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Sample records for absorption spectrum showed

  1. Absorption bands in the spectrum of Io

    NASA Technical Reports Server (NTRS)

    Cruikshank, D. P.; Jones, T. J.; Pilcher, C. B.

    1978-01-01

    Near-infrared spectra of Io in the region from 2.8 to 4.2 microns are reported which show distinct absorption features, the most notable at 4.1 microns. Frozen volatiles or atmospheric gases cannot account for these absorptions, nor do they resemble those seen in common silicate rocks. Several candidate substances, most notably nitrate and carbonate salts, show absorption features in this spectral region; the deepest band in the spectrum may be a nitrate absorption. The satellite surface is shown to be anhydrous, as indicated by the absence of the 3-micron bound water band.

  2. 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.

  3. Terahertz absorption spectrum of triacetone triperoxide (TATP)

    NASA Astrophysics Data System (ADS)

    Wilkinson, John; Konek, Christopher T.; Moran, Jesse S.; Witko, Ewelina M.; Korter, Timothy M.

    2009-08-01

    We report here, for the first time, the terahertz absorption spectrum of triacetone triperoxide (TATP). The experimental spectra are coupled with solid-state density functional theory, and preliminary assignments are provided to gain physical insight into the experimental spectrum. The calculated absorption coefficients are in excellent agreement with experiment.

  4. THE ABSORPTION SPECTRUM OF VISUAL PURPLE

    PubMed Central

    Chase, Aurin M.; Haig, Charles

    1938-01-01

    The absorption spectra of visual purple solutions extracted by various means were measured with a sensitive photoelectric spectrophotometer and compared with the classical visual purple absorption spectrum. Hardening the retinas in alum before extraction yielded visual purple solutions of much higher light transmission in the blue and violet, probably because of the removal of light-dispersing substances. Re-extraction indicated that visual purple is more soluble in the extractive than are the other colored retinal components. However, the concentration of the extractive did not affect the color purity of the extraction but did influence the keeping power. This suggests a chemical combination between the extractive and visual purple. The pH of the extractive affected the color purity of the resulting solution. Over the pH range from 5.5 to 10.0, the visual purple color purity was greatest at the low pH. Temperature during extraction was also effective, the color purity being greater the higher the temperature, up to 40°C. Drying and subsequent re-dissolving of visual purple solutions extracted with digitalin freed the solution of some protein impurities and increased its keeping power. Dialysis against distilled water seemed to precipitate visual purple from solution irreversibly. None of the treatments described improved the symmetry of the unbleached visual purple absorption spectrum sufficiently for it to resemble the classical absorption spectrum. Therefore it is very likely that the classical absorption spectrum is that of the light-sensitive group only and that the absorption spectra of our purest unbleached visual purple solutions represent the molecule as a whole. PMID:19873058

  5. Effect of shock waves on the absorption spectrum of ruby

    SciTech Connect

    Hixson, R.S.; Bellamy, P.M.; Duvall, G.E.; Wilson, C.R.

    1981-01-01

    The effect of shock loading upon the unpolarized absorption spectrum of ruby has been measured. Experiments were performed both above and below the Hugoniot elastic limit (HEL), with the experiment above the elastic limit failing due to extinction of the light upon impact. The experiments below the elastic limit were both done at about the same pressure (approx. 100 kbar), and show a shift of both absorption bands in the visible region toward shorter wavelength, the shifts agreeing well with those measured at a comparable hydrostatic pressure.

  6. The Absorption Spectrum of the η Car Ejecta

    NASA Astrophysics Data System (ADS)

    Nielsen, K. E.; Viera, G.; Gull, T. R.

    2005-09-01

    The ultraviolet spectrum of η Car and the very nearby ejecta is dominated by complex wind profiles of the extended atmosphere. Increasingly from the STIS NUV to FUV, absorption features from the ejecta and the interstellar medium are superimposed. The absorption from the foreground ejecta display a velocity dispersion between -650 > v > -100 km s-1, with two easily separated components at -146 and -513 km s-1. These two velocities components have earlier been determined to be formed at very different distances from the central source (Gull et al. 2004), and seem to be linked to Little Homunculus and the Homunculus, respectively.The -146 and -513 km s-1 components show different ionization structures. While the -146 km s-1 component shows a spectrum from almost exclusively singly ionized iron group elements, the fast -513 km s-1 has a lower excitation temperature and consequently shows lines from both neutral and singly ionized species. H2 has a huge impact on the spectrum between 1200 to 1650 Å{} and can for some regions completely describe the ejecta spectrum. The ejecta vary in absorption throughout the spectroscopic period. The -146 km s-1 component strengthens when the minimum approaches. The fast component is not significantly affected across the minimum, however, the molecular lines show a dramatic decrease in intensity likely caused by the drop of FUV radiation reaching the -513 km s-1 ejecta. In this spectral range interstellar features such as S II, C II, C IV, Si II and Si IV have a significant impact on the spectrum. We used an earlier study by Walborn et al. (2002) to estimate the ISM's influence on the η Car spectrum. Many of the interstellar lines show a large velocity dispersion (-388 to +127 km s-1). Within 0.1 arcsec of the central source, STIS resolves spatial features at the 0.25 arcsec scale. A number of strong emission lines are observable in the spectrum and associable with the Weigelt blobs B and C. During the minimum when the FUV and X

  7. 25. View down launch tube, showing shock absorption system. Lyon ...

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

    25. View down launch tube, showing shock absorption system. Lyon - Whiteman Air Force Base, Minuteman Missile Launch Facility Trainer T-12, Northeast of Oscar-01 Missile Alert Facility, Knob Noster, Johnson County, MO

  8. [Analysis of UV-visible absorption spectrum on the decolorization of industrial wastewater by disinfection].

    PubMed

    Huang, Xin; Wang, Long-Yong; Gao, Nai-Yun; Li, Wei-Guo

    2012-10-01

    The UV-Visible absorption spectrum of industrial wastewater was explored to introduce a substituting method determining the color of water, and to compare the decolorization efficacy of different disinfectants. The results show that the visible absorption spectrum(350-600 nm), instead of ultraviolet absorption spectrum, should be applied to characterize the color of wastewater. There is a good correlation between the features of visible absorption spectrum and the true color of wastewater. Both ozone and chlorine dioxide has a better decolorization performance than chlorine. However, the color of chlorine dioxide itself has a negative effect on decolorization. The changes in the features of visible absorption spectrum effectively reflect the variations in the color of wastewater after disinfection.

  9. The Absorption Spectrum of Iodine Vapour

    ERIC Educational Resources Information Center

    Tetlow, K. S.

    1972-01-01

    A laboratory experiment is described which presents some molecular parameters of iodine molecule by studying iodine spectrum. Points out this experiment can be conducted by sixth form students in high school laboratories. (PS)

  10. The emission/absorption FE 2 spectrum of HD 45677

    NASA Technical Reports Server (NTRS)

    Stalio, R.; Selvelli, P. L.

    1981-01-01

    The complex behavior of the emission/absorption spectrum of Fe II is analyzed. The far UV spectrum is characterized almost solely by absorption lines, while, in the near UV, strong emissions are predominant. Radiative excitation from the ground to the highest levels (chi is approximately 10 eV) with re-emission in the near UV, visible and I.R. seems to be the main mechanism capable of explaining the observed spectral features.

  11. Quantitative calculation of the absorption spectrum of the hydrogen atom

    NASA Astrophysics Data System (ADS)

    Ogilvie, J. F.; Fee, G. J.

    2014-03-01

    With mathematical software (Maple), we have calculated quantitatively the entire absorption spectrum of the hydrogen atom in its electronic ground state for transitions to both discrete and continuum states, within the purview of non-relativistic wave mechanics. We present plots of wave functions in both coordinate and momentum representations and the calculated spectra.

  12. 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.

  13. Method for improving terahertz band absorption spectrum measurement accuracy using noncontact sample thickness measurement.

    PubMed

    Li, Zhi; Zhang, Zhaohui; Zhao, Xiaoyan; Su, Haixia; Yan, Fang; Zhang, Han

    2012-07-10

    The terahertz absorption spectrum has a complex nonlinear relationship with sample thickness, which is normally measured mechanically with limited accuracy. As a result, the terahertz absorption spectrum is usually determined incorrectly. In this paper, an iterative algorithm is proposed to accurately determine sample thickness. This algorithm is independent of the initial value used and results in convergent calculations. Precision in sample thickness can be improved up to 0.1 μm. A more precise absorption spectrum can then be extracted. By comparing the proposed method with the traditional method based on mechanical thickness measurements, quantitative analysis experiments on a three-component amino acid mixture shows that the global error decreased from 0.0338 to 0.0301.

  14. Children with autism spectrum disorder show reduced adaptation to number

    PubMed Central

    Turi, Marco; Burr, David C.; Igliozzi, Roberta; Aagten-Murphy, David; Muratori, Filippo; Pellicano, Elizabeth

    2015-01-01

    Autism is known to be associated with major perceptual atypicalities. We have recently proposed a general model to account for these atypicalities in Bayesian terms, suggesting that autistic individuals underuse predictive information or priors. We tested this idea by measuring adaptation to numerosity stimuli in children diagnosed with autism spectrum disorder (ASD). After exposure to large numbers of items, stimuli with fewer items appear to be less numerous (and vice versa). We found that children with ASD adapted much less to numerosity than typically developing children, although their precision for numerosity discrimination was similar to that of the typical group. This result reinforces recent findings showing reduced adaptation to facial identity in ASD and goes on to show that reduced adaptation is not unique to faces (social stimuli with special significance in autism), but occurs more generally, for both parietal and temporal functions, probably reflecting inefficiencies in the adaptive interpretation of sensory signals. These results provide strong support for the Bayesian theories of autism. PMID:26056294

  15. Children with autism spectrum disorder show reduced adaptation to number.

    PubMed

    Turi, Marco; Burr, David C; Igliozzi, Roberta; Aagten-Murphy, David; Muratori, Filippo; Pellicano, Elizabeth

    2015-06-23

    Autism is known to be associated with major perceptual atypicalities. We have recently proposed a general model to account for these atypicalities in Bayesian terms, suggesting that autistic individuals underuse predictive information or priors. We tested this idea by measuring adaptation to numerosity stimuli in children diagnosed with autism spectrum disorder (ASD). After exposure to large numbers of items, stimuli with fewer items appear to be less numerous (and vice versa). We found that children with ASD adapted much less to numerosity than typically developing children, although their precision for numerosity discrimination was similar to that of the typical group. This result reinforces recent findings showing reduced adaptation to facial identity in ASD and goes on to show that reduced adaptation is not unique to faces (social stimuli with special significance in autism), but occurs more generally, for both parietal and temporal functions, probably reflecting inefficiencies in the adaptive interpretation of sensory signals. These results provide strong support for the Bayesian theories of autism. PMID:26056294

  16. Infrared absorption spectrum of liquid cryogen R-134a

    NASA Astrophysics Data System (ADS)

    Pikkula, Brian M.; Guiwan, Edword; Chao, Edward; Anvari, Bahman

    2004-07-01

    Cryogen spray cooling (CSC) is an effective method to minimize epidermal damage during laser treatment of various cutaneous anomalies such as port wine stains, excess hair, and facial rhytides. Radiometric temperature measurements provide a noninvasive method to estimate the skin surface temperature. Since the infrared absorption spectrum of the cryogen film has remained unknown, assumptions for those values may lead to inaccurate temperature estimations. We have constructed several high-pressure infrared transparent cuvettes to determine the absorption coefficient of room temperature R-134a in liquid phase using Fourier Transform Infrared Spectroscopy (FTIR) in the 2.5 - 14 μm spectral bandwidth. Results demonstrate that liquid R-134a has several absorption bands in the infrared, with those between 7 - 10.5 and 11.5 - 12.5 μm being the most prominent. Additionally, the absorption coefficient at two common radiometric bands, 3 - 5 and 7 - 11 μm differ by four orders of magnitude. Results of this study will lead to further improvements in interpreting radiometric temperature measurements when using CSC.

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

    PubMed

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

    2011-04-01

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

  18. 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.

  19. Spectrum sensing of trace C(2)H(2) detection in differential optical absorption spectroscopy technique.

    PubMed

    Chen, Xi; Dong, Xiaopeng

    2014-09-10

    An improved algorithm for trace C(2)H(2) detection is presented in this paper. The trace concentration is accurately calculated by focusing on the absorption spectrum from the frequency domain perspective. The advantage of the absorption spectroscopy frequency domain algorithm is its anti-interference capability. First, the influence of the background noise on the minimum detectable concentration is greatly reduced. Second, the time-consuming preprocess of spectra calibration in the differential optical absorption spectroscopy technique is skipped. Experimental results showed the detection limit of 50 ppm is achieved at a lightpath length of 0.2 m. This algorithm can be used in real-time spectrum analysis with high accuracy.

  20. The energy spectrum and the optical absorption spectrum of C{sub 60} fullerene within the Hubbard model

    SciTech Connect

    Silant’ev, A. V.

    2015-10-15

    Anticommutator Green’s functions and the energy spectrum of C{sub 60} fullerene are calculated in the approximation of static fluctuations within the Hubbard model. On the basis of this spectrum, an interpretation is proposed for the experimentally observed optical absorption bands of C{sub 60} fullerene. The parameters of C{sub 60} fullerene that characterize it within the Hubbard model are calculated by the optical absorption spectrum.

  1. Vertical transition energies vs. absorption maxima: illustration with the UV absorption spectrum of ethylene.

    PubMed

    Lasorne, Benjamin; Jornet-Somoza, Joaquim; Meyer, Hans-Dieter; Lauvergnat, David; Robb, Michael A; Gatti, Fabien

    2014-02-01

    We revisit the validity of making a direct comparison between measured absorption maxima and computed vertical transition energies within 0.1 eV to calibrate an excited-state level of theory. This is illustrated on the UV absorption spectrum of ethylene for which the usual experimental values of 7.66 eV (V←N) and 7.11 eV (R(3s)←N) cannot be compared directly to the results of electronic structure calculations for two very different reasons. After validation of our level of theory against experimental data, a new experimental reference of 7.28 eV is suggested for benchmarking the Rydberg state, and the often-cited average transition energy (7.80 eV) is confirmed as a safer estimate for the valence state.

  2. [Effects of LED spectrum combinations on the absorption of mineral elements of hydroponic lettuce].

    PubMed

    Chen, Xiao-Li; Guo, Wen-Zhong; Xue, Xu-Zhang; Mmanake Beauty, Morewane

    2014-05-01

    Lettuce (Lactuca sativa) was hydroponically cultured in a completely enclosed plant factory, in which spectrum proportion-adjustable LED panels were used as sole light source for plant growth. Absorption and content of eleven mineral elements such as K, P, Ca, Mg, Na, Fe, Mn, Zn, Cu, B and Mo in Lactuca sativa under different spectral component conditions were studied by ICP -AES technology. The results showed that: (1) Single or combined spectrums corresponding to the absorbing peaks of chlorophyll a and b (450, 660 nm) could enhance the absorbing ability of roots especially for mineral elements Na, Fe, Mn, Cu and Mo, the single red spectrum had the most significant promoting effect under which contents of those four elements were respectively 7. 8, 4. 2, 4. 0 and 3. 7 times more than that under FL; (2) Absorption of K and B was the highest under FL which was 10. 309 mg g-1 and 32. 6 microg g-1 while the values decreased significantly under single or combined spectrum of red and blue; (3) Plants grown under single blue spectrum had the lowest absorption of Ca and Mg which respectively decreased by 35% and 33% than FL; (4) Lettuce grown under the spectrum combination of 30% blue and 70% red had the highest accumulations of biomass while those grown under 20% blue and 80% red had the highest accumulations of the following seven elements Ca, Mg, Na, Fe, Mn, Zn and B. The results provided theoretical basis for adjusting nutrient solution formula and selecting light spectrum of hydroponic lettuce.

  3. [Effects of LED spectrum combinations on the absorption of mineral elements of hydroponic lettuce].

    PubMed

    Chen, Xiao-Li; Guo, Wen-Zhong; Xue, Xu-Zhang; Mmanake Beauty, Morewane

    2014-05-01

    Lettuce (Lactuca sativa) was hydroponically cultured in a completely enclosed plant factory, in which spectrum proportion-adjustable LED panels were used as sole light source for plant growth. Absorption and content of eleven mineral elements such as K, P, Ca, Mg, Na, Fe, Mn, Zn, Cu, B and Mo in Lactuca sativa under different spectral component conditions were studied by ICP -AES technology. The results showed that: (1) Single or combined spectrums corresponding to the absorbing peaks of chlorophyll a and b (450, 660 nm) could enhance the absorbing ability of roots especially for mineral elements Na, Fe, Mn, Cu and Mo, the single red spectrum had the most significant promoting effect under which contents of those four elements were respectively 7. 8, 4. 2, 4. 0 and 3. 7 times more than that under FL; (2) Absorption of K and B was the highest under FL which was 10. 309 mg g-1 and 32. 6 microg g-1 while the values decreased significantly under single or combined spectrum of red and blue; (3) Plants grown under single blue spectrum had the lowest absorption of Ca and Mg which respectively decreased by 35% and 33% than FL; (4) Lettuce grown under the spectrum combination of 30% blue and 70% red had the highest accumulations of biomass while those grown under 20% blue and 80% red had the highest accumulations of the following seven elements Ca, Mg, Na, Fe, Mn, Zn and B. The results provided theoretical basis for adjusting nutrient solution formula and selecting light spectrum of hydroponic lettuce. PMID:25095445

  4. [Decomposition of hemoglobin UV absorption spectrum into absorption spectra of prosthetic group and apoprotein by means of an additive model].

    PubMed

    Lavrinenko, I A; Vashanov, G A; Artyukhov, V G

    2015-01-01

    The decomposition pathways of hemoglobin UV absorption spectrum into the absorption spectra of the protein and non-protein components are proposed and substantiated by means of an additive model. We have established that the heme component has an absorption band with a maximum at λ(max) = 269.2 nm (ε = 97163) and the apoprotein component has an absorption band with a maximum at λ(max) = 278.4 nm (ε = 48669) for the wavelength range from 240.0 to 320.0 nm. An integral relative proportion of absorption for the heme fraction (78.8%) and apoprotein (21.2%) in the investigating wavelength range is defined.

  5. The Surprising Absence of Absorption in the Far-ultraviolet Spectrum of Mrk 231

    NASA Technical Reports Server (NTRS)

    Veilleux, S.; Trippe, M.; Hamann, F.; Rupke, D. S. N.; Tripp, T. M.; Netzer, H.; Lutz, D.; Sembach, K. R.; Krug, H.; Teng, Stacy H.; Genzel, R.; Maiolino, R.; Sturm, E.; Tacconi, L.

    2013-01-01

    Mrk 231, the nearest (z = 0.0422) quasar, hosts both a galactic-scale wind and a nuclear-scale iron low-ionization broad absorption line (FeLoBAL) outflow. We recently obtained a far-ultraviolet (FUV) spectrum of this object covering approx. 1150-1470A with the Cosmic Origins Spectrograph on board the Hubble Space Telescope. This spectrum is highly peculiar, highlighted by the presence of faint (< or approx.2% of predictions based on H(alpha)), broad (> or approx.10,000 km/s at the base), and highly blueshifted (centroid at approx. 3500 km/s) Ly(aplpha) emission. The FUV continuum emission is slightly declining at shorter wavelengths (consistent with F(sub lambda) Alpha Lambda(sup 1.7)) and does not show the presence of any obvious photospheric or wind stellar features. Surprisingly, the FUV spectrum also does not show any unambiguous broad absorption features. It thus appears to be dominated by the AGN, rather than hot stars, and virtually unfiltered by the dusty FeLoBAL screen. The observed Ly(alpha) emission is best explained if it is produced in the outflowing BAL cloud system, while the Balmer lines arise primarily from the standard broad emission line region seen through the dusty (Av approx. 7 mag) broad absorption line region. Two possible geometric models are discussed in the context of these new results.

  6. Infrared Absorption Spectrum of Matrix-Isolated Phenanthrene

    NASA Astrophysics Data System (ADS)

    Zhang, Xu; Stanley P. Sander

    2016-10-01

    The far-to-mid Infrared absorption spectrum of phenanthrene (C14H10), one of the polycyclic aromatic hydrocarbons (PAHs), has been measured in an argon matrix at 5 K. Thirty two fundamental bands for phenanthrene have been observed; one of them is detected for the first time (v54 = 1398.0 cm-1) and eight of them are detected for the first time at temperatures below room temperature (v43 = 233.8 cm-1, v42 = 425.2 cm-1, v66 = 441.6 cm-1, v65 = 499.0 cm-1, v21 = 546.3 cm-1, v63 = 714.5 cm-1, v18 = 1033.7 cm-1 and v55 = 1362.5 cm-1). The relative intensities of these 32 bands have been measured; three ( v21, v18, v54) of which are measured for the first time and six ( v43, v42, v66, v65, v63, and v55) of which are measured for the first time at temperatures below room temperature. Our low temperature study of the vibrational bands for phenanthrene provides important information for the spectral analysis of the Composite Infrared Spectrometer (CIRS) aboard the Cassini Spacecraft.

  7. Ultraviolet Absorption Spectrum of Malonaldehyde in Water Is Dominated by Solvent-Stabilized Conformations

    SciTech Connect

    Xu, Xuefei; Zheng, Jingjing; Truhlar, Donald G.

    2015-07-01

    Free energy calculations for eight enol isomers of malonaldehyde (MA) and simulation of the ultraviolet (UV) absorption spectrum in both the gas phase and water (pH = 3, where the molecule exists in neutral undeprotonated form) show that in water the two s-trans nonchelated enol conformers of MA become thermodynamically more stable than the internally hydrogen-bonded (“chelated enol”) conformer (CE). The pure CE conformer in water has a slightly red-shifted UV spectrum with respect to that in the gas phase, but the blue-shifted spectrum observed in water at pH 3 is dominated by solvent-stabilized conformations that have negligible populations in the gas phase. Density functional calculations with the solvation model based on density (SMD) and an ensemble-averaged vertical excitation model explain the experimental observations in detail.

  8. Laser excitation spectrum and the long path length absorption spectrum of formyl cyanide, CHOCN

    NASA Astrophysics Data System (ADS)

    Judge, R. H.; Moule, D. C.; Biernacki, A.; Benkel, M.; Ross, J. M.; Rustenburg, J.

    1986-04-01

    Formyl cyanide has been prepared for the first time by the flash pyrolysis of methoxyacetonitrile. The compound was found to be unstable and had a half-life of about 8 min in the vapor phase in the laser experiments. The near-UV absorption spectrum was photographed under conditions of long path length (56 m) at modest dispersion (1.5 nm/mm between 368 and 390 nm, and 0.75 nm/mm between 368 and 350 nm). Excitation spectra were recorded over the 386- to 360-nm region with a N 2 pumped dye laser. The observed spectrum proved to have an open vibrational and rotational fine structure and was assigned to the n → π ∗Ã1A″ ← X˜1A' electronic transition. Vibrational assignments were made in terms of ν' 3 (CO), ν' 4 (CHO), ν' 5 (CC), ν' 6 (CCO), ν' 7 (CCN), ν' 8 (H wag), ν' 9 (CCN), ν″ 7 (CCN), and ν″ 9 (CCN). The vibrational frequencies in both states were found to correlate closely to those of the propynal molecule.

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

    PubMed

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

    2015-12-01

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

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

    PubMed

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

    2015-12-01

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

  11. Inapplicability of small-polaron model for the explanation of infrared absorption spectrum in acetanilide.

    PubMed

    Zeković, Slobodan; Ivić, Zoran

    2009-01-01

    The applicability of small-polaron model for the interpretation of infrared absorption spectrum in acetanilide has been critically reexamined. It is shown that the energy difference between the normal and anomalous peak, calculated by means of small-polaron theory, displays pronounced temperature dependence which is in drastic contradiction with experiment. It is demonstrated that self-trapped states, which are recently suggested to explain theoretically the experimental absorption spectrum in protein, cannot cause the appearance of the peaks in absorption spectrum for acetanilide. PMID:19811399

  12. Infrared absorption spectrum of the simplest deuterated Criegee intermediate CD2OO.

    PubMed

    Huang, Yu-Hsuan; Nishimura, Yoshifumi; Witek, Henryk A; Lee, Yuan-Pern

    2016-07-28

    We report a transient infrared (IR) absorption spectrum of the simplest deuterated Criegee intermediate CD2OO recorded using a step-scan Fourier-transform spectrometer coupled with a multipass absorption cell. CD2OO was produced from photolysis of flowing mixtures of CD2I2, N2, and O2 (13 or 87 Torr) with laser light at 308 nm. The recorded spectrum shows close structural similarity with the spectrum of CH2OO reported previously [Y.-T. Su et al., Science 340, 174 (2013)]. The four bands observed at 852, 1017, 1054, and 1318 cm(-1) are assigned to the OO stretching mode, two distinct in-plane OCD bending modes, and the CO stretching mode of CD2OO, respectively, according to vibrational wavenumbers, IR intensities, rotational contours, and deuterium-isotopic shifts predicted with extensive quantum-chemical calculations. The CO-stretching mode of CD2OO at 1318 cm(-1) is blue shifted from the corresponding band of CH2OO at 1286 cm(-1); this can be explained by a mechanism based on mode mixing and isotope substitution. A band near 936 cm(-1), observed only at higher pressure (87 Torr), is tentatively assigned to the CD2 wagging mode of CD2IOO. PMID:27475359

  13. Infrared absorption spectrum of the simplest deuterated Criegee intermediate CD2OO

    NASA Astrophysics Data System (ADS)

    Huang, Yu-Hsuan; Nishimura, Yoshifumi; Witek, Henryk A.; Lee, Yuan-Pern

    2016-07-01

    We report a transient infrared (IR) absorption spectrum of the simplest deuterated Criegee intermediate CD2OO recorded using a step-scan Fourier-transform spectrometer coupled with a multipass absorption cell. CD2OO was produced from photolysis of flowing mixtures of CD2I2, N2, and O2 (13 or 87 Torr) with laser light at 308 nm. The recorded spectrum shows close structural similarity with the spectrum of CH2OO reported previously [Y.-T. Su et al., Science 340, 174 (2013)]. The four bands observed at 852, 1017, 1054, and 1318 cm-1 are assigned to the OO stretching mode, two distinct in-plane OCD bending modes, and the CO stretching mode of CD2OO, respectively, according to vibrational wavenumbers, IR intensities, rotational contours, and deuterium-isotopic shifts predicted with extensive quantum-chemical calculations. The CO-stretching mode of CD2OO at 1318 cm-1 is blue shifted from the corresponding band of CH2OO at 1286 cm-1; this can be explained by a mechanism based on mode mixing and isotope substitution. A band near 936 cm-1, observed only at higher pressure (87 Torr), is tentatively assigned to the CD2 wagging mode of CD2IOO.

  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. First principles calculation of oxygen K edge absorption spectrum of acetic acid: Relationship between the spectrum and molecular dynamics

    NASA Astrophysics Data System (ADS)

    Matsui, Yoshiki; Mizoguchi, Teruyasu

    2016-04-01

    First principles calculation of the oxygen K-edge absorption near-edge structure of liquid acetic acid was performed to investigate the relationship between the spectrum and the molecular dynamics in a liquid. The single and double bonded oxygens gave strong peaks at different energies. A liquid model constructed using a molecular dynamics simulation reproduced the experimental spectrum. We revealed that the effect of the dynamic behavior of molecules in a liquid clearly appears in the particular peak from a single-bond oxygen. The relationship between the bonding nature and the dynamic information of a molecule in a spectrum was determined and presented.

  16. High resolution absorption spectrum of dianilino in the vapor phase.

    PubMed

    Bayrakçeken, Fuat

    2009-01-01

    Photophysical and photochemical properties of diradical in the first excited state is recorded for the very first time with the IR, band structure for dianilino molecule at room temperature, in the vapor phase. In this experiment high resolution absorption spectra of anilino free radical, dianilino, aniline in the vapor phase and silicon dioxide in the solid state were recorded by flash photolysis technique photographically. Silicon dioxide absorption band between 250 and 255 nm were also observed for the reaction cell, because the cell and windows of the cell material were spectrosilica grade fused quartz. And this absorption band also used as wavelength calibration for all the photoproducts formed in the reaction cell during optical pumping.

  17. Methane absorption variations in the spectrum of Pluto

    SciTech Connect

    Buie, M.W.; Fink, U.

    1987-06-01

    The lightcurve phases of 0.18, 0.35, 0.49, and 0.98 covered by 5600-10,500 A absolute spectrophotometry of Pluto during four nights include minimum (0.98) light and one near-maximum (0.49) light. The spectra are noted to exhibit significant methane band absorption depth variations at 6200, 7200, 7900, 8400, 8600, 8900, and 10,000 A, with the minimum absorption occurring at minimum light and thereby indicating a 30-percent change in the methane column abundance in the course of three days. An attempt is made to model this absorption strength variation with rotational phase terms of an isotropic surface distribution of methane frost and a clear layer of CH4 gas. 34 references.

  18. Efficient Algorithms for Estimating the Absorption Spectrum within Linear Response TDDFT

    SciTech Connect

    Brabec, Jiri; Lin, Lin; Shao, Meiyue; Govind, Niranjan; Yang, Chao; Saad, Yousef; Ng, Esmond

    2015-10-06

    We present two iterative algorithms for approximating the absorption spectrum of molecules within linear response of time-dependent density functional theory (TDDFT) framework. These methods do not attempt to compute eigenvalues or eigenvectors of the linear response matrix. They are designed to approximate the absorption spectrum as a function directly. They take advantage of the special structure of the linear response matrix. Neither method requires the linear response matrix to be constructed explicitly. They only require a procedure that performs the multiplication of the linear response matrix with a vector. These methods can also be easily modified to efficiently estimate the density of states (DOS) of the linear response matrix without computing the eigenvalues of this matrix. We show by computational experiments that the methods proposed in this paper can be much more efficient than methods that are based on the exact diagonalization of the linear response matrix. We show that they can also be more efficient than real-time TDDFT simulations. We compare the pros and cons of these methods in terms of their accuracy as well as their computational and storage cost.

  19. Invisible ink mark detection in the visible spectrum using absorption difference.

    PubMed

    Lee, Joong; Kong, Seong G; Kang, Tae-Yi; Kim, Byounghyun; Jeon, Oc-Yeub

    2014-03-01

    One of popular techniques in gambling fraud involves the use of invisible ink marks printed on the back surface of playing cards. Such covert patterns are transparent in the visible spectrum and therefore invisible to unaided human eyes. Invisible patterns can be made visible with ultraviolet (UV) illumination or a CCD camera installed with an infrared (IR) filter depending on the type of ink materials used. Cheating gamers often wear contact lenses or eyeglasses made of IR or UV filters to recognize the secret marks on the playing cards. This paper presents an image processing technique to reveal invisible ink patterns in the visible spectrum without the aid of special equipment such as UV lighting or IR filters. A printed invisible ink pattern leaves a thin coating on the surface with different refractive index for different wavelengths of light, which results in color dispersion or absorption difference. The proposed method finds the differences of color components caused by absorption difference to detect invisible ink patterns on the surface. Experiment results show that the proposed scheme is effective for both UV-active and IR-active invisible ink materials. PMID:24529777

  20. Absorption spectrum of the firefly luciferin anion isolated in vacuo.

    PubMed

    Støchkel, Kristian; Milne, Bruce F; Brøndsted Nielsen, Steen

    2011-03-24

    The excited-state physics of the firefly luciferin anion depends on its chemical environment, and it is therefore important to establish the intrinsic behavior of the bare ion. Here we report electronic absorption spectra of the anion isolated in vacuo obtained at an electrostatic ion storage ring and an accelerator mass spectrometer where ionic dissociation is monitored on a long time scale (from 33 μs and up to 3 ms) and on a short time scale (0-3 μs), respectively. In the ring experiment the yield of all neutrals (mainly CO(2)) as a function of wavelength was measured whereas in the single pass experiment, the abundance of daughter ions formed after loss of CO(2) was recorded to provide action spectra. We find maxima at 535 and 265 nm, and that the band shape is largely determined by the sampling time interval, which is due to the kinetics of the dissociation process. Calculations at the TD-B3LYP/TZVPP++ level predict maximum absorption at 533 and 275 nm for the carboxylate isomer in excellent agreement with the experimental findings. The phenolate isomer lies higher in energy by 0.22 eV, and also its absorption maximum is calculated to be at 463 nm, which is far away from the experimental value. Our data serve to benchmark future theoretical models for bioluminescence from fireflies.

  1. Influence of nanorod absorption spectrum width on superluminality effect for laser pulse propagation

    NASA Astrophysics Data System (ADS)

    Trofimov, Vyacheslav A.; Lysak, Tatiana M.

    2016-03-01

    We investigate the influence of the finite absorption spectrum width on the soliton formation and superluminality phenomenon at a femtosecond pulse propagation in a medium with noble nanoparticles. These effects take place if a positive phase-amplitude grating is induced by laser radiation. We take into account the two-photon absorption (TPA) of laser radiation by nanorods, and time-dependent nanorod aspect ratio changing due to their melting or reshaping because of laser energy absorption, and the nanorod absorption spectrum width. On the basis of computer simulation we demonstrate these effects in a medium with positive phase-amplitude grating, induced by laser radiation, if a weak laser energy absorption takes place on the laser pulse dispersion length.

  2. Adolescents with Autism Spectrum Disorder Show a Circumspect Reasoning Bias Rather than "Jumping-to-Conclusions"

    ERIC Educational Resources Information Center

    Brosnan, Mark; Chapman, Emma; Ashwin, Chris

    2014-01-01

    People with autism spectrum disorders (ASD) often take longer to make decisions. The Autism-Psychosis Model proposes that people with autism and psychosis show the opposite pattern of results on cognitive tasks. As those with psychosis show a jump-to-conclusions reasoning bias, those with ASD should show a circumspect reasoning bias.…

  3. Plane-wave DFT-LDA calculation of the electronic structure and absorption spectrum of copper

    NASA Astrophysics Data System (ADS)

    Marini, Andrea; Onida, Giovanni; del Sole, Rodolfo

    2001-11-01

    We present an accurate, first-principles study of the electronic structure and absorption spectrum of bulk copper within density functional theory in the local density approximation, including the study of intraband transitions. We construct norm-conserving pseudopotentials (PP's) including the 3d shell (and optionally the underlying 3s and 3p shells) in the valence and requiring a relatively small plane-wave basis (60 and 140 Ry cutoff, respectively). As a consequence, these PP's are strongly nonlocal, yielding macroscopically wrong results in the absorption spectrum when momentum matrix elements are computed naively. Our results are compared with experimental photoemission, absorption, and electron energy loss data, and suggest nontrivial self-energy effects in the quasiparticle spectrum of Cu.

  4. An absorption line in the ultraviolet spectrum of 40 Eridani B

    NASA Technical Reports Server (NTRS)

    Greenstein, J. L.

    1980-01-01

    Two excellent low-resolution spectra show an absorption line of equivalent width 3 A, near 1391 A, in the typical DA (hydrogen atmosphere) white dwarf 40 Eri B. The line is confirmed by a high-resolution spectrum and is the first seen in any DA star. Ultraviolet fluxes and the profile of Lyman-alpha confirm an effective temperature near 17,000 K. If the line is Si IV, it requires a temperature near 40,000 K. Unattractive possibilities are a hot circumstellar absorbing envelope dependent on accretion from companions, or formation at large optical depth in a transparent atmosphere with high Si/H. A suggestion that H2 should be considered leads to the possible interpretation as the (0, 5) transition of the Lyman band, formed at small optical depth. The band should be stronger in cooler DAs.

  5. Reconstruction of absolute absorption spectrum of reduced heme a in cytochrome C oxidase from bovine heart.

    PubMed

    Dyuba, A V; Vygodina, T V; Konstantinov, A A

    2013-12-01

    This paper presents a new experimental approach for determining the individual optical characteristics of reduced heme a in bovine heart cytochrome c oxidase starting from a small selective shift of the heme a absorption spectrum induced by calcium ions. The difference spectrum induced by Ca2+ corresponds actually to a first derivative (differential) of the heme a(2+) absolute absorption spectrum. Such an absolute spectrum was obtained for the mixed-valence cyanide complex of cytochrome oxidase (a(2+)a3(3+)-CN) and was subsequently used as a basis spectrum for further procession and modeling. The individual absorption spectrum of the reduced heme a in the Soret region was reconstructed as the integral of the difference spectrum induced by addition of Ca2+. The spectrum of heme a(2+) in the Soret region obtained in this way is characterized by a peak with a maximum at 447 nm and half-width of 17 nm and can be decomposed into two Gaussians with maxima at 442 and 451 nm and half-widths of ~10 nm (589 cm(-1)) corresponding to the perpendicularly oriented electronic π→π* transitions B0x and B0y in the porphyrin ring. The reconstructed spectrum in the Soret band differs significantly from the "classical" absorption spectrum of heme a(2+) originally described by Vanneste (Vanneste, W. H. (1966) Biochemistry, 65, 838-848). The differences indicate that the overall γ-band of heme a(2+) in cytochrome oxidase contains in addition to the B0x and B0y transitions extra components that are not sensitive to calcium ions, or, alternatively, that the Vanneste's spectrum of heme a(2+) contains significant contribution from heme a3(2+). The reconstructed absorption band of heme a(2+) in the α-band with maximum at 605 nm and half-width of 18 nm (850 cm(-1)) corresponds most likely to the individual Q0y transition of heme a, whereas the Q0x transition contributes only weakly to the spectrum.

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  7. The ultraviolet absorption spectrum of the quasar PKS 0405-12 and the local density of Lyman-alpha absorption systems

    NASA Technical Reports Server (NTRS)

    Bahcall, John N.; Jannuzi, Buell T.; Schneider, Donald P.; Hartig, George F.

    1993-01-01

    A sample of 32 absorption lines has been identified in the ultraviolet spectrum of the z = 0.57 quasar PKS 0405-12. Data cover the wavelength range 1190-3260 A. There are 10 extragalactic Ly-alpha absorption lines in the complete sample, all with observed equivalent widths greater than or equal to 0.40 A; three of the Ly-alpha lines have Ly-beta counterparts. The number of Ly-alpha lines observed in the spectrum of PKS 0405-12 is within 1 sigma of the number predicted on the basis of previous HST observations of 3C 273 and of H1821 + 643. Combining the HST observations of 3C 273, H1821 + 643, and PKS 0405-12, we estimate the local number density of Ly-alpha systems with rest equivalent widths larger than 0.32 A to be about 15 +/- 4 Ly-alpha lines per unit redshift. Ground-based images reveal a rich field of galaxies in the direction of PKS 0405-12, including many galaxies with the brightnesses and sizes expected if they belong to a cluster associated with the quasar. The quasar spectrum does not show any evidence for absorption at the redshift of the emission lines, indicating a covering factor of less than unity for the halos of galaxies in the cluster around PKS 0405 - 12.

  8. The absorption spectrum of titanium between 1900 A and 2315 A

    NASA Technical Reports Server (NTRS)

    Forsberg, P.; Johansson, S.; Smith, P. L.

    1986-01-01

    The absorption spectrum of Ti I has been analyzed in the region 1900-2315 A. The list contains 219 lines, of which 64 have been identified as transitions between the ground term and terms of the odd configurations (3d + 4s)3 np (n = 4, 5). Sixteen new energy levels have been found, and three odd level values have been revised. Most of the identified Ti I lines are present in the solar spectrum.

  9. Analysis of urinary stone based on a spectrum absorption FTIR-ATR

    NASA Astrophysics Data System (ADS)

    Asyana, V.; Haryanto, F.; Fitri, L. A.; Ridwan, T.; Anwary, F.; Soekersi, H.

    2016-03-01

    This research analysed the urinary stone by measuring samples using Fourier transform infrared-attenuated total reflection spectroscopy and black box analysis. The main objective of this study is to find kinds of urinary stone and determine a total spectrum, which is a simple model of the chemical and mineral composition urinary stone through black box analysis using convolution method. The measurements result showed that kinds of urinary stone were pure calcium oxalate monohydrate, ion amino acid calcium oxalate monohydrate, a mixture of calcium oxalate monohydrate with calcium phosphate, a mixture of ion amino acid calcium oxalate monohydrate and calcium phosphate,pure uric acid, ion amino acid uric acid, and a mixture of calcium oxalate monohydrate with ion amino acid uric acid. The results of analysis of black box showed characteristics as the most accurate and precise to confirm the type of urinary stones based on theregion absorption peak on a graph, the results of the convolution, and the shape of the total spectrum on each urinary stones.

  10. The role of solvent structure in the absorption spectrum of solvated electrons: Mixed quantum/classical simulations in tetrahydrofuran

    NASA Astrophysics Data System (ADS)

    Bedard-Hearn, Michael J.; Larsen, Ross E.; Schwartz, Benjamin J.

    2005-04-01

    In polar fluids such as water and methanol, the peak of the solvated electron's absorption spectrum in the red has been assigned as a sum of transitions between an s-like ground state and three nearly degenerate p-like excited states bound in a quasispherical cavity. In contrast, in weakly polar solvents such as tetrahydrofuran (THF), the solvated electron has an absorption spectrum that peaks in the mid-infrared, but no definitive assignment has been offered about the origins of the spectrum or the underlying structure. In this paper, we present the results of adiabatic mixed quantum/classical molecular dynamic simulations of the solvated electron in THF, and provide a detailed explanation of the THF-solvated electron's absorption spectrum and electronic structure. Using a classical solvent model and a fully quantum mechanical excess electron, our simulations show that although the ground and first excited states are bound in a quasispherical cavity, a multitude of other, nearby solvent cavities support numerous, nearly degenerate, bound excited states that have little Franck-Condon overlap with the ground state. We show that these solvent cavities, which are partially polarized so that they act as electron trapping sites, are an inherent property of the way THF molecules pack in the liquid. The absorption spectrum is thus assigned to a sum of bound-to-bound transitions between a localized ground state and multiple disjoint excited states scattered throughout the fluid. Furthermore, we find that the usual spherical harmonic labels (e.g., s-like, p-like) are not good descriptors of the excited-state wave functions of the solvated electron in THF. Our observation of multiple disjoint excited states is consistent with femtosecond pump-probe experiments in the literature that suggest that photoexcitation of solvated electrons in THF causes them to relocalize into solvent cavities far from where they originated.

  11. Ab initio calculation of the electronic absorption spectrum of liquid water

    NASA Astrophysics Data System (ADS)

    Martiniano, Hugo F. M. C.; Galamba, Nuno; Cabral, Benedito J. Costa

    2014-04-01

    The electronic absorption spectrum of liquid water was investigated by coupling a one-body energy decomposition scheme to configurations generated by classical and Born-Oppenheimer Molecular Dynamics (BOMD). A Frenkel exciton Hamiltonian formalism was adopted and the excitation energies in the liquid phase were calculated with the equation of motion coupled cluster with single and double excitations method. Molecular dynamics configurations were generated by different approaches. Classical MD were carried out with the TIP4P-Ew and AMOEBA force fields. The BLYP and BLYP-D3 exchange-correlation functionals were used in BOMD. Theoretical and experimental results for the electronic absorption spectrum of liquid water are in good agreement. Emphasis is placed on the relationship between the structure of liquid water predicted by the different models and the electronic absorption spectrum. The theoretical gas to liquid phase blue-shift of the peak positions of the electronic absorption spectrum is in good agreement with experiment. The overall shift is determined by a competition between the O-H stretching of the water monomer in liquid water that leads to a red-shift and polarization effects that induce a blue-shift. The results illustrate the importance of coupling many-body energy decomposition schemes to molecular dynamics configurations to carry out ab initio calculations of the electronic properties in liquid phase.

  12. Ab initio calculation of the electronic absorption spectrum of liquid water

    SciTech Connect

    Martiniano, Hugo F. M. C.; Galamba, Nuno; Cabral, Benedito J. Costa

    2014-04-28

    The electronic absorption spectrum of liquid water was investigated by coupling a one-body energy decomposition scheme to configurations generated by classical and Born-Oppenheimer Molecular Dynamics (BOMD). A Frenkel exciton Hamiltonian formalism was adopted and the excitation energies in the liquid phase were calculated with the equation of motion coupled cluster with single and double excitations method. Molecular dynamics configurations were generated by different approaches. Classical MD were carried out with the TIP4P-Ew and AMOEBA force fields. The BLYP and BLYP-D3 exchange-correlation functionals were used in BOMD. Theoretical and experimental results for the electronic absorption spectrum of liquid water are in good agreement. Emphasis is placed on the relationship between the structure of liquid water predicted by the different models and the electronic absorption spectrum. The theoretical gas to liquid phase blue-shift of the peak positions of the electronic absorption spectrum is in good agreement with experiment. The overall shift is determined by a competition between the O–H stretching of the water monomer in liquid water that leads to a red-shift and polarization effects that induce a blue-shift. The results illustrate the importance of coupling many-body energy decomposition schemes to molecular dynamics configurations to carry out ab initio calculations of the electronic properties in liquid phase.

  13. Research on filling process of fuel and oxidant during detonation based on absorption spectrum technology

    NASA Astrophysics Data System (ADS)

    Lv, Xiao-Jing; Li, Ning; Weng, Chun-Sheng

    2014-12-01

    Research on detonation process is of great significance for the control optimization of pulse detonation engine. Based on absorption spectrum technology, the filling process of fresh fuel and oxidant during detonation is researched. As one of the most important products, H2O is selected as the target of detonation diagnosis. Fiber distributed detonation test system is designed to enable the detonation diagnosis under adverse conditions in detonation process. The test system is verified to be reliable. Laser signals at different working frequency (5Hz, 10Hz and 20Hz) are detected. Change of relative laser intensity in one detonation circle is analyzed. The duration of filling process is inferred from the change of laser intensity, which is about 100~110ms. The peak of absorption spectrum is used to present the concentration of H2O during the filling process of fresh fuel and oxidant. Absorption spectrum is calculated, and the change of absorption peak is analyzed. Duration of filling process calculated with absorption peak consisted with the result inferred from the change of relative laser intensity. The pulse detonation engine worked normally and obtained the maximum thrust at 10Hz under experiment conditions. The results are verified through H2O gas concentration monitoring during detonation.

  14. [Study on removing the lamp spectrum structure in differential optical absorption spectroscopy].

    PubMed

    Qu, Xiao-ying; Li, Yu-jin

    2010-11-01

    Differential optical absorption spectroscopy (DOAS) technique has been used to measure trace gases in the atmosphere by their strongly structured absorption of radiation in the UV and visible spectral range, and nowadays this technique has been widely utilized to measure trace polluted gases in the atmosphere e.g. SO2, NO2, O3, HCHO, etc. However, there exists lamp (xenon lamp or deuteriumlamp) spectrum structure in the measured band (300-700 nm) of the absorption spectra of atmosphere, which badly impacts on precision of retrieving the concentration of trace gases in the atmosphere. People home and abroad generally employ two ways to handle this problem, one is segmenting band retrieving method, another is remedial retrieving method. In the present paper, a new retrieving method to deal with this trouble is introduced. The authors used moving-window average smoothing method to obtain the slow part of the absorption spectra of atmosphere, then achieved the lamp (xenon lamp in the paper) spectrum structure in the measured band of the absorption spectra of atmosphere. The authors analyzed and retrieved the measured spectrum of the atmosphere, and the result is better than the forenamed ways. Chi-square of residuum is 2.995 x 10(-4), and this method was proved to be able to avoid shortcoming of choosing narrowband and disadvantage of discovering the new component of atmosphere in retrieving the concentration of air pollutants and measuring the air pollutants. PMID:21284148

  15. 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.

  16. Selectivity of the optical-absorption method based on an instrumental pick out of Fourier components in the absorption spectrum

    NASA Astrophysics Data System (ADS)

    Pisarevsky, Yu. V.; Kolesnikov, S. A.; Kolesnikova, E. S.; Turutin, Yu. A.; Konopelko, L. A.; Shor, N. B.

    2016-06-01

    The introduction of interference-polarization filters (IPFs) in the structure of an optical-absorption analyzer makes it possible to pick out a harmonic (a Fourier component of the absorption spectrum) providing measurement with the highest sensitivity. The selectivity of such a method of analysis is determined by overlapping the oscillations of the measured and interfering components. By the example of measurement in benzene in the presence of an interfering component (toluene), the possibility is considered for the optimization of selectivity due to the variation of the path-difference dispersion for ordinary and extraordinary interfering rays. The metrological characteristics of the interference-polarization analyzer of C6H6 confirming the results of calculations are given.

  17. Excited state absorption spectrum of chlorophyll a obtained with white-light continuum.

    PubMed

    De Boni, L; Correa, D S; Pavinatto, F J; dos Santos, D S; Mendonça, C R

    2007-04-28

    The study of excited state properties of chlorophyll a is a subject of foremost interest, given that it plays important roles in biological process and has also been proposed for applications in photonics. This work reports on the excited state absorption spectrum of chlorophyll a solution from 460 to 700 nm, obtained through the white-light continuum Z-scan technique. Saturation of absorption was observed due to the ground state depletion, induced by the white-light continuum region that is resonant with the Q band of chlorophyll a. The authors also observed reverse saturation of absorption related to the excitation from the first excited state to a higher energy level for wavelengths below 640 nm. An energy-level diagram, based on the electronic states of chlorophyll a, was employed to interpret their results, revealing that more states than the ones related to the Q and B bands participate in the excited state absorption of this molecule.

  18. Tunable ultranarrow spectrum selective absorption in a graphene monolayer at terahertz frequency

    NASA Astrophysics Data System (ADS)

    Wu, Jun

    2016-06-01

    Complete absorption in a graphene monolayer at terahertz frequency through the critical coupling effect is investigated. It is achieved by sandwiching the graphene monolayer between a dielectric grating and a Bragg grating. The designed graphene absorber exhibits near-unity absorption at resonance but with an ultranarrow spectrum and antenna-like response, which is attributed to the combined effects of guided mode resonance with dielectric grating and the photonic band gap with Bragg grating. In addition to numerical simulation, the electric field distributions are also illustrated to provide a physical understanding of the perfect absorption effect. Furthermore, the absorption performance can be tuned by only changing the Fermi level of graphene, which is beneficial for real application. It is believed that this study may be useful for designing next-generation graphene-based optoelectronic devices.

  19. Absorption spectrum of NO in the {gamma}(O, O) band

    SciTech Connect

    Zobnin, A.V.; Korotkov, A.N.

    1995-05-01

    A promising technique for determining the concentration of nitrogen oxide in the air of an industrial zone and in process gases is the measurement of the absorption of UV radiation by this molecule in the {gamma}(O,O) band with the center of {lambda}{sub 0} = 226.5 nm. This band corresponds to the transition X{sup 2}{Pi}{yields}{Alpha}{sup 2}{Sigma} of the NO molecule and is characterized by a complex rotational structure consisting of about 400 lines. This structure cannot be resolved completely by most spectral instruments. However, if the width of the spread function of the device is perceptibly smaller than the width of the given absorption band ({approx_equal}2 nm), but larger than the characteristic space between rotational lines ({approx_equal}0.02 nm), then the recorded transmission spectra of NO are almost insensitive to a change in the form of this function. In the given case, to describe the transmission spectrum it is possible to use the absorption coefficient averaged over rotational lines. And even though the Bouger-Lambert-Beer law is not strictly applicable for this spectrum, the dependence of the transmission spectrum of NO on the optical thickness, temperature, and pressure of the broadening gas can be represented in the form of an empirical dependence that can be useful in practice, for example, when processing the absorption spectra recorded by dispersion gas analyzers. Thus, the need for complex and laborious calculations is avoided, and this simplifies considerably the instrumental implementation of this method of measuring the concentration of NO. The object of the present work is to determine the empirical dependence of the absorption spectrum of NO in the {gamma}(O, O) band on the optical thickness, temperature, and pressure of the broadening gas in the ranges most frequently encountered in operation of dispersion gas analyzers.

  20. Absorption lines in the spectrum of Q0248 + 4302 due to a foreground tidal tail

    SciTech Connect

    Sargent, W.L.W.; Steidel, C.C. California Univ., Berkeley )

    1990-08-01

    The strong absorption lines in the spectrum of the quasar Q0248 + 4302 are discussed. The absorption has been shown to be produced in a sinuous tidal tail which emanates from the nearby galaxy pair G0248 + 4302A,B. There is a velocity difference of about 260 km/s between the systemic redshift of the interacting galaxies and the redshift of the tidal tail at a galactocentric distance of about 11/h kpc. The large velocity spread observed in the tail gas is probably responsible for the unusual strength of the interstellar lines. 18 refs.

  1. 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.

  2. Absorption line profiles in a companion spectrum of a mass losing cool supergiant

    NASA Technical Reports Server (NTRS)

    Rodrigues, Liliya L.; Boehm-Vitense, Erika

    1990-01-01

    Cool star winds can best be observed in resonance absorption lines seen in the spectrum of a hot companion, due to the wind passing in front of the blue star. We calculated absorption line profiles that would be seen in the ultraviolet part of the blue companion spectrum. Line profiles are derived for different radial dependences of the cool star wind and for different orbital phases of the binary. Bowen and Wilson find theoretically that stellar pulsations drive mass loss. We therefore apply our calculations to the Cepheid binary S Muscae which has a B5V companion. We find an upper limit for the Cepheid mass loss of M less than or equal to 7 x 10(exp -10) solar mass per year provided that the stellar wind of the companion does not influence the Cepheid wind at large distances.

  3. Absorption spectrum and analysis of the ND 4 Schüler band

    NASA Astrophysics Data System (ADS)

    Alberti, F.; Huber, K. P.; Watson, J. K. G.

    1984-09-01

    A high-resolution absorption spectrum of the main Schüler band of ND 4, with heads at 6746 and 6749 Å ( ν00 = 14828 cm -1), has been obtained by the flash discharge method, using mixtures of ND 3 and D 2. The spectrum confirms and extends the recent observation of ND 4 absorption in laser frequency modulation spectroscopy by Hunziker and co-workers. The detailed rotational analysis establishes the electronic assignment as 3 p2F2 ← 3 s2A1, and results in molecular constants in moderate agreement with expectations based on ab initio calculations. The 30-μsec lifetime of the 3 s2A1 ground state of ND 4 is consistent with the 20-μsec lower limit estimated by Porter and co-workers on the basis of neutralized-ion-beam spectroscopy.

  4. Integration of Semiconducting Sulfides for Full-Spectrum Solar Energy Absorption and Efficient Charge Separation.

    PubMed

    Zhuang, Tao-Tao; Liu, Yan; Li, Yi; Zhao, Yuan; Wu, Liang; Jiang, Jun; Yu, Shu-Hong

    2016-05-23

    The full harvest of solar energy by semiconductors requires a material that simultaneously absorbs across the whole solar spectrum and collects photogenerated electrons and holes separately. The stepwise integration of three semiconducting sulfides, namely ZnS, CdS, and Cu2-x S, into a single nanocrystal, led to a unique ternary multi-node sheath ZnS-CdS-Cu2-x S heteronanorod for full-spectrum solar energy absorption. Localized surface plasmon resonance (LSPR) in the nonstoichiometric copper sulfide nanostructures enables effective NIR absorption. More significantly, the construction of pn heterojunctions between Cu2-x S and CdS leads to staggered gaps, as confirmed by first-principles simulations. This band alignment causes effective electron-hole separation in the ternary system and hence enables efficient solar energy conversion.

  5. Absorption-line profiles in a companion spectrum of a mass-losing cool supergiant

    NASA Technical Reports Server (NTRS)

    Rodrigues, Liliya L.; Boehm-Vitense, Erika

    1992-01-01

    Cool star winds can best be observed in resonance absorption lines seen in the spectrum of a hot companion, due to the wind passing in front of the blue star. We calculated absorption line profiles that would be seen in the ultraviolet part of the blue companion spectrum. Line profiles are derived for different radial dependences of the cool star wind and for different orbital phases of the binary. Bowen and Wilson find theoretically that stellar pulsations drive mass loss. We therefore apply our calculations to the Cepheid binary S Muscae which has a B5V companion. We find an upper limit for the Cepheid mass loss of M less than or equal to 7 x 10 (exp -10) solar mass per year provided that the stellar wind of the companion does not influence the Cepheid wind at large distances.

  6. On the Putative Detection ofz>0 X-ray Absorption Featuresin the Spectrum of Mrk 421

    NASA Astrophysics Data System (ADS)

    Rasmussen, Andrew; Kahn, S. M.; Paerels, F.; den Herder, J.; Kaastra, J.; de Vries, C.

    2006-09-01

    In a series of papers, Nicastro et al. have reported the detection of z>0 OVII absorption features in the spectrum of Mrk421 obtained with the Chandra Low Energy Transmission Grating Spectrometer (LETGS). We evaluate this result in the context of a high quality spectrum of the same source obtained with the Reflection Grating Spectrometer (RGS) on XMM-Newton. The data comprise over 955ks of usable exposure time and more than 26000 counts per 50 milliAngstrom at 21.6 Angstroms. We concentrate on the spectrally clean region (21.3 < lambda < 22.5 Angstroms) where sharp features due to the astrophysically abundant OVII may reveal an intervening, warm--hot intergalactic medium (WHIM). We do not confirm detection of any of the intervening systems claimed to date. Rather, we detect only three unsurprising, astrophysically expected features down to the Log(N_i) 14.6 (3 sigma) sensitivity level. Each of the two purported WHIM features is rejected with a statistical confidence that exceeds that reported for its initial detection. While we can not rule out the existence of fainter, WHIM related features in these spectra, we suggest that previous discovery claims were premature. A more recent paper by Williams et al. claims to have demonstrated that the RGS data we analyze here do not have the resolution or statistical quality required to confirm or deny the LETGS detections. We show that our careful analysis resolves the issues encountered by Williams et al. and recovers the full resolution and statistical quality of the RGS data. We highlight the differences between our analysis and those published by Williams et al. as this may explain our disparate conclusions.

  7. Retrieval of absorptive gas columnar amounts using atmospheric hyper-spectral irradiance measurements within visible spectrum

    NASA Astrophysics Data System (ADS)

    Xu, Hua; Li, Zhengqiang; Li, Donghui; Xie, Yisong; Li, Kaitao; Qie, Lili; Zhang, Ying; Chen, Xingfeng; Zheng, Xiaobin; Li, Xin; Zhang, Yanna

    2015-10-01

    A hyper spectral ground-based instrument named Atmosphere-Surface Radiation Automatic Instrument (ASRAI) has been developed for the purpose of in-situ calibration of satellites. The apparatus has both upward and downward looking views, and thus can observe both the atmosphere and land surface. The solar transmitted irradiance can be derived from the measured full spectral irradiance and diffused spectral irradiance of atmosphere within visible spectrum (0.4-1.0μm). A method similar to that of King et al. which originally intended to apply to multi-wavelength measurements, is adopted to determine absorptive gaseous columnar amount from hyper spectrum. The solar irradiance at top of atmosphere and absorption coefficients of water vapor (H2O), ozone (O3), oxygen (O2) and nitrogen dioxide (NO2) are recalculated at an instrumental spectral resolution by convolution method. Based on the gaseous characteristics of absorption, the total columnar amounts of water vapor and oxygen are first inferred from solar transmitted irradiance at strong absorption wavelength of 0.934μm and 0.763μm respectively. The total columnar amounts of ozone and nitrogen dioxide, together with aerosol optical depth, are determined by a nonlinear least distance fitting method which minimizes a χ2 statistic to obtain optimal solutions. ASRAI was deployed for observation in Dunhuang site in China in August of 2014. Our results demonstrate that the algorithm is reasonable. Although the validation is preliminary, the hyper spectrum measured by ASRAI exhibits good ability to retrieve the abundance of absorptive gases and aerosols.

  8. High-resolution discrete absorption spectrum of α-methallyl free radical in the vapor phase

    NASA Astrophysics Data System (ADS)

    Bayrakçeken, Fuat; Telatar, Ziya; Arı, Fikret; Tunçyürek, Lale; Karaaslan, İpek; Yaman, Ali

    2006-09-01

    The α-methallyl free radical is formed in the flash photolysis of 3-methylbut-1-ene, and cis-pent-2-ene in the vapor phase, and then subsequent reactions have been investigated by kinetic spectroscopy and gas-liquid chromatography. The photolysis flash was of short duration and it was possible to follow the kinetics of the radicals' decay, which occurred predominantly by bimolecular recombination. The measured rate constant for the α-methallyl recombination was (3.5 ± 0.3) × 10 10 mol -1 l s -1 at 295 ± 2 K. The absolute extinction coefficients of the α-methallyl radical are calculated from the optical densities of the absorption bands. Detailed analysis of related absorption bands and lifetime measurements in the original α-methallyl high-resolution discrete absorption spectrum image were also carried out by image processing techniques.

  9. H i Absorption in the Steep-Spectrum Superluminal Quasar 3C 216.

    PubMed

    Pihlström; Vermeulen; Taylor; Conway

    1999-11-01

    The search for H i absorption in strong compact steep-spectrum sources is a natural way to probe the neutral gas contents in young radio sources. In turn, this may provide information about the evolution of powerful radio sources. The recently improved capabilities of the Westerbork Synthesis Radio Telescope have made it possible to detect a 0.31% (19 mJy) deep neutral atomic hydrogen absorption line associated with the steep-spectrum superluminal quasar 3C 216. The redshift (z=0.67) of the source shifts the frequency of the 21 cm line down to the ultra-high-frequency (UHF) band (850 MHz). The exact location of the H i-absorbing gas remains to be determined by spectral line VLBI observations at 850 MHz. We cannot exclude that the gas might be extended on galactic scales, but we think it is more likely to be located in the central kiloparsec. Constraints from the lack of X-ray absorption probably rule out obscuration of the core region, and we argue that the most plausible site for the H i absorption is in the jet-cloud interaction observed in this source.

  10. A variable absorption feature in the X-ray spectrum of a magnetar.

    PubMed

    Tiengo, Andrea; Esposito, Paolo; Mereghetti, Sandro; Turolla, Roberto; Nobili, Luciano; Gastaldello, Fabio; Götz, Diego; Israel, Gian Luca; Rea, Nanda; Stella, Luigi; Zane, Silvia; Bignami, Giovanni F

    2013-08-15

    Soft-γ-ray repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are slowly rotating, isolated neutron stars that sporadically undergo episodes of long-term flux enhancement (outbursts) generally accompanied by the emission of short bursts of hard X-rays. This behaviour can be understood in the magnetar model, according to which these sources are mainly powered by their own magnetic energy. This is supported by the fact that the magnetic fields inferred from several observed properties of SGRs and AXPs are greater than-or at the high end of the range of-those of radio pulsars. In the peculiar case of SGR 0418+5729, a weak dipole magnetic moment is derived from its timing parameters, whereas a strong field has been proposed to reside in the stellar interior and in multipole components on the surface. Here we show that the X-ray spectrum of SGR 0418+5729 has an absorption line, the properties of which depend strongly on the star's rotational phase. This line is interpreted as a proton cyclotron feature and its energy implies a magnetic field ranging from 2 × 10(14) gauss to more than 10(15) gauss. PMID:23955229

  11. A variable absorption feature in the X-ray spectrum of a magnetar.

    PubMed

    Tiengo, Andrea; Esposito, Paolo; Mereghetti, Sandro; Turolla, Roberto; Nobili, Luciano; Gastaldello, Fabio; Götz, Diego; Israel, Gian Luca; Rea, Nanda; Stella, Luigi; Zane, Silvia; Bignami, Giovanni F

    2013-08-15

    Soft-γ-ray repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are slowly rotating, isolated neutron stars that sporadically undergo episodes of long-term flux enhancement (outbursts) generally accompanied by the emission of short bursts of hard X-rays. This behaviour can be understood in the magnetar model, according to which these sources are mainly powered by their own magnetic energy. This is supported by the fact that the magnetic fields inferred from several observed properties of SGRs and AXPs are greater than-or at the high end of the range of-those of radio pulsars. In the peculiar case of SGR 0418+5729, a weak dipole magnetic moment is derived from its timing parameters, whereas a strong field has been proposed to reside in the stellar interior and in multipole components on the surface. Here we show that the X-ray spectrum of SGR 0418+5729 has an absorption line, the properties of which depend strongly on the star's rotational phase. This line is interpreted as a proton cyclotron feature and its energy implies a magnetic field ranging from 2 × 10(14) gauss to more than 10(15) gauss.

  12. [Methane optic fiber sensor network based on infrared spectrum absorption in coal mine].

    PubMed

    Wu, Xiao-jun; Wang, Peng; Wang, Zhi-bin; Li, Xiao; Tian, Er-ming

    2009-09-01

    Through analyzing the infrared absorption spectrum of methane, a multi-point optic fiber sensor network was designed based on the principle of light absorbing capability of gas which varies with gas concentration at its characteristic wavelength A distributed feedback laser diode (DFB LD) was used as the light source and an InGaAs PIN as the photodetector which features high sensitivity and low noise. Sixteen methane sensors were multiplexed in this system with space division multiple access technology (SDMAT), and the faint signals were processed by the filtering and amplifying circuit. All signals were gathered by the PCI data acquisition card, and finally, the signals were analyzed by the fast Fourier transform with software. The results showed that the sensitivity of every sensor reached 200 ppm (microg x mL(-1)), long-time accuracy and stability of all sensors could meet the practical demands, the response time of each sensor was less than 2 seconds and the detecting period was less than 32 seconds. By theoretical analysis, all sensors could be put in the mine at least 20 km from the ground, and the instruments could be applied to multi-point measurement at real-time in multiple occasions. PMID:19950630

  13. Schizophrenia Spectrum Disorders Show Reduced Specificity and Less Positive Events in Mental Time Travel

    PubMed Central

    Chen, Xing-jie; Liu, Lu-lu; Cui, Ji-fang; Wang, Ya; Chen, An-tao; Li, Feng-hua; Wang, Wei-hong; Zheng, Han-feng; Gan, Ming-yuan; Li, Chun-qiu; Shum, David H. K.; Chan, Raymond C. K.

    2016-01-01

    Mental time travel refers to the ability to recall past events and to imagine possible future events. Schizophrenia (SCZ) patients have problems in remembering specific personal experiences in the past and imagining what will happen in the future. This study aimed to examine episodic past and future thinking in SCZ spectrum disorders including SCZ patients and individuals with schizotypal personality disorder (SPD) proneness who are at risk for developing SCZ. Thirty-two SCZ patients, 30 SPD proneness individuals, and 33 healthy controls participated in the study. The Sentence Completion for Events from the Past Test (SCEPT) and the Sentence Completion for Events in the Future Test were used to measure past and future thinking abilities. Results showed that SCZ patients showed significantly reduced specificity in recalling past and imagining future events, they generated less proportion of specific and extended events compared to healthy controls. SPD proneness individuals only generated less extended events compared to healthy controls. The reduced specificity was mainly manifested in imagining future events. Both SCZ patients and SPD proneness individuals generated less positive events than controls. These results suggest that mental time travel impairments in SCZ spectrum disorders and have implications for understanding their cognitive and emotional deficits. PMID:27507958

  14. Schizophrenia Spectrum Disorders Show Reduced Specificity and Less Positive Events in Mental Time Travel.

    PubMed

    Chen, Xing-Jie; Liu, Lu-Lu; Cui, Ji-Fang; Wang, Ya; Chen, An-Tao; Li, Feng-Hua; Wang, Wei-Hong; Zheng, Han-Feng; Gan, Ming-Yuan; Li, Chun-Qiu; Shum, David H K; Chan, Raymond C K

    2016-01-01

    Mental time travel refers to the ability to recall past events and to imagine possible future events. Schizophrenia (SCZ) patients have problems in remembering specific personal experiences in the past and imagining what will happen in the future. This study aimed to examine episodic past and future thinking in SCZ spectrum disorders including SCZ patients and individuals with schizotypal personality disorder (SPD) proneness who are at risk for developing SCZ. Thirty-two SCZ patients, 30 SPD proneness individuals, and 33 healthy controls participated in the study. The Sentence Completion for Events from the Past Test (SCEPT) and the Sentence Completion for Events in the Future Test were used to measure past and future thinking abilities. Results showed that SCZ patients showed significantly reduced specificity in recalling past and imagining future events, they generated less proportion of specific and extended events compared to healthy controls. SPD proneness individuals only generated less extended events compared to healthy controls. The reduced specificity was mainly manifested in imagining future events. Both SCZ patients and SPD proneness individuals generated less positive events than controls. These results suggest that mental time travel impairments in SCZ spectrum disorders and have implications for understanding their cognitive and emotional deficits. PMID:27507958

  15. 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.

  16. Detection of the 1400 A absorption in the ultraviolet spectrum of the DA white dwarf LB 3303

    NASA Technical Reports Server (NTRS)

    Wegner, G.

    1982-01-01

    Low-resolution ultraviolet International Ultraviolet Explorer spectra of the southern white dwarf LB 3303 show the presence of the wavelength 1400 absorption feature reported by Greenstein in the spectrum of 40 Eri B. The equivalent width is 5.7 A, and the measured wavelength is 1394 A. A comparison of the ultraviolet fluxes with model atmospheres confirms that LB 3303 has an effective temperature near 16,000 K, as found earlier from visual wavelength data. There are still problems with the identification of this line. The star is not hot enough to explain the presence of Si IV, and the agreement with the spectrum of the H2 molecule is not convincing.

  17. NF3: UV Absorption Spectrum Temperature Dependence and the Atmospheric and Climate Forcing Implications

    NASA Technical Reports Server (NTRS)

    Papadimitriou, Vassileios C.; McGillen, Max R.; Fleming, Eric L.; Jackman, Charles H.; Burkholder, James B.

    2013-01-01

    Nitrogen trifluoride (NF3) is an atmospherically persistent greenhouse gas that is primarily removed by UV photolysis and reaction with O((sup 1)D) atoms. In this work, the NF3 gas-phase UV absorption spectrum, sigma(delta,T), was measured at 16 wavelengths between 184.95 and 250 nm at temperatures between 212 and 296 K. A significant spectrum temperature dependence was observed in the wavelength region most relevant to atmospheric photolysis (200-220 nm) with a decrease in sigma(210 nm,T) of approximately 45 percent between 296 and 212 K. Atmospheric photolysis rates and global annually averaged lifetimes of NF3 were calculated using the Goddard Space Flight Center 2-D model and the sigma(delta,T) parameterization developed in this work. Including the UV absorption spectrum temperature dependence increased the stratospheric photolysis lifetime from 610 to 762 years and the total global lifetime from 484 to 585 years; the NF3 global warming potentials on the 20-, 100-, and 500-year time horizons increased less than 0.3, 1.1, and 6.5 percent to 13,300, 17,700, and 19,700, respectively.

  18. 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.

  19. Surprises from a Deep ASCA Spectrum of the Broad Absorption Line Quasar PHL 5200

    NASA Technical Reports Server (NTRS)

    Mathur, Smita; Matt, G.; Green, P. J.; Elvis, M.; Singh, K. P.

    2002-01-01

    We present a deep (approx. 85 ks) ASCA observation of the prototype broad absorption line quasar (BALQSO) PHL 5200. This is the best X-ray spectrum of a BALQSO yet. We find the following: (1) The source is not intrinsically X-ray weak. (2) The line-of-sight absorption is very strong, with N(sub H) = 5 x 10(exp 23)/sq cm. (3) The absorber does not cover the source completely; the covering fraction is approx. 90%. This is consistent with the large optical polarization observed in this source, implying multiple lines of sight. The most surprising result of this observation is that (4) the spectrum of this BALQSO is not exactly similar to other radio-quiet quasars. The hard X-ray spectrum of PHL 5200 is steep, with the power-law spectral index alpha approx. 1.5. This is similar to the steepest hard X-ray slopes observed so far. At low redshifts, such steep slopes are observed in narrow-line Seyfert 1 (NLS1) galaxies, believed to be accreting at a high Eddington rate. This observation strengthens the analogy between BALQSOs and NLS1 galaxies and supports the hypothesis that BALQSOs represent an early evolutionary state of quasars. It is well accepted that the orientation to the line of sight determines the appearance of a quasar: age seems to play a significant role as well.

  20. Simulation of energy absorption spectrum in NaI crystal detector for multiple gamma energy using Monte Carlo method

    SciTech Connect

    Wirawan, Rahadi; Waris, Abdul; Djamal, Mitra; Handayani, Gunawan

    2015-04-16

    The spectrum of gamma energy absorption in the NaI crystal (scintillation detector) is the interaction result of gamma photon with NaI crystal, and it’s associated with the photon gamma energy incoming to the detector. Through a simulation approach, we can perform an early observation of gamma energy absorption spectrum in a scintillator crystal detector (NaI) before the experiment conducted. In this paper, we present a simulation model result of gamma energy absorption spectrum for energy 100-700 keV (i.e. 297 keV, 400 keV and 662 keV). This simulation developed based on the concept of photon beam point source distribution and photon cross section interaction with the Monte Carlo method. Our computational code has been successfully predicting the multiple energy peaks absorption spectrum, which derived from multiple photon energy sources.

  1. Effect of Sn on the optical band gap determined using absorption spectrum fitting method

    SciTech Connect

    Heera, Pawan; Kumar, Anup; Sharma, Raman

    2015-05-15

    We report the preparation and the optical studies on tellurium rich glasses thin films. The thin films of Se{sub 30}Te{sub 70-x} Sn{sub x} system for x= 0, 1.5, 2.5 and 4.5 glassy alloys prepared by melt quenching technique are deposited on the glass substrate using vacuum thermal evaporation technique. The analysis of absorption spectra in the spectral range 400nm–4000 nm at room temperature obtained from UV-VIS-NIR spectrophotometer [Perkin Elmer Lamda-750] helps us in the optical characterization of the thin films under study. The absorption spectrum fitting method is applied by using the Tauc’s model for estimating the optical band gap and the width of the band tail of the thin films. The optical band gap is calculated and is found to decrease with the Sn content.

  2. Investigations on the 1.7 micron residual absorption feature in the vegetation reflection spectrum

    NASA Technical Reports Server (NTRS)

    Verdebout, J.; Jacquemoud, S.; Andreoli, G.; Hosgood, B.; Sieber, A.

    1993-01-01

    The detection and interpretation of the weak absorption features associated with the biochemical components of vegetation is of great potential interest to a variety of applications ranging from classification to global change studies. This recent subject is also challenging because the spectral signature of the biochemicals is only detectable as a small distortion of the infrared spectrum which is mainly governed by water. Furthermore, the interpretation is complicated by complexity of the molecules (lignin, cellulose, starch, proteins) which contain a large number of different and common chemical bonds. In this paper, we present investigations on the absorption feature centered at 1.7 micron; these were conducted both on AVIRIS data and laboratory reflectance spectra of leaves.

  3. UV absorption spectrum and photodissociation channels of the simplest Criegee intermediate (CH2OO).

    PubMed

    Dawes, Richard; Jiang, Bin; Guo, Hua

    2015-01-14

    The lowest-lying singlet states of the simplest Criegee intermediate (CH2OO) have been characterized along the O-O dissociation coordinate using explicitly correlated MRCI-F12 electronic structure theory and large active spaces. It is found that a high-level treatment of dynamic electron-correlation is essential to accurately describe these states. A significant well on the B-state is identified at the MRCI-F12 level with an equilibrium structure that differs substantially from that of the ground X-state. This well is presumably responsible for the apparent vibrational structure in some experimental UV absorption spectra, analogous to the structured Huggins band of the iso-electronic ozone. The B-state potential in the Franck-Condon region is sufficiently accurate that an absorption spectrum calculated with a one-dimensional model agrees remarkably well with experiment.

  4. Atmospheric degradation of pyridine: UV absorption spectrum and reaction with OH radicals and O3

    NASA Astrophysics Data System (ADS)

    Errami, M.; El Dib, G.; Cazaunau, M.; Roth, E.; Salghi, R.; Mellouki, A.; Chakir, A.

    2016-10-01

    The UV absorption spectrum of pyridine and its gas phase reactions with OH radicals and O3 were investigated. UV absorption cross-sections were determined by using a D2-lamp system in the range 200-350 nm. The kinetic studies were carried out at room temperature and atmospheric pressure of purified air. The rate coefficient for the reaction of pyridine with OH was determined relative to that with acetone while that with O3 was measured under pseudo first order conditions. The rate coefficients obtained are (in cm3 molecule-1 s-1): k(OH + pyridine) = (5.40 ± 0.80) × 10-13 and k(O3 + pyridine) = (3.28 ± 1.70) × 10-20.

  5. Do Children with Autism Spectrum Disorders Show a Shape Bias in Word Learning?

    PubMed Central

    Tek, Saime; Jaffery, Gul; Fein, Deborah; Naigles, Letitia R.

    2009-01-01

    Many children with autism spectrum disorders (ASD) acquire a sizeable lexicon. However, these children also seem to understand and/or store the meanings of words differently from typically developing children. One of the mechanisms that helps typically developing children learn novel words is the shape bias, in which the referent of a noun is mapped onto the shape of an object, rather than onto its color, texture, or size. We hypothesized that children with Autistic Disorder would show reduced or absent shape bias. Using the Intermodal Preferential Looking Paradigm (IPL), we compared the performance of young children with ASD and typically developing children (TYP), across four time points, in their use of shape bias. Neither group showed a shape bias at Visit 1, when half of the children in both groups produced fewer than 50 count nouns. Only the TYP group showed a shape bias at Visits 2, 3, and 4. According to growth curve analyses, the rate of increase in the shape bias scores over time was significant for the TYP children. The fact that the TYP group showed a shape bias at 24 months of age, whereas children with ASD did not demonstrate a shape bias despite a sizeable vocabulary, supports a dissociation between vocabulary size and principles governing acquisition in ASD children from early in language development. PMID:19360671

  6. The absorption spectrum of NH 2 in the region 5300 to 6800 Å

    NASA Astrophysics Data System (ADS)

    Ross, S. C.; Birss, F. W.; Vervloet, M.; Ramsay, D. A.

    1988-06-01

    The detailed analysis of the Ã2A 1- X˜2B 1 spectrum of NH 2 in the region 5300 to 6800 Å is reported. Term values derived from the analysis are also presented. Numerous new vibronic substates have been identified. The assignment of the substates and the perturbations detected are discussed in detail, making reference to the calculations of Jungen, Hallin, and Merer and also drawing on the argon matrix absorption spectrum of Robinson and McCarty. The parameters of a simplified model Hamiltonian are reported for most of the substates. The comparison of these results to the calculations of Jungen, Hallin, and Merer, along with the tendencies in the behavior of the spin-orbit coupling constant detected in their work, facilitated the assignments in the present work.

  7. Total Absorption Spectroscopy Study of (92)Rb Decay: A Major Contributor to Reactor Antineutrino Spectrum Shape.

    PubMed

    Zakari-Issoufou, A-A; Fallot, M; Porta, A; Algora, A; Tain, J L; Valencia, E; Rice, S; Bui, V M; Cormon, S; Estienne, M; Agramunt, J; Äystö, J; Bowry, M; Briz, J A; Caballero-Folch, R; Cano-Ott, D; Cucoanes, A; Elomaa, V-V; Eronen, T; Estévez, E; Farrelly, G F; Garcia, A R; Gelletly, W; Gomez-Hornillos, M B; Gorlychev, V; Hakala, J; Jokinen, A; Jordan, M D; Kankainen, A; Karvonen, P; Kolhinen, V S; Kondev, F G; Martinez, T; Mendoza, E; Molina, F; Moore, I; Perez-Cerdán, A B; Podolyák, Zs; Penttilä, H; Regan, P H; Reponen, M; Rissanen, J; Rubio, B; Shiba, T; Sonzogni, A A; Weber, C

    2015-09-01

    The antineutrino spectra measured in recent experiments at reactors are inconsistent with calculations based on the conversion of integral beta spectra recorded at the ILL reactor. (92)Rb makes the dominant contribution to the reactor antineutrino spectrum in the 5-8 MeV range but its decay properties are in question. We have studied (92)Rb decay with total absorption spectroscopy. Previously unobserved beta feeding was seen in the 4.5-5.5 region and the GS to GS feeding was found to be 87.5(25)%. The impact on the reactor antineutrino spectra calculated with the summation method is shown and discussed. PMID:26382674

  8. Total Absorption Spectroscopy Study of 92Rb Decay: A Major Contributor to Reactor Antineutrino Spectrum Shape

    NASA Astrophysics Data System (ADS)

    Zakari-Issoufou, A.-A.; Fallot, M.; Porta, A.; Algora, A.; Tain, J. L.; Valencia, E.; Rice, S.; Bui, V. M.; Cormon, S.; Estienne, M.; Agramunt, J.; ńystö, J.; Bowry, M.; Briz, J. A.; Caballero-Folch, R.; Cano-Ott, D.; Cucoanes, A.; Elomaa, V.-V.; Eronen, T.; Estévez, E.; Farrelly, G. F.; Garcia, A. R.; Gelletly, W.; Gomez-Hornillos, M. B.; Gorlychev, V.; Hakala, J.; Jokinen, A.; Jordan, M. D.; Kankainen, A.; Karvonen, P.; Kolhinen, V. S.; Kondev, F. G.; Martinez, T.; Mendoza, E.; Molina, F.; Moore, I.; Perez-Cerdán, A. B.; Podolyák, Zs.; Penttilä, H.; Regan, P. H.; Reponen, M.; Rissanen, J.; Rubio, B.; Shiba, T.; Sonzogni, A. A.; Weber, C.

    2015-09-01

    The antineutrino spectra measured in recent experiments at reactors are inconsistent with calculations based on the conversion of integral beta spectra recorded at the ILL reactor. 92Rb makes the dominant contribution to the reactor antineutrino spectrum in the 5-8 MeV range but its decay properties are in question. We have studied 92Rb decay with total absorption spectroscopy. Previously unobserved beta feeding was seen in the 4.5-5.5 region and the GS to GS feeding was found to be 87.5(25)%. The impact on the reactor antineutrino spectra calculated with the summation method is shown and discussed.

  9. [The effect of Doppler effect on ultraviolet absorption spectrum from difference in temperature (UVASDT)].

    PubMed

    Hu, Yao-gai; Zeng, Fan-qing; Li, Wei; Hu, Ji-ming

    2005-06-01

    In this paper, the formation of UV absorption spectrum from difference in temperature (UVASDT) is discussed. Broadening of spectral lines might be one of the reasons for the formation of UVASDT. The effect of temperature on the broadening of spectral lines is analyzed. The Doppler SDT function is deduced, and the SDT of C60 and progesterone can be explained by it. It is indicated that the Doppler effect might be the primary reason for the formation of UVASDT of this kind of substance.

  10. Modelling warm absorption in HST/COS spectrum of Mrk 290 with XSTAR

    NASA Astrophysics Data System (ADS)

    Zhang, S. N.; Ji, L.; Kallman, T. R.; Yao, Y. S.; Froning, C. S.; Gu, Q. S.; Kriss, G. A.

    2015-03-01

    We present a new method to model an HST/COS (Hubble Space Telescope/Cosmic Origins Spectrograph) spectrum, aimed to analyse intrinsic UV absorption from the outflow of Mrk 290, a Seyfert I galaxy. We use newly updated XSTAR to generate photoionization models for the intrinsic absorption from the active galactic nuclei (AGN) outflow, the line emission from the AGN broad- and narrow-line regions, and the local absorption from high-velocity clouds and Galactic interstellar medium. The combination of these physical models accurately fits the COS spectrum. Three intrinsic absorbers outflowing with velocities ˜500 km s- 1 are identified, two of which are found directly from two velocity components of the N V and C IV doublets, while the third is required by the extra absorption in the Lyα. Their outflow velocities, ionization states and column densities are consistent with the lowest and moderate ionization warm absorbers (WAs) in the X-ray domain found by Chandra observations, suggesting a one-to-one correspondence between the absorbing gas in the UV and X-ray bands. The small turbulent velocities of the WAs (vturb ≲ 100 km s- 1) support our previous argument from the X-ray study that the absorbers originate from the inner side of the torus due to thermal evaporation. Given the covering fractions of ˜65 per cent for the three WAs, we deduce that the lengths and the thicknesses of the WAs are comparable, which indicates that the geometry of WAs are more likely clouds rather than flat and thin layers. In addition, the modelling of the broad-line emission suggests a higher covering fraction of clouds when they are very closer to the black hole.

  11. CFCI3 (CFC-11): UV Absorption Spectrum Temperature Dependence Measurements and the Impact on Atmospheric Lifetime and Uncertainty

    NASA Technical Reports Server (NTRS)

    Mcgillen, Max R.; Fleming, Eric L.; Jackman, Charles H.; Burkholder, James B.

    2014-01-01

    CFCl3 (CFC-11) is both an atmospheric ozone-depleting and potent greenhouse gas that is removed primarily via stratospheric UV photolysis. Uncertainty in the temperature dependence of its UV absorption spectrum is a significant contributing factor to the overall uncertainty in its global lifetime and, thus, model calculations of stratospheric ozone recovery and climate change. In this work, the CFC-11 UV absorption spectrum was measured over a range of wavelength (184.95 - 230 nm) and temperature (216 - 296 K). We report a spectrum temperature dependence that is less than currently recommended for use in atmospheric models. The impact on its atmospheric lifetime was quantified using a 2-D model and the spectrum parameterization developed in this work. The obtained global annually averaged lifetime was 58.1 +- 0.7 years (2 sigma uncertainty due solely to the spectrum uncertainty). The lifetime is slightly reduced and the uncertainty significantly reduced from that obtained using current spectrum recommendations

  12. CFCl3 (CFC-11): UV absorption spectrum temperature dependence measurements and the impact on its atmospheric lifetime and uncertainty

    NASA Astrophysics Data System (ADS)

    McGillen, Max R.; Fleming, Eric L.; Jackman, Charles H.; Burkholder, James B.

    2013-09-01

    (CFC-11) is both an atmospheric ozone-depleting and potent greenhouse gas that is removed primarily via stratospheric UV photolysis. Uncertainty in the temperature dependence of its UV absorption spectrum is a significant contributing factor to the overall uncertainty in its global lifetime and, thus, model calculations of stratospheric ozone recovery and climate change. In this work, the CFC-11 UV absorption spectrum was measured over a range of wavelength (184.95-230 nm) and temperature (216-296 K). We report a spectrum temperature dependence that is less than that currently recommended for use in atmospheric models. The impact on its atmospheric lifetime was quantified using a 2-D model and the spectrum parameterization developed in this work. The calculated global annually averaged lifetime was 58.1 ± 0.7 years (2σ uncertainty due solely to the spectrum uncertainty). The lifetime is slightly reduced and the uncertainty significantly reduced from that obtained using current UV spectrum recommendations.

  13. Dynamic registration of D216O absorption spectrum in silica aerogel

    NASA Astrophysics Data System (ADS)

    Sinitsa, L.; Lavrentieva, N.; Lugovskoi, A.

    2014-09-01

    Absorption spectra of the gas phase and adsorbed D2О in the silica aerogel with nanoscale pores were investigated in 3700-5400 cm-1 range using dynamic registration with Fourier Transform spectrometer IFS-125M. Two types of sample with pores of 60 nm wide - the nitrogen gas-treated and untreated aerogels - were examined. The surface treatment of the sample changes noticeably the broadband absorption of adsorbed water. Spectrum of D2O in the pores differs from the spectrum of bulk water as for bandwidth so for band maximum. It was found that treatment of the pores by dry nitrogen leads to increasing hydrophilic properties of the material and to change water band contour. The D2О line widths in both the aerogels exceed those of free monomer in 1.1-3 times at the same pressure. Calculations of self-broadening coefficients of the D2O lines were performed using semi-empirical method based on the impact theory of broadening and includes the correction factors. The calculated results well agree with experimental data. Greater differences were found for the shift of the line centre. The D2O line shifts in the treated pores significantly exceed line shifts in the untreated pores. For some lines, these shifts have the opposite sign indicating complex nature of the molecule-wall interaction.

  14. Frequency-domain method for measuring spectral properties in multiple-scattering media: methemoglobin absorption spectrum in a tissuelike phantom

    NASA Astrophysics Data System (ADS)

    Fishkin, Joshua B.; So, Peter T. C.; Cerussi, Albert E.; Gratton, Enrico; Fantini, Sergio; Franceschini, Maria Angela

    1995-03-01

    We have measured the optical absorption and scattering coefficient spectra of a multiple-scattering medium (i.e., a biological tissue-simulating phantom comprising a lipid colloid) containing methemoglobin by using frequency-domain techniques. The methemoglobin absorption spectrum determined in the multiple-scattering medium is in excellent agreement with a corrected methemoglobin absorption spectrum obtained from a steady-state spectrophotometer measurement of the optical density of a minimally scattering medium. The determination of the corrected methemoglobin absorption spectrum takes into account the scattering from impurities in the methemoglobin solution containing no lipid colloid. Frequency-domain techniques allow for the separation of the absorbing from the scattering properties of multiple-scattering media, and these techniques thus provide an absolute

  15. 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. PMID:24016295

  16. Nile blue shows its true colors in gas-phase absorption and luminescence ion spectroscopy.

    PubMed

    Stockett, M H; Houmøller, J; Brøndsted Nielsen, S

    2016-09-14

    Nile blue is used extensively in biology as a histological stain and fluorescent probe. Its absorption and emission spectra are strongly solvent dependent, with variations larger than 100 nm. The molecule is charged due to an iminium group, and it is therefore an obvious target for gas-phase ion spectroscopy. Here we report the absorption and emission spectra of the mass-selected bare ions isolated in vacuo, and based on our results we revisit the interpretation of solution-phase spectra. An accelerator mass spectrometer was used for absorption spectroscopy where the absorption is represented by the yield of photofragment ions versus excitation wavelength (action spectroscopy). The luminescence experiments were done with a newly built ion trap setup equipped with an electrospray ion source, and some details on the mass selection technique will be given which have not been described before. In vacuo, the absorption and emission maxima are at 580 ± 10 nm and 628 ± 1 nm. These values are somewhat blue-shifted relative to those obtained in most solvents; however, they are much further to the red than those in some of the most non-polar solvents. Furthermore, the Stokes shift in the gas phase (1300 cm(-1)) is much smaller than that in these non-polar solvents but similar to that in polar ones. An explanation based on charge localization by solvent dipoles, or by counterions in some non-polar solvents, can fully account for these findings. Hence in the case of ions, it is nontrivial to establish intrinsic electronic transition energies from solvatochromic shifts alone. PMID:27634256

  17. Nile blue shows its true colors in gas-phase absorption and luminescence ion spectroscopy.

    PubMed

    Stockett, M H; Houmøller, J; Brøndsted Nielsen, S

    2016-09-14

    Nile blue is used extensively in biology as a histological stain and fluorescent probe. Its absorption and emission spectra are strongly solvent dependent, with variations larger than 100 nm. The molecule is charged due to an iminium group, and it is therefore an obvious target for gas-phase ion spectroscopy. Here we report the absorption and emission spectra of the mass-selected bare ions isolated in vacuo, and based on our results we revisit the interpretation of solution-phase spectra. An accelerator mass spectrometer was used for absorption spectroscopy where the absorption is represented by the yield of photofragment ions versus excitation wavelength (action spectroscopy). The luminescence experiments were done with a newly built ion trap setup equipped with an electrospray ion source, and some details on the mass selection technique will be given which have not been described before. In vacuo, the absorption and emission maxima are at 580 ± 10 nm and 628 ± 1 nm. These values are somewhat blue-shifted relative to those obtained in most solvents; however, they are much further to the red than those in some of the most non-polar solvents. Furthermore, the Stokes shift in the gas phase (1300 cm(-1)) is much smaller than that in these non-polar solvents but similar to that in polar ones. An explanation based on charge localization by solvent dipoles, or by counterions in some non-polar solvents, can fully account for these findings. Hence in the case of ions, it is nontrivial to establish intrinsic electronic transition energies from solvatochromic shifts alone.

  18. Nile blue shows its true colors in gas-phase absorption and luminescence ion spectroscopy

    NASA Astrophysics Data System (ADS)

    Stockett, M. H.; Houmøller, J.; Brøndsted Nielsen, S.

    2016-09-01

    Nile blue is used extensively in biology as a histological stain and fluorescent probe. Its absorption and emission spectra are strongly solvent dependent, with variations larger than 100 nm. The molecule is charged due to an iminium group, and it is therefore an obvious target for gas-phase ion spectroscopy. Here we report the absorption and emission spectra of the mass-selected bare ions isolated in vacuo, and based on our results we revisit the interpretation of solution-phase spectra. An accelerator mass spectrometer was used for absorption spectroscopy where the absorption is represented by the yield of photofragment ions versus excitation wavelength (action spectroscopy). The luminescence experiments were done with a newly built ion trap setup equipped with an electrospray ion source, and some details on the mass selection technique will be given which have not been described before. In vacuo, the absorption and emission maxima are at 580 ± 10 nm and 628 ± 1 nm. These values are somewhat blue-shifted relative to those obtained in most solvents; however, they are much further to the red than those in some of the most non-polar solvents. Furthermore, the Stokes shift in the gas phase (1300 cm-1) is much smaller than that in these non-polar solvents but similar to that in polar ones. An explanation based on charge localization by solvent dipoles, or by counterions in some non-polar solvents, can fully account for these findings. Hence in the case of ions, it is nontrivial to establish intrinsic electronic transition energies from solvatochromic shifts alone.

  19. Magnetoencephalography shows atypical sensitivity to linguistic sound sequences in autism spectrum disorder.

    PubMed

    Brennan, Jonathan R; Wagley, Neelima; Kovelman, Ioulia; Bowyer, Susan M; Richard, Annette E; Lajiness-O'Neill, Renee

    2016-09-01

    Neuroscientific evidence points toward atypical auditory processing in individuals with autism spectrum disorders (ASD), and yet, the consequences of this for receptive language remain unclear. Using magnetoencephalography and a passive listening task, we test for cascading effects on speech sound processing. Children with ASD and age-matched control participants (8-12 years old) listened to nonce linguistic stimuli that either did or did not conform to the phonological rules that govern consonant sequences in English (e.g. legal 'vimp' vs. illegal 'vimk'). Beamformer source analysis was used to isolate evoked responses (0.1-30 Hz) to these stimuli in the left and the right auditory cortex. Right auditory responses from participants with ASD, but not control participants, showed an attenuated response to illegal sequences relative to legal sequences that emerged around 330 ms after the onset of the critical phoneme. These results suggest that phonological processing is impacted in ASD, perhaps because of cascading effects from disrupted initial acoustic processing. PMID:27468112

  20. Absorption spectrum of an atom strongly coupled to a high-temperature reservoir

    NASA Astrophysics Data System (ADS)

    Kofman, A. G.

    2005-03-01

    We study the absorption spectrum of a weak probe field near resonant to an atomic transition, the upper level of which is strongly coupled to a third level by the interaction with a Lorentzian bosonic reservoir, such as, e.g., a mode of a high- Q cavity or a local vibration in a solid. The reservoir coupling is approximated by the interaction with a classical complex Gaussian-Markovian random process (control field), which is justified when the reservoir temperature exceeds significantly the mode frequency or when the high- Q cavity is pumped by broadband incoherent radiation. The present theory is applicable also when the control field is chaotic laser light. We assume that the rms control-field Rabi frequency V0 is much greater than the field detuning Δc , which, in turn, is much greater than the material relaxation constants. We reveal and describe analytically all qualitatively different regimes of the spectrum modification and obtain their validity conditions. The analytical results are verified by numerical calculations using the exact continued-fraction solution. The analytical formulas obtained allow one to perform fast computer calculations for arbitrarily small values of the reservoir (control-field) bandwidth ν , in contrast to the known numerical methods, which require sharply increasing computational resources with a decrease of ν . In the most interesting case ν≪V0 , the spectrum consists of two peaks, the nonvanishing bandwidth and material relaxation affecting mainly the dip between the peaks. The results obtained in the static limit (i.e., a very narrow reservoir) are independent of the reservoir band shape. We reveal reservoir-induced transparency (RIT)—i.e., absorption reduction due to the reservoir coupling. Moreover, two unexpected, remarkable features are uncovered in a range of intermediate values of ν and V0 , Γ2∣Δc∣≪V02ν≪∣Δc∣3 ( Γ is the spectral width in the absence of the control field): an extra peak in the dip

  1. [Study on transient absorption spectrum of tungsten nanoparticle with HepG2 tumor cell].

    PubMed

    Cao, Lin; Shu, Xiao-Ning; Liang, Dong; Wang, Cong

    2014-07-01

    Significance of this study lies in tungsten nano materials can be used as a preliminary innovative medicines applied basic research. This paper investigated the inhibition of tungsten nanoparticles which effected on human hepatoma HepG2 cells by MTT. The authors use transient absorption spectroscopy (TAS) technology absorption and emission spectra characterization of charge transfer between nanoparticles and tumor cell. The authors discussed the role of the tungsten nanoparticles in the tumor early detection of the disease and its anti-tumor properties. In the HepG2 experiments system, 100-150 microg x mL(-1) is the best drug concentration of anti-tumor activity which recact violently within 6 hours and basically completed in 24 hours. The results showed that transient absorption spectroscopy can be used as tumor detection methods and characterization of charge transfer between nano-biosensors and tumor cells. Tungsten nanoparticles have potential applications as anticancer drugs.

  2. Absorption features in the x-ray spectrum of an ordinary radio pulsar.

    PubMed

    Kargaltsev, Oleg; Durant, Martin; Misanovic, Zdenka; Pavlov, George G

    2012-08-24

    The vast majority of known nonaccreting neutron stars (NSs) are rotation-powered radio and/or γ-ray pulsars. So far, their multiwavelength spectra have all been described satisfactorily by thermal and nonthermal continuum models, with no spectral lines. Spectral features have, however, been found in a handful of exotic NSs and were thought to be a manifestation of their unique traits. Here, we report the detection of absorption features in the x-ray spectrum of an ordinary rotation-powered radio pulsar, J1740+1000. Our findings bridge the gap between the spectra of pulsars and other, more exotic, NSs, suggesting that the features are more common in the NS spectra than they have been thought so far.

  3. Theoretical reproduction of the Q-band absorption spectrum of free-base chlorin.

    PubMed

    Wójcik, Justyna; Ratuszna, Alicja; Peszke, Jerzy; Wrzalik, Roman

    2015-01-21

    The computational results of the features observed in the room-temperature Q-band absorption spectrum of free-base chlorin (H2Ch) are presented. The vibrational structures of the first and second excited singlet states were calculated based on a harmonic approximation using density functional theory and its time dependent extension within the Franck-Condon and Herzberg-Teller approaches. The outcome allowed to identify the experimental bands and to assign them to the specific vibrational transitions. A very good agreement between the simulated and measured wavelengths and their relative intensities provided the opportunity to predict the origin of the S0 → S2 transition which could not be determined experimentally.

  4. A combined experimental-computational study on nitrogen doped Cu2O as the wide-spectrum absorption material

    NASA Astrophysics Data System (ADS)

    Ping, Zhang; Yurong, Zhou; Qingbo, Yan; Fengzhen, Liu; Jingwen, Li; Gangqiang, Dong

    2014-10-01

    Highly-oriented Cu2O thin films were prepared by low temperature thermal oxidation of evaporated Cu thin films. The films were doped with different doses of nitrogen by ion implantation. An absorption peak appears below the absorption edge in the absorption spectrum of highly nitrogen doped Cu2O. The effect of nitrogen doping on the crystal structure, electronic structure and optical properties of Cu2O were investigated systematically by first-principles calculations. The calculation results indicate that an intermediate energy band exists in the forbidden gap of highly nitrogen doped Cu2O. The electron transition from the valence band to the intermediate band is consistent with the absorption peak by experimental observation. Experimental and computational results indicate that nitrogen doped Cu2O could be a suitable absorbing material candidate for wide-spectrum detectors or intermediate band solar cells.

  5. A universal feature in the optical absorption spectrum associated with hydrogenated amorphous silicon: A dimensionless joint density of states analysis

    NASA Astrophysics Data System (ADS)

    Thevaril, Jasmin J.; O'Leary, Stephen K.

    2016-10-01

    Using a dimensionless joint density of states formalism for the quantitative characterization of the optical response associated with hydrogenated amorphous silicon, a critical comparative analysis of a large number of different optical absorption data sets is considered. When these data sets are cast into this dimensionless framework, we observe a trend that is almost completely coincident for all of the data sets considered. This suggests that there is a universal feature associated with the optical absorption spectrum of hydrogenated amorphous silicon.

  6. A Giant Metrewave Radio Telescope search for associated H I 21 cm absorption in high-redshift flat-spectrum sources

    NASA Astrophysics Data System (ADS)

    Aditya, J. N. H. S.; Kanekar, Nissim; Kurapati, Sushma

    2016-02-01

    We report results from a Giant Metrewave Radio Telescope search for `associated' redshifted H I 21 cm absorption from 24 active galactic nuclei (AGNs), at 1.1 < z < 3.6, selected from the Caltech-Jodrell Bank Flat-spectrum (CJF) sample. 22 out of 23 sources with usable data showed no evidence of absorption, with typical 3σ optical depth detection limits of ≈0.01 at a velocity resolution of ≈30 km s-1. A single tentative absorption detection was obtained at z ≈ 3.530 towards TXS 0604+728. If confirmed, this would be the highest redshift at which H I 21 cm absorption has ever been detected. Including 29 CJF sources with searches for redshifted H I 21 cm absorption in the literature, mostly at z < 1, we construct a sample of 52 uniformly selected flat-spectrum sources. A Peto-Prentice two-sample test for censored data finds (at ≈3σ significance) that the strength of H I 21 cm absorption is weaker in the high-z sample than in the low-z sample; this is the first statistically significant evidence for redshift evolution in the strength of H I 21 cm absorption in a uniformly selected AGN sample. However, the two-sample test also finds that the H I 21 cm absorption strength is higher in AGNs with low ultraviolet or radio luminosities, at ≈3.4σ significance. The fact that the higher luminosity AGNs of the sample typically lie at high redshifts implies that it is currently not possible to break the degeneracy between AGN luminosity and redshift evolution as the primary cause of the low H I 21 cm opacities in high-redshift, high-luminosity AGNs.

  7. Total Absorption Spectroscopy Study of ⁹²Rb Decay: A Major Contributor to Reactor Antineutrino Spectrum Shape

    DOE PAGES

    Sonzogni, A.; Zakari-Issoufou, A. -A.; Fallot, M.; Porta, A.; Algora, A.; Tain, J. L.; Valencia, E.; Rice, S.; Bui, V. M.; Cormon, S.; et al

    2015-03-09

    The accurate determination of the emitted reactor antineutrino flux is still a major challenge for actual and future neutrino experiments at reactors, especially after the evidence of a disagreement between the measured antineutrino energy spectrum by Double Chooz, Daya Bay, and Reno and calculated antineutrino spectra obtained from the conversion of the unique integral beta spectra measured at the ILL reactor. Using nuclear data to compute reactor antineutrino spectra may help understanding this bias, with the study of the underlying nuclear physics. Summation calculations allow identifying a list of nuclei that contribute importantly to the antineutrino energy spectra emitted aftermore » the fission of ²³⁹,²⁴¹Pu and ²³⁵,²³⁸U, and whose beta decay properties might deserve new measurements. Among these nuclei, ⁹²Rb exhausts by itself about 16% of of the antineutrino energy spectrum emitted by Pressurized Water Reactors in the 5 to 8 MeV range. In this Letter, we report new Total Absorption Spectroscopy (TAS) results for this important contributor. The obtained beta feeding from ⁹²Rb shows beta intensity unobserved before in the 4.5 to 5.5 MeV energy region and gives a ground state to ground state branch of 87.5 % ± 3%. These new data induce a dramatic change in recent summation calculations where a 51% GS to GS branch was considered for ⁹²Rb, increasing the summation antineutrino spectrum in the region nearby the observed bias.The new data still have an important impact on other summation calculations in which more recent data were considered« less

  8. Total Absorption Spectroscopy Study of ⁹²Rb Decay: A Major Contributor to Reactor Antineutrino Spectrum Shape

    SciTech Connect

    Sonzogni, A.; Zakari-Issoufou, A. -A.; Fallot, M.; Porta, A.; Algora, A.; Tain, J. L.; Valencia, E.; Rice, S.; Bui, V. M.; Cormon, S.; Estienne, M.; Agramunt, J.; Aysto, J.; Bowry, M.; Briz Monago, J. A.; Caballero-Folch, R.; Cano-Ott, D.; Cucoanes, A.; Eloma, V.; Estvez, E.; Farrelly, G. F.; Garcia, A.; Gelletly, W.; Gomez-Hornillos, M. B.; Gorlychev, V.; Hakala, J.; Jokinen, A.; Jordan, M. D.; Kankainen, A.; Kondev, F. G.; Martinez, T.; Mendoza, E.; Molina, F.; Moore, I.; Perez, A.; Podolyak, Zs.; Penttil, H.; Regan, P. H.; Shiba, T.; Rissanen, J.; Rubio, B.; Weber, C.

    2015-03-09

    The accurate determination of the emitted reactor antineutrino flux is still a major challenge for actual and future neutrino experiments at reactors, especially after the evidence of a disagreement between the measured antineutrino energy spectrum by Double Chooz, Daya Bay, and Reno and calculated antineutrino spectra obtained from the conversion of the unique integral beta spectra measured at the ILL reactor. Using nuclear data to compute reactor antineutrino spectra may help understanding this bias, with the study of the underlying nuclear physics. Summation calculations allow identifying a list of nuclei that contribute importantly to the antineutrino energy spectra emitted after the fission of ²³⁹,²⁴¹Pu and ²³⁵,²³⁸U, and whose beta decay properties might deserve new measurements. Among these nuclei, ⁹²Rb exhausts by itself about 16% of of the antineutrino energy spectrum emitted by Pressurized Water Reactors in the 5 to 8 MeV range. In this Letter, we report new Total Absorption Spectroscopy (TAS) results for this important contributor. The obtained beta feeding from ⁹²Rb shows beta intensity unobserved before in the 4.5 to 5.5 MeV energy region and gives a ground state to ground state branch of 87.5 % ± 3%. These new data induce a dramatic change in recent summation calculations where a 51% GS to GS branch was considered for ⁹²Rb, increasing the summation antineutrino spectrum in the region nearby the observed bias.The new data still have an important impact on other summation calculations in which more recent data were considered

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

    PubMed

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

    2009-01-01

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

  10. On recording the true absorption spectrum and the scattering spectrum of a turbid sample: application to cell suspensions of the cyanobacterium Anabaena variabilis.

    PubMed

    Merzlyak, M N; Naqvi, K R

    2000-11-01

    An integrating sphere is often used for recording the absorption spectrum of a turbid sample. If the sample is placed inside the sphere, scattering losses are eliminated, but the recorded spectrum suffers from other distortions. These distortions can be avoided by positioning the sample outside the sphere; but, since some of the scattered light escapes the detector, the recorded spectrum suffers from residual scattering losses. A method proposed by Latimer and Eubanks more than 30 years ago (Arch. Biochem. Biophys. 98 (1962) 274), is put to a quantitative examination, which has shown that one can obtain, by recording two spectra at different distances from the sphere, not only the true absorption spectrum but also the scattering spectra of the sample. Conditions for the validity of the basic assumption underlying the method are investigated by examining suspensions containing various concentrations of cells of the cyanobacterium Anabaena variabilis, and it is shown that the calculated absorbance is proportional to the number density of the cells. The application of the method for quantitative spectrophotometric analysis of pigments in cell suspensions is discussed.

  11. CFCl3 (CFC-11): UV Absorption Spectrum Temperature Dependence Measurements and the Impact on Atmospheric Lifetime Uncertainty

    NASA Astrophysics Data System (ADS)

    McGillen, M.; Fleming, E. L.; Jackman, C. H.; Burkholder, J. B.

    2013-12-01

    CFCl3 (CFC-11) is both a major ozone-depleting substance and a potent greenhouse gas that is removed primarily via stratospheric UV photolysis. Uncertainty in the temperature dependence of its UV absorption spectrum is a significant contributing factor to the overall uncertainty in its global lifetime and, thus, model calculations of stratospheric ozone recovery and climate change. In this work, the CFC-11 UV absorption spectrum was measured over a range of wavelength (184.95-230 nm) and temperature (216-296 K). We report a spectrum temperature dependence that is less than currently recommended for use in atmospheric models. The impact on its atmospheric lifetime was quantified using the NASA Goddard Space Flight Center 2-D coupled chemistry-radiation-dynamics model and the spectrum parameterization developed in this work. The modeled global annually averaged lifetime was 58.1 × 0.7 years (2σ uncertainty due solely to the spectrum uncertainty). The lifetime is slightly reduced and the uncertainty significantly reduced from that obtained using current UV spectrum recommendations. CFCl 3 (CFC-11) 2-D model results: Left: Global annually averaged loss rate coefficient (local lifetime) and photolysis and reaction contributions (see legend). Middle: Molecular loss rate and uncertainty limits; the slow and fast profiles were calculated using the 2σ uncertainty estimates in the CFC-11 UV absorption spectrum from this work. Right: CFC-11 concentration profile. CFC-11 loss process contribution to the overall local lifetime uncertainty (2σ) calculated using the 2-D model (see text). Left: Results obtained from this work. Right: Results obtained using model input from Sander et al. [2011] and updates in SPARC [2013].

  12. Effects of color centers absorption on the spectrum of the temperature-dependent radiation-induced attenuation in fiber.

    PubMed

    Jin, Jing; Hou, Yunxia; Liu, Chunjing

    2015-02-01

    Spectra ranging from 800 to 1650 nm of the temperature-dependent radiation-induced attenuation (RIA) in the irradiated and sufficiently annealed fiber with germanium and phosphorous dopant has been measured. These RIA spectra were investigated based on the mechanism of color centers absorption. With the configurational coordinate model, these RIA spectra were decomposed by the absorption bands of three kinds of color centers. The effects of color centers absorption on the spectrum of temperature-dependent RIA is discussed by comparing the absorption intensity of different color centers at a same wavelength. Moreover, the temperature-dependent RIA of the fiber has been measured separately at 850, 1310, and 1550 nm. The measured results agreed well with the analysis of RIA spectra.

  13. The Hubble Space Telescope Quasar Absorption Line Key Project: The Unusual Absorption-Line System in the Spectrum of PG 2302+029--Ejected or Intervening?

    NASA Technical Reports Server (NTRS)

    Jannuzi, B. T.; Hartig, G. F.; Kirhakos, S.; Sargent, W. L. W.; Turnshek, D. A.; Weymann, R. J.; Bahcall, J. N.; Bergeron, J.; Boksenberg, A.; Savage, B. D.; Schneider, D. P.; Wolfe, A. M.

    1996-01-01

    We report the discovery of a high-ionization broad absorption line system at a redshift of z(sub abs) = 0.695 in the spectrum of the z(sub em) = 1.052 radio-quiet quasar PG 2302+029. Broad absorption with FWHM from 3000 to 5000 km/s is detected from C iv, N v, and O vi in Hubble Space Telescope (HST) Faint Object Spectrograph spectra of the quasar. A narrow-line system (FWHM approx. 250 km/s) at z(sub abs) = 0.7016 is resolved from the broad blend and includes absorption by Ly alpha and the C iv, N v, and O vi doublets. No absorption by low-ionization metal species (e.g., Si II and Mg II) is detected in the HST or ground-based spectra for either the broad or the narrow system. The centroids of the broad system lines are displaced by approx. 56,000 km/s to the blue of the quasar's broad emission lines. The reddest extent of the broad-line absorption is more than 50,000 km/s from the quasar. The properties of this system are unprecedented, whether it is an intervening or an ejected system.

  14. The Q(y) absorption spectrum of the light-harvesting complex II as determined by structure-based analysis of chlorophyll macrocycle deformations.

    PubMed

    Zucchelli, Giuseppe; Santabarbara, Stefano; Jennings, Robert C

    2012-04-01

    The absorption spectrum of the main antenna complex of photosystem II, LHCII, has been modeled using, as starting points, the chlorophyll (chl) atomic coordinates as obtained by the LHCII crystal analysis [Liu, Z., Yan, H., Wang, K., Kuang, T., Zhang, J., Gui, L., An, X., and Chang, W. (2004) Nature 428, 287-292] of three different trimers. The chl site Q(y) transition energies have been obtained in terms of the chl macrocycle deformations influencing the energy level of the chl frontier orbitals. Using these chl site transition energy values and the entire set of interaction energies, calculated in the ideal dipole approximation, the complete Hamiltonians for the three LHCII trimers have been written and the full set of 42 eigenstates of each LHCII trimer have been calculated. With the 42 transition energies and transition dipole strengths, either unperturbed or associated to the eigenstates, the LHCII Q(y) absorption spectrum has been calculated using a chl absorption band shape. These calculations have been performed both in vacuo and in the presence of a medium. Despite the number of approximations, a good correlation with the measured absorption spectrum of a LHCII preparation is obtained. This analysis shows that, although a substantial C3 symmetry of the LHCII trimer in terms of both chl-chl distances and interaction energies is present, a marked variation among monomer subsets of site transition energies is estimated. This leads to a C3 symmetry breaking in the unperturbed chl site transition energies set and, consequently, in the trimer eigenstates. It is also concluded that interactions among chlorophylls do not significantly modify the light absorption role of LHCII in plant leaves.

  15. Intracavity Multi-Photon-Absorption and the Quantum Noise Spectrum of Light

    NASA Astrophysics Data System (ADS)

    Herzog, Ulrike

    The intensity noise spectrum is investigated quantum-mechanically for incident coherent light passing through a resonator which is filled with a k-photon-absorber. For k 2 the noise of the outgoing light is reduced below the shot noise level the reduction being maximal for frequencies that are small in comparison to the cavity bandwidth. It turns out that the highest possible value of this low-frequency noise reduction is obtained when the resonator losses due to transmission through the outcoupling mirror are 2k - 1 times as large as the k-photon absorption losses. In this case the noise at zero frequency is reduced with respect to the shot noise level by a factor of k/(2k - 1).Translated AbstractQuantenrauschen bei Mehrphotonenabsorption im ResonatorFür kohärent eingestrahltes Licht, das einen mit einem k-Photon-Absorber gefüllten Resonator durchläuft, wird das Intensitäts-Rauschspektrum quantenmechanisch unter-sucht. Für k 2 liegt das Rauschen des austretenden Lichtes unterhalb des Schrotrauschens, wobei die Rauschreduktion für Frequenzen, die klein im Vergleich zur Resonatorbandbreite sind, am größten ist. Es stellt sich heraus, daß diese niederfrequente Rauschunterdrückung ihren höchsten Wert erreicht, wenn die Resonatorverluste, die infolge der Transmission durch den Auskoppelspiegel entstehen, 2k - 1 mal so groß sind wie die k-Photonen-Absorptionsverluste. In diesem Fall reduziert sich das Rauschen bei der Frequenz Null im Vergleich zum Schrotrauschen um den Faktor k/2k - 1.

  16. Communication: Does a single CH3CN molecule attached to Ru(bipy)3(2+) affect its absorption spectrum?

    PubMed

    Stockett, M H; Brøndsted Nielsen, S

    2015-05-01

    Tris(bipyridine)ruthenium(II) (Ru(bipy)3 (2+)) is a prototypical transition metal coordination complex whose photophysical properties have attracted considerable attention. A much debated issue is whether the metal-to-ligand charge transfer (MLCT) transition that accounts for the complex's beautiful red color is fully delocalized across all three bipyridine ligands or located on just one ligand. Here, we show based on gas-phase action spectroscopy that attachment of a single acetonitrile molecule does not change the absorption spectrum from that of the bare ions, which is indicative of a delocalized state. However, the gas-phase spectra of the bare and one solvent molecule complexes are significantly blueshifted relative to that obtained in bulk acetonitrile, which suggests that in solution the polarizability of many solvent molecules working together can localize the MLCT state. Our data clearly show that more than one solvent molecule is needed to break the symmetry of the MLCT excited state and reproduce its solution-phase characteristics. PMID:25956080

  17. Communication: Does a single CH3CN molecule attached to Ru(bipy)32+ affect its absorption spectrum?

    NASA Astrophysics Data System (ADS)

    Stockett, M. H.; Brøndsted Nielsen, S.

    2015-05-01

    Tris(bipyridine)ruthenium(II) (Ru(bipy)32+) is a prototypical transition metal coordination complex whose photophysical properties have attracted considerable attention. A much debated issue is whether the metal-to-ligand charge transfer (MLCT) transition that accounts for the complex's beautiful red color is fully delocalized across all three bipyridine ligands or located on just one ligand. Here, we show based on gas-phase action spectroscopy that attachment of a single acetonitrile molecule does not change the absorption spectrum from that of the bare ions, which is indicative of a delocalized state. However, the gas-phase spectra of the bare and one solvent molecule complexes are significantly blueshifted relative to that obtained in bulk acetonitrile, which suggests that in solution the polarizability of many solvent molecules working together can localize the MLCT state. Our data clearly show that more than one solvent molecule is needed to break the symmetry of the MLCT excited state and reproduce its solution-phase characteristics.

  18. On the Putative Detection of z > 0 X-Ray Absorption Features in the Spectrum of Mrk 421

    NASA Astrophysics Data System (ADS)

    Rasmussen, Andrew P.; Kahn, Steven M.; Paerels, Frits; Herder, Jan Willem den; Kaastra, Jelle; de Vries, Cor

    2007-02-01

    In a series of papers, Nicastro et al. have reported the detection of z>0 O VII absorption features in the spectrum of Mrk 421 obtained with the Chandra Low Energy Transmission Grating Spectrometer (LETGS). We evaluate this result in the context of a high-quality spectrum of the same source obtained with the Reflection Grating Spectrometer (RGS) on XMM-Newton. The data comprise over 955 ks of usable exposure time and more than 2.6×104 counts per 50 mÅ at 21.6 Å. We concentrate on the spectrally clean region (21.3 <λ<22.5 ), where sharp features due to the astrophysically abundant O VII may reveal an intervening, warm-hot intergalactic medium (WHIM). We do not confirm detection of any of the intervening systems claimed to date. Rather, we detect only three unsurprising, astrophysically expected features down to the log(Ni)~14.6 (3 σ) sensitivity level. Each of the two purported WHIM features is rejected with a statistical confidence that exceeds that reported for its initial detection. While we cannot rule out the existence of fainter, WHIM related features in these spectra, we suggest that previous discovery claims were premature. A more recent paper by Williams et al. claims to have demonstrated that the RGS data we analyze here do not have the resolution or statistical quality required to confirm or deny the LETGS detections. We show that our analysis resolves the issues encountered by Williams et al. and recovers the full resolution and statistical quality of the RGS data. We highlight the differences between our analysis and those published by Williams et al. as this may explain our disparate conclusions.

  19. Hybrid inorganic-organic tandem solar cells for broad absorption of the solar spectrum.

    PubMed

    Speirs, M J; Groeneveld, B G H M; Protesescu, L; Piliego, C; Kovalenko, M V; Loi, M A

    2014-05-01

    We report the first hybrid tandem solar cell with solution processable active layers using colloidal PbS quantum dots (QDs) as the front subcell in combination with a polymer-fullerene rear subcell. Al/WO3 is introduced as an interlayer, yielding an open circuit voltage (VOC) equal to about 92% of the sum of the VOC of the subcells. The device exhibits a power conversion efficiency of 1.8%. Optical simulations of various tandem configurations show that combining PbS QDs with small-bandgap polymers is a promising strategy to obtain tandem solar cells with a very broad absorption range and a high short circuit current. PMID:24652186

  20. Ultraviolet (250-550  nm) absorption spectrum of pure water.

    PubMed

    Mason, John D; Cone, Michael T; Fry, Edward S

    2016-09-01

    Data for the spectral light absorption of pure water from 250 to 550 nm have been obtained using an integrating cavity made from a newly developed diffuse reflector with a very high UV reflectivity. The data provide the first scattering-independent measurements of absorption coefficients in the spectral gap between well-established literature values for the absorption coefficients in the visible (>400  nm) and UV (<200  nm). A minimum in the absorption coefficient has been observed in the UV at 344 nm; the value is 0.000811±0.000227  m-1. PMID:27607297

  1. The origin of blueshifted absorption features in the X-ray spectrum of PG 1211+143: outflow or disc

    NASA Astrophysics Data System (ADS)

    Gallo, L. C.; Fabian, A. C.

    2013-07-01

    In some radio-quiet active galactic nuclei (AGN), high-energy absorption features in the X-ray spectra have been interpreted as ultrafast outflows (UFOs) - highly ionized material (e.g. Fe XXV and Fe XXVI) ejected at mildly relativistic velocities. In some cases, these outflows can carry energy in excess of the binding energy of the host galaxy. Needless to say, these features demand our attention as they are strong signatures of AGN feedback and will influence galaxy evolution. For the same reason, alternative models need to be discussed and refuted or confirmed. Gallo and Fabian proposed that some of these features could arise from resonance absorption of the reflected spectrum in a layer of ionized material located above and corotating with the accretion disc. Therefore, the absorbing medium would be subjected to similar blurring effects as seen in the disc. A priori, the existence of such plasma above the disc is as plausible as a fast wind. In this work, we highlight the ambiguity by demonstrating that the absorption model can describe the ˜7.6 keV absorption feature (and possibly other features) in the quasar PG 1211+143, an AGN that is often described as a classic example of a UFO. In this model, the 2-10 keV spectrum would be largely reflection dominated (as opposed to power law dominated in the wind models) and the resonance absorption would be originating in a layer between about 6 and 60 gravitational radii. The studies of such features constitute a cornerstone for future X-ray observatories like Astro-H and Athena+. Should our model prove correct, or at least important in some cases, then absorption will provide another diagnostic tool with which to probe the inner accretion flow with future missions.

  2. Side-emitting GaAs/AlGaAs SQW LEDs showing wide spectrum using shadow masked growth

    NASA Astrophysics Data System (ADS)

    Vermeire, G.; Buydens, L.; van Daele, P.; Demeester, P.

    1992-05-01

    Side-emitting LEDs are proposed showing a wide optical spectrum. The LEDs were fabricated using a special growth technique called shadow-masked growth (SMG). The width of the window in the shadow mask was gradually changed along the LED stripe direction and therefore resulted in a continuous variation of the layer thickness. The combination with a quantum well active region results in a continuous variation in bandgap and emission wavelength. These different spectra add up at one side of the LED offering a broad spectrum. By decreasing the width of the window, starting from 100 microns, GaAs/AlGaAs GRINSCH SQW LEDs have been realized with spectral widths up to 63 nm and very small spectral ripple.

  3. [Measurements of IR absorption across section and spectrum simulation of lewisite].

    PubMed

    Zhang, Yuan-peng; Wang, Hai-tao; Zhang, Lin; Yang, Liu; Guo, Xiao-di; Bai, Yun; Sun, Hao

    2015-02-01

    The vapor infrared transmission spectra of varied concentration of lewisite-1 were measured by a long-path FT-IR spectrometer, and its characteristic frequencies are 814, 930, 1563 cm(-1); their infrared absorption cross section (a) were determined using Beer-Lambert law. The corresponding sigma values are 3.89 +/- 0.01, 1.43 +/- 0.06, 4.47 +/- 0.05 ( X 10(-20) cm2 x molecule(-1)). Two little teeny peaks, 1158, 1288 cm(-1) were found in the measured spectra. Density Functional Theory (DFT) was applied to calculated the infrared spectra of lewisite-1, -2, -3 on a b3lyp/6-311+g(d, p) level by Gauss09 package. The vibration modes were assigned by Gaussview5. 08. The calculated spectra and experimental spectra are in good agreement with each other in 600-1600 cm(-1) range, for the Person's r is 0.9991. The calculated spectra also showed three characteristic frequencies (293, 360, 374 cm(-1)) related to As atom. 0.977 was a scaling factor we determined for lewisite-1 through least-square error and its performance to scale lewisite-1, -2, -3 was acceptable. The results of this work are useful for monitoring environmental atmospheric concentrations of lewisite. PMID:25970914

  4. Theory of the electronic states and absorption spectrum of the LiCl:Ag+ impurity system

    NASA Astrophysics Data System (ADS)

    Jackson, Koblar A.; Lin, Chun C.

    1990-01-01

    The impurity absorption spectra of Ag+ and Cu+ impurities in alkali halide hosts show characteristically different features, despite the similar nature of the corresponding free ions. We use the self-interaction-corrected local-spin-density (SIC-LSD) theory to calculate the electronic structure of the ground state (4d) and the 5s and 5p excited states of the LiCl:Ag+ impurity ion. The method of linear combinations of atomic orbitals is used to determine the wave functions and energy levels. By comparing with previous calculations for LiCl:Cu+, we are able to attribute the differences in the d-->s and d-->p transitions in the ultraviolet spectra of these systems to the increased bonding between host crystal and impurity orbitals in LiCl:Ag+, due to the more extensive nature of the Ag+ 4d orbitals. A modification of the earlier SIC-LSD impurity-crystal procedure is introduced to treat the strongly mixed impurity states.

  5. Investigation of the ammonia absorption band near 6450 A in the spectrum of Saturn. I - Observations

    NASA Astrophysics Data System (ADS)

    Avramchuk, V. V.; Karmeliuk, A. I.

    Forty-three lines in the vibrational-rotational absorption band of ammonia near 6450 A were found in coudespectrograms of Saturn obtained with the 2-m telescope of the Shemakha Astrophysical Observatory during 1969-1971. Equivalent widths and half-widths were determined and the J and K quantum numbers were defined for some of these lines. The intensity of the integral absorption of the ammonia band was also measured.

  6. The absorption spectrum of the QSO PKS 2126-158 (z_em =3.27) at high resolution

    NASA Astrophysics Data System (ADS)

    D'Odorico, V.; Cristiani, S.; D'Odorico, S.; Fontana, A.; Giallongo, E.

    1998-01-01

    Spectra of the z_em = 3.268 quasar PKS 2126-158 have been obtained in the range lambda lambda 4300-6620 Angstroms with a resolution Rsmallimeq27000 and an average signal-to-noise ratio s/nsmallimeq 25 per resolution element. The list of the identified absorption lines is given together with their fitted column densities and Doppler widths. The modal value of the Doppler parameter distribution for the Lyalpha lines is smallimeq 25 km s(-1) . The column density distribution can be described by a power-law dn / dN ~ N(-beta ) with beta smallimeq 1.5. 12 metal systems have been identified, two of which were previously unknown. In order to make the column densities of the intervening systems compatible with realistic assumptions about the cloud sizes and the silicon to carbon overabundance, it is necessary to assume a jump beyond the He II edge in the spectrum of the UV ionizing background at z smallim 3 a factor 10 larger than the standard predictions for the integrated quasar contribution. An enlarged sample of C IV absorptions (71 doublets) has been used to analyze the statistical properties of this class of absorbers strictly related to galaxies. The column density distribution is well described by a single power-law, with beta =1.64 and the Doppler parameter distribution shows a modal value b_CIV smallimeq 14 km s(-1) . The two point correlation function has been computed in the velocity space for the individual components of C IV features. A significant signal is obtained for scales smaller than 200- 300 km s(-1) , xi (30< Delta v < 90 km\\ s(-1) ) = 33 +/- 3. A trend of decreasing clustering amplitude with decreasing column density is apparent, analogously to what has been observed for Lyalpha lines. Based on observations collected at the European Southern Observatory, La Silla, Chile (ESO No. 2-013-49K). Table 2 is only available in electronic from via anonymous ftp 130.79.128.5 or http://cdsweb.u-strasbg.fr/Abstract.html

  7. Quantum Monte Carlo for the x-ray absorption spectrum of pyrrole at the nitrogen K-edge

    SciTech Connect

    Zubarev, Dmitry Yu.; Austin, Brian M.; Lester, William A. Jr.

    2012-04-14

    Fixed-node diffusion Monte Carlo (FNDMC) is used to simulate the x-ray absorption spectrum of a gas-phase pyrrole molecule at the nitrogen K-edge. Trial wave functions for core-excited states are constructed from ground-state Kohn-Sham determinants substituted with singly occupied natural orbitals from configuration interaction with single excitations calculations of the five lowest valence-excited triplet states. The FNDMC ionization potential (IP) is found to lie within 0.3 eV of the experimental value of 406.1 {+-} 0.1 eV. The transition energies to anti-bonding virtual orbitals match the experimental spectrum after alignment of IP values and agree with the existing assignments.

  8. A photon counting and a squeezing measurement method by the exact absorption and dispersion spectrum of Λ-type Atoms.

    PubMed

    Naeimi, Ghasem; Alipour, Samira; Khademi, Siamak

    2016-01-01

    Recently, the master equations for the interaction of two-mode photons with a three-level Λ-type atom are exactly solved for the coherence terms. In this paper the exact absorption spectrum is applied for the presentation of a non-demolition photon counting method, for a few number of coupling photons, and its benefits are discussed. The exact scheme is also applied where the coupling photons are squeezed and the photon counting method is also developed for the measurement of the squeezing parameter of the coupling photons. PMID:27610321

  9. Molecular level all-optical logic with chlorophyll absorption spectrum and polarization sensitivity

    NASA Astrophysics Data System (ADS)

    Raychaudhuri, B.; Bhattacharyya (Bhaumik), S.

    2008-06-01

    Chlorophyll is suggested as a suitable medium for realizing optical Boolean logic at the molecular level in view of its wavelength-selective property and polarization sensitivity in the visible region. Spectrophotometric studies are made with solutions of total chlorophyll and chromatographically isolated components, viz. chlorophyll a and b and carotenoids extracted from pumpkin leaves of different maturity stages. The absorption features of matured chlorophyll with two characteristic absorption peaks and one transmission band are molecular properties and independent of concentration. A qualitative explanation of such an absorption property is presented in terms of a ‘particle in a box’ model and the property is employed to simulate two-input optical logic operations. If both of the inputs are either red or blue, absorption is high. If either one is absent and replaced by a wavelength of the transmission band, e.g. green, absorption is low. Assigning these values as 0 s or 1 s, AND and OR operations can be performed. A NOT operation can be simulated with the transmittance instead of the absorbance. Also, the shift in absorbance values for two different polarizations of the same monochromatic light can simulate two logical states with a single wavelength. Cyclic change in absorbance is noted over a rotation of 360° for both red and blue peaks, although the difference is not very large. Red monochromatic light with polarizations apart by 90°, corresponding to maximum and minimum absorption, respectively, may be assigned as the two logical states. The fluorescence emissions for different pigment components are measured at different excitation wavelengths and the effect of fluorescence on the red absorbance is concluded to be negligible.

  10. FUSE Observations of Galactic and Intrinsic Absorption in the Spectrum of the Seyfert 1 Galaxy 2MASX J21362313-6224008

    NASA Technical Reports Server (NTRS)

    Bonamente, Massimiliano; Dixon, W. Van Dyke

    2004-01-01

    We present the far-ultraviolet spectrum of the Seyfert 1 galaxy 2MASX J21362313-6224008 obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE). The spectrum features absorption from Galactic O VI at two velocities and redshifted H I Ly beta and gamma, C II, CIII, and O VI. The redshifted absorption features represent a single kinematic component blueshifted by approx. 310 km/s relative to the active galactic nucleus. We use photoionization models to derive constraints on the physical parameters of the absorbing gas. An alternative interpretation for the absorption lines is also proposed, wherein the absorbing gas is associated with an intervening galaxy cluster.

  11. FUSE Detection of Galactic and Intrinsic Absorption in the Spectrum of the Seyfert 1 Galaxy 2MASX J21362313-6224008

    NASA Technical Reports Server (NTRS)

    Bonamente, Massimiliano; VanDykeDixon, W.

    2003-01-01

    We present the far-ultraviolet spectrum of the Seyfert 1 galaxy 2MASX 521362313-6224008 obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE). The spectrum features absorption from Galactic O VI at two velocities and redshifted H I Lyman beta and gamma, C II, C III, and O VI. The redshifted absorption features represent a single kinematic component blueshifted by approx. 310 km/s relative to the AGN. We use photoionization models to derive the physical parameters of the absorbing gas. An alternative interpretation for the absorption lines is also proposed, whereby the absorbing gas is associated with an intervening galaxy cluster.

  12. Synthesis and two-photon absorption spectrum of fluorenone-based molecules

    NASA Astrophysics Data System (ADS)

    Dipold, J.; Batista, R. J. M. B.; Fonseca, R. D.; Silva, D. L.; Moura, G. L. C.; dos Anjos, J. V.; Simas, A. M.; De Boni, L.; Mendonca, C. R.

    2016-09-01

    The two-photon absorption (2PA) of five symmetrical fluorenone-based molecules is studied by femtosecond wavelength-tunable Z-scan, as well as quantum-chemical calculations. The molecules are transparent for wavelengths greater than 500 nm and two main one-photon absorption bands are observed in the blue region; one weak, centered at 450 nm, and a stronger one at approximately 360 nm. We observed a strong 2PA band located around 720 nm with maxima 2PA cross-sections between 100 and 230 GM. Quantum chemical calculations employing the response function formalism were performed at the Density Function Theory level to support the interpretation of the experimental nonlinear spectra.

  13. High-resolution, vacuum-ultraviolet absorption spectrum of boron trifluoride

    SciTech Connect

    Hughes, Patrick P.; Thompson, Alan K.; Vest, Robert E.; Sprague, Matthew K.; Irikura, Karl K.; Beasten, Amy; McComb, Jacob C.; Al-Sheikhly, Mohamad; Coplan, Michael A.; Clark, Charles W.

    2014-11-21

    In the course of investigations of thermal neutron detection based on mixtures of {sup 10}BF{sub 3} with other gases, knowledge was required of the photoabsorption cross sections of {sup 10}BF{sub 3} for wavelengths between 135 and 205 nm. Large discrepancies in the values reported in existing literature led to the absolute measurements reported in this communication. The measurements were made at the SURF III Synchrotron Ultraviolet Radiation Facility at the National Institute of Standards and Technology. The measured absorption cross sections vary from 10{sup −20} cm{sup 2} at 135 nm to less than 10{sup −21} cm{sup 2} in the region from 165 to 205 nm. Three previously unreported absorption features with resolvable structure were found in the regions 135–145 nm, 150–165 nm, and 190–205 nm. Quantum mechanical calculations, using the TD-B3LYP/aug-cc-pVDZ variant of time-dependent density functional theory implemented in Gaussian 09, suggest that the observed absorption features arise from symmetry-changing adiabatic transitions.

  14. Visible-band (390-940nm) monitoring of the Pluto absorption spectrum during the New Horizons encounter

    NASA Astrophysics Data System (ADS)

    Smith, Robert J.; Marchant, Jonathan M.

    2015-11-01

    Whilst Earth-based observations obviously cannot compete with New Horizons’ on-board instrumentation in most regards, the New Horizons data set is essentially a snapshot of Pluto in July 2015. The New Horizons project team therefore coordinated a broad international observing campaign to provide temporal context and to take advantage of the once-in-a-lifetime opportunity to directly link our Earth-based view of Pluto with “ground truth” provided by in situ measurements. This both adds value to existing archival data sets and forms the basis of long term, monitoring as we watch Pluto recede from the Sun over the coming years. We present visible-band (390-940nm) monitoring of the Pluto absorption spectrum over the period July - October 2015 from the Liverpool Telescope (LT). In particular we wished to understand the well-known 6-day fluctuation in the methane ice absorption spectrum which is observable from Earth in relation to the never-before-available high resolution maps of the Pluto surface. The LT is a fully robotic 2.0m optical telescope that automatically and dynamically schedules observations across 30+ observing programmes with a broad instrument suite. It is ideal for both reactive response to dynamic events (such as the fly-by) and long term, stable monitoring with timing constraints individually optimised to the science requirements of each programme. For example past studies of the observed CH4 absorption variability have yielded ambiguity of whether they were caused by real physical changes or geometric observation constraints, in large part because of the uneven time sampling imposed by traditional telescope scheduling.

  15. Absorption spectrum of neat liquid benzene and its concentrated solutions in n-hexane from 220 to 170 nm

    SciTech Connect

    Saik, V.O.; Lipsky, S.

    1995-03-30

    The electronic absorption spectrum of benzene has been obtained by phototransmission measurements over a concentration range from 0.005 M in n-hexane to the neat liquid at 11.2 M and over a spectral range that extends down to 170 nm. Good agreement is obtained with previously reported measurements on the neat liquid. The oscillator strength of the strongly allowed A{sub 1g} {yields} E{sub 1u} transition is maintained at ca. 1.0 as the benzene concentration increases but is accompanied by extensive redistribution of the intensity such that the optical cross section at the position of the absorption maximum (which shifts from 184{sub .2} nm in dilute solution to 189{sub .5} nm in the neat liquid) reduces by a factor of 2.7. An explanation for these changes in terms of Lorentz field corrections to the complex dielectric constant is developed, and its implication to the assignment of the neat liquid absorption as a collective excitation is considered. 43 refs., 5 figs., 1 tab.

  16. Analysis of the Contribution of Chromophores in Side Groups of Amino Acids to the Absorption Spectrum of Hemoglobin

    NASA Astrophysics Data System (ADS)

    Lavrinenko, I. A.; Vashanov, G. A.; Ruban, M. K.

    2014-01-01

    Based on spectral analysis of solutions of aromatic, heterocyclic, and sulfur-containing amino acids, we propose an additive model and assess the roles of the studied types of amino acid residues in formation of the overall absorption spectrum of hemoglobin. We have established that the identified absorption maxima (transitions) at 243.4, 248.4, 253.2, 258.8, 261.6, 264.8, and 268.4 nm belong to phenylalanine amino acid residues. Probably the latter also form the unassigned transition at 241.0 nm. The transitions at 272.8, 274.6, 280.0, and 284.4 nm are a superposition of the absorption by the side groups of tyrosine and tryptophan; the transition at 278.2 nm is associated with tyrosine, masked by adjacent transitions of tryptophan, and the transition at 291.2 nm belongs to tryptophan. We consider the possibility of estimating the changes in the spectral properties of proteins under the influence of various physical and chemical factors using data from additive spectra.

  17. The effect of surface irradiance on the absorption spectrum of chromophoric dissolved organic matter in the global ocean

    NASA Astrophysics Data System (ADS)

    Swan, Chantal M.; Nelson, Norman B.; Siegel, David A.; Kostadinov, Tihomir S.

    2012-05-01

    The cycling pathways of chromophoric dissolved organic matter (CDOM) within marine systems must be constrained to better assess the impact of CDOM on surface ocean photochemistry and remote sensing of ocean color. Photobleaching, the loss of absorption by CDOM due to light exposure, is the primary sink for marine CDOM. Herein the susceptibility of CDOM to photobleaching by sea surface-level solar radiation was examined in 15 samples collected from wide-ranging open ocean regimes. Samples from the Pacific, Atlantic, Indian and Southern Oceans were irradiated over several days with full-spectrum light under a solar simulator at in situ temperature in order to measure photobleaching rate and derive an empirical matrix, ɛsurf (m-1 μEin-1), which quantifies the effect of surface irradiance on the spectral absorption of CDOM. Irradiation responses among the ocean samples were similar within the ultraviolet (UV) region of the spectrum spanning 300-360 nm, generally exhibiting a decrease in the CDOM absorption coefficient (m-1) and concomitant increase in the CDOM spectral slope parameter, S (nm-1). However, an unexpected irradiation-induced increase in CDOM absorption between approximately 360 and 500 nm was observed for samples from high-nutrient low-chlorophyll (HNLC) environments. This finding was linked to the presence of dissolved nitrate and may explain discrepancies in action spectra for dimethylsulfide (DMS) photobleaching observed between the Equatorial Pacific and Subtropical North Atlantic Oceans. The nitrate-to-phosphate ratio explained 27-70% of observed variability in ɛsurf at observation wavelengths of 330-440 nm, while the initial spectral slope of the samples explained up to 52% of variability in ɛsurf at observation wavelengths of 310-330 nm. These results suggest that the biogeochemical and solar exposure history of the water column, each of which influence the chemical character and thus the spectral quality of CDOM and its photoreactivity, are the

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

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

  19. Detection of a deep 3-microm absorption feature in the spectrum of Amalthea (JV).

    PubMed

    Takato, Naruhisa; Bus, Schelte J; Terada, Hiroshi; Pyo, Tae-Soo; Kobayashi, Naoto

    2004-12-24

    Near-infrared spectra of Jupiter's small inner satellites Amalthea and Thebe are similar to those of D-type asteroids in the 0.8- to 2.5-micrometer wavelength range. A deep absorption feature is detected at 3 micrometers in the spectra of the trailing side of Amalthea, which is similar to that of the non-ice components of Callisto and can be attributed to hydrous minerals. These surface materials cannot be explained if the satellite formed at its present orbit by accreting from a circumjovian nebula. Amalthea and Thebe may be the remnants of Jupiter's inflowing building blocks that formed in the outer part or outside of the circumjovian nebula.

  20. Detection of a Deep 3-μm Absorption Feature in the Spectrum of Amalthea (JV)

    NASA Astrophysics Data System (ADS)

    Takato, Naruhisa; Bus, Schelte J.; Terada, Hiroshi; Pyo, Tae-Soo; Kobayashi, Naoto

    2004-12-01

    Near-infrared spectra of Jupiter's small inner satellites Amalthea and Thebe are similar to those of D-type asteroids in the 0.8- to 2.5-micrometer wavelength range. A deep absorption feature is detected at 3 micrometers in the spectra of the trailing side of Amalthea, which is similar to that of the non-ice components of Callisto and can be attributed to hydrous minerals. These surface materials cannot be explained if the satellite formed at its present orbit by accreting from a circumjovian nebula. Amalthea and Thebe may be the remnants of Jupiter's inflowing building blocks that formed in the outer part or outside of the circumjovian nebula.

  1. Detection of a deep 3-microm absorption feature in the spectrum of Amalthea (JV).

    PubMed

    Takato, Naruhisa; Bus, Schelte J; Terada, Hiroshi; Pyo, Tae-Soo; Kobayashi, Naoto

    2004-12-24

    Near-infrared spectra of Jupiter's small inner satellites Amalthea and Thebe are similar to those of D-type asteroids in the 0.8- to 2.5-micrometer wavelength range. A deep absorption feature is detected at 3 micrometers in the spectra of the trailing side of Amalthea, which is similar to that of the non-ice components of Callisto and can be attributed to hydrous minerals. These surface materials cannot be explained if the satellite formed at its present orbit by accreting from a circumjovian nebula. Amalthea and Thebe may be the remnants of Jupiter's inflowing building blocks that formed in the outer part or outside of the circumjovian nebula. PMID:15618511

  2. Aerosol absorption retrievals from the PACE broad spectrum Ocean Color Instrument (OCI)

    NASA Astrophysics Data System (ADS)

    Mattoo, S.; Remer, L. A.; Levy, R. C.; Torres, O.; Gupta, P.; Ahmad, Z.

    2015-12-01

    The PACE (Pre- Aerosol, Clouds and ocean Ecosystem) mission, anticipated for launch in the early 2020s is designed to characterize oceanic and atmospheric properties. The primary instrument on-board will be a moderate resolution (~1 km nadir) radiometer, called the Ocean Color Instrument (OCI). OCI's main purpose will be to enhance current science in aquatic biogeochemistry by offering greater capability than either MODIS or SeaWiFS. To do so, OCI will provide high spectral resolution (5 nm) from the UV to NIR (350 - 800 nm), with additional spectral bands in the NIR and SWIR to support atmospheric correction. Supplementary instruments, such as a multi-angle imaging polarimeter are also being discussed, and these supplementary instruments are associated with the atmospheric objectives of the mission, although they may also offer important new measurements for oceanic objectives. However, the OCI itself is an excellent instrument for atmospheric objectives, providing measurements across a broad spectral range that in essence combines the capabilities of MODIS and OMI, but with the UV channels from OMI to be available at moderate resolution. In preparation for the PACE mission we have begun the theoretical work necessary to create a robust, operational aerosol retrieval for OCI. This retrieval is based on the MODIS Dark Target aerosol retrieval over ocean that returns aerosol optical depth and an estimate of aerosol size distribution. It then uses these retrieved parameters to constrain a retrieval of aerosol absorption in the UV, using the OCI UV channels. The algorithm is described and its sensitivity to retrieval assumptions is tested. The goal is to understand the limitations of such an algorithm and under what conditions could we expect to obtain quantitative aerosol absorption information from OCI on PACE.

  3. Vibrational structure of n-π* transition of the UV absorption spectrum of acryloyl fluoride in the gas phase.

    PubMed

    Koroleva, Lidiya A; Tyulin, Vladimir I; Matveev, Vladimir K; Pentin, Yuriy A

    2014-03-25

    UV absorption spectrum of acryloyl fluoride molecule in the gas phase has been obtained in the region at 32600-35500 cm(-1) with the purpose of the investigation of the hindered internal rotation. The resolved vibrational structure of this spectrum consists of 92 absorption bands, each of which corresponds to a certain transition from the ground (S0) to excited (S1) electronic state. The assignment of all bands has been made. The values ν00trans=34831.8 cm(-1) and ν00cis=34679.2 cm(-1) have been determined. Several Deslandres Tables (DTs) have been constructed for torsional vibration of s-trans- and s-cis-isomers of investigated molecule. The origins in these DTs correspond to bands assigned to ν00 and to fundamental frequencies of each isomer in the S0 and S1 states. These DTs have been used to determine the harmonic frequencies ωe, anharmonicity coefficients x11, and frequencies of the torsional vibration transitions (0-υ) up to high values of the vibrational quantum number υ of s-trans- and s-cis-isomers in the both electronic states. The frequencies of torsional vibrations are ν1(″)=116.5cm(-1) for s-trans-isomer and ν1(″)=101.2 cm(-1) for s-cis-isomer in the S0 state. The frequencies of ones are ν1(')=170.4 cm(-1) for s-trans-isomer and ν1(')=139.7 cm(-1) for s-cis-isomer in the S1 state. The fundamental vibrational frequencies set has been found for isomers in the S0 and S1 states.

  4. Substituent and solvent effects on the UV-vis absorption spectrum of the photoactive yellow protein chromophore.

    PubMed

    García-Prieto, F Fernández; Aguilar, M A; Galván, I Fdez; Muñoz-Losa, A; Olivares del Valle, F J; Sánchez, M L; Martín, M E

    2015-05-28

    Solvent effects on the UV-vis absorption spectra and molecular properties of four models of the photoactive yellow protein (PYP) chromophore have been studied with ASEP/MD, a sequential quantum mechanics/molecular mechanics method. The anionic trans-p-coumaric acid (pCA(-)), thioacid (pCTA(-)), methyl ester (pCMe(-)), and methyl thioester (pCTMe(-)) derivatives have been studied in gas phase and in water solution. We analyze the modifications introduced by the substitution of sulfur by oxygen atoms and hydrogen by methyl in the coumaryl tail. We have found some differences in the absorption spectra of oxy and thio derivatives that could shed light on the different photoisomerization paths followed by these compounds. In solution, the spectrum substantially changes with respect to that obtained in the gas phase. The n → π1* state is destabilized by a polar solvent like water, and it becomes the third excited state in solution displaying an important blue shift. Now, the π → π1* and π → π2* states mix, and we find contributions from both transitions in S1 and S2. The presence of the sulfur atom modulates the solvent effect and the first two excited states become practically degenerate for pCA(-) and pCMe(-) but moderately well-separated for pCTA(-) and pCTMe(-).

  5. Highly Ionized Iron Absorption Lines from Outflowing Gases in the X-ray Spectrum of NGC 1365

    NASA Technical Reports Server (NTRS)

    Risaliti, G.; Bianchi, S.; Matt, G.; Baldi, A.; Elvis, M.; Fabbiano, G.; Zezas, A.

    2006-01-01

    We present the discovery of four absorption lines in the X-ray spectrum of the Seyfert galaxy NGC 1365, at energies between 6.7 and 8.3 keV. The lines are detected with high statistical confidence (from >20 sigma for the strongest to -4 sigma for the weakest) in two XMM-Newton observations 60 ks long. We also detect the same lines, with a lower signal-to-noise ratio (but still >2 sigma for each line), in two previous shorter (-10 ks) XMM-Newton observations. The spectral analysis identifies these features as Fe XXV and Fe XXVI Kalpha and Kbeta lines, outflowing with velocities varying between -1000 and -5000 km/s among the observations. These are the highest quality detections of such lines so far. The high equivalent widths [EW (Kalpha) approximately 100 eV] and the Kalpha/Kbeta ratios imply that the lines are due to absorption of the AGN continuum by a highly ionized gas with column density NH-5?1023 cm(exp -2) at a distance of -(50-100)RS from the continuum source.

  6. Time variations of an absorption feature in the spectrum of the gamma-ray burst on 1980 April 19

    NASA Technical Reports Server (NTRS)

    Dennis, B. R.; Frost, K. J.; Kiplinger, A. L.; Orwig, L. E.; Desai, U.; Cline, T. L.

    1982-01-01

    The photon number spectrum integrated over the impulsive part of the event is shown to fit a thermal bremsstrahlung function with a temperature of 330 + or - 70 keV at energies between 151 and 487 keV. At lower energies, the data points lie considerably below this function, indicating a broad absorption feature extending down to values less than or equal to 28 keV, the lowest energy measured. The upper energy of this absorption feature varies from 100 to 150 keV on a time scale less than or equal to 0.5 s. This event is interpreted as a typical gamma ray burst, even though it is still considered remotely possible that it is of solar origin. The spectral features, together with their variability, are interpreted in terms of electron interactions at the cyclotron resonance frequency in magnetic fields of 10 to the 12th - 10 to the 13th gauss close to the surface of a neutron star.

  7. The Fourier transform absorption spectrum of acetylene between 8280 and 8700 cm-1

    NASA Astrophysics Data System (ADS)

    Lyulin, O. M.; Vander Auwera, J.; Campargue, A.

    2016-07-01

    High resolution (0.011 cm-1) room temperature (295 K) Fourier transform absorption spectra (FTS) of acetylene have been analyzed in the 8280-8700 cm-1 range dominated by the ν1+ν2+ν3 band at 8512 cm-1. Line positions and intensities were retrieved from FTS spectra recorded at 3.84 and 56.6 hPa. As a result, a list of 1001 lines was constructed with intensities ranging between about 2×10-26 and 10-22 cm/molecule. Comparison with accurate predictions provided by a global effective operator model led to the assignment of 629 12C2H2 lines. In addition, 114 lines of the 13C12CH2 isotopologue were assigned using information available in the literature. The 12C2H2 lines belong to thirteen bands, nine of which being newly reported. The 13C12CH2 lines belong to three bands, the intensities of which being reported for the first time. Spectroscopic parameters of the 12C2H2 upper vibrational levels were derived from band-by-band analyses of the line positions (typical rms are on the order of 0.002 cm-1). Three of the analyzed bands were found to be affected by rovibrational perturbations, which are discussed in the frame of a global effective Hamiltonian. The obtained line parameters are compared with those of the two bands included in the HITRAN 2012 database.

  8. Optoelectronic set for measuring the absorption spectrum of the thin biological media

    NASA Astrophysics Data System (ADS)

    Gryko, Lukasz; Zajac, Andrzej; Gilewski, Marian

    2013-10-01

    In the paper the authors present the developed optoelectronic system for controlled, repetitive exposure by electromagnetic radiation of biological structures in the Low Level Laser (LED) Therapy procedures. The set allows for objective selection and control of the irradiation parameters by light from spectral range of the tissues transmission window. Measurements of optical parameters of thin biological medium - spectral absorption coefficient and the amount of absorbed energy - can be implemented in the measuring chamber during irradiation treatment. The radiation source is the broadband illuminator consists of set of selected high power LEDs. The maximum optical power of single source is from 80 mW to 800 mW. Illuminator is controlled and powered by the multi-channel prototype control system, which allows independently control a current of each emitter. This control allows shaping spectral emission characteristic of broadband source in range 600-1000 nm. Illuminator allows providing in the working area of 700 cm2 a uniform distribution of optical power density, of 10 mW/cm2 for maximum. Set ensure uniform distribution of the spectral power density of up to 40 mW/nm.

  9. Ab Initio Calculation of the Ultraviolet-Visible (UV-vis) Absorption Spectrum, Electron-Loss Function, and Reflectivity of Solids.

    PubMed

    Ferrari, Anna Maria; Orlando, Roberto; Rérat, Michel

    2015-07-14

    The field frequency has recently been taken into account in the coupled-perturbed Hartree-Fock or Kohn-Sham method implemented in the CRYSTAL code for calculating the high-frequency dielectric constant of semiconductors up to the first electronic transitions. In this work, we document how the code has been generalized and improved in order to compute the full ultraviolet-visible (UV-vis) absorption spectrum, the electron loss function, and the reflectivity from the real and imaginary parts of the electric response property. We show how spectra are modified when the crystalline orbital relaxation due to the dynamic electric field is taken into account, and how this modification increases with the percentage of Hartree-Fock exchange in the unperturbed hybrid Hamiltonian.

  10. A method to obtain the absorption coefficient spectrum of single grain coal in the aliphatic C-H stretching region using infrared transflection microspectroscopy.

    PubMed

    Tonoue, Ryota; Katsura, Makoto; Hamamoto, Mai; Bessho, Hiroki; Nakashima, Satoru

    2014-01-01

    A method was developed to obtain the absorption coefficient spectrum of a grain of coal (as small as 10(-7)) in the region of aliphatic and aromatic C-H stretching bands (2700-3200 cm(-1)) using infrared transflection microspectroscopy. In this method, the complex refractive index n - ik was determined using an optimization algorithm with the Kramers-Kronig transform so that the calculated transflection spectrum from the Fresnel equation corresponded to the measured one. The obtained absorption coefficients were compared with the bulk values determined from the potassium bromide (KBr) pellet measurement method.

  11. The spectral variability of the GHZ-Peaked spectrum radio source PKS 1718-649 and a comparison of absorption models

    SciTech Connect

    Tingay, S. J.; Macquart, J.-P.; Wayth, R. B.; Trott, C. M.; Emrich, D.; Collier, J. D.; Wong, G. F.; Rees, G.; Stevens, J.; Carretti, E.; Callingham, J. R.; Gaensler, B. M.; McKinley, B.; Briggs, F.; Bernardi, G.; Bowman, J. D.; Cappallo, R. J.; Corey, B. E.; Deshpande, A. A.; Goeke, R.; and others

    2015-02-01

    Using the new wideband capabilities of the ATCA, we obtain spectra for PKS 1718-649, a well-known gigahertz-peaked spectrum radio source. The observations, between approximately 1 and 10 GHz over 3 epochs spanning approximately 21 months, reveal variability both above the spectral peak at ∼3 GHz and below the peak. The combination of the low- and high-frequency variability cannot be easily explained using a single absorption mechanism, such as free–free absorption or synchrotron self-absorption. We find that the PKS 1718-649 spectrum and its variability are best explained by variations in the free–free optical depth on our line of sight to the radio source at low frequencies (below the spectral peak) and the adiabatic expansion of the radio source itself at high frequencies (above the spectral peak). The optical depth variations are found to be plausible when X-ray continuum absorption variability seen in samples of active galactic nuclei is considered. We find that the cause of the peaked spectrum in PKS 1718-649 is most likely due to free–free absorption. In agreement with previous studies, we find that the spectrum at each epoch of observation is best fit by a free–free absorption model characterized by a power-law distribution of free–free absorbing clouds. This agreement is extended to frequencies below the 1 GHz lower limit of the ATCA by considering new observations with Parkes at 725 MHz and 199 MHz observations with the newly operational Murchison Widefield Array. These lower frequency observations argue against families of absorption models (both free–free and synchrotron self-absorption) that are based on simple homogenous structures.

  12. Tract-Specific Analyses of Diffusion Tensor Imaging Show Widespread White Matter Compromise in Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Shukla, Dinesh K.; Keehn, Brandon; Muller, Ralph-Axel

    2011-01-01

    Background: Previous diffusion tensor imaging (DTI) studies have shown white matter compromise in children and adults with autism spectrum disorder (ASD), which may relate to reduced connectivity and impaired function of distributed networks. However, tract-specific evidence remains limited in ASD. We applied tract-based spatial statistics (TBSS)…

  13. An Fe XXIV Absorption Line in the Persistent Spectrum of the Dipping Low-Mass X-Ray Binary 1A 1744-361

    NASA Technical Reports Server (NTRS)

    Gavriil, Fotis P.; Strohmayer, Tod E.; Bhattacharyya, Sudip

    2012-01-01

    We report on Chandra X-ray Observatory (Chandra) High Energy Transmission Grating spectra of the dipping low-mass X-ray binary 1A 1744-361 during its 2008 July outburst. We find that its persistent emission is well modeled by a blackbody (kT approx. 1.0 keV) plus power law (Gamma approx. 1.7) with an absorption edge. In the residuals of the combined spectrum, we find a significant absorption line at 6.961 +/- 0.002 keV, consistent with the Fe xxvi (hydrogen-like Fe) 2-1 transition.We place an upper limit on the velocity of a redshifted flow of nu < 221 km/s. We find an equivalent width for the line of 27+2/-3 eV, from which we determine a column density of (7 +/- 1)×10(exp 17) /sq. cm via a curve-of-growth analysis. Using XSTAR simulations, we place a lower limit on the ionization parameter of >103.6 erg cm/s. We discuss what implications the feature has on the system and its geometry. We also present Rossi X-ray Timing Explorer data accumulated during this latest outburst and, via an updated color-color diagram, clearly show that 1A 1744-361 is an "atoll" source

  14. AN Fe XXIV ABSORPTION LINE IN THE PERSISTENT SPECTRUM OF THE DIPPING LOW-MASS X-RAY BINARY 1A 1744-361

    SciTech Connect

    Gavriil, Fotis P.; Strohmayer, Tod E.; Bhattacharyya, Sudip

    2012-07-01

    We report on Chandra X-ray Observatory (Chandra) High Energy Transmission Grating spectra of the dipping low-mass X-ray binary 1A 1744-361 during its 2008 July outburst. We find that its persistent emission is well modeled by a blackbody (kT {approx} 1.0 keV) plus power law ({Gamma} {approx} 1.7) with an absorption edge. In the residuals of the combined spectrum, we find a significant absorption line at 6.961 {+-} 0.002 keV, consistent with the Fe XXVI (hydrogen-like Fe) 2-1 transition. We place an upper limit on the velocity of a redshifted flow of v < 221 km s{sup -1}. We find an equivalent width for the line of 27{sup +2}{sub -3} eV, from which we determine a column density of (7 {+-} 1) Multiplication-Sign 10{sup 17} cm{sup -2} via a curve-of-growth analysis. Using XSTAR simulations, we place a lower limit on the ionization parameter of >10{sup 3.6} erg cm s{sup -1}. We discuss what implications the feature has on the system and its geometry. We also present Rossi X-ray Timing Explorer data accumulated during this latest outburst and, via an updated color-color diagram, clearly show that 1A 1744-361 is an 'atoll' source.

  15. Bayesian Analysis of an Excitonic Absorption Spectrum in a Cu2O Thin Film Sandwiched by Paired MgO Plates

    NASA Astrophysics Data System (ADS)

    Iwamitsu, Kazunori; Aihara, Shingo; Okada, Masato; Akai, Ichiro

    2016-09-01

    We analyzed the absorption spectrum of a Cu2O thin film sandwiched by paired MgO plates with the Metropolis algorithm of Bayesian estimation to estimate the energy shift of a yellow excitonic band gap. In the absorption spectrum, discrete excitonic resonant transitions with homogeneous and inhomogeneous widths are superimposed upon the tail parts of excitonic continuum and band-to-band absorption bands. On the basis of the Metropolis samplings with 2.5 million steps after sufficient burn-in steps, the spectral parameters of the excitonic resonant transitions can be estimated satisfactorily with a high degree of accuracy. In particular, we demonstrated that the yellow excitonic band gap in the Cu2O thin film shifts to the lower energy side than that of Cu2O bulk crystals. This result is consistent with the stress relaxation model for such Cu2O thin films, which was reported in Eur. Phys. J. B 86, 194 (2013).

  16. Accurate calculation of the x-ray absorption spectrum of water via the GW/Bethe-Salpeter equation

    NASA Astrophysics Data System (ADS)

    Gilmore, Keith; Vinson, John; Kas, Josh; Vila, Fernando; Rehr, John

    2014-03-01

    We calculate x-ray absorption spectra (XAS) of water within the OCEAN code, which combines plane-wave, pseudopotential electronic structure, PAW transition elements, GW self-energy corrections, and the NIST BSE solver. Due to the computational demands of this approach, our initial XAS calculations were limited to 17 molecule super cells. This lead to unphysical, size dependent effects in the calculated spectra. To treat larger systems, we extended the OCEAN interface to support well-parallelized codes such as QuantumESPRESSO. We also implemented an efficient interpolation scheme of Shirley. We applied this large-scale GW/BSE approach to 64 molecule unit cell structures of water obtained from classical DFT/MD and PIMD simulations. In concurrence with previous work, we find the calculated spectrum both qualitatively and quantitatively reproduces the experimental features. The agreement implies that structures based on PIMD, which are similar to the traditional distorted tetrahedral view, are consistent with experimental observations. Supported by the DOE CMCSN through DOE award DE-SC0005180 (Princeton University) and in part by DOE Grant No. DE-FG03-97ER45623 (JJR) with computer support from NERSC.

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

    SciTech Connect

    Lapides, J.R.

    1981-01-01

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

  18. ANOMALIES IN THE ABSORPTION SPECTRUM AND BLEACHING KINETICS OF VISUAL PURPLE.

    PubMed

    Chase, A M

    1936-03-20

    Visual purple from winter frogs shows an intermediate yellow color during bleaching by light; summer extractions do not. This seasonal effect can be duplicated by variations in the hydrogen ion concentration and in the temperature of the solutions. Increasing the pH approximates the summer condition, while decreasing the pH approximates the winter condition. Temperature has no effect on the bleaching of alkaline solutions but greatly influences acid solutions. At low temperatures the bleaching of add solutions resembles the winter condition, while at higher temperatures it resembles the summer condition. A photic decomposition product of frog retinal extractions is an acid-base indicator: it is yellow in acid and colorless in alkaline solution. Its color is not dependent upon light. The hydrogen ion concentration of visual purple solutions does not change under illumination, nor is there a difference in the pH of summer and winter extractions. Bile salt extractions of visual purple are usually slightly acid. The conflicting results of past workers regarding the appearance of "visual yellow" may be due to seasonal variation with its differences in temperature, or to the presence of base in the extractions. It is also possible that vitamin A may be a factor in the seasonal variation. The photic decomposition of visual purple in bile salts solution, extracted from summer frogs, follows the kinetics of a first order reaction. Visual purple from winter frogs does not conform to first order kinetics. Photic decomposition of alkaline, winter visual purple extractions also follows a first order equation. Acid, winter extractions appear to conform to a second order equation, but this is probably an artefact due to interference by the intermediate yellow.

  19. Children with autism spectrum disorders show abnormal conditioned response timing on delay, but not trace, eyeblink conditioning.

    PubMed

    Oristaglio, J; Hyman West, S; Ghaffari, M; Lech, M S; Verma, B R; Harvey, J A; Welsh, J P; Malone, R P

    2013-09-17

    Children with autism spectrum disorder (ASD) and age-matched typically-developing (TD) peers were tested on two forms of eyeblink conditioning (EBC), a Pavlovian associative learning paradigm where subjects learn to execute an appropriately-timed eyeblink in response to a previously neutral conditioning stimulus (CS). One version of the task, trace EBC, interposes a stimulus-free interval between the presentation of the CS and the unconditioned stimulus (US), a puff of air to the eye which causes the subjects to blink. In delay EBC, the CS overlaps in time with the delivery of the US, usually with both stimuli terminating simultaneously. ASD children performed normally during trace EBC, exhibiting no differences from TD subjects with regard to the learning rate or the timing of the conditioned response. However, when subsequently tested on delay EBC, subjects with ASD displayed abnormally-timed conditioned eye blinks that began earlier and peaked sooner than those of TD subjects, consistent with previous findings. The results suggest an impaired ability of children with ASD to properly time conditioned eye blinks which appears to be specific to delay EBC. We suggest that this deficit may reflect a dysfunction of the cerebellar cortex in which increases in the intensity or duration of sensory input can temporarily disrupt the accuracy of motor timing over short temporal intervals.

  20. Children with autism spectrum disorders show abnormal conditioned response timing on delay, but not trace, eyeblink conditioning

    PubMed Central

    Oristaglio, Jeff; West, Susan Hyman; Ghaffari, Manely; Lech, Melissa S.; Verma, Beeta R.; Harvey, John A.; Welsh, John P.; Malone, Richard P.

    2013-01-01

    Children with autism spectrum disorder (ASD) and age-matched typically-developing (TD) peers were tested on two forms of eyeblink conditioning (EBC), a Pavlovian associative learning paradigm where subjects learn to execute an appropriately-timed eyeblink in response to a previously neutral conditioning stimulus (CS). One version of the task, trace EBC, interposes a stimulus-free interval between the presentation of the CS and the unconditioned stimulus (US), a puff of air to the eye which causes subjects to blink. In delay EBC, the CS overlaps in time with the delivery of the US, usually with both stimuli terminating simultaneously. ASD children performed normally during trace EBC, exhibiting no differences from typically-developing (TD) subjects with regard to learning rate or the timing of the CR. However, when subsequently tested on delay EBC, subjects with ASD displayed abnormally-timed conditioned eye blinks that began earlier and peaked sooner than those of TD subjects, consistent with previous findings. The results suggest an impaired ability of children with ASD to properly time conditioned eye blinks which appears to be specific to delay EBC. We suggest that this deficit may reflect a dysfunction of cerebellar cortex in which increases in the intensity or duration of sensory input can temporarily disrupt the accuracy of motor timing over short temporal intervals. PMID:23769889

  1. Anomalous band gap behavior in mixed Sn and Pb perovskites enables broadening of absorption spectrum in solar cells.

    PubMed

    Hao, Feng; Stoumpos, Constantinos C; Chang, Robert P H; Kanatzidis, Mercouri G

    2014-06-01

    Perovskite-based solar cells have recently been catapulted to the cutting edge of thin-film photovoltaic research and development because of their promise for high-power conversion efficiencies and ease of fabrication. Two types of generic perovskites compounds have been used in cell fabrication: either Pb- or Sn-based. Here, we describe the performance of perovskite solar cells based on alloyed perovskite solid solutions of methylammonium tin iodide and its lead analogue (CH3NH3Sn(1-x)Pb(x)I3). We exploit the fact that, the energy band gaps of the mixed Pb/Sn compounds do not follow a linear trend (the Vegard's law) in between these two extremes of 1.55 and 1.35 eV, respectively, but have narrower bandgap (<1.3 eV), thus extending the light absorption into the near-infrared (~1,050 nm). A series of solution-processed solid-state photovoltaic devices using a mixture of organic spiro-OMeTAD/lithium bis(trifluoromethylsulfonyl)imide/pyridinium additives as hole transport layer were fabricated and studied as a function of Sn to Pb ratio. Our results show that CH3NH3Sn(0.5)Pb(0.5)I3 has the broadest light absorption and highest short-circuit photocurrent density ~20 mA cm(-2) (obtained under simulated full sunlight of 100 mW cm(-2)).

  2. Communication: Does a single CH{sub 3}CN molecule attached to Ru(bipy){sub 3}{sup 2+} affect its absorption spectrum?

    SciTech Connect

    Stockett, M. H.; Brøndsted Nielsen, S.

    2015-05-07

    Tris(bipyridine)ruthenium(II) (Ru(bipy){sub 3}{sup 2+}) is a prototypical transition metal coordination complex whose photophysical properties have attracted considerable attention. A much debated issue is whether the metal-to-ligand charge transfer (MLCT) transition that accounts for the complex’s beautiful red color is fully delocalized across all three bipyridine ligands or located on just one ligand. Here, we show based on gas-phase action spectroscopy that attachment of a single acetonitrile molecule does not change the absorption spectrum from that of the bare ions, which is indicative of a delocalized state. However, the gas-phase spectra of the bare and one solvent molecule complexes are significantly blueshifted relative to that obtained in bulk acetonitrile, which suggests that in solution the polarizability of many solvent molecules working together can localize the MLCT state. Our data clearly show that more than one solvent molecule is needed to break the symmetry of the MLCT excited state and reproduce its solution-phase characteristics.

  3. Local Effects in the X-ray Absorption Spectrum of CaCl2, MgCl2, and NaCl Solutions

    SciTech Connect

    Kulik, H J; Correa Tedesco, A A; Schwegler, E; Prendergast, D; Galli, G

    2010-04-12

    Both first principles molecular dynamics and theoretical X-ray absorption spectroscopy have been used to investigate the aqueous solvation of cations in 0.5 M MgCl{sub 2}, CaCl{sub 2}, and NaCl solutions. We focus here on the species-specific effects that Mg{sup 2+}, Ca{sup 2+}, and Na{sup +}, have on the X-ray absorption spectrum of the respective solutions. For the divalent cations, we find that the hydrogen bonding characteristics of the more rigid magnesium first shell water molecules differ from those in the more flexible solvation shell surrounding calcium. In particular, the first solvation shell water molecules of calcium are accessible to forming acceptor hydrogen bonds, and this results in an enhancement of a post-edge peak near 540 eV. The absence of acceptor hydrogen bonds for magnesium first shell water molecules provides an explanation for the experimental and theoretical observation of a lack of enhancement at the post-main-edge peak. For the sodium monovalent cation we find that the broad tilt angle distribution results in a broadening of post-edge features, despite populations in donor-and-acceptor configurations consistent with calcium. We also present the re-averaged spectra of the MgCl{sub 2}, CaCl{sub 2}, and NaCl solutions and show that trends apparent with increasing concentration (0.5 M, 2.0 M, 4.0 M) are consistent with experiment. Finally, we examine more closely both the effect that cation coordination number has on the hydrogen bonding network and the relative perturbation strength of the cations on lone pair oxygen orbitals.

  4. An Fe XXVI Absorption Line in the Persistent Spectrum of the Dipping Low Mass X-ray Binary 1A 1744-361

    NASA Technical Reports Server (NTRS)

    Gavriil, Fotis P.; Strohmayer, Tod E.; Bhattacharyya, Sudip

    2009-01-01

    We report on Chandra X-ray Observatory (CXO) High-Energy Transmission Grating (HETG) spectra of the dipping Low Mass X-ray Binary (LMXB) 1A 1744-361 during its July 2008 outburst. We find that its persistent emission is well modeled by a blackbody (kT approx. 1.0 keV) plus power-law (Gamma approx. 1.7) with an absorption edge at 7.6 keV. In the residuals of the combined spectrum we find a significant absorption line at 6.961+/-0.002 keV, consistent with the Fe XXVI (hydrogen-like Fe) 2 - 1 transition. We place an upper limit on the velocity of a redshifted flow of v < 221 km/s. We find an equivalent width for the line of 27+2/-3 eV, from which we determine a column density of 7+/-1 x 10(exp 17)/sq cm via a curve-of-growth analysis. Using XSTAR simulations, we place a lower limit on the ionization parameter of > 10(exp 3.6) erg cm/s. The properties of this line are consistent with those observed in other dipping LMXBs. Using Rossi X-ray Timing Explorer (RXTE) data accumulated during this latest outburst we present an updated color-color diagram which clearly shows that IA 1744-361 is an "atoll" source. Finally, using additional dips found in the RXTE and CXO data we provide an updated orbital period estimate of 52+/-5 minutes.

  5. Design, synthesis, and properties of phthalocyanine complexes with main-group elements showing main absorption and fluorescence beyond 1000 nm.

    PubMed

    Furuyama, Taniyuki; Satoh, Koh; Kushiya, Tomofumi; Kobayashi, Nagao

    2014-01-15

    We present a comprehensive description of the unique properties of newly developed phthalocyanines (Pcs) containing main-group elements that absorb and emit in the near-IR region. Group 16 (S, Se, and Te) elements and group 15 (P, As, and Sb) elements were used as peripheral and central (core) substituents. With the introduction of group 16 elements into free-base Pc, a red-shift of the Q-band was observed, as a result of the electron-donating ability of group 16 elements particularly at the α positions. An X-ray crystallographic analysis of α-ArS-, ArSe-, and ArTe-linked free-base Pcs was also successfully performed, and the relationship between structure and optical properties was clarified. When a group 15 element ion was introduced into the center of the Pc ring, the resulting Pcs showed a single Q-band peak beyond 1000 nm (up to 1056 nm in CH2Cl2). In particular, [(ArS)8PcP(OMe)2](+) and [(ArS)8PcAs(OMe)2](+) exhibited a distinct fluorescence in the 960-1400 nm region with moderate quantum yields. The atomic radius of the group 15 element is important for determining the Pc structure, so that this can be controlled by the choice of group 15 elements. Electrochemical data revealed, while MO calculations suggested, that the red-shift of the Q-band is attributable to a decrease of the HOMO-LUMO gap due to significant and moderate stabilization of the LUMO and HOMO, respectively. The effect of peripheral substutuents and a central P(V) ion on the Q-band shift was independently predicted by MO calculations, while the magnitude of the total calculated shift was in good agreement with the experimental observations. The combination of spectral, electrochemical, and theoretical considerations revealed that all of the central group 15 elements, peripheral group 16 elements, and their positions are necessary to shift the Q-band beyond 1000 nm, indicating that the substitution effects of group 15 and 16 elements act synergistically. The Pcs having Q-bands beyond 1000 nm

  6. Design, synthesis, and properties of phthalocyanine complexes with main-group elements showing main absorption and fluorescence beyond 1000 nm.

    PubMed

    Furuyama, Taniyuki; Satoh, Koh; Kushiya, Tomofumi; Kobayashi, Nagao

    2014-01-15

    We present a comprehensive description of the unique properties of newly developed phthalocyanines (Pcs) containing main-group elements that absorb and emit in the near-IR region. Group 16 (S, Se, and Te) elements and group 15 (P, As, and Sb) elements were used as peripheral and central (core) substituents. With the introduction of group 16 elements into free-base Pc, a red-shift of the Q-band was observed, as a result of the electron-donating ability of group 16 elements particularly at the α positions. An X-ray crystallographic analysis of α-ArS-, ArSe-, and ArTe-linked free-base Pcs was also successfully performed, and the relationship between structure and optical properties was clarified. When a group 15 element ion was introduced into the center of the Pc ring, the resulting Pcs showed a single Q-band peak beyond 1000 nm (up to 1056 nm in CH2Cl2). In particular, [(ArS)8PcP(OMe)2](+) and [(ArS)8PcAs(OMe)2](+) exhibited a distinct fluorescence in the 960-1400 nm region with moderate quantum yields. The atomic radius of the group 15 element is important for determining the Pc structure, so that this can be controlled by the choice of group 15 elements. Electrochemical data revealed, while MO calculations suggested, that the red-shift of the Q-band is attributable to a decrease of the HOMO-LUMO gap due to significant and moderate stabilization of the LUMO and HOMO, respectively. The effect of peripheral substutuents and a central P(V) ion on the Q-band shift was independently predicted by MO calculations, while the magnitude of the total calculated shift was in good agreement with the experimental observations. The combination of spectral, electrochemical, and theoretical considerations revealed that all of the central group 15 elements, peripheral group 16 elements, and their positions are necessary to shift the Q-band beyond 1000 nm, indicating that the substitution effects of group 15 and 16 elements act synergistically. The Pcs having Q-bands beyond 1000 nm

  7. Plane-wave spectrum approach for the calculation of electromagnetic absorption under near-field exposure conditions.

    PubMed

    Chatterjee, I; Gandhi, O P; Hagmann, M J; Riazi, A

    1980-01-01

    The exposure of humans to electromagnetic near fields has not been sufficiently emphasized by researcher. We have used the plane-wave-spectrum approach to evaluate the electromagnetic field and determine the energy deposited in a lossy, homogeneous, semi-infinite slab placed in the near field of a source leaking radiation. Values of the fields and absorbed energy in the target are obtained by vector summation of the contributions of all the plane waves into which the prescribed field is decomposed. Use of a fast Fourier transform algorithm contributes to the high efficiency of the computations. The numerical results show that, for field distributions that are nearly constant over a physical extent of at least a free-space wavelength, the energy coupled into the target is approximately equal to the resulting from plane-wave exposed.

  8. Plane-wave spectrum approach for the calculation of electromagnetic absorption under near-field exposure conditions

    SciTech Connect

    Chatterjee, I.; Gandhi, O.P.; Hagmann, M.J.; Riazi, A.

    1980-01-01

    The exposure of humans to electromagnetic near fields has not been sufficiently emphasized by researcher. We have used the plane-wave-spectrum approach to evaluate the electromagnetic field and determine the energy deposited in a lossy, homogeneous, semi-infinite slab placed in the near field of a source leaking radiation. Values of the fields and absorbed energy in the target are obtained by vector summation of the contributions of all the plane waves into which the prescribed field is decomposed. Use of a fast Fourier transform algorithm contributes to the high efficiency of the computations. The numerical results show that, for field distributions that are nearly constant over a physical extent of at least a free-space wavelength, the energy coupled into the target is approximately equal to the resulting from plane-wave exposed.

  9. Solvent effects on the absorption spectrum and first hyperpolarizability of keto-enol tautomeric forms of anil derivatives: A Monte Carlo/quantum mechanics study.

    PubMed

    Adriano Junior, L; Fonseca, T L; Castro, M A

    2016-06-21

    Theoretical results for the absorption spectrum and electric properties of the enol and keto tautomeric forms of anil derivatives in the gas-phase and in solution are presented. The electronic properties in chloroform, acetonitrile, methanol, and water were determined by carrying out sequential Monte Carlo simulations and quantum mechanics calculations based on the time dependent density functional theory and on the second-order Møller-Plesset perturbation theory method. The results illustrate the role played by electrostatic interactions in the electronic properties of anil derivatives in a liquid environment. There is a significant increase of the dipole moment in solution (20%-100%) relative to the gas-phase value. Solvent effects are mild for the absorption spectrum and linear polarizability but they can be particularly important for first hyperpolarizability. A large first hyperpolarizability contrast between the enol and keto forms is observed when absorption spectra present intense lowest-energy absorption bands. Dynamic results for the first hyperpolarizability are in qualitative agreement with the available experimental results.

  10. Solvent effects on the absorption spectrum and first hyperpolarizability of keto-enol tautomeric forms of anil derivatives: A Monte Carlo/quantum mechanics study

    NASA Astrophysics Data System (ADS)

    Adriano Junior, L.; Fonseca, T. L.; Castro, M. A.

    2016-06-01

    Theoretical results for the absorption spectrum and electric properties of the enol and keto tautomeric forms of anil derivatives in the gas-phase and in solution are presented. The electronic properties in chloroform, acetonitrile, methanol, and water were determined by carrying out sequential Monte Carlo simulations and quantum mechanics calculations based on the time dependent density functional theory and on the second-order Møller-Plesset perturbation theory method. The results illustrate the role played by electrostatic interactions in the electronic properties of anil derivatives in a liquid environment. There is a significant increase of the dipole moment in solution (20%-100%) relative to the gas-phase value. Solvent effects are mild for the absorption spectrum and linear polarizability but they can be particularly important for first hyperpolarizability. A large first hyperpolarizability contrast between the enol and keto forms is observed when absorption spectra present intense lowest-energy absorption bands. Dynamic results for the first hyperpolarizability are in qualitative agreement with the available experimental results.

  11. Relative amplitudes of external satellites of superfine-structure multiplets in the saturated absorption spectrum of SiF4

    NASA Astrophysics Data System (ADS)

    Krylov, I. R.; Akulinin, D. A.; Chubykin, A. D.

    2015-08-01

    Variation of amplitudes of Doppler-free saturated absorption resonances as a result of changes in the gas pressure and power of light waves is studied theoretically and experimentally. The results of the investigation are used for the interpretation of weak satellites of superfine-structure multiplets in the spectrum related to tunnel transitions between energy states of a molecule corresponding to its rotation about equivalent symmetry axes. Relative amplitudes of satellites of the AFE and FEF multiplets of the superfine structure of the SiF4 molecule in the frequency tuning interval of a CO2 laser operating at the P(38) line of the 9.7-µm band are studied experimentally. It is confirmed that the variation of relative amplitudes of the satellites is caused mainly by the fact that the magnitudes of the self-induced transparency of the medium that are created by each light wave for itself are different for the main resonances of the multiplet and for their satellites. The discrepancy between the experimental and theoretical dependences of the relative amplitudes of the satellites upon variation of the gas pressure and power of light waves is analyzed. Based on the discovered discrepancy, it is suggested that molecular collisions with Bennett dip or peak transfer contribute to the formation of satellites of the FEF multiplet. Multiphoton processes participate in the formation of one of the multiplets of the FEF multiplet. It is suggested that the power of the light field partially lifts the ban on transitions participating in the formation of satellites of both studied multiplets. Processing of the experimental curves by the leastsquares method revealed spectrally unresolved satellites within the FEF multiplet, which represent crossover resonances between allowed and forbidden transitions. For these satellites, no additional dependence of the amplitude on the laser power or gas pressure was found. The dependence of the amplitude of these satellites is completely

  12. A full-dimensional multilayer multiconfiguration time-dependent Hartree study on the ultraviolet absorption spectrum of formaldehyde oxide

    SciTech Connect

    Meng, Qingyong; Meyer, Hans-Dieter

    2014-09-28

    Employing the multilayer multiconfiguration time-dependent Hartree (ML-MCTDH) method in conjunction with the multistate multimode vibronic coupling Hamiltonian (MMVCH) model, we perform a full dimensional (9D) quantum dynamical study on the simplest Criegee intermediate, formaldehyde oxide, in five lower-lying singlet electronic states. The ultraviolet (UV) spectrum is then simulated by a Fourier transform of the auto-correlation function. The MMVCH model is built based on extensive MRCI(8e,8o)/aug-cc-pVTZ calculations. To ensure a fast convergence of the final calculations, a large number of ML-MCTDH test calculations is performed to find an appropriate multilayer separations (ML-trees) of the ML-MCTDH nuclear wave functions, and the dynamical calculations are carefully checked to ensure that the calculations are well converged. To compare the computational efficiency, standard MCTDH simulations using the same Hamiltonian are also performed. A comparison of the MCTDH and ML-MCTDH calculations shows that even for the present not-too-large system (9D here) the ML-MCTDH calculations can save a considerable amount of computational resources while producing identical spectra as the MCTDH calculations. Furthermore, the present theoretical B{sup ~} {sup 1}A{sup ′}←X{sup ~} {sup 1}A{sup ′} UV spectral band and the corresponding experimental measurements [J. M. Beames, F. Liu, L. Lu, and M. I. Lester, J. Am. Chem. Soc. 134, 20045–20048 (2012); L. Sheps, J. Phys. Chem. Lett. 4, 4201–4205 (2013); W.-L. Ting, Y.-H. Chen, W. Chao, M. C. Smith, and J. J.-M. Lin, Phys. Chem. Chem. Phys. 16, 10438–10443 (2014)] are discussed. To the best of our knowledge, this is the first theoretical UV spectrum simulated for this molecule including nuclear motion beyond an adiabatic harmonic approximation.

  13. A full-dimensional multilayer multiconfiguration time-dependent Hartree study on the ultraviolet absorption spectrum of formaldehyde oxide.

    PubMed

    Meng, Qingyong; Meyer, Hans-Dieter

    2014-09-28

    Employing the multilayer multiconfiguration time-dependent Hartree (ML-MCTDH) method in conjunction with the multistate multimode vibronic coupling Hamiltonian (MMVCH) model, we perform a full dimensional (9D) quantum dynamical study on the simplest Criegee intermediate, formaldehyde oxide, in five lower-lying singlet electronic states. The ultraviolet (UV) spectrum is then simulated by a Fourier transform of the auto-correlation function. The MMVCH model is built based on extensive MRCI(8e,8o)/aug-cc-pVTZ calculations. To ensure a fast convergence of the final calculations, a large number of ML-MCTDH test calculations is performed to find an appropriate multilayer separations (ML-trees) of the ML-MCTDH nuclear wave functions, and the dynamical calculations are carefully checked to ensure that the calculations are well converged. To compare the computational efficiency, standard MCTDH simulations using the same Hamiltonian are also performed. A comparison of the MCTDH and ML-MCTDH calculations shows that even for the present not-too-large system (9D here) the ML-MCTDH calculations can save a considerable amount of computational resources while producing identical spectra as the MCTDH calculations. Furthermore, the present theoretical B̃(1)A'←X̃(1)A' UV spectral band and the corresponding experimental measurements [J. M. Beames, F. Liu, L. Lu, and M. I. Lester, J. Am. Chem. Soc. 134, 20045-20048 (2012); L. Sheps, J. Phys. Chem. Lett. 4, 4201-4205 (2013); W.-L. Ting, Y.-H. Chen, W. Chao, M. C. Smith, and J. J.-M. Lin, Phys. Chem. Chem. Phys. 16, 10438-10443 (2014)] are discussed. To the best of our knowledge, this is the first theoretical UV spectrum simulated for this molecule including nuclear motion beyond an adiabatic harmonic approximation. PMID:25273439

  14. A full-dimensional multilayer multiconfiguration time-dependent Hartree study on the ultraviolet absorption spectrum of formaldehyde oxide

    NASA Astrophysics Data System (ADS)

    Meng, Qingyong; Meyer, Hans-Dieter

    2014-09-01

    Employing the multilayer multiconfiguration time-dependent Hartree (ML-MCTDH) method in conjunction with the multistate multimode vibronic coupling Hamiltonian (MMVCH) model, we perform a full dimensional (9D) quantum dynamical study on the simplest Criegee intermediate, formaldehyde oxide, in five lower-lying singlet electronic states. The ultraviolet (UV) spectrum is then simulated by a Fourier transform of the auto-correlation function. The MMVCH model is built based on extensive MRCI(8e,8o)/aug-cc-pVTZ calculations. To ensure a fast convergence of the final calculations, a large number of ML-MCTDH test calculations is performed to find an appropriate multilayer separations (ML-trees) of the ML-MCTDH nuclear wave functions, and the dynamical calculations are carefully checked to ensure that the calculations are well converged. To compare the computational efficiency, standard MCTDH simulations using the same Hamiltonian are also performed. A comparison of the MCTDH and ML-MCTDH calculations shows that even for the present not-too-large system (9D here) the ML-MCTDH calculations can save a considerable amount of computational resources while producing identical spectra as the MCTDH calculations. Furthermore, the present theoretical tilde{B}{}^1A^' }leftarrow tilde{X}{}^1A^' } UV spectral band and the corresponding experimental measurements [J. M. Beames, F. Liu, L. Lu, and M. I. Lester, J. Am. Chem. Soc. 134, 20045-20048 (2012); L. Sheps, J. Phys. Chem. Lett. 4, 4201-4205 (2013); W.-L. Ting, Y.-H. Chen, W. Chao, M. C. Smith, and J. J.-M. Lin, Phys. Chem. Chem. Phys. 16, 10438-10443 (2014)] are discussed. To the best of our knowledge, this is the first theoretical UV spectrum simulated for this molecule including nuclear motion beyond an adiabatic harmonic approximation.

  15. [Using ultraviolet-visible ( UV-Vis) absorption spectrum to estimate the dissolved organic matter (DOM) concentration in water, soils and sediments of typical water-level fluctuation zones of the Three Gorges Reservoir areas].

    PubMed

    Li, Lu-lu; Jiang, Tao; Lu, Song; Yan, Jin-long; Gao, Jie; Wei, Shi-qiang; Wang, Ding-yong; Guo, Nian; Zhao, Zhena

    2014-09-01

    Dissolved organic matter (DOM) is a very important component in terrestrial ecosystem. Chromophoric dissolved organic matter (CDOM) is a significant constituent of DOM, which can be measured by ultraviolet-visible (UV-Vis) absorption spectrum. Thus the relationship between CDOM and DOM was investigated and established by several types of models including single-wavelength model, double-wavelength model, absorption spectrum slope (S value) model and three-wavelength model, based on the UV-Vis absorption coefficients of soil and sediment samples (sampled in July of 2012) and water samples (sampled in November of 2012) respectively. The results suggested that the three-wavelength model was the best for fitting, and the determination coefficients of water, soil and sediment data were 0. 788, 0. 933 and 0. 856, respectively. Meanwhile, the nominal best model was validated with the UV-Vis data of 32 soil samples and 36 water samples randomly collected in 2013, showing the RRMSE and MRE were 16. 5% and 16. 9% respectively for soil DOM samples, 10. 32% and 9. 06% respectively for water DOM samples, which further suggested the prediction accuracy was higher in water DOM samples as compared with that in soil DOM samples.

  16. The HD spectrum near 2.3 μm by CRDS-VECSEL: Electric quadrupole transition and collision-induced absorption

    NASA Astrophysics Data System (ADS)

    Vasilchenko, S.; Mondelain, D.; Kassi, S.; Čermák, P.; Chomet, B.; Garnache, A.; Denet, S.; Lecocq, V.; Campargue, A.

    2016-08-01

    The HD absorption spectrum is investigated near 2.3 μm with the help of a newly developed Cavity Ring Down Spectrometer (CRDS) using a VECSEL (Vertical External Cavity Surface Emitting Laser) as light source. The HD CRDS spectra were recorded for a series of ten pressure values in the range 50-650 Torr. The sensitivity of the recordings - noise equivalent absorption of the spectra on the order of αmin ≈ 5 × 10-10 cm-1 - has allowed for the first detection of the S(3) quadrupole electric transition of the HD fundamental band, at 4359.940 cm-1. The line center determined with an uncertainty of 0.002 cm-1 agrees with the most recent theoretical calculations. The retrieved value of the line intensity (2.5 × 10-27 cm/molecule at 296 K) agrees within 12% with the ab initio values included in the HITRAN spectroscopic database. We take the opportunity of this contribution to provide an exhaustive review of seventy-three HD absorption lines previously detected up to 20,000 cm-1. From the pressure dependence of the baseline of the CRDS spectra, the binary absorption coefficient of the HD collision induced absorption band is determined to be 1.17(4) × 10-6 cm-1amagat-2 at 4360 cm-1.

  17. The 13CH4 absorption spectrum in the Icosad range (6600-7692 cm-1) at 80 K and 296 K: Empirical line lists and temperature dependence

    NASA Astrophysics Data System (ADS)

    Campargue, A.; Béguier, S.; Zbiri, Y.; Mondelain, D.; Kassi, S.; Karlovets, E. V.; Nikitin, A. V.; Rey, M.; Starikova, E. N.; Tyuterev, Vl. G.

    2016-08-01

    The 13CH4 absorption spectrum has been recorded at 296 K and 80 K in the Icosad range between 6600 and 7700 cm-1. The achieved noise equivalent absorption of the spectra recorded by differential absorption spectroscopy (DAS) is about αmin ≈ 1.5 × 10-7 cm-1. Two empirical line lists were constructed including 17,792 and 24,139 lines at 80 K and 296 K, respectively. For comparison, the HITRAN database provides only 1040 13CH4 lines in the region determined from methane spectra with natural isotopic abundance. Empirical values of the lower state energy level, Eemp, were systematically derived from the intensity ratios of the lines measured at 80 K and 296 K. Overall 10,792 Eemp values were determined providing accurate temperature dependence for most of the 13CH4 absorption in the region (93% and 82% at 80 K and 296 K, respectively). The quality of the derived empirical values of the lower state rotational quantum number, Jemp, is illustrated by their clear propensity to be close to an integer. A good agreement is achieved between our small Jemp values, with previous accurate determinations obtained by applying the 2T method to jet and 80 K spectra. The line lists at 296 K and 80 K which are provided as Supplementary material will be used for future rovibrational assignments based on accurate variational calculations.

  18. Gas cell based on optical contacting for fundamental spectroscopy studies with initial reference absorption spectrum of H2O vapor at 1723 K and 0.0235 bar

    NASA Astrophysics Data System (ADS)

    Melin, Scott T.; Sanders, Scott T.

    2016-09-01

    A gas cell, using optically contacted sapphire windows to form a hot vapor seal, has been created for high temperature fundamental spectroscopy studies. It is designed to operate at temperatures from 280-2273 K and pressures from vacuum to 1.3 bar. Using the cell in conjunction with an external cavity diode laser spectrometer, a reference H2O vapor absorption spectrum at P=0.0235±0.0036 bar and T=1723±6 K was measured with 0.0001 cm-1 resolution over the 7326-7598 cm-1 range. Comparison of the measured spectrum to simulations reveals errors in both the HITEMP and BT2 databases. This work establishes heated static cell capabilities at temperatures well above the typical limit of approximately 1300 K set by quartz material properties. This paper addresses the design of the cell as well as the cell's limitations.

  19. Measurement and theoretical characterization of electronic absorption spectrum of neutral chrysene (C 18H 12) and its positive ion in H 3BO 3 matrix

    NASA Astrophysics Data System (ADS)

    Husain, Mudassir M.

    2007-09-01

    The ultraviolet and visible spectrum of chrysene and its radical cation formed by ultraviolet irradiation were measured in boric acid glass at room temperature. The theoretical electronic absorption spectrum of any polycyclic aromatic hydrocarbon (PAH) in boric acid matrix is calculated for the first time using semi empirical methods. Earlier reported theoretical results of electronic spectrum are calculated in free state and the results are compared with the spectrum of aromatic systems in glassy or other matrices. The interaction between the trapped PAHs (neutral and ions) and its environment induces strong perturbations of the energy levels which results in large shifts of the electronic transitions as compared to the ideal case of a free, isolated PAH molecule. This shifting due to perturbation has largely been ignored in earlier calculations, while comparing the calculations with the experimentally measured spectrum, in other matrices. The spectrum of singlet and doublet state of chrysene are computed in aqueous medium and also in free state to estimate the spectral shift. Several other geometric (bond length and bond angles) and spectroscopic parameters of chrysene like difference of HOMO-LUMO, ionization potential, dipole moment and polarizability are calculated using semi empirical methods, namely Austin Model 1 (AM1) and Parametric Method 3 (PM3). To get an idea about how the symmetry of chrysene molecule varies upon ionization, the mean polarizability ( α) as well as its tensor components αxx, αyy and αzz are calculated within a field of 0.005 a.u. The lasing action in neutral chrysene and in its cationic form is also discussed for the first time.

  20. The C ∼ 2B3u ← X ∼ 2B2g electronic absorption spectrum of butatriene cation in a neon matrix

    NASA Astrophysics Data System (ADS)

    Filipkowski, Karol; Fulara, Jan; Maier, John P.

    2015-04-01

    The C ∼ 2B3u ← X ∼ 2B2g electronic absorption of butatriene cation (BT+) has been observed in a 6 K neon matrix. The origin band lies at 511.9 nm. The electronic transition assignment is based on comparison with the photoelectron spectrum of butatriene and the vibrational frequencies of BT+ calculated with the CASPT2 (5, 6) method. Three vibrational modes of energy 207, 511 and 813 cm-1, with their overtones and combinations, are active in the C ∼ 2B3u state of BT+. It is shown that the emission observed from a glow discharge of 2-butyne at 491 nm and attributed to the origin band of this electronic transition [1] of BT+ is due to another species, because the difference of 850 cm-1 to the absorption spectrum is too large. No fluorescence of BT+ was detected in the matrix and it is expected that the C ∼ 2B3u electronic state relaxes non-radiatively on a fs time scale.

  1. The soft gamma-ray spectrum of A0535+26: Detection of an absorption feature at 110 keV by OSSE

    NASA Technical Reports Server (NTRS)

    Grove, J. E.; Strickman, M. S.; Johnson, W. N.; Kurfess, J. D.; Kinzer, R. L.; Starr, C. H.; Jung, G. V.; Kendziorra, E.; Maisack, M.; Staubert, R.

    1995-01-01

    We present soft gamma-ray observations by the Oriented Scintillation Spectrometer Experiment (OSSE) on the Compton Gamma Ray Observatory (GRO) of the transient X-ray binary pulsar A0535+26. The observations were made 1994 February 8-17, immediately prior to the peak of a giant outburst. The phase averaged spectrum is complex and cannot be described by a single-component model. We find that structure in the spectrum above 100 keV can best be modeled by an absorption feature near 110 keV, which we interepret as the signature of cyclotron resonant scattering. Because of OSSE's 45 keV threshold, we are unable to make a definitive statement on the presence of a 55 keV absorption line; however, we can conclude that if this line does exist, it must have a smaller optical depth than the line at 110 keV. A first harmonic (=fundamental) cyclotron resonance at 110 keV corresponds to a magnetic field strength at the surface of the neutron star of approximately 1 x 10(exp 13) G (approximately 5 x 10(exp 12) G if the first harmonic is at 55 keV).

  2. Contribution of a visual pigment absorption spectrum to a visual function: depth perception in a jumping spider.

    PubMed

    Nagata, Takashi; Arikawa, Kentaro; Terakita, Akihisa

    2013-01-01

    Absorption spectra of visual pigments are adaptively tuned to optimize informational capacity in most visual systems. Our recent investigation of the eyes of the jumping spider reveals an apparent exception: the absorption characteristics of a visual pigment cause defocusing of the image, reducing visual acuity generally in a part of the retina. However, the amount of defocus can theoretically provide a quantitative indication of the distance of an object. Therefore, we proposed a novel mechanism for depth perception in jumping spiders based on image defocus. Behavioral experiments revealed that the depth perception of the spider depended on the wavelength of the ambient light, which affects the amount of defocus because of chromatic aberration of the lens. This wavelength effect on depth perception was in close agreement with theoretical predictions based on our hypothesis. These data strongly support the hypothesis that the depth perception mechanism of jumping spiders is based on image defocus.

  3. Contribution of a visual pigment absorption spectrum to a visual function: depth perception in a jumping spider.

    PubMed

    Nagata, Takashi; Arikawa, Kentaro; Terakita, Akihisa

    2013-01-01

    Absorption spectra of visual pigments are adaptively tuned to optimize informational capacity in most visual systems. Our recent investigation of the eyes of the jumping spider reveals an apparent exception: the absorption characteristics of a visual pigment cause defocusing of the image, reducing visual acuity generally in a part of the retina. However, the amount of defocus can theoretically provide a quantitative indication of the distance of an object. Therefore, we proposed a novel mechanism for depth perception in jumping spiders based on image defocus. Behavioral experiments revealed that the depth perception of the spider depended on the wavelength of the ambient light, which affects the amount of defocus because of chromatic aberration of the lens. This wavelength effect on depth perception was in close agreement with theoretical predictions based on our hypothesis. These data strongly support the hypothesis that the depth perception mechanism of jumping spiders is based on image defocus. PMID:27493545

  4. Ultrafast transient absorption spectrum of the room temperature Ionic liquid 1-hexyl-3-methylimidazolium bromide: Confounding effects of photo-degradation

    NASA Astrophysics Data System (ADS)

    Musat, Raluca M.; Crowell, Robert A.; Polyanskiy, Dmitriy E.; Thomas, Marie F.; Wishart, James F.; Katsumura, Yosuke; Takahashi, Kenji

    2015-12-01

    The photochemistry of the charge transfer (CT) band of the room temperature ionic liquid (RTIL) 1-hexyl-3-methylimidazolium bromide (HMIm+/Br-) is investigated using near-IR to vis ultrafast transient absorption (TA) and steady-state UV absorption spectroscopies. Continuous irradiation of the CT band at 266 nm results in the formation of photo-products that absorb strongly at 266 nm. It is shown that these photo-products, which are apparently very stable, adversely affect ultrafast TA measurements. Elimination of these effects reveals at least two transient species that exist within the TA detection window of 100 fs to 3 ns and 500-1250 nm. One of the components is a short-lived (<1 ps) species that absorbs at 1080 nm. The second band exhibits a multicomponent spectrum that is very broad with an absorption maximum around 600 nm and a lifetime that is longer than the 3 ns window of our TA spectrometer. Within the signal to noise ratio of the TA spectrometer little to no solvated electron is generated by the CT mechanism.

  5. Low-temperature high-resolution absorption spectrum of 14NH3 in the ν1+ν3 band region (1.51 μm)

    NASA Astrophysics Data System (ADS)

    Földes, T.; Golebiowski, D.; Herman, M.; Softley, T. P.; Di Lonardo, G.; Fusina, L.

    2014-09-01

    Jet-cooled spectra of 14NH3 and 15NH3 in natural abundance were recorded using cavity ring-down (CRDS, 6584-6670 cm-1) and cavity enhanced absorption (CEAS, 6530-6700 cm-1) spectroscopy. Line broadening effects in the CRDS spectrum allowed lines with J″-values between 0 and 3 to be identified. Intensity ratios in 14NH3 between the jet-cooled CRDS and literature room-temperature data from Sung et al. (J. Quant. Spectrosc. Radiat. Transfer, 113 (2012), 1066) further assisted the line assignments. Ground state combination differences were extensively used to support the assignments, providing reliable values for J, K and inversion symmetry of the ground state vibrational levels. CEAS data helped in this respect for the lowest J lines, some of which are saturated in the CRDS spectrum. Further information on a/s doublets arose from the observed spectral structures. Thirty-two transitions of 14NH3 were assigned in this way and a limited but significant number (19) of changes in the assignments results, compared to Sung et al. or to Cacciani et al. (J. Quant. Spectrosc. Radiat. Transfer, 113 (2012), 1084). Sixteen known and 25 new low-J transitions were identified for 15NH3 in the CRDS spectrum but the much scarcer literature information did not allow for any more refined assignment. The present line position measurements improve on literature values published for 15NH3 and on some line positions for 14NH3.

  6. Neutralization of feline infectious peritonitis virus: preparation of monoclonal antibody that shows cell tropism in neutralizing activity after viral absorption into the cells.

    PubMed

    Kida, K; Hohdatsu, T; Kashimoto-Tokunaga, J; Koyama, H

    2000-01-01

    Feline infectious peritonitis virus (FIPV) infection of feline macro-phages is enhanced by mouse anti-FIPV monoclonal antibody (MAb). This anti-body-dependent enhancement (ADE) of FIPV infection is dependent on mouse MAb subclass, and MAb of IgG2a subclass has a strong ADE activity. Furthermore, MAb showing strong neutralizing activity in Felis catus whole fetus (fcwf-4) cells and Crandell feline kidney (CrFK) cells shows strong enhancing activity in feline macrophages, indicating that the neutralizing epitope and the enhancing epitope are closely related. In this study, we prepared MAb FK50-4 that showed a strong neutralizing activity in feline macrophages, despite the fact that the MAb belonged to the IgG2a subclass. However, MAb FK50-4 did not exhibit neutralizing activity in CrFK cells or fcwf-4 cells, thus showing a very unusual property. MAb FK50-4 recognized FIPV small integral membrane glycoprotein (M protein). Even when feline macrophages were pretreated with MAb FK50-4 prior to FIPV inoculation, this antibody prevented FIPV infection. This reaction disappeared after treatment of FK50-4 with protein A. The neutralizing activity of FK50-4 was also effective on feline macrophages after the cells were inoculated with FIPV. These findings indicated that the FIPV replication mechanism differs between feline macrophages and CrFK/fcwf-4 cells and that a neutralizing epitope that can prevent FIPV infection of feline macrophages after viral absorption is present on M protein.

  7. The CO2 absorption spectrum in the 2.3 μm transparency window by high sensitivity CRDS: (I) Rovibrational lines

    NASA Astrophysics Data System (ADS)

    Vasilchenko, S.; Konefal, M.; Mondelain, D.; Kassi, S.; Čermák, P.; Tashkun, S. A.; Perevalov, V. I.; Campargue, A.

    2016-11-01

    The absorption of carbon dioxide is very weak near 2.3 μm which makes this transparency window of particular interest for the study of Venus' lower atmosphere. As a consequence of the weakness of the transitions located in this region, previous experimental data are very scarce and spectroscopic databases provide calculated line lists which should be tested and validated by experiment. In this work, we use the Cavity Ring Down Spectroscopy (CRDS) technique for a high sensitivity characterization of the CO2 absorption spectrum in two spectral intervals of the 2.3 μm window: 4248-4257 and 4295-4380 cm-1 which were accessed using a Distributed Feed Back (DFB) diode laser and a Vertical External Cavity Surface Emitting Laser (VECSEL) as light sources, respectively. The achieved sensitivity (noise equivalent absorption, αmin, on the order of 5×10-10 cm-1) allowed detecting numerous new transitions with intensity values down to 5×10-30 cm/molecule. The rovibrational assignments were performed by comparison with available theoretical line lists in particular those obtained at IAO Tomsk using the global effective operator approach. Hot bands of the main isotopologue and 16O12C18O bands were found to be missing in the HITRAN database while they contribute importantly to the absorption in the region. Additional CRDS spectra of a CO2 sample highly enriched in 18O were recorded in order to improve the spectroscopy of this isotopologue. As a result about 700 lines of 16O12C18O, 16O12C17O, 17O12C18O, 12C18O2 and 13C18O2 were newly measured. The status of the different databases (HITRAN, CDSD, variational calculations) in the important 2.3 μm transparency window is discussed. Possible improvements to correct evidenced deficiencies are suggested.

  8. A study of the H2O absorption line shifts in the visible spectrum region due to air pressure

    NASA Technical Reports Server (NTRS)

    Grossmann, B. E.; Browell, E. V.; Bykov, A. D.; Kapitanov, V. A.; Korotchenko, E. A.

    1990-01-01

    Results of measured and calculated shift coefficients are presented for 170 absorption lines of H2O in five vibrational-rotational bands. The measurements have been carried out using highly sensitive laser spectrometers with a resolution of at least 0.01/cm; the calculations are based on the Anderson-Tsao-Curnutte-Frost method. Good agreement is obtained between the theoretical and experimental values of the shift coefficients of H2O lines due to N2, O2, and air pressure.

  9. X-ray Absorption Spectroscopy of Zinc in Airborne Particulate Matter Shows Tire Debris Concentrated in > 0.5 μm Fraction

    NASA Astrophysics Data System (ADS)

    Pingitore, N. E.; Clague, J. W.; Gill, T. E.; Amaya, M. A.; Cahill, T. A.

    2009-12-01

    Using X-ray absorption spectroscopy (XAS), we speciated Zn in size-resolved fractions of particulate matter (PM) from El Paso, Texas. Spectral patterns indicated that Zn in tire debris is the dominant form of Zn in PM coarser than 0.5 μm in aerodynamic diameter. Although concentrated in the > 0.5 μm fraction, a large portion of the tire debris in PM is small enough to penetrate and deposit in the lower respiratory tract. We collected 3 sets of size-resolved samples of airborne particulate matter (PM) over periods of several days to several weeks in November 2008, and April and May 2009. Local PM compositions typically are dominated by anthropogenic input in November and geologic sources in April, and a mixture in May. The collection site is in the urban core of El Paso, TX, contiguous to the University of Texas at El Paso, 0.6 km from Interstate Highway 10, 0.4 km from State Highway 20, and 1 km from Cd. Juarez, Chihuahua, Mexico. The DRUM sampler (Davis Rotating Uniform size-cut Monitor) employs a rotating Lundgren-type impactor, draws 10 l per minute, and deposits PM on plastic strips mounted on rotating drums. The sampler collected and segregated ambient PM into 8 size cuts: 12-5 μm, 5-2.5, 2.5-1.15, 1.15-0.75, 0.75-0.56, 0.56-0.34, 0.34-0.26, and 0.26-0.09. We conducted the X-ray absorption spectroscopy (XAS) experiments at the Stanford Synchrotron Radiation Lightsource on beam line 7-3. Spectra of the 24 samples of PM and numerous model compounds were collected at the Zn K absorption edge in fluorescence mode using a 30-element Ge solid-state detector. The overall spectral patterns from the 3 seasons were similar to one another. But strikingly, each set of 8 XAS spectra displayed an obvious change in the Zn speciation at the 0.56-0.75 μm size cut. We compared the PM spectra to those of our suite of known model compounds and materials. The spectral pattern of the coarser size cuts was quite similar to those of the tires we tested. The Zn in the tires

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed

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

    2016-01-01

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

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

    PubMed

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

    2016-01-01

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

  13. Study of the H-F stretching band in the absorption spectrum of (CH3)2O...HF in the gas phase.

    PubMed

    Bulychev, V P; Gromova, E I; Tokhadze, K G

    2008-02-14

    The absorption spectra of the (CH3)2O...HF complex in the range of 4200-2800 cm(-1) were recorded in the gas phase at a resolutions of 0.1 cm(-1) at T = 190-340 K. The spectra obtained were used to analyze their structure and to determine the temperature dependencies of the first and second spectral moments. The band shape of the (CH3)2O...HF complex in the region of the nu1(HF) stretching mode was reconstructed nonempirically. The nu1 and nu3 stretching vibrations and four bending vibrations responsible for the formation of the band shape were considered. The equilibrium geometry and the 1D-4D potential energy surfaces were calculated at the MP2 6-311++G(2d,2p) level with the basis set superposition error taken into account. On the basis of these surfaces, a number of one- and multidimensional anharmonic vibrational problems were solved by the variational method. Solutions of auxiliary 1D and 2D vibrational problems showed the strong coupling between the modes. The energy levels, transition frequencies and intensities, and the rotational constants for the combining vibrational states necessary to reconstruct the spectrum were obtained from solutions of the 4D problem (nu1, nu3, nu5(B2), nu6(B2)) and the 2D problem (nu5(B1), nu6(B1)). The theoretical spectra reconstructed for different temperatures as a superposition of rovibrational bands associated with the fundamental, hot, sum, and difference transitions reproduce the shape and separate spectral features of the experimental spectra. The calculated value of the nu1 frequency is 3424 cm(-1). Along with the frequencies and absolute intensities, the calculation yields the vibrationally averaged values of the separation between the centers of mass of the monomers Rc.-of-m., R(O...F), and r(HF) for different states. In particular, upon excitation of the nu1 mode, Rc.-of-m. becomes shorter by 0.0861 A, and r(HF) becomes longer by 0.0474 A.

  14. FE K EMISSION AND ABSORPTION FEATURES IN THE XMM-EPIC SPECTRUM OF THE SEYFERT GALAXY IC 4329A

    NASA Technical Reports Server (NTRS)

    Markowitz, A.; Reeves, J. N.; Braito, V.

    2001-01-01

    We present a re-analysis of the XMM-Newton long-look of the X-ray bright Seyfert galaxy IC 4329a. The Fe K bandpass is dominated by two peaks, consistent with emission from neutral or near-neutral Fe Ka and KP. A relativistic diskline model whereby both peaks are the result of one doubly-peaked diskline profile is found to be a poor description of the data. Models using two relativistic disklines are found to describe the emission profile well. A low-inclination, moderately-relativistic dual-diskline model is possible if the contribution from narrow components, due to distant material, is small or absent. A high-inclination, moderately relativistic profile for each peak is possible if there are roughly equal contributions from both the broad and narrow components. Upper limits on Fe XXV and Fe XXVI emission and absorption at the systemic velocity of IC 4329a are obtained. We also present the results of RXTE monitoring of this source obtained so far; the combined XMM-Newton and RXTE data sets allow us to explore the time-resolved spectral behavior of this source on time scales ranging from hours to 2 years. We find no strong evidence for variability of the Fe Ka emission line on any time scale probed, likely due to the minimal level of continuum variability. We detect a narrow absorption line, at a energy of 7.68 keV in the rest frame of the source; its significance has been confirmed using Monte Carlo simulations. This feature is most likely due to absorption from Fe XXVI blueshifted to approximately 0.1c relative to the systemic velocity, making IC 4329a the lowest-redshift AGN known with a high-velocity, highly-ionized outflow component. As is often the case with similar outflows seen in high-luminosity quasars, the estimated mass outflow rate is larger than the inflow accretion rate, signaling that the outflow represents a substantial portion of the total energy budget of the AGN. The outflow could arise from a radiatively-driven disk wind, or it may be in the

  15. Discovery of a cyclotron absorption line in the spectrum of the binary X-ray pulsar 4U 1538 - 52 observed by Ginga

    NASA Technical Reports Server (NTRS)

    Clark, George W.; Woo, Jonathan W.; Nagase, Fumiaki; Makishima, Kazuo; Sakao, Taro

    1990-01-01

    A cyclotron absorption line near 20 keV has been found in the spectrum of the massive eclipsing binary X-ray pulsar 4U 1538 - 52 in observations with the Ginga observatory. The line is detected throughout the 529 s pulse cycle with a variable equivalent width that has its maximum value during the smaller peak of the two-peak pulse profile. It is found that the profile of the pulse and the phase-dependence of the cyclotron line can be explained qualitatively by a pulsar model based on recent theoretical results on the properties of pencil beams emitted by accretion-heated slabs of magnetized plasma at the magnetic poles of a neutron star. The indicated field at the surface of the neutron star is 1.7 (1 + z) x 10 to the 12th G, where z is the gravitational redshift.

  16. The 5 f r arrow 6 d absorption spectrum of Pa sup 4+ /Cs sub 2 ZrCl sub 6

    SciTech Connect

    Edelstein, N.; Kot, W.K. ); Krupa, J. )

    1992-01-01

    The 5{ital f}{sup 1}{r arrow}6{ital d}{sup 1} absorption spectrum of {sup 231}Pa{sup 4+} diluted in a single crystal of Cs{sub 2}ZrCl{sub 6} has been measured at 4.2 K. Three bands corresponding to the 6{ital d}({Gamma}{sub 8{ital g}}, {Gamma}{sub 7{ital g}}, and {Gamma}{sup {prime}}{sub 8{ital g}} ) levels are assigned. Extensive vibronic structure has been observed for the lowest 5{ital f}{r arrow}6{ital d} transition and this structure is compared to that recently reported for the 6{ital d}{sup 1}{r arrow}5{ital f}{sup 1} emission spectra in the same system.

  17. Experimental and theoretical study of absorption spectrum of the (CH3)2CO···HF complex. Influence of anharmonic interactions on the frequency and intensity of the C=O and H-F stretching bands.

    PubMed

    Bulychev, V P; Svishcheva, E A; Tokhadze, K G

    2014-01-01

    IR absorption spectra of mixtures (CH3)2CO/HF and free (CH3)2CO molecules are recorded in the region of 4000-900 cm(-1) with a Bruker IFS-125 HR vacuum Fourier spectrometer at room temperature with a resolution up to 0.02 cm(-1). Spectral characteristics of the 2ν(C=O) overtone band of free acetone are reliably measured. The ν1(HF) and ν(C=O) absorption bands of the (CH3)2CO···HF complex are obtained by subtracting the absorption bands of free HF and acetone and absorption lines of atmospheric water from the experimental spectrum of mixtures. The experimental data are compared with theoretical results obtained from variational solutions of 1D-4D vibrational Schrödinger equations. The anharmonic potential energy and dipole moment surfaces used in the calculations were computed in the MP2/6-311++G(2d,2p) approximation with corrections for the basis set superposition error. Comparison of the data derived from solutions for different combinations of vibrational degrees of freedom shows that taking the inter-mode anharmonic interactions into account has different effects on the transition frequencies and intensities. Particular attention has been given to elucidation of the influence of anharmonic coupling of the H-F and C=O stretches with the low-frequency intermolecular modes on their frequencies and intensities and the strength of resonance between the fundamental H-F and the first overtone C=O transitions.

  18. Experimental and theoretical study of absorption spectrum of the (CH3)2CO···HF complex. Influence of anharmonic interactions on the frequency and intensity of the C=O and H-F stretching bands.

    PubMed

    Bulychev, V P; Svishcheva, E A; Tokhadze, K G

    2014-01-01

    IR absorption spectra of mixtures (CH3)2CO/HF and free (CH3)2CO molecules are recorded in the region of 4000-900 cm(-1) with a Bruker IFS-125 HR vacuum Fourier spectrometer at room temperature with a resolution up to 0.02 cm(-1). Spectral characteristics of the 2ν(C=O) overtone band of free acetone are reliably measured. The ν1(HF) and ν(C=O) absorption bands of the (CH3)2CO···HF complex are obtained by subtracting the absorption bands of free HF and acetone and absorption lines of atmospheric water from the experimental spectrum of mixtures. The experimental data are compared with theoretical results obtained from variational solutions of 1D-4D vibrational Schrödinger equations. The anharmonic potential energy and dipole moment surfaces used in the calculations were computed in the MP2/6-311++G(2d,2p) approximation with corrections for the basis set superposition error. Comparison of the data derived from solutions for different combinations of vibrational degrees of freedom shows that taking the inter-mode anharmonic interactions into account has different effects on the transition frequencies and intensities. Particular attention has been given to elucidation of the influence of anharmonic coupling of the H-F and C=O stretches with the low-frequency intermolecular modes on their frequencies and intensities and the strength of resonance between the fundamental H-F and the first overtone C=O transitions. PMID:24128921

  19. Assignment and modeling of the absorption spectrum of 13CH4 at 80 K in the region of the 2ν3 band (5853-6201 cm-1)

    NASA Astrophysics Data System (ADS)

    Starikova, E.; Nikitin, A. V.; Rey, M.; Tashkun, S. A.; Mondelain, D.; Kassi, S.; Campargue, A.; Tyuterev, Vl. G.

    2016-07-01

    The absorption spectrum of the 13CH4 methane isotopologue has been recently recorded by Differential Absorption Spectroscopy (DAS) at 80 K in the 5853-6201 cm-1 spectral range. An empirical list of 3717 lines was constructed for this spectral range corresponding to the upper part of the Tetradecad dominated by the 2ν3 band near 5987 cm-1. In this work, we present rovibrational analyses of these spectra obtained via two theoretical approaches. Assignments of strong and medium lines were achieved with variational calculations using ab initio potential energy (PES) and dipole moment surfaces. For further analysis a non-empirical effective Hamiltonian (EH) of the methane polyads constructed by high-order Contact Transformations (CT) from an ab initio PES was employed. Initially predicted values of EH parameters were empirically optimized using 2898 assigned line positions fitted with an rms deviation of 5×10-3 cm-1. More than 1860 measured line intensities were modeled using the effective dipole transition moments approach with the rms deviation of about 10%. These new data were used for the simultaneous fit of the 13CH4 Hamiltonian parameters of the {Ground state/Dyad/Pentad/Octad/Tetradecad} system and the dipole moment parameters of the {Ground state-Tetradecad} system. Overall, 10 vibrational states and 28 vibration sublevels of the 13CH4 Tetradecad are determined. The comparison of their energy values with corresponding theoretical calculations is discussed.

  20. Cavity Ringdown Absorption Spectrum of the T_1(n,π*) ← S_0 Transition of Acrolein: Analysis of the 0^0_0 Band Rotational Contour

    NASA Astrophysics Data System (ADS)

    Hlavacek, Nikolaus C.; McAnally, Michael O.; Drucker, Stephen

    2012-06-01

    Acrolein (propenal, CH_2=CH---CH=O) is the simplest conjugated enal molecule and serves as a prototype for investigating the photochemical properties of larger enals and enones. Acrolein has a coplanar arrangement of heavy atoms in its ground electronic state. Much of the photochemistry is mediated by the T_1(π,π*) state, which has a CH_2--twisted equilibrium structure. In solution, the T_1(π,π*) state is typically accessed via intersystem crossing from an intially prepared planar S_1(n,π*) state. An intermediate in this photophysical transformation is the lowest ^3 (n,π*) state, a planar species with adiabatic excitation energy below S_1 and above T_1(π,π*). The present work focuses on this ^3 (n,π*) intermediate state; it is designated T_1(n,π*) as the lowest-energy triplet state of acrolein having a planar equilibrium structure. The T_1(n,π*) ← S_0 band system, with origin near 412 nm, was first recorded in the 1970s at medium (0.5 cm-1) resolution using a long-path absorption cell. Here we report the cavity ringdown spectrum of the 0^0_0 band, recorded using a pulsed dye laser with 0.1 cm-1 spectral bandwidth. The spectrum was measured under both bulk-gas (room-temperature) and jet-cooled conditions. The band contour in each spectrum was analyzed by using a computer program developed for simulating and fitting the rotational structure of singlet-triplet transitions. The assignment of several resolved sub-band heads in the room-temperature spectrum permitted approximate fitting of the inertial constants for the T_1(n,π*) state. The determined values (cm-1) are A=1.662, B=0.1485, C=0.1363. For the parameters A and (B+C)/2, estimated uncertainties of ± 0.003 cm-1 and ± 0.0004 cm-1, respectively, correspond to a range of values that produce qualitatively satisfactory global agreement with the observed room-temperature contour. The fitted inertial constants were used to simulate the rotational contour of the 0^0_0 band under jet-cooled conditions

  1. A Combination of Chemometrics and Quantum Mechanics Methods Applied to Analysis of Femtosecond Transient Absorption Spectrum of Ortho-Nitroaniline.

    PubMed

    Yi, Jing; Xiong, Ying; Cheng, Kemei; Li, Menglong; Chu, Genbai; Pu, Xuemei; Xu, Tao

    2016-01-19

    A combination of the advanced chemometrics method with quantum mechanics calculation was for the first time applied to explore a facile yet efficient analysis strategy to thoroughly resolve femtosecond transient absorption spectroscopy of ortho-nitroaniline (ONA), served as a model compound of important nitroaromatics and explosives. The result revealed that the ONA molecule is primarily excited to S3 excited state from the ground state and then ultrafast relaxes to S2 state. The internal conversion from S2 to S1 occurs within 0.9 ps. One intermediate state S* was identified in the intersystem crossing (ISC) process, which is different from the specific upper triplet receiver state proposed in some other nitroaromatics systems. The S1 state decays to the S* one within 6.4 ps and then intersystem crossing to the lowest triplet state within 19.6 ps. T1 was estimated to have a lifetime up to 2 ns. The relatively long S* state and very long-lived T1 one should play a vital role as precursors to various nitroaromatic and explosive photoproducts.

  2. A Combination of Chemometrics and Quantum Mechanics Methods Applied to Analysis of Femtosecond Transient Absorption Spectrum of Ortho-Nitroaniline

    PubMed Central

    Yi, Jing; Xiong, Ying; Cheng, Kemei; Li, Menglong; Chu, Genbai; Pu, Xuemei; Xu, Tao

    2016-01-01

    A combination of the advanced chemometrics method with quantum mechanics calculation was for the first time applied to explore a facile yet efficient analysis strategy to thoroughly resolve femtosecond transient absorption spectroscopy of ortho-nitroaniline (ONA), served as a model compound of important nitroaromatics and explosives. The result revealed that the ONA molecule is primarily excited to S3 excited state from the ground state and then ultrafast relaxes to S2 state. The internal conversion from S2 to S1 occurs within 0.9 ps. One intermediate state S* was identified in the intersystem crossing (ISC) process, which is different from the specific upper triplet receiver state proposed in some other nitroaromatics systems. The S1 state decays to the S* one within 6.4 ps and then intersystem crossing to the lowest triplet state within 19.6 ps. T1 was estimated to have a lifetime up to 2 ns. The relatively long S* state and very long-lived T1 one should play a vital role as precursors to various nitroaromatic and explosive photoproducts. PMID:26781083

  3. Electromagnetic resonance modes on a two-dimensional tandem grating and its application for broadband absorption in the visible spectrum.

    PubMed

    Han, Sunwoo; Lee, Bong Jae

    2016-01-25

    In this work, we numerically investigate the electromagnetic resonances on two-dimensional tandem grating structures. The base of a tandem grating consists of an opaque Au substrate, a SiO(2) spacer, and a Au grating (concave type); that is, a well-known fishnet structure forming Au/SiO(2)/Au stack. A convex-type Au grating (i.e., topmost grating) is then attached on top of the base fishnet structure with or without additional SiO(2) spacer, resulting in two types of tandem grating structures. In order to calculate the spectral reflectance and local magnetic field distribution, the finite-difference time-domain method is employed. When the topmost Au grating is directly added onto the base fishnet structure, the surface plasmon and magnetic polariton in the base structure are branched out due to the geometric asymmetry with respect to the SiO(2) spacer. If additional SiO(2) spacer is added between the topmost Au grating and the base fishnet structure, new magnetic resonance modes appear due to coupling between two vertically aligned Au/SiO(2)/Au stacks. With the understanding of multiple electromagnetic resonance modes on the proposed tandem grating structures, we successfully design a broadband absorber made of Au and SiO(2) in the visible spectrum.

  4. A novel, selective inhibitor of fibroblast growth factor receptors that shows a potent broad spectrum of antitumor activity in several tumor xenograft models.

    PubMed

    Zhao, Genshi; Li, Wei-Ying; Chen, Daohong; Henry, James R; Li, Hong-Yu; Chen, Zhaogen; Zia-Ebrahimi, Mohammad; Bloem, Laura; Zhai, Yan; Huss, Karen; Peng, Sheng-Bin; McCann, Denis J

    2011-11-01

    The fibroblast growth factor receptors (FGFR) are tyrosine kinases that are present in many types of endothelial and tumor cells and play an important role in tumor cell growth, survival, and migration as well as in maintaining tumor angiogenesis. Overexpression of FGFRs or aberrant regulation of their activities has been implicated in many forms of human malignancies. Therefore, targeting FGFRs represents an attractive strategy for development of cancer treatment options by simultaneously inhibiting tumor cell growth, survival, and migration as well as tumor angiogenesis. Here, we describe a potent, selective, small-molecule FGFR inhibitor, (R)-(E)-2-(4-(2-(5-(1-(3,5-Dichloropyridin-4-yl)ethoxy)-1H-indazol-3yl)vinyl)-1H-pyrazol-1-yl)ethanol, designated as LY2874455. This molecule is active against all 4 FGFRs, with a similar potency in biochemical assays. It exhibits a potent activity against FGF/FGFR-mediated signaling in several cancer cell lines and shows an excellent broad spectrum of antitumor activity in several tumor xenograft models representing the major FGF/FGFR relevant tumor histologies including lung, gastric, and bladder cancers and multiple myeloma, and with a well-defined pharmacokinetic/pharmacodynamic relationship. LY2874455 also exhibits a 6- to 9-fold in vitro and in vivo selectivity on inhibition of FGF- over VEGF-mediated target signaling in mice. Furthermore, LY2874455 did not show VEGF receptor 2-mediated toxicities such as hypertension at efficacious doses. Currently, this molecule is being evaluated for its potential use in the clinic.

  5. Invasive ductal carcinomas of the breast showing partial reversed cell polarity are associated with lymphatic tumor spread and may represent part of a spectrum of invasive micropapillary carcinoma.

    PubMed

    Acs, Geza; Esposito, Nicole N; Rakosy, Zsuzsa; Laronga, Christine; Zhang, Paul J

    2010-11-01

    Invasive micropapillary carcinomas (IMPC) of the breast are aggressive tumors frequently associated with lymphatic invasion and nodal metastasis even when micropapillary (MP) differentiation is very focal within the tumors. We have noticed that some breast carcinomas showing lymphatic spread but lacking histologic features of IMPC have occasional tumor cell clusters reminiscent of those of IMPC without the characteristic prominent retraction artifact. To study the clinicopathologic significance of such features, we prospectively selected 1323 invasive ductal carcinomas and determined the presence and extent of MP differentiation and retraction artifact in the tumors. One representative tumor block per case was used for immunostaining for epithelial membrane antigen (EMA). Partial reverse cell polarity (PRCP) was defined as prominent linear EMA reactivity on at least part of the periphery of tumor cell clusters usually associated with decreased cytoplasmic staining. The clinicopathologic features of carcinomas with PRCP were compared with IMPC and invasive ductal (no special type) carcinomas without this feature. Of the 1323 cases, 96 (7.3%) and 92 (7.0%) showed MP features and the presence of PRCP, respectively. We found that the presence of both PRCP and MP features were strongly associated with decreased cytoplasmic EMA immunoreactivity and the presence of lymphatic invasion and nodal metastasis, even if such features were present only very focally. Our results suggest that breast carcinomas with PRCP may have the same implication as MP differentiation and these tumors may represent part of a spectrum of IMPC. Complete or partial reversal of cell polarity may play a significant role in lymphatic tumor spread.

  6. Pathogenic and commensal Escherichia coli from irrigation water show potential in transmission of extended spectrum and AmpC β-lactamases determinants to isolates from lettuce

    PubMed Central

    Njage, Patrick M K; Buys, Elna M

    2015-01-01

    There are few studies on the presence of extended-spectrum β-lactamases and AmpC β-lactamases (ESBL/AmpC) in bacteria that contaminate vegetables. The role of the production environment in ESBL/AmpC gene transmission is poorly understood. The occurrence of ESBL/AmpC in Escherichia coli (n = 46) from lettuce and irrigation water and the role of irrigation water in the transmission of resistant E. coli were studied. The presence of ESBL/AmpC, genetic similarity and phylogeny were typed using genotypic and phenotypic techniques. The frequency of β-lactamase gene transfer was studied in vitro. ESBLs/AmpC were detected in 35 isolates (76%). Fourteen isolates (30%) produced both ESBLs/AmpC. Prevalence was highest in E. coli from lettuce (90%). Twenty-two isolates (48%) were multi-resistant with between two and five ESBL/AmpC genes. The major ESBL determinant was the CTX-M type (34 isolates). DHA (33% of isolates) were the dominant AmpC β lactamases. There was a high conjugation efficiency among the isolates, ranging from 3.5 × 10−2 to 1 × 10−2 ± 1.4 × 10−1 transconjugants per recipient. Water isolates showed a significantly higher conjugation frequency than those from lettuce. A high degree of genetic relatedness between E. coli from irrigation water and lettuce indicated possible common ancestry and pathway of transmission. PMID:25488608

  7. Structural and optical study of core-shell InGaN layers of nanorod arrays with multiple stacks of InGaN/GaN superlattices for absorption of longer solar spectrum

    NASA Astrophysics Data System (ADS)

    Bae, Si-Young; Jung, Byung Oh; Lekhal, Kaddour; Lee, Dong-Seon; Deki, Manato; Honda, Yoshio; Amano, Hiroshi

    2016-05-01

    We report on the material and optical properties of core-shell InGaN layers grown on GaN nanorod arrays. The core-shell InGaN layers were well grown on polarization-reduced surfaces such as semipolar pyramids and nonpolar sidewalls. In addition, to compensate the biaxial strain between GaN and InGaN layers, we grew interlayers underneath a thick InGaN layer. Here, the interlayers were composed of multiple superlattice structures. We could observe that the indium composition of core-shell InGaN structures increased with the number of interlayers. This indicates that the absorption energy band of InGaN alloys can be better matched to the spectral irradiance of the solar spectrum in nature. We also implemented a simulation of Ga-polar and nonpolar InGaN-based solar cells based on the indium composition obtained from the experiments. The result showed that nonpolar InGaN solar cells had a much higher efficiency than Ga-polar InGaN solar cells with the same thickness of the absorption layer.

  8. The enhancement of 21.2%-power conversion efficiency in polymer photovoltaic cells by using mixed Au nanoparticles with a wide absorption spectrum of 400 nm-1000 nm

    NASA Astrophysics Data System (ADS)

    Hao, Jing-Yu; Xu, Ying; Zhang, Yu-Pei; Chen, Shu-Fen; Li, Xing-Ao; Wang, Lian-Hui; Huang, Wei

    2015-04-01

    Au nanoparticles (NPs) mixed with a majority of bone-like, rod, and cube shapes and a minority of irregular spheres, which can generate a wide absorption spectrum of 400 nm-1000 nm and three localized surface plasmon resonance peaks, respectively, at 525, 575, and 775 nm, are introduced into the hole extraction layer poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) to improve optical-to-electrical conversion performances in polymer photovoltaic cells. With the doping concentration of Au NPs optimized, the cell performance is significantly improved: the short-circuit current density and power conversion efficiency of the poly(3-hexylthiophene): [6,6]-phenyl-C60-butyric acid methyl ester cell are increased by 20.54% and 21.2%, reaching 11.15 mA·cm-2 and 4.23%. The variations of optical, electrical, and morphology with the incorporation of Au NPs in the cells are analyzed in detail, and our results demonstrate that the cell performance improvement can be attributed to a synergistic reaction, including: 1) both the localized surface plasmon resonance- and scattering-induced absorption enhancement of the active layer, 2) Au doping-induced hole transport/extraction ability enhancement, and 3) large interface roughness-induced efficient exciton dissociation and hole collection. Project supported by the National Basic Research Program of China (Grant Nos. 2015CB932202 and 2012CB933301), the National Natural Science Foundation of China (Grant Nos. 61274065, 51173081, 61136003, BZ2010043, 51372119, and 51172110), the Science Fund from the Ministry of Education of China (Grant No. IRT1148), the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20113223110005), the Priority Academic Program Development of Jiangsu Provincial Higher Education Institutions (Grant No. YX03001), and the National Synergistic Innovation Center for Advanced Materials and the Synergetic Innovation Center for Organic Electronics and

  9. Young Adults with Autism Spectrum Disorder Show Normal Attention to Eye-Gaze Information--Evidence from a New Change Blindness Paradigm

    ERIC Educational Resources Information Center

    Fletcher-Watson, Sue; Leekam, Susan R.; Findlay, John M.; Stanton, Elaine C.

    2008-01-01

    Other people's eye-gaze is a powerful social stimulus that captures and directs visual attention. There is evidence that this is not the case for children with autism spectrum disorder (ASD), although less is known about attention to eye-gaze in adults. We investigated whether young adults would detect a change to the direction of eye-gaze in…

  10. Infrared Attenuation Spectrum of Bulk High-Resistivity CdZnTe Single Crystal in Transparent Wavelength Region Between Electronic and Lattice Absorptions

    NASA Astrophysics Data System (ADS)

    Sarugaku, Yuki; Kaji, Sayumi; Ikeda, Yuji; Kobayashi, Naoto; Sukegawa, Takashi; Nakagawa, Takao; Kataza, Hirokazu; Kondo, Sohei; Yasui, Chikako; Nakanishi, Kenshi; Kawakita, Hideyo

    2016-09-01

    We report measurement of the internal attenuation coefficient, α _{att} , of a bulk high-resistivity cadmium zinc telluride (CdZnTe) single crystal at wavelength, λ = 0.84-26 μ m, to the unprecedentedly low level of α _{att} ˜ 0.001 cm^{-1} . This measurement reveals the spectral behavior for small attenuation in the infrared transparent region between the electronic and lattice absorptions. This result is essential for application of CdZnTe as an infrared transmitting material. Comparing the attenuation spectrum with model spectra obtained on the basis of Mie theory, we find that sub-micrometer-sized Te particles (inclusions) with a number density of approximately 10^{7.5-9} cm^{-3} are the principal source of the small attenuation observed at λ = 0.9-13 μ m. In addition, we determine α _{att} = (7.7 ± 1.9) × 10^{-4} cm^{-1} at λ = 10.6 μ m, which is valuable for CO_2 laser applications. Higher transparency can be achieved by reducing the number of inclusions rather than the number of precipitates. This study also demonstrates that high-accuracy measurement of CdZnTe infrared transmittance is a useful approach to investigating the number density of sub-micrometer-sized Te particles that cannot be identified via infrared microscopy.

  11. Titanium Dioxide/Upconversion Nanoparticles/Cadmium Sulfide Nanofibers Enable Enhanced Full-Spectrum Absorption for Superior Solar Light Driven Photocatalysis.

    PubMed

    Zhang, Fu; Zhang, Chuan-Ling; Wang, Wan-Ni; Cong, Huai-Ping; Qian, Hai-Sheng

    2016-06-22

    In this work, we demonstrate an electrospinning technique to fabricate TiO2 /upconversion nanoparticles (UCNPs)/CdS nanofibers on large scale. In addition, the as-prepared TiO2 nanofibers are incorporated with a high population of UCNPs and CdS nanospheres; this results in Förster resonance energy-transfer configurations of the UCNPs, TiO2 , and CdS nanospheres that are in close proximity. Hence, strong fluorescent emissions for the Tm(3+) ions including the (1) G4 →(3) H6 transition are efficiently transferred to TiO2 and the CdS nanoparticles through an energy-transfer process. The as-prepared TiO2 /UCNPs/CdS nanofibers exhibit full-spectrum solar-energy absorption and enable the efficient degradation of organic dyes by fluorescence resonance energy transfer between the UCNPs and TiO2 (or CdS). The UCNPs/TiO2 /CdS nanofibers may also have enhanced energy-transfer efficiency for wide applications in solar cells, bioimaging, photodynamics, and chemotherapy.

  12. Infrared absorption mechanisms of black silicon

    NASA Astrophysics Data System (ADS)

    Cheng, Zhengxi; Chen, Yongping; Ma, Bin

    2014-09-01

    Black silicon has a wide spectrum of non-spectral characteristics high absorption from visible to long wave infrared band .Based on semi-empirical impurity band model, free carrier absorption, radiation transitions between the valence band and the impurity band, radiation transitions between the impurity band and the conduction band were calculated, and absorption coefficients for each process were got. The results showed that the transitions from valence band to the impurity band induced absorption in the near-infrared waveband, but it has a rapid decay with wavelength. In the shortwave mid-wave and long-wave IR bands, transitions from the impurity band to the conduction band caused a huge absorption, and the absorption coefficient was slowly decreased with increasing wavelength. The free carrier absorption dominates in long-wave band. The calculation results agreed well with the test results of plant black silicon in magnitude and trends.

  13. The Complete Ultraviolet Spectrum of the Archetypal "Wind-dominated" Quasar Mrk 231: Absorption and Emission from a High-speed Dusty Nuclear Outflow

    NASA Astrophysics Data System (ADS)

    Veilleux, S.; Meléndez, M.; Tripp, T. M.; Hamann, F.; Rupke, D. S. N.

    2016-07-01

    New near- and far-ultraviolet (NUV and FUV) Hubble Space Telescope spectra of Mrk 231, the nearest quasar known, are combined with ground-based optical spectra to study the remarkable dichotomy between the FUV and NUV-optical spectral regions in this object. The FUV emission-line features are faint, broad, and highly blueshifted (up to ˜7000 km s-1), with no significant accompanying absorption. In contrast, the profiles of the NUV absorption features resemble those of the optical Na i D, He i, and Ca ii H and K lines, exhibiting broad blueshifted troughs that overlap in velocity space with the FUV emission-line features and indicate a dusty, high-density and patchy broad absorption line (BAL) screen covering ˜90% of the observed continuum source at a distance ≲2-20 pc. The FUV continuum emission does not show the presence of any obvious stellar features and is remarkably flat compared with the steeply declining NUV continuum. The NUV (FUV) features and continuum emission have not varied significantly over the past ˜22 (3) years and are unresolved on scales ˜40 (170) pc. These results favor an active galactic nucleus origin for the NUV-FUV line and continuum emission. The observed FUV line emission is produced in the outflowing BAL cloud system, while the Balmer lines arise primarily from the standard broad line region seen through the dusty BAL screen. Our data are inconsistent with the recently proposed binary black hole model. We argue instead that Mrk 231 is the nearest example of weak-lined “wind-dominated” quasars with high Eddington ratios and geometrically thick (“slim”) accretion disks; these quasars are likely more common in the early universe.

  14. X-ray absorption and resonant inelastic x-ray scattering (RIXS) show the presence of Cr{sup +} at the surface and in the bulk of CrF{sub 2}

    SciTech Connect

    Jiménez-Mier, J.; Olalde-Velasco, P.; Yang, W.-L.; Denlinger, J.

    2015-07-23

    X-Ray absorption and resonant inelastic x-ray scattering (RIXS) spectra of CrF{sub 2} recorded at the chromium L{sub 2,3} are presented. An atomic multiplet crystal field calculation is compared with the experimental data. Experiment and theory are in agreement once the calculation includes three chromium oxidation states, namely Cr{sup +}, Cr{sup 2+}, and Cr{sup 3+}. X-Ray absorption allows a direct determination of the surface oxidation, while the RIXS spectra shows the presence of these three oxidation states in the sample bulk. To give a quantitative interpretation of the RIXS data the effect of the incomming and outgoing photon penetration depth and self-absorption must be considered. For the much simpler case of MnF{sub 2}, with only one metal oxidation state, the measured RIXS spectra relative intensities are found to be proportional to the square of the sample attenuation length.

  15. Rhenium(I) tricarbonyl polypyridine complexes showing strong absorption of visible light and long-lived triplet excited states as a triplet photosensitizer for triplet-triplet annihilation upconversion.

    PubMed

    Yi, Xiuyu; Zhao, Jianzhang; Wu, Wanhua; Huang, Dandan; Ji, Shaomin; Sun, Jifu

    2012-08-01

    The preparation of rhenium(I) tricarbonyl polypyridine complexes that show a strong absorption of visible light and long-lived triplet excited state and the application of these complexes as triplet photosensitizers for triplet-triplet annihilation (TTA) based upconversion are reported. Imidazole-fused phenanthroline was used as the N^N coordination ligand, on which different aryl groups were attached (Phenyl, Re-0; Coumarin, Re-1 and naphthyl, Re-2). Re-1 shows strong absorption of visible light (ε = 60,800 M(-1) cm(-1) at 473 nm). Both Re-1 and Re-2 show long-lived T(1) states (lifetime, τ(T), is up to 86.0 μs and 64.0 μs, respectively). These properties are in contrast to the weak absorption of visible light and short-lived triplet excited states of the normal rhenium(I) tricarbonyl polypyridine complexes, such as Re-0 (ε = 5100 M(-1) cm(-1) at 439 nm, τ(T) = 2.2 μs). The photophysical properties of the complexes were fully studied with steady state and time-resolved absorption and emission spectroscopes, as well as DFT calculations. The intra-ligand triplet excited state is proposed to be responsible for the exceptionally long-lived T(1) states of Re-1 and Re-2. The Re(I) complexes were used as triplet photosensitizers for TTA based upconversion and an upconversion quantum yield up to 17.0% was observed.

  16. Transgenic Brassica rapa plants over-expressing eIF(iso)4E variants show broad-spectrum Turnip mosaic virus (TuMV) resistance.

    PubMed

    Kim, Jinhee; Kang, Won-Hee; Hwang, Jeena; Yang, Hee-Bum; Dosun, Kim; Oh, Chang-Sik; Kang, Byoung-Cheorl

    2014-08-01

    The protein-protein interaction between VPg (viral protein genome-linked) of potyviruses and eIF4E (eukaryotic initiation factor 4E) or eIF(iso)4E of their host plants is a critical step in determining viral virulence. In this study, we evaluated the approach of engineering broad-spectrum resistance in Chinese cabbage (Brassica rapa) to Turnip mosaic virus (TuMV), which is one of the most important potyviruses, by a systematic knowledge-based approach to interrupt the interaction between TuMV VPg and B. rapa eIF(iso)4E. The seven amino acids in the cap-binding pocket of eIF(iso)4E were selected on the basis of other previous results and comparison of protein models of cap-binding pockets, and mutated. Yeast two-hybrid assay and co-immunoprecipitation analysis demonstrated that W95L, K150L and W95L/K150E amino acid mutations of B. rapa eIF(iso)4E interrupted its interaction with TuMV VPg. All eIF(iso)4E mutants were able to complement an eIF4E-knockout yeast strain, indicating that the mutated eIF(iso)4E proteins retained their function as a translational initiation factor. To determine whether these mutations could confer resistance, eIF(iso)4E W95L, W95L/K150E and eIF(iso)4E wild-type were over-expressed in a susceptible Chinese cabbage cultivar. Evaluation of the TuMV resistance of T1 and T2 transformants demonstrated that the over-expression of the eIF(iso)4E mutant forms can confer resistance to multiple TuMV strains. These data demonstrate the utility of knowledge-based approaches for the engineering of broad-spectrum resistance in Chinese cabbage.

  17. Transgenic Brassica rapa plants over-expressing eIF(iso)4E variants show broad-spectrum Turnip mosaic virus (TuMV) resistance.

    PubMed

    Kim, Jinhee; Kang, Won-Hee; Hwang, Jeena; Yang, Hee-Bum; Dosun, Kim; Oh, Chang-Sik; Kang, Byoung-Cheorl

    2014-08-01

    The protein-protein interaction between VPg (viral protein genome-linked) of potyviruses and eIF4E (eukaryotic initiation factor 4E) or eIF(iso)4E of their host plants is a critical step in determining viral virulence. In this study, we evaluated the approach of engineering broad-spectrum resistance in Chinese cabbage (Brassica rapa) to Turnip mosaic virus (TuMV), which is one of the most important potyviruses, by a systematic knowledge-based approach to interrupt the interaction between TuMV VPg and B. rapa eIF(iso)4E. The seven amino acids in the cap-binding pocket of eIF(iso)4E were selected on the basis of other previous results and comparison of protein models of cap-binding pockets, and mutated. Yeast two-hybrid assay and co-immunoprecipitation analysis demonstrated that W95L, K150L and W95L/K150E amino acid mutations of B. rapa eIF(iso)4E interrupted its interaction with TuMV VPg. All eIF(iso)4E mutants were able to complement an eIF4E-knockout yeast strain, indicating that the mutated eIF(iso)4E proteins retained their function as a translational initiation factor. To determine whether these mutations could confer resistance, eIF(iso)4E W95L, W95L/K150E and eIF(iso)4E wild-type were over-expressed in a susceptible Chinese cabbage cultivar. Evaluation of the TuMV resistance of T1 and T2 transformants demonstrated that the over-expression of the eIF(iso)4E mutant forms can confer resistance to multiple TuMV strains. These data demonstrate the utility of knowledge-based approaches for the engineering of broad-spectrum resistance in Chinese cabbage. PMID:24417952

  18. On the Ammonia Absorption on Saturn

    NASA Astrophysics Data System (ADS)

    Tejfel, Victor G.; Karimov, A. M.; Lyssenko, P. G.; Kharitonova, G. A.

    2015-11-01

    The ammonia absorption bands centered at wavelengths of 645 and 787 nm in the visible spectrum of Saturn are very weak and overlapped with more strong absorption bands of methane. Therefore, the allocation of these bands is extremely difficult. In fact, the NH3 band 787 nm is completely masked by methane. The NH3 645 nm absorption band is superimposed on a relatively weak shortwave wing of CH4 band, in which the absorption maximum lies at the wavelength of 667 nm. In 2009, during the equinox on Saturn we have obtained the series of zonal spectrograms by scanning of the planet disk from the southern to the northern polar limb. Besides studies of latitudinal variation of the methane absorption bands we have done an attempt to trace the behavior of the absorption of ammonia in the band 645 nm. Simple selection of the pure NH3 profile of the band was not very reliable. Therefore, after normalizing to the ring spectrum and to the level of the continuous spectrum for entire band ranging from 630 to 680 nm in the equivalent widths were calculated for shortwave part of this band (630-652 nm), where the ammonia absorption is present, and a portion of the band CH4 652-680 nm. In any method of eliminating the weak part of the methane uptake in the short wing show an increased ammonia absorption in the northern hemisphere compared to the south. This same feature is observed also in the behavior of weak absorption bands of methane in contrast to the more powerful, such as CH4 725 and 787 nm. This is due to the conditions of absorption bands formation in the clouds at multiple scattering. Weak absorption bands of methane and ammonia are formed on the large effective optical depths and their behavior reflects the differences in the degree of uniformity of the aerosol component of the atmosphere of Saturn.

  19. Electric modulation of optical absorption in nanowires

    NASA Astrophysics Data System (ADS)

    Sakr, M. R.

    2016-11-01

    We have calculated the effect of an external electric field on the intersubband optical absorption of a nanowire subjected to a perpendicular magnetic field and Rashba effect. The absorption peaks due to optical transitions that are forbidden in the absence of the intersubband coupling experience strong amplitude modulation. This effect is quadratic in electric fields applied along the direction of quantum confinement or perpendicularly to tune the Rashba parameter. The electric field also induces frequency modulation in the associated spectrum. On the other hand, transitions that are normally allowed show, to a large extent, a parallel band effect, and accordingly they are responsible for strong optical absorption.

  20. Enhanced Hydrogen Evolution in the Presence of Plasmonic Au-Photo-Sensitized g-C3N4 with an Extended Absorption Spectrum from 460 to 640 nm.

    PubMed

    Xie, Lihong; Ai, Zhuyu; Zhang, Meng; Sun, Runze; Zhao, Weirong

    2016-01-01

    Extensively spectral-responsive photocatalytic hydrogen production was achieved over g-C3N4 photo-sensitized by Au nanoparticles. The photo-sensitization, which was achieved by a facile photo-assisted reduction route, resulted in an extended spectral range of absorption from 460 to 640 nm. The photo-sensitized g-C3N4 (Au/g-C3N4) photocatalysts exhibit significantly enhanced photocatalytic hydrogen evolution with a TOF value of 223 μmol g-1 h-1, which is a 130-fold improvement over g-C3N4. The hydrogen production result confirms that Au nanoparticles are effective photo-sensitizers for the visible light-responsive substrate g-C3N4. UV-vis diffuse reflection spectra (DRS), photoluminescence spectra (PL), electron spin resonance (ESR), and electrochemical measurements were used to investigate the transfer process of photogenerated electrons. The optimal Au/g-C3N4 photocatalyst displays the lowest charge transfer resistance of 18.45 Ω cm-2 and a high electron transfer efficiency, as determined by electrochemical impedance spectroscopy (EIS). The photo-sensitized g-C3N4 shows a broad range of response to visible light (400-640 nm), with significantly high incident photon-to-current efficiency (IPCE) values of 14.52%, 2.9%, and 0.74% under monochromatic light irradiation of 400, 550, and 640 nm, respectively. ESR characterization suggests that Au nanoparticles are able to absorb visible light of wavelengths higher than 460 nm and to generate hot electrons due to the SPR effect. PMID:27575246

  1. Enhanced Hydrogen Evolution in the Presence of Plasmonic Au-Photo-Sensitized g-C3N4 with an Extended Absorption Spectrum from 460 to 640 nm

    PubMed Central

    Xie, Lihong; Ai, Zhuyu; Zhang, Meng; Sun, Runze; Zhao, Weirong

    2016-01-01

    Extensively spectral-responsive photocatalytic hydrogen production was achieved over g-C3N4 photo-sensitized by Au nanoparticles. The photo-sensitization, which was achieved by a facile photo-assisted reduction route, resulted in an extended spectral range of absorption from 460 to 640 nm. The photo-sensitized g-C3N4 (Au/g-C3N4) photocatalysts exhibit significantly enhanced photocatalytic hydrogen evolution with a TOF value of 223 μmol g-1 h-1, which is a 130-fold improvement over g-C3N4. The hydrogen production result confirms that Au nanoparticles are effective photo-sensitizers for the visible light-responsive substrate g-C3N4. UV–vis diffuse reflection spectra (DRS), photoluminescence spectra (PL), electron spin resonance (ESR), and electrochemical measurements were used to investigate the transfer process of photogenerated electrons. The optimal Au/g-C3N4 photocatalyst displays the lowest charge transfer resistance of 18.45 Ω cm-2 and a high electron transfer efficiency, as determined by electrochemical impedance spectroscopy (EIS). The photo-sensitized g-C3N4 shows a broad range of response to visible light (400–640 nm), with significantly high incident photon-to-current efficiency (IPCE) values of 14.52%, 2.9%, and 0.74% under monochromatic light irradiation of 400, 550, and 640 nm, respectively. ESR characterization suggests that Au nanoparticles are able to absorb visible light of wavelengths higher than 460 nm and to generate hot electrons due to the SPR effect. PMID:27575246

  2. Enhanced Hydrogen Evolution in the Presence of Plasmonic Au-Photo-Sensitized g-C3N4 with an Extended Absorption Spectrum from 460 to 640 nm.

    PubMed

    Xie, Lihong; Ai, Zhuyu; Zhang, Meng; Sun, Runze; Zhao, Weirong

    2016-01-01

    Extensively spectral-responsive photocatalytic hydrogen production was achieved over g-C3N4 photo-sensitized by Au nanoparticles. The photo-sensitization, which was achieved by a facile photo-assisted reduction route, resulted in an extended spectral range of absorption from 460 to 640 nm. The photo-sensitized g-C3N4 (Au/g-C3N4) photocatalysts exhibit significantly enhanced photocatalytic hydrogen evolution with a TOF value of 223 μmol g-1 h-1, which is a 130-fold improvement over g-C3N4. The hydrogen production result confirms that Au nanoparticles are effective photo-sensitizers for the visible light-responsive substrate g-C3N4. UV-vis diffuse reflection spectra (DRS), photoluminescence spectra (PL), electron spin resonance (ESR), and electrochemical measurements were used to investigate the transfer process of photogenerated electrons. The optimal Au/g-C3N4 photocatalyst displays the lowest charge transfer resistance of 18.45 Ω cm-2 and a high electron transfer efficiency, as determined by electrochemical impedance spectroscopy (EIS). The photo-sensitized g-C3N4 shows a broad range of response to visible light (400-640 nm), with significantly high incident photon-to-current efficiency (IPCE) values of 14.52%, 2.9%, and 0.74% under monochromatic light irradiation of 400, 550, and 640 nm, respectively. ESR characterization suggests that Au nanoparticles are able to absorb visible light of wavelengths higher than 460 nm and to generate hot electrons due to the SPR effect.

  3. UV-vis absorption spectrum of a novel Ru(II) complex intercalated in DNA: [Ru(2,2'-bipy)(dppz)(2,2'-ArPy)]⁺.

    PubMed

    Chantzis, Agisilaos; Very, Thibaut; Despax, Stéphane; Issenhuth, Jean-Thomas; Boeglin, Alex; Hébraud, Pascal; Pfeffer, Michel; Monari, Antonio; Assfeld, Xavier

    2014-03-01

    The synthesis of a new Ru(II) complex is reported. Its absorption spectrum when interacting with DNA in water was calculated at the hybrid quantum mechanics molecular mechanics level of theory and compared with experimental data. The vertical transitions were computed using time-dependent density functional theory in the linear response approximation. The complex and its environment were treated at the quantum mechanical and molecular mechanical levels, respectively. The effects of the environment were investigated in detail and conveniently classified into electrostatic and polarization effects. The latter were modeled using the computationally inexpensive "electronic response of the surroundings" method. It was found that the main features of the experimental spectrum are nicely reproduced by the theoretical calculations. Moreover, analysis of the most intense transitions utilizing the natural transition orbital formalism revealed important insights into their nature and their potential role in the irreversible oxidation of DNA, a phenomenon that could be relevant in the field of cancer therapy.

  4. Broadband microwave absorption spectrometer for liquid media

    SciTech Connect

    Mukherjee, P.; Gosnell, T.R.; Bigio, I.J.

    1988-12-01

    A broadband, continuous-sweep microwave spectrometer has been constructed for measurements of the absorption coefficient of aqueous solutions and other liquid media. The spectrometer makes use of the phase fluctuation optical heterodyne technique, which provides a direct measure of the microwave power deposited in the sample. Consequently, in contrast to the standard dielectrometric techniques that indirectly determine the absorption coefficient via separate measurements of the real and imaginary parts of the dielectric constant, this spectrometer directly measures the microwave absorption coefficient. Broadband spectra are obtained using a transmission line to couple microwave power into the liquid sample. The absorption spectrum for deionized water in the range 3--20 GHz is presented as an example and shows excellent agreement with calculated values of the absorption coefficient based on previously published dielectric data.

  5. 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.

  6. Comparative study of the absorption spectrum of Li 2CaSiO 4:Cr 4+: First-principles fully relativistic and crystal field calculations

    NASA Astrophysics Data System (ADS)

    Brik, M. G.; Ogasawara, K.

    2007-11-01

    Systematic analysis of the energy level scheme and ground state absorption of the Cr4+ ion in Li2CaSiO4 crystal was performed using the exchange charge model of the crystal field [B.Z. Malkin, in: A.A. Kaplyanskii, B.M. Macfarlane (Eds.), Spectroscopy of Solids Containing Rare-earth Ions, North-Holland, Amsterdam, 1987, pp. 33-50] and recently developed first-principles approach to the analysis of the absorption spectra of impurity ions in crystals based on the discrete variational multielectron (DVME) method [K. Ogasawara, T. Iwata, Y. Koyama, T. Ishii, I. Tanaka, H. Adachi, Phys. Rev. B 64 (2001) 115413]. Using the former method, the values of parameters of crystal field acting on the Cr4+ ion valence electrons were calculated using the Li2CaSiO4 crystal structure data. Energy levels of the Cr4+ ion obtained after diagonalizing the crystal field Hamiltonian are in good agreement with those obtained from the experimental spectra. The latter method is based on the numerical solution of the Dirac equation; therefore, all relativistic effects are automatically considered. As a result, energy level scheme of Cr4+ and its absorption spectra in both polarizations were calculated, assigned and compared with experimental data; energy of the lowest charge transfer transition was evaluated and compared with theoretical predictions for the CrO44- complex available in the literature. The main features of the experimental spectra shape are reproduced well by the calculations. By performing analysis of the molecular orbitals (MO) population, it was shown that the covalent effects play an important role in formation of the spectral properties of Cr4+ ion in the considered crystal.

  7. Communication: THz absorption spectrum of the CO{sub 2}–H{sub 2}O complex: Observation and assignment of intermolecular van der Waals vibrations

    SciTech Connect

    Andersen, J.; Mahler, D. W.; Larsen, R. Wugt; Heimdal, J.; Nelander, B.

    2014-03-07

    Terahertz absorption spectra have been recorded for the weakly bound CO{sub 2}–H{sub 2}O complex embedded in cryogenic neon matrices at 2.8 K. The three high-frequency van der Waals vibrational transitions associated with out-of-plane wagging, in-plane rocking, and torsional motion of the isotopic H{sub 2}O subunit have been assigned and provide crucial observables for benchmark theoretical descriptions of this systems’ flat intermolecular potential energy surface. A (semi)-empirical value for the zero-point energy of 273 ± 15 cm{sup −1} from the class of intermolecular van der Waals vibrations is proposed and the combination with high-level quantum chemical calculations provides a value of 726 ± 15 cm{sup −1} for the dissociation energy D{sub 0}.

  8. Influence of the size and protonation state of acidic residue 85 on the absorption spectrum and photoreaction of the bacteriorhodopsin chromophore

    NASA Technical Reports Server (NTRS)

    Lanyi, J. K.; Tittor, J.; Varo, G.; Krippahl, G.; Oesterhelt, D.

    1992-01-01

    The consequences of replacing Asp-85 with glutamate in bacteriorhodopsin, as expressed in Halobacterium sp. GRB, were investigated. Similarly to the in vitro mutated and in Escherichia coli expressed protein, the chromophore was found to exist as a mixture of blue (absorption maximum 615 nm) and red (532 nm) forms, depending on the pH. However, we found two widely separated pKa values (about 5.4 and 10.4 without added salt), arguing for two blue and two red forms in separate equilibria. Both blue and red forms of the protein are in the two-dimensional crystalline state. A single pKa, such as in the E. coli expressed protein, was observed only after solubilization with detergent. The photocycle of the blue forms was determined at pH 4.0 with 610 nm photoexcitation, and that of the red forms at pH 10.5 and with 520 nm photoexcitation, in the time-range of 100 ns to 1 s. The blue forms produced no M, but a K- and an L-like intermediate, whose spectra and kinetics resembled those of blue wild-type bacteriorhodopsin below pH 3. The red forms produced a K-like intermediate, as well as M and N. Only the red forms transported protons. Specific perturbation of the neighborhood of the Schiff base by the replacement of Asp-85 with glutamate was suggested by (1) the shift and splitting of the pKa for what is presumably the protonation of residue 85, (2) a 36 nm blue-shift in the absorption of the all-trans red chromophore and a 25 nm red-shift of the 13-cis N chromophore, as compared to wild-type bacteriorhodopsin and its N intermediate, and (3) significant acceleration of the deprotonation of the Schiff base at pH 7, but not of its reprotonation and the following steps in the photocycle.

  9. THE 3-5 {mu}m SPECTRUM OF NGC 1068 AT HIGH ANGULAR RESOLUTION: DISTRIBUTION OF EMISSION AND ABSORPTION FEATURES ACROSS THE NUCLEAR CONTINUUM SOURCE

    SciTech Connect

    Geballe, T. R.; Mason, R. E.; Rodriguez-Ardila, A.; Axon, D. J.

    2009-08-20

    We report moderate resolution 3-5 {mu}m spectroscopy of the nucleus of NGC 1068 obtained at 0.''3 (20 pc) resolution with the spectrograph slit aligned approximately along the ionization cones of the active galactic nucleus. The deconvolved full width at half-maximum of the nuclear continuum source in this direction is 0.''3. Four coronal lines of widely different excitations were detected; the intensity of each peaks near radio knot C, approximately 0.''3 north of the infrared continuum peak, where the radio jet changes direction. Together with the broadened line profiles observed near that location, this suggests that shock ionization is the dominant excitation mechanism of the coronal lines. The depth of the 3.4 {mu}m hydrocarbon absorption is maximum at and just south of the continuum peak, similar to the 10 {mu}m silicate absorption. That and the similar and rapid variations of the optical depths of both features across the nucleus suggest that substantial portions of both arise in a dusty environment just in front of the continuum source(s). A new and tighter limit is set on the column density of CO. Although clumpy models of the dust screen might explain the shallowness of the silicate feature, the presence of the 3.4 {mu}m feature and the absence of CO are strongly reminiscent of Galactic diffuse cloud environments and a consistent explanation for them and the observed silicate feature is found if all three phenomena occur in such an environment, existing as close as 10 pc to the central engine.

  10. UV nebular absorption in Eta Car and Weigelt D

    NASA Astrophysics Data System (ADS)

    Nielsen, K. E.; Vieira, G. L.; Gull, T. R.; Lindler, D. J.; Eta Car HST Treasury Team

    2003-12-01

    The high angular and high spectral resolution of the HST/STIS MAMA echelle mode, provide an unique means to distinguish the physical structures surrounding Eta Car. Observations are parts of the HST treasury program (K. Davidson P.I.) for monitoring variations over Eta Car's spectroscopic minimum. Nebular emission is present above and below the stellar spectrum which is about 0.03'' wide. We have extracted the nebular part of the central source spectrum and compared it with the spectrum of Weigelt D, located approximately 0.2'' Northwest of the central source. The spectra show significant similarities and our conclusions are two-fold. First, the radiation from the Wiegelt blobs give an unwanted contribution to the spectrum of the central source, which emphasizes the importance of using an extracted spectrum in a spectral analysis. Second, the Weigelt blobs have so far been assumed to produce a pure emission line spectrum. However, this comparison shows the presence of similar absorption structures previously observed in the spectrum of the central star (Gull et al., 2003, submitted ApJL). Two velocity structures at approximately -50 and -500 km/s, respectively, have been observed in the Weigelt D spectrum. We present identifications of the absorption structures to supplement the emission line work performed by T. Zethson (2000, PhD Thesis) and provide additional information regarding the geometry of the inner parts of the Eta Car nebula. The -50 km/s velocity component is similar to the absorption structure at -146 km/s observed in the spectrum of the central object. If these velocity systems are related, this implies that the absorption component is located close to the central parts of the nebular system.

  11. Direction dependence of the magneto-optical absorption in nanowires with Rashba interaction

    NASA Astrophysics Data System (ADS)

    Sakr, M. R.

    2016-09-01

    We study the directional dependence of the absorption spectrum of ballistic nanowires in the presence of gate-controlled Rashba spin-orbit interaction and an in-plane magnetic field. In the weak Rashba regime, our analytical and numerical results show that the absorption peaks associated with the first and third intersubband transitions exhibit frequency shifts and strong amplitude modulations as the direction of the magnetic field changes. If the field is parallel to the nanowire axis, these peaks disappear and the resonance frequencies of the whole absorption spectrum are given merely in terms of the Zeeman splitting and the energy scale characterizing the confinement potential. The second transition has an absorption peak that suffers an opposite frequency shift with amplitude that is largely direction independent. The amplitude modulation and frequency shift of the absorption spectrum is periodic in the angle that the magnetic field makes with the nanowire axis.

  12. ANOMALOUS DIFFUSE INTERSTELLAR BANDS IN THE SPECTRUM OF HERSCHEL 36. I. OBSERVATIONS OF ROTATIONALLY EXCITED CH AND CH{sup +} ABSORPTION AND STRONG, EXTENDED REDWARD WINGS ON SEVERAL DIBs

    SciTech Connect

    Dahlstrom, Julie; York, Donald G.; Welty, Daniel E.; Oka, Takeshi; Johnson, Sean; Jiang Zihao; Sherman, Reid; Hobbs, L. M.; Friedman, Scott D.; Sonnentrucker, Paule; Rachford, Brian L.; Snow, Theodore P.

    2013-08-10

    Anomalously broad diffuse interstellar bands (DIBs) at 5780.5, 5797.1, 6196.0, and 6613.6 A are found in absorption along the line of sight to Herschel 36, the star illuminating the bright Hourglass region of the H II region Messier 8. Interstellar absorption from excited CH{sup +} in the J = 1 level and from excited CH in the J = 3/2 level is also seen. To our knowledge, neither those excited molecular lines nor such strongly extended DIBs have previously been seen in absorption from interstellar gas. These unusual features appear to arise in a small region near Herschel 36 which contains most of the neutral interstellar material in the sight line. The CH{sup +} and CH in that region are radiatively excited by strong far-IR radiation from the adjacent infrared source Her 36 SE. Similarly, the broadening of the DIBs toward Herschel 36 may be due to radiative pumping of closely spaced high-J rotational levels of relatively small, polar carrier molecules. If this picture of excited rotational states for the DIB carriers is correct and applicable to most DIBs, the 2.7 K cosmic microwave background may set the minimum widths (about 0.35 A) of known DIBs, with molecular processes and/or local radiation fields producing the larger widths found for the broader DIBs. Despite the intense local UV radiation field within the cluster NGC 6530, no previously undetected DIBs stronger than 10 mA in equivalent width are found in the optical spectrum of Herschel 36, suggesting that neither dissociation nor ionization of the carriers of the known DIBs by this intense field creates new carriers with easily detectable DIB-like features. Possibly related profile anomalies for several other DIBs are noted.

  13. Two-photon solvatochromism II: experimental and theoretical study of solvent effects on the two-photon absorption spectrum of Reichardt's dye.

    PubMed

    Wielgus, Małgorzata; Zaleśny, Robert; Murugan, N Arul; Kongsted, Jacob; Ågren, Hans; Samoc, Marek; Bartkowiak, Wojciech

    2013-11-11

    In this study, we report on the influence of solvent on the two-photon absorption (2PA) spectra of Reichardt's dye (RD). The measurement of 2PA cross-sections is performed for three solvents (chloroform, dimethyl formamide, and dimethyl sulfoxide) using the Z-scan technique. The key finding of this study is the observation that the cross-section, corresponding to the 2PA of the intramolecular charge-transfer state, diminishes substantially upon increasing the solvent polarity. To unravel the solvent dependence of the 2PA cross-section, the electronic structure of RD is determined using a hybrid quantum mechanics/molecular mechanics (QM/MM) approach, in which polarization between the solute and solvent is taken into account by using a self-consistent scheme in the solvent polarization. The two-state approximation proves to be adequate for the studied system, and allowed the observed solvent-polarity-induced decrease of the 2PA cross-section to be related to the decrease of the transition moment and the increase in the excitation energy. PMID:24106066

  14. [PHOSPHOLIPIDS AND FATTY ACIDS IN ERYTHROCYTES OF THE LAMPREY LAMPETRA FLUVIATILIS DURING AUTUMN PRESPAWNING PERIOD AND THE ABSORPTION SPECTRUM OF THEIR LIPID EXTRACT].

    PubMed

    Zabelinskii, S A; Chebotareva, M A; Shukolyukova, E P; Krivchenko, A I

    2015-01-01

    The content of some classes of phospholipids and their fatty acid composition in erythrocytes of the lamprey Lampetrafluviatilis during the autumn period of its prespawning migration are investigated. It is found that the phospholipid spectrum of erythrocytes of the lamprey, the oldest representative of vertebrates, is similar to that of many mammals. A four-fold prevalence of phosphatidilcholine content over sphingomyelin content as well as prevalence of (ω3-acids over ω6-acids indicates the of lamprey's erythrocyte membranes - an important indicator of deformational ability of lamprey's erythrocytes. Phosphatidilethanol amine and its plasmalogenic form are the most unsaturated phospholipids (their unsaturation indices are 230 and 342, correspondingly). Phosphatidilcholine is the most saturated one (UI is 167). It is found that the basic acid indicators characterizing the fluidity of erythrocyte membranes remain unchanged during the whole period of prespawning migration of lampreys up to spawning. The blood contains several buffer systems, in particular, membrane phospholipids which neutralize acids and alkali incoming into the blood. In the process of organism life a change of pH inside erythrocytes occurs. One can suppose that the base of the system associated with buffer properties of the blood is water dissociation. Inside thin vessels of the circulatory system the hemoglobin attaches and returns molecules of oxygen due to interaction of the buffer systems with water. The property of water to dissociate as well as ion transfer produce in erythrocytes, lying within narrow vessels of the circulatory system, a local pH alteration allowing displacing/attaching the molecule of oxygen from hemoglobin.

  15. "The Show"

    ERIC Educational Resources Information Center

    Gehring, John

    2004-01-01

    For the past 16 years, the blue-collar city of Huntington, West Virginia, has rolled out the red carpet to welcome young wrestlers and their families as old friends. They have come to town chasing the same dream for a spot in what many of them call "The Show". For three days, under the lights of an arena packed with 5,000 fans, the state's best…

  16. Dust in MG II Absorption Systems

    NASA Astrophysics Data System (ADS)

    Malhotra, S.

    The dust absorption feature at 2175 AA is detected in a composite spectrum of Mg II absorbers. The composite absorber spectrum is obtained by taking the geometric mean of 92 quasar spectra after aligning them in the rest-frame of 96 absorbers. By aligning the spectra according to absorber redshifts we reinforce the spectral features of the absorbers, and smooth over possible bumps and wiggles in the emission spectra. The width of the observed absorption feature is 200-300 AA (FWHM), or 0.4-0.6 microns^{-1} and the central wavelength is 2240 AA. The Galactic dust feature has a central wavelength of 2176 AA and FWHM = 0.8-1.25 microns^{-1}. Simulations show that this discrepancy between the properties of the 2175 AA feature in Mg II absorbers and Galactic ISM can be mostly explained by the different methods used to measure them (cf. Malhotra 1997).

  17. Scavenging and characterization of short-lived radicals using a novel stable nitroxide radical with a characteristic UV-vis absorption spectrum.

    PubMed

    Toba, Ryuta; Gotoh, Hiroaki; Sakakibara, Kazuhisa

    2014-08-01

    A stable tert-butyl(10-phenyl-9-anthryl)nitroxide (BPAN) radical was newly synthesized and used for the capture/characterization of reactive radicals. Adducts obtained from the reactions of BPAN with in situ generated reactive radicals showed excellent stability, assuring complete isolation and purification. The structures of the adducts were established by LC-MS and NMR analyses.

  18. Stellar Spectrum Synthesizer

    ERIC Educational Resources Information Center

    Landegren, G. F.

    1975-01-01

    Describes a device which employs two diffraction gratings and three or four simple lenses to produce arbitrary absorption or emission spectra that may be doppler shifted and spectroscopically examined by students some distance away. It may be regarded as a sort of artificial star whose spectrum may be analyzed as an undergraduate laboratory…

  19. K- and L-edge X-ray absorption spectrum calculations of closed-shell carbon, silicon, germanium, and sulfur compounds using damped four-component density functional response theory.

    PubMed

    Fransson, Thomas; Burdakova, Daria; Norman, Patrick

    2016-05-21

    X-ray absorption spectra of carbon, silicon, germanium, and sulfur compounds have been investigated by means of damped four-component density functional response theory. It is demonstrated that a reliable description of relativistic effects is obtained at both K- and L-edges. Notably, an excellent agreement with experimental results is obtained for L2,3-spectra-with spin-orbit effects well accounted for-also in cases when the experimental intensity ratio deviates from the statistical one of 2 : 1. The theoretical results are consistent with calculations using standard response theory as well as recently reported real-time propagation methods in time-dependent density functional theory, and the virtues of different approaches are discussed. As compared to silane and silicon tetrachloride, an anomalous error in the absolute energy is reported for the L2,3-spectrum of silicon tetrafluoride, amounting to an additional spectral shift of ∼1 eV. This anomaly is also observed for other exchange-correlation functionals, but it is seen neither at other silicon edges nor at the carbon K-edge of fluorine derivatives of ethene. Considering the series of molecules SiH4-XFX with X = 1, 2, 3, 4, a gradual divergence from interpolated experimental ionization potentials is observed at the level of Kohn-Sham density functional theory (DFT), and to a smaller extent with the use of Hartree-Fock. This anomalous error is thus attributed partly to difficulties in correctly emulating the electronic structure effects imposed by the very electronegative fluorines, and partly due to inconsistencies in the spurious electron self-repulsion in DFT. Substitution with one, or possibly two, fluorine atoms is estimated to yield small enough errors to allow for reliable interpretations and predictions of L2,3-spectra of more complex and extended silicon-based systems. PMID:27136720

  20. K- and L-edge X-ray absorption spectrum calculations of closed-shell carbon, silicon, germanium, and sulfur compounds using damped four-component density functional response theory.

    PubMed

    Fransson, Thomas; Burdakova, Daria; Norman, Patrick

    2016-05-21

    X-ray absorption spectra of carbon, silicon, germanium, and sulfur compounds have been investigated by means of damped four-component density functional response theory. It is demonstrated that a reliable description of relativistic effects is obtained at both K- and L-edges. Notably, an excellent agreement with experimental results is obtained for L2,3-spectra-with spin-orbit effects well accounted for-also in cases when the experimental intensity ratio deviates from the statistical one of 2 : 1. The theoretical results are consistent with calculations using standard response theory as well as recently reported real-time propagation methods in time-dependent density functional theory, and the virtues of different approaches are discussed. As compared to silane and silicon tetrachloride, an anomalous error in the absolute energy is reported for the L2,3-spectrum of silicon tetrafluoride, amounting to an additional spectral shift of ∼1 eV. This anomaly is also observed for other exchange-correlation functionals, but it is seen neither at other silicon edges nor at the carbon K-edge of fluorine derivatives of ethene. Considering the series of molecules SiH4-XFX with X = 1, 2, 3, 4, a gradual divergence from interpolated experimental ionization potentials is observed at the level of Kohn-Sham density functional theory (DFT), and to a smaller extent with the use of Hartree-Fock. This anomalous error is thus attributed partly to difficulties in correctly emulating the electronic structure effects imposed by the very electronegative fluorines, and partly due to inconsistencies in the spurious electron self-repulsion in DFT. Substitution with one, or possibly two, fluorine atoms is estimated to yield small enough errors to allow for reliable interpretations and predictions of L2,3-spectra of more complex and extended silicon-based systems.

  1. Effects of salts on thermolysin: activation of hydrolysis and synthesis of N-carbobenzoxy-L-aspartyl-L-phenylalanine methyl ester, and a unique change in the absorption spectrum of thermolysin.

    PubMed

    Inouye, K

    1992-09-01

    It has been reported that neutral salts such as NaCl activate the thermolysin-catalyzed hydrolysis of substrates containing glycine at the P1 position (carboxylic side of the cleavage bond) [Holmquist, B. & Vallee, B.L. (1976) Biochemistry 15, 101-107]. In this paper, we demonstrate that high concentrations (1-4 M) of neutral salts greatly enhance the thermolysin activity in both hydrolysis and synthesis of N-carbobenzoxy-L-aspartyl-L-phenylalanine methyl ester (ZAPM), a precursor of a peptide sweetener, aspartame, in which the L-aspartyl residue is the P1 residue. The enzyme activity is enhanced with an increase in salt concentration in a pseudo-exponential fashion. The degree of activation by salts was in the order LiCl > NaCl > KCl. The rate of ZAPM hydrolysis in the presence of 3.8 M NaCl was 6-7 times higher than that in its absence, and 50 times or more activation is expected in saturated NaCl solution. The activation is brought about solely through an increase in the catalytic constant (kcat), and the Michaelis constant (Km) is not affected at all by the presence of NaCl. On mixing thermolysin with NaCl, a unique absorption difference spectrum suggesting a conformational change of the enzyme was observed. The intensity increased in a pseudo-exponential fashion with increase of NaCl concentration up to 3 M, and this dependence is similar to that of the enzyme activity.

  2. VARIATIONS OF ABSORPTION TROUGHS IN THE QUASAR SDSS J125216.58+052737.7

    SciTech Connect

    Chen, Zhi-Fu; Qin, Yi-Ping

    2015-01-20

    In this work, we analyze the spectra of quasar J125216.58+052737.7 (z {sub em} = 1.9035) which was observed by SDSS-I/II on 2003 January 30 and by BOSS on 2011 April 2. Both the continuum and the absorption spectra of this quasar show obvious variations between the two epochs. In the SDSS-I/II spectrum, we detect 8 C IV λλ1548,1551 absorption systems, which are detected at z {sub abs} = 1.9098, 1.8948, 1.8841, 1.8770, 1.8732, 1.8635, 1.8154, and 1.7359, respectively, and one Mg II λλ2796,2803 absorption system at z {sub abs} = 0.9912. Among these absorption systems, two C IV λλ1548,1551 absorption systems at z {sub abs} = 1.9098 and 1.7359 and the Mg II λλ2796,2803 absorption system are imprinted on the BOSS spectrum as well, and have similar absorption strengths when compared to those measured from the SDSS-I/II spectrum. Three C IV λλ1548,1551 absorption systems at z {sub abs} = 1.8948, 1.8841, and 1.8770 are also detected in the BOSS spectrum, while their absorption strengths are much weaker than those measured from the SDSS-I/II spectrum; three systems at z {sub abs} = 1.8732, 1.8635, and 1.8154 disappeared from the BOSS spectrum. Based on the variability analysis, the absorption systems that disappeared and weakened are likely to be intrinsic to the quasar. If these intrinsic absorption gases are blown away from the central region of the quasar, with respect to the quasar system, the absorption systems that disappeared would have separation velocities of 3147 kms{sup –1}, 4161 km s{sup –1}, and 9241 km s{sup –1}, while the absorption systems that weakened would have separation velocities of 900 km s{sup –1}, 2011 km s{sup –1}, and 2751 km s{sup –1}. Well-coordinated variations of the six C IV λλ1548,1551 absorption systems that disappeared and weakened, occurring on a timescale of 1026.7 days at the quasar rest frame, can be interpreted as a result of global changes in the ionization state of the absorbing gas.

  3. Quantum Spread Spectrum Communication

    SciTech Connect

    Humble, Travis S

    2011-01-01

    We show that communication of single-photon quantum states in a multi-user environment is improved by using spread spectrum communication techniques. We describe a framework for spreading, transmitting, despreading, and detecting single-photon spectral states that mimics conventional spread spectrum techniques. We show in the cases of inadvertent detection, unintentional interference, and multi-user management, that quantum spread spectrum communications may minimize receiver errors by managing quantum channel access.

  4. Spectral properties of microwave graphs with local absorption.

    PubMed

    Allgaier, Markus; Gehler, Stefan; Barkhofen, Sonja; Stöckmann, H-J; Kuhl, Ulrich

    2014-02-01

    The influence of absorption on the spectra of microwave graphs has been studied experimentally. The microwave networks were made up of coaxial cables and T junctions. First, absorption was introduced by attaching a 50Ω load to an additional vertex for graphs with and without time-reversal symmetry. The resulting level-spacing distributions were compared with a generalization of the Wigner surmise in the presence of open channels proposed recently by Poli et al. [Phys. Rev. Lett. 108, 174101 (2012)]. Good agreement was found using an effective coupling parameter. Second, absorption was introduced along one individual bond via a variable microwave attenuator, and the influence of absorption on the length spectrum was studied. The peak heights in the length spectra corresponding to orbits avoiding the absorber were found to be independent of the attenuation, whereas, the heights of the peaks belonging to orbits passing the absorber once or twice showed the expected decrease with increasing attenuation.

  5. Zellweger Spectrum

    MedlinePlus

    ... the Zellweger spectrum result from defects in the assembly of a cellular structure called the peroxisome, and ... Zellweger spectrum are caused by defects in the assembly of the peroxisome. There are at least 12 ...

  6. DISCOVERY OF THE TRANSITION OF A MINI-BROAD ABSORPTION LINE INTO A BROAD ABSORPTION LINE IN THE SDSS QUASAR J115122.14+020426.3

    SciTech Connect

    Hidalgo, Paola Rodriguez; Eracleous, Michael; Charlton, Jane; Hamann, Fred; Murphy, Michael T.; Nestor, Daniel

    2013-09-20

    We present the detection of a rare case of dramatic strengthening in the UV absorption profiles in the spectrum of the quasar J115122.14+020426.3 between observations {approx}2.86 yr apart in the quasar rest frame. A spectrum obtained in 2001 by the Sloan Digital Sky Survey shows a C IV ''mini-broad'' absorption line (FWHM = 1220 km s{sup -1}) with a maximum blueshift velocity of {approx}9520 km s{sup -1}, while a later spectrum from the Very Large Telescope shows a significantly broader and stronger absorption line, with a maximum blueshift velocity of {approx}12, 240 km s{sup -1} that qualifies as a broad absorption line. A similar variability pattern is observed in two additional systems at lower blueshifted velocities and in the Ly{alpha} and N V transitions as well. One of the absorption systems appears to be resolved and shows evidence for partial covering of the quasar continuum source (C{sub f} {approx} 0.65), indicating a transverse absorber size of, at least, {approx}6 Multiplication-Sign 10{sup 16} cm. In contrast, a cluster of narrower C IV lines appears to originate in gas that fully covers the continuum and broad emission line sources. There is no evidence for changes in the centroid velocity of the absorption troughs. This case suggests that at least some of the absorbers that produce ''mini-broad'' and broad absorption lines in quasar spectra do not belong to intrinsically separate classes. Here, the ''mini-broad'' absorption line is most likely interpreted as an intermediate phase before the appearance of a broad absorption line due to their similar velocities. While the current observations do not provide enough constraints to discern among the possible causes for this variability, future monitoring of multiple transitions at high resolution will help achieve this goal.

  7. TURBULENCE SPECTRA FROM DOPPLER-BROADENED SPECTRAL LINES: TESTS OF THE VELOCITY CHANNEL ANALYSIS AND VELOCITY COORDINATE SPECTRUM TECHNIQUES

    SciTech Connect

    Chepurnov, A.; Lazarian, A.

    2009-03-10

    Turbulent motions induce Doppler shifts of observable emission and absorption lines motivating studies of turbulence using precision spectroscopy. We provide numerical testing of the two most promising techniques, velocity channel analysis and velocity coordinate spectrum (VCS). We obtain an expression for the shot noise that the discretization of the numerical data entails and successfully test it. We show that the numerical resolution required for recovering the underlying turbulent spectrum from observations depend on the spectral index of velocity fluctuations, which makes low-resolution testing misleading. We demonstrate numerically that, when dealing with absorption lines, sampling of turbulence along just a dozen directions provides a high quality spectrum with the VCS technique.

  8. Fission Spectrum

    DOE R&D Accomplishments Database

    Bloch, F.; Staub, H.

    1943-08-18

    Measurements of the spectrum of the fission neutrons of 25 are described, in which the energy of the neutrons is determined from the ionization produced by individual hydrogen recoils. The slow neutrons producing fission are obtained by slowing down the fast neutrons from the Be-D reaction of the Stanford cyclotron. In order to distinguish between fission neutrons and the remaining fast cyclotron neutrons both the cyclotron current and the pusle amplifier are modulated. A hollow neutron container, in which slow neutrons have a lifetime of about 2 milliseconds, avoids the use of large distances. This method results in much higher intensities than the usual modulation arrangement. The results show a continuous distribution of neutrons with a rather wide maximum at about 0.8 MV falling off to half of its maximum value at 2.0 MV. The total number of netrons is determined by comparison with the number of fission fragments. The result seems to indicate that only about 30% of the neutrons have energies below .8 MV. Various tests are described which were performed in order to rule out modification of the spectrum by inelastic scattering. Decl. May 4, 1951

  9. ABSORPTION MEASURE DISTRIBUTION IN Mrk 509

    SciTech Connect

    Adhikari, T. P.; Różańska, A.; Sobolewska, M.; Czerny, B.

    2015-12-20

    In this paper we model the observed absorption measure distribution (AMD) in Mrk 509, which spans three orders of magnitude in ionization level with a single-zone absorber in pressure equilibrium. AMD is usually constructed from observations of narrow absorption lines in radio-quiet active galaxies with warm absorbers. We study the properties of the warm absorber in Mrk 509 using recently published broadband spectral energy distribution observed with different instruments. This spectrum is an input in radiative transfer computations with full photoionization treatment using the titan code. We show that the simplest way to fully reproduce the shape of AMD is to assume that the warm absorber is a single zone under constant total pressure. With this assumption, we found theoretical AMD that matches the observed AMD determined on the basis of the 600 ks reflection grating spectrometer XMM-Newton spectrum of Mrk 509. The softness of the source spectrum and the important role of the free–free emission breaks the usual degeneracy in the ionization state calculations, and the explicit dependence of the depths of AMD dips on density open a new path to the density diagnostic for the warm absorber. In Mrk 509, the implied density is of the order of 10{sup 8} cm{sup −3}.

  10. A patient showing features of both SBBYSS and GPS supports the concept of a KAT6B-related disease spectrum, with mutations in mid-exon 18 possibly leading to combined phenotypes.

    PubMed

    Vlckova, Marketa; Simandlova, Martina; Zimmermann, Pavel; Stranecky, Viktor; Hartmannova, Hana; Hodanova, Katerina; Havlovicova, Marketa; Hancarova, Miroslava; Kmoch, Stanislav; Sedlacek, Zdenek

    2015-10-01

    Genitopatellar syndrome (GPS) and Say-Barber-Biesecker-Young-Simpson syndrome (SBBYSS) are two distinct clinically overlapping syndromes caused by de novo heterozygous truncating mutations in the KAT6B gene encoding lysine acetyltransferase 6B, a part of the histone H3 acetyltransferase complex. We describe an 8-year-old girl with a KAT6B mutation and a combined GPS/SBBYSS phenotype. The comparison of this patient with 61 previously published cases with KAT6B mutations and GPS, SBBYSS or combined GPS/SBBYSS phenotypes allowed us to separate the KAT6B mutations into four groups according to their position in the gene (reflecting nonsense mediated RNA decay and protein domains) and their clinical outcome. We suggest that mutations in mid-exon 18 corresponding to the C-terminal end of the acidic (Asp/Glu-rich) domain of KAT6B may have more variable expressivity leading to GPS, SBBYSS or combined phenotypes, in contrast to defects in other regions of the gene which contribute more specifically to either GPS or SBBYSS. Notwithstanding the clinical overlap, our cluster analysis of phenotypes of all known patients with KAT6B mutations supports the existence of two clinical entities, GPS and SBBYSS, as poles within the KAT6B-related disease spectrum. The awareness of these phenomena is important for qualified genetic counselling of patients with KAT6B mutations.

  11. A patient showing features of both SBBYSS and GPS supports the concept of a KAT6B-related disease spectrum, with mutations in mid-exon 18 possibly leading to combined phenotypes.

    PubMed

    Vlckova, Marketa; Simandlova, Martina; Zimmermann, Pavel; Stranecky, Viktor; Hartmannova, Hana; Hodanova, Katerina; Havlovicova, Marketa; Hancarova, Miroslava; Kmoch, Stanislav; Sedlacek, Zdenek

    2015-10-01

    Genitopatellar syndrome (GPS) and Say-Barber-Biesecker-Young-Simpson syndrome (SBBYSS) are two distinct clinically overlapping syndromes caused by de novo heterozygous truncating mutations in the KAT6B gene encoding lysine acetyltransferase 6B, a part of the histone H3 acetyltransferase complex. We describe an 8-year-old girl with a KAT6B mutation and a combined GPS/SBBYSS phenotype. The comparison of this patient with 61 previously published cases with KAT6B mutations and GPS, SBBYSS or combined GPS/SBBYSS phenotypes allowed us to separate the KAT6B mutations into four groups according to their position in the gene (reflecting nonsense mediated RNA decay and protein domains) and their clinical outcome. We suggest that mutations in mid-exon 18 corresponding to the C-terminal end of the acidic (Asp/Glu-rich) domain of KAT6B may have more variable expressivity leading to GPS, SBBYSS or combined phenotypes, in contrast to defects in other regions of the gene which contribute more specifically to either GPS or SBBYSS. Notwithstanding the clinical overlap, our cluster analysis of phenotypes of all known patients with KAT6B mutations supports the existence of two clinical entities, GPS and SBBYSS, as poles within the KAT6B-related disease spectrum. The awareness of these phenomena is important for qualified genetic counselling of patients with KAT6B mutations. PMID:26370006

  12. 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…

  13. 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.

  14. Resonant Nanophotonic Spectrum Splitting for Ultrathin Multijunction Solar Cells

    PubMed Central

    2015-01-01

    We present an approach to spectrum splitting for photovoltaics that utilizes the resonant optical properties of nanostructures for simultaneous voltage enhancement and spatial separation of different colors of light. Using metal–insulator–metal resonators commonly used in broadband metamaterial absorbers we show theoretically that output voltages can be enhanced significantly compared to single-junction devices. However, the approach is general and works for any type of resonator with a large absorption cross section. Due to its resonant nature, the spectrum splitting occurs within only a fraction of the wavelength, as opposed to traditional spectrum splitting methods, where many wavelengths are required. Combining nanophotonic spectrum splitting with other nanophotonic approaches to voltage enhancements, such as angle restriction and concentration, may lead to highly efficient but deeply subwavelength photovoltaic devices. PMID:26322319

  15. Economic strategies of plant absorptive roots vary with root diameter

    NASA Astrophysics Data System (ADS)

    Kong, D. L.; Wang, J. J.; Kardol, P.; Wu, H. F.; Zeng, H.; Deng, X. B.; Deng, Y.

    2016-01-01

    Plant roots typically vary along a dominant ecological axis, the root economics spectrum, depicting a tradeoff between resource acquisition and conservation. For absorptive roots, which are mainly responsible for resource acquisition, we hypothesized that root economic strategies differ with increasing root diameter. To test this hypothesis, we used seven plant species (a fern, a conifer, and five angiosperms from south China) for which we separated absorptive roots into two categories: thin roots (thickness of root cortex plus epidermis < 247 µm) and thick roots. For each category, we analyzed a range of root traits related to resource acquisition and conservation, including root tissue density, different carbon (C), and nitrogen (N) fractions (i.e., extractive, acid-soluble, and acid-insoluble fractions) as well as root anatomical traits. The results showed significant relationships among root traits indicating an acquisition-conservation tradeoff for thin absorptive roots while no such trait relationships were found for thick absorptive roots. Similar results were found when reanalyzing data of a previous study including 96 plant species. The contrasting economic strategies between thin and thick absorptive roots, as revealed here, may provide a new perspective on our understanding of the root economics spectrum.

  16. On the role of spatial position of bridged oxygen atoms as surface passivants on the ground-state gap and photo-absorption spectrum of silicon nano-crystals

    SciTech Connect

    Nazemi, Sanaz; Soleimani, Ebrahim Asl; Pourfath, Mahdi E-mail: pourfath@iue.tuwien.ac.at

    2015-11-28

    Silicon nano-crystals (NCs) are potential candidates for enhancing and tuning optical properties of silicon for optoelectronic and photo-voltaic applications. Due to the high surface-to-volume ratio, however, optical properties of NC result from the interplay of quantum confinement and surface effects. In this work, we show that both the spatial position of surface terminants and their relative positions have strong effects on NC properties as well. This is accomplished by investigating the ground-state HOMO-LUMO band-gap, the photo-absorption spectra, and the localization and overlap of HOMO and LUMO orbital densities for prototype ∼1.2 nm Si{sub 32–x}H{sub 42–2x}O{sub x} hydrogenated silicon NC with bridged oxygen atoms as surface terminations. It is demonstrated that the surface passivation geometry significantly alters the localization center and thus the overlap of frontier molecular orbitals, which correspondingly modifies the electronic and optical properties of NC.

  17. A SURVEY OF ALKALI LINE ABSORPTION IN EXOPLANETARY ATMOSPHERES

    SciTech Connect

    Jensen, Adam G.; Redfield, Seth; Endl, Michael; Cochran, William D.; Koesterke, Lars; Barman, Travis S. E-mail: sredfield@wesleyan.edu E-mail: wdc@astro.as.utexas.edu E-mail: barman@lowell.edu

    2011-12-20

    We obtained over 90 hr of spectroscopic observations of four exoplanetary systems with the Hobby-Eberly Telescope. Observations were taken in transit and out of transit, and we analyzed the differenced spectra-i.e., the transmission spectra-to inspect it for absorption at the wavelengths of the neutral sodium (Na I) doublet at {lambda}{lambda}5889, 5895 and neutral potassium (K I) at {lambda}7698. We used the transmission spectrum at Ca I {lambda}6122-which shows strong stellar absorption but is not an alkali metal resonance line that we expect to show significant absorption in these atmospheres-as a control line to examine our measurements for systematic errors. We use an empirical Monte Carlo method to quantify these systematic errors. In a reanalysis of the same data set using a reduction and analysis pipeline that was derived independently, we confirm the previously seen Na I absorption in HD 189733b at a level of (- 5.26 {+-} 1.69) Multiplication-Sign 10{sup -4} (the average value over a 12 A integration band to be consistent with previous authors). Additionally, we tentatively confirm the Na I absorption seen in HD 209458b (independently by multiple authors) at a level of (- 2.63 {+-} 0.81) Multiplication-Sign 10{sup -4}, though the interpretation is less clear. Furthermore, we find Na I absorption of (- 3.16 {+-} 2.06) Multiplication-Sign 10{sup -4} at <3{sigma} in HD 149026b; features apparent in the transmission spectrum are consistent with real absorption and indicate this may be a good target for future observations to confirm. No other results (Na I in HD 147506b and Ca I and K I in all four targets) are significant to {>=}3{sigma}, although we observe some features that we argue are primarily artifacts.

  18. The precipitation synthesis of broad-spectrum UV absorber nanoceria

    SciTech Connect

    Nurhasanah, Iis; Sutanto, Heri; Puspaningrum, Nurul Wahyu

    2013-09-09

    In this paper the possibility of nanoceria as broad-spectrum UV absorber was evaluated. Nanoceria were synthesized by precipitation process from cerium nitrate solution and ammonium hydroxide as precipitant agent. Isopropanol was mixed with water as solvent to prevent hard agglomeration. The structure of resulting nanoceria was characterized by x-ray diffractometer (XRD). The transparency in the visible light and efficiency of protection in UV A region were studied using ultraviolet-visible (UV - Vis) spectrophotometer. The results show that nanoceria possess good tranparency in visible light and high UV light absorption. The critical absorption wavelenght of 368 nm was obtained which is desirable for excellent broad-spectrum protection absorbers. Moreover, analysis of photodegradation nanoceria to methylene blue solution shows poor photocatalytic activity. It indicates that nanoceria suitable for used as UV absorber in personal care products.

  19. [HJ1A/HSI radiometric calibration and spectrum response function sensitivity analysis].

    PubMed

    Gao, Hai-liang; Gu, Xing-fa; Yu, Tao; Li, Xiao-ying; Gong, Hui; Li, Jia-guo; Zhu, Guang-hui

    2010-11-01

    Hyper spectrum imager (HSI) loaded on HJ-1A satellite is Chinese first spaceborne hyperspectrum sensor. Since the HSI has no spectrum response function of all channels, the usually used calibration method-reflectance based method has been modified, and a new calibration method is proposed, in which the spectrum response function is neglected. Based on the calibration experiment data of Dunhuang in Aug., 2009, the HSI sensor was calibrated on orbit. The different kinds of spectrum response were constructed based on the formula, and the errors of calibration results with different spectrum response function were analyzed. The results show, expecting for the channels of water vapor and oxygen absorption channel, the influence of spectrum response function in other channel is less than 3%, and the calibration result based on new calibration method can satisfy the application requirement.

  20. Spectrum Recombination.

    ERIC Educational Resources Information Center

    Greenslade, Thomas B., Jr.

    1984-01-01

    Describes several methods of executing lecture demonstrations involving the recombination of the spectrum. Groups the techniques into two general classes: bringing selected portions of the spectrum together using lenses or mirrors and blurring the colors by rapid movement or foreshortening. (JM)

  1. Terahertz spectrum analysis of leather at room temperature

    NASA Astrophysics Data System (ADS)

    Li, Jiusheng; Yao, Jianquan; Li, Jianrui

    2008-12-01

    Over the past ten years, electromagnetic terahertz (THz) frequencies region from 100 GHz to 10 THz (or wavelengths of 30 μm ~3 mm) have received extensive attention and investigation. Terahertz wave detection enables direct calculations of both the imaginary and the real parts of the refractive index without using the Kramers-Kronig relations. There are many potential applications such as radio astronomy, atmospheric studies, remote sensing, and plasma diagnostics. Shoes, neckties and sofa, etc are mainly made of skin of animal, imitated skin and artificial leather. It has important practical value to component analysis and quality assessment by measuring absorption, refractive index, and other optical parameters. In this paper, the spectral characteristics of sheepskin, imitated sheepskin and artificial leather have been measured with terahertz time-domain spectroscopy (THz-TDS) in the range of 0.1~2.0THz. The results show that there have not absorption peak in the absorption spectrum of the sheepskin. However, it is found that there are three absorption peaks in the absorption spectrum of the artificial leather at the frequency of 1.13THz, 1.21THz, and 1.36THz, respectively. The potential application of the leather in THz frequency region is also discussed.

  2. IRIS Spectrum Line Plot

    NASA Video Gallery

    This video shows a line plot of the spectrum. The spectra here are shown for various locations on the Sun. The changes in the movie are caused by differing physical conditions in the locations. Cre...

  3. Terahertz spectrum of gallic acid

    NASA Astrophysics Data System (ADS)

    Wu, Meng; Zhao, Guozhong; Wang, Haiyan; Liang, Chengshen

    2009-11-01

    Gallic acid is natural polyphenol compound found in many green plants. More and more experiments have demonstrated that the gallic acid has comprehensive applications. In the field of medicine, the gallic acid plays an important role in antianaphylaxis, antineoplastic, antimycotic, anti-inflammatory, antivirotic, antiasthmatic and inhibiting the degradation of insulin. It also has a lot of applications in chemical industry, food industry and light industry. So it is important to study the terahertz time-domain spectroscopy of gallic acid. Terahertz time-domain spectroscopy (THz-TDS) is a new coherent spectral technology based on the femtosecond laser. In this work, the spectral characteristics of gallic acid in the range of 0.4 THz to 2.6 THz have been measured by THz-TDS. We obtained its absorption and refraction spectra at room temperature. The vibration absorption spectrum of the single molecule between 0.4 THz and 2.6 THz is simulated based on the Density Functional Theory (DFT). It is found that the gallic acid has the spectral response to THz wave in this frequency range. The results show the abnormal dispersion at 1.51 THz and 2.05 THz. These results can be used in the qualitative analysis of gallic acid and the medicine and food inspection.

  4. [Using 2-DCOS to identify the molecular spectrum peaks for the isomer in the multi-component mixture gases Fourier transform infrared analysis].

    PubMed

    Zhao, An-Xin; Tang, Xiao-Jun; Zhang, Zhong-Hua; Liu, Jun-Hua

    2014-10-01

    The generalized two-dimensional correlation spectroscopy and Fourier transform infrared were used to identify hydrocarbon isomers in the mixed gases for absorption spectra resolution enhancement. The Fourier transform infrared spectrum of n-butane and iso-butane and the two-dimensional correlation infrared spectrum of concentration perturbation were used for analysis as an example. The all band and the main absorption peak wavelengths of Fourier transform infrared spectrum for single component gas showed that the spectra are similar, and if they were mixed together, absorption peaks overlap and peak is difficult to identify. The synchronous and asynchronous spectrum of two-dimensional correlation spectrum can clearly identify the iso-butane and normal butane and their respective characteristic absorption peak intensity. Iso-butane has strong absorption characteristics spectrum lines at 2,893, 2,954 and 2,893 cm(-1), and n-butane at 2,895 and 2,965 cm(-1). The analysis result in this paper preliminary verified that the two-dimensional infrared correlation spectroscopy can be used for resolution enhancement in Fourier transform infrared spectrum quantitative analysis. PMID:25739197

  5. [Simulation of TDLAS direct absorption based on HITRAN database].

    PubMed

    Qi, Ru-birn; He, Shu-kai; Li, Xin-tian; Wang, Xian-zhong

    2015-01-01

    Simulating of the direct absorption TDLAS spectrum can help to comprehend the process of the absorbing and understand the influence on the absorption signal with each physical parameter. Firstly, the basic theory and algorithm of direct absorption TDLAS is studied and analyzed thoroughly, through giving the expressions and calculating steps of parameters based on Lambert-Beer's law, such as line intensity, absorption cross sections, concentration, line shape and gas total partition functions. The process of direct absorption TDLAS is simulated using MATLAB programs based on HITRAN spectra database, with which the absorptions under a certain temperature, pressure, concentration and other conditions were calculated, Water vapor is selected as the target gas, the absorptions of which under every line shapes were simulated. The results were compared with that of the commercial simulation software, Hitran-PC, which showed that, the deviation under Lorentz line shape is less than 0. 5%, and that under Gauss line shape is less than 2. 5%, while under Voigt line shape it is less than 1%. It verified that the algorithm and results of this work are correct and accurate. The absorption of H2O in v2 + v3 band under different pressure and temperature is also simulated. In low pressure range, the Doppler broadening dominant, so the line width changes little with varied.pressure, while the line peak increases with rising pressure. In high pressure range, the collision broadening dominant, so the line width changes wider with increasing pressure, while the line peak approaches to a constant value with rising pressure. And finally, the temperature correction curve in atmosphere detection is also given. The results of this work offer the reference and instruction for the application of TDLAS direct absorption. PMID:25993843

  6. Neuron absorption study and mid-IR optical excitations

    NASA Astrophysics Data System (ADS)

    Guo, Dingkai; Chen, Xing; Vadala, Shilpa; Leach, Jennie; Kostov, Yordan; Bewley, William W.; Kim, Chul-Soo; Kim, Mijin; Canedy, Chadwick L.; Merritt, Charles D.; Vurgaftman, Igor; Meyer, Jerry R.; Choa, Fow-Sen

    2012-02-01

    Neuronal optical excitation can provide non-contacting tools to explore brain circuitry and a durable stimulation interface for cardiac pacing and visual as well as auditory sensory neuronal stimulation. To obtain accurate absorption spectra, we scan the transmission of neurons in cell culture medium, and normalize it by subtracting out the absorption spectrum of the medium alone. The resulting spectra show that the main neuronal absorption peaks are in the 3000- 6000nm band, although there is a smaller peak near 1450nm. By coupling the output of a 3μm interband cascade laser (ICL) into a mid-IR fluorozirconate fiber, we can effectively deliver more than 1J/cm2 photon intensity to the excitation site for neuronal stimulation.

  7. 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.

  8. Strange Latitudinal Variations of the Ammonia Absorption on Jupiter

    NASA Astrophysics Data System (ADS)

    Tejfel, V. G.; Karimov, A. M.; Vdovichenko, V. D.

    2005-08-01

    The ammonia absorption bands at near infrared spectrum of Jupiter are blended with stronger methane absorption and it is hard to study their variations on planetary disk. To extract the ammonia absorption we have used the ratio of Jupiter's spectra to the spectrum of Saturn where the ammonia absorption is very small or absent. Thus we could measure the profile and equivalent widths (W) of the NH3 band at 787 nm as well as the weaker band at 643 nm . More than 200 spectra of Jupiter were recorded in March-May 2004 with spectrograph SGS and CCD-camera ST-7XE at the slit oriented along central meridian or equator. All spectra were processed by this mean. Equatorial spectra show more or less uniform decrease of the NH3 absorption towards both limbs from the disk center. But most of spectra of CM show strange and clearly expressed wide depression of the NH3 band at 787 nm in the temperate latitudes of Northern hemisphere with minimal equivalent widths about 15 A or less when W in Southern hemisphere reach of 20 A or more. We have analyzed all probable artificial reasons of this effect but did not find any influence of instrumental factors. Then we processed a number of Jupiter's spectra recorded in 1997-1998 with other spectrograph and CCD ST-6V and detected the same peculiarity. Finally there were measured 100 zonal spectra ( with slit oriented parallel to equator) scanned all Jupiter's disk from North pole to South pole and recorded 3 May 2005 near upper culmination of the planet. The result is the same: the significant depression of the ammonia absorption in the N-hemisphere of Jupiter is confirmed. We shall continue the study and analysis of this effect to be sure that it is real peculiarity of the gaseous ammonia distribution and behavior on Jupiter.

  9. Sound absorption of porous substrates covered by foliage: experimental results and numerical predictions.

    PubMed

    Ding, Lei; Van Renterghem, Timothy; Botteldooren, Dick; Horoshenkov, Kirill; Khan, Amir

    2013-12-01

    The influence of loose plant leaves on the acoustic absorption of a porous substrate is experimentally and numerically studied. Such systems are typical in vegetative walls, where the substrate has strong acoustical absorbing properties. Both experiments in an impedance tube and theoretical predictions show that when a leaf is placed in front of such a porous substrate, its absorption characteristics markedly change (for normal incident sound). Typically, there is an unaffected change in the low frequency absorption coefficient (below 250 Hz), an increase in the middle frequency absorption coefficient (500-2000 Hz) and a decrease in the absorption at higher frequencies. The influence of leaves becomes most pronounced when the substrate has a low mass density. A combination of the Biot's elastic frame porous model, viscous damping in the leaf boundary layers and plate vibration theory is implemented via a finite-difference time-domain model, which is able to predict accurately the absorption spectrum of a leaf above a porous substrate system. The change in the absorption spectrum caused by the leaf vibration can be modeled reasonably well assuming the leaf and porous substrate properties are uniform.

  10. The absorption spectrum of D2: ultrasensitive cavity ring down spectroscopy of the (2-0) band near 1.7 μm and accurate ab initio line list up to 24,000 cm(-1).

    PubMed

    Kassi, Samir; Campargue, Alain; Pachucki, Krzysztof; Komasa, Jacek

    2012-05-14

    Eleven very weak electric quadrupole transitions Q(2), Q(1), S(0)-S(8) of the first overtone band of D(2) have been measured by very high sensitivity CW-cavity ring down spectroscopy (CRDS) between 5850 and 6720 cm(-1). The noise equivalent absorption of the recordings is on the order of α(min) ≈ 3 × 10(-11) cm(-1). By averaging a high number of spectra, the noise level was lowered to α(min) ≈ 4 × 10(-12) cm(-1) in order to detect the S(8) transition which is among the weakest transitions ever detected in laboratory experiments (line intensity on the order of 1.8 × 10(-31) cm/molecule at 296 K). A Galatry profile was used to reproduce the measured line shape and derive the line strengths. The pressure shift and position at zero pressure limit were determined from recordings with pressures ranging between 10 and 750 Torr. A highly accurate theoretical line list was constructed for pure D(2) at 296 K. The intensity threshold was fixed to a value of 1 × 10(-34) cm/molecule at 296 K. The obtained line list is provided as supplementary material. It extends up to 24,000 cm(-1) and includes 201 transitions belonging to ten v-0 cold bands (v = 0-9) and three v-1 hot bands (v = 1-3). The energy levels include the relativistic and quantum electrodynamic corrections as well as the effects of the finite nuclear mass. The quadrupole transition moments are calculated using highly accurate adiabatic wave functions. The CRDS line positions and intensities of the first overtone band are compared to the corresponding calculated values and to previous measurements of the S(0)-S(3) lines. The agreement between the CRDS and theoretical results is found within the claimed experimental uncertainties (on the order of 1 × 10(-3) cm(-1) and 2% for the positions and intensities, respectively) while the previous S(0)-S(3) measurements showed important deviations for the line intensities.

  11. [Retrieval of NO2 total vertical columns by direct-sun differential optical absorption spectroscopy].

    PubMed

    Wang, Yang; Xie, Pin-hua; Li, Ang; Xu, Jin; Zeng, Yi; Si, Fu-qi; Wu, Feng-cheng

    2012-04-01

    An appropriate reference spectrum is essential for the direct-sun differential optical absorption spectroscopy (DS-DOAS). It depends on the real reference spectrum to retrieve the total vertical column density (VCD). The spectrum detected at the time with minimum sun zenith angle under the relative clear atmospheric condition in the measurement period was conventionally selected as the reference spectrum. Because there is still untracked NO2 absorption structure in the reference spectrum, the VCD retrieved based on the above spectrum is actually relative VCD, which results in larger error. To solve this problem, a new method was investigated. A convolution of extraterrestrial high-precision solar Fraunhofer spectrum and the instrumental function of the spectrometer was computed and chosen as the reference spectrum. The error induced by NO2 absorption structure in the reference spectrum was removed. Then the fitting error of slant column density (SCD) retrieved by this method was analyzed. The correlation between the absolute SCD and the differential slant column density (dSCD) was calculated. The result shows that the error of SCD retrieved by this new method is below 1.6 x 10(16) molecules x cm(-2) on March 7, 2011, while the error generated by the normal method is about 4.25 x 10(16) molecules x cm(-2). The new method decreased more than 62% error. In addition, the results throughout the day were compared to the troposphere VCD from MAX-DOAS and they are in good agreement. It indicates that the new method could effectively reduce the VCD error of the common way. PMID:22715747

  12. Determination of the major groups of phytoplankton pigments from the absorption spectra of total particulate matter

    NASA Technical Reports Server (NTRS)

    Hoepffner, Nicolas; Sathyendranath, Shubha

    1993-01-01

    The contributions of detrital particles and phytoplankton to total light absorption are retrieved by nonlinear regression on the absorption spectra of total particles from various oceanic regions. The model used explains more than 96% of the variance in the observed particle absorption spectra. The resulting absorption spectra of phytoplankton are then decomposed into several Gaussian bands reflecting absorption by phytoplankton pigments. Such a decomposition, combined with high-performance liquid chromatography data on phytoplankton pigment concentrations, allows the computation of specific absorption coefficients for chlorophylls a, b, and c and carotenoids. The spectral values of these in vivo absorption coefficients are then discussed, considering the effects of secondary pigments which were not measured quantitatively. We show that these coefficients can be used to reconstruct the absorption spectra of phytoplankton at various locations and depths. Discrepancies that do occur at some stations are explained in terms of particle size effect. These coefficients can be used to determine the concentrations of phytoplankton pigments in the water, given the absorption spectrum of total particles.

  13. Influence of texture modifications in silicon solar cells on absorption in the intrinsic layers

    NASA Astrophysics Data System (ADS)

    Ermes, M.; Bittkau, K.; Carius, R.

    2012-06-01

    The influence of the front texture of an etched transparent conductive oxide with crater-like structures of various sizes on the absorption of a thin amorphous silicon (a-Si:H) layer is investigated by rigorous optical simulations as part of two simplified systems: A simplified single junction device, using a perfect metal as back contact and a top cell of an amorphous/microcrystalline silicon tandem device, using a microcrystalline silicon halfspace adjacent to the amorphous layer. The texture is modified by stretching either in height or laterally and the average absorption in the a-Si:H layer is investigated relative to the original structure. We investigate the average absorption for each wavelength as well as the total absorption, weighted with an AM1.5g spectrum. Furthermore, the local absorption distribution inside the a-Si:H layer is examined to improve the understanding of local texture features and their influence on absorption and cell performance. For both modifications, an optimal point can be found to improve the absorption in the amorphous layer by up to 15% and 6% for a simplified single junction and tandem top cell, respectively. In case of the top cell of the simplified tandem device, it is found that additionally, the transmission into the microcrystalline silicon can be improved. Also, the local absorption distribution shows that there is an optimal size of the surface craters for all modifications, while steeper crater rims in general lead to higher absorption.

  14. Light absorption properties and absorption budget of Southeast Pacific waters

    NASA Astrophysics Data System (ADS)

    Bricaud, Annick; Babin, Marcel; Claustre, Hervé; Ras, JoséPhine; TièChe, Fanny

    2010-08-01

    Absorption coefficients of phytoplankton, nonalgal particles (NAPs), and colored dissolved organic matter (CDOM), and their relative contributions to total light absorption, are essential variables for bio-optical and biogeochemical models. However, their actual variations in the open ocean remain poorly documented, particularly for clear waters because of the difficulty in measuring very low absorption coefficients. The Biogeochemistry and Optics South Pacific Experiment (BIOSOPE) cruise investigated a large range of oceanic regimes, from mesotrophic waters around the Marquesas Islands to hyperoligotrophic waters in the subtropical gyre and eutrophic waters in the upwelling area off Chile. The spectral absorption coefficients of phytoplankton and NAPs were determined using the filter technique, while the CDOM absorption coefficients were measured using a 2 m capillary waveguide. Over the whole transect, the absorption coefficients of both dissolved and particulate components covered approximately two orders of magnitude; in the gyre, they were among the lowest ever reported for open ocean waters. In the oligotrophic and mesotrophic waters, absorption coefficients of phytoplankton and NAPs were notably lower than those measured in other oceanic areas with similar chlorophyll contents, indicating some deviation from the standard chlorophyll-absorption relationships. The contribution of absorption by NAPs to total particulate absorption showed large vertical and horizontal variations. CDOM absorption coefficients covaried with algal biomass, albeit with a high scatter. The spectral slopes of both NAP and CDOM absorption revealed structured spatial variability in relation with the trophic conditions. The relative contributions of each component to total nonwater absorption were (at a given wavelength) weakly variable over the transect, at least within the euphotic layer.

  15. THE STRUCTURE OF THE ULTRAVIOLET ABSORPTION SPECTRA OF CERTAIN PROTEINS AND AMINO ACIDS

    PubMed Central

    Coulter, Calvin B.; Stone, Florence M.; Kabat, Elvin A.

    1936-01-01

    1. The absorption spectra of a number of proteins in the region 2500 to 3000 A. have been found to comprise from six to nine narrow bands. In consequence of variation in the relative intensity of these bands from protein to protein, the absorption curve has a characteristic configuration for each protein. 2. These bands correspond closely in position with the narrow bands which appear in the absorption spectra of tryptophan, tyrosin, and phenylalanine. Tryptophan and tyrosin each present three bands, phenylalanine shows nine. 3. The bands in the proteins are accordingly attributed to these amino acids. In the proteins the bands are displaced from the positions which they occupy in the uncombined amino acids, in most instances, by 10 to 35 A. toward longer wavelengths. 4. The absorption spectrum of Pneumococcus Type I antibody resembles that of normal pseudoglobulin but shows characteristic differences. PMID:19872958

  16. Further advancement of differential optical absorption spectroscopy: theory of orthogonal optical absorption spectroscopy.

    PubMed

    Liudchik, Alexander M

    2014-08-10

    A modified version of the differential optical absorption spectroscopy (DOAS) method is presented. The technique is called orthogonal optical absorption spectroscopy (OOAS). A widespread variant of DOAS with smoothing of the registered spectrum and absorption cross sections being made employing a polynomial regression is a particular case of OOAS. The concept of OOAS provides a variety of new possibilities for constructing computational schemes and analyzing the influence of different error sources on calculated concentrations. PMID:25320931

  17. 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.

  18. 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)

  19. Hydrogen Spectrum

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    The series of absorption or emission lines that are characteristic of the hydrogen atom. According to the Bohr theory of the hydrogen atom, devised by Danish physicist Neils Bohr (1885-1962) in 1913, the hydrogen atom can be envisaged as consisting of a central nucleus (a proton) around which a single electron revolves. The electron is located in one of a number of possible permitted orbits, each...

  20. Decays of the Three Top Contributors to the Reactor ν¯e High-Energy Spectrum, 92Rb, Ygs96 , and 142Cs, Studied with Total Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Rasco, B. C.; Wolińska-Cichocka, M.; Fijałkowska, A.; Rykaczewski, K. P.; Karny, M.; Grzywacz, R. K.; Goetz, K. C.; Gross, C. J.; Stracener, D. W.; Zganjar, E. F.; Batchelder, J. C.; Blackmon, J. C.; Brewer, N. T.; Go, S.; Heffron, B.; King, T.; Matta, J. T.; Miernik, K.; Nesaraja, C. D.; Paulauskas, S. V.; Rajabali, M. M.; Wang, E. H.; Winger, J. A.; Xiao, Y.; Zachary, C. J.

    2016-08-01

    We report total absorption spectroscopy measurements of 92Rb, Ygs96 , and 142Cs β decays, which are the most important contributors to the high energy ν¯e spectral shape in nuclear reactors. These three β decays contribute 43% of the ν¯e flux near 5.5 MeV emitted by nuclear reactors. This ν¯e energy is particularly interesting due to spectral features recently observed in several experiments including the Daya Bay, Double Chooz, and RENO Collaborations. Measurements were conducted at Oak Ridge National Laboratory by means of proton-induced fission of 238U with on-line mass separation of fission fragments and the Modular Total Absorption Spectrometer. We observe a β -decay pattern that is similar to recent measurements of 92Rb, with a ground-state to ground-state β feeding of 91(3)%. We verify the Ygs96 ground-state to ground-state β feeding of 95.5(20)%. Our measurements substantially modify the β -decay feedings of 142Cs, reducing the β feeding to 142Ba states below 2 MeV by 32% when compared with the latest evaluations. Our results increase the discrepancy between the observed and the expected reactor ν¯e flux between 5 and 7 MeV, the maximum excess increases from ˜10 % to ˜12 %.

  1. Decays of the Three Top Contributors to the Reactor ν[over ¯]_{e} High-Energy Spectrum, ^{92}Rb, ^{96gs}Y, and ^{142}Cs, Studied with Total Absorption Spectroscopy.

    PubMed

    Rasco, B C; Wolińska-Cichocka, M; Fijałkowska, A; Rykaczewski, K P; Karny, M; Grzywacz, R K; Goetz, K C; Gross, C J; Stracener, D W; Zganjar, E F; Batchelder, J C; Blackmon, J C; Brewer, N T; Go, S; Heffron, B; King, T; Matta, J T; Miernik, K; Nesaraja, C D; Paulauskas, S V; Rajabali, M M; Wang, E H; Winger, J A; Xiao, Y; Zachary, C J

    2016-08-26

    We report total absorption spectroscopy measurements of ^{92}Rb, ^{96gs}Y, and ^{142}Cs β decays, which are the most important contributors to the high energy ν[over ¯]_{e} spectral shape in nuclear reactors. These three β decays contribute 43% of the ν[over ¯]_{e} flux near 5.5 MeV emitted by nuclear reactors. This ν[over ¯]_{e} energy is particularly interesting due to spectral features recently observed in several experiments including the Daya Bay, Double Chooz, and RENO Collaborations. Measurements were conducted at Oak Ridge National Laboratory by means of proton-induced fission of ^{238}U with on-line mass separation of fission fragments and the Modular Total Absorption Spectrometer. We observe a β-decay pattern that is similar to recent measurements of ^{92}Rb, with a ground-state to ground-state β feeding of 91(3)%. We verify the ^{96gs}Y ground-state to ground-state β feeding of 95.5(20)%. Our measurements substantially modify the β-decay feedings of ^{142}Cs, reducing the β feeding to ^{142}Ba states below 2 MeV by 32% when compared with the latest evaluations. Our results increase the discrepancy between the observed and the expected reactor ν[over ¯]_{e} flux between 5 and 7 MeV, the maximum excess increases from ∼10% to ∼12%. PMID:27610847

  2. Decays of the Three Top Contributors to the Reactor ν[over ¯]_{e} High-Energy Spectrum, ^{92}Rb, ^{96gs}Y, and ^{142}Cs, Studied with Total Absorption Spectroscopy.

    PubMed

    Rasco, B C; Wolińska-Cichocka, M; Fijałkowska, A; Rykaczewski, K P; Karny, M; Grzywacz, R K; Goetz, K C; Gross, C J; Stracener, D W; Zganjar, E F; Batchelder, J C; Blackmon, J C; Brewer, N T; Go, S; Heffron, B; King, T; Matta, J T; Miernik, K; Nesaraja, C D; Paulauskas, S V; Rajabali, M M; Wang, E H; Winger, J A; Xiao, Y; Zachary, C J

    2016-08-26

    We report total absorption spectroscopy measurements of ^{92}Rb, ^{96gs}Y, and ^{142}Cs β decays, which are the most important contributors to the high energy ν[over ¯]_{e} spectral shape in nuclear reactors. These three β decays contribute 43% of the ν[over ¯]_{e} flux near 5.5 MeV emitted by nuclear reactors. This ν[over ¯]_{e} energy is particularly interesting due to spectral features recently observed in several experiments including the Daya Bay, Double Chooz, and RENO Collaborations. Measurements were conducted at Oak Ridge National Laboratory by means of proton-induced fission of ^{238}U with on-line mass separation of fission fragments and the Modular Total Absorption Spectrometer. We observe a β-decay pattern that is similar to recent measurements of ^{92}Rb, with a ground-state to ground-state β feeding of 91(3)%. We verify the ^{96gs}Y ground-state to ground-state β feeding of 95.5(20)%. Our measurements substantially modify the β-decay feedings of ^{142}Cs, reducing the β feeding to ^{142}Ba states below 2 MeV by 32% when compared with the latest evaluations. Our results increase the discrepancy between the observed and the expected reactor ν[over ¯]_{e} flux between 5 and 7 MeV, the maximum excess increases from ∼10% to ∼12%.

  3. UV spectrum of Enceladus

    NASA Astrophysics Data System (ADS)

    Zastrow, Mark; Clarke, John T.; Hendrix, Amanda R.; Noll, Keith S.

    2012-07-01

    We present a far ultraviolet (FUV) spectrum of Saturn’s moon Enceladus from the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST). We have put upper limits on emission from C, N, and O lines in Enceladus’ atmosphere and column densities for the C lines assuming solar resonance scattering. We find these upper limits to be relatively low-on the order of tens to thousands of Rayleighs and with C column densities on the order of 108-1015 cm-2, depending on the assumed source size. We also present a segment of a reflectance spectrum in the FUV from ∼1900-2130 Å. This region was sensitive to the different ice mixtures in the model spectra reported by Hendrix et al. (Hendrix, A.R., Hansen, C.J., Holsclaw, G.M. [2010]. Icarus, 206, 608). We find the spectrum brightens quickly longward of ∼1900 Å, constraining the absorption band observed by Hendrix et al. from ∼170 to 190 nm. We find our data is consistent with the suggestion of Hendrix et al. of the presence of ammonia ice (or ammonia hydrate) to darken that region, and also possibly tholins to darken the mid-UV, as reported by Verbiscer et al. (Verbiscer, A.J., French, R.G., McGhee, C.A. [2005]. Icarus, 173, 66).

  4. [Qualitative Determination of Organic Vapour Using Violet and Visible Spectrum].

    PubMed

    Jiang, Bo; Hu, Wen-zhong; Liu, Chang-jian; Zheng, Wei; Qi, Xiao-hui; Jiang, Ai-li; Wang, Yan-ying

    2015-12-01

    Vapours of organic matters were determined qualitatively employed with ultraviolet-visible absorption spectroscopy. Vapours of organic matters were detected using ultraviolet-visible spectrophotometer employing polyethylene film as medium, the ultraviolet and visible absorption spectra of vegetable oil vapours of soybean oil, sunflower seed oil, peanut oil, rapeseed oil, sesame oil, cotton seed oil, tung tree seed oil, and organic compound vapours of acetone, ethyl acetate, 95% ethanol, glacial acetic acid were obtained. Experimental results showed that spectra of the vegetable oil vapour and the organic compound vapour could be obtained commendably, since ultra violet and visible spectrum of polyethylene film could be deducted by spectrograph zero setting. Different kinds of vegetable oils could been distinguished commendably in the spectra since the λ(max), λ(min), number of absorption peak, position, inflection point in the ultra violet and visible spectra obtained from the vapours of the vegetable oils were all inconsistent, and the vapours of organic compounds were also determined perfectly. The method had a good reproducibility, the ultraviolet and visible absorption spectra of the vapours of sunflower seed oil in 10 times determination were absolutely the same. The experimental result indicated that polyethylene film as a kind of medium could be used for qualitative analysis of ultraviolet and visible absorption spectroscopy. The method for determination of the vapours of the vegetable oils and organic compounds had the peculiarities of fast speed analysis, well reproducibility, accuracy and reliability and low cost, and so on. Ultraviolet and visible absorption spectrum of organic vapour could provide feature information of material vapour and structural information of organic compound, and provide a novel test method for identifying vapour of compound and organic matter.

  5. [Qualitative Determination of Organic Vapour Using Violet and Visible Spectrum].

    PubMed

    Jiang, Bo; Hu, Wen-zhong; Liu, Chang-jian; Zheng, Wei; Qi, Xiao-hui; Jiang, Ai-li; Wang, Yan-ying

    2015-12-01

    Vapours of organic matters were determined qualitatively employed with ultraviolet-visible absorption spectroscopy. Vapours of organic matters were detected using ultraviolet-visible spectrophotometer employing polyethylene film as medium, the ultraviolet and visible absorption spectra of vegetable oil vapours of soybean oil, sunflower seed oil, peanut oil, rapeseed oil, sesame oil, cotton seed oil, tung tree seed oil, and organic compound vapours of acetone, ethyl acetate, 95% ethanol, glacial acetic acid were obtained. Experimental results showed that spectra of the vegetable oil vapour and the organic compound vapour could be obtained commendably, since ultra violet and visible spectrum of polyethylene film could be deducted by spectrograph zero setting. Different kinds of vegetable oils could been distinguished commendably in the spectra since the λ(max), λ(min), number of absorption peak, position, inflection point in the ultra violet and visible spectra obtained from the vapours of the vegetable oils were all inconsistent, and the vapours of organic compounds were also determined perfectly. The method had a good reproducibility, the ultraviolet and visible absorption spectra of the vapours of sunflower seed oil in 10 times determination were absolutely the same. The experimental result indicated that polyethylene film as a kind of medium could be used for qualitative analysis of ultraviolet and visible absorption spectroscopy. The method for determination of the vapours of the vegetable oils and organic compounds had the peculiarities of fast speed analysis, well reproducibility, accuracy and reliability and low cost, and so on. Ultraviolet and visible absorption spectrum of organic vapour could provide feature information of material vapour and structural information of organic compound, and provide a novel test method for identifying vapour of compound and organic matter. PMID:26964229

  6. Demonstration That Calibration of the Instrument Response to Polarizations Parallel and Perpendicular to the Object Space Projected Slit of an Imaging Spectrometer Enable Measurement of the Atmospheric Absorption Spectrum in Region of the Weak CO2 Band for the Case of Arbitrary Polarization: Implication for the Geocarb Mission

    NASA Astrophysics Data System (ADS)

    Kumer, J. B.; Rairden, R. L.; Polonsky, I. N.; O'Brien, D. M.

    2014-12-01

    The Tropospheric Infrared Mapping Spectrometer (TIMS) unit rebuilt to operate in a narrow spectral region, approximately 1603 to 1615 nm, of the weak CO2 band as described by Kumer et al. (2013, Proc. SPIE 8867, doi:10.1117/12.2022668) was used to conduct the demonstration. An integrating sphere (IS), linear polarizers and quarter wave plate were used to confirm that the instrument's spectral response to unpolarized light, to 45° linearly polarized light and to circular polarized light are identical. In all these cases the intensity components Ip = Is where Ip is the component parallel to the object space projected slit and Is is perpendicular to the slit. In the circular polarized case Ip = Is in the time averaged sense. The polarizer and IS were used to characterize the ratio Rθ of the instrument response to linearly polarized light at the angle θ relative to parallel from the slit, for increments of θ from 0 to 90°, to that of the unpolarized case. Spectra of diffusely reflected sunlight passed through the polarizer in increments of θ, and divided by the respective Rθ showed identical results, within the noise limit, for solar spectrum multiplied by the atmospheric transmission and convolved by the Instrument Line Shape (ILS). These measurements demonstrate that unknown polarization in the diffusely reflected sunlight on this small spectral range affect only the slow change across the narrow band in spectral response relative to that of unpolarized light and NOT the finely structured / high contrast spectral structure of the CO2 atmospheric absorption that is used to retrieve the atmospheric content of CO2. The latter is one of the geoCARB mission objectives (Kumer et al, 2013). The situation is similar for the other three narrow geoCARB bands; O2 A band 757.9 to 768.6 nm; strong CO2 band 2045.0 to 2085.0 nm; CH4 and CO region 2300.6 to 2345.6 nm. Polonsky et al have repeated the mission simulation study doi:10.5194/amt-7-959-2014 assuming no use of a geo

  7. The absorption spectrum of H2: CRDS measurements of the (2-0) band, review of the literature data and accurate ab initio line list up to 35000 cm(-1).

    PubMed

    Campargue, Alain; Kassi, Samir; Pachucki, Krzysztof; Komasa, Jacek

    2012-01-14

    Five very weak transitions-O(2), O(3), O(4), O(5) and Q(5)-of the first overtone band of H(2) are measured by very high sensitivity CW-Cavity Ring Down Spectroscopy (CRDS) between 6900 and 7920 cm(-1). The noise equivalent absorption of the recordings is on the order of α(min)≈ 5 × 10(-11) cm(-1) allowing for the detection of the O(5) transition with an intensity of 1.1 × 10(-30) cm per molecule, the smallest intensity value measured so far for an H(2) absorption line. A Galatry profile was used to reproduce the measured line shape and derive the line strengths. The pressure shift of the O(2) and O(3) lines was accurately determined from a series of recordings with pressure ranging between 10 and 700 Torr. From an exhaustive review of the literature data, the list of H(2) absorption lines detected so far has been constructed. It includes a total of 39 transitions ranging from the S(0) pure rotational line near 354 cm(-1) up to the S(1) transition of the (5-0) band near 18,908 cm(-1). These experimental values are compared to a highly accurate theoretical line list constructed for pure H(2) at 296 K (0-35,000 cm(-1), intensity cut off of 1 × 10(-34) cm per molecule). The energy levels and transition moments were computed from high level quantum mechanics calculations. The overall agreement between the theoretical and experimental values is found to be very good for the line positions. Some deviations for the intensities of the high overtone bands (V > 2) are discussed in relation with possible pressure effects affecting the retrieved intensity values. We conclude that the hydrogen molecule is probably a unique case in rovibrational spectroscopy for which first principles theory can provide accurate spectroscopic parameters at the level of the performances of the state of the art experimental techniques.

  8. Absorption of femtosecond laser pulses in interaction with solid targets.

    PubMed

    Dong, Q L; Zhang, J; Teng, H

    2001-08-01

    We have studied the effects of the plasma density scale length on the absorption mechanism of the femtosecond (fs) laser pulses interacting with solid targets. Experiments and particle-in-cell (PIC) simulations demonstrate that the vacuum heating is the main absorption in the plasma in the interaction of fs laser pulses with solid targets when no prepulses are applied. The energy spectrum of hot electrons ejected out of or injected into the plasma show a bitemperature distribution. While the first temperature of the two groups of hot electrons can be attributed to the "pull-and-push" exertion of the laser field, the second temperature refers to the electrons accelerated by the static part (in front of the target) and the oscillating part (in the plasma layer) of the laser-induced electric field, respectively. PIC simulations also show that with an appropriate density scale length, the femtosecond laser energy can be absorbed locally through different mechanisms.

  9. Atmospheric absorption of high frequency noise and application to fractional-octave bands

    NASA Technical Reports Server (NTRS)

    Shields, F. D.; Bass, H. E.

    1977-01-01

    Pure tone sound absorption coefficients were measured at 1/12 octave intervals from 4 to 100 KHz at 5.5K temperature intervals between 255.4 and 310.9 K and at 10 percent relative humidity increments between 0 percent and saturation in a large cylindrical tube (i.d., 25.4 cm; length, 4.8 m). Special solid-dielectric capacitance transducers, one to generate bursts of sound waves and one to terminate the sound path and detect the tone bursts, were constructed to fit inside the tube. The absorption was measured by varying the transmitter receiver separation from 1 to 4 m and observing the decay of multiple reflections or change in amplitude of the first received burst. The resulting absorption was compared with that from a proposed procedure for computing sound absorption in still air. Absorption of bands of noise was numerically computed by using the pure tone results. The results depended on spectrum shape, on filter type, and nonlinearly on propagation distance. For some of the cases considered, comparison with the extrapolation of ARP-866A showed a difference as large as a factor of 2. However, for many cases, the absorption for a finite band was nearly equal to the pure tone absorption at the center frequency of the band. A recommended prediction procedure is described for 1/3 octave band absorption coefficients.

  10. Optical absorption of sodium copper chlorophyllin thin films in UV-vis-NIR region.

    PubMed

    Farag, A A M

    2006-11-01

    The optical absorption studies of sodium copper chlorophyllin thin films (SCC), prepared by spray pyrolysis, in the UV-vis-NIR region was reported for the first time. Several new discrete transitions are observed in the UV-vis region of the spectra in addition to a strong continuum component in the IR region. The spectra of the infrared absorption allow characterization of vibration modes for the powder and thin films of SCC. The absorption spectrum recorded in the UV-vis region showed different absorption bands, namely the Soret (B) in the region 340-450 nm and Q-band in the region 600-700 nm and other band labeled N in the 240-320 region. Some important spectral parameters namely optical absorption coefficient (alpha), molar extinction coefficient (epsilon(molar)), oscillator strength (f), electric dipole strength (q(2)) and absorption half bandwidth (Deltalambda) of the principle optical transitions were evaluated. The analysis of the absorption coefficient in the absorption region revealed direct transitions and the energy gap was estimated as 1.63 eV. Discussion of the obtained results and their comparison with the previous published data are also given.

  11. Reinvestigation of the triplet-minus-singlet spectrum of chloroplasts.

    PubMed

    Jávorfi, T; Garab, G; Naqvi, K R

    2000-01-01

    A comparison of the triplet-minus-singlet (TmS) absorption spectrum of spinach chloroplasts, recorded some thirty years ago, with the more recently published TmS spectrum of isolated Chla/b LHCII (light-harvesting complexes associated with photosystem II of higher plants) shows that the two spectra are very similar, which is to be expected, since only the carotenoid pigments contribute to each spectrum. Be that as it may, the comparison also reveals a dissimilarity: photoexcitation of the sample does, or does not, affect the absorbance in the Qy region (650-700 nm), depending on whether the sample is a suspension of chloroplasts or of isolated LHCII. The Qy-signal in the TmS spectrum of LHCII decays, it should be noted, at the same rate as the rest of the difference spectrum, and its most prominent feature is a negative peak. As the carotenoids do not absorb in the Qy region, the presence of a signal in this region calls for an explanation: van der Vos, Carbonera and Hoff, the first to find as well as fathom the phenomenon, attributed the Qy-signal to a change, in the absorption spectrum of a chlorophyll a (Chla) molecule, brought about by the presence of triplet excitation on a neighbouring carotenoid (Car). The difference in the behaviours of chloroplasts and LHCII, if reproducible, would imply that the Car triplets which give rise to the TmS spectrum of chloroplasts do not influence the absorption spectra of their Chla neighbours. With a view to reaching a firm conclusion about this vexed issue, spinach chloroplasts and thylakoids have been examined with the aid of the same kinetic spectrometer as that used for investigating LHCII; the TmS spectra of both chloroplasts and thylakoids contain prominent bleaching signals centred at 680 nm, and the triplet decay time in each case is comparable to that of the Chla/b LHCII triplets. Results pertaining to other closely related systems are recalled, and it is concluded that, so far as the overall appearance of the Tm

  12. First-principles calculations of K-shell X-ray absorption spectra for warm dense nitrogen

    NASA Astrophysics Data System (ADS)

    Li, Zi; Zhang, Shen; Wang, Cong; Kang, Wei; Zhang, Ping

    2016-05-01

    X-ray absorption spectrum is a powerful tool for atomic structure detection on warm dense matter. Here, we perform first-principles molecular dynamics and X-ray absorption spectrum calculations on warm dense nitrogen along a Hugoniot curve. From the molecular dynamics trajectory, the detailed atomic structures are examined for each thermodynamical condition. The K-shell X-ray absorption spectrum is calculated, and its changes with temperature and pressure along the Hugoniot curve are discussed. The warm dense nitrogen systems may contain isolated nitrogen atoms, N2 molecules, and nitrogen clusters, which show quite different contributions to the total X-ray spectrum due to their different electron density of states. The changes of X-ray spectrum along the Hugoniot curve are caused by the different nitrogen structures induced by the temperature and the pressure. Some clear signatures on X-ray spectrum for different thermodynamical conditions are pointed out, which may provide useful data for future X-ray experiments.

  13. [Mineral Spectrum Change Analysis under the Conditions of Different Particle Size].

    PubMed

    Wang, Yan-xia; Wu, Jian; Zhou, Liang-guang; Hou, Lan-gong; Wang, Dong; Cao, Min

    2015-03-01

    Mineral particle size is an important factor affecting mineral spectrum characteristics, so to explore the changes of the mineral spectrum curves under different particle sizes and the spectrum difference of different minerals under the same particle size are the keys of hyperspectral remote sensing information mineral identification and the theoretical basis of research on spectral differences of different particle -sizes. Six kinds of collected minerals were observed by spectrometer to get the reflectivity spectrum curve and first order differential spectral curve under different particle sizes, and the spectral characteristics of various kinds of minerals under different particle sizes were analyzed. At the same time, spectrum difference of different mineral under the same particle size was compared to explore possible wavelengths of hyperspectral remote sensing mineral identify. Results show that the spectrum curves of various minerals have a larger difference with the change of the particle size, but change law is not the same. The whole spectrum curve of hypersthene will be decreased with the increase of particle size, and the spectrum curve at a specific wavelength range of antigorite, hematite, kaolinite and chlorite will be decreased with the increase of particle size, and there is no direct correlation between the spectrum of olivine and the particle size. Under the same size, different mineral spectral reflectance change a lot in most band range and it provides the possibility for high precision identification of mineral. Antigorite, kaolinite and chlorite all have more absorption peaks of narrow width and smaller intensity than the other minerals. Spectrum curves of hematite, olivine and hypersthene are relatively smooth, and the number of the absorption and reflection peaks is relatively small. This study aims at providing basic data and theoretical support for mineral spectral library construction and mineral hyperspectral identification technology.

  14. [The Establishment of the Method of the Fiber Optic Chemical Sensor Synchronous Absorption-Fluorescence].

    PubMed

    Zhang Li-hua; Iburaim, Arkin

    2016-03-01

    A new method of simultaneously measuring fiber-optic chemical sensor absorption spectrum and fluorescence spectrum is established. Make synchronous absorption-fluorescence cuvette, establish synchronous absorption-fluorescence spectrometry instrumentation combined by fiber optic chemical sensor technology, measure the synchronous absorption-fluorescence spectrums of solutions of rhodamine B, vitamin B2 and vitamin B6, compared by absorption spectroscopy measured by traditional UV-Visible photometric method and fluorescence spectroscopy measured by traditional fluorescence method. Synchronous absorption-fluorescence method measure absorption spectrums and fluorescence spectrums the same to traditional photometric and fluorescence spectroscopy of rhodamine B, vitamin B2 and vitamin B6. The maximum wavelength of fluorescence intensity method has high accuracy relatively compared with fluorescence, but the maximum wavelength of absorption has a slight deviation. Synchronous absorption-fluorescence method means simultaneously measure the absorption spectrums and fluorescence spectrums of the fluorescent substance, making two spectrums to one. The method measured the maximum emission wavelength with high accuracy, though in measuring maximum absorption wavelength there is a slight deviation, but it is worth further studying. PMID:27400519

  15. 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.

  16. Absorption driven focus shift

    NASA Astrophysics Data System (ADS)

    Harrop, N.; Wolf, S.; Maerten, O.; Dudek, K.; Ballach, S.; Kramer, R.

    2016-03-01

    Modern high brilliance near infrared lasers have seen a tremendous growth in applications throughout the world. Increased productivity has been achieved by higher laser power and increased brilliance of lasers. Positive impacts on the performance and costs of parts are opposed to threats on process stability and quality, namely shift of focus position over time. A high initial process quality will be reduced by contamination of optics, eventually leading to a focus shift or even destruction of the optics. Focus analysis at full power of multi-kilowatt high brilliance lasers is a very demanding task because of high power densities in the spot and the high power load on optical elements. With the newly developed high power projection optics, the High-Power Micro-Spot Monitor High Brilliance (HP-MSM-HB) is able to measure focus diameter as low as 20 μm at power levels up to 10 kW at very low internal focus shift. A main driving factor behind thermally induced focus shift is the absorption level of the optical element. A newly developed measuring system is designed to determine the relative absorption level in reference to a gold standard. Test results presented show a direct correlation between absorption levels and focus shift. The ability to determine the absorption level of optical elements as well as their performance at full processing power before they are put to use, enables a high level of quality assurance for optics manufacturers and processing head manufacturers alike.

  17. Design and Testing of a 10B4C Capsule for Spectral-Tailoring in Mixed-Spectrum Reactors

    SciTech Connect

    Greenwood, Lawrence R.; Wittman, Richard S.; Metz, Lori A.; Finn, Erin C.; Friese, Judah I.

    2014-04-11

    A boron carbide capsule highly enriched in 10B has been designed and used for spectral-tailoring experiments at the TRIGA reactor at Washington State University. New experiments show that enriching the boron to 96% B-10 results in additional absorption of neutrons in the resonance region thereby producing a neutron spectrum that is much closer to a pure 235U fission spectrum. A cadmium outer cover was used to reduce thermal heating. The neutron spectrum calculated with MCNP was found to be in very good agreement with measured activation rates from neutron fluence monitors.

  18. Ultra high energy neutrinos: absorption, thermal effects and signatures

    SciTech Connect

    Lunardini, Cecilia; Sabancilar, Eray; Yang, Lili E-mail: Eray.Sabancilar@asu.edu

    2013-08-01

    We study absorption of ultra high energy neutrinos by the cosmic neutrino background, with full inclusion of the effect of the thermal distribution of the background on the resonant annihilation channel. For a hierarchical neutrino mass spectrum (with at least one neutrino with mass below ∼ 10{sup −2} eV), thermal effects are important for ultra high energy neutrino sources at z∼>16. The neutrino transmission probability shows no more than two separate suppression dips since the two lightest mass eigenstates contribute as a single species when thermal effects are included. Results are applied to a number of models of ultra high energy neutrino emission. Suppression effects are strong for sources that extend beyond z ∼ 10, which can be realized for certain top down scenarios, such as superheavy dark matter decays, cosmic strings and cosmic necklaces. For these, a broad suppression valley should affect the neutrino spectrum at least in the energy interval 10{sup 12}−10{sup 13} GeV — which therefore is disfavored for ultra high energy neutrino searches — with only a mild dependence on the neutrino mass spectrum and hierarchy. The observation of absorption effects would indicate a population of sources beyond z ∼ 10, and favor top-down mechanisms; it would also be an interesting probe of the physics of the relic neutrino background in the unexplored redshift interval z ∼ 10–100.

  19. Fractal morphology of black carbon aerosol enhances absorption in the thermal infrared wavelengths.

    PubMed

    Heinson, William R; Chakrabarty, Rajan K

    2016-02-15

    In this Letter, we numerically calculate the mass absorption cross sections (MACs) of black carbon fractal aggregates in the thermal infrared solar spectrum. Compared to equivalent-size spheres, the MAC values of aggregates show a percent enhancement of ≈150 and 400 at small and large length scales, respectively. The absorption properties of aggregates with size parameters >1 surprisingly continued to remain in the Rayleigh optics regime. We explain this phenomenon using the Maxwell-Garnett effective medium theory and the concept of phase shift parameter. PMID:26872194

  20. Theoretical model of homogeneous metal-insulator-metal perfect multi-band absorbers for the visible spectrum

    NASA Astrophysics Data System (ADS)

    Kajtár, G.; Kafesaki, M.; Economou, E. N.; Soukoulis, C. M.

    2016-02-01

    We present a rigorous study of the perfect absorption properties of metal-insulator-metal (MIM) structures in the visible spectrum. We provide a derivation (based on the transfer matrix method) and analysis of the conditions for which the perfect absorption occurs. We show that these conditions are fulfilled when the incident wave excites the eigenmodes of the structure. The quantitative analysis allows us to design specific perfect absorbers for our needs. The analytical model is verified by rigorous simulations based on rigorous coupled wave analysis, which demonstrate also the angle and polarization insensitivity of the absorption properties of such a structure. Employing the MIM approach and results, we also investigate and demonstrate multiple perfect absorption bands and broad-band absorption in properly designed multilayer metal-insulator systems.

  1. 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.

  2. Absorption Characteristics of Vertebrate Non-Visual Opsin, Opn3.

    PubMed

    Sugihara, Tomohiro; Nagata, Takashi; Mason, Benjamin; Koyanagi, Mitsumasa; Terakita, Akihisa

    2016-01-01

    Most animals possess multiple opsins which sense light for visual and non-visual functions. Here, we show spectral characteristics of non-visual opsins, vertebrate Opn3s, which are widely distributed among vertebrates. We successfully expressed zebrafish Opn3 in mammalian cultured cells and measured its absorption spectrum spectroscopically. When incubated with 11-cis retinal, zebrafish Opn3 formed a blue-sensitive photopigment with an absorption maximum around 465 nm. The Opn3 converts to an all-trans retinal-bearing photoproduct with an absorption spectrum similar to the dark state following brief blue-light irradiation. The photoproduct experienced a remarkable blue-shift, with changes in position of the isosbestic point, during further irradiation. We then used a cAMP-dependent luciferase reporter assay to investigate light-dependent cAMP responses in cultured cells expressing zebrafish, pufferfish, anole and chicken Opn3. The wild type opsins did not produce responses, but cells expressing chimera mutants (WT Opn3s in which the third intracellular loops were replaced with the third intracellular loop of a Gs-coupled jellyfish opsin) displayed light-dependent changes in cAMP. The results suggest that Opn3 is capable of activating G protein(s) in a light-dependent manner. Finally, we used this assay to measure the relative wavelength-dependent response of cells expressing Opn3 chimeras to multiple quantally-matched stimuli. The inferred spectral sensitivity curve of zebrafish Opn3 accurately matched the measured absorption spectrum. We were unable to estimate the spectral sensitivity curve of mouse or anole Opn3, but, like zebrafish Opn3, the chicken and pufferfish Opn3-JiL3 chimeras also formed blue-sensitive pigments. These findings suggest that vertebrate Opn3s may form blue-sensitive G protein-coupled pigments. Further, we suggest that the method described here, combining a cAMP-dependent luciferase reporter assay with chimeric opsins possessing the third

  3. Absorption Characteristics of Vertebrate Non-Visual Opsin, Opn3

    PubMed Central

    Sugihara, Tomohiro; Nagata, Takashi; Mason, Benjamin; Koyanagi, Mitsumasa; Terakita, Akihisa

    2016-01-01

    Most animals possess multiple opsins which sense light for visual and non-visual functions. Here, we show spectral characteristics of non-visual opsins, vertebrate Opn3s, which are widely distributed among vertebrates. We successfully expressed zebrafish Opn3 in mammalian cultured cells and measured its absorption spectrum spectroscopically. When incubated with 11-cis retinal, zebrafish Opn3 formed a blue-sensitive photopigment with an absorption maximum around 465 nm. The Opn3 converts to an all-trans retinal-bearing photoproduct with an absorption spectrum similar to the dark state following brief blue-light irradiation. The photoproduct experienced a remarkable blue-shift, with changes in position of the isosbestic point, during further irradiation. We then used a cAMP-dependent luciferase reporter assay to investigate light-dependent cAMP responses in cultured cells expressing zebrafish, pufferfish, anole and chicken Opn3. The wild type opsins did not produce responses, but cells expressing chimera mutants (WT Opn3s in which the third intracellular loops were replaced with the third intracellular loop of a Gs-coupled jellyfish opsin) displayed light-dependent changes in cAMP. The results suggest that Opn3 is capable of activating G protein(s) in a light-dependent manner. Finally, we used this assay to measure the relative wavelength-dependent response of cells expressing Opn3 chimeras to multiple quantally-matched stimuli. The inferred spectral sensitivity curve of zebrafish Opn3 accurately matched the measured absorption spectrum. We were unable to estimate the spectral sensitivity curve of mouse or anole Opn3, but, like zebrafish Opn3, the chicken and pufferfish Opn3-JiL3 chimeras also formed blue-sensitive pigments. These findings suggest that vertebrate Opn3s may form blue-sensitive G protein-coupled pigments. Further, we suggest that the method described here, combining a cAMP-dependent luciferase reporter assay with chimeric opsins possessing the third

  4. THE 3 μm SPECTRUM OF JUPITER's IRREGULAR SATELLITE HIMALIA

    SciTech Connect

    Brown, M. E.; Rhoden, A. R. E-mail: Alyssa.Rhoden@jhuapl.edu

    2014-10-01

    We present a medium resolution spectrum of Jupiter's irregular satellite Himalia covering the critical 3 μm spectral region. The spectrum shows no evidence for aqueously altered phyllosilicates, as had been suggested from the tentative detection of a 0.7 μm absorption, but instead shows a spectrum strikingly similar to the C/CF type asteroid 52 Europa. 52 Europa is the prototype of a class of asteroids generally situated in the outer asteroid belt between less distant asteroids which show evidence for aqueous alteration and more distant asteroids which show evidence for water ice. The spectral match between Himalia and this group of asteroids is surprising and difficult to reconcile with models of the origin of the irregular satellites.

  5. Vaginal Absorption of Penicillin.

    PubMed

    Rock, J; Barker, R H; Bacon, W B

    1947-01-01

    Except during the last two months of pregnancy, penicillin is easily absorbed from cocoa butter suppositories in the vagina, ordinarily to give therapeutic blood levels for from 4 to 6 hours. Penicillin in the dosage used seems to have a good effect on vaginal infections. In nonpregnant women, during the ovulation phase, considered as including days 14 +/- 2 in the ordinary menstrual cycle of about 28 days, absorption seemed to be somewhat diminished. Higher levels were found in patients who were near the end of their menstrual cycles and in two patients who were menopausal. Patients who were very near term absorbed little or no penicillin, whereas patients 10 days post partum showed excellent absorption.

  6. Demonstrating Absorption Spectra Using Commercially Available Incandescent Light Bulbs

    NASA Astrophysics Data System (ADS)

    Birriel, Jennifer J.

    In introductory astronomy courses, I typically introduce the three types of spectra: continuous, absorption line, and emission line. It is standard practice to use an ordinary incandescent light bulb to demonstrate the production of a continuous spectrum, and gas discharge tubes to demonstrate the production of an emission line spectrum. The concept of an absorption spectrum is more difficult for students to grasp. A variety of commercially available light bulbs can be used to demonstrate absorption spectra. Here I discuss the use of specialty incandescent light bulbs to demonstrate the phenomenon of absorption of the continuous spectrum produced by a hot tungsten filament. The bulbs examined include the GE Reveal bulb, yellow anti-insect lights, colored party bulbs, and an incandescent "black light" bulb. The bulbs can be used in a lecture or laboratory setting.

  7. [Denoising and assessing method of additive noise in the ultraviolet spectrum of SO2 in flue gas].

    PubMed

    Zhou, Tao; Sun, Chang-Ku; Liu, Bin; Zhao, Yu-Mei

    2009-11-01

    The problem of denoising and assessing method of the spectrum of SO2 in flue gas was studied based on DOAS. The denoising procedure of the additive noise in the spectrum was divided into two parts: reducing the additive noise and enhancing the useful signal. When obtaining the absorption feature of measured gas, a multi-resolution preprocessing method of original spectrum was adopted for denoising by DWT (discrete wavelet transform). The signal energy operators in different scales were used to choose the denoising threshold and separate the useful signal from the noise. On the other hand, because there was no sudden change in the spectra of flue gas in time series, the useful signal component was enhanced according to the signal time dependence. And the standard absorption cross section was used to build the ideal absorption spectrum with the measured gas temperature and pressure. This ideal spectrum was used as the desired signal instead of the original spectrum in the assessing method to modify the SNR (signal-noise ratio). There were two different environments to do the proof test-in the lab and at the scene. In the lab, SO2 was measured several times with the system using this method mentioned above. The average deviation was less than 1.5%, while the repeatability was less than 1%. And the short range experiment data were better than the large range. In the scene of a power plant whose concentration of flue gas had a large variation range, the maximum deviation of this method was 2.31% in the 18 groups of contrast data. The experimental results show that the denoising effect of the scene spectrum was better than that of the lab spectrum. This means that this method can improve the SNR of the spectrum effectively, which is seriously polluted by additive noise. PMID:20101989

  8. Calculated Hanle transmission and absorption spectra of the {sup 87}Rb D{sub 1} line with residual magnetic field for arbitrarily polarized light

    SciTech Connect

    Noh, Heung-Ryoul; Moon, Han Seb

    2010-09-15

    This paper reports a theoretical study on the transmission spectra of an arbitrarily polarized laser beam through a rubidium cell with or without a buffer gas in Hanle-type coherent population trapping (CPT). This study examined how laser polarization, transverse magnetic field, and collisions with buffer gas affects the spectrum. The transmission spectrum due to CPT and the absorption spectrum due to the level crossing absorption (LCA) were calculated according to the laser polarization. The results show that the LCA is strongly dependent on the transverse magnetic field and interaction time of the atoms with a laser light via collisions with the buffer gas. In addition, the spectral shape of the calculated Hanle spectrum is closely related to the direction between the (stray) transverse magnetic field and polarization of the laser.

  9. Studying Velocity Turbulence from Doppler-broadened Absorption Lines: Statistics of Optical Depth Fluctuations

    SciTech Connect

    Lazarian, A.; Pogosyan, D.

    2008-10-10

    We continue our work on developing techniques for studying turbulence with spectroscopic data. We show that Doppler-broadened absorption spectral lines, in particular, saturated absorption lines, can be used within the framework of the previously introduced technique termed the velocity coordinate spectrum (VCS). The VCS relates the statistics of fluctuations along the velocity coordinate to the statistics of turbulence; thus, it does not require spatial coverage by sampling directions in the plane of the sky. We consider lines with different degree of absorption and show that for lines of optical depth less than one, our earlier treatment of the VCS developed for spectral emission lines is applicable, if the optical depth is used instead of intensity. This amounts to correlating the logarithms of absorbed intensities. For larger optical depths and saturated absorption lines, we show that only wings of the line are available for the analysis. In terms of the VCS formalism, this results in introducing an additional window, whose size decreases with the increase of the optical depth. As a result, strongly saturated absorption lines only carry the information about the small-scale turbulence. Nevertheless, the contrast of the fluctuations corresponding to the small-scale turbulence increases with the increase of the optical depth, which provides advantages for studying turbulence by combining lines with different optical depths. By combining different absorption lines one can develop a tomography of the turbulence in the interstellar gas in all its complexity.

  10. Light absorption measurements: new techniques.

    PubMed

    Hänel, G; Busen, R; Hillenbrand, C; Schloss, R

    1982-02-01

    A new radiometer is described which simplifies measurement of the radiation supply of solar wavelengths. Two methods of measuring the radiant energy absorbed by aerosol particles are described: A photometric technique is used for particles collected on filters, and a calorimetric technique is used for in situ measurements. Data collected with the radiometer and the light absorption techniques yield the heating rate of the atmosphere due to light absorption by the particles. Sample measurements show substantial atmospheric temperature increases due to absorption, especially in industrial regions.

  11. The action spectrum for vitamin D3: initial skin reaction and prolonged exposure.

    PubMed

    van Dijk, Arjan; den Outer, Peter; van Kranen, Henk; Slaper, Harry

    2016-07-01

    Vitamin D3 photosynthesis in the skin is formulated as a set of reaction equations, including side-reactions to lumisterol, tachysterol and toxisterols, and the accompanying reverse reactions, isomerisation of previtamin D3 to vitamin D3 and photodegradation of vitamin D3. The solution of this set is given for the stationary irradiance spectrum. The effective action spectrum for the instantaneous vitamin D3 production changes shape as a function of exposure, and therefore, no single action spectrum can be used. We assessed the action spectrum for unexposed skin and for skin that has been exposed to 7.5 Standard Erythemal Doses (SED). We constructed two new estimates: (1) the RIVM action spectrum, based on absorption spectra, quantum yields and skin transmission spectra, and (2) the modified QUT action spectrum, which is adjusted for self-absorption and skin transmission. For previously unexposed skin, the modified QUT action spectrum gives a qualitatively similar, but larger estimate than the RIVM action spectrum. We have not been able to solve the lack of quantitative agreement between the vitamin D production estimates from the three action spectrum estimates (RIVM, modified QUT and CIE). All new action spectra have stronger emphasis on the short wavelengths than the CIE action spectrum. We showed that, for wavelengths larger than 300 nm, the bandwidth that was used in the experiment that formed the basis of the CIE action spectrum, gives a red-shift of about 1 nm. Generally, with the formation of previtamin D3, the return reaction to provitamin D3 limits the production of vitamin D3. After some exposure, the new action spectrum has negative values for the longer wavelengths in the UVB. For the RIVM action spectrum, this happens after 7.5 SED, for the modified QUT action spectrum already after 1.25 SED, and after 7.5 SED the net production rate is largely cancelled. Thus prolonged exposure of previously unexposed skin saturates vitamin D3 formation. For maximum

  12. Effects of backlight structure on absorption experiments

    SciTech Connect

    Iglesias, C A

    2004-11-08

    The impact of spectral details in the backlight of absorption spectroscopy experiments is considered. It is shown that experimentally unresolved structure in the backlight spectrum can introduce significant errors in the inferred transmission. Furthermore, it is shown that a valuable experimental procedure previously used to test the accuracy of the data fails to reveal these errors.

  13. THE TRANSIT TRANSMISSION SPECTRUM OF A COLD GAS GIANT PLANET

    SciTech Connect

    Dalba, Paul A.; Muirhead, Philip S.; Veyette, Mark J.; Fortney, Jonathan J.; Hedman, Matthew M.; Nicholson, Philip D.

    2015-12-01

    We use solar occultations observed by the Visual and Infrared Mapping Spectrometer on board the Cassini Spacecraft to extract the 1–5 μm transmission spectrum of Saturn, as if it were a transiting exoplanet. We detect absorption from methane, ethane, acetylene, aliphatic hydrocarbons, and possibly carbon monoxide, with peak-to-peak features of up to 90 parts-per-million despite the presence of ammonia clouds. We also find that atmospheric refraction, as opposed to clouds or haze, determines the minimum altitude that could be probed during mid-transit. Self-consistent exoplanet atmosphere models show good agreement with Saturn’s transmission spectrum but fail to reproduce a large absorption feature near 3.4 μm, likely caused by gaseous ethane and a C–H stretching mode of an unknown aliphatic hydrocarbon. This large feature is located in one of the Spitzer Space Telescope bandpasses and could alter interpretations of transmission spectra if not properly modeled. The large signal in Saturn’s transmission spectrum suggests that transmission spectroscopy of cold, long-period gaseous exoplanets should be possible with current and future observatories. Motivated by these results, we briefly consider the feasibility of  using a survey to search for and characterize cold exoplanets that are analogous to Jupiter and Saturn utilizing a target-of-opportunity approach.

  14. The Transit Transmission Spectrum of a Cold Gas Giant Planet

    NASA Astrophysics Data System (ADS)

    Dalba, Paul A.; Muirhead, Philip S.; Fortney, Jonathan J.; Hedman, Matthew M.; Nicholson, Philip D.; Veyette, Mark J.

    2015-12-01

    We use solar occultations observed by the Visual and Infrared Mapping Spectrometer on board the Cassini Spacecraft to extract the 1-5 μm transmission spectrum of Saturn, as if it were a transiting exoplanet. We detect absorption from methane, ethane, acetylene, aliphatic hydrocarbons, and possibly carbon monoxide, with peak-to-peak features of up to 90 parts-per-million despite the presence of ammonia clouds. We also find that atmospheric refraction, as opposed to clouds or haze, determines the minimum altitude that could be probed during mid-transit. Self-consistent exoplanet atmosphere models show good agreement with Saturn’s transmission spectrum but fail to reproduce a large absorption feature near 3.4 μm, likely caused by gaseous ethane and a C-H stretching mode of an unknown aliphatic hydrocarbon. This large feature is located in one of the Spitzer Space Telescope bandpasses and could alter interpretations of transmission spectra if not properly modeled. The large signal in Saturn’s transmission spectrum suggests that transmission spectroscopy of cold, long-period gaseous exoplanets should be possible with current and future observatories. Motivated by these results, we briefly consider the feasibility of using a survey to search for and characterize cold exoplanets that are analogous to Jupiter and Saturn utilizing a target-of-opportunity approach.

  15. Self-absorption of tritium betas in metal tritide particles.

    PubMed

    Kropf, R F; Wang, Y; Cheng, Y S

    1998-10-01

    Inhaling metal tritide particles is a potential occupational hazard. The radiation dose to tissue from tritide particles depends on their solubility and retention in the body. In each tritide particle, a portion of the beta particles from decay of tritium is absorbed by the metal matrix and therefore cannot contribute to absorbed radiation dose to tissue. A theoretical model for estimating the self-absorption of tritium betas in spherical metal tritide particles is presented. Numerical calculations are made with this method for titanium, zirconium, and erbium particles from 0.5 to 50 microm in diameter. The tritium spectrum is divided into energy groups to facilitate estimation of the energy that escapes the particle for dose calculations. Our results show considerable absorption of beta particles and their energy, even for respirable particles smaller than 5 microm. Limited experimental data of self-absorption for titanium and zirconium tritides supported the theoretical calculation. It is concluded that the self-absorption factors should be required for counting tritide particle samples as well as for estimating absorbed radiation dose to tissue. PMID:9753363

  16. Absorption of ac fields in amorphous indium-oxide films

    SciTech Connect

    Ovadyahu, Z.

    2014-08-20

    Absorption data from applied ac fields in Anderson-localized amorphous indium-oxide (In{sub x}O) films are shown to be frequency and disorder dependent. The absorption shows a roll-off at a frequency which is much lower than the electron-electron scattering rate of the material when it is in the diffusive regime. This is interpreted as evidence for discreteness of the energy spectrum of the deeply localized regime. This is consistent with recent many-body localization scenarios. As the metal-insulator transition is approached, the absorption shifts to higher frequencies. Comparing with the previously obtained results on the crystalline version of indium-oxide (In{sub 2}O{sub 3−x}) implies a considerably higher inelastic electron-phonon scattering rate in the amorphous material. The range over which the absorption versus frequency decreases may indicate that a wide distribution of localization length is a common feature in these systems.

  17. Optical absorption of dilute nitride alloys using self-consistent Green’s function method

    PubMed Central

    2014-01-01

    We have calculated the optical absorption for InGaNAs and GaNSb using the band anticrossing (BAC) model and a self-consistent Green’s function (SCGF) method. In the BAC model, we include the interaction of isolated and pair N levels with the host matrix conduction and valence bands. In the SCGF approach, we include a full distribution of N states, with non-parabolic conduction and light-hole bands, and parabolic heavy-hole and spin-split-off bands. The comparison with experiments shows that the first model accounts for many features of the absorption spectrum in InGaNAs; including the full distribution of N states improves this agreement. Our calculated absorption spectra for GaNSb alloys predict the band edges correctly but show more features than are seen experimentally. This suggests the presence of more disorder in GaNSb alloys in comparison with InGaNAs. PMID:24475947

  18. Autism Spectrum Disorder (ASD): Related Topics

    MedlinePlus

    ... Facebook Tweet Share Compartir Q: Do vaccines cause autism spectrum disorder (ASD)? A: Many studies that have looked at whether there is a relationship between vaccines and autism spectrum disorder (ASD). To date, the studies continue to show ...

  19. Full wave effects on the lower hybrid wave spectrum and driven current profile in tokamak plasmas

    SciTech Connect

    Shiraiwa, S.; Ko, J.; Meneghini, O.; Parker, R.; Schmidt, A. E.; Greenwald, M.; Hubbard, A. E.; Hughes, J.; Ma, Y.; Podpaly, Y.; Rice, J. E.; Wallace, G.; Wolfe, S. M.; C-Mod Group, Alcator; Scott, S.; Wilson, J. R.

    2011-08-15

    A numerical modeling of current profile modification by lower hybrid current drive (LHCD) using a fullwave/Fokker-Planck simulation code is presented. A MHD stable LHCD discharge on Alcator C-Mod was analyzed, and the current profile from full wave simulations was found to show better agreement with the experiment than a ray-tracing code. Comparison of full wave and ray-tracing simulation shows that, although ray-tracing can reproduce the stochastic wave spectrum broadening, the full wave calculation predicts even wider spectrum broadening, and the wave spectrum fills all of the kinematically allowed domain. This is the first demonstration of LHCD current profile modeling using a full wave simulation code in a multi-pass absorption regime, showing the clear impact of full wave effects on the LHCD driven current profile.

  20. The spatio-temporal spectrum of turbulent flows.

    PubMed

    Clark di Leoni, P; Cobelli, P J; Mininni, P D

    2015-12-01

    Identification and extraction of vortical structures and of waves in a disorganised flow is a mayor challenge in the study of turbulence. We present a study of the spatio-temporal behavior of turbulent flows in the presence of different restitutive forces. We show how to compute and analyse the spatio-temporal spectrum from data stemming from numerical simulations and from laboratory experiments. Four cases are considered: homogeneous and isotropic turbulence, rotating turbulence, stratified turbulence, and water wave turbulence. For homogeneous and isotropic turbulence, the spectrum allows identification of sweeping by the large-scale flow. For rotating and for stratified turbulence, the spectrum allows identification of the waves, precise quantification of the energy in the waves and in the turbulent eddies, and identification of physical mechanisms such as Doppler shift and wave absorption in critical layers. Finally, in water wave turbulence the spectrum shows a transition from gravity-capillary waves to bound waves as the amplitude of the forcing is increased. PMID:26701711

  1. The spatio-temporal spectrum of turbulent flows.

    PubMed

    Clark di Leoni, P; Cobelli, P J; Mininni, P D

    2015-12-01

    Identification and extraction of vortical structures and of waves in a disorganised flow is a mayor challenge in the study of turbulence. We present a study of the spatio-temporal behavior of turbulent flows in the presence of different restitutive forces. We show how to compute and analyse the spatio-temporal spectrum from data stemming from numerical simulations and from laboratory experiments. Four cases are considered: homogeneous and isotropic turbulence, rotating turbulence, stratified turbulence, and water wave turbulence. For homogeneous and isotropic turbulence, the spectrum allows identification of sweeping by the large-scale flow. For rotating and for stratified turbulence, the spectrum allows identification of the waves, precise quantification of the energy in the waves and in the turbulent eddies, and identification of physical mechanisms such as Doppler shift and wave absorption in critical layers. Finally, in water wave turbulence the spectrum shows a transition from gravity-capillary waves to bound waves as the amplitude of the forcing is increased.

  2. [Study on Differential Optical Absorption Spectroscopy Data Processing Based on Chirp-Z Transformation].

    PubMed

    Zheng, Hai-ming; Li, Guang-jie; Wu, Hao

    2015-06-01

    Differential optical absorption spectroscopy (DOAS) is a commonly used atmospheric pollution monitoring method. Denoising of monitoring spectral data will improve the inversion accuracy. Fourier transform filtering method is effectively capable of filtering out the noise in the spectral data. But the algorithm itself can introduce errors. In this paper, a chirp-z transform method is put forward. By means of the local thinning of Fourier transform spectrum, it can retain the denoising effect of Fourier transform and compensate the error of the algorithm, which will further improve the inversion accuracy. The paper study on the concentration retrieving of SO2 and NO2. The results show that simple division causes bigger error and is not very stable. Chirp-z transform is proved to be more accurate than Fourier transform. Results of the frequency spectrum analysis show that Fourier transform cannot solve the distortion and weakening problems of characteristic absorption spectrum. Chirp-z transform shows ability in fine refactoring of specific frequency spectrum.

  3. [Study on Differential Optical Absorption Spectroscopy Data Processing Based on Chirp-Z Transformation].

    PubMed

    Zheng, Hai-ming; Li, Guang-jie; Wu, Hao

    2015-06-01

    Differential optical absorption spectroscopy (DOAS) is a commonly used atmospheric pollution monitoring method. Denoising of monitoring spectral data will improve the inversion accuracy. Fourier transform filtering method is effectively capable of filtering out the noise in the spectral data. But the algorithm itself can introduce errors. In this paper, a chirp-z transform method is put forward. By means of the local thinning of Fourier transform spectrum, it can retain the denoising effect of Fourier transform and compensate the error of the algorithm, which will further improve the inversion accuracy. The paper study on the concentration retrieving of SO2 and NO2. The results show that simple division causes bigger error and is not very stable. Chirp-z transform is proved to be more accurate than Fourier transform. Results of the frequency spectrum analysis show that Fourier transform cannot solve the distortion and weakening problems of characteristic absorption spectrum. Chirp-z transform shows ability in fine refactoring of specific frequency spectrum. PMID:26601381

  4. The spectrum character of photoreaction of Hypocrellin A and cysteine

    NASA Astrophysics Data System (ADS)

    Zhang, Jucheng; Liu, Wei; Li, Ying; Zhang, Pei; Yi, Zhongzhou; Min, Yong; Huang, Zhaolong; Yao, Lihua; Lu, Haiju

    2008-12-01

    In the current work, Hypocrellin A (HA) is one of the nature photosensitizer was recognized by researchers, and it used as a probe to research the molecular recognition and interaction with protein, the work suggested the HA can as the medicine to treat some disease. This paper study the spectrum character of photoreaction of Hypocrellin A and cysteine in different pH value, the spectrum show an isosbestic point at 495nm, and the absorption peak at 478nm was red-shifted to about 500nm. The result suggested the HA can react with cysteine in this condition, and farther illuminated the cysteine residue may is one of the target of the interaction of HA or HB with protein.

  5. Two-dimensional probe absorption in coupled quantum dots

    NASA Astrophysics Data System (ADS)

    Liu, Ningwu; Zhang, Yan; Kang, Chengxian; Wang, Zhiping; Yu, Benli

    2016-07-01

    We investigate the two-dimensional (2D) probe absorption in coupled quantum dots. It is found that, due to the position-dependent quantum interference effect, the 2D optical absorption spectrum can be easily controlled via adjusting the system parameters. Thus, our scheme may provide some technological applications in solid-state quantum communication.

  6. Television Quiz Show Simulation

    ERIC Educational Resources Information Center

    Hill, Jonnie Lynn

    2007-01-01

    This article explores the simulation of four television quiz shows for students in China studying English as a foreign language (EFL). It discusses the adaptation and implementation of television quiz shows and how the students reacted to them.

  7. [The spectrum characteristics of an invasion plant: Eupatorium adenophorum Spreng].

    PubMed

    Chen, Jun; Quan, Wen-ting; Zhou, Guan-hua; Wen, Zhen-he

    2010-07-01

    Eupatorium adenophorum Spreng. (EAS) is a toxic invasion plant and has caused significant economic and environmental impacts in China. The EAS has the characteristics of widely distributing and quickly spreading. The traditional detecting and supervising methods become invalid when applied for managing the spatial distribution of EAS. Based on the analyzing results of the spectrum features of EAS, the present paper tried to structure the identifying models by remote sensing. The main objective of this paper is to develop an available method for detecting and mapping the spatial distribution of EAS. The study shows that the spectrum of EAS has two reflecting peaks and one absorbing trough. The corresponding wavelengths of those peaks are 560, 730 and 674 nm, respectively. The absorption characteristics of EAS at 647 nm are that the absorbing depth is 0.504 3-1.910 3, the absorbing width is 13.778 9-17.251 8 nm and the area at the left absorption band is greater than the right, and the corresponding area ratio of left to right is 1.771 9-2.444 1. The white flowers of EAS make the reflectance higher at visible bands, and the first-order derivatives of EAS spectral show a wave peak at 420 nm. Compared with the spectral feature of other representative materials, the absorbing characteristics at 647 nm, such as absorption width and absorption depth, and the peak at 420 nm of derivatives spectral are special features of EAS spectral, which can be used as remotely sensed parameters for detecting and mapping the EAS at florescence. PMID:20827985

  8. Multi-domain electromagnetic absorption of triangular quantum rings

    NASA Astrophysics Data System (ADS)

    Sitek, Anna; Thorgilsson, Gunnar; Gudmundsson, Vidar; Manolescu, Andrei

    2016-06-01

    We present a theoretical study of the unielectronic energy spectra, electron localization, and optical absorption of triangular core–shell quantum rings. We show how these properties depend on geometric details of the triangle, such as side thickness or corners’ symmetry. For equilateral triangles, the lowest six energy states (including spin) are grouped in an energy shell, are localized only around corner areas, and are separated by a large energy gap from the states with higher energy which are localized on the sides of the triangle. The energy levels strongly depend on the aspect ratio of the triangle sides, i.e., thickness/length ratio, in such a way that the energy differences are not monotonous functions of this ratio. In particular, the energy gap between the group of states localized in corners and the states localized on the sides strongly decreases with increasing the side thickness, and then slightly increases for thicker samples. With increasing the thickness the low-energy shell remains distinct but the spatial distribution of these states spreads. The behavior of the energy levels and localization leads to a thickness-dependent absorption spectrum where one transition may be tuned in the THz domain and a second transition can be tuned from THz to the infrared range of electromagnetic spectrum. We show how these features may be further controlled with an external magnetic field. In this work the electron–electron Coulomb repulsion is neglected.

  9. Multi-domain electromagnetic absorption of triangular quantum rings

    NASA Astrophysics Data System (ADS)

    Sitek, Anna; Thorgilsson, Gunnar; Gudmundsson, Vidar; Manolescu, Andrei

    2016-06-01

    We present a theoretical study of the unielectronic energy spectra, electron localization, and optical absorption of triangular core-shell quantum rings. We show how these properties depend on geometric details of the triangle, such as side thickness or corners’ symmetry. For equilateral triangles, the lowest six energy states (including spin) are grouped in an energy shell, are localized only around corner areas, and are separated by a large energy gap from the states with higher energy which are localized on the sides of the triangle. The energy levels strongly depend on the aspect ratio of the triangle sides, i.e., thickness/length ratio, in such a way that the energy differences are not monotonous functions of this ratio. In particular, the energy gap between the group of states localized in corners and the states localized on the sides strongly decreases with increasing the side thickness, and then slightly increases for thicker samples. With increasing the thickness the low-energy shell remains distinct but the spatial distribution of these states spreads. The behavior of the energy levels and localization leads to a thickness-dependent absorption spectrum where one transition may be tuned in the THz domain and a second transition can be tuned from THz to the infrared range of electromagnetic spectrum. We show how these features may be further controlled with an external magnetic field. In this work the electron-electron Coulomb repulsion is neglected.

  10. Multi-domain electromagnetic absorption of triangular quantum rings.

    PubMed

    Sitek, Anna; Thorgilsson, Gunnar; Gudmundsson, Vidar; Manolescu, Andrei

    2016-06-01

    We present a theoretical study of the unielectronic energy spectra, electron localization, and optical absorption of triangular core-shell quantum rings. We show how these properties depend on geometric details of the triangle, such as side thickness or corners' symmetry. For equilateral triangles, the lowest six energy states (including spin) are grouped in an energy shell, are localized only around corner areas, and are separated by a large energy gap from the states with higher energy which are localized on the sides of the triangle. The energy levels strongly depend on the aspect ratio of the triangle sides, i.e., thickness/length ratio, in such a way that the energy differences are not monotonous functions of this ratio. In particular, the energy gap between the group of states localized in corners and the states localized on the sides strongly decreases with increasing the side thickness, and then slightly increases for thicker samples. With increasing the thickness the low-energy shell remains distinct but the spatial distribution of these states spreads. The behavior of the energy levels and localization leads to a thickness-dependent absorption spectrum where one transition may be tuned in the THz domain and a second transition can be tuned from THz to the infrared range of electromagnetic spectrum. We show how these features may be further controlled with an external magnetic field. In this work the electron-electron Coulomb repulsion is neglected.

  11. Multi-domain electromagnetic absorption of triangular quantum rings.

    PubMed

    Sitek, Anna; Thorgilsson, Gunnar; Gudmundsson, Vidar; Manolescu, Andrei

    2016-06-01

    We present a theoretical study of the unielectronic energy spectra, electron localization, and optical absorption of triangular core-shell quantum rings. We show how these properties depend on geometric details of the triangle, such as side thickness or corners' symmetry. For equilateral triangles, the lowest six energy states (including spin) are grouped in an energy shell, are localized only around corner areas, and are separated by a large energy gap from the states with higher energy which are localized on the sides of the triangle. The energy levels strongly depend on the aspect ratio of the triangle sides, i.e., thickness/length ratio, in such a way that the energy differences are not monotonous functions of this ratio. In particular, the energy gap between the group of states localized in corners and the states localized on the sides strongly decreases with increasing the side thickness, and then slightly increases for thicker samples. With increasing the thickness the low-energy shell remains distinct but the spatial distribution of these states spreads. The behavior of the energy levels and localization leads to a thickness-dependent absorption spectrum where one transition may be tuned in the THz domain and a second transition can be tuned from THz to the infrared range of electromagnetic spectrum. We show how these features may be further controlled with an external magnetic field. In this work the electron-electron Coulomb repulsion is neglected. PMID:27102909

  12. Incomplete intestinal absorption of fructose.

    PubMed

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

    1984-08-01

    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.

  13. 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

  14. Effective absorption in cladding-pumped fibers

    NASA Astrophysics Data System (ADS)

    Zervas, Michalis N.; Marshall, Andy; Kim, Jaesun

    2011-02-01

    We investigate experimentally and theoretically the wavelength dependence of the pump absorption along Yb3+-doped fibers, for cladding-pumped single as well as coupled multimode (GTWaveTM) fibers. We show that significant spectral absorption distortions occur along the length with the 976nm absorption peak affected the most. We have developed a novel theoretical approach, based on coupled mode theory, to explain the observed effects. We have also investigated the mode mixing requirements in order to improve the absorption spectral distribution along the increase the overall absorption efficiency and discuss the implications on fiber laser performance.

  15. Measurement of Gas and Aerosol Phase Absorption Spectra across the Visible and Near-IR Using Supercontinuum Photoacoustic Spectroscopy.

    PubMed

    Radney, James G; Zangmeister, Christopher D

    2015-07-21

    We demonstrate a method to measure the absorption spectra of gas and aerosol species across the visible and near-IR (500 to 840 nm) using a photoacoustic (PA) spectrometer and a pulsed supercontinuum laser source. Measurements of gas phase absorption spectra were demonstrated using H2O(g) as a function of relative humidity (RH). The measured absorption intensities and peak shapes were able to be quantified and compared to spectra calculated using the 2012 High Resolution Transmission (HITRAN2012) database. Size and mass selected nigrosin aerosol was used to measure absorption spectra across the visible and near-IR. Spectra were measured as a function of aerosol size/mass and show good agreement to Mie theory calculations. Lastly, we measured the broadband absorption spectrum of flame generated soot aerosol at 5% and 70% RH. For the high RH case, we are able to quantifiably separate the soot and water absorption contributions. For soot, we observe an enhancement in the mass specific absorption cross section ranging from 1.5 at 500 nm (p < 0.01) to 1.2 at 840 nm (p < 0.2) and a concomitant increase in the absorption Ångström exponent from 1.2 ± 0.4 (5% RH) to 1.6 ± 0.3 (70% RH). PMID:26098142

  16. ShowMe3D

    SciTech Connect

    Sinclair, Michael B

    2012-01-05

    ShowMe3D is a data visualization graphical user interface specifically designed for use with hyperspectral image obtained from the Hyperspectral Confocal Microscope. The program allows the user to select and display any single image from a three dimensional hyperspectral image stack. By moving a slider control, the user can easily move between images of the stack. The user can zoom into any region of the image. The user can select any pixel or region from the displayed image and display the fluorescence spectrum associated with that pixel or region. The user can define up to 3 spectral filters to apply to the hyperspectral image and view the image as it would appear from a filter-based confocal microscope. The user can also obtain statistics such as intensity average and variance from selected regions.

  17. ShowMe3D

    2012-01-05

    ShowMe3D is a data visualization graphical user interface specifically designed for use with hyperspectral image obtained from the Hyperspectral Confocal Microscope. The program allows the user to select and display any single image from a three dimensional hyperspectral image stack. By moving a slider control, the user can easily move between images of the stack. The user can zoom into any region of the image. The user can select any pixel or region from themore » displayed image and display the fluorescence spectrum associated with that pixel or region. The user can define up to 3 spectral filters to apply to the hyperspectral image and view the image as it would appear from a filter-based confocal microscope. The user can also obtain statistics such as intensity average and variance from selected regions.« less

  18. Identification and Characterization of Visible Absorption Components in Aqueous Methylglyoxal-Ammonium Sulfate Mixtures

    NASA Astrophysics Data System (ADS)

    McGivern, W. S.; Allison, T. C.; Radney, J. G.; Zangmeister, C. D.

    2014-12-01

    The aqueous reaction of methylglyoxal (MG) with ammonium sulfate has been suggested as a source of atmospheric ``brown carbon.'' We have utilized high-performance liquid chromatography coupled to ultraviolet-visible spectroscopy and tandem mass spectrometry to study the products of this reaction at high concentrations. The overall product spectrum shows a large number of distinct components; however, the visible absorption from this mixture is derived a very small number of components. The largest contributor is an imine-substituted (C=N-H) product of aldol condensation/facile dehydration reaction between the parent MG and a hydrated product of the MG + ammonia reaction. The asymmetric nature of this compound relative to the aldol condensation of two MG results in a sufficiently large redshift of the UV absorption spectrum that absorption of visible radiation can occur in the long-wavelength tail. The simplicity of the imine products is a result of a strong bias toward ketimine products due to the extensive hydration of the aldehydic moiety in the parent in aqueous solution. In addition, a strong pH dependence of the absorption cross section was observed with significantly greater absorption under more basic conditions. We have performed time-dependent density functional theory calculations to evaluate the absorption spectra of all of the possible condensation products and their respective ions, and the results are consistent with the experimental observations. We have also observed smaller concentrations of other condensation products of the imine-substituted parent species that do not contribute significantly to the visible absorption but have not been previously discussed.

  19. 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.

  20. 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.

  1. Autism Spectrum Disorder

    MedlinePlus

    ... Awards Enhancing Diversity Find People About NINDS NINDS Autism Spectrum Disorder Information Page Condensed from Autism Spectrum ... en Español Additional resources from MedlinePlus What is Autism Spectrum Disorder? Autistic disorder (sometimes called autism or ...

  2. 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

  3. Optical absorption signature of a self-assembled dye monolayer on graphene.

    PubMed

    Sghaier, Tessnim; Le Liepvre, Sylvain; Fiorini, Céline; Douillard, Ludovic; Charra, Fabrice

    2016-01-01

    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

  4. Variability of light absorption by aquatic particles in the near-infrared spectral region

    NASA Astrophysics Data System (ADS)

    Tassan, Stelvio; Ferrari, Giovanni M.

    2003-08-01

    We have measured the light absorption of a set of particle suspensions of varying nature (pure minerals, particulate standards, aquatic particles) using a double-beam spectrophotometer with a 15-cm-diameter integrating sphere. The sample was located inside the sphere so as to minimize the effect of light scattering by the particles. The results obtained showed highly variable absorption in the near-IR region of the wavelength spectrum. The same particle samples were deposited on glass-fiber filters, and their absorption was measured by the transmittance-reflectance method, based on a theoretical model that corrects for the effect of light scattering. The good agreement found between the results of the measurements carried out inside the sphere and by the transmittance-reflectance method confirms the validity of the scattering correction included in the above method.

  5. Deimos: A featureless asteroid-like spectrum

    NASA Technical Reports Server (NTRS)

    Grundy, W. M.; Fink, Uwe

    1991-01-01

    High quality CCD spectra were obtained of Deimos from 0.5 to 1.0 micron at a spectral resolution of 15A at the time of the 1988 Mars opposition. The data acquisition and reduction methods allowed the quantitative prevention of scattered light from Mars contaminating the spectra. Solar analog stars BS560, BS2007, and BS8931 were observed the same night to allow removal of telluric absorptions. The ratio spectrum of Deimos has a red slope, increasing in reflectance by a factor of approx. 50 pct. over the one octave wavelength interval observed. Other than this slope, the spectrum is remarkably featureless. The absence of absorption bands in the spectrum of Deimos is in marked contrast with the spectra of Martian surface materials. No trace of the Fe(2+) charge transfer absorption band around 1 micron is observed, which rules out the presence of significant quantities of minerals such as the pyroxenes or olivine at the surface of Deimos. The featureless red spectrum of Deimos appears to be consistent with a surface composition of fine grained carbonaceous chondrite type material. An analysis is presented of the spectrum of Deimos which makes use of the Hapke scattering surface model.

  6. A Holographic Road Show.

    ERIC Educational Resources Information Center

    Kirkpatrick, Larry D.; Rugheimer, Mac

    1979-01-01

    Describes the viewing sessions and the holograms of a holographic road show. The traveling exhibits, believed to stimulate interest in physics, include a wide variety of holograms and demonstrate several physical principles. (GA)

  7. Broad spectrum bioactive sunscreens.

    PubMed

    Velasco, Maria Valéria Robles; Sarruf, Fernanda Daud; Salgado-Santos, Idalina Maria Nunes; Haroutiounian-Filho, Carlos Alberto; Kaneko, Telma Mary; Baby, André Rolim

    2008-11-01

    The development of sunscreens containing reduced concentration of chemical UV filters, even though, possessing broad spectrum effectiveness with the use of natural raw materials that improve and infer UV absorption is of great interest. Due to the structural similarities between polyphenolic compounds and organic UV filters, they might exert photoprotection activity. The objective of the present research work was to develop bioactive sunscreen delivery systems containing rutin, Passiflora incarnata L. and Plantago lanceolata extracts associated or not with organic and inorganic UV filters. UV transmission of the sunscreen delivery system films was performed by using diffuse transmittance measurements coupling to an integrating sphere. In vitro photoprotection efficacy was evaluated according to the following parameters: estimated sun protection factor (SPF); Boot's Star Rating category; UVA/UVB ratio; and critical wavelength (lambda(c)). Sunscreen delivery systems obtained SPF values ranging from 0.972+/-0.004 to 28.064+/-2.429 and bioactive compounds interacted with the UV filters positive and negatively. This behavior may be attributed to: the composition of the delivery system; the presence of inorganic UV filter and quantitative composition of the organic UV filters; and the phytochemical composition of the P. incarnata L. and P. lanceolata extracts. Among all associations of bioactive compounds and UV filters, we found that the broad spectrum sunscreen was accomplished when 1.68% (w/w) P. incarnata L. dry extract was in the presence of 7.0% (w/w) ethylhexyl methoxycinnamate, 2.0% (w/w) benzophenone-3 and 2.0% (w/w) TiO(2). It was demonstrated that this association generated estimated SPF of 20.072+/-0.906 and it has improved the protective defense against UVA radiation accompanying augmentation of the UVA/UVB ratio from 0.49 to 0.52 and lambda(c) from 364 to 368.6nm. PMID:18662760

  8. Spectrum formation in superluminous supernovae (Type I)

    NASA Astrophysics Data System (ADS)

    Mazzali, P. A.; Sullivan, M.; Pian, E.; Greiner, J.; Kann, D. A.

    2016-06-01

    The near-maximum spectra of most superluminous supernovae (SLSNe) that are not dominated by interaction with a H-rich circum-stellar medium (SLSN-I) are characterized by a blue spectral peak and a series of absorption lines which have been identified as O II. SN 2011kl, associated with the ultra-long gamma-ray burst GRB111209A, also had a blue peak but a featureless optical/ultraviolet (UV) spectrum. Radiation transport methods are used to show that the spectra (not including SN 2007bi, which has a redder spectrum at peak, like ordinary SNe Ic) can be explained by a rather steep density distribution of the ejecta, whose composition appears to be typical of carbon-oxygen cores of massive stars which can have low metal content. If the photospheric velocity is ˜10 000-15 000 km s-1, several lines form in the UV. O II lines, however, arise from very highly excited lower levels, which require significant departures from local thermodynamic equilibrium to be populated. These SLSNe are not thought to be powered primarily by 56Ni decay. An appealing scenario is that they are energized by X-rays from the shock driven by a magnetar wind into the SN ejecta. The apparent lack of evolution of line velocity with time that characterizes SLSNe up to about maximum is another argument in favour of the magnetar scenario. The smooth UV continuum of SN 2011kl requires higher ejecta velocities (˜20 000 km s-1): line blanketing leads to an almost featureless spectrum. Helium is observed in some SLSNe after maximum. The high-ionization near-maximum implies that both He and H may be present but not observed at early times. The spectroscopic classification of SLSNe should probably reflect that of SNe Ib/c. Extensive time coverage is required for an accurate classification.

  9. 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).

  10. Observation of confinement effects through liner and nonlinear absorption spectroscopy in cuprous oxide

    NASA Astrophysics Data System (ADS)

    Sekhar, H.; Rakesh Kumar, Y.; Narayana Rao, D.

    2015-02-01

    Cuprous oxide nano clusters, micro cubes and micro particles were successfully synthesized by reducing copper (II) salt with ascorbic acid in the presence of sodium hydroxide via a co-precipitation method. The X-ray diffraction studies revealed the formation of pure single phase cubic. Raman spectrum shows the inevitable presence of CuO on the surface of the Cu2O powders which may have an impact on the stability of the phase. Transmission electron microscopy (TEM) data revealed that the morphology evolves from nanoclusters to micro cubes and micro particles by increasing the concentration of NaOH. Linear optical measurements show that the absorption peak maximum shifts towards red with changing morphology from nano clusters to micro cubes and micro particles. The nonlinear optical properties were studied using open aperture Z-scan technique with 532 nm, 6 ns laser pulses. Samples exhibited saturable as well as reverse saturable absorption. The results show that the transition from SA to RSA is ascribed to excited-state absorption (ESA) induced by two-photon absorption (TPA) process. Due to confinement effects (enhanced band gap) we observed enhanced nonlinear absorption coefficient (βeff) in the case of nano-clusters compared to their micro-cubes and micro-particles.

  11. Theoretical investigations of absorption and fluorescence spectra of protonated pyrene.

    PubMed

    Chin, Chih-Hao; Lin, Sheng Hsien

    2016-05-25

    The equilibrium geometry and 75 vibrational normal-mode frequencies of the ground and first excited states of protonated pyrene isomers were calculated and characterized in the adiabatic representation by using the complete active space self-consistent field (CASSCF) method. Electronic absorption spectra of solid neon matrixes in the wavelength range 495-415 nm were determined by Maier et al. and they were analyzed using time-dependent density functional theory calculations (TDDFT). CASSCF calculations and absorption and emission spectra simulations by one-photon excitation equations were used to optimize the excited and ground state structures of protonated pyrene isomers. The absorption band was attributed to the S0 → S1 electronic transition in 1H-Py(+), and a band origin was used at 20580.96 cm(-1). The displaced harmonic oscillator approximation and Franck-Condon approximation were used to simulate the absorption spectrum of the (1) (1)A' ← X[combining tilde](1)A' transition of 1H-Py(+), and the main vibronic transitions were assigned for the first ππ* state. It shows that the vibronic structures were dominated by one of the eight active totally symmetric modes, with ν15 being the most crucial. This indicates that the electronic transition of the S1((1)A') state calculated in the adiabatic representation effectively includes a contribution from the adiabatic vibronic coupling through Franck-Condon factors perturbed by harmonic oscillators. The present method can adequately reproduce experimental absorption and fluorescence spectra of a gas phase. PMID:27181017

  12. Double photoexcitation involving 2p and 4f electrons in L3 -edge x-ray absorption spectra of protactinium

    NASA Astrophysics Data System (ADS)

    Hennig, Christoph; Le Naour, Claire; Auwer, Christophe Den

    2008-06-01

    The L3 -edge x-ray absorption spectrum of Pa(V) fluoride in aqueous solution show clear evidence for the double photoexcitation involving 2p and 4f electrons. A comparison with the [2p4f] double-electron excitations observed in the L3 -edge x-ray absorption spectra of other actinides (thorium, uranium, neptunium, plutonium, and americium) indicates a monotonic increase in the excitation energy. The sharp edgelike structure of the multielectron excitation reveals the origin of a shake-up channel.

  13. The Ozone Show.

    ERIC Educational Resources Information Center

    Mathieu, Aaron

    2000-01-01

    Uses a talk show activity for a final assessment tool for students to debate about the ozone hole. Students are assessed on five areas: (1) cooperative learning; (2) the written component; (3) content; (4) self-evaluation; and (5) peer evaluation. (SAH)

  14. Show What You Know

    ERIC Educational Resources Information Center

    Eccleston, Jeff

    2007-01-01

    Big things come in small packages. This saying came to the mind of the author after he created a simple math review activity for his fourth grade students. Though simple, it has proven to be extremely advantageous in reinforcing math concepts. He uses this activity, which he calls "Show What You Know," often. This activity provides the perfect…

  15. Showing What They Know

    ERIC Educational Resources Information Center

    Cech, Scott J.

    2008-01-01

    Having students show their skills in three dimensions, known as performance-based assessment, dates back at least to Socrates. Individual schools such as Barrington High School--located just outside of Providence--have been requiring students to actively demonstrate their knowledge for years. The Rhode Island's high school graduating class became…

  16. Stage a Water Show

    ERIC Educational Resources Information Center

    Frasier, Debra

    2008-01-01

    In the author's book titled "The Incredible Water Show," the characters from "Miss Alaineus: A Vocabulary Disaster" used an ocean of information to stage an inventive performance about the water cycle. In this article, the author relates how she turned the story into hands-on science teaching for real-life fifth-grade students. The author also…

  17. What Do Maps Show?

    ERIC Educational Resources Information Center

    Geological Survey (Dept. of Interior), Reston, VA.

    This curriculum packet, appropriate for grades 4-8, features a teaching poster which shows different types of maps (different views of Salt Lake City, Utah), as well as three reproducible maps and reproducible activity sheets which complement the maps. The poster provides teacher background, including step-by-step lesson plans for four geography…

  18. Obesity in show cats.

    PubMed

    Corbee, R J

    2014-12-01

    Obesity is an important disease with a high prevalence in cats. Because obesity is related to several other diseases, it is important to identify the population at risk. Several risk factors for obesity have been described in the literature. A higher incidence of obesity in certain cat breeds has been suggested. The aim of this study was to determine whether obesity occurs more often in certain breeds. The second aim was to relate the increased prevalence of obesity in certain breeds to the official standards of that breed. To this end, 268 cats of 22 different breeds investigated by determining their body condition score (BCS) on a nine-point scale by inspection and palpation, at two different cat shows. Overall, 45.5% of the show cats had a BCS > 5, and 4.5% of the show cats had a BCS > 7. There were significant differences between breeds, which could be related to the breed standards. Most overweight and obese cats were in the neutered group. It warrants firm discussions with breeders and cat show judges to come to different interpretations of the standards in order to prevent overweight conditions in certain breeds from being the standard of beauty. Neutering predisposes for obesity and requires early nutritional intervention to prevent obese conditions. PMID:24612018

  19. Show Me the Way

    ERIC Educational Resources Information Center

    Dicks, Matthew J.

    2005-01-01

    Because today's students have grown up steeped in video games and the Internet, most of them expect feedback, and usually gratification, very soon after they expend effort on a task. Teachers can get quick feedback to students by showing them videotapes of their learning performances. The author, a 3rd grade teacher describes how the seemingly…

  20. The Art Show

    ERIC Educational Resources Information Center

    Scolarici, Alicia

    2004-01-01

    This article describes what once was thought to be impossible--a formal art show extravaganza at an elementary school with 1,000 students, a Department of Defense Dependent School (DODDS) located overseas, on RAF Lakenheath, England. The dream of this this event involved the transformation of the school cafeteria into an elegant art show…

  1. Honored Teacher Shows Commitment.

    ERIC Educational Resources Information Center

    Ratte, Kathy

    1987-01-01

    Part of the acceptance speech of the 1985 National Council for the Social Studies Teacher of the Year, this article describes the censorship experience of this honored social studies teacher. The incident involved the showing of a videotape version of the feature film entitled "The Seduction of Joe Tynan." (JDH)

  2. Electronic absorption spectrum of triacetylene cation for astronomical considerations.

    PubMed

    Chakrabarty, S; Rice, C A; Mazzotti, F J; Dietsche, R; Maier, J P

    2013-10-01

    The A(2)Πg ← X(2)Πu electronic transition (4800-6000 Å) of triacetylene cation was measured in an ion trap, where the vibrational and rotational degrees of freedom were equilibrated to 25 K. The rotational profile of the origin band is predicted by a collisional-radiative rate model under conditions expected in diffuse interstellar clouds. Variation in the density of the surrounding gas, rotational temperature, and velocity dispersion are taken into account.

  3. The geoid spectrum from altimetry

    NASA Technical Reports Server (NTRS)

    Wagner, C. A.

    1978-01-01

    Satellite altimetry information from the world's major oceans was analyzed to arrive at a geoid power spectrum. Using the equivalent of about 7 revolutions of data (mostly from GEOS-3) the power spectrum of the sea surface generally follows the expected values from Kaula's rule applied to the geoid. Analysis of overlapping altimetry arcs (and oceanographic data) shows that the surface spectrum is dominated by the geoid to about 500 cycles (40 km half wavelength) but that sea state departures are significant starting at about 250 cycles (80 km). Estimates of geopotential variances from a derived (smooth) geoid spectrum show significantly less power than Kaula's rule to about 60 cycles, but somewhat more from there to about 400 cycles. At less than 40 km half wavelength, the total power in the marine geoid may be negligible.

  4. Holographic spectrum-splitting optical systems for solar photovoltaics

    NASA Astrophysics Data System (ADS)

    Zhang, Deming

    Solar energy is the most abundant source of renewable energy available. The relatively high cost prevents solar photovoltaic (PV) from replacing fossil fuel on a larger scale. In solar PV power generation the cost is reduced with more efficient PV technologies. In this dissertation, methods to improve PV conversion efficiency with holographic optical components are discussed. The tandem multiple-junction approach has achieved very high conversion efficiency. However it is impossible to manufacture tandem PV cells at a low cost due to stringent fabrication standards and limited material types that satisfy lattice compatibility. Current produced by the tandem multi-junction PV cell is limited by the lowest junction due to series connection. Spectrum-splitting is a lateral multi-junction concept that is free of lattice and current matching constraints. Each PV cell can be optimized towards full absorption of a spectral band with tailored light-trapping schemes. Holographic optical components are designed to achieve spectrum-splitting PV energy conversion. The incident solar spectrum is separated onto multiple PV cells that are matched to the corresponding spectral band. Holographic spectrum-splitting can take advantage of existing and future low-cost technologies that produces high efficiency thin-film solar cells. Spectrum-splitting optical systems are designed and analyzed with both transmission and reflection holographic optical components. Prototype holograms are fabricated and high optical efficiency is achieved. Light-trapping in PV cells increases the effective optical path-length in the semiconductor material leading to improved absorption and conversion efficiency. It has been shown that the effective optical path length can be increased by a factor of 4n2 using diffusive surfaces. Ultra-light-trapping can be achieved with optical filters that limit the escape angle of the diffused light. Holographic reflection gratings have been shown to act as angle

  5. Triplet absorption spectroscopy and electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Ghafoor, F.; Nazmitdinov, R. G.

    2016-09-01

    Coherence phenomena in a four-level atomic system, cyclically driven by three coherent fields, are investigated thoroughly at zero and weak magnetic fields. Each strongly interacting atomic state is converted to a triplet due to a dynamical Stark effect. Two dark lines with a Fano-like profile arise in the triplet absorption spectrum with anomalous dispersions. We provide conditions to control the widths of the transparency windows by means of the relative phase of the driving fields and the intensity of the microwave field, which closes the optical system loop. The effect of Doppler broadening on the results of the triplet absorption spectroscopy is analysed in detail.

  6. Lyapunov spectrum of granular gases

    SciTech Connect

    McNamara, Sean; Mareschal, Michel

    2001-06-01

    We calculate and study the Lyapunov spectrum of a granular gas maintained in a steady state by an isokinetic thermostat. Considering restitution coefficients greater than unity allows us to show that the spectra change smoothly and continuously at equilibrium. The shearing instability of the granular gas, however, provokes an abrupt change in the structure of the spectrum. The relationship between various physically relevant quantities and the energy dissipation rate differs from previously studied nonequilibrium steady states.

  7. Taking in a Show.

    PubMed

    Boden, Timothy W

    2016-01-01

    Many medical practices have cut back on education and staff development expenses, especially those costs associated with conventions and conferences. But there are hard-to-value returns on your investment in these live events--beyond the obvious benefits of acquired knowledge and skills. Major vendors still exhibit their services and wares at many events, and the exhibit hall is a treasure-house of information and resources for the savvy physician or administrator. Make and stick to a purposeful plan to exploit the trade show. You can compare products, gain new insights and ideas, and even negotiate better deals with representatives anxious to realize returns on their exhibition investments. PMID:27249887

  8. Taking in a Show.

    PubMed

    Boden, Timothy W

    2016-01-01

    Many medical practices have cut back on education and staff development expenses, especially those costs associated with conventions and conferences. But there are hard-to-value returns on your investment in these live events--beyond the obvious benefits of acquired knowledge and skills. Major vendors still exhibit their services and wares at many events, and the exhibit hall is a treasure-house of information and resources for the savvy physician or administrator. Make and stick to a purposeful plan to exploit the trade show. You can compare products, gain new insights and ideas, and even negotiate better deals with representatives anxious to realize returns on their exhibition investments.

  9. Obesity in show dogs.

    PubMed

    Corbee, R J

    2013-10-01

    Obesity is an important disease with a growing incidence. Because obesity is related to several other diseases, and decreases life span, it is important to identify the population at risk. Several risk factors for obesity have been described in the literature. A higher incidence of obesity in certain breeds is often suggested. The aim of this study was to determine whether obesity occurs more often in certain breeds. The second aim was to relate the increased prevalence of obesity in certain breeds to the official standards of that breed. To this end, we investigated 1379 dogs of 128 different breeds by determining their body condition score (BCS). Overall, 18.6% of the show dogs had a BCS >5, and 1.1% of the show dogs had a BCS>7. There were significant differences between breeds, which could be correlated to the breed standards. It warrants firm discussions with breeders and judges in order to come to different interpretations of the standards to prevent overweight conditions from being the standard of beauty. PMID:22882163

  10. Cathodoluminescence Spectrum Imaging Software

    2011-04-07

    The software developed for spectrum imaging is applied to the analysis of the spectrum series generated by our cathodoluminescence instrumentation. This software provides advanced processing capabilities s such: reconstruction of photon intensity (resolved in energy) and photon energy maps, extraction of the spectrum from selected areas, quantitative imaging mode, pixel-to-pixel correlation spectrum line scans, ASCII, output, filling routines, drift correction, etc.

  11. Application of methane band-model parameters to the visible and near-infrared spectrum of Uranus

    NASA Technical Reports Server (NTRS)

    Benner, D. C.; Fink, U.

    1980-01-01

    Laboratory band-model absorption coefficients of CH4 were used to calculate the Uranus spectrum from 5400 to 10,400 A. A good fit for both strong and weak bands for the Uranus spectrum over the entire wavelength interval was achieved; three atmospheric models were employed: (1) a reflecting layer model; (2) a homogeneous scattering layer model; and (3) a clear atmosphere sandwiched between two scattering layers. The spectrum for the reflecting layer model shows serious discrepancies but indicates that large amounts of CH4 are necessary to reproduce the Uranus spectrum. Both scattering models gave reasonably good fits; the homogeneous model requires a particle scattering albedo of at least 0.998 and an abundance per scattering mean free path of about 1 km-am. For the sandwich model, a continuum single scattering albedo of 0.995 was derived for the upper scattering layer, and the scattering optical depth variable wavelength was consistent with Rayleigh scattering.

  12. The marine diversity spectrum.

    PubMed

    Reuman, Daniel C; Gislason, Henrik; Barnes, Carolyn; Mélin, Frédéric; Jennings, Simon

    2014-07-01

    Distributions of species body sizes within a taxonomic group, for example, mammals, are widely studied and important because they help illuminate the evolutionary processes that produced these distributions. Distributions of the sizes of species within an assemblage delineated by geography instead of taxonomy (all the species in a region regardless of clade) are much less studied but are equally important and will illuminate a different set of ecological and evolutionary processes. We develop and test a mechanistic model of how diversity varies with body mass in marine ecosystems. The model predicts the form of the 'diversity spectrum', which quantifies the distribution of species' asymptotic body masses, is a species analogue of the classic size spectrum of individuals, and which we have found to be a new and widely applicable description of diversity patterns. The marine diversity spectrum is predicted to be approximately linear across an asymptotic mass range spanning seven orders of magnitude. Slope -0.5 is predicted for the global marine diversity spectrum for all combined pelagic zones of continental shelf seas, and slopes for large regions are predicted to lie between -0.5 and -0.1. Slopes of -0.5 and -0.1 represent markedly different communities: a slope of -0.5 depicts a 10-fold reduction in diversity for every 100-fold increase in asymptotic mass; a slope of -0.1 depicts a 1.6-fold reduction. Steeper slopes are predicted for larger or colder regions, meaning fewer large species per small species for such regions. Predictions were largely validated by a global empirical analysis. Results explain for the first time a new and widespread phenomenon of biodiversity. Results have implications for estimating numbers of species of small asymptotic mass, where taxonomic inventories are far from complete. Results show that the relationship between diversity and body mass can be explained from the dependence of predation behaviour, dispersal, and life history on

  13. The marine diversity spectrum.

    PubMed

    Reuman, Daniel C; Gislason, Henrik; Barnes, Carolyn; Mélin, Frédéric; Jennings, Simon

    2014-07-01

    Distributions of species body sizes within a taxonomic group, for example, mammals, are widely studied and important because they help illuminate the evolutionary processes that produced these distributions. Distributions of the sizes of species within an assemblage delineated by geography instead of taxonomy (all the species in a region regardless of clade) are much less studied but are equally important and will illuminate a different set of ecological and evolutionary processes. We develop and test a mechanistic model of how diversity varies with body mass in marine ecosystems. The model predicts the form of the 'diversity spectrum', which quantifies the distribution of species' asymptotic body masses, is a species analogue of the classic size spectrum of individuals, and which we have found to be a new and widely applicable description of diversity patterns. The marine diversity spectrum is predicted to be approximately linear across an asymptotic mass range spanning seven orders of magnitude. Slope -0.5 is predicted for the global marine diversity spectrum for all combined pelagic zones of continental shelf seas, and slopes for large regions are predicted to lie between -0.5 and -0.1. Slopes of -0.5 and -0.1 represent markedly different communities: a slope of -0.5 depicts a 10-fold reduction in diversity for every 100-fold increase in asymptotic mass; a slope of -0.1 depicts a 1.6-fold reduction. Steeper slopes are predicted for larger or colder regions, meaning fewer large species per small species for such regions. Predictions were largely validated by a global empirical analysis. Results explain for the first time a new and widespread phenomenon of biodiversity. Results have implications for estimating numbers of species of small asymptotic mass, where taxonomic inventories are far from complete. Results show that the relationship between diversity and body mass can be explained from the dependence of predation behaviour, dispersal, and life history on

  14. 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

  15. Not a "reality" show.

    PubMed

    Wrong, Terence; Baumgart, Erica

    2013-01-01

    The authors of the preceding articles raise legitimate questions about patient and staff rights and the unintended consequences of allowing ABC News to film inside teaching hospitals. We explain why we regard their fears as baseless and not supported by what we heard from individuals portrayed in the filming, our decade-long experience making medical documentaries, and the full un-aired context of the scenes shown in the broadcast. The authors don't and can't know what conversations we had, what documents we reviewed, and what protections we put in place in each televised scene. Finally, we hope to correct several misleading examples cited by the authors as well as their offhand mischaracterization of our program as a "reality" show. PMID:23631336

  16. Not a "reality" show.

    PubMed

    Wrong, Terence; Baumgart, Erica

    2013-01-01

    The authors of the preceding articles raise legitimate questions about patient and staff rights and the unintended consequences of allowing ABC News to film inside teaching hospitals. We explain why we regard their fears as baseless and not supported by what we heard from individuals portrayed in the filming, our decade-long experience making medical documentaries, and the full un-aired context of the scenes shown in the broadcast. The authors don't and can't know what conversations we had, what documents we reviewed, and what protections we put in place in each televised scene. Finally, we hope to correct several misleading examples cited by the authors as well as their offhand mischaracterization of our program as a "reality" show.

  17. Fraunhofer effect atomic absorption spectrometry.

    PubMed

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

    2005-02-15

    The dark lines in the solar spectrum were discovered by Wollaston and cataloged by Fraunhofer in the early days of the 19th century. Some years later, Kirchhoff explained the appearance of the dark lines: the sun was acting as a continuum light source and metals in the ground state in its atmosphere were absorbing characteristic narrow regions of the spectrum. This discovery eventually spawned atomic absorption spectrometry, which became a routine technique for chemical analysis in the mid-20th century. Laboratory-based atomic absorption spectrometers differ from the original observation of the Fraunhofer lines because they have always employed a separate light source and atomizer. This article describes a novel atomic absorption device that employs a single source, the tungsten coil, as both the generator of continuum radiation and the atomizer of the analytes. A 25-microL aliquot of sample is placed on the tungsten filament removed from a commercially available 150-W light bulb. The solution is dried and ashed by applying low currents to the coil in a three-step procedure. Full power is then applied to the coil for a brief period. During this time, the coil produces white light, which may be absorbed by any metals present in the atomization cloud produced by the sample. A high-resolution spectrometer with a charge-coupled device detector monitors the emission spectrum of the coil, which includes the dark lines from the metals. Detection limits are reported for seven elements: 5 pg of Ca (422.7 nm); 2 ng of Co (352.7 nm); 200 pg of Cr (425.4 nm); 7 pg of Sr (460.7 nm); 100 pg of Yb (398.8 nm); 500 pg of Mn (403.1 nm); and 500 pg of K (404.4 nm). Simultaneous multielement analyses are possible within a 4-nm spectral window. The relative standard deviations for the seven metals are below 8% for all metals except for Ca (10.7%), which was present in the blank at measurable levels. Analysis of a standard reference material (drinking water) resulted in a mean percent

  18. Self-aggregation and optical absorption of stilbazolium merocyanine in chloroform.

    PubMed

    Silva, Daniel L; Murugan, N Arul; Kongsted, Jacob; Ågren, Hans; Canuto, Sylvio

    2014-02-20

    Dipolar aggregation is in many cases detrimental for the functioning of optical materials. In this study we investigate self-aggregation and optical absorption of stilbazolium merocyanine (SM) in chloroform solution by performing classical Molecular Dynamics (MD) simulations under ambient conditions. The reversal solvatochromic shift, the large bathochromic shift, and the structured absorption band presented by SM in chloroform solution are all aspects of its optical absorption behavior for which the existence of self-aggregation is yet not completely understood. Moreover, the spectroscopic properties of SM oligomers and their occurrence in solvent of low polarity remain a relevant topic that deserves to be investigated. Our analysis of the aggregation behavior of SM in chloroform verified that the majority of the chromophores are involved in the formation of oligomers in solution, where the whole dimer and part of the trimer populations present a stable π-stacking structure. The optical properties of the monomers and oligomers in solution were evaluated by means of a discrete polarizable embedding quantum mechanical/molecular mechanical (PE-QM/MM) response scheme where the quantum part is described at the level of density functional theory. The visible absorption spectrum of SM in chloroform is simulated using time average values obtained for the monomeric and oligomeric forms of SM from the PE-QM/MM calculations performed on uncorrelated configurations extracted from the classical MD simulations. This study shows that the self-aggregation of SM in chloroform may exist, but it is not essential for reproducing the reversal solvatochromic shift in chloroform and that the process does not contribute to enhance the bathochromic shift nor explain the structure observed in its absorption band. Moreover, it is verified that since the electronic transitions of the monomer and oligomers are close together, changes in the interplane separation between the monomeric units

  19. The infrared spectrum of Rhea

    NASA Technical Reports Server (NTRS)

    Clark, R. N.; Owensby, P. D.

    1981-01-01

    The reflectance spectrum of the leading side of the Saturnian satellite Rhea in the 0.65 to 2.5 micron range is reported and used to quantify the amount of water and other materials present on the surface. Data were obtained with 1.5% spectral resolution and 3 to 5% precision by the 3.0-m Infrared Telescope Facility at Mauna Kea Observatory with a continuously scanning circular variable filter spectrometer. Water ice absorptions previously identified at 2.02, 1.65 and 1.55 microns are confirmed, and additional absorptions at 1.25 and probably 1.04 microns are identified. The spectrum of Rhea is noted to be very similar to that of the leading side of Ganymede in the 0.6 to 2.5 micron region and to laboratory spectra of water frost on ice blocks rather than an optically thick frost. Results indicate that the leading side of Rhea is at least 90 wt % water ice, and may be as much as 98 wt %. Of the remaining material, neither clathrates nor minerals is excluded.

  20. Public medical shows.

    PubMed

    Walusinski, Olivier

    2014-01-01

    In the second half of the 19th century, Jean-Martin Charcot (1825-1893) became famous for the quality of his teaching and his innovative neurological discoveries, bringing many French and foreign students to Paris. A hunger for recognition, together with progressive and anticlerical ideals, led Charcot to invite writers, journalists, and politicians to his lessons, during which he presented the results of his work on hysteria. These events became public performances, for which physicians and patients were transformed into actors. Major newspapers ran accounts of these consultations, more like theatrical shows in some respects. The resultant enthusiasm prompted other physicians in Paris and throughout France to try and imitate them. We will compare the form and substance of Charcot's lessons with those given by Jules-Bernard Luys (1828-1897), Victor Dumontpallier (1826-1899), Ambroise-Auguste Liébault (1823-1904), Hippolyte Bernheim (1840-1919), Joseph Grasset (1849-1918), and Albert Pitres (1848-1928). We will also note their impact on contemporary cinema and theatre. PMID:25273491

  1. Infrared absorption and emission characteristics of interstellar PAHs

    NASA Technical Reports Server (NTRS)

    Barker, J. R.; Allamandola, Louis J.; Tielens, Alexander G. G. M.; Barker, J. R.; Barker, J. R.

    1986-01-01

    The mid-infrared interstellar emission spectrum with features at 3.28, 6.2, 7.7, 8.7 and 11.3 microns is discussed in terms of the Polycyclic Aromatic Hydrocarbon (PAH) hypothesis, which is based on the suggestive, but inconclusive comparison between the interstellar emission spectrum with the infrared absorption and Raman spectra of a few PAHs. The fundamental vibrations of PAHs and PAH-like species which determine the IR and Raman properties are discussed. Interstellar IR band emission is due to relaxation from highly vibrationally excited PAHs excited by ultraviolet photons. The excitation/emission process is described and the IR fluorescence from one PAH, chrysene, is traced. Generally, there is sufficient energy to populate several vibrational levels in each mode. Molecular vibrational potentials are anharmonic and emission from these higher levels will fall at lower frequencies and produce weak features to the red of the stronger fundamentals. This process is also described and can account for some spectroscopic details of the interstellar emission spectra previously unexplained. Analysis of the interstellar spectrum shows that PAHs contain between 20 and 30 carbon atoms are responsible for the emission.

  2. Discovery of Extremely Broad Balmer Absorption Lines in SDSS J152350.42+391405.2

    NASA Astrophysics Data System (ADS)

    Zhang, Shaohua; Zhou, Hongyan; Shi, Xiheng; Shu, Xinwen; Liu, Wenjuan; Ji, Tuo; Jiang, Peng; Sun, Luming; Zhou, Junyan; Pan, Xiang

    2015-12-01

    We present the discovery of Balmer line absorption from Hα to Hγ in an iron low-ionization broad absorption line (FeLoBAL) quasar SDSS J152350.42+391405.2 (hereafter SDSS J1523+3914), by the quasi-simultaneous optical and near-infrared spectroscopy. The Balmer line absorption is at {z}{absor}=0.6039+/- 0.0021 and blueshifted by v = 10,353 km s-1 with respect to the Balmer emission lines. All Balmer BALs have a uniform absorption profile with the widths of {{Δ }}v˜ 12,000 km s-1. We also found the absorption trough in He i* λ10830 with the same velocity and width in the H-band TripleSpec spectrum of SDSS J1523+3914. This object is only the 10th active galactic nucleus known to exhibit nonstellar Balmer absorption, as well as the case with the highest velocity and broadest Balmer absorption lines that have ever been found. A CLOUDY analysis shows that the absorbers require a gas density of {{log}}10 {n}{{e}} ({{cm}}-3)=9 and an ionization parameter of {{log}}10 U=-1.0. They are located at a distance of ˜0.2 pc from the central ionizing source, which is slightly farther than that of broad emission line regions. Furthermore, SDSS J1523+3914 is one of the brightest Balmer BAL quasars ever reported, with unique iron absorption variations, making it the most promising candidate for follow-up high-resolution spectroscopy, multiband observations, and long-term monitoring.

  3. The Great Cometary Show

    NASA Astrophysics Data System (ADS)

    2007-01-01

    its high spatial and spectral resolution, it was possible to zoom into the very heart of this very massive star. In this innermost region, the observations are dominated by the extremely dense stellar wind that totally obscures the underlying central star. The AMBER observations show that this dense stellar wind is not spherically symmetric, but exhibits a clearly elongated structure. Overall, the AMBER observations confirm that the extremely high mass loss of Eta Carinae's massive central star is non-spherical and much stronger along the poles than in the equatorial plane. This is in agreement with theoretical models that predict such an enhanced polar mass-loss in the case of rapidly rotating stars. ESO PR Photo 06c/07 ESO PR Photo 06c/07 RS Ophiuchi in Outburst Several papers from this special feature focus on the later stages in a star's life. One looks at the binary system Gamma 2 Velorum, which contains the closest example of a star known as a Wolf-Rayet. A single AMBER observation allowed the astronomers to separate the spectra of the two components, offering new insights in the modeling of Wolf-Rayet stars, but made it also possible to measure the separation between the two stars. This led to a new determination of the distance of the system, showing that previous estimates were incorrect. The observations also revealed information on the region where the winds from the two stars collide. The famous binary system RS Ophiuchi, an example of a recurrent nova, was observed just 5 days after it was discovered to be in outburst on 12 February 2006, an event that has been expected for 21 years. AMBER was able to detect the extension of the expanding nova emission. These observations show a complex geometry and kinematics, far from the simple interpretation of a spherical fireball in extension. AMBER has detected a high velocity jet probably perpendicular to the orbital plane of the binary system, and allowed a precise and careful study of the wind and the shockwave

  4. Stretched View Showing 'Victoria'

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Stretched View Showing 'Victoria'

    This pair of images from the panoramic camera on NASA's Mars Exploration Rover Opportunity served as initial confirmation that the two-year-old rover is within sight of 'Victoria Crater,' which it has been approaching for more than a year. Engineers on the rover team were unsure whether Opportunity would make it as far as Victoria, but scientists hoped for the chance to study such a large crater with their roving geologist. Victoria Crater is 800 meters (nearly half a mile) in diameter, about six times wider than 'Endurance Crater,' where Opportunity spent several months in 2004 examining rock layers affected by ancient water.

    When scientists using orbital data calculated that they should be able to detect Victoria's rim in rover images, they scrutinized frames taken in the direction of the crater by the panoramic camera. To positively characterize the subtle horizon profile of the crater and some of the features leading up to it, researchers created a vertically-stretched image (top) from a mosaic of regular frames from the panoramic camera (bottom), taken on Opportunity's 804th Martian day (April 29, 2006).

    The stretched image makes mild nearby dunes look like more threatening peaks, but that is only a result of the exaggerated vertical dimension. This vertical stretch technique was first applied to Viking Lander 2 panoramas by Philip Stooke, of the University of Western Ontario, Canada, to help locate the lander with respect to orbiter images. Vertically stretching the image allows features to be more readily identified by the Mars Exploration Rover science team.

    The bright white dot near the horizon to the right of center (barely visible without labeling or zoom-in) is thought to be a light-toned outcrop on the far wall of the crater, suggesting that the rover can see over the low rim of Victoria. In figure 1, the northeast and southeast rims are labeled

  5. Representation and transformation of Langley's map of the infrared solar spectrum

    NASA Astrophysics Data System (ADS)

    Loettgers, Andrea

    In 1900, after 18 years of research, the American astrophysicist Samuel Pierpont Langley published the final report of his investigations in the infrared region of the solar spectrum. (See Samuel P. Langley: Annals of the Astrophysical Observatory of the Smithsonian Institution, Vol. 1, Washington: Goverment Printing Office, 1900.) In this report one finds three different types of maps of the infrared region, extending from 1.1 mu-m to 5.3 mu-m and showing the positions of 750 absorption lines: a bolograph, a line spectrum and a normal spectrum. (The bolograph, the line spectrum and the normal spectrum are accessible as pl. XX and XXIV at http://adsbit.harvard.edu/books/saoann/.) Looking at these three distinct forms of representation raises the questions: Why did Langley decide to use three representations for the visualization of his results? How are these distinct representations connected? An analysis of the first question will provide further insight into the ``connection between instruments, practices, and the visual'', into the recording, evaluation and processing of the data and, furthermore, into the historical and disciplinary contexts. The prevailing trend toward the automation of measuring and registration processes, and the associated claim of `mechanical objectivity', together with standards concerning precision and completeness set by Henry Rowland's photographic measurements in the visible part of the spectrum, turn out to be the strongest elements in the development of the different forms of representation and their respective transformations.

  6. Evidence for active galactic nucleus feedback in the broad absorption lines and reddening of MRK 231 {sup ,}

    SciTech Connect

    Leighly, Karen M.; Baron, Eddie; Lucy, Adrian B.; Terndrup, Donald M.; Dietrich, Matthias; Gallagher, Sarah C.

    2014-06-20

    We present the first J-band spectrum of Mrk 231, which reveals a large He I* λ10830 broad absorption line with a profile similar to that of the well-known Na I broad absorption line. Combining this spectrum with optical and UV spectra from the literature, we show that the unusual reddening noted by Veilleux et al. is explained by a reddening curve like those previously used to explain low values of total-to-selective extinction in Type Ia supernovae. The nuclear starburst may be the origin and location of the dust. Spatially resolved emission in the broad absorption line trough suggests nearly full coverage of the continuum emission region. The broad absorption lines reveal higher velocities in the He I* lines (produced in the quasar-photoionized H II region) compared with the Na I and Ca II lines (produced in the corresponding partially ionized zone). Cloudy simulations show that a density increase is required between the H II and partially ionized zones to produce ionic column densities consistent with the optical and IR absorption line measurements and limits, and that the absorber lies ∼100 pc from the central engine. These results suggest that the He I* lines are produced in an ordinary quasar BAL wind that impacts upon, compresses, and accelerates the nuclear starburst's dusty effluent (feedback in action), and the Ca II and Na I lines are produced in this dusty accelerated gas. This unusual circumstance explains the rarity of Na I absorption lines; without the compression along our line of sight, Mrk 231 would appear as an ordinary iron low-ionization, broad absorption line quasar.

  7. Gamma-ray Background Spectrum and Annihilation Rate in the Baryon-symmetric Big-bang Cosmology

    NASA Technical Reports Server (NTRS)

    Puget, J. L.

    1973-01-01

    An attempt was made to acquire experimental information on the problem of baryon symmetry on a large cosmological scale by observing the annihilation products. Data cover absorption cross sections and background radiation due to other sources for the two main products of annihilation, gamma rays and neutrinos. Test results show that the best direct experimental test for the presence of large scale antimatter lies in the gamma ray background spectrum between 1 and 70 MeV.

  8. The 1.7- to 4.2-micron spectrum of asteroid 1 Ceres - Evidence for structural water in clay minerals

    NASA Technical Reports Server (NTRS)

    Lebofsky, L. A.; Feierberg, M. A.; Larson, H. P.; Johnson, J. R.; Tokunaga, A. T.

    1981-01-01

    A high-resolution Fourier spectrum (1.7-3.5 microns) and medium-resolution spectrophotometry (2.7-4.2 microns) were obtained for Asteroid 1 Ceres. The presence of the 3-micron absorption feature due to water of hydration was confirmed. The 3-micron feature is compared with the 3-micron bands due to water of hydration in clays and salts. It is concluded that the spectrum of Ceres shows a strong absorption at 2.7-2.8 microns due to structural OH groups in clay minerals. The dominant minerals on the surface of Ceres are therefore hydrated clay minerals structurally similar to terrestrial montmorillonites. There is also a narrow absorption feature at 3.1 microns which is attributable to a very small amount of water ice on Ceres. This is the first evidence for ice on the surface of an asteroid.

  9. Enhanced compressive wideband frequency spectrum sensing for dynamic spectrum access

    NASA Astrophysics Data System (ADS)

    Liu, Yipeng; Wan, Qun

    2012-12-01

    Wideband spectrum sensing detects the unused spectrum holes for dynamic spectrum access (DSA). Too high sampling rate is the main challenge. Compressive sensing (CS) can reconstruct sparse signal with much fewer randomized samples than Nyquist sampling with high probability. Since survey shows that the monitored signal is sparse in frequency domain, CS can deal with the sampling burden. Random samples can be obtained by the analog-to-information converter. Signal recovery can be formulated as the combination of an L0 norm minimization and a linear measurement fitting constraint. In DSA, the static spectrum allocation of primary radios means the bounds between different types of primary radios are known in advance. To incorporate this a priori information, we divide the whole spectrum into sections according to the spectrum allocation policy. In the new optimization model, the minimization of the L2 norm of each section is used to encourage the cluster distribution locally, while the L0 norm of the L2 norms is minimized to give sparse distribution globally. Because the L2/L0 optimization is not convex, an iteratively re-weighted L2/L1 optimization is proposed to approximate it. Simulations demonstrate the proposed method outperforms others in accuracy, denoising ability, etc.

  10. Presence of terrestrial atmospheric gas absorption bands in standard extraterrestrial solar irradiance curves in the near-infrared spectral region.

    PubMed

    Gao, B C; Green, R O

    1995-09-20

    The solar irradiance curves compiled by Wehrli [Physikalisch-Meteorologisches Observatorium Publ. 615 (World Radiation Center, Davosdorf, Switzerland, 1985)] and by Neckel and Labs [Sol. Phys. 90, 205 (1984)] are widely used. These curves were obtained based on measurements of solar radiation from the ground and from aircraft platforms. Contaminations in these curves by atmospheric gaseous absorptions were inevitable. A technique for deriving the transmittance spectrum of the Sun's atmosphere from high-resolution (0.01 cm(-1)) solar occultation spectra measured above the Earth's atmosphere by the use of atmospheric trace molecule spectroscopy (ATMOS) aboard the space shuttle is described. The comparisons of the derived ATMOS solar transmittance spectrum with the two solar irradiance curves show that he curve derived by Wehrli contains many absorption features in the 2.0-2.5-µm region that are not of solar origin, whereas the curve obtained by Neckel and Labs is completely devoid of weak solar absorption features that should be there. An Earth atmospheric oxygen band at 1.268 µm and a water-vapor band near 0.94 µm are likely present in the curve obtained by Wehrli. It is shown that the solar irradiance measurement errors in some narrow spectral intervals can be as large as 20%. An improved solar irradiance spectrum is formed by the incorporation of the solar transmittance spectrum derived from the ATMOS data into the solar irradiance spectrum from Neckel and Labs. The availability of a new solar spectrum from 50 to 50 000 cm(-1) from the U.S. Air Force Phillips Laboratory is also discussed.

  11. A spectrum of an extrasolar planet.

    PubMed

    Richardson, L Jeremy; Deming, Drake; Horning, Karen; Seager, Sara; Harrington, Joseph

    2007-02-22

    Of the over 200 known extrasolar planets, 14 exhibit transits in front of their parent stars as seen from Earth. Spectroscopic observations of the transiting planets can probe the physical conditions of their atmospheres. One such technique can be used to derive the planetary spectrum by subtracting the stellar spectrum measured during eclipse (planet hidden behind star) from the combined-light spectrum measured outside eclipse (star + planet). Although several attempts have been made from Earth-based observatories, no spectrum has yet been measured for any of the established extrasolar planets. Here we report a measurement of the infrared spectrum (7.5-13.2 microm) of the transiting extrasolar planet HD 209458b. Our observations reveal a hot thermal continuum for the planetary spectrum, with an approximately constant ratio to the stellar flux over this wavelength range. Superposed on this continuum is a broad emission peak centred near 9.65 microm that we attribute to emission by silicate clouds. We also find a narrow, unidentified emission feature at 7.78 microm. Models of these 'hot Jupiter' planets predict a flux peak near 10 microm, where thermal emission from the deep atmosphere emerges relatively unimpeded by water absorption, but models dominated by water fit the observed spectrum poorly.

  12. Absorption and emission in quantum dots: Fermi surface effects of Anderson excitons

    NASA Astrophysics Data System (ADS)

    Helmes, R. W.; Sindel, M.; Borda, L.; von Delft, J.

    2005-09-01

    Recent experiments measuring the emission of exciton recombination in a self-organized single quantum dot (QD) have revealed that different effects occur when the wetting layer surrounding the QD becomes filled with electrons because the resulting Fermi sea can hybridize with the local electron levels on the dot. Motivated by these experiments, we study an extended Anderson model, which describes a local conduction band level coupled to a Fermi sea, but also includes a local valence band level. We are interested, in particular, in how many-body correlations resulting from the presence of the Fermi sea affect the absorption and emission spectra. Using Wilson’s numerical renormalization group method, we calculate the zero-temperature absorption (emission) spectrum of a QD, which starts from (ends up in) a strongly correlated Kondo ground state. We predict two features: First, we find that the spectrum shows a power-law divergence close to the threshold, with an exponent that can be understood by analogy to the well-known x-ray edge absorption problem. Second, the threshold energy ω0 —below which no photon is absorbed (above which no photon is emitted)—shows a marked, monotonic shift as a function of the exciton binding energy Uexc .

  13. Improvement of differential optical absorption spectroscopy with a multichannel scanning technique.

    PubMed

    Brauers, T; Hausmann, M; Brandenburger, U; Dorn, H P

    1995-07-20

    Differential optical absorption spectroscopy (DOAS) of atmospheric trace gases requires the detection of optical densities below 0.1%. Photodiode arrays are used more and more as detectors for DOAS because they allow one to record larger spectral intervals simultaneously. This type of optical multichannel analyzer (OMA), however, shows sensitivity differences among the individual photodiodes (pixels), which are of the order of 1%. To correct for this a sensitivity reference spectrum is usually recorded separately from the trace-gas measurements. Because of atmospheric turbulence the illumination of the detector while an atmospheric absorption spectrum is being recorded is different from the conditions during the reference measurement. As a result the sensitivity patterns do not exactly match, and the corrected spectra still show a residual structure that is due to the sensitivity difference. This effect usually limits the detection of optical densities to approximately 3 × 10(-4). A new method for the removal of the sensitivity pattern is presented in this paper: Scanning the spectrometer by small wavelength increments after each readout of the OMA allows one to separate the OMA-fixed pattern and the wavelength-fixed structures (absorption lines). The properties of the new method and its applicability are demonstrated with simulated spectra. Finally, first atmospheric measurements with a laser long-path instrument demonstrate a detection limit of 3 × 10(-5) of a DOAS experiment. PMID:21052280

  14. Absorption spectra of crystalline limestones experimentally deformed or tectonised

    NASA Astrophysics Data System (ADS)

    Cervelle, B.; ChayéD'Albissin, M.; Gouet, G.; Visocekas, R.

    1982-11-01

    Diffuse-reflectance spectra have been measured for a series of samples of Carrara marble experimentally deformed under different cylindrical stress ( P = 0, 100, 250, 500, 980 bars). The creation of point defects that results has been shown up classically by irradiation with β rays (40 krads), thus producing a typical blue coloration linked with the formation of colour centres. The diffuse-reflectance spectra, measured on powders with a microscope-spectrometer in the visible range (400-800 nm), allow the determination of the absorption spectra by means of the Kubelka-Munk function. These absorption spectra have been measured for each of the deformed samples, as well as for different fractions of a very deformed specimen subsequently heated at temperatures between 100 and 500° C for a fixed time. In the same way, tectonised crystalline limestones, of various origins, were studied without any other treatment than the irradiation with β rays. From this study the following preliminary conclusions have been drawn: (1) The absorption spectrum of an undeformed but merely irradiated specimen of crystalline limestone is practically monotonous, but in the deformed specimens a broad band of absorption appears, having a maximum at 620 nm with several shoulders, the chief of which is at 520 nm. (2) This absorption band shows the existence of colour centres, the density of which can be estimated relatively by means of the chromaticity coordinates x and y of the C.I.E. obtained from the diffuse-reflectance spectra (C.I.E. = Commission Internationale de l'Éclairage). (3) An overgrinding of calcite generates defects that have the same spectra as those produced during the experimental deformation. Consequently, in obtaining the powders of grain size 50-80 μm needed for the diffuse spectrometry, great care must be exercised. (4) For a given confining pressure, the defect density is proportional to the deformation rate. (5) One can calibrate the effect of the annealing of

  15. A study of variations in the 787-nm ammonia absorption band in the Jupiter atmosphere

    NASA Astrophysics Data System (ADS)

    Bondarenko, N. N.

    2013-08-01

    During the last years the program of the spectrophotometric study of Jupiter included the measurements of the NH3 absorption band 787 nm. This band is overlapped by a broader absorption band of CH4. To detect the NH3 band we used the ratio of Jovian spectra to the spectrum of Saturn equatorial region. It was taken into account that the ammonia absorption on Saturn is significantly weaker than on Jupiter. The results of processing the spectrograms were analyzed for the years 2007-2010. Latitudinal variations of the NH3 band regularly show a depression of absorption at low and temperate latitudes of Jovian northern hemisphere. The equivalent width decreases approximately from 18-16 Å, to 14-12 Å. A more or less symmetric and steeper decrease of absorption from the disk center to limbs was obtained for the equatorial belt of Jupiter. It may be considered as evidence of the reality of that latitudinal depression but not the instrumental errors. It should be noted that the ammonia decrease in northern hemisphere was detected also from radio observations of Jupiter

  16. Ultra-violet and visible absorption characterization of explosives by differential reflectometry

    NASA Astrophysics Data System (ADS)

    Dubroca, Thierry; Moyant, Kyle; Hummel, Rolf E.

    2013-03-01

    This study presents some optical properties of TNT (2,4,6-trinitrotoluene), RDX, HMX and tetryl, specifically their absorption spectra as a function of concentration in various solvents in the ultraviolet and visible portion of the electromagnetic spectrum. We utilize a standoff explosives detection method, called differential reflectometry (DR). TNT was diluted in six different solvents (acetone, acetonitrile, ethanol, ethyl acetate, methanol, and toluene), which allowed for a direct comparison of absorption features over a wide range of concentrations. A line-shape analysis was adopted with great accuracy (R2 > 0.99) to model the absorption features of TNT in differential reflectivity spectra. We observed a blue shift in the pertinent absorption band with decreasing TNT concentration for all solvents. Moreover, using this technique, it was found that for all utilized solvents the concentration of TNT as well as of RDX, HMX, and tetryl, measured as a function of the transition wavelength of the ultra-violet absorption edge in differential reflectivity spectra shows three distinct regions. A model is presented to explain this behavior which is based on intermolecular hydrogen bonding of explosives molecules with themselves (or lack thereof) at different concentrations. Other intermolecular forces such as dipole-dipole interactions, London dispersion forces and π-stacking contribute to slight variations in the resulting spectra, which were determined to be rather insignificant in comparison to hydrogen bonding. The results are aimed towards a better understanding of the DR spectra of explosives energetic materials.

  17. Ultra-violet and visible absorption characterization of explosives by differential reflectometry.

    PubMed

    Dubroca, Thierry; Moyant, Kyle; Hummel, Rolf E

    2013-03-15

    This study presents some optical properties of TNT (2,4,6-trinitrotoluene), RDX, HMX and tetryl, specifically their absorption spectra as a function of concentration in various solvents in the ultraviolet and visible portion of the electromagnetic spectrum. We utilize a standoff explosives detection method, called differential reflectometry (DR). TNT was diluted in six different solvents (acetone, acetonitrile, ethanol, ethyl acetate, methanol, and toluene), which allowed for a direct comparison of absorption features over a wide range of concentrations. A line-shape analysis was adopted with great accuracy (R(2)>0.99) to model the absorption features of TNT in differential reflectivity spectra. We observed a blue shift in the pertinent absorption band with decreasing TNT concentration for all solvents. Moreover, using this technique, it was found that for all utilized solvents the concentration of TNT as well as of RDX, HMX, and tetryl, measured as a function of the transition wavelength of the ultra-violet absorption edge in differential reflectivity spectra shows three distinct regions. A model is presented to explain this behavior which is based on intermolecular hydrogen bonding of explosives molecules with themselves (or lack thereof) at different concentrations. Other intermolecular forces such as dipole-dipole interactions, London dispersion forces and π-stacking contribute to slight variations in the resulting spectra, which were determined to be rather insignificant in comparison to hydrogen bonding. The results are aimed towards a better understanding of the DR spectra of explosives energetic materials.

  18. Direct and quantitative broadband absorptance spectroscopy with multilayer cantilever probes

    SciTech Connect

    Hsu, Wei-Chun; Tong, Jonathan Kien-Kwok; Liao, Bolin; Chen, Gang

    2015-04-21

    A system for measuring the absorption spectrum of a sample is provided that includes a broadband light source that produces broadband light defined within a range of an absorptance spectrum. An interferometer modulates the intensity of the broadband light source for a range of modulation frequencies. A bi-layer cantilever probe arm is thermally connected to a sample arm having at most two layers of materials. The broadband light modulated by the interferometer is directed towards the sample and absorbed by the sample and converted into heat, which causes a temperature rise and bending of the bi-layer cantilever probe arm. A detector mechanism measures and records the deflection of the probe arm so as to obtain the absorptance spectrum of the sample.

  19. Wideband digital spectrum analyzer

    NASA Technical Reports Server (NTRS)

    Morris, G. A., Jr.; Wilck, H. C.

    1979-01-01

    Modular spectrum analyzer consisting of RF receiver, fast fourier transform spectrum analyzer, and data processor samples stochastic signals in 220 channels. Construction reduces design and fabrication costs of assembled unit.

  20. Autism Spectrum Disorder (ASD)

    MedlinePlus

    ... spectrum disorder (ASD) is a group of developmental disabilities that can cause significant social, communication and behavioral ... for autism spectrum disorder (ASD) and other developmental disabilities. More E-mail Your Friends "Children with autism ...

  1. Investigations on nonlinear absorption and nonlinear refraction of a new photonic crystal using Z-scan

    NASA Astrophysics Data System (ADS)

    Shetty, T. C. S.; Sandeep, K. M.; Mascarenhas, N. P.; Dharmaprakash, S. M.

    2016-05-01

    A new photonic material, (2E)-1-(3-chlorophenyl)-3-(2,4-dichlorophenyl)prop-2-en-1-one (DCPP) was synthesized and crystallised at room temperature. The functional groups of synthesised material were confirmed using FT-IR. The third order nonlinear optical (NLO) properties were investigated using Z-scan technique with 5 ns Nd:YAG laser pulses operating at a wavelength of 532 nm. Linear absorption spectrum of DCPP crystals shows an optical transmittance window and a lower cutoff wavelength of absorption at 380 nm. The direct transition band gap energy was determined using Tauc's plot. The melting point and thermal stability of the crystal have been investigated by thermo gravimetric analysis/differential thermal analysis (TGA/DTA). The Thermo gravimetric curve showed absence of any phase transition before melting point.

  2. 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.

  3. Nuclear quantum effects in the structure and lineshapes of the N2 NEXAFS spectrum

    SciTech Connect

    Fatehi, Shervin; Schwartz, Craig P.; Saykally, Richard J.; Prendergast, David

    2009-12-04

    We study the relative ability of several models of the X-ray absorption spectrum to capture the Franck-Condon structure apparent from an experiment on gaseous nitrogen. In doing so, we adopt the Born-Oppenheimer approximation and a constrained density functional theory method for computing the energies of the X-ray-excited molecule. Starting from an otherwise classical model for the spectrum, we systematically introduce more realistic physics, first by substituting the quantum mechanical nuclear radial density in the bond separation R for the classical radial density, then by adding the effect of zero-point energy and other level shifts, and finally by including explicit rovibrational quantization of both the ground and excited states. The quantization is determined exactly, using a discrete variable representation. We show that the NEXAFS spectrum can be predicted semiquantiatively within this framework. We also address the possibility of non-trivial temperature dependence in the spectrum. Finally, we show that it is possible to improve the predicted spectrum by using constrained DFT in combination with more accurate potentials.

  4. Simplified Digital Spectrum Analyzer

    NASA Technical Reports Server (NTRS)

    Cole, Steven W.

    1992-01-01

    Spectrum analyzer computes approximate cross-correlations between noisy input signal and reference signal of known frequency, yielding measure of amplitude of sinusoidal component of input. Complexity and power consumed less than other digital spectrum analyzers. Performs no multiplications, and because processes data on each frequency independently, focuses on narrow spectral range without processing data on rest of spectrum.

  5. [Transient UV absorption spectra of artemisinin reacting with sodium hydroxide].

    PubMed

    Gao, Yan-Jun; Ping, Li; Yang, Li-Jun; Wang, Qi-Ming; Xue, Jun-Peng; Wu, Da-Cheng; Li, Rui-Xia

    2009-03-01

    UV absorption spectrum of artemisinin and transient absorption spectra of various concentrations of artemisinin reacting with sodium hydroxide were measured by using an intensified spectroscopic detector ICCD. The exposure time of each spectrum was 0.1 ms. Results indicate that artemisinin has an obvious UV absorption band centered at 212.52 nm and can react with sodium hydroxide easily. All absorption spectra of different concentrations of artemisinin reacting with sodium hydroxide have the similar changes, but the moment at which the changes happened is different. After adding sodium hydroxide into artemisinin in ethanol solution, there was a new absorption band centered at 288 nm appearing firstly. As reaction went on, the intensity of another absorption band centered at 260 nm increased gradually. At the end of the reaction, a continuous absorption band from 200 to 350 nm with the peak at 245 nm formed finally. No other transient absorption spectral data are available on the reaction of artemisinin with sodium hydroxide currently. The new spectral information obtained in this experiment provides very important experimental basis for understanding the properties of artemisinin reacting with alkaline medium and is useful for correctly using of artemisinin as a potential anticancer drug.

  6. On the NH3 absorption depression observable at Northern low latitudes of Jupiter

    NASA Astrophysics Data System (ADS)

    Tejfel, Victor G.; Vdovichenko, Vladimir D.; Lysenko, Peter G.; Karimov, Alibek M.; Kirienko, Galina A.; Bondarenko, Natalya N.; Kharitonova, Galina

    2016-10-01

    From February to April of 2016, we carried out a special series of spectrophotometric observations of Jupiter to study the current behavior of the ammonia absorption at the low latitudes of the Northern hemisphere, where in 2004 we have found a well-defined depression of the 787 nm NH3 absorption band intensity (V.Tejfel et al., Bull.AAS, 2005, Vol. 37, p.682). In subsequent years, an existence of this depression was annually confirmed by spectral observations, although we were noticing its variable character. During observations of 2016 we obtained more than 2,500 CCD-spectrograms, including the spectra of the central meridian, the GRS, and 12 scans of Jovian disk on different dates (70 zonal spectra in each scan). The 787 nm NH3 absorption band was extracted with using of ratios of the Jovian spectra to the Saturn's disk spectrum that was taken as a reference. The depression of absorption in this band begins almost from the equator, and its maximum occurs at the planetographic latitude of 100N then the absorption increases again approaching to the latitude of 200N. The equivalent bandwidths corresponding to these latitudes are equal to 18.7 ± 1.4 A, 14.4 ± 1.0 A and 17.8 ± 0.8A. The 645 nm NH3 absorption band also shows depletion at the low latitudes of the Northern hemisphere, but it is less pronounced. At the temperate latitudes of the Northern hemisphere this band's absorption is systematically lower than the Southern Hemisphere's ones. We will continue research in this direction, especially because recently a significant depletion of gaseous NH3 has also been found with using of the VLA with high resolution (I. de Pater et al., Science, 2016, Vol. 352, Issue 6290, p.1290-1294) at the low latitudes of the Northern hemisphere in the region of the NEB.

  7. [Influence of silver/silicon dioxide on infrared absorption spectroscopy of sodium nitrate].

    PubMed

    Yang, Shi-Ling; Yue, Li; Jia, Zhi-Jun

    2014-09-01

    Quickly detecting of ocean nutrient was one important task in marine pollution monitoring. We discovered the application of surface-enhanced infrared absorption spectroscopy in the detection of ocean nutrient through researching the evaporation of sodium nitrate solution. The silicon dioxide (SiO2) with highly dispersion was prepared by Stober method, The silver/silica (Ag/SiO2) composite materials were prepared by mixing ammonia solution and silicon dioxide aqueous solution. Three kinds of composite materials with different surface morphology were fabricated through optimizing the experimental parameter and changing the experimental process. The surface morphology, crystal orientation and surface plasmon resonance were investigated by means of the scanning electronic microscope (SEM), X-ray diffraction (XRD), UV-Visible absorption spectrum and infrared ab- sorption spectroscopy. The SEM images showed that the sample A was purified SiO2, sample B and sample C were mixture of silver nanoparticle and silicon dioxide, while sample D was completed nanoshell structure. The absorption spectroscopy showed that there was surface plasmon resonance in the UV-visible region, while there was possibility of surface plasmon resonance in the Infrared absorption region. The effect of Ag/SiO2 composite material on the infrared absorption spectra of sodium nitrite solution was investigated through systematically analyzing the infrared absorption spectroscopy of sodium nitrate solution during its evaporation, i. e. the peak integration area of nitrate and the peak integration area of water molecule. The experimental results show that the integration area of nitrate was enhanced greatly during the evaporation process while the integration area of water molecule decreased continuously. The integration area of nitrate comes from the anti-symmetric stretch vibration and the enhancement of the vibration is attributed to the interface effect of Ag/SiO2 which is consistent with Jensen T

  8. [Study of the Detecting System of CH4 and SO2 Based on Spectral Absorption Method and UV Fluorescence Method].

    PubMed

    Wang, Shu-tao; Wang, Zhi-fang; Liu, Ming-hua; Wei, Meng; Chen, Dong-ying; Wang, Xing-long

    2016-01-01

    According to the spectral absorption characteristics of polluting gases and fluorescence characteristics, a time-division multiplexing detection system is designed. Through this system we can detect Methane (CH4) and sulfur dioxide (SO2) by using spectral absorption method and the SO2 can be detected by using UV fluorescence method. The system consists of four parts: a combination of a light source which could be switched, the common optical path, the air chamber and the signal processing section. The spectral absorption characteristics and fluorescence characteristics are measured first. Then the experiment of detecting CH4 and SO2 through spectral absorption method and the experiment of detecting SO2 through UV fluorescence method are conducted, respectively. Through measuring characteristics of spectral absorption and fluorescence, we get excitation wavelengths of SO2 and CH4 measured by spectral absorption method at the absorption peak are 280 nm and 1.64 μm, respectively, and the optimal excitation wavelength of SO2 measured by UV fluorescence method is 220 nm. we acquire the linear relation between the concentration of CH4 and relative intensity and the linear relation between the concentration of SO2 and output voltage after conducting the experiment of spectral absorption method, and the linearity are 98.7%, 99.2% respectively. Through the experiment of UV fluorescence method we acquire that the relation between the concentration of SO2 and the voltage is linear, and the linearity is 99.5%. Research shows that the system is able to be applied to detect the polluted gas by absorption spectrum method and UV fluorescence method. Combing these two measurement methods decreases the costing and the volume, and this system can also be used to measure the other gases. Such system has a certain value of application. PMID:27228784

  9. [Study of the Detecting System of CH4 and SO2 Based on Spectral Absorption Method and UV Fluorescence Method].

    PubMed

    Wang, Shu-tao; Wang, Zhi-fang; Liu, Ming-hua; Wei, Meng; Chen, Dong-ying; Wang, Xing-long

    2016-01-01

    According to the spectral absorption characteristics of polluting gases and fluorescence characteristics, a time-division multiplexing detection system is designed. Through this system we can detect Methane (CH4) and sulfur dioxide (SO2) by using spectral absorption method and the SO2 can be detected by using UV fluorescence method. The system consists of four parts: a combination of a light source which could be switched, the common optical path, the air chamber and the signal processing section. The spectral absorption characteristics and fluorescence characteristics are measured first. Then the experiment of detecting CH4 and SO2 through spectral absorption method and the experiment of detecting SO2 through UV fluorescence method are conducted, respectively. Through measuring characteristics of spectral absorption and fluorescence, we get excitation wavelengths of SO2 and CH4 measured by spectral absorption method at the absorption peak are 280 nm and 1.64 μm, respectively, and the optimal excitation wavelength of SO2 measured by UV fluorescence method is 220 nm. we acquire the linear relation between the concentration of CH4 and relative intensity and the linear relation between the concentration of SO2 and output voltage after conducting the experiment of spectral absorption method, and the linearity are 98.7%, 99.2% respectively. Through the experiment of UV fluorescence method we acquire that the relation between the concentration of SO2 and the voltage is linear, and the linearity is 99.5%. Research shows that the system is able to be applied to detect the polluted gas by absorption spectrum method and UV fluorescence method. Combing these two measurement methods decreases the costing and the volume, and this system can also be used to measure the other gases. Such system has a certain value of application.

  10. [The nitrate and temperature impact analysis in the detection of COD by UV spectrum].

    PubMed

    Bi, Wei-Hong; Li, Jian-Guo; Wu, Guo-Qing; Fu, Xing-Hu; Fu, Guang-Wei

    2014-03-01

    Configured standard solution of chemical oxygen demand with potassium hydrogen phthalate was used as experimental subjects, collected ultraviolet absorption spectra of the standard solution in the range of 1,800 mg x L(-1), were collected, and PLS (partial least squares) algorithm was used to establish the correction model of different spectral region, the results showed that. The model in the spectral region of 265-310 nm had the highest correlation and smallest error; In order to eliminate the impact of nitrates and temperature on the detection of the COD , studied the changes of the UV absorption spectrum with different concentrations of sodium standard solution and different temperature. The results showed that absorption of nitrate in 208-238 nm was apparent, and the model for spectral region of 265-310 nm was free from the influence of nitrate; In the full range of spectrum, temperature rising leads to an increase in absorbance, thus the temperature compensation model was established for the different spectral region through predictive analysis.

  11. Absorption mode FTICR mass spectrometry imaging.

    PubMed

    Smith, Donald F; Kilgour, David P A; Konijnenburg, Marco; O'Connor, Peter B; Heeren, Ron M A

    2013-12-01

    Fourier transform ion cyclotron resonance mass spectrometry offers the highest mass resolving power for molecular imaging experiments. This high mass resolving power ensures that closely spaced peaks at the same nominal mass are resolved for proper image generation. Typically higher magnetic fields are used to increase mass resolving power. However, a gain in mass resolving power can also be realized by phase correction of the data for absorption mode display. In addition to mass resolving power, absorption mode offers higher mass accuracy and signal-to-noise ratio over the conventional magnitude mode. Here, we present the first use of absorption mode for Fourier transform ion cyclotron resonance mass spectrometry imaging. The Autophaser algorithm is used to phase correct each spectrum (pixel) in the image, and then, these parameters are used by the Chameleon work-flow based data processing software to generate absorption mode "Datacubes" for image and spectral viewing. Absorption mode reveals new mass and spatial features that are not resolved in magnitude mode and results in improved selected ion image contrast.

  12. 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.

  13. New polarisation effects in saturated absorption spectroscopy in the field of counterpropagating light waves

    NASA Astrophysics Data System (ADS)

    Brazhnikov, D. V.; Novokreshchenov, V. K.; Ignatovich, S. M.; Taichenachev, A. V.; Yudin, V. I.

    2016-05-01

    The effect of a double structure of saturated absorption resonance in the field of counterpropagating light waves interacting with atomic gas is considered, which was first studied experimentally and theoretically by Vasil'ev et al. [V.V. Vasil'ev et al., J. Exp. Theor. Phys., 112, 770 (2011)]. The effect manifests itself as a new nonlinear resonance formed as a peak in the absorption spectrum of the probe wave. The resonance is observed inside a 'conventional' dip in the spectrum of saturated absorption. Previously, this effect was theoretically described only in the frameworks of the two-level atomic model, i.e., without making allowance for degeneracy of atomic energy levels with respect to the projection of the total angular momentum and for the vector nature of light. We extend the theory of the effect to the case of real atomic systems with degenerate energy levels and arbitrary polarisations of light waves. In particular, on an example of the simple transition Fg = 1 → Fe = 0 we show that polarisation parameters of light waves may significantly affect the contrast of the new effect and the possibility of observing it at all. Conclusions of the work are confirmed both analytically and bnumerically.

  14. Absorption of ultraviolet radiation by antarctic phytoplankton

    SciTech Connect

    Vernet, M.; Mitchell, B.G. )

    1990-01-09

    Antarctic phytoplankton contain UV-absorbing compounds that may block damaging radiation. Compounds that absorb from 320-340 nm were observed in spectral absorption of both particulates and in methanol extracts of the particulates. The decrease in the total concentration of these UV compounds with respect to chlorophyll a, as measured by the ratio of in vitro absorption at 335 nm to absorption at 665 nm is variable and decreases with depth. We observed up to 5-fold decrease in this ratio for samples within the physically mixes surface layer. The absorption of UV radiation in methanol extracts, which peaks from 320 to 340 nm, may be composed of several compounds. Shifts in peak absorption with depth (for example, from 331 nm at surface to 321 nm at 75 m), may be interpreted as a change in composition. Ratios of protective yellow xanthophylls (diadinoxanthin + diatoxanthin) to photosynthetic fucoxanthin-like pigments have highest values in surface waters. As these pigments also absorb in the near UV, their function might extend to protection as well as utilization of UV radiation for photosynthesis. We document strong absorption in the UV from 320-330 nm for Antarctic marine particulates. Below this region of the solar energy spectrum, absolute energy levels of incident radiation drop off dramatically. Only wavelengths shorter than about 320 nm will be significantly enhanced due to ozone depletion. If the absorption we observed serves a protective role for phytoplankton photosynthesis, it appears the peak band is in the region where solar energy increases rapidly, and not in the region where depletion would cause significant variations in absolute flux.

  15. Absorption of solar radiation by clouds: observations versus models.

    PubMed

    Cess, R D; Zhang, M H; Minnis, P; Corsetti, L; Dutton, E G; Forgan, B W; Garber, D P; Gates, W L; Hack, J J; Harrison, E F; Jing, X; Kiehi, J T; Long, C N; Morcrette, J J; Potter, G L; Ramanathan, V; Subasilar, B; Whitlock, C H; Young, D F; Zhou, Y

    1995-01-27

    There has been a long history of unexplained anomalous absorption of solar radiation by clouds. Collocated satellite and surface measurements of solar radiation at five geographically diverse locations showed significant solar absorption by clouds, resulting in about 25 watts per square meter more global-mean absorption by the cloudy atmosphere than predicted by theoretical models. It has often been suggested that tropospheric aerosols could increase cloud absorption. But these aerosols are temporally and spatially heterogeneous, whereas the observed cloud absorption is remarkably invariant with respect to season and location. Although its physical cause is unknown, enhanced cloud absorption substantially alters our understanding of the atmosphere's energy budget.

  16. Absorption of Solar Radiation by Clouds: Observations Versus Models

    NASA Technical Reports Server (NTRS)

    Cess, R. D.; Zhang, M. H.; Minnis, P.; Corsetti, L.; Dutton, E. G.; Forgan, B. W.; Garber, D. P.; Gates, W. L.; Hack, J. J.; Harrison, E. F.; Jing, X.; Kiehl, J. T.; Long, C. N.; Morcrette, J.-J.; Potter, G. L.; Ramanathan, V.; Subasilar, B.; Whitlock, C. H.; Young, D. F.; Zhou, Y.

    1995-01-01

    There has been a long history of unexplained anomalous absorption of solar radiation by clouds. Collocated satellite and surface measurements of solar radiation at five geographically diverse locations showed significant solar absorption by clouds, resulting in about 25 watts per square meter more global-mean absorption by the cloudy atmosphere than predicted by theoretical models. It has often been suggested that tropospheric aerosols could increase cloud absorption. But these aerosols are temporally and spatially heterogeneous, whereas the observed cloud absorption is remarkably invariant with respect to season and location. Although its physical cause is unknown, enhanced cloud absorption substantially alters our understanding of the atmosphere's energy budget.

  17. Narrowband spread spectrum systems

    NASA Astrophysics Data System (ADS)

    Annecke, K. H.; Ottka, M.

    1984-10-01

    The available military radio frequency bands are covered very densely by the already existing conventional systems and therefore the application of bandwidth widening procedures as antijam measures will be allowed only with small spreading factors within these RF-bands. The problems arising from the random code selection for spread spectrum systems with small spreading factors are discussed. The calculations show the dependence between certain statistical properties of classes of codewords and the number of codewords available in these classes. The bit error probabilities in case of jamming by white Gaussian noise, narrowband and CW-jammers are calculated in comparison with the error probability of the class of codewords with ideal correlation properties.

  18. Ocean color spectrum calculations

    NASA Technical Reports Server (NTRS)

    Mccluney, W. R.

    1974-01-01

    There is obvious value in developing the means for measuring a number of subsurface oceanographic parameters using remotely sensed ocean color data. The first step in this effort should be the development of adequate theoretical models relating the desired oceanographic parameters to the upwelling radiances to be observed. A portion of a contributory theoretical model can be described by a modified single scattering approach based on a simple treatment of multiple scattering. The resulting quasisingle scattering model can be used to predict the upwelling distribution of spectral radiance emerging from the sea. The shape of the radiance spectrum predicted by this model for clear ocean water shows encouraging agreement with measurements made at the edge of the Sargasso Sea off Cape Hatteras.

  19. Clinical neurogenetics: autism spectrum disorders.

    PubMed

    Mehta, Sunil Q; Golshani, Peyman

    2013-11-01

    Autism spectrum disorders are neurodevelopmental disorders characterized by deficits in social interactions, communication, and repetitive or restricted interests. There is strong evidence that de novo or inherited genetic alterations play a critical role in causing Autism Spectrum Disorders, but non-genetic causes, such as in utero infections, may also play a role. Magnetic resonance imaging based and autopsy studies indicate that early rapid increase in brain size during infancy could underlie the deficits in a large subset of subjects. Clinical studies show benefits for both behavioral and pharmacological treatment strategies. Genotype-specific treatments have the potential for improving outcome in the future.

  20. Spectrum analysis in beam diagnostics

    SciTech Connect

    Zhang, S.Y.; Weng, W.T.

    1993-04-23

    In this article, we discuss fundamentals of the spectrum analysis in beam diagnostics, where several important particle motions in a circular accelerator are considered. The properties of the Fourier transform are presented. Then the coasting and the bunched beam motion in both longitudinal and transverse are studied. The discussions are separated for the signal particle, multiple particle, and the Schottky noise cases. To demonstrate the interesting properties of the beam motion spectrum, time domain functions are generated, and then the associated spectra are calculated and plotted. In order to show the whole picture in a single plot, some data have been scaled, therefore they may not be realistic in an accelerator.

  1. 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.

  2. Novel absorption detection techniques for capillary electrophoresis

    SciTech Connect

    Xue, Y.

    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 {mu}M 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.

  3. Creating semiconductor metafilms with designer absorption spectra.

    PubMed

    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

  4. 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

  5. Creating semiconductor metafilms with designer absorption spectra

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    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.

  6. Emission from water vapor and absorption from other gases at 5-7.5 μm in Spitzer-IRS Spectra Of Protoplanetary Disks

    SciTech Connect

    Sargent, B. A.; Forrest, W.; Watson, Dan M.; Kim, K. H.; Richter, I.; Tayrien, C.; D'Alessio, P.; Calvet, N.; Furlan, E.; Green, J.; Pontoppidan, K.

    2014-09-10

    We present spectra of 13 T Tauri stars in the Taurus-Auriga star-forming region showing emission in Spitzer Space Telescope Infrared Spectrograph 5-7.5 μm spectra from water vapor and absorption from other gases in these stars' protoplanetary disks. Seven stars' spectra show an emission feature at 6.6 μm due to the ν{sub 2} = 1-0 bending mode of water vapor, with the shape of the spectrum suggesting water vapor temperatures >500 K, though some of these spectra also show indications of an absorption band, likely from another molecule. This water vapor emission contrasts with the absorption from warm water vapor seen in the spectrum of the FU Orionis star V1057 Cyg. The other 6 of the 13 stars have spectra showing a strong absorption band, peaking in strength at 5.6-5.7 μm, which for some is consistent with gaseous formaldehyde (H{sub 2}CO) and for others is consistent with gaseous formic acid (HCOOH). There are indications that some of these six stars may also have weak water vapor emission. Modeling of these stars' spectra suggests these gases are present in the inner few AU of their host disks, consistent with recent studies of infrared spectra showing gas in protoplanetary disks.

  7. The Optical Spectrum of the Geminga Pulsar

    NASA Technical Reports Server (NTRS)

    Martin, Christopher; Halpern, Jules P.; Schiminovich, David; Oliversen, Ronald (Technical Monitor)

    2001-01-01

    We obtained an optical spectrum of the isolated pulsar Geminga at the Keck Observatory. The optical object is at the limit of spectroscopic capability of any telescope, with a continuum flux that is approx. 0.5% of the dark sky on Mauna Kea. With particular attention paid to the dominant systematics of sky subtraction in our observing and analysis methods, we attained approx. 0.1% systematics in heavily binned spectra. The resulting spectrum spanning 3700 - 8000 A has a flat power-law shape f(sub nu) proportional to nu(exp -0.8) and a broad dip over 6300 - 6500 A. Thermal radiation cannot explain the optical spectrum of Geminga. The dominant component can be modeled as either electron synchrotron emission and ion (proton) cyclotron absorption, or ion cyclotron emission, the latter in a 10(exp 11) G magnetic field.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Investigation of linear optical absorption coefficients in core-shell quantum dot (QD) luminescent solar concentrators (LSCs)

    NASA Astrophysics Data System (ADS)

    Ebrahimipour, Bahareh Alsadat; Askari, Hassan Ranjbar; Ramezani, Ali Behjat

    2016-09-01

    The interlevel absorption coefficient of CdSe/ZnS and ZnS/CdSe core-shell Quantum Dot (QD) in luminescent solar concentrators (LSCs) is reported. By considering the quantum confinement effects, the wave functions and eigenenergies of electrons in the nonperturebative system consists of a core-shell QD have been numerically calculated under the frame work of effective-mass approximation by solving a three-dimensional Schrӧdinger equation. And then the absorption coefficient is obtained under density matrix approximation considering in the polymer sheets of the concentrator including the core-shell QDs. The effect of the hetero-structure geometry upon the energy spectrum and absorption coefficient associated to interlevel transitions was also considered. The results show that the core-shell QDs can absorb the photons with higher energy in solar spectrum as compared to the inverted core-shell. And with a small shell layer diameter, the core-shell QDs produce larger linear absorption coefficients and consequently higher efficiency values, however it is inversed for inverted core-shell QDs. The work described here gives a detailed insight into the promise of QD-based LSCs and the optoelectronic devices applications.

  15. Absorption Features in Spectra of Magnetized Neutron Stars

    SciTech Connect

    Suleimanov, V.; Hambaryan, V.; Neuhaeuser, R.; Potekhin, A. Y.; Pavlov, G. G.; Adelsberg, M. van; Werner, K.

    2011-09-21

    The X-ray spectra of some magnetized isolated neutron stars (NSs) show absorption features with equivalent widths (EWs) of 50-200 eV, whose nature is not yet well known.To explain the prominent absorption features in the soft X-ray spectra of the highly magnetized (B{approx}10{sup 14} G) X-ray dim isolated NSs (XDINSs), we theoretically investigate different NS local surface models, including naked condensed iron surfaces and partially ionized hydrogen model atmospheres, with semi-infinite and thin atmospheres above the condensed surface. We also developed a code for computing light curves and integral emergent spectra of magnetized neutron stars with various temperature and magnetic field distributions over the NS surface. We compare the general properties of the computed and observed light curves and integral spectra for XDINS RBS 1223 and conclude that the observations can be explained by a thin hydrogen atmosphere above the condensed iron surface, while the presence of a strong toroidal magnetic field component on the XDINS surface is unlikely.We suggest that the harmonically spaced absorption features in the soft X-ray spectrum of the central compact object (CCO) 1E 1207.4-5209 (hereafter 1E 1207) correspond to peaks in the energy dependence of the free-free opacity in a quantizing magnetic field, known as quantum oscillations. To explore observable properties of these quantum oscillations, we calculate models of hydrogen NS atmospheres with B{approx}10{sup 10}-10{sup 11} G(i.e., electron cyclotron energy E{sub c,e}{approx}0.1-1 keV) and T{sub eff} = 1-3 MK. Such conditions are thought to be typical for 1E 1207. We show that observable features at the electron cyclotron harmonics with EWs {approx_equal}100-200 eV can arise due to these quantum oscillations.

  16. Impact of different visible light spectra on oxygen absorption and surface discoloration of bologna sausage.

    PubMed

    Böhner, Nadine; Rieblinger, Klaus

    2016-11-01

    The objective of this study was to evaluate the influence of several visible light spectra in various intensities on the oxygen absorption and surface color of sliced bologna. Sausage samples were stored in a gastight model packaging system and illuminated at 5°C with six single-colored LEDs covering the main part of the visible light spectrum. The initial oxygen level was set at 0.5% in order to simulate common residual oxygen amounts in conventional packaging. The oxygen absorption and the discoloration measured as changes in CIE a*-value were dependent from the applied light intensity. The color stability of bologna was differently affected by light of various wavelengths. The results show that the use of suitable LEDs with specific spectra for display illumination can help to reduce the light induced deterioration of cured sausages in retail markets. PMID:27343458

  17. Chemical Sensitivity of the Sulfur K-Edge X-ray Absorption Spectra of Organic Disulfides.

    PubMed

    Pickering, Ingrid J; Barney, Monica; Cotelesage, Julien J H; Vogt, Linda; Pushie, M Jake; Nissan, Andrew; Prince, Roger C; George, Graham N

    2016-09-22

    Sulfur K-edge X-ray absorption spectroscopy increasingly is used as a tool to provide speciation information about the sulfur chemical form in complex samples, with applications ranging from fossil fuels to soil science to health research. As part of an ongoing program of systematic investigations of the factors that affect the variability of sulfur K near-edge spectra, we have examined the X-ray absorption spectra of a series of organic symmetric disulfide compounds. We have used polarized sulfur K-edge spectra of single crystals of dibenzyl disulfide to confirm the assignments of the major transitions in the spectrum as 1s → (S-S)σ* and 1s → (S-C)σ*. We also have examined the solution spectra of an extended series of disulfides and show that the spectra change in a systematic and predictable manner with the nature of the external group. PMID:27571342

  18. Performance Enhancement of Polymer Solar Cells by Using Two Polymer Donors with Complementary Absorption Spectra.

    PubMed

    Lu, Heng; Zhang, Xuejuan; Li, Cuihong; Wei, Hedi; Liu, Qian; Li, Weiwei; Bo, Zhishan

    2015-07-01

    Performance enhancement of polymer solar cells (PSCs) is achieved by expanding the absorption of the active layer of devices. To better match the spectrum of solar radiation, two polymers with different band gaps are used as the donor material to fabricate ternary polymer cells. Ternary blend PSCs exhibit an enhanced short-circuit current density and open-circuit voltage in comparison with the corresponding HD-PDFC-DTBT (HD)- and DT-PDPPTPT (DPP)-based binary polymer solar cells, respectively. Ternary PSCs show a power conversion efficiency (PCE) of 6.71%, surpassing the corresponding binary PSCs. This work demonstrates that the fabrication of ternary PSCs by using two polymers with complementary absorption is an effective way to improve the device performance.

  19. Phase-dependent multiple optomechanically induced absorption in multimode optomechanical systems with mechanical driving

    NASA Astrophysics Data System (ADS)

    Jiang, Cheng; Cui, Yuanshun; Bian, Xintian; Zuo, Fen; Yu, Hualing; Chen, Guibin

    2016-08-01

    We investigate theoretically the response of the output field from an optomechanical system consisting of N nearly degenerate mechanical resonators each coupled to a common cavity mode. When the cavity is driven simultaneously by a strong control field and a weak probe field and each mechanical resonator is driven by a coherent mechanical pump, we obtain the analytical expression for the probe transmission. We show that the probe transmission spectrum can exhibit multiple optomechanically induced absorption (OMIA) with at most N narrow absorption dips, which can be tuned by the phase and amplitude of the mechanical driving field as well as the control field. Moreover, it is shown that the peak probe transmission can be enhanced or suppressed by increasing the amplitude of the mechanical pump, which depends on the phase difference. This phase-dependent effect plays an important role in controlling the propagation of the probe field between OMIA and parametric amplification.

  20. Synthesis of Photoresponsive Dual NIR Two-Photon Absorptive [60]Fullerene Triads and Tetrads

    PubMed Central

    Jeon, Seaho; Wang, Min; Tan, Loon-Seng; Cooper, Thomas; Hamblin, Michael R.; Chiang, Long Y.

    2013-01-01

    Broadband nonlinear optical (NLO) organic nanostructures exhibiting both ultrafast photoresponse and a large cross-section of two-photon absorption throughout a wide NIR spectrum may make them suitable for use as nonlinear biophotonic materials. We report here the synthesis and characterization of two C60-(antenna)x analogous compounds as branched triad C60(>DPAF-C18)(>CPAF-C2M) and tetrad C60(>DPAF-C18)(>CPAF-C2M)2 nanostructures. These compounds showed approximately equal extinction coefficients of optical absorption over 400–550 nm that corresponds to near-IR two-photon based excitation wavelengths at 780–1,100 nm. Accordingly, they may be utilized as potential precursor candidates to the active-core structures of photosensitizing nanodrugs for 2γ-PDT in the biological optical window of 800–1,050 nm. PMID:23941881

  1. Reassignment of the Iron (3) Absorption Bands in the Spectra of Mars

    NASA Technical Reports Server (NTRS)

    Sherman, D. M.

    1985-01-01

    Absorption features in the near-infrared and visible region reflectance spectra of Mars have been assigned to specific Fe (3+) crystal-field and o(2-) yields Fe(3+) charge transfer transitions. Recently, near-ultraviolet absorption spectra of iron oxides were obtained and the energies of o(2-) yields Fe(3+) charge-transfer (LMCT) transitions were determined from accurate SCF-X # alpha-SW molecular orbital calculations on (FeO6)(9-) and (FeO4)(5-) clusters. Both the theoretical and experimental results, together with existing data in the literature, show that some of the previous Fe(3+) band assignments in the spectra of Mars need to be revised. The theory of Fe(3+) spectra in minerals is discussed and applied to the spectrum of Mars.

  2. Impact of different visible light spectra on oxygen absorption and surface discoloration of bologna sausage.

    PubMed

    Böhner, Nadine; Rieblinger, Klaus

    2016-11-01

    The objective of this study was to evaluate the influence of several visible light spectra in various intensities on the oxygen absorption and surface color of sliced bologna. Sausage samples were stored in a gastight model packaging system and illuminated at 5°C with six single-colored LEDs covering the main part of the visible light spectrum. The initial oxygen level was set at 0.5% in order to simulate common residual oxygen amounts in conventional packaging. The oxygen absorption and the discoloration measured as changes in CIE a*-value were dependent from the applied light intensity. The color stability of bologna was differently affected by light of various wavelengths. The results show that the use of suitable LEDs with specific spectra for display illumination can help to reduce the light induced deterioration of cured sausages in retail markets.

  3. Intra-cavity absorption spectroscopy with narrow-ridge microfluidic quantum cascade lasers.

    PubMed

    Belkin, Mikhail A; Loncar, Marko; Lee, Benjamon G; Pflugl, Christian; Audet, Ross; Diehl, Laurent; Capasso, Federico; Bour, David; Corzine, Scott; Hofler, Gloria

    2007-09-01

    We demonstrate microfluidic laser intra-cavity absorption spectroscopy with mid-infrared lambda approximately 9mum quantum cascade lasers. A deepetched narrow ridge waveguide laser is placed in a microfluidic chamber. The evanescent tails of the laser mode penetrate into a liquid on both sides of the ridge. The absorption lines of the liquid modify the laser waveguide loss, resulting in significant changes in the laser emission spectrum and the threshold current. A volume of liquid as small as ~10pL may, in principle, be sufficient for sensing using the proposed technique. This method, similar to the related gas-phase technique, shows promise as a sensitive means of detecting chemicals in small volumes of solutions.

  4. Wave-number spectrum of electroencephalographic signals.

    PubMed

    O'Connor, S C; Robinson, P A; Chiang, A K I

    2002-12-01

    A recently developed, physiologically based continuum model of corticothalamic electrodynamics is used to derive the theoretical form of the electroencephalographic wave-number spectrum and its projection onto a one-dimensional recording array. The projected spectrum is found to consist of a plateau followed by regions of power-law decrease with various exponents, which are dependent on both model parameters and temporal frequency. The theoretical spectrum is compared with experimental results obtained in other studies, showing good agreement. The model provides a framework for understanding the nature of the spatial power spectrum by linking the underlying physiology with the large-scale dynamics of the brain. PMID:12513316

  5. Accelerating Spectrum Sharing Technologies

    SciTech Connect

    Juan D. Deaton; Lynda L. Brighton; Rangam Subramanian; Hussein Moradi; Jose Loera

    2013-09-01

    Spectrum sharing potentially holds the promise of solving the emerging spectrum crisis. However, technology innovators face the conundrum of developing spectrum sharing technologies without the ability to experiment and test with real incumbent systems. Interference with operational incumbents can prevent critical services, and the cost of deploying and operating an incumbent system can be prohibitive. Thus, the lack of incumbent systems and frequency authorization for technology incubation and demonstration has stymied spectrum sharing research. To this end, industry, academia, and regulators all require a test facility for validating hypotheses and demonstrating functionality without affecting operational incumbent systems. This article proposes a four-phase program supported by our spectrum accountability architecture. We propose that our comprehensive experimentation and testing approach for technology incubation and demonstration will accelerate the development of spectrum sharing technologies.

  6. Surface Material Analysis of the S-type Asteroids: Removing the Space Weathering Effect from Reflectance Spectrum

    NASA Technical Reports Server (NTRS)

    Ueda, Y.; Miyamoto, M.; Mikouchi, T.; Hiroi, T.

    2003-01-01

    Recent years, many researchers have been observing a lot of asteroid reflectance spectra in the UV, visible to NIR at wavelength region. Reflectance spectroscopy of asteroid at this range should bring us a lot of information about its surface materials. Pyroxene and olivine have characteristic absorption bands in this wavelength range. Low-Ca pyroxene has two absorption bands around 0.9 microns and 1.9 microns. The more Ca and Fe content, the longer both absorption band centers. On the other hand, reflectance spectrum of olivine has three complicated absorption bands around 1 m, and no absorption feature around 2 microns. In general, reflectance spectra of many asteroids that are considered to be silicate rich (i.e., S- and A type asteroids) show redder slope and more subdued absorption bands than those of terrestrial minerals and meteorites. These features are now believed to be caused by the space weathering effect, which is probably caused by micrometeorite bombardment and/or solar wind. This process causes nanophase reduced iron (npFe(sup 0)) particles near the surface of mineral grains, which leads the optical change. Therefore, the space weathering effect should be removed from asteroid reflectance spectra to compare with those of meteorite and terrestrial minerals. In this report, we will apply the expanded modified Gaussian model (MGM) to the reflectance spectra of S-type asteroids 7 Iris and 532 Herculina and compare them with those of meteorites.

  7. Absorption of surface acoustic waves by topological insulator thin films

    SciTech Connect

    Li, L. L.; Xu, W.

    2014-08-11

    We present a theoretical study on the absorption of the surface acoustic waves (SAWs) by Dirac electrons in topological insulator (TI) thin films (TITFs). We find that due to momentum and energy conservation laws, the absorption of the SAWs in TITFs can only be achieved via intra-band electronic transitions. The strong absorption can be observed up to sub-terahertz frequencies. With increasing temperature, the absorption intensity increases significantly and the cut-off frequency is blue-shifted. More interestingly, we find that the absorption of the SAWs by the TITFs can be markedly enhanced by the tunable subgap in the Dirac energy spectrum of the TI surface states. Such a subgap is absent in conventional two-dimensional electron gases (2DEGs) and in the gapless Dirac 2DEG such as graphene. This study is pertinent to the exploration of the acoustic properties of TIs and to potential application of TIs as tunable SAW devices working at hypersonic frequencies.

  8. A plant canopy light absorption model with application to wheat

    NASA Technical Reports Server (NTRS)

    Chance, J. E.; Lemaster, E. W.

    1977-01-01

    From the light absorption model the absorption of light in the photosynthetically active region of the spectrum was calculated for a Penjamo wheat crop for several situations including: (1) the percent absorption of the incident radiation by a canopy having a four layer structure; (2) the percent absorption of light by the individual layers within a four layer canopy and by the underlying soil; (3) the percent absorption of light by each vegetative canopy layer for variable sun angle; and (4) the cumulative solar energy absorbed by the developing wheat canopy as it progresses from a single layer through its growth stages to a three layer canopy. This calculation was also presented as a function of the leaf area index.

  9. 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.

  10. 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.

  11. The marine diversity spectrum

    PubMed Central

    Reuman, Daniel C; Gislason, Henrik; Barnes, Carolyn; Mélin, Frédéric; Jennings, Simon

    2014-01-01

    Distributions of species body sizes within a taxonomic group, for example, mammals, are widely studied and important because they help illuminate the evolutionary processes that produced these distributions. Distributions of the sizes of species within an assemblage delineated by geography instead of taxonomy (all the species in a region regardless of clade) are much less studied but are equally important and will illuminate a different set of ecological and evolutionary processes. We develop and test a mechanistic model of how diversity varies with body mass in marine ecosystems. The model predicts the form of the ‘diversity spectrum’, which quantifies the distribution of species' asymptotic body masses, is a species analogue of the classic size spectrum of individuals, and which we have found to be a new and widely applicable description of diversity patterns. The marine diversity spectrum is predicted to be approximately linear across an asymptotic mass range spanning seven orders of magnitude. Slope −0·5 is predicted for the global marine diversity spectrum for all combined pelagic zones of continental shelf seas, and slopes for large regions are predicted to lie between −0·5 and −0·1. Slopes of −0·5 and −0·1 represent markedly different communities: a slope of −0·5 depicts a 10-fold reduction in diversity for every 100-fold increase in asymptotic mass; a slope of −0·1 depicts a 1·6-fold reduction. Steeper slopes are predicted for larger or colder regions, meaning fewer large species per small species for such regions. Predictions were largely validated by a global empirical analysis. Results explain for the first time a new and widespread phenomenon of biodiversity. Results have implications for estimating numbers of species of small asymptotic mass, where taxonomic inventories are far from complete. Results show that the relationship between diversity and body mass can be explained from the dependence of predation behaviour

  12. Spectral Fingerprinting of Individual Cells Visualized by Cavity-Reflection-Enhanced Light-Absorption Microscopy

    PubMed Central

    Arai, Yoshiyuki; Yamamoto, Takayuki; Minamikawa, Takeo; Takamatsu, Tetsuro; Nagai, Takeharu

    2015-01-01

    The absorption spectrum of light is known to be a “molecular fingerprint” that enables analysis of the molecular type and its amount. It would be useful to measure the absorption spectrum in single cell in order to investigate the cellular status. However, cells are too thin for their absorption spectrum to be measured. In this study, we developed an optical-cavity-enhanced absorption spectroscopic microscopy method for two-dimensional absorption imaging. The light absorption is enhanced by an optical cavity system, which allows the detection of the absorption spectrum with samples having an optical path length as small as 10 μm, at a subcellular spatial resolution. Principal component analysis of various types of cultured mammalian cells indicates absorption-based cellular diversity. Interestingly, this diversity is observed among not only different species but also identical cell types. Furthermore, this microscopy technique allows us to observe frozen sections of tissue samples without any staining and is capable of label-free biopsy. Thus, our microscopy method opens the door for imaging the absorption spectra of biological samples and thereby detecting the individuality of cells. PMID:25950513

  13. Spectral fingerprinting of individual cells visualized by cavity-reflection-enhanced light-absorption microscopy.

    PubMed

    Arai, Yoshiyuki; Yamamoto, Takayuki; Minamikawa, Takeo; Takamatsu, Tetsuro; Nagai, Takeharu

    2015-01-01

    The absorption spectrum of light is known to be a "molecular fingerprint" that enables analysis of the molecular type and its amount. It would be useful to measure the absorption spectrum in single cell in order to investigate the cellular status. However, cells are too thin for their absorption spectrum to be measured. In this study, we developed an optical-cavity-enhanced absorption spectroscopic microscopy method for two-dimensional absorption imaging. The light absorption is enhanced by an optical cavity system, which allows the detection of the absorption spectrum with samples having an optical path length as small as 10 μm, at a subcellular spatial resolution. Principal component analysis of various types of cultured mammalian cells indicates absorption-based cellular diversity. Interestingly, this diversity is observed among not only different species but also identical cell types. Furthermore, this microscopy technique allows us to observe frozen sections of tissue samples without any staining and is capable of label-free biopsy. Thus, our microscopy method opens the door for imaging the absorption spectra of biological samples and thereby detecting the individuality of cells.

  14. Harrison-Zeldovich spectrum from conformal invariance

    SciTech Connect

    Rubakov, V.A.

    2009-09-01

    We show that flat spectrum of small perturbations of field(s) is generated in a simple way in a theory of multi-component scalar field provided this theory is conformally invariant, it has some global symmetry and the quartic potential is negative. We suggest a mechanism of converting these field perturbations into adiabatic scalar perturbations with flat spectrum.

  15. Autism spectrum disorder

    MedlinePlus

    Autism; Autistic disorder; Asperger syndrome; Childhood disintegrative disorder; Pervasive developmental disorder ... to better diagnosis and newer definitions of ASD. Autism spectrum disorder now includes syndromes that used to ...

  16. Ionospheric wave spectrum measurements

    NASA Technical Reports Server (NTRS)

    Harker, K. J.; Ilic, D. B.; Crawford, F. W.

    1979-01-01

    The local spectrum S(k, omega) of either potential or electron-density fluctuations can be used to determine macroscopic-plasma characteristics such as the local density and temperature, transport coefficients, and drift current. This local spectrum can be determined by measuring the cross-power spectrum. The paper examines the practicality of using the cross-power spectrum analyzer on the Space Shuttle to measure ionospheric parameters. Particular attention is given to investigating the integration time required to measure the cross-power spectral density to a desired accuracy.

  17. Laser plasma x-ray source for ultrafast time-resolved x-ray absorption spectroscopy.

    PubMed

    Miaja-Avila, L; O'Neil, G C; Uhlig, J; Cromer, C L; Dowell, M L; Jimenez, R; Hoover, A S; Silverman, K L; Ullom, J N

    2015-03-01

    We describe a laser-driven x-ray plasma source designed for ultrafast x-ray absorption spectroscopy. The source is comprised of a 1 kHz, 20 W, femtosecond pulsed infrared laser and a water target. We present the x-ray spectra as a function of laser energy and pulse duration. Additionally, we investigate the plasma temperature and photon flux as we vary the laser energy. We obtain a 75 μm FWHM x-ray spot size, containing ∼10(6) photons/s, by focusing the produced x-rays with a polycapillary optic. Since the acquisition of x-ray absorption spectra requires the averaging of measurements from >10(7) laser pulses, we also present data on the source stability, including single pulse measurements of the x-ray yield and the x-ray spectral shape. In single pulse measurements, the x-ray flux has a measured standard deviation of 8%, where the laser pointing is the main cause of variability. Further, we show that the variability in x-ray spectral shape from single pulses is low, thus justifying the combining of x-rays obtained from different laser pulses into a single spectrum. Finally, we show a static x-ray absorption spectrum of a ferrioxalate solution as detected by a microcalorimeter array. Altogether, our results demonstrate that this water-jet based plasma source is a suitable candidate for laboratory-based time-resolved x-ray absorption spectroscopy experiments. PMID:26798792

  18. Laser plasma x-ray source for ultrafast time-resolved x-ray absorption spectroscopy

    DOE PAGES

    Miaja-Avila, L.; O'Neil, G. C.; Uhlig, J.; Cromer, C. L.; Dowell, M. L.; Jimenez, R.; Hoover, A. S.; Silverman, K. L.; Ullom, J. N.

    2015-03-02

    We describe a laser-driven x-ray plasma source designed for ultrafast x-ray absorption spectroscopy. The source is comprised of a 1 kHz, 20 W, femtosecond pulsed infrared laser and a water target. We present the x-ray spectra as a function of laser energy and pulse duration. Additionally, we investigate the plasma temperature and photon flux as we vary the laser energy. We obtain a 75 μm FWHM x-ray spot size, containing ~106 photons/s, by focusing the produced x-rays with a polycapillary optic. Since the acquisition of x-ray absorption spectra requires the averaging of measurements from >107 laser pulses, we also presentmore » data on the source stability, including single pulse measurements of the x-ray yield and the x-ray spectral shape. In single pulse measurements, the x-ray flux has a measured standard deviation of 8%, where the laser pointing is the main cause of variability. Further, we show that the variability in x-ray spectral shape from single pulses is low, thus justifying the combining of x-rays obtained from different laser pulses into a single spectrum. Finally, we show a static x-ray absorption spectrum of a ferrioxalate solution as detected by a microcalorimeter array. Altogether, our results demonstrate that this water-jet based plasma source is a suitable candidate for laboratory-based time-resolved x-ray absorption spectroscopy experiments.« less

  19. Laser plasma x-ray source for ultrafast time-resolved x-ray absorption spectroscopy.

    PubMed

    Miaja-Avila, L; O'Neil, G C; Uhlig, J; Cromer, C L; Dowell, M L; Jimenez, R; Hoover, A S; Silverman, K L; Ullom, J N

    2015-03-01

    We describe a laser-driven x-ray plasma source designed for ultrafast x-ray absorption spectroscopy. The source is comprised of a 1 kHz, 20 W, femtosecond pulsed infrared laser and a water target. We present the x-ray spectra as a function of laser energy and pulse duration. Additionally, we investigate the plasma temperature and photon flux as we vary the laser energy. We obtain a 75 μm FWHM x-ray spot size, containing ∼10(6) photons/s, by focusing the produced x-rays with a polycapillary optic. Since the acquisition of x-ray absorption spectra requires the averaging of measurements from >10(7) laser pulses, we also present data on the source stability, including single pulse measurements of the x-ray yield and the x-ray spectral shape. In single pulse measurements, the x-ray flux has a measured standard deviation of 8%, where the laser pointing is the main cause of variability. Further, we show that the variability in x-ray spectral shape from single pulses is low, thus justifying the combining of x-rays obtained from different laser pulses into a single spectrum. Finally, we show a static x-ray absorption spectrum of a ferrioxalate solution as detected by a microcalorimeter array. Altogether, our results demonstrate that this water-jet based plasma source is a suitable candidate for laboratory-based time-resolved x-ray absorption spectroscopy experiments.

  20. Laser plasma x-ray source for ultrafast time-resolved x-ray absorption spectroscopy

    SciTech Connect

    Miaja-Avila, L.; O'Neil, G. C.; Uhlig, J.; Cromer, C. L.; Dowell, M. L.; Jimenez, R.; Hoover, A. S.; Silverman, K. L.; Ullom, J. N.

    2015-03-02

    We describe a laser-driven x-ray plasma source designed for ultrafast x-ray absorption spectroscopy. The source is comprised of a 1 kHz, 20 W, femtosecond pulsed infrared laser and a water target. We present the x-ray spectra as a function of laser energy and pulse duration. Additionally, we investigate the plasma temperature and photon flux as we vary the laser energy. We obtain a 75 μm FWHM x-ray spot size, containing ~106 photons/s, by focusing the produced x-rays with a polycapillary optic. Since the acquisition of x-ray absorption spectra requires the averaging of measurements from >107 laser pulses, we also present data on the source stability, including single pulse measurements of the x-ray yield and the x-ray spectral shape. In single pulse measurements, the x-ray flux has a measured standard deviation of 8%, where the laser pointing is the main cause of variability. Further, we show that the variability in x-ray spectral shape from single pulses is low, thus justifying the combining of x-rays obtained from different laser pulses into a single spectrum. Finally, we show a static x-ray absorption spectrum of a ferrioxalate solution as detected by a microcalorimeter array. Altogether, our results demonstrate that this water-jet based plasma source is a suitable candidate for laboratory-based time-resolved x-ray absorption spectroscopy experiments.

  1. Laser plasma x-ray source for ultrafast time-resolved x-ray absorption spectroscopy

    PubMed Central

    Miaja-Avila, L.; O'Neil, G. C.; Uhlig, J.; Cromer, C. L.; Dowell, M. L.; Jimenez, R.; Hoover, A. S.; Silverman, K. L.; Ullom, J. N.

    2015-01-01

    We describe a laser-driven x-ray plasma source designed for ultrafast x-ray absorption spectroscopy. The source is comprised of a 1 kHz, 20 W, femtosecond pulsed infrared laser and a water target. We present the x-ray spectra as a function of laser energy and pulse duration. Additionally, we investigate the plasma temperature and photon flux as we vary the laser energy. We obtain a 75 μm FWHM x-ray spot size, containing ∼106 photons/s, by focusing the produced x-rays with a polycapillary optic. Since the acquisition of x-ray absorption spectra requires the averaging of measurements from >107 laser pulses, we also present data on the source stability, including single pulse measurements of the x-ray yield and the x-ray spectral shape. In single pulse measurements, the x-ray flux has a measured standard deviation of 8%, where the laser pointing is the main cause of variability. Further, we show that the variability in x-ray spectral shape from single pulses is low, thus justifying the combining of x-rays obtained from different laser pulses into a single spectrum. Finally, we show a static x-ray absorption spectrum of a ferrioxalate solution as detected by a microcalorimeter array. Altogether, our results demonstrate that this water-jet based plasma source is a suitable candidate for laboratory-based time-resolved x-ray absorption spectroscopy experiments. PMID:26798792

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

    PubMed

    Taylor, Robert A; Phelan, Patrick E; Otanicar, Todd P; Adrian, Ronald; Prasher, Ravi

    2011-03-15

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

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

    PubMed Central

    2011-01-01

    Suspensions of nanoparticles (i.e., particles with diameters < 100 nm) in liquids, termed nanofluids, show remarkable thermal and optical property changes from the base liquid at low particle loadings. Recent studies also indicate that selected nanofluids may improve the efficiency of direct absorption solar thermal collectors. To determine the effectiveness of nanofluids in solar applications, their ability to convert light energy to thermal energy must be known. That is, their absorption of the solar spectrum must be established. Accordingly, this study compares model predictions to spectroscopic measurements of extinction coefficients over wavelengths that are important for solar energy (0.25 to 2.5 μm). A simple addition of the base fluid and nanoparticle extinction coefficients is applied as an approximation of the effective nanofluid extinction coefficient. Comparisons with measured extinction coefficients reveal that the approximation works well with water-based nanofluids containing graphite nanoparticles but less well with metallic nanoparticles and/or oil-based fluids. For the materials used in this study, over 95% of incoming sunlight can be absorbed (in a nanofluid thickness ≥10 cm) with extremely low nanoparticle volume fractions - less than 1 × 10-5, or 10 parts per million. Thus, nanofluids could be used to absorb sunlight with a negligible amount of viscosity and/or density (read: pumping power) increase. PMID:21711750

  4. [Research on the NO2 mean concentration measurement with target differential optical absorption spectroscopy technology].

    PubMed

    Liu, Jin; Si, Fu-Qi; Zhou, Hai-Jin; Zhao, Min-Jie; Dou, Ke; Liu, Wen-Qing

    2013-04-01

    A new monitoring method of NO2 concentration near ground with the target difference absorption spectrum technology (Target DOAS) is introduced in the present paper. This method is based on the passive difference absorption spectrum technology. The instrument collects solar reflection spectrum of remote objectives, such as wall of building and mountain, and a specific reference spectrum is chosen to subtract the influence of trace gases from the target to atmospheric top, then integrated concentration of NO2 along the path between the target and instrument can be calculated through the differential absorption spectra inversion algorithm. Since the distance between the instrument and target is given, the mean concentration of NO2 can be derived. With developed Target DOAS instrument, NO2 concentration measurement was carried out in Hefei. And comparison was made between the target DOAS and long path difference absorption spectrometer. Good consistency was presented, proving the feasibility of this method.

  5. [Research on the NO2 mean concentration measurement with target differential optical absorption spectroscopy technology].

    PubMed

    Liu, Jin; Si, Fu-Qi; Zhou, Hai-Jin; Zhao, Min-Jie; Dou, Ke; Liu, Wen-Qing

    2013-04-01

    A new monitoring method of NO2 concentration near ground with the target difference absorption spectrum technology (Target DOAS) is introduced in the present paper. This method is based on the passive difference absorption spectrum technology. The instrument collects solar reflection spectrum of remote objectives, such as wall of building and mountain, and a specific reference spectrum is chosen to subtract the influence of trace gases from the target to atmospheric top, then integrated concentration of NO2 along the path between the target and instrument can be calculated through the differential absorption spectra inversion algorithm. Since the distance between the instrument and target is given, the mean concentration of NO2 can be derived. With developed Target DOAS instrument, NO2 concentration measurement was carried out in Hefei. And comparison was made between the target DOAS and long path difference absorption spectrometer. Good consistency was presented, proving the feasibility of this method. PMID:23841393

  6. Compact characterization of liquid absorption and emission spectra using linear variable filters integrated with a CMOS imaging camera

    PubMed Central

    Wan, Yuhang; Carlson, John A.; Kesler, Benjamin A.; Peng, Wang; Su, Patrick; Al-Mulla, Saoud A.; Lim, Sung Jun; Smith, Andrew M.; Dallesasse, John M.; Cunningham, Brian T.

    2016-01-01

    A compact analysis platform for detecting liquid absorption and emission spectra using a set of optical linear variable filters atop a CMOS image sensor is presented. The working spectral range of the analysis platform can be extended without a reduction in spectral resolution by utilizing multiple linear variable filters with different wavelength ranges on the same CMOS sensor. With optical setup reconfiguration, its capability to measure both absorption and fluorescence emission is demonstrated. Quantitative detection of fluorescence emission down to 0.28 nM for quantum dot dispersions and 32 ng/mL for near-infrared dyes has been demonstrated on a single platform over a wide spectral range, as well as an absorption-based water quality test, showing the versatility of the system across liquid solutions for different emission and absorption bands. Comparison with a commercially available portable spectrometer and an optical spectrum analyzer shows our system has an improved signal-to-noise ratio and acceptable spectral resolution for discrimination of emission spectra, and characterization of colored liquid’s absorption characteristics generated by common biomolecular assays. This simple, compact, and versatile analysis platform demonstrates a path towards an integrated optical device that can be utilized for a wide variety of applications in point-of-use testing and point-of-care diagnostics. PMID:27389070

  7. Compact characterization of liquid absorption and emission spectra using linear variable filters integrated with a CMOS imaging camera.

    PubMed

    Wan, Yuhang; Carlson, John A; Kesler, Benjamin A; Peng, Wang; Su, Patrick; Al-Mulla, Saoud A; Lim, Sung Jun; Smith, Andrew M; Dallesasse, John M; Cunningham, Brian T

    2016-01-01

    A compact analysis platform for detecting liquid absorption and emission spectra using a set of optical linear variable filters atop a CMOS image sensor is presented. The working spectral range of the analysis platform can be extended without a reduction in spectral resolution by utilizing multiple linear variable filters with different wavelength ranges on the same CMOS sensor. With optical setup reconfiguration, its capability to measure both absorption and fluorescence emission is demonstrated. Quantitative detection of fluorescence emission down to 0.28 nM for quantum dot dispersions and 32 ng/mL for near-infrared dyes has been demonstrated on a single platform over a wide spectral range, as well as an absorption-based water quality test, showing the versatility of the system across liquid solutions for different emission and absorption bands. Comparison with a commercially available portable spectrometer and an optical spectrum analyzer shows our system has an improved signal-to-noise ratio and acceptable spectral resolution for discrimination of emission spectra, and characterization of colored liquid's absorption characteristics generated by common biomolecular assays. This simple, compact, and versatile analysis platform demonstrates a path towards an integrated optical device that can be utilized for a wide variety of applications in point-of-use testing and point-of-care diagnostics. PMID:27389070

  8. Compact characterization of liquid absorption and emission spectra using linear variable filters integrated with a CMOS imaging camera

    NASA Astrophysics Data System (ADS)

    Wan, Yuhang; Carlson, John A.; Kesler, Benjamin A.; Peng, Wang; Su, Patrick; Al-Mulla, Saoud A.; Lim, Sung Jun; Smith, Andrew M.; Dallesasse, John M.; Cunningham, Brian T.

    2016-07-01

    A compact analysis platform for detecting liquid absorption and emission spectra using a set of optical linear variable filters atop a CMOS image sensor is presented. The working spectral range of the analysis platform can be extended without a reduction in spectral resolution by utilizing multiple linear variable filters with different wavelength ranges on the same CMOS sensor. With optical setup reconfiguration, its capability to measure both absorption and fluorescence emission is demonstrated. Quantitative detection of fluorescence emission down to 0.28 nM for quantum dot dispersions and 32 ng/mL for near-infrared dyes has been demonstrated on a single platform over a wide spectral range, as well as an absorption-based water quality test, showing the versatility of the system across liquid solutions for different emission and absorption bands. Comparison with a commercially available portable spectrometer and an optical spectrum analyzer shows our system has an improved signal-to-noise ratio and acceptable spectral resolution for discrimination of emission spectra, and characterization of colored liquid’s absorption characteristics generated by common biomolecular assays. This simple, compact, and versatile analysis platform demonstrates a path towards an integrated optical device that can be utilized for a wide variety of applications in point-of-use testing and point-of-care diagnostics.

  9. The application of reduced absorption cross section on the identification of the compounds with similar function-groups

    NASA Astrophysics Data System (ADS)

    Yu, Fei; Zuo, Jian; Mu, Kai-jun; Zhang, Zhen-wei; Zhang, Liang-liang; Zhang, Lei-wei; Zhang, Cun-lin

    2013-08-01

    Terahertz spectroscopy is a powerful tool for materials investigation. The low frequency vibrations were usually investigated by means of absorption coefficient regardless of the refractive index. It leads to the disregard of some inherent low-frequency vibrational information of the chemical compounds. Moreover, due to the scattering inside the sample, there are some distortions of the absorption features, so that the absorption dependent material identification is not valid enough. Here, a statistical parameter named reduced absorption cross section (RACS) is introduced. This can not only help us investigate the molecular dynamics but also distinguish one chemical compound with another which has similar function-groups. Experiments are carried out on L-Tyrosine and L-Phenylalanine and the different mass ratios of their mixtures as an example of the application of RACS. The results come out that the RACS spectrum of L-Tyrosine and L-Phenylalanine reserve the spectral fingerprint information of absorption spectrum. The log plot of RACSs of the two amino acids show power-law behavior σR(~ν) ~ (ν~α), and there is a linear relation between the wavenumber and the RACS in the double logarithmic plot. The exponents α, at the same time, are the slopes of the RACS curves in the double logarithmic plot. The big differences of the exponents α between the two amino acids and their mixtures can be seen visually from the slopes of the RACS curves. So we can use RACS analytical method to distinguish some complex compounds with similar function-groups and mixtures from another which has similar absorption peaks in THz region.

  10. The BUSS spectrum of Beta Lyrae. [Balloon-borne Ultraviolet Stellar Spectrograph

    NASA Technical Reports Server (NTRS)

    Hack, M.; Sahade, J.; De Jager, C.; Kondo, Y.

    1983-01-01

    The spectrum of Beta Lyrae from about 1975 to 3010 A taken with the Balloon-borne ultraviolet Stellar Spectrograph experiment in May 1976 at phase 0.61 P is analyzed. Results show the presence of N II semi-forbidden emission and provide evidence for about the same location, in the outer envelope of the system, of the layers responsible for the resonance Mg II doublet emissions and for the "narrow" H-alpha emission. In addition, three sets of absorption lines, P Cygni profiles of Fe III and broad Beals Type III emissions of Mg II, are found to be present.

  11. Absorption by ground-state lead atoms of the 283. 3-nm resonant line from a lead hollow cathode lamp. An absolute number density calibration

    SciTech Connect

    Simons, J.W. ); Oldenborg, R.C.; Baughcum, S.L. )

    1989-10-19

    An accurate absolute number density calibration curve for absorption by gaseous lead atoms of the 283.3-nm resonant line from a typical lead hollow cathode lamp is reported. This calibration shows the usual curvature in the Beer-Lambert plot for atomic absorption at moderate to high absorbances that is commonly attributed to self-absorption leading to line reversal in the source and/or preferential absorption at the line center when the absorber temperature is not much greater than the source Doppler temperature. A theoretical calculation utilizing a Doppler-limited Fourier transform spectrum of the 283.3-nm emission from the lamp and a tabulated value of the absorption cross section and accounting for the isotopic and nuclear hyperfine components in both the emission and absorption due to naturally occurring lead quantitatively reproduces the experimental calibration curve without any parameter adjustments. It is found that the curvature in the Beer-Lambert plot has more to do with the fact that the absorbing and emitting atoms are a mixture of isotopes giving several isotopic and nuclear hyperfine transitions at slightly different frequencies than it does with preferential absorption at line centers.

  12. Measurements of the absorption line strength of hydroperoxyl radical in the ν3 band using a continuous wave quantum cascade laser.

    PubMed

    Sakamoto, Yosuke; Tonokura, Kenichi

    2012-01-12

    Mid-infrared absorption spectroscopy has been applied to the detection of the hydroperoxyl (HO(2)) radical in pulsed laser photolysis combined with a laser absorption kinetics reactor. Transitions of the ν(3) vibrational band assigned to the O-O stretch mode were probed with a thermoelectrically cooled, continuous wave mid-infrared distributed feedback quantum cascade laser (QCL). The HO(2) radicals were generated with the photolysis of Cl(2)/CH(3)OH/O(2) mixtures at 355 nm. The absorption cross section at each pressure was determined by three methods at 1065.203 cm(-1) for the F(1), 13(1,13) ← 14(1,14) transition in the ν(3) band. From these values, the absolute absorption cross section at zero pressure was estimated. The relative line strengths of other absorptions in the feasible emitting frequency range of the QCL from 1061.17 to 1065.28 cm(-1) were also measured, and agreed with values reproduced from the HITRAN database. The ν(3) band absorption strength was estimated from the analytically obtained absolute absorption cross section and the calculated relative intensity by spectrum simulation, to be 21.4 ± 4.2 km mol(-1), which shows an agreement with results of quantum chemical calculations. PMID:22148191

  13. Measurements of the absorption line strength of hydroperoxyl radical in the ν3 band using a continuous wave quantum cascade laser.

    PubMed

    Sakamoto, Yosuke; Tonokura, Kenichi

    2012-01-12

    Mid-infrared absorption spectroscopy has been applied to the detection of the hydroperoxyl (HO(2)) radical in pulsed laser photolysis combined with a laser absorption kinetics reactor. Transitions of the ν(3) vibrational band assigned to the O-O stretch mode were probed with a thermoelectrically cooled, continuous wave mid-infrared distributed feedback quantum cascade laser (QCL). The HO(2) radicals were generated with the photolysis of Cl(2)/CH(3)OH/O(2) mixtures at 355 nm. The absorption cross section at each pressure was determined by three methods at 1065.203 cm(-1) for the F(1), 13(1,13) ← 14(1,14) transition in the ν(3) band. From these values, the absolute absorption cross section at zero pressure was estimated. The relative line strengths of other absorptions in the feasible emitting frequency range of the QCL from 1061.17 to 1065.28 cm(-1) were also measured, and agreed with values reproduced from the HITRAN database. The ν(3) band absorption strength was estimated from the analytically obtained absolute absorption cross section and the calculated relative intensity by spectrum simulation, to be 21.4 ± 4.2 km mol(-1), which shows an agreement with results of quantum chemical calculations.

  14. 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.

  15. 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.

  16. Renormalization Group Approach to the X-Ray Absorption Problem and Application to the Vigman-Finkelshtein Model for Magnetic Impurities in Metals.

    NASA Astrophysics Data System (ADS)

    Nunes de Oliveira, Luiz

    energy. The absorption spectrum approaches a power law in the energy range (omega)-(omega)(,T) >> (GAMMA), where (GAMMA) is the width of the resonant level, and a different power law in the range (omega)-(omega)(,T) << (GAMMA). Qualitative arguments determining the exponents describing the two power laws are presented. In the intermediate energy range, (omega)-(omega)(,T) (TURNEQ) (GAMMA), the numerical results show that, under appropriate circumstances, an antiresonance, i.e., a zero in the absorption spectrum, will appear. The relation between this effect and the Fano antiresonance (a single-body effect found in the spectrum of certain systems having a discrete level coupled to a continuum of energies) is elaborated. The problem of the specific heat of dilute magnetic alloys is attacked by analyzing the Vigman-Finkelshtein model, a recently proposed model for magnetic impurities in metals. With the aid of results from the x-ray problem, a mapping between this spinless model and the Kondo model for magnetic impurities in metals is established. It is shown that the parameters in the Vigman-Finkelshtein model can be chosen so that, for all temperatures k(,B)T << D, the susceptibility for the Vigman-Finkelshtein model agrees within the accuracy of the numerical calculation with Wilson's results for the susceptibility in the Kondo model. The specific heat for the Vigman-Finkelshtein model is calculated as a function of temperature; the mapping to the Kondo model shows that the resulting curve gives a quantitative description of the specific heat for the Kondo model, whereas a numerical calculation in that model would require a thousandfold increase in computational cost.

  17. Interpretation of the absorption and circular dichroic spectra of oriented purple membrane films.

    PubMed Central

    Muccio, D D; Cassim, J Y

    1979-01-01

    The absorption and circular dichroic (CD) spectra of purple membrane films in which the plane of the membranes is oriented perpendicular to the incident beam are compared with the solution spectra. This enables one to relate structural features of the purple membrane to a coordinate system as defined by a normal to the membrane plane and two mutually perpendicular in-plane axes. The film and solution absorption spectra were similar except for a relative depression in the 200 - 225-nm region of the film spectrum. However, the CD spectra showed significant differences in the visible region, where the biphasic band in the solution spectrum was replaced by a single positive band at 555 nm in the film spectrum and in the far ultraviolet region, where the 208-nm band was deleted from the film spectra of the native and regenerated membranes. Moreover, a small shoulder occurred at 208 nm in the film spectrum of the bleached membrane. The near ultraviolet spectra also showed differences, whereas the 317-nm band remained essentially the same for both spectra. Based on excitonic interpretations of the visible and far ultraviolet spectra the following conclusions were reached: (a) a relatively strong in-plane monomeric interaction occurs between te retinyl chromophore and apoprotein; (b) the helical axes of the native and regenerated membrane proteins are oriented primarily normal to the membrane plane; and (c) the helical axes of the bleached membrane proteins are tilted more in-plane than the axes of the native or regenerated membrane. Additional conclusions were that an interaction occurs between an in-plane magnetic dipole moment of the retinyl chromophore and probably an in-plane electric dipole moment of a nearby aromatic amino acid(s), and that although the membrane is anisotropic with respect to coupling between electric and magnetic moments of the aromatic amino acids, the transition dipole moments of the aromatic amino acids are not preferentially oriented in either

  18. Absorption of planar waves in a draining bathtub

    SciTech Connect

    Oliveira, Ednilton S.; Dolan, Sam R.; Crispino, Luis C. B.

    2010-06-15

    We present an analysis of the absorption of acoustic waves by a black hole analogue in (2+1) dimensions generated by a fluid flow in a draining bathtub. We show that the low-frequency absorption length is equal to the acoustic hole circumference and that the high-frequency absorption length is 4 times the ergoregion radius. For intermediate values of the wave frequency, we compute the absorption length numerically and show that our results are in excellent agreement with the low- and high-frequency limits. We analyze the occurrence of superradiance, manifested as negative partial absorption lengths for corotating modes at low frequencies.

  19. An investigation of a mathematical model for atmospheric absorption spectra

    NASA Technical Reports Server (NTRS)

    Niple, E. R.

    1979-01-01

    A computer program that calculates absorption spectra for slant paths through the atmosphere is described. The program uses an efficient convolution technique (Romberg integration) to simulate instrument resolution effects. A brief information analysis is performed on a set of calculated spectra to illustrate how such techniques may be used to explore the quality of the information in a spectrum.

  20. Absorption mapping for characterization of glass surfaces.

    PubMed

    Commandré, M; Roche, P; Borgogno, J P; Albrand, G

    1995-05-01

    The surface quality of bare substrates and preparation procedures take on an important role in optical coating performances. The most commonly used techniques of characterization generally give information about roughness and local defects. A photothermal deflection technique is used for mapping surface absorption of fused-silica and glass substrates. We show that absorption mapping gives specific information on surface contamination of bare substrates. We present experimental results concerning substrates prepared by different cleaning and polishing techniques. We show that highly polished surfaces lead to the lowest values of residual surface absorption. Moreover the cleaning behavior of surfaces of multicomponent glasses and their optical performance in terms of absorption are proved to be different from those of fused silica.

  1. Origins of Absorption Systems of Classical Nova V2659 Cyg (Nova Cyg 2014)

    NASA Astrophysics Data System (ADS)

    Arai, A.; Kawakita, H.; Shinnaka, Y.; Tajitsu, A.

    2016-10-01

    We report on high-dispersion spectroscopy results of a classical nova V2659 Cyg (Nova Cyg 2014) that are taken 33.05 days after the V-band maximum. The spectrum shows two distinct blueshifted absorption systems originating from H i, Fe ii, Ca ii, etc. The radial velocities of the absorption systems are ‑620 km s‑1, and ‑1100 to ‑1500 km s‑1. The higher velocity component corresponds to the P-Cygni absorption features frequently observed in low-resolution spectra. Much larger numbers of absorption lines are identified at the lower velocity. These mainly originate from neutral or singly ionized Fe-peak elements (Fe i, Ti ii, Cr ii, etc.). Based on the results of our spectroscopic observations, we discuss the structure of the ejecta of V2659 Cyg. We conclude that the low- and high-velocity components are likely to be produced by the outflow wind and the ballistic nova ejecta, respectively.

  2. Measurement of Broad Absorption Features Using a Tunable External Cavity Quantum Cascade Laser

    SciTech Connect

    Phillips, Mark C.; Myers, Tanya L.; Wojcik, Michael D.; Cannon, Bret D.; Taubman, Matthew S.; Scott, David C.

    2007-09-25

    We demonstrate the use of a tunable external cavity quantum cascade laser system for measurement of broad absorption features in the mid-infrared spectral region. The thermoelectrically cooled external cavity laser was tuned over a 65 cm-1 range centered at 8.7 microns using stepper motor control. Pulsing the laser at a high duty cycle provided 3-5 mW average output power over the tuning range, and enabled phase-sensitive detection of amplitude-modulated signals. We used the laser system to measure the absorption spectra of Freon-125 using a Herriott cell. In addition, the absorption spectrum of water in the laboratory air was measured. The measurements showed excellent agreement with reference spectra, in both wavelength and amplitude. The measured scan resolution of 0.14 cm-1 is suitable for measurement of the absorption features of complex molecules as well as simple molecules with atmospherically broadened lines. We discuss the limits to the scan resolution due to effects of spectral chirp and mode-hops during pulsed operation.

  3. Retrieval of Black Carbon Absorption from Proposed Satellite Measurements Over the Ocean Glint

    NASA Technical Reports Server (NTRS)

    Kaufman, Y. J.; Matins, J. V.; Remer, L. A.; Schoeberl, M. R.; Yamasoe, M. A.; Lau, William K. M. (Technical Monitor)

    2001-01-01

    Haze and air pollution includes many chemicals that together form small particles suspended in the air called aerosols. One of the main ingredients found to affect climate and human health is Black Carbon. Black particles emitted from engines that do not burn the fuel completely, e.g. old trucks. Black carbon absorption of sunlight emerges as one of the key components of man-made forcing of climate. However, global characterization of black carbon emissions, distribution and pathways in which it can affect the amount of solar radiation absorbed by the atmosphere is very uncertain. A new method is proposed to measure sunlight absorption by fine aerosol particles containing black carbon over the ocean glint from a satellite mission designed for this purpose. The satellite will scan the same spot over the ocean in the glint plane and a plane 40 degrees off-glint a minute apart, collecting measurements of the reflected light across the solar spectrum. First the dark ocean off the glint is used to derive aerosol properties. Then the black carbon absorption is derived prop the attenuation of the bright glint by the aerosol layer. Such measurements if realized in a proposed future mission - COBRA are expected to produce global monthly climatology of black carbon absorption with high accuracy (110 to 15%) that can show their effect on climate.

  4. Measurement of broad absorption features using a tunable external cavity quantum cascade laser

    NASA Astrophysics Data System (ADS)

    Phillips, Mark C.; Myers, Tanya L.; Wojcik, Michael D.; Cannon, Bret D.; Taubman, Matthew S.; Scott, David C.

    2007-09-01

    We demonstrate the use of a tunable external cavity quantum cascade laser system for measurement of broad absorption features in the mid-infrared spectral region. The thermoelectrically cooled external cavity laser was tuned over a 65 cm -1range centered at 8.7 microns using stepper motor control. Pulsing the laser at a high duty cycle provided 2-4.5 mW average output power over the tuning range, and enabled phase-sensitive detection of amplitude-modulated signals. We used the laser system to measure the absorption spectra of Freon-125 using a Herriott cell. In addition, the absorption spectrum of water in the laboratory air was measured. The measurements showed excellent agreement with reference spectra, in both wavelength and amplitude. The measured scan resolution of 0.14 cm -1 is suitable for measurement of the absorption features of complex molecules as well as simple molecules with atmospherically broadened lines. We discuss the limits to the scan resolution due to effects of spectral chirp and mode-hops during pulsed operation.

  5. Visible absorption properties of radiation exposed XR type-T radiochromic film.

    PubMed

    Butson, Martin J; Cheung, Tsang; Yu, Peter K N

    2004-10-01

    The visible absorption spectra of Gafchromic XR type-T radiochromic film have been investigated to analyse the dosimetry characteristics of the film with visible light densitometers. Common densitometers can use photospectrometry, fluorescent light (broad-band visible), helium neon (632 nm), light emitting diode (LED) or other specific bandwidth spectra. The visible absorption spectra of this film when exposed to photon radiation show peaks at 676 nm and 618 nm at 2 Gy absorbed doses which shift to slightly lower wavelengths (662 nm and 612 nm at 8 Gy absorbed dose) at higher doses. This is similar to previous models of Gafchromic film such as MD-55-2 and HS but XR type-T also includes a large absorption at lower visible wavelengths due to 'yellow' dyes placed within the film to aid with visible recognition of the film exposure level. The yellow dye band pass is produced at approximately 520 nm to 550 nm and absorbs wavelengths lower than this value within the visible spectrum. This accounts for the colour change from yellow to brown through the added absorption in the red wavelengths with radiation exposure. The film produces a relatively high dose sensitivity with up to 0.25 OD units per Gy change at 672 nm at 100 kVp x-ray energy. Variations in dose sensitivity can be achieved by varying wavelength analysis.

  6. Spectrophotometry of six broad absorption line QSOs

    NASA Technical Reports Server (NTRS)

    Junkkarinen, Vesa T.; Burbidge, E. Margaret; Smith, Harding E.

    1987-01-01

    Spectrophotometric observations of six broad absorption-line QSOs (BALQSOs) are presented. The continua and emission lines are compared with those in the spectra of QSOs without BALs. A statistically significant difference is found in the emission-line intensity ratio for (N V 1240-A)/(C IV 1549-A). The median value of (N V)/(C IV) for the BALQSOs is two to three times the median for QSOs without BALs. The absorption features of the BALQSOs are described, and the column densities and limits on the ionization structure of the BAL region are discussed. If the dominant ionization mechanism is photoionization, then it is likely that either the ionizing spectrum is steep or the abundances are considerably different from solar. Collisional ionization may be a significant factor, but it cannot totally dominate the ionization rate.

  7. Identification of Gas Phase PAHs in Absorption Towards Protostellar Sources

    NASA Technical Reports Server (NTRS)

    Bregman, Jesse D.; Temi, Pasquale; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    The infrared emission bands (also known as the UIR bands.) have recently been observed in absorption at 3.25 micrometers in the ices surrounding a few proto-stellar objects at 11.2 micrometers in MonR2, and at 6.2 micrometers towards two sources near the galactic center. The UIR bands have been observed in emission for many years, but identifying these bands has proven to be both difficult and contentious as no one has yet found a single material that provides a good match to the features. However, most investigators agree that some form of carbon-based material with aromatic bonds is the most likely candidate, and many arguments favor free molecules (polycyclic aromatic hydrocarbons, PAHs) as the carriers of at least the narrow emission bands. Since the emission arises not from a single molecule but from a family of molecules, identifying which PAHs are contributing to the infrared emission bands is difficult. The identification is further complicated by the fact that the emission at short wavelengths is dominated by small molecules while at long wavelengths it is dominated by large molecules. Thus, for example, the emission at 3.3 micrometers is from a different mix of molecules than those which produce the 11.2 micrometer band. To complicate matters further, the molecular mix includes both neutral and ionic species. In absorption, the same mixture of molecules contributes at all wavelengths and the molecules should be neutral, potentially simplifying comparisons with lab data. Also, absorption strengths measured in the lab are directly applicable to interstellar absorption bands without the need to model an emission spectrum of an unknown mixture of ionized and neutral PAHs. In this paper we show that a mixture of argon matrix isolated PAH molecules can reproduce the 3.25 micrometers absorption band seen in the ISO SWS spectra of four embedded Infrared sources, S140 IRS1, AFGL 2591, Elias 29, and AFGL 989. In section 2 we describe the ISO SWS data analysis and

  8. Fission Spectrum Related Uncertainties

    SciTech Connect

    G. Aliberti; I. Kodeli; G. Palmiotti; M. Salvatores

    2007-10-01

    The paper presents a preliminary uncertainty analysis related to potential uncertainties on the fission spectrum data. Consistent results are shown for a reference fast reactor design configuration and for experimental thermal configurations. However the results obtained indicate the need for further analysis, in particular in terms of fission spectrum uncertainty data assessment.

  9. Radiation detector spectrum simulator

    DOEpatents

    Wolf, Michael A.; Crowell, John M.

    1987-01-01

    A small battery operated nuclear spectrum simulator having a noise source nerates pulses with a Gaussian distribution of amplitudes. A switched dc bias circuit cooperating therewith generates several nominal amplitudes of such pulses and a spectral distribution of pulses that closely simulates the spectrum produced by a radiation source such as Americium 241.

  10. Radiation detector spectrum simulator

    DOEpatents

    Wolf, M.A.; Crowell, J.M.

    1985-04-09

    A small battery operated nuclear spectrum simulator having a noise source generates pulses with a Gaussian distribution of amplitudes. A switched dc bias circuit cooperating therewith to generate several nominal amplitudes of such pulses and a spectral distribution of pulses that closely simulates the spectrum produced by a radiation source such as Americium 241.

  11. Fetal Alcohol Spectrum Disorder

    ERIC Educational Resources Information Center

    Caley, Linda M.; Kramer, Charlotte; Robinson, Luther K.

    2005-01-01

    Fetal alcohol spectrum disorder (FASD) is a serious and widespread problem in this country. Positioned within the community with links to children, families, and healthcare systems, school nurses are a critical element in the prevention and treatment of those affected by fetal alcohol spectrum disorder. Although most school nurses are familiar…

  12. The CMBR spectrum

    SciTech Connect

    Stebbins, A.

    1997-05-01

    Here we give an introduction to the observed spectrum of the Cosmic Microwave Background Radiation (CMBR) and discuss what can be learned about it. Particular attention will be given to how Compton scattering can distort the spectrum of the CMBR. An incomplete bibliography of relevant papers is also provided.

  13. Enhanced absorption in silicon metamaterials waveguide structure

    NASA Astrophysics Data System (ADS)

    Hamouche, Houria; Shabat, Mohammed M.

    2016-07-01

    Metamaterial waveguide structures for silicon solar cells are a novel approach to antireflection coating structures that can be used for the achievement of high absorption in silicon solar cells. This paper investigates numerically the possibility of improving the performance of a planar waveguide silicon solar cell by incorporating a pair of silicon nitride/metamaterial layer between a semi-infinite glass cover layer and a semi-infinite silicon substrate layer. The optimized layer thicknesses of the pair are determined under the solar spectrum AM1.5 by the effective average reflectance method. The transmission and reflection coefficients are derived by the transfer matrix method for values of metamaterial's refractive index in visible and near-infrared radiation. In addition, the absorption coefficient is examined for several angles of incidence of the transverse electric polarized (TE), transverse magnetic polarized (TM) and the total (TE&TM) guided waves. Numerical results provide an extremely high absorption. The absorptivity of the structure achieves greater than 98 %.

  14. A Synthesis of Light Absorption Properties of the Arctic Ocean: Application to Semi-analytical Estimates of Dissolved Organic Carbon Concentrations from Space

    NASA Technical Reports Server (NTRS)

    Matsuoka, A.; Babin, M.; Doxaran, D.; Hooker, S. B.; Mitchell, B. G.; Belanger, S.; Bricaud, A.

    2014-01-01

    The light absorption coefficients of particulate and dissolved materials are the main factors determining the light propagation of the visible part of the spectrum and are, thus, important for developing ocean color algorithms. While these absorption properties have recently been documented by a few studies for the Arctic Ocean [e.g., Matsuoka et al., 2007, 2011; Ben Mustapha et al., 2012], the datasets used in the literature were sparse and individually insufficient to draw a general view of the basin-wide spatial and temporal variations in absorption. To achieve such a task, we built a large absorption database at the pan-Arctic scale by pooling the majority of published datasets and merging new datasets. Our results showed that the total non-water absorption coefficients measured in the Eastern Arctic Ocean (EAO; Siberian side) are significantly higher 74 than in the Western Arctic Ocean (WAO; North American side). This higher absorption is explained 75 by higher concentration of colored dissolved organic matter (CDOM) in watersheds on the Siberian 76 side, which contains a large amount of dissolved organic carbon (DOC) compared to waters off 77 North America. In contrast, the relationship between the phytoplankton absorption (a()) and chlorophyll a (chl a) concentration in the EAO was not significantly different from that in the WAO. Because our semi-analytical CDOM absorption algorithm is based on chl a-specific a() values [Matsuoka et al., 2013], this result indirectly suggests that CDOM absorption can be appropriately erived not only for the WAO but also for the EAO using ocean color data. Derived CDOM absorption values were reasonable compared to in situ measurements. By combining this algorithm with empirical DOC versus CDOM relationships, a semi-analytical algorithm for estimating DOC concentrations for coastal waters at the Pan-Arctic scale is presented and applied to satellite ocean color data.

  15. CO2 laser light absorption characteristics of metal powders

    NASA Astrophysics Data System (ADS)

    Haag, M.; Hügel, H.; Albright, C. E.; Ramasamy, S.

    1996-04-01

    Absorption characteristics of metal powders for 10.6 μm CO2 laser radiation were examined. Using a calorimetric method, absorptance measurements were performed on four different powder materials, including aluminum, copper, iron, and titanium aluminide. The experimental results showed that laser absorptance depends on powder porosity and material. The measured absorptance values at low laser intensities ranged between 28% and 43%. The titanium aluminide powders showed the highest absorptance values, and aluminum powders the lowest. As laser intensity was increased, the copper and iron powders showed strong signs of oxidation when irradiated in air, resulting in an increase in absorptance. Neither oxidation nor increased absorptance were observed when helium or argon were used as shielding gas.

  16. Polarization control of intermediate state absorption in resonance-mediated multi-photon absorption process

    NASA Astrophysics Data System (ADS)

    Xu, Shuwu; Huang, Yunxia; Yao, Yunhua; Jia, Tianqing; Ding, Jingxin; Zhang, Shian; Sun, Zhenrong

    2015-07-01

    We theoretically and experimentally demonstrate the control of the intermediate state absorption in an (n + m) resonance-mediated multi-photon absorption process by the polarization-modulated femtosecond laser pulse. An analytical solution of the intermediate state absorption in a resonance-mediated multi-photon absorption process is obtained based on the time-dependent perturbation theory. Our theoretical results show that the control efficiency of the intermediate state absorption by the polarization modulation is independent of the laser intensity when the transition from the intermediate state to the final state is coupled by the single-photon absorption, but will be affected by the laser intensity when this transition is coupled by the non-resonant multi-photon absorption. These theoretical results are experimentally confirmed via a two-photon fluorescence control in (2 + 1) resonance-mediated three-photon absorption of Coumarin 480 dye and a single-photon fluorescence control in (1 + 2) resonance-mediated three-photon absorption of IR 125 dye.

  17. Absorption spectra and photolysis of methyl peroxide in liquid and frozen water.

    PubMed

    Epstein, Scott A; Shemesh, Dorit; Tran, Van T; Nizkorodov, Sergey A; Gerber, R Benny

    2012-06-21

    Methyl peroxide (CH(3)OOH) is commonly found in atmospheric waters and ices in significant concentrations. It is the simplest organic peroxide and an important precursor to hydroxyl radical. Many studies have examined the photochemical behavior of gaseous CH(3)OOH; however, the photochemistry of liquid and frozen water solutions is poorly understood. We present a series of experiments and theoretical calculations designed to elucidate the photochemical behavior of CH(3)OOH dissolved in liquid water and ice over a range of temperatures. The molar extinction coefficients of aqueous CH(3)OOH are different from the gas phase, and they do not change upon freezing. Between -12 and 43 °C, the quantum yield of CH(3)OOH photolysis is described by the following equation: Φ(T) = exp((-2175 ± 448)1/T) + 7.66 ± 1.56). We use on-the-fly ab initio molecular dynamics simulations to model structures and absorption spectra of a bare CH(3)OOH molecule and a CH(3)OOH molecule immersed inside 20 water molecules at 50, 200, and 220 K. The simulations predict large sensitivity in the absorption spectrum of CH(3)OOH to temperature, with the spectrum narrowing and shifting to the blue under cryogenic conditions because of constrained dihedral motion around the O-O bond. The shift in the absorption spectrum is not observed in the experiment when the CH(3)OOH solution is frozen suggesting that CH(3)OOH remains in a liquid layer between the ice grains. Using the extinction coefficients and photolysis quantum yields obtained in this work, we show that under conditions with low temperatures, in the presence of clouds with a high liquid-water content and large solar zenith angles, the loss of CH(3)OOH by aqueous photolysis is responsible for up to 20% of the total loss of CH(3)OOH due to photolysis. Gas phase photolysis of CH(3)OOH dominates under all other conditions.

  18. 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.

  19. The role of deuterium in optical activity: The CD spectrum of (S,S)-dideuteriooxirane

    SciTech Connect

    Ben-Tzur, S.; Basil, A.; Gedanken, A.

    1992-07-01

    The circular dichroism of (S,S)-[2,3-{sup 2}H{sub 2}]oxirane has been investigated in the gas phase over the 1800-1500-{angstrom} region. While the absorption spectrum reveals only two allowed transitions, the circular dichroism (CD) spectrum shows a third transition which is magnetic dipole allowed and electric dipole forbidden. The CD sign of the first excited state complies with a quadrant rule which was formulated for the oxirane chromophore. This consignate behavior is contrary to the role of deuterium in carbonyl compounds, where an antioctant behavior is observed. The signs of the CD signals of the first excited state for oxiranes with methyl or deuterium substituents located in the same quadrant are the same, in contrast to the antioctant behavior of deuterium in carbonyls. This leaves the chirality rule formulated for substituted oxiranes without any exceptions. 33 refs., 1 fig.

  20. Changes in the ultraviolet spectrum of the mass-losing Be star 59 Cygni

    NASA Technical Reports Server (NTRS)

    Marlborough, J. M.; Snow, T. P., Jr.

    1980-01-01

    Observations of a few selected wavelength regions in the ultraviolet spectrum of the Be star 59 Cyg, obtained in 1975 November, are compared with the complete low-resolution Copernicus scan of the same star obtained in 1972 October. Changes in the spectrum between the two times are discussed and interpreted in terms of the two distinct shell episodes revealed by optical data. A wide range of ionization exists from Fe III to N V, with a range in radial velocity of approximately 1000 km/s. Changes in the Si III, Si IV, and N V absorption arising in the stellar wind show that the velocity structure of the wind may have changed, and that the ionization balance also was altered over the 3 year interim.