WorldWideScience

Sample records for absorption line spectra

  1. Identification of Metal Absorption Lines on Quasar Spectra of SDSS ...

    Indian Academy of Sciences (India)

    Key words. Line: identification—quasars: absorption lines—quasars: general. 1. Motivation. Absorption lines are often observed on the quasar spectrum. The intrinsic absorption lines of quasars are often thought to originate in the ionized gas that are physically related with the corresponding quasars, while the intervening ...

  2. Identification of Metal Absorption Lines on Quasar Spectra of SDSS ...

    Indian Academy of Sciences (India)

    . Baise 533000, China. 2Guangdong University of Technology, Guangzhou 510006, China. 3Centre for Astrophysics, Guangzhou University, Guangzhou 510006, China. ∗ e-mail: cysu@gdut.edu.cn. Abstract. Absorption lines are an important ...

  3. Monitoring the variability of intrinsic absorption lines in quasar spectra , ,

    Energy Technology Data Exchange (ETDEWEB)

    Misawa, Toru [School of General Education, Shinshu University, 3-1-1 Asahi, Matsumoto, Nagano 390-8621 (Japan); Charlton, Jane C.; Eracleous, Michael, E-mail: misawatr@shinshu-u.ac.jp [Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States)

    2014-09-01

    We have monitored 12 intrinsic narrow absorption lines (NALs) in five quasars and seven mini-broad absorption lines (mini-BALs) in six quasars for a period of 4-12 yr (1-3.5 yr in the quasar rest-frame). We present the observational data and the conclusions that follow immediately from them, as a prelude to a more detailed analysis. We found clear variability in the equivalent widths (EWs) of the mini-BAL systems but no easily discernible changes in their profiles. We did not detect any variability in the NAL systems or in narrow components that are often located at the center of mini-BAL profiles. Variations in mini-BAL EWs are larger at longer time intervals, reminiscent of the trend seen in variable BALs. If we assume that the observed variations result from changes in the ionization state of the mini-BAL gas, we infer lower limits to the gas density ∼10{sup 3}-10{sup 5} cm{sup –3} and upper limits on the distance of the absorbers from the central engine of the order of a few kiloparsecs. Motivated by the observed variability properties, we suggest that mini-BALs can vary because of fluctuations of the ionizing continuum or changes in partial coverage while NALs can vary primarily because of changes in partial coverage.

  4. Radiatively driven winds for different power law spectra. [for explaining narrow and broad quasar absorption lines

    Science.gov (United States)

    Beltrametti, M.

    1980-01-01

    The analytic solutions for radiatively driven winds are given for the case in which the winds are driven by absorption of line and continuum radiation. The wind solutions are analytically estimated for different parameters of the central source and for different power law spectra. For flat spectra, three sonic points can exist; it is shown, however, that only one of these sonic points is physically realistic. Parameters of the central source are given which generate winds of further interest for explaining the narrow and broad absorption lines in quasars. For the quasar model presented here, winds which could give rise to the narrow absorption lines are generated by central sources with parameters which are not realistic for quasars.

  5. VizieR Online Data Catalog: Sgr B2 los molecular absorption line spectra (Corby+, 2018)

    Science.gov (United States)

    Corby, J. F.; McGuire, B. A.; Herbst, E.; Remijan, A. J.

    2017-11-01

    Spectra covering transitions of c-C3H2, c-H1 SO, CCS, H2CS, HCS+, OH, SiO, 29SiO, H2CO, H2(13C)O, l-C3H, and l-C3H+ with line-of-sight absorption observed in the 1-50 GHz data from the PRebiotic Interstellar MOlecular Survey (PRIMOS) taken with the Robert C. Byrd Green Bank Telescope (GBT). Data were observed between 2001 and 2014, with the majority of the data obtained in 2007 in GBT Key Science project ID GBT07A-051. Spectra have been baseline-subtracted using best fit polynomials as described in the paper, and normalized by the continuum, so that the y-axis represents (T/TC-1). Data are provided in the FITS format; each FITS file contains all lines of a single molecule that are observed to have foreground absorption. Please refer to Table 1 of the paper to obtain molecular transition rest frequencies, energies, GBT beam sizes, and transition quantum numbers. (2 data files).

  6. CIRCUMSTELLAR MOLECULAR LINE ABSORPTION AND EMISSION IN THE OPTICAL-SPECTRA OF POST-AGB STARS

    NARCIS (Netherlands)

    BAKKER, EJ; LAMERS, HJGLM; WATERS, LBFM; SCHOENMAKER, T

    We present a list of post-AGB stars showing molecular line absorption and emission in the optical spectrum. Two objects show CH+, one in emission and one in absorption, and 10 stars show C-2 and CN in absorption. The Doppler velocities of the C-2 lines and the rotational temperatures indicate that

  7. C IV Broad Absorption Line Variability in QSO Spectra from SDSS Surveys

    Directory of Open Access Journals (Sweden)

    Demetra De Cicco

    2017-12-01

    Full Text Available Broad absorption lines (BALs in the spectra of quasi-stellar objects (QSOs are thought to arise from outflowing winds along our line of sight; winds, in turn, are thought to originate from the accretion disk, in the very surroundings of the central supermassive black hole (SMBH, and they likely affect the accretion process onto the SMBH, as well as galaxy evolution. BALs can exhibit variability on timescales typically ranging from months to years. We analyze such variability and, in particular, BAL disappearance, with the aim of investigating QSO physics and structure. We search for disappearing C IV BALs in the spectra of 1,319 QSOs from different programs from the Sloan Digital Sky Survey (SDSS; the analyzed time span covers 0.28–4.9 year (rest frame, and the source redshifts are in the range 1.68–4.27. This is to date the largest sample ever used for such a study. We find 67 sources (5.1-0.6+0.7% of the sample with 73 disappearing BALs in total (3.9-0.5+0.5% of the total number of C iv BALs detected; some sources have more than one BAL that disappears. We compare the sample of disappearing BALs to the whole sample of BALs, and investigate the correlation in the variability of multiple troughs in the same spectrum. We also derive estimates of the average lifetime of a BAL trough and of the BAL phase along our line of sight.

  8. XMM-Newton Survey of Local O VII Absorption Lines in the Spectra of Galactic X-Ray Sources

    Science.gov (United States)

    Luo, Yang; Fang, Taotao; Ma, Renyi

    2018-04-01

    The detection of highly ionized metal absorption lines in the X-ray spectra of the Galactic X-ray binaries (XRBs) implies the distribution of hot gas along the sightline toward the background sources. However, the origin of this hot gas is still unclear: it can arise in the hot interstellar medium (ISM), or is intrinsic to the XRBs. In this paper, we present an XMM-Newton survey of the O VII absorption lines in the spectra of Galactic XRBs. A total of 33 XRBs were selected, with 29 low-mass XRBs and 4 high-mass XRBs. At a more than 3σ threshold, O VII absorption line was detected in 16 targets, among which 4 were newly discovered in this work. The average line equivalent width is centered around ∼20 mÅ. Additionally, we do not find strong correlations between the O VII EWs and the Galactic neutral absorption N H, the Galactic coordinates, or the distance of background targets. Such non-correlation may suggest contamination of the circumstellar material, or a lack of constraints on the line Doppler-b parameter. We also find that regardless of the direction of the XRBs, the O VII absorption lines are always detected when the flux of the background XRBs reaches a certain level, suggesting a uniform distribution of this hot gas. We estimate a ratio of 0.004–0.4 between the hot and neutral phases of the ISM. This is the second paper in the series following Fang et al. (2015), in which we focused on the local O VII absorption lines detected in the background AGN spectra. Detailed modeling of the hot ISM distribution will be investigated in a future paper.

  9. Interstellar absorption lines in high-resolution IUE spectra of cataclysmic variables

    International Nuclear Information System (INIS)

    Mauche, C.W.; Raymond, J.C.; Cordova, F.A.

    1988-01-01

    High-resolution ultraviolet spectra of five cataclysmic variables obtained with the IUE are used to investigate the character of the interstellar medium in the vicinity of the sun. These spectra reveal narrow absorption features of neutral and singly ionized interstellar species, and, in SS Cyg, narrow velocity-shifted absorption features of C IV, Si IV, and Si III. Using the column densities implied by the absorption features of the neutral and singly ionized species, values for the depletion of Si, Mg, Mn, and Fe from the gas phase of the interstellar medium in the vicinity of the sun are obtained. These hydrogen column densities are of particular importance in constraining the soft X-ray luminosity of cataclysmic variables because of the severe attenuation of the soft X-ray flux of cataclysmic variables by photoelectric absorption in the interstellar medium. In addition, using the column densities implied by the absorption features of C IV, Si IV, and Si III in the spectrum of SS Cyg, the existence of an expanding H II region of interstellar gas photoionized by he EUV and soft X-ray flux of this cataclysmic variable are inferred. 78 references

  10. The SLUGGS survey: globular cluster stellar population trends from weak absorption lines in stacked spectra

    Science.gov (United States)

    Usher, Christopher; Forbes, Duncan A.; Brodie, Jean P.; Romanowsky, Aaron J.; Strader, Jay; Conroy, Charlie; Foster, Caroline; Pastorello, Nicola; Pota, Vincenzo; Arnold, Jacob A.

    2015-01-01

    As part of the SAGES Legacy Unifying Globulars and GalaxieS (SLUGGS) survey, we stack 1137 Keck DEIMOS (Deep Imaging Multi-Object Spectrograph) spectra of globular clusters from 10 galaxies to study their stellar populations in detail. The stacked spectra have median signal-to-noise ratios of ˜90 Å-1. Besides the calcium triplet, we study weaker sodium, magnesium, titanium and iron lines as well as the Hα and higher order Paschen hydrogen lines. In general, the stacked spectra are consistent with old ages and a Milky Way-like initial mass function. However, we see different metal line index strengths at fixed colour and magnitude, and differences in the calcium triplet-colour relation from galaxy to galaxy. We interpret this as strong evidence for variations in the globular cluster colour-metallicity relation between galaxies. Two possible explanations for the colour-metallicity relation variations are that the average ages of globular clusters vary from galaxy to galaxy or that the average abundances of light elements (i.e. He, C, N and O) differ between galaxies. Stacking spectra by magnitude, we see that the colours become redder and metal line indices stronger with brighter magnitudes. These trends are consistent with the previously reported `blue tilts' being mass-metallicity relations.

  11. Impact of broadened laser line-shape on retrievals of atmospheric species from lidar sounding absorption spectra.

    Science.gov (United States)

    Chen, Jeffrey R; Numata, Kenji; Wu, Stewart T

    2015-02-09

    We examine the impact of broadened laser line-shape on retrievals of atmospheric species from lidar-sounding absorption spectra. The laser is assumed to be deterministically modulated into a stable, nearly top-hat frequency comb to suppress the stimulated Brillouin scattering, allowing over 10-fold pulse energy increase without adding measurement noise. Our model remains accurate by incorporating the laser line-shape factor into the effective optical depth. Retrieval errors arising from measurement noise and model bias are analyzed parametrically and numerically to provide deeper insight. The stable laser line-shape broadening minimally degrades the column-averaged retrieval, but can significantly degrade the multiple-layer retrievals.

  12. Effect of a progressive sound wave on the profiles of spectral lines. 2: Asymmetry of faint Fraunhofer lines. [absorption spectra

    Science.gov (United States)

    Kostyk, R. I.

    1974-01-01

    The absorption coefficient profile was calculated for lines of different chemical elements in a medium with progressive sound waves. Calculations show that (1) the degree and direction of asymmetry depend on the atomic ionization potential and the potential of lower level excitation of the individual line; (2) the degree of asymmetry of a line decreases from the center toward the limb of the solar disc; and (3) turbulent motions 'suppress' the asymmetry.

  13. Modelling High Resolution Absorption Spectra with ExoMolLine Lists: NH3and CH4

    DEFF Research Database (Denmark)

    Barton, E. J.; Yurchenko, S. N.; Tennyson, J.

    The conditions, chemical reactions and gas mixing in industrial progresses involving gasification or combustion can be monitored by in situ measurement of gas temperature and gas composition. This can be done spectroscopically, though the result is highly dependent on the quality of reference data...... [1]. For this reason, a smart collaboration has been established between Optical Diagnostics Group at DTU and ExoMol, to combine high resolution spectra measured at elevated temperatures and empirically tuned ab initio methods to produce suitable molecular line lists for modelling molecules...

  14. Testing Accretion Disk Wind Models of Broad Absorption Line Quasars with SDSS Spectra

    Science.gov (United States)

    Lindgren, Sean; Gabel, Jack

    2017-06-01

    We present an investigation of a large sample of broad absorption line (BAL) quasars (QSO) from the Sloan Digital Sky Survey (SDSS) Data Release 5 (DR5). Properties of the BALs, such as absorption equivalent width, outflow velocities, and depth of BAL, are obtained from analysis by Gibson et al. We perform correlation analysis on these data to test the predictions made by the radiation driven, accretion disk streamline model of Murray and Chiang. We find the CIV BAL maximum velocity and the continuum luminosity are correlated, consistent with radiation driven models. The mean minimum velocity of CIV is lower in low ionization BALs (LoBALs), than highly ionized BALs (HiBALS), suggesting an orientation effect consistent with the Murray and Chiang model. Finally, we find that HiBALs greatly outnumber LoBALs in the general BAL population, supporting prediction of the Murray and Chiang model that HiBALs have a greater global covering factor than LoBALs.

  15. X-ray absorption spectra and emission spectra of plasmas

    International Nuclear Information System (INIS)

    Peng Yonglun; Yang Li; Wang Minsheng; Li Jiaming

    2002-01-01

    The author reports a theoretical method to calculate the resolved absorption spectra and emission spectra (optically thin) of hot dense plasmas. Due to its fully relativistic treatment incorporated with the quantum defect theory, it calculates the absorption spectra and emission spectra for single element or multi-element plasmas with little computational efforts. The calculated absorption spectra of LTE gold plasmas agree well with the experimental ones. It also calculates the optical thin emission spectra of LTE gold plasmas, which is helpful to diagnose the plasmas of relevant ICF plasmas. It can also provide the relevant parameters such as population density of various ionic stages, precise radiative properties for ICF studies

  16. Electronic absorption spectra of antiviral aminophenol derivatives

    Science.gov (United States)

    Belkov, M. V.; Ksendzova, G. A.; Raichyonok, T. F.; Skornyakov, I. V.; Sorokin, V. L.; Tolstorozhev, G. B.; Shadyro, O. I.

    2011-03-01

    Electronic absorption spectra of aminophenol derivatives in solutions have been studied. A general property of the absorption spectra of these compounds, the dependence of the maximum of a long-wavelength absorption band on the solvent polarity, is revealed. As a rule, the absorption band maximum of compounds possessing pharmacological properties shows a greater shift to short wavelength with an increase in the medium polarity than that of inactive compounds. Absorption measurements of solutions of aminophenol derivatives can be used for a tentative estimation of their antiviral activity.

  17. Optical absorption spectra of Ag-11 isomers

    DEFF Research Database (Denmark)

    Martinez, Jose Ignacio; Fernandez, E. M.

    2009-01-01

    The optical absorption spectra of the three most; stable structural isomers of the Ag-11 cluster were calculated using the time-dependent, density functional theory within the Casida formalism. The slightly different, spectra, of the isomers may permit the identification of the ground-stale confi......The optical absorption spectra of the three most; stable structural isomers of the Ag-11 cluster were calculated using the time-dependent, density functional theory within the Casida formalism. The slightly different, spectra, of the isomers may permit the identification of the ground...

  18. Uncertainty analysis for absorption and first-derivative EPR spectra

    Science.gov (United States)

    Tseitlin, Mark; Eaton, Sandra S.; Eaton, Gareth R.

    2015-01-01

    Electron paramagnetic resonance (EPR) experimental techniques produce absorption or first-derivative spectra. Uncertainty analysis provides the basis for comparison of spectra obtained by different methods. In this study it was used to derive analytical equations to relate uncertainties for integrated intensity and line widths obtained from absorption or first-derivative spectra to the signal-to-noise ratio (SNR), with the assumption of white noise. Predicted uncertainties for integrated intensities and line widths are in good agreement with Monte Carlo calculations for Lorentzian and Gaussian lineshapes. Conservative low-pass filtering changes the noise spectrum, which can be modeled in the Monte Carlo simulations. When noise is close to white, the analytical equations provide useful estimates of uncertainties. For example, for a Lorentzian line with white noise, the uncertainty in the number of spins obtained from the first-derivative spectrum is 2.6 times greater than from the absorption spectrum at the same SNR. Uncertainties in line widths obtained from absorption and first-derivative spectra are similar. The impact of integration or differentiation on SNR and on uncertainties in fitting parameters was analyzed. Although integration of the first-derivative spectrum improves the apparent smoothness of the spectrum, it also changes the frequency distribution of the noise. If the lineshape of the signal is known, the integrated intensity can be determined more accurately by fitting the first-derivative spectrum than by first integrating and then fitting the absorption spectrum. Uncertainties in integrated intensities and line widths are less when the parameters are determined from the original data than from spectra that have been either integrated or differentiated. PMID:25774102

  19. Absorption spectra of AA-stacked graphite

    International Nuclear Information System (INIS)

    Chiu, C W; Lee, S H; Chen, S C; Lin, M F; Shyu, F L

    2010-01-01

    AA-stacked graphite shows strong anisotropy in geometric structures and velocity matrix elements. However, the absorption spectra are isotropic for the polarization vector on the graphene plane. The spectra exhibit one prominent plateau at middle energy and one shoulder structure at lower energy. These structures directly reflect the unique geometric and band structures and provide sufficient information for experimental fitting of the intralayer and interlayer atomic interactions. On the other hand, monolayer graphene shows a sharp absorption peak but no shoulder structure; AA-stacked bilayer graphene has two absorption peaks at middle energy and abruptly vanishes at lower energy. Furthermore, the isotropic features are expected to exist in other graphene-related systems. The calculated results and the predicted atomic interactions could be verified by optical measurements.

  20. Calculated Hanle transmission and absorption spectra of the 87Rb D1 line with residual magnetic field for arbitrarily polarized light

    International Nuclear Information System (INIS)

    Noh, Heung-Ryoul; Moon, Han Seb

    2010-01-01

    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.

  1. Absorption Spectra of Gold Nanoparticle Suspensions

    Science.gov (United States)

    Anan'eva, M. V.; Nurmukhametov, D. R.; Zverev, A. S.; Nelyubina, N. V.; Zvekov, A. A.; Russakov, D. M.; Kalenskii, A. V.; Eremenko, A. N.

    2018-02-01

    Three gold nanoparticle suspensions are obtained, and mean radii in distributions - (6.1 ± 0.2), (11.9 ± 0.3), and (17.3 ± 0.7) nm - are determined by the transmission electron microscopy method. The optical absorption spectra of suspensions are obtained and studied. Calculation of spectral dependences of the absorption index of suspensions at values of the gold complex refractive index taken from the literature showed a significant deviation of experimental and calculated data in the region of 450-800 nm. Spectral dependences of the absorption of suspensions are simulated within the framework of the Mie-Drude theory taking into account the interband absorption in the form of an additional term in the imaginary part of the dielectric permittivity of the Gaussian type. It is shown that to quantify the spectral dependences in the region of the plasmon absorption band of nanoparticles, correction of the parameters of the interband absorption is necessary in addition to the increase of the relaxation parameter of the Drude theory. Spectral dependences of the dielectric permittivity of gold in nanodimensional state are refined from the solution of the inverse problem. The results of the present work are important for predicting the special features of operation of photonic devices and optical detonators based on gold nanoparticles.

  2. Spectrophotometry of six broad absorption line QSOs

    Science.gov (United States)

    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.

  3. Molecular geometry in the ultraviolet absorption spectra

    International Nuclear Information System (INIS)

    Albuquerque, S.F. de; Monteiro, L.S.; Adamis, L.M.B.; Baltar, M.C.P.; Silva, R.M. da

    1977-01-01

    The ultraviolet absorption spectra may be sensibly affected by steric effects. These effects can cause a lot of difficulties and unexpected changes in spectrum. The most general source of such difficulties is steric inhibition of resonance. In addition to this, ultraviolet epectra may be markedly changed by steric factors which change the positions of dipoles in the molecule with respect to each other and by the interaction of nonconjugated chromophores suitably located in space. We have studied in detail each of these effects presenting a lot of usual and importants examples in Organic Chemistry. Others relevants subjects were not considerated in this present work [pt

  4. Investigation of IR absorption spectra of oral cavity bacteria

    Science.gov (United States)

    Belikov, Andrei V.; Altshuler, Gregory B.; Moroz, Boris T.; Pavlovskaya, Irina V.

    1996-12-01

    The results of comparative investigation for IR and visual absorption spectra of oral cavity bacteria are represented by this paper. There are also shown the main differences in absorption spectra of such pure bacteria cultures as : E- coli, Candida, Staph, Epidermidis, and absorption spectra of bacteria colonies cultured in tooth root canals suspected to harbour several endodontical problems. The results of experimental research targeted to investigate an effect of such combined YAG:Nd and YAG:Cr; Tm; Ho laser parameters like: wavelength, energy density, average power and etc., to oral cavity bacteria deactivation are given finally.

  5. Theoretical Atomic Physics code development IV: LINES, A code for computing atomic line spectra

    International Nuclear Information System (INIS)

    Abdallah, J. Jr.; Clark, R.E.H.

    1988-12-01

    A new computer program, LINES, has been developed for simulating atomic line emission and absorption spectra using the accurate fine structure energy levels and transition strengths calculated by the (CATS) Cowan Atomic Structure code. Population distributions for the ion stages are obtained in LINES by using the Local Thermodynamic Equilibrium (LTE) model. LINES is also useful for displaying the pertinent atomic data generated by CATS. This report describes the use of LINES. Both CATS and LINES are part of the Theoretical Atomic PhysicS (TAPS) code development effort at Los Alamos. 11 refs., 9 figs., 1 tab

  6. Broad Absorption Line Quasar catalogues with Supervised Neural Networks

    International Nuclear Information System (INIS)

    Scaringi, Simone; Knigge, Christian; Cottis, Christopher E.; Goad, Michael R.

    2008-01-01

    We have applied a Learning Vector Quantization (LVQ) algorithm to SDSS DR5 quasar spectra in order to create a large catalogue of broad absorption line quasars (BALQSOs). We first discuss the problems with BALQSO catalogues constructed using the conventional balnicity and/or absorption indices (BI and AI), and then describe the supervised LVQ network we have trained to recognise BALQSOs. The resulting BALQSO catalogue should be substantially more robust and complete than BI-or AI-based ones.

  7. Protonation effects on the UV/Vis absorption spectra of imatinib: A theoretical and experimental study

    Science.gov (United States)

    Grante, Ilze; Actins, Andris; Orola, Liana

    2014-08-01

    An experimental and theoretical investigation of protonation effects on the UV/Vis absorption spectra of imatinib showed systematic changes of absorption depending on the pH, and a new absorption band appeared below pH 2. These changes in the UV/Vis absorption spectra were interpreted using quantum chemical calculations. The geometry of various imatinib cations in the gas phase and in ethanol solution was optimized with the DFT/B3LYP method. The resultant geometries were compared to the experimentally determined crystal structures of imatinib salts. The semi-empirical ZINDO-CI method was employed to calculate the absorption lines and electronic transitions. Our study suggests that the formation of the extra near-UV absorption band resulted from an increase of imatinib trication concentration in the solution, while the rapid increase of the first absorption maximum could be attributed to both the formation of imatinib trication and tetracation.

  8. The Effect of Phonon Relaxation Process on Absorption Spectra ...

    African Journals Online (AJOL)

    In this work we study the effect of phonon relaxation process on the absorption spectra using the Green's function technique. The Green's function technique which is widely used in many particle problems is used to solve the Kubo formula which describes the optical absorption process. Finally the configurational diagram is ...

  9. Helium shells and faint emission lines from slitless flash spectra.

    Science.gov (United States)

    Bazin, Cyril; Koutchmy, Serge

    2013-05-01

    At the time of the two last solar total eclipses of August 1st, 2008 in Siberia and July 11th, 2010 in French Polynesia, high frame rate CCD flash spectra were obtained. These eclipses occurred in quiet Sun period and after. The slitless flash spectra show two helium shells, in the weak Paschen α 4686 Å line of the ionized helium HeII and in the neutral helium HeI line at 4713 Å. The extensions of these helium shells are typically 3 Mm. In prominences, the extension of the interface with the corona is much more extended. The observations and analysis of these lines can properly be done only in eclipse conditions, when the intensity threshold reaches the coronal level, and the parasitic scattered light is virtually zero. Under the layers of 1 Mm above the limb, many faint low FIP lines were also seen in emission. These emission lines are superposed on the continuum containing absorption lines. The solar limb can be defined using the weak continuum appearing between the emission lines at the time of the second and third contact. The variations of the singly ionized iron line, the HeI and HeII lines and the continuum intensity are analyzed. The intensity ratio of ionized to neutral helium is studied for evaluating the ionization rate in low layers up to 2 Mm and also around a prominence.

  10. The Sloan Digital Sky Survey QSO absorption line catalogue

    Science.gov (United States)

    York, Donald G.; vanden Berk, Daniel; Richards, Gordon T.; Crotts, Arlin P. S.; Khare, Pushpa; Lauroesch, James; Lemoine, Martin; Burles, Scott; Bernardi, Mariangela; Castander, Francisco J.; Frieman, Josh; Loveday, Jon; Meiksin, Avery; Nichol, Robert; Schlegel, David; Schneider, Donald P.; Subbarao, Mark; Stoughton, Chris; Szalay, Alex; Yanny, Brian; Alsayyad, Yusra; Kumar, Abhishek; Lundgren, Britt; Shanidze, Natela; Vanlandingham, Johnny; Wood, Matthew; Baugher, Britt; Brinkmann, Jon; Brunner, Robert; Fukugita, Masaaka; Hall, Patrick B.; Heckman, Timothy M.; Hobbs, Lewis M.; Hogan, Craig J.; Hui, Lam; Jenkins, Edward B.; Kunstz, Daniel; Menard, Brice; Nakamura, Osamu; Quashnock, Jean M.; Stein, Michael; Thakar, Aniruddha R.; Turnshek, David; Welty, Daniel E.; SDSS Collaboration

    2005-03-01

    The spectra of the Sloan Digital Sky Survey (SDSS) are being used to construct a catalogue of QSO absorption lines, for use in studies of abundances, relevant radiation fields, number counts as a function of redshift, and other matters, including the evolution of these parameters. The catalogue includes intervening, associated, and BAL absorbers, in order to allow a clearer definition of the relationships between these three classes. We describe the motivation for and the data products of the project to build the SDSS QSO absorption line catalogue.

  11. Extreme Variability in a Broad Absorption Line Quasar

    Energy Technology Data Exchange (ETDEWEB)

    Stern, Daniel; Jun, Hyunsung D. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Mail Stop 169-221, Pasadena, CA 91109 (United States); Graham, Matthew J.; Djorgovski, S. G.; Donalek, Ciro; Drake, Andrew J.; Mahabal, Ashish A.; Steidel, Charles C. [California Institute of Technology, 1200 E. California Boulevard, Pasadena, CA 91125 (United States); Arav, Nahum; Chamberlain, Carter [Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States); Barth, Aaron J. [Department of Physics and Astronomy, 4129 Frederick Reines Hall, University of California, Irvine, CA 92697 (United States); Glikman, Eilat, E-mail: daniel.k.stern@jpl.nasa.gov [Department of Physics, Middlebury College, Middlebury, VT 05753 (United States)

    2017-04-20

    CRTS J084133.15+200525.8 is an optically bright quasar at z = 2.345 that has shown extreme spectral variability over the past decade. Photometrically, the source had a visual magnitude of V ∼ 17.3 between 2002 and 2008. Then, over the following five years, the source slowly brightened by approximately one magnitude, to V ∼ 16.2. Only ∼1 in 10,000 quasars show such extreme variability, as quantified by the extreme parameters derived for this quasar assuming a damped random walk model. A combination of archival and newly acquired spectra reveal the source to be an iron low-ionization broad absorption line quasar with extreme changes in its absorption spectrum. Some absorption features completely disappear over the 9 years of optical spectra, while other features remain essentially unchanged. We report the first definitive redshift for this source, based on the detection of broad H α in a Keck/MOSFIRE spectrum. Absorption systems separated by several 1000 km s{sup −1} in velocity show coordinated weakening in the depths of their troughs as the continuum flux increases. We interpret the broad absorption line variability to be due to changes in photoionization, rather than due to motion of material along our line of sight. This source highlights one sort of rare transition object that astronomy will now be finding through dedicated time-domain surveys.

  12. Theoretical study on absorption and emission spectra of adenine analogues.

    Science.gov (United States)

    Liu, Hongxia; Song, Qixia; Yang, Yan; Li, Yan; Wang, Haijun

    2014-04-01

    Fluorescent nucleoside analogues have attracted much attention in studying the structure and dynamics of nucleic acids in recent years. In the present work, we use theoretical calculations to investigate the structural and optical properties of four adenine analogues (termed as A1, A2, A3, and A4), and also consider the effects of aqueous solution and base pairing. The results show that the fluorescent adenine analogues can pair with thymine to form stable H-bonded WC base pairs. The excited geometries of both adenine analogues and WC base pairs are similar to the ground geometries. The absorption and emission maxima of adenine analogues are greatly red shifted compared with nature adenine, the oscillator strengths of A1 and A2 are stronger than A3 and A4 in both absorption and emission spectra. The calculated low-energy peaks in the absorption spectra are in good agreement with the experimental data. In general, the aqueous solution and base pairing can slightly red-shift both the absorption and emission maxima, and can increase the oscillator strengths of absorption spectra, but significantly decrease the oscillator strengths of A3 in emission spectra.

  13. Narrow absorption lines complex I: one form of broad absorption line

    Science.gov (United States)

    Lu, Wei-Jian; Lin, Ying-Ru

    2018-03-01

    We discover that some of the broad absorption lines (BALs) are actually a complex of narrow absorption lines (NALs). As a pilot study of this type of BAL, we show this discovery through a typical example in this paper. Utilizing the two-epoch observations of J002710.06-094435.3 (hereafter J0027-0944) from the Sloan Digital Sky Survey (SDSS), we find that each of the C IV and Si IV BAL troughs contains at least four NAL doublets. By resolving the Si IV BAL into multiple NALs, we present the following main results and conclusions. First, all these NALs show coordinated variations between the two-epoch SDSS observations, suggesting that they all originate in the quasar outflow, and that their variations are due to global changes in the ionization condition of the absorbing gas. Secondly, a BAL consisting of a number of NAL components indicates that this type of BAL is basically the same as the intrinsic NAL, which tends to support the inclination model rather than the evolution model. Thirdly, although both the C IV and Si IV BALs originate from the same clumpy substructures of the outflow, they show different profile shapes: multiple absorption troughs for the Si IV BAL in a wider velocity range, while P-Cygni for the C IV BAL in a narrower velocity range. This can be interpreted by the substantial differences in fine structure and oscillator strength between the Si IVλλ1393, 1402 and C IVλλ1548, 1551 doublets. Based on the above conclusions, we consider that the decomposition of a BAL into NALs can serve as a way to resolve the clumpy structure for outflows, and it can be used to learn more about characteristics of the clumpy structure and to test the outflow model, when utilizing high-resolution spectra and photoionization model.

  14. [A new automated method to identify emission line star from massive spectra].

    Science.gov (United States)

    Pan, Jing-Chang; Zhang, Cai-Ming; Wei, Peng; Luo, A-Li; Zhao, Yong-Heng

    2012-06-01

    Stellar spectra are characterized by obvious absorption lines or absorption bands, while those with emission lines are usually special stars such as cataclysmic variable stars (CVs), HerbigAe/Be etc. The further study of this kind of spectra is meaningful. The present paper proposed a new method to identify emission line stars (ELS) spectra automatically. After the continuum normalization is done for the original spectral flux, line detection is made by comparing the normalized flux with the mean and standard deviation of the flux in its neighbor region The results of the experiment on massive spectra from SDSS DR8 indicate that the method can identify ELS spectra completely and accurately. Since no complex transformation and computation are involved in this method, the identifying process is fast and it is ideal for the ELS detection in large sky survey projects like LAMOST and SDSS.

  15. Sub-millimetre wave absorption spectra of artificial RNA molecules

    CERN Document Server

    Globus, T; Woolard, D; Gelmont, B

    2003-01-01

    We demonstrate submillimetre-wave Fourier transform spectroscopy as a novel technique for biological molecule characterization. Transmission measurements are reported at frequencies 10-25 cm sup - sup 1 for single- and double-stranded RNA molecules of known base-pair sequences: homopolymers poly[A], poly[U], poly[C] and poly[G], and double-stranded homopolymers poly[A]-poly[U] and poly[C]-poly[G]. Multiple resonances are observed (i.e. in the microwave through terahertz frequency regime). We also present a computational method to predict the low-frequency absorption spectra of short artificial DNA and RNA. Theoretical conformational analysis of molecules was utilized to derive the low-frequency vibrational modes. Oscillator strengths were calculated for all the vibrational modes in order to evaluate their weight in the absorption spectrum of a molecule. Normal modes and absorption spectra of the double-stranded RNA chain poly[C]-poly[G] were calculated. The absorption spectra extracted from the experiment wer...

  16. Absorption line spectroscopy of the interstellar medium

    International Nuclear Information System (INIS)

    Jura, M.

    1983-01-01

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

  17. Fe II emission lines. I - Chromospheric spectra of red giants

    Science.gov (United States)

    Judge, P. G.; Jordan, C.

    1991-01-01

    A 'difference filtering' algorithm developed by Ayers (1979) is used to construct high-quality high-dispersion long-wavelength IUE spectra of three giant stars. Measurements of all the emission lines seen between 2230 and 3100 A are tabulated. The emission spectrum of Fe II is discussed in comparison with other lines whose formation mechanisms are well understood. Systematic changes in the Fe II spectrum are related to the different physical conditions in the three stars, and examples are given of line profiles and ratios which can be used to determine conditions in the outer atomspheres of giants. It is concluded that most of the Fe II emission results from collisional excitation and/or absorption of photospheric photons at optical wavelengths, but some lines are formed by fluorescence, being photoexcited by other strong chromospheric lines. Between 10 and 20 percent of the radiative losses of Fe II arise from 10 eV levels radiatively excited by the strong chromospheric H Ly-alpha line.

  18. Gigahertz-peaked Spectra Pulsars and Thermal Absorption Model

    Energy Technology Data Exchange (ETDEWEB)

    Kijak, J.; Basu, R.; Lewandowski, W.; Rożko, K. [Janusz Gil Institute of Astronomy, University of Zielona Góra, ul. Z. Szafrana 2, PL-65-516 Zielona Góra (Poland); Dembska, M., E-mail: jkijak@astro.ia.uz.zgora.pl [DLR Institute of Space Systems, Robert-Hooke-Str. 7 D-28359 Bremen (Germany)

    2017-05-10

    We present the results of our radio interferometric observations of pulsars at 325 and 610 MHz using the Giant Metrewave Radio Telescope. We used the imaging method to estimate the flux densities of several pulsars at these radio frequencies. The analysis of the shapes of the pulsar spectra allowed us to identify five new gigahertz-peaked spectra (GPS) pulsars. Using the hypothesis that the spectral turnovers are caused by thermal free–free absorption in the interstellar medium, we modeled the spectra of all known objects of this kind. Using the model, we were able to put some observational constraints on the physical parameters of the absorbing matter, which allows us to distinguish between the possible sources of absorption. We also discuss the possible effects of the existence of GPS pulsars on future search surveys, showing that the optimal frequency range for finding such objects would be from a few GHz (for regular GPS sources) to possibly 10 GHz for pulsars and radio magnetars exhibiting very strong absorption.

  19. Photothermal Determination of Absorption and Scattering Spectra of Silver Nanoparticles.

    Science.gov (United States)

    Marcano Olaizola, Aristides

    2018-02-01

    This work reports on photothermal lens spectra of silver nanoparticles of different dimensions in the spectral region of 370-730 nm performed using an arc-lamp-based photothermal spectrophotometer. We show that the photothermal and extinction cross-section spectra of the samples are similar for nanoparticles of reduced dimensions where scattering effects are small. The results differ substantially for nanoparticles of a diameter larger than 30 nm for which scattering becomes relevant. We demonstrate that the photothermal spectrum corresponds to the absorption component of the particle's extinction. Photothermal spectra show a clear picture of the plasmonic peaks of the nanoparticle even in the presence of high scattering. By subtracting the photothermal component from the total extinction, we extract the scattering cross-section spectra of the nanoparticles. The technique allows determination of the absorption and scattering components of the extinction providing a better understanding of the particle's optical properties. The results agree well with the Mie approximation, which is valid for a single spherical nanoparticle. We discuss and demonstrate the application of the method to characterize particles of arbitrary shape and dimensions.

  20. Absorption lines, Faraday rotation, and magnetic field estimates for QSO absorption-line clouds

    International Nuclear Information System (INIS)

    Kronberg, P.P.; Perry, J.J.

    1982-01-01

    We have estimated the extragalactic component of Faraday rotation for a sample of 37 QSOs for which there is good absorption line data, which we have also analyzed. Statistical evidence is presented which suggests that we have isolated a component of Faraday rotation which is occurring in the absorption clouds of some QSOs

  1. Electronic absorption spectra and geometry of organic molecules an application of molecular orbital theory

    CERN Document Server

    Suzuki, Hiroshi

    1967-01-01

    Electronic Absorption Spectra and Geometry of Organic Molecules: An Application of Molecular Orbital Theory focuses on electronic absorption spectra of organic compounds and molecules. The book begins with the discussions on molecular spectra, electronic absorption spectra of organic compounds, and practical measures of absorption intensity. The text also focuses on molecular orbital theory and group theory. Molecular state functions; fundamental postulates of quantum theory; representation of symmetry groups; and symmetry operations and symmetry groups are described. The book also dis

  2. Ultraviolet absorption spectra of cis and trans potassium peroxynitrite (KOONO) in solid argon

    Science.gov (United States)

    Lo, Wen-Jui; Lee, Yuan-Pern; Tsai, Jyh-Hsin M.; Beckman, Joseph S.

    1995-08-01

    Two conformers (cis and trans) of potassium peroxynitrite (KOONO) were produced in an argon matrix containing potassium nitrate (KNO 3) at 13 K by means of in situ photolysis with an ArF excimer laser at 193 nm. Photoconversion among cis- and trans-KOONO, and KNO 3, was achieved on irradiation of the matrix with a laser at varied wavelengths. With the aid of the relative intensities of IR absorption lines observed for each species at each stage of photolysis, the UV absorption spectra of cis- and trans-KOONO were determined. The absorption maxima, near 325 and 375 nm for cis- and trans-KOONO, respectively, agree with theoretical calculations by Krauss. The photolytic behavior of both conformers at varied wavelengths can be understood in relation to the observed UV absorptions.

  3. Observations of Absorption Lines from Highly Ionized Atoms

    Science.gov (United States)

    Jenkins, E. B.

    1984-01-01

    In the ultraviolet spectra of hot stars, absorption lines can be seen from highly ionized species in the interstellar medium. Observations of these features which have been very influential in revising the perception of the medium's various physical states, are discussed. The pervasiveness of O 6 absorption lines, coupled with complementary observations of a diffuse background in soft X-rays and EUV radiation, shows that there is an extensive network of low density gas (n approx. fewX 0.001/cucm) existing at coronal temperatures, 5.3 or = log T or = 6.3. Shocks created by supernova explosions or mass loss from early-type stars can propagate freely through space and eventually transfer a large amount of energy to the medium. To create the coronal temperatures, the shocks must have velocities in excess of 150 km/sec; shocks at somewhat lower velocity 9v or = 100 km/sec) can be directly observed in the lines of Si3. Observations of other lines in the ultraviolet, such as Si 4V and C 5, may highlight the widespread presence of energetic uv radiation from very hot, dward stars. More advanced techniques in visible and X-ray astronomical spectroscopy may open up for inspection selected lines from atoms in much higher stages of ionization.

  4. Modelling telluric line spectra in the optical and infrared with an application to VLT/X-Shooter spectra

    Science.gov (United States)

    Rudolf, N.; Günther, H. M.; Schneider, P. C.; Schmitt, J. H. M. M.

    2016-01-01

    Context. Earth's atmosphere imprints a large number of telluric absorption and emission lines on astronomical spectra, especially in the near infrared, that need to be removed before analysing the affected wavelength regions. Aims: These lines are typically removed by comparison to A- or B-type stars used as telluric standards that themselves have strong hydrogen lines, which complicates the removal of telluric lines. We have developed a method to circumvent that problem. Methods: For our IDL software package tellrem we used a recent approach to model telluric absorption features with the line-by-line radiative transfer model (LBLRTM). The broad wavelength coverage of the X-Shooter at VLT allows us to expand their technique by determining the abundances of the most important telluric molecules H2O, O2, CO2, and CH4 from sufficiently isolated line groups. For individual observations we construct a telluric absorption model for most of the spectral range that is used to remove the telluric absorption from the object spectrum. Results: We remove telluric absorption from both continuum regions and emission lines without systematic residuals for most of the processable spectral range; however, our method increases the statistical errors. The errors of the corrected spectrum typically increase by 10% for S/N ~ 10 and by a factor of two for high-quality data (S/N ~ 100), I.e. the method is accurate on the percent level. Conclusions: Modelling telluric absorption can be an alternative to the observation of standard stars for removing telluric contamination. Based on observations collected at the European Southern Observatory, Paranal, Chile, 085.C-0764(A) and 60.A-9022(C).The tellrem package is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/585/A113

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

    NARCIS (Netherlands)

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

    2017-01-01

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

  6. Infrared absorption spectra of selenate compounds of indium (3)

    International Nuclear Information System (INIS)

    Kharitonov, Yu.Ya.; Kadoshnikova, N.V.; Tananaev, I.V.

    1979-01-01

    Obtained and discussed are infrared absorption spectra (400-4000 cm -1 ) of the following indium selenates: In 2 (SeO 4 ) 3 x5H 2 O, In 2 (SeO 4 ) 3 x9H 2 O, NaIn(SeO 4 ) 2 x6H 2 O, NaIn(SeO 4 ) 2 xH 2 O, MIn(SeO 4 ) 2 x4H 2 O (M=NH 4 , K, Rb), CsIn(SeO 4 ) 2 x2H 2 O, Na 3 In(SeO 4 ) 3 x7H 2 O, MIn(SeO 4 ) 2 (M=NH 4 , Na, K, Rb, Cs), M 2 InOH(SeO 4 ) 2 xyH 2 O (M=NH 4 , Na, K, Rb) and K 2 InOD(SeO 4 ) 2 xyD 2 O

  7. Particulate absorption properties in the Red Sea from hyperspectral particulate absorption spectra

    KAUST Repository

    Tiwari, Surya Prakash

    2018-03-16

    This paper aims to describe the variability of particulate absorption properties using a unique hyperspectral dataset collected in the Red Sea as part of the TARA Oceans expedition. The absorption contributions by phytoplankton (aph) and non-algal particles (aNAP) to the total particulate absorption coefficients are determined using a numerical decomposition method (NDM). The NDM is validated by comparing the NDM derived values of aph and aNAP with simulated values of aph and aNAP are found to be in excellent agreement for the selected wavelengths (i.e., 443, 490, 555, and 676nm) with high correlation coefficient (R2), low root mean square error (RMSE), mean relative error (MRE), and with a slope close to unity. Further analyses showed that the total particulate absorption coefficients (i.e., ap(443)average = 0.01995m−1) were dominated by phytoplankton absorption (i.e., aph(443)average = 0.01743m−1) with a smaller contribution by non-algal particles absorption (i.e., aNAP(443)average = 0.002524m−1). The chlorophyll a is computed using the absorption based Line Height Method (LHM). The derived chlorophyll-specific absorption ((a⁎ph = aph(λ)/ChlLH)) showed more variability in the blue part of spectrum as compared to the red part of spectrum representative of the package effect and changes in pigment composition. A new parametrization proposed also enabled the reconstruction of a⁎ph(λ) for the Red Sea. Comparison of derived spectral constants with the spectral constants of existing models showed that our study A(λ) values are consistent with the existing values, despite there is a divergence with the B(λ) values. This study provides valuable information derived from the particulate absorption properties and its spectral variability and this would help us to determine the relationship between the phytoplankton absorption coefficients and chlorophyll a and its host of variables for the Red Sea.

  8. Emission-line spectra of QSOs and their redshifts

    International Nuclear Information System (INIS)

    Burbidge, E.M.

    1978-01-01

    A brief review of work on the emission-line spectra of QSOs is given. Data on radio-emitting and radio-quiet objects are discussed, with sections dealing with the lines that are observed, the distributions of red shifts obtained from the emission lines, and a selection of particular problems posed by current observations. These include a discussion of QSOs with atypical spectra, the Lyman/Balmer/Paschen relative line strengths, the abundances of the elements, correlations of observed properties, and gas flow within the emission-line region. (Auth.)

  9. Quasar outflow energetics from broad absorption line variability

    Science.gov (United States)

    McGraw, S. M.; Shields, J. C.; Hamann, F. W.; Capellupo, D. M.; Herbst, H.

    2018-03-01

    Quasar outflows have long been recognized as potential contributors to the co-evolution between supermassive black holes (SMBHs) and their host galaxies. The role of outflows in active galactic nucleus (AGN) feedback processes can be better understood by placing observational constraints on wind locations and kinetic energies. We utilize broad absorption line (BAL) variability to investigate the properties of a sample of 71 BAL quasars with P V broad absorption. The presence of P V BALs indicates that other BALs like C IV are saturated, such that variability in those lines favours clouds crossing the line of sight. We use these constraints with measurements of BAL variability to estimate outflow locations and energetics. Our data set consists of multiple-epoch spectra from the Sloan Digital Sky Survey and MDM Observatory. We detect significant (4σ) BAL variations from 10 quasars in our sample over rest-frame time-scales between ≤0.2-3.8 yr. Our derived distances for the 10 variable outflows are nominally ≲ 1-10 pc from the SMBH using the transverse-motion scenario, and ≲ 100-1000 pc from the central source using ionization-change considerations. These distances, in combination with the estimated high outflow column densities (i.e. NH ≳ 1022 cm-2), yield outflow kinetic luminosities between ˜ 0.001 and 1 times the bolometric luminosity of the quasar, indicating that many absorber energies within our sample are viable for AGN feedback.

  10. A Parallel Iterative Method for Computing Molecular Absorption Spectra.

    Science.gov (United States)

    Koval, Peter; Foerster, Dietrich; Coulaud, Olivier

    2010-09-14

    We describe a fast parallel iterative method for computing molecular absorption spectra within TDDFT linear response and using the LCAO method. We use a local basis of "dominant products" to parametrize the space of orbital products that occur in the LCAO approach. In this basis, the dynamic polarizability is computed iteratively within an appropriate Krylov subspace. The iterative procedure uses a matrix-free GMRES method to determine the (interacting) density response. The resulting code is about 1 order of magnitude faster than our previous full-matrix method. This acceleration makes the speed of our TDDFT code comparable with codes based on Casida's equation. The implementation of our method uses hybrid MPI and OpenMP parallelization in which load balancing and memory access are optimized. To validate our approach and to establish benchmarks, we compute spectra of large molecules on various types of parallel machines. The methods developed here are fairly general, and we believe they will find useful applications in molecular physics/chemistry, even for problems that are beyond TDDFT, such as organic semiconductors, particularly in photovoltaics.

  11. Infrared absorption spectra of nanosized silica with organic additives

    Directory of Open Access Journals (Sweden)

    Мaria О. Savchenko

    2014-12-01

    Full Text Available The prospects of using of silica nanoparticles modified with urea-formaldehyde polymers which is obtained by sulfuric acid sol-gel technology are shown. The aim is a detailed research on the infrared absorption spectra of nanodispersed silica modified with urea-formaldehyde polymers with identification of the absorption bands of the spectrum. The method of infrared spectroscopy is used to research spectral characteristics of nanosized silica, urea-formaldehyde polymer and nanodispersed silica modified with urea-formaldehyde polymers in different ratio. It is found that interaction of initial ingredients occurs at the stage of phase formation in solutions in colloidal silica products containing urea-formaldehyde polymers. Organic components are localized on the surface of the globules and in the interglobular space. This result of such interaction is the physical and structural transformation of globular surfaces of silica and new chemical compounds formation. This allows to give to final product a variety of properties required for practical use in many industries.

  12. Substitution effects on the absorption spectra of nitrophenolate isomers.

    Science.gov (United States)

    Wanko, Marius; Houmøller, Jørgen; Støchkel, Kristian; Suhr Kirketerp, Maj-Britt; Petersen, Michael Åxman; Nielsen, Mogens Brøndsted; Nielsen, Steen Brøndsted; Rubio, Angel

    2012-10-05

    Charge-transfer excitations highly depend on the electronic coupling between the donor and acceptor groups. Nitrophenolates are simple examples of charge-transfer systems where the degree of coupling differs between ortho, meta and para isomers. Here we report the absorption spectra of the isolated anions in vacuo to avoid the complications of solvent effects. Gas-phase action spectroscopy was done with two different setups, an electrostatic ion storage ring and an accelerator mass spectrometer. The results are interpreted on the basis of CC2 quantum chemical calculations. We identified absorption maxima at 393, 532, and 399 nm for the para, meta, and ortho isomer, respectively, with the charge-transfer transition into the lowest excited singlet state. In the meta isomer, this π-π* transition is strongly redshifted and its oscillator strength reduced, which is related to the pronounced charge-transfer character, as a consequence of the topology of the conjugated π-system. Each isomer's different charge distribution in the ground state leads to a very different solvent shift, which in acetonitrile is bathochromic for the para and ortho, but hypsochromic for the meta isomer.

  13. Absorption spectra of ammonia near 1 μm

    Science.gov (United States)

    Barton, Emma J.; Polyansky, Oleg L.; Yurchenko, Sergei. N.; Tennyson, Jonathan; Civiš, S.; Ferus, M.; Hargreaves, R.; Ovsyannikov, R. I.; Kyuberis, A. A.; Zobov, N. F.; Béguier, S.; Campargue, A.

    2017-12-01

    An ammonia absorption spectrum recorded at room temperature in the region 8800-10,400 cm-1 is analysed using a variational line list, BYTe, and ground state energies determined using the MARVEL procedure. BYTe is used as a starting point to initialise assignments by combination differences and the method of branches. Assignments are presented for the region 9400-9850 cm-1. 642 lines are assigned to 6 previously unobserved vibrational bands, (2v1 + 2 v42) ±, (2v1 + v31) ± and (v1 + v31 + 2 v42) ±, leading to 428 new energy levels with 208 confirmed by combination differences. A recently calculated purely ab initio NH3 PES is also used to calculate rovibrational energy levels. Comparison with assigned levels shows better agreement between observed and calculated levels than for BYTe for higher vibrational bands.

  14. Anomalies in resonant absorption line profiles of atoms with large hyperfine splitting

    International Nuclear Information System (INIS)

    Parkhomenko, A.I.; Pod'yachev, S.P.; Privalov, T.I.; Shalagin, A.M.

    1997-01-01

    We examine a monochromatic absorption line in the velocity-nonselective excitation of atoms when the components of the hyperfine stricture of the electronic ground states are optically pumped. We show that the absorption lines possess unusual substructures for some values of the hyperfine splitting of the ground state (which exceed the Doppler absorption linewidth severalfold). These substructures in the absorption spectrum are most apparent if the hyperfine structure of the excited electronic state is taken into account. We calculate the absorption spectra of monochromatic light near the D 1 and D 2 lines of atomic rubidium 85,87 Rb. With real hyperfine splitting taken into account, the D 1 and D 2 lines are modeled by 4- and 6-level diagrams, respectively. Finally, we show that atomic rubidium vapor can be successfully used to observe the spectral features experimentally

  15. Optical emission line spectra of Seyfert galaxies and radio galaxies

    International Nuclear Information System (INIS)

    Osterbrock, D.E.

    1978-01-01

    Many radio galaxies have strong emission lines in their optical spectra, similar to the emission lines in the spectra of Seyfert galaxies. The range of ionization extends from [O I] and [N I] through [Ne V] and [Fe VII] to [Fe X]. The emission-line spectra of radio galaxies divide into two types, narrow-line radio galaxies whose spectra are indistinguishable from Seyfert 2 galaxies, and broad-line radio galaxies whose spectra are similar to Seyfert 1 galaxies. However on the average the broad-line radio galaxies have steeper Balmer decrements, stronger [O III] and weaker Fe II emission than the Seyfert 1 galaxies, though at least one Seyfert 1 galaxy not known to be a radio source has a spectrum very similar to typical broad-line radio galaxies. Intermediate-type Seyfert galaxies exist that show various mixtures of the Seyfert 1 and Seyfert 2 properties, and the narrow-line or Seyfert 2 property seems to be strongly correlated with radio emission. (Auth.)

  16. LINE-BY-LINE CALCULATION OF SPECTRA FROM DIATOMIC MOLECULES AND ATOMS ASSUMING A VOIGT LINE PROFILE

    Science.gov (United States)

    Whiting, E. E.

    1994-01-01

    This program predicts the spectra resulting from electronic transitions of diatomic molecules and atoms in local thermodynamic equilibrium. The program produces a spectrum by accounting for the contribution of each rotational and atomic line considered. The integrated intensity of each line is distributed in the spectrum by an approximate Voigt profile. The program can produce spectra for optically thin gases or for cases where simultaneous emission and absorption occurs. In addition, the program can compute the spectrum resulting from the absorption of incident radiation by a column of cold gas or the high-temperature, self-absorbed emission spectrum from a nonisothermal gas. The computed spectrum can be output directly or combined with a slit function and sensitivity calibration to predict the output of a grating spectrograph or a fixed wavelength radiometer. Specifically, the program has the capability to include the following features in any computations: (1) Parallel transitions, in which spin splitting and lambda doubling are ignored (ignoring spin splitting and/or lambda doubling means that the total multiple strength is assumed to reside in a single "effective" line), (2) Perpendicular transitions, in which spin splitting and lambda doubling are ignored, (3) Sigma Pi transitions, in which lambda doubling is ignored, (4) Atomic lines, (5) Option to terminate rotational line calculations when the molecule dissociates due to rotation, (6) Option to include the alternation of line intensities for homonuclear molecules, (7) Use of an approximate Voigt profile for the line shape, and (8) Radiative energy transport in a nonisothermal gas. The output options available in the program are: (1) Tabulation of the spontaneous emission spectrum (i.e., optically thin spectrum) for a 1.0 cm path length, (2) Tabulation of the "true" spectrum, which incorporates spontaneous emission, induced emission, absorption, and externally incident radiation through the equation of

  17. An Inverse Modeling Approach to Estimating Phytoplankton Pigment Concentrations from Phytoplankton Absorption Spectra

    Science.gov (United States)

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

    2011-01-01

    Phytoplankton absorption spectra and High-Performance Liquid Chromatography (HPLC) pigment observations from the Eastern U.S. and global observations from NASA's SeaBASS archive are used in a linear inverse calculation to extract pigment-specific absorption spectra. Using these pigment-specific absorption spectra to reconstruct the phytoplankton absorption spectra results in high correlations at all visible wavelengths (r(sup 2) from 0.83 to 0.98), and linear regressions (slopes ranging from 0.8 to 1.1). Higher correlations (r(sup 2) from 0.75 to 1.00) are obtained in the visible portion of the spectra when the total phytoplankton absorption spectra are unpackaged by multiplying the entire spectra by a factor that sets the total absorption at 675 nm to that expected from absorption spectra reconstruction using measured pigment concentrations and laboratory-derived pigment-specific absorption spectra. The derived pigment-specific absorption spectra were further used with the total phytoplankton absorption spectra in a second linear inverse calculation to estimate the various phytoplankton HPLC pigments. A comparison between the estimated and measured pigment concentrations for the 18 pigment fields showed good correlations (r(sup 2) greater than 0.5) for 7 pigments and very good correlations (r(sup 2) greater than 0.7) for chlorophyll a and fucoxanthin. Higher correlations result when the analysis is carried out at more local geographic scales. The ability to estimate phytoplankton pigments using pigment-specific absorption spectra is critical for using hyperspectral inverse models to retrieve phytoplankton pigment concentrations and other Inherent Optical Properties (IOPs) from passive remote sensing observations.

  18. Infrared absorption spectra of various doping states in cuprate superconductors

    International Nuclear Information System (INIS)

    Yonemitsu, K.; Bishop, A.R.; Lorenzana, J.

    1992-01-01

    Doping states in a two-dimensional three-band extended Peierls-Hubbard model was investigated within inhomogeneous Hartree-Fock and random phase approximation. They are very sensitive to small changes of interaction parameters and their distinct vibrational and optical absorption spectra can be used to identify different doping states. For electronic parameters relevant to cuprate superconductors, as intersite electron-phonon interaction strength increases, the doping state changes from a Zhang-Rice state to a covalent molecular singlet state accompanied by local quenching of the Cu magnetic moment and large local lattice distortion in an otherwise undistorted antiferromagnetic background. In a region where both intersite electron-phonon interaction and on-site electron-electron repulsion are large, we obtain new stable global phases including a bond-order-wave state and a mixed state of spin-Peierls bonds and antiferromagnetic Cu spins, as well as many metastable states. Doping in the bond-order-wave region induces separation of spin and charge. 9 refs

  19. Absorption spectra of superconducting qubits driven by bichromatic microwave fields

    Science.gov (United States)

    Pan, Jiazheng; Jooya, Hossein Z.; Sun, Guozhu; Fan, Yunyi; Wu, Peiheng; Telnov, Dmitry A.; Chu, Shih-I.; Han, Siyuan

    2017-11-01

    We report experimental observation of two distinct quantum interference patterns in the absorption spectra when a transmon superconducting qubit is subjected to a bichromatic microwave field with the same Rabi frequencies. Within the two-mode Floquet formalism with no dissipation processes, we propose a graph-theoretical representation to model the interaction Hamiltonian for each of these observations. This theoretical framework provides a clear visual representation of various underlying physical processes in a systematic way beyond rotating-wave approximation. The presented approach is valuable to gain insights into the behavior of multichromatic field driven quantum two-level systems, such as two-level atoms and superconducting qubits. Each of the observed interference patterns is represented by appropriate graph products on the proposed color-weighted graphs. The underlying mechanisms and the characteristic features of the observed fine structures are identified by the transitions between the graph vertices, which represent the doubly dressed states of the system. The good agreement between the numerical simulation and experimental data confirms the validity of the theoretical method. Such multiphoton interference may be used in manipulating the quantum states and/or generate nonclassical microwave photons.

  20. Discovery of Variable Hydrogen Balmer Absorption Lines with Inverse Decrement in PG 1411+442

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Xi-Heng; Pan, Xiang; Zhang, Shao-Hua; Sun, Lu-Ming; Ji, Tuo; Liu, Bo; Zhou, Hong-Yan [Polar Research Institute of China, Jinqiao Road 451, Shanghai 200136 (China); Wang, Jian-Guo [Yunnan Observatories, Chinese Academy of Sciences, Kunming, Yunnan 650011 (China); Yang, Chen-Wei; Jiang, Ning, E-mail: zhouhongyan@pric.org.cn, E-mail: shixiheng@pric.org.cn [Key Laboratory for Research in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China, Chinese Academy of Sciences, Hefei, Anhui 230026 (China)

    2017-07-01

    We present new optical spectra of the well-known broad absorption line (BAL) quasar PG 1411+442, using the DBSP spectrograph at the Palomar 200 inch telescope in 2014 and 2017 and the YFOSC spectrograph at the Lijiang 2.4 m telescope in 2015. A blueshifted narrow absorption line system is clearly revealed in 2014 and 2015 consisting of hydrogen Balmer series and metastable He i lines. The velocity of these lines is similar to the centroid velocity of the UV BALs, suggesting that both originate from the outflow. The Balmer lines vary significantly between the two observations and vanished in 2017. They were also absent in the archived spectra obtained before 2001. The variation is thought to be driven by photoionization change. Besides, the absorption lines show inversed Balmer decrement, i.e., the apparent optical depths of higher-order Balmer absorption lines are larger than those of lower-order lines, which is inconsistent with the oscillator strengths of the transitions. We suggest that such anomalous line ratios can be naturally explained by the thermal structure of a background accretion disk, which allows the obscured part of the disk to contribute differently to the continuum flux at different wavelengths. High-resolution spectroscopic and photometric monitoring would be very useful to probe the structure of the accretion disk as well as the geometry and physical conditions of the outflow.

  1. Discovery of Variable Hydrogen Balmer Absorption Lines with Inverse Decrement in PG 1411+442

    Science.gov (United States)

    Shi, Xi-Heng; Pan, Xiang; Zhang, Shao-Hua; Sun, Lu-Ming; Wang, Jian-Guo; Ji, Tuo; Yang, Chen-Wei; Liu, Bo; Jiang, Ning; Zhou, Hong-Yan

    2017-07-01

    We present new optical spectra of the well-known broad absorption line (BAL) quasar PG 1411+442, using the DBSP spectrograph at the Palomar 200 inch telescope in 2014 and 2017 and the YFOSC spectrograph at the Lijiang 2.4 m telescope in 2015. A blueshifted narrow absorption line system is clearly revealed in 2014 and 2015 consisting of hydrogen Balmer series and metastable He I lines. The velocity of these lines is similar to the centroid velocity of the UV BALs, suggesting that both originate from the outflow. The Balmer lines vary significantly between the two observations and vanished in 2017. They were also absent in the archived spectra obtained before 2001. The variation is thought to be driven by photoionization change. Besides, the absorption lines show inversed Balmer decrement, I.e., the apparent optical depths of higher-order Balmer absorption lines are larger than those of lower-order lines, which is inconsistent with the oscillator strengths of the transitions. We suggest that such anomalous line ratios can be naturally explained by the thermal structure of a background accretion disk, which allows the obscured part of the disk to contribute differently to the continuum flux at different wavelengths. High-resolution spectroscopic and photometric monitoring would be very useful to probe the structure of the accretion disk as well as the geometry and physical conditions of the outflow.

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

    International Nuclear Information System (INIS)

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

    1975-01-01

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

  3. Recommendations for the presentation of infrared absorption spectra in data collections condensed phases

    CERN Document Server

    Becker, E D

    2013-01-01

    Recommendations for the Presentation of Infrared Absorption Spectra in Data Collections-A. Condensed Phases presents the recommendations related to the infrared spectra of condensed phase materials that are proposed for permanent retention in data collections. These recommendations are based on two reports published by the Coblentz Society. This book emphasizes the three levels of quality evaluation for infrared spectra as designated by the Coblentz Society, including critically defined physical data, research quality analytical spectra, and approved analytical spectra. This text discusses the

  4. Computer simulation of molecular absorption spectra for asymmetric top molecules

    International Nuclear Information System (INIS)

    Bende, A.; Tosa, V.; Cosma, V.

    2001-01-01

    The effective Hamiltonian formalism has been used to develop a model for infrared multiple-photon absorption (IRMPA) process in asymmetric top molecules. Assuming a collisionless regime, the interaction between the molecule and laser field can be described by the time-dependent Schroedinger equation. By using the rotating wave approximation and Laplace transformation, the time-dependent problem reduces to a time-independent eigen problem for an effective Hamiltonian which can be solved only numerically for a real vibrational-rotational structure of polyatomic molecule. The vibrational-rotational structure is assumed to be an anharmonic oscillator coupled to an asymmetric rigid rotor. The main assumptions taken into account for this model are the following: (1) the excitation is coherent, i.e. the collision (if present during the laser pulse) does not influence the excitation; (2) the excitation starts from the ground state and is near resonant to a normal mode, thus, the rotating wave approximation can be applied; (3) after absorbing N photons the vibrational energy of the excited mode leak into a quasicontinuum; (4) the thermal population of the ground state is given by the Maxwell-Boltzmann distribution law. The energy levels of the asymmetric top molecules cannot be represented by an explicit formula analogous to that for the symmetric top, according to quantum mechanics, but we can consider it a deviation from the prolate or oblate case of the symmetric top, and we can find in the same manner the selection rules of the asymmetric case using the selection rules for the symmetric case. The infrared bands of asymmetric top molecules are not resolved, but if the dispersion used is not too small, so that the envelopes of the bands can be distinguished from simple maxima, it is possible to draw conclusions as to the type of the bands. In this case, the simulation of the absorption spectra can give us some important information about the types of these bands. In

  5. A study of luminescence and absorption spectra of GaP

    International Nuclear Information System (INIS)

    Mansour, H.M.M.; Abdel Wahab, S.M.

    1994-08-01

    Experimental luminescence and absorption spectra of GaP at room temperature are presented. A theoretical analysis has been performed on the luminescence and absorption spectra in GaP. The experimental data are in good agreement with the theoretical results. (author). 18 refs, 8 figs

  6. Error reduction in retrievals of atmospheric species from symmetrically measured lidar sounding absorption spectra.

    Science.gov (United States)

    Chen, Jeffrey R; Numata, Kenji; Wu, Stewart T

    2014-10-20

    We report new methods for retrieving atmospheric constituents from symmetrically-measured lidar-sounding absorption spectra. The forward model accounts for laser line-center frequency noise and broadened line-shape, and is essentially linearized by linking estimated optical-depths to the mixing ratios. Errors from the spectral distortion and laser frequency drift are substantially reduced by averaging optical-depths at each pair of symmetric wavelength channels. Retrieval errors from measurement noise and model bias are analyzed parametrically and numerically for multiple atmospheric layers, to provide deeper insight. Errors from surface height and reflectance variations are reduced to tolerable levels by "averaging before log" with pulse-by-pulse ranging knowledge incorporated.

  7. [Study on UV-Vis absorption spectra and fluorescence emission spectra of sixteen tetra-substituted metallophthalocyanine complexes].

    Science.gov (United States)

    Huang, Zi-yang; Huang, Jian-dong; Chen, Nai-sheng; Huang, Jin-ling

    2009-05-01

    The UV-Visible absorption spectra and the fluorescence emission spectra of sixteen tetra-substituted metallo-phthalocyanine complexes {R4 PcM, where R = 2-[4-(2-sulfonic ethyl) piperazin-1-] ethoxyl (SPEO--), 2-(piperidin-1-yl) ethoxyl (PEO--); substitution position at alpha-position and beta-position of phthalocyanine ring; M = Zn(II), Ni(II), Co(II) and Cu(II)} were measured. The influence of different central ion, substituted group and its position, as well as different solvent on the Q-band of phthalocyanine complex in its UV-Vis absorption spectra was investigated. The influence of different central ion, substituted group and its position on the fluorescence emission spectra was discussed. Some properties of the UV-Vis absorption spectra such as the maximum absorption wavelength (lamdamax ) of Q-band and its molar extinction coefficient (epsilon), and those of the fluorescence emission spectra such as fluorescence quantum yield (phiF), fluorescence lifetime (r) and excited state energy (Es) were studied. The results showed that the lamdamax of Qband of all complexes were located at 681-718 nm, which had a distinct red shift in contrast with unsubstituted metallophthalocyanines (669-671 nm). All complexes of R4 PcM possessed a very high molar extinction coefficient up to 10(5) L x mol(-1) x cm(-1). And the UV-Vis absorption spectra and the fluorescence emission spectra of all complexes exhibited mirror shape concurrently. Two beta-substituted zinc phthalocyanine complexes with formula beta-(SPEO)4PcZn and beta-(PEO)4PcZn possessed very high molar extinction coefficient, fluorescence quantum yield and fluorescence lifetime specially. Therefore, it is hoped that these two would be developing to be new photosensitizers for photodynamic therapy (PDT)and photodynamic diagnosis (PDD).

  8. Linear optical absorption spectra of mesoscopic structures in intense THz fields: Free-particle properties

    DEFF Research Database (Denmark)

    Johnsen, Kristinn; Jauho, Antti-Pekka

    1998-01-01

    We theoretically study the effect of THz radiation on the linear optical absorption spectra of semiconductor structures. A general theoretical framework, based on nonequilibrium Green functions, is formulated and applied to the calculation of linear optical absorption spectrum for several...... stable steps appear in the absorption spectrum when conditions for dynamical localization are met. [S0163-1829(95)03412-2]....

  9. LIME: Semiautomated line measurement and identification from stellar spectra

    Science.gov (United States)

    Sahin, T.

    2017-09-01

    We present LIME (Line Measurements from ECHELLE Spectra), an IDL-based code, as a powerful tool for semiautomated stellar line measurement and identification. Interactively selected line positions (i.e. wavelengths) are compared with a master line list of the user's selections. Each unknown line that the user interactively chooses is displayed with potential identifications provided by the code in the vicinity of the selected line. The best identification is evaluated on the basis of several criteria (e.g., atomic/molecular line information, wavelength displacement, and theoretical equivalent width for solar atmospheric values). We examined the identifications by LIME in the spectra of post-red supergiant star HD 179821 over a range of signal-to-noise values and wavelength ranges. We found that the results obtained by LIME show virtually complete agreement with the manual identifications for which the conventional and also tedious approach is to use a revised multiplet table as an initial guide and perform a systematic search that makes use of the lower excitation potential and gf-values. Comparison to previous identifications for HD 179821 in the literature revealed not only lines that were unmeasurable and/or blended but also misidentifications. While a manual identification process takes a relatively longer time to be accomplished by an experienced spectroscopist, LIME can provide a rapid extraction of line information in a few hours with moderate user interaction.

  10. Infrared spectra of peculiar emission-line stars

    International Nuclear Information System (INIS)

    Andrillat, Yvette; Houziaux, Leo

    1975-01-01

    230A/mm spectra of HD51585, V1016Cyg, HBV475 and XXOph between 8,000 and 11,000A are described. Important spectral variations have been noted between 1974 and 1975. Satisfactory identifications cannot be proposed for lines at 9,180 and 9,204A [fr

  11. Low-Cost Elimination of Plasma Lines in Raman Spectra.

    Science.gov (United States)

    Behlow, Herbert W., Jr.; Petersen, John D.

    1985-01-01

    Describes a low-cost ($120) device which eliminates plasma lines in Raman spectra. The device consists of two prisms and two mirrors which are held in a symmetrical relationship to one another so that a particular position will allow only one wavelength to pass through on a given axis. (JN)

  12. Radio line and continuum observations of quasar-galaxy pairs and the origin of low reshift quasar absorption line systems

    Science.gov (United States)

    Carilli, C. L.; Vangorkom, J. H.; Hauxthausen, E. M.; Stocke, J. T.; Salzer, J.

    1990-01-01

    There are a number of known quasars for which our line of sight to the high redshift quasar passes within a few Holmberg radii of a low redshift galaxy. In a few of these cases, spectra of the quasar reveal absorption by gas associated with the low redshift galaxy. A number of these pairs imply absorption by gas which lies well outside the optical disk of the associated galaxy, leading to models of galaxies with 'halos' or 'disks' of gas extending to large radii. The authors present observations of 4 such pairs. In three of the four cases, they find that the associated galaxy is highly disturbed, typically due to a gravitational interaction with a companion galaxy, while in the fourth case the absorption can be explained by clouds in the optical disk of the associated galaxy. They are led to an alternative hypothesis concerning the origin of the low redshift absorption line systems: the absorption is by gas clouds which have been gravitationally stripped from the associated galaxy. These galaxies are rapidly evolving, and should not be used as examples of absorption by clouds in halos of field spirals. The authors conclude by considering the role extended gas in interacting systems plays in the origin of higher redshift quasar absorption line systems.

  13. PG 1700 + 518 - a low-redshift, broad absorption line QSO

    International Nuclear Information System (INIS)

    Pettini, M.; Boksenberg, A.

    1985-01-01

    The first high-resolution optical spectra and lower resolution UV spectra of PG 1700 + 518, the only known broad-absorption-line (BAL) QSO at low emission redshift (0.288) are presented. The optical data were obtained with the Isaac Newton Telescope on the island of La Palma and the UV data with the International Ultraviolet Explorer satellite. The outstanding feature of the optical spectrum is a strong, broad Mg II absorption trough, detached from the Mg II emission line and indicative of ejection velocities of between 7000 and 18,000 km/s. Also detected were narrow (FWHM = 350 km/s) Mg II absorption lines at absolute z = 0.2698, which are probably related to the mass ejection phenomenon. It is concluded that the emission-line spectrum is similar to that of other low-redshift QSOs although there are some obvious differences from typical BAL QSOs, most notably in the unusually low level of ionization of both emission-line and broad absorption line gas. 21 references

  14. ExoCross: Spectra from molecular line lists

    Science.gov (United States)

    Yurchenko, Sergei N.; Al-Refaie, Ahmed; Tennyson, Jonathan

    2018-03-01

    ExoCross generates spectra and thermodynamic properties from molecular line lists in ExoMol, HITRAN, or several other formats. The code is parallelized and also shows a high degree of vectorization; it works with line profiles such as Doppler, Lorentzian and Voigt and supports several broadening schemes. ExoCross is also capable of working with the recently proposed method of super-lines. It supports calculations of lifetimes, cooling functions, specific heats and other properties. ExoCross converts between different formats, such as HITRAN, ExoMol and Phoenix, and simulates non-LTE spectra using a simple two-temperature approach. Different electronic, vibronic or vibrational bands can be simulated separately using an efficient filtering scheme based on the quantum numbers.

  15. Inelastic electron scattering spectroscopy: a comparison of absorption and emission spectra

    International Nuclear Information System (INIS)

    Schnatterly, S.E.

    1984-01-01

    The operation of a high energy inelastic scattering spectrometer is briefly described. Measured absorption and emission spectra are fit to parameters in recently described models for insulators. Implications for model validity are discussed

  16. Absorption spectra of ammonia near 1 mu m

    Czech Academy of Sciences Publication Activity Database

    Barton, E. J.; Polyansky, O. L.; Yurchenko, S. N.; Tennyson, J.; Civiš, Svatopluk; Ferus, Martin; Hargreaves, R.; Ovsyannikov, R. I.; Kyuberis, A. A.; Zobov, N. F.; Béguier, S.; Campargue, A.

    2017-01-01

    Roč. 203, DEC 2017 (2017), s. 392-397 ISSN 0022-4073 EU Projects: European Commission(XE) 267219 - EXOMOL Grant - others:RFBR(RU) 16-32-00244 Institutional support: RVO:61388955 Keywords : room temperature * ammonia * absorption intensities * FTIR spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 2.419, year: 2016

  17. Optical absorption spectra of linear and cyclic thiophenes--selection rules manifestation

    International Nuclear Information System (INIS)

    Bednarz, Mariusz; Reineker, Peter; Mena-Osteritz, Elena; Baeuerle, Peter

    2004-01-01

    We theoretically study the size-dependent relation between absorption spectra of thiophene-based oligomers and the corresponding cyclothiophenes. In our approach based on a Frenkel exciton Hamiltonian, we demonstrate that the geometry and selection rules determine the observed relations between the spectra

  18. Absorption Spectra Of Rbcl:Yb Rbbr:Yb And Rbi:Yb Crystals ...

    African Journals Online (AJOL)

    Single crystals of rubidium chloride, bromide and iodide were doped with substitutional divalent ytterbium, Yb ions, by heating them in ytterbium atmosphere. The absorption spectra of the Yb doped crystals were measured at room and liquid nitrogen temperatures. The spectra were found to consist of intense broad ...

  19. Invisible structures in the X-ray absorption spectra of actinides

    NARCIS (Netherlands)

    Kvashnina, Kristina O.; De Groot, Frank M F

    The X-ray absorption spectra of actinides are discussed with an emphasis on the fundamental effects that influence their spectral shape, including atomic multiplet theory, charge transfer theory and crystal field theory. Many actinide spectra consist of a single peak and it is shown that the use of

  20. SPECTROPHOTOMETRY OF HEMOGLOBIN - ABSORPTION-SPECTRA OF RAT OXYHEMOGLOBIN, DEOXYHEMOGLOBIN, CARBOXYHEMOGLOBIN, AND METHEMOGLOBIN

    NARCIS (Netherlands)

    ZIJLSTRA, WG; BUURSMA, A; FALKE, HE; CATSBURG, JF

    The absorptivity at 540 nm of methemoglobincyanide from rat blood was determined on the basis of iron and found to be equal to the established value for human methemoglobincyanide (11,01/mmol/cm). On this basis the absorption spectra of the common derivatives were determined for rat hemoglobin.

  1. Spectrophotometry of hemoglobin : Absorption spectra of bovine oxyhemoglobin, deoxyhemoglobin, carboxyhemoglobin, and methemoglobin

    NARCIS (Netherlands)

    Zijlstra, WG; Buursma, A

    1997-01-01

    The absorptivity at 540 nm of bovine hemiglobincyanide (cyanmethemoglobin) was determined on the basis of the iron content and found to be equal to the established value for human hemiglobincyanide (11.0 L . mmol(-1).cm(-1)). On this basis the absorption spectra of the common derivatives were

  2. Electronic and oscillation absorption spectra of blood plamsa at surgical diseases of thyroid gland

    Science.gov (United States)

    Guminetskiy, S. G.; Motrich, A. V.; Poliansky, I. Y.; Hyrla, Ya. V.

    2012-01-01

    The results of investigating the absorption spectra of blood plasma in the visible and infrared parts of spectra obtained using the techniques of spherical photometer and spectrophotometric complex "Specord IR75" are presented. The possibility of using these spectra for diagnoses the cases of diffuse toxic goiter and nodular goiter and control of treatment process in postsurgical period in the cases of thyroid gland surgery is estimated.

  3. Searching for Variability of NV Intrinsic Narrow Absorption Line Systems

    Science.gov (United States)

    Rodruck, Michael; Charlton, Jane; Ganguly, Rajib

    2018-01-01

    The majority of quasar absorption line systems with NV detected are found within the associated region (within 5000 km/s of the quasar redshift) and many/most are believed to be related to the quasar accretion disk wind or outflows. The most definite evidence that these NV absorbers are "intrinsic" is partial covering of the quasar continuum source and/or broad line region. Over 75 quasars containing NV narrow absorption lines have observations obtained at different times with the Keck/HIRES and the VLT/UVES spectrographs at high resolution. The interval between these observations range from months to a decade in the quasar rest frame. While variability is common for intrinsic broad and mini-broad absorption lines, intrinsic narrow absorption lines have been found to be less likely to vary, though systematic studies with large, high quality datasets have been limited. The variability timescales are useful for deriving gas densities and thus the distances from the central engines. This is important in mapping the quasar surroundings, understanding the accretion disk wind mechanism, and assessing the effect the wind has on the galaxy surroundings. We report on the results of a systematic study of variability of NV NALs, exploiting the overlap of targets for observations in the archives of Keck and VLT, and discuss the consequences for interpretation of the origin of intrinsic narrow absorption lines.

  4. The Associated Absorption Features in Quasar Spectra of the Sloan Digital Sky Survey. I. Mg II Absorption Doublets

    Science.gov (United States)

    Chen, Zhi-Fu; Huang, Wei-Rong; Pang, Ting-Ting; Huang, Hong-Yan; Pan, Da-Sheng; Yao, Min; Nong, Wei-Jing; Lu, Mei-Mei

    2018-03-01

    Using the SDSS spectra of quasars included in the DR7Q or DR12Q catalogs, we search for Mg II λλ2796, 2803 narrow absorption doublets in the spectra data around Mg II λ2798 emission lines. We obtain 17,316 Mg II doublets, within the redshift range of 0.3299 ≤ z abs ≤ 2.5663. We find that a velocity offset of υ r 6000 km s‑1. If associated Mg II absorbers are defined by υ r present at least one associated Mg II system with {W}{{r}}λ 2796≥slant 0.2 \\mathringA . The fraction of associated Mg II systems with high-velocity outflows correlates with the average luminosities of their central quasars, indicating a relationship between outflows and the quasar feedback power. The υ r distribution of the outflow Mg II absorbers is peaked at 1023 km s‑1, which is smaller than the corresponding value of the outflow C IV absorbers. The redshift number density evolution of absorbers (dn/dz) limited by υ r > ‑3000 km s‑1 differs from that of absorbers constrained by υ r > 2000 km s‑1. Absorbers limited by υ r > 2000 km s‑1 and higher values exhibit profiles similar to dn/dz. In addition, the dn/dz is smaller when absorbers are constrained with larger υ r . The distributions of equivalent widths, and the ratio of {W}rλ 2796/{W}rλ 2803, are the same for associated and intervening systems, and independent of quasar luminosity.

  5. Infrared absorption spectra of human malignant tumor tissues

    Science.gov (United States)

    Skornyakov, I. V.; Tolstorozhev, G. B.; Butra, V. A.

    2008-05-01

    We used infrared spectroscopy methods to study the molecular structure of tissues from human organs removed during surgery. The IR spectra of the surgical material from breast, thyroid, and lung are compared with data from histological examination. We show that in malignant neoplasms, a change occurs in the hydrogen bonds of protein macromolecules found in the tissue of the studied organs. We identify the spectral signs of malignant pathology.

  6. Line by Line Analysis of Carbon Dioxide Absorption for Predicting Global Warming

    Science.gov (United States)

    Smith, D. C.

    2010-12-01

    The anthropologic cause of global warming rests on the impact of CO2 on the green house effect. Previous derivations of the increase in the CO2 Forcing Function caused by doubling of atmospheric CO2 from 320 ppm to 640 ppm reported a value of 4 W/M2( Ramananathan,V,et al, J.of Geophysical Research Vol 84, C8,p4949, Aug.1979) This value leads to a calculated temperature rise of 1 deg.K (Charney,J. et al,”Carbon Dioxide and Climate: A Scientific Assessment”, National Academy of Science, Washington D.C., 1979). This increase in global temperature leads to an increase in water vapor if it is assumed that the relative humidity is constant. This ampflication leads to a calculated temperature rise of an additional 2 deg.K. Different arguments as to the effects of the earth’s albido change, clouds, and the oceans also impact the earths global warming with predictions of total temperature rise of as high as 6 deg.K { IPCC,2007 Summary for Policymakers. In: Climate Change 2007: The Physical Sciences Basis. Contributions of Working Group 1 to the Fourth Assessment Report of the IPCC [ Solomon,S,D. et al (eds)] Cambridge University Press, NY,USA}. Regardless of the other effects, the only way that man can be held responsible for global warming is by CO2 emissions and the resulting increase in the Forcing Function. This paper challenges the magnitude of the 4 W/M2 Forcing Function. The earth radiates in the 4 to 30 micron wavelength range. CO2 has absorption bands in the 4, 10, and 15 micron wavelengths (Hertzberg G. Molecular Spectra & Molecular Structure,Norstrand Co.,1960). McClatchey has tabulated the line stengths for all CO2 transitions and they are used to calculate the atmospheric absorption (McClatchey,R, et al “AFCRL Atmospheric Absorption Line Parameter Compilation”,AFCRL-TR-0096,1973). Detailed calculations of the CO2 line absorption in the 8 to 12 micron atmospheric window shows an increase of 0.3 W/M2 for CO2 doubling. The increase in absorbed fluence in

  7. Kennard-Stepanov relation connecting absorption and emission spectra in an atomic gas.

    Science.gov (United States)

    Moroshkin, Peter; Weller, Lars; Sass, Anne; Klaers, Jan; Weitz, Martin

    2014-08-08

    The Kennard-Stepanov relation describes a thermodynamic, Boltzmann-type scaling between the absorption and emission spectral profiles of an absorber, which applies in many liquid state dye solutions as well as in semiconductor systems. Here we examine absorption and emission spectra of rubidium atoms in a dense argon buffer gas environment. We demonstrate that the Kennard-Stepanov relation between absorption and emission spectra is well fulfilled in the collisionally broadened atomic gas system. Our experimental findings are supported by a simple theoretical model.

  8. Line broadening in the neutral and ionized mercury spectra

    Science.gov (United States)

    Gavrilov, M.; Skočić, M.; Burger, M.; Bukvić, S.; Djeniže, S.

    2012-10-01

    The neutral, singly, doubly and triply ionized mercury (Hg I-IV, respectively) spectral line shapes and line center positions have been investigated in the laboratory helium plasma at electron densities ranging between 9.3 × 1022 m-3 and 1.93 × 1023 m-3 and electron temperatures around 19,500 K, both interesting for astrophysics. The mercury (natural isotope composition) atoms were sputtered from the cylindrical amalgamated gold plates located in the homogenous part of the pulsed helium discharge operating at a pressure of 665 Pa in a flowing regime. The mercury spectral line profiles were recorded using the McPherson model 209 spectrograph and the Andor ICCD camera as the detection system. This research presents Stark broadening parameters, the width (W) and the shift (d), of one Hg I, 19 Hg II, 6 Hg III and 4 Hg IV lines, not investigated so far. Our experimental W values were compared with the data calculated applying various approaches. The shape and intensity of astrophysically important 398.4 nm Hg II spectral line was discussed taking into account the isotope shift, hyperfine structure and Penning effects. At the mentioned plasma parameters the Stark broadening is found to be a main line broadening mechanism of the lines (λ > 200 nm) in the Hg I-IV spectra.

  9. The spatial and kinematic structure of QSO metal-line absorption systems

    Science.gov (United States)

    Lanzetta, Kenneth M.

    1992-01-01

    Recent attempts to infer the spatial and kinematic distributions of the material responsible for absorption lines observed in the spectra of background QSOs are presented. Current models of the absorbing regions are compared, and initial observational results are described. This research is expected to lead eventually to a detailed picture of the extended gaseous halo regions of galaxies at early evolutionary stages and to an understanding of the physical processes at work in these halos.

  10. In vivo absorption spectra of the two stable states of the Euglena photoreceptor photocycle.

    Science.gov (United States)

    Barsanti, Laura; Coltelli, Primo; Evangelista, Valtere; Passarelli, Vincenzo; Frassanito, Anna Maria; Vesentini, Nicoletta; Santoro, Fabrizio; Gualtieri, Paolo

    2009-01-01

    Euglena gracilis possesses a simple but sophisticated light detecting system, consisting of an eyespot formed by carotenoids globules and a photoreceptor. The photoreceptor of Euglena is characterized by optical bistability, with two stable states. In order to provide important and discriminating information on the series of structural changes that Euglena photoreceptive protein(s) undergoes inside the photoreceptor in response to light, we measured the in vivo absorption spectra of the two stable states A and B of photoreceptor photocycle. Data were collected using two different devices, i.e. a microspectrophotometer and a digital microscope. Our results show that the photocycle and the absorption spectra of the photoreceptor possess strong spectroscopic similarities with a rhodopsin-like protein. Moreover, the analysis of the absorption spectra of the two stable states of the photoreceptor and the absorption spectrum of the eyespot suggests an intriguing hypothesis for the orientation of microalgae toward light.

  11. Faraday effect and λ-modulation absorption spectra of GaP

    International Nuclear Information System (INIS)

    Petkova, P N; Dimov, T N; Iliev, I A

    2007-01-01

    There are presented the absorption optical spectra of GaP measured by λ-modulation method at room temperature in the spectral region from 505 nm to 700 nm. It is not possible even by λ-modulation to be registered at room temperature the wave bands due to the exciton-phonon interaction. The absorption spectra of GaP carried out by a λ-modulation can be separated exactly in the spectral parts as follows: the transmittance region where the absorption is too slightly expressed; the region determined by the phonon-assisted indirect transitions; the region of the interband absorption. The purpose of Faraday rotation measurements is to establish the influence of the exciton-phonon interaction on the magneto-optical effect. The magneto-optical effect has been investigated by a φ-modulation. The spectral dependence of dn/dλ in the transmittance region is determined by the φ-modulated spectra

  12. Carbon dioxide laser absorption spectra of toxic industrial compounds

    International Nuclear Information System (INIS)

    Loper, G.L.; Sasaki, G.R.; Stamps, M.A.

    1982-01-01

    CO 2 laser absorption cross-section data are reported for acrolein, styrene, ethyl acrylate, trichloroethylene, vinyl bromide, and vinylidene chloride. These data indicate that sub parts per billion level, interference-free detection limits should be possible for these compounds by the CO 2 laser photoacoustic technique. Photoacoustic detectabilities below 40 ppb should be possible for these compounds in the presence of ambient air concentrations of water vapor and other anticipated interferences. These compounds are also found not to be important inerference in the detection of toxic hydrazine-based rocket fuels by CO 2 laser spectroscopic techniques

  13. The low-ion QSO absorption-line systems

    International Nuclear Information System (INIS)

    Lanzetta, K.M.

    1988-01-01

    Various techniques are used to investigate the class of QSO absorption-line systems that exhibit low-ion absorption lines. Four separate investigations are conducted as follows: Spectroscopy of 32 QSOs at red wavelengths is presented and used to investigate intermediate-redshift MgII absorption. A total of 22 Mg II doublets are detected, from which properties of the Mg II absorbers are derived. Marginal evidence for intrinsic evolution of the number density of the Mg II absorbers with redshift is found. The data are combined with previous observations of C IV and C II seen in the same QSOs at blue wavelengths, and the properties of Mg II- and C IV-selected systems are compared. A sample is constructed of 129 QSOs for which are available published data suitable for detecting absorption-line systems that are optically thick to Lyman continuum radiation. A total of 53 such Lyman-limit systems are found, from which properties of the Lyman-limit systems are derived. It is found that the rate of incidence of the systems does not strongly evolved with redshift. This result is contrasted with the evolution found previously for systems selected on the basis of Mg II absorption. Spectroscopy at red wavelengths of eight QSOs with known damped Lyα absorption systems is presented. Spectroscopic and spectrophotometric observations aimed at detecting molecular hydrogen and dust in the z = 2.796 damped Lyα absorber toward Q1337 + 113 are presented

  14. Terahertz absorption spectra of commonly used antimalarial drugs

    Science.gov (United States)

    Bawuah, Prince; Zeitler, J. Axel; Ketolainen, Jarkko; Peiponen, Kai-Erik

    2018-03-01

    Terahertz (THz) spectra from the pure forms [i.e. the active pharmaceutical ingredients (APIs)] of four commonly used antimalarial drugs are reported. The well-defined spectral fingerprints obtained for these APIs in the spectral range of 0.1 THz-3 THz show the sensitivity of the THz time-domain spectroscopic (THz-TDS) method for screening antimalarial drugs. For identification purpose, two commercially available antimalarial tablets were detected. Clear spectral fingerprints of the APIs in the antimalarial tablets were obtained even amidst the several types of excipients present in the tablets. This observation further proves the high sensitivity of the THz techniques in tracking the presence or absence of API in a pharmaceutical tablet. We envisage that the spectral data obtained for these drugs can contribute to a spectroscopic database in the far infrared spectral region and hence support the modelling of THz sensing to differentiate between genuine and counterfeit antimalarial tablets.

  15. Linewidths in excitonic absorption spectra of cuprous oxide

    Science.gov (United States)

    Schweiner, Frank; Main, Jörg; Wunner, Günter

    2016-02-01

    We present a theoretical calculation of the absorption spectrum of cuprous oxide (Cu2O ) based on the general theory developed by Y. Toyozawa. An inclusion not only of acoustic phonons but also of optical phonons and of specific properties of the excitons in Cu2O like the central-cell corrections for the 1 S exciton allows us to calculate the experimentally observed linewidths in experiments by T. Kazimierczuk et al. [T. Kazimierczuk, D. Fröhlich, S. Scheel, H. Stolz, and M. Bayer, Nature (London) 514, 343 (2014), 10.1038/nature13832] within the same order of magnitude, which demonstrates a clear improvement in comparison to earlier work on this topic. We also discuss a variety of further effects, which explain the still observable discrepancy between theory and experiment but can hardly be included in theoretical calculations.

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

    DEFF Research Database (Denmark)

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

    2013-01-01

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

  17. ROSAT PSPC spectra of X-ray selected narrow emission line galaxies

    Science.gov (United States)

    Colmenero, E. Romero; Carrera, F. J.; Branduardi-Raymont, G.; Mittaz, J. P. D.; McHardy, I. M.; Jones, L. R.

    1996-01-01

    The Rosat Position Sensitive Proportional Counter (PSPC) spectra of a sample of 35 X-ray selected Narrow Emission Line Galaxies (NELGs) are presented. Of these 35 objects, 16 are from the Rosat International X-ray Optical Survey (RIXOS) and the remaining 19 were discovered during the optical identification of Rosat U.K. deep survey sources. A power law model with low energy absorption set at the Galactic value is found to be a good fit for all sources. The results indicate that the spectral slope of NELGs is flatter than that of active galactic nuclei.

  18. Identification of Metal Absorption Lines on Quasar Spectra of SDSS ...

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... Cai-Juan Pan1 Cheng-Yu Su2 Mu-Sheng Li3 Wei-Rong Huang3. Department of Physics and Telecommunication Engineering of Baise University, Baise 533000, China. Guangdong University of Technology, Guangzhou 510006, China. Centre for Astrophysics, Guangzhou University, Guangzhou 510006, ...

  19. High-resolution absorption coefficient and refractive index spectra of common pollutant gases at millimeter and THz wavelengths

    Science.gov (United States)

    Almoayed, Nawaf N.; Piyade, Baris C.; Afsar, Mohammed N.

    2007-09-01

    Dispersive Fourier Transform Spectroscopy (DFTS) provides us with a very precise method of measuring the absorption and refractive index spectra of common pollutant gases. This paper presents the rotational transition lines of Sulfur Dioxide and Carbon Monoxide gas as a function of varying pressure using DFTS for the very first time as a combined study. The relationship between the variation of the pressure and the change in the absorption spectrum is examined and discussed in detail. Sulfur Dioxide and Carbon Monoxide gases are highly toxic, pollutant gases that are major contributors to global pollution and can potentially be used as a chemical threat. The relationship between pressure and rotational transmission lines is discussed in detail in the frequency range of 0.3 THz - 0.9 THz. These findings are crucial in characterizing these gases as well as identifying them in a blind test.

  20. Estimation of damped oscillation associated spectra from ultrafast transient absorption spectra

    NARCIS (Netherlands)

    van Stokkum, Ivo; Jumper, Chanelle C.; Snellenburg, J.; Scholes, Gregory D.; van Grondelle, R.; Malý, P.

    2016-01-01

    When exciting a complex molecular system with a short optical pulse, all chromophores present in the system can be excited. The resulting superposition of electronically and vibrationally excited states evolves in time, which is monitored with transient absorption spectroscopy. We present a

  1. On the origin of cyclotron lines in the spectra of X-ray pulsars

    Directory of Open Access Journals (Sweden)

    Mushtukov A. A.

    2014-01-01

    Full Text Available Cyclotron resonance scattering features are observed in the spectra of some X-ray pulsars and show significant changes in the line energy with the pulsar luminosity. In a case of bright sources, the line centroid energy is anti-correlated with the luminosity. Such a behaviour is often associated with the onset and growth of the accretion column, which is believed to be the origin of the observed emission and the cyclotron lines. However, this scenario inevitably implies large gradient of the magnetic field strength within the line-forming region, and it makes the formation of the observed line-like features problematic. Moreover, the observed variation of the cyclotron line energy is much smaller than could be anticipated for the corresponding luminosity changes. We argue that a more physically realistic situation is that the cyclotron line forms when the radiation emitted by the accretion column is reflected from the neutron star surface. The idea is based on the facts that a substantial part of column luminosity is intercepted by the neutron star surface and the reflected radiation should contain absorption features. The reflection model is developed and applied to explain the observed variations of the cyclotron line energy in a bright X-ray pulsar V 0332+53 over a wide range of luminosities.

  2. Influence of ultrafast carrier dynamics on semiconductor absorption spectra

    CERN Document Server

    Ouerdane, H

    2001-01-01

    set of coupled rate equations. We obtained a good qualitative agreement with experiments and further insight into the interplay between the various dynamical processes by varying the phenomenological parameters entering the rate equations. In particular we found that the carrier spin-flip occurs on a relatively long time scale (several tens of picoseconds) compared to the carrier distributions relaxation and thermalization (a picosecond or less). We also could monitor the time evolution of the plasma density, energy, temperature and screening. In this thesis, we also studied the photoluminescence in II-VI quantum wells at room temperature. We built a mathematical model to account for Coulomb correlations that are expected to strongly influence the spontaneous emission rate in these materials. We assumed the 1s exciton-free electron scattering to be the main process leading an exciton to the photon line before recombination. The excitonic wavefunctions in a 2D screened Coulomb potential were calculated using t...

  3. Media effects on the optical absorption spectra of silver clusters embedded in rara gas matrices

    International Nuclear Information System (INIS)

    Fedrigo, S.; Harbich, W.; Buttet, J.

    1993-01-01

    The optical absorption of small mass selected Ag n -clusters (n=7, 11, 15, 21) embedded in solid Ar, Kr and Xe has been measured. The absorption spectra show 1 to 3 major peaks between 3 and 4.5 eV, depending on the cluster size. Changing the matrix gas Ar→Kr→Xe induces a redshift which is comparable for all sizes studied and does not affect the main structure of the absorption spectra. We propose a scheme to estimate the gas phase value of the absorption energies which is in fair agreement with an estimation obtained by a simple model based on a Drude metal. (author). 10 refs, 2 figs

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

    International Nuclear Information System (INIS)

    Pelece, I.

    2008-01-01

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

  5. A Novel Acoustic Sensor Approach to Classify Seeds Based on Sound Absorption Spectra

    Directory of Open Access Journals (Sweden)

    Ole Green

    2010-11-01

    Full Text Available A non-destructive and novel in situ acoustic sensor approach based on the sound absorption spectra was developed for identifying and classifying different seed types. The absorption coefficient spectra were determined by using the impedance tube measurement method. Subsequently, a multivariate statistical analysis, i.e., principal component analysis (PCA, was performed as a way to generate a classification of the seeds based on the soft independent modelling of class analogy (SIMCA method. The results show that the sound absorption coefficient spectra of different seed types present characteristic patterns which are highly dependent on seed size and shape. In general, seed particle size and sphericity were inversely related with the absorption coefficient. PCA presented reliable grouping capabilities within the diverse seed types, since the 95% of the total spectral variance was described by the first two principal components. Furthermore, the SIMCA classification model based on the absorption spectra achieved optimal results as 100% of the evaluation samples were correctly classified. This study contains the initial structuring of an innovative method that will present new possibilities in agriculture and industry for classifying and determining physical properties of seeds and other materials.

  6. A novel acoustic sensor approach to classify seeds based on sound absorption spectra.

    Science.gov (United States)

    Gasso-Tortajada, Vicent; Ward, Alastair J; Mansur, Hasib; Brøchner, Torben; Sørensen, Claus G; Green, Ole

    2010-01-01

    A non-destructive and novel in situ acoustic sensor approach based on the sound absorption spectra was developed for identifying and classifying different seed types. The absorption coefficient spectra were determined by using the impedance tube measurement method. Subsequently, a multivariate statistical analysis, i.e., principal component analysis (PCA), was performed as a way to generate a classification of the seeds based on the soft independent modelling of class analogy (SIMCA) method. The results show that the sound absorption coefficient spectra of different seed types present characteristic patterns which are highly dependent on seed size and shape. In general, seed particle size and sphericity were inversely related with the absorption coefficient. PCA presented reliable grouping capabilities within the diverse seed types, since the 95% of the total spectral variance was described by the first two principal components. Furthermore, the SIMCA classification model based on the absorption spectra achieved optimal results as 100% of the evaluation samples were correctly classified. This study contains the initial structuring of an innovative method that will present new possibilities in agriculture and industry for classifying and determining physical properties of seeds and other materials.

  7. Temperature dependence of absorption spectra of P-type GaP

    International Nuclear Information System (INIS)

    Mounir, M.; Balloomal, L.S.

    1985-10-01

    The theoretical analysis of the optical absorption due to band-impurity (impurity-band) electron transitions involving deep impurity levels in semi-conductors is considered. Also the data of the experimental absorption spectra of GaP were performed at room temperature and the results were found to be in agreement with the theoretical results if the electron-phonon interaction is taken into consideration. (author)

  8. Lack of dust in quasar absorption line systems

    International Nuclear Information System (INIS)

    Jura, M.

    1977-01-01

    It is stated that the origin of absorption line systems in quasars is still uncertain. Most such systems apparently have atomic hydrogen column densities of the order of 10 19 /cm 2 , but at least two quasars, 1331 + 170 and PHL957, have such strong Lyman α absorption lines that atomic hydrogen column densities of the order of 10 21 /cm 2 are indicated. It should be possible to observe the dust produced 2,200 A extinction feature as it is red shifted into the visible, and to determine whether absorption line systems are produced in spiral galaxies where the dust content is similar to that in the interstellar medium. It has been argued that the emission line regions of quasars generally lack dust and that towards PHL957 the 2,200 A feature is absent. The present author argues that dust similar to that found in the interstellar medium is not found towards the quasars 1331 + 170 and PHL957. This could explain why H 2 is not found towards PHL957, and it indicates that the absorption line systems in quasars are not produced in spiral galaxies similar to our own. It seems from the analysis presented that the dust-to-gas ratio towards 1331 + 170 is at least a factor of 20 less than in the interstellar medium, and there is no reason to suppose that this lack of dust results from a lack of metals It is concluded that there seems to be a lack of normal dust towards PHL957 by at least a factor of two; and that the absorption region towards 1331 + 170 and probably the region towards PHL957 are lacking dust similar to that in our own galaxy. This can explain the lack of H 2 in these systems. (U.K.)

  9. Automated generation and ensemble-learned matching of X-ray absorption spectra

    Science.gov (United States)

    Zheng, Chen; Mathew, Kiran; Chen, Chi; Chen, Yiming; Tang, Hanmei; Dozier, Alan; Kas, Joshua J.; Vila, Fernando D.; Rehr, John J.; Piper, Louis F. J.; Persson, Kristin A.; Ong, Shyue Ping

    2018-03-01

    X-ray absorption spectroscopy (XAS) is a widely used materials characterization technique to determine oxidation states, coordination environment, and other local atomic structure information. Analysis of XAS relies on comparison of measured spectra to reliable reference spectra. However, existing databases of XAS spectra are highly limited both in terms of the number of reference spectra available as well as the breadth of chemistry coverage. In this work, we report the development of XASdb, a large database of computed reference XAS, and an Ensemble-Learned Spectra IdEntification (ELSIE) algorithm for the matching of spectra. XASdb currently hosts more than 800,000 K-edge X-ray absorption near-edge spectra (XANES) for over 40,000 materials from the open-science Materials Project database. We discuss a high-throughput automation framework for FEFF calculations, built on robust, rigorously benchmarked parameters. FEFF is a computer program uses a real-space Green's function approach to calculate X-ray absorption spectra. We will demonstrate that the ELSIE algorithm, which combines 33 weak "learners" comprising a set of preprocessing steps and a similarity metric, can achieve up to 84.2% accuracy in identifying the correct oxidation state and coordination environment of a test set of 19 K-edge XANES spectra encompassing a diverse range of chemistries and crystal structures. The XASdb with the ELSIE algorithm has been integrated into a web application in the Materials Project, providing an important new public resource for the analysis of XAS to all materials researchers. Finally, the ELSIE algorithm itself has been made available as part of veidt, an open source machine-learning library for materials science.

  10. Polarized absorption spectra of aromatic radicals in stretched polymer film, 4. Radical ions of 9-substituted anthracenes. [Gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Hiratsuka, Hiroshi; Nakamura, Hitoshi; Tanizaki, Yoshie; Nakajima, Keihachiro (Tokyo Inst. of Tech. (Japan). Faculty of Science)

    1982-11-01

    Radical ions of some 9-substituted anthracene derivatives have been prepared in polymer film by gamma -irradiation at 77 K. By use of the polarized absorption spectra of these radical ions, the absorption spectra have been resolved into two components (resolved spectra), the transition moments of which are polarized parallel to the molecular long and short axes, respectively. Correlation of the characteristic absorption bands is discussed briefly.

  11. Identification of beryllium hydride isotopomer lines in sunspot umbral spectra

    Directory of Open Access Journals (Sweden)

    Shanmugavel R.

    2008-01-01

    Full Text Available A high resolution spectrum of FTS sunspot umbra of NSO/Kitt Peak was used to conduct a search for the molecular absorption lines due to BeH, BeD and BeT isotopomers. Analysis led to estimates of identification of the molecular lines of bands A - X (0,0, (1,1 and (2,2 for BeH, A - X (0,0, (1,1, (2,2 and (3,3 for BeD and of A - X (0,0, (1,1 and (2,2 for BeT. Among the identified lines, those which are well resolved were selected for measurements to calculate equivalent widths. The values of effective rotational temperature T were estimated for bands A - X(1,1 and (2,2 of BeH, A - X(1,1 of BeD and A - X(2,2 of BeT to be 4228K, 4057K, 3941K and 3243K respectively.

  12. Identification of Beryllium Hydride Isotopomer Lines in Sunspot Umbral Spectra

    Directory of Open Access Journals (Sweden)

    Shanmugavel, R.

    2008-06-01

    Full Text Available A high resolution spectrum of FTS sunspot umbra of NSO/Kitt Peak was used to conduct a search for the molecular absorption lines due to BeH, BeD and BeT isotopomers. Analysis led to estimates of identification of the molecular lines of bands A - X (0,0, (1,1 and (2,2 for BeH, A - X (0,0, (1,1, (2,2 and (3,3 for BeD and of A - X (0,0, (1,1 and (2,2 for BeT. Among the identified lines, those which are well resolved were selected for measurements to calculate equivalent widths. The values of effective rotational temperature T were estimated for bands A - X(1,1 and (2,2 of BeH, A - X(1,1 of BeD and A - X(2,2 of BeT to be 4228K, 4057K, 3941K and 3243K respectively.

  13. X-ray-selected broad absorption line quasi-stellar objects

    Science.gov (United States)

    Page, M. J.; Carrera, F. J.; Ceballos, M.; Corral, A.; Ebrero, J.; Esquej, P.; Krumpe, M.; Mateos, S.; Rosen, S.; Schwope, A.; Streblyanska, A.; Symeonidis, M.; Tedds, J. A.; Watson, M. G.

    2017-02-01

    We study a sample of six X-ray-selected broad absorption line (BAL) quasi-stellar objects (QSOs) from the XMM-Newton Wide Angle Survey. All six objects are classified as BALQSOs using the classic balnicity index, and together they form the largest sample of X-ray-selected BALQSOs. We find evidence for absorption in the X-ray spectra of all six objects. An ionized absorption model applied to an X-ray spectral shape that would be typical for non-BAL QSOs (a power law with energy index α = 0.98) provides acceptable fits to the X-ray spectra of all six objects. The optical to X-ray spectral indices, αOX, of the X-ray-selected BALQSOs, have a mean value of = 1.69 ± 0.05, which is similar to that found for X-ray-selected and optically selected non-BAL QSOs of a similar ultraviolet luminosity. In contrast, optically selected BALQSOs typically have much larger αOX and so are characterized as being X-ray weak. The results imply that X-ray selection yields intrinsically X-ray bright BALQSOs, but their X-ray spectra are absorbed by a similar degree to that seen in optically selected BALQSO samples; X-ray absorption appears to be ubiquitous in BALQSOs, but X-ray weakness is not. We argue that BALQSOs sit at one end of a spectrum of X-ray absorption properties in QSOs related to the degree of ultraviolet absorption in C IV 1550 Å.

  14. Multi-Photon Absorption Spectra: A Comparison Between Transmittance Change and Fluorescence Methods

    Science.gov (United States)

    2015-05-21

    AFRL-OSR-VA-TR-2015-0134 multi-photon absorption spectra Cleber Mendonca INSTITUTO DE FISICA DE SAO CARLOS Final Report 05/21/2015 DISTRIBUTION A...5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Instituto de Fisica de Sao Carlos - Universidade de Sao Paulo Av

  15. Optical absorption and magnetic circular dichroism spectra of thiouracils: a quantum mechanical study in solution

    DEFF Research Database (Denmark)

    Martínez-Fernández, L.; Fahleson, Tobias; Norman, Patrick

    2017-01-01

    The excited electronic states of 2-thiouracil, 4-thiouracil and 2,4-dithiouracil, the analogues of uracil where the carbonyl oxygens are substituted by sulphur atoms, have been investigated by computing the magnetic circular dichroism (MCD) and one-photon absorption (OPA) spectra at the time...

  16. A Polarized Atmospheric Radiative Transfer Model for Calculations of Spectra of the Stokes Parameters of Shortwave Radiation Based on the Line-by-Line and Monte Carlo Methods

    Directory of Open Access Journals (Sweden)

    Boris Fomin

    2012-10-01

    Full Text Available This paper presents a new version of radiative transfer model called the Fast Line-by-Line Model (FLBLM, which is based on the Line-by-Line (LbL and Monte Carlo (MC methods and rigorously treats particulate and molecular scattering alongside absorption. The advantage of this model consists in the use of the line-by-line model that allows for the computing of high-resolution spectra quite quickly. We have developed the model by taking into account the polarization state of light and carried out some validations by comparison against benchmark results. FLBLM calculates the Stokes parameters spectra of shortwave radiation in vertically inhomogeneous atmospheres. This update makes the model applicable for the assessment of cloud and aerosol influence on radiances as measured by the SW high-resolution polarization spectrometers. In sample results we demonstrate that the high-resolution spectra of the Stokes parameters contain more detailed information about clouds and aerosols than the medium- and low-resolution spectra wherein lines are not resolved. The presented model is rapid enough for many practical applications (e.g., validations and might be useful especially for the remote sensing. FLBLM is suitable for development of the reliable technique for retrieval of optical and microphysical properties of clouds and aerosols from high-resolution satellites data.

  17. Equilibrium Structures and Absorption Spectra for SixOy Molecular Clusters using Density Functional Theory

    Science.gov (United States)

    2017-05-05

    Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/6390--17-9724 Equilibrium Structures and Absorption Spectra for SixOy Molecular Clusters...TELEPHONE NUMBER (include area code) b. ABSTRACT c. THIS PAGE 18. NUMBER OF PAGES 17. LIMITATION OF ABSTRACT Equilibrium Structures and Absorption...Introduction……………………………………………………………………….………………..1 Calculation of Absorption Spectra using DFT ……………………………………………..…..….1 DFT Calculation of Equilibrium

  18. Quantitative comparisons of absorption cross-section spectra and integrated intensities of HFC-143a

    International Nuclear Information System (INIS)

    Le Bris, Karine; Graham, Laura

    2015-01-01

    The integrated absorption cross-sections of HFC-143a (CH 3 CF 3 ) differ substantially in the literature. This leads to an important uncertainty on the value of the radiative efficiency of this molecule. The ambiguity on the absorption cross-sections of HFC-143a is highlighted by the existence of two significantly different datasets in the HITRAN database. To solve the issue, we performed high-resolution Fourier transform infrared laboratory measurements of HFC-13a and compared the spectra with the two HITRAN datasets and with the data from the Pacific Northwest National Laboratory (PNNL). The experimental methods and data analysis techniques are examined and typical sources of errors are discussed. The integrated intensities of the main bands are compared to other literature values. It was found that the integrated absorption cross-section values in the highest range – around 13.8×10 −17 cm.molecule −1 in the 570–1500 cm −1 spectral band – show the most consistency between authors. - Highlights: • Large discrepancies exist between authors on the absorption spectra of HFC-143a. • We present new cross-section spectra of a pure vapour at 263, 273 and 283 K. • The data were compared to literature values. • Total integrated intensities in the highest range are the most consistent. • The radiative efficiency of HFC-143a should be revised upward

  19. Temperature dependent absorption spectra of Br(-), Br2(•-), and Br3(-) in aqueous solutions.

    Science.gov (United States)

    Lin, Mingzhang; Archirel, Pierre; Van-Oanh, Nguyen Thi; Muroya, Yusa; Fu, Haiying; Yan, Yu; Nagaishi, Ryuji; Kumagai, Yuta; Katsumura, Yosuke; Mostafavi, Mehran

    2011-05-05

    The absorption spectra of Br(2)(•-) and Br(3)(-) in aqueous solutions are investigated by pulse radiolysis techniques from room temperature to 380 and 350 °C, respectively. Br(2)(•-) can be observed even in supercritical conditions, showing that this species could be used as a probe in pulse radiolysis at high temperature and even under supercritical conditions. The weak temperature effect on the absorption spectra of Br(2)(•-) and Br(3)(-) is because, in these two systems, the transition occurs between two valence states; for example, for Br(2)(-) we have (2)Σ(u) → (2)Σ(g) transition. These valence transitions involve no diffuse final state. However, the absorption band of Br(-) undergoes an important red shift to longer wavelengths. We performed classical dynamics of hydrated Br(-) system at 20 and 300 °C under pressure of 25 MPa. The radial distribution functions (rdf's) show that the strong temperature increase (from 20 to 300 °C) does not change the radius of the solvent first shell. On the other hand, it shifts dramatically (by 1 Å) the second maximum of the Br-O rdf and introduces much disorder. This shows that the first water shell is strongly bound to the anion whatever the temperature. The first two water shells form a cavity of a roughly spherical shape around the anion. By TDDFT method, we calculated the absorption spectra of hydrated Br(-) at two temperatures and we compared the results with the experimental data.

  20. Plant phenolics and absorption features in vegetation reflectance spectra near 1.66 μm

    Science.gov (United States)

    Kokaly, Raymond F.; Skidmore, Andrew K.

    2015-12-01

    Past laboratory and field studies have quantified phenolic substances in vegetative matter from reflectance measurements for understanding plant response to herbivores and insect predation. Past remote sensing studies on phenolics have evaluated crop quality and vegetation patterns caused by bedrock geology and associated variations in soil geochemistry. We examined spectra of pure phenolic compounds, common plant biochemical constituents, dry leaves, fresh leaves, and plant canopies for direct evidence of absorption features attributable to plant phenolics. Using spectral feature analysis with continuum removal, we observed that a narrow feature at 1.66 μm is persistent in spectra of manzanita, sumac, red maple, sugar maple, tea, and other species. This feature was consistent with absorption caused by aromatic Csbnd H bonds in the chemical structure of phenolic compounds and non-hydroxylated aromatics. Because of overlapping absorption by water, the feature was weaker in fresh leaf and canopy spectra compared to dry leaf measurements. Simple linear regressions of feature depth and feature area with polyphenol concentration in tea resulted in high correlations and low errors (% phenol by dry weight) at the dry leaf (r2 = 0.95, RMSE = 1.0%, n = 56), fresh leaf (r2 = 0.79, RMSE = 2.1%, n = 56), and canopy (r2 = 0.78, RMSE = 1.0%, n = 13) levels of measurement. Spectra of leaves, needles, and canopies of big sagebrush and evergreens exhibited a weak absorption feature centered near 1.63 μm, short ward of the phenolic compounds, possibly consistent with terpenes. This study demonstrates that subtle variation in vegetation spectra in the shortwave infrared can directly indicate biochemical constituents and be used to quantify them. Phenolics are of lesser abundance compared to the major plant constituents but, nonetheless, have important plant functions and ecological significance. Additional research is needed to advance our understanding of the spectral influences

  1. In-line evanescent-wave microfluidic absorption sensor based on an embedded optical microfiber coil

    OpenAIRE

    Lorenzi, R.; Jung, Y.; Brambilla, G.

    2011-01-01

    We present the absorption spectra collected with an evanescent-field absorption sensor. The device comprises an active fluidic channel with an embedded microfiber coil resonator. Deviations from Beer-Lambert law will be discussed in terms of adsorption mechanism.

  2. Absorption spectra measurements of the x-ray radiation heated SiO2 aerogel plasma in 'dog-bone' targets irradiated by high power laser pulses

    Science.gov (United States)

    Zhang, Y.; Dong, Q.-L.; Wang, S.-J.; Li, Y.-T.; Zhang, J.; Wei, H.-G.; Shi, J.-R.; Zhao, G.; Zhang, J.-Y.; Wen, T.-S.; Zhang, W.-H.; Hu, X.; Liu, S.-Y.; Ding, Y.-K.; Zhang, L.; Tang, Y.-J.; Zhang, B.-H.; Zheng, Z.-J.; Nishimura, H.; Fujioka, S.; Takabe, H.

    2008-05-01

    We studied the opacity effect of the SiO2 aerogel plasma heated by x-ray radiation produced by high power laser pulses irradiating the inner surface of golden 'dog-bone' targets. The PET crystal spectrometer was used to measure the absorption spectra of the plasmas in the range from 6.4 Å to 7.4 Å, among which the line emissions involving the K shell of Si ions from He-like to neutral atom were located. The experimental results were analyzed with Detailed-Level-Accounting method. As the plasma temperature increased, the characteristic lines of highly ionized ions gradually dominated the absorption spectrum.

  3. Observations of absorption lines from highly ionized atoms. [of interstellar medium

    Science.gov (United States)

    Jenkins, Edward B.

    1987-01-01

    In the ultraviolet spectra of hot stars, absorption lines can be seen from highly ionized species in the interstellar medium. Observations of these features which have been very influential in revising the perception of the medium's various physical states, are discussed. The pervasiveness of O 6 absorption lines, coupled with complementary observations of a diffuse background in soft X-rays and EUV radiation, shows that there is an extensive network of low density gas (n approx. few x 0.001/cu cm) existing at coronal temperatures log T = 5.3 or 6.3. Shocks created by supernova explosions or mass loss from early-type stars can propagate freely through space and eventually transfer a large amount of energy to the medium. To create the coronal temperatures, the shocks must have velocities in excess of 150 km/sec; shocks at somewhat lower velocity (v = 100 km/sec) can be directly observed in the lines of Si3. Observations of other lines in the ultraviolet, such as Si 4V and C 5, may highlight the widespread presence of energetic UV radiation from very hot, dwarf stars. More advanced techniques in visible and X-ray astronomical spectroscopy may open up for inspection selected lines from atoms in much higher stages of ionization.

  4. Modeling of fluorescence line-narrowed spectra in weakly coupled dimers in the presence of excitation energy transfer

    Science.gov (United States)

    Lin, Chen; Reppert, Mike; Feng, Ximao; Jankowiak, Ryszard

    2014-07-01

    This work describes simple analytical formulas to describe the fluorescence line-narrowed (FLN) spectra of weakly coupled chromophores in the presence of excitation energy transfer (EET). Modeling studies for dimer systems (assuming low fluence and weak coupling) show that the FLN spectra (including absorption and emission spectra) calculated for various dimers using our model are in good agreement with spectra calculated by: (i) the simple convolution method and (ii) the more rigorous treatment using the Redfield approach [T. Renger and R. A. Marcus, J. Chem. Phys. 116, 9997 (2002)]. The calculated FLN spectra in the presence of EET of all three approaches are very similar. We argue that our approach provides a simplified and computationally more efficient description of FLN spectra in the presence of EET. This method also has been applied to FLN spectra obtained for the CP47 antenna complex of Photosystem II reported by Neupane et al. [J. Am. Chem. Soc. 132, 4214 (2010)], which indicated the presence of uncorrelated EET between pigments contributing to the two lowest energy (overlapping) exciton states, each mostly localized on a single chromophore. Calculated and experimental FLN spectra for CP47 complex show very good qualitative agreement.

  5. The UV absorption of nucleobases: semi-classical ab initio spectra simulations

    Czech Academy of Sciences Publication Activity Database

    Barbatti, M.; Aquino, A. J. A.; Lischka, Hans

    2010-01-01

    Roč. 12, č. 19 (2010), s. 4959-4967 ISSN 1463-9076 R&D Projects: GA MŠk LC512 Grant - others:Special Research Program(AT) P18411-N19 Institutional research plan: CEZ:AV0Z40550506 Keywords : semi-classical simulations * UV absorption spectra * nucleobases Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.454, year: 2010

  6. QM/MM-Based Calculations of Absorption and Emission Spectra of LSSmOrange Variants.

    Science.gov (United States)

    Bergeler, Maike; Mizuno, Hideaki; Fron, Eduard; Harvey, Jeremy N

    2016-12-15

    The goal of this computational work is to gain new insight into the photochemistry of the fluorescent protein (FP) LSSmOrange. This FP is of interest because besides exhibiting the eponymous large spectral shift (LSS) between the absorption and emission energies, it has been experimentally observed that it can also undergo a photoconversion process, which leads to a change in the absorption wavelength of the chromophore (from 437 to 553 nm). There is strong experimental evidence that this photoconversion is caused by decarboxylation of a glutamate located in the close vicinity of the chromophore. Still, the exact chemical mechanism of the decarboxylation process as well as the precise understanding of structure-property relations in the measured absorption and emission spectra is not yet fully understood. Therefore, hybrid quantum mechanics/molecular mechanics (QM/MM) calculations are performed to model the absorption and emission spectra of the original and photoconverted forms of LSSmOrange. The necessary force-field parameters of the chromophore are optimized with CGenFF and the FFToolkit. A thorough analysis of QM methods to study the excitation energies of this specific FP chromophore has been carried out. Furthermore, the influence of the size of the QM region has been investigated. We found that QM/MM calculations performed with time-dependent density functional theory (CAM-B3LYP/D3/6-31G*) and QM calculations performed with the semiempirical ZIndo/S method including a polarizable continuum model can describe the excitation energies reasonably well. Moreover, already a small QM region size seems to be sufficient for the study of the photochemistry in LSSmOrange. Especially, the calculated ZIndo spectra are in very good agreement with the experimental ones. On the basis of the spectra obtained, we could verify the experimentally assigned structures.

  7. Transient C IV broad absorption lines in radio-detected QSOs

    Science.gov (United States)

    Vivek, M.; Srianand, R.; Gupta, N.

    2016-01-01

    We study the transient (I.e. emerging or disappearing) C IV broad absorption line (BAL) components in 50 radio-detected QSOs using multi-epoch spectra available in Sloan Digital Sky Survey Data Release-10. We report the detection of six BALQSOs having at least one distinct transient C IV absorption component. Based on the structure function analysis of optical light curves, we suggest that the transient absorption is unlikely to be triggered by continuum variations. Transient absorption components usually have low C IV equivalent widths (10 000 km s-1) and typically occur over rest-frame time-scales >800 d. The detection rate of transient C IV absorption seen in our sample is higher than that reported in the literature. Using a control sample of QSOs, we show that this difference is most likely due to the longer monitoring time-scale of sources in our sample while the effect of small number statistics cannot be ignored. Thus, in order to establish the role played by radio jets in driving the BAL outflows, we need a larger sample of radio-detected BALs monitored over more than 3 yr in the QSO's rest frame. We also find that the transient phenomenon in radio-detected and radio-quiet BALs does not depend on any of the QSO properties, I.e. the Eddington ratio, black hole mass, bolometric luminosity and optical-to-IR colours. All this suggests that transient BAL phenomenon is simply the extreme case of BAL variability.

  8. Atomic Data Revisions for Improving Absorption Line Studies of the Interstellar, Circumgalactic, and Intergalactic Medium

    Science.gov (United States)

    Cashman, Frances; Kulkarni, Varsha; Kisielius, Romas; Ferland, Gary; Bogdanovich, Pavel

    2018-01-01

    Surveying and studying galaxies at different epochs is essential to understanding how galaxies evolve. Atomic spectroscopy is used to study the gas in and around galaxies by means of the absorption features in the spectra of background quasars. Element abundances derived from the measurement of observed lines in these quasar absorption systems rely on accurate atomic data such as the oscillator strength of electric dipole transitions. We have produced a compilation of recommended oscillator strengths for 576 key transitions for wavelengths longward of 911.753 Angstroms (the H I Lyman limit). This compilation focuses on the recent findings from numerous theoretical and experimental physicists for ions of astrophysical interest that have been observed in the interstellar medium (ISM), the circumgalactic medium (CGM), and the intergalactic medium (IGM), for selected elements ranging from C to Pb. Differences between the former and the newly recommended values are greater than 25% for approximately 22% of lines with updated oscillator strength values. We encourage future absorption line studies of the ISM, CGM, and IGM medium to use this compilation.This work was supported in part by NSF-AST/1108830, NASA/STScI support for HST GO-12536, and a NASA/SC Space Grant graduate fellowship.

  9. The electronic absorption spectra of pyridine azides, solvent-solute interaction

    Science.gov (United States)

    Abu-Eittah, Rafie H.; Khedr, Mahmoud K.

    2009-01-01

    The electronic absorption spectra of: 2-, 3-, and 4-azidopyridines have been investigated in a wide variety of polar and non-polar solvents. According to Onsager model, the studied spectra indicate that the orientation polarization of solvent dipoles affects the electronic spectrum much stronger than the induction polarization of solvent dipoles. The effect of solvent dipole moment predominates that of solvent refractive index in determining the values of band maxima of an electronic spectrum. The spectra of azidopyridines differ basically from these of pyridine or mono-substituted pyridine. Results at hand indicate that the azide group perturbs the pyridine ring in the case of 3-azidopyridine much more than it does in the case of 2-azidopyridine. This result agrees with the predictions of the resonance theory. Although the equilibrium ⇌ azide tetrazole is well known, yet the observed spectra prove that such an equilibrium does not exist at the studied conditions. The spectra of the studied azidopyridines are characterized by the existence of overlapping transitions. Gaussian analysis is used to obtain nice, resolved spectra. All the observed bands correspond to π → π* transitions, n → π* may be overlapped with the stronger π → π* ones.

  10. Exciton Absorption Spectra by Linear Response Methods:Application to Conjugated Polymers

    Energy Technology Data Exchange (ETDEWEB)

    Mosquera, Martin A.; Jackson, Nicholas E.; Fauvell, Thomas J.; Kelley, Matthew S.; Chen, Lin X.; Schatz, George C.; Ratner, Mark A.

    2017-01-01

    The theoretical description of the timeevolution of excitons requires, as an initial step, the calculation of their spectra, which has been inaccessible to most users due to the high computational scaling of conventional algorithms and accuracy issues caused by common density functionals. Previously (J. Chem. Phys. 2016, 144, 204105), we developed a simple method that resolves these issues. Our scheme is based on a two-step calculation in which a linear-response TDDFT calculation is used to generate orbitals perturbed by the excitonic state, and then a second linear-response TDDFT calculation is used to determine the spectrum of excitations relative to the excitonic state. Herein, we apply this theory to study near-infrared absorption spectra of excitons in oligomers of the ubiquitous conjugated polymers poly(3-hexylthiophene) (P3HT), poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV), and poly(benzodithiophene-thieno[3,4-b]thiophene) (PTB7). For P3HT and MEH-PPV oligomers, the calculated intense absorption bands converge at the longest wavelengths for 10 monomer units, and show strong consistency with experimental measurements. The calculations confirm that the exciton spectral features in MEH-PPV overlap with those of the bipolaron formation. In addition, our calculations identify the exciton absorption bands in transient absorption spectra measured by our group for oligomers (1, 2, and 3 units) of PTB7. For all of the cases studied, we report the dominant orbital excitations contributing to the optically active excited state-excited state transitions, and suggest a simple rule to identify absorption peaks at the longest wavelengths. We suggest our methodology could be considered for further evelopments in theoretical transient spectroscopy to include nonadiabatic effects, coherences, and to describe the formation of species such as charge-transfer states and polaron pairs.

  11. Urbach tail in the absorption spectra of 2H-WSe{sub 2} layered crystals

    Energy Technology Data Exchange (ETDEWEB)

    Hu, S.Y. [Department of Electrical Engineering, Tung Fang Institute of Technology, Hunei Township, Kaohsiung County 82941 (China); Lee, Y.C. [Department of Electronic Engineering, Research Center for Micro/Nano Technology, Tung Nan Institute of Technology, Shen-Keng, Taipei 22202 (China); Shen, J.L.; Chen, K.W. [Department of Physics, Chung Yuan Christian University, Chung-Li, Tao-Yuan 32023 (China); Huang, Y.S. [Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei 10607 (China)

    2007-07-15

    Urbach's rule and steepness parameter of 2H-WSe{sub 2} layered crystals have been studied via the absorption spectra from the photoconductivity (PC) measurements in the temperature range of 15-300 K. From the analysis of the temperature-dependent band gap with Varshni semi-empirical equation, the Debye temperature was estimated as 160 K while the Einstein temperature was around 125 K from the Einstein oscillator model. The effective phonon energy was estimated successfully from the temperature dependence of the Urbach energy extracted from the PC spectra and the value was found out to be well correlated to the active E{sub 1g} mode observed in the Raman spectra of 2H-WSe{sub 2}. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. Spectra of optical absorption and energy levels diagram of Er3+ ions in bulk crystals of aluminum nitride

    Science.gov (United States)

    Poletaev, N. K.; Skvortsov, A. P.

    2017-12-01

    The absorption spectra of the Er3+ ions embedded in the AlN matrix have been investigated. The admixture of erbium was introduced in bulk AlN crystals by diffusion. The absorption lines, which are associated with the intraconfigurational electronic f- f-transitions from the ground 4 I 15/2-state to the levels of ion Er3+ excited states have been observed in the spectral range of 370-700 nm. The transitions to the state levels 4 F 9/2, 2 H 11/2, 4 F 7/2, 4 F 5/2, 2 H 9/2, and 4 G 11/2 have been investigated in detail at the temperature T = 2 K. The number of the observed lines for these transitions coincides with the theoretically possible one for the electronic f- f-transitions in the ions Er3+, which are in the crystal field with the symmetry below cubic. The narrowness of the observed lines and their number convincingly testify the replacement of preferably one regular crystalline position by erbium ions. The implementation of Er3+ in the Al3+ position with the local symmetry C 3v appears the most probable. The energy positions of the levels of excited states for the investigated transitions have been determined. The diagram of the Er3+ ion energy levels in the AlN crystals has been built.

  13. In vivo determination of the absorption and scattering spectra of the human prostate during photodynamic therapy

    Science.gov (United States)

    Finlay, Jarod C.; Zhu, Timothy C.; Dimofte, Andreea; Stripp, Diana C. H.; Malkowicz, S. B.; Whittington, Richard; Miles, Jeremy; Glatstein, Eli; Hahn, Stephen M.

    2004-06-01

    A continuing challenge in photodynamic therapy is the accurate in vivo determination of the optical properties of the tissue being treated. We have developed a method for characterizing the absorption and scattering spectra of prostate tissue undergoing PDT treatment. Our current prostate treatment protocol involves interstitial illumination of the organ via cylindrical diffusing optical fibers (CDFs) inserted into the prostate through clear catheters. We employ one of these catheters to insert an isotropic white light point source into the prostate. An isotropic detection fiber connected to a spectrograph is inserted into a second catheter a known distance away. The detector is moved along the catheter by a computer-controlled step motor, acquiring diffuse light spectra at 2 mm intervals along its path. We model the fluence rate as a function of wavelength and distance along the detector"s path using an infinite medium diffusion theory model whose free parameters are the absorption coefficient μa at each wavelength and two variables A and b which characterize the reduced scattering spectrum of the form μ"s = Aλ-b. We analyze our spectroscopic data using a nonlinear fitting algorithm to determine A, b, and μa at each wavelength independently; no prior knowledge of the absorption spectrum or of the sample"s constituent absorbers is required. We have tested this method in tissue simulating phantoms composed of intralipid and the photosensitizer motexafin lutetium (MLu). The MLu absorption spectrum recovered from the phantoms agrees with that measured in clear solution, and μa at the MLu absorption peak varies linearly with concentration. The ´"s spectrum reported by the fit is in agreement with the known scattering coefficient of intralipid. We have applied this algorithm to spectroscopic data from human patients sensitized with MLu (2 mg kg-1) acquired before and after PDT. Before PDT, the absorption spectra we measure include the characteristic MLu absorption

  14. Determining CDOM Absorption Spectra in Diverse Aquatic Environments Using a Multiple Pathlength, Liquid Core Waveguide System

    Science.gov (United States)

    Miller, Richard L.; Belz, Mathias; DelCastillo, Carlos; Trzaska, Rick

    2001-01-01

    We evaluated the accuracy, sensitivity and precision of a multiple pathlength, liquid core waveguide (MPLCW) system for measuring colored dissolved organic matter (CDOM) absorption in the UV-visible spectral range (370-700 nm). The MPLCW has four optical paths (2.0, 9.8, 49.3, and 204 cm) coupled to a single Teflon AF sample cell. Water samples were obtained from inland, coastal and ocean waters ranging in salinity from 0 to 36 PSU. Reference solutions for the MPLCW were made having a refractive index of the sample. CDOM absorption coefficients, aCDOM, and the slope of the log-linearized absorption spectra, S, were compared with values obtained using a dual-beam spectrophotometer. Absorption of phenol red secondary standards measured by the MPLCW at 558 nm were highly correlated with spectrophotometer values and showed a linear response across all four pathlengths. Values of aCDOM measured using the MPLCW were virtually identical to spectrophotometer values over a wide range of concentrations. The dynamic range of aCDOM for MPLCW measurements was 0.002 - 231.5 m-1. At low CDOM concentrations spectrophotometric aCDOM were slightly greater than MPLCW values and showed larger fluctuations at longer wavelengths due to limitations in instrument precision. In contrast, MPLCW spectra followed an exponential to 600 nm for all samples.

  15. TDDFT prediction of UV-vis absorption and emission spectra of tocopherols in different media.

    Science.gov (United States)

    Bakhouche, Kahina; Dhaouadi, Zoubeida; Lahmar, Souad; Hammoutène, Dalila

    2015-06-01

    We use the TDDFT/PBE0/6-31+G* method to determine the electronic absorption and emission energies, in different media, of the four forms of tocopherol, which differ by the number and the position of methyl groups on the chromanol. Geometries of the ground state S0 and the first singlet excited state S1 were optimized in the gas phase, and various solvents. The solvent effect is evaluated using an implicit solvation model (IEF-PCM). Our results are compared to the experimental ones obtained for the vitamin E content in several vegetable oils. For all forms of tocopherols, the HOMO-LUMO first vertical excitation is a π-π* transition. Gas phase and non-polar solvents (benzene and toluene) give higher absorption wavelengths than polar solvents (acetone, ethanol, methanol, DMSO, and water); this can be interpreted by a coplanarity between the O-H group and the chroman, allowing a better electronic resonance of the oxygen lone pairs and the aromatic ring, and therefore giving an important absorption wavelength, whereas the polar solvents give high emission wavelengths comparatively to gas phase and non-polar solvents. Fluorescence spectra permit the determination, the separation, and the identification of the four forms of tocopherols by a large difference in emission wavelength values. Graphical Abstract Scheme from process methodological to obtain the absorption and emission spectra for tocopherols.

  16. Decoupling multimode vibrational relaxations in multi-component gas mixtures: Analysis of sound relaxational absorption spectra

    International Nuclear Information System (INIS)

    Zhang Ke-Sheng; Wang Shu; Zhu Ming; Ding Yi; Hu Yi

    2013-01-01

    Decoupling the complicated vibrational—vibrational (V—V) coupling of a multimode vibrational relaxation remains a challenge for analyzing the sound relaxational absorption in multi-component gas mixtures. In our previous work [Acta Phys. Sin. 61 174301 (2012)], an analytical model to predict the sound absorption from vibrational relaxation in a gas medium is proposed. In this paper, we develop the model to decouple the V—V coupled energy to each vibrational—translational deexcitation path, and analyze how the multimode relaxations form the peaks of sound absorption spectra in gas mixtures. We prove that a multimode relaxation is the sum of its decoupled single-relaxation processes, and only the decoupled process with a significant isochoric-molar-heat can be observed as an absorption peak. The decoupling model clarifies the essential processes behind the peaks in spectra arising from the multimode relaxations in multi-component gas mixtures. The simulation validates the proposed decoupling model. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  17. Ultraviolet absorption spectra and kinetics of CH3S and CH2SH radicals

    DEFF Research Database (Denmark)

    Anastasi, C.; Broomfield, M.; Nielsen, O.J.

    1991-01-01

    The ultraviolet absorption spectra of CH3S and CH2SH radicals have been measured between 215 and 380 nm using the pulse-radiolysis/kinetic-absorption method. One absorption band between 250 and 300 nm and one around 215 nm have been tentatively assigned to the CH2SH and CH3S radicals, respectively....... This spectrum has been used to measure the self-reaction rates of these radicals. Rate constants of 4 x 10(-11) and 7 x 10(-11) cm3 molecule-1 s-1 have been measured at 298 K for CH3S and CH2SH recombination, respectively. The possible reaction pathways are discussed....

  18. Absorption Spectra of Ni and Co Nanoparticles using Density Functional Theory

    International Nuclear Information System (INIS)

    Elham Gharibshahi; Elias Saion

    2011-01-01

    Metal nanoparticles (NPs) demonstrate excellent electronic properties due to quantum confinement effects and have tremendous applications in catalysts, optics, single-electron devices, bio-chemical sensors, etc. We propose quantum mechanics method for the calculation of absorption spectra of conduction electrons of some transition metal NPs using time-independent Schrodinger equation and approximate the solution by density functional theory. The total energy functional is obtained from the ground-state energy functional of Thomas-Fermi-Dirac- Weizsaecker atomic system. The absorption function was derived and replaced the density function in the final Euler-Lagrange equation. The total energy functional can then be computed numerically for isolated Ni and Co NPs having fcc lattice structure and different nano sizes. The results show a red-shift absorption peak increase with increasing diameter of nanosphere correspond to the number of atoms required to form nanoparticles of respective sizes. (author)

  19. Identification of MgII Absorption Line Systems from SDSS Quasar ...

    Indian Academy of Sciences (India)

    Motivation. The quasar absorption lines are crucial to our understanding of the Universe since the absorption lines provide a wealth of information on the gaseous Universe from high redshift to present day. The absorption lines can also allow us to probe the metallicity and ionization state of the gas (Wild et al. 2008).

  20. Plant phenolics and absorption features in vegetation reflectance spectra near 1.66 μm

    Science.gov (United States)

    Kokaly, Raymond F.; Skidmore, Andrew K

    2015-01-01

    Past laboratory and field studies have quantified phenolic substances in vegetative matter from reflectance measurements for understanding plant response to herbivores and insect predation. Past remote sensing studies on phenolics have evaluated crop quality and vegetation patterns caused by bedrock geology and associated variations in soil geochemistry. We examined spectra of pure phenolic compounds, common plant biochemical constituents, dry leaves, fresh leaves, and plant canopies for direct evidence of absorption features attributable to plant phenolics. Using spectral feature analysis with continuum removal, we observed that a narrow feature at 1.66 μm is persistent in spectra of manzanita, sumac, red maple, sugar maple, tea, and other species. This feature was consistent with absorption caused by aromatic C-H bonds in the chemical structure of phenolic compounds and non-hydroxylated aromatics. Because of overlapping absorption by water, the feature was weaker in fresh leaf and canopy spectra compared to dry leaf measurements. Simple linear regressions of feature depth and feature area with polyphenol concentration in tea resulted in high correlations and low errors (% phenol by dry weight) at the dry leaf (r2 = 0.95, RMSE = 1.0%, n = 56), fresh leaf (r2 = 0.79, RMSE = 2.1%, n = 56), and canopy (r2 = 0.78, RMSE = 1.0%, n = 13) levels of measurement. Spectra of leaves, needles, and canopies of big sagebrush and evergreens exhibited a weak absorption feature centered near 1.63 μm, short ward of the phenolic compounds, possibly consistent with terpenes. This study demonstrates that subtle variation in vegetation spectra in the shortwave infrared can directly indicate biochemical constituents and be used to quantify them. Phenolics are of lesser abundance compared to the major plant constituents but, nonetheless, have important plant functions and ecological significance. Additional research is needed to advance our understanding of the

  1. Retrieval of phytoplankton cell size from chlorophyll a specific absorption and scattering spectra of phytoplankton.

    Science.gov (United States)

    Zhou, Wen; Wang, Guifen; Li, Cai; Xu, Zhantang; Cao, Wenxi; Shen, Fang

    2017-10-20

    Phytoplankton cell size is an important property that affects diverse ecological and biogeochemical processes, and analysis of the absorption and scattering spectra of phytoplankton can provide important information about phytoplankton size. In this study, an inversion method for extracting quantitative phytoplankton cell size data from these spectra was developed. This inversion method requires two inputs: chlorophyll a specific absorption and scattering spectra of phytoplankton. The average equivalent-volume spherical diameter (ESD v ) was calculated as the single size approximation for the log-normal particle size distribution (PSD) of the algal suspension. The performance of this method for retrieving cell size was assessed using the datasets from cultures of 12 phytoplankton species. The estimations of a(λ) and b(λ) for the phytoplankton population using ESD v had mean error values of 5.8%-6.9% and 7.0%-10.6%, respectively, compared to the a(λ) and b(λ) for the phytoplankton populations using the log-normal PSD. The estimated values of C i ESD v were in good agreement with the measurements, with r 2 =0.88 and relative root mean square error (NRMSE)=25.3%, and relatively good performances were also found for the retrieval of ESD v with r 2 =0.78 and NRMSE=23.9%.

  2. Measurement of Gas and Aerosol Phase Absorption Spectra across the Visible and Near-IR Using Supercontinuum Photoacoustic Spectroscopy.

    Science.gov (United States)

    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).

  3. Possible evidence for a variable fine-structure constant from QSO absorption lines: motivations, analysis and results

    Science.gov (United States)

    Murphy, M. T.; Webb, J. K.; Flambaum, V. V.; Dzuba, V. A.; Churchill, C. W.; Prochaska, J. X.; Barrow, J. D.; Wolfe, A. M.

    2001-11-01

    An experimental search for variation in the fundamental coupling constants is strongly motivated by modern high-energy physics theories. Comparison of quasar (QSO) absorption-line spectra with laboratory spectra provides a sensitive probe for variability of the fine-structure constant, α, over cosmological time-scales. We have previously developed and applied a new method providing an order-of-magnitude gain in precision over previous optical astrophysical constraints. Here we extend that work by including new quasar spectra of damped Lyman-α absorption systems. We also reanalyse our previous lower-redshift data and confirm our initial results. The constraints on α come from simultaneous fitting of absorption lines of subsets of the following species: Mgi, Mgii, Alii, Aliii, Siii, Crii, Feii, Niii and Znii. We present a detailed description of our methods and results based on an analysis of 49 quasar absorption systems (towards 28 QSOs) covering the redshift range [formmu2]0.5quote above is the raw value, not corrected for any of these systematic effects. The only significant systematic effects so far identified, if removed from our data, would lead to a more significant deviation of [formmu5]Δα/α from zero.

  4. Optical absorption spectra of semiconductors and insulators: ab initio calculation of many-body effects

    International Nuclear Information System (INIS)

    Albrecht, Stefan

    1999-01-01

    A method for the inclusion of self-energy and excitonic effects in first-principle calculations of absorption spectra, within the state-of-the-art plane wave pseudopotential approach, is presented. Starting from a ground state calculation, using density functional theory (DFT) in the local density approximation (LDA), we correct the exchange-correlation potential of DFT-LDA with the self-energy applying Hedin's GW approximation to obtain the physical quasiparticles states. The electron-hole interaction is treated solving an effective two-particle equation, which we derive from Hedin's coupled integral equations, leading to the fundamental Bethe-Salpeter equation in an intermediate step. The interaction kernel contains the screened electron-hole Coulomb interaction and the electron-hole exchange effects, which reflect the microscopic structure of the system and are thus also called local-field effects. We obtain the excitonic eigenstates through diagonalization. This allows us a detailed analysis of the optical properties. The application of symmetry properties enables us to reduce the size of the two-particle Hamiltonian matrix, thus minimizing the computational effort. We apply our method to silicon, diamond, lithium oxide and the sodium tetramer. Good agreement with experiment is obtained for the absorption spectra of Si and diamond, the static dielectric constant of diamond, and for the onset of optical absorption of Li 2 O due to discrete bound excitons. We discuss various approximations of our method and show the strong mixing of independent particle transitions to a bound excitonic state in the Na 4 cluster. The influence of ground state calculations on optical spectra is investigated under particular consideration of the pseudopotential generation and we discuss the use of different Brillouin zone point sampling schemes for spectral calculations. (author) [fr

  5. UV-Vis absorption spectra and electronic structure of merocyanines in the gas phase

    Science.gov (United States)

    Ishchenko, Alexander A.; Kulinich, Andrii V.; Bondarev, Stanislav L.; Raichenok, Tamara F.

    2018-02-01

    Gas-phase absorption spectra of a merocyanine vinylogous series have been studied for the first time. In vapour, their long-wavelength absorption bands were found to be considerably shifted hypsochromically, broader, more symmetrical, less intense, and their vinylene shift much smaller than even in low-polarity n-hexane. This indicates that in the gas phase their electronic structure closely approaches the nonpolar polyene limiting structure. The TDDFT calculations of the long-wavelength electronic transitions in the studied merocyanines in vacuo demonstrated good-to-excellent correlation - depending on the functional used - with the obtained experimental data. For comparison, the solvent effects was accounted for using the polarizable continuum model (PCM) with n-hexane and ethanol as low-polarity and high-polarity media, and compared with the UV-Vis spectral data in these solvents. In this case, the discrepancy between theory and experiment was much greater, increasing at that with the polymethine chain length.

  6. Exciton-Dominated Core-Level Absorption Spectra of Hybrid Organic–Inorganic Lead Halide Perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Vorwerk, Christian [Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin, European Theoretical Spectroscopy; Hartmann, Claudia [Renewable Energy, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 14109 Berlin, Germany; Cocchi, Caterina [Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin, European Theoretical Spectroscopy; Sadoughi, Golnaz [Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom; Habisreutinger, Severin N. [Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom; Chemistry and Nanoscience Center, National Renewable Energy Laboratory (NREL), Golden, Colorado, United States; Félix, Roberto [Renewable Energy, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 14109 Berlin, Germany; Wilks, Regan G. [Renewable Energy, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 14109 Berlin, Germany; Energy Materials In-Situ Laboratory Berlin (EMIL), Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 12489 Berlin, Germany; Snaith, Henry J. [Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom; Bär, Marcus [Renewable Energy, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 14109 Berlin, Germany; Energy Materials In-Situ Laboratory Berlin (EMIL), Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 12489 Berlin, Germany; Draxl, Claudia [Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin, European Theoretical Spectroscopy

    2018-03-23

    In a combined theoretical and experimental work, we investigate X-ray absorption near-edge structure spectroscopy of the I L3 and the Pb M5 edges of the methylammonium lead iodide (MAPbI3) hybrid inorganic-organic perovskite and its binary phase PbI2. The absorption onsets are dominated by bound excitons with sizable binding energies of a few hundred millielectronvolts and pronounced anisotropy. The spectra of both materials exhibit remarkable similarities, suggesting that the fingerprints of core excitations in MAPbI3 are essentially given by its inorganic component, with negligible influence from the organic groups. The theoretical analysis complementing experimental observations provides the conceptual insights required for a full characterization of this complex material.

  7. Effect of Molar Concentration on Optical Absorption Spectra of ZnS:Mn Nanoparticles

    Directory of Open Access Journals (Sweden)

    Ravi Sharma

    2010-01-01

    Full Text Available The present paper reports the synthesis and characterization of luminescent nanocrystals of manganese doped zinc sulphide. Nanocrystals of zinc sulphide were prepared by chemical precipitation method using the solution of zinc chloride, sodium sulphide, manganese chloride and mercaptoethanol was used as the capping agent. It was found that change in the molar concentration changes the particle size. The particle size of such nanocrystals was measured using XRD pattern and it is found to be in between 3 nm – 5 nm. The blue-shift in absorption spectra was found with reducing size of the nanoparticles

  8. Water vapor absorption spectra of the upper atmosphere /45-185 per cm/

    Science.gov (United States)

    Augason, G. C.; Mord, A. J.; Witteborn, F. C.; Erickson, E. F.; Swift, C. D.; Caroff, L. J.; Kunz, L. W.

    1975-01-01

    The far IR nighttime absorption spectrum of the earth's atmosphere above 14 km is determined from observations of the bright moon. The spectra were obtained using a Michelson interferometer attached to a 30-cm telescope aboard a high-altitude jet aircraft. Comparison with a single-layer model atmosphere implies a vertical column of 3.4 plus or minus 0.4 microns of precipitable water on 30 August 1971 and 2.4 plus or minus 0.3 microns of precipitable water on 6 January 1972.-

  9. Absorption spectra of thin films of triple compounds in the system RbIPbI2

    International Nuclear Information System (INIS)

    Yunakova, O.N.; Miloslavskij, V.K.; Ksenofontova, E.V.; Kovalenko, E.N.

    2012-01-01

    A formation of compounds RbPbI 3 and Rb 4 PbI 6 in the system RbI-PbI 2 is revealed and their absorption spectra are investigated in an energy interval 2-6 eV and a temperatures range 90-500 K. It is established that the low-frequency exciton excitations are localized in PbI 6 4- structural elements of the crystal lattice, they are classified as excitons of intermediate coupling and are of a three-dimensional character in RbPbI 3 and a quasi-two-dimensional one in Rb 4 PbI 6 .

  10. Absorption Spectra of CuGaSe2 and CuInSe2 Semiconducting Nanoclusters

    KAUST Repository

    Mokkath, Junais Habeeb

    2015-10-01

    The structural and optical properties of the chalcopyrite CunGanSe2n and CunInnSe2n nanoclusters (n = 2, 4, 6, and 8) are investigated as a function of the size using a combination of basin-hopping global optimization and time-dependent density functional theory. Although the lowest energy structures are found to show almost random geometries, the band gaps and absorption spectra still are subject to systematic blue shifts for decreasing cluster size in the case of CunGanSe2n, indicating strong electron confinement. The applicability of the nanoclusters in photovoltaics is discussed. © 2015 American Chemical Society.

  11. The effect of dimethylsulfoxide on absorption and fluorescence spectra of aqueous solutions of acridine orange base.

    Science.gov (United States)

    Markarian, Shiraz A; Shahinyan, Gohar A

    2015-12-05

    The photophysical properties of aqueous solutions of acridine orange base (AOB) in wide concentration range of dimethylsulfoxide (DMSO) were studied by using absorption and steady-state fluorescence spectroscopy techniques at room temperature. The absorption spectrum of acridine orange in water shows two bands at 468 and 490 nm which were attributed to the dimer ((AOBH)2(2+)) and monomer (AOBH(+)) species respectively. In DMSO solution for the same AOB concentration only the basic form was detected with the band at 428 nm. The addition of DMSO to AOB aqueous solution leads to the decrease of absorption band at 490 nm and the new absorption band increases at 428 nm due to deprotonated (basic) form of AO and the first isosbestic point occurs at 450 nm. The evolution of isosbestic point reveals that an other equilibrium, due to the self-association of DMSO molecules takes place. From the steady-state fluorescence spectra Stokes shifts were calculated for AOB in aqueous and DMSO solutions. The addition of DMSO into the aqueous solution induced the enhancement in the fluorescence intensity of the dye compared to those in water. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Temperature-dependent mid-IR absorption spectra of gaseous hydrocarbons

    International Nuclear Information System (INIS)

    Klingbeil, Adam E.; Jeffries, Jay B.; Hanson, Ronald K.

    2007-01-01

    Quantitative mid-IR absorption spectra (2500-3400 cm -1 ) for 12 pure hydrocarbon compounds are measured at temperatures ranging from 25 to 500 deg. C using an FTIR spectrometer. The hydrocarbons studied are n-pentane, n-heptane, n-dodecane, 2,2,4-trimethyl-pentane (iso-octane), 2-methyl-butane, 2-methyl-pentane, 2,4,4-trimethyl-1-pentene, 2-methyl-2-butene, propene, toluene, m-xylene, and ethylbenzene. Room-temperature measurements of neat hydrocarbon vapor were made with an instrument resolution of both 0.1 and 1 cm -1 (FWHM) to confirm that the high-resolution setting was required only to resolve the propene absorption spectrum while the spectra of the other hydrocarbons could be resolved with 1 cm -1 resolution. High-resolution (0.1 cm -1 ), room-temperature measurements of neat hydrocarbons were made at low pressure (∼1 Torr, 133 Pa) and compared to measurements of hydrocarbon/N 2 mixtures at atmospheric pressure to verify that no pressure broadening could be observed over this pressure range. The temperature was varied between 25 and 500 o C for atmospheric-pressure measurements of hydrocarbon/N 2 mixtures (X hydrocarbon ∼0.06-1.5%) and it was found that the absorption cross section shows simple temperature-dependent behavior for a fixed wavelength over this temperature range. Comparisons with previous FTIR data over a limited temperature range and with high-resolution laser absorption data over a wide temperature range show good agreement

  13. Temperature-dependent mid-IR absorption spectra of gaseous hydrocarbons

    Science.gov (United States)

    Klingbeil, Adam E.; Jeffries, Jay B.; Hanson, Ronald K.

    2007-10-01

    Quantitative mid-IR absorption spectra (2500 3400 cm-1) for 12 pure hydrocarbon compounds are measured at temperatures ranging from 25 to 500 °C using an FTIR spectrometer. The hydrocarbons studied are n-pentane, n-heptane, n-dodecane, 2,2,4-trimethyl-pentane (iso-octane), 2-methyl-butane, 2-methyl-pentane, 2,4,4-trimethyl-1-pentene, 2-methyl-2-butene, propene, toluene, m-xylene, and ethylbenzene. Room-temperature measurements of neat hydrocarbon vapor were made with an instrument resolution of both 0.1 and 1 cm-1 (FWHM) to confirm that the high-resolution setting was required only to resolve the propene absorption spectrum while the spectra of the other hydrocarbons could be resolved with 1 cm-1 resolution. High-resolution (0.1 cm-1), room-temperature measurements of neat hydrocarbons were made at low pressure (˜1 Torr, 133 Pa) and compared to measurements of hydrocarbon/N2 mixtures at atmospheric pressure to verify that no pressure broadening could be observed over this pressure range. The temperature was varied between 25 and 500 °C for atmospheric-pressure measurements of hydrocarbon/N2 mixtures (Xhydrocarbon˜0.06 1.5%) and it was found that the absorption cross section shows simple temperature-dependent behavior for a fixed wavelength over this temperature range. Comparisons with previous FTIR data over a limited temperature range and with high-resolution laser absorption data over a wide temperature range show good agreement.

  14. Transient absorption and luminescence spectra of K9 glass at sub-damage site by ultraviolet laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Z., E-mail: namezhangzhen@126.com [Science and Technology on Plasma Physics Laboratory, Research Center of Laser Fusion (China); Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610000 (China); Huang, J.; Geng, F.; Zhou, X.Y. [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Feng, S.Q. [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610000 (China); Cheng, X.L., E-mail: chengxl@scu.edu.cn [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610000 (China); Jiang, X.D. [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Wu, W.D. [Science and Technology on Plasma Physics Laboratory, Research Center of Laser Fusion (China); Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610000 (China); Zheng, W.G.; Tang, Y.J. [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China)

    2014-01-01

    Highlights: • Transient absorption and luminescence spectra at sub-damage site of K9 glass by laser irradiation at 355 nm are presented. • As the energy density increases to 2.54 J/cm{sup 2}, the absorption intensity reaches to about 0.2. • The mechanism of two-photon ionization mainly plays a critical role at sub-damage site. • Intensity of Raman spectra is very high at low energy density and decreased with respect to high energy density. -- Abstract: Transient absorption and luminescence spectra at sub-damage site of K9 glass by laser irradiation at 355 nm are presented. The dependence of transient absorption on laser energy and number of pulses was investigated. As the energy density increases to 2.54 and 3.18 J/cm{sup 2}, the transient absorption intensity reaches to about 0.20 range from 400 to 480 nm. With the increase of number of pulses the process of residual absorption appears, which can be used to explain the fatigue effect of K9 glass. The defects in K9 glass were investigated by fluorescence and Raman spectra. The fluorescence band centered at about 410 nm is attributed to oxygen deficiency centers. The mechanism of two-photon ionization plays a critical role at sub-damage site. Compared to the Raman spectra of pristine site, intensity of Raman spectra is very high at a lower energy density, while it decreased at a higher energy density.

  15. Photoionization Modeling of Oxygen K Absorption in the Interstellar Medium:. [The Chandra Grating Spectra of XTE J1817-330

    Science.gov (United States)

    Gatuzz, E.; Garcia, J.; Mendoza, C.; Kallman, T. R.; Witthoeft, M.; Lohfink, A.; Bautista, M. A.; Palmeri, P.; Quinet, P.

    2013-01-01

    We present detailed analyses of oxygen K absorption in the interstellar medium (ISM) using four high-resolution Chandra spectra toward the X-ray low-mass binary XTE J1817-330. The 11-25 Angstrom broadband is described with a simple absorption model that takes into account the pile-up effect and results in an estimate of the hydrogen column density. The oxygen K-edge region (21-25 Angstroms) is fitted with the physical warmabs model, which is based on a photoionization model grid generated with the xstar code with the most up-to-date atomic database. This approach allows a benchmark of the atomic data which involves wavelength shifts of both the K lines and photoionization cross sections in order to fit the observed spectra accurately. As a result we obtain a column density of N(sub H) = 1.38 +/- 0.01 × 10(exp 21) cm(exp -2); an ionization parameter of log xi = -2.70 +/- 0.023; an oxygen abundance of A(sub O) = 0.689 (+0.015/-0.010); and ionization fractions of O(sub I)/O = 0.911, O(sub II)/O = 0.077, and O(sub III)/O = 0.012 that are in good agreement with results from previous studies. Since the oxygen abundance in warmabs is given relative to the solar standard of Grevesse & Sauval, a rescaling with the revision by Asplund et al. yields A(sub O) = 0.952(+0.020/-0.013), a value close to solar that reinforces the new standard.We identify several atomic absorption lines-K(alpha), K(beta), and K(gamma) in O(sub I) and O(sub II) and K(alpha) in O(sub III), O(sub VI), and O(sub VII)-the last two probably residing in the neighborhood of the source rather than in the ISM. This is the first firm detection of oxygen K resonances with principal quantum numbers n greater than 2 associated with ISM cold absorption.

  16. Photoionization Modeling of Oxygen K Absorption in the Interstellar Medium: The Chandra Grating Spectra of XTE J1817-330

    Science.gov (United States)

    Gatuzz, E.; Garcia, J.; Menodza, C.; Kallman, T. R.; Witthoeft, M.; Lohfink, A.; Bautista, M. A.; Palmeri, P.; Quinet, P.

    2013-01-01

    We present detailed analyses of oxygen K absorption in the interstellar medium (ISM) using four high-resolution Chandra spectra towards the X-ray low-mass binary XTE J1817-330. The 11-25 A broadband is described with a simple absorption model that takes into account the pileup effect and results in an estimate of the hydrogen column density. The oxygen K-edge region (21-25 A) is fitted with the physical warmabs model, which is based on a photoionization model grid generated with the XSTAR code with the most up-to-date atomic database. This approach allows a benchmark of the atomic data which involves wavelength shifts of both the K lines and photoionization cross sections in order to fit the observed spectra accurately. As a result we obtain: a column density of N(sub H) = 1.38 +/- 0.01 x 10(exp 21) cm(exp -2); ionization parameter of log xi = .2.70 +/- 0.023; oxygen abundance of A(sub O) = 0.689(exp +0.015./-0.010); and ionization fractions of O I/O = 0.911, O II/O = 0.077, and O III/O = 0.012 that are in good agreement with previous studies. Since the oxygen abundance in warmabs is given relative to the solar standard of Grevesse and Sauval (1998), a rescaling with the revision by Asplund et al. (2009) yields A(sub O) = 0.952(exp +0.020/-0.013, a value close to solar that reinforces the new standard. We identify several atomic absorption lines.K-alpha , K-beta, and K-gamma in O I and O II; and K-alpha in O III, O VI, and O VII--last two probably residing in the neighborhood of the source rather than in the ISM. This is the first firm detection of oxygen K resonances with principal quantum numbers n greater than 2 associated to ISM cold absorption.

  17. The absorption spectra of Pu(VI), -(V) and -(IV) produced electrochemically in carbonate-bicarbonate media

    International Nuclear Information System (INIS)

    Wester, D.W.; Sullivan, J.C.

    1983-01-01

    Absorption spectra in carbonate and bicarbonate media have been measured for various oxidation states of plutonium. The oxidation state of plutonium was adjusted electrochemically (Pu(VI)-V), Esub(f)=+0.11 V vs. SCE) to avoid contamination by redox reagents. In carbonate medium the spectra of Pu(VI) and Pu(V) showed marked differences from the spectra of the same oxidation state in acidic solutions. In bicarbonate the spectra of Pu(VI) and Pu(IV) also differed from the corresponding spectra in acidic media. Reduction to Pu(III) resulted in a precipitate in both carbonate and bicarbonate media. (author)

  18. Exploring the Time Evolution of Cool Metallic Absorption Features in UV Burst Spectra

    Science.gov (United States)

    Belmes, K.; Madsen, C. A.; DeLuca, E.

    2017-12-01

    UV bursts are compact brightenings in active regions that appear in UV images. They are identified through three spectroscopic features: (1) broadening and intensification of NUV/FUV emission lines, (2) the presence of optically thin Si IV emission, and (3) the presence of absorption features from cool metallic ions. Properties (2) and (3) imply that bursts exist at transition region temperatures (≥ 80,000 K) but are located in the cooler lower chromosphere ( 5,000 K). Their energetic and dynamical properties remain poorly constrained. Improving our understanding of this phenomena could help us further constrain the energetic and dynamical properties of the chromosphere, as well as give us insight into whether or not UV bursts contribute to chromospheric and/or coronal heating. We analyzed the time evolution of UV bursts using spectral data from the Interface Region Imaging Spectrograph (IRIS). We inspected Si IV 1393.8 Å line profiles for Ni II 1393.3 Å absorption features to look for signs of heating. Weakening of absorption features over time could indicate heating of the cool ions above the burst, implying that thermal energy from the burst could rapidly conduct upward through the chromosphere. To detect the spectral profiles corresponding to bursts, we applied a four-parameter Gaussian fit to every profile in each observation and took cuts in parameter space to isolate the bursts. We then manually reviewed the remaining profiles by looking for a statistically significant appearance of Ni II 1393.3 Å absorption. We quantified these absorption features by normalizing the Si IV 1393.8 Å emission profiles and measuring the maximum fractional extinction in each. Our preliminary results indicate that Ni II 1393.3 Å absorption may undergo a cycle of strengthening and weakening throughout a burst's lifetime. However, further investigation is needed for confirmation. This work is supported by the NSF-REU solar physics program at SAO, grant number AGS-1560313.

  19. Role of non-Condon vibronic coupling and conformation change on two-photon absorption spectra of green fluorescent protein

    Science.gov (United States)

    Ai, Yuejie; Tian, Guangjun; Luo, Yi

    2013-07-01

    Two-photon absorption spectra of green fluorescent proteins (GFPs) often show a blue-shift band compared to their conventional one-photon absorption spectra, which is an intriguing feature that has not been well understood. We present here a systematic study on one- and two-photon spectra of GFP chromophore by means of the density functional response theory and complete active space self-consistent field (CASSCF) methods. It shows that the popular density functional fails to provide correct vibrational progression for the spectra. The non-Condon vibronic coupling, through the localised intrinsic vibrational modes of the chromophore, is responsible for the blue-shift in the TPA spectra. The cis to trans isomerisation can be identified in high-resolution TPA spectra. Our calculations demonstrate that the high level ab initio multiconfigurational CASSCF method, rather than the conventional density functional theory is required for investigating the essential excited-state properties of the GFP chromophore.

  20. The importance of nuclear quantum effects in spectral line broadening of optical spectra and electrostatic properties in aromatic chromophores

    Science.gov (United States)

    Law, Y. K.; Hassanali, A. A.

    2018-03-01

    In this work, we examine the importance of nuclear quantum effects on capturing the line broadening and vibronic structure of optical spectra. We determine the absorption spectra of three aromatic molecules indole, pyridine, and benzene using time dependent density functional theory with several molecular dynamics sampling protocols: force-field based empirical potentials, ab initio simulations, and finally path-integrals for the inclusion of nuclear quantum effects. We show that the absorption spectrum for all these chromophores are similarly broadened in the presence of nuclear quantum effects regardless of the presence of hydrogen bond donor or acceptor groups. We also show that simulations incorporating nuclear quantum effects are able to reproduce the heterogeneous broadening of the absorption spectra even with empirical force fields. The spectral broadening associated with nuclear quantum effects can be accounted for by the broadened distribution of chromophore size as revealed by a particle in the box model. We also highlight the role that nuclear quantum effects have on the underlying electronic structure of aromatic molecules as probed by various electrostatic properties.

  1. Identifying Student and Teacher Difficulties in Interpreting Atomic Spectra Using a Quantum Model of Emission and Absorption of Radiation

    Science.gov (United States)

    Savall-Alemany, Francisco; Domènech-Blanco, Josep Lluís; Guisasola, Jenaro; Martínez-Torregrosa, Joaquín

    2016-01-01

    Our study sets out to identify the difficulties that high school students, teachers, and university students encounter when trying to explain atomic spectra. To do so, we identify the key concepts that any quantum model for the emission and absorption of electromagnetic radiation must include to account for the gas spectra and we then design two…

  2. Evidence from spectra of bright fireballs. [self absorption effects in meteor radiation

    Science.gov (United States)

    Ceplecha, Z.

    1973-01-01

    Spectral data with dispersions from 11 to 94 A/mm on 4 fireballs of actual brightness of -4 to -12 magnitude and with velocities of about 30 km/s at 70 to 80 km heights are used for studies of meteor radiation problems. The radiation of fireballs is found to be strongly affected by self absorption. But if the emission curve of growth is used for correction of the self absorption of Fe I lines, a great discrepancy between spectral data and efficiency data for total Fe I light is found. If one assumes that the self absorption is superposed on another effect, a decrease of the dimensions of the radiating volume with increasing lower potential, the spectral data on Fe I lines will be in agreement with the luminous efficiency of total Fe I meteor radiation. Formulas for emission curve of growth and Boltzmann distribution including this effect are derived. This effect is important for fireballs brighter than about -1 or -2 magnitude, while self absorption seems to be important even for fainter meteors.

  3. Gas phase UV and IR absorption spectra of CxF2x+1CHO (x=1-4)

    DEFF Research Database (Denmark)

    Hashikawa, Y; Kawasaki, M; Waterland, RL

    2004-01-01

    The UV and IR spectra of CxF2x+1 CHO (x = 1-4) were investigated using computational and experimental techniques. CxF2x+1CHO (x = 1-4) have broad UV absorption features centered at 300-310 nm. The maximum absorption cross-section increases significantly and shifts slightly to the red with increas...

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

    Science.gov (United States)

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

    1995-01-01

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

  5. Aprotic solvents effect on the UV-visible absorption spectra of bixin.

    Science.gov (United States)

    Rahmalia, Winda; Fabre, Jean-François; Usman, Thamrin; Mouloungui, Zéphirin

    2014-10-15

    We describe here the effects of aprotic solvents on the spectroscopic characteristics of bixin. Bixin was dissolved in dimethyl sulfoxide, acetone, dichloromethane, ethyl acetate, chloroform, dimethyl carbonate, cyclohexane and hexane, separately, and its spectra in the resulting solutions were determined by UV-visible spectrophotometry at normal pressure and room temperature. We analyzed the effect of aprotic solvents on λmax according to Onsager cavity model and Hansen theory, and determined the approximate absorption coefficient with the Beer-Lambert law. We found that the UV-visible absorption spectra of bixin were found to be solvent dependent. The S0→S2 transition energy of bixin in solution was dependent principally on the refractive index of the solvents and the bixin-solvent dispersion interaction. There was a small influence of the solvents dielectric constant, permanent dipole interaction and hydrogen bonding occurred between bixin and solvents. The absorbance of bixin in various solvents, with the exception of hexane, increased linearly with concentration. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Effect of absorption discontinuity on neutron spectra of water assemblies poisoned with non-1/V absorbers

    International Nuclear Information System (INIS)

    Gupta, I.J.; Trikha, S.K.

    1977-01-01

    Calculations are presented of the diffusion of thermal neutrons (2.5 x 10 -4 to 7 x 10 -1 eV) across an absorption discontinuity in a water assembly, consisting of pure water on one side and aqueous solutions of three different non-1/V absorbers on the other, which were obtained by solving the Boltzmann transport equation in the diffusion approximation using the multigroup formalism. The gradual appearance and disappearance of the depletion region in the neutron spectra (caused by the resonance absorption peaks at energies 0.096 and 0.179 eV for samarium and cadmium respectively), as one moves from the pure water assembly to the poisoned water assembly and vice versa, have also been studied. The minimum concentrations of Sm and Cd atoms in water for which the depletion region in the spectra just starts building up are found to be 60 x 10 18 Sm atom cm -3 and 125 x 10 18 Cd atom cm -3 respectively. However no such depletion region is observed in gadolinium-poisoned water assembly. At the boundary, the equilibrium neutron distribution gets disturbed and is re-established to the equilibrium distribution of the second medium at some distance from the interface. The diffusion lengths so calculated from the total neutron density curves are in good agreement with the experimental results of Goddard and Johnson (Nucl. Sci. Eng.; 37:127 (1969)) at various concentrations of Gd and Cd atoms in water. (author)

  7. Aprotic solvents effect on the UV-visible absorption spectra of bixin

    Science.gov (United States)

    Rahmalia, Winda; Fabre, Jean-François; Usman, Thamrin; Mouloungui, Zéphirin

    2014-10-01

    We describe here the effects of aprotic solvents on the spectroscopic characteristics of bixin. Bixin was dissolved in dimethyl sulfoxide, acetone, dichloromethane, ethyl acetate, chloroform, dimethyl carbonate, cyclohexane and hexane, separately, and its spectra in the resulting solutions were determined by UV-visible spectrophotometry at normal pressure and room temperature. We analyzed the effect of aprotic solvents on λmax according to Onsager cavity model and Hansen theory, and determined the approximate absorption coefficient with the Beer-Lambert law. We found that the UV-visible absorption spectra of bixin were found to be solvent dependent. The S0 → S2 transition energy of bixin in solution was dependent principally on the refractive index of the solvents and the bixin-solvent dispersion interaction. There was a small influence of the solvents dielectric constant, permanent dipole interaction and hydrogen bonding occurred between bixin and solvents. The absorbance of bixin in various solvents, with the exception of hexane, increased linearly with concentration.

  8. Fullerene-Based Photoactive Layers for Heterojunction Solar Cells: Structure, Absorption Spectra and Charge Transfer Process

    Directory of Open Access Journals (Sweden)

    Yuanzuo Li

    2014-12-01

    Full Text Available The electronic structure and optical absorption spectra of polymer APFO3, [70]PCBM/APFO3 and [60]PCBM/APFO3, were studied with density functional theory (DFT, and the vertical excitation energies were calculated within the framework of the time-dependent DFT (TD-DFT. Visualized charge difference density analysis can be used to label the charge density redistribution for individual fullerene and fullerene/polymer complexes. The results of current work indicate that there is a difference between [60]PCBM and [70]PCBM, and a new charge transfer process is observed. Meanwhile, for the fullerene/polymer complex, all calculations of the twenty excited states were analyzed to reveal all possible charge transfer processes in depth. We also estimated the electronic coupling matrix, reorganization and Gibbs free energy to further calculate the rates of the charge transfer and the recombination. Our results give a clear picture of the structure, absorption spectra, charge transfer (CT process and its influencing factors, and provide a theoretical guideline for designing further photoactive layers of solar cells.

  9. Metallic Line Doubling and van hoof Effect in the Spectra of the Variable Star RR Lyrae

    Science.gov (United States)

    Sefyani Lakrizi, Fouad; Benhida, Abdelmjid; Gillet, Denis; Mathias, phillipe; de France, Thibault; Benkhaldoun, Zouhair; Lazrek, Mohamed; Daassou, Ahmed

    2015-08-01

    The Oukaïmeden observatory is situated at an altitude of 2700m in the High Atlas mountain range, 78km south of Marrakech 7°52’52’’ west and 31°12’32’’ north. The quality of the sky is considered exceptional, not only for imaging but also for photometry. Indeed, the average measured seeing is of the order of 1 arc second which ensures high quality spectrum recording with a good signal-to-noise ratio. In this communication, we will present our observations of the phenomenon of metallic absorption lines, doubling in the spectra of the variable star RR Lyrae on Fe II (l4923.921 Å), as well as of sodium D lines. In emission, we observed the lines of hydrogen Hα, Hβ and Hγ with a very strong intensity (50 % above the continuum). We also observed the Van Hoof effect which consists of a difference between the radial velocity of the line of the Fe II (λ4923.921 Å) and that of the line Hβ. These observations were carried out with a small spectrograph of approximately 12000 resolution, installed on a 14 inch telescope, during the night of October 12th 2013. This date corresponded to the maximal phase of the Blazhko cycle. The doubling of the lines was interpreted by Schwarzschild on the basis of an atmosphere in two layers. Based on this interpretation we were able to measure the radial velocity of the shock wave deducted from the difference between both red and blue spectral components on the lines Hα of hydrogen, D of the sodium and the Fe II during the doubling of observed lines. The shock wave reached the maximal speed of 160 kms-1 so confirming the hypersonic regime to which atmosphere is submitted during this maximum phase of the Blazhko cycle. We will also present a comparison of our results with those obtained with high resolution spectrographs and thus confirm the validity of our results.

  10. Emission Line Spectra from Low-Density Laboratory Plasmas

    Science.gov (United States)

    Beiersdorfer, P.; Brown, G. V.; Drake, J. J.; Gu, M.-F.; Kahn, S. M.; Lepson, J. K.; Liedahl, D. A.; Mauche, C. W.; Savin, D. W.; Utter, S. B.; hide

    2000-01-01

    Using spectroscopic equipment optimized for laboratory astrophysics, we are performing systematic measurements of the line emission from astrophysically relevant ions in the wavelength band between 1 and 400 Angstroms important to X-ray missions such as Chandra, XMM, Astro-E, and EUVE. Obtained in a controlled laboratory setting at electron densities similar to those found in stellar coronae, the data are used to test spectral modeling codes for accuracy and completeness. Our effort includes the compilation of the iron L-shell emission lines from 6-18 Angstroms and the iron M-shell emission lines from 50-200 Angstroms. Many lines have been identified for the first time, and the fluxes from lines missing in the spectral modeling codes are assessed. Our measurements also assess the accuracy of line excitation calculations, including direct electron-impact excitation, dielectronic recombination, and resonance excitation. These measurements yield a calibration of specific diagnostic line ratios. Examples of our current measurements are given.

  11. The electronic absorption spectra of some acyl azides. Molecular orbital treatment

    Science.gov (United States)

    Abu-Eittah, Rafie H.; Mohamed, Adel A.; Farag, A. M.; Al Omar, Ahmed M.

    2008-06-01

    The electronic absorption spectra of benzoyl azide and its derivatives: p-methyl, p-methoxy, p-chloro and p-nitrobenzoyl azide were investigated in different solvents. The observed spectra differ basically from the electronic spectra of aryl azides or alkyl azides. Four intense π-π * transitions were observed in the accessible UV region of the spectrum of each of the studied compounds. The contribution of charge transfer configurations to the observed transitions is rather weak. Shift of band maximum with solvent polarity is minute. On the other hand, band intensity is highly dependent on the solvent used. The observed transitions are delocalized rather than localized ones as in the case with aryl and alkyl azides. The attachment of the C dbnd O group to the azide group in acyl azides has a significant effect on the electronic structure of the molecule. The arrangements as well as energies of the molecular orbitals are different in acyl azides from those in aryl azides. The first electronic transition in phenyl azide is at 276 nm, whereas that of bezoyle azide is at 251 nm. Ab initio molecular orbital calculations using both RHF/6-311G* and B3LYP/6-31+G * levels were carried out on the ground states of the studied compounds. The wave functions of the excited states were calculated using the CIS and the AM1-CI procedures.

  12. Plastocyanin conformation: an analysis of its near ultraviolet absorption and circular dichroic spectra

    International Nuclear Information System (INIS)

    Draheim, J.E.; Anderson, G.P.; Duane, J.W.; Gross, E.L.

    1986-01-01

    The near-ultraviolet absorption and circular dichroic spectra of plastocyanin are dependent upon the redox state, solution pH, and ammonium sulfate concentration. This dependency was observed in plastocyanin isolated from spinach, poplar, and lettuce. Removal of the copper atom also perturbed the near-ultraviolet spectra. Upon reduction there are increases in both extinction and ellipticity at 252 nm. Further increases at 252 nm were observed upon formation of apo plastocyanin eliminating charge transfer transitions as the cause. The spectral changes in the near-ultraviolet imply a flexible tertiary conformation for plastocyanin. There are at least two charge transfer transitions at ∼295-340 nm. One of these transitions is sensitive to low pH's and is attributed to the His 87 copper ligand. The redox state dependent changes observed in the near-ultraviolet spectra of plastocyanin are attenuated either by decreasing the pH to 5 or by increasing the ammonium sulfate concentration to 2.7 M. This attenuation cannot be easily explained by simple charge screening. Hydrophobic interactions probably play an important role in this phenomenon. The pH and redox state dependent conformational changes may play an important role in regulating electron transport

  13. Study of absorption spectra for alkali and alkaline earth metal salts in flameless atomic absorption spectrometry using a carbon tube atomizer

    International Nuclear Information System (INIS)

    Yasuda, Seiji; Kakiyama, Hitoo

    1975-01-01

    Absorption spectra of various salts such as alkali metal salts, alkaline earth dichlorides, and ammonium halides were investigated and absorptions of some molecular species produced in the carbon tube were identified. The aqueous solution (20 μl) containing 1.0 mg/ml of each salt was placed in the carbon tube atomizer and heated in a similar manner to usual flameless atomic absorption method. D 2 -lamp was used as a continuous light source and argon gas was employed as an inert sheath gas. The spectra were obtained over the range of wavelength 200 to 350 nm. When alkali halides were feeded, the absorption spectra agreed with those of alkali halide vapors. Therefore, in such cases vapors of the alkali halides were probably produced by the sublimation or vaporization in the atomizer. The spectra of alkali perchlorates were considered to be those of alkali chlorides produced by the pyrolysis of the perchlorates in the atomizer. The absorptions of alkaline earth chlorides below 250 nm were probably due to their gaseous states. Sulfur dioxide was found to be produced by the pyrolysis of alkali sulfates, bisulfates and sulfites in the atomizer, Alkali phosphates and pyrophosphates gave almost identical spectra below 300 nm. Gamma band spectrum of nitrogen monoxide was observed from 200 to 240 nm during ashing at bout 330 0 C for alkali nitrates and nitrites. Ammonia vapor was produced from ammonium halides during drying at about 170 0 C. Although the absorptions of alkali carbonates and hydroxides were almost undetectable, the same spectra as those of alkali halides were observed by the addition of ammonium halides to the solutions of alkali compounds. This shows that alkali halides are produced in the atomizer by the addition of halide ions. (auth.)

  14. PHOTOIONIZATION MODELING OF OXYGEN K ABSORPTION IN THE INTERSTELLAR MEDIUM: THE CHANDRA GRATING SPECTRA OF XTE J1817-330

    International Nuclear Information System (INIS)

    Gatuzz, E.; Mendoza, C.; García, J.; Lohfink, A.; Kallman, T. R.; Witthoeft, M.; Bautista, M. A.; Palmeri, P.; Quinet, P.

    2013-01-01

    We present detailed analyses of oxygen K absorption in the interstellar medium (ISM) using four high-resolution Chandra spectra toward the X-ray low-mass binary XTE J1817-330. The 11-25 Å broadband is described with a simple absorption model that takes into account the pile-up effect and results in an estimate of the hydrogen column density. The oxygen K-edge region (21-25 Å) is fitted with the physical warmabs model, which is based on a photoionization model grid generated with the XSTAR code with the most up-to-date atomic database. This approach allows a benchmark of the atomic data which involves wavelength shifts of both the K lines and photoionization cross sections in order to fit the observed spectra accurately. As a result we obtain a column density of N H = 1.38 ± 0.01 × 10 21 cm –2 ; an ionization parameter of log ξ = –2.70 ± 0.023; an oxygen abundance of A O = 0.689 +0.015 -0.010 ; and ionization fractions of O I/O = 0.911, O II/O = 0.077, and O III/O = 0.012 that are in good agreement with results from previous studies. Since the oxygen abundance in warmabs is given relative to the solar standard of Grevesse and Sauval, a rescaling with the revision by Asplund et al. yields A O =0.952 +0.020 -0.013 , a value close to solar that reinforces the new standard. We identify several atomic absorption lines—Kα, Kβ, and Kγ in O I and O II and Kα in O III, O VI, and O VII—the last two probably residing in the neighborhood of the source rather than in the ISM. This is the first firm detection of oxygen K resonances with principal quantum numbers n > 2 associated with ISM cold absorption.

  15. First Time Rapid and Accurate Detection of Massive Number of Metal Absorption Lines in the Early Universe Using Deep Neural Network

    Science.gov (United States)

    Zhao, Yinan; Ge, Jian; Yuan, Xiaoyong; Li, Xiaolin; Zhao, Tiffany; Wang, Cindy

    2018-01-01

    Metal absorption line systems in the distant quasar spectra have been used as one of the most powerful tools to probe gas content in the early Universe. The MgII λλ 2796, 2803 doublet is one of the most popular metal absorption lines and has been used to trace gas and global star formation at redshifts between ~0.5 to 2.5. In the past, machine learning algorithms have been used to detect absorption lines systems in the large sky survey, such as Principle Component Analysis, Gaussian Process and decision tree, but the overall detection process is not only complicated, but also time consuming. It usually takes a few months to go through the entire quasar spectral dataset from each of the Sloan Digital Sky Survey (SDSS) data release. In this work, we applied the deep neural network, or “ deep learning” algorithms, in the most recently SDSS DR14 quasar spectra and were able to randomly search 20000 quasar spectra and detect 2887 strong Mg II absorption features in just 9 seconds. Our detection algorithms were verified with previously released DR12 and DR7 data and published Mg II catalog and the detection accuracy is 90%. This is the first time that deep neural network has demonstrated its promising power in both speed and accuracy in replacing tedious, repetitive human work in searching for narrow absorption patterns in a big dataset. We will present our detection algorithms and also statistical results of the newly detected Mg II absorption lines.

  16. Absorption, phosphorescence and Raman spectra of IrQ(ppy){sub 2} organometallic compound

    Energy Technology Data Exchange (ETDEWEB)

    Polosan, Silviu, E-mail: silv@infim.ro [National Institute of Materials Physics, R-77125 Bucharest-Magurele (Romania); Ciobotaru, Iulia Corina [National Institute of Materials Physics, R-77125 Bucharest-Magurele (Romania); Tsuboi, Taiju [Kyoto Sangyo University, Kamigamo, Kita-ku, Kyoto 603-8555 (Japan)

    2015-07-15

    The absorption and photoluminescence (PL) spectra, PL decays, Raman spectrum, cyclic voltammetry (CV) and nuclear magnetic resonance of heteroleptic Ir-compound IrQ(ppy){sub 2} compound with two phenylpyridine (ppy) ligands and one quinoline (Q) ligand have been investigated experimentally and theoretically. Two very weak absorption bands due to the transitions to the triplet states are found at about 560 and 595 nm in IrQ(ppy){sub 2} doped in CH{sub 2}Cl{sub 2} solution. IrQ(ppy){sub 2} exhibits a dual emission of red and green phosphorescence bands. The red emission intensity is much higher than the green one in IrQ(ppy){sub 2} powder, but much lower than the green one in lightly IrQ(ppy){sub 2}-doped CH{sub 2}Cl{sub 2} solution and PMMA film. The intensity ratio of the red emission to the green emission, however, is observed to increase with increasing the IrQ(ppy){sub 2} concentration in CH{sub 2}Cl{sub 2} solution and PMMA film. The enhancement of the red emission is suggested to be caused by the Forester energy transfer from Ir-ppy component to Ir–Q components between two neighboring IrQ(ppy){sub 2} molecules. The HOMO energy is estimated to be −4.865 eV from the CV measurement, which is close to the HOMO energy of −4.844 eV calculated using the time dependent density function theory (TD-DFT). The LUMO energy is estimated as −2.856 eV from the HOMO energy and the long-wavelength absorption edge found at 617 nm in the absorption spectrum. The absorption spectrum of IrQ(ppy){sub 2} is calculated by the TD-DFT. Discussion is given on a deviation of the calculated spectrum from the measured spectrum. - Graphical abstract: Display Omitted - Highlights: • IrQ(ppy){sub 2} has red and green emissions of different ratio between film and solution. • Intensity ratio of red to green emissions increases with IrQ(ppy){sub 2} concentration. • Enhancement of red emission is due to energy transfer in two neighboring IrQ(ppy){sub 2}. • Lowest-energy absorption

  17. Extent and structure of intervening absorbers from absorption lines redshifted on quasar emission lines

    Science.gov (United States)

    Bergeron, J.; Boissé, P.

    2017-07-01

    Aims: We wish to study the extent and sub-parsec spatial structure of intervening quasar absorbers, mainly those involving cold neutral and molecular gas. Methods: We have selected quasar absorption systems with high spectral resolution and a good signal-to-noise ratio data, with some of their lines falling on quasar emission features. By investigating the consistency of absorption profiles seen for lines formed either against the quasar continuum source or on the much more extended (Lyα-N v, C iv or Lyβ-O vi) emission line region (ELR), we can probe the extent and structure of the foreground absorber over the extent of the ELR ( 0.3-1 pc). The spatial covering analysis provides constraints on the transverse size of the absorber and thus is complementary to variability or photoionisation modelling studies, which yield information on the absorber size along the line of sight. The methods we used to identify spatial covering or structure effects involve line profile fitting and curve-of-growth analysis. Results: We have detected three absorbers with unambiguous non-uniformity effects in neutral gas. For the extreme case of the Fe I absorber at zabs = 0.45206 towards HE 0001-2340, we derive a coverage factor of the ELR of at most 0.10 and possibly very close to zero; this implies an overall absorber size no larger than 0.06 pc. For the zabs = 2.41837 C I absorber towards QSO J1439+1117, absorption is significantly stronger towards the ELR than towards the continuum source in several C I and C I⋆ velocity components, pointing to spatial variations of their column densities of about a factor of two and to structures at the 100 au-0.1 pc scale. The other systems with firm or possible effects can be described in terms of a partial covering of the ELR, with coverage factors in the range 0.7-1. The overall results for cold neutral absorbers imply a transverse extent of about five times the ELR size or smaller, which is consistent with other known constraints. Although

  18. Ly(alpha) emission and absorption features in the spectra of galaxies

    Science.gov (United States)

    Chen, W. L.; Neufeld, David A.

    1994-01-01

    The combined effects of interstellar dust absorption and of scattering by hydrogen atoms may give rise to a Ly(alpha) spectral feature of negative equivalent width, as has been observed in several star-forming galaxies. By considering the transfer of Ly(alpha) line radiation and of neighboring stellar continuum radiation within a dusty galaxy, we find that dust absorption has three effects: (1) it reduces the apparent ultraviolet continuum luminosity at all wavelengths; (2) it preferentially decreases the apparent Ly(alpha) line luminosity from H II regions; and (3) it creates an 'attenuation feature' in the continuum spectrum -- centered at the Ly(alpha) rest frequency -- which occurs because the attenuation of the stellar continuum radiation increases as the Ly(alpha) rest frequency is approached, due to the effects of scattering by hydrogen atoms. For plausible values of the galactic dust content and of the disk thickness, these effects can lead to a negative net Ly(alpha) equivalent width, even for galaxies in which the unattenuated spectrum would show a strong Ly(alpha) emission line.

  19. Study on the man-operator characteristics in the peak identification problem in line spectra

    International Nuclear Information System (INIS)

    Gopych, P.M.; Sorokin, V.I.; Sotnikov, V.V.

    1992-01-01

    ATOS program complex (automatical test spectra processing) realizing all stages of investigation necessary to obtain qualitative characteristics of the man-operator in the peak identification problem is developed. Qualitative characteristics of identitication ion quality of peaks by operators searching for peaks in line spectra are determined due to simulation experiment. It is shown, that for trained operators reference possibility of false detection of peaks is equal to F=0.012±0.004, while for untrained ones - F≅0.3. Comparison of results with analogous data on on-line programs for identification of peaks in γ-spectra is conducted

  20. The absorption- and luminescence spectra of Mn3+ in beryl and vesuvianite

    Science.gov (United States)

    Czaja, Maria; Lisiecki, Radosław; Chrobak, Artur; Sitko, Rafał; Mazurak, Zbigniew

    2017-12-01

    The electron absorption-, photoluminescence- and electron paramagnetic-resonance spectra of Mn3+ in red beryl from Wah Wah Mountains (Utah USA) and of pink- and purple vesuvianite from Jeffrey Mine (Asbestos, Canada) were measured at room- and low temperatures. The crystal field stabilization energies are equal to 130.9 kJ/mol for the red beryl, and 151.5-158.0 and 168.0 kJ/mol for for the pink- and the purple vesuvianite, respectively. The red photoluminescence of Mn3+ was not intensive either at room- or at low temperatures. The high Mn content in the crystals caused the emergence of an additional emission band and short photoluminescence-decay lifetimes. The latter are only 183 μs for beryl and 17 μs for vesuvianite.

  1. Specific absorption spectra of hemoglobin at different PO2 levels: potential noninvasive method to detect PO2 in tissues.

    Science.gov (United States)

    Liu, Peipei; Zhu, Zhirong; Zeng, Changchun; Nie, Guang

    2012-12-01

    Hemoglobin (Hb), as one of main components of blood, has a unique quaternary structure. Its release of oxygen is controlled by oxygen partial pressure (PO2). We investigate the specific spectroscopic changes in Hb under different PO2 levels to optimize clinical methods of measuring tissue PO2. The transmissivity of Hb under different PO2 levels is measured with a UV/Vis fiber optic spectrometer. Its plotted absorption spectral curve shows two high absorption peaks at 540 and 576 nm and an absorption valley at 560 nm when PO2 is higher than 100 mm Hg. The two high absorption peaks decrease gradually with a decrease in PO2, whereas the absorption valley at 560 nm increases. When PO2 decreases to approximately 0 mm Hg, the two high absorption peaks disappear completely, while the absorption valley has a hypochromic shift (8 to 10 nm) and forms a specific high absorption peak at approximately 550 nm. The same phenomena can be observed in visible reflectance spectra of finger-tip microcirculation. Specific changes in extinction coefficient and absorption spectra of Hb occur along with variations in PO2, which could be used to explain pathological changes caused by tissue hypoxia and for early detection of oxygen deficiency diseases in clinical monitoring.

  2. Shock-reflected electrons and X-ray line spectra

    Czech Academy of Sciences Publication Activity Database

    Dzifčáková, Elena; Vandas, Marek; Karlický, Marian

    2017-01-01

    Roč. 603, July (2017), A17/1-A17/8 E-ISSN 1432-0746 R&D Projects: GA ČR(CZ) GA17-16447S; GA ČR GAP209/12/0103; GA ČR(CZ) GA14-19376S; GA ČR(CZ) GA17-06065S; GA ČR GA15-17490S; GA ČR(CZ) GA16-13277S Institutional support: RVO:67985815 Keywords : Sun * flares * line formation Subject RIV: BN - Astronomy , Celestial Mechanics, Astrophysics OBOR OECD: Astronomy (including astrophysics,space science) Impact factor: 5.014, year: 2016

  3. Source brightness fluctuation correction of solar absorption fourier transform mid infrared spectra

    Directory of Open Access Journals (Sweden)

    T. Ridder

    2011-06-01

    Full Text Available The precision and accuracy of trace gas observations using solar absorption Fourier Transform infrared spectrometry depend on the stability of the light source. Fluctuations in the source brightness, however, cannot always be avoided. Current correction schemes, which calculate a corrected interferogram as the ratio of the raw DC interferogram and a smoothed DC interferogram, are applicable only to near infrared measurements. Spectra in the mid infrared spectral region below 2000 cm−1 are generally considered uncorrectable, if they are measured with a MCT detector. Such measurements introduce an unknown offset to MCT interferograms, which prevents the established source brightness fluctuation correction. This problem can be overcome by a determination of the offset using the modulation efficiency of the instrument. With known modulation efficiency the offset can be calculated, and the source brightness correction can be performed on the basis of offset-corrected interferograms. We present a source brightness fluctuation correction method which performs the smoothing of the raw DC interferogram in the interferogram domain by an application of a running mean instead of high-pass filtering the corresponding spectrum after Fourier transformation of the raw DC interferogram. This smoothing can be performed with the onboard software of commercial instruments. The improvement of MCT spectra and subsequent ozone profile and total column retrievals is demonstrated. Application to InSb interferograms in the near infrared spectral region proves the equivalence with the established correction scheme.

  4. Investigation of absorption spectra of Gafchromic EBT2 film's components and their impact on UVR dosimetry

    Science.gov (United States)

    Aydarous, Abdulkadir

    2016-05-01

    The absorption spectra of the EBT2 film's components were investigated in conjunction with its use for UVA dosimetry. The polyester (topside) and adhesive layers of the EBT2 film have been gently removed. Gafchromic™ EBT2 films with and without the protected layers (polyester and adhesive) were exposed to UVR of 365 nm for different durations. Thereafter, the UV-visible spectra were measured using a UV-visible spectrophotometer (Model Spectro Dual Split Beam, UVS-2700). Films were digitized using a Nikon CanoScan 9000F Mark II flatbed scanner. The dosimetric characteristics including film's uniformity, reproducibility and post-irradiation development were investigated. The color development of EBT2 and new modified EBT2 (EBT2-M) films irradiated with UVA was relatively stable (less than 1%) immediately after exposure. Based on this study, the sensitivity of EBT2 to UVR with wavelength between ~350 nm and ~390 nm can significantly be enhanced if the adhesive layer (~25 μm) is removed. The polyester layer plays almost no part on absorbing UVR with wavelength between ~320 nm and ~390 nm. Furthermore, various sensitivities for the EBT2-M film has been established depending on the wavelength of analysis.

  5. Total Absorption Spectroscopy of Fission Fragments Relevant for Reactor Antineutrino Spectra and Decay Heat Calculations

    Directory of Open Access Journals (Sweden)

    Porta A.

    2016-01-01

    Full Text Available Beta decay of fission products is at the origin of decay heat and antineutrino emission in nuclear reactors. Decay heat represents about 7% of the reactor power during operation and strongly impacts reactor safety. Reactor antineutrino detection is used in several fundamental neutrino physics experiments and it can also be used for reactor monitoring and non-proliferation purposes. 92,93Rb are two fission products of importance in reactor antineutrino spectra and decay heat, but their β-decay properties are not well known. New measurements of 92,93Rb β-decay properties have been performed at the IGISOL facility (Jyväskylä, Finland using Total Absorption Spectroscopy (TAS. TAS is complementary to techniques based on Germanium detectors. It implies the use of a calorimeter to measure the total gamma intensity de-exciting each level in the daughter nucleus providing a direct measurement of the beta feeding. In these proceedings we present preliminary results for 93Rb, our measured beta feedings for 92Rb and we show the impact of these results on reactor antineutrino spectra and decay heat calculations.

  6. Time-Dependent Density Functional Calculations of Ligand K-Edge X-Ray Absorption Spectra

    Energy Technology Data Exchange (ETDEWEB)

    DeBeer George, S.; /SLAC, SSRL; Petrenko, T.; Neese, F.

    2007-07-10

    X-ray absorption spectra (XAS) at the Cl and S K edge and Mo L edge have been calculated at the TDDFT level for a series of dioxomolybdenum complexes LMoO{sub 2}X (L = hydrotris(3,5-dimethyl-1-pyrazolyl)borate, X = Cl, SCH{sub 2}Ph, OPh), which play an important role in modeling the catalytic cycle of the sulfite oxidase enzyme. Also, the XAS spectra of model molecules of the Mo complexes have been simulated and interpreted in terms of the Mo 4d orbital splitting, in order to find possible correlations with the spectral pattern of the complexes. Comparison with the available experimental data allows us to assess the performances of the present computational scheme to describe the core excitations in large bioinorganic systems. The theoretical interpretation of the spectral features of both the metal and ligand core excitations in terms of the oscillator strength distribution provides important insight into the covalency of the metal-ligand bond.

  7. DFT study of the effect of substituents on the absorption and emission spectra of Indigo

    Directory of Open Access Journals (Sweden)

    Cervantes-Navarro Francisco

    2012-07-01

    Full Text Available Abstract Background Theoretical analyses of the indigo dye molecule and its derivatives with Chlorine (Cl, Sulfur (S, Selenium (Se and Bromine (Br substituents, as well as an analysis of the Hemi-Indigo molecule, were performed using the Gaussian 03 software package. Results Calculations were performed based on the framework of density functional theory (DFT with the Becke 3- parameter-Lee-Yang-Parr (B3LYP functional, where the 6-31 G(d,p basis set was employed. The configuration interaction singles (CIS method with the same basis set was employed for the analysis of excited states and for the acquisition of the emission spectra. Conclusions The presented absorption and emission spectra were affected by the substitution position. When a hydrogen atom of the molecule was substituted by Cl or Br, practically no change in the absorbed and emitted energies relative to those of the indigo molecule were observed; however, when N was substituted by S or Se, the absorbed and emitted energies increased.

  8. Computing the Absorption and Emission Spectra of 5-Methylcytidine in Different Solvents: A Test-Case for Different Solvation Models.

    Science.gov (United States)

    Martínez-Fernández, L; Pepino, A J; Segarra-Martí, J; Banyasz, A; Garavelli, M; Improta, R

    2016-09-13

    The optical spectra of 5-methylcytidine in three different solvents (tetrahydrofuran, acetonitrile, and water) is measured, showing that both the absorption and the emission maximum in water are significantly blue-shifted (0.08 eV). The absorption spectra are simulated based on CAM-B3LYP/TD-DFT calculations but including solvent effects with three different approaches: (i) a hybrid implicit/explicit full quantum mechanical approach, (ii) a mixed QM/MM static approach, and (iii) a QM/MM method exploiting the structures issuing from molecular dynamics classical simulations. Ab-initio Molecular dynamics simulations based on CAM-B3LYP functionals have also been performed. The adopted approaches all reproduce the main features of the experimental spectra, giving insights on the chemical-physical effects responsible for the solvent shifts in the spectra of 5-methylcytidine and providing the basis for discussing advantages and limitations of the adopted solvation models.

  9. Ab initio calculations of optical absorption spectra: solution of the Bethe-Salpeter equation within density matrix perturbation theory.

    Science.gov (United States)

    Rocca, Dario; Lu, Deyu; Galli, Giulia

    2010-10-28

    We describe an ab initio approach to compute the optical absorption spectra of molecules and solids, which is suitable for the study of large systems and gives access to spectra within a wide energy range. In this approach, the quantum Liouville equation is solved iteratively within first order perturbation theory, with a Hamiltonian containing a static self-energy operator. This procedure is equivalent to solving the statically screened Bethe-Salpeter equation. Explicit calculations of single particle excited states and inversion of dielectric matrices are avoided using techniques based on density functional perturbation theory. In this way, full absorption spectra may be obtained with a computational workload comparable to ground state Hartree-Fock calculations. We present results for small molecules, for the spectra of a 1 nm Si cluster in a wide energy range (20 eV), and for a dipeptide exhibiting charge transfer excitations.

  10. Artifact suppression in electron paramagnetic resonance imaging of 14N- and 15N-labeled nitroxyl radicals with asymmetric absorption spectra

    Science.gov (United States)

    Takahashi, Wataru; Miyake, Yusuke; Hirata, Hiroshi

    2014-10-01

    This article describes an improved method for suppressing image artifacts in the visualization of 14N- and 15N-labeled nitroxyl radicals in a single image scan using electron paramagnetic resonance (EPR). The purpose of this work was to solve the problem of asymmetric EPR absorption spectra in spectral processing. A hybrid function of Gaussian and Lorentzian lineshapes was used to perform spectral line-fitting to successfully separate the two kinds of nitroxyl radicals. This approach can process the asymmetric EPR absorption spectra of the nitroxyl radicals being measured, and can suppress image artifacts due to spectral asymmetry. With this improved visualization method and a 750-MHz continuous-wave EPR imager, a temporal change in the distributions of a two-phase paraffin oil and water/glycerin solution system was visualized using lipophilic and hydrophilic nitroxyl radicals, i.e., 2-(14-carboxytetradecyl)-2-ethyl-4,4-dimethyl-3-oxazolidinyloxy (16-DOXYL stearic acid) and 4-hydroxyl-2,2,6,6-tetramethylpiperidine-d17-1-15N-1-oxyl (TEMPOL-d17-15N). The results of the two-phase separation experiment verified that reasonable artifact suppression could be achieved by the present method that deals with asymmetric absorption spectra in the EPR imaging of 14N- and 15N-labeled nitroxyl radicals.

  11. Equilibrium Structures and Absorption Spectra for SixOy-nH2O Molecular Clusters using Density Functional Theory

    Science.gov (United States)

    2017-05-04

    Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/6390--17-9723 Equilibrium Structures and Absorption Spectra for SixOy-nH2O Molecular...19b. TELEPHONE NUMBER (include area code) b. ABSTRACT c. THIS PAGE 18. NUMBER OF PAGES 17. LIMITATION OF ABSTRACT Equilibrium Structures and...1 Calculation of Absorption Spectra using DFT ……………………………………………..…..….2 DFT Calculation of Equilibrium

  12. Nanometer-scale local probing of X-ray absorption spectra of Co/Pt multilayer film

    Science.gov (United States)

    Quach, Duy-Truong; Pham, Duc-Thang; Handoko, Djati; Shim, Je-Ho; Eon Kim, Dong; Lee, Kyung-Min; Jeong, Jong-Ryul; Kim, Namdong; Shin, Hyun-Joon; Kim, Dong-Hyun

    2018-03-01

    We report our local X-ray absorption spectra (XAS) measurement mapping for a Co/Pt multilayer using scanning transmission microscopy with 25-nm spatial resolution and 0.1-eV spectral resolution. We have systematically analyzed the two-dimensional XAS intensity variation over the corresponding magnetic domain patterns, revealing a XAS profile across the magnetic domain wall as well as the simultaneous high-throughput measurement of local XAS spectra.

  13. UV absorption spectra and kinetics for alkyl and alkyl peroxy radicals originating from di-tert-butyl ether

    DEFF Research Database (Denmark)

    Nielsen, O.J.; Sehested, J.; Langer, S.

    1995-01-01

    Alkyl, (CH3)(3)COC(CH3)(2)CH2, and alkyl peroxy, (CH3)(3)COC(CH3)(2)CH2O2, radicals from di-tert-butyl ether (DTBE), have been studied in the gas phase at 296 K. A pulse radiolysis UV absorption technique was used to measure the spectra and kinetics. Absorption cross sections were quantified over...

  14. Reddening and He i{sup ∗} λ 10830 Absorption Lines in Three Narrow-line Seyfert 1 Galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Shaohua; Zhou, Hongyan; Shi, Xiheng; Pan, Xiang; Ji, Tuo; Jiang, Peng; Wang, Shufen [Polar Research Institute of China, 451 Jinqiao Road, Shanghai, 200136 (China); Liu, Wenjuan [Key Laboratory for the Structure and Evolution of Celestial Objects, Yunnan Observatories, Chinese Academy of Sciences, Kunming, Yunnan 650011 (China); Jiang, Ning, E-mail: zhangshaohua@pric.org.cn, E-mail: zhouhongyan@pric.org.cn [Key Laboratory for Researches in Galaxies and Cosmology, Department of Astronomy, University of Sciences and Technology of China, Chinese Academy of Sciences, Hefei, Anhui, 230026 (China)

    2017-08-20

    We report the detection of heavy reddening and the He i* λ 10830 absorption lines at the active galactic nucleus (AGN) redshift in three narrow-line Seyfert 1 galaxies: SDSS J091848.61+211717.0, SDSS J111354.66+124439.0, and SDSS J122749.13+321458.9. They exhibit very red optical to near-infrared colors, narrow Balmer/Paschen broad emission lines and He i* λ 10830 absorption lines. The ultraviolet-optical-infrared nucleus continua are reddened by the SMC extinction law of E ( B − V ) ∼ 0.74, 1.17, and 1.24 mag for three objects, which are highly consistent with the values obtained from the broad-line Balmer decrements, but larger than those of narrow emission lines. The reddening analysis suggests that the extinction dust simultaneously obscures the accretion disk, the broad emission-line region, and the hot dust from the inner edge of the torus. It is possible that the dust obscuring the AGN structures is the dusty torus itself. Furthermore, the Cloudy analysis of the He i* λ 10830 absorption lines proposes the distance of the absorption materials to be the extend scale of the torus, which greatly increases probabilities of the obscure and absorption materials being the dusty torus.

  15. The manifestation of optical centers in UV-Vis absorption and luminescence spectra of white blood human cells

    Science.gov (United States)

    Terent'yeva, Yu G.; Yashchuk, V. M.; Zaika, L. A.; Snitserova, O. M.; Losytsky, M. Yu

    2016-12-01

    A white blood human cells spectral investigation is presented. The aim of this series of experiments was to obtain and analyze the absorption and luminescence (fluorescence and phosphorescence) spectra at room temperature and at 78 K of newly isolated white blood human cells and their organelles. As a result the optical centers and possible biochemical components that form the studied spectra where identified. Also the differences between the spectra of abnormal cells (B-cell chronic lymphocytic leukemia BCLL) and normal ones were studied for the whole cells and individual organelles.

  16. The effects of solvents and structure on the electronic absorption spectra of the isomeric pyridine carboxylic acid N-oxides

    Directory of Open Access Journals (Sweden)

    Drmanić Saša Ž.

    2013-01-01

    Full Text Available The ultraviolet absorption spectra of the carboxyl group of three isomeric pyridine carboxylic acids N-oxides (picolinic acid N-oxide, nicotinic acid N-oxide and isonicotinic acid N-oxide were determined in fourteen solvents in the wavelength range from 200 to 400 nm. The position of the absorption maxima (λmax of the examined acids showed that the ultraviolet absorption maximum wavelengths of picolinic acid N-oxide are the shortest, and those of isonicotinic acid N-oxide acid are the longest. In order to analyze the solvent effect on the obtained absorption spectra, the ultraviolet absorption frequencies of the electronic transitions in the carboxylic group of the examined acids were correlated using a total solvatochromic equation of the form max = v0 + sπ + aα+ bβ, where υmax is the absorption frequency (1/λmax, p is a measure of the solvent polarity, β represents the scale of solvent hydrogen bond acceptor basicities and α represent the scale of solvent hydrogen bond donor acidities. The correlation of the spectroscopic data was carried out by means of multiple linear regression analysis. The solvent effects on the ultraviolet absorption maximums of the examined acids were discussed.

  17. Detection of O4 absorption around 328 and 419 nm in measured atmospheric absorption spectra

    Directory of Open Access Journals (Sweden)

    J. Lampel

    2018-02-01

    Full Text Available Retrieving the column of an absorbing trace gas from spectral data requires that all absorbers in the corresponding wavelength range are sufficiently well known. This is especially important for the retrieval of weak absorbers, whose absorptions are often in the 10−4 range. Previous publications on the absorptions of the oxygen dimer O2–O2 (or short: O4 list absorption peaks at 328 and 419 nm, for which no spectrally resolved literature cross sections are available. As these absorptions potentially influence the spectral retrieval of various trace gases, such as HCHO, BrO, OClO and IO, their shape and magnitude need to be quantified. We assume that the shape of the absorption peaks at 328 and 419 nm can be approximated by their respective neighbouring absorption peaks. Using this approach we obtain estimates for the wavelength of the absorption and its magnitude. Using long-path differential optical absorption spectroscopy (LP-DOAS observations and multi-axis DOAS (MAX-DOAS observations, we estimate the peak absorption cross sections of O4 to be (1.96  ±  0.20 × 10−47 cm5 molec−2 and determine the wavelength of its maximum at 328.59  ±  0.15 nm. For the absorption at 419.13  ±  0.42 nm a peak O4 cross-section value is determined to be (5.0  ±  3.5 × 10−48 cm5 molec−2.

  18. Emission Lines in the Near-infrared Spectra of the Infrared Quintuplet Stars in the Galactic Center

    Energy Technology Data Exchange (ETDEWEB)

    Najarro, F. [Departamento de Astrofísica, Centro de Astrobiología (CSIC-INTA), Ctra. Torrejón a Ajalvir km 4, E-28850 Torrejón de Ardoz (Spain); Geballe, T. R. [Gemini Observatory, 670 North A’ohoku Place, Hilo, HI 96720 (United States); Figer, D. F. [Center for Detectors, Rochester Institute of Technology, 74 Lomb Memorial Drive, Rochester, NY 14623 (United States); Fuente, D. de la [Instituto de Astronomía, Unidad Académica en Ensenada, Universidad Nacional Autónoma de México, Ensenada 22860, México (Mexico)

    2017-08-20

    We report the detection of a number of emission lines in the 1.0–2.4 μ m spectra of four of the five bright-infrared dust-embedded stars at the center of the Galactic center’s (GC) Quintuplet Cluster. Spectroscopy of the central stars of these objects is hampered not only by the large interstellar extinction that obscures all of the objects in the GC, but also by the large amounts of warm circumstellar dust surrounding each of the five stars. The pinwheel morphologies of the dust observed previously around two of them are indicative of Wolf–Rayet colliding wind binaries; however, infrared spectra of each of the five have until now revealed only dust continua steeply rising to long wavelengths and absorption lines and bands from interstellar gas and dust. The emission lines detected, from ionized carbon and from helium, are broad and confirm that the objects are dusty late-type carbon Wolf–Rayet stars.

  19. C IV BROAD ABSORPTION LINE ACCELERATION IN SLOAN DIGITAL SKY SURVEY QUASARS

    Energy Technology Data Exchange (ETDEWEB)

    Grier, C. J.; Brandt, W. N.; Trump, J. R.; Schneider, D. P.; Sun, M.; Beatty, T. G. [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States); Hall, P. B. [Department of Physics and Astronomy, York University, Toronto, ON M3J 1P3 (Canada); Filiz Ak, N. [Faculty of Sciences, Department of Astronomy and Space Sciences, Erciyes University, 38039 Kayseri (Turkey); Anderson, S. F. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Green, Paul J. [Harvard Smithsonian Center for Astrophysics, 60 Garden St, Cambridge, MA 02138 (United States); Vivek, M.; Brownstein, Joel R. [Department of Physics and Astronomy, University of Utah, 115 S. 1400 E., Salt Lake City, UT 84112 (United States); Roman-Lopes, Alexandre, E-mail: grier@psu.edu [Departamento de Fisica, Facultad de Ciencias, Universidad de La Serena, Cisternas 1200, La Serena (Chile)

    2016-06-20

    We present results from the largest systematic investigation of broad absorption line (BAL) acceleration to date. We use spectra of 140 quasars from three Sloan Digital Sky Survey programs to search for global velocity offsets in BALs over timescales of ≈2.5–5.5 years in the quasar rest frame. We carefully select acceleration candidates by requiring monolithic velocity shifts over the entire BAL trough, avoiding BALs with velocity shifts that might be caused by profile variability. The C iv BALs of two quasars show velocity shifts consistent with the expected signatures of BAL acceleration, and the BAL of one quasar shows a velocity-shift signature of deceleration. In our two acceleration candidates, we see evidence that the magnitude of the acceleration is not constant over time; the magnitudes of the change in acceleration for both acceleration candidates are difficult to produce with a standard disk-wind model or via geometric projection effects. We measure upper limits to acceleration and deceleration for 76 additional BAL troughs and find that the majority of BALs are stable to within about 3% of their mean velocities. The lack of widespread acceleration/deceleration could indicate that the gas producing most BALs is located at large radii from the central black hole and/or is not currently strongly interacting with ambient material within the host galaxy along our line of sight.

  20. Transient absorption and luminescence spectra of K9 glass at sub-damage site by ultraviolet laser irradiation

    Science.gov (United States)

    Zhang, Z.; Huang, J.; Geng, F.; Zhou, X. Y.; Feng, S. Q.; Cheng, X. L.; Jiang, X. D.; Wu, W. D.; Zheng, W. G.; Tang, Y. J.

    2014-01-01

    Transient absorption and luminescence spectra at sub-damage site of K9 glass by laser irradiation at 355 nm are presented. The dependence of transient absorption on laser energy and number of pulses was investigated. As the energy density increases to 2.54 and 3.18 J/cm2, the transient absorption intensity reaches to about 0.20 range from 400 to 480 nm. With the increase of number of pulses the process of residual absorption appears, which can be used to explain the fatigue effect of K9 glass. The defects in K9 glass were investigated by fluorescence and Raman spectra. The fluorescence band centered at about 410 nm is attributed to oxygen deficiency centers. The mechanism of two-photon ionization plays a critical role at sub-damage site. Compared to the Raman spectra of pristine site, intensity of Raman spectra is very high at a lower energy density, while it decreased at a higher energy density.

  1. CALCULATION OF MAGNETIC-X-RAY DICHROISM IN 4D AND 5D ABSORPTION-SPECTRA OF ACTINIDES

    NARCIS (Netherlands)

    OGASAWARA, H; KOTANI, A; THOLE, BT

    1991-01-01

    We present atomic calculations of the magnetic dichroism in 4d and 5d x-ray-absorption (XAS) spectra of trivalent actinide ions. The calculations are carried out for both linearly and circularly polarized light at zero temperature. Large magnetic dichroism is predicted for 5d XAS with

  2. Hierarchy of stochastic Schrödinger equation towards the calculation of absorption and circular dichroism spectra

    Science.gov (United States)

    Ke, Yaling; Zhao, Yi

    2017-05-01

    A theoretically solid and numerically exact method is presented for the calculation of absorption and circular dichroism (CD) spectra of molecular aggregates immersed in a harmonic bath constituted as the combination of some prominent quantized vibrational modes and continuous overdamped Brownian oscillators. The feasibility and the validity of newly proposed method are affirmed in the analytical monomer spectra. To go beyond the independent local bath approximation, all the correlations of site energy fluctuations and excitonic coupling fluctuations are included in our strategy, and their influence on the absorption and CD spectra is investigated based on the Frenkel exciton model of homodimer. In the end, a good fit of the absorption and part of CD spectra for the entire B800-B850 ring in the light-harvesting complexes 2 of purple bacteria to the experimental data is given, and the simulation results suggest that the asymmetry in the 800 nm region of CD spectra is actually an indication of B800-B850 inter-ring coupling.

  3. 8200 to 11200 A spectra of peculiar emission-line objects with infrared excess

    International Nuclear Information System (INIS)

    Andrillat, Y.; Swings, J.P.

    1976-01-01

    Spectra of 25 peculiar emission-line stars with infrared excesses were obtained in the 8200--11200 A region, using a grating spectrograph equipped with an S-1 photocathode image-tube at the Cassegrain focus of the 1.93 m (77 inch) telescope at the Haute Provence Observatory. The strongest emission features shown on the figure are due essentially to lines of the Paschen series, of the Ca II triplet, and of He I lambda 10830, O I lambda 8446, [S III] lambda lambda 9069 and 9532, and [Fe III] lambda 10504; a strong emission present at 9999 A on most of the spectra remains unidentified

  4. Theoretically predicted soft x-ray emission and absorption spectra of graphitic-structured BC2N

    Science.gov (United States)

    Muramatsu, Yasuji

    Theoretical B K, C K and N K x-ray emission/absorption spectra of three possible graphitic-structured BC2N clusters are predicted based on the B2p-, C2p-, and N2p- density-of-states (DOS) calculated by discrete variational (DV)-X[alpha] molecular orbital calculations. Several prominent differences in DOS spectral features among BC2Ns, h-BN, and graphite are confirmed from comparison of calculated B2p-, C2p-, and N2p-DOS spectra. These variations in the spectra allow BC2N structures to be positively identified by high-resolution x-ray emission/absorption spectroscopy in the B K, C K, and N K regions.

  5. Simulation of X-ray absorption spectra with orthogonality constrained density functional theory.

    Science.gov (United States)

    Derricotte, Wallace D; Evangelista, Francesco A

    2015-06-14

    Orthogonality constrained density functional theory (OCDFT) [F. A. Evangelista, P. Shushkov and J. C. Tully, J. Phys. Chem. A, 2013, 117, 7378] is a variational time-independent approach for the computation of electronic excited states. In this work we extend OCDFT to compute core-excited states and generalize the original formalism to determine multiple excited states. Benchmark computations on a set of 13 small molecules and 40 excited states show that unshifted OCDFT/B3LYP excitation energies have a mean absolute error of 1.0 eV. Contrary to time-dependent DFT, OCDFT excitation energies for first- and second-row elements are computed with near-uniform accuracy. OCDFT core excitation energies are insensitive to the choice of the functional and the amount of Hartree-Fock exchange. We show that OCDFT is a powerful tool for the assignment of X-ray absorption spectra of large molecules by simulating the gas-phase near-edge spectrum of adenine and thymine.

  6. Simulation of the absorption spectra of nanometallic Al particles with core-shell structure: size-dependent interband transitions

    Energy Technology Data Exchange (ETDEWEB)

    Peng Yajing; Wang Yinghui; Yang Yanqiang, E-mail: yqyang@hit.edu.c [Harbin Institute of Technology, Center for Condensed Matter Science and Technology, Department of Physics (China); Dlott, Dana D., E-mail: dlott@illinois.ed [University of Illinois at Urbana-Champaign, School of Chemical Sciences (United States)

    2010-03-15

    Nanoaluminum combined with an oxidizing polymer binder is representative of a new class of nanotechnology energetic materials termed 'structural energetic materials' that can be laser initiated by near-infrared heating of the Al particles. The visible and near-IR absorption spectra of Al nanoparticles passivated by the native oxide Al{sub 2}O{sub 3}, embedded in nitrocellulose (NC) binder, are simulated numerically using a model for the metallic dielectric function that incorporates the effects of interband transitions. The effects of oxide thickness, nanoparticle size and size distribution, and particle shape on the absorption characteristics are investigated. The nanoparticle spectra evidence an absorption peak and valley in the 550-1,100 nm range that redshift with decreasing nanoparticle size. Calculations indicate that this peak-valley structure results from interband transitions, and the unusual redshift cannot be explained without using an interband transition onset frequency that varies with nanoparticle size.

  7. Simulation of the absorption spectra of nanometallic Al particles with core-shell structure: size-dependent interband transitions

    Science.gov (United States)

    Peng, Yajing; Wang, Yinghui; Yang, Yanqiang; Dlott, Dana D.

    2010-03-01

    Nanoaluminum combined with an oxidizing polymer binder is representative of a new class of nanotechnology energetic materials termed "structural energetic materials" that can be laser initiated by near-infrared heating of the Al particles. The visible and near-IR absorption spectra of Al nanoparticles passivated by the native oxide Al2O3, embedded in nitrocellulose (NC) binder, are simulated numerically using a model for the metallic dielectric function that incorporates the effects of interband transitions. The effects of oxide thickness, nanoparticle size and size distribution, and particle shape on the absorption characteristics are investigated. The nanoparticle spectra evidence an absorption peak and valley in the 550-1,100 nm range that redshift with decreasing nanoparticle size. Calculations indicate that this peak-valley structure results from interband transitions, and the unusual redshift cannot be explained without using an interband transition onset frequency that varies with nanoparticle size.

  8. Optical-absorption spectra associated with shallow donor impurities in GaAs-(Ga,Al)As quantum-dots

    International Nuclear Information System (INIS)

    Silva Valencia, J.

    1995-08-01

    The binding energy of a hydrogenic donor impurity and the optical-absorption spectra associated with transitions between the n=1 valence level and the donor-impurity band were calculated for infinite barrier-well spherical GaAs-(Ga,Al)As quantum-dots of different radii, using the effective mass approximation within a variational scheme. An absorption peak associated with transitions involving impurities at the center of the well and a peak related with impurities at the edge of the dot were the main features observed for the different radii of the dots considered in the calculations. Also as a result of the higher electronic confinement in a quantum- dot, we found a much wider energy range of the absorption spectra when compared to infinite GaAs-(Ga,Al)As quantum-wells and quantum-well wires of width and diameter comparable to the diameter of the quantum dot. (author). 13 refs, 3 figs

  9. Effects of excited state mixing on transient absorption spectra in dimers Application to photosynthetic light-harvesting complex II

    CERN Document Server

    Valkunas, L; Trinkunas, G; Müller, M G; Holzwarth, A R

    1999-01-01

    The excited state mixing effect is taken into account considering the difference spectra of dimers. Both the degenerate (homo) dimer as well as the nondegenerate (hetero) dimer are considered. Due to the higher excited state mixing with the two-exciton states in the homodimer, the excited state absorption (or the difference spectrum) can be strongly affected in comparison with the results obtained in the Heitler-London approximation. The difference spectrum of the heterodimer is influenced by two resonance effects (i) mixing of the ground state optical transitions of both monomers in the dimer and (ii) mixing of the excited state absorption of the excited monomer with the ground state optical transition in the nonexcited monomer. These effects have been tested by simulating the difference absorption spectra of the light-harvesting complex of photosystem II (LHC II) experimentally obtained with the 60 fs excitation pulses at zero delay times and various excitation wavelengths. The pairs of coupled chlorophylls...

  10. Discovery of carbon radio recombination lines in absorption towards Cygnus A

    NARCIS (Netherlands)

    Oonk, J.B.R.; et al., [Unknown; Alexov, A.; Hessels, J.W.T.; van der Horst, A.; van Leeuwen, J.; Markoff, S.; Miller-Jones, J.C.A.; Swinbank, J.; Wijers, R.A.M.J.

    2014-01-01

    We present the first detection of carbon radio recombination line absorption along the line of sight to Cygnus A. The observations were carried out with the Low Frequency Array in the 33-57 MHz range. These low-frequency radio observations provide us with a new line of sight to study the diffuse,

  11. Discovery of carbon radio recombination lines in absorption towards Cygnus A

    NARCIS (Netherlands)

    Oonk, J. B. R.; van Weeren, R. J.; Salgado, F.; Morabito, L. K.; Tielens, A. G. G. M.; Rottgering, H. J. A.; Asgekar, A.; White, G. J.; Alexov, A.; Anderson, J.; Avruch, I. M.; Batejat, F.; Beck, R.; Bell, M. E.; van Bemmel, I.; Bentum, M. J.; Bernardi, G.; Best, P.; Bonafede, A.; Breitling, F.; Brentjens, M.; Broderick, J.; Brüggen, M.; Butcher, H. R.; Ciardi, B.; Conway, J. E.; Corstanje, A.; de Gasperin, F.; de Geus, E.; de Vos, M.; Duscha, S.; Eislöffel, J.; Engels, D.; van Enst, J.; Falcke, H.; Fallows, R. A.; Fender, R.; Ferrari, C.; Frieswijk, W.; Garrett, M. A.; Grießmeier, J.; Hamaker, J. P.; Hassall, T. E.; Heald, G.; Hessels, J. W. T.; Hoeft, M.; Horneffer, A.; van der Horst, A.; Iacobelli, M.; Jackson, N. J.; Juette, E.; Karastergiou, A.; Klijn, W.; Kohler, J.; Kondratiev, V. I.; Kramer, M.; Kuniyoshi, M.; Kuper, G.; van Leeuwen, J.; Maat, P.; Macario, G.; Mann, G.; Markoff, S.; McKean, J. P.; Mevius, M.; Miller-Jones, J. C. A.; Mol, J. D.; Mulcahy, D. D.; Munk, H.; Norden, M. J.; Orru, E.; Paas, H.; Pandey-Pommier, M.; Pandey, V. N.; Pizzo, R.; Polatidis, A. G.; Reich, W.; Scaife, A. M. M.; Schoenmakers, A.; Schwarz, D.; Shulevski, A.; Sluman, J.; Smirnov, O.; Sobey, C.; Stappers, B. W.; Steinmetz, M.; Swinbank, J.; Tagger, M.; Tang, Y.; Tasse, C.; Veen, S. ter; Thoudam, S.; Toribio, C.; van Nieuwpoort, R.; Vermeulen, R.; Vocks, C.; Vogt, C.; Wijers, R. A. M. J.; Wise, M. W.; Wucknitz, O.; Yatawatta, S.; Zarka, P.; Zensus, A.

    We present the first detection of carbon radio recombination line absorption along the line of sight to Cygnus A. The observations were carried out with the Low Frequency Array in the 33-57 MHz range. These low-frequency radio observations provide us with a new line of sight to study the diffuse,

  12. A SEMI-ANALYTICAL LINE TRANSFER MODEL TO INTERPRET THE SPECTRA OF GALAXY OUTFLOWS

    International Nuclear Information System (INIS)

    Scarlata, C.; Panagia, N.

    2015-01-01

    We present a semi-analytical line transfer model, (SALT), to study the absorption and re-emission line profiles from expanding galactic envelopes. The envelopes are described as a superposition of shells with density and velocity varying with the distance from the center. We adopt the Sobolev approximation to describe the interaction between the photons escaping from each shell and the remainder of the envelope. We include the effect of multiple scatterings within each shell, properly accounting for the atomic structure of the scattering ions. We also account for the effect of a finite circular aperture on actual observations. For equal geometries and density distributions, our models reproduce the main features of the profiles generated with more complicated transfer codes. Also, our SALT line profiles nicely reproduce the typical asymmetric resonant absorption line profiles observed in starforming/starburst galaxies whereas these absorption profiles cannot be reproduced with thin shells moving at a fixed outflow velocity. We show that scattered resonant emission fills in the resonant absorption profiles, with a strength that is different for each transition. Observationally, the effect of resonant filling depends on both the outflow geometry and the size of the outflow relative to the spectroscopic aperture. Neglecting these effects will lead to incorrect values of gas covering fraction and column density. When a fluorescent channel is available, the resonant profiles alone cannot be used to infer the presence of scattered re-emission. Conversely, the presence of emission lines of fluorescent transitions reveals that emission filling cannot be neglected

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

    Energy Technology Data Exchange (ETDEWEB)

    Sellberg, Jonas A.; Nilsson, Anders [Department of Physics, AlbaNova University Center, Stockholm University, S-106 91 Stockholm (Sweden); SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Kaya, Sarp [SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Segtnan, Vegard H. [SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Nofima AS, N-1430 Ås (Norway); Chen, Chen [SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Department of Chemistry, Stanford University, Stanford, California 94305 (United States); Tyliszczak, Tolek [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Ogasawara, Hirohito; Nordlund, Dennis [Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, P.O. Box 20450, Stanford, California 94309 (United States); Pettersson, Lars G. M. [Department of Physics, AlbaNova University Center, Stockholm University, S-106 91 Stockholm (Sweden)

    2014-07-21

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

  14. How to remove the influence of trace water from the absorption spectra of SWNTs dispersed in ionic liquids

    Science.gov (United States)

    Zhang, Daqi

    2011-01-01

    Summary Single-walled carbon nanotubes (SWNTs) can be efficiently dispersed in the imidazolium-based ionic liquids (ILs), at relatively high concentration, with their intrinsic structure and properties retained. Due to the hygroscopicity of the ILs, water bands may be introduced in the absorption spectra of IL-dispersed SWNTs and cause problems in spectral deconvolution and further analysis. In order to remove this influence, a quantitative characterization of the trace water in [BMIM]+[PF6]− and [BMIM]+[BF4]− was carried out by means of UV–vis-NIR absorption spectroscopy. A simple yet effective method involving spectral subtraction of the water bands was utilized, and almost no difference was found between the spectra of the dry IL-dispersed SWNT samples treated under vacuum for 10 hours and the spectra of the untreated samples with subtraction of the pure water spectrum. This result makes it more convenient to characterize SWNTs with absorption spectra in the IL-dispersion system, even in the presence of trace amount of water. PMID:22003471

  15. Electronic Absorption Spectra of Tetrapyrrole-Based Pigments via TD-DFT: A Reduced Orbital Space Study.

    Science.gov (United States)

    Shrestha, Kushal; Virgil, Kyle A; Jakubikova, Elena

    2016-07-28

    Tetrapyrrole-based pigments play a crucial role in photosynthesis as principal light absorbers in light-harvesting chemical systems. As such, accurate theoretical descriptions of the electronic absorption spectra of these pigments will aid in the proper description and understanding of the overall photophysics of photosynthesis. In this work, time-dependent density functional theory (TD-DFT) at the CAM-B3LYP/6-31G* level of theory is employed to produce the theoretical absorption spectra of several tetrapyrrole-based pigments. However, the application of TD-DFT to large systems with several hundreds of atoms can become computationally prohibitive. Therefore, in this study, TD-DFT calculations with reduced orbital spaces (ROSs) that exclude portions of occupied and virtual orbitals are pursued as a viable, computationally cost-effective alternative to conventional TD-DFT calculations. The effects of reducing orbital space size on theoretical spectra are qualitatively and quantitatively described, and both conventional and ROS results are benchmarked against experimental absorption spectra of various tetrapyrrole-based pigments. The orbital reduction approach is also applied to a large natural pigment assembly that comprises the principal light-absorbing component of the reaction center in purple bacteria. Overall, we find that TD-DFT calculations with proper and judicious orbital space reductions can adequately reproduce conventional, full orbital space, TD-DFT results of all pigments studied in this work.

  16. Electronic absorption spectra of rare earth (III) species in NaCl-2CsCl eutectic based melts

    Science.gov (United States)

    Volkovich, V. A.; Ivanov, A. B.; Yakimov, S. M.; Tsarevskii, D. V.; Golovanova, O. A.; Sukhikh, V. V.; Griffiths, T. R.

    2016-09-01

    Electronic absorption spectra of ions of trivalent rare earth elements were measured in the melts based on NaCl-2CsCl eutectic in the wavelength ranges of 190-1350 and 1450-1700 nm. The measurements were performed at 550-850 °C. The EAS of Y, La, Ce and Lu containing melts have no absorption bands in the studied regions. For the remaining REEs (Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb) the absorption bands in the EAS were assigned to the corresponding f-f electron transitions. The Stark effect was observed for Yb(III) F5/2 excited state. Increasing temperature leads to decreasing intensity of the absorption bands, except for the bands resulting from hypersensitive transitions. Beer's law was confirmed up to 0.4 M solutions of REE.

  17. Study of electron transition energies between anions and cations in spinel ferrites using differential UV–vis absorption spectra

    Energy Technology Data Exchange (ETDEWEB)

    Xue, L.C.; Wu, L.Q. [Hebei Advanced Thin Film Laboratory, Department of Physics, Hebei Normal University, Shijiazhuang City 050024 (China); Li, S.Q. [Hebei Advanced Thin Film Laboratory, Department of Physics, Hebei Normal University, Shijiazhuang City 050024 (China); School of Sciences, Hebei University of Science and Technology, Shijiazhuang City 050018 (China); Li, Z.Z. [Hebei Advanced Thin Film Laboratory, Department of Physics, Hebei Normal University, Shijiazhuang City 050024 (China); Tang, G.D., E-mail: tanggd@mail.hebtu.edu.cn [Hebei Advanced Thin Film Laboratory, Department of Physics, Hebei Normal University, Shijiazhuang City 050024 (China); Qi, W.H.; Ge, X.S.; Ding, L.L. [Hebei Advanced Thin Film Laboratory, Department of Physics, Hebei Normal University, Shijiazhuang City 050024 (China)

    2016-07-01

    It is very important to determine electron transition energies (E{sub tr}) between anions and different cations in order to understand the electrical transport and magnetic properties of a material. Many authors have analyzed UV–vis absorption spectra using the curve (αhν){sup 2} vs E, where α is the absorption coefficient and E(=hν) is the photon energy. Such an approach can give only two band gap energies for spinel ferrites. In this paper, using differential UV–vis absorption spectra, dα/dE vs E, we have obtained electron transition energies (E{sub tr}) between the anions and cations, Fe{sup 2+} and Fe{sup 3+} at the (A) and [B] sites and Ni{sup 2+} at the [B] sites for the (A)[B]{sub 2}O{sub 4} spinel ferrite samples Co{sub x}Ni{sub 0.7−x}Fe{sub 2.3}O{sub 4} (0.0≤x≤0.3), Cr{sub x}Ni{sub 0.7}Fe{sub 2.3−x}O{sub 4} (0.0≤x≤0.3) and Fe{sub 3}O{sub 4}. We suggest that the differential UV–vis absorption spectra should be accepted as a general analysis method for determining electron transition energies between anions and cations.

  18. Calculation of emission and absorption spectra of LTE plasma by the STA [Super Transition Array] method

    International Nuclear Information System (INIS)

    Bar-Shalon, A.; Oreg, J.

    1991-01-01

    Recent improvements in the Super Transition Array (STA) method for calculating Bound-Bound (BB) and Bound-Free (BF) emission and absorption spectra for LTE plasma are described and illustrated. The method accounts for all possible BB and BF radiative transitions in the plasma. Full detailed first order quantum relativistic treatment is used for calculating transition energies and probabilities. The enormous number of configurations are divided into sets of superconfigurations comprised of a collection of energetically grouped configurations. The contribution of the transition array between two superconfigurations to a specific one-electron transition is then represented by a Gaussian whose moments are calculated accurately using a technique that bypasses the necessity of direct summation over all the levels involved. The calculation of these moments involves the populations of the configurations given by their statistical weights and the Boltzmann factor. For each configuration within the super configuration we use zeroeth order energies in the Boltzmann factor corrected by a super configuration averaged first order term. The structure of the spectrum is increasingly revealed by splitting each STA into a number of smaller STAs. When the spectrum converges it describes the detailed 'UTA' structure, where each configuration-to-configuration array is represented by a separate Gaussian with first order energy in the Boltzmann factor. Convergence is reached with only a few thousand STAs, at most, which makes the calculations practical. It should be pointed out that in this treatment the STA moments are obtained by summing over all level-to-level transitions, rather than configuration-to-configuration average transitions. 4 refs., 9 figs

  19. Calculation of emission and absorption spectra of LTE plasma by the STA method

    International Nuclear Information System (INIS)

    Oreg, A.B.J.; Goldstein, W.H.

    1991-01-01

    Recent improvements in the Super Transition Array (STA) method for calculating Bound-Bound (BB) and Bound-Free (BF) emission and absorption spectra for LTE plasma are described and illustrated. The method accounts for all possible BB and BF radiative transitions in the plasma. Full detailed first order quantum relativistic treatment is used for calculating transition energies and probabilities. The enormous number of configurations are divided into sets of superconfigurations comprised of a collection of energetically grouped configurations to a specific one-electron transition is then represented by a Gaussian whose moments (total intensity, average energy and variance) are calculated accurately using a technique that bypasses the necessity of direct summation over all the levels involved. The calculation of these moments involves the populations of the configurations given by their statistical weights and the Boltzmann factor. For each configuration within the superconfiguration the authors use zeroeth order energies in the Boltzmann factor corrected by a superconfiguration averaged first order term. The structure of the spectrum is increasingly revealed by splitting each STA into a number of smaller STAs. When the spectrum converges it describes the detailed UTA structure, where each configuration-to-configuration array is represented by a separate Gaussian with first order energy in the Boltzmann factor. Convergence is reached with only a few thousand STAs, at most, which makes the calculations practical. It should be pointed out that in this treatment the STA moments are obtained by summing over all level-to-level transitions, rather than configuration-to-configuration average transitions. The authors also take into account orbital relaxation by calculating orbitals and energies for each superconfiguration in its own, optimized potential

  20. Calculation of emission and absorption spectra of LTE plasma by the STA (Super Transition Array) method

    Science.gov (United States)

    Bar-Shalon, A.; Oreg, J.; Goldstein, W. H.

    1991-01-01

    Recent improvements in the Super Transition Array (STA) method for calculating Bound-Bound (BB) and Bound-Free (BF) emission and absorption spectra for Laser Thermal Equilibrium (LTE) plasma are described and illustrated. The method accounts for all possible BB and BF radiative transitions in the plasma. Full detailed first order quantum relativistic treatment is used for calculating transition energies and probabilities. The enormous number of configurations are divided into sets of superconfigurations comprised of a collection of energetically grouped configurations. The contribution of the transition array between two superconfigurations to a specific one-electron transition is then represented by a Gaussian whose moments are calculated accurately using a technique that bypasses the necessity of direct summation over all the levels involved. The calculation of these moments involves the populations of the configurations given by their statistical weights and the Boltzmann factor. For each configuration within the super configuration zeroeth order energies are used in the Boltzmann factor corrected by a super configuration averaged first order term. The structure of the spectrum is increasingly revealed by splitting each STA into a number of smaller STAs. When the spectrum converges it describes the detailed UTA structure, where each configuration-to-configuration array is represented by a separate Gaussian with first order energy in the Boltzmann factor. Convergence is reached with only a few thousand STAs, at most, which makes the calculations practical. It should be pointed out that in this treatment the STA moments are obtained by summing over all level-to-level transitions, rather than configuration-to-configuration average transitions.

  1. Compact characterization of liquid absorption and emission spectra using linear variable filters integrated with a CMOS imaging camera.

    Science.gov (United States)

    Wan, Yuhang; Carlson, John A; Kesler, Benjamin A; Peng, Wang; Su, Patrick; Al-Mulla, Saoud A; Lim, Sung Jun; Smith, Andrew M; Dallesasse, John M; Cunningham, Brian T

    2016-07-08

    A compact analysis platform for detecting liquid absorption and emission spectra using a set of optical linear variable filters atop a CMOS image sensor is presented. The working spectral range of the analysis platform can be extended without a reduction in spectral resolution by utilizing multiple linear variable filters with different wavelength ranges on the same CMOS sensor. With optical setup reconfiguration, its capability to measure both absorption and fluorescence emission is demonstrated. Quantitative detection of fluorescence emission down to 0.28 nM for quantum dot dispersions and 32 ng/mL for near-infrared dyes has been demonstrated on a single platform over a wide spectral range, as well as an absorption-based water quality test, showing the versatility of the system across liquid solutions for different emission and absorption bands. Comparison with a commercially available portable spectrometer and an optical spectrum analyzer shows our system has an improved signal-to-noise ratio and acceptable spectral resolution for discrimination of emission spectra, and characterization of colored liquid's absorption characteristics generated by common biomolecular assays. This simple, compact, and versatile analysis platform demonstrates a path towards an integrated optical device that can be utilized for a wide variety of applications in point-of-use testing and point-of-care diagnostics.

  2. Origin of low-energy lines in electron spectra of pure beta emitters

    International Nuclear Information System (INIS)

    Spalek, A.; Dragoun, O.; Rysavy, M.; Brabec, V.; Dragounova, N.

    1998-01-01

    In the electron spectra of 241 Pu and 63 Ni, line structures were found at energies below 1 keV (in addition to the continuous spectrum), ie., two complex lines at roughly 260 and 500 eV. The interpretation of this effect is as follows: The surfaces of nearly all sources used in the electron spectrometry of radionuclides contain a thin contamination layer mainly consisting of carbon and oxygen atoms. When bombarding this layer, ionization of the K shell takes place in the C and O atoms. Filling this vacancy gives rise to the emission of Auger KLL electrons corresponding to carbon and oxygen with kinetic energies of about 261 and 511 eV. The lines can be broadened due to the chemical bonding of the C and O atoms. This effect was examined in the beta spectra of the above two nuclides. Monte Carlo calculations were performed for the transport of electrons through the spectrometric source material to estimate the intensity of the KLL lines corresponding to the excitation of the carbon atoms. Lines of this type can be expected in the electron spectra of nearly any current radioactive source

  3. Absorption spectra of trapped holes in anatase TiO2

    DEFF Research Database (Denmark)

    Zawadzki, Pawel

    2013-01-01

    absorption spectroscopy (TAS), but the understanding of the optical absorption due to trapped carriers in TiO2 is incomplete. On the basis of the generalized Δ self-consistent field density functional theory (Δ-SCF DFT) calculations, we attribute the experimentally observed absorption band at 430-550 nm...

  4. Time-dependent excitation and ionization modelling of absorption-line variability due to GRB080310

    DEFF Research Database (Denmark)

    Vreeswijk, P.M.; De Cia, A.; Jakobsson, P.

    2013-01-01

    We model the time-variable absorption of Feii, Feiii, Siii, Cii and Crii detected in Ultraviolet and Visual Echelle Spectrograph (UVES) spectra of gamma-ray burst (GRB) 080310, with the afterglow radiation exciting and ionizing the interstellar medium in the host galaxy at a redshift of z = 2.427...

  5. EMISSION LINES BETWEEN 1 AND 2 keV IN COMETARY X-RAY SPECTRA

    Energy Technology Data Exchange (ETDEWEB)

    Ewing, Ian; Christian, Damian J. [Department of Physics and Astronomy, California State University, 18111 Nordhoff Street, Northridge, CA 91330 (United States); Bodewits, Dennis [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Dennerl, Konrad [Max-Planck-Institut fuer extraterrestrische Physik, Postfach 1312, D-85741 Garching Germany (Germany); Lisse, Carey M. [Planetary Exploration Group, Space Department, Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Rd, Laurel, MD 20723 (United States); Wolk, Scott J., E-mail: ian.ewing.794@my.csun.edu, E-mail: daman.christian@csun.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2013-01-20

    We present the detection of new cometary X-ray emission lines in the 1.0-2.0 keV range using a sample of comets observed with the Chandra X-Ray Observatory and ACIS spectrometer. We have selected five comets from the Chandra sample with good signal-to-noise spectra. The surveyed comets are C/1999 S4 (LINEAR), C/1999 T1 (McNaught-Hartley), 153P/2002 (Ikeya-Zhang), 2P/2003 (Encke), and C/2008 8P (Tuttle). We modeled the spectra with an extended version of our solar wind charge exchange (SWCX) emission model. Above 1 keV, we find Ikeya-Zhang to have strong emission lines at 1340 and 1850 eV which we identify as being created by SWCX lines of Mg XI and Si XIII, respectively, and weaker emission lines at 1470, 1600, and 1950 eV formed by SWCX of Mg XII, Mg XI, and Si XIV, respectively. The Mg XI and XII and Si XIII and XIV lines are detected at a significant level for the other comets in our sample (LS4, MH, Encke, 8P), and these lines promise additional diagnostics to be included in SWCX models. The silicon lines in the 1700-2000 eV range are detected for all comets, but with the rising background and decreasing cometary emission, we caution that these detections need further confirmation with higher resolution instruments.

  6. Continuum and discrete pulsed cavity ring down laser absorption spectra of Br2 vapor.

    Science.gov (United States)

    Sharma, Ramesh C; Huang, Hong-Yi; Chuang, Wang-Ting; Lin, King-Chuen

    2005-07-01

    The absorption cross-sections at room temperature are reported for the first time, of Br2 vapor in overlapping bound-free and bound-bound transition of A(3)pi1u Br2. We obtained discrete absorption cross-section in the rotational structure, the continuum absorption cross-sections, and were also able to measure the absorption cross-section in separate contribution of A(3)pi1u Br2. The absorption cross-sections are increasing with increasing excitation energy in the wavelength region 510-535 nm.

  7. Optical absorption spectra of the uranium (4+) ion in the thorium germanate matrix

    CERN Document Server

    Gajek, Z; Antic-Fidancev, E

    1997-01-01

    Visible and infrared absorption measurements on the U sup 4 sup + ion in tetragonal zircon-type matrix beta-ThGeO sub 4 are reported and analysed in terms of the standard parametrization scheme. The observed 17 main peaks and a number of less intense lines have been assigned and fitted to most of the 32 allowed electric dipole transitions with the root mean square error equal to 65 cm sup - sup 1. The free-ion parameters obtained for the model Hamiltonian, zeta 5f = 1809 cm sup - sup 1 , F sup 2 =43 065 cm sup - sup 1 , F sup 4 =38 977 cm sup - sup 1 and F sup 6 =24 391 cm sup - sup 1 , as well as the corresponding crystal-field parameters, B sub 0 sup 2 =-1790 cm sup - sup 1 , B sub 0 sup 4 =1200 cm sup - sup 1 , B sub 4 sup 4 =3260 cm sup - sup 1 , B sub 0 sup 6 =-3170 cm sup - sup 1 and B sub 4 sup 6 =990 cm sup - sup 1 , agree fairly well with the initial theoretical estimations. The results are discussed in relation to the previous spectroscopic study on the scheelite-type matrix UGeO sub 4. (author)

  8. Vibrational absorption spectra from vibrational coupled cluster damped linear response functions calculated using an asymmetric Lanczos algorithm

    DEFF Research Database (Denmark)

    Thomsen, Bo; Hansen, Mikkel Bo; Seidler, Peter

    2012-01-01

    . The absorption spectrum can in this formulation be seen as a matrix function of the characteristic VCC Jacobian response matrix. The asymmetric matrix version of the Lanczos method is used to generate a tridiagonal representation of the VCC response Jacobian. Solving the complex response equations...... in the relevant Lanczos space provides a method for calculating the VCC damped response functions and thereby subsequently the absorption spectra. The convergence behaviour of the algorithm is discussed theoretically and tested for different levels of completeness of the VCC expansion. Comparison is made...... with results from the recently reported [P. Seidler, M. B. Hansen, W. Györffy, D. Toffoli, and O. Christiansen, J. Chem. Phys. 132, 164105 (2010)] vibrational configuration interaction damped response function calculated using a symmetric Lanczos algorithm. Calculations of IR spectra of oxazole, cyclopropene...

  9. Identification of MgII Absorption Line Systems from SDSS Quasar ...

    Indian Academy of Sciences (India)

    In the first step, the SDSS spectra are corrected for the Galactic extinction using the reddening map of Schlegel et al. (1998) and then shifted to its rest wave- length. In order to measure line parameters reliably, we choose those wavelength ranges as pseudo-continua, which are not affected by prominent emission lines.

  10. Polarized absorption spectra of aromatic radicals in stretched polymer film. 3. Radical ions of acridine and phenazine

    Energy Technology Data Exchange (ETDEWEB)

    Sekigucki, K.; Hiratsuka, H.; Tanizaki, Y.; Hatano, Y.

    1980-02-21

    Radical anions and cations of acridine and phenazine have been prepared in polymer film by ..gamma..-ray irradiation at 77 K. For the preparation of radical anions the sample was incorporated into polyethylene film by sec-butylamine, while for radical cations poly(vinyl chloride) film and sec-butyl chloride were used. Polarized absorption spectra of these radical ions have been measured in stretched polymer film and analyzed qualitatively in terms of molecular orbital calculations.

  11. Calculation of Vibrational and Electronic Excited-State Absorption Spectra of Arsenic-Water Complexes Using Density Functional Theory

    Science.gov (United States)

    2016-06-03

    of Arsenic-Water Complexes Using Density Functional Theory June 3, 2016 Approved for public release; distribution is unlimited. L. Huang S.g... Density Functional Theory L. Huang, S.G. Lambrakos, A. Shabaev,1 and L. Massa2 Naval Research Laboratory, Code 6394 4555 Overlook Avenue, SW...absorption spectra for As-H2O complexes using density functional theory (DFT) and time-dependent density functional theory (TD-DFT). DFT and TD-DFT can

  12. Time-resolved spectra of excited-state absorption in Er3+ doped YAlO3

    NARCIS (Netherlands)

    Pollnau, Markus; Heumann, E.; Huber, G.

    1992-01-01

    A pump- and probe-beam technique is used for measuring time-resolved excited-state absorption (ESA) and stimulated-emission (SE) spectra of Er3+ doped YAlO3. The Er3+ 4I15/2 -> 4F7/2 transition of the sample is excited at 488 nm by an excimer laser pumped dye laser. The ESA and SE of broadband xenon

  13. Förster resonance energy transfer, absorption and emission spectra in multichromophoric systems. III. Exact stochastic path integral evaluation.

    Science.gov (United States)

    Moix, Jeremy M; Ma, Jian; Cao, Jianshu

    2015-03-07

    A numerically exact path integral treatment of the absorption and emission spectra of open quantum systems is presented that requires only the straightforward solution of a stochastic differential equation. The approach converges rapidly enabling the calculation of spectra of large excitonic systems across the complete range of system parameters and for arbitrary bath spectral densities. With the numerically exact absorption and emission operators, one can also immediately compute energy transfer rates using the multi-chromophoric Förster resonant energy transfer formalism. Benchmark calculations on the emission spectra of two level systems are presented demonstrating the efficacy of the stochastic approach. This is followed by calculations of the energy transfer rates between two weakly coupled dimer systems as a function of temperature and system-bath coupling strength. It is shown that the recently developed hybrid cumulant expansion (see Paper II) is the only perturbative method capable of generating uniformly reliable energy transfer rates and emission spectra across a broad range of system parameters.

  14. Research program in nuclear and solid state physics. [including pion absorption spectra and muon spin precession

    Science.gov (United States)

    1974-01-01

    The survey of negative pion absorption reactions on light and medium nuclei was continued. Muon spin precession was studied using an iron target. An impulse approximation model of the pion absorption process implied that the ion will absorb almost exclusively on nucleon pairs, single nucleon absorption being suppressed by energy and momentum conservation requirements. For measurements on both paramagnetic and ferromagnetic iron, the external magnetic field was supplied by a large C-type electromagnet carrying a current of about 100 amperes.

  15. Development of uniform hazard response spectra for rock sites considering line and point sources of earthquakes

    International Nuclear Information System (INIS)

    Ghosh, A.K.; Kushwaha, H.S.

    2001-12-01

    Traditionally, the seismic design basis ground motion has been specified by normalised response spectral shapes and peak ground acceleration (PGA). The mean recurrence interval (MRI) used to computed for PGA only. It is shown that the MRI associated with such response spectra are not the same at all frequencies. The present work develops uniform hazard response spectra i.e. spectra having the same MRI at all frequencies for line and point sources of earthquakes by using a large number of strong motion accelerograms recorded on rock sites. Sensitivity of the number of the results to the changes in various parameters has also been presented. This work is an extension of an earlier work for aerial sources of earthquakes. These results will help to determine the seismic hazard at a given site and the associated uncertainities. (author)

  16. Absorption and fluorescence spectra of the neutral and anionic green fluorescent protein chromophore: Franck-Condon simulation

    Science.gov (United States)

    Huang, Tsung-wei; Yang, Ling; Zhu, Chaoyuan; Lin, Sheng Hsien

    2012-07-01

    Absorption and fluorescence spectra of the neutral and anionic green fluorescent protein (GFP) chromophore, namely p-hydroxybenzylideneimidazolidinone (p-HBDI), have been simulated using the Franck-Condon factors including inhomogeneous broadening of solvent effect. Ground and the first excited states were calculated by time dependent density functional theory with and without the polarizable continuum model environment. Simulated peak of the neutral/anionic p-HBDI at 380 nm (423 nm)/421 nm agrees with experiment value 370 nm (434 nm)/419 nm for absorption (fluorescence) spectrum. Simulated width of the neutral/anionic p-HBDI at 0.51 eV (0.54 eV)/0.57 eV agrees with experiment value 0.54 eV (0.66 eV)/0.56 eV for absorption (fluorescence) spectrum.

  17. Optical Absorption of Impurities and Defects in Semiconducting Crystals Electronic Absorption of Deep Centres and Vibrational Spectra

    CERN Document Server

    Pajot, Bernard

    2013-01-01

    This book outlines, with the help of several specific examples, the important role played by absorption spectroscopy in the investigation of deep-level centers introduced in semiconductors and insulators like diamond, silicon, germanium and gallium arsenide by high-energy irradiation, residual impurities, and defects produced during crystal growth. It also describes the crucial role played by vibrational spectroscopy to determine the atomic structure and symmetry of complexes associated with light impurities like hydrogen, carbon, nitrogen and oxygen, and as a tool for quantitative analysis of these elements in the materials.

  18. Average extinction curves and relative abundances for quasi-stellar object absorption-line systems at 1 <=zabs < 2

    Science.gov (United States)

    York, Donald G.; Khare, Pushpa; Vanden Berk, Daniel; Kulkarni, Varsha P.; Crotts, Arlin P. S.; Lauroesch, James T.; Richards, Gordon T.; Schneider, Donald P.; Welty, Daniel E.; Alsayyad, Yusra; Kumar, Abhishek; Lundgren, Britt; Shanidze, Natela; Smith, Tristan; Vanlandingham, Johnny; Baugher, Britt; Hall, Patrick B.; Jenkins, Edward B.; Menard, Brice; Rao, Sandhya; Tumlinson, Jason; Turnshek, David; Yip, Ching-Wa; Brinkmann, Jon

    2006-04-01

    We have studied a sample of 809 MgII absorption systems with 1.0 <=zabs<= 1.86 in the spectra of Sloan Digital Sky Survey quasi-stellar objects (QSOs), with the aim of understanding the nature and abundance of the dust and the chemical abundances in the intervening absorbers. Normalized, composite spectra were derived, for abundance measurements, for the full sample and several subsamples, chosen on the basis of the line strengths and other absorber and QSO properties. Average extinction curves were obtained for the subsamples by comparing their geometric mean spectra with those of matching samples of QSOs without absorbers in their spectra. There is clear evidence for the presence of dust in the intervening absorbers. The 2175-Å feature is not present in the extinction curves, for any of the subsamples. The extinction curves are similar to the Small Magellanic Cloud (SMC) extinction curve with a rising ultraviolet (UV) extinction below 2200 Å. The absorber rest-frame colour excess, E(B-V), derived from the extinction curves, depends on the absorber properties and ranges from <0.001 to 0.085 for various subsamples. The column densities of MgII, AlII, SiII, CaII, TiII, CrII, MnII, FeII, CoII, NiII and ZnII do not show such a correspondingly large variation. The overall depletions in the high E(B-V) samples are consistent with those found for individual damped Lyman α systems, the depletion pattern being similar to halo clouds in the Galaxy. Assuming an SMC gas-to-dust ratio, we find a trend of increasing abundance with decreasing extinction; systems with NHI~ 1020cm-2 show solar abundance of Zn. The large velocity spread of strong MgII systems seems to be mimicked by weak lines of other elements. The ionization of the absorbers, in general appears to be low: the ratio of the column densities of AlIII to AlII is always less than 1/2. QSOs with absorbers are, in general, at least three times as likely to have highly reddened spectra as compared to QSOs without any

  19. The IR Spectra, Molar Absorptivity, and Integrated Molar Absorptivity of the C76-D2 and C84-D2:22 Isomers

    Directory of Open Access Journals (Sweden)

    T. Jovanovic

    2017-01-01

    Full Text Available The FT-IR spectra of the stable C76 and C84 isomers of D2 symmetry, isolated by the new, advanced extraction and chromatographic methods and processes, were recorded by the KBr technique, over the relevant region from 400 to 2000 cm−1, at room temperature. All the observed infrared bands are in excellent agreement with the semiempirical QCFF/PI, DFT, and TB potential calculations for these fullerenes, which is presented in this article, as the evidence of their validity. The molar absorptivity ε and the integrated molar absorptivity ψ of their IR absorption bands were determined and reported together with the relative intensities. Excellent agreement is found between the relative intensities of the main and characteristic absorption maxima calculated from ελ and from the ψλ values in adequate integration ranges. These results are significant for the identification and quantitative determination of the C76-D2 and C84-D2:22 fullerenes, either in natural resources on Earth and in space or in artificially synthesized biomaterials, electronic, optical, and biomedical devices, sensors, polymers, optical limiters, solar cells, organic field effect transistors, special lenses, diagnostic and therapeutic agents, pharmaceutical substances in biomedical engineering, and so forth.

  20. a High Resolution Spectroscopic Study of Absorption Line Profiles in the A-Band of Molecular Oxygen

    Science.gov (United States)

    Ritter, Kenneth James

    A study has been made of absorption line profiles in the A-band of molecular oxygen at 13120 cm('-1). High resolution spectra were obtained using a narrow linewidth tunable dye laser in conjunction with a multi-pass optical absorption cell, a photo-acoustic cell, and a variable temperature photo-acoustic cell. Line parameters were determined using a least-squares fitting routine which numerically adjusted parameters of certain standard line profile functions to obtain the best fit with the observed profiles. The standard line profiles used were the Voigt function, two Dicke-narrowed profiles, and a speed dependent Voigt profile. Clear deviations are shown between the observed and simple Voigt profiles, while the other three profiles were found to fit the observed profiles well. Line strengths, pressure broadening coefficients, and pressure induced frequency shifts were also determined from the measured profiles. Line strengths obtained from the absorption measurements are compared with expressions given by Childs and Mecke (1931), Schlapp (1932;1937), Tilford et al. (1965) and Watson (1968). The expressions of Tilford et al. (1965) and Watson (1968) are shown to be in closest agreement with the measurements. Self-broadening coefficients are compared with previous measurements made by other investigators as well as with theoretical calculations made using the semi-classical method of Smith and Giraud (1979). Pressure induced frequency shifts were determined by taking simultaneous spectra of two cells at different pressures. The pressure induced frequency shifts and broadening coefficients were measured in pure oxygen as a function of temperature ( -20(DEGREES)C to 100(DEGREES)C), as well as in air and the broadeners He, Ne, Ar, Kr, and Xe at ambient temperature. The measured gas broadening coefficients are shown to be in close agreement with values calculated using the method of Smith and Giraud (1979). It is also shown that the general behavior observed for the

  1. Uncertainty of Integrated Intensity Following Line Profile Fitting of Multiline Spectra.

    Science.gov (United States)

    Surmick, David M; Boukari, Hacene; Woodward, Jonathan; Stowe, Ashley C; Melikechi, Noureddine

    2018-01-01

    A novel method of determining the total uncertainty in the integrated intensity of fitted emission lines in multipeaked emission spectra is presented. The proposed method does not require an assumption of the type of line profile to be specified. The absolute difference between a fit and measured spectrum defines the uncertainty of the integrated signal intensity and is subsequently decomposed to determine the uncertainty of each peak in multiline fits. Decomposition relies on tabulating a weighting factor, which describes how each peak contributes to the total integral uncertainty. Applications of this method to quantitative approaches in laser-induced breakdown spectroscopy analysis are described.

  2. ABSORPTION-SPECTRA OF HUMAN FETAL AND ADULT OXYHEMOGLOBIN, DE-OXYHEMOGLOBIN, CARBOXYHEMOGLOBIN, AND METHEMOGLOBIN

    NARCIS (Netherlands)

    ZIJLSTRA, WG; MEEUWSENVANDERROEST, WP

    We determined the millimolar absorptivities of the four clinically relevant derivatives of fetal and adult human hemoglobin in the visible and near-infrared spectral range (450-1000 nm). As expected, spectral absorption curves of similar shape were found, but the small differences between fetal and

  3. Intersstellar absorption lines between 2000 and 3000 A in nearby stars observed with BUSS. [Balloon Borne Ultraviolet Spectrophotometer

    Science.gov (United States)

    De Boer, K. S.; Lenhart, H.; Van Der Hucht, K. A.; Kamperman, T. M.; Kondo, Y.

    1986-01-01

    Spectra obtained between 2000 and 3000 A with the Balloon Borne Ultraviolet Spectrophotometer (BUSS) payload were examined for interstellar absorption lines. In bright stars, with spectral types between O9V and F5V, such lines were measured of Mg I, Mg II, Cr II, Mn II, Fe II and Zn II, with Cr II and Zn II data of especially high quality. Column densities were derived and interstellar abundances were determined for the above species. It was found that metal depletion increases with increasing E(B-V); Fe was most affected and Zn showed a small depletion for E(B-V) greater than 0.3 towards Sco-Oph. The metal column densities, derived for Alpha-And, Kappa-Dra, Alpha-Com, Alpha-Aql, and 29 Cyg were used to infer N(H I). It was shown that the ratio of Mg I to Na I is instrumental in determining the ionization structure along each line of sight. The spectra of Aql stars confirms the presence of large gas densities near Alpha-Oph. Moreover, data indicated that the Rho-Oph N(H I) value needs to be altered to 35 x 10 to the 20th/sq cm, based on observed ion ratios and analysis of the Copernicus L-alpha profile.

  4. Direct In Situ Mass Specific Absorption Spectra of Biomass Burning Particles Generated from Smoldering Hard and Softwoods.

    Science.gov (United States)

    Radney, James G; You, Rian; Zachariah, Michael R; Zangmeister, Christopher D

    2017-05-16

    Particles from smoldering biomass burning (BB) represent a major source of carbonaceous aerosol in the terrestrial atmosphere. In this study, mass specific absorption spectra of laboratory-generated smoldering wood particles (SWP) from 3 hardwood and 3 softwood species were measured in situ. Absorption data spanning from λ = 500 to 840 nm were collected using a photoacoustic spectrometer coupled to a supercontinuum laser with a tunable wavelength and bandwidth filter. SWP were size- (electrical mobility) and mass-selected prior to optical characterization allowing data to be reported as mass-specific absorption cross sections (MAC). The median measured MAC at λ = 660 nm for smoldering oak particles was 1.1 (0.57/1.8) × 10 -2 m 2 g -1 spanning from 83 femtograms (fg) to 517 fg (500 nm ≤ mobility diameter ≤950 nm), MAC values in parentheses are the 16 th and 84 th percentiles of the measured data (i.e., 1σ). The collection of all six wood species (Oak, Hickory, Mesquite, Western redcedar, Baldcypress, and Blue spruce) had median MAC values ranging from 1.4 × 10 -2 m 2 g -1 to 7.9 × 10 -2 m 2 g -1 at λ = 550 nm with absorption Ångström exponents (AAE) between 3.5 and 6.2. Oak, Western redcedar, and Blue spruce possessed statistically similar (p > 0.05) spectra while the spectra of Hickory, Mesquite, and Baldcypress were distinct (p < 0.01) as calculated from a point-by-point analysis using the Wilcox rank-sum test.

  5. Correlation between Soft X-ray Absorption and Emission Spectra of the Nitrogen Atoms within Imidazolium-Based Ionic Liquids.

    Science.gov (United States)

    Horikawa, Yuka; Tokushima, Takashi; Takahashi, Osamu; Hoke, Hiroshi; Takamuku, Toshiyuki

    2016-08-04

    Soft X-ray absorption spectroscopy (XAS) has been performed on the N K-edge of two imidazolium-based ionic liquids (ILs), 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([C2mim][TFSA]) and 1-ethyl-3-methylimidazolium bromide ([C2mim][Br]), to clarify the electronic structures of the ILs. Soft X-ray emission spectroscopy (XES) has also been applied to the ILs by excitation at various X-ray energies according to the XAS spectra. It was possible to fully associate the XAS peaks with the XES peaks. Additionally, both XAS and XES spectra of the ILs were well reproduced by the theoretical spectra for a single-molecule model on [C2mim](+) and [TFSA](-) using density functional theory. The assignments for the XAS and XES peaks of the ILs were accomplished from both experimental and theoretical approaches. The theoretical XAS and XES spectra of [C2mim](+) and [TFSA](-) did not significantly depend on the conformations of the ions. The reproducibility of the theoretical spectra for the single-molecule model suggested that the interactions between the cations and anions are very weak in the ILs, thus scarcely influencing the electronic structures of the nitrogen atoms.

  6. Observing broad-absorption line quasars with Spectrum-Rontgen-Gamma

    DEFF Research Database (Denmark)

    Singh, K.P.; Schnopper, H.W.; Westergaard, Niels Jørgen Stenfeldt

    1998-01-01

    Broad-absorption line quasars are found to have extremely weak soft X-ray emission when compared with other optically selected quasars. In the only example of PHL 5200 for which a detailed X-ray spectrum has been obtained with ASCA, strong absorption in the source appears to be responsible...... for the lack of soft Xray emission. Broad-band X-ray observations of a sample of BAL QSOs are proposed with a high throughput mission SPECTRUM-RONTGEN-GAMMA (SRG), to find out whether these sources are intrinsically weak over the entire bandwidth of X-rays or only in the soft X-rays due to absorption resulting...

  7. Theoretical UV absorption spectra of hydrodynamically escaping O{sub 2}/CO{sub 2}-rich exoplanetary atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Gronoff, G.; Mertens, C. J.; Norman, R. B. [NASA LaRC, Hampton, VA (United States); Maggiolo, R. [BIRA-IASB, Avenue Circulaire 3, 1180 Brussels (Belgium); Wedlund, C. Simon [Aalto University School of Electrical Engineering Department of Radio Science and Engineering, P.O. Box 13000, FI-00076 Aalto (Finland); Bell, J. [National Institute of Aerospace, Hampton, VA (United States); Bernard, D. [IPAG, Grenoble (France); Parkinson, C. J. [University of Michigan, MI (United States); Vidal-Madjar, A., E-mail: Guillaume.P.Gronoff@nasa.gov [Observatoire de Paris, Paris (France)

    2014-06-20

    Characterizing Earth- and Venus-like exoplanets' atmospheres to determine if they are habitable and how they are evolving (e.g., equilibrium or strong erosion) is a challenge. For that endeavor, a key element is the retrieval of the exospheric temperature, which is a marker of some of the processes occurring in the lower layers and controls a large part of the atmospheric escape. We describe a method to determine the exospheric temperature of an O{sub 2}- and/or CO{sub 2}-rich transiting exoplanet, and we simulate the respective spectra of such a planet in hydrostatic equilibrium and hydrodynamic escape. The observation of hydrodynamically escaping atmospheres in young planets may help constrain and improve our understanding of the evolution of the solar system's terrestrial planets' atmospheres. We use the dependency of the absorption spectra of the O{sub 2} and CO{sub 2} molecules on the temperature to estimate the temperature independently of the total absorption of the planet. Combining two observables (two parts of the UV spectra that have a different temperature dependency) with the model, we are able to determine the thermospheric density profile and temperature. If the slope of the density profile is inconsistent with the temperature, then we infer the hydrodynamic escape. We address the question of the possible biases in the application of the method to future observations, and we show that the flare activity should be cautiously monitored to avoid large biases.

  8. Predicted sound absorption coefficients of absorber materials lined in a chamber

    Directory of Open Access Journals (Sweden)

    Farhad Forouharmajd

    2014-01-01

    Full Text Available Aims: The present study was aimed to measurement of sound absorption coefficient of mineral wool and determination of their absorption ability. Materials and Methods: Mineral wool was used to find noise absorption coefficient. Random and normal sound absorption coefficient values were predicted. Then, the measures of transmission loss calculated as an overall value, for applied absorbent material and bare sheet metal. Results: The measured values of noise with one octave band frequency demonstrated an attenuation of 5.5-7 dB for these frequencies. The absorption coefficients of materials showed that mineral wool had more normal sound coefficients than its random sound absorption coefficient values. Conclusion: It can be concluded that predicted normal sound absorption coefficients of used mineral wool materials were near to the areas of standard line. It seems that the amount or thickness of absorbent lining was a main reason of noise reduction in low band frequencies. Mineral wool has a higher density and can provide better acoustical and insulating results than fiberglass. Besides, mineral wool doesn′t lose its insulating value when wet and has an outstanding resistance to fire.

  9. Donor-related optical absorption spectra in GaAs-(Ga,Al)As quantum wells: hydrostatic pressure effects

    International Nuclear Information System (INIS)

    Lopez, S.Y.; Duque, C.A.; Porras-Montenegro, N.

    2004-01-01

    Full text: Donor-related optical-absorption spectra for GaAs-(Ga,Al)As quantum wells under hydrostatic pressure are investigated. A variational procedure in the e effective-mass approximation is used in order to obtain binding energies and wave functions. As a general feature, we observe that the binding energy increases with the pressure and with the decreasing of the width of the well. The pressure-related Γ-X crossover has been taken into account in the whole calculation. For the low-pressure regime we observe a linear binding energy behavior, whereas for high pressure the main effect associated with the height of the barrier is the bending of the binding energy curves towards smaller values. Two special structures in the density of impurity states and in the donor-related optical-absorption spectra are observed: an edge associated with transitions involving impurities at the center of the well and a peak associated with transitions related to impurities at the edges of the quantum well. Also, we observe shifts to higher energies of the density of impurity states as a function of the binding energy, as well as changes in the intensity with a red shift of the absorption effect with the hydrostatic pressure. (author)

  10. Study of Unidentified Spectral Lines in the High-Resolution Spectra of Comet Machholz (C/2004Q2

    Directory of Open Access Journals (Sweden)

    Sung-Won Hwang

    2009-12-01

    Full Text Available We observed Comet Machholz (C/2004Q2 using the BOES (BOao Echelle Spectograph at the Bohyunsan Observatory on January 4, 2005. We have studied a wavelength range of 4800~8100 °A in order to investigate unidentified spectral lines in the high-resolution spectra of Machholz. We compared the Machholz spectra with the high-resolution spectra of previous comets: Swift-Tuttle, Brorsen-Metcalf, Austin, and 122P/de Vico. We identified many molecular lines, which are previously unknown; and these identifications will be useful information for studying high-resolution spectra of future comets.

  11. VizieR Online Data Catalog: QSOs narrow absorption line variability (Hacker+, 2013)

    Science.gov (United States)

    Hacker, T. L.; Brunner, R. J.; Lundgren, B. F.; York, D. G.

    2013-06-01

    Catalogues of 2,522 QAL systems and 33 variable NAL systems detected in SDSS DR7 quasars with repeat observations. The object identifiers, position coordinates, and plate-MJD-fibre designations are taken from the SpecObjAll table in the SDSS Catalogue Archive Server (CAS) while the quasar redshifts (zqso) are from Hewett & Wild (2010, Cat. J/MNRAS/405/2302). The absorption system redshift (zabs), system grade, and detected lines are outputs of the York et al. (2013, in. prep.) QAL detection pipeline. Some absorption lines are flagged based on alternate identifications (a), proximity of masked pixels (b), or questionable continuum fits (c). (3 data files).

  12. Line Identification of Atomic and Ionic Spectra of Holmium in the Near-UV. II. Spectra of Ho ii and Ho iii

    Energy Technology Data Exchange (ETDEWEB)

    Başar, Gö.; Güzelçimen, F.; Er, A.; Öztürk, I. K. [Faculty of Science, Department of Physics, Istanbul University, TR-34134 Vezneciler, Istanbul (Turkey); Al-Labady, N.; Özdalgiç, B. [Graduate School of Engineering and Sciences, Istanbul University, TR-34452 Beyazat, Istanbul (Turkey); Ak, T.; Bİlİr, S. [Faculty of Science, Department of Astronomy and Space Sciences, Istanbul University, 34119, Istanbul (Turkey); Tamanis, M.; Ferber, R. [Laser Centre, The University of Latvia, Rainis Boulevard 19, LV-1586 Riga (Latvia); Kröger, S., E-mail: ikanat@istanbul.edu.tr [Hochschule für Technik und Wirtschaft Berlin, Wilhelminenhofstr. 75A, D-12459 Berlin (Germany)

    2017-02-01

    Fourier Transform spectra of holmium (Ho) in the UV spectral range from 31,530 to 25,000 cm{sup −1} (317 to 400 nm) have been investigated, particularly focusing on the ionic lines. The distinction between the different degrees of ionization (I, II, and III) is based on differences in signal-to-noise ratios from two Ho spectra, which have been measured with different buffer gases, i.e., neon and argon. Based on 106 known Ho ii and 126 known Ho iii energy levels, 97 lines could be classified as transitions of singly ionized Ho and 9 lines could be classified as transitions of doubly ionized Ho. Of the 97 Ho ii lines, 6 have not been listed in the extant literature. Another 215 lines have been assigned to Ho ii, though they could not be classified on the basis of the known energy levels.

  13. Absorption spectra and Faraday effect in Cs2NaNdCl6 and Cs2NaPrCl6 crystals

    International Nuclear Information System (INIS)

    Ehdel'man, I.S.; Galanov, E.K.; Kokov, I.T.; Malakhovskij, A.V.; Anistratov, A.T.

    1985-01-01

    The paper is devoted to studying absorption spectra and the Faraday effect in Cs 2 NaNdCl 6 and Cs 2 NaPrCl 6 crystals. The absorption spectra and Faraday effect were measured at room temperature in the range of 9000-30000 cmsup(-1) (0.33-1.2 μm) in 0-10 kOe magnetic fields. The absorption spectra produced contain several groups of intense absorption bands resulted from intraconfiguration electron transitions in rare-earth cations. The Faraday spectra in the whole range studied for both crystals have the form of smoothly dipping curves when increasing wavelength. The form of these curves testifies to prevailing contribution of strong electron transitions lying in a nearer UV region to the Faraday effect

  14. New Constraints on Quasar Broad Absorption and Emission Line Regions from Gravitational Microlensing

    Energy Technology Data Exchange (ETDEWEB)

    Hutsemékers, Damien; Braibant, Lorraine; Sluse, Dominique [Institut d' Astrophysique et de Géophysique, Université de Liège, Liège (Belgium); Anguita, Timo [Departamento de Ciencias Fisicas, Universidad Andres Bello, Santiago (Chile); Goosmann, René, E-mail: hutsemekers@astro.ulg.ac.be [Observatoire Astronomique de Strasbourg, Université de Strasbourg, Strasbourg (France)

    2017-09-29

    Gravitational microlensing is a powerful tool allowing one to probe the structure of quasars on sub-parsec scale. We report recent results, focusing on the broad absorption and emission line regions. In particular microlensing reveals the intrinsic absorption hidden in the P Cygni-type line profiles observed in the broad absorption line quasar H1413+117, as well as the existence of an extended continuum source. In addition, polarization microlensing provides constraints on the scattering region. In the quasar Q2237+030, microlensing differently distorts the Hα and CIV broad emission line profiles, indicating that the low- and high-ionization broad emission lines must originate from regions with distinct kinematical properties. We also present simulations of the effect of microlensing on line profiles considering simple but representative models of the broad emission line region. Comparison of observations to simulations allows us to conclude that the Hα emitting region in Q2237+030 is best represented by a Keplerian disk.

  15. Nebular and auroral emission lines of [Cl III] in the optical spectra of planetary nebulae.

    Science.gov (United States)

    Keenan, F P; Aller, L H; Ramsbottom, C A; Bell, K L; Crawford, F L; Hyung, S

    2000-04-25

    Electron impact excitation rates in Cl III, recently determined with the R-matrix code, are used to calculate electron temperature (T(e)) and density (N(e)) emission line ratios involving both the nebular (5517.7, 5537.9 A) and auroral (8433.9, 8480.9, 8500.0 A) transitions. A comparison of these results with observational data for a sample of planetary nebulae, obtained with the Hamilton Echelle Spectrograph on the 3-m Shane Telescope, reveals that the R(1) = I(5518 A)/I(5538 A) intensity ratio provides estimates of N(e) in excellent agreement with the values derived from other line ratios in the echelle spectra. This agreement indicates that R(1) is a reliable density diagnostic for planetary nebulae, and it also provides observational support for the accuracy of the atomic data adopted in the line ratio calculations. However the [Cl iii] 8433.9 A line is found to be frequently blended with a weak telluric emission feature, although in those instances when the [Cl iii] intensity may be reliably measured, it provides accurate determinations of T(e) when ratioed against the sum of the 5518 and 5538 A line fluxes. Similarly, the 8500.0 A line, previously believed to be free of contamination by the Earth's atmosphere, is also shown to be generally blended with a weak telluric emission feature. The [Cl iii] transition at 8480.9 A is found to be blended with the He i 8480.7 A line, except in planetary nebulae that show a relatively weak He i spectrum, where it also provides reliable estimates of T(e) when ratioed against the nebular lines. Finally, the diagnostic potential of the near-UV [Cl iii] lines at 3344 and 3354 A is briefly discussed.

  16. Using of laser spectroscopy and chemometrics methods for identification of patients with lung cancer, patients with COPD and healthy people from absorption spectra of exhaled air

    Science.gov (United States)

    Bukreeva, Ekaterina B.; Bulanova, Anna A.; Kistenev, Yury V.; Kuzmin, Dmitry A.; Nikiforova, Olga Yu.; Ponomarev, Yurii N.; Tuzikov, Sergei A.; Yumov, Evgeny L.

    2014-11-01

    The results of application of the joint use of laser photoacoustic spectroscopy and chemometrics methods in gas analysis of exhaled air of patients with chronic respiratory diseases (chronic obstructive pulmonary disease and lung cancer) are presented. The absorption spectra of exhaled breath of representatives of the target groups and healthy volunteers were measured; the selection by chemometrics methods of the most informative absorption coefficients in scan spectra in terms of the separation investigated nosology was implemented.

  17. Upper limits for stratospheric H2O2 and HOCl from high resolution balloon-borne infrared solar absorption spectra

    Science.gov (United States)

    Larsen, J. C.; Rinsland, C. P.; Goldman, A.; Murcray, D. G.; Murcray, F. J.

    1985-01-01

    Solar absorption spectra from two stratospheric balloon flights have been analyzed for the presence of H2O2 and HOCl absorption in the 1230.0 to 1255.0 per cm region. The data were recorded at 0.02 per cm resolution during sunset with the University of Denver interferometer system on October 27, 1978 and March 23, 1981. Selected spectral regions were analyzed with the technique of nonlinear least squares spectral curve fitting. Upper limits of 0.33 ppbv for H2O2 and 0.36 ppbv for HOCl near 28 km are derived from the 1978 flight data while upper limits of 0.44 ppbv for H2O2 and 0.43 ppbv for HOCl at 29.5 km are obtained from the 1981 flight data.

  18. Continuum Fitting HST QSO Spectra

    Science.gov (United States)

    Tytler, David; Oliversen, Ronald J. (Technical Monitor)

    2002-01-01

    The Principal Component Analysis (PCA) method which we are using to fit and describe QSO spectra relies upon the fact that QSO continuum are generally very smooth and simple except for emission and absorption lines. To see this we need high signal-to-noise (S/N) spectra of QSOs at low redshift which have relatively few absorption lines in the Lyman-a forest. We need a large number of such spectra to use as the basis set for the PCA analysis which will find the set of principal component spectra which describe the QSO family as a whole. We have found that too few HST spectra have the required S/N and hence we need to supplement them with ground based spectra of QSOs at higher redshift. We have many such spectra and we have been working to make them suitable for this analysis. We have concentrated on this topic since 12/15/01.

  19. Ruthenium(II) chloro-bis(bipyridyl) complexes with substituted pyridine ligands: interpretation of their electronic absorption spectra

    International Nuclear Information System (INIS)

    Sizova, O.V.; Ershov, A.Yu.; Ivanova, N.V.; Shashko, A.D.; Kutejkina-Teplyakova, A.V.

    2003-01-01

    A number of complexes cis-[Ru(Bipy) 2 (L)(Cl)](BF 4 ), where Bipy-2,2'-bipyridine, L-pyridine, 4-aminopyridine, 4-picoline, nicotinamide, isonicotinamide, 3- and 4-cyanopyridine, 4,4'-bipyridine, trans-1,2-bis(4-pyridyl)ethylene, 4,4'-azopyridine, pyrazine, imidazole and NH 3 , were prepared. Using the CINDO-CI semiempirical method the energies and intensities of transition in electronic absorption spectra (EAS) of the complexes were calculated. It is shown that major differences in EAS of the compounds stem from position of transitions with charge transfer d π (Ru)→π*(L) [ru

  20. Absorption spectra of Ag and Au nanoparticles using density functional theory

    International Nuclear Information System (INIS)

    Elham Gharibshahi; Elias Saion; Hishamuddin Zainuddin

    2009-01-01

    Full text: The absorption of photons in metal nanoparticles has been modelled electromagnetically by Mei theory. In this work, the problem was resolved quantum mechanically using the density function theory. This new development is based on the ground-state energy functional of Thomas-Fermi-Dirac-Weizsaecker atomic system and the absorption function replacing the density function in the Euler-Lagrange equation. The total energy functional was computed numerically for isolated spherical Ag and Au nanoparticles having face-centered-cubic lattice primitive cell structure. The absorption peaks appear at 412, 414, and 417 nm for Ag nanoparticles and at 515, 517, and 520 nm for Au nanoparticles when simulated for particle size of 8, 12, and 20 nm respectively. (author)

  1. Line-shape asymmetry of water vapor absorption lines in the 720-nm wavelength region

    Science.gov (United States)

    Grossmann, Benoist E.; Browell, Edward V.

    1991-01-01

    Spectral line-shape analyses were performed for water vapor lines broadened by argon, oxygen, and xenon in the 720-nm wavelength region. A line-shape asymmetry was observed, which is attributed to statistical dependence or correlation between velocity- and state-changing collisions. The generalized (asymmetric) Galatry profile, which results from the soft-collision profile and includes correlation between velocity- and state-changing collisions, was fitted to the observed line shapes and was found to compare favorably with the observed data. The most prominent asymmetries were observed with xenon as the buffer gas.

  2. On-line monitoring of the crystallization process: relationship between crystal size and electrical impedance spectra

    International Nuclear Information System (INIS)

    Zhao, Yanlin; Yao, Jun; Wang, Mi

    2016-01-01

    On-line monitoring of crystal size in the crystallization process is crucial to many pharmaceutical and fine-chemical industrial applications. In this paper, a novel method is proposed for the on-line monitoring of the cooling crystallization process of L-glutamic acid (LGA) using electrical impedance spectroscopy (EIS). The EIS method can be used to monitor the growth of crystal particles relying on the presence of an electrical double layer on the charged particle surface and the polarization of double layer under the excitation of alternating electrical field. The electrical impedance spectra and crystal size were measured on-line simultaneously by an impedance analyzer and focused beam reflectance measurement (FBRM), respectively. The impedance spectra were analyzed using the equivalent circuit model and the equivalent circuit elements in the model can be obtained by fitting the experimental data. Two equivalent circuit elements, including capacitance ( C 2 ) and resistance ( R 2 ) from the dielectric polarization of the LGA solution and crystal particle/solution interface, are in relation with the crystal size. The mathematical relationship between the crystal size and the equivalent circuit elements can be obtained by a non-linear fitting method. The function can be used to predict the change of crystal size during the crystallization process. (paper)

  3. THE EMISSION-LINE SPECTRA OF MAJOR MERGERS: EVIDENCE FOR SHOCKED OUTFLOWS

    International Nuclear Information System (INIS)

    Soto, Kurt T.; Martin, C. L.; Prescott, M. K. M.; Armus, L.

    2012-01-01

    Using a spectral decomposition technique, we investigate the physical origin of the high-velocity emission-line gas in a sample of 39 gas-rich, ultraluminous infrared galaxy mergers. Regions with shock-like excitation were identified in two kinematically distinct regimes, characterized by broad (σ > 150 km s –1 ) and narrow linewidths (σ ≤ 150 km s –1 ). Here, we investigate the physical origin of the broad emission, which we show is predominantly excited by shocks with velocities of 200-300 km s –1 . Considering the large amount of extinction in these galaxies, the blueshift of the broad emission suggests an origin on the near side of the galaxy and therefore an interpretation as a galactic outflow. The large spatial extent of the broad, shocked emission component is generally inconsistent with an origin in the narrow-line region of an active galactic nucleus. The kinetic energy in the mass loss as well as the luminosity of the emission lines is consistent with the fraction of the supernova energy attributed to these mechanisms by shocked stellar winds. Since some shocks can be recognized in moderately high resolution, integrated spectra of nearby ultraluminous starbursts, the spectral fitting technique introduced in Soto and Martin may therefore be used to improve the accuracy of the physical properties measured for high-redshift galaxies from their (observed frame) infrared spectra.

  4. White line structure in the x-ray Lsub(III) absorption edge of holmium

    International Nuclear Information System (INIS)

    Agarwal, B.K.; Agarwal, B.R.K.

    1978-01-01

    The white line at the Ho Lsub(III) absorption edge has been recorded in Ho metal, Ho 2 O 3 and HoCl 3 . The white line structure in Ho 2 O 3 has been analysed by regarding it as due to the transition into bound states of the Lsub(III) excited ion. The extended fine structure has been used to obtain information on the bond lengths in the compounds. (author)

  5. Spectra Aerosol Light Scattering and Absorption for Laboratory and Urban Aerosol

    Science.gov (United States)

    Gyawali, Madhu S.

    Atmospheric aerosols considerably influence the climate, reduce visibility, and cause problems in human health. Aerosol light absorption and scattering are the important factors in the radiation transfer models. However, these properties are associated with large uncertainties in climate modeling. In addition, atmospheric aerosols widely vary in composition and size; their optical properties are highly wavelength dependent. This work presents the spectral dependence of aerosol light absorption and scattering throughout the ultraviolet to near-infrared regions. Data were collected in Reno, NV from 2008 to 2010. Also presented in this study are the aerosol optical and physical properties during carbonaceous aerosols and radiative effects study (CARES) conducted in Sacramento area during 2010. Measurements were made using photoacoustic instruments (PA), including a novel UV 355 nm PA of our design and manufacture. Comparative analyses are presented for three main categories: (1) aerosols produced by wildfires and traffic emissions, (2) laboratory-generated and wintertime ambient urban aerosols, and (3) urban plume and biogenic emissions. In these categories, key questions regarding the light absorption by secondary organic aerosols (SOA), so-called brown carbon (BrC), and black carbon (BC) will be discussed. An effort is made to model the emission and aging of urban and biomass burning aerosol by applying shell-core calculations. Multispectral PA measurements of aerosols light absorption and scattering coefficients were used to calculate the Angstrom exponent of absorption (AEA) and single scattering albedo (SSA). The AEA and SSA values were analyzed to differentiate the aerosol sources. The California wildfire aerosols exhibited strong wavelength dependence of aerosol light absorption with AEA as lambda -1 for 405 and 870 nm, in contrast to the relatively weak wavelength dependence of traffic emissions aerosols for which AEA varied approximately as lambda-1. By using

  6. ExoMol molecular line lists - XXVI: spectra of SH and NS

    Science.gov (United States)

    Yurchenko, Sergei N.; Bond, Wesley; Gorman, Maire N.; Lodi, Lorenzo; McKemmish, Laura K.; Nunn, William; Shah, Rohan; Tennyson, Jonathan

    2018-04-01

    Line lists for the sulphur-containing molecules SH (the mercapto radical) and NS are computed as part of the ExoMol project. These line lists consider transitions within the X 2Π ground state for 32SH, 33SH, 34SH and 32SD, and 14N32S, 14N33S, 14N34S, 14N36S and 15N32S. Ab initio potential energy (PEC) and spin-orbit coupling (SOC) curves are computed and then improved by fitting to experimentally observed transitions. Fully ab initio dipole moment curves (DMCs) computed at high level of theory are used to produce the final line lists. For SH, our fit gives a root-mean-square (rms) error of 0.03 cm-1 between the observed (vmax = 4, Jmax = 34.5) and calculated transitions wavenumbers; this is extrapolated such that all X 2Π rotational-vibrational-electronic (rovibronic) bound states are considered. For 32SH the resulting line list contains about 81 000 transitions and 2 300 rovibronic states, considering levels up to vmax = 14 and Jmax = 60.5. For NS the refinement used a combination of experimentally determined frequencies and energy levels and led to an rms fitting error of 0.002 cm-1. Each NS calculated line list includes around 2.8 million transitions and 31 000 rovibronic states with a vibrational range up to v = 53 and rotational range to J = 235.5, which covers up to 23 000 cm-1. Both line lists should be complete for temperatures up to 5000 K. Example spectra simulated using this line list are shown and comparisons made to the existing data in the CDMS database. The line lists are available from the CDS (http://cdsarc.u-strasbg.fr) and ExoMol (www.exomol.com) data bases.

  7. Complexes of uranyl with N-oxides of heterocyclic amines. Electron-vibrational absorption spectra

    International Nuclear Information System (INIS)

    Jezowska-Trzebiatowska, B.; Wieczorek, M.

    1977-01-01

    A number of coordination compounds formed by uranyl chloride and nitrate with N-oxides of heterocyclic amines have been prepared and characterized by spectral measurements in the absorption region 20000-50000 cm -1 . The electrons and vibronic transitions have been determined and discussed. (author)

  8. Vibrational absorption spectra, DFT and SCC-DFTB conformational study and analysis of [Leu]enkephalin

    DEFF Research Database (Denmark)

    Abdali, Salim; Niehaus, T.A.; Jalkanen, Karl J.

    2003-01-01

    The endogenous morphine-like pentapeptide, [Leu]enkephalin, which binds to the opiate receptor in the brain, spinal core and gut, is the subject of this study. Vibrational absorption (VA) measurements were carried out on [Leu] enkephalin in non-polar solvent, DMSO-D6 to stabilize the environment...

  9. Classification and individualization of black ballpoint pen inks using principal component analysis of UV-vis absorption spectra.

    Science.gov (United States)

    Adam, Craig D; Sherratt, Sarah L; Zholobenko, Vladimir L

    2008-01-15

    The technique of principal component analysis has been applied to the UV-vis spectra of inks obtained from a wide range of black ballpoint pens available in the UK market. Both the pen ink and material extracted from the ink line on paper have been examined. Here, principal component analysis characterised each spectrum within a group through the numerical loadings attached to the first few principal components. Analysis of the spectra from multiple measurements on the same brand of pen showed excellent reproducibility and clear discrimination between inks that was supported by statistical analysis. Indeed it was possible to discriminate between the pen ink and the ink line from all brands examined in this way, suggesting that the solvent extraction process may have an influence on these results. For the complete set of 25 pens, interpretation of the loadings for the first few principal components showed that both the pen inks and the extracted ink lines may be classified in an objective manner and in agreement with the results of parallel thin layer chromatography studies. Within each class almost all inks could be individualised. Further work has shown that principal component analysis may be used to identify a particular ink from a database of reference UV-vis spectra and a strategy for developing this approach is suggested.

  10. Occurrence and Global Properties of Narrow CIV lambda 1549 Absorption Lines in Moderate-Redshift Quasars

    DEFF Research Database (Denmark)

    Vestergaard, Marianne

    2003-01-01

    A statistical study is presented of (a) the frequency of narrow CIV lambda 1549 absorption lines in 1.5 ~50%) of narrow CIV absorbers is detected for the radio-quiet and radio-loud quasars, and a constant ~25% of all the quasars, irrespective of radio type display associated CIV absorbers stronger...... than a rest equivalent width of 0.5A. Both radio-quiet and radio-loud quasars with narrow absorption lines have systematically redder continua, especially strongly absorbed objects. There is evidence of inclination dependent dust reddening and absorption for the radio quasars. An additional key result...... is that the most strongly absorbed radio quasars have the largest radio source extent. This result is in stark contrast to a recent study of the low-frequency selected Molonglo survey in which a connection between the strength of the narrow absorbers and the (young) age of the radio source has been proposed...

  11. Absorption-line strengths of 18 late-type spiral galaxies observed with SAURON

    NARCIS (Netherlands)

    Ganda, Katia; Peletier, Reynier F.; McDermid, Richard M.; Falcon-Barroso, Jesus; de Zeeuw, P. T.; Bacon, Roland; Cappellari, Michele; Davies, Roger L.; Emsellem, Eric; Krajnovic, Davor; Kuntschner, Harald; Sarzi, Marc; van de Ven, Glenn

    2007-01-01

    We present absorption line strength maps for a sample of 18 Sb-Sd galaxies observed using the integral-field spectrograph SAURON operating at the William Herschel Telescope on La Palma, as part of a project devoted to the investigation of the kinematics and stellar populations of late-type spirals,

  12. Spectra of light absorption by phytoplankton pigments in the Baltic; conclusions to be drawn from a Gaussian analysis of empirical data

    Directory of Open Access Journals (Sweden)

    Dariusz Ficek

    2004-12-01

    Full Text Available Analysed by differential spectroscopy, 1208 empirical spectra of light absorption apl(λ by Baltic phytoplankton were spectrally decomposed into 26 elementary Gaussian component bands. At the same time the composition and concentrations of each of the 5 main groups of pigments (chlorophylls a, chlorophylls b, chlorophylls c, photosynthetic carotenoids and photoprotecting carotenoids were analysed in 782 samples by HPLC. Inspection of the correlations between the intensities of the 26 elementary absorption bands and the concentrations of the pigment groups resulted in given elementary bands being attributed to particular pigment groups and the spectra of the mass-specific absorption coefficients established for these pigment groups. Moreover, balancing the absorption effects due to these 5 pigment groups against the overall absorption spectra of phytoplankton suggested the presence of a sixth group of pigments, as yet unidentified (UP, undetected by HPLC. A preliminary mathematical description of the spectral absorption properties of these UP was established. Like some forms of phycobilins, these pigments are strong absorbers in the 450-650 nm spectral region. The packaging effect of pigments in Baltic phytoplankton was analysed statistically, then correlated with the concentration of chlorophyll a in Baltic water. As a result, a Baltic version of the algorithm of light absorption by phytoplankton could be developed. This algorithm can be applied to estimate overall phytoplankton absorption spectra and their components due to the various groups of pigments from a knowledge of their concentrations in Baltic water.

  13. TD-DFT Study of Absorption and Emission Spectra of 2-(2'-Aminophenyl)benzothiazole Derivatives in Water.

    Science.gov (United States)

    Manojai, Natthaporn; Daengngern, Rathawat; Kerdpol, Khanittha; Kungwan, Nawee; Ngaojampa, Chanisorn

    2017-03-01

    Reduction of aromatic azides to amines is an important property of hydrogen sulphide (H 2 S) which is useful in fluorescence microscopy and H 2 S probing in cells. The aim of this work is to study the substituent effect on the absorption and emission spectra of 2-(2'-aminophenyl)benzothiazole (APBT) in order to design APBT derivatives for the use of H 2 S detection. Absorption and emission spectra of APBT derivatives in aqueous environment were calculated using density functional theory (DFT) and time-dependent DFT (TD-DFT) at B3LYP/6-311+G(d,p) level. The computed results favoured the substitution of strong electron-donating group on the phenyl ring opposite to the amino group for their large Stokes' shifts and emission wavelengths of over 600 nm. Also, three designed compounds were suggested as potential candidates for the fluorescent probes. Such generalised guideline learnt from this work can also be useful in further designs of other fluorescent probes of H 2 S in water.

  14. ExoMol molecular line lists - XXIII. Spectra of PO and PS

    Science.gov (United States)

    Prajapat, Laxmi; Jagoda, Pawel; Lodi, Lorenzo; Gorman, Maire N.; Yurchenko, Sergei N.; Tennyson, Jonathan

    2017-12-01

    Comprehensive line lists for phosphorus monoxide (31P16O) and phosphorus monosulphide (31P32S) in their X 2Π electronic ground state are presented. The line lists are based on new ab initio potential energy (PEC), spin-orbit (SOC) and dipole moment (DMC) curves computed using the MRCI+Q-r method with aug-cc-pwCV5Z and aug-cc-pV5Z basis sets. The nuclear motion equations (i.e. the rovibronic Schrödinger equations for each molecule) are solved using the program DUO. The PECs and SOCs are refined in least-squares fits to available experimental data. Partition functions, Q(T), are computed up to T = 5000 K, the range of validity of the line lists. These line lists are the most comprehensive available for either molecule. The characteristically sharp peak of the Q-branches from the spin-orbit split components gives useful diagnostics for both PO and PS in spectra at infrared wavelengths. These line lists should prove useful for analysing observations and setting up models of environments such as brown dwarfs, low-mass stars, O-rich circumstellar regions and potentially for exoplanetary retrievals. Since PS is yet to be detected in space, the role of the two lowest excited electronic states (a 4Π and B 2Π) are also considered. An approximate line list for the PS X-B electronic transition, which predicts a number of sharp vibrational bands in the near ultraviolet, is also presented. The line lists are available from the CDS (http://cdsarc.u-strasbg.fr) and ExoMol (www.exomol.com) data bases.

  15. Fine hematite particles of Martian interest: absorption spectra and optical constants

    International Nuclear Information System (INIS)

    Marra, A C; Blanco, A; Fonti, S; Jurewicz, A; Orofino, V

    2005-01-01

    Hematite is an iron oxide very important for the study of climatic evolution of Mars. It can occur in two forms: red and grey, mainly depending on the granulometry of the samples. Spectra of bright regions of Mars suggest the presence of red hematite particles. Moreover the Thermal Emission Spectrometer (TES), on board the Mars Global Surveyor mission, has discovered a deposit of crystalline grey hematite in Sinus Meridiani. TES spectra of that Martian region exhibit features at about 18, 23 and 33 μm that are consistent with hematite. Coarse grey hematite is considered strong evidence for longstanding water, while it is unknown whether the formation of fine-grained red hematite requires abundant water. Studies are needed in order to further characterize the spectral properties of the two kinds of hematite. For this reason we have analyzed a sample of submicron hematite particles in the 6.25-50 μm range in order to study the influence of particles size and shape on the infrared spectra. The optical constants of a particulate sample have been derived and compared with published data concerning bulk samples of hematite. Our results seem to indicate that particle shape is an important factor to take into account for optical constants derivation

  16. Simultaneous infrared and UV-visible absorption spectra of matrix-isolated carbon vapor

    Science.gov (United States)

    Kurtz, Joe; Huffman, Donald R.

    1989-01-01

    Carbon molecules were suggested as possible carriers of the diffuse interstellar bands. In particular, it was proposed that the 443 nm diffuse interstellar band is due to the same molecule which gives rise to the 447 nm absorption feature in argon matrix-isolated carbon vapor. If so, then an associated C-C stretching mode should be seen in the IR. By doing spectroscopy in both the IR and UV-visible regions on the same sample, the present work provides evidence for correlating UV-visible absorption features with those found in the IR. Early data indicates no correlation between the strongest IR feature (1997/cm) and the 447 nm band. Correlation with weaker IR features is being investigated.

  17. Impact of line parameter database and continuum absorption on GOSAT TIR methane retrieval

    Science.gov (United States)

    Yamada, A.; Saitoh, N.; Nonogaki, R.; Imasu, R.; Shiomi, K.; Kuze, A.

    2017-12-01

    The current methane retrieval algorithm (V1) at wavenumber range from 1210 cm-1 to 1360 cm-1 including CH4 ν 4 band from the thermal infrared (TIR) band of Thermal and Near-infrared Sensor for Carbon Observation Fourier Transform Spectrometer (TANSO-FTS) onboard Greenhouse Gases Observing Satellite (GOSAT) uses LBLRTM V12.1 with AER V3.1 line database and MT CKD 2.5.2 continuum absorption model to calculate optical depth. Since line parameter databases have been updated and the continuum absorption may have large uncertainty, the purpose of this study is to assess the impact on {CH}4 retrieval from the choice of line parameter databases and the uncertainty of continuum absorption. We retrieved {CH}4 profiles with replacement of line parameter database from AER V3.1 to AER v1.0, HITRAN 2004, HITRAN 2008, AER V3.2, or HITRAN 2012 (Rothman et al. 2005, 2009, and 2013. Clough et al., 2005), we assumed 10% larger continuum absorption coefficients and 50% larger temperature dependent coefficient of continuum absorption based on the report by Paynter and Ramaswamy (2014). We compared the retrieved CH4 with the HIPPO CH4 observation (Wofsy et al., 2012). The difference from HIPPO observation of AER V3.2 was the smallest and 24.1 ± 45.9 ppbv. The differences of AER V1.0, HITRAN 2004, HITRAN 2008, and HITRAN 2012 were 35.6 ± 46.5 ppbv, 37.6 ± 46.3 ppbv, 32.1 ± 46.1 ppbv, and 35.2 ± 46.0 ppbv, respectively. Maximum {CH}4 retrieval differences were -0.4 ppbv at the layer of 314 hPa when we used 10% larger absorption coefficients of {H}2O foreign continuum. Comparing AER V3.2 case to HITRAN 2008 case, the line coupling effect reduced difference by 8.0 ppbv. Line coupling effects were important for GOSAT TIR {CH}4 retrieval. Effects from the uncertainty of continuum absorption were negligible small for GOSAT TIR CH4 retrieval.

  18. The effect of zinc ion on the absorption and emission spectra of glutathione derivative: predication by ab initio and DFT methods.

    Science.gov (United States)

    Liu, Jianhua; Ma, Jie; Zhang, Hua; Wang, Haijun

    2012-06-01

    Relying on the reaction of o-phthalaldehyde (OPA) with glutathione (GSH) to form a highly fluorescence derivative GSH-OPA has been widely used to measure reduced glutathione. In order to better understand spectra property of the GSH-OPA and the effect of zinc ion on it, the ground and the lowest singlet excited state properties, the electronic absorption and emission spectra are predicted by ab initio and DFT methods. The absorption spectra are simulated using time dependent DFT method (TD-DFT) whereas the emission spectra are approximated by optimizing the lowest singlet excited state by HF/CI-Singles and then subsequently using this geometry for the TD-DFT calculations. The solvent effects on transition energies have been described within the conductor-like polarizable continuum model (CPCM). The calculated transition energies (absorption and emission) are in agreement with available experimental information. Copyright © 2012 Elsevier B.V. All rights reserved.

  19. Emission from water vapor and absorption from other gases at 5-7.5 μm in Spitzer-IRS Spectra Of Protoplanetary Disks

    Energy Technology Data Exchange (ETDEWEB)

    Sargent, B. A. [Center for Imaging Science and Laboratory for Multiwavelength Astrophysics, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623 (United States); Forrest, W.; Watson, Dan M.; Kim, K. H.; Richter, I.; Tayrien, C. [Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627 (United States); D' Alessio, P.; Calvet, N. [Department of Astronomy, The University of Michigan, 500 Church Street, 830 Dennison Building, Ann Arbor, MI 48109 (United States); Furlan, E. [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Green, J. [Department of Astronomy, University of Texas, 1 University Station, Austin, TX 78712 (United States); Pontoppidan, K., E-mail: baspci@rit.edu [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

    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.

  20. Infrared absorption spectra of t-HNOH radicals generated on VUV irradiation of NO in solid hydrogen.

    Science.gov (United States)

    Wu, Yu-Jong; Lin, Meng-Yeh; Hsu, Sheng-Chuan; Cheng, Bing-Ming

    2009-04-14

    Photoproduct signature: Irradiation of solid hydrogen near 3 K containing NO with vacuum-UV light from synchrotron radiation yields new infrared absorption lines at 1241.7, 1063.6 and 726.2 cm(-1) (see figure). These new lines are assigned to vibrational modes of t-HNOH. This photoproduct is formed from electronically excited NO reacting with neighboring hydrogen in the solid sample.Irradiation of solid H(2) near 3 K containing NO with vacuum-ultraviolet light from a synchrotron yields new infrared absorption lines at 1241.7, 1063.6 and 726.2 cm(-1). The structures of four possible structural isomers: H(2)NO, t-HNOH, c-HNOH and NOH(2), their vibrational wavenumbers, IR intensities and D-isotopic shifts are calculated with density-functional theory according to B3LYP and PW91PW91/aug-cc-pVTZ methods. Based on the results of those calculations and of experiments with deuterium labeling, we assign the new lines to nu(4) (cis bending), nu(5) (N==O stretching) and nu(6) (out-of-plane deformation) modes, respectively, of t-HNOH. This photoproduct is formed through reaction of electronically excited NO with neighboring H(2) in the solid sample.

  1. Application of Tsallis functions for analysis of line shapes in electron magnetic resonance spectra of magnetic nanoparticles

    Science.gov (United States)

    Koksharov, Yu. A.

    2015-10-01

    An effective electron magnetic resonance study of nanoparticles requires, in addition to an adequate theory (which is absent nowadays), standard spectral characteristics making it possible to compare the spectra. For characterizing the electron magnetic resonance spectra of magnetic nanoparticles, it has been proposed to use the decomposition of the spectra using the parameters of Tsallis distributions (lines with smoothly varying shapes). This method has been tested on a two-component spectrum of colloidal magnetite nanoparticles and on poorly resolved broad spectra of iron-containing nanoparticles stabilized on microgranules.

  2. Confirmation of Enhanced Dwarf-sensitive Absorption Features in the Spectra of Massive Elliptical Galaxies: Further Evidence for a Non-universal Initial Mass Function

    Science.gov (United States)

    van Dokkum, Pieter G.; Conroy, Charlie

    2011-07-01

    We recently found that massive cluster elliptical galaxies have strong Na I λ8183, 8195 and FeH λ9916 Wing-Ford band absorption, indicating the presence of a very large population of stars with masses clusters associated with M31. These globular clusters have similar metallicities, abundance ratios, and ages as massive elliptical galaxies but their low dynamical mass-to-light ratios rule out steep stellar initial mass functions (IMFs). From high-quality Keck spectra we find that the dwarf-sensitive absorption lines in globular clusters are significantly weaker than in elliptical galaxies and consistent with normal IMFs. The differences in the Na I and Wing-Ford indices are 0.027 ± 0.007 mag and 0.017 ± 0.006 mag, respectively. We directly compare the two classes of objects by subtracting the averaged globular cluster spectrum from the averaged elliptical galaxy spectrum. The difference spectrum is well fit by the difference between a stellar population synthesis model with a bottom-heavy IMF and one with a bottom-light IMF. We speculate that the slope of the IMF may vary with velocity dispersion, although it is not yet clear what physical mechanism would be responsible for such a relation.

  3. Interpretation of x-ray absorption spectra in compounds with configurational disorder

    International Nuclear Information System (INIS)

    Kuzmin, A.; Dalba, G.; Fornasini, P.; Rocca, F.; Sipr, O.

    2005-01-01

    Full text: X-ray absorption spectroscopy (EXAFS and XANES) provides with unique information on electronic, atomic and dynamic structure of materials. Standard EXAFS and XANES analysis is based on relatively simple structural models as Gaussian / normal distribution. However, there are many compounds as glasses and nanocrystalline materials in which atoms of the same type occupy structural sites with different local environments. Therefore, special approach is required to access properly the case of configurational disorder. In this work we present recent developments for such problem

  4. Carbon dioxide laser absorption spectra and low ppb photoacoustic detection of hydrazine fuels.

    Science.gov (United States)

    Loper, G L; Calloway, A R; Stamps, M A; Gelbwachs, J A

    1980-08-15

    Absorption cross-section data are reported for the toxic rocket fuels hydrazine, monomethylhydrazine, and unsymmetrical dimethylhydrazine (UDMH), as well as for their selected air oxidation products dimethylamine, trimethylamine, and methanol at up to seventy-eight CO(2) laser wavelengths each. These data are important for the assessment of the capability of CO(2) laser-based spectroscopic techniques for monitoring low levels of hydrazine-fuel vapors in the ambient air. Interference-free detection sensitivities of <30 ppb have been demonstrated for UDMH using a laboratory photoacoustic detection system.

  5. X-Ray Absorption Spectra of Water from First Principles Calculations

    International Nuclear Information System (INIS)

    Prendergast, David; Galli, Giulia

    2006-01-01

    We present a series of ab initio calculations of the x-ray absorption cross section (XAS) of ice and liquid water at ambient conditions. Our results show that all available experimental data and theoretical results are consistent with the standard model of the liquid as comprising molecules with approximately four hydrogen bonds. Our simulations of ice XAS including the lowest lying excitonic state are in excellent agreement with experiment and those of a quasitetrahedral model of water are in reasonable agreement with recent measurements. Hence we propose that the standard, quasitetrahedral model of water, although approximate, represents a reasonably accurate description of the local structure of the liquid

  6. Scaled-Absorption and Recurrence Spectra of Argon in an Electric Field Using Two Photon Excitation

    Science.gov (United States)

    Wright, J. D.; Huang, W.; Flores-Rueda, H.; Morgan, T. J.

    2001-05-01

    For multi-electron atoms in an electric field, low angular momentum Rydberg electrons strongly interact with the atomic core causing scattering which can be associated with the presence of chaos. The photoabsorption spectra exhibits extraordinary complex structure but is still in principle interpretable semiclassically using closed orbit theory and semiclassical S-matrix theory [1]. Previously we measured the scaled-photoabsorption and recurrence spectra of argon in an electric field, using single uv-photon excitation from a metastable state [2]. We have extended these measurements to two photon excitation from the same initial state, which allows access to different angular momentum states. The effect of multi-photon excitation on the structure of the recurrence spectrum and its subsequent semiclassical interpretation will be presented. Work supported by the National Science Foundation. [1] B. E. Granger and C. H. Greene, Phys.Rev.A 62, 12511 (2000) [2] H. Flores-Rueda, J. D. Wright, W. Huang, T. J. Morgan, Bull. Am. Phys. Soc. 45, 94 (2000)

  7. Monte Carlo simulations of the detailed iron absorption line profiles from thermal winds in X-ray binaries

    Science.gov (United States)

    Tomaru, Ryota; Done, Chris; Odaka, Hirokazu; Watanabe, Shin; Takahashi, Tadayuki

    2018-05-01

    Blueshifted absorption lines from highly ionized iron are seen in some high inclination X-ray binary systems, indicating the presence of an equatorial disc wind. This launch mechanism is under debate, but thermal driving should be ubiquitous. X-ray irradiation from the central source heats disc surface, forming a wind from the outer disc where the local escape velocity is lower than the sound speed. The mass-loss rate from each part of the disc is determined by the luminosity and spectral shape of the central source. We use these together with an assumed density and velocity structure of the wind to predict the column density and ionization state, then combine this with a Monte Carlo radiation transfer to predict the detailed shape of the absorption (and emission) line profiles. We test this on the persistent wind seen in the bright neutron star binary GX 13+1, with luminosity L/LEdd ˜ 0.5. We approximately include the effect of radiation pressure because of high luminosity, and compute line features. We compare these to the highest resolution data, the Chandra third-order grating spectra, which we show here for the first time. This is the first physical model for the wind in this system, and it succeeds in reproducing many of the features seen in the data, showing that the wind in GX13+1 is most likely a thermal-radiation driven wind. This approach, combined with better streamline structures derived from full radiation hydrodynamic simulations, will allow future calorimeter data to explore the detail wind structure.

  8. Monte-Carlo simulations of the detailed iron absorption line profiles from thermal winds in X-ray binaries

    Science.gov (United States)

    Tomaru, Ryota; Done, Chris; Odaka, Hirokazu; Watanabe, Shin; Takahashi, Tadayuki

    2018-02-01

    Blue-shifted absorption lines from highly ionised iron are seen in some high inclination X-ray binary systems, indicating the presence of an equatorial disc wind. This launch mechanism is under debate, but thermal driving should be ubiquitous. X-ray irradiation from the central source heats disc surface, forming a wind from the outer disc where the local escape velocity is lower than the sound speed. The mass loss rate from each part of the disc is determined by the luminosity and spectral shape of the central source. We use these together with an assumed density and velocity structure of the wind to predict the column density and ionisation state, then combine this with a Monte-Carlo radiation transfer to predict the detailed shape of the absorption (and emission) line profiles. We test this on the persistent wind seen in the bright neutron star binary GX 13+1, with luminosity L/LEdd ˜ 0.5. We approximately include the effect of radiation pressure because of high luminosity, and compute line features. We compare these to the highest resolution data, the Chandra third order grating spectra, which we show here for the first time. This is the first physical model for the wind in this system, and it succeeds in reproducing many of the features seen in the data, showing that the wind in GX13+1 is most likely a thermal-radiation driven wind. This approach, combined with better streamline structures derived from full radiation hydrodynamic simulations, will allow future calorimeter data to explore the detail wind structure.

  9. Absorption lines from magnetically driven winds in X-ray binaries

    Science.gov (United States)

    Chakravorty, S.; Petrucci, P.-O.; Ferreira, J.; Henri, G.; Belmont, R.; Clavel, M.; Corbel, S.; Rodriguez, J.; Coriat, M.; Drappeau, S.; Malzac, J.

    2016-05-01

    Context. High resolution X-ray spectra of black hole X-ray binaries (BHBs) show blueshifted absorption lines suggesting the presence of outflowing winds. Furthermore, observations show that the disk winds are equatorial and they occur in the Softer (disk dominated) states of the outburst and are less prominent or absent in the Harder (power-law dominated) states. Aims: We want to test whether the self-similar magneto-hydrodynamic (MHD) accretion-ejection models can explain the observational results for accretion disk winds in BHBs. In our models, the density at the base of the outflow from the accretion disk is not a free parameter. This mass loading is determined by solving the full set of dynamical MHD equations without neglecting any physical term. Thus, the physical properties of the outflow depend on and are controlled by the global structure of the disk. Methods: We studied different MHD solutions characterized by different values of the disk aspect ratio (ɛ) and the ejection efficiency (p). We also generate two kinds of MHD solutions depending on the absence (cold solution) or presence (warm solution) of heating at the disk surface. Such heating could be either from dissipation of energy due to MHD turbulence in the disk or from illumination of the disk surface. Warm solutions can have large (>0.1) values of p, which would imply larger wind mass loading at the base of the outflow. We use each of these MHD solutions to predict the physical parameters (distance, density, velocity, magnetic field, etc.) of an outflow. Motivated by observational results, we have put limits on the ionization parameter (ξ), column density, and timescales. Further constraints were derived for the allowed values of ξ from thermodynamic instability considerations, particularly for the Hard SED. These physical constraints were imposed on each of these outflows to select regions within it, which are consistent with the observed winds. Results: The cold MHD solutions are found to be

  10. Line strengths, A-factors and absorption cross-sections for fine structure lines in multiplets and hyperfine structure components in lines in atomic spectrometry - a user's guide

    International Nuclear Information System (INIS)

    Axner, Ove; Gustafsson, Joergen; Omenetto, Nicolo; Winefordner, James D.

    2004-01-01

    This work summarizes and elucidates a number of fundamental concepts in atomic spectrometry regarding the 'strengths' of transitions between various energy levels and states in atoms. Although several of the expressions and rules for line strengths of transitions reported here can be found, in one way or another, in various books dealing with atomic structure, atomic spectrometry or quantum mechanics, the treatment in such books can be variously complex and difficult to follow for a non-experienced reader. In addition, detailed information about transition-specific 'strengths' of transitions used to be restricted to line strengths, whereas most experiments rather need transition-specific A-factors or transition-specific absorption cross-sections. This work therefore aims at pointing out the most important aspects of the concept of 'strengths' of transitions between various energy levels and states in atoms by presenting explicit expressions for not only relative and absolute line strengths but also oscillator strengths (f-values), A-factors and absorption cross-sections, for transitions between fine structure levels within a multiplet as well as for hyperfine structure components within a line (i.e. between hyperfine structure levels), including their mutual relations, in a consistent and user-friendly manner. The work also recapitulates the most important summation rules for line strengths, oscillator strengths (f-values), A-factors and absorption cross-sections for lines within multiplets and hyperfine structure components within lines. Many of the expressions are illustrated with clear and intelligible examples. For the sake of clarity and completeness, the work also comprises a short review of the nomenclature for atomic structure and transitions

  11. Search for gravitational redshifted absorption lines in LMXB Serpens X-1

    Science.gov (United States)

    Yoneda, Hiroki; Done, Chris; Paerels, Frits; Takahashi, Tadayuki; Watanabe, Shin

    2018-04-01

    The equation of state for ultradense matter can be tested from observations of the ratio of mass to radius of neutron stars. This could be measured precisely from the redshift of a narrow line produced on the surface. X-rays bursts have been intensively searched for such features, but so far without detection. Here instead we search for redshifted lines in the persistent emission, where the accretion flow dominates over the surface emission. We discuss the requirements for narrow lines to be produced, and show that narrow absorption lines from highly ionized iron can potentially be observable in accreting low-mass X-ray binaries (LMXBs; low B field) that have either low spin or low inclination so that Doppler broadening is small. This selects Serpens X-1 as the only potential candidate persistent LMXB due to its low inclination. Including surface models in the broad-band accretion flow model predicts that the absorption line from He-like iron at 6.7 keV should be redshifted to ˜5.1-5.7 keV (10-15 km for 1.4 M⊙) and have an equivalent width of 0.8-8 eV for surface temperatures of 7-10 × 106 K. We use the high-resolution Chandra grating data to give a firm upper limit of 2-3 eV for an absorption line at ˜5 keV. We discuss possible reasons for this lack of detection (the surface temperature and the geometry of the boundary layer etc.). Future instruments with better sensitivity are required in order to explore the existence of such features.

  12. Evaluation of self-absorption coefficients of aluminum emission lines in laser-induced breakdown spectroscopy measurements

    International Nuclear Information System (INIS)

    El Sherbini, A.M.; El Sherbini, Th.M.; Hegazy, H.; Cristoforetti, G.; Legnaioli, S.; Palleschi, V.; Pardini, L.; Salvetti, A.; Tognoni, E.

    2005-01-01

    In quantitative Laser Induced Breakdown Spectroscopy (LIBS) measurements it is essential to account for the effect of self-absorption on the emission lines intensity. In order to quantify this effect, in this paper we propose a simple method for evaluating the ratio between the actual measured line intensity and the intensity expected in absence of self-absorption and, if necessary, correcting the effect of self-absorption on line intensity. The method, based on a homogeneous plasma model, is applicable when the plasma electron density is known and in particular to lines whose Stark broadening parameter is available

  13. UV absorption spectra, kinetics and mechanism for alkyl and alkyl peroxy radicals originating from t-butyl alcohol

    DEFF Research Database (Denmark)

    Langer, S.; Ljungström, E.; Sehested, J.

    1994-01-01

    Alkyl and alkyl peroxy radicals from 1-butyl alcohol (TBA), HOC (CH3)2CH2. and HOC(CH3)2CH2O2. have been studied in the ps phase at 298 K. Two techniques were used: pulse radiolysis UV absorption to measure the spectra and kinetics, and long path-length Fourier transform infrared spectroscopy (FTIR......) and k(HOC(CH3)2CH2O2. + NO2) were determined to be (4.9 +/- 0.9) X 10(-12) and (6.7 +/- 0.9) x 10(-12) cm3 molecule-1 s-1, respectively. In the FTIR experiments products were studied using chlorine-initiated oxidation in TBA/N2/Cl2 and TBA/N2/O2/Cl2 mixtures....

  14. INTERPRETATION OF AT-LINE SPECTRA FROM AFS-2 BATCH #3 FERROUS SULFAMATE TREATMENT

    Energy Technology Data Exchange (ETDEWEB)

    Kyser, E.; O' Rourke, P.

    2013-12-10

    Spectra from the “at-line” spectrometer were obtained during the ferrous sulfamate (FS) valence adjustment step of AFS-2 Batch #3 on 9/18/2013. These spectra were analyzed by mathematical principal component regression (PCR) techniques to evaluate the effectiveness of this treatment. Despite the complications from Pu(IV), we conclude that all Pu(VI) was consumed during the FS treatment, and that by the end of the treatment, about 85% was as Pu(IV) and about 15% was as Pu(III). Due to the concerns about the “odd” shape of the Pu(IV) peak and the possibility of this behavior being observed in the future, a follow-up sample was sent to SRNL to investigate this further. Analysis of this sample confirmed the previous results and concluded that it “odd” shape was due to an intermediate acid concentration. Since the spectral evidence shows complete reduction of Pu(VI) we conclude that it is appropriate to proceed with processing of this the batch of feed solution for HB-Line including the complexation of the fluoride with aluminum nitrate.

  15. Neutral atomic absorption lines and far-UV extinction: Possible implications for depletions and grain parameters

    Science.gov (United States)

    Welty, Daniel E.

    1990-01-01

    Researchers examine nine lines of sight within the Galaxy and one in the Large Magellanic Cloud (LMC) for which data on both neutral atomic absorption lines (Snow 1984; White 1986; Welty, Hobbs, and York 1989) and far UV extinction (Bless and Savage 1972; Jenkins, Savage, and Spitzer 1986) are available, in order to test the assumption that variations in gamma/alpha will cancel in taking ratios of the ionization balance equation, and to try to determine to what extent that assumption has affected the aforementioned studies of depletions and grain properties.

  16. UV spectroscopy including ISM line absorption: of the exciting star of Abell 35

    Science.gov (United States)

    Ziegler, M.; Rauch, T.; Werner, K.; Kruk, J. W.

    Reliable spectral analysis that is based on high-resolution UV observations requires an adequate, simultaneous modeling of the interstellar line absorption and reddening. In the case of the central star of the planetary nebula Abell 35, BD-22 3467, we demonstrate our current standard spectral-analysis method that is based on the Tübingen NLTE Model-Atmosphere Package (TMAP). We present an on- going spectral analysis of FUSE and HST/STIS observations of BD-22 3467.

  17. Wavelength Locking to CO2 Absorption Line-Center for 2-Micron Pulsed IPDA Lidar Application

    Science.gov (United States)

    Refaat, Tamer F.; Petros, Mulugeta; Antill, Charles W.; Singh, Upendra N.; Yu, Jirong

    2016-01-01

    An airborne 2-micron triple-pulse integrated path differential absorption (IPDA) lidar is currently under development at NASA Langley Research Center (LaRC). This IPDA lidar system targets both atmospheric carbon dioxide (CO2) and water vapor (H2O) column measurements. Independent wavelength control of each of the transmitted laser pulses is a key feature for the success of this instrument. The wavelength control unit provides switching, tuning and locking for each pulse in reference to a 2-micron CW (Continuous Wave) laser source locked to CO2 line-center. Targeting the CO2 R30 line center, at 2050.967 nanometers, a wavelength locking unit has been integrated using semiconductor laser diode. The CO2 center-line locking unit includes a laser diode current driver, temperature controller, center-line locking controller and CO2 absorption cell. This paper presents the CO2 center-line locking unit architecture, characterization procedure and results. Assessment of wavelength jitter on the IPDA measurement error will also be addressed by comparison to the system design.

  18. Optical absorption spectra and g factor of MgO: Mn2+explored by ab initio and semi empirical methods

    Science.gov (United States)

    Andreici Eftimie, E.-L.; Avram, C. N.; Brik, M. G.; Avram, N. M.

    2018-02-01

    In this paper we present a methodology for calculations of the optical absorption spectra, ligand field parameters and g factor for the Mn2+ (3d5) ions doped in MgO host crystal. The proposed technique combines two methods: the ab initio multireference (MR) and the semi empirical ligand field (LF) in the framework of the exchange charge model (ECM) respectively. Both methods of calculations are applied to the [MnO6]10-cluster embedded in an extended point charge field of host matrix ligands based on Gellé-Lepetit procedure. The first step of such investigations was the full optimization of the cubic structure of perfect MgO crystal, followed by the structural optimization of the doped of MgO:Mn2+ system, using periodic density functional theory (DFT). The ab initio MR wave functions approaches, such as complete active space self-consistent field (CASSCF), N-electron valence second order perturbation theory (NEVPT2) and spectroscopy oriented configuration interaction (SORCI), are used for the calculations. The scalar relativistic effects have also been taken into account through the second order Douglas-Kroll-Hess (DKH2) procedure. Ab initio ligand field theory (AILFT) allows to extract all LF parameters and spin-orbit coupling constant from such calculations. In addition, the ECM of ligand field theory (LFT) has been used for modelling theoptical absorption spectra. The perturbation theory (PT) was employed for the g factor calculation in the semi empirical LFT. The results of each of the aforementioned types of calculations are discussed and the comparisons between the results obtained and the experimental results show a reasonable agreement, which justifies this new methodology based on the simultaneous use of both methods. This study establishes fundamental principles for the further modelling of larger embedded cluster models of doped metal oxides.

  19. Förster resonance energy transfer, absorption and emission spectra in multichromophoric systems. I. Full cumulant expansions and system-bath entanglement.

    Science.gov (United States)

    Ma, Jian; Cao, Jianshu

    2015-03-07

    We study the Förster resonant energy transfer rate, absorption and emission spectra in multichromophoric systems. The multichromophoric Förster theory (MCFT) is determined from an overlap integral of generalized matrices related to the donor's emission and acceptor's absorption spectra, which are obtained via a full 2nd-order cumulant expansion technique developed in this work. We calculate the spectra and MCFT rate for both localized and delocalized systems, and calibrate the analytical 2nd-order cumulant expansion with the exact stochastic path integral method. We present three essential findings: (i) The role of the initial entanglement between the donor and its bath is found to be crucial in both the emission spectrum and the MCFT rate. (ii) The absorption spectra obtained by the cumulant expansion method are nearly identical to the exact spectra for both localized and delocalized systems, even when the system-bath coupling is far from the perturbative regime. (iii) For the emission spectra, the cumulant expansion can give reliable results for localized systems, but fail to provide reliable spectra of the high-lying excited states of a delocalized system, when the system-bath coupling is large and the thermal energy is small. This paper also provides a simple golden-rule derivation of the MCFT, reviews existing methods, and motivates further developments in the subsequent papers.

  20. Energy absorption and hardness of chair-side denture soft lining materials.

    Science.gov (United States)

    Tasopoulos, Theodorus; Jagger, Robert G; Jagger, Daryll C; Griffiths, Alex E

    2010-12-01

    The purpose of this study was to evaluate the hardness and energy absorption properties of four commercially available chairside silicone denture soft lining materials and to compare their properties with those of a heat-polymerized silicone denture liner. The denture lining materials investigated were four auto-polymerising silicone soft liners (GC Reline Soft, Ufigel SC, Elite Soft Relining and Tokuyama Sofreliner S) and a heat-polymerised silicone liner (Molloplast B). The soft liners were processed according to manufacturers' instructions. The specimens for hardness testing were 38 x 38 x 3 mm. The specimens for energy absorption test were 10 x 10 x 3 mm. In each test ten samples of each material were tested. There was strong evidence that Tokuyama Sofreliner S and, to a lesser extent, Ufigel SC, were less stiff and more resilient than Molloplast B. There was also strong evidence that both GC Reline Soft and Elite Soft Relining were harder than Molloplast B, while Ufigel SC and Tokuyama Sofreliner S were softer In conclusion differences existed between hardness and energy absorption properties of the soft lining materials.

  1. Probing autoionizing states of molecular oxygen with XUV transient absorption: Electronic-symmetry-dependent line shapes and laser-induced modifications

    Science.gov (United States)

    Liao, Chen-Ting; Li, Xuan; Haxton, Daniel J.; Rescigno, Thomas N.; Lucchese, Robert R.; McCurdy, C. William; Sandhu, Arvinder

    2017-04-01

    We used extreme ultraviolet (XUV) transient absorption spectroscopy to study the autoionizing Rydberg states of oxygen in an electronically- and vibrationally-resolved fashion. XUV pulse initiates molecular polarization and near-infrared pulse perturbs its evolution. Transient absorption spectra show positive optical-density (OD) change in the case of n s σg and n d πg autoionizing states of oxygen and negative OD change for n d σg states. Multiconfiguration time-dependent Hartree-Fock (MCTDHF) calculations are used to simulate the transient absorption and the resulting spectra and temporal evolution agree with experimental observations. We model the effect of near-infrared perturbation on molecular polarization and find that the laser-induced phase-shift model agrees with the experimental and MCTDHF results, while the laser-induced attenuation model does not. We relate the electronic-state-symmetry-dependent sign of the OD change to the Fano parameters of the static absorption line shapes.

  2. Collisional Processing Of Comet And Asteroid Surfaces: Velocity Effects On Absorption Spectra

    Science.gov (United States)

    Jensen, Elizabeth; Lederer, S. M.; Wooden, D. H.; Lindsay, S. S.; Nakamura-Messenger, K.; Keller, L. P.; Cintala, M. J.; Zolensky, M. E.

    2012-10-01

    A new paradigm has emerged where 3.9 Gyr ago, a violent reshuffling reshaped the placement of small bodies in the solar system (the Nice model). Surface properties of these objects may have been affected by collisions caused by this event, and by collisions with other small bodies since their emplacement. These impacts affect the spectroscopic observations of these bodies today. Shock effects (e.g., planar dislocations) manifest in minerals allowing astronomers to better understand geophysical impact processing that has occurred on small bodies. At the Experimental Impact Laboratory at NASA Johnson Space Center, we have impacted forsterite and enstatite across a range of velocities. We find that the amount of spectral variation, absorption wavelength, and full width half maximum of the absorbance peaks vary non-linearly with the velocity of the impact. We also find that the spectral variation increases with decreasing crystal size (single solid rock versus granular). Future analyses include quantification of the spectral changes with different impactor densities, temperature, and additional impact velocities. Results on diopside, fayalite, and magnesite can be found in Lederer et al., this meeting. Funding was provided by the NASA PG&G grant 09-PGG09-0115, NSF grant AST-1010012, and a Cottrell College Scholarship through the Research Corporation.

  3. Absorption Spectra of BaF2 Sm2O3, Sm, Gd, and Ho Plasmas

    Science.gov (United States)

    Martin, Michael; Bastiani-Ceccotti, Serena

    2009-11-01

    Knowledge of the opacities of high Z element plasmas is important in indirect drive ICF and the study of stellar evolution. There are few experimental measurements of this quantity, and its theoretical determination is difficult due to the number of possible bound electron configurations. This study aims to better the theoretical understanding of this parameter by looking at the 3d-4f transitions of BaF2, Sm2O3, Sm, Gd, and Ho plasmas at the LULI2000 facility. The plasmas are produced by radiative heating and are cold, 15 -- 40 eV, and relatively dense, ˜ .01gm/cm^3 A plasma is produced by a .5 ns laser pulse irradiating a gold hohlraum and then probed by an x-ray source created by a gold foil irradiated by a 10 ps laser pulse. The transmission is found with simultaneous source and absorption measurements by an x-ray spectrometer in the 8 - 20 å range We will compare the results with statistical atomic structure codes. From this experiment we will gain further insight into the spectral broadening of neighboring Z elements due to changing plasma temperature and into mixture thermodynamics. This is a first step towards an experimental study of astrophysical domains.

  4. Electronic absorption spectra and geometry of molecular ions generated from stilbene and related compounds, 3

    International Nuclear Information System (INIS)

    Suzuki, Hiroshi; Ogawa, Keiichiro; Shida, Tadamasa; Kira, Akira.

    1983-01-01

    The radical ions of (Z)-stilbene and its α,β-dialkyl derivatives were produced by γ-ray irradiation of the parent compounds in frozen matrices at 77 K, and their geometries were investigated by electronic absorption spectroscopy. While the relaxed geometries of the radical ions of (Z)-stilbene are probably similar to that of the neutral molecule, those of the radical ions of the α,β-dialkyl derivatives are appreciably different from those of the neutral molecules: The torsion angle of the central ethylenic bond is distinctly larger and that of each C-Ph bond is probably smaller in the radical ions than in the neutral molecules. On illumination the radical ions of (Z)-stilbene isomerize to the E isomers, but those of the α,β-dialkyl derivatives do not. A mechanism of the photoisomerization is proposed, and an interpretation of the difference in the photochemical behavior between the unsubstituted stilbene radical ions and the α,β-dialkyl derivatives is given. (author)

  5. Revisiting the total ion yield x-ray absorption spectra of liquid water microjets

    Energy Technology Data Exchange (ETDEWEB)

    Saykally, Richard J; Cappa, Chris D.; Smith, Jared D.; Wilson, Kevin R.; Saykally, Richard J.

    2008-02-16

    Measurements of the total ion yield (TIY) x-ray absorption spectrum (XAS) of liquid water by Wilson et al. (2002 J. Phys.: Condens. Matter 14 L221 and 2001 J. Phys. Chem. B 105 3346) have been revisited in light of new experimental and theoretical efforts by our group. Previously, the TIY spectrum was interpreted as a distinct measure of the electronic structure of the liquid water surface. However, our new results indicate that the previously obtained spectrum may have suffered from as yet unidentified experimental artifacts. Although computational results indicate that the liquid water surface should exhibit a TIY-XAS that is fundamentally distinguishable from the bulk liquid XAS, the new experimental results suggest that the observable TIY-XAS is actually nearly identical in appearance to the total electron yield (TEY-)XAS, which is a bulk probe. This surprising similarity between the observed TIY-XAS and TEY-XAS likely results from large contributions from x-ray induced electron stimulated desorption of ions, and does not necessarily indicate that the electronic structure of the bulk liquid and liquid surface are identical.

  6. Use of X-Ray Absorption Spectra as a ``Fingerprint'' of the Local Environment in Complex Chalcogenides

    Science.gov (United States)

    Branci, C.; Womes, M.; Lippens, P. E.; Olivier-Fourcade, J.; Jumas, J. C.

    2000-03-01

    The local environment of tin, titanium, iron, and sulfur in spinel compounds Cu2FeSn3S8 and Cu2FeTi3S8 was studied by X-ray absorption spectroscopy (XAS) at the titanium, iron, sulfur K edges, and the tin LI-edge. As detailed calculations of the electronic structure of these compounds are difficult to carry out due to the large number of atoms contained in the unit cell, the XAS spectra of the spinels are compared to those of relatively simple binary sulfides like SnS2, TiS2, and FeS. Indeed, the metal environments in these binary compounds are very similar to those in the spinels, and they can be considered good model compounds allowing the interpretation of electronic transitions observed in the spectra of quaternary phases. In the latter, the bottom of the conduction band is mainly formed by Sn 5s-S 3p, Sn 5p-S 3p antibonding states for the tin-based compounds and by Ti 3dt2g-S 3p, Ti 3deg-S 3p antibonding states for the titanium-based compounds. It it shown that the local environment of iron atoms remains unchanged when substituting tin with titanium atoms, according to a topotactic substitution.

  7. Spectroscopic and DFT study of solvent effects on the electronic absorption spectra of sulfamethoxazole in neat and binary solvent mixtures.

    Science.gov (United States)

    Almandoz, M C; Sancho, M I; Blanco, S E

    2014-01-24

    The solvatochromic behavior of sulfamethoxazole (SMX) was investigated using UV-vis spectroscopy and DFT methods in neat and binary solvent mixtures. The spectral shifts of this solute were correlated with the Kamlet and Taft parameters (α, β and π(*)). Multiple lineal regression analysis indicates that both specific hydrogen-bond interaction and non specific dipolar interaction play an important role in the position of the absorption maxima in neat solvents. The simulated absorption spectra using TD-DFT methods were in good agreement with the experimental ones. Binary mixtures consist of cyclohexane (Cy)-ethanol (EtOH), acetonitrile (ACN)-dimethylsulfoxide (DMSO), ACN-dimethylformamide (DMF), and aqueous mixtures containing as co-solvents DMSO, ACN, EtOH and MeOH. Index of preferential solvation was calculated as a function of solvent composition and non-ideal characteristics are observed in all binary mixtures. In ACN-DMSO and ACN-DMF mixtures, the results show that the solvents with higher polarity and hydrogen bond donor ability interact preferentially with the solute. In binary mixtures containing water, the SMX molecules are solvated by the organic co-solvent (DMSO or EtOH) over the whole composition range. Synergistic effect is observed in the case of ACN-H2O and MeOH-H2O, indicating that at certain concentrations solvents interact to form association complexes, which should be more polar than the individual solvents of the mixture. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Excited S 1 state dipole moments of nitrobenzene and p-nitroaniline from thermochromic effect on electronic absorption spectra

    Science.gov (United States)

    Kawski, A.; Kukliński, B.; Bojarski, P.

    2006-11-01

    The effect of temperature on the absorption spectra of nitrobenzene (NB) and p-nitroaniline (NA) in 1,2-dichloroethane was studied for temperature ranging from 295 K to 378 K and from 296 K to 408 K, respectively. With temperature increase the absorption bands of both compounds are blue shifted, which is caused by the decrease of permittivity ɛ and refractive index n. From the band shifts and by using the Bilot and Kawski theory [ L. Bilot, A. Kawski, Z. Naturforsch. 17a (1962) 621] the dipole moments in the excited singlet state μe = 6.59 D of NB and μe = 13.35 D of NA were determined. The influence of polarizability α, the Onsager cavity radius a and dipole moment in the ground state μg on the determined values of μe are discussed. A comparison of the obtained μe values with those of other authors is given. In the case of p-NA a strong intramolecular charge transfer (ICT) was confirmed.

  9. Influence of temperature on water and aqueous glucose absorption spectra in the near- and mid-infrared regions at physiologically relevant temperatures

    DEFF Research Database (Denmark)

    Jensen, P.S.; Bak, J.; Andersson-Engels, S.

    2003-01-01

    Near- and mid-infrared absorption spectra of pure water and aqueous 1.0 g/dL glucose solutions in the wavenumber range 8000-950 cm(-1) were measured in the temperature range 30-42 C in steps of 2 degreesC. Measurements were carried out with an FT-IR spectrometer and a variable pathlength...... degreesC water spectrum from the spectra measured at other temperatures. The difference spectra reveal that the effect of temperature is highest in the vicinity of the strong absorption bands, with a number of isosbestic points with no temperature dependence and relatively flat plateaus in between....... The change in water absorption associated with the addition of glucose has also been studied. An estimate of these effects is given and is related to the expected level of infrared signals from glucose in humans....

  10. Simultaneous measurement of quantum yield ratio and absorption ratio between acceptor and donor by linearly unmixing excitation-emission spectra.

    Science.gov (United States)

    Zhang, C; Lin, F; DU, M; Qu, W; Mai, Z; Qu, J; Chen, T

    2018-02-13

    Quantum yield ratio (Q A /Q D ) and absorption ratio (K A /K D ) in all excitation wavelengths used between acceptor and donor are indispensable to quantitative fluorescence resonance energy transfer (FRET) measurement based on linearly unmixing excitation-emission spectra (ExEm-spFRET). We here describe an approach to simultaneously measure Q A /Q D and K A /K D values by linearly unmixing the excitation-emission spectra of at least two different donor-acceptor tandem constructs with unknown FRET efficiency. To measure the Q A /Q D and K A /K D values of Venus (V) to Cerulean (C), we used a wide-field fluorescence microscope to image living HepG2 cells separately expressing each of four different C-V tandem constructs at different emission wavelengths with 435 nm and 470 nm excitation respectively to obtain the corresponding excitation-emission spectrum (S DA ). Every S DA was linearly unmixed into the contributions (weights) of three excitation-emission spectra of donor (W D ) and acceptor (W A ) as well as donor-acceptor sensitisation (W S ). Plot of W S /W D versus W A /W D for the four C-V plasmids from at least 40 cells indicated a linear relationship with 1.865 of absolute intercept (Q A /Q D ) and 0.273 of the reciprocal of slope (K A /K D ), which was validated by quantitative FRET measurements adopting 1.865 of Q A /Q D and 0.273 of K A /K D for C32V, C5V, CVC and VCV constructs respectively in living HepG2 cells. © 2018 The Authors Journal of Microscopy © 2018 Royal Microscopical Society.

  11. Potential chlorofluorocarbon replacements: OH reaction rate constants between 250 and 315 K and infrared absorption spectra

    Science.gov (United States)

    Garland, Nancy L.; Medhurst, Laura J.; Nelson, H. H.

    1993-12-01

    We measured the rate constant for reactions of the OH radical with several potential chlorofluorocarbon replacements over the temperature range 251-314 K using laser photolysis laser-induced fluorescence techniques. The compounds studied and Arrhenius parameters determined from fits to the measured rate constants are as follows: CHF2OCHF2 (E 134), k(T) = (5.4 ± 3.5) × 10-13 cm3 s-1 exp [(-3.1 ± 0.4 kcal mol-1)/RT]; CF3CH2CF3 (FC 236fa), k(T) = (2.0 ± 1.0) × 10-14 cm3 s-1 exp [(-1.8 ± 0.3 kcal mol-1)/RT]; CF3CHFCHF2 (FC 236ea), k(T) = (2.0 ± 0.9) × 10-13 cm3 s-1 exp [(-2.0 ± 0.3 kcal mol-1)/RT]; and CF3CF2CH2F (FC 236cb), k(T)= (2.6 ± 1.6) × 10-13 cm3 s-1 exp [(-2.2 ± 0.4 kcal mol-1)/RT]. The measured activation energies (2-3 kcal mol-1) are consistent with a mechanism of H atom abstraction. The tropospheric lifetimes, estimated from the measured OH reaction rates, and measured integrated infrared absorption cross sections over the range 770 to 1430 cm-1 suggest that E 134 and FC 236fa may have significant global warming potential, while FC 236ea and FC 236cb do not.

  12. L23 soft-x-ray emission and absorption spectra of Na

    International Nuclear Information System (INIS)

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

    1978-01-01

    The L 23 soft-x-ray emission (SXE) and soft-x-ray absorption (SXA) edges have been measured. The SXE edges were measured at temperatures between 85 and 380 K, and analyzed to obtain edge positions and widths. The widths increased from GAMMA/sub SXE/ = 100 meV at 85 K to 150 meV at 320 K and to 180 meV above the melting point at 380 K. Both SXE and SXA edges were measured at 100 K with the same spectrometer, and the data were analyzed to obtain values of the edge widths (GAMMA/sub SXE/ = 100 meV and GAMMA/sub SXA/ = 64 meV), of the many-body peaking parameter (α/sub SXE/ = 0.15 and α/sub SXA/ = 0.24), of the gap between the edges (E/sub g/ = 74 meV), and of the excess width of the emission edge [(ΔGAMMA) 2 = GAMMA 2 /sub SXE/ - GAMMA 2 /sub SXA/ = 5900 (meV) 2 ]. The values of E/sub g/ and (ΔGAMMA) 2 were used in the partial-lattice-relaxation theory of Almbladh to obtain a value of the core-hole lifetime broadening (GAMMA/sub 2p/ = 10 meV). We conclude that structure in the transition density of states, many-body effects, and lattice relaxation all have important effects on the edge structure, and suggest that rounding of the SXE edge by partial relaxation accounts for the smaller peaking parameter obtained from the SXE data as compared to the SXA data

  13. Measurements of size and composition of particles in polar stratospheric clouds from infrared solar absorption spectra

    International Nuclear Information System (INIS)

    Kinne, S.; Toon, O.B.; Toon, G.C.; Farmer, C.B.; Browell, E.V.; McCormick, M.P.

    1989-01-01

    The attenuation of solar radiation between 1.8- and 15-μm wavelength was measured with the airborne Jet Propulsion Laboratory Mark IV interferometer during the Airborne Antarctic Ozone Expedition in 1987. The measurements not only provide information about the abundance of stratospheric gases, but also about the optical depths of polar stratospheric clouds (PSCs) at wavelengths of negligible gas absorption. The spectral dependence of the PSC optical depth contains information about PSC particle size and particle composition. Thirty-three PSC cases were analyzed and categorized into two types. Type I clouds contain particles with radii of about 0.5 μm and nitric acid concentrations greater than 40%. Type II clouds contain particles composed of water ice with radii of 6 μm and larger. Cloud altitudes were determined from 1.064-μm backscattering observations of the airborne Langley DIAL lidar system. Based on the PSC geometrical thickness, both mass and particle density were estimated. Type I clouds typically had visible wavelength optical depths of about 0.008, mass densities of about 20 ppb, and about 2 particles/cm 3 . The observed type II clouds had optical depths of about 0.03, mass densities of about 400 ppb mass, and about 0.03 particles/cm 3 . The detected PSC type I clouds extended to altitudes of 21 km and were nearly in the ozone-depleted region of the polar stratosphere. The observed type II cases during September were predominantly found at altitudes below 15 km

  14. Emission Lines of O III in The Optical and Ultraviolet Spectra of Planetary Nebulae

    Science.gov (United States)

    Crawford, F. L.; Keenan, F. P.; Aggarwal, K. M.; Aller, L. H.; Feibelman, W. A.; Fisher, Richard R. (Technical Monitor)

    2000-01-01

    Recent R-matrix calculations of electron impact excitation rates in 0 III are used to calculate electron temperature and density-dependent emission line ratios R (sub 1) = I(4363 Angstroms)/ I(4960 Angstroms + 5007 Angstroms), R (sub 2) = I(1661 Angstroms + 1667 Angstroms)/ I(4960 Angstroms + 5007 Angstroms) and R (sub 3)= I(2322 Angstroms)/ I(1661 Angstroms + 1667 Angstroms), for a range of electron temperatures (7500 less than or equal to Te less than or equal to 30 000 K) and densities (10 (exp 4) less than or equal to N (sub e) less than or equal to 10 (exp 7) per cubic centimeters) applicable to gaseous nebulae. The ratio-ratio diagrams (R (sub 1), R (sub 2)) and (R (sub 1), R (sub 3)) should, in principle, allow the simultaneous determination of T (sub e) and N (sub e) from measurements of the 0 III features in a spectrum. Plasma parameters derived for a sample of high-excitation planetary nebulae from (R (sub 1), R (sub 2)) and (R (sub 1), R (sub 3)) measurements, produced using a combination of ultraviolet spectra obtained with the International Ultraviolet Explorer (IUE) and optical data from a number of observing runs, are found to show excellent internal consistency. They also show, in general, good agreement with the values of Te and Ne estimated from other line ratios in the nebulae, therefore providing observational support for the accuracy of the theoretical ratios and hence the atomic data adopted in their derivation.

  15. N IV emission lines in the ultraviolet spectra of gaseous nebulae

    Science.gov (United States)

    Keenan, F. P.; Ramsbottom, C. A.; Bell, K. L.; Berrington, K. A.; Hibbert, A.; Feibelman, W. A.; Blair, W. P.

    1995-01-01

    Theoretical electron density sensitive emission-line ratios, determined using electron impact excitation rates calculated with the R-matrix code, are presented for R = I(2s(sup 2) (1)S-2s2p 3P(sub 2))/I(2s(sup 2) (1)S-2s2p 3P(sub 1) = 1(1483 A)/I(1486 A) in N IV. These are found to be up to an order of magnitude different from those deduced by previous authors, principally due to the inclusion of excitation rates for transitions among the 2s2p (3)p fine-structure levels. The observed values of R for several planetary nebulae, symbiotic stars and the Cygnus Loop supernova remnant, measured from spectra obtained with the International Ultraviolet Explorer (IUE) satellite and the Hopkins Ultraviolet Explorer (HUT), lead to electron densities which are in excellent agreement with those deduced from line ratios in other species. This provides observational support for the accuracy of the atomic data adopted in the present calculations.

  16. Unshifted Metastable He I* Mini-broad Absorption Line System in the Narrow-line Type 1 Quasar SDSS J080248.18+551328.9

    Science.gov (United States)

    Ji, Tuo; Zhou, Hongyan; Jiang, Peng; Wang, Tinggui; Ge, Jian; Wang, Huiyuan; Komossa, S.; Hamann, Fred; Zuther, Jens; Liu, Wenjuan; Lu, Honglin; Zuo, Wenwen; Yang, Chenwei; Yuan, Weimin

    2015-02-01

    We report the identification of an unusual absorption-line system in the quasar SDSS J080248.18+551328.9 and present a detailed study of the system, incorporating follow-up optical and near-IR spectroscopy. A few tens of absorption lines are detected, including He I*, Fe II*, and Ni II*, which arise from metastable or excited levels, as well as resonant lines in Mg I, Mg II, Fe II, Mn II, and Ca II. All of the isolated absorption lines show the same profile of width Δv ~ 1500 km s-1 centered at a common redshift as that of the quasar emission lines, such as [O II], [S II], and hydrogen Paschen and Balmer series. With narrow Balmer lines, strong optical Fe II multiplets, and weak [O III] doublets, its emission-line spectrum is typical for that of a narrow-line Seyfert 1 galaxy (NLS1). We have derived reliable measurements of the gas-phase column densities of the absorbing ions/levels. Photoionization modeling indicates that the absorber has a density of n H ~ (1.0-2.5) × 105 cm-3 and a column density of N H ~ (1.0-3.2) × 1021 cm-2 and is located at R ~100-250 pc from the central supermassive black hole. The location of the absorber, the symmetric profile of the absorption lines, and the coincidence of the absorption- and emission-line centroid jointly suggest that the absorption gas originates from the host galaxy and is plausibly accelerated by stellar processes, such as stellar winds and/or supernova explosions. The implications for the detection of such a peculiar absorption-line system in an NLS1 are discussed in the context of coevolution between supermassive black hole growth and host galaxy buildup.

  17. Line Identification of Atomic and Ionic Spectra of Holmium in the Near-UV. Part I. Spectrum of Ho i

    Energy Technology Data Exchange (ETDEWEB)

    Al-Labady, N.; Özdalgiç, B. [Graduate School of Engineering and Sciences, Istanbul University, TR-34452 Beyazıt, Istanbul (Turkey); Er, A.; Güzelçimen, F.; Öztürk, I. K.; Başar, Gö. [Faculty of Science, Department of Physics, Istanbul University, TR-34134 Vezneciler, Istanbul (Turkey); Kröger, S. [Hochschule für Technik und Wirtschaft Berlin, Wilhelminenhofstr. 75A, D-12459 Berlin (Germany); Kruzins, A.; Tamanis, M.; Ferber, R., E-mail: ikanat@istanbul.edu.tr [Laser Centre, The University of Latvia, Rainis Boulevard 19, LV-1586 Riga (Latvia)

    2017-02-01

    The Fourier Transform spectra of a Holmium hollow cathode discharge lamp have been investigated in the UV spectral range from 25,000 up to 31,530 cm{sup −1} (317 to 400 nm). Two Ho spectra have been measured with neon and argon as buffer gases. Based on the intensity ratios from these two spectra, a distinction was made between atomic and ionic lines (ionic lines are discussed in an accompanying paper). Using the known Ho i energy levels, 71 lines could be classified as transitions of atomic Ho, 34 of which have not been published previously. Another 32 lines, which could not be classified, are listed in the literature and assigned as atomic Ho. An additional 370 spectral lines have been assigned to atomic Ho based on the signal-to-noise ratio in the two spectra measured under different discharge conditions, namely with buffer gases argon and neon, respectively. These 370 lines have not been previously listed in the literature.

  18. Ultrafast Time-Resolved Emission and Absorption Spectra of meso-Pyridyl Porphyrins upon Soret Band Excitation Studied by Fluorescence Up-Conversion and Transient Absorption Spectroscopy.

    Science.gov (United States)

    Venkatesh, Yeduru; Venkatesan, M; Ramakrishna, B; Bangal, Prakriti Ranjan

    2016-09-08

    A comprehensive study of ultrafast molecular relaxation processes of isomeric meso-(pyridyl) porphyrins (TpyPs) has been carried out by using femtosecond time-resolved emission and absorption spectroscopic techniques upon pumping at 400 nm, Soret band (B band or S2), in 4:1 dichloromethane (DCM) and tetrahydrofuran (THF) solvent mixture. By combined studies of fluorescence up-conversion, time-correlated single photon counting, and transient absorption spectroscopic techniques, a complete model with different microscopic rate constants associated with elementary processes involved in electronic manifolds has been reported. Besides, a distinct coherent nuclear wave packet motion in Qy state is observed at low-frequency mode, ca. 26 cm(-1) region. Fluorescence up-conversion studies constitute ultrafast time-resolved emission spectra (TRES) over the whole emission range (430-710 nm) starting from S2 state to Qx state via Qy state. Careful analysis of time profiles of up-converted signals at different emission wavelengths helps to reveal detail molecular dynamics. The observed lifetimes are as indicated: A very fast decay component with 80 ± 20 fs observed at ∼435 nm is assigned to the lifetime of S2 (B) state, whereas being a rise component in the region of between 550 and 710 nm emission wavelength pertaining to Qy and Qx states, it is attributed to very fast internal conversion (IC) occurring from B → Qy and B → Qx as well. Two distinct components of Qy emission decay with ∼200-300 fs and ∼1-1.5 ps time constants are due to intramolecular vibrational redistribution (IVR) induced by solute-solvent inelastic collisions and vibrational redistribution induced by solute-solvent elastic collision, respectively. The weighted average of these two decay components is assigned as the characteristic lifetime of Qy, and it ranges between 0.3 and 0.5 ps. An additional ∼20 ± 2 ps rise component is observed in Qx emission, and it is assigned to the formation time of

  19. Faint Object Spectrograph Spectra of the UV Emission Lines in NGC 5558: Detection of Strong Narrow Components

    Science.gov (United States)

    Crenshaw, D. Michael; Boggess, Albert; Wu, Chi-Chao

    1993-01-01

    Ultraviolet spectra of the Seyfert 1 galaxy NGC 5548 were obtained with the Faint Object Spectrograph (FOS) on the Hubble Space Telescope on 1992 July 5, when the UV continuum and broad emission lines were at their lowest ever observed level. The high resolution of the spectra, relative to previous UV observations, and the low state of NGC 5548 allow the detection and accurate measurement of strong narrow components of the emission lines of Ly alpha, C IV 1549, and C III 1909. Isolation of the UV narrow components enables a detailed comparison of narrow-line region (NLR) properties in Seyfert 1 and 2 galaxies, and removal of their contribution is important for studies of the broad-line region (BLR). Relative to the other narrow lines, C IV 1549 is much stronger in NGC 5548 than in Seyfert 2 galaxies, and Mg II 2798 is very weak or absent.

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

    Science.gov (United States)

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

    1986-08-01

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

  1. Extracting ion emission lines from femtosecond-laser plasma x-ray spectra heavily contaminated by spikes

    International Nuclear Information System (INIS)

    Gasilov, S. V.; Faenov, A. Ya.; Pikuz, T. A.; Villoresi, P.; Poletto, L.; Stagira, S.; Calegari, F.; Vozzi, C.; Nisoli, M.

    2007-01-01

    Nowadays charged-coupled device (CCD) detectors are widely used for the registration of multicharged ions x-ray spectra. These spectra are generated in a plasma during interaction of ultrashort, ultraintense laser pulses with solid targets. Strong parasitic radiation from the plasma affects CCD detectors and contaminates resulting spectra, so that spectral features can be completely covered by noise even during measurements with a very short accumulation time. In this work we propose a ''mean to median'' (M2M) algorithm for noise suppression in femtosecond laser plasma x-ray spectra. Series of spectra is necessary for the identification of corrupted data points by the developed method. The algorithm was tested with model spectra which reflect main features of experimental data. In practice we used it for extracting information about spectral lines of Ne-like Fe ions and He-like Al ions which allowed us to calculate plasma parameters. It is demonstrated that M2M method is able to clean spectra with more than 10% of corrupted pixels. Fluctuations in intensity of spectral lines induced by laser instability do not affect validity of the proposed method

  2. Accounting for nanometer-thick adventitious carbon contamination in X-ray absorption spectra of carbon-based materials.

    Science.gov (United States)

    Mangolini, Filippo; McClimon, J Brandon; Rose, Franck; Carpick, Robert W

    2014-12-16

    Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy is a powerful technique for characterizing the composition and bonding state of nanoscale materials and the top few nanometers of bulk and thin film specimens. When coupled with imaging methods like photoemission electron microscopy, it enables chemical imaging of materials with nanometer-scale lateral spatial resolution. However, analysis of NEXAFS spectra is often performed under the assumption of structural and compositional homogeneity within the nanometer-scale depth probed by this technique. This assumption can introduce large errors when analyzing the vast majority of solid surfaces due to the presence of complex surface and near-surface structures such as oxides and contamination layers. An analytical methodology is presented for removing the contribution of these nanoscale overlayers from NEXAFS spectra of two-layered systems to provide a corrected photoabsorption spectrum of the substrate. This method relies on the subtraction of the NEXAFS spectrum of the overlayer adsorbed on a reference surface from the spectrum of the two-layer system under investigation, where the thickness of the overlayer is independently determined by X-ray photoelectron spectroscopy (XPS). This approach is applied to NEXAFS data acquired for one of the most challenging cases: air-exposed hard carbon-based materials with adventitious carbon contamination from ambient exposure. The contribution of the adventitious carbon was removed from the as-acquired spectra of ultrananocrystalline diamond (UNCD) and hydrogenated amorphous carbon (a-C:H) to determine the intrinsic photoabsorption NEXAFS spectra of these materials. The method alters the calculated fraction of sp(2)-hybridized carbon from 5 to 20% and reveals that the adventitious contamination can be described as a layer containing carbon and oxygen ([O]/[C] = 0.11 ± 0.02) with a thickness of 0.6 ± 0.2 nm and a fraction of sp(2)-bonded carbon of 0.19 ± 0.03. This

  3. Site-selective excitation and polarized absorption and emission spectra of trivalent thulium and erbium in strontium fluorapatite

    Energy Technology Data Exchange (ETDEWEB)

    Gruber, J.B. [Department of Physics, San Jose State University, San Jose, California 95192-0106 (United States); Wright, A.O.; Seltzer, M.D. [Research and Technology Division, Naval Air Warfare Center, Code 474230D, China Lake, California 93555-6001 (United States); Zandi, B.; Merkle, L.D. [IR Optics Technology OFC, Army Research Laboratory, Ft. Belvoir, Virginia 22060-5838 (United States); Hutchinson, J.A. [Night Vision and Electronics Sensors Directorate, The United States Army, Ft. Belvoir, Virginia 22060-5806 (United States); Morrison, C.A. [Army Research Laboratory, Adelphi, Maryland 20783-1145 (United States); Allik, T.H. [Science Applications International Corporation, 1710 Goodridge Drive, McLean, Virginia 22102 (United States); Chai, B.H. [Center for Research on Electro-optics and Lasers, University of Central Florida, Orlando, Florida 32836 (United States)

    1997-05-01

    Polarized fluorescence spectra produced by site-selective excitation and conventional polarized absorption spectra were obtained for Tm{sup 3+} and Er{sup 3+} ions individually incorporated into single crystals of strontium fluorapatite, Sr{sub 5}(PO{sub 4}){sub 3}F. Substitution of the trivalent rare earth ion for divalent strontium was achieved by passive charge compensation during Czochralski growth of the fluorapatite crystals. Spectra were obtained between 1780 and 345 nm at temperatures from 4 K to room temperature on crystals having the hexagonal structure [P6{sub 3}/m(C{sub 6h}{sup 2})]. The polarized fluorescence spectra due to transitions from multiplet manifolds of Tm{sup 3+}(4f{sup 12}), including {sup 1}D{sub 2}, {sup 1}G{sub 4}, and {sup 3}H{sub 4} to manifolds {sup 3}H{sub 6} (the ground-state manifold), {sup 3}F{sub 4}, {sup 3}H{sub 5}, {sup 3}H{sub 4}, and {sup 3}F{sub 3} were analyzed for the details of the crystal-field splitting of the manifolds. Fluorescence lifetimes were measured for Tm{sup 3+} transitions from {sup 1}D{sub 2}, {sup 1}G{sub 4}, and {sup 3}H{sub 4} at room temperature and from {sup 1}G{sub 4} at 16 K. Results of the analysis indicate that the majority of Tm{sup 3+} ions occupy sites having C{sub s} symmetry. A point-charge lattice-sum calculation was made in which the crystal-field components, A{sub nm}, were determined assuming that trivalent thulium replaces divalent strontium in the metal site having C{sub s} symmetry. Results support the conclusion that the nearest-neighbor fluoride (F{sup {minus}}) is replaced by divalent oxygen (O{sup 2{minus}}), thus preserving overall charge neutrality and local symmetry. Crystal-field splitting calculations predict energy levels in agreement with experimental data. By varying the crystal-field parameters, B{sub nm}, we obtained a rms difference of 7cm{sup {minus}1} between 43 calculated and experimental Stark levels for Tm{sup 3+}(4f{sup 12}) in Tm:SFAP. (Abstract Truncated)

  4. Nitrogen K-edge X-ray absorption near edge structure (XANES) spectra of purine-containing nucleotides in aqueous solution

    International Nuclear Information System (INIS)

    Shimada, Hiroyuki; Fukao, Taishi; Minami, Hirotake; Ukai, Masatoshi; Fujii, Kentaro; Yokoya, Akinari; Fukuda, Yoshihiro; Saitoh, Yuji

    2014-01-01

    The N K-edge X-ray absorption near edge structure (XANES) spectra of the purine-containing nucleotide, guanosine 5 ′ -monophosphate (GMP), in aqueous solution are measured under various pH conditions. The spectra show characteristic peaks, which originate from resonant excitations of N 1s electrons to π* orbitals inside the guanine moiety of GMP. The relative intensities of these peaks depend on the pH values of the solution. The pH dependence is explained by the core-level shift of N atoms at specific sites caused by protonation and deprotonation. The experimental spectra are compared with theoretical spectra calculated by using density functional theory for GMP and the other purine-containing nucleotides, adenosine 5 ′ -monophosphate, and adenosine 5 ′ -triphosphate. The N K-edge XANES spectra for all of these nucleotides are classified by the numbers of N atoms with particular chemical bonding characteristics in the purine moiety

  5. X-ray absorption and infrared spectra of water and ice: A first-principles electronic structure study

    Science.gov (United States)

    Chen, Wei

    Water is of essential importance for chemistry and biology, yet the physics concerning many of its distinctive properties is not well known. In this thesis we present a theoretical study of the x-ray absorption (XA) and infrared (IR) spectra of water in liquid and solid phase. Our theoretical tools are the density functional theory (DFT), Car-Parrinello (CP) molecular dynamics (MD), and the so-called GW method. Since a systematic review of these ab initio methods is not the task of this thesis, we only briefly recall the main concepts of these methods as needed in the course of our exposition. The focus is, instead, an investigation of what is the important physics necessary for a better description of these excitation processes, in particular, core electron excitations (in XA) that reveal the local electronic structure, and vibrational excitations (in IR) associated to the molecular dynamics. The most interesting question we are trying to answer is: as we include better approximations and more complete physical descriptions of these processes, how do the aforementioned spectra reflect the underlying hydrogen-bonding network of water? The first part of this thesis consists of the first four chapters, which focus on the study of core level excitation of water and ice. The x-ray absorption spectra of water and ice are calculated with a many-body approach for electron-hole excitations. The experimental features, even the small effects of a temperature change in the liquid, are reproduced with quantitative detail using molecular configurations generated by ab initio molecular dynamics. We find that the spectral shape is controlled by two major modifications of the short range order that mark the transition from ice to water. One is associated to dynamic breaking of the hydrogen bonds which leads to a strong enhancement of the pre-edge intensity in the liquid. The other is due to densification, which follows the partial collapse of the hydrogen bond network and is

  6. Artificial intelligence applied to the automatic analysis of absorption spectra. Objective measurement of the fine structure constant

    Science.gov (United States)

    Bainbridge, Matthew B.; Webb, John K.

    2017-06-01

    A new and automated method is presented for the analysis of high-resolution absorption spectra. Three established numerical methods are unified into one `artificial intelligence' process: a genetic algorithm (Genetic Voigt Profile FIT, gvpfit); non-linear least-squares with parameter constraints (vpfit); and Bayesian model averaging (BMA). The method has broad application but here we apply it specifically to the problem of measuring the fine structure constant at high redshift. For this we need objectivity and reproducibility. gvpfit is also motivated by the importance of obtaining a large statistical sample of measurements of Δα/α. Interactive analyses are both time consuming and complex and automation makes obtaining a large sample feasible. In contrast to previous methodologies, we use BMA to derive results using a large set of models and show that this procedure is more robust than a human picking a single preferred model since BMA avoids the systematic uncertainties associated with model choice. Numerical simulations provide stringent tests of the whole process and we show using both real and simulated spectra that the unified automated fitting procedure out-performs a human interactive analysis. The method should be invaluable in the context of future instrumentation like ESPRESSO on the VLT and indeed future ELTs. We apply the method to the zabs = 1.8389 absorber towards the zem = 2.145 quasar J110325-264515. The derived constraint of Δα/α = 3.3 ± 2.9 × 10-6 is consistent with no variation and also consistent with the tentative spatial variation reported in Webb et al. and King et al.

  7. High-resolution spectra of distant compact narrow emission line galaxies: Progrenitors of spheroidal galaxies

    Science.gov (United States)

    Koo, David C.; Guzman, Rafael; Faber, S. M.; Illingworth, Garth D.; Bershady, Matthew A.; Kron, Richard G.; Takamiya, Marianne

    1995-01-01

    Emission-line velocity widths have been determined for 17 faint (B approximately 20-23) very blue, compact galaxies whose redshifts range from z = 0.095 to 0.66. The spectra have a resolution of 8 Km/s and were taken with the HIRES echelle spectrograph of the Keck 10 m telescope. The galaxies are luminous with all but two within 1 mag of M(sub B) approximately -21. Yet they exhibit narrow velocity widths between sigma = 28-157 km/s, more consistent with typical values of extreme star-forming galaxies than with those of nearby spiral galaxies of similar luminosity. In particular, objects with sigma is less than or equal to 65 km/s follow the same correlations between sigma and both blue and H beta luminosities as those of nearby H II galaxies. These results strengthen the identification of H II glaxies as thier local counterparts. The blue colors and strong emission lines suggest these compact galaxies are undergoing a recent, strong burst of star formation. Like those which characterize some H II galaxies, this burst could be a nuclear star-forming event within a much larger, older stellar population. If the burst is instead a major episode in the total star-forming history, these distant galaxies could fade enough to match the low luminosities and surface brightnesses typical of nearby spheroidals like NGC 185 or NGC 205. Together with evidence for recent star formation, exponential light profiles, and subsolar metallicities, the postfading correlations between luminosity and velocity width and bewtween luminosity and surface brightness suggest that among the low-sigma galaxies, we may be witnessing, in situ, the progenitors of today's spheroidal galaxies.

  8. THE SLOAN DIGITAL SKY SURVEY REVERBERATION MAPPING PROJECT: RAPID C iv BROAD ABSORPTION LINE VARIABILITY

    Energy Technology Data Exchange (ETDEWEB)

    Grier, C. J.; Brandt, W. N.; Trump, J. R.; Schneider, D. P. [Department of Astronomy and Astrophysics and Institute for Gravitation and the Cosmos, The Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States); Hall, P. B. [Department of Physics and Astronomy, York University, Toronto, ON M3J 1P3 (Canada); Shen, Yue [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Vivek, M.; Dawson, K. S. [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States); Ak, N. Filiz [Faculty of Sciences, Department of Astronomy and Space Sciences, Erciyes University, 38039 Kayseri (Turkey); Chen, Yuguang [Department of Astronomy, School of Physics, Peking University, Beijing 100871 (China); Denney, K. D.; Kochanek, C. S.; Peterson, B. M. [Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Green, Paul J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Jiang, Linhua [Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China); McGreer, Ian D. [Steward Observatory, The University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721-0065 (United States); Pâris, I. [INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, I-34131 Trieste (Italy); Tao, Charling [Centre de Physique des Particules de Marseille, Aix-Marseille Universite, CNRS /IN2P3, 163, avenue de Luminy, Case 902, F-13288 Marseille Cedex 09 (France); Wood-Vasey, W. M. [PITT PACC, Department of Physics and Astronomy, University of Pittsburgh, 3941 O’Hara Street, Pittsburgh, PA 15260 (United States); Bizyaev, Dmitry, E-mail: grier@psu.edu [Apache Point Observatory and New Mexico State University, P.O. Box 59, Sunspot, NM, 88349-0059 (United States); and others

    2015-06-10

    We report the discovery of rapid variations of a high-velocity C iv broad absorption line trough in the quasar SDSS J141007.74+541203.3. This object was intensively observed in 2014 as a part of the Sloan Digital Sky Survey Reverberation Mapping Project, during which 32 epochs of spectroscopy were obtained with the Baryon Oscillation Spectroscopic Survey spectrograph. We observe significant (>4σ) variability in the equivalent width (EW) of the broad (∼4000 km s{sup −1} wide) C iv trough on rest-frame timescales as short as 1.20 days (∼29 hr), the shortest broad absorption line variability timescale yet reported. The EW varied by ∼10% on these short timescales, and by about a factor of two over the duration of the campaign. We evaluate several potential causes of the variability, concluding that the most likely cause is a rapid response to changes in the incident ionizing continuum. If the outflow is at a radius where the recombination rate is higher than the ionization rate, the timescale of variability places a lower limit on the density of the absorbing gas of n{sub e} ≳ 3.9 × 10{sup 5} cm{sup −3}. The broad absorption line variability characteristics of this quasar are consistent with those observed in previous studies of quasars, indicating that such short-term variability may in fact be common and thus can be used to learn about outflow characteristics and contributions to quasar/host-galaxy feedback scenarios.

  9. Lick optical spectra of quasar HS 1946+7658 at 10 kilometers per second resolution Lyman-alpha forest and metal absorption systems

    Science.gov (United States)

    Fan, Xiao-Ming; Tytler, David

    1994-01-01

    We present optical spectra of the most luminous known quasi stellar object (QSO) HS 1946+7658 (z(sub em) = 3.051). Our spectra have both full wavelength coverage, 3240-10570 A, and in selected regions, either high signal-to-noise ratio, SNR approximately equals 40-100, or unusually high approximately 10 km/sec resolution, and in parts of the Ly alpha forest and to the red of Ly alpha emission they are among the best published. We find 113 Ly alpha systems and six metal-line systems, three of which are new. The metal systems at z(sub abs) = 2.844 and 3.050 have complex velocity structure with four and three prominent components, respectively. We find that the system at z(sub abs) = 2.844 is a damped Ly alpha absorption (DLA) system, with a neutral hydrogen column density of log N(H I) = 20.2 +/- 0.4, and it is the cause of the Lyman limit break at lambda approximately equals 3520 A. We believe that most of the H I column density in this system is in z(sub abs) = 2.8443 component which shows the strongest low-ionization absorption lines. The metal abundance in the gas phase of the system is (M/H) approximately equals -2.6 +/- 0.3, with a best estimate of (M/H) = -2.8, with ionizaion parameter log gamma = -2.75, from a photoionization model. The ratios of the logarithmic abundances of C, O, Al, and Si are all within a factor of 2 of solar, which is important for two reasons. First, we believe that the gas abundances which we measure are close to the total abundances, because the ratio of aluminum to other elements is near cosmic, and Al is a refractory element which depletes very readily like chromium, in the interstellar medium. Second, we do not see the enhancement of O with respect to C of (O/C) approximately equals 0.5-0.9 reported in three partial Lyman limit systems by Reimers et al. (1992) and Vogel & Reimers (1993); we measure (O/C) = -0.06 for observed ions and (O/C) approximately equals 0.2 after ionization corrections, which is consistent with solar

  10. Package for Interactive Analysis of Line Emission (Analysis of UV-X-Ray High-Resolution Emission Spectra)

    Science.gov (United States)

    Hunter, Paul (Technical Monitor); Kashyap, Vinay

    2004-01-01

    The Package for Interactive Analysis of Line Emission (PINTofALE) is a suite of IDL routines designed to carry out spectroscopic analysis of high-resolution X-ray spectra. The current version is 1.5, and will shortly be upgraded to v2. A detailed description of the package, together with detailed documentation, example walk-throughs, science threads, and downloadable tar files, are available on-line.

  11. Integrative fitting of absorption line profiles with high accuracy, robustness, and speed

    Science.gov (United States)

    Skrotzki, Julian; Habig, Jan Christoph; Ebert, Volker

    2014-08-01

    The principle of the integrative evaluation of absorption line profiles relies on the numeric integration of absorption line signals to retrieve absorber concentrations, e.g., of trace gases. Thus, it is a fast and robust technique. However, previous implementations of the integrative evaluation principle showed shortcomings in terms of accuracy and the lack of a fit quality indicator. This has motivated the development of an advanced integrative (AI) fitting algorithm. The AI fitting algorithm retains the advantages of previous integrative implementations—robustness and speed—and is able to achieve high accuracy by introduction of a novel iterative fitting process. A comparison of the AI fitting algorithm with the widely used Levenberg-Marquardt (LM) fitting algorithm indicates that the AI algorithm has advantages in terms of robustness due to its independence from appropriately chosen start values for the initialization of the fitting process. In addition, the AI fitting algorithm shows speed advantages typically resulting in a factor of three to four shorter computational times on a standard personal computer. The LM algorithm on the other hand retains advantages in terms of a much higher flexibility, as the AI fitting algorithm is restricted to the evaluation of single absorption lines with precomputed line width. Comparing both fitting algorithms for the specific application of in situ laser hygrometry at 1,370 nm using direct tunable diode laser absorption spectroscopy (TDLAS) suggests that the accuracy of the AI algorithm is equivalent to that of the LM algorithm. For example, a signal-to-noise ratio of 80 and better typically yields a deviation of cloud chamber aerosol interactions and dynamics in the atmosphere (AIDA)—a unique large-scale facility to study atmospheric processes. The robustness of the AI fitting algorithm has been validated for typical AIDA conditions encompassing strong transmission fluctuations during the formation of droplet or ice

  12. Chirped pulse generation of a narrow absorption line in a Tm 3+:YAG crystal

    Science.gov (United States)

    de Sèze, F.; Lavielle, V.; Lorgeré, I.; Le Gouët, J.-L.

    2003-08-01

    We examine the coherent aspects of the swept CW laser spectral hole burning procedure, exploring their connection with rapid adiabatic passage (RAP). We take advantage of the well-known RAP robustness against control parameter variations. Considering uniform excitation of all the absorbing centers over a given spectral range, we propose a new scheme to exclude a single-frequency subset of centers from excitation. As the excited centers decay to a shelving state, one is left with nothing but the subset of unexcited centers that will behave like a narrow absorption line sample. Preliminary experimental results are presented.

  13. Accurate determination of low state rotational quantum numbers (J < 4) from planar-jet and liquid nitrogen cell absorption spectra of methane near 1.4 micron

    Czech Academy of Sciences Publication Activity Database

    Votava, Ondřej; Mašát, M.; Pracna, Petr; Kassi, S.

    2010-01-01

    Roč. 12, č. 13 (2010), s. 3145-3155 ISSN 1463-9076 R&D Projects: GA AV ČR IAA400400706 Institutional research plan: CEZ:AV0Z40400503 Keywords : spectroscopy * absorption spectra * physical chemistry Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.454, year: 2010

  14. Phase-dependent absorption features in X-ray spectra of X-ray Dim Isolated Neutron Stars

    Science.gov (United States)

    Borghese, A.; Rea, N.; Coti Zelati, F.; Turolla, R.; Tiengo, A.; Zane, S.

    2017-12-01

    A detailed phase-resolved spectroscopy of archival XMM–Newton observations of X-ray Dim Isolated Neutron Stars (XDINSs) led to the discovery of narrow and strongly phase-dependent absorption features in two of these sources. The first was discovered in the X-ray spectrum of RX J0720.4-3125, followed by a new possible candidate in RX J1308.6+2127. Both spectral lines have similar properties: they are detected for only ∼ 20% of the rotational cycle and appear to be stable over the timespan covered by the observations. We performed Monte Carlo simulations to test the significance of these phase-variable features and in both cases the outcome has confirmed the detection with a confidence level > 4.6σ. Because of the narrow width and the strong dependence on the pulsar rotational phase, the most likely interpretation for these spectral features is in terms of resonant proton cyclotron absorption scattering in a confined high-B structure close to the stellar surface. Within the framework of this interpretation, our results provide evidence for deviations from a pure dipole magnetic field on small scales for highly magnetized neutron stars and support the proposed scenario of XDINSs being aged magnetars, with a strong non-dipolar crustal B-field component.

  15. TD-M06-2X insights into the absorption and emission spectra of dichlorvos and its molecularly imprinted recognition by methacrylic acid.

    Science.gov (United States)

    Cheng, Xueli

    2016-11-01

    The absorption and emission spectra of dichlorvos and the dichlorvos-MAA complex in methanol, water, and chloroform in the molecularly imprinted recognition were investigated systematically. The M06-2X results revealed that: 1) the hydroxyl groups in polar solvents such as methanol and water may markedly influence the weak interactions, and then alter the adsorption and emission spectra; 2) the electronic excitation in absorption spectra of dichlorvos is dominated by the configuration HOMO → LUMO, but in the most stable dichlorvos-MAA it becomes the ππ* excitation of HOMO → LUMO + 1; 3) Mulliken charges reveal that dichlorvos almost dissociates to Cl - and a cation in its S 1 excitation state; 4) the phosphorescence spectra of dichlorvos-MAA are relatively weak. Graphical Abstract The absorption and emission spectra of dichlorvos and the dichlorvos-MAA complex in the molecularly imprinted recognition of dichlorvos were investigated systematically in methanol, water, and chloroform as solvents.

  16. AN STIS ATLAS OF Ca II TRIPLET ABSORPTION LINE KINEMATICS IN GALACTIC NUCLEI

    International Nuclear Information System (INIS)

    Batcheldor, D.; Mandalou, J.; Axon, D.; Valluri, M.; Merritt, D.

    2013-01-01

    The relations observed between supermassive black holes and their host galaxies suggest a fundamental link in the processes that cause these two objects to evolve. A more comprehensive understanding of these relations could be gained by increasing the number of supermassive black hole mass (M . ) measurements. This can be achieved, in part, by continuing to model the stellar dynamics at the centers of galactic bulges using data of the highest possible spatial resolution. Consequently, we present here an atlas of galaxies in the Space Telescope Imaging Spectrograph (STIS) data archive that may have spectra suitable for new M . estimates. Archived STIS G750M data for all non-barred galactic bulges are co-aligned and combined, where appropriate, and the radial signal-to-noise ratios calculated. The line-of-sight velocity distributions from the Ca II triplet are then determined using a maximum penalized likelihood method. We find 19 out of 42 galaxies may provide useful new M . estimates since they are found to have data that is comparable in quality with data that has been used in the past to estimate M . . However, we find no relation between the signal-to-noise ratio in the previously analyzed spectra and the uncertainties of the black hole masses derived from the spectra. We also find that there is a very limited number of appropriately observed stellar templates in the archive from which to estimate the effects of template mismatching

  17. The Stellar Initial Mass Function in Early-type Galaxies from Absorption Line Spectroscopy. I. Data and Empirical Trends

    Science.gov (United States)

    van Dokkum, Pieter G.; Conroy, Charlie

    2012-11-01

    The strength of gravity-sensitive absorption lines in the integrated light of old stellar populations is one of the few direct probes of the stellar initial mass function (IMF) outside of the Milky Way. Owing to the advent of fully depleted CCDs with little or no fringing it has recently become possible to obtain accurate measurements of these features. Here, we present spectra covering the wavelength ranges 0.35-0.55 μm and 0.72-1.03 μm for the bulge of M31 and 34 early-type galaxies from the SAURON sample, obtained with the Low Resolution Imaging Spectrometer on Keck. The signal-to-noise ratio is >~ 200 Å-1 out to 1 μm, which is sufficient to measure gravity-sensitive features for individual galaxies and to determine how they depend on other properties of the galaxies. Combining the new data with previously obtained spectra for globular clusters in M31 and the most massive elliptical galaxies in the Virgo cluster, we find that the dwarf-sensitive Na I λ8183, 8195 doublet and the FeH λ9916 Wing-Ford band increase systematically with velocity dispersion, while the giant-sensitive Ca II λ8498, 8542, 8662 triplet decreases with dispersion. These trends are consistent with a varying IMF, such that galaxies with deeper potential wells have more dwarf-enriched mass functions. In a companion paper, we use a comprehensive stellar population synthesis model to demonstrate that IMF effects can be separated from age and abundance variations and quantify the IMF variation among early-type galaxies.

  18. THE STELLAR INITIAL MASS FUNCTION IN EARLY-TYPE GALAXIES FROM ABSORPTION LINE SPECTROSCOPY. I. DATA AND EMPIRICAL TRENDS

    International Nuclear Information System (INIS)

    Van Dokkum, Pieter G.; Conroy, Charlie

    2012-01-01

    The strength of gravity-sensitive absorption lines in the integrated light of old stellar populations is one of the few direct probes of the stellar initial mass function (IMF) outside of the Milky Way. Owing to the advent of fully depleted CCDs with little or no fringing it has recently become possible to obtain accurate measurements of these features. Here, we present spectra covering the wavelength ranges 0.35-0.55 μm and 0.72-1.03 μm for the bulge of M31 and 34 early-type galaxies from the SAURON sample, obtained with the Low Resolution Imaging Spectrometer on Keck. The signal-to-noise ratio is ∼> 200 Å –1 out to 1 μm, which is sufficient to measure gravity-sensitive features for individual galaxies and to determine how they depend on other properties of the galaxies. Combining the new data with previously obtained spectra for globular clusters in M31 and the most massive elliptical galaxies in the Virgo cluster, we find that the dwarf-sensitive Na I λ8183, 8195 doublet and the FeH λ9916 Wing-Ford band increase systematically with velocity dispersion, while the giant-sensitive Ca II λ8498, 8542, 8662 triplet decreases with dispersion. These trends are consistent with a varying IMF, such that galaxies with deeper potential wells have more dwarf-enriched mass functions. In a companion paper, we use a comprehensive stellar population synthesis model to demonstrate that IMF effects can be separated from age and abundance variations and quantify the IMF variation among early-type galaxies.

  19. On-line determination of manganese in solid seafood samples by flame atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Yebra, M.C.; Moreno-Cid, A.

    2003-01-01

    Manganese is extracted on-line from solid seafood samples by a simple continuous ultrasound-assisted extraction system (CUES). This system is connected to an on-line manifold, which permits the flow-injection flame atomic absorption spectrometric determination of manganese. Optimisation of the continuous leaching procedure is performed by an experimental design. The proposed method allows the determination of manganese with a relative standard deviation of 0.9% for a sample containing 23.4 μg g -1 manganese (dry mass). The detection limit is 0.4 μg g -1 (dry mass) for 30 mg of sample and the sample throughput is ca. 60 samples per hour. Accurate results are obtained by measuring TORT-1 certified reference material. The procedure is finally applied to mussel, tuna, sardine and clams samples

  20. Absorption spectra and cyclic voltammograms of uranium species in molten lithium molybdate-sodium molybdate eutectic at 550 C

    International Nuclear Information System (INIS)

    Nagai, T.; Fukushima, M.; Myochin, M.; Uehara, A.; Fujii, T.; Yamana, H.; Sato, N.

    2011-01-01

    Absorption spectra of uranium species dissolved in molten lithium molybdate.sodium molybdate eutectic of 0.51Li 2 MoO 4 -0.49Na 2 MoO 4 mixture at 550 C were measured by UV/Vis/NIR spectrophotometry, and their redox reactions were investigated by cyclic voltammetry. We found that the major ions of uranium species dissolved in the melt were uranyl penta-valent. After purging dry oxygen gas into the melt, pentavalent species were oxidized to the uranyl hexa-valent. In the cyclic voltammetry of the melt without uranium species, it was confirmed that the lithium-sodium molybdenum oxide compounds were deposited on the working electrode at the negative potential and the lithium molybdenum oxide compounds were deposited on the counter electrode at positive potential. When UO 2 was dissolved into the melt, the reductive reaction of the uranium species was observed at the reductive potential of the pure melt. This suggests that the uranium species dissolved in the melts could be recovered as mixed uranium-molybdenum oxides by electrolysis. (orig.)

  1. Proposal for an experiment at the SIN: contribution on πE3-beam dosimetry. Measurement of particle spectra after pion absorption in biologically interesting nuclei

    International Nuclear Information System (INIS)

    Appel, H.; Boehmer, V.; Bueche, G.; Kluge, W.; Matthay, H.

    It is proposed to measure the energy spectra of light charged particles (protons, deuterons, tritons, 3 He- and 4 He-nuclei) and of neutrons, after the absorption of stopped pions in the biologically interesting hydrogen, oxygen, carbon, and nitrogen nuclei. In addition, the relative particle yield will be examined in tissue-like targets such as polyethylene, plexiglas, and water. Furthermore, it is proposed to measure the coincidence spectra of two particles emitted after absorption, as a function of the angle between their impulses. In the case of a pure three-body decay, these examinations may open the possibility of drawing conclusions about the heavy recoil nuclei arising during pion absorption. Particle energy and type will be determined by a combined time-of-flight/energy measurement with totally absorbent NaI or plastic detectors. The HF signal will serve as a start signal for time-of-flight measurements

  2. What's in the Wind? Determining the Properties of Outflowing Gas in Powerful Broad Absorption Line Quasars

    Science.gov (United States)

    Leighly, Karen

    2017-08-01

    A significant fraction of quasars exhibits blueshifted broadabsorption lines (BALs) in their rest-UV spectra, indicating powerfuloutflows emerging from the central engine. These outflows may removeangular momentum to enable black hole growth, enrich the intergalacticmedium with metals, and trigger quenching of star formation ingalaxies. Despite years of study, the physical conditions of theoutflowing gas are poorly understood. The handful of objects that havebeen subjected to detailed analysis are atypical and characterized byrelatively narrow lines where blending is unimportant. However,investigating more powerful BAL quasars will give us better insightinto the types of outflows much more likely to impact galaxyevolution.SimBAL is a novel spectral synthesis fitting method for BAL quasarsthat uses Bayesian model calibration to compare synthetic to observedspectra. With the model inputs of ionization parameter, columndensity, and covering fraction specified, the gas properties givingrise to the BAL features can be determined. We propose to applySimBAL to archival spectra of a sample of 14 luminous BAL quasars to characterize their bulk outflow properties as a function of velocityfor the first time. Our results will show the range of parameterstypical of powerful outflows, an essential step towards constrainingthe physics behind quasar winds and thus their impact on theirenvironments.

  3. Shaping the spectra of the line-to-line voltage using signal injection in the common mode voltage

    DEFF Research Database (Denmark)

    Mathe, Laszlo; Rasmussen, Peter Omand; Pedersen, John Kim

    2009-01-01

    A drawback of Pulse Width Modulation in electrical drives is the high harmonic content of the line to line voltages, which gives rise to Electro-Magnetic Interference and acoustic noise. By injection of a signal into the common mode voltage, the fundamental is not affected, but new frequency...... components are introduced in the line to line voltage spectrum. This paper introduces a new analytical method for estimation of the line to line voltage spectrum, where sinusoidal signal is injected into the common mode voltage. Based on the analytical calculations, also a new fixed carrier frequency quasi...

  4. Crowdsourcing Broad Absorption Line Properties and Other Features of Quasar Outflow Using Zooniverse Citizen Science Project Platform

    Science.gov (United States)

    Crowe, Cassie; Lundgren, Britt; Grier, Catherine

    2018-01-01

    The Sloan Digital Sky Survey (SDSS) regularly publishes vast catalogs of quasars and other astronomical objects. Previously, the SDSS collaboration has used visual inspection to check quasar redshift validity and flag instances of broad absorption lines (BALs). This information helps researchers to easily single out the quasars with BAL properties and study their outflows and other intervening gas clouds. Due to the ever-growing number of new SDSS quasar observations, visual inspections are no longer possible using previous methods. Currently, BAL information is being determined entirely computationally, and the accuracy of that information is not precisely known. This project uses the Zooniverse citizen science platform to visually inspect quasar spectra for BAL properties, to check the accuracy of the current autonomous methods, and to flag multi-phase outflows and find candidates for in-falling gas into the quasar central engine. The layout and format of a Zooniverse project provides an easier way to inspect and record data on each spectrum and share the workload via crowdsourcing. Work done by the SDSS collaboration members is serving as a beta test for a public project upon the official release of the DR14 quasar catalog by SDSS.

  5. XMM-Newton Spectroscopy of the X-ray Detected Broad Absorption Line QSO CSO 755

    Science.gov (United States)

    Brandt, Niel

    2005-01-01

    We present the results from XMM-Newton observations of the highly optically polarized broad absorption line quasar (BALQSO) CSO 755. By analyzing its X-ray spectrum with a total of approximately 3000 photons we find that this source has an X-ray continuum of "typical" radio-quiet quasars, with a photon index of Gamma=1.83, and a rather flat (X-ray bright) intrinsic optical-to-X-ray spectral slope of alpha_ox=- 1.51. The source shows evidence for intrinsic absorption, and fitting the spectrum with a neutral-absorption model gives a column density of N_H approximately 1.2x10^22 cm^{-2}; this is among the lowest X-ray columns measured for BALQSOs. We do not detect, with high significance, any other absorption features in the X-ray spectrum. Upper limits we place on the rest-frame equivalent width of a neutral (ionized) Fe K-alpha line, less than =180 eV (less than =120 eV), and on the Compton-reflection component parameter, R less than =0.2, suggest that most of the X-rays from the source are directly observed rather than being scattered or reflected; this is also supported by the relatively flat intrinsic alpha ox we measure. The possibility that most of the X-ray flux is scattered due to the high level of UV-optical polarization is ruled out. Considering data for 46 BALQSOs from the literature, including CSO 755, we have found that the UV-optical continuum polarization level of BALQSOs is not correlated with any of their X-ray properties. A lack of significant short-term and long-term X-ray flux variations in the source may be attributed to a large black-hole mass in CSO 755. We note that another luminous BALQSO, PG 2112+059, has both similar shallow C IV BALs and moderate X-ray absorption.

  6. Water-vapor absorption line measurements in the 940-nm band by using a Raman-shifted dye laser

    Science.gov (United States)

    Chu, Zhiping; Wilkerson, Thomas D.; Singh, Upendra N.

    1993-01-01

    We report water-vapor absorption line measurements that are made by using the first Stokes radiation (930-982 nm) with HWHM 0.015/cm generated by a narrow-linewidth, tunable dye laser. Forty-five absorption line strengths are measured with an uncertainty of 6 percent and among them are fourteen strong lines that are compared with previous measurements for the assessment of spectral purity of the light source. Thirty air-broadened linewidths are measured with 8 percent uncertainty at ambient atmospheric pressure with an average of 0.101/cm. The lines are selected for the purpose of temperature-sensitive or temperature-insensitive lidar measurements. Results for these line strengths and linewidths are corrected for broadband radiation and finite laser linewidth broadening effects and compared with the high-resolution transmission molecular absorption.

  7. A comparative study of EL2 and other deep centers in undoped SI GaAs using optical absorption spectra and photoconductivity measurements

    Energy Technology Data Exchange (ETDEWEB)

    Kozlova, J.P. E-mail: jpkozlova@rbcmail.ru; Bowles, T.J.; Eremin, V.K.; Gavrin, V.N.; Koshelev, O.G.; Markov, A.V.; Morozova, V.A.; Polyakov, A.J.; Verbitskaya, E.M.; Veretenkin, E.P

    2003-10-11

    The performance of radiation detectors fabricated from semi-insulating (SI) GaAs is highly sensitive to EL2{sup +}-concentration in the material. Near-infrared optical absorption measurements are commonly used to determine the EL2-concentration and to roughly estimate the EL2{sup +}-concentration under the assumption that the optical absorption is mainly determined by the photoionization and the photoneutralization of EL2{sup 0} and EL2{sup +}, respectively. However, the presence of different native defects can contribute to optical absorption and reduce the precision of determination of EL2-concentration. In this work, we evaluate the contributions into optical absorption from EL2 and other deep center namely EL3 defect (0.55 eV) using near-infrared optical absorption and photoconductivity (PC) measurements in the photon energy interval 0.5-1.4 eV for SI GaAs crystals grown by the liquid encapsulated Czochralski method from melts with As content changing from 50% to about 46%. The photoelectrical spectra were measured on p-i-n structure detectors with heavily doped p{sup +} and n{sup +} layers grown by Liquid Phase Epitaxy and on Schottky diodes. The short circuit photocurrent spectra were registered for all detectors in the energy interval 0.65-1.4 eV. Unexpectedly, the current sensitivities in the regions of the extrinsic and intrinsic absorption were comparable. A comparative study of optical absorption, PC and short circuit photocurrent spectra resulted in determination of EL2{sup +}-concentration. It was concluded that contribution of additional deep centers, particularly the ionized EL3{sup +} defect could be comparable to the EL2-contribution. The EL3 centers were attributed to oxygen-related defects based on published results and on some indirect evidence in our experimental data.

  8. Computer simulation of ICP spectra: A new tool for the study of excitation, emission, and line overlap

    International Nuclear Information System (INIS)

    Blades, M.W.; Burton, L.L.

    1986-01-01

    It is well known that the relatively high temperature of ICP sources provides an excitation environment relatively free from dissociation and vaporization interferences and, in addition, produces intense analyte line spectra and hence high analytical sensitivity. However, this feature also introduces the potential for spectral overlaps from sample concomitants. The degree to which an analyte spectral line intensity can be corrected for interfering spectral overlaps depends on many factors including spectrometer resolution, sample composition and ICP operating conditions. The authors have been using a computer program to assist them in the study of ICP analyte emission spectra. This program is being used to study the spectral distribution of line intensity information and also to do detailed investigations on spectral overlaps in complex sample mixtures. As input data the program uses tabulated wavelengths, transition probabilities (gA values), partition functions, excitation energies of the transitions, ionization energy, temperature, and Doppler and Stark linewidths

  9. Evidence for ultra-fast outflows in radio-quiet AGNs. I. Detection and statistical incidence of Fe K-shell absorption lines

    Science.gov (United States)

    Tombesi, F.; Cappi, M.; Reeves, J. N.; Palumbo, G. G. C.; Yaqoob, T.; Braito, V.; Dadina, M.

    2010-10-01

    Context. Blue-shifted Fe K absorption lines have been detected in recent years between 7 and 10 keV in the X-ray spectra of several radio-quiet AGNs. The derived blue-shifted velocities of the lines can often reach mildly relativistic values, up to 0.2-0.4c. These findings are important because they suggest the presence of a previously unknown massive and highly ionized absorbing material outflowing from their nuclei, possibly connected with accretion disk winds/outflows. Aims: The scope of the present work is to statistically quantify the parameters and incidence of the blue-shifted Fe K absorption lines through a uniform analysis on a large sample of radio-quiet AGNs. This allows us to assess their global detection significance and to overcome any possible publication bias. Methods: We performed a blind search for narrow absorption features at energies greater than 6.4 keV in a sample of 42 radio-quiet AGNs observed with XMM-Newton. A simple uniform model composed by an absorbed power-law plus Gaussian emission and absorption lines provided a good fit for all the data sets. We derived the absorption lines parameters and calculated their detailed detection significance making use of the classical F-test and extensive Monte Carlo simulations. Results: We detect 36 narrow absorption lines on a total of 101 XMM-Newton EPIC pn observations. The number of absorption lines at rest-frame energies higher than 7 keV is 22. Their global probability to be generated by random fluctuations is very low, less than 3 × 10-8, and their detection have been independently confirmed by a spectral analysis of the MOS data, with associated random probability UFOs) those highly ionized absorbers with outflow velocities higher than 104 km s-1, then the majority of the lines are consistent with being associated to UFOs and the fraction of objects with detected UFOs in the whole sample is at least ~35%. This fraction is similar for type 1 and type 2 sources. The global covering fraction of

  10. Upper limits on metals in quasar Lyman-alpha forest clouds: Absence of C 5 lines in echelle spectra

    Science.gov (United States)

    Tytler, David; Fan, Xiao-Ming

    1994-01-01

    Recently Lu presented tentative evidence for C IV lines in Quasi-Stellar Object (QSO) Ly-alpha forest systems with strong lines. We have performed a similar search for C IV in our 10 km/s resolution echelle spectra of the bright QSO HS 1946+7658. We shifted the spectra to align the expected positions of the C IV lines in 65 Ly-alpha systems and then added them. The resulting composite spectrum, equivalent to 390 hr of exposure time on the Lick 3 m telescope, has a signal-to-noise ratio of 80 per 0.025 A in the rest frame of the absorbers. We do not see any C IV lines down to a 2 sigma limit of W(1548) less than or equal to 1.4 mA, about one fifth of the strength of the lines seen by Lu. The C IV lines that Lu saw must be restricted to rare Ly-alpha systems with large H I column densities greater than or equal to 10(exp 14)/sq cm, which are too rare to show C IV in our sample. More common Ly-alpha systems with H I column densities of 10(exp 13)-10(exp 14)/sq cm do not show C IV lines. If their ionization is H/H I = 10(exp 4) then they have (C/H) less than or equal to -2.0.

  11. The SAURON project : XVII. Stellar population analysis of the absorption line strength maps of 48 early-type galaxies

    NARCIS (Netherlands)

    Kuntschner, Harald; Emsellem, Eric; Bacon, Roland; Cappellari, Michele; Davies, Roger L.; de Zeeuw, P. Tim; Falcon-Barroso, Jesus; Krajnovic, Davor; McDermid, Richard M.; Peletier, Reynier F.; Sarzi, Marc; Shapiro, Kristen L.; van den Bosch, Remco C. E.; van de Ven, Glenn; Krajnović, Davor

    2010-01-01

    We present a stellar population analysis of the absorption line strength maps for 48 early-type galaxies from the SAURON sample. Using the line strength index maps of H beta, Fe5015 and Mgb, measured in the Lick/IDS system and spatially binned to a constant signal-to-noise ratio, together with

  12. The SAURON project - XVII. Stellar population analysis of the absorption line strength maps of 48 early-type galaxies

    NARCIS (Netherlands)

    Kuntschner, Harald; Emsellem, Eric; Bacon, Roland; Cappellari, Michele; Davies, Roger L.; de Zeeuw, P. Tim; Falcón-Barroso, Jesús; Krajnović, Davor; McDermid, Richard M.; Peletier, Reynier F.; Sarzi, Marc; Shapiro, Kristen L.; van den Bosch, Remco C. E.; van de Ven, Glenn

    2010-01-01

    We present a stellar population analysis of the absorption line strength maps for 48 early-type galaxies from the SAURON sample. Using the line strength index maps of Hβ, Fe5015 and Mgb, measured in the Lick/IDS system and spatially binned to a constant signal-to-noise ratio, together with

  13. VACTIV: A graphical dialog based program for an automatic processing of line and band spectra

    Science.gov (United States)

    Zlokazov, V. B.

    2013-05-01

    The program VACTIV-Visual ACTIV-has been developed for an automatic analysis of spectrum-like distributions, in particular gamma-ray spectra or alpha-spectra and is a standard graphical dialog based Windows XX application, driven by a menu, mouse and keyboard. On the one hand, it was a conversion of an existing Fortran program ACTIV [1] to the DELPHI language; on the other hand, it is a transformation of the sequential syntax of Fortran programming to a new object-oriented style, based on the organization of event interactions. New features implemented in the algorithms of both the versions consisted in the following as peak model both an analytical function and a graphical curve could be used; the peak search algorithm was able to recognize not only Gauss peaks but also peaks with an irregular form; both narrow peaks (2-4 channels) and broad ones (50-100 channels); the regularization technique in the fitting guaranteed a stable solution in the most complicated cases of strongly overlapping or weak peaks. The graphical dialog interface of VACTIV is much more convenient than the batch mode of ACTIV. [1] V.B. Zlokazov, Computer Physics Communications, 28 (1982) 27-37. NEW VERSION PROGRAM SUMMARYProgram Title: VACTIV Catalogue identifier: ABAC_v2_0 Licensing provisions: no Programming language: DELPHI 5-7 Pascal. Computer: IBM PC series. Operating system: Windows XX. RAM: 1 MB Keywords: Nuclear physics, spectrum decomposition, least squares analysis, graphical dialog, object-oriented programming. Classification: 17.6. Catalogue identifier of previous version: ABAC_v1_0 Journal reference of previous version: Comput. Phys. Commun. 28 (1982) 27 Does the new version supersede the previous version?: Yes. Nature of problem: Program VACTIV is intended for precise analysis of arbitrary spectrum-like distributions, e.g. gamma-ray and X-ray spectra and allows the user to carry out the full cycle of automatic processing of such spectra, i.e. calibration, automatic peak search

  14. The velocity distribution of interstellar gas observed in strong UV absorption lines

    Science.gov (United States)

    Cowie, L. L.; York, D. G.

    1978-01-01

    Observations of three strong interstellar UV absorption lines of N I (1199 A), N II (1083 A), and Si III (1206 A) in 47 stars of widely varying distance and a variety of spectral types are analyzed to obtain a velocity distribution function for the interstellar gas. A technique based on the maximum and minimum velocities observed along a line of sight is adopted because of heavy line blending, and results are discussed for both power-law and exponential distribution functions. The expected distribution of radiative-phase supernova remnants (SNRs) in the interstellar medium is calculated as a function of SNR birthrate and of the interstellar density in which they evolve. The results are combined with observed distance estimates, and it is shown that an interstellar density in excess of 0.1 per cu cm would be required to keep the SNRs sufficiently confined so that their cross sections are consistent with the observed number of components. The alternative possibility is considered that SNRs do not enter the radiative phase before escaping from the Galaxy or colliding with neighboring remnants.

  15. Dataset of the absorption, emission and excitation spectra and fluorescence intensity graphs of fluorescent cyanine dyes for the quantification of low amounts of dsDNA.

    Science.gov (United States)

    Bruijns, Brigitte; Tiggelaar, Roald; Gardeniers, Han

    2017-02-01

    This article describes data related to a research article entitled "Fluorescent cyanine dyes for the quantification of low amounts of dsDNA" (B. Bruijns, R. Tiggelaar, J. Gardeniers, 2016) [1]. Six cyanine dsDNA dyes - EvaGreen, SYBR Green, PicoGreen, AccuClear, AccuBlue NextGen and YOYO-1 - are investigated and in this article the absorption spectra, as well as excitation and emission spectra, for all six researched cyanine dyes are given, all recorded under exactly identical experimental conditions. The intensity graphs, with the relative fluorescence in the presence of low amounts of dsDNA, are also provided.

  16. Structures, vibrational absorption and vibrational circular dichroism spectra of L-alanine in aqueous solution: a density functional theory and RHF study

    DEFF Research Database (Denmark)

    Frimand, Kenneth; Bohr, Henrik; Jalkanen, Karl J.

    2000-01-01

    A detailed comparative study of structures, vibrational absorption (VA) and vibrational circular dichroism (VCD) spectra has been carried out for the zwitterionic structure of the amino acid L-alanine. Theoretically determined structures necessary for deriving VA and VCD spectra were calculated...... at the density functional theory level using the B3LYP functional with the 6-31G* basis set. The Hessians and atomic polar tensors and atomic axial tensors were all calculated at the B3LYP/6-31G* level of theory. An important result is the method of treating solvent effects by both adding explicit water...

  17. Primary orbit and the absorption lines of HDE 226868 (Cygnus X-1)

    International Nuclear Information System (INIS)

    Ninkov, Z.; Walker, G.A.H.; Yang, S.

    1987-01-01

    From Reticon spectra of about 1 A resolution taken between 1980 and 1984, the radial velocity curve of HDE 226868 is found to be characteristic of a single-line spectroscopic binary with K = 75.0 + or - 1.0 km/s and e = 0.0. Combining historical velocities from the literature with present data and applying a period-folding analysis, a period of 5.59964 + or - 0.00001 days is found. These values agree well with those published by Gies and Bolton (1982). The value of v sin i is estimated to be 94.3 + or - 5 km/s from CFHT Reticon spectra taken at 0.1 A resolution. Assuming that the rotation of the primary is synchronized to the orbital revolution of the secondary gives a primary to secondary mass ratio between 1.5 and 2.3. An absolute magnitude of -6.5 + or - 0.2 is derived from the equivalent width of H-gamma (1.5 + or - 0.1 A) and the calibration of Walker and Millward (1985), which is consistent with the spectral classification of O9.7 Iab. Assuming 20 solar masses as a reasonable estimate for the mass of the primary implies a mass of 10 + or - 1 solar masses for the secondary. 62 references

  18. UV-VIS Absorption Spectra of Molten AgCl and AgBr and of their Mixtures with Group I and II Halide Salts

    Science.gov (United States)

    Greening, Giorgio G. W.

    2015-10-01

    The UV-VIS absorption spectra of (Ag1-X[Li-Cs, Ba]X)Cl and of (Ag1-X[Na, K, Cs]X)Br at 823 K at the concentrations X=0.0, 0.1, 0.2 have been measured. The findings show that on adding the respective halides to molten silver chloride and silver bromide, shifts of the fundamental absorption edge to shorter wavelengths result. A correlation between the observed shifts and the expansion of the silver sub-lattice is found, which is valid for both silver halide systems studied in this work.

  19. Time-Resolved Absorption and Resonance Raman Spectra of the lowest Excited Triplet State of All-Trans-1,3,5-Heptatriene

    DEFF Research Database (Denmark)

    Langkilde, Frans; Wilbrandt, Robert Walter; Jensen, Niels-Henrik

    1984-01-01

    The lowest excited triplet state of all-trans-1,3,5-heptatriene has been studied by time-resolved absorption and resonance Raman spectroscopy. The difference absorption spectrum of the triplet state has a maximum around 315 nm, and the triplet state decays by first-order kinetics with k = (3.4 ± 0.......3) × 106 s−1. Time-resolved resonance Raman spectra of the heptatriene triplet excited at 317.5 nm showed bands at 1574, 1298, 1275, 1252, 1209, and 1132 cm−1....

  20. Accurate Theoretical Methane Line Lists in the Infrared up to 3000 K and Quasi-continuum Absorption/Emission Modeling for Astrophysical Applications

    Science.gov (United States)

    Rey, Michael; Nikitin, Andrei V.; Tyuterev, Vladimir G.

    2017-10-01

    Modeling atmospheres of hot exoplanets and brown dwarfs requires high-T databases that include methane as the major hydrocarbon. We report a complete theoretical line list of 12CH4 in the infrared range 0-13,400 cm-1 up to T max = 3000 K computed via a full quantum-mechanical method from ab initio potential energy and dipole moment surfaces. Over 150 billion transitions were generated with the lower rovibrational energy cutoff 33,000 cm-1 and intensity cutoff down to 10-33 cm/molecule to ensure convergent opacity predictions. Empirical corrections for 3.7 million of the strongest transitions permitted line position accuracies of 0.001-0.01 cm-1. Full data are partitioned into two sets. “Light lists” contain strong and medium transitions necessary for an accurate description of sharp features in absorption/emission spectra. For a fast and efficient modeling of quasi-continuum cross sections, billions of tiny lines are compressed in “super-line” libraries according to Rey et al. These combined data will be freely accessible via the TheoReTS information system (http://theorets.univ-reims.fr, http://theorets.tsu.ru), which provides a user-friendly interface for simulations of absorption coefficients, cross-sectional transmittance, and radiance. Comparisons with cold, room, and high-T experimental data show that the data reported here represent the first global theoretical methane lists suitable for high-resolution astrophysical applications.

  1. Metal Absorption Lines as Probes of the Intergalactic Medium Prior to the Reionization Epoch

    Science.gov (United States)

    Furlanetto, Steven R.; Loeb, Abraham

    2003-05-01

    Winds from star-forming galaxies provide the most promising explanation for the enrichment of the intergalactic medium with heavy elements. Theoretical and observational arguments indicate that the pollution may have occurred at z>~6 however, direct observational tests of such a scenario are needed. We model starburst winds in the high-redshift universe and find that the fraction of space filled by enriched material varies strongly with the assumed star formation efficiency f* and the fraction of supernova energy powering each wind fesc. We show that metals carried by these winds can be seen in absorption against bright background sources, such as quasars or gamma-ray bursts, in narrow lines with characteristic equivalent widths ~0.5Åcoolant in the early universe and to study the initial mass function of stars at high redshifts.

  2. Correlation between the variation of the ionizing continuum and broad absorption lines

    Science.gov (United States)

    Lu, Wei-Jian; Lin, Ying-Ru; Qin, Yi-Ping

    2018-01-01

    In this Letter, we present an analysis of the relation between the variability of broad absorption lines (BALs) and that of the continuum. Our sample is multi-epoch observations of 483 quasars by the Sloan Digital Sky Survey-I/II/III (SDSS-I/II/III). We derive the fractional flux variations of the continuum and fractional equivalent width (EW) variations for C IV and Si IV BALs, and explore the correlations between the three. Our results reveal moderate anticorrelations with high significance level between the fractional flux variations of the continuum and fractional EW variations for both C IV and Si IV BALs. We also prove a significant positive correlation between the fractional EW variations for C IV and Si IV BALs, which is in agreement with several previous studies. Our discoveries can serve as evidence for the idea: Change of an ionizing continuum is the primary driver of BAL variability.

  3. Line-Shape Code Comparison through Modeling and Fitting of Experimental Spectra of the C ii 723-nm Line Emitted by the Ablation Cloud of a Carbon Pellet

    Directory of Open Access Journals (Sweden)

    Mohammed Koubiti

    2014-07-01

    Full Text Available Various codes of line-shape modeling are compared to each other through the profile of the C ii 723-nm line for typical plasma conditions encountered in the ablation clouds of carbon pellets, injected in magnetic fusion devices. Calculations were performed for a single electron density of 1017 cm−3 and two plasma temperatures (T = 2 and 4 eV. Ion and electron temperatures were assumed to be equal (Te = Ti = T. The magnetic field, B, was set equal to either to zero or 4 T. Comparisons between the line-shape modeling codes and two experimental spectra of the C ii 723-nm line, measured perpendicularly to the B-field in the Large Helical Device (LHD using linear polarizers, are also discussed.

  4. Quasar 2175 Å dust absorbers - II. Correlation analysis and relationship with other absorption line systems

    Science.gov (United States)

    Ma, Jingzhe; Ge, Jian; Prochaska, J. Xavier; Zhang, Shaohua; Ji, Tuo; Zhao, Yinan; Zhou, Hongyan; Lu, Honglin; Schneider, Donald P.

    2018-03-01

    We present the cold neutral content (H I and C I gas) of 13 quasar 2175 Å dust absorbers (2DAs) at z = 1.6-2.5 to investigate the correlation between the presence of the UV extinction bump with other physical characteristics. These 2DAs were initially selected from the Sloan Digital Sky Surveys I-III and followed up with the Keck-II telescope and the Multiple Mirror Telescope as detailed in our Paper I. We perform a correlation analysis between metallicity, redshift, depletion level, velocity width, and explore relationships between 2DAs and other absorption line systems. The 2DAs on average have higher metallicity, higher depletion levels, and larger velocity widths than Damped Lyman α absorbers (DLAs) or subDLAs. The correlation between [Zn/H] and [Fe/Zn] or [Zn/H] and logΔV90 can be used as alternative stellar mass estimators based on the well-established mass-metallicity relation. The estimated stellar masses of the 2DAs in this sample are in the range of ˜109 to ˜2 × 1011 M⊙ with a median value of ˜2 × 1010 M⊙. The relationship with other quasar absorption line systems can be described as (1) 2DAs are a subset of Mg II and Fe II absorbers, (2) 2DAs are preferentially metal-strong DLAs/subDLAs, (3) More importantly, all of the 2DAs show C I detections with logN(C I) > 14.0 cm-2, and (4) 2DAs can be used as molecular gas tracers. Their host galaxies are likely to be chemically enriched, evolved, massive (more massive than typical DLA/subDLA galaxies), and presumably star-forming galaxies.

  5. FIRST ULTRAVIOLET REFLECTANCE SPECTRA OF PLUTO AND CHARON BY THE HUBBLE SPACE TELESCOPE COSMIC ORIGINS SPECTROGRAPH: DETECTION OF ABSORPTION FEATURES AND EVIDENCE FOR TEMPORAL CHANGE

    Energy Technology Data Exchange (ETDEWEB)

    Stern, S. A.; Spencer, J. R.; Shinn, A. [Southwest Research Institute, 1050 Walnut Street, Boulder, CO 80302 (United States); Cunningham, N. J.; Hain, M. J., E-mail: astern@swri.edu [Nebraska Wesleyan University, 5000 Saint Paul Avenue, Lincoln, NE 68504 (United States)

    2012-01-15

    We have observed the mid-UV spectra of both Pluto and its large satellite, Charon, at two rotational epochs using the Hubble Space Telescope (HST) Cosmic Origins Spectrograph (COS) in 2010. These are the first HST/COS measurements of Pluto and Charon. Here we describe the observations and our reduction of them, and present the albedo spectra, average mid-UV albedos, and albedo slopes we derive from these data. These data reveal evidence for a strong absorption feature in the mid-UV spectrum of Pluto; evidence for temporal change in Pluto's spectrum since the 1990s is reported, and indirect evidence for a near-UV spectral absorption on Charon is also reported.

  6. Solvent effect on UV/Vis absorption and emission spectra in aqueous solution based on a modified form of solvent reorganization energy

    Science.gov (United States)

    Ren, HaiSheng; Ming, MeiJun; Zhu, Jun; Ma, JianYi; Li, XiangYuan

    2013-09-01

    In this Letter, novel form of solvatochromic shifts for absorption and emission spectra are proposed. As a typical test, the lowest transitions of s-trans-acrolein in aqueous solution are investigated. The obtained absorption solvent shift of 0.22 eV is in good agreement with the experimental value of 0.20 eV. In addition, we predict emission solvent shift of -0.16 eV. This value seems more reasonable comparing with the value of -0.12 eV by the traditional theory. The contributions to the shift are discussed and electrostatic polarization components are found to be crucial for electronic spectra of acrolein in water.

  7. Synthesis and investigation of solvent effects on the ultraviolet absorption spectra of 5-substituted-4-methyl-3-cyano-6-hydroxy-2-pyridones

    Directory of Open Access Journals (Sweden)

    NATASA V. VALENTIC

    2001-08-01

    Full Text Available A number of 5-substituted-4-methyl-3-cyano-6-hydroxy-2-pyridones from cyanoacetamide and the corresponding alkyl ethyl acetoacetates were synthesized according to modified literature procedures. The alkyl ethyl acetoacetates were obtained by the reaction of C-alkylation of ethyl acetoacetate. An investigation of the reaction conditions for the synthesis of 4-methyl-3-cyano-6-hydroxy-2-pyridone from cyanoacetamide and ethyl acetoacetate in eight different solvents was also performed. The ultraviolet absorption spectra of synthesized pyridones were measured in nine different solvents in the range 200–400 nm. The effects of solvent polarity and hydrogen bonding on the absorption spectra are interpreted by means of linear solvation energy relationships using a general equation of the form n = n0 + sp* + aa + bb, where p* is a measure of the solvent polarity, a is the scale of the solvent hydrogen bond donor acidities and b is the scale of the solvent hydrogen bond acceptor basicities.

  8. KOMBIP - a computer program for generation of Lorentzian/Gaussian line-shape and 'stick'-plot NMR spectra

    International Nuclear Information System (INIS)

    Aksnes, D.W.

    1971-01-01

    The program was written in order to obtain Lorentzian/Gaussian line-shape spectra and 'stick'-plots from a given set of transition frequencies and corresponding intensities using the CALCOMP graph-plotter. KOMBIP can be used either as a separate program or as a subroutine in connection with, for instance, the NMR computer programs LAOCOON II, LAOCN3, UEANMR II, UEAITR, LACX, and NMR IT. (Auth.)

  9. GOSPEG-1 a program for routine analysis of γ-ray spectra by an in line IBM S/7 computer

    International Nuclear Information System (INIS)

    Godio, G.P.; Gozzellino, F.

    1977-01-01

    In this paper a program for routine analysis of γ-ray spectra of samples coming from irradiated nuclear fuel reprocessing plant is described. An IBM S/7 computer (SK words of memory) which is installed at the CNEN-EUREX reprocessing plant and which is in-line connected with a multichannel analyzer and Ge(Li) detector, has been utilized for this work. The program has been written in Assembler S/7 language

  10. Cataloguing Emission Line Spectra from Fe VII-Fe XXIV in the Extreme Ultraviolet

    Science.gov (United States)

    Lepson, J. K.; Beiersdorfer, P.; Brown, G. V.; Kahn, D. A.; Liedahl, D. A.; Mauche, C. W.; Utter, S. B.

    2000-01-01

    Detailed laboratory astrophysics measurements are, in progress to produce spectral tables for the Fe VII Fe XXIV line emission in the EUV wavelength band. Results for Fe XIII are presented that update line lists used in the Chandra Emission Line Project.

  11. ORFEUS II echelle spectra : On the H-2/CO ratio in LMC gas towards LH 10

    NARCIS (Netherlands)

    Richter, P; de Boer, K; Bomans, DJ; Chin, YN; Heithausen, A; Koornneef, J

    1999-01-01

    ORFEUS far UV echelle spectra have been used to investigate HI, Hz and CO absorption lines along the line of sight towards LH 10:3120 in the LMC, extending the study presented by de Beer et al. (1998). While Hz absorption is clearly visible, no CO absorption at LMC velocities is detected, but an

  12. AN INFRARED EXCESS IDENTIFIED IN RADIO-LOUD BROAD ABSORPTION LINE QUASARS

    Energy Technology Data Exchange (ETDEWEB)

    DiPompeo, M. A.; Runnoe, J. C.; Brotherton, M. S.; Myers, A. D. [Department of Physics and Astronomy 3905, University of Wyoming, 1000 East University, Laramie, WY 82071 (United States)

    2013-01-10

    If broad absorption line (BAL) quasars represent a high-covering-fraction evolutionary state (even if this is not the sole factor governing the presence of BALs), it is expected that they should show an excess of mid-infrared radiation compared to normal quasars. Some previous studies have suggested that this is not the case. We perform the first analysis of the IR properties of radio-loud BAL quasars, using IR data from WISE and optical (rest-frame ultraviolet) data from SDSS, and compare the BAL quasar sample with a well-matched sample of unabsorbed quasars. We find a statistically significant excess in the mid- to near-infrared luminosities of BAL quasars, particularly at rest-frame wavelengths of 1.5 and 4 {mu}m. Our sample was previously used to show that BALs are observed along many lines of sight toward quasars, but with an overabundance of more edge-on sources, suggesting that orientation factors into the appearance of BALs. The evidence here-of a difference in IR luminosities between BAL quasars and unabsorbed quasars-can be ascribed to evolution. This suggests that a merging of the current BAL paradigms is needed to fully describe the class.

  13. BROAD ABSORPTION LINE DISAPPEARANCE ON MULTI-YEAR TIMESCALES IN A LARGE QUASAR SAMPLE

    Energy Technology Data Exchange (ETDEWEB)

    Filiz Ak, N.; Brandt, W. N.; Schneider, D. P. [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States); Hall, P. B. [Department of Physics and Astronomy, York University, 4700 Keele St., Toronto, Ontario M3J 1P3 (Canada); Anderson, S. F.; Gibson, R. R. [Astronomy Department, University of Washington, Seattle, WA 98195 (United States); Lundgren, B. F. [Department of Physics, Yale University, New Haven, CT 06511 (United States); Myers, A. D. [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); Petitjean, P. [Institut d' Astrophysique de Paris, Universite Paris 6, F-75014, Paris (France); Ross, Nicholas P. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 92420 (United States); Shen Yue [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-51, Cambridge, MA 02138 (United States); York, D. G. [Department of Astronomy and Astrophysics, and Enrico Fermi Institute, University of Chicago, 5640 S. Ellis Ave., Chicago, IL 60637 (United States); Bizyaev, D.; Brinkmann, J.; Malanushenko, E.; Oravetz, D. J.; Pan, K.; Simmons, A. E. [Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349-0059 (United States); Weaver, B. A., E-mail: nfilizak@astro.psu.edu [Center for Cosmology and Particle Physics, New York University, New York, NY 10003 (United States)

    2012-10-01

    We present 21 examples of C IV broad absorption line (BAL) trough disappearance in 19 quasars selected from systematic multi-epoch observations of 582 bright BAL quasars (1.9 < z < 4.5) by the Sloan Digital Sky Survey-I/II (SDSS-I/II) and SDSS-III. The observations span 1.1-3.9 yr rest-frame timescales, longer than have been sampled in many previous BAL variability studies. On these timescales, Almost-Equal-To 2.3% of C IV BAL troughs disappear and Almost-Equal-To 3.3% of BAL quasars show a disappearing trough. These observed frequencies suggest that many C IV BAL absorbers spend on average at most a century along our line of sight to their quasar. Ten of the 19 BAL quasars showing C IV BAL disappearance have apparently transformed from BAL to non-BAL quasars; these are the first reported examples of such transformations. The BAL troughs that disappear tend to be those with small-to-moderate equivalent widths, relatively shallow depths, and high outflow velocities. Other non-disappearing C IV BALs in those nine objects having multiple troughs tend to weaken when one of them disappears, indicating a connection between the disappearing and non-disappearing troughs, even for velocity separations as large as 10,000-15,000 km s{sup -1}. We discuss possible origins of this connection including disk-wind rotation and changes in shielding gas.

  14. Determining CDOM Absorption Spectra in Diverse Coastal Environments Using a Multiple Pathlength, Liquid Core Waveguide System. Measuring the Absorption of CDOM in the Field Using a Multiple Pathlength Liquid Waveguide System

    Science.gov (United States)

    Miller, Richard L.; Belz, Mathias; DelCastillo, Carlos; Trzaska, Rick

    2000-01-01

    We evaluated the accuracy, sensitivity and precision of a multiple pathlength, liquid core waveguide (MPLCW) system for measuring colored dissolved organic matter (CDOM) absorption in the UV-visible spectral range (370-700 nm). The MPLCW has four optical paths (2.0, 9.8, 49.3, and 204 cm) coupled to a single Teflon AF sample cell. Water samples were obtained from inland, coastal and ocean waters ranging in salinity from 0 to 36 PSU. Reference solutions for the MPLCW were made having a refractive index of the sample. CDOM absorption coefficients, a(sub CDOM), and the slope of the log-linearized absorption spectra, S, were compared with values obtained using a dual-beam spectrophotometer. Absorption of phenol red secondary standards measured by the MPLCW at 558 nm were highly correlated with spectrophotometer values (r > 0.99) and showed a linear response across all four pathlengths. Values of a(sub CDOM) measured using the MPLCW were virtually identical to spectrophotometer values over a wide range of concentrations. The dynamic range of a(sub CDOM) for MPLCW measurements was 0.002 - 231.5/m. At low CDOM concentrations (a(sub 370) < 0.1/m) spectrophotometric a(sub CDOM) were slightly greater than MPLCW values and showed larger fluctuations at longer wavelengths due to limitations in instrument precision. In contrast, MPLCW spectra followed an exponential to 600 nm for all samples. The maximum deviation in replicate MPLCW spectra was less than 0.001 absorbance units. The portability, sampling, and optical characteristics of a MPLCW system provide significant enhancements for routine CDOM absorption measurements in a broad range of natural waters.

  15. Effect of ligand nature and geometry of its surrounding on electron absorption spectra of NpO22+ and PuO22+ compounds

    International Nuclear Information System (INIS)

    Sokolov, E.I.; Tebelev, L.G.; Melkaya, R.F.; Rykov, A.G.

    1981-01-01

    Electron absorption spectra of actinide compounds with the symmetry of the nearest surrounding of actinyl-ions as follows: Dsub(2h)-AnO 2 (NO 3 ) 2 xnH 2 O, AnO 2 (CH 3 COO) 2 x2H 2 O; Dsub(3h)-MAnO 2 (NO 3 ) 3 (M-K, Rb, Cs), NaAnO 2 (CH 3 COO) 3 , (NH 4 ) 4 AnO 2 (CO 3 ) 3 ; Dsub(4h)-Cs 2 AnO 2 Cl 4 , where An-U, Np, Pb, are measured at room temperature. It is established that position, intensity and form of absorption bands in neptunyl compound spectra are sensible equally to geometry of coordination sphere and to ligand nature. The character of the change of plutonyl compound spectra is the same as of neptunyl ones: it is determined both by surrounding geometry and chemical nature of ligands. It is shown that in the near infrared region ligand effect on plutonyl compound spectra with the symmetry of anion complex Dsub(3h) is weaker than in the visible region

  16. Molecular-orbital studies via satellite-free x-ray fluorescence: Cl K absorption and K--valence-level emission spectra of chlorofluoromethanes

    International Nuclear Information System (INIS)

    Perera, R.C.C.; Cowan, P.L.; Lindle, D.W.; LaVilla, R.E.; Jach, T.; Deslattes, R.D.

    1991-01-01

    X-ray absorption and emission measurements in the vicinity of the chlorine K edge of the three chlorofluoromethanes have been made using monochromatic synchrotron radiation as the source of excitation. By selectively tuning the incident radiation to just above the Cl 1s single-electron ionization threshold for each molecule, less complex x-ray-emission spectra are obtained. This reduction in complexity is attributed to the elimination of multielectron transitions in the Cl K shell, which commonly produce satellite features in x-ray emission. The resulting ''satellite-free'' x-ray-emission spectra exhibit peaks due only to electrons in valence molecular orbitals filling a single Cl 1s vacancy. These simplified emission spectra and the associated x-ray absorption spectra are modeled using straightforward procedures and compared with semiempirical ground-state molecular-orbital calculations. Good agreement is observed between the present experimental and theoretical results for valence-orbital energies and those obtained from ultraviolet photoemission, and between relative radiative yields determined both experimentally and theoretically in this work

  17. Influence of TiO2 Nanocrystals Fabricating Dye-Sensitized Solar Cell on the Absorption Spectra of N719 Sensitizer

    Directory of Open Access Journals (Sweden)

    Puhong Wen

    2012-01-01

    Full Text Available The absorption spectra of N719 sensitizer anchored on the films prepared by TiO2 nanocrystals with different morphology and size were investigated for improving the performance of dye-sensitized solar cell (DSC. We find that the morphology and size of TiO2 nanocrystals can affect the UV-vis and FT-IR spectra of the sensitizer anchored on their surfaces. In particular, the low-energy metal-to-ligand charge-transfer transitions (MLCT band in the visible absorption spectra of N719 is strongly affected, and locations of these MLCT bands revealed larger differences. The results indicate that there is a red shift of MLCT band in the spectra obtained by using TiO2 nanocrystals with long morphology and large size compared to that in solution. And it produced a larger red-shift on the MLCT band after TiO2 nanocrystals with small size mixed with some long nanocrystals. Accordingly, the utilization rate to visible light is increased. This is a reason why the DSC prepared by using such film as a photoelectrode has better performance than before mixing.

  18. Vibrational, X-ray absorption, and Mössbauer spectra of sulfate minerals from the weathered massive sulfide deposit at Iron Mountain, California

    Science.gov (United States)

    Majzlan, Juraj; Alpers, Charles N.; Bender Koch, Christian; McCleskey, R. Blaine; Myneni, Satish B.C.; Neil, John M.

    2014-01-01

    The Iron Mountain Mine Superfund site in California is a prime example of an acid mine drainage (AMD) system with well developed assemblages of sulfate minerals typical for such settings. Here we present and discuss the vibrational (infrared), X-ray absorption, and Mössbauer spectra of a number of these phases, augmented by spectra of a few synthetic sulfates related to the AMD phases. The minerals and related phases studied in this work are (in order of increasing Fe2O3/FeO): szomolnokite, rozenite, siderotil, halotrichite, römerite, voltaite, copiapite, monoclinic Fe2(SO4)3, Fe2(SO4)3·5H2O, kornelite, coquimbite, Fe(SO4)(OH), jarosite and rhomboclase. Fourier transform infrared spectra in the region 750–4000 cm−1 are presented for all studied phases. Position of the FTIR bands is discussed in terms of the vibrations of sulfate ions, hydroxyl groups, and water molecules. Sulfur K-edge X-ray absorption near-edge structure (XANES) spectra were collected for selected samples. The feature of greatest interest is a series of weak pre-edge peaks whose position is determined by the number of bridging oxygen atoms between Fe3+ octahedra and sulfate tetrahedra. Mössbauer spectra of selected samples were obtained at room temperature and 80 K for ferric minerals jarosite and rhomboclase and mixed ferric–ferrous minerals römerite, voltaite, and copiapite. Values of Fe2+/[Fe2+ + Fe3+] determined by Mössbauer spectroscopy agree well with those determined by wet chemical analysis. The data presented here can be used as standards in spectroscopic work where spectra of well-characterized compounds are required to identify complex mixtures of minerals and related phases.

  19. A far wing line shape theory and its application to the foreign-broadened water continuum absorption. III

    Science.gov (United States)

    Ma, Q.; Tipping, R. H.

    1992-01-01

    The far wing line shape theory developed previously and applied to the calculation of the continuum absorption of pure water vapor is extended to foreign-broadened continua. Explicit results are presented for H2O-N2 and H2O-CO2 in the frequency range from 0 to 10,000/cm. For H2O-N2 the positive and negative resonant frequency average line shape functions and absorption coefficients are computed for a number of temperatures between 296 and 430 K for comparison with available laboratory data. In general the agreement is very good.

  20. Experimental and theoretical studies of the VUV emission and absorption spectra of H{sub 2}, HD and D{sub 2} molecules; Etude experimentale et theorique des spectres d'emission et d'absorption VUV des molecules H{sub 2}, D{sub 2} et HD

    Energy Technology Data Exchange (ETDEWEB)

    Roudjane, M

    2007-12-15

    The aim of this thesis is to carry out an experimental study of the absorption and emission spectra of the D{sub 2} and HD isotopes, with high resolution, in the VUV domain and to supplement it by a theoretical study of the excited electronic states involved in the observed transitions. The emission spectra of HD and D{sub 2} are produced by Penning discharge source operating under low pressure and are recorded in the spectral range 78 - 170 nm. The recorded spectra contains more than 20.000 lines. The analysis of the spectrum consists in identifying and assigning the lines to the electronic transitions between energy levels of the molecule. The present analysis is based on our theoretical calculations of the ro-vibrational energy levels of the excited electronic states and the transition probabilities from these states towards the energy levels of the fundamental state. The theoretical results are obtained by resolving the coupled equations between the excited electronic states B{sup 1}{sigma}{sub u}{sup 1}, B'{sup 1}{sigma}{sub u}{sup 1}, C{sup 1}{pi}{sub u}{sup 1} and D{sup 1}{pi}{sub u}{sup 1}, taking into account the nonadiabatic couplings between these states, and they are obtained in the adiabatic approximation for the excited electronic states B''B-bar{sup 1}{sigma}{sub u}{sup +}, D'{sup 1}{pi}{sub u}{sup 1} and D''{sup 1}{pi}{sub u}{sup 1}. The equations are resolved using a modern method based on the discretization variables representation method. In addition, we have carried out a study of the absorption spectra of the HD and D{sub 2} molecules.

  1. Naturally enhanced ion-line spectra around the equatorial 150-km region

    Directory of Open Access Journals (Sweden)

    J. L. Chau

    2009-03-01

    Full Text Available For many years strong radar echoes coming from 140–170 km altitudes at low latitudes have been associated to the existence of field-aligned irregularities (FAIs (the so called 150-km echoes. In this work, we present frequency spectra as well as angular distribution of 150-km echoes. When the 150-km region is observed with beams perpendicular to the magnetic field (B the observed radar spectra are very narrow with spectral widths between 3–12 m/s. On the other hand, when few-degrees off-perpendicular beams are used, the radar spectra are wide with spectral widths comparable to those expected from ion-acoustic waves at these altitudes (>1000 m/s. Moreover the off-perpendicular spectral width increases with increasing altitude. The strength of the received echoes is one to two orders of magnitude stronger than the expected level of waves in thermal equilibrium at these altitudes. Such enhancement is not due to an increase in electron density. Except for the enhancement in power, the spectra characteristics of off-perpendicular and perpendicular echoes are in reasonable agreement with expected incoherent scatter spectra at these angles and altitudes. 150-km echoes are usually observed in narrow layers (2 to 5. Bistatic common volume observations as well as observations made few kilometers apart show that, for most of the layers, there is very high correlation on power fluctuations without a noticeable time separation between simultaneous echoes observed with Off-perpendicular and Perpendicular beams. However, in one of the central layers, the echoes are the strongest in the perpendicular beam and absent or very weak in the off-perpendicular beams, suggesting that they are generated by a plasma instability. Our results indicate that most echoes around 150-km region are not as aspect sensitive as originally thought, and they come from waves that have been enhanced above waves in thermal equilibrium.

  2. A model for persistent hole burned spectra and hole growth kinetics that includes photoproduct absorption: Application to free base phthalocyanine in hyperquenched glassy ortho-dichlorobenzene at 5 K

    International Nuclear Information System (INIS)

    Reinot, T.; Dang, N.C.; Small, G.J.

    2003-01-01

    Persistent nonphotochemical and photochemical hole burning of the S 0 →S 1 origin absorption bands of chromophores in amorphous hosts such as glasses, polymers and proteins at low temperatures have been used to address a number of problems that range from structural disorder and configurational tunneling to excitation energy transfer and charge separation in photosynthetic complexes. Often the hole burned spectra are interfered by photoproduct (antihole) absorption. To date there has been no systematic approach to modeling hole burned spectra and the dispersive kinetics of zero-phonon hole growth that accounts for the antihole. A 'master' equation that does so is presented. A key ingredient of the equation is a time-dependent, two-dimensional site excitation frequency distribution function (SDF) of the zero-phonon lines. Prior to hole burning (t=0) the SDF is that of the educt sites. For t>0 the SDF describes both educt and photoproduct sites and allows for burning of the latter that revert to the educt sites from which they originate (light-induced hole filling). Our model includes linear electron-phonon coupling and the three distributions that lead to dispersive hole growth kinetics, the most important of which is the distribution for the parameter λ associated with tunneling between the bistable configurations of the chromophore-host system that are interconverted by hole burning. The master equation is successfully applied to free base phthalocyanine (Pc) in hyperquenched glassy ortho-dichlorobenzene (DCB) at 5 K. The mechanism of hole burning is photochemical and involves tautomerization of the two protons at the center of the macrocycle (Pc) that occurs in the S 1 (Q x ) and/or T 1 (Q x ) state of Pc. A single set of parameter values (some of which are determined directly from the hole burned spectra) provides a satisfactory description of the dependence of the hole burned spectra and hole growth kinetics on the location of the burn frequency within the

  3. Absorption and emission line shapes in the O(2) atmospheric bands: Theoretical model and limb viewing simulations.

    Science.gov (United States)

    Abreu, V J; Bucholtz, A; Hays, P B; Ortland, D; Skinner, W R; Yee, J H

    1989-06-01

    A multiple scattering radiative transfer model has been developed to carry out a line by line calculation of the absorption and emission limb measurements that will be made by the High Resolution Doppler Imager to be flown on the Upper Atmosphere Research Satellite. The multiple scattering model uses the doubling and adding methods to solve the radiative transfer equation, modified to take into account a spherical inhomogeneous atmosphere. Representative absorption and emission line shapes in the O(2)((1)Sigma(+)(g)-(3)Sigma(-)(g)) atmospheric bands (A, B, and gamma) and their variation with altitude are presented. The effects of solar zenith angle, aerosol loading, surface albedo, and cloud height on the line shapes are also discussed.

  4. Ultraviolet and infrared absorption spectra of Cr2O3 doped-sodium metaphosphate, lead metaphosphate and zinc metaphosphate glasses and effects of gamma irradiation: a comparative study.

    Science.gov (United States)

    Marzouk, M A; ElBatal, F H; Abdelghany, A M

    2013-10-01

    The effects of gamma irradiation on spectral properties of Cr2O3-doped phosphate glasses of three varieties, namely sodium metaphosphate, lead metaphosphate and zinc metaphosphate have been investigated. Optical spectra of the undoped samples reveal strong UV absorption bands which are attributed to the presence of trace iron impurities in both the sodium and zinc phosphate glasses while the lead phosphate glass exhibits broad UV near visible bands due to combined absorption of both trace iron impurities and divalent lead ions. The effect of chromium oxide content has been investigated. The three different Cr2O3-doped phosphate glasses reveal spectral visible bands varying in their position and intensity and splitting due to the different field strengths of the Na(+), Pb(2+), Zn(2+) cations, together with the way they are housed in the network and their effects on the polarisability of neighboring oxygens ligands. The effects of gamma irradiation on the optical spectral properties of the various glasses have been compared. The different effects for lead and zinc phosphate are related to the ability of Pb(2+), and Zn(2+) to form additional structural units causing stability of the network towards gamma irradiation. Also, the introduction of the transition metal chromium ions reveals some shielding behavior towards irradiation. Infrared absorption spectra of the three different base phosphate glasses show characteristic vibrations due to various phosphate groups depending on the type of glass and Cr2O3 is observed to slightly affect the IR spectra. Gamma irradiation causes minor variations in some of the intensities of the IR spectra but the main characteristic bands due to phosphate groups remain in their number and position. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. FAR-INFRARED LINE SPECTRA OF SEYFERT GALAXIES FROM THE HERSCHEL-PACS SPECTROMETER

    Energy Technology Data Exchange (ETDEWEB)

    Spinoglio, Luigi; Pereira-Santaella, Miguel; Busquet, Gemma [Istituto di Astrofisica e Planetologia Spaziali, INAF, Via Fosso del Cavaliere 100, I-00133 Roma (Italy); Dasyra, Kalliopi M. [Observatoire de Paris, LERMA (CNRS:UMR8112), 61 Av. de l' Observatoire, F-75014, Paris (France); Calzoletti, Luca [Agenzia Spaziale Italiana (ASI) Science Data Center, I-00044 Frascati (Roma) (Italy); Malkan, Matthew A. [Astronomy Division, University of California, Los Angeles, CA 90095-1547 (United States); Tommasin, Silvia, E-mail: luigi.spinoglio@iaps.inaf.it [Weizmann Institute of Science, Department of Neurobiology, Rehovot 76100 (Israel)

    2015-01-20

    We observed the far-IR fine-structure lines of 26 Seyfert galaxies with the Herschel-PACS spectrometer. These observations are complemented with Spitzer Infrared Spectrograph and Herschel SPIRE spectroscopy. We used the ionic lines to determine electron densities in the ionized gas and the [C I] lines, observed with SPIRE, to measure the neutral gas densities, while the [O I] lines measure the gas temperature, at densities below ∼10{sup 4} cm{sup –3}. Using the [O I]145 μm/63 μm and [S III]33/18 μm line ratios, we find an anti-correlation of the temperature with the gas density. Various fine-structure line ratios show density stratifications in these active galaxies. On average, electron densities increase with the ionization potential of the ions. The infrared lines arise partly in the narrow line region, photoionized by the active galactic nucleus (AGN), partly in H II regions photoionized by hot stars, and partly in photo-dissociated regions. We attempt to separate the contributions to the line emission produced in these different regions by comparing our observed emission line ratios to theoretical values. In particular, we tried to separate the contribution of AGNs and star formation by using a combination of Spitzer and Herschel lines, and we found that besides the well-known mid-IR line ratios, the line ratio of [O III]88 μm/[O IV]26 μm can reliably discriminate the two emission regions, while the far-IR line ratio of [C II]157 μm/[O I]63 μm is only able to mildly separate the two regimes. By comparing the observed [C II]157 μm/[N II]205 μm ratio with photoionization models, we also found that most of the [C II] emission in the galaxies we examined is due to photodissociation regions.

  6. Infrared absorption spectra of gaseous HD. II. Collision-induced fundamental band of HD in HD--Ne and HD--Ar mixtures at room temperature

    International Nuclear Information System (INIS)

    Prasad, R.D.G.; Reddy, S.P.

    1976-01-01

    The collision-induced infrared absorption spectra of the fundamental band of HD in binary mixtures of HD with Ne and Ar at room temperature have been studied with an absorption path length of 105.2 cm for different base densities of HD in the range 8--20 amagat and a number of total gas densities up to 175 amagat. The observed features of the profiles of the enhancement of absorption in these mixtures resemble closely those of the corresponding profiles of the fundamental band of H 2 in binary mixtures with Ne and Ar. The binary absorption coefficients of the band obtained from the measured integrated intensities are (1.84 +- 0.06) x 10 -35 and (4.41 +- 0.06) x 10 -35 cm 6 s -1 for HD--Ne and HD--Ar, respectively. The characteristic half-width parameters, delta/subd/ and delta/subc/ of the overlap transitions and delta/subq/ (and delta/subq//sub prime/) of the quadrupolar transitions, are obtained from an analysis of the profiles of the enhancement of absorption in both these mixtures. The quantity delta/subc/ which is the half-width of the intercollisional interference dip of the Q branch increases with the density of the perturbing gas Ne or Ar, and for HD--Ne it varies in a manner similar to that for HD--He as described in Paper I of this series

  7. The SAURON project - XI. Stellar populations from absorption-line strength maps of 24 early-type spirals

    NARCIS (Netherlands)

    Peletier, Reynier F.; Falcon-Barroso, Jesus; Bacon, Roland; Cappellari, Michele; Davies, Roger L.; de Zeeuw, P. T.; Emsellem, Eric; Ganda, Katia; Krajnovic, Davor; Kuntschner, Harald; McDermid, Richard M.; Sarzi, Marc; van de Ven, Glenn

    2007-01-01

    We present absorption-line strength maps of a sample of 24 representative early-type spiral galaxies, mostly of type Sa, obtained as part of the SAURON (Spectrographic Areal Unit for Research on Optical Nebulae) survey of nearby galaxies using our custom-built integral-field spectrograph. Using

  8. Skylab ultraviolet stellar spectra - Emission lines from the Beta Lyrae system

    Science.gov (United States)

    Kondo, Y.; Parsons, S. B.; Wray, J. D.; Benedict, G. F.; Henize, K. G.; Mccluskey, G. E.

    1976-01-01

    Observations of Beta Lyr with the Skylab S-019 ultraviolet objective-prism spectrograph show numerous emission lines in the region from 1400 to 2300 A. Some variations in line strength between phases 0.25 and 0.50 are seen, which probably explain the shallowness of the OAO-2 light curve at 1910 A. Many of the emission lines are probably due to intercombination transitions, thus confirming the concept that the emission is produced by collisional excitation in low-density clouds of hot gas.

  9. On-line Zeeman atomic absorption spectroscopy for mercury analysis in oil shale gases. Final report

    Energy Technology Data Exchange (ETDEWEB)

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

    1979-08-01

    The technique utilizes ZAA for on-line measurement of mercury in the presence of smoke, organic vapors, and oil mist in offgases from oil shale processing plants. The spectrometer utilizes a new flow-through stainless steel (SS) furnace maintained at 900/sup 0/C by joule heating. Corrosion of the furnace by H/sub 2/S in the sample gas is minimized by diffusion of Al into the surface of the SS. Corrosion tests with 2% (v/v) H/sub 2/S at 1093/sup 0/C gave an estimated furnace lifetime of three days. The instrumental response with this furnace is characterized by a detection limit (DL) of 2 ppB, a linear response up to 100 ppB, and a precision of +- 7% or better. In the 50 ppB to 1.6 ppM range a furnace with a 5 cm optical absorption tube yields a DL of 10 ppB, a linear response up to 800 ppB, and a precision of +- 10% or better. Sample gas flow rates can be varied between 400 and 4000 scc/min for either furance.

  10. The investigation of hydrogens bonds between sulphur-bearing heterocyclic and proton-donor compounds by IR absorption spectra

    International Nuclear Information System (INIS)

    Narziev, B.N.; Nurulloev, M.; Makhkambaev, D.

    1982-01-01

    In this article the results of intermolecular interaction study of sulfur-containing heterocyclic (thiophene, thiophane) and proton-donar (water, alcohol, carbonic acids, chlorophon) molecules for measuring of IR spectrum absorption of protondonar compounds in soluted shape are presented

  11. DFT study of electron absorption and emission spectra of pyramidal LnPc(OAc) complexes of some lanthanide ions in the solid state

    Science.gov (United States)

    Hanuza, J.; Godlewska, P.; Lisiecki, R.; Ryba-Romanowski, W.; Kadłubański, P.; Lorenc, J.; Łukowiak, A.; Macalik, L.; Gerasymchuk, Yu.; Legendziewicz, J.

    2018-05-01

    The electron absorption and emission spectra were measured for the pyramidal LnPc(OAc) complexes in the solid state and co-doped in silica glass, where Ln = Er, Eu and Ho. The theoretical electron spectra were determined from the quantum chemical DFT calculation using four approximations CAM-B3LYP/LANL2DZ, CAM-B3LYP/CC-PVDZ, B3LYP/LANL2DZ and B3LYP/CC-PVDZ. It was shown that the best agreement between the calculated and experimental structural parameters and spectroscopic data was reached for the CAM-B3LYP/LANL2DZ model. The emission spectra were measured using the excitations both in the ligand and lanthanide absorption ranges. The possibility of energy transfer between the phthalocyanine ligand and excited states of lanthanide ions was discussed. It was shown that the back energy transfer from metal states to phthalocyanine state is responsible for the observed emission of the studied complexes both in the polycrystalline state and silica glass.

  12. DFT study of electron absorption and emission spectra of pyramidal LnPc(OAc) complexes of some lanthanide ions in the solid state.

    Science.gov (United States)

    Hanuza, J; Godlewska, P; Lisiecki, R; Ryba-Romanowski, W; Kadłubański, P; Lorenc, J; Łukowiak, A; Macalik, L; Gerasymchuk, Yu; Legendziewicz, J

    2018-05-05

    The electron absorption and emission spectra were measured for the pyramidal LnPc(OAc) complexes in the solid state and co-doped in silica glass, where Ln=Er, Eu and Ho. The theoretical electron spectra were determined from the quantum chemical DFT calculation using four approximations CAM-B3LYP/LANL2DZ, CAM-B3LYP/CC-PVDZ, B3LYP/LANL2DZ and B3LYP/CC-PVDZ. It was shown that the best agreement between the calculated and experimental structural parameters and spectroscopic data was reached for the CAM-B3LYP/LANL2DZ model. The emission spectra were measured using the excitations both in the ligand and lanthanide absorption ranges. The possibility of energy transfer between the phthalocyanine ligand and excited states of lanthanide ions was discussed. It was shown that the back energy transfer from metal states to phthalocyanine state is responsible for the observed emission of the studied complexes both in the polycrystalline state and silica glass. Copyright © 2018. Published by Elsevier B.V.

  13. A time-dependent density-functional theory and complete active space self-consistent field method study of vibronic absorption and emission spectra of coumarin.

    Science.gov (United States)

    Li, Junfeng; Rinkevicius, Zilvinas; Cao, Zexing

    2014-07-07

    Time-dependent density-functional theory (TD-DFT) and complete active space multiconfiguration self-consistent field (CASSCF) calculations have been used to determine equilibrium structures and vibrational frequencies of the ground state and several singlet low-lying excited states of coumarin. Vertical and adiabatic transition energies of S1, S2, and S3 have been estimated by TD-B3LYP and CASSCF/PT2. Calculations predict that the dipole-allowed S1 and S3 states have a character of (1)(ππ*), while the dipole-forbidden (1)(nπ*) state is responsible for S2. The vibronic absorption and emission spectra of coumarin have been simulated by TD-B3LYP and CASSCF calculations within the Franck-Condon approximation, respectively. The simulated vibronic spectra show good agreement with the experimental observations available, which allow us to reasonably interpret vibronic features in the S0→S1 and S0→S3 absorption and the S0←S1 emission spectra. Based on the calculated results, activity, intensity, and density of the vibronic transitions and their contribution to the experimental spectrum profile have been discussed.

  14. Impact effects of gamma irradiation on the optical and FT infrared absorption spectra of some Nd3+-doped soda lime phosphate glasses

    Science.gov (United States)

    Marzouk, M. A.; Elkashef, I. M.; Elbatal, H. A.

    2018-04-01

    The main aim of the present work is to study by two collective optical and FTIR spectral measurements some prepared Nd2O3-doped soda lime phosphate glasses before and after gamma irradiation with dose (9 Mrad). The spectral data reveal two strong UV absorption peaks which are correlated with unavoidable trace iron impurities beside extended additional characteristic bands due to Nd3+ ions. Gamma irradiation on the undoped glass produces slight decrease of the intensity of the UV absorption and the generation of an induced visible band and these effects are controlled with two photochemical reduction of some Fe3+ ions to Fe2+ ions together with the formation of nonbridging oxygen hole center (NBOHC) or phosphorous oxygen hole center (POHC). The impact effect of gamma irradiation on the spectra of Nd2O3-doped glasses is limited due to suggested shielding behavior of neodymium ions. FT-infrared spectra show vibrational modes due to main Q2-Q3 phosphate groups and the response of gamma irradiation of the IR spectra is low and the limited variations are related to suggested changes in some bond angles and bond lengths which cause the observed decrease to the intensities of some IR bands.

  15. NARROW Na AND K ABSORPTION LINES TOWARD T TAURI STARS: TRACING THE ATOMIC ENVELOPE OF MOLECULAR CLOUDS

    Energy Technology Data Exchange (ETDEWEB)

    Pascucci, I.; Simon, M. N. [Lunar and Planetary Laboratory, The University of Arizona, Tucson, AZ 85721 (United States); Edwards, S. [Five College Astronomy Department, Smith College, Northampton, MA 01063 (United States); Heyer, M. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003-9305 (United States); Rigliaco, E. [Institute for Astronomy, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich (Switzerland); Hillenbrand, L. [Department of Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Gorti, U.; Hollenbach, D., E-mail: pascucci@lpl.arizona.edu [SETI Institute, Mountain View, CA 94043 (United States)

    2015-11-20

    We present a detailed analysis of narrow Na i and K i absorption resonance lines toward nearly 40 T Tauri stars in Taurus with the goal of clarifying their origin. The Na i λ5889.95 line is detected toward all but one source, while the weaker K i λ7698.96 line is detected in about two-thirds of the sample. The similarity in their peak centroids and the significant positive correlation between their equivalent widths demonstrate that these transitions trace the same atomic gas. The absorption lines are present toward both disk and diskless young stellar objects, which excludes cold gas within the circumstellar disk as the absorbing material. A comparison of Na i and CO detections and peak centroids demonstrates that the atomic gas and molecular gas are not co-located, the atomic gas being more extended than the molecular gas. The width of the atomic lines corroborates this finding and points to atomic gas about an order of magnitude warmer than the molecular gas. The distribution of Na i radial velocities shows a clear spatial gradient along the length of the Taurus molecular cloud filaments. This suggests that absorption is associated with the Taurus molecular cloud. Assuming that the gradient is due to cloud rotation, the rotation of the atomic gas is consistent with differential galactic rotation, whereas the rotation of the molecular gas, although with the same rotation axis, is retrograde. Our analysis shows that narrow Na i and K i absorption resonance lines are useful tracers of the atomic envelope of molecular clouds. In line with recent findings from giant molecular clouds, our results demonstrate that the velocity fields of the atomic and molecular gas are misaligned. The angular momentum of a molecular cloud is not simply inherited from the rotating Galactic disk from which it formed but may be redistributed by cloud–cloud interactions.

  16. NARROW Na AND K ABSORPTION LINES TOWARD T TAURI STARS: TRACING THE ATOMIC ENVELOPE OF MOLECULAR CLOUDS

    International Nuclear Information System (INIS)

    Pascucci, I.; Simon, M. N.; Edwards, S.; Heyer, M.; Rigliaco, E.; Hillenbrand, L.; Gorti, U.; Hollenbach, D.

    2015-01-01

    We present a detailed analysis of narrow Na i and K i absorption resonance lines toward nearly 40 T Tauri stars in Taurus with the goal of clarifying their origin. The Na i λ5889.95 line is detected toward all but one source, while the weaker K i λ7698.96 line is detected in about two-thirds of the sample. The similarity in their peak centroids and the significant positive correlation between their equivalent widths demonstrate that these transitions trace the same atomic gas. The absorption lines are present toward both disk and diskless young stellar objects, which excludes cold gas within the circumstellar disk as the absorbing material. A comparison of Na i and CO detections and peak centroids demonstrates that the atomic gas and molecular gas are not co-located, the atomic gas being more extended than the molecular gas. The width of the atomic lines corroborates this finding and points to atomic gas about an order of magnitude warmer than the molecular gas. The distribution of Na i radial velocities shows a clear spatial gradient along the length of the Taurus molecular cloud filaments. This suggests that absorption is associated with the Taurus molecular cloud. Assuming that the gradient is due to cloud rotation, the rotation of the atomic gas is consistent with differential galactic rotation, whereas the rotation of the molecular gas, although with the same rotation axis, is retrograde. Our analysis shows that narrow Na i and K i absorption resonance lines are useful tracers of the atomic envelope of molecular clouds. In line with recent findings from giant molecular clouds, our results demonstrate that the velocity fields of the atomic and molecular gas are misaligned. The angular momentum of a molecular cloud is not simply inherited from the rotating Galactic disk from which it formed but may be redistributed by cloud–cloud interactions

  17. X-ray spectra of Hercules X-1. 1: Iron line fluorescence from a subrelativistic shell

    Science.gov (United States)

    Pravdo, S. H.; Becker, R. H.; Boldt, E. A.; Holt, S. S.; Serlemitsos, P. J.; Swank, J. H.

    1977-01-01

    The X-ray spectrum of Hercules X-1 was observed in the energy range 2-24 keV from August 29 to September 3, 1975. A broad iron line feature is observed in the normal high state spectrum. The line equivalent width is given along with its full-width-half-maximum energy. Iron line fluorescence from an opaque, cool shell of material at the Alfven surface provides the necessary luminosity in this feature. The line energy width can be due to Doppler broadening if the shell is forced to corotate with the pulsar at a radius 800 million cm. Implications of this model regarding physical conditions near Her X-1 are discussed.

  18. Emission Line Spectra in the Soft X-ray Region 20 - 75 Angstroms

    Science.gov (United States)

    Lepson, J. K.; Beiersdorfer, P.; Chen, H.; Behar, E.; Kahn, S. M.

    2002-01-01

    As part of a project to complete a comprehensive catalogue of astrophysically relevant emission lines in support of new-generation X-ray observatories using the Lawrence Livermore electron beam ion traps EBIT-I and EDIT-II, emission lines of argon and sulfur in the soft X-ray and extreme ultraviolet region were studied. Observations of Ar IX through Ar XVI and S VII through S XIV between 20 and 75 Angstrom are presented to illustrate our work.

  19. The evolution of HI and CIV quasar absorption line systems at 1.9 < z < 3.2

    OpenAIRE

    Kim, Tae-Sun; Partl, Adrian M.; Carswell, Robert F.; Müller, Volker

    2013-01-01

    We have investigated the distribution and evolution of ~3100 intergalactic HI absorbers with HI column densities log N(HI) = [12.75, 17.0] at 1.9 < z < 3.2, using 18 high resolution, high S/N quasar spectra obtained from the ESO VLT/UVES archive. We used two sets of Voigt profile fitting analysis, one including all the available high-order Lyman lines to obtain reliable HI column densities of saturated lines, and another using only the Ly-alpha lines. There is no significant difference betwee...

  20. Two-photon-absorption line strengths for nitric oxide: Comparison of theory and sub-Doppler, laser-induced fluorescence measurements

    Science.gov (United States)

    Kulatilaka, Waruna D.; Lucht, Robert P.

    2017-03-01

    We discuss the results of high-resolution, sub-Doppler two-photon-absorption laser-induced fluorescence (TPALIF) spectroscopy of nitric oxide at low pressure and room temperature. The measurements were performed using the single-longitudinal mode output of a diode-laser-seeded optical parametric generator (OPG) system with a measured frequency bandwidth of 220 MHz. The measurements were performed using a counter-propagating pump beam geometry, resulting in sub-Doppler TPALIF spectra of NO for various rotational transitions in the (0,0) vibrational band of the A2Σ+ - X2Π electronic transition. The experimental results are compared with the results of a perturbative treatment of the rotational line strengths for the 20 different rotational branches of the X2Π(v″ = 0) → A2Σ+(v' = 0) two-photon absorption band. In the derivation of the expressions for the two-photon transition absorption strength, the closure relation is used for rotational states in the intermediate levels of the two-photon transition in analogy with the Placzek treatment of Raman transitions. The theoretical treatment of the effect of angular momentum coupling on the two-photon rotational line strengths features the use of irreducible spherical tensors and 3j symbols. The final results are expressed in terms of the Hund's case (a) coupling coefficients aJ and bJ for the X2Π(v″ = 0) rotational level wavefunctions, which are intermediate between Hund's case (a) and case (b). Considerable physical insight is provided by this final form of the equations for the rotational line strengths. Corrections to the two-photon absorption rotational line strength for higher order effects such as centrifugal stretching can be included in a straightforward fashion in the analysis by incorporating higher order terms in these coupling coefficients aJ and bJ, although these corrections are essentially negligible for J satellite transitions are in excellent agreement with our experimental measurements.

  1. Measurements of Narrow Mg II Associated Absorption Doublets with ...

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... The measurement of the variations of absorption lines over time is a good method to study the physical conditions of absorbers. In this paper, we measure the variations of the line strength of 36 narrow Mg II2796, 2803 associated absorption doublets, which are imprinted on 31 quasar spectra with two ...

  2. The absorption spectrum of acetylene near 1 μm (9280-10740 cm-1) (I): Line positions

    Science.gov (United States)

    Lyulin, O. M.; Béguier, S.; Hu, S. M.; Campargue, A.

    2018-03-01

    The high-resolution absorption spectrum of acetylene is studied by Fourier-transform spectroscopy (FTS) in the 9280-10740 cm-1 region dominated by the 3ν3 band near 9640 cm-1. Line positions and intensities of 1899 12C2H2 and 151 12C13CH2 absorption lines are retrieved from a spectrum recorded at room temperature (298.5 K) with a pressure of 87.6 hPa and a path length of 105 m. The measured 12C2H2 lines belong to thirty-three bands, twelve of them being newly assigned. The lines of 12C13CH2 in normal abundance (2.2%) belong to seven bands. For comparison the HITRAN database in the same region includes 301 lines of four 12C2H2 bands. Spectroscopic parameters of the upper vibrational levels are derived from band-by-band fits of the line positions (typical rms values are on the order of 0.002 cm-1). The comparison to the HITRAN line list and to results obtained using the global effective operator approach reveals a number of significant deviations. The occurrence of local rovibrational perturbations affecting a number of the analyzed bands is illustrated by the case of the strong 3ν3 band.

  3. Temperature measurement of burning aluminum powder based on the double line method of atomic emission spectra

    Science.gov (United States)

    Tang, Huijuan; Hao, Xiaojian; Hu, Xiaotao

    2018-01-01

    In the case of conventional contact temperature measurement, there is a delay phenomenon and high temperature resistant materials limitation. By using the faster response speed and theoretically no upper limit of the non-contact temperature method, the measurement system based on the principle of double line atomic emission spectroscopy temperature measurement is put forward, the structure and theory of temperature measuring device are introduced. According to the atomic spectrum database (ASD), Aluminum(Al) I 690.6 nm and Al I 708.5 nm are selected as the two lines in the temperature measurement. The intensity ratio of the two emission lines was measured by a spectrometer to obtain the temperature of Al burning in pure oxygen, and the result compared to the temperature measured by the thermocouple. It turns out that the temperature correlation between the two methods is good, and it proves the feasibility of the method.

  4. Faint emission features in the Mg II resonance-line wings. [in solar spectra

    Science.gov (United States)

    Allen, M. S.; Mcallister, H. C.

    1977-01-01

    Data obtained with a rocket-borne echelle spectrograph are presented which indicate the presence of three faint emission features deep in the cores of the Mg II h and k resonance-line wings in the solar Fraunhofer spectrum. Results of wavelength measurements are discussed, and the relative intensities of the emission features are examined. It is tentatively suggested that the first feature be identified with the Fe II line at 2797.037 A, the second feature is probably the V II line at 2803.469 A, and the third feature may originate in Fe II emission at 2804.021 A. Possible emission mechanisms are proposed, and it is concluded that the detected features may be of potential diagnostic value for the analysis of depth variations of temperature and velocity in the lower chromosphere as well as for solar and possibly stellar spectroscopy.

  5. Noninvasive monitoring of glucose concentration using differential absorption low-coherence interferometry based on rapid scanning optical delay line

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Yong; Zeng Nan; He Yonghong, E-mail: heyh@sz.tsinghua.edu.cn [Laboratory of Optical Imaging and Sensing, Graduate School at Shenzhen, Tsinghua University, Shenzhen, 518055 (China)

    2011-01-01

    A non-invasive method of detecting glucose concentration using differential absorption low-coherence interferometry (DALCI) based on rapid scanning optical delay line is presented. Two light sources, one centered within (1625 nm) a glucose absorption band, while the other outside (1310 nm) the glucose absorption band, are used in the experiment. The low-coherence interferometry (LCI) is employed to obtain the signals back-reflecting from the iris which carries the messages of material concentration in anterior chamber. Using rapid scanning optical delay line (RSOD) as the reference arm, we can detect the signals in a very short time. Therefore the glucose concentration can be monitored in real-time, which is very important for the detection in vivo. In our experiments, the cornea and aqueous humor can be treated as nearly non-scattering substance. The difference in the absorption coefficient is much larger than the difference in the scattering coefficient, so the influence of scattering can be neglected. By subtracting the algorithmic low-coherence interference signals of the two wavelengths, the absorption coefficient can be calculated which is proportional to glucose concentration. To reduce the speckle noise, a 30 variation of signals were used before the final calculation of the glucose concentration. The improvements of our experiment are also discussed in the article. The method has a potential application for noninvasive detection of glucose concentration in vivo and in real-time.

  6. Theoretical emission line ratios for [Fe III] and [Fe VII] applicable to the optical and infrared spectra of gaseous nebulae.

    Science.gov (United States)

    Keenan, F P; Aller, L H; Ryans, R S; Hyung, S

    2001-08-14

    Recent calculations of electron impact excitation rates and Einstein A-coefficients for transitions among the 3d(6) levels of Fe III and among the 3d(2) levels of Fe VII are used to derive theoretical emission line ratios applicable to the optical and infrared spectra of gaseous nebulae. Results for [Fe III] are generated for electron temperatures T(e) = 7,000-20,000 K and densities N(e) = 10(2)-10(8) cm(-3), whereas those for [Fe VII] are provided for T(e) = 10,000-30,000 K and N(e) = 10(2)-10(8) cm(-3). The theoretical line ratios are significantly different in some instances from earlier calculations and resolve discrepancies between theory and observation found for the planetary nebulae IC 4997 and NGC 7027.

  7. Absorption and fluorescence spectra of Am{sup 3+}-doped Cs{sub 2}NaLuCl{sub 6} elpasolite crystals

    Energy Technology Data Exchange (ETDEWEB)

    Barbanel`, Yu.A.; Chudnovskaya, G.P.; Dushin, R.B.; Kolin, V.V.; Kotlin, V.P.; Nekhoroshkov, S.N.; Pen`kin, M.V. [Radievyj Inst., St. Petersburg (Russian Federation)

    1998-07-24

    Low-temperature absorption and fluorescence (including self-fluorescence) spectra of Am{sup 3+} in the elpasolite lattice have been studied in the regions of the {sup 7}F{sub 6}<-{sup 7}F{sub 0} and {sup 5}L{sub 6}{yields}{sup 7}F{sub 0} transitions, correspondingly. Ten crystal field sublevels in the {sup 7}F{sub 6} and {sup 5}L{sub 6} levels have been localized and assigned. The crystal field parameters have been calculated for the AmCl{sub 6}{sup 3-} complex. (orig.) 17 refs.

  8. Emission lines of [K V] in the optical spectra of gaseous nebulae.

    Science.gov (United States)

    Keenan, Francis P; Aller, Lawrence H; Espey, Brian R; Exter, Katrina M; Hyung, Siek; Keenan, Michael T C; Pollacco, Don L; Ryans, Robert S I

    2002-04-02

    Recent R-matrix calculations of electron impact excitation rates in K v are used to derive the nebular emission line ratio R = I(4122.6 A)/I(4163.3 A) as a function of electron density (N(e)). This ratio is found to be very sensitive to changes in N(e) over the density range 10(3) to 10(6) cm(-3), but does not vary significantly with electron temperature, and hence in principle should provide an excellent optical N(e) diagnostic for the high-excitation zones of nebulae. The observed value of R for the planetary nebula NGC 7027, measured from a spectrum obtained with the Hamilton Echelle spectrograph on the 3-m Shane Telescope, implies a density in excellent agreement with that derived from [Ne iv], formed in the same region of the nebula as [K v]. This observation provides observational support for the accuracy of the theoretical [K v] line ratios, and hence the atomic data on which they are based. However, the analysis of a high-resolution spectrum of the symbiotic star RR Telescopii, obtained with the University College London Echelle Spectrograph on the 3.9-m Anglo-Australian Telescope, reveals that the [K v] 4122.6 A line in this object is badly blended with Fe ii 4122.6 A. Hence, the [K v] diagnostic may not be used for astrophysical sources that show a strong Fe ii emission line spectrum.

  9. Optical Absorption Spectra and Electronic Properties of Symmetric and Asymmetric Squaraine Dyes for Use in DSSC Solar Cells: DFT and TD-DFT Studies

    Directory of Open Access Journals (Sweden)

    Reda M. El-Shishtawy

    2016-04-01

    Full Text Available The electronic absorption spectra, ground-state geometries and electronic structures of symmetric and asymmetric squaraine dyes (SQD1–SQD4 were investigated using density functional theory (DFT and time-dependent (TD-DFT density functional theory at the B3LYP/6-311++G** level. The calculated ground-state geometries reveal pronounced conjugation in these dyes. Long-range corrected time dependent density functionals Perdew, Burke and Ernzerhof (PBE, PBE1PBE (PBE0, and the exchange functional of Tao, Perdew, Staroverov, and Scuseria (TPSSh with 6-311++G** basis set were employed to examine optical absorption properties. In an extensive comparison between the optical data and DFT benchmark calculations, the BEP functional with 6-311++G** basis set was found to be the most appropriate in describing the electronic absorption spectra. The calculated energy values of lowest unoccupied molecular orbitals (LUMO were 3.41, 3.19, 3.38 and 3.23 eV for SQD1, SQD2, SQD3, and SQD4, respectively. These values lie above the LUMO energy (−4.26 eV of the conduction band of TiO2 nanoparticles indicating possible electron injection from the excited dyes to the conduction band of the TiO2 in dye-sensitized solar cells (DSSCs. Also, aromaticity computation for these dyes are in good agreement with the data obtained optically and geometrically with SQD4 as the highest aromatic structure. Based on the optimized molecular geometries, relative positions of the frontier orbitals, and the absorption maxima, we propose that these dyes are suitable components of photovoltaic DSSC devices.

  10. Optical Absorption Spectra and Electronic Properties of Symmetric and Asymmetric Squaraine Dyes for Use in DSSC Solar Cells: DFT and TD-DFT Studies.

    Science.gov (United States)

    El-Shishtawy, Reda M; Elroby, Shaaban A; Asiri, Abdullah M; Müllen, Klaus

    2016-04-01

    The electronic absorption spectra, ground-state geometries and electronic structures of symmetric and asymmetric squaraine dyes (SQD1-SQD4) were investigated using density functional theory (DFT) and time-dependent (TD-DFT) density functional theory at the B3LYP/6-311++G** level. The calculated ground-state geometries reveal pronounced conjugation in these dyes. Long-range corrected time dependent density functionals Perdew, Burke and Ernzerhof (PBE, PBE1PBE (PBE0)), and the exchange functional of Tao, Perdew, Staroverov, and Scuseria (TPSSh) with 6-311++G** basis set were employed to examine optical absorption properties. In an extensive comparison between the optical data and DFT benchmark calculations, the BEP functional with 6-311++G** basis set was found to be the most appropriate in describing the electronic absorption spectra. The calculated energy values of lowest unoccupied molecular orbitals (LUMO) were 3.41, 3.19, 3.38 and 3.23 eV for SQD1, SQD2, SQD3, and SQD4, respectively. These values lie above the LUMO energy (-4.26 eV) of the conduction band of TiO₂ nanoparticles indicating possible electron injection from the excited dyes to the conduction band of the TiO₂ in dye-sensitized solar cells (DSSCs). Also, aromaticity computation for these dyes are in good agreement with the data obtained optically and geometrically with SQD4 as the highest aromatic structure. Based on the optimized molecular geometries, relative positions of the frontier orbitals, and the absorption maxima, we propose that these dyes are suitable components of photovoltaic DSSC devices.

  11. Infrared Spectroscopy of CO Ro-vibrational Absorption Lines toward the Obscured AGN IRAS 08572+3915

    OpenAIRE

    Shirahata, Mai; Nakagawa, Takao; Usuda, Tomonori; Goto, Miwa; Suto, Hiroshi; Geballe, T. R.

    2012-01-01

    We present high-resolution spectroscopy of gaseous CO absorption in the fundamental ro-vibrational band toward the heavily obscured active galactic nucleus (AGN) IRAS 08572+3915. We have detected absorption lines up to highly excited rotational levels (J 200 km s-1) of which is due to blueshifted (-160 km s-1) gas at a temperature of ~ 270 K absorbing at velocities as high as -400 km s-1. A much weaker but even warmer (~ 700 K) component, which is highly redshifted (+100 km s-1), is also dete...

  12. First-principles calculation of optical absorption spectra in conjugated polymers: Role of electron-hole interaction

    Energy Technology Data Exchange (ETDEWEB)

    Rohlfing, Michael; Tiago, M.L.; Louie, Steven G.

    2000-03-20

    Experimental and theoretical studies have shown that excitonic effects play an important role in the optical properties of conjugated polymers. The optical absorption spectrum of trans-polyacetylene, for example, can be understood as completely dominated by the formation of exciton bound states. We review a recently developed first-principles method for computing the excitonic effects and optical spectrum, with no adjustable parameters. This theory is used to study the absorption spectrum of two conjugated polymers: trans-polyacetylene and poly-phenylene-vinylene(PPV).

  13. A multiwavelength continuum characterization of high-redshift broad absorption line quasars

    Science.gov (United States)

    Tuccillo, D.; Bruni, G.; DiPompeo, M. A.; Brotherton, M. S.; Pasetto, A.; Kraus, A.; González-Serrano, J. I.; Mack, K.-H.

    2017-06-01

    We present the results of a multiwavelength study of a sample of high-redshift radio-loud (RL) broad absorption line (BAL) quasars. This way, we extend to higher redshift previous studies on the radio properties and broad-band optical colours of these objects. We have selected a sample of 22 RL BAL quasars with 3.6 ≤ z ≤ 4.8 cross-correlating the FIRST radio survey with the Sloan Digital Sky Survey (SDSS). Flux densities between 1.25 and 9.5 GHz have been collected with the Jansky Very Large Array and Effelsberg-100 m telescopes for 15 BAL and 14 non-BAL quasars used as a comparison sample. We determine the synchrotron peak frequency, constraining their age. A large number of gigahertz peaked spectrum and high-frequency peakers sources have been found in both samples (80 per cent for BAL and 71 per cent for non-BAL quasars), not suggesting a younger age for BAL quasars. The spectral index distribution provides information about the orientation of these sources, and we find statistically similar distributions for the BAL and non-BAL quasars in contrast to work done on lower redshift samples. Our sample may be too small to convincingly find the same effect, or might represent a real evolutionary effect based on the large fraction of young sources. We also study the properties of broad-band colours in both optical (SDSS) and near- and mid-infrared (UK Infrared Telescope Deep Sky Survey and Wide-field Infrared Survey Explorer - WISE) bands, finding that also at high-redshift BAL quasars tend to be optically redder than non-BAL quasars. However, these differences are no more evident at longer wavelength, when comparing colours of the two samples by mean of the WISE survey.

  14. Interpretation of polarized Cu K x-ray absorption near-edge-structure spectra of CuO

    Czech Academy of Sciences Publication Activity Database

    Šipr, Ondřej; Šimůnek, Antonín

    2001-01-01

    Roč. 13, - (2001), s. 8519-8525 ISSN 0953-8984 Institutional research plan: CEZ:AV0Z1010914 Keywords : polarized Cu K-edge spectra * CuO * band-structure calculations Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.611, year: 2001

  15. In-Line Monitoring of a High-Shear Granulation Process Using the Baseline Shift of Near Infrared Spectra.

    Science.gov (United States)

    Kuriyama, Atsushi; Osuga, Jin; Hattori, Yusuke; Otsuka, Makoto

    2018-02-01

    Although near infrared (NIR) spectra are primarily influenced by undesired variations, i.e., baseline shifts and non-linearity, and many applications of NIR spectroscopy to the real-time monitoring of wet granulation processes have been reported, the granulation mechanisms behind these variations have not been fully discussed. These variations of NIR spectra can be canceled out using appropriate pre-processing techniques prior to spectral analysis. The present study assessed the feasibility of directly using baseline shifts in NIR spectra to monitor granulation processes, because such shifts can reflect changes in the physical properties of the granular material, including particle size, shape, density, and refractive index. Specifically, OPUSGRAN ® , a novel granulation technology, was investigated by in-line NIR monitoring. NIR spectra were collected using a NIR diffuse reflectance fiber optic probe immersed in a high-shear granulator while simultaneously examining the morphology, particle size, density, strength, and Raman images of the mixture during granulation. The NIR baseline shift pattern was found to be characteristic of the OPUSGRAN ® technology and was attributed to variations in the light transmittance, reflection, and scattering resulting from changes in the physicochemical properties of the samples during granulation. The baseline shift also exhibited an inflection point around the completion of granulation, and therefore may be used to determine the endpoint of the process. These results suggest that a specific pattern of NIR baseline shifts are associated with the unique OPUSGRAN ® granulation mechanism and can be applied to monitor the manufacturing process and determine the endpoint.

  16. Accurate Theoretical Methane Line Lists in the Infrared up to 3000 K and Quasi-continuum Absorption/Emission Modeling for Astrophysical Applications

    Energy Technology Data Exchange (ETDEWEB)

    Rey, Michael; Tyuterev, Vladimir G. [Groupe de Spectrométrie Moléculaire et Atmosphérique, UMR CNRS 7331, BP 1039, F-51687, Reims Cedex 2 (France); Nikitin, Andrei V., E-mail: michael.rey@univ-reims.fr [Laboratory of Theoretical Spectroscopy, Institute of Atmospheric Optics, SB RAS, 634055 Tomsk (Russian Federation)

    2017-10-01

    Modeling atmospheres of hot exoplanets and brown dwarfs requires high- T databases that include methane as the major hydrocarbon. We report a complete theoretical line list of {sup 12}CH{sub 4} in the infrared range 0–13,400 cm{sup −1} up to T {sub max} = 3000 K computed via a full quantum-mechanical method from ab initio potential energy and dipole moment surfaces. Over 150 billion transitions were generated with the lower rovibrational energy cutoff 33,000 cm{sup −1} and intensity cutoff down to 10{sup −33} cm/molecule to ensure convergent opacity predictions. Empirical corrections for 3.7 million of the strongest transitions permitted line position accuracies of 0.001–0.01 cm{sup −1}. Full data are partitioned into two sets. “Light lists” contain strong and medium transitions necessary for an accurate description of sharp features in absorption/emission spectra. For a fast and efficient modeling of quasi-continuum cross sections, billions of tiny lines are compressed in “super-line” libraries according to Rey et al. These combined data will be freely accessible via the TheoReTS information system (http://theorets.univ-reims.fr, http://theorets.tsu.ru), which provides a user-friendly interface for simulations of absorption coefficients, cross-sectional transmittance, and radiance. Comparisons with cold, room, and high- T experimental data show that the data reported here represent the first global theoretical methane lists suitable for high-resolution astrophysical applications.

  17. Determination of self-absorption in emission lines from some optically thick plasmas

    International Nuclear Information System (INIS)

    Pianarosa, P.; Gagne, J.M.; Larin, G.; Saint-Dizier, J.P.

    1982-01-01

    We present a relatively simple method by which the amount of self-absorption in laboratory-produced plasmas can be evaluated. As an illustration we apply it here to the evaluation of self-absorption of a U I resonance transition from a hollow-cathode-generated plasma. The method can be generalized to include more-complex situations

  18. Second and third peaks in the non-resonant microwave absorption spectra of superconducting Bi2212 crystals

    CSIR Research Space (South Africa)

    Srinivasu, V V

    2010-04-01

    Full Text Available Non-resonant microwave absorption (NMA) measurements at liquid nitrogen temperature with systematic microwave power variation showed a two-peak structure in the Bi-2212 textured crystals, similar to that observed in the Bi-2212 single crystals...

  19. Forward modeling and retrieval of water vapor from the Global Ozone Monitoring Experiment: Treatment of narrowband absorption spectra

    NARCIS (Netherlands)

    Lang, R.; Maurellis, A.N.; van der Zande, W.J.; Aben, I.; Landgraf, J.; Ubachs, W.M.G.

    2002-01-01

    [1] We present the algorithm and results for a new fast forward modeling technique applied to the retrieval of atmospheric water vapor from satellite measurements using a weak ro-vibrational overtone band in the visible. The algorithm uses an Optical Absorption Coefficient Spectroscopy (OACS) method

  20. STRONG MAGNETIC-X-RAY DICHROISM IN 2P ABSORPTION-SPECTRA OF 3D TRANSITION-METAL IONS

    NARCIS (Netherlands)

    VANDERLAAN, G; THOLE, BT

    1991-01-01

    From atomic calculations in crystal-field symmetry we find a very strong circular and linear dichroism in the 2p x-ray absorption edges of magnetically ordered 3d transition-metal ions. The spectral shape changes drastically with the character of the ground state, which is determined by the presence

  1. Ab initio calculation of UV-absorption spectra of chlorophyll a: Comparison study between RHF/CIS, TDDFT, and semi-empirical methods

    Directory of Open Access Journals (Sweden)

    Veinardi Suendo

    2012-07-01

    Full Text Available Chlorophyll a is one the most abundant pigment on Earth that responsible for trapping the light energy to perform photosynthesis in green plants. This molecule has been studied for many years from different point of views in both experimental and theoretical interests. In this study, the restricted Hartree-Fock configuration interaction single (RHF/CIS, time-dependent density functional theory (TDDFT and several semi-empirical methods (CNDO/s and ZINDO calculations were carried out to reconstruct the UV-Vis absorption spectra of chlorophyll a. In some extend, the calculation results based on single molecule approach were succeeded to reconstruct the absorption spectra but required to be rescaled to fit the experimental one. In general, the semi-empirical methods provide better energy scaling factor that closer to unity. However, they lack of vertical transition fine features with respect to the spectrum obtained experimentally. Here, the ab initio calculations provide more complete features, especially the TDDFT at high level of basis sets that also has a good accuracy in the transition energies. The contribution of ground states and excited states orbitals in the main vertical transitions is discussed based on delocalization nature of the wavefunctions and the presence of solvent through polarizable continuum model (PCM.

  2. Solvatochromic effect in absorption and emission spectra of star-shaped bipolar derivatives of 1,3,5-triazine and carbazole. A time-dependent density functional study.

    Science.gov (United States)

    Baryshnikov, Gleb V; Bondarchuk, Sergey V; Minaeva, Valentina A; Ågren, Hans; Minaev, Boris F

    2017-02-01

    A series of three star-shaped compounds containing both donor (carbazole) and acceptor (2,4,6-triphenyl-1,3,5-triazine) moieties linked through various linking bridges was studied theoretically at the linear response TD-DFT level of theory to describe their absorption and fluorescence spectra. The concept of a localized charge-transfer excited state has been applied successfully to explain the observed strong solvatochromic effect in the emission spectra of the studied molecules, which can be utilized for the fabrication of color tunable solution-processable OLEDs. The concept is in particularly applicable to donor-acceptor species with a C 3 symmetry point group where the static dipole moment changes dramatically upon electronic excitation. An important peculiarity of the studied molecules is that they are characterized by non-zero values of the HOMO and LUMO orbitals in the same common part of molecular space that provides a large electric dipole transition moment for both light absorption and emission. Graphical abstract Star-shaped C 3 symmetry point group derivatives for color tunable OLEDs.

  3. Non-LTE Analysis of Interstellar Line Spectra of SiO

    Science.gov (United States)

    Zhang, Ziwei; Stancil, Phillip C.

    2016-01-01

    SiO emission lines are important probes of chemical processes in diverse astrophysical environments. In circumstellar outflows of AGB stars, the production of silicate grains is preceded by SiO formation, making SiO a useful measure of Si depletion. SiO is also commonly observed in shocks associated with the outflows of young stellar objects, both low- and high-mass. To model SiO emission for non-LTE conditions requires collisional rate coefficients due to H2 impact which are currently unavailable. Unknown collisional rate coefficients are often estimated from known systems. For the case of SiO-H2, rate coefficients have previously been adapted from a different collider, He (Dayau & Balanca 2006), based on a reduced-mass scaling approach. Recently it has been suggested that scaling via the interaction potential well depth and the reduced masses of the collisional systems may be more reliable (Walker et al. 2014). Using the non-LTE spectral modeling package Radex (van der Tak et al. 2007), we construct diagnostic plots of SiO line ratios using SiO-H2 collisional rate coefficients based on (i) reduced-mass scaling from the LAMDA database, (ii) potential well-depth scaling, and (iii) a more comprehensive input with multiple colliders (H2, He and H). Our goal is to give a more rigorous approach to SiO line emission simulations to better understand Si chemistry, dust formation/destruction, and other astrophysical processes.This work was supported by NASA ATP grant NNX15AI61G.

  4. A multi-epoch spectroscopic study of the BAL quasar APM 08279+5255. II. Emission- and absorption-line variability time lags

    Science.gov (United States)

    Saturni, F. G.; Trevese, D.; Vagnetti, F.; Perna, M.; Dadina, M.

    2016-03-01

    Context. The study of high-redshift bright quasars is crucial to gather information about the history of galaxy assembly and evolution. Variability analyses can provide useful data on the physics of quasar processes and their relation with the host galaxy. Aims: In this study, we aim to measure the black hole mass of the bright lensed BAL QSO APM 08279+5255 at z = 3.911 through reverberation mapping, and to update and extend the monitoring of its C IV absorption line variability. Methods: We perform the first reverberation mapping of the Si IV and C IV emission lines for a high-luminosity quasar at high redshift with the use of 138 R-band photometric data and 30 spectra available over 16 years of observations. We also cross-correlate the C IV absorption equivalent width variations with the continuum light curve to estimate the recombination time lags of the various absorbers and infer the physical conditions of the ionised gas. Results: We find a reverberation-mapping time lag of ~900 rest-frame days for both Si IV and C IV emission lines. This is consistent with an extension of the BLR size-to-luminosity relation for active galactic nuclei up to a luminosity of ~1048 erg s-1, and implies a black hole mass of 1010 M⊙. Additionally, we measure a recombination time lag of ~160 days in the rest frame for the C IV narrow absorption system, which implies an electron density of the absorbing gas of ~2.5 × 104 cm-3. Conclusions: The measured black hole mass of APM 08279+5255 indicates that the quasar resides in an under-massive host-galaxy bulge with Mbulge ~ 7.5MBH, and that the lens magnification is lower than ~8. Finally, the inferred electron density of the narrow-line absorber implies a distance of the order of 10 kpc of the absorbing gas from the quasar, placing it within the host galaxy.

  5. Absorption and Reflectance Spectra of Microwave Radiation by an Epoxy Resin Composite with Multi-Walled Carbon Nanotubes

    Science.gov (United States)

    Komarov, F. F.; Milchanin, O. V.; Parfimovich, I. D.; Grinchenko, M. V.; Parhomenko, I. N.; Tkachev, A. G.; Bychanok, D. S.

    2017-09-01

    A procedure for dispersing multi-walled carbon nanotubes in the two-component polymer SpeciFix-20 (epoxy resin + hardener) using combined hydromechanical and ultrasonic mixing was developed. New composites with carbon nanotubes were produced. Their structures and optical and electrophysical characteristics were studied. The propagation of microwave radiation (26-38 GHz) in experimental composite samples was investigated. It was shown that the strong absorption of the composites appeared only with significant additions of multi-walled carbon nanotubes and was caused by the resulting electrical conductivity of the composites. A size effect of the additive on the optical characteristics of the produced composites was established. Equal absorption coefficients for microwave radiation could be achieved by using a smaller amount of carbon nanotubes with smaller diameters and greater specific surface areas in the composite.

  6. Effect of photoelectric fluorescence on the formation of x-ray absorption lines in laser-plasma experiments

    International Nuclear Information System (INIS)

    Epstein, R.; Yaakobi, B.

    1991-01-01

    In laser-plasma experiments, conditions in an embedded layer in a target shell can be inferred from the spectral attenuation of x-ray continuum radiation by the layer [B. Yaakobi et al., Opt. Commun. 34, 213 (1980)]. In such experiments, absorption lines are formed by 1s-2p absorption transitions in heliumlike through fluorinelike species of certain ions in the layer to be diagnosed. The areal density of each species can be inferred from the attenuation in the spectrum within its respective band, provided the average 1s-2p absorption cross sections for each species are known and provided competing line-forming mechanisms are taken into account. In photoelectric fluorescence, which is one such potentially important competing mechanism, the formation of a 1s vacancy by photoionization is followed by 2p-1s spontaneous emission within the same spectral range as the 1s-2p absorption band of the same ion. The importance of photoelectric fluorescence depends on the supply of ionizing photons, which is sensitive to the design of the experiment. This process should be considered when analyzing experiments where the continuum is hardened by high core temperatures, by opacity effects, or by core components that radiate efficiently at ionizing energies

  7. On-line Zeeman atomic-absorption spectroscopy for mercury analysis in oil-shale gases. Final report

    Energy Technology Data Exchange (ETDEWEB)

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

    1981-03-01

    This report describes an instrumental technique to continuously measure total mercury in gas streams on a real-time basis. The technique utilizes Zeeman atomic absorption spectroscopy (ZAA) for on-line measurement of mercury in the presence of smoke, organic vapors, and oil mist which are typically present in offgases from oil shale processing plants. The accuracy of the ZAA background correction technique enables analytical measurement of mercury with up to 95% attenuation of the 2537A analytical line by broadband uv absorption. Furnaces with optical absorption tubes of different lengths are used depending upon the mercury concentration. Between 5 and 250 ppB (nanomoles Hg/mole of gas) of mercury in an 18-cm furnace is used. The instrumental response with this furnace is characterized by a detection limit (DL) of 2 ppB, a linear response up to 100 ppB, and a precision of +- 7% or better. In the 50 ppB to 1.6 ppM range, a furnace with a 5-cm optical absorption tube yields a DL of 10 ppB, a linear response up to 800 ppB, and a precision of +- 10% or better. Sample gas flow rates can be varied between 400 and 4000 scc/min for either furnace. 35 figures, 3 tables.

  8. Tailored pump-probe transient spectroscopy with time-dependent density-functional theory: controlling absorption spectra

    Science.gov (United States)

    Walkenhorst, Jessica; De Giovannini, Umberto; Castro, Alberto; Rubio, Angel

    2016-05-01

    Recent advances in laser technology allow us to follow electronic motion at its natural time-scale with ultra-fast time resolution, leading the way towards attosecond physics experiments of extreme precision. In this work, we assess the use of tailored pumps in order to enhance (or reduce) some given features of the probe absorption (for example, absorption in the visible range of otherwise transparent samples). This type of manipulation of the system response could be helpful for its full characterization, since it would allow us to visualize transitions that are dark when using unshaped pulses. In order to investigate these possibilities, we perform first a theoretical analysis of the non-equilibrium response function in this context, aided by one simple numerical model of the hydrogen atom. Then, we proceed to investigate the feasibility of using time-dependent density-functional theory as a means to implement, theoretically, this absorption-optimization idea, for more complex atoms or molecules. We conclude that the proposed idea could in principle be brought to the laboratory: tailored pump pulses can excite systems into light-absorbing states. However, we also highlight the severe numerical and theoretical difficulties posed by the problem: large-scale non-equilibrium quantum dynamics are cumbersome, even with TDDFT, and the shortcomings of state-of-the-art TDDFT functionals may still be serious for these out-of-equilibrium situations.

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

    International Nuclear Information System (INIS)

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

    2016-01-01

    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, N 2 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.

  10. Higher‐order mode absorption measurement of X-band choke-mode cavities in a radial line structure

    Energy Technology Data Exchange (ETDEWEB)

    Zha, Hao [Department of Engineering Physics, Tsinghua University, Beijing CN-100086 (China); Key Laboratory of Particle and Radiation Imaging, Tsinghua University, Ministry of Education, Beijing (China); The European Organization for Nuclear Research, Geneva CH-1211 (Switzerland); Shi, Jiaru, E-mail: shij@mail.tsinghua.edu.cn [Department of Engineering Physics, Tsinghua University, Beijing CN-100086 (China); Key Laboratory of Particle and Radiation Imaging, Tsinghua University, Ministry of Education, Beijing (China); The European Organization for Nuclear Research, Geneva CH-1211 (Switzerland); Wu, Xiaowei; Chen, Huaibi [Department of Engineering Physics, Tsinghua University, Beijing CN-100086 (China); Key Laboratory of Particle and Radiation Imaging, Tsinghua University, Ministry of Education, Beijing (China)

    2016-04-01

    An experiment is presented to study the higher-order mode (HOM) suppression of X-band choke-mode structures with a vector network analyzer (VNA). Specific radial line disks were built to test the reflection from the corresponding damping load and different choke geometries. The mismatch between the radial lines and the VNA was calibrated through a special multi-short-load calibration method. The measured reflections of different choke geometries showed good agreement with the theoretical calculations and verified the HOM absorption feature of each geometric design.

  11. Higher-order mode absorption measurement of X-band choke-mode cavities in a radial line structure

    Science.gov (United States)

    Zha, Hao; Shi, Jiaru; Wu, Xiaowei; Chen, Huaibi

    2016-04-01

    An experiment is presented to study the higher-order mode (HOM) suppression of X-band choke-mode structures with a vector network analyzer (VNA). Specific radial line disks were built to test the reflection from the corresponding damping load and different choke geometries. The mismatch between the radial lines and the VNA was calibrated through a special multi-short-load calibration method. The measured reflections of different choke geometries showed good agreement with the theoretical calculations and verified the HOM absorption feature of each geometric design.

  12. Estimation of Mass-Loss Rates from Emission Line Profiles in the UV Spectra of Cool Stars

    Science.gov (United States)

    Carpenter, K. G.; Robinson, R. D.; Harper, G. M.

    1999-01-01

    The photon-scattering winds of cool, low-gravity stars (K-M giants and supergiants) produce absorption features in the strong chromospheric emission lines. This provides us with an opportunity to assess important parameters of the wind, including flow and turbulent velocities, the optical depth of the wind above the region of photon creation, and the star's mass-loss rate. We have used the Lamers et al. Sobolev with Exact Integration (SEI) radiative transfer code along with simple models of the outer atmospheric structure to compute synthetic line profiles for comparison with the observed line profiles. The SEI code has the advantage of being computationally fast and allows a great number of possible wind models to be examined. We therefore use it here to obtain initial first-order estimates of the wind parameters. More sophisticated, but more time-consuming and resource intensive calculations will be performed at a later date, using the SEI-deduced wind parameters as a starting point. A comparison of the profiles over a range of wind velocity laws, turbulence values, and line opacities allows us to constrain the wind parameters, and to estimate the mass-loss rates. We have applied this analysis technique (using lines of Mg II, 0 I, and Fe II) so far to four stars: the normal K5-giant alpha Tau, the hybrid K-giant gamma Dra, the K5 supergiant lambda Vel, and the M-giant gamma Cru. We present in this paper a description of the technique, including the assumptions which go into its use, an assessment of its robustness, and the results of our analysis.

  13. Determination of equilibrium structures of bromothymol blue revealed by using quantum chemistry with an aid of multivariate analysis of electronic absorption spectra

    Science.gov (United States)

    Shimada, Toru; Hasegawa, Takeshi

    2017-10-01

    The pH dependent chemical structures of bromothymol blue (BTB), which have long been under controversy, are determined by employing a combined technique of multivariate analysis of electronic absorption spectra and quantum chemistry. Principle component analysis (PCA) of the pH dependent spectra apparently reveals that only two chemical species are adequate to fully account for the color changes, with which the spectral decomposition is readily performed by using augmented alternative least-squares (ALS) regression analysis. The quantity variation by the ALS analysis also reveals the practical acid dissociation constant, pKa‧. The determination of pKa‧ is performed for various ionic strengths, which reveals the thermodynamic acid constant (pKa = 7.5) and the number of charge on each chemical species; the yellow form is negatively charged species of - 1 and the blue form that of - 2. On this chemical information, the quantum chemical calculation is carried out to find that BTB molecules take the pure quinoid form in an acid solution and the quinoid-phenolate form in an alkaline solution. The time-dependent density functional theory (TD-DFT) calculations for the theoretically determined chemical structures account for the peak shift of the electronic spectra. In this manner, the structures of all the chemical species appeared in equilibrium have finally been confirmed.

  14. Determination of equilibrium structures of bromothymol blue revealed by using quantum chemistry with an aid of multivariate analysis of electronic absorption spectra.

    Science.gov (United States)

    Shimada, Toru; Hasegawa, Takeshi

    2017-10-05

    The pH dependent chemical structures of bromothymol blue (BTB), which have long been under controversy, are determined by employing a combined technique of multivariate analysis of electronic absorption spectra and quantum chemistry. Principle component analysis (PCA) of the pH dependent spectra apparently reveals that only two chemical species are adequate to fully account for the color changes, with which the spectral decomposition is readily performed by using augmented alternative least-squares (ALS) regression analysis. The quantity variation by the ALS analysis also reveals the practical acid dissociation constant, pK a '. The determination of pK a ' is performed for various ionic strengths, which reveals the thermodynamic acid constant (pK a =7.5) and the number of charge on each chemical species; the yellow form is negatively charged species of -1 and the blue form that of -2. On this chemical information, the quantum chemical calculation is carried out to find that BTB molecules take the pure quinoid form in an acid solution and the quinoid-phenolate form in an alkaline solution. The time-dependent density functional theory (TD-DFT) calculations for the theoretically determined chemical structures account for the peak shift of the electronic spectra. In this manner, the structures of all the chemical species appeared in equilibrium have finally been confirmed. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Line-Broadening in Low-Temperature Solid-State NMR Spectra of Fibrils

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Thomas; Dotta, Claudio; Balacescu, Livia; Gath, Julia; Hunkeler, Andreas [ETH Zurich, Physical Chemistry (Switzerland); Böckmann, Anja, E-mail: a.bockmann@ibcp.fr [Université de Lyon 1, Institut de Biologie et Chimie des Protéines, UMR 5086 CNRS (France); Meier, Beat H., E-mail: beme@ethz.ch [ETH Zurich, Physical Chemistry (Switzerland)

    2017-01-15

    The temperature-dependent resonance-line broadening of HET-s(218–289) in its amyloid form is investigated in the range between 110 K and 280 K. Significant differences are observed between residues in the structured hydrophobic triangular core, which are broadened the least and can be detected down to 100 K, and in the solvent-exposed parts, which are broadened the most and often disappear from the observed spectrum around 200 K. Below the freezing of the bulk water, around 273 K, the protein fibrils are still surrounded by a layer of mobile water whose thickness decreases with temperature, leading to drying out of the fibrils.

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

    Science.gov (United States)

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

    2018-03-01

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

  17. The dependence of C IV broad absorption line properties on accompanying Si IV and Al III absorption: relating quasar-wind ionization levels, kinematics, and column densities

    Energy Technology Data Exchange (ETDEWEB)

    Filiz Ak, N.; Brandt, W. N.; Schneider, D. P.; Trump, J. R. [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States); Hall, P. B. [Department of Physics and Astronomy, York University, 4700 Keele Street, Toronto, Ontario M3J 1P3 (Canada); Anderson, S. F. [Astronomy Department, University of Washington, Seattle, WA 98195 (United States); Hamann, F. [Department of Astronomy, University of Florida, Gainesville, FL 32611-2055 (United States); Myers, Adam D. [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); Pâris, I. [Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago (Chile); Petitjean, P. [Institut d' Astrophysique de Paris, Universite Paris 6, F-75014 Paris (France); Ross, Nicholas P. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Shen, Yue [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); York, Don, E-mail: nfilizak@astro.psu.edu [Department of Astronomy and Astrophysics, The University of Chicago, Chicago, IL 60637 (United States)

    2014-08-20

    We consider how the profile and multi-year variability properties of a large sample of C IV Broad Absorption Line (BAL) troughs change when BALs from Si IV and/or Al III are present at corresponding velocities, indicating that the line of sight intercepts at least some lower ionization gas. We derive a number of observational results for C IV BALs separated according to the presence or absence of accompanying lower ionization transitions, including measurements of composite profile shapes, equivalent width (EW), characteristic velocities, composite variation profiles, and EW variability. We also measure the correlations between EW and fractional-EW variability for C IV, Si IV, and Al III. Our measurements reveal the basic correlated changes between ionization level, kinematics, and column density expected in accretion-disk wind models; e.g., lines of sight including lower ionization material generally show deeper and broader C IV troughs that have smaller minimum velocities and that are less variable. Many C IV BALs with no accompanying Si IV or Al III BALs may have only mild or no saturation.

  18. Off-line analysis of positron annihilation spectra. I. Signature of crystal symmetry

    International Nuclear Information System (INIS)

    Adam, Gh.; Adam, S.

    1997-01-01

    While the technique of 2-D angular correlation of the electron-positron annihilation radiation (2D-ACAR) yields data in the laboratory frame, consistent off-line data analysis requires their reformulation in the crystal frame. In the case of an n-axis projected 2D-ACAR spectrum (where n denotes a principal crystallographic axis) of a high-T c superconductor, the crystal frame derivation needs enhancement of information on spectrum symmetry. The concept of signature of crystal symmetry (SCS) in a 2D-ACAR histogram discussed in this paper is a basic ingredient to the consistent solution of the problem. The SCS in a row 2D-ACAR histogram is defined as a collection of chi-square sums over M max + 1 sets of sites inside the detector-defined histogram plane. The number M max is fixed by choice of the principal crystallographic axis n-vector and the angular aperture of the setup. The necessity of this concept is discussed in Section 2. The correct understanding of the meaning of the SCS results heavily relies of that of the various sources contributing to the symmetry a 2D-ACAR spectrum. This point is discussed in Section 3. The quantitative definition of the SCS is detailed in Section 4. Finally, Section 5 is devoted to a short consideration of the computation of the SCS numerical values

  19. IDEN2-A program for visual identification of spectral lines and energy levels in optical spectra of atoms and simple molecules

    Science.gov (United States)

    Azarov, V. I.; Kramida, A.; Vokhmentsev, M. Ya.

    2018-04-01

    The article describes a Java program that can be used in a user-friendly way to visually identify spectral lines observed in complex spectra with theoretically predicted transitions between atomic or molecular energy levels. The program arranges various information about spectral lines and energy levels in such a way that line identification and determination of positions of experimentally observed energy levels become much easier tasks that can be solved fast and efficiently.

  20. Experimental and theoretical correlations between vanadium K-edge X-ray absorption and Kβ emission spectra.

    Science.gov (United States)

    Rees, Julian A; Wandzilak, Aleksandra; Maganas, Dimitrios; Wurster, Nicole I C; Hugenbruch, Stefan; Kowalska, Joanna K; Pollock, Christopher J; Lima, Frederico A; Finkelstein, Kenneth D; DeBeer, Serena

    2016-09-01

    A series of vanadium compounds was studied by K-edge X-ray absorption (XAS) and K[Formula: see text] X-ray emission spectroscopies (XES). Qualitative trends within the datasets, as well as comparisons between the XAS and XES data, illustrate the information content of both methods. The complementary nature of the chemical insight highlights the success of this dual-technique approach in characterizing both the structural and electronic properties of vanadium sites. In particular, and in contrast to XAS or extended X-ray absorption fine structure (EXAFS), we demonstrate that valence-to-core XES is capable of differentiating between ligating atoms with the same identity but different bonding character. Finally, density functional theory (DFT) and time-dependent DFT calculations enable a more detailed, quantitative interpretation of the data. We also establish correction factors for the computational protocols through calibration to experiment. These hard X-ray methods can probe vanadium ions in any oxidation or spin state, and can readily be applied to sample environments ranging from solid-phase catalysts to biological samples in frozen solution. Thus, the combined XAS and XES approach, coupled with DFT calculations, provides a robust tool for the study of vanadium atoms in bioinorganic chemistry.

  1. Comparative analysis of the vibrational structure of the absorption spectra of acrolein in the excited ( S 1) electronic state

    Science.gov (United States)

    Koroleva, L. A.; Tyulin, V. I.; Matveev, V. K.; Pentin, Yu. A.

    2012-04-01

    The assignments of absorption bands of the vibrational structure of the UV spectrum are compared with the assignments of bands obtained by the CRDS method in a supersonic jet from the time of laser radiation damping for the trans isomer of acrolein in the excited ( S 1) electronic state. The ν00 trans = 25861 cm-1 values and fundamental frequencies, including torsional vibration frequency, obtained by the two methods were found to coincide in the excited electronic state ( S 1) for this isomer. The assignments of several absorption bands of the vibrational structure of the spectrum obtained by the CRDS method were changed. Changes in the assignment of (0-v') transition bands of the torsional vibration of the trans isomer in the Deslandres table from the ν00 trans trans origin allowed the table to be extended to high quantum numbers v'. The torsional vibration frequencies up to v' = 5 were found to be close to the frequencies found by analyzing the vibrational structure of the UV spectrum and calculated quantum-mechanically. The coincidence of the barrier to internal rotation (the cis-trans transition) in the one-dimensional model with that calculated quantum-mechanically using the two-dimensional model corresponds to a planar structure of the acrolein molecule in the excited ( S 1) electronic state.

  2. New accurate theoretical line lists of 12CH4 and 13CH4 in the 0-13400 cm-1 range: Application to the modeling of methane absorption in Titan's atmosphere

    Science.gov (United States)

    Rey, Michaël; Nikitin, Andrei V.; Bézard, Bruno; Rannou, Pascal; Coustenis, Athena; Tyuterev, Vladimir G.

    2018-03-01

    The spectrum of methane is very important for the analysis and modeling of Titan's atmosphere but its insufficient knowledge in the near infrared, with the absence of reliable absorption coefficients, is an important limitation. In order to help the astronomer community for analyzing high-quality spectra, we report in the present work the first accurate theoretical methane line lists (T = 50-350 K) of 12CH4 and 13CH4 up to 13400 cm-1 ( > 0.75 μm). These lists are built from extensive variational calculations using our recent ab initio potential and dipole moment surfaces and will be freely accessible via the TheoReTS information system (http://theorets.univ-reims.fr, http://theorets.tsu.ru). Validation of these lists is presented throughout the present paper. For the sample of lines where upper energies were available from published analyses of experimental laboratory 12CH4 spectra, small empirical corrections in positions were introduced that could be useful for future high-resolution applications. We finally apply the TheoRetS line list to model Titan spectra as observed by VIMS and by DISR, respectively onboard Cassini and Huygens. These data are used to check that the TheoReTS line lists are able to model observations. We also make comparisons with other experimental or theoretical line lists. It appears that TheoRetS gives very reliable results better than ExoMol and even than HITRAN2012, except around 1.6 μm where it gives very similar results. We conclude that TheoReTS is suitable to be used for the modeling of planetary radiative transfer and photometry. A re-analysis of spectra recorded by the DISR instrument during the descent of the Huygens probe suggests that the CH4 mixing ratio decreases with altitude in Titan's stratosphere, reaching a value of ∼10-2 above the 110 km altitude.

  3. Narrow CIV lambda 1549A Absorption Lines in Moderate-Redshift Quasars

    DEFF Research Database (Denmark)

    Vestergaard, Marianne

    2002-01-01

    A large, high-quality spectral data base of well-selected, moderate-redshift radio-loud and radio-quiet quasars is used to characterize the incidence of narrow associated CIV lambda 1549 absorption, and how this may depend on some quasar properties, including radio-type. Preliminary results...

  4. Modeling optical properties of polymer-solvent complexes: the chloroform influence on the P3HT and N2200 absorption spectra.

    Science.gov (United States)

    Dias Ledo, Rodrigo Maia; Leal, Luciano Almeida; de Brito Silva, Patrick Pascoal; da Cunha, Wiliam Ferreira; de Souza, Leonardo Evaristo; Almeida Fonseca, Antonio Luciano; Ceschin, Artemis Marti; da Silva Filho, Demétrio Antonio; Ribeiro Junior, Luiz Antonio

    2017-02-01

    The optical properties of polymer/solvent systems composed by the polymers P3HT and PolyeraActivInk N2200 under the present of chloroform as solvent are experimentally and theoretically investigated using UV-Vis spectroscopy, molecular dynamics (MD), and density functional theory (DFT) calculations. The study is focused on obtaining the theoretical methodologies that properly describes the experimentally obtained absorption spectra of polymer-solvent complexes. In order to investigate the solvent influence, two different approaches are taken into account: the solvation shell method (SSM) and the polarizable continuum model (PCM). Our findings shown that SSM simulations, which combine MD and DFT calculations, are in good agreement with the experimental data. Moreover, it is obtained that simulations in the framework of PCM do not provide a fair description of the real system. Importantly, these results may pave the way for better descriptions of some optoelectronic properties of interest in polymer/solvent systems. Graphical Abstract ᅟ.

  5. The fluctuating population of Sm 4f configurations in topological Kondo insulator SmB6 explored with high-resolution X-ray absorption and emission spectra.

    Science.gov (United States)

    Lee, Jenn-Min; Haw, Shu-Chih; Chen, Shi-Wei; Chen, Shin-Ann; Ishii, Hirofumi; Tsuei, Ku-Ding; Hiraoka, Nozomu; Liao, Yen-Fa; Lu, Kueih-Tzu; Chen, Jin-Ming

    2017-09-12

    High-resolution partial-fluorescence-yield X-ray absorption and resonant X-ray emission spectra were used to characterize the temperature dependence of Sm 4f configurations and orbital/charge degree of freedom in SmB 6 . The variation of Sm 4f configurations responds well to the formed Kondo gap, below 140 K, and an in-gap state, below 40 K. The topological in-gap state is correlated with the fluctuating population of Sm 4f configurations that arises via carrier transfer between 3d 9 4f 6 and 3d 9 4f 5 states; both states are partially delocalized, and the mediating 5d orbital plays the role of a transfer path. Complementary results shown in this work thus manifest the importance of configuration fluctuations and orbital delocalization in the topological surface state of SmB 6 .

  6. Assignment of Pre-Edge Features in the Ru K-Edge X-Ray Absorption Spectra of Organometallic Ruthenium Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Getty, K.; Delgado-Jaime, M.U.; Kennepohl, P.

    2009-05-18

    The nature of the lowest energy bound-state transition in the Ru K-edge X-ray absorption spectra for a series of Grubbs-type ruthenium complexes was investigated. The pre-edge feature was unambiguously assigned as resulting from formally electric dipole forbidden Ru 4d {l_arrow} 1s transitions. The intensities of these transitions are extremely sensitive to the ligand environment and the symmetry of the metal centre. In centrosymmetric complexes the pre-edge is very weak since it is limited by the weak electric quadrupole intensity mechanism. By contrast, upon breaking centrosymmetry, Ru 5p-4d mixing allows for introduction of electric dipole allowed character resulting in a dramatic increase in the pre-edge intensity. The information content of this approach is explored as it relates to complexes of importance in olefin metathesis and its relevance as a tool for the study of reactive intermediates.

  7. Time dependent density functional study of the absorption spectra of 1,3-benzoxazole and three substituted benzoxazole in gas phase and liquid phase

    Energy Technology Data Exchange (ETDEWEB)

    Carrasquilla, Rafael J; Neira, Oscar L, E-mail: rjcarrasquilla@yahoo.com [Grupo de Espectroscopia Optica y Laser, Universidad Popular del Cesar, Valledupar (Colombia)

    2011-01-01

    Time dependent density functional (TD-DFT) calculations were performed on 1,3-benzoxazole and substituted benzoxazoles using the B3LYP functional and the 6-31+G(d) basis sets. The geometry of the S{sub 0} and S{sub 1} singlet ground and excited states were optimized in gas phase, toluene and methanol using B3LYP/6-31+G(d) y CIS/6-31+G(d) methods, respectively, and the vertical {pi} {yields} {pi}{sup *} absorption largest wavelength transitions were determined. Several global molecular descriptors were considered such as the hardness, chemical potential, electronegativity and the dipole moment for each molecule and was determined the influence that has, about the values of these descriptors, the alteration of the main molecular chain of an initial structure (1,3 not substituted Benzoxazole). Generally, the predicted spectra are in agreement with the experimental data.

  8. [The effect of electromagnetic waves of very high frequency of molecular spectra of radiation and absorption of nitric oxide on the functional activity of platelets].

    Science.gov (United States)

    Kirichuk, V F; Maĭborodin, A V; Volin, M V; Krenitskiĭ, A P; Tupikin, V D

    2001-01-01

    A study was made of the effect of electromagnetic EMI MMD-fluctuation on the frequencies of molecular spectra of radiation, and nitric oxide absorption under in vitro conditions on the functional activity of platelets in patients with unstable angina pectoris, with the help of a specially created generator. At amplitude-modulated and continuous modes of EMI MMD-irradiation of platelet-rich plasma for 5, 15 and 30 min the platelet functional activity decreases, which was shown up in reduction of their activation and fall of aggregative ability. The degree, to which platelet functional activity was inhibited, depended on the mode of irradiation and on duration of EMI MMD effect. The most obvious changes in platelet activation and in their readiness to aggregative response were observed at a continuous mode of irradiation within a 15 min interval.

  9. [Influence of electromagnetic emission at the frequencies of molecular absorption and emission spectra of oxygen and nitrogen oxide on the adhesion and formation of Pseudomonas aeruginosa biofilm].

    Science.gov (United States)

    Pronina, E A; Shvidenko, I G; Shub, G M; Shapoval, O G

    2011-01-01

    Evaluate the influence of electromagnetic emission (EME) at the frequencies of molecular absorption and emission spectra of atmospheric oxygen and nitrogen oxide (MAES 02 and MAES NO respectively) on the adhesion, population progress and biofilm formation of Pseudomonas aeruginosa. Adhesive activity was evaluated by mean adhesion index (MAI) of bacteria on human erythrocytes. Population growth dynamic was assessed by optical density index of broth cultures; biofilm formation--by values of optical density of the cells attached to the surface of polystyrol wells. P.aeruginosa bacteria had high adhesive properties that have increased under the influence of MAES 02 frequency emission and have not changed under the influence of MAES NO frequency. Exposure of bacteria to MAES NO frequency did not influence the population progress; exposure to MAES 02 frequency stimulated the biofilm formation ability of the bacteria, and MAES NO--decreased this ability. EME at MAES NO frequency can be used to suppress bacterial biofilm formation by pseudomonas.

  10. Impact of line parameter database, continuum absorption, full grind configuration, and L1B update on GOSAT TIR methane retrieval

    Science.gov (United States)

    Yamada, A.; Saitoh, N.; Nonogaki, R.; Imasu, R.; Shiomi, K.; Kuze, A.

    2016-12-01

    The thermal infrared (TIR) band of Thermal and Near-infrared Sensor for Carbon Observation Fourier Transform Spectrometer (TANSO-FTS) onboard Greenhouse Gases Observing Satellite (GOSAT) observes CH4 profile at wavenumber range from 1210 cm-1 to 1360 cm-1 including CH4 ν4 band. The current retrieval algorithm (V1.0) uses LBLRTM V12.1 with AER V3.1 line database to calculate optical depth. LBLRTM V12.1 include MT_CKD 2.5.2 model to calculate continuum absorption. The continuum absorption has large uncertainty, especially temperature dependent coefficient, between BPS model and MT_CKD model in the wavenumber region of 1210-1250 cm-1(Paynter and Ramaswamy, 2014). The purpose of this study is to assess the impact on CH4 retrieval from the line parameter databases and the uncertainty of continuum absorption. We used AER v1.0 database, HITRAN2004 database, HITRAN2008 database, AER V3.2 database, and HITRAN2012 database (Rothman et al. 2005, 2009, and 2013. Clough et al., 2005). AER V1.0 database is based on HITRAN2000. The CH4 line parameters of AER V3.1 and V3.2 databases are developed from HITRAN2008 including updates until May 2009 with line mixing parameters. We compared the retrieved CH4 with the HIPPO CH4 observation (Wofsy et al., 2012). The difference of AER V3.2 was the smallest and 24.1 ± 45.9 ppbv. The differences of AER V1.0, HITRAN2004, HITRAN2008, and HITRAN2012 were 35.6 ± 46.5 ppbv, 37.6 ± 46.3 ppbv, 32.1 ± 46.1 ppbv, and 35.2 ± 46.0 ppbv, respectively. Compare AER V3.2 case to HITRAN2008 case, the line coupling effect reduced difference by 8.0 ppbv. Median values of Residual difference from HITRAN2008 to AER V1.0, HITRAN2004, AER V3.2, and HITRAN2012 were 0.6 K, 0.1 K, -0.08 K, and 0.08 K, respectively, while median values of transmittance difference were less than 0.0003 and transmittance differences have small wavenumber dependence. We also discuss the retrieval error from the uncertainty of the continuum absorption, the test of full grid

  11. An upper limit for water dimer absorption in the 750 nm spectral region and a revised water line list

    Directory of Open Access Journals (Sweden)

    A. J. L. Shillings

    2011-05-01

    Full Text Available Absorption of solar radiation by water dimer molecules in the Earth's atmosphere has the potential to act as a positive feedback effect for climate change. There seems little doubt from the results of previous laboratory and theoretical studies that significant concentrations of the water dimer should be present in the atmosphere, yet attempts to detect water dimer absorption signatures in atmospheric field studies have so far yielded inconclusive results. Here we report spectral measurements in the near-infrared around 750 nm in the expected region of the | 0〈f | 4〉b|0 〉 overtone of the water dimer's hydrogen-bonded OH stretching vibration. The results were obtained using broadband cavity ringdown spectroscopy (BBCRDS, a methodology that allows absorption measurements to be made under controlled laboratory conditions but over absorption path lengths representative of atmospheric conditions. In order to account correctly and completely for the overlapping absorption of monomer molecules in the same spectral region, we have also constructed a new list of spectral data (UCL08 for the water monomer in the 750–20 000 cm−1 (13 μm–500 nm range.

    Our results show that the additional lines included in the UCL08 spectral database provide an improved representation of the measured water monomer absorption in the 750 nm region. No absorption features other than those attributable to the water monomer were detected in BBCRDS experiments performed on water vapour samples containing dimer concentrations up to an order of magnitude greater than expected in the ambient atmosphere. The absence of detectable water dimer features leads us to conclude that, in the absence of significant errors in calculated dimer oscillator strengths or monomer/dimer equilibrium constants, the widths of any water dimer absorption features present around 750 nm are of the order of 100 cm−1 HWHM, and certainly greater

  12. On the Origin of the Wide HI Absorption Line towards Sgr A

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... The position-velocity diagrams do not reveal any diffuse feature which could be attributed to a large number of HI clouds along the line of sight to Sgr A*. Consequently, the wide line has no implications either to a global population of shocked HI clouds in the Galaxy or to the energetics of the interstellar ...

  13. Förster resonance energy transfer, absorption and emission spectra in multichromophoric systems. II. Hybrid cumulant expansion.

    Science.gov (United States)

    Ma, Jian; Moix, Jeremy; Cao, Jianshu

    2015-03-07

    We develop a hybrid cumulant expansion method to account for the system-bath entanglement in the emission spectrum in the multi-chromophoric Förster transfer rate. In traditional perturbative treatments, the emission spectrum is usually expanded with respect to the system-bath coupling term in both real and imaginary time. This perturbative treatment gives a reliable absorption spectrum, where the bath is Gaussian and only the real-time expansion is involved. For the emission spectrum, the initial state is an entangled state of the system plus bath. Traditional perturbative methods are problematic when the excitations are delocalized and the energy gap is larger than the thermal energy, since the second-order expansion cannot predict the displacement of the bath. In the present method, the real-time dynamics is carried out by using the 2nd-order cumulant expansion method, while the displacement of the bath is treated more accurately by utilizing the exact reduced density matrix of the system. In a sense, the hybrid cumulant expansion is based on a generalized version of linear response theory with entangled initial states.

  14. Diffuse Reflectance Spectroscopy of Hidden Objects, Part I: Interpretation of the Reflection-Absorption-Scattering Fractions in Near-Infrared (NIR) Spectra of Polyethylene Films.

    Science.gov (United States)

    Pomerantsev, Alexey L; Rodionova, Oxana Ye; Skvortsov, Alexej N

    2017-08-01

    Investigation of a sample covered by an interfering layer is required in many fields, e.g., for process control, biochemical analysis, and many other applications. This study is based on the analysis of spectra collected by near-infrared (NIR) diffuse reflectance spectroscopy. Each spectrum is a composition of a useful, target spectrum and a spectrum of an interfering layer. To recover the target spectrum, we suggest using a new phenomenological approach, which employs the multivariate curve resolution (MCR) method. In general terms, the problem is very complex. We start with a specific problem of analyzing a system, which consists of several layers of polyethylene (PE) film and underlayer samples with known spectral properties. To separate information originating from PE layers and the target, we modify the system versus both the number of the PE layers as well as the reflectance properties of the target sample. We consider that the interfering spectrum of the layer can be modeled using three components, which can be tentatively called transmission, absorption, and scattering contributions. The novelty of our approach is that we do not remove the reflectance and scattering effects from the spectra, but study them in detail aiming to use this information to recover the target spectrum.

  15. Lowest excited states and optical absorption spectra of donor–acceptor copolymers for organic photovoltaics: a new picture emerging from tuned long-range corrected density functionals

    KAUST Repository

    Pandey, Laxman

    2012-01-01

    Polymers with low optical gaps are of importance to the organic photovoltaics community due to their potential for harnessing a large portion of the solar energy spectrum. The combination along their backbones of electron-rich and electron-deficient fragments contributes to the presence of low-lying excited states that are expected to display significant charge-transfer character. While conventional hybrid functionals are known to provide unsatisfactory results for charge-transfer excitations at the time-dependent DFT level, long-range corrected (LRC) functionals have been reported to give improved descriptions in a number of systems. Here, we use such LRC functionals, considering both tuned and default range-separation parameters, to characterize the absorption spectra of low-optical-gap systems of interest. Our results indicate that tuned LRC functionals lead to simulated optical-absorption properties in good agreement with experimental data. Importantly, the lowest-lying excited states (excitons) are shown to present a much more localized nature than initially anticipated. © 2012 the Owner Societies.

  16. On-line Incorporation of Cloud Point Extraction in Flame Atomic Absorption Spectrometric Determination of Silver

    OpenAIRE

    DALALI, Nasser; JAVADI, Nasrin; AGRAWAL, Yadvendra KUMAR

    2008-01-01

    A cloud point extraction method was incorporated into a flow injection system, coupled with flame atomic absorption spectrometry, for determination of trace amounts of silver. The analyte in the aqueous solution was acidified with 0.2 mol L-1 sulfuric acid and complexed with dithizone. The cloud point extraction was performed using the non-ionic surfactant Triton X-114. After obtaining the cloud point, the surfactant-rich phase containing the dithizonate complex was collected in a m...

  17. Absorption line profiles in a moving atmosphere - A single scattering linear perturbation theory

    Science.gov (United States)

    Hays, P. B.; Abreu, V. J.

    1989-01-01

    An integral equation is derived which linearly relates Doppler perturbations in the spectrum of atmospheric absorption features to the wind system which creates them. The perturbation theory is developed using a single scattering model, which is validated against a multiple scattering calculation. The nature and basic properties of the kernels in the integral equation are examined. It is concluded that the kernels are well behaved and that wind velocity profiles can be recovered using standard inversion techniques.

  18. Pair Natural Orbital Restricted Open-Shell Configuration Interaction (PNO-ROCIS) Approach for Calculating X-ray Absorption Spectra of Large Chemical Systems.

    Science.gov (United States)

    Maganas, Dimitrios; DeBeer, Serena; Neese, Frank

    2018-02-08

    In this work, the efficiency of first-principles calculations of X-ray absorption spectra of large chemical systems is drastically improved. The approach is based on the previously developed restricted open-shell configuration interaction singles (ROCIS) method and its parametrized version, based on a density functional theory (DFT) ground-state determinant ROCIS/DFT. The combination of the ROCIS or DFT/ROCIS methods with the well-known machinery of the pair natural orbitals (PNOs) leads to the new PNO-ROCIS and PNO-ROCIS/DFT variants. The PNO-ROCIS method can deliver calculated metal K-, L-, and M-edge XAS spectra orders of magnitude faster than ROCIS while maintaining an accuracy with calculated spectral parameters better than 1% relative to the original ROCIS method (referred to as canonical ROCIS). The method is of a black box character, as it does not require any user adjustments, while it scales quadratically with the system size. It is shown that for large systems, the size of the virtual molecular orbital (MO) space is reduced by more than 90% with respect to the canonical ROCIS method. This allows one to compute the X-ray absorption spectra of a variety of large "real-life" chemical systems featuring hundreds of atoms using a first-principles wave-function-based approach. Examples chosen from the fields of bioinorganic and solid-state chemistry include the Co K-edge XAS spectrum of aquacobalamin [H 2 OCbl] + , the Fe L-edge XAS spectrum of deoxymyoglobin (DMb), the Ti L-edge XAS spectrum of rutile TiO 2 , and the Fe M-edge spectrum of α-Fe 2 O 3 hematite. In the largest calculations presented here, molecules with more than 700 atoms and cluster models with more than 50 metal centers were employed. In all the studied cases, very good to excellent agreement with experiment is obtained. It will be shown that the PNO-ROCIS method provides an unprecedented performance of wave-function-based methods in the field of computational X-ray spectroscopy.

  19. On-line monitoring of odorant in natural gas mixtures of different composition by the infrared absorption spectroscopy method

    Science.gov (United States)

    Kireev, S. V.; Shnyrev, S. L.

    2018-03-01

    This paper reports on the results of research aimed at solving the problem of on-line monitoring of odorant in natural gas mixtures in order to make the odorization process effective and ensure the safety of main gas pipeline exploitation. Our results show that using the infrared absorption spectroscopy method is promising for this purpose. Using radiation sources operating in the spectral range 6–15 µm allows us to obtain an odorant detection sensitivity of approximately 5 ppm in gas mixtures of different composition.

  20. Digital signal processor-based high-precision on-line Voigt lineshape fitting for direct absorption spectroscopy.

    Science.gov (United States)

    Xu, Lijun; Liu, Chang; Zheng, Deyan; Cao, Zhang; Cai, Weiwei

    2014-12-01

    To realize on-line high-accuracy measurement in direct absorption spectroscopy (DAS), a system-on-chip, high-precision digital signal processor-based on-line Voigt lineshape fitting implementation is introduced in this paper. Given that the Voigt lineshape is determined by the Gauss full width at half maximum (FWHM) and Lorentz FWHM, a look-up table, which covers a range of combinations of both, is first built to achieve rapid and accurate calculation of Voigt lineshape. With the look-up table and raw absorbance data in hand, Gauss-Newton nonlinear fitting module is implemented to obtain the parameters including both the Gauss and Lorentz FWHMs, which can be used to calculate the integrated absorbance. To realize the proposed method in hardware, a digital signal processor (DSP) is adopted to fit the Voigt lineshape in a real-time DAS measurement system. In experiment, temperature and H2O concentration of a flat flame are recovered from the transitions of 7444.36 cm(-1) and 7185.6 cm(-1) by the DSP-based on-line Voigt lineshape fitting and on-line integral of the raw absorbance, respectively. The results show that the proposed method can not only fit the Voigt lineshape on-line but also improve the measurement accuracy compared with those obtained from the direct integral of the raw absorbance.

  1. WEAK HARD X-RAY EMISSION FROM TWO BROAD ABSORPTION LINE QUASARS OBSERVED WITH NuSTAR: COMPTON-THICK ABSORPTION OR INTRINSIC X-RAY WEAKNESS?

    Energy Technology Data Exchange (ETDEWEB)

    Luo, B.; Brandt, W. N. [Department of Astronomy and Astrophysics, 525 Davey Lab, The Pennsylvania State University, University Park, PA 16802 (United States); Alexander, D. M.; Hickox, R. [Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom); Harrison, F. A.; Fuerst, F.; Grefenstette, B. W.; Madsen, K. K. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Stern, D. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Bauer, F. E. [Departamento de Astronomia y Astrofisica, Pontificia Universidad Catolica de Chile, Casilla 306, Santiago 22 (Chile); Boggs, S. E.; Craig, W. W. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Christensen, F. E. [DTU Space-National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); Comastri, A. [INAF-Osservatorio Astronomico di Bologna, Via Ranzani 1, I-40127 Bologna (Italy); Fabian, A. C. [Institute of Astronomy, Madingley Road, Cambridge CB3 0HA (United Kingdom); Farrah, D. [Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States); Fiore, F. [Osservatorio Astronomico di Roma, via Frascati 33, I-00040 Monteporzio Catone (Italy); Hailey, C. J. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Matt, G. [Dipartimento di Matematica e Fisica, Universita degli Studi Roma Tre, via della Vasca Navale 84, I-00146 Roma (Italy); Ogle, P. [IPAC, California Institute of Technology, Mail Code 220-6, Pasadena, CA 91125 (United States); and others

    2013-08-01

    We present Nuclear Spectroscopic Telescope Array (NuSTAR) hard X-ray observations of two X-ray weak broad absorption line (BAL) quasars, PG 1004+130 (radio loud) and PG 1700+518 (radio quiet). Many BAL quasars appear X-ray weak, probably due to absorption by the shielding gas between the nucleus and the accretion-disk wind. The two targets are among the optically brightest BAL quasars, yet they are known to be significantly X-ray weak at rest-frame 2-10 keV (16-120 times fainter than typical quasars). We would expect to obtain Almost-Equal-To 400-600 hard X-ray ({approx}> 10 keV) photons with NuSTAR, provided that these photons are not significantly absorbed (N{sub H} {approx}< 10{sup 24} cm{sup -2}). However, both BAL quasars are only detected in the softer NuSTAR bands (e.g., 4-20 keV) but not in its harder bands (e.g., 20-30 keV), suggesting that either the shielding gas is highly Compton-thick or the two targets are intrinsically X-ray weak. We constrain the column densities for both to be N{sub H} Almost-Equal-To 7 Multiplication-Sign 10{sup 24} cm{sup -2} if the weak hard X-ray emission is caused by obscuration from the shielding gas. We discuss a few possibilities for how PG 1004+130 could have Compton-thick shielding gas without strong Fe K{alpha} line emission; dilution from jet-linked X-ray emission is one likely explanation. We also discuss the intrinsic X-ray weakness scenario based on a coronal-quenching model relevant to the shielding gas and disk wind of BAL quasars. Motivated by our NuSTAR results, we perform a Chandra stacking analysis with the Large Bright Quasar Survey BAL quasar sample and place statistical constraints upon the fraction of intrinsically X-ray weak BAL quasars; this fraction is likely 17%-40%.

  2. The role of radiative acceleration in outflows from broad absorption line QSOs. 1: Comparison with O star winds

    Science.gov (United States)

    Arav, Nahum; Li, Zhi-Yun

    1994-01-01

    We investigate the role of radiation pressure in accelerating the broad absorption line (BAL) outflows in QSOs by comparing their properties with those of radiatively driven O star winds. We find that, owing to their lower column densities and higher velocity spreads, BAL outflows have only a few tens of strong resonance lines that are dynamically important, as compared with 10(exp 3) - 10(exp 4) lines in O star winds. We show that the combined radiative force (the 'force multiplier') declines more rapidly as a function of column density for BAL outflows than for O star winds. This is mainly attributed to the absence of lines from excited states in the BAL region. The absorbing gas in BAL outflows must have a small filling factor in order for radiative acceleration to be important dynamically. This allows the absorbing material to remain at a high enough density to maintain the ion species necessary for efficient radiative acceleration as well (as those responsible for the observed absorption), without the average flow density becoming so large that the absorbing matter cannot be accelerated by an increment larger than its own sound speed. The latter condition is necessary if the outflow is to tap a large portion of the incident photon momentum. Once a small filling factor is assumed, radiative acceleration can be more efficient in BAL outflows than in O stars. We show that terminal velocities of a few times 10(exp 4) km/sec can be expected, provided that the absorbing matter does not have to drag with it a much heavier substrate.

  3. Indium determination by spectral overlappings of lines in atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Gomez, J.J.; Huicque, L. d'; Garcia Vior, L.O.

    1991-01-01

    A molybdenum hollow-cathode lamp filled with neon can be used to determine indium. Characteristic concentration for this element is 4.5 mg/L in the 325 nm spectral region for the Mo(I) 325.621 nm line. In addition, values of 0.4 mg/L and 0.3 mg/L are obtained with the Mo(I) 410.215 nm and Ne(I) 451.151 nm lines, respectively. These spectral overlappings allow the determination of indium in silver-cadmium-indium alloys. (Author) [es

  4. On-line determination of thermophysical properties in an absorption calorimeter

    Science.gov (United States)

    Otieno, F. O.; Kola, B. O.; Onyango, F. N.

    1997-03-01

    A Microsoft FORTRAN 77 algorithm for calculation of the thermal absorptance 0957-0233/8/3/004/img1 and emittance 0957-0233/8/3/004/img2 of materials for solar photothermal applications is presented. It replaces the Mathematica software package used for an earlier paper and uses data from sample heating and cooling histories obtained in an absorption calorimeter. The calorimeter is automated with a Z80 microprocessor system, which has an operating system (OS) and control programs resident in a block of type 2716 EPROMs with a working memory comprising Hitachi type 6116 static RAMs. The 0957-0233/8/3/004/img3 system acquires data from the sample through thermocouples, filters, amplifiers and analogue-to-digital signal converters (ADCs) for temporary storage in the on-board RAM. The raw data are uploaded to an IBM PS/2 microcomputer for display and processing. Solutions of heat balance equations of the calorimeter are computed from the transient temperature history data using analytical and numerical methods. Results obtained for commercial copper and aluminium samples using a 60 W tungsten - halogen lamp are discussed. They compare well with those from the Mathematica package.

  5. Investigating the reasons of variability in Si IV and C IV broad absorption line troughs of quasars

    Science.gov (United States)

    Stathopoulos, Dimitrios; Lyratzi, Evangelia; Danezis, Emmanuel; Antoniou, Antonios; Tzimeas, Dimitrios

    2017-09-01

    In this paper we analyze the C IV and Si IV broad absorption troughs of two BALQSOs (J101056.69+355833.3, J114548.38+393746.6) to the individual components they consist of. By analyzing a BAL trough to its components we have the advantage to study the variations of the individual absorbing systems in the line of sight and not just the variations of the whole absorption trough or the variations of selected portions of BAL troughs exhibiting changes. We find that the velocity shifts and FWHMs (Full Width at Half Maximum) of the individual components do not vary between an interval of six years. All variable components show changes in the optical depths at line centers which are manifested as variations in the EW (Equivalent Width) of the components. In both BALQSOs, over corresponding velocities, Si IV has higher incidence of variability than C IV. From our analysis, evidence is in favour of different covering fractions between C IV and Si IV. Finally, although most of our results favour the crossing cloud scenario as the cause of variability, there is also strong piece of evidence indicating changing ionization as the source of variability. Thus, a mixed situation where both physical mechanisms contribute to BAL variability is the most possible scenario.

  6. Measurements of Narrow Mg II Associated Absorption Doublets with ...

    Indian Academy of Sciences (India)

    1994; de Kool & Begelman 1995; Murray & Chiang. 1997; Proga et al. 2000; Everett 2005) ... One of the most popular methods to identify the intrinsic absorption lines is the time variations of absorption ... The corrections of galactic extinction are done with the reddening map of Schlegel et al. (1998). For each spectra, we fit a ...

  7. A High Galactic Latitude HI 21 cm-line Absorption Survey using the ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    observed radial velocity arising from Galaxy's rotation is unknown. Therefore, the lower Galactic latitudes are not .... In the figure, the lower panel is the Galactic rotation curve for the given line of sight obtained from the Galactic rotation model by Brand ... We thank the staff of the GMRT who made these observations possible.

  8. A Two-Line Absorption Instrument for Scramjet Temperature and Water Vapor Concentration Measurement in HYPULSE

    Science.gov (United States)

    Tsai, C. Y.

    1998-01-01

    A three beam water vapor sensor system has been modified to provide for near simultaneous temperature measurement. The system employs a tunable diode laser to scan spectral line of water vapor. The application to measurements in a scramjet combustor environment of a shock tunnel facility is discussed. This report presents and discusses die initial calibration of the measurement system.

  9. Characterization and dating of blue ballpoint pen inks using principal component analysis of UV-Vis absorption spectra, IR spectroscopy, and HPTLC.

    Science.gov (United States)

    Senior, Samir; Hamed, Ezzat; Masoud, Mamdouh; Shehata, Eman

    2012-07-01

    The ink of pens and ink extracted from lines on white photocopier paper of 10 blue ballpoint pens were subjected to ultraviolet-visible (UV-Vis) spectroscopy, infrared (IR), and high-performance thin-layer liquid chromatography (HPTLC). The R(f) values and color tones of the bands separated by thin-layer chromatography (TLC) analysis used to classify the writing inks into three groups. The principal component analysis (PCA) investigates the pen responsible for a piece of writing, and how time affects spectroscopy of written ink. PCA can differentiate between pen ink and ink line indicates the influence of solvent extraction process on the results. The PCA loadings are useful in individualization of a questioned ink from a database. The PCA of ink lines extracted at different times can be used to estimate the time at which a questioned document was written. The results proved that the UV-Vis spectra are effective tool to separate blue ballpoint pen ink in most cases rather than IR and HPTLC. © 2012 American Academy of Forensic Sciences.

  10. Studying the complex BAL profiles in the BALQSOs spectra

    Energy Technology Data Exchange (ETDEWEB)

    Lyratzi, E; Danezis, E; Popovic, L C; Antoniou, A; Dimitrijevic, M S; Stathopoulos, D, E-mail: elyratzi@phys.uoa.gr

    2010-11-01

    Most of Broad Absorption Lines (BALs) in quasars (QSOs) present very complex profiles. This means that we cannot fit them with a known physical distribution. An idea to explain these profiles is that the dynamical systems of Broad Line Regions (BLRs) are not homogeneous but consist of a number of density regions or ion populations with different physical parameters. Each one of these density regions gives us an independent classical absorption line. If the regions that give rise to such lines rotate with large velocities and move radially with small velocities, the produced lines have large widths and small shifts. As a result they are blended among themselves as well as with the main spectral line and thus they are not discrete. Based on this idea we study the BALs of UV C IV resonance lines in the spectra of a group of Hi ionization Broad Absorption Line Quasars (Hi BALQSOs) using the Gauss-Rotation model (GR model).

  11. X-Raying the Ultraluminous Infrared Starburst Galaxy and Broad Absorption Line QSO Markarian 231 with Chandra

    Science.gov (United States)

    Gallagher, S. C.; Brandt, W. N.; Chartas, G.; Garmire, G. P.; Sambruna, R. M.

    2002-01-01

    With 40 ks of Clzandra ACIS-S3 exposure, new information on both the starburst and QSO components of the X-ray emission of Markarian 231, an ultraluminous infrared galaxy and broad absorption line QSO, has been obtained. The bulk of the X-ray luminosity is emitted from an unresolved nuclear point source, and the spectrum is remarkably hard, with the majority of the flux emitted above 2 keV. Most notably, significant nuclear variability (a decrease of -45% in approximately 6 hr) at energies above 2 keV indicates that Chuizdra has probed within light-hours of the central black hole. Although we concur with Maloney & Reynolds that the direct continuum is not observed, this variability coupled with the 188 eV upper limit on the equivalent width of the Fe K o emission line argues against the reflection-dominated model put forth by these authors based on their ASCA data. Instead, we favor a model in which a small, Compton-thick absorber blocks the direct X-rays, and only indirect, scattered X-rays from multiple lines of sight can reach the observer. Extended soft, thermal emission encompasses the optical extent of the galaxy and exhibits resolved structure. An off-nuclear X-ray source with a 0.35-8.0 keV luminosity of Lx = 7 x 10 sup39 ergs s sup -1 , consistent with the ultraluminous X-ray sources in other nearby starbursts, is detected. We also present an unpublished Faint Object Spectrograph spectrum from the Hirhhle Spuce Telescope archive showing the broad C IV absorption.

  12. Study of the Many Fluorescent Lines and the Absorption Variability in GX 301-2 with XMM-Newton

    Science.gov (United States)

    Fuerst, F.; Suchy, S.; Kreykenbohm, I.; Barragan, L.; Wilms, J.; Pottschmidt, K.; Caballero, I.; Kretschmar, P.; Ferrigno, C.; Rothschild, R. E.

    2011-01-01

    We present an in-depth study of the High Mass X-ray Binary (HMXB) GX 301-2 during its pre-periastron flare using data from the XMM-Newton satellite. The energy spectrum shows a power law continuum absorbed by a large equivalent hydrogen column on the order of 10(exp 24)/ sq cm and a prominent Fe K-alpha fluorescent emission line. Besides the Fe K-alpha line, evidence for Fe K-Beta, Ni K-alpha, Ni K-Beta, S K-alpha, Ar K-alpha, Ca K-alpha, and Cr K-alpha fluorescent lines is found. The observed line strengths are consistent with fluorescence in a cold absorber. This is the first time that Cr K-alpha is seen in emission in the X-ray spectrum of a HMXB. In addition to the modulation by the strong pulse period of approx 685 sec the source is highly variable and shows different states of activity. We perform time-resolved as well as pulse-to-pulse resolved spectroscopy to investigate differences between these states of activity. We find that fluorescent line fluxes are strongly variable and generally follow the overall flux. The N-H value is variable by a factor of 2, but not correlated to continuum normalization. We find an interval of low flux in the light curve in which the pulsations cease almost completely, without any indication of an increasing absorption column. We investigate this dip in detail and argue that it is most likely that during the dip the accretion ceased and the afterglow of the fluorescent iron accounted for the main portion of the X-ray flux. A similar dip was found earlier in RXTE data, and we compare our findings to these results.

  13. In-Line Capacitance Sensor for Real-Time Water Absorption Measurements

    Science.gov (United States)

    Nurge, Mark A.; Perusich, Stephen A.

    2010-01-01

    A capacitance/dielectric sensor was designed, constructed, and used to measure in real time the in-situ water concentration in a desiccant water bed. Measurements were carried out with two experimental setups: (1) passing nitrogen through a humidity generator and allowing the gas stream to become saturated at a measured temperature and pressure, and (2) injecting water via a syringe pump into a nitrogen stream. Both water vapor generating devices were attached to a downstream vertically-mounted water capture bed filled with 19.5 g of Moisture Gone desiccant. The sensor consisted of two electrodes: (1) a 1/8" dia stainless steel rod placed in the middle of the bed and (2) the outer shell of the stainless steel bed concentric with the rod. All phases of the water capture process (background, heating, absorption, desorption, and cooling) were monitored with capacitance. The measured capacitance was found to vary linearly with the water content in the bed at frequencies above 100 kHz indicating dipolar motion dominated the signal; below this frequency, ionic motion caused nonlinearities in the water concentration/capacitance relationship. The desiccant exhibited a dielectric relaxation whose activation energy was lowered upon addition of water indicating either a less hindered rotational motion or crystal reorientation.

  14. EVIDENCE FOR ULTRA-FAST OUTFLOWS IN RADIO-QUIET ACTIVE GALACTIC NUCLEI. II. DETAILED PHOTOIONIZATION MODELING OF Fe K-SHELL ABSORPTION LINES

    International Nuclear Information System (INIS)

    Tombesi, F.; Cappi, M.; Dadina, M.; Reeves, J. N.; Palumbo, G. G. C.; Braito, V.

    2011-01-01

    X-ray absorption line spectroscopy has recently shown evidence for previously unknown Ultra-fast Outflows (UFOs) in radio-quiet active galactic nuclei (AGNs). These have been detected essentially through blueshifted Fe XXV/XXVI K-shell transitions. In the previous paper of this series we defined UFOs as those highly ionized absorbers with an outflow velocity higher than 10,000 km s –1 and assessed the statistical significance of the associated blueshifted absorption lines in a large sample of 42 local radio-quiet AGNs observed with XMM-Newton. The present paper is an extension of that work. First, we report a detailed curve of growth analysis of the main Fe XXV/XXVI transitions in photoionized plasmas. Then, we estimate an average spectral energy distribution for the sample sources and directly model the Fe K absorbers in the XMM-Newton spectra with the detailed Xstar photoionization code. We confirm that the frequency of sources in the radio-quiet sample showing UFOs is >35% and that the majority of the Fe K absorbers are indeed associated with UFOs. The outflow velocity distribution spans from ∼10,000 km s –1 (∼0.03c) up to ∼100,000 km s –1 (∼0.3c), with a peak and mean value of ∼42,000 km s –1 (∼0.14c). The ionization parameter is very high and in the range log ξ ∼ 3-6 erg s –1 cm, with a mean value of log ξ ∼ 4.2 erg s –1 cm. The associated column densities are also large, in the range N H ∼ 10 22 -10 24 cm –2 , with a mean value of N H ∼ 10 23 cm –2 . We discuss and estimate how selection effects, such as those related to the limited instrumental sensitivity at energies above 7 keV, may hamper the detection of even higher velocities and higher ionization absorbers. We argue that, overall, these results point to the presence of extremely ionized and possibly almost Compton-thick outflowing material in the innermost regions of AGNs. This also suggests that UFOs may potentially play a significant role in the expected

  15. Evidence for Ultra-fast Outflows in Radio-quiet Active Galactic Nuclei. II. Detailed Photoionization Modeling of Fe K-shell Absorption Lines

    Science.gov (United States)

    Tombesi, F.; Cappi, M.; Reeves, J. N.; Palumbo, G. G. C.; Braito, V.; Dadina, M.

    2011-11-01

    X-ray absorption line spectroscopy has recently shown evidence for previously unknown Ultra-fast Outflows (UFOs) in radio-quiet active galactic nuclei (AGNs). These have been detected essentially through blueshifted Fe XXV/XXVI K-shell transitions. In the previous paper of this series we defined UFOs as those highly ionized absorbers with an outflow velocity higher than 10,000 km s-1 and assessed the statistical significance of the associated blueshifted absorption lines in a large sample of 42 local radio-quiet AGNs observed with XMM-Newton. The present paper is an extension of that work. First, we report a detailed curve of growth analysis of the main Fe XXV/XXVI transitions in photoionized plasmas. Then, we estimate an average spectral energy distribution for the sample sources and directly model the Fe K absorbers in the XMM-Newton spectra with the detailed Xstar photoionization code. We confirm that the frequency of sources in the radio-quiet sample showing UFOs is >35% and that the majority of the Fe K absorbers are indeed associated with UFOs. The outflow velocity distribution spans from ~10,000 km s-1 (~0.03c) up to ~100,000 km s-1 (~0.3c), with a peak and mean value of ~42,000 km s-1 (~0.14c). The ionization parameter is very high and in the range log ξ ~ 3-6 erg s-1 cm, with a mean value of log ξ ~ 4.2 erg s-1 cm. The associated column densities are also large, in the range N H ~ 1022-1024 cm-2, with a mean value of N H ~ 1023 cm-2. We discuss and estimate how selection effects, such as those related to the limited instrumental sensitivity at energies above 7 keV, may hamper the detection of even higher velocities and higher ionization absorbers. We argue that, overall, these results point to the presence of extremely ionized and possibly almost Compton-thick outflowing material in the innermost regions of AGNs. This also suggests that UFOs may potentially play a significant role in the expected cosmological feedback from AGNs and their study can

  16. A global method for handling fluorescence spectra at high concentration derived from the competition between emission and absorption of colloidal CdTe quantum dots.

    Science.gov (United States)

    Noblet, Thomas; Dreesen, Laurent; Hottechamps, Julie; Humbert, Christophe

    2017-10-11

    We investigate the effects of the concentration of CdTe quantum dots (QDs) on their fluorescence in water. The emission spectra, acquired in right angle geometry, exhibit highly variable shapes. The measurements evidence a critical value of the concentration beyond which the intensity and the spectral bandwidth decrease and the fluorescence maximum is redshifted. To account for these observations, we develop a model based on the primary and secondary inner filter effects. The accuracy of the model ensures that the concentration dependent behaviour of QD fluorescence is completely due to inner filter effects. This result is all the more interesting because it precludes the assumption of dynamic quenching. As a matter of fact, the decrease of the emission intensity is not a consequence of collisional quenching but an effect of competition between fluorescence and absorption. We even show that this phenomenon is linked not only to the QD concentration but also to the geometric configuration of the setup. Hence, our analytical model can be easily adapted to every fluorescence spectroscopy configuration to quantitatively predict or correct inner filter effects in the case of QDs or any fluorophore, and thus improve the handling of fluorescence spectroscopy for highly concentrated solutions.

  17. Fermi resonance and strong anharmonic effects in the absorption spectra of the ν-OH ( ν-OD) vibration of solid H- and D-benzoic acid

    Science.gov (United States)

    Yaremko, A. M.; Ratajczak, H.; Barnes, A. J.; Baran, J.; Durlak, P.; Latajka, Z.

    2009-10-01

    The vibrational spectra of polycrystalline benzoic acid (BA) and its deuterated derivative were studied over the wide frequency region 4000-10 cm -1 by IR and Raman methods. A theoretical analysis of the hydrogen bond frequency region and calculations at the B3LYP/6-311++G(2d, 2p) level for the benzoic acid cyclic dimer in the gas phase were made. In order to study the dynamics of proton transfer two formalisms were applied: Car-Parrinello Molecular Dynamics (CPMD) and Path Integrals Molecular Dynamics (PIMD). It was shown that the experimentally observed very broad ν-OH band absorption is the result of complex anharmonic interaction: Fermi resonance between the OH-stretching and bending vibrations and strong interaction of the ν-OH stretching with the low frequency phonons. The theoretical analysis in the framework of such an approach gave a good correlation with experiment. From the CPMD calculations it was confirmed that the O-H⋯O bridge is not rigid, with the O⋯O distance being described by a large amplitude motion. For the benzoic acid dimer we observed stepwise (asynchronous) proton transfer.

  18. Infrared Absorption Spectra, Radiative Efficiencies, and Global Warming Potentials of Newly-Detected Halogenated Compounds: CFC-113a, CFC-112 and HCFC-133a

    Directory of Open Access Journals (Sweden)

    Maryam Etminan

    2014-07-01

    Full Text Available CFC-113a (CF3CCl3, CFC-112 (CFCl2CFCl2 and HCFC-133a (CF3CH2Cl are three newly detected molecules in the atmosphere that are almost certainly emitted as a result of human activity. It is important to characterise the possible contribution of these gases to radiative forcing of climate change and also to provide information on the CO2-equivalence of their emissions. We report new laboratory measurements of absorption cross-sections of these three compounds at a resolution of 0.01 cm−1 for two temperatures 250 K and 295 K in the spectral range of 600–1730 cm−1. These spectra are then used to calculate the radiative efficiencies and global warming potentials (GWP. The radiative efficiencies are found to be between 0.15 and 0.3 W∙m−2∙ppbv−1. The GWP for a 100 year time horizon, relative to carbon dioxide, ranges from 340 for the relatively short-lived HCFC-133a to 3840 for the longer-lived CFC-112. At current (2012 concentrations, these gases make a trivial contribution to total radiative forcing; however, the concentrations of CFC-113a and HCFC-133a are continuing to increase. The 2012 CO2-equivalent emissions, using the GWP (100, are estimated to be about 4% of the current global CO2-equivalent emissions of HFC-134a.

  19. The spectral-line moment-based (SLMB) modeling of the wide band and global blackbody-weighted transmission function and cumulative distribution function of the absorption coefficient in uniform gaseous media

    Energy Technology Data Exchange (ETDEWEB)

    Andre, Frederic [Centre de Thermique de Lyon (CETHIL, CNRS-INSA Lyon-UCBL), Bat. Sadi Carnot, INSA-Lyon, Lyon F-69621 (France)], E-mail: frederic.andre@insa-lyon.fr; Vaillon, Rodolphe [Centre de Thermique de Lyon (CETHIL, CNRS-INSA Lyon-UCBL), Bat. Sadi Carnot, INSA-Lyon, Lyon F-69621 (France)

    2008-09-15

    The spectral-line moment-based (SLMB) modeling is proposed for the calculation of radiative properties of gases on any spectral width. The associated mathematical formulation is obtained by applying several concepts of the k-distribution methods such as the reordering of the wavenumber scale by monotonic variations of the absorption coefficient, together with the application of the k-moment method's principles. This approach gives both a general formula for the BTF and a simple and readily applicable approximation for the blackbody-weighted cumulated k-distribution function of the absorption coefficient. The model is applied for the computation of wide band BTFs and cumulative k-distributions for uniform columns of CO{sub 2} and H{sub 2}O in the temperature range (300-2400 K) at atmospheric pressure. Model parameters are deduced from line-by-line (LBL) spectra calculated using the HITEMP database. Comparisons with LBL reference data as well as with contemporary modeling approaches (SLW, FSK, SNB) are performed and discussed.

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

    Science.gov (United States)

    Qu, Zhechao; Werhahn, Olav; Ebert, Volker

    2018-01-01

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

  1. Infrared Spectroscopy of CO Ro-Vibrational Absorption Lines toward the Obscured AGN IRAS 08572+3915

    Science.gov (United States)

    Shirahata, Mai; Nakagawa, Takao; Usuda, Tomonori; Goto, Miwa; Suto, Hiroshi; Geballe, Thomas R.

    2013-02-01

    We present high-resolution spectroscopy of gaseous CO absorption in the fundamental ro-vibrational band toward the heavily obscured active galactic nucleus (AGN) IRAS 08572+3915. We have detected absorption lines up to highly excited rotational levels (J ≤ 17). The velocity profiles reveal three distinct components, the strongest and broadest (Δυ > 200 km s-1) of which is due to blueshifted (-160 km s-1) gas at a temperature of ˜270 K absorbing at velocities as high as -400 km s-1. A much weaker but even warmer (˜700 K) component, which is highly redshifted (+100 km s-1), is also detected, in addition to a cold (˜20 K) component centered at the systemic velocity of the galaxy. On the assumption of local thermodynamic equilibrium, the column density of CO in the 270 K component is NCO ˜4.5 × 1018 cm-2, which in fully molecular gas corresponds to an H2 column density of NH2 ˜ 2.5 × 1022 cm-2. The thermal excitation of CO up to the observed high rotational levels requires a density greater than nc (H2) > 2 × 107cm-3, implying that the thickness of the warm absorbing layer is extremely small (Δd warm components, as well as their temperatures, indicate that they originate in molecular clouds near the central engine of the AGN.

  2. Atmospheric profiling via satellite to satellite occultations near water and ozone absorption lines for weather and climate

    Science.gov (United States)

    Kursinski, E. R.; Ward, D.; Otarola, A. C.; McGhee, J.; Stovern, M.; Sammler, K.; Reed, H.; Erickson, D.; McCormick, C.; Griggs, E.

    2016-05-01

    Significantly reducing weather and climate prediction uncertainty requires global observations with substantially higher information content than present observations provide. While GPS occultations have provided a major advance, GPS observations of the atmosphere are limited by wavelengths chosen specifically to minimize interaction with the atmosphere. Significantly more information can be obtained via satellite to satellite occultations made at wavelengths chosen specifically to characterize the atmosphere. Here we describe such a system that will probe cm- and mmwavelength water vapor absorption lines called the Active Temperature, Ozone and Moisture Microwave Spectrometer (ATOMMS). Profiling both the speed and absorption of light enables ATOMMS to profile temperature, pressure and humidity simultaneously, which GPS occultations cannot do, as well as profile clouds and turbulence. We summarize the ATOMMS concept and its theoretical performance. We describe field measurements made with a prototype ATOMMS instrument and several important capabilities demonstrated with those ground based measurements including retrieving temporal variations in path-averaged water vapor to 1%, in clear, cloudy and rainy conditions, up to optical depths of 17, remotely sensing turbulence and determining rain rates. We conclude with a vision of a future ATOMMS low Earth orbiting satellite constellation designed to take advantage of synergies between observational needs for weather and climate, ATOMMS unprecedented orbital remote sensing capabilities and recent cubesat technological innovations that enable a constellation of dozens of very small spacecraft to achieve many critical, but as yet unfulfilled, monitoring and forecasting needs.

  3. Erratum: "Photoionization Modeling of Oxygen K Absorption in the Interstellar Medium, the Chandra Grating Spectra of XTE J1817-330" (2013, Apj, 768, 60)

    Science.gov (United States)

    Gatuzz, E.; Garcia, J.; Mendoza, C.; Kallman, Timothy R.; Witthoeft, Michael C.; Lohfink, A.; Bautista, M. A.; Palmeri, P.; Quinet, P.

    2013-01-01

    In the published version of this paper, there are some minor inaccuracies in the absorption-line wavelengths listed in Table 4 as a result of a faulty reduction procedure of the Obs6615 spectrum. The shifts have been detected in a comparison with the wavelengths listed for this spectrum in the Chandra Transmission Grating Catalog and Archive (TGCat8). They are due to incorrect centroid positions of the zero-order image in both reductions as determined by the tgdetect utility which, when disentangled, yield the improved line positions of the amended Table 4 given below. It must also be pointed out that other quantitative findings of the original paper: 1. Table 5, p. 9: the column density (NH), ionization parameter, oxygen abundance of the warmabs model and the normalization and photon index of the power-law model; 2. Table 6, p. 9: the hydrogen column density of the warmabs fit; 3. Table 7, p. 9: the present oxygen equivalent widths of XTE J1817-330; and 4. Table 8, p. 10: the present oxygen column densities of XTE J1817-330 derived from both the curve of growth and warmabs model fit have been revised in the new light and are, within the estimated uncertainty ranges, in good accord with the new rendering.

  4. Revealing discriminating power of the elements in edible sea salts: Line-intensity correlation analysis from laser-induced plasma emission spectra

    International Nuclear Information System (INIS)

    Lee, Yonghoon; Ham, Kyung-Sik; Han, Song-Hee; Yoo, Jonghyun; Jeong, Sungho

    2014-01-01

    We have investigated the discriminating power of the elements in edible sea salts using Laser-Induced Breakdown Spectroscopy (LIBS). For the ten different sea salts from South Korea, China, Japan, France, Mexico and New Zealand, LIBS spectra were recorded in the spectral range between 190 and 1040 nm, identifying the presence of Na, Cl, K, Ca, Mg, Li, Sr, Al, Si, Ti, Fe, C, O, N, and H. Intensity correlation analysis of the observed emission lines provided a valuable insight into the discriminating power of the different elements in the sea salts. The correlation analysis suggests that the elements with independent discrimination power can be categorized into three groups; those that represent dissolved ions in seawater (K, Li, and Mg), those that are associated with calcified particles (Ca and Sr), and those that are present in soils contained in the sea salts (Al, Si, Ti, and Fe). Classification models using a few emission lines selected based on the results from intensity correlation analysis and full broadband LIBS spectra were developed based on Principal Component Analysis (PCA) and Partial Least Squares-Discriminant Analysis (PLS-DA) and their performances were compared. Our results indicate that effective combination of a few emission lines can provide a dependable model for discriminating the edible sea salts and the performance is not much degraded from that based on the full broadband spectra. This can be rationalized by the intensity correlation results. - Highlights: • Broadband LIBS spectra of various edible sea salts were obtained. • Intensity correlation of emission lines of the elements in edible sea salts was analyzed. • The elements were categorized into three groups with independent discriminating power. • The effective combination of a few lines can provide dependable classification models

  5. Revealing discriminating power of the elements in edible sea salts: Line-intensity correlation analysis from laser-induced plasma emission spectra

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yonghoon, E-mail: yhlee@mokpo.ac.kr [Department of Chemistry, Mokpo National University, Jeonnam 534-729 (Korea, Republic of); Ham, Kyung-Sik [Department of Food Engineering, Mokpo National University, Jeonnam 534-729 (Korea, Republic of); Han, Song-Hee [Division of Maritime Transportation System, Mokpo National Maritime University, Jeonnam 530-729 (Korea, Republic of); Yoo, Jonghyun, E-mail: jyoo@appliedspectra.com [Applied Spectra, Inc., 46665 Fremont Boulevard, Fremont, CA 94538 (United States); Jeong, Sungho [School of Mechatronics, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of)

    2014-11-01

    We have investigated the discriminating power of the elements in edible sea salts using Laser-Induced Breakdown Spectroscopy (LIBS). For the ten different sea salts from South Korea, China, Japan, France, Mexico and New Zealand, LIBS spectra were recorded in the spectral range between 190 and 1040 nm, identifying the presence of Na, Cl, K, Ca, Mg, Li, Sr, Al, Si, Ti, Fe, C, O, N, and H. Intensity correlation analysis of the observed emission lines provided a valuable insight into the discriminating power of the different elements in the sea salts. The correlation analysis suggests that the elements with independent discrimination power can be categorized into three groups; those that represent dissolved ions in seawater (K, Li, and Mg), those that are associated with calcified particles (Ca and Sr), and those that are present in soils contained in the sea salts (Al, Si, Ti, and Fe). Classification models using a few emission lines selected based on the results from intensity correlation analysis and full broadband LIBS spectra were developed based on Principal Component Analysis (PCA) and Partial Least Squares-Discriminant Analysis (PLS-DA) and their performances were compared. Our results indicate that effective combination of a few emission lines can provide a dependable model for discriminating the edible sea salts and the performance is not much degraded from that based on the full broadband spectra. This can be rationalized by the intensity correlation results. - Highlights: • Broadband LIBS spectra of various edible sea salts were obtained. • Intensity correlation of emission lines of the elements in edible sea salts was analyzed. • The elements were categorized into three groups with independent discriminating power. • The effective combination of a few lines can provide dependable classification models.

  6. Brush border membrane vesicle and Caco-2 cell line: Two experimental models for evaluation of absorption enhancing effects of saponins, bile salts, and some synthetic surfactants.

    Science.gov (United States)

    Moghimipour, Eskandar; Tabassi, Sayyed Abolghassem Sajadi; Ramezani, Mohammad; Handali, Somayeh; Löbenberg, Raimar

    2016-01-01

    The aim of this study was to investigate the influence of absorption enhancers in the uptake of hydrophilic compounds. The permeation of the two hydrophilic drug models gentamicin and 5 (6)-carboxyfluorescein (CF) across the brush border membrane vesicles and Caco-2 cell lines were evaluated using total saponins of Acanthophyllum squarrosum, Quillaja saponaria, sodium lauryl sulfate, sodium glycocholate, sodium taurodeoxycholate, and Tween 20 as absorption enhancers. Transepithelial electrical resistance (TEER) measurement was utilized to assess the paracellular permeability of cell lines. Confocal laser scanning microscopy (CLSM) was performed to obtain images of the distribution of CF in Caco-2 cells. These compounds were able to loosen tight junctions, thus increasing paracellular permeability. CLSM confirmed the effect of these absorption enhancers on CF transport across Caco-2 lines and increased the Caco-2 permeability via transcellular route. It was also confirmed that the decrease in TEER was transient and reversible after removal of permeation enhancers.

  7. Brush border membrane vesicle and Caco-2 cell line: Two experimental models for evaluation of absorption enhancing effects of saponins, bile salts, and some synthetic surfactants

    Directory of Open Access Journals (Sweden)

    Eskandar Moghimipour

    2016-01-01

    Full Text Available The aim of this study was to investigate the influence of absorption enhancers in the uptake of hydrophilic compounds. The permeation of the two hydrophilic drug models gentamicin and 5 (6-carboxyfluorescein (CF across the brush border membrane vesicles and Caco-2 cell lines were evaluated using total saponins of Acanthophyllum squarrosum, Quillaja saponaria, sodium lauryl sulfate, sodium glycocholate, sodium taurodeoxycholate , and Tween 20 as absorption enhancers. Transepithelial electrical resistance (TEER measurement was utilized to assess the paracellular permeability of cell lines. Confocal laser scanning microscopy (CLSM was performed to obtain images of the distribution of CF in Caco-2 cells. These compounds were able to loosen tight junctions, thus increasing paracellular permeability. CLSM confirmed the effect of these absorption enhancers on CF transport across Caco-2 lines and increased the Caco-2 permeability via transcellular route. It was also confirmed that the decrease in TEER was transient and reversible after removal of permeation enhancers.

  8. Brush border membrane vesicle and Caco-2 cell line: Two experimental models for evaluation of absorption enhancing effects of saponins, bile salts, and some synthetic surfactants

    Science.gov (United States)

    Moghimipour, Eskandar; Tabassi, Sayyed Abolghassem Sajadi; Ramezani, Mohammad; Handali, Somayeh; Löbenberg, Raimar

    2016-01-01

    The aim of this study was to investigate the influence of absorption enhancers in the uptake of hydrophilic compounds. The permeation of the two hydrophilic drug models gentamicin and 5 (6)-carboxyfluorescein (CF) across the brush border membrane vesicles and Caco-2 cell lines were evaluated using total saponins of Acanthophyllum squarrosum, Quillaja saponaria, sodium lauryl sulfate, sodium glycocholate, sodium taurodeoxycholate, and Tween 20 as absorption enhancers. Transepithelial electrical resistance (TEER) measurement was utilized to assess the paracellular permeability of cell lines. Confocal laser scanning microscopy (CLSM) was performed to obtain images of the distribution of CF in Caco-2 cells. These compounds were able to loosen tight junctions, thus increasing paracellular permeability. CLSM confirmed the effect of these absorption enhancers on CF transport across Caco-2 lines and increased the Caco-2 permeability via transcellular route. It was also confirmed that the decrease in TEER was transient and reversible after removal of permeation enhancers. PMID:27429925

  9. DFT/TD-semiempirical study on the structural and electronic properties and absorption spectra of supramolecular fullerene-porphyrine-metalloporphyrine triads based dye-sensitized solar cells

    Science.gov (United States)

    Rezvani, M.; Darvish Ganji, M.; Jameh-Bozorghi, S.; Niazi, A.

    2018-04-01

    In the present work density functional theory (DFT) and time-dependent semiempirical ZNIDO/S (TD-ZNIDO/S) methods have been used to investigate the ground state geometries, electronic structures and excited state properties of triad systems. The influences of the type of metal in the porphyrin ring, change in bridge position and porphyrine-ZnP duplicate on the energies of frontier molecular orbital and UV-Vis spectra has been studied. Geometry optimization, the energy levels and electron density of the Highest Occupied Molecular Orbital (HOMO) and the Lowest Unoccupied Molecular Orbital (LUMO), chemical hardness (η), electrophilicity index (ω), electron accepting power (ω+) were calculated using ZINDO/S method to predict which molecule is the most efficient with a great capability to be used as a triad molecule in solar industry. Moreover the light harvesting efficiency (LHE) was calculated by means of the oscillator strengths which are obtained by TD-ZINDO/S calculation. Theoretical studies of the electronic spectra by ZINDO/S method were helpful in interpreting the observed electronic transitions. This aspect was systematically explored in a series of C60-Porphyrine-Metalloporphyrine (C60-P-Mp) triad system with M being Fe, Co, Ni, Ti, and Zn. Generally, transition metal coordination compounds are used as effective sensitizers, due to their intense charge-transfer absorption over the whole visible range and highly efficient metal-to-ligand charge transfer. We aim to optimize the performance of the title solar cells by altering the frontier orbital energy gaps. The results reveal that cell efficiency can be enhanced by metal functionalization of the free base porphyrin. Ti-porphyrin was found to be the most efficient dye sensitizer for dye sensitized solar cells (DSSCs) based on C60-P-Mptriad system due to C60-Por-TiP complex has lower chemical hardness, gap energy and chemical potential as well as higher electron accepting power among other complexes. In

  10. [A Study of the Relationship Among Genetic Distances, NIR Spectra Distances, and NIR-Based Identification Model Performance of the Seeds of Maize Iinbred Lines].

    Science.gov (United States)

    Liu, Xu; Jia, Shi-qiang; Wang, Chun-ying; Liu, Zhe; Gu, Jian-cheng; Zhai, Wei; Li, Shao-ming; Zhang, Xiao-dong; Zhu, De-hai; Huang, Hua-jun; An, Dong

    2015-09-01

    This paper explored the relationship among genetic distances, NIR spectra distances and NIR-based identification model performance of the seeds of maize inbred lines. Using 3 groups (total 15 pairs) of maize inbred lines whose genetic distaches are different as experimental materials, we calculates the genetic distance between these seeds with SSR markers and uses Euclidean distance between distributed center points of maize NIR spectrum in the PCA space as the distances of NIR spectrum. BPR method is used to build identification model of inbred lines and the identification accuracy is used as a measure of model identification performance. The results showed that, the correlation of genetic distance and spectra distancesis 0.9868, and it has a correlation of 0.9110 with the identification accuracy, which is highly correlated. This means near-Infrared spectrum of seedscan reflect genetic relationship of maize inbred lines. The smaller the genetic distance, the smaller the distance of spectrum, the poorer ability of model to identify. In practical application, near infrared spectrum analysis technology has the potential to be used to analyze maize inbred genetic relations, contributing much to genetic breeding, identification of species, purity sorting and so on. What's more, when creating a NIR-based identification model, the impact of the maize inbred lines which have closer genetic relationship should be fully considered.

  11. Revealing discriminating power of the elements in edible sea salts: Line-intensity correlation analysis from laser-induced plasma emission spectra

    Science.gov (United States)

    Lee, Yonghoon; Ham, Kyung-Sik; Han, Song-Hee; Yoo, Jonghyun; Jeong, Sungho

    2014-11-01

    We have investigated the discriminating power of the elements in edible sea salts using Laser-Induced Breakdown Spectroscopy (LIBS). For the ten different sea salts from South Korea, China, Japan, France, Mexico and New Zealand, LIBS spectra were recorded in the spectral range between 190 and 1040 nm, identifying the presence of Na, Cl, K, Ca, Mg, Li, Sr, Al, Si, Ti, Fe, C, O, N, and H. Intensity correlation analysis of the observed emission lines provided a valuable insight into the discriminating power of the different elements in the sea salts. The correlation analysis suggests that the elements with independent discrimination power can be categorized into three groups; those that represent dissolved ions in seawater (K, Li, and Mg), those that are associated with calcified particles (Ca and Sr), and those that are present in soils contained in the sea salts (Al, Si, Ti, and Fe). Classification models using a few emission lines selected based on the results from intensity correlation analysis and full broadband LIBS spectra were developed based on Principal Component Analysis (PCA) and Partial Least Squares-Discriminant Analysis (PLS-DA) and their performances were compared. Our results indicate that effective combination of a few emission lines can provide a dependable model for discriminating the edible sea salts and the performance is not much degraded from that based on the full broadband spectra. This can be rationalized by the intensity correlation results.

  12. Study on the interactions of antiemetic drugs and 12-tungstophosphoric acid by absorption and resonance Rayleigh scattering spectra and their analytical applications

    Science.gov (United States)

    Wang, Yaqiong; Liu, Shaopu; Liu, Zhongfang; Yang, Jidong; Hu, Xiaoli

    2013-03-01

    In 0.1 mol L-1 HCl medium, antiemetic drugs (ATM), such as granisetron hydrochloride (GS) and tropisetron hydrochloride (TS), reacted with H3PW12O40·nH2O and formed 3:1 ion-association complex of [(ATM)3PW12O40], then self-aggregated into nanoparticles-[(ATM)3PW12O40]n with an average size of 100 nm. The reaction resulted in the enhancement of resonance Rayleigh scattering (RRS) and the absorption spectra. The increments of scattering intensity (ΔIRRS) and the change of absorbance (ΔA) were both directly proportional to the concentrations of ATM in certain ranges. Accordingly, two new RRS and spectrophotometric methods were proposed for ATM detection. The detection limits (3σ) of GS and TS were 3.2 ng mL-1 and 4.0 ng mL-1(RRS method), 112.5 ng mL-1 and 100.0 ng mL-1(spectrophotometric method). These two methods were applied to determine GS in orally disintegrating tablets and the results were in good agreement with the official method. The ground-state geometries and electronic structures of GS and TS were optimized by the hybrid density functional theory (DFT) method and the shape of [(ATM)3PW12O40]n was characterized by atomic force microscopy (AFM). Take the RRS method with higher sensitivity as an example, the reaction mechanism and the reasons for enhancement of scattering were discussed.

  13. Comparison of measured and calculated neutron and gamma-ray energy spectra behind an in-line shielded duct

    International Nuclear Information System (INIS)

    Santoro, R.T.; Alsmiller, R.G. Jr.; Barnes, J.M.; Chapman, G.T.; Tang, J.S.

    1982-05-01

    Integral experiments that measure the transport of approx. 14 MeV neutrons through a 0.30-m-diameter duct having a length-to-diameter ratio of 2.83 that is partially plugged with a 0.15 m diameter, 0.51 m long shield comprised of alternating layers of stainless steel type 304 and borated polyethylene have been carried out at the Oak Ridge National Laboratory. Measured and calculated neutron and gamma ray energy spectra are compared at several locations relative to the mouth of the duct. The measured spectra were obtained using an NE-213 liquid scintillator detector with pulse shape discrimination methods used to simultaneously resolve neutron and gamma ray events. The calculated spectra were obtained using a computer code network that incorporates two radiation transport methods: discrete ordinates (with P 3 multigroup cross sections) and Monte Carlo (with continuous point cross sections). The two radiation transport methods are required to account for neutrons that singly scatter from the duct to the detectors. The calculated and measured neutron energy spectra above 850 keV agree with 5 to 50% depending on detector location and neutron energy. The calculated and measured gamma ray energy spectra above 750 keV are also in favorable agreement, approx. 5 to 50%, depending on detector location and gamma ray energy

  14. Electronic Absorption Spectra of Neutral Perylene (C20H12), Terrylene (C30H16), and Quaterrylene (C40H20) and their Positive and Negative Ions: Ne Matrix-Isolation Spectroscopy and Time Dependent Density Functional Theory Calculations

    Science.gov (United States)

    Halasinski, Thomas M.; Weisman, Jennifer L.; Lee, Timothy J.; Salama, Farid; Head-Gordon, Martin; Kwak, Dochan (Technical Monitor)

    2002-01-01

    We present a full experimental and theoretical study of an interesting series of polycyclic aromatic hydrocarbons, the oligorylenes. The absorption spectra of perylene, terrylene and quaterrylene in neutral, cationic and anionic charge states are obtained by matrix-isolation spectroscopy in Ne. The experimental spectra are dominated by a bright state that red shifts with growing molecular size. Excitation energies and state symmetry assignments are supported by calculations using time dependent density functional theory methods. These calculations also provide new insight into the observed trends in oscillator strength and excitation energy for the bright states: the oscillator strength per unit mass of carbon increases along the series.

  15. Correcting for variable laser-target distances of laser-induced breakdown spectroscopy measurements with ChemCam using emission lines of Martian dust spectra

    Energy Technology Data Exchange (ETDEWEB)

    Melikechi, N.; Mezzacappa, A. [Optical Science Center for Applied Research, Delaware State University, Dover, DE (United States); Cousin, A.; Lanza, N.L. [Los Alamos National Laboratory, Los Alamos, NM (United States); Lasue, J. [Institut de Recherche en Astophysique et Planetologie (IRAP), Universite' Paul Sabatier, Toulouse (France); Clegg, S.M. [Los Alamos National Laboratory, Los Alamos, NM (United States); Berger, G. [Institut de Recherche en Astophysique et Planetologie (IRAP), Universite' Paul Sabatier, Toulouse (France); Wiens, R.C. [Los Alamos National Laboratory, Los Alamos, NM (United States); Maurice, S. [Institut de Recherche en Astophysique et Planetologie (IRAP), Universite' Paul Sabatier, Toulouse (France); Tokar, R.L.; Bender, S. [Planetary Science Institute, Flagstaff, AZ (United States); Forni, O. [Institut de Recherche en Astophysique et Planetologie (IRAP), Universite' Paul Sabatier, Toulouse (France); Breves, E.A.; Dyar, M.D. [Dept. of Astronomy, Mount Holyoke College, South Hadley, MA (United States); Frydenvang, J. [The Niels Bohr Institute, University of Copenhagen, Copenhagen (Denmark); Delapp, D. [Los Alamos National Laboratory, Los Alamos, NM (United States); Gasnault, O. [Institut de Recherche en Astophysique et Planetologie (IRAP), Universite' Paul Sabatier, Toulouse (France); Newsom, H.; Ollila, A.M. [Earth and Planetary Sciences, University of New Mexico, Alburquerque, NM (United States); Lewin, E. [Institut des Sciences de la Terre, Universite Grenoble l-CNRS, Grenoble (France); and others

    2014-06-01

    As part of the Mars Science Laboratory, the ChemCam instrument acquires remote laser induced breakdown spectra at distances that vary between 1.56 m and 7 m. This variation in distance affects the intensities of the measured LIBS emission lines in non-trivial ways. To determine the behavior of a LIBS emission line with distance, it is necessary to separate the effects of many parameters such as laser energy, laser spot size, target homogeneity, and optical collection efficiency. These parameters may be controlled in a laboratory on Earth but for field applications or in space this is a challenge. In this paper, we show that carefully selected ChemCam LIBS emission lines acquired from the Martian dust can be used to build an internal proxy spectroscopic standard. This in turn, allows for a direct measurement of the effects of the distance of various LIBS emission lines and hence can be used to correct ChemCam LIBS spectra for distance variations. When tested on pre-launch LIBS calibration data acquired under Martian-like conditions and with controlled and well-calibrated targets, this approach yields much improved agreement between targets observed at various distances. This work lays the foundation for future implementation of automated routines to correct ChemCam spectra for differences caused by variable distance. - Highlights: • Selected Martian dust emission lines are used to correct for variable laser-target distances. • The correction model yields improved agreement between targets observed at various distances. • The impact of the model reduces the bias between predicted and actual compositions by as much as 70%. • When implemented, the model will yield spectral corrections for various ChemCam measurements. • This work is a foundation to perform novel stand-off LIBS measurements on Earth and other planets.

  16. Theoretical investigation of the broad one-photon absorption line-shape of a flexible symmetric carbazole derivative.

    Science.gov (United States)

    Liu, Yanli; Cerezo, Javier; Santoro, Fabrizio; Rizzo, Antonio; Lin, Na; Zhao, Xian

    2016-08-17

    The one-photon absorption spectrum of a carbazole derivative has been studied by employing density functional response theory combined with a mixed quantum/classical (QC) approach to simulate the spectral shape. In a first step of our analysis we employed the vertical gradient (VG) vibronic model to investigate the role of Franck-Condon (FC) profiles of the first ten electronic excited states of the system, underlying most of the range of the experimental spectrum. We then focussed on the first six excited states covering the low-energy region of the spectrum, and investigated the effect of inter-state electronic couplings on the spectral shapes within Herzberg-Teller (HT) theory. Furthermore, in order to introduce the broadening effects due to the two inter-ring torsions, we employed a QC approach, adopting VG vibronic models for high-frequency modes and computing the contribution of the torsions to the spectrum from the distribution of the excitation energies along a two-dimensional relaxed potential energy. Finally, we estimated the solvent inhomogeneous broadening by computing the solvent reorganization energy using a polarizable continuum model. Our calculations allow us to obtain a non-phenomenological description of the low-energy part of the spectrum in semi-quantitative agreement with experiment and to dissect the relative importance of solvent, torsional flexibility, FC vibronic progressions, and inter-state couplings in determining its broad spectral shapes and the modulation of its intensity. Our analysis also clearly highlights that the investigated carbazole represents a big challenge for available methodologies due to the existence of many close-lying excited electronic states coupled by internal low-frequency and high-frequency motions and by solvent fluctuations. The study of their impact on the spectra at the HT level is only approximate and more refined treatments would require a fully quantum-dynamical calculation on the manifold of the coupled

  17. Oscillator strengths for absorption spectra of Pr/sup 3 +/, Nd/sup 3 +/, Eu/sup 3 +/, Er/sup 3 +/ and Yb/sup 3 +/ ions in GaCl/sub 3/-SOCl/sub 2/

    Energy Technology Data Exchange (ETDEWEB)

    Batyaev, I.M.; Shilov, S.M.

    1984-07-01

    The solutions of Pr/sup 3 +/, ND/sup 3 +/, Eu/sup 3 +/, Er/sup 3 +/, and Yb/sup 3 +/ chlorides in the aprotic inorganic solvent GaCl/sub 3/-SOCl/sub 2/ are prepared. The absorption spectra in the range 5000-24000 cm/sup -1/ are measured. In general, the correlation between the calculated (on the basis of Judd-Ofelt theory) and observed intensities in the solution absorption spectra is very good. The variation of the intensity parameters tausub(lambda) (where tausub(lambda)-values describing radial wave functions state, refrective index of a medium and ligand field parameters which is characteristic to the vicinity of rare-earth metal ions) over the series is discussed.

  18. Effect of different precursors on generation of reference spectra for structural molecular background correction by solid sampling high-resolution continuum source graphite furnace atomic absorption spectrometry: Determination of antimony in cosmetics.

    Science.gov (United States)

    Barros, Ariane Isis; Victor de Babos, Diego; Ferreira, Edilene Cristina; Gomes Neto, José Anchieta

    2016-12-01

    Different precursors were evaluated for the generation of reference spectra and correction of the background caused by SiO molecules in the determination of Sb in facial cosmetics by high-resolution continuum source graphite furnace atomic absorption spectrometry employing direct solid sample analysis. Zeolite and mica were the most effective precursors for background correction during Sb determination using the 217.581nm and 231.147nm lines. Full 2 3 factorial design and central composite design were used to optimize the atomizer temperature program. The optimum pyrolysis and atomization temperatures were 1500 and 2100°C, respectively. A Pd(NO 3 ) 2 /Mg(NO 3 ) 2 mixture was employed as the chemical modifier, and calibration was performed at 217.581nm with aqueous standards containing Sb in the range 0.5-2.25ng, resulting in a correlation coefficient of 0.9995 and a slope of 0.1548s ng -1 . The sample mass was in the range 0.15-0.25mg. The accuracy of the method was determined by analysis of Montana Soil (II) certified reference material, together with addition/recovery tests. The Sb concentration found was in agreement with the certified value, at a 95% confidence level (paired t-test). Recoveries of Sb added to the samples were in the range 82-108%. The limit of quantification was 0.9mgkg -1 and the relative standard deviation (n=3) ranged from 0.5% to 7.1%. From thirteen analyzed samples, Sb was not detected in ten samples (blush, eye shadow and compact powder); three samples (two blush and one eye shadow) presented Sb concentration in the 9.1-14.5mgkg -1 range. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. The effect of, within the sphere confined, particle diffusion on the line shape of incoherent cold neutron scattering spectra

    International Nuclear Information System (INIS)

    Cvikl, B.; Dahlborg, U.; Calvo-Dahlborg, M.

    1999-01-01

    Based upon the model of particles diffusion within the sphere of partially absorbing boundaries, the possibilities of the detection, by the incoherent cold neutron scattering method, of particle precipitation on the boundary walls, has been investigated. The calculated scattering law as a function of the boundary absorption properties exhibits distinct characteristic which might, under favorable conditions, make such an experimental attempt feasible.(author)

  20. Inner-shell X-ray line spectra of highly ionized titanium, chromium, iron and nickel and their application to laboratory plasmas

    International Nuclear Information System (INIS)

    Lemen, J.R.; Phillips, K.J.H.; Doschek, G.A.; Cowan, R.D.

    1986-06-01

    The intensities of X-ray lines due to inner-shell 1s-2p transitions in 0 I-, N I-, and C I-like ions of Ti XV-XVII, Cr XVII-XIX, Fe XIX-XXI, and Ni XXI-XXIII, seen in tokamak plasmas are calculated. The lines are assumed to be formed by dielectronic recombination and inner-shell excitation. The dielectronic rates were calculated using a suite of computer programs developed by one of the authors. The inner-shell contribution was estimated by van Regemorter's formula. The present calculations were applied to the problem of radial ion diffusion in tokamaks. Spectra were calculated by integrating along various lines-of-sight to simulate what might be observed by an actual spectrometer viewing a tokamak plasma. A method for determining the diffusion coefficient from tokamak observations is discussed. (author)