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Sample records for absorption 2pa cross

  1. Ultraviolet absorption cross sections of hydrogen peroxide

    NASA Technical Reports Server (NTRS)

    Lin, C. L.; Rohatgi, N. K.; Demore, W. B.

    1978-01-01

    Absorption cross-sections of hydrogen peroxide vapor and of neutral aqueous solutions of hydrogen peroxide were measured in the wavelength range from 195 to 350 nm at 296 K. The spectrophotometric procedure is described, and the reported cross-sections are compared with values obtained by other researchers. Photodissociation coefficients of atmospheric H2O2 were calculated for direct absorption of unscattered solar radiation, and the vertical distributions of these coefficients are shown for various solar zenith angles.

  2. Universal Parameterization of Absorption Cross Sections

    NASA Technical Reports Server (NTRS)

    Tripathi, R. K.; Cucinotta, Francis A.; Wilson, John W.

    1999-01-01

    Our prior nuclear absorption cross sections model is extended for light systems (A less than or equal to 4) where either both projectile and target are light particles or one is a light particle and the other is a medium or heavy nucleus. The agreement with experiment is excellent for these cases as well. Present work in combination with our original model provides a comprehensive picture of absorption cross sections for light, medium, and heavy systems, a very valuable input for radiation protection studies.

  3. New Parameterization of Neutron Absorption Cross Sections

    NASA Astrophysics Data System (ADS)

    Tripathi, Ram K.; Wilson, John W.; Cucinotta, Francis A.

    1997-06-01

    Recent parameterization of absorption cross sections for any system of charged ion collisions, including proton-nucleus collisions, is extended for neutron-nucleus collisions valid from approx. 1 MeV to a few GeV, thus providing a comprehensive picture of absorption cross sections for any system of collision pairs (charged or uncharged). The parameters are associated with the physics of the problem. At lower energies, optical potential at the surface is important, and the Pauli operator plays an increasingly important role at intermediate energies. The agreement between the calculated and experimental data is better than earlier published results.

  4. New Parameterization of Neutron Absorption Cross Sections

    NASA Technical Reports Server (NTRS)

    Tripathi, Ram K.; Wilson, John W.; Cucinotta, Francis A.

    1997-01-01

    Recent parameterization of absorption cross sections for any system of charged ion collisions, including proton-nucleus collisions, is extended for neutron-nucleus collisions valid from approx. 1 MeV to a few GeV, thus providing a comprehensive picture of absorption cross sections for any system of collision pairs (charged or uncharged). The parameters are associated with the physics of the problem. At lower energies, optical potential at the surface is important, and the Pauli operator plays an increasingly important role at intermediate energies. The agreement between the calculated and experimental data is better than earlier published results.

  5. Rotational averaging of multiphoton absorption cross sections

    NASA Astrophysics Data System (ADS)

    Friese, Daniel H.; Beerepoot, Maarten T. P.; Ruud, Kenneth

    2014-11-01

    Rotational averaging of tensors is a crucial step in the calculation of molecular properties in isotropic media. We present a scheme for the rotational averaging of multiphoton absorption cross sections. We extend existing literature on rotational averaging to even-rank tensors of arbitrary order and derive equations that require only the number of photons as input. In particular, we derive the first explicit expressions for the rotational average of five-, six-, and seven-photon absorption cross sections. This work is one of the required steps in making the calculation of these higher-order absorption properties possible. The results can be applied to any even-rank tensor provided linearly polarized light is used.

  6. Rotational averaging of multiphoton absorption cross sections.

    PubMed

    Friese, Daniel H; Beerepoot, Maarten T P; Ruud, Kenneth

    2014-11-28

    Rotational averaging of tensors is a crucial step in the calculation of molecular properties in isotropic media. We present a scheme for the rotational averaging of multiphoton absorption cross sections. We extend existing literature on rotational averaging to even-rank tensors of arbitrary order and derive equations that require only the number of photons as input. In particular, we derive the first explicit expressions for the rotational average of five-, six-, and seven-photon absorption cross sections. This work is one of the required steps in making the calculation of these higher-order absorption properties possible. The results can be applied to any even-rank tensor provided linearly polarized light is used.

  7. Infrared absorption cross sections of alternative CFCs

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  8. Two-photon absorption cross section determination for fluorene derivatives: analysis of the methodology and elucidation of the origin of the absorption processes.

    PubMed

    Belfield, Kevin D; Bondar, Mykhailo V; Hernandez, Florencio E; Przhonska, Olga V; Yao, Sheng

    2007-11-08

    A comprehensive analysis of the well-known open aperture Z-scan method, using a modified equation for the change in transmittance, is presented and accounts for discrepancies in two-photon absorption (2PA) cross sections between picosecond and femtosecond excitation. This new approach takes into account excited-state absorption and stimulated emission of the molecules studied. The two-photon absorption cross-section spectra of a series of six fluorene-based derivatives, determined using picosecond pulses, over a broad spectral range (500-900 nm), and this approach using a modified fitting procedure in the open aperture Z-scan is reported. We demonstrate that the fluorene derivatives exhibit two-photon absorption cross-section values between 700 and 5000 GM, when excited into the two-photon allowed electronic state. Excitation anisotropy spectra, measured to investigate the nature of the observed linear and nonlinear absorption bands, are presented and provide insight into the 2PA process.

  9. Neutron absorption cross section of uranium-236

    SciTech Connect

    Macklin, R.L.; Alexander, C.W.

    1988-11-01

    U-236 neutron absorption was measured as a function of neutron time-of-flight from 20 eV to 1 MeV. The neutron flux was monitored with a /sup 6/Li glass scintillator. Average cross sections from 3 keV to 1 MeV were derived. Estimated uncertainties were less than 5% below 600 keV and increased to 9.5% at 1 MeV. Resonance parametrization from 20 eV to a few keV remains to be done. 17 refs., 5 figs., 3 tabs.

  10. Accurate universal parameterization of absorption cross sections II--neutron absorption cross sections

    NASA Technical Reports Server (NTRS)

    Tripathi, R. K.; Wilson, J. W.; Cucinotta, F. A.

    1997-01-01

    A recent parameterization (here after referred as paper I, Ref. [4]) of absorption cross sections for any system of charged ions collisions including proton -nucleus collisions, is extended for neutron-nucleus collisions valid from approximately 1 MeV to a few GeV, thus providing a comprehensive picture of absorption cross sections for any system of collision pair (charged and/or uncharged). The parameters are associated with the physics of the problem. At lower energies, the optical potential at the surface is important and the Pauli operator plays an increasingly important role at intermediate energies. The agreement between the calculated and experimental data is better than earlier published results.

  11. Accurate universal parameterization of absorption cross sections II — neutron absorption cross sections

    NASA Astrophysics Data System (ADS)

    Tripathi, R. K.; Wilson, John W.; Cucinotta, Francis A.

    1997-06-01

    A recent parameterization (here after referred as paper I, Ref. [4]) of absorption cross sections for any system of charged ions collisions including proton -nucleus collisions, is extended for neutron-nucleus collisions valid from ˜ 1 MeV to a few GeV, thus providing a comprehensive picture of absorption cross sections for any system of collision pair (charged and/or uncharged). The parameters are associated with the physics of the problem. At lower energies, the optical potential at the surface is important and the Pauli operator plays an increasingly important role at intermediate energies. The agreement between the calculated and experimental data is better than earlier published results.

  12. Universal Parameterization of Absorption Cross Sections

    NASA Technical Reports Server (NTRS)

    Tripathi, R. K.; Cucinotta, Francis A.; Wilson, John W.

    1997-01-01

    This paper presents a simple universal parameterization of total reaction cross sections for any system of colliding nuclei that is valid for the entire energy range from a few AMeV to a few AGeV. The universal picture presented here treats proton-nucleus collision as a special case of nucleus-nucleus collision, where the projectile has charge and mass number of one. The parameters are associated with the physics of the collision system. In general terms, Coulomb interaction modifies cross sections at lower energies, and the effects of Pauli blocking are important at higher energies. The agreement between the calculated and experimental data is better than all earlier published results.

  13. Temperature-dependent high resolution absorption cross sections of propane

    NASA Astrophysics Data System (ADS)

    Beale, Christopher A.; Hargreaves, Robert J.; Bernath, Peter F.

    2016-10-01

    High resolution (0.005 cm-1) absorption cross sections have been measured for pure propane (C3H8). These cross sections cover the 2550-3500 cm-1 region at five temperatures (from 296 to 700 K) and were measured using a Fourier transform spectrometer and a quartz cell heated by a tube furnace. Calibrations were made by comparison to the integrated cross sections of propane from the Pacific Northwest National Laboratory. These are the first high resolution absorption cross sections of propane for the 3 μm region at elevated temperatures. The cross sections provided may be used to monitor propane in combustion environments and in astronomical sources such as the auroral regions of Jupiter, brown dwarfs and exoplanets.

  14. Temperature-dependent absorption cross sections for hydrogen peroxide vapor

    NASA Technical Reports Server (NTRS)

    Nicovich, J. M.; Wine, P. H.

    1988-01-01

    Relative absorption cross sections for hydrogen peroxide vapor were measured over the temperature ranges 285-381 K for lambda = 230 nm-295 nm and 300-381 K for lambda = 193 nm-350 nm. The well established 298 K cross sections at 202.6 and 228.8 nm were used as an absolute calibration. A significant temperature dependence was observed at the important tropospheric photolysis wavelengths lambda over 300 nm. Measured cross sections were extrapolated to lower temperatures, using a simple model which attributes the observed temperature dependence to enhanced absorption by molecules possessing one quantum of O-O stretch vibrational excitation. Upper tropospheric photodissociation rates calculated using the extrapolated cross sections are about 25 percent lower than those calculated using currently recommended 298 K cross sections.

  15. Temperature-dependent absorption cross sections for hydrogen peroxide vapor

    NASA Astrophysics Data System (ADS)

    Nicovich, J. M.; Wine, P. H.

    1988-03-01

    Relative absorption cross sections for hydrogen peroxide vapor were measured over the temperature ranges 285-381 K for lambda = 230 nm-295 nm and 300-381 K for lambda = 193 nm-350 nm. The well established 298 K cross sections at 202.6 and 228.8 nm were used as an absolute calibration. A significant temperature dependence was observed at the important tropospheric photolysis wavelengths lambda over 300 nm. Measured cross sections were extrapolated to lower temperatures, using a simple model which attributes the observed temperature dependence to enhanced absorption by molecules possessing one quantum of O-O stretch vibrational excitation. Upper tropospheric photodissociation rates calculated using the extrapolated cross sections are about 25 percent lower than those calculated using currently recommended 298 K cross sections.

  16. Accurate universal parameterization of absorption cross sections III - light systems

    NASA Astrophysics Data System (ADS)

    Tripathi, R. K.; Cucinotta, F. A.; Wilson, J. W.

    1999-09-01

    Our prior nuclear absorption cross sections model [R.K. Tripathi, F.A. Cucinotta, J.W. Wilson, Nucl. Instr. and Meth. B 117 (1996) 347; R.K. Tripathi, J.W. Wilson, F.A. Cucinotta, Nucl. Instr. and Meth. B 129 (1997) 11] is extended for light systems ( A ⩽ 4) where either both projectile and target are light particles or one is light particle and the other is medium or heavy nucleus. The agreement with experiment is excellent for these cases as well. Present work in combination with our original model provides a comprehensive picture of absorption cross sections for light, medium and heavy systems. As a result the extended model can reliably be used in all studies where there is a need for absorption cross sections.

  17. Absorption Cross-Sections of Sodium Diatomic Molecules

    NASA Technical Reports Server (NTRS)

    Fong, Zeng-Shevan

    1985-01-01

    The absorption cross sections of sodium dimers were studied using a heat pipe over operating in the non-heat-pipe mode. Three wavelength regions were observed. They are in the red, the green-blue, and the near ultraviolet regions. The absorption cross section depends on the wavelength of the incident light. Representative peak values for the v"=0 progression in the red and green-blue regions are 2.59 A sup 2 (average value) and 11.77 A sup 2 (T sub ave=624 K). The value for the C greater than X transitions is several tenths A sup 2. The cross sections were measured from absorption spectra taken as a function of temperature.

  18. Ozone absorption cross section measurements in the Wulf bands

    NASA Technical Reports Server (NTRS)

    Anderson, Stuart M.; Hupalo, Peter; Mauersberger, Konrad

    1993-01-01

    A tandem dual-beam spectrometer has been developed to determine ozone absorption cross sections for 13 selected wavelengths between 750 and 975 nm at room temperature. The increasingly pronounced structure in this region may interfere with atmospheric trace gas transitions that are useful for remote sensing and complicate the measurement of aerosols. Ozone concentrations were determined by absorption at the common HeNe laser transition near 632.8 nm using the absolute cross section reported previously. The overall accuracy of these room temperature measurements is generally better than 2 percent. A synoptic near-IR spectrum scaled to these measurements is employed for comparison with results of previous studies.

  19. Tables of nuclear cross sections for galactic cosmic rays: Absorption cross sections

    NASA Technical Reports Server (NTRS)

    Townsend, L. W.; Wilson, J. W.

    1985-01-01

    A simple but comprehensive theory of nuclear reactions is presented. Extensive tables of nucleon, deuteron, and heavy-ion absorption cross sections over a broad range of energies are generated for use in cosmic ray shielding studies. Numerous comparisons of the calculated values with available experimental data show agreement to within 3 percent for energies above 80 MeV/nucleon and within approximately 10 percent for energies as low as 30 MeV/nucleon. These tables represent the culmination of the development of the absorption cross section formalism and supersede the preliminary absorption cross sections published previously in NASA TN D-8107, NASA TP-2138, and NASA TM-84636.

  20. Tables of nuclear cross sections for galactic cosmic rays: Absorption cross sections

    NASA Astrophysics Data System (ADS)

    Townsend, L. W.; Wilson, J. W.

    1985-05-01

    A simple but comprehensive theory of nuclear reactions is presented. Extensive tables of nucleon, deuteron, and heavy-ion absorption cross sections over a broad range of energies are generated for use in cosmic ray shielding studies. Numerous comparisons of the calculated values with available experimental data show agreement to within 3 percent for energies above 80 MeV/nucleon and within approximately 10 percent for energies as low as 30 MeV/nucleon. These tables represent the culmination of the development of the absorption cross section formalism and supersede the preliminary absorption cross sections published previously in NASA TN D-8107, NASA TP-2138, and NASA TM-84636.

  1. Absorption cross sections of the ClO dimer

    NASA Technical Reports Server (NTRS)

    Huder, K. J.; DeMore, W. B.

    1995-01-01

    The absorption cross sections of the ClO dimer, ClOOCl, are important to the photochemistry of ozone depletion in the Antarctic. In this work, new measurements were made of the dimer cross sections at 195 K. the results yield somewhat lower values in the long wavelength region, compared to those currently recommended in the NASA data evaluation (JPL 94-26). The corresponding solar photodissociation rates in the Antarctic are reduced by about 40%.

  2. Chirality dependence of the absorption cross section of carbon nanotubes.

    PubMed

    Vialla, Fabien; Roquelet, Cyrielle; Langlois, Benjamin; Delport, Géraud; Santos, Silvia Morim; Deleporte, Emmanuelle; Roussignol, Philippe; Delalande, Claude; Voisin, Christophe; Lauret, Jean-Sébastien

    2013-09-27

    The variation of the optical absorption of carbon nanotubes with their geometry has been a long-standing question at the heart of both metrological and applicative issues, in particular because optical spectroscopy is one of the primary tools for the assessment of the chiral species abundance of samples. Here, we tackle the chirality dependence of the optical absorption with an original method involving ultraefficient energy transfer in porphyrin-nanotube compounds that allows uniform photoexcitation of all chiral species. We measure the absolute absorption cross section of a wide range of semiconducting nanotubes at their S22 transition and show that it varies by up to a factor of 2.2 with the chiral angle, with type I nanotubes showing a larger absorption. In contrast, the luminescence quantum yield remains almost constant.

  3. Chirality Dependence of the Absorption Cross Section of Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Vialla, Fabien; Roquelet, Cyrielle; Langlois, Benjamin; Delport, Géraud; Santos, Silvia Morim; Deleporte, Emmanuelle; Roussignol, Philippe; Delalande, Claude; Voisin, Christophe; Lauret, Jean-Sébastien

    2013-09-01

    The variation of the optical absorption of carbon nanotubes with their geometry has been a long-standing question at the heart of both metrological and applicative issues, in particular because optical spectroscopy is one of the primary tools for the assessment of the chiral species abundance of samples. Here, we tackle the chirality dependence of the optical absorption with an original method involving ultraefficient energy transfer in porphyrin-nanotube compounds that allows uniform photoexcitation of all chiral species. We measure the absolute absorption cross section of a wide range of semiconducting nanotubes at their S22 transition and show that it varies by up to a factor of 2.2 with the chiral angle, with type I nanotubes showing a larger absorption. In contrast, the luminescence quantum yield remains almost constant.

  4. Hadronic absorption cross sections of B{sub c}

    SciTech Connect

    Lodhi, M. A. K.; Akram, Faisal; Irfan, Shaheen

    2011-09-15

    The cross sections of B{sub c} absorption by {pi} mesons are calculated using a hadronic Lagrangian based on the SU(5) flavor symmetry. Calculated cross sections are found to be in the ranges 2-7 mb and 0.2-2 mb for the processes B{sub c}{sup +}{pi}{yields}DB and B{sub c}{sup +}{pi}{yields}D*B*, respectively, when the monopole form factor is included. These results could be useful in calculating the production rate of B{sub c} mesons in relativistic heavy ion collisions.

  5. Updated ozone absorption cross section will reduce air quality compliance

    NASA Astrophysics Data System (ADS)

    Sofen, E. D.; Evans, M. J.; Lewis, A. C.

    2015-07-01

    Photometric ozone measurements rely upon an accurate value of the ozone absorption cross section at 253.65 nm. This has recently been reevaluated by Viallon et al. (2015) as 1.8 % smaller than the accepted value (Hearn, 1961) used for the preceding fifty years. Thus, ozone measurements that applied the older cross section systematically underestimate the amount of ozone in air. We correct the reported historical surface data from North America and Europe and find that this modest change in cross section has a significant impact on the number of locations that are out of compliance with air quality regulations if the air quality standards remain the same. We find 18, 23, and 20 % increases in the number of sites that are out of compliance with current US, Canadian, and European ozone air quality health standards for the year 2012. Should the new cross section value be applied, it would impact attainment of air quality standards and compliance with relevant clean air acts, unless the air quality target values themselves were also changed proportionately. We draw attention to how a small change in gas metrology has a global impact on attainment and compliance with legal air quality standards. We suggest that further laboratory work to evaluate the new cross section is needed and suggest three possible technical and policy responses should the new cross section be adopted.

  6. Updated ozone absorption cross section will reduce air quality compliance

    NASA Astrophysics Data System (ADS)

    Sofen, E. D.; Evans, M. J.; Lewis, A. C.

    2015-12-01

    Photometric ozone measurements rely upon an accurate value of the ozone absorption cross section at 253.65 nm. This has recently been re-evaluated by Viallon et al. (2015) as 1.8 % smaller than the accepted value (Hearn, 1961) used for the preceding 50 years. Thus, ozone measurements that applied the older cross section systematically underestimate the amount of ozone in air. We correct the reported historical surface data from North America and Europe and find that this modest change in cross section has a significant impact on the number of locations that are out of compliance with air quality regulations if the air quality standards remain the same. We find 18, 23, and 20 % increases in the number of sites that are out of compliance with current US, Canadian, and European ozone air quality health standards for the year 2012. Should the new cross-section value be applied, it would impact attainment of air quality standards and compliance with relevant clean air acts, unless the air quality target values themselves were also changed proportionately. We draw attention to how a small change in gas metrology has a global impact on attainment and compliance with legal air quality standards. We suggest that further laboratory work to evaluate the new cross section is needed and suggest three possible technical and policy responses should the new cross section be adopted.

  7. Two-photon absorption cross sections within equation-of-motion coupled-cluster formalism using resolution-of-the-identity and Cholesky decomposition representations: Theory, implementation, and benchmarks

    NASA Astrophysics Data System (ADS)

    Nanda, Kaushik D.; Krylov, Anna I.

    2015-02-01

    The equation-of-motion coupled-cluster (EOM-CC) methods provide a robust description of electronically excited states and their properties. Here, we present a formalism for two-photon absorption (2PA) cross sections for the equation-of-motion for excitation energies CC with single and double substitutions (EOM-CC for electronically excited states with single and double substitutions) wave functions. Rather than the response theory formulation, we employ the expectation-value approach which is commonly used within EOM-CC, configuration interaction, and algebraic diagrammatic construction frameworks. In addition to canonical implementation, we also exploit resolution-of-the-identity (RI) and Cholesky decomposition (CD) for the electron-repulsion integrals to reduce memory requirements and to increase parallel efficiency. The new methods are benchmarked against the CCSD and CC3 response theories for several small molecules. We found that the expectation-value 2PA cross sections are within 5% from the quadratic response CCSD values. The RI and CD approximations lead to small errors relative to the canonical implementation (less than 4%) while affording computational savings. RI/CD successfully address the well-known issue of large basis set requirements for 2PA cross sections calculations. The capabilities of the new code are illustrated by calculations of the 2PA cross sections for model chromophores of the photoactive yellow and green fluorescent proteins.

  8. Two-photon absorption cross sections within equation-of-motion coupled-cluster formalism using resolution-of-the-identity and Cholesky decomposition representations: Theory, implementation, and benchmarks.

    PubMed

    Nanda, Kaushik D; Krylov, Anna I

    2015-02-14

    The equation-of-motion coupled-cluster (EOM-CC) methods provide a robust description of electronically excited states and their properties. Here, we present a formalism for two-photon absorption (2PA) cross sections for the equation-of-motion for excitation energies CC with single and double substitutions (EOM-CC for electronically excited states with single and double substitutions) wave functions. Rather than the response theory formulation, we employ the expectation-value approach which is commonly used within EOM-CC, configuration interaction, and algebraic diagrammatic construction frameworks. In addition to canonical implementation, we also exploit resolution-of-the-identity (RI) and Cholesky decomposition (CD) for the electron-repulsion integrals to reduce memory requirements and to increase parallel efficiency. The new methods are benchmarked against the CCSD and CC3 response theories for several small molecules. We found that the expectation-value 2PA cross sections are within 5% from the quadratic response CCSD values. The RI and CD approximations lead to small errors relative to the canonical implementation (less than 4%) while affording computational savings. RI/CD successfully address the well-known issue of large basis set requirements for 2PA cross sections calculations. The capabilities of the new code are illustrated by calculations of the 2PA cross sections for model chromophores of the photoactive yellow and green fluorescent proteins.

  9. Two-photon absorption cross sections within equation-of-motion coupled-cluster formalism using resolution-of-the-identity and Cholesky decomposition representations: Theory, implementation, and benchmarks

    SciTech Connect

    Nanda, Kaushik D.; Krylov, Anna I.

    2015-02-14

    The equation-of-motion coupled-cluster (EOM-CC) methods provide a robust description of electronically excited states and their properties. Here, we present a formalism for two-photon absorption (2PA) cross sections for the equation-of-motion for excitation energies CC with single and double substitutions (EOM-CC for electronically excited states with single and double substitutions) wave functions. Rather than the response theory formulation, we employ the expectation-value approach which is commonly used within EOM-CC, configuration interaction, and algebraic diagrammatic construction frameworks. In addition to canonical implementation, we also exploit resolution-of-the-identity (RI) and Cholesky decomposition (CD) for the electron-repulsion integrals to reduce memory requirements and to increase parallel efficiency. The new methods are benchmarked against the CCSD and CC3 response theories for several small molecules. We found that the expectation-value 2PA cross sections are within 5% from the quadratic response CCSD values. The RI and CD approximations lead to small errors relative to the canonical implementation (less than 4%) while affording computational savings. RI/CD successfully address the well-known issue of large basis set requirements for 2PA cross sections calculations. The capabilities of the new code are illustrated by calculations of the 2PA cross sections for model chromophores of the photoactive yellow and green fluorescent proteins.

  10. Excited state absorption spectra and intersystem crossing kinetics in diazanaphthalenes

    NASA Astrophysics Data System (ADS)

    Scott, Gary W.; Talley, Larry D.; Anderson, Robert W.

    1980-05-01

    Picosecond time-resolved, excited state absorption spectra in the visible following excitation at 355 nm are discussed for room temperature solutions of four diazanaphthalenes (DN)—quinoxaline (1,4-DN), quinazoline (1,3-DN), cinnoline (1,2-DN), and phthalazine (2,3-DN). Kinetics of singlet state decay are obtained by monitoring the decay of Sn←S1 bands. The intersystem crossing rate constant (kisc) is found to vary as kisc(1,4-DN)≳kisc(1,3-DN)≳kisc(1,2-DN). The kisc in phthalazine could not be determined from the weak, visible Sn←S1 absorption. Assuming rapid singlet vibrational relaxation and only minor effects due to energy gap variations, these experimental results agree with statistical limit predictions for the relative nonradiative rate. Calculations of the spin-orbit coupling matrix element βel= , using INDO wave functions, give the ordering βel(1,4-DN)≳βel(2,3-DN)≳βel(1,3-DN) ≳βel(1,2-DN).

  11. A simple formula for estimation of the absorption cross section of biological suspensions

    SciTech Connect

    Paramonov, L.E.

    1994-10-01

    A simple formula for the absorption cross section of biological suspensions is suggested. The error introduced by the formula into the measurements of absorption cross sections of polydisperse spherical particles described by the power, quasi-Gaussian, and gamma distributions, as well as of randomly oriented spheroidal particles is estimated. A formula for the dependence of the absorption cross section on the dispersion composition of a medium is given. 16 refs., 5 tabs.

  12. Quantitative infrared absorption cross sections of isoprene for atmospheric measurements

    DOE PAGES

    Brauer, C. S.; Blake, T. A.; Guenther, A. B.; ...

    2014-11-19

    Isoprene (C5H8, 2-methyl-1,3-butadiene) is a volatile organic compound (VOC) and is one of the primary contributors to annual global VOC emissions. Isoprene is produced primarily by vegetation as well as anthropogenic sources, and its OH- and O3-initiated oxidations are a major source of atmospheric oxygenated organics. Few quantitative infrared studies have been reported for isoprene, limiting the ability to quantify isoprene emissions via remote or in situ infrared detection. We thus report absorption cross sections and integrated band intensities for isoprene in the 600–6500 cm-1 region. The pressure-broadened (1 atmosphere N2) spectra were recorded at 278, 298, and 323 Kmore » in a 19.94 cm path-length cell at 0.112 cm-1 resolution, using a Bruker IFS 66v/S Fourier transform infrared (FTIR) spectrometer. Composite spectra are derived from a minimum of seven isoprene sample pressures, each at one of three temperatures, and the number densities are normalized to 296 K and 1 atm.« less

  13. MIE SCATTERING AND ABSORPTION CROSS SECTIONS FOR ABSORBING PARTICLES,

    DTIC Science & Technology

    ELECTROMAGNETIC RADIATION , SCATTERING), (*ABSORPTION, ELECTROMAGNETIC RADIATION ), REFRACTIVE INDEX, LIGHT, PARTICLES, PARTICLE SIZE, RESONANCE, ATMOSPHERIC REFRACTION, PLANETARY ATMOSPHERES, INTERSTELLAR MATTER

  14. Scattered light and accuracy of the cross-section measurements of weak absorptions: Gas and liquid phase UV absorption cross sections of CH3CFCl2

    NASA Technical Reports Server (NTRS)

    Fahr, A.; Braun, W.; Kurylo, M. J.

    1993-01-01

    Ultraviolet absorption cross sections of CH3CFCl2(HCFC-141b) were determined in the gas phase (190-260 nm) and liquid phase (230-260 mm) at 298 K. The liquid phase absorption cross sections were then converted into accurate gas phase values using a previously described procedure. It has been demonstrated that scattered light from the shorter-wavelength region (as little as several parts per thousand) can seriously compromise the absorption cross-section measurement, particularly at longer wavelengths where cross sections are low, and can be a source of discrepancies in the cross sections of weakly absorbing halocarbons reported in the literature. A modeling procedure was developed to assess the effect of scattered light on the measured absorption cross section in our experiments, thereby permitting appropriate corrections to be made on the experimental values. Modeled and experimental results were found to be in good agreement. Experimental results from this study were compared with other available determinations and provide accurate input for calculating the atmospheric lifetime of HCFC-141b.

  15. The Role of Cross-Cultural Absorptive Capacity in the Effectiveness of In-Country Cross-Cultural Training

    ERIC Educational Resources Information Center

    Tarique, Ibraiz; Caligiuri, Paula

    2009-01-01

    Based on the theory of absorptive capacity, this study examines the following question. In the context of cross-cultural training, can the amount of previously accumulated cultural knowledge affect the ability of a trainee to absorb further learning about a new culture, thus enhancing total knowledge and presumably cross-cultural adjustment?…

  16. Phenylene vinylene platinum(II) acetylides with prodigious two-photon absorption.

    PubMed

    Dubinina, Galyna G; Price, Randi S; Abboud, Khalil A; Wicks, Geoffrey; Wnuk, Pawel; Stepanenko, Yuriy; Drobizhev, Mikhail; Rebane, Aleksander; Schanze, Kirk S

    2012-11-28

    The linear and nonlinear optical properties of a series of linear and cross-conjugated platinum(II) acetylide complexes that contain extended p-(phenylene vinylene) chromophores are reported. The complexes exhibit very high femtosecond two-photon absorption (2PA) cross section values (σ(2) up to 10,000 GM), as measured by nonlinear transmission (NLT) and two-photon excited fluorescence (2PEF) methods. The large 2PA cross sections span a broad range of wavelengths, 570-810 nm, and they overlap with the triplet excited state absorption. Spectral coincidence of high cross section 2PA and triplet absorption is a key feature giving rise to efficient dual-mode optical power limiting (OPL).

  17. Representation of absorption cross sections in information system W@DIS

    NASA Astrophysics Data System (ADS)

    Voronina, Yu.; Lavrentiev, N.; Privezentsev, A.; Fazliev, A.; Firsov, K.

    2014-11-01

    Our research into generation of a set of absorption cross sections of atmospheric molecules is reviewed briefly. Particular emphasis is placed on a description of a software toolkit for building information objects that characterize molecules and weakly bound molecular complexes, an application that provides the import and export of the absorption cross sections and representation of metadata and ontolology of information resources collected in a set.

  18. [Study on temperature dependence of ultraviolet absorption cross sections of nitric oxide at high temperatures].

    PubMed

    Zhou, Jie; Zhang, Shi-Liang; Chen, Xiao-Hu

    2007-07-01

    To study the temperature dependence of ultraviolet absorption characteristics of NO species in flue gas, the absorption cross sections of NO in the spectral region 200-230 nm at temperatures ranging from 285 to 410 K were measured using a grating monochromator with 0.2 nm resolution, a deuterium lamp and a specially-fabricated closed sample cell. The absorption spectrum of NO consists of discrete bands superimposed on a continuous base. Results indicated that discrete absorption bands were present with a fixed wavelength interval of roughly 10.5 nm. The peaks of discrete bands decreased first and started to increase later as the temperature rose from 285 to 410 K, with a maximum relative variation of 19.3%. Peak position and half width of the absorption peaks did not exhibit apparent change with the variation of temperature. Continuous absorption cross section increased monotonously with the temperature, and the variation gradient gradually decrease with wavelength red shift. The absorption cross section of NO should not be considered as constant when applied in online monitoring of NO concentration in flue gas. A compensation calculation of absorption cross section with respect to temperature effect is indispensable for the purpose of improving online measurement precision of NO concentration.

  19. Experimental determination of single CdSe nanowire absorption cross sections through photothermal imaging.

    PubMed

    Giblin, Jay; Syed, Muhammad; Banning, Michael T; Kuno, Masaru; Hartland, Greg

    2010-01-26

    Absorption cross sections ((sigma)abs) of single branched CdSe nanowires (NWs) have been measured by photothermal heterodyne imaging (PHI). Specifically, PHI signals from isolated gold nanoparticles (NPs) with known cross sections were compared to those of individual CdSe NWs excited at 532 nm. This allowed us to determine average NW absorption cross sections at 532 nm of (sigma)abs = (3.17 +/- 0.44) x 10(-11) cm2/microm (standard error reported). This agrees well with a theoretical value obtained using a classical electromagnetic analysis ((sigma)abs = 5.00 x 10(-11) cm2/microm) and also with prior ensemble estimates. Furthermore, NWs exhibit significant absorption polarization sensitivities consistent with prior NW excitation polarization anisotropy measurements. This has enabled additional estimates of the absorption cross section parallel ((sigma)abs) and perpendicular ((sigma)abs(perpendicular) to the NW growth axis, as well as the corresponding NW absorption anisotropy ((rho)abs). Resulting values of (sigma)abs = (5.6 +/- 1.1) x 10(-11) cm2/microm, (sigma)abs(perpendicular) = (1.26 +/- 0.21) x 10(-11) cm2/microm, and (rho)abs = 0.63+/- 0.04 (standard errors reported) are again in good agreement with theoretical predictions. These measurements all indicate sizable NW absorption cross sections and ultimately suggest the possibility of future direct single NW absorption studies.

  20. Derivation of water vapour absorption cross-sections in the red region

    NASA Technical Reports Server (NTRS)

    Lal, M.; Chakrabarty, D. K.

    1994-01-01

    Absorption spectrum in 436 to 448 nm wavelength region gives NO2 and O3 column densities. This spectrum can also give H2O column density. The spectrum in the range of 655 to 667 nm contains absorption due to NO3 and H2O. Combining the absorption spectra in the wavelength ranges of 436 to 448 and 655 to 667 nm, water vapor absorption cross-sections in this range comes out to be of the order of 2.0 x 10(exp -24) cm(exp -2).

  1. Thermal neutron absorption cross section and clay mineral content for Miocene Carpathian samples

    PubMed

    Woznicka

    2000-12-01

    A correlation between the thermal neutron absorption cross section and the clay volume for samples from the chosen geological region is discussed. A comparison of the calculated and measured absorption cross sections as a function of clay volume allows an estimate to be made on the presence of highly absorbing impurities in clays. From the example presented, it was deduced that 105 ppm of B or 25 ppm of Gd in the clay minerals in the samples tested would be sufficient to explain the difference between the experimental and calculated cross sections.

  2. Target correlation effects on neutron-nucleus total, absorption, and abrasion cross sections

    NASA Technical Reports Server (NTRS)

    Cucinotta, Francis A.; Townsend, Lawrence W.; Wilson, John W.

    1991-01-01

    Second order optical model solutions to the elastic scattering amplitude were used to evaluate total, absorption, and abrasion cross sections for neutron nucleus scattering. Improved agreement with experimental data for total and absorption cross sections is found when compared with first order (coherent approximation) solutions, especially below several hundred MeV. At higher energies, the first and second order solutions are similar. There are also large differences in abrasion cross section calculations; these differences indicate a crucial role for cluster knockout in the abrasion step.

  3. Nucleon-nucleus interaction data base: Total nuclear and absorption cross sections

    NASA Astrophysics Data System (ADS)

    Wilson, J. W.; Townsend, L. W.; Buck, W. W.; Chun, S. Y.; Hong, B. S.; Lamkin, S. L.

    1988-08-01

    Neutron total cross sections are represented for Li to Pu targets at energies above 0.1 MeV and less than 100 MeV using a modified nuclear Ramsauer formalism. The formalism is derived for energies above 100 MeV by fitting theoretical cross sections. Neutron absorption cross sections are represented by analytic expressions of similar form, but shape resonance phenomena of the Ramsauer effect is not present. Elastic differential cross sections are given as a renormalized impulse approximation. These cross section data bases are useful for nucleon transport applications.

  4. Nucleon-nucleus interaction data base: Total nuclear and absorption cross sections

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Townsend, L. W.; Buck, W. W.; Chun, S. Y.; Hong, B. S.; Lamkin, S. L.

    1988-01-01

    Neutron total cross sections are represented for Li to Pu targets at energies above 0.1 MeV and less than 100 MeV using a modified nuclear Ramsauer formalism. The formalism is derived for energies above 100 MeV by fitting theoretical cross sections. Neutron absorption cross sections are represented by analytic expressions of similar form, but shape resonance phenomena of the Ramsauer effect is not present. Elastic differential cross sections are given as a renormalized impulse approximation. These cross section data bases are useful for nucleon transport applications.

  5. Quantitative infrared absorption cross sections of isoprene for atmospheric measurements

    SciTech Connect

    Brauer, Carolyn S.; Blake, Thomas A.; Guenther, Alex B.; Sharpe, Steven W.; Sams, Robert L.; Johnson, Timothy J.

    2014-11-19

    The OH- and O3- initiated oxidations of isoprene, which is one of the primary volatile organic compounds produced by vegetation, are a major source of atmospheric formaldehyde and other oxygenated organics, yet little quantitative IR data exists for isoprene. We thus report absorption coefficients and integrated band intensities for isoprene in the 600 - 6500 cm-1 region. The pressure-broadened (1 atmosphere N2) spectra were recorded at 278, 298 and 323 K in a 19.96 cm path length cell at 0.112 cm-1 resolution, using a Bruker 66V FTIR. Composite spectra are derived from a minimum of seven pressures at each temperature.

  6. Measurement of Two-Photon Absorption Cross Section of Metal Ions by a Mass Sedimentation Approach

    PubMed Central

    Ma, Zhuo-Chen; Chen, Qi-Dai; Han, Bing; Liu, Xue-Qing; Song, Jun-Feng; Sun, Hong-Bo

    2015-01-01

    The photo-reduction of metal ions in solution induced by femtosecond laser is an important and novel method for fabricating three-dimensional metal microstructures. However, the nonlinear absorption cross section of metal ions remains unknown because its measurement is difficult. In the present study, a method based on Two-Photon Excited Sedimentation (TPES) is proposed to measure the two-photon absorption cross section (TPACS) of metal ions in solution. The power-squared dependence of the amount of sediment on the excitation intensity was confirmed, revealing that 800 nm femtosecond laser induced reduction of metal ions was a two photon absorption process. We believe that the proposed method may be applied to measure the TPACS of several metal ions, thereby opening a new avenue towards future analysis of two-photon absorption materials. PMID:26657990

  7. Accurate universal parameterization of absorption cross sections III--light systems

    NASA Technical Reports Server (NTRS)

    Tripathi, R. K.; Cucinotta, F. A.; Wilson, J. W.

    1999-01-01

    Our prior nuclear absorption cross sections model [R.K. Tripathi, F.A. Cucinotta, J.W. Wilson, Nucl. Instr. and Meth. B 117 (1996) 347; R.K. Tripathi, J.W. Wilson, F.A. Cucinotta, Nucl. Instr. and Meth. B 129 (1997) 11] is extended for light systems (A < or = 4) where either both projectile and target are light particles or one is light particle and the other is medium or heavy nucleus. The agreement with experiment is excellent for these cases as well. Present work in combination with our original model provides a comprehensive picture of absorption cross sections for light, medium and heavy systems. As a result the extended model can reliably be used in all studies where there is a need for absorption cross sections.

  8. Improved measurement of the neutron absorption cross section for very low velocities

    NASA Astrophysics Data System (ADS)

    Schroffenegger, J.; Fierlinger, P.; Hollering, A.; Geltenbort, P.; Lauer, T.; Rauch, H.; Zechlau, T.

    2016-01-01

    The absorption cross section of natural Gd and isotopic enriched 157Gd for ultra-cold neutrons (UCN) as a function of the velocity has been measured within a time-of-flight-experiment. Particular attention is paid to small velocities in the region of a few m/s. This is intended to determine the validity of the 1 / v-law governing absorption cross sections in this region and the resulting divergence at v = 0. The experiment does not show any significant violation of 1 / v for v > 3 m /s.

  9. Equality between gravitational and electromagnetic absorption cross sections of extreme Reissner-Nordstroem black holes

    SciTech Connect

    Oliveira, Ednilton S.; Crispino, Luis C. B.; Higuchi, Atsushi

    2011-10-15

    The absorption cross section of Reissner-Nordstroem black holes for the gravitational field is computed numerically, taking into account the coupling of the electromagnetic and gravitational perturbations. Our results are in excellent agreement with low- and high-frequency approximations. We find equality between gravitational and electromagnetic absorption cross sections of extreme Reissner-Nordstroem black holes for all frequencies, which we explain analytically. This gives the first example of objects in general relativity in four dimensions that absorb the electromagnetic and gravitational waves in exactly the same way.

  10. Studies on mass energy-absorption coefficients and effective atomic energy-absorption cross sections for carbohydrates

    NASA Astrophysics Data System (ADS)

    Ladhaf, Bibifatima M.; Pawar, Pravina P.

    2015-04-01

    We measured here the mass attenuation coefficients (μ/ρ) of carbohydrates, Esculine (C15H16O9), Sucrose (C12H22O11), Sorbitol (C6H14O6), D-Galactose (C6H12O6), Inositol (C6H12O6), D-Xylose (C5H10O5) covering the energy range from 122 keV up to 1330 keV photon energies by using gamma ray transmission method in a narrow beam good geometry set-up. The gamma-rays were detected using NaI(Tl) scintillation detection system with a resolution of 8.2% at 662 keV. The attenuation coefficient data were then used to obtain the total attenuation cross-section (σtot), molar extinction coefficients (ε), mass-energy absorption coefficients (μen/ρ) and effective (average) atomic energy-absorption cross section (σa,en) of the compounds. These values are found to be in good agreement with the theoretical values calculated based on XCOM data.

  11. Cross section calculations of astrophysical interest. [for theories of absorption and emission lines

    NASA Technical Reports Server (NTRS)

    Gerjuoy, E.

    1974-01-01

    Cross sections are discussed for rotational excitation associated with theories of absorption and emission lines from molecules in space with emphasis on H2CO, CO, and OH by collisions with neutral particles such H, H2, and He. The sensitivity of the Thaddeus equation for the H2CO calculation is examined.

  12. Estimation of neutron energy for first resonance from absorption cross section for thermal neutrons

    NASA Technical Reports Server (NTRS)

    Bogart, Donald

    1951-01-01

    Examination of published data for some 52 isotopes indicates that the neutron energy for which the first resonance occurs is related to the magnitude of the thermal absorption cross section. The empirical relation obtained is in qualitative agreement with the results of a simplified version of the resonance theory of the nucleus of Breit-Wigner.

  13. Absolute UV absorption cross sections of dimethyl substituted Criegee intermediate (CH3)2COO

    NASA Astrophysics Data System (ADS)

    Chang, Yuan-Pin; Chang, Chun-Hung; Takahashi, Kaito; Lin, Jim-Min, Jr.

    2016-06-01

    The absolute absorption cross sections of (CH3)2COO under a jet-cooled condition were measured via laser depletion to be (1.32 ± 0.10) × 10-17 cm2 molecule-1 at 308 nm and (9.6 ± 0.8) × 10-18 cm2 molecule-1 at 352 nm. The peak UV cross section is estimated to be (1.75 ± 0.14) × 10-17 cm2 molecule-1 at 330 nm, according to the UV spectrum of (CH3)2COO (Huang et al., 2015) scaled to the absolute cross section at 308 nm.

  14. Systematic determination of absolute absorption cross-section of individual carbon nanotubes.

    PubMed

    Liu, Kaihui; Hong, Xiaoping; Choi, Sangkook; Jin, Chenhao; Capaz, Rodrigo B; Kim, Jihoon; Wang, Wenlong; Bai, Xuedong; Louie, Steven G; Wang, Enge; Wang, Feng

    2014-05-27

    Optical absorption is the most fundamental optical property characterizing light-matter interactions in materials and can be most readily compared with theoretical predictions. However, determination of optical absorption cross-section of individual nanostructures is experimentally challenging due to the small extinction signal using conventional transmission measurements. Recently, dramatic increase of optical contrast from individual carbon nanotubes has been successfully achieved with a polarization-based homodyne microscope, where the scattered light wave from the nanostructure interferes with the optimized reference signal (the reflected/transmitted light). Here we demonstrate high-sensitivity absorption spectroscopy for individual single-walled carbon nanotubes by combining the polarization-based homodyne technique with broadband supercontinuum excitation in transmission configuration. To our knowledge, this is the first time that high-throughput and quantitative determination of nanotube absorption cross-section over broad spectral range at the single-tube level was performed for more than 50 individual chirality-defined single-walled nanotubes. Our data reveal chirality-dependent behaviors of exciton resonances in carbon nanotubes, where the exciton oscillator strength exhibits a universal scaling law with the nanotube diameter and the transition order. The exciton linewidth (characterizing the exciton lifetime) varies strongly in different nanotubes, and on average it increases linearly with the transition energy. In addition, we establish an empirical formula by extrapolating our data to predict the absorption cross-section spectrum for any given nanotube. The quantitative information of absorption cross-section in a broad spectral range and all nanotube species not only provides new insight into the unique photophysics in one-dimensional carbon nanotubes, but also enables absolute determination of optical quantum efficiencies in important

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

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

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

  16. Temperature- and pressure-dependent absorption cross sections of gaseous hydrocarbons at 3.39 µm

    NASA Astrophysics Data System (ADS)

    Klingbeil, A. E.; Jeffries, J. B.; Hanson, R. K.

    2006-07-01

    The pressure- and temperature-dependent absorption cross sections of several neat hydrocarbons and multi-component fuels are measured using a 3.39 µm helium-neon laser. Absorption cross section measurements are reported for methane, ethylene, propane, n-heptane, iso-octane, n-decane, n-dodecane, JP-10, gasoline and jet-A with an estimated uncertainty of less than 3.5%. The experimental conditions range from 298 to 673 K and from 500 to 2000 Torr with nitrogen as the bath gas. An apparatus is designed to facilitate these measurements, and specific care is taken to ensure the compositional accuracy of the hydrocarbon/N2 mixtures. The absorption cross sections of the smallest hydrocarbons, methane and ethylene, vary with temperature and pressure. The cross sections of larger hydrocarbons show negligible dependence on pressure and only a weak dependence on temperature. The reported data increase the range of conditions and the number of hydrocarbons for which cross section measurements are available at the HeNe laser wavelength.

  17. O2 absorption cross sections /187-225 nm/ from stratospheric solar flux measurements

    NASA Astrophysics Data System (ADS)

    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.

  18. O2 absorption cross sections /187-225 nm/ from stratospheric solar flux measurements

    NASA Technical Reports Server (NTRS)

    Herman, J. R.; Mentall, J. E.

    1982-01-01

    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.

  19. Cavity-enhanced measurements of hydrogen peroxide absorption cross sections from 353 to 410 nm.

    PubMed

    Kahan, Tara F; Washenfelder, Rebecca A; Vaida, Veronica; Brown, Steven S

    2012-06-21

    We report near-ultraviolet and visible absorption cross sections of hydrogen peroxide (H(2)O(2)) using incoherent broad-band cavity-enhanced absorption spectroscopy (IBBCEAS), a recently developed, high-sensitivity technique. The measurements reported here span the range of 353-410 nm and extend published electronic absorption cross sections by 60 nm to absorption cross sections below 1 × 10(-23) cm(2) molecule(-1). We have calculated photolysis rate constants for H(2)O(2) in the lower troposphere at a range of solar zenith angles by combining the new measurements with previously reported data at wavelengths shorter than 350 nm. We predict that photolysis at wavelengths longer than those included in the current JPL recommendation may account for up to 28% of the total hydroxyl radical (OH) production from H(2)O(2) photolysis under some conditions. Loss of H(2)O(2) via photolysis may be of the same order of magnitude as reaction with OH and dry deposition in the lower atmosphere; these processes have very different impacts on HO(x) loss and regeneration.

  20. Measurements of the infrared absorption cross-sections of HCFC-141b (CH3CFCl2)

    NASA Astrophysics Data System (ADS)

    Le Bris, Karine; McDowell, James; Strong, Kimberly

    2012-10-01

    Detection of atmospheric trace gases by optical remote sensing techniques relies on the availability of molecular absorption spectra over a range of relevant temperatures. Absorption cross-sections of a pure vapour of the hydrochlorofluorocarbon HCFC-141b are reported at a resolution of 0.02 cm-1 for a range of temperatures between 223 and 283 K and a spectral range of 570-3100 cm-1. The integrated intensities of the nine main harmonic bands compare well with the data available from previous experimental studies and with theoretical calculations by ab initio and density functional theories.

  1. Parametric Study of the Absorption Cross-Section for a Moderately Conducting Thin Cylinder.

    NASA Astrophysics Data System (ADS)

    Gurton, Kristan Peter

    A system has been developed to measure the absorption cross section of a single carbon fiber at 35 GHz as a function of length, orientation, and diameter. Typical lengths considered ranged from 1 to 20 mm, and diameters ranged from 3 to 8 um. The results were compared with the modified integral equation calculations of Waterman and Pedersen that describe the scattering and absorption behavior for a wire of finite length and conductivity. Good agreement was found for all lengths, orientations, and diameters studied.

  2. Parametric study of the absorption cross section for a moderately conducting thin cylinder

    NASA Astrophysics Data System (ADS)

    Gurton, Kristan P.; Bruce, Charles W.

    1995-05-01

    A system has been developed to measure the absorption cross section for a single carbon fiber at 35 GHz as a function of length, orientation, and diameter. Typical lengths of the fibers considered ranged from 1 to 20 mm, and diameters ranged from 3 to 8 mu m. The results were compared with the modified integral equation calculations of Waterman and Pedersen that describe the scattering and absorption behavior for a wire of finite length and conductivity. Good agreement was found for all lengths, orientations, and diameters studied.

  3. Measurement of the two-photon absorption cross section by means of femtosecond thermal lensing.

    PubMed

    Rodriguez, Luis; Chiesa, Matteo

    2011-07-01

    We present a variation of the single-beam thermal lensing experiment to determine the two-photon absorption cross sections of classical fluorophores. The approach is based on comparison of two thermal lensing signals simultaneously induced by a one- and two-photon absorption process from a high-repetition-rate femtosecond laser system. As a consequence of this comparison, a simplified expression independent of the several experimental parameters is obtained. Additionally, because of the low incident power levels required, undesirable optical effects such as Kerr or Raman scattering are avoided. Our experimental results agree well with those recently published for luminescent methods, validating the approach.

  4. The influence of thermal aging on absorption phenomena in cross-linked polyethylene cable insulation

    NASA Astrophysics Data System (ADS)

    Borisova, M. E.; Osina, Yu. K.

    2017-01-01

    Absorption-controlled charge and discharge currents in cross-linked polyethylene (XPE) cable insulation before and after thermal aging have been measured. The experimental dependences were analyzed in terms of the equivalent Voigt scheme. Known parameters of the Voigt scheme were used to calculate the frequency dependences of relative dielectric permittivity, loss factor, and loss tangent of XPE films in the region of low frequencies (ω = 10-3-1 s-1) at high temperatures. Results of analysis of the absorption characteristics of XPE were applied to modeling of the process of thermal aging of cable insulation.

  5. Analysis of D-Region Absorption via HF Cross-Modulation Experiments at HAARP

    NASA Astrophysics Data System (ADS)

    Braun, E. M.; Moore, R. C.

    2010-12-01

    Experimental observations performed near the High-frequency Active Auroral Research Program (HAARP) HF transmitter in Gakona, Alaska are used to implement a new method quantifying the rate of absorption of HF radio waves in the D-region ionosphere. Quantifying the ambient and HF-modified characteristics of the D-region ionosphere in the vicinity of ionospheric HF heaters has historically proven to be a difficult task. For example, the electron density in the 60-90 km altitude range is typically too low to employ radio-sounding techniques; LIDAR observations typically require significant temporal averaging, precluding the investigation of physical processes that occur on sub-millisecond time scales; ELF/VLF wave generation experiments typically have difficulty providing reliable spatial resolution and also cannot experimentally distinguish between the spatial distribution of the ionospheric conductivity modulation produced by modulated HF heating and that of the current-driving electric fields associated with the auroral electrojet. Yet, the majority of HF signal absorption occurs in this region of the ionosphere, and the ability to characterize HF absorption in this region benefits a wide range of ionospheric HF heating experiments. The technique described and demonstrated in this paper combines ionosonde-style radio sounding with ELF/VLF cross-modulation experiments to identify the altitude of maximum D-region absorption as a function of HF frequency. Observations are presented and compared with the predictions of a theoretical model, demonstrating excellent agreement between experiment and theory and indicating that the technique may be used successfully in practice. Based on the success of this first experiment, another HF cross-modulation experiment has been performed at HAARP and analyzed theoretically. Pulsed-modulation experiments are used to assess the relative absorption as a function of altitude within the D-region ionosphere, and a method to chart the

  6. Determination of absorption cross-section of Si nanocrystals by two independent methods based on either absorption or luminescence

    SciTech Connect

    Valenta, J. Greben, M.; Remeš, Z.; Gutsch, S.; Hiller, D.; Zacharias, M.

    2016-01-11

    Absorption cross-section (ACS) of silicon nanocrystals (SiNCs) is determined via two completely independent approaches: (i) Excitation-intensity-dependent photoluminescence (PL) kinetics under modulated (long square pulses) pumping and (ii) absorbance measured by the photothermal deflection spectroscopy combined with morphology information obtained by the high-resolution transmission electron microscopy. This unique comparison reveals consistent ACS values around 10{sup −15} cm{sup 2} for violet excitation of SiNCs of about 3–5 nm in diameter and this value is comparable to most of direct band-gap semiconductor nanocrystals; however, it decreases steeply towards longer wavelengths. Moreover, we analyze the PL-modulation technique in detail and propose an improved experimental procedure which enables simpler implementation of this method to determine ACS of various (nano)materials in both solid and liquid states.

  7. Revealing spectral features in two-photon absorption spectrum of Hoechst 33342: a combined experimental and quantum-chemical study.

    PubMed

    Olesiak-Banska, Joanna; Matczyszyn, Katarzyna; Zaleśny, Robert; Murugan, N Arul; Kongsted, Jacob; Ågren, Hans; Bartkowiak, Wojciech; Samoc, Marek

    2013-10-10

    We present the results of wide spectral range Z-scan measurements of the two-photon absorption (2PA) spectrum of the Hoechst 33342 dye. The strongest 2PA of the dye in aqueous solution is found at 575 nm, and the associated two-photon absorption cross section is 245 GM. A weak but clearly visible 2PA band at ∼850 nm is also observed, a feature that could not be anticipated from the one-photon absorption spectrum. On the basis of the results of hybrid quantum mechanics/molecular mechanics calculations, we put forward a notion that the long-wavelength feature observed in the two-photon absorption spectrum of Hoechst 33342 is due to the formation of dye aggregates.

  8. Nucleon and heavy-ion total and absorption cross section for selected nuclei

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Costner, C. M.

    1975-01-01

    Approximate solutions of the coupled-channel equations for high-energy composite particle scattering are obtained and are applied to the nuclear scattering problem. Relationships between several approximation procedures are established and discussed. The eikonal formalism is used with a small-angle approximation to calculate the coherent elastic scattered amplitude from which total and absorption cross sections are derived. Detailed comparisons with nucleon-nucleus experiments show agreement within 5 percent except at lower energies where the eikonal approximation is of questionable accuracy. Even at these lower energies, agreement is within 15 percent. Tables of cross sections required for cosmic heavy-ion transport and shielding studies are presented.

  9. Temperature dependent absorption cross-sections of HNO3 and N2O5

    NASA Technical Reports Server (NTRS)

    Rattigan, Oliver V.; Harwood, Matthew H.; Jones, Rod L.; Cox, Richard A.

    1994-01-01

    Absorption cross-sections for HNO3 and N2O5 have been measured in the wavelength region 220-450 nm, using a dual beam diode array spectrometer with a spectral resolution of 0.3 nm. The results for both compounds are in good agreement with recommended values at room temperature. However, the cross-sections of both HNO3 and N2O5 show a marked reduction with decreasing temperature in the range 295-233 K. The calculated photolysis rate of HNO3 at the low temperatures and high solar zenith angles characteristic of the polar winter and spring is significantly lower than previously estimated.

  10. Accuracy of the correlation method of the thermal neutron absorption cross-section determination for rocks

    NASA Astrophysics Data System (ADS)

    Krynicka, Ewa

    1995-08-01

    The influence of various random errors on the accuracy of thermal neutron absorption cross-sections determined by a correlation method is discussed. It is considered either as an absolute accuracy, when all experimental errors arc taken into account, or as an experimental assay accuracy, when the reference moderator parameters are assumed as the invariant data fixed for all experiments. The estimated accuracy is compared with the accuracy of results obtained for the same rock sample by Czubek's measurement method.

  11. Kinetics of chromium ion absorption by cross-linked polyacrylate films

    NASA Technical Reports Server (NTRS)

    May, C. E.

    1984-01-01

    Three cross-linked ion exchange membranes were studied as to their ability to absorb chromium ion from aqueous chromium III nitrate solutions. Attention was given to the mechanism of absorption, composition of the absorbed product, and the chemical bonding. The membranes were: calcium polyacrylate, polyacrylic acid, and a copolymer of acrylic acid and vinyl alcohol. For the calcium polyacrylate and the copolymer, parabolic kinetics were observed, indicating the formation of a chromium polyacrylate phase as a coating on the membrane. The rate of absorption is controlled by the diffusion of the chromium ion through this coating. The product formed in the copolymer involves the formation of a coordination complex of a chromium ion with 6 carboxylic acid groups from the same molecule. The absorption of the chromium ion by the polyacrylic acid membranes appears to be more complicated, involving cross-linking. This is due to the coordination of the chromium ion with carboxylic acid groups from more than one polymer molecule. The absorption rate of the chromium ion by the calcium salt membrane was found to be more rapid than that by the free polyacrylic acid membrane.

  12. Effect of light state transitions on the apparent absorption cross section of Photosystem II in Chlorella

    SciTech Connect

    Falkowski, P.G.; Fujita, Yoshihiko

    1986-01-01

    The distribution of excitation energy between photosystems may profoundly affect the quantum yield of photosynthetic oxygen evolution. Excitation energy absorbed by pigment molecules is transferred to reaction centers, where it may potentially drive a photochemical event. To balance the photochemical events in PSII with those in PSI, excitation energy may be transferred between PSII and PSI. This type of energy transfer has been inferred primarily in the steady state quantum yield of oxygen evolution and/or fluorescence with changes in excitation wavelength. These so called ''state transitions'' have been attributed to changes in either the absorption cross section of PSII or ''spillover'' of excitation energy between the two photosystems. We report here on measurements of relative absorption cross sections of PSII under state I and state II light conditions. We simultaneously followed the yields of O/sub 2/ and the change in fluorescence yields, ..delta.. phi, as a function of flash energy using single turnover xenon flashes. Our data suggest that the effective absorption cross section of PSII does not change within +- 10% under physiological conditions in unpoisoned Chlorella pyrenoidosa. 13 refs., 3 figs.

  13. Measurements of absolute absorption cross sections of ozone in the 185- to 254-nm wavelength region and the temperature dependence

    NASA Technical Reports Server (NTRS)

    Yoshino, K.; Esmond, J. R.; Freeman, D. E.; Parkinson, W. H.

    1993-01-01

    Laboratory measurements of the relative absorption cross sections of ozone at temperatures 195, 228, and 295 K have been made throughout the 185 to 254 nm wavelength region. The absolute absorption cross sections at the same temperatures have been measured at several discrete wavelengths in the 185 to 250 nm region. The absolute cross sections of ozone have been used to put the relative cross sections on a firm absolute basis throughout the 185 to 255 nm region. These recalibrated cross sections are slightly lower than those of Molina and Molina (1986), but the differences are within a few percent and would not be significant in atmospheric applications.

  14. Thermal neutron absorption cross sections for igneous rocks: Newberry Caldera, Oregon

    SciTech Connect

    Lysne, P.

    1990-01-01

    The thermal neutron absorption cross sections of geologic materials are of first-order importance to the interpretation of pulsed neutron porosity logs and of second-order importance to the interpretation of steady-state porosity logs using dual detectors. Even in the latter case, uncertainties in log response can be excessive whenever formations are encountered that possess absorption properties appreciably greater than the limestones used in most tool calibrations. These effects are of importance to logging operations directed at geothermal applications where formation vary from igneous to sedimentary and which may contain solution-deposited minerals with very large cross-section values. Most measurements of cross-section values for geologic materials have been made for hydrocarbon production applications. Hence, the specimen materials are sedimentary and clean in the sense that they are not altered by geothermal fluids. This investigation was undertaken to measure cross-section values from a sequence of igneous materials obtained from a single hole drilled in an active hydrothermal system. 3 refs., 1 fig.

  15. Synthesis, crystals of centrosymmetric triphenylamine chromophores bearing prodigious two-photon absorption cross-section and biological imaging.

    PubMed

    Wang, Shichao; Xu, Shasha; Wang, Yiming; Tian, Xiaohe; Zhang, Yujin; Wang, Chuankui; Wu, Jieying; Yang, Jiaxiang; Tian, Yupeng

    2017-02-15

    Two centrosymmetric D-π-D type triphenylamine chromophores with long π-conjugated bridge and strong electron-donating moiety were designed, synthesized and fully characterized. The crystal analysis revealed that multiple CH⋯π interactions existed in two chromophores, which played a crucial role in generating molecular 1D chains and 2D layers structures. Linear and nonlinear optical properties of the chromophores were systematically investigated with the aid of theoretical calculations. Two chromophores both exhibited intense and wide-dispersed one-photon/two-photon excited fluorescence, bear prodigious 2PA cross section (δ). Especially for Dye2, with ethyoxyl groups, displayed the strong 2PA activity, large cross-sections (δmax>16,000GM) and high NLO efficiency (δmax/MW>16GM/(g·mol)) in the range of 680-830nm in DMF. In addition, one- and two-photon fluorescence microscopy images of HepG2 cells incubated with Dye2 were obtained and found that Dye2 could effectively uptake toward living cells and display a uniformly localized in cytosolic space.

  16. Synthesis, crystals of centrosymmetric triphenylamine chromophores bearing prodigious two-photon absorption cross-section and biological imaging

    NASA Astrophysics Data System (ADS)

    Wang, Shichao; Xu, Shasha; Wang, Yiming; Tian, Xiaohe; Zhang, Yujin; Wang, Chuankui; Wu, Jieying; Yang, Jiaxiang; Tian, Yupeng

    2017-02-01

    Two centrosymmetric D-π-D type triphenylamine chromophores with long π-conjugated bridge and strong electron-donating moiety were designed, synthesized and fully characterized. The crystal analysis revealed that multiple Csbnd H ⋯ π interactions existed in two chromophores, which played a crucial role in generating molecular 1D chains and 2D layers structures. Linear and nonlinear optical properties of the chromophores were systematically investigated with the aid of theoretical calculations. Two chromophores both exhibited intense and wide-dispersed one-photon/two-photon excited fluorescence, bear prodigious 2PA cross section (δ). Especially for Dye2, with ethyoxyl groups, displayed the strong 2PA activity, large cross-sections (δmax > 16,000 GM) and high NLO efficiency (δmax/MW > 16 GM/(g·mol)) in the range of 680-830 nm in DMF. In addition, one- and two-photon fluorescence microscopy images of HepG2 cells incubated with Dye2 were obtained and found that Dye2 could effectively uptake toward living cells and display a uniformly localized in cytosolic space.

  17. Overtone dissociation of peroxynitric acid (HO2NO2): absorption cross sections and photolysis products.

    PubMed

    Stark, Harald; Brown, Steven S; Burkholder, James B; Aldener, Mattias; Riffault, Veronique; Gierczak, Tomasz; Ravishankara, A R

    2008-10-02

    Band strengths for the second (3nuOH) and third (4nuOH) overtones of the OH stretch vibration of peroxynitric acid, HO2NO2 (PNA) in the gas-phase were measured using Cavity Ring-Down Spectroscopy (CRDS). Both OH overtone transitions show diffuse smoothly varying symmetrical absorption profiles without observable rotational structure. Integrated band strengths (base e) at 296 K were determined to be S(3nuOH) = (5.7 +/- 1.1) x 10(-20) and S(4nuOH) = (4.9 +/- 0.9) x 10(-21) cm(2) molecule(-1) cm(-1) with peak cross sections of (8.8 +/- 1.7) x 10(-22) and (7.0 +/- 1.3) x 10(-23) cm(2) molecule(-1) at 10086.0 +/- 0.2 cm(-1) and 13095.8 +/- 0.4 cm(-1), respectively, using PNA concentrations measured on line by Fourier-transform infrared and ultraviolet absorption spectroscopy. The quoted uncertainties are 2sigma (95% confidence level) and include estimated systematic errors in the measurements. OH overtone spectra measured at lower temperature, 231 K, showed a narrowing of the 3nuOH band along with an increase in its peak absorption cross section, but no change in S(3nuOH) to within the precision of the measurement (+/-9%). Measurement of a PNA action spectrum showed that HO2 is produced from second overtone photodissociation. The action spectrum agreed with the CRDS absorption spectra. The PNA cross sections determined in this work for 3nuOH and 4nuOH will increase calculated atmospheric photolysis rates of PNA slightly.

  18. Measurement of the ozone absorption cross-section at the 253. 7 nm Mercury line

    SciTech Connect

    Mauersberger, K.; Barnes, J.; Hanson, D.; Morton, J.

    1986-07-01

    The absorption cross-section of ozone at 253.7 nm is frequently used as a standard for the entire UV wavelength range. The presently accepted value is 1.147 x 10/sup -17/ cm/sup 2/, known with an uncertainty of about 2%. The cross-section has been recently measured by simultaneously monitoring the ozone pressure, the impurities in the ozone gas, the gas temperature and the UV beam intensity. The cross-section at room temperature was found to be 1.137 x 10/sup -17/ cm/sup 2/, having an uncertainty of +- .7%. The improved accuracy will aid a number of ozone experiments including the i-italicn-italic s-italici-italict-italicu-italic photometers and Solar Backscatter Ultraviolet instruments.

  19. Effective absorption cross sections and photolysis rates of anthropogenic and biogenic secondary organic aerosols

    NASA Astrophysics Data System (ADS)

    Romonosky, Dian E.; Ali, Nujhat N.; Saiduddin, Mariyah N.; Wu, Michael; Lee, Hyun Ji (Julie); Aiona, Paige K.; Nizkorodov, Sergey A.

    2016-04-01

    Mass absorption coefficient (MAC) values were measured for secondary organic aerosol (SOA) samples produced by flow tube ozonolysis and smog chamber photooxidation of a wide range of volatile organic compounds (VOC), specifically: α-pinene, β-pinene, β-myrcene, d-limonene, farnesene, guaiacol, imidazole, isoprene, linalool, ocimene, p-xylene, 1-methylpyrrole, and 2-methylpyrrole. Both low-NOx and high-NOx conditions were employed during the chamber photooxidation experiments. MAC values were converted into effective molecular absorption cross sections assuming an average molecular weight of 300 g/mol for SOA compounds. The upper limits for the effective photolysis rates of SOA compounds were calculated by assuming unity photolysis quantum yields and convoluting the absorption cross sections with a time-dependent solar spectral flux. A more realistic estimate for the photolysis rates relying on the quantum yield of acetone was also obtained. The results show that condensed-phase photolysis of SOA compounds can potentially occur with effective lifetimes ranging from minutes to days, suggesting that photolysis is an efficient and largely overlooked mechanism of SOA aging.

  20. Absorption cross section for the 5νOH stretch of acetic acid and peracetic acid

    NASA Astrophysics Data System (ADS)

    Begashaw, I. G.; Collingwood, M.; Bililign, S.

    2009-12-01

    We report measurements of the absorption cross sections for the vibrational O-H stretch (5νOH) overtone transitions in glacial acetic acid and peracetic acid. The photochemistry that results from overtone excitation has been shown to lead to OH radical production in molecules containing O-H (HNO3, H2O2). In addition the overtone excitation has been observed to result in light initiated chemical reaction. A Cavity ring-down spectroscopy (CRDS) instrument comprising of an Nd:YAG pumped dye laser and 620nm high reflectivity mirrors (R=99.995%) was used to measure the cross sections. The dye laser wavelength was calibrated using water vapor spectrum and the HITRAN 2008 database. The instrument’s minimum detectable absorption is αmin =4.5 *10-9cm-1 Hz-1/2 at 2σ noise level near the peak of the absorption feature. This measurement is the first for acetic acid at this excitation level. Preliminary results for acetic acid show the peak occurs near 615nm. Procedures for separating the monomer and dimer contribution will be presented. We would like to acknowledge support from NSF award #0803016 and NOAA-EPP award #NA06OAR4810187.

  1. Near-UV absorption cross sections and trans/cis equilibrium of nitrous acid

    SciTech Connect

    Bongartz, A.; Kames, J.; Welter, F.; Schurath, U. )

    1991-02-07

    The A {sup 1}A{double prime} {l arrow} X {sup 1}A{prime} absorption spectrum of gaseous nitrous acid has been measured in the 300-400-nm range. Absolute cross sections were determined by a combination of gas-phase and wet chemical analysis. The cross sections of prominent bands are 25% larger than the recommended values of Stockwell and Calvert. The influence of spectral resolution on absolute and differential absorption cross sections was also investigated. The integrated band area of the n{pi}* transition yields an oscillator strength f = (8.90 {plus minus} 0.36) {times} 10{sup {minus}4}, less than the reported liquid phase value of 2 {times} 10{sup {minus}3}. The equilibrium constant K = p{sub trans}/p{sub cis}, based on the assumption that the oscillator strength of the n{pi}* transition is the same for both rotamers, was found to be 3.25 {plus minus} 0.30 at 277 K. This yields an energy difference {Delta}E between trans- and cis-HONO of -2,700 J mol{sup {minus}1} in the electronic ground state, and -6,000 J mol{sup {minus}1} in the excited state.

  2. Uncertainty budgets of major ozone absorption cross sections used in UV remote sensing applications

    NASA Astrophysics Data System (ADS)

    Weber, Mark; Gorshelev, Victor; Serdyuchenko, Anna

    2016-09-01

    Detailed uncertainty budgets of three major ultraviolet (UV) ozone absorption cross-section datasets that are used in remote sensing application are provided and discussed. The datasets are Bass-Paur (BP), Brion-Daumont-Malicet (BDM), and the more recent Serdyuchenko-Gorshelev (SG). For most remote sensing application the temperature dependence of the Huggins ozone band is described by a quadratic polynomial in temperature (Bass-Paur parameterization) by applying a regression to the cross-section data measured at selected atmospherically relevant temperatures. For traceability of atmospheric ozone measurements, uncertainties from the laboratory measurements as well as from the temperature parameterization of the ozone cross-section data are needed as input for detailed uncertainty calculation of atmospheric ozone measurements. In this paper the uncertainty budgets of the three major ozone cross-section datasets are summarized from the original literature. The quadratic temperature dependence of the cross-section datasets is investigated. Combined uncertainty budgets is provided for all datasets based upon Monte Carlo simulation that includes uncertainties from the laboratory measurements as well as uncertainties from the temperature parameterization. Between 300 and 330 nm both BDM and SG have an overall uncertainty of 1.5 %, while BP has a somewhat larger uncertainty of 2.1 %. At temperatures below about 215 K, uncertainties in the BDM data increase more strongly than the others due to the lack of very low temperature laboratory measurements (lowest temperature of BDM available is 218 K).

  3. Absorption spectrum and absolute absorption cross sections of CH3O2 radicals and CH3I molecules in the wavelength range 7473-7497 cm(-1).

    PubMed

    Faragó, Eszter P; Viskolcz, Bela; Schoemaecker, Coralie; Fittschen, Christa

    2013-12-05

    The absorption spectrum of CH3O2 radicals and CH3I molecules has been measured in the range 7473-7497 cm(-1). CH3O2 radicals have been generated by 248 nm laser photolysis of CH3I in the presence of O2, and the relative absorption has been measured by time-resolved continuous-wave cavity ring-down spectroscopy (cw-CRDS). Calibration of the relative absorption spectrum has been carried out on three distinct wavelengths by carefully measuring CH3O2 decays under different experimental conditions and extracting the initial radical concentration (and with this the absolute absorption cross sections) by using the well-known rate constant for the CH3O2 self-reaction. The following, pressure-independent absorption cross sections were determined: 3.41 × 10(-20), 3.40 × 10(-20), and 2.11 × 10(-20) cm(2) at 7748.18, 7489.16, and 7493.33 cm(-1). These values are 2-3 times higher than previous determinations ( Pushkarsky, M. B.; Zalyubovsky, S. J.; Miller, T. A. J. Chem. Phys. 2000, 112 (24), 10695 - 10698 and Atkinson, D. B.; Spillman, J. L. J. Phys. Chem. A 2002, 106 (38), 8891 - 8902). The absorption spectrum of the stable precursor CH3I has also been determined and three characteristic sharp absorption lines with absorption cross sections up to 2 × 10(-21) cm(2) have been observed in this wavelength range.

  4. Absorption cross section determination of biogenic C5-aldehydes in the actinic region

    NASA Astrophysics Data System (ADS)

    Lanza, Beatriz; Jiménez, Elena; Ballesteros, Bernabé; Albaladejo, José

    2008-03-01

    UV absorption cross sections ( σλ) for 3-methylbutanal, trans-2-methyl-2-butenal, and 3-methyl-2-butenal have been determined between 255 and 390 nm and as a function of temperature (273-305 K). A D 2 lamp and a 0.5 m spectrograph coupled to a charged-couple device were employed in these measurements. σλ values were found to be independent of temperature in the range studied. The cross section data reported in this Letter were used to provide estimates of the photolysis rate coefficients ( Ji) for these compounds as a function of altitude in the troposphere. Photolysis and OH reaction both appear to be important in determining the atmospheric fate of these compounds.

  5. Cross-interference correction and simultaneous multi-gas analysis based on infrared absorption

    NASA Astrophysics Data System (ADS)

    Sun, You-Wen; Zeng, Yi; Liu, Wen-Qing; Xie, Pin-Hua; Chan, Ka-Lok; Li, Xian-Xin; Wang, Shi-Mei; Huang, Shu-Hua

    2012-09-01

    In this paper, we present simultaneous multiple pollutant gases (CO2, CO, and NO) measurements by using the non-dispersive infrared (NDIR) technique. A cross-correlation correction method is proposed and used to correct the cross-interferences among the target gases. The calculation of calibration curves is based on least-square fittings with third-order polynomials, and the interference functions are approximated by linear curves. The pure absorbance of each gas is obtained by solving three simultaneous equations using the fitted interference functions. Through the interference correction, the signal created at each filter channel only depends on the absorption of the intended gas. Gas mixture samples with different concentrations of CO2, CO, and NO are pumped into the sample cell for analysis. The results show that the measurement error of each gas is less than 4.5%.

  6. Absorption cross-sections of ozone in the ultraviolet and visible spectral regions: Status report 2015

    NASA Astrophysics Data System (ADS)

    Orphal, Johannes; Staehelin, Johannes; Tamminen, Johanna; Braathen, Geir; De Backer, Marie-Renée; Bais, Alkiviadis; Balis, Dimitris; Barbe, Alain; Bhartia, Pawan K.; Birk, Manfred; Burkholder, James B.; Chance, Kelly; von Clarmann, Thomas; Cox, Anthony; Degenstein, Doug; Evans, Robert; Flaud, Jean-Marie; Flittner, David; Godin-Beekmann, Sophie; Gorshelev, Viktor; Gratien, Aline; Hare, Edward; Janssen, Christof; Kyrölä, Erkki; McElroy, Thomas; McPeters, Richard; Pastel, Maud; Petersen, Michael; Petropavlovskikh, Irina; Picquet-Varrault, Benedicte; Pitts, Michael; Labow, Gordon; Rotger-Languereau, Maud; Leblanc, Thierry; Lerot, Christophe; Liu, Xiong; Moussay, Philippe; Redondas, Alberto; Van Roozendael, Michel; Sander, Stanley P.; Schneider, Matthias; Serdyuchenko, Anna; Veefkind, Pepijn; Viallon, Joële; Viatte, Camille; Wagner, Georg; Weber, Mark; Wielgosz, Robert I.; Zehner, Claus

    2016-09-01

    The activity "Absorption Cross-Sections of Ozone" (ACSO) started in 2008 as a joint initiative of the International Ozone Commission (IO3C), the World Meteorological Organization (WMO) and the IGACO ("Integrated Global Atmospheric Chemistry Observations") O3/UV subgroup to study, evaluate, and recommend the most suitable ozone absorption cross-section laboratory data to be used in atmospheric ozone measurements. The evaluation was basically restricted to ozone absorption cross-sections in the UV range with particular focus on the Huggins band. Up until now, the data of Bass and Paur published in 1985 (BP, 1985) are still officially recommended for such measurements. During the last decade it became obvious that BP (1985) cross-section data have deficits for use in advanced space-borne ozone measurements. At the same time, it was recognized that the origin of systematic differences in ground-based measurements of ozone required further investigation, in particular whether the BP (1985) cross-section data might contribute to these differences. In ACSO, different sets of laboratory ozone absorption cross-section data (including their dependence on temperature) of the group of Reims (France) (Brion et al., 1993, 1998, 1992, 1995, abbreviated as BDM, 1995) and those of Serdyuchenko et al. (2014), and Gorshelev et al. (2014), (abbreviated as SER, 2014) were examined for use in atmospheric ozone measurements in the Huggins band. In conclusion, ACSO recommends: The spectroscopic data of BP (1985) should no longer be used for retrieval of atmospheric ozone measurements. For retrieval of ground-based instruments of total ozone and ozone profile measurements by the Umkehr method performed by Brewer and Dobson instruments data of SER (2014) are recommended to be used. When SER (2014) is used, the difference between total ozone measurements of Brewer and Dobson instruments are very small and the difference between Dobson measurements at AD and CD wavelength pairs are diminished

  7. Pyrrolo[3,2-b]pyrroles – from unprecedented solvatofluorochromism to two-photon absorption

    PubMed Central

    Friese, Daniel H.; Mikhaylov, Alexander; Krzeszewski, Maciej; Poronik, Yevgen M.

    2015-01-01

    A combined experimental and theoretical study of the two-photon absorption properties of a series of quadrupolar molecules possessing a highly electron-rich heterocyclic core, pyrrolo[3,2-b]pyrrole is presented. In agreement with quantum-chemical calculations, we observe large two-photon absorption (2PA) cross-section values, σ2PA ~ 102–103 GM (1GM = 1050 cm4 s photon−1) at wavelengths 650–700 nm, corresponding to the 2-photon allowed but 1-photon forbidden transitions. The calculations also predict that increased planarity of this molecule via removal of two N-substituents leads to further increase in the σ2PA values. Surprisingly, the most quadrupolar pyrrolo[3,2-b]pyrrole derivative bearing two 4-nitrophenyl substituents at positions 2 and 5 demonstrates very strong solvatofluorochromic effect, with the fluorescence quantum yield as high as 0.96 in cyclohexane, while the fluorescence vanishes in DMSO. PMID:26511232

  8. Absorption cross section of building materials at mm wavelength in a reverberation chamber

    NASA Astrophysics Data System (ADS)

    Micheli, D.; Delfini, A.; Pastore, R.; Marchetti, M.; Diana, R.; Gradoni, G.

    2017-02-01

    The reverberation chamber (RC) method is used to estimate the average absorption cross section of building materials at mm wave frequencies. Analysed samples include concrete, travertine and bricks of different types. The investigation is carried out in the frequency range between 50 GHz and 68 GHz, which is of interest in the next generation of mobile telecommunication system. A cylindrical cavity is transformed into a RC through the use of a mechanical model stirrer. The chamber field is statistically homogeneous and depolarized; therefore it can be used to probe the average response of the sample under test. In particular, through a differential measure of the average quality factor (average insertion loss) it is possible estimate the fraction of power absorbed by the sample under test. Several cube-shape samples have been characterized and compared. Obtained results show that analysed samples have remarkably different levels of the electromagnetic wave absorption, depending on both material density and chemical composition. The absorption of pure water is used as a baseline to determine the dynamic range of the measurement.

  9. Absorption and scattering cross-section extinction values of silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Hlaing, May; Gebear-Eigzabher, Bellsabel; Roa, Azael; Marcano, Aristides; Radu, Daniela; Lai, Cheng-Yu

    2016-08-01

    We determine the extinction values of silver nanoparticles as a function of their diameter for three different wavelengths (405 nm, 532 nm, and 671 nm) from the values of absorbance and their photothermal lens response. We show that for particles of small diameters (<50 nm) the extinction grows as the cube of the diameter for all three wavelengths. For larger particles the extinction determined from absorbance exhibits a sixth order dependence on the diameters for 532 nm and 671 nm. This kind of behavior is typical of scattering processes that should dominate for large particles. For 405 nm the plasmonic resonant absorption dominates over scattering making difficult the observation of the sixth order dependence even for particles larger than 50 nm. The absorption cross-section measured by the photothermal method does not show the sixth order dependence. It depends on the cube of the particle's diameter for all nanoparticles confirming the scattering free character of this absorption technique and validating the results of the absorbance experiment.

  10. Method and apparatus for determination of temperature, neutron absorption cross section and neutron moderating power

    DOEpatents

    Vagelatos, Nicholas; Steinman, Donald K.; John, Joseph; Young, Jack C.

    1981-01-01

    A nuclear method and apparatus determines the temperature of a medium by injecting fast neutrons into the medium and detecting returning slow neutrons in three first energy ranges by producing three respective detection signals. The detection signals are combined to produce three derived indicia each systematically related to the population of slow neutrons returning from the medium in a respective one of three second energy ranges, specifically exclusively epithermal neutrons, exclusively substantially all thermal neutrons and exclusively a portion of the thermal neutron spectrum. The derived indicia are compared with calibration indicia similarly systematically related to the population of slow neutrons in the same three second energy ranges returning from similarly irradiated calibration media for which the relationships temperature, neutron absorption cross section and neutron moderating power to such calibration indicia are known. The comparison indicates the temperature at which the calibration indicia correspond to the derived indicia and consequently the temperature of the medium. The neutron absorption cross section and moderating power of the medium can be identified at the same time.

  11. (n,m)-Specific Absorption Cross Sections of Single-Walled Carbon Nanotubes Measured by Variance Spectroscopy.

    PubMed

    Sanchez, Stephen R; Bachilo, Sergei M; Kadria-Vili, Yara; Lin, Ching-Wei; Weisman, R Bruce

    2016-11-09

    A new method based on variance spectroscopy has enabled the determination of absolute absorption cross sections for the first electronic transition of 12 (n,m) structural species of semiconducting single-walled carbon nanotubes (SWCNTs). Spectrally resolved measurements of fluorescence variance in dilute bulk samples provided particle number concentrations of specific SWCNT species. These values were converted to carbon concentrations and correlated with resonant components in the absorbance spectrum to deduce (n,m)-specific absorption cross sections (absorptivities) for nanotubes ranging in diameter from 0.69 to 1.03 nm. The measured cross sections per atom tend to vary inversely with nanotube diameter and are slightly greater for structures of mod 1 type than for mod 2. Directly measured and extrapolated values are now available to support quantitative analysis of SWCNT samples through absorption spectroscopy.

  12. High resolution absorption cross-sections and band oscillator strengths of the Schumann-Runge absorption bands of isotopic oxygen, (0-16)(0-18), at 79 K

    NASA Technical Reports Server (NTRS)

    Yoshino, K.; Freeman, D. E.; Esmond, J. R.; Friedman, R. S.; Parkinson, W. H.

    1989-01-01

    Cross-sections of (0-16)(0-18) at 79 K have been obtained from photoabsorption measurements on mixtures of (0-16)2, (0-18)2, and (0-16)(0-18) at various pressures throughout the wavelength region 180.5-195.3 nm with a 6.65 m photoelectric scanning spectrometer equipped with a 2400 lines/mm grating and having an instrumental width (FWHM) of 0.0013 nm. The measured absorption cross-sections of the (0-16)(0-18) Schumann-Runge bands (11.0)-(3.0) are independent of the instrumental width. The measured cross-sections are presented graphically.

  13. Temperature effect on the two-photon absorption spectrum of all-trans-β-carotene.

    PubMed

    Vivas, M G; Mendonca, C R

    2012-07-05

    In this report, we investigate the influence of temperature on the two-photon absorption (2PA) spectrum of all-trans-β-carotene using the femtosecond white-light-continuum Z-scan technique. We observed that the 2PA cross-section decreases quadratically with the temperature. Such effect was modeled using a three-energy-level diagram within the sum-over-essential states approach, assuming temperature dependencies to the transition dipole moment and refractive index of the solvent. The results show that the transition dipole moments from ground to excited state and between the excited states, which governed the two-photon matrix element, have distinct behaviors with the temperature. The first one presents a quadratic dependence, while the second exhibits a linear dependence. Such effects were attributed mainly to the trans→cis thermal interconversion process, which decreases the effective conjugation length, contributing to diminishing the transition dipole moments and, consequently, the 2PA cross-section.

  14. The effective absorption cross-section of thermal neutrons in a medium containing strongly or weakly absorbing centres

    NASA Astrophysics Data System (ADS)

    Drozdowicz, Krzysztof; Gabańska, Barbara; Igielski, Andrzej; Krynicka, Ewa; Woźnicka, Urszula

    2003-06-01

    The structure of a heterogeneous system influences diffusion of thermal neutrons. The thermal-neutron absorption in grained media is considered in the paper. A simple theory is presented for a two-component medium treated as grains embedded in the matrix or as a system built of two types of grains (of strongly differing absorption cross-sections). A grain parameter is defined as the ratio of the effective macroscopic absorption cross-section of the heterogeneous medium to the absorption cross-section of the corresponding homogeneous medium (consisting of the same components in the same proportions). The grain parameter depends on the ratio of the absorption cross-sections and contributions of the components and on the size of grains. The theoretical approach has been verified in experiments on prepared dedicated models which have kept required geometrical and physical conditions (silver grains distributed regularly in Plexiglas). The effective absorption cross-sections have been measured and compared with the results of calculations. A very good agreement has been observed. In certain cases the differences between the absorption in the heterogeneous and homogeneous media are very significant. A validity of an extension of the theoretical model on natural, two-component, heterogeneous mixtures has been tested experimentally. Aqueous solutions of boric acid have been used as the strongly absorbing component. Fine- and coarse-grained pure silicon has been used as the second component with well-defined thermal-neutron parameters. Small and large grains of diabase have been used as the second natural component. The theoretical predictions have been confirmed in these experiments.

  15. High resolution absorption cross-sections and band oscillator strengths of the Schumann-Runge absorption bands of isotopic oxygen, (O-18)2, at 79 K

    NASA Technical Reports Server (NTRS)

    Yoshino, K.; Freeman, D. E.; Esmond, J. R.; Friedman, R. S.; Parkinson, W. H.

    1988-01-01

    Cross-sections of (O-18)2 at 79 K have been obtained from photoabsorption measurements at various pressures throughout the wavelength region 177.8-197.8 nm with a 6.65 m photoelectric scanning spectrometer equipped with a 2400 lines/mm grating and having an instrumental width (FWHM) of 0.0013 nm. The measured absorption cross-sections of the Schumann-Runge bands (14,0) through (2,0) are, with the exception of the (12,0) band, independent of the instrumental width. The measured cross-sections are presented graphically here and are available at wavenumber intervals of about 0.1/cm as numerical compilations stored on magnetic tape. Band oscillator strengths of those bands have been determined by direct numerical integration of the measured absolute cross-sections and are in excellent agreement with these theoretically calculated values.

  16. Stack emission monitoring using non-dispersive infrared with optimized nonlinear absorption cross-interference correction algorithm

    NASA Astrophysics Data System (ADS)

    Sun, Y.-W.; Liu, C.; Chan, K.-L.; Xie, P.-H.; Liu, W.-Q.; Zeng, Y.; Wang, S.-M.; Huang, S.-H.; Chen, J.; Wang, Y.-P.; Si, F.-Q.

    2013-02-01

    In this paper, we present an optimized analysis algorithm for non-dispersive infrared (NDIR) to monitor stack emissions. The newly developed analysis algorithm simultaneously compensates for nonlinear absorption and cross-interference between different gases. We present a mathematical derivation for the measurement error caused by variations in interference coefficients when nonlinear absorption occurs. The optimized algorithm is derived from a classical one and uses interference functions to quantify cross-interference. The interference functions vary proportionally with the nonlinear absorption. Thus, interference coefficients among different gases can be modeled by the interference functions whether gases are characterized by linear or nonlinear absorption. In this study, the simultaneous analysis of two components (CO2 and CO) serves as an example for the validation of the optimized algorithm. The interference functions in this case can be obtained by least-squares fitting with three-order polynomials. Experiments show that the results of cross-interference correction are improved significantly by utilizing fitted interference functions when nonlinear absorptions occur. The dynamic measurement ranges of CO2 and CO are improved by about a factor of 1.8 and 3.5, respectively. A commercial NDIR multi-gas analyzer with high accuracy was used to validate the CO and CO2 measurements derived from the NDIR analyzer prototype in which the new cross-interference correction algorithm was embedded. Both measurements well agreed.

  17. UV absorption cross-sections of phenol and naphthalene at temperatures up to 500 °C

    NASA Astrophysics Data System (ADS)

    Grosch, H.; Sárossy, Z.; Egsgaard, H.; Fateev, A.

    2015-05-01

    Absorption cross-sections and their temperature dependency, especially in the UV spectral range, of organic compounds such as phenol and naphthalene are of great interest in atmospheric research and high temperature processes. Due to the challenges of producing premixed gases of known concentration, it is difficult to determine absorption cross-sections in experiments, especially at higher temperatures. In this paper, a gas flow of nitrogen with a stable but unknown concentration of phenol or naphthalene is produced, and their UV absorption spectra between 195 and 350 nm have been measured at higher resolution than before (0.019 nm) in a hot gas flow cell at temperatures of up to 500 °C/773 K. A Petersen column is used to sample the organic compounds in the gas mixture to determine their concentration by GC-MS. The absorption cross-sections are calculated with the use of the Lambert-Beer law. Consequently, the absorption cross-sections for phenol and naphthalene at room temperature, 423 K, 573 K and 773 K in the range of 195-360 nm are presented in this study.

  18. New and improved infrared absorption cross sections for chlorodifluoromethane (HCFC-22)

    NASA Astrophysics Data System (ADS)

    Harrison, Jeremy J.

    2016-06-01

    The most widely used hydrochlorofluorocarbon (HCFC) commercially since the 1930s has been chloro-difluoromethane, or HCFC-22, which has the undesirable effect of depleting stratospheric ozone. As this molecule is currently being phased out under the Montreal Protocol, monitoring its concentration profiles using infrared sounders crucially requires accurate laboratory spectroscopic data. This work describes new high-resolution infrared absorption cross sections of chlorodifluoromethane over the spectral range 730-1380 cm-1, determined from spectra recorded using a high-resolution Fourier transform spectrometer (Bruker IFS 125HR) and a 26 cm pathlength cell. Spectra of chlorodifluoromethane/dry synthetic air mixtures were recorded at resolutions between 0.01 and 0.03 cm-1 (calculated as 0.9/MOPD; MOPD denotes the maximum optical path difference) over a range of temperatures and pressures (7.5-762 Torr and 191-295 K) appropriate for atmospheric conditions. This new cross-section dataset improves upon the one currently available in the HITRAN (HIgh-resolution TRANsmission) and GEISA (Gestion et Etude des Informations Spectroscopiques Atmosphériques) databases; in particular it provides coverage over a wider range of pressures and temperatures, has more accurate wavenumber scales, more consistent integrated band intensities, improved signal-to-noise, is free of channel fringing, and additionally covers the ν2 and ν7 bands.

  19. Kinetics of copper ion absorption by cross-linked calcium polyacrylate membranes

    NASA Technical Reports Server (NTRS)

    Philipp, W. H.; May, C. E.

    1983-01-01

    The absorption of copper ions from aqueous copper acetate solutions by cross-linked calcium acrylate membranes was found to obey parabolic kinetics similar to that found for oxidation of metals that form protective oxide layers. For pure calcium polyacrylate membranes the rate constant was essentially independent of copper acetate concentration and film thickness. For a cross-linked copolymer film of polyvinyl alcohol and calcium polyacrylate, the rate constant was much greater and dependent on the concentration of copper acetate. The proposed mechanism in each case involves the formation of a copper polyacrylate phase on the surface of the membrane. The diffusion of the copper ion through this phase appears to be the rate controlling step for the copolymer film. The diffusion of the calcium ion is apparently the rate controlling step for the calcium polyacrylate. At low pH, the copper polyacrylate phase consists of the normal copper salt; at higher pH, the phase appears to be the basic copper salt.

  20. Sensitivity analysis of neutron total and absorption cross sections within the optical model

    NASA Astrophysics Data System (ADS)

    Pigni, M. T.; Herman, M.; Obložinský, P.; Dietrich, F. S.

    2011-02-01

    Distinct maxima and minima in neutron total and absorption cross-section uncertainties when optical-model parameters are varied have been observed in large-scale covariance calculations. These features were seen over a wide mass range (20-210) and for energies up to 20 MeV. Here we investigate the physical origin of the observed patterns over an extended energy range (1 keV to 200 MeV). We have calculated the sensitivity of the cross sections for a specific nucleus (Fe56) to variations of the 15 parameters of a standard global optical potential parametrization, and have also carried out calculations for alternative global optical potentials over the original wide mass and energy ranges. We find that simple physical descriptions can be found in two energy ranges. Below approximately 100 keV, the patterns arise from the interplay of the s- and p-wave single-particle resonances. Above approximately 4 MeV, a single-phase-shift approximation (the Ramsauer model) describes the observed behavior. We discuss the potential importance of such sensitivity studies for further development of optical potentials.

  1. Cross two photon absorption in a silicon photonic crystal waveguide fiber taper coupler with a physical junction

    SciTech Connect

    Sarkissian, Raymond O'Brien, John

    2015-01-21

    Cross two photon absorption in silicon is characterized using a tapered fiber photonic crystal silicon waveguide coupler. There is a physical junction between the tapered fiber and the waveguide constituting a stand-alone device. This device is used to obtain the spectrum for cross two photon absorption coefficient per unit volume of interaction between photons of nondegenerate energy. The corresponding Kerr coefficient per unit volume of interaction is also experimentally extracted. The thermal resistance of the device is also experimentally determined and the response time of the device is estimated for on-chip all-optical signal processing and data transfer between optical signals of different photon energies.

  2. Comparison of x-ray absorption spectra between water and ice: New ice data with low pre-edge absorption cross-section

    SciTech Connect

    Sellberg, Jonas A.; Nilsson, Anders; Kaya, Sarp; Segtnan, Vegard H.; Chen, Chen; Tyliszczak, Tolek; Ogasawara, Hirohito; Nordlund, Dennis; Pettersson, Lars G. M.

    2014-07-21

    The effect of crystal growth conditions on the O K-edge x-ray absorption spectra of ice is investigated through detailed analysis of the spectral features. The amount of ice defects is found to be minimized on hydrophobic surfaces, such as BaF{sub 2}(111), with low concentration of nucleation centers. This is manifested through a reduction of the absorption cross-section at 535 eV, which is associated with distorted hydrogen bonds. Furthermore, a connection is made between the observed increase in spectral intensity between 544 and 548 eV and high-symmetry points in the electronic band structure, suggesting a more extended hydrogen-bond network as compared to ices prepared differently. The spectral differences for various ice preparations are compared to the temperature dependence of spectra of liquid water upon supercooling. A double-peak feature in the absorption cross-section between 540 and 543 eV is identified as a characteristic of the crystalline phase. The connection to the interpretation of the liquid phase O K-edge x-ray absorption spectrum is extensively discussed.

  3. Stack emission monitoring using non-dispersive infrared spectroscopy with an optimized nonlinear absorption cross interference correction algorithm

    NASA Astrophysics Data System (ADS)

    Sun, Y. W.; Liu, C.; Chan, K. L.; Xie, P. H.; Liu, W. Q.; Zeng, Y.; Wang, S. M.; Huang, S. H.; Chen, J.; Wang, Y. P.; Si, F. Q.

    2013-08-01

    In this paper, we present an optimized analysis algorithm for non-dispersive infrared (NDIR) to in situ monitor stack emissions. The proposed algorithm simultaneously compensates for nonlinear absorption and cross interference among different gases. We present a mathematical derivation for the measurement error caused by variations in interference coefficients when nonlinear absorption occurs. The proposed algorithm is derived from a classical one and uses interference functions to quantify cross interference. The interference functions vary proportionally with the nonlinear absorption. Thus, interference coefficients among different gases can be modeled by the interference functions whether gases are characterized by linear or nonlinear absorption. In this study, the simultaneous analysis of two components (CO2 and CO) serves as an example for the validation of the proposed algorithm. The interference functions in this case can be obtained by least-squares fitting with third-order polynomials. Experiments show that the results of cross interference correction are improved significantly by utilizing the fitted interference functions when nonlinear absorptions occur. The dynamic measurement ranges of CO2 and CO are improved by about a factor of 1.8 and 3.5, respectively. A commercial analyzer with high accuracy was used to validate the CO and CO2 measurements derived from the NDIR analyzer prototype in which the new algorithm was embedded. The comparison of the two analyzers show that the prototype works well both within the linear and nonlinear ranges.

  4. Difluorenyl carbo-Benzenes: Synthesis, Electronic Structure, and Two-Photon Absorption Properties of Hydrocarbon Quadrupolar Chromophores.

    PubMed

    Baglai, Iaroslav; de Anda-Villa, Manuel; Barba-Barba, Rodrigo M; Poidevin, Corentin; Ramos-Ortíz, Gabriel; Maraval, Valérie; Lepetit, Christine; Saffon-Merceron, Nathalie; Maldonado, José-Luis; Chauvin, Remi

    2015-09-28

    The synthesis, crystal and electronic structures, and one- and two-photon absorption properties of two quadrupolar fluorenyl-substituted tetraphenyl carbo-benzenes are described. These all-hydrocarbon chromophores, differing in the nature of the linkers between the fluorenyl substituents and the carbo-benzene core (C-C bonds for 3 a, C-C=C-C expanders for 3 b), exhibit quasi-superimposable one-photon absorption (1PA) spectra but different two-photon absorption (2PA) cross-sections σ2PA. Z-scan measurements (under NIR femtosecond excitation) indeed showed that the C≡C expansion results in an approximately twofold increase in the σ2PA value, from 336 to 656 GM (1 GM = 10(-50) cm(4) s molecule(-1) photon(-1)) at λ = 800 nm. The first excited states of Au and Ag symmetry accounting for 1PA and 2PA, respectively, were calculated at the TDDFT level of theory and used for sum-over-state estimations of σ2PA(λi), in which λi = 2 hc/Ei, h is Planck's constant, c is the speed of light, and Ei is the energy of the 2PA-allowed transition. The calculated σ2PA values of 227 GM at 687 nm for 3 a and 349 GM at 708 nm for 3 b are in agreement with the Z-scan results.

  5. Intrinsic radiative lifetime derived via absorption cross section of one-dimensional excitons

    PubMed Central

    Chen, Shaoqiang; Yoshita, Masahiro; Ishikawa, Akira; Mochizuki, Toshimitsu; Maruyama, Shun; Akiyama, Hidefumi; Hayamizu, Yuhei; Pfeiffer, Loren N.; West, Ken W.

    2013-01-01

    Intrinsic radiative lifetime is an essential physical property of low-dimensional excitons that represents their optical transition rate and wavefunction, which directly measures the probability of finding an electron and a hole at the same position in an exciton. However, the conventional method that is used to determine this property via measuring the temperature-dependent photoluminescence (PL) decay time involves uncertainty due to various extrinsic contributions at high temperatures. Here, we propose an alternative method to derive the intrinsic radiative lifetime via temperature-independent measurement of the absorption cross section and transformation using Einstein's A-B-coefficient equations derived for low-dimensional excitons. We experimentally verified our approach for one-dimensional (1D) excitons in high-quality 14 × 6 nm2 quantum wires by comparing it to the conventional approach. Both independent evaluations showed good agreement with each other and with theoretical predictions. This approach opens a promising path to studying low-dimensional exciton physics. PMID:23736905

  6. Level-crossing absorption with narrow spectral width in Rb vapor with buffer gas

    SciTech Connect

    Yu, Ye Jin; Lee, Hyun Jun; Bae, In-Ho; Moon, Han Seb; Noh, Heung-Ryoul

    2010-02-15

    We present the transformation in the Hanle configuration of the transmission that results from coherent population trapping (CPT) into the level-crossing absorption (LCA) that results from the single-photon optical pumping in the {sup 87}Rb D{sub 1} line of a Rb vapor cell with a Ne buffer gas when the polarization of the laser field is changed from linear to circular. The LCA spectrum, with a narrow spectral width of 2.4 mG (1.7 kHz), was observed in the F{sub g{yields}}F{sub e{<=}}F{sub g} transition with the circularly polarized laser. This may be because the LCA is both related to the transverse magnetic field and the atom-laser interaction time resulting from diffusive atomic motion in the cell with the buffer gas. The CPT and LCA spectra were calculated numerically using the full density matrix equations for the relevant magnetic sublevels of the hyperfine levels, considering the residual magnetic fields perpendicular to laser propagation and the collision effects resulting from the buffer gas. There was good qualitative agreement between theoretical and experimental results.

  7. First-principles calculation of multiphoton absorption cross section of α-quartz under femtosecond laser irradiation

    NASA Astrophysics Data System (ADS)

    Yu, Dong; Jiang, Lan; Wang, Feng; Qu, Liangti; Lu, Yongfeng

    2016-05-01

    Time-dependent density functional theory-based first-principles calculations have been used to study the ionization process and electron excitation. The results show that the number of excited electrons follows the power law σ k I k at peak intensities of I < 5 × 1013 W/cm2, indicating that the multiphoton ionization plays a key role. The multiphoton absorption cross section of α-quartz σ k is further calculated to be 3.54 × 1011 cm-3 ps-1 (cm2/TW)6. Using the plasma model, the theoretical results of the damage threshold fluences are consistent with the experimental data, which validates the calculated value of multiphoton absorption cross section. By employing the calculated cross section value in the plasma model, the damage threshold fluences are theoretically estimated, being consistent with the experimental data, which validates the calculated value of multiphoton absorption cross section. The preliminary multiscale model shows great potential in the simulation of laser processing.

  8. Near IR two photon absorption of cyanines dyes: application to optical power limiting at telecommunication wavelengths

    NASA Astrophysics Data System (ADS)

    Bouit, Pierre-Antoine; Wetzel, Guillaume; Feneyrou, Patrick; Bretonnière, Yann; Kamada, Kenji; Maury, Olivier; Andraud, Chantal

    2008-02-01

    The design and synthesis of symmetrical and unsymmetrical heptamethine cyanines is reported. These chromophores present significant two-photon cross section in the 1400-1600 nm spectral range. In addition, they display optical power limiting (OPL) properties. OPL curves were interpreted on the basis of two-photon absorption (2PA) followed by excited state absorption (ESA). Finally, these molecules present several relevant properties (nonlinear absorption properties, two-step gram scale synthesis, high solubility, good thermal stability), which could lead to numerous practical applications in material science (solid state optical limiting, signal processing) or in biology (imaging).

  9. HALO GAS CROSS SECTIONS AND COVERING FRACTIONS OF Mg II ABSORPTION SELECTED GALAXIES

    SciTech Connect

    Kacprzak, Glenn G.; Churchill, Christopher W.; Steidel, Charles C.; Murphy, Michael T. E-mail: cwc@nmsu.edu E-mail: mmurphy@astro.swin.edu.au

    2008-03-15

    We examine halo gas cross sections and covering fractions, f{sub c} , of intermediate-redshift Mg II absorption selected galaxies. We computed statistical absorber halo radii, R{sub x}, using current values of dN/dz and Schechter luminosity function parameters, and have compared these values to the distribution of impact parameters and luminosities from a sample of 37 galaxies. For equivalent widths W{sub r}(2796) {>=} 0.3 A, we find 43 {<=} R{sub x} {<=} 88 kpc, depending on the lower luminosity cutoff and the slope, {beta}, of the Holmberg-like luminosity scaling, R {proportional_to} L{sup {beta}}. The observed distribution of impact parameters, D, are such that several absorbing galaxies lie at D>R{sub x} and several non-absorbing galaxies lie at D < R{sub x}. We deduced that f{sub c} must be less than unity and obtain a mean of {approx} 0.5 for our sample. Moreover, the data suggest that halo radii of Mg II absorbing galaxies do not follow a luminosity scaling with {beta} in the range of 0.2-0.28, if f{sub c} = 1 as previously reported. However, provided f{sub c} {approx} 0.5, we find that halo radii can remain consistent with a Holmberg-like luminosity relation with {beta} {approx_equal} 0.2 and R{sub *}= R{sub x}/{radical}(f{sub c}){approx}110 kpc. No luminosity scaling ({beta} = 0) is also consistent with the observed distribution of impact parameters if f{sub c} {<=} 0.37. The data support a scenario in which gaseous halos are patchy and likely have non-symmetric geometric distributions about the galaxies. We suggest that halo gas distributions may not be governed primarily by galaxy mass/luminosity but also by stochastic processes local to the galaxy.

  10. Low frequency absorption properties of a thin metamaterial absorber with cross-array on the surface of a magnetic substrate

    NASA Astrophysics Data System (ADS)

    Chen, Qian; Bie, Shaowei; Yuan, Wei; Xu, Yongshun; Xu, Haibing; Jiang, Jianjun

    2016-10-01

    The design, fabrication, and measurement of a metamaterial with broadband microwave absorption properties in the low frequency range are presented in this paper. The metamaterial has a layered structure with a thickness of 2.2 mm, and consists of a conventional printed circuit board (PCB) process fabricated cross array on the surface of a flake-shaped carbonyl iron (CI) powder-filled silicon rubber composite magnetic substrate backed by a metal plane. The measurement results indicate that the absorption bandwidth (defined as the frequency range with reflection coefficient below  -10 dB) of the proposed structure is 2.55 GHz-5.68 GHz. The power loss mechanism was outlined according to the current distribution on and off the resonance frequency. Moreover, the absorption performance of the proposed structure for incident angles ranging from 0° to 60° for both transverse electric (TE) wave and transverse magnetic (TM) waves were exhibited.

  11. New High-Resolution Absorption Cross-Section Measurements of HCFC-142B in the Mid-Ir

    NASA Astrophysics Data System (ADS)

    Le Bris, Karine; Strong, Kimberly; Melo, Stella

    2009-06-01

    HCFC-142b (1-chloro-1,1-difluoroethane) is a temporary substitute for ozone-depleting chlorofluorocarbons (CFCs). However, due to its high absorption cross-sections in the mid-IR, HCFC-142b is also a highly potent greenhouse gas, now detectable from space by satellite missions. So far, the accuracy of the retrieval has been limited by the lack of reference data in a range of temperatures compatible with atmospheric observations. We present new absorption cross section measurements of HCFC-142b at high-resolution (0.02 cm^{-1}) from 223 K to 283 K in the 600 cm^{-1}- 4000 cm^{-1} spectral window. The composite spectra are calculated for each temperature from a set of acquisitions at different pressures by Fourier transform spectroscopy.

  12. High resolution absorption cross sections for the A2Pi-X2Pi system of ClO

    NASA Technical Reports Server (NTRS)

    Wine, P. H.; Ravishankara, A. R.; Philen, D. L.; Davis, D. D.; Watson, R. T.

    1977-01-01

    High-resolution ultraviolet absorption cross-sections for the ClO molecule are obtained, with the aim of facilitating studies of ozone depletion resulting from the injection of chlorofluorocarbons into the atmosphere. The spectroscopic analysis, which involves a frequency-doubled tunable dye laser with a bandwidth of 0.015 A, is described. Studies of the rotational lines of the ClO A 2Pi 3/2-X2Pi 3/2 9-10 band were conducted. Peak cross-sections for the P and R lines of the 9-0 band are found to be 10.0, 9.6, 8.6, 10.6, 10.3, and 9.2 times ten to the negative seventeenth power cm squared, with estimated accuracy of plus or minus 25%. Problems in distinguishing between Cl-35 and Cl-37 absorption are also considered.

  13. Absolute excited-state absorption cross section and fluorescence quantum efficiency of Cr/sup 3 +/: gadolinium scandium gallium garnet

    SciTech Connect

    Seelert, W.; Strauss, E.

    1987-10-01

    Excited-state properties of the laser material Cr/sup 3 +/:Gd/sub 3/Sc/sub 2/(GaO/sub 4/)/sub 3/ were determined by a photocaloric technique. The excited-state absorption cross section at 650 nm is (3.6 +- 0.6)10/sup -20/ cm/sup 2/, and the fluorescence quantum efficiency at ambient temperature is (91 +- 1)%.

  14. Measurements of the absorption cross section of (13)CHO(13)CHO at visible wavelengths and application to DOAS retrievals.

    PubMed

    Goss, Natasha R; Waxman, Eleanor M; Coburn, Sean C; Koenig, Theodore K; Thalman, Ryan; Dommen, Josef; Hannigan, James W; Tyndall, Geoffrey S; Volkamer, Rainer

    2015-05-14

    The trace gas glyoxal (CHOCHO) forms from the atmospheric oxidation of hydrocarbons and is a precursor to secondary organic aerosol. We have measured the absorption cross section of disubstituted (13)CHO(13)CHO ((13)C glyoxal) at moderately high (1 cm(-1)) optical resolution between 21 280 and 23 260 cm(-1) (430-470 nm). The isotopic shifts in the position of absorption features were found to be largest near 455 nm (Δν = 14 cm(-1); Δλ = 0.29 nm), whereas no significant shifts were observed near 440 nm (Δν < 0.5 cm(-1); Δλ < 0.01 nm). These shifts are used to investigate the selective detection of (12)C glyoxal (natural isotope abundance) and (13)C glyoxal by in situ cavity enhanced differential optical absorption spectroscopy (CE-DOAS) in a series of sensitivity tests using synthetic spectra, and laboratory measurements of mixtures containing (12)C and (13)C glyoxal, nitrogen dioxide, and other interfering absorbers. We find the changes in apparent spectral band shapes remain significant at the moderately high optical resolution typical of CE-DOAS (0.55 nm fwhm). CE-DOAS allows for the selective online detection of both isotopes with detection limits of ∼200 pptv (1 pptv = 10(-12) volume mixing ratio), and sensitivity toward total glyoxal of few pptv. The (13)C absorption cross section is available for download from the Supporting Information.

  15. Absorption-Dominated Electromagnetic Wave Suppressor Derived from Ferrite-Doped Cross-Linked Graphene Framework and Conducting Carbon.

    PubMed

    Biswas, Sourav; Arief, Injamamul; Panja, Sujit Sankar; Bose, Suryasarathi

    2017-01-25

    To minimize electromagnetic (EM) pollution, two key parameters, namely, intrinsic wave impedance matching and intense absorption of incoming EM radiation, must satisfy the utmost requirements. To target these requirements, soft conducting composites consisting of binary blends of polycarbonate (PC) and poly(vinylidene fluoride) (PVDF) were designed with doped multiwalled carbon nanotubes (MWCNTs) and a three-dimensional cross-linked graphene oxide (GO) framework doped with ferrite nanoparticles. The doping of α-MnO2 onto the MWCNTs ensured intrinsic wave impedance matching in addition to providing conducting pathways, and the ferrite-doped cross-linked GO facilitated the enhanced attenuation of the incoming EM radiation. This unique combination of magnetodielectric coupling led to a very high electromagnetic shielding efficiency (SE) of -37 dB at 18 GHz, dominated by absorption-driven shielding. The promising results from the composites further motivated us to rationally stack individual composites into a multilayer architecture following an absorption-multiple reflection-absorption pathway. This resulted in an impressive SE of -57 dB for a thin shield of 0.9-mm thickness. Such a high SE indicates >99.999% attenuation of the incoming EM radiation, which, together with the improvement in structural properties, validates the potential of these materials in terms of applications in cost-effective and tunable solutions.

  16. EMPIRICAL LINE LISTS AND ABSORPTION CROSS SECTIONS FOR METHANE AT HIGH TEMPERATURES

    SciTech Connect

    Hargreaves, R. J.; Bernath, P. F.; Dulick, M.; Bailey, J.

    2015-11-01

    Hot methane is found in many “cool” sub-stellar astronomical sources including brown dwarfs and exoplanets, as well as in combustion environments on Earth. We report on the first high-resolution laboratory absorption spectra of hot methane at temperatures up to 1200 K. Our observations are compared to the latest theoretical spectral predictions and recent brown dwarf spectra. The expectation that millions of weak absorption lines combine to form a continuum, not seen at room temperature, is confirmed. Our high-resolution transmittance spectra account for both the emission and absorption of methane at elevated temperatures. From these spectra, we obtain an empirical line list and continuum that is able to account for the absorption of methane in high temperature environments at both high and low resolution. Great advances have recently been made in the theoretical prediction of hot methane, and our experimental measurements highlight the progress made and the problems that still remain.

  17. Effects of crossed electric and magnetic fields on the interband optical absorption spectra of variably spaced semiconductor superlattices

    NASA Astrophysics Data System (ADS)

    Zuleta, J. N.; Reyes-Gómez, E.

    2016-05-01

    The interband optical absorption spectra of a GaAs-Ga1-xAlxAs variably spaced semiconductor superlattice under crossed in-plane magnetic and growth-direction applied electric fields are theoretically investigated. The electronic structure, transition strengths and interband absorption coefficients are analyzed within the weak and strong magnetic-field regimes. A dramatic quenching of the absorption coefficient is observed, in the weak magnetic-field regime, as the applied electric field is increased, in good agreement with previous experimental measurements performed in a similar system under growth-direction applied electric fields. A decrease of the resonant tunneling in the superlattice is also theoretically obtained in the strong magnetic-field regime. Moreover, in this case, we found an interband absorption coefficient weakly dependent on the applied electric field. Present theoretical results suggest that an in-plane magnetic field may be used to tune the optical properties of variably spaced semiconductor superlattices, with possible future applications in solar cells and magneto-optical devices.

  18. Absolute absorption cross sections of ozone at 300 K, 228 K and 195 K in the wavelength region 185-240 nm

    NASA Technical Reports Server (NTRS)

    Yoshino, K.; Parkinson, W. H.; Freeman, D. E.

    1992-01-01

    An account is given of progress of work on absorption cross section measurements of ozone at 300 K, 228 K and 195 K in the wavelength region 185-240 nm. In this wavelength region, the penetration of solar radiation into the Earth's atmosphere is controlled by O2 and O3. The transmitted radiation is available to dissociate trace species such as halocarbons and nitrous oxide. We have recently measured absolute absorption cross sections of O3 in the wavelength region 240-350 nm (Freeman et al., 1985; Yoshino et al., 1988). We apply these proven techniques to the determination of the absorption cross section of O3 at 300 K, 228 K and 195 K throughout the wavelength region 185-240 nm. A paper titled 'Absolute Absorption Cross Section Measurements of Ozone in the Wavelength Region 185-254 nm and the Temperature Dependence' has been submitted for publication in the Journal of Geophysical Research.

  19. Absorption enhancement by matching the cross-section of plasmonic nanowires to the field structure of tightly focused beams.

    PubMed

    Normatov, Alexander; Spektor, Boris; Leviatan, Yehuda; Shamir, Joseph

    2011-04-25

    Nanostructured materials, designed for enhanced light absorption, are receiving increased scientific and technological interest. In this paper we propose a physical criterion for designing the cross-sectional shape of plasmonic nanowires for improved absorption of a given tightly focused illumination. The idea is to design a shape which increases the matching between the nanowire plasmon resonance field and the incident field. As examples, we design nanowire shapes for two illumination cases: a tightly focused plane wave and a tightly focused beam containing a line singularity. We show that properly shaped and positioned silver nanowires that occupy a relatively small portion of the beam-waist area can absorb up to 65% of the total power of the incident beam.

  20. Evaluation of the use of five laboratory determined ozone absorption cross sections in brewer and dobson retrieval algorithms

    NASA Astrophysics Data System (ADS)

    Redondas, A.; Evans, R.; Stuebi, R.; Köhler, U.; Weber, M.

    2013-09-01

    The primary ground-based instruments used to report total column ozone (TOC) are Brewer and Dobson Spectrophotometers, in separate networks. These instruments make measurements of the UV irradiances, and through a well-defined process a TOC value is produced. Inherent in the algorithm is the use of a laboratory determined cross-section data set. We used five ozone cross section data sets: three Bass and Paur, Daumont, Malicet and Brion (DMB) and a new Institute of Environmental Physics (IUP), University of Bremen, set. The three Bass and Paur (1985) sets are: quadratic temperature coefficients from IGACO web page (IGQ4), the Brewer network operational calibration set (BOp), and the set used by Bernhard et al. (2005), in the reanalysis of the Dobson absorption coefficient values (B05). The ozone absorption coefficients for Brewer and Dobson are then calculated using the normal Brewer operative method which is essentially the same as used on Dobson. Considering the standard TOC algorithm for the Brewer instruments and comparing to the Brewer standard operational calibration data set, using the slit functions for the individual instruments: we find the UIP data set changes the calculated TOC by -0.5%, the DBM data set changes the calculate TOC by -3.2%, and the IGQ4 data set at -45 °C changes the calculated TOC by +1.3%. Considering the standard algorithm for the Dobson instruments, and comparing to results using the official 1992 ozone absorption coefficients values and the single set of slit functions defined for all Dobson instruments, the calculated TOC changes by +1%, with little variation depending on which data set is used We applied the changes to the European Dobson and Brewer reference instruments during the Izaña 2012 Absolute Calibration Campaign. The application of a common Langley calibration and the IUP cross section the differences between Brewer and Dobson vanish whereas using Bass and Paur and DBM produce differences of 1.5% and 2% respectively. A

  1. Rotationally inelastic scattering in CH4+He, Ne, and Ar: State-to-state cross sections via direct infrared laser absorption in crossed supersonic jets

    NASA Astrophysics Data System (ADS)

    Chapman, William B.; Schiffman, Aram; Hutson, Jeremy M.; Nesbitt, David J.

    1996-09-01

    Absolute integral state-to-state cross sections are reported for rotationally inelastic scattering in crossed jets of CH4 with the rare gases He, Ne, Ar, at center of mass collision energies of 460±90, 350±70, and 300±60 cm-1, respectively. CH4 seeded in Ar buffer gas is cooled in a pulsed supersonic expansion into the three lowest rotational levels allowed by nuclear spin statistics corresponding to A(J=0), F(J=1), and E(J=2) symmetry. Rotational excitation occurs in single collisions with rare gas atoms from a second pulsed supersonic jet. The column integrated densities of CH4 in both initial and final scattering states are subsequently probed in the jet intersection region via direct absorption of light from a narrow bandwidth (0.0001 cm-1), single mode color center laser. Total inelastic cross sections for collisional loss out of the J=0, 1, and 2 methane states are determined in absolute units from the linear decrease of infrared absorption signals as a function of collider gas concentration. Tuning of the ir laser source also permits probing of the collisionally excited rotational states with quantum state and velocity resolution; column integrated scattering densities are measured for all energetically accessible final states and used to infer absolute inelastic cross sections for state-to-state energy transfer. The observed trends are in good qualitative agreement with quantum state resolved pressure broadening studies; however, the dependences of the rotationally inelastic cross sections on nuclear spin modification (i.e., J) and rotational inelasticity (i.e., ΔJ) is not well predicted by conventional angular momentum or energy gap models. More rigorous comparison with the quantum state-resolved scattering data is obtained from full close coupled scattering calculations on trial potential energy surfaces by Buck and co-workers [Chem. Phys. Lett. 98, 199 (1983); Mol. Phys. 55, 1233, 1255 (1985)] for each of the three CH4+rare gas systems. Agreement

  2. A TDDFT investigation of bay substituted perylenediimides: absorption and intersystem crossing.

    PubMed

    Quartarolo, Angelo Domenico; Chiodo, Sandro Giuseppe; Russo, Nino

    2012-04-30

    The conformational structure and electronic spectra properties of a series of bay substituted perylenediimides (PDI) derivatives have been investigated by means of density functional theory (DFT) and time-dependent DFT. The B3LYP and PBE0 hybrid exchange-correlation functionals were applied in conjunction with the double-ζ quality SVP basis set. These compounds are interesting for organic materials science and as photosensitizers in cancer phototherapy (PDT), because of their intense absorption in the visible region. Results show that the substitution at the bay position of the PDI parent molecule with N-alkyl groups shifts the absorption maxima towards the red part of the visible spectrum (around 650-700 nm) as required for the applications in PDT. The main PDT action mechanisms have been investigated by computing of electron affinities, ionization potentials, triplet energies and spin-orbit matrix elements between singlet and triplet excited states.

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

    NASA Technical Reports Server (NTRS)

    Pliutau, Denis; Prasad, Narasimha S

    2013-01-01

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

  4. Measurements of the Thermal Neutron Macroscopic Absorption Cross Section for Neutron Absorbing Layers

    NASA Astrophysics Data System (ADS)

    Kiyani, Abouzar; Rostam, G. Gh.; Sadat Kiai, S. M.; Bakhsh, Hossin Jahan; Mahdavi, Farzad

    2011-12-01

    Objective of this study is measuring the macroscopic cross section of a neutron absorbing layer for thermal neutrons. For this purpose a neutron source and BF 3 detector have been applied. For measuring macroscopic cross section of thermal neutrons by the Formula, it is necessary to provide suitable geometric conditions in order to assume the production and build-up coefficient to be the unit value (=1). To fulfill required conditions for this assumption, surface of the detector is covered with a 2 mm thick layer of cadmium. Radiation window of the detector has a 3 cm diameter, situated directly in front of the source. By placing the cadmium cover over the detector, variation of values verses thickness of absorbent layer, renders linear function behavior, making it possible to measure the macroscopic cross section. The next stage is applying the MCNP code by simulating F1 tally and cosine-cards for calculating Total Macroscopic Cross-Section. Validation of this study is achieved through comparison of simulation by the MCNP code and results rendered by experiment measurements.

  5. High resolution absorption cross sections in the transmission window region of the Schumann-Runge bands and Herzberg continuum of O2

    NASA Technical Reports Server (NTRS)

    Yoshino, K.; Esmond, J. R.; Cheung, A. S.-C.; Freeman, D. E.; Parkinson, W. H.

    1992-01-01

    Results are presented on measurements, conducted in the wavelength region 180-195 nm, and at different pressures of oxygen (between 2.5-760 torr) in order to separate the pressure-dependent absorption from the main cross sections, of the absorption cross sections of the Schumann-Runge bands in the window region between the rotational lines of S-R bands of O2. The present cross sections supersede the earlier published cross sections (Yoshino et al., 1983). The combined cross sections are presented graphically; they are available at wavenumber intervals of about 0.1/cm from the National Space Science Data Center. The Herzberg continuum cross sections are derived after subtracting calculated contributions from the Schumann-Runge bands. These are significantly smaller than any previous measurements.

  6. One- and two-photon absorption of fluorescein dianion in water: a study using S-QM/MM methodology and ZINDO method.

    PubMed

    Silva, D L; Barreto, R C; Lacerda, E G; Coutinho, K; Canuto, S

    2014-02-05

    One- and two-photon absorption (1PA and 2PA) of fluorescein dianion (FSD) in water were studied using a combined and sequential Quantum Mechanics/Molecular Dynamics methodology. Different sets of 250 statistically relevant (uncorrelated) configurations composed by the solute and several solvent molecules were sampled from the classical simulation. On these configurations, the electronic properties were calculated a posteriori using the Zerner's intermediate neglect of differential overlap (ZINDO) method. The linear and nonlinear absorption of FSD in water were calculated using discrete and explicit solvent models. In the largest case, the relevant configurations are composed by FSD and 47 explicit water molecules embedded in the electrostatic field of all remaining water molecules. Both INDO/CIS and INDO/CISD calculations were performed to study the absorption processes of FSD and the Sum-Over-States (SOS) model was used to describe the 2PA process. A semi-classical method for spectrum simulations was employed to simulate the 1PA and 2PA cross-section spectra of FSD in water. For comparison purposes, in the case of the 2PA process two approaches, the "full expression" and "resonant expression" methods, were employed to simulate the nonlinear spectrum. The last method assumes resonant conditions and on the computation point of view it represents an interesting option to study the 2PA process. The INDO/CI calculations give a satisfactory description of the 1PA spectrum of FSD and properly describe the unusual blue-shift of its first π→π(*) transition in water. In the case of 2PA, the introduction of doubly excited configuration interactions (INDO/CISD) has proven to be essential for an appropriate description of the process at the higher energy spectral region. It was observed that the solvent effects do not drastically change the cross-sections of both processes. The simulated 2PA cross-section spectrum provided by the "full expression" method presents a better

  7. Pressure-dependent water absorption cross sections for exoplanets and other atmospheres

    NASA Astrophysics Data System (ADS)

    Barton, Emma J.; Hill, C.; Yurchenko, Sergei N.; Tennyson, Jonathan; Dudaryonok, Anna S.; Lavrentieva, Nina N.

    2017-01-01

    Many atmospheres (cool stars, brown dwarfs, giant planets, extrasolar planets) are predominately composed of molecular hydrogen and helium. H216O is one of the best measured molecules in extrasolar planetary atmospheres to date and a major compound in the atmospheres of brown-dwarfs and oxygen-rich cool stars, yet the scope of experimental and theoretical studies on the pressure broadening of water vapour lines by collision with hydrogen and helium remains limited. Theoretical H2- and He-broadening parameters of water vapour lines (rotational quantum number J up to 50) are obtained for temperatures in the range 300-2000 K. Two approaches for calculation of line widths were used: (i) the averaged energy difference method and (ii) the empirical expression for J ‧ J ″ -dependence. Voigt profiles based on these widths and the BT2 line list are used to generate high resolution (Δ ν ˜ = 0.01cm-1) pressure broadened cross sections for a fixed range of temperatures and pressures between 300 and 2000 K and 0.001-10 bar. An interpolation procedure which can be used to determine cross sections at intermediate temperature and pressure is described. Pressure broadening parameters and cross sections are presented in new ExoMol format.

  8. Understanding the two-photon absorption spectrum of PE2 platinum acetylide complex.

    PubMed

    Vivas, Marcelo G; De Boni, Leonardo; Cooper, Thomas M; Mendonca, Cleber R

    2014-07-31

    Herein, we report on the two-absorption cross-section spectrum of trans-Pt(PBu3)2 (C≡C-C6H4-C≡C-C6H5)2 (PE2) platinum acetylide complex employing the femtosecond wavelength-tunable Z-scan technique. The PE2 complex can be visualized as two branches containing two phenylacetylene units, each one linked by a platinum center, completely transparent in the visible region. Because of this structure, large delocalization of π-electrons allied to the strong intramolecular interaction between the branches is expected. The 2PA absorption spectrum was measured using the femtosecond wavelength-tunable Z-scan technique with low repetition rate (1 kHz), in order to obtain the 2PA spectrum without excited-state contributions. Our results reveal that PE2 in dichloromethane solution presents two 2PA allowed bands located at 570 and 710 nm, with cross section of about 320 and 45 GM, respectively. The first one is related to the strong intramolecular interaction between the molecule's branches due to the presence of platinum atom, while the second one is associated with the breaking of symmetry of the chromophore in solution due, most probably to a large twisting angle of the ligand's phenyl rings relative to the Pt core.

  9. Evaluation of the use of five laboratory-determined ozone absorption cross sections in Brewer and Dobson retrieval algorithms

    NASA Astrophysics Data System (ADS)

    Redondas, A.; Evans, R.; Stuebi, R.; Köhler, U.; Weber, M.

    2014-02-01

    The primary ground-based instruments used to report total column ozone (TOC) are Brewer and Dobson spectrophotometers in separate networks. These instruments make measurements of the UV irradiances, and through a well-defined process, a TOC value is produced. Inherent to the algorithm is the use of a laboratory-determined cross-section data set. We used five ozone cross-section data sets: three data sets that are based on measurements of Bass and Paur; one derived from Daumont, Brion and Malicet (DBM); and a new set determined by Institute of Experimental Physics (IUP), University of Bremen. The three Bass and Paur (1985) sets are as follows: quadratic temperature coefficients from the IGACO (a glossary is provided in Appendix A) web page (IGQ4), the Brewer network operational calibration set (BOp), and the set used by Bernhard et al. (2005) in the reanalysis of the Dobson absorption coefficient values (B05). The ozone absorption coefficients for Brewer and Dobson instruments are then calculated using the normal Brewer operative method, which is essentially the same as that used for Dobson instruments. Considering the standard TOC algorithm for the Brewer instruments and comparing to the Brewer standard operational calibration data set, using the slit functions for the individual instruments, we find the IUP data set changes the calculated TOC by -0.5%, the DBM data set changes the calculated TOC by -3.2%, and the IGQ4 data set at -45 °C changes the calculated TOC by +1.3%. Considering the standard algorithm for the Dobson instruments, and comparing to results using the official 1992 ozone absorption coefficients values and the single set of slit functions defined for all Dobson instruments, the calculated TOC changes by +1%, with little variation depending on which data set is used. We applied the changes to the European Dobson and Brewer reference instruments during the Izaña 2012 Absolute Calibration Campaign. With the application of a common Langley

  10. Apparent PS II absorption cross-section and estimation of mean PAR in optically thin and dense suspensions of Chlorella.

    PubMed

    Klughammer, Christof; Schreiber, Ulrich

    2015-01-01

    Theoretical prediction of effective mean PAR in optically dense samples is complicated by various optical effects, including light scattering and reflections. Direct information on the mean rate of photon absorption by PS II is provided by the kinetics of the fluorescence rise induced upon onset of strong actinic illumination (O-I1 rise). A recently introduced kinetic multi-color PAM fluorometer was applied to study the relationship between initial slope and cell density in the relatively simple model system of suspensions of Chlorella. Use of a curve fitting routine was made which was originally developed for assessment of the wavelength-dependent absorption cross-section of PS II, σ II(λ), in dilute suspensions. The model underlying analysis of the O-I1 rise kinetics is outlined and data on the relationship between fitted values of σ II(λ) and PAR in dilute samples are presented. With increasing cell density, lowering of apparent cross-section, <σ>(λ), with respect to σ II(λ), relates to a decrease of effective mean PAR, (λ), relative to incident PAR(λ). When ML and AL are applied in the same direction, the decline of <σ>(λ)/σ II(λ) with increasing optical density is less steep than that of the theoretically predicted (λ)/PAR(λ). It approaches a value of 0.5 when the same colors of ML and AL are used, in agreement with theory. These observations open the way for estimating mean PAR in optically dense samples via measurements of <σ>(λ)/σ II(λ)).

  11. Quantitative infrared absorption cross-sections of isoprene for atmospheric measurements

    DOE PAGES

    Brauer, C. S.; Blake, T. A.; Guenther, A. B.; ...

    2014-04-25

    Isoprene (C5H8, 2-methyl-1,3-butadiene) is a volatile organic compound (VOC) that is one of the primary contributors to annual global VOC emissions. Produced by vegetation as well as anthropogenic sources, the OH- and O3-initiated oxidations of isoprene are a major source of atmospheric oxygenated organics. Few quantitative infrared studies have been reported for isoprene, however, limiting the ability to quantify isoprene emissions via stand-off infrared or in situ detection. We thus report absorption coefficients and integrated band intensities for isoprene in the 600–6500 cm−1 region. The pressure-broadened (1 atmosphere N2) spectra were recorded at 278, 298 and 323 K in amore » 19.94 cm path length cell at 0.112 cm−1 resolution, using a Bruker 66v FTIR. Composite spectra are derived from a minimum of seven isoprene sample pressures at each temperature and the number densities are normalized to 296 K and 1 atmosphere.« less

  12. Pyrrolo[3,2-b]pyrroles-From Unprecedented Solvatofluorochromism to Two-Photon Absorption.

    PubMed

    Friese, Daniel H; Mikhaylov, Alexander; Krzeszewski, Maciej; Poronik, Yevgen M; Rebane, Aleksander; Ruud, Kenneth; Gryko, Daniel T

    2015-12-07

    A combined experimental and theoretical study of the two-photon absorption (2PA) properties of a series of quadrupolar molecules possessing a highly electron-rich heterocyclic core, pyrrolo[3,2-b]pyrrole, is presented. In agreement with quantum-chemical calculations, large 2PA cross-section values, σ2PA ≈10(2) -10(3)  GM (1 GM=10(50)  cm(4)  s photon(-1) ), are observed at wavelengths of 650-700 nm, which correspond to the two-photon allowed but one-photon forbidden transitions. The calculations also predict that increased planarity of this molecule through removal of two N-substituents leads to further increase in the σ2PA values. Surprisingly, the most quadrupolar pyrrolo[3,2-b]pyrrole derivative, containing two 4-nitrophenyl substituents at positions 2 and 5, demonstrates a very strong solvatofluorochromic effect, with a fluorescence quantum yield as high as 0.96 in cyclohexane, whereas the fluorescence vanishes in DMSO.

  13. New and improved infra-red absorption cross sections and ACE-FTS retrievals of carbon tetrachloride (CCl4)

    NASA Astrophysics Data System (ADS)

    Harrison, Jeremy J.; Boone, Christopher D.; Bernath, Peter F.

    2017-01-01

    Carbon tetrachloride (CCl4) is one of the species regulated by the Montreal Protocol on account of its ability to deplete stratospheric ozone. As such, the inconsistency between observations of its abundance and estimated sources and sinks is an important problem requiring urgent attention (Carpenter et al., 2014) [5]. Satellite remote-sensing has a role to play, particularly limb sounders which can provide vertical profiles into the stratosphere and therefore validate stratospheric loss rates in atmospheric models. This work is in two parts. The first describes new and improved high-resolution infra-red absorption cross sections of carbon tetrachloride/dry synthetic air over the spectral range 700-860 cm-1 for a range of temperatures and pressures (7.5-760 Torr and 208-296 K) appropriate for atmospheric conditions. This new cross-section dataset improves upon the one currently available in the HITRAN and GEISA databases. The second describes a new, preliminary ACE-FTS carbon tetrachloride retrieval that improves upon the v3.0/v3.5 data products, which are biased high by up to 20-30% relative to ground measurements. Making use of the new spectroscopic data, this retrieval also improves the microwindow selection, contains additional interfering species, and utilises a new instrumental lineshape; it will form the basis for the upcoming v4.0 CCl4 data product.

  14. Benchmarking two-photon absorption cross sections: performance of CC2 and CAM-B3LYP.

    PubMed

    Beerepoot, Maarten T P; Friese, Daniel H; List, Nanna H; Kongsted, Jacob; Ruud, Kenneth

    2015-07-15

    We investigate the performance of CC2 and TDDFT/CAM-B3LYP for the calculation of two-photon absorption (TPA) strengths and cross sections and contrast our results to a recent coupled cluster equation-of-motion (EOM-EE-CCSD) benchmark study [K. D. Nanda and A. I. Krylov, J. Chem. Phys., 2015, 142, 064118]. In particular, we investigate whether CC2 TPA strengths are significantly overestimated compared to higher-level coupled-cluster calculations for fluorescent protein chromophores. Our conclusion is that CC2 TPA strengths are only slightly overestimated compared to the reference EOM-EE-CCSD results and that previously published overestimated cross sections are a result of inconsistencies in the conversion of the TPA strengths to macroscopic units. TDDFT/CAM-B3LYP TPA strengths, on the other hand, are found to be 1.5 to 3 times smaller than the coupled-cluster reference for the molecular systems considered. The unsatisfactory performance of TDDFT/CAM-B3LYP can be linked to an underestimation of excited-state dipole moments predicted by TDDFT/CAM-B3LYP.

  15. Estimation of thermal neutron absorption cross-section from K, U and Th concentrations for Miocene rocks from the Carpathian Piedmont in Poland using artificial neural networks.

    PubMed

    Loskiewicz, J; Swakoń, J; Kulczykowska, K

    2000-06-01

    The radiometric K, U and Th concentrations and neutron absorption cross-section sigma a of rock samples obtained from coring are analysed. The cores are from wellbores located in the Sucha-Jordanów region (Carpathian Mountains) and from gas producing Miocene formations in the Carpathian foothills. Correlation coefficients between the neutron absorption cross-section (sigma a) and K, U and Th concentrations are presented. Neural network representation of the function sigma a = f(K, U, Th) obtained for a region can later be used for sigma a estimation from spectrometric probe results in uncored wells.

  16. o-nitrobenzyl photolabile protecting groups with red-shifted absorption: syntheses and uncaging cross-sections for one- and two-photon excitation.

    PubMed

    Aujard, Isabelle; Benbrahim, Chouaha; Gouget, Marine; Ruel, Odile; Baudin, Jean-Bernard; Neveu, Pierre; Jullien, Ludovic

    2006-09-06

    We evaluated the o-nitrobenzyl platform for designing photolabile protecting groups with red-shifted absorption that could be photolyzed upon one- and two-photon excitation. Several synthetic pathways to build different conjugated o-nitrobenzyl backbones, as well as to vary the benzylic position, are reported. Relative to the reference 4,5-dimethoxy-2-nitrobenzyl group, several o-nitrobenzyl derivatives exhibit a large and red-shifted one-photon absorption within the near-UV range. Uncaging after one-photon excitation was studied by measuring UV-visible absorption and steady-state fluorescence emission on model caged ethers and esters. In the whole series investigated, the caged substrates were released cleanly upon photolysis. Quantum yields of uncaging after one-photon absorption lie within the 0.1-1 % range. We observed that these drop as the maximum wavelength absorption of the o-nitrobenzyl protecting group is increased. A new method based on fluorescence correlation spectroscopy (FCS) after two-photon excitation was used to measure the action uncaging cross section for two-photon excitation. The series of o-nitrobenzyl caged fluorescent coumarins investigated exhibit values within the 0.1-0.01 Goeppert-Mayer (GM) range. Such results are in line with the low quantum yields of uncaging associated with cross-sections of 1-50 GM for two-photon absorption. Although the cross-sections for one- and two-photon absorption of o-nitrobenzyl photolabile protecting groups can be readily improved, we emphasize the difficulty in enlarging the corresponding action uncaging cross-sections in view of the observed trend of their quantum yield of uncaging.

  17. Classical Calculations of Scattering Signatures from a Gravitational Singularity or the Scattering and Absorption Cross-Sections of a Black Hole

    NASA Astrophysics Data System (ADS)

    Difilippo, Felix C.

    2012-09-01

    Within the context of general relativity theory we calculate, analytically, scattering signatures around a gravitational singularity: angular and time distributions of scattered massive objects and photons and the time and space modulation of Doppler effects. Additionally, the scattering and absorption cross sections for the gravitational interactions are calculated. The results of numerical simulations of the trajectories are compared with the analytical results.

  18. Large two-photon absorption cross sections of hemiporphyrazines in the excited state: the multiphoton absorption process of hemiporphyrazines with different central metals.

    PubMed

    Dini, Danilo; Calvete, Mario J F; Hanack, Michael; Amendola, Vincenzo; Meneghetti, Moreno

    2008-09-17

    A series of five hemiporphyrazines (Hps) with different coordinating central atoms (H2, GeCl2, InCl, Pt, Pb), and the acyclic derivative 1,3-bis-(6'-amino-4'-butoxy-2'-pyridylimino)-1,3-dihydroisoindoline have been synthesized and their multiphoton absorption properties examined at the second harmonic frequency of the Nd:YAG laser in the nanosecond time regime. Metal-free and platinum Hps display saturation of optical transmittance within incident fluence values of 6 J cm(-2). Comparison with other similar molecular structures like phthalocyanines and related molecules shows that Hps are strong nonlinear absorbers. The experimental curves of nonlinear transmission at 532 nm have been fitted by means of a three-level model with the occurrence of simultaneous two-photon absorption from an excited state. In the sole case of the InCl complex we found that a five-level model is needed because of the participation of triplet states. Contrary to phthalocyanines, naphthalocyanines, and porphyrins, a heavy central atom does not improve the nonlinear absorption properties since a different excited states dynamic is involved. The large nonlinear absorption of Hps combined with the very small absorption in the visible spectral range makes these molecules a very interesting class of molecules for nonlinear optical applications.

  19. Physical Absorption of Green House Gases in Amines: The Influence of Functionality, Structure, and Cross-Interactions.

    PubMed

    Orozco, Gustavo A; Lachet, Véronique; Mackie, Allan D

    2016-12-29

    Monte Carlo simulations were performed in the isothermal-isobaric ensemble (NPT) to calculate the Henry constants of methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2) in pure H2O, amines, and alkanolamines using the classical Lorentz-Berthelot combining rules (L-B). The Henry constants of N2O and CO2 in water are highly overestimated and motivated us to propose a new set of unlike interactions. Contrarily, the Henry constant of N2O in MEA is underestimated by around 40%, and again, a new reoptimized cross unlike parameter is able to reproduce the constant to within 10%. An analysis is given of the relationship between the physical absorption of these gases and the chemical structure or functionality of 12 molecules including amines and alkanolamines using the anisotropic united atom intermolecular potential (AUA4). Finally, the solubility of N2O in an aqueous solution of monoethanolamine (MEA) at 30% (wt) was also studied. A Henry constant within 7% of the experimental value was found by using the reoptimized parameters along with L-B to account for the MEA + H2O unlike interactions. This very good agreement without additional adjustments for the MEA + H2O system may be attributed to the good excess properties predictions found in previous works for the binary mixture (MEA + H2O). However, further work, including additional alkanolamines in aqueous solutions at several concentrations, is required to verify this particular point.

  20. Quantification of Brown Carbon Mass Absorption Cross Section from Sources through the Application of Physical and Mathematical Segregation of Black Carbon

    NASA Astrophysics Data System (ADS)

    Olson, M.; Van Rooy, P.; Dietenberger, M.; Short, K.; Zhan, Y.; Schauer, J. J.

    2015-12-01

    Quantification of the black carbon (BC) and brown carbon (BrC) components of source emissions is critical to understanding the impact combustion aerosols have on atmospheric light absorption. Multiple-wavelength absorption of particulate matter emissions was measured from combustion of wood, agricultural biomass, coals, leaf litter, and petroleum distillates in controlled combustion settings. Aethalometer corrected BC absorption was segregated mathematically from the total light extinction to estimate the BrC absorption from individual sources. Results were compared to elemental carbon (EC)/organic carbon (OC) concentrations to determine composition's impact on light absorption. The bulk carbonaceous aerosol and BrC Mass absorption cross section (MAC) were variable across source types and light wavelengths. Sources such as incense and peat emissions showed ultraviolet wavelength (370nm) BrC absorption over 175 and 80 times (respectively) the BC absorption but only 21 and 11 times (respectively) at 520nm wavelength. The bulk EC MACEC, λ (average at 520nm=9.0±3.7 m2 g-1; with OC fraction <0.85 = ~7.5 m2 g-1) and the BrC OC mass absorption cross sections (MACBrC,OC,λ) were calculated; at 370 nm ultraviolet wavelengths; the MACBrC,OC,λ ranged from 0.8 m2 g-1 to 2.29 m2 g-1 (lowest peat, highest kerosene), while at 520nm wavelength MACBrC,OC,λ ranged from 0.07 m2 g-1 to 0.37 m2 g-1 (lowest peat, highest kerosene/incense mixture). Samples from the same combustions sources were water and organic solvent extracted, filtered to physically remove BC, and the extracts were re-aerosolized in a controlled suspension chamber. The MACBrC,OC,λ derived from the re-suspended OC were compared to the mathematically derived MACBrC,OC,λ and were shown to have similar absorption spectra, however variability between the methods were observed, likely due to variations in particle size distributions, particle mixing state, and uncertainty associated with the OC quantification. The

  1. Photonuclear absorption cross sections

    NASA Technical Reports Server (NTRS)

    Norbury, John W.

    1989-01-01

    Neutron multiplicity in photonuclear reactions; invariance of classical electromagnetism; momentum transfer models in ion collisions; cosmic ray electromagnetic interactions; quadrupole excitations in nucleus-nucleus collisons and Y-89 interactions with relativistic nuclei; and the Weizsacker-Williams theory for nucleon emission via electromagnetic excitations in nucleus-nucleus collisions are discussed.

  2. Dipole Polarizabilities and Absorption Cross Sections of Two-Particle Nanoclusters of Conductive Homogeneous and Layered Particles with the Degenerate Electron Gas

    NASA Astrophysics Data System (ADS)

    Kucherenko, M. G.; Nalbandyan, V. M.

    2017-01-01

    Frequency dependences of the dipole polarizabilities of clusters consisting of two solid conducting spherical nanoparticles and double-layer metal nanoparticles are investigated versus the geometrical parameters of the system with taking into account the degeneracy of electron gas of its metallic components. It is established that the spectra of the dynamic polarizabilities and absorption cross-sections of clusters have a complex multiresonant structure and strong dependence on the configuration parameters of the cluster, the degree of degeneracy of the metal, and kinetic characteristics of its electron gas. Spectral transformations of the absorption cross-sections of nanoclusters are illustrated under variation of the radii of particles or theirs nuclei, characteristic lengths of the Thomas-Fermi screening, and frequency of electron collisions. The anisotropic nature of absorption of electromagnetic field energy by a cluster is established: it is shown that the value of the absorption cross section depends on the direction of the electric field strength vector relative to the axis of the cluster.

  3. Effect of the concentration of organic dyes on their surface plasmon enhanced two-photon absorption cross section using activated Au nanoparticles

    NASA Astrophysics Data System (ADS)

    Cohanoschi, Ion; Yao, Sheng; Belfield, Kevin D.; Hernández, Florencio E.

    2007-04-01

    In this article we present the study of the surface plasmon enhanced two-photon absorption of a hydrophilic stilbene derivative (trans-4,4'-diaminostilbene) in aqueous solution at different concentrations. The observed exponential growth of the effective two-photon absorption cross section [σ2'(Au)] is attributed to the electric-field augmentation via surface plasmon resonance between nanoparticles, i.e., hot spots, and the molecular density on Au nanospheres. An unprecedented σ2'(Au)=550 000 GM has been measured. This result opens a new universe of applications in multiphoton imaging, photodynamic therapy, telecommunications, optical limiting, and multidimensional data storage using hybrid systems.

  4. Pressure transfer function and absorption cross section from the diffuse field to the human infant ear canal.

    PubMed

    Keefe, D H; Bulen, J C; Campbell, S L; Burns, E M

    1994-01-01

    The diffuse-field pressure transfer function from a reverberant field to the ear canal of human infants, ages 1, 3, 6, 12, and 24 months, has been measured from 125-10700 Hz. The source was a loudspeaker using pink noise, and the diffuse-field pressure and the ear-canal pressure were simultaneously measured using a spatial averaging technique in a reverberant room. The results in most subjects show a two-peak structure in the 2-6-kHz range, corresponding to the ear-canal and concha resonances. The ear-canal resonance frequency decreases from 4.4 kHz at age 1 month to 2.9 kHz at age 24 months. The concha resonance frequency decreases from 5.5 kHz at age 1 month to 4.5 kHz at age 24 months. Below 2 kHz, the diffuse-field transfer function shows effects due to the torsos of the infant and parent, and varies with how the infant is held. Comparisons are reported of the diffuse-field absorption cross section for infants relative to adults. This quantity is a measure of power absorbed by the middle ear from a diffuse sound field, and large differences are observed in infants relative to adults. The radiation efficiencies of the infant and the adult ear are small at low frequencies, near unity at midfrequencies, and decrease at higher frequencies. The process of ear-canal development is not yet complete at age 24 months. The results have implications for experiments on hearing in infants.

  5. High resolution absorption cross-sections and band oscillator strengths of the Schumann-Runge bands of oxygen at 79 K

    NASA Technical Reports Server (NTRS)

    Yoshino, K.; Freeman, D. E.; Esmond, J. R.; Parkinson, W. H.

    1987-01-01

    Cross sections of O2 at 79 K have been obtained from photoabsorption measurements at various pressures throughout the wavelength region 179.3-198.0 nm with a 6.65-m photoelectric scanning spectrometer equipped with a 2400-lines/mm grating and having an instrumental width (FWHM) of 0.0013 nm. The measured absorption cross sections of the Schumann-Runge bands (12,0) through (2,0) are independent of the instrumental width. The measured cross-sections are presented graphically here and are available at wavenumber intervals of about 0.1/cm as numerical compilations stored on magnetic tape from the National Space Science Data Center, NASA/Goddard. Band oscillator strengths of these bands have been determined by direct numerical integration of the measured cross sections.

  6. High resolution absolute absorption cross sections of the B ̃(1)A'-X ̃(1)A' transition of the CH2OO biradical.

    PubMed

    Foreman, Elizabeth S; Kapnas, Kara M; Jou, YiTien; Kalinowski, Jarosław; Feng, David; Gerber, R Benny; Murray, Craig

    2015-12-28

    Carbonyl oxides, or Criegee intermediates, are formed from the gas phase ozonolysis of alkenes and play a pivotal role in night-time and urban area atmospheric chemistry. Significant discrepancies exist among measurements of the strong B ̃(1)A'-X ̃(1)A' electronic transition of the simplest Criegee intermediate, CH2OO in the visible/near-UV. We report room temperature spectra of the B ̃(1)A'-X ̃(1)A' electronic absorption band of CH2OO acquired at higher resolution using both single-pass broadband absorption and cavity ring-down spectroscopy. The new absorption spectra confirm the vibrational structure on the red edge of the band that is absent from ionization depletion measurements. The absolute absorption cross sections over the 362-470 nm range are in good agreement with those reported by Ting et al. Broadband absorption spectra recorded over the temperature range of 276-357 K were identical within their mutual uncertainties, confirming that the vibrational structure is not due to hot bands.

  7. Reduced mass absorption cross section of black carbon under an extremely polluted condition in southern suburb of Beijing, China

    NASA Astrophysics Data System (ADS)

    Wang, J.; Wang, S.; Hua, Y.; Jiang, J.; Zhao, B.; Xing, J.; Jiang, S.; Cai, R.; Hao, J.

    2015-12-01

    Black carbon (BC), as one of the most important climate-warming agent, has been the focus of extensive studies in recent years. Mass absorption cross section (MAC) is a key parameter to assess the radiative forcing by linking the mass concentration with the radiation effect. In this study, we conducted a two-month field campaign in Beijing, the capital city of China, in a October and November, a period that severe PM2.5 pollution occurred. PM2.5 offline samples were collected daily onto quartz fiber filters by a Partisol 2300 Speciation Sampler. Size-segregated aerosol samples of the size ranged from 0.056 - 10 µm with 11 bins were collected onto quartz fiber filters by a cascade impactor developed by National Chiao Tung University (NCTU). A DRI Model 2001 thermal/optical carbon analyzer were used to analyze the samples. The MAC of BC is measured by a thermal-optical carbon analyzer. In contrast to previous studies, we found that after "shadow effect" has been corrected, the MAC is reduced from 14 m2/g to 5 m2/g with the increase of BC concentrations. There was no significant correlation between MAC with secondary inorganic aerosols. Such unexpected reduction in MAC of BC is possibly associated with the microphysical property of BC modulated under serious pollution condition. The study of size-segregated species concentrations shows that the size distribution of BC is unimodal, with the peak around 0.56-1.8 µm. The results also show the proportion of BC larger than 0.56 µm is significant increased. Additionally, "soot superaggregate", as distinct from conventional sub-micron aggregates, was found in the bins of BC with size ranged from 1 to1.8 µm. Such high carbon aerosol proportion and large BC size distribution suggests that emissions from residential biomass burning is dominant during this episode. This study suggests that the optical property for BC from different emission sectors should be considered in the estimation of radiative forcing.

  8. UV Absorption Cross Sections of Nitrous Oxide (N2O) and Carbon Tetrachloride (CCl4) Between 210 and 350 K and the Atmospheric Implications

    NASA Technical Reports Server (NTRS)

    Carlon, Nabilah Rontu; Papanastasiou, Dimitrios K.; Fleming, Eric L.; Jackman, Charles H.; Newman, Paul A.; Burkholder, James B.

    2010-01-01

    Absorption cross sections of nitrous oxide (N2O) and carbon tetrachloride (CCl4) are reported at five atomic UV lines (184.95, 202.548, 206.200, 213.857, and 228.8 nm) at 27 temperatures in the range 210-350 K. In addition, UV absorption spectra of CCl4 are reported between 200-235 nm as a function of temperature (225-350 K). The results from this work are critically compared with results from earlier studies. For N2O, the present results are in good agreement with the current JPL recommendation enabling a reduction in the estimated uncertainty in the N2O atmospheric photolysis rate. For CCl4, the present cross section results are systematically greater than the current recommendation at the reduced temperatures most relevant to stratospheric photolysis. The new cross sections result in a 5-7% increase in the modeled CCl4 photolysis loss, and a slight decrease in the stratospheric lifetime, from 51 to 50 years, for present day conditions. The corresponding changes in modeled inorganic chlorine and ozone in the stratosphere are quite small. A CCl4 cross section parameterization for use in 37 atmospheric model calculations is presented.

  9. Absorption cross sections for HF laser lines due to traces of CO/sub 2/, N/sub 2/O, and CH/sub 4/ in air

    SciTech Connect

    Agroskin, V.Ya.; Vasil'ev, G.K.; Gur'ev, V.I.; Tatarinova, E.E.

    1986-12-01

    The emission from an HF (DF) laser is spread over a large number of vibrational-rotational lines in the range 2.7-4.2 ..mu..m, which contains absorption bands of virtually all substances of interesting quantitative gas analysis, and in particular, detecting atmospheric pollutants, determining discharges from industrial plants, locating deposits of certain minerals, forecasting volcanic activity, and so on. Pulsed chemical HF (DF) lasers can be based on the chain reaction of fluorine with hydrogen (deuterium), which is promising for these purposes because the number of lines is large by comparison with any other type of laser (about 100 lines). These lasers also have high efficiency in converting the pumping energy to radiation and high beam power with relatively small dimensions and the same laser cell can be used to obtain the emission from carbon dioxide in the range 9.6-10.6 ..mu..m by energy transfer from DF to carbon dioxide. It is necessary to know the absorption characteristics of the substances at the lines of the HF (DF) laser. In this paper, the authors report measured cross sections for carbon dioxide, nitrogen oxide, and carbon hydrogenate, in the form of minor impurities in the air (about 1-10%) for various lines from an HF laser. The authors compare the data with published values, while the available spectroscopic characteristics are used in theoretical calculations of the absorption cross section and compared with the experiment.

  10. Broadband transient absorption spectroscopy with 1- and 2-photon excitations: Relaxation paths and cross sections of a triphenylamine dye in solution

    SciTech Connect

    Moreno, J.; Dobryakov, A. L.; Hecht, S. E-mail: skovale@chemie.hu-berlin.de; Kovalenko, S. A. E-mail: skovale@chemie.hu-berlin.de; Ioffe, I. N.; Granovsky, A. A.

    2015-07-14

    1-photon (382 nm) and 2-photon (752 nm) excitations to the S{sub 1} state are applied to record and compare transient absorption spectra of a push-pull triphenylamine (TrP) dye in solution. After 1-photon excitation, ultrafast vibrational and structural molecular relaxations are detected on a 0.1 ps time scale in nonpolar hexane, while in polar acetonitrile, the spectral evolution is dominated by dipolar solvation. Upon 2-photon excitation, transient spectra in hexane reveal an unexpected growth of stimulated emission (SE) and excited-state absorption (ESA) bands. The behavior is explained by strong population transfer S{sub 1} → S{sub n} due to resonant absorption of a third pump photon. Subsequent S{sub n} → S{sub 1} internal conversion (with τ{sub 1} = 1 ps) prepares a very hot S{sub 1} state which cools down with τ{sub 2} = 13 ps. The pump pulse energy dependence proves the 2-photon origin of the bleach signal. At the same time, SE and ESA are strongly affected by higher-order pump absorptions that should be taken into account in nonlinear fluorescence applications. The 2-photon excitation cross sections σ{sup (2)} = 32 ⋅ 10{sup −50} cm{sup 4} s at 752 nm are evaluated from the bleach signal.

  11. Broadband transient absorption spectroscopy with 1- and 2-photon excitations: Relaxation paths and cross sections of a triphenylamine dye in solution.

    PubMed

    Moreno, J; Dobryakov, A L; Ioffe, I N; Granovsky, A A; Hecht, S; Kovalenko, S A

    2015-07-14

    1-photon (382 nm) and 2-photon (752 nm) excitations to the S1 state are applied to record and compare transient absorption spectra of a push-pull triphenylamine (TrP) dye in solution. After 1-photon excitation, ultrafast vibrational and structural molecular relaxations are detected on a 0.1 ps time scale in nonpolar hexane, while in polar acetonitrile, the spectral evolution is dominated by dipolar solvation. Upon 2-photon excitation, transient spectra in hexane reveal an unexpected growth of stimulated emission (SE) and excited-state absorption (ESA) bands. The behavior is explained by strong population transfer S1 → Sn due to resonant absorption of a third pump photon. Subsequent Sn → S1 internal conversion (with τ1 = 1 ps) prepares a very hot S1 state which cools down with τ2 = 13 ps. The pump pulse energy dependence proves the 2-photon origin of the bleach signal. At the same time, SE and ESA are strongly affected by higher-order pump absorptions that should be taken into account in nonlinear fluorescence applications. The 2-photon excitation cross sections σ(2) = 32 ⋅ 10(-50) cm(4) s at 752 nm are evaluated from the bleach signal.

  12. Chromophores and Materials for Temporal and Frequency Agile Non-Linear Absorption

    DTIC Science & Technology

    2014-05-31

    is related to the proposed new research, we explored the effects of stereochemistry on the photophysics, 2PA absorption and nanosecond NLA...600 nm. This result reveals how subtle aspects such as stereochemistry (and symmetry) can influence the 2PA and the NLA response to longer pulses

  13. A Series of Imidazole Derivatives: Synthesis, Two-Photon Absorption, and Application for Bioimaging

    PubMed Central

    Zhu, Yingzhong; Xiao, Lufei; Zhao, Meng; Zhou, Jiazheng; Zhang, Qiong; Wang, Hui; Li, Shengli; Zhou, Hongping; Wu, Jieying; Tian, Yupeng

    2015-01-01

    A new series of D-π-A type imidazole derivatives have been synthesized and characterized. Two corresponding imidazolium salts (iodine and hexafluorophosphate) were prepared from the imidazole compound. Their electron-withdrawing ability can be largely tunable by salt formation reaction or ion exchange. UV-vis absorption and single-photon fluorescence spectra have been systematically investigated in different solvents. The two-photon cross sections (δ2PA) of the imidazole derivatives are measured by two-photon excited fluorescence (2PEF) method. Compared with those of T-1 (107 GM) and T-3 (96 GM), T-2 (imidazolium iodine salt) has a large two-photon absorption (2PA) cross section value of 276 GM. Furthermore, the cytotoxicity and applications in bioimaging for the imidazole derivatives were carried out. The results showed that T-1 can be used as a lysosomal tracker with high stability and water solubility within pHs of 4–6, while T-2 and T-3 can be used as probes for cell cytoplasm. PMID:26579544

  14. Black carbon over Mexico: The effect of atmospheric transport on mixing state, mass absorption cross-section, and BC/CO ratios

    SciTech Connect

    Subramanian, R.; Kok, G. L.; Baumgardner, Darrel; Clarke, A. D.; Shinozuka, Y.; Campos, Teresa; Heizer, CG; Stephens, Britton; de Foy, B.; Voss, Paul B.; Zaveri, Rahul A.

    2010-01-13

    A single particle soot photometer (SP2) was operated on the NCAR C-130 during the MIRAGE campaign (part of MILAGRO), sampling black carbon (BC) over Mexico. The highest BC concentrations were measured over Mexico City (sometimes as much as 2 Fg/m34 ) and over hill fires to the south of the city. The age of plumes outside of Mexico City was determined using a combination of HYSPLIT trajectories, WRF-FLEXPART modeling and CMET balloon tracks. As expected, older, diluted air masses had lower BC concentrations. A comparison of carbon monoxide (CO) and BC suggests a CO background of around 65 ppbv, and a backgroundcorrected BC/COnet ratio of 2.89±0.89 (ng/m39 -STP)/ppbv (average ± standard deviation). This ratio is similar for fresh emissions over Mexico City, as well as for aged airmasses. Comparison of light absorption measured with a particle soot absorption photometer (PSAP) and the SP2 BC suggests a BC mass-normalized absorption cross-section (MAC) of 10.9±2.1 m212 /g at 660 nm (or 13.1 m213 /g @ 550 nm, assuming MAC is inversely dependent on wavelength). This appears independent of aging and similar to the expected absorption cross-section for aged BC, but values, particularly in fresh emissions, could be biased high due to instrument artifacts. SP2-derived BC coating indicators show a prominent thinly-coated BC mode over the Mexico City Metropolitan Area (MCMA), while older air masses show both thinly-coated and thickly-coated BC. Some 2-day-old plumes do not show a prominent thickly-coated BC mode, possibly due to preferential wet scavenging of the likely-hydrophilic thickly-coated BC.

  15. Absorption Cross Sections of 2-Nitrophenol in the 295-400 nm Region and Photolysis of 2-Nitrophenol at 308 and 351 nm.

    PubMed

    Sangwan, Manuvesh; Zhu, Lei

    2016-12-22

    2-Nitrophenol is an important component of "brown carbon" in the atmosphere. Photolysis is its dominant gas phase removal process. We have determined the gas phase absorption cross sections of 2-nitrophenol in the 295-400 nm region by using cavity ring-down spectroscopy. 2-Nitrophenol exhibits a broad absorption band over the wavelength region studied, with the peak absorption located at 345 nm. Absorption cross section values range between (2.86 ± 0.18) × 10(-18) and (2.63 ± 0.31) × 10(-20) cm(2)/molecule over the 295-400 nm range. We have investigated the HONO, NO2, and OH formation channels following the gas phase photolysis of 2-nitrophenol at 308 and 351 nm. Direct NO2 formation was not observed. HONO and OH are direct products from 2-nitrophenol photolysis. The average OH quantum yields from the photolysis of 0.5, 1.0, and 2.0 mTorr of 2-nitrophenol are 0.69 ± 0.07 and 0.70 ± 0.07 at 308 and 351 nm. The average HONO quantum yields are 0.34 ± 0.09 and 0.39 ± 0.07 at 308 and 351 nm. The OH and HONO quantum yields are independent of nitrogen carrier gas pressure in the 20-600 Torr range. Oxidant formation rate constants from 2-nitrophenol photolysis have been calculated. Discussions have been made concerning the role of 2-nitrophenol gas phase photolysis in the formation of atmospheric oxidants in regions of high anthropogenic emissions.

  16. Black carbon over Mexico: the effect of atmospheric transport on mixing state, mass absorption cross-section, and BC/CO ratios

    NASA Astrophysics Data System (ADS)

    Subramanian, R.; Kok, G. L.; Baumgardner, D.; Clarke, A.; Shinozuka, Y.; Campos, T. L.; Heizer, C. G.; Stephens, B. B.; de Foy, B.; Voss, P. B.; Zaveri, R. A.

    2010-01-01

    A single particle soot photometer (SP2) was operated on the NCAR C-130 during the MIRAGE campaign (part of MILAGRO), sampling black carbon (BC) over Mexico. The highest BC concentrations were measured over Mexico City (sometimes as much as 2 μg/m3) and over hill-fires to the south of the city. The age of plumes outside of Mexico City was determined using a combination of HYSPLIT trajectories, WRF-FLEXPART modeling and CMET balloon tracks. As expected, older, diluted air masses had lower BC concentrations. A comparison of carbon monoxide (CO) and BC suggests a CO background of around 65 ppbv, and a background-corrected BC/COnet ratio of 2.89±0.89 (ng/m3-STP)/ppbv (average ± standard deviation). This ratio is similar for fresh emissions over Mexico City, as well as for aged airmasses. Comparison of light absorption measured with a particle soot absorption photometer (PSAP) and the SP2 BC suggests a BC mass-normalized absorption cross-section (MAC) of 10.9±2.1 m2/g at 660 nm (or 13.1 m2/g @ 550 nm, assuming MAC is inversely dependent on wavelength). This appears independent of aging and similar to the expected absorption cross-section for aged BC, but values, particularly in fresh emissions, could be biased high due to instrument artifacts. SP2-derived BC coating indicators show a prominent thinly-coated BC mode over the Mexico City Metropolitan Area (MCMA), while older air masses show both thinly-coated and thickly-coated BC. Some 2-day-old plumes do not show a prominent thickly-coated BC mode, possibly due to preferential wet scavenging of the likely-hydrophilic thickly-coated BC.

  17. Experimental determination of the absorption cross-section and molar extinction coefficient of CdSe and CdTe nanowires.

    PubMed

    Protasenko, Vladimir; Bacinello, Daniel; Kuno, Masaru

    2006-12-21

    Absorption cross-sections and corresponding molar extinction coefficients of solution-based CdSe and CdTe nanowires (NWs) are determined. Chemically grown semiconductor NWs are made via a recently developed solution-liquid-solid (SLS) synthesis, employing low melting Au/Bi bimetallic nanoparticle "catalysts" to induce one-dimensional (1D) growth. Resulting wires are highly crystalline and have diameters between 5 and 12 nm as well as lengths exceeding 10 microm. Narrow diameters, below twice the corresponding bulk exciton Bohr radius of each material, place CdSe and CdTe NWs within their respective intermediate to weak confinement regimes. Supporting this are solution linear absorption spectra of NW ensembles showing blue shifts relative to the bulk band gap as well as structure at higher energies. In the case of CdSe, the wires exhibit band edge emission as well as strong absorption/emission polarization anisotropies at the ensemble and single-wire levels. Analogous photocurrent polarization anisotropies have been measured in recently developed CdSe NW photodetectors. To further support fundamental NW optical/electrical studies as well as to promote their use in device applications, experimental absorption cross-sections are determined using correlated transmission electron microscopy, UV/visible extinction spectroscopy, and inductively coupled plasma atomic emission spectroscopy. Measured CdSe NW cross-sections for 1 microm long wires (diameters, 6-42 nm) range from 6.93 x 10(-13) to 3.91 x 10(-11) cm2 at the band edge (692-715 nm, 1.73-1.79 eV) and between 3.38 x 10(-12) and 5.50 x 10(-11) cm2 at 488 nm (2.54 eV). Similar values are obtained for 1 microm long CdTe NWs (diameters, 7.5-11.5 nm) ranging from 4.32 x 10(-13) to 5.10 x 10(-12) cm2 at the band edge (689-752 nm, 1.65-1.80 eV) and between 1.80 x 10(-12) and 1.99 x 10(-11) cm2 at 2.54 eV. These numbers compare well with previous theoretical estimates of CdSe/CdTe NW cross-sections far to the blue of the

  18. On the optimization of the isotopic neutron source method for measuring the thermal neutron absorption cross section: advantages and disadvantages of BF3 and 3He counters.

    PubMed

    Bolewski, A; Ciechanowski, M; Dydejczyk, A; Kreft, A

    2008-04-01

    The effect of the detector characteristics on the performance of an isotopic neutron source device for measuring thermal neutron absorption cross section (Sigma) has been examined by means of Monte Carlo simulations. Three specific experimental arrangements, alternately with BF(3) counters and (3)He counters of the same sizes, have been modelled using the MCNP-4C code. Results of Monte Carlo calculations show that devices with BF(3) counters are more sensitive to Sigma, but high-pressure (3)He counters offer faster assays.

  19. In-situ determination of macroscopic thermal neutron absorption cross-section of borehole model materials using the integrated flux method

    NASA Astrophysics Data System (ADS)

    Menn, Scott A.; Hall, Hugh E.

    1995-02-01

    The integrated thermal neutron flux method of determining the macroscopic thermal neutron absorption cross-section of samples consisting of approx. 400 kg of unconsolidated geologic material, saturated with fresh water, to be used in borehole models is reported. One advantage of this method is that bulk cross-section determinations are made relative to a single standard, with fresh (distilled) water being used as the standard in this work. The values of matrix Σ determined for unconsolidated sand, limestone, and dolomite for the particular samples measured fall within the range of previously reported measurements of similar type samples. The method was checked using 50,000 ppm NaCl for which a value of 39.1 ± 0.5 c.u. was determined.

  20. The 4He Total Photo-Absorption Cross Section With Two- Plus Three-Nucleon Interactions From Chiral Effective Field Theory

    SciTech Connect

    Quaglioni, S; Navratil, P

    2007-03-09

    The total photo-absorption cross section of {sup 4}He is evaluated microscopically using two- (NN) and three-nucleon (NNN) interactions based upon chiral effective field theory ({chi}EFT). The calculation is performed using the Lorentz integral transform method along with the ab initio no-core shell model approach. An important feature of the present study is the consistency of the NN and NNN interactions and also, through the Siegert theorem, of the two- and three-body current operators. This is due to the application of the {chi}EFT framework. The inclusion of the NNN interaction produces a suppression of the peak height and enhancement of the tail of the cross section. We compare to calculations obtained using other interactions and to representative experiments. The rather confused experimental situation in the giant resonance region prevents discrimination among different interaction models.

  1. Theoretical X-ray production cross sections at incident photon energies across L{sub i} (i=1-3) absorption edges of Br

    SciTech Connect

    Puri, Sanjiv

    2015-08-28

    The X-ray production (XRP) cross sections, σ{sub Lk} (k = l, η, α, β{sub 6}, β{sub 1}, β{sub 3}, β{sub 4}, β{sub 9,10}, γ{sub 1,5}, γ{sub 2,3}) have been evaluated at incident photon energies across the L{sub i}(i=1-3) absorption edge energies of {sub 35}Br using theoretical data sets of different physical parameters, namely, the L{sub i}(i=1-3) sub-shell the X-ray emission rates based on the Dirac-Fock (DF) model, the fluorescence and Coster Kronig yields based on the Dirac-Hartree-Slater (DHS) model, and two sets of the photoionisation cross sections based on the relativistic Hartree-Fock-Slater (RHFS) model and the Dirac-Fock (DF) model, in order to highlight the importance of electron exchange effects at photon energies in vicinity of absorption edge energies.

  2. The influenza A virus PB2, PA, NP, and M segments play a pivotal role during genome packaging.

    PubMed

    Gao, Qinshan; Chou, Yi-Ying; Doğanay, Sultan; Vafabakhsh, Reza; Ha, Taekjip; Palese, Peter

    2012-07-01

    The genomes of influenza A viruses consist of eight negative-strand RNA segments. Recent studies suggest that influenza viruses are able to specifically package their segmented genomes into the progeny virions. Segment-specific packaging signals of influenza virus RNAs (vRNAs) are located in the 5' and 3' noncoding regions, as well as in the terminal regions, of the open reading frames. How these packaging signals function during genome packaging remains unclear. Previously, we generated a 7-segmented virus in which the hemagglutinin (HA) and neuraminidase (NA) segments of the influenza A/Puerto Rico/8/34 virus were replaced by a chimeric influenza C virus hemagglutinin/esterase/fusion (HEF) segment carrying the HA packaging sequences. The robust growth of the HEF virus suggested that the NA segment is not required for the packaging of other segments. In this study, in order to determine the roles of the other seven segments during influenza A virus genome assembly, we continued to use this HEF virus as a tool and analyzed the effects of replacing the packaging sequences of other segments with those of the NA segment. Our results showed that deleting the packaging signals of the PB1, HA, or NS segment had no effect on the growth of the HEF virus, while growth was greatly impaired when the packaging sequence of the PB2, PA, nucleoprotein (NP), or matrix (M) segment was removed. These results indicate that the PB2, PA, NP, and M segments play a more important role than the remaining four vRNAs during the genome-packaging process.

  3. Determination of Two-Photon Absorption Cross-Section of Noble Gases for Calibration of Laser Spectroscopic Techniques

    SciTech Connect

    Rosa, M. I. de la; Perez, C.; Gruetzmacher, K.; Fuentes, L. M.

    2008-10-22

    The objective of our work is to apply two-photon polarization spectroscopy as a new calibration method for the determination of two-photon excitation cross-sections of noble gases, like Xe and Kr, which are commonly used for calibrations of MP-LIF techniques in other laboratories.

  4. Efficient photochromic transformation of a new fluorenyl diarylethene: one- and two-photon absorption spectroscopy.

    PubMed

    Luchita, Gheorghe; Bondar, Mykhailo V; Yao, Sheng; Mikhailov, Ivan A; Yanez, Ciceron O; Przhonska, Olga V; Masunov, Artem E; Belfield, Kevin D

    2011-09-01

    Efficient reversible phototransformation of a new diarylethene-fluorene derivative, 1,2-bis(5-(9,9-didecyl-7-nitro-9H-fluoren-2-yl)-2-methylthiophen-3-yl)cyclopent-1-ene (1), was demonstrated in organic media under low-intensity laser excitation. Linear photophysical characterization of 1 was performed at room temperature in solvents of different polarity and viscosity. Significantly, close to unity quantum yield for the cyclization reaction of 1 was shown in nonpolar solutions. The lifetimes of the excited states of the open (OF) and closed (CF) forms of 1 were measured by a femtosecond transient absorption technique, and corresponding values of ∼0.7 and ∼0.9 ps were shown in dichloromethane (DCM), respectively. Degenerate two-photon absorption (2PA) spectra of the OF and CF of 1 were obtained over a broad spectral range by the open aperture Z-scan method under 1 kHz femtosecond excitation. The values of 2PA cross sections of the OF in DCM (∼50-70 GM) were found to increase up to 1 order of magnitude (∼600 GM) after cyclization to the CF. The nature of cyclization and cylcoreversion processes were investigated by quantum chemistry with employment of DFT-based methods implemented in the Gaussian'09 program. The potential of 1 for application in optical data storage was shown using poly(methyl methacrylate)-doped films and two-photon fluorescence microscopy readout.

  5. Optimization of the steady neutron source technique for absorption cross section measurement by using an 124Sb-Be neutron source

    NASA Astrophysics Data System (ADS)

    Sun, Jing; Gardner, Robin P.

    2004-01-01

    An improved experimental approach has been developed to determine thermal neutron absorption cross sections. It uses an 124Sb-Be neutron source which has an average neutron energy of only about 12 keV. It can be moderated in either a water tank or a paraffin filled box and can be used for aqueous or powder samples. This new design is first optimized by MCNP simulation and then benchmarked and calibrated with experiments to verify the simulations and realize the predicted improved measurement sensitivity and reproducibility. The 124Sb-Be source device is from 1.35 to 1.71 times more sensitive than the previous method based on the use of a 252Cf source.

  6. Absorption Spectroscopy, Emissive Properties, and Ultrafast Intersystem Crossing Processes in Transition Metal Complexes: TD-DFT and Spin-Orbit Coupling.

    PubMed

    Daniel, Chantal

    2016-01-01

    Absorption spectroscopy, emissive properties, and ultrafast intersystem crossing processes in transition metal complexes are discussed in the light of recent developments in time-dependent density functional theory (TD-DFT), spin-orbit coupling (SOC) effects, and non-adiabatic excited states dynamics. Methodological highlights focus on spin-orbit and vibronic couplings and on the recent strategies available for simulating ultra-fast intersystem crossings (ISC).The role of SOC in the absorption spectroscopy of third-row transition metal complexes is illustrated by two cases studies, namely Ir(III) phenyl pyridine and Re(I) carbonyl bipyridine complexes.The problem of luminescence decay in third-row transition metal complexes handled by TD-DFT linear and quadratic response theories including SOC is exemplified by three studies: (1) the phosphorescence of Ir(III) complexes from the lowest triplet state; (2) the emissive properties of square planar Pt(II) complexes with bidentate and terdentate ligands characterized by low-lying metal-to-ligand-charge-transfer (MLCT) and metal-centered (MC) states; and (3) the ultra-fast luminescence decay of Re(I) carbonyl bipyridine halides via low-lying singlet and triplet charge transfer states delocalized over the bipyridine and the halide ligands.Ultrafast ISC occurring in spin crossover [Fe (bpy)3]2+, in [Ru (bpy)3]2+, and [Re (Br)(CO)3(bpy] complexes are deciphered thanks to recent developments based on various approaches, namely non-radiative rate theory within the Condon approximation, non-adiabatic surface hopping molecular dynamics, and quantum wave packet dynamics propagation.

  7. A Novel Algorithm Applied to Common Thermal-Optical Transmission Data for Determining Mass Absorption Cross Sections of Atmospheric Black Carbon: Applications to the Indian Outflow

    NASA Astrophysics Data System (ADS)

    Andersson, A.; Sheesley, R. J.; Kirillova, E.; Gustafsson, O.

    2010-12-01

    High wintertime concentrations of black carbon aerosols (BCA) over South Asia and the Northern Indian Ocean are thought to have a large impact on the regional climate. Direct absorption of sunlight by BCAs causes heating of the atmosphere and cooling at the surface. To quantify such effects it is important to characterize a number of different properties of the aerosols. Here we present a novel application of the thermal-optical (OCEC) instrument in which the laser beam is used to obtain optical information about the aerosols. In particular, the novel algorithm accounts for non-carbon contributions to the light extinction. Combining these light extinction coefficients with the simultaneously constrained Elemental Carbon (EC) concentrations, the Mass Absorption Cross Section (MAC) is computed. Samples were collected during a continuous 14-month campaign Dec 2008 - Mar 2009 at Sinaghad in Western India and on Hanimaadhoo, the Northernmost Island in the Maldives. This data set suggests that the MAC of the BCAs are variable, sometimes by a factor of 3 compared to the mean. This observation adds to the complexity of calculating the radiative forcing for BCAs, reinforcing previous observations that parameters such as aerosol mixing state and sources need to be taken into account.

  8. Effect of fiber orientation and cross section of composite tubes on their energy absorption ability in axial dynamic loading

    NASA Astrophysics Data System (ADS)

    Shokrieh, M. M.; Tozandehjani, H.; Omidi, M. J.

    2009-11-01

    The crushing behavior of composite tubes in axial impact loading is investigated. Tubes of circular and rectangular cross section are simulated using an LS-DYNA software. The effect of fiber orientation on the energy absorbed in laminated composite tubes is also studied. The results obtained show that rectangular tubes absorb less energy than circular ones, and their maximum crushing load is also lower. The composite tubes with a [+θ/ -θ] lay-up configuration absorb a minimum amount of energy at θ = 15°. The simulation results for a rectangular composite tube with a [+30/-30] lay-up configuration are compared with available experimental data. Cylindrical composite tubes fabricated from woven glass/polyester composites with different lay-ups were also tested using a drop-weight impact tester, and very good agreement between experimental and numerical results is achieved.

  9. Toward Improving Atmospheric Models and Ozone Projections: Laboratory UV Absorption Cross Sections and Equilibrium Constant of ClOOCl

    NASA Astrophysics Data System (ADS)

    Wilmouth, D. M.; Klobas, J. E.; Anderson, J. G.

    2015-12-01

    Thirty years have now passed since the discovery of the Antarctic ozone hole, and despite comprehensive international agreements being in place to phase out CFCs and halons, polar ozone losses generally remain severe. The relevant halogen compounds have very long atmospheric lifetimes, which ensures that seasonal polar ozone depletion will likely continue for decades to come. Changes in the climate system can further impact stratospheric ozone abundance through changes in the temperature and water vapor structure of the atmosphere and through the potential initiation of solar radiation management efforts. In many ways, the rate at which climate is changing must now be considered fast relative to the slow removal of halogens from the atmosphere. Photochemical models of Earth's atmosphere play a critical role in understanding and projecting ozone levels, but in order for these models to be accurate, they must be built on a foundation of accurate laboratory data. ClOOCl is the centerpiece of the catalytic cycle that accounts for more than 50% of the chlorine-catalyzed ozone loss in the Arctic and Antarctic stratosphere every spring, and so uncertainties in the ultraviolet cross sections of ClOOCl are particularly important. Additionally, the equilibrium constant of the dimerization reaction of ClO merits further study, as there are important discrepancies between in situ measurements and lab-based models, and the JPL-11 recommended equilibrium constant includes high error bars at atmospherically relevant temperatures (~75% at 200 K). Here we analyze available data for the ClOOCl ultraviolet cross sections and equilibrium constant and present new laboratory spectroscopic results.

  10. Filter-based measurements of UV-vis mass absorption cross sections of organic carbon aerosol from residential biomass combustion: Preliminary findings and sources of uncertainty

    NASA Astrophysics Data System (ADS)

    Pandey, Apoorva; Pervez, Shamsh; Chakrabarty, Rajan K.

    2016-10-01

    Combustion of solid biomass fuels is a major source of household energy in developing nations. Black (BC) and organic carbon (OC) aerosols are the major PM2.5 (particulate matter with aerodynamic diameter smaller than 2.5 μm) pollutants co-emitted during burning of these fuels. While the optical nature of BC is well characterized, very little is known about the properties of light-absorbing OC (LAOC). Here, we report our preliminary findings on the mass-based optical properties of LAOC emitted from the combustion of four commonly used solid biomass fuels - fuel-wood, agricultural residue, dung-cake, and mixed - in traditional Indian cookstoves. As part of a pilot field study conducted in central India, PM2.5 samples were collected on Teflon filters and analyzed for their absorbance spectra in the 300-900 nm wavelengths at 1 nm resolution using a UV-Visible spectrophotometer equipped with an integrating sphere. The mean mass absorption cross-sections (MAC) of the emitted PM2.5 and OC, at 550 nm, were 0.8 and 0.2 m2 g-1, respectively, each with a factor of ~2.3 uncertainty. The mean absorption Ångström exponent (AǺE) values for PM2.5 were 3±1 between 350 and 550 nm, and 1.2±0.1 between 550 and 880 nm. In the 350-550 nm range, OC had an AǺE of 6.3±1.8. The emitted OC mass, which was on average 25 times of the BC mass, contributed over 50% of the aerosol absorbance at wavelengths smaller than 450 nm. The overall OC contribution to visible solar light (300-900 nm) absorption by the emitted particles was 26-45%. Our results highlight the need to comprehensively and accurately address: (i) the climatic impacts of light absorption by OC from cookstove emissions, and (ii) the uncertainties and biases associated with variability in biomass fuel types and combustion conditions, and filter-based measurement artifacts during determination of MAC values.

  11. Climatology of aerosol optical properties and black carbon mass absorption cross section at a remote high-altitude site in the western Mediterranean Basin

    NASA Astrophysics Data System (ADS)

    Pandolfi, M.; Ripoll, A.; Querol, X.; Alastuey, A.

    2014-06-01

    Aerosol light scattering (σsp), backscattering (σbsp) and absorption (σap) were measured at Montsec (MSC; 42°3' N, 0°44' E, 1570 m a.s.l.), a remote high-altitude site in the western Mediterranean Basin. Mean (±SD) σsp, σbsp and σap were 18.9 ± 20.8, 2.6 ± 2.8 and 1.5 ± 1.4 Mm-1, respectively at 635 nm during the period under study (June 2011-June 2013). Mean values of single-scattering albedo (SSA, 635 nm), the scattering Ångström exponent (SAE, 450-635 nm), backscatter-to-scatter ratio (B / S, 635 nm), asymmetry parameter (g, 635 nm), black carbon mass absorption cross section (MAC, 637 nm) and PM2.5 mass scattering cross section (MSCS, 635 nm) were 0.92 ± 0.03, 1.56 ± 0.88, 0.16 ± 0.09, 0.53 ± 0.16, 10.9 ± 3.5 m2 g-1 and 2.5 ± 1.3 m2 g-1, respectively. The scattering measurements performed at MSC were in the medium/upper range of values reported by Andrews et al. (2011) for other mountaintop sites in Europe due to the frequent regional recirculation scenarios (SREG) and Saharan dust episodes (NAF) occurring mostly in spring/summer and causing the presence of polluted layers at the MSC altitude. However, the development of upslope winds and the possible presence of planetary boundary layer air at MSC altitude in summer may also have contributed to the high scattering observed. Under these summer conditions no clear diurnal cycles were observed for the measured extensive aerosol optical properties (σsp, σbsp and σap). Conversely, low σsp and σap at MSC were measured during Atlantic advections (AA) and winter regional anticyclonic episodes (WREG) typically observed during the cold season in the western Mediterranean. Therefore, a season-dependent decrease in the magnitude of aerosol extensive properties was observed when MSC was in the free troposphere, with the highest free-troposphere vs. all-data difference observed in winter and the lowest in spring/summer. The location of MSC station allowed for a reliable characterization of aerosols

  12. Average absorption cross-section of the human body measured at 1-12 GHz in a reverberant chamber: results of a human volunteer study

    NASA Astrophysics Data System (ADS)

    Flintoft, I. D.; Robinson, M. P.; Melia, G. C. R.; Marvin, A. C.; Dawson, J. F.

    2014-07-01

    The electromagnetic absorption cross-section (ACS) averaged over polarization and angle-of-incidence of 60 ungrounded adult subjects was measured at microwave frequencies of 1-12 GHz in a reverberation chamber. Average ACS is important in non-ionizing dosimetry and exposure studies, and is closely related to the whole-body averaged specific absorption rate (WBSAR). The average ACS was measured with a statistical uncertainty of less than 3% and high frequency resolution for individuals with a range of body shapes and sizes allowing the statistical distribution of WBSAR over a real population with individual internal and external morphologies to be determined. The average ACS of all subjects was found to vary from 0.15 to 0.4 m2 for an individual subject it falls with frequency over 1-6 GHz, and then rises slowly over the 6-12 GHz range in which few other studies have been conducted. Average ACS and WBSAR are then used as a surrogate for worst-case ACS/WBSAR, in order to study their variability across a real population compared to literature results from simulations using numerical phantoms with a limited range of anatomies. Correlations with body morphological parameters such as height, mass and waist circumference have been investigated: the strongest correlation is with body surface area (BSA) at all frequencies above 1 GHz, however direct proportionality to BSA is not established until above 5 GHz. When the average ACS is normalized to the BSA, the resulting absorption efficiency shows a negative correlation with the estimated thickness of subcutaneous body fat. Surrogate models and statistical analysis of the measurement data are presented and compared to similar models from the literature. The overall dispersion of measured average WBSAR of the sample of the UK population studied is consistent with the dispersion of simulated worst-case WBSAR across multiple numerical phantom families. The statistical results obtained allow the calibration of human exposure

  13. Two-Photon Ratiometric Fluorescence Probe with Enhanced Absorption Cross Section for Imaging and Biosensing of Zinc Ions in Hippocampal Tissue and Zebrafish.

    PubMed

    Li, Wanying; Fang, Bingqing; Jin, Ming; Tian, Yang

    2017-02-21

    Zinc ion (Zn(2+)) not only plays an important function in the structural, catalytic, transcription, and regulatory of proteins, but is also an essential ionic signal to regulate brain neurotransmitters pass process. In this work, we designed and synthesized an intramolecular charge transfer-based ratiometric two-photon fluorescence probe, P-Zn, for imaging and biosensing of Zn(2+) in live cell, hippocampal tissue, and zebrafish. The developed probe demonstrated high two-photon absorption cross section (δ) of 516 ± 77 GM, which increased to 958 ± 144 GM after the probe was coordinated with Zn(2+). Furthermore, this P-Zn probe quickly recognized Zn(2+) with high selectivity, over other metal ions, amino acids, and reactive oxygen species. More interestingly, the initial emission peak of the present probe at 465 nm decreased with a new peak increased at 550 nm, leading to the ratiometric determination of Zn(2+) with high accuracy. Finally, this two-photon fluorescence probe with high temporal resolution and remarkable analytical performance, as well as low-cytotoxicity, was successfully applied in imaging of live cells, hippocampal tissues, and zebrafishes. The present P-Zn probe combined with FLIM provided accurate mapping of Zn(2+) distribution at single-cell level. More interestingly, the two-photon spectroscopic results demonstrated that the level of Zn(2+) in hippocampal tissue of mouse with AD was higher than that in normal mouse brain.

  14. Probiotic strain Lactobacillus plantarum 299v increases iron absorption from an iron-supplemented fruit drink: a double-isotope cross-over single-blind study in women of reproductive age.

    PubMed

    Hoppe, Michael; Önning, Gunilla; Berggren, Anna; Hulthén, Lena

    2015-10-28

    Iron deficiency is common, especially among young women. Adding probiotics to foods could be one way to increase iron absorption. The aim of this study was to test the hypothesis that non-haem iron absorption from a fruit drink is improved by adding Lactobacillus plantarum 299v (Lp299v). Iron absorption was studied in healthy women of reproductive age using a single-blind cross-over design in two trials applying the double-isotope (55Fe and 59Fe) technique. In Trial 1, iron absorption from a fruit drink containing 109 colony-forming units (CFU) Lp299v was compared with that from a control drink without Lp299v. Trial 2 had the same design but 1010 CFU were used. The test and control drinks contained approximately 5 mg of iron as ferrous lactate and were labelled with 59Fe (B) and 55Fe (A), respectively, and consumed on 4 consecutive days in the order AABB. Retention of the isotopes was measured with whole-body counting and in blood. Mean iron absorption from the drink containing 109 CFU Lp299v (28·6(sd 12·5) %) was significantly higher than from the control drink (18·5(sd 5·8) %), n 10, P<0·028). The fruit drink with 1010 CFU Lp299v gave a mean iron absorption of 29·1(sd 17·0) %, whereas the control drink gave an absorption of (20·1(sd 6·4) %) (n 11, P<0·080). The difference in iron absorption between the 109 CFU Lp299v and the 1010 CFU Lp299v drinks was not significant (P=0·941). In conclusion, intake of probiotics can increase iron absorption by approximately 50 % from a fruit drink having an already relatively high iron bioavailability.

  15. Atmospheric Chemistry of 1-Methoxy 2-Propyl Acetate: UV Absorption Cross Sections, Rate Coefficients, and Products of Its Reactions with OH Radicals and Cl Atoms.

    PubMed

    Zogka, Antonia G; Mellouki, Abdelwahid; Romanias, Manolis N; Bedjanian, Yuri; Idir, Mahmoud; Grosselin, Benoit; Daële, Véronique

    2016-11-17

    The rate coefficients for the reactions of OH and Cl with 1-methoxy 2-propyl acetate (MPA) in the gas phase were measured using absolute and relative methods. The kinetic study on the OH reaction was conducted in the temperature (263-373) K and pressure (1-760) Torr ranges using the pulsed laser photolysis-laser-induced fluorescence technique, a low pressure fast flow tube reactor-quadrupole mass spectrometer, and an atmospheric simulation chamber/GC-FID. The derived Arrhenius expression is kMPA+OH(T) = (2.01 ± 0.02) × 10(-12) exp[(588 ± 123/T)] cm(3) molecule(-1) s(-1). The absolute and relative rate coefficients for the reaction of Cl with MPA were measured at room temperature in the flow reactor and the atmospheric simulation chamber, which led to k(Cl+MPA) = (1.98 ± 0.31) × 10(-10) cm(3) molecule(-1) s(-1). GC-FID, GC-MS, and FT-IR techniques were used to investigate the reaction mechanism in the presence of NO. The products formed from the reaction of MPA with OH and their yields were methyl formate (80 ± 7.3%), acetic acid (50 ± 4.8%), and acetic anhydride (22 ± 2.4%), while for Cl reaction, the obtained yields were 60 ± 5.4, 41 ± 3.8, and 11 ± 1.2%, respectively, for the same products. The UV absorption cross section spectrum of MPA was determined in the wavelength range 210-370 nm. The study has shown no photolysis of MPA under atmospheric conditions. The obtained results are used to derive the atmospheric implication.

  16. Porosity estimates on basaltic basement samples using the neutron absorption cross section (Σ): Implications for fluid flow and alteration of the oceanic crust

    NASA Astrophysics Data System (ADS)

    Reichow, M. K.; Brewer, T. S.; Marvin, L. G.; Lee, S. V.

    2008-12-01

    Little information presently exists on the heterogeneity of hydrothermal alteration in the oceanic crust or the variability of the associated thermal, fluid, and chemical fluxes. Formation porosities are important controls on these fluxes and porosity measurements are routinely collected during wireline logging operations. These estimates on the formation porosity are measures of the moderating power of the formation in response to bombardment by neutrons. The neutron absorption macroscopic cross-section (Σ = σρ) is a representation of the ability of the rock to slow down neutrons, and as such can be used to invert the porosity of a sample. Boron, lithium and other trace elements are important controls on σ-values, and the distribution of these is influenced by secondary low-temperature alteration processes. Consequently, computed σ-values may be used to discriminate between various basalt types and to identify areas of secondary alteration. Critical in this analysis is the degree of alteration, since elements such as B and Li can dramatically affect the sigma value and leading to erroneous porosity values. We analysed over 150 'pool-samples' for S, Li, Be and B element concentrations to estimate their contribution to the measured neutron porosity. These chemical analyses allow the calculation of the model sigma values for individual samples. Using a range of variably altered samples recovered during IODP Expeditions 309 and 312 we provide bulk estimates of alteration within the drilled section using the measured neutron porosity. B concentration in Hole 1256D increases with depth, with sharp rises at 959 and 1139 mbsf. Elevated wireline neutron porosities cannot always be directly linked with high B content. However, our preliminary results imply that increased neutron porosity (~15) at depths below 1100 mbsf may reflect hydrothermal alteration rather than formation porosity. This interpretation is supported when compared with generally lower computed

  17. ABSORPTION ANALYZER

    DOEpatents

    Brooksbank, W.A. Jr.; Leddicotte, G.W.; Strain, J.E.; Hendon, H.H. Jr.

    1961-11-14

    A means was developed for continuously computing and indicating the isotopic assay of a process solution and for automatically controlling the process output of isotope separation equipment to provide a continuous output of the desired isotopic ratio. A counter tube is surrounded with a sample to be analyzed so that the tube is exactly in the center of the sample. A source of fast neutrons is provided and is spaced from the sample. The neutrons from the source are thermalized by causing them to pass through a neutron moderator, and the neutrons are allowed to diffuse radially through the sample to actuate the counter. A reference counter in a known sample of pure solvent is also actuated by the thermal neutrons from the neutron source. The number of neutrons which actuate the detectors is a function of a concentration of the elements in solution and their neutron absorption cross sections. The pulses produced by the detectors responsive to each neu tron passing therethrough are amplified and counted. The respective times required to accumulate a selected number of counts are measured by associated timing devices. The concentration of a particular element in solution may be determined by utilizing the following relation: T2/Ti = BCR, where B is a constant proportional to the absorption cross sections, T2 is the time of count collection for the unknown solution, Ti is the time of count collection for the pure solvent, R is the isotopic ratlo, and C is the molar concentration of the element to be determined. Knowing the slope constant B for any element and when the chemical concentration is known, the isotopic concentration may be readily determined, and conversely when the isotopic ratio is known, the chemical concentrations may be determined. (AEC)

  18. Laboratory studies of some halogenated ethanes and ethers: Measurements of rates of reaction with OH and of infrared absorption cross-sections

    NASA Astrophysics Data System (ADS)

    Brown, Anne C.; Canosa-Mas, Carlos E.; Douglas Parr, A.; Wayne, Richard P.

    We have measured, using a conventional discharge-flow resonance-fluorescence technique, the rates of reaction between the hydroxyl radical and a series of halogenated ethanes and ethers for the temperature range 230-423 K. Our measurements gave the following Arrhenius expressions (units are cm 3 molecule -1 s -1): CF 2HCH 3 (HFC-152), 14.2 × 10 -13 exp-(1050/ T); CF 2ClCH 3 (HCFC-142b), 2.6 × 10 -13 exp-(1230/ T); CFCl 2CH 3 (HCFC-141b), 5.8 × 10 -13 exp-(1100/ T); CF 3CFH 2 (HFC-134a), 5.8 × 10 -13 exp-(1350/ T); CF 3CF 2H (HFC-125), 2.8 × 10 -13 exp-(1350/ T); CF 3CCl 2H (HCFC-123), 11.8 × 10 -13 exp-(900/ T); CF 2HOCF 2CFClH, (enflurane), 6.1 × 10 -13 exp-(1080/ T); CFH 2OCH(CF 3) 2, (sevoflurane), 15.3 × 10 -13 exp-(900/ T). In two cases, we measured rate constants only at room temperature: CF 3CClBrH (halothane), 6 × 10 -14 and CF 2HOCClHCF 3 (isoflurane), 2.1 × 10 -14. We also report the following values for the integrated absorption cross-sections of the compounds in the spectral region 800-1200 cm -1 in units of cm -2 atm -1: CF 2HCH 3, 1155; CF 2ClCH 3, 1422; CFCl 2CH 3, 1995; CF 3CFH 2, 2686; CF 3CF 2H, 1970, CF 3CCl 2H, 1411; CF 3CClBrH, 1400; CF 2HOCF 2CFClH, 4800; CF 2HOCClHCF 3, 3900; CFH 2OCH(CF 3) 2, 2550. We use our measurements to calculate ozone depletion potentials and greenhouse warming potentials relative to CFCl 3 for each compound.

  19. Study of the OH and Cl-initiated oxidation, IR absorption cross-section, radiative forcing, and global warming potential of four C4-hydrofluoroethers.

    PubMed

    Oyaro, Nathan; Sellevåg, Stig R; Nielsen, Claus J

    2004-11-01

    Infrared absorption cross-sections and OH and Cl reaction rate coefficients for four C4-hydrofluoroethers (CF3)2CHOCH3, CF3CH2OCH2CF3, CF3CF2CH2OCH3, and CHF2CF2CH2OCH3 are reported. Relative rate measurements at 298 K and 1013 hPa of OH and Cl reaction rate coefficients give k(OH+(CF3)2CHOCH3) = (1.27+/-0.13) x 10(-13), k(OH+CF3CH2OCH2CF3) = (1.51+/-0.24) x 10(-13), k(OH+CF3CF2CH2OCH3) = (6.42+/-0.33) x 10(-13), k(OH+CHF2CF2CH2OCH3) = (8.7 +/-0.5) x 10(-13), k(Cl+(CF3)2CHOCH3) = (8.4+/-1.3) x 10(-12), k(Cl+CF3CH2OCH2CF3) = (6.5+/-1.7) x 10(-13), k(Cl+CF3CF2CH2OCH3) = (4.0+/-0.8) x 10(-11), and k(Cl+CHF2CF2CH2OCH3) = (2.65+/-0.17) x 10(-11) cm3 molecule(-1) s(-1). The primary products of the OH and Cl reactions with the fluorinated ethers have been identified as esters, and OH and Cl reaction rate coefficients for one of these, CF3CH2OCHO, are reported: k(OH+CF3CH2OCHO) = (7.7+/-0.9) x 10(-14) and kCl+CF3CH2OCHO) = (6.3+/-1.9) x 10(-14) cm3 molecule(-1) s(-1) The rate coefficient for the Cl-atom reaction with CHF2CH2F is derived as k(Cl+CHF2CH2F) = (3.0+/-0.9) x 10(-14) cm3 molecule(-1) s(-1) at 298 K. The error limits include 3sigma from the statistical data analyses as well as the errors in the rate coefficients of the reference compounds employed. The tropospheric lifetimes of the hydrofluoroethers are estimated to be short tauOH((CF3)2CHOCH3) approximately 100 days, tauOH(CF3CH2OCH2CF3) approximately 80 days, tauOH(CF3CF2CH2OCH3) approximately 20 days, and tauOH(CHF2CF2CH2OCH3) approximately 14 days, and their global warming potentials are small compared to CFC-11.

  20. Nonlinear optical absorption and stimulated Mie scattering in metallic nanoparticle suspensions

    NASA Astrophysics Data System (ADS)

    He, Guang S.; Law, Wing-Cheung; Baev, Alexander; Liu, Sha; Swihart, Mark T.; Prasad, Paras N.

    2013-01-01

    The nonlinear optical properties of four metallic (Au-, Au/Ag-, Ag-, and Pt-) nanoparticle suspensions in toluene have been studied in both femtosecond and nanosecond regimes. Nonlinear transmission measurements in the femtosecond laser regime revealed two-photon absorption (2PA) induced nonlinear attenuation, while in the nanosecond laser regime a stronger nonlinear attenuation is due to both 2PA and 2PA-induced excited-state absorption. In the nanosecond regime, at input pump laser intensities above a certain threshold value, a new type of stimulated (Mie) scattering has been observed. Being essentially different from all other well known molecular (Raman, Brillouin) stimulated scattering effects, the newly observed stimulated Mie scattering from the metallic nanoparticles exhibits the features of no frequency shift and low pump threshold requirement. A physical model of induced Bragg grating initiated by the backward Mie scattering from metallic nanoparticles is proposed to explain the gain mechanism of the observed stimulated scattering effect.

  1. Maternal post-absorptive leucine kinetics during late pregnancy in US women with HIV taking antiretroviral therapy: a cross-sectional pilot study

    PubMed Central

    Cade, W. Todd; Singh, Gautam K.; Holland, Mark R.; Reeds, Dominic N.; Overton, E. Turner; Cibulka, Nancy; Bahow, Karen; Presti, Rachel; Stephens, Andrea; Cahill, Alison G.

    2015-01-01

    Background Despite the success of combination antiretroviral therapy (cART) for the prevention of mother to child transmission of HIV, infants exposed to cART in utero frequently are born smaller and have mild cardiac abnormalities. The mechanisms responsible for lower birth weight and cardiac abnormalities in children exposed to cART are unclear but could be related to dysregulation of maternal amino acid metabolism during pregnancy. Previous data in HIV(−) women have shown a relationship between abnormal maternal protein metabolism during pregnancy and low infant birth weight and animal data demonstrate a relationship between altered maternal protein metabolism and increased risk for offspring cardiovascular abnormalities. Objective The objectives of this study were to: characterize post-absorptive maternal leucine kinetics during late pregnancy and examine the relationships between maternal leucine kinetics and offspring birth weight and cardiac function. Design Post-absorptive maternal leucine kinetics (evaluated by using stable isotope tracer methodology) in 16 HIV(+) women receiving cART and 14 HIV(−) US women during the 3rd trimester of pregnancy were compared. Relationships between post-absorptive maternal leucine kinetics, cardiac function (echocardiography) and birth weight were statistically examined. Results Maternal plasma leucine concentration (HIV(−): 82.8 ± 10.7 vs. HIV(+): 72.3 ± 13.5 μM, p=0.06) and leucine oxidation rate (HIV(−): 6.1 ± 1.6 vs. HIV(+): 4.9 ± 1.8 μmol/kgBW/min, p=0.03) were lower in HIV+ women compared to controls. Total leucine turnover rate, non-oxidative leucine disposal rate and post-absorptive maternal glucose and palmitate kinetics did not differ between groups. Left ventricular fractional shortening tended to be lower in children born to HIV(+) compared to controls (HIV(−): 42 ± 1 vs. HIV+: 36 ± 5 %, p=0.08) and associated with lower maternal plasma leucine concentration (r= 0.43, p=0.08). Conclusions

  2. A new direct infrared laser absorption method for state-to-state rotational energy transfer in crossed supersonic jets: Experimental results and quantum scattering analysis for Ar+CH4

    NASA Astrophysics Data System (ADS)

    Nesbitt, David J.; Nibler, Joseph W.; Schiffman, Aram; Chapman, William B.; Hutson, Jeremy M.

    1993-06-01

    A new method for measuring state-to-state rotational energy transfer in crossed supersonic beams is described. The method is based on direct absorption of tunable, high-resolution infrared laser light by target molecules collisionally excited into final rotational states. The direct IR absorption approach offers high sensitivity, full quantum state resolution, a Doppler probe of final velocity components, and is applicable to any target molecule that absorbs in the near IR. Preliminary results are presented for Ar+CH4 scattering in crossed supersonic beams at a mean center-of-mass collision energy of 41 meV. Because of the high spectral resolution, the method can readily distinguish rotational fine structure states of A, F, and E symmetry in the tetrahedral group, as well as the much more energetically separated final j states. The results are compared with full quantum close-coupling calculations on two different Ar+CH4 potential energy surfaces. The state-to-state scattering results provide a sensitive measure of the potential anisotropy, and in particular probe the relative magnitudes of the different anisotropic terms in the potential (V3 and V4).

  3. Red emissive AIE nanodots with high two-photon absorption efficiency at 1040 nm for deep-tissue in vivo imaging.

    PubMed

    Wang, Yalun; Hu, Rongrong; Xi, Wang; Cai, Fuhong; Wang, Shaowei; Zhu, Zhenfeng; Bai, Rongpan; Qian, Jun

    2015-10-01

    Deep-tissue penetration is highly required in in vivo optical bioimaging. We synthesized a type of red emissive fluorophore BT with aggregation-induced emission (AIE) property. BT molecules were then encapsulated with amphiphilic polymers to form nanodots, and a large two-photon absorption (2PA) cross-section of 2.9 × 10(6) GM at 1040 nm was observed from each BT nanodot, which was much larger than those at the wavelengths of 770 to 860 nm. In addition, 1040 nm light was found to have better penetration and focusing capability than 800 nm light in biological tissue, according to the Monte Carlo simulation. The toxicity and tissue distribution of BT nanodots were studied, and they were found to have good biocompatibility. BT nanodots were then utilized for in vivo imaging of mouse ear and brain, and an imaging depth of 700 μm was obtained with the femtosecond (fs) excitation of 1040 nm. The red emissive AIE nanodots with high 2PA efficiency at 1040 nm would be useful for deep-tissue functional bioimaging in the future.

  4. Red emissive AIE nanodots with high two-photon absorption efficiency at 1040 nm for deep-tissue in vivo imaging

    PubMed Central

    Wang, Yalun; Hu, Rongrong; Xi, Wang; Cai, Fuhong; Wang, Shaowei; Zhu, Zhenfeng; Bai, Rongpan; Qian, Jun

    2015-01-01

    Deep-tissue penetration is highly required in in vivo optical bioimaging. We synthesized a type of red emissive fluorophore BT with aggregation-induced emission (AIE) property. BT molecules were then encapsulated with amphiphilic polymers to form nanodots, and a large two-photon absorption (2PA) cross-section of 2.9 × 106 GM at 1040 nm was observed from each BT nanodot, which was much larger than those at the wavelengths of 770 to 860 nm. In addition, 1040 nm light was found to have better penetration and focusing capability than 800 nm light in biological tissue, according to the Monte Carlo simulation. The toxicity and tissue distribution of BT nanodots were studied, and they were found to have good biocompatibility. BT nanodots were then utilized for in vivo imaging of mouse ear and brain, and an imaging depth of 700 μm was obtained with the femtosecond (fs) excitation of 1040 nm. The red emissive AIE nanodots with high 2PA efficiency at 1040 nm would be useful for deep-tissue functional bioimaging in the future. PMID:26504629

  5. Neutron Absorption in Geological Material

    NASA Astrophysics Data System (ADS)

    Løvhøiden, G.; Andersen, E.

    1990-01-01

    Thermal neutron absorption cross section of geological samples is determined with the steady state neutron source method. Cross section measurements of North Sea sediments demonstrate that also materials with high contents of clay minerals may be investigated with the steady state method.

  6. Ultraviolet absorption spectrum of HOCl

    NASA Technical Reports Server (NTRS)

    Burkholder, James B.

    1993-01-01

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

  7. Reliable Potential Energy Surfaces for the Reactions of H2O with ThO2, PaO2(+), UO2(2+), and UO2(.).

    PubMed

    Vasiliu, Monica; Peterson, Kirk A; Gibson, John K; Dixon, David A

    2015-11-19

    The potential energy surfaces for the reactions of H2O with ThO2, PaO2(+), UO2(2+), and UO2(+) have been calculated at the coupled cluster CCSD(T) level extrapolated to the complete basis set limit with additional corrections including scalar relativistic and spin-orbit. The reactions proceed by the formation of an initial Lewis acid-base adduct (H2O)AnO2(0/+/2+) followed by a proton transfer to generate the dihydroxide AnO(OH)2(0/+/2+). The results are in excellent agreement with mass spectrometry experiments and prior calculations of hydrolysis reactions of the group 4 transition metal dioxides MO2. The differences in the energies of the stationary points on the potential energy surface are explained in terms of the charges on the system and the populations on the metal center. The use of an improved starting point for the coupled cluster CCSD(T) calculations based on density functional theory with the PW91 exchange-correlation functional or Brueckner orbitals is described. The importance of including second-order spin-orbit corrections for closed-shell molecules is also described. These improvements in the calculations are correlated with the 5f populations on the actinide.

  8. Non-resonant below-bandgap two-photon absorption in quantum dot solar cells

    SciTech Connect

    Li, Tian; Dagenais, Mario

    2015-04-27

    We study the optically nonlinear sub-bandgap photocurrent generation facilitated by an extended tailing distribution of states in an InAs/GaAs quantum dots (QDs) solar cell. The tailing states function as both the energy states for low energy photon absorption and the photocarriers extraction pathway. One of the biggest advantages of our method is that it can clearly differentiate the photocurrent due to one-photon absorption (1PA) process and two-photon absorption (2PA) process. Both 1PA and 2PA photocurrent generation efficiency in an InAs/GaAs QD device operated at 1550 nm have been quantitatively evaluated. A two-photon absorption coefficient β = 5.7 cm/GW is extracted.

  9. A study of the temperature dependence of the infrared absorption cross-sections of 2,2,3,3,3-pentafluoropropanol in the range of 298-362 K

    NASA Astrophysics Data System (ADS)

    Godin, Paul J.; Cabaj, Alex; Xu, Li-Hong; Le Bris, Karine; Strong, Kimberly

    2017-01-01

    Absorption cross-sections of 2,2,3,3,3-pentafluoropropanol (PFPO) were derived from Fourier transform infrared spectra recorded from 565 to 3400 cm-1 with a resolution of 0.1 cm-1 over a temperature range of 298-362 K. These results were compared to previously published theoretical density functional theory (DFT) calculations and experimental measurements made at room temperature. We find good agreement between our experimentally derived results, DFT calculations, and previously published data. The only temperature dependence observed was in the centroid shift of the 850-1500 cm-1 band and in the amplitude of some of the absorption peaks. However, this temperature dependence does not result in a significant trend in integrated band strength as a function of temperature. We calculate an average integrated band strength of (1.991±0.001)×10-16 cm molecule-1 for PFPO over the spectral range studied. Radiative efficiencies (REs) and the global warming potential (GWP) for PFPO were also derived. We find an average RE of 0.2603 ± 0.0007 Wm-2ppbv-1 and a GWP100 of 19.8. The calculated radiative efficiencies show that no dependence on temperature and our findings are consistent with previous studies, increasing our confidence in the value of the GWP of PFPO.

  10. Temperature dependence of the NO3 absorption cross-section above 298 K and determination of the equilibrium constant for NO3 + NO2 <--> N2O5 at atmospherically relevant conditions.

    PubMed

    Osthoff, Hans D; Pilling, Michael J; Ravishankara, A R; Brown, Steven S

    2007-11-21

    The reaction NO3 + NO2 <--> N2O5 was studied over the 278-323 K temperature range. Concentrations of NO3, N2O5, and NO2 were measured simultaneously in a 3-channel cavity ring-down spectrometer. Equilibrium constants were determined over atmospherically relevant concentration ranges of the three species in both synthetic samples in the laboratory and ambient air samples in the field. A fit to the laboratory data yielded Keq = (5.1 +/- 0.8) x 10(-27) x e((10871 +/- 46)/7) cm3 molecule(-1). The temperature dependence of the NO3 absorption cross-section at 662 nm was investigated over the 298-388 K temperature range. The line width was found to be independent of temperature, in agreement with previous results. New data for the peak cross section (662.2 nm, vacuum wavelength) were combined with previous measurements in the 200 K-298 K region. A least-squares fit to the combined data gave sigma = [(4.582 +/- 0.096) - (0.00796 +/- 0.00031) x T] x 10(-17) cm2 molecule(-1).

  11. Hydroxyl radical reaction rate coefficients as a function of temperature and IR absorption cross sections for CF3CH=CH2 (HFO-1243zf), potential replacement of CF3CH2F (HFC-134a).

    PubMed

    González, Sergio; Jiménez, Elena; Ballesteros, Bernabé; Martínez, Ernesto; Albaladejo, José

    2015-04-01

    CF3CH=CH2 (hydrofluoroolefin, HFO-1243zf) is a potential replacement of high global-warming potential (GWP) hydrofluorocarbon (HFC-134a, CF3CFH2). Both the atmospheric lifetime and the radiative efficiency of HFO-1243zf are parameters needed for estimating the GWP of this species. Therefore, the aim of this work is (i) to estimate the atmospheric lifetime of HFO-1243zf from the reported OH rate coefficients, k OH, determined under tropospheric conditions and (ii) to calculate its radiative efficiency from the reported IR absorption cross sections. The OH rate coefficient at 298 K also allows the estimation of the photochemical ozone creation potential (ε(POCP)). The pulsed laser photolysis coupled to a laser-induced fluorescence technique was used to determine k OH for the reaction of OH radicals with HFO-1243zf as a function of pressure (50-650 Torr of He) and temperature (263-358 K). Gas-phase IR spectra of HFO-1243zf were recorded at room temperature using a Fourier transform IR spectrometer between 500 and 4,000 cm(-1). At all temperatures, k OH did not depend on bath gas concentration (i.e., on the total pressure between 50 and 650 Torr of He). A slight but noticeable T dependence of k OH was observed in the temperature range investigated. The observed behavior is well described by the following Arrhenius expression: k OH(T) = (7.65 ± 0.26) × 10(-13) exp [(165 ± 10) / T] cm(3) molecule(-1) s(-1). Negligible IR absorption of HFO-1243zf was observed at wavenumbers greater than 1,700 cm(-1). Therefore, IR absorption cross sections, [Formula: see text], were determined in the 500-1,700 cm(-1) range. Integrated [Formula: see text] were determined between 650 and 1,800 cm(-1) for comparison purposes. The main diurnal removal pathway for HFO-1243zf is the reaction with OH radicals, which accounts for 64% of the overall loss by homogeneous reactions at 298 K. Globally, the lifetime due to OH reaction (τ OH) was estimated to be 8.7 days under

  12. Two-Photon Absorption Spectrum of a Single Crystal Cyanine-like Dye.

    PubMed

    Hu, Honghua; Fishman, Dmitry A; Gerasov, Andrey O; Przhonska, Olga V; Webster, Scott; Padilha, Lazaro A; Peceli, Davorin; Shandura, Mykola; Kovtun, Yuriy P; Kachkovski, Alexey D; Nayyar, Iffat H; Masunov, Artëm E; Tongwa, Paul; Timofeeva, Tatiana V; Hagan, David J; Van Stryland, Eric W

    2012-05-03

    The two-photon absorption (2PA) spectrum of an organic single crystal is reported. The crystal is grown by self-nucleation of a subsaturated hot solution of acetonitrile, and is composed of an asymmetrical donor-π-acceptor cyanine-like dye molecule. To our knowledge, this is the first report of the 2PA spectrum of single crystals made from a cyanine-like dye. The linear and nonlinear properties of the single crystalline material are investigated and compared with the molecular properties of a toluene solution of its monomeric form. The maximum polarization-dependent 2PA coefficient of the single crystal is 52 ± 9 cm/GW, which is more than twice as large as that for the inorganic semiconductor CdTe with a similar absorption edge. The optical properties, linear and nonlinear, are strongly dependent upon incident polarization due to anisotropic molecular packing. X-ray diffraction analysis shows π-stacking dimers formation in the crystal, similar to H-aggregates. Quantum chemical calculations demonstrate that this dimerization leads to the splitting of the energy bands and the appearance of new red-shifted 2PA bands when compared to the solution of monomers. This trend is opposite to the blue shift in the linear absorption spectra upon H-aggregation.

  13. PERITONEAL ABSORPTION

    PubMed Central

    Hahn, P. F.; Miller, L. L.; Robscheit-Robbins, F. S.; Bale, W. F.; Whipple, G. H.

    1944-01-01

    The absorption of red cells from the normal peritoneum of the dog can be demonstrated by means of red cells labeled with radio-iron incorporated in the hemoglobin of these red cells. Absorption in normal dogs runs from 20 to 100 per cent of the amount given within 24 hours. Dogs rendered anemic by bleeding absorb red cells a little less rapidly—ranging from 5 to 80 per cent of the injected red cells. Doubly depleted dogs (anemic and hypoproteinemic) absorb even less in the three experiments recorded. This peritoneal absorption varies widely in different dogs and even in the same dog at different times. We do not know the factors responsible for these variations but there is no question about active peritoneal absorption. The intact red cells pass readily from the peritoneal cavity into lymph spaces in diaphragm and other areas of the peritoneum. The red cells move along the lymphatics and through the lymph glands with little or no phagocytosis and eventually into the large veins through the thoracic ducts. PMID:19871404

  14. Nutrient absorption.

    PubMed

    Rubin, Deborah C

    2004-03-01

    Our understanding of nutrient absorption continues to grow, from the development of unique animal models and from studies in which cutting-edge molecular and cellular biologic approaches have been used to analyze the structure and function of relevant molecules. Studies of the molecular genetics of inherited disorders have also provided many new insights into these processes. A major advance in lipid absorption has been the cloning and characterization of several intestinal acyl CoA:monoacylglycerol acyltransferases; these may provide new targets for antiobesity drug therapy. Studies of intestinal cholesterol absorption and reverse cholesterol transport have encouraged the development of novel potential treatments for hyperlipidemia. Observations in genetically modified mice and in humans with mutations in glucose transporter 2 suggest the importance of a separate microsomal membrane transport pathway for glucose transport. The study of iron metabolism has advanced greatly with the identification of the hemochromatosis gene and the continued examination of the genetic regulation of iron absorptive pathways. Several human thiamine transporters have been identified, and their specific roles in different tissues are being explored.

  15. Effect of sexual intercourse on the absorption of levonorgestrel after vaginal administration of 0.75 mg in Carraguard® gel: a randomized, cross-over, pharmacokinetic study☆

    PubMed Central

    Brache, Vivian; Croxatto, Horacio; Kumar, Narender; Sitruk-Ware, Regine; Cochón, Leila; Schiappacasse, Veronica; Sivin, Irving; Muñoz, Carla; Maguire, Robin; Faundes, Anibal

    2010-01-01

    Background The Population Council studied a pre-coital contraceptive microbicide vaginal product containing levonorgestrel (LNG) as active component and Carraguard® gel as a vehicle (Carra/LNG gel) for couples who engage in occasional unplanned intercourse. The objective of this study was to evaluate the effect of sexual intercourse after vaginal application of Carra/LNG gel on serum levels of LNG in women and to assess LNG absorption by the male partner. Study Design This was a randomized, cross-over, pharmacokinetic study including an abstinence arm and an arm in which couples engaged in sexual intercourse between 2 and 4 h after gel application. In each study arm, each woman received a single application of Carra/LNG gel (0.75 mg in 4 mL gel) followed by serial blood samples taken at 0, 1, 2, 4, 8, 24 and 48 h after gel application for LNG measurements. In the intercourse arm, LNG was measured in blood samples taken from the male partner before intercourse and at 4, 8 and 24 h after gel application in the female partner. Results Time concentration curves for serum LNG levels showed a mean Cmax of 7.8±5.5 and 8.3±5.7 nmol/L, a mean Tmax of 6.2±5.9 and 7.5±5.7, and comparable area under the curve for the intercourse and abstinence arm, respectively. Pharmacokinetic parameters presented large variability between subjects, but excellent reproducibility within each subject. LNG was undetectable in 10 out of 12 male partners. Conclusion Sexual intercourse does not appear to interfere with vaginal absorption of LNG after application of a Carra/LNG gel. A vaginal pre-coital contraceptive gel is feasible. PMID:19135574

  16. Five-Photon Absorption and Selective Enhancement of Multiphoton Absorption Processes

    PubMed Central

    2015-01-01

    We study one-, two-, three-, four-, and five-photon absorption of three centrosymmetric molecules using density functional theory. These calculations are the first ab initio calculations of five-photon absorption. Even- and odd-order absorption processes show different trends in the absorption cross sections. The behavior of all even- and odd-photon absorption properties shows a semiquantitative similarity, which can be explained using few-state models. This analysis shows that odd-photon absorption processes are largely determined by the one-photon absorption strength, whereas all even-photon absorption strengths are largely dominated by the two-photon absorption strength, in both cases modulated by powers of the polarizability of the final excited state. We demonstrate how to selectively enhance a specific multiphoton absorption process. PMID:26120588

  17. Five-Photon Absorption and Selective Enhancement of Multiphoton Absorption Processes.

    PubMed

    Friese, Daniel H; Bast, Radovan; Ruud, Kenneth

    2015-05-20

    We study one-, two-, three-, four-, and five-photon absorption of three centrosymmetric molecules using density functional theory. These calculations are the first ab initio calculations of five-photon absorption. Even- and odd-order absorption processes show different trends in the absorption cross sections. The behavior of all even- and odd-photon absorption properties shows a semiquantitative similarity, which can be explained using few-state models. This analysis shows that odd-photon absorption processes are largely determined by the one-photon absorption strength, whereas all even-photon absorption strengths are largely dominated by the two-photon absorption strength, in both cases modulated by powers of the polarizability of the final excited state. We demonstrate how to selectively enhance a specific multiphoton absorption process.

  18. Methane Cross-Validation Between Spaceborne Solar Occultation Observations from ACE-FTS, Spaceborne Nadir Sounding from Gosat, and Ground-Based Solar Absorption Measurements, at a High Arctic Site.

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    We present cross-validation of remote sensing observations of methane profiles in the Canadian High Arctic. Methane is the third most important greenhouse gas on Earth, and second only to carbon dioxide in its contribution to anthropogenic global warming. Accurate and precise observations of methane are essential to understand quantitatively its role in the climate system and in global change. The Arctic is a particular region of concern, as melting permafrost and disappearing sea ice might lead to accelerated release of methane into the atmosphere. Global observations require spaceborne instruments, in particular in the Arctic, where surface measurements are sparse and expensive to perform. Satellite-based remote sensing is an underconstrained problem, and specific validation under Arctic circumstances is required. Here, we show a cross-validation between two spaceborne instruments and ground-based measurements, all Fourier Transform Spectrometers (FTS). We consider the Canadian SCISAT ACE-FTS, a solar occultation spectrometer operating since 2004, and the Japanese GOSAT TANSO-FTS, a nadir-pointing FTS operating at solar and terrestrial infrared wavelengths, since 2009. The ground-based instrument is a Bruker Fourier Transform Infrared (FTIR) spectrometer, measuring mid-infrared solar absorption spectra at the Polar Environmental and Atmospheric Research Laboratory (PEARL) at Eureka, Nunavut (80°N, 86°W) since 2006. Measurements are collocated considering temporal, spatial, and geophysical criteria and regridded to a common vertical grid. We perform smoothing on the higher-resolution instrument results to account for different vertical resolutions. Then, profiles of differences for each pair of instruments are examined. Any bias between instruments, or any accuracy that is worse than expected, needs to be understood prior to using the data. The results of the study will serve as a guideline on how to use the vertically resolved methane products from ACE and

  19. Full Spectral Resolution Data Generation from the Cross-track Infrared Sounder on S-NPP at NOAA and its Use to Investigate Uncertainty in Methane Absorption Band Near 7.66 µm

    NASA Astrophysics Data System (ADS)

    Xiong, X.; Peischl, J.; Ryerson, T. B.; Sasakawa, M.; Han, Y.; Chen, Y.; Wang, L.; Tremblay, D.; Jin, X.; Zhou, L.; Liu, Q.; Weng, F.; Machida, T.

    2015-12-01

    The Cross-track Infrared Sounder (CrIS) on Suomi National Polar-orbiting Partnership Satellite (S-NPP) is a Fourier transform spectrometer for atmospheric sounding. CrIS on S-NPP started to provide measurements in 1305 channels in its normal mode since its launch on November 2011 to December 4, 2014, and after that it was switched to the full spectral resolution (FSR) mode, in which the spectral resolutions are 0.625 cm-1 in all the MWIR (1210-1750 cm-1), SWIR (2155-2550 cm-1) and the LWIR bands (650-1095 cm-1) with a total of 2211 channels. While the NOAA operational Sensor Data Record (SDR) processing (IDPS) continues to produce the normal resolution SDRs by truncating full spectrum RDR data, NOAA STAR started to process the FSR SDRs data since December 4, 2014 to present, and the data is being delivered through NOAA STAR website (ftp://ftp2.star.nesdis.noaa.gov/smcd/xxiong/). The current FSR processing algorithm was developed on basis of the CrIS Algorithm Development Library (ADL), and is the baseline of J-1 CrIS SDR algorithm. One major benefit to use the FSR data is to improve the retrieval of atmospheric trace gases, such as CH4, CO and CO2 . From our previous studies to retrieve CH4 using Atmospheric Infrared Sounder (AIRS) and Infrared Atmospheric Sounding Interferometer (IASI), it was found the uncertainty in the CH4 absorption band is up to 1-2%. So, in this study we computed the radiance using the community radiative transfer model (CRTM) and line-by-line model, with the inputs of "truth" of atmospheric temperature and moisture profiles from ECMWF model (and/or RAOB sounding) and CH4 profiles from in-situ aircraft measurements, then convoluted with the response function of CrIS. The difference between the simultaed radiance and the collocated CrIS FSR data is used to exam the uncertainty in these strong absorption channels.Through the improved fitting to the transmittance in these channels, it is expected to improve the retrieval of CH4 using CrIS on S

  20. Degenerate two-photon absorption in all-trans retinal: nonlinear spectrum and theoretical calculations.

    PubMed

    Vivas, M G; Silva, D L; Misoguti, L; Zaleśny, R; Bartkowiak, W; Mendonca, C R

    2010-03-18

    In this work we investigate the degenerate two-photon absorption spectrum of all-trans retinal in ethanol employing the Z-scan technique with femtosecond pulses. The two-photon absorption (2PA) spectrum presents a monotonous increase as the excitation wavelength approaches the one-photon absorption band and a peak at 790 nm. We attribute the 2PA band to the mixing of states (1)B(u)(+)-like and |S(1)>, which are strongly allowed by one- and two-photon, respectively. We modeled the 2PA spectrum by using the sum-over-states approach and obtained spectroscopic parameters of the electronic transitions to |S(1)>, |S(2)> ("(1)B(u)(+)"), |S(3)>, and |S(4)> singlet-excited states. The results were compared with theoretical predictions of one- and two-photon transition calculations using the response functions formalism within the density functional theory framework with the aid of the CAM-B3LYP functional.

  1. Reflective-tube absorption meter

    NASA Astrophysics Data System (ADS)

    Zaneveld, J. Ronald V.; Bartz, Robert; Kitchen, James C.

    1990-09-01

    The design and calibration of a proposed in situ spectral absorption meter is evaluated using a laboratory prototype. The design includes a silver coated (second-surface) glass tube, a tungsten light source (stabilized by means of optical feedback), a monochromator, and a solid state detector. The device measures the absorption coefficient plus a portion of the volume scattering function. Theoretical analyses and laboratory experiments which explore the magnitude and variation of the errors due to scattering and internal reflections are described. Similar analyses are performed on the Cary 1 18 Spectrophotometer to allow cross calibration. Algorithms to yield the abscrption coefficient and the zenith-sun diffuse attenuation coefficient are presented and evaluated. Simultaneous measurement of the beam attenuation or backscattering coefficient allows use of algoriThms with much narrower error bands. The various methods of obtaining absorption and diffuse attenuation values are compared. Procedures for using reverse osmosis filtration to produce a clean water calibration standard are described. An absorption spectrum for pure water is obtained. Development of the absorption meter is proceeding along two lines: 1) a two-wavelength side-by-side LED is being fabricated to allow an in situ chlorophyll a absorption meter to be constructed, and 2) scientific projects using a shipboard or laboratory flow.-through pumping system are being planned.

  2. Geometrical interpretation of optical absorption

    SciTech Connect

    Monzon, J. J.; Barriuso, A. G.; Sanchez-Soto, L. L.; Montesinos-Amilibia, J. M.

    2011-08-15

    We reinterpret the transfer matrix for an absorbing system in very simple geometrical terms. In appropriate variables, the system appears as performing a Lorentz transformation in a (1 + 3)-dimensional space. Using homogeneous coordinates, we map that action on the unit sphere, which is at the realm of the Klein model of hyperbolic geometry. The effects of absorption appear then as a loxodromic transformation, that is, a rhumb line crossing all the meridians at the same angle.

  3. Multiphoton absorption in graphene and metal-organic frameworks

    NASA Astrophysics Data System (ADS)

    Weiqiang, Chen

    Materials possessing large multiphoton absorption are of direct relevance to both photonics applications and materials physics. In this dissertation, we present our investigations into two novel materials: namely, (1) graphene and (2) metal-organic frameworks (MOFs). The dissertation divides into two parts. The first part of the dissertation reports our systematical Z-scan measurements onto two-photon absorption (2PA) in graphene in the spectral range of 435-1100 nm with femtosecond laser pulses. We report that the measured 2PA coefficients of graphene in the near-infrared (NIR) range of 800-1100 nm can be explained by a theoretical model based on the optical transitions near the Dirac point (K point). We also determine the 2PA coefficients of graphene in the visible spectrum (435-700 nm) and observe an enhancement induced by the excitonic Fano resonance at the saddle point (M point). By applying the second-order, time-dependent perturbation theory on interband transitions among three states near the saddle point, we develop a semi-empirical model to take excitons in graphene into consideration. And the model is in agreement with the photon-energy dependence of the observed 2PA spectrum with a scaling factor of B = (1 5) x 102 cm/MW/eV5. Our results verify, for the first time, that the excitonic Fano resonance plays an important role for the 2PA of graphene in the visible spectrum. Besides, we also detail our measurements on the spectral dependence of one-photon absorption (1PA) saturation in graphene over the visible-NIR range. A quadratic photon energy dependence of the measured saturation intensity/fluence is observed over the investigated spectral range. The underlying photo-dynamics is discussed. In the second part of the dissertation, we investigate multiphoton excited photoluminescence (MEPL) from three solid-state crystals of metal-organic frameworks (MOFs): (1) [Zn2(trans,trans-4,4 stilbenedicarboxylic acid (SDC))2(trans, trans-9, 10-bis (4-pyridylethenyl

  4. Numerical approaches for predicting two-photon absorption induced single-event effects in semiconductors

    NASA Astrophysics Data System (ADS)

    Hales, Joel M.; Khachatrian, Ani; Roche, Nicolas J.; Buchner, Stephen; Warner, Jeffrey; McMorrow, Dale

    2016-05-01

    Two numerical approaches for determining the charge generated in semiconductors via two-photon absorption (2PA) under conditions relevant for laser-based single-event effects (SEE) experiments are presented. The first approach uses a simple analytical expression incorporating a small number of experimental/material parameters while the second approach employs a comprehensive beam propagation method that accounts for all the complex nonlinear optical (NLO) interactions present. The impact of the excitation conditions, device geometry, and specific NLO interactions on the resulting collected charge in silicon devices is also discussed. These approaches can provide value to the radiation-effects community by predicting the impacts that varying experimental parameters will have on 2PA SEE measurements.

  5. Creating semiconductor metafilms with designer absorption spectra

    PubMed Central

    Kim, Soo Jin; Fan, Pengyu; Kang, Ju-Hyung; Brongersma, Mark L.

    2015-01-01

    The optical properties of semiconductors are typically considered intrinsic and fixed. Here we leverage the rapid developments in the field of optical metamaterials to create ultrathin semiconductor metafilms with designer absorption spectra. We show how such metafilms can be constructed by placing one or more types of high-index semiconductor antennas into a dense array with subwavelength spacings. It is argued that the large absorption cross-section of semiconductor antennas and their weak near-field coupling open a unique opportunity to create strongly absorbing metafilms whose spectral absorption properties directly reflect those of the individual antennas. Using experiments and simulations, we demonstrate that near-unity absorption at one or more target wavelengths of interest can be achieved in a sub-50-nm-thick metafilm using judiciously sized and spaced Ge nanobeams. The ability to create semiconductor metafilms with custom absorption spectra opens up new design strategies for planar optoelectronic devices and solar cells. PMID:26184335

  6. XCOM: Photon Cross Sections Database

    National Institute of Standards and Technology Data Gateway

    SRD 8 XCOM: Photon Cross Sections Database (Web, free access)   A web database is provided which can be used to calculate photon cross sections for scattering, photoelectric absorption and pair production, as well as total attenuation coefficients, for any element, compound or mixture (Z <= 100) at energies from 1 keV to 100 GeV.

  7. First attempt to monitor atmospheric glyoxal using differential absorption lidar

    NASA Astrophysics Data System (ADS)

    Mei, Liang; Lundin, Patrik; Somesfalean, Gabriel; Hu, Jiandong; Zhao, Guangyu; Svanberg, Sune; Bood, Joakim; Vrekoussis, Mihalis; Papayannis, Alexandros

    2012-11-01

    Glyoxal (CHOCHO), as an indicator of photochemical "hot spots", was for the first time the subject of a differential absorption lidar (DIAL) campaign. The strongest absorption line of glyoxal in the blue wavelength region - 455.1 nm - was chosen as the experimental absorption wavelength. In order to handle the effects of absorption cross-section variation of the interfering gas - nitrogen dioxide (NO2) - three-wavelength DIAL measurements simultaneously detecting glyoxal and NO2, were performed. The differential absorption curves, recorded in July 2012, indicate an extremely low glyoxal concentration in Lund, Sweden, although it is expected to be peaking at this time of the year.

  8. Observation of the visible absorption spectrum of H2O(+)

    NASA Technical Reports Server (NTRS)

    Das, Biman; Farley, John W.

    1991-01-01

    The water cation, H2O(+), has been studied, using laser absorption spectroscopy in a velocity-modulated discharge. It is shown that it is possible to observe the absorption spectrum of an ion that is not a terminal ion, despite the weak absorption oscillator strength, and despite the use of a relatively noisy dye laser. The relative intensities of the absorption lines have been measured to an accuracy of 13 percent. It is concluded that if the absorption cross section of a single transition can be measured absolutely, then the entire manifold will be known absolutely.

  9. Atmospheric absorption cell characterization

    NASA Astrophysics Data System (ADS)

    1982-06-01

    The measurement capability of the Avionics Laboratory IR Facility was used to evaluate an absorption cell that will be used to simulate atmospheric absorption over horizontal paths of 1 - 10 km in length. Band models were used to characterize the transmittance of carbon dioxide (CO2), nitrogen (N2), and nitrous oxide (N2O) in the cell. The measured transmittance was compared to the calculated values. Nitrous oxide is important in the 4 - 4.5 micron range in shaping the weak line absorption of carbon dioxide. The absorption cell is adequate for simulating atmospheric absorption over these paths.

  10. The mid-IR Absorption Cross Sections of α- and β-NAT (HNO3 · 3H2O) in the range 170 to 185 K and of metastable NAD (HNO3 · 2H2O) in the range 172 to 182 K

    NASA Astrophysics Data System (ADS)

    Iannarelli, R.; Rossi, M. J.

    2015-11-01

    Growth and Fourier transform infrared (FTIR) absorption in transmission of the title nitric acid hydrates have been performed in a stirred flow reactor (SFR) under tight control of the H2O and HNO3 deposition conditions affording a closed mass balance of the binary mixture. The gas and condensed phases have been simultaneously monitored using residual gas mass spectrometry and FTIR absorption spectroscopy, respectively. Barrierless nucleation of the metastable phases of both α-NAT (nitric acid trihydrate) and NAD (nitric acid dihydrate) has been observed when HNO3 was admitted to the SFR in the presence of a macroscopic thin film of pure H2O ice of typically 1 µm thickness. The stable β-NAT phase was spontaneously formed from the precursor α-NAT phase through irreversible thermal rearrangement beginning at 185 K. This facile growth scheme of nitric acid hydrates requires the presence of H2O ice at thicknesses in excess of approximately hundred nanometers. Absolute absorption cross sections in the mid-IR spectral range (700-4000 cm-1) of all three title compounds have been obtained after spectral subtraction of excess pure ice at temperatures characteristic of the upper troposphere/lower stratosphere. Prominent IR absorption frequencies correspond to the antisymmetric nitrate stretch vibration (ν3(NO3-)) in the range 1300 to 1420 cm-1 and the bands of hydrated protons in the range 1670 to 1850 cm-1 in addition to the antisymmetric O-H stretch vibration of bound H2O in the range 3380 to 3430 cm-1 for NAT.

  11. The absolute absorption cross section of crystalline αg and βg HNO33H2O (NAT) and HNO32H2O (NAD) in the range 180 - 200 K in the mid-IR (4000 to 600 cm-1)

    NASA Astrophysics Data System (ADS)

    Rossi, Michel J.; Iannarelli, Riccardo

    2014-05-01

    Heterogeneous processing in the polar atmosphere requires the presence of polar stratospheric cloud particles (PSC's) that are the seat of interfacial chlorine and NOx chemistry. A subgroup of PSC's, namely PSC Ia, are known to consist of hydrates of nitric acid, mostly nitric acid trihydrate (NAT) as two polymorphs, α- and β-HNO33H2O occurring in the range 185 to 200 K under prevailing stratospheric partial pressure conditions of 10 ppb HNO3 or so. Despite the fact that reference IR spectra in the mid-IR range have been obtained some time ago (Ritzhaupt and Devlin (1991), Koehler et al. (1992)), no absolute absorption cross section of these important ice particles exist to date except a study of its refractive indices (Middlebrook et al. (1994), Berland et al. (1994)). Knowledge of optical cross sections would enable remote sensing of PSC's in the IR region using satellite and/or LIDAR platforms. We have embarked on a multidiagnostic research program aiming at studying the kinetics, thermodynamics and spectroscopy of PSC's using a stirred flow reactor equipped with FTIR absorption spectroscopy in transmission. The gas phase was monitored using electron-impact residual gas mass spectroscopy together with pulsed and steady-state gas admission and thorough characterization of the adsorption of HNO3, H2O and HCl onto the stainless-steel vessel walls under mass balance conditions using measured Langmuir adsorption isotherms. We have grown α- and β-NAT by doping thin (1 μm thick) ice films with metered amounts of HNO3. According to known phase diagrams we have obtained mixtures of pure ice with NAT whose IR spectrum was obtained after spectral subtraction of the pure ice phase. The concentration of HNO3 deposited on the ice film was determined by measuring the inflow and taking into account adsorption of HNO3 on the reactor walls as well as effusive loss out the reactor. We also independently checked the H2O concentration of α-NAT from the decrease of the pure H2O

  12. Solar absorption surface panel

    DOEpatents

    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.

  13. Rectal absorption of propylthiouracil.

    PubMed

    Bartle, W R; Walker, S E; Silverberg, J D

    1988-06-01

    The rectal absorption of propylthiouracil (PTU) was studied and compared to oral absorption in normal volunteers. Plasma levels of PTU after administration of suppositories of PTU base and PTU diethanolamine were significantly lower compared to the oral route. Elevated plasma reverse T3 levels were demonstrated after each treatment, however, suggesting a desirable therapeutic effect at this dosage level for all preparations.

  14. Petawatt laser absorption bounded

    PubMed Central

    Levy, Matthew C.; Wilks, Scott C.; Tabak, Max; Libby, Stephen B.; Baring, Matthew G.

    2014-01-01

    The interaction of petawatt (1015 W) lasers with solid matter forms the basis for advanced scientific applications such as table-top particle accelerators, ultrafast imaging systems and laser fusion. Key metrics for these applications relate to absorption, yet conditions in this regime are so nonlinear that it is often impossible to know the fraction of absorbed light f, and even the range of f is unknown. Here using a relativistic Rankine-Hugoniot-like analysis, we show for the first time that f exhibits a theoretical maximum and minimum. These bounds constrain nonlinear absorption mechanisms across the petawatt regime, forbidding high absorption values at low laser power and low absorption values at high laser power. For applications needing to circumvent the absorption bounds, these results will accelerate a shift from solid targets, towards structured and multilayer targets, and lead the development of new materials. PMID:24938656

  15. Bibliography of photoabsorption cross-section data

    NASA Technical Reports Server (NTRS)

    Hudson, R. D.; Kieffer, L. J.

    1970-01-01

    This bibliography contains only references which report a measured or calculated photoabsorption cross section (relative or normalized) in regions of continuous absorption. The bibliography is current as of January 1, 1970.

  16. Quasar Absorption Studies

    NASA Technical Reports Server (NTRS)

    Mushotzky, Richard (Technical Monitor); Elvis, Martin

    2004-01-01

    The aim of the proposal is to investigate the absorption properties of a sample of inter-mediate redshift quasars. The main goals of the project are: Measure the redshift and the column density of the X-ray absorbers; test the correlation between absorption and redshift suggested by ROSAT and ASCA data; constrain the absorber ionization status and metallicity; constrain the absorber dust content and composition through the comparison between the amount of X-ray absorption and optical dust extinction. Unanticipated low energy cut-offs where discovered in ROSAT spectra of quasars and confirmed by ASCA, BeppoSAX and Chandra. In most cases it was not possible to constrain adequately the redshift of the absorber from the X-ray data alone. Two possibilities remain open: a) absorption at the quasar redshift; and b) intervening absorption. The evidences in favour of intrinsic absorption are all indirect. Sensitive XMM observations can discriminate between these different scenarios. If the absorption is at the quasar redshift we can study whether the quasar environment evolves with the Cosmic time.

  17. Study of nonlinear optical absorption properties of Sb2Se3 nanoparticles in the nanosecond and femtosecond excitation regime

    NASA Astrophysics Data System (ADS)

    Molli, Muralikrishna; Pradhan, Prabin; Dutta, Devarun; Jayaraman, Aditya; Bhat Kademane, Abhijit; Muthukumar, V. Sai; Kamisetti, Venkataramaniah; Philip, Reji

    2016-05-01

    In this work, we report for the first time, the nonlinear optical absorption properties of antimony selenide (Sb2Se3) nanoparticles synthesized through solvothermal route. X-ray diffraction results revealed the crystalline nature of the nanoparticles. Electron microscopy studies revealed that the nanoparticles are in the range of 10-40 nm. Elemental analysis was performed using EDAX. The nanosecond optical limiting effect was characterized by using fluence-dependent transmittance measurements with 15-ns laser pulses at 532 and 1064 nm excitation wavelengths. Mechanistically, effective two-photon (2PA) absorption and nonlinear scattering processes were the dominant nonlinear processes at both the wavelengths. At 800 nm excitation in the femtosecond regime (100 fs), the nonlinear optical absorption was found to be a three-photon (3PA) process. Both 2PA and 3PA processes were explained using the band structure and density of states of Sb2Se3 obtained using density functional theory. These nanoparticles exhibit strong intensity-dependent nonlinear optical absorption and hence could be considered to have optical power-limiting applications in the visible range.

  18. Absorption heat pump system

    DOEpatents

    Grossman, G.

    1982-06-16

    The efficiency of an absorption heat pump system is improved by conducting liquid from a second stage evaporator thereof to an auxiliary heat exchanger positioned downstream of a primary heat exchanger in the desorber of the system.

  19. Compounds affecting cholesterol absorption

    NASA Technical Reports Server (NTRS)

    Hua, Duy H. (Inventor); Koo, Sung I. (Inventor); Noh, Sang K. (Inventor)

    2004-01-01

    A class of novel compounds is described for use in affecting lymphatic absorption of cholesterol. Compounds of particular interest are defined by Formula I: ##STR1## or a pharmaceutically acceptable salt thereof.

  20. Soliton absorption spectroscopy

    PubMed Central

    Kalashnikov, V. L.; Sorokin, E.

    2010-01-01

    We analyze optical soliton propagation in the presence of weak absorption lines with much narrower linewidths as compared to the soliton spectrum width using the novel perturbation analysis technique based on an integral representation in the spectral domain. The stable soliton acquires spectral modulation that follows the associated index of refraction of the absorber. The model can be applied to ordinary soliton propagation and to an absorber inside a passively modelocked laser. In the latter case, a comparison with water vapor absorption in a femtosecond Cr:ZnSe laser yields a very good agreement with experiment. Compared to the conventional absorption measurement in a cell of the same length, the signal is increased by an order of magnitude. The obtained analytical expressions allow further improving of the sensitivity and spectroscopic accuracy making the soliton absorption spectroscopy a promising novel measurement technique. PMID:21151755

  1. Absorption heat pump system

    DOEpatents

    Grossman, Gershon

    1984-01-01

    The efficiency of an absorption heat pump system is improved by conducting liquid from a second stage evaporator thereof to an auxiliary heat exchanger positioned downstream of a primary heat exchanger in the desorber of the system.

  2. Excited-state absorption of Tm3 + -doped single crystals at photon-avalanche wavelengths

    NASA Astrophysics Data System (ADS)

    Garnier, N.; Moncorgé, R.; Manaa, H.; Descroix, E.; Laporte, P.; Guyot, Y.

    1996-04-01

    Excited-state absorption (ESA) spectra calibrated in units of cross sections are reported in the case of Tm3+-doped YAG, YAP, and Y2O3 single crystals around wavelengths at which photon-avalanche absorptions were observed recently. The peak ESA cross sections are compared with those obtained theoretically by using the Judd-Ofelt approach.

  3. Microwave spectrometer for saturated absorption experiments.

    PubMed

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

    1978-04-01

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

  4. Optical absorption measurement system

    DOEpatents

    Draggoo, Vaughn G.; Morton, Richard G.; Sawicki, Richard H.; Bissinger, Horst D.

    1989-01-01

    The system of the present invention contemplates a non-intrusive method for measuring the temperature rise of optical elements under high laser power optical loading to determine the absorption coefficient. The method comprises irradiating the optical element with a high average power laser beam, viewing the optical element with an infrared camera to determine the temperature across the optical element and calculating the absorption of the optical element from the temperature.

  5. Solar selective absorption coatings

    DOEpatents

    Mahoney, Alan R.; Reed, Scott T.; Ashley, Carol S.; Martinez, F. Edward

    2003-10-14

    A new class of solar selective absorption coatings are disclosed. These coatings comprise a structured metallic overlayer such that the overlayer has a sub-micron structure designed to efficiently absorb solar radiation, while retaining low thermal emissivity for infrared thermal radiation. A sol-gel layer protects the structured metallic overlayer from mechanical, thermal, and environmental degradation. Processes for producing such solar selective absorption coatings are also disclosed.

  6. Solar selective absorption coatings

    DOEpatents

    Mahoney, Alan R.; Reed, Scott T.; Ashley, Carol S.; Martinez, F. Edward

    2004-08-31

    A new class of solar selective absorption coatings are disclosed. These coatings comprise a structured metallic overlayer such that the overlayer has a sub-micron structure designed to efficiently absorb solar radiation, while retaining low thermal emissivity for infrared thermal radiation. A sol-gel layer protects the structured metallic overlayer from mechanical, thermal, and environmental degradation. Processes for producing such solar selective absorption coatings are also disclosed.

  7. Intranasal absorption of oxymorphone.

    PubMed

    Hussain, M A; Aungst, B J

    1997-08-01

    The nasal bioavailability of oxymorphone HCI was determined. Rats were surgically prepared to isolate the nasal cavity, into which a solution of oxymorphone was administered. A reference group of rats was administered oxymorphone HCl intravenously. Plasma oxymorphone concentrations were determined by HPLC. Nasal absorption was rapid, nasal bioavailability was 43%, and the iv and nasal elimination profiles were similar. Oxymorphone HCI appears to have the solubility, potency, and absorption properties required for efficient nasal delivery, which is an alternative to injections.

  8. Seven-effect absorption refrigeration

    DOEpatents

    DeVault, R.C.; Biermann, W.J.

    1989-05-09

    A seven-effect absorption refrigeration cycle is disclosed utilizing three absorption circuits. In addition, a heat exchanger is used for heating the generator of the low absorption circuit with heat rejected from the condenser and absorber of the medium absorption circuit. A heat exchanger is also provided for heating the generator of the medium absorption circuit with heat rejected from the condenser and absorber of the high absorption circuit. If desired, another heat exchanger can also be provided for heating the evaporator of the high absorption circuit with rejected heat from either the condenser or absorber of the low absorption circuit. 1 fig.

  9. Seven-effect absorption refrigeration

    DOEpatents

    DeVault, Robert C.; Biermann, Wendell J.

    1989-01-01

    A seven-effect absorption refrigeration cycle is disclosed utilizing three absorption circuits. In addition, a heat exchanger is used for heating the generator of the low absorption circuit with heat rejected from the condenser and absorber of the medium absorption circuit. A heat exchanger is also provided for heating the generator of the medium absorption circuit with heat rejected from the condenser and absorber of the high absorption circuit. If desired, another heat exchanger can also be provided for heating the evaporator of the high absorption circuit with rejected heat from either the condenser or absorber of the low absorption circuit.

  10. Horizontal Cross Bracing Detail, Vertical Cross Bracing Detail, Horizontal Cross ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Horizontal Cross Bracing Detail, Vertical Cross Bracing Detail, Horizontal Cross Bracing Detail, Vertical Cross Bracing-End Detail - Cumberland Covered Bridge, Spanning Mississinewa River, Matthews, Grant County, IN

  11. Absorption heat pump system

    DOEpatents

    Grossman, Gershon; Perez-Blanco, Horacio

    1984-01-01

    An improvement in an absorption heat pump cycle is obtained by adding adiabatic absorption and desorption steps to the absorber and desorber of the system. The adiabatic processes make it possible to obtain the highest temperature in the absorber before any heat is removed from it and the lowest temperature in the desorber before heat is added to it, allowing for efficient utilization of the thermodynamic availability of the heat supply stream. The improved system can operate with a larger difference between high and low working fluid concentrations, less circulation losses, and more efficient heat exchange than a conventional system.

  12. Absorption Heat Pump Cycles

    NASA Astrophysics Data System (ADS)

    Kunugi, Yoshifumi; Kashiwagi, Takao

    Various advanced absorption cycles are studied, developed and invented. In this paper, their cycles are classified and arranged using the three categories: effect, stage and loop, then an outline of the cycles are explained on the Duehring diagram. Their cycles include high COP cycles for refrigerations and heat pumps, high temperature lift cycles for heat transformer, absorption-compression hybrid cycles and heat pump transformer cycle. The highest COPi is attained by the seven effect cycle. In addition, the cycles for low temperature are invented and explained. Furthermore the power generation • refrigeration cycles are illustrated.

  13. Optical absorption spectra of palladium doped gold cluster cations

    SciTech Connect

    Kaydashev, Vladimir E.; Janssens, Ewald Lievens, Peter

    2015-01-21

    Photoabsorption spectra of gas phase Au{sub n}{sup +} and Au{sub n−1}Pd{sup +} (13 ≤ n ≤ 20) clusters were measured using mass spectrometric recording of wavelength dependent Xe messenger atom photodetachment in the 1.9–3.4 eV photon energy range. Pure cationic gold clusters consisting of 15, 17, and 20 atoms have a higher integrated optical absorption cross section than the neighboring sizes. It is shown that the total optical absorption cross section increases with size and that palladium doping strongly reduces this cross section for all investigated sizes and in particular for n = 14–17 and 20. The largest reduction of optical absorption upon Pd doping is observed for n = 15.

  14. Ultraviolet absorption spectrum of hydrogen peroxide vapor. [for atmospheric abundances

    NASA Technical Reports Server (NTRS)

    Molina, L. T.; Schinke, S. D.; Molina, M. J.

    1977-01-01

    The ultraviolet absorption cross sections of hydrogen peroxide vapor have been determined over the wavelength range 210 to 350 nm at 296 K. At the longer wavelengths, the gas phase absorptivities are significantly larger than the corresponding values in condensed phase. The atmospheric H2O2 photodissociation rate for overhead sun at the earth's surface is estimated to be about 1.3 x 10 to the -5th/sec.

  15. Two-Phonon Absorption

    ERIC Educational Resources Information Center

    Hamilton, M. W.

    2007-01-01

    A nonlinear aspect of the acousto-optic interaction that is analogous to multi-photon absorption is discussed. An experiment is described in which the second-order acousto-optically scattered intensity is measured and found to scale with the square of the acoustic intensity. This experiment using a commercially available acousto-optic modulator is…

  16. Towards quantitative atmospheric water vapor profiling with differential absorption lidar.

    PubMed

    Dinovitser, Alex; Gunn, Lachlan J; Abbott, Derek

    2015-08-24

    Differential Absorption Lidar (DIAL) is a powerful laser-based technique for trace gas profiling of the atmosphere. However, this technique is still under active development requiring precise and accurate wavelength stabilization, as well as accurate spectroscopic parameters of the specific resonance line and the effective absorption cross-section of the system. In this paper we describe a novel master laser system that extends our previous work for robust stabilization to virtually any number of multiple side-line laser wavelengths for the future probing to greater altitudes. In this paper, we also highlight the significance of laser spectral purity on DIAL accuracy, and illustrate a simple re-arrangement of a system for measuring effective absorption cross-section. We present a calibration technique where the laser light is guided to an absorption cell with 33 m path length, and a quantitative number density measurement is then used to obtain the effective absorption cross-section. The same absorption cell is then used for on-line laser stabilization, while microwave beat-frequencies are used to stabilize any number of off-line lasers. We present preliminary results using ∼300 nJ, 1 μs pulses at 3 kHz, with the seed laser operating as a nanojoule transmitter at 822.922 nm, and a receiver consisting of a photomultiplier tube (PMT) coupled to a 356 mm mirror.

  17. 69. INTERIOR VIEW OF THE ABSORPTION TOWER BUILDING, ABSORPTION TOWER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    69. INTERIOR VIEW OF THE ABSORPTION TOWER BUILDING, ABSORPTION TOWER UNDER CONSTRUCTION. (DATE UNKNOWN). - United States Nitrate Plant No. 2, Reservation Road, Muscle Shoals, Muscle Shoals, Colbert County, AL

  18. Quantum absorption refrigerator.

    PubMed

    Levy, Amikam; Kosloff, Ronnie

    2012-02-17

    A quantum absorption refrigerator driven by noise is studied with the purpose of determining the limitations of cooling to absolute zero. The model consists of a working medium coupled simultaneously to hot, cold, and noise baths. Explicit expressions for the cooling power are obtained for Gaussian and Poisson white noise. The quantum model is consistent with the first and second laws of thermodynamics. The third law is quantified; the cooling power J(c) vanishes as J(c) ∝ T(c)(α), when T(c)→0, where α=d+1 for dissipation by emission and absorption of quanta described by a linear coupling to a thermal bosonic field, where d is the dimension of the bath.

  19. Acoustic absorption by sunspots

    NASA Technical Reports Server (NTRS)

    Braun, D. C.; Labonte, B. J.; Duvall, T. L., Jr.

    1987-01-01

    The paper presents the initial results of a series of observations designed to probe the nature of sunspots by detecting their influence on high-degree p-mode oscillations in the surrounding photosphere. The analysis decomposes the observed oscillations into radially propagating waves described by Hankel functions in a cylindrical coordinate system centered on the sunspot. From measurements of the differences in power between waves traveling outward and inward, it is demonstrated that sunspots appear to absorb as much as 50 percent of the incoming acoustic waves. It is found that for all three sunspots observed, the amount of absorption increases linearly with horizontal wavenumber. The effect is present in p-mode oscillations with wavelengths both significantly larger and smaller than the diameter of the sunspot umbrae. Actual absorption of acoustic energy of the magnitude observed may produce measurable decreases in the power and lifetimes of high-degree p-mode oscillations during periods of high solar activity.

  20. Absorption of infrared radiation by electrons in the field of a neutral hydrogen atom

    NASA Technical Reports Server (NTRS)

    Stallcop, J. R.

    1974-01-01

    An analytical expression for the absorption coefficient is developed from a relationship between the cross-section for inverse bremsstrahlung absorption and the cross-section for electron-atom momentum transfer; it is accurate for those photon frequencies v and temperatures such that hv/kT is small. The determination of the absorption of infrared radiation by free-free transitions of the negative hydrogen ion has been extended to higher temperatures. A simple analytical expression for the absorption coefficient has been derived.

  1. Direct measurements of nonlinear absorption and refraction in solutions of phthalocyanines

    NASA Technical Reports Server (NTRS)

    Wei, T. H.; Hagan, D. J.; Sence, M. J.; Van Stryland, E. W.; Perry, J. W.; Coulter, D. R.

    1992-01-01

    Direct measurements are reported of the excited singlet-state absorption cross section and the associated nonlinear refractive cross section using picosecond pulses at 532 nm in solutions of phthalocyanine and naphthalocyanine dyes. By monitoring the transmittance and far-field spatial beam distortion for different pulsewidths in the picosecond regime, it is shown that both the nonlinear absorption and refraction are fluence (energy-per-unit-area) rather than irradiance dependent. Thus, excited-state absorption is the dominant nonlinear absorption process, and the observed nonlinear refraction is also due to real population excitation.

  2. Bioacoustic Absorption Spectroscopy

    DTIC Science & Technology

    2016-06-07

    seas in co-operation with fisheries biologists. The first planned experiment will be in the seas off California in co-operation with the Southwest... Fisheries Science Center of NOAA’s National Marine Fisheries Service. These experiments will be designed to investigate the “signatures” of the two major...formulating environmental adaptation strategies for tactical sonars. Fisheries applications: These results suggest that bioacoustic absorptivity can be used to

  3. Vehicular impact absorption system

    NASA Technical Reports Server (NTRS)

    Knoell, A. C.; Wilson, A. H. (Inventor)

    1978-01-01

    An improved vehicular impact absorption system characterized by a plurality of aligned crash cushions of substantially cubic configuration is described. Each consists of a plurality of voided aluminum beverage cans arranged in substantial parallelism within a plurality of superimposed tiers and a covering envelope formed of metal hardware cloth. A plurality of cables is extended through the cushions in substantial parallelism with an axis of alignment for the cushions adapted to be anchored at each of the opposite end thereof.

  4. Hydrogen Absorption by Niobium.

    DTIC Science & Technology

    1982-04-13

    incorporate an independent means for ascertaining surface cleanliness (e.g. AES). The form of the absorption curve in Fig. 7 appears to agree with that...very interesting study and is well within the capabilities of the systen designed, if the surface cleanliness can be assured. Wire specimens have a...assessing surface cleanliness would be an important supporting technique for understanding the results of these measurements. The simple kinetic

  5. Relic Neutrino Absorption Spectroscopy

    SciTech Connect

    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.

  6. Detection of water vapour absorption around 363nm in measured atmospheric absorption spectra and its effect on DOAS evaluations

    NASA Astrophysics Data System (ADS)

    Lampel, Johannes; Polyansky, Oleg. L.; Kyuberis, Alexandra A.; Zobov, Nikolai F.; Tennyson, Jonathan; Lodi, Lorenzo; Pöhler, Denis; Frieß, Udo; Platt, Ulrich; Beirle, Steffen; Wagner, Thomas

    2016-04-01

    Water vapour is known to absorb light from the microwave region to the blue part of the visible spectrum at a decreasing magnitude. Ab-initio approaches to model individual absorption lines of the gaseous water molecule predict absorption lines until its dissociation limit at 243 nm. We present first evidence of water vapour absorption at 363 nm from field measurements based on the POKAZATEL absorption line list by Polyansky et al. (2016) using data from Multi-Axis differential optical absorption spectroscopy (MAX-DOAS) and Longpath (LP)-DOAS measurements. The predicted absorptions contribute significantly to the observed optical depths with up to 2 × 10-3. Their magnitude correlates well (R2 = 0.89) to simultaneously measured well-established water vapour absorptions in the blue spectral range from 452-499 nm, but is underestimated by a factor of 2.6 ± 0.6 in the ab-initio model. At a spectral resolution of 0.5nm this leads to a maximum absorption cross-section value of 5.4 × 10-27 cm2/molec at 362.3nm. The results are independent of the employed cross-section data to compensate for the overlayed absorption of the oxygen dimer O4. The newly found absorption can have a significant impact on the spectral retrieval of absorbing trace-gas species in the spectral range around 363 nm. Its effect on the spectral analysis of O4, HONO and OClO are discussed.

  7. Ultrahigh resolution photoacoustic microscopy via transient absorption

    PubMed Central

    Shelton, Ryan L.; Applegate, Brian E.

    2010-01-01

    We have developed a novel, hybrid imaging modality, Transient Absorption Ultrasonic Microscopy (TAUM), which takes advantage of the optical nonlinearities afforded by transient absorption to achieve ultrahigh-resolution photoacoustic microscopy. The theoretical point spread function for TAUM is functionally equivalent to confocal and two-photon fluorescence microscopy, potentially enabling cellular/subcellular photoacoustic imaging. A prototype TAUM system was designed, built, and used to image a cross-section through several capillaries in the excised cheek pouch of a Syrian Hamster. The well-resolved capillaries in the TAUM image provided experimental evidence of the spatial resolution. These results suggest that TAUM has excellent potential for producing volumetric images with cellular/subcellular resolution in three dimensions deep inside living tissue. PMID:21258499

  8. Ultraviolet Absorption by Secondary Organic Aerosols

    NASA Astrophysics Data System (ADS)

    Madronich, S.; Lee-Taylor, J. M.; Hodzic, A.; Aumont, B.

    2014-12-01

    Secondary organic aerosols (SOA) are typically formed in the atmosphere by the condensation of a myriad of intermediates from the photo-oxidation of volatile organic compounds (VOCs). Many of these partly oxidized molecules have functional groups (chromophores) that absorb at the ultraviolet (UV) wavelengths available in the troposphere (λ ≳ 290 nm). We used the explicit chemical model GECKO-A (Generator of Explicit Chemistry and Kinetics for Organics in the Atmosphere) to estimate UV absorption cross sections for the gaseous and particulate components of SOA from different precursors (biogenic and anthropogenic) and formed in different environments (low and high NOx, day and night). Model predictions are evaluated with laboratory and field measurements of SOA UV optical properties (esp. mass absorption coefficients and single scattering albedo), and implications are presented for surface UV radiation trends, urban actinic flux modification, and SOA lifetimes.

  9. Absorption of a Massive Scalar Field by Wormhole Space-Times

    NASA Astrophysics Data System (ADS)

    Huang, Hai; Chen, Juhua; Wang, Yongjiu; Jin, Yao

    2017-04-01

    In this paper we consider the problem of the test massive scalar field propagating in the background of a class of wormhole space-times. Basing on the quantum scattering theory, we analyze the Schrödinger-type scalar wave equation and compute transmission coefficients for arbitrary coupling of the field to the background geometry with the WKB approximation. We numerically investigate its absorption cross section and analyze them in the high frequency regime. We find that the absorption cross section oscillates about the geometric optical value and the limit of absorption cross section is uniform in the high frequency regime.

  10. Absorption of a Massive Scalar Field by Wormhole Space-Times

    NASA Astrophysics Data System (ADS)

    Huang, Hai; Chen, Juhua; Wang, Yongjiu; Jin, Yao

    2017-01-01

    In this paper we consider the problem of the test massive scalar field propagating in the background of a class of wormhole space-times. Basing on the quantum scattering theory, we analyze the Schrödinger-type scalar wave equation and compute transmission coefficients for arbitrary coupling of the field to the background geometry with the WKB approximation. We numerically investigate its absorption cross section and analyze them in the high frequency regime. We find that the absorption cross section oscillates about the geometric optical value and the limit of absorption cross section is uniform in the high frequency regime.

  11. Corrosion Problems in Absorption Chillers

    ERIC Educational Resources Information Center

    Stetson, Bruce

    1978-01-01

    Absorption chillers use a lithium bromide solution as the medium of absorption and water as the refrigerant. Discussed are corrosion and related problems, tests and remedies, and cleaning procedures. (Author/MLF)

  12. Temperature dependence of the excited state absorption of alexandrite

    SciTech Connect

    Shand, M.L.; Jenssen, H.P.

    1983-03-01

    The temperature dependence from 28 to 290/sup 0/C of the excited-state absorption cross section sigma /SUB 2a/ (E) in the gain wavelength region of alexandrite has been determined from the temperature dependence of the single pass gain (SPG) and of the fluorescence. sigma /SUB 2a/ (E) and the emission cross section increase with temperature at approximately the same rate.

  13. Horizontal Cross Bracing Detail, Vertical Cross Bracing Detail, Horizontal Cross ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Horizontal Cross Bracing Detail, Vertical Cross Bracing Detail, Horizontal Cross Bracing Joint, Vertical Cross Bracing End Detail - Ceylon Covered Bridge, Limberlost Park, spanning Wabash River at County Road 900 South, Geneva, Adams County, IN

  14. Acoustic Absorption Characteristics of People.

    ERIC Educational Resources Information Center

    Kingsbury, H. F.; Wallace, W. J.

    1968-01-01

    The acoustic absorption characteristics of informally dressed college students in typical classroom seating are shown to differ substantially from data for formally dressed audiences in upholstered seating. Absorption data, expressed as sabins per person or absorption coefficient per square foot, shows that there is considerable variation between…

  15. Quantum Entanglement Molecular Absorption Spectrum Simulator

    NASA Technical Reports Server (NTRS)

    Nguyen, Quang-Viet; Kojima, Jun

    2006-01-01

    Quantum Entanglement Molecular Absorption Spectrum Simulator (QE-MASS) is a computer program for simulating two photon molecular-absorption spectroscopy using quantum-entangled photons. More specifically, QE-MASS simulates the molecular absorption of two quantum-entangled photons generated by the spontaneous parametric down-conversion (SPDC) of a fixed-frequency photon from a laser. The two-photon absorption process is modeled via a combination of rovibrational and electronic single-photon transitions, using a wave-function formalism. A two-photon absorption cross section as a function of the entanglement delay time between the two photons is computed, then subjected to a fast Fourier transform to produce an energy spectrum. The program then detects peaks in the Fourier spectrum and displays the energy levels of very short-lived intermediate quantum states (or virtual states) of the molecule. Such virtual states were only previously accessible using ultra-fast (femtosecond) laser systems. However, with the use of a single-frequency continuous wave laser to produce SPDC photons, and QEMASS program, these short-lived molecular states can now be studied using much simpler laser systems. QE-MASS can also show the dependence of the Fourier spectrum on the tuning range of the entanglement time of any externally introduced optical-path delay time. QE-MASS can be extended to any molecule for which an appropriate spectroscopic database is available. It is a means of performing an a priori parametric analysis of entangled photon spectroscopy for development and implementation of emerging quantum-spectroscopic sensing techniques. QE-MASS is currently implemented using the Mathcad software package.

  16. Ultraviolet absorption hygrometer

    DOEpatents

    Gersh, Michael E.; Bien, Fritz; Bernstein, Lawrence S.

    1986-01-01

    An ultraviolet absorption hygrometer is provided including a source of pulsed ultraviolet radiation for providing radiation in a first wavelength region where water absorbs significantly and in a second proximate wavelength region where water absorbs weakly. Ultraviolet radiation in the first and second regions which has been transmitted through a sample path of atmosphere is detected. The intensity of the radiation transmitted in each of the first and second regions is compared and from this comparison the amount of water in the sample path is determined.

  17. Ultraviolet absorption hygrometer

    DOEpatents

    Gersh, M.E.; Bien, F.; Bernstein, L.S.

    1986-12-09

    An ultraviolet absorption hygrometer is provided including a source of pulsed ultraviolet radiation for providing radiation in a first wavelength region where water absorbs significantly and in a second proximate wavelength region where water absorbs weakly. Ultraviolet radiation in the first and second regions which has been transmitted through a sample path of atmosphere is detected. The intensity of the radiation transmitted in each of the first and second regions is compared and from this comparison the amount of water in the sample path is determined. 5 figs.

  18. Modular total absorption spectrometer

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

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

  19. Ultraviolet absorption spectrum of methylhydroperoxide vapor. [in troposphere

    NASA Technical Reports Server (NTRS)

    Molina, M. J.; Arguello, G.

    1979-01-01

    The ultraviolet absorption cross sections of methylhydroperoxide, CH3OOH, have been measured over the wavelength range 210 nm to 350 nm at 294 K. It was concluded that solar photolysis is a dominant sink for tropospheric CH3OOH. For midlatitudes the photodissociation rate was estimated for 0 deg, for 30 deg, and for 70 deg zenith angles.

  20. The HI absorption "Zoo"

    NASA Astrophysics Data System (ADS)

    Geréb, K.; Maccagni, F. M.; Morganti, R.; Oosterloo, T. A.

    2015-03-01

    We present an analysis of the H I 21 cm absorption in a sample of 101 flux-selected radio AGN (S1.4 GHz> 50 mJy) observed with the Westerbork Synthesis Radio Telescope (WSRT). We detect H I absorption in 32 objects (30% of the sample). In a previous paper, we performed a spectral stacking analysis on the radio sources, while here we characterize the absorption spectra of the individual detections using the recently presented busy function. The H I absorption spectra show a broad variety of widths, shapes, and kinematical properties. The full width half maximum (FWHM) of the busy function fits of the detected H I lines lies in the range 32 km s-1absorption (FW20) lies in the range 63 km s-1 200 km s-1). We study the kinematical and radio source properties of each group, with the goal of identifying different morphological structures of H I. Narrow lines mostly lie at the systemic velocity and are likely produced by regularly rotating H I disks or gas clouds. More H I disks can be present among galaxies with lines of intermediate widths; however, the H I in these sources is more unsettled. We study the asymmetry parameter and blueshift/redshift distribution of the lines as a function of their width. We find a trend for which narrow profiles are also symmetric, while broad lines are the most asymmetric. Among the broadest lines, more lines appear blueshifted than redshifted, similarly to what was found by previous studies. Interestingly, symmetric broad lines are absent from the sample. We argue that if a profile is broad, it is also asymmetric and shifted relative to the systemic velocity because it is tracing unsettled H I gas. In particular, besides three of the broadest (up to FW20 = 825 km s-1

  1. Analyzing Water's Optical Absorption

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A cooperative agreement between World Precision Instruments (WPI), Inc., and Stennis Space Center has led the UltraPath(TM) device, which provides a more efficient method for analyzing the optical absorption of water samples at sea. UltraPath is a unique, high-performance absorbance spectrophotometer with user-selectable light path lengths. It is an ideal tool for any study requiring precise and highly sensitive spectroscopic determination of analytes, either in the laboratory or the field. As a low-cost, rugged, and portable system capable of high- sensitivity measurements in widely divergent waters, UltraPath will help scientists examine the role that coastal ocean environments play in the global carbon cycle. UltraPath(TM) is a trademark of World Precision Instruments, Inc. LWCC(TM) is a trademark of World Precision Instruments, Inc.

  2. Differential optoacoustic absorption detector

    NASA Technical Reports Server (NTRS)

    Shumate, M. S. (Inventor)

    1978-01-01

    A differential optoacoustic absorption detector employed two tapered cells in tandem or in parallel. When operated in tandem, two mirrors were used at one end remote from the source of the beam of light directed into one cell back through the other, and a lens to focus the light beam into the one cell at a principal focus half way between the reflecting mirror. Each cell was tapered to conform to the shape of the beam so that the volume of one was the same as for the other, and the volume of each received maximum illumination. The axes of the cells were placed as close to each other as possible in order to connect a differential pressure detector to the cells with connecting passages of minimum length. An alternative arrangement employed a beam splitter and two lenses to operate the cells in parallel.

  3. Two absorption furosemide prodrugs.

    PubMed

    Mombrú, A W; Mariezcurrena, R A; Suescun, L; Pardo, H; Manta, E; Prandi, C

    1999-03-15

    The structures of two absorption furosemide prodrugs, hexanoyloxymethyl 4-chloro-N-furfuryl-5-sulfamoyl-anthranilate (C19H23CIN2O7S), (I), and benzoyloxymethyl 4-chloro-N-furfuryl-5-sulfamoylanthranilate (C20H17CIN2O7S), (II), are described in this paper and compared with furosemide and four other prodrugs. The molecular conformations of both compounds are similar to those of the other prodrugs; the packing and the crystal system are the primary differences. Compound (I) crystallizes in the trigonal space group R3 and compound (II) in the monoclinic space group P2(1)/n. The packing of both structures is stabilized by a three-dimensional hydrogen-bond network.

  4. Excited singlet-state absorption in laser dyes at the XeCl wavelength

    NASA Astrophysics Data System (ADS)

    Taylor, R. S.; Mihailov, S.

    1985-10-01

    The transmission properties of the laser dyes BBQ, PBD, BPBD, α-NPO, p-Quarterphenyl and PPO have been measured using a XeCl (308 nm) excimer laser. A model for the dye saturation which incorporates excited-state absorption was used to estimate the lifetime and the absorption cross section of the first excited singlet-state for each dye.

  5. Accurate Cross Sections for Microanalysis

    PubMed Central

    Rez, Peter

    2002-01-01

    To calculate the intensity of x-ray emission in electron beam microanalysis requires a knowledge of the energy distribution of the electrons in the solid, the energy variation of the ionization cross section of the relevant subshell, the fraction of ionizations events producing x rays of interest and the absorption coefficient of the x rays on the path to the detector. The theoretical predictions and experimental data available for ionization cross sections are limited mainly to K shells of a few elements. Results of systematic plane wave Born approximation calculations with exchange for K, L, and M shell ionization cross sections over the range of electron energies used in microanalysis are presented. Comparisons are made with experimental measurement for selected K shells and it is shown that the plane wave theory is not appropriate for overvoltages less than 2.5 V. PMID:27446747

  6. X-ray Absorption Spectroscopy

    SciTech Connect

    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.

  7. BASIC STUDIES IN PERCUTANEOUS ABSORPTION.

    DTIC Science & Technology

    FATTY ACIDS, *SKIN(ANATOMY), ABSORPTION, ALKYL RADICALS, AMIDES, DIFFUSION, ELECTRON MICROSCOPY, HUMIDITY, LABORATORY ANIMALS, LIPIDS, ORGANIC SOLVENTS, PENETRATION, PRIVATION, PROTEINS, RATS, TEMPERATURE, WATER

  8. MMT Survey for Intervening Mg II Absorption

    NASA Astrophysics Data System (ADS)

    Nestor, Daniel B.; Turnshek, David A.; Rao, Sandhya M.

    2006-05-01

    We present the results from a spectroscopic survey for intervening Mg II absorption in the spectra of 381 background QSOs conducted at the MMT telescope. This survey complements our earlier SDSS EDR Mg II survey, extending our results to lower redshift (z~=0.15) and weaker Mg II λ2796 rest equivalent width (Wλ27960~=0.1 Å). We confirm two major results from that survey: the transition in the Wλ27960 distribution at Wλ27960~0.3 Å, and the Wλ27960-dependent evolution of the incidence of systems. The nature of ∂2N/∂z∂Wλ27960 is consistent with the idea that multiple physically distinct components/processes contribute to the incidence of Mg II absorption systems in a W0-dependent manner and evolve at different rates. A significant decrease in the total proper absorption cross section is detected in our MMT data for systems as weak as 1.0 Å<=Wλ27960<1.5 Å at z<~0.4. We discuss this W0-dependent evolution in the context of the evolution of galaxy structures, processes including superwinds and interactions, and damped-Lyα absorbers. We also consider the possibility that the observed redshift and Wλ27960 dependence of the incidence of absorption in spectroscopic surveys for low-ionization/neutral gas results from the effects of dust-induced extinction. Observations reported here were obtained at the MMT Observatory, a joint facility of the Smithsonian Institution and the University of Arizona.

  9. Solar Absorption in Cloudy Atmospheres

    NASA Technical Reports Server (NTRS)

    Harshvardhan; Ridgway, William; Ramaswamy, V.; Freidenreich, S. M.; Batey, Michael

    1996-01-01

    The theoretical computations used to compute spectral absorption of solar radiation are discussed. Radiative properties relevant to the cloud absorption problem are presented and placed in the context of radiative forcing. Implications for future measuring programs and the effect of horizontal inhomogeneities are discussed.

  10. Atmospheric absorption of sound - Update

    NASA Technical Reports Server (NTRS)

    Bass, H. E.; Sutherland, L. C.; Zuckerwar, A. J.

    1990-01-01

    Best current expressions for the vibrational relaxation times of oxygen and nitrogen in the atmosphere are used to compute total absorption. The resulting graphs of total absorption as a function of frequency for different humidities should be used in lieu of the graph published earlier by Evans et al (1972).

  11. Subgap Absorption in Conjugated Polymers

    DOE R&D Accomplishments Database

    Sinclair, M.; Seager, C. H.; McBranch, D.; Heeger, A. J; Baker, G. L.

    1991-01-01

    Along with X{sup (3)}, the magnitude of the optical absorption in the transparent window below the principal absorption edge is an important parameter which will ultimately determine the utility of conjugated polymers in active integrated optical devices. With an absorptance sensitivity of < 10{sup {minus}5}, Photothermal Deflection Spectroscopy (PDS) is ideal for determining the absorption coefficients of thin films of transparent'' materials. We have used PDS to measure the optical absorption spectra of the conjugated polymers poly(1,4-phenylene-vinylene) (and derivitives) and polydiacetylene-4BCMU in the spectral region from 0.55 eV to 3 eV. Our spectra show that the shape of the absorption edge varies considerably from polymer to polymer, with polydiacetylene-4BCMU having the steepest absorption edge. The minimum absorption coefficients measured varied somewhat with sample age and quality, but were typically in the range 1 cm{sup {minus}1} to 10 cm{sup {minus}1}. In the region below 1 eV, overtones of C-H stretching modes were observed, indicating that further improvements in transparency in this spectral region might be achieved via deuteration of fluorination.

  12. Chemical dynamics and reverse saturable absorption in di-furfuryl ether solutions

    NASA Astrophysics Data System (ADS)

    Mendonça, C. R.; Batista, P. S.; de Souza, M. F.; Zilio, S. C.

    2001-08-01

    We report on the chemical dynamics and nonlinear optical absorption of di-furfuryl ether (DFE) solutions. DFE molecules were derivatized from the room temperature furfuryl alcohol self-reaction, whose reaction kinetics was investigated with the Z-scan technique and laser-induced fluorescence. These molecules are shown to exhibit a pronounced reverse saturable absorption process. The magnitude of the excited-state absorption cross-sections and the intersystem crossing lifetime have been evaluated with 8 ns pulses at 532 nm.

  13. Temperature dependence of the NO3 absorption spectrum

    NASA Technical Reports Server (NTRS)

    Sander, Stanley P.

    1986-01-01

    The absorption spectrum of the gas-phase NO3 radical has been studied between 220 and 700 nm by using both flash photolysis and discharge flow reactors for the production of NO3. In the flash photolysis method, cross sections at the peak of the (0,0) band at 661.9 nm were measured relative to the cross section of ClONO2 at several different wavelengths. From the best current measurements of the ClONO2 spectrum, the NO3 cross section at 661.9 nm was determined to be (2.28 + or 0.34) x 10 to the -17th sq cm/molecule at 298 K. Measurements at 230 K indicated that the cross section increases by a factor of 1.18 at the peak of the (0,0) band. The discharge flow method was used both to obtain absolute cross sections at 661.9 nm and to obtain relative absorption spectra between 300 and 700 nm at 298 and 230 K. A value of (1.83 + or - 0.27) x 10 to the -17th sq cm/molecule was obtained for sigma NO3 at 661.9 nm at 298 K. Upper limits to the NO3 cross sections were also measured between 220 and 260 nm with the discharge flow method.

  14. Optical absorption of silicon nanowires

    SciTech Connect

    Xu, T.; Lambert, Y.; Krzeminski, C.; Grandidier, B.; Stievenard, D.; Leveque, G.; Akjouj, A.; Pennec, Y.; Djafari-Rouhani, B.

    2012-08-01

    We report on simulations and measurements of the optical absorption of silicon nanowires (NWs) versus their diameter. We first address the simulation of the optical absorption based on two different theoretical methods: the first one, based on the Green function formalism, is useful to calculate the scattering and absorption properties of a single or a finite set of NWs. The second one, based on the finite difference time domain (FDTD) method, is well-adapted to deal with a periodic set of NWs. In both cases, an increase of the onset energy for the absorption is found with increasing diameter. Such effect is experimentally illustrated, when photoconductivity measurements are performed on single tapered Si nanowires connected between a set of several electrodes. An increase of the nanowire diameter reveals a spectral shift of the photocurrent intensity peak towards lower photon energies that allow to tune the absorption onset from the ultraviolet radiations to the visible light spectrum.

  15. A fluorescent benzothiazole probe with efficient two-photon absorption

    NASA Astrophysics Data System (ADS)

    Echevarria, Lorenzo; Moreno, Iván; Camacho, José; Salazar, Mary Carmen; Hernández, Antonio

    2012-11-01

    In this work, we report the two-photon absorption of 2-[4-(dimethylamino)phenyl]-1,3-benzothiazole-6-carbonitrile (DBC) in DMSO solution pumping at 779 nm with a 10 ns pulse laser-Nd:YAG system. The obtained two-photon absorption cross-section in DBC (407 ± 18 GM) is considerably high. Because DBC is a novel compound and have high values of fluorescence quantum yield, this result is expected to have an impact in biomolecules detection, diagnosis and treatment of cancer. Similar structures have previously been reported to show remarkable antitumour effects.

  16. Ultraviolet absorption spectrum of chlorine nitrite, ClONO

    NASA Technical Reports Server (NTRS)

    Molina, L. T.; Molina, M. J.

    1977-01-01

    The near-ultraviolet absorption spectrum of chlorine nitrite (ClONO) has been quantitatively investigated over the wavelength range 230-400 nm at 231 K. An absorption maximum was observed at 290 nm with a cross section of 1.5 by 10 to the -18th power sq cm. The calculated lifetime against photodissociation for ClONO in the atmosphere is 2 to 3 minutes. The large photolysis rate indicates that ClONO does not play a significant role in the stratosphere as a temporary holding tank for chlorine.

  17. Quantification of D-region Absorption

    NASA Astrophysics Data System (ADS)

    Langston, J. S.; Moore, R. C.

    2012-12-01

    An HF cross-modulation technique is employed to probe the D-region ionosphere during modulated HF heating experiments at the High-frequency Active Auroral Research Program (HAARP) observatory. The presented method is a modified version of the more typical pulse-modulated HF cross-modulation experiments during which the ionosphere is heated with a high-power pulsed wave and a second pulsed wave is transmitted at a low-power to probe the modulated D-region. During the modulated heating experiments discussed herein, the high-power wave is instead either an amplitude modulated (AM) wave or continuous wave (CW). It has long since been established that careful measurements of the amplitude and phase of a pulse cross-modulated signal may be used to quantify the ambient and modified characteristics of the D-region ionosphere (e.g. quantifying the ambient and modified D-region conductivity), but with this new transmission, the change in absorption and phase of the low-power pulsed wave can be quantified as a function of modulation duration up to steady-state. This experiment was performed for different heating power levels, different HF frequencies, and different heating waveforms (sinusoidal, square wave, and continuous wave). Experiments were performed at HAARP in September 2011 (two pulse experiment) and February 2012 (three pulse experiment).

  18. Gas-absorption process

    DOEpatents

    Stephenson, Michael J.; Eby, Robert S.

    1978-01-01

    This invention is an improved gas-absorption process for the recovery of a desired component from a feed-gas mixture containing the same. In the preferred form of the invention, the process operations are conducted in a closed-loop system including a gas-liquid contacting column having upper, intermediate, and lower contacting zones. A liquid absorbent for the desired component is circulated through the loop, being passed downwardly through the column, regenerated, withdrawn from a reboiler, and then recycled to the column. A novel technique is employed to concentrate the desired component in a narrow section of the intermediate zone. This technique comprises maintaining the temperature of the liquid-phase input to the intermediate zone at a sufficiently lower value than that of the gas-phase input to the zone to effect condensation of a major part of the absorbent-vapor upflow to the section. This establishes a steep temperature gradient in the section. The stripping factors below this section are selected to ensure that virtually all of the gases in the downflowing absorbent from the section are desorbed. The stripping factors above the section are selected to ensure re-dissolution of the desired component but not the less-soluble diluent gases. As a result, a peak concentration of the desired component is established in the section, and gas rich in that component can be withdrawn therefrom. The new process provides important advantages. The chief advantage is that the process operations can be conducted in a single column in which the contacting zones operate at essentially the same pressure.

  19. Integral light-scattering and absorption characteristics of large, nonspherical particles

    NASA Astrophysics Data System (ADS)

    Kokhanovsky, Alexander A.; Macke, Andreas

    1997-11-01

    We obtain and analyze simple analytical formulas for asymmetry parameters and absorption cross sections of large, nonspherical particles. The formulas are based on the asymptotic properties of these characteristics at strong and weak absorption of radiation inside particles. The absorption cross section depends on parameter , which determines the value of the light-absorption cross section for weakly absorbing particles. It is larger for nonspherical scatterers. The asymmetry parameter depends on two parameters. The first is the asymmetry parameter g0 of a nonspherical, transparent particle with the same shape as an absorbing one. The second parameter, , determines the strength of the influence of light absorption on the value of the asymmetry parameter. Parameter is larger for nonspherical particles. One can find these three parameters ( , g0 , and ) using a ray-tracing code (RTC) for nonabsorbing and weakly absorbing particles. The RTC can then be used to check the accuracy of the equations at any absorption for hexagonal cylinders and spheroids. It is found that the error of computing the absorption cross section and 1 -g (g is the asymmetry parameter) is less than 20% at the refractive index of particles n = 1.333. Values for asymmetry parameters of large, nonabsorbing, spheroidal particles with different aspect ratios are tabulated for the first time to our knowledge. They do not depend on the size of particles and can serve as an independent check of the accuracy of T-matrix codes for large parameters.

  20. Terahertz absorption in GaN epitaxial layers under lateral electric field

    NASA Astrophysics Data System (ADS)

    Balagula, R. M.; Vinnichenko, M. Ya; Melentev, G. A.; Moldavskaya, M. D.; Shalygin, V. A.; Vorobjev, L. E.; Firsov, D. A.; Danilov, S. N.; Suihkonen, S.

    2016-08-01

    Variation of absorption of terahertz radiation in lateral electric field was investigated in GaN epitaxial layers. Different behaviour of the absorption modulation in electric field was observed for radiation polarized along electric field and perpendicular to it. Joint analysis of optical and transport measurements let us obtain field dependencies of mobility, electron concentration and absorption cross-section. For terahertz radiation polarized perpendicular to the electric field, results are in accordance with Drude model of free electron absorption. Another polarization demonstrates significant deviation that is yet to be studied more thoroughly.

  1. Temperature dependence of the ClONO2 UV absorption spectrum

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  2. Varied absorption peaks of dual-band metamaterial absorber analysis by using reflection theory

    NASA Astrophysics Data System (ADS)

    Xiong, Han; Yu, Yan-Tao; Tang, Ming-Chun; Chen, Shi-Yong; Liu, Dan-Ping; Ou, Xiang; Zeng, Hao

    2016-03-01

    Cross-resonator metamaterial absorbers (MMA) have been widely investigated from microwave to optical frequencies. However, only part of the factors influencing the absorption properties were analyzed in previous works at the same time. In order to completely understand how the spacer thickness, dielectric parameter and incidence angle affect the absorption properties of the dual-band MMA, two sets of simulation were performed. It was found that with increasing incident angles, the low-frequency absorption peak showed a blue shift, while the high-frequency absorption peaks showed a red shift. However, with the increase in spacer thickness, both of the absorption peaks showed a red shift. By using the reflection theory expressions, the physical mechanism of the cross-resonator MMA was well explained. This method provides an effective way to analyze multi-band absorber in technology.

  3. Gastrointestinal citrate absorption in nephrolithiasis

    NASA Technical Reports Server (NTRS)

    Fegan, J.; Khan, R.; Poindexter, J.; Pak, C. Y.

    1992-01-01

    Gastrointestinal absorption of citrate was measured in stone patients with idiopathic hypocitraturia to determine if citrate malabsorption could account for low urinary citrate. Citrate absorption was measured directly from recovery of orally administered potassium citrate (40 mEq.) in the intestinal lavage fluid, using an intestinal washout technique. In 7 stone patients citrate absorption, serum citrate levels, peak citrate concentration in serum and area under the curve were not significantly different from those of 7 normal subjects. Citrate absorption was rapid and efficient in both groups, with 96 to 98% absorbed within 3 hours. The absorption of citrate was less efficient from a tablet preparation of potassium citrate than from a liquid preparation, probably due to a delayed release of citrate from wax matrix. However, citrate absorption from solid potassium citrate was still high at 91%, compared to 98% for a liquid preparation. Thus, hypocitraturia is unlikely to be due to an impaired gastrointestinal absorption of citrate in stone patients without overt bowel disease.

  4. Isospin Dependence of Pion Absorption on Nucleon Pairs at Tπ=65 MeV

    NASA Astrophysics Data System (ADS)

    Moinester, M. A.; Gill, D. R.; Vincent, J.; Ashery, D.; Levenson, S.; Alster, J.; Altman, A.; Lichtenstadt, J.; Piasetzky, E.; Aniol, K. A.; Johnson, R. R.; Roser, H. W.; Tacik, R.; Gyles, W.; Barnett, B.; Sobie, R. J.; Gubler, H. P.

    1984-04-01

    Angular distributions of differential cross sections were measured for the first time for pion absorption on a T=1, S=0 nucleon pair and for absorption on a T=0, S=1 pair in the 3He nucleus. A large isospin dependence is observed in the differential cross sections. The ratio of cross sections σ(3He(π+,2p))σ(3He(π-,pn)) is 15.2+/-1.2. The results show evidence of an isoscalar component of the final state in the reaction 3He(π-,pn)n, which cannot be mediated by Δ resonance formation.

  5. Neutron absorption constraints on the composition of 4 Vesta

    USGS Publications Warehouse

    Prettyman, Thomas H.; Mittlefehldt, David W.; Yamashita, Naoyuki; Beck, Andrew W.; Feldman, William C.; Hendricks, John S.; Lawrence, David J.; McCoy, Timothy J.; McSween, Harry Y.; Paplowski, Patrick N.; Reedy, Robert C.; Toplis, Michael J.; Le Corre, Lucille; Mizzon, Hugau; Reddy, Vishnu; Titus, Timothy N.; Raymond, Carol A.; Russell, Christopher T.

    2013-01-01

    Global maps of the macroscopic thermal neutron absorption cross section of Vesta's regolith by the Gamma Ray and Neutron Detector (GRaND) on board the NASA Dawn spacecraft provide constraints on the abundance and distribution of Fe, Ca, Al, Mg, and other rock-forming elements. From a circular, polar low-altitude mapping orbit, GRaND sampled the regolith to decimeter depths with a spatial resolution of about 300 km. At this spatial scale, the variation in neutron absorption is about seven times lower than that of the Moon. The observed variation is consistent with the range of absorption for howardite whole-rock compositions, which further supports the connection between Vesta and the howardite, eucrite, and diogenite meteorites. We find a strong correlation between neutron absorption and the percentage of eucritic materials in howardites and polymict breccias, which enables petrologic mapping of Vesta's surface. The distribution of basaltic eucrite and diogenite determined from neutron absorption measurements is qualitatively similar to that indicated by visible and near infrared spectroscopy. The Rheasilvia basin and ejecta blanket has relatively low absorption, consistent with Mg-rich orthopyroxene. Based on a combination of Fe and neutron absorption measurements, olivine-rich lithologies are not detected on the spatial scales sampled by GRaND. The sensitivity of GRaND to the presence of mantle material is described and implications for the absence of an olivine signature are discussed. High absorption values found in Vesta's “dark” hemisphere, where exogenic hydrogen has accumulated, indicate that this region is richer in basaltic eucrite, representative of Vesta's ancient upper crust.

  6. Neutron absorption constraints on the composition of 4 Vesta

    NASA Astrophysics Data System (ADS)

    Prettyman, Thomas H.; Mittlefehldt, David W.; Yamashita, Naoyuki; Beck, Andrew W.; Feldman, William C.; Hendricks, John S.; Lawrence, David J.; McCoy, Timothy J.; McSween, Harry Y.; Peplowski, Patrick N.; Reedy, Robert C.; Toplis, Michael J.; Corre, Lucille; Mizzon, Hugau; Reddy, Vishnu; Titus, Timothy N.; Raymond, Carol A.; Russell, Christopher T.

    2013-11-01

    Global maps of the macroscopic thermal neutron absorption cross section of Vesta's regolith by the Gamma Ray and Neutron Detector (GRaND) on board the NASA Dawn spacecraft provide constraints on the abundance and distribution of Fe, Ca, Al, Mg, and other rock-forming elements. From a circular, polar low-altitude mapping orbit, GRaND sampled the regolith to decimeter depths with a spatial resolution of about 300 km. At this spatial scale, the variation in neutron absorption is about seven times lower than that of the Moon. The observed variation is consistent with the range of absorption for howardite whole-rock compositions, which further supports the connection between Vesta and the howardite, eucrite, and diogenite meteorites. We find a strong correlation between neutron absorption and the percentage of eucritic materials in howardites and polymict breccias, which enables petrologic mapping of Vesta's surface. The distribution of basaltic eucrite and diogenite determined from neutron absorption measurements is qualitatively similar to that indicated by visible and near infrared spectroscopy. The Rheasilvia basin and ejecta blanket has relatively low absorption, consistent with Mg-rich orthopyroxene. Based on a combination of Fe and neutron absorption measurements, olivine-rich lithologies are not detected on the spatial scales sampled by GRaND. The sensitivity of GRaND to the presence of mantle material is described and implications for the absence of an olivine signature are discussed. High absorption values found in Vesta's "dark" hemisphere, where exogenic hydrogen has accumulated, indicate that this region is richer in basaltic eucrite, representative of Vesta's ancient upper crust.

  7. Continuum Absorption Coefficient of Atoms and Ions

    NASA Technical Reports Server (NTRS)

    Armaly, B. F.

    1979-01-01

    The rate of heat transfer to the heat shield of a Jupiter probe has been estimated to be one order of magnitude higher than any previously experienced in an outer space exploration program. More than one-third of this heat load is due to an emission of continuum radiation from atoms and ions. The existing computer code for calculating the continuum contribution to the total load utilizes a modified version of Biberman's approximate method. The continuum radiation absorption cross sections of a C - H - O - N ablation system were examined in detail. The present computer code was evaluated and updated by being compared with available exact and approximate calculations and correlations of experimental data. A detailed calculation procedure, which can be applied to other atomic species, is presented. The approximate correlations can be made to agree with the available exact and experimental data.

  8. American Red Cross

    MedlinePlus

    ... Espanol Local Red Cross ( ) Change Chapter Edit Zip Code Edit Zip Code Shop the Red Cross Store Toggle Navigation Menu ... Espanol Local Red Cross ( ) Change Chapter Edit Zip Code Edit Zip Code Shop the Red Cross Store ...

  9. Microwave radiation absorption: behavioral effects.

    PubMed

    D'Andrea, J A

    1991-07-01

    The literature contains much evidence that absorption of microwave energy will lead to behavioral changes in man and laboratory animals. The changes include simple perturbations or outright stoppage of ongoing behavior. On one extreme, intense microwave absorption can result in seizures followed by death. On the other extreme, man and animals can hear microwave pulses at very low rates of absorption. Under certain conditions of exposure, animals will avoid microwaves, while under other conditions, they will actively work to obtain warmth produced by microwaves. Some research has shown behavioral effects during chronic exposure to low-level microwaves. The specific absorption rates that produce behavioral effects seem to depend on microwave frequency, but controversy exists over thresholds and mechanism of action. In all cases, however, the behavioral disruptions cease when chronic microwave exposure is terminated. Thermal changes in man and animals during microwave exposure appear to account for all reported behavioral effects.

  10. Dawn Grand Map Vesta Neutron Absorption V1.0

    NASA Astrophysics Data System (ADS)

    Prettyman, T. H.

    2014-06-01

    A global map of a unitless compositional parameter, delta-C_perpendicular (DCP), and propagated 1-sigma uncertainties is provided. DCP varies linearly with the macroscopic thermal neutron absorption cross section of Vesta's regolith. An equation for converting tabulated DCP values to absorption units is provided in this document. DCP was determined from thermal and epithermal neutron counting rates measured by the NASA Dawn mission's Gamma Ray and Neutron Detector (GRaND) while in low altitude mapping orbit, about 210 km from Vesta's surface. The measurements are representative of Vesta's bulk regolith composition to depths of a few decimeters with a spatial resolution of about 300-km full-width-at-half-maximum of arc length on the surface. The methods used to determine neutron absorption are described by PRETTYMANETAL2013.

  11. Azimuthal Doppler shift of absorption spectrum in optical vortex laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Yoshimura, Shinji; Aramaki, Mitsutoshi; Ozawa, Naoya; Terasaka, Kenichiro; Tanaka, Masayoshi; Nagaoka, Kenichi; Morisaki, Tomohiro

    2016-10-01

    Laser spectroscopy is a powerful diagnostic tool for measuring the mean flow velocity of plasma particles. We have been developing a new laser spectroscopy method utilizing an optical vortex beam, which has helical phase fronts corresponding to the phase change in the azimuthal direction. Because of this phase change, a Doppler effect is experienced even by an atom crossing the beam vertically. The additional azimuthal Doppler shift is proportional to the topological charge of optical vortex and is inversely proportional to the distance from the beam axis in which the beam intensity is vanished by destructive interference or the phase singularity. In order to detect the azimuthal Doppler shift, we have performed a laser absorption spectroscopy experiment with the linear ECR plasma device HYPER-I. Since the azimuthal Doppler shift depends on a position in the beam cross section, the absorption spectra at various positions were reconstructed from the transmitted beam intensity measured by a beam profiler. We have observed a clear spatial dependence of the Doppler shift, which qualitatively agreed with theory. Detailed experimental results, as well as remaining issues and future prospect, will be discussed at the meeting. This study was partially supported by JAPS KAKENHI Grand Numbers 15K05365 and 25287152.

  12. Incomplete intestinal absorption of fructose.

    PubMed Central

    Kneepkens, C M; Vonk, R J; Fernandes, J

    1984-01-01

    Intestinal D-fructose absorption in 31 children was investigated using measurements of breath hydrogen. Twenty five children had no abdominal symptoms and six had functional bowel disorders. After ingestion of fructose (2 g/kg bodyweight), 22 children (71%) showed a breath hydrogen increase of more than 10 ppm over basal values, indicating incomplete absorption: the increase averaged 53 ppm, range 12 to 250 ppm. Four of these children experienced abdominal symptoms. Three of the six children with bowel disorders showed incomplete absorption. Seven children were tested again with an equal amount of glucose, and in three of them also of galactose, added to the fructose. The mean maximum breath hydrogen increases were 5 and 10 ppm, respectively, compared with 103 ppm after fructose alone. In one boy several tests were performed with various sugars; fructose was the only sugar incompletely absorbed, and the effect of glucose on fructose absorption was shown to be dependent on the amount added. It is concluded that children have a limited absorptive capacity for fructose. We speculate that the enhancing effect of glucose and galactose on fructose absorption may be due to activation of the fructose carrier. Apple juice in particular contains fructose in excess of glucose and could lead to abdominal symptoms in susceptible children. PMID:6476870

  13. Pressure dependence of Se absorption lines in AlSb

    SciTech Connect

    Hsu, L. |; Haller, E.E.; Ramdas, A.K.

    1996-09-01

    Using far infrared absorption spectroscopy, the authors have investigated electronic transition spectra of Se donors in AlSb as a function of hydrostatic pressure. At least two distinct ground to bound excited state transition lines, which depend quadratically on the pressure, can be seen. At pressures between 30 and 50 kbar, evidence of an anti-crossing between one of the electronic transitions and a peak which they attribute to the 2 zone center LO phonon mode can be seen.

  14. Excited State Absorption Measurements In Some Scintillator Dye Solutions

    NASA Astrophysics Data System (ADS)

    Dharamsi, A., N.; Jong, Shawpin; Hassam, A. B.

    1986-11-01

    Time-resolved excited state triplet-triplet absorption spectra were measured for solutions of 2,5 diphenyloxazole (PPO) and 2,1 napthyl, 5 phenyloxazole (aNPO) in several solvents. Concentration quenching effects due to excimer formation in nonaromatic solvents were observed. A numerical analysis of the experimental results yielded the rate constants for intersystem crossing, triplet quenching by 02, triplet self quenching and the formation of excimers.

  15. Solvent effects on two-photon absorption of dialkylamino substituted distyrylbenzene chromophore

    NASA Astrophysics Data System (ADS)

    Zhao, Ke; Ferrighi, Lara; Frediani, Luca; Wang, Chuan-Kui; Luo, Yi

    2007-05-01

    Solvent effects on the two-photon absorption of a symmetrical diamino substituted distyrylbenzene chromophore have been studied using the density functional response theory in combination with the polarizable continuum model. It is shown that the dielectric medium has a rather small effect both on the bond length alternation and on the one-photon absorption spectrum, but it affects significantly the two-photon absorption cross section. It is found that both one- and two-photon absorptions are extremely sensitive to the planarity of the molecule, and the absorption intensity can be dramatically reduced by the conformation distortion. It has led to the conclusion that the experimentally observed anomalous solvent effect on the two-photon absorption of dialkylamino substituted distyrylbenzene chromophores cannot be attributed to the intrinsic properties of a single molecule and its interaction with solvents.

  16. Solute dispersion in open channel flow with bed absorption

    NASA Astrophysics Data System (ADS)

    Wang, Ping; Chen, G. Q.

    2016-12-01

    Reactive solute dispersion is of essential significance in various ecological and environmental applications. It is only qualitatively known that boundary absorption depletes pollutant around the boundary and reduces the concentration nearby. All the existing studies on this topic have been focused on the longitudinally distributed mean concentration, far from enough to fully characterize the transport process with tremendous cross-sectional concentration nonuniformity. This work presents an analytical study of the evolution of two-dimensional concentration distribution for solute dispersion in a laminar open channel flow with bed absorption. The fourth order Aris-Gill expansion proposed in our previous study (Wang and Chen, 2016b) is further extended for the case with bed absorption to cover the transitional effects of skewness and kurtosis. Results reveal the extremely nonuniform cross-sectional concentration distribution, and demonstrate that concentration at the bed instead of the mean should be used for reliable quantification of the absorption flux. The accurate two-dimensional concentration distribution presented in this study brings important environmental implications such as risk assessment associated with peak concentration position and duration of toxic pollutant cloud in open channel waters.

  17. Nonlinear absorption properties and excited state dynamics of ferrocene.

    PubMed

    Scuppa, Stefano; Orian, Laura; Dini, Danilo; Santi, Saverio; Meneghetti, Moreno

    2009-08-20

    We report on the first observation of reverse saturable absorption by ferrocene (Fc) in toluene using nanosecond pulses at 532 nm. Pump and probe experiments in the visible spectral region show the existence of an excited triplet state with an intersystem crossing quantum yield S1 --> T1 of 0.085 and a molar extinction coefficient epsilon(Fc)(T) of 5650 L mol(-1) cm(-1) at 700 nm. The full understanding of the nonlinear optical behavior of Fc cannot be obtained, however, with a model that includes only the one-photon absorption from T1, but it is mandatory to consider also a simultaneous two-photon absorption from an excited singlet state of Fc (two-photon absorption cross section: 2.4 x 10(-41) cm4 s ph(-1) mol(-1)). The optical spectrum of the ground and triplet state of Fc are calculated within a TD-DFT approach considering several functionals (PBE, BLYP, LDA, OPBE) for the optimization of molecular geometry.

  18. Fat-soluble vitamin intestinal absorption: absorption sites in the intestine and interactions for absorption.

    PubMed

    Goncalves, Aurélie; Roi, Stéphanie; Nowicki, Marion; Dhaussy, Amélie; Huertas, Alain; Amiot, Marie-Josèphe; Reboul, Emmanuelle

    2015-04-01

    The interactions occurring at the intestinal level between the fat-soluble vitamins A, D, E and K (FSVs) are poorly documented. We first determined each FSV absorption profile along the duodenal-colonic axis of mouse intestine to clarify their respective absorption sites. We then investigated the interactions between FSVs during their uptake by Caco-2 cells. Our data show that vitamin A was mostly absorbed in the mouse proximal intestine, while vitamin D was absorbed in the median intestine, and vitamin E and K in the distal intestine. Significant competitive interactions for uptake were then elucidated among vitamin D, E and K, supporting the hypothesis of common absorption pathways. Vitamin A also significantly decreased the uptake of the other FSVs but, conversely, its uptake was not impaired by vitamins D and K and even promoted by vitamin E. These results should be taken into account, especially for supplement formulation, to optimise FSV absorption.

  19. Kinetics of generation, relaxation, and accumulation of electronic excitations under two-photon interband picosecond absorption in tungstate and molibdate crystals

    SciTech Connect

    Lukanin, V. I.; Karasik, A. Ya.

    2013-08-15

    Under two-photon 523.5 nm interband picosecond laser excitation, we measured the kinetics of induced absorption in PbWO{sub 4}, ZnWO{sub 4}, and PbMoO{sub 4} crystals with 532 to 633 nm continuous probe radiation. We obtained real-time information about the dynamics of the generation, relaxation, and accumulations of electronic excitations over a wide time range (from picoseconds to hundreds of seconds) and the 77-300 K temperature range. For the studied crystals, exponential temperature-independent growth of the induced absorption (IA) with 60 ns rise time reflects the dynamics of the generation of electronic excitation. The kinetics of the IA exponential growth with temperature-dependent 3.5-11 {mu}s time constants reflect the dynamics of energy migration between neighboring tungstate (molibdate) ions to traps for the studied crystals. The multiexponential relaxation absorption kinetics strongly depend on temperature, and the relaxation decay time of induced absorption increased from tens to hundreds of milliseconds to seconds under crystal cooling from 300 to 77 K. We found that the increase in the laser pump repetition rate (0-10 Hz) leads to the accumulation of electronic excitations. Control of the repetition rate and the number of excitations allowed us to change the relaxation time of the induced absorption by more than two orders of magnitude. Due to accumulation of excitations at 77 K, the absorption relaxation time can exceed 100 s for PbWO{sub 4} and PbMoO{sub 4} crystals. In the initially transparent crystals, two-photon interband absorption (2PA) leads to crystals opacity at the 523 and 633 nm wavelengths. (An inverse optical transmission of the crystals exceeds 50-55 at a 50-100 GW/cm{sup 2} pump intensity.) Measured at {approx}1 mW probe radiation of 532 and 633 nm wavelengths, the induced absorption values are comparable with those obtained under two-photon absorption at {approx}5 kW pump power. An optical 2PA shutter for the visible spectral range

  20. Absorption and Metabolism of Xanthophylls

    PubMed Central

    Kotake-Nara, Eiichi; Nagao, Akihiko

    2011-01-01

    Dietary carotenoids, especially xanthophylls, have attracted significant attention because of their characteristic biological activities, including anti-allergic, anti-cancer, and anti-obese actions. Although no less than forty carotenoids are ingested under usual dietary habits, only six carotenoids and their metabolites have been found in human tissues, suggesting selectivity in the intestinal absorption of carotenoids. Recently, facilitated diffusion in addition to simple diffusion has been reported to mediate the intestinal absorption of carotenoids in mammals. The selective absorption of carotenoids may be caused by uptake to the intestinal epithelia by the facilitated diffusion and an unknown excretion to intestinal lumen. It is well known that β-carotene can be metabolized to vitamin A after intestinal absorption of carotenoids, but little is known about the metabolic transformation of non provitamin A xanthophylls. The enzymatic oxidation of the secondary hydroxyl group leading to keto-carotenoids would occur as a common pathway of xanthophyll metabolism in mammals. This paper reviews the absorption and metabolism of xanthophylls by introducing recent advances in this field. PMID:21747746

  1. Light absorption properties of brown carbon in the high Himalayas

    NASA Astrophysics Data System (ADS)

    Kirillova, Elena N.; Marinoni, Angela; Bonasoni, Paolo; Vuillermoz, Elisa; Facchini, Maria Cristina; Fuzzi, Sandro; Decesari, Stefano

    2016-08-01

    The light-absorbing properties of water-soluble brown carbon (WS-BrC) and methanol-soluble brown carbon (MeS-BrC) were studied in PM10 aerosols collected at the "Nepal Climate Observatory-Pyramid" (NCO-P) station (5079 m above sea level) during the period 2013-2014. The light absorption coefficients of WS-BrC and MeS-BrC were the highest during the premonsoon season and the lowest during monsoon. MeS-BrC absorbs about 2 times higher at 365 nm and about 3 times more at 550 nm compared to WS-BrC. The mass absorption cross section (MAC) of WS-BrC measured at 365 nm is similar to that observed previously at South Asian low-altitude sites. Fractional solar radiation absorption by BrC compared to BC considering the full solar spectrum showed that WS-BrC absorbs 4 ± 1% and MeS-BrC absorbs 9 ± 2% compared to BC at NCO-P. Such ratios become 8 ± 1% (for WS-BrC respect to BC) and 17 ± 5% (for MeS-BrC respect to BC) when accounting for correction factors proposed by previous studies to convert absorption coefficients in bulk solutions into light absorption by accumulation mode aerosol particles. These results confirm the importance of BrC in contributing to light-absorbing aerosols in this region of the world. However, the BrC absorption at 550 nm appears small compared to that of BC (1-5%, or 3-9% with conversion factors), and it is lower compared to global model estimates constrained by Aerosol Robotic Network observations. Finally, our study provides no clear evidence of a change in the fractional contribution of BrC with respect to BC to light absorption in the middle troposphere respect to the Indo-Gangetic plain boundary layer.

  2. Enhanced absorption cycle computer model

    NASA Astrophysics Data System (ADS)

    Grossman, G.; Wilk, M.

    1993-09-01

    Absorption heat pumps have received renewed and increasing attention in the past two decades. The rising cost of electricity has made the particular features of this heat-powered cycle attractive for both residential and industrial applications. Solar-powered absorption chillers, gas-fired domestic heat pumps, and waste-heat-powered industrial temperature boosters are a few of the applications recently subjected to intensive research and development. The absorption heat pump research community has begun to search for both advanced cycles in various multistage configurations and new working fluid combinations with potential for enhanced performance and reliability. The development of working absorption systems has created a need for reliable and effective system simulations. A computer code has been developed for simulation of absorption systems at steady state in a flexible and modular form, making it possible to investigate various cycle configurations with different working fluids. The code is based on unit subroutines containing the governing equations for the system's components and property subroutines containing thermodynamic properties of the working fluids. The user conveys to the computer an image of his cycle by specifying the different subunits and their interconnections. Based on this information, the program calculates the temperature, flow rate, concentration, pressure, and vapor fraction at each state point in the system, and the heat duty at each unit, from which the coefficient of performance (COP) may be determined. This report describes the code and its operation, including improvements introduced into the present version. Simulation results are described for LiBr-H2O triple-effect cycles, LiCl-H2O solar-powered open absorption cycles, and NH3-H2O single-effect and generator-absorber heat exchange cycles. An appendix contains the user's manual.

  3. Absorption-heat-pump system

    DOEpatents

    Grossman, G.; Perez-Blanco, H.

    1983-06-16

    An improvement in an absorption heat pump cycle is obtained by adding adiabatic absorption and desorption steps to the absorber and desorber of the system. The adiabatic processes make it possible to obtain the highest temperature in the absorber before any heat is removed from it and the lowest temperature in the desorber before heat is added to it, allowing for efficient utilization of the thermodynamic availability of the heat supply stream. The improved system can operate with a larger difference between high and low working fluid concentrations, less circulation losses, and more efficient heat exchange than a conventional system.

  4. Transient absorption spectroscopy of laser shocked explosives

    SciTech Connect

    Mcgrane, Shawn D; Dang, Nhan C; Whitley, Von H; Bolome, Cindy A; Moore, D S

    2010-01-01

    Transient absorption spectra from 390-890 nm of laser shocked RDX, PETN, sapphire, and polyvinylnitrate (PVN) at sub-nanosecond time scales are reported. RDX shows a nearly linear increase in absorption with time after shock at {approx}23 GPa. PETN is similar, but with smaller total absorption. A broad visible absorption in sapphire begins nearly immediately upon shock loading but does not build over time. PVN exhibits thin film interference in the absorption spectra along with increased absorption with time. The absorptions in RDX and PETN are suggested to originate in chemical reactions happening on picosecond time scales at these shock stresses, although further diagnostics are required to prove this interpretation.

  5. Magnetic field control of the intraband optical absorption in two-dimensional quantum rings

    SciTech Connect

    Olendski, O.; Barakat, T.

    2014-02-28

    Linear and nonlinear optical absorption coefficients of the two-dimensional semiconductor ring in the perpendicular magnetic field B are calculated within independent electron approximation. Characteristic feature of the energy spectrum are crossings of the levels with adjacent nonpositive magnetic quantum numbers as the intensity B changes. It is shown that the absorption coefficient of the associated optical transition is drastically decreased at the fields corresponding to the crossing. Proposed model of the Volcano disc allows to get simple mathematical analytical results, which provide clear physical interpretation. An interplay between positive linear and intensity-dependent negative cubic absorption coefficients is discussed; in particular, critical light intensity at which additional resonances appear in the total absorption dependence on the light frequency is calculated as a function of the magnetic field and levels' broadening.

  6. Aerosol Absorption Measurements in MILAGRO.

    NASA Astrophysics Data System (ADS)

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

    2007-12-01

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

  7. Absorption effects in electron-sulfur-dioxide collisions

    SciTech Connect

    Machado, L. E.; Sugohara, R. T.; Santos, A. S. dos; Lee, M.-T.; Iga, I.; Souza, G. L. C. de; Homem, M. G. P.; Michelin, S. E.; Brescansin, L. M.

    2011-09-15

    A joint experimental-theoretical study on electron-SO{sub 2} collisions in the low and intermediate energy range is reported. More specifically, experimental elastic differential, integral, and momentum transfer cross sections in absolute scale are measured in the 100-1000 eV energy range using the relative-flow technique. Calculated elastic differential, integral, and momentum transfer cross sections as well as grand-total and total absorption cross sections are also presented in the 1-1000 eV energy range. A complex optical potential is used to represent the electron-molecule interaction dynamics, whereas the Schwinger variational iterative method combined with the distorted-wave approximation is used to solve the scattering equations. Comparison of the present results is made with the theoretical and experimental results available in the literature.

  8. Metal powder absorptivity: Modeling and experiment

    DOE PAGES

    Boley, C. D.; Mitchell, S. C.; Rubenchik, A. M.; ...

    2016-08-10

    Here, we present results of numerical modeling and direct calorimetric measurements of the powder absorptivity for a number of metals. The modeling results generally correlate well with experiment. We show that the powder absorptivity is determined, to a great extent, by the absorptivity of a flat surface at normal incidence. Our results allow the prediction of the powder absorptivity from normal flat-surface absorptivity measurements.

  9. UV absorption spectrum of the C2 Criegee intermediate CH3CHOO.

    PubMed

    Smith, Mica C; Ting, Wei-Lun; Chang, Chun-Hung; Takahashi, Kaito; Boering, Kristie A; Lin, Jim Jr-Min

    2014-08-21

    The UV spectrum of CH3CHOO was measured by transient absorption in a flow cell at 295 K. The absolute absorption cross sections of CH3CHOO were measured by laser depletion in a molecular beam to be (1.06 ± 0.09) × 10(-17) cm(2) molecule(-1) at 308 nm and (9.7 ± 0.6) × 10(-18) cm(2) molecule(-1) at 352 nm. After scaling the UV spectrum of CH3CHOO to the absolute cross section at 308 nm, the peak UV cross section is (1.27 ± 0.11) × 10(-17) cm(2) molecule(-1) at 328 nm. Compared to the simplest Criegee intermediate CH2OO, the UV absorption band of CH3CHOO is similar in intensity but blue shifted by 14 nm, resulting in a 20% slower photolysis rate estimated for CH3CHOO in the atmosphere.

  10. UV absorption spectrum of the C2 Criegee intermediate CH3CHOO

    NASA Astrophysics Data System (ADS)

    Smith, Mica C.; Ting, Wei-Lun; Chang, Chun-Hung; Takahashi, Kaito; Boering, Kristie A.; Lin, Jim-Min, Jr.

    2014-08-01

    The UV spectrum of CH3CHOO was measured by transient absorption in a flow cell at 295 K. The absolute absorption cross sections of CH3CHOO were measured by laser depletion in a molecular beam to be (1.06 ± 0.09) × 10-17 cm2 molecule-1 at 308 nm and (9.7 ± 0.6) × 10-18 cm2 molecule-1 at 352 nm. After scaling the UV spectrum of CH3CHOO to the absolute cross section at 308 nm, the peak UV cross section is (1.27 ± 0.11) × 10-17 cm2 molecule-1 at 328 nm. Compared to the simplest Criegee intermediate CH2OO, the UV absorption band of CH3CHOO is similar in intensity but blue shifted by 14 nm, resulting in a 20% slower photolysis rate estimated for CH3CHOO in the atmosphere.

  11. Two-photon absorption properties of a new series of 2CTσ chromophores

    NASA Astrophysics Data System (ADS)

    Zhou, Yu-fang; Meng, Fan-qing; Zhao, Xian; Xu, Dong; Jiang, Min-hu

    2000-10-01

    We have designed and synthesized a new series of two-photon ASPT-like charge transfer moieties linked by σ-bond spacers to N-position of pyridine cycle. Both theoretical and experimental results show there is no linear absorption in 600-1300 nm, so two-photon properties can be expected in this range. Two-photon absorption (TPA) cross-sections were calculated by using INDO/CI and SOS methods. The results show that those compounds possess large cross-sections as well as appropriate absorption wavelengths. Also the magnitude of the cross-section changes regularly with the number of the σ-bond spacers. These imply that they are good candidates for two-photon devices.

  12. Emergence of Very Broad Infrared Absorption Band By Hyperdoping of Silicon with Chalcogens

    DTIC Science & Technology

    2013-06-03

    measured by Hall effect in Ref. 9 (crosses) as functions of implanted sulfur dose. (c) Calculated reflectivity by Kramers- Kronig transformation of the...MIR band is small enough, this assumption is reasonable according to the Kramers- Kronig relationship between optical absorption and reflectivity...calculated by a Kramers- Kronig transformation of the absorption spectrum shown in Fig. 1(a) and the results are shown in Fig. 1(c). However, the a value

  13. Low-energy neutron flux measurement using a resonance absorption filter surrounding a lithium glass scintillator

    NASA Astrophysics Data System (ADS)

    Ghal-Eh, N.; Koohi-Fayegh, R.; Hamidi, S.

    2007-06-01

    The resonance absorption filter technique has been used to determine the thermal/epithermal neutron flux. The main idea in this technique is to use an element with a high and essentially singular resonance in the neutron absorption cross section as a filter surrounding a miniature-type lithium glass scintillator. The count with and without the filter surrounding the detector gives the number of resonance-energy neutrons. Some preliminary results and a comparison with the MCNP code are shown.

  14. Theory of graphene saturable absorption

    NASA Astrophysics Data System (ADS)

    Marini, A.; Cox, J. D.; García de Abajo, F. J.

    2017-03-01

    Saturable absorption is a nonperturbative nonlinear optical phenomenon that plays a pivotal role in the generation of ultrafast light pulses. Here we show that this effect emerges in graphene at unprecedentedly low light intensities, thus opening avenues to new nonlinear physics and applications in optical technology. Specifically, we theoretically investigate saturable absorption in extended graphene by developing a semianalytical nonperturbative single-particle approach, describing electron dynamics in the atomically-thin material using the two-dimensional Dirac equation for massless Dirac fermions, which is recast in the form of generalized Bloch equations. By solving the electron dynamics nonperturbatively, we account for both interband and intraband contributions to the intensity-dependent saturated conductivity and conclude that the former dominates regardless of the intrinsic doping state of the material. We obtain results in qualitative agreement with atomistic quantum-mechanical simulations of graphene nanoribbons including electron-electron interactions, finite-size, and higher-band effects. Remarkably, such effects are found to affect mainly the linear absorption, while the predicted saturation intensities are in good quantitative agreement in the limit of extended graphene. Additionally, we find that the modulation depth of saturable absorption in graphene can be electrically manipulated through an externally applied gate voltage. Our results are relevant for the development of graphene-based optoelectronic devices, as well as for applications in mode-locking and random lasers.

  15. Migrant labor absorption in Malaysia.

    PubMed

    Nayagam, J

    1992-01-01

    The use of migrant workers to ease labor shortages caused by rapid industrialization in Malaysia during the twentieth century is examined. "This paper will focus on: (1) the extent, composition and distribution of migrant workers; (2) the labor shortage and absorption of migrant workers; and (3) the role of migrant workers in the government's economic restructuring process."

  16. Quasistellar Objects: Intervening Absorption Lines

    NASA Astrophysics Data System (ADS)

    Charlton, J.; Churchill, C.; Murdin, P.

    2000-11-01

    Every parcel of gas along the line of sight to a distant QUASAR will selectively absorb certain wavelengths of continuum light of the quasar due to the presence of the various chemical elements in the gas. Through the analysis of these quasar absorption lines we can study the spatial distributions, motions, chemical enrichment and ionization histories of gaseous structures from REDSHIFT five unti...

  17. Oxygen Absorption in Cooling Flows.

    PubMed

    Buote

    2000-04-01

    The inhomogeneous cooling flow scenario predicts the existence of large quantities of gas in massive elliptical galaxies, groups, and clusters that have cooled and dropped out of the flow. Using spatially resolved, deprojected X-ray spectra from the ROSAT PSPC, we have detected strong absorption over energies approximately 0.4-0.8 keV intrinsic to the central approximately 1&arcmin; of the galaxy NGC 1399, the group NGC 5044, and the cluster A1795. These systems have among the largest nearby cooling flows in their respective classes and low Galactic columns. Since no excess absorption is indicated for energies below approximately 0.4 keV, the most reasonable model for the absorber is warm, collisionally ionized gas with T=105-106 K in which ionized states of oxygen provide most of the absorption. Attributing the absorption only to ionized gas reconciles the large columns of cold H and He inferred from Einstein and ASCA with the lack of such columns inferred from ROSAT and also is consistent with the negligible atomic and molecular H inferred from H i and CO observations of cooling flows. The prediction of warm ionized gas as the product of mass dropout in these and other cooling flows can be verified by Chandra and X-Ray Multimirror Mission.

  18. Ultraviolet and Light Absorption Spectrometry.

    ERIC Educational Resources Information Center

    Hargis, L. G.; Howell, J. A.

    1984-01-01

    Reviews developments in ultraviolet and light absorption spectrometry from December 1981 through November 1983, focusing on the chemistry involved in developing suitable reagents, absorbing systems, and methods of determination, and on physical aspects of the procedures. Includes lists of spectrophotometric methods for metals, non-metals, and…

  19. Slow light and saturable absorption

    NASA Astrophysics Data System (ADS)

    Selden, A. C.

    2009-06-01

    Quantitative analysis of slow light experiments utilising coherent population oscillation (CPO) in a range of saturably absorbing media, including ruby and alexandrite, Er3+:Y2SiO5, bacteriorhodopsin, semiconductor quantum devices and erbium-doped optical fibres, shows that the observations may be more simply interpreted as saturable absorption phenomena. A basic two-level model of a saturable absorber displays all the effects normally associated with slow light, namely phase shift and modulation gain of the transmitted signal, hole burning in the modulation frequency spectrum and power broadening of the spectral hole, each arising from the finite response time of the non-linear absorption. Only where hole-burning in the optical spectrum is observed (using independent pump and probe beams), or pulse delays exceeding the limits set by saturable absorption are obtained, can reasonable confidence be placed in the observation of slow light in such experiments. Superluminal (“fast light”) phenomena in media with reverse saturable absorption (RSA) may be similarly explained.

  20. Optical Model and Cross Section Uncertainties

    SciTech Connect

    Herman,M.W.; Pigni, M.T.; Dietrich, F.S.; Oblozinsky, P.

    2009-10-05

    Distinct minima and maxima in the neutron total cross section uncertainties were observed in model calculations using spherical optical potential. We found this oscillating structure to be a general feature of quantum mechanical wave scattering. Specifically, we analyzed neutron interaction with 56Fe from 1 keV up to 65 MeV, and investigated physical origin of the minima.We discuss their potential importance for practical applications as well as the implications for the uncertainties in total and absorption cross sections.

  1. Light Absorption By Coated Soot

    NASA Astrophysics Data System (ADS)

    Sedlacek, A. J.; Lee, J.; Onasch, T. B.; Davidovits, P.; Cross, E. S.

    2009-12-01

    The contribution of aerosol absorption on direct radiative forcing is still an active area of research, in part, because aerosol extinction is dominated by light scattering and, in part, because the primary absorbing aerosol of interest, soot, exhibits complex aging behavior that alters its optical properties. The consequences of this can be evidenced by the work of Ramanathan and Carmichael (2008) who suggest that incorporating the atmospheric heating due to brown clouds will increase black carbon (BC) radiative forcing from the IPCC best estimate of 0.34 Wm-2 (±0.25 Wm-2) (IPCC 2007) to 0.9 Wm-2. This noteworthy degree of the uncertainty is due largely to the interdependence of BC optical properties on particle mixing state and aggregate morphology, each of which changes as the particle ages in the atmosphere and becomes encapsulated within a coating of inorganic and/or organic substances. With the advent of techniques that can directly measure aerosol light absorption without influences due to collection substrate or light scattering (e.g., photoacoustic spectroscopy (Arnott et al., 2005; Lack et al., 2006) and photothermal interferometry (Sedlacek and Lee 2007)) the potential exists for quantifying this interdependence. In July 2008, a laboratory-based measurement campaign, led by Boston College and Aerodyne, was initiated to begin addressing this interdependence. To achieve this objective measurements of both the optical and physical properties of flame-generated soot under nascent, coated and denuded conditions were conducted. In this paper, light absorption by dioctyl sebacate (DOS) encapsulated soot and sulfuric acid coated soot using the technique of photothermal interferometry will be presented. In the case of DOS-coated soot, a monotonic increase in light absorption as a function DOS coating thickness to nearly 100% is observed. This observation is consistent with a coating-induced amplification in particle light absorption. (Bond et al. 2006) However

  2. Optical absorptions of polyfluorene transistors

    NASA Astrophysics Data System (ADS)

    Deng, Yvonne Y.; Sirringhaus, Henning

    2005-07-01

    Conjugated polymers are a promising class of materials for organic electronics. While the progress in device performance is impressive, the basics of charge transport still pose many open questions. Specifically, conduction at the comparatively rough polymer-polymer interface in an all-polymer field-effect transistor is expected to be different from a sharp interface with an inorganic dielectric, such as silicon dioxide. In this work, charge modulation spectroscopy (CMS) is used to study the optical absorptions in the presence of charges in situ in the transistor structure. This allows direct observation of the charge carriers in the operational device via their spectroscopic signature; the technique is by design very sensitive to the properties of the semiconductor-dielectric interface. The semiconducting copolymer poly( 9,9' -dioctyl-fluorene-co-bithiophene) (F8T2) is incorporated into a top-gate thin-film transistor structure with a polymer dielectric layer deposited by spin coating and inkjet-printed polymer electrodes. A prominent charge-induced absorption at 1.65eV is observed as well as a shoulder at 1.3eV and a tail extending toward the absorption edge. The bias dependence of the CMS signature confirms that intermixing of the polymer layers is minimal, as expected from the excellent transistor characteristics. Polarization-dependent CMS measurements on aligned transistors show that the main feature at 1.65eV is strongly polarized whereas the shoulder is unpolarized. This observation, as well as further experimental evidence, lead to the conclusion that while the main absorption is attributable to the intrinsic, polaronic absorption in F8T2, the shoulder is likely to originate from a defect state.

  3. Nonlinear optical properties of tetrapyrazinoporphyrazinato indium chloride complexes due to excited-state absorption processes.

    PubMed

    Dini, Danilo; Hanack, Michael; Meneghetti, Moreno

    2005-07-07

    The multiphoton absorption properties of the axially substituted tetrapyrazinotetraazaporphyrinato complex Pyz(4)TAPInCl (1) are reported and interpreted. In particular, the nonlinear optical transmission of the complex and the excited states involved in the nonlinear absorption have been determined at the frequency of the second harmonic generation of a Nd:YAG laser in the nanosecond time regime. Pyz(4)TAPInCl has an excited-state absorption cross section larger than its ground state in the 460-540 nm spectral region, and it shows an optical limiting (OL) behavior at 532 nm, which derives from a sequential two-photon absorption with a larger absorption cross section of the excited triplet state with respect to the ground state. It results that the absorption cross section of 1 in the excited triplet state is 7.8 x 10(-18) cm(2) vs 0.9 x 10(-18) cm(2) of the ground state at the wavelength of OL analysis.

  4. Investigation of black and brown carbon multiple-wavelength-dependent light absorption from biomass and fossil fuel combustion source emissions

    NASA Astrophysics Data System (ADS)

    Olson, Michael R.; Victoria Garcia, Mercedes; Robinson, Michael A.; Van Rooy, Paul; Dietenberger, Mark A.; Bergin, Michael; Schauer, James Jay

    2015-07-01

    Quantification of the black carbon (BC) and brown carbon (BrC) components of source emissions is critical to understanding the impact combustion aerosols have on atmospheric light absorption. Multiple-wavelength absorption was measured from fuels including wood, agricultural biomass, coals, plant matter, and petroleum distillates in controlled combustion settings. Filter-based absorption measurements were corrected and compared to photoacoustic absorption results. BC absorption was segregated from the total light extinction to estimate the BrC absorption from individual sources. Results were compared to elemental carbon (EC)/organic carbon (OC) concentrations to determine composition's impact on light absorption. Multiple-wavelength absorption coefficients, Angstrom exponent (6.9 to <1.0), mass absorption cross section (MAC), and Delta C (97 µg m-3 to ~0 µg m-3) were highly variable. Sources such as incense and peat emissions showed ultraviolet wavelength (370 nm) BrC absorption over 175 and 80 times (respectively) the BC absorption but only 21 and 11 times (respectively) at 520 nm wavelength. The bulk EC MACEC, λ (average at 520 nm = 9.0 ± 3.7 m2 g-1; with OC fraction <0.85 = ~7.5 m2 g-1) and the BrC OC mass absorption cross sections (MACBrC,OC,λ) were calculated; at 370 nm ultraviolet wavelengths; the MACBrC,OC,λ ranged from 0.8 m2 g-1 to 2.29 m2 g-1 (lowest peat, highest kerosene), while at 520 nm wavelength MACBrC,OC,λ ranged from 0.07 m2 g-1 to 0.37 m2 g-1 (lowest peat, highest kerosene/incense mixture). These MAC results show that OC content can be an important contributor to light absorption when present in significant quantities (>0.9 OC/TC), source emissions have variable absorption spectra, and nonbiomass combustion sources can be significant contributors to BrC.

  5. Microscopic description of intraband absorption in graphene: the occurrence of transient negative differential transmission.

    PubMed

    Kadi, Faris; Winzer, Torben; Malic, Ermin; Knorr, Andreas; Göttfert, F; Mittendorff, M; Winnerl, S; Helm, M

    2014-07-18

    We present a microscopic explanation of the controversially discussed transient negative differential transmission observed in degenerate optical pump-probe measurements in graphene. Our approach is based on the density matrix formalism allowing a time- and momentum-resolved study of carrier-light, carrier-carrier, and carrier-phonon interaction on microscopic footing. We show that phonon-assisted optical intraband transitions give rise to transient absorption in the optically excited hot carrier system counteracting pure absorption bleaching of interband transitions. While interband transition bleaching is relevant in the first hundreds of fs after the excitation, intraband absorption sets in at later times. In particular, in the low excitation regime, these intraband absorption processes prevail over the absorption bleaching resulting in a zero crossing of the differential transmission. Our findings are in good qualitative agreement with recent experimental pump-probe studies.

  6. Excited state two photon absorption of a charge transfer radical dimer in the near infrared.

    PubMed

    Schiccheri, Nicola; Meneghetti, Moreno

    2005-06-02

    Nonlinear transmission measurements of a solution of radical dimers of tetramethyl-tetrathiafulvalene, (TMTTF+)2, recorded with 9 ns laser pulses at 1064 nm are reported and interpreted on the basis of a multiphoton absorption process. One finds that the process can be interpreted with a sequence of three photon absorption, the first being a one photon absorption related to the intermolecular charge transfer process characteristic of the dimers and the second a two photon absorption from the excited state created with the first process. A model calculation allows one to obtain the value of the two photon absorption cross section which is found to be several orders of magnitude larger than those usually found for two photon absorbing systems excited from the ground state. These results show the importance of an excited-state population for obtaining large nonlinear optical responses.

  7. Nonlinear optical effects related to saturable and reverse saturable absorption by subphthalocyanines at 532 nm.

    PubMed

    Dini, Danilo; Vagin, Sergej; Hanack, Michael; Amendola, Vincenzo; Meneghetti, Moreno

    2005-08-14

    It is found that both effects of saturable absorption and reverse saturable absorption are obtained with a solution of subphthalocyanine at 532 nm depending on the intensity of 9 ns laser pulses; saturable absorption occurs at lower intensity levels whereas the reverse effect prevails at higher levels; contrary to expectations, subphthalocyanines can behave as reverse saturable absorbers at 532 nm, despite the high linear absorption at this wavelength; data have been fitted with a five-level model which considers three consecutive electronic transitions with absorption cross-section values of 1.4 x 10(-16), 1.0 x 10(-16) and 40 x 10(-16) cm(2), respectively.

  8. Electromagnetic absorption properties of spacecraft and space debris

    NASA Astrophysics Data System (ADS)

    Micheli, D.; Santoni, F.; Giusti, A.; Delfini, A.; Pastore, R.; Vricella, A.; Albano, M.; Arena, L.; Piergentili, F.; Marchetti, M.

    2017-04-01

    Aim of the work is to present a method to evaluate the electromagnetic absorption properties of spacecraft and space debris. For these objects, the radar detection ability depends mainly on volume, shape, materials type and other electromagnetic reflecting behaviour of spacecraft surface components, such as antennas or thermal blankets, and of metallic components in space debris. The higher the electromagnetic reflection coefficient of such parts, the greater the radar detection possibility. In this research an electromagnetic reverberation chamber is used to measure the absorption cross section (ACS) of four objects which may represent space structure operating components as well as examples of space debris: a small satellite, a composite antenna dish, a Thermal Protection System (TPS) tile and a carbon-based composite missile shell. The ACS mainly depends on geometrical characteristics like apertures, face numbers and bulk porosity, as well as on the type of the material itself. The ACS, which is an electromagnetic measurement, is expressed in squared meters and thus can be compared with the objects geometrical cross section. A small ACS means a quite electromagnetic reflective tendency, which is beneficial for radar observations; on the contrary, high values of ACS indicate a strong absorption of the electromagnetic field, which in turn can result a critical hindering of radar tracking.

  9. Subpicosecond reverse saturable absorption in organic and organometallic solutions

    NASA Astrophysics Data System (ADS)

    Pittman, M.; Plaza, P.; Martin, M. M.; Meyer, Y. H.

    1998-12-01

    Solutions of several carbocyanines, phthalocyanines and naphthalocyanines were studied by time-resolved transient spectroscopy with subpicosecond white-light continuum. The excited-state absorption cross-sections of all compounds were determined from the differential spectra obtained at short delay time after excitation, by a global spectral analysis. All these molecules exhibit an excited-state absorption cross-section higher than that of the ground state at 610 nm. This spectral property gives rise to a reverse saturable absorption (RSA) effect under high laser fluences at this wavelength. Nonlinear transmission of these molecules was measured under increasing laser fluences. A three-level molecular model was used to simulate the measured nonlinear transmission and the best fits were obtained with molecular parameters in good agreement with those deduced from the analysis of the transient spectra. The use of RSA for the energy stabilization of ultrashort laser pulses was demonstrated, and a stabilization coefficient was defined as an efficient tool for characterizing nonlinear behavior of such compounds.

  10. Absorption and scattering of light by VO2 nanoparticle array

    NASA Astrophysics Data System (ADS)

    Yu, Xiaojing; Li, Yi; Wang, Haifang; Zhang, Hu; Zhang, Wei; Huang, Yize

    2009-07-01

    Much attention has been paid to the semiconductor-metal phase transition in vanadium dioxide nanomaterials, accompanied with an abrupt change in its resistivity and near-infrared transmission. The phase transition and optical properties of vanadium dioxide nanoparticles were studied by the mathematical model based on the complex refractive changing with the temperature and wavelength. The optical properties of nano-array were investigated by using the discrete dipole approximation and Mie scattering theory, as well as the absorption and scattering properties of small particles. The results show that the main contribution to the optical response with variational wavelength in the infrared is from absorption cross section comparing with the scattering cross section. It is obvious that the absorption peak of metal phase occurs near 980nm. With the change of temperature, the variation of extinction coefficient is larger in the infrared region than in the visible region. The largest change of extinction coefficient occurs in the near-infrared region. The extincition coefficient is very small in the visible region and there is a maximal value in the infrared region in the nano-array.

  11. Two-photon absorption of [2.2]paracyclophane derivatives in solution: A theoretical investigation

    NASA Astrophysics Data System (ADS)

    Ferrighi, Lara; Frediani, Luca; Fossgaard, Eirik; Ruud, Kenneth

    2007-12-01

    The two-photon absorption of a class of [2.2]paracyclophane derivatives has been studied using quadratic response and density functional theories. For the molecules investigated, several effects influencing the two-photon absorption spectra have been investigated, such as side-chain elongation, hydrogen bonding, the use of ionic species, and solvent effects, the latter described by the polarizable continuum model. The calculations have been carried out using a recent parallel implementation of the polarizable continuum model in the DALTON code. Special attention is given to those aspects that could explain the large solvent effect on the two-photon absorption cross sections observed experimentally for this class of compounds.

  12. The UV absorption spectrum of the simplest Criegee intermediate CH2OO.

    PubMed

    Ting, Wei-Lun; Chen, Ying-Hsuan; Chao, Wen; Smith, Mica C; Lin, Jim Jr-Min

    2014-06-14

    SO2 scavenging and self-reaction of CH2OO were utilized for the decay of CH2OO to extract the absorption spectrum of CH2OO under bulk conditions. Absolute absorption cross sections of CH2OO at 308.4 and 351.8 nm were obtained from laser-depletion measurements in a jet-cooled molecular beam. The peak cross section is (1.23 ± 0.18) × 10(-17) cm(2) at 340 nm.

  13. Novel xenon calibration scheme for two-photon absorption laser induced fluorescence of hydrogen

    NASA Astrophysics Data System (ADS)

    Elliott, Drew; Scime, Earl; Short, Zachary

    2016-11-01

    Two photon absorption laser induced fluorescence (TALIF) measurements of neutral hydrogen and its isotopes are typically calibrated by performing TALIF measurements on krypton with the same diagnostic system and using the known ratio of the absorption cross sections [K. Niemi et al., J. Phys. D 34, 2330 (2001)]. Here we present the measurements of a new calibration method based on a ground state xenon scheme for which the fluorescent emission wavelength is nearly identical to that of hydrogen, thereby eliminating chromatic effects in the collection optics and simplifying detector calibration. We determine that the ratio of the TALIF cross sections of xenon and hydrogen is 0.024 ± 0.001.

  14. True absorption and scattering of pions on 16O and 18O

    NASA Astrophysics Data System (ADS)

    Navon, I.; Piasetzky, E.; Ashery, D.; Altman, A.; Azuelos, G.; Schlepütz, F. W.; Walter, H. K.

    1980-10-01

    The inclusive pion inelastic scattering and true absorption cross sections on 16O and 18O were measured at 165 MeV for π± and at 315 MeV for π+. The results show large effects of the two neutrons in 18O on the absorption and inelastic scattering cross sections at the resonance energy. In particular, the inelastic scattering of π+ from 18O is considerably smaller than from 16O and this effect is attributed to the coupling between the reaction channels.

  15. Infrasound absorption by atmospheric clouds

    NASA Astrophysics Data System (ADS)

    Baudoin, Michael; Coulouvrat, Francois; Thomas, Jean-Louis

    2010-05-01

    A model is developed for the absorption of infrasound by atmospheric clouds made of a suspension of liquid water droplets within a gaseous mixture of water vapor and air. The model is based on the work of D.A. Gubaidullin and R.I. Nigmatulin [Int. J. Multiphase Flow, 26, 207-228, 2000], which is applied to atmospheric clouds. Three physical mechanisms are included : unsteady viscous drag associated with momentum transfers due to the translation of water droplets, unsteady thermal transfers between the liquid and gaseous phases, and mass transfers due to the evaporation or condensation of the water phase. For clouds, in the infrasonic frequency range, phase changes are the dominant mechanisms (around 1 Hz), while viscous and heat transfers become significant only around 100 Hz. Mass transfers involve two physical effects : evaporation and condensation of the water phase at the droplet surface, and diffusion of the water vapor within the gaseous phase. The first one is described through the Hertz-Knudsen-Langmuir theory based on kinetic theory. It involves a little known coefficient known as coefficient of accommodation. The second one is the classical Fick diffusion. For clouds, and unless the coefficient of accommodation is very small (far from the generally recommended value is close to one), diffusion is the main limiting effects for mass transfers. In a second stage, the sound and infrasound absorption is evaluated for various typical clouds up to about 4 km altitude. Above this altitude, the ice content of clouds is dominant compared to their water content, and the present model is not applicable. Cloud thickness, water content, and droplets size distribution are shown to be the major factors influencing the infrasound absorption. A variety of clouds have been analyzed. In most cases, it is shown that infrasound absorption within clouds is several orders larger than classical absorption (due to molecular relaxation of nitrogen and oxygen molecules in presence

  16. Iodine Absorption Cells Purity Testing.

    PubMed

    Hrabina, Jan; Zucco, Massimo; Philippe, Charles; Pham, Tuan Minh; Holá, Miroslava; Acef, Ouali; Lazar, Josef; Číp, Ondřej

    2017-01-06

    This article deals with the evaluation of the chemical purity of iodine-filled absorption cells and the optical frequency references used for the frequency locking of laser standards. We summarize the recent trends and progress in absorption cell technology and we focus on methods for iodine cell purity testing. We compare two independent experimental systems based on the laser-induced fluorescence method, showing an improvement of measurement uncertainty by introducing a compensation system reducing unwanted influences. We show the advantages of this technique, which is relatively simple and does not require extensive hardware equipment. As an alternative to the traditionally used methods we propose an approach of hyperfine transitions' spectral linewidth measurement. The key characteristic of this method is demonstrated on a set of testing iodine cells. The relationship between laser-induced fluorescence and transition linewidth methods will be presented as well as a summary of the advantages and disadvantages of the proposed technique (in comparison with traditional measurement approaches).

  17. Landing gear energy absorption system

    NASA Technical Reports Server (NTRS)

    Hansen, Christopher P. (Inventor)

    1994-01-01

    A landing pad system is described for absorbing horizontal and vertical impact forces upon engagement with a landing surface where circumferentially arranged landing struts respectively have a clevis which receives a slidable rod member and where the upper portion of a slidable rod member is coupled to the clevis by friction washers which are force fit onto the rod member to provide for controlled constant force energy absorption when the rod member moves relative to the clevis. The lower end of the friction rod is pivotally attached by a ball and socket to a support plate where the support plate is arranged to slide in a transverse direction relative to a housing which contains an energy absorption material for absorbing energy in a transverse direction.

  18. The Intestinal Absorption of Folates

    PubMed Central

    Visentin, Michele; Diop-Bove, Ndeye; Zhao, Rongbao; Goldman, I. David

    2014-01-01

    The properties of intestinal folate absorption were documented decades ago. However, it was only recently that the proton-coupled folate transporter (PCFT) was identified and its critical role in folate transport across the apical brush-border membrane of the proximal small intestine established by the loss-of-function mutations identified in the PCFT gene in subjects with hereditary folate malabsorption and, more recently, by the Pcft-null mouse. This article reviews the current understanding of the properties of PCFT-mediated transport and how they differ from those of the reduced folate carrier. Other processes that contribute to the transport of folates across the enterocyte, along with the contribution of the enterohepatic circulation, are considered. Important unresolved issues are addressed, including the mechanism of intestinal folate absorption in the absence of PCFT and regulation of PCFT gene expression. The impact of a variety of ions, organic molecules, and drugs on PCFT-mediated folate transport is described. PMID:24512081

  19. Optical absorption in trilayer graphene

    NASA Astrophysics Data System (ADS)

    Li, Xiao; Zhang, Fan; Niu, Qian

    2013-03-01

    We use a low energy effective model to analyze the optical responses of trilayer graphene samples. We first show that optical absorption of the ABA-stacked trilayer has strong dependence on both the Fermi energy and optical frequency, which is in sharp contrast to that of ABC-stacked trilayer graphene. Secondly, we are able to determine the possible existence of trigonal warping effects in the bandstructure of ABC-stacked trilayer graphene by a divergence in the absorption spectra at around 10 meV. In addition, we can partially distinguish the vairious broken symmetry states driven by electron-electron interactions in ABC-stacked trilayer graphene. In particular, the quantum anomalous Hall (QAH) state is sensitive to the polarization of the incident light, giving a way to detect its possible existence.

  20. Free-free absorption of infrared radiation in collisions of electrons with neutral rare-gas atoms

    NASA Technical Reports Server (NTRS)

    Stallcop, J. R.

    1974-01-01

    A relationship between the inverse bremsstrahlung absorption cross section and the electron neutral momentum transfer cross section has been utilized to determine the infrared free-free continuum absorption coefficient for the negative ions of helium, neon, argon, krypton, and xenon. The values of the momentum transfer cross section for this calculation have been obtained from experimental measurements. Analytical expressions for the absorption coefficient have also been developed. From the results of this calculation, it is possible to determine the absorption coefficient per unit electron density per neutral atom for temperatures in the range from 2500 to 25,000 K. The results are compared with those from tabulations of previous calculations and those computed from theoretical values of the phase shifts for the elastic scattering of electrons by neutral atoms.

  1. Time-resolved postdischarge absolute silicon monoxide density measurement by resonant absorption spectroscopy in a nonthermal atmospheric plasma

    SciTech Connect

    Motret, Olivier; Coursimault, Fabien; Pouvesle, Jean-Michel

    2006-11-01

    In this study we present the technique of resonant absorption spectroscopy diagnostic developed to estimate the density of silicon monoxide (SiO) molecules during the postdischarge of an atmospheric dielectric barrier discharge plasma. The ultraviolet (0,0) rovibrational band of the SiO(A {sup 1}{pi}-X {sup 1}{sigma}{sup +}) electronic transition was investigated. Effective values of absorption coefficient and absorption cross section for the rotational transitions under consideration were calculated. The SiO concentration was estimated by comparison between experimental and computed spectra. The self-absorption in the probe reactor was taken into account in the computed spectra.

  2. Optical Absorption Characteristics of Aerosols.

    DTIC Science & Technology

    1985-09-11

    properties of the powder as well as the thickness of the layer. For a layer that is thick enough so that no light is transmitted, the Kubelka -- Munk theory...which is a two stream radiative transfer model, relates the reflectance to the ratio of the absorption to the scattering. The Kubelka - Munk theory has...of the aerosol material is known. Under the assumptions of the Kubelka - Munk . theory, the imaginary component of the refractive index is deter- mined

  3. Photodetector with enhanced light absorption

    DOEpatents

    Kane, James

    1985-01-01

    A photodetector including a light transmissive electrically conducting layer having a textured surface with a semiconductor body thereon. This layer traps incident light thereby enhancing the absorption of light by the semiconductor body. A photodetector comprising a textured light transmissive electrically conducting layer of SnO.sub.2 and a body of hydrogenated amorphous silicon has a conversion efficiency about fifty percent greater than that of comparative cells. The invention also includes a method of fabricating the photodetector of the invention.

  4. Photochemical cleavage of individual stereoisomers of coumarin-5-fluorouracil crossdimers via single- and two-photon-absorption

    NASA Astrophysics Data System (ADS)

    Behrendt, Philipp J.; Kim, Hee-Cheol; Hampp, Norbert

    2013-11-01

    Coumarin-5-fluorouracil crossdimers were photochemically synthesized. Three different isomers were isolated and their photo-cycloreversion, induced by single- and two-photon-absorption, was studied. The single-photon absorption quantum yields strongly correlate with the dipole moments and the absorption behavior of the stereoisomers. Between the stereoisomers a maximal factor of 6.5 in cyclobutane cleavage efficiency is observed. The two-photon-absorption cross-sections were determined for all three stereoisomers. A good correlation between the single and two-photon-absorption cross-sections was found. The isomer with the highest light sensitivity is the syn-head-to-head isomer. For most applications, isomer pure preparations seem advisable as the required light intensities may be reduced significantly.

  5. A Comprehensive X-Ray Absorption Model for Atomic Oxygen

    NASA Technical Reports Server (NTRS)

    Gorczyca, T. W.; Bautista, M. A.; Hasoglu, M. F.; Garcia, J.; Gatuzz, E.; Kaastra, J. S.; Kallman, T. R.; Manson, S. T.; Mendoza, C.; Raassen, A. J. J.; de Vries, C. P.; Zatsarinny, O.

    2013-01-01

    An analytical formula is developed to accurately represent the photoabsorption cross section of atomic Oxygen for all energies of interest in X-ray spectral modeling. In the vicinity of the K edge, a Rydberg series expression is used to fit R-matrix results, including important orbital relaxation effects, that accurately predict the absorption oscillator strengths below threshold and merge consistently and continuously to the above-threshold cross section. Further, minor adjustments are made to the threshold energies in order to reliably align the atomic Rydberg resonances after consideration of both experimental and observed line positions. At energies far below or above the K-edge region, the formulation is based on both outer- and inner-shell direct photoionization, including significant shake-up and shake-off processes that result in photoionization-excitation and double-photoionization contributions to the total cross section. The ultimate purpose for developing a definitive model for oxygen absorption is to resolve standing discrepancies between the astronomically observed and laboratory-measured line positions, and between the inferred atomic and molecular oxygen abundances in the interstellar medium from XSTAR and SPEX spectral models.

  6. A comprehensive X-ray absorption model for atomic oxygen

    SciTech Connect

    Gorczyca, T. W.; Bautista, M. A.; Mendoza, C.; Hasoglu, M. F.; García, J.; Gatuzz, E.; Kaastra, J. S.; Raassen, A. J. J.; De Vries, C. P.; Kallman, T. R.; Manson, S. T.; Zatsarinny, O.

    2013-12-10

    An analytical formula is developed to accurately represent the photoabsorption cross section of O I for all energies of interest in X-ray spectral modeling. In the vicinity of the K edge, a Rydberg series expression is used to fit R-matrix results, including important orbital relaxation effects, that accurately predict the absorption oscillator strengths below threshold and merge consistently and continuously to the above-threshold cross section. Further, minor adjustments are made to the threshold energies in order to reliably align the atomic Rydberg resonances after consideration of both experimental and observed line positions. At energies far below or above the K-edge region, the formulation is based on both outer- and inner-shell direct photoionization, including significant shake-up and shake-off processes that result in photoionization-excitation and double-photoionization contributions to the total cross section. The ultimate purpose for developing a definitive model for oxygen absorption is to resolve standing discrepancies between the astronomically observed and laboratory-measured line positions, and between the inferred atomic and molecular oxygen abundances in the interstellar medium from XSTAR and SPEX spectral models.

  7. A High Spectral Resolution Lidar Based on Absorption Filter

    NASA Technical Reports Server (NTRS)

    Piironen, Paivi

    1996-01-01

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

  8. Geometric model from microscopic theory for nuclear absorption

    NASA Technical Reports Server (NTRS)

    John, Sarah; Townsend, Lawrence W.; Wilson, John W.; Tripathi, Ram K.

    1993-01-01

    A parameter-free geometric model for nuclear absorption is derived herein from microscopic theory. The expression for the absorption cross section in the eikonal approximation, taken in integral form, is separated into a geometric contribution that is described by an energy-dependent effective radius and two surface terms that cancel in an asymptotic series expansion. For collisions of light nuclei, an expression for the effective radius is derived from harmonic oscillator nuclear density functions. A direct extension to heavy nuclei with Woods-Saxon densities is made by identifying the equivalent half-density radius for the harmonic oscillator functions. Coulomb corrections are incorporated, and a simplified geometric form of the Bradt-Peters type is obtained. Results spanning the energy range from 1 MeV/nucleon to 1 GeV/nucleon are presented. Good agreement with experimental results is obtained.

  9. Absorption Spectroscopy in Homogeneous and Micellar Solutions.

    ERIC Educational Resources Information Center

    Shah, S. Sadiq; Henscheid, Leonard G.

    1983-01-01

    Describes an experiment which has helped physical chemistry students learn principles of absorption spectroscopy, the effect of solvent polarity on absorption spectra, and some micellar chemistry. Background information and experimental procedures are provided. (JN)

  10. Absorption, Creativity, Peak Experiences, Empathy, and Psychoticism.

    ERIC Educational Resources Information Center

    Mathes, Eugene W.; And Others

    Tellegen and Atkinson suggested that the trait of absorption may play a part in meditative skill, creativity, capacity for peak experiences, and empathy. Although the absorption-meditative skill relationship has been confirmed, other predictions have not been tested. Tellegen and Atkinson's Absorption Scale was completed by undergraduates in four…

  11. Automatic Locking of Laser Frequency to an Absorption Peak

    NASA Technical Reports Server (NTRS)

    Koch, Grady J.

    2006-01-01

    An electronic system adjusts the frequency of a tunable laser, eventually locking the frequency to a peak in the optical absorption spectrum of a gas (or of a Fabry-Perot cavity that has an absorption peak like that of a gas). This system was developed to enable precise locking of the frequency of a laser used in differential absorption LIDAR measurements of trace atmospheric gases. This system also has great commercial potential as a prototype of means for precise control of frequencies of lasers in future dense wavelength-division-multiplexing optical communications systems. The operation of this system is completely automatic: Unlike in the operation of some prior laser-frequency-locking systems, there is ordinarily no need for a human operator to adjust the frequency manually to an initial value close enough to the peak to enable automatic locking to take over. Instead, this system also automatically performs the initial adjustment. The system (see Figure 1) is based on a concept of (1) initially modulating the laser frequency to sweep it through a spectral range that includes the desired absorption peak, (2) determining the derivative of the absorption peak with respect to the laser frequency for use as an error signal, (3) identifying the desired frequency [at the very top (which is also the middle) of the peak] as the frequency where the derivative goes to zero, and (4) thereafter keeping the frequency within a locking range and adjusting the frequency as needed to keep the derivative (the error signal) as close as possible to zero. More specifically, the system utilizes the fact that in addition to a zero crossing at the top of the absorption peak, the error signal also closely approximates a straight line in the vicinity of the zero crossing (see Figure 2). This vicinity is the locking range because the linearity of the error signal in this range makes it useful as a source of feedback for a proportional + integral + derivative control scheme that

  12. Photon absorption potential coefficient as a tool for materials engineering

    NASA Astrophysics Data System (ADS)

    Akande, Raphael Oluwole; Oyewande, Emmanuel Oluwole

    2016-09-01

    Different atoms achieve ionizations at different energies. Therefore, atoms are characterized by different responses to photon absorption in this study. That means there exists a coefficient for their potential for photon absorption from a photon source. In this study, we consider the manner in which molecular constituents (atoms) absorb photon from a photon source. We observe that there seems to be a common pattern of variation in the absorption of photon among the electrons in all atoms on the periodic table. We assume that the electrons closest to the nucleus (En) and the electrons closest to the outside of the atom (Eo) do not have as much potential for photon absorption as the electrons at the middle of the atom (Em). The explanation we give to this effect is that the En electrons are embedded within the nuclear influence, and similarly, Eo electrons are embedded within the influence of energies outside the atom that there exists a low potential for photon absorption for them. Unlike En and Eo, Em electrons are conditioned, such that there is a quest for balance between being influenced either by the nuclear force or forces external to the atom. Therefore, there exists a higher potential for photon absorption for Em electrons than for En and Eo electrons. The results of our derivations and analysis always produce a bell-shaped curve, instead of an increasing curve as in the ionization energies, for all elements in the periodic table. We obtained a huge data of PAPC for each of the several materials considered. The point at which two or more PAPC values cross one another is termed to be a region of conflicting order of ionization, where all the atoms absorb equal portion of the photon source at the same time. At this point, a greater fraction of the photon source is pumped into the material which could lead to an explosive response from the material. In fact, an unimaginable and unreported phenomenon (in physics) could occur, when two or more PAPCs cross, and

  13. Carbon dioxide laser absorption spectra of toxic industrial compounds.

    PubMed

    Loper, G L; Sasaki, G R; Stamps, M A

    1982-05-01

    CO(2) laser absorption cross-section data are reported for acrolein, styrene, ethyl acrylate, trichloroethylene, vinyl bromide, and vinylidene chloride. These data indicate that sub parts per billion level, interference-free detection limits should be possible for these compounds by the CO(2) laser photoacoustic technique. Photoacoustic detectabilities below 40 ppb should be possible for these compounds in the presence of ambient air concentrations of water vapor and other anticipated interferences. These compounds are also found not to be important interferences in the detection of toxic hydrazine-based rocket fuels by CO(2) laser spectroscopic techniques.

  14. Remark on: the neutron spherical optical-model absorption.

    SciTech Connect

    Smith, A. B.; Nuclear Engineering Division

    2007-06-30

    The energy-dependent behavior of the absorption term of the spherical neutron optical potential for doubly magic {sup 208}Pb and the neighboring {sup 209}Bi is examined. These considerations suggest a phenomenological model that results in an intuitively attractive energy dependence of the imaginary potential that provides a good description of the observed neutron cross sections and that is qualitatively consistent with theoretical concepts. At the same time it provides an alternative to some of the arbitrary assumptions involved in many conventional optical-model interpretations reported in the literature and reduces the number of the parameters of the model.

  15. Glucagon receptor antagonism induces increased cholesterol absorption[S

    PubMed Central

    Guan, Hong-Ping; Yang, Xiaodong; Lu, Ku; Wang, Sheng-Ping; Castro-Perez, Jose M.; Previs, Stephen; Wright, Michael; Shah, Vinit; Herath, Kithsiri; Xie, Dan; Szeto, Daphne; Forrest, Gail; Xiao, Jing Chen; Palyha, Oksana; Sun, Li-Ping; Andryuk, Paula J.; Engel, Samuel S.; Xiong, Yusheng; Lin, Songnian; Kelley, David E.; Erion, Mark D.; Davis, Harry R.; Wang, Liangsu

    2015-01-01

    Glucagon and insulin have opposing action in governing glucose homeostasis. In type 2 diabetes mellitus (T2DM), plasma glucagon is characteristically elevated, contributing to increased gluconeogenesis and hyperglycemia. Therefore, glucagon receptor (GCGR) antagonism has been proposed as a pharmacologic approach to treat T2DM. In support of this concept, a potent small-molecule GCGR antagonist (GRA), MK-0893, demonstrated dose-dependent efficacy to reduce hyperglycemia, with an HbA1c reduction of 1.5% at the 80 mg dose for 12 weeks in T2DM. However, GRA treatment was associated with dose-dependent elevation of plasma LDL-cholesterol (LDL-c). The current studies investigated the cause for increased LDL-c. We report findings that link MK-0893 with increased glucagon-like peptide 2 and cholesterol absorption. There was not, however, a GRA-related modulation of cholesterol synthesis. These findings were replicated using structurally diverse GRAs. To examine potential pharmacologic mitigation, coadministration of ezetimibe (a potent inhibitor of cholesterol absorption) in mice abrogated the GRA-associated increase of LDL-c. Although the molecular mechanism is unknown, our results provide a novel finding by which glucagon and, hence, GCGR antagonism govern cholesterol metabolism. PMID:26373568

  16. Advanced regenerative absorption refrigeration cycles

    DOEpatents

    Dao, Kim

    1990-01-01

    Multi-effect regenerative absorption cycles which provide a high coefficient of performance (COP) at relatively high input temperatures. An absorber-coupled double-effect regenerative cycle (ADR cycle) (10) is provided having a single-effect absorption cycle (SEA cycle) (11) as a topping subcycle and a single-effect regenerative absorption cycle (1R cycle) (12) as a bottoming subcycle. The SEA cycle (11) includes a boiler (13), a condenser (21), an expansion device (28), an evaporator (31), and an absorber (40), all operatively connected together. The 1R cycle (12) includes a multistage boiler (48), a multi-stage resorber (51), a multisection regenerator (49) and also uses the condenser (21), expansion device (28) and evaporator (31) of the SEA topping subcycle (11), all operatively connected together. External heat is applied to the SEA boiler (13) for operation up to about 500 degrees F., with most of the high pressure vapor going to the condenser (21) and evaporator (31) being generated by the regenerator (49). The substantially adiabatic and isothermal functioning of the SER subcycle (12) provides a high COP. For higher input temperatures of up to 700 degrees F., another SEA cycle (111) is used as a topping subcycle, with the absorber (140) of the topping subcycle being heat coupled to the boiler (13) of an ADR cycle (10). The 1R cycle (12) itself is an improvement in that all resorber stages (50b-f) have a portion of their output pumped to boiling conduits (71a-f) through the regenerator (49), which conduits are connected to and at the same pressure as the highest pressure stage (48a) of the 1R multistage boiler (48).

  17. Interstellar dust grain composition from high-resolution X-ray absorption edge structure

    NASA Astrophysics Data System (ADS)

    Corrales, Lia

    2016-06-01

    X-ray light is sufficient to excite electrons from n=1 (K-shell) and n=2 (L-shell) energy levels of neutral interstellar metals, causing a sharp increase in the absorption cross-section. Near the ionization energy, the shape of the photoelectric absorption edge depends strongly on whether the atom is isolated or bound in molecules or minerals (dust). With high resolution X-ray spectroscopy, we can directly measure the state of metals and the mineral composition of dust in the interstellar medium. In addition, the scattering contribution to the X-ray extinction cross-section can be used to gauge grain size, shape, and filling factor. In order to fully take advantage of major advances in high resolution X-ray spectroscopy, lab measurements of X-ray absorption fine structure (XAFS) from suspected interstellar minerals are required. Optical constants derived from the absorption measurements can be used with Mie scattering or anomalous diffraction theory in order to model the full extinction cross-sections from the interstellar medium. Much like quasar spectra are used to probe other intergalactic gas, absorption spectroscopy of Galactic X-ray binaries and bright stars will yield key insights to the mineralogy and evolution of dust grains in the Milky Way.

  18. Energy Absorption of Composite Materials.

    DTIC Science & Technology

    1983-03-01

    34 tion in a helicopter crash is accomplished Foye , et al. [4 an 5] examlnei th, primarily through three mechanisms; strok- energy absorption chara"tr...irar [3] and Foye , et al. [4]. No significant o. ’, energy release was obse:’viV-cirur, i m: rcg . . the Gr/FE tubes s .. 0T Fu!.A 4r /-e 45rK r5 1...K/E, GI/E, hybrid com- posite tubes and aluminum tubes. The 5. R. L. Foye , and W. T. H,.dg, " r following statements are based on results Results from

  19. Carbon Dioxide Absorption Heat Pump

    NASA Technical Reports Server (NTRS)

    Jones, Jack A. (Inventor)

    2002-01-01

    A carbon dioxide absorption heat pump cycle is disclosed using a high pressure stage and a super-critical cooling stage to provide a non-toxic system. Using carbon dioxide gas as the working fluid in the system, the present invention desorbs the CO2 from an absorbent and cools the gas in the super-critical state to deliver heat thereby. The cooled CO2 gas is then expanded thereby providing cooling and is returned to an absorber for further cycling. Strategic use of heat exchangers can increase the efficiency and performance of the system.

  20. NEUTRON ABSORPTION AND SHIELDING DEVICE

    DOEpatents

    Axelrad, I.R.

    1960-06-21

    A neutron absorption and shielding device is described which is adapted for mounting in a radiation shielding wall surrounding a radioactive area through which instrumentation leads and the like may safely pass without permitting gamma or neutron radiation to pass to the exterior. The shielding device comprises a container having at least one nonrectilinear tube or passageway means extending therethrough, which is adapted to contain instrumentation leads or the like, a layer of a substance capable of absorbing gamma rays, and a solid resinous composition adapted to attenuate fast-moving neutrons and capture slow- moving or thermal neutrons.

  1. Large excited state two photon absorptions in the near infrared region of surprisingly stable radical cations of (ferrocenyl)indenes.

    PubMed

    Orian, Laura; Scuppa, Stefano; Santi, Saverio; Meneghetti, Moreno

    2013-08-21

    Multiphoton absorptions are important non-linear optical processes which allow us to explore excited states with low energy photons giving rise to new possibilities for photoinduced processes. Among these processes, multiphoton absorptions from excited states are particularly interesting because of the large susceptibilities characteristic of excited states. Here we explore the nonlinear transmission measurements recorded with 9 ns laser pulses at 1064 nm of the radical cations of (2-ferrocenyl)indene and of (2-ferrocenyl)-hexamethylindene, two interesting very stable molecules. The non-linear transmission data can be interpreted with a multiphoton sequence of three photon absorptions, the first being a one photon absorption related to the intramolecular charge transfer and the second a two photon absorption from the excited state created with the first process. The two photon absorption cross section is found to be several orders of magnitude larger than those usually found for two photon absorbing systems excited from the ground state.

  2. [Kinetics of Cu crossing human erythrocyte membrane].

    PubMed

    Dun, Zhu Ci Ren

    2014-12-01

    This study was aimed to investigate various factors influencing the proceduction of Cu(II) crossing human erythrocyte membrane, including concentration of Cu²⁺, pH value of the medium, temperature and time of incubation, and to derive kinetic equation of Cu(II) crossing human erythrocyte membrane. Suspension red blood cells were incubated by Cu²⁺, then content of Cu²⁺ crossed human erythrocyte membrane was determined by atomic absorption spectrometry under various conditions after digestion. The results showed that content of Cu²⁺ crossed human erythrocyte membrane increased with the increase of extracellular Cu²⁺ and enhancement of incubation temperature, and the content of Cu²⁺ crossed human erythrocyte membrane showed a increasing tendency when pH reached to 6.2-7.4, and to maximum at pH 7.4, then gradually decreased at range of pH 7.4-9.2. It is concluded that the Cu²⁺ crossing human erythrocyte has been confirmed to be the first order kinetics characteristics within 120 min, and the linear equation is 10³ × Y = 0.0497t +6.5992.

  3. Tunneling induced absorption with competing Nonlinearities

    PubMed Central

    Peng, Yandong; Yang, Aihong; Xu, Yan; Wang, Peng; Yu, Yang; Guo, Hongju; Ren, Tingqi

    2016-01-01

    We investigate tunneling induced nonlinear absorption phenomena in a coupled quantum-dot system. Resonant tunneling causes constructive interference in the nonlinear absorption that leads to an increase of more than an order of magnitude over the maximum absorption in a coupled quantum dot system without tunneling. Resonant tunneling also leads to a narrowing of the linewidth of the absorption peak to a sublinewidth level. Analytical expressions show that the enhanced nonlinear absorption is largely due to the fifth-order nonlinear term. Competition between third- and fifth-order nonlinearities leads to an anomalous dispersion of the total susceptibility. PMID:27958303

  4. Absorption of CO laser radiation by NO

    NASA Technical Reports Server (NTRS)

    Hanson, R. K.; Monat, J. P.; Kruger, C. H.

    1976-01-01

    The paper describes absorption calculations and measurements at selected infrared CO laser wavelengths which are nearly coincident with absorption lines in the fundamental vibration-rotation band of NO near 5.3 microns. Initial work was directed towards establishing the optimal CO laser-NO absorption line coincidence for high temperature applications. Measurements of the absorption coefficient at this optimal laser wavelength were carried out, first using a room-temperature absorption cell for high-temperature calculations and then using a shock tube, for the temperature range 630-4000 K, to validate the high temperature calculations.

  5. Two-photon absorption of Zn(II) octupolar molecules.

    PubMed

    Mazzucato, Simone; Fortunati, Ilaria; Scolaro, Sara; Zerbetto, Michele; Ferrante, Camilla; Signorini, Raffaella; Pedron, Danilo; Bozio, Renato; Locatelli, Danika; Righetto, Stefania; Roberto, Dominique; Ugo, Renato; Abbotto, Alessandro; Archetti, Graziano; Beverina, Luca; Ghezzi, Sergio

    2007-06-21

    In this work we present an investigation of the non-linear optical (NLO) properties of two octupolar chromophores: [Zn(4,4'-bis(dibutylaminostyryl)-[2,2']-bipyridine)(3)](2+) and [Zn(4,4'-bis((E)-2-(N-(TEG)pyrrol-2-yl)vinyl)-[2,2']-bipyridine)(3)](2+) with Zn(ii) as the coordination center, using two-photon emission technique (TPE) in fs-pulse temporal regime. Compared to the free ligands, our results do not show a net increase in the two-photon absorption (TPA) cross-section for the octupolar complexes, once normalized to the ligand unit. This is in partial disagreement with a previous theoretical study investigating the first molecule where a significant increase of the TPA cross-section was predicted (X. J. Liu, et al., J. Chem. Phys., 2004, 120, 11 493).

  6. Pion absorption on Xenon in the region of the delta(1232) resonance

    NASA Astrophysics Data System (ADS)

    Gregory, Nikolas Kellogg

    The absorption of π+ mesons at 118, 162, and 239 MeV on Xenon has been studied using the Large Acceptance Detector System (LADS) at the Paul Scherrer Institute in Villigen, Switzerland. LADS has a solid angle coverage of over 98% of 4π steradians and an energy threshold of less than 20 MeV for protons, making it an excellent detector for studying multi- nucleon final states following π+/- absorption. The total absorption cross sections at the three energies are, in millibarns: 602 +/- 140, 772 +/- 150, and 668 +/- 70. In addition, the breakup of the cross section into channels with different numbers of energetic final state nucleons has been determined. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253- 1690.)

  7. Stable high absorption metamaterial for wide-angle incidence of terahertz wave

    NASA Astrophysics Data System (ADS)

    Du, Qiujiao; Zeng, Zuoxun; Xiang, Dong; Lv, Tao; Zhang, Guangyong; Yang, Hongwu

    2014-04-01

    We propose a metamaterial based on metallic Jerusalem cross and cross-wire structures for realizing relatively stable high absorption with respect to the wide angle incidence of both polarized terahertz (THz) waves. Numerical simulations are carried out to verify the proposed absorber. For both transverse electric and transverse magnetic polarizations, absorptions around 0.93 THz reach nearly up to unity under normal incidence and maintain above 97% over a wide incidence angle range. The THz absorber can be easily micro-fabricated due to a thickness about 40 times smaller than operating wavelength. The proposed metamaterial is a promising candidate as absorbing element in THz thermal imager, due to its wide angle, stable high absorption and very thin thickness.

  8. Sulphate absorption across biological membranes.

    PubMed

    Mitchell, Stephen C; Waring, Rosemary H

    2016-01-01

    1. Sulphonation is unusual amongst the common Phase II (condensation; synthetic) reactions experienced by xenobiotics, in that the availability of the conjugating agent, sulphate, may become a rate-limiting factor. This sulphate is derived within the body via the oxygenation of sulphur moieties liberated from numerous ingested compounds including the sulphur-containing amino acids. Preformed inorganic sulphate also makes a considerable contribution to this pool. 2. There has been a divergence of opinion as to whether or not inorganic sulphate may be readily absorbed from the gastrointestinal tract and this controversy still continues in some quarters. Even more so, is the vexing question of potential absorption of inorganic sulphate via the lungs and through the skin. 3. This review examines the relevant diverse literature and concludes that sulphate ions may move across biological membranes by means of specific transporters and, although the gastrointestinal tract is by far the major portal of entry, some absorption across the lungs and the skin may take place under appropriate circumstances.

  9. Formaldehyde Absorption toward W51

    SciTech Connect

    Kogut, A.; Smoot, G.F.; Bennett, C.L.; Petuchowski, S.J.

    1988-04-01

    We have measured formaldehyde (H{sub 2}CO) absorption toward the HII region complex W51A (G49.5-0.4) in the 6 cm and 2 cm wavelength rotational transitions with angular resolution of approximately 4 inch. The continuum HII region shows a large, previously undetected shell structure 5.5 pc along the major axis. We observe no H{sub 2}CO emission in regions of low continuum intensity. The absorption, converted to optical depth, shows a higher degree of clumping than previous maps at lower resolution. The good S/N of the maps allows accurate estimation of the complicated line profiles, showing some of the absorbing clouds to be quite patchy. We list the properties of the opacity spectra for a number of positions both in the clumps and in the more diffuse regions of the absorbing clouds, and derive column densities for the 1{sub 11} and 2{sub 12} rotational levels of ortho-formaldehyde.

  10. QED-driven laser absorption

    NASA Astrophysics Data System (ADS)

    Levy, Matthew; Blackburn, T.; Ratan, N.; Sadler, J.; Ridgers, C.; Kasim, M.; Ceurvorst, L.; Holloway, J.; Baring, M.; Bell, A.; Glenzer, S.; Gregori, G.; Ilderton, A.; Marklund, M.; Tabak, M.; Wilks, S.; Norreys, P.

    2016-10-01

    Absorption covers the physical processes which convert intense photon flux into energetic particles when a high-power laser (I >1018 W cm-2 where I is intensity at 1 μm wavelength) illuminates optically-thick matter. It underpins important applications of petawatt laser systems today, e.g., in isochoric heating of materials. Next-generation lasers such as ELI are anticipated to produce quantum electrodynamical (QED) bursts of γ-rays and anti-matter via the multiphoton Breit-Wheeler process which could enable scaled laboratory probes, e.g., of black hole winds. Here, applying strong-field QED to advances in plasma kinematic theory, we present a model elucidating absorption limited only by an avalanche of self-created electron-positron pairs at ultra-high-field. The model, confirmed by multidimensional QED-PIC simulations, works over six orders of magnitude in optical intensity and reveals this cascade is initiated at 1.8 x 1025 W cm-2 using a realistic linearly-polarized laser pulse. Here the laser couples its energy into highly-collimated electrons, ions, γ-rays, and positrons at 12%, 6%, 58% and 13% efficiency, respectively. We remark on attributes of the QED plasma state and possible applications.

  11. Iodine Absorption Cells Purity Testing

    PubMed Central

    Hrabina, Jan; Zucco, Massimo; Philippe, Charles; Pham, Tuan Minh; Holá, Miroslava; Acef, Ouali; Lazar, Josef; Číp, Ondřej

    2017-01-01

    This article deals with the evaluation of the chemical purity of iodine-filled absorption cells and the optical frequency references used for the frequency locking of laser standards. We summarize the recent trends and progress in absorption cell technology and we focus on methods for iodine cell purity testing. We compare two independent experimental systems based on the laser-induced fluorescence method, showing an improvement of measurement uncertainty by introducing a compensation system reducing unwanted influences. We show the advantages of this technique, which is relatively simple and does not require extensive hardware equipment. As an alternative to the traditionally used methods we propose an approach of hyperfine transitions’ spectral linewidth measurement. The key characteristic of this method is demonstrated on a set of testing iodine cells. The relationship between laser-induced fluorescence and transition linewidth methods will be presented as well as a summary of the advantages and disadvantages of the proposed technique (in comparison with traditional measurement approaches). PMID:28067834

  12. Iron Absorption in Drosophila melanogaster

    PubMed Central

    Mandilaras, Konstantinos; Pathmanathan, Tharse; Missirlis, Fanis

    2013-01-01

    The way in which Drosophila melanogaster acquires iron from the diet remains poorly understood despite iron absorption being of vital significance for larval growth. To describe the process of organismal iron absorption, consideration needs to be given to cellular iron import, storage, export and how intestinal epithelial cells sense and respond to iron availability. Here we review studies on the Divalent Metal Transporter-1 homolog Malvolio (iron import), the recent discovery that Multicopper Oxidase-1 has ferroxidase activity (iron export) and the role of ferritin in the process of iron acquisition (iron storage). We also describe what is known about iron regulation in insect cells. We then draw upon knowledge from mammalian iron homeostasis to identify candidate genes in flies. Questions arise from the lack of conservation in Drosophila for key mammalian players, such as ferroportin, hepcidin and all the components of the hemochromatosis-related pathway. Drosophila and other insects also lack erythropoiesis. Thus, systemic iron regulation is likely to be conveyed by different signaling pathways and tissue requirements. The significance of regulating intestinal iron uptake is inferred from reports linking Drosophila developmental, immune, heat-shock and behavioral responses to iron sequestration. PMID:23686013

  13. Iron absorption in Drosophila melanogaster.

    PubMed

    Mandilaras, Konstantinos; Pathmanathan, Tharse; Missirlis, Fanis

    2013-05-17

    The way in which Drosophila melanogaster acquires iron from the diet remains poorly understood despite iron absorption being of vital significance for larval growth. To describe the process of organismal iron absorption, consideration needs to be given to cellular iron import, storage, export and how intestinal epithelial cells sense and respond to iron availability. Here we review studies on the Divalent Metal Transporter-1 homolog Malvolio (iron import), the recent discovery that Multicopper Oxidase-1 has ferroxidase activity (iron export) and the role of ferritin in the process of iron acquisition (iron storage). We also describe what is known about iron regulation in insect cells. We then draw upon knowledge from mammalian iron homeostasis to identify candidate genes in flies. Questions arise from the lack of conservation in Drosophila for key mammalian players, such as ferroportin, hepcidin and all the components of the hemochromatosis-related pathway. Drosophila and other insects also lack erythropoiesis. Thus, systemic iron regulation is likely to be conveyed by different signaling pathways and tissue requirements. The significance of regulating intestinal iron uptake is inferred from reports linking Drosophila developmental, immune, heat-shock and behavioral responses to iron sequestration.

  14. Absorption in Extended Inhomogeneous Clouds

    NASA Technical Reports Server (NTRS)

    Joiner, Joanna; Vasilkov, Alexander; Spurr, Robert; Bhartia, P. K.; Krotkov, Nick

    2008-01-01

    The launch of several different sensors, including CloudSat, into the A-train constellation of satellites allows us for the first time to compute absorption that can occur in realistic vertically inhomogeneous clouds including multiple cloud decks. CloudSat data show that these situations are common. Therefore, understanding vertically inhomogeneous clouds is important from both climate and satellite atmospheric composition remote sensing perspectives. Satellite passive sensors that operate from the near IR to the UV often rely on radiative cloud pressures derived from absorption in oxygen bands (A, B, gamma, or O2-O2 bands) or from rotational-Raman scattering in order to retrieve information about atmospheric trace gases. The radiative cloud pressure is distinct from the physical cloud top derived from thermal infrared measurements. Therefore, the combination of information from different passive sensors yields some information about the cloud vertical profile. When either or both the clouds or atmospheric absorbers (trace gases and aerosols) are vertically inhomogeneous, the use of an effective cloud pressure derived from these approaches may lead to errors. Here, we focus on several scenarios (deep convective clouds and distinct two layer clouds) based on realistic cloud optical depth vertical profiles derived from the CloudSatfMODIS combination. We focus on implications for trace-gas column amount retrievals (specifically ozone and NO2) and derived surface UV irradiance from the Ozone Monitoring Instrument (OMI) on the Atrain Aura platform.

  15. Energy absorption of composite materials

    NASA Technical Reports Server (NTRS)

    Farley, G. L.

    1983-01-01

    Results of a study on the energy absorption characteristics of selected composite material systems are presented and the results compared with aluminum. Composite compression tube specimens were fabricated with both tape and woven fabric prepreg using graphite/epoxy (Gr/E), Kevlar (TM)/epoxy (K/E) and glass/epoxy (Gl/E). Chamfering and notching one end of the composite tube specimen reduced the peak load at initial failure without altering the sustained crushing load, and prevented catastrophic failure. Static compression and vertical impact tests were performed on 128 tubes. The results varied significantly as a function of material type and ply orientation. In general, the Gr/E tubes absorbed more energy than the Gl/E or K/E tubes for the same ply orientation. The 0/ + or - 15 Gr/E tubes absorbed more energy than the aluminum tubes. Gr/E and Gl/E tubes failed in a brittle mode and had negligible post crushing integrity, whereas the K/E tubes failed in an accordian buckling mode similar to the aluminum tubes. The energy absorption and post crushing integrity of hybrid composite tubes were not significantly better than that of the single material tubes.

  16. Pion absorption on 3He at Tπ=62.5 and 82.8 MeV

    NASA Astrophysics Data System (ADS)

    Aniol, K. A.; Altman, A.; Johnson, R. R.; Roser, H. W.; Tacik, R.; Wienands, U.; Ashery, D.; Alster, J.; Moinester, M. A.; Piasetzky, E.; Gill, D. R.; Vincent, J.

    1986-05-01

    Pion absorption in 3He was studied at Tπ=62.5 and 82.8 MeV using nucleon-nucleon coincidences. For π+ absorption on proton-neutron pairs the differential cross section is the same as that for π++d-->p+p except for an increase by a factor of about 1.5. For π- absorption on the proton-proton pair, the differential cross section is asymmetric about 90°, indicating possible isospin mixing. The total cross sections σpn(π+) are 10.2+/-0.9 mb and 13.5+/-1.3 mb at 62.5 and 82.8 MeV and for σpp(π-) are 0.70+/-0.07 mb and 0.92+/-0.10 mb at 62.5 and 82.8 MeV. The three-body absorption cross sections for π+ and π- are found to be comparable to each other and show no strong energy dependence. The three-body absorption cross section σ3(π+) is 6.7+/-2.5 mb and 5.7+/-2.3 mb and for π-, σ3(π-) is 8.7+/-1.4 mb and 6.5+/-2.0 mb at 62.5 and 82.8 MeV, respectively.

  17. Atomic form factors and photoelectric absorption cross-sections near absorption edges in the soft X-ray region

    SciTech Connect

    Chantler, C.

    2006-11-09

    Reliable knowledge of the complex X-ray form factor [Re(f) and Im(f)] and the photoelectric attenuation coefficient ({delta}{sub PE}) is required for crystallography, medical diagnosis, radiation safety and XAFS studies. Key discrepancies in earlier theoretical work are due to the smoothing of edge structure, the use of non-relativistic wave functions, and the lack of appropriate convergence of wave functions. These discrepancies lead to significant corrections for most comprehensive (i.e. all-Z) tabulations. This work has led to a major comprehensive database tabulation [Chantler, C. T. (2000). J. Phys. Chem. Ref. Data, 29, 597-1048] which serves as a sequel and companion to earlier relativistic Dirac-Fock computations [Chantler, C. T. (1995). J. Phys. Chem. Ref. Data, 24, 71-643]. The paper finds that earlier work needs improvement in the near-edge region for soft X-ray energies, and derives new theoretical results of substantially higher accuracy in near-edge soft X-ray regions. Fine grids near edges are tabulated demonstrating the current comparison with alternate theory and with available experimental data. The best experimental data and the observed experimental structure as a function of energy are strong indicators of the validity of the current approach. New developments in experimental measurement hold great promise in making critical comparisons with theory in the near future.

  18. Atomic form factors and photoelectric absorption cross-sections near absorption edges in the soft X-ray region

    SciTech Connect

    Chantler, C.T.

    2003-01-24

    Reliable knowledge of the complex X-ray form factor [Re(f) and Im(f)] and the photoelectric attenuation coefficient ({sigma}PE) is required for crystallography, medical diagnosis, radiation safety and XAFS studies. Key discrepancies in earlier theoretical work are due to the smoothing of edge structure, the use of non-relativistic wave functions, and the lack of appropriate convergence of wave functions. These discrepancies lead to significant corrections for most comprehensive (i.e. all-Z) tabulations. This work has led to a major comprehensive database tabulation [Chantler, C. T. (2000). J. Phys. Chem. Ref. Data, 29, 597-1048] which serves as a sequel and companion to earlier relativistic Dirac-Fock computations [Chantler, C. T. (1995). J. Phys. Chem. Ref. Data, 24, 71-643]. The paper finds that earlier work needs improvement in the near-edge region for soft X-ray energies, and derives new theoretical results of substantially higher accuracy in near-edge soft X-ray regions. Fine grids near edges are tabulated demonstrating the current comparison with alternate theory and with available experimental data. The best experimental data and the observed experimental structure as a function of energy are strong indicators of the validity of the current approach. New developments in experimental measurement hold great promise in making critical comparisons with theory in the near future. This work forms the latest component of the FFAST NIST database [http://physics.nist.gov/PhysRefData/FFast02/Text/cover.html].

  19. Two-photon absorption in oxazole derivatives: An experimental and quantum chemical study

    NASA Astrophysics Data System (ADS)

    Silva, D. L.; De Boni, L.; Correa, D. S.; Costa, S. C. S.; Hidalgo, A. A.; Zilio, S. C.; Canuto, S.; Mendonca, C. R.

    2012-05-01

    Experimental and theoretical studies on the two-photon absorption properties of two oxazole derivatives: 2,5-diphenyloxazole (PPO) and 2-(4-biphenylyl)-5-phenyl-1,3,4-oxadiazole (PBD) are presented. The two-photon absorption cross-section spectra were determined by means of the Z-scan technique, from 460 up to 650 nm, and reached peak values of 84 GM for PBD and 27 GM for PPO. Density Functional Theory and response function formalism are used to determine the molecular structures and the one- and two-photon absorption properties and to assist in the interpretation of the experimental results. The Polarizable Continuum Model in one-photon absorption calculations is used to estimate solvent effects.

  20. Assessing the absorption of new pharmaceuticals.

    PubMed

    Hidalgo, I J

    2001-11-01

    The advent of more efficient methods to synthesize and screen new chemical compounds is increasing the number of chemical leads identified in the drug discovery phase. Compounds with good biological activity may fail to become drugs due to insufficient oral absorption. Selection of drug development candidates with adequate absorption characteristics should increase the probability of success in the development phase. To assess the absorption potential of new chemical entities numerous in vitro and in vivo model systems have been used. Many laboratories rely on cell culture models of intestinal permeability such as, Caco-2, HT-29 and MDCK. To attempt to increase the throughput of permeability measurements, several physicochemical methods such as, immobilized artificial membrane (IAM) columns and parallel artificial membrane permeation assay (PAMPA) have been used. More recently, much attention has been given to the development of computational methods to predict drug absorption. However, it is clear that no single method will sufficient for studying drug absorption, but most likely a combination of systems will be needed. Higher throughput, less reliable methods could be used to discover 'loser' compounds, whereas lower throughput, more accurate methods could be used to optimize the absorption properties of lead compounds. Finally, accurate methods are needed to understand absorption mechanisms (efflux-limited absorption, carrier-mediated, intestinal metabolism) that may limit intestinal drug absorption. This information could be extremely valuable to medicinal chemists in the selection of favorable chemo-types. This review describes different techniques used for evaluating drug absorption and indicates their advantages and disadvantages.

  1. Cross-functional systems

    NASA Technical Reports Server (NTRS)

    Lee, Mark

    1991-01-01

    Many companies, including Xerox and Texas Instruments, are using cross functional systems to deal with the increasingly complex and competitive business environment. However, few firms within the aerospace industry appear to be aware of the significant benefits that cross functional systems can provide. Those benefits are examined and a flexible methodology is discussed that companies can use to identify and develop cross functional systems that will help improve organizational performance. In addition, some of the managerial issues are addressed that cross functional systems may raise and specific examples are used to explore networking's contributions to cross functional systems.

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

    NASA Astrophysics Data System (ADS)

    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 × 104 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.

  3. Optical microresonators as single-particle absorption spectrometers

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

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

  4. Transient absorption spectra of the laser-dressed hydrogen atom

    NASA Astrophysics Data System (ADS)

    Murakami, Mitsuko; Chu, Shih-I.

    2013-10-01

    We present a theoretical study of transient absorption spectra of laser-dressed hydrogen atoms, based on numerical solutions of the time-dependent Schrödinger equation. The timing of absorption is controlled by the delay between an extreme ultra violet (XUV) pulse and an infrared (IR) laser field. The XUV pulse is isolated and several hundred attoseconds in duration, which acts as a pump to drive the ground-state electron to excited p states. The subsequent interaction with the IR field produces dressed states, which manifest as sidebands between the 1s-np absorption spectra separated by one IR-photon energy. We demonstrate that the population of dressed states is maximized when the timing of the XUV pulse coincides with the zero crossing of the IR field, and that their energies can be manipulated in a subcycle time scale by adding a chirp to the IR field. An alternative perspective to the problem is to think of the XUV pulse as a probe to detect the dynamical ac Stark shifts. Our results indicate that the accidental degeneracy of the hydrogen excited states is removed while they are dressed by the IR field, leading to large ac Stark shifts. Furthermore, we observe the Autler-Townes doublets for the n=2 and 3 levels using the 656 nm dressing field, but their separation does not agree with the prediction by the conventional three-level model that neglects the dynamical ac Stark shifts.

  5. High Velocity Absorption during Eta Car B's Periastron Passage

    NASA Technical Reports Server (NTRS)

    Nielsen, Krister E.; Groh, J. H.; Hillier, J.; Gull, Theodore R.; Owocki, S. P.; Okazaki, A. T.; Damineli, A.; Teodoro, M.; Weigelt, G.; Hartman, H.

    2010-01-01

    Eta Car is one of the most luminous massive stars in the Galaxy, with repeated eruptions with a 5.5 year periodicity. These events are caused by the periastron passage of a massive companion in an eccentric orbit. We report the VLT/CRIRES detection of a strong high-velocity, (<1900 km/s) , broad absorption wing in He I at 10833 A during the 2009.0 periastron passage. Previous observations during the 2003.5 event have shown evidence of such high-velocity absorption in the He I 10833 transition, allowing us to conclude that the high-velocity gas is crossing the line-of-sight toward Eta Car over a time period of approximately 2 months. Our analysis of HST/STlS archival data with observations of high velocity absorption in the ultraviolet Si IV and C IV resonance lines, confirm the presence of a high-velocity material during the spectroscopic low state. The observations provide direct detection of high-velocity material flowing from the wind-wind collision zone around the binary system, and we discuss the implications of the presence of high-velocity gas in Eta Car during periastron

  6. Computer programs for absorption spectrophotometry.

    PubMed

    Jones, R N

    1969-03-01

    Brief descriptions are given of twenty-two modular computer programs for performing the basic numerical computations of absorption spectrophotometry. The programs, written in Fortran IV for card input and output, are available from the National Research Council of Canada. The input and output formats are standardized to permit easy interfacing to yield more complex data processing systems. Though these programs were developed for ir spectrophotometry, they are readily modified for use with digitized visual and uv spectrophotometers. The operations covered include ordinate and abscissal unit and scale interconversions, ordinate addition and subtraction, location of band maxima and minima, smoothing and differentiation, slit function convolution and deconvolution, band profile analysis and asymmetry quantification, Fourier transformation to time correlation curves, multiple overlapping band separation in terms of Cauchy (Lorentz), Gauss, Cauchy-Gauss product, and Cauchy-Gauss sum functions and cell path length determination from fringe spacing analysis.

  7. Backscatter absorption gas imaging system

    DOEpatents

    McRae, T.G. Jr.

    A video imaging system for detecting hazardous gas leaks. Visual displays of invisible gas clouds are produced by radiation augmentation of the field of view of an imaging device by radiation corresponding to an absorption line of the gas to be detected. The field of view of an imager is irradiated by a laser. The imager receives both backscattered laser light and background radiation. When a detectable gas is present, the backscattered laser light is highly attenuated, producing a region of contrast or shadow on the image. A flying spot imaging system is utilized to synchronously irradiate and scan the area to lower laser power requirements. The imager signal is processed to produce a video display.

  8. Backscatter absorption gas imaging system

    DOEpatents

    McRae, Jr., Thomas G.

    1985-01-01

    A video imaging system for detecting hazardous gas leaks. Visual displays of invisible gas clouds are produced by radiation augmentation of the field of view of an imaging device by radiation corresponding to an absorption line of the gas to be detected. The field of view of an imager is irradiated by a laser. The imager receives both backscattered laser light and background radiation. When a detectable gas is present, the backscattered laser light is highly attenuated, producing a region of contrast or shadow on the image. A flying spot imaging system is utilized to synchronously irradiate and scan the area to lower laser power requirements. The imager signal is processed to produce a video display.

  9. HI Absorption in Merger Remnants

    NASA Technical Reports Server (NTRS)

    Teng, Stacy H.; Veileux, Sylvain; Baker, Andrew J.

    2012-01-01

    It has been proposed that ultraluminous infrared galaxies (ULIRGs) pass through a luminous starburst phase, followed by a dust-enshrouded AGN phase, and finally evolve into optically bright "naked" quasars once they shed their gas/dust reservoirs through powerful wind events. We present the results of our recent 21- cm HI survey of 21 merger remnants with the Green Bank Telescope. These remnants were selected from the QUEST (Quasar/ULIRG Evolution Study) sample of ULIRGs and PG quasars; our targets are all bolometrically dominated by AGN and sample all phases of the proposed ULIRG -> IR-excess quasar -> optical quasar sequence. We explore whether there is an evolutionary connection between ULIRGs and quasars by looking for the occurrence of HI absorption tracing neutral gas outflows; our results will allow us to identify where along the sequence the majority of a merger's gas reservoir is expelled.

  10. Multistage quantum absorption heat pumps

    NASA Astrophysics Data System (ADS)

    Correa, Luis A.

    2014-04-01

    It is well known that heat pumps, while being all limited by the same basic thermodynamic laws, may find realization on systems as "small" and "quantum" as a three-level maser. In order to quantitatively assess how the performance of these devices scales with their size, we design generalized N-dimensional ideal heat pumps by merging N -2 elementary three-level stages. We set them to operate in the absorption chiller mode between given hot and cold baths and study their maximum achievable cooling power and the corresponding efficiency as a function of N. While the efficiency at maximum power is roughly size-independent, the power itself slightly increases with the dimension, quickly saturating to a constant. Thus, interestingly, scaling up autonomous quantum heat pumps does not render a significant enhancement beyond the optimal double-stage configuration.

  11. Multistage quantum absorption heat pumps.

    PubMed

    Correa, Luis A

    2014-04-01

    It is well known that heat pumps, while being all limited by the same basic thermodynamic laws, may find realization on systems as "small" and "quantum" as a three-level maser. In order to quantitatively assess how the performance of these devices scales with their size, we design generalized N-dimensional ideal heat pumps by merging N-2 elementary three-level stages. We set them to operate in the absorption chiller mode between given hot and cold baths and study their maximum achievable cooling power and the corresponding efficiency as a function of N. While the efficiency at maximum power is roughly size-independent, the power itself slightly increases with the dimension, quickly saturating to a constant. Thus, interestingly, scaling up autonomous quantum heat pumps does not render a significant enhancement beyond the optimal double-stage configuration.

  12. Quantum-enhanced absorption refrigerators

    PubMed Central

    Correa, Luis A.; Palao, José P.; Alonso, Daniel; Adesso, Gerardo

    2014-01-01

    Thermodynamics is a branch of science blessed by an unparalleled combination of generality of scope and formal simplicity. Based on few natural assumptions together with the four laws, it sets the boundaries between possible and impossible in macroscopic aggregates of matter. This triggered groundbreaking achievements in physics, chemistry and engineering over the last two centuries. Close analogues of those fundamental laws are now being established at the level of individual quantum systems, thus placing limits on the operation of quantum-mechanical devices. Here we study quantum absorption refrigerators, which are driven by heat rather than external work. We establish thermodynamic performance bounds for these machines and investigate their quantum origin. We also show how those bounds may be pushed beyond what is classically achievable, by suitably tailoring the environmental fluctuations via quantum reservoir engineering techniques. Such superefficient quantum-enhanced cooling realises a promising step towards the technological exploitation of autonomous quantum refrigerators. PMID:24492860

  13. Acoustic Absorption in Porous Materials

    NASA Technical Reports Server (NTRS)

    Kuczmarski, Maria A.; Johnston, James C.

    2011-01-01

    An understanding of both the areas of materials science and acoustics is necessary to successfully develop materials for acoustic absorption applications. This paper presents the basic knowledge and approaches for determining the acoustic performance of porous materials in a manner that will help materials researchers new to this area gain the understanding and skills necessary to make meaningful contributions to this field of study. Beginning with the basics and making as few assumptions as possible, this paper reviews relevant topics in the acoustic performance of porous materials, which are often used to make acoustic bulk absorbers, moving from the physics of sound wave interactions with porous materials to measurement techniques for flow resistivity, characteristic impedance, and wavenumber.

  14. Quantum-enhanced absorption refrigerators

    NASA Astrophysics Data System (ADS)

    Correa, Luis A.; Palao, José P.; Alonso, Daniel; Adesso, Gerardo

    2014-02-01

    Thermodynamics is a branch of science blessed by an unparalleled combination of generality of scope and formal simplicity. Based on few natural assumptions together with the four laws, it sets the boundaries between possible and impossible in macroscopic aggregates of matter. This triggered groundbreaking achievements in physics, chemistry and engineering over the last two centuries. Close analogues of those fundamental laws are now being established at the level of individual quantum systems, thus placing limits on the operation of quantum-mechanical devices. Here we study quantum absorption refrigerators, which are driven by heat rather than external work. We establish thermodynamic performance bounds for these machines and investigate their quantum origin. We also show how those bounds may be pushed beyond what is classically achievable, by suitably tailoring the environmental fluctuations via quantum reservoir engineering techniques. Such superefficient quantum-enhanced cooling realises a promising step towards the technological exploitation of autonomous quantum refrigerators.

  15. Ultrafast absorption of intense x rays by nitrogen molecules

    SciTech Connect

    Buth, Christian; Liu Jicai; Chen, Mau Hsiung; Cryan, James P.; Fang Li; Hoener, Matthias; Berrah, Nora; Glownia, James M.; Coffee, Ryan N.

    2012-06-07

    We devise a theoretical description for the response of nitrogen molecules (N{sub 2}) to ultrashort and intense x rays from the free electron laser Linac Coherent Light Source (LCLS). We set out from a rate-equation description for the x-ray absorption by a nitrogen atom. The equations are formulated using all one-x-ray-photon absorption cross sections and the Auger and radiative decay widths of multiply-ionized nitrogen atoms. Cross sections are obtained with a one-electron theory and decay widths are determined from ab initio computations using the Dirac-Hartree-Slater (DHS) method. We also calculate all binding and transition energies of nitrogen atoms in all charge states with the DHS method as the difference of two self-consistent field (SCF) calculations ({Delta}SCF method). To describe the interaction with N{sub 2}, a detailed investigation of intense x-ray-induced ionization and molecular fragmentation are carried out. As a figure of merit, we calculate ion yields and the average charge state measured in recent experiments at the LCLS. We use a series of phenomenological models of increasing sophistication to unravel the mechanisms of the interaction of x rays with N{sub 2}: a single atom, a symmetric-sharing model, and a fragmentation-matrix model are developed. The role of the formation and decay of single and double core holes, the metastable states of N{sub 2}{sup 2+}, and molecular fragmentation are explained.

  16. Elastic scattering, polarization and absorption of relativistic antiprotons on nuclei

    NASA Astrophysics Data System (ADS)

    Larionov, A. B.; Lenske, H.

    2017-01-01

    We perform Glauber model calculations of the antiproton-nucleus elastic and quasielastic scattering and absorption in the beam momentum range ∼ 0.5 ÷ 10 GeV / c. A good agreement of our calculations with available LEAR data and with earlier Glauber model studies of the p bar A elastic scattering allows us to make predictions at the beam momenta of ∼10 GeV/c, i.e. at the regime of the PANDA experiment at FAIR. The comparison with the proton-nucleus elastic scattering cross sections shows that the diffractive minima are much deeper in the p bar A case due to smaller absolute value of the ratio of the real-to-imaginary part of the elementary elastic amplitude. Significant polarization signal for p bar A elastic scattering at 10 GeV/c is expected. We have also revealed a strong dependence of the p bar A absorption cross section on the slope parameter of the transverse momentum dependence of the elementary p bar N amplitude. The p bar A optical potential is discussed.

  17. Enhanced optical absorption and electric field resonance in diabolo metal bar optical antennas.

    PubMed

    Pan, Zeyu; Guo, Junpeng

    2013-12-30

    Resonance behaviors of the fundamental resonance mode of diabolo metal bar optical antennas are investigated by using finite-difference time-domain (FDTD) numerical simulations and a dipole oscillator model. It is found that as the waist of the diabolo metal bar optical antenna is reduced, optical energy absorption cross section and near field enhancement at resonance increase significantly. Also reduction of the diabolo waist width causes red-shift of the resonant wavelengths in the spectra of absorption cross-section, scattering cross-section, and the near electric field. A dipole oscillator model including the self-inductance force is used to fit the FDTD numerical simulation results. The dipole oscillator model characterizes well the resonance behaviors of narrow waist diabolo metal bar optical antennas.

  18. High sensitivity ultra-broad-band absorption spectroscopy of inductively coupled chlorine plasma

    NASA Astrophysics Data System (ADS)

    Marinov, Daniil; Foucher, Mickaël; Campbell, Ewen; Brouard, Mark; Chabert, Pascal; Booth, Jean-Paul

    2016-06-01

    We propose a method to measure the densities of vibrationally excited Cl2(v) molecules in levels up to v  =  3 in pure chlorine inductively coupled plasmas (ICPs). The absorption continuum of Cl2 in the 250-450 nm spectral range is deconvoluted into the individual components originating from the different vibrational levels of the ground state, using a set of ab initio absorption cross sections. It is shown that gas heating at constant pressure is the major depletion mechanism of the Cl2 feedstock in the plasma. In these line-integrated absorption measurements, the absorption by the hot (and therefore rarefied) Cl2 gas in the reactor centre is masked by the cooler (and therefore denser) Cl2 near the walls. These radial gradients in temperature and density make it difficult to assess the degree of vibrational excitation in the centre of the reactor. The observed line-averaged vibrational distributions, when analyzed taking into account the radial temperature gradient, suggest that vibrational and translational degrees of freedom in the plasma are close to local equilibrium. This can be explained by efficient vibrational-translational (VT) relaxation between Cl2 and Cl atoms. Besides the Cl2(v) absorption band, a weak continuum absorption is observed at shorter wavelengths, and is attributed to photodetachment of Cl- negative ions. Thus, line-integrated densities of negative ions in chlorine plasmas can be directly measured using broad-band absorption spectroscopy.

  19. Modified Sagnac interferometer for contact-free length measurement of a direct absorption cell.

    PubMed

    Elandaloussi, Hadj; Rouillé, Christian; Marie-Jeanne, Patrick; Janssen, Christof

    2016-03-10

    Accurate path length measurements in absorption cells are recurrent requirements in quantitative molecular absorption spectroscopy. A new twin path laser interferometer for length measurements in a simple direct path absorption geometry is presented, along with a full uncertainty budget. The path in an absorption cell is determined by measuring the optical path length change due to the diminution of the refractive index when the cell originally filled with nitrogen gas is evacuated. The performance of the instrument based on a stabilized HeNe laser is verified by comparison with the results of direct mechanical length measurements of a roughly 45 mm long, specially designed absorption cell. Due to a resolution of about 1/300 of a HeNe fringe, an expanded (coverage factor k=2) uncertainty of 16 μm in the length measurement is achieved, providing an expanded relative uncertainty of 3.6·10⁻⁴ for the length of our test absorption cell. This value is about 8 times lower than what has been reported previously. The instrument will be useful for precision measurements of absorption cross sections of strong absorbers which require short light paths, such as ozone, halogen oxides, sulfur dioxide, and volatile organic compounds in the UV.

  20. Time-Resolved Broadband Cavity-Enhanced Absorption Spectroscopy behind Shock Waves.

    PubMed

    Matsugi, Akira; Shiina, Hiroumi; Oguchi, Tatsuo; Takahashi, Kazuo

    2016-04-07

    A fast and sensitive broadband absorption technique for measurements of high-temperature chemical kinetics and spectroscopy has been developed by applying broadband cavity-enhanced absorption spectroscopy (BBCEAS) in a shock tube. The developed method has effective absorption path lengths of 60-200 cm, or cavity enhancement factors of 12-40, over a wavelength range of 280-420 nm, and is capable of simultaneously recording absorption time profiles over an ∼32 nm spectral bandpass in a single experiment with temporal and spectral resolutions of 5 μs and 2 nm, respectively. The accuracy of the kinetic and spectroscopic measurements was examined by investigating high-temperature reactions and absorption spectra of formaldehyde behind reflected shock waves using 1,3,5-trioxane as a precursor. The rate constants obtained for the thermal decomposition reactions of 1,3,5-trioxane (to three formaldehyde molecules) and formaldehyde (to HCO + H) agreed well with the literature data. High-temperature absorption cross sections of formaldehyde between 280 and 410 nm have been determined at the post-reflected-shock temperatures of 955, 1265, and 1708 K. The results demonstrate the applicability of the BBCEAS technique to time- and wavelength-resolved sensitive absorption measurements at high temperatures.

  1. Analysis of frequency dependent pump light absorption

    NASA Astrophysics Data System (ADS)

    Wohlmuth, Matthias; Pflaum, Christoph

    2011-03-01

    Simulations have to accurately model thermal lensing in order to help improving resonator design of diode pumped solid state lasers. To this end, a precise description of the pump light absorption is an important prerequisite. In this paper, we discuss the frequency dependency of the pump light absorption in the laser crystal and its influence on the simulated laser performance. The results show that the pump light absorption has to include the spectral overlap of the emitting pump source and the absorbing laser material. This information can either be used for a fully frequency dependent absorption model or, at least in the shown examples, to compute an effective value for an exponential Beer-Lambert law of absorption. This is particularly significant at pump wavelengths coinciding with a peak of absorption. Consequences for laser stability and performance are analyzed for different pump wavelengths in a Nd:YAG laser.

  2. Studies of cavity enhanced absorption spectroscopy for weak absorption gas measurements

    NASA Astrophysics Data System (ADS)

    Li, Liucheng; Duo, Liping; Gong, Deyu; Ma, Yanhua; Zhang, Zhiguo; Wang, Yuanhu; Zhou, Dongjian; Jin, Yuqi

    2017-01-01

    In order to determine the concentrations of trace amount metastable species in chemical lasers, an off-axis cavity enhanced absorption spectrometer for the detection of weak absorption gases has been built with a noise equivalent absorption sensitivity of 1.6x10-8 cm-1. The absorption spectrum of trace amount gaseous ammonia and water vapor was obtained with a spectral resolution of about 78 MHz. A multiple-line absorption spectroscopic method to determine the temperature of gaseous ammonia has been developed by use of multiple lines of ammonia molecule absorption spectrum.

  3. Atomic absorption spectroscopy in ion channel screening.

    PubMed

    Stankovich, Larisa; Wicks, David; Despotovski, Sasko; Liang, Dong

    2004-10-01

    This article examines the utility of atomic absorption spectroscopy, in conjunction with cold flux assays, to ion channel screening. The multiplicity of ion channels that can be interrogated using cold flux assays and atomic absorption spectroscopy is summarized. The importance of atomic absorption spectroscopy as a screening tool is further elaborated upon by providing examples of the relevance of ion channels to various physiological processes and targeted diseases.

  4. Absorption Coefficient of Alkaline Earth Halides.

    DTIC Science & Technology

    1980-04-01

    levels . As a natural consequence, the magnitude of the absorption coefficient is the key parameter in selecting laser window materials. Over the past...of as can be achieved through improved crystal growing techniques and surface polishing. 2.5. Urbach’s Rule A central question for the development of...high absorption levels , inaccuracies progressively increasing with decreasing absorption level , a natural consequence of decreasing in instrumental

  5. Neural regulation of intestinal nutrient absorption.

    PubMed

    Mourad, Fadi H; Saadé, Nayef E

    2011-10-01

    The nervous system and the gastrointestinal (GI) tract share several common features including reciprocal interconnections and several neurotransmitters and peptides known as gut peptides, neuropeptides or hormones. The processes of digestion, secretion of digestive enzymes and then absorption are regulated by the neuro-endocrine system. Luminal glucose enhances its own absorption through a neuronal reflex that involves capsaicin sensitive primary afferent (CSPA) fibres. Absorbed glucose stimulates insulin release that activates hepatoenteric neural pathways leading to an increase in the expression of glucose transporters. Adrenergic innervation increases glucose absorption through α1 and β receptors and decreases absorption through activation of α2 receptors. The vagus nerve plays an important role in the regulation of diurnal variation in transporter expression and in anticipation to food intake. Vagal CSPAs exert tonic inhibitory effects on amino acid absorption. It also plays an important role in the mediation of the inhibitory effect of intestinal amino acids on their own absorption at the level of proximal or distal segment. However, chronic extrinsic denervation leads to a decrease in intestinal amino acid absorption. Conversely, adrenergic agonists as well as activation of CSPA fibres enhance peptides uptake through the peptide transporter PEPT1. Finally, intestinal innervation plays a minimal role in the absorption of fat digestion products. Intestinal absorption of nutrients is a basic vital mechanism that depends essentially on the function of intestinal mucosa. However, intrinsic and extrinsic neural mechanisms that rely on several redundant loops are involved in immediate and long-term control of the outcome of intestinal function.

  6. Sulphur trioxide absorption apparatus and process

    SciTech Connect

    Cameron, G.M.

    1987-03-31

    This patent describes a contact process for producing a concentrated sulphuric acid from dry sulphur dioxide and oxygen containing mixtures which employs the absorption of sulphur trioxide from a hot, dry gas stream containing sulphur trioxide into at least one sulphuric acid stream. The improvement described here comprises: (a) feeding the gas stream to a lower packed absorption zone contained within an absorption tower; (b) feeding a first sulphuric acid stream to the lower absorption zone to effect absorption of a major portion of the sulphur trioxide from the gas stream into the first sulphuric acid stream to produce a first enriched sulphuric acid stream and a depleted sulphur trioxide gas stream; (c) feeding the depleted sulphur trioxide gas stream to an upper packed absorption zone above the lower absorption zone within the tower; and (d) feeding a second sulphuric acid stream to the upper absorption zone to effect absorption of substantially all of the sulphur trioxide remaining in the depleted sulphur trioxide gas stream to produce a second enriched sulphuric acid stream and a substantially sulphur trioxide-free gas stream.

  7. Study of Evanescence Wave Absorption in Lindane

    NASA Astrophysics Data System (ADS)

    Marzuki, A.; Prasetyo, E.; Gitrin, M. P.; Suryanti, V.

    2017-02-01

    Evanescent wave field has been studied for the purpose of tailoring fiber sensor capable of detecting lindane concentration in a solution. The mounted fiber was optically polished such that part of the fiber clad is stripped off. To study the evanescent wave field absorption in lindane solution, the unclad fiber was immersed in the solution. Light coming out of the fiber was studied at different wavelength each for different lindane concentration. It was shown that evanescent wave field absorption is stronger at wavelength corresponding to lindane absorption band as has been shown from absorption studies lindane in UV-VIS-NIR spectrophotometer.

  8. Terahertz wave absorption via preformed air plasma

    NASA Astrophysics Data System (ADS)

    Zhao, Ji; Zhang, LiangLiang; Wu, Tong; Zhang, CunLin; Zhao, YueJin

    2016-12-01

    Terahertz wave generation from laser-induced air plasma has continued to be an exciting field of research over the course of the past decade. In this paper, we report on an investigation concerning terahertz wave absorption with preformed plasma created by another laser pulse. We examine terahertz absorption behavior by varying the pump power and then analyze the polarization effect of the preplasma beam on terahertz wave absorption. The results of experiments conducted in which a type-I beta barium borate (BBO) crystal is placed before the preformed air plasma indicate that the fundamental (ω) and second harmonic (2ω) pulses can also influence terahertz absorption.

  9. Stratospheric observations of the attenuated solar irradiance in the Schumann-Runge band absorption region of molecular oxygen

    NASA Technical Reports Server (NTRS)

    Frederick, J. E.; Hudson, R. D.; Mentall, J. E.

    1981-01-01

    A spectrometer flown on the first Solar Absorption Balloon Experiment (SABE-1) observed the attenuated solar irradiance between 184 and 202 nm from an altitude near 40 km. These measurements provide a check on the absorption cross sections of molecular oxygen in the spectral region of the Schumann-Runge bands. Comparison of the measurements with calculations based on cross sections derived from laboratory data shows a general agreement although the irradiance measurements have large error bars near the centers of the absorption bands. The results imply that the 184-200 nm solar irradiance that penetrates to the stratosphere can be computed to an accuracy of + or - 30% or better by using presently available cross sections.

  10. Analytical approximations for X-ray cross sections 3

    NASA Astrophysics Data System (ADS)

    Biggs, Frank; Lighthill, Ruth

    1988-08-01

    This report updates our previous work that provided analytical approximations to cross sections for both photoelectric absorption of photons by atoms and incoherent scattering of photons by atoms. This representation is convenient for use in programmable calculators and in computer programs to evaluate these cross sections numerically. The results apply to atoms of atomic numbers between 1 and 100 and for photon energies greater than or equal to 10 eV. The photoelectric cross sections are again approximated by four-term polynomials in reciprocal powers of the photon energy. There are now more fitting intervals, however, than were used previously. The incoherent-scattering cross sections are based on the Klein-Nishina relation, but use simpler approximate equations for efficient computer evaluation. We describe the averaging scheme for applying these atomic results to any composite material. The fitting coefficients are included in tables, and the cross sections are shown graphically.

  11. Omnidirectional and broadband absorption enhancement from trapezoidal Mie resonators in semiconductor metasurfaces

    PubMed Central

    Pala, Ragip A.; Butun, Serkan; Aydin, Koray; Atwater, Harry A.

    2016-01-01

    Light trapping in planar ultrathin-film solar cells is limited due to a small number of optical modes available in the thin-film slab. A nanostructured thin-film design could surpass this limit by providing broadband increase in the local density of states in a subwavelength volume and maintaining efficient coupling of light. Here we report a broadband metasurface design, enabling efficient and broadband absorption enhancement by direct coupling of incoming light to resonant modes of subwavelengthscale Mie nanoresonators defined in the thin-film active layer. Absorption was investigated both theoretically and experimentally in prototypes consisting of lithographically patterned, two-dimensional periodic arrays of silicon nanoresonators on silica substrates. A crossed trapezoid resonator shape of rectangular cross section is used to excite broadband Mie resonances across visible and near-IR spectra. Our numerical simulations, optical absorption measurements and photocurrent spectral response measurements demonstrate that crossed trapezoidal Mie resonant structures enable angle-insensitive, broadband absorption. A short circuit current density of 12.0 mA/cm2 is achieved in 210 nm thick patterned Si films, yielding a 4-fold increase compared to planar films of the same thickness. It is suggested that silicon metasurfaces with Mie resonator arrays can provide useful insights to guide future ultrathin-film solar cell designs incorporating nanostructured thin active layers. PMID:27641965

  12. In vivo photothermal optical coherence tomography for non-invasive imaging of endogenous absorption agents

    PubMed Central

    Makita, Shuichi; Yasuno, Yoshiaki

    2015-01-01

    In vivo photothermal optical coherence tomography (OCT) is demonstrated for cross-sectional imaging of endogenous absorption agents. In order to compromise the sensitivity, imaging speed, and sample motion immunity, a new photothermal detection scheme and phase processing method are developed. Phase-resolved swept-source OCT and fiber-pigtailed laser diode (providing excitation at 406 nm) are combined to construct a high-sensitivity photothermal OCT system. OCT probe and excitation beam coaxially illuminate and are focused on tissues. The photothermal excitation and detection procedure is designed to obtain high efficiency of photothermal effect measurement. The principle and method of depth-resolved cross-sectional imaging of absorption agents with photothermal OCT has been derived. The phase-resolved thermal expansion detection algorithm without motion artifact enables in vivo detection of photothermal effect. Phantom imaging with a blood phantom and in vivo human skin imaging are conducted. A phantom with guinea-pig blood as absorber has been scanned by the photothermal OCT system to prove the concept of cross-sectional absorption agent imaging. An in vivo human skin measurement is also performed with endogenous absorption agents. PMID:26137374

  13. In vivo photothermal optical coherence tomography for non-invasive imaging of endogenous absorption agents.

    PubMed

    Makita, Shuichi; Yasuno, Yoshiaki

    2015-05-01

    In vivo photothermal optical coherence tomography (OCT) is demonstrated for cross-sectional imaging of endogenous absorption agents. In order to compromise the sensitivity, imaging speed, and sample motion immunity, a new photothermal detection scheme and phase processing method are developed. Phase-resolved swept-source OCT and fiber-pigtailed laser diode (providing excitation at 406 nm) are combined to construct a high-sensitivity photothermal OCT system. OCT probe and excitation beam coaxially illuminate and are focused on tissues. The photothermal excitation and detection procedure is designed to obtain high efficiency of photothermal effect measurement. The principle and method of depth-resolved cross-sectional imaging of absorption agents with photothermal OCT has been derived. The phase-resolved thermal expansion detection algorithm without motion artifact enables in vivo detection of photothermal effect. Phantom imaging with a blood phantom and in vivo human skin imaging are conducted. A phantom with guinea-pig blood as absorber has been scanned by the photothermal OCT system to prove the concept of cross-sectional absorption agent imaging. An in vivo human skin measurement is also performed with endogenous absorption agents.

  14. Open-Ended Recursive Approach for the Calculation of Multiphoton Absorption Matrix Elements.

    PubMed

    Friese, Daniel H; Beerepoot, Maarten T P; Ringholm, Magnus; Ruud, Kenneth

    2015-03-10

    We present an implementation of single residues for response functions to arbitrary order using a recursive approach. Explicit expressions in terms of density-matrix-based response theory for the single residues of the linear, quadratic, cubic, and quartic response functions are also presented. These residues correspond to one-, two-, three- and four-photon transition matrix elements. The newly developed code is used to calculate the one-, two-, three- and four-photon absorption cross sections of para-nitroaniline and para-nitroaminostilbene, making this the first treatment of four-photon absorption in the framework of response theory. We find that the calculated multiphoton absorption cross sections are not very sensitive to the size of the basis set as long as a reasonably large basis set with diffuse functions is used. The choice of exchange-correlation functional, however, significantly affects the calculated cross sections of both charge-transfer transitions and other transitions, in particular, for the larger para-nitroaminostilbene molecule. We therefore recommend the use of a range-separated exchange-correlation functional in combination with the augmented correlation-consistent double-ζ basis set aug-cc-pVDZ for the calculation of multiphoton absorption properties.

  15. Open-Ended Recursive Approach for the Calculation of Multiphoton Absorption Matrix Elements

    PubMed Central

    2015-01-01

    We present an implementation of single residues for response functions to arbitrary order using a recursive approach. Explicit expressions in terms of density-matrix-based response theory for the single residues of the linear, quadratic, cubic, and quartic response functions are also presented. These residues correspond to one-, two-, three- and four-photon transition matrix elements. The newly developed code is used to calculate the one-, two-, three- and four-photon absorption cross sections of para-nitroaniline and para-nitroaminostilbene, making this the first treatment of four-photon absorption in the framework of response theory. We find that the calculated multiphoton absorption cross sections are not very sensitive to the size of the basis set as long as a reasonably large basis set with diffuse functions is used. The choice of exchange–correlation functional, however, significantly affects the calculated cross sections of both charge-transfer transitions and other transitions, in particular, for the larger para-nitroaminostilbene molecule. We therefore recommend the use of a range-separated exchange–correlation functional in combination with the augmented correlation-consistent double-ζ basis set aug-cc-pVDZ for the calculation of multiphoton absorption properties. PMID:25821415

  16. Organoplatinum chromophores for application in high-performance nonlinear absorption materials.

    PubMed

    Liao, Chen; Shelton, Abigail H; Kim, Kye-Young; Schanze, Kirk S

    2011-09-01

    Chromophores and materials that exhibit nonlinear absorption over a broad spectrum and with high temporal dynamic range are of interest for application in materials engineering and biology. Recent work by a number of research groups has led to the development of a new family of organometallic chromophores and materials featuring interesting and useful nonlinear absorption properties. These systems contain the platinum acetylide moiety as a fundamental molecular unit, combined with delocalized, π-conjugated electron systems. These organometallic chromophores provide a unique combination of properties, such as negligible ground state absorption in the visible region, large spin-orbit coupling giving rise to high triplet excited state yield, triplet lifetime in the microsecond domain, high two-photon cross-section in the visible and near-infrared regions, and high triplet-triplet absorption cross-section in the visible and near-infrared region. This Spotlight on Application highlights recent developments in this area, combining background and review on nonlinear absorption in platinum acetylide chromophores and describing significant recent results from our own laboratory.

  17. The UV/Vis absorption spectrum of matrix-isolated dichlorine peroxide, ClOOCl.

    PubMed

    von Hobe, Marc; Stroh, Fred; Beckers, Helmut; Benter, Thorsten; Willner, Helge

    2009-03-14

    UV/Vis absorption spectra of ClOOCl isolated in neon matrices were measured in the wavelength range 220-400 nm. The purity of the trapped samples was checked by infrared and UV/Vis matrix spectroscopy as well as low-temperature Raman spectroscopy. At wavelengths below 290 nm, the results agree with the UV spectrum recently published by Pope et al. [J. Phys. Chem. A, 2007, 111, 4322-4332]. However, the observed absorption in the long wavelength tail of the spectrum-relevant for polar stratospheric ozone loss-is substantially higher than reported by Pope et al. Our results suggest the existence of a ClOOCl electronic state manifold leading to an absorption band similar to those of the near UV spectrum of Cl(2). The differences to previous studies can be accounted for quantitatively by contributions to the reported absorption spectra caused by impurities. The observed band in the long wavelength tail is supported by several high-level ab initio calculations. However, questions arise concerning absolute values of the ClOOCl cross sections, an issue that needs to be revisited in future studies. With calculated photolysis rates based on our spectrum scaled to previous cross sections at the peak absorption, the known polar catalytic ozone-destruction cycles to a large extent account for the observed ozone depletion in the spring polar stratosphere.

  18. Determination of band oscillator strengths of atmospheric molecules from high resolution vacuum ultraviolet cross section measurements

    NASA Technical Reports Server (NTRS)

    Parkinson, W. H.

    1986-01-01

    An account is given of progress in work on (1) the determination of band oscillator strengths of the Schumann-Runge absorption bands of (16)O2 and (18)O2 from cross section measurements conducted at 79 K; (2) the determination of the absolute absorption cross section of the Schumann-Runge bands of (16)O(18)O from optical depth measurements performed on mixtures of (16)O2, (18)O2 and (16)O(18)O at 79K; and (3) the influence of Schumann-Runge linewing contributions on the determination of the Herzberg continuum absorption cross section of (16)O2 in the wavelength region 194 to 204 nm. The experimental investigations are effected at high resolution with a 6.65 m scanning spectrometer which is, by virtue of its small instrumental width (EWHM = 0.0013 nm), uniquely suitable for cross section measurements of molecular bands with discrete rotational structure. Absolute cross sections, which are independent of the instrumental function and from which band oscillator strengths are directly determined, are measured for the absorption bands that are most predissociated. Such measurements are needed for (1) accurate calculations of the stratospheric production of atomic oxygen and heavy ozone formed following the photopredissociation of (18)O(16)O by solar radiation penetrating between the absorption lines of (16)O2; (2) elucidation of the mechanism of predissociation of the upper state of the Schumann-Runge bands; and (3) determination of the true shape of the Herzberg continuum cross section.

  19. Cross resonant optical antenna.

    PubMed

    Biagioni, P; Huang, J S; Duò, L; Finazzi, M; Hecht, B

    2009-06-26

    We propose a novel cross resonant optical antenna consisting of two perpendicular nanosized gold dipole antennas with a common feed gap. We demonstrate that the cross antenna is able to convert propagating fields of any polarization state into correspondingly polarized, localized, and enhanced fields and vice versa. The cross antenna structure therefore opens the road towards the control of light-matter interactions based on polarized light as well as the analysis of polarized fields on the nanometer scale.

  20. Fluid absorption solar energy receiver

    NASA Technical Reports Server (NTRS)

    Bair, Edward J.

    1993-01-01

    A conventional solar dynamic system transmits solar energy to the flowing fluid of a thermodynamic cycle through structures which contain the gas and thermal energy storage material. Such a heat transfer mechanism dictates that the structure operate at a higher temperature than the fluid. This investigation reports on a fluid absorption receiver where only a part of the solar energy is transmitted to the structure. The other part is absorbed directly by the fluid. By proportioning these two heat transfer paths the energy to the structure can preheat the fluid, while the energy absorbed directly by the fluid raises the fluid to its final working temperature. The surface temperatures need not exceed the output temperature of the fluid. This makes the output temperature of the gas the maximum temperature in the system. The gas can have local maximum temperatures higher than the output working temperature. However local high temperatures are quickly equilibrated, and since the gas does not emit radiation, local high temperatures do not result in a radiative heat loss. Thermal radiation, thermal conductivity, and heat exchange with the gas all help equilibrate the surface temperature.

  1. The absorption of polymeric composites

    NASA Astrophysics Data System (ADS)

    Řídký, R.; Popovič, M.; Rolc, S.; Drdlová, M.; Krátký, J.

    2016-06-01

    An absorption capacity of soft, viscoelastic materials at high strain rates is important for wide range of practical applications. Nowadays there are many variants of numerical models suitable for this kind of analysis. The main difficulty is in selection of the most realistic numerical model and a correct setup of many unknown material constants. Cooperation between theoretical simulations and real testing is next crucial point in the investigation process. Standard open source material database offer material properties valid for strain rates less than 250 s-1. There are experiments suitable for analysis of material properties with strain rates close to 2000 s-1. The high strain-rate characteristics of a specific porous blast energy absorbing material measured by modified Split Hopkinson Pressure Bar apparatus is presented in this study. Testing these low impedance materials using a metallic split Hopkinson pressure bar setup results in poor signal to noise ratios due to impedance mismatching. These difficulties are overcome by using polymeric Hopkinson bars. Conventional Hopkinson bar analysis cannot be used on the polymeric bars due to the viscoelastic nature of the bar material. One of the possible solution leads to complex and frequency depended Young modulus of testing bars material. This testing technique was applied to materials composed of porous glass/ceramic filler and polymeric binder, with density of 125 - 300 kg/m3 and particle size in range of 50 µm - 2 mm. The achieved material model was verified in practical application of sandwich structure includes polymeric composites under a blast test.

  2. Spectral control of an alexandrite laser for an airborne water-vapor differential absorption lidar system

    NASA Technical Reports Server (NTRS)

    Ponsardin, Patrick; Grossmann, Benoist E.; Browell, Edward V.

    1994-01-01

    A narrow-linewidth pulsed alexandrite laser has been greatly modified for improved spectral stability in an aircraft environment, and its operation has been evaluated in the laboratory for making water-vapor differential absorption lidar measurements. An alignment technique is described to achieve the optimum free spectral range ratio for the two etalons inserted in the alexandrite laser cavity, and the sensitivity of this ratio is analyzed. This technique drastically decreases the occurrence of mode hopping, which is commonly observed in a tunable, two-intracavity-etalon laser system. High spectral purity (greater than 99.85%) at 730 nm is demonstrated by the use of a water-vapor absorption line as a notch filter. The effective cross sections of 760-nm oxygen and 730-nm water-vapor absorption lines are measured at different pressures by using this laser, which has a finite linewidth of 0.02 cm(exp -1) (FWHM). It is found that for water-vapor absorption linewidths greater than 0.04 cm(exp -1) (HWHM), or for altitudes below 10 km, the laser line can be considered monochromatic because the measured effective absorption cross section is within 1% of the calculated monochromatic cross section. An analysis of the environmental sensitivity of the two intracavity etalons is presented, and a closed-loop computer control for active stabilization of the two intracavity etalons in the alexandrite laser is described. Using a water-vapor absorption line as a wavelength reference, we measure a long-term frequency drift (approximately 1.5 h) of less than 0.7 pm in the laboratory.

  3. Do Atoms Really "Emit" Absorption Lines?

    ERIC Educational Resources Information Center

    Brecher, Kenneth

    1991-01-01

    Presents three absorption line sources that enhance student understanding of the phenomena associated with the interaction of light with matter and help dispel the misconception that atoms "emit" absorption lines. Sources include neodymium, food coloring and other common household liquids, and fluorescent materials. (MDH)

  4. Iron absorption from intrinsically-labeled lentils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Low iron (Fe) absorption from important staple foods may contribute to Fe deficiency in developing countries. To date, there are few studies examining the Fe bioavailability of pulse crops as commonly prepared and consumed by humans. The objectives of this study were to characterize the Fe absorpt...

  5. A Low-Cost Quantitative Absorption Spectrophotometer

    ERIC Educational Resources Information Center

    Albert, Daniel R.; Todt, Michael A.; Davis, H. Floyd

    2012-01-01

    In an effort to make absorption spectrophotometry available to high school chemistry and physics classes, we have designed an inexpensive visible light absorption spectrophotometer. The spectrophotometer was constructed using LEGO blocks, a light emitting diode, optical elements (including a lens), a slide-mounted diffraction grating, and a…

  6. Atmospheric Solar Heating in Minor Absorption Bands

    NASA Technical Reports Server (NTRS)

    Chou, Ming-Dah

    1998-01-01

    Solar radiation is the primary source of energy driving atmospheric and oceanic circulations. Concerned with the huge computing time required for computing radiative transfer in weather and climate models, solar heating in minor absorption bands has often been neglected. The individual contributions of these minor bands to the atmospheric heating is small, but collectively they are not negligible. The solar heating in minor bands includes the absorption due to water vapor in the photosynthetically active radiation (PAR) spectral region from 14284/cm to 25000/cm, the ozone absorption and Rayleigh scattering in the near infrared, as well as the O2 and CO2 absorption in a number of weak bands. Detailed high spectral- and angular-resolution calculations show that the total effect of these minor absorption is to enhance the atmospheric solar heating by approximately 10%. Depending upon the strength of the absorption and the overlapping among gaseous absorption, different approaches are applied to parameterize these minor absorption. The parameterizations are accurate and require little extra time for computing radiative fluxes. They have been efficiently implemented in the various atmospheric models at NASA/Goddard Space Flight Center, including cloud ensemble, mesoscale, and climate models.

  7. Low absorptance porcelain-on-aluminum coating

    NASA Technical Reports Server (NTRS)

    Leggett, H.

    1979-01-01

    Porcelain thermal-control coating for aluminum sheet and foil has solar absorptance of 0.22. Specially formulated coating absorptance is highly stable, changing only 0.03 after 1,000 hours of exposure to simulated sunlight and can be applied by standard commercial methods.

  8. Energy Absorption Behaviors of Nanoporous Systems

    DTIC Science & Technology

    2005-01-01

    energy absorption isotherms : (a) the first loading-unloading cycle; (b) the second, the third, and the fourth loading-unloading cycles without thermal...change, AV (cm- /g) Fig.7 The energy absorption isotherms under a cyclic loading in a 23. lwt% aqueous solution of NaC1. 80

  9. Absorption imaging of a single atom

    NASA Astrophysics Data System (ADS)

    Streed, Erik W.; Jechow, Andreas; Norton, Benjamin G.; Kielpinski, David

    2012-07-01

    Absorption imaging has played a key role in the advancement of science from van Leeuwenhoek's discovery of red blood cells to modern observations of dust clouds in stellar nebulas and Bose-Einstein condensates. Here we show the first absorption imaging of a single atom isolated in a vacuum. The optical properties of atoms are thoroughly understood, so a single atom is an ideal system for testing the limits of absorption imaging. A single atomic ion was confined in an RF Paul trap and the absorption imaged at near wavelength resolution with a phase Fresnel lens. The observed image contrast of 3.1 (3)% is the maximum theoretically allowed for the imaging resolution of our set-up. The absorption of photons by single atoms is of immediate interest for quantum information processing. Our results also point out new opportunities in imaging of light-sensitive samples both in the optical and X-ray regimes.

  10. Absorption imaging of a single atom.

    PubMed

    Streed, Erik W; Jechow, Andreas; Norton, Benjamin G; Kielpinski, David

    2012-07-03

    Absorption imaging has played a key role in the advancement of science from van Leeuwenhoek's discovery of red blood cells to modern observations of dust clouds in stellar nebulas and Bose-Einstein condensates. Here we show the first absorption imaging of a single atom isolated in a vacuum. The optical properties of atoms are thoroughly understood, so a single atom is an ideal system for testing the limits of absorption imaging. A single atomic ion was confined in an RF Paul trap and the absorption imaged at near wavelength resolution with a phase Fresnel lens. The observed image contrast of 3.1 (3)% is the maximum theoretically allowed for the imaging resolution of our set-up. The absorption of photons by single atoms is of immediate interest for quantum information processing. Our results also point out new opportunities in imaging of light-sensitive samples both in the optical and X-ray regimes.

  11. [Effect of altitude on iron absorption].

    PubMed

    Pizarro, F; Zavaleta, N; Hertrampf, E; Berlanga, R; Camborda, L; Olivares, M

    1998-03-01

    Iron bioavailability was evaluated in people living in high altitudes. Absorption was estimated from a reference dose of ferrous ascorbate and from a standard diet of wheat flour, using extrinsic tag radioisotope technique of 55Fe and 59Fe. Twenty four volunteers, healthy women, with ages ranging from 28 to 45 years, participated. Of those, eleven lived at 3450 meters above sea level (m.a.s.l.) in Huancayo city-Peru (study group), and 13 lived in Santiago de Chile at 630 m.a.s.l. (control group). Iron absorption from reference dose of ferrous ascorbate was 32.0% and 31.1% in the study and control groups respectively. The geometric mean of iron absorption from the standard diet, corrected to 40% of absorption of reference dose, was 9.0% and 6.9% in the study and control groups respectively (NS). The results suggest that altitude does not produce a high iron absorption in highlander residents.

  12. Novel absorption detection techniques for capillary electrophoresis

    SciTech Connect

    Xue, Yongjun

    1994-07-27

    Capillary electrophoresis (CE) has emerged as one of the most versatile separation methods. However, efficient separation is not sufficient unless coupled to adequate detection. The narrow inner diameter (I.D.) of the capillary column raises a big challenge to detection methods. For UV-vis absorption detection, the concentration sensitivity is only at the μM level. Most commercial CE instruments are equipped with incoherent UV-vis lamps. Low-brightness, instability and inefficient coupling of the light source with the capillary limit the further improvement of UV-vis absorption detection in CE. The goals of this research have been to show the utility of laser-based absorption detection. The approaches involve: on-column double-beam laser absorption detection and its application to the detection of small ions and proteins, and absorption detection with the bubble-shaped flow cell.

  13. Near-infrared absorptions of monomethylhydrazine

    NASA Technical Reports Server (NTRS)

    Murray, Mark; Kurtz, Joe

    1993-01-01

    The peak absorption coefficients for two near-infrared absorptions of monomethylhydrazine, CH3-N2H3, (MMH) were measured. Absorption bands located at 1.524 micrometers (6560/cm), 1.557 micrometers (6423/cm), and 1.583 micrometers (6316/cm) are assigned to the Delta upsilon = 2 overtones of the infared N-H stretching fundamentals at 3317, 3245 and 3177/cm. An absorption band located at 1.04 micrometers (9620 +/- 100/cm) is assigned to the Delta upsilon = 3 overtone of one of these fundamentals. The peak absorption coefficients (alpha(sub 10)) at 1.524 micrometers (6560 +/- 20/cm) and 1.04 micrometers (9620 +/- 100/cm) are 31 x 10(exp -3) and 0.97 x 10(exp -3)/(cm atm), respectively. Uncertainties in these coefficients were estimated to be less than +/- 20% due primarily to uncertainties in the partial vapor pressure of MMH.

  14. Non-degenerate two photon absorption enhancement for laser dyes by precise lock-in detection

    SciTech Connect

    Xue, B.; Katan, C.; Bjorgaard, J. A.; Kobayashi, T.

    2015-12-15

    This study demonstrates a measurement system for a non-degenerate two-photon absorption (NDTPA) spectrum. The NDTPA light sources are a white light super continuum beam (WLSC, 500 ∼ 720 nm) and a fundamental beam (798 nm) from a Ti:Sapphire laser. A reliable broadband NDTPA spectrum is acquired in a single-shot detection procedure using a 128-channel lock-in amplifier. The NDTPA spectra for several common laser dyes are measured. Two photon absorption cross section enhancements are found in the experiment and validated by theoretical calculation for all of the chromophores.

  15. Nonsequential two-photon absorption from the K shell in solid zirconium

    NASA Astrophysics Data System (ADS)

    Ghimire, Shambhu; Fuchs, Matthias; Hastings, Jerry; Herrmann, Sven C.; Inubushi, Yuichi; Pines, Jack; Shwartz, Sharon; Yabashi, Makina; Reis, David A.

    2016-10-01

    We report the observation of nonsequential two-photon absorption from the K shell of solid Zr (atomic number Z =40 ) using intense x-ray pulses from the Spring-8 Angstrom Compact Free-Electron Laser (SACLA). We determine the generalized nonlinear two-photon absorption cross section at the two-photon threshold in the range of 3.9-57 ×10-60cm4s bounded by the estimated uncertainty in the absolute intensity. The lower limit is consistent with the prediction of 3.1 ×10-60cm4s from the nonresonant Z-6 scaling for hydrogenic ions in the nonrelativistic, dipole limit.

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

    NASA Technical Reports Server (NTRS)

    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.

  17. Absorption Lineshapes in Two-Dimensional Electron Spin Resonance and the Effects of Slow Motions in Complex Fluids

    NASA Astrophysics Data System (ADS)

    Saxena, Sunil; Freed, Jack H.

    1997-02-01

    A methodology for obtaining pure absorption two-dimensional electron spin resonance spectra is presented for the case of large inhomogeneous broadening and/or slow motions. For slow motions, the spectra consist of "complex Lorentzians" superimposed with complex weighting factors, presenting a challenge to obtaining absorption spectra. It is shown how absorption-type spectra can be recovered for the two-pulse COSY and SECSY experiments in such cases. For three-pulse 2D ELDOR experiments, absorption lineshapes can be obtained for the autopeaks, whereas the cross peaks would be of mixed-mode character, in general. However, for practical cases the dispersive components in the cross peaks will be relatively small. Theoretical and experimental absorption spectra are provided to illustrate the method and to show the improved resolution obtained from absorption lineshapes. In particular, the variation in linewidths across a SECSY spectrum, which is a key component in elucidating motional dynamics, is clearly rendered in the pure absorption mode. A convenient method for introducing the necessary phase corrections for the slow-motional spectra is also provided.

  18. Chemical effect on the K shell absorption parameters of some selected cerium compounds

    NASA Astrophysics Data System (ADS)

    Akman, F.; Kaçal, M. R.; Durak, R.

    2016-08-01

    In this study, the photoelectric cross section values of Ce, CeCl3.7H2O, Ce2(SO4)3, Ce(OH)4 and Ce2O3 samples were measured in the energy range from 31.82 keV up to 51.70 keV by adopting in narrow beam geometry. Using these photoelectric cross sections, the K shell photoelectric cross sections at the K-edge, the K shell absorption jump ratios and jump factors, the Davisson-Kirchner ratios and K shell oscillator strength values were estimated experimentally. The measured parameters were compared with the theoretical calculated values. It is observed that the K shell photoelectric cross section at the K-edge and K shell oscillator strength values of an element are affected by the chemical environment of material while the K shell absorption jump ratio, K shell absorption jump factor and Davisson-Kirchner ratio are not affected by the chemical environment of material for the present samples. To the best of our knowledge, the chemical effects on the Davisson-Kirchner ratio and K shell oscillator strength have not been discussed for any element by now.

  19. Time-dependent oral absorption models

    NASA Technical Reports Server (NTRS)

    Higaki, K.; Yamashita, S.; Amidon, G. L.

    2001-01-01

    The plasma concentration-time profiles following oral administration of drugs are often irregular and cannot be interpreted easily with conventional models based on first- or zero-order absorption kinetics and lag time. Six new models were developed using a time-dependent absorption rate coefficient, ka(t), wherein the time dependency was varied to account for the dynamic processes such as changes in fluid absorption or secretion, in absorption surface area, and in motility with time, in the gastrointestinal tract. In the present study, the plasma concentration profiles of propranolol obtained in human subjects following oral dosing were analyzed using the newly derived models based on mass balance and compared with the conventional models. Nonlinear regression analysis indicated that the conventional compartment model including lag time (CLAG model) could not predict the rapid initial increase in plasma concentration after dosing and the predicted Cmax values were much lower than that observed. On the other hand, all models with the time-dependent absorption rate coefficient, ka(t), were superior to the CLAG model in predicting plasma concentration profiles. Based on Akaike's Information Criterion (AIC), the fluid absorption model without lag time (FA model) exhibited the best overall fit to the data. The two-phase model including lag time, TPLAG model was also found to be a good model judging from the values of sum of squares. This model also described the irregular profiles of plasma concentration with time and frequently predicted Cmax values satisfactorily. A comparison of the absorption rate profiles also suggested that the TPLAG model is better at prediction of irregular absorption kinetics than the FA model. In conclusion, the incorporation of a time-dependent absorption rate coefficient ka(t) allows the prediction of nonlinear absorption characteristics in a more reliable manner.

  20. Absorption-Line Studies of Seyfert Galaxies

    NASA Astrophysics Data System (ADS)

    Shull, J. Michael

    We propose to undertake a "reverberation analysis" of the variable absorption lines ill two Seyfert Galaxies (NGC 4051 and Mrk 279) to help understand the origin of intrinsic absorption lines in AGNs. Stich an analysis is a powerful tool for elucidating the radial distribution of absorbing gas in the broad-line region (BLR) and narrow-line region (NLR). Only two Seyferts have previously been studied with this technique: NGC 4151 (Bromage el al. 1985; Clavel et al. 1987) and NGC 3516 (Voit, Shull, and Begelman 1987). The absorption features have been interpreted as an outflow of ionized clouds from the nuclear region or from an accretion disk affected by UV/X-ray heating. Neither the source of the absorbing gas in these Seyferts nor the "gene" which distingishes them from other Seyferts is known. Until the 1984 onset of absorption in Mrk 279, broad self-absorbed. lines had been observed only in Seyferts of low intrinsic luminosity, such as NGC 4051. Mrk 279 is intrinsically much brighter, and therefore more quasar-like, than the other three absorptionline Seyfert I's in the CfA sample. Thus, it may show how the absorption phenomenon changes at higher luminosity and could bridge the gap between the low luminosity absorption-line Seyferts and the well-studied broad absorption-line (BAL) QSO's. In addition, Mrk 279's significant redshift will allow us to study, for the first time, the Ly-alpha line in an absorption-line Seyfert. With 3 US-1 shifts for each of these two underobserved Seyferts, we can double the number of objects in which absorption-line variability has been studied and investigate why the absorption-line strengths correlate or anti-correlate with the UV continuum.

  1. High resolution UV absorption studies of N2, SO2

    NASA Astrophysics Data System (ADS)

    Smith, Peter L.; Stark, G.; Rufus, J.; Yoshino, K.; Huber, K. P.; Ito, K.; Thorne, A. P.

    The most prominent EUV emission features in the airglows of Titan and Triton, where N2 is the major atmospheric constituent, originate from the N2c'4 1Σu+(v=0) level. We report new photoabsorption measurements of 43 rotational line oscillator strengths in the c'4(0)-X(0) band of N2. These are the first measurements of individual line f-values for this band. Such values, which are important for models of atmospheres at various temperatures, cannot be reliably calculated from band f-values and Hönl-London factors because of perturbations. A summation over the integrated cross sections of the measured lines yields a room temperature band f-value of 0.132±0.020. SO2 is an important constituent of the atmospheres of Io and Venus. Accurate photoabsorption cross section data at the temperatures of these planetary atmospheres are required for the interpretation of SO2 observations and for reliable photochemical models. Our high-resolution (λ/Δλ ≈ 450,000), room-temperature measurements of SO2 absorption cross sections in the wavelength region 198 to 220 nm [Stark et al., JGR Planets, 104, 16,585 (1999)] are being extended to lower temperatures. This work was supported in part by NASA Grant NAG5-6222 to Wellesley College.

  2. One- and two-photon absorption of highly conjugated multiporphyrin systems in the two-photon Soret transition region

    NASA Astrophysics Data System (ADS)

    Fisher, Jonathan A. N.; Susumu, Kimihiro; Therien, Michael J.; Yodh, Arjun G.

    2009-04-01

    This study presents a detailed investigation of near-infrared one- and two-photon absorption (TPA) in a series of highly conjugated (porphinato)zinc(II) compounds. The chromophores interrogated include meso-to-meso ethyne-bridged (porphinato)zinc(II) oligomers (PZnn species), (porphinato)zinc(II)-spacer-(porphinato)zinc(II) (PZn-Sp-PZn) complexes, PZnn structures featuring terminal electron-releasing and -withdrawing substituents, related conjugated arrays in which electron-rich and -poor PZn units alternate, and benchmark PZn monomers. Broadband TPA cross-section measurements were performed ratiometrically using fluorescein as a reference. Superficially, the measurements indicate very large TPA cross-sections (up to ˜104GM; 1GM =1×10-50cm4sphoton-1) in the two-photon Soret (or B-band) resonance region. However, a more careful analysis of fluorescence as a function of incident photon flux suggests that significant one-photon absorption is present in the same spectral region for all compounds in the series. TPA cross-sections are extracted for the first time for some of these compounds using a model that includes both one-photon absorption and TPA contributions. Resultant TPA cross-sections are ˜10GM. The findings suggest that large TPA cross-sections reported in the Soret resonance region of similar compounds might contain significant contributions from one-photon absorption processes.

  3. Cross-Generational Storytelling

    ERIC Educational Resources Information Center

    Smith, Cindy; Thurston, Judy Kay

    2007-01-01

    What happens when you combine senior citizens, pre-service art teachers, and elementary students? Cross-generational connections based on sharing memories, ideas, skills, laughter, tears, and creativity. The authors describe the cross-generational book exchange project. This project was initiated when a group of Central Michigan University (CMU)…

  4. Jet inclusive cross sections

    SciTech Connect

    Del Duca, V.

    1992-11-01

    Minijet production in jet inclusive cross sections at hadron colliders, with large rapidity intervals between the tagged jets, is evaluated by using the BFKL pomeron. We describe the jet inclusive cross section for an arbitrary number of tagged jets, and show that it behaves like a system of coupled pomerons.

  5. Photodissociation cross section of ClOOCl at 330 nm.

    PubMed

    Jin, Bing; Chen, I-Cheng; Huang, Wen-Tsung; Lien, Chien-Yu; Guchhait, Nikhil; Lin, Jim J

    2010-04-15

    The photolysis rate of ClOOCl is crucial in the catalytic destruction of polar stratospheric ozone. In this work, we determined the photodissociation cross section of ClOOCl at 330 nm with a molecular beam and with mass-resolved detection. The photodissociation cross section is the product of the absorption cross section and the dissociation quantum yield. We formed an effusive molecular beam of ClOOCl at a nozzle temperature of 200 or 250 K and determined its photodissociation probability by measuring the decrease of the ClOOCl intensity upon laser irradiation. By comparing with a reference molecule (Cl(2)), of which the absorption cross section and dissociation quantum yield are well-known, we determined the absolute photodissociation cross section of ClOOCl at 330 nm to be (2.31 +/- 0.11) x 10(-19) cm(2) at 200 K and (2.47 +/- 0.12) x 10(-19) cm(2) at 250 K. Impurity interference has been a well-recognized problem in conventional spectroscopic studies of ClOOCl; our mass-resolved measurement directly overcomes such a problem. This measurement of the ClOOCl photolysis cross section at 330 nm is particularly useful in constraining its atmospheric photolysis rate, which in the polar stratosphere peaks near this wavelength.

  6. Cross-Shelf Exchange.

    PubMed

    Brink, K H

    2016-01-01

    Cross-shelf exchange dominates the pathways and rates by which nutrients, biota, and materials on the continental shelf are delivered and removed. This follows because cross-shelf gradients of most properties are usually far greater than those in the alongshore direction. The resulting transports are limited by Earth's rotation, which inhibits flow from crossing isobaths. Thus, cross-shelf flows are generally weak compared with alongshore flows, and this leads to interesting observational issues. Cross-shelf flows are enabled by turbulent mixing processes, nonlinear processes (such as momentum advection), and time dependence. Thus, there is a wide range of possible effects that can allow these critical transports, and different natural settings are often governed by different combinations of processes. This review discusses examples of representative transport mechanisms and explores possible observational and theoretical paths to future progress.

  7. Effect of Water Vapor Absorption on Measurements of Atmospheric Nitrate Radical by LP-DOAS

    NASA Astrophysics Data System (ADS)

    Li, Su-wen; Liu, Wen-qing; Xie, Pin-hua; Yang, Yi-jun; Chen, De-bao; Li, Zheng

    2008-10-01

    During the measurement of atmospheric nitrate radical by long-path differential optical absorption spec-troscopy, water vapor strong absorption could affect the measurement of nitrate radical and detection limits of system. Under the tropospheric condition, the optical density of water vapor absorption is non-linearly dependent on column density. An effective method was developed to eliminate the effect of water vapor absorption. Reference spectra of water vapor based on the daytime atmospheric absorption spectra, when fitted together with change of cross section with water vapor column densities, gave a more accurate fitting of water vapor absorptions, thus its effect on the measurements of nitrate radical could be restricted to a minimum and detection limits of system reached 3.6 ppt. The modified method was applied during an intensive field campaign in the Pearl River Delta, China. The NO3 concentration in polluted air masses varied from 3.6 ppt to 82.5 ppt with an average level of 23.6±1.8 ppt.

  8. Lactose enhances mineral absorption in infancy.

    PubMed

    Ziegler, E E; Fomon, S J

    1983-05-01

    To determine if lactose promotes the intestinal absorption of calcium and other minerals by infants, metabolic balance studies were performed with infants fed two formulas nearly identical in composition except for carbohydrate. One contained only lactose and the other contained sucrose and corn starch hydrolysate. Each of six normal infants had two balance studies performed with each formula in alternating sequence. When lactose was the carbohydrate, net absorption and net retention of calcium were significantly greater than when lactose was not present in the formula. Absorptions of magnesium and manganese were also significantly enhanced by lactose. Absorptions of copper and zinc were somewhat greater (not statistically significant) when lactose was present, whereas absorption of iron was not affected. Absorption of phosphorus was not different, but urinary excretion was less when the lactose containing formula was fed and, hence, net retention of phosphorus was significantly enhanced. These results confirm findings from animal studies and previous human studies and show that, in infants, lactose has a significant and sustained promoting effect on absorption of calcium and other minerals.

  9. Reduction of patterning effects in SOA-based wavelength converters by combining cross-gain and cross-absorption modulation.

    PubMed

    Zhou, Enbo; Ohman, Filip; Cheng, Cheng; Zhang, Xinliang; Hong, Wei; Mørk, Jesper; Huang, Dexiu

    2008-12-22

    A scheme for mitigating patterning effects in wavelength conversion by using a concatenated semiconductor optical amplifier (SOA) and electroabsorption modulator (EAM) is proposed. The optimization of the parameters of the semiconductor devices and receiver electronics is theoretically investigated. The bit error ratio (BER) of the output signals in both the co-propagating and the counter-propagating configurations is quantitatively evaluated. The simulation results indicate that the patterning effect in wavelength conversion due to the slow recovery of the carrier density in the SOA can be well compensated by a concatenated EAM. The simulation results are confirmed by preliminary pump-probe experiment using a 10Gb/s clock pulse train.

  10. The effect of tea on iron absorption.

    PubMed Central

    Disler, P B; Lynch, S R; Charlton, R W; Torrance, J D; Bothwell, T H; Walker, R B; Mayet, F

    1975-01-01

    The effect of tea on iron absorption was studied in human volunteers. Absorption from solutions of FeCl3 and FeSO4, bread, a meal of rice with potato and onion soup, and uncooked haemoglobin was inhibited whether ascorbic acid was present or not. No inhibition was noted if the haemoglobin was cooked. The effect on the absorption of non-haem iron was ascribed to the formation of insoluble iron tannate complexes. Drinking tannin-containing beverages such as tea with meals may contribute to the pathogenesis of iron deficiency if the diet consists largely of vegetable foodstuffs. PMID:1168162

  11. Selective coherent perfect absorption in metamaterials

    SciTech Connect

    Nie, Guangyu; Shi, Quanchao; Zhu, Zheng; Shi, Jinhui

    2014-11-17

    We show multi-band coherent perfect absorption (CPA) in simple bilayered asymmetrically split ring metamaterials. The selectivity of absorption can be accomplished by separately excited electric and magnetic modes in a standing wave formed by two coherent counterpropagating beams. In particular, each CPA can be completely switched on/off by the phase of a second coherent wave. We propose a practical scheme for realizing multi-band coherent perfect absorption of 100% that is allowed to work from microwave to optical frequency.

  12. Not-so-resonant, resonant absorption

    NASA Astrophysics Data System (ADS)

    Brunel, F.

    1987-07-01

    When an intense electromagnetic wave is incident obliquely on a sharply bounded overdense plasma, strong energy absorption can be accounted for by the electrons that are dragged into the vacuum and sent back into the plasma with velocities v~=vosc. This mechanism is more efficient than usual resonant absorption for vosc/ω>L, with L being the density gradient length. In the very high-intensity CO2-laser-target interaction, this mechanism may account for most of the energy absorption.

  13. Total absorption by degenerate critical coupling

    SciTech Connect

    Piper, Jessica R. Liu, Victor; Fan, Shanhui

    2014-06-23

    We consider a mirror-symmetric resonator with two ports. We show that, when excited from a single port, complete absorption can be achieved through critical coupling to degenerate resonances with opposite symmetry. Moreover, any time two resonances with opposite symmetry are degenerate in frequency and absorption is always significantly enhanced. In contrast, when two resonances with the same symmetry are nearly degenerate, there is no absorption enhancement. We numerically demonstrate these effects using a graphene monolayer on top of a photonic crystal slab, illuminated from a single side in the near-infrared.

  14. The gastrointestinal absorption of the actinide elements.

    PubMed

    Harrison, J D

    1991-03-01

    The greatest uncertainty in dose estimates for the ingestion of long-lived, alpha-emitting isotopes of the actinide elements is in the values used for their fractional absorption from the gastrointestinal tract (f1 values). Recent years have seen a large increase in the available data on actinide absorption. Human data are reviewed here, together with animal data, to illustrate the effect on absorption of chemical form, incorporation into food materials, fasting and other dietary factors, and age at ingestion. The f1 values recommended by the International Commission on Radiological Protection, by an Expert Group of the Nuclear Energy Agency and by the National Radiological Protection Board are discussed.

  15. Absorption of surface acoustic waves by graphene

    NASA Astrophysics Data System (ADS)

    Zhang, S. H.; Xu, W.

    2011-06-01

    We present a theoretical study on interactions of electrons in graphene with surface acoustic waves (SAWs). We find that owing to momentum and energy conservation laws, the electronic transition accompanied by the SAW absorption cannot be achieved via inter-band transition channels in graphene. For graphene, strong absorption of SAWs can be observed in a wide frequency range up to terahertz at room temperature. The intensity of SAW absorption by graphene depends strongly on temperature and can be adjusted by changing the carrier density. This study is relevant to the exploration of the acoustic properties of graphene and to the application of graphene as frequency-tunable SAW devices.

  16. A study of sound absorption by street canyon boundaries and asphalt rubber concrete pavement

    NASA Astrophysics Data System (ADS)

    Drysdale, Graeme Robert

    A sound field model, based on a classical diffusion equation, is extended to account for sound absorption in a diffusion parameter used to model sound energy in a narrow street canyon. The model accounts for a single sound absorption coefficient, separate accommodation coefficients and a combination of separate absorption and accommodation coefficients from parallel canyon walls. The new expressions are compared to the original formula through numerical simulations to reveal the effect of absorption on sound diffusion. The newly established analytical formulae demonstrate satisfactory agreement with their predecessor under perfect reflection. As well, the influence of the extended diffusion parameter on normalized sound pressure levels in a narrow street canyon is in agreement with experimental data. The diffusion parameters are used to model sound energy density in a street canyon as a function of the sound absorption coefficient of the street canyon walls. The acoustic and material properties of conventional and asphalt rubber concrete (ARC) pavement are also studied to assess how the crumb rubber content influences sound absorption in street canyons. The porosity and absolute permeability of compacted specimens of asphalt rubber concrete are measured and compared to their normal and random incidence sound absorption coefficients as a function of crumb rubber content in the modified binder. Nonlinear trends are found between the sound absorption coefficients, porosity and absolute permeability of the compacted specimens and the percentage of crumb rubber in the modified binders. The cross-sectional areas of the air voids on the surfaces of the compacted specimens are measured using digital image processing techniques and a linear relationship is obtained between the average void area and crumb rubber content. The measured material properties are used to construct an empirical formula relating the average porosity, normal incidence noise reduction coefficients and

  17. CO2 Capture by Absorption with Potassium Carbonate

    SciTech Connect

    Gary T. Rochelle; Eric Chen; Babatunde Oyenekan; Andrew Sexton; Amorvadee Veawab

    2006-04-28

    The objective of this work is to improve the process for CO{sub 2} capture by alkanolamine absorption/stripping by developing an alternative solvent, aqueous K{sub 2}CO{sub 3} promoted by piperazine. The final campaign of the pilot plant was completed in February 2006 with 5m K{sup +}/2.5m PZ and 6.4m K{sup +}/1.6m PZ using Flexipac AQ Style 20. The new cross-exchanger reduced the approach temperature to less than 9 C. Stripper modeling has demonstrated that a configuration with a ''Flashing Feed'' requires 6% less work that a simple stripper. The oxidative degradation of piperazine proceeds more slowly than that of monoethanolamine and produces ethylenediamine and other products. Uninhibited 5 m KHCO{sub 3}/2.5 m PZ corrodes 5 to 6 times faster that 30% MEA with 0.2 mol CO{sub 2}/mol MEA.

  18. Imaging Catalytic Surfaces by Multiplexed Capillary Electrophoresis With Absorption Detection

    SciTech Connect

    Christodoulou, Michael

    2002-01-01

    A new technique for in situ imaging and screening heterogeneous catalysts by using multiplexed capillary electrophoresis with absorption detection was developed. By bundling the inlets of a large number of capillaries, an imaging probe can be created that can be used to sample products formed directly from a catalytic surface with high spatial resolution. In this work, they used surfaces made of platinum, iron or gold wires as model catalytic surfaces for imaging. Various shapes were recorded including squares and triangles. Model catalytic surfaces consisting of both iron and platinum wires in the shape of a cross were also imaged successfully. Each of the two wires produced a different electrochemical product that was separated by capillary electrophoresis. Based on the collected data they were able to distinguish the products from each wire in the reconstructed image.

  19. Molar Absorptivity Measurements in Absorbing Solvents: Impact on Solvent Absorptivity Values.

    PubMed

    Bohman, Ariel; Arnold, Mark A

    2016-10-18

    Molar absorptivity is a fundamental molecular property that quantifies absorption strength as a function of wavelength. Absolute measurements of molar absorptivity demand accounting for all mechanisms of light attenuation, including reflective losses at interfaces associated with the sample. Ideally, such measurements are performed in nonabsorbing solvents and reflective losses can be determined in a straightforward manner from Fresnel equations or effectively accounted for by path length difference methods. At near-infrared wavelengths, however, many solvents, including water, are absorbing which complicates the quantification of reflective losses. Here, generalized equations are developed for calculating absolute molar absorptivities of neat liquids wherein the dependency of reflective loss on absorption properties of the liquid are considered explicitly. The resulting equations are used to characterize sensitivity of absolute molar absorptivity measurements for solvents to the absorption strength of the solvent as well as the path length of the measurement. Methods are derived from these equations to properly account for reflective losses in general and the effectiveness of these methods is demonstrated for absolute molar absorptivity measurements for water over the combination region (5000-4000 cm(-1)) of the near-infrared spectrum. Results indicate that ignoring solvent absorption effects can incorporate wide ranging systematic errors depending upon experimental conditions. As an example, systematic errors range from 0 to 10% for common conditions used in the measurement of absolute molar absorptivity of water over the combination region of the near-infrared spectrum.

  20. Electromagnetically induced absorption via incoherent collisions

    SciTech Connect

    Yang Xihua; Sheng Jiteng; Xiao Min

    2011-10-15

    We conduct theoretical studies on electromagnetically induced absorption via incoherent collisions in an inhomogeneously broadened ladder-type three-level system with the density-matrix approach. The effects of the collision-induced coherence decay rates as well as the probe laser field intensity on the probe field absorption are examined. It is shown that with the increase of the collisional decay rates in a moderate range, a narrow dip due to electromagnetically induced transparency superimposed on the Doppler-broadened absorption background can be turned into a narrow peak under the conditions that the probe field intensity is not very weak as compared to the pump field, which results from the enhancement of constructive interference and suppression of destructive interference between one-photon and multiphoton transition pathways. The physical origin of the collision-assisted electromagnetically induced absorption is analyzed with a power-series solution of the density-matrix equations.

  1. Induced Transparency and Absorption in Coupled Microresonators

    NASA Technical Reports Server (NTRS)

    Smith, David D.; Chang, Hongrok

    2004-01-01

    We review the conditions for the occurrence of coherence phenomena in passive coupled optical microresonators. We derive the effective steady-state response and determine conditions for induced transparency and absorption in these systems.

  2. Terahertz absorption spectra of highly energetic chemicals

    NASA Astrophysics Data System (ADS)

    Slingerland, E. J.; Vallon, M. K.; Jahngen, E. G. E.; Giles, R. H.; Goyette, T. M.

    2010-04-01

    Research into absorption spectra is useful for detecting chemicals in the field. Each molecule absorbs a set of specific frequencies, which are dependent on the molecule's structure. While theoretical models are available for predicting the absorption frequencies of a particular molecule, experimental measurements are a more reliable method of determining a molecule's actual absorption behavior. The goal of this research is to explore chemical markers (absorption frequencies) that can be used to identify highly energetic molecules of interest to the remote sensing community. Particular attention was paid to the frequency ranges located within the terahertz transmission windows of the atmosphere. In addition, theoretical derivations, with the purpose of calculating the detection limits of such chemicals, will also be presented.

  3. Performance Analysis of Solution Transportation Absorption Chiller

    NASA Astrophysics Data System (ADS)

    Kiani, Behdad; Hamamoto, Yoshinori; Akisawa, Atsushi; Kashiwagi, Takao

    Thermally activated advanced absorption cycles are considered promising candidates to replace CFCs, HCFCs and HFCs for residential and commercial applications. In such absorption systems, it is desirable to utilize the waste heat from industries for heating and cooling applications in commercial and residential sectors. For this purpose, it is necessary to transport energy over some distance because the waste heat source and demand are generally located apart from each other. Transportation of steam, hot water or chilled water requires high construction costs for insulation. There is an efficient method of energy transportation using absorption system called “ Solution Transportation Absorption System (STA)”. The solution is transported at an ambient temperature so that tube-insulations not required. This paper shows the simulation of the abovementioned system and the optimal result, using mathematical optimization. The optimum system with industry‧s waste heat utilization is obtained. At the end, the effect on the pollution emission and energy conservation is obtained.

  4. Absorption chillers: Part of the solution

    SciTech Connect

    Occhionero, A.J. ); Hughes, P.J. ); Reid, E.A. )

    1991-01-01

    Acid rain, ozone depletion, global warming, and implementation economics are considered as they relate to the advisability of expanding the application of absorption chillers. Introductory and background information are provided to put the discussion in the proper context. Then all four issues are discussed separately as they relate to absorption chillers. Acid rain and ozone depletion concerns, and implementation economics, are found to support the expanded use of absorption chillers. The global warming concern is found to be more of a gray area, but the areas of benefit correspond well with the conditions of greatest economic advantage. All things considered, absorption chillers are believed to be part of the environmental and economic solution. It is further believed that integrated resource planning (IRP) processes that consider electric and gas technologies on an equal footing would come to the same conclusion for many regions of the United States. 9 refs., 3 tabs.

  5. The Absorption Spectrum of Sodium Vapor

    ERIC Educational Resources Information Center

    Ashby, R. A.; Gotthard, H. W.

    1974-01-01

    Procedures and discussion of an experiment to be used in an undergraduate course in spectroscopy are presented. The experiment involves the measurement of the absorption spectrum of sodium vapor. (DT)

  6. Optical absorption coefficients of pure water

    NASA Astrophysics Data System (ADS)

    Lu, Zheng; Zhao, Xianzhen; Fry, Edward S.

    2002-10-01

    The integrating cavity absorption meter(ICAM), which is independent of scattering effect, is used to measure the absolute values of small optical absorption coefficients of liquid. A modified ICAM is being used to measure the absorption of water in the wavelength range 300 to 700 nm. The ultrapure water produced by a two-stages water purification system reaches Type I quality. This is equal to or better than ASTM,CAP and NCCLS water quality standards. To avoid the fact that dissolved oxygen absorbs ultraviolet light due to the photochemical effect, the water sample is delivered through a nitrogen sealed system which will prevent the sample from contacting with oxygen. A compassion of our absorption spectrum with other existing data is given.

  7. Theory of absorption-induced transparency

    NASA Astrophysics Data System (ADS)

    Rodrigo, Sergio G.; García-Vidal, F. J.; Martín-Moreno, L.

    2013-10-01

    Recent experiments [Hutchison, O’Carroll, Schwartz, Genet, and Ebbesen, Angew. Chem. Int. Ed.1433-785110.1002/anie.201006019 50, 2085 (2011)] have demonstrated that optical transmission through an array of subwavelength holes in a metal film can be enhanced by the intentional presence of dyes in the system. As the transmission maximum occurs spectrally close to the absorption resonances of the dyes, this phenomenon was christened “absorption induced transparency”. Here, a theoretical study on absorption induced transparency is presented. The results show that the appearance of transmission maxima requires that the absorbent fills the holes and that it occurs also for single holes. Furthermore, it is shown that the transmission process is nonresonant, being composed by a sequential passage of the electromagnetic field through the hole. Finally, the physical origin of the phenomenon is demonstrated to be nonplasmonic, which implies that absorption induced transparency should also occur at the infrared or terahertz frequency regimes.

  8. High energy X-ray phase and dark-field imaging using a random absorption mask.

    PubMed

    Wang, Hongchang; Kashyap, Yogesh; Cai, Biao; Sawhney, Kawal

    2016-07-28

    High energy X-ray imaging has unique advantage over conventional X-ray imaging, since it enables higher penetration into materials with significantly reduced radiation damage. However, the absorption contrast in high energy region is considerably low due to the reduced X-ray absorption cross section for most materials. Even though the X-ray phase and dark-field imaging techniques can provide substantially increased contrast and complementary information, fabricating dedicated optics for high energies still remain a challenge. To address this issue, we present an alternative X-ray imaging approach to produce transmission, phase and scattering signals at high X-ray energies by using a random absorption mask. Importantly, in addition to the synchrotron radiation source, this approach has been demonstrated for practical imaging application with a laboratory-based microfocus X-ray source. This new imaging method could be potentially useful for studying thick samples or heavy materials for advanced research in materials science.

  9. Femtosecond time-domain observation of atmospheric absorption in the near-infrared spectrum

    NASA Astrophysics Data System (ADS)

    Hammond, T. J.; Monchocé, Sylvain; Zhang, Chunmei; Brown, Graham G.; Corkum, P. B.; Villeneuve, D. M.

    2016-12-01

    As light propagates through a medium, absorption caused by electronic or rovibrational transitions is evident in the transmitted spectrum. The incident electromagnetic field polarizes the medium and the absorption is due to the imaginary part of the linear susceptibility. In the time domain, the field establishes a coherence in the medium that radiates out of phase with the initial field. This coherence can persist for tens of picoseconds in atmospheric molecules such as H2O . We propagate a few-cycle laser pulse centered at 1.8 μ m through the atmosphere and measure the long-lasting molecular coherence in the time domain by high-order harmonic cross correlation. The measured optical free-induction decay of the pulse is compared with a calculation based on the calculated rovibrational spectrum of H2O absorption.

  10. Optical absorption signature of a self-assembled dye monolayer on graphene

    PubMed Central

    Sghaier, Tessnim; Le Liepvre, Sylvain; Fiorini, Céline; Douillard, Ludovic

    2016-01-01

    Summary A well-organized monolayer of alkylated perylene-3,4,9,10-tetracarboxylic-3,4,9,10-diimide (PTCDI) has been formed onto CVD graphene transferred on a transparent substrate. Its structure has been probed by scanning tunnelling microscopy and its optical properties by polarized transmission spectroscopy at varying incidence. The results show that the transition dipoles of adsorbed PTCDI are all oriented parallel to the substrate. The maximum absorption is consistent with the measured surface density of molecules and their absorption cross section. The spectrum presents mainly a large red-shift of the absorption line compared with the free molecules dispersed in solution, whereas the relative strengths of the vibronic structures are preserved. These changes are attributed to non-resonant interactions with the graphene layer and the neighbouring molecules. PMID:27547603

  11. The role of tautomers in the UV absorption of urocanic acid.

    PubMed

    Barbatti, Mario

    2011-03-14

    Tautomeric effects in the UV-absorption of trans-urocanic acid in the gas phase are investigated by means of quantum chemical calculations of sixteen tautomers at different levels, followed by absorption cross section simulations. It is shown that several trans tautomers give significant contributions to the total spectrum and that cis tautomers should not contribute to the spectrum at room temperature. The spectra of tautomers protonated at the N1 site of the imidazole ring are strongly red shifted in comparison to the spectra of tautomers protonated at the N3 site. As a consequence, excitation of the first absorption band at different wavelengths produces very different tautomeric populations. This effect helps to explain specific features observed in dispersion emission spectroscopy as well as the anomalous photophysics of urocanic acid.

  12. Gas trace detection with cavity enhanced absorption spectroscopy: a review of its process in the field

    NASA Astrophysics Data System (ADS)

    Liu, Siqi; Luo, Zhifu; Tan, Zhongqi; Long, Xingwu

    2016-11-01

    Cavity-enhanced absorption spectroscopy (CEAS) is a technology in which the intracavity absorption is deduced from the intensity of light transmitted by the high finesse optical cavity. Then the samples' parameters, such as their species, concentration and absorption cross section, would be detection. It was first proposed and demonstrated by Engeln R. [1] and O'Keefe[2] in 1998. This technology has extraordinary detection sensitivity, high resolution and good practicability, so it is used in many fields , such as clinical medicine, gas detection and basic physics research. In this paper, we focus on the use of gas trace detection, including the advance of CEAS over the past twenty years, the newest research progresses, and the prediction of this technology's development direction in the future.

  13. Effect of nonlinear absorption on self focusing of short laser pulse in a plasma

    SciTech Connect

    Kumar, Ashok

    2012-06-15

    Paraxial theory of self focusing of short pulse laser in a plasma under transient and saturating effects of nonlinearity and nonlinear absorption is developed. The absorption is averaged over the cross-section of the beam and is different for different time segments of the pulse. The electron temperature includes cumulative effect of previous history of temporal profile of pulse intensity, however, the ambipolar diffusion is taken to be faster than the heating time. The relaxation effect causes self-distortion of the pulse temporal profile where as the nonlinear absorption weakens self focusing. For the pulses of duration comparable to the electron ion collision time, the front part of the pulse gets defocused where as the latter part undergoes periodic self focusing.

  14. Ultra-broadband terahertz absorption by exciting the orthogonal diffraction in dumbbell-shaped gratings.

    PubMed

    Zang, XiaoFei; Shi, Cheng; Chen, Lin; Cai, Bin; Zhu, YiMing; Zhuang, SongLin

    2015-03-10

    Metamaterials, artificial electromagnetic media consisting of periodical subwavelength metal-based micro-structures, were widely suggested for the absorption of terahertz (THz) waves. However, they have been suffered from the absorption of THz waves just in the single-frequency owing to its resonance features. Here, in this paper, we propose a simple periodical structure, composed of two 90 degree crossed dumbbell-shaped doped-silicon grating arrays, to demonstrate broadband THz wave absorption. Our theoretical and experimental results illustrate that THz waves can be efficiently absorbed more than 95% ranging from 0.92 THz to 2.4 THz. Such an ultra-wideband polarization-independent THz absorber is realized mainly based on the mechanisms of the anti-reflection effect together with the [±1, 0]-order and [0, ±1]-order grating diffractions. The application of our investigation can be extend to THz couplers, filters, imaging, and so on.

  15. High resolution mid-infrared cross-sections for peroxyacetyl nitrate (PAN) vapour

    NASA Astrophysics Data System (ADS)

    Allen, G.; Remedios, J. J.; Newnham, D. A.; Smith, K. M.; Monks, P. S.

    2004-09-01

    Absorption spectra of peroxyacetyl nitrate (PAN, CH3C(O)OONO2) vapour at room temperature (295 K) have been measured in the mid-infrared range, 550-2200 cm-1 (18.2-3.33 µm), using a Fourier transform infrared spectrometer at instrument resolutions of 0.25 and 0.03 cm-1 (unapodised). Both cross-section data and integrated absorption intensities for the five principal bands in the PAN spectra in this spectral range have been derived from fourteen separate PAN transmission spectra measurements. Band intensities and band centre absorptivities are also reported for four weaker PAN absorption bands in the mid infrared for the first time. These observations are the highest spectral resolution measurements of PAN bands recorded in the infrared to date. For three of the five strongest bands, the absolute integrated absorption intensities are in excellent agreement with previous studies. A 4.8% lower integrated intensity was found for the 1741 cm-1 νas (NO2) PAN absorption band, possibly as a result of the removal in this work of spectra affected by subtle acetone contamination, while a 10.6% higher intensity was determined for the 1163 cm-1 ν (C-O) absorption band. No direct effects of spectral resolution were observed. The improved accuracy of these absorption cross-sections will allow more accurate investigations of PAN using infrared spectroscopy, particularly for remote sensing of PAN in the atmosphere.

  16. Pion Absorption in 3, 4He and πN Resonances

    NASA Astrophysics Data System (ADS)

    Orphanos, L.; Källne, J.; Altemus, R.; Gugelot, P. C.; McCarthy, J. S.; Minehart, R. C.; Gram, P. A. M.; Höistad, B.; Morris, C. L.; Wadlinger, E. A.; Perdrisat, C.

    1981-06-01

    The cross sections of 3,4He(π-,n)2,3H have been measured at 285, 428, 525, and 575 MeV, extending the information on the energy dependence beyond the region previously known (50-300 MeV). The cross sections beyond the region of the Δ resonance are found to decrease less rapidly than that of the elementary πd-->pp process. This energy dependence suggests that pion absorption in a nucleus is associated with π+N (off-shell) scattering which includes I=12 πN resonances that are strongly suppressed in πd-->pp.

  17. Giant Two-photon Absorption in Circular Graphene Quantum Dots in Infrared Region

    PubMed Central

    Feng, Xiaobo; Li, Zhisong; Li, Xin; Liu, Yingkai

    2016-01-01

    We investigate theoretically the two-photon absorption (TPA) for circular graphene quantum dots (GQDs) with the edge of armchair and zigzag on the basis of electronic energy states obtained by solving the Dirac-Weyl equation numerically under finite difference method. The expressions for TPA cross section are derived and the transition selection rules are obtained. Results reveal that the TPA is significantly greater in GQDs than conventional semiconductor QDs in infrared spectrum (2–6 um) with a resonant TPA cross section of up to 1011 GM. The TPA peaks are tuned by the GQDs’ size, edge and electron relaxation rate. PMID:27629800

  18. Development of an alkali chloride vapour-generating apparatus for calibration of ultraviolet absorption measurements

    NASA Astrophysics Data System (ADS)

    Leffler, T.; Brackmann, C.; Berg, M.; Aldén, M.; Li, Z. S.

    2017-02-01

    A novel design of alkali chloride vapour-generating cell has been developed, which can serve as a calibration cell for quantitative ultraviolet absorption concentration measurements and meticulous spectral investigations of alkali compounds. The calibration cell was designed to provide alkali vapour of well-controlled concentrations and temperatures, and consisted of a sealed quartz cell measuring 0.4 m in length with a temperature-controlled reservoir containing solid alkali salt. The cell was placed in a furnace and the alkali vapours generated from the reservoir have direct access to the measuring chamber. Investigations of potassium chloride (KCl) were made on sublimated vapour at temperatures 650, 700, 750, 780, and 800 °C while the reservoir temperature was kept 50 °C lower to avoid condensation. The cell provides stable KCl vapour pressures, and the furnace provides a homogenous temperature profile along the cell. KCl vapour pressures are well characterised and conform the base for determination of the KCl concentration in the cell. The alkali chloride levels matched the concentration range of the absorption setup and indicated a previously employed calibration method to overestimate KCl concentrations. The KCl absorption cross sections for wavelengths λ =197.6 nm and λ =246.2 nm were calculated to be 3.4 × 10-17 and 2.9 × 10-17 cm2/molecule, respectively. The absorption cross section spectra did not show any structural differences with increasing temperature, which could indicate influence of dimers or significant changes of the population in the KCl vibrational states. The KCl absorption cross sections thus did not show any temperature dependence in the temperature region of 700-800 °C. Moreover, the applicability of the calibration cell for measurement of other alkali chlorides and hydroxides is discussed.

  19. Effects of Photon Absorption in High Energy Heavy Ion Collisions

    NASA Astrophysics Data System (ADS)

    Winchell, Joshua; Somanathan, Sidharth; Fries, Ranier

    2014-09-01

    Photons are an important probe of the hot and dense nuclear matter created in high-energy collisions of nuclei at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). Since the mean free path of photons is larger than the size of the fireball of nuclear matter, final state interactions of photons are usually neglected. In light of recent tension between theoretical calculations and data from RHIC and LHC, we study the effect of reabsorption of photons on elliptic flow v2 and on the nuclear modification factor RAA. We consider photons emitted in primary hard collisions and thermal photons from quark-gluon plasma and hot hadron gas. We use the jet-quenching code PPM to simulate the propagation of those photons in a fireball of quark-gluon plasma and hot hadron gas created by collisions of heavy nuclei. For the absorption cross-sections we consider three different approaches: (a) Compton and pair production processes calculated by us in a static approximation, (b) the photon damping rates calculated by Thoma (1995), and (c) absorption rates derived from a recent photon calculation by van Hees et al.

  20. Absorption of transdermal and oral cyclosporine in six healthy cats.

    PubMed

    Miller, Rose; Schick, Anthea E; Boothe, Dawn M; Lewis, Thomas P

    2014-01-01

    Cyclosporine is commonly used orally to treat feline dermatoses. Due to difficulties administering oral medications, veterinarians sometimes prescribe compounded transdermal cyclosporine, despite studies showing limited absorption. The study objective was to compare cyclosporine blood concentrations after oral administration to concentrations after transdermal application of cyclosporine (prepared in pluronic lecithin organogel [PLO]) in six cats using a controlled, cross-over design with a 2 wk washout period. Cats were dosed at 5.1-7.4 mg/kg of cyclosporine q 24 hr either per os for 7 days or transdermally for 21 days. Cyclosporine blood concentrations were measured q 7 days and after the washout period. A monoclonal-based immunoassay (lower limit of quantitation was 25 ng/mL) was used. Median concentrations on the seventh day were 2,208 ng/mL (range, 1,357-3,419 ng/mL) 2 hr after orally administered cyclosporine and 37 ng/mL (range, 25-290 ng/mL) 2 hr after transdermally applied cyclosporine. Median concentration on day 21 was 58 ng/mL (range, 51-878 ng/mL) 2 hr after transdermally applied cyclosporine. Concentrations were quantifiable for transdermally applied cyclosporine, but considered therapeutic in only one of six cats. Based on those results, transdermally applied cyclosporine was not recommended in cats because of inconsistent absorption.

  1. Cross-Country Skiing.

    ERIC Educational Resources Information Center

    Arnold, Guy E.

    1980-01-01

    The cross-country ski program offered at Clarkson College in New York is described, including a brief outline of the course, necessary equipment, and suggestions for developing a similar course at other campuses. (JMF)

  2. [Cross-over studies].

    PubMed

    Bonten, Tobias N; Siegerink, Bob; van der Bom, Johanna G

    2013-01-01

    Randomized, parallel group clinical trials often require large groups of patients; this is expensive and takes time. A randomized cross-over trial can be an efficient and more affordable alternative. A cross-over design can be used to study chronic disorders in which treatments have temporary effects. Participants receive all treatments in consecutive periods and outcomes are measured after every period. In general, only a quarter of the total group size is needed for cross-over studies compared with parallel group studies. Results can be affected by period-effects and carry-over-effects, which can be prevented through randomization and a wash-out period of sufficient length. The dropping-out of participants has more negative consequences for cross-over studies than for parallel group studies.

  3. Atmospheric Absorption Parameters for Laser Propagation

    DTIC Science & Technology

    2007-11-02

    high-resolution, good photometric accuracy data for numerous bands in the 3-5 Am region, using the facility at Kitt Peak National Solar Observatory. The...L49-L52 (2001). 44. A. Castrillo, G. Gagliardi, G. Casa , and L. Gianfrani, "Combined interferometric and absorption-spectroscopic technique for...from FT visible solar absorption spectra and evaluation of spectroscopic databases," JQRST 82, 133-150 (2003). 53. D. Jacquemart, R.R. Gamache, and L.S

  4. Seasonal Solar Thermal Absorption Energy Storage Development.

    PubMed

    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.

  5. The economics of solar powered absorption cooling

    NASA Technical Reports Server (NTRS)

    Bartlett, J. C.

    1978-01-01

    Analytic procedure evaluates cost of combining absorption-cycle chiller with solar-energy system in residential or commercial application. Procedure assumes that solar-energy system already exists to heat building and that cooling system must be added. Decision is whether to cool building with conventional vapor-compression-cycle chiller or to use solar-energy system to provide heat input to absorption chiller.

  6. Total cross sections for ultracold neutrons scattered from gases

    DOE PAGES

    Seestrom, Susan Joyce; Adamek, Evan R.; Barlow, Dave; ...

    2017-01-30

    Here, we have followed up on our previous measurements of upscattering of ultracold neutrons (UCNs) from a series of gases by making measurements of total cross sections on the following gases hydrogen, ethane, methane, isobutene, n-butane, ethylene, water vapor, propane, neopentane, isopropyl alcohol, and 3He. The values of these cross sections are important for estimating the loss rate of trapped neutrons due to residual gas and are relevant to neutron lifetime measurements using UCNs. The effects of the UCN velocity and path-length distributions were accounted for in the analysis using a Monte Carlo transport code. Results are compared to ourmore » previous measurements and with the known absorption cross section for 3He scaled to our UCN energy. We find that the total cross sections for the hydrocarbon gases are reasonably described by a function linear in the number of hydrogen atoms in the molecule.« less

  7. Total cross sections for ultracold neutrons scattered from gases

    NASA Astrophysics Data System (ADS)

    Seestrom, S. J.; Adamek, E. R.; Barlow, D.; Blatnik, M.; Broussard, L. J.; Callahan, N. B.; Clayton, S. M.; Cude-Woods, C.; Currie, S.; Dees, E. B.; Fox, W.; Hoffbauer, M.; Hickerson, K. P.; Holley, A. T.; Liu, C.-Y.; Makela, M.; Medina, J.; Morley, D. J.; Morris, C. L.; Pattie, R. W.; Ramsey, J.; Roberts, A.; Salvat, D. J.; Saunders, A.; Sharapov, E. I.; Sjue, S. K. L.; Slaughter, B. A.; Walstrom, P. L.; Wang, Z.; Wexler, J.; Womack, T. L.; Young, A. R.; Vanderwerp, J.; Zeck, B. A.

    2017-01-01

    We have followed up on our previous measurements of upscattering of ultracold neutrons (UCNs) from a series of gases by making measurements of total cross sections on the following gases hydrogen, ethane, methane, isobutene, n -butane, ethylene, water vapor, propane, neopentane, isopropyl alcohol, and 3He . The values of these cross sections are important for estimating the loss rate of trapped neutrons due to residual gas and are relevant to neutron lifetime measurements using UCNs. The effects of the UCN velocity and path-length distributions were accounted for in the analysis using a Monte Carlo transport code. Results are compared to our previous measurements and with the known absorption cross section for 3He scaled to our UCN energy. We find that the total cross sections for the hydrocarbon gases are reasonably described by a function linear in the number of hydrogen atoms in the molecule.

  8. Bridge Crossing Simulator

    DTIC Science & Technology

    2014-10-07

    reaction structure, and a control system, the BCS physically simulates vehicular crossing loads for the expected life span of the bridge undergoing...information provided by the customer. In general, statics will be used to determine equations for moments and deflections based on the specific bridge ...systems. Through the use of hydraulic actuators, a reaction structure, and a control system, the Bridge Crossing Simulator physically simulates vehicular

  9. Vitamin D and intestinal calcium absorption.

    PubMed

    Christakos, Sylvia; Dhawan, Puneet; Porta, Angela; Mady, Leila J; Seth, Tanya

    2011-12-05

    The principal function of vitamin D in calcium homeostasis is to increase calcium absorption from the intestine. Calcium is absorbed by both an active transcellular pathway, which is energy dependent, and by a passive paracellular pathway through tight junctions. 1,25Dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) the hormonally active form of vitamin D, through its genomic actions, is the major stimulator of active intestinal calcium absorption which involves calcium influx, translocation of calcium through the interior of the enterocyte and basolateral extrusion of calcium by the intestinal plasma membrane pump. This article reviews recent studies that have challenged the traditional model of vitamin D mediated transcellular calcium absorption and the crucial role of specific calcium transport proteins in intestinal calcium absorption. There is also increasing evidence that 1,25(OH)(2)D(3) can enhance paracellular calcium diffusion. The influence of estrogen, prolactin, glucocorticoids and aging on intestinal calcium absorption and the role of the distal intestine in vitamin D mediated intestinal calcium absorption are also discussed.

  10. A search for intervening HI absorption

    NASA Astrophysics Data System (ADS)

    Reeves, Sarah N.; Sadler, Elaine M.; Allison, James R.; Koribalski, Baerbel S.; Curran, Stephen J.

    2013-03-01

    HI absorption-line studies provide a unique probe of the gas distribution and kinematics in galaxies well beyond the local universe (z ≳ 0.3). HI absorption-line surveys with next-generation radio telescopes will provide the first large-scale studies of HI in a redshift regime which is poorly understood. However, we currently lack the understanding to infer galaxy properties from absorption-line observations alone. To address this issue, we are conducting a search for intervening HI absorption in a sample of 20 nearby galaxies. Our aim is to investigate how the detection rate varies with distance from the galaxy. We target sight-lines to bright continuum sources, which intercept known gas-rich galaxies, selected from the HIPASS Bright Galaxy Catalogue (Koribalski et al. 2004). In our pilot sample, six galaxies with impact parameters < 20 kpc, we do not detect any absorption lines - although all are detected in 21cm emission. This indicates that an absorption non-detection cannot simply be interpreted as an absence of neutral gas - see Fig. 1. Our detection rate is low compared to previous surveys e.g. Gupta et al. (2010). This is, at least partially, due to the high resolution of the observations reducing the flux of the background source, which will also be an issue in future surveys, such as ASKAP-FLASH.

  11. High temperature measurement of water vapor absorption

    NASA Technical Reports Server (NTRS)

    Keefer, Dennis; Lewis, J. W. L.; Eskridge, Richard

    1985-01-01

    An investigation was undertaken to measure the absorption coefficient, at a wavelength of 10.6 microns, for mixtures of water vapor and a diluent gas at high temperature and pressure. The experimental concept was to create the desired conditions of temperature and pressure in a laser absorption wave, similar to that which would be created in a laser propulsion system. A simplified numerical model was developed to predict the characteristics of the absorption wave and to estimate the laser intensity threshold for initiation. A non-intrusive method for temperature measurement utilizing optical laser-beam deflection (OLD) and optical spark breakdown produced by an excimer laser, was thoroughly investigated and found suitable for the non-equilibrium conditions expected in the wave. Experiments were performed to verify the temperature measurement technique, to screen possible materials for surface initiation of the laser absorption wave and to attempt to initiate an absorption wave using the 1.5 kW carbon dioxide laser. The OLD technique was proven for air and for argon, but spark breakdown could not be produced in helium. It was not possible to initiate a laser absorption wave in mixtures of water and helium or water and argon using the 1.5 kW laser, a result which was consistent with the model prediction.

  12. Investigation of locally resonant absorption and factors affecting the absorption band of a phononic glass

    NASA Astrophysics Data System (ADS)

    Chen, Meng; Jiang, Heng; Feng, Yafei; Wang, Yuren

    2014-12-01

    We experimentally and theoretically investigated the mechanisms of acoustic absorption in phononic glass to optimize its properties. First, we experimentally studied its locally resonant absorption mechanism. From these results, we attributed its strong sound attenuation to its locally resonant units and its broadband absorption to its networked structure. These experiments also indicated that the porosity and thickness of the phononic glass must be tuned to achieve the best sound absorption at given frequencies. Then, using lumped-mass methods, we studied how the absorption bandgaps of the phononic glass were affected by various factors, including the porosity and the properties of the coating materials. These calculations gave optimal ranges for selecting the porosity, modulus of the coating material, and ratio of the compliant coating to the stiff matrix to achieve absorption bandgaps in the range of 6-30 kHz. This paper provides guidelines for designing phononic glasses with proper structures and component materials to work in specific frequency ranges.

  13. The Effect of Surface Heterogeneity on Cloud Absorption Estimates

    NASA Technical Reports Server (NTRS)

    Chiu, Jui-Yuan C.; Marshak, Alexander; Wiscombe, Warren J.

    2004-01-01

    This study presents a systematic and quantitative analysis of the effect of inhomogeneous surface albedo on shortwave cloud absorption estimates. We use 3D radiative transfer modeling with gradually complex clouds over a simplified surface to calculate cloud absorption. We find that averaging surface albedo always underestimates cloud absorption, and thus accounting for surface heterogeneity always enhances cloud absorption. However, the impact on cloud absorption estimates is not enough to explain the discrepancy between measured and model calculated shortwave cloud absorptions.

  14. Airborne differential absorption lidar system for measurements of atmospheric water vapor and aerosols.

    PubMed

    Higdon, N S; Browell, E V; Ponsardin, P; Grossmann, B E; Butler, C F; Chyba, T H; Mayo, M N; Allen, R J; Heuser, A W; Grant, W B; Ismail, S; Mayor, S D; Carter, A F

    1994-09-20

    An airborne differential absorption lidar (DIAL) system has been developed at the NASA Langley Research Center for remote measurements of atmospheric water vapor (H(2)O) and aerosols. A solid-state alexandrite laser with a 1-pm linewidth and > 99.85% spectral purity was used as the on-line transmitter. Solid-state avalanche photodiode detector technology has replaced photomultiplier tubes in the receiver system, providing an average increase by a factor of 1.5-2.5 in the signal-to-noise ratio of the H(2)O measurement. By incorporating advanced diagnostic and data-acquisition instrumentation into other subsystems, we achieved additional improvements in system operational reliability and measurement accuracy. Laboratory spectroscopic measurements of H(2)O absorption-line parameters were perfo med to reduce the uncertainties in our knowledge of the absorption cross sections. Line-center H(2)O absorption cross sections were determined, with errors of 3-6%, for more than 120 lines in the 720-nm region. Flight tests of the system were conducted during 1989-1991 on the NASA Wallops Flight Facility Electra aircraft, and extensive intercomparison measurements were performed with dew-point hygrometers and H(2)O radiosondes. The H(2)O distributions measured with the DIAL system differed by ≤ 10% from the profiles determined with the in situ probes in a variety of atmospheric conditions.

  15. Airborne differential absorption lidar system for measurements of atmospheric water vapor and aerosols

    NASA Technical Reports Server (NTRS)

    Carter, Arlen F.; Allen, Robert J.; Mayo, M. Neale; Butler, Carolyn F.; Grossman, Benoist E.; Ismail, Syed; Grant, William B.; Browell, Edward V.; Higdon, Noah S.; Mayor, Shane D.; Ponsardin, Patrick; Hueser, Alene W.

    1994-01-01

    An airborne differential absorption lidar (DIAL) system has been developed at the NASA Langley Research Center for remote measurements of atmospheric water vapor (H2O) and aerosols. A solid-state alexandrite laser with a 1-pm linewidth and greater than 99.85% spectral purity was used as the on-line transmitter. Solid-state avalanche photodiode detector technology has replaced photomultiplier tubes in the receiver system, providing an average increase by a factor of 1.5-2.5 in the signal-to-noise ratio of the H2O measurement. By incorporating advanced diagnostic and data-acquisition instrumentation into other subsystems, we achieved additional improvements in system operational reliability and measurement accuracy. Laboratory spectroscopic measurements of H2O absorption-line parameters were performed to reduce the uncertainties in our knowledge of the absorption cross sections. Line-center H2O absorption cross sections were determined, with errors of 3-6%, for more than 120 lines in the 720-nm region. Flight tests of the system were conducted during 1989-1991 on the NASA Wallops Flight Facility Electra aircraft, and extensive intercomparison measurements were performed with dew-point hygrometers and H2O radiosondes. The H2O distributions measured with the DIAL system differed by less than 10% from the profiles determined with the in situ probes in a variety of atmospheric conditions.

  16. Low absorption losses of strongly coupled surface plasmons in nanoparticle assemblies.

    PubMed

    Chang, Wei-Shun; Willingham, Britain A; Slaughter, Liane S; Khanal, Bishnu P; Vigderman, Leonid; Zubarev, Eugene R; Link, Stephan

    2011-12-13

    Coupled surface plasmons in one-dimensional assemblies of metal nanoparticles have attracted significant attention because strong interparticle interactions lead to large electromagnetic field enhancements that can be exploited for localizing and amplifying electromagnetic radiation in nanoscale structures. Ohmic loss (i.e., absorption by the metal), however, limits the performance of any application due to nonradiative surface plasmon relaxation. While absorption losses have been studied theoretically, they have not been quantified experimentally for strongly coupled surface plasmons. Here, we report on the ohmic loss in one-dimensional assemblies of gold nanoparticles with small interparticle separations of only a few nanometers and hence strong plasmon coupling. Both the absorption and scattering cross-sections of coupled surface plasmons were determined and compared to electrodynamic simulations. A lower absorption and higher scattering cross-section for coupled surface plasmons compared to surface plasmons of isolated nanoparticles suggest that coupled surface plasmons suffer smaller ohmic losses and therefore act as better antennas. These experimental results provide important insight for the design of plasmonic devices.

  17. Neutron capture cross section standards for BNL 325, Fourth Edition

    SciTech Connect

    Holden, N.E.

    1981-01-01

    This report evaluates the experimental data and recommends values for the thermal neutron cross sections and resonance integrals for the neutron capture reactions: /sup 55/Mn(n,..gamma..), /sup 59/Co(n,..gamma..) and /sup 197/Au(n,..gamma..). The failure of lithium and boron as standards due to the natural variation of the absorption cross sections of these elements is discussed. The Westcott convention, which describes the neutron spectrum as a thermal Maxwellian distribution with an epithermal component, is also discussed.

  18. Two-photon absorption of ligand-protected Ag15 nanoclusters. Towards a new class of nonlinear optics nanomaterials.

    PubMed

    Sanader, Željka; Krstić, Marjan; Russier-Antoine, Isabelle; Bertorelle, Franck; Dugourd, Philippe; Brevet, Pierre-François; Antoine, Rodolphe; Bonačić-Koutecký, Vlasta

    2016-05-14

    We report theoretical and experimental results on two-photon absorption (TPA) cross section of thiolated small silver cluster Ag15L11 exhibiting extraordinary large TPA in red. Our findings provide the responsible mechanism and allow proposing new classes of nanoclusters with large TPAs which are promising for biological and medical applications.

  19. Water-related absorption in fibrous diamonds

    NASA Astrophysics Data System (ADS)

    Zedgenizov, D. A.; Shiryaev, A. A.; Kagi, H.; Navon, O.

    2003-04-01

    Cubic and coated diamonds from several localities (Brasil, Canada, Yakutia) were investigated using spectroscopic techniques. Special emphasis was put on investigation of water-related features of transmission Infra-red and Raman spectra. Presence of molecular water is inferred from broad absorption bands in IR at 3420 and 1640 cm-1. These bands were observed in many of the investigated samples. It is likely that molecular water is present in microinclusions in liquid state, since no clear indications of solid H_2O (ice VI-VII, Kagi et al., 2000) were found. Comparison of absorption by HOH and OH vibrations shows that diamonds can be separated into two principal groups: those containing liquid water (direct proportionality of OH and HOH absorption) and those with stronger absorption by OH group. Fraction of diamonds in every group depends on their provenance. There might be positive correlation between internal pressure in microinclusions (determined using quartz barometer, Navon et al., 1988) and affiliation with diamonds containing liquid water. In many cases absorption by HOH vibration is considerably lower than absorption by hydroxyl (OH) group. This may be explained if OH groups are partially present in mineral and/or melt inclusions. This hypothesis is supported by following fact: in diamonds with strong absorption by silicates and other minerals shape and position of the OH band differs from that in diamonds with low absorption by minerals. Moreover, in Raman spectra of individual inclusions sometimes the broad band at 3100 cm-1 is observed. This band is OH-related. In some samples water distribution is not homogeneous. Central part of the diamond usually contains more water than outer parts, but this is not a general rule for all the samples. Water absorption usually correlated with absorption of other components (carbonates, silicates and others). At that fibrous diamonds with relatively high content of silicates are characterized by molecular water. OH

  20. UV absorption spectrum of the C2 Criegee intermediate CH{sub 3}CHOO

    SciTech Connect

    Smith, Mica C.; Ting, Wei-Lun; Chang, Chun-Hung; Takahashi, Kaito; Boering, Kristie A.; Lin, Jim Jr-Min

    2014-08-21

    The UV spectrum of CH{sub 3}CHOO was measured by transient absorption in a flow cell at 295 K. The absolute absorption cross sections of CH{sub 3}CHOO were measured by laser depletion in a molecular beam to be (1.06 ± 0.09) × 10{sup −17} cm{sup 2} molecule{sup −1} at 308 nm and (9.7 ± 0.6) × 10{sup −18} cm{sup 2} molecule{sup −1} at 352 nm. After scaling the UV spectrum of CH{sub 3}CHOO to the absolute cross section at 308 nm, the peak UV cross section is (1.27 ± 0.11) × 10{sup −17} cm{sup 2} molecule{sup −1} at 328 nm. Compared to the simplest Criegee intermediate CH{sub 2}OO, the UV absorption band of CH{sub 3}CHOO is similar in intensity but blue shifted by 14 nm, resulting in a 20% slower photolysis rate estimated for CH{sub 3}CHOO in the atmosphere.