanathan, M.

    1990-04-01

    The x-ray absorption spectroscopy (XAS) had been an essential tool to gather spectroscopic information about atomic energy level structure in the early decades of this century. It has also played an important role in the discovery and systematization of rare-earth elements. The discovery of synchrotron radiation in 1952, and later the availability of broadly tunable synchrotron based x-ray sources have revitalized this technique since the 1970's. The correct interpretation of the oscillatory structure in the x-ray absorption cross-section above the absorption edge by Sayers et. al. has transformed XAS from a spectroscopic tool to a structural technique. EXAFS (Extended X-ray Absorption Fine Structure) yields information about the interatomic distances, near neighbor coordination numbers, and lattice dynamics. An excellent description of the principles and data analysis techniques of EXAFS is given by Teo. XANES (X-ray Absorption Near Edge Structure), on the other hand, gives information about the valence state, energy bandwidth and bond angles. Today, there are about 50 experimental stations in various synchrotrons around the world dedicated to collecting x-ray absorption data from the bulk and surfaces of solids and liquids. In this chapter, we will give the basic principles of XAS, explain the information content of essentially two different aspects of the absorption process leading to EXAFS and XANES, and discuss the source and samples limitations

  16. Enhanced light absorption in an ultrathin silicon solar cell utilizing plasmonic nanostructures

    DEFF Research Database (Denmark)

    Xiao, Sanshui; Mortensen, N. Asger

    2012-01-01

    Nowadays, bringing photovoltaics to the market is mainly limited by high cost of electricity produced by the photovoltaic solar cell. Thin-film photovoltaics offers the potential for a significant cost reduction compared to traditional photovoltaics. However, the performance of thin-film solar...... cells is generally limited by poor light absorption. We propose an ultrathin-film silicon solar cell configuration based on SOI structure, where the light absorption is enhanced by use of plasmonic nanostructures. By placing a one-dimensional plasmonic nanograting on the bottom of the solar cell......, the generated photocurrent for a 200 nm-thickness crystalline silicon solar cell can be enhanced by 90% in the considered wavelength range. These results are paving a promising way for the realization of high-efficiency thin-film solar cells....

  17. A parameterization for the absorption of solar radiation by water vapor in the earth's atmosphere

    Science.gov (United States)

    Wang, W.-C.

    1976-01-01

    A parameterization for the absorption of solar radiation as a function of the amount of water vapor in the earth's atmosphere is obtained. Absorption computations are based on the Goody band model and the near-infrared absorption band data of Ludwig et al. A two-parameter Curtis-Godson approximation is used to treat the inhomogeneous atmosphere. Heating rates based on a frequently used one-parameter pressure-scaling approximation are also discussed and compared with the present parameterization.

  18. Nanoscale dimples for improved absorption in organic solar cells

    DEFF Research Database (Denmark)

    Goszczak, Arkadiusz Jaroslaw; Rubahn, Horst-Günter; Madsen, Morten

    Organic solar cells (OSC’s) have attracted much attention in the past years due to their potential low-cost, light-weight and mechanical flexibility. A method for improving the power conversion efficiencies of the devices is by incorporating structured electrodes in the solar cell architecture, a...... ordered and discorded dimple arrangement and their contribution to light management is presented. Such dimples can later be employed to fabricate nanostructured electrodes in P3HT/PCBM organic solar cells....

  19. Surface enhanced infrared absorption spectroscopy for graphene functionalization on copper

    Czech Academy of Sciences Publication Activity Database

    Matulková, I.; Kovaříček, Petr; Šlouf, Miroslav; Němec, I.; Kalbáč, Martin

    2017-01-01

    Roč. 124, NOV 2017 (2017), s. 250-255 ISSN 0008-6223 R&D Projects: GA ČR(CZ) GA15-01953S; GA MŠk LL1301; GA MŠk(CZ) LM2015073 Grant - others:AVČR PPPLZ(CZ) L200401551; GA MŠk(CZ) CZ.02.1.01/0.0/0.0/16_013/0001821 Institutional support: RVO:61388955 ; RVO:61389013 Keywords : chemical-vapor-deposition * diazonium salts * raman-spectroscopy * covalent functionalization * seira spectroscopy * grown graphene Subject RIV: CF - Physical ; Theoretical Chemistry; CD - Macromolecular Chemistry (UMCH-V) OBOR OECD: Physical chemistry; Polymer science (UMCH-V) Impact factor: 6.337, year: 2016

  20. Surface enhanced infrared absorption spectroscopy for graphene functionalization on copper

    Czech Academy of Sciences Publication Activity Database

    Matulková, I.; Kovaříček, Petr; Šlouf, Miroslav; Němec, I.; Kalbáč, Martin

    2017-01-01

    Roč. 124, NOV 2017 (2017), s. 250-255 ISSN 0008-6223 R&D Projects: GA ČR(CZ) GA15-01953S; GA MŠk LL1301; GA MŠk(CZ) LM2015073 Grant - others:AVČR PPPLZ(CZ) L200401551; GA MŠk(CZ) CZ.02.1.01/0.0/0.0/16_013/0001821 Institutional support: RVO:61388955 ; RVO:61389013 Keywords : chemical -vapor-deposition * diazonium salts * raman-spectroscopy * covalent functionalization * seira spectroscopy * grown graphene Subject RIV: CF - Physical ; Theoretical Chemistry; CD - Macromolecular Chemistry (UMCH-V) OBOR OECD: Physical chemistry; Polymer science (UMCH-V) Impact factor: 6.337, year: 2016

  1. The statistical dependence of auroral absorption on geomagnetic and solar wind parameters

    Directory of Open Access Journals (Sweden)

    A. J. Kavanagh

    2004-03-01

    Full Text Available Data from the Imaging Riometer for Ionospheric Studies (IRIS at Kilpisjärvi, Finland, have been compiled to form statistics of auroral absorption based on seven years of observations. In a previous study a linear relationship between the logarithm of the absorption and the Kp index provided a link between the observations of precipitation with the level of geomagnetic activity. A better fit to the absorption data is found in the form of a quadratic in Kp for eight magnetic local time sectors. Past statistical investigations of absorption have hinted at the possibility of using the solar wind velocity as a proxy for the auroral absorption, although the lack of available satellite data made such an investigation difficult. Here we employ data from the solar wind monitors, WIND and ACE, and derive a linear relationship between the solar wind velocity and the cosmic noise absorption at IRIS for the same eight magnetic local time sectors. As far as the authors are aware this is the first time that in situ measurements of the solar wind velocity have been used to create a direct link with absorption on a statistical basis. The results are promising although, it is clear that some other factor is necessary in providing reliable absorption predictions. Due to the substorm related nature of auroral absorption, this is likely formed by the recent time history of the geomagnetic activity, or by some other indicator of the energy stored within the magnetotail. For example, a dependence on the southward IMF (interplanetary magnetic field is demonstrated with absorption increasing with successive decreases in Bz; a northward IMF appears to have little effect and neither does the eastward component, By.

    Key words. Magnetospheric physics (energetic particles, precipitating; solar wind-magnetosphere interactions – Ionosphere (modeling and forecasting

  2. Ternary blend of conjugated polymers for broadening the absorption bandwidth of polymer solar cells

    OpenAIRE

    Benten, Hiroaki; Nishida, Takaya; Mori, Daisuke; Ohkita, Hideo; Ito, Shinzaburo

    2016-01-01

    Ternary blend all-polymer solar cells are developed to broaden the absorption bandwidth of the photoactive layer. A wide-bandgap polymer with absorption in the visible region is introduced as a third polymer into a low-bandgap donor/acceptor binary polymer blend showing absorption in the near-infrared (NIR) region. In the ternary blend solar cell, the external quantum efficiency (EQE) is improved in the visible wavelength region, while retaining the excellent EQE of the host binary blend in t...

  3. INVESTIGATION OF SOLAR ABSORPTANCE OF BUILDING EXTERNAL SURFACES FROM HEAT FLUX POINT OF VIEW

    Directory of Open Access Journals (Sweden)

    Meral ÖZEL

    2006-02-01

    Full Text Available In this study, solar absorptance of external surfaces of buildings has been numerically investigated from the heat gain and losses point of view. For this purpose, external surface solar absorptance was icreased from 0 to 1with an ratio of 0.1 and, for the summer and winter conditions, heat fluxs was calculated by considering orientations of the wall and its roof for brick and concrete structure materials. Besides, external surface absorptance was assumed as 0.2, 0.5 and 0.9, respectively. Than, heat gain and losses were calculated to insulation thickness increasing on the outdoor surface of wall. Results obtained were presented as graphics

  4. Optical Absorption Spectroscopy for Gas Analysis in Biomass Gasification

    DEFF Research Database (Denmark)

    Grosch, Helge

    important gas species of the low-temperature circulating fluidized bed gasifier. At first, a special gas cell,the hot gas flow cell (HGC), was build up and veried. In this custom-made gas cell, the optical properties, the so-called absorption cross-sections, of the most important sulfur and aromatic...... compounds were determined in laboratory experiments. By means of the laboratory results and spectroscopic databases,the concentrations of the major gas species and the aromatic compounds phenol and naphthalene were determined in extraction and in-situ measurements....

  5. A GAS TEMPERATURE PROFILE BY INFRARED EMISSION-ABSORPTION SPECTROSCOPY

    Science.gov (United States)

    Buchele, D. R.

    1994-01-01

    This computer program calculates the temperature profile of a flame or hot gas. Emphasis is on profiles found in jet engine or rocket engine exhaust streams containing water vapor or carbon dioxide as radiating gases. The temperature profile is assumed to be axisymmetric with a functional form controlled by two variable parameters. The parameters are calculated using measurements of gas radiation at two wavelengths in the infrared spectrum. Infrared emission and absorption measurements at two or more wavelengths provide a method of determining a gas temperature profile along a path through the gas by using a radiation source and receiver located outside the gas stream being measured. This permits simplified spectral scanning of a jet or rocket engine exhaust stream with the instrumentation outside the exhaust gas stream. This program provides an iterative-cyclic computation in which an initial assumed temperature profile is altered in shape until the computed emission and absorption agree, within specified limits, with the actual instrument measurements of emission and absorption. Temperature determination by experimental measurements of emission and absorption at two or more wavelengths is also provided by this program. Additionally, the program provides a technique for selecting the wavelengths to be used for determining the temperature profiles prior to the beginning of the experiment. By using this program feature, the experimenter has a higher probability of selecting wavelengths which will result in accurate temperature profile measurements. This program provides the user with a technique for determining whether this program will be sufficiently accurate for his particular application, as well as providing a means of finding the solution. The input to the program consists of four types of data: (1) computer program control constants, (2) measurements of gas radiance and transmittance at selected wavelengths, (3) tabulations from the literature of gas

  6. Characterization of Metalloproteins and Biomaterials by X-ray Absorption Spectroscopy and X-ray Diffraction

    DEFF Research Database (Denmark)

    Frankær, Christian Grundahl

    by estimation of the water content by thermogravimetric analysis. Bone tissue from dogs treated with strontiummalonate was studied using XAS. A new approach for analysing the X-ray absorption spectra resulted in a compositional model, from which the relative distribution of strontium in the different bone......-ray crystallography and X-ray absorption spectroscopy (XAS) applied to studying different hexameric insulin conformations. (iii) The structures of polymorphs of strontium ranelate and the distribution of strontium in bone tissue. A procedure for fast identification and verification of protein powders using XRPD...... and R6) were solved by single crystal X-ray diffraction (XRD) to 1.40 Å, 1.30 Å and 1.80 Å resolution, respectively. The zinc coordination in each conformation was studied by XAS including both extended X-ray absorption fine structure (EXAFS) spectroscopy and X-ray absorption near edge structure (XANES...

  7. Ammonia absorption in calcium graphite intercalation compound: in situ neutron diffraction, Raman spectroscopy and magnetization.

    Science.gov (United States)

    Srinivas, G; Lovell, A; Skipper, N T; Bennington, S M; Kurban, Z; Smith, R I

    2010-06-21

    The structure and superconducting properties of ammoniated calcium-graphite intercalation compound (Ca-GIC) have been investigated using in situ time-of-flight neutron diffraction, Raman spectroscopy and magnetization studies. Ammonia absorption has been carried out by exposing preformed Ca-GIC to ammonia vapour at various pressures. Our in situ neutron diffraction data reveal a complex ammonia pressure dependent structural transformation, in which the growth of secondary ammoniated Ca-GIC phases are observed at the expense of the pristine CaC(6) and graphite. The ammonia absorption is irreversible in nature, and degassing the sample at elevated temperature leads to the formation of calcium amide and hydrogen. The Raman spectroscopy and magnetization studies show that the ammonia absorption not only leads to a large stacking disorder, but it also reduces the superconducting CaC(6) phase fraction. Finally, we propose a molecular stacking model which accounts for the observed ammonia absorption and concomitant structural phase transitions.

  8. Absorption of Solar Radiation by the Cloudy Atmosphere Interpretations of Collocated Aircraft Measurements

    Science.gov (United States)

    Valero, Francisco P. J.; Cess, Robert D.; Zhang, Minghua; Pope, Shelly K.; Bucholtz, Anthony; Bush, Brett; Vitko, John, Jr.

    1997-01-01

    As part of the Atmospheric Radiation Measurement (ARM) Enhanced Shortwave Experiment (ARESE), we have obtained and analyzed measurements made from collocated aircraft of the absorption of solar radiation within the atmospheric column between the two aircraft. The measurements were taken during October 1995 at the ARM site in Oklahoma. Relative to a theoretical radiative transfer model, we find no evidence for excess solar absorption in the clear atmosphere and significant evidence for its existence in the cloudy atmosphere. This excess cloud solar absorption appears to occur in both visible (0.224-0.68 microns) and near-infrared (0.68-3.30 microns) spectral regions, although not at 0.5 microns for the visible contribution, and it is shown to be true absorption rather than an artifact of sampling errors caused by measuring three-dimensional clouds.

  9. Quasi zero-background tunable diode laser absorption spectroscopy employing a balanced Michelson interferometer.

    Science.gov (United States)

    Guan, Zuguang; Lewander, Märta; Svanberg, Sune

    2008-12-22

    Tunable diode laser spectroscopy (TDLS) normally observes small fractional absorptive reductions in the light flux. We show, that instead a signal increase on a zero background can be obtained. A Michelson interferometer, which is initially balanced out in destructive interference, is perturbed by gas absorption in one of its arms. Both theoretical analysis and experimental demonstration show that the proposed zero-background TDLS can improve the achievable signal-to-noise ratio.

  10. Absorption of copper(II) by creosote bush (Larrea tridentata): use of atomic and x-ray absorption spectroscopy.

    Science.gov (United States)

    Gardea-Torresdey, J L; Arteaga, S; Tiemann, K J; Chianelli, R; Pingitore, N; Mackay, W

    2001-11-01

    Larrea tridentata (creosote bush), a common North American native desert shrub, exhibits the ability to take up copper(II) ions rapidly from solution. Following hydroponic studies, U.S. Environmental Protection Agency method 200.3 was used to digest the plant samples, and flame atomic absorption spectroscopy (FAAS) was used to determine the amount of copper taken up in different parts of the plant. The amount of copper(II) found within the roots, stems, and leaves was 13.8, 1.1, and 0.6 mg/g, respectively, after the creosote bush was exposed to a 63.5-ppm copper(II) solution for 48 h. When the plant was exposed to a 635-ppm copper(II) solution, the roots, stems, and leaves contained 35.0, 10.5, and 3.8 mg/g, respectively. In addition to FAAS analysis, x-ray microfluorescence (XRMF) analysis of the plant samples provided further confirmation of copper absorption by the various plant parts. X-ray absorption spectroscopy (XAS) elucidated the oxidation state of the copper absorbed by the plants. The copper(II) absorbed from solution remained as copper(II) bound to oxygen-containing ligands within the plant samples. The results of this study indicate that creosote bush may provide a useful and novel method of removing copper(II) from contaminated soils in an environmentally friendly manner.

  11. Microwave dielectric absorption spectroscopy aiming at novel dosimetry using DNAs

    Energy Technology Data Exchange (ETDEWEB)

    Izumi, Yoshinobu; Hirayama, Makoto; Matuo, Youichirou [Research Institute of Nuclear Engineering, University of Fukui, Fukui (Japan); Sunagawa, Takeyoshi [Fukui University of Technology, Fukui (Japan)

    2017-03-15

    We are developing L-band and S-band microwave dielectric absorption systems aiming novel dosimetry using DNAs, such as plasmid DNA and genomic DNA, and microwave technology. Each system is composed of a cavity resonator, analog signal generator, circulator, power meter, and oscilloscope. Since the cavity resonator is sensitive to temperature change, we have made great efforts to prevent the fluctuation of temperature. We have developed software for controlling and measurement. By using this system, we can measure the resonance frequency, f, and ΔQ (Q is a dimensionless parameter that describes how under-damped an oscillator or resonator is, and characterizes a resonator’s bandwidth relative to its center frequency) within about 3 minutes with high accuracy. This system will be expected to be applicable to DNAs evaluations and to novel dosimetric system.

  12. Performance modelling and simulation of an absorption solar cooling system for Malaysia

    International Nuclear Information System (INIS)

    Assilzadeh, F.; Ali, Y.; Kamaruzzaman Sopian

    2006-01-01

    Solar radiation contains huge amounts of energy and is required for almost all the natural processes on earth. Solar-powered air-conditioning has many advantages when compared to normal electricity system. This paper presents a solar cooling system that has been designed for Malaysia and other tropical regions using evacuated tube solar collector and LiBr absorption system. A modelling and simulation of absorption solar cooling system is modeled in Transient System Simulation (TRNSYS) environment. The typical meteorological year file containing the weather parameters is used to simulate the system. Then a system optimization is carried out in order to select the appropriate type of collector, the optimum size of storage tank, the optimum collector slope and area and the optimum thermostat setting of the auxiliary boiler

  13. Enhanced solar light absorption of graphene by interaction with anisole

    KAUST Repository

    Kahaly, M. Upadhyay

    2014-10-01

    We study suspended graphene in contact with the organic molecule anisole to analyse the implications of the interaction for the optical absorption, using first principle calculations. Because of a weak interaction multiple orientations of the molecule with respect to the graphene sheet are possible. A substantial enhancement of the optical absorption independent of the specific orientation is observed, which is promising for energy harvesting. © 2014 Elsevier Ltd. All rights reserved.

  14. A structural study of ceramic oxides by X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Akhtar, M.J.

    1995-01-01

    A detailed structural study of ceramic oxides is presented by employing X-ray Absorption Spectroscopy (XAS). In the present work X-ray Absorption Near Edge Structure (XANES) is used for the investigation of valence state of metal cations; whereas, Extended X-ray Absorption Fine Structure EXAFS) is employed for the determination for bond lengths, coordination numbers and nature of the elements present in the near neighbour shells surrounding the absorbing atom. These results show that local environment of dopant and host cations are different; and this variation in local structure depends on the nature and concentration of the dopant ions. (author)

  15. Thyroid lesions diagnosis by Fourier transformed infrared absorption spectroscopy (FTIR)

    International Nuclear Information System (INIS)

    Albero, Felipe Guimaraes

    2009-01-01

    Thyroid nodules are a common disorder, with 4-7% of incidence in the Brazilian population. Although the fine needle aspiration (FNA) is an accurate method for thyroid tumors diagnosis, the discrimination between benign and malignant neoplasm is currently not possible in some cases with high incidence of false negative diagnosis, leading to a surgical intervention due to the risk of carcinomas. The aim of this study was to verify if the Fourier Transform infrared spectroscopy (FTIR) can contribute to the diagnosis of thyroid carcinomas and goiters, using samples of tissue and aspirates. Samples of FNA, homogenates and tissues of thyroid nodules with histopathological diagnosis were obtained and prepared for FTIR spectroscopy analysis. The FNA and homogenates samples were measured by μ-FTIR (between 950 . 1750 cm -1 ), at a nominal resolution of 4 cm -1 and 120 scans). Tissue samples were analyzed directly by ATR-FTIR technique, at a resolution 2 cm -1 , with 60 scans in the same region. All spectra were corrected by the baseline and normalized by amides area (1550-1640 cm -1 ) in order to minimize variations of sample homogeneity. Then, spectra were converted into second derivatives using the Savitzk-Golay algorithm with a 13 points window. The Ward's minimum variance algorithm and Euclidean distances among the points were used for cluster analysis. Some FNA samples showed complex spectral pattern. All samples showed some cell pellets and large amount of hormone, represented by the bands of 1545 and 1655 cm -1 . Bands in 1409, 1412, 1414, 1578 and 1579 cm -1 were also found, indicating possible presence of sugar, DNA, citric acid or metabolic products. In this study, it was obtained an excellent separation between goiter and malign lesion for the samples of tissues, with 100% of specificity in specific cluster and 67% sensibility and 50 of specificity. In homogenate and FNA samples this sensibility and specificity were lower, because among these samples, it were

  16. Energy and parametric analysis of solar absorption cooling systems in various Moroccan climates

    Directory of Open Access Journals (Sweden)

    Y. Agrouaz

    2017-03-01

    Full Text Available The aim of this work is to investigate the energetic performance of a solar cooling system using absorption technology under Moroccan climate. The solar fraction and the coefficient of performance of the solar cooling system were evaluated for various climatic conditions. It is found that the system operating in Errachidia shows the best average annual solar fraction (of 30% and COP (of 0.33 owing to the high solar capabilities of this region. Solar fraction values in other regions varied between 19% and 23%. Moreover, the coefficient of performance values shows in the same regions a significant variation from 0.12 to 0.33 all over the year. A detailed parametric study was as well carried out to evidence the effect of the operating and design parameters on the solar air conditioner performance.

  17. Absorption generator for solar-powered air-conditioner

    Science.gov (United States)

    Lowen, D. J.; Murray, J. G.

    1977-01-01

    Device passes solar-heated water through coils. Hot lithium Bromide/Water solution leaves through central stand-pipe, and water vapor leaves through refrigerant outlet at top. Matching generation temperature to collector efficiency helps cut costs.

  18. Hyperfine structure of 147,149Sm measured using saturated absorption spectroscopy in combination with resonance-ionization mass spectroscopy

    International Nuclear Information System (INIS)

    Park, Hyunmin; Lee, Miran; Rhee, Yongjoo

    2003-01-01

    The hyperfine structures of four levels of the Sm isotopes have been measured by means of diode-laser-based Doppler-free saturated absorption spectroscopy in combination with a diode-laser-initiated resonance-ionization mass spectroscopy. It was demonstrated that combining the two spectroscopic methods was very effective for the identification and accurate measurement of the spectral lines of atoms with several isotopes, such as the rare-earth elements. From the obtained spectra, the hyperfine constants A and B for the odd-mass isotopes 147 Sm and 149 Sm were determined for four upper levels of the studied transitions.

  19. Ionospheric Absorption on 1539 Khz in Relation to Solar Ionizing Radiation

    Science.gov (United States)

    Boska, J.

    1984-01-01

    Radio wave absorption data on 1539 kHz for the summer period of 1978 to 1980 are considered in relation to variations of solar X-ray and L-alpha radiation. It is shown that under non-flare conditions L-alpha dominates in controlling absorption and that X-rays contribute about 10% to the total absorption. Optimum regression equations show that absorption is proportional to the m-th power of ionizing flux where m 1. The role of correcting L-alpha values, measured by the AE-E satellite, is discussed.

  20. Design of Molecular Solar Cells via Feedback from Soft X-ray Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Himpsel, Franz J. [Univ. of Wisconsin, Madison, WI (United States)

    2015-06-12

    Spectroscopy with soft X-rays was used to develop new materials and novel designs for solar cells and artificial photosynthesis. In order to go beyond the widely-used trial-and-error approach of gradually improving a particular design, we started from the most general layout of a solar cell (or a photo-electrochemical device) and asked which classes of materials are promising for best performance. For example, the most general design of a solar cell consists of a light absorber, an electron donor, and an electron acceptor. These are characterized by four energy levels, which were measured by a combination of spectroscopic X-ray techniques. Tuning synchrotron radiation to the absorption edges of specific elements provided element- and bond-selectivity. The spectroscopic results were complemented by state-of-the-art calculations of the electronic states. These helped explaining the observed energy levels and the orbitals associated with them. The calculations were extended to a large class of materials (for example thousands of porphyrin dye complexes) in order to survey trends in the energy level structure. A few highlights serve as examples: 1) Organic molecules combining absorber, donor, and acceptor with atomic precision. 2) Exploration of highly p-doped diamond films as inert, transparent electron donors. 3) Surface-sensitive characterization of nanorod arrays used as photoanodes in water splitting. 4) Computational design of molecular complexes for efficient solar cells using two photons.

  1. Quartz crystal microbalance and infrared reflection absorption spectroscopy characterization of bisphenol A absorption in the poly(acrylate) thin films.

    Science.gov (United States)

    Li, Guifeng; Morita, Shigeaki; Ye, Shen; Tanaka, Masaru; Osawa, Masatoshi

    2004-02-01

    The absorption process of bisphenol A (BPA) in a number of poly(acrylate) thin films, such as poly(2-methoxyethyl acrylate) (PMEA), poly(ethyl acrylate) (PEA), poly(n-butyl methacrylate) (PBMA), and poly(methyl methacrylate) (PMMA), has been investigated by quartz crystal microbalance (QCM) and infrared reflection absorption spectroscopy (IRRAS) measurements. Both QCM and IRRAS measurements show that the BPA molecules absorb in PMEA, PEA, and PBMA thin films but not in PMMA thin film. The differences in the BPA absorption behavior are mainly attributed to the difference in the glass transition temperature (T(g)) between these polymers. This absorption behavior also depends on the BPA concentration and polymer film thickness. Furthermore, IRRAS characterization demonstrates that the hydrogen bonding is formed between the hydroxyl group in BPA and the carbonyl group in the poly(acrylate) thin films. BPA molecule absorbed in these polymer thin films can be removed by ethanol rinse treatment. By optimizing experimental conditions for the QCM electrode modified by PMEA thin film, detection limitation of approximately 1 ppb for BPA can be realized by the in situ QCM measurement. This method is expected to be a sensitive in situ detection way for trace BPA in the environmental study.

  2. Plasmonic Nanostructure for Enhanced Light Absorption in Ultrathin Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    Jinna He

    2012-01-01

    Full Text Available The performances of thin film solar cells are considerably limited by the low light absorption. Plasmonic nanostructures have been introduced in the thin film solar cells as a possible solution around this issue in recent years. Here, we propose a solar cell design, in which an ultrathin Si film covered by a periodic array of Ag strips is placed on a metallic nanograting substrate. The simulation results demonstrate that the designed structure gives rise to 170% light absorption enhancement over the full solar spectrum with respect to the bared Si thin film. The excited multiple resonant modes, including optical waveguide modes within the Si layer, localized surface plasmon resonance (LSPR of Ag stripes, and surface plasmon polaritons (SPP arising from the bottom grating, and the coupling effect between LSPR and SPP modes through an optimization of the array periods are considered to contribute to the significant absorption enhancement. This plasmonic solar cell design paves a promising way to increase light absorption for thin film solar cell applications.

  3. Visible and infrared absorption spectra of covering materials for solar collectors

    International Nuclear Information System (INIS)

    Pelece, I.

    2008-01-01

    Use of solar energy increases every year. In Latvia, solar energy is used mainly by solar collectors. The main part of the solar collector is the absorber, but not less important is the covering material which protects the absorber from the cooling impact of the wind. This cover must be transparent for solar radiation, but opaque for thermal radiation of the absorber, which is at greater wavelengths. Therefore it is important to measure absorption spectra of possible covering materials at visible and infrared wavelength ranges. Absorption spectra have been measured for several materials: glass, polythene, Plexiglas, and cells Plexiglas. Absorption spectra for all these materials are measured in three ranges: ultraviolet-visible (UV-VIS): 250-1000 nm; near infrared (NIR): 700-110 nm; infrared (IR): 1200-8000 nm. UV-VIS spectra with the 'Ocean Optics' device HR-4000 have been measured, but NIR and IR - with 'Bruker' Furje spectrometer EQUINOX 55. Evaluation of absorption spectra showed that the most suitable material (from the considered) for covering of solar collectors is Plexiglas

  4. The influence of magnetic fields on absorption and emission spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Heshou; Yan, Huirong [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Potsdam Univ. (Germany). Inst. fuer Physik und Astronomie; Richter, Philipp [Potsdam Univ. (Germany). Inst. fuer Physik und Astronomie; Leibniz-Institut fuer Astrophysik Potsdam (AIP) (Germany)

    2016-10-15

    Spectroscopic observations play essential roles in astrophysics. They are crucial for determining important physical parameters, providing information about the composition of various objects in the universe, as well as depicting motions in the universe. However, spectroscopic studies often do not consider the influence of magnetic fields. In this paper, we explore the influence of magnetic fields on the spectroscopic observations arising from Ground State Alignment (GSA). Synthetic spectra are generated to show the measurable changes of the spectra due to GSA. The influences of atomic alignment on absorption from DLAs, emission from H II Regions, submillimeter fine-structure lines from star forming regions are presented as examples to illustrate the effect in diffuse gas. Furthermore, we demonstrate the influence of atomic alignment on physical parameters derived from spectral line ratios, such as the alpha-to-iron ratio([X/Fe]), interstellar temperature, and ionization rate. Results in our paper show that due to GSA, magnetic fields will affect the spectra of diffuse gas with high signal-to-noise(S/N) ratio under the condition that photon-excitation is much more efficient than thermal collision.

  5. Probing heme protein-ligand interactions by UV/visible absorption spectroscopy.

    Science.gov (United States)

    Nienhaus, Karin; Nienhaus, G Ulrich

    2005-01-01

    Ultraviolet/visible (UV/vis) absorption spectroscopy is a powerful tool for steady-state and time-resolved studies of protein-ligand interactions. Prosthetic groups in proteins frequently have strong electronic absorbance bands that depend on the oxidation, ligation, and conformation states of the chromophores. They are also sensitive to conformational changes of the polypeptide chain into which they are embedded. Steady-state absorption spectroscopy provides information on ligand binding equilibria, from which the Gibbs free energy differences between the ligated and unligated states can be computed. Time-resolved absorption spectroscopy allows one to detect short-lived intermediate states that may not get populated significantly under equilibrium conditions, but may nevertheless be of crucial importance for biological function. Moreover, the energy barriers that have to be surmounted in the reaction can be determined. In this chapter, we present a number of typical applications of steady-state and ns time-resolved UV/vis absorption spectroscopy in the study of ligand binding to the central iron in heme proteins.

  6. Spectral line shapes in linear absorption and two-dimensional spectroscopy with skewed frequency distributions

    NARCIS (Netherlands)

    Farag, Marwa H.; Hoenders, Bernhard J.; Knoester, Jasper; Jansen, Thomas L. C.

    2017-01-01

    The effect of Gaussian dynamics on the line shapes in linear absorption and two-dimensional correlation spectroscopy is well understood as the second-order cumulant expansion provides exact spectra. Gaussian solvent dynamics can be well analyzed using slope line analysis of two-dimensional

  7. Circuit Board Analysis for Lead by Atomic Absorption Spectroscopy in a Course for Nonscience Majors

    Science.gov (United States)

    Weidenhammer, Jeffrey D.

    2007-01-01

    A circuit board analysis of the atomic absorption spectroscopy, which is used to measure lead content in a course for nonscience majors, is being presented. The experiment can also be used to explain the potential environmental hazards of unsafe disposal of various used electronic equipments.

  8. Aggregation of Methylene Blue in Frozen Aqueous Solutions Studied by Absorption Spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Heger, D.; Jirkovský, Jaromír; Klán, J.

    2005-01-01

    Roč. 109, č. 30 (2005), s. 6702-6709 ISSN 1089-5639 Grant - others:GA ČR GA205/05/0819 Institutional research plan: CEZ:AV0Z40400503 Keywords : frozen aqueous solutions * methylene blue * absorption spectroscopy Subject RIV: CG - Electrochemistry Impact factor: 2.898, year: 2005

  9. X-ray absorption spectroscopy of CuO.sub.2./sub. chains

    Czech Academy of Sciences Publication Activity Database

    Drechsler, S.L.; Hu, Z.; Málek, Jiří; Rosner, H.; Neudert, R.; Knupfer, M.; Golden, M. S.; Fink, J.

    2003-01-01

    Roč. 131, 3/4 (2003), s. 369-373 ISSN 0022-2291 Institutional research plan: CEZ:AV0Z1010914 Keywords : X-ray absorption spectroscopy * exact diagonalization techniques Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.171, year: 2003

  10. Electro-Optical Multichannel Spectrometer for Transient Resonance Raman and Absorption Spectroscopy

    DEFF Research Database (Denmark)

    Hansen, Karina Benthin; Wilbrandt, Robert Walter; Pagsberg, Palle Bjørn

    1979-01-01

    An optical multichannel system is described, used for time‐dependent absorption measurements in the gas phase and the liquid phase and for resonance Raman spectroscopy of short‐lived transient species in the liquid phase in pulse radiolysis. It consists of either an image converter streak unit or...

  11. DETERMINING BERYLLIUM IN DRINKING WATER BY GRAPHITE FURNACE ATOMIC ABSORPTION SPECTROSCOPY

    Science.gov (United States)

    A direct graphite furnace atomic absorption spectroscopy method for the analysis of beryllium in drinking water has been derived from a method for determining beryllium in urine. Ammonium phosphomolybdate and ascorbic acid were employed as matrix modifiers. The matrix modifiers s...

  12. The photochemical ring opening reaction of chromene as seen by transient absorption and fluorescence spectroscopy

    NARCIS (Netherlands)

    Herzog, Teja T.; Ryseck, Gerald; Ploetz, Evelyn; Cordes, Thorben

    2013-01-01

    In this paper we investigate the photochromic ring-opening reaction of 2,2-diphenyl-5,6-benzo(2H)-chromene. In particular, we study the uncertainties and contradictions in various published reaction models using a combination of transient absorption and fluorescence spectroscopy with femtosecond

  13. Measurement of Absorption Coefficient of Paraformaldehyde and Metaldehyde with Terahertz Spectroscopy

    Science.gov (United States)

    Zhang, J.; Xia, T.; Chen, Q.; Sun, Q.; Deng, Y.; Wang, C.

    2018-03-01

    The characteristic absorption spectra of paraformaldehyde and metaldehyde in the terahertz frequency region are obtained by terahertz time-domain spectroscopy (THz-TDS). In order to reduce the absorption of terahertz (THz) wave by water vapor in the air and the background noise, the measurement system was filled with dry air and the measurements were conducted at the temperature of 24°C. Meanwhile, the humidity was controlled within 10% RH. The THz frequency domain spectra of samples and their references from 0 to 2.5 THz were analyzed via Fourier transform. The refractive index and absorption coefficients of the two aldehydes were calculated by the model formulas. From 0.1 to 2.5 THz, there appear two weak absorption peaks at 1.20 and 1.66 THz in the absorption spectra of paraformaldehyde. Only one distinct absorption peak emerges at 1.83 THz for metaldehyde. There are significant differences between the terahertz absorption coefficients of paraformaldehyde and metaldehyde, which can be used as "fingerprints" to identify these substances. Furthermore, the relationship between the average absorption coefficients and mass concentrations was investigated and the average absorption coefficient-mass concentration diagrams of paraformaldehyde and metaldehyde were shown. For paraformaldehyde, there is a linear relationship between the average absorption coefficient and the natural logarithm of mass concentration. For metaldehyde, there exists a simpler linear relationship between the average absorption coefficient and the mass concentration. Because of the characteristics of THz absorption of paraformaldehyde and metaldehyde, the THz-TDS can be applied to the qualitative and quantitative detection of the two aldehydes to reduce the unpredictable hazards due to these substances.

  14. Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hellman, Hal

    1968-01-01

    This booklet discusses spectroscopy, the study of absorption of radiation by matter, including X-ray, gamma-ray, microwave, mass spectroscopy, as well as others. Spectroscopy has produced more fundamental information to the study of the detailed structure of matter than any other tools.

  15. DOAS (differential optical absorption spectroscopy) urban pollution measurements

    Science.gov (United States)

    Stevens, Robert K.; Vossler, T. L.

    1991-05-01

    During July and August of 1990, a differential optical absorption spectrometer (DOAS) made by OPSIS Inc. was used to measure gaseous air pollutants over three separate open paths in Atlanta, GA. Over path 1 (1099 m) and path 2 (1824 m), ozone (03), sulfur dioxide (SO2) nitrogen dioxide (NO2), nitrous acid (HNO2) formaldehyde (HCHO), benzene, toluene, and o-xylene were measured. Nitric oxide (NO) and ammonia (NH3) were monitored over path 3 (143 m). The data quality and data capture depended on the compound being measured and the path over which it was measured. Data quality criteria for each compound were chosen such that the average relative standard deviation would be less than 25%. Data capture ranged from 43% for o-xylene for path 1 to 95% for ozone for path 2. Benzene, toluene, and o-xylene concentrations measured over path 2, which crossed over an interstate highway, were higher than concentrations measured over path 1, implicating emissions from vehicles on the highway as a significant source of these compounds. Federal Reference Method (FRN) instruments were located near the DOAS light receivers and measurements of 03, NO2, and NO were made concurrently with the DOAS. Correlation coefficients greater than 0.85 were obtained between the DOAS and FRM's; however, there was a difference between the mean values obtained by the two methods for 03 and NO. A gas chromatograph for measuring volatile organic compounds was operated next to the FRN's. Correlation coefficients of about 0.66 were obtained between the DOAS and GC measurements of benzene and o- xylene. However, the correlation coefficient between the DOAS and GC measurements of toluene averaged only 0.15 for the two DOAS measurement paths. The lack of correlation and other factors indicate the possibility of a localized source of toluene near the GC. In general, disagreements between the two measurement methods could be caused by atmospheric inhomogeneities or interferences in the DOAS and other methods.

  16. Effects of Ag Nanocubes with Different Corner Shape on the Absorption Enhancement in Organic Solar Cells

    Directory of Open Access Journals (Sweden)

    Feng Shan

    2014-01-01

    Full Text Available The effects of corner shape of silver (Ag nanocubes (NCs on optical absorptions of organic solar cells (OSCs are theoretically investigated by finite element method (FEM calculations. The absorption of sun light in the active layer is calculated. Significant absorption enhancements have been demonstrated in metallic region with different shapes of Ag NCs, among them corner radius (R is zero result in the best light absorption performance of up to 55% enhancement with respect to bare OSCs. The origins of increased absorption are believed to be the effects of the huge electric field enhancement and increased scattering upon the excitation of localized surface plasmon resonance (LSPR. Apart from using R=0, we show that R=3, 6, and 11.29 of Ag NCs in metallic region of active layer may also result in the maximum comparable absorption enhancement of 49%, 41%, and 28%, respectively. In addition, a significant effect of the period of NCs is observed.

  17. Differential optical absorption spectroscopy (DOAS and air mass factor concept for a multiply scattering vertically inhomogeneous medium: theoretical consideration

    Directory of Open Access Journals (Sweden)

    V. V. Rozanov

    2010-06-01

    Full Text Available The Differential Optical Absorption Spectroscopy (DOAS technique is widely used to retrieve amounts of atmospheric species from measurements of the direct solar light transmitted through the Earth's atmosphere as well as of the solar light scattered in the atmosphere or reflected from the Earth's surface. For the transmitted direct solar light the theoretical basis of the DOAS technique represented by the Beer-Lambert law is well studied. In contrast, scarcely investigated is the theoretical basis and validity range of the DOAS method for those cases where the contribution of the multiple scattering processes is not negligible. Our study is intended to fill this gap by means of a theoretical investigation of the applicability of the DOAS technique for the retrieval of amounts of atmospheric species from observations of the scattered solar light with a non-negligible contribution of the multiple scattering.

    Starting from the expansion of the intensity logarithm in the functional Taylor series we formulate the general form of the DOAS equation. The thereby introduced variational derivative of the intensity logarithm with respect to the variation of the gaseous absorption coefficient, which is often referred to as the weighting function, is demonstrated to be closely related to the air mass factor. Employing some approximations we show that the general DOAS equation can be rewritten in the form of the weighting function (WFDOAS, the modified (MDOAS, and the standard DOAS equations. For each of these forms a specific equation for the air mass factor follows which, in general, is not suitable for other forms of the DOAS equation. Furthermore, the validity range of the standard DOAS equation is quantitatively investigated using a suggested criterion of a weak absorption.

    The results presented in this study are intended to provide a basis for a better understanding of the applicability range of different forms of the DOAS equation as

  18. SELF-ABSORPTION IN THE SOLAR TRANSITION REGION

    International Nuclear Information System (INIS)

    Yan, Limei; He, Jiansen; Wang, Linghua; Tu, Chuanyi; Zhang, Lei; Peter, Hardi; Chen, Feng; Barczynski, Krzysztof; Tian, Hui; Xia, Lidong

    2015-01-01

    Transient brightenings in the transition region of the Sun have been studied for decades and are usually related to magnetic reconnection. Recently, absorption features due to chromospheric lines have been identified in transition region emission lines raising the question of the thermal stratification during such reconnection events. We analyze data from the Interface Region Imaging Spectrograph in an emerging active region. Here the spectral profiles show clear self-absorption features in the transition region lines of Si iv. While some indications existed that opacity effects might play some role in strong transition region lines, self-absorption has not been observed before. We show why previous instruments could not observe such self-absorption features, and discuss some implications of this observation for the corresponding structure of reconnection events in the atmosphere. Based on this we speculate that a range of phenomena, such as explosive events, blinkers or Ellerman bombs, are just different aspects of the same reconnection event occurring at different heights in the atmosphere

  19. Determination of Calcium in Cereal with Flame Atomic Absorption Spectroscopy: An Experiment for a Quantitative Methods of Analysis Course

    Science.gov (United States)

    Bazzi, Ali; Kreuz, Bette; Fischer, Jeffrey

    2004-01-01

    An experiment for determination of calcium in cereal using two-increment standard addition method in conjunction with flame atomic absorption spectroscopy (FAAS) is demonstrated. The experiment is intended to introduce students to the principles of atomic absorption spectroscopy giving them hands on experience using quantitative methods of…

  20. Charge Carrier Dynamics of Quantum Confined Semiconductor Nanoparticles Analyzed via Transient Absorption Spectroscopy

    Science.gov (United States)

    Thibert, Arthur Joseph, III

    were passivated for water solubility via two different methods: hydrosilylation produced 3-aminopropenyl-terminated Si quantum dots, and a modified Stöber process produced silica-encapsulated Si quantum dots. Both methods produce water-soluble quantum dots with maximum emission at 414 nm, and after purification, the quantum dots exhibit intrinsic fluorescence quantum yield efficiencies of 15 and 23%, respectively. Even though the quantum dots have different surfaces, they exhibit nearly identical absorption and fluorescence spectra. Femtosecond transient absorption spectroscopy was used for temporal resolution of the photoexcited carrier dynamics between the quantum dots and ligand. The transient dynamics of the 3-aminopropenyl-terminated Si quantum dots is interpreted as a formation and decay of a charge-transfer excited state between the delocalized π electrons of the carbon linker and the Si core excitons. This charge transfer state is stable for ~4 ns before reverting back to a more stable, long-living species. The silica-encapsulated Si QDs show a simpler spectrum without charge transfer dynamics. Appendix I (Chem. Mat., 1220, 2010), addresses the long-time (μs) transient kinetics associated with TiO2 and layered titanates (TBA2 2Ti4O9), which were synthesized in the Osterloh laboratory (UCD). Transient absorption data reveal that photogenerated electrons become trapped in mid band-gap states, from which they decay exponentially with a time-constant of 43.67 + 0.28 ms in titanates, which is much slower than the 68 + 1 ns observed for TiO2 nanocrystals. The slower kinetics observed for the TBA 2Ti4O9 nanosheets originates either from the presence of deeper trap sites on the sheets vs. the nanoparticles, more trap sites, or from more effective electron-hole separation because of the micrometer dimensions of the 2D lattice. Appendix II, depicts the visible solar spectrum at sea level detailing the percentage of photons and energy that exist within certain

  1. Boundary Layer of Photon Absorption Applied to Heterogeneous Photocatalytic Solar Flat Plate Reactor Design

    Directory of Open Access Journals (Sweden)

    Héctor L. Otálvaro-Marín

    2014-01-01

    Full Text Available This study provides information to design heterogeneous photocatalytic solar reactors with flat plate geometry used in treatment of effluents and conversion of biomass to hydrogen. The concept of boundary layer of photon absorption taking into account the efficient absorption of radiant energy was introduced; this concept can be understood as the reactor thickness measured from the irradiated surface where 99% of total energy is absorbed. Its thickness and the volumetric rate of photons absorption (VRPA were used as design parameters to determine (i reactor thickness, (ii maximum absorbed radiant energy, and (iii the optimal catalyst concentration. Six different commercial brands of titanium dioxide were studied: Evonik-Degussa P-25, Aldrich, Merck, Hombikat, Fluka, and Fisher. The local volumetric rate of photon absorption (LVRPA inside the reactor was described using six-flux absorption-scattering model (SFM applied to solar radiation. The radiation field and the boundary layer thickness of photon absorption were simulated with absorption and dispersion effects of catalysts in water at different catalyst loadings. The relationship between catalyst loading and reactor thickness that maximizes the absorption of radiant energy was obtained for each catalyst by apparent optical thickness. The optimum concentration of photocatalyst Degussa P-25 was 0.2 g/l in 0.86 cm of thickness, and for photocatalyst Aldrich it was 0.3 g/l in 0.80 cm of thickness.

  2. Thermal Analysis of a Solar Powered Absorption Cooling System with Fully Mixed Thermal Storage at Startup

    Directory of Open Access Journals (Sweden)

    Camelia Stanciu

    2017-01-01

    Full Text Available A simple effect one stage ammonia-water absorption cooling system fueled by solar energy is analyzed. The considered system is composed by a parabolic trough collector concentrating solar energy into a tubular receiver for heating water. This is stored in a fully mixed thermal storage tank and used in the vapor generator of the absorption cooling system. Time dependent cooling load is considered for the air conditioning of a residential two-storey house. A parametric study is performed to analyze the operation stability of the cooling system with respect to solar collector and storage tank dimensions. The results emphasized that there is a specific storage tank dimension associated to a specific solar collector dimension that could ensure the longest continuous startup operation of the cooling system when constant mass flow rates inside the system are assumed.

  3. Warming trends in Asia amplified by brown cloud solar absorption.

    Science.gov (United States)

    Ramanathan, Veerabhadran; Ramana, Muvva V; Roberts, Gregory; Kim, Dohyeong; Corrigan, Craig; Chung, Chul; Winker, David

    2007-08-02

    Atmospheric brown clouds are mostly the result of biomass burning and fossil fuel consumption. They consist of a mixture of light-absorbing and light-scattering aerosols and therefore contribute to atmospheric solar heating and surface cooling. The sum of the two climate forcing terms-the net aerosol forcing effect-is thought to be negative and may have masked as much as half of the global warming attributed to the recent rapid rise in greenhouse gases. There is, however, at least a fourfold uncertainty in the aerosol forcing effect. Atmospheric solar heating is a significant source of the uncertainty, because current estimates are largely derived from model studies. Here we use three lightweight unmanned aerial vehicles that were vertically stacked between 0.5 and 3 km over the polluted Indian Ocean. These unmanned aerial vehicles deployed miniaturized instruments measuring aerosol concentrations, soot amount and solar fluxes. During 18 flight missions the three unmanned aerial vehicles were flown with a horizontal separation of tens of metres or less and a temporal separation of less than ten seconds, which made it possible to measure the atmospheric solar heating rates directly. We found that atmospheric brown clouds enhanced lower atmospheric solar heating by about 50 per cent. Our general circulation model simulations, which take into account the recently observed widespread occurrence of vertically extended atmospheric brown clouds over the Indian Ocean and Asia, suggest that atmospheric brown clouds contribute as much as the recent increase in anthropogenic greenhouse gases to regional lower atmospheric warming trends. We propose that the combined warming trend of 0.25 K per decade may be sufficient to account for the observed retreat of the Himalayan glaciers.

  4. Solar irradiance in the stratosphere - Implications for the Herzberg continuum absorption of O2

    Science.gov (United States)

    Frederick, J. E.; Mentall, J. E.

    1982-01-01

    A set of solar irradiance observations is analyzed that were performed from the third Solar Absorption Balloon Experiment (SABE-3) as the payload ascended through the stratosphere from 32 to 39 km. Comparison of these data with calculations of the attenuated irradiance based on simultaneous ozone and pressure measurements made from the payload suggests a refinement of the cross section values used in photochemical models. More ultraviolet radiation in the 200-210 nm spectral region reaches the middle stratosphere than is predicted by the absorption data presently available. It is suggested that significantly smaller values for the Herzberg continuum of O2 be used in future models.

  5. Relative spectral absorption of solar radiation by water vapor and cloud droplets

    Science.gov (United States)

    Davies, R.; Ridgway, W. L.

    1983-01-01

    A moderate (20/cm) spectral resolution model which accounts for both the highly variable spectral transmission of solar radiation through water vapor within and above cloud, as well as the more slowly varying features of absorption and anisotropic multiple scattering by the cloud droplets, is presented. Results from this model as applied to the case of a typical 1 km thick stratus cloud in a standard atmosphere, with cloud top altitude of 2 km and overhead sun, are discussed, showing the relative importance of water vapor above the cloud, water vapor within the cloud, and cloud droplets on the spectral absorption of solar radiation.

  6. Diaryl-substituted norbornadienes with red-shifted absorption for molecular solar thermal energy storage.

    Science.gov (United States)

    Gray, Victor; Lennartson, Anders; Ratanalert, Phasin; Börjesson, Karl; Moth-Poulsen, Kasper

    2014-05-25

    Red-shifting the absorption of norbornadienes (NBDs), into the visible region, enables the photo-isomerization of NBDs to quadricyclanes (QCs) to be driven by sunlight. This is necessary in order to utilize the NBD-QC system for molecular solar thermal (MOST) energy storage. Reported here is a study on five diaryl-substituted norbornadienes. The introduced aryl-groups induce a significant red-shift of the UV/vis absorption spectrum of the norbornadienes, and device experiments using a solar-simulator set-up demonstrate the potential use of these compounds for MOST energy storage.

  7. Intracavity absorption spectroscopy of formaldehyde from 6230 to 6420 cm-1

    Science.gov (United States)

    Fjodorow, Peter; Hellmig, Ortwin; Baev, Valery M.; Levinsky, Howard B.; Mokhov, Anatoli V.

    2017-05-01

    We apply intracavity absorption spectroscopy for measurements of the absorption spectrum of formaldehyde, CH2O, from 6230 to 6420 cm-1, of which only a small fraction (6351-6362 cm-1) has been recorded elsewhere. The measurements are performed in the cavity of a broadband Er3+-doped fiber laser, with a sensitivity corresponding to the effective absorption path length of 45 m and a spectral resolution of 0.1 cm-1. The noise-equivalent detection limit of CH2O achieved with the strongest absorption line at 6252.64 cm-1 is estimated to be 5 ppm. High tolerance to broadband losses and the accessible time resolution of 50 µs make it possible to apply this detection system for time-resolved monitoring of CH2O together with other molecules in harsh combustion environments, e.g., in combustion engines.

  8. Fourier-Transform Photocurrent Spectroscopy for a fast and highly sensitive spectral characterization of organic and hybrid solar cells

    International Nuclear Information System (INIS)

    Vandewal, K.; Goris, L.; Haeldermans, I.; Nesladek, M.; Haenen, K.; Wagner, P.; Manca, J.V.

    2008-01-01

    Two modes of Fourier-Transform Photocurrent Spectroscopy (FTPS) are presented for a fast and sensitive determination of photocurrent spectra of organic and dye sensitized solar cells. Furthermore, FTPS allows to spectrally resolve sub-bandgap absorption phenomena in P3HT, in organic P3HT:PCBM bulk heterojunctions and in hybrid P3HT/TiO 2 solar cells. The sub-bandgap absorption in the P3HT:PCBM blend is dominated by a band due to the formation of a ground-state charge-transfer complex between the polymer and PCBM. In P3HT/TiO 2 junctions such a charge-transfer complex band is not observed. Long-lived light induced sub-bandgap states appear in pure P3HT and in P3HT/TiO 2 junctions after irradiation with E > 1.9 eV

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

    Directory of Open Access Journals (Sweden)

    Alexander Klein

    2014-11-01

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

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

    Science.gov (United States)

    Klein, Alexander; Witzel, Oliver; Ebert, Volker

    2014-01-01

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

  11. Heating of solar coronal loops by resonant absorption of Alfven waves

    Science.gov (United States)

    Grossmann, William; Smith, Robert A.

    1988-01-01

    Numerical calculations governing the efficiency of coronal loop heating by the resonant absorption of shear Alfven waves are reported. The loop structure is modeled by a class of axisymmetric force-free equilibria of a long straight cylinder, approximating a large aspect ratio loop. For a range of parameters characterizing the evolution of solar coronal loops, the absorption bandwidth falls in the frequency range of the photospheric motions due to granulation and p-modes. Resonant Alfven wave absorption is thus a viable mechanism for coronal loop heating.

  12. SPATIAL DISTRIBUTIONS OF ABSORPTION, LOCAL SUPPRESSION, AND EMISSIVITY REDUCTION OF SOLAR ACOUSTIC WAVES IN MAGNETIC REGIONS

    International Nuclear Information System (INIS)

    Chou, D.-Y.; Yang, M.-H.; Zhao Hui; Liang Zhichao; Sun, M.-T.

    2009-01-01

    Observed acoustic power in magnetic regions is lower than the quiet Sun because of absorption, emissivity reduction, and local suppression of solar acoustic waves in magnetic regions. In the previous studies, we have developed a method to measure the coefficients of absorption, emissivity reduction, and local suppression of sunspots. In this study, we go one step further to measure the spatial distributions of three coefficients in two active regions, NOAA 9055 and 9057. The maps of absorption, emissivity reduction, and local suppression coefficients correlate with the magnetic map, including plage regions, except the emissivity reduction coefficient of NOAA 9055 where the emissivity reduction coefficient is too weak and lost among the noise.

  13. Real-time monitoring of atom vapor concentration with laser absorption spectroscopy

    International Nuclear Information System (INIS)

    Fan Fengying; Gao Peng; Jiang Tao

    2012-01-01

    The technology of laser absorption spectroscopy was used for real-time monitoring of gadolinium atom vapor concentration measurement and the solid state laser pumped ring dye laser was used as optical source. The optical fiber was taken to improve the stability of laser transmission. The multi-pass absorption technology combined with reference optical signal avoided the influence of laser power fluctuation. The experiment result shows that the system based on this detection method has a standard error of 4%. It is proved that the monitoring system provides reliable data for atom vapor laser isotope separation process and the separation efficiency can be improved. (authors)

  14. Performance Evaluation of a Nanofluid-Based Direct Absorption Solar Collector with Parabolic Trough Concentrator

    Directory of Open Access Journals (Sweden)

    Guoying Xu

    2015-12-01

    Full Text Available Application of solar collectors for hot water supply, space heating, and cooling plays a significant role in reducing building energy consumption. For conventional solar collectors, solar radiation is absorbed by spectral selective coating on the collectors’ tube/plate wall. The poor durability of the coating can lead to an increased manufacturing cost and unreliability for a solar collector operated at a higher temperature. Therefore, a novel nanofluid-based direct absorption solar collector (NDASC employing uncoated collector tubes has been proposed, and its operating characteristics for medium-temperature solar collection were theoretically and experimentally studied in this paper. CuO/oil nanofluid was prepared and used as working fluid of the NDASC. The heat-transfer mechanism of the NDASC with parabolic trough concentrator was theoretically evaluated and compared with a conventional indirect absorption solar collector (IASC. The theoretical analysis results suggested that the fluid’s temperature distribution in the NDASC was much more uniform than that in the IASC, and an enhanced collection efficiency could be achieved for the NDASC operated within a preferred working temperature range. To demonstrate the feasibility of the proposed NDASC, experimental performances of an NDASC and an IASC with the same parabolic trough concentrator were furthermore evaluated and comparatively discussed.

  15. Two-Photon Absorption Spectroscopy of Rubidium with a Dual-Comb Tequnique

    Science.gov (United States)

    Nishiyama, Akiko; Yoshida, Satoru; Hariki, Takuya; Nakajima, Yoshiaki; Minoshima, Kaoru

    2017-06-01

    Dual-comb spectroscopies have great potential for high-resolution molecular and atomic spectroscopies, thanks to the broadband comb spectrum consisting of dense narrow modes. In this study, we apply the dual-comb system to Doppler-free two-photon absorption spectroscopy. The outputs of two frequency combs excite several two-photon transitions of rubidium, and we obtained broadband Doppler-free spectra from dual-comb fluorescence signals. The fluorescence detection scheme circumvents the sensitivity limit which is effectively determined by the dynamic range of photodetectors in absorption-based dual-comb spectroscopies. Our system realized high-sensitive, Doppler-free high-resolution and broadband atomic spectroscopy. A part of observed spectra of 5S_{1/2} - 5D_{5/2} transition is shown in the figure. The hyperfine structures of the F" = 1 - F' = 3,2,1 transitions are fully-resolved and the spectral widths are approximately 5 MHz. The absolute frequency axis is precisely calibrated from comb mode frequencies which were stabilized to a GPS-disciplined clock. This work was supported by JST through the ERATO MINOSHIMA Intelligent Optical Synthesizer Project and Grant-in-Aid for JSPS Fellows (16J02345). A. Nishiyama, S. Yoshida, Y. Nakajima, H. Sasada, K. Nakagawa, A. Onae, K. and Minoshima, Opt. Express 24, 25894 (2016). A. Hipke, S. A. Meek, T. Ideguchi, T.W. Hänsch, and N. Picqué, Phys. Rev. A 90, 011805(R) (2014).

  16. Absorption enhancement in metal nanoparticles for photoemission current for solar cells

    DEFF Research Database (Denmark)

    Gritti, Claudia; Novitsky, Andrey; Malureanu, Radu

    2012-01-01

    In order to improve the photoconversion efficiency, we consider the possibility of increasing the photocurrent in solar cells exploiting the electron photoemission from small metal nanoparticles into a semiconductor. The effect is caused by the absorption of photons and generation of local surfac...

  17. Using Terahertz Spectroscopy to Study Systems with Solar Energy Applications

    Science.gov (United States)

    Milot, Rebecca L.; Moore, Gary F.; Martini, Lauren A.; Brudvig, Gary W.; Crabtree, Robert H.; Schmuttenmaer, Charles A.

    2013-06-01

    Biomimetic solar water oxidation systems are being developed as renewable alternatives to fossil fuels. One possible design incorporates thin-film dye-sensitized nanoparticle photoanades to capture and convert visible light to charge carriers and catalysts to facilitate water oxidation. The physical properties of the dye are important due to its position as the light absorber and electron transfer initiator. Given the role that porphyrins play in photosynthesis and their synthetic tunability, they are promising components for these photoanodes. Time-Resolved THz Spectroscopy (TRTS), an optical pump/THz probe technique, is a non-contact electrical probe with proven usefulness for studying electron transfer and conductivity on a sub-picosecond timescale. Using TRTS, the efficiency and dynamics of electron injection from porphyrin dyes into metal oxide surfaces was found to be strongly influenced by the structure and photophysical properties of the dye.

  18. Volumetric solar absorption in a channel with presence of phase change material in a carrier fluid

    International Nuclear Information System (INIS)

    Siddiqui, O.K.; Yilbas, Bekir S.; Shuja, S.Z.; Wang, E.

    2016-01-01

    Highlights: • Thermal energy gain over the solar heat input is high for absorber plate location at bottom surface of channel. • Phase change particles increases performance parameter as compared to water only case. • Pump power loss parameter behaves similar for absorbing plate location at top and at the bottom of channel. - Abstract: A channel flow with a presence of phase change particles in the carrier fluid (water) is investigated for various Reynolds numbers in relation to a solar volumetric absorption system. The absorber plate is considered in the channel to resemble the selective surface in the solar volumetric absorbing system. The absorbing plate, which composes of a ZrN film deposited onto a thin silver plate, is placed at three different locations in the channel to enhance the absorption of the incident solar radiation. The performance parameter is defined to quantify the heat storage capacity of the working fluid. The pump power loss parameter is introduced to predict the pump power loss due to the different locations of the absorber plate in the channel. A radiation model is incorporated to account for the absorption of the solar radiation by the working fluid and the absorber plate in the channel. It is found that the performance parameter improves considerably for the absorbing plate located at the channel bottom. The pump power loss parameter becomes the highest for the absorber plate location at the mid-height of the channel.

  19. Capturing molecular structural dynamics by 100 ps time-resolved X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Sato, Tokushi; Nozawa, Shunsuke; Ichiyanagi, Kohei; Tomita, Ayana; Chollet, Matthieu; Ichikawa, Hirohiko; Fujii, Hiroshi; Adachi, Shin-ichi; Koshihara, Shin-ya

    2009-01-01

    An experimental set-up for time-resolved X-ray absorption spectroscopy with 100 ps time resolution at beamline NW14A at the Photon Factory Advanced Ring is presented. An experimental set-up for time-resolved X-ray absorption spectroscopy with 100 ps time resolution at beamline NW14A at the Photon Factory Advanced Ring is presented. The X-ray positional active feedback to crystals in a monochromator combined with a figure-of-merit scan of the laser beam position has been utilized as an essential tool to stabilize the spatial overlap of the X-ray and laser beams at the sample position. As a typical example, a time-resolved XAFS measurement of a photo-induced spin crossover reaction of the tris(1,10-phenanthrorine)iron(II) complex in water is presented

  20. Insights into the physics and chemistry of chalcogenides obtained from x-ray absorption spectroscopy

    Science.gov (United States)

    Kolobov, Alexander V.; Fons, Paul

    2017-12-01

    In this review, after a brief description of the underlying principles of x-ray absorption spectroscopy, we describe the results that enable one to obtain fundamental new insights into the rich physics and chemistry of chalcogenides. We start with chalcogenide glasses taking the readers from the structure of amorphous selenium and confined single Se chains and carry on to photo-induced structural changes. We subsequently describe application of EXAFS to monolayers of transition-metal dichalcogenides. The review is concluded by the results that were seminal to understand the phase-transition mechanism in so-called phase-change alloys that are widely used in optical and non-volatile memory devices. We place special accent on the conclusions that were only possible to draw based on the local nature of x-ray absorption spectroscopy.

  1. An Accurate Method for Computing the Absorption of Solar Radiation by Water Vapor

    Science.gov (United States)

    Chou, M. D.

    1980-01-01

    The method is based upon molecular line parameters and makes use of a far wing scaling approximation and k distribution approach previously applied to the computation of the infrared cooling rate due to water vapor. Taking into account the wave number dependence of the incident solar flux, the solar heating rate is computed for the entire water vapor spectrum and for individual absorption bands. The accuracy of the method is tested against line by line calculations. The method introduces a maximum error of 0.06 C/day. The method has the additional advantage over previous methods in that it can be applied to any portion of the spectral region containing the water vapor bands. The integrated absorptances and line intensities computed from the molecular line parameters were compared with laboratory measurements. The comparison reveals that, among the three different sources, absorptance is the largest for the laboratory measurements.

  2. The AM1.5 absorption factor of thin-film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Santbergen, R.; Goud, J.M.; van Zolingen, R.J.C. [Eindhoven University of Technology, Department of Mechanical Engineering, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Zeman, M. [Delft University of Technology, EEC-DIMES, P.O. Box 5053, 2600 GB Delft (Netherlands); van Roosmalen, J.A.M. [Energy Research Centre of The Netherlands ECN, P.O. Box 1, 1755 ZG Petten (Netherlands)

    2010-05-15

    Both for photovoltaic and photovoltaic/thermal applications insight is required in the mechanisms that determine the effective absorption factor A{sub eff}. A{sub eff} is the part of the incident irradiation that is converted into heat, taking into account that part of the energy is withdrawn as electricity. A{sub eff} was studied for five different solar cell technologies using an optical simulation model and ranges from 74% for single junction amorphous silicon solar cells to 82% for CIGS solar cells. The simulations also show that the longer wavelength part of the spectrum is hardly absorbed by the active semiconductors, but mostly by free carrier absorption in the transparent conductive oxide film present in these devices. (author)

  3. Diagnosis of laser ablated carbon particles measured by time-resolved X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Miyashita, Atsumi; Yoda, Osamu; Ohyanagi, T.; Murakami, K.

    1995-01-01

    The time and space resolved properties of laser ablated carbon particles were measured by X-ray absorption spectroscopy using LPX as an X-ray source. The energy density of the irradiation laser on the sample was in the range of 0.5-20J/cm 2 and the time delay was varied between 0 and 120ns. The absorption spectra exhibited several peaks originated from level to level transitions and an intense broad absorption in the energy range of C-K edge. At a delay time of 120ns, the absorption peak from 1s→2p transition of neutral carbon atom (C 0 ), C - , C + and C 2+ ions were observed. The absorption peak from C 0 was stronger as the probing position was closer to the sample surface and decreased rapidly with distance from the sample surface. The absorption peak C 2+ ion was observed only at comparatively distant positions from surface. The maximum speeds of highly charged ions were faster than that of neutral atoms and negative charged ions. The neutral atom and lower charged ions were emitted from the sample even after laser irradiation. The spatial distributions of the laser ablated carbon particles in the localized helium gas environment were measured. In the helium gas environment, the ablation plume was depressed by the helium cloud generated on the top of ablation plume. (author)

  4. Atmospheric extinction in solar tower plants: the Absorption and Broadband Correction for MOR measurements

    Science.gov (United States)

    Hanrieder, N.; Wilbert, S.; Pitz-Paal, R.; Emde, C.; Gasteiger, J.; Mayer, B.; Polo, J.

    2015-05-01

    Losses of reflected Direct Normal Irradiance due to atmospheric extinction in concentrating solar tower plants can vary significantly with site and time. The losses of the direct normal irradiance between the heliostat field and receiver in a solar tower plant are mainly caused by atmospheric scattering and absorption by aerosol and water vapor concentration in the atmospheric boundary layer. Due to a high aerosol particle number, radiation losses can be significantly larger in desert environments compared to the standard atmospheric conditions which are usually considered in raytracing or plant optimization tools. Information about on-site atmospheric extinction is only rarely available. To measure these radiation losses, two different commercially available instruments were tested and more than 19 months of measurements were collected at the Plataforma Solar de Almería and compared. Both instruments are primarily used to determine the meteorological optical range (MOR). The Vaisala FS11 scatterometer is based on a monochromatic near-infrared light source emission and measures the strength of scattering processes in a small air volume mainly caused by aerosol particles. The Optec LPV4 long-path visibility transmissometer determines the monochromatic attenuation between a light-emitting diode (LED) light source at 532 nm and a receiver and therefore also accounts for absorption processes. As the broadband solar attenuation is of interest for solar resource assessment for Concentrating Solar Power (CSP), a correction procedure for these two instruments is developed and tested. This procedure includes a spectral correction of both instruments from monochromatic to broadband attenuation. That means the attenuation is corrected for the actual, time-dependent by the collector reflected solar spectrum. Further, an absorption correction for the Vaisala FS11 scatterometer is implemented. To optimize the Absorption and Broadband Correction (ABC) procedure, additional

  5. Charge Carrier Dynamics in Transition Metal Oxides Studied by Femtosecond Transient Extreme Ultraviolet Absorption Spectroscopy

    OpenAIRE

    Jiang, Chang-Ming

    2015-01-01

    With the ability to disentangle electronic transitions that occur on different elements and local electronic structures, time-resolved extreme ultraviolet (XUV) spectroscopy has emerged as a powerful tool for studying ultrafast dynamics in condensed phase systems. In this dissertation, a visible-pump/XUV-probe transient absorption apparatus with femtosecond resolution was constructed to investigate the carrier relaxation dynamics in semiconductors after photo-excitation. This includes timesca...

  6. Atomic structure of machined semiconducting chips: An x-ray absorption spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Paesler, M.; Sayers, D.

    1988-12-01

    X-ray absorption spectroscopy (XAS) has been used to examine the atomic structure of chips of germanium that were produced by single point diamond machining. It is demonstrated that although the local (nearest neighbor) atomic structure is experimentally quite similar to that of single crystal specimens information from more distant atoms indicates the presence of considerable stress. An outline of the technique is given and the strength of XAS in studying the machining process is demonstrated.

  7. Time-resolved tunable diode laser absorption spectroscopy of pulsed plasma

    Czech Academy of Sciences Publication Activity Database

    Adámek, Petr; Olejníček, Jiří; Čada, Martin; Kment, Š.; Hubička, Zdeněk

    2013-01-01

    Roč. 38, č. 14 (2013), s. 2428-2430 ISSN 0146-9592 R&D Projects: GA MŠk LH12045; GA ČR(CZ) GAP205/11/0386; GA MŠk LD12002; GA MŠk LH12043 Institutional support: RVO:68378271 Keywords : diode lasers * plasma diagnostics * absorption spectroscopy * time resolved Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.179, year: 2013

  8. UV Absorption Spectroscopy in Water-Filled Antiresonant Hollow Core Fibers for Pharmaceutical Detection

    OpenAIRE

    Mona Nissen; Brenda Doherty; Jonas Hamperl; Jens Kobelke; Karina Weber; Thomas Henkel; Markus A. Schmidt

    2018-01-01

    Due to a worldwide increased use of pharmaceuticals and, in particular, antibiotics, a growing number of these substance residues now contaminate natural water resources and drinking supplies. This triggers a considerable demand for low-cost, high-sensitivity methods for monitoring water quality. Since many biological substances exhibit strong and characteristic absorption features at wavelengths shorter than 300 nm, UV spectroscopy presents a suitable approach for the quantitative identifica...

  9. Investigation of Diode Pumped Alkali Laser Atmospheric Transmission Using Tunable Diode Laser Absorption Spectroscopy

    Science.gov (United States)

    2012-09-01

    reflectivity of the background. This device can be configured to detect hydrogen fluoride , hydrogen sulfide, or methane. Other related papers with the...absorption spectroscopy and in-situ gas chromatography ”. volume 3758, 109–115. SPIE, October 1999. 42. Hunsmann, S., K. Wunderle, S. Wagner, U. Rascher, U...black), 1 atm He (dashed black) and 10 atm He (short dash back), each with a buffer gas mixture including 100 Torr C2H6. Gain profiles are normalized

  10. Procedure for intercomparison study for trace elements determination in soil samples by absorption spectroscopy

    International Nuclear Information System (INIS)

    Sanchez P, L.A.; Benavides M, A.M.

    1996-01-01

    In the environmental sampling analysis there is very important to establish an adequate methodologies on the laboratories for improvement the quality of the results obtained, so the establishment of a qualified laboratories network for environmental analysis. The objective of this work is to show the working plan for the analysis of eight elements on a Russian soil sample for an interlaboratory comparison with IAEA, by the Absorption spectroscopy technique using flame. (Author)

  11. Automotive absorption air conditioner utilizing solar and motor waste heat

    Science.gov (United States)

    Popinski, Z. (Inventor)

    1981-01-01

    In combination with the ground vehicles powered by a waste heat generating electric motor, a cooling system including a generator for driving off refrigerant vapor from a strong refrigerant absorbant solution is described. A solar collector, an air-cooled condenser connected with the generator for converting the refrigerant vapor to its liquid state, an air cooled evaporator connected with the condenser for returning the liquid refrigerant to its vapor state, and an absorber is connected to the generator and to the evaporator for dissolving the refrigerant vapor in the weak refrigerant absorbant solution, for providing a strong refrigerant solution. A pump is used to establish a pressurized flow of strong refrigerant absorbant solution from the absorber through the electric motor, and to the collector.

  12. Remote Thermal IR Spectroscopy of our Solar System

    Science.gov (United States)

    Kostiuk, Theodor; Hewagama, Tilak; Goldstein, Jeffrey; Livengood, Timothy; Fast, Kelly

    1999-01-01

    Indirect methods to detect extrasolar planets have been successful in identifying a number of stars with companion planets. No direct detection of an extrasolar planet has yet been reported. Spectroscopy in the thermal infrared region provides a potentially powerful approach to detection and characterization of planets and planetary systems. We can use knowledge of our own solar system, its planets and their atmospheres to model spectral characteristics of planets around other stars. Spectra derived from modeling our own solar system seen from an extrasolar perspective can be used to constrain detection strategies, identification of planetary class (terrestrial vs. gaseous) and retrieval of chemical, thermal and dynamical information. Emission from planets in our solar system peaks in the thermal infrared region, approximately 10 - 30 microns, substantially displaced from the maximum of the much brighter solar emission in the visible near 0.5 microns. This fact provides a relatively good contrast ratio to discriminate between stellar (solar) and planetary emission and optimize the delectability of planetary spectra. Important molecular constituents in planetary atmospheres have rotational-vibrational spectra in the thermal infrared region. Spectra from these molecules have been well characterized in the laboratory and studied in the atmospheres of solar system planets from ground-based and space platforms. The best example of such measurements are the studies with Fourier transform spectrometers, the Infrared Interferometer Spectrometers (IRIS), from spacecraft: Earth observed from NIMBUS 8, Mars observed from Mariner 9, and the outer planets observed from Voyager spacecraft. An Earth-like planet is characterized by atmospheric spectra of ozone, carbon dioxide, and water. Terrestrial planets have oxidizing atmospheres which are easily distinguished from reducing atmospheres of gaseous giant planets which lack oxygen-bearing species and are characterized by spectra

  13. Significant enhancement of optical absorption through nano-structuring of copper based oxide semiconductors: possible future materials for solar energy applications.

    Science.gov (United States)

    Bhaumik, Anagh; Shearin, Austin M; Patel, Rishi; Ghosh, Kartik

    2014-06-14

    The optical absorption coefficient is a crucial parameter in determining solar cell efficiency under operational conditions. It is well known that inorganic nanocrystals are a benchmark model for solar cell nanotechnology, given that the tunability of optical properties and stabilization of specific phases are uniquely possible at the nanoscale. A hydrothermal method was employed to fabricate nanostructured copper oxides where the shape, size and phase were tailored by altering the growth parameters, namely the base media used, the reaction temperature, and the reaction time. The nano crystalline structures, phases, morphology, molecular vibrational modes, and optical properties were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, photoluminescence (PL), and UV-vis spectroscopy. A significantly large optical absorption coefficient, of the order of twice that of Si in the visible range, was observed in a particular phase mixture of nanostructured copper oxides. An optical absorption coefficient of 7.05 10(+5) cm(-1) at 525 nm was observed in a particular nanostructured phase mixture of copper oxides which is appreciably larger than commercially pure CuO (1.19 10(+5) cm(-1)) and Si (1.72 10(+5) cm(-1)). A possible mechanism of formation of phase mixtures and morphology of copper oxides has also been discussed, which opens up a roadmap in synthesis of similar morphology nanostructures for efficient solar cells.

  14. Photothermal response of CVD synthesized carbon (nanospheres/aqueous nanofluids for potential application in direct solar absorption collectors: a preliminary investigation

    Directory of Open Access Journals (Sweden)

    Poinern GE

    2012-07-01

    Full Text Available Gérrard Eddy Jai Poinern,1 Sridevi Brundavanam,1 Monaliben Shah,1 Iafeta Laava,2 Derek Fawcett11Murdoch Applied Nanotechnology Research Group, 2Department of Physics, Energy Studies and Nanotechnology, Murdoch University, Perth, AustraliaAbstract: Direct-absorption solar collectors have the potential to offer an unlimited source of renewable energy with minimal environmental impact. Unfortunately, their performance is limited by the absorption efficiency of the working fluid. Nanoparticles of functionalized carbon nanospheres (CNS have the potential to improve the photothermal properties of the working fluid. CNS are produced by the pyrolysis of acetylene gas in a tube-based electric furnace/chemical vapor deposition apparatus. The reaction takes place at 1000°C in the presence of nitrogen gas without the use of a catalyst. The synthesized CNS were examined and characterized using field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction spectroscopy, Raman spectroscopy, thermal gravimetric analysis, and ultraviolet-visible analysis. The CNS powders with a mean particle size of 210 nm were then functionalized using tetraethylammonium hydroxide ([C2H5]4 N[OH] and used to produce a series of aqueous nanofluids with varying mass content. The photothermal response of both the nanofluids and films composed of CNS were investigated under 1000 W/m2 solar irradiation.Keywords: solar absorption, carbon nanospheres, nanofluids, photothermal

  15. X-RAY ABSORPTION SPECTROSCOPY OF YB3+-DOPED OPTICAL FIBERS

    Energy Technology Data Exchange (ETDEWEB)

    Citron, Robert; Kropf, A.J.

    2008-01-01

    Optical fibers doped with Ytterbium-3+ have become increasingly common in fiber lasers and amplifiers. Yb-doped fibers provide the capability to produce high power and short pulses at specific wavelengths, resulting in highly effective gain media. However, little is known about the local structure, distribution, and chemical coordination of Yb3+ in the fibers. This information is necessary to improve the manufacturing process and optical qualities of the fibers. Five fibers doped with Yb3+ were studied using Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy and X-ray Absorption Near Edge Spectroscopy (XANES), in addition to Yb3+ mapping. The Yb3+ distribution in each fiber core was mapped with 2D and 1D intensity scans, which measured X-ray fluorescence over the scan areas. Two of the five fibers examined showed highly irregular Yb3+ distributions in the core center. In four of the five fibers Yb3+ was detected outside of the given fiber core dimensions, suggesting possible Yb3+ diffusion from the core, manufacturing error, or both. X-ray absorption spectroscopy (XAS) analysis has so far proven inconclusive, but did show that the fibers had differing EXAFS spectra. The Yb3+ distribution mapping proved highly useful, but additional modeling and examination of fiber preforms must be conducted to improve XAS analysis, which has been shown to have great potential for the study of similar optical fi bers.

  16. Enhanced photon absorption in spiral nanostructured solar cells using layered 2D materials.

    Science.gov (United States)

    Tahersima, Mohammad H; Sorger, Volker J

    2015-08-28

    Recent investigations of semiconducting two-dimensional (2D) transition metal dichalcogenides have provided evidence for strong light absorption relative to its thickness attributed to high density of states. Stacking a combination of metallic, insulating, and semiconducting 2D materials enables functional devices with atomic thicknesses. While photovoltaic cells based on 2D materials have been demonstrated, the reported absorption is still just a few percent of the incident light due to their sub-wavelength thickness leading to low cell efficiencies. Here we show that taking advantage of the mechanical flexibility of 2D materials by rolling a molybdenum disulfide (MoS(2))/graphene (Gr)/hexagonal boron nitride stack to a spiral solar cell allows for optical absorption up to 90%. The optical absorption of a 1 μm long hetero-material spiral cell consisting of the aforementioned hetero stack is about 50% stronger compared to a planar MoS(2) cell of the same thickness; although the volumetric absorbing material ratio is only 6%. A core-shell structure exhibits enhanced absorption and pronounced absorption peaks with respect to a spiral structure without metallic contacts. We anticipate these results to provide guidance for photonic structures that take advantage of the unique properties of 2D materials in solar energy conversion applications.

  17. X-ray absorption and X-ray emission spectroscopy theory and applications

    CERN Document Server

    Lamberti, Carlo

    2016-01-01

    During the last two decades, remarkable and often spectacular progress has been made in the methodological and instrumental aspects of x–ray absorption and emission spectroscopy. This progress includes considerable technological improvements in the design and production of detectors especially with the development and expansion of large-scale synchrotron reactors All this has resulted in improved analytical performance and new applications, as well as in the perspective of a dramatic enhancement in the potential of x–ray based analysis techniques for the near future. This comprehensive two-volume treatise features articles that explain the phenomena and describe examples of X–ray absorption and emission applications in several fields, including chemistry, biochemistry, catalysis, amorphous and liquid systems, synchrotron radiation, and surface phenomena. Contributors explain the underlying theory, how to set up X–ray absorption experiments, and how to analyze the details of the resulting spectra. X-R...

  18. Iodine flow rate measurement for COIL with the chemical iodine generator based on absorption spectroscopy

    Science.gov (United States)

    Zhao, Weili; Zhang, Yuelong; Zhang, Peng; Xu, Mingxiu; Jin, Yuqi; Sang, Fengting

    2015-02-01

    A dual-components absorption method based on absorption spectroscopy was described in the paper. It can easily eliminate the influence of the serious contamination and aerosol scattering on IFR measurement by utilizing the absorptions of iodine vapor and chlorine on two different wavelengths respectively. According to the character that there is no other gaseous product in the reaction besides iodine vapor, IFR in real time can be obtained by the connections of the pressure and the flow rate among chlorine remainder, iodine vapor, and the buffer gas. We used this method to measure IFR for the first time at the exit of a chemical iodine generator. The average of IFR is coincident with that calculated by chemical weighting mass.

  19. Novel Semi-Parametric Algorithm for Interference-Immune Tunable Absorption Spectroscopy Gas Sensing

    Directory of Open Access Journals (Sweden)

    Umberto Michelucci

    2017-10-01

    Full Text Available One of the most common limits to gas sensor performance is the presence of unwanted interference fringes arising, for example, from multiple reflections between surfaces in the optical path. Additionally, since the amplitude and the frequency of these interferences depend on the distance and alignment of the optical elements, they are affected by temperature changes and mechanical disturbances, giving rise to a drift of the signal. In this work, we present a novel semi-parametric algorithm that allows the extraction of a signal, like the spectroscopic absorption line of a gas molecule, from a background containing arbitrary disturbances, without having to make any assumption on the functional form of these disturbances. The algorithm is applied first to simulated data and then to oxygen absorption measurements in the presence of strong fringes.To the best of the authors’ knowledge, the algorithm enables an unprecedented accuracy particularly if the fringes have a free spectral range and amplitude comparable to those of the signal to be detected. The described method presents the advantage of being based purely on post processing, and to be of extremely straightforward implementation if the functional form of the Fourier transform of the signal is known. Therefore, it has the potential to enable interference-immune absorption spectroscopy. Finally, its relevance goes beyond absorption spectroscopy for gas sensing, since it can be applied to any kind of spectroscopic data.

  20. Novel Semi-Parametric Algorithm for Interference-Immune Tunable Absorption Spectroscopy Gas Sensing.

    Science.gov (United States)

    Michelucci, Umberto; Venturini, Francesca

    2017-10-07

    One of the most common limits to gas sensor performance is the presence of unwanted interference fringes arising, for example, from multiple reflections between surfaces in the optical path. Additionally, since the amplitude and the frequency of these interferences depend on the distance and alignment of the optical elements, they are affected by temperature changes and mechanical disturbances, giving rise to a drift of the signal. In this work, we present a novel semi-parametric algorithm that allows the extraction of a signal, like the spectroscopic absorption line of a gas molecule, from a background containing arbitrary disturbances, without having to make any assumption on the functional form of these disturbances. The algorithm is applied first to simulated data and then to oxygen absorption measurements in the presence of strong fringes.To the best of the authors' knowledge, the algorithm enables an unprecedented accuracy particularly if the fringes have a free spectral range and amplitude comparable to those of the signal to be detected. The described method presents the advantage of being based purely on post processing, and to be of extremely straightforward implementation if the functional form of the Fourier transform of the signal is known. Therefore, it has the potential to enable interference-immune absorption spectroscopy. Finally, its relevance goes beyond absorption spectroscopy for gas sensing, since it can be applied to any kind of spectroscopic data.

  1. In-situ Characterization of Molecular Processes in Liquids by Ultrafast X-ray Absorption Spectroscopy

    Science.gov (United States)

    Chergui, Majed

    The need to visualize molecular and electronic structure in the course of a chemical reaction, a phase transformation a biological function has been the dream of scientists for decades. The development of time-resolved X-ray and electron based methods is making this true. X-ray absorption spectroscopy is ideal for the study of structural dynamics in liquids, because it can be implemented in amorphous media and it is chemically selective. Using X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) in laser pump/X-ray probe experiments allows the retrieval of the local geometric structure of the system under study, but also the underlying photoinduced electronic structure changes that drive the structural dynamics. We review the recent development in picosecond and femtosecond X-ray absorption spectroscopy applied to molecular systems in solution: examples on ultrafast photoinduced processes such as intramolecular electron transfer, high-to-low spin change, bond formation and water dynamics are presented.

  2. Observation of the subgap optical absorption in polymer-fullerene blend solar cells

    Czech Academy of Sciences Publication Activity Database

    Goris, L.; Poruba, Aleš; Hoďáková, Lenka; Vaněček, Milan; Haenen, K.; Nesladek, M.; Wagner, P.; Vanderzande, D.; De Schepper, L.; Manca, J.V.

    2006-01-01

    Roč. 88, č. 5 (2006), 052113/1-052113/3 ISSN 0003-6951 Grant - others:BIL Cooperation Flanders-Czech Republic(BE) BOF04B03 Institutional research plan: CEZ:AV0Z10100521 Keywords : solar cells * optical spectroscopy * polymer -fullerene bulk heterojunctions Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.977, year: 2006

  3. Autonomous long-term trace gas measurements using Long-Path Differential Optical Absorption Spectroscopy

    Science.gov (United States)

    Nasse, Jan-Marcus; Pöhler, Denis; Eger, Philipp; Schmitt, Stefan; Friess, Udo; Platt, Ulrich

    2017-04-01

    Long-Path DOAS (Differential Optical Absorption Spectroscopy) is a well-established, very specific and reliable remote sensing technique for the observation of a large variety of trace gases. So far DOAS has been mostly applied in the UV-Vis spectral region; detectable species are for example ClO, OClO, BrO, OBrO, IO, OIO, I2, OIO, O3, formaldehyde, glyoxal, NO2, H2O, O4, or SO2. In the Long Path DOAS setup, a dedicated light source and a measurement path of up to 10 km between a telescope and a reflector yield continuous path averaged concentrations independent of solar radiation and still on scales below the ground pixel sizes of satellite instruments. Here we present an advanced LP-DOAS instrument incorporating several technical improvements to a setup that allows for the first time autonomous and continuous long term measurements with very high measurement accuracy necessary for the measurement of low trace gas concentrations. The setup uses an optical fiber bundle in the telescope for transmission and reception of the measurement signal. The traditional Xe-arc lamp has been replaced by a Laser Driven Light Source with a long life time and very good optical stability. Using this light source also allows an improved wavelength selective coupling from light source into the fiber which reduces stray light. The coupling and configuration of the optical fiber was optimised compared to previous designs to maximise light throughput and reduce stray light. Additionally, the fibers were treated in order to reduce noise caused by irregular grating illumination. These changes drastically lower detection limits (e.g. to 1 pptv for BrO or 8 pptv for ClO) and improve the long-term reliability. To facilitate an autonomous operation, the measurement software incorporates features such as an automatic reflector search and intensity optimisation as well as a selection from the available measurement paths based on atmospheric visibility. Since January 2016, we are successfully

  4. I20; the Versatile X-ray Absorption spectroscopy beamline at Diamond Light Source

    International Nuclear Information System (INIS)

    Diaz-Moreno, S; Hayama, S; Amboage, M; Freeman, A; Sutter, J; Duller, G

    2009-01-01

    The Versatile Spectroscopy beamline at Diamond Light Source, I20, is currently under construction and aims to begin operation in late 2009 and early 2010. The beamline aims to cover applications from physics, chemistry and biology through materials, environmental and geological science. Three very distinctive modes of operation will be offered at the beamline: scanning X-ray Absorption spectroscopy (XAS), XAS in dispersive mode, and X-ray emission spectroscopy (XES). To achieve this, the beamline has been designed around two independent experimental end-stations operating from a pair of canted wigglers located in a 5m diamond straight section. One branch of the beamline will deliver monochromatic x-ray radiation of high spectral purity to one of the experimental hutches, whilst the other branch will constitute an energy dispersive spectrometer. The novel design of the beamline allows both branches to operate simultaneously.

  5. Ligand-field symmetry effects in Fe(ii) polypyridyl compounds probed by transient X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Hana; Strader, Matthew L.; Hong, Kiryong; Jamula, Lindsey; Gullikson, Eric M.; Kim, Tae Kyu; de Groot, Frank M. F.; McCusker, James K.; Schoenlein, Robert W.; Huse, Nils

    2012-01-01

    Ultrafast excited-state evolution in polypyridyl FeII complexes are of fundamental interest for understanding the origins of the sub-ps spin-state changes that occur upon photoexcitation of this class of compounds as well as for the potential impact such ultrafast dynamics have on incorporation of these compounds in solar energy conversion schemes or switchable optical storage technologies. We have demonstrated that ground-state and, more importantly, ultrafast time-resolved x-ray absorption methods can offer unique insights into the interplay between electronic and geometric structure that underpin the photo-induced dynamics of this class of compounds. The present contribution examines in greater detail how the symmetry of the ligand field surrounding the metal ion can be probed using these x-ray techniques. In particular, we show that steady-state K-edge spectroscopy of the nearest-neighbour nitrogen atoms reveals the characteristic chemical environment of the respective ligands and suggests an interesting target for future charge-transfer femtosecond and attosecond spectroscopy in the x-ray water window.

  6. Solar-assisted absorption air-conditioning systems in buildings: Control strategies and operational modes

    International Nuclear Information System (INIS)

    Shirazi, Ali; Pintaldi, Sergio; White, Stephen D.; Morrison, Graham L.; Rosengarten, Gary; Taylor, Robert A.

    2016-01-01

    Highlights: • A simulation model of a solar driven absorption chiller is developed in detail. • Three control strategies were proposed in the solar loop of the plant. • Series and parallel auxiliary heater arrangements were investigated. • The results showed the auxiliary-heater in parallel outperformed the series one. • Solar fraction can be increased by 20% by implementing the proposed configuration. - Abstract: Solar-assisted cooling technology has enormous potential for air-conditioning applications since both solar energy supply and cooling energy demand are well correlated. Unfortunately, market uptake of solar cooling technologies has been slow due to the high capital cost and limited design/operational experience. In the present work, different designs and operational modes for solar heating and cooling (SHC) absorption chiller systems are investigated and compared in order to identify the preferred design strategies for these systems. Three control scenarios are proposed for the solar collector loop. The first uses a constant flow pump, while the second and third control schemes employ a variable speed pump, where the solar collector (SC) set-point temperature could be either fixed or adjusted to the required demand. Series and parallel arrangements, between the auxiliary heater and the storage tank, have been examined in detail from an energy efficiency perspective. A simulation model for different system layouts is developed in the transient system simulation environment (TRNSYS, Version 17). Simulation results revealed that the total solar fraction of the plant is increased by up to 11% when a variable speed solar loop pump is used to achieve a collector set-point temperature adjusted according to the building load demand. Another significant finding of this study is that a parallel configuration for the auxiliary heater out-performs a conventional series configuration. The yearly performance of an auxiliary heater in parallel with the storage

  7. Simulation study on the performance of solar/natural gas absorption cooling chillers

    International Nuclear Information System (INIS)

    Gomri, Rabah

    2013-01-01

    Highlights: ► The overall performance of the solar/natural gas chillers is analysed and discussed. ► The system operates in regions with abundant solar energy and cheap natural gas. ► The maximum daily cover of solar energy (between time of day 8 and 17) is about 58%. ► An optimum generator temperature gives a minimum number of flat plate collectors. ► This system compensates the peak-valley load difference and reduces CO 2 gas emissions. - Abstract: Solar radiation is a clean form of energy and solar cooling systems is one of the technologies which allow obtaining an important energy saving. Natural gas is a cheaper fuel than oil. It also burns cleaner than oil. Natural gas and renewable energy are complementary and in the future, the alignment of natural gas and renewable energy may be the most effective way to service the demand for clean energy. This paper presents a numerical study of solar/natural gas single effect lithium bromide absorption chillers. The development of this system is based on hot water chiller. As auxiliary power, fire from the natural gas burners is used to heat the hot water on its way to the generator. The overall performance of the absorption chiller system is analysed and discussed. For an evaporator temperature of 5 °C and when the condenser temperature is varied from 28 °C to 36 °C and generator temperatures is varied from 54 to 83 °C the maximum COP is 0.82 and the maximum exergetic efficiency is about 30%. For a given condenser temperature there is an optimum generator temperature for which the number of flat plate collectors is minimum. This optimum generator temperature corresponds to the generator temperature giving the maximum COP and exergy efficiency of the absorption cooling system. The solar/natural gas single effect lithium bromide absorption chillers, using solar energy as the energy source with only limited amount of gas as auxiliary power, not only reduces greatly the cost for electricity and operates in

  8. Optimization of a solar driven absorption refrigerator in the transient regime

    International Nuclear Information System (INIS)

    Hamed, Mouna; Fellah, Ali; Ben Brahim, Ammar

    2012-01-01

    Highlights: ► Dynamic behavior of a solar absorption refrigerator endoreversible model. ► Using the principles of classical thermodynamics, mass and heat transfers. ► Minimizing heat exchange time to reach maximum performances. ► Major influence of the collector temperature on the model’s characteristics. ► Analogous effects of both the thermal load and the thermal conductance. -- Abstract: This contribution deals with the theoretical study in dynamic mode of an absorption refrigerator endoreversible model. The system is a cold generating station driven by solar energy. The main elements of the cycle are a refrigerated space, an absorption refrigerator and a solar collector form. A mathematical model is developed. It combines the classical thermodynamics and mass and heat transfers principles. The numerical simulation is made for different operating and conceptual conditions. A global minimizing time optimization is performed in view to reach maximum performances. Appropriate dimensionless groups are defined. The results are presented in normalized charts for general applications. The collector temperature presents major influence on the conceptual and functional characteristics compared to the stagnation temperature influence. On the other hand the thermal load in the refrigerated space and the thermal conductance of the walls has analogous effects, therefore important to be considered in actual design. As a result, the model is expected to be a useful tool for simulation, design, and optimization of solar collector based energy systems.

  9. Dynamic Optoelectronic Properties in Perovskite Oxide Thin Films Measured with Ultrafast Transient Absorption & Reflectance Spectroscopy

    Science.gov (United States)

    Smolin, Sergey Y.

    Ultrafast transient absorption and reflectance spectroscopy are foundational techniques for studying photoexcited carrier recombination mechanisms, lifetimes, and charge transfer rates. Because quantifying photoexcited carrier dynamics is central to the intelligent design and improvement of many solid state devices, these transient optical techniques have been applied to a wide range of semiconductors. However, despite their promise, interpretation of transient absorption and reflectance data is not always straightforward and often relies on assumptions of physical processes, especially with respect to the influence of heating. Studying the material space of perovskite oxides, the careful collection, interpretation, and analysis of ultrafast data is presented here as a guide for future research into novel semiconductors. Perovskite oxides are a class of transition metal oxides with the chemical structure ABO3. Although traditionally studied for their diverse physical, electronic, and magnetic properties, perovskite oxides have gained recent research attention as novel candidates for light harvesting applications. Indeed, strong tunable absorption, unique interfacial properties, and vast chemical flexibility make perovskite oxides a promising photoactive material system. However, there is limited research characterizing dynamic optoelectronic properties, such as recombination lifetimes, which are critical to know in the design of any light-harvesting device. In this thesis, ultrafast transient absorption and reflectance spectroscopy was used to understand these dynamic optoelectronic properties in highquality, thin (gap of LFO at 2.4 eV and at the higher energy absorption edge at 3.5 eV. Using a combination of temperature-dependent, variable-angle spectroscopic ellipsometry and time-resolved ultrafast optical spectroscopy on a type I heterostructure, we clarify thermal and electronic contributions to spectral transients in LaFeO3. Upon comparison to thermally

  10. Cavity ring-down spectroscopy (CRDS) system for measuring atmospheric mercury using differential absorption

    Science.gov (United States)

    Pierce, A.; Obrist, D.; Moosmuller, H.; Moore, C.

    2012-04-01

    Atmospheric elemental mercury (Hg0) is a globally pervasive element that can be transported and deposited to remote ecosystems where it poses — particularly in its methylated form — harm to many organisms including humans. Current techniques for measurement of atmospheric Hg0 require several liters of sample air and several minutes for each analysis. Fast-response (i.e., 1 second or faster) measurements would improve our ability to understand and track chemical cycling of mercury in the atmosphere, including high frequency Hg0 fluctuations, sources and sinks, and chemical transformation processes. We present theory, design, challenges, and current results of our new prototype sensor based on cavity ring-down spectroscopy (CRDS) for fast-response measurement of Hg0 mass concentrations. CRDS is a direct absorption technique that implements path-lengths of multiple kilometers in a compact absorption cell using high-reflectivity mirrors, thereby improving sensitivity and reducing sample volume compared to conventional absorption spectroscopy. Our sensor includes a frequency-doubled, dye-laser emitting laser pulses tunable from 215 to 280 nm, pumped by a Q-switched, frequency tripled Nd:YAG laser with a pulse repetition rate of 50 Hz. We present how we successfully perform automated wavelength locking and stabilization of the laser to the peak Hg0 absorption line at 253.65 nm using an external isotopically-enriched mercury (202Hg0) cell. An emphasis of this presentation will be on the implementation of differential absorption measurement whereby measurements are alternated between the peak Hg0 absorption wavelength and a nearby wavelength "off" the absorption line. This can be achieved using a piezo electric tuning element that allows for pulse-by-pulse tuning and detuning of the laser "online" and "offline" of the Hg absorption line, and thereby allows for continuous correction of baseline extinction losses. Unexpected challenges with this approach included

  11. A survey of TiOλ567 nm absorption in solar-type stars

    Science.gov (United States)

    Azizi, Fatemeh; Mirtorabi, Mohammad Taghi

    2018-04-01

    Molecular absorption bands are estimators of stellar activity and spot cycles on magnetically active stars. We have previously introduced a new colour index that compares absorption strength of the titanium oxide (TiO) at 567 nm with nearby continuum. In this paper, we implement this index to measure long-term activity variations and the statistical properties of the index in a sample of 302 solar-type stars from the High Accuracy Radial Velocity Planet search Spectrograph planet search programme. The results indicate a pattern of change in star's activity, covers a range of periods from 2 yr up to 17 yr.

  12. Hybrid solar receiver as a source of high-temperature medium for an absorption chiller supply

    Directory of Open Access Journals (Sweden)

    Przenzak Estera

    2016-01-01

    Full Text Available This article discusses the problems related with the cold production, i.e. energy efficiency of the process. The idea of solar cooling systems has been presented as the solution of the problem of big electricity demand. The paper discusses the principle of the operation of absorption chillers. Disadvantages and advantages of the solar cooling systems were discussed. The installation for manufacturing high-temperature heat based on solar collectors and concentrator of solar radiation constructed in AGH in Cracow has been presented. This installation is a first stage of projected, complete solar cooling system. The special attention is paid to the dedicated solar high-temperature heat receiver as a most important element of the system. The achieved values of temperature, power and efficiency depending on the working medium flow has been presented and discussed. The intensity of solar radiation during the measurements has been taken into account. Two versions of heat receiver were investigated: non-insulated and insulated with mineral wool. The obtained efficiency of the heat receiver (less than 30% is not satisfactory but possibility of improvements exist.

  13. Increasing Solar Absorption for Photocatalysis with Black Hydrogenated Titanium Dioxide Nanocrystals

    KAUST Repository

    Chen, X.

    2011-01-20

    When used as a photocatalyst, titanium dioxide (TiO 2) absorbs only ultraviolet light, and several approaches, including the use of dopants such as nitrogen, have been taken to narrow the band gap of TiO 2. We demonstrated a conceptually different approach to enhancing solar absorption by introducing disorder in the surface layers of nanophase TiO 2 through hydrogenation. We showed that disorder-engineered TiO 2 nanocrystals exhibit substantial solar-driven photocatalytic activities, including the photo-oxidation of organic molecules in water and the production of hydrogen with the use of a sacrificial reagent.

  14. SiNx layers on nanostructured Si solar cells: Effective for optical absorption and carrier collection

    International Nuclear Information System (INIS)

    Cho, Yunae; Kim, Eunah; Gwon, Minji; Kim, Dong-Wook; Park, Hyeong-Ho; Kim, Joondong

    2015-01-01

    We compared nanopatterned Si solar cells with and without SiN x layers. The SiN x layer coating significantly improved the internal quantum efficiency of the nanopatterned cells at long wavelengths as well as short wavelengths, whereas the surface passivation helped carrier collection of flat cells mainly at short wavelengths. The surface nanostructured array enhanced the optical absorption and also concentrated incoming light near the surface in broad wavelength range. Resulting high density of the photo-excited carriers near the surface could lead to significant recombination loss and the SiN x layer played a crucial role in the improved carrier collection of the nanostructured solar cells

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

    Science.gov (United States)

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

    2009-02-01

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

  16. UV-Vis Reflection-Absorption Spectroscopy at air-liquid interfaces.

    Science.gov (United States)

    Rubia-Payá, Carlos; de Miguel, Gustavo; Martín-Romero, María T; Giner-Casares, Juan J; Camacho, Luis

    2015-11-01

    UV-Visible Reflection-Absorption Spectroscopy (UVRAS) technique is reviewed with a general perspective on fundamental and applications. UVRAS is formally identical to IR Reflection-Absorption Spectroscopy (IRRAS), and therefore, the methodology developed for this IR technique can be applied in the UV-visible region. UVRAS can be applied to air-solid, air-liquid or liquid-liquid interfaces. This review focuses on the use of UVRAS for studying Langmuir monolayers. We introduce the theoretical framework for a successful understanding of the UVRAS data, and we illustrate the usage of this data treatment to a previous study from our group comprising an amphiphilic porphyrin. For ultrathin films with a thickness of few nm, UVRAS produces positive or negative bands when p-polarized radiation is used, depending on the incidence angle and the orientation of dipole absorption. UVRAS technique provides highly valuable information on tilt of chromophores at the air-liquid interface, and moreover allows the determination of optical parameters. We propose UVRAS as a powerful technique to investigate the in situ optical properties of Langmuir monolayers. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Surface arsenic speciation of a drinking-water treatment residual using X-ray absorption spectroscopy.

    Science.gov (United States)

    Makris, Konstantinos C; Sarkar, Dibyendu; Parsons, Jason G; Datta, Rupali; Gardea-Torresdey, Jorge L

    2007-07-15

    Drinking-water treatment residuals (WTRs) present a low-cost geosorbent for As-contaminated waters and soils. Previous work has demonstrated the high affinity of WTRs for As, but data pertaining to the stability of sorbed As is missing. Sorption/desorption and X-ray absorption spectroscopy (XAS), both XANES (X-ray absorption near edge structure) and EXAFS (extended X-ray absorption fine structure) studies, were combined to determine the stability of As sorbed by an Fe-based WTR. Arsenic(V) and As(III) sorption kinetics were biphasic in nature, sorbing >90% of the initial added As (15,000 mg kg(-1)) after 48 h of reaction. Subsequent desorption experiments with a high P load (7500 mg kg(-1)) showed negligible As desorption for both As species, approximately <3.5% of sorbed As; the small amount of desorbed As was attributed to the abundance of sorption sites. XANES data showed that sorption kinetics for either As(III) or As(V) initially added to solution had no effect on the sorbed As oxidation state. EXAFS spectroscopy suggested that As added either as As(III) or as As(V) formed inner-sphere mononuclear, bidentate complexes, suggesting the stability of the sorbed As, which was further corroborated by the minimum As desorption from the Fe-WTR.

  18. High speed engine gas thermometry by Fourier-domain mode-locked laser absorption spectroscopy.

    Science.gov (United States)

    Kranendonk, Laura A; An, Xinliang; Caswell, Andrew W; Herold, Randy E; Sanders, Scott T; Huber, Robert; Fujimoto, James G; Okura, Yasuhiro; Urata, Yasuhiro

    2007-11-12

    We present a novel method for low noise, high-speed, real-time spectroscopy to monitor molecular absorption spectra. The system is based on a rapidly swept, narrowband CW Fourier-domain mode-locked (FDML) laser source for spectral encoding in time and an optically time-multiplexed split-pulse data acquisition system for improved noise performance and sensitivity. An acquisition speed of ~100 kHz, a spectral resolution better than 0.1 nm over a wavelength range of ~1335-1373 nm and a relative noise level of ~5 mOD (~1% minimum detectable base-e absorbance) are achieved. The system is applied for crank-angle-resolved gas thermometry by H(2)O absorption spectroscopy in an engine motoring at 600 and 900 rpm with a precision of ~1%. Influences of various noise sources such as laser phase and intensity noise, trigger and synchronization jitter in the electronic detection system, and the accuracy of available H(2)O absorption databases are discussed.

  19. Molecular environment of iodine in naturally iodinated humic substances: Insight from X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Schlegel, Michel L.; Mercier-Bion, Florence; Barre, Nicole; Reiller, Pascal; Moulin, Valerie

    2006-01-01

    The molecular environment of iodine in reference inorganic and organic compounds, and in dry humic and fulvic acids (HAs and FAs) extracted from subsurface and deep aquifers was probed by iodine L-3-edge X-ray absorption spectroscopy. The X-ray absorption near-edge structure (XANES) of iodine spectra from HAs and FAs resembled those of organic references and displayed structural features consistent with iodine forming covalent bonds with organic molecules. Simulation of XANES spectra by linear combination of reference spectra suggested the predominance of iodine forming covalent bonds to aromatic rings (aromatic-bound iodine). Comparison of extended X-ray absorption fine structure (EXAFS) spectra of reference and samples further showed that iodine was surrounded by carbon shells at distances comparable to those for references containing aromatic-bound iodine. Quantitative analysis of EXAFS spectra indicated that iodine was bound to about one carbon at a distance d(I-C) of 2.01(4)-2.04(9) angstrom, which was comparable to the distances observed for aromatic-bound iodine in references (1.99(1)-2.07(6) angstrom), and significantly shorter than that observed for aliphatic-bound iodine (2.15(2)-2.16(2) angstrom). These results are in agreement with previous conclusions from X-ray photoelectron spectroscopy and from electro-spray ionization mass spectrometry. These results collectively suggest that the aromatic-bound iodine is stable in the various aquifers of this study. (authors)

  20. Underresolved absorption spectroscopy of OH radicals in flames using broadband UV LEDs

    Science.gov (United States)

    White, Logan; Gamba, Mirko

    2018-04-01

    A broadband absorption spectroscopy diagnostic based on underresolution of the spectral absorption lines is evaluated for the inference of species mole fraction and temperature in combustion systems from spectral fitting. The approach uses spectrally broadband UV light emitting diodes and leverages low resolution, small form factor spectrometers. Through this combination, the method can be used to develop high precision measurement sensors. The challenges of underresolved spectroscopy are explored and addressed using spectral derivative fitting, which is found to generate measurements with high precision and accuracy. The diagnostic is demonstrated with experimental measurements of gas temperature and OH mole fraction in atmospheric air/methane premixed laminar flat flames. Measurements exhibit high precision, good agreement with 1-D flame simulations, and high repeatability. A newly developed model of uncertainty in underresolved spectroscopy is applied to estimate two-dimensional confidence regions for the measurements. The results of the uncertainty analysis indicate that the errors in the outputs of the spectral fitting procedure are correlated. The implications of the correlation between uncertainties for measurement interpretation are discussed.

  1. Solar energy absorption characteristics and the effects of heat on the optical properties of several coatings

    Science.gov (United States)

    Lowery, J. R.

    1981-01-01

    The solar energy absorption characteristics of several high temperature coatings were determined and effects of heat on these coatings were evaluated. Included in the investigation were an electroplated alloy of black chrome and vanadium, electroplated black chrome, and chemically colored 316 stainless steel. Each of the coatings possessed good selective solar energy absorption properties at laboratory ambient temperature. Measured at a temperature of 700 K (800 F), the emittances of black chrome, black chrome vanadium, and colored stainless steel were 0.11, 0.61, and 0.15, respectively. Black chrome and black chrome vanadium did not degrade optically in the presence of high heat (811 K (1000 F)). Chemically colored stainless steel showed slight optical degradation when exposed to moderately high heat (616 K (650 F)0, but showed more severe degradation at exposure temperatures beyond this level. Each of the coatings showed good corrosion resistance to a salt spray environment.

  2. Techno-Economic Analysis of Solar Absorption Cooling for Commercial buildings in India

    Directory of Open Access Journals (Sweden)

    Muthalagappan Narayanan

    2017-11-01

    Full Text Available Space cooling and heating always tends to be a major part of the primary energy usage. By using fossil fuel electricity for these purposes, the situation becomes even worse. One of the major electricity consumptions in India is air conditioning. There are a lot of different technologies and few researchers have come up with a debate between solar absorption cooling and PV electric cooling. In a previous paper, PV electric cooling was studied and now as a continuation, this paper focuses on solar thermal absorption cooling systems and their application in commercial/office buildings in India. A typical Indian commercial building is taken for the simulation in TRNSYS. Through this simulation, the feasibility and operational strategy of the system is analysed, after which parametric study and economic analysis of the system is done. When compared with the expenses for a traditional air conditioner unit, this solar absorption cooling will take 13.6 years to pay back and will take 15.5 years to payback the price of itself and there after all the extra money are savings or profit.  Although the place chosen for this study is one of the typical tropical place in India, this payback might vary with different places, climate and the cooling demand. Article History: Received May 12th 2017; Received in revised form August 15th 2017; Accepted 1st Sept 2017; Available online How to Cite This Article: Narayanan, M. (2017. Techno-Economic Analysis of Solar Absorption Cooling for Commercial Buildings in India.  International Journal of Renewable Energy Development, 6(3, 253-262. https://doi.org/10.14710/ijred.6.3.253-262

  3. The role of aerosol absorption in driving clear-sky solar dimming over East Asia

    Science.gov (United States)

    Persad, Geeta G.; Ming, Yi; Ramaswamy, V.

    2014-09-01

    Surface-based observations indicate a significant decreasing trend in clear-sky downward surface solar radiation (SSR) over East Asia since the 1960s. This "dimming" is thought to be driven by the region's long-term increase in aerosol emissions, but little work has been done to quantify the underlying physical mechanisms or the contribution from aerosol absorption within the atmospheric column. Given the distinct climate impacts that absorption-driven dimming may produce, this constitutes an important, but thus far rather neglected, line of inquiry. We examine experiments conducted in the Geophysical Fluid Dynamics Laboratory's atmospheric general circulation models, AM2.1 and AM3, in order to analyze the model-simulated East Asian clear-sky SSR trends. We also use the models' stand-alone radiation module to examine the contribution from various aerosol characteristics in the two models (such as burden, mixing state, hygroscopicity, and seasonal distribution) to the trends. Both models produce trends in clear-sky SSR that are comparable to that observed but via disparate mechanisms. Despite their different aerosol characteristics, the models produce nearly identical increases in aerosol absorption since the 1960s, constituting as much as half of the modeled clear-sky dimming. This is due to a compensation between the differences in aerosol column burden and mixing state assumed in the two models, i.e., plausible clear-sky SSR simulations can be achieved via drastically different aerosol parameterizations. Our novel results indicate that trends in aerosol absorption drive a large portion of East Asian clear-sky solar dimming in the models presented here and for the time periods analyzed and that mechanistic analysis of the factors involved in aerosol absorption is an important diagnostic in evaluating modeled clear-sky solar dimming trends.

  4. Tunable Diode Laser Atomic Absorption Spectroscopy for Detection of Potassium under Optically Thick Conditions.

    Science.gov (United States)

    Qu, Zhechao; Steinvall, Erik; Ghorbani, Ramin; Schmidt, Florian M

    2016-04-05

    Potassium (K) is an important element related to ash and fine-particle formation in biomass combustion processes. In situ measurements of gaseous atomic potassium, K(g), using robust optical absorption techniques can provide valuable insight into the K chemistry. However, for typical parts per billion K(g) concentrations in biomass flames and reactor gases, the product of atomic line strength and absorption path length can give rise to such high absorbance that the sample becomes opaque around the transition line center. We present a tunable diode laser atomic absorption spectroscopy (TDLAAS) methodology that enables accurate, calibration-free species quantification even under optically thick conditions, given that Beer-Lambert's law is valid. Analyte concentration and collisional line shape broadening are simultaneously determined by a least-squares fit of simulated to measured absorption profiles. Method validation measurements of K(g) concentrations in saturated potassium hydroxide vapor in the temperature range 950-1200 K showed excellent agreement with equilibrium calculations, and a dynamic range from 40 pptv cm to 40 ppmv cm. The applicability of the compact TDLAAS sensor is demonstrated by real-time detection of K(g) concentrations close to biomass pellets during atmospheric combustion in a laboratory reactor.

  5. Cosmic radio-noise absorption bursts caused by solar wind shocks

    Directory of Open Access Journals (Sweden)

    A. Osepian

    2004-09-01

    Full Text Available Bursts of cosmic noise absorption observed at times of sudden commencements (SC of geomagnetic storms are examined. About 300SC events in absorption for the period 1967-1990 have been considered. It is found that the response of cosmic radio-noise absorption to the passage of an interplanetary shock depends on the level of the planetary magnetic activity preceding the SC event and on the magnitude of the magnetic field perturbation associated with the SC (as measured in the equatorial magnetosphere. It is shown that for SC events observed against a quiet background (Kp<2, the effects of the SC on absorption can be seen only if the magnitude of the geomagnetic field perturbation caused by the solar wind shock exceeds a threshold value ΔBth. It is further demonstrated that the existence of this threshold value, ΔBth, deduced from experimental data, can be related to the existence of a threshold for exciting and maintaining the whistler cyclotron instability, as predicted by quasi-linear theory. SC events observed against an active background (Kp<2 are accompanied by absorption bursts for all magnetic field perturbations, however small. A quantitative description of absorption bursts associated with SC events is provided by the whistler cyclotron instability theory.

  6. Identifying anthropogenic uranium compounds using soft X-ray near-edge absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ward, Jesse D.; Bowden, Mark; Tom Resch, C.; Eiden, Gregory C.; Pemmaraju, C. D.; Prendergast, David; Duffin, Andrew M.

    2017-01-01

    Uranium ores mined for industrial use are typically acid-leached to produce yellowcake and then converted into uranium halides for enrichment and purification. These anthropogenic chemical forms of uranium are distinct from their mineral counterparts. The purpose of this study is to use soft X-ray absorption spectroscopy to characterize several common anthropogenic uranium compounds important to the nuclear fuel cycle. Non-destructive chemical analyses of these compounds is important for process and environmental monitoring and X-ray absorption techniques have several advantages in this regard, including element-specificity, chemical sensitivity, and high spectral resolution. Oxygen K-edge spectra were collected for uranyl nitrate, uranyl fluoride, and uranyl chloride, and fluorine K-edge spectra were collected for uranyl fluoride and uranium tetrafluoride. Interpretation of the data is aided by comparisons to calculated spectra. These compounds have unique spectral signatures that can be used to identify unknown samples.

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

    Science.gov (United States)

    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.

  8. Measurement of He neutral temperature in detached plasmas using laser absorption spectroscopy

    Science.gov (United States)

    Aramaki, M.; Tsujihara, T.; Kajita, S.; Tanaka, H.; Ohno, N.

    2018-01-01

    The reduction of the heat load onto plasma-facing components by plasma detachment is an inevitable scheme in future nuclear fusion reactors. Since the control of the plasma and neutral temperatures is a key issue to the detached plasma generation, we have developed a laser absorption spectroscopy system for the metastable helium temperature measurements and used together with a previously developed laser Thomson scattering system for the electron temperature and density measurements. The thermal relaxation process between the neutral and the electron in the detached plasma generated in the linear plasma device, NAGDIS-II was studied. It is shown that the electron temperature gets close to the neutral temperature by increasing the electron density. On the other hand, the pressure dependence of electron and neutral temperatures shows the cooling effect by the neutrals. The possibility of the plasma fluctuation measurement using the fluctuation in the absorption signal is also shown.

  9. Empirical model description of photon path length for differential path length spectroscopy: combined effect of scattering and absorption

    NARCIS (Netherlands)

    Kanick, Stephen C.; Sterenborg, Henricus J. C. M.; Amelink, Arjen

    2008-01-01

    Differential path length spectroscopy (DPS) is a method of reflectance spectroscopy that utilizes a specialized fiber geometry to make the photon path length (tau) insensitive to variations in tissue optical properties over a wide range of absorption (mu(a)) and total scattering (mu(s))

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

    Energy Technology Data Exchange (ETDEWEB)

    Oraiqat, I; Rehemtulla, A; Lam, K; Ten Haken, R; El Naqa, I [University of Michigan, Radiation Oncology, Ann Arbor, MI (United States); Clarke, R [University of Michigan, Physics Department, Ann Arbor, MI (United States)

    2016-06-15

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

  11. Platinum assay by neutron activation analysis and atomic absorption spectroscopy in cisplatin treated pregnant mice

    International Nuclear Information System (INIS)

    Esposito, M.; Collecchi, P.; Oddone, M.; Meloni, S.

    1987-01-01

    Cisplatin (CDDP) is an antineoplastic drug used in the treatment of a wide variety of tumors. This paper describes an investigation carried out on pregnant mice after intragastric or intraperitoneal treatment with CDDP from the 11st to 13rd day of gestation. Platinum content in different liver, kidney, placenta and brain tissues, was determined at 18. day of pregnancy. Neutron activation analysis and atomic absorption spectroscopy were used. Results of both techniques are presented and discussed in terms of precision, accuracy and sensitivity. Neutron activation analysis appears to provide better results correlated with the drug treatment. (author) 10 refs.; 4 tables

  12. Detection of nitric oxide in exhaled air using cavity enhanced absorption spectroscopy

    Science.gov (United States)

    Medrzycki, R.; Wojtas, J.; Rutecka, B.; Bielecki, Z.

    2013-07-01

    The article describes an application one of the most sensitive optoelectronic method - Cavity Enhanced Absorption Spectroscopy in investigation of nitric oxide in exhaled breath. Measurement of nitric oxide concentration in exhaled breath is a quantitative, non-invasive, simple, and safe method of respiratory inflammation and asthma diagnosis. For detection of nitric oxide by developed optoelectronic sensor the vibronic molecular transitions were used. The wavelength ranges of these transitions are situated in the infrared spectral region. A setup consists of the optoelectronic nitric oxide sensor integrated with sampling and sample conditioning unit. The constructed detection system provides to measure nitric oxide in a sample of 0-97% relative humidity.

  13. [Gas pipeline leak detection based on tunable diode laser absorption spectroscopy].

    Science.gov (United States)

    Zhang, Qi-Xing; Wang, Jin-Jun; Liu, Bing-Hai; Cai, Ting-Li; Qiao, Li-Feng; Zhang, Yong-Ming

    2009-08-01

    The principle of tunable diode laser absorption spectroscopy and harmonic detection technique was introduced. An experimental device was developed by point sampling through small multi-reflection gas cell. A specific line near 1 653. 7 nm was targeted for methane measurement using a distributed feedback diode laser as tunable light source. The linearity between the intensity of second harmonic signal and the concentration of methane was determined. The background content of methane in air was measured. The results show that gas sensors using tunable diode lasers provide a high sensitivity and high selectivity method for city gas pipeline leak detection.

  14. Wavelength modulation spectroscopy--digital detection of gas absorption harmonics based on Fourier analysis.

    Science.gov (United States)

    Mei, Liang; Svanberg, Sune

    2015-03-20

    This work presents a detailed study of the theoretical aspects of the Fourier analysis method, which has been utilized for gas absorption harmonic detection in wavelength modulation spectroscopy (WMS). The lock-in detection of the harmonic signal is accomplished by studying the phase term of the inverse Fourier transform of the Fourier spectrum that corresponds to the harmonic signal. The mathematics and the corresponding simulation results are given for each procedure when applying the Fourier analysis method. The present work provides a detailed view of the WMS technique when applying the Fourier analysis method.

  15. The determination of aluminum, copper, iron, and lead in glycol formulations by atomic absorption spectroscopy

    Science.gov (United States)

    1977-01-01

    Initial screening tests and the results obtained in developing procedures to determine Al, Cu, Fe, and Pb in glycol formulations are described. Atomic absorption completion was selected for Cu, Fe and Pb, and after comparison with emission spectroscopy, was selected for Al also. Before completion, carbon, iron, and lead are extracted with diethyl dithio carbamate (DDC) into methyl isobutyl ketone (MIBK). Aluminum was also extracted into MIBK using 8-hydroxyquinoline as a chelating agent. As little as 0.02 mg/l carbon and 0.06 mg/l lead or iron may be determined in glycol formulations. As little as 0.3 mg/l aluminum may be determined.

  16. Determination of heavy metals in solid emission and immission samples using atomic absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Fara, M.; Novak, F. [EGU Prague, PLC, Bichovice, Prague (Czechoslovakia)

    1995-12-01

    Both flame and electrothermal methods of atomic absorption spectroscopy (AAS) have been applied to the determination of Al, As, Be, Ca, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, TI, Se, V and Zn in emission and emission (deposition) samples decomposed in open PTFE test-tubes by individual fuming-off hydrofluoric, perchloroic and nitric acid. An alternative hydride technique was also used for As and Se determination and Hg was determined using a self-contained AAS analyzer. A graphite platform proved good to overcome non-spectral interferences in AAS-ETA. Methods developed were verified by reference materials (inc. NBS 1633a).

  17. Strontium Localization in Bone Tissue Studied by X-Ray Absorption Spectroscopy

    DEFF Research Database (Denmark)

    Frankær, Christian Grundahl; Raffalt, Anders Christer; Ståhl, Kenny

    2014-01-01

    Strontium has recently been introduced as a pharmacological agent for the treatment and prevention of osteoporosis. We determined the localization of strontium incorporated into bone matrix from dogs treated with Sr malonate by X-ray absorption spectroscopy. A new approach for analyzing the X...... highly ordered sites, and at least 30 % is located at less ordered sites where only the first solvation shell is resolved, suggesting that strontium is sur- rounded by only oxygen atoms similar to Sr2? in solution. Strontium was furthermore shown to be absorbed in collagen in which it obtains a higher...

  18. Absolute frequency atlas from 915 nm to 985 nm based on laser absorption spectroscopy of iodine

    Science.gov (United States)

    Nölleke, Christian; Raab, Christoph; Neuhaus, Rudolf; Falke, Stephan

    2018-04-01

    This article reports on laser absorption spectroscopy of iodine gas between 915 nm and 985 nm. This wavelength range is scanned utilizing a narrow linewidth and mode-hop-free tunable diode-laser whose frequency is actively controlled using a calibrated wavelength meter. This allows us to provide an iodine atlas that contains almost 10,000 experimentally observed reference lines with an uncertainty of 50 MHz. For common lines, good agreement is found with a publication by Gerstenkorn and Luc (1978). The new rich dataset allows existing models of the iodine molecule to be refined and can serve as a reference for laser frequency calibration and stabilization.

  19. Microscale X-ray Absorption Spectroscopy on the GSECARS Sector 13 at the APS

    CERN Document Server

    Stephen-Sutto

    2000-01-01

    GeoSoilEnviroCARS (GSECARS) is a national user facility for frontier research in the earth sciences using synchrotrons radiation at the Advanced Photon Source, Argonne National Laboratory. GSECARS provides earth scientists with access to the high-brilliance hard x-rays from this third-generation synchrotrons light source. The research conducted at this facility will advance our knowledge of the composition, structure and properties of earth materials, the processes they control and the processes that produce them. All principal synchrotron-based analytical techniques in demand by earth scientists are being brought to bear on earth science problems: (1) high-pressure/high-temperature crystallography and spectroscopy using the diamond anvil cell; (2) high-pressure/high-temperature crystallography using the large-volume press; (3) powder, single crystal and interface diffraction; (4) x-ray absorption fine structure (XAFS) spectroscopy; (5) x-ray fluorescence microprobe analysis and microspectroscopy; and (6) mic...

  20. Study of cancer cell lines with Fourier transform infrared (FTIR)/vibrational absorption (VA) spectroscopy

    DEFF Research Database (Denmark)

    Uceda Otero, E. P.; Eliel, G. S. N.; Fonseca, E. J. S.

    2013-01-01

    In this work we have used Fourier transform infrared (FTIR) / vibrational absorption (VA) spectroscopy to study two cancer cell lines: the Henrietta Lacks (HeLa) human cervix carcinoma and 5637 human bladder carcinoma cell lines. Our goal is to experimentally investigate biochemical changes...... and differences in these cells lines utilizing FTIR spectroscopy. We have used the chemometrical and statistical method principal component analysis (PCA) to investigate the spectral differences. We have been able to identify certain bands in the spectra which are so-called biomarkers for two types of cell lines......, three groups for the 5637 human bladder carcinoma cell line (5637A, 5637B and 5637C), and another one for the HeLa human cervix carcinoma cell line. The vibrational modes can be assigned to specific bands involving characteristic motions of the protein backbone. This work shows that infrared vibrational...

  1. Effect of solar irradiation on forced convective heat transfer through a nanofluid based direct absorption solar collector

    Science.gov (United States)

    Parvin, Salma; Ahmed, Sajid; Chowdhury, Raju

    2017-06-01

    The present work investigates numerically the convective and radiative heat transfer performance and entropy generation of forced convection through a direct absorption solar collector (DASC). Four different fluids; Cu-water nanofluid, Al2O3-waternanofluid, TiO2-water nanofluid and pure water are used as the working fluid. Entropy production has been taken into account in addition to the collector efficiency and heat transfer enhancement. Penalty finite element method with Galerkin's weighted residual technique is used to solve the governing non-linear partial differential equations. Numerical simulations are performed for the variation of solar irradiation (I). The outcomes are presented in the form of isotherms, average output temperature, the average Nusselt number, collector efficiency, average entropy generation and Bejan number. The results present that the rate of heat transfer and collector efficiency enhance significantly for raising the values of I upto a certain range.

  2. Dual interface gratings design for absorption enhancement in thin crystalline silicon solar cells

    Science.gov (United States)

    Zhang, Jinqiannan; Yu, Zhongyuan; Liu, Yumin; Chai, Hongyu; Hao, Jing; Ye, Han

    2017-09-01

    We numerically study and analyze the light absorption enhancement in thin crystalline silicon solar cell with dual interface gratings. The structure combines the front dielectric nanowalls and the sinusoidal plasmonic grating at back reflector. We show that having specific interfaces with well-chosen period, fill factor and height can allow more efficient dielectric and plasmonic modes coupling into active layer and can improve the solar cell performance. For 1 μm active layer case, the optimal result for the proposed structure achieves short-circuit current of 23.6 mA/cm2, which performs over 50% better than flat solar cell structure, the short-circuit current of which is 15.5 mA/cm2. In addition, the active layer thickness and angular analysis show that the proposed structure maintains its advantage over flat structure.

  3. Giant quiescent solar filament observed with high-resolution spectroscopy

    Science.gov (United States)

    Kuckein, C.; Verma, M.; Denker, C.

    2016-05-01

    Aims: An extremely large filament was studied in various layers of the solar atmosphere. The inferred physical parameters and the morphological aspects are compared with smaller quiescent filaments. Methods: A giant quiet-Sun filament was observed with the high-resolution Echelle spectrograph at the Vacuum Tower Telescope at Observatorio del Teide, Tenerife, Spain, on 2011 November 15. A mosaic of spectra (ten maps of 100″ × 182″) was recorded simultaneously in the chromospheric absorption lines Hα and Na I D2. Physical parameters of the filament plasma were derived using cloud model (CM) inversions and line core fits. The spectra were complemented with full-disk filtergrams (He I λ10830 Å, Hα, and Ca II K) of the Chromospheric Telescope (ChroTel) and full-disk magnetograms of the Helioseismic and Magnetic Imager (HMI). Results: The filament had extremely large linear dimensions (~817 arcsec), which corresponds to about 658 Mm along a great circle on the solar surface. A total amount of 175119 Hα contrast profiles were inverted using the CM approach. The inferred mean line-of-sight (LOS) velocity, Doppler width, and source function were similar to previous works of smaller quiescent filaments. However, the derived optical thickness was higher. LOS velocity trends inferred from the Hα line core fits were in accord but weaker than those obtained with CM inversions. Signatures of counter-streaming flows were detected in the filament. The largest brightening conglomerates in the line core of Na I D2 coincided well with small-scale magnetic fields as seen by HMI. Mixed magnetic polarities were detected close to the ends of barbs. The computation of photospheric horizontal flows based on HMI magnetograms revealed flow kernels with a size of 5-8 Mm and velocities of 0.30-0.45 km s-1 at the ends of the filament. Conclusions: The physical properties of extremely large filaments are similar to their smaller counterparts, except for the optical thickness, which in

  4. SO2 EMISSION MEASUREMENT BY DOAS (DIFFERENTIAL OPTICAL ABSORPTION SPECTROSCOPY AND COSPEC (CORRELATION SPECTROSCOPY AT MERAPI VOLCANO (INDONESIA

    Directory of Open Access Journals (Sweden)

    Hanik Humaida

    2010-06-01

    Full Text Available The SO2 is one of the volcanic gases that can use as indicator of volcano activity. Commonly, SO2 emission is measured by COSPEC (Correlation Spectroscopy. This equipment has several disadvantages; such as heavy, big in size, difficulty in finding spare part, and expensive. DOAS (Differential Optical Absorption Spectroscopy is a new method for SO2 emission measurement that has advantages compares to the COSPEC. Recently, this method has been developed. The SO2 gas emission measurement of Gunung Merapi by DOAS has been carried out at Kaliadem, and also by COSPEC method as comparation. The differences of the measurement result of both methods are not significant. However, the differences of minimum and maximum result of DOAS method are smaller than that of the COSPEC. It has range between 51 ton/day and 87 ton/day for DOAS and 87 ton/day and 201 ton/day for COSPEC. The measurement of SO2 gas emission evaluated with the seismicity data especially the rockfall showed the presence of the positive correlation. It may cause the gas pressure in the subsurface influencing instability of 2006 eruption lava.   Keywords: SO2 gas, Merapi, DOAS, COSPEC

  5. Structure and property investigations of TDO in aqueous phase by density functional theory, UV absorption, and Raman spectroscopy.

    Science.gov (United States)

    Shao, Jianzhong; Liu, Xiaoyun; Chen, Pin; Wu, Qiuxia; Zheng, Xuming; Pei, Kemei

    2014-05-01

    Density functional theory, UV absorption, and Raman spectroscopy are used to investigate the structure and properties of TDO in aqueous solution. The equilibrium structures, UV absorption spectra, interaction energies, and Raman spectroscopy data of TDO, AIMSA, and 12 TDO or AIMSA clusters are calculated. Raman spectroscopy experiments are carried out by 488 and 208 nm laser excitation. The Raman spectra of TDO in solid and aqueous phases have been compared, and the most possible structure for TDO in aqueous phase was deduced from analysis of the DFT calculations for the examined models, the experimental UV absorption spectrum, and Raman spectra of TDO. The interaction energy results show that TDO's solubility in water is originated from the TDO-water cyclic oligomer. The calculated UV absorption and Raman spectra of the I2·2H2O-cyc cluster model agree with the experimental results of TDO in aqueous solution very well.

  6. Microcrystalline silicon films and solar cells investigatet by photoluminescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Merdzhanova, T.

    2005-07-01

    A systematic investigation on photoluminescence (PL) properties of microcrystalline silicon ({mu}c-Si:H) films with structural composition changing from highly crystalline to predominantly amorphous is presented. The samples were prepared by PECVD and HWCVD with different silane concentration in hydrogen (SC). By using photoluminescence in combination with Raman spectroscopy the relationship between electronic properties and the microstructure of the material is studied. The PL spectra of {mu}c-Si:H reveal a rather broad ({proportional_to}0.13 eV) featureless band at about 1 eV ('{mu}c'-Si-band). In mixed phase material of crystalline and amorphous regions, a band at about 1.3 eV with halfwidth of about 0.3 eV is found in addition to '{mu}c'-Si-band, which is attributed to the amorphous phase ('a'-Si-band). Similarly to amorphous silicon, the '{mu}c'-Si-band is assigned to recombination between electrons and holes in band tail states. An additional PL band centred at about 0.7 eV with halfwidth slightly broader than the '{mu}c'-Si-band is observed only for films prepared at high substrate temperature and it is preliminarily assigned to defect-related transitions as in polycrystalline silicon. With decreasing crystalline volume fraction, the '{mu}c'-Si-band shifts continuously to higher energies for all {mu}c-Si:H films but the linewidth of the PL spectra is almost unaffected. This is valid for all deposition conditions investigated. The results are interpreted, assuming decrease of the density of band tail states with decreasing crystalline volume fraction. A simple model is proposed to simulate PL spectra and V{sub oc} in {mu}c-Si:H solar cells as a function of temperature, based on carrier distributions in quasi-equilibrium conditions. In the model is assumed symmetric density of states distributions for electrons and holes in the conduction and the valence band tail states. The best agreement between

  7. Design of solar cell materials via soft X-ray spectroscopy

    DEFF Research Database (Denmark)

    Himpsel, F.J.; Cook, P.L.; de la Torre, G.

    2013-01-01

    . There are four relevant energy levels that can be measured with a combination of X-ray absorption spectroscopy and photoelectron spectroscopy, as illustrated for an organic dye as absorber attached to a p-doped diamond film as donor. Systematic measurements of organometallic dyes (phthalocyanines and porphyrins...

  8. Atmospheric extinction in solar tower plants: absorption and broadband correction for MOR measurements

    Science.gov (United States)

    Hanrieder, N.; Wilbert, S.; Pitz-Paal, R.; Emde, C.; Gasteiger, J.; Mayer, B.; Polo, J.

    2015-08-01

    Losses of reflected Direct Normal Irradiance due to atmospheric extinction in concentrated solar tower plants can vary significantly with site and time. The losses of the direct normal irradiance between the heliostat field and receiver in a solar tower plant are mainly caused by atmospheric scattering and absorption by aerosol and water vapor concentration in the atmospheric boundary layer. Due to a high aerosol particle number, radiation losses can be significantly larger in desert environments compared to the standard atmospheric conditions which are usually considered in ray-tracing or plant optimization tools. Information about on-site atmospheric extinction is only rarely available. To measure these radiation losses, two different commercially available instruments were tested, and more than 19 months of measurements were collected and compared at the Plataforma Solar de Almería. Both instruments are primarily used to determine the meteorological optical range (MOR). The Vaisala FS11 scatterometer is based on a monochromatic near-infrared light source emission and measures the strength of scattering processes in a small air volume mainly caused by aerosol particles. The Optec LPV4 long-path visibility transmissometer determines the monochromatic attenuation between a light-emitting diode (LED) light source at 532 nm and a receiver and therefore also accounts for absorption processes. As the broadband solar attenuation is of interest for solar resource assessment for concentrated solar power (CSP), a correction procedure for these two instruments is developed and tested. This procedure includes a spectral correction of both instruments from monochromatic to broadband attenuation. That means the attenuation is corrected for the time-dependent solar spectrum which is reflected by the collector. Further, an absorption correction for the Vaisala FS11 scatterometer is implemented. To optimize the absorption and broadband correction (ABC) procedure, additional

  9. Atmospheric extinction in solar tower plants: absorption and broadband correction for MOR measurements

    Directory of Open Access Journals (Sweden)

    N. Hanrieder

    2015-08-01

    Full Text Available Losses of reflected Direct Normal Irradiance due to atmospheric extinction in concentrated solar tower plants can vary significantly with site and time. The losses of the direct normal irradiance between the heliostat field and receiver in a solar tower plant are mainly caused by atmospheric scattering and absorption by aerosol and water vapor concentration in the atmospheric boundary layer. Due to a high aerosol particle number, radiation losses can be significantly larger in desert environments compared to the standard atmospheric conditions which are usually considered in ray-tracing or plant optimization tools. Information about on-site atmospheric extinction is only rarely available. To measure these radiation losses, two different commercially available instruments were tested, and more than 19 months of measurements were collected and compared at the Plataforma Solar de Almería. Both instruments are primarily used to determine the meteorological optical range (MOR. The Vaisala FS11 scatterometer is based on a monochromatic near-infrared light source emission and measures the strength of scattering processes in a small air volume mainly caused by aerosol particles. The Optec LPV4 long-path visibility transmissometer determines the monochromatic attenuation between a light-emitting diode (LED light source at 532 nm and a receiver and therefore also accounts for absorption processes. As the broadband solar attenuation is of interest for solar resource assessment for concentrated solar power (CSP, a correction procedure for these two instruments is developed and tested. This procedure includes a spectral correction of both instruments from monochromatic to broadband attenuation. That means the attenuation is corrected for the time-dependent solar spectrum which is reflected by the collector. Further, an absorption correction for the Vaisala FS11 scatterometer is implemented. To optimize the absorption and broadband correction (ABC procedure

  10. Fusion of Ultraviolet-Visible and Infrared Transient Absorption Spectroscopy Data to Model Ultrafast Photoisomerization.

    Science.gov (United States)

    Debus, Bruno; Orio, Maylis; Rehault, Julien; Burdzinski, Gotard; Ruckebusch, Cyril; Sliwa, Michel

    2017-08-03

    Ultrafast photoisomerization reactions generally start at a higher excited state with excess of internal vibrational energy and occur via conical intersections. This leads to ultrafast dynamics which are difficult to investigate with a single transient absorption spectroscopy technique, be it in the ultraviolet-visible (UV-vis) or infrared (IR) domain. On one hand, the information available in the UV-vis domain is limited as only slight spectral changes are observed for different isomers. On the other hand, the interpretation of vibrational spectra is strongly hindered by intramolecular relaxation and vibrational cooling. These limitations can be circumvented by fusing UV-vis and IR transient absorption spectroscopy data in a multiset multivariate curve resolution analysis. We apply this approach to describe the spectrodynamics of the ultrafast cis-trans photoisomerization around the C-N double bond observed for aromatic Schiff bases. Twisted intermediate states could be elucidated, and isomerization was shown to occur through a continuous complete rotation. More broadly, data fusion can be used to rationalize a vast range of ultrafast photoisomerization processes of interest in photochemistry.

  11. The use of absorption spectroscopy of plutonium to minimize waste streams

    International Nuclear Information System (INIS)

    Vaughn, R.B.; Berg, J.; Cisneros, M.

    1997-01-01

    Through the use of absorption spectroscopy we are better able to understand the chemical reactions of plutonium and other actinide elements in solution. In many cases such an understanding can minimize the generation of waste streams by suggesting more optimal chemical conditions for separating these radioactive elements from their host matrix. Many processes are developed using an empirical approach with little understanding of what is actually taking place. One such example is the anion exchange process for Plutonium purification. Various resins have been tested in various solutions and workable outcomes have been produced. However, absorption spectroscopy provides an understanding of why ion exchange works and can determine which compounds complex best with actinides in order to obtain a more efficient and effective separations process. This presentation will touch on the chemistry involved, the spectroscopic instrumentation, and the environmental impacts. Primarily the talk will focus on the chemical technicians involvement in the day to day research, the obstacles encountered, and the environment in which this research was conducted

  12. A method of reducing background fluctuation in tunable diode laser absorption spectroscopy

    Science.gov (United States)

    Yang, Rendi; Dong, Xiaozhou; Bi, Yunfeng; Lv, Tieliang

    2018-03-01

    Optical interference fringe is the main factor that leads to background fluctuation in gas concentration detection based on tunable diode laser absorption spectroscopy. The interference fringes are generated by multiple reflections or scatterings upon optical surfaces in optical path and make the background signal present an approximated sinusoidal oscillation. To reduce the fluctuation of the background, a method that combines dual tone modulation (DTM) with vibration reflector (VR) is proposed in this paper. The combination of DTM and VR can make the unwanted periodic interference fringes to be averaged out and the effectiveness of the method in reducing background fluctuation has been verified by simulation and real experiments in this paper. In the detection system based on the proposed method, the standard deviation (STD) value of the background signal is decreased to 0.0924 parts per million (ppm), which is reduced by a factor of 16 compared with that of wavelength modulation spectroscopy. The STD value of 0.0924 ppm corresponds to the absorption of 4 . 328 × 10-6Hz - 1 / 2 (with effective optical path length of 4 m and integral time of 0.1 s). Moreover, the proposed method presents a better stable performance in reducing background fluctuation in long time experiments.

  13. Redox Behavior of Fe2+/Fe3+ Redox Couple by Absorption Spectroscopy and Measurement

    International Nuclear Information System (INIS)

    Oh, J. Y.; Park, S.; Yun, J. I.

    2010-01-01

    Redox behavior has influences on speciation and other geochemical reactions of radionuclides such as sorption, solubility, and colloid formation, etc. It is one of the factors for evaluation of long-term safety assessment under high-level radioactive waste (HLW) disposal conditions. Accordingly, redox potential (Eh) measurement in aquatic system is important to investigate the redox conditions. Eh is usually measured with redox active electrodes (Pt, Au, glassy carbon, etc.). Nevertheless, Eh measurements by general methods using electrodes provide low accuracy and high uncertainty problem. Therefore, Eh calculated from the concentration of redox active elements with a proper complexing reagent by using UV-Vis absorption spectroscopy is progressed. Iron exists mostly as spent nuclear waste container material and in hydro-geologic minerals. In this system, iron controls the redox condition in near-field area and influences chemical behavior and speciation of radionuclides including redox sensitive actinides such as U, Np, and Pu. In the present work, we present the investigation on redox phenomena of iron in aquatic system by a combination of absorption spectroscopy and redox potential measurements

  14. X-ray absorption spectroscopy investigation of structurally modified lithium niobate crystals

    Energy Technology Data Exchange (ETDEWEB)

    Vitova, Tonya

    2008-02-15

    The type and concentration of impurity centers in different valence states are crucial for tuning the photorefractive properties of doped Lithium Niobate (LN) crystals. X-ray Absorption Spectroscopy (XAS) is an appropriate tool for studying the local structure of impurity centers. XAS combined with absorption in UV/VIS/IR and High Resolution X-ray Emission Spectroscopy (HRXES) provide information about the valence state of the dopant ions in as-grown, reduced or oxidized doped LN crystals. Cu (Cu{sup 1+} and Cu{sup 2+}) and Fe (Fe{sup 2+} and Fe{sup 3+}) atoms are found in two different valence states, whereas there are indications for a third Mn valency, in addition to Mn{sup 2+} and Mn{sup 3+} in manganese-doped LN crystals. One of the charge compensation mechanisms during reduction of copper- doped LN crystals is outgassing of oxygen atoms. Cu ions in the reduced crystals have at least two different site symmetries: twofold (Cu{sup 1+}) and sixfold (Cu{sup 2+}) coordinated by O atoms. Fe and Mn atoms are coordinated by six O atoms. Cu and Fe ions are found to occupy only Li sites, whereas Mn ions are also incorporated into Li and Nb sites. The refractive index change in LN crystals irradiated with {sup 3}He{sup 2+} ions is caused by structurally disordered centers, where Nb atoms are displaced from normal crystallographic sites and Li or/and O vacancies are present. (orig.)

  15. Combined characterization of bovine polyhemoglobin microcapsules by UV-Vis absorption spectroscopy and cyclic voltammetry.

    Science.gov (United States)

    Knirsch, Marcos Camargo; Dell'Anno, Filippo; Salerno, Marco; Larosa, Claudio; Polakiewicz, Bronislaw; Eggenhöffner, Roberto; Converti, Attilio

    2017-03-01

    Polyhemoglobin produced from pure bovine hemoglobin by reaction with PEG bis(N-succynimidil succinate) as a cross-linking agent was encapsulated in gelatin and dehydrated by freeze-drying. Free carboxyhemoglobin and polyhemoglobin microcapsules were characterized by UV-Vis spectroscopy in the absorption range 450-650 nm and cyclic voltammetry in the voltage range from -0.8 to 0.6 mV to evaluate the ability to break the bond with carbon monoxide and to study the carrier's affinity for oxygen, respectively. SEM used to observe the shape of cross-linked gelatin-polyhemoglobin microparticles showed a regular distribution of globular shapes, with mean size of ~750 nm, which was ascribed to gelatin. Atomic absorption spectroscopy was also performed to detect iron presence in microparticles. Cyclic voltammetry using an Ag-AgCl electrode highlighted characteristic peaks at around -0.6 mV that were attributed to reversible oxygen bonding with iron in oxy-polyhemoglobin structure. These results suggest this technique as a powerful, direct and alternative method to evaluate the extent of hemoglobin oxygenation.

  16. Improved Sensitivity of Spectroscopic Quantification of Stable Isotope Content Using Capillary Absorption Spectroscopy

    Science.gov (United States)

    Moran, J.; Wilcox Freeburg, E.; Kriesel, J.; Linley, T. J.; Kelly, J.; Coleman, M. L.; Christensen, L. E.; Vance, S.

    2016-12-01

    Spectroscopy-based platforms have recently risen to the forefront for making stable isotope measurements of methane, carbon dioxide, water, or other analytes. These spectroscopy systems can be relatively straightforward to operate (versus a mass spectrometry platform), largely relieve the analyst of mass interference artifacts, and many can be used in the field. Despite these significant advantages, however, existing spectroscopy techniques suffer from a lack of measurement sensitivity that can ultimately limit select applications including spatially resolved and compound-specific measurements. Here we present a capillary absorption spectroscopy (CAS) system that is designed to mitigate sensitivity issues in spectroscopy-based stable isotope evaluation. The system uses mid-wave infrared excitation generated from a continuous wave quantum cascade laser. Importantly, the sample `chamber' is a flexible capillary with a total volume of less than one cc. Proprietary coatings on the internal surface of the fiber improve optical performance, guiding the light to a detector and facilitating high levels of interaction between the laser beam and gaseous analytes. We present data demonstrating that a tapered hollow fiber cell, with an internal diameter that broadens toward the detector, reduces optical feedback to further improve measurement sensitivity. Sensitivity of current hollow fiber / CAS systems enable measurements of only 10's of picomoles CO2 while theoretical improvements should enable measurements of as little as 10's of femtomoles. Continued optimization of sample introduction and improvements to optical feedback are being explored. Software is being designed to provide rapid integration of data and generation of processed isotope measurements using a graphical user interface. Taken together, the sensitivity improvements of the CAS system under development could, when coupled to a laser ablation sampling device, enable up to 2 µm spatial resolution (roughly the

  17. Stratospheric and mesospheric pressure-temperature profiles from rotational analysis of CO2 lines in atmospheric trace molecule spectroscopy/ATLAS 1 infrared solar occultation spectra

    Science.gov (United States)

    Stiller, G. P.; Gunson, M. R.; Lowes, L. L.; Abrams, M. C.; Raper, O. F.; Farmer, C. B.; Zander, R.; Rinsland, C. P.

    1995-01-01

    A simple, classical, and expedient method for the retrieval of atmospheric pressure-temperature profiles has been applied to the high-resolution infrared solar absorption spectra obtained with the atmospheric trace molecule spectroscopy (ATMOS) instrument. The basis for this method is a rotational analysis of retrieved apparent abundances from CO2 rovibrational absorption lines, employing existing constituent concentration retrieval software used in the analysis of data returned by ATMOS. Pressure-temperature profiles derived from spectra acquired during the ATLAS 1 space shuttle mission of March-April 1992 are quantitatively evaluated and compared with climatological and meteorological data as a means of assessing the validity of this approach.

  18. Planetary gamma-ray spectroscopy: the effects of hydrogen absorption cross-section of the gamma-ray spectrum

    International Nuclear Information System (INIS)

    Lapides, J.R.

    1981-01-01

    The gamma-ray spectroscopy of planet surfaces is one of several possible methods that are useful in determining the elemental composition of planet surfaces from orbiting spacecraft. This has been demonstrated on the Apollos 15 and 16 missions as well as the Soviet Mars-5 mission. Planetary gamma-ray emission is primarily the result of natural radioactive decay and cosmic-ray and solar-flare-induced nuclear reactions. Secondary neutron reactions play a large role in the more intense gamma-ray emission. The technique provides information on the elemental composition of the top few tens of centimeters of the planet surface. Varying concentrations of hydrogen and compositional variations that alter the macroscopic thermal-neutron absorption cross section have a significant effect on the neutron flux in the planet surface and therefore also on the gamma-ray emission from the surface. These effects have been systematically studied for a wide range of possible planetary compositions that include Mercury, the moon, Mars, the comets, and the asteroids. The problem of the Martian atmosphere was also investigated. The results of these calculations, in which both surface neutron fluxes and gamma-ray emission fluxes were determined, were used to develop general procedures for obtaining planet compositions from the gamma-ray spectrum. Several changes have been suggested for reanalyzing the Apollos 15 and 16 gamma-ray results. In addition, procedures have been suggested that can be applied to neutron-gamma techniques in mineral and oil exploration

  19. Total Absorption Spectroscopy Study of the Beta Decay of 60Mn to Constrain the Neutron Capture Rate of 60Fe

    Science.gov (United States)

    Richman, Debra; Spyrou, Artemis; Dombos, Alex; Couture, Aaron; e15034 Collaboration

    2017-09-01

    Interest in 60Fe, a long lived radioisotope synthesized in massive stars, has recently peaked. The signature of its decay allows us to probe astrophysical processes, events such as the early formation of the solar system and nucleosynthesis. To understand these observations a complete understanding of the creation, destruction and nuclear properties of 60Fe in the astrophysical environment are required. Using the beta decay of 60Mn in conjunction with total absorption spectroscopy (TAS), made possible by the high efficiency gamma ray calorimeter SuN (Summing NaI detector) at the National Superconducting Cyclotron Laboratory (NSCL), to study the distribution of beta-decay intensity over the daughter-nucleus 60Fe, provides information about the structure of the daughter and improves the predictive power of astrophysical models. In addition to the ongoing TAS analysis, The Beta-Oslo method will be used to extract the nuclear level density and gamma-strength function of 60Fe providing much needed constraints on the neutron capture reaction rate responsible for the creation of this nucleus.

  20. Exhaust gas monitoring based on absorption spectroscopy in the process industry

    Science.gov (United States)

    Zhang, Shuai; Liu, Wen-qing; Zhang, Yu-jun; Shu, Xiao-wen; Kan, Rui-feng; Cui, Yi-ben; He, Ying; Xu, Zhen-yu; Geng, Hui; Liu, Jian-guo

    2009-07-01

    This non-invasive gas monitor for exhaust gas monitoring must has high reliability and requires little maintenance. Monitor for in-situ measurements using tunable diode laser absorption spectroscopy (TDLAS) in the near infrared, can meet these requirements. TDLAS has evolved over the past decade from a laboratory especially to an accepted, robust and reliable technology for trace gas sensing. With the features of tunability and narrow linewidth of the distributed feedback (DFB) diode laser and by precisely tuning the laser output wavelength to a single isolated absorption line of the gas, TDLAS technique can be utilized to measure gas concentration with high sensitivity. Typical applications for monitoring of H2S, NH3, HC1 and HF are described here together by wavelength modulation spectroscopy with second-harmonic(WMS-2F) detection. This paper will illustrate the problems related to on-line applications, in particular, the overfall effects, automatic light intensity correction, temperature correction, which impacted on absorption coefficient and give details of how effect of automatic correction is necessary. The system mainly includes optics and electronics, optical system mainly composed of fiber, fiber coupler and beam expander, the electron part has been placed in safe analysis room not together with the optical part. Laser merely passes through one-meter-long pipes by the fiber coupling technology, so the system itself has anti-explosion. The results of the system are also presented in the end, the system's response time is only 0.5s, and can be achieved below 1×10-5 the detection limit at the volume fraction, it can entirely replace the traditional methods of detection exhaust gas in the process industry.

  1. Initial Results of Optical Vortex Laser Absorption Spectroscopy in the HYPER-I Device

    Science.gov (United States)

    Yoshimura, Shinji; Asai, Shoma; Aramaki, Mitsutoshi; Terasaka, Kenichiro; Ozawa, Naoya; Tanaka, Masayoshi; Morisaki, Tomohiro

    2015-11-01

    Optical vortex beams have a potential to make a new Doppler measurement, because not only parallel but perpendicular movement of atoms against the beam axis causes the Doppler shift of their resonant absorption frequency. As the first step of a proof-of-principle experiment, we have performed the optical vortex laser absorption spectroscopy for metastable argon neutrals in an ECR plasma produced in the HYPER-I device at the National Institute for Fusion Science, Japan. An external cavity diode laser (TOPTICA, DL100) of which center wavelength was 696.735 nm in vacuum was used for the light source. The Hermite-Gaussian (HG) beam was converted into the Laguerre-Gaussian (LG) beam (optical vortex) by a computer-generated hologram displayed on the spatial light modulator (Hamamatsu, LCOS-SLM X10468-07). In order to make fast neutral flow across the LG beam, a high speed solenoid valve system was installed on the HYPER-I device. Initial results including the comparison of absorption spectra for HG and LG beams will be presented. This study was supported by NINS young scientists collaboration program for cross-disciplinary study, NIFS collaboration research program (NIFS13KOAP026), and JSPS KAKENHI grant number 15K05365.

  2. Use of Zeeman atomic absorption spectroscopy for the measurement of mercury in oil shale gases

    Energy Technology Data Exchange (ETDEWEB)

    Girvin, D.C.; Hadeishi, T.; Fox, J.P.

    1979-03-01

    A technique to continuously measure total mercury in a gas stream in the presence of high concentrations of organics, smoke, oil mist, and other interfering substances is described. The technique employees Zeeman atomic absorption (ZAA) spectroscopy as the mercury detector, which has been successfully used to measure mercury in oil shale offgases. The instrument consists of a light source which provides the 2537 A mercury emission line; a furnace-absorption tube assembly where the sample is vaporized and swept into the light path and a detector which converts the signal into an ac voltage for processing. Sample gas is heated to 900/sup 0/C in the furnace-absorption tube assembly aligned with the optical axis of the ZAA spectrometer. The 2537 A mercury emission line (..pi..) and a reference line (sigma) are generated by a single discharge lamp operated in a 15 kG magnetic field. The difference between the ..pi.. and sigma components is taken by a lock-in-amplifier and converted to a signal which is proportional to the amount of mercury in the gas.

  3. Measurements of Iodine Monoxide Levels During the CAST Campaign Using Broadband Cavity Enhanced Absorption Spectroscopy

    Science.gov (United States)

    Harris, N. R. P.; Popoola, O. A.; McLeod, M.; Ouyang, B.; Jones, R. L.

    2014-12-01

    Iodine monoxide (IO) has been regarded as an important radical involved in the ozone destruction in the remote marine boundary layer. Here we presented the first in situ aircraft measurements of IO using broadband cavity enhanced absorption spectroscopy with 1s -sensitivity of ~1.5 ppt Hz-1/2 on the surface level during the Coordinated Airborne Studies in the Tropics (CAST) campaign between January - February 2014. IO was retrieved from analysis of absorption spectrum recorded between 415 nm - 452.5 nm. Instrument baseline corresponding to the "zero" signal of IO was obtained by injection of ~20 ppb of nitric oxide (NO) into the sample air at chosen frequency and period. No clear absorption feature was observable from the spectra by eye with up to 100 seconds averaging, pointing to very low mixing ratios (<~0.5 ppt) of IO over the sampled area. A small positive bias (~0.3 ppt) of IO (against the baseline signal during NO titration) was obtained in the statistical histogram of retrieved IO from average of each straight and level run, but little altitude dependence was noted. In summary, our observation appears to support the existence of IO in the remote marine boundary above the Pacific Ocean at sub ppt levels, but the limited sensitivity precludes us from quantifying spatial gradients more accurately.

  4. Fluorescence Spectroscopy Applied to Monitoring Biodiesel Degradation: Correlation with Acid Value and UV Absorption Analyses

    Directory of Open Access Journals (Sweden)

    Maydla dos Santos Vasconcelos

    2018-01-01

    Full Text Available The techniques used to monitor the quality of the biodiesel are intensely discussed in the literature, partly because of the different oil sources and their intrinsic physicochemical characteristics. This study aimed to monitor the thermal degradation of the fatty acid methyl esters of Sesamum indicum L. and Raphanus sativus L. biodiesels (SILB and RSLB, resp.. The results showed that both biodiesels present a high content of unsaturated fatty acids, ∼84% (SILB and ∼90% (RSLB. The SILB had a high content of polyunsaturated linoleic fatty acid (18  :  2, about 49%, and the oleic monounsaturated (18  :  1, ∼34%. On the other hand, RSLB presented a considerable content of linolenic fatty acid (18  :  3, ∼11%. The biodiesel samples were thermal degraded at 110°C for 48 hours, and acid value, UV absorption, and fluorescence spectroscopy analysis were carried out. The results revealed that both absorption and fluorescence presented a correlation with acid value as a function of degradation time by monitoring absorptions at 232 and 270 nm as well as the emission at 424 nm. Although the obtained correlation is not completely linear, a direct correlation was observed in both cases, revealing that both properties can be potentially used for monitoring the biodiesel degradation.

  5. Polarized x-ray absorption spectroscopy for the study of superconductors and magnetic materials

    Science.gov (United States)

    Ramanathan, Mohan; Alp, Esen E.; Mini, Susan M.; Salem-Sugui, S.; Bommannavar, A.

    1991-11-01

    Synchrotron radiation is a good source of polarized radiation in the x-ray regime. The radiation obtained from a bending magnet source is linearly polarized in the bending plane and has a varying degree of circular polarization away from the bending plane. This feature of synchrotron radiation can be taken advantage of with proper optics to selectively use the type of polarized radiation required for the experiment in question. Linear polarized radiation is used to study the anisotropic nature of electronic and atomic structure by x-ray absorption techniques from single crystal and oriented powder samples. We will give a specific example of the use of linearly polarized x-ray absorption spectroscopy measurements for the study of the magnetically oriented layered copper oxide superconductors. While such linear dichroism measurements help identify the symmetry of the empty electronic states, circular dichroism measurements in magnetic systems help in determining the spin contribution to the absorption process. We will discuss magnetic circular dichroism measurements of the ordered-disordered invar alloy Fe(subscript 3)Pt.

  6. Effect of back reflectors on photon absorption in thin-film amorphous silicon solar cells

    Science.gov (United States)

    Hossain, Mohammad I.; Qarony, Wayesh; Hossain, M. Khalid; Debnath, M. K.; Uddin, M. Jalal; Tsang, Yuen Hong

    2017-10-01

    In thin-film solar cells, the photocurrent conversion productivity can be distinctly boosted-up utilizing a proper back reflector. Herein, the impact of different smooth and textured back reflectors was explored and effectuated to study the optical phenomena with interface engineering strategies and characteristics of transparent contacts. A unique type of wet-chemically textured glass-substrate 3D etching mask used in superstrate (p-i-n) amorphous silicon-based solar cell along with legitimated back reflector permits joining the standard light-trapping methodologies, which are utilized to upgrade the energy conversion efficiency (ECE). To investigate the optical and electrical properties of solar cell structure, the optical simulations in three-dimensional measurements (3D) were performed utilizing finite-difference time-domain (FDTD) technique. This design methodology allows to determine the power losses, quantum efficiencies, and short-circuit current densities of various layers in such solar cell. The short-circuit current densities for different reflectors were varied from 11.50 to 13.27 and 13.81 to 16.36 mA/cm2 for the smooth and pyramidal textured solar cells, individually. Contrasted with the comparable flat reference cell, the short-circuit current density of textured solar cell was increased by around 24%, and most extreme outer quantum efficiencies rose from 79 to 86.5%. The photon absorption was fundamentally improved in the spectral region from 600 to 800 nm with no decrease of photocurrent shorter than 600-nm wavelength. Therefore, these optimized designs will help to build the effective plans next-generation amorphous silicon-based solar cells.

  7. Absorption Enhancement in "Giant" Core/Alloyed-Shell Quantum Dots for Luminescent Solar Concentrator.

    Science.gov (United States)

    Zhao, Haiguang; Benetti, Daniele; Jin, Lei; Zhou, Yufeng; Rosei, Federico; Vomiero, Alberto

    2016-10-01

    Luminescent solar concentrators (LSCs) can potentially reduce the cost of solar cells by decreasing the photoactive area of the device and boosting the photoconversion efficiency (PCE). This study demonstrates the application of "giant" CdSe/Cd x Pb 1- x S core/shell quantum dots (QDs) as light harvesters in high performance LSCs with over 1.15% PCE. Pb addition is critical to maximize PCE. First, this study synthesizes "giant" CdSe/Cd x Pb 1- x S QDs with high quantum yield (40%), narrow size distribution (<10%), and stable photoluminescence in a wide temperature range (100-300 K). Subsequently these thick alloyed-shell QDs are embedded in a polymer matrix, resulting in a highly transparent composite with absorption spectrum covering the range 300-600 nm, and are applied as active material for prototype LSCs. The latter exhibits a 15% enhancement in efficiency with respect to 1% PCE of the pure-CdS-shelled QDs. This study attributes this increase to the contribution of Pb doping. The results demonstrate a straightforward approach to enhance light absorption in "giant" QDs by metal doping, indicating a promising route to broaden the absorption spectrum and increase the efficiency of LSCs. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Solar Absorption Refrigeration System for Air-Conditioning of a Classroom Building in Northern India

    Science.gov (United States)

    Agrawal, Tanmay; Varun; Kumar, Anoop

    2015-10-01

    Air-conditioning is a basic tool to provide human thermal comfort in a building space. The primary aim of the present work is to design an air-conditioning system based on vapour absorption cycle that utilizes a renewable energy source for its operation. The building under consideration is a classroom of dimensions 18.5 m × 13 m × 4.5 m located in Hamirpur district of Himachal Pradesh in India. For this purpose, cooling load of the building was calculated first by using cooling load temperature difference method to estimate cooling capacity of the air-conditioning system. Coefficient of performance of the refrigeration system was computed for various values of strong and weak solution concentration. In this work, a solar collector is also designed to provide required amount of heat energy by the absorption system. This heat energy is taken from solar energy which makes this system eco-friendly and sustainable. A computer program was written in MATLAB to calculate the design parameters. Results were obtained for various values of solution concentrations throughout the year. Cost analysis has also been carried out to compare absorption refrigeration system with conventional vapour compression cycle based air-conditioners.

  9. Studies of hydrogen incorporation in hydrogenated amorphous carbon films by infrared absorption spectroscopy

    International Nuclear Information System (INIS)

    Alameh, R.; Bounouh, Y.; Sadki, A.; Naud, C.; Theye, M.L.

    1997-01-01

    Author.Hydrogenated amorphous carbon (a-C:H) films presently attract considerable interest because of their potential applications in the domain of multifunctional coatings: transparent in the infrared, very hard, chemically inert, etc...This material is rather complex since it contains C atoms in both sp 3 (diamond) and sp 2 (graphite) electronic configurations, as well as a large concentration of H atoms. Its properties are strongly dependent on the deposition conditions which determine the film microstructure, i.e. the relative proportions of sp 3 and sp 2 C sites, their connection in the network and the hydrogen bonding modes. It has been suggested that the sp 2 C sites tend to cluster into unsaturated chains ans rings, which are then embedded in the sp 3 C sites m atrix . Hydrogen incorporation plays a crucial role in this intrinsic microheterogeneity, which determines the electronic properties, and especially the gap value, of a-C:H. We here present and discuss the results of Fourrier transform infrared absorption spectroscopy measurements performed on a-C:H films prepared under different conditions and submitted to controlled annealing cycles, which exhibit quite different optical gap values (from 1 to 2.5 eV). We carefully analyze the absorption bands detected in the 400-7500 cm -1 spectral range in terms of the vibration modes of C-H and C-C bonds in different local environments and we interpret the results in relation with the film microstructure and optical properties. Special attention is also paid to the absorption background and to the variations of the whole absorption spectra with measurement temperature

  10. INTEGRAL FIELD SPECTROSCOPY OF AGN ABSORPTION OUTFLOWS: MRK 509 AND IRAS F04250–5718

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Guilin; Arav, Nahum [Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States); Rupke, David S. N., E-mail: glliu@vt.edu [Department of Physics, Rhodes College, Memphis, TN 38112 (United States)

    2015-11-15

    Ultraviolet (UV) absorption lines provide abundant spectroscopic information enabling the probe of the physical conditions in active galactic nucleus (AGN) outflows, but the outflow radii (and the energetics consequently) can only be determined indirectly. We present the first direct test of these determinations using integral field unit (IFU) spectroscopy. We have conducted Gemini IFU mapping of the ionized gas nebulae surrounding two AGNs, whose outflow radii have been constrained by UV absorption line analyses. In Mrk 509, we find a quasi-spherical outflow with a radius of 1.2 kpc and a velocity of ∼290 km s{sup −1}, while IRAS F04250–5718 is driving a biconical outflow extending out to 2.9 kpc, with a velocity of ∼580 km s{sup −1} and an opening angle of ∼70°. The derived mass flow rate ∼5 and >1 M{sub ⊙} yr{sup −1}, respectively, and the kinetic luminosity ≳1 × 10{sup 41} erg s{sup −1} for both. Adopting the outflow radii and geometric parameters measured from IFU, absorption line analyses would yield mass flow rates and kinetic luminosities in agreement with the above results within a factor of ∼2. We conclude that the spatial locations, kinematics, and energetics revealed by this IFU emission-line study are consistent with pre-existing UV absorption line analyses, providing a long-awaited direct confirmation of the latter as an effective approach for characterizing outflow properties.

  11. [Measurement on gas temperature distribution by tunable diode laser absorption spectroscopy].

    Science.gov (United States)

    Li, Ning; Yan, Jian-hua; Wang, Fei; Chi, Yong; Cen, Ke-fa

    2008-08-01

    The technique of tunable diode laser absorption spectroscopy (TDLAS) can be used for gas temperature distribution measurement by scanning multiple gas absorption lines with a tunable diode laser. The fundamental of gas temperature distribution measurement by TDLAS is introduced in the present paper, and the discretization strategy of equation for gas absorption is also given here. Using constrained linear least-square fitting method, the gas temperature distribution can be calculated with the help of physical constraints under the condition of uniform gas concentration and pressure. Based on the spectral parameters of four CO absorption lines near 6330 cm(-1) from HITRAN database, the model of two-temperature distribution at 300 and 600 K with each path length of 55 cm was set up. The effects of relative measurement error and different path length constraints of temperature bins on the gas temperature distribution measurement results were simulated by constrained linear least-square fitting. The results show that the temperature distribution calculation error increases as the relative measurement error rises. A measurement error of 5% could lead to a maximum relative error of 11%, and an average relative error of 2.2% for calculation result. And the weak physical constraints of path length for temperature bins could increase the calculation result error during the process of constrained linear least-square fitting. By setting up the model of two-temperature distribution with gas cells at room temperature as the cold section and in tube furnace as the hot section, the experiment of gas temperature distribution measurement in lab was carried out. Using four absorption lines of CO near 6330 cm(-1) scanned by VCSEL diode laser, and fitting the background laser intensity without absorption by the cubic polynomial to get the baseline signal, the integrals of spectral absorbance for gas temperature distribution measurement can be calculated. The relative calculation

  12. Cascading metallic gratings for broadband absorption enhancement in ultrathin plasmonic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Long; Sun, Fuhe [Key Laboratory of Nanodevices and Applications-CAS and Collaborative Innovation Center of Suzhou Nano Science and Technology, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences (CAS), Suzhou 215123 (China); Chen, Qin, E-mail: qchen2012@sinano.ac.cn [Key Laboratory of Nanodevices and Applications-CAS and Collaborative Innovation Center of Suzhou Nano Science and Technology, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences (CAS), Suzhou 215123 (China); Peking University Shenzhen SOC Key Laboratory, PKU-HKUST Shenzhen-Hong Kong Institute, Hi-Tech Industrial Park South, Shenzhen 518057 (China)

    2014-04-14

    The incorporation of plasmonic nanostructures in the thin-film solar cells (TFSCs) is a promising route to harvest light into the nanoscale active layer. However, the light trapping scheme based on the plasmonic effects intrinsically presents narrow-band resonant enhancement of light absorption. Here we demonstrate that by cascading metal nanogratings with different sizes atop the TFSCs, broadband absorption enhancement can be realized by simultaneously exciting multiple localized surface plasmon resonances and inducing strong coupling between the plasmonic modes and photonic modes. As a proof of concept, we demonstrate of 66.5% in the photocurrent in an ultrathin amorphous silicon TFSC with two-dimensional cascaded gratings over the reference cell without gratings.

  13. Cascading metallic gratings for broadband absorption enhancement in ultrathin plasmonic solar cells

    International Nuclear Information System (INIS)

    Wen, Long; Sun, Fuhe; Chen, Qin

    2014-01-01

    The incorporation of plasmonic nanostructures in the thin-film solar cells (TFSCs) is a promising route to harvest light into the nanoscale active layer. However, the light trapping scheme based on the plasmonic effects intrinsically presents narrow-band resonant enhancement of light absorption. Here we demonstrate that by cascading metal nanogratings with different sizes atop the TFSCs, broadband absorption enhancement can be realized by simultaneously exciting multiple localized surface plasmon resonances and inducing strong coupling between the plasmonic modes and photonic modes. As a proof of concept, we demonstrate of 66.5% in the photocurrent in an ultrathin amorphous silicon TFSC with two-dimensional cascaded gratings over the reference cell without gratings

  14. X-ray Absorption Spectroscopy Unveils the Formation of Gold Nanoparticles in Corn X-ray Absorption Spectroscopy Unveils the Formation of Gold Nanoparticles in Corn

    Directory of Open Access Journals (Sweden)

    Gustavo Cruz-Jiménez

    2012-02-01

    Full Text Available En este estudio se determinó, mediante espectroscopía de absorción de rayos-X, la posible biotransformación de oro en maíz (variedad Golden que se germinó y creció en KAuCl4. Adicionalmente se investigó el efecto de la tiourea y el tiocianato de amonio en la absorción de oro por la planta de maíz. Los resultados indicaron que concentraciones menores a 160 mg Au/L, no afectaron la germinación o el crecimiento de las plántulas. Tanto la tiourea como el tiocianato de amonio incrementaron 6 veces el contenido de oro en las raíces, mientras que la tiourea provocó un incremento de 10 veces la concentración de oro en tallos con respecto a los tratamientos sin este compuesto. El 91% del oro en el maíz se encontró como Au(0 y el resto como Au(III. Los análisis de estructura fi na revelaron que el oro se encontraba con un número de coordinación de 9,5 aproximadamente a 2,86 Å, indicando una esfera de coordinación incompleta, lo cual implica la presencia de una nano-fase. Usando la ecuación de Borowski se determinó que las nanopartículas tenían un tamaño promedio de 10,36 nm.In this study, X-ray absorption spectroscopy was used to determine the possible gold biotransformation by Zea mays (corn var. Golden, germinated and grown in a medium spikedwith KAuCl4. In addition, the gold uptake capacity of corn assisted by thiourea and ammoniumthiocyanate was investigated. Results showed that up to 160 mg/L, gold did no treduce corn seed germination or plant growth. Both thiourea and ammonium thiocyanateresulted in a 6-fold increase of gold concentration in roots and thiourea promoted a 10-fold increase of gold concentration in shoots. X-ray absorption near edge structure studies demonstrated that approximately 91% of the gold present in plant samples was Au(0. Theremaining 9% was present as Au(III. In addition, extended X-ray absorption fi ne structureresults showed that in corn roots, the gold coordination number was around 9

  15. Laser absorption spectroscopy using lead salt and quantum cascade tunable lasers

    Science.gov (United States)

    Namjou-Khales, Khosrow

    A new class of analytic instruments based on the detection of chemical species through their spectroscopic absorption 'fingerprint' is emerging based on the use of tunable semiconductor lasers as the excitation source. Advantages of this approach include compact device size, in-line measurement capability, and large signal-bandwidth product. To realize these advantages will require the marriage of laser devices with broad tunability in the infrared spectral range with sophisticated signal processing techniques. Currently, commercial devices based on short wavelength telecommunications type lasers exist but there is potential for much more versatile instruments based on longer wavelength operation. This thesis is divided into two parts. In the first part I present a theoretical analysis and experimental characterization of frequency and wavelength modulation spectroscopy using long wavelength infrared tunable lasers. The experimental measurements were carried out using commercially available lead salt lasers and excellent agreement is found between theoretically predicted performance and experimental verification. The lead salt laser has several important drawbacks as a source in practical instrumentation. In the second part of the thesis I report on the use of the quantum cascade (QC) laser for use in sensitive absorption spectroscopy. The QC laser is a new type of tunable device developed at Bell Laboratories. It features broad infrared tunability, single mode distributed feedback operation, and near room temperature lasing. Using the modulation techniques developed originally for the lead salt lasers, the QC laser was used to detect Nsb2O and other small molecules with absorption features near 8 mum wavelength. The noise equivalent absorption for our measurements was 5× 10sp{-5}/sqrt{Hz} which corresponds to a detection limit of ˜0.25 ppm-m/sqrt{Hz} for Nsb2O. The QC laser sensitivity was found to be limited by excess amplitude modulation in the detection

  16. Light trapping and near-unity solar absorption in a three-dimensional photonic-crystal.

    Science.gov (United States)

    Kuang, Ping; Deinega, Alexei; Hsieh, Mei-Li; John, Sajeev; Lin, Shawn-Yu

    2013-10-15

    We report what is to our knowledge the first observation of the effect of parallel-to-interface-refraction (PIR) in a three-dimensional, simple-cubic photonic-crystal. PIR is an acutely negative refraction of light inside a photonic-crystal, leading to light-bending by nearly 90 deg over broad wavelengths (λ). The consequence is a longer path length of light in the medium and an improved light absorption beyond the Lambertian limit. As an illustration of the effect, we show near-unity total absorption (≥98%) in λ=520-620 nm and an average absorption of ~94% over λ=400-700 nm for our α-Si:H photonic-crystal sample of an equivalent bulk thickness of t˜=450 nm. Furthermore, we have achieved an ultra-wide angular acceptance of light over θ=0°-80°. This demonstration opens up a new door for light trapping and near-unity solar absorption over broad λs and wide angles.

  17. Simulation and experimental investigation of solar absorption cooling system in Reunion Island

    Energy Technology Data Exchange (ETDEWEB)

    Praene, Jean Philippe; Marc, Olivier; Lucas, Franck; Miranville, Frederic [Physique et Ingenierie Mathematique appliquees a l' Energie et a l' Environnement Laboratory (PIMENT), Universite de la Reunion, Departement Sciences du Batiment et de l' Environnement, 117 Rue du General Ailleret, 97430 Tampon (France)

    2011-03-15

    With the development of technologies and the fast increase of our population we will need to adjust the conventional electrical source to meet the continuous increasing demand. Since the energy cost as well as the environmental awareness is growing fast, technologies using renewable energies appear as an interesting alternative. The aim of this research is to present a solar-driven 30 kW LiBr/H{sub 2}O single-effect absorption cooling system which has been designed and installed at Institut Universitaire Technologique of Saint Pierre. The first part of this article deals with the simulation of the solar thermal plant. A pilot plant has been setup as part of RAFSOL which is a research program managed by the national research agency (ANR). (author)

  18. A solar absorption refrigeration system operating with the mixture ammonia-lithium nitrate

    Energy Technology Data Exchange (ETDEWEB)

    Rivera, W.; Martinez, F.; Garcia-Valladares, O. [Centro de Investigacion en Energia de la Univ. Nacional Autonoma de Mexico, Mor (Mexico); Rivera, C.O. [Univ. Veracruzana, Campus Coatzacoalcos (Mexico)

    2007-07-01

    An intermittent solar absorption refrigeration system for ice production operating with the ammonia-lithium nitrate mixture has been developed in the Centro de Investigacion en Energia of the Universidad Nacional Autonoma de Mexico. The system consists basically of a compound parabolic concentrator (CPC), a generator-absorber, a condenser, a condensate tank, an expansion valve and an evaporator. The system was evaluated in sunny days with insolations above 20 MJ/m{sup 2}-day at different condenser temperatures. The generator temperatures varied from 108 to 121 C and the evaporator temperatures inside the camera from -8 to 0 C. The coefficients of performance (COP) varied from 0.13 to 0.26 depending of the operating temperatures of the system and the solar irradiation. (orig.)

  19. Investigation of Absorption Cooling Application Powered by Solar Energy in the South Coast Region of Turkey

    Science.gov (United States)

    Babayigit, O.; Aksoy, M. H.; Ozgoren, M.; Solmaz, O.

    2013-04-01

    In this study, an absorption system using ammonia-water (NH3-H2O) solution has been theoretically examined in order to meet the cooling need of a detached building having 150 m2 floor area for Antalya, Mersin and Mugla provinces in Turkey. Hourly dynamic cooling load capacities of the building were determined by using Radiant Time Series (RTS) method in the chosen cities. For the analysis, hourly average meteorological data such as atmospheric air temperature and solar radiation belonging to the years 1998-2008 are used for performance prediction of the proposed system. Thermodynamic relations for each component of absorption cooling system is explained and coefficients of performance of the system are calculated. The maximum daily total radiation data were calculated as 7173 W/m2day on July 15, 7277 W/m2 day on July 19 and 7231 W/m2day on July 19 for Mersin, Antalya and Mugla, respectively on the 23° toward to south oriented panels from horizontal surface. The generator operating temperatures are considered between 90-130°C and the best result for 110°C is found the optimum degree for maximum coefficient of performance (COP) values at the highest solar radiation occurred time during the considered days for each province. The COP values varies between 0.521 and 0.530 for the provinces. In addition, absorber and condenser capacities and thermal efficiency for the absorption cooling system were calculated. The necessary evacuated tube collector area for the different provinces were found in the range of 45 m2 to 47 m2. It is shown that although the initial investment cost is higher for the proposed absorption cooling system, it is economically feasible because of its lower annual operation costs and can successfully be operated for the considered provinces.

  20. New Solutions for Solar Absorption Refrigeration Systems and Air Conditioning Systems

    Directory of Open Access Journals (Sweden)

    Doroshenko A.V.

    2017-04-01

    Full Text Available The mission of the research includes the following objectives: the development of new circuit decisions for the alternate refrigerating systems based on the use of an open absorptive circuit and on the use of solar energy for absorbent solution regeneration; an assessment of the energy and environmental characteristics of the developed systems; obtaining of the experimental data for an assessment of the principal capabilities of the proposed new solar air-conditioning systems. The multistage principle of the creation of drying and cooling contours with the increase of concentration of absorbent on cooler steps is offered. The absorber with internal steam cooling allowing the improvement of the scheme of the alternate refrigerating system is developed. On the basis of the obtained experimental data the analysis of the main opportunities of the developed solar air-conditioning systems was made which showed that the created systems: provide the required comfortable parameters indoors without engaging of traditional refrigerating technics; allow to use only one - or two-stage option of refrigerating system for application in the conditions of Ukraine and of Europe. In comparison with traditional vapor-compression systems, the developed solar systems provide the considerable decrease in energy consumption (to 30%, their use leads to the decrease of exhaustion of natural resources, influences less global climate change.

  1. Etalon-induced baseline drift and correction in atom flux sensors based on atomic absorption spectroscopy

    International Nuclear Information System (INIS)

    Du, Yingge; Chambers, Scott A.

    2014-01-01

    Atom flux sensors based on atomic absorption (AA) spectroscopy are of significant interest in thin film growth as they can provide unobtrusive, element specific real-time flux sensing and control. The ultimate sensitivity and performance of these sensors are strongly affected by baseline drift. Here we demonstrate that an etalon effect resulting from temperature changes in optical viewport housings is a major source of signal instability, which has not been previously considered, and cannot be corrected using existing methods. We show that small temperature variations in the fused silica viewports can introduce intensity modulations of up to 1.5% which in turn significantly deteriorate AA sensor performance. This undesirable effect can be at least partially eliminated by reducing the size of the beam and tilting the incident light beam off the viewport normal.

  2. Polarization-dependent X-ray absorption spectroscopy of MnWO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Hollmann, Nils; Hu, Zhiwei; Tjeng, Liu Hao [II. Physikalisches Institut, Universitaet zu Koeln (Germany); Bohaty, Ladislav; Becker-Bohaty, Petra [Kristallographisches Institut, Universitaet zu Koeln (Germany); Tanaka, Arata [Department of Quantum Matter, Hiroshima University (Japan)

    2008-07-01

    Multiferroic materials which combine magnetism and ferroelectricity currently attract considerable attention. One of the recently discovered multiferroic materials is MnWO{sub 4} (Huebnerite). It belongs to the group of multiferroics where a spontaneous electric polarization is caused by a spiral magnetic structure with a spin rotation axis not coinciding with the propagation vector. To investigate the details of this astonishing combination of electronic and magnetic properties, we look at the electronic structure with the use of polarization-dependent X-ray absorption spectroscopy on single crystals of MnWO{sub 4}. The analysis of the experimental data on the L-edge of Mn is done by a configuration interaction calculation and is discussed.

  3. [Desmoid fibromatosis in absorption infrared spectroscopy, emission spectral analysis and roentgen diffraction recording].

    Science.gov (United States)

    Zejkan, A; Bejcek, Z; Horejs, J; Vrbová, H; Bakosová, M; Macholda, F; Rykl, D

    1989-10-01

    The authors present results of serial quality and quantity microanalyses of bone patterns and dental tissue patterns in patient with desmoid fibromatosis. Methods of absorption spectroscopy, emission spectral analysis and X-ray diffraction analysis with follow-up to x-ray examination are tested. The above mentioned methods function in a on-line system by means of specially adjusted monitor unit which is controlled centrally by the computer processor system. The whole process of measurement is fully automated and the data obtained are recorded processed in the unit data structure classified into index sequence blocks of data. Serial microanalyses offer exact data for the study of structural changes of dental and bone tissues which manifest themselves in order of crystal grid shifts. They prove the fact that microanalyses give new possibilities in detection and interpretation of chemical and structural changes of apatite cell.

  4. Degree of dissociation measured by FTIR absorption spectroscopy applied to VHF silane plasmas

    International Nuclear Information System (INIS)

    Sansonnens, L.; Howling, A.A.; Hollenstein, C.

    1997-10-01

    In situ Fourier transform infrared (FTIR) absorption spectroscopy has been used to determine the fractional depletion of silane in a radio-frequency (rf) glow discharge. The technique used a simple single pass arrangement and was implemented in a large area industrial reactor for deposition of amorphous silicon. Measurements were made on silane plasmas for a range of excitation frequencies. It was observed that at constant plasma power, the fractional depletion increased from 35% at 13.56 MHz to 70% at 70 MHz. With a simple model based on the density continuity equations in the gas phase, it was shown that this increase is due to a higher dissociation rate and is largely responsible for the observed increase in the deposition rate with the frequency. (author) 5 figs., 30 refs

  5. Determination of cadmium in whole blood and urine by Zeeman atomic absorption spectroscopy.

    Science.gov (United States)

    Pleban, P A; Pearson, K H

    1979-12-17

    Direct determination of cadmium in whole blood and urine can be achieved using Zeeman effect flameless atomic absorption spectroscopy. Within-run precision studies for whole blood cadmium determinations gave relative standard deviations of 11.3% and 6.3% for 0.53 micrograms/l and 3.16 micrograms/l, respectively. Within-run precision studies for the urine analyses yielded relative standard deviations of 11.3% and 5.2% for 0.62 micrograms/l and 2.48 micrograms/l, respectively. The detection limit is 0.12 micrograms/l in the diluted specimens. Thus, this methodology may be used to quantitate normal and toxic cadmium levels in whole blood and urine.

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

    Science.gov (United States)

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

    2016-02-01

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

  7. High-resolution x-ray absorption spectroscopy studies of metal compounds in neurodegenerative brain tissue

    Science.gov (United States)

    Collingwood, J. F.; Mikhaylova, A.; Davidson, M. R.; Batich, C.; Streit, W. J.; Eskin, T.; Terry, J.; Barrea, R.; Underhill, R. S.; Dobson, J.

    2005-01-01

    Fluorescence mapping and microfocus X-ray absorption spectroscopy are used to detect, locate and identify iron biominerals and other inorganic metal accumulations in neurodegenerative brain tissue at sub-cellular resolution (autopsy brain tissue. Technical developments include use of microfocus diffraction to obtain structural information about biominerals in-situ, and depositing sample location grids by lithography for the location of anomalies by conventional microscopy. The combined techniques provide a breakthrough in the study of both intra- and extra-cellular iron compounds and related metals in tissue. The information to be gained from this approach has implications for future diagnosis and treatment of neurodegeneration, and for our understanding of the mechanisms involved.

  8. The Optical Absorption Coefficient of Maize Grains Investigated by Photoacoustic Spectroscopy

    Science.gov (United States)

    Rodríguez-Páez, C. L.; Carballo-Carballo, A.; Rico-Molina, R.; Hernández-Aguilar, C.; Domínguez-Pacheco, A.; Cruz-Orea, A.; Moreno-Martínez, E.

    2017-01-01

    In the maize and tortilla industry, it is important to characterize the color of maize ( Zea mays L.) grain, as it is one of the attributes that directly affect the quality of the tortillas consumed by the population. For this reason, the availability of alternative techniques for assessing and improving the quality of grain is valued. Photoacoustic spectroscopy has proven to be a useful tool for characterizing maize grain. So, the objective of the present study was to determine the optical absorption coefficient β of the maize grain used to make tortillas from two regions of Mexico: (a) Valles Altos, 2012-2013 production cycle and (b) Guasave, Sinaloa, 2013-2014 production cycle. Traditional reflectance measurements, physical characteristics of the grain and nutrient content were also calculated. The experimental results show different characteristics for maize grains.

  9. The application of synchrotron x-ray absorption spectroscopy to problems of industrial heterogeneous catalysis

    International Nuclear Information System (INIS)

    Meitzner, G.

    1994-01-01

    A fundamental understanding of catalytic chemistry is valuable for fine-tuning existing processes and for inventing new ones. However, active phases are hard to study, being typically dilute species in amorphous solids comprising many elements. X-ray Absorption Spectroscopy (XAS) can be applied to most catalysts under the appropriate in situ conditions. The ability is unique in observing all the trace elements in the catalysts forming active phases, poisons, and catalysts for unwanted side reactions. Every spectrum contains independent information on the average chemical state, and physical environment, of absorbing atoms. This information can yield new processes, and improvements in existing ones, after the rate of empirical advances in a technology has diminished. The authors discuss XAS studies of metallic and non-metallic components in industrial heterogeneous catalysts. The novel observations made possible by in situ measurement conditions are emphasized

  10. Identification of minority compounds in natural ilmenites by X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Klepka, M.T.; Lawniczak-Jablonska, K.; Wolska, A.; Jablonski, M.

    2010-01-01

    Research highlights: → White pigment TiO 2 production process. → The principal component analysis using XANES. → Ilmenite accompanying chemical compounds identification. → Chemical binding of Mg in ilmenite depends on the climatic and geological conditions. -- Abstract: Natural ilmenites are used all over the world as raw materials in white pigment (TiO 2 ) production. Besides the FeTiO 3 in the raw material many other compounds are present. The chemical compounds based on the minority elements influence quality of the final product and are difficult to identify. The knowledge about chemical bonding of the minor elements enables to properly adjust chemical reactions during production processes and to improve quality of the final product. In this paper the X-ray absorption spectroscopy (XAS) identification of the chemical compounds formed by Mg, Mn and Cr in natural ilmenites originating from different places is presented.

  11. Tin Valence and Local Environments in Silicate Glasses as Determined From X-ray Absorption Spectroscopy

    International Nuclear Information System (INIS)

    McKeown, D.; Buechele, A.; Gan, H.; Pegg, I.

    2008-01-01

    X-ray absorption spectroscopy (XAS) was used to characterize the tin (Sn) environments in four borosilicate glass nuclear waste formulations, two silicate float glasses, and three potassium aluminosilicate glasses. Sn K-edge XAS data of most glasses investigated indicate Sn4+O6 units with average Sn-O distances near 2.03 Angstroms. XAS data for a float glass fabricated under reducing conditions show a mixture of Sn4+O6 and Sn2+O4 sites. XAS data for three glasses indicate Sn-Sn distances ranging from 3.43 to 3.53 Angstroms, that suggest Sn4+O6 units linking with each other, while the 4.96 Angstroms Sn-Sn distance for one waste glass suggests clustering of unlinked Sn4+O6 units.

  12. Diode laser absorption spectroscopy for process control: Sensor system design methodology

    International Nuclear Information System (INIS)

    Berzins, L.V.; Anklam, T.M.; Chambers, F.; Galanti, S.; Haynam, C.A.; Worden, E.F.

    1995-03-01

    A laser absorption spectroscopy (LAS) system has been developed at Lawrence Livermore National Laboratory (LLNL) for process control. LAS has proven itself to be an accurate and reliable method to monitor both density and composition. In this paper the important features and components of an industrial LAS diagnostic are described. Application of this approach to vaporization processes requires careful selection of the species and transitions to be monitored The relative vapor pressure, hyperfine structure, isotopic frequency shifts, and electronic temperature all effect the selection of a particular transition. In this paper we describe the methodology for choosing the optimal transition or transitions. Coevaporation of a titanium-niobium alloy is used to illustrate the methodology. In a related paper, T.M. Anklam et al describe the application of this diagnostic to monitoring and controlling composition in a physical vapor deposition process of industrial interest

  13. Instrument for x-ray absorption spectroscopy with in situ electrical control characterizations

    International Nuclear Information System (INIS)

    Huang, Chun-Chao; Chang, Shu-Jui; Yang, Chao-Yao; Tseng, Yuan-Chieh; Chou, Hsiung

    2013-01-01

    We report a synchrotron-based setup capable of performing x-ray absorption spectroscopy and x-ray magnetic circular dichroism with simultaneous electrical control characterizations. The setup can enable research concerning electrical transport, element- and orbital-selective magnetization with an in situ fashion. It is a unique approach to the real-time change of spin-polarized electronic state of a material/device exhibiting magneto-electric responses. The performance of the setup was tested by probing the spin-polarized states of cobalt and oxygen of Zn 1-x Co x O dilute magnetic semiconductor under applied voltages, both at low (∼20 K) and room temperatures, and signal variations upon the change of applied voltage were clearly detected

  14. An Attosecond Transient Absorption Spectroscopy Setup with a Water Window Attosecond source

    Science.gov (United States)

    Chew, Andrew; Yin, Yanchun; Li, Jie; Ren, Xiaoming; Wang, Yang; Wu, Yi; Chang, Zenghu

    2017-04-01

    Attosecond transient absorption, or time-resolved pump-probe spectroscopy, are excellent tools that can be used to investigate fast electron dynamics for a given atomic or molecular system. Recent push for high energy long wavelength few cycle laser sources has resulted in the production of x-ray spectra that would allow the probing of electron dynamics at the carbon k-edge in molecules such as CH4 and CO2. The motion of charges can be caused by photo-dissociation and charge migration. We present here the first results from our experimental setup where we produce a broadband attosecond pulse with spectra that stretches into the water window. National Science Foundation (1068604), Army Research Oce (W911NF-14-1-0383), Air Force Oce of Scientic Research (FA9550-15-1-0037, FA9550-16-1-0013) and the DARPA PULSE program by a Grant from AMRDEC (W31P4Q1310017).

  15. Diode laser absorption spectroscopy for studies of gas exchange in fruits

    Science.gov (United States)

    Persson, L.; Gao, H.; Sjöholm, M.; Svanberg, S.

    2006-07-01

    Gas exchange in fruits, in particular oxygen transport in apples, was studied non-intrusively using wavelength modulation diode laser absorption spectroscopy at about 761 nm, applied to the strongly scattering intact fruit structure. The applicability of the technique was demonstrated by studies of the influence of the skin to regulate the internal oxygen balance and of cling film in modifying it by observing the response of the signal from the internal oxygen gas to a transient change in the ambient gas concentration. Applications within controlled atmosphere fruit storage and modified atmosphere packaging are discussed. The results suggest that the technique could be applied to studies of a large number of problems concerning gas exchange in foods and in food packaging.

  16. Novel opportunities for time-resolved absorption spectroscopy at the X-ray free electron laser.

    Science.gov (United States)

    Patterson, B D; Abela, R

    2010-06-07

    Time-dependent X-ray Absorption Spectroscopy (XAS) measurements of chemical reaction dynamics have a time resolution which is limited by: (a) the speed and efficiency of the reaction initiation; (b) the duration of the X-ray pulses used for the measurement; and (c) the brightness of the X-ray source. X-Ray Free Electron Lasers (XFEL), which will deliver 20-100 fs pulses of X-rays, with a peak brightness which is 10(10) times that of a synchrotron, will alleviate limitations (b) and (c). Furthermore, by including a synchronized source of UV, visible, IR or THz pump radiation, the XFEL will contribute to the solution of limitation (a). The present article describes the XFEL operating principle and the generic design of an XFEL facility, emphasizing the features of particular interest to the XAS investigator.

  17. Charge Carrier Dynamics in Transition Metal Oxides Studied by Femtosecond Transient Extreme Ultraviolet Absorption Spectroscopy

    Science.gov (United States)

    Jiang, Chang-Ming

    With the ability to disentangle electronic transitions that occur on different elements and local electronic structures, time-resolved extreme ultraviolet (XUV) spectroscopy has emerged as a powerful tool for studying ultrafast dynamics in condensed phase systems. In this dissertation, a visible-pump/XUV-probe transient absorption apparatus with femtosecond resolution was constructed to investigate the carrier relaxation dynamics in semiconductors after photo-excitation. This includes timescales for carrier thermalization by carrier-carrier and carrier-phonon scattering. The 30 -- 72 eV photon energy coverage (17 -- 40 nm wavelength) generated by a table-top XUV light source is suitable for probing the 3p-to-3d core level absorptions of various transition metal oxides (TMOs) with specificities to elements and oxidation states. In Chapter 1, a brief introduction to charge carrier dynamics in semiconductor-based materials is given. In addition, fundamentals of core-level spectroscopy and the high harmonic generation (HHG) process are also addressed in this introductory chapter. Specifications of the experimental apparatus that was constructed are summarized in Chapter 2, including the design concepts and characterization of performance. Chapter 3 presents the spectral tunability of the XUV pulses generated from a semi-infinite gas cell (SIGC), as well as the data acquisition procedures. Charge carrier relaxation dynamics in Co3O4 following the charge transfer excitation pathway at 400 nm are documented in Chapter 4. In Chapter 5, various visible pump wavelengths are used to excite Co3O4 and the differences in the carrier dynamics versus excitation wavelength are considered. After selectively photoexciting a Si/TiO2 heterojunction, the resulted electron transfer process is observed and reported in Chapter 6. The concluding remarks of the dissertation are made in Chapter 7, while several ongoing time-resolved experiments are addressed in the Appendix sections.

  18. Site- and phase-selective x-ray absorption spectroscopy based on phase-retrieval calculation

    International Nuclear Information System (INIS)

    Kawaguchi, Tomoya; Fukuda, Katsutoshi; Matsubara, Eiichiro

    2017-01-01

    Understanding the chemical state of a particular element with multiple crystallographic sites and/or phases is essential to unlocking the origin of material properties. To this end, resonant x-ray diffraction spectroscopy (RXDS) achieved through a combination of x-ray diffraction (XRD) and x-ray absorption spectroscopy (XAS) techniques can allow for the measurement of diffraction anomalous fine structure (DAFS). This is expected to provide a peerless tool for electronic/local structural analyses of materials with complicated structures thanks to its capability to extract spectroscopic information about a given element at each crystallographic site and/or phase. At present, one of the major challenges for the practical application of RXDS is the rigorous determination of resonant terms from observed DAFS, as this requires somehow determining the phase change in the elastic scattering around the absorption edge from the scattering intensity. This is widely known in the field of XRD as the phase problem. The present review describes the basics of this problem, including the relevant background and theory for DAFS and a guide to a newly-developed phase-retrieval method based on the logarithmic dispersion relation that makes it possible to analyze DAFS without suffering from the intrinsic ambiguities of conventional iterative-fitting. Several matters relating to data collection and correction of RXDS are also covered, with a final emphasis on the great potential of powder-sample-based RXDS (P-RXDS) to be used in various applications relevant to practical materials, including antisite-defect-type electrode materials for lithium-ion batteries. (topical review)

  19. Theoretical comparison of single-stage and advanced absorption heat transformers used to increase solar pond's temperature

    Energy Technology Data Exchange (ETDEWEB)

    Rivera, W; Best, Roberto [Centro de Investigacion en Energia-UNAM, Temixco, Morelos (Mexico)

    2000-07-01

    Mathematical models of single-stage and advanced absorption heat transformers operating with the water/Carrol{sup T}M mixture were developed to simulate the performance of these systems coupled to a solar pond in order to increase the temperature of the useful heat produced by solar ponds. The results showed that the single-stage and the double absorption heat transformer are the most promising configuration to be coupled to solar ponds. With single-stage heat transformers it is possible to increase solar pond's temperature until 50 Celsius degrees with coefficients of performance of about 0.48 and with double absorption heat transformers until 100 Celsius degrees with coefficients of performance of 0.33. [Spanish] Se desarrollaron modelos matematicos de una sola etapa y transformadores avanzados de absorcion de calor operando con la mezcla agua/Carrol{sup T}M para simular el rendimiento de estos sistemas acoplados a un estanque solar con el objeto de aumentar la temperatura del calor util producido por los estanques solares. Los resultados mostraron que la etapa sencilla y el transformador de calor de absorcion doble son la configuracion mas prometedora para ser acoplado a estanques solares. Con los transformadores de calor de una sola etapa es posible aumentar la temperatura del estanque solar hasta 50 grados Celsius con coeficientes de rendimiento de alrededor de 0.48 y con transformadores de calor de doble absorcion hasta 100 grados Celsius con coeficientes de rendimiento de 0.33.

  20. Extending differential optical absorption spectroscopy for limb measurements in the UV

    Directory of Open Access Journals (Sweden)

    J. Puķīte

    2010-05-01

    Full Text Available Methods of UV/VIS absorption spectroscopy to determine the constituents in the Earth's atmosphere from measurements of scattered light are often based on the Beer-Lambert law, like e.g. Differential Optical Absorption Spectroscopy (DOAS. While the Beer-Lambert law is strictly valid for a single light path only, the relation between the optical depth and the concentration of any absorber can be approximated as linear also for scattered light observations at a single wavelength if the absorption is weak. If the light path distribution is approximated not to vary with wavelength, also linearity between the optical depth and the product of the cross-section and the concentration of an absorber can be assumed. These assumptions are widely made for DOAS applications for scattered light observations.

    For medium and strong absorption of scattered light (e.g. along very long light-paths like in limb geometry the relation between the optical depth and the concentration of an absorber is no longer linear. In addition, for broad wavelength intervals the differences in the travelled light-paths at different wavelengths become important, especially in the UV, where the probability for scattering increases strongly with decreasing wavelength.

    However, the DOAS method can be extended to cases with medium to strong absorptions and for broader wavelength intervals by the so called air mass factor modified (or extended DOAS and the weighting function modified DOAS. These approaches take into account the wavelength dependency of the slant column densities (SCDs, but also require a priori knowledge for the air mass factor or the weighting function from radiative transfer modelling.

    We describe an approach that considers the fitting results obtained from DOAS, the SCDs, as a function of wavelength and vertical optical depth and expands this function into a Taylor series of both quantities. The Taylor coefficients are then applied as

  1. Development of a saturated absorption spectroscopy setup at IGISOL for characterisation of Fabry-Pérot interferometers

    Energy Technology Data Exchange (ETDEWEB)

    Geldhof, S., E-mail: sarina.m.geldhof@jyu.fi; El Youbi, S.; Moore, I. D.; Pohjalainen, I. [University of Jyväskylä, Department of Physics (Finland); Sonnenschein, V.; Terabayashi, R. [Nagoya University, Department of Quantum Engineering (Japan); Voss, A. [University of Jyväskylä, Department of Physics (Finland)

    2017-11-15

    A saturated absorption spectroscopy setup was developed and optimised for the characterisation of a home-built and a commercial Fabry-Pérot interferometer (FPI). The free spectral range of these FPIs has been determined with reliable statistical and systematic errors. These FPIs will be used for accurate wavelength determination of broad- and narrowband pulsed Ti:sapphire lasers used in resonance ionisation spectroscopy experiments.

  2. Damped Lyman-alpha absorption by disk galaxies with large redshifts. III. Intermediate-resolution spectroscopy

    International Nuclear Information System (INIS)

    Turnshek, D.A.; Wolfe, A.M.; Lanzetta, K.M.; Briggs, F.H.; Cohen, R.D.

    1989-01-01

    New intermediate-resolution spectroscopy for six members of a sample of 68 moderate- to high-redshift QSOs is presented. Evidence is reported which indicates that seven strong absorption features in the QSO spectra are due to damped Ly-alpha absorption. A standard curve-of-growth analysis on five of the damped systems is performed, and relevant properties are tabulated and discussed. Six of the seven damped Ly-alpha systems have H I column densities of 2 x 10 to the 20th/sq cm or larger, while the remaining system has an H I column density of about 10 to the 20th/sq cm. It is suggested that damped Ly-alpha systems arise when a sight line intercepts a high-redshift protogalaxy disk containing a quiescent cloud component characterized by high column density and low effective velocity dispersion. At the same time, the sight line usually intercepts a broader turbulent component, which is identified as the halo, characterized by much lower column density and higher effective velocity dispersion. 42 refs

  3. Characterization of the photoreaction between DNA and aminomethyl-trimethylpsoralen using absorption and fluorescence spectroscopy

    International Nuclear Information System (INIS)

    Johnston, B.H.; Hearst, J.E.

    1981-01-01

    The use of absorption and fluorescence spectroscopy for following the progress of the photoreaction between DNA and 4'-aminomethyl-4,5',8-trimethylpsoralen (AMT) has been investigated. Absorption at long wavelengths and fluorescence both decline upon intercalation of AMT into the DNA helix. The loss of fluorescence from AMT and the accompanying appearance of monoadduct fluorescence upon irradiation by UV light can be easily followed by using the excitation beam of a spectrofluorometer as the source of irradiation and monitoring the changing emission spectrum. Where cross-link formation is possible, the subsequent decline of monoadduct fluorescence is seen as well. This suggests that the 4',5'-monoadduct is a precursor of cross-links. Both monoaddition and cross-linking are more rapid with poly d(A-T) than with calf thymus DNA or poly d(A.T). Excitation spectra can be helpful in resolving the levels of AMT and 4',5'-monoadduct when both are contributing to the emission spectrum. Some changes are observed in the emission spectrum of AMT-poly d(A.T) monoadducts after prolonged irradiation which indicate further photoreaction. (author)

  4. Optical and X-ray absorption spectroscopy in lead doped lithium fluoride crystals

    Energy Technology Data Exchange (ETDEWEB)

    Somma, F; Aloe, P; D' Acapito, F; Montereali, R M; Polosan, S; Secu, M; Vincenti, M A, E-mail: somma@fis.uniroma3.it

    2010-11-15

    LiF:Pb doped crystals were successfully grown by Kyropoulos method, starting with drying powders. The presence of Pb{sup 2+} ions in the LiF crystals were evidenced by the absorption band at 278 nm and by 375 nm photoluminescence. The presence of some other Pb structures with oxygen compounds in the as made samples was evidenced, decreasing after some annealing procedures. The local environment and valence state of Pb in LiF were studied by X-ray Absorption Spectroscopy at the Pb L{sub III} and L{sub I} edges. XANES data reveal that Pb is present as Pb{sup 2+} whereas EXAFS data show that it is incorporated in the crystal and not forming PbF{sub 2} precipitates. Identical spectra are obtained for samples as prepared and after thermal annealing up to 650 deg. C demonstrating the stability of the incorporation site. Also the concentration of Pb in the crystal has no effect on the location site of the metal as the same spectrum is obtained for specimens with different dopant concentrations.

  5. NO2 measurements in Hong Kong using LED based long path differential optical absorption spectroscopy

    Directory of Open Access Journals (Sweden)

    M. O. Wenig

    2012-05-01

    Full Text Available 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.

  6. X-ray absorption spectroscopy and EPR studies of oriented spinach thylakoid preparations

    Energy Technology Data Exchange (ETDEWEB)

    Andrews, J.C. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry]|[Lawrence Berkeley Lab., CA (United States). Structural Biology Div.

    1995-08-01

    In this study, oriented Photosystem II (PS II) particles from spinach chloroplasts are studied with electron paramagnetic resonance (EPR) and x-ray absorption spectroscopy (XAS) to determine more details of the structure of the oxygen evolving complex (OEC). The nature of halide binding to Mn is also studied with Cl K-edge and Mn EXAFS (extended x-ray absorption fine structure) of Mn-Cl model compounds, and with Mn EXAFS of oriented PS II in which Br has replaced Cl. Attention is focused on the following: photosynthesis and the oxygen evolving complex; determination of mosaic spread in oriented photosystem II particles from signal II EPR measurement; oriented EXAFS--studies of PS II in the S{sub 2} state; structural changes in PS II as a result of treatment with ammonia: EPR and XAS studies; studies of halide binding to Mn: Cl K-edge and Mn EXAFS of Mn-Cl model compounds and Mn EXAFS of oriented Br-treated photosystem II.

  7. Atomic and ionic density measurement by laser absorption spectroscopy of magnetized or non-magnetized plasmas

    International Nuclear Information System (INIS)

    Le Gourrierec, P.

    1989-11-01

    Laser absorption spectroscopy is an appreciated diagnostic in plasma physics to measure atomic and ionic densities. We used it here more specifically on metallic plasmas. Firstly, a uranium plasma was created in a hollow cathode. 17 levels of U.I and U.II (12 for U.I and 5 for U.II) are measured by this method. The results are compared with the calculated levels of two models (collisional-radiative and LTE). Secondly, the theory of absorption in presence of a magnetic field is recalled and checked. Then, low-density magnetized plasma produced on our ERIC experiment (acronym for Experiment of Resonance Ionic Cyclotron), have been diagnosed successfully. The use of this technique on a low density plasma has not yet been published to our knowledge. The transverse temperature and the density of a metastable atomic level of a barium plasma has been derived. The evolution of a metastable ionic level of this element is studied in terms of two source parameters (furnace temperature and injected hyperfrequency power) [fr

  8. Experimental study of radiative energy transport in dense plasmas by emission and absorption spectroscopy

    International Nuclear Information System (INIS)

    Dozieres, Maylis

    2016-01-01

    This PhD work is an experimental study, based on emission and absorption spectroscopy of hot and dense nanosecond laser-produced plasmas. Atomic physics in such plasmas is a complex subject and of great interest especially in the fields of astrophysics or inertial confinement fusion. On the atomic physics point of view, this means determining parameters such as the average ionization or opacity in plasmas at given electronic temperature and density. Atomic physics codes then need of experimental data to improve themselves and be validated so that they can be predictive for a wide range of plasmas. With this work we focus on plasmas whose electronic temperature varies from 10 eV to more than a hundred and whose density range goes from 10 -5 ato10 -2 g/cm 3 . In this thesis, there are two types of spectroscopic data presented which are both useful and necessary to the development of atomic physics codes because they are both characteristic of the state of the studied plasma: 1) some absorption spectra from Cu, Ni and Al plasmas close to local thermodynamic equilibrium; 2) some emission spectra from non local thermodynamic equilibrium plasmas of C, Al and Cu. This work highlights the different experimental techniques and various comparisons with atomic physics codes and hydrodynamics codes. (author) [fr

  9. X-ray Absorption Spectroscopy Characterization of Electrochemical Processes in Renewable Energy Storage and Conversion Devices

    Energy Technology Data Exchange (ETDEWEB)

    Farmand, Maryam [George Washington Univ., Washington, DC (United States)

    2013-05-19

    The development of better energy conversion and storage devices, such as fuel cells and batteries, is crucial for reduction of our global carbon footprint and improving the quality of the air we breathe. However, both of these technologies face important challenges. The development of lower cost and better electrode materials, which are more durable and allow more control over the electrochemical reactions occurring at the electrode/electrolyte interface, is perhaps most important for meeting these challenges. Hence, full characterization of the electrochemical processes that occur at the electrodes is vital for intelligent design of more energy efficient electrodes. X-ray absorption spectroscopy (XAS) is a short-range order, element specific technique that can be utilized to probe the processes occurring at operating electrode surfaces, as well for studying the amorphous materials and nano-particles making up the electrodes. It has been increasingly used in recent years to study fuel cell catalysts through application of the and #916; and mgr; XANES technique, in combination with the more traditional X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) techniques. The and #916; and mgr; XANES data analysis technique, previously developed and applied to heterogeneous catalysts and fuel cell electrocatalysts by the GWU group, was extended in this work to provide for the first time space resolved adsorbate coverages on both electrodes of a direct methanol fuel cell. Even more importantly, the and #916; and mgr; technique was applied for the first time to battery relevant materials, where bulk properties such as the oxidation state and local geometry of a cathode are followed.

  10. Far-infrared reflection-absorption spectroscopy of amorphous and polycrystalline gallium arsenide films

    International Nuclear Information System (INIS)

    Gregory, J.R.

    1992-01-01

    We have reported far-infrared reflection absorption spectra (30-320CM -1 ) at 30 and 310K for nine films of non-stoichiometric GaAs. The FIRRAS measurements were performed using the grazing incidence FIR double-modulation spectroscopy technique first described by DaCosta and Coleman. The films were fabricated by molecular beam deposition on metallized substrates for two As/Ga molecular beam flux ratios. The films were characterized by depth profilometry, IRAS, XRD, and x-ray microprobe analysis. Film thicknesses ranged from 800 to 5800 angstrom and compositions were 45-50% As for a MB flux ratio of 0.29 and 60-70% As for a ratio of 1.12. FIRRAS measurements were made and characterizations performed for as-deposited films and for 5 hour anneals at 473, 573, 673 and 723 degrees C. Vibrational spectra of the crystallized films were interpreted in terms of the exact reflectivity of a thin dielectric film on a conducting substrate, using a classical Lorentzian dielectric function for the response of the film. Resonances appearing in the open-quote forbidden close-quote region between the TO and LO frequencies were modelled with an effective medium approximation and are interpreted as arising from small-scale surface roughness. The behavior of the amorphous film spectra were examined within two models. The effective force constant model describes the variation of the reflection-absorption maxima with measured crystallite size in terms of the effective vibration frequency of 1-D atomic chains having force constants distributed according to the parameters of the crystalline-to-amorphous relaxation length and the crystalline to amorphous force constant ratio. The dielectric function continuum model uses the relaxation of the crystal momentum selection rule to calculate the reflection-absorption spectrum based on a dielectric function in which the oscillator strength is the normalized product of a constant dipole strength and the smoothed vibrational density of states

  11. Characterising legacy spent nuclear fuel pond materials using microfocus X-ray absorption spectroscopy.

    Science.gov (United States)

    Bower, W R; Morris, K; Mosselmans, J F W; Thompson, O R; Banford, A W; Law, K; Pattrick, R A D

    2016-11-05

    Analysis of a radioactive, coated concrete core from the decommissioned, spent nuclear fuel cooling pond at the Hunterston-A nuclear site (UK) has provided a unique opportunity to study radionuclides within a real-world system. The core, obtained from a dividing wall and sampled at the fill level of the pond, exhibited radioactivity (dominantly (137)Cs and (90)Sr) heterogeneously distributed across both painted faces. Chemical analysis of the core was undertaken using microfocus spectroscopy at Diamond Light Source, UK. Mapping of Sr across the surface coatings using microfocus X-ray fluorescence (μXRF) combined with X-ray absorption spectroscopy showed that Sr was bound to TiO2 particles in the paint layers, suggesting an association between TiO2 and radiostrontium. Stable Sr and Cs sorption experiments using concrete coupons were also undertaken to assess their interactions with the bulk concrete in case of a breach in the coating layers. μXRF and scanning electron microscopy showed that Sr was immobilized by the cement phases, whilst at the elevated experimental concentrations, Cs was associated with clay minerals in the aggregates. This study provides a crucial insight into poorly understood infrastructural contamination in complex systems and is directly applicable to the UK's nuclear decommissioning efforts. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  12. A flexible gas flow reaction cell for in situ x-ray absorption spectroscopy studies

    Energy Technology Data Exchange (ETDEWEB)

    Kroner, Anna B., E-mail: anna.kroner@diamond.ac.uk; Gilbert, Martin; Duller, Graham; Cahill, Leo; Leicester, Peter; Woolliscroft, Richard; Shotton, Elizabeth J. [Diamond Light Source Ltd., Diamond House, Harwell Science and Innovation Campus, Chilton, Oxfordshire, OX110DE (United Kingdom); Mohammed, Khaled M. H. [UK Catalysis Hub, Research Complex at Harwell, Rutherford Appleton Laboratory, Chilton, Oxfordshire, OX110FA (United Kingdom); School of Chemistry, University of Southampton, Southampton, SO17 1BJ (United Kingdom)

    2016-07-27

    A capillary-based sample environment with hot air blower and integrated gas system was developed at Diamond to conduct X-ray absorption spectroscopy (XAS) studies of materials under time-resolved, in situ conditions. The use of a hot air blower, operating in the temperature range of 298-1173 K, allows introduction of other techniques e.g. X-ray diffraction (XRD), Raman spectroscopy for combined techniques studies. The flexibility to use either quartz or Kapton capillaries allows users to perform XAS measurement at energies as low as 5600 eV. To demonstrate performance, time-resolved, in situ XAS results of Rh catalysts during the process of activation (Rh K-edge, Ce L{sub 3}-edge and Cr K-edge) and the study of mixed oxide membrane (La{sub 0.6}Sr{sub 0.4}Co{sub 0.2}Fe{sub 0.8}O{sub 3−δ}) under various partial oxygen pressure conditions are described.

  13. Multipitched Diffraction Gratings for Surface Plasmon Resonance-Enhanced Infrared Reflection Absorption Spectroscopy.

    Science.gov (United States)

    Petefish, Joseph W; Hillier, Andrew C

    2015-11-03

    We demonstrate the application of metal-coated diffraction gratings possessing multiple simultaneous pitch values for surface enhanced infrared absorption (SEIRA) spectroscopy. SEIRA increases the magnitude of vibrational signals in infrared measurements by one of several mechanisms, most frequently involving the enhanced electric field associated with surface plasmon resonance (SPR). While the majority of SEIRA applications to date have employed nanoparticle-based plasmonic systems, recent advances have shown how various metals and structures lead to similar signal enhancement. Recently, diffraction grating couplers have been demonstrated as a highly tunable platform for SEIRA. Indeed, gratings are an experimentally advantageous platform due to the inherently tunable nature of surface plasmon excitation at these surfaces since both the grating pitch and incident angle can be used to modify the spectral location of the plasmon resonance. In this work, we use laser interference lithography (LIL) to fabricate gratings possessing multiple pitch values by subjecting photoresist-coated glass slides to repetitive exposures at varying orientations. After metal coating, these gratings produced multiple, simultaneous plasmon peaks associated with the multipitched surface, as identified by infrared reflectance measurements. These plasmon peaks could then be coupled to vibrational modes in thin films to provide localized enhancement of infrared signals. We demonstrate the flexibility and tunability of this platform for signal enhancement. It is anticipated that, with further refinement, this approach might be used as a general platform for broadband enhancement of infrared spectroscopy.

  14. X-ray absorption and Raman spectroscopy studies of molybdenum environments in borosilicate waste glasses

    Science.gov (United States)

    McKeown, David A.; Gan, Hao; Pegg, Ian L.

    2017-05-01

    Mo-containing high-level nuclear waste borosilicate glasses were investigated as part of an effort to improve Mo loading while avoiding yellow phase crystallization. Previous work showed that additions of vanadium decrease yellow phase formation and increases Mo solubility. X-ray absorption spectroscopy (XAS) and Raman spectroscopy were used to characterize Mo environments in HLW borosilicate glasses and to investigate possible structural relationships between Mo and V. Mo XAS spectra for the glasses indicate isolated tetrahedral Mo6+O4 with Mo-O distances near 1.75 Å. V XANES indicate tetrahedral V5+O4 as the dominant species. Raman spectra show composition dependent trends, where Mo-O symmetrical stretch mode frequencies (ν1) are sensitive to the mix of alkali and alkaline earth cations, decreasing by up to 10 cm-1 for glasses that change from Li+ to Na+ as the dominant network-modifying species. This indicates that MoO4 tetrahedra are isolated from the borosilicate network and are surrounded, at least partly, by Na+ and Li+. Secondary ν1 frequency effects, with changes up to 7 cm-1, were also observed with increasing V2O5 and MoO3 content. These secondary trends may indicate MoO4-MoO4 and MoO4-VO4 clustering, suggesting that V additions may stabilize Mo in the matrix with respect to yellow phase formation.

  15. UV Absorption Spectroscopy in Water-Filled Antiresonant Hollow Core Fibers for Pharmaceutical Detection

    Directory of Open Access Journals (Sweden)

    Mona Nissen

    2018-02-01

    Full Text Available Due to a worldwide increased use of pharmaceuticals and, in particular, antibiotics, a growing number of these substance residues now contaminate natural water resources and drinking supplies. This triggers a considerable demand for low-cost, high-sensitivity methods for monitoring water quality. Since many biological substances exhibit strong and characteristic absorption features at wavelengths shorter than 300 nm, UV spectroscopy presents a suitable approach for the quantitative identification of such water-contaminating species. However, current UV spectroscopic devices often show limited light-matter interaction lengths, demand sophisticated and bulky experimental infrastructure which is not compatible with microfluidics, and leave large fractions of the sample analyte unused. Here, we introduce the concept of UV spectroscopy in liquid-filled anti-resonant hollow core fibers, with large core diameters and lengths of approximately 1 m, as a means to overcome such limitations. This extended light-matter interaction length principally improves the concentration detection limit by two orders of magnitude while using almost the entire sample volume—that is three orders of magnitude smaller compared to cuvette based approaches. By integrating the fibers into an optofluidic chip environment and operating within the lowest experimentally feasible transmission band, concentrations of the application-relevant pharmaceutical substances, sulfamethoxazole (SMX and sodium salicylate (SS, were detectable down to 0.1 µM (26 ppb and 0.4 µM (64 ppb, respectively, with the potential to reach significantly lower detection limits for further device integration.

  16. UV Absorption Spectroscopy in Water-Filled Antiresonant Hollow Core Fibers for Pharmaceutical Detection.

    Science.gov (United States)

    Nissen, Mona; Doherty, Brenda; Hamperl, Jonas; Kobelke, Jens; Weber, Karina; Henkel, Thomas; Schmidt, Markus A

    2018-02-06

    Due to a worldwide increased use of pharmaceuticals and, in particular, antibiotics, a growing number of these substance residues now contaminate natural water resources and drinking supplies. This triggers a considerable demand for low-cost, high-sensitivity methods for monitoring water quality. Since many biological substances exhibit strong and characteristic absorption features at wavelengths shorter than 300 nm, UV spectroscopy presents a suitable approach for the quantitative identification of such water-contaminating species. However, current UV spectroscopic devices often show limited light-matter interaction lengths, demand sophisticated and bulky experimental infrastructure which is not compatible with microfluidics, and leave large fractions of the sample analyte unused. Here, we introduce the concept of UV spectroscopy in liquid-filled anti-resonant hollow core fibers, with large core diameters and lengths of approximately 1 m, as a means to overcome such limitations. This extended light-matter interaction length principally improves the concentration detection limit by two orders of magnitude while using almost the entire sample volume-that is three orders of magnitude smaller compared to cuvette based approaches. By integrating the fibers into an optofluidic chip environment and operating within the lowest experimentally feasible transmission band, concentrations of the application-relevant pharmaceutical substances, sulfamethoxazole (SMX) and sodium salicylate (SS), were detectable down to 0.1 µM (26 ppb) and 0.4 µM (64 ppb), respectively, with the potential to reach significantly lower detection limits for further device integration.

  17. Quantifying the Aggregation Factor in Carbon Nanotube Dispersions by Absorption Spectroscopy

    Directory of Open Access Journals (Sweden)

    Hari Pathangi

    2014-01-01

    Full Text Available Absorption spectroscopy in the ultraviolet-visible-near infrared (UV-Vis-NIR wavelength region has been used to quantify the aggregation factor of single-walled carbon nanotubes (SWCNTs in liquid media through a series of controlled experiments. SWCNT bundles are dispersed in selected solvents using a calibrated ultrasonicator, which helps in determining the true amount of energy used in the exfoliation process. We also establish the selectivity of the centrifugation process, under the conditions used, in removing the nanotube aggregates as a function of the sonication time and the dispersion solvent. This study, along with the calibration of the sonication process, is shown to be very important for measuring the true aggregation factor of SWCNTs through a modified approach. We also show that the systematic characterization of SWCNT dispersions by optical spectroscopy significantly contributes to the success of dielectrophoresis (DEP of nanotubes at predefined on-chip positions. The presence of individually dispersed SWCNTs in the dispersions is substantiated by dielectrophoretic assembly and post-DEP electromechanical measurements.

  18. Ultrafast Transient Absorption Spectroscopy of Polymer-Based Organophotoredox Catalysts Mimicking Transition-Metal Complexes

    Science.gov (United States)

    Jamhawi, Abdelqader; Paul, Anam C.; Smith, Justin D.; Handa, Sachin; Liu, Jinjun

    2017-06-01

    Transition-metal complexes of rare earth metals including ruthenium and iridium are most commonly employed as visible-light photocatalysts. Despite their highly important and broad applications, they have many disadvantages including high cost associated with low abundance in earth crust, potential toxicity, requirement of specialized ligands for desired activity, and difficulty in recycling of metal contents as well as associated ligands. Polymer-based organophotoredox catalysts are promising alternatives and possess unique advantages such as easier synthesis from inexpensive starting material, longer excited state life time, broad range of activity, sustainability, and recyclability. In this research talk, time-resolved photoluminescence and femtosecond transient absorption (TA) spectroscopy measurements of three novel polymer-based organophotoredox catalysts will be presented. By our synthetic team, their catalytic activity has been proven in some highly valuable chemical transformations, that otherwise require transition metal complexes. Time-resolved spectroscopic investigations have demonstrated that photoinduced processes in these catalysts are similar to the transition metal complexes. Especially, intramolecular vibrational relaxation, internal conversion, and intersystem crossing from the S1 state to the T1 state all occur on a sub-picosecond timescale. The long lifetime of the T1 state ( 2-3 microsecond) renders these polymers potent oxidizing and reducing agents. A spectroscopic and kinetic model has been developed for global fitting of TA spectra in both the frequency and time domains. Implication of the current ultrafast spectroscopy studies of these novel molecules to their roles in photocatalysis will be discussed.

  19. Near-Edge X-ray Absorption Fine Structure Spectroscopy of Diamondoid Thiol Monolayers on Gold

    Energy Technology Data Exchange (ETDEWEB)

    Willey, T M; Fabbri, J; Lee, J I; Schreiner, P; Fokin, A A; Tkachenko, B A; Fokina, N A; Dahl, J; Carlson, B; Vance, A L; Yang, W; Terminello, L J; van Buuren, T; Melosh, N

    2007-11-27

    Diamondoids, hydrocarbon molecules with cubic-diamond-cage structures, have unique properties with potential value for nanotechnology. The availability and ability to selectively functionalize this special class of nanodiamond materials opens new possibilities for surface-modification, for high-efficiency field emitters in molecular electronics, as seed crystals for diamond growth, or as robust mechanical coatings. The properties of self-assembled monolayers (SAMs) of diamondoids are thus of fundamental interest for a variety of emerging applications. This paper presents the effects of thiol substitution position and polymantane order on diamondoid SAMs on gold using near-edge X-ray absorption fine structure spectroscopy (NEXAFS) and X-ray photoelectron spectroscopy (XPS). A framework to determine both molecular tilt and twist through NEXAFS is presented and reveals highly ordered diamondoid SAMs, with the molecular orientation controlled by the thiol location. C 1s and S 2p binding energies are lower in adamantane thiol than alkane thiols on gold by 0.67 {+-} 0.05 eV and 0.16 {+-} 0.04 eV respectively. These binding energies vary with diamondoid monolayer structure and thiol substitution position, consistent with different amounts of steric strain and electronic interaction with the substrate. This work demonstrates control over the assembly, in particular the orientational and electronic structure, providing a flexible design of surface properties with this exciting new class of diamond clusters.

  20. Evaluation of self-absorption coefficients of aluminum emission lines in laser-induced breakdown spectroscopy measurements

    International Nuclear Information System (INIS)

    El Sherbini, A.M.; El Sherbini, Th.M.; Hegazy, H.; Cristoforetti, G.; Legnaioli, S.; Palleschi, V.; Pardini, L.; Salvetti, A.; Tognoni, E.

    2005-01-01

    In quantitative Laser Induced Breakdown Spectroscopy (LIBS) measurements it is essential to account for the effect of self-absorption on the emission lines intensity. In order to quantify this effect, in this paper we propose a simple method for evaluating the ratio between the actual measured line intensity and the intensity expected in absence of self-absorption and, if necessary, correcting the effect of self-absorption on line intensity. The method, based on a homogeneous plasma model, is applicable when the plasma electron density is known and in particular to lines whose Stark broadening parameter is available

  1. Distinct local structure of nanoparticles and nanowires of V2O5 probed by x-ray absorption spectroscopy

    Science.gov (United States)

    Joseph, B.; Iadecola, A.; Maugeri, L.; Bendele, M.; Okubo, M.; Li, H.; Zhou, H.; Mizokawa, T.; Saini, N. L.

    2013-12-01

    We have used V K-edge x-ray absorption spectroscopy to study local structures of bulk, nanoparticles and nanowires of V2O5. The extended x-ray absorption fine structure measurements show different local displacements in the three morphologically different V2O5 samples. It is found that the nanowires have a significantly ordered chain structure in comparison to the V2O5 bulk. In contrast, nanoparticles have larger interlayer disorder. The x-ray absorption near-edge structure spectra show different electronic structure that appears to be related with the local atomic disorder in the three V2O5 samples.

  2. X-ray absorption spectroscopy in the keV range with laser generated high harmonic radiation

    International Nuclear Information System (INIS)

    Seres, Enikoe; Seres, Jozsef; Spielmann, Christian

    2006-01-01

    By irradiating He and Ne atoms with 3 mJ, 12 fs, near infrared laser pulses from a tabletop laser system, the authors generated spatially and temporally coherent x rays up to a photon energy of 3.5 keV. With this source it is possible to use high-harmonic radiation for x-ray absorption spectroscopy in the keV range. They were able to clearly resolve the L absorption edges of titanium and copper and the K edges of aluminum and silicon. From the fine structure of the x-ray absorption they estimated the interatomic distances

  3. O2 absorption cross sections /187-225 nm/ from stratospheric solar flux measurements

    Science.gov (United States)

    Herman, J. R.; Mentall, J. E.

    1982-10-01

    The absorption cross sections of molecular oxygen are calculated in the wavelength range from 187 to 230 nm from solar flux measurements obtained within the stratosphere. Within the Herzberg continuum wavelength region the molecular oxygen cross sections are found to be about 30% smaller than the laboratory results of Shardanand and Rao (1977) from 200 to 210 nm and about 50% smaller than those of Hasson and Nicholls (1971). At wavelengths longer than 210 nm the cross sections agree with those of Shardanand and Rao. The effective absorption cross sections of O2 in the Schumann-Runge band region from 187 to 200 nm are calculated and compared to the empirical fit given by Allen and Frederick (1982). The calculated cross sections indicate that the transmissivity of the atmosphere may be underestimated by the use of the Allen and Frederic cross sections between 195 and 200 nm. The ozone column content between 30 and 40 km and the relative ozone cross sections are determined from the same solar flux data set.

  4. Absorption Spectroscopy in Hollow-Glass Waveguides Using Infrared Diode Lasers[4817-25

    International Nuclear Information System (INIS)

    Blake, Thomas A.; Kelly, James F.; Stewart, Timothy L.; Hartman, John S.; Sharpe, Steven W.; Sams, Robert L.; Alan Fried

    2002-01-01

    Near- and mid-infrared diode lasers combined with flexible, hollow waveguides hold the promise of light weight, field portable, fast response gas sensors. The advantages of using the waveguides compared to White or Herriott multireflection cells include a small gas volume, a high photon fill factor in the waveguide, which increases molecule-light interactions, and reduction or elimination of optical fringing, which usually sets the practical limit of detectivity in absorption spectroscopy. Though hollow waveguides have been commercially available for several years, relatively few results have been reported in the literature. We present here results from our laboratory where we have injected infrared laser light into straight and coiled lengths of hollow waveguides and performed direct and wavelength modulated absorption spectroscopy on nitrous oxide, ethylene, and nitric oxide. Using a 1 mm bore, 3 meter long coiled waveguide coated for the near infrared, nitrous oxide transitions near 6595 cm-1 were observed under flowing conditions. Signal-to-noise ratios on the order of 1500:1 with RMS noise equal to 2 X 10-5 were measured. In the mid-infrared light from either a 10.1 or 5.3 micron lead salt diode laser was injected into a three meter length of 1 mm bore hollow waveguide coated for the mid-infrared. The waveguide was coiled with one loop at a diameter of 52 cm. Ethylene transitions were observed in the vicinity of 985 cm-1 with a static fill of 0.2 Torr of pure ethylene in the waveguide and nitric oxide transitions were observed in the vicinity of 1906 cm-1 using either a flow or a static fill of 1 ppm NO in nitrogen. In direct absorption the NO transitions are observed to have a signal-to-noise of approximately 5:1 for transitions with absorbances on the order of 10-3. Using wavelength modulated techniques the signal-to-noise ratio improves at least an order of magnitude. These encouraging results indicate that waveguides can be used for in situ gas monitoring

  5. Imaging spectroscopy of solar radio burst fine structures.

    Science.gov (United States)

    Kontar, E P; Yu, S; Kuznetsov, A A; Emslie, A G; Alcock, B; Jeffrey, N L S; Melnik, V N; Bian, N H; Subramanian, P

    2017-11-15

    Solar radio observations provide a unique diagnostic of the outer solar atmosphere. However, the inhomogeneous turbulent corona strongly affects the propagation of the emitted radio waves, so decoupling the intrinsic properties of the emitting source from the effects of radio wave propagation has long been a major challenge in solar physics. Here we report quantitative spatial and frequency characterization of solar radio burst fine structures observed with the Low Frequency Array, an instrument with high-time resolution that also permits imaging at scales much shorter than those corresponding to radio wave propagation in the corona. The observations demonstrate that radio wave propagation effects, and not the properties of the intrinsic emission source, dominate the observed spatial characteristics of radio burst images. These results permit more accurate estimates of source brightness temperatures, and open opportunities for quantitative study of the mechanisms that create the turbulent coronal medium through which the emitted radiation propagates.

  6. Characterising legacy spent nuclear fuel pond materials using microfocus X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Bower, W.R.; Morris, K.; Mosselmans, J.F.W.; Thompson, O.R.; Banford, A.W.; Law, K.; Pattrick, R.A.D.

    2016-01-01

    Highlights: • A sample from a spent fuel pond wall has been analysed via X-ray spectroscopy. • Autoradiography shows a patchy distribution of radioactivity on the core face. • μXAS across a ‘hot spot’ showed Sr associates with the TiO 2 pigment in the paint. • Original concrete coatings prove effective at limiting radionuclide migration. • Sorption studies show Sr immobilisation by the concrete and Cs by aggregate clasts. - Abstract: Analysis of a radioactive, coated concrete core from the decommissioned, spent nuclear fuel cooling pond at the Hunterston-A nuclear site (UK) has provided a unique opportunity to study radionuclides within a real-world system. The core, obtained from a dividing wall and sampled at the fill level of the pond, exhibited radioactivity (dominantly 137 Cs and 90 Sr) heterogeneously distributed across both painted faces. Chemical analysis of the core was undertaken using microfocus spectroscopy at Diamond Light Source, UK. Mapping of Sr across the surface coatings using microfocus X-ray fluorescence (μXRF) combined with X-ray absorption spectroscopy showed that Sr was bound to TiO 2 particles in the paint layers, suggesting an association between TiO 2 and radiostrontium. Stable Sr and Cs sorption experiments using concrete coupons were also undertaken to assess their interactions with the bulk concrete in case of a breach in the coating layers. μXRF and scanning electron microscopy showed that Sr was immobilized by the cement phases, whilst at the elevated experimental concentrations, Cs was associated with clay minerals in the aggregates. This study provides a crucial insight into poorly understood infrastructural contamination in complex systems and is directly applicable to the UK’s nuclear decommissioning efforts.

  7. Characterising legacy spent nuclear fuel pond materials using microfocus X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bower, W.R. [Research Centre for Radwaste Disposal, School of Earth and Environmental Sciences, The University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom); National Nuclear Laboratory, Chadwick House, Warrington Road, Birchwood Park, Warrington, WA3 6AE (United Kingdom); Centre for Radiochemistry Research, Chemistry Building, The University of Manchester, Brunswick Street, Manchester M13 9PL (United Kingdom); Morris, K. [Research Centre for Radwaste Disposal, School of Earth and Environmental Sciences, The University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom); Mosselmans, J.F.W. [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE (United Kingdom); Thompson, O.R. [National Nuclear Laboratory, Chadwick House, Warrington Road, Birchwood Park, Warrington, WA3 6AE (United Kingdom); Banford, A.W. [National Nuclear Laboratory, Chadwick House, Warrington Road, Birchwood Park, Warrington, WA3 6AE (United Kingdom); School of Chemical Engineering and Analytical Science, The University of Manchester, Oxford Road, Manchester, M13 9PL (United Kingdom); Law, K. [Centre for Radiochemistry Research, Chemistry Building, The University of Manchester, Brunswick Street, Manchester M13 9PL (United Kingdom); Pattrick, R.A.D., E-mail: richard.pattrick@manchester.ac.uk [Research Centre for Radwaste Disposal, School of Earth and Environmental Sciences, The University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom)

    2016-11-05

    Highlights: • A sample from a spent fuel pond wall has been analysed via X-ray spectroscopy. • Autoradiography shows a patchy distribution of radioactivity on the core face. • μXAS across a ‘hot spot’ showed Sr associates with the TiO{sub 2} pigment in the paint. • Original concrete coatings prove effective at limiting radionuclide migration. • Sorption studies show Sr immobilisation by the concrete and Cs by aggregate clasts. - Abstract: Analysis of a radioactive, coated concrete core from the decommissioned, spent nuclear fuel cooling pond at the Hunterston-A nuclear site (UK) has provided a unique opportunity to study radionuclides within a real-world system. The core, obtained from a dividing wall and sampled at the fill level of the pond, exhibited radioactivity (dominantly {sup 137}Cs and {sup 90}Sr) heterogeneously distributed across both painted faces. Chemical analysis of the core was undertaken using microfocus spectroscopy at Diamond Light Source, UK. Mapping of Sr across the surface coatings using microfocus X-ray fluorescence (μXRF) combined with X-ray absorption spectroscopy showed that Sr was bound to TiO{sub 2} particles in the paint layers, suggesting an association between TiO{sub 2} and radiostrontium. Stable Sr and Cs sorption experiments using concrete coupons were also undertaken to assess their interactions with the bulk concrete in case of a breach in the coating layers. μXRF and scanning electron microscopy showed that Sr was immobilized by the cement phases, whilst at the elevated experimental concentrations, Cs was associated with clay minerals in the aggregates. This study provides a crucial insight into poorly understood infrastructural contamination in complex systems and is directly applicable to the UK’s nuclear decommissioning efforts.

  8. Understanding charge carrier relaxation processes in terbium arsenide nanoparticles using transient absorption spectroscopy

    Science.gov (United States)

    Vanderhoef, Laura R.

    Erbium arsenide nanoparticles epitaxially grown within III-V semiconductors have been shown to improve the performance of devices for applications ranging from thermoelectrics to THz pulse generation. The small size of rare-earth nanoparticles suggests that interesting electronic properties might emerge as a result of both spatial confinement and surface states. However, ErAs nanoparticles do not exhibit any signs of quantum confinement or an emergent bandgap, and these experimental observations are understood from theory. The incorporation of other rare-earth monopnictide nanoparticles into III-V hosts is a likely path to engineering carrier excitation, relaxation and transport dynamics for optoelectronic device applications. However, the electronic structure of these other rare-earth monopnictide nanoparticles remains poorly understood. The objective of this research is to explore the electronic structure and optical properties of III-V materials containing novel rare-earth monopnictides. We use ultrafast pump-probe spectroscopy to investigate the electronic structure of TbAs nanoparticles in III-V hosts. We start with TbAs:GaAs, which was expected to be similar to ErAs:GaAs. We study the dynamics of carrier relaxation into the TbAs states using optical pump terahertz probe transient absorption spectroscopy. By analyzing how the carrier relaxation rates depend on pump fluence and sample temperature, we conclude that the TbAs states are saturable. Saturable traps suggest the existence of a bandgap for TbAs nanoparticles, in sharp contrast with previous results for ErAs. We then apply the same experimental technique to two samples of TbAs nanoparticles in InGaAs with different concentrations of TbAs. We observe similar relaxation dynamics associated with trap saturation, though the ability to resolve these processes is contingent upon a high enough TbAs concentration in the sample. We have also constructed an optical pump optical probe transient absorption

  9. Validation of visible/near-IR atmospheric absorption and solar emission spectroscopic models at 1 cm-1 resolution

    Science.gov (United States)

    Lubin, Dan; Vogelmann, Andrew; Lehr, Pamela J.; Kressin, Ann; Ehramjian, James; Ramanathan, V.

    2000-09-01

    A Fourier transform infrared (FTIR) spectrometer, operating at 1 cm-1 resolution between 9000 and 24,669 cm-1 (0.405-1.111 μm) has been used to check the spectral composition of databases that form the basis for most atmospheric absorption parameterizations used in climate models, remote sensing, and other radiative transfer simulations. The spectrometer, operating near sea level under clear skies, obtained relative atmospheric transmission measurements of the direct solar beam by means of a heliostat. The spectroscopic data were compared with a line-by-line radiative transfer model (LBLRTM) calculation of direct solar beam flux, which used a input data a monochromatic model extraterrestrial solar flux spectrum currently in common use. This intercomparison revealed that the extraterrestrial solar flux spectrum contains 266 solar absorption features that do not appear in the data, resulting in an excess of approximately 1.92 W m-2 in the model's solar constant. The intercomparison also revealed 97 absorption features in the data that do not appear in the HITRAN-96 database as used by LBLRTM, resulting in a model underestimate of shortwave absorption of ˜0.23 W m-2 for a solar zenith angle of 42°. These small discrepancies revealed by the intercomparison indicate that current extraterrestrial solar irradiance models and spectroscopic databases used by shortwave atmospheric radiative transfer models are nearly entirely complete for purposes of atmospheric energy budget calculation. Thus clear or cloudy sky `excess absorption' is unlikely to be related to an incomplete identification of atmospheric absorbing gases and their spectroscopic features, at 1 cm-1 resolution, for a clean troposphere of normal composition.

  10. [In-situ monitoring algorithm of gases poisonous elements concentration with ultraviolet optical absorption spectroscopy based on recursion iterative method].

    Science.gov (United States)

    Wang, Hui-feng; Jiang, Xu-qian

    2012-01-01

    The key and challenge problem of in-situ monitoring poisonous elements of gases is how to separate the various gases absorption signal from mixed gases absorption spectroscopy and compute it's accuracy concentration? Here we present a new algorithms in return recursion iteration based on Lambert-Beer principle. In the algorithms, recurred by the character of absorption peak of various gases in the band of 190-290 nm UV rays continuous spectroscopy and the character of twin element fold for absorbance are used. Firstly, the authors suppose that there is no absorption for others gases in the character absorption band for a certain gas, the authors can inference the initial concentration of the gas. Then the authors switch to another character spectroscopy, and put the photons that gases absorption out of the total number of absorbed photons that are measured. So we could get the initial concentration of another gas. By analogy the authros can get the initial concentration of all kinds of other poisonous elements. Then come back to the character spectroscopy of the first gas, the authors can get a new concentration of the first gas from the difference between the total number of absorbed photons and the photons that other gases absorption. By analogy the authors can get the iterative concentration of other gases, by irterating this process repeatly for some times until the measurement error of the adjacent gas concentration is smaller than a certain numerical value. Finally the authors can get the real and accurate concentration of all kinds of gases. Experiment shows that the authors can get the accurate concentration of all kinds of gases with the algorithm. The accuracy can be within 2%, and at the same time, it is easy enough to satisfy the necessity of real-time requirement. In addition it could be used to measure the concentration of many kinds of gas at a time. It is robust and suitable to be taken into practice.

  11. MEASUREMENTS OF ABSORPTION, EMISSIVITY REDUCTION, AND LOCAL SUPPRESSION OF SOLAR ACOUSTIC WAVES IN SUNSPOTS

    International Nuclear Information System (INIS)

    Chou, D.-Y.; Liang, Z.-C.; Yang, M.-H.; Zhao Hui; Sun, M.-T.

    2009-01-01

    The power of solar acoustic waves in magnetic regions is lower relative to the quiet Sun. Absorption, emissivity reduction, and local suppression of acoustic waves contribute to the observed power reduction in magnetic regions. We propose a model for the energy budget of acoustic waves propagating through a sunspot in terms of the coefficients of absorption, emissivity reduction, and local suppression of the sunspot. Using the property that the waves emitted along the wave path between two points have no correlation with the signal at the starting point, we can separate the effects of these three mechanisms. Applying this method to helioseismic data filtered with direction and phase-velocity filters, we measure the fraction of the contribution of each mechanism to the power deficit in the umbra of the leading sunspot of NOAA 9057. The contribution from absorption is 23.3 ± 1.3%, emissivity reduction 8.2 ± 1.4%, and local suppression 68.5 ± 1.5%, for a wave packet corresponding to a phase velocity of 6.98 x 10 -5 rad s -1 .

  12. Retrieval interval mapping, a tool to optimize the spectral retrieval range in differential optical absorption spectroscopy

    Science.gov (United States)

    Vogel, L.; Sihler, H.; Lampel, J.; Wagner, T.; Platt, U.

    2012-06-01

    Remote sensing via differential optical absorption spectroscopy (DOAS) has become a standard technique to identify and quantify trace gases in the atmosphere. The technique is applied in a variety of configurations, commonly classified into active and passive instruments using artificial and natural light sources, respectively. Platforms range from ground based to satellite instruments and trace-gases are studied in all kinds of different environments. Due to the wide range of measurement conditions, atmospheric compositions and instruments used, a specific challenge of a DOAS retrieval is to optimize the parameters for each specific case and particular trace gas of interest. This becomes especially important when measuring close to the detection limit. A well chosen evaluation wavelength range is crucial to the DOAS technique. It should encompass strong absorption bands of the trace gas of interest in order to maximize the sensitivity of the retrieval, while at the same time minimizing absorption structures of other trace gases and thus potential interferences. Also, instrumental limitations and wavelength depending sources of errors (e.g. insufficient corrections for the Ring effect and cross correlations between trace gas cross sections) need to be taken into account. Most often, not all of these requirements can be fulfilled simultaneously and a compromise needs to be found depending on the conditions at hand. Although for many trace gases the overall dependence of common DOAS retrieval on the evaluation wavelength interval is known, a systematic approach to find the optimal retrieval wavelength range and qualitative assessment is missing. Here we present a novel tool to determine the optimal evaluation wavelength range. It is based on mapping retrieved values in the retrieval wavelength space and thus visualize the consequence of different choices of retrieval spectral ranges, e.g. caused by slightly erroneous absorption cross sections, cross correlations and

  13. Investigating the collector efficiency of silver nanofluids based direct absorption solar collectors

    International Nuclear Information System (INIS)

    Chen, Meijie; He, Yurong; Zhu, Jiaqi; Wen, Dongsheng

    2016-01-01

    Highlights: • An analysis coupled with Radiation transfer, Maxwell and Energy equation is developed. • Plasmonic Au and Ag nanofluids show better photo-thermal conversion properties. • Collector height and particle concentration exist optimum solutions for efficiency. - Abstract: A one-dimensional transient heat transfer analysis was carried out to analyze the effects of the Nanoparticle (NP) volume fraction, collector height, irradiation time, solar flux, and NP material on the collector efficiency. The numerical results were compared with the experimental results obtained by silver nanofluids to validate the model, and good agreement was obtained. The numerical results show that the collector efficiency increases as the collector height and NP volume fraction increase and then reaches a maximum value. An optimum collector height (∼10 mm) and particle concentration (∼0.03%) achieving a collector efficiency of 90% of the maximum efficiency can be obtained under the conditions used in the simulation. However, the collector efficiency decreases as the irradiation time increases owing to the increased heat loss. A high solar flux is desirable to maintain a high efficiency over a wide temperature range, which is beneficial for subsequent energy utilization. The modeling results also show silver and gold nanofluids obtain higher photothermal conversion efficiencies than the titanium dioxide nanofluid because their absorption spectra are similar to the solar radiation spectrum.

  14. Heating of the solar corona by the resonant absorption of Alfven waves

    International Nuclear Information System (INIS)

    Davila, J.M.

    1987-01-01

    An improved method for calculating the resonance absorption heating rate is discussed and the results are compared with observations in the solar corona. To accomplish this, the wave equation for a dissipative, compressible plasma is derived from the linearized magnetohydrodynamic equations for a plasma with transverse Alfven speed gradients. For parameters representative of the solar corona, it is found that a two-scale description of the wave motion is appropriate. The large-scale motion, which can be approximated as nearly ideal, has a scale which is on the order of the width of the loop. The small-scale wave, however, has a transverse scale much smaller than the width of the loop, with a width of about 0.3-250 km, and is highly dissipative. These two wave motions are coupled in a narrow resonance region in the loop where the global wave frequency equals the local Alfven wave frequency. Formally, this coupling comes about from using the method of matched asymptotic expansions to match the inner and outer (small and large scale) solutions. The resultant heating rate can be calculated from either of these solutions. A formula derived using the outer (ideal) solution is presented, and shown to be consistent with observations of heating and line broadening in the solar corona. 34 references

  15. Spectroscopy of Technological Defects in Si Solar Cells by Analysis of Temperature Dependent Generation Currents

    Directory of Open Access Journals (Sweden)

    Jevgenij PAVLOV

    2014-09-01

    Full Text Available The efficiency of solar cells considerably depends on the technological defects introduced by the formation of junctions, passivation layers and electrodes. Identification of these defects present in the high conductivity base layer of modern solar cells by usage of the standard techniques, such as capacitance deep level spectroscopy, is restricted by extremely small size of samples with inherent enhanced leakage current on sample boundaries. Therefore, it is important to develop the alternative methods for the defect spectroscopy in the high conductivity junction structures, to directly control a relative low concentration of the technological defects. In this work, the spectroscopy of deep traps has been performed by combining the temperature scans of the thermal generation currents extracted from barrier capacitance charging transients and capacitance deep level transient spectroscopy techniques. The dominant carrier traps ascribed to the Cu and Ni impurities were revealed. DOI: http://dx.doi.org/10.5755/j01.ms.20.3.5194

  16. A Simplified Digestion Protocol for the Analysis of Hg in Fish by Cold Vapor Atomic Absorption Spectroscopy

    Science.gov (United States)

    Kristian, Kathleen E.; Friedbauer, Scott; Kabashi, Donika; Ferencz, Kristen M.; Barajas, Jennifer C.; O'Brien, Kelly

    2015-01-01

    Analysis of mercury in fish is an interesting problem with the potential to motivate students in chemistry laboratory courses. The recommended method for mercury analysis in fish is cold vapor atomic absorption spectroscopy (CVAAS), which requires homogeneous analyte solutions, typically prepared by acid digestion. Previously published digestion…

  17. Two-Dimensional UV Absorption Correlation Spectroscopy as a Method for the Detection of Thiamethoxam Residue in Tea

    Science.gov (United States)

    Zhang, J.; Zhao, Zh.; Wang, L.; Zhu, X.; Shen, L.; Yu, Y.

    2015-05-01

    Two-dimensional correlation spectroscopy (2D-COS) combined with UV absorption spectroscopy was evaluated as a technique for the identification of spectral regions associated with the residues of thiamethoxam in tea. There is only one absorption peak at 275 nm in the absorption spectrum of a mixture of thiamethoxam and tea, which is the absorption peak of tea. Based on 2D-COS, the absorption peak of thiamethoxam at 250 nm is extracted from the UV spectra of the mixture. To determine the residue of thiamethoxam in tea, 250 nm is selected as the measured wavelength, at which the fitting result is as follows: the residual sum of squares is 0.01375, standard deviation R2 is 0.99068, and F value is 426. Statistical analysis shows that there is a significant linear relationship between the concentration of thiamethoxam in tea and the absorbance at 250 nm in the UV spectra of the mixture. Moreover, the average prediction error is 0.0033 and the prediction variance is 0.1654, indicating good predictive result. Thus, the UV absorption spectrum can be used as a measurement method for rapid detection of thiamethoxam residues in tea.

  18. Investigating several ZrN plasmonic nanostructures and their effect on the absorption of organic solar cells

    Science.gov (United States)

    Magdi, Sara; Swillam, Mohamed A.

    2017-09-01

    Broadband absorption enhancement is obtained in organic solar cells using zirconium nitride (ZrN) plasmonic nanostructures. Due to the thickness limitations imposed on organic solar cells, their absorption efficiency is limited. Plasmonic nanostructures have the ability to increase their optical efficiency by increasing the light path length inside the active material. Here, refractory plasmonics, a new type of plasmonic nanostructures, is used in organic solar cells instead of traditional metal plasmonics. ZrN, as an example of refractory plasmonics, has a high localized surface plasmon resonance quality factor in the visible range while being cheap, abundant, and C-MOS compatible. Here, several ZrN plasmonic nanostructures are studied including ZrN nanospheres, nanocubes, and nanoshells. Their Mie scattering and absorption efficiencies in a polymer environment are calculated. In addition, the effect of their incorporation on the absorbed power and short circuit current of organic solar cell is analyzed. ZrN nanodisks are also studied in different locations inside the solar cell with the best performance found for nanodisks placed at the interface between the active and the buffer layer. The highest absorption enhancement reported here is obtained when ZrN cubical nanoshells are added. A 34.7% increase in short circuit current is calculated for this structure.

  19. The Lowest Triplet of Tetracyanoquinodimethane via UV-vis Absorption Spectroscopy with Br-Containing Solvents.

    Science.gov (United States)

    Khvostenko, Olga G; Kinzyabulatov, Renat R; Khatymova, Laysan Z; Tseplin, Evgeniy E

    2017-10-05

    This study was undertaken to find the previously unknown lowest triplet of the isolated molecule of tetracyanoquinodimethane (TCNQ), which is a widely used organic semiconductor. The problem is topical because the triplet excitation of this compound is involved in some processes which occur in electronic devices incorporating TCNQ and its derivatives, and information on the TCNQ triplet is needed for better understanding of these processes. The lowest triplet of TCNQ was obtained at 1.96 eV using UV-vis absorption spectroscopy with Br-containing solvents. Production of the triplet band with sufficient intensity in the spectra was provided by the capacity of the Br atom to augment the triplet excitation and through using a 100 mm cuvette. The assignment of the corresponding spectral band to the triplet transition was made by observation that this band appeared only in the spectra recorded in Br-containing solvents but not in spectra recorded in other solvents. Additional support for the triplet assignment came from the overall UV-vis absorption spectra of TCNQ recorded in various solvents, using a 10 mm cuvette, in the 1.38-6.5 eV energy range. Singlet transitions of the neutral TCNQ o molecule and doublet transitions of the TCNQ ¯ negative ion were identified in these overall spectra and were assigned with TD B3LYP/6-31G calculations. Determination of the lowest triplet of TCNQ attained in this work may be useful for theoretical studies and practical applications of this important compound.

  20. X-ray absorption spectroscopy in biological systems. Opportunities and limitations

    Energy Technology Data Exchange (ETDEWEB)

    Bovenkamp, Gudrun Lisa

    2013-05-15

    X-ray absorption spectroscopy has become more important for applications in the material sciences, geology, environmental science and biology, specifically in the field of molecular biology. The scope of this thesis is to add more experimental evidence in order to show how applicable X-ray absorption near edge structure (XANES) is to biology. Two biological systems were investigated, at the molecular level, lead uptake in plants and the effect of silver on bacteria. This investigation also included an analysis of the sensitivity of Pb L{sub 3}- and Ag L{sub 3}-XANES spectra with regard to their chemical environment. It was shown that Pb L{sub 3}- and Ag L{sub 3}-XANES spectra are sensitive to an environment with at least differences in the second coordination shell. The non-destructive and element specific properties of XANES are the key advantages that were very important for this investigation. However, in both projects the adequate selection of reference compounds, which required in some cases a chemical synthesis, was the critical factor to determine the chemical speciation and, finally, possible uptake and storage mechanisms for plants and antibacterial mechanisms of silver. The chemical environment of Pb in roots and leaves of plants from four different plant families and a lichen from a former lead mining site in the Eifel mountains in Germany was determined using both solid compounds and aqueous solutions of different ionic strength, which simulate the plant environment. The results can be interpreted in such a way that lead is sorbed on the surface of cell walls. Silver bonding as reaction with Staphylococcus aureus, Listeria monocytogenes, and Escherichia coli bacteria was determined using inorganic silver compounds and synthesized silver amino acids. Silver binds to sulfur, amine and carboxyl groups in amino acids.

  1. Ultrafast Excited State Relaxation of a Metalloporphyrin Revealed by Femtosecond X-ray Absorption Spectroscopy.

    Science.gov (United States)

    Shelby, Megan L; Lestrange, Patrick J; Jackson, Nicholas E; Haldrup, Kristoffer; Mara, Michael W; Stickrath, Andrew B; Zhu, Diling; Lemke, Henrik T; Chollet, Matthieu; Hoffman, Brian M; Li, Xiaosong; Chen, Lin X

    2016-07-20

    Photoexcited Nickel(II) tetramesitylporphyrin (NiTMP), like many open-shell metalloporphyrins, relaxes rapidly through multiple electronic states following an initial porphyrin-based excitation, some involving metal centered electronic configuration changes that could be harnessed catalytically before excited state relaxation. While a NiTMP excited state present at 100 ps was previously identified by X-ray transient absorption (XTA) spectroscopy at a synchrotron source as a relaxed (d,d) state, the lowest energy excited state (J. Am. Chem. Soc., 2007, 129, 9616 and Chem. Sci., 2010, 1, 642), structural dynamics before thermalization were not resolved due to the ∼100 ps duration of the available X-ray probe pulse. Using the femtosecond (fs) X-ray pulses of the Linac Coherent Light Source (LCLS), the Ni center electronic configuration from the initial excited state to the relaxed (d,d) state has been obtained via ultrafast Ni K-edge XANES (X-ray absorption near edge structure) on a time scale from hundreds of femtoseconds to 100 ps. This enabled the identification of a short-lived Ni(I) species aided by time-dependent density functional theory (TDDFT) methods. Computed electronic and nuclear structure for critical excited electronic states in the relaxation pathway characterize the dependence of the complex's geometry on the electron occupation of the 3d orbitals. Calculated XANES transitions for these excited states assign a short-lived transient signal to the spectroscopic signature of the Ni(I) species, resulting from intramolecular charge transfer on a time scale that has eluded previous synchrotron studies. These combined results enable us to examine the excited state structural dynamics of NiTMP prior to thermal relaxation and to capture intermediates of potential photocatalytic significance.

  2. Incorporation of arsenic in mammal bone: X-ray absorption spectroscopy

    Science.gov (United States)

    Kretschmer, X.; Pingitore, N. E.; Cruz-Jimenez, G.

    2002-12-01

    X-ray absorption spectroscopy (XAS) of the distal tibia of a modern deer, Odocoileus virginianus, revealed that the energy position of the As K edge matched that of a reference arsenic(V) model compound. Comparison of the x-ray absorption near edge structure (XANES) of the deer spectrum to the spectra of model As compounds indicated a close match to arsenate(V), e.g., zinc orthoarsenate(5). This indicates that the nearest-neighbor shell of the arsenic in the bone consists of four oxygens in the tetrahedral arrangement typical of arsenic(V) oxysalts. The XANES analysis demonstrates that the arsenic in the deer bone is not associated with an organic compound as a result of methylation. This suggests that the arsenic is associated with the mineral fraction of the bone, most likely with As substituting for P at the latter's structural site in the hydroxyapatite. The XAS data for the deer bone were very noisy due to the low level of arsenic present, just over 1 ppm.. A total of 18 scans, taking nearly a full 8-hour beam shift, were averaged to obtain the spectrum studied. It is not clear that the second neighbor shell can be characterized sufficiently from these data to confirm that As substitutes for P in hydroxyapatite. We conducted our XAS experiments on beam line 4-3 at the Stanford Synchrotron Radiation Laboratory. Data were collected in the fluorescence mode, using a solid state, 13-element Ge-detector. The energy reference was As(0) metal foil run parasitically in transmission mode during collection of the bone spectra. The edge shift seen in the experimental and As(V) model compound relative to the energy position of the arsenic(0) foil is consistent with the additional energy required to photoeject the 1-s electron of As(V), relative to that required for As(0). Arsenic content of the deer bone was determined by inductively coupled plasma mass spectrometry.

  3. X-ray absorption spectroscopy in biological systems. Opportunities and limitations

    International Nuclear Information System (INIS)

    Bovenkamp, Gudrun Lisa

    2013-05-01

    X-ray absorption spectroscopy has become more important for applications in the material sciences, geology, environmental science and biology, specifically in the field of molecular biology. The scope of this thesis is to add more experimental evidence in order to show how applicable X-ray absorption near edge structure (XANES) is to biology. Two biological systems were investigated, at the molecular level, lead uptake in plants and the effect of silver on bacteria. This investigation also included an analysis of the sensitivity of Pb L 3 - and Ag L 3 -XANES spectra with regard to their chemical environment. It was shown that Pb L 3 - and Ag L 3 -XANES spectra are sensitive to an environment with at least differences in the second coordination shell. The non-destructive and element specific properties of XANES are the key advantages that were very important for this investigation. However, in both projects the adequate selection of reference compounds, which required in some cases a chemical synthesis, was the critical factor to determine the chemical speciation and, finally, possible uptake and storage mechanisms for plants and antibacterial mechanisms of silver. The chemical environment of Pb in roots and leaves of plants from four different plant families and a lichen from a former lead mining site in the Eifel mountains in Germany was determined using both solid compounds and aqueous solutions of different ionic strength, which simulate the plant environment. The results can be interpreted in such a way that lead is sorbed on the surface of cell walls. Silver bonding as reaction with Staphylococcus aureus, Listeria monocytogenes, and Escherichia coli bacteria was determined using inorganic silver compounds and synthesized silver amino acids. Silver binds to sulfur, amine and carboxyl groups in amino acids.

  4. Time-resolved pump-probe X-ray absorption fine structure spectroscopy of Gaq3

    International Nuclear Information System (INIS)

    Dicke, Benjamin

    2013-01-01

    Gallium(tris-8-hydroxyquinoline) (Gaq 3 ) belongs to a class of metal organic compounds, used as electron transport layer and emissive layer in organic light emitting diodes. Many research activities have concentrated on the optical and electronic properties, especially of the homologue molecule aluminum(tris-8-hydroxyquinoline) (Alq 3 ). Knowledge of the first excited state S 1 structure of these molecules could provide deeper insight into the processes involved into the operation of electronic devices, such as OLEDs and, hence, it could further improve their efficiency and optical properties. Until now the excited state structure could not be determined experimentally. Most of the information about this structure mainly arises from theoretical calculations. X-ray absorption fine structure (XAFS) spectroscopy is a well developed technique to determine both, the electronic and the geometric properties of a sample. The connection of ultrashort pulsed X-ray sources with a pulsed laser system offers the possibility to use XAFS as a tool for studying the transient changes of a sample induced by a laser pulse. In the framework of this thesis a new setup for time-resolved pump-probe X-ray absorption spectroscopy at PETRA III beamline P11 was developed for measuring samples in liquid form. In this setup the sample is pumped into its photo-excited state by a femtosecond laser pump pulse with 343 nm wavelength and after a certain time delay probed by an X-ray probe pulse. In this way the first excited singlet state S 1 of Gaq 3 dissolved in benzyl alcohol was analyzed. A structural model for the excited state structure of the Gaq 3 molecule based on the several times reproduced results of the XAFS experiments is proposed. According to this model it was found that the Ga-N A bond length is elongated, while the Ga-O A bond length is shortened upon photoexcitation. The dynamics of the structural changes were not the focus of this thesis. Nevertheless the excited state lifetime

  5. Microbeam x-ray absorption spectroscopy study of chromium in large-grain uranium dioxide fuel

    Science.gov (United States)

    Mieszczynski, C.; Kuri, G.; Bertsch, J.; Martin, M.; Borca, C. N.; Delafoy, Ch; Simoni, E.

    2014-09-01

    Synchrotron-based microprobe x-ray absorption spectroscopy (XAS) has been used to study the local atomic structure of chromium in chromia-doped uranium dioxide (UO2) grains. The specimens investigated were a commercial grade chromia-doped UO2 fresh fuel pellet, and materials from a spent fuel pellet of the same batch, irradiated with an average burnup of ~40 MW d kg-1. Uranium L3-edge and chromium K-edge XAS have been measured, and the structural environments of central uranium and chromium atoms have been elucidated. The Fourier transform of uranium L3-edge extended x-ray absorption fine structure shows two well-defined peaks of U-O and U-U bonds at average distances of 2.36 and 3.83 Å. Their coordination numbers are determined as 8 and 11, respectively. The chromium Fourier transform extended x-ray absorption fine structure of the pristine UO2 matrix shows similar structural features with the corresponding spectrum of the irradiated spent fuel, indicative of analogous chromium environments in the two samples studied. From the chromium XAS experimental data, detectable next neighbor atoms are oxygen and uranium of the cation-substituted UO2 lattice, and two distinct subshells of chromium and oxygen neighbors, possibly because of undissolved chromia particles present in the doped fuels. Curve-fitting analyses using theoretical amplitude and phase-shift functions of the closest Cr-O shell and calculations with ab initio computer code FEFF and atomic clusters generated from the chromium-dissolved UO2 structure have been carried out. There is a prominent reduction in the length of the adjacent Cr-O bond of about 0.3 Å in chromia-doped UO2 compared with the ideal U-O bond length in standard UO2 that would be expected because of the change in effective Coulomb interactions resulting from replacing U4+ with Cr3+ and their ionic size differences. The contraction of shortest Cr-U bond is ~0.1 Å relative to the U-U bond length in bulk UO2. The difference in the

  6. Solar hybrid cooling system for high-tech offices in subtropical climate - Radiant cooling by absorption refrigeration and desiccant dehumidification

    International Nuclear Information System (INIS)

    Fong, K.F.; Chow, T.T.; Lee, C.K.; Lin, Z.; Chan, L.S.

    2011-01-01

    Highlights: → A solar hybrid cooling system is proposed for high-tech offices in subtropical climate. → An integration of radiant cooling, absorption refrigeration and desiccant dehumidification. → Year-round cooling and energy performances were evaluated through dynamic simulation. → Its annual primary energy consumption was lower than conventional system up to 36.5%. → The passive chilled beams were more energy-efficient than the active chilled beams. - Abstract: A solar hybrid cooling design is proposed for high cooling load demand in hot and humid climate. For the typical building cooling load, the system can handle the zone cooling load (mainly sensible) by radiant cooling with the chilled water from absorption refrigeration, while the ventilation load (largely latent) by desiccant dehumidification. This hybrid system utilizes solar energy for driving the absorption chiller and regenerating the desiccant wheel. Since a high chilled water temperature generated from the absorption chiller is not effective to handle the required latent load, desiccant dehumidification is therefore involved. It is an integration of radiant cooling, absorption refrigeration and desiccant dehumidification, which are powered up by solar energy. In this study, the application potential of the solar hybrid cooling system was evaluated for the high-tech offices in the subtropical climate through dynamic simulation. The high-tech offices are featured with relatively high internal sensible heat gains due to the intensive office electric equipment. The key performance indicators included the solar fraction and the primary energy consumption. Comparative study was also carried out for the solar hybrid cooling system using two common types of chilled ceilings, the passive chilled beams and active chilled beams. It was found that the solar hybrid cooling system was technically feasible for the applications of relatively higher cooling load demand. The annual primary energy

  7. An efficient method for computing the absorption of solar radiation by water vapor

    Science.gov (United States)

    Chou, M.-D.; Arking, A.

    1981-01-01

    Chou and Arking (1980) have developed a fast but accurate method for computing the IR cooling rate due to water vapor. Using a similar approach, the considered investigation develops a method for computing the heating rates due to the absorption of solar radiation by water vapor in the wavelength range from 4 to 8.3 micrometers. The validity of the method is verified by comparison with line-by-line calculations. An outline is provided of an efficient method for transmittance and flux computations based upon actual line parameters. High speed is achieved by employing a one-parameter scaling approximation to convert an inhomogeneous path into an equivalent homogeneous path at suitably chosen reference conditions.

  8. Ultrabroadband time-resolved THz spectroscopy of polymer-based solar cells

    DEFF Research Database (Denmark)

    Cooke, David G.; Krebs, Frederik C; Jepsen, Peter Uhd

    2011-01-01

    We have developed ultrabroadband THz spectroscopy in reflection mode for characterization of conductivity dynamics in conductive polymer samples used in organic solar cells. The spectrometer is designed to have a time resolution limited only by the duration of the optical pump pulse, thus enabling...... the investigation of charge generation processes on the sub-100-fs time scale....

  9. New insights into the nanostructure of innovative thin film solar cells gained by positron annihilation spectroscopy

    NARCIS (Netherlands)

    Eijt, S.W.H.; Shi, W.; Mannheim, A.; Butterling, M.; Schut, H.; Egger, W; Dickmann, M.; Hugenschmidt, C; Shakeri, B.; Meulenberg, R; Callewaert, V.; Saniz, R; Partoens, B; Barbiellini, B; Bansil, A; Melskens, J.; Zeman, M.; Smets, A.H.M.; Kulbak, M.; Hodes, G.; Cahen, D.; Brück, E.H.

    2017-01-01

    Recent studies showed that positron annihilation methods can provide key insights into the nanostructure and electronic structure of thin film solar cells. In this study, positron annihilation lifetime spectroscopy (PALS) is applied to investigate CdSe quantum dot (QD) light absorbing layers,

  10. Mapping boron in silicon solar cells using electron energy-loss spectroscopy

    DEFF Research Database (Denmark)

    Duchamp, Martial; Boothroyd, Chris; Kovács, András

    2011-01-01

    Electron energy-loss spectroscopy (EELS) is used to study the B distribution in a p-i-n layered solar cell structure. The boron concentration in the p-doped Si layer is expected to be ~1021 cm−3 and should not exceed 1017 cm−3 in the neighbouring intrinsic layer. We show that B concentrations...

  11. Moessbauer spectroscopy of 57Fe and the evolution of the solar system

    International Nuclear Information System (INIS)

    Knudsen, J.M.

    1990-01-01

    The article starts with a brief review of ideas on the origin of the solar system, with emphasis on the cosmic history of the element iron. Some examples of the application of Moessbauer spectroscopy to the study of iron compounds from various types of meteorites, which represent different stages of the evolution of the planetary system, then follow. (orig.)

  12. Some problems connected with boron determination by atomic absorption spectroscopy and the sensitivity improvement

    Directory of Open Access Journals (Sweden)

    JELENA J. SAVOVIC

    2001-08-01

    Full Text Available Two atomizers were compared: an N2O–C2H2 flame and a stabilized U-shaped DC arc with aerosol supply. Both the high plasma temperature and the reducing atmosphere obtained by acetylene addition to the argon stream substantially increase the sensitivity of boron determination by atomic absorption spectroscopy (AAS when the arc atomizer is used. The results were compared with those for silicon as a control element. The experimental characteristic concentrations for both elements were compared with the computed values. The experimentally obtained characteristic concentration for boron when using the arc atomizer was in better agreement with the calculated value. It was estimated that the influence of stable monoxide formation on the sensitivity for both elements was about the same, but reduction of analyte and formation of non-volatile carbide particles was more important for boron, which is the main reason for the low sensitivity of boron determination using a flame atomizer. The use of an arc atomizer suppresses this interference and significantly improves the sensitivity of the determination.

  13. Vibration-rotational overtones absorption of solid hydrogens using optoacoustic spectroscopy technique

    International Nuclear Information System (INIS)

    Vieira, M.M.F.

    1985-01-01

    Vibrational-rotational overtones absorption solid hydrogens (H 2 , D 2 , HD) is studied using pulsed laser piezoeletric transducer (PULPIT) optoacoustic spectroscopy is studied. A general downward shift in energy from isolated molecular energies is observed. Studying normal-hydrogen it was observed that the phonon excitations associated with double-molecular transitions are predominantly transverse-optical phonons, whereas the excitations associated with single-molecular transitions are predominantly longitudinal - optical phonons. Multiplet structures were observed for certain double transitions in parahydrogen and orthodeuterium. The HD spectrum, besides presenting the sharp zero-phonon lines and the associated phonon side bands, like H 2 and D 2 , showed also two different features. This observation was common to all the transitions involving pure rotational excitation in H 2 and D 2 , which showed broad linewidths. This, together with some other facts (fluorescence lifetime *approx*10 5 sec; weak internal vibration and lattice coupling), led to the proposition of a mechanism for the fast nonradiative relaxation in solid hydrogens, implied from some observed experimental evidences. This relaxation, due to strong coupling, would happen in two steps: the internal vibration modes would relax to the rotational modes of the molecules, and then this rotational modes would relax to the lattice vibration modes. (Author) [pt

  14. Phase transitions of amorphous solid acetone in confined geometry investigated by reflection absorption infrared spectroscopy.

    Science.gov (United States)

    Shin, Sunghwan; Kang, Hani; Kim, Jun Soo; Kang, Heon

    2014-11-26

    We investigated the phase transformations of amorphous solid acetone under confined geometry by preparing acetone films trapped in amorphous solid water (ASW) or CCl4. Reflection absorption infrared spectroscopy (RAIRS) and temperature-programmed desorption (TPD) were used to monitor the phase changes of the acetone sample with increasing temperature. An acetone film trapped in ASW shows an abrupt change in the RAIRS features of the acetone vibrational bands during heating from 80 to 100 K, which indicates the transformation of amorphous solid acetone to a molecularly aligned crystalline phase. Further heating of the sample to 140 K produces an isotropic solid phase, and eventually a fluid phase near 157 K, at which the acetone sample is probably trapped in a pressurized, superheated condition inside the ASW matrix. Inside a CCl4 matrix, amorphous solid acetone crystallizes into a different, isotropic structure at ca. 90 K. We propose that the molecularly aligned crystalline phase formed in ASW is created by heterogeneous nucleation at the acetone-water interface, with resultant crystal growth, whereas the isotropic crystalline phase in CCl4 is formed by homogeneous crystal growth starting from the bulk region of the acetone sample.

  15. Total Absorption Spectroscopy of Fission Fragments Relevant for Reactor Antineutrino Spectra and Decay Heat Calculations

    Directory of Open Access Journals (Sweden)

    Porta A.

    2016-01-01

    Full Text Available Beta decay of fission products is at the origin of decay heat and antineutrino emission in nuclear reactors. Decay heat represents about 7% of the reactor power during operation and strongly impacts reactor safety. Reactor antineutrino detection is used in several fundamental neutrino physics experiments and it can also be used for reactor monitoring and non-proliferation purposes. 92,93Rb are two fission products of importance in reactor antineutrino spectra and decay heat, but their β-decay properties are not well known. New measurements of 92,93Rb β-decay properties have been performed at the IGISOL facility (Jyväskylä, Finland using Total Absorption Spectroscopy (TAS. TAS is complementary to techniques based on Germanium detectors. It implies the use of a calorimeter to measure the total gamma intensity de-exciting each level in the daughter nucleus providing a direct measurement of the beta feeding. In these proceedings we present preliminary results for 93Rb, our measured beta feedings for 92Rb and we show the impact of these results on reactor antineutrino spectra and decay heat calculations.

  16. [Detecting Thallium in Water Samples using Dispersive Liquid Phase Microextraction-Graphite Furnace Atomic Absorption Spectroscopy].

    Science.gov (United States)

    Zhu, Jing; Li, Yan; Zheng, Bo; Tang, Wei; Chen, Xiao; Zou, Xiao-li

    2015-11-01

    To develope a method of solvent demulsification dispersive liquid phase microextraction (SD-DLPME) based on ion association reaction coupled with graphite furnace atomic absorption spectroscopy (GFAAS) for detecting thallium in water samples. Methods Thallium ion in water samples was oxidized to Tl(III) with bromine water, which reacted with Cl- to form TlCl4-. The ionic associated compound with trioctylamine was obtained and extracted. DLPME was completed with ethanol as dispersive solvent. The separation of aqueous and organic phase was achieved by injecting into demulsification solvent without centrifugation. The extractant was collected and injected into GFAAS for analysis. With palladium colloid as matrix modifier, a two step drying and ashing temperature programming process was applied for high precision and sensitivity. The linear range was 0.05-2.0 microg/L, with a detection limit of 0.011 microg/L. The relative standard derivation (RSD) for detecting Tl in spiked water sample was 9.9%. The spiked recoveries of water samples ranged from 94.0% to 103.0%. The method is simple, sensitive and suitable for batch analysis of Tl in water samples.

  17. Serial Femtosecond Crystallography and Ultrafast Absorption Spectroscopy of the Photoswitchable Fluorescent Protein IrisFP.

    Science.gov (United States)

    Colletier, Jacques-Philippe; Sliwa, Michel; Gallat, François-Xavier; Sugahara, Michihiro; Guillon, Virginia; Schirò, Giorgio; Coquelle, Nicolas; Woodhouse, Joyce; Roux, Laure; Gotthard, Guillaume; Royant, Antoine; Uriarte, Lucas Martinez; Ruckebusch, Cyril; Joti, Yasumasa; Byrdin, Martin; Mizohata, Eiichi; Nango, Eriko; Tanaka, Tomoyuki; Tono, Kensuke; Yabashi, Makina; Adam, Virgile; Cammarata, Marco; Schlichting, Ilme; Bourgeois, Dominique; Weik, Martin

    2016-03-03

    Reversibly photoswitchable fluorescent proteins find growing applications in cell biology, yet mechanistic details, in particular on the ultrafast photochemical time scale, remain unknown. We employed time-resolved pump-probe absorption spectroscopy on the reversibly photoswitchable fluorescent protein IrisFP in solution to study photoswitching from the nonfluorescent (off) to the fluorescent (on) state. Evidence is provided for the existence of several intermediate states on the pico- and microsecond time scales that are attributed to chromophore isomerization and proton transfer, respectively. Kinetic modeling favors a sequential mechanism with the existence of two excited state intermediates with lifetimes of 2 and 15 ps, the second of which controls the photoswitching quantum yield. In order to support that IrisFP is suited for time-resolved experiments aiming at a structural characterization of these ps intermediates, we used serial femtosecond crystallography at an X-ray free electron laser and solved the structure of IrisFP in its on state. Sample consumption was minimized by embedding crystals in mineral grease, in which they remain photoswitchable. Our spectroscopic and structural results pave the way for time-resolved serial femtosecond crystallography aiming at characterizing the structure of ultrafast intermediates in reversibly photoswitchable fluorescent proteins.

  18. Operando X-ray absorption spectroscopy studies on Pd-SnO2 based sensors.

    Science.gov (United States)

    Koziej, Dorota; Hübner, Michael; Barsan, Nicolae; Weimar, Udo; Sikora, Marcin; Grunwaldt, Jan-Dierk

    2009-10-14

    SnO2 gas sensors with palladium as additive in the range of 0.2 wt% and 3 wt% were studied by in situ X-ray absorption spectroscopy under idealized and real operating conditions. Simultaneously to the structural studies, measurements of the sensing properties were undertaken allowing for the determination of structure-function relationships. For this purpose a new in situ spectroscopic cell was designed which permitted on the one hand sensing on conventional screen printed 50 microm thick sensing layers and on the other hand structural analysis with X-rays provided by an insertion device at a 3rd generation synchrotron facility in fluorescence mode. Pd K-edge XANES and EXAFS results on gas sensors showed that palladium, present in an oxidized state, is finely dispersed if it is added in small quantities (0.2 wt%) while it forms clusters at higher concentrations (3 wt%). This is also reflected by the much easier reduction of palladium in the latter, higher concentrated ones. Under realistic sensing conditions (30-200 ppm H2; 10-50 ppm CO in dry and humid air at 200 and 300 degrees C) for the low additive concentration samples, no change in oxidation state was observed, i.e. palladium remained in its oxidized state. This has important consequences on the understanding and modeling of the gas sensing mechanism.

  19. Ultrafast holography and transient absorption spectroscopy in charge-transfer polymers

    Energy Technology Data Exchange (ETDEWEB)

    McBranch, D.W.; Maniloff, E.S. [Los Alamos National Lab., NM (United States); Vacar, D.; Heeger, A.J. [Univ. of California, Santa Barbara, CA (United States). Institute for Polymers and Organic Solids

    1997-10-01

    Charge-transfer polymers are a new class of nonlinear optical materials which can be used for generating femtosecond holographic gratings. Using semiconducting polymers sensitized with varying concentrations of C{sub 60}, holographic gratings were recorded by individual ultrafast laser pulses; the diffraction efficiency and time decay of the gratings were measured using non-degenerate four-wave mixing. Using a figure of merit for dynamic data processing, the temporal diffraction efficiency, this new class of materials exhibits between two and 12 orders of magnitude higher response than previous reports. The charge transfer range at polymer/C{sub 60} interfaces was further studied using transient absorption spectroscopy. The fact that charge-transfer occurs in the picosecond-time scale in bilayer structures (thickness 200 {angstrom}) implies that diffusion of localized excitations to the interface is not the dominant mechanism; the charge transfer range is a significant fraction of the film thickness. From analysis of the excited state decay curves, we estimate the charge transfer range to be 80 {angstrom} and interpret that range as resulting from quantum delocalization of the photoexcitations.

  20. Development of a portable heavy-water leak sensor based on laser absorption spectroscopy

    International Nuclear Information System (INIS)

    Lee, Lim; Park, Hyunmin; Kim, Taek-Soo; Kim, Minho; Jeong, Do-Young

    2016-01-01

    Highlights: • We developed a compact and portable laser sensor for a detection of heavy water leakage. • The sensor is wearable and also easy to use to search for the leak point. • It is sensitive enough to find invisible very tiny leaks. - Abstract: A compact and portable leak sensor based on cavity enhanced absorption spectroscopy has been newly developed for a detection of heavy water leakage which may happen in the facilities using heavy water such as pressurized heavy water reactor (PHWR). The developed portable sensor is suitable as an individual instrument for the measuring leak rate and finding the leak location because it is sufficiently compact in size and weight and operated by using an internal battery. In the performance test, the minimum detectable leak rate was estimated as 0.05 g/day from the calibration curve. This new sensor is expected to be a reliable and promising device for the detection of heavy water leakage since it has advantages on real-time monitoring and early detection for nuclear safety.

  1. Environmental samples analysis by Atomic Absorption Spectrophotometry and Inductively Coupled Plasma-Optical Emission Spectroscopy

    International Nuclear Information System (INIS)

    Popescu, I.V.; Iordan, M.; Stihi, C.; Bancuta, A.; Busuioc, G.; Dima, G.; Ciupina, V.; Belc, M.; Vlaicu, Gh.; Marian, R.

    2002-01-01

    Biological samples are interesting from many aspects of environmental monitoring. By analyzing tree leaves conclusions can be drown regarding the metal loading in the growth medium. So that, starting from assumption that the pollution factors from environmental medium can modify the normal concentration of elements, we decided to control the presence of toxic elements and the deviation from normal state of elements in leaves of different trees from areas situated at different distances of pollution source. The aim of this work is to determine the elemental composition of tree leaves using Atomic Absorption Spectrophotometry (AAS) method and Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) method. Using AAS spectrophotometer SHIMADZU we identified and determined the concentration of: Cd, Co, Cu, Zn, Mn, Cr, Fe, Se, Pb with an instrumental error less than 1% for most of the elements analyzed. The same samples were analyzed by ICP-OES spectrometer, BAIRD ICP2070-Sequential Plasma spectrometer. We identified and determined in leaves of different trees the concentration of Mg, Ca, and Sr with a precision less than 6%. (authors)

  2. SUT-NANOTEC-SLRI beamline for X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Klysubun, Wantana; Kidkhunthod, Pinit; Tarawarakarn, Pongjakr; Sombunchoo, Panidtha; Kongmark, Chanapa; Limpijumnong, Sukit; Rujirawat, Saroj; Yimnirun, Rattikorn; Tumcharern, Gamolwan; Faungnawakij, Kajornsak

    2017-04-04

    The SUT-NANOTEC-SLRI beamline was constructed in 2012 as the flagship of the SUT-NANOTEC-SLRI Joint Research Facility for Synchrotron Utilization, co-established by Suranaree University of Technology (SUT), National Nanotechnology Center (NANOTEC) and Synchrotron Light Research Institute (SLRI). It is an intermediate-energy X-ray absorption spectroscopy (XAS) beamline at SLRI. The beamline delivers an unfocused monochromatic X-ray beam of tunable photon energy (1.25–10 keV). The maximum normal incident beam size is 13 mm (width) × 1 mm (height) with a photon flux of 3 × 108to 2 × 1010 photons s-1(100 mA)-1varying across photon energies. Details of the beamline and XAS instrumentation are described. To demonstrate the beamline performance,K-edge XANES spectra of MgO, Al2O3, S8, FeS, FeSO4, Cu, Cu2O and CuO, and EXAFS spectra of Cu and CuO are presented.

  3. Depth-selective X-ray absorption spectroscopy by detection of energy-loss Auger electrons

    International Nuclear Information System (INIS)

    Isomura, Noritake; Soejima, Narumasa; Iwasaki, Shiro; Nomoto, Toyokazu; Murai, Takaaki; Kimoto, Yasuji

    2015-01-01

    Graphical abstract: - Highlights: • A unique XAS method is proposed for depth profiling of chemical states. • PEY mode detecting energy-loss electrons enables a variation in the probe depth. • Si K-edge XAS spectra of the Si 3 N 4 /SiO 2 /Si multilayer films have been investigated. • Deeper information was obtained in the spectra measured at larger energy loss. • Probe depth could be changed by the selection of the energy of detected electrons. - Abstract: A unique X-ray absorption spectroscopy (XAS) method is proposed for depth profiling of chemical states in material surfaces. Partial electron yield mode detecting energy-loss Auger electrons, called the inelastic electron yield (IEY) mode, enables a variation in the probe depth. As an example, Si K-edge XAS spectra for a well-defined multilayer sample (Si 3 N 4 /SiO 2 /Si) have been investigated using this method at various kinetic energies. We found that the peaks assigned to the layers from the top layer to the substrate appeared in the spectra in the order of increasing energy loss relative to the Auger electrons. Thus, the probe depth can be changed by the selection of the kinetic energy of the energy loss electrons in IEY-XAS.

  4. Design of differential optical absorption spectroscopy long-path telescopes based on fiber optics.

    Science.gov (United States)

    Merten, André; Tschritter, Jens; Platt, Ulrich

    2011-02-10

    We present a new design principle of telescopes for use in the spectral investigation of the atmosphere and the detection of atmospheric trace gases with the long-path differential optical absorption spectroscopy (DOAS) technique. A combination of emitting and receiving fibers in a single bundle replaces the commonly used coaxial-Newton-type combination of receiving and transmitting telescope. This very simplified setup offers a higher light throughput and simpler adjustment and allows smaller instruments, which are easier to handle and more portable. The higher transmittance was verified by ray-tracing calculations, which result in a theoretical factor threefold improvement in signal intensity compared with the old setup. In practice, due to the easier alignment and higher stability, up to factor of 10 higher signal intensities were found. In addition, the use of a fiber optic light source provides a better spectral characterization of the light source, which results in a lower detection limit for trace gases studied with this instrument. This new design will greatly enhance the usability and the range of applications of active DOAS instruments.

  5. Evaluation on corrosively dissolved gold induced by alkanethiol monolayer with atomic absorption spectroscopy

    International Nuclear Information System (INIS)

    Cao Zhong; Zhang Ling; Guo Chaoyan; Gong Fuchun; Long Shu; Tan Shuzhen; Xia Changbin; Xu Fen; Sun Lixian

    2009-01-01

    We have monitored a gold corrosive dissolution behavior accompanied in n-alkanethiol like n-dodecanethiol assembled process with in situ quartz crystal microbalance (QCM), and then observed it with atomic force microscopy (AFM) which showed an evident image of corrosive defects or holes produced on gold substrate, corresponding to gold dissolution induced by the alkanethiol molecules in the presence of oxygen. For detection of the dissolved gold defects during alkanethiol assembled process, an atomic absorption spectroscopy (AAS) has been carried out in this paper, and the detection limit for the dissolved gold could be evaluated to be 15.4 ng/mL. The amount of dissolved gold from the substrates of gold plates as functions of immersion time, acid media, solvents and thiol concentration has been examined in the oxygen saturated solutions. In comparison with in situ QCM method, the kinetics behavior of the long-term gold corrosion on the gold plates in 1.0 mmol/L of n-dodecanethiol solution determined with AAS method was a slow process, and its corrosion rate on gold dissolution could be evaluated to be about 4.4 x 10 -5 ng.cm -2 .s -1 , corresponding to 1.3 x 10 8 Au atoms.cm -2 .s -1 , that was much smaller than that of initial rate monitored with in situ QCM. Both kinetics equations obtained with QCM and AAS showed a consistent corrosion behavior on gold surfaces.

  6. Ozone monitoring using differential optical absorption spectroscopy (DOAS) and UV photometry instruments in Sohar, Oman.

    Science.gov (United States)

    Nawahda, Amin

    2015-08-01

    Ground level ozone (O3) concentrations were measured across Sohar highway in Oman during a four-month period from September to December 2014 by using an open-path deferential optical absorption spectroscopy (DOAS) instrument. The monthly average concentrations of O3 varied from 19.6 to 29.4 ppb. The measurements of O3 are compared with the measurements of a non-open-path UV photometry analyzer (UVP). The percent difference (PD) concept and linear regression methods were used to compare the readings of the two instruments. The findings show high correlation coefficients between the measurements of the DOAS and UVP instruments. The DOAS measurements of O3 are found to be less than those measured by the UVP instrument; the correlation coefficients between absolute PD values and meteorological parameters and PM2.5 were very low indicating a minor effect; therefore, titrations of O3 by traffic emissions and difference in elevation could be the reason for the difference in the measurements of the two instruments.

  7. Non-invasive gas monitoring in newborn infants using diode laser absorption spectroscopy: a case study

    Science.gov (United States)

    Lundin, Patrik; Svanberg, Emilie K.; Cocola, Lorenzo; Lewander, Märta; Andersson-Engels, Stefan; Jahr, John; Fellman, Vineta; Svanberg, Katarina; Svanberg, Sune

    2012-03-01

    Non-invasive diode laser spectroscopy was, for the first time, used to assess gas content in the intestines and the lungs of a new-born, 4 kg, baby. Two gases, water vapor and oxygen, were studied with two low-power tunable diode lasers, illuminating the surface skin tissue and detecting the diffusely emerging light a few centimeters away. The light, having penetrated into the tissue, had experienced absorption by gas located in the lungs and in the intestines. Very distinct water vapor signals were obtained from the intestines while imprint from oxygen was lacking, as expected. Detectable, but minor, signals of water vapor were also obtained from the lungs, illuminating the armpit area and detecting below the collar bone. Water vapor signals were seen but again oxygen signals were lacking, now due to the difficulties of penetration of the oxygen probing light into the lungs of this full-term baby. Ultra-sound images were obtained both from the lungs and from the stomach of the baby. Based on dimensions and our experimental findings, we conclude, that for early pre-term babies, also oxygen should be detectable in the lungs, in addition to intestine and lung detection of water vapor. The present paper focuses on the studies of the intestines while the lung studies will be covered in a forthcoming paper.

  8. X-ray absorption spectroscopy investigations on radioactive matter using MARS beamline at SOLEIL synchrotron

    Energy Technology Data Exchange (ETDEWEB)

    Llorens, Isabelle; Solari, Pier Lorenzo; Sitaud, Bruno [Synchrotron SOLEIL - l' Orme des Merisiers Saint Aubin, Gif-sur-Yvette (France); and others

    2014-07-01

    The MARS beamline at the SOLEIL synchrotron is dedicated to the characterization of radioactive material samples. One great advantage of the beamline is the possibility to characterize about 380 radionuclides by different X-ray techniques in the same place. This facility is unique in Europe. A wide energy range from around 3.5 keV to 36 keV K-edges from K to Cs, and L3 edges from Cd to Am and beyond can be used. The MARS beamline is optimized for X-ray absorption spectroscopy techniques (XANES/EXAFS), powder diffraction (XRD) but X-ray fluorescence (XRF) analysis, High Energy Resolution Fluorescence Detected-XAS (HERFD-XAS), X-ray Emission (XES) and μ-XAS/XRD are also possible. A description of the beamline as well as its performances are given in a first part. Then some scientific examples of XAS studies from users are presented which cover a wide variety of topics in radiochemistry and nuclear materials.

  9. Cadmium accumulation in the crayfish, Procambarus clarkii, using graphite furnace atomic absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Diaz-Mayans, J.; Hernandez, F.; Medina, J.; Del Ramo, J.; Torreblanca, A.

    1986-11-01

    Lake Albufera and the surrounding rice-field waters are being subject to very heavy loads of sewage and toxic industrial residues (including heavy metals and pesticides) from the many urban and wastewaters in this area. The American red crayfish Procambarus clarkii is native to the Louisiana marshes (USA). In 1978, the crayfish appeared in Lake Albufera near Valencia (Spain), and presently, without adequate sanitary controls, the crayfish is being fished commercially for human consumption. In view of this interest, it is important to have accurate information on concentrations of cadmium in natural waters and cadmium levels of tissues of freshwaters animals used as human food, as well as the accumulation rates of this metal in this animal. In the present study, the authors investigated the accumulation of cadmium in several tissues of the red crayfish, P clarkii (Girard) from Lake Albufera following cadmium exposure. Determinations of cadmium were made by flameless atomic absorption spectroscopy and the standard additions method. Digestion of samples was made by wet ashing in open flasks with concentrated HNO/sub 3/ at 80-90/sup 0/C.

  10. Combined tunable diode laser absorption spectroscopy and monochromatic radiation thermometry in ammonium dinitramide-based thruster

    Science.gov (United States)

    Zeng, Hui; Ou, Dongbin; Chen, Lianzhong; Li, Fei; Yu, Xilong

    2018-02-01

    Nonintrusive temperature measurements for a real ammonium dinitramide (ADN)-based thruster by using tunable diode laser absorption spectroscopy and monochromatic radiation thermometry are proposed. The ADN-based thruster represents a promising future space propulsion employing green, nontoxic propellant. Temperature measurements in the chamber enable quantitative thermal analysis for the thruster, providing access to evaluate thermal properties of the thruster and optimize thruster design. A laser-based sensor measures temperature of combustion gas in the chamber, while a monochromatic thermometry system based on thermal radiation is utilized to monitor inner wall temperature in the chamber. Additional temperature measurements of the outer wall temperature are conducted on the injector, catalyst bed, and combustion chamber of the thruster by using thermocouple, respectively. An experimental ADN thruster is redesigned with optimizing catalyst bed length of 14 mm and steady-state firing tests are conducted under various feed pressures over the range from 5 to 12 bar at a typical ignition temperature of 200°C. A threshold of feed pressure higher than 8 bar is required for the thruster's normal operation and upstream movement of the heat release zone is revealed in the combustion chamber out of temperature evolution in the chamber.

  11. Oxygen diluted hexamethyldisiloxane plasmas investigated by means of in situ infrared absorption spectroscopy and mass spectrometry

    Science.gov (United States)

    Magni, D.; Deschenaux, Ch; Hollenstein, Ch; Creatore, A.; Fayet, P.

    2001-01-01

    The gas phase species produced in rf plasmas of hexamethyldisiloxane (HMDSO), Si2O(CH3)6, diluted with oxygen, have been investigated. The complementarity of Fourier transform infrared absorption spectroscopy and mass spectrometry allows the determination of the most abundant neutral components present in the discharge. The measurements reveal that methyl groups (CH3), abundantly formed by the dissociation of the HMDSO molecule, are the precursor for the most abundant species which stem from two kinds of reaction. The first kind of reaction is combustion of CH3 by oxygen-producing formaldehyde (COH2), formic acid (CO2H2), carbon monoxide (CO), carbon dioxide (CO2) and water. It is shown that high mass carbonated radicals, such as SixOyCzHt, first diffuse to the surface and then the carbon is removed by oxygen etching to form CO2. The second is hydrocarbon chemistry promoted by CH3, producing mainly hydrogen (H2), methane (CH4) and acetylene (C2H2).

  12. Determination of lithium in sodium by vacuum distillation-graphite furnace atomic absorption spectroscopy

    International Nuclear Information System (INIS)

    Xie Chun; Sun Shiping; Jia Yunteng; Wen Ximeng

    1996-12-01

    When sodium is used as a coolant in China Experimental Fast Reactor, the lithium content in sodium has an effect on the nuclear property of reactor. A method has been developed to determine the trace lithium in sodium metal at the level of less than ten parts per million. About 0.4 g sodium is placed into a high-purity tantalum crucible, then it is placed in a stainless-steel still to distill at 360 degree C under vacuum (0.01 Pa). After the sodium has been removed, the residue is dissolved by nitric acid (1:2) and analyzed with Graphite Furnace Atomic Absorption Spectroscopy at 671.0 nm wavelength. The distillation conditions, working conditions of the instrument and interferences from matrix sodium, acid and concomitant elements have been studied. Standard addition experiments are carried out with lithium chloride and lithium nitrate. The percentage recoveries are 96.8% and 97.4% respectively. The relative standard deviation is less than +- 5%. The method has been used to determine lithium content in high pure sodium and industrial grade sodium. (11 refs., 5 figs., 5 tabs.)

  13. Flame monitoring of a model swirl injector using 1D tunable diode laser absorption spectroscopy tomography

    Science.gov (United States)

    Liu, Chang; Cao, Zhang; Li, Fangyan; Lin, Yuzhen; Xu, Lijun

    2017-05-01

    Distributions of temperature and H2O concentration in a swirling flame are critical to evaluate the performance of a gas turbine combustor. In this paper, 1D tunable diode laser absorption spectroscopy tomography (1D-TDLAST) was introduced to monitor swirling flames generated from a model swirl injector by simultaneously reconstructing the rotationally symmetric distributions of temperature and H2O concentration. The optical system was sufficiently simplified by introducing only one fan-beam illumination and a linear detector array of 12 equally-spaced photodetectors. The fan-beam illumination penetrated a cross section of interest in the swirling flame and the transmitted intensities were detected by the detector array. With the transmitted intensities in hand, projections were extracted and employed by a 1D tomographic algorithm to reconstruct the distributions of temperature and H2O concentration. The route of the precessing vortex core generated in the swirling flame can be easily inferred from the reconstructed profiles of temperature and H2O concentration at different heights above the nozzle of the swirl injector.

  14. The impacts of different expansion modes on performance of small solar energy firms: perspectives of absorptive capacity.

    Science.gov (United States)

    Chen, Hsing Hung; Shen, Tao; Xu, Xin-Long; Ma, Chao

    2013-01-01

    The characteristics of firm's expansion by differentiated products and diversified products are quite different. However, the study employing absorptive capacity to examine the impacts of different modes of expansion on performance of small solar energy firms has never been discussed before. Then, a conceptual model to analyze the tension between strategies and corporate performance is proposed to filling the vacancy. After practical investigation, the results show that stronger organizational institutions help small solar energy firms expanded by differentiated products increase consistency between strategies and corporate performance; oppositely, stronger working attitudes with weak management controls help small solar energy firms expanded by diversified products reduce variance between strategies and corporate performance.

  15. Detector LENS as a new tool for solar neutrino spectroscopy

    International Nuclear Information System (INIS)

    Kornoukhov, V.N.

    2001-01-01

    LENS detector is a low-threshold, electron-flavor specific detector for real time measurement of the solar neutrino spectrum at low energies. It is expected that 20 tons of Yb used as a neutrino target should give several hundred events per year. The basic method for implementation of the LENS detector is scintillator technique, namely a liquid scintillator doped (up to 10% in mass) with natural Yb

  16. Fullerene-Based Photoactive Layers for Heterojunction Solar Cells: Structure, Absorption Spectra and Charge Transfer Process

    Directory of Open Access Journals (Sweden)

    Yuanzuo Li

    2014-12-01

    Full Text Available The electronic structure and optical absorption spectra of polymer APFO3, [70]PCBM/APFO3 and [60]PCBM/APFO3, were studied with density functional theory (DFT, and the vertical excitation energies were calculated within the framework of the time-dependent DFT (TD-DFT. Visualized charge difference density analysis can be used to label the charge density redistribution for individual fullerene and fullerene/polymer complexes. The results of current work indicate that there is a difference between [60]PCBM and [70]PCBM, and a new charge transfer process is observed. Meanwhile, for the fullerene/polymer complex, all calculations of the twenty excited states were analyzed to reveal all possible charge transfer processes in depth. We also estimated the electronic coupling matrix, reorganization and Gibbs free energy to further calculate the rates of the charge transfer and the recombination. Our results give a clear picture of the structure, absorption spectra, charge transfer (CT process and its influencing factors, and provide a theoretical guideline for designing further photoactive layers of solar cells.

  17. Model of yield response of corn to plant population and absorption of solar energy.

    Science.gov (United States)

    Overman, Allen R; Scholtz, Richard V

    2011-01-31

    Biomass yield of agronomic crops is influenced by a number of factors, including crop species, soil type, applied nutrients, water availability, and plant population. This article is focused on dependence of biomass yield (Mg ha(-1) and g plant(-1)) on plant population (plants m(-2)). Analysis includes data from the literature for three independent studies with the warm-season annual corn (Zea mays L.) grown in the United States. Data are analyzed with a simple exponential mathematical model which contains two parameters, viz. Y(m) (Mg ha(-1)) for maximum yield at high plant population and c (m(2) plant(-1)) for the population response coefficient. This analysis leads to a new parameter called characteristic plant population, x(c) = 1/c (plants m(-2)). The model is shown to describe the data rather well for the three field studies. In one study measurements were made of solar radiation at different positions in the plant canopy. The coefficient of absorption of solar energy was assumed to be the same as c and provided a physical basis for the exponential model. The three studies showed no definitive peak in yield with plant population, but generally exhibited asymptotic approach to maximum yield with increased plant population. Values of x(c) were very similar for the three field studies with the same crop species.

  18. Model of yield response of corn to plant population and absorption of solar energy.

    Directory of Open Access Journals (Sweden)

    Allen R Overman

    Full Text Available Biomass yield of agronomic crops is influenced by a number of factors, including crop species, soil type, applied nutrients, water availability, and plant population. This article is focused on dependence of biomass yield (Mg ha(-1 and g plant(-1 on plant population (plants m(-2. Analysis includes data from the literature for three independent studies with the warm-season annual corn (Zea mays L. grown in the United States. Data are analyzed with a simple exponential mathematical model which contains two parameters, viz. Y(m (Mg ha(-1 for maximum yield at high plant population and c (m(2 plant(-1 for the population response coefficient. This analysis leads to a new parameter called characteristic plant population, x(c = 1/c (plants m(-2. The model is shown to describe the data rather well for the three field studies. In one study measurements were made of solar radiation at different positions in the plant canopy. The coefficient of absorption of solar energy was assumed to be the same as c and provided a physical basis for the exponential model. The three studies showed no definitive peak in yield with plant population, but generally exhibited asymptotic approach to maximum yield with increased plant population. Values of x(c were very similar for the three field studies with the same crop species.

  19. A review on the recent development of solar absorption and vapour compression based hybrid air conditioning with low temperature storage

    Directory of Open Access Journals (Sweden)

    Noor D. N.

    2016-01-01

    Full Text Available Conventional air conditioners or vapour compression systems are main contributors to energy consumption in modern buildings. There are common environmental issues emanating from vapour compression system such as greenhouse gas emission and heat wastage. These problems can be reduced by adaptation of solar energy components to vapour compression system. However, intermittence input of daily solar radiation was the main issue of solar energy system. This paper presents the recent studies on hybrid air conditioning system. In addition, the basic vapour compression system and components involved in the solar air conditioning system are discussed. Introduction of low temperature storage can be an interactive solution and improved economically which portray different modes of operating strategies. Yet, very few studies have examined on optimal operating strategies of the hybrid system. Finally, the findings of this review will help suggest optimization of solar absorption and vapour compression based hybrid air conditioning system for future work while considering both economic and environmental factors.

  20. Thermodynamic optimization of a solar system for cogeneration of water heating/purification and absorption cooling

    Science.gov (United States)

    Hovsapian, Zohrob O.

    This dissertation presents a contribution to understanding the behavior of solar powered air conditioning and refrigeration systems with a view to determining the manner in which refrigeration rate; mass flows, heat transfer areas, and internal architecture are related. A cogeneration system consisting of a solar concentrator, a cavity-type receiver, a gas burner, and a thermal storage reservoir is devised to simultaneously produce water heating/purification and cooling (absorption refrigerator system). A simplified mathematical model, which combines fundamental and empirical correlations, and principles of classical thermodynamics, mass and heat transfer, is developed. An experimental setup was built to adjust and validate the numerical results obtained with the mathematical model. The proposed model is then utilized to simulate numerically the system transient and steady state response under different operating and design conditions. A system global optimization for maximum performance (or minimum exergy destruction) in the search for minimum pull-down and pull-up times, and maximum system second law efficiency is performed with low computational time. Appropriate dimensionless groups are identified and the results presented in normalized charts for general application. The numerical results show that the three way maximized system second law efficiency, etaII,max,max,max, occurs when three system characteristic mass flow rates are optimally selected in general terms as dimensionless heat capacity rates, i.e., (Psisps , Psiwxwx, PsiHs)opt ≅ (1.43, 0.17, 0.19). The minimum pull-down and pull-up times, and maximum second law efficiencies found with respect to the optimized operating parameters are sharp and, therefore important to be considered in actual design. As a result, the model is expected to be a useful tool for simulation, design, and optimization of solar energy systems in the context of distributed power generation.

  1. Solar-absorption measurements of ozone from two ground based FTIR sites

    Science.gov (United States)

    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

  2. [Ru(bpy)(3)](2+) as a reference in transient absorption spectroscopy: differential absorption coefficients for formation of the long-lived (3)MLCT excited state.

    Science.gov (United States)

    Müller, Pavel; Brettel, Klaus

    2012-04-01

    Transient absorption spectroscopy and other time-resolved methods are commonly used to study chemical reactions and biological processes induced by absorption of light. In order to scale the signal amplitude or to compare results obtained under different conditions, it is advisable to use a reference system, a standard of convenient and well-defined properties. Finding Tris(bipyridine)ruthenium(ii), [Ru(bpy)(3)](2+), a suitable candidate for a transient-absorption spectroscopy reference due to its favourable photochemical properties, we have determined accurate relative values of differential molar absorption coefficients (Δε) for light-induced formation of the metal-to-ligand charge transfer (MLCT) excited triplet state at several relevant wavelengths (wavelengths of commercially available lasers) in the UV and visible regions. We have also attempted to determine the absolute value of Δε close to the wavelength of maximum bleaching (∼450 nm) and we propose to narrow down the interval of conceivable values for Δε(450) from the broad range of published values (-0.88 × 10(4) M(-1)cm(-1) to -1.36 × 10(4) M(-1)cm(-1)) to -1.1 × 10(4) M(-1)cm(-1)± 15%. Having ourselves successfully applied [Ru(bpy)(3)](2+) as a standard in a recent time-resolved study of enzymatic DNA repair, we would like to encourage other scientists to use this convenient tool as a reference in their future spectroscopic studies on time scales from picoseconds to hundreds of nanoseconds.

  3. Infrared Spectroscopy of CO Ro-vibrational Absorption Lines toward the Obscured AGN IRAS 08572+3915

    OpenAIRE

    Shirahata, Mai; Nakagawa, Takao; Usuda, Tomonori; Goto, Miwa; Suto, Hiroshi; Geballe, T. R.

    2012-01-01

    We present high-resolution spectroscopy of gaseous CO absorption in the fundamental ro-vibrational band toward the heavily obscured active galactic nucleus (AGN) IRAS 08572+3915. We have detected absorption lines up to highly excited rotational levels (J 200 km s-1) of which is due to blueshifted (-160 km s-1) gas at a temperature of ~ 270 K absorbing at velocities as high as -400 km s-1. A much weaker but even warmer (~ 700 K) component, which is highly redshifted (+100 km s-1), is also dete...

  4. On-chip cavity-enhanced absorption spectroscopy using a white light-emitting diode and polymer mirrors.

    Science.gov (United States)

    Rushworth, Cathy M; Jones, Gareth; Fischlechner, Martin; Walton, Emma; Morgan, Hywel

    2015-02-07

    We have developed a disposable microfluidic chip with integrated cavity mirrors comprised of two pieces of 3M Vikuiti™ enhanced specular reflector II (ESRII) film, for performing cavity-enhanced absorption spectroscopy with a white light-emitting diode (LED). Compared to measurements made with a chip without cavity mirrors, the absorption path length is enhanced by a maximum factor of 28 at 544 nm, and the sensitivity is enhanced by approximately 5 times, enabling micromolar range detection limits to be achieved in an optical path length of only 50 μm.

  5. Ultrafast dynamics of two copper bis-phenanthroline complexes measured by x-ray transient absorption spectroscopy

    DEFF Research Database (Denmark)

    Kelley, Matthew S.; Shelby, Megan L.; Mara, Michael W.

    2017-01-01

    Ultrafast structural dynamics of the metal to ligand charge transfer (MLCT) states of two copper bis-phenanthroline complexes were captured by using x-ray transient absorption (XTA) spectroscopy at the Linac Coherent Light Source and further described by theoretical calculations. These complexes......(I)(dpps)2]+ possesses two bulky phenyl-sulfonate groups attached to each phen ligand that force the molecule to adopt a flattened tetrahedral geometry in the ground state. Previously, optical transient absorption (OTA) and synchrotron based XTA experiments with 100 ps time resolution have been employed...

  6. Nonuniform Effect of Carrier Separation Efficiency and Light Absorption in Type-II Perovskite Nanowire Solar Cells.

    Science.gov (United States)

    Wang, Weiping; He, Jialun; Cao, Yiyan; Kong, Lijing; Zheng, Xuanli; Wu, Yaping; Chen, Xiaohong; Li, Shuping; Wu, Zhiming; Kang, Junyong

    2017-12-01

    Coaxial structures exhibit great potential for the application of high-efficiency solar cells due to the novel mechanism of radial charge separation. Here, we intensively investigate the nonuniform effect of carrier separation efficiency (CSE) and light absorption in perovskite-based type-II coaxial nanowire solar cells (ZnO/CH 3 NH 3 PbI 3 ). Results show that the CSE rapidly decreases along the radial direction in the shell, and the value at the outer side becomes extremely low for the thick shell. Besides, the position of the main light absorption gradually moves to the outer side with the increase of the shell thickness. As a result, the external quantum efficiency shows a positional dependence with a maximal value close to the border of the nanowire. Eventually, in our case, it is found that the maximal power conversion efficiency of the solar cells reduces from 19.5 to 17.9% under the effect of the nonuniformity of CSE and light absorption. This work provides a basis for the design of high-efficiency solar cells, especially type-II nanowire solar cells.

  7. Nonuniform Effect of Carrier Separation Efficiency and Light Absorption in Type-II Perovskite Nanowire Solar Cells

    Science.gov (United States)

    Wang, Weiping; He, Jialun; Cao, Yiyan; Kong, Lijing; Zheng, Xuanli; Wu, Yaping; Chen, Xiaohong; Li, Shuping; Wu, Zhiming; Kang, Junyong

    2017-03-01

    Coaxial structures exhibit great potential for the application of high-efficiency solar cells due to the novel mechanism of radial charge separation. Here, we intensively investigate the nonuniform effect of carrier separation efficiency (CSE) and light absorption in perovskite-based type-II coaxial nanowire solar cells (ZnO/CH3NH3PbI3). Results show that the CSE rapidly decreases along the radial direction in the shell, and the value at the outer side becomes extremely low for the thick shell. Besides, the position of the main light absorption gradually moves to the outer side with the increase of the shell thickness. As a result, the external quantum efficiency shows a positional dependence with a maximal value close to the border of the nanowire. Eventually, in our case, it is found that the maximal power conversion efficiency of the solar cells reduces from 19.5 to 17.9% under the effect of the nonuniformity of CSE and light absorption. This work provides a basis for the design of high-efficiency solar cells, especially type-II nanowire solar cells.

  8. Using resonance light scattering and UV/vis absorption spectroscopy to study the interaction between gliclazide and bovine serum albumin.

    Science.gov (United States)

    Zhang, Qiu-Ju; Liu, Bao-Sheng; Li, Gai-Xia; Han, Rong

    2016-08-01

    At different temperatures (298, 310 and 318 K), the interaction between gliclazide and bovine serum albumin (BSA) was investigated using fluorescence quenching spectroscopy, resonance light scattering spectroscopy and UV/vis absorption spectroscopy. The first method studied changes in the fluorescence of BSA on addition of gliclazide, and the latter two methods studied the spectral change in gliclazide while BSA was being added. The results indicated that the quenching mechanism between BSA and gliclazide was static. The binding constant (Ka ), number of binding sites (n), thermodynamic parameters, binding forces and Hill's coefficient were calculated at three temperatures. Values for the binding constant obtained using resonance light scattering and UV/vis absorption spectroscopy were much greater than those obtained from fluorescence quenching spectroscopy, indicating that methods monitoring gliclazide were more accurate and reasonable. In addition, the results suggest that other residues are involved in the reaction and the mode 'point to surface' existed in the interaction between BSA and gliclazide. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  9. X-ray absorption spectroscopy of PbMoO4 single crystals

    Indian Academy of Sciences (India)

    Administrator

    of 2000 eV at 20,000 eV and the channels of the CCD detector were calibrated by recording the absorption edges of standard Mo and Nb foils in the same setting. The absorption spectra ... self-supporting pellets were prepared using a hydraulic press. 2.1 Computation of sample concentration for absorption measurements.

  10. In situ X-ray absorption spectroscopy of transition metal based water oxidation catalysts

    NARCIS (Netherlands)

    van Oversteeg, Christina H M|info:eu-repo/dai/nl/413490483; Doan, Hoang Q; de Groot, Frank M F|info:eu-repo/dai/nl/08747610X; Cuk, Tanja

    2016-01-01

    X-ray absorption studies of the geometric and electronic structure of primarily heterogeneous Co, Ni, and Mn based water oxidation catalysts are reviewed. The X-ray absorption near edge and extended X-ray absorption fine structure studies of the metal K-edge, characterize the metal oxidation state,

  11. Absorption spectroscopy of complex rare earth ion doped hybrid materials over a broad wavelength range

    NARCIS (Netherlands)

    Dekker, R.; Worhoff, Kerstin; Stouwdam, J.W.; van Veggel, F.C.J.M.; Driessen, A.

    2005-01-01

    In the present work we applied a measurement setup to determine several relevant properties of rare-earth doped nanoparticles dispersed in polymer slab waveguides in a single absorption measurement: background absorption of the polymer host material, water absorption, polymer composition

  12. Absorption spectroscopy of complex rare earth ion doped hybrid materials over a broad wavelength range

    NARCIS (Netherlands)

    Dekker, R.; Worhoff, Kerstin; Stouwdam, J.W.; van Veggel, F.C.J.M.; Driessen, A.

    In the present work we applied a measurement setup to determine several relevant properties of rare-earth doped nanoparticles dispersed in polymer slab waveguides in a single absorption measurement: background absorption of the polymer host material, water absorption, polymer composition

  13. Correlated single-crystal electronic absorption spectroscopy and X-ray crystallography at NSLS beamline X26-C

    International Nuclear Information System (INIS)

    Orville, A.M.; Buono, R.; Cowan, M.; Heroux, A.; Shea-McCarthy, G.; Schneider, D.K.; Skinner, J.M.; Skinner, M.J.; Stoner-Ma, D.; Sweet, R.M.

    2011-01-01

    The research philosophy and new capabilities installed at NSLS beamline X26-C to support electronic absorption and Raman spectroscopies coupled with X-ray diffraction are reviewed. This beamline is dedicated full time to multidisciplinary studies with goals that include revealing the relationship between the electronic and atomic structures in macromolecules. The beamline instrumentation has been fully integrated such that optical absorption spectra and X-ray diffraction images are interlaced. Therefore, optical changes induced by X-ray exposure can be correlated with X-ray diffraction data collection. The installation of Raman spectroscopy into the beamline is also briefly reviewed. Data are now routinely generated almost simultaneously from three complementary types of experiments from the same sample. The beamline is available now to the NSLS general user population.

  14. Local structure near actinides and nucleating elements in borosilicate glass for nuclear industry: Results of X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Petit-Maire, D.

    1988-01-01

    Possibilities and limits of X-ray absorption spectroscopy for cation site description in silicate glasses and possible applications for complex glasses, like glass for fission product containment, are examined. In borosilicate glasses two types of sites are evidenced for actinides at the valence 4: Coordinance 6 sites with a narrow radial distribution for the distance An-0; higher coordination (7, 8 or more) with a wider and asymmetrical radial distribution. Proportion of low coordinance sites increases when cation size decreases (Th > Np). U and Np VI and V are characterized as actinyles with a chain 0-An-0 practically linear, coordinance in a plane perpendicular to this complex is probably 5. X-ray absorption spectroscopy allows an accurate description of actinide sites in fission product glasses [fr

  15. Biomimetic spiral grating for stable and highly efficient absorption in crystalline silicon thin-film solar cells

    KAUST Repository

    Hou, Jin

    2017-09-12

    By emulating the phyllotaxis structure of natural plants, which has an efficient and stable light capture capability, a two-dimensional spiral grating is introduced on the surface of crystalline silicon solar cells to obtain both efficient and stable light absorption. Using the rigorous coupled wave analysis method, the absorption performance on structural parameter variations of spiral gratings is investigated firstly. Owing to diffraction resonance and excellent superficies antireflection, the integrated absorption of the optimal spiral grating cell is raised by about 77 percent compared with the conventional slab cell. Moreover, though a 15 percent deviation of structural parameters from the optimal spiral grating is applied, only a 5 percent decrease of the absorption is observed. This reveals that the performance of the proposed grating would tolerate large structural variations. Furthermore, the angular and polarization dependence on the absorption of the optimized cell is studied. For average polarizations, a small decrease of only 11 percent from the maximum absorption is observed within an incident angle ranging from −70 to 70 degrees. The results show promising application potentials of the biomimetic spiral grating in the solar cell.

  16. Rapid screening and identification of illicit drugs by IR absorption spectroscopy and gas chromatography

    Science.gov (United States)

    Mengali, Sandro; Liberatore, Nicola; Luciani, Domenico; Viola, Roberto; Cardinali, Gian Carlo; Elmi, Ivan; Poggi, Antonella; Zampolli, Stefano; Biavardi, Elisa; Dalcanale, Enrico; Bonadio, Federica; Delemont, Olivier; Esseiva, Pierre; Romolo, Francesco S.

    2013-01-01

    Analytical instruments based on InfraRed Absorption Spectroscopy (IRAS) and Gas Chromatography (GC) are today available only as bench-top instrumentation for forensic labs and bulk analysis. Within the 'DIRAC' project funded by the European Commission, we are developing an advanced portable sensor, that combines miniaturized GC as its key chemical separation tool, and IRAS in a Hollow Fiber (HF) as its key analytical tool, to detect and recognize illicit drugs and key precursors, as bulk and as traces. The HF-IRAS module essentially consists of a broadly tunable External Cavity (EC) Quantum Cascade Laser (QCL), thermo-electrically cooled MCT detectors, and an infrared hollow fiber at controlled temperature. The hollow fiber works as a miniaturized gas cell, that can be connected to the output of the GC column with minimal dead volumes. Indeed, the module has been coupled to GC columns of different internal diameter and stationary phase, and with a Vapour Phase Pre-concentrator (VPC) that selectively traps target chemicals from the air. The presentation will report the results of tests made with amphetamines and precursors, as pure substances, mixtures, and solutions. It will show that the sensor is capable of analyzing all the chemicals of interest, with limits of detection ranging from a few nanograms to about 100-200 ng. Furthermore, it is suitable to deal with vapours directly trapped from the headspace of a vessel, and with salts treated in a basic solution. When coupled to FAST GC columns, the module can analyze multi-components mixes in less than 5 minutes.

  17. Infrared absorption spectroscopy characterization of liquid-solid interfaces: The case of chiral modification of catalysts

    Science.gov (United States)

    Zaera, Francisco

    2018-03-01

    An overview is provided here of our work on the characterization of chiral modifiers for the bestowing of enantioselectivity to metal-based hydrogenation catalysts, with specific reference to the so-called Orito reaction. We start with a brief discussion of the use of infrared absorption spectroscopy (IR) for the characterization of chemical species at liquid-solid interfaces, describing the options available as well as the information that can be extracted from such experiments and the advantages and disadvantages associated with the technique. We then summarize the main results that we have reported to date from our IR study of the adsorption of cinchona alkaloids and related compounds from solutions onto platinum surfaces. Several observations are highlighted and placed in context in terms of the existing knowledge and their relevance to catalysis. Key conclusions include the uniqueness of the nature of the adsorbed species when in the presence of the solvent (versus when the uptake is done under vacuum, or versus the pure or dissolved molecules), the fact that each modifier adopts unique and distinct adsorption geometries on the surface and that those change with the concentration of the solution in ways that correlate well with the performance of the catalyst, the potential tendency of at least some of these chiral modifiers to bind to the surface primarily via the nitrogen atom of the amine group, not the aromatic ring as it is often assumed, and the observation that the ability of one modifier to dominate the catalytic chemistry in solutions containing mixtures of two or more of those is linked to their capacity for displacing each other from the surface, which in turn is determined by a balance between the strength of their binding to the surface and their solubility in the liquid solvent.

  18. Solution-Processed Environmentally Friendly Ag2S Colloidal Quantum Dot Solar Cells with Broad Spectral Absorption

    Directory of Open Access Journals (Sweden)

    Viktor A. Öberg

    2017-10-01

    Full Text Available A facile heat-up synthesis route is used to synthesize environmentally friendly Ag2S colloidal quantum dots (CQDs that are applied as light absorbing material in solid state p-i-n junction solar cell devices. The as-synthesized Ag2S CQDs have an average size of around 3.5 nm and exhibit broad light absorption covering ultraviolet, visible, and near infrared wavelength regions. The solar cell devices are constructed with a device architecture of FTO/TiO2/Ag2S CQDs/hole transport material (HTM /Au using a solution-processed approach. Different HTMs, N2,N2,N2′,N2′,N7,N7,N7′,N7′-octakis(4-methoxyphenyl-9,9′-spirobi(9H-fluorene-2,2′,7,7′ tetramine (spiro-OMeTAD, poly(3-hexylthiophene-2,5-diyl (P3HT, and poly((2,3-bis(3-octyloxyphenyl-5,8-quinoxalinediyl-2,5-thiophenediyl TQ1 are studied for maximizing the device photovoltaic performance. The solar cell device with P3HT as a hole transport material gives the highest performance and the solar cell exhibit broad spectral absorption. These results indicate that Ag2S CQD have high potential for utilization as environmentally friendly light absorbing materials for solar cell application and that the hole transport material is critical to maximize the solar cell photovoltaic performance.

  19. GaSb based lasers operating near 2.3 .mu.m for high resolution absorption spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Civiš, Svatopluk; Horká-Zelenková, Veronika; Šimeček, Tomislav; Hulicius, Eduard; Pangrác, Jiří; Oswald, Jiří; Petříček, Otto; Rouillard, C.; Alibert, C.; Werner, R.

    2005-01-01

    Roč. 61, - (2005), s. 3066-3069 ISSN 1386-1425 R&D Projects: GA AV ČR KSK1010104; GA AV ČR IAA4040104; GA MŠk OC 715.50 Institutional research plan: CEZ:AV0Z40400503; CEZ:AV0Z1010914 Keywords : laser diode * absorption spectroscopy * gas detection * methane Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.290, year: 2005

  20. System for time-resolved laser absorption spectroscopy and its application to high-power impulse magnetron sputtering

    Czech Academy of Sciences Publication Activity Database

    Adámek, Petr; Olejníček, Jiří; Hubička, Zdeněk; Čada, Martin; Kment, Štěpán; Kohout, Michal; Do, H.T.

    2017-01-01

    Roč. 88, č. 2 (2017), 1-8, č. článku 023105. ISSN 0034-6748 R&D Projects: GA TA ČR(CZ) TF01000084; GA ČR(CZ) GA15-00863S Institutional support: RVO:68378271 Keywords : plasma diagnostics * HiPIMS * time resolved measurement * laser absorption spectroscopy Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 1.515, year: 2016

  1. Vibrational spectroscopy of photosensitizer dyes for organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Perez Leon, C.

    2005-11-18

    Ruthenium(II) complexes containing polypyridyl ligands are intensely investigated as potential photosensitizers in organic solar cells. Of particular interest is their use in dye-sensitized solar cells based on nanocrystalline films of TiO{sub 2}. Functional groups of the dye allow for efficient anchoring on the semiconductor surface and promote the electronic communication between the donor orbital of the dye and the conduction band of the semiconductor. In the present work a new dye, [Ru(dcbpyH{sub 2}){sub 2}(bpy-TPA{sub 2})](PF6{sub )2}, and the well known (Bu{sub 4}N){sub 2}[Ru(dcbpyH){sub 2}(NCS){sub 2}] complex were spectroscopically characterized. The electronic transitions of both dyes showed solvatochromic shifts due to specific interactions of the ligands with the solvent molecules. The surface-enhanced Raman (SER) spectra of the dyes dissolved in water, ethanol, and acetonitrile were measured in silver and gold colloidal solutions. The results demonstrate that the dyes were adsorbed on the metallic nanoparticles in different ways for different solvents. It was also found that in the gold colloid, the aqueous solutions of both dyes did not produce any SERS signal, whereas in ethanolic solution the SERS effect was very weak. Deprotonation, H-bonding, and donor-acceptor interactions seem to determine these different behaviors. Our results indicate the important role of the charge transfer mechanism in SERS. The adsorption of the dye on two different TiO{sub 2} substrates, anatase paste films and anatase nanopowder, was also studied to clarify the role of the carboxylate groups in the anchoring process of the dyes on the semiconductor surface. The recorded spectra indicate a strong dependence of the anchoring configuration on the morphology of the semiconductor. (orig.)

  2. In situ optical absorption and reflection spectroscopy of doping CsCl crystal with Pb{sup 2+} ions

    Energy Technology Data Exchange (ETDEWEB)

    Kondo, S.; Amaya, K.; Saito, T. [Research Center for Development of Far-Infrared Region, Fukui University, Bunkyo, Fukui (Japan); Higuchi, S.; Asada, H.; Ishikane, M. [Department of Applied Physics, Faculty of Engineering, Fukui University, Bunkyo, Fukui (Japan)

    2001-12-03

    Behaviours of Pb{sup 2+} ions during thermal treatments of PbCl{sub 2}-deposited CsCl crystals have been observed in situ by optical absorption and reflection spectroscopy. In the early stages of the treatments, the Pb{sup 2+} ions take part in the formation of Cs{sub 4}PbCl{sub 6} crystallites near the surface of the CsCl crystals. The crystallites exhibit a novel absorption spectrum suggesting that the 6s and 6p states of the Pb{sup 2+} ions are strongly localized. On heavy annealing at a high temperature (673 K) followed by a rapid cooling to room temperature, the Pb{sup 2+} ions are uniformly dispersed throughout the CsCl crystals, exhibiting the absorption spectrum attributable to isolated Pb{sup 2+}-ion centres. (author)

  3. Local structure of LiCoO2 nanoparticles studied by Co K-edge x-ray absorption spectroscopy

    Science.gov (United States)

    Maugeri, L.; Iadecola, A.; Joseph, B.; Simonelli, L.; Olivi, L.; Okubo, M.; Honma, I.; Wadati, H.; Mizokawa, T.; Saini, N. L.

    2012-08-01

    We have studied the local structure of LiCoO2 nanoparticles by Co K-edge x-ray absorption spectroscopy as a function of particle size. Extended x-ray absorption fine structure data reveal substantial changes in the near neighbor distances and the associated mean square relative displacements with decreasing particle size. X-ray absorption near edge structure spectra show clear local geometrical changes with decreasing particle size, similar to those that appear in the charging (delithiation) process. The results suggest that the LiCoO2 nanoparticles are characterized by a large atomic disorder confined to the Co-O octahedra, similar to the distortions generated during the delithiation, and this disorder should be the primary limiting factor for a reversible diffusion of Li ions when nanoparticles of LiCoO2 are used as cathode material in rechargeable Li ion batteries.

  4. Local Structure Determination of Carbon/Nickel Ferrite Composite Nanofibers Probed by X-ray Absorption Spectroscopy.

    Science.gov (United States)

    Nilmoung, Sukunya; Kidkhunthod, Pinit; Maensiri, Santi

    2015-11-01

    Carbon/NiFe2O4 composite nanofibers have been successfully prepared by electrospinning method using a various concentration solution of Ni and Fe nitrates dispersed into polyacrylonitride (PAN) solution in N,N' dimethylformamide. The phase and mophology of PAN/NiFe2O4 composite samples were characterized and investigated by X-ray diffraction and scanning electron microscopy. The magnetic properties of the prepared samples were measured at ambient temperature by a vibrating sample magnetometer. It is found that all composite samples exhibit ferromagnetism. This could be local-structurally explained by the existed oxidation states of Ni2+ and Fe3+ in the samples. Moreover, local environments around Ni and Fe ions could be revealed by X-ray absorption spectroscopy (XAS) measurement including X-ray absorption near edge structure (XANES) and Extended X-ray absorption fine structure (EXAFS).

  5. Infrared Absorption Spectroscopy and Chemical Kinetics of Free Radicals. Final Performance Report, August 1, 1985--July 31, 1994

    Science.gov (United States)

    Curl, R. F.; Glass, G. P.

    1995-06-01

    This research was directed at the detection, monitoring, and study (by infrared absorption spectroscopy) of the chemical kinetic behavior of small free radical species thought to be important intermediates in combustion. The work typically progressed from the detection and analysis of the infrared spectrum of combustion radical to the utilization of the infrared spectrum thus obtained in the investigation of chemical kinetics of the radical species. The methodology employed was infrared kinetic spectroscopy. In this technique the radical is produced by UV flash photolysis using an excimer laser and then its transient infrared absorption is observed using a single frequency cw laser as the source of the infrared probe light. When the probe laser frequency is near the center of an absorption line of the radical produced by the flash, the transient infrared absorption rises rapidly and then decays as the radical reacts with the precursor or with substances introduced for the purpose of studying the reaction kinetics or with itself. The decay times observed in these studies varied from less than one microsecond to more than one millisecond. By choosing appropriate time windows after the flash and the average infrared detector signal in a window as data channels, the infrared spectrum of the radical may be obtained. By locking the infrared probe laser to the center of the absorption line and measuring the rate of decay of the transient infrared absorption signal as the chemical composition of the gas mixture is varied, the chemical kinetics of the radical may be investigated. In what follows the systems investigated and the results obtained are outlined.

  6. The origin of enhanced optical absorption in solar cells with metal nanoparticles embedded in the active layer

    KAUST Repository

    Lee, Jung-Yong

    2010-04-29

    We analyze the enhancement in optical absorption of an absorbing medium when spherical metal nanoparticles are embedded in it. Our analysis uses generalized Mie theory to calculate the absorbed optical power as a function of the distance from the metal nanoparticle. This analysis is used to evaluate the potential of enhancing optical absorption in thin-film solar cells by embedding spherical metal nanoparticles. We consider the trade-off between maximizing overall optical absorption and ensuring that a large fraction of the incident optical power is dissipated in the absorbing host medium rather than in the metal nanoparticle. We show that enhanced optical absorption results from strong scattering by the metal nanoparticle which locally enhances the optical electric fields. We also discuss the effect of a thin dielectric encapsulation of the metal nanoparticles. ©2010 Optical Society of America.

  7. Very high resolution UV and X-ray spectroscopy and imagery of solar active regions

    Science.gov (United States)

    Bruner, M.; Brown, W. A.; Haisch, B. M.

    1987-01-01

    A scientific investigation of the physics of the solar atmosphere, which uses the techniques of high resolution soft X-ray spectroscopy and high resolution UV imagery, is described. The experiments were conducted during a series of three sounding rocket flights. All three flights yielded excellent images in the UV range, showing unprecedented spatial resolution. The second flight recorded the X-ray spectrum of a solar flare, and the third that of an active region. A normal incidence multi-layer mirror was used during the third flight to make the first astronomical X-ray observations using this new technique.

  8. Comparison of ScaRaB, GOES 8, Aircraft, and Surface Observations of the Absorption of Solar Radiation by Clouds

    Science.gov (United States)

    Pope, Shelly K.; Valero, Francisco P. J.; Collins, William D.; Minnis, Patrick

    2002-01-01

    Data obtained by the Scanner for Radiation Budget (ScaRaB) instrument on the Meteor 3 satellite have been analyzed and compared to satellite (GOES 8), aircraft (Radiation Measurement System, RAMS), and surface (Baseline Solar Radiation Network (BSRN), Solar and Infrared Observations System (SIROS), and RAMS) measurements of irradiance obtained during the Atmospheric Radiation Measurements Enhanced Shortwave Experiment (ARESE). It is found that the ScaRaB data covering the period from March 1994 to February 1995 (the instrument's operational lifetime) indicate excess absorption of solar radiation by the cloudy atmosphere in agreement with previous aircraft, surface, and GOES 8 results. The full ScaRaB data set combined with BSRN and SIROS surface observations gives an average all-sky absorptance of 0.28. The GOES 8 data set combined with RAMS surface observations gives an average all-sky absorptance of 0.26. The aircraft data set (RAMS) gives a mean all-sky absorptance of 0.24 (for the column between 0.5 and 13 km).

  9. Micro-spectroscopy on silicon wafers and solar cells

    Directory of Open Access Journals (Sweden)

    Gundel Paul

    2011-01-01

    Full Text Available Abstract Micro-Raman (μRS and micro-photoluminescence spectroscopy (μPLS are demonstrated as valuable characterization techniques for fundamental research on silicon as well as for technological issues in the photovoltaic production. We measure the quantitative carrier recombination lifetime and the doping density with submicron resolution by μPLS and μRS. μPLS utilizes the carrier diffusion from a point excitation source and μRS the hole density-dependent Fano resonances of the first order Raman peak. This is demonstrated on micro defects in multicrystalline silicon. In comparison with the stress measurement by μRS, these measurements reveal the influence of stress on the recombination activity of metal precipitates. This can be attributed to the strong stress dependence of the carrier mobility (piezoresistance of silicon. With the aim of evaluating technological process steps, Fano resonances in μRS measurements are analyzed for the determination of the doping density and the carrier lifetime in selective emitters, laser fired doping structures, and back surface fields, while μPLS can show the micron-sized damage induced by the respective processes.

  10. Rhodanine dyes for dye-sensitized solar cells : spectroscopy, energy levels and photovoltaic performance.

    Science.gov (United States)

    Marinado, Tannia; Hagberg, Daniel P; Hedlund, Maria; Edvinsson, Tomas; Johansson, Erik M J; Boschloo, Gerrit; Rensmo, Håkan; Brinck, Tore; Sun, Licheng; Hagfeldt, Anders

    2009-01-07

    Three new sensitizers for photoelectrochemical solar cells were synthesized consisting of a triphenylamine donor, a rhodanine-3-acetic acid acceptor and a polyene connection. The conjugation length was systematically increased, which resulted in two effects: first, it led to a red-shift of the optical absorption of the dyes, resulting in an improved spectral overlap with the solar spectrum. Secondly, the oxidation potential decreased systematically. The excited state levels were, however, calculated to be nearly stationary. The experimental trends were in excellent agreement with density functional theory (DFT) computations. The photovoltaic performance of this set of dyes as sensitizers in mesoporous TiO2 solar cells was investigated using electrolytes containing the iodide/triiodide redox couple. The dye with the best absorption characteristics showed the poorest solar cell efficiency, due to losses by recombination of electrons in TiO2 with triiodide. Addition of 4-tert butylpyridine to the electrolyte led to a strongly reduced photocurrent for all dyes due to a reduced electron injection efficiency, caused by a 0.15 V negative shift of the TiO2 conduction band potential.

  11. Source brightness fluctuation correction of solar absorption fourier transform mid infrared spectra

    Directory of Open Access Journals (Sweden)

    T. Ridder

    2011-06-01

    Full Text Available The precision and accuracy of trace gas observations using solar absorption Fourier Transform infrared spectrometry depend on the stability of the light source. Fluctuations in the source brightness, however, cannot always be avoided. Current correction schemes, which calculate a corrected interferogram as the ratio of the raw DC interferogram and a smoothed DC interferogram, are applicable only to near infrared measurements. Spectra in the mid infrared spectral region below 2000 cm−1 are generally considered uncorrectable, if they are measured with a MCT detector. Such measurements introduce an unknown offset to MCT interferograms, which prevents the established source brightness fluctuation correction. This problem can be overcome by a determination of the offset using the modulation efficiency of the instrument. With known modulation efficiency the offset can be calculated, and the source brightness correction can be performed on the basis of offset-corrected interferograms. We present a source brightness fluctuation correction method which performs the smoothing of the raw DC interferogram in the interferogram domain by an application of a running mean instead of high-pass filtering the corresponding spectrum after Fourier transformation of the raw DC interferogram. This smoothing can be performed with the onboard software of commercial instruments. The improvement of MCT spectra and subsequent ozone profile and total column retrievals is demonstrated. Application to InSb interferograms in the near infrared spectral region proves the equivalence with the established correction scheme.

  12. Multiphoton Absorption Order of CsPbBr3 As Determined by Wavelength-Dependent Nonlinear Optical Spectroscopy.

    Science.gov (United States)

    Saouma, Felix O; Stoumpos, Constantinos C; Kanatzidis, Mercouri G; Kim, Yong Soo; Jang, Joon I

    2017-10-05

    CsPbBr 3 is a direct-gap semiconductor where optical absorption takes place across the fundamental bandgap, but this all-inorganic halide perovskite typically exhibits above-bandgap emission when excited over an energy level, lying above the conduction-band minimum. We probe this bandgap anomaly using wavelength-dependent multiphoton absorption spectroscopy and find that the fundamental gap is strictly two-photon forbidden, rendering it three-photon absorption (3PA) active. Instead, two-photon absorption (2PA) commences when the two-photon energy is resonant with the optical gap, associated with the level causing the anomaly. We determine absolute nonlinear optical dispersion over this 3PA-2PA region, which can be explained by two-band models in terms of the optical gap. The polarization dependence of 3PA and 2PA is also measured and explained by the relevant selection rules. CsPbBr 3 is highly luminescent under multiphoton absorption at room temperature with marked polarization and wavelength dependence at the 3PA-2PA crossover and therefore has potential for nonlinear optical applications.

  13. SPECIES DETERMINATION OF ORGANOMETALLIC COMPOUNDS USING ZEEMAN ATOMIC ABSORPTION SPECTROSCOPY WITH LIQUID CHROMATOGRAPHY

    Energy Technology Data Exchange (ETDEWEB)

    Koizumi, H.; Hadeishi, T.; McLaughlin, R.

    1978-01-01

    Over the past several years we have devised and expanded the capabilities of Zeeman atomic absorption spectroscopy (ZAA). Using this technique, trace elements in a complex matrix can be directly analyzed with high accuracy even when there is only one atom of interest contained in several million atoms of the host material. Quantities in the nanogram, or in some cases picogram, range can be determined within IS seconds for more than 30 elements. Because of its high selectivity and high sensitivity, ZAA can be used as a new technique for organometallic species determination by interfacing with a high pressure liquid chromatograph (HPLC). The HPLC separates various molecular species. Different kinds of mobil solvents can be directly introduced in the ZAA detection system; even organic solvents or high concentration salt solutions. Then, organometallic species in the ppb range are separately detected according to their retention times. This technique has a much larger field of application than HPLC coupled with conventional AA. The advantages of the ZAA technique are described in a recent publication. In this case, a steady magnetic field at 11 kgauss is applied to the sample vapor perpendicular to the incident light beam. The difference in absorption of the polarized constituents P{perpendicular} and P{parallel} is proportional to the atomic density, but is not affected by the various kind of spectral interferences caused by thermal decomposition of the eluants. The recently developed HPLC technique has many advantages over gas chromatography. Nonvolatile, polar, thermally unstable molecules or high molecular weight compounds can be separated. In the present system, the main requirement is that the solute be soluble in the mobile solvent. A demonstration of the operation of this system is provided by the analysis of a mixture of vitamin B12 and Co(No{sub 3}){sub 2}. As shown in Figure 1, vitamin B12 has a Co in its functional center. Sample 1 contained Co of 0

  14. Light trapping in thin-film solar cells measured by Raman spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Ledinský, Martin; Moulin, E.; Bugnon, G.; Ganzerová, Kristína; Vetushka, Aliaksi; Meillaud, F.; Fejfar, Antonín; Ballif, C.

    2014-01-01

    Roč. 105, č. 11 (2014), "111106-1"-"111106-4" ISSN 0003-6951 R&D Projects: GA ČR GA14-15357S; GA MŠk(CZ) LM2011026; GA MŠk 7E12029 EU Projects: European Commission(XE) 283501 - FAST TRACK Institutional support: RVO:68378271 Keywords : light trapping * microcrystalline silicon * thin film solar cell * Raman spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.302, year: 2014

  15. Impedance spectroscopy characterisation of highly efficient silicon solar cells under different light illumination intensities

    OpenAIRE

    Mora Seró, Iván; García Belmonte, Germà; Pérez Boix, Pablo; Vázquez, Miguel A.; Bisquert, Juan

    2009-01-01

    Highly efficient silicon solar cells have been characterised by impedance spectroscopy and current–potential characteristic in the dark and with different illumination intensities. For each illumination the impedance behaviour has been analysed at different applied bias potentials, in the forward and reverse region, comparing the results with the current–potential characteristic. Different cell parameters, as series and parallel resistances, capacitance, diode factor, minority carrier lifetim...

  16. Accounting for Interference, Scattering, and Electrode Absorption to Make Accurate Internal Quantum Efficiency Measurements in Organic and Other Thin Solar Cells

    KAUST Repository

    Burkhard, George F.

    2010-05-31

    Accurately measuring internal quantum efficiency requires knowledge of absorption in the active layer of a solar cell. The experimentally accessible total absorption includes significant contributions from the electrodes and other nonactive layers. We suggest a straightforward method for calculating the active layer contribution that minimizes error by subtracting optically-modeled electrode absorption from experimentally measured total absorption. (Figure Presented) © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. X-ray absorption spectroscopy of GeO2 glass to 64 GPa

    International Nuclear Information System (INIS)

    Hong, Xinguo; Newville, Matthew; Sutton, Stephen R; Rivers, Mark L; Duffy, Thomas S

    2014-01-01

    The structural behavior of GeO 2 glass has been investigated up to 64 GPa using results from x-ray absorption spectroscopy in a diamond anvil cell combined with previously reported density measurements. The difference between the nearest Ge–O distances of glassy and rutile-type GeO 2 disappears at the Ge–O distance maximum at 20 GPa, indicating completion of the tetrahedral–octahedral transition in GeO 2 glass. The mean-square displacement σ 2 of the Ge–O distance in the first Ge–O shell increases progressively to a maximum at 10 GPa, followed by a substantial reduction at higher pressures. The octahedral glass is, as expected, less dense and has a higher compressibility than the corresponding crystalline phase, but the differences in Ge–O distance and density between the glass and the crystals are gradually eliminated over the 20–40 GPa pressure range. Above 40 GPa, GeO 2 forms a dense octahedral glass with a compressibility similar to that of the corresponding crystalline phase (α-PbO 2 type). The EXAFS and XANES spectra show evidence for subtle changes in the dense glass continuing to occur at these high pressures. The Ge–O bond distance shows little change between 45–64 GPa, and this may reflect a balance between bond shortening and a gradual coordination number increase with compression. The density of the glass is similar to that of the α–PbO 2 -type phase, but the Ge–O distance is longer and is close to that in the higher-coordination pyrite-type phase which is stable above ∼60 GPa. The density data provide evidence for a possible discontinuity and change in compressibility at 40–45 GPa, but there are no major changes in the corresponding EXAFS spectra. A pyrite-type local structural model for the glass can provide a reasonable fitting to the XAFS spectra at 64 GPa. (paper)

  18. Synchrotron-based X-ray absorption spectroscopy for art conservation: looking back and looking forward.

    Science.gov (United States)

    Cotte, Marine; Susini, Jean; Dik, Joris; Janssens, Koen

    2010-06-15

    A variety of analytical techniques augmented by the use of synchrotron radiation (SR), such as X-ray fluorescence (SR-XRF) and X-ray diffraction (SR-XRD), are now readily available, and they differ little, conceptually, from their common laboratory counterparts. Because of numerous advantages afforded by SR-based techniques over benchtop versions, however, SR methods have become popular with archaeologists, art historians, curators, and other researchers in the field of cultural heritage (CH). Although the CH community now commonly uses both SR-XRF and SR-XRD, the use of synchrotron-based X-ray absorption spectroscopy (SR-XAS) techniques remains marginal, mostly because CH specialists rarely interact with SR physicists. In this Account, we examine the basic principles and capabilities of XAS techniques in art preservation. XAS techniques offer a combination of features particularly well-suited for the chemical analysis of works of art. The methods are noninvasive, have low detection limits, afford high lateral resolution, and provide exceptional chemical sensitivity. These characteristics are highly desirable for the chemical characterization of precious, heterogeneous, and complex materials. In particular, the chemical mapping capability, with high spatial resolution that provides information about local composition and chemical states, even for trace elements, is a unique asset. The chemistry involved in both the object's history (that is, during fabrication) and future (that is, during preservation and restoration treatments) can be addressed by XAS. On the one hand, many studies seek to explain optical effects occurring in historical glasses or ceramics by probing the molecular environment of relevant chromophores. Hence, XAS can provide insight into craft skills that were mastered years, decades, or centuries ago but were lost over the course of time. On the other hand, XAS can also be used to characterize unwanted reactions, which are then considered

  19. X-ray absorption spectroscopy on high-temperature superconductors and related compounds

    International Nuclear Information System (INIS)

    Pellegrin, E.J.H.A.

    1995-07-01

    The electronic structure of the cuprate high-temperature superconductors La 2-x Sr x CuO 4+δ , Tl 2 Ba 2 CaCu 2 O 8 and Tl 2 Ba 2 Ca 2 Cu 3 O 10 has been investigated using polarization-dependent near-edge X-ray absorption fine structure spectroscopy (NEXAFS). In addition, La 2-x Sr x NiO 4+δ has been included in the actual study as an isostructural analogue to the La 2-x Sr x CuO 4+δ system. It appears that the electronic structure of these compounds corresponds to that of a p-type doped charge-transfer insulator including electron-electron interactions on the Cu(Ni) sites and a strong hybridization between Cu(Ni) and O atoms. It is concluded that the low-energy excitations in these compounds can be described on the basis of an effective one-band Mott-Hubbard model. The polarization-dependence of the above spectra gives evidence for the strong in-plane character of the intrinsic and the doped holes. The small amount and the doping-dependence of the out-of-plane character of these charge carriers rule out models for a microscopic mechanism of superconductivity based on a large amount of hole states in the corresponding Apex-O2p z /Cu3d 3z 2 -r 2 orbitals. On the other hand, the reduction of this anisotropy in the overdoped compounds together with similar findings in the macroscopic properties seems to indicate a detrimental influence of non-planar orbitals on the superconducting properties. The differences in the energetic ordering and atomic character of the states close to the Fermi level between the undoped compounds La 2 CuO 4+δ , La 2 NiO 4+δ , and NiO have been determined from the NEXAFS data. It is found that these differences can be explained by the different size of the tetragonal crystal field splitting E Z compared to that of the Hund's rule interaction J H in these systems. This gives evidence for the high-spin d 8 ground state of the undoped nickelates (i.e. J H >E Z ). It is suggested that the polarons in La 2-x Sr x NiO 4+δ can be seen as non

  20. Fourier Transform Absorption Spectroscopy of C_3 in the ν_3 Antisymmetric Stretch Mode Region

    Science.gov (United States)

    Vervloet, Michel; Martin-Drumel, Marie-Aline; Tokaryk, Dennis W.; Pirali, Olivier

    2017-06-01

    The C_3 molecule has been detected in a variety of astrophysical objects thanks to the well-known 4050 Å (A^1Π_u-X^1Σ ^+ _g) electronic transition as well as the two IR active modes of the electronic ground state: ν_2 (˜ 63.42 cm^{-1}) and ν_3 (˜ 2040.02 cm^{-1}). Previous laboratory data in the ν_3 region, obtained using diode laser spectroscopy and the photolysis of allene to produce C_3, permitted measurement of the fundamental (0,0,1)Σ-(0,0,0)Σ as well as the hot bands: (0,1,1)Π-(0,1,0)Π; (0,2,1)Σ-(0,2,0)Σ; (0,2,1)Δ-(0,2,0)Δ and provided insights on the anharmonicity of the (0,nν_2,1) vibrational pattern. We have recorded the absorption spectrum of C_3 in the 1800-2100 cm^{-1} region (at a resolution of 0.003 cm^{-1}) using the Bruker IFS 125 Fourier Transform spectrometer at the AILES beamline of Synchrotron SOLEIL. C_3 was produced in a DC discharge of methane heavily diluted in helium. The rovibrational temperature of C_3 produced in our discharge is noticeably higher than in Ref. [4], which allowed us to extend measurements to higher J values. More interestingly, we assigned new hot bands involving higher quanta of the ν_2 bending states: (0,nν_2,1) with n ranging from 0 to 5. Despite the absence of Q branches for these bands, which results in a possible ambiguous J-assignment of P and R lines, the large variety of data considered in this work, in addition to our experimental data and including observations of comet spectra, allows confident assignments. L. Gausset, G. Herzberg, A. Lagerqvist, B. Rosen, Astrophysical Journal, 45-81 (1965); T. F. Giesen et al., The Astrophysical Journal, 551, L181-L184 (2001) K. W. Hinkle, J. J. Keady, P. F. Bernath, Science, 241, 1319-1322 (1988) K. Kawaguchi et al., J. Chem. Phys., 91, 1953-1957 (1989)

  1. In situ analyses of Ag speciation in tissues of cucumber and wheat using synchrotron-based X-ray absorption spectroscopy

    Data.gov (United States)

    U.S. Environmental Protection Agency — In situ analyses of Ag speciation in tissues of cucumber and wheat using synchrotron-based X-ray absorption spectroscopy showing spectral fitting and linear...

  2. Estimation of lead, cadmium and nickel content by means of Atomic Absorption Spectroscopy in dry fruit bodies of some macromycetes growing in Poland. II.

    Directory of Open Access Journals (Sweden)

    Jan Grzybek

    2014-08-01

    Full Text Available The content of lead, cadmium, and nickel in dry fruit bodies of 34 species of macromyoetes collected in Poland from 72 natural babitats by means of Atomic Absorption Spectroscopy (AAS was estimated.

  3. X-ray absorption spectroscopy of PbMoO 4 single crystals

    Indian Academy of Sciences (India)

    X-ray absorption spectra of PbMoO4 (LMO) crystals have been investigated for the first time in literature. The measurements have been carried out at Mo absorption edge at the dispersive EXAFS beamline (BL-8) of INDUS-2 Synchrotron facility at Indore, India. The optics of the beamline was set to obtain a band of 2000 eV ...

  4. Open cycle liquid desiccant dehumidifier and hybrid solar/electric absorption refrigeration system. Annual report, January 1993--December 1993. Calendar year 1993

    Energy Technology Data Exchange (ETDEWEB)

    Nimmo, B.G.; Thornbloom, M.D.

    1995-04-01

    This annual report presents work performed during calendar year 1993 by the Florida Solar Energy Center under contract to the US Department of Energy. Two distinctively different solar powered indoor climate control systems were analyzed: the open cycle liquid desiccant dehumidifier, and an improved efficiency absorption system which may be fired by flat plate solar collectors. Both tasks represent new directions relative to prior FSEC research in Solar Cooling and Dehumidification.

  5. Structural investigations of LiFePO4 electrodes and in situ studies by Fe X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Deb, Aniruddha; Bergmann, Uwe; Cramer, S.P.; Cairns, Elton J.

    2005-01-01

    Fe K-edge X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) have been performed on electrodes containing LiFePO 4 to determine the local atomic and electronic structure and their stability with electrochemical cycling. A versatile electrochemical in situ cell has been constructed for long-term soft and hard X-ray experiments for the structural investigation on battery electrodes during the lithium-insertion/extraction processes. The device is used here for an X-ray absorption spectroscopic study of lithium insertion/extraction in a LiFePO 4 electrode, where the electrode contained about 7.7 mg of LiFePO 4 on a 20 μm thick Al-foil. Fe K-edge X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) have been performed on this electrode to determine the local atomic and electronic structure and their stability with electrochemical cycling. The initial state (LiFePO 4 ) showed iron to be in the Fe 2+ state corresponding to the initial state (0.0 mAh) of the cell, whereas in the delithiated state (FePO 4 ) iron was found to be in the Fe 3+ state corresponding to the final charged state (3 mAh). XANES region of the XAS spectra revealed a high spin configuration for the two states (Fe (II), d 6 and Fe (III), d 5 ). The results confirm that the olivine structure of the LiFePO 4 and FePO 4 is retained by the electrodes in agreement with the XRD observations reported previously. These results confirm that LiFePO 4 cathode material retains good structural short-range order leading to superior cycling capability

  6. Ultra-fast X-ray absorption spectroscopy for the study of matter in transient regime; Spectroscopie d'absorption ultra-rapide de rayonnement X pour l'etude de la matiere en regime transitoire

    Energy Technology Data Exchange (ETDEWEB)

    Lecherbourg, L

    2007-12-15

    In this work, we study the physics of dense matter, plasmas or solids, using X-ray absorption spectroscopy. Through the use of sources produced by laser-matter interaction, we have measured the absorption spectra of aluminum and bromine plasmas, as well as those of vanadium dioxide (VO{sub 2}). The measurement of absorption coefficients allows us to probe the dense matter and to study its properties. The experiments are carried out following the same principle: they use the same experimental set-up, called pump-probe. When the matter is dense, the absorption properties of an atom are modified by the surrounding environment. In a plasma, it is mainly the bound- bound transitions which are altered: the shapes of those spectral rays are modified. In a solid, the position of the neighbouring atoms in relation to the absorbing atom modify the structure of absorption levels (bound-free transition). The study of this structure allows us to measure the parameters of the material, and provides information such as the state of the electronic band or the interatomic gaps. The experiments carried out at the LULI have allowed us to probe plasmas in the relatively unknown regime of the Warm Dense Matter. One of the key parameters is that the plasma is characterised independently (FDI diagnostic). It allows for a better comparison of the measured absorption against a calculation made with the numerical model OPA-S. The experiments carried out at INRS have led to the realisation of an experimental system having the characteristics which allow the study of the dynamics of solids showing ultra-fast phase transition. For those experiments, we have used vanadium dioxide as a model system allowing us to test the feasibility of the method. (author)

  7. From Semi- to Full-Two-Dimensional Conjugated Side-Chain Design: A Way toward Comprehensive Solar Energy Absorption

    Energy Technology Data Exchange (ETDEWEB)

    Chao, Pengjie [Department; School; Wang, Huan [Department; Qu, Shiwei [Department; Mo, Daize [Department; Meng, Hong [School; Chen, Wei [Materials; Institute; He, Feng [Department

    2017-12-05

    Two polymers with fully two-dimensional (2D) conjugated side chains, 2D-PTB-Th and 2D-PTB-TTh, were synthesized and characterized through simultaneously integrating the 2D-TT and the 2D-BDT monomers onto the polymer backbone. Resulting from the synergistic effect from the conjugated side chains on both monomers, the two polymers showed remarkably efficient absorption of the sunlight and improved pi-pi intermolecular interactions for efficient charge carrier transport. The optimized bulk heterojunction device based on 2D-PTB-Th and PC71BM shows a higher PCE of 9.13% compared to PTB7-Th with a PCE of 8.26%, which corresponds to an approximately 10% improvement in solar energy conversion. The fully 2D-conjugated side-chain concept reported here developed a new molecular design strategy for polymer materials with enhanced sunlight absorption and efficient solar energy conversion.

  8. Highly doped semiconductor plasmonic nanoantenna arrays for polarization selective broadband surface-enhanced infrared absorption spectroscopy of vanillin

    Science.gov (United States)

    Barho, Franziska B.; Gonzalez-Posada, Fernando; Milla, Maria-Jose; Bomers, Mario; Cerutti, Laurent; Tournié, Eric; Taliercio, Thierry

    2017-11-01

    Tailored plasmonic nanoantennas are needed for diverse applications, among those sensing. Surface-enhanced infrared absorption (SEIRA) spectroscopy using adapted nanoantenna substrates is an efficient technique for the selective detection of molecules by their vibrational spectra, even in small quantity. Highly doped semiconductors have been proposed as innovative materials for plasmonics, especially for more flexibility concerning the targeted spectral range. Here, we report on rectangular-shaped, highly Si-doped InAsSb nanoantennas sustaining polarization switchable longitudinal and transverse plasmonic resonances in the mid-infrared. For small array periodicities, the highest reflectance intensity is obtained. Large periodicities can be used to combine localized surface plasmon resonances (SPR) with array resonances, as shown in electromagnetic calculations. The nanoantenna arrays can be efficiently used for broadband SEIRA spectroscopy, exploiting the spectral overlap between the large longitudinal or transverse plasmonic resonances and narrow infrared active absorption features of an analyte molecule. We demonstrate an increase of the vibrational line intensity up to a factor of 5.7 of infrared-active absorption features of vanillin in the fingerprint spectral region, yielding enhancement factors of three to four orders of magnitude. Moreover, an optimized readout for SPR sensing is proposed based on slightly overlapping longitudinal and transverse localized SPR.

  9. Highly doped semiconductor plasmonic nanoantenna arrays for polarization selective broadband surface-enhanced infrared absorption spectroscopy of vanillin

    Directory of Open Access Journals (Sweden)

    Barho Franziska B.

    2017-11-01

    Full Text Available Tailored plasmonic nanoantennas are needed for diverse applications, among those sensing. Surface-enhanced infrared absorption (SEIRA spectroscopy using adapted nanoantenna substrates is an efficient technique for the selective detection of molecules by their vibrational spectra, even in small quantity. Highly doped semiconductors have been proposed as innovative materials for plasmonics, especially for more flexibility concerning the targeted spectral range. Here, we report on rectangular-shaped, highly Si-doped InAsSb nanoantennas sustaining polarization switchable longitudinal and transverse plasmonic resonances in the mid-infrared. For small array periodicities, the highest reflectance intensity is obtained. Large periodicities can be used to combine localized surface plasmon resonances (SPR with array resonances, as shown in electromagnetic calculations. The nanoantenna arrays can be efficiently used for broadband SEIRA spectroscopy, exploiting the spectral overlap between the large longitudinal or transverse plasmonic resonances and narrow infrared active absorption features of an analyte molecule. We demonstrate an increase of the vibrational line intensity up to a factor of 5.7 of infrared-active absorption features of vanillin in the fingerprint spectral region, yielding enhancement factors of three to four orders of magnitude. Moreover, an optimized readout for SPR sensing is proposed based on slightly overlapping longitudinal and transverse localized SPR.

  10. Detection of hydrogen peroxide based on long-path absorption spectroscopy using a CW EC-QCL

    Science.gov (United States)

    Sanchez, N. P.; Yu, Y.; Dong, L.; Griffin, R.; Tittel, F. K.

    2016-02-01

    A sensor system based on a CW EC-QCL (mode-hop-free range 1225-1285 cm-1) coupled with long-path absorption spectroscopy was developed for the monitoring of gas-phase hydrogen peroxide (H2O2) using an interference-free absorption line located at 1234.055 cm-1. Wavelength modulation spectroscopy (WMS) with second harmonic detection was implemented for data processing. Optimum levels of pressure and modulation amplitude of the sensor system led to a minimum detection limit (MDL) of 25 ppb using an integration time of 280 sec. The selected absorption line for H2O2, which exhibits no interference from H2O, makes this sensor system suitable for sensitive and selective monitoring of H2O2 levels in decontamination and sterilization processes based on Vapor Phase Hydrogen Peroxide (VPHP) units, in which a mixture of H2O and H2O2 is generated. Furthermore, continuous realtime monitoring of H2O2 concentrations in industrial facilities employing this species can be achieved with this sensing system in order to evaluate average permissible exposure levels (PELs) and potential exceedances of guidelines established by the US Occupational Safety and Health Administration for H2O2.

  11. Characterization of dissolved organic matter in Dongjianghu Lake by UV-visible absorption spectroscopy with multivariate analysis.

    Science.gov (United States)

    Zhu, Yanzhong; Song, Yonghui; Yu, Huibin; Liu, Ruixia; Liu, Lusan; Lv, Chunjian

    2017-08-08

    UV-visible absorption spectroscopy coupled with principal component analysis (PCA) and hierarchical cluster analysis (HCA) was applied to characterize spectroscopic components, detect latent factors, and investigate spatial variations of dissolved organic matter (DOM) in a large-scale lake. Twelve surface water samples were collected from Dongjianghu Lake in China. DOM contained lignin and quinine moieties, carboxylic acid, microbial products, and aromatic and alkyl groups, which in the northern part of the lake was largely different from the southern part. Fifteen spectroscopic indices were deduced from the absorption spectra to indicate molecular weight or humification degree of DOM. The northern part of the lake presented the smaller molecular weight or the lower humification degree of DOM than the southern part. E 2/4 , E 3/4 , E 2/3 , and S 2 were latent factors of characterizing the molecular weight of DOM, while E 2/5 , E 3/5 , E 2/6 , E 4/5 , E 3/6 , and A 2/1 were latent factors of evaluating the humification degree of DOM. The UV-visible absorption spectroscopy combined with PCA and HCA may not only characterize DOM fractions of lakes, but may be transferred to other types of waterscape.

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

    Science.gov (United States)

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

    2017-06-01

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

  13. The Impacts of Different Expansion Modes on Performance of Small Solar Energy Firms: Perspectives of Absorptive Capacity

    OpenAIRE

    Chen, Hsing Hung; Shen, Tao; Xu, Xin-long; Ma, Chao

    2013-01-01

    The characteristics of firm’s expansion by differentiated products and diversified products are quite different. However, the study employing absorptive capacity to examine the impacts of different modes of expansion on performance of small solar energy firms has never been discussed before. Then, a conceptual model to analyze the tension between strategies and corporate performance is proposed to filling the vacancy. After practical investigation, the results show that stronger organizationa...

  14. Optical and structural properties of plasma-treated Cordyceps bassiana spores as studied by circular dichroism, absorption, and fluorescence spectroscopy

    Science.gov (United States)

    Lee, Geon Joon; Sim, Geon Bo; Choi, Eun Ha; Kwon, Young-Wan; Kim, Jun Young; Jang, Siun; Kim, Seong Hwan

    2015-01-01

    To understand the killing mechanism of fungal spores by plasma treatment, the optical, structural, and biological properties of the insect pathogenic fungus Cordyceps bassiana spores were studied. A nonthermal atmospheric-pressure plasma jet (APPJ) was used to treat the spores in aqueous solution. Optical emission spectra of the APPJ acquired in air indicated emission peaks corresponding to hydroxyl radicals and atomic oxygen. When the APPJ entered the aqueous solution, additional reactive species were derived from the interaction of plasma radicals with the aqueous solution. Fluorescence and absorption spectroscopy confirmed the generation of hydroxyl radicals and hydrogen peroxide in the plasma-activated water (PAW). Spore counting showed that plasma treatment significantly reduced spore viability. Absorption spectroscopy, circular dichroism (CD) spectroscopy, and agarose gel electrophoresis of the DNA extracted from plasma-treated spores showed a reduction in spore DNA content. The magnitude of the dip in the CD spectrum was lower in the plasma-treated spores than in the control, indicating that plasma treatment causes structural modifications and/or damage to cellular components. Tryptophan fluorescence intensity was lower in the plasma-treated spores than in the control, suggesting that plasma treatment modified cell wall proteins. Changes in spore viability and DNA content were attributed to structural modification of the cell wall by reactive species coming from the APPJ and the PAW. Our results provided evidence that the plasma radicals and the derived reactive species play critical roles in fungal spore inactivation.

  15. Optical and structural properties of plasma-treated Cordyceps bassiana spores as studied by circular dichroism, absorption, and fluorescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Geon Joon, E-mail: gjlee@kw.ac.kr; Sim, Geon Bo; Choi, Eun Ha [Plasma Bioscience Research Center/Department of Electrical and Biological Physics, Kwangwoon University, Seoul 139-701 (Korea, Republic of); Kwon, Young-Wan [KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 136-701 (Korea, Republic of); Kim, Jun Young; Jang, Siun; Kim, Seong Hwan, E-mail: piceae@naver.com [Department of Microbiology and Institute of Basic Sciences, Dankook University, Cheonan 330-714 (Korea, Republic of)

    2015-01-14

    To understand the killing mechanism of fungal spores by plasma treatment, the optical, structural, and biological properties of the insect pathogenic fungus Cordyceps bassiana spores were studied. A nonthermal atmospheric-pressure plasma jet (APPJ) was used to treat the spores in aqueous solution. Optical emission spectra of the APPJ acquired in air indicated emission peaks corresponding to hydroxyl radicals and atomic oxygen. When the APPJ entered the aqueous solution, additional reactive species were derived from the interaction of plasma radicals with the aqueous solution. Fluorescence and absorption spectroscopy confirmed the generation of hydroxyl radicals and hydrogen peroxide in the plasma-activated water (PAW). Spore counting showed that plasma treatment significantly reduced spore viability. Absorption spectroscopy, circular dichroism (CD) spectroscopy, and agarose gel electrophoresis of the DNA extracted from plasma-treated spores showed a reduction in spore DNA content. The magnitude of the dip in the CD spectrum was lower in the plasma-treated spores than in the control, indicating that plasma treatment causes structural modifications and/or damage to cellular components. Tryptophan fluorescence intensity was lower in the plasma-treated spores than in the control, suggesting that plasma treatment modified cell wall proteins. Changes in spore viability and DNA content were attributed to structural modification of the cell wall by reactive species coming from the APPJ and the PAW. Our results provided evidence that the plasma radicals and the derived reactive species play critical roles in fungal spore inactivation.

  16. Ultrafast Transient Absorption Spectroscopy Investigation of Photoinduced Dynamics in Novel Donor-Acceptor Core-Shell Nanostructures for Organic Photovoltaics

    Science.gov (United States)

    Strain, Jacob; Jamhawi, Abdelqader; Abeywickrama, Thulitha M.; Loomis, Wendy; Rathnayake, Hemali; Liu, Jinjun

    2016-06-01

    Novel donor-acceptor nanostructures were synthesized via covalent synthesis and/or UV cross-linking method. Their photoinduced dynamics were investigated with ultrafast transient absorption (TA) spectroscopy. These new nanostructures are made with the strategy in mind to reduce manufacturing steps in the process of fabricating an organic photovoltaic cell. By imitating the heterojunction interface within a fixed particle domain, several fabrication steps can be bypassed reducing cost and giving more applicability to other film deposition methods. Such applications include aerosol deposition and ink-jet printing. The systems that were studied by TA spectroscopy include PDIB core, PDIB-P3HT core-shell, and PDIB-PANT core-shell which range in size from 60 to 130 nm. Within the experimentally accessible spectra range there resides a region of ground state bleaching, stimulated emission, and excited-state absorption of both neutrals and anions. Control experiments have been carried out to assign these features. At high pump fluences the TA spectra of PDIB core alone also indicate an intramolecular charge separation. The TA spectroscopy results thus far suggest that the core-shells resemble the photoinduced dynamics of a standard film although the particles are dispersed in solution, which indicates the desired outcome of the work.

  17. X-ray absorption spectroscopy using a self-seeded soft X-ray free-electron laser

    Energy Technology Data Exchange (ETDEWEB)

    Kroll, Thomas; Kern, Jan; Kubin, Markus; Ratner, Daniel; Gul, Sheraz; Fuller, Franklin D.; Löchel, Heike; Krzywinski, Jacek; Lutman, Alberto; Ding, Yuantao; Dakovski, Georgi L.; Moeller, Stefan; Turner, Joshua J.; Alonso-Mori, Roberto; Nordlund, Dennis L.; Rehanek, Jens; Weniger, Christian; Firsov, Alexander; Brzhezinskaya, Maria; Chatterjee, Ruchira; Lassalle-Kaiser, Benedikt; Sierra, Raymond G.; Laksmono, Hartawan; Hill, Ethan; Borovik, Andrew; Erko, Alexei; Föhlisch, Alexander; Mitzner, Rolf; Yachandra, Vittal K.; Yano, Junko; Wernet, Philippe; Bergmann, Uwe

    2016-01-01

    © 2016 Optical Society of America. X-ray free electron lasers (XFELs) enable unprecedented new ways to study the electronic structure and dynamics of transition metal systems. L-edge absorption spectroscopy is a powerful technique for such studies and the feasibility of this method at XFELs for solutions and solids has been demonstrated. However, the required x-ray bandwidth is an order of magnitude narrower than that of self-amplified spontaneous emission (SASE), and additional monochromatization is needed. Here we compare L-edge x-ray absorption spectroscopy (XAS) of a prototypical transition metal system based on monochromatizing the SASE radiation of the linac coherent light source (LCLS) with a new technique based on self-seeding of LCLS. We demonstrate how L-edge XAS can be performed using the self-seeding scheme without the need of an additional beam line monochromator. We show how the spectral shape and pulse energy depend on the undulator setup and how this affects the x-ray spectroscopy measurements.

  18. Water vapor concentration measurement in singlet oxygen generator by using emission spectroscopy method and absorption at 1392nm

    Science.gov (United States)

    Zhao, Weili; Wang, Zengqiang; Fang, Benjie; Li, Qingwei; Jin, Yuqi; Sang, Fengting

    2005-12-01

    By using emission spectroscopy method and absorption at 1392nm, partial water pressure at the exit of a square pipe-array jet-type singlet oxygen generator (SPJSOG) for chemical oxygen-iodine laser (COIL) was measured. The water vapor fraction was calculated from the partial water pressure in the diagnostic cell when we assumed the water vapor fraction in the diagnostic cell is the same as that in the generator. The results from the two methods showed that the water vapor concentration is less than 0.08 in this SPJSOG during normal operation. The water vapor fraction decreases with the increasing of the pressure in the generator and rises with the increasing of buffer gas flow rate and the basic hydrogen peroxide (BHP) temperature in the case of constant chlorine flow rate. Measurements showed that the change of water vapor fraction due to BHP temperature could be ignored during normal operation. It is indicated that the gas flow velocity is the main reason that affects on the water vapor fraction in COIL. It is proved that the emission spectroscopy method is one of the simple and convenient ways to measure the water vapor concentration in singlet oxygen generator (SOG), especially in real time measurements. But absorption spectroscopy method, as a direct measurement, can give the more factual results of the water concentration.

  19. Resonance absorption spectroscopy for laser-ablated lanthanide atom. (1) Optimized experimental conditions for isotope-selective absorption of gadolinium (Contract research)

    International Nuclear Information System (INIS)

    Miyabe, Masabumi; Oba, Masaki; Iimura, Hideki; Akaoka, Katsuaki; Maruyama, Yoichiro; Wakaida, Ikuo; Watanabe, Kazuo

    2008-06-01

    For remote isotope analysis of low-decontaminated TRU fuel, we are developing an analytical technique on the basis of the resonance absorption spectroscopy for the laser-ablation plume. To improve isotopic selectivity and detection sensitivity of this technique, we measured absorption spectra of Gd atom with various plume production conditions (ablation laser intensity, ambient gas and its pressure) and observation conditions (transition, probe height from sample, observation timing). As a result, high resolution spectrum was obtained from the observation of slow component of the plume produced under low-pressure rare-gas ambient. The observed narrowest linewidth of about 0.85GHz was found to be close to the Doppler width estimated for Gd atom of room temperature. Furthermore, relaxation rate of higher meta-stable state was found to be higher than that of ground state, suggesting that use of the transition arising from ground state or lower meta-stable state is preferable for highly sensitive isotope analysis. (author)

  20. Inelastic electron scattering spectroscopy: a comparison of absorption and emission spectra

    International Nuclear Information System (INIS)

    Schnatterly, S.E.

    1984-01-01

    The operation of a high energy inelastic scattering spectrometer is briefly described. Measured absorption and emission spectra are fit to parameters in recently described models for insulators. Implications for model validity are discussed

  1. Perfect-absorption graphene metamaterials for surface-enhanced molecular fingerprint spectroscopy

    Science.gov (United States)

    Guo, Xiangdong; Hu, Hai; Liao, Baoxin; Zhu, Xing; Yang, Xiaoxia; Dai, Qing

    2018-05-01

    Graphene plasmon with extremely strong light confinement and tunable resonance frequency represents a promising surface-enhanced infrared absorption (SEIRA) sensing platform. However, plasmonic absorption is relatively weak (approximately 1%-9%) in monolayer graphene nanostructures, which would limit its sensitivity. Here, we theoretically propose a hybrid plasmon-metamaterial structure that can realize perfect absorption in graphene with a low carrier mobility of 1000 cm2 V-1 s-1. This structure combines a gold reflector and a gold grating to the graphene plasmon structures, which introduce interference effect and the lightning-rod effect, respectively, and largely enhance the coupling of light to graphene. The vibration signal of trace molecules can be enhanced up to 2000-fold at the hotspot of the perfect-absorption structure, enabling the SEIRA sensing to reach the molecular level. This hybrid metal-graphene structure provides a novel path to generate high sensitivity in nanoscale molecular recognition for numerous applications.

  2. Development and Ecological-Energy Comparative Analysis оf Vapor Compression and Solar Absorption Schemes of Air Conditioning Systems

    Directory of Open Access Journals (Sweden)

    Doroshenko A.V.

    2017-12-01

    Full Text Available The mission of the research included the following objectives: the development of new circuit decisions for the alternate refrigerating systems based on the use of an open absorptive circuit and on the use of solar energy for absorbent solution regeneration; an assessment of the energy and envi-ronmental characteristics of the developed systems; obtaining of the experimental data for an assess-ment of the principal capabilities of the proposed new solar air-conditioning systems. New principles for design of heat and mass transfer equipment in the version with a movable packing of heat exchange elements (fluidized bed packing "gas - liquid - solid body" placed in the packed bed were developed, which allows self-cleaning of the working surfaces and walls of the heat and mass transfer equipment HMT. This new solution, when working with outdoor air and solutions of absorbents, seems to be a fundamentally important condition for maintaining the working capacity of solar absorption systems. The new schemes of absorber with internal steam cooling allowing the improve-ment of the new scheme of the alternate refrigerating system were developed. Comparative analysis based on the methodology of the "Life Cycle Assessment" (LCA showed that new, developed solar systems provide the considerable decrease in energy consumption, their use leads to the decrease of exhaustion of natural resources, influences less global climate change.

  3. The Impacts of Different Expansion Modes on Performance of Small Solar Energy Firms: Perspectives of Absorptive Capacity

    Directory of Open Access Journals (Sweden)

    Hsing Hung Chen

    2013-01-01

    Full Text Available The characteristics of firm’s expansion by differentiated products and diversified products are quite different. However, the study employing absorptive capacity to examine the impacts of different modes of expansion on performance of small solar energy firms has never been discussed before. Then, a conceptual model to analyze the tension between strategies and corporate performance is proposed to filling the vacancy. After practical investigation, the results show that stronger organizational institutions help small solar energy firms expanded by differentiated products increase consistency between strategies and corporate performance; oppositely, stronger working attitudes with weak management controls help small solar energy firms expanded by diversified products reduce variance between strategies and corporate performance.

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

    Science.gov (United States)

    Llorens, Isabelle; Lahera, Eric; Delnet, William; Proux, Olivier; Braillard, Aurélien; Hazemann, Jean-Louis; Prat, Alain; Testemale, Denis; Dermigny, Quentin; Gelebart, Frederic; Morand, Marc; Shukla, Abhay; Bardou, Nathalie; Ulrich, Olivier; Arnaud, Stéphan; Berar, Jean-François; Boudet, Nathalie; Caillot, Bernard; Chaurand, Perrine; Rose, Jérôme; Doelsch, Emmanuel; Martin, Philippe; Solari, Pier Lorenzo

    2012-06-01

    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.

  5. On-line Zeeman atomic-absorption spectroscopy for mercury analysis in oil-shale gases. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Girvin, D.C.; Fox, J.P.

    1981-03-01

    This report describes an instrumental technique to continuously measure total mercury in gas streams on a real-time basis. The technique utilizes Zeeman atomic absorption spectroscopy (ZAA) for on-line measurement of mercury in the presence of smoke, organic vapors, and oil mist which are typically present in offgases from oil shale processing plants. The accuracy of the ZAA background correction technique enables analytical measurement of mercury with up to 95% attenuation of the 2537A analytical line by broadband uv absorption. Furnaces with optical absorption tubes of different lengths are used depending upon the mercury concentration. Between 5 and 250 ppB (nanomoles Hg/mole of gas) of mercury in an 18-cm furnace is used. The instrumental response with this furnace is characterized by a detection limit (DL) of 2 ppB, a linear response up to 100 ppB, and a precision of +- 7% or better. In the 50 ppB to 1.6 ppM range, a furnace with a 5-cm optical absorption tube yields a DL of 10 ppB, a linear response up to 800 ppB, and a precision of +- 10% or better. Sample gas flow rates can be varied between 400 and 4000 scc/min for either furnace. 35 figures, 3 tables.

  6. Satellite monitoring of different vegetation types by differential optical absorption spectroscopy (DOAS in the red spectral range

    Directory of Open Access Journals (Sweden)

    T. Wagner

    2007-01-01

    Full Text Available A new method for the satellite remote sensing of different types of vegetation and ocean colour is presented. In contrast to existing algorithms relying on the strong change of the reflectivity in the red and near infrared spectral region, our method analyses weak narrow-band (few nm reflectance structures (i.e. "fingerprint" structures of vegetation in the red spectral range. It is based on differential optical absorption spectroscopy (DOAS, which is usually applied for the analysis of atmospheric trace gas absorptions. Since the spectra of atmospheric absorption and vegetation reflectance are simultaneously included in the analysis, the effects of atmospheric absorptions are automatically corrected (in contrast to other algorithms. The inclusion of the vegetation spectra also significantly improves the results of the trace gas retrieval. The global maps of the results illustrate the seasonal cycles of different vegetation types. In addition to the vegetation distribution on land, they also show patterns of biological activity in the oceans. Our results indicate that improved sets of vegetation spectra might lead to more accurate and more specific identification of vegetation type in the future.

  7. Experimental and theoretical study of electronic structure of aluminum in extreme conditions with X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Festa, Floriane

    2013-01-01

    Matter in extreme conditions belongs to Warm Dense Matter regime which lays between dense plasma regime and condensed matter. This regime is still not well known, indeed it is very complex to generate such plasma in the laboratory to get experimental data and validate models. The goal of this thesis is to study electronic structure of aluminum in extreme conditions with X-ray absorption spectroscopy. Experimentally aluminum has reached high densities and high temperatures, up to now unexplored. An X-ray source has also been generated to probe highly compressed aluminum. Two spectrometers have recorded aluminum absorption spectra and aluminum density and temperature conditions have been deduced thanks to optical diagnostics. Experimental spectra have been compared to ab initio spectra, calculated in the same conditions. The theoretical goal was to validate the calculation method in high densities and high temperatures regime with the study of K-edge absorption modifications. We also used absorption spectra to study the metal-non metal transition which takes place at low density (density ≤ solid density). This transition could be study with electronic structure modifications of the system. (author) [fr

  8. Increasing detectivity of polarization modulation infrared reflection-absorption spectroscopy for the study of ultrathin films deposited on various substrates.

    Science.gov (United States)

    Saccani, J; Buffeteau, T; Desbat, B; Blaudez, D

    2003-10-01

    In this paper, we present a simple way to increase the sensitivity of polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS) for the study of ultrathin films deposited on dielectric and semiconductor substrates. The enhancement of the absorption band intensity is obtained by reducing the signal arising from the substrate. This is achieved by adding a polarizer after the sample in order to balance the polarized reflectivities of the sample. As a consequence, the contribution of the film to the PM-IRRAS signal is increased relative to that of the substrate. An enhancement factor of about 10 has been obtained for ultrathin organic films deposited on glass and spread at the air-water interface. This method has also allowed the study of the very thin native oxide layer present on silicon without the need for the reference spectrum of bare silicon.

  9. Investigation of neutral and ion dynamics in a HiPIMS plasma by tunable laser diode absorption spectroscopy (TDLAS)

    Science.gov (United States)

    Preissing, Patrick; Hecimovic, Ante; von Keudell, Achim

    2016-09-01

    High power impulse magnetron sputtering (HiPIMS) discharges are known for complex plasma interactions, and complex temporal and spatial dynamics. Spatial and temporal dynamic of argon metastable (Arm), Ti atom (Ti0) and Ti ion (Ti+) density and temperature is studied by an extended tunable diode laser absorption spectroscopy setup (TDLAS) during a HiPIMS pulse. The TDLAS setup used a beam expander in combination with a 6 photo diode array to simultaneously measure spatial (resolution 5 mm) and time resolved absorption profiles of an Arm, Ti0 and Ti+ transition. This in combination with moving the magnetron in axial direction gives a complete 2D map of the density evolution. Temporal resolution of 400 ns was achieved by recording the photo diode signal on the National Instruments card. Final results allowed to investigate temporal evolution of the observed species in the volume between the target and the substrate.

  10. Measurements of size and composition of particles in polar stratospheric clouds from infrared solar absorption spectra

    International Nuclear Information System (INIS)

    Kinne, S.; Toon, O.B.; Toon, G.C.; Farmer, C.B.; Browell, E.V.; McCormick, M.P.

    1989-01-01

    The attenuation of solar radiation between 1.8- and 15-μm wavelength was measured with the airborne Jet Propulsion Laboratory Mark IV interferometer during the Airborne Antarctic Ozone Expedition in 1987. The measurements not only provide information about the abundance of stratospheric gases, but also about the optical depths of polar stratospheric clouds (PSCs) at wavelengths of negligible gas absorption. The spectral dependence of the PSC optical depth contains information about PSC particle size and particle composition. Thirty-three PSC cases were analyzed and categorized into two types. Type I clouds contain particles with radii of about 0.5 μm and nitric acid concentrations greater than 40%. Type II clouds contain particles composed of water ice with radii of 6 μm and larger. Cloud altitudes were determined from 1.064-μm backscattering observations of the airborne Langley DIAL lidar system. Based on the PSC geometrical thickness, both mass and particle density were estimated. Type I clouds typically had visible wavelength optical depths of about 0.008, mass densities of about 20 ppb, and about 2 particles/cm 3 . The observed type II clouds had optical depths of about 0.03, mass densities of about 400 ppb mass, and about 0.03 particles/cm 3 . The detected PSC type I clouds extended to altitudes of 21 km and were nearly in the ozone-depleted region of the polar stratosphere. The observed type II cases during September were predominantly found at altitudes below 15 km

  11. Flexible, Lightweight Quantum Dot Solar Cells Using Plasmonic-Enhanced Light Absorption

    Data.gov (United States)

    National Aeronautics and Space Administration — Solar cells, or photovoltaic cells, are critical to NASA operations due to the abundance and availability of solar power. Current photovoltaic technology is based on...

  12. On-line monitoring of odorant in natural gas mixtures of different composition by the infrared absorption spectroscopy method

    Science.gov (United States)

    Kireev, S. V.; Shnyrev, S. L.

    2018-03-01

    This paper reports on the results of research aimed at solving the problem of on-line monitoring of odorant in natural gas mixtures in order to make the odorization process effective and ensure the safety of main gas pipeline exploitation. Our results show that using the infrared absorption spectroscopy method is promising for this purpose. Using radiation sources operating in the spectral range 6–15 µm allows us to obtain an odorant detection sensitivity of approximately 5 ppm in gas mixtures of different composition.

  13. Quantitative depth profiling of photoacid generators in photoresist materials by near-edge X-ray absorption fine structure spectroscopy

    International Nuclear Information System (INIS)

    Prabhu, Vivek M.; Sambasivan, Sharadha; Fischer, Daniel; Sundberg, Linda K.; Allen, Robert D.

    2006-01-01

    Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy was used to quantify the surface composition and depth profiling of photoacid generators in thin film photoresist materials by varying the entrance-grid bias of a partial electron yield detector. By considering model compositional profiles, NEXAFS distinguishes the surface molar excess within the top 6 nm from the bulk. A surface enriched system, triphenylsulfonium perfluorooctanesulfonate, is contrasted with a perfluorobutanesulfonate photoacid generator, which displays an appreciable surface profile within a 6 nm segregation length scale. These results, while applied to 193-nm photoresist materials, highlight a general approach to quantify NEXAFS partial electron yield data

  14. Effect of Pressure on Magnetoelastic Coupling in 3d Metal Alloys Studied with X-Ray Absorption Spectroscopy

    Science.gov (United States)

    Pascarelli, S.; Ruffoni, M. P.; Trapananti, A.; Mathon, O.; Aquilanti, G.; Ostanin, S.; Staunton, J. B.; Pettifer, R. F.

    2007-12-01

    Using x-ray absorption spectroscopy, we have studied the effect of pressure on femtometer-scale bond strain due to anisotropic magnetostriction in a thin FeCo film. At 7 GPa local magnetostrictive strain is found to be larger than at ambient, in agreement with spin-polarized ab initio electronic structure calculations, but contrary to the expected effect of compression on bond stiffness. The availability of high pressure data on local magnetostrictive strain opens new capabilities for validating theoretical predictions and can lead to the development of materials with the desired properties.

  15. Broadband cavity-enhanced absorption spectroscopy in the ultraviolet spectral region for measurements of nitrogen dioxide and formaldehyde

    Science.gov (United States)

    Washenfelder, R. A.; Attwood, A. R.; Flores, J. M.; Zarzana, K. J.; Rudich, Y.; Brown, S. S.

    2016-01-01

    Formaldehyde (CH2O) is the most abundant aldehyde in the atmosphere, and it strongly affects photochemistry through its photolysis. We describe simultaneous measurements of CH2O and nitrogen dioxide (NO2) using broadband cavity-enhanced absorption spectroscopy in the ultraviolet spectral region. The light source consists of a continuous-wave diode laser focused into a Xenon bulb to produce a plasma that emits high-intensity, broadband light. The plasma discharge is optically filtered and coupled into a 1 m optical cavity. The reflectivity of the cavity mirrors is 0.99930 ± 0.00003 (1- reflectivity = 700 ppm loss) at 338 nm, as determined from the known Rayleigh scattering of He and zero air. This mirror reflectivity corresponds to an effective path length of 1.43 km within the 1 m cell. We measure the cavity output over the 315-350 nm spectral region using a grating monochromator and charge-coupled device array detector. We use published reference spectra with spectral fitting software to simultaneously retrieve CH2O and NO2 concentrations. Independent measurements of NO2 standard additions by broadband cavity-enhanced absorption spectroscopy and cavity ring-down spectroscopy agree within 2 % (slope for linear fit = 1.02 ± 0.03 with r2 = 0.998). Standard additions of CH2O measured by broadband cavity-enhanced absorption spectroscopy and calculated based on flow dilution are also well correlated, with r2 = 0.9998. During constant mixed additions of NO2 and CH2O, the 30 s measurement precisions (1σ) of the current configuration were 140 and 210 pptv, respectively. The current 1 min detection limit for extinction measurements at 315-350 nm provides sufficient sensitivity for measurement of trace gases in laboratory experiments and ground-based field experiments. Additionally, the instrument provides highly accurate, spectroscopically based trace gas detection that may complement higher precision techniques based on non-absolute detection methods. In addition to

  16. Evaluation of emery dust on the manufacture of abrasives by neutron activation analysis and atomic absorption spectroscopy

    International Nuclear Information System (INIS)

    Granados Correa, F.

    1992-01-01

    In this work it is presented an evaluation on the degree of contamination by emery dust in a working area where abrasives are manufactured, in a factory located in the industrial area of Toluca City by neutron activation analysis and atomic absorption spectroscopy. The samples were collected on Whatman filters and attacked with hot concentrated HCl. The elements founded were: Al, Si, V, Mg, Br, Mn, Ni, Zn, Fe, Cr, Ca and Pb. They are a risk for the health of the workers. (Author)

  17. Study of the Photodegradation Process of Vitamin E Acetate by Optical Absorption, Fluorescence, and Thermal Lens Spectroscopy

    Science.gov (United States)

    Tiburcio-Moreno, J. A.; Marcelín-Jiménez, G.; Leanos-Castaneda, O. L.; Yanez-Limon, J. M.; Alvarado-Gil, J. J.

    2012-11-01

    The stability of vitamin E acetate exposed to ultraviolet (UV) light was studied using three spectroscopic methods. An ethanol solution of vitamin E acetate was treated with either UVC light (254 nm) or UVA light (366 nm) during a period of 10 min followed by a study of UV-Vis optical absorption, then by fluorescence spectroscopy excitation by UV radiation at either 290 nm or 368 nm and, finally the solution was studied by thermal lens spectroscopy. Immediately, the same solution of vitamin E acetate was subjected to the UV irradiation process until completion of six periods of irradiation and measurements. UVC light treatment induced the appearance of a broad absorption band in the range of 310 nm to 440 nm with maximum absorbance at 368 nm, which progressively grew as the time of the exposure to UVC light increases. In contrast, UVA light treatment did not affect the absorption spectra of vitamin E acetate. Fluorescence spectra of the vitamin E acetate (without UV light treatment) showed no fluorescence when excited with 368 nm while exciting with 290 nm, an intense and broad emission band (300 nm to 440 nm) with a maximum at 340 nm appeared. When vitamin E acetate was treated with UVC light, this emission band progressively decreased as the time of the UVC light irradiation grew. No signal from UV-untreated vitamin E acetate could be detected by the thermal lens method. Interestingly, as the time of the UVC light treatment increased, the thermal lens signal progressively grew. Additional experiments performed to monitor the time evolution of the process during continuous UVC treatment of the vitamin E acetate using thermal lens spectroscopy exhibited a progressive increase of the thermal lens signal reaching a plateau at about 8000 s. This study shows that the vitamin E acetate is stable when it is irradiated with UVA light, while the irradiation with UVC light induces the formation of photodegradation products. Interestingly, this photodegradation process using

  18. Carbon dioxide adsorption on a ZnO(101[combining macron]0) substrate studied by infrared reflection absorption spectroscopy.

    Science.gov (United States)

    Buchholz, Maria; Weidler, Peter G; Bebensee, Fabian; Nefedov, Alexei; Wöll, Christof

    2014-01-28

    The adsorption of carbon dioxide on the mixed-terminated ZnO(101[combining macron]0) surface of a bulk single crystal was studied by UHV Infrared Reflection Absorption Spectroscopy (IRRAS). In contrast to metals, the classic surface selection rule for IRRAS does not apply to bulk oxide crystals, and hence vibrational bands can also be observed for s-polarized light. Although this fact substantially complicates data interpretation, a careful analysis allows for a direct determination of the adsorbate geometry. Here, we demonstrate the huge potential of IR-spectroscopy for investigations on oxide single crystal surfaces by considering all three components of the incident polarized light separately. We find that the tridentate (surface) carbonate is aligned along the [0001] direction. A comparison to data reported previously for CO2 adsorbed on the surfaces of ZnO nanoparticles provides important insight into the role of defects in the surface chemistry of powder particles.

  19. CO adsorption on Pd(100) studied by multimodal ambient pressure X-ray photoelectron and infrared reflection absorption spectroscopies

    Science.gov (United States)

    Head, Ashley R.; Karslıoǧlu, Osman; Gerber, Timm; Yu, Yi; Trotochaud, Lena; Raso, Joseph; Kerger, Philipp; Bluhm, Hendrik

    2017-11-01

    The adsorption of CO on Pd(100) was investigated using simultaneous ambient pressure X-ray photoelectron spectroscopy (APXPS) and infrared reflection absorption infrared spectroscopy (IRRAS). The measurements were performed as a function of CO partial pressures from ultra-high vacuum to 0.5 Torr. Total CO coverages estimated from the complementary APXPS and IRRAS measurements are in good agreement. A signal for atop CO, which is uncommon for Pd(100), was observed in the IRRAS data and was used to identify the C 1 s binding energy of this species. Discerning this binding configuration of CO on the Pd(100) surface at elevated pressures has significance for catalytic reactions involving CO, where bridging CO is often the only configuration considered. We also detail the combined APXPS/IRRAS instrumentation and discuss ways to improve these multimodal measurements, which should have wide applicability across many areas of surface and interface science.

  20. First-principles simulation of transient x-ray absorption spectroscopy of photo-excited molecular systems

    Science.gov (United States)

    Pemmaraju, Das; Closser, Kristina; Prendergast, David; Simes; Molecular Foundry Collaboration Collaboration

    We explore the utility of beyond-ground-state density functional methods such as constrained density functional theory (c-DFT) and time-dependent density functional theory (TDDFT) in the interpretation of time-resolved X-ray absorption spectroscopies investigating chemical dynamics in photo-excited molecular systems. Recent results based on a methodology that combines a state-by-state self-consistent field description such as c-DFT with a frequency domain linear-response TDDFT approach to model the core-level spectroscopy of photo-excited ring-opening dynamics in small molecular systems is discussed. Illustrative case studies involving the strong-field ionization of Selenophene and resonant UV-vis excitation of 1,3-cyclohexadiene are presented.

  1. Solar Cells from Earth-Abundant Semiconductors with Plasmon-Enhanced Light Absorption

    Energy Technology Data Exchange (ETDEWEB)

    Atwater, Harry

    2012-04-30

    Progress is reported in these areas: Plasmonic Light Trapping in Thin Film a-Si Solar Cells; Plasmonic Light Trapping in Thin InGaN Quantum Well Solar Cells; and Earth Abundant Cu{sub 2}O and Zn{sub 3}P{sub 2} Solar Cells.

  2. The speciation of soluble sulphur compounds in bacterial culture fluids by X-ray absorption near edge structure spectroscopy.

    Science.gov (United States)

    Franz, Bettina; Lichtenberg, Henning; Hormes, Josef; Dahl, Christiane; Prange, Alexander

    2009-11-01

    Over the last decade X-ray absorption near edge structure (XANES) spectroscopy has been used in an increasing number of microbiological studies. In addition to other applications it has served as a valuable tool for the investigation of the sulphur globules deposited intra- or extracellularly by certain photo- and chemotrophic sulphur-oxidizing (Sox) bacteria. For XANES measurements, these deposits can easily be concentrated by filtration or sedimentation through centrifugation. However, during oxidative metabolism of reduced sulphur compounds, such as sulphide or thiosulphate, sulphur deposits are not the only intermediates formed. Soluble intermediates such as sulphite may also be produced and released into the medium. In this study, we explored the potential of XANES spectroscopy for the detection and speciation of sulphur compounds in culture supernatants of the phototrophic purple sulphur bacterium Allochromatium vinosum. More specifically, we investigated A. vinosum DeltasoxY, a strain with an in frame deletion of the soxY gene. This gene encodes an essential component of the thiosulphate-oxidizing Sox enzyme complex. Improved sample preparation techniques developed for the DeltasoxY strain allowed for the first time not only the qualitative but also the quantitative analysis of bacterial culture supernatants by XANES spectroscopy. The results thus obtained verified and supplemented conventional HPLC analysis of soluble sulphur compounds. Sulphite and also oxidized organic sulphur compounds were shown by XANES spectroscopy to be present, some of which were not seen when standard HPLC protocols were used.

  3. Femtosecond X-ray absorption and emission spectroscopy on zno nanoparticles in solution

    DEFF Research Database (Denmark)

    Penfold, Thomas J.; Szlachetko, Jakub; Gawelda, Wojciech

    2016-01-01

    We have performed femtosecond X-ray spectroscopy measurements after UV photoexcitation of a colloidal solution of ZnO nanoparticles. The results indicate sub-ps hole trapping at oxygen vacancies with shallowly-trapped electrons in the conduction band.......We have performed femtosecond X-ray spectroscopy measurements after UV photoexcitation of a colloidal solution of ZnO nanoparticles. The results indicate sub-ps hole trapping at oxygen vacancies with shallowly-trapped electrons in the conduction band....

  4. Water vapor spectroscopy in the 815-nm wavelength region for Differential Absorption Lidar measurements

    Science.gov (United States)

    Ponsardin, Patrick; Browell, Edward V.

    1995-01-01

    The differential absorption lidar (DIAL) technique was first applied to the remote measurement of atmospheric water vapor profiles from airborne platforms in 1981. The successful interpretation of the lidar profiles relies strongly on an accurate knowledge of specific water vapor absorption line parameters: line strength, pressure broadening coefficient, pressure-induced shift coefficient and the respective temperature-dependence factors. NASA Langley Research Center has developed and is currently testing an autonomous airborne water vapor lidar system: LASE (Lidar Atmospheric Sensing Experiment). This DIAL system uses a Nd:YAG-pumped Ti:Sapphire laser seeded by a diode laser as a lidar transmitter. The tunable diode has been selected to operate in the 813-818 nm wavelength region. This 5-nm spectral interval offers a large distribution of strengths for temperature-insensitive water vapor absorption lines. In support of the LASE project, a series of spectroscopic measurements were conducted for the 16 absorption lines that have been identified for use in the LASE measurements. Prior to this work, the experimental data for this water vapor absorption band were limited - to our knowledge - to the line strengths and to the line positions.

  5. In situ X-ray absorption spectroscopy of transition metal based water oxidation catalysts.

    Science.gov (United States)

    van Oversteeg, Christina H M; Doan, Hoang Q; de Groot, Frank M F; Cuk, Tanja

    2017-01-03

    X-ray absorption studies of the geometric and electronic structure of primarily heterogeneous Co, Ni, and Mn based water oxidation catalysts are reviewed. The X-ray absorption near edge and extended X-ray absorption fine structure studies of the metal K-edge, characterize the metal oxidation state, metal-oxygen bond distance, metal-metal distance, and degree of disorder of the catalysts. These properties guide the coordination environment of the transition metal oxide radical that localizes surface holes and is required to oxidize water. The catalysts are investigated both as-prepared, in their native state, and under reaction conditions, while transition metal oxide radicals are generated. The findings of many experiments are summarized in tables. The advantages of future X-ray experiments on water oxidation catalysts, which include the limited data available of the oxygen K-edge, metal L-edge, and resonant inelastic X-ray scattering, are discussed.

  6. Excited-State Dynamics of Carotenoids Studied by Femtosecond Transient Absorption Spectroscopy

    International Nuclear Information System (INIS)

    Lee, Ingu; Pang, Yoonsoo; Lee, Sebok

    2014-01-01

    Carotenoids, natural antenna pigments in photosynthesis share a symmetric backbone of conjugated polyenes. Contrary to the symmetric and almost planar geometries of carotenoids, excited state structure and dynamics of carotenoids are exceedingly complex. In this paper, recent infrared and visible transient absorption measurements and excitation dependent dynamics of 8'-apo-β-caroten-8'-al and 7',7'-dicyano-7'-apo-β-carotene will be reviewed. The recent visible transient absorption measurements of 8'-apo-β-caroten-8'-al in polar and nonpolar solvents will also be introduced to emphasize the complex excited-state dynamics and unsolved problems in the S 2 and S 1 excited states

  7. Size-selective extended X-ray absorption fine structure spectroscopy of free selenium clusters

    International Nuclear Information System (INIS)

    Nagaya, K.; Yao, M.; Hayakawa, T.; Ohmasa, Y.; Kajihara, Y.; Ishii, M.; Katayama, Y.

    2002-01-01

    In a recent paper [M. Yao et al., J. Synchrotron Radiat. 8, 542 (2001)], we proposed a new method for the size-selective EXAFS (extended x-ray absorption fine structure) of neutral-free clusters, in which not only the x-ray absorption process but also the deexcitation processes are utilized as the structural information. In order to verify this method experimentally, we have developed the synchronous measurements of EXAFS and photoelectron photoion coincidence and carried them out for a Se cluster beam by utilizing the third-generation intense x-ray source. The EXAFS spectra for Se small clusters have been obtained and compared critically with theoretical predictions

  8. Experimental diagnosis of the influence of operational variables on the performance of a solar absorption cooling system

    International Nuclear Information System (INIS)

    Venegas, M.; Rodriguez-Hidalgo, M.C.; Salgado, R.; Lecuona, A.; Rodriguez, P.; Gutierrez, G.

    2011-01-01

    This paper presents the analysis of the performance of a solar cooling facility along one summer season using a commercial single-effect water-lithium bromide absorption chiller aiming at domestic applications. The facility works only with solar energy using flat plate collectors and it is located at Universidad Carlos III de Madrid, Spain. The statistical analysis performed with the gathered data shows the influence of five daily operational variables on the system performance. These variables are solar energy received along the day (H) and the average values, along the operating period of the solar cooling facility (from sunrise to the end of the cold-water production), of the ambient temperature (T -bar ), the wind velocity magnitude (V), the wind direction (θ) and the relative humidity (RH). First order correlation functions are given. The analysis of the data allows concluding that the most influential variables on the daily cooling energy produced and the daily averaged solar COP are H, V and θ. The period length of cold-water production is determined mainly by H and T -bar .

  9. Experimental diagnosis of the influence of operational variables on the performance of a solar absorption cooling system

    Energy Technology Data Exchange (ETDEWEB)

    Venegas, M.; Rodriguez-Hidalgo, M.C.; Lecuona, A.; Rodriguez, P.; Gutierrez, G. [Dpto. Ingenieria Termica y de Fluidos, Universidad Carlos III de Madrid, Avda. Universidad 30, 28911 Leganes, Madrid (Spain); Salgado, R. [Dpto. Ingenieria Mecanica, Universidad Interamericana de Puerto Rico, Recinto de Bayamon, 500 Carretera Dr. John Will Harris Bayamon, PR 00957-6257 (United States)

    2011-04-15

    This paper presents the analysis of the performance of a solar cooling facility along one summer season using a commercial single-effect water-lithium bromide absorption chiller aiming at domestic applications. The facility works only with solar energy using flat plate collectors and it is located at Universidad Carlos III de Madrid, Spain. The statistical analysis performed with the gathered data shows the influence of five daily operational variables on the system performance. These variables are solar energy received along the day (H) and the average values, along the operating period of the solar cooling facility (from sunrise to the end of the cold-water production), of the ambient temperature (anti T), the wind velocity magnitude (V), the wind direction ({theta}) and the relative humidity (RH). First order correlation functions are given. The analysis of the data allows concluding that the most influential variables on the daily cooling energy produced and the daily averaged solar COP are H, V and {theta}. The period length of cold-water production is determined mainly by H and anti T. (author)

  10. Snapshot imaging spectroscopy of the solar transition region: The Multi-Order Solar EUV Spectrograph (MOSES) sounding rocket mission

    Science.gov (United States)

    Fox, James Lewis

    We have developed a revolutionary spectroscopic technique for solar research in the extreme ultraviolet. This slitless spectrographic technique allows snapshot imaging spectroscopy with data exactly cotemporal and cospectral. I have contributed to the successful realization of an application of this technique in the Multi-Order Solar EUV Spectrograph, MOSES . This instrument launched 2006 Feb 8 as a NASA sounding rocket payload and successfully returned remarkable data of the solar transition region in the He II 304Å spectral line. The unique design of this spectrometer allows the study of transient phenomena in the solar atmosphere, with spatial, spectral, and temporal resolution heretofore unachievable in concert, over a wide field of view. The fundamental concepts behind the MOSES spectrometer are broadly applicable to many solar spectral lines and phenomena and the instrument thus represents a new instrumentation technology. The early fruits of this labor are here reported: the first scientific discovery with the MOSES sounding rocket instrument, our observation of a transition region explosive event, phenomena observed with slit spectrographs since at least 1975, most commonly in lines of C IV (1548Å 1550Å) and Si IV (1393Å, 1402Å). This explosive event is the first seen in He II 304Å. With our novel slitless imaging spectrograph, we are able to see the spatial structure of the event. We observe a bright core expelling two jets that are distinctly non-collinear, in directions that are not anti-parallel, in contradiction to standard models of explosive events, which give collinear jets. The jets have sky-plane velocities of order 75 km s -1 and line-of-sight velocities of +75 km s-1 (blue) and -30 km s-1 (red). The core is a region of high non-thermal doppler broadening, characteristic of explosive events, with maximal broadening 380 km s-1 FWHM. It is possible to resolve the core broadening into red and blue line-of-sight components of maximum doppler

  11. NO THERMAL INVERSION AND A SOLAR WATER ABUNDANCE FOR THE HOT JUPITER HD 209458B FROM HST /WFC3 SPECTROSCOPY

    Energy Technology Data Exchange (ETDEWEB)

    Line, Michael R. [NASA Ames Research Center, Moffet Field, CA 94035 (United States); Stevenson, Kevin B.; Bean, Jacob; Kreidberg, Laura [Department of Astronomy and Astrophysics, University of Chicago, 5640 S Ellis Avenue, Chicago, IL 60637 (United States); Desert, Jean-Michel [University of Amsterdam (Netherlands); Fortney, Jonathan J. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 (United States); Madhusudhan, Nikku [Institute of Astronomy, University of Cambridge, Cambridge CB3 0HA (United Kingdom); Showman, Adam P. [Department of Planetary Sciences and Lunar and Planetary Laboratory, University of Arizona, 1629 E. University Blvd., Tucson, AZ 85721 (United States); Diamond-Lowe, Hannah [Department of Astronomy, Harvard Smithsonian Center for Astrophysics, 60 Garden Street, MS-10, Cambridge, MA 02138 (United States)

    2016-12-01

    The nature of the thermal structure of hot Jupiter atmospheres is one of the key questions raised by the characterization of transiting exoplanets over the past decade. There have been claims that many hot Jupiters exhibit atmospheric thermal inversions. However, these claims have been based on broadband photometry rather than the unambiguous identification of emission features with spectroscopy, and the chemical species that could cause the thermal inversions by absorbing stellar irradiation at high altitudes have not been identified despite extensive theoretical and observational effort. Here we present high-precision Hubble Space Telescope WFC3 observations of the dayside thermal emission spectrum of the hot Jupiter HD 209458b, which was the first exoplanet suggested to have a thermal inversion. In contrast to previous results for this planet, our observations detect water in absorption at 6.2 σ confidence. When combined with Spitzer photometry, the data are indicative of a monotonically decreasing temperature with pressure over the range of 1–0.001 bars at 7.7 σ confidence. We test the robustness of our results by exploring a variety of model assumptions, including the temperature profile parameterization, presence of a cloud, and choice of Spitzer data reduction. We also introduce a new analysis method to determine the elemental abundances from the spectrally retrieved mixing ratios with thermochemical self-consistency and find plausible abundances consistent with solar metallicity (0.06–10 × solar) and carbon-to-oxygen ratios less than unity. This work suggests that high-precision spectrophotometric results are required to robustly infer thermal structures and compositions of extrasolar planet atmospheres and to perform comparative exoplanetology.

  12. The first X-ray imaging spectroscopy of quiescent solar active regions with NuSTAR

    DEFF Research Database (Denmark)

    Hannah, Iain G.; Grefenstette, Brian W.; Smith, David M.

    2016-01-01

    We present the first observations of quiescent active regions (ARs) using the Nuclear Spectroscopic Telescope Array (NuSTAR), a focusing hard X-ray telescope capable of studying faint solar emission from high-temperature and non-thermal sources. We analyze the first directly imaged and spectrally...... resolved X-rays above 2 keV from non-flaring ARs, observed near the west limb on 2014 November 1. The NuSTAR X-ray images match bright features seen in extreme ultraviolet and soft X-rays. The NuSTAR imaging spectroscopy is consistent with isothermal emission of temperatures 3.1-4.4 MK and emission......, at least an order of magnitude stricter than previous limits. With longer duration observations and a weakening solar cycle (resulting in an increased livetime), future NuSTAR observations will have sensitivity to a wider range of temperatures as well as possible non-thermal emission....

  13. Double resonant absorption measurement of acetylene symmetric vibrational states probed with cavity ring down spectroscopy

    NARCIS (Netherlands)

    Karhu, J.; Nauta, J.; Vainio, M.; Metsala, M.; Hoekstra, S.; Halonen, L.

    2016-01-01

    A novel mid-infrared/near-infrared double resonant absorption setup for studying infrared-inactive vibrational states is presented. A strong vibrational transition in the mid-infrared region is excited using an idler beam from a singly resonant continuous-wave optical parametric oscillator, to

  14. A laser heating facility for energy-dispersive X-ray absorption spectroscopy

    DEFF Research Database (Denmark)

    Kantor, Innokenty; Marini, C.; Mathon, O.

    2018-01-01

    A double-sided laser heating setup for diamond anvil cells installed on the ID24 beamline of the ESRF is presented here. The setup geometry is specially adopted for the needs of energy-dispersive X-ray absorption spectroscopic (XAS) studies of materials under extreme pressure and temperature...

  15. Kinetics of formation of NiO nanoparticles by X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Meneses, C.T. [Departamento de Fisica, Universidade Federal do Ceara, Campus do Pici, CP 6030, 60455-760 Fortaleza, CE (Brazil)], E-mail: cristiano@fisica.ufc.br; Flores, W.H. [Centro de Ciencias Exatas e Tecnologicas, Universidade Federal de Pelotas, Campus de Bage, 96412-420 Bage, RS (Brazil); Sasaki, J.M. [Departamento de Fisica, Universidade Federal do Ceara, Campus do Pici, CP 6030, 60455-760 Fortaleza, CE (Brazil)

    2007-05-15

    We report the in situ X-ray absorption investigations to study kinetic formation on NiO nanoparticles growth. The effects caused in the initial stage of particles growth by different heating rates are investigated. XAS results show that the particles disorder appears for high heating rates and growth process is faster for low heating rates.

  16. Grazing incidence reflectivity and total electron yield effects in soft x-ray absorption spectroscopy

    NARCIS (Netherlands)

    Alders, D; Hibma, T; Sawatzky, G.A; Cheung, K.C.; van Dorssen, G.E.; Roper, M.D.; Padmore, H.A.; van der Laan, G.; Vogel, J; Sacchi, M.

    1997-01-01

    We report on a study of grazing incidence absorption and reflection spectra of NiO in the region of the Ni 2p edge. The aim is to evaluate the distortion of the near edge spectrum by the critical angle behavior of individual components within the spectrum. This can be used to improve the separation

  17. Low-energy solar neutrino spectroscopy with Borexino. Towards the detection of the solar pep and CNO neutrino flux

    International Nuclear Information System (INIS)

    Maneschg, Werner

    2011-01-01

    Borexino is a large-volume organic liquid scintillator detector of unprecedented high radiopurity which has been designed for low-energy neutrino spectroscopy in real time. Besides the main objective of the experiment, the measurement of the solar 7 Be neutrino flux, Borexino also aims at detecting solar neutrinos from the pep fusion process and from the CNO cycle. The detectability of these neutrinos is strictly connected to a successful rejection of all relevant background components. The identification and reduction of these background signals is the central subject of this dissertation. In the first part, contaminants induced by cosmic-ray muons and muon showers were analyzed. The dominant background is the cosmogenic radioisotope 11 C. Its rate is ∝10 times higher than the expected combined pep and CNO neutrino rate in the preferred energy window of observation at [0.8,1.3] MeV. Since 11 C is mostly produced under the release of a free neutron, 11 C can be tagged with a threefold coincidence (TFC) consisting of the muon signal, the neutron capture and the subsequent 11 C decay. By optimizing the TFC method and other rejection techniques, a 11 C rejection efficiency of 80% was achieved. This led to a neutrino-to-background ratio of 1:1.7, whereby 61% of statistics is lost. The second part of the work concerns the study of the external background. Especially long-range 2.6 MeV gamma rays from 208 Tl decays in the outer detector parts can reach the scintillator in the innermost region of the detector. For the determination of the resultant spectral shape, a custom-made ∝5 MBq 228 Th source was produced and an external calibration was carried out for the first time. The obtained calibration data and the achieved 11 C rejection efficiency will allow for the direct detection of solar pep and possibly also CNO neutrinos with Borexino. (orig.)

  18. Capacitance spectroscopy on n-type GaNAs/GaAs embedded quantum structure solar cells

    Science.gov (United States)

    Venter, Danielle; Bollmann, Joachim; Elborg, Martin; Botha, J. R.; Venter, André

    2018-04-01

    In this study, both deep level transient spectroscopy (DLTS) and admittance spectroscopy (AS) have been used to study the properties of electrically active deep level centers present in GaNAs/GaAs quantum wells (QWs) embedded in p-i-n solar cells. The structures were grown by molecular beam epitaxy (MBE). In particular, the electrical properties of samples with Si (n-type) doping of the QWs were investigated. DLTS revealed four deep level centers in the material, whereas only three were detected by AS. NextNano++ simulation software was used to model the sample band-diagrams to provide reasoning for the origin of the signals produced by both techniques.

  19. An A-D-A'-D-A type small molecule acceptor with a broad absorption spectrum for organic solar cells.

    Science.gov (United States)

    Miao, Junhui; Meng, Bin; Liu, Jun; Wang, Lixiang

    2018-01-02

    Organic molecules with wide absorption spectra exhibit great sunlight harvesting capability and are critically important for solar cell applications. In this manuscript, we develop an A-D-A'-D-A type small molecule acceptor (IID-IC) using isoindigo (IID) as the electron-deficient core unit (A'), thiophene as the electron-rich bridging units (D) and 2-(3-oxo-2,3-dihydroinden-1-ylidene)malononitrile (IC) as the electron-deficient endcapping groups (A). IID-IC shows a wide absorption spectrum with the full width at half maximum (FWHM) of 190 nm, which is almost twice that of a typical A-D-A type molecule acceptor. The wide absorption spectrum of IID-IC is possibly due to the partially suppressed intramolecular charge transfer effect with the additional electron-deficient core unit. An organic solar cell (OSC) device based on IID-IC exhibits the power conversion efficiency of 2.82% with broad photoresponse from 320 nm to 780 nm.

  20. Photocurrent spectroscopy of perovskite layers and solar cells: a sensitive probe of material degradation

    Czech Academy of Sciences Publication Activity Database

    Holovský, Jakub; De Wolf, S.; Werner, J.; Remeš, Zdeněk; Müller, Martin; Neykova, Neda; Ledinský, Martin; Černá, L.; Hrzina, P.; Löper, P.; Niesen, B.; Ballif, C.

    2017-01-01

    Roč. 8, č. 4 (2017), s. 838-843 ISSN 1948-7185 R&D Projects: GA ČR GJ17-26041Y; GA MŠk LM2015087 Grant - others:AV ČR(CZ) KONNECT-007 Program:Bilaterální spolupráce Institutional support: RVO:68378271 Keywords : photocurrent spectroscopy * perovskite layers * solar cells Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 9.353, year: 2016