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1

DETECTION OF IRON K{alpha} EMISSION FROM A COMPLETE SAMPLE OF SUBMILLIMETER GALAXIES  

SciTech Connect

We present an X-ray stacking analysis of a sample of 38 submillimeter galaxies (SMGs) with (z) = 2.6 discovered at {>=}4{sigma} significance in the Lockman Hole North with the MAMBO array. We find a 5{sigma} detection in the stacked soft band (0.5-2.0 keV) image, and no significant detection in the hard band (2.0-8 keV). We also perform rest-frame spectral stacking based on spectroscopic and photometric redshifts and find a {approx}4{sigma} detection of Fe K{alpha} emission with an equivalent width of EW {approx}> 1 keV. The centroid of the Fe K{alpha} emission lies near 6.7 keV, indicating a possible contribution from highly ionized Fe XXV or Fe XXVI; there is also a slight indication that the line emission is more spatially extended than the X-ray continuum. This is the first X-ray analysis of a complete, flux-limited sample of SMGs with statistically robust radio counterparts.

Lindner, Robert R.; Baker, Andrew J. [Rutgers, State University of New Jersey, 136 Frelinghuysen Road, Piscataway, NJ 08854-8019 (United States); Beelen, Alexandre [Institut d'Astrophysique Spatiale, Universite Paris Sud 11 and CNRS, F-91405 Orsay (France); Owen, Frazer N. [National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801 (United States); Polletta, Maria, E-mail: lindner@physics.rutgers.edu, E-mail: ajbaker@physics.rutgers.edu, E-mail: alexandre.beelen@ias.u-psud.fr, E-mail: fowen@nrao.edu, E-mail: polletta@iasf-milano.inaf.it [INAF-IASF Milano, via E. Bassini, I-20133 Milan (Italy)

2012-09-20

2

Effect of laser energy and incidence angle on K-alpha and bremsstrahlung emission from thin foil targets irradiated by a short pulse, high intensity laser  

NASA Astrophysics Data System (ADS)

We report on experiments performed to characterize a short pulse, high intensity, laser-produced x-ray source for diffraction studies. These experiments were performed using the Titan laser at the Jupiter Laser facility with a 40ps pulse length at intensities varying from 10?16 to 10?18 W/cm?2. The targets were 12 micron thick silver foils. The effects of the laser pulse energy, target angle and spot size on x-ray emission were measured using single photon counting cameras CCD cameras and bremsstrahlung spectrometers arranged upstream, downstream, and orthogonal to the laser. Integrated Tiger Series (ITS), a Monte Carlo code, was used to model the K-shell spectra and bremsstrahlung emission from the target, as well as the response of the bremsstrahlung spectrometers. Absolute k-alpha photon yields and k-alpha to bremsstrahlung ratios as a function of laser pulse energy and the angle between the laser and the target surface were determined; these data are crucial for designing picosecond x-ray diffraction experiments on Omega EP and the NIF.

Westover, Bradley; Macphee, Andrew; Ma, Tammy; Beg, Farhat; Chen, Cliff; Hey, Daniel; Maddox, Brian; Park, Hye-Sook; Remington, Bruce

2008-11-01

3

Multiconfiguration Dirac-Fock calculations in open-shell atoms: Convergence methods and satellite spectra of the copper K{alpha} photoemission spectrum  

SciTech Connect

The copper K{alpha} photoemission spectra is one of the most widely studied. Recent Dirac-Fock calculations have produced transition energies in good agreement with experiment, though they have relied on approximations that may not be transferable to other complex atoms in which uncertainties in theoretical results are dominated by poor convergence. Through a detailed examination of convergence issues in the copper spectrum, we consider the accuracy obtainable with the multiconfiguration Dirac-Fock (MCDF) method, provide the first determination of fine structure contributions to the spectrum, and demonstrate reliable techniques for modeling spectator states with vacancies in the 3p, 3d, and 4s shells.

Chantler, C. T.; Lowe, J. A.; Grant, I. P. [School of Physics, University of Melbourne, Victoria 3101 (Australia); Mathematical Institute, Oxford University, Oxford (United Kingdom)

2010-11-15

4

Analysis of molecular emission spectra  

Microsoft Academic Search

Rich emission spectra are typically observed in the study of post-breakdown plasma phenomena subsequent to laser-induced breakdown of, for example, air. The application of line strengths for various diatomic molecules in non-linear fitting algorithms allows us to infer primarily the temperature at different delay times from optical breakdown. Here we present results of Monte Carlo simulations of different sources of

Guoming Guan; Christian Parigger; Jim Hornkohl; Jim W. L. Lewis

1997-01-01

5

Analysis of molecular emission spectra  

NASA Astrophysics Data System (ADS)

Rich emission spectra are typically observed in the study of post-breakdown plasma phenomena subsequent to laser-induced breakdown of, for example, air. The application of line strengths for various diatomic molecules in non-linear fitting algorithms allows us to infer primarily the temperature at different delay times from optical breakdown. Here we present results of Monte Carlo simulations of different sources of noise in recorded hydroxyl (OH) spectra in order to estimate the reliability and error bars of the fitted set of parameters. Of particular interest is the information content of sections of a measured spectrum for precise evaluations of, for example, rotational and vibrational temperatures. In addition, results are presented of computations by the use of the recently made available code for nonequilibrium air radiation (NEQAIR) which allows us to also estimate number densities of OH and various other species.

Guan, Guoming; Parigger, Christian; Hornkohl, Jim; Lewis, Jim W. L.

1997-11-01

6

The role of hot electron refluxing in laser-generated K-alpha sources  

NASA Astrophysics Data System (ADS)

A study of the contribution of refluxing electrons in the production of K-alpha radiation from high-intensity laser irradiated thin targets has been performed. Thin copper foils both freestanding, and backed by a thick substrate were irradiated with laser pulses of energies around 100 J at intensities ranging from below 1017 to above 1019 W/cm2. At high laser intensities we find a strong reduction in the K-alpha yield from targets backed by the substrate. The observed yield reduction is in good agreement with a simple model using hot electron spectra from particle-in-cell simulations or directly inferred from the measured bremsstrahlung emission and can therefore be interpreted as due to the suppression of hot electron refluxing. The study shows that refluxing electrons play a dominant role in high-intensity laser driven K- alpha generation and have to be taken into account in designing targets for laser driven high-flux K-alpha sources.

Neumayer, P.; Aurand, B.; Basko, M.; Ecker, B.; Gibbon, P.; Hochhaus, D. C.; Karmakar, A.; Kazakov, E.; Khl, T.; Labaune, C.; Rosmej, O.; Tauschwitz, An.; Zielbauer, B.; Zimmer, D.

2010-10-01

7

The Emission Spectra of Various Thermoluminescent Materials.  

National Technical Information Service (NTIS)

The thermoluminescence emission spectra of various materials were determined using a quartz-prism spectrograph. The materials studied include: CaF2:Mn, CaSO4:Mn, Li2B4O7:Mn, LiF(TLD-100), CaF2(MBLE), and a terbium-activated lithium-aluminosilicate thermol...

S. G. Gorbics

1966-01-01

8

Effect of Aluminum Substitution on the Emissivity Spectra of Hematite  

NASA Astrophysics Data System (ADS)

There are small differences in the emissivity spectra of the martian hematite found in Sinus Meridiani, Aram Chaos, and Valles Marineris. We report here on the effects of aluminum substitution on the emissivity spectra of hematite.

Glotch, T. D.; Morris, R. V.; Christensen, P. R.

2002-03-01

9

Effect of Aluminum Substitution on the Emissivity Spectra of Hematite  

Microsoft Academic Search

There are small differences in the emissivity spectra of the martian hematite found in Sinus Meridiani, Aram Chaos, and Valles Marineris. We report here on the effects of aluminum substitution on the emissivity spectra of hematite.

T. D. Glotch; R. V. Morris; P. R. Christensen

2002-01-01

10

Martian Analogues Emissivity Spectra From the Berlin Emissivity Database (BED)  

NASA Astrophysics Data System (ADS)

Remote sensing infrared spectroscopy is the principal field of investigation for planetary surfaces composition. Past, present and future missions to bodies in the solar system include in their payload instruments measuring the emerging radiation in the infrared range. For the interpretation of the measured data an emissivity spectral library of planetary analog materials is needed. The Berlin Emissivity Database (BED) currently contains emissivity spectra of plagioclase and potassium feldspars, low Ca and high Ca pyroxenes, olivine, elemental sulphur, and Martian analogue minerals, measured in the wavelength range from 7 to 22 microns as a function of particle size. For each sample we measured the spectra of four particle size separates ranging from 0 to 250 microns. The device we used is built at DLR (Berlin) and is coupled to a Fourier transform infrared spectrometer (Bruker IFS 88), purged with dry air and equipped with a cooled detector (MCT). All spectra were acquired with a spectral resolution of 4 cm-1. We present here the results of our analysis on well knew and characterized Martian analogue minerals: JSC Mars-1, Salten Skov, and Palagonite from Mauna Kea, Hawaii. We are currently working to upgrade our emissivity facility. A new spectrometer (Bruker VERTEX 80v) and new detectors will allow us to measure the emissivity of samples in the wavelength range from 1 to 50 microns, even in a vacuum environment.

Maturilli, A.; Helbert, J.; Moroz, L.

2006-12-01

11

Characteristic Visible Fluorescence Emission Spectra of Sera from Cancer Patients  

Microsoft Academic Search

The feasibility of using visible fluorimetry as a simple spectroscopic method for cancer diagnosis and\\/or management was investigated by recording the visible fluorescence emission spectra of sera from cancer patients and healthy individuals. Characteristic visible fluorescence emission spectra were found to occur in sera of some cancer patients, e.g., patients with breast or lung cancer, with spectral features similar to

Joseph H. Aiken; Carmen W. Huie; James A. Terzian

1994-01-01

12

Comparison of experimental and simulated K{alpha} yield for 400 nm ultrashort pulse laser irradiation  

SciTech Connect

Ti K{alpha} emission yields from foils irradiated with {approx}45 fs, p-polarized pulses of a frequency-doubled Ti:sapphire laser are presented. A simple model invoking vacuum heating to predict absorption and hot electron temperature was coupled with the cross section for K-shell ionization of Ti and the Bethe-Bloch stopping power equation for electrons. The peak predicted K{alpha} emission was in generally good agreement with experiment. This contrasts strongly with previous work at the fundamental frequency. Similar predictions using particle-in-cell (PIC) code simulation to estimate the number and temperature of hot electrons also gave good agreement for yield.

Khattak, F. Y.; Percie du Sert, O. A. M. B.; Riley, D.; Foster, P. S.; Divall, E. J.; Hooker, C. J.; Langley, A. J.; Smith, J.; Gibbon, P. [School of Mathematics and Physics, Queen's University of Belfast, University Road, Belfast BT7 1NN (United Kingdom); Central Laser Facility, CLRC Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX (United Kingdom); John von Neumann Institute for Computing, Central Institute for Applied Mathematics (ZAM), Computer Simulations Division, Research Centre Juelich, D-52425 Juelich (Germany)

2006-08-15

13

12.6 keV Kr K-alpha X-ray Source For High Energy Density Physics Experiments  

SciTech Connect

A high contrast 12.6 keV Kr K{alpha} source has been demonstrated on the petawatt-class Titan laser facility. The contrast ratio (K{alpha} to continuum) is 65, with a competitive ultra short pulse laser to x-ray conversion efficiency of 10{sup -5}. Filtered shadowgraphy indicates that the Kr K{alpha} and K{beta} x-rays are emitted from a roughly 1 x 2 mm emission volume, making this source suitable for area backlighting and scattering. Spectral calculations indicate a typical bulk electron temperature of 50-70 eV (i.e. mean ionization state 13-16), based on the observed ratio of K{alpha} to K{beta}. Kr gas jets provide a debris-free high energy K{alpha} source for time-resolved diagnosis of dense matter.

Kugland, N; Constantin, C G; Niemann, C; Neumayer, P; Chung, H; Doppner, T; Kemp, A; Glenzer, S H; Girard, F

2008-04-22

14

Extreme ultraviolet emission spectra of Gd and Tb ions  

SciTech Connect

Theoretical extreme ultraviolet emission spectra of gadolinium and terbium ions calculated with the Cowan suite of codes and the flexible atomic code (FAC) relativistic code are presented. 4d-4f and 4p-4d transitions give rise to unresolved transition arrays in a range of ions. The effects of configuration interaction are investigated for transitions between singly excited configurations. Optimization of emission at 6.775 nm and 6.515 nm is achieved for Gd and Tb ions, respectively, by consideration of plasma effects. The resulting synthetic spectra are compared with experimental spectra recorded using the laser produced plasma technique.

Kilbane, D.; O'Sullivan, G. [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland)

2010-11-15

15

Wide-Band Spectra of Prompt Emission  

NASA Astrophysics Data System (ADS)

The Fermi observatory has detected GeV photons from several GRBs. Some of them show an extra spectral component, which is a hint for emission mechanism of GRBs. Here we discuss the GeV emission mechanism according to several promising models. The difference between models will appear in temporal evolution of the photon spectrum. To verify this, instruments that can obtain high photon statistics like CTA are desired. We also discuss the photosphere model, which is recently supported by wide-band observations with Fermi.

Asano, K.

2013-07-01

16

FIGARO : measuring neutron emission spectra with a white neutron source /.  

SciTech Connect

Neutron emission spectra from reactions induced by fast neutrons are of importance in basic physics and applications. Very few data are available in the literature over a wide range of incident neutron energies such as produced with a white neutron source. The FIGARO facility at the WNR/LANSCE neutron source has been established to measure such neutron emission over a range of incident neutron energies from 1 to over 100 MeV. Using the time-of-flight technique twice (once to determine the incident neutron energy and again to determine the outgoing neutron energy), we are measuring neutron emission spectra for several reactions such as (n,n') and (n,f). Neutron emission from inelastic scattering gives information on the level density of excited states of the target nucleus. Our first measurements are on structural materials such as iron.

Haight, Robert C.; O'Donnell, J. M.; Zanini, L.; Devlin, M.; Rochman, D. (Dimitri)

2002-01-01

17

Production of copper(I) halide emission spectra by MECA  

Microsoft Academic Search

THE introduction of copper (II) salts into most commonly used flames gives a green emission. Copper halides give a particularly intense emission, which is used in the well-known Beilstein test for halogens. The spectra from all copper salts, however, are very similar, and consist mainly of diffuse CuOH bands in the region 535-555 nm, a CuH band centred around 429

R. Belcher; S. L. Bogdanski; S. A. Ghonaim; A. Townshend

1974-01-01

18

Investigation of Fe xv Emission Lines in Solar Flare Spectra.  

National Technical Information Service (NTIS)

Previously, large discrepancies have been found between theory and observation for Fe xv emission line ratios in solar flare spectra covering the 224-327 Angstrom wavelength range, obtained by the Naval Research Laboratory's S082A instrument on board Skyl...

A. Z. Msezane D. S. Bloomfield F. P. Keenan K. G. Widing K. M. Aggarwal

2008-01-01

19

A Correlation Between Stellar Activity and Hot Jupiter Emission Spectra  

NASA Astrophysics Data System (ADS)

We present evidence for a correlation between the observed properties of hot Jupiter emission spectra and the activity levels of the host stars measured using Ca II H & K emission lines. We find that planets with dayside emission spectra that are well-described by standard one-dimensional atmosphere models with water in absorption (HD 189733, TrES-1, TrES-3, WASP-4) orbit chromospherically active stars, while planets with emission spectra that are consistent with the presence of a strong high-altitude temperature inversion and water in emission orbit quieter stars. We estimate that active G and K stars have Lyman ? fluxes that are typically a factor of 4-7 times higher than quiet stars with analogous spectral types and propose that the increased UV flux received by planets orbiting active stars destroys the compounds responsible for the formation of the observed temperature inversions. In this paper, we also derive a model-independent method for differentiating between these two atmosphere types using the secondary eclipse depths measured in the 3.6 and 4.5 ?m bands on the Spitzer Space Telescope and argue that the observed correlation is independent of the inverted/non-inverted paradigm for classifying hot Jupiter atmospheres. Based on observations obtained at the W. M. Keck Observatory, which is operated jointly by the University of California and the California Institute of Technology. Keck time has been granted by both NASA and the University of California.

Knutson, Heather A.; Howard, Andrew W.; Isaacson, Howard

2010-09-01

20

Emission features in IRAS LRS spectra of M Mira variables  

SciTech Connect

A total of 291 M Mira variables with IRAS low-resolution spectrometer (LRS) spectra that have 8-micron fluxes greater than 15 Jy have been analyzed. After subtraction of a 2500 K blackbody energy distribution from the spectrum, the remaining difference spectra can be classified into seven groups, depending on the shape of their spectral emission features around 10 microns: Sil, Sil(+) Sil(2+), S, three-component, 'broad', and no feature. The spectral emission features are interpreted as being produced primarily by amorphous silicates with differing amounts of crystalline olivine. A weak broad feature at 9-13 microns is possibly produced by aluminum oxide and/or a size distribution of silicate particles that favors larger grains. The 8-22-micron IR excess, defined as the fraction of energy above the 2500 K continuum, shows only a slight tendency to correlate with period and no tendency to correlate with mass loss rate. Maser emission from OH and H2O is much more frequently detected in stars that show the Sil or Sil(+) emission feature, but SiO maser emission is detected with the same percentage in all emission feature classes with the exception of the S feature. Stars showing the S feature appear to be closely related to the MS and S stars. 33 refs.

Little-marenin, I.R.; Little, S.J. (Whitin Observatory, Wellesley, MA (USA) Bentley College, Waltham, MA (USA))

1990-04-01

21

Software tools for the analysis of video meteors emission spectra  

NASA Astrophysics Data System (ADS)

One of the goals of the SPanish Meteor Network (SPMN) is related to the study of the chemical composition of meteoroids by analyzing the emission spectra resulting from the ablation of these particles of interplanetary matter in the atmosphere. With this aim, some of the CCD video devices we employ to observe the nigh sky are endowed with holographic diffraction gratings, and a continuous monitoring of meteor activity is performed. We have recently developed a new software to analyze these spectra. A description of this computer program is given, and some of the results obtained so far are presented here.

Madiedo, J. M.; Toscano, F. M.; Trigo-Rodriguez, J. M.

2011-10-01

22

A Thermal Infrared Emission Spectra Library for Unpowdered Meteorites  

Microsoft Academic Search

Mid-infrared thermal emission spectra have been obtained for whole-rock (unpowdered) samples of the following 25 meteorites: Abee, Admire, Allende, Bondoc, Brahin, Bruderheim, Canyon Diablo, Carichic, Clover Springs, Dhofar 007, Estherville, Holbrook, Juancheng, Kapoeta, Long Island, Marion, Modoc, ALH77225, ALH77233, ALH84082, LEW85322, ALH85025, ALH79029, ALH77004, and LEW86015. Meteorites were provided through the Center for Meteorite Studies at ASU, Johnson Space Center

J. W. Ashley; P. R. Christensen

2007-01-01

23

Optical spectra of narrow emission line Palomar-Green galaxies  

Microsoft Academic Search

Spectra were obtained of 35 of the 36 narrow emission line galaxies isolated in the Palomar-Green (PG) survey of Green, Schmidt, and Liebert (1986). Of these, three are narrow-line Seyfert 1 galaxies, three more are Seyfert 1.5 galaxies, and only one, PG 2259 + 157 = NGC 7465 = Mrk 313, is a relatively low-ionization active galactic nucleus, a marginal

Donald E. Osterbrock; Richard W. Pogge

1987-01-01

24

Study of temporal variations of solar chromospheric emission spectra  

Microsoft Academic Search

Temporal variations were studied in the emission features in the cores of the Ca II, H, and K Fraunhofer lines and in the wavelength 396.94 nm line of Fe II from April 1980 to November 1982. High resolution spectra were obtained with a 1.8 m focal length Ebert-Fastie monochromator in the neighborhoods of the cores of the H and K

Patrick Gerard Lonergan

1986-01-01

25

Terrestrial FeO Continuum Emission Observed in Sky Spectra  

NASA Astrophysics Data System (ADS)

The terrestrial continuum emission in the visible spectral region has often been studied by both astronomers and aeronomers, in order to clarify backgrounds and the nature of the emissions. New observations from the ESI spectrograph on the Keck II telescope, as well as from the OSIRIS/Odin spectrograph and orbiter, have established that a major component of the emission originates with the FeO molecule [Evans et al., 2010]. This quasi-continuum peaks at 5950 A and extends from 5000 A well into the infrared. The identity has been demonstrated by comparison with meteor trains and laboratory measurements [Jenniskens et al., 2000]. Early studies of the continuum show consistency with the FeO emission as presently observed [Gadsden and Marovich, 1973]. Analysis of spectra from Kitt Peak [Neugent and Massey, 2010] demonstrates the great similarity between FeO emission in a clean atmosphere and high pressure sodium lamp emission in a polluted atmosphere. This research was supported by NSF Aeronomy under Grant ATM-0637433 . Evans, W.F.J., et al., Geophys. Res. Lett. [in press, 2010] Gadsden, M. and E. Marovich, J. Atm. Terr. Phys., 35, 1601-1614 [1973] Jenniskens, P., et al., Earth, Moon and Planets, 82-83, 429-434 [2000] Neugent, K.F. and P. Massey, PASP [in press, 2010

Slanger, Tom G.; Melchiorri, R.; Saran, D. V.

2011-01-01

26

New vibrational bands in nitrogen laser emission spectra  

NASA Astrophysics Data System (ADS)

Nitrogen laser emission spectra was analyzed using a 0.5-m Jarrell-Ash monochromator. In addition to the (0,0) 337.1-nm band, the laser spectra were found to contain (0,1) 357.69-nm, (2,4) 371.05-nm, (1,0) 315.93-nm, (0,2) 380.49-nm, (0,3) 405.94-nm, (1,3) 375.54-nm, (1,4) 399.84-nm, and (1,2) 353.67-nm bands belonging to the second positive system of the N2 molecule. A new transition from one of the mixed vibrational levels of C and C' states of the N2 molecule was observed in the laser spectra at 331.83 nm with a relative intensity of about 29 percent. Two bands, at 340.85 and 303.49 nm, belonging to the beta system of the NO molecule were also observed. The intensity variation of the prominent bands observed was studied with respect to change in operating pressure and voltage for deriving the optimum conditions for emission at these wavelengths.

Subhash, N.; Kartha, S. C.; Sathianandan, K.

1983-11-01

27

Helium shells and faint emission lines from slitless flash spectra  

NASA Astrophysics Data System (ADS)

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

Bazin, Cyril; Koutchmy, Serge

2013-05-01

28

Study of temporal variations of solar chromospheric emission spectra  

NASA Astrophysics Data System (ADS)

Temporal variations were studied in the emission features in the cores of the Ca II, H, and K Fraunhofer lines and in the wavelength 396.94 nm line of Fe II from April 1980 to November 1982. High resolution spectra were obtained with a 1.8 m focal length Ebert-Fastie monochromator in the neighborhoods of the cores of the H and K lines. The relative intensities and positions of the emission features in the cores of the H and K lines were measured along with the intensity of the wavelength 396.94 nm line of Fe II. Tests were made of possible correlations between standard parameters of solar magnetic activity and the spectral data in order to study the possibility of using Ca II, H, and K core emission measurements as a gauge of magnetic activity in other stars. A search for periodicities in the spectral as well as in the standard solar data during this time period was done as a further test of such correlations; as well as to establish a possible method for determining stellar rotation periods. Significant correlations were found between the K line emission feature positions and the sunspot number, the Ca II plage index, and the 2800 MHz emissions. A periodicity corresponding to the solar rotation period was found in all of the Ca II observations with the K line data giving results with the best signal-to-noise ratios.

Lonergan, Patrick Gerard

1986-09-01

29

Far infrared emission spectra from stratospheric hydrogen peroxide  

SciTech Connect

Synthetic emission spectra from two stratospheric altitude observations have been analyzed for the presence of H{sub 2}O{sub 2} in the far infrared region. The calculations are made with a high spectral resolution (10{sup {minus}3} cm{sup {minus}1} or 10{sup {minus}4} cm{sup {minus}1}) greater than those in experimental measurements which are in the region of 3.10{sup {minus}3} cm{sup {minus}1}. Spectra cover a spectral interval between 40 and 120 cm{sup {minus}1} showing the best features of H{sub 2}O{sub 2} susceptible to observation in a stratospheric spectrum. The optimum conditions for identification have been considered. Using the variations in H{sub 2}O{sub 2} abundance in the measurement data and photochemical models, the H{sub 2}O{sub 2} features detection limits have been studied.

Rebours, B. [Universite de Rennes, Lannion (France)

1995-09-01

30

Analysis of time-resolved emission spectra of oriented phycobilisomes.  

PubMed

The polarized time-resolved (in ps range) fluorescence spectra of phycobilisomes obtained from cyanobacteria Tolypothrix tenuis embedded in poly(vinyl alcohol) films and oriented by film stretching have been analysed. Fluorescence spectra were deconvoluted on Gaussian components supposing the same positions of components maxima in three sets of time-resolved spectra taken in natural and polarized light. A good fit of the experimental and calculated spectra was obtained when using the following maxima: 580 and 595 nm in the phycoerythrin region, 634 and 650 nm in the phycocyanin region, 660 and 680 nm in the allophycocyanin region. The area under curve of the Gaussian component vs. time gives the shape of rise and decay of emission of chromophores contributing to the given component. These kinetics were analysed using several model functions. The experimental excitation profile was convoluted with a multiexponential model individually or "globally" e.g. assuming the same lifetime values for the given species in all sets of spectra. The Foerster-Hauser types of two- and three-dimensional models we also convoluted with excitation profile and fitted to the decay of primarily excited species. The first acceptor decay can be described well by the Foerster-Hauser models or by a monoexponential function. The accuracy of fit in either case of three- and two-dimensional Foerster-Hauser function is similar. The fluorescence rise and decay of the next species in a donor-acceptor chain can be analysed in terms of two or three exponential functions. Obtained lifetimes of fluorescence are similar to those reported in literature. The results suggest that there are more than one chain of excitation donors and acceptors in the phycobilisomes of cyanobacteria Tolypothrix tenuis. PMID:17014799

Frackowiak, D; Kowalczyk, A; Skibi?ski, A

1992-02-01

31

Atmospheric Atomic Emissions in Keck/HIRES Night Sky Spectra  

NASA Astrophysics Data System (ADS)

The unsurpassed resolution and sensitivity of the HIRES spectrograph at the 10-m Keck I telescope creates new opportunities for investigation of the emissions of the Earth's atmosphere, providing unanticipated benefits from data collected incidentally by astronomers. In return, aeronomers can assist the astronomy community in disentangling terrestrial and extraterrestrial sources. Here we report recent analysis of atomic emissions: H(4340, 4861, 6563), N(5198, 5200), O(5577, 6300, 6364, 7774, 8446), Na(5890, 5896), K(7699), and Hg(4047, 4358, 5461) (all wavelengths in { Angstroms}). For the nitrogen lines the Keck/HIRES wavelengths are the best available, and differ from published values by 0.02 { Angstroms}. The stronger emissions are well known, with intensities that typically range from about 1 R (Rayleigh) for N, to 2 R for H(6563), 60 R for Na, 100 R for O(6300, 6364), and 200 R for O(5577). The weaker lines are still conspicuous in the Keck/HIRES spectra: H(4340) about 50 mR, O(8446) 150 mR, Hg 200 mR, H(4861) 250 mR, O(7774) 350 mR, and K 1.5 R. Previous aeronomy studies suggest production mechanisms, characteristic altitudes, and time-of-night dependences for the atomic emissions. Some, e.g. O(5577), Na, and K, are produced by chemical processes near the mesopause (95 km) that are relatively constant during the night. Others, N, O(6300, 6364, 7774, 8446), are produced by electron-ion recombination in the ionosphere (120-400 km), with intensities that decrease rapidly after twilight. The hydrogen emissions are attributed to solar-excited fluorescence in the geocorona. The mercury emissions are probably scattered city light. Supported by NSF Astronomy and Aeronomy and NASA Sun-Earth Connection. The W. M. Keck Observatory is operated by the California Institute of Technology and the University of California.

Huestis, D. L.; Cosby, P. C.; Slanger, T. G.; Osterbrock, D. E.; Waters, R.

1999-05-01

32

DISCOVERY OF STRONG IRON K{alpha} EMITTING COMPTON THICK QUASARS AT z = 2.5 AND 2.9  

SciTech Connect

We report the detection of the 6.4 keV iron K{alpha} emission line in two infrared-luminous, massive, star-forming BzK galaxies at z = 2.578 and z = 2.90 in the CDF-S. The Chandra 4 Ms spectra of BzK 4892 and BzK 8608 show a reflection-dominated continuum with strong iron lines, with rest-frame equivalent widths EW {approx} 2.3 keV and 1.2 keV, respectively, demonstrating Compton thick (CT) obscuration of the central active galactic nucleus (AGN). For BzK 8608, the line identification closely matches the existing photometric redshift derived from the stellar emission. We use the observed luminosities of the iron K{alpha} line, of the rest-frame mid-IR continuum and of the UV rest-frame narrow emission lines to infer intrinsic L{sub 2-10}{sub keV} {approx}> 10{sup 44} erg s{sup -1}, about 1.0-2.5 dex larger than the observed ones, hence confirming the presence of an absorber with N{sub H}>10{sup 24} cm{sup -2}. The two BzK galaxies have stellar masses of 5 x 10{sup 10} M{sub sun} and, based on Very Large Array 1.4 GHz and submillimeter 870 {mu}m observations, they appear to host vigorous starburst activity with star formation rate {approx} 300-700 M{sub sun} yr{sup -1} that is also optically thick. We estimate that the AGN might also conceivably account for an important fraction of the bolometric far-IR emission of the galaxies. The implied volume density of CT AGN with L{sub 2-10}{sub keV}>10{sup 44} erg s{sup -1} is in agreement with predictions from X-ray background synthesis models. These sources provide one of the first clear-cut observations of the long-sought phase of simultaneous, heavily obscured quasar and star formation activity, predicted by models of massive galaxy evolution at high redshifts.

Feruglio, C.; Daddi, E. [Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot, Irfu/Service d'Astrophysique, CEA Saclay, Orme des Merisiers, 91191 Gif-sur-Yvette Cedex (France); Fiore, F.; Piconcelli, E. [INAF-Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monteporzio Catone (Italy); Alexander, D. M. [Department of Physics, Durham University, South Road, DH1 3LE (United Kingdom); Malacaria, C., E-mail: chiara.feruglio@cea.fr [Universita' La Sapienza, Piazzale Aldo Moro 5, 00185 Roma (Italy)

2011-03-01

33

K{alpha} yields from Ti foils irradiated with ultrashort laser pulses  

SciTech Connect

We have studied the emission of K{alpha} radiation from Ti foils irradiated with ultrashort (45 fs) laser pulses. We utilized the fundamental (800 nm) light from a Ti:sapphire laser on bare foils and foils coated with a thin layer of parylene E (CH). The focusing was varied widely to give a range of intensities from approximately 10{sup 15}-10{sup 19} W cm{sup -2}. Our results show a conversion efficiency of laser to K{alpha} energy of {approx}10{sup -4} at tight focus for both types of targets. In addition, the coated targets exhibited strong secondary peaks of conversion at large defocus, which we believe are due to modification of the extent of preformed plasma due to the dielectric nature of the plastic layer. This in turn affects the level of resonance absorption. A simple model of K{alpha} production predicts a much higher conversion than seen experimentally and possible reasons for this are discussed.

Riley, D.; Angulo-Gareta, J.J.; Khattak, F.Y.; Lamb, M.J.; Foster, P.S.; Divall, E.J.; Hooker, C.J.; Langley, A.J.; Clarke, R.J.; Neely, D. [School of Mathematics and Physics, Queen's University of Belfast, University Road, Belfast, BT7 1NN, Northern Ireland (United Kingdom); Central Laser Facility, CLRC Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, OX11 0QX (United Kingdom)

2005-01-01

34

K-alpha conversion efficiency measurments for x-ray scattering in inertial confinement fusion plasmas  

SciTech Connect

The conversion efficiency of ultra short-pulse laser radiation to K-{alpha} x-rays has been measured for various chlorine-containing targets to be used as x-ray scattering probes of dense plasmas. The spectral and temporal properties of these sources will allow spectrally-resolved x-ray scattering probing with picosecond temporal resolution required for measuring the plasma conditions in inertial confinement fusion experiments. Simulations of x-ray scattering spectra from these plasmas show that fuel capsule density, capsule ablator density, and shock timing information may be inferred.

Kritcher, A L; Neumayer, P; Urry, M K; Robey, H; Niemann, C; Landen, O L; Morse, E; Glenzer, S H

2006-11-21

35

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

NASA Astrophysics Data System (ADS)

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

Judge, P. G.; Jordan, C.

1991-09-01

36

Fine structure splitting in argon x-ray emission spectra  

SciTech Connect

X-ray emission spectrometry is a method of growing importance for a large number of problems in physics and applications in other fields, e.g. investigations of heavy ion sources, plasma diagnostics in connection with fusion research, astrophysics and basic research in other fields of physics. However, there is a lack of data required for the interpretation of spectra obtained especially in the region of highly ionized atoms. Since this is mainly caused by experimental difficulties, theoretical calculations are required to provide data that are necessary for the current studies. Therefore, the authors developed a program package to calculate various atomic properties of neutral and ionized atoms. In the present paper they analyze, how the fine structure splitting influences the x-ray spectrum emitted by atoms of a given element at various stages of ionization.

Reiche, I.; Fritzsche, S.; Musiol, G.; Zschornack, G. (Technische Univ. Dresden (Germany))

1989-05-01

37

Valence Band X-Ray Emission Spectra of Compressed Germanium  

SciTech Connect

We report measurements of the valence band width in compressed Ge determined from x-ray emission spectra below the Ge K edge. The width of the valence band does not show any pressure dependence in the semiconducting diamond-type structure of Ge below 10 GPa. On the other hand, in the metallic {beta}-Sn phase above 10 GPa the valence band width increases under compression. Density-functional calculations show an increasing valence band width under compression both in the semiconducting phase (contrary to experiment) and in the metallic {beta}-Sn phase of Ge (in agreement with observed pressure-induced broadening). The pressure-independent valence band width in the semiconducting phase of Ge appears to require theoretical advances beyond the density-functional theory or the GW approximation.

Struzhkin, Viktor V.; Mao Hokwang; Lin Jungfu; Hemley, Russell J. [Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road NW, Washington, DC 20015 (United States); Tse, John S.; Ma Yanming [Steacie Institute for Molecular Science, National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario, K1A 0R6 (Canada); Hu, Michael Y.; Chow, Paul [HPCAT, Carnegie Institution of Washington, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Kao Chichang [NSLS, Brookhaven National Laboratory, Upton, New York 11973 (United States)

2006-04-07

38

Study of Dynamic Emission Spectra from Lubricant Films in an Elastohydrodynamic Contact Using Fourier Transform Spectroscopy.  

National Technical Information Service (NTIS)

Infrared emission spectra were obtained through a diamond window from lubricating fluids in an operating sliding elastohydrodynamic contact and analyzed by comparison with static absorption spectra under similar pressures. Different loads, shear rates and...

J. L. Lauer

1978-01-01

39

Fluorescence emission spectra of calcofluor stained yeast cell suspensions: heuristic assessment of basis spectra for their linear unmixing.  

PubMed

Fluorescence emission spectra of yeast cell suspensions stained with calcofluor have recently been identified as promising markers of variations in the quality of yeast cell wall. It is shown in this paper how the raw fluorescence spectra of calcofluor can be transformed to reliable spectral signatures of cell wall quality, which are independent of actual dye-to-cell concentrations of examined cell suspensions. Moreover, the presented approach makes it possible to assess basis fluorescence spectra that allows for the spectral unmixing of raw fluorescence spectra in terms of respective fluorescence contributions of calcofluor solvated in the suspension medium and bound to yeast cell walls. PMID:22538834

Plek, Jaromr; Dostl, Marek; Gkov, Dana

2012-04-27

40

Intense ion beam K alpha measurements on PBFA-II  

Microsoft Academic Search

Inertial Confinement Fusion research efforts at Sandia National Laboratories center around generating and focusing high intensity light ion beams on the Particle Beam Fusion Accelerator PBFA-II. A time-integrating three-frame ion beam spatial monitor was developed for these experiments to determine proton and lithium ion beam uniformity and orbit characteristics by imaging the ion-induced K-alpha line radiation. The three views of

J. Maenchen; T. A. Mehlhorn; D. F. Wenger; R. J. Leeper; D. J. Johnson; T. R. Lockner

1988-01-01

41

Study of silver K{alpha} and bremsstrahlung radiation from short-pulse laser-matter interactions with applications for x-ray radiography  

SciTech Connect

Measurements of K{alpha} radiation yield and x-ray bremsstrahlung emission from thin-foil silver targets are presented. The targets were irradiated by a short pulse laser with intensities from 5x10{sup 16} to 10{sup 18} W/cm{sup 2} at 40 ps. Single hit charge-coupled device detectors, differential filter-stack detectors, and a crystal spectrometer were used to investigate the angular distribution of the K{alpha} and bremsstrahlung x-rays. This study is the first to use a broadband detector to estimate the absolute numbers of K{alpha} photons and to determine K{alpha} to bremsstrahlung ratios. The relevance of this work in the context of x-ray diffraction and x-ray radiography is discussed.

Westover, B.; Beg, F. N. [Center for Energy Research, University of California, San Diego, California 92093-0411 (United States); MacPhee, A.; Chen, C.; Hey, D.; Maddox, B.; Park, H.-S.; Remington, B. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Ma, T. [Center for Energy Research, University of California, San Diego, California 92093-0411 (United States); Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

2010-08-15

42

A K-alpha x-ray source using high energy and high repetition rate laser system for phase contrast imaging  

PubMed Central

K-alpha x-ray sources from laser produced plasmas provide completely new possibilities for x-ray phase-contrast imaging applications. By tightly focusing intense femtosecond laser pulses onto a solid target K-alpha x-ray pulses are generated through the interaction of energetic electrons created in the plasma with the bulk target. In this paper, we present a continuous and efficient Mo K-alpha x-ray source produced by a femtosecond laser system operating at 100 Hz repetition rate with maximum pulse energy of 110 mJ before compression. The source has an x-ray conversion efficiency of greater than 10?5 into K-alpha line emission. In preparation for phase contrast imaging applications, the size of the resultant K-alpha x-ray emission spot has been also characterized. The source exhibits sufficient spatial coherence to observe phase contrast. We observe a relatively small broadening of the K-alpha source size compared to the size of the laser beam itself. Detailed characterization of the source including the x-ray spectrum and the x-ray average yield along with phase contrast images of test objects will be presented.

Fourmaux, Sylvain; Kieffer, Jean-Claude; Kincaid, Russell; Krol, Andrzej

2009-01-01

43

Mapping of lunar volatiles with Moon Mineralogy Mapper spectra: A challenge due to thermal emission  

NASA Astrophysics Data System (ADS)

Removal of the thermal emission contribution to lunar surface reflectance spectra measurements by the Moon Mineralogy Mapper is critical for characterizing the surface composition. We use a surface roughness-based thermal emission model in order to correct M3 spectra and to monitor time of day variations of the 3-?m absorption band.

Combe, J.-Ph.; McCord, T. B.; Hayne, P. O.; Paige, D. A.

2011-10-01

44

Quantitative analysis of directional spontaneous emission spectra from light sources in photonic crystals  

SciTech Connect

We have performed angle-resolved measurements of spontaneous-emission spectra from laser dyes and quantum dots in opal and inverse opal photonic crystals. Pronounced directional dependencies of the emission spectra are observed: angular ranges of strongly reduced emission adjoin with angular ranges of enhanced emission. It appears that emission from embedded light sources is affected both by the periodicity and by the structural imperfections of the crystals: the photons are Bragg diffracted by lattice planes and scattered by unavoidable structural disorder. Using a model comprising diffuse light transport and photonic band structure, we quantitatively explain the directional emission spectra. This work provides detailed understanding of the transport of spontaneously emitted light in real photonic crystals, which is essential in the interpretation of quantum optics in photonic-band-gap crystals and for applications wherein directional emission and total emission power are controlled.

Nikolaev, Ivan S.; Lodahl, Peter; Vos, Willem L. [Complex Photonic Systems (COPS), Department of Science and Technology, and MESA Institute of Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands)

2005-05-15

45

M4,5 emission spectra from Gd2O3 and Yb2O3  

Microsoft Academic Search

The M4,5 emission spectra from Gd2O3 and Yb2O3 have been obtained in fluorescence on a double-crystal spectrometer. The profiles differ from the M4,5 emission spectra excited by electron impact. These differences are due to resonance radiation and substantiate the interpretation given by Bonnelle and Karnatak. The Malpha emission line was found to lie above (in energy) the M5-absorption resonance line

Robert E. Lavilla

1974-01-01

46

Iron K{alpha} measurement of LHD plasmas using a wide band and compact x-ray crystal spectrometer  

SciTech Connect

X-ray spectra of Fe K{alpha} transitions have been obtained on the Large Helical Device (LHD) using a wide band and compact x-ray spectrometer. The spectrometer consists of a Johann-type LiF(220) crystal with a curvature of 430 mm and a back-illuminated charge-coupled device (CCD) detector with a size of 26.6x6.7 mm{sup 2}. A wide energy range of 6.4-7.0 keV can be observed with high brightness and high temporal resolution, which enables us the measurement of K{alpha} transitions from all charge states of Fe ions. An energy resolution of the spectrometer was 10 eV at full width at half maximum. Time-developed K{alpha} spectra after injection of Fe-coated impurity pellet were also measured with a time interval of 10 ms in the full binning mode of CCD in order to analyze the impurity transport at the central column of LHD plasmas. The system can be modified to have better time response up to 1 ms to analyze the ionization and recombination processes after the pellet injection.

Sakurai, I.; Tawara, Y.; Matsumoto, C.; Furuzawa, A.; Morita, S.; Goto, M. [EcoTopia Science Institute, Nagoya University, Nagoya 464-8603, Aichi (Japan); National Institute for Fusion Science, Toki 509-5292, Gifu (Japan)

2006-10-15

47

On the interpretation of tungsten emission spectra in fusion devices  

NASA Astrophysics Data System (ADS)

Atomic spectra emitted by fusion plasmas are generally contaminated by ions originating from plasma erosion of material walls. These ions may be present in several charge states and the radiation they emit falls in the x-ray to vacuum ultraviolet regions, making them atomic fingerprints used as a diagnostic tool. This work reports on recent achievements on the interpretation of specific tungsten spectra from the Axially Symmetric Divertor Experiment (ASDEX) Upgrade tokamak and the Large Helical Device (LHD) stellarator.

Madeira, T. I.; Amorim, P.; Parente, F.; Indelicato, P.; Marques, J. P.

2013-09-01

48

Infrared spectra of carbon stars with silicate-like emission  

Microsoft Academic Search

Near-infrared photometry was carried out for 15 carbon stars, including three peculiar carbon stars (BM Gem, V778 Cyg, and EU And) which have a 10-micron emission feature similar to the silicate emission characteristic of oxygen-rich stars. It was found that these carbon stars with silicatelike emission have excesses at both the 12- and 25-micron bands regarding IRAS photometric data which

Kunio Noguchi; Hiroshi Murakami; Hiroshi Matsuo; Manabu Noda; Hiroyuki Hamada; Toyoki Watabe

1990-01-01

49

Equilibrium excited state and emission spectra of molecular aggregates from the hierarchical equations of motion approach.  

PubMed

The hierarchical equations of motion (HEOM) method was applied to calculate the emission spectra of molecular aggregates using the Frenkel exciton model. HEOM equations for the one-exciton excited state were first propagated until equilibration. The reduced density operator and auxiliary density operators (ADOs) were used to characterize the coupled system-bath equilibrium. The dipole-dipole correlation functions were then calculated to obtain the emission spectra of model dimers, and the B850 band of light-harvesting complex II (LH2) in purple bacteria. The effect of static disorder on equilibrium excited state and the emission spectra of LH2 was also explicitly considered. Several approximation schemes, including the high temperature approximation (HTA) of the HEOM, a modified version of the HTA, the stochastic Liouville equation approach, the perturbative time-local and time-nonlocal generalized quantum master equations, were assessed in the calculation of the equilibrium excited state and emission spectra. PMID:23387623

Jing, Yuanyuan; Chen, Liping; Bai, Shuming; Shi, Qiang

2013-01-28

50

Chemometric analysis of infrared emission spectra for quantitative analysis of BPSG films on silicon.  

National Technical Information Service (NTIS)

Infrared emission spectra of 21 borophosphosilicate glass (BPSG) thin films on silicon wafers were collected with the samples held at constant temperature between 125--400(degree)C using a heating stage designed for precise temperature control ((plus minu...

J. E. Franke C. S. Chen S. Zhang T. M. Niemczyk D. M. Haaland

1993-01-01

51

Multiple excitation wavelength fluorescence emission spectra technique for discrimination of phytoplankton  

Microsoft Academic Search

In vivo fluorescence methods are efficient tools for studying the distribution of phytoplankton in nature. Different algae species\\u000a usually have different pigments with different ratios, which results in different fluorescence emission spectra. Based on\\u000a multiple excitation wavelength fluorescence emission spectra, a discrimination technique is established in this study. The\\u000a discrimination method, established by multivariate linear regression and weighted least-squares, was

Xupeng Hu; Rongguo Su; Fang Zhang; Xiulin Wang; Hongtao Wang; Zhixi Zheng

2010-01-01

52

Infrared Spectra and Circumstellar Emission of Late-Type Stars. III. S-Type Stars  

Microsoft Academic Search

Near-infrared photometry was carried out at the J, H, K, and L bands for 73 S-type stars. The statistical characteristics of the infrared spectra and the circumstellar emission of S-type stars were examined using near-infrared photometric data, IRAS photometric data, and the low-resolution spectra obtained by IRAS. The characteristics of the photometric spectra of S-type stars were compared with those

Kunio Noguchi; Jinghao Sun; Gang Wang

1991-01-01

53

Evaluation of land surface reflectance and emissivity spectra retrieved from MASTER data  

NASA Astrophysics Data System (ADS)

The MODIS/ASTER (MASTER) airborne simulator which has fifty bands in the visible to the thermal-infrared spectral regions was developed mainly to support the Advanced Spaceborne Thermal Emission and Reflection radiometer (ASTER) and the Moderate resolution Imaging Spectroradiometer (MODIS) instrument teams in the areas of algorithm development, calibration and validation, but its wide spectral capability is also useful for other studies such as geology, environmental monitoring, and land management. Currently, only MASTER product distributed to users is a level-1B at-sensor radiance product, so that if a user needs surface reflectance and/or emissivity/temperature, the user should apply atmospheric correction to a level-1B product. Thus in the present study, we derived surface reflectance and emissivity spectra from MASTER data acquired over Railroad Valley Playa, NV/USA, by atmospheric correction with various atmospheric sources like Aerosol Robotic Network (AERONET) products, and then compared with in-situ measured spectra for both reflective and emissive regions. Calibration errors in the reflective region which caused discrepancy from the in-situ spectra were reduced by adjusting the MASTER radiance to ASTER and MODIS radiances at the top of the atmosphere. We also compared the spectral similarity in the reflective region versus that in the emissive region, for MASTER spectra, and the spectra of ASTER spectral library and in-situ spectra, as an example of discrimination analysis using both reflective and emissive bands.

Sugisaki, Takashi; Tonooka, Hideyuki

2008-10-01

54

Imaging Emission Spectra with Handheld and Cellphone Cameras  

ERIC Educational Resources Information Center

|As point-and-shoot digital camera technology advances it is becoming easier to image spectra in a laboratory setting on a shoestring budget and get immediate results. With this in mind, I wanted to test three cameras to see how their results would differ. Two undergraduate physics students and I used one handheld 7.1 megapixel (MP) digital Cannon

Sitar, David

2012-01-01

55

Imaging Emission Spectra with Handheld and Cellphone Cameras  

ERIC Educational Resources Information Center

As point-and-shoot digital camera technology advances it is becoming easier to image spectra in a laboratory setting on a shoestring budget and get immediate results. With this in mind, I wanted to test three cameras to see how their results would differ. Two undergraduate physics students and I used one handheld 7.1 megapixel (MP) digital Cannon

Sitar, David

2012-01-01

56

Phase-contrast x-ray imaging with intense Ar K{alpha} radiation from femtosecond-laser-driven gas target  

SciTech Connect

Intense Ar K{alpha} x ray with very little continuum background has been generated using a dense Ar gas irradiated with an intense femtosecond laser, with the measured flux of 1.2x10{sup 3} photons/mrad{sup 2}/pulse. This compact quasimonochromatic x-ray source, with a source size of only 12 {mu}m, has been applied to x-ray radiographic imaging of a biological specimen, resulting in high-resolution, high quality phase-contrast images. Correlation between this intense K{alpha} emission with the laser channeling in the Ar gas is discussed.

Chen, L. M.; Kando, M.; Ma, J.; Kotaki, H.; Fukuda, Y.; Hayashi, Y.; Daito, I.; Homma, T.; Ogura, K.; Mori, M.; Pirozhkov, A. S.; Koga, J.; Daido, H.; Bulanov, S. V.; Kimura, T.; Tajima, T.; Kato, Y. [Advanced Photon Research Center, Japan Atomic Energy Agency, 8-1 Umemidai Kizugawa, Kyoto 619-0215 (Japan)

2007-05-21

57

Autofluorescence emission spectra of neuronal lipopigment in animal and human ceroidoses (ceroid-lipofuscinoses)  

Microsoft Academic Search

A method for the measurement of autofluorescence emission spectra of intraneuronal lipopigment in tissue sections has been applied to specimens from dogs and sheep with forms of neuronal ceroid-lipofuscinosis (NCL). The characteristics of an emission spectrum probably reflect the composition of the lipopigment, and the results are compared with those previously reported from human NCLs and lipofuscin in non-diseased elderly

J. H. Dowson; D. Armstrong; N. Koppang; B. D. Lake; R. D. Jolly

1982-01-01

58

Imaging Emission Spectra with Handheld and Cellphone Cameras  

NASA Astrophysics Data System (ADS)

As point-and-shoot digital camera technology advances it is becoming easier to image spectra in a laboralory setting on a shoestring budget and get immediale results. With this in mind, I wanted to test three cameras to see how their results would differ. Two undergraduate physics students and I used one handheld 7.1 megapixel (MP) digital Cannon point-and-shoot auto focusing camera and two different cellphone cameras: one at 6.1 MP and the other at 5.1 MP.

Sitar, David

2012-12-01

59

Investigation of bound-free emission spectra of sodium-potassium  

NASA Astrophysics Data System (ADS)

This work determines relative transition dipole moment functions by fitting experimental bound-free and bound-bound emission spectra. Specifically, we use emission spectra from the 43Sigma+ ? a3Sigma+ electronic transition in the sodium-potassium, NaK, molecule. The calculations are performed using a modified version of the BCONT computer program developed by R. J. Le Roy. We examined bound-free and bound-bound emission spectra from several ro-vibrational levels of the 43Sigma+ state of NaK to the repulsive a3Sigma+ state. We considered both previously available spectra from low-lying levels and new spectra from high-lying levels. By making a slight adjustment to the inner, repulsive wall of the 43Sigma + state, we were able to improve the alignment of the peaks of the calculated spectra with those of the experimental data. Using the Inverse Perturbation Approximation (IPA) method, we determined an improved 4 3Sigma+ potential energy curve. Using this new curve, including the emission from both low-lying and high-lying 43Sigma + levels to the a3Sigma+ state, and extending our calculations to treat both bound-free and bound-bound transitions to the a3Sigma + state, we were able to determine an improved fit to the 4 3Sigma+ ? a3Sigma + transition dipole moment function that agrees very well with recent theoretical calculations.

McGeehan, Brett

60

On the Autoionization Emission for X-Ray Excited Auger Spectra  

NASA Astrophysics Data System (ADS)

Autoionization electron emission spectra coexisting with the M2,3-VV Auger line by X-ray excitation are discussed theoretically. The present study is motivated by an experiment of Brener et al. (Phys. Rev. B37 (1987) 1387) on metallic Ti, V and Cr by the use of X-rays of TiK?(4.511 keV) and AlK?(1.487 keV), where autoionization electron emission spectra coexisting with the M2,3-VV line are possible only when the X-rays are TiK?. By a model in which autoionization electron emission spectra are generated by the scattering of X-rays, while M2,3-VV spectra are generated by a resonant electron emission following the X-ray absorption, the increase of autoionization emission relative to M2,3-VV spectra with increasing energies of the incident X-rays is obtained for metallic Ti, in agreement qualitatively with the corresponding experimental result of Brener et al.

Ohmura, Yoshihiro; Sato, Toshihiro

1990-02-01

61

Structural and time resolved emission spectra of Er3+: Silver lead borate glass  

NASA Astrophysics Data System (ADS)

The structural properties of Er3+: silver lead borate glass is assessed by means of SEM, X-ray mapping, EDS and Raman analysis. In order to verify the time dependency of emission spectra, steady-state luminescence spectroscopy (SSLS) and time-resolved emission spectroscopy (TRES) studies have been performed. The stimulated emission cross-sections for the NIR emission transition 4I13/2 ? 4I15/2 (1535 nm) at 970 nm excitation are reported. The decay times were obtained by fitting one (?m = 0.301 ms) and two (?m1 = 0.141 ms, ?m2 = 0.368 ms) distributions for the NIR transition. Furthermore, by making use of TRES measurements the decay associated spectra were obtained allowing the time dependency for the different emission bands to be elucidated.

Coelho, Joo; Hungerford, Graham; Hussain, N. Sooraj

2011-08-01

62

Shaping Emission Spectra of Fluorescent Molecules with Single Plasmonic Nanoresonators  

NASA Astrophysics Data System (ADS)

We show that plasmonic nanoresonators composed of two gold nanoparticles change not only the intensity but also the spectral shape of the emission of fluorescent molecules. The plasmonic resonance frequency can be tuned by varying the distance between the nanoparticles, which allows us to selectively favor transitions of a fluorescent molecule to a specific vibrational ground state. Experimental data from correlated scattering and fluorescence microscopy agree well with calculations in the framework of generalized Mie theory. Our results show that the widely used description of a dye molecule near a metal surface as a mere two-level system is inadequate.

Ringler, M.; Schwemer, A.; Wunderlich, M.; Nichtl, A.; Krzinger, K.; Klar, T. A.; Feldmann, J.

2008-05-01

63

Spectra of the X-ray Emission from the Heliospheric Gas  

NASA Astrophysics Data System (ADS)

Spectra of the heliospheric EUV and X-ray emission induced in the charge-transfer collisions of the highly charged solar wind ions with the interstellar gas have been calculated. Cascading photon spectra of individual Oq+, Cq+, Nq+, and Neq+ ions have been constructed using recent data on ion radiative transition probabilities and the state selective population cross sections for charge-transfer collisions of the most abundant heavy solar wind ions with H and He atoms. Emission spectra have been calculated for slow and fast solar winds interacting with the heliospheric H and He gas. Relative intensities of the brightest lines have been predicted. The volume power distribution of the charge-transfer EUV and X-ray emission has been computed for simplified models of the solar winds and the interstellar gas. X-ray images of the heliosphere have been composed for the region of the heliosphere inside 10 AU from the Sun.

Kharchenko, V.; Dalgarno, A.; Repino, R.; Lallement, R.

2004-12-01

64

Radio-emission spectra of five pulsars in the 17--1420 MHz range  

SciTech Connect

Results are presented on measurements of the spectra of five pulsars in the 17--1420 MHz range at observatories at Grakovo, Pushchino, and Jodrel Bank. A ''turnover'' in the spectra at low frequencies is revealed for all five pulsars. It is concluded that a characteristic feature of pulsars is the existence of a maximum in the emission intensity lying at a frequency of 120 +- 60 MHz on the average.

Bruk, Y.M.; Davies, J.G.; Kuz'min, A.D.; Lyne, A.G.; Malofeev, V.M.; Rowson, B.; Ustimenko, B.Y.; Shitov, Y.P.

1978-09-01

65

First-principles Calculation of Resonant X-ray Emission Spectra Applied to ZnO  

SciTech Connect

A framework for calculating the k-conserving component of K edge resonant x-ray emission spectroscopy measurements of anisotropic solids is presented. The crystalline band structure is calculated using a quasiparticle self-consistent GW implementation. Coherent spectra are calculated in the Kramers-Heisenberg formalism, and the effect of the experimental geometry in the dipole approximation is fully considered. Coherent spectra are calculated for ZnO and successfully compared to previously measured data.

A Preston; A DeMasi; L Piper; K Smith; W Lambrecht; A Boonchun; T Cheiwchanchamnangij; J Arnemann; V van Schlifgaarde; B Ruck

2011-12-31

66

Soft-x-ray-emission spectra of solid Kr and Xe  

Microsoft Academic Search

We present the first soft x-ray-emission spectra for solid Kr (4{ital p}-3{ital d}) and Xe (5{ital p}-4{ital d}) that are free of complicating satellite spectra. Monochromatic synchrotron-radiation excitation is used to suppress the satellites. The data are analyzed to determine the {ital P} bandwidth for both elements; these results are compared with both photoemission data and available theoretical calculations. Bandwidths

J. J. Jia; W. L. OBrien; T. A. Callcott; Q. Y. Dong; J. E. Rubensson; D. R. Mueller; D. L. Ederer

1991-01-01

67

Soft-x-ray-emission spectra of solid Kr and Xe  

Microsoft Academic Search

We present the first soft x-ray-emission spectra for solid Kr (4p-3d) and Xe (5p-4d) that are free of complicating satellite spectra. Monochromatic synchrotron-radiation excitation is used to suppress the satellites. The data are analyzed to determine the P3\\/2 bandwidth for both elements; these results are compared with both photoemission data and available theoretical calculations. Bandwidths are found to be larger

J. J. Jia; W. L. O'brien; T. A. Callcott; Q. Y. Dong; J.-E. Rubensson; D. R. Mueller; D. L. Ederer

1991-01-01

68

Chemometric analysis of infrared emission spectra for quantitative analysis of BPSG films on silicon  

Microsoft Academic Search

Infrared emission spectra of 21 borophosphosilicate glass (BPSG) thin films on silicon wafers were collected with the samples held at constant temperature between 125--400°C using a heating stage designed for precise temperature control (±°C). Partial test squares calibrations applied to the BPSG infrared emittance spectra allowed four BPSG thin-film properties to be simultaneously quantified with precisions of 0.1 wt. %

J. E. Franke; Chuenyuan S. Chen; Songbaio Zhang; T. M. Niemczyk; D. M. Haaland

1993-01-01

69

K ? X-Ray Emission Spectra of Phosphorus Oxo Acids and Anions  

NASA Astrophysics Data System (ADS)

With a high-resolution two-crystal vacuum spectrometer, the phosphorus K? emission spectra in fluorescence are measured for H3PO3 (= H2PHO3), H3PO4, Li3PO4, Na3PO412H2O, Na2HPO4, NaH2PO4, K3PO4nH2O, K2HPO4, KH2PO4, Ca3(PO4)2, CaHPO42H2O, Ca(H2PO4)2H2O, CaHPO3H2O, Ca(H2PO2)2 and NH4H2PO4. In the phosphate compounds, a weak peak is observed on the high-energy side of the main peak K?1 and related to a molecular orbital of t2 symmetry in the PO43- ion. It is shown that the phosphorus K? emission spectra are influenced by ligand substitution and cations. The measured K? emission spectra of Li3PO4, Na3PO412H2O, K3PO4nH2O and Ca3(PO4)2 are presented along with the previously reported P-K absorption spectra of these phosphate compounds. The emission and absorption spectra are interpreted in terms of available molecular orbitals of the PO43- ion.

Sugiura, Chikara

1995-03-01

70

a Fast NIR Emission Spectrometer for Examining Explosive Events: Emission Spectra of Petn Explosions Containing Silver and Aluminum  

NASA Astrophysics Data System (ADS)

A fast Near-Infrared (NIR) spectrometer was constructed to make temporally and spectrally resolved emission measurements during post-detonation combustion of pure pentaerythritol tetranitrate (PETN) charges and PETN charges doped with 10% (by mass) Ag and Al microparticles. The post-detonation spectra are observed between 750 nm and 1500 nm at rates up to 46,992-spectra/sec, and key features are identified. Immediately following break-out of the detonation, all measured spectra are highly structured due to atomic and molecular emission. This emission decays within the first 40 ?s following break-out and is found to have lifetimes similar to that of emission from various species collected in the visible (390-600 nm) by a time-resolved streak spectrometer. For the particle-doped charges, broadband NIR emission signals can be used to determine time-resolved gray-body temperatures of the particles. At early time (0-40 ?s after breakout) gray-body temperatures in the range of 3000 to 4500 K are measured, between 60 ?s and 350 ?s after breakout the particle temperature is found to cool significantly to the range of 1200 K to 1800 K. Complementary two-color pyrometry (800 and 1150 nm) temperature measurements are found to be in fair agreement with early time data (0-25 ?s).

Piecuch, S. R.; Koch, J. D.; Lightstone, J. M.; Carney, J. R.

2009-12-01

71

Theory of autoionization emission for X-ray excited Auger spectra  

NASA Astrophysics Data System (ADS)

Variation with X-ray excitation energies of spectral shapes and intensities of autoionization electron emission coexisting with the M2,3-VV Auger line is discussed theoretically. Autoionization spectra are obtained as a one-step process of X-ray scattering, while M2,3-VV spectra are obtained as a two-step process of a resonant electron emission following the X-ray absorption. The present theoretical result agrees qualitatively with the experimental result of Brener et al. [Phys. Rev. B37, 1387 (1987)].

Ohmura, Yoshihiro; Sato, Toshihiro

1990-01-01

72

Spectra of the Heliospheric X-ray and EUV Emission Induced by Charge Transfer Collisions  

NASA Astrophysics Data System (ADS)

Spectra of the heliospheric X-ray and extreme ultraviolet (EUV) emission induced by highly charged solar wind ions are investigated. Intensities of various ion emission lines are calculated taking into account selective populations of the excited states of heavy solar wind ions in charge transfer collisions with hydrogen and helium atoms of the neutral interstellar gas. Photon cascading spectra of excited solar wind ions are computed for different compositions of the solar wind. The brightest spectral lines of the X-ray and EUV heliospheric emission are predicted for the fast and slow components of the solar wind. Polarization of these lines is analyzed. The contribution of the solar wind ion emission to the observed soft X-ray background is discussed. The time variability and the anisotropy of the heliospheric X-ray and EUV radiation are investigated.

Kharchenko, V.; Rigazio, M.; Dalgarno, A.

2001-12-01

73

Detection of H2 Emission from Mira B in Ultraviolet Spectra from the Hubble Space Telescope  

Microsoft Academic Search

We present ultraviolet spectra of Mira's companion star from the Space Telescope Imaging Spectrograph (STIS) instrument on board the Hubble Space Telescope (HST). The companion is generally assumed to be a white dwarf surrounded by an accretion disk fed by Mira's wind, which dominates the UV emission from the system. The STIS UV spectrum is dominated by numerous, narrow H2

Brian E. Wood; Margarita Karovska; Warren Hack

2001-01-01

74

On modulation lanes in spectra of Jovian decametric radio emission: low magnetosphere  

NASA Astrophysics Data System (ADS)

Modulation lanes in spectra of Jovian decametric radio emission are formed by radiation scattering on field-aligned inhomogeneities in the magnetosphere of the planet. Numeral algorithm for localization of magnetospheric inhomogeneities by the frequency drift of modulation lanes is used for the study of Jovian inner magnetosphere.

Arkhipov, A. V.

2004-09-01

75

A Safe and Interactive Method of Illuminating Discharge Tubes for Studying Emission Spectra  

ERIC Educational Resources Information Center

|Discharge tubes are useful tools for teaching emission spectra and the discrete energy levels of the Bohr model. A new setup uses a plasma globe to illuminate the discharge tube and allows a higher degree of interactivity owing to the omission of a traditional, high-voltage power source. The decreased power consumption also reduces the heating of

Lu, Zhe

2012-01-01

76

Emission spectra of Cs-He excimers in cold helium gas  

NASA Astrophysics Data System (ADS)

We observed broadband emission spectra of Cs-He excimers (Cs*He) in cold He gas (1.3-100 K), when Cs atoms were excited to the 6 2P states. We calculated the emission spectrum from each vibrational state of Cs*He using Pascale's semiempirical Cs-He potential energy curves [J. Pascale, Phys. Rev. A 28, 632 (1983)], and compared the results with the observed spectra. From the measured spectral shape, we estimated the relative populations of the vibrational states of Cs*He at various He gas densities, and estimated the predissociation rate of Cs*He in the A 2?1/2 state. Moreover, a broadband emission spectrum of Cs*He2 was also observed, which was compared with that observed in liquid He.

Enomoto, K.; Hirano, K.; Kumakura, M.; Takahashi, Y.; Yabuzaki, T.

2002-10-01

77

Influence of Clouds on the Emission Spectra of Earth-like Extrasolar Planets  

NASA Astrophysics Data System (ADS)

The climate of Earth-like planets results from the energy balance between absorbed starlight and radiative losses of heat from the surface and atmosphere to space. Clouds reflect sunlight back towards space, reducing the stellar energy available for heating the atmosphere (albedo effect), but also reduce radiative losses to space (greenhouse effect). Clouds also have a large effect on the emission spectra of planetary atmospheres, by either concealing the thermal emission from the surface or dampening the spectral features of molecules, which is, of course, also true for biomarkers (e.g., N2O and O3). We present first results on the impact of multi-layered clouds in the atmospheres of Earth-like extrasolar planets orbiting different types of central stars on the planetary IR emission spectra.

Kitzmann, D.; Patzer, A. B. C.; von Paris, P.; Godolt, M.; Grenfell, J. L.; Rauer, H.

2010-10-01

78

Reflection and thermal emission spectra of Earth-like extrasolar planets affected by clouds  

NASA Astrophysics Data System (ADS)

Clouds can have an important impact on the radiative transfer in planetary atmospheres by absorption and scattering of the incident stellar radiation and the thermal radiation from the surface. Consequently, the planetary emission and reflection spectra are strongly affected by the presence of clouds, resulting in e.g. the concealing of thermal surface emissions or dampening of molecular absorption bands in the infrared. To study these effects, a parametrised cloud description, accounting for two different types of clouds (low-level water and high-level ice clouds) and their partial overlap has been developed. The multi-layered cloud model is based on observations in the Earth's atmosphere and has been coupled with a one-dimensional radiative-convective steady state climate model to obtain low-resolution spectra of Earth-like extrasolar planets. In this contribution the impact of multi-layered on low-resolution thermal emission and reflec-tion spectra is presented for Earth-like planets orbiting different types of central stars, with special emphasis on so-called biomarker signatures. The influence of clouds on the ability to derive information about the planetary surface temperatures from low-resolution spectra is also discussed.

Kitzmann, Daniel; Patzer, A. B. C.; von Paris, Philip; Rauer, Heike

79

Breakdown of the quasistatic approximation at high densities and its effect on the heliumlike K{alpha} complex of nickel, iron, and calcium  

SciTech Connect

Recent work to include R-matrix data within a larger model comprised mostly of distorted-wave and plane-wave Born data has resulted in the general spectral modeling (GSM) code. It employs a quasistatic approximation, a standard, low-density methodology that assumes the ionization balance is separable from a determination of the excited-state populations that give rise to the spectra. GSM further allows for some states to be treated statistically as contributions to effective rates, instead of being included explicitly in the kinetics model. While these two approximations are known to be valid at low densities, this work investigates using such methods to model high-density, non-LTE emission spectra and determines at what point the approximations break down by comparing to spectra produced by the Los Alamos National Laboratory code ATOMIC which makes no such approximations. As both approximations are used by other astrophysical and low-density modeling codes, the results should be of broad interest. He-like K{alpha} emission spectra are presented for three elements, Ni, Fe, and Ca, in order to gauge the effect of both the statistical methods and the ground-state-only, quasistatic approximation employed in GSM. This work confirms that at and above the temperature of maximum abundance of the He-like ionization stage, the range of validity for both approximations is sufficient for modeling the low- and moderate-density regimes one typically finds in astrophysical and magnetically confined fusion plasmas. However, a breakdown does occur for sufficiently high densities; we obtain quantitative limits that are significantly higher than previous works. Additionally, this work demonstrates that, while the range of validity for both approximations is sufficient to accurately predict the density-dependent quenching of the z line, the approximations begin to break down at higher densities. Thus, these approximations should be used with greater care when modeling high-density plasmas such as those found in laser-driven inertial confinement fusion and electromagnetic pinch devices.

Oelgoetz, Justin; Fontes, Christopher J.; Zhang Honglin; Pradhan, Anil K. [Applied Physics Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, Ohio 43210 (United States)

2007-12-15

80

High surface porosity as the origin of emissivity features in asteroid spectra  

NASA Astrophysics Data System (ADS)

Emission features in the mid-IR domain (7-25 ?m) are quite ubiquitous among large asteroids and therefore offer the potential to uncover their surface composition. However, when comparing these spectra with the actual laboratory spectra of both minerals and meteorites, they do not necessarily match. Here, and in a companion paper by King et al. (in preparation, 2012), we show that by modifying the sample preparation - typically by suspending meteorite and/or mineral powder (<30 ?m) in IR-transparent KBr (potassium bromide) powder - we are able to reproduce the spectral behavior of those main-belt asteroids with emissivity features. This resulting good match between KBr-diluted meteorite spectra and asteroid spectra suggests an important surface porosity (>90%) for the first millimeter for our asteroid sample. It therefore appears that mid-IR emission spectra of asteroids do not only carry information about their surface composition but they can also help us constraining their surface structure (under-dense versus compact surface structure), as suggested by Emery et al. (Emery, J.P., Cruikshank, D.P., van Cleve, J. [2006]. Icarus 182, 496-512) in the case of the Jupiter Trojans. The large surface porosity inferred from the mid-IR spectra of certain asteroids is also implied by two other independent measurements, namely their thermal inertia and their radar albedo. We further clarified how much compositional information can be retrieved from the mid-IR range by focusing our analysis on a single object, 624 Hektor. We showed that the mid-IR range provides critical constraints (i) on its origin and of that of the red Trojans that we locate in the formation regions of the comets, and (ii) on the primordial composition of the dust present in the outer region (>10 AU) of the Solar System's protoplanetary disk. Future investigations should focus on finding the mechanism responsible for creating such high surface porosity.

Vernazza, P.; Delbo, M.; King, P. L.; Izawa, M. R. M.; Olofsson, J.; Lamy, P.; Cipriani, F.; Binzel, R. P.; Marchis, F.; Mern, B.; Tamanai, A.

2012-11-01

81

Quantitative Frster resonance energy transfer efficiency measurements using simultaneous spectral unmixing of excitation and emission spectra.  

PubMed

Accurate quantification of Frster resonance energy transfer (FRET) using intensity-based methods is difficult due to the overlap of fluorophore excitation and emission spectra. Consequently, mechanisms are required to remove bleedthrough of the donor emission into the acceptor channel and direct excitation of the acceptor when aiming to excite only the donor fluorophores. Methods to circumvent donor bleedthrough using the unmixing of emission spectra have been reported, but these require additional corrections to account for direct excitation of the acceptor. Here we present an alternative method for robust quantification of FRET efficiencies based upon the simultaneous spectral unmixing of both excitation and emission spectra. This has the benefit over existing methodologies in circumventing the issue of donor bleedthrough and acceptor cross excitation without the need for additional corrections. Furthermore, we show that it is applicable with as few as two excitation wavelengths and so can be used for quantifying FRET efficiency in microscope images as easily as for data collected on a spectrofluorometer. We demonstrate the accuracy of the approach by reproducing efficiency values in well characterized FRET standards: HEK cells expressing a variety of linked cerulean and venus fluorescent proteins. Finally we describe simple ImageJ plugins that can be used to calculate and create images of FRET efficiencies from microscope images. PMID:23423332

Mustafa, Sanam; Hannagan, John; Rigby, Paul; Pfleger, Kevin; Corry, Ben

2013-02-01

82

Angular-distribution neutron-emission spectra of niobium following bombardment by fast neutrons  

SciTech Connect

Neutron-emission spectra at ten angles between 20 and 160/sup 0/ and incident neutron energies of 5.9, 7.1 and 8.4 MeV were measured relative to the neutron field emitted after spontaneous fission of /sup 252/Cf. The angular distribution of inelastically scattered neutrons appears to be essentially isotropic where it can be separated from the dominant elastic scattering peak. Above an excitation energy of 4 MeV the spectra are well described by a Maxwellian temperature distribution.

Guenther, P.T.; Smith, A.B.

1985-01-01

83

Time-resolved emission spectra and anisotropy profiles for symmetric diacyl- and dietherphosphatidylcholines  

Microsoft Academic Search

The solvent relaxation behavior of Patman (6-palmitoyl-2-[[2-(trimethylammonium) ethyl]methylamino]naphthalene chloride) was\\u000a investigated in small unilamellar vesicles composed of symmetric diacyl( 1,2-dipalmitoylphosphatidylcholine; DPPC) and diether\\u000a lipids (l,2-dihexadecylphosphatidylcholine; DHPC), calculating time-resolved emission spectra (TRES) and correlation functions.\\u000a Both the steady-state spectra as a function of temperature and excitation wavelength and the TRES of Patman in DPPC are blue-shifted\\u000a compared to those in DHPC.

R. Hutterer; F. W. Schneider; M. Hof

1997-01-01

84

Soft-x-ray-emission spectra of solid Kr and Xe  

SciTech Connect

We present the first soft x-ray-emission spectra for solid Kr (4{ital p}-3{ital d}) and Xe (5{ital p}-4{ital d}) that are free of complicating satellite spectra. Monochromatic synchrotron-radiation excitation is used to suppress the satellites. The data are analyzed to determine the {ital P}{sub 3/2} bandwidth for both elements; these results are compared with both photoemission data and available theoretical calculations. Bandwidths are found to be larger than those predicted by most electronic structure calculations.

Jia, J.J.; O'Brien, W.L.; Callcott, T.A.; Dong, Q.Y. (University of Tennessee, Knoxville, TN (USA)); Rubensson, J.; Mueller, D.R.; Ederer, D.L. (National Institute of Standards and Technology, Gaithersburg, MD (USA))

1991-08-05

85

Chemometric analysis of infrared emission spectra for quantitative analysis of BPSG films on silicon  

SciTech Connect

Infrared emission spectra of 21 borophosphosilicate glass (BPSG) thin films on silicon wafers were collected with the samples held at constant temperature between 125--400{degree}C using a heating stage designed for precise temperature control ({plus_minus}{degree}C). Partial test squares calibrations applied to the BPSG infrared emittance spectra allowed four BPSG thin-film properties to be simultaneously quantified with precisions of 0.1 wt. % for boron and phosphorus, 35 {Angstrom} for film thickness, and 1.2{degree}C for temperature.

Franke, J.E.; Chen, Chuenyuan S.; Zhang, Songbaio; Niemczyk, T.M. [New Mexico Univ., Albuquerque, NM (United States). Dept. of Chemistry; Haaland, D.M. [Sandia National Labs., Albuquerque, NM (United States)

1993-11-01

86

Optical emission spectra of ZnMnO plasma produced by a pulsed laser  

NASA Astrophysics Data System (ADS)

Optical emission lines from the plasma generated by a laser ablation process have been investigated to gather information on the nature of the chemical species present. In particular, the experiments were carried out during the laser ablation of a ZnMnO target, in presence of a controlled oxygen atmosphere. The resolved emission spectra are dominated by the atomic neutral or singly ionized emission lines from Zn species, while the Mn I line was detected in emission spectrum at 40 mTorr only. The background continuum, intensities and widths of all observed lines increased with increasing gas pressure. The electron density and electron temperature were calculated for various gas pressures. The electron density was found to increase with the increment of the argon gas pressure, whereas electron temperature decreased. The electron temperature and density are found to be similar to those obtained in the well-known pulsed laser deposition (PLD) process.

Uzuriaga, J.; Chamorro, J. C.; Marn, R. A.; Riascos, H.

2012-06-01

87

Emission Lines between 1 and 2 keV in Cometary X-Ray Spectra  

NASA Astrophysics Data System (ADS)

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

Ewing, Ian; Christian, Damian J.; Bodewits, Dennis; Dennerl, Konrad; Lisse, Carey M.; Wolk, Scott J.

2013-01-01

88

Infrared emission spectra of benzene and naphthalene - Implications for the interstellar polycyclic aromatic hydrocarbon hypothesis  

NASA Astrophysics Data System (ADS)

Results are presented of observations of emissions from the fundamental region (about 3050/cm, 3.3 microns) and first overtone (about 6000/cm, 1.7 micron) of the C-H stretching modes in C6H6 and C10H8 which were performed following UV laser excitations. Wavelength- and time-resolved emission spectra in the 3050/cm region show contributions from anharmonically shifted Delta-v = -1 transitions originating in v = 1, 2, and 3 in C6H6 and v = 1 and 2 in C10H8, as well as underlying continuum emission. The measured anharmonicities agree with literature values, and relative intensities match those predicted by theory for Delta-v = -1 transitions. The emission transition frequencies differ significantly from the corresponding absorption frequencies for both molecules, and depend on the vibrational energy of the emitter. It is concluded that unambiguous identification of the interstellar emitters cannot be established just on the basis of matching the emission frequencies to laboratory absorption spectra.

Brenner, Jerrell; Barker, John R.

1992-03-01

89

Detection of silicate emission features in the 8- to 13-micron spectra of main belt asteroids  

NASA Astrophysics Data System (ADS)

The authors present 8.0 - 13.0 micron spectra (??/? = 0.02 - 0.03) for six main belt asteroids, which range from 58 to 220 km in diameter and sample the five principal taxonomic classes (C, S, M, R and E). Narrow, well-defined silicate emission features are present on two of the asteroids, the C-type 19 Fortuna and the M-type 21 Lutetia. No comparable emission features are observed on the S-types 11 Parthenope and 14 Irene, the R-type 349 Dembowska or the E-type 64 Angelina.

Feierberg, M. A.; Witteborn, F. C.; Lebofsky, L. A.

1983-12-01

90

Low temperature emission spectra of optically nonlinear N-benzyl-2-methyl-4-nitroaniline crystal  

NASA Astrophysics Data System (ADS)

The fluorescence and phosphorescence spectra of N-benzyl-2-methyl-4-nitroaniline (BNA) orthorhombic crystal were measured between 5 and 200 K. The fluorescence spectrum of BNA in a Shpol'skii matrix of n-heptane was also recorded at 5 K. The electronic absorption spectra parameters such as singlet and triplet state energies, dipole moments and oscillator strengths were calculated by semi-empirical and TD DFT methods. The calculated energies of singlet and triplet states and electronic transitions in the BNA molecule were compared with the experimental results. The phosphorescence decay time was estimated to be 270 ms at 5 K. It is presumed that the disappearance of vibronic structure above 30 K observed in the fluorescence spectra is caused by the nitro group vibrations while the structured phosphorescence originates from the trap states. The role of molecular shape towards emission processes in BNA crystal in terms of structure-property relationship is discussed.

Piela, Katarzyna; Kozankiewicz, Boles?aw; Lipi?ski, Jzef; Magdalena Szostak, M.

2012-08-01

91

Automated diagnostics of a magnetron discharge plasma based on atomic molecular emission spectra  

NASA Astrophysics Data System (ADS)

A software-hardware complex intended for investigating spatial distributions of the plasma spectral emissivity is described. It allows us to record and identify the lines and systems of molecular bands in an automatic mode and to perform computer processing of spectra. Molecular bands of deuterium for different electronic-vibrational-rotational transitions are identified. The excitation temperatures of atomic levels, translational, rotational and vibrational temperatures are estimated for a discharge in a planar magnetron.

Gradov, V. M.; Zimin, A. M.; Krivitskiy, S. E.; Serushkin, S. V.; Troynov, V. I.

2012-12-01

92

Laboratory Studies of Atomic Ion VUV Emission Spectra of Astrophysical Interest  

Microsoft Academic Search

Laboratory studies of the emission spectra of multiply (two to five times) charged atomic ions are being carried out in the VUV wavelength region (50-300nm) motivated by the recent space missions (HST, SOHO and FUSE). The spectrogrammes are produced using vaccum spark sources and high resolution normal incidence vacuum spectrograph. The precision of Deltalambda=0.0003-0.0005nm obtained on wavelengths lead to reliable

W.-. L. Tchang Brillet; J.-F. Wyart

2000-01-01

93

Superresolution Imaging of Multiple Fluorescent Proteins with Highly Overlapping Emission Spectra in Living Cells  

Microsoft Academic Search

Localization-based superresolution optical imaging is rapidly gaining popularity, yet limited availability of genetically encoded photoactivatable fluorescent probes with distinct emission spectra impedes simultaneous visualization of multiple molecular species in living cells. We introduce PAmKate, a monomeric photoactivatable far-red fluorescent protein, which facilitates simultaneous imaging of three photoactivatable proteins in mammalian cells using fluorescence photoactivation localization microscopy (FPALM). Successful probe identification

2011-01-01

94

Temperature dependence of the emission spectra of individual self-assembled quantum dots  

Microsoft Academic Search

We have developed a quantum-mechanical theory for the interaction of light and electron-hole excitations in semiconductor quantum dots. Our theoretical analysis results in an expression for the photoluminescence intensity in the non-linear regime. The validity of the theoretical results is tested analyzing experimental data reported for the temperature dependence of the emission spectra of an individual lens-shaped In0.4Ga0.6As self-assembled quantum

A. Zora; C. Simserides; G. P. Triberis

2010-01-01

95

Infrared emission spectra: enhancement of diagnostic features by the lunar environment.  

PubMed

Information diagnostic of general rock type is available as a well-defined emission maximum (related to the Christiansen frequency), rather than as contrast-depleted minima, in the infrared spectra of particulate solids. The amount of spectral information varies directly with the sharpness of the thermal gradient at the sample surface. Lunar thermal conditions optimize this gradient, making the moon an excellent target for remote sensing. PMID:17750058

Logan, L M; Hunt, G R

1970-08-28

96

Proposal for Predictive Expressions of Emissivity Spectra for Powdery Coal Ash  

NASA Astrophysics Data System (ADS)

The calculation expressions for the emissivity spectra of powdery coal ashes have been derived by fitting the measured emissivity spectra to improve the accuracy with which the radiative heat transfer rate can be estimated with a calculation tool for pulverized coal-fired boilers. The expressions are defined in three bands. First, in band 1, which corresponds to wavelengths ranging from 2 to 4 micrometers, and in band 3, which corresponds to wavelengths ranging from 8 to 16 micrometers, the expressions are formulated into the linear function of the weight ratio of five chemical compositions, which correspond to silica, alumina, calcium oxide, ferric oxide and magnesia, and the temperature of the coal ash and the wavelengths. Second, the expression in band 2, with the wavelengths ranging from 4 to 8 micrometers, is formulated into the cubic function of the wavelength. The expression predicts the emissivity spectra of powdery coal ash, whose raw coals range from 0.6 to 2.4 (-) in a fuel ratio (=mass ratio of fixed carbon to volatile matter in coal), with 0.050 (-) to 0.170 (-) predictability. The proposed expression has widespread predictability of powdery coal ashes that range from 2 to 16 micrometers in wavelength.

Tsuda, Shinji; Okazaki, Teruyuki; Gwosdz, Alfred

97

Radiative transfer modeling of thermal infrared emissivity spectra: Applications to Martian regolith observations  

NASA Astrophysics Data System (ADS)

Proper analysis of satellite and rover thermal infrared emissivity spectra taken at nadir and off-nadir angles of emergence from planetary regolith surfaces requires use of theoretical models for interpretation of constituent grain physical properties. However, such models have remained in stasis in recent years, with nearly a ten-year gap in significant advances. To date, no radiative transfer model (semiempirical, exact, or hybrid solution) has been able to adequately predict the nadir emissivity behavior of simple mineral assemblages. Few measurements have been attempted in the laboratory or field regarding directional emissivity effects of planetary regoliths; such measurements are necessary for modeling and interpreting directional emissivity offsets that are clearly present in the Mars Global Surveyor Thermal Emission Spectrometer (MGS-TES) dataset. This investigation focuses on two major dust microphysical properties: particle size and packing fraction. Results of a theoretical model are compared to laboratory-measured thermal infrared (wavenumber = 2000-200 cm -1 ) emissivities for micron-sized quartz particles. I show that Mie theory, a widely used but poor approximation to irregular grain shape, fails to produce the single scattering properties needed to arrive at the desired laboratory emissivity values; I also illustrate shortcomings of popular dense packing correction methods. Through numerical experiments, I provide evidence that, assuming RT methods work given sufficiently well quantified inputs, assumptions about the scatterer itself constitute the most crucial aspect of modeling nadir emissivity values. I present laboratory investigations used to obtain realistic and quantifiable input parameters to the theoretical model, i.e., particle size distribution and particle shape. Nadir and directional emissivity comparison datasets obtained in the laboratory and in the field at Mars terrestrial analog sites are presented to set the stage for modeling directional emissivity. Future directions (e.g., how to incorporate nonspherical particle shapes into the model) are briefly discussed.

Pitman, Karly M.

2005-11-01

98

Variation of Spectra Luminescence Emission of Moganite under Different Stimulation Sources  

NASA Astrophysics Data System (ADS)

This work focuses on a characterization of various type of luminescence in Moganite-rich silica minerals from Mogan (Gran Canaria, Spain). The silica minerals formed by complicated hydrous processes exhibit luminescence emissions, which depend on sample temperature and type of an irradiation for excitation such as heat, laser, ion-beam, X-ray, incident electron beam and so on. Here we examined thermoluminescence (TL), ion beam luminescence (IBL), radioluminescence (RL), cathodoluminescence (CL) of moganite aliquots combined with Raman spectroscopy for clarification of relationship between lattice defects and the spectral luminescence emissions. The spatially-resolved CL spectroscopy coupled to the environmental scanning electron microscopy (ESEM-CL) displays different luminescence spectral signals between the moganite veined core (dull emission) and the rim (bright emission) together with larger porosity and additional ions in the outer part, suggesting a later alteration process with alkali, metals and volatile ions for the moganite formation. RL and IBL spectra of silica minerals in core and rim mainly show a progressive increase in intensity of RL emission band at 470-500 nm with decrease in sample temperature, which is caused by cryogenic stress on the [AlO4]0 centers. Continuous H+ ion beam implantation on samples at room temperature produces a subtle diminishing of blue emission and a quite brightening of red emission at 700 nm assigned to Fe3+ point defects. The white turbid rim with opaline SiO2 in cavities emits bright CL emission in panchromatic CL image, and has spectral emission bands at 290 nm with high intensity (100 000 a.u.) and one at 520 nm which are probably related to H2O(Si-OH) groups, H+, Na+ and metallic ions such as Fe3+, Ti4+ and Nb4+. Moganite core zones only display emission bands at 390 nm and 670 nm (8500 a.u.) attributed to [AlO4/Na+]0 centers and silanol groups, respectively.

Garcia-Guinea, J.; Bustillo, M. A.; Crespo-Feo, E.; Tormo, L.; Finch, A. A.; Hole, D. E.; Townsend, P. D.; Correcher, V.

2009-08-01

99

A Survey of the Nuclear Emission Line Spectra of Field and Cluster Disk Galaxies.  

NASA Astrophysics Data System (ADS)

Flux calibrated, digital spectra for the nuclei of approximately 300 field and cluster disk galaxies were obtained and analyzed. High signal-to-noise spectra for a sample of those galaxy nuclei were employed to determine gas metallicities and velocity dispersions and the dominant excitation mechanisms responsible for the observed nuclear emission lines. In addition, morphological classifications in the RDDO system were determined for the spiral galaxies in Balkowski's (1973) HI survey list and for the central regions of several irregular but moderately rich clusters. The analysis of those spectra shows that both shock-excitation and power-law photoionization are important energy sources for the narrow emission line regions in the nuclei of at least 20% of "normal" disk galaxies. A number of the galaxies with high signal-to-noise spectra also show weak, broad H(alpha) emission. Those nuclei appear to be the low-luminosity extension (L(,H(beta) )(TURNEQ) 10('38) - 10('40) ergs/sec) of the Seyfert galaxy class. A complementary sample of galaxies whose nuclear emission line regions are apparently photoionized by hot, young stars is also discussed. Evidence for a correlation between nuclear activity and local galaxy density is presented, with galaxies in compact groups having enhanced activity and isolated galaxies having weak and often undetected emission lines. Gas infall from galaxy-galaxy interaction is proposed as the mechanism for producing the enhanced activity in the group galaxies. By contrast, the nuclear spectra of the Virgo disk galaxies do not appear to differ significantly from the field sample. If "stripping" has produced the observed HI deficiency in Virgo disk galaxies, then that result indicates that the stripping process is more efficient for neutral gas in the disks than for the ionized gas in the galaxy nuclei. The RDDO types are used to show that the spiral galaxies in Virgo, Abell 262, Abell 1367 and Abell 2151 are "anemic" relative to the field sample galaxies. Several explanations are explored for that effect. The Abell 1367 data are examined in particular detail because of a possible north-south dichotomy in the properties of spiral galaxies in that cluster.

Stauffer, John Richard

1981-06-01

100

Secondary scintillation in CF4: emission spectra and photon yields for MSGC and GEM  

NASA Astrophysics Data System (ADS)

Secondary scintillation (defined here as photon emission originating from electron avalanches) was studied for two gaseous micropattern detectors: MSGC (MicroStrip Gas Chamber) and GEM (Gas Electron Multiplier) operated in pure CF4. For MSGC, the study was performed in the pressure range from 1 to 5 bar; for GEM all experiments were carried out at a fixed pressure of 1 bar. Charge gains from ~ 10 to ~ 150 were used in both cases. The primary ionization of the gas was produced by alpha particles from an Am-241 source. Emission spectra of the secondary scintillation were recorded in the wavelength range from 200 to 800 nm and corrected for the response of the detection system. Photon yields (number of photons generated per electron collected at MSGC or GEM) were measured for the integrated UV (200-500 nm) and visible (500-800 nm) emission bands. The obtained emission spectra and photon-per-electron ratios were compared to the corresponding data for the primary scintillation.

Morozov, A.; Margato, L. M. S.; Fraga, M. M. F. R.; Pereira, L.; Fraga, F. A. F.

2012-02-01

101

High resolution krypton M/sub 4,5/ x-ray emission spectra  

SciTech Connect

High resolution M/sub 4,5/ (3d ..-->.. 4p) x-ray emission spectra from a krypton plasma were measured using a recently developed grazing-incidence reflection-grating monochromator/spectrometer with very high flux rates at extreme ultraviolet and soft x-ray wave lengths. The nominal resolving power of the instrument, E/..delta..E, is about 300 in this energy range (approx.80 eV). Three dipole-allowed 3d ..-->.. 4p emission lines were observed at 80.98 eV, 80.35 eV and 79.73 eV. A broad peak at about 82.3 eV is tentatively assigned to transitions resulting from Kr/sup 2 +/, and effects of excitation energy on M/sub 4,5/ x-ray emission were observed. 9 refs., 3 figs., 1 tab.

Perera, R.C.C.; Hettrick, M.C.; Lindle, D.W.

1987-10-01

102

Mid-Infrared Spectra of Polycyclic Aromatic Hydrocarbon Emission in Herbig Ae/Be stars  

NASA Astrophysics Data System (ADS)

We present spectra of four Herbig Ae/Be stars obtained with the Infrared Spectrograph (IRS) on the Spitzer Space Telescope. All four of the sources show strong emission from polycyclic aromatic hydrocarbons (PAHs), with the 6.2 ?m emission feature shifted to 6.3 ?m and the strongest CC skeletal-mode feature occurring at 7.9 ?m instead of at 7.7 ?m, as is often seen. Remarkably, none of the four stars has silicate emission. The strength of the 7.9 ?m feature varies with respect to the 11.3 ?m feature among the sources, indicating that we have observed PAHs with a range of ionization fractions. The ionization fraction is higher for systems with hotter and brighter central stars. Two sources, HD 34282 and HD 169142, show emission features from aliphatic hydrocarbons at 6.85 and 7.25 ?m. The spectrum of HD 141569 shows a previously undetected emission feature at 12.4 ?m that may be related to the 12.7 ?m PAH feature. The spectrum of HD 135344, the coolest star in our sample, shows an unusual profile in the 7-9 ?m region, with the peak emission to the red of 8.0 ?m and no 8.6 ?m PAH feature.

Sloan, G. C.; Keller, L. D.; Forrest, W. J.; Leibensperger, E.; Sargent, B.; Li, A.; Najita, J.; Watson, D. M.; Brandl, B. R.; Chen, C. H.; Green, J. D.; Markwick-Kemper, F.; Herter, T. L.; D'Alessio, P.; Morris, P. W.; Barry, D. J.; Hall, P.; Myers, P. C.; Houck, J. R.

2005-10-01

103

A novel zirconium K{alpha} imager for high energy density physics research  

SciTech Connect

We report on the development and characterization of a zirconium K{alpha} imager for high energy density physics research. The imager consists of a spherically bent quartz crystal operating at 15.7 keV photon energy. We compare the performance of the imager in terms of integrated reflectivity (R{sub int}) and temperature dependent collection efficiency ({eta}{sub Te}) to that of the widely used Cu K{alpha} imager. Our collisional-radiative simulations show that the new imager can be reliably used up to 250 eV plasma temperature. Monte Carlo simulations show that for a 25 {mu}m thick tracer layer of zirconium, the contribution to K{alpha} production from photo-pumping is only 2%. We present, for the first time, 2D spatially resolved images of zirconium plasmas generated by a high intensity short pulse laser interacting with Zr solid targets.

Akli, K. U.; Jiang, S.; Storm, M. S.; Krygier, A.; Freeman, R. R. [The Ohio State University, Columbus, Ohio 43210 (United States); Sanchez del Rio, M. [European Synchrotron Radiation Facility (France); Stephens, R. B. [General Atomics, San Diego, California 92121 (United States); Pereira, N. R. [Ecopulse Inc., Springfield, Virginia 22152 (United States); Baronova, E. O. [RRC Kurchatov Institute, Moscow (Russian Federation); Theobald, W. [Laboratory for Laser Energetics, Rochester, New York 14623 (United States); Ping, Y.; McLean, H. S.; Patel, P. K.; Key, M. H. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

2011-12-15

104

Detection and Characterisation of H-{alpha} Emission Lines from Gaia BP/RP Spectra  

SciTech Connect

The Gaia probe, set to launch in 2011, will measure an estimated billion astronomical objects, producing an enormous amount of data. One of the data analysis tasks will be the identification and classification of measured objects. A vast majority of them will be 'ordinary' stars from our Galaxy but a certain percentage will belong to 'peculiar' objects. We are interested in detecting emission line stars (ELS). The characteristic feature of most ELS is the presence of a H-{alpha} emission line in their spectra. In the case of Gaia measurements, the influence of this line could be detected in low resolution prismatic spectra which will be recorded both in blue (BP) and red (RP) spectral region. In this work, we compare different algorithms for detecting and characterising H-{alpha} lines in Gaia spectra. These include a simple, integrated flux ratio-based algorithm and several machine learning algorithms, such as neural networks, support vector machines and support vector regression. We study line detection both from single-transit and over-sampled end-of-mission data.

Jaenes, Juergen [University of Tartu, Institute of Computer Science, Tartu Observatory (Estonia); Laur, Sven [University of Tartu, Institute of Computer Science (Estonia); Kolka, Indrek [Tartu Observatory (Estonia)

2008-12-05

105

The Emission-line Spectra of Major Mergers: Evidence for Shocked Outflows  

NASA Astrophysics Data System (ADS)

Using a spectral decomposition technique, we investigate the physical origin of the high-velocity emission-line gas in a sample of 39 gas-rich, ultraluminous infrared galaxy mergers. Regions with shock-like excitation were identified in two kinematically distinct regimes, characterized by broad (? > 150 km s-1) and narrow linewidths (? <= 150 km s-1). Here, we investigate the physical origin of the broad emission, which we show is predominantly excited by shocks with velocities of 200-300 km s-1. Considering the large amount of extinction in these galaxies, the blueshift of the broad emission suggests an origin on the near side of the galaxy and therefore an interpretation as a galactic outflow. The large spatial extent of the broad, shocked emission component is generally inconsistent with an origin in the narrow-line region of an active galactic nucleus. The kinetic energy in the mass loss as well as the luminosity of the emission lines is consistent with the fraction of the supernova energy attributed to these mechanisms by shocked stellar winds. Since some shocks can be recognized in moderately high resolution, integrated spectra of nearby ultraluminous starbursts, the spectral fitting technique introduced in Soto & Martin may therefore be used to improve the accuracy of the physical properties measured for high-redshift galaxies from their (observed frame) infrared spectra. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

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

2012-09-01

106

Excitation and emission spectra of rubidium in rare-gas thin-films.  

PubMed

To understand the optical properties of atoms in solid state matrices, the absorption, excitation, and emission spectra of rubidium doped thin-films of argon, krypton, and xenon were investigated in detail. A two-dimensional spectral analysis extends earlier reports on the excitation and emission properties of rubidium in rare-gas hosts. We found that the doped crystals of krypton and xenon exhibit a simple absorption-emission relation, whereas rubidium in argon showed more complicated spectral structures. Our sample preparation employed in the present work yielded different results for the Ar crystal, but our peak positions were consistent with the prediction based on the linear extrapolation of Xe and Kr data. We also observed a bleaching behavior in rubidium excitation spectra, which suggests a population transfer from one to another spectral feature due to hole-burning. The observed optical response implies that rubidium in rare-gas thin-films is detectable with extremely high sensitivity, possibly down to a single atom level, in low concentration samples. PMID:22779665

Gerhardt, Ilja; Sin, Kyungseob; Momose, Takamasa

2012-07-01

107

Stratospheric Images of Jupiter Derived from Hydrocarbon Emissions in Voyager 1 and 2 IRIS Spectra  

NASA Astrophysics Data System (ADS)

Spectroscopic data obtained by the Infrared Interferometer Spectrometer (IRIS) aboard Voyager 1 and 2 have been re-visited. Using the spectroscopic data and footprints of the IRIS aperture on the planet, we constructed images of the stratosphere of Jupiter at the emission bands of hydrocarbons including CH4, C2H6, C2H2, C3H4, C6H6, and C2H4. Thermal emission from the hydrocarbons on Jupiter originates from a broad region of the stratosphere extending from 1 to 10 millibars. We averaged the data using a bin of 20 degrees of longitude and latitudes in order to increase signal-to-noise ratios. The resultant images show interesting wave structure in Jupiter's stratosphere. Fourier transform analyses of these images yield wavenumbers 5 - 7 at mid-Northern and mid-Southern latitudes, and these results are different from those resulted from previous ground-based observations and recent Cassini CIRS, suggesting temporal variations on the stratospheric infrared pattern. The comparisons of the Voyager 1 and 2 spectra also show evidence of temporal intensity variations not only on the infrared hydrocarbon polar brightenings of hydrocarbon emissions but also on the stratospheric infrared structure in the temperate regions of Jupiter over the 4 month period between the two Voyager encounters. Short running title: Stratospheric Images of Jupiter derived from Voyager IRIS Spectra.

Seo, Haingja; Kim, Sang Joon; Choi, W. K.; Kostiuk, T.; Bjoraker, G.

2005-12-01

108

High-resolution measurements, line identification, and spectral modeling of K[alpha] transitions in Fe XVIII-XXV  

SciTech Connect

The iron K[alpha] emission spectrum covering the wavelength region from 1.840 to 1.940 [Angstrom] is analyzed. Measurements are made with a high-resolution Bragg crystal spectrometer on the Princeton Large Torus (PLT) tokamak for plasma conditions which closely resemble those of solar flares. A total of 40 features are identified consisting of either single or multiple lines from eight charge states in iron, Fe XVIII through Fe XXV, and their wavelengths are determined with an accuracy of 0.1--0.4 m[Angstrom]. Many of these features are identified for the first time. In the interpretation of our observations we rely on model calculations that determine the ionic species abundances from electron density and temperature profiles measured independently with non-spectroscopic techniques and that incorporate theoretical collisional excitation and dielectronic recombination rates resulting in the excitation of the 1s2s[sup r]2p[sup s] configurations. The model calculations also include the effect of diffusive ion transport. Good overall agreement between the model calculations and the observations is obtained, which gives us confidence in our line identifications and spectral modeling capabilities. The results are compared with earlier analyses of the K[alpha] emission from the Sun. While many similarities are found, a few differences arise from the somewhat higher electron density in tokamak plasmas (10[sup 13] cm[sup [minus]3]), which affects the fine-structure level populations of the ground states of the initial ion undergoing electron-impact excitation or dielectronic recombination. We also find that several spectral features are comprised of different transitions from those reported in earlier analyses of solar data.

Beiersdorfer, P.; Phillips, T. (Lawrence Livermore National Lab., CA (United States)); Jacobs, V.L. (Naval Research Lab., Washington, DC (United States). Condensed Matter and Radiation Sciences Div.); Hill, K.W.; Bitter, M.; von Goeler, S. (Princeton Univ., NJ (United States). Plasma Physics Lab.); Kahn, S.M. (California Univ., Berkeley, CA (United States))

1992-11-01

109

High-resolution measurements, line identification, and spectral modeling of K{alpha} transitions in Fe XVIII-XXV  

SciTech Connect

The iron K{alpha} emission spectrum covering the wavelength region from 1.840 to 1.940 {Angstrom} is analyzed. Measurements are made with a high-resolution Bragg crystal spectrometer on the Princeton Large Torus (PLT) tokamak for plasma conditions which closely resemble those of solar flares. A total of 40 features are identified consisting of either single or multiple lines from eight charge states in iron, Fe XVIII through Fe XXV, and their wavelengths are determined with an accuracy of 0.1--0.4 m{Angstrom}. Many of these features are identified for the first time. In the interpretation of our observations we rely on model calculations that determine the ionic species abundances from electron density and temperature profiles measured independently with non-spectroscopic techniques and that incorporate theoretical collisional excitation and dielectronic recombination rates resulting in the excitation of the 1s2s{sup r}2p{sup s} configurations. The model calculations also include the effect of diffusive ion transport. Good overall agreement between the model calculations and the observations is obtained, which gives us confidence in our line identifications and spectral modeling capabilities. The results are compared with earlier analyses of the K{alpha} emission from the Sun. While many similarities are found, a few differences arise from the somewhat higher electron density in tokamak plasmas (10{sup 13} cm{sup {minus}3}), which affects the fine-structure level populations of the ground states of the initial ion undergoing electron-impact excitation or dielectronic recombination. We also find that several spectral features are comprised of different transitions from those reported in earlier analyses of solar data.

Beiersdorfer, P.; Phillips, T. [Lawrence Livermore National Lab., CA (United States); Jacobs, V.L. [Naval Research Lab., Washington, DC (United States). Condensed Matter and Radiation Sciences Div.; Hill, K.W.; Bitter, M.; von Goeler, S. [Princeton Univ., NJ (United States). Plasma Physics Lab.; Kahn, S.M. [California Univ., Berkeley, CA (United States)

1992-11-01

110

Modeling the Role of Charge Exchange in X-ray Emission Spectra  

NASA Astrophysics Data System (ADS)

Most of the gas in the Universe is not in thermal equilibrium requiring some type of collisional non-equilibrium model for accurate interpretation of observations. When ions and neutrals are present, charge exchange (CX) is one process that can occur which plays a role in the ionization balance and may dominate the ion emission spectra, such as in the solar wind charge exchange (SWCX) mechanism. In the SWCX mechanism, a SW ion captures an electron from a heliospheric or atmospheric neutral atom creating a highly excited ion which subsequently emits one or more x-rays in a cascade to the ground state. To improve SWCX x-ray models, CX computations of the dominant SW ions colliding with neutral targets have been performed. Using the CX cross sections, x-ray spectra and hardness ratios have been calculated for collisions of a range of ions with H and He. The relevance of the spectra models to heliospheric and astrophysical environments will be discussed. This work was partially supported by NASA grants NNX09AC46G and NNG09WF24I. Synopsis: Charge exchange cross sections are used to produce x-ray spectra and hardness ratios for collisions including H and He as target ions.

Cumbee, Renata; Lyons, D.; Stancil, P. C.; Rakovic, M. J.; Schultz, D. R.

2013-01-01

111

Tropospheric water vapor profiles retrieved from pressure broadened emission spectra at 22 GHz under clear sky conditions  

Microsoft Academic Search

We present a characterization and first results of the optimal estimation retrieval of water vapor profiles from the surface up to 10 km from pressure broadened emission spectra. The spectra have a bandwidth of 1 GHz and are centered around 22.235 GHz. The measurements are made by a ground based heterodyne receiver equipped with a digital FFT spectrometer and calibrated

A. Haefele; N. Kmpfer

2009-01-01

112

Tropospheric Water Vapor Profiles Retrieved from Pressure-Broadened Emission Spectra at 22 GHz  

NASA Astrophysics Data System (ADS)

The authors present the analysis and the evaluation of the retrieval of tropospheric water vapor profiles from pressure-broadened emission spectra at 22 GHz measured with a ground-based microwave spectroradiometer. The spectra have a bandwidth of 1 GHz with a resolution of 20 MHz and are centered at 22.235 GHz. Because of the small bandwidth, the retrieval is insensitive to clouds and measurements are possible under almost all nonprecipitating weather conditions. The retrieved profiles are evaluated with a set of 200 coincident balloon soundings with RS92 sensors. The correlation coefficient between the microwave retrievals and the RS92 measurements lies above 0.7 km, up to 8 km, and the retrievals show a wet bias compared to RS92 of 10% at 2 km, increasing to 30% at 6 km.

Haefele, Alexander; Kmpfer, Niklaus

113

Emission spectra analysis of arc plasma for synthesis of carbon nanostructures in various magnetic conditions  

SciTech Connect

Arc discharge supported by the erosion of anode materials is one of the most practical and efficient methods to synthesize various high-quality carbon nanostructures. By introducing a non-uniform magnetic field in arc plasmas, high-purity single-walled carbon nanotubes (SWCNT) and large-scale graphene flakes can be obtained in a single step. In this paper, ultraviolet-visible emission spectra of arc in different spots under various magnetic conditions are analyzed to provide an in situ investigation for transformation processes of evaporated species and growth of carbon nanostructures in arc. Based on the arc spectra of carbon diatomic Swan bands, vibrational temperature in arc is determined. The vibrational temperature in arc center was measured around 6950 K, which is in good agreement with our simulation results. Experimental and simulation results suggest that SWCNT are formed in the arc periphery region. Transmission electronic microscope and Raman spectroscope are also employed to characterize the properties of carbon nanostructures.

Li Jian; Kundrapu, Madhusudhan; Shashurin, Alexey; Keidar, Michael [Department of Mechanical and Aerospace Engineering, George Washington University, Washington, DC 20052 (United States)

2012-07-15

114

Emission spectra analysis of arc plasma for synthesis of carbon nanostructures in various magnetic conditions  

NASA Astrophysics Data System (ADS)

Arc discharge supported by the erosion of anode materials is one of the most practical and efficient methods to synthesize various high-quality carbon nanostructures. By introducing a non-uniform magnetic field in arc plasmas, high-purity single-walled carbon nanotubes (SWCNT) and large-scale graphene flakes can be obtained in a single step. In this paper, ultraviolet-visible emission spectra of arc in different spots under various magnetic conditions are analyzed to provide an in situ investigation for transformation processes of evaporated species and growth of carbon nanostructures in arc. Based on the arc spectra of carbon diatomic Swan bands, vibrational temperature in arc is determined. The vibrational temperature in arc center was measured around 6950 K, which is in good agreement with our simulation results. Experimental and simulation results suggest that SWCNT are formed in the arc periphery region. Transmission electronic microscope and Raman spectroscope are also employed to characterize the properties of carbon nanostructures.

Li, Jian; Kundrapu, Madhusudhan; Shashurin, Alexey; Keidar, Michael

2012-07-01

115

Modelling of emission spectra of Pr I by summarizing hyperfine patterns of overlapping spectral lines  

NASA Astrophysics Data System (ADS)

We present studies of the the hyperfine (hf) structure of spectral lines of Praseodymium (Pr) by laser spectroscopic investigations as well as by analyzing Fourier Transform (FT) spectra. The experimental part of our work is done with the technique of laser-induced fluorescence (LIF) spectroscopy in a hollow cathode lamp. We present detailed studies of the very small region of 1.5 (from 5810.5 to 5812.0 ) in the visible area of the FT spectrum where at least 14 spectral lines are overlapping. In the investigated region we discovered two new even levels and three new odd levels and could classify 11 new spectral lines. The final goal is to model the emission spectrum by a sum of the hf profiles of all spectral lines in a certain region. Application of such modelling may be found in analyzing highly resolved stellar spectra.

Gamper, B.; Khan, S.; Siddiqui, I.; Windholz, L.

2013-10-01

116

[Optimization of optical parametric amplification on femtosecond fluorescence spectra by referring to cone emission].  

PubMed

Femtosecond time-resolved fluorescence spectra technique based on non-collinear optical parametric amplification is a new method for ultrafast spectroscopy research In the present report, the authors discuss the dynamic range for amplifying fluorescence. The supercontinuum seed can be amplified linearly to its transient intensity. Due to large amplification ratio up to 10(7), small instability in pump pulse energy produces large fluctuation in final output amplitude. Here the authors introduce a method using cone emission as reference to overcome this difficulty. The results show significant improvement in fluorescence dynamics curve. PMID:21800583

Li, Feng-ming; Wang, Shu-feng; Gong, Qi-huang

2011-05-01

117

Responsivity-based criterion for accurate calibration of FTIR emission spectra: theoretical development and bandwidth estimation.  

PubMed

An analytical expression for the variance of the radiance measured by Fourier-transform infrared (FTIR) emission spectrometers exists only in the limit of low noise. Outside this limit, the variance needs to be calculated numerically. In addition, a criterion for low noise is needed to identify properly calibrated radiances and optimize the instrument bandwidth. In this work, the variance and the magnitude of a noise-dependent spectral bias are calculated as a function of the system responsivity (r) and the noise level in its estimate (?r). The criterion ?r/r<0.3, applied to downwelling and upwelling FTIR emission spectra, shows that the instrument bandwidth is specified properly for one instrument but needs to be restricted for another. PMID:21445184

Rowe, Penny M; Neshyba, Steven P; Walden, Von P

2011-03-14

118

Superresolution Imaging of Multiple Fluorescent Proteins with Highly Overlapping Emission Spectra in Living Cells  

PubMed Central

Localization-based superresolution optical imaging is rapidly gaining popularity, yet limited availability of genetically encoded photoactivatable fluorescent probes with distinct emission spectra impedes simultaneous visualization of multiple molecular species in living cells. We introduce PAmKate, a monomeric photoactivatable far-red fluorescent protein, which facilitates simultaneous imaging of three photoactivatable proteins in mammalian cells using fluorescence photoactivation localization microscopy (FPALM). Successful probe identification was achieved by measuring the fluorescence emission intensity in two distinct spectral channels spanning only ?100nm of the visible spectrum. Raft-, non-raft-, and cytoskeleton-associated proteins were simultaneously imaged in both live and fixed fibroblasts coexpressing Dendra2-hemagglutinin, PAmKate-transferrin receptor, and PAmCherry1-?-actin fusion constructs, revealing correlations between the membrane proteins and membrane-associated actin structures.

Gunewardene, Mudalige S.; Subach, Fedor V.; Gould, Travis J.; Penoncello, Gregory P.; Gudheti, Manasa V.; Verkhusha, Vladislav V.; Hess, Samuel T.

2011-01-01

119

Assessing phytoplankton using a two-rank database based on excitation-emission fluorescence spectra.  

PubMed

The feasibility of using a two-rank database of reference spectra based on in vivo fluorescence excitation-emission matrix (EEMs) spectra to assess dominant groups of phytoplankton was explored. Twenty-six species belonging to 20 genera of seven divisions were studied. First, fluorescent characteristics of these EEMs were extracted using Daubechies-7 wavelet analysis. Second, the optimal characteristic spectra of scale vectors (SOCS) and time-series vectors (TOCS) were selected; phytoplankton of different genera were classified using Fisher linear discriminant analysis. Third, SOCS and TOCS reference spectra databases were obtained by hierarchical cluster analysis. Using non-negative least squares as the method to assess the phytoplankton, a two-rank reference spectra database was established according to their respective ability to identify the 2818 single-species samples. Using this fluorimetric technique, the correct identification rates (CIRs) for single-species samples were 88.8-100% at the genus level and 98.8-100% at the division level. Dominant species in the 465 laboratory mixtures had corresponding CIRs of 85.6% and 96.1%. Moreover, 15 of the 19 species used as dominants were correctly identified at the genus level. In 27 natural seawater samples, Prorocentrum donghaiense, Thalassiosira nordenskioldi, and Chaetoceros socialis (bloom-forming species with a density of about 10(7) cell L(-1)), and Alexandrium sp. (dominant species with abundance of about 10(6) cell L(-1)) were qualitatively identified at the genus level; other dominant species, with densities of 10(5) to 10(6) cell L(-1), were identified at the division level. The quantitative identification was relatively poor in the natural water samples, and several potential resolutions, including trying both new measuring methods and calculating methods, for future study are given. PMID:21211146

Zhang, Fang; He, Jiangfeng; Su, Rongguo; Wang, Xiulin

2011-01-01

120

The Gas-Phase Spectra of Resonance-Stabilized Radicals and the Red Rectangle Emission  

NASA Astrophysics Data System (ADS)

Alpha aromatic radicals may explain some of the emission features of Red Rectangle (RR), a nearby protoplanetary nebulae. Erosion of amorphous hydrogenated carbon may lead to resonance-stabilized products by breaking aliphatic side-chains to aromatic ``islands''. The resulting radicals may be excited by starlight to give rise to the characteristic emissions. As a part of the ongoing Research and in order to investigate this hypothesis, the gas-phase excitation and emission spectra of some of these radicals have been identified in a molecular beam using laser induced fluorescence (LIF) spectroscopy. Resonance-stabilized 1-naphthylmethyl, 2-naphthylmethyl and acenaphthenyl radicals were produced from the discharge of 1-methylnaphthalene, 2-methylnaphthalene and acenaphthene precursors in argon, respectively. In order to determine the ground state vibrational energies of these species, their fluorescence bands were dispersed. The results are consistent with the Density Functional Theory (DFT) calculated ground state frequencies. As a complementary experiment, and to further confirm the identity of the spectral carriers, resonant two color two photon ionization (R2C2PI) spectra were also recorded. The origin bands of all these three molecules show up in the 5790 - 5840 range of the spectrum, the well-known RR emission region. N. J. Reilly, D. L. Kokkin, M. Nakajima, K. Nauta, S. H. Kable, and T. W. Schmidt J. Am. Chem. Soc., 130(10), 3137 (2009). T. P. Troy, M. Nakajima, N. Chalyavi, R. G. C. R. Clady, K. Nauta, S. H. Kable, and T. W. Schmidt J. Phys. Chem. A, 113, 10279 (2009).

Chalyavi, Nahid; Troy, Tyler P.; Nakajima, Masakazu; Nauta, Klaas; Kable, Scott H.; Schmidt, Timothy W.

2010-06-01

121

The extension of gain spectra and accurate determination of the quasi-Fermi-level separation from measured amplified spontaneous emission spectra  

NASA Astrophysics Data System (ADS)

A method for obtaining the gain spectra of semiconductor lasers in an extended energy range from amplified spontaneous emission (ASE) spectra is presented. Hakki-Paoli gain measurement is first used to determine the quasi-Fermi-level separation. By using the fitting process proposed, a self-consistent correction in determining quasi-Fermi separation leads to a reduced error (<1 meV) and a recalibration of the intrinsic absorption coefficient is also self-consistently possible. Subsequently, with measured gain in a restricted energy range, we can obtain gain spectra in a much wider energy range by our proposed algorithm in conjunction with ASE data. The application of this method in obtaining the extended gain spectra of a double-quantum-well GaInP ridge waveguide laser is demonstrated.

Fu, Liwei; Wu, Linzhang; Schweizer, Heinz

1999-11-01

122

High Energy K(alpha) Radiography Using High-intensity, Short-pulse Lasers  

SciTech Connect

We have performed experiments using Callisto, the Vulcan 100 TW and the Vulcan Petawatt high intensity lasers to understand the characteristics of high energy, K{alpha} x-ray sources and to implement workable radiography solutions at 20-100 keV. Our measurements show that the K{alpha} size from a simple foil target is larger than 60 {micro}m, far larger than the experiment resolution requirement. The total K{alpha} yield is independent of target thicknesses verifying that refluxing plays a major role in photon generation. Smaller radiating volumes emit brighter K{alpha} radiation. 1-D radiography experiments using small-edge-on foils resolved 10 {micro}m features with high contrast. We tested a variety of small volume 2-D point sources such as cones, wires, and embedded wires, measuring photon yields and comparing our measurements with predictions from hybrid-PIC LSP simulations. In addition to high-energy, high-resolution backlighters, future experiments will also need imaging detectors and diagnostic tools that are workable in the 20-100 keV energy range. An initial look at some of these detector issues is also presented.

Park, H; Izumi, N; Key, M H; King, J A; Koch, J A; Landen, O L; Patel, P K; Price, D F; Remington, B A; Robey, H F; Snavely, R A; Tabak, M; Town, R J; Wickersham, J E; Stoeckl, C; Storm, M; Theobald, W; Chambers, D M; Eagelton, R; Goldsack, T; Clarke, R J; Heathcote, R; Giraldez, E; Nikroo, A; Steinman, D A; Stephens, R B; Zhang, B B

2005-11-16

123

Dynamic charge interactions create surprising rigidity in the ER/K [alpha]-helical protein motif  

SciTech Connect

Protein {alpha}-helices are ubiquitous secondary structural elements, seldom considered to be stable without tertiary contacts. However, amino acid sequences in proteins that are based on alternating repeats of four glutamic acid (E) residues and four positively charged residues, a combination of arginine (R) and lysine (K), have been shown to form stable {alpha}-helices in a few proteins, in the absence of tertiary interactions. Here, we find that this ER/K motif is more prevalent than previously reported, being represented in proteins of diverse function from archaea to humans. By using molecular dynamics (MD) simulations, we characterize a dynamic pattern of side-chain interactions that extends along the backbone of ER/K {alpha}-helices. A simplified model predicts that side-chain interactions alone contribute substantial bending rigidity (0.5 pN/nm) to ER/K {alpha}-helices. Results of small-angle x-ray scattering (SAXS) and single-molecule optical-trap analyses are consistent with the high bending rigidity predicted by our model. Thus, the ER/K {alpha}-helix is an isolated secondary structural element that can efficiently span long distances in proteins, making it a promising tool in designing synthetic proteins. We propose that the significant rigidity of the ER/K {alpha}-helix can help regulate protein function, as a force transducer between protein subdomains.

Sivaramakrishnan, Sivaraj; Spink, Benjamin J.; Sim, Adelene Y.L.; Doniach, Sebastian; Spudich, James A. (Stanford)

2009-06-30

124

Voltage-induced evolution of emission spectra in organic light-emitting diodes  

NASA Astrophysics Data System (ADS)

A simple model for the voltage-induced alteration of emission spectra from single- as well as multilayer organic light-emitting diodes (LEDs) based on low-molecular-weight materials is reported. The relative contribution of the redshifted emission spectrum component of a dopant or a separate film in multilayer structure can be changed by electric-field-induced quenching of its excited states and/or voltage evolution of the recombination zone. The effect is demonstrated on N,N'-diamine (TPD) single-layer LEDs nonuniformly doped with a perylene bisimide pigment (PBP) and double heterostructure TPD/Alq3/PBP with 8-hydroxyquinoline aluminum, Alq3. While in the first class of LEDs the color changes from red to blue dependent on the applied voltage and average concentration of the PBP dye, the second-type structures operate in the red-green range as the blue emission from TPD is eliminated. Analytic considerations are presented relating the relative contribution of different color emission bands to the driving current and applied electric field as well as to the composition and structure parameters of LEDs such as dopant concentration or thickness of the layers.

Kalinowski, J.; di Marco, P.; Fattori, V.; Giulietti, L.; Cocchi, M.

1998-04-01

125

Dimuon transverse momentum spectra as a tool to characterize the emission region in heavy-ion collisions  

SciTech Connect

Previous dilepton measurements in heavy-ion collisions have mainly focused on invariant mass spectra to clarify in-medium changes of vector meson properties. However, a dimuon is characterized by two quantities - invariant mass M and transverse momentum p{sub T}. Like transverse momentum spectra of hadrons, p{sub T} spectra of dileptons arise from an interplay between emission temperature and collective transverse flow, whereas the invariant mass is insensitive to flow. Having two control parameters of which only one is sensitive to flow allows one at a given M to characterize the emission region in terms of average temperature and flow. Thus, one can study what phases of the fireball evolution radiate into a given mass window. We demonstrate this technique using the dimuon transverse momentum spectra measured by the NA60 Collaboration and present strong arguments that a thermalized evolution phase with T>170MeV leaves an imprint in the spectra.

Renk, Thorsten; Ruppert, Joerg [Department of Physics, Post Office Box 35, University of Jyvaeskylae, FIN-40014 (Finland) and Helsinki Institute of Physics, Post Office Box 64, University of Helsinki, FIN-00014 (Finland); Department of Physics, 3600 rue University, McGill University, Montreal, Quebec H3A 2T8 (Canada)

2008-02-15

126

Correction of emission spectra in microspectrofluorimetry using a reference lamp: computations.  

PubMed

Accurate correction of emission spectra in microspectrofluorimetry, using a reference lamp, may require that a factor for the emissivity of tungsten be introduced. This is only possible provided that the true temperature of the lamp filament is known. A method is given for obtaining the true temperature from the knowledge of the colour temperature. Also, the values of the spectral concentration of the radiance of the black body, either computed according to Planck's equation or taken from available published tables, have to be converted from energetic units to units of quanta since the photomultiplier is linear not to absorbed power but to units of quanta. When the fluorescence spectra to be corrected extend into the far red it is preferable to use a lower temperature (by lowering the supply voltage) than that for which the lamp is certified. It is possible to determine the new temperature (and then the corresponding spectral distribution) by taking a few pairs of measurements at different wavelengths both at the lower voltage and at the voltage for which the lamp is certified and then introducing these values in a non-linear regression soluble on a PC with a curve fitting program. The microscope tungsten halogen lamp can conveniently be used as a reference, thanks to its small size and its steady spectral characteristics. When high accuracy is required, however, the halogen lamp should be calibrated against a certified ribbon filament lamp. PMID:1380859

Galassi, L

1992-01-01

127

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

PubMed Central

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

2012-01-01

128

Theoretical simulations of emission spectra of Fe7+ and Fe8+  

NASA Astrophysics Data System (ADS)

The energy levels, oscillator strengths, spontaneous radiative decay rates, and electron impact collision strengths are calculated for Fe VIII and Fe IX using the recently developed flexible atomic code (FAC). These atomic data are used to analyse the emission spectra of both laboratory and astrophysical plasmas. The nf 3d emission lines have been simulated for Fe VIII and Fe IX in a wavelength range of 6 14 nm. For Fe VIII, the predicted relative intensities of lines are insensitive to temperature. For Fe IX, however, the intensity ratios are very sensitive to temperature, implying that the information of temperature in the experiment can be inferred. Detailed line analyses have also been carried out in a wavelength range of 60 80 nm for Fe VIII, where the solar ultraviolet measurements of emitted radiation spectrometer records a large number of spectra. More lines can be identified with the aid of present atomic data. A complete dataset is available electronically from http://www.astrnomy.csdb.cn/EIE/.

Zeng, Jiao-Long; Wang, Yan-Gui; Zhao, Gang; Yuan, Jian-Min

2006-07-01

129

Evaluation of potential emission spectra for the reliable classification of fluorescently coded materials  

NASA Astrophysics Data System (ADS)

The conservation and efficient use of natural and especially strategic resources like oil and water have become global issues, which increasingly initiate environmental and political activities for comprehensive recycling programs. To effectively reutilize oil-based materials necessary in many industrial fields (e.g. chemical and pharmaceutical industry, automotive, packaging), appropriate methods for a fast and highly reliable automated material identification are required. One non-contacting, color- and shape-independent new technique that eliminates the shortcomings of existing methods is to label materials like plastics with certain combinations of fluorescent markers ("optical codes", "optical fingerprints") incorporated during manufacture. Since time-resolved measurements are complex (and expensive), fluorescent markers must be designed that possess unique spectral signatures. The number of identifiable materials increases with the number of fluorescent markers that can be reliably distinguished within the limited wavelength band available. In this article we shall investigate the reliable detection and classification of fluorescent markers with specific fluorescence emission spectra. These simulated spectra are modeled based on realistic fluorescence spectra acquired from material samples using a modern VNIR spectral imaging system. In order to maximize the number of materials that can be reliably identified, we evaluate the performance of 8 classification algorithms based on different spectral similarity measures. The results help guide the design of appropriate fluorescent markers, optical sensors and the overall measurement system.

Brunner, Siegfried; Kargel, Christian

2011-05-01

130

Modeling Optically Thick Molecular Emission Spectra of Comets Using Asymmetrical Spherical Coupled Escape Probability  

NASA Astrophysics Data System (ADS)

Recent space missions (such as Deep Impact & EPOXI) have provided spectra from comets of unprecedented spatial resolution of the regions of the coma nearest the nucleus and demonstrate the need for better modeling of comae with optical depth effects included. We have developed a coma model that includes radiative transfer to model comets including optical depth effects. Coupled Escape Probability is a new exact method of radiative transfer calculations. We have adapted it for use in asymmetrical spherical situations and applied it to modeling molecular emission spectra of potentially optically thick volatiles in cometary comae. This method enables the accurate modeling of comets' spectra even in the potentially optically thick regions nearest the nucleus, such as those seen in Deep Impact observations of 9P/Tempel 1 and EPOXI observations of 103P/Hartley 2, including the observed morphological features such as asymmetries in volatile production. Here we present results of interest for three primary molecules of importance, CO, H2O and CO2 focusing on Comets Tempel 1, Hartley 2 and C2009 P1/Garradd. Although primarily motivated by the need for modeling comets, our (asymmetric spherical) radiative transfer model could be used for studying other astrophysical phenomena as well, including proto-planetary disks, planetary and exoplanetary atmospheres.

Gersch, Alan; A'Hearn, M. F.

2013-01-01

131

HD 209458b and HD 189733b Spitzer Emission Spectra Revisited  

NASA Astrophysics Data System (ADS)

In recent years, thermal emission spectra of two transiting hot Jupiter exoplanets, have been observed with the Spitzer Space telescope at wavelengths of approximately from 5 to 14?m. Lower signal to noise time-series spectra for HD189733 at wavelengths between approximately 21 and 40?m are also available. The spectra were acquired with the IRS instrument on Spitzer, at a spectral resolving power of approximately 100. We are conducting an analysis of all the Spitzer IR data for both planets, including 14 data sets that have not been previously published. Our analysis utilizes the improvement of our understanding of the instrumental effects that affect the data sets, such as using an exponential function to correct for the ramp effect. We also develop an improved treatment of the effects of the telescope's pointing drift. Our work aims to improve the current methodology of eclipse and transit spectroscopy of extrasolar planets in the thermal infrared in preparation for JWST, which will make such observations much more accessible.

Todorov, Kamen 0.; Deming, D.; Grillmair, C. J.

2013-01-01

132

Theoretically predicted soft X-ray emission and absorption spectra of fullerene-like carbon nitride (C 24N 36)  

Microsoft Academic Search

Theoretical C K and N K X-ray emission\\/absorption spectra of fullerene-like-structured carbon nitride (C24N36) clusters were obtained using discrete-variational (DV)-X? molecular orbital calculations. These calculations predicted that the energy widths of the C K and N K X-ray emission peaks would be about 8 and 6 eV, respectively; three low-energy satellites would appear in each emission spectrum; and there would

Yasuji Muramatsu; Takayoshi Hayashi; Rupert C. C. Perera

1999-01-01

133

Mineralogy of Natural Basalt Weathering Rinds With Application to Thermal Emission Spectra of Mars  

NASA Astrophysics Data System (ADS)

Mineralogy of Natural Basalt Weathering Rinds With Application to Thermal Emission Spectra of Mars M.D. Kraft, J.R. Michalski, T.G. Sharp, (and P.R. Christensen?) Chemically weathered rocks have been suggested to cover a significant portion of the Martian surface based on orbiter observations, and rocks investigated by the Mars Exploration Rover at the Gusev landing site show evidence of chemical alteration and weathering rinds. To understand remote mineralogical and chemical measurements of altered rock surfaces, whether in situ or from orbit, it is important to understand the general characteristics of weathering rinds (e.g., secondary mineralogy and microstructure in rinds) and how these characteristics affect remote observations. We are investigating a suite of weathered rocks of the Columbia River Basalt Group (CRBG) to identify chemical, mineralogical, and micro-structural changes associated with weathering and determine how these changes influence thermal emission measurements. Preliminary work shows that thermal emission spectra of weathered surfaces can vary substantially from spectra of fresh rocks despite rather low degrees of alteration in weathered surfaces. In rocks studied thus far, the predominant difference between the unweathered rock and weathering rind is an increase in porosity in the rind due to dissolution and/or volume expansion, causing a substantial increase in the volume density of micron-scale cracks. Mineralogical differences are imparted in the rind by the (partial) infilling of cracks by secondary materials that are Si, Al, and Fe-rich. A previous investigation by Colman (1982) showed that secondary silicates in basalt weathering rinds were dominantly X-ray amorphous. High-resolution secondary electron imaging of crack-filling products reveals spheroid-shaped materials, 10s of nm in diameter, which are consistent with short-range order allophane. We are currently performing additional analyses using XRD and TEM to constrain the mineralogy of secondary phases in CRGB weathering rinds, including the crystallinity of secondary silicates. Assessing chemical weathering on Mars may rely largely on the ability to detect and constrain the mineralogy of short-range order silicates, which may be the dominant Martian weathering products. Thermal emission spectroscopic data of Mars, with the detailed understanding that we intend to provide with this study, provides a unique and excellent means of constraining the nature of silicate weathering on Mars.

Kraft, M. D.; Michalski, J. R.; Sharp, T. G.; Christensen, P. R.

2004-12-01

134

BRIEF COMMUNICATION: Calculation of a magnetic field effect on emission spectra of light diatomic molecules for diagnostic application to fusion edge plasmas  

NASA Astrophysics Data System (ADS)

A scheme for computation of emission spectra of light diatomic molecules under external magnetic and electric fields is presented. As model species in fusion edge plasmas, the scheme is applied to polarization-resolved emission spectra of H2, CH, C2, BH and BeH molecules. The possibility of performing spatially resolved measurements of these spectra is examined.

Shikama, T.; Fujii, K.; Mizushiri, K.; Hasuo, M.; Kado, S.; Zushi, H.

2009-12-01

135

Emission from Hot Dust in the Infrared Spectra of Gamma-ray Bright Blazar  

NASA Astrophysics Data System (ADS)

A possible source of ?-ray photons observed from the jets of blazars is inverse Compton scattering by relativistic electrons of infrared seed photons from a hot, dusty torus in the nucleus. We use observations from the Spitzer Space Telescope to search for signatures of dust in the infrared spectra of four ?-ray bright blazars, the quasars 4C21.35, CTA102, and PKS 1510-089, and the BL Lacertae object ON231. The spectral energy distribution (SED) of the quasar 4C 21.35 contains a prominent infrared excess indicative of dust emission. After subtracting a non-thermal component with a power-law spectrum, we fit a dust model to the residual SED. The model consists of a blackbody with temperature 1200 K, plus a much weaker optically thin component at 660 K. The total luminosity of the thermal dust emission is 7.9(2)E+45 erg/s . If the dust lies in an equatorial torus, the density of IR photons from the torus is sufficient to explain the ?-ray flux from 4C21.35 as long as the scattering occurs within a few parsecs of the central engine. Upper limits to the luminosity from thermal emission from dust in CTA102, PKS 1510-089, and ON231, are 1.1E+46 , 2.3E+45 , and 6.6E+43 erg/s , respectively. The covering factor of the hot dust in 4C 21.35, 32%, is similar to non-blazar quasars, however 4C 21.35 is deficient in cooler dust. This could be the result of either ultraviolet emission from the jet heating the outer portions of the dust torus.

Malmrose, Michael; Marscher, A. P.; Jorstad, S. G.; Nikutta, R.; Elitzur, M.

2011-01-01

136

Time resolved spectra in the infrared absorption and emission from shock heated hydrocarbons  

NASA Astrophysics Data System (ADS)

We have extended the wavelength range of our previously constructed multichannel, fast recording spectrometer to the mid-infrared. With the initial configuration, using a silicon-diode (photovoltaic) array, we recorded light intensities simultaneously at 20 adjacent wavelengths, each with 20 ?s time resolution. For studies in the infrared the silicon diodes are replaced by a 20 element PbSe (photoconducting) array of similar dimensions (14 mm/element), cooled by a three-stage thermoelectric device. These elements have useful sensitivities over 1.0-6.7 ?m. Three interchangeable gratings in a 1/4 m monochromator cover the following spectral ranges: 1.0-2.5 ?m (resolution 33.6 cm-1) 2.5-4.5 ?m (16.8 cm-1) 4.0-6.5 ?m (16.7 cm-1). Incorporated in the new housing there are individually controlled bias-power sources for each detector, two stages of analogue amplification and a 20-line parallel output to the previously constructed digitizer, and record/hold computer. The immediate application of this system is the study of emission and absorption spectra of shock heated hydrocarbons-C2H2, C4H4 and C6H6-which are possible precursors of species that generate infrared emissions in the interstellar medium. It has been recently proposed that these radiations are due to PAH that emit in the infrared upon relaxation from highly excited states. However, it is possible that such emissions could be due to shock-heated low molecular-weight hydrocarbons, which are known to be present in significant abundances, ejected into the interstellar medium during stellar outer atmospheric eruptions. The full Swan band system appeared in time-integrated emission spectra from shock heated C2H2 (1% in Ar; T5eq~=2500K) no soot was generated. At low resolution the profiles on the high frequency side of the black body maximum show no distinctive features. These could be fitted to Planck curves, with temperatures that declined with time from an initial high that was intermediate between T5 (no conversion) and T5 (eq).

Bauer, S. H.; Borchardt, D. B.

1990-07-01

137

Laboratory Studies of Atomic Ion VUV Emission Spectra of Astrophysical Interest  

NASA Astrophysics Data System (ADS)

Laboratory studies of the emission spectra of multiply (two to five times) charged atomic ions are being carried out in the VUV wavelength region (50-300nm) motivated by the recent space missions (HST, SOHO and FUSE). The spectrogrammes are produced using vaccum spark sources and high resolution normal incidence vacuum spectrograph. The precision of ??=0.0003-0.0005nm obtained on wavelengths lead to reliable identification of the spectral lines and to the determination of the atomic energy levels. The atomic configurations are interpreted by parametric calculations giving rise to improved transition probabilities. Ions of the iron (Mn, Fe) and platinum groups (Au, Os) have been investigated involving international collaborations (Institute of Spectroscopy of Troitsk, University of Amsterdam, University of Lige, University of Antigonish, NIST). Future projects concern ions of rare earth elements.

Tchang Brillet, W.-. L.; Wyart, J.-F.

138

[Study of emission spectra of N atom generated in multi-needle-to-plate corona discharge].  

PubMed

The emission spectra of nitrogen (N) atom produced by multi-needle-to-plate negative corona discharge in air were detected successfully at one atmosphere, and the excited transition spectral line at 674.5 nm with maximum value of relative intensity was selected to investigate the influences of air and electrical parameters on N atom relative density. The results indicate that N atom relative density in ionization region increases with the increase in power; decreases with increasing discharge gap and relative humidity; and with the increase in N2 content, the relative density of N active atom firstly increases and then decreases. Under present experimental conditions, the maximum value of N atom relative density appears at the axial distance from needle point r = 1 mm. PMID:22870624

Ge, Hui; Yu, Ran; Zhang, Lu; Mi, Dong; Zhu, Yi-Min

2012-06-01

139

Spectra of the X-Ray Emission Induced in the Interaction between the Solar Wind and the Heliospheric Gas  

NASA Astrophysics Data System (ADS)

Spectra of the heliospheric EUV and X-ray emission induced in the charge transfer collisions of the highly charged solar wind ions with the interstellar gas have been calculated. Cascading photon spectra of individual Oq+, Cq+, Nq+, and Neq+ ions have been constructed using recent data on ion radiative transition probabilities and the state-selective population cross sections for charge transfer collisions of the most abundant heavy solar wind ions with H and He atoms. Emission spectra have been calculated for slow and fast solar winds interacting with the heliospheric H and He gas. Relative intensities of the brightest lines have been predicted. The volume power distribution of the charge transfer EUV and X-ray emission has been computed for simplified models of the solar winds and the interstellar gas. X-ray images of the heliosphere have been composed for the region inside 10 AU from the Sun.

Pepino, R.; Kharchenko, V.; Dalgarno, A.; Lallement, R.

2004-12-01

140

Neon-Like and Fluorine-Like X-Ray Emission Spectra for Elements from Cu to Sr  

Microsoft Academic Search

The L-shell soft-X-ray emission spectra of Cu, Zn, Ga, As, Br, Rb and Sr from laser-produced plasma sources were recorded with a convex-crystal spectrograph. The spectrograms were measured to provide wavelengths accurate to 2 m for neon-like and 2p5-2p43s, 3d fluorine-like transitions. Theoretical wavelengths and oscillator strengths were computed to aid the classification of the experimental spectra.

R J Hutcheon; L Cooke; M H Key; C L S Lewis; G E Bromage

1980-01-01

141

K{alpha}{sub 1} radiation from heavy, heliumlike ions produced in relativistic collisions  

SciTech Connect

Bound-state transitions in few-electron, heavy ions following radiative electron capture are studied within the framework of the density matrix theory and the multiconfiguration Dirac-Fock approach. Special attention is paid to the K{alpha}{sub 1} (1s{sub 1/2}2p{sub 3/2} {sup 1,3}P{sub J=1,2}{yields}1s{sub 1/2}{sup 2} {sup 1}S{sub J=0}) radiative decay of heliumlike uranium U{sup 90+} projectiles. This decay has recently been observed at the GSI facility in Darmstadt, giving rise to a surprisingly isotropic angular distribution, which is inconsistent with previous experiments and calculations based on a ''one-particle'' model. We show that the unexpected isotropy essentially results from the mutual cancellation of the angular distributions of the {sup 1}P{sub 1}{yields}{sup 1}S{sub 0} electric dipole and {sup 3}P{sub 2}{yields}{sup 1}S{sub 0} magnetic quadrupole transitions, both of which contribute to the K{alpha}{sub 1} radiation. Detailed computations on the anisotropy of the K{alpha}{sub 1} radiation have been carried out for a wide range of projectile energies and are compared to available experimental data.

Surzhykov, Andrey; Jentschura, Ulrich D. [Max-Planck-Institut fuer Kernphysik, D-69029 Heidelberg (Germany); Stoehlker, Thomas [Gesellschaft fuer Schwerionenforschung (GSI), D-64291 Darmstadt (Germany); Fritzsche, Stephan [Institut fuer Physik, Universitaet Kassel, D-34132 Kassel (Germany)

2006-11-15

142

Time resolved spectra in the infrared absorption and emission from shock heated hydrocarbons  

NASA Astrophysics Data System (ADS)

The wavelength range of a previously constructed multichannel fast recording spectrometer was extended to the mid-infrared. With the initial configuration, light intensities were recorded simultaneously with a silicon-diode array simultaneously at 20 adjacent wavelengths, each with a 20-micron time resolution. For studies in the infrared, the silicon diodes were replaced by a 20-element PbSe array of similar dimensions, cooled by a three-stage thermoelectric device. It is proposed that infrared emissions could be due to shock-heated low molecular-weight hydrocarbons. The full Swan band system appeared in time-integrated emission spectra from shock-heated C2H2; no soot was generated. At low resolution, the profiles on the high-frequency side of the black body maximum show no distinctive features. These could be fitted to Planck curves, with temperatures that declined with time from an initial high that was intermediate between T5 (no conversion) and T5(eq).

Bauer, S. H.; Borchardt, D. B.

143

EMISSION FROM HOT DUST IN THE INFRARED SPECTRA OF GAMMA-RAY BRIGHT BLAZARS  

SciTech Connect

A possible source of {gamma}-ray photons observed from the jets of blazars is inverse Compton scattering by relativistic electrons of infrared seed photons from a hot, dusty torus in the nucleus. We use observations from the Spitzer Space Telescope to search for signatures of such dust in the infrared spectra of four {gamma}-ray bright blazars, the quasars 4C 21.35, CTA102, and PKS 1510-089, and the BL Lacertae object ON231. The spectral energy distribution (SED) of 4C 21.35 contains a prominent infrared excess indicative of dust emission. After subtracting a non-thermal component with a power-law spectrum, we fit a dust model to the residual SED. The model consists of a blackbody with temperature {approx}1200 K, plus a much weaker optically thin component at {approx}660 K. The total luminosity of the thermal dust emission is 7.9 {+-} 0.2 x 10{sup 45} erg s{sup -1}. If the dust lies in an equatorial torus, the density of infrared photons from the torus is sufficient to explain the {gamma}-ray flux from 4C 21.35 as long as the scattering occurs within a few parsecs of the central engine. We also report a tentative detection of dust in the quasar CTA102, in which the luminosity of the infrared excess is 7 {+-} 2 x 10{sup 45} erg s{sup -1}. However, in CTA102 the far-infrared spectra are too noisy to detect the 10 {mu}m silicate feature. Upper limits to the luminosity from thermal emission from dust in PKS 1510-089, and ON231, are 2.3 x 10{sup 45}, and 6.6 x 10{sup 43} erg s{sup -1}, respectively. These upper limits do not rule out the possibility of inverse Compton upscattering of infrared photons to {gamma}-ray energies in these two sources. The estimated covering factor of the hot dust in 4C 21.35, 22%, is similar to that of non-blazar quasars; however, 4C 21.35 is deficient in cooler dust.

Malmrose, Michael P.; Marscher, Alan P.; Jorstad, Svetlana G. [Institute for Astrophysical Research, Boston University, 725 Commonwealth Avenue, Boston, MA 02215 (United States); Nikutta, Robert; Elitzur, Moshe [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506-0055 (United States)

2011-05-10

144

Emission from Hot Dust in the Infrared Spectra of Gamma-ray Bright Blazars  

NASA Astrophysics Data System (ADS)

A possible source of ?-ray photons observed from the jets of blazars is inverse Compton scattering by relativistic electrons of infrared seed photons from a hot, dusty torus in the nucleus. We use observations from the Spitzer Space Telescope to search for signatures of such dust in the infrared spectra of four ?-ray bright blazars, the quasars 4C 21.35, CTA102, and PKS 1510-089, and the BL Lacertae object ON231. The spectral energy distribution (SED) of 4C 21.35 contains a prominent infrared excess indicative of dust emission. After subtracting a non-thermal component with a power-law spectrum, we fit a dust model to the residual SED. The model consists of a blackbody with temperature ~1200 K, plus a much weaker optically thin component at ~660 K. The total luminosity of the thermal dust emission is 7.9 0.2 1045 erg s-1. If the dust lies in an equatorial torus, the density of infrared photons from the torus is sufficient to explain the ?-ray flux from 4C 21.35 as long as the scattering occurs within a few parsecs of the central engine. We also report a tentative detection of dust in the quasar CTA102, in which the luminosity of the infrared excess is 7 2 1045 erg s-1. However, in CTA102 the far-infrared spectra are too noisy to detect the 10 ?m silicate feature. Upper limits to the luminosity from thermal emission from dust in PKS 1510-089, and ON231, are 2.3 1045, and 6.6 1043 erg s-1, respectively. These upper limits do not rule out the possibility of inverse Compton upscattering of infrared photons to ?-ray energies in these two sources. The estimated covering factor of the hot dust in 4C 21.35, 22%, is similar to that of non-blazar quasars; however, 4C 21.35 is deficient in cooler dust.

Malmrose, Michael P.; Marscher, Alan P.; Jorstad, Svetlana G.; Nikutta, Robert; Elitzur, Moshe

2011-05-01

145

Spectroscopie de la Molecule CuS. Spectres d'Excitation Laser et Spectres d'Emission en Cathode Creuse (Spectroscopy of the CuS Molecule. Laser Excitation Spectra and Emission Spectra in Hollow Cathodes).  

National Technical Information Service (NTIS)

The emission spectra, green to violet, of the CuS molecule were studied using a high resolution spectroscope. Copper sulfide was chosen because it is close to the well studied CuO molecule. An experimental continuous dye laser spectroscope was used. Unkno...

F. David

1985-01-01

146

Infrared spectra and circumstellar emission of late-type stars. IV - Near-infrared spectra of S-type stars  

Microsoft Academic Search

Low-resolution near-infrared (NIR) spectra were obtained for 26 S-type stars in the wavelength region between 2 and 4 microns with a resolution of about 100. We examined the spectral characteristics of S-type stars in the infrared on the basis of both these newly obtained spectral data and previously reported photometric data. All of the stars show CO absorption at about

Kunio Noguchi; Yukiyasu Kobayashi

1993-01-01

147

Retrieval of water vapor in the upper troposphere\\/lower stratosphere from MIPAS\\/Envisat limb emission spectra  

Microsoft Academic Search

Global Measurements of water vapor in the upper troposphere and lower stratosphere (UT\\/LS) are required to assess its influence on the radiation budget of the Earth and for its use as a suitable tracer for the study of troposphere-stratosphere exchange processes (STE). MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) is a Fourier transform spectrometer measuring limb emission spectra. The field

Mathias Milz; Thomas von Clarmann; Gabriele P. Stiller; Herbert Fischer

1999-01-01

148

Extreme Ultraviolet Emission Lines of ca xv in Solar and Laboratory Spectra  

NASA Astrophysics Data System (ADS)

New R-matrix calculations of electron impact excitation rates in Caxv are used to derive theoretical electron density diagnostic emission line intensity ratios involving 2s22p2-2s2p3 transitions, specifically R1=I(208.70 )/I(200.98 ), R2=I(181.91 )/I(200.98 ), and R3=I(215.38 )/I(200.98 ), for a range of electron temperatures (Te=106.4-106.8 K) and densities (Ne=109-1013 cm-3) appropriate to solar coronal plasmas. Electron densities deduced from the observed values of R1, R2, and R3 for several solar flares, measured from spectra obtained with the Naval Research Laboratory's S082A spectrograph on board Skylab, are found to be consistent. In addition, the derived electron densities are in excellent agreement with those determined from line ratios in Caxvi, which is formed at a similar electron temperature to Caxv. These results provide some experimental verification for the accuracy of the line ratio calculations, and hence the atomic data on which they are based. A set of eight theoretical Caxv line ratios involving 2s22p2-2s2p3 transitions in the wavelength range ~140-216 are also found to be in good agreement with those measured from spectra of the TEXT tokamak plasma, for which the electron temperature and density have been independently determined. This provides additional support for the accuracy of the theoretical line ratios and atomic data.

Keenan, F. P.; Aggarwal, K. M.; Katsiyannis, A. C.; Reid, R. H. G.

2003-11-01

149

Ultrafast K-alpha Thomson scattering from shock compressed matter for use as a dense matter diagnostic  

NASA Astrophysics Data System (ADS)

Material conditions in the high-energy-density-physics regime relevant for the study of planetary formation, the modeling of planetary composition, and for inertial confinement fusion experiments, such as on the future National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory (LLNL), can be produced and studied in the laboratory using high powered lasers that shock compress material to pressures greater than > 1 Mbar. Measurement of the compression and heating of shock-compressed dense matter at high pressures is fundamental in the study and understanding of the physical and chemical properties of these extreme states. Investigation of the behavior of the ionic and elecronic properties in this regime is important to determine the equation of state and thermodynamic properties of materials under extreme conditions, that are not currently well understood. In previous work, x-ray Thomson scattering has been employed to characterize dense matter conditions, ne > 3 x 10 21cm-3, that cannot be probed using the well established technique of optical Thomson scattering. These experiments employed x-ray probes with a temporal resolution of 100 ps. However, for the full characterization of strong shocks in dense matter, an x-ray source that provides picosecond temporal resolution, i.e. K-alpha x-rays, is desirable. Presented in this thesis, are the first spectrally and temporally resolved x ray Thomson scattering measurements using ultrafast (10 ps) Ti K-alpha x-rays. These measurements have provided experimental validation for modeling of the compression and heating of shocked matter. The coalescence of two shocks launched into a solid density LiH target by a shaped 6 nanosecond heater beam was observed from rapid heating to temperatures of 2.2 eV, enabling tests of shock timing models, mainly dependent on choice of Equation of State (EOS). Here, the temperature evolution of the target at various times during shock progression was characterized from the intensity of the elastic scattering component. The observation of scattering from plasmons, electron plasma oscillations, at shock coalescence indicates a transition to a dense metallic plasma state in LiH. From the frequency shift of the measured plasmon feature the electron density was directly determined with high accuracy, providing a material compression of a factor of three times solid density. The quality of data achieved in these experiments demonstrates the capability for single-shot dynamic characterization of dense shock compressed matter. The conditions probed in this experiment are relevant for the study of the physics of planetary formation and to characterize inertial confinement fusion targets. In addition, presented in this thesis are the first ultrafast temporally, spectrally and angularly resolved x-ray Thomson scattering measurements from shock-compressed matter. These experiments allowed the testing of theoretical models used in the multi-shock experiments to infer temperatures, from dependency of the elastic scattering feature intensity on the ion form factor. The experimental spectra provided the absolute elastic and inelastic scattering intensities from the measured density of free electrons. Laser-compressed lithium-hydride samples were well characterized by inelastic Compton and Plasmon scattering of a K-alpha x-ray probe providing independent measurements of temperature and density. The data show excellent agreement with the total intensity and structure when using the two-species form factor and accounting for the screening of ion-ion interactions. Also presented in this thesis are proof-of-principle x-ray scattering measurements from inertial confinement fusion implosion targets, and a discussion of ongoing and future work. These first measurements provided temperature and density conditions for imploding CH shells for the investigation of the capsule ablator adiabat. Measurement and understanding of the adiabat response to implosion and target conditions is important and must be kept low for optimum fuel compression and tar

Kritcher, Andrea Lynn

150

Gamma-ray Spectra & Variability of Crab Nebula Emission Observed by BATSE  

NASA Astrophysics Data System (ADS)

We report 600 days of BATSE earth-occultation observations of the total gamma-ray (30 keV to 1.7 MeV) emission from the Crab Nebula, between 1991 May 24 (TJD 8400) and 1994 October 2 (TJD 9627). Lightcurves from \\{35--100, 100--200, 200--300, 300--400, 400--700, and 700--1000\\} keV, show that positive fluxes were detected by BATSE in each of these six energy bands at significances of approximately \\{ 31, 20, 9.2, 4.5, 2.6, and 1.3\\} sigma, respectively, per day. We also observed significant flux and spectral variations in the 35--300 keV energy region, with time scales of days to weeks. The spectra below 300 keV, averaged over typical CGRO viewing periods of 6--13 days, can be well described by a broken power law with average indices of 2.1 and 2.34 varying around a spectral break at 100 keV. Above 300 keV, the long-term averaged spectra, averaged over three 400 d periods (TJD 8400-8800, 8800-9200, and 9200-9600, respectively) are well represented by the same power law, extrapolated from low energies up to 670 keV, plus a hard spectral component extending from 670 keV to 1.7 MeV, with a spectral index of 1.75. The latter component could be related to a complex structure observed by COMPTEL in the 0.7-3 MeV range. Above 3 MeV, the extrapolation of the power-law continuum determined by the low-energy BATSE spectrum is consistent with fluxes measured by COMPTEL in the 3-25 MeV range, and by EGRET from 30-50 MeV. We interpret these results as synchrotron emission produced by the interaction of particles ejected from the pulsar with the field in different dynamical regions of the nebula system, as observed recently by HST, XMM-Newton, and Chandra.

Ling, J. C.; Wheaton, Wm. A.

2003-03-01

151

Development of K-alpha Absorption Diagnostics for Radiation-Driven Ablator Experiments on the OMEGA Laser  

NASA Astrophysics Data System (ADS)

We have performed a series of indirect-drive ICF experiments on the OMEGA laser as part of an ongoing effort to develop tracer spectroscopy diagnostics for hohlraum environments. The experiments we report on here involve side-by-side witness plates mounted on cylindrical hohlraums. The two witness plates differ in their dopant content and each contains different thin (<1 micron) tracers in their interiors. We use backlit absorption spectroscopy to measure the time-dependent ionization balance in the two tracer layers simultaneously. In this way, we are able to infer the time-dependent temperature in the two witness plates and thus determine how the presence of a dopant affects the Marshak wave velocity and the peak temperature achieved in the ablator sample. These experiments represent the first use of multiple tracer layers in side-by-side witness plates, and also the first use of laser-produced thorium M-shell emission to backlight potassium K-alpha absorption features.

Cohen, D. H.; Macfarlane, J. J.; Jaanimagi, P. A.; Landen, O. L.; Oertel, J. A.; Olson, R. E.; Wang, P.; Murphy, T. J.; Magelssen, G. R.; Delamater, N. D.; Leeper, R. J.

1998-11-01

152

Influence of Oil-in-Water Emulsions on Fluorescence Properties as Observed by Excitation-Emission Spectra  

NASA Astrophysics Data System (ADS)

Oil poses a major threat to marine ecosystems. This work describes a set of studies focused on introducing an efficient method for the identification of oil in the form of oil emulsions through fluorescence spectra analyses. Hence the concept of classification of oil pollution in seawater based on fluorescence spectroscopy using a high sensitive fluorimeter [1] suitable for laboratory and in situ measurements is introduced. We consider that this approach, in the future, will make it possible to collect specific fluorescence information allowing us to build a base of the oil standards. Here we examined excitation-emission fluorescence spectra (EEMs) of water containing oil-in-water emulsion prepared artificially under laboratory conditions. Water polluted with oil-in-water emulsion was studied with the objective to estimate differences in three-dimensional fluorescence spectra. Studies included various types of oils and oil concentrations. Essential differences in fluorescence spectra for various oils are indicated.

Baszanowska, E.; Zielinski, O.; Otremba, Z.; Toczek, H.

2013-10-01

153

Somatic mutations in PI3K[alpha]: Structural basis for enzyme activation and drug design  

SciTech Connect

The PI3K pathway is a communication hub coordinating critical cell functions including cell survival, cell growth, proliferation, motility and metabolism. Because PI3K{alpha} harbors recurrent somatic mutations resulting in gains of function in human cancers, it has emerged as an important drug target for many types of solid tumors. Various PI3K isoforms are also being evaluated as potential therapeutic targets for inflammation, heart disease, and hematological malignancies. Structural biology is providing insights into the flexibility of the PI3Ks, and providing basis for understanding the effects of mutations, drug resistance and specificity.

Gabelli, Sandra B.; Mandelker, Diana; Schmidt-Kittler, Oleg; Vogelstein, Bert; Amzel, L. Mario (JHU); (HHMI)

2011-09-06

154

Modeling the H? Emission Lines in Luminosity-Averaged Quasar Spectra  

NASA Astrophysics Data System (ADS)

We construct median optical spectra of quasars in bins of luminosity. The sample includes bright objects from Sloan Digital Sky Survey (with z<0.7) and sources at intermediate redshift z ? 0.9-3.0 observed with VLT ISAAC. The whole sample spans almost six decades in luminosity 43 < log[Lbol (erg s-1)] < 49. We focus our attention to objects that show FWHM (H?-broad component) = 4000 - 8000 km s-1 and RFeII = W(FeII 4434-4684)/W(H?) less than 0.5. These quasars occupy a restricted domain in the optical plane of the 4D Eigenvector 1 (4DE1) parameter space, which is luminosity independent. We model the total profile of the broad H? emission line under the assumption that it requires both a classical broad component (BC) and a redshifted very broad component (VBC). We investigate the properties of the two spectral components as a function of luminosity and report our preliminary results.

Zachary, Meadows; Zamfir, S.; Marziani, P.; Sulentic, J. W.

2011-05-01

155

High resolution study of near-infrared emission spectra of 142NdO  

NASA Astrophysics Data System (ADS)

High resolution near-infrared emission spectra of 142NdO have been recorded using a Fourier transform spectrometer. Molecules were produced by heating 142Nd2O3 to about 2100 K in a special furnace in presence of argon gas. Some 44 bands appear in the region between 7500 and 12600 cm-1, 19 of which classified into 11 systems involving 11 ? states have been analyzed in rotation. Three of these systems were known from previous studies at moderate resolution which settled the symmetry ?=4 of the ground state [L.A. Kaledin, E.A. Shenyavskaya, I. Kovacs, Acta Phys. Hung. 54 (1983) 189]. From the present analysis, information is obtained for the ground state in the levels v=0,1,2, and for the low-lying (1)5, (1)3, and (2)4 states in the levels v=0,v=0,1, and v=0, respectively; the (1)5 and (1)3 states show measurable ?-doubling. The seven upper states either are perturbed or present anomalous ?-doubling in the levels investigated; for three of them the perturbations could be reduced using a simple 22 interaction model. Their ? symmetry could be ascribed (two states with ?=3, four states with ?=4, and one state with ?=5).

Shenyavskaya, E. A.; Bernard, A.; Vergs, J.

2003-12-01

156

ANALYSIS OF OPTICAL Fe II EMISSION IN A SAMPLE OF ACTIVE GALACTIC NUCLEUS SPECTRA  

SciTech Connect

We present a study of optical Fe II emission in 302 active galactic nuclei (AGNs) selected from the Sloan Digital Sky Survey. We group the strongest Fe II multiplets into three groups according to the lower term of the transition (b{sup 4} F, a{sup 6} S, and a{sup 4} G terms). These approximately correspond to the blue, central, and red parts, respectively, of the 'iron shelf' around H{beta}. We calculate an Fe II template that takes into account transitions into these three terms and an additional group of lines, based on a reconstruction of the spectrum of I Zw 1. This Fe II template gives a more precise fit of the Fe II lines in broad-line AGNs than other templates. We extract Fe II, H{alpha}, H{beta}, [O III], and [N II] emission parameters and investigate correlations between them. We find that Fe II lines probably originate in an intermediate line region. We note that the blue, red, and central parts of the iron shelf have different relative intensities in different objects. Their ratios depend on continuum luminosity, FWHM H{beta}, the velocity shift of Fe II, and the H{alpha}/H{beta} flux ratio. We examine the dependence of the well-known anti-correlation between the equivalent widths of Fe II and [O III] on continuum luminosity. We find that there is a Baldwin effect for [O III] but an inverse Baldwin effect for the Fe II emission. The [O III]/Fe II ratio thus decreases with L {sub {lambda}5100}. Since the ratio is a major component of the Boroson and Green Eigenvector 1 (EV1), this implies a connection between the Baldwin effect and EV1 and could be connected with AGN evolution. We find that spectra are different for H{beta} FWHMs greater and less than {approx}3000 km s{sup -1}, and that there are different correlation coefficients between the parameters.

Kovacevic, Jelena; Popovic, Luka C.; Dimitrijevic, Milan S., E-mail: jkovacevic@aob.bg.ac.r [Astronomical Observatory, Volgina 7, 11060 Belgrade (Serbia)

2010-07-15

157

Simultaneous time resolution of the emission spectra of fluorescent proteins and zooxanthellar chlorophyll in reef-building corals.  

PubMed

Light is absorbed by photosynthetic algal symbionts (i.e. zooxanthellae) and by chromophoric fluorescent proteins (FP) in reef-building coral tissue. We used a streak-camera spectrograph equipped with a pulsed, blue laser diode (50 ps, 405 nm) to simultaneously resolve the fluorescence spectra and kinetics for both the FP and the zooxanthellae. Shallow water (<9 m)-dwelling Acropora spp. and Plesiastrea versipora specimens were collected from Okinawa, Japan, and Sydney, Australia, respectively. The main FP emitted light in the blue, blue-green and green emission regions with each species exhibiting distinct color morphs and spectra. All corals showed rapidly decaying species and reciprocal rises in greener emission components indicating Frster resonance energy transfer (FRET) between FP populations. The energy transfer modes were around 250 ps, and the main decay modes of the acceptor FP were typically 1900-2800 ps. All zooxanthellae emitted similar spectra and kinetics with peak emission (approximately 683 nm) mainly from photosystem II (PSII) chlorophyll (chl) a. Compared with the FP, the PSII emission exhibited similar rise times but much faster decay times, typically around 640-760 ps. The fluorescence kinetics and excitation versus emission mapping indicated that the FP emission played only a minor role, if any, in chl excitation. We thus suggest the FP could only indirectly act to absorb, screen and scatter light to protect PSII and underlying and surrounding animal tissue from excess visible and UV light. We conclude that our time-resolved spectral analysis and simulation revealed new FP emission components that would not be easily resolved at steady state because of their relatively rapid decays due to efficient FRET. We believe the methods show promise for future studies of coral bleaching and for potentially identifying FP species for use as genetic markers and FRET partners, like the related green FP from Aequorea spp. PMID:12812294

Gilmore, Adam M; Larkum, Anthony W D; Salih, Anya; Itoh, Shigeru; Shibata, Yutaka; Bena, Chiaki; Yamasaki, Hideo; Papina, Marina; Van Woesik, Robert

2003-05-01

158

Mid-infrared Atomic Fine-structure Emission-line Spectra of Luminous Infrared Galaxies: Spitzer/IRS Spectra of the GOALS Sample  

NASA Astrophysics Data System (ADS)

We present the data and our analysis of mid-infrared atomic fine-structure emission lines detected in Spitzer/Infrared Spectrograph high-resolution spectra of 202 local Luminous Infrared Galaxies (LIRGs) observed as part of the Great Observatories All-sky LIRG Survey (GOALS). We readily detect emission lines of [S IV], [Ne II], [Ne V], [Ne III], [S III]18.7 ?m, [O IV], [Fe II], [S III]33.5 ?m, and [Si II]. More than 75% of these galaxies are classified as starburst-dominated sources in the mid-infrared, based on the [Ne V]/[Ne II] line flux ratios and equivalent width of the 6.2 ?m polycyclic aromatic hydrocarbon feature. We compare ratios of the emission-line fluxes to those predicted from stellar photo-ionization and shock-ionization models to constrain the physical and chemical properties of the gas in the starburst LIRG nuclei. Comparing the [S IV]/[Ne II] and [Ne III]/[Ne II] line ratios to the Starburst99-Mappings III models with an instantaneous burst history, the emission-line ratios suggest that the nuclear starbursts in our LIRGs have ages of 1-4.5 Myr, metallicities of 1-2 Z ?, and ionization parameters of 2-8 107 cm s1. Based on the [S III]33.5 ?m/[S III]18.7 ?m ratios, the electron density in LIRG nuclei is typically one to a few hundred cm3, with a median electron density of ~300 cm3, for those sources above the low density limit for these lines. We also find that strong shocks are likely present in 10 starburst-dominated sources of our sample. A significant fraction of the GOALS sources (80) have resolved neon emission-line profiles (FWHM >=600 km s1) and five show clear differences in the velocities of the [Ne III] or [Ne V] emission lines, relative to [Ne II], of more than 200 km s1. Furthermore, six starburst and five active galactic nucleus dominated LIRGs show a clear trend of increasing line width with ionization potential, suggesting the possibility of a compact energy source and stratified interstellar medium in their nuclei. We confirm a strong correlation between the sum of the [Ne II]12.8 ?m and [Ne III]15.5 ?m emission, as well as [S III]33.5 ?m, with both the infrared luminosity and the 24 ?m warm dust emission measured from the spectra, consistent with all three lines tracing ongoing star formation. Finally, we find no correlation between the hardness of the radiation field or the emission-line width and the ratio of the total infrared to 8 ?m emission (IR8), a measure of the strength of the starburst and the distance of the LIRGs from the star-forming main sequence. This may be a function of the fact that the infrared luminosity and the mid-infrared fine-structure lines are sensitive to different timescales over the starburst, or that IR8 is more sensitive to the geometry of the region emitting the warm dust than the radiation field producing the H II region emission.

Inami, H.; Armus, L.; Charmandaris, V.; Groves, B.; Kewley, L.; Petric, A.; Stierwalt, S.; Daz-Santos, T.; Surace, J.; Rich, J.; Haan, S.; Howell, J.; Evans, A. S.; Mazzarella, J.; Marshall, J.; Appleton, P.; Lord, S.; Spoon, H.; Frayer, D.; Matsuhara, H.; Veilleux, S.

2013-11-01

159

Effect of precursor mineralogy on the thermal infrared emission spectra of hematite: Application to Martian hematite mineralization  

NASA Astrophysics Data System (ADS)

Observations from the Thermal Emission Spectrometer (TES) instrument aboard the Mars Global Surveyor (MGS) spacecraft led to the discovery of two isolated deposits of gray, crystalline hematite located in Meridiani Planum and Aram Chaos and several smaller deposits in Valles Marineris. Several pathways for formation of these hematite deposits have been proposed, involving both aqueous and nonaqueous processes. This work uses the precise shape and position of spectral features in the Martian hematite thermal emission spectrum to constrain hematite formation pathways. Thermal infrared emission spectra, X-ray powder diffraction patterns, Mssbauer spectra, and transmission electron microscope (TEM) photomicrographs were obtained for synthetic and natural hematite samples derived by (1) dehydroxylation of fine-grained goethite and (2) oxidation of magnetite. Collectively, the instrumental analyses show that the mineralogical composition and crystal morphology of precursor samples and the time and temperature conditions under which decomposition to hematite occur determine the crystallinity and crystal morphology of the hematite product. Comparison of laboratory and MGS-TES spectra shows that the Martian hematite spectra correspond closely with a synthetic hematite sample derived by pseudomorphic and topotactic dehydroxylation of goethite at 300C. Spectra of goethite-precursor samples dehydroxylated at higher temperatures provide increasingly poor fits. Spectra of hematite samples derived by high-temperature thermal oxidation of magnetite are also poorer fits to the Martian hematite spectrum. Thermal emission spectra of goethites heated at lower temperatures are characterized by the spectral signatures of both hematite and goethite and are not consistent with the Martian spectra. The characteristic that distinguishes the synthetic hematite sample with the Mars-like spectral signature from the other synthetic hematite samples is the high proportion of crystal surfaces that are crystallographic {001} faces (c faces) for the former but not the latter. The high proportion of {001} face area results because the largest surface of the lath-shaped hematite particles is the (001) face, as determined by TEM. Thus a possible formation pathway for hematite in Meridiani Planum, Aram Chaos, and Valles Marineris is precipitation of goethite from aqueous solutions as lath-shaped crystals, possibly as a stain, cement, and/or massive deposit, followed by pseudomorphic and topotactic dehydroxylation to hematite at temperatures below ~300C.

Glotch, T. D.; Morris, R. V.; Christensen, P. R.; Sharp, T. G.

2004-07-01

160

Development of a high-efficiency high-resolution particle-induced x-ray emission system for chemical state analysis of environmental samples  

SciTech Connect

We have developed a high-efficiency high-resolution particle-induced x-ray emission (PIXE) system employing a von Hamos-type crystal spectrometer for a chemical state identification of trace elements in environmental samples. The energy resolution of the system was determined to be about 0.05% through the observation of Si K{alpha}{sub 1,2} x rays (1.74 keV) from elemental silicon. The throughput efficiency of the system was also evaluated quasitheoretically to be 1.6x10{sup -7} counts/incident proton for Si K{alpha}{sub 1,2} emission. To demonstrate a chemical state analysis using the high-resolution PIXE system, Si K{alpha}{sub 1,2} and K{beta} x-ray spectra for SiC, Si{sub 3}N{sub 4}, and SiO{sub 2} were measured and compared. The observed chemical shifts of the Si K{alpha}{sub 1,2} peaks for SiC, Si{sub 3}N{sub 4}, and SiO{sub 2} relative to elemental silicon were 0.20, 0.40, and 0.55 eV, respectively. The tendency of these shifts were well explained by the effective charges of the silicon atoms calculated by a molecular orbital method.

Hasegawa, J.; Tada, T.; Oguri, Y.; Hayashi, M.; Toriyama, T.; Kawabata, T.; Masai, K. [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan); Musashi Institute of Technology, 1-28-1 Tamazutsumi, Setagaya-ku, Tokyo 158-8557 (Japan)

2007-07-15

161

The energy distribution in the emission spectra of the nuclei of planetary nebulae beyond the Lyman limit  

NASA Astrophysics Data System (ADS)

The energy distribution in the spectra of the nuclei of 29 planetary nebulae beyond the Lyman limit is calculated from the observed intensities of the He II 4686 A and H-beta lines. The energy balance and Zanstra equations are used and modified in the case of a helium admixture. The emission jump discovered in the radiation of some nuclei at 228 A is analyzed. It is concluded that the energy distribution in the emission spectrum of the nuclei of the planetary nebulae at lambda less than 912 A can be used as a first approximation in the construction of photoionization models of the luminescence of these objects.

Golovaty, V. V.

1987-07-01

162

Effects of Weathering on Basaltic Rocks and Their Thermal Emission Spectra: Implications for Evaluating Mars Mineralogy and Weathering  

NASA Astrophysics Data System (ADS)

Thermal emission spectroscopy has provided crucial information about the mineralogical composition of the Martian surface. Portions of that surface may be chemically weathered, and it is, therefore, important that the influence of chemical weathering on thermal infrared observations be recognized and understood. To this end, we have examined a suite of weathered rocks collected from the Columbia River Basalt Group. Weathering causes distinct changes to the thermal emissivity spectra of these basalts, which will be discussed in detail by J. R. Michalski et al. (this meeting). Here, we document physical and mineralogical features of weathering rinds to understand how weathering affects infrared spectra. Chemical weathering of basalts forms microcracks, dissolves primary minerals, and produces secondary phases. In the rocks examined, the relative abundance of primary minerals is the same in the weathering rind and corresponding unweathered rock. This is true even for olivine, the least stable phase in the rocks studied. Thus, preferential dissolution is not a controlling factor in the observed spectral changes. Microcracks form by expansion and dissolution and represent <20 vol% of the weathering rinds studied. While they potentially act as blackbody cavities, they probably influence emissivity spectra more by acting as sites where secondary phases form. Because the cracks are generally a few micrometers in width, the secondary phases filling them are optically thin, which may produce nonlinearity in spectral mixing of mineral phases, complicating spectral modeling. Secondary phases are Si-Al-rich and strongly influence the Si-O stretching region of infrared spectra. Dissolution of silica from primary phases and its precipitation in microcracks are the principle factors controlling changes in emissivity spectra in weathered rocks. These changes can lead to inaccurate relative abundances of primary phases derived from deconvolution modeling of weathered rocks. Also, the secondary silicates are generally amorphous to poorly crystalline, and deconvolution modeling misinterprets these materials as silicate glasses and clay minerals. The exact effects weathering exerts on emissivity spectra and subsequent modeling results will depend on what secondary silicates form, particularly how much silica is present, which will in turn depend on the conditions of weathering. However, the basic scenario of crack formation and mineralogical redistribution of silica should hold for a wide range of weathering conditions, and similar effects are expected for weathered Martian surfaces.

Kraft, M. D.; Michalski, J. R.; Sharp, T. G.

2005-12-01

163

The effect of Fe, Cu, and Si impurities on the formation of emission spectra in bulk ZnO crystals  

SciTech Connect

On the basis of the results of complex investigations (photoluminescence, x-ray fluorescence, and infrared spectroscopy), the features of emission-spectra formation are shown under the change in the type (Fe, Cu, and Si) and concentration of background impurities appearing during both growth and treatment of bulk crystals by grinding and polishing. Special attention is given to the concentration and types of bonds with hydrogen-the basic impurity preventing the formation of crystals with the p-type conductivity.

Mezdrogina, M. M., E-mail: margaret.m@mail.ioffe.ru; Danilevskii, E. Yu.; Kuz'min, R. V.; Poletaev, N. K.; Trapeznikova, I. N. [Ioffe Physicotechnical Institute (Russian Federation); Chukichev, M. V. [Moscow State University (Russian Federation); Bordovskii, G. A.; Marchenko, A. V. [Russian State Pedagogical University (Russian Federation); Eremenko, M. V. [St. Petersburg State Polytechnical University (Russian Federation)

2010-04-15

164

Infrared spectra and circumstellar emission of late-type stars. II - IRAS carbon stars. III - S-type stars  

Microsoft Academic Search

We carried out near-infrared photometry of the J, H, K, L, and 3.1- mum bands for 67 IRAS sources which have a 11.3-mum emission feature due to silicon carbide dust in their IRAS low-resolution spectra. Since these stars have no optical counterpart, most of them are considered to be carbon stars surrounded, and thus obscured, by thick circumstellar dust envelopes.

Kunio Noguchi; Jinghao Sun; Gang Wang

1991-01-01

165

X-ray K ? 1 emission spectra of sulfur in dialkyl sulfides and some heterocyclic compounds of sulfur  

Microsoft Academic Search

The x-ray K~ffemission spectra were obtained for the sulfur in dialkyl sulfides RzS (where R = CH~, C2Hs, C4H9, C6H13, CsHIT), diphenyl sulfide, and some heterocyclic compounds. By comparison with calculations the emission peaks were assigned to electronic transitions from levels of corresponding symmetry. In the unsaturated compounds interaction was detected between the unshared electron pair of the sulfur atom

L. N. Mazalov; A. P. Sadovskii; . A. Gal'tsova; V. V. Murakhtanov; V. G. Torgov; V. M. Bertenev; A. P. Zeif

1973-01-01

166

Passive Fourier transform infrared (FTIR) monitoring of SO2 in smokestack plumes: a comparison of remote passive spectra of an actual hot plume with emission spectra collected with a heatable cell  

Microsoft Academic Search

In the interest of developing practical methodologies for remote passive FT-IR analysis of sulfur dioxide in heated smoke stack plumes, IR spectra have been collected in a number of relevant experiments. Field data includes passive remote FT-IR spectra collected at a coal-burning power plant for which plume conditions were characterized by in-stack continuous emission monitors (CEMs), spectra collected of a

Charles T. Chaffin; T. L. Marshall; R. J. Combs; R. B. Knapp; Robert T. Kroutil; William G. Fateley; Robert M. Hammaker

1995-01-01

167

Observation of ? backbonding features appearing in Fe 2p X-ray absorption spectra and Fe 1s-4p-1s resonant X-ray emission spectra of RbMn[Fe(CN)6  

NASA Astrophysics Data System (ADS)

Satellite features by p backbonding (metal-to-ligand charge transfer) were observed in both Fe 2p (L3,2-edge) X-ray absorption spectra and 1s-4p-1s resonant X-ray emission spectra for RbMn[Fe(CN)6], which can be theoretically explained using common parameters. Fe L3,2-edge and Mn L3,2-edge X-ray absorption spectra for low temperature phase are also presented.

Kitajima, Yoshinori; Nanba, Y?suke; Tanaka, Masayuki; Koga, Yuji; Ueno, Akihiro; Nakagawa, Kosuke; Tokoro, Hiroko; Ohkoshi, Shin-ichi; Iwazumi, Toshiaki; Okada, Kozo; Isozumi, Yasuhito

2013-04-01

168

Time-resolved measurements of near infrared emission spectra from explosions: Pure pentaerythritol tetranitrate and its mixtures containing silver and aluminum particles  

NASA Astrophysics Data System (ADS)

Measurements of chemical transients and thermodynamic conditions are difficult to obtain yet fundamentally important in understanding the behavior of explosives. We have constructed a fast near infrared (NIR) spectrometer and have made temporally and spectrally-resolved emission measurements during postdetonation combustion of pure pentaerythritol tetranitrate (PETN) charges and PETN charges doped with 10 wt % microparticles composed of silver (Ag) and aluminum (Al). We have observed postdetonation PETN emission spectra between 750 and 1500 nm at rates up to 46 992 spectra/s. The instrument captures the highly structured spectra immediately following breakout as well as the longer-lived broadband NIR emission signals from hot particles. The early spectra reveal spectral signatures related to PETN and the reacting constituents of the particles. The later spectra provide a means to infer the gray-body temperature history of the particles.

Koch, Jon D.; Piecuch, Scott; Lightstone, James M.; Carney, Joel R.; Hooper, Joe

2010-08-01

169

Emission spectra of Rb{sup *}He{sub n} exciplexes in a cold {sup 4}He gas  

SciTech Connect

We report on the systematic observation of emission spectra of Rb{sup *}He{sub n} exciplexes (n=1,2,...,6), realized by exciting Rb atoms to the 5{sup 2}P states (Rb{sup *}) in a cold {sup 4}He gas. The observed broad spectral components are assigned to Rb{sup *}He{sub n} (n=1-6) using theoretical spectra obtained from ab initio potential curves. The dynamics of the exciplex formation is discussed, based on the observed temperature dependence of the spectra. The He gas density dependence of the spectra of Rb{sup *}He is understood as a change in the population distribution over the vibrational levels. The present results are compared with our previous work with Cs [K. Enomoto et al., Phys. Rev. A 66, 042505 (2002)], and differences are explained in terms of the difference in the fine-structure splitting. Furthermore, we show the emission spectrum observed after the excitation of Rb in liquid He and conclude that it is the fluorescence from the exciplex Rb{sup *}He{sub 6}.

Hirano, K.; Enomoto, K.; Kumakura, M.; Takahashi, Y.; Yabuzaki, T. [Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, (Japan)

2003-07-01

170

Determination of vibrational and rotational temperatures in a gliding arc discharge by using overlapped molecular emission spectra  

NASA Astrophysics Data System (ADS)

Vibrational and rotational temperatures were simultaneously determined in a kilohertz alternating current (ac) gliding arc discharge by using overlapped emission spectra of N2(C 3?u-B 3?g) with OH(A 2?+-X 2?i) and with N_{2}^{+} (B\\,{}^{2}\\!\\Sigma_{u}^{+} {--}X\\,{}^{2}\\!\\Sigma_{g}^{+} ) . The simulated emission spectra of OH(A 2?+-X 2?i) and N_{2}^{+} (B\\,{}^{2}\\!\\Sigma_{u}^{+} {--}X\\,{}^{2}\\!\\Sigma_{g}^{+} ) were largely overlapped by radiation transition bands of N2(C 3?u-B 3?g) when the rotational temperature was elevated from 500 K to 2500 K. The temporally resolved vibrational and rotational temperatures in a discharge voltage period suggested that the rotational temperature from OH(A 2?+-X 2?i) was remarkably larger than that from N2(C 3?u-B 3?g) and N_{2}^{+} (B\\,{}^{2}\\!\\Sigma_{u}^{+}{--}X\\,{}^{2}\\!\\Sigma_{g}^{+}) . The ratio of number densities of excited electronic states was also determined based on the overlapped emission spectra.

Zhao, Tian-Liang; Xu, Yong; Song, Yuan-Hong; Li, Xiao-Song; Liu, Jing-Lin; Liu, Jin-Bao; Zhu, Ai-Min

2013-08-01

171

HST-COS OBSERVATIONS OF AGNs. I. ULTRAVIOLET COMPOSITE SPECTRA OF THE IONIZING CONTINUUM AND EMISSION LINES  

SciTech Connect

The ionizing fluxes from quasars and other active galactic nuclei (AGNs) are critical for interpreting the emission-line spectra of AGNs and for photoionization and heating of the intergalactic medium. Using ultraviolet spectra from the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST), we have directly measured the rest-frame ionizing continua and emission lines for 22 AGNs. Over the redshift range 0.026 < z < 1.44, COS samples the Lyman continuum and many far-UV emission lines (Ly{alpha} {lambda}1216, C IV {lambda}1549, Si IV/O IV] {lambda}1400, N V {lambda}1240, O VI {lambda}1035). Strong EUV emission lines with 14-22 eV excitation energies (Ne VIII {lambda}{lambda}770, 780, Ne V {lambda}569, O II {lambda}834, O III {lambda}833, {lambda}702, O IV {lambda}788, 608, 554, O V {lambda}630, N III {lambda}685) suggest the presence of hot gas in the broad emission-line region. The rest-frame continuum, F{sub {nu}}{proportional_to}{nu}{sup {alpha}{sub {nu}}}, shows a break at wavelengths {lambda} < 1000 A, with spectral index {alpha}{sub {nu}} = -0.68 {+-} 0.14 in the FUV (1200-2000 A) steepening to {alpha}{sub {nu}} = -1.41 {+-} 0.21 in the EUV (500-1000 A). The COS EUV index is similar to that of radio-quiet AGNs in the 2002 HST/FOS survey ({alpha}{sub {nu}} = -1.57 {+-} 0.17). We see no Lyman edge ({tau}{sub HI} < 0.03) or He I {lambda}584 emission in the AGN composite. Our 22 AGNs exhibit a substantial range of FUV/EUV spectral indices and a correlation with AGN luminosity and redshift, likely due to observing below the 1000 A spectral break.

Shull, J. Michael; Stevans, Matthew; Danforth, Charles W., E-mail: michael.shull@colorado.edu, E-mail: matthew.stevans@colorado.edu, E-mail: charles.danforth@colorado.edu [CASA, Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309 (United States)

2012-06-20

172

A VLBA SEARCH FOR BINARY BLACK HOLES IN ACTIVE GALACTIC NUCLEI WITH DOUBLE-PEAKED OPTICAL EMISSION LINE SPECTRA  

SciTech Connect

We have examined a subset of 11 active galactic nuclei (AGNs) drawn from a sample of 87 objects that possess double-peaked optical emission line spectra, as put forward by Wang et al. and are detectable in the Faint Images of the Radio Sky at Twenty-centimeters (FIRST) survey at radio wavelengths. The double-peaked nature of the optical emission line spectra has been suggested as evidence for the existence of binary black holes in these AGNs, although this interpretation is controversial. We make a simple suggestion that direct evidence of binary black holes in these objects could be searched for in the form of dual sources of compact radio emission associated with the AGNs. To explore this idea, we have used the Very Long Baseline Array to observe these 11 objects from the Wang et al. sample. Of the 11 objects, we detect compact radio emission from two, SDSS J151709+335324 and SDSS J160024+264035. Both objects show single components of compact radio emission. The morphology of SDSS J151709+335324 is consistent with a recent comprehensive multi-wavelength study of this object by Rosario et al. Assuming that the entire sample consists of binary black holes, we would expect of order one double radio core to be detected, based on radio wavelength detection rates from FIRST and very long baseline interferometry surveys. We have not detected any double cores, thus this work does not substantially support the idea that AGNs with double-peaked optical emission lines contain binary black holes. However, the study of larger samples should be undertaken to provide a more secure statistical result, given the estimated detection rates.

Tingay, S. J.; Wayth, R. B., E-mail: s.tingay@curtin.edu.au [International Centre for Radio Astronomy Research, Curtin University, Bentley, WA (Australia)

2011-06-15

173

Aerosol-fluorescence spectrum analyzer: real-time measurement of emission spectra of airborne biological particles  

NASA Astrophysics Data System (ADS)

We have assembled an aerosol-fluorescence spectrum analyzer (AFS), which can measure the fluorescence spectra and elastic scattering of airborne particles as they flow through a laser beam. The aerosols traverse a scattering cell where they are illuminated with intense (50 kW/cm 2) light inside the cavity of an argon-ion laser operating at 488 nm. This AFS can obtain fluorescence spectra of individual dye-doped polystyrene microspheres as small as 0.5 mu m in diameter. The spectra obtained from microspheres doped with pink and green-yellow dyes are clearly different. We have also detected the fluorescence spectra of airborne particles (although not single particles) made from various

Hill, Steven C.; Pinnick, Ronald G.; Nachman, Paul; Chen, Gang; Chang, Richard K.; Mayo, Michael W.; Fernandez, Gilbert L.

1995-10-01

174

Strong Calcite-Like Spectra Cathodoluminescence Emission from Allende Meteorite Cai Phases  

Microsoft Academic Search

Calciumaluminum-rich inclusions (CAIs) of Allende CV3 chondrite were studied by Environmental Scanning Electron Microscopy (ESEM), Energy Dispersive Spectrometry (EDS), Backscattering (BS), and Spectra Cathodoluminescence (CL). CAI minerals show spectra CL curves exceeding the 450,000a.u. with a large homogeneity along the white inclusions. CL curve features fit perfectly with terrestrial patterns of stressed specimens of weathered marble and limestone in which

Javier Garcia-Guinea; Laura Tormo; Oscar Azumendi; Javier Ruiz; Virgilio Correcher

2011-01-01

175

Retrieval of temperature and tangent altitude pointing from limb emission spectra recorded from space by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS)  

Microsoft Academic Search

Retrieval of abundances of atmospheric species from limb infrared emission spectra requires accurate knowledge of the pointing of the instrument in terms of elevation, as well as temperature and pressure profiles. An optimal estimation-based method is presented to infer these quantities from measured spectra. The successful and efficient joint retrieval of these largely correlated quantities depends strongly on the proper

T. von Clarmann; N. Glatthor; U. Grabowski; M. Hpfner; S. Kellmann; M. Kiefer; A. Linden; G. M. Tsidu; M. Milz; T. Steck; G. P. Stiller; D. Y. Wang; H. Fischer; B. Funke; S. Gil-Lpez; M. Lpez-Puertas

2003-01-01

176

Effects of hydrogen dissociation on the infrared emission spectra of naphthalene: theoretical modeling.  

PubMed

The IR emission spectroscopy of naphthalene and its singly- and doubly-dehydrogenated radicals has been modeled using kinetic Monte Carlo simulations, taking into account the various relaxation pathways of radiative emission and hydrogen loss. Our modeling relies on quantum chemistry ingredients that were obtained from dedicated calculations based on density functional theory, including explicitly anharmonicity contributions. Our results show that the fragmentation products significantly contribute to the overall IR emission spectrum, especially to the intensity ratios between bands. Owing to the likely presence of polycyclic aromatic hydrocarbons in the interstellar medium, these findings are particularly relevant in the astrophysical context. PMID:23552801

Falvo, Cyril; Friha, Hela; Pino, Thomas; Dhaouadi, Zoubeida; Parneix, Pascal; Calvo, Florent; Brchignac, Philippe

2013-04-04

177

Chemical Environment Effects on K[beta]/K[alpha] Intensity Ratio: An X-Ray Fluorescence Experiment on Periodic Trends  

ERIC Educational Resources Information Center

|X-ray fluorescence (XRF) data from an energy-dispersive XRF instrument were used to investigate the chlorine K[alpha] and K[beta] peaks in several group 1 salts. The ratio of the peak intensity is sensitive to the local chemical environment of the chlorine atoms studied in this experiment and it shows a periodic trend for these salts. (Contains 1

Durham, Chaney R.; Chase, Jeffery M.; Nivens, Delana A.; Baird, William H.; Padgett, Clifford W.

2011-01-01

178

Far Ultraviolet Emission Line Spectra of the Vela Super Nova Remnant  

NASA Astrophysics Data System (ADS)

We present FUV emission line images at 6 different wavelengths obtained with a diffuse imaging spectrometer (SPEAR) and compare them to ROSAT and EUVE FUV maps. Spatial differences in the temperature structure are investigated.

Sirk, Martin M.; Edelstein, J.; Min, K.; Han, W.; SPEAR Team

2007-12-01

179

Modeling the anharmonic infrared Emission Spectra of PAHs: Application to the Pyrene Cation  

NASA Astrophysics Data System (ADS)

The IR emission cascade from the pyrene cation due to a broad band optical excitation is simulated using kinetic Monte Carlo. Anharmonicities of the ground electronic state potential energy surface are taken into account in the transition energies, the microcanonical densities of states, and the rate of hydrogen loss through various statistical theories. The emission spectral features of the "3.3", "6.2" and "11.2" ?m bands are computed for different blackbody temperatures.

Basire, M.; Parneix, P.; Pino, T.; Brchignac, Ph.; Calvo, F.

2011-03-01

180

A new non-LTE retrieval method for atmospheric parameters from mipas-envisat emission spectra  

Microsoft Academic Search

The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) is a high-resolution limb sounder on board the European polar platform ENVISAT, scheduled to be launched in 2001. A large number of atmospheric trace gases relevant to stratospheric ozone chemistry and global change are expected to be retrieved from the IR spectra covering a wide spectral range. While operational data analysis under

B. Funke; M. Lpez-Puertas; G. Stiller; T. V. Clarmann; M. Hpfner

2001-01-01

181

Plasma Emission Spectra of Opuntia Nopalea Obtained with Microsecond Laser Pulses  

SciTech Connect

Laser-induced Plasma Spectroscopy was performed during the spines ablation of Opuntia by using Nd:YAG microsecond laser pulses. The results show strong absorption in Glochids that causes the intense electronic noise on the spectra. This process is consider suitable for practical elimination of spines in alimentary products like opuntia.

Ponce, L.; Flores, T.; Arronte, A.; Flores, A. [CICATA-IPN, Unidad Altamira, Altamira 89600, Tamps (Mexico)

2008-04-15

182

Plasma Emission Spectra of Opuntia Nopalea Obtained with Microsecond Laser Pulses  

NASA Astrophysics Data System (ADS)

Laser-induced Plasma Spectroscopy was performed during the spines ablation of Opuntia by using Nd:YAG microsecond laser pulses. The results show strong absorption in Glochids that causes the intense electronic noise on the spectra. This process is consider suitable for practical elimination of spines in alimentary products like opuntia.

Ponce, L.; Flores, T.; Arronte, A.; Flores, A.

2008-04-01

183

How to Collect National Institute of Standards and Technology (NIST) Traceable Fluorescence Excitation and Emission Spectra.  

PubMed

Contemporary spectrofluorimeters comprise exciting light sources, excitation and emission monochromators, and detectors that without correction yield data not conforming to an ideal spectral response. The correction of the spectral properties of the exciting and emission light paths first requires calibration of the wavelength and spectral accuracy. The exciting beam path can be corrected up to the sample position using a spectrally corrected reference detection system. The corrected reference response accounts for both the spectral intensity and drift of the exciting light source relative to emission and/or transmission detector responses. The emission detection path must also be corrected for the combined spectral bias of the sample compartment optics, emission monochromator, and detector. There are several crucial issues associated with both excitation and emission correction including the requirement to account for spectral band-pass and resolution, optical band-pass or neutral density filters, and the position and direction of polarizing elements in the light paths. In addition, secondary correction factors are described including (1) subtraction of the solvent's fluorescence background, (2) removal of Rayleigh and Raman scattering lines, as well as (3) correcting for sample concentration-dependent inner-filter effects. The importance of the National Institute of Standards and Technology (NIST) traceable calibration and correction protocols is explained in light of valid intra- and interlaboratory studies and effective spectral qualitative and quantitative analyses including multivariate spectral modeling. PMID:24108620

Gilmore, Adam Matthew

2014-01-01

184

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

185

Characterization of high-resolution aerosol mass spectra of primary organic aerosol emissions from Chinese cooking and biomass burning  

NASA Astrophysics Data System (ADS)

Aerosol Mass Spectrometer (AMS) has proved to be a powerful tool to measure submicron particulate composition with high time resolution. Factor analysis of mass spectra (MS) collected worldwide by AMS demonstrates that submicron organic aerosol (OA) is usually composed of several major components, such as oxygenated (OOA), hydrocarbon-like (HOA), biomass burning (BBOA), and other primary OA. In order to help interpretation of component MS from factor analysis of ambient OA datasets, AMS measurement of different primary sources is required for comparison. Such work, however, has been very scarce in the literature, especially for high resolution MS (HR-MS) measurement, which performs improved characterization by separating the ions of different elemental compositions at each m/z in comparison with unit mass resolution MS (UMR-MS) measurement. In this study, primary emissions from four types of Chinese cooking (CC) and six types of biomass burning (BB) were simulated systemically and measured using an Aerodyne High-Resolution Time-of-Flight AMS (HR-ToF-AMS). The MS of the CC emissions show high similarity with m/z 41 and m/z 55 being the highest signals; the MS of the BB emissions also show high similarity with m/z 29 and m/z 43 being the highest signals. The MS difference between the CC and BB emissions is much bigger than that between different CC (or BB) types, especially for the HR-MS. The O/C ratio of OA ranges from 0.08 to 0.13 for the CC emissions while from 0.18 to 0.26 for the BB emissions. The ions of m/z 43, m/z 44, m/z 57, and m/z 60, usually used as tracer ions in AMS measurement, were examined for their HR-MS characteristics in the CC and BB emissions. Moreover, the MS of the CC and BB emissions are also used to compare with component MS from factor analysis of ambient OA datasets observed in China, as well as with other AMS measurements of primary sources in the literature. The MS signatures of cooking and biomass burning emissions revealed in this study can be used as important reference in factor analysis of ambient OA datasets, especially for the relevant studies in East Asia.

He, L.-Y.; Lin, Y.; Huang, X.-F.; Guo, S.; Xue, L.; Su, Q.; Hu, M.; Luan, S.-J.; Zhang, Y.-H.

2010-09-01

186

Characterization of high-resolution aerosol mass spectra of primary organic aerosol emissions from Chinese cooking and biomass burning  

NASA Astrophysics Data System (ADS)

Aerosol mass spectrometry has proved to be a powerful tool to measure submicron particulate composition with high time resolution. Factor analysis of mass spectra (MS) collected worldwide by aerosol mass spectrometer (AMS) demonstrates that submicron organic aerosol (OA) is usually composed of several major components, such as oxygenated (OOA), hydrocarbon-like (HOA), biomass burning (BBOA), and other primary OA. In order to help interpretation of component MS from factor analysis of ambient OA datasets, AMS measurements of different primary sources is required for comparison. Such work, however, has been very scarce in the literature, especially for high resolution MS (HR-MS) measurements, which performs improved characterization by separating the ions of different elemental composition at each m/z in comparison with unit mass resolution MS (UMR-MS) measurements. In this study, primary emissions from four types of Chinese cooking (CC) and six types of biomass burning (BB) were simulated systematically and measured using an Aerodyne High-Resolution Time-of-Flight AMS (HR-ToF-AMS). The MS of the CC emissions show high similarity, with m/z 41 and m/z 55 being the highest signals; the MS of the BB emissions also show high similarity, with m/z 29 and m/z 43 being the highest signals. The MS difference between the CC and BB emissions is much bigger than that between different CC (or BB) types, especially for the HR-MS. The O/C ratio of OA ranges from 0.08 to 0.13 for the CC emissions and from 0.18 to 0.26 for the BB emissions. The UMR ions of m/z 43, m/z 44, m/z 57, and m/z 60, usually used as tracers in AMS measurements, were examined for their HR-MS characteristics in the CC and BB emissions. In addition, the MS of the CC and BB emissions are also compared with component MS from factor analysis of ambient OA datasets observed in China, as well as with other AMS measurements of primary sources in the literature. The MS signatures of cooking and biomass burning emissions revealed in this study can be used as important reference for factor analysis of ambient OA datasets, especially for the relevant studies in East Asia.

He, L.-Y.; Lin, Y.; Huang, X.-F.; Guo, S.; Xue, L.; Su, Q.; Hu, M.; Luan, S.-J.; Zhang, Y.-H.

2010-12-01

187

Automatic identification of emission lines in laser-induced plasma by correlation of model and experimental spectra.  

PubMed

We have applied an algorithm to automatically identify emission lines in laser-induced breakdown spectrometry (LIBS). A Q-switched Nd:YAG laser at 355 nm was used to ablate a high-alloy stainless steel sample. The algorithm was implemented by three parts: simulation of the set of spectra corresponding to different temperature (T) and electron density (N(e)), searching the best correlated pair of a model spectrum and an experimental one, and attributing the peaks with certain lines. In order to construct the model spectra, we used the parameters of atomic and ionic lines, levels, the mechanisms of the broadening of spectral lines, and the selected parameters of the spectrograph. The highest correlation coefficient between the model and the experimental spectrum was 0.943 for T = 0.675 eV and lg(N(e)) = 16.7 cm(-3). More than 40 emission lines were labeled automatically in the spectral region 393.34-413.04 nm. PMID:23343435

Labutin, Timur A; Zaytsev, Sergey M; Popov, Andrey M

2013-01-25

188

Enhanced inner-shell x-ray emission by femtosecond-laser irradiation of solid cone targets  

SciTech Connect

The possibility of enhancing inner-shell x-ray emission, especially K{alpha} emission, by femtosecond-laser irradiation of solid cones instead of foils was investigated theoretically. In a model for hot electron (HE) transport and K{alpha} x-ray generation, K{alpha} emission from laser-irradiated solid cones and foils is investigated. As a complementarity to the model, the contributions from electric and magnetic fields generated by the HE current in solid cones and foils are discussed. The results indicate that the efficiency of HE energy conversion to K{alpha} photons is improved and the optimum HE temperature is increased.

Li Xiaoya; Zhu Wenjun; Ye Yan; Li Jun; Yu Yong [National Key Laboratory of Shock Wave and Detonation Physics, Mianyang, 621900 Sichuan (China); Wang Jiaxiang [State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062 (China)

2011-04-15

189

Emission spectra of high-current vacuum arc stabilized by axial magnetic field  

Microsoft Academic Search

Measurements of radiation spectra of a high-current vacuum arc with copper electrodes with high temporal and spatial resolution were done in wide spectral interval. Freely burning arcs and those stabilized with the external uniform axial magnetic field at I les 7 kA, B les 0.2 T were studied. Radial distributions of the excitation temperature of atomic and ionic components in

V. A. Bugaev; V. L. Dernovskij; A. A. Logatchev; K. K. Zabello; S. M. Shkol'nik

2008-01-01

190

New Chandra observations of the jet in 3C273. 1. Softer X-ray than radio spectra and the X-ray emission mechanism  

Microsoft Academic Search

The jet in 3C273 is a high-power quasar jet with radio, optical and X-ray emission whose size and brightness allow a detailed study of the emission processes acting in it. We present deep Chandra observations of this jet and analyze the spectral properties of the jet emission from radio through X-rays. We find that the X-ray spectra are significantly softer

Sebastian Jester; D. E. Harris; H. L. Marshall; K. Meisenheimer

2006-01-01

191

Constraining thermal dust emission in distant galaxies with number counts and angular power spectra  

NASA Astrophysics Data System (ADS)

We perform a joint fit to differential number counts from Spitzer's Multiband Imaging Photometer for Spitzer and Herschel's Spectral and Photometric Imaging Receiver (SPIRE) instruments, and angular power spectra of cosmic infrared background (CIB) anisotropies from SPIRE, Planck, the Atacama Cosmology Telescope and the South Pole Telescope, which together span 220? ? /{GHz}? 4300 (70? ? /? {m}? 1400). We simultaneously constrain the dust luminosity function, thermal dust spectral energy distribution (SED) and clustering properties of CIB sources, and the evolution of these quantities over cosmic time. We find that the data strongly require redshift evolution in the thermal dust SED. In our adopted parametrization, this evolution takes the form of an increase in greybody dust temperature at high redshift, but it may also be related to a temperature - dust luminosity correlation or evolution in dust opacity. The counts and spectra together constrain the evolution of the thermal dust luminosity function up to z 2.5-3, complementing approaches relying on rest-frame mid-infrared observations of the rarest bright objects. We are able to fit the power spectra without requiring a complex halo model approach, and show that neglecting scale-dependent halo bias may be impairing analyses that do use this framework.

Addison, G. E.; Dunkley, J.; Bond, J. R.

2013-10-01

192

Designer emission spectra through tailored energy transfer in nanoparticle-doped silica preforms.  

PubMed

This Letter provides a qualitative proof of concept for purposefully tailoring the emission spectrum of glass by spatially localizing dissimilar dopants to control the degree of energy transfer. More specifically, modified-chemical-vapor-deposition-derived silica preforms were solution doped with either a solution of individually Eu(3+)- or Tb(3+)-doped nanoparticles or a solution of Eu(3+)/Tb(3+)-codoped nanoparticles. The preform prepared using the codoped nanoparticles exhibited energy transfer from the Tb(3+) to the Eu(3+) ions, whereas the preform containing individually doped nanoparticles yielded only discretely Tb(3+) or Eu(3+) emissions. The extension of this work to broadband amplifiers and lasers is discussed. PMID:19649090

Kucera, Courtney; Kokuoz, Baris; Edmondson, Dale; Griese, David; Miller, Michael; James, Andrew; Baker, William; Ballato, John

2009-08-01

193

Accuracy of plagioclase compositions from laboratory and Mars spacecraft thermal emission spectra  

Microsoft Academic Search

(1) Plagioclase, the most abundant mineral in many terrestrial and Martian igneous rocks, exhibits a range of compositions that reflects changing conditions during crystallization. Thermal emission spectrometers (TES, THEMIS, and Mini-TES) on board Mars spacecraft provide a means of determining average plagioclase compositions directly. We demonstrate that spectrally modeled average plagioclase compositions in terrestrial basalts, andesites, and dacites correspond to

Keith A. Milam; Harry Y. Mcsween; Victoria E. Hamilton; Jeffrey M. Moersch; Philip R. Christensen

2004-01-01

194

Accuracy of plagioclase compositions from laboratory and Mars spacecraft thermal emission spectra  

Microsoft Academic Search

Plagioclase, the most abundant mineral in many terrestrial and Martian igneous rocks, exhibits a range of compositions that reflects changing conditions during crystallization. Thermal emission spectrometers (TES, THEMIS, and Mini-TES) on board Mars spacecraft provide a means of determining average plagioclase compositions directly. We demonstrate that spectrally modeled average plagioclase compositions in terrestrial basalts, andesites, and dacites correspond to measured

Keith A. Milam; Harry Y. McSween Jr; Victoria E. Hamilton; Jeffrey M. Moersch; Philip R. Christensen

2004-01-01

195

DERIVING CHLOROPHYLL FLUORESCENCE EMISSIONS OF VEGETATION CANOPIES FROM HIGH RESOLUTION FIELD REFLECTANCE SPECTRA  

Technology Transfer Automated Retrieval System (TEKTRAN)

Fluorescence of foliage in the laboratory has proven more rigorous than reflectance for correlation to plant physiology. Especially useful are emissions produced from two stable red and far-red chlorophyll fluorescence (Chlorophyll fluorescence) peaks centered at 685"10 nm and 735"5 nm. Methods ha...

196

Emission Features in Moderate-Redshift QSO Spectra Shortward of Lyman alpha.  

National Technical Information Service (NTIS)

Thirty-nine IUE images were used to study emission features shortward of H I Lyman alpha in quasars. The images represent 22 moderate-redshift (0.35 less than or equal to Z less than or equal to 0.66) quasars. The features due to S VI, C III, N III, O VI ...

U. J. Sofia F. C. Bruhweiler M. Kafatos

1988-01-01

197

On emission-line spectra obtained from evolutionary synthesis models. II. Scale-relations and the estimation of mass dependences  

NASA Astrophysics Data System (ADS)

Aims: In this paper we study the influence of the ionizing cluster mass on the emission line spectrum of H ii regions in order to determine the influence of low mass clusters on the integrated emission line spectra of galaxies. Methods: For this purpose, we present a grid of photoionization models that covers metallicities from Z = 0.001 to Z = 0.040, ages from 0.1 to 10 Ma (with a time step of 0.1 Ma), and cluster initial masses from 1 to 107 M_?. The stellar masses follow a Salpeter initial mass function (IMF) in an instantaneous burst mode of star formation. We obtain power-law scale-relations between emission-line luminosities and ionizing cluster masses from the grids and we evaluate the dependences on the ionizing cluster mass for some line luminosities, equivalent widths and line ratios. Results: Power-law scale-relations are shown to be useful tools to obtain robust diagnostics, as examples: (a) H?/H? ratio varies from the usually assumed value of 2.86, these variations imply the existence of a lower limit to the attainable precision in extinction estimations of ?E(B-V) ~ 0.1; (b) EW(H?) is a good age indicator with a small dependence on cluster mass, while EW([O iii] 5007) shows a noteworthy mass dependence; (c) abundance estimations from R23 are practically unaffected by variations of the cluster mass; (d) estimations from S23 and ?' would improve if the cluster mass dependences were considered; and (e) [O ii] 3727/H? is a good star formation rate indicator for ages older than ~4.5 Ma. We also show that the ionizing cluster mass dependence explains why empirical calibrations produce more reliable diagnostics of some emission lines than photoionization models grids. Finally, we show preliminary results about the contribution of low mass clusters (M < 104 M_?) to the integrated emission line spectra of galaxies, which can be as high as 80% for some relevant lines.

Villaverde, M.; Cervio, M.; Luridiana, V.

2010-07-01

198

Alternative source of emissive CIDEP in the TREPR spectra of benzophenone in alcohols  

NASA Astrophysics Data System (ADS)

The flash photolysis EPR spectra of benzophenone (BP) in alcoholic solvents differ in terms of their chemically induced dynamic electron polarization (CIDEP) signatures when BP is photo-excited at different laser wavelengths. The difference is strongly dependent upon the concentration of BP and is attributed to the reaction of two BP triplet states to form a BP radical anion, BP radical cation pair which occurs on a timescale sufficiently rapid relative to relaxation in the BP triplet to transfer polarization into the resulting radicals. This polarized signal dominates the spectrum obtained by 266 nm photo-excitation due to the much larger extinction coefficient of BP at this wavelength.

Jones, Alex R.; Woodward, Jonathan R.

2006-05-01

199

Diagnosis of core-shell mixing with absorption and emission spectra of a doped layer. Final technical report  

SciTech Connect

Shell-core mixing which can occur during the deceleration phase of laser-driven implosion is believed to be the major limitation on target performance. The authors proposed a diagnostic method for detecting core-shell mixing based on the comparison of absorption and emission spectra due to a signature layer embedded in the target shell. Experimentally the method is simple as it does not require backlighting nor imaging. They have developed a mixing and radiation transport model used here to demonstrate the proposed diagnostic method. The proposal consists of target experiments on OMEGA as well as the interpretation and analysis of these experiments. They show that a signature layer of a high-Z dopant can be placed within the shell such that, in the absence of mixing, the emergent spectrum will only show absorption lines (of L-shell ionic species). Mixing causes the appearance of K-shell lines in emission. The more severe the mixing, the higher is the intensity of emission lines, as compared with that of the absorption lines. Modeling results are presented to demonstrate a numerical analysis of doped target experiments carried out on OMEGA.

NONE

1998-04-01

200

Emission spectra of a pulse needle-to-plane corona-like discharge in conductive aqueous solutions  

NASA Astrophysics Data System (ADS)

We explored basic optical and electrical characteristics of a positive corona-like discharge produced in conductive aqueous solutions by periodic high-voltage pulses. Emission spectra of the discharge were acquired in a needle-to-plate electrode geometry and analysed in the UV-vis-NIR spectral range with nanosecond time resolution for the solution conductivity of 100 and 500 S cm-1. The most important emission features are due to electronic excitation of HI, OI, OII and OH species. We found evidence of significant time-dependent line-shape broadening of selected HI and OI transitions. The observed broadening is attributed to the dynamic Stark and pressure broadening mechanisms and significantly increases with the aqueous solution conductivity. Electron densities were estimated by fitting a single Voigt peak function to the observed H? profiles, and can reach as much as ne ? 4 1018 cm-3 (tD = 300 ns at 100 S cm-1 solution conductivity) and ne ? 5 1018 cm-3 (tD = 1 s at 500 S cm-1). Temporal evolution of the partially resolved rotational structure of the OH emission reaches a maximum during the discharge decay, with the onset significantly delayed with respect to the streamer ignition.

imek, Milan; ?lupek, Martin; Babick, Vclav; Luke, Petr; unka, Pavel

2012-10-01

201

The K Emission Spectra for Elements Tin (50) to Hafnium (72)  

Microsoft Academic Search

Using an x-ray tube and transmission spectrograph as previously described, measurements were made of the K series emission wave-lengths of elements from Sn (50) to Hf (72), except Xe (54) and Ho (67). The beta line is resolved for most of the elements into two components beta' and beta, having a wave-length difference of about.76 x-units. The wave-length difference between

J. M. Cork; B. R. Stephenson

1926-01-01

202

The Discontinuous Drop in B Giant X-ray Emission at Spectra Type B1  

Microsoft Academic Search

B supergiants display a discontinuous drop in X-ray emission along a dividing line in the H-R diagram (analogous to the one for K giants) which is clearly related to the bi-stability jump (BSJ) at spectral type B1. Our study revealed several interesting and unexpected results, but some uncertainties have arisen since B supergiant winds are thick to soft X-rays. We

Wayne Waldron

2008-01-01

203

Study Of Titanium Emission Spectra In N2 - H2 Abnormal DC Glow Discharge  

NASA Astrophysics Data System (ADS)

In this paper we tried to answer why small amount of hydrogen (3 %) in a nitrogen abnormal glow discharge so strongly reduce Ti I spectral line intensities. Decreasing of Ti I line intensities in N2 - H2 discharge are compared with less pronounced decreasing of N I line intensities. Using emission spectroscopy we have observed that line intensity changes are correlated to variations in electron energy distribution function (EEDF) and change of metastable density.

Obradovic, B. M.; Cvetanovic, N.; Kuraica, M. M.

2010-07-01

204

Hydrogen emission-line spectra in quasars and active galactic nuclei  

Microsoft Academic Search

This paper presents a detailed analysis of the strengths of hydrogen emission lines emitted by a gas cloud for a wide range of density (N\\/sub e\\/< or =10¹³cm⁻³), temperature (10⁴ K< or =T< or approx. =3 x 10⁴ K), and ionization (10⁻⁶< or approx. = neutral fraction < or approx. =1), with an emphasis on the conditions thought to occur

J. H. Krolik; C. F. McKee

1978-01-01

205

Characterization of potentially habitable planets: Retrieval of atmospheric and planetary properties from emission spectra  

NASA Astrophysics Data System (ADS)

Context. An increasing number of potentially habitable terrestrial planets and planet candidates are found by ongoing planet search programs. The search for atmospheric signatures to establish planetary habitability and the presence of life might be possible in the future. Aims: We want to quantify the accuracy of retrieved atmospheric parameters (composition, temperature, pressure) that might be obtained from infrared emission spectroscopy. Methods: We use synthetic observations of the atmospheres of hypothetical potentially habitable planets. These were constructed with a parametrized atmosphere model, a high-resolution radiative transfer model and a simplified noise model. The simulated observations were used to fit the model parameters. Furthermore, classic statistical tools such as ?2 statistics and least-square fits were used to analyze the simulated observations. Results: When adopting the design of currently planned or proposed exoplanet characterization missions, we find that emission spectroscopy could provide weak limits on the surface conditions of terrestrial planets, hence their potential habitability. However, these mission designs are unlikely to allow the composition of the atmosphere of a habitable planet to be characterized, even though CO2 is detected. Upon increasing the signal-to-noise ratios by about a factor of 2-5 (depending on spectral resolution) compared to current mission designs, the CO2 content could be characterized to within two orders of magnitude. The detection of the O3 biosignature remains marginal. The atmospheric temperature structure could not be constrained. Therefore, a full atmospheric characterization seems to be beyond the capabilities of such missions when using only emission spectroscopy during secondary eclipse or target visits. Other methods such as transmission spectroscopy or orbital photometry are probably needed in order to give additional constraints and break degeneracies.

von Paris, P.; Hedelt, P.; Selsis, F.; Schreier, F.; Trautmann, T.

2013-03-01

206

PCI Effects on Coincidence Spectra Associated with the Emission of Two Auger Electrons  

SciTech Connect

Experimental investigation of the threshold electron / fast electron coincidences allows one to select lines which are associated with two Auger electron emission. Such an investigation carried out for near threshold photoionization of Xe 4d shell reveals a considerable distortion of the lineshapes due to Post Collision Interaction (PCI). Analysis of the PCI influence on the Auger lineshapes allows us to clarify dynamics of the two Auger electron ejection. Our study shows that both double Auger decay (DA) and cascade Auger decay (CA) could contribute to the dynamics of the decay process.

Sheinerman, S. [St. Petersburg State Maritime Technical University, 198262 St. Petersburg (Russian Federation); Lablanquie, P. [LURE, Centre Universitaire Paris-Sud, 91898 Orsay (France); Penent, F.; Hall, R.I.; Ahmad, M. [DIAM, Universite P. and M. Curie, 75252 Paris Cedex 05 (France); Hikosaka, Y.; Ito, K. [IMSS, Photon Factory, Oho 1-1, Tsukuba 305-0801 (Japan)

2003-01-24

207

Chromium-scandium multilayer mirrors for the nitrogen K(alpha) line in the water window region.  

PubMed

Chromium-scandium (Cr-Sc) is a promising material combination for multilayer mirrors in the water window region. A possible x-ray source for laboratory use in this wavelength range is the nitrogen K(alpha) line at 3.16 nm. High reflectivities at this wavelength can be achieved with Cr-Sc multilayer mirrors if the interfaces between adjacent layers are smooth. The growth parameters of the magnetron sputtering process for these materials have been optimized. It is shown that the reflectivity of such mirrors can be considerably improved by the application of a proper bias voltage during film growth. The high quality of the multilayer films is demonstrated with copper K(alpha) x-ray reflection and transmission electron microscopy. The reflective properties of the multilayers close to the nitrogen K(alpha) line were measured with synchrotron radiation for different angles of incidence. Reflectivities between R = 5.9% for near-normal incidence (theta = 1.5 degrees) and R = 29.6% for theta = 59.9 degrees were measured. PMID:11936810

Kuhlmann, Thomas; Yulin, Sergey; Feigl, Torsten; Kaiser, Norbert; Gorelik, Tatiana; Kaiser, Ute; Richter, Wolfgang

2002-04-01

208

A comparison of experiment, CEPXS/ONETRAN, TIGERP, and TIGER net electron emission coefficients for various bremsstrahlung spectra  

SciTech Connect

This work compares a carefully designed experiment to measure photoemission with the predictions of three different codes (CEPXS/ONETRAN, TIGERP, and TIGER) for the complex bremsstrahlung spectra typical of very intense pulsed power x-ray generators. The Monte Carlo codes TIGER and TIGERP can calculate the net photon-induced electron emission but accurate results may require that statistical error be minimized. CEPXS/ONETRAN is a new deterministic coupled electron/photon transport code that is faster than Monte Carlo and is not subject to statistical error. The comparison of net yields is a sensitive test of the relative accuracy and efficiency of these various codes. The authors find that all of the codes substantially agree with the experiments for the forward net yields. However, for reverse net yields from high-Z materials, the codes overpredict relative to measurements.

Ballard, W.P.; Lorence, L.J. Jr.; Snowden, D.P.; Van Lint, V.A.J.; Beale, E.S.

1987-12-01

209

Fluorescence excitation-emission matrix spectra coupled with parallel factor and regional integration analysis to characterize organic matter humification.  

PubMed

The present several humification indexes cannot provide the whole fluorescence information on organic matter composition and the evaluation results from them are inconsistent sometimes. In this study, fluorescence excitation-emission matrix spectra coupled with parallel factor analysis and fluorescence regional integration analysis were utilized to investigate organic matter humification, and the projection pursuit cluster (PPC) model was applied to form a suitable index for overcoming the difficulties in multi-index evaluation. The result showed that the ratio between the volume of humic- and fulvic-like fluorescence region and the volume of protein-like fluorescence region not only revealed the heterogeneity of organic matter, but also provided more accurate information on organic matter humification. In addition, the results showed that the PPC model could be used to characterize integrally the humification, and the projected characteristic value calculated from the PPC model could be used as the integrated humification evaluation index. PMID:23706894

He, Xiao-Song; Xi, Bei-Dou; Li, Xiang; Pan, Hong-Wei; An, Da; Bai, Shuo-Guo; Li, Dan; Cui, Dong-Yu

2013-05-21

210

Fourier Transform Emission Spectra of the (000)-(000) Band of the ?4051.6 Band of C3  

NASA Astrophysics Data System (ADS)

The (000)-(000) band of the 4051.6 group (A1?u-X1?+g) of C3 was recorded in emission with a Bruker IFS 120HR Fourier transform (FT) spectrometer at the University of Waterloo. The band was excited by a microwave discharge in isopropanol (less than a few mtorr) diluted in helium (2 torr). Our new FT data provide more reliable and accurately calibrated transition wavenumbers than those from the grating spectra given by Gausset and coworkers. Analysis of our new spectrum combined with the data by McCall and coworkers confirmed that the lower J levels in the A state were strongly perturbed, as reported by Gausset and coworkers. The unidentified lines observed by McCall and coworkers could be attributed to extra transitions to an unknown perturbing state.

Tanabashi, A.; Hirao, T.; Amano, T.; Bernath, P. F.

2005-05-01

211

Modulation structures in the dynamic spectra of Jovian radio emission obtained with high time-frequency resolution  

NASA Astrophysics Data System (ADS)

Aims: The wide-band dynamic spectra of Jovian decameter emission obtained over the last decade with high-frequency and high time resolution equipment on the largest decameter band antenna array, the Ukrainian T-shape Radio telescope (UTR-2), are presented. Methods: We analyzed the data obtained with the Digital SpectroPolarimiter (DSP) and WaveForm Reciever (WFR) installed at UTR-2. The combination of the large antenna and high performance equipment gives the best sensitivity and widest band of analysis, dynamic range, time and frequency resolutions. The wavelet transform method and the Fourier technique was used for further data processing. Results: The main characteristics of already known and newly detected modulation events were investigated and specified. The new receiving-recording facilities, methodology and program of observations are described in detail.

Litvinenko, G. V.; Lecacheux, A.; Rucker, H. O.; Konovalenko, A. A.; Ryabov, B. P.; Taubenschuss, U.; Vinogradov, V. V.; Shaposhnikov, V. E.

2009-01-01

212

How Aggregation and Conformational Scrambling of Unfolded States Govern Fluorescence Emission Spectra  

PubMed Central

In a case study on five homologous ?-amylases we analyzed the properties of unfolded states as obtained from treatments with GndHCl and with elevated temperatures. In particular the wavelength of the tryptophan fluorescence emission peak (?max) is a valuable parameter to characterize properties of the unfolded state. In all cases with a typical red shift of the emission spectrum occurring during structural unfolding we observed a larger magnitude of this shift for GndHCl-induced unfolding as compared to thermal unfolding. Although a quantitative relation between aggregation and reduction of the unfolding induced red shifts cannot be given, our data indicate that protein aggregation contributes significantly to smaller magnitudes of red shifts as observed during thermal unfolding. In addition, other properties of the unfolded states, most probable structural compactness or simply differences in the conformational scrambling, also affect the magnitude of red shifts. For the irreversible unfolding ?-amylases studied here, transition temperatures and magnitudes of red shifts are strongly depending on heating rates. Lower protein concentrations and smaller heating rates lead to larger red shifts upon thermal unfolding, indicating that under these conditions the protein aggregation is less pronounced.

Duy, C.; Fitter, J.

2006-01-01

213

Interferences in electron emission spectra for hydrogen cation impact on hydrogen  

NASA Astrophysics Data System (ADS)

Interference effects associated with the coherent emission of an electron from the identical atomic centers of H2 have been investigated. The interferences are manifested as oscillations in the measured electron yield as a function of the electron energy. This work, conducted at Western Michigan University using the tandem Van de Graaff accelerator, focuses on the ionization of H2 by 1--5 MeV H+ impact. The primary interference phenomenon is analogous to Young-type interferences caused by the passage of light through a pair of closely spaced slits. The observed structures exhibit variations in the oscillation frequency with electron ejection angle and projectile velocity in general agreement with predictions of the Born approximation. Secondary oscillations superimposed on the primary structures and attributed to additional scattering within the molecule have also been observed, but these oscillations have no analogy in Young's experiment. These secondary structures show only slight variations in frequency with changing electron ejection angle and no apparent dependence on the projectile velocity. Additionally, the present results indicate the existence of still higher frequency oscillations, about twenty times those of the primary structures, superimposed on the secondary oscillations. A tentative explanation for these high-frequency oscillations is given in terms of coherent electron emission from the transient molecule formed by the incoming H+ ion and one of the H 2 target centers.

Hossain, Sabbir

214

Using violet laser-induced chlorophyll fluorescence emission spectra for crop yield assessment of cowpea (Vigna unguiculata (L) Walp) varieties  

NASA Astrophysics Data System (ADS)

The use of violet laser-induced chlorophyll fluorescence (LICF) emission spectra to monitor the growth of five varieties of cowpea in the University of Cape Coast Botanical Garden is presented. Radiation from a continuous-wave violet laser diode emitting at 396 nm through a fibre is closely incident on in vivo leaves of cowpea to excite chlorophyll fluorescence, which is detected by an integrated spectrometer with CCD readout. The chlorophyll fluorescence spectra with peaks at 683 and 731 nm were used for growth monitoring of the cowpea plants over three weeks and analysed using Gaussian spectral functions with curve fitted parameters to determine the peak positions, area under the spectral curve and the intensity ratio F683/F731. The variation in the intensity ratio of the chlorophyll bands showed sensitive changes indicating the photosynthetic activity of the cowpea varieties. A discussion of the fluorescence result as compared to conventional assessment is presented with regard to discrimination between the cowpea varieties in terms of crop yield performance.

Anderson, Benjamin; Buah-Bassuah, Paul K.; Tetteh, Jonathan P.

2004-07-01

215

Seasonal variations of Saturn's auroral acceleration region deduced from spectra of auroral radio emissions  

NASA Astrophysics Data System (ADS)

Multi-instrumental surveys of Saturn's magnetosphere by Cassini have indicated that auroral radio emissions (Saturnian Kilometric Radiation, SKR), aurorae at UV and IR wavelengths and Energetic Neutral Atoms (ENA) from the inner magnetosphere exhibit periodic behavior at around Saturn's rotational period with the north-south asymmetry and seasonal variations [e.g., Gurnett et al., 2010; Mitchell et al., 2009; Nichols et al., 2010]. These rotationally periodic phenomena are suggestive of distinct magnetosphere-ionosphere coupling current systems, rotating at different periods in the northern and southern hemispheres [e.g., Andrews et al., 2010]. These phenomena suggest that the magnetosphere-ionosphere coupling process and associated energy dissipation process (aurora & SKR) are dynamically dependent on both magnetospheric rotations and long-term conditions of the magnetosphere/ionosphere.

Kimura, T.; Lamy, L.; Tao, C.; Badman, S. V.; Cecconi, B.; Zarka, P.; Morioka, A.; Miyoshi, Y.; Kasaba, Y.; Maruno, D.; Fujimoto, M.

2012-09-01

216

Broadband spectra of seismic survey air-gun emissions, with reference to dolphin auditory thresholds.  

PubMed

Acoustic emissions from a 2120 cubic in air-gun array were recorded through a towed hydrophone assembly during an oil industry 2-D seismic survey off the West Wales Coast of the British Isles. Recorded seismic pulses were sampled, calibrated, and analyzed post-survey to investigate power levels of the pulses in the band 200 Hz-22 kHz at 750-m, 1-km, 2.2-km, and 8-km range from source. At 750-m range from source, seismic pulse power at the 200-Hz end of the spectrum was 140 dB re: 1 microPa2/Hz, and at the 20-kHz end of the spectrum seismic pulse power was 90 dB re: 1 microPa2/Hz. Although the background noise levels of the seismic recordings were far in excess of ambient, due to the proximity of engine, propeller, and flow sources of the ship towing the hydrophone, seismic power dominated the entire recorded bandwidth of 200 Hz-22 kHz at ranges of up to 2 km from the air-gun source. Even at 8-km range seismic power was still clearly in excess of the high background noise levels up to 8 kHz. Acoustic observations of common dolphins during preceding seismic surveys suggest that these animals avoided the immediate vicinity of the air-gun array while firing was in progress, i.e., localized disturbance occurred during seismic surveying. Although a general pattern of localized disturbance is suggested, one specific observation revealed that common dolphins were able to tolerate the seismic pulses at 1-km range from the air-gun array. Given the high broadband seismic pulse power levels across the entire recorded bandwidth, and known auditory thresholds for several dolphin species, we consider such seismic emissions to be clearly audible to dolphins across a bandwidth of tens on kilohertz, and at least out to 8-km range. PMID:9566337

Goold, J C; Fish, P J

1998-04-01

217

THE LOCAL DUST FOREGROUNDS IN THE MICROWAVE SKY. I. THERMAL EMISSION SPECTRA  

SciTech Connect

Analyses of the cosmic microwave background (CMB) radiation maps made by the Wilkinson Microwave Anisotropy Probe (WMAP) have revealed anomalies not predicted by the standard inflationary cosmology. In particular, the power of the quadrupole moment of the CMB fluctuations is remarkably low, and the quadrupole and octopole moments are aligned mutually and with the geometry of the solar system. It has been suggested in the literature that microwave sky pollution by an unidentified dust cloud in the vicinity of the solar system may be the cause for these anomalies. In this paper, we simulate the thermal emission by clouds of spherical homogeneous particles of several materials. Spectral constraints from the WMAP multi-wavelength data and earlier infrared observations on the hypothetical dust cloud are used to determine the dust cloud's physical characteristics. In order for its emissivity to demonstrate a flat, CMB-like wavelength dependence over the WMAP wavelengths (3 through 14 mm), and to be invisible in the infrared light, its particles must be macroscopic. Silicate spheres of several millimeters in size and carbonaceous particles an order of magnitude smaller will suffice. According to our estimates of the abundance of such particles in the zodiacal cloud and trans-Neptunian belt, yielding the optical depths of the order of 10{sup -7} for each cloud, the solar system dust can well contribute 10 muK (within an order of magnitude) in the microwaves. This is not only intriguingly close to the magnitude of the anomalies (about 30 muK), but also alarmingly above the presently believed magnitude of systematic biases of the WMAP results (below 5 muK) and, to an even greater degree, of the future missions with higher sensitivities, e.g., Planck.

Dikarev, Valeri; Preuss, Oliver; Solanki, Sami; Krueger, Harald [Max-Planck-Institut fuer Sonnensystemforschung, 37191 Katlenburg-Lindau (Germany); Krivov, Alexander [Friedrich-Schiller Universitaet Jena (Germany)

2009-11-01

218

Improved fluorescence excitation-emission matrix regional integration to quantify spectra for fluorescent dissolved organic matter.  

PubMed

The purpose of this short communication is to demonstrate the importance of numerical analysis and wavelength increment selection when characterizing fluorescent dissolved organic matter (FDOM) using fluorescence excitation-emission matrix (EEM) regional integration. A variety of water samples, representing a landscape gradient and different types of FDOM, were analyzed for their percentage distribution of five operationally defined FDOM fractions (aromatic protein I, aromatic protein II, fulvic acid-like, soluble microbial byproduct-like, and humic acid-like) using three numerical methods in integrating volume under the surface of the fluorescence EEMs: Riemann summation, composite trapezoidal rule, and composite Simpson's rule. The influence of wavelength increment was also examined for the precision of the percentage distribution of each fraction. Our results show that the FDOM fraction estimated by Riemann summation with a 10- or 5-nm excitation wavelength can cause >40% or >5% errors, respectively, when compared with the best estimated values obtained by averaging results from composite trapezoidal rule and composite Simpson's rule with 1-nm excitation wavelength at the same emission increment. Also, our experiments show that fluorescence matrix regional integration could underestimate the two aromatic protein fractions but could overestimate the soluble microbial byproduct-like and humic acid-like fractions if improper increment and integral methods are used. The error can be reduced if a smaller wavelength increment is used. The smallest increment in a spectrofluorometer and composite Simpson's rule should be used for scanning fluorescence EEMs and calculating the percentage distribution of each FDOM fraction. Alternatively, 5-nm wavelength increments with composite Simpson's rule could be cost effective, and the error of each FDOM fraction commonly falls within 5% compared with those estimated by 1-nm increments. PMID:23673961

Zhou, Jie; Wang, Jun-Jian; Baudon, Antoine; Chow, Alex T

219

Phosphorus K ? X-Ray Emission Spectra and Valence-Band Structures of Transition-Metal Phosphides and GaAs 1-xPx  

NASA Astrophysics Data System (ADS)

The P K? emission spectra in fluorescence from ZrP, NbP, MoP,HfP, TaP, WP, AgP2, CdP2, Mn3P2, Cd3P2 and GaAs1-xPxfor 0.2 ? x ? 1 are measured with a high-resolutiontwo-crystal vacuum spectrometer equipped with Ge(111) crystals. Theinfluence of metal atoms appears distinctly in the P K?emission spectra of transition-metal phosphides. The effect ofarsenic atoms appears slightly in the P K? emission spectraof GaAs1-xPx. The P K? emission spectra of AgP2,CdP2, Cd3P2 and GaAs0.6 P0.4 are compared withavailable P L2,3 emission and XPS valence-band spectra ona common energy scale. It is shown that the P 3p electronsinteract fairly with the metal d electrons in the upper partof the valence band for MP ( M = Zr, Nb, Mo, Hf, Ta, W) and Mn3P2;considerable p-d, s mixing occurs in the middle part for AgP2and in the lower part for CdP2 and Cd3P2; and the Ga 3dstates mix fairly with the P 3s states in GaAs0.6P0.4.

Sugiura, Chikara

1996-07-01

220

Spontaneous emission spectra and quantum light-matter interactions from a strongly coupled quantum dot metal-nanoparticle system  

NASA Astrophysics Data System (ADS)

We investigate the quantum optical properties of a quantum-dot dipole emitter coupled to a finite-size metal nanoparticle using a photon Green-function technique that rigorously quantizes the electromagnetic fields. We first obtain pronounced Purcell factors and photonic Lamb shifts for both a 7- and 20-nm-radius metal nanoparticle, without adopting a dipole approximation. We then consider a quantum-dot photon emitter positioned sufficiently near the metal nanoparticle so that the strong-coupling regime is possible. Accounting for nondipole interactions, quenching, and photon transport from the dot to the detector, we demonstrate that the strong-coupling regime should be observable in the far-field spontaneous emission spectrum, even at room temperature. The vacuum-induced emission spectra show that the usual vacuum Rabi doublet becomes a rich spectral triplet or quartet with two of the four peaks anticrossing, which survives in spite of significant nonradiative decays. We discuss the emitted light spectrum and the effects of quenching for two different dipole polarizations.

van Vlack, C.; Kristensen, Philip Trst; Hughes, S.

2012-02-01

221

Stratospheric minor constituent distributions from far-infrared thermal emission spectra  

SciTech Connect

We retrieve mixing ratio profiles of O[sub 3], H[sub 2][sup 16], H[sub 2][sup 17]O,H[sub 2][sup 18]O, HF, and HCl from far-infrared thermal emission observations of the limb in the 80-220 cm[sup [minus]1] spectral region. The observations were made with a balloon-borne Fourier transform spectrometer as a part of the 1983 Balloon Intercomparison Campaign (BIC-2). A subset of the data was analyzed previously using the method in the work of Throb et at [1982, 1991]; in the present paper we use an alternative method of calibration and analysis, given by Abbes et al. [1985]. The retrieved constituent profiles are compared with the measurements made with other instruments on the BIC-2 flights. The results for the concentrations of H[sup 2][sup 17]O and H[sub 2][sup 18]O obtained in this study indicate no isotopic enhancement or depletion with a standard deviation of about 20%. 34 refs., 15 figs., 1 tab.

Abbas, M.M. (NASA Marshall Space Flight Center, Huntsville, AL (United States)); Traub, W.A. (Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States))

1992-11-20

222

Retrieval of stratospheric O3, HNO3, and ClONO2 profiles from 1992 MIPAS-B limb emission spectra: method, results, and error analysis  

Microsoft Academic Search

Within the framework of the European Arctic Stratospheric Ozone Experiment, two flights of the balloon-borne MIPAS-B limb emission spectrometer were performed in the Arctic stratosphere from Kiruna, northern Sweden. During the early hours of January 13 and the night from March 14 to March 15, 1992, several limb sequences of infrared spectra were recorded which have permitted the retrieval of

T. von Clarmann; H. Fischer; F. Friedl-Vallon; A. Linden; H. Oelhaf; C. Piesch; M. Seefeldner; W. Vlker

1993-01-01

223

Global peroxyacetyl nitrate (PAN) retrieval in the upper troposphere from limb emission spectra of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS)  

Microsoft Academic Search

We use limb emission spectra of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) onboard the ENVIronmental SATellite (ENVISAT) to derive the first global distribution of peroxyacetyl nitrate (PAN) in the upper troposphere. PAN is generated in tropospheric air masses polluted by fuel combustion or biomass burning and acts as a reservoir and carrier of NOx in the cold free

N. Glatthor; T. von Clarmann; H. Fischer; B. Funke; U. Grabowski; M. Hpfner; S. Kellmann; M. Kiefer; A. Linden; M. Milz; T. Steck; G. P. Stiller

2007-01-01

224

Emission Line Spectra from Fe VII to XVI in the Soft X-ray and Extreme Ultraviolet  

NASA Astrophysics Data System (ADS)

Stellar coronae are rich emitters of iron radiation in the soft x-ray and EUV. This spectral region has been opened up first by the EUV Explorer and now by the Chandra X-ray Observatory for detailed observations with high resolution. Lines in this region are a valuable diagnostic tool for temperature and density, but accurate analysis and interpretation requires accurate spectral models and data. We have shown in previous laboratory measurements that the line lists available for the low charge states of iron, especially Fe VII through Fe XIII are strikingly incomplete. Many of the lines left out in the line lists are weak, but because there are many of them, a substantial amount of spectral flux (more than 50%) is missing. Incomplete accounting of these lines can have marked consequences when modeling the coronae of cool stars, such as ? Cen, both by underestimating the flux of the lowest iron charge states and by incorrect assignments of the base level of those strong lines that sit on top of the flux caused by many unresolved weak lines. We are addressing this problem by using the unique spectroscopic abilities of the Lawrence Livermore Electron Beam Ion Trap to compile a catalogue of the relevant line emission in the soft x-ray and EUV region. As part of this catalogue we present here spectra and line lists for Fe VII - Fe XVI between 50-140 . Our line lists include wavelengths and line intensities that allow us to estimate the contributions from unresolved lines relative to those of known lines from the same charge state. We also compare these line lists and spectra with the MeKa and CHIANTI models and HULLAC calculations.

Lepson, J. K.; Beiersdorfer, P.; Brown, G. V.; Kahn, S. M.; Liedahl, D. A.; Utter, S. B.

2000-10-01

225

Determination of the texture of arrays of aligned carbon nanotubes from the angular dependence of the X-ray emission and X-ray absorption spectra  

SciTech Connect

The properties of materials containing carbon nanotubes depend on the degree of alignment and the internal structure of nanotubes. It is shown that the degree of misorientation of carbon nanotubes in samples can be evaluated from the measurements of the angular dependences of the carbon X-ray emission and carbon X-ray absorption spectra. The CK{sub {alpha}} emission and CK X-ray absorption spectra of the array of multiwalled carbon nanotubes synthesized by catalytic thermolysis of a mixture of fullerene and ferrocene are measured. A comparison of the calculated model dependences of the relative intensities of the {pi} and {sigma} bands in the spectra with the experimental results makes it possible to evaluate the degree of misorientation of nanotubes in the sample and their internal texture.

Okotrub, A. V., E-mail: spectrum@che.nsk.su; Belavin, V. V.; Bulusheva, L. G.; Gusel'nikov, A. V.; Kudashov, A. G. [Russian Academy of Sciences, Nikolaev Institute of Inorganic Chemistry, Siberian Branch (Russian Federation); Vyalikh, D. V.; Molodtsov, S. L. [Dresden University of Technology, Institute of Solid State Physics (Germany)

2008-09-15

226

Relativistic configuration interaction calculations for the K{alpha} and K{beta} X-ray satellites of iron  

SciTech Connect

Multi-configuration Dirac-Fock and relativistic configuration interaction calculations with the Breit interaction, quantum electrodynamics, and finite nuclear mass corrections were carried out in the extended optimal level scheme for the transition wavelengths, electric dipole transition rates, and oscillator strengths of the K{alpha} and K{beta} X-rays from Fe XVII through Fe XXV. The calculated values were compared with the available data on He-like, Li-like, Be-like, and F-like iron, and were in very good agreement. These data provide reference values for level lifetime, charge state distribution, and average charge of iron plasmas.

Hou Haijun [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, Sichuan 610065 (China)], E-mail: hhj-0514@163.com; Jiang Gang [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, Sichuan 610065 (China)], E-mail: gjiang@scu.edu.cn; Hu Feng; Hao Lianghuan [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, Sichuan 610065 (China)

2009-03-15

227

X-ray emission spectra of the plasma produced by an ultrashort laser pulse in cluster targets  

SciTech Connect

The first observation of x-ray emission spectra of multiply charged ions in the plasma produced by a 35-fs laser pulse with an intensity up to 10{sup 17} W cm{sup -2} in CO{sub 2} and Kr gas jet targets is reported. The emission in the wavelength ranges of the 1snp-1s{sup 2}(n=3-6) transitions of O VII ions and the Ly{sub {alpha}} line of O VIII ions, as well as of the (2s{sub 1/2}2p{sup 6}3p{sub 3/2}){sub 1}-2s{sup 2}2p{sup 6} {sup 1}S{sub 0} and (2s{sub 1/2}2p{sup 6}3p{sub 1/2}){sub 1}-2s{sup 2}2p{sup 6} {sup 1}S{sub 0} lines of Ne-like KrXXVII ions testifies that the highly ionised plasma is formed by collision processes in clusters. Modelling the shape of the spectral lines of oxygen ions by including the principal mechanisms of broadening and absorption in optically dense plasmas reveals that the main contribution to the time-integrated intensity is made by the plasma with the parameters N{sub e}=(2-20)x10{sup 20} cm{sup -3} and T{sub e}=100 - 115 eV. (interaction of laser radiation with matter. laser plasma)

Stenz, C; Bagnoud, V; Blasco, F; Roche, J R; Salin, F [Centre Laser Intenses et Applications, Universite Bordeaux, Talence (France); Faenov, A Ya; Skobelev, I Yu [Multicharged Ion Spectra Data Center, All-Russia Research Institute of Psysicotechnical and Radio Enginering Measurments, Mendeleevo, Moscow Region (Russian Federation); Magunov, A I [A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Pikuz, T A [N.E. Bauman Moscow State Technical University, Moscow (Russian Federation)

2000-08-31

228

Bremsstrahlung and K(alpha) fluorescence measurements for inferring conversion efficiencies into fast ignition relevant hot electrons  

SciTech Connect

The Bremsstrahlung and K-shell emission from 1 mm x 1 mm x 1 mm planar targets irradiated by a short-pulse 3 x 10{sup 18}-8 x 10{sup 19} W/cm{sup 2} laser were measured. The Bremsstrahlung was measured using a filter stack spectrometer with spectral discrimination up to 500 keV. K-shell emission was measured using a single photon counting charge coupled device (CCD). From Monte Carlo modeling of the target emission, conversion efficiencies into 1-3 MeV electrons of 3-12%, representing 20-40% total conversion efficiencies were inferred for intensities up to 8 x 10{sup 19} W/cm{sup 2}. Comparisons to scaling laws using synthetic energy spectra generated from the intensity distribution of the focal spot imply slope temperatures less than the ponderomotive potential of the laser. Resistive transport effects may result in potentials of a few hundred kV in the first few tens of microns in the target. This would lead to higher total conversion efficiencies than inferred from Monte Carlo modeling but lower conversion efficiencies into 1-3 MeV electrons.

Chen, C D; Patel, P K; Hey, D S; Mackinnon, A J; Key, M H; Akli, K U; Bartal, T; Beg, F N; Chawla, S; Chen, H; Freeman, R R; Higginson, D P; Link, A; Ma, T Y; MacPhee, A G; Stephens, R B; Van Woerkom, L D; Westover, B; Porkolab, M

2009-07-24

229

Atomic Spectra  

NSDL National Science Digital Library

In this Flash animation the user can view the atomic emission spectra (400-700nm) of eight different elements. A dragable marker allows the user to approximate the wavelength of the various spectral lines. The effect of resolution can be examined in the sodium spectrum in the region 550-600nm.

230

Absolute Time-Resolved Emission of Non-LTE L-Shell Spectra from Ti-Doped Aerogels  

SciTech Connect

Outstanding discrepancies between data and calculations of laser-produced plasmas in recombination have been observed since the 1980s. Although improvements in hydrodynamic modeling may reduce the discrepancies, there are indications that non-LTE atomic kinetics may be the dominant cause. Experiments to investigate non-LTE effects were recently performed at the NIKE KrF laser on low-density Ti-doped aerogels. The laser irradiated a 2 mm diameter, cylindrical sample of various lengths with a 4-ns square pulse to create a volumetrically heated plasma. Ti L-shell spectra spanning a range of 0.47-3 keV were obtained with a transmission grating coupled to Si photodiodes. The diagnostic can be configured to provide 1-dimensional spatial resolution at a single photon energy, or 18 discrete energies with a resolving power, {gamma}/{delta}{gamma} of 3-20. The data are examined and compared to calculations to develop absolute emission measurements that can provide new tests of the non-LTE physics.

Back,C.; Feldman, U.; Weaver, J.; Seely, J.; Constantin, C.; Holland, G.; Lee, R.; Chung, H.; Scott, H.

2006-01-01

231

Absolute, time-resolved emission of non-LTE L-shell spectra from Ti-doped aerogels  

NASA Astrophysics Data System (ADS)

Outstanding discrepancies between data and calculations of laser-produced plasmas in recombination have been observed since the 1980s. Although improvements in hydrodynamic modeling may reduce the discrepancies, there are indications that non-LTE atomic kinetics may be the dominant cause. Experiments to investigate non-LTE effects were recently performed at the NIKE KrF laser on low-density Ti-doped aerogels. The laser irradiated a 2 mm diameter, cylindrical sample of various lengths with a 4-ns square pulse to create a volumetrically heated plasma. Ti L-shell spectra spanning a range of 0.47 3 keV were obtained with a transmission grating coupled to Si photodiodes. The diagnostic can be configured to provide 1-dimensional spatial resolution at a single photon energy, or 18 discrete energies with a resolving power, ?/?? of 3 20. The data are examined and compared to calculations to develop absolute emission measurements that can provide new tests of the non-LTE physics.

Back, C. A.; Feldman, U.; Weaver, J. L.; Seely, J. F.; Constantin, C.; Holland, G.; Lee, R. W.; Chung, H.-K.; Scott, H. A.

2006-05-01

232

Clouds in the atmospheres of extrasolar planets. II. Thermal emission spectra of Earth-like planets influenced by low and high-level clouds  

NASA Astrophysics Data System (ADS)

Aims: We study the impact of multi-layered clouds (low-level water and high-level ice clouds) on the thermal emission spectra of Earth-like planets orbiting different types of stars. Clouds have an important influence on such planetary emission spectra due to their wavelength dependent absorption and scattering properties. We also investigate the influence of clouds on the ability to derive information about planetary surface temperatures from low-resolution spectra. Methods: We use a previously developed parametric cloud model based on observations in the Earth's atmosphere, coupled to a one-dimensional radiative-convective steady state climate model. This model is applied here to study the effect of clouds on the thermal emission spectra of Earth-like extrasolar planets in dependence of the type of central star. Results: The presence of clouds lead in general to a decrease of the planetary IR spectrum associated with the dampening of spectral absorption features such as the 9.6 ?m absorption band of O3 for example. This dampening is not limited to absorption features originating below the cloud layers but was also found for features forming above the clouds. When only single cloud layers are considered, both cloud types exhibit basically the same effects on the spectrum but the underlying physical processes are clearly different. For model scenarios where multi-layered clouds have been considered with coverages which yield mean Earth surface temperatures, the low-level clouds have only a small influence on the thermal emission spectra. In these cases the major differences are caused by high-level ice clouds. The largest effect was found for a planet orbiting the F-type star, where no absorption features can be distinguished in the low-resolution emission spectrum for high cloud coverages. However, for most central stars, planetary atmospheric absorption bands are present even at high cloud coverages. Clouds also affect the derivation of surface temperatures from low-resolution spectra when fitting black-body radiation curves to the spectral shape of the IR emission spectra. With increasing amount of high-level clouds the derived temperatures increasingly under-estimate the real planetary surface temperatures. Consequently, clouds can alter significantly the measured apparent temperature of a planet as well as the detectability of the characteristic spectral signatures in the infrared. Therefore, planets with observationally derived somewhat lower surface temperatures should not be discarded too quickly from the list of potential habitable planets before further investigations on the presence of clouds have been made.

Kitzmann, D.; Patzer, A. B. C.; von Paris, P.; Godolt, M.; Rauer, H.

2011-07-01

233

Temperature sensitivity of Cu K(alpha) imaging efficiency using a spherical Bragg reflecting crystal  

SciTech Connect

The Vulcan laser facility at the Rutherford Appleton Laboratory was used to study the interaction of a 75 J 10 ps, high intensity laser beam with low-mass solid, Cu targets. Two instruments were fielded as diagnostics of the Cu K-shell emission from the targets: A single photon counting CCD spectrometer provided the absolute K{sub {alpha}} yield and a spherically bent Bragg crystal recorded 2D monochromatic images with a spatial resolution of 10 {micro}m. Due to the shifting and broadening of the K{sub {alpha}} spectral lines with increasing temperature, there is a temperature dependence of the crystal collection efficiency. This provides a temperature diagnostic when cross calibrated against a single hit CCD spectrometer, and it affects measurements of the spatial pattern of electron transport. The experimental data showing changing collection efficiency are presented. The results are discussed in light of modeling of the temperature-dependent spectrum of Cu K-shell emission.

Akli, K U; Key, M H; Chung, H K; Hansen, S B; Freeman, R R; Chen, M H; Gregori, G; Hatchett, S; Hey, D; Izumi, N; King, J A; Kuba, J; Norreys, P; Mackinnon, A J; Murphy, C D; Snavely, R; Stepehens, R; Stoeckel, C; Theobald, W; Zhang, B

2006-08-07

234

State-of-the art comparability of corrected emission spectra. 2. Field laboratory assessment of calibration performance using spectral fluorescence standards.  

PubMed

In the second part of this two-part series on the state-of-the-art comparability of corrected emission spectra, we have extended this assessment to the broader community of fluorescence spectroscopists by involving 12 field laboratories that were randomly selected on the basis of their fluorescence measuring equipment. These laboratories performed a reference material (RM)-based fluorometer calibration with commercially available spectral fluorescence standards following a standard operating procedure that involved routine measurement conditions and the data evaluation software LINKCORR developed and provided by the Federal Institute for Materials Research and Testing (BAM). This instrument-specific emission correction curve was subsequently used for the determination of the corrected emission spectra of three test dyes, X, QS, and Y, revealing an average accuracy of 6.8% for the corrected emission spectra. This compares well with the relative standard uncertainties of 4.2% for physical standard-based spectral corrections demonstrated in the first part of this study (previous paper in this issue) involving an international group of four expert laboratories. The excellent comparability of the measurements of the field laboratories also demonstrates the effectiveness of RM-based correction procedures. PMID:22376144

Resch-Genger, Ute; Bremser, Wolfram; Pfeifer, Dietmar; Spieles, Monika; Hoffmann, Angelika; DeRose, Paul C; Zwinkels, Joanne C; Gauthier, Franois; Ebert, Bernd; Taubert, R Dieter; Voigt, Jan; Hollandt, Jrg; Macdonald, Rainer

2012-04-16

235

The 21 micron emission band in the IRAS/LRS spectra of H II regions - Evidence of iron oxide in the interstellar medium  

NASA Astrophysics Data System (ADS)

The 21-micron emission line, recently found in four post-AGB stars by Kwok et al. (1989) is found to be ubiquitous in the IRAS/LRS midinfrared spectra of H II regions, accounting for about 20 percent of the total IRAS luminosity of these regions. Based on laboratory infrared absorption spectra, it is proposed that the carriers are iron oxides, such as maghemite (gamma-Fe2O3) or magnetite (Fe3O4). The magnetite found in the Orgueil meteorite provides the best spectroscopic match. The results support the Davis-Greenstein mechanism of the interstellar polarization.

Cox, P.

1990-09-01

236

Molecular dynamics simulations of fine structure in oxygen K-edge x-ray emission spectra of liquid water and ice  

SciTech Connect

X-ray emission (XE) spectroscopy has recently been taken as evidence for specific molecular structures in hydrogen bonded liquids. Experimentally derived and contradicting interpretations of the fine structure in the XE spectra of liquid water have been proposed in the literature. Here it is shown that all features of the XE spectra of liquid water can be explained based on ab initio molecular dynamics simulations by including core-hole excited-state dynamics. Future experiments are proposed which could discriminate between existing interpretations without relying on theory.

Odelius, Michael [FYSIKUM, Stockholm University, Albanova, S-106 91 Stockholm (Sweden)

2009-04-01

237

Physical properties, transmission and emission spectra of the WASP-19 planetary system from multi-colour photometry  

NASA Astrophysics Data System (ADS)

We present new ground-based, multi-colour, broad-band photometric measurements of the physical parameters, transmission and emission spectra of the transiting extrasolar planet WASP-19b. The measurements are based on observations of eight transits and four occultations through a Gunn i filter using the 1.54-m Danish Telescope, 14 transits through an Rc filter at the Perth Exoplanet Survey Telescope (PEST) observatory and one transit observed simultaneously through four optical (Sloan g', r', i', z') and three near-infrared (J, H, K) filters, using the Gamma Ray Burst Optical and Near-Infrared Detector (GROND) instrument on the MPG/ESO 2.2-m telescope. The GROND optical light curves have a point-to-point scatter around the best-fitting model between 0.52 and 0.65 mmag rms. We use these new data to measure refined physical parameters for the system. We find the planet to be more bloated (Rb = 1.410 0.017RJup; Mb = 1.139 0.030MJup) and the system to be twice as old as initially thought. We also used published and archived data sets to study the transit timings, which do not depart from a linear ephemeris. We detected an anomaly in the GROND transit light curve which is compatible with a spot on the photosphere of the parent star. The starspot position, size, spot contrast and temperature were established. Using our new and published measurements, we assembled the planet's transmission spectrum over the 370-2350 nm wavelength range and its emission spectrum over the 750-8000 nm range. By comparing these data to theoretical models we investigated the theoretically predicted variation of the apparent radius of WASP-19b as a function of wavelength and studied the composition and thermal structure of its atmosphere. We conclude that: (i) there is no evidence for strong optical absorbers at low pressure, supporting the common idea that the planet's atmosphere lacks a dayside inversion; (ii) the temperature of the planet is not homogenized, because the high warming of its dayside causes the planet to be more efficient in re-radiating than redistributing energy to the night side; (iii) the planet seems to be outside of any current classification scheme.

Mancini, L.; Ciceri, S.; Chen, G.; Tregloan-Reed, J.; Fortney, J. J.; Southworth, J.; Tan, T. G.; Burgdorf, M.; Calchi Novati, S.; Dominik, M.; Fang, X.-S.; Finet, F.; Gerner, T.; Hardis, S.; Hinse, T. C.; Jrgensen, U. G.; Liebig, C.; Nikolov, N.; Ricci, D.; Schfer, S.; Schnebeck, F.; Skottfelt, J.; Wertz, O.; Alsubai, K. A.; Bozza, V.; Browne, P.; Dodds, P.; Gu, S.-H.; Harpse, K.; Henning, Th.; Hundertmark, M.; Jessen-Hansen, J.; Kains, N.; Kerins, E.; Kjeldsen, H.; Lund, M. N.; Lundkvist, M.; Madhusudhan, N.; Mathiasen, M.; Penny, M. T.; Prof, S.; Rahvar, S.; Sahu, K.; Scarpetta, G.; Snodgrass, C.; Surdej, J.

2013-11-01

238

Physical properties, transmission and emission spectra of the WASP-19 planetary system from multi-colour photometry  

NASA Astrophysics Data System (ADS)

We present new ground-based, multi-colour, broad-band photometric measurements of the physical parameters, transmission and emission spectra of the transiting extrasolar planet WASP-19b. The measurements are based on observations of eight transits and four occultations through a Gunn i filter using the 1.54-m Danish Telescope, 14 transits through an Rc filter at the Perth Exoplanet Survey Telescope (PEST) observatory and one transit observed simultaneously through four optical (Sloan g', r', i', z') and three near-infrared (J, H, K) filters, using the Gamma Ray Burst Optical and Near-Infrared Detector (GROND) instrument on the MPG/ESO 2.2-m telescope. The GROND optical light curves have a point-to-point scatter around the best-fitting model between 0.52 and 0.65 mmag rms. We use these new data to measure refined physical parameters for the system. We find the planet to be more bloated (Rb = 1.410 0.017RJup; Mb = 1.139 0.030MJup) and the system to be twice as old as initially thought. We also used published and archived data sets to study the transit timings, which do not depart from a linear ephemeris. We detected an anomaly in the GROND transit light curve which is compatible with a spot on the photosphere of the parent star. The starspot position, size, spot contrast and temperature were established. Using our new and published measurements, we assembled the planet's transmission spectrum over the 370-2350 nm wavelength range and its emission spectrum over the 750-8000 nm range. By comparing these data to theoretical models we investigated the theoretically predicted variation of the apparent radius of WASP-19b as a function of wavelength and studied the composition and thermal structure of its atmosphere. We conclude that: (i) there is no evidence for strong optical absorbers at low pressure, supporting the common idea that the planet's atmosphere lacks a dayside inversion; (ii) the temperature of the planet is not homogenized, because the high warming of its dayside causes the planet to be more efficient in re-radiating than redistributing energy to the night side; (iii) the planet seems to be outside of any current classification scheme.

Mancini, L.; Ciceri, S.; Chen, G.; Tregloan-Reed, J.; Fortney, J. J.; Southworth, J.; Tan, T. G.; Burgdorf, M.; Calchi Novati, S.; Dominik, M.; Fang, X.-S.; Finet, F.; Gerner, T.; Hardis, S.; Hinse, T. C.; Jrgensen, U. G.; Liebig, C.; Nikolov, N.; Ricci, D.; Schfer, S.; Schnebeck, F.; Skottfelt, J.; Wertz, O.; Alsubai, K. A.; Bozza, V.; Browne, P.; Dodds, P.; Gu, S.-H.; Harpse, K.; Henning, Th.; Hundertmark, M.; Jessen-Hansen, J.; Kains, N.; Kerins, E.; Kjeldsen, H.; Lund, M. N.; Lundkvist, M.; Madhusudhan, N.; Mathiasen, M.; Penny, M. T.; Prof, S.; Rahvar, S.; Sahu, K.; Scarpetta, G.; Snodgrass, C.; Surdej, J.

2013-10-01

239

Time-resolved emission spectra of 4-dimethylamino-4'-cyano-stilbene and resveratrol in high viscosity solvents and silica matrices.  

PubMed

Time-resolved emission spectra of 4-dimethylamino-4'-cyano-stilbene (DMACS) and 3,5,4'-trihydroxy-stilbene (resveratrol, RSV) in propylene glycol and in rigid silica xerogel matrix at 23C were studied. For the polar molecule DMACS in propylene glycol, a 66nm shift of maximum wavelength of emission spectra was observed within 1ns after excitation, and most of the shift occurred during the first 200ps. For resveratrol in propylene glycol no such a shift was observed. The rigid silica environment eliminates some deactivation pathways and stabilizes spectroscopic properties of both molecules. Spectral properties of nonpolar and high dipole moment molecules in viscous liquids and rigid environments are compared. Results are explained on the basis of intramolecular processes and solute-solvent relaxation, as well. PMID:23832219

Borowiak, Ma?gorzata; Grobelna, Beata; Synak, Anna; Bojarski, Piotr; Kubicki, Aleksander A

2013-06-19

240

Searching double-peaked emission-line profiles in the spectra of galaxies through the symmetry of the cross-correlation function  

NASA Astrophysics Data System (ADS)

The presence of double-peaked/multi-component emission-line profiles in the spectra of galaxies is commonly identified by visual inspection. However, the identification of complex emission-line profiles by eye is unlikely for large data bases such as the Sloan Digital Sky Survey (SDSS) or the integral field spectroscopy surveys of galaxies (e.g. Calar Alto Legacy Integral Field Area Survey or The Mapping Nearby Galaxies at APO). We describe a quick method involving a cross-correlation technique for detecting the presence of complex (double-peaked or multiple components) profiles in the spectra of galaxies, deriving simultaneously a first estimation of the velocity dispersions and radial velocities of the dominant gaseous component. We illustrate the proposed procedure with the well-known complex [O III]??4959, 5007 profiles of the central region of NGC 1068.

Garca-Lorenzo, B.

2013-03-01

241

Site-selective excitation and polarized absorption and emission spectra of trivalent thulium and erbium in strontium fluorapatite  

Microsoft Academic Search

Polarized fluorescence spectra produced by site-selective excitation, and conventional polarized absorption spectra were obtained for Tm3+ and Er3+ ions individually incorporated into single crystals of strontium fluorapatite, Sr5(PO4)3F, also known as SFAP. Substitution of the trivalent rare earth ion for divalent strontium was achieved by passive charge compensation during Czochralski growth of the fluorapatite crystals. Spectra were obtained between 1780

John B. Gruber; Andrew O. Wright; Michael D. Seltzer; Bahram Zandi; Larry D. Merkle; J. Andrew Hutchinson; Clyde A. Morrison; Toomas H. Allik; Bruce H. T. Chai

1997-01-01

242

Site-selective excitation and polarized absorption and emission spectra of trivalent thulium and erbium in strontium fluorapatite  

Microsoft Academic Search

Polarized fluorescence spectra produced by site-selective excitation and conventional polarized absorption spectra were obtained for Tm{sup 3+} and Er{sup 3+} ions individually incorporated into single crystals of strontium fluorapatite, Sr(PO)F. Substitution of the trivalent rare earth ion for divalent strontium was achieved by passive charge compensation during Czochralski growth of the fluorapatite crystals. Spectra were obtained between 1780 and 345

John B. Gruber; Andrew O. Wright; Michael D. Seltzer; Bahram Zandi; Larry D. Merkle; J. Andrew Hutchinson; Clyde A. Morrison; Toomas H. Allik; Bruce H. T. Chai

1997-01-01

243

Stratospheric ClONO2 and HNO3 profiles inside the Arctic vortex from MIPAS-B limb emission spectra obtained during EASOE  

Microsoft Academic Search

Vertical profiles of ClONO2 and HNO3 inside the Arctic vortex have been retrieved from infrared limb emission spectra recorded during balloon flights on January 13 and in the night of March 14\\/15, 1992 from Esrange, Sweden (68N) as part of the European Arctic Stratospheric Ozone Experiment (EASOE). The instrumentation used was the cryogenic Michelson Interferometer for Passive Atmospheric Sounding, Balloon-borne

H. Oelhaf; T. v. Clarmann; H. Fischer; F. Friedl-Vallon; Ch. Fritzsche; A. Linden; Ch. Piesch; M. Seefeldner; W. Vlker

1994-01-01

244

INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Percolation and emission spectra of a laser plasma upon ablation of silicon and silicon-containing composites  

NASA Astrophysics Data System (ADS)

The emission spectra of plasmas produced near the surface of silicon and sulphur samples and their mixtures by nanosecond and millisecond laser pulses are studied in a broad range of pressures of buffer gases. The percolation dependences are obtained for composite SiS, SiSiO2, and SiO2S targets. It is found that experimental percolation thresholds coincide with the typical threshold for three-dimensional continual percolation.

Kask, Nikolai E.; Michurin, Sergei V.; Fedorov, Gennadii M.

2006-05-01

245

Effect of annealing treatment on K{beta}-to-K{alpha} x-ray intensity ratios of 3d transition-metal alloys  

SciTech Connect

The influence of heat annealing treatment on the K{beta}-to-K{alpha} x-ray intensity ratios of 3d transition metal was carried out by x-ray fluorescence studies of various alloy compositions. K{beta}-to-K{alpha} x-ray intensity ratios of Fe, Ni, Ti, Co, and Cu in Fe{sub x}Ni{sub 1-x}, Ti{sub x}Ni{sub 1-x}, and Co{sub x}Cu{sub 1-x} alloys unannealed and thermally annealed at different temperatures have been measured following excitation by 22.69-keV x rays from a 10-mCi {sup 109}Cd radioactive point source. The experimental data obtained after annealing treatment indicate deviations of K{beta}-to-K{alpha} x-ray intensity ratios for 3d transition metals in different alloy compositions from the corresponding ratios for unannealed samples. The present investigation makes it possible to perform reliable interpretation of experimental K{beta}-to-K{alpha} x-ray intensity ratios for various 3d transition metals in their alloys and can also provide quantitative information about the changes of the K{beta}-to-K{alpha} x-ray intensity ratios of these metals with annealing treatment in considered systems.

Han, I. [Faculty of Arts and Sciences, Department of Physics, Agri Ibrahim Cecen University, TR-04100 Agri (Turkey); Demir, L. [Faculty of Sciences, Department of Physics, Atatuerk University, TR-25240 Erzurum (Turkey)

2010-06-15

246

New Chandra observations of the jet in 3C273. 1. Softer X-ray than radio spectra and the X-ray emission mechanism  

SciTech Connect

The jet in 3C273 is a high-power quasar jet with radio, optical and X-ray emission whose size and brightness allow a detailed study of the emission processes acting in it. We present deep Chandra observations of this jet and analyze the spectral properties of the jet emission from radio through X-rays. We find that the X-ray spectra are significantly softer than the radio spectra in all regions of the bright part of the jet except for the first bright ''knot A'', ruling out a model in which the X-ray emission from the entire jet arises from beamed inverse-Compton scattering of cosmic microwave background photons in a single-zone jet flow. Within two-zone jet models, we find that a synchrotron origin for the jet's X-rays requires fewer additional assumptions than an inverse-Compton model, especially if velocity shear leads to efficient particle acceleration in jet flows.

Jester, Sebastian; /Fermilab; Harris, D.E.; /Smithsonian Astrophys. Observ.; Marshall, H.L.; /MIT, MKI; Meisenheimer, K.; /Heidelberg, Max Planck Inst. Astron.

2006-05-01

247

Extracting ion emission lines from femtosecond-laser plasma x-ray spectra heavily contaminated by spikes  

NASA Astrophysics Data System (ADS)

Nowadays charged-coupled device (CCD) detectors are widely used for the registration of multicharged ions x-ray spectra. These spectra are generated in a plasma during interaction of ultrashort, ultraintense laser pulses with solid targets. Strong parasitic radiation from the plasma affects CCD detectors and contaminates resulting spectra, so that spectral features can be completely covered by noise even during measurements with a very short accumulation time. In this work we propose a ``mean to median'' (M2M) algorithm for noise suppression in femtosecond laser plasma x-ray spectra. Series of spectra is necessary for the identification of corrupted data points by the developed method. The algorithm was tested with model spectra which reflect main features of experimental data. In practice we used it for extracting information about spectral lines of Ne-like Fe ions and He-like Al ions which allowed us to calculate plasma parameters. It is demonstrated that M2M method is able to clean spectra with more than 10% of corrupted pixels. Fluctuations in intensity of spectral lines induced by laser instability do not affect validity of the proposed method.

Gasilov, S. V.; Faenov, A. Ya.; Pikuz, T. A.; Villoresi, P.; Poletto, L.; Stagira, S.; Calegari, F.; Vozzi, C.; Nisoli, M.

2007-09-01

248

Demonstration of Successful X-ray Thomson Scattering Using Picosecond K-(alpha) X-ray Sources for the Characterization of Dense Heated Matter  

SciTech Connect

We discuss the first successful K-{alpha} x-ray Thomson scattering experiment from solid density plasmas for use as a diagnostic in determining the temperature, density, and ionization state of warm dense matter with picosecond resolution. The development of this source as a diagnostic and stringent requirements for successful K-{alpha} x-ray Thomson scattering are addressed. Data for the experimental techniques described in this paper [1] suggest the capability of single shot characterization of warm dense matter and the ability to use this scattering source at future Free Electron Lasers (FEL) where comparable scattering signal levels are predicted.

Kritcher, A; Neumayer, P; Lee, H J; Doeppner, T; Falcone, R; Glenzer, S; Morse, E C

2008-05-05

249

Role of modifier oxide in emission spectra and kinetics of Er-Ho codoped Na2SO(4)-MO-P2O5 glasses.  

PubMed

The glasses of the composition 19Na(2)SO(4)-20MO-60P(2)O(5): 1.0Ho(2)O(3)/1.0Er(2)O(3) (M=Mg, Ca, and Ba) have been synthesized. Optical absorption and fluorescence spectra (in the spectral range 350-2100 nm were studied at ambient temperature. The spectra were characterized using Judd-Ofelt theory. From the luminescence spectra, various radiative properties like transition probability A, branching ratio ? and the radiative life time ? for blue (B), green (G) and red (R) emission levels of these glasses have been evaluated. The energy transfer between the two rare earth ions (Ho(3+) and Er(3+)) in co-doped Na(2)SO(4)-MO-P(2)O(5) glass systems in the visible and NIR regions has also been investigated. Highest intensity, the highest quantum efficiency and maximum energy transfer with low phonon losses of B, G, and R lines has been observed in BaO mixed glasses. The reasons for such higher values of these parameters have been discussed in the light of varying field strengths at the rare earths ion site due to replacement of one modifier oxide with the other. The enhanced intensity of NIR emission (at 2.0 ?m) has also been discussed in terms of cross relaxation of Er(3+) ions from (4)I(13/2) level to (5)I(7) of Ho(3+) ions. PMID:22112571

Rao, P Raghava; Venkatramaiah, N; Gandhi, Y; Kumar, V Ravi; Kityk, I V; Veeraiah, N

2011-11-04

250

Control of spontaneous emission spectra and simulation of multiple spontaneously generated coherence in a four-level atomic system  

NASA Astrophysics Data System (ADS)

We investigate the fluorescence spectrum for a four-level atomic system, three levels of which are coupled with two laser fields in a ladder configuration, and the upper-most level decays to the fourth level via spontaneous emission. The results show that a few interesting phenomena such as spectral-line narrowing, spectral-line enhancement, spectral-line suppression, and spontaneous emission quenching can be realized in our system and can be manipulated via adjusting the proper parameters. It is found that, in the dressed-state picture, this system is equivalent to the system with multiple spontaneously generated coherence studied by Joshi et al. [A. Joshi, W. Yang, M. Xiao, Phys. Lett. A 325 (2004) 30].PACS42.50.Gy32.80.Qk32.50.+dKeywordsSpontaneous emission spectraMultiple spontaneously generated coherenceDressed state pictureReferencesS.Y.ZhuL.M.NarducciM.O.ScullyPhys. Rev. A5219954791S.Y.ZhuR.C.F.ChanC.P.LeePhys. Rev. A521995710S.Y.ZhuH.ChenH.HuangPhys. Rev. Lett.791997205S.JohnT.QuangPhys. Rev. Lett.7819971888P.ZhouS.SwainPhys. Rev. A551997772H.HuangS.Y.ZhuM.S.ZubairyPhys. Rev. A551997744Y.WuPhys. Rev. A612000033803Y.WuP.T.LeungPhys. Rev. A601999630Y.WuX.YangP.T.LeungOpt. Lett.241999345C.H.KeitelP.L.KnightL.M.NarducciM.O.ScullyOpt. Commun.1181995143F.GhafoorS.Y.ZhuM.S.ZubairyPhys. Rev. A622000013811E.PaspalakisC.H.KeitelP.L.KnightPhys. Rev. A5819984868E.PaspalakisP.L.KnightPhys. Rev. Lett.811998293K.T.KapaleM.O.ScullyS.Y.ZhuM.S.ZubairyPhys. Rev. A672003023804M.A.AntnO.G.CaldernF.CarreoPhys. Rev. A722005023809X.M.HuJ.S.PengJ. Phys. B: At. Mol. Opt. Phys.332000921H.LeeP.PolynkinM.O.ScullyS.Y.ZhuPhys. Rev. A5519974454S.Y.ZhuM.O.ScullyPhys. Rev. Lett.761996388P.R.BermanPhys. Rev. A5819984886P.ZhouS.SwainPhys. Rev. Lett.781997832C.H.KeitelPhys. Rev. Lett.8319991307T.HongC.CramerW.NagourneyE.N.FortsonPhys. Rev. Lett.942005050801F.GhafoorS.QamarM.S.ZubairyPhys. Rev. A652002043819M.A.G.MartinezP.R.HerczfeldC.SamuelsL.M.NarducciC.H.KeitelPhys. Rev. A5519974483G.S.AgarwalPhys. Rev. Lett.671991980A.S.ZibrovM.D.LukinD.E.NikonovL.HollbergM.O.ScullyV.L.VelichanskyH.G.RobinsonPhys. Rev. Lett.7519951499S.E.HarrisPhys. Rev. Lett.6219891033J.Y.GaoC.GuoX.Z.GuoG.X.JinQ.W.WangJ.ZhaoH.Z.ZhangY.JiangD.Z.WangD.M.JiangOpt. Commun.931992323M.O.ScullyM.FleischhauerPhys. Rev. Lett.6919921360M.FleischhauerA.B.MatskoM.O.ScullyPhys. Rev. A622000013808T.HongC.CramerW.NagourneyE.N.FortsonPhys. Rev. Lett.942005050801M.O.ScullyPhys. Rev. Lett.6719911855M.FleischhauerC.H.KeitelM.O.ScullyC.SuB.T.UlrichS.Y.ZhuPhys. Rev. A4619921468C.H.BennettD.P.DivincenzoNature4042000247D.PetrosyanY.P.MalakyanPhys. Rev. A702004023822M.PaternostroM.S.KimP.L.KnightPhys. Rev. A712005022311E.ArimondoE.WolfProgress in Optics1996ElsevierAmsterdam257G.S.AgarwalQuantum Optics1974Springer-VerlagBerlinJ.JavanainenEurophys. Lett.171992407A.FountoulakisA.F.TerzisE.PaspalakisPhys. Rev. A732006033811S.MenonG.S.AgarwalPhys. Rev. A611999013807W.HarshawardhanG.S.AgarwalPhys. Rev. A581998598O.KocharovskayaA.B.MatskoY.RostovtsevPhys. Rev. A652001013803S.MenonG.S.AgarwalPhys. Rev. A5719984014G.X.LiF.L.LiS.Y.ZhuPhys. Rev. A642001013819For early work on this subject, see alsoG.S.AgarwalPhys. Rev. Lett.8420005500J.H.WuA.J.LiY.DingY.C.ZhaoJ.Y.GaoPhys. Rev. A722005023802A.J.LiJ.Y.GaoJ.H.WuL.WangJ. Phys. B: At. Mol. Opt. Phys.3820053815J.H.LiJ.B.LiuA.X.ChenC.C.QiPhys. Rev. A742006033816A.JoshiM.XiaoEur. Phys. J. D352005547A.JoshiW.YangM.XiaoPhys. Lett. A325200430Y.WuX.YangPhys. Rev. A712005053806Y.WuX.YangPhys. Rev. A702004053818Y.WuJ.SaldanaY.ZhuPhys. Rev. A672003013811Y.WuL.WenY.ZhuOpt. Lett.282003631V.WeisskopfE.P.WignerZ. Phys.54193063S.M.BarnettP.M.RadmoreMethods in Theoretical Quantum Optics1997Oxford University PressOxfordWithout loss of generality, we have assumed that the probe field ?p and the coupling field ?c are real in this part.

Li, Jia-Hua; Chen, Ai-Xi; Liu, Ji-Bing; Yang, Xiaoxue

2007-10-01

251

Study on the impact of polar stratospheric clouds on high resolution mid-IR limb emission spectra  

Microsoft Academic Search

Satellite observations of polar stratospheric clouds (PSCs) in the mid-infrared by high resolution limb emission spectrometers like the Michelson Interferometer for Passive Atmospheric Sounding have been simulated. For particles with radius >1?m the scattered tropospheric radiance accounts for a significant part of the continuum signal and leads to absorption line features overlaid over the stratospheric emission spectrum. The scattered radiance

Michael Hpfner

2004-01-01

252

Simulation of the A-X and B-X transition emission spectra of the InBr molecule for diagnostics in low-pressure plasmas  

NASA Astrophysics Data System (ADS)

Inductively coupled low-pressure discharges containing InBr have been investigated spectroscopically. In order to obtain plasma parameters such as the vibrational and rotational temperature of the InBr molecule, the emission spectra of the A\\,^3\\!\\Pi_{0^+}\\rightarrow X\\,^1\\!\\Sigma_{0}^+ and the B\\,^3\\! \\Pi_{1}\\rightarrow X\\,^1\\!\\Sigma_{0}^+ transitions have been simulated. The program is based on the molecular constants and takes into account vibrational states up to v = 24. The required Franck-Condon factors and vibrationally resolved transition probabilities have been computed solving the Schrdinger equation using the Born-Oppenheimer approximation. The ground state density of the InBr molecule in the plasma has been determined from absorption spectra using effective transition probabilities for the A-X and B-X transition according to the vibrational population. The obtained densities agree well with densities derived from an Arrhenius type vapour pressure equation.

Briefi, S.; Fantz, U.

2011-04-01

253

Near-field investigation of spatial variations of (2021) InGaN quantum well emission spectra  

NASA Astrophysics Data System (ADS)

Scanning near-field optical spectroscopy was applied to semipolar (2021) InGaN/GaN quantum wells (QWs) to evaluate spatial homogeneity of QW band gap and its dependence on the growth conditions. In the most uniform QW, photoluminescence (PL) spectra were found to be narrow with small peak wavelength and spectral width variations. A QW grown at reduced temperature showed sub-micrometer size PL features aligned along the a axis and caused by nonuniform In incorporation at surface undulations. At extended defects, complex and strongly varying near-field spectra were observed and tentatively assigned to QW segments of different orientations around these defects.

Marcinkevi?ius, S.; Zhao, Y.; Kelchner, K. M.; Nakamura, S.; DenBaars, S. P.; Speck, J. S.

2013-09-01

254

Stratospheric ClONO[sub 2] and HNO[sub 3] profiles inside the Arctic vortex from MIPAS-B limb emission spectra obtained during EASOE  

SciTech Connect

The authors report vertical profile measurements of ClONO[sub 2] and HNO[sub 3] made using infrared limb emission spectra taken from a balloon borne instrument on 13 January and March 14/15, 1992. Very low ClONO[sub 2] densities were observed in January, while high numbers were seen in March. The authors interpret this as indicative of conversion of the molecule in January, while in March it indicates that most reactive chlorine is stored in this molecular form. The HNO[sub 3] measurements show no features which would indicate dramatic removal reactions such as on stratospheric clouds.

Oelhaf, H.; Clarmann, T.V.; Fischer, H.; Friedl-Vallon, F.; Fritzsche, Ch.; Linden, A.; Piesch, Ch.; Seefeldner, M.; Voelker, W. (Universitaet Karlsruhe (Germany))

1994-06-22

255

The Equilibrium and Pre-equilibrium Triton Emission Spectra of Some Target Nuclei for ( n, xt) Reactions up to 45 MeV Energy  

NASA Astrophysics Data System (ADS)

Although there have been significant research and development studies on the inertial and magnetic fusion reactor technology, there is still a long way to go to penetrate commercial fusion reactors to the energy market. Tritium self-sufficiency must be maintained for a commercial power plant. For self-sustaining (D-T) fusion driver tritium breeding ratio should be greater than 1.05. So, working out the systematics of ( n,t) reaction cross sections and triton emission differential data are important for the given reaction taking place on various nuclei at different energies. In this study, ( n,xt) reactions for some target nuclei as 16O, 27Al, 59Co and 209Bi have been investigated up to 45 MeV incident neutron energy. In the calculations of the triton emission spectra, the pre-equilibrium and equilibrium effects have been used. The calculated results have been compared with the experimental data taken from the literature.

Tel, E.; Kaplan, A.; Ayd?n, A.; zkorucuklu, S.; Bykuslu, H.; Y?ld?r?m, G.

2010-08-01

256

Theoretical modeling of UV-Vis absorption and emission spectra in liquid state systems including vibrational and conformational effects: The vertical transition approximation.  

PubMed

In this paper we describe in detail a general and efficient methodology, based on the perturbed matrix method and molecular dynamics simulations, to model UV-Vis absorption and emission spectra including vibrational and conformational effects. The basic approximation used is to consider all the chromophore atomic coordinates as semiclassical degrees of freedom, hence allowing the calculation of the complete spectral signal by using the electronic vertical transitions as obtained at each possible chromophore configuration, thus including the contributions of vibrations and conformational transitions into the spectrum. As shown for the model system utilized in this paper, solvated 1-phenyl-naphthalene, such an approximation can be rather accurate to reproduce the absorption and emission spectral line shape and properties when, as it often occurs, the vertical vibronic transition largely overlaps the other non-negligible vibronic transitions. PMID:24070274

D'Alessandro, Maira; Aschi, Massimiliano; Mazzuca, Claudia; Palleschi, Antonio; Amadei, Andrea

2013-09-21

257

Theoretical modeling of UV-Vis absorption and emission spectra in liquid state systems including vibrational and conformational effects: The vertical transition approximation  

NASA Astrophysics Data System (ADS)

In this paper we describe in detail a general and efficient methodology, based on the perturbed matrix method and molecular dynamics simulations, to model UV-Vis absorption and emission spectra including vibrational and conformational effects. The basic approximation used is to consider all the chromophore atomic coordinates as semiclassical degrees of freedom, hence allowing the calculation of the complete spectral signal by using the electronic vertical transitions as obtained at each possible chromophore configuration, thus including the contributions of vibrations and conformational transitions into the spectrum. As shown for the model system utilized in this paper, solvated 1-phenyl-naphthalene, such an approximation can be rather accurate to reproduce the absorption and emission spectral line shape and properties when, as it often occurs, the vertical vibronic transition largely overlaps the other non-negligible vibronic transitions.

D'Alessandro, Maira; Aschi, Massimiliano; Mazzuca, Claudia; Palleschi, Antonio; Amadei, Andrea

2013-09-01

258

Evolving mass spectra of the oxidized component of organic aerosol: results from aerosol mass spectrometer analyses of aged diesel emissions  

Microsoft Academic Search

The species and chemistry responsible for sec- ondary organic aerosol (SOA) formation remain highly un- certain. Laboratory studies of the oxidation of individual, high-flux SOA precursors do not lead to particles with mass spectra (MS) matching those of ambient aged organic ma- terial. Additionally, the complexity of real organic particles challenges efforts to identify their chemical origins. We have previously

A. M. Sage; E. A. Weitkamp; A. L. Robinson; N. M. Donahue

2008-01-01

259

A Proposal Of Accurate Scatter Correction Method Considering Energy Spectra Of Scattered Photons In Single Photon Emission CT  

Microsoft Academic Search

We have developed a new scatter correction method which considered energy spectra of scattered photons using four energy windows, i.e., three abutted energy windows (a left, a right, and a middle window) and a reference window. These three windows were located in the photopeak, and the reference window wm set in the lower energy region than the photopeak. In the

Akihiro Chugo; Koichi Ogawa

1993-01-01

260

Colour indices for the detection and differentiation of cloud types in infra-red limb emission spectra  

Microsoft Academic Search

Simple radiance ratios have been used for the detection of clouds around the tropopause and in the winter polar stratosphere from the infra-red spectra of two remote sensing instruments, the cryogenic infrared spectrometers and telescopes for the atmosphere (CRISTA) flown on two space shuttle missions in 1994 and 1997 and the Michelson interferometer for passive atmospheric sounding (MIPAS) launched on

R. Spang; J. J. Remedios; M. P. Barkley

2004-01-01

261

Emissions and ambient distributions of Biogenic Volatile Organic Compounds (BVOC) in a ponderosa pine ecosystem: interpretation of PTR-MS mass spectra  

NASA Astrophysics Data System (ADS)

Two proton-transfer-reaction mass spectrometry systems were deployed at the Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics and Nitrogen-Southern Rocky Mountain 2008 field campaign (BEACHON-SRM08; July to September, 2008) at the Manitou Forest Observatory in a ponderosa pine woodland near Woodland Park, Colorado USA. The two PTR-MS systems simultaneously measured BVOC emissions and ambient distributions of their oxidation products. Here, we present mass spectral analysis in a wide range of masses (m/z 40+ to 210+) to assess our understanding of BVOC emissions and their photochemical processing inside of the forest canopy. The biogenic terpenoids, 2-methyl-3-butene-2-ol (MBO, 50.2%) and several monoterpenes (MT, 33.5%) were identified as the dominant BVOC emissions from a transmission corrected mass spectrum (PTR-MS), averaged over the daytime (11 a.m. to 3 p.m., local time) of three days. To assess contributions of oxidation products of local BVOC, we calculate an oxidation product spectrum with the OH- and ozone-initiated oxidation product distribution mass spectra of two major BVOC emissions at the ecosystem (MBO and ?-pinene) that were observed from laboratory oxidation experiments. The majority (~76%) of the total signal in the transmission corrected PTR-MS spectra could be explained by identified compounds. The remainder are attributed to oxidation products of BVOC emitted from nearby ecosystems and transported to the site, and oxidation products of unidentified BVOC emitted from the ponderosa pine ecosystem.

Kim, S.; Karl, T.; Guenther, A.; Tyndall, G.; Orlando, J.; Harley, P.; Rasmussen, R.; Apel, E.

2010-02-01

262

Cassini UVIS Observations of Titan Ultraviolet Airglow Spectra with Laboratory Modeling from Electron- and Proton-Excited N2 Emission Studies  

NASA Astrophysics Data System (ADS)

Joseph M. Ajello, Robert A. West, Rao S. Mangina Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 Charles P. Malone Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 & Department of Physics, California State University, Fullerton, CA 92834 Michael H. Stevens Space Science Division, Naval Research Laboratory, Washington, DC 20375 Jacques Gustin Laboratoire de Physique Atmosphrique et Plantaire, Universit de Lige, Lige, Belgium A. Ian F. Stewart, Larry W. Esposito, William E. McClintock, Gregory M. Holsclaw Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80303 E. Todd Bradley Department of Physics, University of Central Florida, Orlando, FL 32816 The Cassini Ultraviolet Imaging Spectrograph (UVIS) observed photon emissions of Titan's day and night limb-airglow and disk-airglow on multiple occasions, including three eclipse observations from 2009 through 2010. The 77 airglow observations analyzed in this paper show EUV (600-1150 ) and FUV (1150-1900 ) atomic multiplet lines and band emissions (lifetimes less than ~100 ?s), including the Lyman-Birge-Hopfield (LBH) band system, arising from photoelectron induced fluorescence and solar photo-fragmentation of molecular nitrogen (N2). The altitude of peak UV emission on the limb of Titan during daylight occurred inside the thermosphere/ionosphere (near 1000 km altitude). However, at night on the limb, the same emission features, but much weaker in intensity, arise in the lower atmosphere below 1000 km (lower thermosphere, mesosphere, haze layer) extending downwards to near the surface at ~300 km, possibly resulting from proton- and/or heavier ion-induced emissions as well as secondary-electron-induced emissions. The eclipse observations are unique. UV emissions were observed during only one of the three eclipse events, and no Vegard-Kaplan (VK) or LBH emissions were seen. Through regression analysis using laboratory spectra, we have analyzed the intensity and identified each spectral feature from the limb or disk emission spectrum. The strongest dipole-allowed transitions of N2 occur in the EUV. The electronic transitions proceed from the X 1?g+ ground-state to about seven closely spaced (~12-15 eV) Rydberg-valence (RV) states, which are the source of the molecular emissions in the EUV observed by spacecraft and have recently been studied in our laboratory at medium-to-high spectral resolution (delta-? = 0.1 FWHM). Three of these RV states (b 1?u, b' 1?u+, and c4' 1?u+) are highly-perturbed, weakly-to-strongly predissociated, and have significant emission cross sections, which will be summarized in this paper. We will also discuss our recently published proton and electron impact emission cross sections for the LBH (a 1?g - X 1?g+) band system of N2, and their significance to the modeling of the day and night FUV spectra of the atmospheres of Earth and Titan.

Ajello, J. M.; West, R. A.; Malone, C. P.; Gustin, J.; Esposito, L. W.; McClintock, W. E.; Holsclaw, G. M.; Stevens, M. H.

2011-12-01

263

Lasers without inversion (LWI) in Space: A possible explanation for intense, narrow-band, emissions that dominate the visible and\\/or far-UV (FUV) spectra of certain astronomical objects  

Microsoft Academic Search

The optical or far-UV (FUV) spectra of certain objects in Space are completely dominated by one or two spectrally narrow emission lines, strongly suggesting that laser action of some kind occurs in these objects. However, the electronic level structures of the atoms\\/ions producing these emissions preclude the possibility of maintaining population inversions on the electronic transitions involved. In lasers, gain

P. P. Sorokin; J. H. Glownia

2002-01-01

264

The electronic spectrum of the fluoroborane free radical. II. Analysis of laser-induced fluorescence and single vibronic level emission spectra  

NASA Astrophysics Data System (ADS)

Subsequent to our spectroscopic detection of the HBX (X=F, Cl, Br) free radicals (S.-G. He, F. X. Sunahori, and D. J. Clouthier, J. Am. Chem. Soc. 127, 10814 (2005)), the electronic spectrum of the A~ 2A''?-X~ 2A' system of the fluoroborane (HBF) radical in the 600-745 nm region has been studied in detail using the pulsed discharge jet technique. The band system involves a linear-bent transition between the two Renner-Teller components of what would be a 2? state at linearity. Using the results of our theoretical study of the ground and excited state vibrational energy levels and 11B-10B isotope shifts (see the companion paper), the vibrational quantum numbers of the bands in the laser-induced fluorescence (LIF) spectra have been assigned. Rotational and vibrational analyses of the LIF and wavelength resolved emission spectra have been carried out, from which the linear excited state and the bent ground state equilibrium configurations have been confirmed. The ground state molecular geometry of HBF has been determined as r0(BH)=1.214(2) A?, r0(BF)=1.303 4(5) A?, and ?=120.7(1). Based on high-level ab initio calculations and symmetry considerations, predissociation of the excited state into H(2S)+BF(1?+) on the ground state potential energy surface is identified as the cause of the breaking off of fluorescence in the LIF spectra.

Sunahori, Fumie X.; Clouthier, Dennis J.

2009-04-01

265

Colour indices for the detection and differentiation of cloud types in infra-red limb emission spectra  

NASA Astrophysics Data System (ADS)

Simple radiance ratios have been used for the detection of clouds around the tropopause and in the winter polar stratosphere from the infra-red spectra of two remote sensing instruments, the cryogenic infrared spectrometers and telescopes for the atmosphere (CRISTA) flown on two space shuttle missions in 1994 and 1997 and the Michelson interferometer for passive atmospheric sounding (MIPAS) launched on ENVISAT in March 2002. This very successful approach was first applied to different wavelength regions of the CRISTA measurements and was then used as a pre-flight validation test for a cloud detection algorithm of the operational retrieval processor for MIPAS. Preliminary results are now available from the MIPAS instrument and are presented here. First, cloud top heights have been derived down to 12 km by the detection method and show quite reasonable results. In addition, modelled spectra and measurements show that the extension of the method to lower altitudes - potentially down to 6 km - should be possible. Second, the high spectral resolution of the MIPAS measurements allows in addition the detection of scattering effects in the spectra, which gives the future opportunity to retrieve information about the size of the scattering particles. In particular, an index has been developed which allows large particle clouds to be identified. Finally, investigations of CRISTA spectra have already shown that the differentiation of polar stratospheric cloud (PSC) types is possible based on their characteristic spectral features. Application of the differentiation method to the tropics shows no indication for clouds containing PSC-like nitric-acid-hydrate particles.

Spang, R.; Remedios, J. J.; Barkley, M. P.

2004-01-01

266

Optical and microphysical parameters of the Mt. Pinatubo aerosol as determined from MIPAS-B mid-IR limb emission spectra  

NASA Astrophysics Data System (ADS)

High-resolution mid-IR limb emission spectra were recorded during a flight of the Michelson interferometer for passive atmospheric sounding, balloon-borne version (MIPAS-B) from Kiruna, northern Sweden (68N) on March 14/15, 1992. These spectra are affected by the Mt. Pinatubo stratospheric aerosol, which caused an enhanced continuum emission, especially in spectra of low tangent altitudes. Aerosol extinction coefficients were retrieved from MIPAS-B spectra at approximately 60 spectral positions in the 750-980 cm-1 and 1180-1380 cm-1 spectral ranges. Retrieved aerosol extinction coefficients range from 610-4 km-1 to 310-3 km-1 in tangent altitudes 11.3 km and 14.5 km and from 510-5 km-1 to 110-3 km-1 in 16.1 km. Their distinct spectral shape indicates the presence of H2SO4-H2O droplets. Compositions and size distribution parameters were retrieved by least squares fitting of Mie-generated spectral extinction coefficients to the ones derived from the spectra. Estimated spectral single-scattering albedos between 0.08 and 0.3 indicate the significance of thermal multiple scattering. Multiple-scattering corrections led to an increase of spectral extinction coefficients by 5-50% with highest changes at lowest tangent altitudes. Accordingly, estimated volume densities have increased by 4-20% to values of 3.66, 2.85, and 0.93 ?m3 cm-3 for tangent altitudes 11.3, 14.5, and 16.1 km, respectively. Retrieved H2SO4 weights of 66-70% are in good agreement with values derived from stratospheric temperatures and water vapor partial pressures. Estimated surface densities are systematically low in comparison with in situ size distribution measurements. This finding is explained by the underestimation of small particles by the use of a monomodal size distribution in the analysis. Retrieved effective radii of up to 0.8 ?m were found to be consistent with the temporal evolution of the Mt. Pinatubo aerosol.

Echle, G.; von Clarmann, T.; Oelhaf, H.

1998-08-01

267

Retrieval of CO Mixing Ratios From the Atmospheric Emission Spectra of Down-Welling Middle IR Radiance in Oklahoma.  

NASA Astrophysics Data System (ADS)

CO abundances are retrieved from spectra of atmospheric down-welling radiation measured by the Atmospheric Emitted Radiance Interferometer (AERI) at the Southern Great Plains (SGP) observatory of the Atmospheric Radiation Measurements (ARM) program sponsored by the United States Department of Energy (DOE). These spectra measured every 8 minutes are publicly available for the period between 1997 and the present. The R-branch of the CO fundamental vibration-rotational band between 2135 and 2200 cm-1 is chosen for analysis. Radiative transfer calculations are performed using the k-Compressed Atmospheric Radiative Transfer Algorithm (kCARTA). Atmospheric temperature and water vapor profiles were retrieved from other parts of the AERI spectra using standard software developed by the University of Wisconsin and constrained with SGP Microwave Radiometer total precipitable water retrievals. An a priori constant CO mixing ratio profile is perturbed to minimize the spectral residuals due to CO. A correction for the scattered solar radiance during day-time is applied. Independent measurements of CO boundary layer mixing ratios by the Lawrence Berkeley National Laboratory (LBNL) and free tropospheric CO by the Earth System Research Laboratory (ESRL) of the Global Monitoring Division (GMD) , NOAA provide validation for the AERI retrieval technique.

Yurganov, L. N.; McMillan, W.; Wilson, C.; Fischer, M.; Biraud, S. C.; Novelli, P. C.

2009-05-01

268

Modification of ensemble emission rates and luminescence spectra for inhomogeneously broadened distributions of quantum dots coupled to optical microcavities.  

PubMed

We investigate the spontaneous emission modifications when ensembles of quantum dots (QDs) with differing emission frequencies and finite Lorentzian linewidths are coupled to a microcavity. Using contour integrals we develop a general expression for the rate enhancement when neither the emitter nor the cavity resonance can be treated as a delta function. We show that the ensemble cavity-coupled luminescence lifetimes are generally suppressed in the case of spherical cavities and that the spontaneous emission dynamics of the cavity coupled component becomes increasingly stretched as the coupling factor increases. The Q-factor measured from the luminescence spectrum can be much lower than the intrinsic cavity Q-factor, and is in many practical situations limited by the QD spectral width. The mode spectrum observed in the photoluminescence (PL) spectrum can be largely determined by the QD emission linewidth, permitting this parameter to be extracted without requiring single-particle spectroscopy. In the case of Si-QDs, the linewidth cannot be significantly greater than 10 meV in order to observe spherical cavity resonances in the PL spectrum. PMID:20588877

Meldrum, A; Bianucci, P; Marsiglio, F

2010-05-10

269

Effect of precursor mineralogy on the thermal infrared emission spectra of hematite: Application to Martian hematite mineralization  

Microsoft Academic Search

Observations from the Thermal Emission Spectrometer (TES) instrument aboard the Mars Global Surveyor (MGS) spacecraft led to the discovery of two isolated deposits of gray, crystalline hematite located in Meridiani Planum and Aram Chaos and several smaller deposits in Valles Marineris. Several pathways for formation of these hematite deposits have been proposed, involving both aqueous and nonaqueous processes. This work

T. D. Glotch; R. V. Morris; P. R. Christensen; T. G. Sharp

2004-01-01

270

Pressure and low temperature effects on the fluorescence emission spectra and lifetimes of the photosynthetic components of cyanobacteria.  

PubMed Central

The effects of hydrostatic pressure on the excited state reactions of the photosynthetic system of cyanobacteria were studied with the use of stationary and dynamic fluorescence spectroscopy. When the cells were excited with blue light (442 nm), hydrostatic pressure promoted a large increase in the fluorescence emission of the phycobilisomes (PBS). When PBS were excited at 565 nm, the shoulder originating from photosystem II (PSII) emission (F685) disappeared under 2.4 kbar compression, suggesting suppression of the energy transfer from PBS to PSII. At atmospheric pressure, the excited state decay was complex due to energy transfer processes, and the best fit to the data consisted of a broad Lorentzian distribution of short lifetimes. At 2.4 kbar, the decay data changed to a narrower distribution of longer lifetimes, confirming the pressure-induced suppression of the energy transfer between the PBS and PSII. When the cells were excited with blue light, the decay at atmospheric pressure was even more complex and the best fit to the data consisted of a two-component Lorentzian distribution of short lifetimes. Under compression, the broad distribution of lifetimes spanning the region 100-1,000 ps disappeared and gave rise to the appearance of a narrow distribution characteristic of the PBS centered at 1.2 ns. The emission of photosystem I underwent 2.2-fold increase at 2.4 kbar and room temperature. A decrease in temperature from 20 to -10 degrees C at 2.4 kbar promoted a further increase in the fluorescence emission from photosystem I to a level comparable with that obtained at temperatures below 120 degrees K and atmospheric pressure. On the other hand, when the temperature was decreased under pressure, the PBS emission diminished to very low value at blue or green excitation, suggesting the disassembly into the phycobiliprotein subunits.

Foguel, D; Chaloub, R M; Silva, J L; Crofts, A R; Weber, G

1992-01-01

271

Site-selective excitation and polarized absorption and emission spectra of trivalent thulium and erbium in strontium fluorapatite  

SciTech Connect

Polarized fluorescence spectra produced by site-selective excitation and conventional polarized absorption spectra were obtained for Tm{sup 3+} and Er{sup 3+} ions individually incorporated into single crystals of strontium fluorapatite, Sr{sub 5}(PO{sub 4}){sub 3}F. Substitution of the trivalent rare earth ion for divalent strontium was achieved by passive charge compensation during Czochralski growth of the fluorapatite crystals. Spectra were obtained between 1780 and 345 nm at temperatures from 4 K to room temperature on crystals having the hexagonal structure [P6{sub 3}/m(C{sub 6h}{sup 2})]. The polarized fluorescence spectra due to transitions from multiplet manifolds of Tm{sup 3+}(4f{sup 12}), including {sup 1}D{sub 2}, {sup 1}G{sub 4}, and {sup 3}H{sub 4} to manifolds {sup 3}H{sub 6} (the ground-state manifold), {sup 3}F{sub 4}, {sup 3}H{sub 5}, {sup 3}H{sub 4}, and {sup 3}F{sub 3} were analyzed for the details of the crystal-field splitting of the manifolds. Fluorescence lifetimes were measured for Tm{sup 3+} transitions from {sup 1}D{sub 2}, {sup 1}G{sub 4}, and {sup 3}H{sub 4} at room temperature and from {sup 1}G{sub 4} at 16 K. Results of the analysis indicate that the majority of Tm{sup 3+} ions occupy sites having C{sub s} symmetry. A point-charge lattice-sum calculation was made in which the crystal-field components, A{sub nm}, were determined assuming that trivalent thulium replaces divalent strontium in the metal site having C{sub s} symmetry. Results support the conclusion that the nearest-neighbor fluoride (F{sup {minus}}) is replaced by divalent oxygen (O{sup 2{minus}}), thus preserving overall charge neutrality and local symmetry. Crystal-field splitting calculations predict energy levels in agreement with experimental data. By varying the crystal-field parameters, B{sub nm}, we obtained a rms difference of 7cm{sup {minus}1} between 43 calculated and experimental Stark levels for Tm{sup 3+}(4f{sup 12}) in Tm:SFAP. (Abstract Truncated)

Gruber, J.B. [Department of Physics, San Jose State University, San Jose, California 95192-0106 (United States); Wright, A.O.; Seltzer, M.D. [Research and Technology Division, Naval Air Warfare Center, Code 474230D, China Lake, California 93555-6001 (United States); Zandi, B.; Merkle, L.D. [IR Optics Technology OFC, Army Research Laboratory, Ft. Belvoir, Virginia 22060-5838 (United States); Hutchinson, J.A. [Night Vision and Electronics Sensors Directorate, The United States Army, Ft. Belvoir, Virginia 22060-5806 (United States); Morrison, C.A. [Army Research Laboratory, Adelphi, Maryland 20783-1145 (United States); Allik, T.H. [Science Applications International Corporation, 1710 Goodridge Drive, McLean, Virginia 22102 (United States); Chai, B.H. [Center for Research on Electro-optics and Lasers, University of Central Florida, Orlando, Florida 32836 (United States)

1997-05-01

272

Infrared radiative transfer in atmospheres of Earth-like planets around F, G, K, and M stars. I. Clear-sky thermal emission spectra and weighting functions  

NASA Astrophysics Data System (ADS)

Context. The atmosphere of Earth-like extrasolar planets orbiting different types of stars is influenced by the spectral dependence of the incoming stellar radiation. The changes in structure and composition affect atmospheric radiation, hence the spectral appearance of these exoplanets. Aims: We provide a thorough investigation of infrared radiative transfer in cloud-free exoplanets atmospheres by not only analyzing the planetary spectral appearance but also discussing the radiative processes behind the spectral features in detail and identifying the regions in the atmosphere that contribute most at a given wavelength. Methods: Using cloud-free scenarios provided by a one-dimensional radiative-convective steady-state atmospheric model, we computed high-resolution infrared transmission and emission spectra, as well as weighting functions for exoplanets located within the habitable zone of F, G, K, and M stars by means of a line-by-line molecular absorption model and a Schwarzschild solver for the radiative transfer. The monochromatic spectra were convolved with appropriate spectral response functions to study the effects of finite instrument resolution. Results: Spectra of the exoplanets of F, G, K, and M stars were analyzed in the 4.5 ?m N2O band, the 4.3 ?m and 15 ?m CO2 bands, the 7.7 ?m CH4 band, the 6.3 ?m H2O band, and the 9.6 ?m O3 band. Differences in the state of the atmosphere of the exoplanets clearly show up in the thermal infrared spectra; absorption signatures known from Earth can be transformed to emission features (and vice versa). Weighting functions show that radiation in the absorption bands of the uniformly mixed gases (CO2, CH4, N2O) and (to some extent) ozone comes from the stratosphere and upper troposphere, and also indicate that changes in the atmospheres can shift sources of thermal radiation to lower or higher altitudes. Molecular absorption and/or emission features can be identified in the high-resolution spectra of all planets and in most reduced resolution spectra. Conclusions: Insight into radiative transfer processes is essential for analyzing exoplanet spectral observations; for instance, understanding the impact of the temperature profile (nb. non-existence of an inversion) on the CO2 bands facilitates their interpretation and can help avoid false positive or negative estimates of O3. The detailed analysis of the radiation source and sink regions could even help give an indication about the feasibility of identifying molecular signatures in cloud-covered planets, i.e. radiation mainly coming from the upper atmosphere is less likely to be hidden by clouds. Infrared radiative transfer and biomarker detectability in cloud-covered exoplanets will be presented in a companion paper. Appendix is available in electronic form at http://www.aanda.org

Vasquez, M.; Schreier, F.; Gimeno Garca, S.; Kitzmann, D.; Patzer, B.; Rauer, H.; Trautmann, T.

2013-01-01

273

Emissions and ambient distributions of Biogenic Volatile Organic Compounds (BVOC) in a Ponderosa pine ecosystem: interpretation of PTR-MS mass spectra  

NASA Astrophysics Data System (ADS)

Two proton-transfer-reaction mass spectrometry systems were deployed at the Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics and Nitrogen-Southern Rocky Mountain 2008 field campaign (BEACHON-SRM08; July to September 2008) at the Manitou Forest observatory in a Ponderosa pine woodland near Woodland Park, Colorado USA to simultaneously measure BVOC emissions and ambient distributions of their oxidation products. Here, we present mass spectral analysis in a wide range of masses (m/z=40+ to 210+) to assess our understanding of BVOC emissions and their photochemical process inside of the forest canopy. The biogenic terpenoids, 2-methyl-3-butene-2-ol (MBO, 50.2%) and several monoterpenes (MT, 33.5%) were identified as the dominant BVOC emissions from a transmission corrected mass spectrum, averaged over the daytime (11 am to 3 p.m., local time) of three days. To assess contributions of oxidation products of local BVOC, we calculate a oxidation product spectrum with the OH- and ozone-initiated oxidation product distribution mass spectra of two major BVOC at the ecosystem (MBO and ?-pinene) that were observed from laboratory oxidation experiments. A majority (~73%) of the total signal could be explained by known compounds. The remainder are attributed to oxidation products of BVOC, emitted from nearby ecosystems and transported to the site, and oxidation products of unidentified BVOC emitted from the Ponderosa pine ecosystem.

Kim, S.; Karl, T.; Guenther, A.; Tyndall, G.; Orlando, J.; Harley, P.; Rasmussen, R.; Apel, E.

2009-10-01

274

Effects of Palagonitic and Basaltic Dust Coatings on Visible, Near-IR, Thermal Emission and Moessbauer Spectra of Rocks and Minerals: Implications for Mineralogical Remote Sensing of Mars  

NASA Astrophysics Data System (ADS)

Dust coatings on the surface of Mars complicate and, if sufficiently thick, mask the detection of the mineralogical signatures of the underling material from remote sensing instrumentation aboard orbiters, landers and rovers. An air-fall method for depositing fine-grained material (<50 microns) was developed to uniformly coat rock (basalt, andesite, kaolinite and quartz claystone, schistose hematite) and mineral (olivine, pyroxmangite, siderite) substrates to thicknesses up to ~2000 microns. Dust analogs used to date include, palagonite from the summit region of Mauna Kea Volcano (Hawaii) and crushed basaltic material from Mulcahy Lake (Canada). The method allows for the determination of spectral effects resulting from various thicknesses of dust accumulation with numerous experiment techniques (visible, near-IR, thermal emission and backscatter Moessbauer spectroscopy). Results demonstrate that infinite optical thickness in the visible wavelengths (350-700 nanometers) is on the order of 10-35 and 10-55 microns for palagonitic and basaltic dust coatings, respectively. Band features for all the substrates were complete diminished in the near-IR (700-2100 nanometers) with coatings of ~300 microns for both dust analogs. In the thermal emission spectra (2000-200 wavenumbers) the emissivity spectrum of the substrate was obscured with dust thicknesses of 150-250 microns. Palagonitic dust coatings ~2000 microns thick (~25 mg/cm2) were not sufficient to mask the substrate material from the 14.4 kev gamma-rays used in the Moessbauer experiments.

Graff, T. G.; Morris, R. V.; Christensen, P. R.

2002-12-01

275

Absorption and emission UV-Vis spectra of the TRITC fluorophore molecule in solution: a quantum mechanical study.  

PubMed

The absorption and emission properties as well as the electronic structure in the ground (S(0)) and excited (S(1)) states of tetramethylrhodamine isothiocyanate (TRITC) fluorophore molecule have been investigated by time-dependent density functional theory (TD-DFT). The effect of water and ethanol solvents on the structure and optical properties of the dye was taken into account by using both explicit and implicit solvent models, as well as combinations of them.Different hybrid and long range corrected functionals have been tested in reproducing absorption and emission transition energies. It has been found that the B3LYP functional coupled with mixed explicit/implicit solvent models reproduces correctly experimental data concerning both the solvent and Stokes shifts. This work presents a first step to a more challenging project devoted to the development of integrated multiscale approaches and protocols for studying optical properties of fluoroprobes embedded in biological systems and/or encapsulated in nanoparticles of technological interest. PMID:20066385

Pedone, Alfonso; Bloino, Julien; Monti, Susanna; Prampolini, Giacomo; Barone, Vincenzo

2009-12-03

276

An iterative method in a probabilistic approach to the spectral inverse problem. Differential emission measure from line spectra and broadband data  

NASA Astrophysics Data System (ADS)

Context. Inverse problems are of great importance in astrophysics, e.g., for deriving information about the physical characteristics of hot optically thin plasma sources from their extreme ultraviolet and X-ray spectra. Aims: We describe and test an iterative method developed within the framework of a probabilistic approach to the spectral inverse problem for determining the thermal structures of the emitting plasma. We also demonstrate applications of this method to both high resolution line spectra and broadband imaging data. Methods: Our so-called Bayesian iterative method (BIM) is an iterative procedure based on Bayes' theorem and is used to reconstruct differential emission measure (DEM) distributions. Results: To demonstrate the abilities of the BIM, we performed various numerical tests and model simulations establishing its robustness and usefulness. We then applied the BIM to observable data for several active regions (AR) previously analyzed with other DEM diagnostic techniques: both SUMER/SOHO (Landi & Feldman 2008, ApJ, 672, 674) and SPIRIT/CORONAS-F (Shestov et al. 2010, Astron. Lett., 36, 44) line spectra data, and XRT/Hinode (Reale et al. 2009, ApJ, 698, 756) broadband imaging data. The BIM calculations confirmed the main results for SUMER/SOHO data showing very good quantitative agreement between both DEMs at log T ? 6.5 (T is the temperature in units of Kelvin) and a slight shift for two maxima at lower temperatures with ?30-50% difference in the DEM values for the coolest peak. For the SPIRIT data, we revised and validated AR DEM results including the inference of hot plasma in ARs with an emission measure (EM) at temperatures ?9-15 MK comparable to the EM at ?2-4 MK. In the case of XRT broadband data, the BIM solutions provided evidence of hot plasma at temperatures ?4-6 MK with EM up to ~30% as compared to that at ?2-4 MK in a non-flaring AR on 2006 November 12. Conclusions: The BIM results show that this method is an effective tool for determining the thermal structure of emitting plasma and can be successfully used for the DEM analysis of both line spectra and broadband imaging data. The BIM calculations correlate with recent studies confirming the existence of hot plasma in solar ARs. The BIM results also indicate that the coronal plasma may have the continuous distributions predicted by the nanoflare paradigm.

Goryaev, F. F.; Parenti, S.; Urnov, A. M.; Oparin, S. N.; Hochedez, J.-F.; Reale, F.

2010-11-01

277

Diagnosis of core-shell mixing with absorption and emission spectra of a doped layer. Final technical report  

SciTech Connect

We carried out the proposed program as planned. The research work has resulted in several publications, see attachments. The objective of this proposal was to develop a diagnostic method for core-shell mixing, based on the observation of absorption and emission lines of a doped layer, embedded within the shell, and correlate these signatures with nuclear signatures of target performance. We showed the results of a numerical analysis applied to a particular doped target imploded on the OMEGA system as a feasibility demonstration.

NONE

1998-05-01

278

Calculation of the recoilless ?-ray emission spectra from a substitutional cation impurity diffusing via the <001> channels in the rutile structure  

NASA Astrophysics Data System (ADS)

The large anisotropy of the diffusion coefficient for a substitutional randomly diluted cationic impurity in the rutile structure, with the diffusivity being much larger along the tetragonal axis as compared to the diffusivity within a tetragonal plane, indicates that open and almost empty <001> channels are involved along with an interstitialcy mechanism to originate diffusion events leading an impurity from one to another substitutional cationic site. This model is used to evaluate the resulting emission Mssbauer spectra of the impurity staying locally at equilibrium with the lattice and embedded in a single-crystalline sample. Final results are shown for the 14.4 keV Mssbauer line in 57Co (Fe). It is shown that channel diffusivity is governed by the exponential law, and details of the electric-field-gradient relaxation due to the diffusive motion of the probe are described from first principles.

Ruebenbauer, K.; Wdowik, U. D.; Kwater, M.

1996-08-01

279

Analysis of transmission spectra for large ratio of emission-to-absorber linewidths: extension of differential absorption lidar analysis for finite laser linewidths.  

PubMed

A simple algorithm is presented for the analysis of transmission spectra provided by a lidar with an emission linewidth that is comparable with or larger than the absorption features of interest. The spreading of line shapes as seen by the lidar precludes use of the classical differential absorption lidar (DIAL) approach. However, it is assumed that, as with the DIAL method, small spectral intervals exist where single absorbers are dominant, and an inversion process for the transmission over such intervals is carried out for the absorber concentration. A second-stage algorithm based on singular-value decomposition is also provided to improve further the concentration estimates. An example situation for use of the algorithms is included wherein the objective is to estimate the concentration of a known trace gas in a composite transmission spectrum in the mid-infrared, where the dominant absorbers are water vapor and methane. PMID:16045223

Klett, James D

2005-07-10

280

Electron emission spectra of thermal collisions of He metastable atoms with Au(111) and Pt(111) surfaces: Evidence for Penning ionization  

SciTech Connect

Electron emission spectra obtained by thermal collisions of He*(2{sup 1}S and 2{sup 3}S) atoms with Au(111) and Pt(111) surfaces were measured to clarify the electronically excited atom-metal interactions. It has been recognized that the metastable atoms de-excite on ordinary noble- and transition-metal surfaces via resonance ionization (RI) followed by Auger neutralization (AN) without no indication of Penning ionization (PI). Our data show that this traditional criterion partially breaks down in the He*-Au(111) collision system. The local electronic states near the surface were examined by first-principles calculations using density functional theory. It reveals that the itinerant sp states are significantly spilled out toward the vacuum compared to the localized 5d states, and their asymptotic features play a crucial role in determining the branching ratio between PI and RI+AN.

Masuda, S.; Sasaki, K.; Sogo, M.; Aoki, M. [Department of Basic Science, Graduate School of Arts and Sciences, University of Tokyo, Komaba, Meguro, Tokyo 153-8902 (Japan); Morikawa, Y. [Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan)

2009-10-15

281

Emission spectra and invariant masses of ? and p in the stopped-KNN absorption process in 4He and 6Li  

NASA Astrophysics Data System (ADS)

We have calculated the emission spectra of Y and N and invariant masses of YN pairs in the direct KNN?YN absorption process at rest in 4He and light nuclei in order to provide theoretical tools for correct interpretations of experimental data with or without invoking kaonic nuclear bound states. All the momentum distributions are broad with widths around 150 200 MeV/c (except for the case of 6Li target), while the partial invariant mass of each YN pair has a peak around 2310 2330 MeV/c2. We argue against the interpretations of stopped-K experimental data of KEK and FINUDA by Oset and Toki and by Magas, Oset, Ramos and Toki.

Yamazaki, Toshimitsu; Akaishi, Yoshinori

2007-08-01

282

Chemical analysis of industrial scale deposits by combined use of correlation coefficients with emission line detection of laser induced breakdown spectroscopy spectra  

NASA Astrophysics Data System (ADS)

Laser-induced breakdown spectroscopy (LIBS) was used to determine the mineral composition of various industrial scale samples. The aim of the study has been to investigate the capacity of LIBS to provide a fast, reliable analytical tool for carrying out routine analysis of inorganic scales, potentially on site, as a means to facilitate decision making concerning scale removal procedures. LIBS spectra collected in the range of 200-660 nm conveyed information about the metal content of the minerals. Via a straightforward analysis based on linear correlation of LIBS spectra it was possible to successfully discriminate scale samples into three main groups, Fe-rich, Ca-rich and Ba-rich, on the basis of correlation coefficients. By combining correlation coefficients with spectral data collected in the NIR, 860-960 nm, where sulfur emissions are detected, it became further possible to discriminate sulfates from carbonates as confirmed by independent analysis based on Raman spectroscopy. It is emphasized that the proposed LIBS-based method successfully identifies the major mineral or minerals present in the samples classifying the scales into relevant groups hence enabling process engineers to select appropriate scale dissolution strategies.

Siozos, P.; Philippidis, A.; Hadjistefanou, M.; Gounarakis, C.; Anglos, D.

2013-09-01

283

LETTER TO THE EDITOR: Energy levels of 4f3 in the Nd3+ free ion from emission spectra  

NASA Astrophysics Data System (ADS)

The emission spectrum of neodymium produced by vacuum spark sources was observed in the vacuum ultraviolet on two normal-incidence spectrographs. In an initial result, more than 550 lines have been identified as transitions from 85 4f25d levels to 37 levels of the 4f3 ground configuration in the free ion Nd3+. The levels 4f34F3/2 and 4I11/2, responsible for the well-known 1064 nm laser line, have respective positions of 11 698.57 0.1 cm-1 and 1897.07 0.1 cm-1 above the ground level 4I9/2. The newly found levels of 4f3 constitute the first isolated 4fN configuration (N > 2) and therefore enable checks of effective parameters that represent far configuration interaction. Slater parameters Fk(4f, 4f) derived from Nd3+:LaCl3 are 3% to 5% smaller than in the free ion.

Wyart, Jean-Franois; Meftah, Ali; Bachelier, Annik; Sinzelle, Jocelyne; Tchang-Brillet, Wan-. Lydia; Champion, Norbert; Spector, Nissan; Sugar, Jack

2006-03-01

284

Rotational analysis and deperturbation of the A 2? --> X 2?+ and B' 2?+ --> X 2?+ emission spectra of MgH  

NASA Astrophysics Data System (ADS)

Deperturbation analysis of the A 2? --> X 2?+ and B' 2?+ --> X 2?+ emission spectra of 24MgH is reported. Spectroscopic data for the v = 0 to 3 levels of the A 2? state and the v = 0 to 4 levels of the B' 2?+ state were fitted together using a single Hamiltonian matrix that includes 2? and 2?+ matrix elements, as well as off-diagonal elements coupling several vibrational levels of the two states. A Dunham-type fit was performed and the resulting Yl,0 and Yl,1 coefficients were used to generate Rydberg-Klein-Rees (RKR) potential curves for the A 2? and the B' 2?+ states. Vibrational overlap integrals were computed from the RKR potentials, and the off-diagonal matrix elements coupling the electronic wavefunctions (a+ and b) were determined. Zero point dissociation energies (D0) of the A 2? and B' 2?+ states of 24MgH were determined to be 12 957.5 +/- 0.5 and 10 133.6 +/- 0.5 cm-1, respectively. Using the Y0,1 coefficients, the equilibrium internuclear distances (re) of the A 2? and B' 2?+ states were determined to be 1.67827(1) A? and 2.59404(4) A?, respectively.

Shayesteh, Alireza; Bernath, Peter F.

2011-09-01

285

Alpha Emission Spectra of 27Al, 50,52Cr, 55Mn, 54,56Fe, 58,60Ni Nucleus for Neutron Induced Reaction  

NASA Astrophysics Data System (ADS)

The design of novel nuclear facilities, fusion as well as fission reactors, requires the knowledge of all properties of relevant materials, including the nuclear differential cross sections for a careful selection. The nuclear cross sections data for gas production via particle (neutron, proton, alpha, etc.) induced reactions are great importance in the domain in the fusion reactor technology, particularly in the calculation of nuclear transmutation rates, nuclear heating and radiation damage due to gas formation. In fusion reactor structures, a serious damage mechanism has been gas production in the metallic resulting from diverse nuclear reactions, mainly through (n, p) and (n, ?), (n, d), (n, t). In the present study, by using equilibrium reaction mechanisms, the (n, x?) reaction alpha emission spectra for 27Al, 50,52Cr, 55Mn, 54,56Fe, 58,60Ni isotopes were investigated from 9 to 15 MeV incident neutron energy. The equilibrium results have been calculated by using the hybrid model, the geometry dependent hybrid model. Calculation results have been also compared with the available measurements in literature.

Tel, E.; Gokce, A. A.; Ugur, F. A.; Kara, A.

2013-06-01

286

The effect of high temperatures on the mid-to-far-infrared emission and near-infrared reflectance spectra of phyllosilicates and natural zeolites: Implications for martian exploration  

NASA Astrophysics Data System (ADS)

Most phyllosilicates on Mars appear to be associated with ancient terrains. As such, they may have experienced shock heating produced by impacts and could have been significantly altered or melted. We characterized the effects of high temperatures on the mid-to-far-infrared (mid-to-far-IR) emission (100-1400 cm-1; 7.1-100 ?m) and near-infrared (NIR) reflectance (1.2-2.5 ?m) spectra of phyllosilicates by measuring experimentally calcined (100-900 C) phyllosilicates and also two zeolites. Correlated differential scanning calorimetry (DSC) measurements were also performed on each sample to provide insight into the thermal activities of the phyllosilicates and natural zeolites. Our results indicate that all phyllosilicates exhibit characteristic degradations in both NIR and mid-to-far-IR spectral properties between 400 and 800 C, mainly attributable to the dehydroxylation and recrystallization processes as temperature increases. Spectral features of natural zeolites persist to higher temperatures compared to features of phyllosilicates during heating treatments. The thermal behaviors of phyllosilicate infrared (IR) properties are greatly influenced by the compositions of the octahedral cations: (1) changes in both the NIR and mid-to-far-IR spectra of phyllosilicates tend to occur at lower temperatures (300-400 C) in the Fe3+-rich samples as compared to the Al3+-rich types (400-600 C); (2) Mg2+-trioctahedral phyllosilicates hectorite, saponite, and sepiolite all display major mid-to-far-IR spectral changes at 700 C, corresponding to the formation of enstatite; (3) phyllosilicates that have minor replacement of Mg2+ for Al3+ in octahedral positions (e.g. cheto-type montmorillonite and palygorskite) show an absorption band at 920 cm-1 that becomes strong at 900 C. Inconsistency between spectral behaviors in the mid-to-far-IR and NIR regions is also discussed for phyllosilicates. Results from this study have provided suggestive evidence for the scenario that some phyllosilicates could lose all original spectral features in mid-to-far-IR region while maintaining their characteristic hydration bands in NIR region in the same temperature range.

Che, Congcong; Glotch, Timothy D.

2012-03-01

287

Global peroxyacetyl nitrate (PAN) retrieval in the upper troposphere from limb emission spectra of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS)  

NASA Astrophysics Data System (ADS)

We use limb emission spectra of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) onboard the ENVIronmental SATellite (ENVISAT) to derive the first global distribution of peroxyacetyl nitrate (PAN) in the upper troposphere. PAN is generated in tropospheric air masses polluted by fuel combustion or biomass burning and acts as a reservoir and carrier of NOx in the cold free troposphere. Since PAN exhibits continuum-like broadband structures in the mid-infrared region, we have applied a contiguous analysis window covering the wavenumber region 775-800 cm-1 for retrieval. The interfering species CCl4, HCFC-22, H2O, ClONO2, CH3CCl3 and C2H2 were fitted along with PAN, whereas pre-fitted profiles were used to model the contribution of other contaminants like ozone. Sensitivity tests consisting in retrieval without consideration of PAN have demonstrated the existence of PAN signatures in MIPAS spectra obtained from polluted air masses. The analysed dataset consists of 10 days between 4 October and 1 December 2003. This period covers the end of the biomass burning season in South America and South and East Africa, in which generally large amounts of pollutants are produced and distributed over wide areas in the southern hemispheric free troposphere. Elevated PAN amounts of 200-700 pptv were measured in a large plume extending from Brasil over the Southern Atlantic, Central and South Africa, the South Indian Ocean as far as Australia at altitudes between 8 and 16 km. Enhanced PAN values were also found in a much more restricted area between northern subtropical Africa and India. The most significant northern midlatitude PAN signal in MIPAS data is an area extending at 8 km altitude from China into the Chinese Sea. The average mid and high latitude PAN amounts found at 8 km were around 125 pptv in the northern, but only between 75 and 50 pptv in the southern hemisphere. The PAN distribution found in the southern hemispheric tropics and subtropics is highly correlated with the jointly fitted acetylene (C2H2), which is another pollutant produced by biomass burning, and agrees reasonably well with the CO plume detected during end of September 2003 at the 275 hPa level (~10 km) by the Measurement of Pollution in the Troposphere (MOPITT) instrument on the Terra satellite. Similar southern hemispheric PAN amounts were also observed by previous airborne measurements performed in September/October 1992 and 1996 above the South Atlantic and the South Pacific, respectively.

Glatthor, N.; von Clarmann, T.; Fischer, H.; Funke, B.; Grabowski, U.; Hpfner, M.; Kellmann, S.; Kiefer, M.; Linden, A.; Milz, M.; Steck, T.; Stiller, G. P.

2007-01-01

288

Global peroxyacetyl nitrate (PAN) retrieval in the upper troposphere from limb emission spectra of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS)  

NASA Astrophysics Data System (ADS)

We use limb emission spectra of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) onboard the ENVIronmental SATellite (ENVISAT) to derive the first global distribution of peroxyacetyl nitrate (PAN) in the upper troposphere. PAN is generated in tropospheric air masses polluted by fuel combustion or biomass burning and acts as a reservoir and carrier of NOx in the cold free troposphere. PAN exhibits continuum-like broadband structures in the mid-infrared region and was retrieved in a contiguous analysis window covering the wavenumber region 775-800 cm-1. The interfering species CCl4, HCFC-22, H2O, ClONO2, CH3CCl3 and C2H2 were fitted along with PAN, whereas pre-fitted profiles were used to model the contribution of other contaminants like ozone. Sensitivity tests consisting in retrieval without consideration of PAN demonstrated the existence of PAN signatures in MIPAS spectra obtained in polluted air masses. The analysed dataset consists of 10 days between 4 October and 1 December 2003. This period covers the end of the biomass burning season in South America and South and East Africa, in which generally large amounts of pollutants are produced and distributed over wide areas of the southern hemispheric free troposphere. Indeed, elevated PAN amounts of 200-700 pptv were measured in a large plume extending from Brasil over the Southern Atlantic, Central and South Africa, the South Indian Ocean as far as Australia at altitudes between 8 and 16 km. Enhanced PAN values were also found in a much more restricted area between northern subtropical Africa and India. The most significant northern midlatitude PAN signal was detected in an area at 8 km altitude extending from China into the Chinese Sea. The average mid and high latitude PAN amounts found at 8 km were around 125 pptv in the northern, but only between 50 and 75 pptv in the southern hemisphere. The PAN distribution found in the southern hemispheric tropics and subtropics is highly correlated with the jointly fitted acetylene (C2H2), which is another pollutant produced by biomass burning, and agrees reasonably well with the CO plume detected during end of September 2003 at the 275 hPa level (~10 km) by the Measurement of Pollution in the Troposphere (MOPITT) instrument on the Terra satellite. Similar southern hemispheric PAN amounts were also observed by previous airborne measurements performed in September/October 1992 and 1996 above the South Atlantic and the South Pacific, respectively.

Glatthor, N.; von Clarmann, T.; Fischer, H.; Funke, B.; Grabowski, U.; Hpfner, M.; Kellmann, S.; Kiefer, M.; Linden, A.; Milz, M.; Steck, T.; Stiller, G. P.

2007-06-01

289

F-GAMMA program: Unification and physical interpretation of the radio spectra variability patterns in Fermi blazars and detection of radio jet emission from NLSY1 galaxies  

NASA Astrophysics Data System (ADS)

The F-GAMMA program aims at understanding the physics at work in AGN via a multi-frequency monitoring approach. A number of roughly 65 Fermi-GST detectable blazars are being monitored monthly since January 2007 at radio wavelengths. The core program relies on the 100-m Effelsberg telescope operating at 8 frequencies between 2.6 and 43 GHz, the 30-m IRAM telescope observing at 86, 145 and 240 GHz and the APEX 12-m telescope at 345 GHz. For the targeted sources the LAT instrument onboard Fermi-GST provides gamma-ray light curves sampled daily. Here we discuss two recent findings: A). On the basis of their variability pattern, the observed quasi-simultaneous broad-band spectra can be classified to merely 5 classes. The variability for the first 4 is clearly dominated by spectral-evolution. Sources of the last class vary self-similarly with almost no apparent shift of the peak frequency. The former classes can be attributed to a two-component principal system made of a quiescent optically thin spectrum and a super-imposed flaring event. The later class must be interpreted in terms of a completely different mechanism. The apparent differences among the classes are explained in terms of a redshift modulus and an intrinsic-source/flare parameters modulus. Numerical simulations have shown that a shock-in-jet model can very well describe the observed behavior. It is concluded therefore that only two mechanisms seem to be producing variability. None of the almost 90 sources used for this study show a switch of class indicating that the variability mechanism is either (a) a finger-print of the source, or (b) remains stable on timescales far longer than the monitoring period of almost 4 years. B). Recently it has been disclosed that Narrow Line Seyfert 1 galaxies show gamma-ray emission. Within the F-GAMMA program radio jet emission has been detected from 3 such sources challenging the belief that jets are associated with elliptical galaxies. The recent findings in this area will be discussed.

Angelakis, E.

2012-01-01

290

[Formation and emission spectra of C2 Swan bands during the reaction of laser ablation Al plume with CF4, CCl4 and CH2Br2 beams].  

PubMed

The emission spectra of C2 Swan bands transition were observed in 430-600 nm region by Q-switched laser ablation target of Al reacting with CF4, CCl4 and CH2Br2 beams. Five vibration band sequences (delta v = 2, 1, 0, -1 and -2) of d3 pi(g)-a3 pi(g) were identified and the largest vibration number of excited state d is 6. Using a local thermal equilibrium model, the vibrational temperature of d state was determined to be about 6000 K. Meanwhile, some bumps, separated by about 0.3 nm, were observed between vibrational bands of delta v = 0 and -1 sequences, which were due to accidental and periodical accumulations of rotational lines belonging to several vibrational bands. The formation mechanism of excited C2 d3 pi(g) state is considered as when laser induced Al plasma expansion in the background reaction gas sample, the collisions between metal particles and gas sample molecules cause the dissociation of precursors, so atomic C is produced. Meanwhile, the shock wave induced by plasma expansion might cause molecules dissociation as well. Then C atoms combine to form C2 in the ground state X1 sigma(g)+ (Te = 0 cm(-1)) or first excited state a3 pi(u) = (Te = 716 cm(-1)). The electronic energy transfer between excited state Al (2S(1/2)) (Te = 25,348 cm(-1)) and C2 a3 pi(u) state produces the excited state d3 pi(g) (Te = 20,022 cm(-1)). Another mechanism that may be possible is that b3 sigma(g)+ state of C2 is produced first, then undergoes a radiationless transition into d3 pi(g) state through crossing with the d3 pi(g), v' = 6 level. But the vibrational population of v' < 6 levels isformed by collision relaxation. PMID:15762455

Zhang, Shu-dong; Li, Hai-yang

2004-11-01

291

SUZAKU OBSERVATION OF STRONG FLUORESCENT IRON LINE EMISSION FROM THE YOUNG STELLAR OBJECT V1647 ORI DURING ITS NEW X-RAY OUTBURST  

SciTech Connect

The Suzaku X-ray satellite observed the young stellar object (YSO) V1647 Ori on 2008 October 8 during the new mass accretion outburst reported in 2008 August. During the 87 ks observation with a net exposure of 40 ks, V1647 Ori showed a high level of X-ray emission with a gradual decrease in flux by a factor of 5 and then displayed an abrupt flux increase by an order of magnitude. Such enhanced X-ray variability was also seen in XMM-Newton observations in 2004 and 2005 during the 2003-2005 outburst, but has rarely been observed for other YSOs. The spectrum clearly displays emission from Helium-like iron, which is a signature of hot plasma (kT {approx} 5 keV). It also shows a fluorescent iron K{alpha} line with a remarkably large equivalent width (EW) of {approx}600 eV. Such a large EW suggests that a part of the incident X-ray emission that irradiates the circumstellar material and/or the stellar surface is hidden from our line of sight. XMM-Newton spectra during the 2003-2005 outburst did not show a strong fluorescent iron K{alpha} line, so that the structure of the circumstellar gas very close to the stellar core that absorbs and re-emits X-ray emission from the central object may have changed in between 2005 and 2008. This phenomenon may be related to changes in the infrared morphology of McNeil's nebula between 2004 and 2008.

Hamaguchi, Kenji [CRESST and X-ray Astrophysics Laboratory NASA/GSFC, Greenbelt, MD 20771 (United States); Grosso, Nicolas [Universite de Strasbourg, Observatoire Astronomique de Strasbourg, 11 rue de l'universite, 67000 Strasbourg (France); Kastner, Joel H.; Richmond, Michael [Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623 (United States); Weintraub, David A. [Vanderbilt University, Nashville, TN 37235 (United States)], E-mail: Kenji.Hamaguchi@nasa.gov

2010-05-01

292

A newly discovered DLA and associated Ly? emission in the spectra of the gravitationally lensed quasar UM673A,B  

NASA Astrophysics Data System (ADS)

The sightline to the brighter member of the gravitationally lensed quasar pair UM673A,B intersects a damped Ly? system (DLA) at z = 1.62650 which, because of its low redshift, has not been recognized before. Our high-quality echelle spectra of the pair, obtained with HIRES on the Keck I telescope, show a drop in neutral hydrogen column density N(HI) by a factor of at least 400 between UM673A and UM673B, indicating that the DLA's extent in this direction is much less than the 2.7 h-170kpc separation between the two sightlines at z = 1.62650. By re-assessing this new case together with published data on other quasar pairs, we conclude that the typical size (radius) of DLAs at these redshifts is R ~= (5 +/- 3) h-170kpc, smaller than previously realized. Highly ionized gas associated with the DLA is more extended, as we find only small differences in the CIV absorption profiles between the two sightlines. Coincident with UM673B, we detect a weak and narrow Ly? emission line which we attribute to star formation activity at a rate SFR >~ 0.2Msolaryr-1. The DLA in UM673A is metal poor, with an overall metallicity ZDLA ~= 1/30Zsolar, and has a very low internal velocity dispersion. It exhibits some apparent peculiarities in its detailed chemical composition, with the elements Ti, Ni and Zn being deficient relative to Fe by factors of 2-3. The [Zn/Fe] ratio is lower than those measured in any other DLA or Galactic halo star, presumably reflecting somewhat unusual previous enrichment by stellar nucleosynthesis. We discuss the implications of these results for the nature of the galaxy hosting the DLA. Based on data obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and NASA, and was made possible by the generous financial support of the W. M. Keck Foundation. E-mail: rcooke@ast.cam.ac.uk

Cooke, Ryan; Pettini, Max; Steidel, Charles C.; King, Lindsay J.; Rudie, Gwen C.; Rakic, Olivera

2010-12-01

293

Infrared optical properties of spinels. A study of the carrier of the 13, 17 and 32 mu m emission features observed in ISO-SWS spectra of oxygen-rich AGB stars  

NASA Astrophysics Data System (ADS)

In a previous paper, we have proposed magnesium aluminium spinel to be the carrier of the 13 and 17 mu m band features observed in the ISO spectra of some red giants. The IR optical properties of spinel strongly depend on its chemistry and its internal structure. To study the dependence of spinel's IR-spectra on its aluminium content, we have synthesized a number of crystals with different Al/Mg-ratios. Additionally, we performed an annealing experiment to investigate the phase transition between ordered and partially disordered spinel taking place at about 1200 K. We derived sets of optical constants of our natural, annealed and synthetic spinels in order to calculate the absorption efficiencies of small (sub-mu m-sized) spherical particles. Thereby, it turned out that natural as well as near-stoichiometric synthetic spinel can indeed be considered as a suitable candidate for the carrier of the 13 mu m feature observed in the spectra of some oxygen rich circumstellar shells. To illustrate this, we reinvestigated the mean profile of the residual dust emission in the 12-18 mu m wavelength range (i.e., in the so-called trough region between the two silicate bands). The reality of the emission feature at 16.8 mu m is confirmed by our new investigation. We demonstrated that it is not an instrumental artifact since it is not present in ISO spectra of K-stars. In the course of our laboratory work, we found a third prominent emissivity maximum of spinel at 32 mu m. This feature could also be detected in the spectra of the brightest 13 mu m band emission sources; we derived its mean band profile, too. The new sets of optical constants here presented have been made available for public access in the electronic database http://www.astro.uni-jena.de. Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, The Netherlands and the UK) and with the participation of ISAS and NASA.

Fabian, D.; Posch, Th.; Mutschke, H.; Kerschbaum, F.; Dorschner, J.

2001-07-01

294

Relativistic multi-configuration calculations of K{alpha} and K{beta} X-ray transitions for highly ionized Mo ions  

SciTech Connect

A relativistic multi-configuration Dirac-Fock technique has been used for computing the transition wavelengths, transition probabilities, absorption oscillator strengths, and line strengths for the K{alpha} and K{beta} line transitions of He-like to Ne-like molybdenum ions. The contributions from the Breit interaction, quantum electrodynamic corrections, and nuclear mass corrections to the initial and final levels have been taken into account. Transitions from the ground state to the n = 2 and 3 states of He-like and Li-like molybdenum have been calculated using two sets of configuration-interaction wavefunctions. One set of wavefunctions was generated using the fully relativistic GRASPVU code and the other was obtained using GRASP{sup 2}, the calculated transition wavelength, transition probabilities, and absorption strengths obtained by these two independent methods are in very good agreement and there is good agreement between these results and recent theoretical and experimental results. These data provide reference values for the level lifetimes, charge state distributions, and average charge of molybdenum plasmas.

Hao Lianghuan [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, Sichuan (China); Jiang Gang [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, Sichuan (China)], E-mail: haolianghuan_1983@163.com; Song Shuqiang; Hu Feng [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, Sichuan (China)

2008-09-15

295

Ab initio potential energy surfaces for both the ground (X (1)A') and excited (A (1)A") electronic states of HGeCl and the absorption and emission spectra of HGeCl/DGeCl.  

PubMed

Potential energy surfaces for the ground (X (1)A(')) and excited (A (1)A(")) electronic states of HGeCl and the transition dipole moment surface were obtained using an internally contracted multireference configuration interaction method with the Davidson correction and an augmented correlation-consistent polarized valence quadruple zeta basis set. Calculated vibrational energy levels of HGeCl and DGeCl on both the ground and excited electronic states are in excellent agreement with available experimental data. In addition, the absorption and emission spectra of both HGeCl and DGeCl were obtained using an efficient single Lanczos propagation method and the agreement with experimental spectra is also excellent. PMID:19045199

Lin, Sen; Xie, Daiqian; Guo, Hua

2008-10-21

296

Measurement of the 238U neutron-capture cross section and gamma-emission spectra from 10 eV to 100 keV using the DANCE detector at LANSCE  

SciTech Connect

A careful new measurement of the {sup 238}U(n,{gamma}) cross section from 10 eV to 100 keV has been made using the DANCE detector at LANSCE. DANCE is a 4{pi} calorimetric scintillator array consisting of 160 BaF{sub 2} crystals. Measurements were made on a 48 mg/cm{sup 2} depleted uranium target. The cross sections are in general good agreement with previous measurements. The gamma-ray emission spectra, as a function of gamma multiplicity, were also measured and compared to model calculations.

Ullmann, John L [Los Alamos National Laboratory; Couture, A J [Los Alamos National Laboratory; Keksis, A L [Los Alamos National Laboratory; Vieira, D J [Los Alamos National Laboratory; O' Donnell, J M [Los Alamos National Laboratory; Jandel, M [Los Alamos National Laboratory; Haight, R C [Los Alamos National Laboratory; Rundberg, R S [Los Alamos National Laboratory; Kawano, T [Los Alamos National Laboratory; Chyzh, A [NORTH CAROLINA STATE UNIV; Baramsai, B [NORTH CAROLINA STATE UNIV; Wu, C Y [LLNL; Mitchell, G E [NORTH CAROLINA STATE UNIV; Becker, J A [LLNL; Krticka, M [CHARLES UNIV

2010-01-01

297

A gas-tight Cu K alpha x-ray transparent reaction chamber for high-temperature x-ray diffraction analyses of halide gas/solid reactions.  

PubMed

An externally heated, x-ray transparent reaction chamber has been developed to enable the dynamic high temperature x-ray diffraction (HTXRD) analysis of a gas/solid [TiF(4)(g)/SiO(2)(s)] reaction involving a halide gas reactant formed at elevated temperatures (up to 350 degrees C) from a condensed source (TiF(4) powder) sealed within the chamber. The reaction chamber possessed x-ray transparent windows comprised of a thin (13 microm) internal layer of Al foil and a thicker (125 microm) external Kapton film. After sealing the SiO(2) specimens (diatom frustules or Stober spheres) above TiF(4) powder within the reaction chamber, the chamber was heated to a temperature in the range of 160-350 degrees C to allow for internal generation of TiF(4)(g). The TiF(4)(g) underwent a metathetic reaction with the SiO(2) specimen to yield a TiOF(2)(s) product. HTXRD analysis, using Cu K alpha x rays passed through the Kapton/Al windows of the chamber, was used to track the extent of SiO(2) consumption and/or TiOF(2) formation with time. The Al foil inner layer of the windows protected the Kapton film from chemical attack by TiF(4)(g), whereas the thicker, more transparent Kapton film provided the mechanical strength needed to contain this gas. By selecting an appropriate combination of x-ray transparent materials to endow such composite windows with the required thermal, chemical, and mechanical performance, this inexpensive reaction chamber design may be applied to the HTXRD analyses of a variety of gas/solid reactions. PMID:19947758

Shian, Samuel; Sandhage, Kenneth H

2009-11-01

298

Studies of electronic configurations in the emission spectra of lanthanides and actinides: application to the interpretation of Es I and Es II, predictions for Fm I  

SciTech Connect

The interpretation of the spectra of free atoms and gaseous ions in the 4f{sup N} and 5f{sup N} periods became less active after critical compilations of energy levels appeared. However, several spectra are still under study and the application of the Racah-Slater and HFR methods to extended sets of configurations leads to revisions and additions. In doubly charged ions of lanthanides, the treatment of configuration interaction by means of effective parameters and by extension of the basis of states are both important. Concerning actinides, calculations of several observables (Lande factors and isotope shifts in Pu I, hyperfine constants, transition probabilities) prove the quality of eigenfunctions. The classification of Es I and Es II has been extended and radial parameters for fine and hyperfine structures have been derived. Level predictions for the next element fermium are supported by parameter extrapolations.

Wyart, Jean-Francois [Laboratoire Aime Cotton, CNRS, Batiment 505, Centre Universitaire, FR-91405 Orsay Cedex (France)]. E-mail: jean-francois.wyart@lac.u-psud.fr; Blaise, Jean [Laboratoire Aime Cotton, CNRS, Batiment 505, Centre Universitaire, FR-91405 Orsay Cedex (France); Worden, Earl F. [Physics and Advanced Technologies Directorate, Lawrence Livermore National Laboratory, L-044, Livermore, CA 94550 (United States)

2005-02-15

299

Atomic Spectra  

NSDL National Science Digital Library

This page from Hyperphysics contains images depicting the light emitted by several elements and their respective spectra. The page also provides a description of how the size of a holographic image scales with the wavelength of the light used to observe it.

Nave, Carl R.

2010-03-12

300

Finely resolved transmission spectra and band structure of two-dimensional photonic crystals using emission from InAs quantum dots  

Microsoft Academic Search

We present continuous near-infared transmission measurements of two-dimensional photonic crystals etched through a (Ga,Al)As waveguide. We use photoluminescence of InAs self-organized quantum dots as an internal source with a broad guided spectrum. Transmission spectra exhibit both a marked gap for the TE polarization and a fine structure consisting of transmission oscillations around it. This fine structure is exploited to assess

D. Labilloy; H. Benisty; C. Weisbuch; C. J. M. Smith; T. F. Krauss; R. Houdr; U. Oesterle

1999-01-01

301

Observation of ionization shifts in K-shell emission from short-pulse laser irradiated micro-dot targets  

NASA Astrophysics Data System (ADS)

X-ray Thomson scattering using short pulse laser generated intense line radiation has a great potential as a time-resolved temperature and density diagnostic for high-energy density states of matter. We present recent results characterizing Chlorine K-alpha and K-beta line emission obtained by irradiating Saran foil with 50 Terawatt laser pulses from the Callisto laser (Jupiter Laser Facility, Lawrence Livermore National Laboratory). Spectra from front and rear side emission are recorded simultaneously with high resolution HOPG spectrometers employing imaging plate detectors. Conversion efficiencies of laser pulse energy into x-ray line emission of several 10-5 are achieved and are maintained throughout up to 7 J of laser energy, thus constituting a short pulsed narrow band x-ray source of more than 10^11 photons. When the target size is reduced to 50 micrometer (``micro-dot'') a significant blue-shift of up to 5 eV is clearly observed. This can be attributed to higher ionization states of the target atoms indicating achievement of a high-temperature solid density state. This work was performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under Contract No. W-7405-ENG-48 and LDRD 05-ERI-003.

Neumayer, Paul; Kritcher, Andrea; Landen, Otto; Lee, Haeja; Offerman, Dustin; Shipton, Eric; Glenzer, Siegfried

2006-10-01

302

Fluorescence Spectra  

NSDL National Science Digital Library

This experiment uses the Tracker video analysis and modeling tool to explore the phenomenon of fluorescence and its application in fluorescent lamps. For each of five different visible spectra, students (a) observe the spectrum directly, (b) measure its brightness versus wavelength in Tracker, and (c) answer both qualitative and quantitative questions about it. The spectra include a fluorescent dye with laser and UV illumination, a mercury lamp and two fluorescent lamps, all with red and green laser spots added for easy calibration. For more information, see the AAPT presentation. The zip file includes the lab instructions, spectrum images and Tracker data files. This requires Tracker version 4.62 or higher. Tracker installers are available for Windows, Mac and Linux from ComPADRE or the Tracker web site (http://www.cabrillo.edu/~dbrown/tracker/).

Brown, Douglas

2012-01-17

303

A responsivity-based criterion for accurate calibration of FTIR emission spectra: identification of in-band low-responsivity wavenumbers.  

PubMed

Spectra measured by remote-sensing Fourier transform infrared spectrometers are often calibrated using two calibration sources. At wavenumbers where the absorption coefficient is large, air within the optical path of the instrument can absorb most calibration-source signal, resulting in extreme errors. In this paper, a criterion in terms of the instrument responsivity is used to identify such wavenumbers within the instrument bandwidth of two remote-sensing Fourier transform infrared spectrometers. Wavenumbers identified by the criterion are found to be correlated with strong absorption line-centers of water vapor. Advantages of using a responsivity-based criterion are demonstrated. PMID:21451618

Rowe, Penny M; Neshyba, Steven P; Cox, Christopher J; Walden, Von P

2011-03-28

304

Observation of high-N hydroxyl pure rotation lines in atmospheric emission spectra by the CIRRIS 1A Space Shuttle Experiment  

Microsoft Academic Search

Pure rotation line emissions from highly rotationally excited OH have been observed between 80 and 110 km tangent height under both nighttime and daytime quiescent conditions. Data were obtained using the cryogenic CIRRIS 1A interferometer, operated on the Space Shuttle. Transitions from OH(v=02, N??33) were identified between 400 and 1000 cm?1, corresponding to states with energies as high as 23000

D. R. Smith; W. A. M. Blumberg; R. M. Nadile; S. J. Lipson; E. R. Huppi; N. B. Wheeler; J. A. Dodd

1992-01-01

305

The observable effect of a photospheric component on GRB's prompt emission spectrum: peak energy clustering and flat spectra above the thermal peak  

Microsoft Academic Search

A thermal radiative component is likely to accompany the first stages of the prompt emission of Gamma-ray bursts (GRB's) and X-ray flashes (XRF's). We study the properties of plasmas containing a low energy thermal photon component at comoving temperature theta ? kT ' \\/ mec2 ~ 10-5 - 10-2 interacting with an energetic electron component. We show that, for scattering

Asaf Pe'Er; Peter Mszros; Martin J. Rees

2006-01-01

306

The observable effect of a photospheric component on GRBs prompt emission spectrum: peak energy clustering and flat spectra above the thermal peak  

Microsoft Academic Search

A thermal radiative component is likely to accompany the first stages of the prompt emission of Gamma-ray bursts (GRBs) and X-ray flashes (XRFs). We study the properties of plasmas containing a low energy thermal photon component at comoving temperature ? ? kT ? \\/ mec2 ? 10?5 10?2 interacting with an energetic electron component. We show that, for scattering

Asaf Peer; Peter Meszaros; Martin J. Rees

2006-01-01

307

Fluorescence-Excitation and Emission Spectra from LH2 Antenna Complexes of Rhodopseudomonas acidophila as a Function of the Sample Preparation Conditions.  

PubMed

The high sensitivity of optical spectra of pigment-protein complexes to temperature and pressure is well known. In the present study, we have demonstrated the significant influence of the environments commonly used in bulk and single-molecule spectroscopic studies at low temperatures on the LH2 photosynthetic antenna complex from Rhodopseudomonas acidophila . A transfer of this LH2 complex from a bulk-buffer solution into a spin-coated polymer film results in a 189 cm(-1) blue shift of the B850 excitonic absorption band at 5 K. Within the molecular exciton model, the origin of this shift could be disentangled into three parts, namely to an increase of the local site energies, a contraction of the exciton band, and a decrease of the displacement energy. PMID:24033126

Kunz, Ralf; Timpmann, Ku; Southall, June; Cogdell, Richard J; Khler, Jrgen; Freiberg, Arvi

2013-09-27

308

Exploratory analysis of excitation-emission matrix fluorescence spectra with self-organizing maps as a basis for determination of organic matter removal efficiency at water treatment works  

NASA Astrophysics Data System (ADS)

In the paper, the self-organizing map (SOM) was employed for the exploratory analysis of fluorescence excitation-emission data characterizing organic matter removal efficiency at 16 water treatment works in the UK. Fluorescence spectroscopy was used to assess organic matter removal efficiency between raw and partially treated (clarified) water to provide an indication of the potential for disinfection by-products formation. Fluorescence spectroscopy was utilized to evaluate quantitative and qualitative properties of organic matter removal. However, the substantial amount of fluorescence data generated impeded the interpretation process. Therefore a robust SOM technique was used to examine the fluorescence data and to reveal patterns in data distribution and correlations between organic matter properties and fluorescence variables. It was found that the SOM provided a good discrimination between water treatment sites on the base of spectral properties of organic matter. The distances between the units of the SOM map were indicative of the similarity of the fluorescence samples and thus demonstrated the relative changes in organic matter content between raw and clarified water. The higher efficiency of organic matter removal was demonstrated for the larger distances between raw and clarified samples on the map. It was also shown that organic matter removal was highly dependent on the raw water fluorescence properties, with higher efficiencies for higher emission wavelengths in visible and UV humic-like fluorescence centers.

Bieroza, Magdalena; Baker, Andy; Bridgeman, John

2009-12-01

309

Analysis of the absorption spectra of gas emission of patients with lung cancer and chronic obstructive pulmonary disease by laser optoacoustic spectroscopy  

NASA Astrophysics Data System (ADS)

It is important to identify patients with chronic obstructive pulmonary disease (COPD) and lung cancer in the early stages of the disease. The method of laser opto-acoustic gas analysis, in this case, can act as a promising tool for diagnostics. The material for this study were the gas emission samples collected from patients and healthy volunteers - samples of exhaled air, swabs from teeth and cheeks. A set of material was formed three groups: healthy volunteers, patients with COPD, lung cancer patients. The resulting samples were analyzed by means of laser opto-acoustic gas analyzers: with intracavity location detector (ILPA-1), with extracavity location detector (LGA-2). Presentation of the results in an easy to visual form was performed using the method of elastic maps, based on the principal component analysis. The results of analysis show potentialities of usage of laser optoacoustic spectroscopy application to assess the status of patients with chronic obstructive pulmonary disease and lung cancer.

Bukreeva, Ekaterina B.; Bulanova, Anna A.; Kistenev, Yurii V.; Kuzmin, Dmitry A.; Tuzikov, Sergei A.; Yumov, Evgenii L.

2013-02-01

310

X-ray emission following K-L double ionization by electron impact and K capture: Vacancy-production probabilities and structure of the K? satellite spectra  

NASA Astrophysics Data System (ADS)

K? x-ray satellites following K-electron capture in 55Fe and electron impact on Mn have been measured with a high-resolution spectrometer. Ratios of double- to single-vacancy-production probability are found to be PKL=(2.5+/-0.5)10-3 and (9.5+/-0.9)10-3 for capture and impact, respectively. An evaluation of vacancy rearrangement in the L shell before satellite emission has been carried out with the use of published level widths. It is found that in electron impact, as distinct from K capture, essentially only satellites associated with a 2p spectator vacancy are observed. This observation is at variance with certain commonly used satellite assignments. Energies and intensities of the satellite transitions have been calculated in intermediate coupling and coordinations are proposed for the stronger lines.

Li-Scholz, Angela; Leiberich, A.; Scholz, W.

1982-12-01

311

Intraoperative detection of 18F-FDG-avid tissue sites using the increased probe counting efficiency of the K-alpha probe design and variance-based statistical analysis with the three-sigma criteria  

PubMed Central

Background Intraoperative detection of 18F-FDG-avid tissue sites during 18F-FDG-directed surgery can be very challenging when utilizing gamma detection probes that rely on a fixed target-to-background (T/B) ratio (ratiometric threshold) for determination of probe positivity. The purpose of our study was to evaluate the counting efficiency and the success rate of in situ intraoperative detection of 18F-FDG-avid tissue sites (using the three-sigma statistical threshold criteria method and the ratiometric threshold criteria method) for three different gamma detection probe systems. Methods Of 58 patients undergoing 18F-FDG-directed surgery for known or suspected malignancy using gamma detection probes, we identified nine 18F-FDG-avid tissue sites (from amongst seven patients) that were seen on same-day preoperative diagnostic PET/CT imaging, and for which each 18F-FDG-avid tissue site underwent attempted in situ intraoperative detection concurrently using three gamma detection probe systems (K-alpha probe, and two commercially-available PET-probe systems), and then were subsequently surgical excised. Results The mean relative probe counting efficiency ratio was 6.9 ( 4.4, range 2.215.4) for the K-alpha probe, as compared to 1.5 ( 0.3, range 1.02.1) and 1.0 ( 0, range 1.01.0), respectively, for two commercially-available PET-probe systems (P?K-alpha probe (P?=?0.05). Conclusions Our results suggest that the improved probe counting efficiency of the K-alpha probe design used in conjunction with the three-sigma statistical threshold criteria method can allow for improved detection of 18F-FDG-avid tissue sites when a low in situ T/B ratio is encountered.

2013-01-01

312

Excitonic emission from CsI(Na)  

Microsoft Academic Search

Photoluminescence in CsI(Na) was studied. This work used nonionizing light sources and obtained the data from well-annealed zone-refined specimens. A series of excitation and emission spectra were measured at temperatures between 300 and 4.2K. The emission spectra consist of the characteristic blue emission and other low-temperature emissions. The emission spectra were decomposed into the superposition of Gaussian peaks by computer.

Olive Lee Hsu; Clayton W. Bates Jr.

1977-01-01

313

The Resolved Fe K alpha Line of the Broad-Line Radio Galaxy 3C 390.3 and Its Implications  

Microsoft Academic Search

We present the results of X-ray observations of the broad-line radio galaxy 3C 390.3 obtained with ASCA The 0.5-10 keV spectrum of the source is well described by a power-law model plus a component arising from Compton reflection and an emission line. There is no evidence for a soft excess. The photon index is 1.70 + 0.04, and the absorbing

Michael Eracleous; Jules P. Halpern; Mario Livio

1996-01-01

314

Longitudinal mode spectra of diode lasers  

SciTech Connect

A theory is presented which explains the longitudinal mode spectra of diode lasers. The theory is based on spontaneous emission coupling into the longitudinal modes and the excellent agreement with experimental data for both gain guided and real refractive index waveguide diode lasers is obtained because of the more accurate and detailed modeling of the spontaneous emission coupling and the laser itself.

Streifer, W.; Scifres, D.R.; Burnham, R.D.

1982-02-15

315

Beta Spectra. II-Positron Spectra.  

National Technical Information Service (NTIS)

Using the Fermi theory of beta decay, the beta spectra for 30 positron emitters have been computed, introducing a correction factor for unique forbidden transitions. The spectra are ploted vs. energy, once normalised, and tabulated with the related Fermi ...

A. Grau E. Garcia-Torano

1981-01-01

316

High K-alpha X-ray Conversion Efficiency From Extended Source Gas Jet Targets Irradiated by Ultra Short Laser Pulses  

SciTech Connect

The absolute laser conversion efficiency to K{sub {alpha}}-like inner shell x-rays (integrated from K{sub {alpha}} to K{sub {beta}}) is observed to be an order of magnitude higher in argon gas jets than in solid targets due to enhanced emission from higher ionization stages following ultra short pulse laser irradiation. Excluding the higher ionization stages, the conversion efficiency to near-cold K{sub {alpha}} is the same in gas jets as in solid targets. These results demonstrate that gas jet targets are bright, high conversion efficiency, high repetition rate, debris-free multi-keV x-ray sources for spectrally resolved scattering and backlighting of rapidly evolving dense matter.

Kugland, N L; Constantin, C; Collette, A; Dewald, E; Froula, D; Glenzer, S H; Kritcher, A; Neumayer, P; Ross, J S; Niemann, C

2007-11-01

317

SPECTRAL DECONVOLUTION OF FLUORESCENCE SPECTRA FROM PLANT EXTRACTS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Fluorescence emission spectra have been observed to yield information pertaining to the identification of plant species. One approach to acquiring these characteristic spectra has been to record the spectral signature resulting from an extract of the plant. Often these spectra have been overwhelme...

318

THE SPECTRA OF THE DOUBLY AND TRIPLY IONIZED RARE EARTHS  

Microsoft Academic Search

The present status of the knowledge of the structure of the spectra of ; the doubly and triply ionized spectra of the rare earths is derived partly from ; experimental data of the emission spectra of the free ions which provide the ; energy level scheme in great detail but are difficuit and laborious to analyze. ; For the lower

G. H. Dieke; H. M. Crosswhite

1963-01-01

319

Spectra Optia Apheresis System  

Center for Biologics Evaluation and Research (CBER)

... Spectra Optia Apheresis System. Applicant: Terumo BCT, Inc. 510(k) number: BK120076. Product: Spectra Optia Apheresis System. ... More results from www.fda.gov/biologicsbloodvaccines/bloodbloodproducts/approvedproducts

320

Cosmology from quasar spectra  

NASA Astrophysics Data System (ADS)

High resolution spectroscopy of high redshift quasar spectra enables us to investigate the properties of the intergalactic medium (IGM) and measure cosmological parameters from the Lya forest. Toward high precision cosmology, this dissertation presents the following four topics. (1) Principal Component Analysis (PCA) on quasar spectrum: We introduce the PCA to describe quasar emission lines and continua quantitatively, and we attempt to make a prediction of the continuum shape in the Lya forest using wavelengths redward of Lya emission. (2) Flux calibration of Keck HIRES data: On our way to achieve high accuracy measurement, it was necessary to develop new calibration schemes and explore the origin of systematic errors. My contribution includes the following and is discussed throughout the thesis: (i) the development of the flux calibration scheme, (ii) the discovery of three emission lines in the Lya forest, (iii) the establishment of high resolution standard star spectra, and (iv) the identification of ozone lines in the spectrum. (3) D/H measurement: We present precise measurements of the primordial deuterium to hydrogen ratio (D/ H) toward two quasars, HS0105+1619 and Q1243+3047, which constrains the baryon to photon ratio e = 5.9 +/- 0.5 x 10 -10 or the baryon density O b h 2 = 0.0214 +/- 0.0020 via the Big Bang Nucleosynthesis theory. (4) Studies of the Lya forest at z ~ 2: We also present the measurements of the total amount of neutral hydrogen absorption in the IGM. We compare our observed data with hydrodynamic simulations and find good agreement when we use the following cosmological parameters: H o = 71 kin s -1 Mpc -1 , O L = 0.73, O m = 0.27, O b = 0.044, the amplitude of the power spectrum s 8 = 0.9, and the photoinization rate G 912 = (1.44 +/- 0.11) x 10 -12 s -1 . We conclude that the measurements of the cosmological parameters from our primordial D/H measurements, recent WMAP satellite observation of the cosmic microwave background, and our the total amount of neutral hydrogen in the IGM at z ~ 2 are in a concordance with the LCDM model.

Suzuki, Nao

2005-11-01

321

Molecular detectability in exoplanetary emission spectra  

NASA Astrophysics Data System (ADS)

Of the many recently discovered worlds orbiting distant stars, very little is yet known of their chemical composition. With the arrival of new transit spectroscopy and direct imaging facilities, the question of molecular detectability as a function of signal-to-noise (SNR), spectral resolving power and type of planets has become critical. In this paper, we study the detectability of key molecules in the atmospheres of a range of planet types, and report on the minimum detectable abundances at fixed spectral resolving power and SNR. The planet types consideredhot Jupiters, hot super-Earths, warm Neptunes, temperate Jupiters and temperate super-Earthscover most of the exoplanets characterisable today or in the near future. We focus on key atmospheric molecules, such as CH4, CO, CO2, NH3, H2O, C2H2, C2H6, HCN, H2S and PH3. We use two methods to assess the detectability of these molecules: a simple measurement of the deviation of the signal from the continuum, and an estimate of the level of confidence of a detection through the use of the likelihood ratio test over the whole spectrum (from 1 to 16 ?m). We find that for most planetary cases, SNR = 5 at resolution R = 300 (? < 5 ?m) and R = 30 (? > 5 ?m) is enough to detect the very strongest spectral features for the most abundant molecules, whereas an SNR comprised between 10 and 20 can reveal most molecules with abundances 10?6 or lower, often at multiple wavelengths. We test the robustness of our results by exploring sensitivity to parameters such as vertical thermal profile, mean molecular weight of the atmosphere and relative water abundances. We find that our main conclusions remain valid except for the most extreme cases. Our analysis shows that the detectability of key molecules in the atmospheres of a variety of exoplanet cases is within realistic reach, even with low SNR and spectral resolving power.

Tessenyi, M.; Tinetti, G.; Savini, G.; Pascale, E.

2013-11-01

322

M - and L -shell ionization in near-central collisions of 5. 5-MeV/amu sup 16 O ions with Mo atoms deduced from theoretical analysis of high-resolution K x-ray spectra  

SciTech Connect

The {ital K}{alpha} and {ital K}{beta} x-ray spectra of molybdenum bombarded by 5.5-MeV/amu {sup 16}O ions were measured with high resolution. In such heavy-ion--atom collisions, multiple ionization of the {ital M} and {ital L} shells of the target atoms is extremely likely to occur, resulting in a complex structure of the observed spectra. The {ital L}{sup {ital n}}-satellite structure was resolved, whereas {ital M} vacancies produce only a shift and a broadening of the lines so that it is not possible to obtain in a direct way information about the {ital M}-hole distribution. We thus propose a method for the analysis of x-ray spectra of multiply ionized atoms. In this method the measured {ital K}{alpha} and {ital K}{beta} spectra are simultaneously analyzed as a sum of {ital K}{alpha}{ital L}{sup {ital n}M{ital m}} and {ital K}{beta}{ital L}{sup {ital n}M{ital m}} components, respectively, with theoretically determined profiles. A binomial distribution of holes in the {ital M} shell is assumed and the {ital M}-shell ionization probabilities are treated as adjustable parameters. The profiles are constructed as sums of Voigt functions, whose positions and heights are determined by extensive multiconfiguration Dirac-Fock method calculations. If, in a simultaneous fit to the {ital K}{alpha}{ital L}{sup 0} and {ital K}{beta}{sub 1,3}{ital L}{sup 0} lines, just one parameter {ital p}{sub {ital M}}{sup {ital X}} describing the {ital M}-shell ionization at the moment of the {ital K} x-ray transition is used, the experimental data are not reproduced in an entirely satisfactory way ({ital p}{sub {ital M}}{sup {ital X}}=0.19{plus minus}0.02).

Carlen, M.W.; Polasik, M.; Boschung, B.; Dousse, J.; Gasser, M.; Halabuka, Z.; Hoszowska, J.; Kern, J.; Perny, B.; Rheme, C. (Physics Department, University of Fribourg, CH-1700 Fribourg (Switzerland)); Rymuza, P.; Sujkowski, Z. (Institute for Nuclear Studies, 05-400 Swierk (Poland))

1992-10-01

323

Performances of a bent-crystal spectrometer adapted to resonant x-ray emission measurements on gas-phase samples  

SciTech Connect

We describe a bent-crystal spectrometer adapted to measure x-ray emission resulting from core-level excitation of gas-phase molecules in the 0.8-8 keV energy range. The spectrometer is based on the Johann principle, and uses a microfocused photon beam to provide high-resolution (resolving power of {approx}7500). A gas cell was designed to hold a high-pressure (300 mbar) sample of gas while maintaining a high vacuum (10{sup -9} mbar) in the chamber. The cell was designed to optimize the counting rate (2000 cts/s at the maximum of the Cl K{alpha} emission line), while minimizing self-absorption. Example of the K{alpha} emission lines of CH{sub 3}Cl molecules is presented to illustrate the capabilities of this new instrument.

Journel, Loiec; El Khoury, Lara; Marin, Thierry; Guillemin, Renaud; Carniato, Stephane; Avila, Antoine; Delaunay, Renaud; Hague, Coryn F.; Simon, Marc [Laboratoire de Chimie Physique-Matiere et Rayonnement, UPMC University of Paris 06, UMR 7614, F-75005 Paris (France) and Laboratoire de Chimie Physique-Matiere et Rayonnement, CNRS, UMR 7614, F-75005 Paris (France)

2009-09-15

324

EXPANSION VELOCITY OF EJECTA IN TYCHO's SUPERNOVA REMNANT MEASURED BY DOPPLER BROADENED X-RAY LINE EMISSION  

SciTech Connect

We show that the expansion of ejecta in Tycho's supernova remnant (SNR) is consistent with a spherically symmetric shell, based on Suzaku measurements of the Doppler broadened X-ray emission lines. All of the strong K{alpha} line emissions show broader widths at the center than at the rim, while the centroid energies are constant across the remnant (except for Ca). This is the pattern expected for Doppler broadening due to expansion of the SNR ejecta in a spherical shell. To determine the expansion velocities of the ejecta, we applied a model for each emission-line feature having two Gaussian components separately representing red- and blueshifted gas, and inferred the Doppler velocity difference between these two components directly from the fitted centroid energy difference. Taking into account the effect of projecting a three-dimensional shell to the plane of the detector, we derived average spherical expansion velocities independently for the K{alpha} emission of Si, S, Ar, and Fe, and K{beta} of Si. We found that the expansion velocities of Si, S, and Ar ejecta of 4700 {+-} 100 km s{sup -1} are distinctly higher than that obtained from Fe K{alpha} emission, 4000 {+-} 300 km s{sup -1}, which is consistent with segregation of the Fe in the inner ejecta. Combining the observed ejecta velocities with the ejecta proper-motion measurements by Chandra, we derived a distance to Tycho's SNR of 4 {+-} 1 kpc.

Hayato, Asami; Yamaguchi, Hiroya; Tamagawa, Toru; Makishima, Kazuo [RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Katsuda, Satoru; Hwang, Una [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Hughes, John P. [Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, NJ 08854-8019 (United States); Ozawa, Midori [Department of Physics, Graduate School of Science, Kyoto University, Kita-Shirakawa, Sakyo-ku, Kyoto 606-8502 (Japan); Bamba, Aya [School of Cosmic Physics, Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2 (Ireland); Kinugasa, Kenzo [Gunma Astronomical Observatory, 6860-86, Nakayama, Takayama-mura, Agatsuma-gun, Gunma 377-0702 (Japan); Terada, Yukikatsu [Department of Physics, Saitama University, Shimo-Okubo 255, Sakura, Saitama 338-8570 (Japan); Furuzawa, Akihiro; Kunieda, Hideyo, E-mail: asami.hayato@nasa.go [Division of Particle and Astrophysical Science, Graduate School of Science, Nagoya University, Furo-cho, Nagoya 464-8602 (Japan)

2010-12-10

325

Near-infrared spectra of cataclysmic variables  

NASA Astrophysics Data System (ADS)

We present results from the first systematic survey of the near-infrared (1-2.5 microns) spectra of cataclysmic variables. Emission lines of H I and He I are present in most objects. He II emission is observed in V Sge. Lines from high-ionization species may be present in TT Ari and SS Cyg. Absorption features typical of late-type stars are detected in some systems. Spectra of SS Cyg over several years show possible variability of the absorption line strengths. On some occasions the absorption lines in SS Cyg may be stronger than those expected from a K5 V star.

Ramseyer, Tod F.; Dinerstein, Harriet L.; Lester, D. F.; Provencal, J.

1993-09-01

326

IRAS low-resolution spectra of galaxies  

SciTech Connect

The spectra of external galaxies are selected and extracted from the IRAS LRS database. Twenty-one objects present viable spectra. One is a peculiar star-forming E-S0 galaxy. The remainder are all starburst or H II region galaxies. Their average spectrum demonstrates the importance of the PAH emission bands in the 8-23-micron region and reinforces the conclusion reached from ground-based spectra, that there is a strong correlation between the PAH bands and the starburst or H II region character of a galaxy. 32 refs.

Cohen, M.; Volk, K. (Jamieson Science and Engineering, Inc., Scotts Valley (USA) California Univ., Berkeley (USA) NASA, Ames Research Center, Moffett Field (USA) SETI Institute, Mountain View, CA (USA))

1989-11-01

327

Corrected fluorescence spectra of fulvic acids isolated from soil and water  

Microsoft Academic Search

The fluorescence of humic matter is a ubiquitous phenomenon that occurs for isolated soil and aquatic matter and for natural water samples. This property is used to compare humic substances, but uncorrected emission spectra can be especially misleading for spectra taken on different instruments. This paper details the corrections of emission fluorescence spectra of well-characterized fulvic acids isolated from soil

Marc Ewald; Colette Belin; Pierrette Berger; James H. Weber

1983-01-01

328

New LRS spectra for 356 bright IRAS sources  

SciTech Connect

The low-resolution spectra of all IRAS point sources with F(nu) (12 microns) greater than 40 Jy that were not included in the Atlas of Low-Resolution Spectra are presented. These have been classified into eight groups based upon the spectral morphology. Silicate emission spectra and red-continuum spectra associated with H II region sources form about 60 percent of this sample. All types of spectra in the LRS Atlas are represented in the sample except for emission-line sources. The spectra is used to test a recent classification scheme for IRAS sources based on broadband colors. The spectra are consistent with the classifications from the colors in most cases. 20 refs.

Volk, K.; Cohen, M. (SETI Institute, Mountain View, CA (USA); California Univ., Berkeley (USA); Jamieson Science and Engineering, Inc., Scotts Valley, CA (USA))

1989-09-01

329

Mineralogy of Martian atmospheric dust inferred from thermal infrared spectra of aerosols  

Microsoft Academic Search

We have utilized optical constants derived from thermal infrared spectra acquired by the Mariner 9 Infrared Interferometer Spectrometer (M9 IRIS) and Mars Global Surveyor Thermal Emission Spectrometer (MGS TES), during periods of relatively high dust\\/low water ice opacity, to generate synthetic transmission and emission spectra of the atmospheric dust. Using libraries of transmission and emission spectra of common rock-forming minerals

Victoria E. Hamilton; Harry Y. McSween Jr; Bruce Hapke

2005-01-01

330

5-14 ?m Spitzer spectra of Themis family asteroids  

NASA Astrophysics Data System (ADS)

We present 5-14 ?m spectra of 8 Themis family asteroids observed with Spitzer. The diameter and geometric albedo are determined using the NEATM model. Their emissivity spectra is studied in order to determine if they exhibit an emission plateau at about 9 to 12 ?m as observed in other primitive asteroids of the outer belt, attributed to fine silicates (the Si-O stretch fundamental).

Al-Lagoa, V.; Licandro, J.; Campins, H.; Hardgrove, K.; Fernndez, Y.; Kelley, M. S.; Rivkin, A.; Ziffer, J.

2011-10-01

331

Resonant Compton scattering and gamma-ray burst continuum spectra  

NASA Astrophysics Data System (ADS)

The Thomson limit of resonant inverse Compton scattering in the strong magnetic fields of neutron stars is considered as a mechanism for producing gamma-ray burst continuum spectra. Photon production spectra and electron cooling rates are presented using the full magnetic Thomson cross-section. Model emission spectra are obtained as self-consistent solutions of a set of photon and electron kinetic equations, displaying spectral breaks and other structure at gamma-ray energies.

Baring, M. G.

1995-05-01

332

Luminescence Spectra of Laser-induced Cavitation Bubbles  

Microsoft Academic Search

The luminescence spectra of laser-induced cavitation bubbles near rigid boundaries are measured for various relative distances between the bubble and the boundaries. We find that the luminescence spectra of bubbles collapsing near a single boundary consist of only a blackbody continuum. Luminescence from bubbles collapsing between two parallel rigid boundaries also contains OH* emission bands similar to those found in

Emil A. Brujan

2005-01-01

333

Radio Spectra and Star Formation Histories in HII Galaxies  

Microsoft Academic Search

A sample of HII galaxies has been observed in several radio and optical bands. These galaxies are undergoing very active star formation; they have been selected on the basis of strong radio continuum emission. Radio continuum observations were obtained to determine their radio spectra. Several of the spectra were found to flatten towards lower frequencies, which is unusual. Surface and

Hans-Jorg Deeg

1993-01-01

334

Libraries of Stellar Spectra  

NSDL National Science Digital Library

This is a guide to online and abstract libraries of stellar spectra. This reference list also includes information about the spectra of Late-M, L, and T Dwarf stars, Morgan-Keenan spectral classification, the solar spectrum, spectrophotometric atlases, and automated and neural network classification.

2005-04-25

335

Spectra from Space  

NSDL National Science Digital Library

This site from the Exploratorium provides information on telescopes and observatories such as the Hubble Space Telescope that are being used to study spectra from space. Gamma-ray, x-ray, ultraviolet, and infrared spectra are all examined. The purpose and discoveries made by each observatory are included along with related hands-on activities like a liquid crystal IR detector activity.

Felter, Neil

2006-07-20

336

Units of ring spectra and Thom spectra  

Microsoft Academic Search

We review and extend the theory of Thom spectra and the associated\\u000aobstruction theory for orientations. We recall (from May, Quinn, and Ray) that\\u000aa commutative ring spectrum A has a spectrum of units gl(A). To a map of\\u000aspectra f: b -> bgl(A), we associate a commutative A-algebra Thom spectrum Mf,\\u000awhich admits a commutative A-algebra map to R

Matthew Ando; Andrew J. Blumberg; David J. Gepner; Michael J. Hopkins; Charles Rezk

2008-01-01

337

Demonstrating Absorption Spectra Using Commercially Available Incandescent Light Bulbs  

Microsoft Academic Search

In introductory astronomy courses, I typically introduce the three types of spectra: continuous, absorption line, and emission line. It is standard practice to use an ordinary incandescent light bulb to demonstrate the production of a continuous spectrum, and gas discharge tubes to demonstrate the production of an emission line spectrum. The concept of an absorption spectrum is more difficult for

Jennifer J. Birriel

2008-01-01

338

Line-core and line-wing features in the temperature-dependent Mg(3s3p-3s^2)-He(1s^2) emission/absorption spectra  

NASA Astrophysics Data System (ADS)

The present study deals with the collisional broadening of the monoatomic magnesium, evolving in a helium gas, in the wavelength and temperature ranges 260-310 nm and 100-3000 K, respectively. The spectral profiles, generated from our theoretical computations, are based on the most recent potential energy curves and transition dipole moments. The purpose of this treatment is twofold. First, using the Baranger impact approximation, the width and shift of the line core of the spectra are determined and their variation law with temperature is examined. The obtained results agree quite well with those already published. Then, the satellite structures in the blue and red wings are analyzed quantum mechanically. The calculations show especially that the free-free transitions are the most contributive in the MgHe photoabsorption spectra and a satellite structure is observable beyond the temperature 2000 K around the wavelength 274 nm.

Bouledroua, Moncef; Reggami, Lamia

2010-03-01

339

K-Shell Diagram and Hypersatellite Spectra of 4D Transition Elements  

SciTech Connect

The K-shell diagram (K{alpha}{sub 1,2} and K{beta}{sub 1,3}) and hypersatellite (HS) (K{sup h}{alpha}{sub 1,2}) spectra of Y, Zr, Mo, and Pd have been measured with high energy-resolution using photoexcitation by 90 keV synchrotron radiation. Comparison of the measured and ab initio calculated HS spectra demonstrates the importance of quantum electrodynamical (QED) effects for the HS spectra. Phenomenological fits of the measured spectra by Voigt functions yield accurate values for the shift of the HS from the diagram lines, the splitting of the HS lines, and their intensity ratio. Good agreement with theory was found for all quantities except for the intensity ratio, which is dominated by the intermediacy of the coupling of the angular momenta. The observed deviations imply that our current understanding of the variation of the coupling scheme from LS to jj across the periodic table may require some revision.

Diamant, R.; Kao, C.; Huotari, S.; Hamalainen, K.; Sharon, R.; Honkimaki, V.; Buslaps, T.; Deutsch, M.

2009-07-25

340

Thermal infrared emission spectroscopy of anhydrous  

Microsoft Academic Search

The objective of this study is to present the thermal emission spectra of various anhydrous, calcite- and dolomite-series carbonate minerals to illustrate the effect of the structural cation (Ca 2+, Mg 2+, Fe 2+, Mn 2+, Zn 2+) on shifting the positions of the carbonate absorption bands. All of the carbonate mineral emission spectra included in this study exhibit three

Philip R. Christensen

1997-01-01

341

Stimulated emission from semiconductor microcavities  

SciTech Connect

Laser-like emissions from semiconductor microcavities at low temperature have attracted considerable attention recently because of the possibility of realizing a non-equilibrium condensate by using cavity-polaritons. In this paper the authors present experimental studies of optical properties of a microcavity near the lasing threshold. They show that the minimum lasing threshold is achieved when the cavity is tuned significantly below the exciton line center. By comparing emission spectra with reflectivity spectra, they also show that well-resolved doublet in the emission spectra near the lasing threshold are not associated with cavity-polaritons. These results suggest that laser-like emissions form the microcavity are due to conventional stimulated emission processes with exciton localization playing a significant role.

Fan, X.; Wang, H. [Univ. of Oregon, Eugene, OR (United States). Dept. of Physics; Hou, H.Q.; Hammons, B.E. [Sandia National Labs., Albuquerque, NM (United States)

1997-04-01

342

Background estimation in experimental spectra  

SciTech Connect

A general probabilistic technique for estimating background contributions to measured spectra is presented. A Bayesian model is used to capture the defining characteristics of the problem, namely, that the background is smoother than the signal. The signal is allowed to have positive and/or negative components. The background is represented in terms of a cubic spline basis. A variable degree of smoothness of the background is attained by allowing the number of knots and the knot positions to be adaptively chosen on the basis of the data. The fully Bayesian approach taken provides a natural way to handle knot adaptivity and allows uncertainties in the background to be estimated. Our technique is demonstrated on a particle induced x-ray emission spectrum from a geological sample and an Auger spectrum from iron, which contains signals with both positive and negative components. (c) 2000 The American Physical Society.

Fischer, R. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association D-85740 Garching bei Muenchen, (Germany); Hanson, K. M. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association D-85740 Garching bei Muenchen, (Germany); Los Alamos National Laboratory, MS P940, Los Alamos, New Mexico 87545 (United States); Dose, V. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association D-85740 Garching bei Muenchen (Germany); Linden, W. von der [Institut fuer Theoretische Physik, Technische Universitaet Graz, Petersgasse 16, A-8010 Graz, (Austria)

2000-02-01

343

Computational Study of Emitted Spectra from the Neon Plasma Focus  

NASA Astrophysics Data System (ADS)

The expected emission spectra (full, Bremsstrahlung, recombination, and line) of neon focussed plasma have been studied for different conditions. Expected neon plasma spectra at certain electron temperature range have been plotted. The suitable electron temperatures ranges for neon plasma soft X-ray emission and extreme ultraviolet emission have been investigated. The X-ray ratio curves for various electron temperatures with probable electron and ion densities of the neon plasma produced have been computed with the assumption of non-local thermodynamic equilibrium model for the distribution of the ionic species. These ratio curves could be used for electron temperatures deduction of neon plasma focus.

Akel, M.; Alsheikh Salo, S.; Wong, C. S.

2013-08-01

344

[Experimental study on spectra of compressed air microwave plasma].  

PubMed

Using a microwave plasma generator, compressed air microwave plasma was excited under 1 - 5 atm pressures. Under different pressures and different incident microwave power, the emission spectra of compressed air microwave plasma were studied with a spectra measuring system. The results show that continuum is significant at atmospheric pressure and the characteristic will be weakened as the pressure increases. The band spectra intensity will be reduced with the falling of the incident microwave power and the band spectra were still significant. The experimental results are valuable to studying the characteristics of compressed air microwave plasma and the generating conditions of NO active groups. PMID:23705456

Liu, Yong-Xi; Zhang, Gui-Xin; Wang, Qiang; Hou, Ling-Yun

2013-03-01

345

Incoherent radar spectra  

Microsoft Academic Search

General expressions for the incoherent scatter spectra are presented. These are relevant for the UHF radar in the monostatic backscatter case (thus excluding only the effect of the magnetic field), based on the Nyquist approach.

Matti K. Vallinkoski

1987-01-01

346

Thermodynamic analysis of spectra  

SciTech Connect

Although random matrix theory had its initial application to neutron resonances, there is a relative scarcity of suitable nuclear data. The primary reason for this is the sensitivity of the standard measures used to evaluate spectra--the spectra must be essential pure (no state with a different symmetry) and complete (no states missing). Additional measures that are less sensitive to these experimental limitations are of significant value. The standard measure for long range order is the {delta}{sub 3} statistic. In the original paper that introduced this statistic, Dyson and Mehta also attempted to evaluate spectra with thermodynamic variables obtained from the circular orthogonal ensemble. We consider the thermodynamic 'internal energy' and evaluate its sensitivity to experimental limitations such as missing and spurious levels. Monte Carlo simulations suggest that the internal energy is less sensitive to mistakes than is {delta}{sub 3}, and thus the internal energy can serve as a addition to the tool kit for evaluating experimental spectra.

Mitchell, G. E. [North Carolina State University, Raleigh, NC 27695 and Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Shriner, J. F. Jr. [Tennessee Technological University, Cookeville, TN 38505 (United States)

2008-04-04

347

Spectra over complex terrain  

SciTech Connect

Spectra have been measured over land downwind of a water surface, over hilltops and escarpments, and over rolling farmland. The following hypotheses can be used to explain the differences between these spectra. (1) For wavelengths short compared to the fetch over the new terrain, spectral densities are in equilibrium with the new terrain. (2) For wavelengths long compared to this fetch, spectral densities remain unchanged if the ground is horizontal. If the flow is over a steep hill, the low-frequency structure is modified by distortion of the mean flow, with the longitudinal component losing energy relative to the lateral and vertical components. Because vertical-velocity spectra contain relatively less low-frequency energy than horizontal-velocity spectra, energetic vertical-velocity fluctuations tend to be in equilibrium with local terrain.

Panofsky, H.A.; Larko, D.; Lipschutz, R.; Stone, G.

1981-01-01

348

Cathodoluminescence spectra of gallium nitride nanorods  

PubMed Central

Gallium nitride [GaN] nanorods grown on a Si(111) substrate at 720C via plasma-assisted molecular beam epitaxy were studied by field-emission electron microscopy and cathodoluminescence [CL]. The surface topography and optical properties of the GaN nanorod cluster and single GaN nanorod were measured and discussed. The defect-related CL spectra of GaN nanorods and their dependence on temperature were investigated. The CL spectra along the length of the individual GaN nanorod were also studied. The results reveal that the 3.2-eV peak comes from the structural defect at the interface between the GaN nanorod and Si substrate. The surface state emission of the single GaN nanorod is stronger as the diameter of the GaN nanorod becomes smaller due to an increased surface-to-volume ratio.

2011-01-01

349

A DEEP CHANDRA ACIS STUDY OF NGC 4151. II. THE INNERMOST EMISSION LINE REGION AND STRONG EVIDENCE FOR RADIO JET-NLR CLOUD COLLISION  

SciTech Connect

We have studied the X-ray emission within the inner {approx}150 pc radius of NGC 4151 by constructing high spatial resolution emission line images of blended O VII, O VIII, and Ne IX. These maps show extended structures that are spatially correlated with the radio outflow and optical [O III] emission. We find strong evidence for jet-gas cloud interaction, including morphological correspondences with regions of X-ray enhancement, peaks of near-infrared [Fe II] emission, and optical clouds. In these regions, moreover, we find evidence of elevated Ne IX/O VII ratios; the X-ray emission of these regions also exceeds that expected from nuclear photoionization. Spectral fitting reveals the presence of a collisionally ionized component. The thermal energy of the hot gas suggests that {approx}> 0.1% of the estimated jet power is deposited into the host interstellar medium through interaction between the radio jet and the dense medium of the circumnuclear region. We find possible pressure equilibrium between the collisionally ionized hot gas and the photoionized line-emitting cool clouds. We also obtain constraints on the extended iron and silicon fluorescent emission. Both lines are spatially unresolved. The upper limit on the contribution of an extended emission region to the Fe K{alpha} emission is {approx}< 5% of the total, in disagreement with a previous claim that 65% of the Fe K{alpha} emission originates in the extended narrow line region.

Wang Junfeng; Fabbiano, Giuseppina; Elvis, Martin; Risaliti, Guido; Karovska, Margarita; Zezas, Andreas [Harvard-Smithsonian Center for Astrophysics, 60 Garden St, Cambridge, MA 02138 (United States); Mundell, Carole G., E-mail: juwang@cfa.harvard.edu [Astrophysics Research Institute, Liverpool John Moores University, Birkenhead CH41 1LD (United Kingdom)

2011-07-20

350

Discrimination of phytoplankton classes using characteristic spectra of 3D fluorescence spectra.  

PubMed

The discrimination of phytoplankton classes using the characteristic fluorescence spectra extracted from three-dimensional fluorescence spectra was investigated. Single species cultures of 11 phytoplankton species, representing 5 major phytoplankton divisions, were used. The 3D fluorescence spectra of the cultures grown at different temperatures (20 and 15 degrees C) and illumination intensities (140, 80 and 30 microM m(-2) s(-1)) were measured and their feature extraction methods were explored. Ordering Rayleigh and Raman scattering data as zero, the obtained excitation-emission matrices were processed by both singular value decomposition (SVD) and trilinear decomposition methods. The resulting first principal component can be regarded as the characteristic spectrum of the original 3D fluorescence spectrum. The analysis shows that such characteristic spectra have a discriminatory capability. At different temperatures, the characteristic spectra of Isochrysis galbana, Platymonas helgolanidica and Skeletonema costatuma have high degrees of similarity to their own species samples, while the spectra similarities of Alexandrium tamarense, Prorocentrum dentatum, Pseudo-nitzschia pungens, Chaetoceros curvisetus, Ch. Debilis, Ch. Didymus and Synechococcus sp. are not as significant as the other three species. C. curvisetus, Ch. Debilis and Ch. Didymus, belonging to genus Chaetoceros, have identical spectra and cannot be discriminated at all. Regarding all six diatom species as one class, the average discriminant error rate is below 9%. It is worth mentioning that the diatom class can be distinguished from A. tamarense and P. dentatum, which belong to Dinophyta. PMID:16024277

Zhang, Qian-Qian; Lei, Shu-He; Wang, Xiu-Lin; Wang, Lei; Zhu, Chen-Jian

2005-07-18

351

Effects of Departures from Ionization Equilibrium on Cooling-Flow X-Ray Spectra  

Microsoft Academic Search

X-ray spectra of galaxy cluster cooling cores have traditionally been modeled under the assumption that the cooling plasma is in ionization equilibrium. Departures from ionization equilibrium could affect the expected line-emission spectra from these objects and consequently the physical quantities inferred from such spectra. We have determined the elemental ionization fractions for six astrophysically abundant elements for temperatures from 104

Amalia K. Hicks; Claude R. Canizares

2001-01-01

352

Infrared Emissivity of Lunar Surface Features. 2. Interpretation.  

National Technical Information Service (NTIS)

Thermal emission spectra of six different areas on the lunar surface are discussed in the light of laboratory studies of the spectral emissivity of rocks and minerals. It is shown that the emission maxima characteristics of lunar spectra are similar to em...

J. W. Salisbury R. K. Vincent L. M. Logan G. R. Hunt

1970-01-01

353

Interpreting Astronomical Spectra  

NASA Astrophysics Data System (ADS)

Interpreting Astronomical Spectra D. Emerson Institute for Astronomy, Department of Physics and Astronomy, The University of Edingurgh "Interpreting Astronomical Spectra" describes how physical conditions such as temperature, density and composition can be obtained from the spectra of a broad range of astronomical environments ranging from the cold interstellar medium to very hot coronal gas and from stellar atmospheres to quasars. In this book the author has succeeded in providing a coherent and integrated approach to the interpretation of astronomical spectroscopy, placing the emphasis on the physical understanding of spectrum formation rather than on instrumental considerations. MKS units and consistent symbols are employed throughout so that the fundamental ideas common to diverse environments are made clear and the importance of different temperature ranges and densities can be seen. Aimed at senior undergraduates and graduates studying physics, astronomy and astrophysics, this book will also appeal to the professional astronomer.

Emerson, D.

1996-06-01

354

Interpreting Astronomical Spectra  

NASA Astrophysics Data System (ADS)

Interpreting Astronomical Spectra D. Emerson Institute for Astronomy, Department of Physics and Astronomy, The University of Edingurgh "Interpreting Astronomical Spectra" describes how physical conditions such as temperature, density and composition can be obtained from the spectra of a broad range of astronomical environments ranging from the cold interstellar medium to very hot coronal gas and from stellar atmospheres to quasars. In this book the author has succeeded in providing a coherent and integrated approach to the interpretation of astronomical spectroscopy, placing the emphasis on the physical understanding of spectrum formation rather than on instrumental considerations. MKS units and consistent symbols are employed throughout so that the fundamental ideas common to diverse environments are made clear and the importance of different temperature ranges and densities can be seen. Aimed at senior undergraduates and graduates studying physics, astronomy and astrophysics, this book will also appeal to the professional astronomer.

Emerson, D.

1999-03-01

355

Spectra of Ternary Alloys  

Microsoft Academic Search

The vibrational frequency-dsitribution spectra of the random one-dimensional ternary alloy AcB1-cC are accurately predicted for the first time by a statistical theory of small clusters embedded in a coherent-potential-approximation effective medium. The theory can be applied practically to real three-dimensional alloys.

Charles W. Myles; John D. Dow

1979-01-01

356

Moderation of neutron spectra  

SciTech Connect

Most of the accelerators that produce the various microenergetic neutron sources required for low-energy neutron dosimetry studies have been shut down. One alternative to accelerator-produced sources is the use of fission neutron or ({alpha},n) sources with unique neutron spectra. The problem with this solution is that maintenance of these sources is impractical. To help overcome this impracticality, the authors propose the use of moderating materials to produce a variety of spectra using a minimum number of sources. In the study, they performed Monte Carlo transport calculations under the following conditions: transporting neutrons from bare {sup 252}Cf or {sup 241}Am-Be sources from the center of various-sized spheres; tallying neutron spectra at 50 cm from the source. Of the twelve different moderating materials they studied, they found pure copper to be an ideal moderator. In this paper, they present flux-weighted energies, neutron spectra, and dose information for both {sup 252}Cf and {sup 241}Am-Be sources in bare and six-moderator configurations.

Hsu, H.H.; Chen, J. [Los Alamos National Lab., NM (United States). Health Physics Measurements Group

1997-05-01

357

Thermal Emission of Suspended Carbon Nanotube  

NASA Astrophysics Data System (ADS)

We study the thermal emission spectra of individual suspended carbon nanotube induced by electrical heating. Semiconducting and metallic devices exhibit different spectra, based on their distinctive bandstructures. These spectra are compared with the ideal blackbody emission spectrum. In the response region of our detector, i.e. visible to near infrared, the thermal emission spectra of semiconducting devices agree well with Planck's law, while the spectra of metallic devices show an additional peak around 1.65 eV. For semiconducting devices, the temperature of the nanotube was fitted to Planck's law, and was compared with the temperature fitted from the G band downshift as well as the Stokes:anti-Stokes intensity ratio. For devices showing thermal non-equilibrium, the electron temperature agrees well with G+ downshift, but deviates from G- downshift. Finally, for metallic devices, partially polarized IR emission was observed, and possible mechanisms are discussed.

Liu, Zuwei; Bushmaker, Adam; Aykol, Mehmet; Cronin, Steve

2011-03-01

358

X-ray diode using a silicon field-emission photocathode  

NASA Astrophysics Data System (ADS)

We have produced arrays of 10,000 sharp p-type silicon points using an etch plus oxidation method. These points were used as electron emitters. No high vacuum caseation or high temperature cleaning was needed to observe the electron emission. These are seen to be photosensitive sources of electrons at 200 K and 300 K. They were also used to produce AlK(alpha ) x rays. This constitutes the first use of etched, point arrays for generating electrons for x-ray sources.

Karain, Wael I.; Knight, Larry V.; Reyes-Mena, Arturo; Allred, David D.

1993-01-01

359

RELATIVISTIC BROADENING OF IRON EMISSION LINES IN A SAMPLE OF ACTIVE GALACTIC NUCLEI  

SciTech Connect

We present a uniform X-ray spectral analysis of eight type-1 active galactic nuclei that have been previously observed with relativistically broadened iron emission lines. Utilizing data from the XMM-Newton European Photon Imaging Camera (EPIC-pn) we carefully model the spectral continuum, taking complex intrinsic absorption and emission into account. We then proceed to model the broad Fe K{alpha} feature in each source with two different accretion disk emission line codes, as well as a self-consistent, ionized accretion disk spectrum convolved with relativistic smearing from the inner disk. Comparing the results, we show that relativistic blurring of the disk emission is required to explain the spectrum in most sources, even when one models the full reflection spectrum from the photoionized disk.

Brenneman, Laura W. [NASA's GSFC, Mail Code 662, Greenbelt, MD 20771 (United States); Reynolds, Christopher S. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States)

2009-09-10

360

Multispectral processing without spectra  

NASA Astrophysics Data System (ADS)

It is often the case that multiplications of whole spectra, component by component, must be carried out, for example when light reflects from or is transmitted through materials. This leads to particularly taxing calculations, especially in spectrally based ray tracing or radiosity in graphics, making a full-spectrum method prohibitively expensive. Nevertheless, using full spectra is attractive because of the many important phenomena that can be modeled only by using all the physics at hand. We apply to the task of spectral multiplication a method previously used in modeling RGB-based light propagation. We show that we can often multiply spectra without carrying out spectral multiplication. In previous work J. Opt. Soc. Am. A 11 , 1553 (1994) we developed a method called spectral sharpening, which took camera RGBs to a special sharp basis that was designed to render illuminant change simple to model. Specifically, in the new basis, one can effectively model illuminant change by using a diagonal matrix rather than the 33 linear transform that results from a three-component finite-dimensional model G. Healey and D. Slater, J. Opt. Soc. Am. A 11 , 3003 (1994). We apply this idea of sharpening to the set of principal components vectors derived from a representative set of spectra that might reasonably be encountered in a given application. With respect to the sharp spectral basis, we show that spectral multiplications can be modeled as the multiplication of the basis coefficients. These new product coefficients applied to the sharp basis serve to accurately reconstruct the spectral product. Although the method is quite general, we show how to use spectral modeling by taking advantage of metameric surfaces, ones that match under one light but not another, for tasks such as volume rendering. The use of metamers allows a user to pick out or merge different volume structures in real time simply by changing the lighting. 2003 Optical Society of America

Drew, Mark S.; Finlayson, Graham D.

2003-07-01

361

Multispectral processing without spectra.  

PubMed

It is often the case that multiplications of whole spectra, component by component, must be carried out,for example when light reflects from or is transmitted through materials. This leads to particularly taxing calculations, especially in spectrally based ray tracing or radiosity in graphics, making a full-spectrum method prohibitively expensive. Nevertheless, using full spectra is attractive because of the many important phenomena that can be modeled only by using all the physics at hand. We apply to the task of spectral multiplication a method previously used in modeling RGB-based light propagation. We show that we can often multiply spectra without carrying out spectral multiplication. In previous work [J. Opt. Soc. Am. A 11, 1553 (1994)] we developed a method called spectral sharpening, which took camera RGBs to a special sharp basis that was designed to render illuminant change simple to model. Specifically, in the new basis, one can effectively model illuminant change by using a diagonal matrix rather than the 3 x 3 linear transform that results from a three-component finite-dimensional model [G. Healey and D. Slater, J. Opt. Soc. Am. A 11, 3003 (1994)]. We apply this idea of sharpening to the set of principal components vectors derived from a representative set of spectra that might reasonably be encountered in a given application. With respect to the sharp spectral basis, we show that spectral multiplications can be modeled as the multiplication of the basis coefficients. These new product coefficients applied to the sharp basis serve to accurately reconstruct the spectral product. Although the method is quite general, we show how to use spectral modeling by taking advantage of metameric surfaces, ones that match under one light but not another, for tasks such as volume rendering. The use of metamers allows a user to pick out or merge different volume structures in real time simply by changing the lighting. PMID:12868625

Drew, Mark S; Finlayson, Graham D

2003-07-01

362

Martian neutron leakage spectra  

SciTech Connect

Energy spectra of Martian leakage neutrons are calculated by a high-energy nucleon-meson transport code using a Monte Carlo technique and a one-dimensional diffusion accelerated neutral-particle transport code, which solves the Boltzmann equation. Four series of calculations were made to simulate (1) a uniform surface layer containing various amounts of H/sub 2/O, (2) different burial depths of a 50% H/sub 2/O layer underneath a 1% H/sub 2/O layer, (3) changing atmospheric pressure, and (4) a thick CO/sub 2/ ice sheet overlying a ''dirty'' water ice sheet. We found that all calculated spectra at energies less than about 1000 eV could be fitted by a superposition of thermal and epithermal functions having four free parameters. Two of these parameters, the thermal and epithermal amplitudes, were found to vary systematically over ranges exceeding 1 order of magnitude and to specify uniquely the configuration in each of the series. We conclude that measurements of leakage neutron spectra should allow determination of the hydrogen content of surface layers buried to depths up to about 100 g/cm/sup 2/ and determination of the thickness of a polar dry ice cap up to thicknesses of about 250 g/cm/sup 2/. Variations of these parameters were also shown to depend on the composition of the assumed surface layers through the average atomic mass and the macroscopic scattering and absorption cross sections. copyright American Geophysical Union 1988

Drake, D.M.; Feldman, W.C.; Jakosky, B.M.

1988-06-10

363

Martian neutron leakage spectra  

NASA Astrophysics Data System (ADS)

A high-energy nucleon-meson transport code is used to calculate energy spectra of Martian leakage neutrons. Four calculations are used to simulate a uniform surface layer containing various amounts of water, different burial depths of a 50 percent water layer underneath a 1 percent water layer, changing atmospheric pressure, and a thick carbon dioxide ice sheet overlying a "dirty" water ice sheet. Calculated spectra at energies less than about 1000 eV were fitted by a superposition of thermal and epithermal functions having four free parameters, two of which (thermal and epithermal amplitudes) were found to vary systematically and to specify uniquely the configuration in each of the series. Parameter variations depend on the composition of the assumed surface layers through the average atomic mass and the macroscopic scattering and absorption cross sections. It is concluded that measurements of leakage neutron spectra should allow determination of the hydrogen content of surface layers buried to depths up to about 100 g/sq. cm and determination of the thickness of a polar dry ice cap up to a thickness of about 250 g/sq. cm.

Drake, D. M.; Feldman, W. C.; Jakosky, B. M.

1988-06-01

364

Formation of Martian Crystalline Hematite: New Information From Comparisons of Laboratory and TES Infrared Spectra  

Microsoft Academic Search

The Thermal Emission Spectrometer (TES) instrument aboard Mars Global Surveyor discovered several isolated deposits of gray, crystalline hematite in Sinus Meridiani, Aram Chaos, and Valles Marineris. Comparison of the average Sinus Meridiani hematite spectrum measured by TES to laboratory emissivity spectra for a variety of naturally occurring hematites shows small but potentially important differences. In particular, the emissivity minimum at

T. D. Glotch; R. V. Morris; P. R. Christensen

2002-01-01

365

SPECTRAFACTORY.NET: A DATABASE OF MOLECULAR MODEL SPECTRA  

SciTech Connect

We present a homogeneous database of synthetic molecular absorption and emission spectra from the optical to mm wavelengths for a large range of temperatures and column densities relevant for various astrophysical purposes, but in particular for the analysis, identification, and first-order analysis of molecular bands in spectroscopic observations. All spectra are calculated in the LTE limit from several molecular line lists, and are presented at various spectral resolving powers corresponding to several specific instrument simulations. The database is available online at http://www.spectrafactory.net, where users can freely browse, search, display, and download the spectra. We describe how additional model spectra can be requested for (automatic) calculation and inclusion. The database already contains over half a million model spectra for 39 molecules (96 different isotopologues) over the wavelength range 350 nm-3 mm ({approx}3-30000 cm{sup -1})

Cami, J. [SETI Institute, 515 N. Whisman Road, Mountain View, CA 94043 (United States); Van Malderen, R. [Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 200B, 3001 Leuven (Belgium); Markwick, A. J. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester (United Kingdom)], E-mail: jcami@uwo.ca, E-mail: Andrew.Markwick@manchester.ac.uk

2010-04-01

366

Peculiarities of atomic lines in sonoluminescense spectra  

NASA Astrophysics Data System (ADS)

Alkali-metal lines in SL spectra are broadened, asymmetrically shifted toward the red spectral region, unshifted narrow parent peaks are observed. The shape is influenced a number of parameters. The effects have no explanation. We model a line shape, assuming that line broadening arises from a density and line asymmetry results from superposition of spectra generated at different densities of a perturbing medium. Simulation shows that broad-band emission occurs within the density range of 10-400 Amg for KCl, LiCl, NaCl aqueous solutions under Ar at the ultrasound frequency of 20 kHz. The lower limit of the range shifts to higher density in order of K

Kazachek, M. V.; Gordeychuk, T. V.

2012-12-01

367

Staggered ladder spectra.  

PubMed

We exactly solve a Fokker-Planck equation by determining its eigenvalues and eigenfunctions: we construct nonlinear second-order differential operators which act as raising and lowering operators, generating ladder spectra for the odd- and even-parity states. The ladders are staggered: the odd-even separation differs from even-odd. The Fokker-Planck equation corresponds, in the limit of weak damping, to a generalized Ornstein-Uhlenbeck process where the random force depends upon position as well as time. The process describes damped stochastic acceleration, and exhibits anomalous diffusion at short times and a stationary non-Maxwellian momentum distribution. PMID:16486675

Arvedson, E; Wilkinson, M; Mehlig, B; Nakamura, K

2006-01-25

368

Spectra From Space : Main Menu  

NSDL National Science Digital Library

On-line science lesson (grades 7 - 9) - students learn about satellite spectra research, electromagnetic spectrum, do hands-on activities. In this lesson students investigate satellite missions operating in four electromagnetic bands. Students learn about spectra and why satellites gather certain kinds of spectra from space by using the Internet and doing hands-on activities. From the University of California, Berkeley.

1997-01-01

369

DISPLACEMENT SPECTRA FOR SEISMIC DESIGN  

Microsoft Academic Search

Displacement-based seismic design and assessment of structures require the reliable definition of displacement spectra for a wide range of periods and damping levels. The displacement spectra derived from acceleration spectra in existing seismic codes do not provide a suitable answer and there are no existing frequency-dependent attenuation relationships derived specifically for this purpose. Using a carefully processed dataset of European

JULIAN J. BOMMER; AMR S. ELNASHAI

1999-01-01

370

Average Lyman absorption from simulated QSO spectra  

NASA Astrophysics Data System (ADS)

Averagae flux decrements are computed below Ly-alpha and above Ly-beta, D(A) and between Ly-beta and the Lyman limit, D(B) of QSOs from synthetic spectra as a function of emission redshift on the basis of the presently known statistics of absorption lines. These simulations indicate that a steepening of the intrinsic spectrum of the QSO up to the Lyman limit is not required in order to explain the observed run of D(B)/D(A) with redshift, and that the average observed absorption is consistent with absorption line statistics.

Giallongo, E.; Gratton, R.; Trevese, D.

1990-06-01

371

Airborne Observations of the Infrared Emission Bands.  

National Technical Information Service (NTIS)

The data concerning low resolution airborne spectra from 5 to 8 microns available for a sample of 40 sources selected from the Infrared Astronomy Satellite low resolution spectral Atlas with polycyclic aromatic hydrocarbon (PAH) emission features, are dis...

M. Cohen J. Bregman F. C. Witteborn L. J. Allamandola D. H. Wooden

1989-01-01

372

Atlas of Far UV and Optical Spectra of Be Stars.  

National Technical Information Service (NTIS)

An atlas based on IUE (International Ultraviolet Explorer) high resolution spectra of the Be stars and their Balmer emission line profiles published by ESA in 1990 is described. It is intended to serve as a tool for future research and planning of both gr...

V. Doazan G. Sedmak M. Barylak L. Rusconi

1990-01-01

373

Thermal infrared emission spectroscopy of anhydrous carbonates  

Microsoft Academic Search

The objective of this study is to present the thermal emission spectra of various anhydrous, calcite- and dolomite-series carbonate minerals to illustrate the effect of the structural cation (Ca2+, Mg2+, Fe2+, Mn2+, Zn2+) on shifting the positions of the carbonate absorption bands. All of the carbonate mineral emission spectra included in this study exhibit three absorption features related to three

Phillip R. Christensen

1997-01-01

374

Computation of Spiral Spectra  

NASA Astrophysics Data System (ADS)

A computational linear stability analysis of spiral waves in a reaction-diffusion equation is performed on large disks. As the disk radius R increases, eigenvalue spectra converge to the absolute spectrum predicted by Sandstede and Scheel. The convergence rate is consistent with 1/R, except possibly near the edge of the spectrum. Eigenfunctions computed on large disks are compared with predicted exponential forms. Away from the edge of the absolute spectrum the agreement is excellent, while near the edge computed eigenfunctions deviate from predictions, probably due to finite-size effects. In addition to eigenvalues associated with the absolute spectrum, computations reveal point eigenvalues. The point eigenvalues and associated eigenfunctions responsible for both core and far-field breakup of spiral waves are shown.

Wheeler, Paul; Barkley, Dwight

2006-01-01

375

Ten Micron Spectra of Nova Cygni 1992  

NASA Astrophysics Data System (ADS)

We present infrared spectra of Nova Cygni 1992 taken with SpectroCam-10, the Cornell-built 10 microns spectrograph/camera for the Hale 200-inch telescope, in April and August 1992. A low-resolution 8--13 microns spectrum on April 13.5 shows a strong [Ne {\\small II}] 12.8 microns emission line and several hydrogen recombination lines on top of the free-free continuum. High resolution (R = 2000) spectra of the [Ne {\\small II}] and Humphreys alpha 12.37 microns lines on the same date show them to be ~ 2000 km s(-1) FWHM. The [Ne {\\small II}] line has a double-peaked central core and broad wings. On August 9, all lines as well as the continuum were approximately 10% as bright as in April. The wings of the [Ne {\\small II}] lines had essentially disappeared, leaving the central core. From the relative intensity of the [Ne {\\small II}] line and the free continuum in April, we calculate that the abundance of neon relative to hydrogen is at least four times greater than the solar composition. There is no sign of emission from dust on either date.

Hayward, T. L.; Miles, J. W.; Houck, J. R.; Gehrz, R. D.

1992-12-01

376

Modelling Spectra and Lightcurves from Supernovae  

NASA Astrophysics Data System (ADS)

Explosive transient astronomy is entering an era where supernovae (SNe) and gamma-ray bursts will be observed in real time with surveys like the LSST and Pan-STARRS, probing the universe back to very early times. The discovery of Pop III SNe could reveal many details about the formation and evolution of the first stars. Observations of shock breakout in SNe will provide new information about the engines powering these explosions. Shock breakout occurs when the shock wave from core collapse reaches an optically thin region and radiation can stream out. This first burst of radiation interacts with the star's immediate surroundings, showing the effects of the surrounding environment on emission and evolution. This profusion of data will contain brief snapshots from a wide range of progenitor systems which simulations can help interpret and explain. We present a new pipeline for creating model supernova spectra and lightcurves using radiation-hydrodynamic simulations and a new Spectrum code. Spectrum maps 1-D or 2-D data onto a two dimensional grid and assumes rotational symmetry, using monochromatic opacities to calculate emission and absorption as a function of radius and angle. We use these spectra to create lightcurves in any band from infrared to x-ray. This pipeline is being used to study the effects of stellar environment on core-collapse and Type Ia SNe, as well as several types of Pop III SNe.

Frey, Lucille; Even, W.; Whalen, D.; Fryer, C.; Hungerford, A.; Fontes, C.

2012-01-01

377

FLUORESCENCE CHARACTERIZATION OF IHSS HUMIC SUBSTANCES: TOTAL LUMINESCENCE SPECTRA WITH ABSORBANCE CORRECTION. (R822251)  

EPA Science Inventory

Total luminescence spectroscopy was applied to the fluorescence characterization of humic substances obtained from the International Humic Substances Society (IHSS). Results show that total luminescence spectra, represented as excitation-emission matrices (EEMs), may be used to d...

378

IUE-newsips spectra of sigma Geminorum  

NASA Astrophysics Data System (ADS)

The IUE spectra of sigma Gem have been taken from the NASA IUE archive using IDL (Interactive Data Language). The spectra have been observed in 1979-1986 period. All the spectra analysed in the present study have NEWSIPS reductions and consist of 25 LWP, 8 LWR and 5 SWP images in high resolution, and 2 LWP and 14 SWP images in low dispersion. The emission lines, identified as activity indicators and originating in the chromosphere and transition region, are seen in the spectra. The emission line fluxes and equivalent widths are computed based on Gaussian profile fitting procedures to examine the existence of any line flux variation that depends on time or orbital phase. It was found that there is a flux variation with time and orbital phase that is in good agreement with the photometric light curve variation. By comparing the flux variation with simultaneous light curve variation, it can be shown that there is a relation between the ultraviolet flux variation and the spot activity of the system, as shown by Ayres et al. (1984) and Engvold et al. (1988) based on their IUE (with IUESIPS reduction) spectral analysis. Moreover, it was inferred that there is no ultraviolet excess in sigma Gem by comparing the spectra of beta Gem taken as a comparison star. The Mg II h and k radial velocity curves of sigma Gem were in a good agreement with data obtained by Eker (1986) and Duemmler et al. (1997). The sinusoidal Mg II radial velocity curve solutions of the system give e = 0, P_orb. = 19.607+/-0.008 days, K = 34.86+/- 2.33 km s-1, gamma = 49.42+/- 1.87 km s-1 and T_o = 2445972.53+/- 0.28. Since the ultraviolet flux data are not conveniently distributed and are insufficient to determine the activity cycle, the evaluation of the ultraviolet flux activity cycle was not successful. Tables 3 to 11 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/391/641. Figures 1 to 10 are only available in electronic form at http://www.edpsciences.org

Ekmeki, F.; Karaku?, O.

2002-08-01

379

INFRARED SPECTRA OF ISOLATED PROTONATED POLYCYCLIC AROMATIC HYDROCARBON MOLECULES  

SciTech Connect

Gas-phase infrared (IR) spectra of larger protonated polycyclic aromatic hydrocarbon molecules, H{sup +}PAH, have been recorded for the first time. The ions are generated by electrospray ionization and spectroscopically assayed by IR multiple-photon dissociation (IRMPD) spectroscopy in a Fourier transform ion cyclotron resonance mass spectrometer using a free electron laser. IRMPD spectra of protonated anthracene, tetracene, pentacene, and coronene are presented and compared to calculated IR spectra. Comparison of the laboratory IR spectra to an astronomical spectrum of the unidentified IR emission (UIR) bands obtained in a highly ionized region of the interstellar medium provides for the first time compelling spectroscopic support for the recent hypothesis that H{sup +}PAHs contribute as carriers of the UIR bands.

Knorke, Harald; Langer, Judith; Dopfer, Otto [Institut fuer Optik und Atomare Physik, Technische Universitaet Berlin, Hardenbergstrasse 36, D-10623 Berlin (Germany); Oomens, Jos, E-mail: dopfer@physik.tu-berlin.d [FOM Institute for Plasma Physics, Rijnhuizen, P.O. Box 1207, 3430BE Nieuwegein (Netherlands)

2009-11-20

380

Nuclear temperatures from evaporation fragment spectra and observed anomalies  

NASA Astrophysics Data System (ADS)

The extreme back-angle evaporation spectra of alpha, lithium, beryllium, boron and carbon from different compound nuclei near A ? 100 (EX = 76210 MeV) have been compared with the predictions of standard statistical model codes such as cascade and gemini. It was found that the shapes of the alpha spectra agree well with the predictions of the statistical models. However, the spectra of lithium, beryllium, boron, and carbon show significantly gentler slopes implying higher temperature of the residual nuclei, even though the spectra satisfy all other empirical criteria of statistical emissions. The observed slope anomaly was found to be largest for lithium and decreases at higher excitation energy. These results could not be understood by adjusting the parameters of the statistical models or from reaction dynamics and might require examining the statistical model from a quantum mechanical perspective.

Ray, A.; De, A.; Chatterjee, A.; Kailas, S.; Banerjee, S. R.; Banerjee, K.; Saha, S.

2013-06-01

381

Decomposition of protein tryptophan fluorescence spectra into log-normal components. I. Decomposition algorithms.  

PubMed Central

Two algorithms of decomposition of composite protein tryptophan fluorescence spectra were developed based on the possibility that the shape of elementary spectral component could be accurately described by a uniparametric log-normal function. The need for several mathematically different algorithms is dictated by the fact that decomposition of spectra into widely overlapping smooth components is a typical incorrect problem. Only the coincidence of components obtained with various algorithms can guarantee correctness and reliability of results. In this paper we propose the following algorithms of decomposition: (1) the SImple fitting procedure using the root-Mean-Square criterion (SIMS) operating with either individual emission spectra or sets of spectra measured with various quencher concentrations; and (2) the pseudo-graphic analytical procedure using a PHase plane in coordinates of normalized emission intensities at various wavelengths (wavenumbers) and REsolving sets of spectra measured with various Quencher concentrations (PHREQ). The actual experimental noise precludes decomposition of protein spectra into more than three components.

Burstein, E A; Abornev, S M; Reshetnyak, Y K

2001-01-01

382

EFFECTS OF FORSTERITE GRAIN SHAPE ON INFRARED SPECTRA  

SciTech Connect

The Infrared Space Observatory (ISO) detected several sharp infrared features around young stars, comets, and evolved stars. These sharp features were identified as Mg-rich crystalline silicates of forsterite and enstatite by comparison with spectra from laboratory data. However, certain infrared emission bands in the observed spectra cannot be identified because they appear at slightly shorter wavelengths than the peaks in forsterite laboratory spectra, where the shapes of forsterite particles are irregular. To solve this problem, we measured infrared spectra of forsterite grains of various shapes (irregular, plate-like with no sharp edges, elliptical, cauliflower, and spherical) in the infrared spectral region between 5 and 100 mum. The spectra depend on particle shape. The spectra of the 11, 19, 23, and 33 mum bands, in particular, are extremely sensitive to particle shape, whereas some peaks such as the 11.9, 49, and 69 mum bands remained almost unchanged despite different particle shapes. This becomes most evident from the spectra of near-spherical particles produced by annealing an originally amorphous silicate sample at temperature from 600 to 1150 deg. C. The spectra of these samples differ strongly from those of other ones, showing peaks at much shorter wavelengths. At a higher annealing temperature of 1200 deg. C, the particle shapes changed drastically from spherical to irregular and the spectra became similar to those of forsterite particles with irregular shapes. Based on ISO data and other observational data, the spectra of outflow sources and disk sources may correspond to differences in forsterite shape, and further some unidentified peaks, such as those at 32.8 or 32.5 mum, may be due to spherical or spherical-like forsterite.

Koike, C.; Imai, Y.; Chihara, H.; Murata, K.; Tsuchiyama, A. [Department of Earth and Space Science, Osaka University, Toyonaka 560-0043 (Japan); Suto, H. [Subaru Telescope, National Astronomical Observatory of Japan, Hilo, HI (United States); Tachibana, S. [Department of Earth and Planetary Science, University of Tokyo, Tokyo 113-0033 (Japan); Ohara, S., E-mail: koike@astroboy.ess.sci.osaka-u.ac.j [Joining and Welding Research Institute, Osaka University, Ibaraki 567-0047 (Japan)

2010-02-01

383

NEUTRON ENERGY SPECTRA FROM NUCLEI EXCITED BY $mu$⁻MESON CAPTURE (thesis)  

Microsoft Academic Search

The neutron energy spectra from nuclear capture of mu mesons in Al, Ca, ; Fe, Ag, I, Au, and Pb were measured. Nuclear temperatures were deduced from the ; spectra according to the Weisskopf evaporation theory. Results were compared to ; other experimental measurements and consistency with compound nuclear theory was ; discussed. The direct neutron emission spectrum was calculated

Hagge

1963-01-01

384

Luminescence spectra of laser-induced cavitation bubbles near rigid boundaries  

Microsoft Academic Search

The luminescence spectra of laser-induced cavitation bubbles near rigid boundaries are measured for various relative distances between the bubble and the boundaries. We find that the luminescence spectra of bubbles collapsing near a single boundary consist only of a blackbody continuum. Luminescence from bubbles collapsing between two parallel rigid boundaries contains OH- emission bands similar to those found in multibubble

Emil A. Brujan; Gary A. Williams

2005-01-01

385

IUE observations of the Jovian dayglow emission  

NASA Astrophysics Data System (ADS)

IUE spectra of Jupiter are examined in light of recent models put forward to explain the anomalously bright ultraviolet emissions seen from the upper atmospheres of the outer planets. Chi-squared fits of the IUE spectra with model spectra produced by two proposed excitation mechanisms, electron impact and fluorescence of solar radiation, result in consistently higher chi-squared values for the solar fluorescence model. No conclusive evidence is found in the IUE data for the dominance of solar fluorescence over electron excitation in producing the Jovian dayglow emission.

McGrath, M. A.; Feldman, P. D.; Ballester, G. E.; Moos, H. W.

1989-06-01

386

Observational and theoretical spectra of supernovae  

NASA Astrophysics Data System (ADS)

Progress in nuclear astrophysics by means of quantitative supernova spectroscopy is discussed with special concentration on type Ia, Ib and Ic and on SN 1987A. Spectral calculations continue to support an exploding C/O white dwarf as the best model of a SN Ia. Deflagration model W7 produces good maximum light spectra of SN Ia and seems to have a better composition distribution compared to delayed detonation models, but proper treatment of opacity remains a problem and the physical basis of SN Ia explosions is still not completely understood. All models for SN Ia predict large quantities of 56Co in the ejecta, but it is not clear that observations confirm this. Although the evolutionary origin of SN Ia remains uncertain, there is recent evidence that transfer of hydrogen in a binary system may be involved, as long suspected. There has been progress in comparing dynamical models with the optical/IR spectra of SN 1987A. The evolution of the [OI] ??6300, 6364 feature and the presence of strong persistent HeI ?10 830 indicate that both the envelope and core material contribute substantially to the formation of emission lines in the nebular phase and that neither the core nor the envelope can be neglected. Blending with nearby hydrogen lines may affect both of these spectral features, thereby complicating the analysis of the lines. The effects of continuum transfer and photoionization have been included and are under study. The discrepancies between theoretical and observed spectra are due primarily to the one-dimensional hydrodynamic models. The spectral data are not consistent with the high density ``spike'' (in radial coordinate) of the core material that is predicted by all such models. Analysis of the light curves of SN Ib and SN Ic supernovae implies that there are significant differences in their physical properties. Some SN Ib have considerably more ejecta mass than SN Ic events. SN Ib require He-rich atmospheres to produce the observed strong optical lines of HeI somewhat after maximum. SN Ic events require a considerable depletion, if not absence, of helium. Calculations of the nebular phase after about 200 days show that the optical spectra of SN Ib/c will not reveal HeI even if helium is present. The spectra at that phase are rather insensitive to variations in the mass and composition. The similarity of the optical spectra of SN Ib and Ic events at late times thus does not mean that they are physically very similar. Observations of the HeI ?10 830 line could provide a good diagnostic of the atmospheric composition of Sn Ib and SN Ic.

Wheeler, J. Craig; Swartz, Douglas A.; Harkness, Robert P.

1993-05-01

387

Effects of Microwave Desert Surface Emissivity on AMSU-A Data Assimilation  

Microsoft Academic Search

A microwave land emissivity library has been de- veloped from the Advanced Microwave Sounding Unit (AMSU) data for improving satellite data assimilation. Over the desert, surface emissivity is classified according to soil type into several spectra. For sand, loamy sand, and sandy loam, which contain some large mineral particles, the emissivity spectra generally decrease with frequency. For other desert types

Banghua Yan; Fuzhong Weng

2011-01-01

388

The Ultraviolet Emission Spectra of AN HII Region  

NASA Astrophysics Data System (ADS)

ONE OF THE ADVANTAGES OF THE NEW INSTRUMENTS SUCH AS THE HUBBLE SPACE TELESCOPE IS TO BE ABLE TO STUDY THE UNIVERSE AT WAVELENGTHS PREVIOUSLY UNOBSERVABLE FROM UNDER THE EARTH'S ATMOSPHERE. ONE THE THESE IS THE UV REGION OF THE STECTRUM. USING HST'S FOS, I WOULD LIKE TO TAKE A UV SPETRUM OF AN HII REGION, M8, THE LAGOON NEBULA (HOURGLASS REGION). HII REGIONS ARE AREAS OF STARBIRTH AND ARE SAMPLES OF THE INTERSTELLAR MATTER OUT OF WHICH STARS ARE BEING BORN. HOT, YOUNG O STARS WHICH RADIATE STRONGLY IN THE UV ARE EMBEDDED IN M8. MANY EMSSION LINES ARE EXPECTED BETWEEN 912-3300 ANGTROMS. USING WF/PC, AN IMAGE OF THE HOURGALSS WILL BE TAKEN LOOKING FOR FILIMENTARY STRUCTURE AND NEW BORN STARS.

Cox, Nancy

1992-07-01

389

Dynamic spectra of Saturn kilometric radiation  

NASA Astrophysics Data System (ADS)

Dynamic spectra of Saturn kilometric radiation (SKR) obtained by the Voyager planetary radio astronomy experiment have been searched for variations at a time scale longer than that of the arcs (about 1 hour). Two kinds of episodic changes of the shape of the dynamic spectrum can be distinguished: one is an overall long-term change, lasting for one or several Saturn rotations; the other is a modification of the dynamic spectrum from one rotation to another, limited to the sub-solar longitude range from about 270 deg through 0 deg to about 60 deg. Both correspond to a change in the shape of the intensity spectrum of the emission. The long-term variation probably contains the so-called 'Dione gaps', together with similar and sometimes much longer events. The already discovered influence of strong solar wind activity corresponds to increases of the average intensity level of the emission, but not to changes in the shape of its intensity spectrum. Both kinds of episodic spectral variations are usually observed in magnetically quiet conditions, in particular when Saturn enters Jupiter's magnetic tail. These changes of the SKR spectrum are compared with those already observed in the terrestrial kilometric radiation. They could be due to complex propagation effects, temporary modifications of the emission beam or changes in the source altitude.

Genova, F.; Pedersen, B. M.; Lecacheux, A.

1983-11-01

390

Time spectra of patent information  

Microsoft Academic Search

Information spectra are defined as intervals between equivalent information events. Their relations to negative binomial and negative polynomial distributions and urn models are explained. Basic properties of empirical information spectra from patent literature are shown and discussed in connection withHaitun's views on Z type information distributions,Sichel's GIGP model andTrofimenko's study on formation and decay of author groups.

M. Kunz

1987-01-01

391

Wavelet Denoising of Infrared Spectra  

Microsoft Academic Search

The application of wavelet denoising to infrared spectra was investigated. Six different wavelet denoising methods (SURE, VISU, HYBRID, MINMAX, MAD and WAVELET PACKETS) were applied to pure infrared spectra with various added levels of homo- and heteroscedastic noise. The performances of the wavelet denoising methods were compared with the standard Fourier and moving mean filtering in terms of root mean

Bjrn K. Alsberg; Andrew M. Woodward; Michael K. Winson; Jem Rowland; Douglas B. Kell

1997-01-01

392

PAHFIT: Properties of PAH Emission  

NASA Astrophysics Data System (ADS)

PAHFIT is an IDL tool for decomposing Spitzer IRS spectra of PAH emission sources, with a special emphasis on the careful recovery of ambiguous silicate absorption, and weak, blended dust emission features. PAHFIT is primarily designed for use with full 5-35 micron Spitzer low-resolution IRS spectra. PAHFIT is a flexible tool for fitting spectra, and you can add or disable features, compute combined flux bands, change fitting limits, etc., without changing the code. PAHFIT uses a simple, physically-motivated model, consisting of starlight, thermal dust continuum in a small number of fixed temperature bins, resolved dust features and feature blends, prominent emission lines (which themselves can be blended with dust features), as well as simple fully-mixed or screen dust extinction, dominated by the silicate absorption bands at 9.7 and 18 microns. Most model components are held fixed or are tightly constrained. PAHFIT uses Drude profiles to recover the full strength of dust emission features and blends, including the significant power in the wings of the broad emission profiles. This means the resulting feature strengths are larger (by factors of 2-4) than are recovered by methods which estimate the underlying continuum using line segments or spline curves fit through fiducial wavelength anchors.

Smith, J. D.; Draine, Bruce

2012-10-01

393

Three-dimensional fluorescence spectra of human blood  

NASA Astrophysics Data System (ADS)

The absorption spectroscopy and three-dimensional fluorescence spectra of human blood were measured and an attempt was made to exploit the endogenous fluorophores of major peaks in the UV and visible light. Fluorescence excitation wavelength range 260-540 nm were used to induce the fluorescence spectra of human blood, and the corresponding emission spectra were acquired from a range starting 20 nm above the excitation wavelength and extending to 780 nm. Fluorescence excitation-emission matrix was used to exploit endogenous fluorophores. The results indicate that the absorption peaks for human blood appear at 274, 345, 415, 541 and 576 nm, and the remarkable emission peaks occur at excitation-emission wavelength pairs of 260-630, 280-340, 340-460, 450-520 nm. According to the previous referenced studies, these fluorescence peaks were attributed to endogenous porphyrins, tryptophan, NAD(P)H, and FAD, respectively. The results obtained can be used to evaluate the distorting effect of blood on the autofluorescence signals of human tissues for optical biopsy.

Li, Buhong; Zhang, Zhenxi; Xie, Shusen; Chen, Rong

2006-01-01

394

Development of A New Background Reduction Method for WXM/HETE-2 and Its Application for Bright GRB Spectra  

SciTech Connect

HETE-2 detected gamma-ray bursts (GRBs) since its launch on 9 October 2000. For spectral analyses using data of WXM on-board HETE-2, background spectra are conventionally obtained with time regions before and/or after prompt emission. In some cases, the background spectra change during the prompt emission and/or the downlink trouble causes a loss of data around the prompt emission. If this is the case, the problem seems to lie in the fact that the conventional method cannot obtain correct background spectra. To make more appropriate background spectra, we develop a new analysis method using mask patterns of the WXM. The background spectra are estimated with shaded regions by the WXM mask pattern using the prompt emission data. Our new method might obtain a reliable result for a spectrum of GRB 030329. In this paper, we introduce our new analysis method and show a preliminary spectral result.

Takahashi, I.; Nakagawa, Y. E.; Yoshida, A.; Sugita, S. [Department of Physics and Mathematics, Aoyama Gakuin University, 5-10-1 Fuchinobe, Sagamihara, Kanagawa 229-8558 (Japan); Tamagawa, T.; Kuwahara, M. [Institute of Physical and Chemical Research, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Kawai, N.; Arimoto, M.; Shimokawabe, T.; Ishimura, T.; Vasquez, N. [Department of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551 (Japan); Suzuki, M.; Sato, R. [ISAS/JAXA, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510 (Japan); Shirasaki, Y. [National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan); Ricker, George R. [Center for Space Research, MIT, 77 Vassar Street, Cambridge, MA 02139-4307 (United States)

2008-05-22

395

Fluorescence spectra of bioaerosols exposed to ozone in a laboratory reaction chamber to simulate atmospheric processing  

NASA Astrophysics Data System (ADS)

Laboratory measurements demonstrating the effects of ozone on aerosolized B. thuringiensis, as revealed by fluorescence spectra, are reported. The fluorescence emission peak around 330 nm (excited at 263nm) decreases somewhat in intensity and becomes slightly blue-shifted. Further, the fluorescence emission around 400 nm-550 nm is less affected by the ozone than is the 330 nm (tryptophan) peak.

Pan, Yong-Le; Hill, Steven C.; Pinnick, Ronald G.; Santarpia, Joshua L.; Baker, Neal; Alvarez, Benjamin; Ratnesar-Shumate, Shanna; Cottrell, Brian; McKee, Laura

2011-05-01

396

On the Spectral Variance of MGS TES Spectra in the 300-500 cm-1 Range  

Microsoft Academic Search

The Thermal Emission Spectrometer (TES) aboard NASA mission Mars Global Surveyor (MGS) is collecting 200 - 1600 cm-1 thermal emission spectra since September 1997. The principal purpose of TES is to determine and map the Mars surface composition. Spectral features directly ascribable to surface minerals have been identified in the 300 - 500 cm-1 spectral range. Outcrops of hematite have

F. Altieri; G. Bellucci

2001-01-01

397

SPECTRA-IV, benchmark spectra based on LIB-IV  

Microsoft Academic Search

Flux and adjoint spectra for each of the Cross Section Evaluation Working Group fast reactor benchmarks are numerically and graphically presented in this handbook. The spectra were computed using a 50-group cross-section library (LIB-IV) that was generated with the MINX processing code using ENDF\\/B-IV data. The graphical figures compare smooth interpolated curves for the central flux, edge flux, central adjoint,

Kidman

1979-01-01

398

Anisotropic spectra of acoustic turbulence  

SciTech Connect

We found universal anizopropic spectra of acoustic turbulence with the linear dispersion law {omega}(k)=ck within the framework of generalized kinetic equation which takes into account the finite time of three-wave interactions. This anisotropic spectra can assume both scale-invariant and non-scale-invariant form. The implications for the evolution of the acoustic turbulence with nonisotropic pumping are discussed. The main result of the article is that the spectra of acoustic turbulence tend to become more isotropic. (c) 2000 The American Physical Society.

L'vov, V. S. [Departments of Chemical Physics, The Weizmann Institute of Science, Rehovot 76100, (Israel); Institute for Automatization, Russian Academy of Science, Novosibirsk 630090, Russia (Russian Federation); L'vov, Yu. V. [Department of Mathematical Sciences, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Pomyalov, A. [Departments of Chemical Physics, The Weizmann Institute of Science, Rehovot 76100, (Israel)

2000-03-01

399

Unveiling the complexity of the X-ray spectra of Seyfert 1 galaxies  

NASA Astrophysics Data System (ADS)

The present thesis deals with the study of the material close to the active nuclei of Seyfert 1 galaxies that are absorbing and emitting radiation in the X-ray spectral range. We perform a comprehensive detailed analysis of all the UV and X-ray data taken by the XMM-Newton satellite of a small sample of five Seyfert 1 galaxies: UGC 11763, ESO G359-G19, HE 1143-1810, CTS A08.12, and Mkn 110. Our aim is to characterize the different components of the gas that print the absorption and emission features in the X-ray spectra of these objects. The continuum emission is studied through the EPIC spectra taking advantage of the spectral range of these cameras. The high resolution RGS spectra are analyzed in order to search for and characterize, if found, the absorbing features and the emission line features that arise in the spectra of these sources.

Cardaci, Mnica V.

2010-09-01

400

Cluster analysis on mass spectra of biogenic secondary organic aerosol  

NASA Astrophysics Data System (ADS)

Biogenic secondary organic aerosols (BSOA) are of high importance in the atmosphere. The formation of SOA from the volatile organic compound (VOC) emissions of selected trees was investigated in the JPAC (Jlich Plant Aerosol Chamber) facility. The VOC (mainly monoterpenes) were transferred into a reaction chamber where vapors were photo-chemically oxidized and formed BSOA. The aerosol was characterized by aerosol mass spectrometry (Aerodyne Quadrupol-AMS). Inside the AMS, flash-vaporization of the aerosol particles and electron impact ionization of the evaporated molecules cause a high fragmentation of the organic compounds. Here, we present a classification of the aerosol mass spectra via cluster analysis. Average mass spectra are produced by combination of related single mass spectra to so-called clusters. The mass spectra were similar due to the similarity of the precursor substances. However, we can show that there are differences in the BSOA mass spectra of different tree species. Furthermore we can distinguish the influence of the precursor chemistry and chemical aging. BSOA formed from plants exposed to stress can be distinguished from BSOA formed under non stressed conditions. Significance and limitations of the clustering method for very similar mass spectra will be demonstrated and discussed.

Spindler, C.; Kiendler-Scharr, A.; Kleist, E.; Mensah, A.; Mentel, T.; Tillmann, R.; Wildt, J.

2009-04-01

401

Spectra of simulated lightning on Venus, Jupiter, and Titan.  

PubMed

Laser-induced plasmas in various gas mixtures were used to simulate lightning in other planetary atmospheres. This method of simulation has the advantage of producing short-duration, high-temperature plasmas free from electrode contamination. The laser-induced plasma discharges in air are shown to accurately simulate terrestrial lightning and can be expected to simulate lightning spectra in other planetary atmospheres. Spectra from 240 to 880 nm are presented for simulated lightning in the atmospheres of Venus, Earth, Jupiter, and Titan. The spectra of lightning on the other giant planets are expected to be similar to that of Jupiter because the atmospheres of these planets are composed mainly of hydrogen and helium. The spectra of Venus and Titan show substantial amounts of radiation due to the presence of carbon atoms and ions and show CN Violet radiation. Although small amounts of CH4 and NH3 are present in the Jovian atmosphere, only emission from hydrogen and helium is observed. Most differences in the spectra can be understood in terms of the elemental ratios of the gas mixtures. Consequently, observations of the spectra of lightning on other planets should provide in situ estimates of the atmospheric and aerosol composition in the cloud layers in which lightning is occurring. In particular, the detection of inert gases such as helium should be possible and the relative abundance of these gases compared to major constituents might be determined. PMID:11539656

Borucki, W J; McKenzie, R L; McKay, C P; Duong, N D; Boac, D S

1985-01-01

402

The IRAS low-resolution spectra of planetary nebulae  

SciTech Connect

This paper presents the low-resolution spectra of 170 planetary nebulae observed by IRAS, most of which were not included in the Atlas of Low-Resolution Spectra. These have been classified into eight groups based upon the spectral morphology, with emphasis on the dust continuum rather than the spectral lines. The Low-Resolution Spectrometer (LRS) spectra are nearly evenly divided between spectra which show only a dust continuum with no lines, and spectra where there are strong lines with a dust continuum appearing longwards of about 15 microns. A study has been made of the strength of the 11.3-micron PAH emission feature as a function of the nebular C/O ratio, combining ground-based and LRS data. The C/O ratio for IC 2621 is derived from IUE spectra and used in this study. The 11.3-micron feature is present with essentially constant strength in all nebulae with C/O above about 1. Only marginal evidence exists for its presence below C/O about 1 and then at a level about 5 times lower than in carbon-rich nebulae. 48 refs.

Volk, K.; Cohen, M. (SETI Institute, Mountain View, CA (USA) California Univ., Berkeley (USA))

1990-08-01

403

Spectra of simulated lightning on Venus, Jupiter, and Titan  

NASA Astrophysics Data System (ADS)

Laser-induced plasmas in various gas mixtures were used to simulate lightning in other planetary atmospheres. This method of simulation has the advantage of producing short-duration, high-temperature plasmas free from electrode contamination. The laser-induced plasma discharges in air are shown to accurately simulate terrestrial lightning and can be expected to simulate lightning spectra in other planetary atmospheres. Spectra from 240 to 880 nm are presented for simulated lightning in the atmospheres of Venus, earth, Jupiter, and Titan. The spectra of lightning on the other giant planets are expected to be similar to that of Jupiter because the atmospheres of these planets are composed mainly of hydrogen and helium. The spectra of Venus and Titan show substantial amounts of radiation due to the presence of carbon atoms and ions and show CN Violet radiation. Although small amounts of CH4 and NH3 are present in the Jovian atmosphere, only emission from hydrogen and helium is observed. Most differences in the spectra can be understood in terms of the elemental ratios of the gas mixtures. Consequently, observations of the spectra of lightning on other planets should provide in situ estimates of the atmospheric and aerosol composition in the cloud layers in which lightning is occurring. In particular, the detection of inert gases such as helium should be possible and the relative abundance of these gases compared to major constituents might be determined.

Borucki, W. J.; McKenzie, R. L.; McKay, C. P.; Duong, N. D.; Boac, D. S.

1985-11-01

404

IONIZED REFLECTION SPECTRA FROM ACCRETION DISKS ILLUMINATED BY X-RAY PULSARS  

SciTech Connect

X-ray reflection signatures are observed around multiple classes of accreting compact objects. Modeling these features yields important constraints on the physics of accretion disks, motivating the development of X-ray reflection models appropriate for a variety of systems and illumination conditions. Here, constant density ionized X-ray reflection models are presented for a disk irradiated with a very hard power-law X-ray spectrum ({Gamma} < 1) and a variable high-energy cutoff. These models are then applied to the Suzaku data of the accreting X-ray pulsar LMC X-4, where very good fits are obtained with a highly ionized reflector responsible for both the broad Fe K{alpha} line and the soft excess. The ionized reflector shows strong evidence for significant Doppler broadening and is redshifted by {approx}10{sup 4} km s{sup -1}. These features indicate that the reflecting material is associated with the complex dynamics occurring at the inner region of the magnetically truncated accretion disk. Thus, reflection studies of X-ray pulsar spectra may give important insights into the accretion physics at the magnetospheric radius.

Ballantyne, D. R.; Purvis, J. D.; Strausbaugh, R. G. [Center for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Hickox, R. C., E-mail: david.ballantyne@physics.gatech.edu [Department of Physics and Astronomy, Dartmouth College, 6127 Wilder Laboratory, Hanover, NH 03755 (United States)

2012-03-10

405

Longslit Spectra of the Galaxy NGC 1569  

NASA Astrophysics Data System (ADS)

Longslit spectra of the starburst galaxy NGC 1569 are displayed. This ground-based data was acquired at the 90-inch telescope of the Steward Observatory (Kitt Peak, Arizona) in September 1998. Results for the red region of the spectrum are presented. The variation of ionization and gas density as a function of position in the galaxy are shown. The background stellar component of the galaxy is separated from the nebular emission spectrum. These ground-based results will be used with space-based data to be acquired by astronomers at South Carolina State University, the University of Maryland and Rice University as part of an approved Cycle 8 Hubble Space Telescope program.

Duenas, Ely

2000-11-01

406

Radioactive sample effects on EDXRF spectra  

SciTech Connect

Energy dispersive X-ray fluorescence (EDXRF) is a rapid, straightforward method to determine sample elemental composition. A spectrum can be collected in a few minutes or less, and elemental content can be determined easily if there is adequate energy resolution. Radioactive alpha emitters, however, emit X-rays during the alpha decay process that complicate spectral interpretation. This is particularly noticeable when using a portable instrument where the detector is located in close proximity to the instrument analysis window held against the sample. A portable EDXRF instrument was used to collect spectra from specimens containing plutonium-239 (a moderate alpha emitter) and americium-241 (a heavy alpha emitter). These specimens were then analyzed with a wavelength dispersive XRF (WDXRF) instrument to demonstrate the differences to which sample radiation-induced X-ray emission affects the detectors on these two types of XRF instruments.

Worley, Christopher G [Los Alamos National Laboratory

2008-01-01

407

Raman Spectroscopy Databases | Spectra Databases  

NSDL National Science Digital Library

This site is a clearinghouse of vibrational frequencies and Raman, mass, fluorescence, neutron scattering and infrared spectra. Both organic and mineral databases are included. The site features free access from both university and industry sources.

Spectroscopynow.com

408

Forecasting and Verifying Hydrometeor Spectra.  

National Technical Information Service (NTIS)

Forecasts and measurements of ice water content, hydrometeor size spectra and crystal habit are being provided for Air Force tests. Climatology, synoptic, rawinsonde and satellite data are used for forecasts in excess of three hours. Shorter range forecas...

A. A. Barnes V. G. Plank

1976-01-01

409

RW Aur spectra (Alencar+, 2005)  

NASA Astrophysics Data System (ADS)

The observations, obtained over a decade, were carried out at Lick Observatory. ************************************************************************** * * * A major hard disk failure on the author's workstation containing * * the FITS files of the spectra made the files actually unavailable * * * ************************************************************************** (1 data file).

Alencar, S. H. P.; Basri, G.; Hartmann, L.; Calvet, N.

2006-07-01

410

The 8-13 micron spectra of comets and the composition of silicate grains  

NASA Astrophysics Data System (ADS)

We have analyzed the existing spectra of seven comets which show an emission feature at 7.8-13 micrometers. Most have been converted to a common calibration, taking into account the SiO feature in late-type standard stars. The spectra are compared with spectra of the Trapezium, interplanetary dust particles (IDPs), laboratory mineral samples, and small particle emission models. The emission spectra show a variety of shapes; there is no unique 'cometary silicate'. A peak at 11.20-11.25 micrometers, indicative of small crystalline olivine particles, is seen in only three comets of this sample, P/Halley, Bradfield 1987 XXIX, and Levy 1990 XX. The widths of the emission features range from 2.6 to 4.1 micrometers (FWHM). To explain the differing widths and the broad 9.8 micrometers maximum, glassy silicate particles, including both pyroxene and olivine compositions, are the most plausible candidates. Calculations of emission models confirm that small grains of glassy silicate well mixed with carbonaceous material are plausible cometary constituents. No single class of chondritic aggregate IDPs exhibits spectra closely matching the comet spectra. A mixture of IDP spectra, particularly the glass-rich aggregates, approximately matches the spectra of comets P/Halley, Levy, and Bradfield 1987 XXIX. Yet, if comets are simply a mix of IDP types, it is puzzling that the classes of IDPs are so distinct. None of the comet spectra match the spectrum of the Trapezium. Thus, the mineralogy of the cometary silicates is not the same as that of the interstellar medium. The presence of a component of crystalline silicates in comets may be evidence of mixing between high- and low-temperature regions in the solar nebula.

Hanner, M. S.; Lynch, D. K.; Russell, R. W.

1994-04-01

411

Temporal Evolution of GRB Spectra: Leptonic and Hadronic  

NASA Astrophysics Data System (ADS)

As the Fermi observatory has revealed, the GRB light curves show variant behaviours in different energy bands. Especially, the onset of GeV emission tend to lag that at lower energy. Various models to explain the GeV-delay, including early afterglow models or hadronic models, have been proposed. We have developed a time-dependent code for emission processes with one-zone approximation. The temporal evolution of GRB spectra is discussed based on leptonic inverse Compton and hadronic cascade models. This offers important predictions for future observations such as CTA.

Asano, Katsuaki; Mszros, Peter

2012-09-01

412

Visible emission of hydrogen flames  

SciTech Connect

The common misconception that hydrogen flames are not visible is examined. Examples are presented of clearly visible emissions from typical hydrogen flames. It is shown that while visible emissions from these flames are considerably weaker than those from comparable hydrocarbon flames, they are indeed visible, albeit at reduced light levels in most cases. Detailed flame spectra are presented to characterize flame emission bands in the ultraviolet, visible and infrared regions of the spectrum that result in a visible hydrogen flame. The visible blue emission is emphasized, and recorded spectra indicate that fine spectral structure is superimposed on a broadband continuum extending from the ultraviolet into the visible region. Tests were performed to show that this emission does not arise from carbon or nitrogen chemistry resulting from carbon-containing impurities (hydrocarbons) in the hydrogen fuel or from CO{sub 2} or N{sub 2} entrainment from the surrounding air. The spectral structure, however, is also observed in methane flames. The magnitude of the broadband emission increases with flame temperature in a highly nonlinear manner while the finer spectral structure is insensitive to temperature. A comparison of diffusion and premixed H{sub 2} flames shows that the fine scale structure is comparable in both flames. (author)

Schefer, R.W.; Kulatilaka, W.D.; Patterson, B.D.; Settersten, T.B. [Combustion Research Facility, Sandia National Laboratories, Livermore, CA 94551-0969 (United States)

2009-06-15

413

Atomic and Molecular Aspects of Astronomical Spectra  

NASA Astrophysics Data System (ADS)

In the first section we present the atomic part where a C2+ atomic target was prepared and used to generate theoretical data to investigate recombination lines arising from electron-ion collisions in thin plasma. R-matrix method was used to describe the C2+ plus electron system. Theoretical data concerning bound and autoionizing states were generated in the intermediate-coupling approximation. The data were used to generate dielectronic recombination data for C+ which include transition lines, oscillator strengths, radiative transition probabilities, emissivities and dielectronic recombination coefficients. The data were cast in a line list containing 6187 optically-allowed transitions which include many C II lines observed in astronomical spectra. This line list was used to analyze the spectra from a number of astronomical objects, mainly planetary nebulae, and identify their electron temperature. The electron temperature investigation was also extended to include free electron energy analysis to investigate the long-standing problem of discrepancy between the results of recombination and forbidden lines analysis and its possible connection to the electron distribution. In the second section we present the results of our molecular investigation; the generation of a comprehensive, calculated line list of frequencies and transition probabilities for H2D+. The line list contains over 22 million rotational-vibrational transitions occurring between more than 33 thousand energy levels and covers frequencies up to 18500 cm-1. About 15% of these levels are fully assigned with approximate rotational and vibrational quantum numbers. A temperature-dependent partition function and cooling function are presented. Temperature-dependent synthetic spectra for the temperatures T=100, 500, 1000 and 2000 K in the frequency range 0-10000 cm-1 were also generated and presented graphically.

Sochi, Taha

2012-11-01

414

Mutational spectra of human cancer  

Microsoft Academic Search

The purpose of this review is to summarize the evidence that can be used to reconstruct the etiology of human cancers from\\u000a mutations found in tumors. Mutational spectra of the tumor suppressor gene p53 (TP53) are tumor specific. In several cases, these mutational spectra can be linked to exogenous carcinogens, most notably for\\u000a sunlight-associated skin cancers, tobacco-associated lung cancers, and

Gerd P. Pfeifer; Ahmad Besaratinia

2009-01-01

415

Thermal Emission Spectroscopy of Laboratory Regoliths  

NASA Astrophysics Data System (ADS)

The interpretation of emission spectra of planetary objects requires laboratory measurements for comparison. Emissivity measurements carried out at atmospheric pressure give not always a true analogue for the actual spectra of airless planetary objects, but they still provide valuable and practically indispensable results. The present study provides emissivity spectra of ten feldspars in the wavelength range from 6.3 to 17.5 ?m, in dependence on the samples' grain size. The grain size is varied in the range from < 25 to 180 ?m. Moreover, emissivity spectra are given for several binary mixtures of feldspar and pyroxene. It was found that linear mixing (i.e., linear combination of the component spectra, according to the components' volume percentages) provides a good approximation for the measured mixture spectrum. This was found not only for the wet-sieved coarser grain size fractions, where reflectance and emittance are dominated by surface scattering, but also for the grain size fractions < 63 ?m, whose spectra reveal a significant contribution of volume scattering, and where the mixing was therefore expected to be nonlinear.

Wagner, C.

2000-03-01

416

Demonstrating Absorption Spectra Using Commercially Available Incandescent Light Bulbs  

NASA Astrophysics Data System (ADS)

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

Birriel, Jennifer J.

417

Fluorescence spectra of blood and urine for cervical cancer detection  

NASA Astrophysics Data System (ADS)

In the current study, the fluorescence emission spectra (FES) and Stokes shift spectra (SSS) of blood and urine samples of cervical cancer patients were obtained and compared to those of normal controls. Both spectra showed that the relative intensity of biomolecules such as porphyrin, collagen, Nicotinamide adenine dinucleotide, and flavin were quite out of proportion in cervical cancer patients. The biochemical mechanism for the elevation of these fluorophores is not yet definitive; nevertheless, these biomolecules could serve as tumor markers for diagnosis, screening, and follow-up of cervical cancers. To the best of our knowledge, this is the first report on FES and SSS of blood and urine of cervical cancer patients to give a sensitivity of 80% and specificity of 78%.

Masilamani, Vadivel; AlSalhi, Mohamad Saleh; Vijmasi, Trinka; Govindarajan, Kanaganaj; Rathan Rai, Ram; Atif, Muhammad; Prasad, Saradh; Aldwayyan, Abdullah S.

2012-09-01

418

On the nature of gamma-ray burst spectra  

Microsoft Academic Search

The recent discovery of low-energy absorption features in the spectra of gamma-ray bursts (GRBs) reported by Murakami et al. (1988)