WorldWideScience

Sample records for absorption line indices

  1. Photoionization-driven Absorption-line Variability in Balmer Absorption Line Quasar LBQS 1206+1052

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Luming; Zhou, Hongyan; Ji, Tuo; Jiang, Peng; Liu, Bo; Pan, Xiang; Shi, Xiheng; Zhang, Shaohua [Polar Research Institute of China, 451 Jinqiao Road, Shanghai (China); Liu, Wenjuan; Wang, Jianguo [Yunnan Observatories, Chinese Academy of Sciences, Kunming, Yunnan (China); Wang, Tinggui; Yang, Chenwei [Department of Astronomy, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui (China); Miller, Lauren P., E-mail: lmsun@mail.ustc.edu.cn [Lehigh University, 27 Memorial Drive West, Bethlehem, PA 18015 (United States)

    2017-04-01

    In this paper we present an analysis of absorption-line variability in mini-BAL quasar LBQS 1206+1052. The Sloan Digital Sky Survey spectrum demonstrates that the absorption troughs can be divided into two components of blueshift velocities of ∼700 and ∼1400 km s{sup −1} relative to the quasar rest frame. The former component shows rare Balmer absorption, which is an indicator of high-density absorbing gas; thus, the quasar is worth follow-up spectroscopic observations. Our follow-up optical and near-infrared spectra using MMT, YFOSC, TSpec, and DBSP reveal that the strengths of the absorption lines vary for both components, while the velocities do not change. We reproduce all of the spectral data by assuming that only the ionization state of the absorbing gas is variable and that all other physical properties are invariable. The variation of ionization is consistent with the variation of optical continuum from the V -band light curve. Additionally, we cannot interpret the data by assuming that the variability is due to a movement of the absorbing gas. Therefore, our analysis strongly indicates that the absorption-line variability in LBQS 1206+1052 is photoionization driven. As shown from photoionization simulations, the absorbing gas with blueshift velocity of ∼700 km s{sup −1} has a density in the range of 10{sup 9} to 10{sup 10} cm{sup −3} and a distance of ∼1 pc, and the gas with blueshift velocity of ∼1400 km s{sup −1} has a density of 10{sup 3} cm{sup −3} and a distance of ∼1 kpc.

  2. 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.)

  3. 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

  4. 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

  5. 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.

  6. 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

  7. 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.

  8. 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.

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

    Directory of Open Access Journals (Sweden)

    Damien Hutsemékers

    2017-09-01

    Full Text Available 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.

  10. 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).

  11. 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.

  12. 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.

  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. STAR CLUSTERS IN M31. IV. A COMPARATIVE ANALYSIS OF ABSORPTION LINE INDICES IN OLD M31 AND MILKY WAY CLUSTERS

    International Nuclear Information System (INIS)

    Schiavon, Ricardo P.; Caldwell, Nelson; Morrison, Heather; Harding, Paul; Courteau, Stéphane; MacArthur, Lauren A.; Graves, Genevieve J.

    2012-01-01

    We present absorption line indices measured in the integrated spectra of globular clusters both from the Galaxy and from M31. Our samples include 41 Galactic globular clusters, and more than 300 clusters in M31. The conversion of instrumental equivalent widths into the Lick system is described, and zero-point uncertainties are provided. Comparison of line indices of old M31 clusters and Galactic globular clusters suggests an absence of important differences in chemical composition between the two cluster systems. In particular, CN indices in the spectra of M31 and Galactic clusters are essentially consistent with each other, in disagreement with several previous works. We reanalyze some of the previous data, and conclude that reported CN differences between M31 and Galactic clusters were mostly due to data calibration uncertainties. Our data support the conclusion that the chemical compositions of Milky Way and M31 globular clusters are not substantially different, and that there is no need to resort to enhanced nitrogen abundances to account for the optical spectra of M31 globular clusters.

  15. STAR CLUSTERS IN M31. IV. A COMPARATIVE ANALYSIS OF ABSORPTION LINE INDICES IN OLD M31 AND MILKY WAY CLUSTERS

    Energy Technology Data Exchange (ETDEWEB)

    Schiavon, Ricardo P. [Gemini Observatory, Hilo, HI 96720 (United States); Caldwell, Nelson [Smithsonian Astrophysical Observatory, Cambridge, MA 02138 (United States); Morrison, Heather; Harding, Paul [Department of Astronomy, Case Western Reserve University, Cleveland, OH 44106-7215 (United States); Courteau, Stephane [Department of Physics, Engineering Physics and Astronomy, Queen' s University, Kingston, ON K7L 3N6 (Canada); MacArthur, Lauren A. [Herzberg Institute of Astrophysics, National Research Council of Canada/University of Victoria, Victoria, B.C. V9E 2E7 (Canada); Graves, Genevieve J., E-mail: rschiavon@gemini.edu, E-mail: caldwell@cfa.harvard.edu, E-mail: paul.harding@case.edu, E-mail: heather@vegemite.case.edu, E-mail: courteau@astro.queensu.ca, E-mail: Lauren.MacArthur@nrc-cnrc.gc.ca, E-mail: graves@astro.berkeley.edu [Department of Astronomy, University of California, Berkeley, CA 94720 (United States)

    2012-01-15

    We present absorption line indices measured in the integrated spectra of globular clusters both from the Galaxy and from M31. Our samples include 41 Galactic globular clusters, and more than 300 clusters in M31. The conversion of instrumental equivalent widths into the Lick system is described, and zero-point uncertainties are provided. Comparison of line indices of old M31 clusters and Galactic globular clusters suggests an absence of important differences in chemical composition between the two cluster systems. In particular, CN indices in the spectra of M31 and Galactic clusters are essentially consistent with each other, in disagreement with several previous works. We reanalyze some of the previous data, and conclude that reported CN differences between M31 and Galactic clusters were mostly due to data calibration uncertainties. Our data support the conclusion that the chemical compositions of Milky Way and M31 globular clusters are not substantially different, and that there is no need to resort to enhanced nitrogen abundances to account for the optical spectra of M31 globular clusters.

  16. A SURVEY OF ALKALI LINE ABSORPTION IN EXOPLANETARY ATMOSPHERES

    International Nuclear Information System (INIS)

    Jensen, Adam G.; Redfield, Seth; Endl, Michael; Cochran, William D.; Koesterke, Lars; Barman, Travis S.

    2011-01-01

    We obtained over 90 hr of spectroscopic observations of four exoplanetary systems with the Hobby-Eberly Telescope. Observations were taken in transit and out of transit, and we analyzed the differenced spectra—i.e., the transmission spectra—to inspect it for absorption at the wavelengths of the neutral sodium (Na I) doublet at λλ5889, 5895 and neutral potassium (K I) at λ7698. We used the transmission spectrum at Ca I λ6122—which shows strong stellar absorption but is not an alkali metal resonance line that we expect to show significant absorption in these atmospheres—as a control line to examine our measurements for systematic errors. We use an empirical Monte Carlo method to quantify these systematic errors. In a reanalysis of the same data set using a reduction and analysis pipeline that was derived independently, we confirm the previously seen Na I absorption in HD 189733b at a level of (– 5.26 ± 1.69) × 10 –4 (the average value over a 12 Å integration band to be consistent with previous authors). Additionally, we tentatively confirm the Na I absorption seen in HD 209458b (independently by multiple authors) at a level of (– 2.63 ± 0.81) × 10 –4 , though the interpretation is less clear. Furthermore, we find Na I absorption of (– 3.16 ± 2.06) × 10 –4 at <3σ in HD 149026b; features apparent in the transmission spectrum are consistent with real absorption and indicate this may be a good target for future observations to confirm. No other results (Na I in HD 147506b and Ca I and K I in all four targets) are significant to ≥3σ, although we observe some features that we argue are primarily artifacts.

  17. 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.

  18. 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.

  19. 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.

  20. Temperature-insensitive laser frequency locking near absorption lines

    International Nuclear Information System (INIS)

    Kostinski, Natalie; Olsen, Ben A.; Marsland, Robert III; McGuyer, Bart H.; Happer, William

    2011-01-01

    Combined magnetically induced circular dichroism and Faraday rotation of an atomic vapor are used to develop a variant of the dichroic atomic vapor laser lock that eliminates lock sensitivity to temperature fluctuations of the cell. Operating conditions that eliminate first-order sensitivity to temperature fluctuations can be determined by low-frequency temperature modulation. This temperature-insensitive gyrotropic laser lock can be accurately understood with a simple model, that is in excellent agreement with observations in potassium vapor at laser frequencies in a 2 GHz range about the 770.1 nm absorption line. The methods can be readily adapted for other absorption lines.

  1. 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

  2. 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...

  3. Absorption of aluminium X-ray lines in a laser created gold plasma

    International Nuclear Information System (INIS)

    Combis, P.; Busquet, M.; Louis-Jacquet, M.

    1986-04-01

    We have studied the absorption of aluminium X-ray lines through a gold plasma by focusing a high intensity laser-beam onto a specific target. Absorption in the wavelength range of 5 to 7 A has been evidenced and measured for Aluminium resonance lines

  4. Integrated Spectral Energy Distributions and Absorption Feature Indices of Single Stellar Populations

    OpenAIRE

    Zhang, Fenghui; Han, Zhanwen; Li, Lifang; Hurley, Jarrod R.

    2004-01-01

    Using evolutionary population synthesis, we present integrated spectral energy distributions and absorption-line indices defined by the Lick Observatory image dissector scanner (referred to as Lick/IDS) system, for an extensive set of instantaneous burst single stellar populations (SSPs). The ages of the SSPs are in the range 1-19 Gyr and the metallicities [Fe/H] are in the range -2.3 - 0.2. Our models use the rapid single stellar evolution algorithm of Hurley, Pols and Tout for the stellar e...

  5. Experimental determination of line strengths for selected carbon monoxide and carbon dioxide absorption lines at temperatures between 295 and 1250 K

    International Nuclear Information System (INIS)

    Medvecz, P.J.; Nichols, K.M.

    1994-01-01

    Fourier transform infrared absorption spectroscopy has been used for the determination of the line strengths of 41 CO and CO 2 absorption lines at temperatures between 295 and 1250 K. The CO vibrational-rotational lines were from the P branch of the fundamental absorption band (2150--1950 cm -1 ) while the CO 2 vibrational-rotational lines were from the far wing of the R branch of the ν 3 fundamental band (2395--2380 cm -1 ). The intensities of the lines were measured from absorption spectra recorded in a high-temperature gas cell containing known concentrations of CO/CO 2 /N 2 gas mixtures at atmospheric pressure. Absorption spectra were recorded through the cell with the use of a moderate-resolution Fourier transform infrared spectrometer. The absorption spectra were mathematically corrected for distortions resulting from the finite resolution of the spectrometer and for peak overlap. Line strength measurements were made from the corrected peaks by using the Bouguer-Lambert law and assuming a Lorentzian line profile. The experimentally obtained line strengths were evaluated by statistical calculations, by consideration of the validity of the Bouguer-Lambert assumption for these data, by comparison with existing room-temperature and high-temperature data, and by comparison with theoretical calculations. For CO, the statistical analysis suggests that the reported values have an uncertainty of ±10--12%, which is similar to the observed discrepancies with other reported values at room temperature. At high temperatures, the difference between these data and previously reported data and theoretical predictions is less than 10%. For CO 2 , the statistical uncertainty associated with the line strength calculations is less than 5%, which is also the approximate level of agreement with existing room-temperature data

  6. The Mean Metal-line Absorption Spectrum of Damped Ly α Systems in BOSS

    Energy Technology Data Exchange (ETDEWEB)

    Mas-Ribas, Lluís [Institute of Theoretical Astrophysics, University of Oslo, Postboks 1029, NO-0315 Oslo (Norway); Miralda-Escudé, Jordi; Pérez-Ràfols, Ignasi; Arinyo-i-Prats, Andreu [Institut de Ciències del Cosmos, Universitat de Barcelona (UB-IEEC), Barcelona E-08028, Catalonia (Spain); Noterdaeme, Pasquier; Petitjean, Patrick [Institut d’Astrophysique de Paris, UPMC and CNRS, UMR7095 98bis Boulevard Arago, F-75014—Paris (France); Schneider, Donald P. [Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States); York, Donald G. [Department of Astronomy and Astrophysics and the Enrico Fermi Institute, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Ge, Jian, E-mail: l.m.ribas@astro.uio.no [Department of Astronomy, University of Florida, Bryant Space Science Center, Gainesville, FL 32611-2055 (United States)

    2017-09-01

    We study the mean absorption spectrum of the Damped Ly α (DLA) population at z ∼ 2.6 by stacking normalized, rest-frame-shifted spectra of ∼27,000 DLA systems from the DR12 of the Baryon Oscillation Spectroscopic Survey (BOSS)/SDSS-III. We measure the equivalent widths of 50 individual metal absorption lines in five intervals of DLA hydrogen column density, five intervals of DLA redshift, and overall mean equivalent widths for an additional 13 absorption features from groups of strongly blended lines. The mean equivalent width of low-ionization lines increases with N {sub H} {sub i}, whereas for high-ionization lines the increase is much weaker. The mean metal line equivalent widths decrease by a factor ∼1.1–1.5 from z ∼ 2.1 to z ∼ 3.5, with small or no differences between low- and high-ionization species. We develop a theoretical model, inspired by the presence of multiple absorption components observed in high-resolution spectra, to infer mean metal column densities from the equivalent widths of partially saturated metal lines. We apply this model to 14 low-ionization species and to Al iii, S iii, Si iii, C iv, Si iv, N v, and O vi. We use an approximate derivation for separating the equivalent width contributions of several lines to blended absorption features, and infer mean equivalent widths and column densities from lines of the additional species N i, Zn ii, C ii*, Fe iii, and S iv. Several of these mean column densities of metal lines in DLAs are obtained for the first time; their values generally agree with measurements of individual DLAs from high-resolution, high signal-to-noise ratio spectra when they are available.

  7. Outflow and hot dust emission in broad absorption line quasars

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Shaohua; Zhou, Hongyan [Polar Research Institute of China, 451 Jinqiao Road, Shanghai 200136 (China); Wang, Huiyuan; Wang, Tinggui; Xing, Feijun; Jiang, Peng [Key Laboratory for Research in Galaxies and Cosmology, University of Science and Technology of China, Chinese Academy of Sciences, Hefei, Anhui 230026 (China); Zhang, Kai, E-mail: zhangshaohua@pric.gov.cn, E-mail: whywang@mail.ustc.edu.cn [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China)

    2014-05-01

    We have investigated a sample of 2099 broad absorption line (BAL) quasars with z = 1.7-2.2 built from the Sloan Digital Sky Survey Data Release Seven and the Wide-field Infrared Survey. This sample is collected from two BAL quasar samples in the literature and is refined by our new algorithm. Correlations of outflow velocity and strength with a hot dust indicator (β{sub NIR}) and other quasar physical parameters—such as an Eddington ratio, luminosity, and a UV continuum slope—are explored in order to figure out which parameters drive outflows. Here β{sub NIR} is the near-infrared continuum slope, which is a good indicator of the amount of hot dust emission relative to the accretion disk emission. We confirm previous findings that outflow properties moderately or weakly depend on the Eddington ratio, UV slope, and luminosity. For the first time, we report moderate and significant correlations of outflow strength and velocity with β{sub NIR} in BAL quasars. It is consistent with the behavior of blueshifted broad emission lines in non-BAL quasars. The statistical analysis and composite spectra study both reveal that outflow strength and velocity are more strongly correlated with β{sub NIR} than the Eddington ratio, luminosity, and UV slope. In particular, the composites show that the entire C IV absorption profile shifts blueward and broadens as β{sub NIR} increases, while the Eddington ratio and UV slope only affect the high and low velocity part of outflows, respectively. We discuss several potential processes and suggest that the dusty outflow scenario, i.e., that dust is intrinsic to outflows and may contribute to the outflow acceleration, is most likely.

  8. Narrow absorption lines with two observations from the Sloan Digital Sky Survey

    Science.gov (United States)

    Chen, Zhi-Fu; Gu, Qiu-Sheng; Chen, Yan-Mei; Cao, Yue

    2015-07-01

    We assemble 3524 quasars from the Sloan Digital Sky Survey (SDSS) with repeated observations to search for variations of the narrow C IV λ λ 1548,1551 and Mg II λ λ 2796,2803 absorption doublets in spectral regions shortward of 7000 Å in the observed frame, which corresponds to time-scales of about 150-2643 d in the quasar rest frame. In these quasar spectra, we detect 3580 C IV absorption systems with zabs = 1.5188-3.5212 and 1809 Mg II absorption systems with zabs = 0.3948-1.7167. In term of the absorber velocity (β) distribution in the quasar rest frame, we find a substantial number of C IV absorbers with β Hacker et al. However, in our Mg II absorption sample, we find that neither shows variable absorption with confident levels of >4σ for λ2796 lines and >3σ for λ2803 lines.

  9. 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.

  10. 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.

  11. 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

  12. Anomaly in shape of resonance absorption lines of atoms with large fine-structure splitting of levels

    International Nuclear Information System (INIS)

    Parkhomenko, A.I.; yachev, S.P."" >Podyachev, S.P.; Privalov, T.I.; Shalagin, A.M.

    1997-01-01

    Absorption line of monochromatic radiation by atoms nonselective excitation by velocities under conditions of optical excitation of components of superfine structure of the basic electron state is considered. It is shown that the absorption line has unusual substructures for certain values of the basic state superfine desintegration. These substructures in the absorption spectrum may be pointed out by accounting the superfine structure of the electron excited state. The absorption spectra of monochromatic radiation close tot he D 1 - and D 2 -lines of the atomic rubidium are calculated

  13. Conduction noise absorption by ITO thin films attached to microstrip line utilizing Ohmic loss

    International Nuclear Information System (INIS)

    Kim, Sun-Hong; Kim, Sung-Soo

    2010-01-01

    For the aim of wide-band noise absorbers with a special design for low frequency performance, this study proposes conductive indium-tin oxide (ITO) thin films as the absorbent materials in microstrip line. ITO thin films were deposited on the polyimide film substrates by rf magnetron cosputtering of In 2 O 3 and Sn targets. The deposited ITO films show a typical value of electrical resistivity (∼10 -4 Ω m) and sheet resistance can be controlled in the range of 20-230 Ω by variation in film thickness. Microstrip line with characteristic impedance of 50 Ω was used for determining their noise absorbing properties. It is found that there is an optimum sheet resistance of ITO films for the maximum power absorption. Reflection parameter (S 11 ) is increased with decrease in sheet resistance due to impedance mismatch. On the while, transmission parameter (S 21 ) is decreased with decrease in sheet resistance due to larger Ohmic loss of the ITO films. Experimental results and computational prediction show that the optimum sheet resistance is about 100 Ω. For this film, greater power absorption is predicted in the lower frequency region than ferrite thin films of high magnetic loss, which indicates that Ohmic loss is the predominant loss parameter for power absorption in the low frequency range.

  14. 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.

  15. 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 ...

  16. THE SLOAN DIGITAL SKY SURVEY REVERBERATION MAPPING PROJECT: RAPID C iv BROAD ABSORPTION LINE VARIABILITY

    International Nuclear Information System (INIS)

    Grier, C. J.; Brandt, W. N.; Trump, J. R.; Schneider, D. P.; Hall, P. B.; Shen, Yue; Vivek, M.; Dawson, K. S.; Ak, N. Filiz; Chen, Yuguang; Denney, K. D.; Kochanek, C. S.; Peterson, B. M.; Green, Paul J.; Jiang, Linhua; McGreer, Ian D.; Pâris, I.; Tao, Charling; Wood-Vasey, W. M.; Bizyaev, Dmitry

    2015-01-01

    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 −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 e ≳ 3.9 × 10 5 cm −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

  17. Selection of the optimal combination of water vapor absorption lines for detection of temperature in combustion zones of mixing supersonic gas flows by diode laser absorption spectrometry

    International Nuclear Information System (INIS)

    Mironenko, V.R.; Kuritsyn, Yu.A.; Bolshov, M.A.; Liger, V.V.

    2017-01-01

    Determination of a gas medium temperature by diode laser absorption spectrometry (DLAS) is based on the measurement of integral intensities of the absorption lines of a test molecule (generally water vapor molecule). In case of local thermodynamic equilibrium temperature is inferred from the ratio of the integral intensities of two lines with different low energy levels. For the total gas pressure above 1 atm the absorption lines are broadened and one cannot find isolated well resolved water vapor absorption lines within relatively narrow spectral interval of fast diode laser (DL) tuning range (about 3 cm"−"1). For diagnostics of a gas object in the case of high temperature and pressure DLAS technique can be realized with two diode lasers working in different spectral regions with strong absorption lines. In such situation the criteria of the optimal line selection differs significantly from the case of narrow lines. These criteria are discussed in our work. The software for selection the optimal spectral regions using the HITRAN-2012 and HITEMP data bases is developed. The program selects spectral regions of DL tuning, minimizing the error of temperature determination δT/T, basing on the attainable experimental error of line intensity measurement δS. Two combinations of optimal spectral regions were selected – (1.392 & 1.343 μm) and (1.392 & 1.339 μm). Different algorithms of experimental data processing are discussed.

  18. X-RAYS FROM A RADIO-LOUD COMPACT BROAD ABSORPTION LINE QUASAR 1045+352 AND THE NATURE OF OUTFLOWS IN RADIO-LOUD BROAD ABSORPTION LINE QUASARS

    International Nuclear Information System (INIS)

    Kunert-Bajraszewska, Magdalena; Katarzynski, Krzysztof; Siemiginowska, Aneta; Janiuk, Agnieszka

    2009-01-01

    We present new results on X-ray properties of radio-loud broad absorption line (BAL) quasars and focus on broadband spectral properties of a high-ionization BAL (HiBAL) compact steep spectrum (CSS) radio-loud quasar 1045+352. This HiBAL quasar has a very complex radio morphology indicating either strong interactions between a radio jet and the surrounding interstellar medium or a possible re-start of the jet activity. We detected 1045+352 quasar in a short 5 ksec Chandra ACIS-S observation. We applied theoretical models to explain spectral energy distribution of 1045+352 and argue that non-thermal, inverse-Compton (IC) emission from the innermost parts of the radio jet can account for a large fraction of the observed X-ray emission. In our analysis, we also consider a scenario in which the observed X-ray emission from radio-loud BAL quasars can be a sum of IC jet X-ray emission and optically thin corona X-ray emission. We compiled a sample of radio-loud BAL quasars that were observed in X-rays to date and report no correlation between their X-ray and radio luminosity. However, the radio-loud BAL quasars show a large range of X-ray luminosities and absorption columns. This is consistent with the results obtained earlier for radio-quiet BAL quasars and may indicate an orientation effect in BAL quasars or more complex dependence between X-ray emission, radio emission, and an orientation based on the radio morphology.

  19. Thomson Thick X-Ray Absorption in a Broad Absorption Line Quasar, PG 0946+301.

    Science.gov (United States)

    Mathur; Green; Arav; Brotherton; Crenshaw; deKool; Elvis; Goodrich; Hamann; Hines; Kashyap; Korista; Peterson; Shields; Shlosman; van Breugel W; Voit

    2000-04-20

    We present a deep ASCA observation of a broad absorption line quasar (BALQSO) PG 0946+301. The source was clearly detected in one of the gas imaging spectrometers, but not in any other detector. If BALQSOs have intrinsic X-ray spectra similar to normal radio-quiet quasars, our observations imply that there is Thomson thick X-ray absorption (NH greater, similar1024 cm-2) toward PG 0946+301. This is the largest column density estimated so far toward a BALQSO. The absorber must be at least partially ionized and may be responsible for attenuation in the optical and UV. If the Thomson optical depth toward BALQSOs is close to 1, as inferred here, then spectroscopy in hard X-rays with large telescopes like XMM would be feasible.

  20. 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.

  1. Testing Disk-Wind Models with Quasar CIV 1549Å Associated Absorption Lines

    DEFF Research Database (Denmark)

    Vestergaard, Marianne

    2012-01-01

    Narrow associated C IV 1549Å absorption lines (NALs) with a rest equivalent width EW =3 Å detected in z ˜ 2 radio-loud and radio-quiet quasars, (a) exhibit evidence of an origin in radiatively accelerated gas, and (b) may be closely related to broad absorption line (BAL) outflows. These NALs...... and the few BALs detected in this quasar sample obey key predictions of models of radiatively driven disk-winds in which (1) the local disk luminosity launches the wind, (2) the central UV radiation drives it outwards, and (3) the wind acceleration (i.e., terminal velocity) depends on the strength of the X...

  2. 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).

  3. An immortal cell line to study the role of endogenous CFTR in electrolyte absorption.

    Science.gov (United States)

    Bell, C L; Quinton, P M

    1995-01-01

    The intact human reabsorptive sweat duct (RD) has been a reliable model for investigations of the functional role of "endogenous" CFTR (cystic fibrosis transmembrane conductance regulator) in normal and abnormal electrolyte absorptive function. But to overcome the limitations imposed by the use of fresh, intact tissue, we transformed cultured RD cells using the chimeric virus Ad5/SV40 1613 ori-. The resultant cell line, RD2(NL), has remained differentiated forming a polarized epithelium that expressed two fundamental components of absorption, a cAMP activated Cl- conductance (GCl) and an amiloride-sensitive Na+ conductance (GNa). In the unstimulated state, there was a low level of transport activity; however, addition of forskolin (10(-5) M) significantly increased the Cl- diffusion potential (Vt) generated by a luminally directed Cl- gradient from -15.3 +/- 0.7 mV to -23.9 +/- 1.1 mV, n = 39; and decreased the transepithelial resistance (Rt) from 814.8 +/- 56.3 omega.cm2 to 750.5 +/- 47.5 omega.cm2, n = 39, (n = number of cultures). cAMP activation, anion selectivity (Cl- > I- > gluconate), and a dependence upon metabolic energy (metabolic poisoning inhibited GCl), all indicate that the GCl expressed in RD2(NL) is in fact CFTR-GCl. The presence of an apical amiloride-sensitive GNa was shown by the amiloride (10(-5) M) inhibition of GNa as indicated by a reduction of Vt and equivalent short circuit current by 78.0 +/- 3.1% and 77.9 +/- 2.6%, respectively, and an increase in Rt by 7.2 +/- 0.8%, n = 36. In conclusion, the RD2(NL) cell line presents the first model system in which CFTR-GCl is expressed in a purely absorptive tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

  4. Discovery of an X-ray Violently Variable Broad Absorption Line Quasar

    Science.gov (United States)

    Ghosh, Kajal K.; Gutierrez, Carlos M.; Punsly, Brian; Chevallier, Loic; Goncalves, Anabela C.

    2006-01-01

    In this letter, we report on a quasar that is violently variable in the X-rays, XVV. It is also a broad absorption line quasar (BALQSO) that exhibits both high ionization and low ionization UV absorption lines (LoBALQSO). It is very luminous in the X-rays (approximately 10(exp 46) ergs s(sup -l) over the entire X-ray band). Surprisingly, this does not over ionize the LoBAL outflow. The X-rays vary by a factor of two within minutes in the quasar rest frame, which is shorter than 1/30 of the light travel time across a scale length equal to the black hole radius. We concluded that the X-rays are produced in a relativistic jet beamed toward earth in which variations in the Doppler enhancement produce the XVV behavior.

  5. Line by Line CO2 Absorption in the Atmosphere for Input Data to Calculate Global Warming, David C. Smith, DCS Lasers & Optics LLC, Old Saybrook CT 06475

    Science.gov (United States)

    Smith, D. C.

    2012-12-01

    Compter modeling of global climate change require an input (asssumption) of the forcing function for CO2 absorption. All codes use a long term forcing function of ~ 4 W/M2. (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, Cambridge U. Press N.Y.)..This is based on a band model of the CO2 rotational/vibrational absorption where a band of absorption averages over all the rotational levels of the vibration transition. (Ramananathan,V.,et al, J. of Geophysical Research,Vol 84 C8,p4949,Aug.1979).. The model takes into account the line width,the spacing between lines and identifies 10 CO2 bands.. This approach neglects the possibility that the peak absorption transitions in a band can "use up" all of the earths IR radiation at that wavelength and does not contribute to global warming no matter how much the CO2 is increased. The lines in the wings of a band increase their absorption as the CO2 is increased. However, the lines that are lost are the strong absorbers and those that are added are the weaker absorption lines. When a band begins to use up the IR then the net result of increasing the atmospheric CO2 is a decrease in the absorption change. This presentation calculates the absorption of each line individualy using the Behr's Law Approach. The dependence of the absorption and line width of each transition as a function of altitude is accounted for. The temperature dependence of the absorption with altitude is not and an evaluation of this error is given. For doubling CO2 from 320ppm to 640 ppm, the calculation gives a forcing function of 1.1 W/M2. The results show the importance of using individual lines to calculate the CO2 contribution to global warming, We can speculate on the imact and anticipate a computer code calculation of a factor of 4 less global warming than the published results.

  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. 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.

  8. Narrow Quasar Absorption Lines and the History of the Universe

    Science.gov (United States)

    Liebscher, Dierck-Ekkehard

    In order to get an estimation of the parameters of the cosmological model the statistics of narrow absorption lines in quasar spectra is evaluated. To this end a phenomenological model of the evolution of the corresponding absorbers in density, size, number and dimension is presented and compared with the observed evolution in the spectral density of the lines and their column density seen in the equivalent width. In spite of the wide range of possible models, the Einstein-deSitter model is shown to be unlikely because of the implied fast evolution in mass.

  9. 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

  10. 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...

  11. Experimental design and methodology for a new Moessbauer scan experiment: absorption line tracking

    International Nuclear Information System (INIS)

    Veiga, A.; Pasquevich, G. A.; Zelis, P. Mendoza; Sanchez, F. H.; Fernandez van Raap, M. B.; Martinez, N.

    2009-01-01

    A new experimental setup and methodology that allows the automatic tracking of a Moessbauer absorption line as its energy position varies during the experiment is introduced. As a test the sixth spectral line of FeSn 2 was tracked while temperature was varied between room temperature and a value slightly above its Neel temperature.

  12. Using the Properties of Broad Absorption Line Quasars to Illuminate Quasar Structure

    Science.gov (United States)

    Yong, Suk Yee; King, Anthea L.; Webster, Rachel L.; Bate, Nicholas F.; O'Dowd, Matthew J.; Labrie, Kathleen

    2018-06-01

    A key to understanding quasar unification paradigms is the emission properties of broad absorption line quasars (BALQs). The fact that only a small fraction of quasar spectra exhibit deep absorption troughs blueward of the broad permitted emission lines provides a crucial clue to the structure of quasar emitting regions. To learn whether it is possible to discriminate between the BALQ and non-BALQ populations given the observed spectral properties of a quasar, we employ two approaches: one based on statistical methods and the other supervised machine learning classification, applied to quasar samples from the Sloan Digital Sky Survey. The features explored include continuum and emission line properties, in particular the absolute magnitude, redshift, spectral index, line width, asymmetry, strength, and relative velocity offsets of high-ionisation C IV λ1549 and low-ionisation Mg II λ2798 lines. We consider a complete population of quasars, and assume that the statistical distributions of properties represent all angles where the quasar is viewed without obscuration. The distributions of the BALQ and non-BALQ sample properties show few significant differences. None of the observed continuum and emission line features are capable of differentiating between the two samples. Most published narrow disk-wind models are inconsistent with these observations, and an alternative disk-wind model is proposed. The key feature of the proposed model is a disk-wind filling a wide opening angle with multiple radial streams of dense clumps.

  13. Determination numbers of ionized atoms from emission and absorption lines

    International Nuclear Information System (INIS)

    Alizadeh Azimi, A.; Shokouhi, N.

    2002-01-01

    Saha, M., (1920) estimated that salter chromosphere is not only due to radiation from neutral atoms, but from ionized atoms. The failure to observe these stellar lines in the laboratory was attributed to internal temperature and pressure about 10* E + 6 K 10* E-7 atm. In this research we found that emission lines of ionized atoms (like Cs) could be measured in laboratory condition, (about 10* E-3 atm and 2000 K) by using Graphite France Atomic Absorption with injection 124 u g C sel. We calculated the numbers of ionized atoms from Bottzman law. We also measured these numbers from area under the energy-time curve

  14. MISALIGNMENT OF THE JET AND THE NORMAL TO THE DUSTY TORUS IN THE BROAD ABSORPTION LINE QSO FIRST J155633.8+351758

    International Nuclear Information System (INIS)

    Reynolds, Cormac; Punsly, Brian; O'Dea, Christopher P.

    2013-01-01

    We performed Very Long Baseline Array observations of the broad absorption line quasar FIRST J155633.8+351758, ''the first radio loud BALQSO''. Our observations at 15.3 GHz partially resolved a secondary component at position angle (P.A.) ≈35°. We combine this determination of the radio jet projection on the sky plane, with the constraint that the jet is viewed within 14.°3 of the line of sight (as implied by the high variability brightness temperature) and with the P.A. of the optical/UV continuum polarization in order to study the quasar geometry. Within the context of the standard model, the data indicates a ''dusty torus'' (scattering surface) with a symmetry axis tilted relative to the accretion disk normal and a polar broad absorption line outflow aligned with the accretion disk normal. We compare this geometry to that indicated by the higher resolution radio data, brightness temperature, and optical/UV continuum polarization P.A. of a similar high optical polarization BALQSO, Mrk 231. A qualitatively similar geometry is found in these two polar BALQSOs; the continuum polarization is determined primarily by the tilt of the dusty torus

  15. 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)

  16. Spectro web: oscillator strength measurements of atomic absorption lines in the sun and procyon

    International Nuclear Information System (INIS)

    Lobel, A

    2008-01-01

    We update the online SpectroWeb database of spectral standard reference stars with 1178 oscillator strength values of atomic absorption lines observed in the optical spectrum of the Sun and Procyon (α CMi A). The updated line oscillator strengths are measured with best fits to the disk-integrated KPNO-FTS spectrum of the Sun observed between 4000 A and 6800 A using state-of-the-art detailed spectral synthesis calculations. A subset of 660 line oscillator strengths is validated with synthetic spectrum calculations of Procyon observed with ESO-UVES between 4700 A and 6800 A. The new log(gf)-values in SpectroWeb are improvements upon the values offered in the online Vienna Atomic Line Database (VALD). We find for neutral iron-group elements, such as Fe I, Ni I, Cr I, and Ti I, a statistically significant over-estimation of the VALD log((gf)-values for weak absorption lines with normalized central line depths below 15 %. For abundant lighter elements (e.g. Mg I and Ca I) this trend is statistically not significantly detectable, with the exception of Si I for which the log(gf)-values of 60 weak and medium-strong lines are substantially decreased to best fit the observed spectra. The newly measured log(gf)-values are available in the SpectroWeb database at http://spectra.freeshell.org, which interactively displays the observed and computed stellar spectra, together with corresponding atomic line data.

  17. 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,

  18. Infrared line intensities of chlorine monoxide

    Science.gov (United States)

    Kostiuk, T.; Faris, J. L.; Mumma, M. J.; Deming, D.; Hillman, J. J.

    1986-01-01

    Absolute infrared line intensities of several ClO lines in the rotational-vibrational (1-0) band were measured using infrared heterodyne spectroscopy near 12 microns. A measurement technique using combined ultraviolet absorption and infrared line measurements near 9.5 microns and 12 microns permitted an accurate determination of the column densities of O3 and ClO in the absorption cell and thus improved ClO line intensities. Results indicate ClO line and band intensities approximately 2.4 times lower than previous experimental results. Effects of possible failure of local thermodynamic equilibrium conditions in the absorption cell and the implication of the results for stratospheric ClO measurements in the infrared are discussed.

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

    International Nuclear Information System (INIS)

    Misawa, Toru; Charlton, Jane C.; Eracleous, Michael

    2014-01-01

    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 3 -10 5 cm –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.

  20. Optical and mechanical design of the extended x-ray absorption fine structure (EXAFS) beam-line at Indus-II synchrotron source

    International Nuclear Information System (INIS)

    Das, N.C.; Jha, S.N.; Bhattacharyya, D.; Sinha, A.K.; Mishra, V.K.; Verma, Vishnu; Ghosh, A.K.

    2002-11-01

    An extended x-ray absorption fine structure (EXAFS) beam line for x-ray absorption studies using energy dispersive geometry and position sensitive detector is being designed for the INDUS-II Synchrotron source. The beam line would be used for doing x-ray absorption experiments involving measurements of fme structures above the absorption edge of different species of atoms in a material The results of the above experiments would lead to the determination of different important structural parameters of materials viz.. inter-atomic distance. co-ordination number, degree of disorder and radial distribution function etc. The optical design of the beam line has been completed based on the working principle that a single crystal bent in the shape of an ellipse by a crystal bender would act as a dispersing as well as focusing element. The mechanical design of the beam line including the crystal bender has also been completed and discussed here. Calculations have been done to detennine the temperature profile on the different components of the beam line under exposure to synchrotron radiation and proper cooling channels have been designed to bring down the heat load on the components. (author)

  1. Cosmological Evolution of QSO Absorption Systems

    Science.gov (United States)

    Stengler-Larrea, Erik

    1995-08-01

    First, the evolution with cosmic time of the hydrogen clouds which produce the Lyman-alpha absorption lines is studied in dependence on the strength of these lines. From the analysis it is concluded that the results show no evidence of a dependence in the sense of stronger lines evolving faster, although for the resolution at which the used observations were done, it can not be ruled out. Within the same analysis, a distribution of the Doppler parameter of the lines was obtained, with large values and a wide spread. This parameter being an indicator of the gas temperature, this result is in accordance with high temperatures and, consequently, large ionised fractions and a large fraction of the baryonic matter of the universe being associated with these clouds. However, recent high resolution studies seem to reveal that much lower temperatures are characteristic of the clouds. The main content of this thesis, however, focuses on the redshift evolution of the absorbing systems producing absorption at the Lyman limit and of the amount of CIV producing CIV absorption lines. Regarding the CIV absorbers, previous predictions on the effects underlying their redshift distribution pointed to an increase with redshift of the absorbing column densities. In this thesis the first direct measurements of such column densities by profile fitting of a large number of absorption systems (73) are presented, confirming the predictions of a decrease of at least a factor of 3 between z=1.5 and z=3.0. The study on the evolution of Lyman limit absorption systems (LLSs) puts an end to previous discrepancies between the results of different groups. Both a smooth single power law dependence of the LLS number density on redshift indicating no evolution in number density for 0.4 Team of the HST Key Project on QSO absorption lines, and in particular to estimate the necessary exposure times, the magnitudes of several of these objects had to be re-measured. The acquisition of their images and the

  2. Direct absorption and transfer of cesium 137 in a simplified fresh water supply line

    International Nuclear Information System (INIS)

    Foulquier, L.; Grauby, A.; Lambrechts, A.

    1977-01-01

    Experimentally the transfer of Cesium 137 through the supply line: Daphnia Magna Straus→Lebistes Reticulatus Peters→Anguilla Anguilla L. starting from water at 50μCi/l is studied. In the direct transfer water→organisms, the three links used have a concentration factor comprised between 2 and 4. The organisms retain a maximum of 0,3% of the water's radioactivity. The muscular mass of the eel represents 60% of the animal's total activity. The biological period is close to 400 days indicating that the fixed Cesium is strongly retained. Through the absorption of a contaminated meal, the Lebists, after two days, retain 67% of the activities of the Daphnies and the Eels, after seven days, 39% of the activity of the Guppys. At the end of the experiment, the Eels contaminated by food 3.500. It takes 63 meals for the level of contamination due to food to equal that due to water. The concentration factors measured in situ are always distinctly higher than those obtained in the laboratory. The experiment proves the possibilities of concentration through the food supply line [fr

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

    Science.gov (United States)

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

    2002-01-01

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

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. NEW PERSPECTIVE ON GALAXY OUTFLOWS FROM THE FIRST DETECTION OF BOTH INTRINSIC AND TRAVERSE METAL-LINE ABSORPTION

    Energy Technology Data Exchange (ETDEWEB)

    Kacprzak, Glenn G.; Cooke, Jeff [Swinburne University of Technology, Victoria 3122 (Australia); Martin, Crystal L.; Ho, Stephanie H. [Physics Department, University of California, Santa Barbara, CA 93106 (United States); Bouché, Nicolas; LeReun, Audrey; Schroetter, Ilane [CNRS, Institut de Recherche en Astrophysique et Planétologie (IRAP) de Toulouse, 14 Avenue E. Belin, F-31400 Toulouse (France); Churchill, Christopher W.; Klimek, Elizabeth, E-mail: gkacprzak@astro.swin.edu.au [New Mexico State University, Las Cruces, NM 88003 (United States)

    2014-09-01

    We present the first observation of a galaxy (z = 0.2) that exhibits metal-line absorption back-illuminated by the galaxy (down-the-barrel) and transversely by a background quasar at a projected distance of 58 kpc. Both absorption systems, traced by Mg II, are blueshifted relative to the galaxy systemic velocity. The quasar sight line, which resides almost directly along the projected minor axis of the galaxy, probes Mg I and Mg II absorption obtained from the Keck/Low Resolution Imaging Spectrometer as well as Lyα, Si II, and Si III absorption obtained from the Hubble Space Telescope/Cosmic Origins Spectrograph. For the first time, we combine two independent models used to quantify the outflow properties for down-the-barrel and transverse absorption. We find that the modeled down-the-barrel deprojected outflow velocities range between V {sub dtb} = 45-255 km s{sup –1}. The transverse bi-conical outflow model, assuming constant-velocity flows perpendicular to the disk, requires wind velocities V {sub outflow} = 40-80 km s{sup –1} to reproduce the transverse Mg II absorption kinematics, which is consistent with the range of V {sub dtb}. The galaxy has a metallicity, derived from Hα and N II, of [O/H] = –0.21 ± 0.08, whereas the transverse absorption has [X/H] = –1.12 ± 0.02. The galaxy star formation rate is constrained between 4.6-15 M {sub ☉} yr{sup –1} while the estimated outflow rate ranges between 1.6-4.2 M {sub ☉} yr{sup –1} and yields a wind loading factor ranging between 0.1-0.9. The galaxy and gas metallicities, the galaxy-quasar sight-line geometry, and the down-the-barrel and transverse modeled outflow velocities collectively suggest that the transverse gas originates from ongoing outflowing material from the galaxy. The ∼1 dex decrease in metallicity from the base of the outflow to the outer halo suggests metal dilution of the gas by the time it reached 58 kpc.

  13. Nonlinear Color–Metallicity Relations of Globular Clusters. VII. Nonlinear Absorption-line Index versus Metallicity Relations and Bimodal Index Distributions of NGC 5128 Globular Clusters

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sooyoung; Yoon, Suk-Jin, E-mail: sjyoon0691@yonsei.ac.kr [Department of Astronomy and Center for Galaxy Evolution Research, Yonsei University, Seoul 120-749 (Korea, Republic of)

    2017-07-01

    Spectroscopy on the globular cluster (GC) system of NGC 5128 revealed bimodality in absorption-line index distributions of its old GCs. GC division is a widely observed and studied phenomenon whose interpretation has depicted host galaxy formation and evolution such that it harbors two distinct metallicity groups. Such a conventional view of GC bimodality has mainly been based on photometry. The recent GC photometric data, however, presented an alternative perspective in which the nonlinear metallicity-to-color transformation is responsible for color bimodality of GC systems. Here we apply the same line of analysis to the spectral indices and examine the absorption-line index versus metallicity relations for the NGC 5128 GC system. NGC 5128 GCs display nonlinearity in the metallicity-index planes, most prominently for the Balmer lines and by a non-negligible degree for the metallicity-sensitive magnesium line. We demonstrate that the observed spectroscopic division of NGC 5128 GCs can be caused by the nonlinear nature of the metallicity-to-index conversions and thus one does not need to resort to two separate GC subgroups. Our analysis incorporating this nonlinearity provides a new perspective on the structure of NGC 5128's GC system, and a further piece to the global picture of the formation of GC systems and their host galaxies.

  14. INVISIBLE ACTIVE GALACTIC NUCLEI. II. RADIO MORPHOLOGIES AND FIVE NEW H i 21 cm ABSORPTION LINE DETECTORS

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Ting; Stocke, John T.; Darling, Jeremy [Center for Astrophysics and Space Astronomy, UCB 389, University of Colorado, Boulder, CO 80309-0389 (United States); Momjian, Emmanuel [National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801 (United States); Sharma, Soniya [Research School of Astronomy and Astrophysics, The Australian National University, Mt Stromlo Observatory, ACT 2611 (Australia); Kanekar, Nissim [National Centre for Radio Astrophysics, TIFR, Post Bag 3, Ganeshkhind, Pune 411 007 (India)

    2016-03-15

    This is the second paper directed toward finding new highly redshifted atomic and molecular absorption lines at radio frequencies. To this end, we selected a sample of 80 candidates for obscured radio-loud active galactic nuclei (AGNs) and presented their basic optical/near-infrared (NIR) properties in Paper I. In this paper, we present both high-resolution radio continuum images for all of these sources and H i 21 cm absorption spectroscopy for a few selected sources in this sample. A-configuration 4.9 and 8.5 GHz Very Large Array continuum observations find that 52 sources are compact or have substantial compact components with size <0.″5 and flux densities >0.1 Jy at 4.9 GHz. The 36 most compact sources were then observed with the Very Long Baseline Array at 1.4 GHz. One definite and 10 candidate Compact Symmetric Objects (CSOs) are newly identified, which is a detection rate of CSOs ∼three times higher than the detection rate previously found in purely flux-limited samples. Based on possessing compact components with high flux densities, 60 of these sources are good candidates for absorption-line searches. Twenty-seven sources were observed for H i 21 cm absorption at their photometric or spectroscopic redshifts with only six detections (five definite and one tentative). However, five of these were from a small subset of six CSOs with pure galaxy optical/NIR spectra (i.e., any AGN emission is obscured) and for which accurate spectroscopic redshifts place the redshifted 21 cm line in a radio frequency intereference (RFI)-free spectral “window” (i.e., the percentage of H i 21 cm absorption-line detections could be as high as ∼90% in this sample). It is likely that the presence of ubiquitous RFI and the absence of accurate spectroscopic redshifts preclude H i detections in similar sources (only 1 detection out of the remaining 22 sources observed, 13 of which have only photometric redshifts); that is, H i absorption may well be present but is masked by

  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. INFRARED ABSORPTION LINES TOWARD NGC 7538 IRS 1: ABUNDANCES OF H{sub 2}, H{sub 3}{sup +}, AND CO

    Energy Technology Data Exchange (ETDEWEB)

    Goto, Miwa [Universitäts-Sternwarte München, Scheinerstr. 1, D-81679 Munich (Germany); Geballe, T. R. [Gemini Observatory, 670 North A‘ohoku Place, Hilo, HI 96720 (United States); Usuda, Tomonori, E-mail: mgoto@usm.lmu.de, E-mail: tgeballe@gemini.edu, E-mail: usuda@naoj.org [Subaru Telescope, 650 North A‘ohoku Place, Hilo, HI 96720 (United States)

    2015-06-10

    We report high-resolution near-infrared absorption spectroscopy of H{sub 2}, H{sub 3}{sup +}, and CO toward the young high mass object NGC 7538 IRS 1. The v = 1–0 H{sub 2} S(0) line and lines in the CO v = 2–0 band were detected; the v = 1–0 H{sub 2} S(1) line and the v = 1–0 H{sub 3}{sup +} lines [R(1, 1){sup l}, R(1, 0), R(1, 1){sup u}] were not detected. The line of sight traverses two clouds, with temperatures 45 and 259 K and with roughly equal column densities of CO. Assuming that H{sub 2} is at the same temperature as CO and that the two species are uniformly mixed, [H{sub 2}]/[CO] = 3600 ± 1200. NGC 7538 is the most distant object from the Galactic center for which [H{sub 2}]/[CO] has been directly measured using infrared absorption spectroscopy.

  17. Broad absorption line symbiotic stars: highly ionized species in the fast outflow from MWC 560

    Science.gov (United States)

    Lucy, Adrian B.; Knigge, Christian; Sokoloski, J. L.

    2018-04-01

    In symbiotic binaries, jets and disk winds may be integral to the physics of accretion onto white dwarfs from cool giants. The persistent outflow from symbiotic star MWC 560 (≡V694 Mon) is known to manifest as broad absorption lines (BALs), most prominently at the Balmer transitions. We report the detection of high-ionization BALs from C IV, Si IV, N V, and He II in International Ultraviolet Explorer spectra obtained on 1990 April 29 - 30, when an optical outburst temporarily erased the obscuring `iron curtain' of absorption troughs from Fe II and similar ions. The C IV and Si IV BALs reached maximum radial velocities at least 1000 km s-1 higher than contemporaneous Mg II and He II BALs; the same behaviors occur in the winds of quasars and cataclysmic variables. An iron curtain lifts to unveil high-ionization BALs during the P Cygni phase observed in some novae, suggesting by analogy a temporary switch in MWC 560 from persistent outflow to discrete mass ejection. At least three more symbiotic stars exhibit broad absorption with blue edges faster than 1500 km s-1; high-ionization BALs have been reported in AS 304 (≡V4018 Sgr), while transient Balmer BALs have been reported in Z And and CH Cyg. These BAL-producing fast outflows can have wider opening angles than has been previously supposed. BAL symbiotics are short-timescale laboratories for their giga-scale analogs, broad absorption line quasars (BALQSOs), which display a similarly wide range of ionization states in their winds.

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

    Science.gov (United States)

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

    1990-01-01

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

  19. 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...

  20. 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.

  1. Retrieval of canopy water content of different crop types with two new hyperspectral indices: Water Absorption Area Index and Depth Water Index

    Science.gov (United States)

    Pasqualotto, Nieves; Delegido, Jesús; Van Wittenberghe, Shari; Verrelst, Jochem; Rivera, Juan Pablo; Moreno, José

    2018-05-01

    Crop canopy water content (CWC) is an essential indicator of the crop's physiological state. While a diverse range of vegetation indices have earlier been developed for the remote estimation of CWC, most of them are defined for specific crop types and areas, making them less universally applicable. We propose two new water content indices applicable to a wide variety of crop types, allowing to derive CWC maps at a large spatial scale. These indices were developed based on PROSAIL simulations and then optimized with an experimental dataset (SPARC03; Barrax, Spain). This dataset consists of water content and other biophysical variables for five common crop types (lucerne, corn, potato, sugar beet and onion) and corresponding top-of-canopy (TOC) reflectance spectra acquired by the hyperspectral HyMap airborne sensor. First, commonly used water content index formulations were analysed and validated for the variety of crops, overall resulting in a R2 lower than 0.6. In an attempt to move towards more generically applicable indices, the two new CWC indices exploit the principal water absorption features in the near-infrared by using multiple bands sensitive to water content. We propose the Water Absorption Area Index (WAAI) as the difference between the area under the null water content of TOC reflectance (reference line) simulated with PROSAIL and the area under measured TOC reflectance between 911 and 1271 nm. We also propose the Depth Water Index (DWI), a simplified four-band index based on the spectral depths produced by the water absorption at 970 and 1200 nm and two reference bands. Both the WAAI and DWI outperform established indices in predicting CWC when applied to heterogeneous croplands, with a R2 of 0.8 and 0.7, respectively, using an exponential fit. However, these indices did not perform well for species with a low fractional vegetation cover (<30%). HyMap CWC maps calculated with both indices are shown for the Barrax region. The results confirmed the

  2. Low redshift Lyman alpha absorption lines and the dark matter halos of disk galaxies

    Science.gov (United States)

    Maloney, Philip

    1993-01-01

    Recent observations using the Hubble Space Telescope of the z = 0.156 QSO 3C 273 have discovered a surprisingly large number of Ly-alpha absorption lines. In particular, Morris et al. found 9 certain and 7 possible Ly-alpha lines with equivalent widths above 25 mA. This is much larger (by a factor of 5-10) than the number expected from extrapolation of the high-redshift behavior of the Ly-alpha forest. Within the context of pressure-confined models for the Ly-alpha clouds, this behavior can be understood if the ionizing background declines sharply between z is approximately 2 and z is approximately 0. However, this requires that the ionizing photon flux drop as rapidly as the QSO volume emissivity; moreover, the absorbers must have a space density n(sub O) is approximately 2.6(N/10)h/((D/100 kpc)(sup 2)) Mpc(sup -3) where D is the present-day diameter of the absorbers. It is somewhat surprising that such necessarily fragile objects could have survived in such numbers to the present day. It is shown that it is plausible that the atomic hydrogen extents of spiral and irregular galaxies are large enough to produce the observed number of Ly-alpha absorption lines toward 3C 273, and that the neutral column densities and doppler b-values expected under these conditions fall in the range found by Morris et al. (1991).

  3. 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.

  4. 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).

  5. 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.

  6. 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

  7. NuSTAR reveals an intrinsically x-ray weak broad absorption line quasar in the ultraluminous infrared galaxy Markarian 231

    DEFF Research Database (Denmark)

    Teng, Stacy H.; Brandt, W. N.; Harrison, F. A.

    2014-01-01

    -ionization broad absorption line quasar that is intrinsically X-ray weak. The weak ionizing continuum may explain the lack of mid-infrared [O IV], [Ne V], and [Ne VI] fine-structure emission lines which are present in sources with otherwise similar AGN properties. We argue that the intrinsic X-ray weakness may...

  8. Higher‐order mode absorption measurement of X-band choke-mode cavities in a radial line structure

    International Nuclear Information System (INIS)

    Zha, Hao; Shi, Jiaru; Wu, Xiaowei; Chen, Huaibi

    2016-01-01

    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.

  9. 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.

  10. Real-time trace gas sensor using a multimode diode laser and multiple-line integrated cavity enhanced absorption spectroscopy.

    Science.gov (United States)

    Karpf, Andreas; Rao, Gottipaty N

    2015-07-01

    We describe and demonstrate a highly sensitive trace gas sensor based on a simplified design that is capable of measuring sub-ppb concentrations of NO2 in tens of milliseconds. The sensor makes use of a relatively inexpensive Fabry-Perot diode laser to conduct off-axis cavity enhanced spectroscopy. The broad frequency range of a multimode Fabry-Perot diode laser spans a large number of absorption lines, thereby removing the need for a single-frequency tunable laser source. The use of cavity enhanced absorption spectroscopy enhances the sensitivity of the sensor by providing a pathlength on the order of 1 km in a small volume. Off-axis alignment excites a large number of cavity modes simultaneously, thereby reducing the sensor's susceptibility to vibration. Multiple-line integrated absorption spectroscopy (where one integrates the absorption spectra over a large number of rovibronic transitions of the molecular species) further improves the sensitivity of detection. Relatively high laser power (∼400  mW) is used to compensate for the low coupling efficiency of a broad linewidth laser to the optical cavity. The approach was demonstrated using a 407 nm diode laser to detect trace quantities of NO2 in zero air. Sensitivities of 750 ppt, 110 ppt, and 65 ppt were achieved using integration times of 50 ms, 5 s, and 20 s respectively.

  11. The methane absorption spectrum near 1.73 μm (5695-5850 cm-1): Empirical line lists at 80 K and 296 K and rovibrational assignments

    Science.gov (United States)

    Ghysels, M.; Mondelain, D.; Kassi, S.; Nikitin, A. V.; Rey, M.; Campargue, A.

    2018-07-01

    The methane absorption spectrum is studied at 297 K and 80 K in the center of the Tetradecad between 5695 and 5850 cm-1. The spectra are recorded by differential absorption spectroscopy (DAS) with a noise equivalent absorption of about αmin≈ 1.5 × 10-7 cm-1. Two empirical line lists are constructed including about 4000 and 2300 lines at 297 K and 80 K, respectively. Lines due to 13CH4 present in natural abundance were identified by comparison with a spectrum of pure 13CH4 recorded in the same temperature conditions. About 1700 empirical values of the lower state energy level, Eemp, were derived from the ratios of the line intensities at 80 K and 296 K. They provide accurate temperature dependence for most of the absorption in the region (93% and 82% at 80 K and 296 K, respectively). The quality of the derived empirical values is illustrated by the clear propensity of the corresponding lower state rotational quantum number, Jemp, to be close to integer values. Using an effective Hamiltonian model derived from a previously published ab initio potential energy surface, about 2060 lines are rovibrationnally assigned, adding about 1660 new assignments to those provided in the HITRAN database for 12CH4 in the region.

  12. 51Cr-ethylenediaminetetraacetic acid absorption test

    International Nuclear Information System (INIS)

    Aabakken, L.

    1989-01-01

    The 51 Cr-ethylenediaminetetraacetic acid (EDTA) absorption test was evaluated in 83 healthy, male volunteers. Base-line 24 h excretion after peroral administration ranged from 0.88% to 7.96%, with a higher median absorption than reported by most authors (2.45%). However, the reproducibility and stability of the method and the reproducibility of the results were satisfactory. Urinary excretion after intraduodenal installation (n=18) was comparable to that seen after peroral test dose administration, indicating a limited significance of gastric 51 Cr-EDTA absorption under normal conditions. In 16 subjects a single intake of alcohol immediately before the test gave a modest and short-lasting increase in 51 Cr-EDTA absorption. No correlation was seen to body mass index, creatinine clearance, urinary volume, or small-bowel transit time, possibly reducing the number of confounding factors in the evaluation of absorption data. A small but significant negative correlation was, however, found to body surface area and age

  13. Randic and Schultz molecular topological indices and their correlation with some X-ray absorption parameters

    International Nuclear Information System (INIS)

    Khatri, Sunil; Kekre, Pravin A; Mishra, Ashutosh

    2016-01-01

    The properties of a molecular system are affected by the topology of molecule. Therefore many studies have been made where the various physic-chemical properties are correlated with the topological indices. These studies have shown a very good correlation demonstrating the utility of the graph theoretical approach. It is, therefore, very natural to expect that the various physical properties obtained by the X-ray absorption spectra may also show correlation with the topological indices. Some complexes were used to establish correlation between topological indices and some X-ray absorption parameters like chemical shift. The chemical shift is on the higher energy side of the metal edge in these complexes. The result obtained in these studies shows that the topological indices of organic molecule acting as a legands can be used for estimating edge shift theoretically. (paper)

  14. 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.

  15. THE PITTSBURGH SLOAN DIGITAL SKY SURVEY Mg II QUASAR ABSORPTION-LINE SURVEY CATALOG

    International Nuclear Information System (INIS)

    Quider, Anna M.; Nestor, Daniel B.; Turnshek, David A.; Rao, Sandhya M.; Weyant, Anja N.; Monier, Eric M.; Busche, Joseph R.

    2011-01-01

    We present a catalog of intervening Mg II quasar absorption-line systems in the redshift interval 0.36 ≤ z ≤ 2.28. The catalog was built from Sloan Digital Sky Survey Data Release Four (SDSS DR4) quasar spectra. Currently, the catalog contains ∼17, 000 measured Mg II doublets. We also present data on the ∼44, 600 quasar spectra which were searched to construct the catalog, including redshift and magnitude information, continuum-normalized spectra, and corresponding arrays of redshift-dependent minimum rest equivalent widths detectable at our confidence threshold. The catalog is available online. A careful second search of 500 random spectra indicated that, for every 100 spectra searched, approximately one significant Mg II system was accidentally rejected. Current plans to expand the catalog beyond DR4 quasars are discussed. Many Mg II absorbers are known to be associated with galaxies. Therefore, the combination of large size and well understood statistics makes this catalog ideal for precision studies of the low-ionization and neutral gas regions associated with galaxies at low to moderate redshift. An analysis of the statistics of Mg II absorbers using this catalog will be presented in a subsequent paper.

  16. White lines at the Lsub(I), Lsub(II), and Lsub(III) absorption edges of some rare earth compounds

    Energy Technology Data Exchange (ETDEWEB)

    Garg, K B; Sharma, B K; Jain, D C [Rajasthan Univ., Jaipur (India). Dept. of Physics; Sinha, A I.P. [Banasthali Vidyapeeth (India). Dept. of Chemistry

    1980-11-01

    The paper reports the appearance of white lines (WLS) at all the three L-absorption edges of the sulfur coordinated thiosalicylic acid compounds of Sm, Tb, and Dy. The profiles of the observed WLS are presented and discussed.

  17. Evaluation of Optical Depths and Self-Absorption of Strontium and Aluminum Emission Lines in Laser-Induced Breakdown Spectroscopy (LIBS).

    Science.gov (United States)

    Alfarraj, Bader A; Bhatt, Chet R; Yueh, Fang Yu; Singh, Jagdish P

    2017-04-01

    Laser-induced breakdown spectroscopy (LIBS) is a widely used laser spectroscopic technique in various fields, such as material science, forensic science, biological science, and the chemical and pharmaceutical industries. In most LIBS work, the analysis is performed using radiative transitions from atomic emissions. In this study, the plasma temperature and the product [Formula: see text] (the number density N and the absorption path length [Formula: see text]) were determined to evaluate the optical depths and the self-absorption of Sr and Al lines. A binary mixture of strontium nitrate and aluminum oxide was used as a sample, consisting of variety of different concentrations in powder form. Laser-induced breakdown spectroscopy spectra were collected by varying various parameters, such as laser energy, gate delay time, and gate width time to optimize the LIBS signals. Atomic emission from Sr and Al lines, as observed in the LIBS spectra of different sample compositions, was used to characterize the laser induced plasma and evaluate the optical depths and self-absorption of LIBS.

  18. Test and evaluation of the in-line plutonium solution K-absorption-edge densitometer at the Savannah River Plant. Phase I. Off-line testing results

    International Nuclear Information System (INIS)

    Smith, H.A. Jr.; Marks, T.; Johnson, S.S.

    1982-04-01

    An in-line, plutonium-solution, K-edge absorption densitometer has been developed at Los Alamos and is currently undergoing test and evaluation at the Savannah River Plant (SRP). The first phase of the test and evaluation (off-line instrument calibration and solution assays) was completed, and preparations are under way to install the instrument in-line, as soon as process schedules permit. Calibration data in the design concentration range of 25 to 40 g Pu/L demonstrate routine achievement of densitometry assay precisions of 0.5% or better in 40 min. Plutonium assays at concentrations outside the calibration range were investigated in an effort to define better the limitations of the instrument and address other possible assay situations at SRP. Densitometry precisions obtained for 40-min assays range from 3% to 5 g Pu/L down to 0.4% at 70 g Pu/L. At higher plutonium concentrations, the precision deteriorated due to increasing gamma-ray absorption by the solution. In addition, with actinide concentrations above approximately 100 g/L, the assay accuracy also suffered because of enhanced small-angle scattering effects in the large sample cell. Measurements on mixed U/Pu solutions demonstrated the feasibility of accurate plutonium assays with correction for the large uranium matrix contributions being determined from the measurement data. The 239 240 Pu weight fractions and 241 Pu/ 239 Pu and 238 Pu/ 239 Pu isotopic ratios can be determined. In a mockup of the in-line solution plumbing system, all assay sequences, error conditions, and interlock criteria were exercised and verified to be working properly

  19. Prediction of temperature-insensitive molecular absorption lines in laser-assisted combustion diagnostics

    International Nuclear Information System (INIS)

    Walewski, Joachim W.; Elmqvist, Anders

    2005-01-01

    In laser-assisted combustion diagnostics it is a recurring task to predict molecular transitions whose signal strength depends only weakly on variations in temperature. The signal strength is proportional to the Boltzmann fraction of the level probed and the amplitude of the absorption line profile. In the past investigations have been presented in which this task was attack by detailed numerical calculations of the temperature dependence of pertinent physical properties of the molecule. Another widely applied approach relies on an analytical formula for the Boltzmann fraction of hetero-nuclear diatomic molecules and the neglect of line shape effects. The analytical approach experiences a continuing popularity in laser-assisted combustion diagnostics, which is why we compared both approaches with each other. The objective of this comparison was to assess the accuracy of the analytical approach and to reveal its potential pitfalls. Our comparison revealed that the analytical approach suffers from mediocre accuracy, which makes it unfit for practical applications. One cause is the neglect of higher lying vibrational levels, which show a non-negligible population for typical flame temperatures. Another reason is the neglect of fine structure splitting in molecules with non-zero orbit angular momentum in the ground state. Another reason for the observed inaccuracy is the neglect of line shape effects quenching, which were found to have a significant effect on the temperature sensitivity of a line. Because of its insufficient accuracy due to both oversimplified models of the molecular energy levels and the neglect of line shape effects and quenching we discourage from applying the analytical approach and recommend the use of detailed numerical approaches that are free of the above limitations

  20. 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

  1. THE INTRINSIC FRACTIONS AND RADIO PROPERTIES OF LOW-IONIZATION BROAD ABSORPTION LINE QUASARS

    International Nuclear Information System (INIS)

    Dai Xinyu; Shankar, Francesco; Sivakoff, Gregory R.

    2012-01-01

    Low-ionization (Mg II, Fe II, and Fe III) broad absorption line quasars (LoBALs) probe a relatively obscured quasar population and could be at an early evolutionary stage for quasars. We study the intrinsic fractions of LoBALs using the Sloan Digital Sky Survey (SDSS), Two Micron All Sky Survey, and Faint Images of the Radio Sky at Twenty cm survey. We find that the LoBAL fractions of the near-infrared (NIR) and radio samples are approximately 5-7 times higher than those measured in the optical sample. This suggests that the fractions measured in the NIR and radio bands are closer to the intrinsic fractions of the populations, and that the optical fractions are significantly biased due to obscuration effects, similar to high-ionization broad absorption line quasars (HiBALs). Considering a population of obscured quasars that do not enter the SDSS, which could have a much higher LoBAL fraction, we expect that the intrinsic fraction of LoBALs could be even higher. We also find that the LoBAL fractions decrease with increasing radio luminosities, again, similarly to HiBALs. In addition, we find evidence for increasing fractions of LoBALs toward higher NIR luminosities, especially for FeLoBALs with a fraction of ∼18% at M K s < -31 mag. This population of NIR-luminous LoBALs may be at an early evolutionary stage of quasar evolution. To interpret the data, we use a luminosity-dependent model for LoBALs that yields significantly better fits than those from a pure geometric model.

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

    OpenAIRE

    Lotter, Andreas

    2006-01-01

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

  3. Observations of nickel, chromium, and zinc in QSO absorption-line systems

    International Nuclear Information System (INIS)

    Meyer, D.M.; Roth, K.C.

    1990-01-01

    New observations of Ni II, Cr II, and Zn II in several damped Ly-alpha QSO absorption-line systems at z about 2 are presented. Using the N(Zn II)/N(H I) ratio as a probe of the metallicity and N(Cr II)/N(Zn II) as a measure of the dust content, it is found that the heavy-element abundances in the z = 1.921 system toward the QSO 2206-199N are 20 percent solar and that the dust-to-gas ratio is 11 percent of the Galactic disk value. The observations of these species in the z = 2.309 system toward PHL 957 yield a more extreme metallicity (4 percent solar) and dust-to-gas ratio (3 percent Galactic). In addition, a depletion of Ni in the z = 2.039 absorber toward PKS 0458 - 020 and an absence of C I absorption in the z about 2 damped systems toward 1215 + 333 and 2359 - 022 are found which are consistent with a lack of dust. Among the four damped systems whose Ni, Cr, and Zn abundances have been examined quantitatively to date, all show convincing evidence of much lower metallicities and dust content than the Galactic disk. The implications of these results with regard to the interpretation of the high-redshift damped Ly-alpha systems as an evolving population of young galaxies are discussed. 41 refs

  4. 21 CFR 872.1850 - Lead-lined position indicator.

    Science.gov (United States)

    2010-04-01

    ... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Diagnostic Devices § 872.1850 Lead-lined position indicator. (a... dental x-ray tube and intended to aid in positioning the tube, to prevent the misfocusing of the x-rays by absorbing divergent radiation, and to prevent leakage of radiation. (b) Classification. Class I...

  5. Constraints on gamma-ray burst and supernova progenitors through circumstellar absorption lines : II. Post-LBV Wolf-Rayet stars

    NARCIS (Netherlands)

    Marle, A.J.; Langer, N.; Garcia-Segura, G.

    2007-01-01

    Van Marle et al. (2005) showed that circumstellar absorption lines in early Type Ib/c supernova and gamma-ray burst afterglow spectra may reveal the progenitor evolution of the exploding Wolf-Rayet star. While the quoted paper deals with Wolf-Rayet stars which evolved through a red supergiant stage,

  6. Galactic absorption line coronae

    International Nuclear Information System (INIS)

    Bregman, J.N.

    1981-01-01

    We have investigated whether gaseous coronae around galaxies rise to the absorption systems seen in quasar spectra. In our model, gas originally located in the disk is heated to the million degree range and rises to surround the galaxy; the gas remains bound to the galaxy. Optically thin radiative cooling drives a thermal instability in the hot gas which causes cool clouds (T 4 K) to condense out of the corona. These clouds, which follow ballistic trajectories back to the disk, are the absorption sites. A two-dimensional hydrodynamic code with radiative cooling was used to study the dynamics and thermodynamics of the corona as well as the position rate at which clouds form. Coupled to the code is a galaxy with two mass components, a disk (approx.10 11 M/sub sun/) and a dark halo (approx.10 12 M/sub sun/). In a model where the temperature at the base of the corona (in the disk) is 3 x 10 6 K, absorbing gas of column density NL> or approx. =10 18 cm 2 extends radially to 100 kpc (face-on orientation) and vertically to 60 Kpc (edge-on orientation). The total mass of gas required here (coronal plus cloud gas) is 1.4 x 10 10 M/sub sun/, while the minimum supernova heating rate is one supernova per 27 years. In two other models (base coronal temperatures of 0.50 x 10 6 K and 1 x 10 6 K), coronal gas rises from an extended gaseous disk (in the previous model, the gas comes from a typical gaseous disk approximately 15 kpc in extent). Here, column densities of 10 19 cm -2 out to a radius of 70 kpc (face-on orientation) are achieved with a total gas mass of 1.7 x 10 9 M/sub direct-product/ and 2.0 x 10 9 M/sub sun/ and minimum heating rates of approximately one supernova per 170 years and one supernova per 60 years

  7. BROAD ABSORPTION LINE VARIABILITY 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. [Astronomy Department, University of Washington, Seattle, WA 98195 (United States); Hamann, F. [Department of Astronomy, University of Florida, Gainesville, FL 32611-2055 (United States); Lundgren, B. F. [Department of Astronomy, University of Wisconsin, Madison, WI 53706 (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. [Universite Paris 6, Institut d' Astrophysique de Paris, 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 St., MS-51, Cambridge, MA 02138 (United States); York, Don, E-mail: nfilizak@astro.psu.edu [The University of Chicago, Department of Astronomy and Astrophysics, Chicago, IL 60637 (United States)

    2013-11-10

    We present a detailed investigation of the variability of 428 C IV and 235 Si IV broad absorption line (BAL) troughs identified in multi-epoch observations of 291 quasars by the Sloan Digital Sky Survey-I/II/III. These observations primarily sample rest-frame timescales of 1-3.7 yr over which significant rearrangement of the BAL wind is expected. We derive a number of observational results on, e.g., the frequency of BAL variability, the velocity range over which BAL variability occurs, the primary observed form of BAL-trough variability, the dependence of BAL variability upon timescale, the frequency of BAL strengthening versus weakening, correlations between BAL variability and BAL-trough profiles, relations between C IV and Si IV BAL variability, coordinated multi-trough variability, and BAL variations as a function of quasar properties. We assess implications of these observational results for quasar winds. Our results support models where most BAL absorption is formed within an order-of-magnitude of the wind-launching radius, although a significant minority of BAL troughs may arise on larger scales. We estimate an average lifetime for a BAL trough along our line-of-sight of a few thousand years. BAL disappearance and emergence events appear to be extremes of general BAL variability, rather than being qualitatively distinct phenomena. We derive the parameters of a random-walk model for BAL EW variability, finding that this model can acceptably describe some key aspects of EW variability. The coordinated trough variability of BAL quasars with multiple troughs suggests that changes in 'shielding gas' may play a significant role in driving general BAL variability.

  8. Laser-based absorption spectroscopy as a technique for rapid in-line analysis of respired gas concentrations of O2 and CO2.

    Science.gov (United States)

    Cummings, Beth; Hamilton, Michelle L; Ciaffoni, Luca; Pragnell, Timothy R; Peverall, Rob; Ritchie, Grant A D; Hancock, Gus; Robbins, Peter A

    2011-07-01

    The use of sidestream analyzers for respired gas analysis is almost universal. However, they are not ideal for measurements of respiratory gas exchange because the analyses are both temporally dissociated from measurements of respiratory flow and also not generally conducted under the same physical conditions. This study explores the possibility of constructing an all optical, fast response, in-line breath analyzer for oxygen and carbon dioxide. Using direct absorption spectroscopy with a diode laser operating at a wavelength near 2 μm, measurements of expired carbon dioxide concentrations were obtained with an absolute limit of detection of 0.04% at a time resolution of 10 ms. Simultaneously, cavity enhanced absorption spectroscopy at a wavelength near 760 nm was employed to obtain measurements of expired oxygen concentrations with an absolute limit of detection of 0.26% at a time resolution of 10 ms. We conclude that laser-based absorption spectroscopy is a promising technology for in-line analysis of respired carbon dioxide and oxygen concentrations.

  9. CH+(1-0) and 13CH+(1-0) absorption lines in the direction of massive star-forming regions

    NARCIS (Netherlands)

    Falgarone, E.; Godard, B.; Cernicharo, J.; de Luca, M.; Gerin, M.; Phillips, T. G.; Black, J. H.; Lis, D. C.; Bell, T. A.; Boulanger, F.; Coutens, A.; Dartois, E.; Encrenaz, P.; Giesen, T.; Goicoechea, J. R.; Goldsmith, P. F.; Gupta, H.; Gry, C.; Hennebelle, P.; Herbst, E.; Hily-Blant, P.; Joblin, C.; Kaźmierczak, M.; Kołos, R.; Krełowski, J.; Martin-Pintado, J.; Monje, R.; Mookerjea, B.; Neufeld, D. A.; Perault, M.; Pearson, J. C.; Persson, C.; Plume, R.; Salez, M.; Schmidt, M.; Sonnentrucker, P.; Stutzki, J.; Teyssier, D.; Vastel, C.; Yu, S.; Menten, K.; Geballe, T. R.; Schlemmer, S.; Shipman, R.; Tielens, A. G. G. M.; Philipp, S.; Cros, A.; Zmuidzinas, J.; Samoska, L. A.; Klein, K.; Lorenzani, A.; Szczerba, R.; Péron, I.; Cais, P.; Gaufre, P.; Ravera, L.; Morris, P.; Lord, S.; Planesas, P.

    2010-01-01

    We report the detection of the ground-state rotational transition of the methylidyne cation CH+ and its isotopologue 13CH+ toward the remote massive star-forming regions W33A, W49N, and W51 with the HIFI instrument onboard the Herschel satellite. Both lines are seen only in absorption against the

  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. Photo absorption studies of polyatomic molecules using Indus 1 synchrotron radiation source

    International Nuclear Information System (INIS)

    Saraswathy, P.; Sunanda, K.; Aparna, S.; Rajashekar, B.N.; Das, N.C.

    2004-06-01

    The Photophysics beamline is a medium resolution beamline designed for carrying out photo absorption and fluorescence experiments using the synchrotron radiation source Indus-l. This beamline has been commissioned recently and is in operation. An experimental setup for gas phase absorption studies has been developed and installed. Absorption spectra of a few polyatomicmolecules viz. benzene, ammonia, carbon disulphide and acetone were recorded in the wavelength region 1500 -3000 A. The results from this study indicated the satisfactory performance of the beam line as well as the experimental setup. Details of the first set of absorption experiments carried out are discussed in this report. (author)

  12. The Redshifted Hydrogen Balmer and Metastable He 1 Absorption Line System in Mini-FeLoBAL Quasar SDSS J112526.12+002901.3: A Parsec-scale Accretion Inflow?

    Science.gov (United States)

    Shi, Xi-Heng; Jiang, Peng; Wang, Hui-Yuan; Zhang, Shao-Hua; Ji, Tuo; Liu, Wen-Juan; Zhou, Hong-Yan

    2016-10-01

    The accretion of the interstellar medium onto central super-massive black holes is widely accepted as the source of the gigantic energy released by the active galactic nuclei. However, few pieces of observational evidence have been confirmed directly demonstrating the existence of the inflows. The absorption line system in the spectra of quasar SDSS J112526.12+002901.3 presents an interesting example in which the rarely detected hydrogen Balmer and metastable He I absorption lines are found redshifted to the quasar's rest frame along with the low-ionization metal absorption lines Mg II, Fe II, etc. The repeated SDSS spectroscopic observations suggest a transverse velocity smaller than the radial velocity. The motion of the absorbing medium is thus dominated by infall. The He I* lines present a powerful probe to the strength of ionizing flux, while the Balmer lines imply a dense environment. With the help of photoionization simulations, we find that the absorbing medium is exposed to the radiation with ionization parameter U ≈ 10-1.8, and the density is n({{H}})≈ {10}9 {{cm}}-3. Thus the absorbing medium is located ˜4 pc away from the central engine. According to the similarity in the distance and physical conditions between the absorbing medium and the torus, we strongly propose the absorption line system as a candidate for the accretion inflow, which originates in the inner surface of the torus.

  13. 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.

  14. The CO_2 absorption spectrum in the 2.3 µm transparency window by high sensitivity CRDS: (I) Rovibrational lines

    International Nuclear Information System (INIS)

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

    2016-01-01

    The absorption of carbon dioxide is very weak near 2.3 µm which makes this transparency window of particular interest for the study of Venus’ lower atmosphere. As a consequence of the weakness of the transitions located in this region, previous experimental data are very scarce and spectroscopic databases provide calculated line lists which should be tested and validated by experiment. In this work, we use the Cavity Ring Down Spectroscopy (CRDS) technique for a high sensitivity characterization of the CO_2 absorption spectrum in two spectral intervals of the 2.3 µm window: 4248–4257 and 4295–4380 cm"−"1 which were accessed using a Distributed Feed Back (DFB) diode laser and a Vertical External Cavity Surface Emitting Laser (VECSEL) as light sources, respectively. The achieved sensitivity (noise equivalent absorption, α_m_i_n, on the order of 5×10"−"1"0 cm"−"1) allowed detecting numerous new transitions with intensity values down to 5×10"−"3"0 cm/molecule. The rovibrational assignments were performed by comparison with available theoretical line lists in particular those obtained at IAO Tomsk using the global effective operator approach. Hot bands of the main isotopologue and "1"6O"1"2C"1"8O bands were found to be missing in the HITRAN database while they contribute importantly to the absorption in the region. Additional CRDS spectra of a CO_2 sample highly enriched in "1"8O were recorded in order to improve the spectroscopy of this isotopologue. As a result about 700 lines of "1"6O"1"2C"1"8O, "1"6O"1"2C"1"7O, "1"7O"1"2C"1"8O, "1"2C"1"8O_2 and "1"3C"1"8O_2 were newly measured. The status of the different databases (HITRAN, CDSD, variational calculations) in the important 2.3 µm transparency window is discussed. Possible improvements to correct evidenced deficiencies are suggested. - Highlights: • High sensitivity CRDS with a VECSEL in the 2.3 µm transparency window of CO_2. • Natural and "1"8O enriched CO_2 spectra recorded with

  15. Recent advances in on-line coupling of capillary electrophoresis to atomic absorption and fluorescence spectrometry for speciation analysis and studies of metal-biomolecule interactions

    International Nuclear Information System (INIS)

    Li Yan; Yin Xuebo; Yan Xiuping

    2008-01-01

    Speciation information is vital for the understanding of the toxicity, mobility and bioavailability of elements in environmental or biological samples. Hyphenating high resolving power of separation techniques and element-selective detectors provides powerful tools for studying speciation of trace elements in environmental and biological systems. During the last five years several novel hybrid techniques based on capillary electrophoresis (CE) and atomic spectrometry have been developed for speciation analysis and metal-biomolecule interaction study in our laboratory. These techniques include CE on-line coupled with atomic fluorescence spectrometry (AFS), chip-CE on-line coupled with AFS, CE on-line coupled with flame heated quartz furnace atomic absorption spectrometry (FHF-AAS), and CE on-line coupled with electrothermal atomic absorption spectrometry (ETAAS). The necessity for the development of these techniques, their interface design, and applications in speciation analysis and metal-biomolecule interaction study are reviewed. The advantages and limitations of the developed hybrid techniques are critically discussed, and further development is also prospected

  16. Experimental Line List of Water Vapor Absorption Lines in the Spectral Ranges 1850 - 2280 CM-1 and 2390-4000 CM-1

    Science.gov (United States)

    Loos, Joep; Birk, Manfred; Wagner, Georg

    2017-06-01

    A new experimental line parameter list of water vapor absorption lines in the spectral ranges 1850 - 2280 cm-1 and 2390 - 4000 cm-1 is presented. The line list is based on the analysis of several transmittance spectra measured using a Bruker IFS 125 HR high resolution Fourier transform spectrometer. A total of 54 measurements of pure water and water/air-mixtures at 296 K as well as water/air-mixtures at high and low temperatures were performed. A multispectrum fitting approach was used applying a quadratic speed-dependent hard collision line shape model in the Hartmann-Tran implementation extended to account for line mixing in the Rosenkranz approximation in order to retrieve line positions, intensities, self- and air-broadening parameters, their speed-dependence, self- and air-shifts as well as line mixing and in some cases collisional narrowing parameters. Additionally, temperature dependence parameters for widths, shifts and in a few cases line mixing were retrieved. For every parameter an extensive error estimation calculation was performed identifying and specifying systematic error sources. The resulting parameters are compared to the databases HITRAN12 as well as experimental values. For intensities, a detailed comparison to results of recent ab initio calculations performed at University College London was done showing an agreement within 2 % for a majority of the data. However, for some bands there are systematic deviations attributed to ab initio calculation errors. .H. Ngo et al. JQSRT 129, 89-100 (2013) doi:10.1016/j.jqsrt.2013.05.034; JQSRT 134, 105 (2014) doi:10.1016/j.jqsrt.2013.10.016. H. Tran et al. JQSRT 129, 199-203 (2013) doi:10.1016/j.jqsrt.2013.06.015; JQSRT 134, 104 (2014) doi:10.1016/j.jqsrt.2013.10.015. L.S. Rothman et al. JQSRT 130, 4-50 (2013) doi:10.1016/j.jqsrt.2013.07.002. N. Jacquinet-Husson et al. JMS 112, 2395-2445 (2016) doi:10.1016/j.jms.2016.06.007.

  17. GAMMA–GAMMA ABSORPTION IN THE BROAD LINE REGION RADIATION FIELDS OF GAMMA-RAY BLAZARS

    Energy Technology Data Exchange (ETDEWEB)

    Böttcher, Markus; Els, Paul, E-mail: Markus.Bottcher@nwu.ac.za [Centre for Space Research, North-West University, Potchefstroom, 2531 (South Africa)

    2016-04-20

    The expected level of γγ absorption in the Broad Line Region (BLR) radiation field of γ -ray loud Flat Spectrum Radio Quasars (FSRQs) is evaluated as a function of the location of the γ -ray emission region. This is done self-consistently with parameters inferred from the shape of the spectral energy distribution (SED) in a single-zone leptonic EC-BLR model scenario. We take into account all geometrical effects both in the calculation of the γγ opacity and the normalization of the BLR radiation energy density. As specific examples, we study the FSRQs 3C279 and PKS 1510-089, keeping the BLR radiation energy density at the location of the emission region fixed at the values inferred from the SED. We confirm previous findings that the optical depth due to γγ absorption in the BLR radiation field exceeds unity for both 3C279 and PKS 1510-089 for locations of the γ -ray emission region inside the inner boundary of the BLR. It decreases monotonically, with distance from the central engine and drops below unity for locations within the BLR. For locations outside the BLR, the BLR radiation energy density required for the production of GeV γ -rays rapidly increases beyond observational constraints, thus making the EC-BLR mechanism implausible. Therefore, in order to avoid significant γγ absorption by the BLR radiation field, the γ -ray emission region must therefore be located near the outer boundary of the BLR.

  18. An accelerated line-by-line option for MODTRAN combining on-the-fly generation of line center absorption within 0.1 cm-1 bins and pre-computed line tails

    Science.gov (United States)

    Berk, Alexander; Conforti, Patrick; Hawes, Fred

    2015-05-01

    A Line-By-Line (LBL) option is being developed for MODTRAN6. The motivation for this development is two-fold. Firstly, when MODTRAN is validated against an independent LBL model, it is difficult to isolate the source of discrepancies. One must verify consistency between pressure, temperature and density profiles, between column density calculations, between continuum and particulate data, between spectral convolution methods, and more. Introducing a LBL option directly within MODTRAN will insure common elements for all calculations other than those used to compute molecular transmittances. The second motivation for the LBL upgrade is that it will enable users to compute high spectral resolution transmittances and radiances for the full range of current MODTRAN applications. In particular, introducing the LBL feature into MODTRAN will enable first-principle calculations of scattered radiances, an option that is often not readily available with LBL models. MODTRAN will compute LBL transmittances within one 0.1 cm-1 spectral bin at a time, marching through the full requested band pass. The LBL algorithm will use the highly accurate, pressure- and temperature-dependent MODTRAN Padé approximant fits of the contribution from line tails to define the absorption from all molecular transitions centered more than 0.05 cm-1 from each 0.1 cm-1 spectral bin. The beauty of this approach is that the on-the-fly computations for each 0.1 cm-1 bin will only require explicit LBL summing of transitions centered within a 0.2 cm-1 spectral region. That is, the contribution from the more distant lines will be pre-computed via the Padé approximants. The status of the LBL effort will be presented. This will include initial thermal and solar radiance calculations, validation calculations, and self-validations of the MODTRAN band model against its own LBL calculations.

  19. Determination of cobalt in biological samples by line-source and high-resolution continuum source graphite furnace atomic absorption spectrometry using solid sampling or alkaline treatment

    International Nuclear Information System (INIS)

    Ribeiro, Anderson Schwingel; Vieira, Mariana Antunes; Furtado da Silva, Alessandra; Borges, Daniel L. Gallindo; Welz, Bernhard; Heitmann, Uwe; Curtius, Adilson Jose

    2005-01-01

    Two procedures for the determination of Co in biological samples by graphite furnace atomic absorption spectrometry (GF AAS) were compared: solid sampling (SS) and alkaline treatment with tetramethylammonium hydroxide (TMAH) using two different instruments for the investigation: a conventional line-source (LS) atomic absorption spectrometer and a prototype high-resolution continuum source atomic absorption spectrometer. For the direct introduction of the solid samples, certified reference materials (CRM) were ground to a particle size ≤50 μm. Alkaline treatment was carried out by placing about 250 mg of the sample in polypropylene flasks, adding 2 mL of 25% m/v tetramethylammonium hydroxide and de-ionized water. Due to its unique capacity of providing a 3-D spectral plot, a high-resolution continuum source (HR-CS) graphite furnace atomic absorption spectrometry was used as a tool to evaluate potential spectral interferences, including background absorption for both sample introduction procedures, revealing that a continuous background preceded the atomic signal for pyrolysis temperatures lower than 700 deg. C. Molecular absorption bands with pronounced rotational fine structure appeared for atomization temperatures >1800 deg. C probably as a consequence of the formation of PO. After optimization had been carried out using high resolution continuum source atomic absorption spectrometry, the optimized conditions were adopted also for line-source atomic absorption spectrometry. Six biological certified reference materials were analyzed, with calibration against aqueous standards, resulting in agreement with the certified values (according to the t-test for a 95% confidence level) and in detection limits as low as 5 ng g -1

  20. Laser absorption spectroscopy of water vapor confined in nanoporous alumina: wall collision line broadening and gas diffusion dynamics.

    Science.gov (United States)

    Svensson, Tomas; Lewander, Märta; Svanberg, Sune

    2010-08-02

    We demonstrate high-resolution tunable diode laser absorption spectroscopy (TDLAS) of water vapor confined in nanoporous alumina. Strong multiple light scattering results in long photon pathlengths (1 m through a 6 mm sample). We report on strong line broadening due to frequent wall collisions (gas-surface interactions). For the water vapor line at 935.685 nm, the HWHM of confined molecules are about 4.3 GHz as compared to 2.9 GHz for free molecules (atmospheric pressure). Gas diffusion is also investigated, and in contrast to molecular oxygen (that moves rapidly in and out of the alumina), the exchange of water vapor is found very slow.

  1. The analysis of the external factors influence on the efficiency of the absorption heat pumps inclusion in the scheme of a two-stage line installation of a STP

    Directory of Open Access Journals (Sweden)

    Luzhkovoy Dmitriy S.

    2017-01-01

    Full Text Available The article deals with a comparative analysis of the efficiency of a two-stage line installation in a heating turbine before and after the inclusion of absorption heat pumps into its scheme with a decrease in the outside air temperature. The research shows the dependence of the efficiency of the line installation on its heat load while using AHP in its scheme, as well as on the heat conversion factor of the absorption heat pumps.

  2. Absorption spectrum of Iodine around 5915 A

    International Nuclear Information System (INIS)

    1990-01-01

    The iodine absorption spectrum around 5915 A is of interest for many authors especially the hyperfine structure of the iodine line. Lodine absorption spectrum was obtained due to the interaction of iodine vapour with dye laser [(R6G) (0.5A) scanning range around 5915 A] which is pumped by(Ar + )laser absorption spectrum. The decrease in the peak of the transmission line around 5915 A shows the signal futher decreased by heating the iodine cell. This analysis has been done using a monochromator

  3. Emission and Absorption in the M87 LINER

    Science.gov (United States)

    Sabra, Bassem M.; Shields, Joseph C.; Ho, Luis C.; Barth, Aaron J.; Filippenko, Alexei V.

    2003-02-01

    The nucleus of M87 displays a LINER spectrum at optical wavelengths, with a nuclear disk of nebulosity that is resolved by the Hubble Space Telescope (HST). We present new results from optical and ultraviolet spectra of the central ~40 pc as measured by HST. In contrast with previous results for the extended disk, the emission-line spectrum of the central region is best reproduced by a multicomponent photoionization scenario, rather than shock heating. The nebular properties as well as energetic considerations suggest a transition on scales of several tens of parsecs, from predominantly photoionization by a central accretion source to shock ionization within the disk. If this source is at all representative, it suggests that many LINERs may be composite in terms of the energetic processes that give rise to the emission spectrum. We also report measurements of resonance-line absorption for the nucleus. The absorption spectrum, like the emission lines, is characterized by low ionization. The absorption-line measurements coupled with independent constraints suggest a total hydrogen column density of 1019-1020 cm-2, outflowing from the galaxy center with a velocity of ~126 km s-1. The kinematic signature of an outflow, along with evidence that the absorber covers the power-law continuum source but not the emission-line clouds, suggests that the absorbing matter is related to accretion phenomena in the nucleus. The presence of such an outflow resembles similar behavior in luminous active galactic nuclei, although the low ionization that characterizes LINERs is probably indicative of a different mode of accretion in these sources. Based on observations with the NASA/ESA Hubble Space Telescope obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

  4. Genetic analysis of processed in-line mastitis indicator data

    DEFF Research Database (Denmark)

    Sørensen, Lars Peter; Løvendahl, Peter

    2013-01-01

    indicates high risk of mastitis. The EMR values were summarized for each cow using the log-transformed median EMR. A second trait was defined as the median of the log-transformed SCC values from 5 to 305 d in milk. A bivariate animal model was used for estimation of co-variance components for the 2 traits......The aim of this study was to estimate heritability of elevated mastitis risk (EMR), a trait derived from in-line measurements of cell counts expressing risk of mastitis on a continuous scale, and its genetic correlation with in-line somatic cell counts. Log-transformed somatic cell counts (SCC; n...... = 855,181) based on in-line measurements (OCC, DeLaval, Sweden) in automatic milking systems were collected from 2007 to2013 in 7 herds from a total of 1986 first and second parity cows (5 to 305 d in milk). Only data from the lactation with most measurements was used from each cow. A bio-model based...

  5. Microwave measurements of the absolute values of absorption by water vapour in the atmosphere.

    Science.gov (United States)

    Hogg, D C; Guiraud, F O

    1979-05-31

    MEASUREMENT of the absolute value of absorption by water vapour at microwave frequencies is difficult because the effect is so small. Far in the wings of the absorption lines, in the so-called 'windows' of the spectrum, it is especially difficult to achieve high accuracy in the free atmosphere. But it is in these windows that the behaviour of the absorption is important from both applied and scientific points of view. Satellite communications, remote sensing of the atmosphere, and radioastronomy, are all influenced by this behaviour. Measurements on an Earth-space path are reported here; the results indicate a nonlinear relationship between absorption and water-vapour content.

  6. Zeeman atomic absorption spectroscopy

    International Nuclear Information System (INIS)

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

    1980-01-01

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

  7. Wave energy absorption by ducks

    OpenAIRE

    Kurniawan, Adi

    2017-01-01

    We study the absorption of wave energy by a single and multiple cam-shaped bodies referred to as ducks. Numerical models are developed under the assumptions of linear theory. We consider wave absorption by a single duck as well as by two lines of ducks meeting at an angle.

  8. Wave energy absorption by ducks

    DEFF Research Database (Denmark)

    Kurniawan, Adi

    2018-01-01

    We study the absorption of wave energy by a single and multiple cam-shaped bodies referred to as ducks. Numerical models are developed under the assumptions of linear theory. We consider wave absorption by a single duck as well as by two lines of ducks meeting at an angle....

  9. A New Window into Escaping Exoplanet Atmospheres: 10830 Å Line of Helium

    Science.gov (United States)

    Oklopčić, Antonija; Hirata, Christopher M.

    2018-03-01

    Observational evidence for escaping exoplanet atmospheres has been obtained for a few exoplanets to date. It comes from strong transit signals detected in the ultraviolet, most notably in the wings of the hydrogen Lyα (Lyα) line. However, the core of the Lyα line is often heavily affected by interstellar absorption and geocoronal emission, limiting the information about the atmosphere that can be extracted from that part of the spectrum. Transit observations in atomic lines that are (a) sensitive enough to trace the rarefied gas in the planetary wind and (b) do not suffer from significant extinction by the interstellar medium could enable more detailed observations, and thus provide better constraints on theoretical models of escaping atmospheres. The absorption line of a metastable state of helium at 10830 Å could satisfy both of these conditions for some exoplanets. We develop a simple 1D model of escaping planetary atmospheres containing hydrogen and helium. We use it to calculate the density profile of helium in the 23S metastable excited state and the expected in-transit absorption at 10830 Å for two exoplanets known to have escaping atmospheres. Our results indicate that exoplanets similar to GJ 436b and HD 209458b should exhibit enhanced transit depths at 10830 Å, with ∼8% and ∼2% excess absorption in the line core, respectively.

  10. On the nature of absorption features toward nearby stars

    Science.gov (United States)

    Kohl, S.; Czesla, S.; Schmitt, J. H. M. M.

    2016-06-01

    Context. Diffuse interstellar absorption bands (DIBs) of largely unknown chemical origin are regularly observed primarily in distant early-type stars. More recently, detections in nearby late-type stars have also been claimed. These stars' spectra are dominated by stellar absorption lines. Specifically, strong interstellar atomic and DIB absorption has been reported in τ Boo. Aims: We test these claims by studying the strength of interstellar absorption in high-resolution TIGRE spectra of the nearby stars τ Boo, HD 33608, and α CrB. Methods: We focus our analysis on a strong DIB located at 5780.61 Å and on the absorption of interstellar Na. First, we carry out a differential analysis by comparing the spectra of the highly similar F-stars, τ Boo and HD 33608, whose light, however, samples different lines of sight. To obtain absolute values for the DIB absorption, we compare the observed spectra of τ Boo, HD 33608, and α CrB to PHOENIX models and carry out basic spectral modeling based on Voigt line profiles. Results: The intercomparison between τ Boo and HD 33608 reveals that the difference in the line depth is 6.85 ± 1.48 mÅ at the DIB location which is, however, unlikely to be caused by DIB absorption. The comparison between PHOENIX models and observed spectra yields an upper limit of 34.0 ± 0.3 mÅ for any additional interstellar absorption in τ Boo; similar results are obtained for HD 33608 and α CrB. For all objects we derive unrealistically large values for the radial velocity of any presumed interstellar clouds. In τ Boo we find Na D absorption with an equivalent width of 0.65 ± 0.07 mÅ and 2.3 ± 0.1 mÅ in the D2 and D1 lines. For the other Na, absorption of the same magnitude could only be detected in the D2 line. Our comparisons between model and data show that the interstellar absorption toward τ Boo is not abnormally high. Conclusions: We find no significant DIB absorption in any of our target stars. Any differences between modeled and

  11. The CO_2 absorption spectrum in the 2.3 µm transparency window by high sensitivity CRDS: (II) Self-absorption continuum

    International Nuclear Information System (INIS)

    Mondelain, D.; Vasilchenko, S.; Čermák, P.; Kassi, S.; Campargue, A.

    2017-01-01

    The CO_2 absorption continuum near 2.3 µm is determined for a series of sub atmospheric pressures (250–750 Torr) by high sensitivity Cavity Ring Down Spectroscopy. An experimental procedure consisting in injecting successively a gas flow of CO_2 and synthetic air, keeping constant the gas pressure in the CRDS cell, has been developed. This procedure insures a high stability of the spectra baseline by avoiding changes of the optical alignment due to pressure changes. The CO_2 continuum was obtained as the difference between the CO_2 absorption coefficient and a local lines simulation using a Voigt profile truncated at ±25 cm"−"1. Following the results of the preceding analysis of the CO_2 rovibrational lines (Vasilchenko S et al. J Quant Spectrosc Radiat Transfer (10.1016/j.jqsrt.2016.07.002), a CO_2 line list with intensities obtained by variational calculations and empirical line positions was preferred to the HITRAN line list. A quadratic pressure dependence of the absorption continuum is observed, with an average binary absorption coefficient increasing from 2 to 4×10"−"8 cm"−"1 amagat"−"2 between 4320 and 4380 cm"−"1. The obtained continuum is found in good agreement with a previous measurement using much higher densities (20 amagat) and a low resolution grating spectrograph and is consistent with values currently used in the analysis of Venus spectra. - Highlights: • The CO_2 absorption continuum is measured by CRDS in the 2.3 µm window. • The achieved sensitivity and stability allow measurements at sub-atmospheric pressure. • The absorption coefficient is on the order of 3×10"−"8 cm"−"1 amagat"−"2 near 4350 cm"−"1. • A good agreement is obtained with previous results at much higher density (20 amagat).

  12. Terahertz in-line digital holography of human hepatocellular carcinoma tissue

    Science.gov (United States)

    Rong, Lu; Latychevskaia, Tatiana; Chen, Chunhai; Wang, Dayong; Yu, Zhengping; Zhou, Xun; Li, Zeyu; Huang, Haochong; Wang, Yunxin; Zhou, Zhou

    2015-02-01

    Terahertz waves provide a better contrast in imaging soft biomedical tissues than X-rays, and unlike X-rays, they cause no ionisation damage, making them a good option for biomedical imaging. Terahertz absorption imaging has conventionally been used for cancer diagnosis. However, the absorption properties of a cancerous sample are influenced by two opposing factors: an increase in absorption due to a higher degree of hydration and a decrease in absorption due to structural changes. It is therefore difficult to diagnose cancer from an absorption image. Phase imaging can thus be critical for diagnostics. We demonstrate imaging of the absorption and phase-shift distributions of 3.2 mm × 2.3 mm × 30-μm-thick human hepatocellular carcinoma tissue by continuous-wave terahertz digital in-line holography. The acquisition time of a few seconds for a single in-line hologram is much shorter than that of other terahertz diagnostic techniques, and future detectors will allow acquisition of meaningful holograms without sample dehydration. The resolution of the reconstructions was enhanced by sub-pixel shifting and extrapolation. Another advantage of this technique is its relaxed minimal sample size limitation. The fibrosis indicated in the phase distribution demonstrates the potential of terahertz holographic imaging to obtain a more objective, early diagnosis of cancer.

  13. Terahertz in-line digital holography of human hepatocellular carcinoma tissue.

    Science.gov (United States)

    Rong, Lu; Latychevskaia, Tatiana; Chen, Chunhai; Wang, Dayong; Yu, Zhengping; Zhou, Xun; Li, Zeyu; Huang, Haochong; Wang, Yunxin; Zhou, Zhou

    2015-02-13

    Terahertz waves provide a better contrast in imaging soft biomedical tissues than X-rays, and unlike X-rays, they cause no ionisation damage, making them a good option for biomedical imaging. Terahertz absorption imaging has conventionally been used for cancer diagnosis. However, the absorption properties of a cancerous sample are influenced by two opposing factors: an increase in absorption due to a higher degree of hydration and a decrease in absorption due to structural changes. It is therefore difficult to diagnose cancer from an absorption image. Phase imaging can thus be critical for diagnostics. We demonstrate imaging of the absorption and phase-shift distributions of 3.2 mm × 2.3 mm × 30-μm-thick human hepatocellular carcinoma tissue by continuous-wave terahertz digital in-line holography. The acquisition time of a few seconds for a single in-line hologram is much shorter than that of other terahertz diagnostic techniques, and future detectors will allow acquisition of meaningful holograms without sample dehydration. The resolution of the reconstructions was enhanced by sub-pixel shifting and extrapolation. Another advantage of this technique is its relaxed minimal sample size limitation. The fibrosis indicated in the phase distribution demonstrates the potential of terahertz holographic imaging to obtain a more objective, early diagnosis of cancer.

  14. Atmospheric pressure and temperature profiling using near IR differential absorption lidar

    Science.gov (United States)

    Korb, C. L.; Schwemmer, G. K.; Dombrowski, M.; Weng, C. Y.

    1983-01-01

    The present investigation is concerned with differential absorption lidar techniques for remotely measuring the atmospheric temperature and pressure profile, surface pressure, and cloud top pressure-height. The procedure used in determining the pressure is based on the conduction of high-resolution measurements of absorption in the wings of lines in the oxygen A band. Absorption with respect to these areas is highly pressure sensitive in connection with the mechanism of collisional line broadening. The method of temperature measurement utilizes a determination of the absorption at the center of a selected line in the oxygen A band which originates from a quantum state with high ground state energy.

  15. 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.

  16. The Frequency of Intrinsic X-Ray Weakness among Broad Absorption Line Quasars

    Science.gov (United States)

    Liu, Hezhen; Luo, B.; Brandt, W. N.; Gallagher, S. C.; Garmire, G. P.

    2018-06-01

    We present combined ≈14–37 ks Chandra observations of seven z = 1.6–2.7 broad absorption line (BAL) quasars selected from the Large Bright Quasar Survey (LBQS). These seven objects are high-ionization BAL (HiBAL) quasars, and they were undetected in the Chandra hard band (2–8 keV) in previous observations. The stacking analyses of previous Chandra observations suggested that these seven objects likely contain some candidates for intrinsically X-ray weak BAL quasars. With the new Chandra observations, six targets are detected. We calculate their effective power-law photon indices and hard-band flux weakness, and find that two objects, LBQS 1203+1530 and LBQS 1442–0011, show soft/steep spectral shapes ({{{Γ }}}eff}={2.2}-0.9+0.9 and {1.9}-0.8+0.9) and significant X-ray weakness in the hard band (by factors of ≈15 and 12). We conclude that the two HiBAL quasars are good candidates for intrinsically X-ray weak BAL quasars. The mid-infrared-to-ultraviolet spectral energy distributions of the two candidates are consistent with those of typical quasars. We constrain the fraction of intrinsically X-ray weak active galactic nuclei (AGNs) among HiBAL quasars to be ≈7%–10% (2/29–3/29), and we estimate it is ≈6%–23% (2/35–8/35) among the general BAL quasar population. Such a fraction is considerably larger than that among non-BAL quasars, and we suggest that intrinsically X-ray weak quasars are preferentially observed as BAL quasars. Intrinsically X-ray weak AGNs likely comprise a small minority of the luminous type 1 AGN population, and they should not affect significantly the completeness of these AGNs found in deep X-ray surveys.

  17. Survey for C-Band High Spectral Lines with the Arecibo Telescope

    Science.gov (United States)

    Tan, Wei Siang

    High-mass stars have masses greater than 8 solar masses and are the main source of heavy elements such as iron in the interstellar medium. This type of stars form in giant molecular clouds. Studying the molecular environment in star-forming regions is crucial to understand the physical structure and conditions that lead to the formation of high-mass stars. This thesis presents observations conducted with the 305m Arecibo Telescope in Puerto Rico of twelve high-mass star forming regions. Every source was observed in multiple transitions of molecular species including CH, CH3OH, H2CS, and OH lines, and a radio recombination line. The observations were conducted with the C-Band High receiver of the Arecibo Telescope in the frequency range of 6.0 to 7.4GHz. The goals of the observations were to investigate the detectability of different molecular species (including new possible molecular masers) and obtain high sensitivity observations of the 6.7GHz CH3OH line to detect absorption and use it as a probe of the kinematics of the molecular material with respect to the ionized gas. Among the results of the observations, we report detection of 6.7GHz CH3OH masers toward nine regions, OH masers toward five sources, 6.7GHz CH3OH absorption toward four sources (including tentative detections), and detection of H2CS toward the star forming region G34.26+0.15. We also found a variable and recurrent 6.7GHz CH3OH maser in G45.12+0.13. The 6.7GHz CH 3OH and 6278.65MHz H2CS absorption lines were modeled using the radiative transfer code RADEX to investigate the physical conditions of the molecular clouds responsible for the absorption lines. Our analysis of the absorption lines supports the interpretation that the spectral lines are tracing molecular envelopes of HII regions. In the case of 6.7GHz CH 3OH absorption, our results and data from an extensive literature review indicate that absorption is rare, but that a population of 6.7GHz CH 3OH absorbers may be present at levels

  18. Bismuth as a general internal standard for lead in atomic absorption spectrometry.

    Science.gov (United States)

    Bechlin, Marcos A; Fortunato, Felipe M; Ferreira, Edilene C; Gomes Neto, José A; Nóbrega, Joaquim A; Donati, George L; Jones, Bradley T

    2014-06-11

    Bismuth was evaluated as internal standard for Pb determination by line source flame atomic absorption spectrometry (LS FAAS), high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS) and line source graphite furnace atomic absorption spectrometry (LS GFAAS). Analysis of samples containing different matrices indicated close relationship between Pb and Bi absorbances. Correlation coefficients of calibration curves built up by plotting A(Pb)/A(Bi)versus Pb concentration were higher than 0.9953 (FAAS) and higher than 0.9993 (GFAAS). Recoveries of Pb improved from 52-118% (without IS) to 97-109% (IS, LS FAAS); 74-231% (without IS) to 96-109% (IS, HR-CS FAAS); and 36-125% (without IS) to 96-110% (IS, LS GFAAS). The relative standard deviations (n=12) were reduced from 0.6-9.2% (without IS) to 0.3-4.3% (IS, LS FAAS); 0.7-7.7% (without IS) to 0.1-4.0% (IS, HR-CS FAAS); and 2.1-13% (without IS) to 0.4-5.9% (IS, LS GFAAS). Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Iron K Features in the Quasar E 1821+643: Evidence for Gravitationally Redshifted Absorption?

    Science.gov (United States)

    Yaqoob, Tahir; Serlemitsos, Peter

    2005-01-01

    We report a Chandra high-energy grating detection of a narrow, redshifted absorption line superimposed on the red wing of a broad Fe K line in the z = 0.297 quasar E 1821+643. The absorption line is detected at a confidence level, estimated by two different methods, in the range approx. 2 - 3 sigma. Although the detection significance is not high enough to exclude a non-astrophysical origin, accounting for the absorption feature when modeling the X-ray spectrum implies that the Fe-K emission line is broad, and consistent with an origin in a relativistic accretion disk. Ignoring the apparent absorption feature leads to the conclusion that the Fe-K emission line is narrower, and also affects the inferred peak energy of the line (and hence the inferred ionization state of Fe). If the absorption line (at approx. 6.2 keV in the quasar frame) is real, we argue that it could be due to gravitationally redshifted Fe XXV or Fe XXVI resonance absorption within approx. 10 - 20 gravitational radii of the putative central black hole. The absorption line is not detected in earlier ASCA and Chandra low-energy grating observations, but the absorption line is not unequivocally ruled out by these data. The Chandra high-energy grating Fe-K emission line is consistent with an origin predominantly in Fe I-XVII or so. In an ASCA observation eight years earlier, the Fe-K line peaked at approx. 6.6 keV, closer to the energies of He-like Fe triplet lines. Further, in a Chandra low-energy grating observation the Fe-K line profile was double-peaked, one peak corresponding to Fe I-XVII or so, the other peak to Fe XXVI Ly alpha. Such a wide range in ionization state of Fe is not ruled out by the HEG and ASCA data either, and is suggestive of a complex structure for the line-emitter.

  20. 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 ...

  1. The effect of ISM absorption on stellar activity measurements and its relevance for exoplanet studies

    Science.gov (United States)

    Fossati, L.; Marcelja, S. E.; Staab, D.; Cubillos, P. E.; France, K.; Haswell, C. A.; Ingrassia, S.; Jenkins, J. S.; Koskinen, T.; Lanza, A. F.; Redfield, S.; Youngblood, A.; Pelzmann, G.

    2017-05-01

    Past ultraviolet and optical observations of stars hosting close-in Jupiter-mass planets have shown that some of these stars present an anomalously low chromospheric activity, significantly below the basal level. For the hot Jupiter planet host WASP-13, observations have shown that the apparent lack of activity is possibly caused by absorption from the intervening interstellar medium (ISM). Inspired by this result, we study the effect of ISM absorption on activity measurements (S and log R 'HK indices) for main-sequence late-type stars. To this end, we employ synthetic stellar photospheric spectra combined with varying amounts of chromospheric emission and ISM absorption. We present the effect of ISM absorption on activity measurements by varying several instrumental (spectral resolution), stellar (projected rotational velocity, effective temperature, and chromospheric emission flux), and ISM parameters (relative velocity between stellar and ISM Ca II lines, broadening b-parameter, and Ca II column density). We find that for relative velocities between the stellar and ISM lines smaller than 30-40 km s-1 and for ISM Ca II column densities log NCaII ⪆ 12, the ISM absorption has a significant influence on activity measurements. Direct measurements and three dimensional maps of the Galactic ISM absorption indicate that an ISM Ca II column density of log NCaII = 12 is typically reached by a distance of about 100 pc along most sight lines. In particular, for a Sun-like star lying at a distance greater than 100 pc, we expect a depression (bias) in the log R'HK value larger than 0.05-0.1 dex, about the same size as the typical measurement and calibration uncertainties on this parameter. This work shows that the bias introduced by ISM absorption must always be considered when measuring activity for stars lying beyond 100 pc. We also consider the effect of multiple ISM absorption components. We discuss the relevance of this result for exoplanet studies and revise the

  2. DETECTING THE WARM-HOT INTERGALACTIC MEDIUM THROUGH X-RAY ABSORPTION LINES

    Energy Technology Data Exchange (ETDEWEB)

    Yao Yangsen; Shull, J. Michael; Cash, Webster [Center for Astrophysics and Space Astronomy, Department of Astrophysical and Planetary Sciences, University of Colorado, 389 UCB, Boulder, CO 80309 (United States); Wang, Q. Daniel, E-mail: yaoys@colorado.edu [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States)

    2012-02-20

    The warm-hot intergalactic medium (WHIM) at temperatures 10{sup 5}-10{sup 7} K is believed to contain 30%-50% of the baryons in the local universe. However, all current X-ray detections of the WHIM at redshifts z > 0 are of low statistical significance ({approx}< 3{sigma}) and/or controversial. In this work, we aim to establish the detection limits of current X-ray observatories and explore requirements for next-generation X-ray telescopes for studying the WHIM through X-ray absorption lines. We analyze all available grating observations of Mrk 421 and obtain spectra with signal-to-noise ratios (S/Ns) of {approx}90 and 190 per 50 mA spectral bin from Chandra and XMM-Newton observations, respectively. Although these spectra are two of the best ever collected with Chandra and XMM-Newton, we cannot confirm the two WHIM systems reported by Nicastro et al. in 2005. Our bootstrap simulations indicate that spectra with such high S/N cannot constrain the WHIM with O VII column densities N{sub Ovii}{approx}10{sup 15} cm{sup -2} (corresponding to an equivalent width of 2.5 mA for a Doppler velocity of 50 km s{sup -1}) at {approx}> 3{sigma} significance level. The simulation results also suggest that it would take >60 Ms for Chandra and 140 Ms for XMM-Newton to measure the N{sub Ovii} at {>=}4{sigma} from a spectrum of a background QSO with flux of {approx}0.2 mCrab (1 Crab = 2 Multiplication-Sign 10{sup -8} erg s{sup -1} cm{sup -2} at 0.5-2 keV). Future X-ray spectrographs need to be equipped with spectral resolution R {approx} 4000 and effective area A {>=} 100 cm{sup 2} to accomplish the similar constraints with an exposure time of {approx}2 Ms and would require {approx}11 Ms to survey the 15 QSOs with flux {approx}> 0.2 mCrab along which clear intergalactic O VI absorbers have been detected.

  3. A Survey of Metal Lines at High Redshift. II. SDSS Absorption Line Studies—O VI Line Density, Space Density, and Gas Metallicity at z abs ~ 3.0

    Science.gov (United States)

    Frank, S.; Mathur, S.; Pieri, M.; York, D. G.

    2010-09-01

    We have analyzed a large data set of O VI absorber candidates found in the spectra of 3702 Sloan Digital Sky Survey (SDSS) quasars, focusing on a subsample of 387 active galactic nuclei sight lines with an average S/N >=5.0, allowing for the detection of absorbers above a rest-frame equivalent width limit of W r >= 0.19 Å for the O VI 1032 Å component. Accounting for random interlopers mimicking an O VI doublet, we derive for the first time a secure lower limit for the redshift number density ΔN/Δz for redshifts z abs >= 2.8. With extensive Monte Carlo simulations, we quantify the losses of absorbers due to blending with the ubiquitous Lyα forest lines and estimate the success rate of retrieving each individual candidate as a function of its redshift, the emission redshift of the quasar, the strength of the absorber, and the measured signal-to-noise ratio (S/N) of the spectrum by modeling typical Lyman forest spectra. These correction factors allow us to derive the "incompleteness and S/N-corrected" redshift number densities of O VI absorbers: ΔN O VI,c /Δzc (2.8 secure lower limit for the contribution of O VI to the closure mass density at the redshifts probed here: ΩO VI (2.8 = 1.9 × 10-8 h -1. We show that the strong lines we probe account for over 65% of the mass in the O VI absorbers; the weak absorbers, while dominant in line number density, do not contribute significantly to the mass density. Making a conservative assumption about the ionization fraction, {O VI}/{O}, and adopting the Anders & Grevesse solar abundance values, we derive the mean metallicity of the gas probed in our search: ζ(2.8 = 3.6 × 10-4 h, in good agreement with other studies. These results demonstrate that large spectroscopic data sets such as SDSS can play an important role in QSO absorption line studies, in spite of the relatively low resolution.

  4. A SURVEY OF METAL LINES AT HIGH REDSHIFT. II. SDSS ABSORPTION LINE STUDIES-O VI LINE DENSITY, SPACE DENSITY, AND GAS METALLICITY AT zabs ∼ 3.0

    International Nuclear Information System (INIS)

    Frank, S.; Mathur, S.; Pieri, M.; York, D. G.

    2010-01-01

    We have analyzed a large data set of O VI absorber candidates found in the spectra of 3702 Sloan Digital Sky Survey (SDSS) quasars, focusing on a subsample of 387 active galactic nuclei sight lines with an average S/N ≥5.0, allowing for the detection of absorbers above a rest-frame equivalent width limit of W r ≥ 0.19 A for the O VI 1032 A component. Accounting for random interlopers mimicking an O VI doublet, we derive for the first time a secure lower limit for the redshift number density ΔN/Δz for redshifts z abs ≥ 2.8. With extensive Monte Carlo simulations, we quantify the losses of absorbers due to blending with the ubiquitous Lyα forest lines and estimate the success rate of retrieving each individual candidate as a function of its redshift, the emission redshift of the quasar, the strength of the absorber, and the measured signal-to-noise ratio (S/N) of the spectrum by modeling typical Lyman forest spectra. These correction factors allow us to derive the 'incompleteness and S/N-corrected' redshift number densities of O VI absorbers: ΔN O V I,c /Δz c (2.8 O V I,c /Δz c (3.2 O V I,c /Δz c (3.6 O V I (2.8 -8 h -1 . We show that the strong lines we probe account for over 65% of the mass in the O VI absorbers; the weak absorbers, while dominant in line number density, do not contribute significantly to the mass density. Making a conservative assumption about the ionization fraction, O VI /O, and adopting the Anders and Grevesse solar abundance values, we derive the mean metallicity of the gas probed in our search: ζ(2.8 -4 h, in good agreement with other studies. These results demonstrate that large spectroscopic data sets such as SDSS can play an important role in QSO absorption line studies, in spite of the relatively low resolution.

  5. Far-wing absorption in Na-Ar collision

    International Nuclear Information System (INIS)

    Kulander, K.C.

    1985-01-01

    Collision-induced absorption and emission at wavelengths well removed from line center play important roles in many atomic and molecular processes. The authors have developed the theory and computer codes to calculate exact quantum mechanical cross sections for these optical and radiative collisions between atoms. The authors also have produced a quasi-classical model that can efficiently generate accurate absorption cross sections. This model cannot, however, give branching ratios for the final-state populations. Their codes and model can be used to study the propagation of nearly resonant light through gaseous media and to calculate accurate gain and absorption cross sections for the far wings of atomic transitions. The authors have used their theory to study the collision-induced absorption by sodium in argon for wavelengths in the vicinity of the resonance lines D 1 and D 2

  6. The CO2 absorption spectrum in the 2.3 μm transparency window by high sensitivity CRDS: (II) Self-absorption continuum

    Science.gov (United States)

    Mondelain, D.; Vasilchenko, S.; Čermák, P.; Kassi, S.; Campargue, A.

    2017-01-01

    The CO2 absorption continuum near 2.3 μm is determined for a series of sub atmospheric pressures (250-750 Torr) by high sensitivity Cavity Ring Down Spectroscopy. An experimental procedure consisting in injecting successively a gas flow of CO2 and synthetic air, keeping constant the gas pressure in the CRDS cell, has been developed. This procedure insures a high stability of the spectra baseline by avoiding changes of the optical alignment due to pressure changes. The CO2 continuum was obtained as the difference between the CO2 absorption coefficient and a local lines simulation using a Voigt profile truncated at ±25 cm-1. Following the results of the preceding analysis of the CO2 rovibrational lines (Vasilchenko S et al. J Quant Spectrosc Radiat Transfer 10.1016/j.jqsrt.2016.07.002, a CO2 line list with intensities obtained by variational calculations and empirical line positions was preferred to the HITRAN line list. A quadratic pressure dependence of the absorption continuum is observed, with an average binary absorption coefficient increasing from 2 to 4×10-8 cm-1 amagat-2 between 4320 and 4380 cm-1. The obtained continuum is found in good agreement with a previous measurement using much higher densities (20 amagat) and a low resolution grating spectrograph and is consistent with values currently used in the analysis of Venus spectra.

  7. Evaluation of Drought response in Some Rice Mutant Lines Using Stress Tolerance Indices

    Directory of Open Access Journals (Sweden)

    H Aminpanah

    2018-05-01

    Full Text Available Introduction Drought is a major problem that limits the adoption of high-yielding rice varieties in drought-prone rainfed rice environments. To improve crop productivity, it is necessary to understand the mechanism of plant responses to drought conditions with the ultimate goal of improving crop performance in the vast areas of the world where rainfall is limiting or unreliable. Safaei Chaeikar et al. (2008 reported that MP, GMP, HM and STI indices, which showed the highest correlation with grain yield under both optimal and stress conditions, can be used as the best indices to introduce drought-tolerant genotypes in rice breeding programs. They also were introduced Nemat, Sepidrood, IR64, IR50 and Bejar genotypes as tolerant varieties. The present study was conducted to determine how drought affects grain yield in rice mutant lines and also to test this hypothesis in order to identify the most suitable indices/genotypes. Materials and Methods A field trial was conducted at Iranian Rice Research Centers in North of Iran, Rasht (latitude 37◦28', longitude 49◦28'E and altitude 7m below the sea level, during the 2014-2015 growing season. The seeds were sown in a nursery on the 10 May and 25 day old seedlings were transplanted to the field. Two separately experiment was carried out under reproductive stage drought stress and controlled conditions based on randomized complete block design with three replications, in four-row plots of three m length. Transplanting was done using 1 seedling per hill; at hill spacing of 25 cm × 25 cm. 18 rice genotypes were consisted 14 M5 mutant lines and their four parental cultivars. Results and Discussion Analysis of variance indicated significant effects of drought stress, genotype and interaction effects of two factors on grain yield, plant height, flag leaf area, tiller number and grain fertility percentage. Drought stress at reproductive stage caused reduction in grain yield (59.47%, grain fertility

  8. Weak Hard X-Ray Emission from Two Broad Absorption Line Quasars Observed with NuStar: Compton-Thick Absorption or Intrinsic X-Ray Weakness?

    Science.gov (United States)

    Luo, B.; Brandt, W. N.; Alexander, D. M.; Harrison, F. A.; Stern, D.; Bauer, F. E.; Boggs, S. E.; Christensen, F. E.; Comastri, A.; Craig, W. W..; hide

    2013-01-01

    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 approx. or equal to 400-600 hard X-ray (is greater than or equal to 10 keV) photons with NuSTAR, provided that these photons are not significantly absorbed N(sub H) is less than or equal to 10(exp24) cm(exp-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) 7 × 10(exp 24) cm(exp-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 Ka 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%.

  9. 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%.

  10. 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.

  11. The Fishery Performance Indicators: A Management Tool for Triple Bottom Line Outcomes

    Science.gov (United States)

    Anderson, James L.; Anderson, Christopher M.; Chu, Jingjie; Meredith, Jennifer; Asche, Frank; Sylvia, Gil; Smith, Martin D.; Anggraeni, Dessy; Arthur, Robert; Guttormsen, Atle; McCluney, Jessica K.; Ward, Tim; Akpalu, Wisdom; Eggert, Håkan; Flores, Jimely; Freeman, Matthew A.; Holland, Daniel S.; Knapp, Gunnar; Kobayashi, Mimako; Larkin, Sherry; MacLauchlin, Kari; Schnier, Kurt; Soboil, Mark; Tveteras, Sigbjorn; Uchida, Hirotsugu; Valderrama, Diego

    2015-01-01

    Pursuit of the triple bottom line of economic, community and ecological sustainability has increased the complexity of fishery management; fisheries assessments require new types of data and analysis to guide science-based policy in addition to traditional biological information and modeling. We introduce the Fishery Performance Indicators (FPIs), a broadly applicable and flexible tool for assessing performance in individual fisheries, and for establishing cross-sectional links between enabling conditions, management strategies and triple bottom line outcomes. Conceptually separating measures of performance, the FPIs use 68 individual outcome metrics—coded on a 1 to 5 scale based on expert assessment to facilitate application to data poor fisheries and sectors—that can be partitioned into sector-based or triple-bottom-line sustainability-based interpretative indicators. Variation among outcomes is explained with 54 similarly structured metrics of inputs, management approaches and enabling conditions. Using 61 initial fishery case studies drawn from industrial and developing countries around the world, we demonstrate the inferential importance of tracking economic and community outcomes, in addition to resource status. PMID:25946194

  12. INVESTIGATION OF MICROPROCESSOR CURRENT PROTECTION LINES WITH IMPROVED INDICES OF TECHNICAL PERFECTION

    Directory of Open Access Journals (Sweden)

    E. V. Buloichyk

    2014-01-01

    Full Text Available Technical perfection improvement of microprocessor current protection of distribution networks lines is provided by introduction of asymmetrical fault mode determination and fault location functions in the algorithm of its functioning. As a result of computing experiment the basic indices of the technical perfection of current protection have been obtained in the paper. The paper proves high efficiency of the proposed methods that ensure selective and proper operation in the different modes of the controlled line.

  13. 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.

  14. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Hager, J. D., E-mail: hager@lanl.gov; Lanier, N. E.; Kline, J. L.; Flippo, K. A. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Bruns, H. C.; Schneider, M.; Saculla, M.; McCarville, T. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

    2014-11-15

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

  16. Temperature Dependences of Mechanisms Responsible for the Water-Vapor Continuum Absorption

    Science.gov (United States)

    Ma, Qiancheng

    2014-01-01

    The water-vapor continuum absorption plays an important role in the radiative balance in the Earth's atmosphere. It has been experimentally shown that for ambient atmospheric conditions, the continuum absorption scales quadratically with the H2O number density and has a strong, negative temperature dependence (T dependence). Over the years, there have been three different theoretical mechanisms postulated: far-wings of allowed transition lines, water dimers, and collision-induced absorption. The first mechanism proposed was the accumulation of absorptions from the far-wings of the strong allowed transition lines. Later, absorption by water dimers was proposed, and this mechanism provides a qualitative explanation for the continuum characters mentioned above. Despite the improvements in experimental data, at present there is no consensus on which mechanism is primarily responsible for the continuum absorption.

  17. 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.

  18. Radio recombination lines from H II regions

    International Nuclear Information System (INIS)

    Silverglate, P.R.

    1978-01-01

    Radio recombination lines have been observed from forty-six H II regions. The Arecibo 1000-foot radio telescope was used to provide high sensitivity and high angular resolution at 1400 MHz (gain approx. 7.7 0 K/Jy, HPBW = 3:2) and 2372 MHZ (gain approx. 6.3 0 K/Jy, HPBW = 2'). Observations were made at 1400 MHz in the frequency switching mode, and at 2372 MHz in the total power mode. Gaussians were fit to be observed lines to derive velocities, line widths, and line temperatures. From the velocities kinematic distances were derived. For eleven sources H I absorption measurements were also made. The absorption spectra enabled the kinematic distance ambiguity to be resolved for some sources. The absorption spectra themselves were found to have extremely sharp, non-gaussian edges. One explanation for these is a model where the interstellar medium contains many H I cloudlets with T/sub s/less than or equal to 100 0 K and turbulent velocities less than or equal to 3 km/s. The H I absorption spectrum is then a superposition of many narrow gaussian profiles. It was also found from a comparison of H I absorption velocities with radio recombination line velocities that peculiar motions exist in the interstellar medium with velocities of up to 10 km/s. Using the measured line temperatures and continuum temperatures, estimates were desired of emission measures, electron temperatures, and electron densities, using a non-LTE analysis. Non-LTE effects were important only for the hottest and densest H II regions. The non-LTE calculations were checked through a comparison derivation of electron temperatures using hydrogen beta lines

  19. Water vapor spectroscopy in the 815-nm wavelength region for Differential Absorption Lidar measurements

    Science.gov (United States)

    Ponsardin, Patrick; Browell, Edward V.

    1995-01-01

    The differential absorption lidar (DIAL) technique was first applied to the remote measurement of atmospheric water vapor profiles from airborne platforms in 1981. The successful interpretation of the lidar profiles relies strongly on an accurate knowledge of specific water vapor absorption line parameters: line strength, pressure broadening coefficient, pressure-induced shift coefficient and the respective temperature-dependence factors. NASA Langley Research Center has developed and is currently testing an autonomous airborne water vapor lidar system: LASE (Lidar Atmospheric Sensing Experiment). This DIAL system uses a Nd:YAG-pumped Ti:Sapphire laser seeded by a diode laser as a lidar transmitter. The tunable diode has been selected to operate in the 813-818 nm wavelength region. This 5-nm spectral interval offers a large distribution of strengths for temperature-insensitive water vapor absorption lines. In support of the LASE project, a series of spectroscopic measurements were conducted for the 16 absorption lines that have been identified for use in the LASE measurements. Prior to this work, the experimental data for this water vapor absorption band were limited - to our knowledge - to the line strengths and to the line positions.

  20. Infrared absorption studies of the annealing of irradiated diamonds

    International Nuclear Information System (INIS)

    Woods, G.S.

    1984-01-01

    Natural (types Ia and IIa) and synthetic (type Ib) diamonds have been irradiated with energetic electrons and neutrons and then heated at temperatures up to 1400 deg C. Attendant changes in the infrared absorption spectra, especially above the Raman frequency (1332 cm -1 ), have been monitored. The most prominent absorption to develop in the infrared region proper, on annealing both type Ia and type Ib specimens, whether electron- or neutron-irradiated is the H1a line at 1450 cm -1 . Measurements taken of neutron-irradiated type Ia specimens show that the strength of this line is specimen-dependent, and that it is a linear function of radiation dose. Isochronal annealing studies show that the onset of the line occurs during heating at 250 deg C for type Ia specimens and at 650 deg C for type Ib specimens. The absorption begins to weaken during heating at 1100 deg C, but it is very persistent, surviving an anneal of 4 hours at 1400 deg C, albeit with diminished intensity. Three other weaker lines at 1438, 1358 and 1355 cm -1 develop with the 1450 cm -1 line, but differ from it and from each other in subsequent annealing behaviour. Other lines were observed; these are reported and discussed. (author)

  1. Absorption-line detections of 105-106 K gas in spiral-rich groups of galaxies

    International Nuclear Information System (INIS)

    Stocke, John T.; Keeney, Brian A.; Danforth, Charles W.; Syphers, David; Yamamoto, H.; Shull, J. Michael; Green, James C.; Froning, Cynthia; Savage, Blair D.; Wakker, Bart; Kim, Tae-Sun; Ryan-Weber, Emma V.; Kacprzak, Glenn G.

    2014-01-01

    Using the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope, the COS Science Team has conducted a high signal-to-noise survey of 14 bright QSOs. In a previous paper, these far-UV spectra were used to discover 14 'warm' (T ≥ 10 5 K) absorbers using a combination of broad Lyα and broad O VI absorptions. A reanalysis of a few of this new class of absorbers using slightly relaxed fitting criteria finds as many as 20 warm absorbers could be present in this sample. A shallow, wide spectroscopic galaxy redshift survey has been conducted around these sight lines to investigate the warm absorber environment, which is found to be spiral-rich groups or cluster outskirts with radial velocity dispersions σ = 250-750 km s –1 . While 2σ evidence is presented favoring the hypothesis that these absorptions are associated with the galaxy groups and not with the individual, nearest galaxies, this evidence has considerable systematic uncertainties and is based on a small sample size so it is not entirely conclusive. If the associations are with galaxy groups, the observed frequency of warm absorbers (dN/dz = 3.5-5 per unit redshift) requires them to be very extended as an ensemble on the sky (∼1 Mpc in radius at high covering factor). Most likely these warm absorbers are interface gas clouds whose presence implies the existence of a hotter (T ∼ 10 6.5 K), diffuse, and probably very massive (>10 11 M ☉ ) intra-group medium which has yet to be detected directly.

  2. Determination of As(III) and As(V) by Flow Injection-Hydride Generation-Atomic Absorption Spectrometry via On-line Reduction of As(V) by KI

    DEFF Research Database (Denmark)

    Nielsen, Steffen; Hansen, Elo Harald

    1997-01-01

    A volume-based flow injection (FI) procedure is described for the determination and speciation of trace inorganic arsenic, As(III) and As(V), via hydride generation-atomic absorption spectrometry (HG-AAS) of As(III). The determination of total arsenic is obtained by on-line reduction of As(V) to As...

  3. Clustering analysis of line indices for LAMOST spectra with AstroStat

    Science.gov (United States)

    Chen, Shu-Xin; Sun, Wei-Min; Yan, Qi

    2018-06-01

    The application of data mining in astronomical surveys, such as the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) survey, provides an effective approach to automatically analyze a large amount of complex survey data. Unsupervised clustering could help astronomers find the associations and outliers in a big data set. In this paper, we employ the k-means method to perform clustering for the line index of LAMOST spectra with the powerful software AstroStat. Implementing the line index approach for analyzing astronomical spectra is an effective way to extract spectral features for low resolution spectra, which can represent the main spectral characteristics of stars. A total of 144 340 line indices for A type stars is analyzed through calculating their intra and inter distances between pairs of stars. For intra distance, we use the definition of Mahalanobis distance to explore the degree of clustering for each class, while for outlier detection, we define a local outlier factor for each spectrum. AstroStat furnishes a set of visualization tools for illustrating the analysis results. Checking the spectra detected as outliers, we find that most of them are problematic data and only a few correspond to rare astronomical objects. We show two examples of these outliers, a spectrum with abnormal continuumand a spectrum with emission lines. Our work demonstrates that line index clustering is a good method for examining data quality and identifying rare objects.

  4. EVALUATION OF QUALITY INDICATORS RELATED TO QUALITY BREAD WHEAT PROMISING LINES

    Directory of Open Access Journals (Sweden)

    Watson Munyanyi

    2014-01-01

    Full Text Available The bread waste is one of the important socio-economic's issues country now, the urgent need is feeling to improve the wheat quality. Therefore, using the methods of farming and breeding is necessary to improve the quality of this strategic product. As a result, tests of quality's traits in wheat promising lines in Isfahan climate took place. In this study, the choice 17 advanced lines of compare the performances,s experiments, an experiment was conducted for two consecutive cropping (2011-2012 at cultural experiment and research centre in Isfahan located in Kabutar Abad region. Randomized complete block designs with 3 replications were compared with Spring variety (for control. Traits including: 1000 grain weight, hectolitre weight, protein content, Zeleny sedimentation rate, bread volume, grain moisture content, grain hardness, water absorption, falling number, percentage of dry gluten, gluten index, sedimentation rates were SDS.The results of the combined analysis of variance qualitative characteristics,s for two consecutive cropping showed that treatments with compare together and control variety had significant influence in 1% probability.Correlation coefficients of two years showed that the compound test significant positive correlation within grain hardness index and protein content, wet gluten and dry deposition rates of SDS. Also, significant positive correlation with the percentage of protein content of dry gluten. In view of the high correlation with protein content of dry gluten (quantity. However, grain hardness and relatively high correlation with SDS sedimentation as an important measure of protein quality. Therefore, the test results of dry gluten grains can be tough to choose in order to improve the quality of wheat bread may be used.

  5. Absence or interruption of the supra-acetabular line: a subtle plain film indicator of hip pathology

    International Nuclear Information System (INIS)

    Major, N.M.; Helms, C.A.

    1996-01-01

    Objective. To show that absence or interruption of the supraacetabular line is a subtle plain film indicator of pathology in the acetabulum. Design. Nineteen hips from 17 patients with known disease processes involving the acetabulum as demonstrated by subsequent magnetic resonance imaging, bone scan or plain film follow-up were evaluated with antero-posterior (AP) plain films of the pelvis. Three additional cases were diagnosed prospectively using interruption of the supra-acetabular line as the criterion for inclusion. Fifty AP plain films of the pelvis in patients without hip pain were examined prospectively to determine normal imaging criteria. Results and conclusions. The normal supra-acetabular line measures 2-3 mm in thickness superiorly and is a thin sclerotic line in the medial aspect. In all 22 hips (with pathology) in this series, the line was interrupted or absent. Loss or interruption of the supra-acetabular line may thus be a subtle pain film indicator of a disease process involving the acetabulum. This plain film sign has not previously been reported. (orig.). With 8 figs., 1 tab

  6. Weak hard X-ray emission from broad absorption line quasars: evidence for intrinsic X-ray weakness

    International Nuclear Information System (INIS)

    Luo, B.; Brandt, W. N.; Scott, A. E.; Alexander, D. M.; Gandhi, P.; Stern, D.; Teng, S. H.; Arévalo, P.; Bauer, F. E.; Boggs, S. E.; Craig, W. W.; Christensen, F. E.; Comastri, A.; Farrah, D.; Hailey, C. J.; Harrison, F. A.; Koss, M.; Ogle, P.; Puccetti, S.; Saez, C.

    2014-01-01

    We report NuSTAR observations of a sample of six X-ray weak broad absorption line (BAL) quasars. These targets, at z = 0.148-1.223, are among the optically brightest and most luminous BAL quasars known at z < 1.3. However, their rest-frame ≈2 keV luminosities are 14 to >330 times weaker than expected for typical quasars. Our results from a pilot NuSTAR study of two low-redshift BAL quasars, a Chandra stacking analysis of a sample of high-redshift BAL quasars, and a NuSTAR spectral analysis of the local BAL quasar Mrk 231 have already suggested the existence of intrinsically X-ray weak BAL quasars, i.e., quasars not emitting X-rays at the level expected from their optical/UV emission. The aim of the current program is to extend the search for such extraordinary objects. Three of the six new targets are weakly detected by NuSTAR with ≲ 45 counts in the 3-24 keV band, and the other three are not detected. The hard X-ray (8-24 keV) weakness observed by NuSTAR requires Compton-thick absorption if these objects have nominal underlying X-ray emission. However, a soft stacked effective photon index (Γ eff ≈ 1.8) for this sample disfavors Compton-thick absorption in general. The uniform hard X-ray weakness observed by NuSTAR for this and the pilot samples selected with <10 keV weakness also suggests that the X-ray weakness is intrinsic in at least some of the targets. We conclude that the NuSTAR observations have likely discovered a significant population (≳ 33%) of intrinsically X-ray weak objects among the BAL quasars with significantly weak <10 keV emission. We suggest that intrinsically X-ray weak quasars might be preferentially observed as BAL quasars.

  7. Saturated two-photon absorption by atoms in a perturber gas

    International Nuclear Information System (INIS)

    Nienhuis, G.

    1980-01-01

    We derive a general expression for the two-photon absorption spectrum of a three-state atom excited by two mono-chromatic radiation fields. Collisional line-broadening effects are incorporated, and the result allows inclusion of profiles with a validity outside the impact limit. Results of previous work are recovered in the appropriate limits. Saturation affects the different lines in the two-photon absorption spectrum in a different fashion. (orig.)

  8. 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

  9. Development of an automated sequential injection on-line solvent extraction-back extraction procedure as demonstrated for the determination of cadmium with detection by electrothermal atomic absorption spectrometry

    DEFF Research Database (Denmark)

    Wang, Jianhua; Hansen, Elo Harald

    2002-01-01

    An automated sequential injection (SI) on-line solvent extraction-back extraction separation/preconcentration procedure is described. Demonstrated for the assay of cadmium by electrothermal atomic absorption spectrometry (ETAAS), the analyte is initially complexed with ammonium pyrrolidinedithioc......An automated sequential injection (SI) on-line solvent extraction-back extraction separation/preconcentration procedure is described. Demonstrated for the assay of cadmium by electrothermal atomic absorption spectrometry (ETAAS), the analyte is initially complexed with ammonium....../preconcentration process of the ensuing sample. An enrichment factor of 21.4, a detection limit of 2.7 ng/l, along with a sampling frequency of 13s/h were obtained at a sample flow rate of 6.0mlmin/sup -1/. The precision (R.S.D.) at the 0.4 mug/l level was 1.8% as compared to 3.2% when quantifying the organic extractant...

  10. Metastable argon atom density in complex argon/acetylene plasmas determined by means of optical absorption and emission spectroscopy

    International Nuclear Information System (INIS)

    Sushkov, Vladimir; Herrendorf, Ann-Pierra; Hippler, Rainer

    2016-01-01

    Optical emission and absorption spectroscopy has been utilized to investigate the instability of acetylene-containing dusty plasmas induced by growing nano-particles. The density of Ar(1s 5 ) metastable atoms was derived by two methods: tunable diode laser absorption spectroscopy and with the help of the branching ratio method of emitted spectral lines. Results of the two techniques agree well with each other. The density of Ar(1s 3 ) metastable atoms was also measured by means of optical emission spectroscopy. The observed growth instability leads to pronounced temporal variations of the metastable and other excited state densities. An analysis of optical line ratios provides evidence for a depletion of free electrons during the growth cycle but no indication for electron temperature variations. (paper)

  11. Infrared-laser spectroscopy using a long-pathlength absorption cell

    International Nuclear Information System (INIS)

    Kim, K.C.; Briesmeister, R.A.

    1983-01-01

    The absorption measurements in an ordinary cell may require typically a few torr pressure of sample gas. At these pressures the absorption lines are usually pressure-broadened and, therefore, closely spaced transitions are poorly resolved even at diode-laser resolution. This situation is greatly improved in Doppler-limited spectroscopy at extremely low sample pressures. Two very long-pathlength absorption cells were developed to be used in conjunction with diode lasers. They were designed to operate at controlled temperatures with the optical pathlength variable up to approx. 1.5 km. Not only very low sample pressures are used for studies with such cells but also the spectroscopic sensitivity is enhanced over conventional methods by a factor of 10 3 to 10 4 , improving the analytical capability of measuring particle densities to the order of 1 x 10'' molecules/cm 3 . This paper presents some analytical aspects of the diode laser spectroscopy using the long-pathlength absorption cells in the areas of absorption line widths, pressure broadening coefficients, isotope composition measurements and trace impurity analysis

  12. A New Analysis of Stark and Zeeman Effects on Hydrogen Lines in Magnetized DA White Dwarfs

    Directory of Open Access Journals (Sweden)

    Ny Kieu

    2017-11-01

    Full Text Available White dwarfs with magnetic field strengths larger than 10 T are understood to represent more than 10% of the total population of white dwarfs. The presence of such strong magnetic fields is clearly indicated by the Zeeman triplet structure visible on absorption lines. In this work, we discuss the line broadening mechanisms and focus on the sensitivity of hydrogen lines on the magnetic field. We perform new calculations in conditions relevant to magnetized DA stellar atmospheres using models inspired from magnetic fusion plasma spectroscopy. A white dwarf spectrum from the Sloan Digital Sky Survey (SDSS database is analyzed. An effective temperature is provided by an adjustment of the background radiation with a Planck function, and the magnetic field is inferred from absorption lines presenting a Zeeman triplet structure. An order-of-magnitude estimate for the electron density is also performed from Stark broadening analysis.

  13. High-resolution continuum source atomic absorption spectrometry for the simultaneous or sequential monitoring of multiple lines. A critical review of current possibilities

    International Nuclear Information System (INIS)

    Resano, M.; Flórez, M.R.; García-Ruiz, E.

    2013-01-01

    This work examines the capabilities and limitations of commercially available high-resolution continuum source atomic absorption spectrometry instrumentation for multi-line monitoring, discussing in detail the possible strategies to develop multi-element methodologies that are truly simultaneous, or else sequential, but from the same sample aliquot. Moreover, the simultaneous monitoring of various atomic or molecular lines may bring other important analytical advantages, such as: i) expansion of the linear range by monitoring multiplets; ii) improvements in the limit of detection and in precision by summing the signals from different lines of the same element or molecule; iii) simple correction for matrix-effects by selecting a suitable internal standard; or iv) accurate mathematical correction of spectral overlaps by simultaneous monitoring of free lines of the interfering molecule or element. This work discusses how authors have made use of these strategies to develop analytical methodologies that permit the straightforward analysis of complex samples. - Highlights: • HR CS AAS potential for simultaneous multi-line monitoring is critically examined. • Strategies to develop simultaneous multi-element methods are discussed. • Other benefits of multi-line monitoring (e.g., use of an IS or LSBC) are highlighted. • Selected examples from the literature are discussed in detail

  14. High-resolution continuum-source atomic absorption spectrometry: what can we expect?

    Directory of Open Access Journals (Sweden)

    Welz Bernhard

    2003-01-01

    Full Text Available A new instrumental concept has been developed for atomic absorption spectrometry (AAS, using a high-intensity xenon short-arc lamp as continuum radiation source, a high-resolution double-echelle monochromator and a CCD array detector, providing a resolution of ~2 pm per pixel. Among the major advantages of the system are: i an improved signal-to-noise ratio because of the high intensity of the radiation source, resulting in improved photometric precision and detection limits; ii for the same reason, there are no more 'weak' lines, i.e. secondary lines can be used without compromises; iii new elements might be determined, for which no radiation source has been available; iv the entire spectral environment around the analytical line becomes 'visible', giving a lot more information than current AAS instruments; v the CCD array detector allows a truly simultaneous background correction close to the analytical line; vi the software is capable of storing reference spectra, e.g. of a molecular absorption with rotational fine structure, and of subtracting such spectra from the spectra recorded for a sample, using a least squares algorithm; vii although not yet realized, the system makes possible a truly simultaneous multi-element AAS measurement when an appropriate two-dimensional detector is used, as is already common practice in optical emission spectrometry; vii preliminary experiments have indicated that the instrumental concept could result in a more rugged analytical performance in the determination of trace elements in complex matrices.

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

    Science.gov (United States)

    Chou, M. D.

    1980-01-01

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

  16. High-temperature measurements of methane and acetylene using quantum cascade laser absorption near 8μm

    KAUST Repository

    Sajid, M.B.

    2015-04-01

    The mid-infrared wavelength region near 8 mu m contains absorption bands of several molecules such as water vapor, hydrogen peroxide, nitrous oxide, methane and acetylene. A new laser absorption sensor based on the v(4) band of methane and the v(4)+v(5) band of acetylene is reported for interference-free, time-resolved measurements under combustion-relevant conditions. A detailed line-selection procedure was used to identify optimum transitions. Methane and acetylene were measured at the line centers of Q12 (1303.5 cm(-1)) and P23 (1275.5 cm(-1)) transitions, respectively. High-temperature absorption cross sections of methane and acetylene were measured at peaks (on-line) and valleys (off-line) of the selected absorption transitions. The differential absorption strategy was employed to eliminate interference absorption from large hydrocarbons. Experiments were performed behind reflected shock waves over a temperature range of 1200-2200 K, between pressures of 1-4 atm. The diagnostics were then applied to measure the respective species time-history profiles during the shock-heated pyrolysis of n-pentane. (C) 2015 Elsevier Ltd. All rights reserved.

  17. Absorption optical density as a diagnostic tool for indicating the ...

    African Journals Online (AJOL)

    Nanotechnology has recently emerged as a promising approach for treatment and diagnosis of a variety of diseases. The aim of this study was to evaluate the blood absorption spectra to assess bioaccumulation and toxic effects of 100 μl of 10 and 50 nm gold nanoparticles (GNPs) upon intraperitoneal administration in rats ...

  18. Sequential injection on-line matrix removal and trace metal preconcentration using a PTFE beads packed column as demonstrated for the determination of cadmium by electrothermal atomic absorption spectrometry

    DEFF Research Database (Denmark)

    Wang, Jianhua; Hansen, Elo Harald

    2002-01-01

    A sequential injection (SI) on-line matrix removal and trace metal preconcentration procedure by using a novel microcolumn packed with PTFE beads is described, and demonstrated for trace cadmium analysis with detection by electrothermal atomic absorption spectrometry (ETAAS). The analyte...

  19. A POPULATION OF WEAK METAL-LINE ABSORBERS SURROUNDING THE MILKY WAY

    International Nuclear Information System (INIS)

    Richter, Philipp; Charlton, Jane C.; Fangano, Alessio P. M.; Bekhti, Nadya Ben; Masiero, Joseph R.

    2009-01-01

    We report on the detection of a population of weak metal-line absorbers in the halo or nearby intergalactic environment of the Milky Way. Using high-resolution ultraviolet absorption-line spectra of bright quasars (QSO) obtained with the Space Telescope Imaging Spectrograph (STIS), along six sight lines we have observed unsaturated, narrow absorption in O I and Si II, together with mildly saturated C II absorption at high radial velocities (|v LSR | = 100-320 km s -1 ). The measured O I column densities lie in the range N(O I) 14 cm -2 implying that these structures represent Lyman limit Systems and sub-Lyman limit System with H I column densities between 10 16 and 3 x 10 18 cm -2 , thus below the detection limits of current 21 cm all-sky surveys of high-velocity clouds (HVCs). The absorbers apparently are not directly associated with any of the large high column density HVC complexes, but rather represent isolated, partly neutral gas clumps embedded in a more tenuous, ionized gaseous medium situated in the halo or nearby intergalactic environment of the Galaxy. Photoionization modeling of the observed low ion ratios suggests typical hydrogen volume densities of n H > 0.02 cm -3 and characteristic thicknesses of a several parsec down to subparsec scales. For three absorbers, metallicities are constrained in the range of 0.1-1.0 solar, implying that these gaseous structures may have multiple origins inside and outside the Milky Way. Using supplementary optical absorption-line data, we find for two other absorbers Ca II/O I column-density ratios that correspond to solar Ca/O abundance ratios. This finding indicates that these clouds do not contain significant amounts of dust. This population of low column density gas clumps in the circumgalactic environment of the Milky Way is indicative of the various processes that contribute to the circulation of neutral gas in the extended halos of spiral galaxies. These processes include the accretion of gas from the

  20. Retrival experience as an accurate indicator of person identification in line-ups

    Directory of Open Access Journals (Sweden)

    María José Contreras

    2011-07-01

    Full Text Available Responses in eyewitness identification of a person in a line-up may be based on two types of recovery experiences, remember and know experiences. Remember responses involve eyewitness identification of the target person as an episodic memory task, because it implies retrieving information about the target person in the place and at the time of the event. Know responses, in contrast, engage recognition based on familiarity or perceptual facilitation, that is, as a semantic memory task. To explore the relation between retrieval experiences and recognition accuracy, 86 participants took part in a recognition task with two conditions: one with an interpolated target absent line-up and the other only with the target present line-up. Accuracy of recognition and retrieval experience was measured. The results showed that, having previously participated in a target-absent line-up, increased omissions, while the number of hits decreased. Furthermore, participants’ know responses were associated to false recognition, whilst remember responses were associated to hits in recognition. Thus, asking eyewitnesses to inform about the kind of retrieval experience in which they based their recognition responses, may serve as a reliable indicator of accuracy in recognition. Future studies are needed to investigate whether this is also the case in natural settings.

  1. Specific features of the temperature dependence of the exciton absorption integral in CdS crystals

    International Nuclear Information System (INIS)

    Novikov, A.B.; Solov'ev, L.E.; Talalaev, V.G.

    1986-01-01

    Cadmium sulfide crystals 0.4-2 μm thick in the 4.2-120 K temperature range are investigated experimentally. The shape of the first exciton absorption line in CdS and dependence of integral exciton absorption factor (IEAF) on the quenching constant j are calculated. Rapid growth of the absorption factor in the maximum of the absorption line and decrease of halfwidth of the factor are shown to take place with j increase. The calculation has disclosed that the Bouguer law is observed excluding negligible IEAF oscillations at variation of crystal thickness. Non-monotonous temperature dependence of IEAF is disclosed in some investigated samples; it, obviously, testifies to non-monotonous temperature dependence of j. Depolarization of the absorption line of high-energy exciton states with n=2 and n=3 is discovered in some samples for the first time

  2. WATER ABSORPTION FROM GAS VERY NEAR THE MASSIVE PROTOSTAR AFGL 2136 IRS 1

    International Nuclear Information System (INIS)

    Indriolo, Nick; Neufeld, D. A.; Seifahrt, A.; Richter, M. J.

    2013-01-01

    We present ground-based observations of the ν 1 and ν 3 fundamental bands of H 2 O toward the massive protostar AFGL 2136 IRS 1, identifying absorption features due to 47 different ro-vibrational transitions between 2.468 μm and 2.561 μm. Analysis of these features indicates the absorption arises in warm (T = 506 ± 25 K), very dense (n(H 2 ) > 5 × 10 9 cm –3 ) gas, suggesting an origin close to the central protostar. The total column density of warm water is estimated to be N(H 2 O) = (1.02 ± 0.02) × 10 19 cm –2 , giving a relative abundance of N(H 2 O)/N(H 2 ) ≈ 10 –4 . Our study represents the first extensive use of water vapor absorption lines in the near infrared, and demonstrates the utility of such observations in deriving physical parameters

  3. Bismuth as a general internal standard for lead in atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Bechlin, Marcos A.; Fortunato, Felipe M.; Ferreira, Edilene C.; Neto, José A. Gomes; Nóbrega, Joaquim A.; Donati, George L.; Jones, Bradley T.

    2014-01-01

    Highlights: • Single internal standard is commonly proposed for definite application in AAS. • Internal standard for general use in AAS techniques is original. • Bi showed efficiency as internal standard for Pb determinations by FAAS and GFAAS. • Assorted samples were analyzed and accurate results were found. - Abstract: Bismuth was evaluated as internal standard for Pb determination by line source flame atomic absorption spectrometry (LS FAAS), high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS) and line source graphite furnace atomic absorption spectrometry (LS GFAAS). Analysis of samples containing different matrices indicated close relationship between Pb and Bi absorbances. Correlation coefficients of calibration curves built up by plotting A Pb /A Bi versus Pb concentration were higher than 0.9953 (FAAS) and higher than 0.9993 (GFAAS). Recoveries of Pb improved from 52–118% (without IS) to 97–109% (IS, LS FAAS); 74–231% (without IS) to 96–109% (IS, HR-CS FAAS); and 36–125% (without IS) to 96–110% (IS, LS GFAAS). The relative standard deviations (n = 12) were reduced from 0.6–9.2% (without IS) to 0.3–4.3% (IS, LS FAAS); 0.7–7.7% (without IS) to 0.1–4.0% (IS, HR-CS FAAS); and 2.1–13% (without IS) to 0.4–5.9% (IS, LS GFAAS)

  4. 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.

  5. The End of the Lines for OX 169: No Binary Broad-Line Region

    Science.gov (United States)

    Halpern, J. P.; Eracleous, M.

    2000-03-01

    We show that unusual Balmer emission-line profiles of the quasar OX 169, frequently described as either self-absorbed or double peaked, are actually neither. The effect is an illusion resulting from two coincidences. First, the forbidden lines are quite strong and broad. Consequently, the [N II] λ6583 line and the associated narrow-line component of Hα present the appearance of twin Hα peaks. Second, the redshift of 0.2110 brings Hβ into coincidence with Na I D at zero redshift, and ISM absorption in Na I D divides the Hβ emission line. In spectra obtained over the past decade, we see no substantial change in the character of the line profiles and no indication of intrinsic double-peaked structure. The Hγ, Mg II, and Lyα emission lines are single peaked, and all of the emission-line redshifts are consistent once they are correctly attributed to their permitted and forbidden-line identifications. A systematic shift of up to 700 km s-1 between broad and narrow lines is seen, but such differences are common and could be due to gravitational and transverse redshift in a low-inclination disk. Stockton & Farnham had called attention to an apparent tidal tail in the host galaxy of OX 169 and speculated that a recent merger had supplied the nucleus with a coalescing pair of black holes that was now revealing its existence in the form of two physically distinct broad-line regions. Although there is no longer any evidence for two broad emission-line regions in OX 169, binary black holes should form frequently in galaxy mergers, and it is still worthwhile to monitor the radial velocities of emission lines that could supply evidence of their existence in certain objects.

  6. Determination of rare earth element content in yttrium aluminium garnet crystals by absorption spectrophotometry method

    International Nuclear Information System (INIS)

    Mejl'man, M.L.; Kolomijtsev, A.I.; Baskakova, Z.M.; Bagdasarov, Kh.S.; Kevorkov, A.M.

    1985-01-01

    Possibility of determination of relative and absolute contents of impurity trivalent REE ions in yttrium aluminium garnet of (YAG) monocrystals has been studied by the absorption spectrophotometry method. Absorption spectra in UV and visible regions YAG monocrystals doped by REE are studied. For each admixture the characteristic lines or absorption bands not overlapping with lines of other admixtures are defined and investigated. The extinction coefficients of characteristic lines are determined which allow one to measure absolute REE admixture concentrations in garnet crystals. A conclusion is drawn that the absorption spectrophotometry method permits to measure REE admixture content in YAG monocrystals within the concentration range of approximately 1x10sup(-3)-5 mas. % with an accuracy not less than 20% (with sample thickness of approximately 1 cm)

  7. Durability Indicators in High Absorption Recycled Aggregate Concrete

    Directory of Open Access Journals (Sweden)

    Luis F. Jiménez

    2015-01-01

    Full Text Available The use of recycled aggregates in structural concrete production has the inconvenience of increasing the fluid transport properties, such as porosity, sorptivity, and permeability, which reduces the resistance against penetration of environmental loads such as carbon dioxide and chloride ion. In this paper, behavior of ten concrete mixtures with different percentages of coarse aggregate replacement was studied. The recycled material was recovered by crushing of concrete rubble and had high absorption values. The results showed that it is possible to achieve good resistance to carbonation and chloride penetration with up to 50% replacement of recycled coarse aggregate for 0.5 water/cement ratio. Finally, new indexes for porosity and sorptivity were proposed to assess the quality of concrete.

  8. Can double-peaked lines indicate merging effects in AGNs?

    Directory of Open Access Journals (Sweden)

    Popović L.Č.

    2000-01-01

    Full Text Available The influence of merging effects in the central part of an Active Galactic Nucleus (AGN on the emission spectral line shapes are discussed. We present a model of close binary Broad Line Region. The numerical experiments show that the merging effects can explain double peaked lines. The merging effects may also be present in the center of AGNs, although they emit slightly asymmetric as well as symmetric and relatively stable (in profile shape spectral lines. Depending on the black hole masses and their orbit elements such model may explain some of the line profile shapes observed in AGNs. This work shows that if one is looking for the merging effects in the central region as well as in the wide field structure of AGNs, he should first pay attention to objects which have double peaked lines.

  9. VizieR Online Data Catalog: Quasars narrow absorption lines from SDSS (Chen+, 2015)

    Science.gov (United States)

    Chen, Z.-F.; Gu, Q.-S.; Chen, Y.-M.; Cao, Y.

    2017-11-01

    The Baryon Oscillation Spectroscopic Survey (BOSS: Eisenstein et al. 2011AJ....142...72E; Paris et al. 2012, Cat. VII/269) is the main dark-time legacy survey of the third stage of the SDSS, which used the same 2.5-m telescope (Gunn et al. 2006AJ....131.2332G; Ross et al. 2012, J/ApJS/199/3) as the first and second stages of the SDSS (hereafter SDSS-I/II). SDSS-I/II spectra have a wavelength coverage from 3800-9200Å with a spectral resolution of 1800-2200 (e.g. York et al. 2000AJ....120.1579Y). BOSS spectra span a range from 3600-10500Å at a resolution of 1300-2500 (Paris et al. 2012, Cat. VII/269). During the first two years, BOSS detected 87822 quasars over an area of 3275 deg2, including 7932 quasars that were observed by SDSS-I/II as well. Quasars observed by both SDSS-I/II and BOSS provide a remarkable chance to study the variabilities of absorption lines in a large population. Throughout this work, we take the quasar emission redshifts provided by Hewett & Wild (2010, J/MNRAS/405/2302, http://das.sdss.org/va/HewettWilddr7qso_newz/) directly. (2 data files).

  10. 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

  11. Mass loss and asymmetries in the lines of Iota Coronae Borealis

    International Nuclear Information System (INIS)

    Kapp, A.H.

    1976-01-01

    Recent observations by Smith and Parsons of the Hg--Mn star iota CrB have revealed slight asymmetries in the absorption lines. While these asymmetries are near the limits of detection at the resolution used, their appearance in several lines indicates that they are real. Proposed explanations of this phenomenon are not completely satisfactory. In this Letter it will be shown that the asymmetries are consistent with an accelerating radial flow of material in the photosphere of this star. The velocity needed to reproduce the observed asymmetry corresponds to a mass loss rate of roughly 10 -7 M/sub solar mass/ yr -1

  12. Evidence for Ultra-Fast Outflows in Radio-Quiet AGNs. 2; Detailed Photoionization Modeling of Fe K-Shell Absorption Lines

    Science.gov (United States)

    Tombesi, Francesco; Clapp, M.; Reeves, J. N.; Palumbo, G. G. C.; Braito, V.; Dadina, M.

    2011-01-01

    X-ray absorption line spectroscopy has recently shown evidence for previously unknown Ultra-fast Outflows (UFOs) in radio-quiet AGNs. In the previous paper of this series we defined UFOs as those absorbers with an outflow velocity higher than 10,000km/s and assessed the statistical significance of the associated blue shifted FeK absorption lines in a large sample of 42 local radio-quiet AGNs observed with XMM-Newton. In the present paper we report a detailed curve of growth analysis and directly model the FeK absorbers with the Xstar photo-ionization code. We confirm that the frequency of sources in the radio-quiet sample showing UFOs is >35%. The outflow velocity distribution spans from \\sim10,000km/s (\\sim0.03c) up to \\siml00,000kmis (\\sim0.3c), with a peak and mean value of\\sim42,000km/s (\\sim0.14c). The ionization parameter is very high and in the range log\\xi 3-6 erg s/cm, with a mean value of log\\xi 4.2 erg s/cm. The associated column densities are also large, in the range N_H\\siml0(exp 22)-10(exp 24)/sq cm, with a mean value of N_H\\siml0(exp23)/sq cm. We discuss and estimate how selection effects, such as those related to the limited instrumental sensitivity at energies above 7keV, 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 provide important clues on the connection between accretion disks, winds and jets.

  13. X-Ray K Absorption Edge Structures of Ligand Chlorine Ion in Some Cobalt Coordination Compounds

    Science.gov (United States)

    Obashi, Masayoshi; Matsukawa, Tokuo

    1983-03-01

    The X-ray Cl K absorption spectra in [Co(NH3)6]Cl3, [Co(NH3)5Cl]Cl2, trans-[Co(NH3)4Cl2]Cl and Cs2[CoCl4] are measured with a high-resolution vacuum two-crystal spectrometer. The spectra, except that of [Co(NH3)6]Cl3, show an extremely narrow absorption line at the absorption threshold. The result is interpreted on the basis of molecular orbital theory and it is proposed that the intensity of these narrow absorption lines depends on the chemical state between the cobalt and ligand chlorine ions. The narrow absorption line may well be attributed to transitions of the Cl 1s electron into the eg* antibonding orbitals having partially the 3p character of chlorine in [Co(NH3)5Cl]Cl2 and trans-[Co(NH3)4Cl2]Cl. In Cs2[CoCl4] it may be ascribed to the Cl 1s-t2* transitions.

  14. Threshold nonlinear absorption in Zeeman transitions

    International Nuclear Information System (INIS)

    Narayanan, Andal; Hazra, Abheera; Sandhya, S N

    2010-01-01

    We experimentally study the absorption spectroscopy from a collection of gaseous 87 Rb atoms at room temperature irradiated with three fields. Two of these fields are in a pump-probe saturation absorption configuration. The third field co-propagates with the pump field. The three fields address Zeeman degenerate transitions between hyperfine levels 5S 1/2 , F = 1 and 5P 3/2 , F = 0, F = 1 around the D2 line. We find a sub-natural absorption resonance in the counter-propagating probe field for equal detunings of all three fields. This absorption arises in conjunction with the appearance of increased transmission due to electro-magnetically induced transparency in the co-propagating fields. The novel feature of this absorption is its onset only for the blue of 5P 3/2 , F = 0, as the laser frequency is scanned through the excited states 5P 3/2 , F = 0, F = 1 and F = 2. The absorption rapidly rises to near maximum values within a narrow band of frequency near 5P 3/2 , F = 0. Our experimental results are compared with a dressed atom model. We find the threshold absorption to be a result of coherent interaction between the dressed states of our system.

  15. Luminescence in Primordial Helium Lines at the Pre-recombination Epoch

    Science.gov (United States)

    Dubrovich, V. K.; Grachev, S. I.

    2018-04-01

    The formation of luminescent subordinate He I lines by the absorption of radiation from a source in lines of the main He I series in an expanding Universe is considered. A burst of radiation in continuum is assumed to occur at some instant of time corresponding to redshift z 0. This radiation is partially absorbed at different z < z 0 in lines of the main He I series (different pumping channels) and then is partially converted into radiation in subordinate lines. If ν ik is the laboratory transition frequency of some subordinate line emerging at some z, then at the present epoch its frequency will be ν = ν ik /(1 + z). The quantum yield, i.e., the number of photons emitted in the subordinate line per initial excited atom, has been calculated for different z (and, consequently, for different ν). Several pumping channels have been considered. We show that the luminescent lines can be both emission and absorption ones; the same line can be an emission one for one of the pumping channels and an absorption one for another. For example, the 1s2s-1s2p (1S-1P*) line is an emission one for the 1s2-1s2p pumping and an absorption one for the 1s2-1s3p pumping. We show that in the frequency range 30-80 GHz the total quantum yield for the first and second of the above channels can reach +50 and -50%, respectively.

  16. High-temperature measurements of methane and acetylene using quantum cascade laser absorption near 8 μm

    International Nuclear Information System (INIS)

    Sajid, M.B.; Javed, T.; Farooq, A.

    2015-01-01

    The mid-infrared wavelength region near 8 μm contains absorption bands of several molecules such as water vapor, hydrogen peroxide, nitrous oxide, methane and acetylene. A new laser absorption sensor based on the ν 4 band of methane and the ν 4 +ν 5 band of acetylene is reported for interference-free, time-resolved measurements under combustion-relevant conditions. A detailed line-selection procedure was used to identify optimum transitions. Methane and acetylene were measured at the line centers of Q12 (1303.5 cm −1 ) and P23 (1275.5 cm −1 ) transitions, respectively. High-temperature absorption cross sections of methane and acetylene were measured at peaks (on-line) and valleys (off-line) of the selected absorption transitions. The differential absorption strategy was employed to eliminate interference absorption from large hydrocarbons. Experiments were performed behind reflected shock waves over a temperature range of 1200–2200 K, between pressures of 1–4 atm. The diagnostics were then applied to measure the respective species time-history profiles during the shock-heated pyrolysis of n-pentane. - Highlights: • Methane measured at the peak of Q(12) transition in the ν 4 band. • Acetylene measured at the peak of P(23) transition in the ν 4 +ν 5 band. • Differential absorption strategy employed to eliminate broadband interference absorption. • Absorption cross-sections measured over 1200–2200 K and 1–4 atm. • Methane and acetylene time-histories measured during the pyrolysis of n-pentane

  17. Size of the z = 0.437 H I absorption region toward the QSO 3C 196

    International Nuclear Information System (INIS)

    Brown, R.L.; Benson, J.M.; Broderick, J.J.; Johnston, K.J.; Mitchell, K.J.

    1988-01-01

    VLBI spectral line observations made at the frequency of the z = 0.437 H I absorption line toward the extended radio QSO 3C 196 demonstrate that the absorption does not occur against the more compact continuum structure in this object. Apparently the H I absorption line results from absorption of the lower brightness continuum emission by an intervening cloud with an angular diameter which must be greater than 0.63 arcsec. For a standard cosmology, this corresponds to a linear extent greater than 2.25 kpc. For a spherical cloud, the mass of absorbing gas is near 7 x 10 to the 7th solar masses. Thus this particular QSO absorbing cloud is surprisingly large and massive. 22 references

  18. Calcium absorption and achlorhydria

    International Nuclear Information System (INIS)

    Recker, R.R.

    1985-01-01

    Defective absorption of calcium has been thought to exist in patients with achlorhydria. The author compared absorption of calcium in its carbonate form with that in a pH-adjusted citrate form in a group of 11 fasting patients with achlorhydria and in 9 fasting normal subjects. Fractional calcium absorption was measured by a modified double-isotope procedure with 0.25 g of calcium used as the carrier. Mean calcium absorption (+/- S.D.) in the patients with achlorhydria was 0.452 +/- 0.125 for citrate and 0.042 +/- 0.021 for carbonate (P less than 0.0001). Fractional calcium absorption in the normal subjects was 0.243 +/- 0.049 for citrate and 0.225 +/- 0.108 for carbonate (not significant). Absorption of calcium from carbonate in patients with achlorhydria was significantly lower than in the normal subjects and was lower than absorption from citrate in either group; absorption from citrate in those with achlorhydria was significantly higher than in the normal subjects, as well as higher than absorption from carbonate in either group. Administration of calcium carbonate as part of a normal breakfast resulted in completely normal absorption in the achlorhydric subjects. These results indicate that calcium absorption from carbonate is impaired in achlorhydria under fasting conditions. Since achlorhydria is common in older persons, calcium carbonate may not be the ideal dietary supplement

  19. Weak Hard X-Ray Emission from Broad Absorption Line Quasars: Evidence for Intrinsic X-Ray Weakness

    DEFF Research Database (Denmark)

    Luo, B.; Brandt, W. N.; Alexander, D. M.

    2014-01-01

    We report NuSTAR observations of a sample of six X-ray weak broad absorption line (BAL) quasars. These targets, at z = 0.148-1.223, are among the optically brightest and most luminous BAL quasars known at z 330 times weaker than...... expected for typical quasars. Our results from a pilot NuSTAR study of two low-redshift BAL quasars, a Chandra stacking analysis of a sample of high-redshift BAL quasars, and a NuSTAR spectral analysis of the local BAL quasar Mrk 231 have already suggested the existence of intrinsically X-ray weak BAL...... quasars, i.e., quasars not emitting X-rays at the level expected from their optical/UV emission. The aim of the current program is to extend the search for such extraordinary objects. Three of the six new targets are weakly detected by NuSTAR with ≲ 45 counts in the 3-24 keV band, and the other three...

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

    International Nuclear Information System (INIS)

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

    1989-01-01

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

  1. Anomalous non-resonant microwave absorption in SmFeAs(O,F) polycrystalline sample

    Energy Technology Data Exchange (ETDEWEB)

    Onyancha, R.B., E-mail: 08muma@gmail.com [Department of Physics, College of Science, Engineering and Technology, University of South Africa, Johannesburg, 1710 (South Africa); Shimoyama, J. [Department of Applied Chemistry, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo (Japan); Singh, S.J. [Leibniz-Institute for Solid State and Materials Research, IFW-Dresden, D-01171 Dresden (Germany); Hayashi, K.; Ogino, H. [Department of Applied Chemistry, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo (Japan); Srinivasu, V.V. [Department of Physics, College of Science, Engineering and Technology, University of South Africa, Johannesburg, 1710 (South Africa)

    2017-02-15

    Highlights: • The non-resonant microwave absorption (NRMA) line shape in evolved with microwave power. • Observed a cross over from ‘normal’ absorption to ‘anomalous’ absorption as a function of microwave power. • The anomalous absorption has been explained in the context of non-hysteretic Josephson junction. - Abstract: Here we present the non-resonant microwave absorption (NRMA) studies on SmFeAsO{sub 0.88}F{sub 0.12} polycrystalline sample measured at 6.06 K with the magnetic field swept from −250 G to +250 G at a frequency of 9.45 GHz. It was observed that the (NRMA) line shape evolves as a function of microwave power. Again, the signal intensity increases from 22.83 µW to 0.710 mW where it reaches a maximum and quite remarkably it changed from ‘normal’ absorption to ‘anomalous’ absorption at 2.247 mW, then the intensity decreases with further increase of microwave power. The crossover from ‘normal’ to ‘anomalous’ NRMA absorption and its dependence on microwave power is a new phenomenon in iron pnictides superconductors and we have attributed this anomaly to come from non-hysteretic Josephson junction.

  2. CO2 CAPTURE BY ABSORPTION WITH POTASSIUM CARBONATE

    Energy Technology Data Exchange (ETDEWEB)

    Gary T. Rochelle; Eric Chen; Jennifer Lu; Babatunde Oyenekan; Ross Dugas

    2005-04-29

    The objective of this work is to improve the process for CO{sub 2} capture by alkanolamine absorption/stripping by developing an alternative solvent, aqueous K{sub 2}CO{sub 3} promoted by piperazine. Stripper modeling suggests the energy requirement with a simple stripper will be about the same for 5 m K{sup +}/2.5 m PZ and 7 m MEA. Modeling with a generic solvent shows that the optimum heat of CO{sub 2} desorption to minimize heat duty lies between 15 and 25 kcal/gmol. On-line pH and density measurements are effective indicators of loading and total alkalinity for the K+/PZ solvent. The baseline pilot plant campaign with 30% MEA has been started.

  3. Lactulose stimulates calcium absorption in postmenopausal women

    NARCIS (Netherlands)

    Heuvel, E.G.H.M. van den; Muijs, T.; Dokkum, W. van; Schaafsma, G.

    1999-01-01

    Animal studies have indicated that calcium absorption is increased by lactulose, a synthetic disaccharide. Therefore, the influence of lactulose on calcium absorption was measured in postmenopausal women who may benefit from the possible enhancing effect of lactulose on calcium absorption. Twelve

  4. Experimental studies of a zeeman-tuned xenon laser differential absorption apparatus.

    Science.gov (United States)

    Linford, G J

    1973-06-01

    A Zeeman-tuned cw xenon laser differential absorption device is described. The xenon laser was tuned by axial magnetic fields up to 5500 G generated by an unusually large water-cooled dc solenoid. Xenon laser lines at 3.37 micro, 3.51 micro, and 3.99 micro were tuned over ranges of 6 A, 6 A, and 11 A, respectively. To date, this apparatus has been used principally to study the details of formaldehyde absorption lines lying near the 3 .508-micro xenon laser transition. These experiments revealed that the observed absorption spectrum of formaldehyde exhibits a sufficiently unique spectral structure that the present technique may readily be used to measure relative concentrations of formaldehyde in samples of polluted air.

  5. Studies of the $\\beta$-decay of Sr nuclei on and near the N=Z Line with a Total Absorption Gamma-ray Spectrometer

    CERN Multimedia

    Marechal, F; Caballero ontanaya, L

    2002-01-01

    In the framework of the investigation of the shapes of the ground states of the parent nucleus, we propose to carry out measurements of the complete Gamow-Teller strength distribution for the $^{76-80}$Sr isotopes, with a new Total Absorption Gamma Spectrometer installed on a new beam line. The results will be compared with theoretical calculations based on the mean field approach. A brief report on the IS370 experiment on $^{72-75}$Kr decay, which was recently performed at ISOLDE, will be given and the performance of the sum spectrometer will be presented.

  6. Spectrophotometry of emission-line stars in the magellanic clouds

    Science.gov (United States)

    Bohannan, Bruce

    1990-01-01

    The strong emission lines in the most luminous stars in the Magellanic Clouds indicate that these stars have such strong stellar winds that their photospheres are so masked that optical absorption lines do not provide an accurate measure of photospheric conditions. In the research funded by this grant, temperatures and gravities of emission-line stars both in the Large (LMC) and Small Magellanic Clouds (SMC) have been measured by fitting of continuum ultraviolet-optical fluxes observed with IUE with theoretical model atmospheres. Preliminary results from this work formed a major part of an invited review 'The Distribution of Types of Luminous Blue Variables'. Interpretation of the IUE observations obtained in this grant and archive data were also included in a talk at the First Boulder-Munich Hot Stars Workshop. Final results of these studies are now being completed for publication in refereed journals.

  7. Luminescence and optical absorption determination in porous silicon

    International Nuclear Information System (INIS)

    Nogal, U.; Calderon, A.; Marin, E.; Rojas T, J. B.; Juarez, A. G.

    2012-10-01

    We applied the photoacoustic spectroscopy technique in order to obtain the optical absorption spectrum in porous silicon samples prepared by electrochemical anodic etching on n-type, phosphorous doped, (100)-oriented crystal-line silicon wafer with thickness of 300 μm and 1-5 ωcm resistivity. The porous layers were prepared with etching times of 13, 20, 30, 40 and 60 minutes. Also, we realized a comparison among the optical absorption spectrum with the photoluminescence and photo reflectance ones, both obtained at room temperature. Our results show that the absorption spectrum of the samples of porous silicon depends notably of the etching time an it consist of two distinguishable absorption bands, one in the Vis region and the other one in the UV region. (Author)

  8. PIXE analysis of U and Pu from hot particles: K-lines vs L-lines

    DEFF Research Database (Denmark)

    Jiménez-Ramos, M.C.; García López, J.; Eriksson, M.

    2012-01-01

    . (2007) [1] and Jiménez-Ramos et al. (2010) [2], radioactive particles from aircraft accidents in Palomares and Thule have been characterized. Using micro-Proton Induced X-ray Emission (μ-PIXE) and confocal X-ray fluorescence microprobe (μ-XRF), the L-lines of the main components in these particles, U......-lines present not overlapping between the main peaks in the spectra and the X-ray absorption in the sample is much lower than for L-lines....

  9. Something new: a new approach to correcting theoretical emitted intensities for absorption effects

    International Nuclear Information System (INIS)

    Willis, J.P.; Lachance, G.R.

    2002-01-01

    Full text: For monochromatic incident radiation of wavelength λ, absorption only (no enhancement), and ignoring such effects as the absorption edge jump ratio, the fluorescence yield, and the probability that a Kα line will be emitted instead of a Kβ line, a simplified view of the theoretical emitted intensity of a characteristic line of element >i= from a layer in a specimen is given by a familiar equation which involves mass absorption coefficients. While this equation allows for the calculation of the theoretical emitted intensity, it is cumbersome to use when trying to explain X-ray excitation in a step-wise manner. It is therefore proposed that the mass attenuation coefficients (μ iλ , and the sum of μ sλ ' + μ sλi '' , in the numerator and denominator of this equation be replaced by the product of two coefficients correcting for absorption, namely aN H aO. The advantages of using the proposed equation in the stepwise calculation of theoretical intensities (in a similar manner to Monte Carlo calculations) will be discussed. Copyright (2002) Australian X-ray Analytical Association Inc

  10. Temperature sensitivity of differential absorption lidar measurements of water vapor in the 720-nm region

    Science.gov (United States)

    Browell, Edward V.; Ismail, Syed; Grossmann, Benoist E.

    1991-01-01

    Recently measured properties of water vapor (H2O) absorption lines have been used in calculations to evalute the temperature sensitivity of differential absorption lidar (Dial) H2O measurements. This paper estimates the temperature sensitivity of H2O lines in the 717-733-nm region for both H2O mixing ratio and number density measurements, and discusses the influence of the H2O line ground state energies E-double-prime, the H2O absorption linewidths, the linewidth temperature dependence parameter, and the atmospheric temperature and pressure variations with altitude and location on the temperature sensitivity calculations. Line parameters and temperature sensitivity calculations for 67 H2O lines in the 720-nm band are given which can be directly used in field experiments. Water vapor lines with E-double-prime values in the 100-300/cm range were found to be optimum for Dial measurements of H2O number densities, while E-double-prime values in the 250-500/cm range were found to be optimum for H2O mixing ratio measurements.

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

    Science.gov (United States)

    Pihlström; Vermeulen; Taylor; Conway

    1999-11-01

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

  12. 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

    2018-06-01

    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.

  13. Holo-transcobalamin is an indicator of vitamin B-12 absorption in healthy adults with adequate vitamin B-12 status

    DEFF Research Database (Denmark)

    von Castel-Roberts, Kristina M; Mørkbak, Anne Louise; Nexo, Ebba

    2007-01-01

    BACKGROUND: It has been hypothesized that the response of holo-transcobalamin (holo-TC) to oral vitamin B-12 may be used to assess absorption. To develop a reliable clinical absorption test that uses holo-TC, it is necessary to determine the optimal timeline for vitamin B-12 administration...... and postdose assessment. OBJECTIVE: The objective of this study was to assess the magnitude and patterns of change in the postabsorption response of holo-TC to oral vitamin B-12. DESIGN: Adult (18-49 y) male and female participants (n = 21) with normal vitamin B-12 status were given three 9-mug doses...... of vitamin B-12 at 6-h intervals beginning early morning (baseline) on day 1. Blood was drawn at 17 timed intervals over the course of 3 d for the analysis of holo-TC and other indicators of vitamin B-12 status. RESULTS: Mean holo-TC increased significantly (P

  14. 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.

  15. 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...

  16. Comparison of optical properties of chromophoric dissolved organic matter (CDOM) in alpine lakes above or below the tree line: insights into sources of CDOM.

    Science.gov (United States)

    Su, Yaling; Chen, Feizhou; Liu, Zhengwen

    2015-05-01

    Here we investigated absorption and fluorescence properties of chromophoric dissolved organic matter (CDOM) in 15 alpine lakes located below or above the tree line to determine its source and composition. The results indicate that the concentrations of CDOM in below-tree-line lakes are significantly higher than in above-tree-line lakes, as evidenced from the absorption coefficients of a250 and a365. The intensities of the protein-like and humic-like fluorescence in below-tree-line lakes are higher than in above-tree-line lakes as well. Three fluorescent components were identified using parallel factor analysis (PARAFAC) modelling. Component 1 is probably associated with biological degradation of terrestrial humic component. The terrestrial humic-like component 2 is only found in below-tree-line lakes. The protein-like or phenolic component 3 is dominant in above-tree-line lakes, which is probably more derived from autochthonous origin. In this study, (1) higher a250/a365 and S275-295 values indicate smaller molecular weights of CDOM in above-tree-line lakes than in below-tree-line lakes, and smaller molecular weights at the surface than at 2.0 m depth; (2) SUVA254 and FI255 results provide evidence of lower percent aromaticity of CDOM in above-tree-line lakes; and (3) FI310 and FI370 suggest a strong allochthonous origin at the surface in below-tree-line lakes, and more contribution from autochthonous biological and aquatic bacterial origin in above-tree-line lakes.

  17. The development of an on-line gold analyser

    International Nuclear Information System (INIS)

    Robert, R.V.D.; Ormrod, G.T.W.

    1982-01-01

    An on-line analyser to monitor the gold in solutions from the carbon-in-pulp process is described. The automatic system is based on the delivery of filtered samples of the solutions to a distribution valve for measurement by flameless atomic-absorption spectrophotometry. The samples is introduced by the aerosol-deposition method. Operation of the analyser on a pilot plant and on a full-scale carbon-in-pulp plant has shown that the system is economically feasible and capable of providing a continuous indication of the efficiency of the extraction process

  18. The effect of self-absorption in hollow cathode lamp on its temperature

    International Nuclear Information System (INIS)

    Sobhanian, S.; Naghshara, H.

    2014-01-01

    It has been shown experimentally that even a small error in the calculation of the temperature inside the hollow-cathode lamp (HCL) and the current applied to the lamp, may cause a tremendous error in determination of the absorption ratio in optical resonance absorption (ORA) method. This effect is intensified nonlinearity for large absorption ratios. If a higher current is applied to a copper hollow cathode lamp, the copper density inside the lamp is increasing rapidly. Due to the cylindrical (axisymmetric) form of the lamp, the density of atoms around the main axis of the lamp becomes greater than that near the internal wall. In this case the auto-absorption (or self-absorption) is occurred and as its result, the emission spectrum produced by copper atoms is locally absorbed before going out from the lamp. This absorption is stronger near the main axis compared with the areas near the wall because of the Gaussian profile of the spectral line. Two different Cu atoms ground state lines with the similar lower state (327.4 nm and 324.7 nm) are used in this work as optical resonance absorption and the absorption coefficient is obtained for three different pressures (0.6, 4.5 and 14 µbar). The best values for copper HCL temperature and for maximum HCL current were found respectively 450 K, and 5mA. (author)

  19. Effects of collisions on linear and non-linear spectroscopic line shapes

    International Nuclear Information System (INIS)

    Berman, P.R.

    1978-01-01

    A fundamental physical problem is the determination of atom-atom, atom-molecule and molecule-molecule differential and total scattering cross sections. In this work, a technique for studying atomic and molecular collisions using spectroscopic line shape analysis is discussed. Collisions occurring within an atomic or molecular sample influence the sample's absorptive or emissive properties. Consequently the line shapes associated with the linear or non-linear absorption of external fields by an atomic system reflect the collisional processes occurring in the gas. Explicit line shape expressions are derived characterizing linear or saturated absorption by two-or three-level 'active' atoms which are undergoing collisions with perturber atoms. The line shapes may be broadened, shifted, narrowed, or distorted as a result of collisions which may be 'phase-interrupting' or 'velocity-changing' in nature. Systematic line shape studies can be used to obtain information on both the differential and total active atom-perturber scattering cross sections. (Auth.)

  20. Simultaneous multi-element atomic absorption system using photodiode array detector

    International Nuclear Information System (INIS)

    Tong, S.L.; Chin, K.S.

    1994-01-01

    A photodiode array (PDA) detector-multichannel analyser (MCA) system has been coupled to a flame and a graphite furnace atomiser and tested for simultaneous multielement atomic absorption analysis. Multielement hollow cathode lamps (HCL) are used as light source. Spectral lines are dispersed through a spectrograph with triple gratings and detected by a 25.4 mm PDA detector consisting of 1024 elements. The optical MCA system is capable of recording multiple spectra spanned by the spectrograph/PDA. The transmitted intensity spectra obtained for the standard and analyte solutions during flame or graphite furnace atomisation are converted to absorbance spectra using the MCA software provided. Results from the comparison studies show that the linear range and sensitivities for Ni-Co-Fe and Cu-Cr obtained from the simultaneous measurements are within the same order of magnitudes as those from conventional single element determinations using photomultiplier tube detection. The study also shows that non-atomic absorption can be readily corrected by a two-line method where non-atomic absorption lines can be chosen from the spectra recorded simultaneously. The proposed system has been evaluated for the determination of trace elements using NBS standard reference water SRM 1643b

  1. New method of interpretation of the solar spectrum lines

    International Nuclear Information System (INIS)

    Sitnik, G.F.

    1975-01-01

    Close triplet lines, which appear from a common low level or from low sublevels with small energy difference are used. It is supposed that for such lines both the function of the source in line and the frequency dependence of the selective coefficient of absorption are the same over any depth of the region of line production in the atmosphere and change with the depth equally. The residual intensities of some lines of the triplet, which are measured for every line at a number of profile points (at the same distance from its center and at different distances from the solar limb center), serve as initial material. The intensities are expressed in terms of the intensity of the continuous spectrum in the center of the solar limb for the average wave length of the triplet interval. Such observations avoid the usual assumption about the source function constancy in line inside the line. On the contrary, the frequency dependence of this function is clarified by the use of this method. Calculations make it possible to determine the source function in line and its long-wave dependence inside the line; to derive a solar atmosphere model and to determine the source function in the continuous spectrum in accordance with observations at profile points in its middle part and in the wing; to find the relation between the selective and continuous absorption coefficients in the dependence on the optical depth in the continuous spectrum; and to find the long-wave dependences of coefficients for both the selective absorption and the selective emission at different optical depths

  2. CIRCUMSTELLAR SHELLS IN ABSORPTION IN TYPE Ia SUPERNOVAE

    International Nuclear Information System (INIS)

    Borkowski, Kazimierz J.; Blondin, John M.; Reynolds, Stephen P.

    2009-01-01

    Progenitors of Type Ia supernovae (SNe) have been predicted to modify their ambient circumstellar (CSM) and interstellar environments through the action of their powerful winds. While there is X-ray and optical evidence for circumstellar interaction in several remnants of Type Ia SNe, widespread evidence for such interaction in Type Ia SNe themselves has been lacking. We consider prospects for the detection of CSM shells that have been predicted to be common around Type Ia SNe. Such shells are most easily detected in Na I absorption lines. Variable (declining) absorption is expected to occur soon after the explosion, primarily during the SN rise time, for shells located within ∼1-10 pc of a SN. The distance of the shell from the SN can be determined by measuring the timescale for line variability.

  3. Radiation trapping in atomic absorption spectroscopy at lead determination in different matricies

    International Nuclear Information System (INIS)

    El-Gohary, Z.

    2005-01-01

    The determination of lead by flame atomic absorption analysis in the presence of Sn and Fe atoms and different matrices such as OH and SO 3 was investigated with the objective of understanding the spectral interference processes at the analytical lines 283.31 nm for a wide range of concentration. The radiation trapping factor was interpreted and evaluated assuming Voigt distribution of the atomic and rotational lines in the flame. The radiation trapping factor was increased by increasing the number density (plasma of the absorbing medium is optically thick). In plasma, there is a certain point of equilibrium between the trapping and the escaping of radiation, which is relevant to 50% of absorption. The spectral background interference can cause a variation of the number density at equilibrium point as a result of the degree of overlap with the analytical line. The spectral background interference can be easily avoided by using another resonance absorption line for the analysis. The chemical modification of the matrix is applied to minimize the interference effect. Nitric acid, ammonium nitrate and magnesium nitrate are most commonly recommended as matrix modifiers

  4. Molecular and Recombination Lines in the Central Region of Sagittarius B2

    Science.gov (United States)

    Curtis, J.; Langston, G.

    2005-12-01

    We present observations of recombination and molecular lines towards Sgr B2 in the frequency range 12.4 to 15.0 GHz. In this frequency range, Hα , β , and γ lines, Heα recombination lines and emission from the SO molecule are detected. Molecular absorption lines from OH, H2CO, and CH3CO are detected at velocity 62±3 km/s. Measurements of the line widths and intensities are presented for the central region of Sgr B2. We detect two previously un-reported molecular absorption lines at 12388.0 and 14625.8 MHz (v=0. in LSR Frame). For selected recombination and molecular lines, we present images of a 10x10 arc-minute region centered on Sgr B2(M). We discuss the sources of three H2CO absorption features detected at 62±3, 6±5, and 100±10 km/s. This was done as a summer REU project in 2005 at the National Radio Astronomy Observatory's Green Bank site, and was funded by the National Science Foundation's REU program.

  5. Photoionization Modeling and the K Lines of Iron

    Science.gov (United States)

    Kallman, T. R.; Palmeri, P.; Bautista, M. A.; Mendoza, C.; Krolik, J. H.

    2004-01-01

    We calculate the efficiency of iron K line emission and iron K absorption in photoionized models using a new set of atomic data. These data are more comprehensive than those previously applied to the modeling of iron K lines from photoionized gases, and allow us to systematically examine the behavior of the properties of line emission and absorption as a function of the ionization parameter, density and column density of model constant density clouds. We show that, for example, the net fluorescence yield for the highly charged ions is sensitive to the level population distribution produced by photoionization, and these yields are generally smaller than those predicted assuming the population is according to statistical weight. We demonstrate that the effects of the many strongly damped resonances below the K ionization thresholds conspire to smear the edge, thereby potentially affecting the astrophysical interpretation of absorption features in the 7-9 keV energy band. We show that the centroid of the ensemble of K(alpha) lines, the K(beta) energy, and the ratio of the K(alpha(sub 1)) to K(alpha(sub 2)) components are all diagnostics of the ionization parameter of our model slabs.

  6. Development of automobile brake lining using pulverized cow hooves

    Directory of Open Access Journals (Sweden)

    Katsina C. BALA

    2016-06-01

    Full Text Available Asbestos has been used for so long as automobile brake lining material because of its good physical and chemical properties. However, due to the health hazard associated with its handling, it has lost favour and several alternative materials are being increasingly used. Asbestos-free brake lining was developed in this work using pulverized cow hooves along with epoxy resin, barium sulphate, graphite and aluminium oxide. This was with a view to exploiting the characteristics of cow hooves, which are largely discarded as waste materials to replace asbestos which has been found to be carcinogenic. Samples of brake linings were produced using compressive moulding in which the physical and mechanical properties of the samples were studied. The results obtained showed that proper bonding was achieved as the percentage by weight of epoxy resin increased and percentage by weight of pulverized cow hooves decreased. The hardness, compressive strength, coefficient of friction, water and oil absorption, relative density and wear rate of the brake linings were determined and compared with existing brake lining properties. The result indicates that pulverized cow hooves can be used as brake lining material for automobiles.

  7. Krohne Flow Indicator and High Flow Alarm - Local Indicator and High Flow Alarm of Helium Flow from the SCHe Purge Lines C and D to the Process Vent

    International Nuclear Information System (INIS)

    MISKA, C.R.

    2000-01-01

    Flow Indicators/alarms FI/FSH-5*52 and -5*72 are located in the process vent lines connected to the 2 psig SCHe purge lines C and D. They monitor the flow from the 2 psig SCHe purge going to the process vent. The switch/alarm is non-safety class GS

  8. Airborne differential absorption lidar system for measurements of atmospheric water vapor and aerosols

    Science.gov (United States)

    Carter, Arlen F.; Allen, Robert J.; Mayo, M. Neale; Butler, Carolyn F.; Grossman, Benoist E.; Ismail, Syed; Grant, William B.; Browell, Edward V.; Higdon, Noah S.; Mayor, Shane D.; hide

    1994-01-01

    An airborne differential absorption lidar (DIAL) system has been developed at the NASA Langley Research Center for remote measurements of atmospheric water vapor (H2O) and aerosols. A solid-state alexandrite laser with a 1-pm linewidth and greater than 99.85% spectral purity was used as the on-line transmitter. Solid-state avalanche photodiode detector technology has replaced photomultiplier tubes in the receiver system, providing an average increase by a factor of 1.5-2.5 in the signal-to-noise ratio of the H2O measurement. By incorporating advanced diagnostic and data-acquisition instrumentation into other subsystems, we achieved additional improvements in system operational reliability and measurement accuracy. Laboratory spectroscopic measurements of H2O absorption-line parameters were performed to reduce the uncertainties in our knowledge of the absorption cross sections. Line-center H2O absorption cross sections were determined, with errors of 3-6%, for more than 120 lines in the 720-nm region. Flight tests of the system were conducted during 1989-1991 on the NASA Wallops Flight Facility Electra aircraft, and extensive intercomparison measurements were performed with dew-point hygrometers and H2O radiosondes. The H2O distributions measured with the DIAL system differed by less than 10% from the profiles determined with the in situ probes in a variety of atmospheric conditions.

  9. Aerosol Angstrom Absorption Coefficient Comparisons during MILAGRO.

    Science.gov (United States)

    Marley, N. A.; Marchany-Rivera, A.; Kelley, K. L.; Mangu, A.; Gaffney, J. S.

    2007-12-01

    Measurements of aerosol absorption were obtained as part of the MAX-Mex component of the MILAGRO field campaign at site T0 (Instituto Mexicano de Petroleo in Mexico City) by using a 7-channel aethalometer (Thermo- Anderson) during the month of March, 2006. The absorption measurements obtained in the field at 370, 470, 520, 590, 660, 880, and 950 nm were used to determine the aerosol Angstrom absorption exponents by linear regression. Since, unlike other absorbing aerosol species (e.g. humic like substances, nitrated PAHs), black carbon absorption is relatively constant from the ultraviolet to the infrared with an Angstrom absorption exponent of -1 (1), a comparison of the Angstrom exponents can indicate the presence of aerosol components with an enhanced UV absorption over that expected from BC content alone. The Angstrom exponents determined from the aerosol absorption measurements obtained in the field varied from - 0.7 to - 1.3 during the study and was generally lower in the afternoon than the morning hours, indicating an increase in secondary aerosol formation and photochemically generated UV absorbing species in the afternoon. Twelve-hour integrated samples of fine atmospheric aerosols (Petroleo (IMP) and CENICA.

  10. Spectral control of an alexandrite laser for an airborne water-vapor differential absorption lidar system

    Science.gov (United States)

    Ponsardin, Patrick; Grossmann, Benoist E.; Browell, Edward V.

    1994-01-01

    A narrow-linewidth pulsed alexandrite laser has been greatly modified for improved spectral stability in an aircraft environment, and its operation has been evaluated in the laboratory for making water-vapor differential absorption lidar measurements. An alignment technique is described to achieve the optimum free spectral range ratio for the two etalons inserted in the alexandrite laser cavity, and the sensitivity of this ratio is analyzed. This technique drastically decreases the occurrence of mode hopping, which is commonly observed in a tunable, two-intracavity-etalon laser system. High spectral purity (greater than 99.85%) at 730 nm is demonstrated by the use of a water-vapor absorption line as a notch filter. The effective cross sections of 760-nm oxygen and 730-nm water-vapor absorption lines are measured at different pressures by using this laser, which has a finite linewidth of 0.02 cm(exp -1) (FWHM). It is found that for water-vapor absorption linewidths greater than 0.04 cm(exp -1) (HWHM), or for altitudes below 10 km, the laser line can be considered monochromatic because the measured effective absorption cross section is within 1% of the calculated monochromatic cross section. An analysis of the environmental sensitivity of the two intracavity etalons is presented, and a closed-loop computer control for active stabilization of the two intracavity etalons in the alexandrite laser is described. Using a water-vapor absorption line as a wavelength reference, we measure a long-term frequency drift (approximately 1.5 h) of less than 0.7 pm in the laboratory.

  11. Analysis of gaseous ammonia (NH3) absorption in the visible spectrum of Jupiter

    Science.gov (United States)

    Irwin, Patrick G. J.; Bowles, Neil; Braude, Ashwin S.; Garland, Ryan; Calcutt, Simon

    2018-03-01

    Observations of the visible/near-infrared reflectance spectrum of Jupiter have been made with the Very Large Telescope (VLT) Multi Unit Spectroscopic Explorer (MUSE) instrument in the spectral range 0.48-0.93 μm in support of the NASA/Juno mission. These spectra contain spectral signatures of gaseous ammonia (NH3), whose abundance above the cloud tops can be determined if we have reliable information on its absorption spectrum. While there are a number of sources of NH3 absorption data in this spectral range, they cover small sub-ranges, which do not necessarily overlap and have been determined from a variety of sources. There is thus considerable uncertainty regarding the consistency of these different sources when modelling the reflectance of the entire visible/near-IR range. In this paper we analyse the VLT/MUSE observations of Jupiter to determine which sources of ammonia absorption data are most reliable. We find that the band model coefficients of Bowles et al. (2008) provide, in general, the best combination of reliability and wavelength coverage over the MUSE range. These band data appear consistent with ExoMOL ammonia line data of Yurchenko et al. (2011), at wavelengths where they overlap, but these latter data do not cover the ammonia absorption bands at 0.79 and 0.765 μm, which are prominent in our MUSE observations. However, we find the band data of Bowles et al. (2008) are not reliable at wavelengths less than 0.758 μm. At shorter wavelengths we find the laboratory observations of Lutz and Owen (1980) provide a good indication of the position and shape of the ammonia absorptions near 0.552 μm and 0.648 μm, but their absorption strengths appear inconsistent with the band data of Bowles et al. (2008) at longer wavelengths. Finally, we find that the line data of the 0.648 μm absorption band of Giver et al. (1975) are not suitable for modelling these data as they account for only 17% of the band absorption and cannot be extended reliably to the cold

  12. Molecular absorption spectra of beryllium, cerium, lanthanum, iron, and platinum salts

    International Nuclear Information System (INIS)

    Daidoji, Hidehiro

    1980-01-01

    The absorption spectra of some salts of beryllium, cerium, lanthanum, iron and platinum in air-acetylene flame were measured in the wavelength range from 200 to 400 nm. A Hitachi 207 type atomic absorption spectrophotometer was used. A deuterium lamp, a home-made continuous radiation lamp and some hollow cathode lamps were used as light sources. The new molecular absorption spectra of cerium, lanthanum and platinum and the absorption spectra due to Be(OH) 2 , LaO, PtH, FeO and FeCl in 200-400 nm region were obtained. Emission spectra of CeO, LaO and FeOH were also obtained. These molecular absorption bands were estimated as absorption errors of maximum 15 times to the sensitivity of each elements in atomic absorption spectrometry. In addition, spectral line interferences of iron were observed in atomic absorption spectrometry of Zn, Cd, Ni, Cu and Cr. (author)

  13. The hydrogen-poor superluminous supernova iPTF 13ajg and its host galaxy in absorption and emission

    Energy Technology Data Exchange (ETDEWEB)

    Vreeswijk, Paul M.; Gal-Yam, Avishay; De Cia, Annalisa; Rubin, Adam; Yaron, Ofer; Tal, David; Ofek, Eran O. [Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Rehovot 7610001 (Israel); Savaglio, Sandra [Max Planck Institute for Extraterrestrial Physics, D-85748 Garching bei München (Germany); Quimby, Robert M. [Kavli Institute for the Physics and Mathematics of the Universe (WPI), Todai Institutes for Advanced Study, The University of Tokyo 5-1-5 Kashiwanoha, Kashiwa-shi, Chiba 277-8583 (Japan); Sullivan, Mark [School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom); Cenko, S. Bradley; Filippenko, Alexei V.; Clubb, Kelsey I. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Perley, Daniel A.; Cao, Yi [Astronomy Department, California Institute of Technology, MC 249-17, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Taddia, Francesco; Sollerman, Jesper; Leloudas, Giorgos [Department of Astronomy, The Oskar Klein Center, Stockholm University, AlbaNova 10691 Stockholm (Sweden); Arcavi, Iair [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive, Suite 102, Goleta, CA 93117 (United States); Kasliwal, Mansi M., E-mail: paul.vreeswijk@weizmann.ac.il [The Observatories, Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); and others

    2014-12-10

    We present imaging and spectroscopy of a hydrogen-poor superluminous supernova (SLSN) discovered by the intermediate Palomar Transient Factory, iPTF 13ajg. At a redshift of z = 0.7403, derived from narrow absorption lines, iPTF 13ajg peaked at an absolute magnitude of M {sub u,} {sub AB} = –22.5, one of the most luminous supernovae to date. The observed bolometric peak luminosity of iPTF 13ajg is 3.2 × 10{sup 44} erg s{sup –1}, while the estimated total radiated energy is 1.3 × 10{sup 51} erg. We detect narrow absorption lines of Mg I, Mg II, and Fe II, associated with the cold interstellar medium in the host galaxy, at two different epochs with X-shooter at the Very Large Telescope. From Voigt profile fitting, we derive the column densities log N(Mg I) =11.94 ± 0.06, log N(Mg II) =14.7 ± 0.3, and log N(Fe II) =14.25 ± 0.10. These column densities, as well as the Mg I and Mg II equivalent widths of a sample of hydrogen-poor SLSNe taken from the literature, are at the low end of those derived for gamma-ray bursts (GRBs) whose progenitors are also thought to be massive stars. This suggests that the environments of hydrogen-poor SLSNe and GRBs are different. From the nondetection of Fe II fine-structure absorption lines, we derive a lower limit on the distance between the supernova and the narrow-line absorbing gas of 50 pc. The neutral gas responsible for the absorption in iPTF 13ajg exhibits a single narrow component with a low velocity width, ΔV = 76 km s{sup –1}, indicating a low-mass host galaxy. No host galaxy emission lines are detected, leading to an upper limit on the unobscured star formation rate (SFR) of SFR{sub [O} {sub II]}<0.07M{sub ⊙}yr{sup −1}. Late-time imaging shows the iPTF 13ajg host galaxy to be faint, with g {sub AB} ≈ 27.0 and R {sub AB} ≥ 26.0 mag, corresponding to M {sub B,} {sub Vega} ≳ –17.7 mag.

  14. Absorption cross-section measurements of methane, ethane, ethylene and methanol at high temperatures

    KAUST Repository

    Alrefae, Majed

    2014-09-01

    Mid-IR absorption cross-sections are measured for methane, ethane, ethylene and methanol over 2800-3400 cm-1 (2.9-3.6 μm) spectral region. Measurements are carried out using a Fourier-Transform-Infrared (FTIR) spectrometer with temperatures ranging 296-1100 K and pressures near atmospheric. As temperature increases, the peak cross-sections decrease but the wings of the bands increase as higher rotational lines appear. Integrated band intensity is also calculated over the measured spectral region and is found to be a very weak function of temperature. The absorption cross-sections of the relatively small fuels studied here show dependence on the bath gas. This effect is investigated by studying the variation of absorption cross-sections at 3.392 μm using a HeNe laser in mixtures of fuel and nitrogen, argon, or helium. Mixtures of fuel with He have the highest value of absorption cross-sections followed by Ar and N2. Molecules with narrow absorption lines, such as methane and methanol, show strong dependence on bath gas than molecules with relatively broader absorption features i.e. ethane and ethylene. © 2014 Elsevier Inc. All rights reserved.

  15. Subgap Absorption in Conjugated Polymers

    Science.gov (United States)

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

    1991-01-01

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

  16. A CHANDRA SURVEY OF THE X-RAY PROPERTIES OF BROAD ABSORPTION LINE RADIO-LOUD QUASARS

    International Nuclear Information System (INIS)

    Miller, B. P.; Brandt, W. N.; Garmire, G. P.; Gibson, R. R.; Shemmer, O.

    2009-01-01

    This work presents the results of a Chandra study of 21 broad absorption line (BAL) radio-loud quasars (RLQs). We conducted a Chandra snapshot survey of 12 bright BAL RLQs selected from Sloan Digital Sky Survey Data/Faint Images of the Radio Sky data and possessing a wide range of radio and C IV absorption properties. Optical spectra were obtained nearly contemporaneously with the Hobby-Eberly Telescope; no strong flux or BAL variability was seen between epochs. In addition to the snapshot targets, we include in our sample nine additional BAL RLQs possessing archival Chandra coverage. We compare the properties of (predominantly high-ionization) BAL RLQs to those of non-BAL RLQs as well as to BAL radio-quiet quasars (RQQs) and non-BAL RQQs for context. All 12 snapshots and 8/9 archival BAL RLQs are detected, with observed X-ray luminosities less than those of non-BAL RLQs having comparable optical/UV luminosities by typical factors of 4.1-8.5. (BAL RLQs are also X-ray weak by typical factors of 2.0-4.5 relative to non-BAL RLQs having both comparable optical/UV and radio luminosities.) However, BAL RLQs are not as X-ray weak relative to non-BAL RLQs as are BAL RQQs relative to non-BAL RQQs. While some BAL RLQs have harder X-ray spectra than typical non-BAL RLQs, some have hardness ratios consistent with those of non-BAL RLQs, and there does not appear to be a correlation between X-ray weakness and spectral hardness, in contrast to the situation for BAL RQQs. RLQs are expected to have X-ray continuum contributions from both accretion-disk corona and small-scale jet emission. While the entire X-ray continuum in BAL RLQs cannot be obscured to the same degree as in BAL RQQs, we calculate that the jet is likely partially covered in many BAL RLQs. We comment briefly on implications for geometries and source ages in BAL RLQs.

  17. Quantum quench of Kondo correlations in optical absorption.

    Science.gov (United States)

    Latta, C; Haupt, F; Hanl, M; Weichselbaum, A; Claassen, M; Wuester, W; Fallahi, P; Faelt, S; Glazman, L; von Delft, J; Türeci, H E; Imamoglu, A

    2011-06-29

    The interaction between a single confined spin and the spins of an electron reservoir leads to one of the most remarkable phenomena of many-body physics--the Kondo effect. Electronic transport measurements on single artificial atoms, or quantum dots, have made it possible to study the effect in great detail. Here we report optical measurements on a single semiconductor quantum dot tunnel-coupled to a degenerate electron gas which show that absorption of a single photon leads to an abrupt change in the system Hamiltonian and a quantum quench of Kondo correlations. By inferring the characteristic power-law exponents from the experimental absorption line shapes, we find a unique signature of the quench in the form of an Anderson orthogonality catastrophe, induced by a vanishing overlap between the initial and final many-body wavefunctions. We show that the power-law exponent that determines the degree of orthogonality can be tuned using an external magnetic field, which unequivocally demonstrates that the observed absorption line shape originates from Kondo correlations. Our experiments demonstrate that optical measurements on single artificial atoms offer new perspectives on many-body phenomena previously studied using transport spectroscopy only.

  18. Subgap absorption in conjugated polymers

    Energy Technology Data Exchange (ETDEWEB)

    Sinclair, M.; Seager, C.H. (Sandia National Labs., Albuquerque, NM (USA)); McBranch, D.; Heeger, A.J. (California Univ., Santa Barbara, CA (USA)); Baker, G.L. (Bell Communications Research, Inc., Red Bank, NJ (USA))

    1991-01-01

    Along with X{sup (3)}, the magnitude of the optical absorption in the transparent window below the principal absorption edge is an important parameter which will ultimately determine the utility of conjugated polymers in active integrated optical devices. With an absorptance sensitivity of < 10{sup {minus}5}, Photothermal Deflection Spectroscopy (PDS) is ideal for determining the absorption coefficients of thin films of transparent'' materials. We have used PDS to measure the optical absorption spectra of the conjugated polymers poly(1,4-phenylene-vinylene) (and derivitives) and polydiacetylene-4BCMU in the spectral region from 0.55 eV to 3 eV. Our spectra show that the shape of the absorption edge varies considerably from polymer to polymer, with polydiacetylene-4BCMU having the steepest absorption edge. The minimum absorption coefficients measured varied somewhat with sample age and quality, but were typically in the range 1 cm{sup {minus}1} to 10 cm{sup {minus}1}. In the region below 1 eV, overtones of C-H stretching modes were observed, indicating that further improvements in transparency in this spectral region might be achieved via deuteration of fluorination. 11 refs., 4 figs.

  19. Epigenomic diversity of colorectal cancer indicated by LINE-1 methylation in a database of 869 tumors

    Directory of Open Access Journals (Sweden)

    Schernhammer Eva S

    2010-05-01

    Full Text Available Abstract Background Genome-wide DNA hypomethylation plays a role in genomic instability and carcinogenesis. LINE-1 (L1 retrotransposon constitutes a substantial portion of the human genome, and LINE-1 methylation correlates with global DNA methylation status. LINE-1 hypomethylation in colon cancer has been strongly associated with poor prognosis. However, whether LINE-1 hypomethylators constitute a distinct cancer subtype remains uncertain. Recent evidence for concordant LINE-1 hypomethylation within synchronous colorectal cancer pairs suggests the presence of a non-stochastic mechanism influencing tumor LINE-1 methylation level. Thus, it is of particular interest to examine whether its wide variation can be attributed to clinical, pathologic or molecular features. Design Utilizing a database of 869 colorectal cancers in two prospective cohort studies, we constructed multivariate linear and logistic regression models for LINE-1 methylation (quantified by Pyrosequencing. Variables included age, sex, body mass index, family history of colorectal cancer, smoking status, tumor location, stage, grade, mucinous component, signet ring cells, tumor infiltrating lymphocytes, CpG island methylator phenotype (CIMP, microsatellite instability, expression of TP53 (p53, CDKN1A (p21, CTNNB1 (β-catenin, PTGS2 (cyclooxygenase-2, and FASN, and mutations in KRAS, BRAF, and PIK3CA. Results Tumoral LINE-1 methylation ranged from 23.1 to 90.3 of 0-100 scale (mean 61.4; median 62.3; standard deviation 9.6, and distributed approximately normally except for extreme hypomethylators [LINE-1 methylation Conclusions LINE-1 extreme hypomethylators appear to constitute a previously-unrecognized, distinct subtype of colorectal cancers, which needs to be confirmed by additional studies. Our tumor LINE-1 methylation data indicate enormous epigenomic diversity of individual colorectal cancers.

  20. Antimony orthophosphate glasses with large nonlinear refractive indices, low two-photon absorption coefficients, and ultrafast response

    International Nuclear Information System (INIS)

    Falcao-Filho, E.L.; Araujo, Cid B. de; Bosco, C.A.C.; Maciel, G.S.; Acioli, L.H.; Nalin, M.; Messaddeq, Y.

    2005-01-01

    Antimony glasses based on the composition Sb 2 O 3 -SbPO 4 were prepared and characterized. The samples present high refractive index, good transmission from 380 to 2000 nm, and high thermal stability. The nonlinear refractive index, n 2 , of the samples was studied using the optical Kerr shutter technique at 800 nm. The third-order correlation signals between pump and probe pulses indicate ultrafast response ( 2 was observed by adding lead oxide to the Sb 2 O 3 -SbPO 4 composition. Large values of n 2 ≅10 -14 cm 2 /W and negligible two-photon absorption coefficients (smaller than 0.01 cm/GW) were determined for all samples. The glass compositions studied present appropriate figure-of-merit for all-optical switching applications

  1. The detailed balance requirement and general empirical formalisms for continuum absorption

    Science.gov (United States)

    Ma, Q.; Tipping, R. H.

    1994-01-01

    Two general empirical formalisms are presented for the spectral density which take into account the deviations from the Lorentz line shape in the wing regions of resonance lines. These formalisms satisfy the detailed balance requirement. Empirical line shape functions, which are essential to provide the continuum absorption at different temperatures in various frequency regions for atmospheric transmission codes, can be obtained by fitting to experimental data.

  2. Concentration-modulated absorption spectroscopy and the triplet state: Photoinduced absorption/bleaching in erythrosin B, rose bengal and eosin y

    Science.gov (United States)

    Jones, W. Jeremy; Grofcsik, Andras; Kubinyi, Miklos; Thomas, Daniel

    2006-07-01

    The pump and probe method concentration-modulated absorption spectroscopy has been applied for studying the triplet characteristics of dyes erythrosin B, rose bengal and eosin y in ethanol solutions. Using the 514.5 and 488 nm lines of an argon ion laser for pump and probe beams, respectively, photoinduced bleaching for erythrosin B and eosin y and photoinduced absorption for rose bengal have been observed. The theory developed for describing the interactions of dye molecules of strong triplet forming ability with continuous wave pump and probe beams of Gaussian beam profiles has been tested by analysing the probe power gain or loss at different positions along the optical path of the focused collinear beams. From the gain-modulation frequency curves triplet absorption cross sections and the lifetimes of the triplet states have been determined.

  3. Sound absorption effects in a rectangular enclosure with the foamed aluminum sheet absorber

    International Nuclear Information System (INIS)

    Oh, Jae Eung; Chung, Jin Tai; Kim, Sang Hun; Chung, Kyung Ryul

    1998-01-01

    For the purpose of finding out the optimal thickness of sound absorber and the sound absorption effects due to the selected thickness at an interested frequency range, the analytical study identifies the interior and exterior sound field characteristics of a rectangular enclosure with foamed aluminum lining and the experimental verification is performed with random noise input. By using a two-microphone impedance tube, we measure experimentally the absorption coefficient and the impedance of simple sound absorbing materials. Measured acoustical parameters of the test samples are applied to the theoretical analysis to predict sound pressure field in the cavity. The sound absorption effects from measurements are compared to predicted ones in both cases with and without foamed aluminum lining in the cavity of the rectangular enclosure

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

    Science.gov (United States)

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

    2016-04-05

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

  5. New 3D gas density maps of NaI and CaII interstellar absorption within 300 pc

    Science.gov (United States)

    Welsh, B. Y.; Lallement, R.; Vergely, J.-L.; Raimond, S.

    2010-02-01

    Aims: We present new high resolution (R > 50 000) absorption measurements of the NaI doublet (5889-5895 Å) along 482 nearby sight-lines, in addition to 807 new measurements of the CaII K (3933 Å) absorption line. We have combined these new data with previously reported measurements to produce a catalog of absorptions towards a total of 1857 early-type stars located within 800 pc of the Sun. Using these data we have determined the approximate 3-dimensional spatial distribution of neutral and partly ionized interstellar gas density within a distance-cube of 300 pc from the Sun. Methods: All newly recorded spectra were analyzed by means of a multi-component line profile-fitting program, in most cases using simultaneous fits to the line doublets. Normalized absorption profiles were fitted by varying the velocity, doppler width and column density for all intervening interstellar clouds. The resulting total column densities were then used in conjunction with the Hipparcos distances of the target stars to construct inversion maps of the 3D spatial density distribution of the NaI and CaII bearing gas. Results: A plot of the equivalent width of NaI versus distance reveals a wall of neutral gas at ~80 pc that can be associated with the boundary wall to the central rarefied Local Cavity region. In contrast, a similar plot for the equivalent width of CaII shows no sharply increasing absorption at 80 pc, but instead we observe a slowly increasing value of CaII equivalent width with increasing sight-line distance sampled. Low values for the volume density of NaI (nNaI values in the range 10-8 >nNaI > 10-10 cm-3 are found for sight-lines with distance >300 pc. Both high and low values of the volume density of CaII (nCaII) are found for sight-lines 100 pc a value of nCaII ~ 10-9 cm-3 is typical for most sight-lines, indicating that the distribution of CaII bearing gas is fairly uniform throughout the general ISM. Our three maps of the 3D spatial distribution of local neutral Na

  6. Distortion of absorption-line velocity curves due to x-ray heating in x-ray binaries

    International Nuclear Information System (INIS)

    Milgrom, M.

    1976-01-01

    The effects of X-ray heating on the measured absorption line velocities, in X-ray binaries with low X-rays to optical luminosities ratio are considered. These effects may be appreciable even for such binaries where the effect of X-ray heating on the light-curve is negligible. The effects are studied qualitatively and suggest possible ways to partially eliminate the systematic errors introduced by them. The individual systems Cyg x-1 and SMC x-1 are treated and the results of numerical calculations are presented for them. For Cyg x-1 it is found that the effect is detectable during the X-ray 'high' state in all regions of the spectrum. During the 'low' state it may be important in the red region of the spectrum. The results for the case in which soft X-ray fluxes (E < or approximately .4 keV, suggested by theoretical models) are present are also given. For SMC x-1 a strong effect for Hα, Hβ, Hγ had been found. This effect may be responsible for the observed variable velocity curve. We also find for SMC x-1 that the average X-ray intensity falling on the primary must be considerably smaller than what is derived from the detected flux, or else the effect is too large. (author)

  7. Laser frequency locking based on the normal and abnormal saturated absorption spectroscopy of 87Rb

    International Nuclear Information System (INIS)

    Wan Jian-Hong; Liu Chang; Wang Yan-Hui

    2016-01-01

    We present a practical method to avoid the mis-locking phenomenon in the saturated-absorption-spectrum laser-frequency-locking system and set up a simple theoretical model to explain the abnormal saturated absorption spectrum. The method uses the normal and abnormal saturated absorption spectra of the same transition 5 2 S 1/2 , F = 2–5 2 P 3/2 , F′ = 3 saturated absorption of the 87 Rb D 2 resonance line. After subtracting these two signals with the help of electronics, we can obtain a spectrum with a single peak to lock the laser. In our experiment, we use the normal and inverse signals of the transitions 5 2 S 1/2 , F = 2–5 2 P 3/2 , F′ = 3 saturated absorption of the 87 Rb D 2 resonance line to lock a 780-nm distributed feedback (DFB) diode laser. This method improves the long-term locking performance and is suitable for other kinds of diode lasers. (paper)

  8. Transmission line model and fields analysis of metamaterial absorber in the terahertz band.

    Science.gov (United States)

    Wen, Qi-Ye; Xie, Yun-Song; Zhang, Huai-Wu; Yang, Qing-Hui; Li, Yuan-Xun; Liu, Ying-Li

    2009-10-26

    Metamaterial (MM) absorber is a novel device to provide near-unity absorption to electromagnetic wave, which is especially important in the terahertz (THz) band. However, the principal physics of MM absorber is still far from being understood. In this work, a transmission line (TL) model for MM absorber was proposed, and with this model the S-parameters, energy consumption, and the power loss density of the absorber were calculated. By this TL model, the asymmetric phenomenon of THz absorption in MM absorber is unambiguously demonstrated, and it clarifies that strong absorption of this absorber under studied is mainly related to the LC resonance of the split-ring-resonator structure. The distribution of power loss density in the absorber indicates that the electromagnetic wave is firstly concentrated into some specific locations of the absorber and then be strongly consumed. This feature as electromagnetic wave trapper renders MM absorber a potential energy converter. Based on TL model, some design strategies to widen the absorption band were also proposed for the purposes to extend its application areas.

  9. Synthesis, characterization and microwave absorption of carbon-coated Cu nanocapsules

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yuping [Center for Engineering Practice and Innovation Education, Anhui University of Technology, Maanshan, (China); Feng, Chao; Liu, Xianguo; Jin, Chuangui, E-mail: liuxianguohugh@gmail.com [School of Materials Science and Engineering, Anhui University of Technology, Maanshan (China); Or, Siu Wing [Department of Electrical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, (Hong Kong)

    2014-03-15

    The microstructure and microwave absorption of carbon-coated Cu nanocapsules have been investigated. Carbon-coated Cu nanocapsules have been synthesized by an arc-discharge method. The paraffin-Cu/C nanocapsules composite shows excellent electromagnetic (EM) absorption properties. An optimal reflection loss (RL) value of –40.0 dB is reached at 10.52 GHz for a layer 1.9 mm thickness. RL exceeding –20 dB can be realized in any interval within the 1-18 GHz range by choosing an appropriate thickness of the absorbent layer between 1.1 and 10.0 mm. Theoretical simulation for the microwave absorption using the transmission line theory agrees reasonably well with the experimental results. The EM-wave absorption properties of nanocapsules materials are illustrated by means of an absorption-tube-map. The carbon-coated Cu nano capsule is an attractive candidate for EM-wave absorption, which significantly enriches the family of EM-wave nano absorbents. (author)

  10. Analysis of the lambda 5696 Carbon III line in the O stars

    International Nuclear Information System (INIS)

    Cardona-Nunez, O.

    1978-01-01

    Lines of twice-ionized Carbon, specifically lambda 5695 and lambda 8500, in the O stars were analyzed on the basis of a detailed solution of the coupled statistical-equilibrium and transfer equations for a multilevel, multiline, multi-ion ensemble. It is significant that these plane-parallel non-LTE statistical equilibrium calculations reproduce successfully the observed emission a lambda 5696 and absorption at lambda 8500. The 3p 1 P 0 -3d 1 D transition is found to come into emission at the observed temperatures for both main-sequence and low-gravity objects. The equivalent widths of the emission and absorption lines agree very well with those measured for O stars. In these stars the basic physical mechanism responsible for this phenomenon is the overpopulation of 3d by means of direct recombination and cascades from upper states (with dielectronic recombination taking part in the earliest types) with subsequent cascade to 3p. The 3p state is drained by the two-electron transitions coupling 3p to the 2p 2 ( 1 S, 1 D) states; emission in the 3s 1 S-3p 1 P 0 line is thus prevented. The mechanism of formation of C III is different from that of N III because of dielectronic recombination is not necessary in the former case. The fact that the C III emission line can be produced in a static nonextended atmosphere in radiative equilibrium indicates that the presence of emission lines is not sufficient evidence for the existence of extended atmospheres

  11. Determination of hafnium by atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Yoshida, Isao; Kobayashi, Hiroshi; Ueno, Keihei.

    1977-01-01

    Optimum conditions for atomic absorption spectrophotometric determination of hafnium were investigated by use of a Jarrel-Ash AA-1 instrument which was equipped with a premixed gas burner slotted 50 mm in length and 0.4 mm in width. Absorption of hafnium, which was atomized in an nitrous oxide-acetylene flame, was measured on a resonance line at 307.29 nm. The absorption due to hafnium was enhanced in the presence of ammonium fluoride and iron(III) ion, as shown in Figs. 2 and 3, depending on their concentration. The highest absorption was attained by the addition of (0.15 -- 0.3)M ammonium fluoride, 0.07 M of iron(III) ion and 0.05 M of hydrochloric acid. An excess of the additives decreased the absorption. The presence of zirconium, which caused a significant interference in the ordinary analytical methods, did not affect the absorption due to hafnium, if the zirconium concentration is less than 0.2 M. A standard procedure was proposed; A sample containing a few mg of hafnium was dissolved in a 25-ml volumetric flask, and ammonium fluoride, ferric nitrate and hydrochloric acid were added so that the final concentrations were 0.3, 0.07 and 0.05 M, respectively. Atomic absorption was measured on the aqueous solution in a nitrous oxide-acetylene flame and the hafnium content was calculated from the absorbance. Sensitivity was as high as 12.5 μg of Hf/ml/l% absorption. The present method is especially recommendable to the direct determination of hafnium in samples containing zirconium. (auth.)

  12. Particle-in-a-box model of exciton absorption and electroabsorption in conjugated polymers

    Science.gov (United States)

    Pedersen, Thomas G.

    2000-12-01

    The recently proposed particle-in-a-box model of one-dimensional excitons in conjugated polymers is applied in calculations of optical absorption and electroabsorption spectra. It is demonstrated that for polymers of long conjugation length a superposition of single exciton resonances produces a line shape characterized by a square-root singularity in agreement with experimental spectra near the absorption edge. The effects of finite conjugation length on both absorption and electroabsorption spectra are analyzed.

  13. Calibration-Free Laser-Induced Breakdown Spectroscopy (CF-LIBS) with Standard Reference Line for the Analysis of Stainless Steel.

    Science.gov (United States)

    Fu, Hongbo; Dong, Fengzhong; Wang, Huadong; Jia, Junwei; Ni, Zhibo

    2017-08-01

    In this work, calibration-free laser-induced breakdown spectroscopy (CF-LIBS) is used to analyze a certified stainless steel sample. Due to self-absorption of the spectral lines from the major element Fe and the sparse lines of trace elements, it is usually not easy to construct the Boltzmann plots of all species. A standard reference line method is proposed here to solve this difficulty under the assumption of local thermodynamic equilibrium so that the same temperature value for all elements present into the plasma can be considered. Based on the concentration and rich spectral lines of Fe, the Stark broadening of Fe(I) 381.584 nm and Saha-Boltzmann plots of this element are used to calculate the electron density and the plasma temperature, respectively. In order to determine the plasma temperature accurately, which is seriously affected by self-absorption, a pre-selection procedure for eliminating those spectral lines with strong self-absorption is employed. Then, one spectral line of each element is selected to calculate its corresponding concentration. The results from the standard reference lines with and without self-absorption of Fe are compared. This method allows us to measure trace element content and effectively avoid the adverse effects due to self-absorption.

  14. The Far-Infrared Emission Line and Continuum Spectrum of the Seyfert Galaxy NGC 1068

    Science.gov (United States)

    Spinoglio, Luigi; Smith, Howard A.; Gonzalez-Alfonso, Eduardo; Fisher, Jacqueline

    2005-01-01

    We report on the analysis of the first complete far-infrared spectrum (43-197 microns) of the Seyfert 2 galaxy NGC 1068 as observed with the Long Wavelength Spectrometer (LWS) onboard the Infrared Space Observatory (ISO). In addition to the 7 expected ionic fine structure emission lines, the OH rotational lines at 79, 119 and 163 microns were all detected in emission, which is unique among galaxies with full LWS spectra, where the 119 micron line, where detected, is always in absorption. The observed line intensities were modelled together with IS0 Short Wavelength Spectrometer (SWS) and optical and ultraviolet line intensities from the literature, considering two independent emission components: the AGN component and the starburst component in the circumnuclear ring of approximately 3kpc in size. Using the UV to mid-IR emission line spectrum to constrain the nuclear ionizing continuum, we have confirmed previous results: a canonical power-law ionizing spectrum is a poorer fit than one with a deep absorption trough, while the presence of a big blue bump is ruled out. Based on the instantaneous starburst age of 5 Myr constrained by the Br gamma equivalent width in the starburst ring, and starburst synthesis models of the mid- and far-infrared fine-structure line emission, a low ionization parameter (U=10(exp -3.5)) and low densities (n=100 cm (exp -3)) are derived. Combining the AGN and starburst components, we succeed in modeling the overall UV to far-IR atomic spectrum of SGC 1068, reproducing the line fluxes to within a factor 2.0 on average with a standard deviation of 1.4. The OH 119 micron emission indicates that the line is collisionally excited, and arises in a warm and dense region. The OH emission has been modeled using spherically symmetric, non-local, non-LTE radiative transfer models. The models indicate that the bulk of the emission arises from the nuclear region, although some extended contribution from the starburst is not ruled out. The OH abundance

  15. An automated flow injection system for metal determination by flame atomic absorption spectrometry involving on-line fabric disk sorptive extraction technique.

    Science.gov (United States)

    Anthemidis, A; Kazantzi, V; Samanidou, V; Kabir, A; Furton, K G

    2016-08-15

    A novel flow injection-fabric disk sorptive extraction (FI-FDSE) system was developed for automated determination of trace metals. The platform was based on a minicolumn packed with sol-gel coated fabric media in the form of disks, incorporated into an on-line solid-phase extraction system, coupled with flame atomic absorption spectrometry (FAAS). This configuration provides minor backpressure, resulting in high loading flow rates and shorter analytical cycles. The potentials of this technique were demonstrated for trace lead and cadmium determination in environmental water samples. The applicability of different sol-gel coated FPSE media was investigated. The on-line formed complex of metal with ammonium pyrrolidine dithiocarbamate (APDC) was retained onto the fabric surface and methyl isobutyl ketone (MIBK) was used to elute the analytes prior to atomization. For 90s preconcentration time, enrichment factors of 140 and 38 and detection limits (3σ) of 1.8 and 0.4μgL(-1) were achieved for lead and cadmium determination, respectively, with a sampling frequency of 30h(-1). The accuracy of the proposed method was estimated by analyzing standard reference materials and spiked water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Contamination of the Th II line and the age of the Galaxy

    International Nuclear Information System (INIS)

    Lawler, J.E.; Whaling, W.; Grevesse, N.

    1990-01-01

    The age of the Galaxy may be estimated from observations of the ratio of stellar abundances of thorium, which has only one long-lived isotope with a half-life comparable to the suspected age of the Galaxy, and neodymium, a stable element. The Th/Nd abundance ratio in a sample of G-dwarf stars of different ages was derived from the intensities of one Th II and one Nd II absorption line, and indicated a rather young galactic age of 9.6 Gyr. But the Th II line is blended with a Co I line. Here we determine the transition probability of the Co I line by combining radiative lifetime and branching-ratio measurements. We show that the Co I contribution cannot be neglected in deriving Th/Nd ratios. By comparing our results with predictions based on models of galactic chemical evolution, we suggest a revised age of the Galaxy of 15-20 Gyr. (author)

  17. Absorption lineshape of FA centers in alkali halides

    International Nuclear Information System (INIS)

    Baldacchini, G.; Giovenale, E.; De Matteis, F.; Scacco, A.; Somma, F.; Grassano, U.M.

    1988-01-01

    The line shape of the absorption bands of F A centers in alkali halides have been studied for the first time. The new method used for this investigation is based on the determination of the overlap between the F A1 and F A2 bands from luminescence measurements. The experimental results have been compared with calculated values deduced from the theoretical F A bands of different shapes. For both F A (I) centers in KCl:Na + and F A (II) centers in KCl:Li + and RbCl:Li + the absorption lineshape at low temperature is much closer to a sum of two Lorentzian curves than that of two Gaussian or Poissonian bands. This results shows an unexpected difference with the F centers, whose absorption lineshape is known to be Poissonian at the same temperatures

  18. Determination of cadmium in aluminium by atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Batistoni, D.A.; Erlijman, L.H.

    1978-12-01

    A direct method for the determination of cadmium in elemental aluminium is described. Metal samples are dissolved in diluted hydrochloric acid and cadmium is determined by atomic absorption spectrometry in an air-acetylene flame. Interference by non-specific absorption observed at the analytical wavelength incorrected for by means of a non-absorbing line emitted by the hollow-cathode lamp. Relatively large amounts of arsenic do not interfere. The minimun determinable concentration of cadmium for this procedure is 2-3 ppm, expressed on aluminium basis. (author) [es

  19. Two-dimensional thermometry by using neutron resonance absorption spectrometer DOG

    International Nuclear Information System (INIS)

    Kamiyama, T.; Noda, H.; Kiyanagi, Y.; Ikeda, S.

    2001-01-01

    We applied the neutron resonance absorption spectroscopy to thermometry of a bulk object. The measurement was done by using the neutron resonance absorption spectrometer, DOG, installed at KENS, High Energy Accelerator Research Organization Neutron Source, which enables us to investigate effective temperature of a particular element by analyzing line width of resonance absorption spectrum. The effective temperature becomes consistence with the sample temperature above room temperature. For the analysis we applied the computed tomography method to reconstruct the temperature distribution on the object cross section. The results and the calculated distribution by the heat conducting equation are well agreed on the temperature difference inside the object. (author)

  20. Identifying the perfect absorption of metamaterial absorbers

    Science.gov (United States)

    Duan, G.; Schalch, J.; Zhao, X.; Zhang, J.; Averitt, R. D.; Zhang, X.

    2018-01-01

    We present a detailed analysis of the conditions that result in unity absorption in metamaterial absorbers to guide the design and optimization of this important class of functional electromagnetic composites. Multilayer absorbers consisting of a metamaterial layer, dielectric spacer, and ground plane are specifically considered. Using interference theory, the dielectric spacer thickness and resonant frequency for unity absorption can be numerically determined from the functional dependence of the relative phase shift of the total reflection. Further, using transmission line theory in combination with interference theory we obtain analytical expressions for the unity absorption resonance frequency and corresponding spacer layer thickness in terms of the bare resonant frequency of the metamaterial layer and metallic and dielectric losses within the absorber structure. These simple expressions reveal a redshift of the unity absorption frequency with increasing loss that, in turn, necessitates an increase in the thickness of the dielectric spacer. The results of our analysis are experimentally confirmed by performing reflection-based terahertz time-domain spectroscopy on fabricated absorber structures covering a range of dielectric spacer thicknesses with careful control of the loss accomplished through water absorption in a semiporous polyimide dielectric spacer. Our findings can be widely applied to guide the design and optimization of the metamaterial absorbers and sensors.

  1. Doppler broadening and its contribution to Compton energy-absorption cross sections: An analysis of the Compton component in terms of mass-energy absorption coefficient

    International Nuclear Information System (INIS)

    Rao, D.V.; Takeda, T.; Itai, Y.; Akatsuka, T.; Cesareo, R.; Brunetti, A.; Gigante, G.E.

    2002-01-01

    Compton energy absorption cross sections are calculated using the formulas based on a relativistic impulse approximation to assess the contribution of Doppler broadening and to examine the Compton profile literature and explore what, if any, effect our knowledge of this line broadening has on the Compton component in terms of mass-energy absorption coefficient. Compton energy-absorption cross sections are evaluated for all elements, Z=1-100, and for photon energies 1 keV-100 MeV. Using these cross sections, the Compton component of the mass-energy absorption coefficient is derived in the energy region from 1 keV to 1 MeV for all the elements Z=1-100. The electron momentum prior to the scattering event should cause a Doppler broadening of the Compton line. The momentum resolution function is evaluated in terms of incident and scattered photon energy and scattering angle. The overall momentum resolution of each contribution is estimated for x-ray and γ-ray energies of experimental interest in the angular region 1 deg. -180 deg. . Also estimated is the Compton broadening using nonrelativistic formula in the angular region 1 deg. -180 deg., for 17.44, 22.1, 58.83, and 60 keV photons for a few elements (H, C, N, O, P, S, K, and Ca) of biological importance

  2. Doppler Broadening and its Contribution to Compton Energy-Absorption Cross Sections: An Analysis of the Compton Component in Terms of Mass-Energy Absorption Coefficient

    Science.gov (United States)

    Rao, D. V.; Takeda, T.; Itai, Y.; Akatsuka, T.; Cesareo, R.; Brunetti, A.; Gigante, G. E.

    2002-09-01

    Compton energy absorption cross sections are calculated using the formulas based on a relativistic impulse approximation to assess the contribution of Doppler broadening and to examine the Compton profile literature and explore what, if any, effect our knowledge of this line broadening has on the Compton component in terms of mass-energy absorption coefficient. Compton energy-absorption cross sections are evaluated for all elements, Z=1-100, and for photon energies 1 keV-100 MeV. Using these cross sections, the Compton component of the mass-energy absorption coefficient is derived in the energy region from 1 keV to 1 MeV for all the elements Z=1-100. The electron momentum prior to the scattering event should cause a Doppler broadening of the Compton line. The momentum resolution function is evaluated in terms of incident and scattered photon energy and scattering angle. The overall momentum resolution of each contribution is estimated for x-ray and γ-ray energies of experimental interest in the angular region 1°-180°. Also estimated is the Compton broadening using nonrelativistic formula in the angular region 1°-180°, for 17.44, 22.1, 58.83, and 60 keV photons for a few elements (H, C, N, O, P, S, K, and Ca) of biological importance.

  3. EUV lines observed with EIS/Hinode in a solar prominence

    Science.gov (United States)

    Labrosse, N.; Schmieder, B.; Heinzel, P.; Watanabe, T.

    2011-07-01

    Context. During a multi-wavelength observation campaign with Hinode and ground-based instruments, a solar prominence was observed for three consecutive days as it crossed the western limb of the Sun in April 2007. Aims: We report on observations obtained on 26 April 2007 using EIS (Extreme ultraviolet Imaging Spectrometer) on Hinode. They are analysed to provide a qualitative diagnostic of the plasma in different parts of the prominence. Methods: After correcting for instrumental effects, the rasters at different wavelengths are presented. Several regions within the same prominence are identified for further analysis. Selected profiles for lines with formation temperatures between log (T) = 4.7 and log (T) = 6.3, as well as their integrated intensities, are given. The profiles of coronal, transition region, and He ii lines are discussed. We pay special attention to the He ii line, which is blended with coronal lines. Results: Some quantitative results are obtained by analysing the line profiles. They confirm that depression in EUV lines can be interpreted in terms of two mechanisms: absorption of coronal radiation by the hydrogen and neutral helium resonance continua, and emissivity blocking. We present estimates of the He ii line integrated intensity in different parts of the prominence according to different scenarios for the relative contribution of absorption and emissivity blocking to the coronal lines blended with the He ii line. We estimate the contribution of the He ii 256.32 Å line to the He ii raster image to vary between ~44% and 70% of the raster's total intensity in the prominence according to the different models used to take into account the blending coronal lines. The inferred integrated intensities of the He ii 256 Å line are consistent with the theoretical intensities obtained with previous 1D non-LTE radiative transfer calculations, yielding a preliminary estimate of the central temperature of 8700 K, a central pressure of 0.33 dyn cm-2, and a

  4. Absorption-line detections of 10{sup 5}-10{sup 6} K gas in spiral-rich groups of galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Stocke, John T.; Keeney, Brian A.; Danforth, Charles W.; Syphers, David; Yamamoto, H.; Shull, J. Michael; Green, James C.; Froning, Cynthia [Center for Astrophysics and Space Astronomy, Department of Astrophysical and Planetary Sciences, University of Colorado, 389 UCB, Boulder, CO 80309 (United States); Savage, Blair D.; Wakker, Bart; Kim, Tae-Sun [Department of Astronomy, University of Wisconsin, Madison, WI 53706 (United States); Ryan-Weber, Emma V.; Kacprzak, Glenn G., E-mail: john.stocke@colorado.edu [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, VIC 3122 (Australia)

    2014-08-20

    Using the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope, the COS Science Team has conducted a high signal-to-noise survey of 14 bright QSOs. In a previous paper, these far-UV spectra were used to discover 14 'warm' (T ≥ 10{sup 5} K) absorbers using a combination of broad Lyα and broad O VI absorptions. A reanalysis of a few of this new class of absorbers using slightly relaxed fitting criteria finds as many as 20 warm absorbers could be present in this sample. A shallow, wide spectroscopic galaxy redshift survey has been conducted around these sight lines to investigate the warm absorber environment, which is found to be spiral-rich groups or cluster outskirts with radial velocity dispersions σ = 250-750 km s{sup –1}. While 2σ evidence is presented favoring the hypothesis that these absorptions are associated with the galaxy groups and not with the individual, nearest galaxies, this evidence has considerable systematic uncertainties and is based on a small sample size so it is not entirely conclusive. If the associations are with galaxy groups, the observed frequency of warm absorbers (dN/dz = 3.5-5 per unit redshift) requires them to be very extended as an ensemble on the sky (∼1 Mpc in radius at high covering factor). Most likely these warm absorbers are interface gas clouds whose presence implies the existence of a hotter (T ∼ 10{sup 6.5} K), diffuse, and probably very massive (>10{sup 11} M {sub ☉}) intra-group medium which has yet to be detected directly.

  5. Optical absorption and electron spin resonance in natural, irradiated and heated spodumene

    International Nuclear Information System (INIS)

    Ito, A.S.; Isotani, S.

    1983-09-01

    Heat treatment and X and γ-Rays irradiation of lylac and colorless natural spodumene, LiAlSi 2 O 6 , have been studied. Irradiation produces a color change, from lylac or colorless to green. Irradiated samples heated at 200 0 C turn lylac and bleach at 400 0 C. Optical absorption spectra were decomposed into gaussian line shape bands and it is observed that green and lylac centers are simultaneously created by irradiation. These centers are independent from each other. Optical absorption, EPR and X-Ray fluorescence results show the spectra of impurities, responsible by the presence of the created centers and indicated Mn participation in the process of centers creation and destruction. Decay Kinetics of green and lylac centers have been studied and it is observed that simple Kinetic models do not apply to these cases. An empirical fit allowed the calculation of activation energies of the lylac and green centers decays. Discussions about the present results led us to propose a new model where the green and lylac centers are due to Mn 3+ ions in two different Al 3+ sites, whose absorption are intensified by the interaction with an electron trapped in a neighbour oxygen. (Author) [pt

  6. Correlation between oral drug absorption in humans and apparent drug permeability coefficients in human intestinal epithelial (Caco-2) cells

    International Nuclear Information System (INIS)

    Artursson, P.; Karlsson, J.

    1991-01-01

    Monolayers of a well differentiated human intestinal epithelial cell line, Caco-2, were used as a model to study passive drug absorption across the intestinal epithelium. Absorption rate constants (expressed as apparent permeability coefficients) were determined for 20 drugs and peptides with different structural properties. The permeability coefficients ranged from approximately 5 x 10 - 8 to 5 x 10 - 5 cm/s. A good correlation was obtained between data on oral absorption in humans and the results in the Caco-2 model. Drugs that are completely absorbed in humans had permeability coefficients greater than 1 x 10 - 6 cm/s. Drugs that are absorbed to greater than 1% but less than 100% had permeability coefficients of 0.1-1.0 x 10 - 6 cm/s while drugs and peptides that are absorbed to less than 1% had permeability coefficients of less than or equal to 1 x 10 - 7 cm/s. The results indicate that Caco-2 monolayers can be used as a model for studies on intestinal drug absorption

  7. Effects of the Absorption Behaviour of ZnO Nanoparticles on Cytotoxicity Measurements

    Directory of Open Access Journals (Sweden)

    Nigar Najim

    2014-01-01

    Full Text Available ZnO absorbs certain wavelengths of light and this behavior is more pronounced for nanoparticles of ZnO. As many toxicity measurements rely on measuring light transmission in cell lines, it is essential to determine how far this light absorption influences experimental toxicity measurements. The main objective was to study the ZnO absorption and how this influenced the cytotoxicity measurements. The cytotoxicity of differently sized ZnO nanoparticles in normal and cancer cell lines derived from lung tissue (Hs888Lu, neuron-phenotypic cells (SH-SY5Y, neuroblastoma (SH-SY5Y, human histiocytic lymphoma (U937, and lung cancer (A549 was investigated. Our results demonstrate that the presence of ZnO affected the cytotoxicity measurements due to the absorption characteristic of ZnO nanoparticles. The data revealed that the ZnO nanoparticles with an average particle size of around 85.7 nm and 190 nm showed cytotoxicity towards U937, SH-SY5Y, differentiated SH-SY5Y, and Hs888Lu cell lines. No effect on the A549 cells was observed. It was also found that the cytotoxicity of ZnO was particle size, concentration, and time dependent. These studies are the first to quantify the influence of ZnO nanoparticles on cytotoxicity assays. Corrections for absorption effects were carried out which gave an accurate estimation of the concentrations that produce the cytotoxic effects.

  8. Study of Material Moisture Measurement Method and Instrument by the Combination of Fast Neutron Absorption and γ Absorption

    International Nuclear Information System (INIS)

    Hou Chaoqin; Gong Yalin; Zhang Wei; Shang Qingmin; Li Yanfeng; Gou Qiangyuan; Yin Deyou

    2010-01-01

    To solve the problem of on-line sinter moisture measurement in the iron making plant, we developed material moisture measurement method and instrument by the combination of fast neutron absorption and y-absorption. It overcomes the present existed problems of other moisture meters for the sinter. Compare with microwave moisture meter, the measurement dose not affected by conductance and magnetism of material; to infrared moisture meter, the measurement result dose not influenced by colour and light-reflect performance of material surface, dose not influenced by changes of material kind; to slow neutron scatter moisture meter, the measurement dose not affected by density of material and thickness of hopper wall; to the moisture measurement meter which combined by slow neutron penetrate through and y-absorption, there are definite math model and good linear relation between the measurement values, and the measurement dose not affected by material thickness, changes of material form and component. (authors)

  9. Iron absorption in relation to iron status

    International Nuclear Information System (INIS)

    Magnusson, B.; Bjoern-Rasmussen, E.; Hallberg, L.; Rossander, L.

    1981-01-01

    The absorption from a 3 mg dose of ferrous iron was measured in 250 male subjects. The absorption was related to the log concentration of serum ferritin in 186 subjects of whom 99 were regular blood donors (r= -0.76), and to bone marrow haemosiderin grading in 52 subjects with varying iron status. The purpose was to try and establish a percentage absorption from such a dose that is representative of subjects who are borderline iron deficient. This information is necessary for food iron absorption studies in order (1) to calculate the absorption of iron from the diet at a given iron status and (2) compare the absorption of iron from different meals studied in different groups of subjects by different investigarors. The results suggest that an absorption of about 40% of a 3 mg reference dose of ferrous iron is given in a fasting state, roughly corresponds to the absorption in borderline-iron-deficient subjects. The results indicate that this 40% absorption value corresponds to a serum ferritin level of 30 μg/l and that food iron absorption in a group of subjects should be expressed preferably as the absorption corresponding to a reference-dose absorption of 45%, or possibly a serum ferritin level of 30 μg/l. (author)

  10. Geometrical interpretation of optical absorption

    Energy Technology Data Exchange (ETDEWEB)

    Monzon, J. J.; Barriuso, A. G.; Sanchez-Soto, L. L. [Departamento de Optica, Facultad de Fisica, Universidad Complutense, E-28040 Madrid (Spain); Montesinos-Amilibia, J. M. [Departamento de Geometria y Topologia, Facultad de Matematicas, Universidad Complutense, E-28040 Madrid (Spain)

    2011-08-15

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

  11. C IV LINE-WIDTH ANOMALIES

    DEFF Research Database (Denmark)

    Denney, Kelly Dianne; Pogge, R.W.; Assef, R.J.

    2013-01-01

    Comparison of six high-redshift quasar spectra obtained with the Large Binocular Telescope with previous observations from the Sloan Digital Sky Survey shows that failure to correctly identify absorption and other problems with accurate characterization of the CIV emission line profile in low S/N...

  12. 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

  13. Rapidly variable relatvistic absorption

    Science.gov (United States)

    Parker, M.; Pinto, C.; Fabian, A.; Lohfink, A.; Buisson, D.; Alston, W.; Jiang, J.

    2017-10-01

    I will present results from the 1.5Ms XMM-Newton observing campaign on the most X-ray variable AGN, IRAS 13224-3809. We find a series of nine absorption lines with a velocity of 0.24c from an ultra-fast outflow. For the first time, we are able to see extremely rapid variability of the UFO features, and can link this to the X-ray variability from the inner accretion disk. We find a clear flux dependence of the outflow features, suggesting that the wind is ionized by increasing X-ray emission.

  14. The steady state solutions of radiatively driven stellar winds for a non-Sobolev, pure absorption model

    International Nuclear Information System (INIS)

    Poe, C.H.; Owocki, S.P.; Castor, J.I.

    1990-01-01

    The steady state solution topology for absorption line-driven flows is investigated for the condition that the Sobolev approximation is not used to compute the line force. The solution topology near the sonic point is of the nodal type with two positive slope solutions. The shallower of these slopes applies to reasonable lower boundary conditions and realistic ion thermal speed v(th) and to the Sobolev limit of zero of the usual Castor, Abbott, and Klein model. At finite v(th), this solution consists of a family of very similar solutions converging on the sonic point. It is concluded that a non-Sobolev, absorption line-driven flow with a realistic values of v(th) has no uniquely defined steady state. To the extent that a pure absorption model of the outflow of stellar winds is applicable, radiatively driven winds should be intrinsically variable. 34 refs

  15. Dynamic light absorption of biomass-burning organic carbon photochemically aged under natural sunlight

    Science.gov (United States)

    Zhong, M.; Jang, M.

    2014-02-01

    Wood-burning aerosol produced under smoldering conditions was photochemically aged with different relative humidity (RH) and NOx conditions using a 104 m3 dual outdoor chamber under natural sunlight. Light absorption of organic carbon (OC) was measured over the course of photooxidation using a UV-visible spectrometer connected to an integrating sphere. At high RH, the color decayed rapidly. NOx slightly prolonged the color of wood smoke, suggesting that NOx promotes the formation of chromophores via secondary processes. Overall, the mass absorption cross section (integrated between 280 and 600 nm) of OC increased by 11-54% (except high RH) in the morning and then gradually decreased by 19-68% in the afternoon. This dynamic change in light absorption of wood-burning OC can be explained by two mechanisms: chromophore formation and sunlight bleaching. To investigate the effect of chemical transformation on light absorption, wood smoke particles were characterized using various spectrometers. The intensity of fluorescence, which is mainly related to polycyclic aromatic hydrocarbons (PAHs), rapidly decreased with time, indicating the potential bleaching of PAHs. A decline of levoglucosan concentrations evinced the change of primary organic aerosol with time. The aerosol water content measured by Fourier transform infrared spectroscopy showed that wood-burning aerosol became less hygroscopic as photooxidation proceeded. A similar trend in light absorption changes has been observed in ambient smoke aerosol originating from the 2012 County Line wildfire in Florida. We conclude that the biomass-burning OC becomes less light absorbing after 8-9 h sunlight exposure compared to fresh wood-burning OC.

  16. Dynamic light absorption of biomass burning organic carbon photochemically aged under natural sunlight

    Science.gov (United States)

    Zhong, M.; Jang, M.

    2013-08-01

    Wood burning aerosol produced under smoldering conditions was photochemically aged with different relative humidity (RH) and NOx conditions using a 104 m3 dual outdoor chamber under natural sunlight. Light absorption of organic carbon (OC) was measured over the course of photooxidation using a UV-visible spectrometer connected to an integrating sphere. At high RH, the color decayed rapidly. NOx slightly prolonged the color of wood smoke, suggesting that NOx promotes the formation of chromophores via secondary processes. Overall, the mass absorption cross-section (integrated between 280 nm and 600 nm) of OC increased by 11-54% (except high RH) in the morning and then gradually decreased by 19-68% in the afternoon. This dynamic change in light absorption of wood burning OC can be explained by two mechanisms: chromophore formation and sunlight bleaching. To investigate the effect of chemical transformation on light absorption, wood smoke particles were characterized using various spectrometers. The intensity of fluorescence, which is mainly related to polycyclic aromatic hydrocarbons (PAHs), rapidly decreased with time indicating the potential bleaching of PAHs. A decline of levoglucosan concentrations evinced the change of POA with time. The aerosol water content measured by Fourier transform infrared spectroscopy showed that wood burning aerosol became less hygroscopic as photooxidation proceeded. A similar trend in light absorption changes has been observed in ambient smoke aerosol originating from the 2012 County Line Wildfire in Florida. We conclude that the biomass burning OC becomes less light absorbing after 8-9 h sunlight exposure compared to fresh wood burning OC.

  17. Thermal effects on the cyclotron line formation process in X-ray pulsars

    International Nuclear Information System (INIS)

    Kirk, J.G.; Meszaros, P.

    1980-01-01

    We derive expressions for the scattering and absorption cross sections in a hot plasma including the effects of vacuum polarisation. These expressions are then used in a radiative transfer calculation for frequencies in the neighbourhood of the cyclotron resonance using a simplified model atmosphere for accreting magnetised X-ray pulsars. Cyclotron emission and absorption line model fits are discussed, the conclusion being that an emission line interpretation appears at this stage more likely. (orig.)

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

    Science.gov (United States)

    Parker, Ron; Carr, Zak; MacLean, Mathew; Dufrene, Aaron; Mehta, Manish

    2016-01-01

    This paper describes the Tunable Diode Laser Absorption Spectroscopy (TDLAS) measurement of several water transitions that were interrogated during a hot-fire testing of the Space Launch Systems (SLS) sub-scale vehicle installed in LENS II. The temperature of the recirculating gas flow over the base plate was found to increase with altitude and is consistent with CFD results. It was also observed that the gas above the base plate has significant velocity along the optical path of the sensor at the higher altitudes. The line-by-line analysis of the H2O absorption features must include the effects of the Doppler shift phenomena particularly at high altitude. The TDLAS experimental measurements and the analysis procedure which incorporates the velocity dependent flow will be described.

  19. Optoacoustic measurements of water vapor absorption at selected CO laser wavelengths in the 5-micron region

    Science.gov (United States)

    Menzies, R. T.; Shumate, M. S.

    1976-01-01

    Measurements of water vapor absorption were taken with a resonant optoacoustical detector (cylindrical pyrex detector, two BaF2 windows fitted into end plates at slight tilt to suppress Fabry-Perot resonances), for lack of confidence in existing spectral tabular data for the 5-7 micron region, as line shapes in the wing regions of water vapor lines are difficult to characterize. The measurements are required for air pollution studies using a CO laser, to find the differential absorption at the wavelengths in question due to atmospheric constituents other than water vapor. The design and performance of the optoacoustical detector are presented. Effects of absorption by ambient NO are considered, and the fixed-frequency discretely tunable CO laser is found suitable for monitoring urban NO concentrations in a fairly dry climate, using the water vapor absorption data obtained in the study.

  20. Investigation of chemical modifiers for phosphorus in a graphite furnace using high-resolution continuum source atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Lepri, Fabio G.; Dessuy, Morgana B.; Vale, Maria Goreti R.; Borges, Daniel L.G.; Welz, Bernhard; Heitmann, Uwe

    2006-01-01

    Phosphorus is not one of the elements that are typically determined by atomic absorption spectrometry, but this technique nevertheless offers several advantages that make it attractive, such as the relatively great freedom from interferences. As the main resonance lines for phosphorus are in the vacuum-ultraviolet, inaccessible by conventional atomic absorption spectrometry equipment, L'vov and Khartsyzov proposed to use the non-resonance doublet at 213.5 / 213.6 nm. Later it turned out that with conventional equipment it is necessary to use a chemical modifier in order to get reasonable sensitivity, and lanthanum was the first one suggested for that purpose. In the following years more than 30 modifiers have been proposed for the determination of this element, and there is no consensus about the best one. In this work high-resolution continuum source atomic absorption spectrometry has been used to investigate the determination of phosphorus without a modifier and with the addition of selected modifiers of very different nature, including the originally recommended lanthanum modifier, several palladium-based modifiers and sodium fluoride. As high-resolution continuum source atomic absorption spectrometry is revealing the spectral environment of the analytical line at high resolution, it became obvious that without the addition of a modifier essentially no atomic phosphorus is formed, even at 2700 deg. C . The absorption measured with line source atomic absorption spectrometry in this case is due to the PO molecule, the spectrum of which is overlapping with the atomic line. Palladium, with or without the addition of calcium or ascorbic acid, was found to be the only modifier to produce almost exclusively atomic phosphorus. Lanthanum and particularly sodium fluoride produced a mixture of P and PO, depending on the atomization temperature. This fact can explain at least some of the discrepancies found in the literature and some of the phenomena observed in the

  1. Determination of trace metal ions via on-line separation and preconcentration by means of chelating Sepharose beads in a sequential injection lab-on-valve (SI-LOV) system coupled to electrothermal atomic absorption spectrometric detection

    DEFF Research Database (Denmark)

    Long, Xiangbao; Hansen, Elo Harald; Miró, Manuel

    2005-01-01

    The analytical performance of an on-line sequential injection lab-on-valve (SI-LOV) system using chelating Sepharose beads as sorbent material for the determination of ultra trace levels of Cd(II), Pb(II) and Ni(II) by electrothermal atomic absorption spectrometry (ETAAS) is described and discussed...

  2. MNC Knowledge Transfer, Subsidiary Absorptive Capacity and HRM

    DEFF Research Database (Denmark)

    Minbaeva, Dana; Pedersen, Torben; Björkman, Ingmar

    2014-01-01

    Based on a sample of 169 subsidiaries of multinational corporations (MNCs) operating in the USA, Russia, and Finland, this paper investigates the relationship between MNC subsidiary HRM practices, absorptive capacity and knowledge transfer. First, we examine the relationship between the application...... of specific HRM practices and the level of the absorptive capacity. Second, we suggest that absorptive capacity should be conceptualized as being comprised of both employees’ ability and motivation. Further, results indicate that both ability and motivation (absorptive capacity) are needed to facilitate...

  3. DETECTION OF CA II ABSORPTION BY A HIGH-VELOCITY CLOUD IN THE DIRECTION OF THE QUASAR PKS 0837-120

    NARCIS (Netherlands)

    ROBERTSON, JG; SCHWARZ, UJ; VANWOERDEN, H; MURRAY, JD; MORTON, DC; HULSBOSCH, ANM

    1991-01-01

    We present optical absorption spectroscopy of the Ca II K and H lines along the sight line to the quasar PKS 0837-120, which lies in the direction of a high-velocity cloud (HVC) detected in H I 21-cm emission at V(LSR) = + 105 km s-1. Our data show Ca II absorption due to the HVC as well as a lower

  4. Suzaku and XMM-Newton observations of the North Polar Spur: Charge exchange or ISM absorption?

    Science.gov (United States)

    Gu, Liyi; Mao, Junjie; Costantini, Elisa; Kaastra, Jelle

    2016-10-01

    By revisiting the Suzaku and XMM-Newton data of the North Polar Spur, we discovered that the spectra are inconsistent with the traditional model consisting of pure thermal emission and neutral absorption. The most prominent discrepancies are the enhanced O vii and Ne ix forbidden-to-resonance ratios, and a high O viii Lyβ line relative to other Lyman series. A collisionally ionized absorption model can naturally explain both features, while a charge exchange component can only account for the former. By including the additional ionized absorption, the plasma in the North Polar Spur can be described by a single-phase collisional ionization equilibrium (CIE) component with a temperature of 0.25 keV, and nitrogen, oxygen, neon, magnesium, and iron abundances of 0.4-0.8 solar. The abundance pattern of the North Polar Spur is well in line with those of the Galactic halo stars. The high nitrogen-to-oxygen ratio reported in previous studies can be migrated to the large transmission of the O viii Lyα line. The ionized absorber is characterized by a balance temperature of 0.17-0.20 keV and a column density of 3-5 × 1019 cm-2. Based on the derived abundances and absorption, we speculate that the North Polar Spur is a structure in the Galactic halo, so that the emission is mostly absorbed by the Galactic interstellar medium in the line of sight.

  5. Can the snowline be used as an indicator of the equilibrium line and mass balance for glaciers in the outer tropics ?

    OpenAIRE

    Rabatel, A.; Bermejo, A.; Loarte, E.; Soruco, A.; Gomez, J.; Leonardini, G.; Vincent, C.; Sicart, Jean-Emmanuel

    2012-01-01

    Because the glacier snowline is easy to identify on optical satellite images and because in certain conditions it can be used as an indicator of the equilibrium line, it may be a relevant parameter for the study of the relationships between climate and glaciers. Although several studies have shown that the snowline altitude (SLA) at the end of the hydrological year is a good indicator of the equilibrium-line altitude (ELA) for mid-latitude glaciers, such a relationship remains conjectural for...

  6. 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.

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

    Science.gov (United States)

    White, Logan; Gamba, Mirko

    2018-04-01

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

  8. 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

  9. Light absorption in thin quantizing semiconductor wires with non-parabolic law of dispersion of charge carriers

    International Nuclear Information System (INIS)

    Djotian, A.P.; Kazarian, E.M.; Karakashinian, Y.V.

    1993-01-01

    Interband absorption of light in a quantizing wire with non-parabolic dispersion law of charge carries, as well as energy spectrum and state densities are studied. The effect of Coulomb interaction between particles on the spectral curve of interband absorption is considered. Non-parabolic dispersion law of charge carries leads to an essential displacement of absorption line to ground state of one-dimensional exciton. 7 refs

  10. $J/\\psi$ Absorption in Heavy Ion Collisions

    CERN Document Server

    Maiani, Luciano; Polosa, Antonio; Riquer, V

    2004-01-01

    We present a new calculation of the pi-J/psi dissociation cross sections within the Constituent Quark-Meson Model recently introduced. To discuss the absorption of J/psi in heavy-ion collisions, we assume the J/psi to be produced inside a thermalized pion gas, as discussed by Bjorken, and introduce the corrections due to absorption by nuclear matter as well. We fit the absorption length of the J/psi to the data obtained at the CERN SPS by the NA50 Collaboration for Pb-Pb collisions. Collisions of lower centrality allow us to determine the temperature and the energy density of the pion gas. For both these quantities we find values close to those indicated by lattice gauge calculations for the transition to a quark-gluon plasma. A simple extrapolation to more central collisions, which takes into account the increase of the energy deposited due to the increased nucleon flux, fails to reproduce the break in J/psi absorption indicated by NA50, thus lending support to the idea that an unconfined quark-gluon phase m...

  11. Effective photons in weakly absorptive dielectric media and the Beer–Lambert–Bouguer law

    International Nuclear Information System (INIS)

    Judge, A C; Brownless, J S; Martijn de Sterke, C; Bhat, N A R; Sipe, J E; Steel, M J

    2014-01-01

    We derive effective photon modes that facilitate an intuitive and convenient picture of photon dynamics in a structured Kramers–Kronig dielectric in the limit of weak absorption. Each mode is associated with a mode field distribution that includes the effects of both material and structural dispersion, and an effective line-width that determines the temporal decay rate of the photon. These results are then applied to obtain an expression for the Beer–Lambert–Bouguer law absorption coefficient for unidirectional propagation in structured media consisting of dispersive, weakly absorptive dielectric materials

  12. Measurement of the population densities in Gd atomic vapor using diode laser absorption spectroscopy in UV transitions

    International Nuclear Information System (INIS)

    Kwon, Duck Hee; Jung, E. C.; Ko, Kwang Hoon; Kim, Tack Soo

    2003-01-01

    We report on the ultraviolet laser absorption spectroscopy of atomic Gd at 394-554 nm where two transition lines are place very closely by using a frequency-doubled beam of external-cavity diode laser (ECDL). One is from 999.121 to 26337.071 cm -1 and the other from 0 to 25337.755 cm -1 . If two transition lines are placed closely within a continuous fine tuning range, the real-time measurement of the atomic excitation temperature is possible without any significant time consumption because at least two transition lines originating from different low-lying energy levels need to be investigated for the Boltzmann-plot. Since the spectral difference between the two transitions is only about 0.195 cm -1 (5.85 GHz), it is possible to record both the absorption spectra simultaneously as shown in Fig. 1. But the transition probabilities (or oscillator strengths) of these lines have not been measured accurately yet to the best of our knowledge. We report on the newly measured transition probabilities by analyzing their absorption spectra at known vapor density conditions. The simultaneous measurement of the atomic excitation temperature and the vapor density demonstrated. In addition we present another ultraviolet laser absorption spectroscopy of atomic Gd at 403.540 nm by means of a commercial blue diode laser and investigate the characteristics of the blue diode laser as well.

  13. Color centers in KCN: ferro-elastic alignment and free optical absorption of phonons

    International Nuclear Information System (INIS)

    Grillo, M.L.N.

    1983-01-01

    Some color centers in KCN pure and KCL or KOH doped are studied. The used tecniques for detection of these color centers were optical absorption and electron paramagnetic resonance (EPR). To obtain this color centers crystals were always exposed to X-rays. With an optical absorption technique, one color center was analysed after X-ray irradiation followed by a suitable photochemical process. Throught the EPR technique the F center and three other centers produced by radiation damage were observed through several KCN solid phases. As in the orthorhombic and ferroelastic phase (temperatures between 168K and 83K), the crystals of KCN present one multidomain structure responsable for strong light scattering on the optical absorption spectra and EPR spectra that does not present the resolved lines formed above 168K, one system of aligned domains was obtained through mechanical stress built specifically to be capable of reducing the number of distinct domain, and this allowed us to observe of partially resolved EPR lines. (Auhtor) [pt

  14. Modified mesoporous silica materials for on-line separation and preconcentration of hexavalent chromium using a microcolumn coupled with flame atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Wang Zheng, E-mail: wangzheng@mail.sic.ac.cn [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Fang Dongmei; Li Qing [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); East China University of Science and Technology, Shanghai 200237 (China); Zhang Lingxia; Qian Rong; Zhu Yan; Qu Haiyun [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Du Yiping [East China University of Science and Technology, Shanghai 200237 (China)

    2012-05-06

    Highlights: Black-Right-Pointing-Pointer A modified SBA-15 mesoporous silica material (NH{sub 2}-SBA-15) was synthesized as sorbent. Black-Right-Pointing-Pointer The material was used for the first time in a flow injection on-line solid phase extraction (SPE) coupled with flame atomic absorption spectrometry (FAAS) to detect trace Cr (VI). Black-Right-Pointing-Pointer The NH{sub 2}-SBA-15 enables retain Cr (VI) with an enrichment factor of 44. Black-Right-Pointing-Pointer The micro-column of NH{sub 2}-SBA-15 underwent more than 100 adsorption/desorption cycles. - Abstract: A modified SBA-15 mesoporous silica material NH{sub 2}-SBA-15 was synthesized successfully by grafting {gamma}-aminopropyl-triethoxysilane. The material was characterized using transmission electron microscopy (TEM) and Fourier transform infrared/Raman (FT-IR/Raman) spectroscopy, and used for the first time in a flow injection on-line solid phase extraction (SPE) coupled with flame atomic absorption spectrometry (FAAS) to detect trace Cr (VI). Effective sorption of Cr (VI) was achieved at pH 2.0 with no interference from Cr (III) and other ions and 0.5 mol L{sup -1} NH{sub 3}{center_dot}H{sub 2}O solution was found optimal for the complete elution of Cr (VI). An enrichment factor of 44 and was achieved under optimized experimental conditions at a sample loading of 2.0 mL min{sup -1} sample loading (300 s) and an elution flow rate of 2.0 mL min{sup -1} (24 s). The precision of the 11 replicate Cr (VI) measurements was 2.1% at the 100 {mu}g L{sup -1} level with a detection limit of 0.2 {mu}g L{sup -1} (3 s, n = 10) using the FAAS. The developed method was successfully applied to trace chromium determination in waste water. The accuracy was validated using a certified reference material of riverine water (GBW08607).

  15. Simulation of Near-Edge X-ray Absorption Fine Structure with Time-Dependent Equation-of-Motion Coupled-Cluster Theory.

    Science.gov (United States)

    Nascimento, Daniel R; DePrince, A Eugene

    2017-07-06

    An explicitly time-dependent (TD) approach to equation-of-motion (EOM) coupled-cluster theory with single and double excitations (CCSD) is implemented for simulating near-edge X-ray absorption fine structure in molecular systems. The TD-EOM-CCSD absorption line shape function is given by the Fourier transform of the CCSD dipole autocorrelation function. We represent this transform by its Padé approximant, which provides converged spectra in much shorter simulation times than are required by the Fourier form. The result is a powerful framework for the blackbox simulation of broadband absorption spectra. K-edge X-ray absorption spectra for carbon, nitrogen, and oxygen in several small molecules are obtained from the real part of the absorption line shape function and are compared with experiment. The computed and experimentally obtained spectra are in good agreement; the mean unsigned error in the predicted peak positions is only 1.2 eV. We also explore the spectral signatures of protonation in these molecules.

  16. Solar polarimetry in the K I D2 line : A novel possibility for a stratospheric balloon

    Science.gov (United States)

    Quintero Noda, C.; Villanueva, G. L.; Katsukawa, Y.; Solanki, S. K.; Orozco Suárez, D.; Ruiz Cobo, B.; Shimizu, T.; Oba, T.; Kubo, M.; Anan, T.; Ichimoto, K.; Suematsu, Y.

    2018-03-01

    Of the two solar lines, K I D1 and D2, almost all attention so far has been devoted to the D1 line, as D2 is severely affected by an O2 atmospheric band. This, however, makes the latter appealing for balloon and space observations from above (most of) the Earth's atmosphere. We estimate the residual effect of the O2 band on the K I D2 line at altitudes typical for stratospheric balloons. Our aim is to study the feasibility of observing the 770 nm window. Specifically, this paper serves as a preparation for the third flight of the Sunrise balloon-borne observatory. The results indicate that the absorption by O2 is still present, albeit much weaker, at the expected balloon altitude. We applied the obtained O2 transmittance to K I D2 synthetic polarimetric spectra and found that in the absence of line-of-sight motions, the residual O2 has a negligible effect on the K I D2 line. On the other hand, for Doppler-shifted K I D2 data, the residual O2 might alter the shape of the Stokes profiles. However, the residual O2 absorption is sufficiently weak at stratospheric levels that it can be divided out if appropriate measurements are made, something that is impossible at ground level. Therefore, for the first time with Sunrise III, we will be able to perform polarimetric observations of the K I D2 line and, consequently, we will have improved access to the thermodynamics and magnetic properties of the upper photosphere from observations of the K I lines.

  17. Effective line intensity measurements of trans-nitrous acid (HONO) of the ν1 band near 3600 cm-1 using laser difference-frequency spectrometer

    Science.gov (United States)

    Maamary, Rabih; Fertein, Eric; Fourmentin, Marc; Dewaele, Dorothée; Cazier, Fabrice; Chen, Changshui; Chen, Weidong

    2017-07-01

    We report on the measurements of the effective line intensities of the ν1 fundamental band of trans-nitrous acid (trans-HONO) in the infrared near 3600 cm-1 (2.78 μm). A home-made widely tunable laser spectrometer based on difference-frequency generation (DFG) was used for this study. The strengths of 28 well-resolved absorption lines of the ν1 band were determined by scaling their absorption intensities to the well referenced absorption line intensity of the ν3 band of trans-HONO around 1250 cm-1 recorded simultaneously with the help of a DFB quantum cascade laser (QCL) spectrometer. The maximum measurement uncertainty of 12% in the line intensities is mainly determined by the uncertainty announced in the referenced line intensities, while the measurement precision in frequency positions of the absorption lines is better than 6×10-4 cm-1. The cross-measurement carried out in the present work allows one to perform intensity calibration using well referenced line parameters.

  18. Contribution to the study and to the development of continuous infrared absorption analyzers; Contribution a l'etude et a la mise au point des analyseurs en continu par absorption infrarouge

    Energy Technology Data Exchange (ETDEWEB)

    Coste, A [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-12-01

    The continuous infra-red absorption determination of corrosive gases implies the construction of an original single-beam spectrometer. The use of a vibration-rotation line means that the apparatus function has to undergo an alternating displacement: for one position this function is centered on the line, for other position it is placed close by, but away from any absorption. A non-linear relationship is derived between the concentration of the impurity under consideration, the optical density measured at the centre of the line and the total pressure of the gas mixture. The problem is then solved using an associated specific analog computer. The system is applicable to the determination of low concentrations. The principle proposed in then adapted to an analysis using a non-resolved vibration-rotation band. (authors) [French] Le dosage en continu par absorption infrarouge des gaz corrosifs, implique la construction d'un spectrometre original en simple faisceau. L'utilisation d'une raie de vibration - rotation, conduit a effectuer un deplacement alternatif de la fonction d'appareil: pour une position, celle-ci est centree sur la raie, pour l'autre position elle est placee a proximite mais en dehors de toute absorption. On etablit une relation non lineaire entre la concentration de l'impurete consideree, la densite optique mesuree au centre de la raie et la pression totale du melange gazeux. Le probleme est alors resolu par un calculateur analogique specifique associe. Le systeme s'applique au dosage des faibles concentrations. Le principe propose est ensuite adapte a l'analyse a partir d'une bande de vibration - rotation non resolue. (auteurs)

  19. Nasal Absorption of Macromolecules from Powder Formulations and Effects of Sodium Carboxymethyl Cellulose on Their Absorption.

    Directory of Open Access Journals (Sweden)

    Akiko Tanaka

    Full Text Available The nasal absorption of macromolecules from powder formulations and the effect of sodium carboxymethyl cellulose (CMC-Na as a pharmaceutical excipient on their absorption were studied. Model macromolecules were fluorescein isothiocyanate-labeled dextran (average molecular weight of 4.4kDa, FD4 and insulin. The plasma concentration of FD4 after application of the powder containing 50% starch (control was higher than that after application of the solution, and the absorption from 50% starch powder was enhanced by the substitution of starch with CMC-Na. The fractional absorption of FD4 after administration of the CMC-Na powder formulation was 30% and 40% higher than that after administration from the solution and the starch powder, respectively. The nasal absorption of insulin from the powder and the effect of CMC-Na were similar with those of FD4. The effective absorption of FD4 and insulin after application of powder with CMC-Na could be due to the increase in the nasal residence of FD4 and insulin. No damage in the nasal mucosa or dysfunction of the mucociliary clearance was observed after application of the drug powder and CMC-Na. The present findings indicate that nasal delivery of powder formulations with the addition of CMC-Na as an excipient is a promising approach for improving the nasal absorption of macromolecules.

  20. Conduction noise absorption by fiber-reinforced epoxy composites with carbon nanotubes

    International Nuclear Information System (INIS)

    Lee, Ok Hyoung; Kim, Sung-Soo; Lim, Yun-Soo

    2011-01-01

    Nearly all electronic equipment is susceptible to malfunction as a result of electromagnetic interference. In this study, glass fiber, and carbon fiber as a type reinforcement and epoxy as a matrix material were used to fabricate composite materials. In an attempt to increase the conduction noise absorption, carbon nanotubes were grown on the surface of glass fibers and carbon fibers. A microstrip line with characteristic impedance of 50 Ω in connection with network analyzer was used to measure the conduction noise absorption. In comparing a glass fiber/epoxy composite with a GF-CNT/Ep composite, it was demonstrated that the CNTs significantly influence the noise absorption property mainly due to increase in electric conductivity. In the carbon fiber composites, however, the effectiveness of CNTs on the degree of electric conductivity is negligible, resulting in a small change in reflection and transmission of an electromagnetic wave. - Research Highlights: → In this study, glass fiber and carbon fiber as a type reinforcement and epoxy as a matrix material were used to fabricate composite materials. In an attempt to increase the conduction noise absorption, carbon nanotubes (CNTs) were grown on the surface of glass fibers and carbon fibers. A microstrip line with characteristic impedance of 50 Ω in connection with network analyzer was used to measure the conduction noise absorption. → In comparing a glass fiber/epoxy composite with a GF-CNT/Ep composite, it was demonstrated that the CNTs significantly influence the noise absorption property mainly due to increase in electric conductivity. In the carbon fiber composites, however, the effectiveness of CNTs on the degree of electric conductivity is negligible, resulting in a small change in reflection and transmission of an electromagnetic wave.

  1. High-resolution continuum source electrothermal atomic absorption spectrometry: Linearization of the calibration curves within a broad concentration range

    Energy Technology Data Exchange (ETDEWEB)

    Katskov, Dmitri, E-mail: katskovda@tut.ac.za [Tshwane University of Technology, Chemistry Department, Pretoria 0001 (South Africa); Hlongwane, Miranda [Tshwane University of Technology, Chemistry Department, Pretoria 0001 (South Africa); Heitmann, Uwe [German Aerospace Center, Rose-Luxemburg Str. 2, 10178 Berlin (Germany); Florek, Stefan [ISAS-Leibniz-Institut fuer Analytische Wissenschaften e.V., Albert-Einstein-Str. 9,12489 Berlin (Germany)

    2012-05-15

    The calculation algorithm suggested provides linearization of the calibration curves in high-resolution continuum source electrothermal atomic absorption spectrometry. The algorithm is based on the modification of the function wavelength-integrated absorbance vs. concentration of analyte vapor in the absorption volume. According to the suggested approach, the absorption line is represented by a triangle for low and trapezium for high analyte vapor concentration in the absorption volume. The respective semi-empirical formulas include two linearization parameters, which depend on properties of the absorption line and characteristics of the atomizer and spectrometer. The parameters can be approximately evaluated from the theory and determined in practice from the original broad-range calibration curve. The parameters were found and the proposed calculation algorithm verified in the experiments on direct determination of Ag, Cd, Cu, Fe, Mn and Pb in the solutions within a concentration ranges from 0.15 to 625 {mu}g{center_dot}L{sup -1} using tube, platform tube and filter furnace atomizers. The use of various atomizers, lines, elements and atomization temperatures made possible the simulation of various practical analytical conditions. It was found that the algorithm and optimal linearization parameters made it possible to obtain for each line and atomizer linear approximations of the calibration curves within 3-4 orders of magnitude with correlation coefficients close to 0.999. The algorithm makes possible to employ a single line for the direct element determination over a broad concentration range. The sources of errors and the possibility of a priori theoretical evaluation of the linearization parameters are discussed. - Highlights: Black-Right-Pointing-Pointer New calculation algorithm for HR-CS ET AAS measurements was proposed and applied. Black-Right-Pointing-Pointer The suggested formulas include two parameters to be determined experimentally. Black

  2. Ultraviolet photometry from the orbiting astronomical observatory. XVI - The stellar Lyman-alpha absorption line

    Science.gov (United States)

    Savage, B. D.; Panek, R. J.

    1974-01-01

    The stellar Lyman-alpha line at 1216 A was observed in 29 lightly reddened stars of spectral type B2.5 to B9 by a far-UV spectrophotometer on OAO-2. The equivalent widths obtained range from 15 A at type B2.5 to 65 A at type B8; in the late-B stars, the L-alpha line removes 2 to 3% of the total stellar flux. In this sampling, the strength of the L-alpha line correlates well with measures of the Balmer discontinuity and Balmer line strengths; luminosity classification does not seem to affect the line strength. The observed line widths also agree with the predictions of Mihala's grid of non-LTE model atmospheres. In some cases, the L-alpha line influences the interstellar column densities reported in the interstellar OAO-2 L-alpha survey. Hence, these data toward lightly reddened B2 and B1.5 stars should be regarded as upper limits only.

  3. [Selected enhancement of different order stokes lines of SRS by using fluorescence of mixed dye solution].

    Science.gov (United States)

    Zuo, Hao-yi; Gao, Jie; Yang, Jing-guo

    2007-03-01

    A new method to enhance the intensity of the different orders of Stokes lines of SRS by using mixed dye fluorescence is reported. The Stokes lines from the second-order to the fifth-order of CCl4 were enhanced by the fluorescence of mixed R6G and RB solutions in different proportions of 20:2, 20:13 and 20:40 (R6g:Rb), respectively. It is considered that the Stokes lines from the second-order to the fifth-order are near the fluorescence peaks of the three mixed solutions, and far from the absorption peaks of R6g and Rb, so the enhancement effect dominates the absorption effect; as a result, these stokes lines are enhanced. On the contrary, the first-order stokes line is near the absorption peak of RB and far from the fluorescence peaks of the mixed solutions, which leads to the weakening of this stokes line. It is also reported that the first-order, the second-order and the third-order Stokes lines of benzene were enhanced by the fluorescence of mixed solutions of R6g and DCM with of different proportions. The potential application of this method is forecasted.

  4. Aerosol Absorption Measurements in MILAGRO.

    Science.gov (United States)

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

    2007-12-01

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

  5. Development of an x-ray beam line at the NSLS for studies in materials science using x-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Sayers, D.E.

    1989-01-01

    At the time of the submission of the original proposal more than 7 years ago, the X-11 PRT had set as a goal to develop one of the leading and most comprehensive x-ray absorption beam lines in the world. By any measure we have been successful. As is well documented in previous annual progress report and in the NSLS annual reports, our PRT has been extremely productive in a wide range of topics in materials science, solid state physics, chemistry and biology. Well over 100 papers have been published acknowledging the support of this contract and this continues at a rate of about 30 papers per year and about 20 invited presentations per year. Significant in this report are major studies in high T c compounds, advances in interface studies, new results in premelting phenomena, several pioneering studies in application of XAS to electrochemistry and significant progress in our understanding of the structure of amorphous chalcogenide systems and their photostructural changes

  6. Study of the dispersion phenomena connected with the absorption by recoilless nuclear resonance fluorescence; Etude des phenomenes de dispersion lies a l'absorption resonnante sans recul des noyaux atomiques

    Energy Technology Data Exchange (ETDEWEB)

    Imbert, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-12-01

    In nuclear resonance fluorescence as in the optical field abnormal dispersion curves are related to the absorption lines. It is possible, by using quadrupolar or magnetic splitting of the line in the case of recoilless resonance fluorescence (Moessbauer effect) to obtain differential dispersion effects between the two orthogonal linear or the two inverse circular components of the incident gamma radiation. These effects induce bi-refraction phenomena or Faraday rotation on the gamma beam, which have been studied on Fe-57 enriched absorbers. (author) [French] Comme dans le domaine optique, aux raies d'absorption de fluorescence resonnante des noyaux atomiques sont associees des courbes de dispersion anormale. Les decompositions des raies d'absorption de fluorescence resonnante sans recul (raies Moessbauer) par couplage quadrupolaire ou effet Zeeman permettent d'obtenir des effets dispersifs differentiels entre composantes lineaires orthogonales ou circulaires inverses du rayonnement gamma incident. Ces effets se traduisent par des phenomenes de birefringence ou de rotation Faraday, qui ont pu etre etudies sur des milieux enrichis en fer-57. (auteur)

  7. Enhanced Water Vapor Absorption within Tropospheric Clouds: A Partial Explanation for Anomalous Absorption

    Science.gov (United States)

    Crisp, David; Zuffada, Cinzia

    1996-01-01

    Comparisons between solar flux measurements and predictions obtained from theoretical radiative transfer models indicate that most of these models underestimate the globally averaged solar energy absorbed by cloudy atmospheres by up to 25Wm&sup-2;.The origin of this anomalous absorption has not yet been established, but it has been attributed to a variety of sources including oversimplified or missing physical processes in the existing models, uncertainties in the input data, and even measurement errors. We used a sophisticated atmospheric radiative transfer model to provide improved constraints on the physical processes that contribute to the absorption of solar radiation by Earth's atmosphere. The results are described herein.

  8. Fe-K LINE PROBING OF MATERIAL AROUND THE ACTIVE GALACTIC NUCLEUS CENTRAL ENGINE WITH SUZAKU

    International Nuclear Information System (INIS)

    Fukazawa, Yasushi; Hiragi, Kazuyoshi; Mizuno, Motohiro; Nishino, Sho; Hayashi, Katsuhiro; Yamasaki, Tomonori; Shirai, Hirohisa; Takahashi, Hiromitsu; Ohno, Masanori

    2011-01-01

    We systematically analyzed the high-quality Suzaku data of 88 Seyfert galaxies, about 31% of which are Compton-thick active galactic nuclei (AGNs). We obtained a clear relation between the absorption column density and the equivalent width (EW) of the 6.4 keV line above 10 23 cm -2 , suggesting a wide-ranging column density of 10 23 -10 24.5 cm -2 with a similar solid and an Fe abundance of 0.7-1.3 solar for Seyfert 2 galaxies. The EWs of the 6.4 keV line for Seyfert 1 galaxies are typically 40-120 eV, suggesting the existence of Compton-thick matter like the torus with a column density of >10 23 cm -2 and a solid angle of (0.15-0.4) x 4π, and no difference of neutral matter is visible between Seyfert 1 and 2 galaxies. An absorber with a lower column density of 10 21 -10 23 cm -2 for Compton-thin Seyfert 2 galaxies is suggested to be not a torus but an interstellar medium. These constraints can be understood by the fact that the 6.4 keV line intensity ratio against the 10-50 keV flux is almost identical within a range of 2-3 in many Seyfert galaxies. Interestingly, objects exist with a low EW, 10-30 eV, of the 6.4 keV line, suggesting that those torus subtends only a small solid angle of H >10 23 cm -2 indicates that the column density of the ionized material also increases together with that of the cold material. It is found that these features seem to change for brighter objects with more than several 10 44 erg s -1 such that the Fe-K line features become weak. This extends the previously known X-ray Baldwin effect on the neutral Fe-Kα line to ionized emission or absorption lines. The luminosity dependence of these properties, regardless of the scatter of black hole mass by two orders of magnitudes, indicates that the ionized material is associated with the structure of the parent galaxy rather than the outflow from the nucleus.

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

    Science.gov (United States)

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

    2012-04-01

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

  10. Application of Internal Standard Method for Several 3d-Transition Metallic Elements in Flame Atomic Absorption Spectrometry Using a Multi-wavelength High-resolution Spectrometer.

    Science.gov (United States)

    Toya, Yusuke; Itagaki, Toshiko; Wagatsuma, Kazuaki

    2017-01-01

    We investigated a simultaneous internal standard method in flame atomic absorption spectrometry (FAAS), in order to better the analytical precision of 3d-transition metals contained in steel materials. For this purpose, a new spectrometer system for FAAS, comprising a bright xenon lamp as the primary radiation source and a high-resolution Echelle monochromator, was employed to measure several absorption lines at a wavelength width of ca. 0.3 nm at the same time, which enables the absorbances of an analytical line and also an internal standard line to be estimated. In considering several criteria for selecting an internal standard element and the absorption line, it could be suggested that platinum-group elements: ruthenium, rhodium, or palladium, were suitable for an internal standard element to determine the 3d-transition metal elements, such as titanium, iron, and nickel, by measuring an appropriate pair of these absorption lines simultaneously. Several variances of the absorption signal, such as a variation in aspirated amounts of sample solution and a short-period drift of the primary light source, would be corrected and thus reduced, when the absorbance ratio of the analytical line to the internal standard line was measured. In Ti-Pd, Ni-Rh, and Fe-Ru systems chosen as typical test samples, the repeatability of the signal respnses was investigated with/without the internal standard method, resulting in better precision when the internal standard method was applied in the FAAS with a nitrous oxide-acetylene flame rather than an air-acetylene flame.

  11. EPR and optical absorption studies of VO2+ doped L-alanine (C3H7NO2) single crystals

    International Nuclear Information System (INIS)

    Biyik, Recep

    2009-01-01

    VO 2+ doped L-alanine (C 3 H 7 NO 2 ) single crystals and powders are examined by electron paramagnetic resonance (EPR) and optical absorption spectroscopy. Three magnetically different sites are resolved from angular variations of L-alanine single crystal EPR spectra. In some specific orientations each VO 2+ line splits into three superhyperfine lines with intensities of 1:2:1 and maximum splitting value of 2.23 mT. The local symmetries of VO 2+ complex sites are nearly axial. The optical absorption spectra show three bands. Spin Hamiltonian parameters are measured and molecular orbital coefficients are calculated by correlating EPR and optical absorption data for the central vanadyl ion.

  12. A novel multiplex absorption spectrometer for time-resolved studies

    Science.gov (United States)

    Lewis, Thomas; Heard, Dwayne E.; Blitz, Mark A.

    2018-02-01

    A Time-Resolved Ultraviolet/Visible (UV/Vis) Absorption Spectrometer (TRUVAS) has been developed that can simultaneously monitor absorption at all wavelengths between 200 and 800 nm with millisecond time resolution. A pulsed photolysis laser (KrF 248 nm) is used to initiate chemical reactions that create the target species. The absorption signals from these species evolve as the composition of the gas in the photolysis region changes over time. The instrument can operate at pressures over the range ˜10-800 Torr and can measure time-resolved absorbances systems (in particular the Herriott cell), there are fundamental differences, most notably the ability to adjust each mirror to maximise the overlap between the probe beam and the photolysis laser. Another feature which aids the sensitivity and versatility of the system is the use of 2 high-throughput spectrographs coupled with sensitive line-array CCDs, which can measure absorbance from ˜200 to 800 nm simultaneously. The capability of the instrument is demonstrated via measurements of the absorption spectrum of the peroxy radical, HOCH2CH2O2, and its self-reaction kinetics.

  13. Airborne Measurements of CO2 Column Absorption and Range Using a Pulsed Direct-Detection Integrated Path Differential Absorption Lidar

    Science.gov (United States)

    Abshire, James B.; Riris, Haris; Weaver, Clark J.; Mao, Jianping; Allan, Graham R.; Hasselbrack, William E.; Browell, Edward V.

    2013-01-01

    We report on airborne CO2 column absorption measurements made in 2009 with a pulsed direct-detection lidar operating at 1572.33 nm and utilizing the integrated path differential absorption technique. We demonstrated these at different altitudes from an aircraft in July and August in flights over four locations in the central and eastern United States. The results show clear CO2 line shape and absorption signals, which follow the expected changes with aircraft altitude from 3 to 13 km. The lidar measurement statistics were also calculated for each flight as a function of altitude. The optical depth varied nearly linearly with altitude, consistent with calculations based on atmospheric models. The scatter in the optical depth measurements varied with aircraft altitude as expected, and the median measurement precisions for the column varied from 0.9 to 1.2 ppm. The altitude range with the lowest scatter was 810 km, and the majority of measurements for the column within it had precisions between 0.2 and 0.9 ppm.

  14. 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

  15. IUE observations of interstellar Si IV and C IV lines observed in the spectra of Wolf-Rayet stars

    International Nuclear Information System (INIS)

    Smith, L.J.; Willis, A.J.; Wilson, R.

    1980-01-01

    Recent IUE observations of Wolf-Rayet stars show narrow absorption lines in the highly ionized species of Si IV and C IV. The strengths of these 'interstellar' Si IV and C IV lines observed in the spectra of 10 WR stars and two other early-type stars are compared. Of the WR sample, six stars exhibit very strong Si IV and C IV lines (Wsub(lambda) approximately 0.3 to 0.5 A) whilst the other four stars show much weaker lines (Wsub(lambda) approximately 0.1 A). There is no correlation between the strengths of these lines with either stellar distance or colour excess. The weaker absorptions may arise in the individual stellar H II regions, the observed strengths being consistent with those expected for stars with Tsub(eff) = 30 000 K. Five of the other stars which exhibit very strong absorptions lie in the line of sight to active interstellar regions (Cygnus and Carina nebulae) and it is considered probable that, in addition to their H II region components, the bulk of the strong Si IV and C IV absorptions originate in hot gas associated with these active regions. In the case of the WN5 star HD 50896 violet-displaced components are observed in the interstellar lines of low ionization species. These are thought to be produced in the ring nebula S308 surrounding HD 50896. (author)

  16. Fourier Transform and Photoacoustic Absorption Spectra of Ethylene within 6035 6210 cm-1: Comparative Measurements

    International Nuclear Information System (INIS)

    Kapitanov, V.A.; Solodov, A.M.; Petrova, T.M.; Ponomarev, Y.N.

    2010-01-01

    Measurements of ethylene absorption spectra with Fourier Transform (FT) and Photoacoustic (PA) spectrometers within 6035-6210 cm -1 are described. The methodology used for building the frequency scale for both spectrometers is presented. The methane absorption spectrum, included into the HITRAN database, was used in both cases to calibrate the frequency scale. Ethylene absorption spectra were obtained with the two recording methods; a coincidence of the measured line center positions was obtained with an accuracy of 0.0005 cm -1

  17. Radiation damage of light guide fibers in gamma radiation field - on-line monitoring of absorption centers formation

    International Nuclear Information System (INIS)

    Blaha, J.; Simane, C.; Finger, M.; Slunecka, M.; Finger, M. Jr.; Sluneckova, V.; Janata, A.; Vognar, M.; Sulc, M.

    2004-01-01

    The kinetics of radiation-induced changes of absorption coefficient was studied by online transmission spectra measurement for two different Kuraray light guide fibers. The samples were irradiated by bremsstrahlung gamma radiation, dose rates were from 2 Gy/s to 25 Gy/s. The kinetic coefficients both for absorption centers formation and for recovery processes were calculated. Good agreement of experimental data and simple one-short-lived absorption center model were received for radiation-hard light guide Kuraray (KFC). The more complicated process was observed on Kuraray (PSM) clear fiber. It was caused by the reaction of the oxygen dissolved in fiber and created radicals. The results are very useful for prediction of an optical fibers response in conditions of new nuclear and particle physics experiments. (author)

  18. HIGH-VELOCITY LINE FORMING REGIONS IN THE TYPE Ia SUPERNOVA 2009ig

    International Nuclear Information System (INIS)

    Marion, G. H.; Foley, Ryan J.; Challis, Peter; Kirshner, Robert P.; Vinko, Jozsef; Wheeler, J. Craig; Silverman, Jeffrey M.; Hsiao, Eric Y.; Brown, Peter J.; Filippenko, Alexei V.; Garnavich, Peter; Landsman, Wayne B.; Parrent, Jerod T.; Pritchard, Tyler A.; Roming, Peter W. A.; Wang, Xiaofeng

    2013-01-01

    We report measurements and analysis of high-velocity (HVF) (>20,000 km s –1 ) and photospheric absorption features in a series of spectra of the Type Ia supernova (SN) 2009ig obtained between –14 days and +13 days with respect to the time of maximum B-band luminosity (B-max). We identify lines of Si II, Si III, S II, Ca II, and Fe II that produce both HVF and photospheric-velocity (PVF) absorption features. SN 2009ig is unusual for the large number of lines with detectable HVF in the spectra, but the light-curve parameters correspond to a slightly overluminous but unexceptional SN Ia (M B = –19.46 mag and Δm 15 (B) = 0.90 mag). Similarly, the Si II λ6355 velocity at the time of B-max is greater than 'normal' for an SN Ia, but it is not extreme (v Si = 13,400 km s –1 ). The –14 days and –13 days spectra clearly resolve HVF from Si II λ6355 as separate absorptions from a detached line forming region. At these very early phases, detached HVF are prevalent in all lines. From –12 days to –6 days, HVF and PVF are detected simultaneously, and the two line forming regions maintain a constant separation of about 8000 km s –1 . After –6 days all absorption features are PVF. The observations of SN 2009ig provide a complete picture of the transition from HVF to PVF. Most SNe Ia show evidence for HVF from multiple lines in spectra obtained before –10 days, and we compare the spectra of SN 2009ig to observations of other SNe. We show that each of the unusual line profiles for Si II λ6355 found in early-time spectra of SNe Ia correlate to a specific phase in a common development sequence from HVF to PVF

  19. Automatic Locking of Laser Frequency to an Absorption Peak

    Science.gov (United States)

    Koch, Grady J.

    2006-01-01

    An electronic system adjusts the frequency of a tunable laser, eventually locking the frequency to a peak in the optical absorption spectrum of a gas (or of a Fabry-Perot cavity that has an absorption peak like that of a gas). This system was developed to enable precise locking of the frequency of a laser used in differential absorption LIDAR measurements of trace atmospheric gases. This system also has great commercial potential as a prototype of means for precise control of frequencies of lasers in future dense wavelength-division-multiplexing optical communications systems. The operation of this system is completely automatic: Unlike in the operation of some prior laser-frequency-locking systems, there is ordinarily no need for a human operator to adjust the frequency manually to an initial value close enough to the peak to enable automatic locking to take over. Instead, this system also automatically performs the initial adjustment. The system (see Figure 1) is based on a concept of (1) initially modulating the laser frequency to sweep it through a spectral range that includes the desired absorption peak, (2) determining the derivative of the absorption peak with respect to the laser frequency for use as an error signal, (3) identifying the desired frequency [at the very top (which is also the middle) of the peak] as the frequency where the derivative goes to zero, and (4) thereafter keeping the frequency within a locking range and adjusting the frequency as needed to keep the derivative (the error signal) as close as possible to zero. More specifically, the system utilizes the fact that in addition to a zero crossing at the top of the absorption peak, the error signal also closely approximates a straight line in the vicinity of the zero crossing (see Figure 2). This vicinity is the locking range because the linearity of the error signal in this range makes it useful as a source of feedback for a proportional + integral + derivative control scheme that

  20. On the synthesis of resonance lines in dynamical models of structured hot-star winds

    Science.gov (United States)

    Puls, J.; Owocki, S. P.; Fullerton, A. W.

    1993-01-01

    We examine basic issues involved in synthesizing resonance-line profiles from 1-D, dynamical models of highly structured hot-star winds. Although these models exhibit extensive variations in density as well as velocity, the density scale length is still typically much greater than the Sobolev length. The line transfer is thus treated using a Sobolev approach, as generalized by Rybicki & Hummer (1978) to take proper account of the multiple Sobolev resonances arising from the nonmonotonic velocity field. The resulting reduced-lambda-matrix equation describing nonlocal coupling of the source function is solved by iteration, and line profiles are then derived from formal solution integration using this source function. Two more approximate methods that instead use either a stationary or a structured, local source function yield qualitatively similar line-profiles, but are found to violate photon conservation by 10% or more. The full results suggest that such models may indeed be able to reproduce naturally some of the qualitative properties long noted in observed UV line profiles, such as discrete absorption components in unsaturated lines, or the blue-edge variability in saturated lines. However, these particular models do not yet produce the black absorption troughs commonly observed in saturated lines, and it seems that this and other important discrepancies (e.g., in acceleration time scale of absorption components) may require development of more complete models that include rotation and other 2-D and/or 3-D effects.

  1. Mercury absorption in aqueous hypochlorite

    International Nuclear Information System (INIS)

    Zhao, L.L.; Rochelle, G.T.

    1999-01-01

    The absorption of elemental Hg vapor into aqueous hypochlorite was measured in a stirred tank reactor at 25 and 55C. NaOCl strongly absorbs Hg even at high pH. Low pH, high Cl - and high-temperature favor mercury absorption. Aqueous free Cl 2 was the active species that reacted with mercury. However, chlorine desorption was evident at high Cl - and pH 15 M -1 s -1 at 25C and 1.4x10 17 M -1 s -1 at 55C. Gas-phase reaction was observed between Hg and Cl 2 on apparatus surfaces. Strong mercury absorption in water was also detected with Cl 2 present. Results indicate that the chlorine concentration, moisture, and surface area contribute positively to mercury removal. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  2. On the limitations of statistical absorption studies with the Sloan Digital Sky Surveys I-III

    Science.gov (United States)

    Lan, Ting-Wen; Ménard, Brice; Baron, Dalya; Johnson, Sean; Poznanski, Dovi; Prochaska, J. Xavier; O'Meara, John M.

    2018-04-01

    We investigate the limitations of statistical absorption measurements with the SDSS optical spectroscopic surveys. We show that changes in the data reduction strategy throughout different data releases have led to a better accuracy at long wavelengths, in particular for sky line subtraction, but a degradation at short wavelengths with the emergence of systematic spectral features with an amplitude of about one percent. We show that these features originate from inaccuracy in the fitting of modeled F-star spectra used for flux calibration. The best-fit models for those stars are found to systematically over-estimate the strength of metal lines and under-estimate that of Lithium. We also identify the existence of artifacts due to masking and interpolation procedures at the wavelengths of the hydrogen Balmer series leading to the existence of artificial Balmer α absorption in all SDSS optical spectra. All these effects occur in the rest-frame of the standard stars and therefore present Galactic longitude variations due to the rotation of the Galaxy. We demonstrate that the detection of certain weak absorption lines reported in the literature are solely due to calibration effects. Finally, we discuss new strategies to mitigate these issues.

  3. Chlorophyll specific absorption coefficient and phytoplankton biomass in the Red Sea

    KAUST Repository

    Tiwari, Surya Prakash

    2015-01-01

    The role of total particulate matter, the sum of phytoplankton and nonalgal particles, is essential to understanding the distribution and pathways of particulate carbon in the ocean. Their relative contributions to light absorption and scattering are fundamental to understanding remotely sensed ocean color. Until recently, data regarding the contribution of phytoplankton and algal particles to the inherent optical properties of the Red Sea was nonexistent. Some of the first measurements of these inherent optical properties in the Red Sea including phytoplankton specific absorption coefficients (aph*(λ)) were obtained by the TARA Oceans expedition in January 2010. From these observations, chlorophyll a was calculated using the Line Height Method (LHM) that minimizes the contribution to total and particulate absorption by non-algal particles (NAP) and CDOM. Bricaud and Stramski’s (1990) a method was then used to decompose hyperspectral total particulate absorption into the contributions by phytoplankton and nonalgal particles.

  4. A Comprehensive X-Ray Absorption Model for Atomic Oxygen

    Science.gov (United States)

    Gorczyca, T. W.; Bautista, M. A.; Hasoglu, M. F.; Garcia, J.; Gatuzz, E.; Kaastra, J. S.; Kallman, T. R.; Manson, S. T.; Mendoza, C.; Raassen, A. J. J.; hide

    2013-01-01

    An analytical formula is developed to accurately represent the photoabsorption cross section of atomic Oxygen for all energies of interest in X-ray spectral modeling. In the vicinity of the K edge, a Rydberg series expression is used to fit R-matrix results, including important orbital relaxation effects, that accurately predict the absorption oscillator strengths below threshold and merge consistently and continuously to the above-threshold cross section. Further, minor adjustments are made to the threshold energies in order to reliably align the atomic Rydberg resonances after consideration of both experimental and observed line positions. At energies far below or above the K-edge region, the formulation is based on both outer- and inner-shell direct photoionization, including significant shake-up and shake-off processes that result in photoionization-excitation and double-photoionization contributions to the total cross section. The ultimate purpose for developing a definitive model for oxygen absorption is to resolve standing discrepancies between the astronomically observed and laboratory-measured line positions, and between the inferred atomic and molecular oxygen abundances in the interstellar medium from XSTAR and SPEX spectral models.

  5. Infrared absorption by molecular gases as a probe of nanoporous silica xerogel and molecule-surface collisions: Low-pressure results

    Science.gov (United States)

    Vander Auwera, J.; Ngo, N. H.; El Hamzaoui, H.; Capoen, B.; Bouazaoui, M.; Ausset, P.; Boulet, C.; Hartmann, J.-M.

    2013-10-01

    Transmission spectra of gases confined (but not adsorbed) within the pores of a 1.4-cm-thick silica xerogel sample have been recorded between 2.5 and 5 μm using a high-resolution Fourier transform spectrometer. This was done for pure CO, CO2, N2O, H2O, and CH4 at room temperature and pressures of a few hectopascals. Least-squares fits of measured absorption lines provide the optical-path lengths within the confined (LC) and free (LF) gas inside the absorption cell and the half width at half maximum ΓC of the lines of the confined gases. The values of LC and LF retrieved using numerous transitions of all studied species are very consistent. Furthermore, LC is in satisfactory agreement with values obtained from independent measurements, thus showing that reliable information on the open porosity volume can be retrieved from an optical experiment. The values of ΓC, here resulting from collisions of the molecules with the inner surfaces of the xerogel pores, are practically independent of the line for each gas and inversely proportional to the square root of the probed-molecule molar mass. This is a strong indication that, for the studied transitions, a single collision of a molecule with a pore surface is sufficient to change its rotational state. A previously proposed simple model, used for the prediction of the line shape, leads to satisfactory agreement with the observations. It also enables a determination of the average pore size, bringing information complementary to that obtained from nitrogen adsorption porosimetry.

  6. Microwave absorption in the singlet paramagnet HoVO4 in high pulsed magnetic fields up to 40 T

    International Nuclear Information System (INIS)

    Goiran, M.; Klingeler, R.; Kazei, Z.A.; Snegirev, V.V.

    2007-01-01

    Microwave absorption of the rare-earth (RE) oxide compound HoVO 4 (tetragonal-zircon structure) is investigated in pulsed magnetic fields up to 40 T in the low-temperature range. For a magnetic field along the tetragonal crystal axis a few resonance absorption lines are observed at the wavelengths 871, 406 and 305 μm corresponding to electron transitions from the ground and low-lying energy levels of the Ho 3+ ion. In addition, broad non-resonance absorption is observed at 871 and 406 μm in fields up to 15 T. The positions and intensities of the observed resonance lines are described quite well within the crystal field formalism with the known crystal field parameters. The effects of the small orthorhombic component of the crystal field, magnetic field misorientation out the symmetry axis and various pair interactions on the absorption spectra in HoVO 4 are analyzed and discussed

  7. Calcium absorption from fortified ice cream formulations compared with calcium absorption from milk.

    Science.gov (United States)

    van der Hee, Regine M; Miret, Silvia; Slettenaar, Marieke; Duchateau, Guus S M J E; Rietveld, Anton G; Wilkinson, Joy E; Quail, Patricia J; Berry, Mark J; Dainty, Jack R; Teucher, Birgit; Fairweather-Tait, Susan J

    2009-05-01

    Optimal bone mass in early adulthood is achieved through appropriate diet and lifestyle, thereby protecting against osteoporosis and risk of bone fracture in later life. Calcium and vitamin D are essential to build adequate bones, but calcium intakes of many population groups do not meet dietary reference values. In addition, changes in dietary patterns are exacerbating the problem, thereby emphasizing the important role of calcium-rich food products. We have designed a calcium-fortified ice cream formulation that is lower in fat than regular ice cream and could provide a useful source of additional dietary calcium. Calcium absorption from two different ice cream formulations was determined in young adults and compared with milk. Sixteen healthy volunteers (25 to 45 years of age), recruited from the general public of The Netherlands, participated in a randomized, reference-controlled, double-blind cross-over study in which two test products and milk were consumed with a light standard breakfast on three separate occasions: a standard portion of ice cream (60 g) fortified with milk minerals and containing a low level (3%) of butter fat, ice cream (60 g) fortified with milk minerals and containing a typical level (9%) of coconut oil, and reduced-fat milk (1.7% milk fat) (200 mL). Calcium absorption was measured by the dual-label stable isotope technique. Effects on calcium absorption were evaluated by analysis of variance. Fractional absorption of calcium from the 3% butterfat ice cream, 9% coconut oil ice cream, and milk was 26%+/-8%, 28%+/-5%, and 31%+/-9%, respectively, and did not differ significantly (P=0.159). Results indicate that calcium bioavailability in the two calcium-fortified ice cream formulations used in this study is as high as milk, indicating that ice cream may be a good vehicle for delivery of calcium.

  8. Effect of exciton polaritons of absorption edge of GaTe

    International Nuclear Information System (INIS)

    Kurbatov, L.N.; Dirochka, A.I.; Sosin, V.A.

    1979-01-01

    The experimental results, pointing to the dependence of spectral and integral coefficients of exciton absorption as well as to the exciton relaxation parameter γsub(0) over the exciton zone on the sample thickness, are presented. It is tried to explain the inverse dependences of absorption intensity in the maximum of αsub(max) and γsub(0) exciton line within the limits of polariton theory. The values of polariton free path length in GaTe at various temperatures, as well as the volume γsub(vol.) and surface γsub(surf.) parameters of exciton relaxation over the exciton zone are discussed

  9. Mg II Line Variation of 32 Cygni

    Directory of Open Access Journals (Sweden)

    Young Woon Kang

    1992-12-01

    Full Text Available The Mg II lines have been extracted from the IUE archival spectra of 32 Cygni to investigate the effect of the atmospheric eclipse. The UV light curve has been reduced from the continuum flux at the center wavelength of 2807.5 Å in the IUE spectra. The equivalent width of the Mg II k absoption line has been measured for each spectra. The results of the light variation and flux tracing of the absorption line at the vicinity of the primary eclipse confirmed the atmospheric eclipse. The atmospheric effect lasted until the phase 0.06 in the absorptin line tracing, while it lasted until the phase 0.02 in the UV light curve, respectively.

  10. Modulation of intestinal absorption of calcium

    Energy Technology Data Exchange (ETDEWEB)

    Fournier, P; Dupuis, Y [Ecole Pratique des Hautes Etudes, 75 - Paris (France); Paris-11 Univ., 92 - Chatenay-Malabry (France))

    1975-01-01

    Absorption of ingested calcium (2ml of a 10mM CaCl/sub 2/ solution + /sup 45/Ca) by the adult rat was shown to be facilitated by the simultaneous ingestion of an active carbohydrate, L-arabinose. As the carbohydrate concentration is increased from 10 to 200mM, the absorption of calcium is maximised at a level corresponding to about twice the control absorption level. A similar doubling of calcium absorption is obtained when a 100mM concentration of any one of a number of other carbohydrates is ingested simultaneously with a 10mM CaCl/sub 2/ solution. Conversely, the simultaneous ingestion of increasing doses (10 to 100mM) of phosphate (NaH/sub 2/PO/sub 4/) with a 10mM CaCl/sub 2/ solution results in decreased /sup 45/Ca absorption and retention by the adult rat. The maximum inhibition of calcium absorption by phosphate is independent of the concentration of the ingested calcium solution (from 5 to 50mM CaCl/sub 2/). The simultaneous ingestion of CaCl/sub 2/ (10mM) with lactose and sodium phosphate (50 and 10mM respectively) shows that the activation effect of lactose upon /sup 45/Ca absorption may be partly dissimulated by the presence of phosphate. These various observations indicate that, within a large concentration range (2 to 50mM CaCl/sub 2/) calcium absorption appears to be a precisely modulated diffusion process. Calcium absorption varies (between minimum and maximum levels) as a function of the state of saturation by the activators (carbohydrates) and inhibitors (phosphate) of the calcium transport system.

  11. Determination of phosphorus, sulfur and the halogens using high-temperature molecular absorption spectrometry in flames and furnaces-A review

    International Nuclear Information System (INIS)

    Welz, Bernhard; Lepri, Fabio G.; Araujo, Rennan G.O.; Ferreira, Sergio L.C.; Huang Maodong; Okruss, Michael; Becker-Ross, Helmut

    2009-01-01

    The literature about the investigation of molecular spectra of phosphorus, sulfur and the halogens in flames and furnaces, and the use of these spectra for the determination of these non-metals has been reviewed. Most of the investigations were carried out using conventional atomic absorption spectrometers, and there were in essence two different approaches. In the first one, dual-channel spectrometers with a hydrogen or deuterium lamp were used, applying the two-line method for background correction; in the second one, a line source was used that emitted an atomic line, which overlapped with the molecular spectrum. The first approach had the advantage that any spectral interval could be accessed, but it was susceptible to spectral interference; the second one had the advantage that the conventional background correction systems could be used to minimize spectral interferences, but had the problem that an atomic line had to be found, which was overlapping sufficiently well with the maximum of the molecular absorption spectrum. More recently a variety of molecular absorption spectra were investigated using a low-resolution polychromator with a CCD array detector, but no attempt was made to use this approach for quantitative determination of non-metals. The recent introduction and commercial availability of high-resolution continuum source atomic absorption spectrometers is offering completely new possibilities for molecular absorption spectrometry and its use for the determination of non-metals. The use of a high-intensity continuum source together with a high-resolution spectrometer and a CCD array detector makes possible selecting the optimum wavelength for the determination and to exclude most spectral interferences.

  12. Pulsed Lidar Measurements of Atmospheric CO2 Column Absorption and Range During the ASCENDS 2009-2011 Airborne Campaigns

    Science.gov (United States)

    Abshire, J. B.; Weaver, C. J.; Riris, H.; Mao, J.; Sun, X.; Allan, G. R.; Hasselbrack, W. E.; Browell, E. V.

    2012-01-01

    We have developed a pulsed lidar technique for measuring the tropospheric CO2 concentrations as a candidate for NASA's ASCENDS mission and have demonstrated the CO2 and O2 measurements from aircraft. Our technique uses two pulsed lasers allowing simultaneous measurement of a single CO2 absorption line near 1572 nm, O2 extinction in the Oxygen A-band, surface height and backscatter profile. The lasers are stepped in wavelength across the CO2 line and an O2 line doublet during the measurement. The column densities for the CO2 and O2 are estimated from the differential optical depths (DOD) of the scanned absorption lines via the IPDA technique. For the 2009 ASCENDS campaign we flew the CO2 lidar only on a Lear-25 aircraft, and measured the absorption line shapes of the CO2 line using 20 wavelength samples per scan. Measurements were made at stepped altitudes from 3 to 12.6 km over the Lamont OK, central Illinois, North Carolina, and over the Virginia Eastern Shore. Although the received signal energies were weaker than expected for ASCENDS, clear C02 line shapes were observed at all altitudes. Most flights had 5-6 altitude steps with 200-300 seconds of recorded measurements per step. We averaged every 10 seconds of measurements and used a cross-correlation approach to estimate the range to the scattering surface and the echo pulse energy at each wavelength. We then solved for the best-fit CO2 absorption line shape, and calculated the DOD of the fitted CO2 line, and computed its statistics at the various altitude steps. We compared them to CO2 optical depths calculated from spectroscopy based on HITRAN 2008 and the column number densities calculated from the airborne in-situ readings. The 2009 measurements have been analyzed in detail and they were similar on all flights. The results show clear CO2 line shape and absorption signals, which follow the expected changes with aircraft altitude from 3 to 13 km. They showed the expected nearly the linear dependence of DOD vs

  13. Application of escape probability to line transfer in laser-produced plasmas

    International Nuclear Information System (INIS)

    Lee, Y.T.; London, R.A.; Zimmerman, G.B.; Haglestein, P.L.

    1989-01-01

    In this paper the authors apply the escape probability method to treat transfer of optically thick lines in laser-produced plasmas in plan-parallel geometry. They investigate the effect of self-absorption on the ionization balance and ion level populations. In addition, they calculate such effect on the laser gains in an exploding foil target heated by an optical laser. Due to the large ion streaming motion in laser-produced plasmas, absorption of an emitted photon occurs only over the length in which the Doppler shift is equal to the line width. They find that the escape probability calculated with the Doppler shift is larger compared to the escape probability for a static plasma. Therefore, the ion streaming motion contributes significantly to the line transfer process in laser-produced plasmas. As examples, they have applied escape probability to calculate transfer of optically thick lines in both ablating slab and exploding foil targets under irradiation of a high-power optical laser

  14. Nustar Reveals an Intrinsically X-ray Weak Broad Absorption Line Quasar in the Ultraluminous Infrared Galaxy Markarian 231

    Science.gov (United States)

    Teng, Stacy H.; Brandt. W. N.; Harrison, F. A.; Luo, B.; Alexander, D. M.; Bauer, F. E.; Boggs, S. E.; Christensen, F. E.; Comastri, A.; Craig, W. W.; hide

    2014-01-01

    We present high-energy (3-30 keV) NuSTAR observations of the nearest quasar, the ultraluminous infrared galaxy (ULIRG) Markarian 231 (Mrk 231), supplemented with new and simultaneous low-energy (0.5-8 keV) data from Chandra. The source was detected, though at much fainter levels than previously reported, likely due to contamination in the large apertures of previous non-focusing hard X-ray telescopes. The full band (0.5-30 keV) X-ray spectrum suggests the active galactic nucleus (AGN) in Mrk 231 is absorbed by a patchy and Compton-thin N(sub H) approx. 1.2(sup +0.3) sub-0.3) x 10(exp 23) / sq cm) column. The intrinsic X-ray luminosity L(sub 0.5-30 Kev) approx. 1.0 x 10(exp 43) erg /s) is extremely weak relative to the bolometric luminosity where the 2-10 keV to bolometric luminosity ratio is approx. 0.03% compared to the typical values of 2-15%. Additionally, Mrk 231 has a low X-ray-to-optical power law slope alpha(sub 0X) approx. -1.7. It is a local example of a low-ionization broad absorption line (LoBAL) quasar that is intrinsically X-ray weak. The weak ionizing continuum may explain the lack of mid-infrared [O IV], [Ne V], and [Ne VI] fine-structure emission lines which are present in sources with otherwise similar AGN properties. We argue that the intrinsic X-ray weakness may be a result of the super-Eddington accretion occurring in the nucleus of this ULIRG, and may also be naturally related to the powerful wind event seen in Mrk 231, a merger remnant escaping from its dusty cocoon.

  15. Reverse-Engineering Laboratory Astrophysics: Oxygen Inner-shell Absorption in the ISM

    Science.gov (United States)

    Garcia, J.; Gatuzz, E.; Kallman, T. R.; Mendoza, C.; Gorczyca, T. W.

    2017-01-01

    The modeling of X-ray spectra from photoionized astrophysical plasmas has been significantly improved due to recent advancements in the theoretical and numerical frameworks, as well as a consolidated and reliable atomic database of inner-shell transitions for all the relevant ions. We discuss these developments and the current state of X-ray spectral modeling in the context of oxygen cold absorption in the interstellar medium (ISM). Unconventionally, we use high-resolution astrophysical observations to accurately determine line positions, and adjust the theoretical models for a comprehensive interpretation of the observed X-ray spectra. This approach has brought to light standing discrepancies in the neutral oxygen absorption-line positions determined from observations and laboratory measurements. We give an overview of our current efforts to devise a definitive model of oxygen photoabsorption that can help to resolve the existing controversy regarding ISM atomic and molecular fractions.

  16. Measurement of the parameters of non-stationary gas flows by diode laser absorption spectroscopy in case of high temperature and high pressure

    International Nuclear Information System (INIS)

    Bolshov, M.A.; Liger, V.V.; Kuritsyn, Yu.A.; Mironenko, V.R.; Ponurovskii, Ya.Ya.; Kolesnikov, O.M.

    2017-01-01

    Experimental version of diode laser absorption spectrometer (DLAS) for contactless measurements of temperature and water vapor concentration in supersonic gas flows is developed. The spectrometer can be used for the measurements of temperature up to 2500 K and total pressure up to 3 atm. The technique is based on the registration of the transient absorption spectra of a target molecules and fitting of the experimental spectra by the simulated ones constructed using the spectroscopic databases. The temperature is inferred from the ratio of the intensities of the absorption lines with different low energy levels. In gas media with the above parameters the absorption lines are broadened which demands the use of two diode lasers (DL) working in different spectral ranges. The software for selection of the optimal line combinations was developed. The combination of two strong lines in the spectral ranges 1.39 μ and 1.34 μ was selected as the optimal one. The efficiency of the developed technique was exemplified in the first set of the experiments in conditions of real propulsion in Zhukovsky Central Aerohydrodynamic Institute (TsAGI) for the temperatures within 500-2200 K range and total pressure up to 3 atm.

  17. [Study on lead absorption in pumpkin by atomic absorption spectrophotometry].

    Science.gov (United States)

    Li, Zhen-Xia; Sun, Yong-Dong; Chen, Bi-Hua; Li, Xin-Zheng

    2008-07-01

    A study was carried out on the characteristic of lead absorption in pumpkin via atomic absorption spectrophotometer. The results showed that lead absorption amount in pumpkin increased with time, but the absorption rate decreased with time; And the lead absorption amount reached the peak in pH 7. Lead and cadmium have similar characteristic of absorption in pumpkin.

  18. Effect of self-absorption correction on surface hardness estimation of Fe-Cr-Ni alloys via LIBS.

    Science.gov (United States)

    Ramezanian, Zahra; Darbani, Seyyed Mohammad Reza; Majd, Abdollah Eslami

    2017-08-20

    The effect of self-absorption was investigated on the estimation of surface hardness of Fe-Cr-Ni metallic alloys by the laser-induced breakdown spectroscopy (LIBS) technique. For this purpose, the linear relationship between the ratio of chromium ionic to atomic line intensities (CrII/CrI) and surface hardness was studied, both before and after correcting the self-absorption effect. The correlation coefficient significantly increased from 47% to 90% after self-absorption correction. The results showed the measurements of surface hardness using LIBS can be more accurate and valid by correcting the self-absorption effect.

  19. Relative absorption and dermal loading of chemical substances: Consequences for risk assessment

    NARCIS (Netherlands)

    Buist, H.E.; Schaafsma, G.; Sandt, J.J.M. van de

    2009-01-01

    Quantification of skin absorption is an essential step in reducing the uncertainty of dermal risk assessment. Data from literature indicate that the relative dermal absorption of substances is dependent on dermal loading. Therefore, an internal exposure calculated with absorption data determined at

  20. Supersonic Mass Flux Measurements via Tunable Diode Laser Absorption and Non-Uniform Flow Modeling

    Science.gov (United States)

    Chang, Leyen S.; Strand, Christopher L.; Jeffries, Jay B.; Hanson, Ronald K.; Diskin, Glenn S.; Gaffney, Richard L.; Capriotti, Diego P.

    2011-01-01

    Measurements of mass flux are obtained in a vitiated supersonic ground test facility using a sensor based on line-of-sight (LOS) diode laser absorption of water vapor. Mass flux is determined from the product of measured velocity and density. The relative Doppler shift of an absorption transition for beams directed upstream and downstream in the flow is used to measure velocity. Temperature is determined from the ratio of absorption signals of two transitions (lambda(sub 1)=1349 nm and lambda(sub 2)=1341.5 nm) and is coupled with a facility pressure measurement to obtain density. The sensor exploits wavelength-modulation spectroscopy with second-harmonic detection (WMS-2f) for large signal-to-noise ratios and normalization with the 1f signal for rejection of non-absorption related transmission fluctuations. The sensor line-of-sight is translated both vertically and horizontally across the test section for spatially-resolved measurements. Time-resolved measurements of mass flux are used to assess the stability of flow conditions produced by the facility. Measurements of mass flux are within 1.5% of the value obtained using a facility predictive code. The distortion of the WMS lineshape caused by boundary layers along the laser line-of-sight is examined and the subsequent effect on the measured velocity is discussed. A method for correcting measured velocities for flow non-uniformities is introduced and application of this correction brings measured velocities within 4 m/s of the predicted value in a 1630 m/s flow.

  1. Frequency lock of a dye laser emission on iron atomic line top

    International Nuclear Information System (INIS)

    Durand, P.

    1995-03-01

    The aim of this thesis is to realize a frequency lock of a dye laser emission on iron atomic line top. To reach that goal, the author first presents the calculation of atomic vapour density by means of laser absorption ratio measure and studies the dye laser working. It is then necessary to find a device giving the required precision on the frequency of the absorption line choosen. It is obtained thanks to the atomic line reconstitution by optogalvanic effect which gives the reference. Besides, the author presents the necessity of a laser emission power regulation which is obtained thanks to a device including an acoustic and optic modulator. A reliable and accurate captor is choosen and adjusted testing various hollow cathode lamps. The method to obtain the frequency lock of laser emission on iron atomic line top is described. (TEC). 18 refs., 64 figs

  2. Trident: A Universal Tool for Generating Synthetic Absorption Spectra from Astrophysical Simulations

    Energy Technology Data Exchange (ETDEWEB)

    Hummels, Cameron B. [TAPIR, California Institute of Technology, Pasadena, CA 91125 (United States); Smith, Britton D. [San Diego Supercomputer Center, University of California, San Diego, CA 92121 (United States); Silvia, Devin W. [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States)

    2017-09-20

    Hydrodynamical simulations are increasingly able to accurately model physical systems on stellar, galactic, and cosmological scales; however, the utility of these simulations is often limited by our ability to directly compare them with the data sets produced by observers: spectra, photometry, etc. To address this problem, we have created trident, a Python-based open-source tool for post-processing hydrodynamical simulations to produce synthetic absorption spectra and related data. trident can (i) create absorption-line spectra for any trajectory through a simulated data set mimicking both background quasar and down-the-barrel configurations; (ii) reproduce the spectral characteristics of common instruments like the Cosmic Origins Spectrograph; (iii) operate across the ultraviolet, optical, and infrared using customizable absorption-line lists; (iv) trace simulated physical structures directly to spectral features; (v) approximate the presence of ion species absent from the simulation outputs; (vi) generate column density maps for any ion; and (vii) provide support for all major astrophysical hydrodynamical codes. trident was originally developed to aid in the interpretation of observations of the circumgalactic medium and intergalactic medium, but it remains a general tool applicable in other contexts.

  3. Trident: A Universal Tool for Generating Synthetic Absorption Spectra from Astrophysical Simulations

    Science.gov (United States)

    Hummels, Cameron B.; Smith, Britton D.; Silvia, Devin W.

    2017-09-01

    Hydrodynamical simulations are increasingly able to accurately model physical systems on stellar, galactic, and cosmological scales; however, the utility of these simulations is often limited by our ability to directly compare them with the data sets produced by observers: spectra, photometry, etc. To address this problem, we have created trident, a Python-based open-source tool for post-processing hydrodynamical simulations to produce synthetic absorption spectra and related data. trident can (I) create absorption-line spectra for any trajectory through a simulated data set mimicking both background quasar and down-the-barrel configurations; (II) reproduce the spectral characteristics of common instruments like the Cosmic Origins Spectrograph; (III) operate across the ultraviolet, optical, and infrared using customizable absorption-line lists; (IV) trace simulated physical structures directly to spectral features; (v) approximate the presence of ion species absent from the simulation outputs; (VI) generate column density maps for any ion; and (vii) provide support for all major astrophysical hydrodynamical codes. trident was originally developed to aid in the interpretation of observations of the circumgalactic medium and intergalactic medium, but it remains a general tool applicable in other contexts.

  4. Trident: A Universal Tool for Generating Synthetic Absorption Spectra from Astrophysical Simulations

    International Nuclear Information System (INIS)

    Hummels, Cameron B.; Smith, Britton D.; Silvia, Devin W.

    2017-01-01

    Hydrodynamical simulations are increasingly able to accurately model physical systems on stellar, galactic, and cosmological scales; however, the utility of these simulations is often limited by our ability to directly compare them with the data sets produced by observers: spectra, photometry, etc. To address this problem, we have created trident, a Python-based open-source tool for post-processing hydrodynamical simulations to produce synthetic absorption spectra and related data. trident can (i) create absorption-line spectra for any trajectory through a simulated data set mimicking both background quasar and down-the-barrel configurations; (ii) reproduce the spectral characteristics of common instruments like the Cosmic Origins Spectrograph; (iii) operate across the ultraviolet, optical, and infrared using customizable absorption-line lists; (iv) trace simulated physical structures directly to spectral features; (v) approximate the presence of ion species absent from the simulation outputs; (vi) generate column density maps for any ion; and (vii) provide support for all major astrophysical hydrodynamical codes. trident was originally developed to aid in the interpretation of observations of the circumgalactic medium and intergalactic medium, but it remains a general tool applicable in other contexts.

  5. Absorption spectrum and absorption cross sections of the 2ν1 band of HO2 between 20 and 760 Torr air in the range 6636 and 6639 cm-1

    Science.gov (United States)

    Assaf, Emmanuel; Liu, Lu; Schoemaecker, Coralie; Fittschen, Christa

    2018-05-01

    The absorption spectrum of HO2 radicals has been measured in the range 6636-6639 cm-1 at several pressures between 20 and 760 Torr of air. Absolute absorption cross sections of the strongest line at around 6638.2 cm-1 have been determined from kinetic measurements, taking advantage of the well known rate constant of the self-reaction. Peak absorption cross sections of 22.6, 19.5, 14.4, 7.88, 5.12 and 3.23 × 10-20 cm2 were obtained at 20, 50, 100, 200, 400 and 760 Torr, respectively. By fitting these data, an empirical expression has been obtained for the absorption cross section of HO2 in the range 20-760 Torr air: σ6638.2cm-1 = 1.18 × 10-20 + (2.64 × 10-19 × (1-exp (-63.1/p (Torr))) cm2.

  6. Modelling ultraviolet-line diagnostics of stars, the ionized and the neutral interstellar medium in star-forming galaxies

    Science.gov (United States)

    Vidal-García, A.; Charlot, S.; Bruzual, G.; Hubeny, I.

    2017-09-01

    We combine state-of-the-art models for the production of stellar radiation and its transfer through the interstellar medium (ISM) to investigate ultraviolet-line diagnostics of stars, the ionized and the neutral ISM in star-forming galaxies. We start by assessing the reliability of our stellar population synthesis modelling by fitting absorption-line indices in the ISM-free ultraviolet spectra of 10 Large Magellanic Cloud clusters. In doing so, we find that neglecting stochastic sampling of the stellar initial mass function in these young (∼10-100 Myr), low-mass clusters affects negligibly ultraviolet-based age and metallicity estimates but can lead to significant overestimates of stellar mass. Then, we proceed and develop a simple approach, based on an idealized description of the main features of the ISM, to compute in a physically consistent way the combined influence of nebular emission and interstellar absorption on ultraviolet spectra of star-forming galaxies. Our model accounts for the transfer of radiation through the ionized interiors and outer neutral envelopes of short-lived stellar birth clouds, as well as for radiative transfer through a diffuse intercloud medium. We use this approach to explore the entangled signatures of stars, the ionized and the neutral ISM in ultraviolet spectra of star-forming galaxies. We find that, aside from a few notable exceptions, most standard ultraviolet indices defined in the spectra of ISM-free stellar populations are prone to significant contamination by the ISM, which increases with metallicity. We also identify several nebular-emission and interstellar-absorption features, which stand out as particularly clean tracers of the different phases of the ISM.

  7. X-ray differential phase-contrast tomographic reconstruction with a phase line integral retrieval filter

    International Nuclear Information System (INIS)

    Fu, Jian; Hu, Xinhua; Li, Chen

    2015-01-01

    We report an alternative reconstruction technique for x-ray differential phase-contrast computed tomography (DPC-CT). This approach is based on a new phase line integral projection retrieval filter, which is rooted in the derivative property of the Fourier transform and counteracts the differential nature of the DPC-CT projections. It first retrieves the phase line integral from the DPC-CT projections. Then the standard filtered back-projection (FBP) algorithms popular in x-ray absorption-contrast CT are directly applied to the retrieved phase line integrals to reconstruct the DPC-CT images. Compared with the conventional DPC-CT reconstruction algorithms, the proposed method removes the Hilbert imaginary filter and allows for the direct use of absorption-contrast FBP algorithms. Consequently, FBP-oriented image processing techniques and reconstruction acceleration softwares that have already been successfully used in absorption-contrast CT can be directly adopted to improve the DPC-CT image quality and speed up the reconstruction

  8. A NON-ISOTHERMAL THEORY FOR INTERPRETING SODIUM LINES IN TRANSMISSION SPECTRA OF EXOPLANETS

    Energy Technology Data Exchange (ETDEWEB)

    Heng, Kevin; Lavie, Baptiste [University of Bern, Physics Institute, Center for Space and Habitability, Sidlerstrasse 5, CH-3012 Bern (Switzerland); Wyttenbach, Aurélien; Ehrenreich, David; Lovis, Christophe [Observatoire de l’Université de Genève, 51 chemin des Maillettes, CH-1290 Sauverny (Switzerland); Sing, David K., E-mail: kevin.heng@csh.unibe.ch [Astrophysics Group, School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom)

    2015-04-10

    We present a theory for interpreting the sodium lines detected in transmission spectra of exoplanetary atmospheres. Previous analyses employed the isothermal approximation and dealt only with the transit radius. By recognizing the absorption depth and the transit radius as being independent observables, we develop a theory for jointly interpreting both quantities, which allows us to infer the temperatures and number densities associated with the sodium lines. We are able to treat a non-isothermal situation with a constant temperature gradient. Our novel diagnostics take the form of simple-to-use algebraic formulae and require measurements of the transit radii (and their corresponding absorption depths) at line center and in the line wing for both sodium lines. We apply our diagnostics to the HARPS data of HD 189733b, confirm the upper atmospheric heating reported by Huitson et al., derive a temperature gradient of 0.4376 ± 0.0154 K km{sup −1}, and find densities ∼1–10{sup 4} cm{sup −3}.

  9. On the possibilities of high-resolution continuum source graphite furnace atomic absorption spectrometry for the simultaneous or sequential monitoring of multiple atomic lines

    International Nuclear Information System (INIS)

    Resano, M.; Rello, L.; Florez, M.; Belarra, M.A.

    2011-01-01

    This paper explores the potential of commercially available high-resolution continuum source graphite furnace atomic absorption spectrometry instrumentation for the simultaneous or sequential monitoring of various atomic lines, in an attempt to highlight the analytical advantages that can be derived from this strategy. In particular, it is demonstrated how i) the monitoring of multiplets may allow for the simple expansion of the linear range, as shown for the measurement of Ni using the triplet located in the vicinity of 234.6 nm; ii) the use of a suitable internal standard may permit improving the precision and help in correcting for matrix-effects, as proved for the monitoring of Ni in different biological samples; iii) direct and multi-element analysis of solid samples may be feasible on some occasions, either by monitoring various atomic lines that are sufficiently close (truly simultaneous monitoring, as demonstrated in the determination of Co, Fe and Ni in NIST 1566a Oyster tissue) or, alternatively, by opting for a selective and sequential atomization of the elements of interest during every single replicate. Determination of Cd and Ni in BCR 679 White cabbage is attempted using both approaches, which permits confirming that both methods can offer very similar and satisfactory results. However, it is important to stress that the second approach provides more flexibility, since analysis is no longer limited to those elements that show very close atomic lines (closer than 0.3 nm in the ultraviolet region) with a sensitivity ratio similar to the concentration ratio of the analytes in the samples investigated.

  10. 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

    2014-08-14

    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. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Absorptive reduction and width narrowing in λ-type atoms confined between two dielectric walls

    International Nuclear Information System (INIS)

    Li Yuanyuan; Hou Xun; Bai Jintao; Yan Junfeng; Gan Chenli; Zhang Yanpeng

    2008-01-01

    This paper investigates the absorptive reduction and the width narrowing of electromagnetically induced transparency (EIT) in a thin vapour film of λ-type atoms confined between two dielectric walls whose thickness is comparable with the wavelength of the probe field. The absorptive lines of the weak probe field exhibit strong reductions and very narrow EIT dips, which mainly results from the velocity slow-down effects and transient behaviour of atoms in a confined system. It is also shown that the lines are modified by the strength of the coupling field and the ratio of L/λ, with L the film thickness and λ the wavelength of the probe field. A simple robust recipe for EIT in a thin medium is achievable in experiment. (general)

  12. The potential of immobilized artificial membrane chromatography to predict human oral absorption.

    Science.gov (United States)

    Tsopelas, Fotios; Vallianatou, Theodosia; Tsantili-Kakoulidou, Anna

    2016-01-01

    The potential of immobilized artificial membrane (IAM) chromatography to estimate human oral absorption (%HOA) was investigated. For this purpose, retention indices on IAM stationary phases reported previously by our group or measured by other authors under similar conditions were used to model %HOA data, compiled from literature sources. Considering the pH gradient in gastrointestinal tract, the highest logkw(IAM) values were considered, obtained either at pH7.4 or 5.5, defined as logkw(IAM)(best). Non linear models were established upon introduction of additional parameters and after exclusion of drugs which are substrates either to efflux or uptake transporters. The best model included Abraham's hydrogen-bond acidity parameter, molecular weight as well as the positively and negatively charged molecular fractions. For reasons of comparison between IAM chromatography and traditional lipophilicity, corresponding models were derived by replacing IAM retention factors with octanol-water distribution coefficients (logD). An overexpression of electrostatic interactions with phosphate anions was observed in the case of IAM retention as expressed by the negative contribution of the positively charged fraction F(+). The same parameter is statistically significant also in the logD model, but with a positive sign, indicating the attraction of basic drugs in the negatively charged inner membrane. To validate the obtained models a blind test set of 22 structurally diverse drugs was used, whose logkw(IAM)(best) values were determined and analyzed in the present study under similar conditions. IAM retention factors were further compared with MDCK cell lines permeability data taken from literature for a set of validation drugs. The overexpression of electrostatic interactions with phosphate anions on IAM surface was also evident in respect to MDCK permeability. In contrast to the clear classification between drugs with high and poor (or intermediate) absorption provided by MDCK

  13. X-ray/UV Observing Campaign on the Mrk 279 AGN Outflow: A Global Fitting Analysis of the UV Absorption

    Energy Technology Data Exchange (ETDEWEB)

    Gabel, J.

    2005-03-17

    We present an analysis of the intrinsic UV absorption in the Seyfert 1 galaxy Mrk 279 based on simultaneous long observations with the ''Hubble Space Telescope'' (41 ks) and the ''Far Ultraviolet Spectroscopic Explorer'' (91 ks). To extract the line-of-sight covering factors and ionic column densities, we separately fit two groups of absorption lines: the Lyman series and the CNO lithium-like doublets. For the CNO doublets we assume that all three ions share the same covering factors. The fitting method applied here overcomes some limitations of the traditional method using individual doublet pairs; it allows for the treatment of more complex, physically realistic scenarios for the absorption-emission geometry and eliminates systematic errors that we show are introduced by spectral noise. We derive velocity-dependent solutions based on two models of geometrical covering--a single covering factor for all background emission sources, and separate covering factors for the continuum and emission lines. Although both models give good statistical fits to the observed absorption, we favor the model with two covering factors because: (a) the best-fit covering factors for both emission sources are similar for the independent Lyman series and CNO doublet fits; (b) the fits are consistent with full coverage of the continuum source and partial coverage of the emission lines by the absorbers, as expected from the relative sizes of the nuclear emission components; and (c) it provides a natural explanation for variability in the Lya absorption detected in an earlier epoch. We also explore physical and geometrical constraints on the outflow from these results.

  14. UV laser long-path absorption spectroscopy

    Science.gov (United States)

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

    1994-01-01

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

  15. Electromagnetic-radiation absorption by water.

    Science.gov (United States)

    Lunkenheimer, P; Emmert, S; Gulich, R; Köhler, M; Wolf, M; Schwab, M; Loidl, A

    2017-12-01

    Why does a microwave oven work? How does biological tissue absorb electromagnetic radiation? Astonishingly, we do not have a definite answer to these simple questions because the microscopic processes governing the absorption of electromagnetic waves by water are largely unclarified. This absorption can be quantified by dielectric loss spectra, which reveal a huge peak at a frequency of the exciting electric field of about 20 GHz and a gradual tailing off toward higher frequencies. The microscopic interpretation of such spectra is highly controversial and various superpositions of relaxation and resonance processes ascribed to single-molecule or molecule-cluster motions have been proposed for their analysis. By combining dielectric, microwave, THz, and far-infrared spectroscopy, here we provide nearly continuous temperature-dependent broadband spectra of water. Moreover, we find that corresponding spectra for aqueous solutions reveal the same features as pure water. However, in contrast to the latter, crystallization in these solutions can be avoided by supercooling. As different spectral contributions tend to disentangle at low temperatures, this enables us to deconvolute them when approaching the glass transition under cooling. We find that the overall spectral development, including the 20 GHz feature (employed for microwave heating), closely resembles the behavior known for common supercooled liquids. Thus water's absorption of electromagnetic waves at room temperature is not unusual but very similar to that of glass-forming liquids at elevated temperatures, deep in the low-viscosity liquid regime, and should be interpreted along similar lines.

  16. Electromagnetic-radiation absorption by water

    Science.gov (United States)

    Lunkenheimer, P.; Emmert, S.; Gulich, R.; Köhler, M.; Wolf, M.; Schwab, M.; Loidl, A.

    2017-12-01

    Why does a microwave oven work? How does biological tissue absorb electromagnetic radiation? Astonishingly, we do not have a definite answer to these simple questions because the microscopic processes governing the absorption of electromagnetic waves by water are largely unclarified. This absorption can be quantified by dielectric loss spectra, which reveal a huge peak at a frequency of the exciting electric field of about 20 GHz and a gradual tailing off toward higher frequencies. The microscopic interpretation of such spectra is highly controversial and various superpositions of relaxation and resonance processes ascribed to single-molecule or molecule-cluster motions have been proposed for their analysis. By combining dielectric, microwave, THz, and far-infrared spectroscopy, here we provide nearly continuous temperature-dependent broadband spectra of water. Moreover, we find that corresponding spectra for aqueous solutions reveal the same features as pure water. However, in contrast to the latter, crystallization in these solutions can be avoided by supercooling. As different spectral contributions tend to disentangle at low temperatures, this enables us to deconvolute them when approaching the glass transition under cooling. We find that the overall spectral development, including the 20 GHz feature (employed for microwave heating), closely resembles the behavior known for common supercooled liquids. Thus water's absorption of electromagnetic waves at room temperature is not unusual but very similar to that of glass-forming liquids at elevated temperatures, deep in the low-viscosity liquid regime, and should be interpreted along similar lines.

  17. Steep Hard-X-ray Spectra Indicate Extremely High Accretion Rates in Weak Emission-Line Quasars

    Science.gov (United States)

    Marlar, Andrea; Shemmer, Ohad; Anderson, Scott F.; Brandt, W. Niel; Diamond-Stanic, Aleksandar M.; Fan, Xiaohui; Luo, Bin; Plotkin, Richard; Richards, Gordon T.; Schneider, Donald P.; Wu, Jianfeng

    2018-06-01

    We present XMM-Newton imaging spectroscopy of ten weak emission-line quasars (WLQs) at 0.928 ≤ z ≤ 3.767, six of which are radio quiet and four which are radio intermediate. The new X-ray data enabled us to measure the hard-X-ray power-law photon index (Γ) in each source with relatively high accuracy. These measurements allowed us to confirm previous reports that WLQs have steeper X-ray spectra, therefore indicating higher accretion rates with respect to "typical" quasars. A comparison between the Γ values of our radio-quiet WLQs and those of a carefully-selected, uniform sample of 84 quasars shows that the first are significantly higher, at the ≥ 3σ level. Collectively, the four radio-intermediate WLQs have lower Γ values with respect to the six radio-quiet WLQs, as may be expected if the spectra of the first group are contaminated by X-ray emission from a jet. These results suggest that, in the absence of significant jet emission along our line of sight, WLQs constitute the extreme high end of the accretion rate distribution in quasars. We detect soft excess emission in our lowest-redshift radio-quiet WLQ, in agreement with previous findings suggesting that the prominence of this feature is associated with a high accretion rate. We have not detected signatures of Compton reflection, Fe Kα lines, or strong variability between two X-ray epochs in any of our WLQs.

  18. 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

  19. Molecular line parameters for the atmospheric trace molecule spectroscopy experiment

    Science.gov (United States)

    Brown, L. R.; Farmer, C. B.; Toth, R. A.; Rinsland, Curtis P.

    1987-01-01

    During its first mission in 1985 onboard Spacelab 3, the ATMOS (atmospheric trace molecule spectroscopy) instrument, a high speed Fourier transform spectrometer, produced a large number of high resolution infrared solar absorption spectra recorded in the occultation mode. The analysis and interpretation of these data in terms of composition, chemistry, and dynamics of the earth's upper atmosphere required good knowledge of the molecular line parameters for those species giving rise to the absorptions in the atmospheric spectra. This paper describes the spectroscopic line parameter database compiled for the ATMOS experiment and referenced in other papers describing ATMOS results. With over 400,000 entries, the linelist catalogs parameters of 46 minor and trace species in the 1-10,000/cm region.

  20. The description of compton lines in energy-dispersive x-ray Fluorescence

    International Nuclear Information System (INIS)

    Van Gysel, Mon; Van Espen, P.J.M.

    2001-01-01

    Energy-Dispersive X-Ray Fluorescence (ED-XRF) is a non-destructive technique for the element analysis in a concentration range ppm - % making use of X rays up to 100 keV. Generally, two photon matter interactions occur, respectively absorption and scattering. The absorption of incident photons gives raise to characteristic lines. Scattering gives an incoherent and a coherent line. A Gaussian peak model is adequate to describe the characteristic and coherent scattered lines. Incoherent lines appear as non-Gaussian, broadened peaks. The profile of a Compton peak is complex. It depends on the geometry and the composition of the sample. Especially, when analyzing a low Z matrix; dominant scattering and multiple scattering may cause large interferences. The absence of an appropriate fitting model makes the Compton profile seen as a limiting factor in the evaluation of spectra. An accurate description of incoherent lines should improve quantitative analysis. Therefore, a suitable fitting model, making use of the expertise of non-linear least squares procedures and Monte-Carlo calculations was systematically investigated. The proposed model, containing a modified Gaussian, is tested on experimental data recorded with a HPGe detector

  1. Stellar and interstellar K lines - Gamma Pegasi and iota Herculis.

    Science.gov (United States)

    Hobbs, L. M.

    1973-01-01

    High-resolution scans show that the relatively strong (about 90 mA) K lines of Ca II in the early B stars gamma-Peg and iota-Her are almost entirely stellar in origin, although the latter case includes a small interstellar contribution. Such stellar lines can be of great importance in augmenting the interstellar absorption, up through the earliest of the B stars.

  2. Intestinal absorption and secretion of 65Zn in the rat

    International Nuclear Information System (INIS)

    Methfessel, A.H.; Spencer, H.

    1974-01-01

    A single dose of 65 Zn Cl 2 was given by intubation to the intact rat or was instilled into the lumen of ligated intestinal sacs to determine the absorption, or injected intravenously via the tail vein to determine intestinal secretion of 65 Zn. Results indicated that the small intestine plays a major role in the absorption and secretion of zinc and that aging decreases the absorption of zinc for the duodenum of the rat

  3. Fluctuations at the blue edge of saturated wind lines in IUE spectra of O-type stars

    Science.gov (United States)

    Owocki, Stanley P.; Fullerton, Alex

    1993-01-01

    We examine basic issues involved in synthesizing resonance-line profiles from 1-D, dynamical models of highly structured hot-star winds. Although these models exhibit extensive variations in density as well as velocity, the density scale length is still typically much greater than the Sobolev length. The line transfer is thus treated using a Sobolev approach, as generalized by Rybicki & Hummer (1978) to take proper account of the multiple Sobolev resonances arising from the nonmonotonic velocity field. The resulting reduced-Lambda-matrix equation describing nonlocal coupling of the source function is solved by iteration, and line profiles and then derived from formal solution integration using this source function. The more appropriate methods that instead use either a stationary or a structured, local source function yield qualitatively similar line-profiles, but are found to violate photon conservation by 10 percent or more. The full results suggest that such models may indeed be able to reproduce naturally some of the qualitative properties long noted in observed UV line profiles, such as discrete absorption components in unsaturated lines, or the blue-edge variability in saturated lines. However, these particular models do not yet produce the black absorption troughs commonly observed in saturated lines, and it seems that this and other important discrepancies (e.g., in acceleration time scale of absorption components) may require development of more complete models that include rotation and other 2-D and/or 3-D effects.

  4. Atomic emission lines in the near ultraviolet; hydrogen through krypton, section 2

    Science.gov (United States)

    Kelly, R. L.

    1979-01-01

    A compilation of spectra from the first 36 elements was prepared from published literature available through October 1977. In most cases, only those lines which were actually observed in emission or absorption are listed. The wavelengths included range from 2000 Angstroms to 3200 Angstroms with some additional lines up to 3500 Angstroms. Only lines of stripped atoms are reported; no molecular bands are included.

  5. Atomic emission lines in the near ultraviolet; hydrogen through krypton, section 1

    Science.gov (United States)

    Kelly, R. L.

    1979-01-01

    A compilation of spectra from the first 36 elements was prepared from published literature available through October 1977. In most cases, only those lines which were actually observed in emission or absorption are listed. The wavelengths included range from 2000 Angstroms to 3200 Angstroms with some additional lines up to 3500 Angstroms. Only lines of stripped atoms are reported; no molecular bands are included.

  6. PROXIMA CENTAURI AS A BENCHMARK FOR STELLAR ACTIVITY INDICATORS IN THE NEAR-INFRARED

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, Paul; Bender, Chad; Mahadevan, Suvrath; Roy, Arpita; Ramsey, Lawrence W. [Department of Astronomy and Astrophysics, The Pennsylvania State University University Park, PA (United States)

    2016-12-01

    A new generation of dedicated Doppler spectrographs will attempt to detect low-mass exoplanets around mid- to late M stars at near-infrared (NIR) wavelengths, where those stars are brightest and have the most Doppler information content. A central requirement for the success of these instruments is to properly measure the component of radial velocity (RV) variability contributed by stellar magnetic activity and to account for it in exoplanet models of RV data. The wavelength coverage for many of these new instruments will not include the Ca ii H and K or H α  lines, the most frequently used absorption-line tracers of magnetic activity. Thus, it is necessary to define and characterize NIR activity indicators for mid- to late M stars in order to provide simultaneous activity metrics for NIR RV data. We have used the high-cadence UVES observations of the M5.5 dwarf Proxima Centauri from Fuhrmeister et al. to compare the activity sensitivity of eight NIR atomic lines to that of H α . We find that equivalent-width-type measurements of the NIR K i doublet and the Ca ii NIR triplet are excellent proxies for the canonical optical tracers. The Ca ii triplet will be acquired by most of the new and upcoming NIR Doppler spectrographs, offering a common, reliable indicator of activity.

  7. A Path Loss Model for Non-Line-of-Sight Ultraviolet Multiple Scattering Channels

    Directory of Open Access Journals (Sweden)

    Sadler BrianM

    2010-01-01

    Full Text Available An ultraviolet (UV signal transmission undergoes rich scattering and strong absorption by atmospheric particulates. We develop a path loss model for a Non-Line-of-Sight (NLOS link. The model is built upon probability theory governing random migration of photons in free space, undergoing scattering, in terms of angular direction and distance. The model analytically captures the contributions of different scattering orders. Thus it relaxes the assumptions of single scattering theory and provides more realistic results. This allows us to assess the importance of high-order scattering, such as in a thick atmosphere environment, where short range NLOS UV communication is enhanced by hazy or foggy weather. By simulation, it is shown that the model coincides with a previously developed Monte Carlo model. Additional numerical examples are presented to demonstrate the effects of link geometry and atmospheric conditions. The results indicate the inherent tradeoffs in beamwidth, pointing angles, range, absorption, and scattering and so are valuable for NLOS communication system design.

  8. Microwave heating behavior and microwave absorption properties of barium titanate at high temperatures

    Directory of Open Access Journals (Sweden)

    K. Kashimura

    2016-06-01

    Full Text Available The temperature dependence of the microwave absorption behavior of BaTiO3 particles was investigated over various frequencies and temperatures of 25-1000 ∘C. First, using both the coaxial transmission line method and the cavity perturbation method by a network analyzer, the real and imaginary parts of the relative permittivity of BaTiO3 ( ε r ′ and ε r ″ , respectively were measured, in order to improve the reliability of the data obtained at 2.45 GHz. The imaginary parts of the relative permittivity as measured by the two methods were explored by their heating behaviors. Furthermore, the temperature dependence of the microwave absorption behavior of BaTiO3 particles was investigated for frequencies of 2.0-13.5 GHz and temperatures of 25-1000 ∘C using the coaxial transmission line method.

  9. 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.

  10. Compressed shell conditions extracted from spectroscopic analysis of Ti K-shell absorption spectra with evaluation of line self-emission

    Energy Technology Data Exchange (ETDEWEB)

    Johns, H. M.; Mancini, R. C.; Hakel, P.; Nagayama, T. [Physics Department, University of Nevada, Reno, 1664 N. Virginia St., Reno, Nevada 89557 (United States); Smalyuk, V. A.; Regan, S. P.; Delettrez, J. [Laboratory for Laser Energetics, University of Rochester, 250 E. River Road, Rochester, New York 14623 (United States)

    2014-08-15

    Ti-doped tracer layers embedded in the shell at varying distances from the fuel-shell interface serve as a spectroscopic diagnostic for direct-drive experiments conducted at OMEGA. Detailed modeling of Ti K-shell absorption spectra produced in the tracer layer considers n = 1–2 transitions in F- through Li-like Ti ions in the 4400–4800 eV range, both including and excluding line self-emission. Testing the model on synthetic spectra generated from 1-D LILAC hydrodynamic simulations reveals that the model including self-emission best reproduces the simulation, while the model excluding self-emission overestimates electron temperature T{sub e} and density N{sub e} to a higher degree for layers closer to the core. The prediction of the simulation that the magnitude of T{sub e} and duration of Ti absorption will be strongly tied to the distance of the layer from the core is consistent with the idea that regions of the shell close to the core are more significantly heated by thermal transport out of the hot dense core, but more distant regions are less affected by it. The simulation predicts more time variation in the observed T{sub e}, N{sub e} conditions in the compressed shell than is observed in the experiment, analysis of which reveals conditions remain in the range T{sub e} = 400–600 eV and N{sub e} = 3.0–10.0 × 10{sup 24} cm{sup −3} for all but the most distant Ti-doped layer, with error bars ∼5% T{sub e} value and ∼10% N{sub e} on average. The T{sub e}, N{sub e} conditions of the simulation lead to a greater degree of ionization for zones close to the core than occurs experimentally, and less ionization for zones far from the core.

  11. The distribution of absorptive power dissipation in irradiated nanoparticulate system

    International Nuclear Information System (INIS)

    Li, Jiayu; Yang, Jian; Gu, Xiaobing

    2016-01-01

    The knowledge of local radiant absorption is important to the nanostructure optimization, it is beneficial to the applications in energy harvesting, optical heating, photocatalysis, etc. In this paper, FDTD model is constructed for the distribution of absorptive power dissipation in irradiated nanoparticulate system. The theoretical model extended from Mie theory is used to examine the FDTD model, the parameters and conditions set for FDTD simulation are confirmed based on the comparison. Then, the influence of Ag nanoparticle on the absorptive properties of nearby TiO_2 nanoparticle is investigated by FDTD simulation at the wavelength of 0.25 μm. It is indicated that suitable distance between TiO_2 and Ag particles is beneficial to the spectral radiant absorption of TiO_2 particle. Considering the agglomeration of nanoparticles and the oxidation at the TiO_2–Ag interface, the Ag core coated with Al_2O_3 shell is suggested, and the simulated results indicated that the shell thickness and the Ag core size need to be optimized for enhancing the radiant absorption of TiO_2 particle. - Highlights: • The absorptive power distribution in nanoparticulate system is simulated by FDTD. • FDTD simulation is compared with theoretical model extended from Mie theory. • The parameters and conditions are confirmed based on the comparison. • The influence of Ag nanoparticle on nearby TiO_2 particle's absorption is analyzed.

  12. Observation of soft x-ray radiation from Heliotron E plasmas by the absorption method for the measurement of electron temperatures

    International Nuclear Information System (INIS)

    Kaneko, H.; Tohda, T.; Iiyoshi, A.

    1989-01-01

    An absorption method of soft x ray is applied to Heliotron E plasmas for measurement of the electron temperature. Nitrogen gas is used as an absorber for convenience, owing to its accurate, uniform, and easily controllable density. The general feature of the absorption method for measurement of the electron temperature is discussed using a model with two parameters: the generalized thickness of the absorber and the electron temperature. The energy resolution of this method is not sufficient as a general method for spectral analysis. Hence, it is necessary to assume in advance such a model spectrum as consists of bremsstrahlung, recombination radiation, and impurity line radiation. Since the spectrum is always assumed before the analysis, we should try to find the origins of deformation of the energy spectrum and to correct the contribution. The effect of line emission from impurity ions to the estimated electron temperature is evaluated as a function of the electron temperature and the energy of the line relative to the generalized absorber thickness used in the measurement. An actual spectrum is measured by a pulse-height analysis (PHA) of the soft x ray. The one clear line, from chlorine, is not significant in the present determination of the electron temperature by the absorption method. Another possible line from iron at energy less than 1 keV is included in the analysis. Using a convenient method for determination of local emissivity from a chord-integrated emissivity, the electron temperature is determined from the local emissivity. The observed broad electron-temperature profile might be an artifact due to recombination radiation of the highly ionized ion diffused out of the hot core of the plasma. It is confirmed that the absorption method gives absolute measurement of the electron temperature at the plasma center, when additional information on impurity lines are given by PHA

  13. The origin of cholesterol in chyle demonstrated by nuclear indicator methods

    International Nuclear Information System (INIS)

    Vyas, M.

    1962-01-01

    In order to obtain information about the mechanism of the intestinal absorption of cholesterol, rats having a lymphatic abdominal fistula are used. The animals receive either 4- 14 C- cholesterol subcutaneously or orally, or the 1- 14 C acetate. The study of the specific radio-activities of the cholesterol in chyle, in serum, in the lining, and in the intestinal contents makes it possible to define the roles played by the transfer cholesterol from the serum, by the cholesterol synthesised intestinally, and by the absorption cholesterol, in the formations of the lymph and of the chylomicrons. A new theory is proposed for the mechanism of cholesterol absorption. (author) [fr

  14. On-Line Impact Load Identification

    Directory of Open Access Journals (Sweden)

    Krzysztof Sekuła

    2013-01-01

    Full Text Available The so-called Adaptive Impact Absorption (AIA is a research area of safety engineering devoted to problems of shock absorption in various unpredictable scenarios of collisions. It makes use of smart technologies (systems equipped with sensors, controllable dissipaters and specialised tools for signal processing. Examples of engineering applications for AIA systems are protective road barriers, automotive bumpers or adaptive landing gears. One of the most challenging problems for AIA systems is on-line identification of impact loads, which is crucial for introducing the optimum real-time strategy of adaptive impact absorption. This paper presents the concept of an impactometer and develops the methodology able to perform real-time impact load identification. Considered dynamic excitation is generated by a mass M1 impacting with initial velocity V0. An analytical formulation of the problem, supported with numerical simulations and experimental verifications is presented. Two identification algorithms based on measured response of the impacted structure are proposed and discussed. Finally, a concept of the AIA device utilizing the idea of impactometer is briefly presented.

  15. 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.

  16. Light absorption and scattering mechanisms in laser fusion plasmas

    International Nuclear Information System (INIS)

    Barnes, C.; Estabrook, K.G.; Kruer, W.L.; Langdon, A.B.; Lasinski, B.F.; Max, C.E.; Randall, C.; Thomson, J.J.

    1977-01-01

    The picture of laser light absorption and scattering which is emerging from theory and computer simulation studies of laser-plasma interactions is described. On the subject of absorption, we discuss theoretical and experimental evidence that resonance absorption in a steepened density profile is a dominant absorption mechanism. Recent work also indicates the presence of critical surface ripples, which we study using two and three dimensional computer simulations. Predictions of hot electron spectra due to resonance absorption are described, as are effects of plasma outflow. We then discuss two regimes where stimulated scattering may occur. Brillouin scattering is expected in the underdense target blow-off, for long laser pulses, and is limited by ion heating. Raman scattering in the background gas of a reactor target chamber is predicted to be at most a 10 percent effect for 1 μm lasers

  17. Influence of laser beam profile on electromagnetically induced absorption

    International Nuclear Information System (INIS)

    Cuk, S. M.; Radonjic, M.; Krmpot, A. J.; Nikolic, S. N.; Grujic, Z. D.; Jelenkovic, B. M.

    2010-01-01

    We compared, experimentally and theoretically, Hanle electromagnetically induced absorption (EIA) obtained using Gaussian and Π-shaped laser beams 3 mm in diameter. The study was done by measuring the transmission of a laser locked to the F g =2→F e =3 transition at the D 2 line of 87 Rb in a vacuum cell. EIA linewidths obtained for the two laser profiles were significantly different in the range of laser intensities 1-4 mW/cm 2 . EIA with the Π-shaped laser beam has a broad intensity maximum and linewidths larger than those obtained with the Gaussian beam profile. We also studied Hanle EIA by measuring the transmission of selected segments of the entire laser beam by placing a small movable aperture in front of the detector. Waveforms so obtained in Hanle EIA resonances were strongly influenced both by the radial distance of the transmitted segment from the beam center and by the radial profile of the laser beam. We show that outer regions of Gaussian beam, and central regions of the Π-shaped beam generate the narrowest lines. The different behaviors of EIA owing to different beam profiles revealed by both theory and experiment indicate the importance of the radial profile of the laser beam for proper modeling of coherent effects in alkali metal vapors.

  18. Absorption of orally administered 65Zn by normal human subjects

    International Nuclear Information System (INIS)

    Aamodt, R.L.; Rumble, W.F.; Johnston, G.S.; Markley, E.J.; Henkin, R.I.

    1981-01-01

    Despite studies by several investigators of human gastrointestinal 65Zn absorption, implications of these data for evaluation of functional zinc status are unclear because limited numbers of normal subjects have been studied. To evaluated zinc absorption in normal humans, 75 subjects (31 women, 44 men, ages 18 to 84 yr) were given 10 micro Ci carrier-free 65Zn orally after an overnight fast. Absorption calculated from total body retention measured 7, 14, and 21 days after administration of tracer was 65 +/- 11% (mean +/- 1 SD), range from 40 to 86%. Comparison of these results with those for patients with a variety of diseases indicate that patients exhibit a wider range of absorption and, in four of six studies patients exhibit decreased mean zinc absorption. These results of gastrointestinal zinc absorption in a large number of normal humans offer a basis for a clearer comparison with data from patients who exhibit abnormalities of zinc absorption

  19. Mooring Line Damping Estimation for a Floating Wind Turbine

    Directory of Open Access Journals (Sweden)

    Dongsheng Qiao

    2014-01-01

    Full Text Available The dynamic responses of mooring line serve important functions in the station keeping of a floating wind turbine (FWT. Mooring line damping significantly influences the global motions of a FWT. This study investigates the estimation of mooring line damping on the basis of the National Renewable Energy Laboratory 5 MW offshore wind turbine model that is mounted on the ITI Energy barge. A numerical estimation method is derived from the energy absorption of a mooring line resulting from FWT motion. The method is validated by performing a 1/80 scale model test. Different parameter changes are analyzed for mooring line damping induced by horizontal and vertical motions. These parameters include excitation amplitude, excitation period, and drag coefficient. Results suggest that mooring line damping must be carefully considered in the FWT design.

  20. Mooring line damping estimation for a floating wind turbine.

    Science.gov (United States)

    Qiao, Dongsheng; Ou, Jinping

    2014-01-01

    The dynamic responses of mooring line serve important functions in the station keeping of a floating wind turbine (FWT). Mooring line damping significantly influences the global motions of a FWT. This study investigates the estimation of mooring line damping on the basis of the National Renewable Energy Laboratory 5 MW offshore wind turbine model that is mounted on the ITI Energy barge. A numerical estimation method is derived from the energy absorption of a mooring line resulting from FWT motion. The method is validated by performing a 1/80 scale model test. Different parameter changes are analyzed for mooring line damping induced by horizontal and vertical motions. These parameters include excitation amplitude, excitation period, and drag coefficient. Results suggest that mooring line damping must be carefully considered in the FWT design.

  1. Measurement of uranium concentration by molecular absorption spectrophotometry by means optical fibers

    International Nuclear Information System (INIS)

    Gauna, Alberto C.; Pascale, Ariel A.

    1996-01-01

    An on-line method for measuring the concentration of uranium in uranyl nitrate-nitric acid aqueous solutions is described. The method is based on molecular absorption spectrophotometry with transmission of light by means of optical fibers. It is ideally suited for control and processes development applications. (author)

  2. Graphical expression of thermodynamic characteristics of absorption process in ammonia-water system

    Directory of Open Access Journals (Sweden)

    Fortelný Zdeněk

    2012-04-01

    Full Text Available The adiabatic sorption is very interesting phenomenon that occurs when vapor of refrigerant is in contact with unsaturated liquid absorbent-refrigerant mixture and exchange of heat is forbid between the system and an environment. This contribution introduces new auxiliary lines that enable correct position determination of the adiabatic sorption process in the p-T-x diagram of ammoniawater system. The presented auxiliary lines were obtained from common functions for fast calculation of water-ammonia system properties. Absorption cycles designers often utilize p-t-x diagrams of working mixtures for first suggestion of new absorption cycles. The p-t-x diagrams enable fast correct determination of saturate states of liquid (and gaseous mixtures of refrigerants and absorbents. The working mixture isn’t only at saturated state during a real working cycle. If we know pressure and temperature of an unsaturated mixture, exact position determination is possible in the p-t-x diagrams too.

  3. Statistical evidences of absorption at high latitudes

    International Nuclear Information System (INIS)

    Fesenko, B.I.

    1980-01-01

    Evidences are considered which indicate to the significant effect of the irregular interstellar absorption at high latitudes b. The number density of faint galaxies grows with the increasing |b| even at the values of |b| exceeding 50 deg. The effects of interstellar medium are traced even in the directions of the stars and globular clusters with very low values of the colour excess. The coefficient of absorption, Asub(B)=0.29+-0.05, was estimated from the colours of the bright E-galaxies [ru

  4. Absorption spectrum of a V-type three-level atom driven by a coherent field

    International Nuclear Information System (INIS)

    Dong Po; Tang, S.H.

    2002-01-01

    We examine the absorption of a weak probe beam by a laser driven V-type atom with a pair of closely lying excited levels, where both the driving and probe lasers interact simultaneously with the two transitions. The effects of quantum interference among decay channels on the absorption spectra are also investigated. We introduce dipole moments in the dressed-state representation and the Hamiltonian in terms of the dressed states describing the interaction between the probe and the atom. In the degenerate case, features similar to that of a driven two-level atomic system are found due to some dark transitions in the spontaneous emission and the fact that the probe beam only detects certain transitions. In the nondegenerate case, the absorption spectrum is strongly influenced by the degree of quantum interference, resulting in different line shapes for emission peaks, absorption peaks, and dispersionlike profiles. The effect of probe polarization on the absorption spectrum is also investigated

  5. A novel 3D absorption correction method for quantitative EDX-STEM tomography

    International Nuclear Information System (INIS)

    Burdet, Pierre; Saghi, Z.; Filippin, A.N.; Borrás, A.; Midgley, P.A.

    2016-01-01

    This paper presents a novel 3D method to correct for absorption in energy dispersive X-ray (EDX) microanalysis of heterogeneous samples of unknown structure and composition. By using STEM-based tomography coupled with EDX, an initial 3D reconstruction is used to extract the location of generated X-rays as well as the X-ray path through the sample to the surface. The absorption correction needed to retrieve the generated X-ray intensity is then calculated voxel-by-voxel estimating the different compositions encountered by the X-ray. The method is applied to a core/shell nanowire containing carbon and oxygen, two elements generating highly absorbed low energy X-rays. Absorption is shown to cause major reconstruction artefacts, in the form of an incomplete recovery of the oxide and an erroneous presence of carbon in the shell. By applying the correction method, these artefacts are greatly reduced. The accuracy of the method is assessed using reference X-ray lines with low absorption. - Highlights: • A novel 3D absorption correction method is proposed for 3D EDX-STEM tomography. • The absorption of X-rays along the path to the surface is calculated voxel-by-voxel. • The method is applied on highly absorbed X-rays emitted from a core/shell nanowire. • Absorption is shown to cause major artefacts in the reconstruction. • Using the absorption correction method, the reconstruction artefacts are greatly reduced.

  6. A novel 3D absorption correction method for quantitative EDX-STEM tomography

    Energy Technology Data Exchange (ETDEWEB)

    Burdet, Pierre, E-mail: pierre.burdet@a3.epfl.ch [Department of Materials Science and Metallurgy, University of Cambridge, Charles Babbage Road 27, Cambridge CB3 0FS, Cambridgeshire (United Kingdom); Saghi, Z. [Department of Materials Science and Metallurgy, University of Cambridge, Charles Babbage Road 27, Cambridge CB3 0FS, Cambridgeshire (United Kingdom); Filippin, A.N.; Borrás, A. [Nanotechnology on Surfaces Laboratory, Materials Science Institute of Seville (ICMS), CSIC-University of Seville, C/ Americo Vespucio 49, 41092 Seville (Spain); Midgley, P.A. [Department of Materials Science and Metallurgy, University of Cambridge, Charles Babbage Road 27, Cambridge CB3 0FS, Cambridgeshire (United Kingdom)

    2016-01-15

    This paper presents a novel 3D method to correct for absorption in energy dispersive X-ray (EDX) microanalysis of heterogeneous samples of unknown structure and composition. By using STEM-based tomography coupled with EDX, an initial 3D reconstruction is used to extract the location of generated X-rays as well as the X-ray path through the sample to the surface. The absorption correction needed to retrieve the generated X-ray intensity is then calculated voxel-by-voxel estimating the different compositions encountered by the X-ray. The method is applied to a core/shell nanowire containing carbon and oxygen, two elements generating highly absorbed low energy X-rays. Absorption is shown to cause major reconstruction artefacts, in the form of an incomplete recovery of the oxide and an erroneous presence of carbon in the shell. By applying the correction method, these artefacts are greatly reduced. The accuracy of the method is assessed using reference X-ray lines with low absorption. - Highlights: • A novel 3D absorption correction method is proposed for 3D EDX-STEM tomography. • The absorption of X-rays along the path to the surface is calculated voxel-by-voxel. • The method is applied on highly absorbed X-rays emitted from a core/shell nanowire. • Absorption is shown to cause major artefacts in the reconstruction. • Using the absorption correction method, the reconstruction artefacts are greatly reduced.

  7. Study of thermal treatments and irradiation on natural amethyst by optical absorption

    International Nuclear Information System (INIS)

    Dotto, C.T.

    1987-01-01

    Thermal treatment effects on the samples of amethyst from Minas Gerais and Rio Grande do Sul, through optical absorption measurements, are studied. The effects of cobalt 60 gama ray radiation on the amethyst from Minas Gerais through optical absorption measurements, are studied. The optical absorption spectra shows a basic line and bands in 10,500 cm -1 (k), in 18,300 cm -1 (θ) and in 28,000 cm -1 (ζ). The correlation between thermal treatment effects and radiation effects shows that the θ and ζ bands belongs to a same center and the k band to another center. The basic line vanishes by thermal treatments at 270 0 C. The analyses of the isothermal treatment decay and dose-curve reveal a complex kinetics, suggesting that the kinetic mechanisms involve the electron (s) and hole (s) migration in the lattice. The amethyst from Minas Gerais after being discolored at 470 0 C and irradiated again shows that the optical absorption bands don't recover the original absorbance, suggesting the existence of iron diffusion mechanisms in the lattice. After being isothermally annealed the amethyst from Rio Grande do Sul above 400 0 C temperature yield a yellow-brown color, probably due to the formation of Fe 2 O 3 precipitate. We suggest the this formation is due to iron diffusion and pre-existent oxygen vacancies. This model is reinforced through the observation the amethyst from Minas Gerais, isothermally treated at 470 0 C in highly reducing, also gets a yellow-brown color. (author) [pt

  8. Determination of Hg(II) in waters by on-line preconcentration using Cyanex 923 as a sorbent - Cold vapor atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Duan Taicheng; Song Xuejie; Xu Jingwei; Guo Pengran; Chen Hangting; Li Hongfei

    2006-01-01

    Using a solid phase extraction mini-column home-made from a neutral extractant Cyanex 923, inorganic Hg could be on-line preconcentrated and simultaneously separated from methyl mercury. The preconcentrated Hg (II) was then eluted with 10% HNO 3 and subsequently reduced by NaBH 4 to form Hg vapor before determination by cold vapor atomic absorption spectrometry (CVAAS). Optimal conditions for and interferences on the Hg preconcentration and measurement were at 1% HCl, for a 25 mL sample uptake volume and a 10 mL min -1 sample loading rate. The detection limit was 0.2 ng L -1 and much lower than that of conventional method (around 15.8 ng L -1 ). The relative standard deviation (RSD) is 1.8% for measurements of 40 ng L -1 of Hg and the linear working curve is from 20 to 2000 ng L -1 (with a correlation coefficient of 0.9996). The method was applied in determination of inorganic Hg in city lake and deep well water (from Changchun, Jilin, China), and recovery test results for both samples were satisfactory

  9. X-ray reflectivity of cobalt and titanium in the vicinity of the Lsub(2,3) absorption edges

    International Nuclear Information System (INIS)

    Bremer, J.; Kaihola, L.; Keski-Kuha, R.

    1980-01-01

    X-ray reflectivity across cobalt and titanium Lsub(2,3) absorption edges was measured as a function of energy by means of continuous radiation from a tungsten anode in a grating spectrometer. The real and imaginary parts of the refractive index were obtained from the absorption curves and an exact Kramers-Kronig analysis. A measured fine structure in the reflected intensities was interpreted as an effect of white lines in the absorption spectra. The x-ray intensity was calculated as a function of energy by means of the Fresnel formula. (author)

  10. On-line preconcentration and determination of mercury in biological and environmental samples by cold vapor-atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Ferrua, N.; Cerutti, S.; Salonia, J.A.; Olsina, R.A.; Martinez, L.D.

    2007-01-01

    An on-line procedure for the determination of traces of total mercury in environmental and biological samples is described. The present methodology combines cold vapor generation associated to atomic absorption spectrometry (CV-AAS) with preconcentration of the analyte on a minicolumn packed with activated carbon. The retained analyte was quantitatively eluted from the minicolumn with nitric acid. After that, volatile specie of mercury was generated by merging the acidified sample and sodium tetrahydroborate(III) in a continuous flow system. The gaseous analyte was subsequently introduced via a stream of Ar carrier into the atomizer device. Optimizations of both, preconcentration and mercury volatile specie generation variables were carried out using two level full factorial design (2 3 ) with 3 replicates of the central point. Considering a sample consumption of 25 mL, an enrichment factor of 13-fold was obtained. The detection limit (3σ) was 10 ng L -1 and the precision (relative standard deviation) was 3.1% (n = 10) at the 5 μg L -1 level. The calibration curve using the preconcentration system for mercury was linear with a correlation coefficient of 0.9995 at levels near the detection limit up to at least 1000 μg L -1 . Satisfactory results were obtained for the analysis of mercury in tap water and hair samples

  11. Cosmological implications of the redshift distribution of QSO absorption systems

    International Nuclear Information System (INIS)

    Khare-Joshi, P.; Perry, J.J.

    1982-01-01

    We have used the observational data on QSO absorption redshifts, as compiled by Perry, Burbidge and Burbidge (1978) (hereafter PB 2 ), Drew (1978) and Weyman et al. (1979) (hereafter W 2 PT), to study various selection effects likely to affect the distribution of absorption redshifts and, then to determine the probable number distribution of absorbers per redshift interval of 0.1, as a function of z. The distribution obtained, assuming all the observed absorption to be intervening, is found to be statistically incompatible with the redshift distribution of galaxies with constant cross-section for any Friedman cosmology with zero cosmological constant and q 0 >= 0. Therefore, in order to eliminate the absorption systems which are plausibly intrinsic, we have applied the criterion suggested by W 2 PT and by the analysis of the distribution of absorption systems as a function of the relative velocity between the emitting and the absorbing gas, for the PB 2 data set; to wit, we have analysed the distributions obtained by assuming that those systems with relative velocity greater than 0.02 c, 0.02 c but not equal to 0.1 c to 0.11 c and 0.06 c respectively, or those systems without O VI and N V lines, are produced by the intervening galaxies. The results are discussed. (author)

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

    Science.gov (United States)

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

    2009-01-01

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

  13. Spatial dispersion effects in spectral line broadening by pressure. I. The Bouguer Law and absorption coefficient

    International Nuclear Information System (INIS)

    Cherkasov, M.R.

    1995-01-01

    Based on the general principles of semiclassical electrodynamics, the Bouguer law is derived, and the expression for the absorption coefficient is obtained, formally including all effects related to the phenomenon of spatial dispersion

  14. Polarization of submillimetre lines from interstellar medium

    Science.gov (United States)

    Zhang, Heshou; Yan, Huirong

    2018-04-01

    Magnetic fields play important roles in many astrophysical processes. However, there is no universal diagnostic for the magnetic fields in the interstellar medium (ISM) and each magnetic tracer has its limitation. Any new detection method is thus valuable. Theoretical studies have shown that submillimetre fine-structure lines are polarized due to atomic alignment by ultraviolet photon-excitation, which opens up a new avenue to probe interstellar magnetic fields. We will, for the first time, perform synthetic observations on the simulated three-dimensional ISM to demonstrate the measurability of the polarization of submillimetre atomic lines. The maximum polarization for different absorption and emission lines expected from various sources, including star-forming regions are provided. Our results demonstrate that the polarization of submillimetre atomic lines is a powerful magnetic tracer and add great value to the observational studies of the submilimetre astronomy.

  15. 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.

  16. Use of absorption spectroscopy for refined petroleum product discrimination

    Science.gov (United States)

    Short, Michael

    1991-07-01

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

  17. Supporting Structure of the LSD Wave in an Energy Absorption Perspective

    International Nuclear Information System (INIS)

    Fukui, Akihiro; Hatai, Keigo; Cho, Shinatora; Arakawa, Yoshihiro; Komurasaki, Kimiya

    2008-01-01

    In Repetitively Pulsed (RP) Laser Propulsion, laser energy irradiated to a vehicle is converted to blast wave enthalpy during the Laser Supported Detonation (LSD) regime. Based on the measured post-LSD electron number density profiles by two-wavelength Mach Zehnder interferometer in a line-focusing optics, electron temperature and absorption coefficient were estimated assuming Local Thermal Equilibrium. A 10J/pulse CO 2 laser was used. As a result, laser absorption was found completed in the layer between the shock wave and the electron density peak. Although the LSD-termination timing was not clear from the shock-front/ionization-front separation in the shadowgraph images, there observed drastic changes in the absorption layer thickness from 0.2 mm to 0.5 mm and in the peak heating rate from 12-17x10 13 kW/m 3 to 5x10 13 kW/m 3 at the termination

  18. Direct atomic absorption determination of silicon in metallic niobium

    International Nuclear Information System (INIS)

    Blinova, Eh.S.; Guzeev, I.D.; Nedler, V.V.; Khokhrin, V.M.

    1984-01-01

    Consideration is being given to realization of the basic advantage of non-flame atomizer-analysis of directly solid samples-for silicon determination in niobium for the content of the first one of less than 1x10 -3 mass %. Analysis technique is described. Diagrams of the dependences of atomic silicon absorption in graphite cells of usual type as well as lined by tungsten carbide and atomic silicon absorption on the value of niobium weighed amount are presented. It is shown that Si determination in metallic niobium according to aqueous reference solutions results in understatement of results 2.4 times. The optimal conditions for Si determination in niobium are the following: 2400 deg C temperature, absence of carbon and oxygen. Different niobium specimens with the known silicon content were used as reference samples

  19. Enhanced index and negative dispersion without absorption in driven cascade media

    International Nuclear Information System (INIS)

    Hu Xiangming; Xu Jun

    2004-01-01

    In this paper we investigate the dispersive and absorptive properties of a system of three-level cascade atoms driven by a strong coherent field. Three characteristic features are found. First, for the same set of atom-light interaction parameters, the indices of refraction are large at three different frequencies where the absorption vanishes. These three frequencies are determined by the resonance transition frequencies between dressed states produced by the strong driving field. Second, negative dispersion without absorption, which leads to superluminal light propagation, is achievable in the central resonance structure of the dispersion spectrum. Third, the whole absorption spectrum displays, in general, three pairs of absorption peaks and three pairs of gain (negative absorption) peaks. The minimal spacing between dressed states determines whether the outer adjacent gain peaks are separated from each other

  20. Absorption and Transport of Sea Cucumber Saponins from Apostichopus japonicus.

    Science.gov (United States)

    Li, Shuai; Wang, Yuanhong; Jiang, Tingfu; Wang, Han; Yang, Shuang; Lv, Zhihua

    2016-06-17

    The present study is focused on the intestinal absorption of sea cucumber saponins. We determined the pharmacokinetic characteristics and bioavailability of Echinoside A and Holotoxin A₁; the findings indicated that the bioavailability of Holotoxin A₁ was lower than Echinoside A. We inferred that the differences in chemical structure between compounds was a factor that explained their different characteristics of transport across the intestine. In order to confirm the absorption characteristics of Echinoside A and Holotoxin A₁, we examined their transport across Caco-2 cell monolayer and effective permeability by single-pass intestinal perfusion. The results of Caco-2 cell model indicate that Echinoside A is transported by passive diffusion, and not influenced by the exocytosis of P-glycoprotein (P-gp, expressed in the apical side of Caco-2 monolayers as the classic inhibitor). The intestinal perfusion also demonstrated well the absorption of Echinoside A and poor absorption of Holotoxin A₁, which matched up with the result of the Caco-2 cell model. The results demonstrated our conjecture and provides fundamental information on the relationship between the chemical structure of these sea cucumber saponins and their absorption characteristics, and we believe that our findings build a foundation for the further metabolism study of sea cucumber saponins and contribute to the further clinical research of saponins.

  1. Ly α Absorption at Transits of HD 209458b: A Comparative Study of Various Mechanisms Under Different Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Khodachenko, M. L.; Lammer, H.; Kislyakova, K. G.; Fossati, L.; Arkhypov, O. V. [Space Research Institute, Austrian Academy of Sciences, Graz (Austria); Shaikhislamov, I. F.; Berezutsky, A. G.; Miroshnichenko, I. B.; Posukh, V. G. [Institute of Laser Physics SB RAS, Novosibirsk (Russian Federation); Johnstone, C. P., E-mail: maxim.khodachenko@oeaw.ac.at [Department of Astrophysics, University of Vienna (Austria)

    2017-10-01

    To shed more light on the nature of the observed Ly α absorption during transits of HD 209458b and to quantify the major mechanisms responsible for the production of fast hydrogen atoms (the so-called energetic neutral atoms, ENAs) around the planet, 2D hydrodynamic multifluid modeling of the expanding planetary upper atmosphere, which is driven by stellar XUV, and its interaction with the stellar wind has been performed. The model self-consistently describes the escaping planetary wind, taking into account the generation of ENAs due to particle acceleration by the radiation pressure and by the charge exchange between the stellar wind protons and planetary atoms. The calculations in a wide range of stellar wind parameters and XUV flux values showed that under typical Sun-like star conditions, the amount of generated ENAs is too small, and the observed absorption at the level of 6%–8% can be attributed only to the non-resonant natural line broadening. For lower XUV fluxes, e.g., during the activity minima, the number of planetary atoms that survive photoionization and give rise to ENAs increases, resulting in up to 10%–15% absorption at the blue wing of the Ly α line, caused by resonant thermal line broadening. A similar asymmetric absorption can be seen under the conditions realized during coronal mass ejections, when sufficiently high stellar wind pressure confines the escaping planetary material within a kind of bowshock around the planet. It was found that the radiation pressure in all considered cases has a negligible contribution to the production of ENAs and the corresponding absorption.

  2. Rapid accurate analysis of metal (oxide)-on-silica catalysts by atomic absorption spectrometry

    NARCIS (Netherlands)

    Jütte, B.A.H.G.; Heikamp, A.; Agterdenbos, J.

    1979-01-01

    The catalysts, which contain 10–60% copper, chromium, nickel and silicon, are decomposed in sealed Teflon-lined vessels and analyzed by atomic absorption spectrometry. Matrix matching and bracketing standards are applied. The RSD of a single determination is about 1% for all components.

  3. An Intercomparison Study of Two Proximate Damped Lyα Systems with Residual Flux upon the Lyα Absorption Trough toward Quasars

    Science.gov (United States)

    Xie, Xiaoyi; Zhou, Hongyan; Pan, Xiang; Jiang, Peng; Shi, Xiheng; Ji, Tuo; Zhang, Shaohua; Wu, Shengmiao; Zhong, Zhihao

    2018-05-01

    In this paper, we present an intercomparison study of two quasars, SDSS J145618.32+340037.2 and SDSS J215331.50–025514.1, which have proximate damped Lyα systems (PDLAs) with residual flux upon the Lyα absorption trough. Though they both have residual flux as luminous as 1043 erg s‑1, their PDLAs are quite different in, e.g., neutral hydrogen column density, metal line absorption strength, high-ionization absorption lines as well as residual flux strength. For J1456+3400, the H I column density is log(N H I /cm–2) = 20.6 ± 0.2, with z abs = 2.3138, nearly identical to the quasar redshift (z = 2.3142) determined from the [O III] emission line. The metallicity of this system is typical of DLAs and there is high ionization therein, suggesting that the PDLA system is multiphase, putting it in the quasar environment. For J2153–0255, we measure the H I column density to be log(N H I /cm–2) = 21.5 ± 0.1 at z abs = 3.511, slightly redshifted with respect to the quasar (z = 3.490) measured from C III]. The metallicity of this system is quite low and there is a lack of significant high-ionization absorption lines therein, suggesting that the system is beyond the quasar host galaxy. The residual flux is wide (∼1000 km s‑1) in J1456, with a significance of ∼8σ, while also wide (∼1500 km s‑1) but with a smaller significance of ∼3σ in J2153. Among many explanations, we find that Lyα fuzz or resonant scattering can be used to explain the residual flux in the two sources while partial coverage cannot be excluded for J1456. By comparing these two cases, together with a similar case reported previously, we suggest that the strength of the residual flux is related to properties such as metallicity and high-ionization absorption lines of PDLAs. The residual flux recorded upon the PDLA absorption trough opens a window for us to see the physical conditions and processes of the quasar environment, and their profile and strength further remind us of their

  4. Trace gas absorption spectroscopy using laser difference-frequency spectrometer for environmental application

    Science.gov (United States)

    Chen, W.; Cazier, F.; Boucher, D.; Tittel, F. K.; Davies, P. B.

    2001-01-01

    A widely tunable infrared spectrometer based on difference frequency generation (DFG) has been developed for organic trace gas detection by laser absorption spectroscopy. On-line measurements of concentration of various hydrocarbons, such as acetylene, benzene, and ethylene, were investigated using high-resolution DFG trace gas spectroscopy for highly sensitive detection.

  5. ORIGINS OF ABSORPTION SYSTEMS OF CLASSICAL NOVA V2659 CYG (NOVA CYG 2014)

    Energy Technology Data Exchange (ETDEWEB)

    Arai, A.; Kawakita, H. [Koyama Astronomical Observatory, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555 (Japan); Shinnaka, Y. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Tajitsu, A., E-mail: arai6a@cc.kyoto-su.ac.jp [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A’ohoku Place, Hilo, Hawaii 96720 (United States)

    2016-10-10

    We report on high-dispersion spectroscopy results of a classical nova V2659 Cyg (Nova Cyg 2014) that are taken 33.05 days after the V -band maximum. The spectrum shows two distinct blueshifted absorption systems originating from H i, Fe ii, Ca ii, etc. The radial velocities of the absorption systems are −620 km s{sup −1}, and −1100 to −1500 km s{sup −1}. The higher velocity component corresponds to the P-Cygni absorption features frequently observed in low-resolution spectra. Much larger numbers of absorption lines are identified at the lower velocity. These mainly originate from neutral or singly ionized Fe-peak elements (Fe i, Ti ii, Cr ii, etc.). Based on the results of our spectroscopic observations, we discuss the structure of the ejecta of V2659 Cyg. We conclude that the low- and high-velocity components are likely to be produced by the outflow wind and the ballistic nova ejecta, respectively.

  6. Associated HI Absorption in the z = 3.4 Radio Galaxy B2 0902 + 343 ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    of star formation (Einsenhardt & Dickinson 1992). The spatial ... on the blue-ward side of the narrow absorption feature has been reported by ..... associated with a merging galaxy located near the hot spot or dwarf galaxy along the line of sight ...

  7. Primary gas thermometry by means of laser-absorption spectroscopy: Determination of the Boltzmann constant

    OpenAIRE

    Casa, G.; Castrillo, A.; Galzerano, G.; Wehr, R.; Merlone, A.; Di Serafino, D.; Laporta, P.; Gianfrani, L.

    2008-01-01

    We report on a new optical implementation of primary gas thermometry based on laser absorption spectrometry in the near infrared. The method consists in retrieving the Doppler broadening from highly accurate observations of the line shape of the R(12) $\

  8. CO concentration and temperature sensor for combustion gases using quantum-cascade laser absorption near 4.7 μm

    KAUST Repository

    Ren, Wei; Farooq, Aamir; Davidson, David Frank; Hanson, Ronald Kenneth

    2012-01-01

    A sensor for sensitive in situ measurements of carbon monoxide and temperature in combustion gases has been developed using absorption transitions in the (v′ = 1 ← v″ = 0) and (v′ = 2 ← v″ = 1) fundamental bands of CO. Recent availability of mid-infrared quantum-cascade (QC) lasers provides convenient access to the CO fundamental band near 4.7 μm, having approximately 104 and 102 times stronger absorption line-strengths compared to the overtone bands near 1.55 μm and 2.3 μm used previously to sense CO in combustion gases. Spectroscopic parameters of the selected transitions were determined via laboratory measurements in a shock tube over the 1100-2000 K range and also at room temperature. A single-laser absorption sensor was developed for accurate CO measurements in shock-heated gases by scanning the line pair v″ = 0, R(12) and v″ = 1, R(21) at 2.5 kHz. To capture the rapidly varying CO time-histories in chemical reactions, two different QC lasers were then used to probe the line-center absorbance of transitions v″ = 0, P(20) and v″ = 1, R(21) with a bandwidth of 1 MHz using fixed-wavelength direct absorption. The sensor was applied in successful shock tube measurements of temperature and CO time-histories during the pyrolysis and oxidation of methyl formate, illustrating the capability of this sensor for chemical kinetic studies. © 2012 Springer-Verlag.

  9. CO concentration and temperature sensor for combustion gases using quantum-cascade laser absorption near 4.7 μm

    KAUST Repository

    Ren, Wei

    2012-05-25

    A sensor for sensitive in situ measurements of carbon monoxide and temperature in combustion gases has been developed using absorption transitions in the (v′ = 1 ← v″ = 0) and (v′ = 2 ← v″ = 1) fundamental bands of CO. Recent availability of mid-infrared quantum-cascade (QC) lasers provides convenient access to the CO fundamental band near 4.7 μm, having approximately 104 and 102 times stronger absorption line-strengths compared to the overtone bands near 1.55 μm and 2.3 μm used previously to sense CO in combustion gases. Spectroscopic parameters of the selected transitions were determined via laboratory measurements in a shock tube over the 1100-2000 K range and also at room temperature. A single-laser absorption sensor was developed for accurate CO measurements in shock-heated gases by scanning the line pair v″ = 0, R(12) and v″ = 1, R(21) at 2.5 kHz. To capture the rapidly varying CO time-histories in chemical reactions, two different QC lasers were then used to probe the line-center absorbance of transitions v″ = 0, P(20) and v″ = 1, R(21) with a bandwidth of 1 MHz using fixed-wavelength direct absorption. The sensor was applied in successful shock tube measurements of temperature and CO time-histories during the pyrolysis and oxidation of methyl formate, illustrating the capability of this sensor for chemical kinetic studies. © 2012 Springer-Verlag.

  10. Detection of 12 micron Mg I and OH lines in stellar spectra

    Science.gov (United States)

    Jennings, D. E.; Deming, D.; Wiedemann, G. R.; Keady, J. J.

    1986-01-01

    Infrared lines of Mg I and OH have been detected in stellar spectra near 12.3 microns. The Mg I 7i-6h transition was seen in Alpha Ori and Alpha Tau, and the R2e(23.5) and R1f(24.5) transitions of OH were seen in Alpha Ori. All lines appear in absorption, in contrast to the solar spectrum where the Mg I line shows a prominent emission core. The lack of emission in these low surface gravity stars is due to a greatly reduced volume recombination rate for the high-n states of Mg I, which is not fully compensated by the increased chromospheric scale height. The OH equivalent widths are sensitive to the temperature structure of the upper photosphere of Alpha Ori, and they indicate that the photosphere near tau 5000 of about 10 to the -5th is approximately 100 K hotter than is given by flux constant models. The OH measurements agree more closely with the 1981 semiemprical model of Basri, Linsky, and Eriksson (1981), which is based on Ca II and Mg II ultraviolet features.

  11. The absorption and transportation of ferric-salt in apple trees

    International Nuclear Information System (INIS)

    Xiong Zhixun; Chen Meihong

    1994-01-01

    59 Fe tracer technique was used to study the ferric-salt absorption, utilization and transportation in apple trees. The results indicated that absorption and utilization rate of ferric salt was 0.056%∼0.110% for roots and 30% for leaves, and that Fe is not easily to be transferred from one part to another. Fulvic acid iron had a better effect than ferrous sulfate. Ferric-salt absorption, utilization and transference were different among the cultivars. Intensive injections of ferrous salt into the apple trunks seemed to be more effective for correcting of chlorosis

  12. Quasar Absorption in the UV: Probing the Intergalactic Medium

    Science.gov (United States)

    Weinberg, David; Katz, Neal

    1998-01-01

    The purpose of this project is to model the low-redshift Lyman-alpha forest and exploration of the relation between Lyman-alpha absorbers and galaxies. This paper shows that the simulation models that are so successful at explaining properties of the high-redshift forest also account for the most important results of observational studies of the low-redshift forest, from HST (especially the Quasar Absorption Line Key Project) and ground-based follow-up.

  13. Absorption of Ultrashort Electromagnetic Pulses on Broadened Dipole Transitions

    International Nuclear Information System (INIS)

    Svita, S Yu; Astapenko, V A

    2014-01-01

    The study is devoted to the theoretical analysis of ultrashort electromagnetic pulses (USP) absorption on broadened dipole transitions. Calculations are made in the frame of perturbation theory with the use of the basic formula for energy absorbed during all time of the action of USP on dipole transition. Dependences of absorbed energy upon pulse duration and carrier frequency are obtained and analyzed for different types of spectral line shape and USP parameters

  14. Molecular absorption spectrometry in flames and furnaces: A review

    Energy Technology Data Exchange (ETDEWEB)

    Butcher, David J., E-mail: butcher@email.wcu.edu

    2013-12-04

    Graphical abstract: -- Highlights: •Theory and analytical considerations for molecular absorption spectrometry (MAS). •Critical review of low resolution MAS. •Critical review of the analytical performance of high-resolution continuum source (HR-CS) flame MAS. •Critical review of the analytical performance of HR-CS graphite furnace MAS. •Current status of HR-CS MAS and its future prospects for elemental analysis. -- Abstract: Molecular absorption spectrometry (MAS), originally developed in the 1970s, is a technique to determine non-metals in flames and graphite furnaces by monitoring the absorbance of diatomic molecules. Early studies employed low resolution instruments designed for line source atomic absorption, which provided a limited choice of analytical wavelengths, insufficient spectral resolution, and spectral interferences. However, the development of high-resolution continuum source atomic absorption spectrometry (HR-CS AAS) instrumentation has allowed the analysis of challenging samples for non-metals as well as some difficult elements to determine by AAS, such as aluminum and phosphorus. In this review, theory and analytical considerations for MAS are discussed. The principles and limitations of low resolution MAS are described, along with its applications. HR-CS AAS instrumentation is reviewed, emphasizing performance characteristics most relevant for MAS. Applications of flame and HR-CS GFMAS are reviewed, highlighting the most significant work to date. The paper concludes with an evaluation of the enhanced analytical capabilities provided by HR-CS MAS.

  15. Multimedia in physics education: two teaching videos on the absorption and emission spectrum of sodium

    International Nuclear Information System (INIS)

    Wagner, Andreas; Altherr, Stefan; Eckert, Bodo; Jodl, Hans Joerg

    2006-01-01

    In a series of letters we present teaching videos on topics where the learners of physics used to have problems. The first video presents an experimental set-up by which the absorption lines (D 1 , D 2 ) of sodium can be resolved simultaneous with the emission lines. The second video allows us to determine their wavelengths in comparison with calibrated spectral lines of mercury. This type of multimedia should not replace the real demonstration experiment, but is of good support for a long distant learner or for simply reading a textbook. (letters and comments)

  16. Infall toward High-Mass Star-forming Clumps and Cores: The [O I] 63 um Line

    Science.gov (United States)

    Jackson, James

    Although the 63 um line has often been used as a diagnostic of photodissociation regions, toward cold, dense infrared dark cloud clumps it is often seen in absorption. We aim to exploit this high optical depth in IRDCs to probe the infall velocities and mass accretion rates of high-mass star-forming clumps and cores. We will use "blue asymmetric" self-absorbed line profiles or redshifted absorption against the protostellar dust continuum to measure infall rates. We will target 8 IRDC clumps in NGC6334 and "Nessie" to probe how the infall rates may change with evolutionary stage.

  17. Effect of water vapour absorption on hydroxyl temperatures measured from Svalbard

    Directory of Open Access Journals (Sweden)

    J. M. Chadney

    2017-03-01

    Full Text Available We model absorption by atmospheric water vapour of hydroxyl airglow emission using the HIgh-resolution TRANsmission molecular absorption database (HITRAN2012. Transmission coefficients are provided as a function of water vapour column density for the strongest OH Meinel emission lines in the (8–3, (5–1, (9–4, (8–4, and (6–2 vibrational bands. These coefficients are used to determine precise OH(8–3 rotational temperatures from spectra measured by the High Throughput Imaging Echelle Spectrograph (HiTIES, installed at the Kjell Henriksen Observatory (KHO, Svalbard. The method described in this paper also allows us to estimate atmospheric water vapour content using the HiTIES instrument.

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

    International Nuclear Information System (INIS)

    Wu Hongbo; Tang Runsheng; Li Zhimin; Zhong Hao

    2009-01-01

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

  19. Influence of gamma rays colimation on Mosbauer lines

    International Nuclear Information System (INIS)

    Flores-Llamas, H.; Jimenez-Dominguez, Homero

    1989-01-01

    The effect of gamma rays collimation in Mossbauer absorption spectra was investigated when thin absorbers are used. A simple model is proposed to study shift and broadening of spectral lines. This model along with some approximations, makes the calculations easily done. The results are in good agreement with those in the literature. (author)

  20. Leaf absorption of 32P in the pumpkin

    International Nuclear Information System (INIS)

    Chamel, Andre; Roux-Aubert, M.T.

    1964-04-01

    The author presents a method to study the influence of various factors of the absorption of 32 P applied under the form of phosphates by a plant cultivated in conditions ensuring a normal development. Experiments provided indications on leaf absorption and 32 P transport by pumpkin leaves: phosphor 32 is absorbed and then quickly transported into the different organs of the plant (24 hours after treatment, it is present in aerial and underground parts), the quantity of absorbed phosphor increases with phosphor concentration in the applied solution, atmosphere humidity is an important factor for phosphor penetration into the leaves, plants absorb phosphor in darkness as well as in light, and the absorption of phosphor is not modified when applied with low glucose concentrations [fr

  1. Collision-induced absorption by D2 pairs in the first overtone band at 77, 201 and 298 K

    International Nuclear Information System (INIS)

    Abu-Kharma, M.; Gillard, P.G.; Reddy, S.P.

    2006-01-01

    Collision induced absorption (CIA) spectra of pure D 2 in the first overtone region from 5250 to 7250 cm -1 , recorded at 77, 201 and 298 K, have been analyzed. The observed spectra at 77, 201 and 298 K were modelled by a total of 92, 214 and 267 components respectively of double vibrational transitions at room temperature of the type X 2 (J) +X 0 (J) and X 1 (J) + X 1 (J), where X is O, Q or S transitions. Profile analyses of the spectra were carried out using the Birnbaum-Cohen line-shape function for the individual components of the band, and characteristic line shape parameters were determined from the analysis. The observed and calculated profiles agree well over the whole overtone band, and the agreement is better than 97% in the three cases studied. Binary and ternary absorption coefficients were determined from the integrated absorption of the band. (authors)

  2. An effective way to reduce water absorption to terahertz

    Science.gov (United States)

    Wu, Yaxiong; Su, Bo; He, Jingsuo; Zhang, Cong; Zhang, Hongfei; Zhang, Shengbo; Zhang, Cunlin

    2018-01-01

    Since many vibrations and rotational levels of biomolecules fall within the THz band, THz spectroscopy can be used to identify biological samples. In addition, most biomolecules need to maintain their biological activity in a liquid environment, but water as polar substance has strong absorption to the THz wave. Thus, it is difficult to detect the sample information in aqueous solution using THz wave. In order to prevent the information of biological samples were masked in the solution, many research methods were used to explore how to reduce the water absorption of terahertz. In this paper, we have developed a real-time chemical methodology through transmission Terahertz time-domain spectroscopy (THz-TDS) system. The material of Zeonor 1020r is used as substrate and cover plate, and PDMS as channel interlayer. The transmission of the empty microfluidic chip is more than 80% in the range of 0.2-2.6 THz by THz-TDS system. Then, experiments were carried out using chips, which were filled with different volumes of 1, 2- propanediol, and it has been proved that the microfluidic chip could reduce the water absorption of terahertz. Finally, in order to further explore the reduction of terahertz to water absorption, we inject different concentrations of electrolyte to the chip. The results show that with the addition of different electrolytes, terahertz transmission line has evident changes. It can be taken into account that the electrolyte has different effects about the hydrogen bonds in the aqueous solution. Some of them can promote water molecules clusters, while others destroy them. Based on the basis of microfluidic chip, the discovery of this phenomenon can provide a way that reduces water absorption of terahertz. This work has laid a solid foundation for the subsequent study in reducing water absorption of terahertz.

  3. Absorption studies

    International Nuclear Information System (INIS)

    Ganatra, R.D.

    1992-01-01

    Absorption studies were once quite popular but hardly anyone does them these days. It is easier to estimate the blood level of the nutrient directly by radioimmunoassay (RIA). However, the information obtained by estimating the blood levels of the nutrients is not the same that can be obtained from the absorption studies. Absorption studies are primarily done to find out whether some of the essential nutrients are absorbed from the gut or not and if they are absorbed, to determine how much is being absorbed. In the advanced countries, these tests were mostly done to detect pernicious anaemia where vitamin B 12 is not absorbed because of the lack of the intrinsic factor in the stomach. In the tropical countries, ''malabsorption syndrome'' is quire common. In this condition, several nutrients like fat, folic acid and vitamin B 12 are not absorbed. It is possible to study absorption of these nutrients by radioisotopic absorption studies

  4. WATER ABSORPTION IN GALACTIC TRANSLUCENT CLOUDS: CONDITIONS AND HISTORY OF THE GAS DERIVED FROM HERSCHEL /HIFI PRISMAS OBSERVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Flagey, N.; Goldsmith, P. F. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Lis, D. C.; Monje, R.; Phillips, T. G. [California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Gerin, M.; De Luca, M.; Godard, B. [LERMA, UMR 8112 du CNRS, Observatoire de Paris, Ecole Normale Superieure, UPMC and UCP (France); Neufeld, D. [Department of Physics and Astronomy, Johns Hopkins Univ. 3400 N. Charles St., Baltimore, MD 21218 (United States); Sonnentrucker, P. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Goicoechea, J. R., E-mail: nflagey@jpl.nasa.gov [Centro de Astrobiologia (CSIC-INTA), E-28850 Torrejon de Ardoz, Madrid (Spain)

    2013-01-01

    We present Herschel/HIFI observations of the three ground state transitions of H{sub 2}O (556, 1669, and 1113 GHz) and H{sub 2}{sup 18}O (547, 1655, and 1101 GHz)-as well as the first few excited transitions of H{sub 2}O (987, 752, and 1661 GHz)-toward six high-mass star-forming regions, obtained as part of the PRISMAS (PRobing InterStellar Molecules with Absorption line Studies) Guaranteed Time Key Program. Water vapor associated with the translucent clouds in Galactic arms is detected in absorption along every line of sight in all the ground state transitions. The continuum sources all exhibit broad water features in emission in the excited and ground state transitions. Strong absorption features associated with the source are also observed at all frequencies except 752 GHz. We model the background continuum and line emission to infer the optical depth of each translucent cloud along the lines of sight. We derive the column density of H{sub 2}O or H{sub 2}{sup 18}O for the lower energy level of each transition observed. The total column density of water in translucent clouds is usually about a few 10{sup 13} cm{sup -2}. We find that the abundance of water relative to hydrogen nuclei is 1 Multiplication-Sign 10{sup -8} in agreement with models for oxygen chemistry in which high cosmic ray ionization rates are assumed. Relative to molecular hydrogen, the abundance of water is remarkably constant through the Galactic plane with X(H{sub 2}O) =5 Multiplication-Sign 10{sup -8}, which makes water a good traced of H{sub 2} in translucent clouds. Observations of the excited transitions of H{sub 2}O enable us to constrain the abundance of water in excited levels to be at most 15%, implying that the excitation temperature, T {sub ex}, in the ground state transitions is below 10 K. Further analysis of the column densities derived from the two ortho ground state transitions indicates that T {sub ex} {approx_equal} 5 K and that the density n(H{sub 2}) in the translucent clouds

  5. Specific absorption rate analysis of broadband mobile antenna with negative index metamaterial

    Science.gov (United States)

    Alam, Touhidul; Faruque, Mohammad Rashed Iqbal; Islam, Mohammad Tariqul

    2016-03-01

    This paper presents a negative index metamaterial-inspired printed mobile wireless antenna that can support most mobile applications such as GSM, UMTS, Bluetooth and WLAN frequency bands. The antenna consists of a semi-circular patch, a 50Ω microstrip feed line and metamaterial ground plane. The antenna occupies a very small space of 37 × 47 × 0.508 mm3, making it suitable for mobile wireless application. The perceptible novelty shown in this proposed antenna is that reduction of specific absorption rate using the negative index metamaterial ground plane. The proposed antenna reduced 72.11 and 75.53 % of specific absorption rate at 1.8 and 2.4 GHz, respectively.

  6. Gamma Ray Absorption Technique For Scannig Process Column In Up-IV Pertamina Cilacap

    International Nuclear Information System (INIS)

    Santoso, Sigit Budi; Kushartono; Bisana; Mulyanto, Eko; Adi, Soecipto

    2000-01-01

    A demonstration using gamma ray absorption technique was carried out to diagnose malfunction such as tray missing, flooding, and weeping occurred in 2 3C-5 Extraction Vacuum Flash Strip Tower . The scan was conducted from the bottom until the top of the orientation of the director-source are (122 o -308 o ) dan (122 o - 270 o ). The results indicate that the tray number 1 and 3 were missing while weeping occurred in the space between tray 4,5,6,and 7. The results show that this technique can be used to diagnose malfunction occurred in the column on-line so it can help maintenance personnel in planning, the time scheduled and spare part for shutdown. Beside of that this technique can be developed to help column personnel's in adjusting the operation parameter to achieve optimum operation

  7. On-line preconcentration system using a microcolumn packed with Alizarin Red S-modified alumina for zinc determination by flame atomic absorption spectrometry

    Directory of Open Access Journals (Sweden)

    A.M. Haji Shabani

    2009-01-01

    Full Text Available A simple and sensitive on-line flow injection system for determination of zinc with FAAS has been described. The method is based on the separation and preconcentration of zinc on a microcolumn of immobilized Alizarin Red S on alumina. The adsorbed analyte is then eluted with 250 µL of nitric acid (1 mol L-1 and is transported to flame atomic absorption spectrometer for quantification. The effect of pH, sample and eluent flow rates and presence of various cations and anions on the retention of zinc was investigated. The sorption of zinc was quantitative in the pH range of 5.5-8.5. For a sample volume of 25 mL an enrichment factor of 144 and a detection limit (3S of 0.2 µg L-1 was obtained. The precision (RSD, n=7 was 3.0% at the 20 µg L-1 level. The developed system was successfully applied to the determination of zinc in water samples, hair, urine and saliva.

  8. Pulsed Airborne Lidar Measurements of C02 Column Absorption

    Science.gov (United States)

    Abshire, James B.; Riris, Haris; Allan, Graham R.; Weaver, Clark J.; Mao, Jianping; Sun, Xiaoli; Hasselbrack, William E.; Rodriquez, Michael; Browell, Edward V.

    2011-01-01

    We report on airborne lidar measurements of atmospheric CO2 column density for an approach being developed as a candidate for NASA's ASCENDS mission. It uses a pulsed dual-wavelength lidar measurement based on the integrated path differential absorption (IPDA) technique. We demonstrated the approach using the CO2 measurement from aircraft in July and August 2009 over four locations. The results show clear CO2 line shape and absorption signals, which follow the expected changes with aircraft altitude from 3 to 13 km. The 2009 measurements have been analyzed in detail and the results show approx.1 ppm random errors for 8-10 km altitudes and approx.30 sec averaging times. Airborne measurements were also made in 2010 with stronger signals and initial analysis shows approx. 0.3 ppm random errors for 80 sec averaging times for measurements at altitudes> 6 km.

  9. Modelling absorption and photoluminescence of TPD

    International Nuclear Information System (INIS)

    Vragovic, Igor; Calzado, Eva M.; Diaz Garcia, Maria A.; Himcinschi, C.; Gisslen, L.; Scholz, R.

    2008-01-01

    We analyse the optical spectra of N,N ' -diphenyl-N,N ' -bis(3-methyl-phenyl)-(1,1 ' -biphenyl)-4,4 ' -diamine (TPD) doped polystyrene films. The aim of the present paper is to give a microscopic interpretation of the significant Stokes shift between absorption and photoluminescence, which makes this material suitable for stimulated emission. The optimized geometric structures and energies of a neutral TPD monomer in ground and excited states are obtained by ab initio calculations using Hartree-Fock and density functional theory. The results indicate that the second distinct peak observed in absorption may arise either from a group of higher electronic transitions of the monomer or from the lowest optical transitions of a TPD dimer

  10. Absorption heat pumps

    International Nuclear Information System (INIS)

    Formigoni, C.

    1998-01-01

    A brief description of the difference between a compression and an absorption heat pump is made, and the reasons why absorption systems have spread lately are given. Studies and projects recently started in the field of absorption heat pumps, as well as criteria usually followed in project development are described. An outline (performance targets, basic components) of a project on a water/air absorption heat pump, running on natural gas or LPG, is given. The project was developed by the Robur Group as an evolution of a water absorption refrigerator operating with a water/ammonia solution, which has been on the market for a long time and recently innovated. Finally, a list of the main energy and cost advantages deriving from the use of absorption heat pumps is made [it

  11. Near-infrared free carrier absorption in heavily doped silicon

    International Nuclear Information System (INIS)

    Baker-Finch, Simeon C.; McIntosh, Keith R.; Yan, Di; Fong, Kean Chern; Kho, Teng C.

    2014-01-01

    Free carrier absorption in heavily doped silicon can have a significant impact on devices operating in the infrared. In the near infrared, the free carrier absorption process can compete with band to band absorption processes, thereby reducing the number of available photons to optoelectronic devices such as solar cells. In this work, we fabricate 18 heavily doped regions by phosphorus and boron diffusion into planar polished silicon wafers; the simple sample structure facilitates accurate and precise measurement of the free carrier absorptance. We measure and model reflectance and transmittance dispersion to arrive at a parameterisation for the free carrier absorption coefficient that applies in the wavelength range between 1000 and 1500 nm, and the range of dopant densities between ∼10 18 and 3 × 10 20  cm −3 . Our measurements indicate that previously published parameterisations underestimate the free carrier absorptance in phosphorus diffusions. On the other hand, published parameterisations are generally consistent with our measurements and model for boron diffusions. Our new model is the first to be assigned uncertainty and is well-suited to routine device analysis

  12. Absorption and Transport of Sea Cucumber Saponins from Apostichopus japonicus

    Directory of Open Access Journals (Sweden)

    Shuai Li

    2016-06-01

    Full Text Available The present study is focused on the intestinal absorption of sea cucumber saponins. We determined the pharmacokinetic characteristics and bioavailability of Echinoside A and Holotoxin A1; the findings indicated that the bioavailability of Holotoxin A1 was lower than Echinoside A. We inferred that the differences in chemical structure between compounds was a factor that explained their different characteristics of transport across the intestine. In order to confirm the absorption characteristics of Echinoside A and Holotoxin A1, we examined their transport across Caco-2 cell monolayer and effective permeability by single-pass intestinal perfusion. The results of Caco-2 cell model indicate that Echinoside A is transported by passive diffusion, and not influenced by the exocytosis of P-glycoprotein (P-gp, expressed in the apical side of Caco-2 monolayers as the classic inhibitor. The intestinal perfusion also demonstrated well the absorption of Echinoside A and poor absorption of Holotoxin A1, which matched up with the result of the Caco-2 cell model. The results demonstrated our conjecture and provides fundamental information on the relationship between the chemical structure of these sea cucumber saponins and their absorption characteristics, and we believe that our findings build a foundation for the further metabolism study of sea cucumber saponins and contribute to the further clinical research of saponins.

  13. The P K-near edge absorption spectra of phosphates

    Science.gov (United States)

    Franke, R.; Hormes, J.

    1995-12-01

    The X-ray absorption near edge structure (XANES) at the P K-edge in several orthophosphates with various cations, in condensed, and in substituted sodium phosphates have been measured using synchrotron radiation from the ELSA storage ring at the University of Bonn. The measured spectra demonstrate that chemical changes beyond the PO 4- tetrahedra are reflected by energy shifts of the pre-edge and continuum resonances, by the presence of characteristic shoulders and new peaks and by differences in the intensity of the white line. We discuss the energy differences between the white line positions and the corresponding P ls binding energies as a measure of half of the energy gap. The corresponding values correlate with the valence of the cations and the intensity of the white lines. The energy positions of the continuum resonances are discussed on the basis of an empirical bond-length correlation supporting a 1/ r2 - dependence.

  14. Analysis of a solar powered absorption system

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  15. Agnostic stacking of intergalactic doublet absorption: measuring the Ne VIII population

    Science.gov (United States)

    Frank, Stephan; Pieri, Matthew M.; Mathur, Smita; Danforth, Charles W.; Shull, J. Michael

    2018-05-01

    We present a blind search for doublet intergalactic metal absorption with a method dubbed `agnostic stacking'. Using a forward-modelling framework, we combine this with direct detections in the literature to measure the overall metal population. We apply this novel approach to the search for Ne VIII absorption in a set of 26 high-quality COS spectra. We probe to an unprecedented low limit of log N>12.3 at 0.47≤z ≤1.34 over a path-length Δz = 7.36. This method selects apparent absorption without requiring knowledge of its source. Stacking this mixed population dilutes doublet features in composite spectra in a deterministic manner, allowing us to measure the proportion corresponding to Ne VIII absorption. We stack potential Ne VIII absorption in two regimes: absorption too weak to be significant in direct line studies (12.3 13.7). We do not detect Ne VIII absorption in either regime. Combining our measurements with direct detections, we find that the Ne VIII population is reproduced with a power-law column density distribution function with slope β = -1.86 ^{+0.18 }_{ -0.26} and normalization log f_{13.7} = -13.99 ^{+0.20 }_{ -0.23}, leading to an incidence rate of strong Ne VIII absorbers dn/dz =1.38 ^{+0.97 }_{ -0.82}. We infer a cosmic mass density for Ne VIII gas with 12.3 value significantly lower that than predicted by recent simulations. We translate this density into an estimate of the baryon density Ωb ≈ 1.8 × 10-3, constituting 4 per cent of the total baryonic mass.

  16. Quasar Absorption Studies

    Science.gov (United States)

    Mushotzky, Richard (Technical Monitor); Elvis, Martin

    2004-01-01

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

  17. The Discovery of a High-Redshift Quasar without Emission Lines from Sloan Digital Sky Survey Commissioning Data.

    Science.gov (United States)

    Fan; Strauss; Gunn; Lupton; Carilli; Rupen; Schmidt; Moustakas; Davis; Annis; Bahcall; Brinkmann; Brunner; Csabai; Doi; Fukugita; Heckman; Hennessy; Hindsley; Ivezic; Knapp; Lamb; Munn; Pauls; Pier; Rockosi; Schneider; Szalay; Tucker; York

    1999-12-01

    We report observations of a luminous unresolved object at redshift z=4.62, with a featureless optical spectrum redward of the Lyalpha forest region, discovered from Sloan Digital Sky Survey commissioning data. The redshift is determined by the onset of the Lyalpha forest at lambda approximately 6800 Å and a Lyman limit system at lambda=5120 Å. A strong Lyalpha absorption system with weak metal absorption lines at z=4.58 is also identified in the spectrum. The object has a continuum absolute magnitude of -26.6 at 1450 Å in the rest frame (h0=0.5, q0=0.5) and therefore cannot be an ordinary galaxy. It shows no radio emission (the 3 sigma upper limit of its flux at 6 cm is 60 µJy), indicating a radio-to-optical flux ratio at least as small as that of the radio-weakest BL Lacertae objects known. It is also not linearly polarized to a 3 sigma upper limit of 4% in the observed I band. Therefore, it is either the most distant BL Lac object known to date, with very weak radio emission, or a new type of unbeamed quasar, whose broad emission line region is very weak or absent.

  18. Sound absorption study on acoustic panel from kapok fiber and egg tray

    Science.gov (United States)

    Kaamin, Masiri; Mahir, Nurul Syazwani Mohd; Kadir, Aslila Abd; Hamid, Nor Baizura; Mokhtar, Mardiha; Ngadiman, Norhayati

    2017-12-01

    Noise also known as a sound, especially one that is loud or unpleasant or that causes disruption. The level of noise can be reduced by using sound absorption panel. Currently, the market produces sound absorption panel, which use synthetic fibers that can cause harmful effects to the health of consumers. An awareness of using natural fibers from natural materials gets attention of some parties to use it as a sound absorbing material. Therefore, this study was conducted to investigate the potential of sound absorption panel using egg trays and kapok fibers. The test involved in this study was impedance tube test which aims to get sound absorption coefficient (SAC). The results showed that there was good sound absorption at low frequency from 0 Hz up to 900 Hz where the maximum absorption coefficient was 0.950 while the maximum absorption at high frequencies was 0.799. Through the noise reduction coefficient (NRC), the material produced NRC of 0.57 indicates that the materials are very absorbing. In addition, the reverberation room test was carried out to get the value of reverberation time (RT) in unit seconds. Overall this panel showed good results at low frequencies between 0 Hz up to 1500 Hz. In that range of frequency, the maximum reverberation time for the panel was 3.784 seconds compared to the maximum reverberation time for an empty room was 5.798 seconds. This study indicated that kapok fiber and egg tray as the material of absorption panel has a potential as environmental and cheap products in absorbing sound at low frequency.

  19. A quasi-continuous observation of the α-transition of Fe1+xS by Moessbauer line tracking

    International Nuclear Information System (INIS)

    Mendoza Zelis, P.; Pasquevich, G. A.; Veiga, A.; Fernandez van Raap, M. B.; Sanchez, F. H.

    2010-01-01

    Moessbauer absorption line tracking methodology, under a constant velocity strategy, is used for a quasi-continuous observation of the α-transition on slightly non stoichiometric Fe 1+x S alloy. To this end, two strategies were applied: an intelligent absorption line tracking with a control algorithm that uses the data measured in the previous region to establish the position of the next partial spectral range; and a predetermined line tracking in which temperature evolution of a partial spectral region of interest (ROI) is programmed. The latter uses results from the former, in order to achieve a quasi-continuous partial spectral observation. These experiments clearly demonstrate that line tracking allows a more efficient use of the radioactive source, as the effort is concentrated in a partial region of the spectra from which the desired information can be obtained.

  20. Optical absorption in recycled waste plastic polyethylene

    Science.gov (United States)

    Aji, M. P.; Rahmawati, I.; Priyanto, A.; Karunawan, J.; Wati, A. L.; Aryani, N. P.; Susanto; Wibowo, E.; Sulhadi

    2018-03-01

    We investigated the optical properties of UV spectrum absorption in recycled waste plastic from polyethylene polymer type. Waste plastic polyethylene showed an optical spectrum absorption after it’s recycling process. Spectrum absorption is determined using spectrophotometer UV-Nir Ocean Optics type USB 4000. Recycling method has been processed using heating treatment around the melting point temperature of the polyethylene polymer that are 200°C, 220°C, 240°C, 260°C, and 280°C. In addition, the recycling process was carried out with time variations as well, which are 1h, 1.5h, 2h, and 2.5h. The result of this experiment shows that recycled waste plastic polyethylene has a spectrum absorption in the ∼ 340-550 nm wavelength range. The absorbance spectrum obtained from UV light which is absorbed in the orbital n → π* and the orbital π → π*. This process indicates the existence of electron transition phenomena. This mechanism is affected by the temperature and the heating time where the intensity of absorption increases and widens with the increase of temperature and heating time. Furthermore this study resulted that the higher temperature affected the enhancement of the band gap energy of waste plastic polyethylene. These results show that recycled waste plastic polyethylene has a huge potential to be absorber materials for solar cell.

  1. Effect of an additional magnetic field on Hanle-type absorption resonances

    International Nuclear Information System (INIS)

    Singh Grewal, Raghwinder; Pattabiraman, M

    2014-01-01

    We computationally compare Hanle-type resonances for a F g =1→F e =0 transition of the 87 RbD 2 line for magnetic field scans parallel (longitudinal scan) and perpendicular (transverse scan) to the direction of propagation of the optical field in the presence of an additional transverse magnetic field (TMF). For a linearly polarized light, the coherent population trapping (CPT) resonances split at line centre and are identical for both longitudinal and transverse scans. When the probe beam ellipticity is varied, the effect of the TMF is found to be opposite for longitudinal and transverse scans. For a longitudinal scan, the splitting observed in the CPT resonance evolves into an enhanced absorption resonance with an increase in ellipticity. For a transverse scan, the splitting vanishes at higher ellipticities. This can be understood in terms of population redistribution in the ground state sublevels and near-neighbor ground state coherences created by the TMF. We also show that the enhanced absorption signal that splits the CPT resonance strongly depends on transit time, and the CPT resonance strength depends on the excited state dephasing rate. (paper)

  2. 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.

  3. Fluoride absorption: independence from plasma fluoride levels

    International Nuclear Information System (INIS)

    Whitford, G.M.; Williams, J.L.

    1986-01-01

    The concept that there are physiologic mechanisms to homeostatically regulate plasma fluoride concentrations has been supported by results in the literature suggesting an inverse relationship between plasma fluoride levels and the absorption of the ion from the gastrointestinal tract of the rat. The validity of the relationship was questioned because of possible problems in the experimental design. The present work used four different methods to evaluate the effect of plasma fluoride levels on the absorption of the ion in rats: (i) the percentage of the daily fluoride intake that was excreted in the urine; (ii) the concentration of fluoride in femur epiphyses; (iii) the net areas under the time-plasma fluoride concentration curves after intragastric fluoride doses; and (iv) the residual amounts or fluoride in the gastrointestinal tracts after the intragastric fluoride doses. None of these methods indicated that plasma fluoride levels influence the rate or the degree or fluoride absorption. It was concluded that, unless extremely high plasma fluoride levels are involved (pharmacologic or toxic doses), the absorption of the ion is independent of plasma levels. The results provide further evidence that plasma fluoride concentrations are not homeostatically regulated

  4. Identification of new solar OH lines in the 10--12 micron region

    International Nuclear Information System (INIS)

    Goldman, A.; Murcray, F.J.; Gillis, J.R.; Murcray, D.G.

    1981-01-01

    High-resolution (0.02 cm -1 ) infrared solar spectra obtained with a balloon-borne interferometer reveal new solar absorption features, which appear as regularly spaced quartets, in the 825--960 cm -1 region. The lines are interpreted as high N'' (25--33) pure rotation lines of solar OH. An effective amount of approx.8 x 10 15 molecules cm -2 of OH is estimated from the spectra

  5. Study the multi-photon absorption process in two types of molecules

    International Nuclear Information System (INIS)

    Al-azawi, H.R.

    1986-01-01

    The aim of the present work was to study the multi-photon absorption process in two types of molecules; spherical top such as SF 6 molecules and assymetric top such as CHOOH and C 2 H 4 molecules. This work also aimed to study the effect of buffer gas pressure (Ar), which is transparent to the infrared (IR) laser on the multiphoton absorption of both types of molecules. A pulsed (TEA) CO 2 laser was used as a source which generates multi-lines in the IR-region of the spectrum and an optoacoustic detector was used to detect the energy absorbed by the molecules. In this study, the relaxation process was found to be faster in the heavy molecules than that in the light ones. A limit in the Ar pressure was observed. Below this limit, the gas acted as an active buffer gas and above it, the multi-photon absorption process was quenched. This work also aimed to study the multi-photon absorption spectrum for the CHOOH molecules in the range (1067-1090 cm -1 ). This spectrum was found to be consistent with the linear absorption spectrum obtained for the same range. The density of the vibrational states as a function of the vibrational energy was studied for the molecules SF 6 , CHOOH and C 2 H 4 . The results were used to interpret (i) the difference in the energy absorbed by difference molecules at the same energy density and (ii) the non-linearity in the multi-photon absorption for CHOOH molecules. 1 tab.; 40 figs.; 70 refs

  6. Hyperammonemic encephalopathy due to suture line breakdown after bladder operation.

    Science.gov (United States)

    Boogerd, W; Zoetmulder, F A; Moffie, D

    1990-01-01

    A patient is described with a severe encephalopathy and hyperammonemia in absence of liver dysfunction, attributed to urine absorption into the systemic circulation due to suture line breakdown after bladder dome resection. At autopsy characteristic Alzheimer type II astrocytes were found in the basal ganglia.

  7. Collision-induced absorption by D{sub 2} pairs in the first overtone band at 77, 201 and 298 K

    Energy Technology Data Exchange (ETDEWEB)

    Abu-Kharma, M.; Gillard, P.G.; Reddy, S.P. [Memorial University of Newfoundland, Dept. of Physics and Physical Oceanography, Newfoundland (Canada)

    2006-01-15

    Collision induced absorption (CIA) spectra of pure D{sub 2} in the first overtone region from 5250 to 7250 cm{sup -1}, recorded at 77, 201 and 298 K, have been analyzed. The observed spectra at 77, 201 and 298 K were modelled by a total of 92, 214 and 267 components respectively of double vibrational transitions at room temperature of the type X{sub 2}(J) +X{sub 0}(J) and X{sub 1}(J) + X{sub 1}(J), where X is O, Q or S transitions. Profile analyses of the spectra were carried out using the Birnbaum-Cohen line-shape function for the individual components of the band, and characteristic line shape parameters were determined from the analysis. The observed and calculated profiles agree well over the whole overtone band, and the agreement is better than 97% in the three cases studied. Binary and ternary absorption coefficients were determined from the integrated absorption of the band. (authors)

  8. High-resolution H-band spectroscopy of Be stars with SDSS-III/apogee. I. New Be stars, line identifications, and line profiles

    International Nuclear Information System (INIS)

    Chojnowski, S. Drew; Majewski, Steven R.; Hall, Matthew; Beaton, Rachael; Burton, Adam; Damke, Guillermo; Wilson, John; Whelan, David G.; Wisniewski, John P.; Shetrone, Matthew; Eikenberry, Steve; Hasselquist, Sten; Holtzman, Jon A.; Brewington, Howard; Brinkmann, J.; Mészáros, Szabolcs; Nidever, David; Schneider, Donald P.; Zasowski, Gail; Bizyaev, Dmitry

    2015-01-01

    The Apache Point Observatory Galactic Evolution Experiment (APOGEE) has amassed the largest ever collection of multi-epoch, high-resolution (R∼22,500), H-band spectra for B-type emission line (Be) stars. These stars were targeted by APOGEE as telluric standard stars and subsequently identified via visual inspection as Be stars based on H i Brackett series emission or shell absorption in addition to otherwise smooth continua and occasionally non-hydrogen emission features. The 128/238 APOGEE Be stars for which emission had never previously been reported serve to increase the total number of known Be stars by ∼6%. Because the H band is relatively unexplored compared to other wavelength regimes, we focus here on identification of the H-band lines and analysis of the emission peak velocity separations (Δv p ) and emission peak intensity ratios (V/R) of the usually double-peaked H i and non-hydrogen emission lines. H i Br11 emission is found to preferentially form in the circumstellar disks at an average distance of ∼2.2 stellar radii. Increasing Δv p toward the weaker Br12–Br20 lines suggests these lines are formed interior to Br11. By contrast, the observed IR Fe ii emission lines present evidence of having significantly larger formation radii; distinctive phase lags between IR Fe ii and H i Brackett emission lines further supports that these species arise from different radii in Be disks. Several emission lines have been identified for the first time including C i 16895, a prominent feature in the spectra for almost a fifth of the sample and, as inferred from relatively large Δv p compared to the Br11–Br20, a tracer of the inner regions of Be disks. Emission lines at 15760 Å and 16781 Å remain unidentified, but usually appear along with and always have similar line profile morphology to Fe ii 16878. Unlike the typical metallic lines observed for Be stars in the optical, the H-band metallic lines, such as Fe ii 16878, never exhibit any evidence of

  9. Absorptive coding metasurface for further radar cross section reduction

    Science.gov (United States)

    Sui, Sai; Ma, Hua; Wang, Jiafu; Pang, Yongqiang; Feng, Mingde; Xu, Zhuo; Qu, Shaobo

    2018-02-01

    Lossless coding metasurfaces and metamaterial absorbers have been widely used for radar cross section (RCS) reduction and stealth applications, which merely depend on redirecting electromagnetic wave energy into various oblique angles or absorbing electromagnetic energy, respectively. Here, an absorptive coding metasurface capable of both the flexible manipulation of backward scattering and further wideband bistatic RCS reduction is proposed. The original idea is carried out by utilizing absorptive elements, such as metamaterial absorbers, to establish a coding metasurface. We establish an analytical connection between an arbitrary absorptive coding metasurface arrangement of both the amplitude and phase and its far-field pattern. Then, as an example, an absorptive coding metasurface is demonstrated as a nonperiodic metamaterial absorber, which indicates an expected better performance of RCS reduction than the traditional lossless coding metasurface and periodic metamaterial-absorber. Both theoretical analysis and full-wave simulation results show good accordance with the experiment.

  10. Impurity profiling of liothyronine sodium by means of reversed phase HPLC, high resolution mass spectrometry, on-line H/D exchange and UV/Vis absorption.

    Science.gov (United States)

    Ruggenthaler, M; Grass, J; Schuh, W; Huber, C G; Reischl, R J

    2017-09-05

    For the first time, a comprehensive investigation of the impurity profile of the synthetic thyroid API (active pharmaceutical ingredient) liothyronine sodium (LT 3 Na) was performed by using reversed phase HPLC and advanced structural elucidation techniques including high resolution tandem mass spectrometry (HRMS/MS) and on-line hydrogen-deuterium (H/D) exchange. Overall, 39 compounds were characterized and 25 of these related substances were previously unknown to literature. The impurity classification system recently developed for the closely related API levothyroxine sodium (LT 4 Na) could be applied to the newly characterized liothyronine sodium impurities resulting in a wholistic thyroid API impurity classification system. Furthermore, the mass-spectrometric CID-fragmentation of specific related substances was discussed and rationalized by detailed fragmentation pathways. Moreover, the UV/Vis absorption characteristics of the API and selected impurities were investigated to corroborate chemical structure assignments derived from MS data. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. An efficient method for computing the absorption of solar radiation by water vapor

    Science.gov (United States)

    Chou, M.-D.; Arking, A.

    1981-01-01

    Chou and Arking (1980) have developed a fast but accurate method for computing the IR cooling rate due to water vapor. Using a similar approach, the considered investigation develops a method for computing the heating rates due to the absorption of solar radiation by water vapor in the wavelength range from 4 to 8.3 micrometers. The validity of the method is verified by comparison with line-by-line calculations. An outline is provided of an efficient method for transmittance and flux computations based upon actual line parameters. High speed is achieved by employing a one-parameter scaling approximation to convert an inhomogeneous path into an equivalent homogeneous path at suitably chosen reference conditions.

  12. HIFI Spectroscopy of H2O Submillimeter Lines in Nuclei of Actively Star-forming Galaxies

    Science.gov (United States)

    Liu, L.; Weiß, A.; Perez-Beaupuits, J. P.; Güsten, R.; Liu, D.; Gao, Y.; Menten, K. M.; van der Werf, P.; Israel, F. P.; Harris, A.; Martin-Pintado, J.; Requena-Torres, M. A.; Stutzki, J.

    2017-09-01

    We present a systematic survey of multiple velocity-resolved H2O spectra using Herschel/Heterodyne Instrument for the Far Infrared (HIFI) toward nine nearby actively star-forming galaxies. The ground-state and low-excitation lines (E up ≤ 130 K) show profiles with emission and absorption blended together, while absorption-free medium-excitation lines (130 K ≤ E up ≤ 350 K) typically display line shapes similar to CO. We analyze the HIFI observation together with archival SPIRE/PACS H2O data using a state-of-the-art 3D radiative transfer code that includes the interaction between continuum and line emission. The water excitation models are combined with information on the dust and CO spectral line energy distribution to determine the physical structure of the interstellar medium (ISM). We identify two ISM components that are common to all galaxies: a warm ({T}{dust}˜ 40{--}70 K), dense (n({{H}})˜ {10}5{--}{10}6 {{cm}}-3) phase that dominates the emission of medium-excitation H2O lines. This gas phase also dominates the far-IR emission and the CO intensities for {J}{up}> 8. In addition, a cold ({T}{dust}˜ 20{--}30 K), dense (n({{H}})˜ {10}4{--}{10}5 {{cm}}-3), more extended phase is present. It outputs the emission in the low-excitation H2O lines and typically also produces the prominent line absorption features. For the two ULIRGs in our sample (Arp 220 and Mrk 231) an even hotter and more compact (R s ≤ 100 pc) region is present, which is possibly linked to AGN activity. We find that collisions dominate the water excitation in the cold gas and for lines with {E}{up}≤slant 300 K and {E}{up}≤slant 800 K in the warm and hot component, respectively. Higher-energy levels are mainly excited by IR pumping.

  13. Spectroscopy of the 4.6 - 4.7 micron interstellar absorption features

    International Nuclear Information System (INIS)

    Geballe, T.R.

    1984-01-01

    Perhaps the most successful application of spectroscopy to the study of interstellar solid state infrared absorption features has been in the case of the previously unidentified feature near 4.6 μm first seen in absorption toward the protostar W33A. Whereas the original spectrum of this object, obtained at a resolving power of 70, revealed only a single deep absorption feature, a later spectrum, using a single channel grating spectrometer at ten times the resolving power, indicates that it is made up of three separate components. The central narrow absorption feature at 2140 cm -1 (4.67 μm) coincides in wavelength precisely with that of solid CO. It and its unresolved shoulder at just lower frequency have now been seen quite commonly in absorption toward other protostars. The broad absorption seen in W33A at 2165 cm -1 (4.62 μm) is apparently much less common. (author)

  14. An empirical line-by-line model for the infrared solar transmittance spectrum from 700 to 5000cm{sup -1}

    Energy Technology Data Exchange (ETDEWEB)

    Hase, F. [Institut fuer Meteorologie und Klimaforschung, Forschungszentrum Karlsruhe, Postfach 3640, D-76021 Karlsruhe (Germany)]. E-mail: frank.hase@imk.fzk.de; Demoulin, P. [Institut d' Astrophysique et de Geophysique, allee du VI aout, 17, batiment B5a, B-4000, Liege (Belgium); Sauval, A.J. [Observatoire Royal de Belgique, avenue circulaire, 3, B-1180, Bruxelles (Belgium); Toon, G.C. [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Bernath, P.F. [Department of Chemistry, University of Waterloo, Waterloo, Ont., Canada N2L3G1 (Canada); Goldman, A. [Department of Physics, University of Denver, Denver, CO 80208 (United States); Hannigan, J.W. [Atmospheric Chemistry Division, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80303 (United States); Rinsland, C.P. [NASA Langley Research Center, Hampton, VA 23681-2199 (United States)

    2006-12-15

    An empirical line-by-line model for the infrared solar transmittance spectrum is presented. The model can be incorporated into radiative transfer codes to allow fast calculation of all relevant emission and absorption features in the solar spectrum in the mid-infrared region from 700 to 5000cm{sup -1}. The transmittance is modelled as a function of the diameter of the field-of-view centered on the solar disk: the line broadening due to solar rotation as well as center-to-limb variations in strength and width are taken into account for stronger lines. Applications of the model presented here are in the fields of terrestrial remote sensing in the mid-infrared spectral region when the sun is used as radiation source or scattered solar radiation contributes to the measured signal and in the fields of atmospheric radiative transfer algorithms which compute the propagation of infrared solar radiation in the terrestrial atmosphere.

  15. Topical absorption and toxicity studies of jet fuel hydrocarbons in skin

    Science.gov (United States)

    Muhammad, Faqir

    Kerosene-based fuels have been used for many decades. Over 2 million military and civilian personnel each year are occupationally exposed to various jet fuel mixtures. Dermatitis is one of the major health concerns associated with these exposures. In the past, separate absorption and toxicity studies have been conducted to find the etiology of such skin disorders. There was a need for integrated absorption and toxicity studies to define the causative constituents of jet fuel responsible for skin irritation. The focus of this thesis was to study the percutaneous absorption and to identify the hydrocarbons (HC) causing irritation in jet fuels so that preventive measures could be taken in the future. The initial study was conducted to understand the possible mechanism for additive interactions on hydrocarbon absorption/disposition in silastic, porcine skin and isolated perfused porcine skin flap (IPPSF) models. The influence of JP-8 (100) additives (MDA, BHT, 8Q405) on the dermal kinetics of 14C-naphthalene and 14C/3H-dodecane as markers of HC absorption was evaluated. This study indicated that individual and combination of additives influenced marker disposition in different membranes. MDA was a significant suppressor while BHT was a significant enhancer of naphthalene absorption in IPPSF. The 8Q405 significantly reduced naphthalene content in dosed silastic and skin indicating a direct interaction between additive and marker HC. Similarly, the individual MDA and BHT significantly retained naphthalene in the stratum corneum of porcine skin, but the combination of both of these additives statistically decreased the marker retention in the stratum corneum suggesting a potential biological interaction. This study concluded that all components of a chemical mixture should be assessed since the effects of single components administered alone or as pairs may be confounded when all are present in the complete mixture. However, this study indicated that the marker HC

  16. Origin of Magnetism in Hydrothermally Aged 2-Line Ferrihydrite Suspensions.

    Science.gov (United States)

    Cao, Liang; Jiang, Zhao-Xia; Du, Yong-Hua; Yin, Xin-Mao; Xi, Shi-Bo; Wen, Wen; Roberts, Andrew P; Wee, Andrew T S; Xiong, Yi-Min; Liu, Qing-Song; Gao, Xing-Yu

    2017-03-07

    As an iron oxyhydroxide, nanosized ferrihydrite (Fh) is important in Earth science, biology, and industrial applications. However, its basic structure and origin of its magnetism have long been debated. We integrate synchrotron-based techniques to explore the chemical structures of 2-line ferrihydrite and to determine the origin of its magnetism during hydrothermal aging in air. Our results demonstrate that both the magnetism and X-ray magnetic circular dichroism (XMCD) signal of 2-line ferrihydrite are enhanced with aging time, and that XMCD spectral patterns resemble that of maghemite (γ-Fe 2 O 3 ) rather than magnetite (Fe 3 O 4 ). Fe L-edge and K-edge X-ray absorption spectroscopy (XAS) further indicate formation of both maghemite and hematite (α-Fe 2 O 3 ) with increasing concentrations with longer hydrothermal aging time. Thus, magnetic enhancement with longer hydrothermal aging time is attributed to increasing maghemite concentration instead of a magnetically ordered ferrihydrite as previously reported. Moreover, L-edge and K-edge XAS spectra with different probing depths yield different ratios of these Fe oxides, which suggest the formation of a core (ferrihydrite-rich)-shell (with a mixture of both allotropes; α-Fe 2 O 3 and γ-Fe 2 O 3 ) structure during hydrothermal aging. Our results provide insights into the chemical evolution of 2-line ferrihydrite that reveal unambiguously the origin of its magnetism.

  17. Polarization control of intermediate state absorption in resonance-mediated multi-photon absorption process

    International Nuclear Information System (INIS)

    Xu, Shuwu; Yao, Yunhua; Jia, Tianqing; Ding, Jingxin; Zhang, Shian; Sun, Zhenrong; Huang, Yunxia

    2015-01-01

    We theoretically and experimentally demonstrate the control of the intermediate state absorption in an (n + m) resonance-mediated multi-photon absorption process by the polarization-modulated femtosecond laser pulse. An analytical solution of the intermediate state absorption in a resonance-mediated multi-photon absorption process is obtained based on the time-dependent perturbation theory. Our theoretical results show that the control efficiency of the intermediate state absorption by the polarization modulation is independent of the laser intensity when the transition from the intermediate state to the final state is coupled by the single-photon absorption, but will be affected by the laser intensity when this transition is coupled by the non-resonant multi-photon absorption. These theoretical results are experimentally confirmed via a two-photon fluorescence control in (2 + 1) resonance-mediated three-photon absorption of Coumarin 480 dye and a single-photon fluorescence control in (1 + 2) resonance-mediated three-photon absorption of IR 125 dye. (paper)

  18. [Determination of sulfur in plant using a high-resolution continuum source atomic absorption spectrometer].

    Science.gov (United States)

    Wang, Yu; Li, Jia-xi

    2009-05-01

    A method for the analysis of sulfur (S) in plant by molecular absorption of carbon monosulfide (CS) using a high-resolution continuum source atomic absorption spectrometer (CS AAS) with a fuel-rich air/acetylene flame has been devised. The strong CS absorption band was found around 258 nm. The half-widths of some absorption bands were of the order of picometers, the same as the common atomic absorption lines. The experimental procedure in this study provided optimized instrumental conditions (the ratio of acetylene to air, the burner height) and parameters, and researched the spectral interferences and chemical interferences. The influence of the organic solvents on the CS absorption signals and the different digestion procedures for the determination of sulfur were also investigated. The limit of detection achieved for sulfur was 14 mg x L(-1), using the CS wavelength of 257. 961 nm and a measurement time of 3 s. The accuracy and precision were verified by analysis of two plant standard reference materials. The major applications of this method have been used for the determination of sulfur in plant materials, such as leaves. Compared to the others, this method for the analysis of sulfur is rapid, easy and simple for sulfur determination in plant.

  19. Microwave absorption properties of polypyrrole-SrFe12O19-TiO2-epoxy resin nanocomposites: Optimization using response surface methodology

    Science.gov (United States)

    Seyed Dorraji, M. S.; Rasoulifard, M. H.; Amani-Ghadim, A. R.; Khodabandeloo, M. H.; Felekari, M.; Khoshrou, M. R.; hajimiri, I.

    2016-10-01

    At a few works are discussed about formation of heterogeneous composites with different distribution of particle shape and size that are used for electromagnetic absorption purposes. In this study a novel heterogeneous nanocpmposites is investigated. The nanocomposite has been successfully prepared based on epoxy resin including various nano-metal oxides (TiO2, SrFe12O19) and polypyrrole (PPy) by sol-gel and the solution chemistry method, respectively. The performance of prepared nanocomposite in absorption of microwave in X-band range was investigated and transmission line method by X-band waveguide straight was used to measure EM parameters of nanocomposites. The Response surface methodology (RSM) with central composite design (CCD) was utilized to study the effects of the wt.% TiO2 in SrFe12O19, wt.% Tio2-SrFe12O19 in PPy and wt.% TiO2-SrFe12O19-PPy in epoxy resin, on the microwave absorption properties with the absorber thickness of only 2 mm. The proposed quadratic model was in accordance with the experimental results with correlation coefficient of 96.5%. The optimum condition for maximum microwave absorption efficiency were wt.% TiO2 in SrFe12O19 of 70, wt.% TiO2-SrFe12O19 in PPy of 10 and wt.% TiO2-SrFe12O19-PPy in epoxy of 25. The sample prepared in optimal conditions indicated reflection loss of -15 dB corresponding to 97% absorption, at the range of 9.2-10.8 GHz.

  20. Modelling absorption and photoluminescence of TPD

    Energy Technology Data Exchange (ETDEWEB)

    Vragovic, Igor [Dpto. de Fisica Aplicada and Inst. Universitario de Materiales de Alicante, Universidad de Alicante, E-03080 Alicante (Spain)], E-mail: igor.vragovic@ua.es; Calzado, Eva M.; Diaz Garcia, Maria A.; Himcinschi, C. [Max-Planck-Institut fuer Mikrostrukturphysik, D-06120 Halle (Germany); Gisslen, L.; Scholz, R. [Walter Schottky Institut, Technische Universitaet Muenchen, D-85748 Garching (Germany)

    2008-05-15

    We analyse the optical spectra of N,N{sup '}-diphenyl-N,N{sup '}-bis(3-methyl-phenyl)-(1,1{sup '}-biphenyl)-4,4{sup '}-diamine (TPD) doped polystyrene films. The aim of the present paper is to give a microscopic interpretation of the significant Stokes shift between absorption and photoluminescence, which makes this material suitable for stimulated emission. The optimized geometric structures and energies of a neutral TPD monomer in ground and excited states are obtained by ab initio calculations using Hartree-Fock and density functional theory. The results indicate that the second distinct peak observed in absorption may arise either from a group of higher electronic transitions of the monomer or from the lowest optical transitions of a TPD dimer.

  1. Identification of the lines in the L emission spectrum of cerium and samarium

    International Nuclear Information System (INIS)

    Shrivastava, B.D.; Singh, D.

    1992-01-01

    The occurrence of a line at 2.1556 A in the L emission spectrum of cerium and two lines at 1.6679 and 1.8379 A in the L emission spectrum of samarium, reported many years ago, has remained a puzzle. These have now been identified as EXAFS minima occurring at the L absorption edges of the respective elements. (author)

  2. Prospects for higher spatial resolution quantitative X-ray analysis using transition element L-lines

    Science.gov (United States)

    Statham, P.; Holland, J.

    2014-03-01

    Lowering electron beam kV reduces electron scattering and improves spatial resolution of X-ray analysis. However, a previous round robin analysis of steels at 5 - 6 kV using Lα-lines for the first row transition elements gave poor accuracies. Our experiments on SS63 steel using Lα-lines show similar biases in Cr and Ni that cannot be corrected with changes to self-absorption coefficients or carbon coating. The inaccuracy may be caused by different probabilities for emission and anomalous self-absorption for the La-line between specimen and pure element standard. Analysis using Ll(L3-M1)-lines gives more accurate results for SS63 plausibly because the M1-shell is not so vulnerable to the atomic environment as the unfilled M4,5-shell. However, Ll-intensities are very weak and WDS analysis may be impractical for some applications. EDS with large area SDD offers orders of magnitude faster analysis and achieves similar results to WDS analysis with Lα-lines but poorer energy resolution precludes the use of Ll-lines in most situations. EDS analysis of K-lines at low overvoltage is an alternative strategy for improving spatial resolution that could give higher accuracy. The trade-off between low kV versus low overvoltage is explored in terms of sensitivity for element detection for different elements.

  3. Role of noise in the diode-laser spectroscopy of the spectral line profile

    International Nuclear Information System (INIS)

    Nadezhdinskii, Aleksandr I; Plotnichenko, V V; Ponurovskii, Ya Ya; Spiridonov, Maksim V

    2000-01-01

    Questions concerning precise measurements of the spectral-line-profile parameters by diode-laser spectroscopic methods were examined. The instrumental function of a distributed-feedback diode laser (λ =1.53 μm), consisting of the additive contributions of the noise due to spontaneous emission, frequency fluctuations, and intensity fluctuations, was investigated. An analytical formula was obtained for the spectrum of the diode-laser field formed by frequency fluctuations. The spectral density g 0 of the frequency fluctuations, determining the width of the central part of the emission line profile of a diode laser, was found by two independent methods (by fitting to a Doppler-broadened absorption line profile and by finding the intensity of the residual radiation and the saturated-absorption line width). The parameters Ω and Γ of the spectral density of the frequency fluctuations, coupled to the relaxation oscillations and determining the wing of the diode-laser emission line profile, were determined experimentally. By taking into account the instrumental function of the diode laser, involving successive convolution with the recorded emission spectra, it was possible to reproduce correctly the spectral line profile and to solve accurately the problem of the 'optical zero'. The role of the correlation between the intensity noise and the diode-laser frequency was considered. (laser applications and other topics in quantum electronics)

  4. Interband optical absorption in the Wannier-Stark ladder under the electron-LO-phonon resonance condition

    International Nuclear Information System (INIS)

    Govorov, A.O.

    1993-08-01

    Interband optical absorption in the Wannier-Stark ladder in the presence of the electron-LO-phonon resonance is investigated theoretically. The electron-LO-phonon resonance occurs when the energy spacing between adjacent Stark-ladder levels coincides with the LO-phonon energy. We propose a model describing the polaron effect in a superlattice. Calculations show that the absorption line shape is strongly modified due to the polaron effect under the electron-LO-phonon resonance condition. We consider optical phenomena in a normal magnetic field that leads to enhancement of polaron effects. (author). 17 refs, 5 figs

  5. SEARCHING FOR NAPHTHALENE CATION ABSORPTION IN THE INTERSTELLAR MEDIUM

    International Nuclear Information System (INIS)

    Searles, Justin M.; Destree, Joshua D.; Snow, Theodore P.; Salama, Farid; York, Donald G.; Dahlstrom, Julie

    2011-01-01

    Interstellar naphthalene cations (C 10 H + 8 ) have been proposed by a study to be the carriers of a small number of diffuse interstellar bands (DIBs). Using an archive of high signal-to-noise spectra obtained at the Apache Point Observatory, we used two methods to test the hypothesis. Both methods failed to detect significant absorption at lab wavelengths of interstellar spectra with laboratory spectra. We thereby conclude that C 10 H + 8 is not a DIB carrier in typical reddened sight lines.

  6. Free radicals in irradiated unstabilized polypropylene, as seen by diffuse reflection absorption-spectrophotometry

    International Nuclear Information System (INIS)

    Zagorski, Z.P.; Rafalski, A.

    1998-01-01

    The introduction of UV-Vis absorption spectrophotometry to the study of radiation chemistry of polymers has opened the possibility to investigate even very opaque samples. The virgin powder polypropylene, as obtained from the industrial production line, shows after irradiation unstable products of radiolysis. Until now they were investigated mainly by EPR method. Optical absorption spectra (by diffuse reflection spectrophotometry) contribute to better identification and study of changes in time, temperature and diffusion of reactive gases. Studying the formation of stable compounds, which do not produce EPR signal, we are able to examine these species on the basis of their electronic spectra. The most important results concern the peroxides in irradiated polypropylene

  7. Romania's road to Euro zone. From structural balance to structural balance corrected for absorption

    Directory of Open Access Journals (Sweden)

    Aura-Gabriela SOCOL

    2013-02-01

    Full Text Available The sovereign-debt crisis in the European Union has determined the necessity to reform the signal indicators for the analysis of the public finances' sustainability. In this context, many of the developing/emerging countries consider that the informational value provided by the structural budget balance indicator is insufficient, especially during the periods characterized by absorption. The present study suggests the transition from classical structural budget balance (CAB in the structural balance corrected for absorption (CAAB and supports the use of an improved indicator of the structural budget balance with a superior informational relevance for the macro-economic policies decision makers. Based on the economic literature we will demonstrate that the structural budget balance indicator should be improved, in order to also take into consideration the deviation of the current account balance from its sustainable level, particularly in the stage of the economic cycle characterized by high absorption.

  8. In Silico Modeling of Gastrointestinal Drug Absorption: Predictive Performance of Three Physiologically Based Absorption Models.

    Science.gov (United States)

    Sjögren, Erik; Thörn, Helena; Tannergren, Christer

    2016-06-06

    particle size. In conclusion, it was shown that all three software packages are useful to guide formulation development. However, as a consequence of the high fraction of inaccurate predictions (prediction error >2-fold) and the clear trend toward decreased accuracy with decreased predicted fabs observed with Simcyp, the results indicate that GI-Sim and GastroPlus perform better than Simcyp in predicting the intestinal absorption of the incompletely absorbed drugs when a higher degree of accuracy is needed. In addition, this study suggests that modeling and simulation research groups should perform systematic model evaluations using their own input data to maximize confidence in model performance and output.

  9. On-line detection of small radioactive ions by capillary electrophoresis

    International Nuclear Information System (INIS)

    Klunder, G.L.; Andrews, J.E. Jr.; Russo, R.E.

    1994-01-01

    Worldwide environmental interests have placed a great demand on developing techniques for rapid characterization of contaminated soil and groundwater. Detection of radioactive contaminants is necessary for monitoring effluents from nuclear processes or to assure proper long term storage of radioactive waste. The authors have been investigating the chemistry required to separate representative radioactive small cations and anions by capillary electrophoresis. In order to evaluate the separation chemistry, detection of stable isotopes of the representative ions was achieved by indirect absorption for cations and direct absorption for anions. Several buffer systems which have been considered in the optimization of the separations will be discussed. The authors have designed and tested two on-line radioactivity detectors for capillary electrophoresis. An on-line solid state CdTe detector was constructed for this study and a scintillation detector has been designed using a high gain photodiode light sensor. Different scintillation materials have been tested. Comparison of the detectors, design considerations, efficiency and limits of detection will be presented

  10. Ultraviolet observations of cool stars. III. Chromospheric and coronal lines in α Tauri, β Geminorum, and α Bootis

    International Nuclear Information System (INIS)

    McClintock, W.; Linsky, J.L.; Henry, R.C.; Moos, H.W.; Gerola, H.

    1975-01-01

    The ultraviolet spectrometer of the Princeton Experiment Package aboard the Copernicus satellite has been used to obtain high-resolution measurements of Lα, the Mg ii lambda2800 doublet, and upper limits on the Si iii lambda1206 line in the K giants α Tau and β Gem. The intensities and line shapes are compared with earlier observations of α Boo. The Lα and Mg ii profiles for α Tau resemble those for α Boo, in that they are highly asymmetrical, while β Gem shows much more symmetrical profiles. The asymmetries for all lines except for those of α Boo and Mg ii lines of α Tau could be due to interstellar absorption. In the case of β Gem only, the O v intercombination line at 1218 A is observed, suggesting a well-developed corona substantially cooler than that of the Sun. The Lα profiles of α Tau and β Gem are consistent with the low interstellar hydrogen abundance in the solar neighborhood previously obtained from a similar observation of the α Boo Lα profile. The strength of the Mg ii lambda2796 line can be used to measure transition region and coronal pressures, and indicates a decrease in both with later spectral type and/or increasing luminosity

  11. Repetitively Mode-Locked Cavity-Enhanced Absorption Spectroscopy (RML-CEAS for Near-Infrared Gas Sensing

    Directory of Open Access Journals (Sweden)

    Qixin He

    2017-12-01

    Full Text Available A Pound-Drever-Hall (PDH-based mode-locked cavity-enhanced sensor system was developed using a distributed feedback diode laser centered at 1.53 µm as the laser source. Laser temperature scanning, bias control of the piezoelectric ceramic transducer (PZT and proportional-integral-derivative (PID feedback control of diode laser current were used to repetitively lock the laser modes to the cavity modes. A gas absorption spectrum was obtained by using a series of absorption data from the discrete mode-locked points. The 15 cm-long Fabry-Perot cavity was sealed using an enclosure with an inlet and outlet for gas pumping and a PZT for cavity length tuning. The performance of the sensor system was evaluated by conducting water vapor measurements. A linear relationship was observed between the measured absorption signal amplitude and the H2O concentration. A minimum detectable absorption coefficient of 1.5 × 10–8 cm–1 was achieved with an averaging time of 700 s. This technique can also be used for the detection of other trace gas species by targeting the corresponding gas absorption line.

  12. A quasi-continuous observation of the {alpha}-transition of Fe{sub 1+x}S by Moessbauer line tracking

    Energy Technology Data Exchange (ETDEWEB)

    Mendoza Zelis, P., E-mail: pmendoza@fisica.unlp.edu.ar; Pasquevich, G. A.; Veiga, A.; Fernandez van Raap, M. B.; Sanchez, F. H. [Universidad Nacional de La Plata, CONICET, Depto. de Fisica, Fac. Ciencias Exactas, Instituto de Fisica La Plata (Argentina)

    2010-01-15

    Moessbauer absorption line tracking methodology, under a constant velocity strategy, is used for a quasi-continuous observation of the {alpha}-transition on slightly non stoichiometric Fe{sub 1+x}S alloy. To this end, two strategies were applied: an intelligent absorption line tracking with a control algorithm that uses the data measured in the previous region to establish the position of the next partial spectral range; and a predetermined line tracking in which temperature evolution of a partial spectral region of interest (ROI) is programmed. The latter uses results from the former, in order to achieve a quasi-continuous partial spectral observation. These experiments clearly demonstrate that line tracking allows a more efficient use of the radioactive source, as the effort is concentrated in a partial region of the spectra from which the desired information can be obtained.

  13. No “Maunder Minimum” Candidates in M67: Mitigating Interstellar Contamination of Chromospheric Emission Lines

    Energy Technology Data Exchange (ETDEWEB)

    Curtis, Jason Lee, E-mail: jasoncurtis.astro@gmail.com [Department of Astronomy, Columbia University, 550 West 120th Street, New York, NY 10027 (United States)

    2017-06-01

    The solar analogs of M67 let us glimpse the probable behavior of the Sun on timescales surpassing the duration of human civilization. M67 can serve as a solar proxy because its stars share a similar age and composition with the Sun. Previous surveys of M67 observed that 15% of its Sun-like stars exhibited chromospheric activity levels below solar minimum, which suggest that these stars might be in activity-minimum states analogous to the Maunder Minimum. The activity diagnostic used, the HK index (relative intensities of the Ca ii H and K lines integrated over 1 Å bandpasses), was measured from low-resolution spectra ( R ≈ 5000), as is traditional and suitable for nearby, bright stars. However, for stars beyond the Local Bubble, the interstellar medium (ISM) imprints absorption lines in spectra at Ca ii H and K, which negatively bias activity measurements when these lines fall within the HK index bandpass. I model the ISM clouds in the M67 foreground with high-resolution spectra of blue stragglers and solar analogs. I demonstrate that ISM absorption varies across the cluster and must be accounted for on a star-by-star basis. I then apply the ISM model to a solar spectrum and broaden it to the lower spectral resolution employed by prior surveys. Comparing HK indices measured from ISM-free and ISM-contaminated spectra, I find that all stars observed below solar minimum can be explained by this ISM bias. I conclude that there is no compelling evidence for Maunder Minimum candidates in M67 at this time.

  14. No “Maunder Minimum” Candidates in M67: Mitigating Interstellar Contamination of Chromospheric Emission Lines

    International Nuclear Information System (INIS)

    Curtis, Jason Lee

    2017-01-01

    The solar analogs of M67 let us glimpse the probable behavior of the Sun on timescales surpassing the duration of human civilization. M67 can serve as a solar proxy because its stars share a similar age and composition with the Sun. Previous surveys of M67 observed that 15% of its Sun-like stars exhibited chromospheric activity levels below solar minimum, which suggest that these stars might be in activity-minimum states analogous to the Maunder Minimum. The activity diagnostic used, the HK index (relative intensities of the Ca ii H and K lines integrated over 1 Å bandpasses), was measured from low-resolution spectra ( R ≈ 5000), as is traditional and suitable for nearby, bright stars. However, for stars beyond the Local Bubble, the interstellar medium (ISM) imprints absorption lines in spectra at Ca ii H and K, which negatively bias activity measurements when these lines fall within the HK index bandpass. I model the ISM clouds in the M67 foreground with high-resolution spectra of blue stragglers and solar analogs. I demonstrate that ISM absorption varies across the cluster and must be accounted for on a star-by-star basis. I then apply the ISM model to a solar spectrum and broaden it to the lower spectral resolution employed by prior surveys. Comparing HK indices measured from ISM-free and ISM-contaminated spectra, I find that all stars observed below solar minimum can be explained by this ISM bias. I conclude that there is no compelling evidence for Maunder Minimum candidates in M67 at this time.

  15. Nature and statistical properties of quasar associated absorption systems in the XQ-100 Legacy Survey

    DEFF Research Database (Denmark)

    Perrotta, Serena; D'Odorico, Valentina; Prochaska, J. Xavier

    2016-01-01

    We statistically study the physical properties of a sample of narrow absorption line (NAL) systems looking for empirical evidences to distinguish between intrinsic and intervening NALs without taking into account any a priori definition or velocity cut-off. We analyze the spectra of 100 quasars...

  16. Review on absorption technology with emphasis on small capacity absorption machines

    Directory of Open Access Journals (Sweden)

    Labus Jerko M.

    2013-01-01

    Full Text Available The aim of this paper is to review the past achievements in the field of absorption systems, their potential and possible directions for future development. Various types of absorption systems and research on working fluids are discussed in detail. Among various applications, solar cooling and combined cooling, heating and power (CCHP are identified as two most promising applications for further development of absorption machines. Under the same framework, special attention is given to the small capacity absorption machines and their current status at the market. Although this technology looks promising, it is still in development and many issues are open. With respect to that fact, this paper covers all the relevant aspects for further development of small capacity absorption machines.

  17. Intercomparison of three microwave/infrared high resolution line-by-line radiative transfer codes

    Science.gov (United States)

    Schreier, Franz; Milz, Mathias; Buehler, Stefan A.; von Clarmann, Thomas

    2018-05-01

    An intercomparison of three line-by-line (lbl) codes developed independently for atmospheric radiative transfer and remote sensing - ARTS, GARLIC, and KOPRA - has been performed for a thermal infrared nadir sounding application assuming a HIRS-like (High resolution Infrared Radiation Sounder) setup. Radiances for the 19 HIRS infrared channels and a set of 42 atmospheric profiles from the "Garand dataset" have been computed. The mutual differences of the equivalent brightness temperatures are presented and possible causes of disagreement are discussed. In particular, the impact of path integration schemes and atmospheric layer discretization is assessed. When the continuum absorption contribution is ignored because of the different implementations, residuals are generally in the sub-Kelvin range and smaller than 0.1 K for some window channels (and all atmospheric models and lbl codes). None of the three codes turned out to be perfect for all channels and atmospheres. Remaining discrepancies are attributed to different lbl optimization techniques. Lbl codes seem to have reached a maturity in the implementation of radiative transfer that the choice of the underlying physical models (line shape models, continua etc) becomes increasingly relevant.

  18. Absorber performance of a water/lithium-bromide absorption chiller

    International Nuclear Information System (INIS)

    Xie Guozhen; Sheng Guogang; Bansal, Pradeep Kumar; Li, Guang

    2008-01-01

    An absorber is one of the most important components of a lithium-bromide absorption chiller (LBAC) as its absorbing characteristics directly influence the performance of the whole chiller. It has been indicated that the absorbing efficiency and cooling capacity could be improved by increasing the solution concentration. In this paper, based on the mechanism of falling film absorption on horizontal tubes, the theoretical models of falling film absorption on horizontal tubes have been established. A series of programs used for computing the theoretical mathematical models, including simulation of LBAC cycle and falling film absorption, have been programmed. The models have been validated reasonably by the experimental data. The results show that the cooling capacity of the LBAC varies in parabola shape of curve with the solution concentration from 52.5% to 58.5%, and that the best coefficient of performance (COP) occurs at concentration of 57%. The investigation proposes the absorbing process of sub-steady thermodynamic equilibrium for the duality solution under increase absorbing pressure

  19. The effects of three absorption-modifying critical excipients on the in vivo intestinal absorption of six model compounds in rats and dogs.

    Science.gov (United States)

    David, Dahlgren; Carl, Roos; Pernilla, Johansson; Christer, Tannergren; Anders, Lundqvist; Peter, Langguth; Markus, Sjöblom; Erik, Sjögren; Hans, Lennernäs

    2018-05-11

    Pharmaceutical excipients that may affect gastrointestinal (GI) drug absorption are called critical pharmaceutical excipients (CPEs), or absorption-modifying excipients (AMEs) if they act by altering the integrity of the intestinal epithelial cell membrane. Some of these excipients increase intestinal permeability, and subsequently the absorption and bioavailability of the drug. This could have implications for both the assessment of bioequivalence and the efficacy of the absorption-enhancing drug delivery system. The absorption-enhancing effects of AMEs/CPEs with different mechanisms (chitosan, sodium caprate, sodium dodecyl sulfate (SDS)) have previously been evaluated in the rat single-pass intestinal perfusion (SPIP) model. However, it remains unclear whether these SPIP data are predictive in a more in vivo like model. The same excipients were in this study evaluated in rat and dog intraintestinal bolus models. SDS and chitosan did exert an absorption-enhancing effect in both bolus models, but the effect was substantially lower than those observed in the rat SPIP model. This illustrates the complexity of the AME/CPE effects, and indicates that additional GI physiological factors need to be considered in their evaluation. We therefore recommend that AME/CPE evaluations obtained in transit-independent, preclinical permeability models (e.g. Ussing, SPIP) should be verified in animal models better able to predict in vivo relevant GI effects, at multiple excipient concentrations. Copyright © 2018. Published by Elsevier B.V.

  20. 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.

  1. 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.

  2. In vitro and in vivo percutaneous absorption of retinol from cosmetic formulations: Significance of the skin reservoir and prediction of systemic absorption

    International Nuclear Information System (INIS)

    Yourick, Jeffrey J.; Jung, Connie T.; Bronaugh, Robert L.

    2008-01-01

    The percutaneous absorption of retinol (Vitamin A) from cosmetic formulations was studied to predict systemic absorption and to understand the significance of the skin reservoir in in vitro absorption studies. Viable skin from fuzzy rat or human subjects was assembled in flow-through diffusion cells for in vitro absorption studies. In vivo absorption studies using fuzzy rats were performed in glass metabolism cages for collection of urine, feces, and body content. Retinol (0.3%) formulations (hydroalcoholic gel and oil-in-water emulsion) containing 3 H-retinol were applied and absorption was measured at 24 or 72 h. All percentages reported are % of applied dose. In vitro studies using human skin and the gel and emulsion vehicles found 0.3 and 1.3% retinol, respectively, in receptor fluid at 24 h. Levels of absorption in the receptor fluid increased over 72 h with the gel and emulsion vehicles. Using the gel vehicle, in vitro rat skin studies found 23% in skin and 6% in receptor fluid at 24 h, while 72-h studies found 18% in skin and 13% in receptor fluid. Thus, significant amounts of retinol remained in rat skin at 24 h and decreased over 72 h, with proportional increases in receptor fluid. In vivo rat studies with the gel found 4% systemic absorption of retinol after 24 h and systemic absorption did not increase at 72 h. Retinol remaining in rat skin after in vivo application was 18% and 13% of the applied dermal dose after 24 and 72 h, respectively. Similar observations were made with the oil-in water emulsion vehicle in the rat. Retinol formed a reservoir in rat skin both in vivo and in vitro. Little additional retinol was bioavailable after 24 h. Comparison of these in vitro and in vivo results for absorption through rat skin indicates that the 24-h in vitro receptor fluid value accurately estimated 24-h in vivo systemic absorption. Therefore, the best single estimate of retinol systemic absorption from in vitro human skin studies is the 24-h receptor fluid

  3. Band gap engineering of tandem structured CIGS compound absorption layer fabricated by sputtering and selenization

    International Nuclear Information System (INIS)

    Kang, San; Sharma, Rahul; Sim, Jae-Kwan; Lee, Cheul-Ro

    2013-01-01

    Highlights: ► Systematic band gap engineering to fabricate tandem Cu(In,Ga)Se 2 absorption layers. ► XRD shows prominent (1 1 2) reflection shift for attributed CIS, CIGS, and CGS phases. ► Optical transmittance and reflectance spectrum are improved towards infrared region. ► The Cu/In + Ga and Ga/In + Ga effect is matched with highest efficient solar cell. ► Tandem CIS/CIGS/CGS layer, the band gap is increased from 1.15 to 2.06 eV. -- Abstract: Band gap engineering was executed to fabricate a multi-junction stacked i.e. tandem Cu(In,Ga)Se 2 (CIGS) absorption layer. The CIGS absorption layers consist of multi-junction stacked CIS/CIGS/CGS thin films from bottom to top with increasing band gap. Tandem CIGS layers were fabricated by using three precursor of CuIn, In/CuGa/In, and CuGa onto the Mo coated soda-lime glass (SLG) by the sequential sputtering of CuIn, CuGa, and In targets. The CIG precursors were converted into CIGS absorption thin film by selenization process. From the X-ray diffraction (XRD) pattern of CIS/CIGS/CGS tandem layer, with the prominent peak shift for (1 1 2) reflections was attributed to the individual CIS, CIGS, and CGS phases at 26.76°, 27.15°, and 27.65° diffraction angles, respectively. The morphologies and atomic (at%) composition uniformity onto the surface and along the depth were extensively analyzed with field effect scanning electron microscope (FESEM) attached energy dispersive spectroscopy (EDS) and secondary ion mass spectroscopy (SIMS). The optical properties such as transmittance, reflectance and absorbance were found to improve in the infrared region for all the tandem CIGS layers. Near the fundamental absorption edge, the absorption coefficient was approached to 10 5 cm −1 for CIS/CIGS/CGS tandem layer. The straight-line behavior indicates that the films have a direct band gap. The band gap was found to increase from 1.15 to 1.74 eV with the Ga-grading along the depth of individual CIS, CIGS, and CGS thin films

  4. Infrared Absorption Spectroscopy and Chemical Kinetics of Free Radicals. Final Performance Report, August 1, 1985--July 31, 1994

    Science.gov (United States)

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

    1995-06-01

    This research was directed at the detection, monitoring, and study (by infrared absorption spectroscopy) of the chemical kinetic behavior of small free radical species thought to be important intermediates in combustion. The work typically progressed from the detection and analysis of the infrared spectrum of combustion radical to the utilization of the infrared spectrum thus obtained in the investigation of chemical kinetics of the radical species. The methodology employed was infrared kinetic spectroscopy. In this technique the radical is produced by UV flash photolysis using an excimer laser and then its transient infrared absorption is observed using a single frequency cw laser as the source of the infrared probe light. When the probe laser frequency is near the center of an absorption line of the radical produced by the flash, the transient infrared absorption rises rapidly and then decays as the radical reacts with the precursor or with substances introduced for the purpose of studying the reaction kinetics or with itself. The decay times observed in these studies varied from less than one microsecond to more than one millisecond. By choosing appropriate time windows after the flash and the average infrared detector signal in a window as data channels, the infrared spectrum of the radical may be obtained. By locking the infrared probe laser to the center of the absorption line and measuring the rate of decay of the transient infrared absorption signal as the chemical composition of the gas mixture is varied, the chemical kinetics of the radical may be investigated. In what follows the systems investigated and the results obtained are outlined.

  5. H I absorption in nearby compact radio galaxies

    Science.gov (United States)

    Glowacki, M.; Allison, J. R.; Sadler, E. M.; Moss, V. A.; Curran, S. J.; Musaeva, A.; Deng, C.; Parry, R.; Sligo, M. C.

    2017-05-01

    H I absorption studies yield information on both active galactic nucleus (AGN) feeding and feedback processes. This AGN activity interacts with the neutral gas in compact radio sources, which are believed to represent the young or recently re-triggered AGN population. We present the results of a survey for H I absorption in a sample of 66 compact radio sources at 0.040 100 km s-1) features, indicative of disturbed gas kinematics. Such broad, shallow and offset features are also found within low-excitation radio galaxies which is attributed to disturbed circumnuclear gas, consistent with early-type galaxies typically devoid of a gas-rich disc. Comparing mid-infrared colours of our galaxies with H I detections indicates that narrow and deep absorption features are preferentially found in late-type and high-excitation radio galaxies in our sample. These features are attributed to gas in galactic discs. By combining XMM-Newton archival data with 21-cm data, we find support that absorbed X-ray sources may be good tracers of H I content within the host galaxy. This sample extends previous H I surveys in compact radio galaxies to lower radio luminosities and provides a basis for future work exploring the higher redshift universe.

  6. Diagnosing the reionization of the universe - The absorption spectrum of the intergalactic medium and Lyman alpha clouds

    Science.gov (United States)

    Giroux, Mark L.; Shapiro, Paul R.

    1991-01-01

    The thermal and ionization evolution of a uniform intergalactic medium composed of H and He and undergoing reionization is studied. The diagnosis of the metagalactic ionizing radiation background at z of about three using metal line ratios for Lyman limit quasar absorption line systems is addressed. The use of the He II Gunn-Peterson effect to diagnose the reionization source and/or nature of the Hy-alpha forest clouds is considered.

  7. Folate absorption

    International Nuclear Information System (INIS)

    Baker, S.J.

    1976-01-01

    Folate is the generic term given to numerous compounds of pteroic acid with glutamic acid. Knowledge of absorption is limited because of the complexities introduced by the variety of compounds and because of the inadequacy of investigational methods. Two assay methods are in use, namely microbiological and radioactive. Techniques used to study absorption include measurement of urinary excretion, serum concentration, faecal excretion, intestinal perfusion, and haematological response. It is probably necessary to test absorption of both pteroylmonoglutamic acid and one or more polyglutamates, and such tests would be facilitated by availability of synthesized compounds labelled with radioactive tracers at specifically selected sites. (author)

  8. On-line moisture analysis

    CERN Document Server

    Cutmore, N G

    2002-01-01

    Measurement of the moisture content of iron ore ha