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Sample records for k-alpha emission spectra

  1. K alpha line emission during solar X-ray bursts

    NASA Technical Reports Server (NTRS)

    Phillips, K. J. H.; Neupert, W. M.

    1973-01-01

    Calculations of K alpha line emission from S, Ar, Ca and Fe are presented. It is reported that on the basis of data for hard X-ray bursts, the flux during most impulsive, non-thermal events is likely to be weak, though for a few strong bursts, a flux of approximately 100 photons/cm/s may be expected. The amount of S K alpha emission particularly is sensitively dependent on the value of the lower energy bound of the non-thermal electron distribution, offering a possible means of determining this. Thermal K alpha emission is only significant for Fe ions. The calculated thermal K alpha radiation is much less than that observed during an intense soft X-ray burst. It is concluded that a detailed temperature structure for the emission source is required in order to explain the discrepancy.

  2. K alpha line emission during solar X-ray bursts

    NASA Technical Reports Server (NTRS)

    Phillips, K. J. H.; Neupert, W. M.

    1973-01-01

    The expected flux of K alpha line emission from sulfur, argon, calcium, and iron is calculated during both thermal and nonthermal solar X-ray events. Such emission is shown to be weak during the course of most of the nonthermal hard X-ray bursts that Kane and Anderson (1970) have observed. If Compton backscattering is significant at high energies, the flux is reduced still further for disk flares, but it is noted that the strong, near-limb burst of June 26 would have produced about 100 photons /sq cm/sec of sulfur and iron K alpha emission. The impulsive hard X-ray bursts may in general be too short-lived for much K alpha emission. It may be noted that sulfur K alpha emission in particular depends sensitively on the lower-energy limit of the nonthermal electron spectrum, assuming such a sharply defined boundary exists. During soft X-ray bursts, when temperatures of a few 10 to the 7th power K are obtained, K alpha emission from certain iron ions, specifically Fe XVIII-XXIII, may be important.

  3. Structure of the Co and FeK alpha(3,4) Satellite Spectra

    SciTech Connect

    Daimant,R.; Sharon, R.; Caliebe, W.; Kao, C.; Deutsch, M.

    2006-01-01

    The K{alpha}{sub 3,4} satellite spectra, originating in the [1s2p]{sup -1}{yields} [2p]{sup -2} transition, were measured with high resolution for Co and Fe, using photoexcitation by tunable monochromatized synchrotron radiation. Fits to a phenomenological sum of Voigt functions and to ab initio relativistic Dirac-Fock-calculated spectra resolved the structure underlying the spectra. The dependence of the satellites' intensity on the excitation energy yielded accurate values for the excitation thresholds. The shake-theory-based Thomas model was found to deviate from the measured intensities, indicating near-threshold major contributions from non-shake excitation processes, such as the knockout, or 'two step one,' effect.

  4. Fluorescent excitation of photospheric Fe K-alpha emission during solar flares

    NASA Technical Reports Server (NTRS)

    Parmar, A. N.; Culhane, J. L.; Rapley, C. G.; Phillips, K. J. H.; Wolfson, C. J.; Acton, L. W.; Dennis, B. R.

    1982-01-01

    The Bent Crystal Spectrometer on the NASA Solar Maximum Mission satellite provides high spectral and temporal resolution observations of the Fe K-alpha lines. Analyses have been conducted of spectra from almost 50 solar flares that occurred during 1980. These data strongly support fluorescent excitation of photospheric iron by photons of E greater than 7.11 keV emitted by the hot coronal plasma produced during the flare. After comparison of the data with a model, the observed K-alpha line widths are discussed along with estimates of the size of the emitting region, the height of the coronal source and the photospheric iron abundance.

  5. XMM-Newton Observation of Fe K(alpha) Emission from a BAL QSO: Mrk 231

    NASA Technical Reports Server (NTRS)

    Turner, T. J.; Kraemer, S. B.

    2003-01-01

    We present results from a 20 ksec XMM-Newton observation of Mrk 231. EPIC spectral data reveal strong line emission due to Fe K alpha, which has rarely been detected in this class, as BAL QSOs are very faint in the X-ray band. The line energy is consistent with an origin in neutral Fe. The width of the line is equivalent to a velocity dispersion approximately 18,000 kilometers per second and thus the line may be attributed to transmission and/or reflection from a distribution of emitting clouds. If, instead, the line originates in the accretion disk then the line strength and flat X-ray continuum support some contribution from a reflected component, although the data disfavor a model where the hard X-ray band is purely reflected X-rays. The line parameters are similar to those obtained for the Fe Ka line detected in another BAL QSO, H1413 + 117.

  6. 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)

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

    2008-11-01

    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.

  7. The excitation of the iron K-alpha feature in solar flares

    NASA Technical Reports Server (NTRS)

    Emslie, A. G.; Phillips, K. J. H.; Dennis, B. R.

    1986-01-01

    The relationship between the hard X-ray photon spectrum and the flux of iron K-alpha emission in a thick-target electron bombardment model is evaluated. Results are presented for various power-law hard X-ray spectra. These results are applied to two events observed with the Hard X-Ray Burst Spectrometer and the K-alpha channel of the X-Ray Polychromator Bent Crystal Spectrometer on the Solar Maximum Mission satellite. For one of the events, on March 29, 1980, at 09:18 UT, the K-alpha flux predicted for a thick-target nonthermal process is significant compared to the background fluorescent component, and the data are indeed consistent with an enhancement of the predicted amount. For the other event, on October 14, 1980 at 0.6:09 UT, the hard X-ray spectrum is so steep that no significant K-alpha flux is predicted for this process, and no enhancement is seen. It is concluded that the agreement between the predicted K-alpha flux and the observed magnitude of the K-alpha enhancement above the fluorescent background at the time of the large hard X-ray bursts lends support to a thick-target nonthermal interpretation of impulsive hard X-ray emission in solar flares.

  8. High-resolution measurements of the K-alpha spectra of low-ionizationm species of iron: A new spectral signature of nonequilibrium ionization conditions in young supernova remnants

    NASA Technical Reports Server (NTRS)

    Decaux, V.; Beiersdorfer, P.; Osterheld, A.; Chen, M.; Kahn, S. M.

    1995-01-01

    We present the first systematic laboratory measurements of high-resolution K-alpha spectra of intermediate ions of iron, Fe X-XVII. These lines are not produced in collisional equilibrium plasmas because of the relevant charge states cannot exist at the high electron temperatures required for appreciable excitation of the K-alpha transitions. However, they can provide excellent spectral diagnostics for nonequilibrium ionization conditions, such the ionizing plasmas of young supernova remnants. To facilitate the line identifications, we compare our spectra with theoretical atomic calculations performed using multiconfiguration parametric potential and Dirac-Fock atomic codes. Our measurements also allow direct comparison with time-dependent ionization balance calculations for ionizing plasmas, and good agreement is found.

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

    SciTech Connect

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

    2010-10-15

    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 10{sup 17} to above 10{sup 19} W/cm{sup 2}. 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.

  10. K{alpha} satellite transitions in elements with 12{<=}Z{<=}30 produced by electron incidence

    SciTech Connect

    Limandri, Silvina P.; Carreras, Alejo C.; Trincavelli, Jorge C.; Bonetto, Rita D.

    2010-09-15

    The emission of x-ray satellite lines in the K{alpha} region of Mg, Si, Sc, Ti, Cr, Fe, Ni, and Zn induced by electron incidence was studied by means of wavelength dispersive spectroscopy. The satellite lines studied were K{alpha}{sup '}, K{alpha}{sub 3}, K{alpha}{sub 4}, K{alpha}{sub 5}, K{alpha}{sub 6}, and two transitions denoted here as K{alpha}{sub 22} and K{alpha}{sub 12}. Energy shifts with respect to the main K{alpha}{sub 1} diagram line and transition probabilities relative to the whole K{alpha} group were determined for a number of lines through a careful spectral processing. The dependence of these parameters, as well as of the K{beta}:K{alpha} intensity ratio, on the atomic number was compared with previous experimental and theoretical determinations when available. A discussion about the different mechanisms responsible for vacancy creation involved in the production of double-ionization satellites was performed in the light of the results obtained. Finally, the behavior of the satellite intensities as a function of the incidence energy was discussed for silicon.

  11. K-alpha X-rays from cosmic ray oxygen. [Detection and calculation of equilibrium charge fractions

    NASA Technical Reports Server (NTRS)

    Pravdo, S. H.; Boldt, E. A.

    1975-01-01

    Equilibrium charge fractions are calculated for subrelativistic cosmic ray oxygen ions in the interstellar medium. These are used to determine the expected flux of K-alpha rays arising from atomic processes for a number of different postulated interstellar oxygen spectra. Relating these results to the diffuse X-ray background measured at the appropriate energy level suggests an observable line feature. If the flux of low energy cosmic ray oxygen is sufficiently large, K-alpha X-ray line emission from these nuclei will comprise a significant fraction of the total diffuse flux at approximately 0.6 keV. A satellite borne detector with a resolution greater than 30 percent could observe this feature if the subrelativistic interstellar cosmic ray oxygen spectrum is as large as certain theoretical estimates expressed in the text.

  12. Diffuse emission and pathological Seyfert spectra

    NASA Technical Reports Server (NTRS)

    Halpern, Jules P.

    1995-01-01

    In this annual ROSAT status report, the diffuse emission and spectra from Seyfert galaxies are examined. Three papers are presented and their contents include the soft x-ray properties and spectra of a binary millisecond pulsar, the PSPC and HRI observations of a Starburst/Seyfert 2 Galaxy, and an analysis of the possibility of x-ray luminous starbursts in the Einstein Medium Sensitivity Survey.

  13. 12.6 keV Kr K-alpha X-ray Source For High Energy Density Physics Experiments

    SciTech Connect

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

    2008-04-22

    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.

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

    SciTech Connect

    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.

    2006-08-15

    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.

  15. Thermal Emission and Albedo Spectra of Super Earths with Flat Transmission Spectra

    E-print Network

    Morley, Caroline V; Marley, Mark S; Zahnle, Kevin; Line, Michael; Kempton, Eliza; Lewis, Nikole; Cahoy, Kerri

    2015-01-01

    Planets larger than Earth and smaller than Neptune are some of the most numerous in the galaxy, but observational efforts to understand this population have proved challenging because optically thick clouds or hazes at high altitudes obscure molecular features (Kreidberg et al. 2014b). We present models of super Earths that include thick clouds and hazes and predict their transmission, thermal emission, and reflected light spectra. Very thick, lofted clouds of salts or sulfides in high metallicity (1000x solar) atmospheres create featureless transmission spectra in the near-infrared. Photochemical hazes with a range of particle sizes also create featureless transmission spectra at lower metallicities. Cloudy thermal emission spectra have muted features more like blackbodies, and hazy thermal emission spectra have emission features caused by an inversion layer at altitudes where the haze forms. Close analysis of reflected light from warm (~400-800 K) planets can distinguish cloudy spectra, which have moderate ...

  16. On the importance of satellite lines to the He-like K ALPHA complex and the G ratio for calcium, iron, and nickel

    E-print Network

    J. Oelgoetz; C. J. Fontes; H. L. Zhang; S. N. Nahar; A. K. Pradhan

    2008-11-13

    New, more detailed calculations of the emission spectra of the He-like K ALPHA complex of calcium, iron and nickel have been carried out using data from both distorted-wave and R-matrix calculations. The value of the GD ratio (an extended definition of the G ratio that accounts for the effect of resolved and unresolved satellite lines) is significantly enhanced at temperatures below the temperature of He-like maximum abundance. Furthermore it is shown that satellite lines are important contributors to the GD ratio such that GD/G>1 at temperatures well above the temperature of maximum abundance. These new calculations demonstrate, with an improved treatment of the KLn (n>=3) satellite lines, that K ALPHA satellite lines need to be included in models of He like spectra even at relatively high temperatures. The excellent agreement between spectra and line ratios calculated from R-matrix and distorted-wave data also confirms the validity of models based on distorted-wave data for highly charged systems, provided the effect of resonances are taken into account as independent processes.

  17. Retrieval of constituent mixing ratios from limb thermal emission spectra

    NASA Technical Reports Server (NTRS)

    Shaffer, William A.; Kunde, Virgil G.; Conrath, Barney J.

    1988-01-01

    An onion-peeling iterative, least-squares relaxation method to retrieve mixing ratio profiles from limb thermal emission spectra is presented. The method has been tested on synthetic data, containing various amounts of added random noise for O3, HNO3, and N2O. The retrieval method is used to obtain O3 and HNO3 mixing ratio profiles from high-resolution thermal emission spectra. Results of the retrievals compare favorably with those obtained previously.

  18. Thermal Emission and Reflected Light Spectra of Super Earths with Flat Transmission Spectra

    NASA Astrophysics Data System (ADS)

    Morley, Caroline V.; Fortney, Jonathan J.; Marley, Mark S.; Zahnle, Kevin; Line, Michael; Kempton, Eliza; Lewis, Nikole; Cahoy, Kerri

    2015-12-01

    Planets larger than Earth and smaller than Neptune are some of the most numerous in the galaxy, but observational efforts to understand this population have proved challenging because optically thick clouds or hazes at high altitudes obscure molecular features. We present models of super Earths that include thick clouds and hazes and predict their transmission, thermal emission, and reflected light spectra. Very thick, lofted clouds of salts or sulfides in high metallicity (1000× solar) atmospheres create featureless transmission spectra in the near-infrared. Photochemical hazes with a range of particle sizes also create featureless transmission spectra at lower metallicities. Cloudy thermal emission spectra have muted features more like blackbodies, and hazy thermal emission spectra have emission features caused by an inversion layer at altitudes where the haze forms. Close analysis of reflected light from warm (˜400-800 K) planets can distinguish cloudy spectra, which have moderate albedos (0.05-0.20), from hazy models, which are very dark (0.0-0.03). Reflected light spectra of cold planets (˜200 K) accessible to a space-based visible light coronagraph will have high albedos and large molecular features that will allow them to be more easily characterized than the warmer transiting planets. We suggest a number of complementary observations to characterize this population of planets, including transmission spectra of hot (? 1000 K) targets, thermal emission spectra of warm targets using the James Webb Space Telescope, high spectral resolution (R ˜ 105) observations of cloudy targets, and reflected light spectral observations of directly imaged cold targets. Despite the dearth of features observed in super Earth transmission spectra to date, different observations will provide rich diagnostics of their atmospheres.

  19. Extreme ultraviolet emission spectra of Gd and Tb ions

    SciTech Connect

    Kilbane, D.; O'Sullivan, G.

    2010-11-15

    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.

  20. Observations of neutral iron emission in twilight spectra

    NASA Technical Reports Server (NTRS)

    Tepley, C. A.; Meriwether, J. W., Jr.; Walker, J. C. G.; Mathews, J. D.

    1981-01-01

    A method is presented for the analysis of twilight airglow spectra that may be contaminated by atmospheric continuum emission of unknown brightness. The necessity of correcting for this continuum emission when measuring weak airglow features in twilight is illustrated by application of the method to the neutral iron line at 3860 A.

  1. High-resolution studies of atmospheric IR emission spectra

    NASA Technical Reports Server (NTRS)

    Murcray, F. J.; Murcray, F. H.; Goldman, A.; Blatherwick, R. D.; Murcray, D. G.

    1991-01-01

    Atmospheric emission spectra obtained with two different spectrometer systems are presented. The first system (the BOMEM Michelson interferometer) is designed for emission work. Spectra were obtained under adverse conditions in the Antarctic, and are still of good absolute accuracy. The second system (a modified Bruker Instruments IFS120 very high spectral resolution interferometer) demonstrates the sensitivity that can be achieved even at higher spectral resolution. This system shows that mid-IR atmospheric emission spectra can be obtained with a good SNR in a reasonable length of time at a relatively high resolution. A properly designed high resolution system should achieve high accuracy, sensitivity, and resolution, thereby permitting measurements of many atmospheric constituents when solar spectra cannot be obtained.

  2. SMM observations of K-alpha radiation from fluorescence of photospheric iron by solar flare X-rays

    NASA Technical Reports Server (NTRS)

    Parmar, A. N.; Culhane, J. L.; Rapley, C. G.; Wolfson, C. J.; Acton, L. W.; Phillips, K. J. H.; Dennis, B. R.

    1984-01-01

    High-resolution Fe K-alpha spectra near 1.94 A observed during solar flares with the Bent Crystal Spectrometer on the Solar Maximum Mission are presented. The evidence for two possible excitation mechanisms, electron impact and fluorescence, is examined. It is found that the fluorescence mechanism satisfactorily describes the results, while the observations do not support electron collisional excitation of the Fe K-alpha transitions in low ionization stages (II-XII) of iron. Using Bai's model of the fluorescent excitation process, the photospheric iron abundance relative to that of hydrogen is estimated to be 5-6 x 10 to the -5th. The mean height of the soft X-ray source producing the K-alpha fluorescence is calculated on the basis of this model for about 40 large flares. The solar K-alpha lines are found to be about 25 percent wider than those measured in the laboratory. Weak line features observed at wavelengths shorter than that of the K-alpha lines are discussed.

  3. The sharpness of gamma-ray burst prompt emission spectra

    NASA Astrophysics Data System (ADS)

    Yu, Hoi-Fung; van Eerten, Hendrik J.; Greiner, Jochen; Sari, Re'em; Narayana Bhat, P.; von Kienlin, Andreas; Paciesas, William S.; Preece, Robert D.

    2015-11-01

    Context. We study the sharpness of the time-resolved prompt emission spectra of gamma-ray bursts (GRBs) observed by the Gamma-ray Burst Monitor (GBM) on board the Fermi Gamma-ray Space Telescope. Aims: We aim to obtain a measure of the curvature of time-resolved spectra that can be compared directly to theory. This tests the ability of models such as synchrotron emission to explain the peaks or breaks of GBM prompt emission spectra. Methods: We take the burst sample from the official Fermi GBM GRB time-resolved spectral catalog. We re-fit all spectra with a measured peak or break energy in the catalog best-fit models in various energy ranges, which cover the curvature around the spectral peak or break, resulting in a total of 1113 spectra being analyzed. We compute the sharpness angles under the peak or break of the triangle constructed under the model fit curves and compare them to the values obtained from various representative emission models: blackbody, single-electron synchrotron, synchrotron emission from a Maxwellian or power-law electron distribution. Results: We find that 35% of the time-resolved spectra are inconsistent with the single-electron synchrotron function, and 91% are inconsistent with the Maxwellian synchrotron function. The single temperature, single emission time, and location blackbody function is found to be sharper than all the spectra. No general evolutionary trend of the sharpness angle is observed, neither per burst nor for the whole population. It is found that the limiting case, a single temperature Maxwellian synchrotron function, can only contribute up to % of the peak flux. Conclusions: Our results show that even the sharpest but non-realistic case, the single-electron synchrotron function, cannot explain a large fraction of the observed GRB prompt spectra. Because any combination of physically possible synchrotron spectra added together will always further broaden the spectrum, emission mechanisms other than optically thin synchrotron radiation are likely required in a full explanation of the spectral peaks or breaks of the GRB prompt emission phase. Appendices are available in electronic form at http://www.aanda.org

  4. Excitation and emission spectra of jet-cooled naphthylmethyl radicals.

    PubMed

    Chalyavi, Nahid; Troy, Tyler P; Nakajima, Masakazu; Gibson, Bligh A; Nauta, Klaas; Sharp, Robert G; Kable, Scott H; Schmidt, Timothy W

    2011-07-14

    Gas phase excitation and emission spectra of three naphthylmethyl radical chromophores are presented. These resonance-stabilized species, 1-naphthylmethyl, 2-naphthylmethyl, and ?-acenaphthenyl, each possessing an sp(2) carbon adjacent to a naphthalene moiety, are studied by resonant two-color two-photon ionization, laser induced fluorescence, and dispersed fluorescence spectroscopy. Identification of the radicals is made through a combination of dispersed fluorescence and density functional theory calculations. All three species possess spectra in the 580 nm region. The possible relevance to unidentified spectroscopic features such as the diffuse interstellar bands and emission from the Red Rectangle nebula is discussed. PMID:21648397

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

    SciTech Connect

    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.

    2005-01-01

    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.

  6. AO14: Detection of Aircraft Emission Signatures in Atmospheric Spectra

    E-print Network

    Oxford, University of

    AO14: Detection of Aircraft Emission Signatures in Atmospheric Spectra Supervisors: Dr A. Dudhia, Dr C. Piccolo Candidate Number: 26912 Abstract Commercial jet aircraft are known to have both industry predicted to grow at a rate of 5% per year until at least 2015, a study of the impact of aircraft

  7. Spreadsheet-Based Program for Simulating Atomic Emission Spectra

    ERIC Educational Resources Information Center

    Flannigan, David J.

    2014-01-01

    A simple Excel spreadsheet-based program for simulating atomic emission spectra from the properties of neutral atoms (e.g., energies and statistical weights of the electronic states, electronic partition functions, transition probabilities, etc.) is described. The contents of the spreadsheet (i.e., input parameters, formulas for calculating…

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

    SciTech Connect

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

    2006-11-21

    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.

  9. A CORRELATION BETWEEN STELLAR ACTIVITY AND HOT JUPITER EMISSION SPECTRA

    SciTech Connect

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

    2010-09-10

    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 and 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 {alpha} 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 {mu}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.

  10. THE CORES OF THE Fe K{alpha} LINES IN ACTIVE GALACTIC NUCLEI: AN EXTENDED CHANDRA HIGH ENERGY GRATING SAMPLE

    SciTech Connect

    Shu, X. W.; Wang, J. X.; Yaqoob, T. E-mail: yaqoob@pha.jhu.edu

    2010-04-01

    We extend the study of the core of the Fe K{alpha} emission line at {approx}6.4 keV in Seyfert galaxies reported by Yaqoob and Padmanabhan using a larger sample observed by the Chandra high-energy grating (HEG). The sample consists of 82 observations of 36 unique sources with z < 0.3. Whilst heavily obscured active galactic nuclei are excluded from the sample, these data offer some of the highest precision measurements of the peak energy of the Fe K{alpha} line, and the highest spectral resolution measurements of the width of the core of the line in unobscured and moderately obscured (N {sub H} < 10{sup 23} cm{sup -2}) Seyfert galaxies to date. From an empirical and uniform analysis, we present measurements of the Fe K{alpha} line centroid energy, flux, equivalent width (EW), and intrinsic width (FWHM). The Fe K{alpha} line is detected in 33 sources, and its centroid energy is constrained in 32 sources. In 27 sources, the statistical quality of the data is good enough to yield measurements of the FWHM. We find that the distribution in the line centroid energy is strongly peaked around the value for neutral Fe, with over 80% of the observations giving values in the range 6.38-6.43 keV. Including statistical errors, 30 out of 32 sources ({approx}94%) have a line centroid energy in the range 6.35-6.47 keV. The mean EW, among the observations in which a non-zero lower limit could be measured, was 53 {+-} 3 eV. The mean FWHM from the subsample of 27 sources was 2060 {+-} 230 km s{sup -1}. The mean EW and FWHM are somewhat higher when multiple observations for a given source are averaged. From a comparison with the H{beta} optical emission-line widths (or, for one source, Br{alpha}), we find that there is no universal location of the Fe K{alpha} line-emitting region relative to the optical broad-line region (BLR). In general, a given source may have contributions to the Fe K{alpha} line flux from parsec-scale distances from the putative black hole, down to matter a factor {approx}2 closer to the black hole than the BLR. We confirm the presence of the X-ray Baldwin effect, an anti-correlation between the Fe K{alpha} line EW and X-ray continuum luminosity. The HEG data have enabled isolation of this effect to the narrow core of the Fe K{alpha} line.

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

    SciTech Connect

    Westover, B.; Beg, F. N.; MacPhee, A.; Chen, C.; Hey, D.; Maddox, B.; Park, H.-S.; Remington, B.; Ma, T.

    2010-08-15

    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.

  12. Hot Electron Generation and Transport Using K(alpha) Emission

    SciTech Connect

    Akli, K U; Stephens, R B; Key, M H; Bartal, T; Beg, F N; Chawla, S; Chen, C D; Fedosejevs, R; Freeman, R R; Friesen, H; Giraldez, E; Green, J S; Hey, D S; Higginson, D P; Hund, J; Jarrott, L C; Kemp, G E; King, J A; Kryger, A; Lancaster, K; LePape, S; Link, A; Ma, T; Mackinnon, A J; MacPhee, A G; McLean, H S; Murphy, C; Norreys, P A; Ovchinnikov, V; Patel, P K; Ping, Y; Sawada, H; Schumacher, D; Theobald, W; Tsui, Y Y; Van Woerkom, L D; Wei, M S; Westover, B; Yabuuchi, T

    2009-10-15

    We have conducted experiments on both the Vulcan and Titan laser facilities to study hot electron generation and transport in the context of fast ignition. Cu wires attached to Al cones were used to investigate the effect on coupling efficiency of plasma surround and the pre-formed plasma inside the cone. We found that with thin cones 15% of laser energy is coupled to the 40{micro}m diameter wire emulating a 40{micro}m fast ignition spot. Thick cone walls, simulating plasma in fast ignition, reduce coupling by x4. An increase of prepulse level inside the cone by a factor of 50 reduces coupling by a factor of 3.

  13. X-ray emission and photoelectron spectra of Pr{sub 0.5}Sr{sub 0.5}MnO{sub 3}

    SciTech Connect

    Kurmaev, E.Z.; Korotin, M.A.; Galakhov, V.R.; Finkelstein, L.D.; Zabolotzky, E.I.; Efremova, N.N.; Lobachevskaya, N.I.; Stadler, S.; Ederer, D.L.; Callcott, T.A.; Zhou, L.; Moewes, A.; Bartkowski, S.; Neumann, M.; Matsuno, J.; Mizokawa, T.; Fujimori, A.; Mitchell, J.

    1999-05-01

    The results of measurements of x-ray photoelectron (XPS), x-ray emission (XES), and x-ray absorption spectra and local spin-density approximation band structure (LSDA) calculations of Pr{sub 0.5}Sr{sub 0.5}MnO{sub 3} are presented. The excitation energy dependence of Mn L{sub 2,3} and O K{alpha} x-ray emission spectra of Pr{sub 0.5}Sr{sub 0.5}MnO{sub 3} is measured using tunable synchrotron radiation. The XES measurements yielded no photon energy dependence for the O K{alpha} spectra, but the Mn L{sub 2,3} spectra yielded inelastic scattering losses of 2 and 6 eV, corresponding to features in the structure of the occupied part of the valence band. Comparing XPS and XES measurements with LSDA band-structure calculations, one concludes that the electronic structure of the compound consists mainly of Mn 3d and O 2p states. States of 3d character localized at the Mn site predominate near the top of the valence band (VB). Some differences in the Mn 3d distribution in this part of the XPS valence band and Mn L{sub 3} XES with {ital d} symmetry due to spin-selection rules that govern the Mn L{sub 3} XES. In addition, the Mn 3d states distribution is hybridized with the O 2p part of the VB. Mn L{sub 3} XES spectra were determined relative to the Fermi energy by assuming normal x-ray emission begins from the lowest level of the p{sup 5}d{sup n+1}L intermediate state (which is the Mn 2p ionizatation threshold). From the local spin-density approximation, the orbital character of the Mn 3d electrons can be assigned e{sub g} symmetry at the top of the valence band T{sub 2g} in the central part of the VB, and equal contributions of e{sub g} and t{sub 2g} states at the bottom of the valence band. {copyright} {ital 1999} {ital The American Physical Society}

  14. Structural Effects of Oncogenic PI3K alpha Mutations

    SciTech Connect

    S Gabelli; C Huang; D Mandelker; O Schmidt-Kittler; B Vogelstein; L Amzel

    2011-12-31

    Physiological activation of PI3K{alpha} is brought about by the release of the inhibition by p85 when the nSH2 binds the phosphorylated tyrosine of activated receptors or their substrates. Oncogenic mutations of PI3K{alpha} result in a constitutively activated enzyme that triggers downstream pathways that increase tumor aggressiveness and survival. Structural information suggests that some mutations also activate the enzyme by releasing p85 inhibition. Other mutations work by different mechanisms. For example, the most common mutation, His1047Arg, causes a conformational change that increases membrane association resulting in greater accessibility to the substrate, an integral membrane component. These effects are examples of the subtle structural changes that result in increased activity. The structures of these and other mutants are providing the basis for the design of isozyme-specific, mutation-specific inhibitors for individualized cancer therapies.

  15. Investigating the origin of emissivity features in airless body spectra

    NASA Astrophysics Data System (ADS)

    Greenhagen, B. T.; Bowles, N. E.; Thomas, I.; Donaldson Hanna, K. L.

    2013-12-01

    It has long been noted that mid-infrared emissivity features remote observations of airless bodies do not generally match reflectance and ambient thermal emission laboratory measurements. Recently Vernazza et al., (2012) conducted reflectance experiments and successfully reproduced spectral differences by doping a fine (<30 micron) particulate samples of meteorite and/or minerals with KBr (potassium bromide) powder, which is transparent in the infrared. Their results suggest that porosity and/or cavity effects are significant in modifying the observed spectra of asteroids and derived values of surface thermal inertia. At similar wavelengths, the lunar community has long supported the theory that radiative transfer was a driving phenomenon through the creation of strong thermal gradients in the upper 100 microns of a particulate surface (e.g. Logan et al., 1973; Henderson et al., 1995). These thermal gradients are steep within the depth of thermal emission causing a strong wavelength dependence to the observed thermal emission spectrum. For example, strong absorptions like Reststrahlen Bands emit from the colder, shallower surface while strongly transparent features such as the Christiansen Feature emit from the warmer, deeper surface. To study these effects, we have built simulated airless body thermal emission chambers at University of Oxford and JPL (Thomas et al., 2012). In this study we investigate both radiative transfer and porosity phenomenon by measuring KBr-doped samples in reflectance and both ambient and simulated airless body emission.

  16. Terrestrial FeO Continuum Emission Observed in Sky Spectra

    NASA Astrophysics Data System (ADS)

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

    2011-01-01

    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

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

    PubMed

    Bazin, Cyril; Koutchmy, Serge

    2013-05-01

    At the time of the two last solar total eclipses of August 1st, 2008 in Siberia and July 11th, 2010 in French Polynesia, high frame rate CCD flash spectra were obtained. These eclipses occurred in quiet Sun period and after. The slitless flash spectra show two helium shells, in the weak Paschen ? 4686 Å line of the ionized helium HeII and in the neutral helium HeI line at 4713 Å. The extensions of these helium shells are typically 3 Mm. In prominences, the extension of the interface with the corona is much more extended. The observations and analysis of these lines can properly be done only in eclipse conditions, when the intensity threshold reaches the coronal level, and the parasitic scattered light is virtually zero. Under the layers of 1 Mm above the limb, many faint low FIP lines were also seen in emission. These emission lines are superposed on the continuum containing absorption lines. The solar limb can be defined using the weak continuum appearing between the emission lines at the time of the second and third contact. The variations of the singly ionized iron line, the HeI and HeII lines and the continuum intensity are analyzed. The intensity ratio of ionized to neutral helium is studied for evaluating the ionization rate in low layers up to 2 Mm and also around a prominence. PMID:25685435

  18. Gravitational redshift of emission lines in the AGN spectra

    NASA Astrophysics Data System (ADS)

    Bon, Nataša; Bon, Edi; Marziani, Paola; Jovanovi?, Predrag

    2015-12-01

    The detection of gravitationally redshifted optical emission lines has been reported just for a few active galaxies. In this paper we give a short overview of studies that analyzed or exploited the detection of the gravitational redshift in optical AGN spectra. In addition, we tested the consistency of gravitational redshift as the physical origin of the redward shifts observed in their spectra using a sample of {?}50 Hamburg-ESO intermediate to high redshift quasars that are among the most luminous quasars known (10^{47} ? L ? 10^{48} erg/s), and are expected to host very massive black holes. To this aim we modeled the line profile with accretion disk models around a black hole.

  19. Emissivity spectra estimated with the MaxEnTES algorithm

    NASA Astrophysics Data System (ADS)

    Barducci, A.; Guzzi, D.; Lastri, C.; Nardino, V.; Pippi, I.; Raimondi, V.

    2014-10-01

    Temperature and Emissivity Separation (TES) applied to multispectral or hyperspectral Thermal Infrared (TIR) images of the Earth is a relevant issue for many remote sensing applications. The TIR spectral radiance can be modeled by means of the well-known Planck's law, as a function of the target temperature and emissivity. The estimation of these target's parameters (i.e. the Temperature Emissivity Separation, aka TES) is hindered by the circumstance that the number of measurements is less than the unknown number. Existing TES algorithms implement a temperature estimator in which the uncertainty is removed by adopting some a priori assumption that conditions the retrieved temperature and emissivity. Due to its mathematical structure, the Maximum Entropy formalism (MaxEnt) seems to be well suited for carrying out this complex TES operation. The main advantage of the MaxEnt statistical inference is the absence of any external hypothesis, which is instead characterizes most of the existing the TES algorithms. In this paper we describe the performance of the MaxEnTES (Maximum Entropy Temperature Emissivity Separation) algorithm as applied to ten TIR spectral channels of a MIVIS dataset collected over Italy. We compare the temperature and emissivity spectra estimated by this algorithm with independent estimations achieved with two previous TES methods (the Grey Body Emissivity (GBE), and the Model Emittance Calculation (MEC)). We show that MaxEnTES is a reliable algorithm in terms of its higher output Signal-to-Noise Ratio and the negligibility of systematic errors that bias the estimated temperature in other TES procedures.

  20. Interpreting the ionization sequence in AGN emission-line spectra

    NASA Astrophysics Data System (ADS)

    Richardson, Chris T.; Allen, James T.; Baldwin, Jack A.; Hewett, Paul C.; Ferland, Gary J.

    2014-01-01

    We investigate the physical cause of the great range in the ionization level seen in the spectra of narrow-lined active galactic nuclei (AGN). We used a recently developed technique called mean field independent component analysis to identify examples of individual Sloan Digital Sky Survey galaxies whose spectra are not dominated by emission due to star formation (SF), which we therefore designate as AGN. We assembled high signal-to-noise ratio (S/N) composite spectra of a sequence of these AGN defined by the ionization level of their narrow-line regions (NLR), and extending down to very low ionization cases. We then used a local optimally emitting cloud (LOC) model to fit emission-line ratios in this AGN sequence, including the weak lines that can be measured only in the co-added spectra. These weak line ratios provide consistency checks on the density, temperature, abundances and ionizing continuum of Seyfert galaxies determined from strong-line ratios. After integrating over a wide range of clouds at different radii and densities, our models indicate that the radial extent of the NLR is the major parameter in determining the position of higher to moderate ionization AGN along our sequence. This provides a physical interpretation for their systematic variation. Higher ionization AGN contain optimally emitting clouds that are more concentrated towards the central continuum source than in lower ionization AGN. Our LOC models indicate that for the special set of objects that lie on our AGN sequence, the ionizing luminosity is anti-correlated with the NLR ionization level, and hence anticorrelated with the radial concentration and actual physical extent of the NLR. A possible interpretation that deserves further exploration is that the ionization sequence might be an age sequence where low ionization objects are older and have systematically cleared out their central regions by radiation pressure. We consider the alternative that our AGN sequence instead represents a mixing curve combining SF and AGN spectra in different proportions, but argue that while many galaxies in fact do have this type of composite spectra, our AGN sequence appears to be a special set of objects with negligible SF excitation.

  1. Spectra of hybrid synchrotron emission in hot black hole winds

    NASA Astrophysics Data System (ADS)

    Hayakawa, Ken; Fukue, Jun

    2015-10-01

    We solve radiative transfer to obtain the hybrid synchrotron spectra from a hot, optically thin black hole wind, by integrating the radiative transfer equation in the comoving frame and considering the relativistic effect of wind flow as well as the emission and absorption along the line-of-sight. We find two primary characteristics in the hybrid model: (1) a shoulder at low frequencies and (2) a power-law tail at high frequencies. Even if only 10-4 of the total electron energy is injected as non-thermal electrons, higher luminosity can be produced compared to the pure thermal model. Thus, there is a large difference between the pure thermal model and the hybrid one. In addition, as the wind velocity becomes large, the thermal peak of the comoving spectra shifts toward the high-frequency regime, due to the relativistic Doppler effect. As the wind velocity increases, on the other hand, the thermal peak of the observed spectra shifts toward the low-frequency regime, due to the redshifted part in the far side and limb side.

  2. A Thermal Infrared Emission Spectra Library for Unpowdered Meteorites

    NASA Astrophysics Data System (ADS)

    Ashley, J. W.; Christensen, P. R.

    2007-12-01

    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 and the NASA Antarctic Meteorite Working Group, and from private collections. The database was prepared to aid in the on-going detection and interpretation of meteorites on Mars using the Miniature Thermal Emission Spectrometer (Mini-TES) instruments on both Mars Exploration Rovers. It therefore includes several specimens of low, moderate, and high weathering intensities, reflecting different levels of water exposure in desert and non-desert environments. Unweathered falls are also considered. Samples represent all three chondrite classes, stony irons (mesosiderites and pallasites), and select achondrites. Special consideration is given to dust-covered iron-nickel meteorites as part of a separate study designed to evaluate the Mini-TES spectra of iron-nickel meteorites on Mars. All samples were analyzed at or near a temperature of 80° C using a modified Nicolet Nexus 670 FT-IR spectrometer at the Mars Space Flight Facility at Arizona State University. Data were collected within the 2000 to 200 wavenumber (5 to 50 microns) mid-infrared range. The results show that many meteorite types display moderate to wide variability in the depth and position of prominent absorption features, making them easily distinguishable from each other. Most previous meteorite spectroscopy studies have either focused on near-infrared reflectance spectra [e.g. 1], and/or involved powdered samples to represent asteroid regoliths in the mid-infrared [e.g. 2 & 3]. Particle size- related issues are often at the heart of interpretation of asteroid spectroscopic studies in the mid-infrared [4]. However, the high-resolution Itokawa imaging results of the Hayabusa mission have shown that not all asteroid surfaces are dominated by powdered materials [e.g. 5]. It is therefore anticipated that whole-rock, mid-infrared emission spectra may serve a further purpose in studies conducted with Spitzer Space Telescope and other space-born observatories equipped with mid-infrared detectors. The library will therefore continue to be augmented with additional spectra, to include unweathered carbonaceous chondrites and achondrites at a minimum. All spectra are available through the Arizona State University Thermal Emission Spectral Library. References: [1] Sato K. and Miyamoto M. (1998) Antarctic Meteorite Research 11, 155-162. [2] Salisbury J.W. et al. (1991) NASA Technical Memorandum #4300, 262-204. [3] Dameron S.N. and Burbine T.H. (2006) LPSC XXXVII, abstract #1828. [4] Emery J.P. et al. (2006) Icarus 182, 496-512. [5] Miyamoto et al. (2007) Science 316, 1011- 1014.

  3. Neutron emission profiles and energy spectra measurements at JET

    NASA Astrophysics Data System (ADS)

    Giacomelli, L.; Conroy, S.; Belli, F.; Gorini, G.; Horton, L.; Joffrin, E.; Lerche, E.; Murari, A.; Popovichev, S.; Riva, M.; Syme, B.; JET EFDA Contributors

    2014-08-01

    The Joint European Toras (JET, Culham, UK) is the largest tokamak in the world. It is devoted to nuclear fusion experiments of magnetic confined Deuterium (D) or Deuterium-Tritium (DT) plasmas. JET has been upgraded over the years and recently it has also become a test facility of the components designed for ITER, the next step fusion machine under construction in Cadarache (France). JET makes use of many different diagnostics to measure the physical quantities of interest in plasma experiments. Concerning D or DT plasmas neutron production, various types of detectors are implemented to provide information upon the neutron total yield, emission profile and energy spectrum. The neutron emission profile emitted from the JET plasma poloidal section is reconstructed using the neutron camera (KN3). In 2010 KN3 was equipped with a new digital data acquisition system capable of high rate neutron measurements (<0.5 MCps). A similar instrument will be implemented on ITER and it is currently in its design phase. Various types of neutron spectrometers with different view lines are also operational on JET. One of them is a new compact spectrometer (KM12) based on organic liquid scintillating material which was installed in 2010 and implements a similar digital data acquisition system as for KN3. This article illustrates the measurement results of KN3 neutron emission profiles and KM 12 neutron energy spectra from the latest JET D experimental campaign C31.

  4. Analysis of neutral hydrogenic emission spectra in a tokamak

    NASA Astrophysics Data System (ADS)

    Ko, J.; Chung, J.; Jaspers, R. J. E.

    2015-10-01

    Balmer-? radiation by the excitation of thermal and fast neutral hydrogenic particles has been investigated in a magnetically confined fusion device, or tokamak, from the Korea Superconducting Tokamak Advanced Research (KSTAR). From the diagnostic point of view, the emission from thermal neutrals is associated with passive spectroscopy and that from energetic neutrals that are usually injected from the outside of the tokamak to the active spectroscopy. The passive spectroscopic measurement for the thermal Balmer-? emission from deuterium and hydrogen estimates the relative concentration of hydrogen in a deuterium-fueled plasma and therefore, makes a useful tool to monitor the vacuum wall condition. The ratio of hydrogen to deuterium obtained from this measurement qualitatively correlates with the energy confinement of the plasma. The Doppler-shifted Balmer-? components from the fast neutrals features the spectrum of the motional Stark effect (MSE) which is an essential principle for the measurement of the magnetic pitch angle profile. Characterization of this active MSE spectra, especially with multiple neutral beam lines crossing along the observation line of sight, has been done for the guideline of the multi-ion-source heating beam operation and for the optimization of the narrow bandpass filters that are required for the polarimeter-based MSE diagnostic system under construction at KSTAR.

  5. Orbits and emission spectra from the 2014 Camelopardalids

    NASA Astrophysics Data System (ADS)

    Madiedo, José M.; Trigo-Rodríguez, Josep M.; Zamorano, Jaime; Izquierdo, Jaime; de Miguel, Alejandro Sánchez; Ocaña, Francisco; Ortiz, José L.; Espartero, Francisco; Morillas, Lorenzo G.; Cardeñosa, David; Moreno-Ibáñez, Manuel; Urzáiz, Marta

    2014-12-01

    We have analysed the meteor activity associated with meteoroids of fresh dust trails of Comet 209P/LINEAR, which produced an outburst of the Camelopardalid meteor shower (IAU code #451, CAM) in 2014 May. With this aim, we have employed an array of high-sensitivity CCD video devices and spectrographs deployed at 10 meteor observing stations in Spain in the framework of the Spanish Meteor Network. Additional meteoroid flux data were obtained by means of two forward-scatter radio systems. The observed peak zenithal hourly rate was much lower than expected, of around 20 meteors h-1. Despite of the small meteor flux in the optical range, we have obtained precise atmospheric trajectory, radiant and orbital information for 11 meteor and fireball events associated with this stream. The ablation behaviour and low tensile strength calculated for these particles reveal that Camelopardalid meteoroids are very fragile, mostly pristine aggregates with strength similar to that of the Orionids and the Leonids. The mineral grains seem to be glued together by a volatile phase. We also present and discuss two unique emission spectra produced by two Camelopardalid bright meteors. These suggest a non-chondritic nature for these particles, which exhibit Fe depletion in their composition.

  6. Fe X Emission Lines in Solar and Stellar Spectra

    NASA Astrophysics Data System (ADS)

    Foster, V. J.; Mathioudakis, M.; Keenan, F. P.; Drake, J. J.; Widing, K. G.

    1996-12-01

    Theoretical electron density sensitive emission line ratios involving Fe X 3s23p5-3s23p43d transitions in the 170-190 Å wavelength range are compared with observational data for a solar active region and flares, obtained during the Skylab mission, and Cen and Procyon observations from the Extreme Ultraviolet Explorer (EUVE) satellite. Electron densities derived from the majority of the ratios are consistent for the events but are in poor agreement with the values of Ne estimated from diagnostic lines in other species observed in the spectra, casting doubt on the accuracy of the theoretical line ratio calculations and, hence, the atomic data of Mohan et al. used in their derivation. At low Ne, the present ratios are significantly different from those of Young et al., while the latter imply densities that are in somewhat better agreement with densities derived from other diagnostics. This would appear to indicate that the electron impact excitation rates of Bhatia & Doschek adopted by Young et al. are to be preferred over the Mohan et al. results.

  7. Low energy particle composition. [energy spectra, particle emission - solar flares

    NASA Technical Reports Server (NTRS)

    Gloeckler, G.

    1975-01-01

    The energy spectra and composition of the steady or 'quiet-time' particle flux, whose origin is unknown was studied. Particles and photons which are associated with solar flares or active regions on the sun were also studied. Various detection techniques used to measure the composition and energy spectra of low energy particles are discussed. Graphs of elemental abundance and energy spectra are given.

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

    SciTech Connect

    Nikolaev, Ivan S.; Lodahl, Peter; Vos, Willem L.

    2005-05-15

    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.

  9. Special relativistic effects on the strength of the fluorescent K-alpha iron line from black hole accretion disks

    E-print Network

    C. S. Reynolds; A. C. Fabian

    1997-07-07

    The broad iron K$\\alpha$ emission line, commonly seen in the X-ray spectrum of Seyfert nuclei, is thought to originate when the inner accretion disk is illuminated by an active disk-corona. We show that relative motion between the disk and the X-ray emitting material can have an important influence on the observed equivalent width (EW) of this line via special relativistic aberration and Doppler effects. We suggest this may be relevant to understanding why the observed EW often exceeds the prediction of the standard X-ray reflection model. Several observational tests are suggested that could disentangle these special relativistic effects from iron abundance effects.

  10. Seeing Through the Clouds: Thermal Emission and Reflected Light Spectra of Super-Earths with Flat Transmission Spectra

    NASA Astrophysics Data System (ADS)

    Morley, Caroline; Fortney, Jonathan J.; Marley, Mark; Zahnle, Kevin; Line, Michael R.; Kempton, Eliza M.-R.; Lewis, Nikole K.; Cahoy, Kerri

    2015-12-01

    Vast resources have been dedicated to characterizing the handful of planets with radii between Earth’s and Neptune’s that are accessible to current telescopes. Observations of their transmission spectra have been inconclusive and do not constrain their atmospheric compositions. Of the planets smaller than Neptune studied to date, all have radii in the near-infrared consistent with being constant in wavelength, likely showing that these small planets are consistently enshrouded in thick hazes and clouds. We explore the types of clouds and hazes that can completely obscure transmission spectra and find that very thick, lofted clouds of salts or sulfides in high metallicity (1000× solar) atmospheres create featureless transmission spectra in the near-infrared. Photochemical hazes with a range of particle sizes also create featureless transmission spectra at lower metallicities.We present a path forward for understanding this class of small planets: by understanding the thermal emission and reflectivity of small planets, we can break the degeneracies and better constrain the atmospheric compositions. Cloudy thermal emission spectra have muted features more like blackbodies, and hazy thermal emission spectra have emission features caused by an inversion layer at altitudes where the haze forms. Analysis of reflected light from warm (~400-800 K) planets can distinguish cloudy planets, which have moderate albedos (Ag=0.05–0.20), from hazy planets, which are very dark (Ag=0.0–0.03). Reflected light spectra of cold planets (~200 K) accessible to a space-based visible light coronagraph may be the key to understanding small planets: they will have high albedos and large molecular features that actually allow them to be more easily characterized than the warmer transiting planets. We suggest a number of complementary observations to characterize super Earths, including transmission spectra of hot (~1000 K) targets, thermal emission spectra of warm targets using the James Webb Space Telescope (JWST), and high spatial resolution spectral observations of directly-imaged cold targets in reflected light. These observations may provide rich diagnostics of molecules and clouds in small planets, in contrast to the limited success to date.

  11. Relativistic Iron Line Emission from the Neutron Star Low-mass X-ray Binary 4U 1636-536

    E-print Network

    Dirk Pandel; Philip Kaaret; Stephane Corbel

    2013-05-14

    We present an analysis of XMM-Newton and RXTE data from three observations of the neutron star LMXB 4U 1636-536. The X-ray spectra show clear evidence of a broad, asymmetric iron emission line extending over the energy range 4-9 keV. The line profile is consistent with relativistically broadened Fe K-alpha emission from the inner accretion disk. The Fe K-alpha line in 4U 1636-536 is considerably broader than the asymmetric iron lines recently found in other neutron star LMXBs, which indicates a high disk inclination. We find evidence that the broad iron line feature is a combination of several K-alpha lines from iron in different ionization states.

  12. Imaging Emission Spectra with Handheld and Cellphone Cameras

    ERIC Educational Resources Information Center

    Sitar, David

    2012-01-01

    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…

  13. Ion emission spectra in the Jovian X-ray aurora V. Kharchenko,1

    E-print Network

    Stancil, Phillip C.

    Ion emission spectra in the Jovian X-ray aurora V. Kharchenko,1 A. Dalgarno,1 D. R. Schultz,2 and P-ray aurora, Geophys. Res. Lett., 33, L11105, doi:10.1029/2006GL026039. 1. Introduction [2] The first detected from the Jovian North and South poles; this emission defines the Jovian X-ray aurora [Waite et al

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

    PubMed

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

    2012-06-01

    Stellar spectra are characterized by obvious absorption lines or absorption bands, while those with emission lines are usually special stars such as cataclysmic variable stars (CVs), HerbigAe/Be etc. The further study of this kind of spectra is meaningful. The present paper proposed a new method to identify emission line stars (ELS) spectra automatically. After the continuum normalization is done for the original spectral flux, line detection is made by comparing the normalized flux with the mean and standard deviation of the flux in its neighbor region The results of the experiment on massive spectra from SDSS DR8 indicate that the method can identify ELS spectra completely and accurately. Since no complex transformation and computation are involved in this method, the identifying process is fast and it is ideal for the ELS detection in large sky survey projects like LAMOST and SDSS. PMID:22870668

  15. Hydrocarbon emission features in the IR spectra of warm supergiants

    NASA Technical Reports Server (NTRS)

    Buss, R. H., Jr.; Cohen, M.; Tielens, A. G. G. M.; Werner, M. W.; Bregman, J. D.

    1990-01-01

    Observations in the 3-13 micron range are presented for two objects possessing the unidentified 21-micron feature, IRAS 22272 and IRAS 07134, which were obtained in the course of search for circumstellar aromatic hydrocarbon (PAH) emission bands. The 3.3 and 6.2 micron bands are attributed to circumstellar PAH molecules, and the 6-9 micron plateau and the 12- and 6.9-micron lines are attributed to larger, aromatic hydrocarbon clusters. These are the coolest stars known to exhibit the IR emission bands. The 21-micron feature is conjectured to also originate in a carbonaceous carrier.

  16. A vacuum ultraviolet flash lamp with extremely broadened emission spectra

    NASA Astrophysics Data System (ADS)

    Kubodera, Shoichi; Kitahara, Mitsuo; Kawanaka, Junji; Sasaki, Wataru; Kurosawa, Kou

    1996-07-01

    We have developed a vacuum ultraviolet (VUV) flash lamp using a binary rare gas mixture excited by a pulsed silent discharge. In a Kr/Xe silent discharge, the VUV emission spectral width was extended up to 26 nm full width at half-maximum (FWHM) at a center wavelength of 162 nm. According to kinetic analyses, such a spectral extension in mixed rare gases is attributed to the simultaneous emissions from heteronuclear rare gas excimers (KrXe*) and homonuclear rare gas excimers (Kr2* and Xe2*).

  17. Calculation of gain and luminescence spectra of quantum-cascade laser structures taking into account asymmetric emission line broadening

    SciTech Connect

    Ushakov, D V; Manak, I S; Kononenko, V K

    2010-05-26

    The energy levels, wave functions, and matrix elements of optical dipole transitions are calculated numerically for superlattice quantum-cascade structures. The effect of spectral broadening on the shape of emission spectra is estimated and semiphenomenological asymmetric profiles of emission line broadening are proposed. It is shown that the electroluminescence spectra well agree with the calculated spontaneous recombination spectra. (lasers)

  18. Tau-REx II: Retrieval of emission spectra

    E-print Network

    Waldmann, Ingo P; Rocchetto, Marco; Barton, Emma J; Yurchenko, Sergey N; Tennyson, Jonathan

    2015-01-01

    Tau-REx (Tau Retrieval of Exoplanets) is a novel, fully Bayesian atmospheric retrieval code custom built for extrasolar atmospheres. In Waldmann et al. (2015) the transmission spectroscopic case was introduced, here we present the emission spectroscopy spectral retrieval for the Tau-REx framework. Compared to transmission spectroscopy, the emission case is often significantly more degenerate due to the need to retrieve the full atmospheric temperature-pressure (TP) profile. This is particularly true in the case of current measurements of exoplanetary atmospheres, which are either of low signal-to-noise, low spectral resolution or both. Here we present a new way of combining two existing approaches to the modelling of the said TP profile: 1) the parametric profile, where the atmospheric TP structure is analytically approximated by a few model parameters, 2) the Layer-by-Layer approach, where individual atmospheric layers are modelled. Both these approaches have distinct advantages and disadvantages in terms of...

  19. Emission Line Spectra from Low-Density Laboratory Plasmas

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  20. Analysis of Emission Spectra of Yttrium Monoiodide Produced by the Photodissociation of YI3

    NASA Astrophysics Data System (ADS)

    Chen, Wenting Wendy; Galvin, Thomas C.; Houlahan, Thomas J., Jr.; Eden, J. Gary

    2015-06-01

    Emission spectra of yttrium monoiodide (YI) spanning the 250 - 940 nm spectral region were generated by the photodissociation of yttrium tri-iodide under photoexcitation at 248 nm (KrF laser). Fluorescent spectra in the13,000 - 19,000 cm-1 and 24,000 - 40,000 cm-1 regions will be first reported. New vibrational transitions of YI in the 20,000 - 25,000 cm-1 interval will be presented as well.

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

    SciTech Connect

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

    2011-12-31

    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.

  2. Tau-REx II: Retrieval of Emission Spectra

    NASA Astrophysics Data System (ADS)

    Waldmann, I. P.; Rocchetto, M.; Tinetti, G.; Barton, E. J.; Yurchenko, S. N.; Tennyson, J.

    2015-11-01

    {T}-REx (Tau Retrieval of Exoplanets) is a novel, fully Bayesian atmospheric retrieval code custom built for extrasolar atmospheres. In Waldmann et al., the transmission spectroscopic case was introduced, and here we present the emission spectroscopy spectral retrieval for the {T}-REx framework. Compared to transmission spectroscopy, the emission case is often significantly more degenerate due to the need to retrieve the full atmospheric temperature–pressure (TP) profile. This is particularly true in the case of current measurements of exoplanetary atmospheres, which are either of low signal-to-noise, low spectral resolution, or both. We present a new way of combining two existing approaches to the modeling of the said TP profile: (1) the parametric profile, where the atmospheric TP structure is analytically approximated by a few model parameters, (2) the layer-by-layer approach, where individual atmospheric layers are modeled. Both of these approaches have distinct advantages and disadvantages in terms of convergence properties and potential model biases. The {T}-REx hybrid model presented here is a new two-stage TP profile retrieval, which combines the robustness of the analytic solution with the accuracy of the layer-by-layer approach. The retrieval process is demonstrated using simulations of the hot-Jupiter WASP-76b and the hot-super-Earth 55 Cnc e as well as the secondary eclipse measurements of HD 189733b.

  3. Emission spectra of selected SSME elements and materials

    NASA Technical Reports Server (NTRS)

    Tejwani, Gopal D.; Vandyke, David B.; Bircher, Felix E.; Gardner, Donald G.; Chenevert, Donald J.

    1992-01-01

    Stennis Space Center (SSC) is pursuing the advancement of experimental techniques and theoretical developments in the field of plume spectroscopy for application to rocket development testing programs and engine health monitoring. Exhaust plume spectral data for the Space Shuttle Main Engine (SSME) are routinely acquired. The usefulness of this data depends upon qualitative and quantitative interpretation of spectral features and their correlation with the engine performance. A knowledge of the emission spectral characteristics of effluent materials in the exhaust plume is essential. A study of SSME critical components and their materials identified 30 elements and 53 materials whose engine exhaust plume spectral might be required. The most important were evaluated using SSC's Diagnostic Testbed Facility Thruster (DTFT), a 1200-lbf, liquid oxygen/gaseous hydrogen rocket engine which very nearly replicates the temperature and pressure conditions of the SSME exhaust plume in the first Mach diamond. This report presents the spectral data for the 10 most important elements and 27 most important materials which are strongly to moderately emitting in the DTFT exhaust plume. The covered spectral range is 300 to 426 nm and the spectral resolution is 0.25 nm. Spectral line identification information is provided and line interference effects are considered.

  4. [Instantaneous emission spectra of epoxypropane in the process of deflagration to detonation transition].

    PubMed

    Li, Ping; Yuan, Chang-ying; Hu, Dong; Liu, Jun-chao; Zhu-mei, Sun; Dong, Shi; Xiao, Hai-bo

    2004-07-01

    Using an intensified CCD spectroscopic detector (Princeton Instruments, ICCD PI-Max 1024 RB) which can be gated in as little as 5 ns, the synchronization of the measuring system was controlled by a digital delay generator (Stanford Research Systems, DG535), the DG535 was triggered externally by a lab-made electrical pulse generator which transformed the optical trigger signal to an electrical signal, and the light signal from the end window of an explosion shock tube was delivered by an 1 mm in diameter plastic optical fiber to the entrance slit of the spectrometer (grating of 150 g x mm(-1) , central wavelength of 550 nm). The spectrum measurement of the epoxypropane in the process of deflagration to detonation transition (DDT) was then made. The instantaneous emission spectra of epoxypropane at different time of the DDT process with an exposure time of several microseconds were acquired. Results show that at the beginning of the DDT process, the emitted light was very weak and the line spectra of atoms were observed mainly; in the middle process of the DDT, the emitted light became strong and the spectra observed consisted of line spectra of atoms, band spectra of molecules plus continuous spectrum of the thermal radiation; when the detonation was formed, the emitted light got very strong, and the spectra acquired consisted of both line spectra of atoms and band spectra of molecules superimposed on the strong continuum of the thermal radiation. PMID:15766070

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

    ERIC Educational Resources Information Center

    Lu, Zhe

    2012-01-01

    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…

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

    E-print Network

    Vos, Willem L.

    Quantitative analysis of directional spontaneous emission spectra from light sources in photonic disorder. Using a model comprising diffuse light transport and photonic band structure, we quantitatively of spontaneously emitted light in real photonic crystals, which is essential in the interpretation of quantum

  7. Discernment of lint trash in raw cotton using multivariate analysis of excitation-emission luminescence spectra

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Excitation-Emission luminescence spectra of basic (pH 12.5) phosphate buffer solution extracts were used to distinguish among botanical components of trash within seed cotton. All components were separated from whole plants removed from a field in southern New Mexico. Unfolded Principal Component An...

  8. FTIR Emission Spectra, Molecular Constants, and Potential Curve of Ground State GeO

    E-print Network

    Le Roy, Robert J.

    , Jenning Y. Seto, Tsuyoshi Hirao, Peter F. Bernath, and Robert J. Le Roy Guelph­Waterloo Centre allows for the presence of atomic mass-dependent Born­ Oppenheimer breakdown terms, and (ii) a "direct for Born­Oppenheimer breakdown terms. II. EXPERIMENTAL The high-resolution infrared emission spectra of Ge

  9. Valence Band X-Ray Emission Spectra of Compressed Germanium Viktor V. Struzhkin,1

    E-print Network

    Lin, Jung-Fu "Afu"

    Valence Band X-Ray Emission Spectra of Compressed Germanium Viktor V. Struzhkin,1 Ho-kwang Mao,1 the electron self-energy [3­10]. The pre- dicted band broadening is only 0.05 eV in germanium and 0.08 e

  10. Edge excitation geometry for studying intrinsic emission spectra of bulk n-InP

    E-print Network

    Luryi, Serge

    Edge excitation geometry for studying intrinsic emission spectra of bulk n-InP Oleg Semyonov, Arsen temperature a b s t r a c t The shape of the photoluminescence line excited at an edge face of InP wafer B.V. All rights reserved. 1. Introduction Luminescence spectroscopy of optically excited

  11. Application of multi-way data analysis on excitation-emission spectra for plant identification

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The ability to distinguish among diets fed to Damascus goats using excitation-emission luminescence spectra was investigated. These diets consisted of Medicago sativa L. (Alfalfa), Trifolium spp (Clover), Pistacia lentiscus (P. lentiscus), Phyllirea latifolia (P. latifolia), and Pinus brutia (P. bru...

  12. Modification of Optical Properties of Seawater Exposed to Oil Contaminants Based on Excitation-Emission Spectra

    NASA Astrophysics Data System (ADS)

    Baszanowska, E.; Otremba, Z.

    2015-10-01

    The optical behaviour of seawater exposed to a residual amount of oil pollution is presented and a comparison of the fluorescence spectra of oil dissolved in both n-hexane and seawater is discussed based on excitation-emission spectra. Crude oil extracted from the southern part of the Baltic Sea was used to characterise petroleum properties after contact with seawater. The wavelength-independent fluorescence maximum for natural seawater and seawater artificially polluted with oil were determined. Moreover, the specific excitation-emission peaks for natural seawater and polluted water were analysed to identify the natural organic matter composition. It was found that fluorescence spectra identification is a promising method to detect even an extremely low concentration of petroleum residues directly in the seawater. In addition, alien substances disturbing the fluorescence signatures of natural organic substances in a marine environment is also discussed.

  13. Iron and Nickel Line Diagnostics for the Galactic Center Diffuse Emission

    E-print Network

    Katsuji Koyama; Yoshiaki Hyodo; Tatsuya Inui; Hiroshi Nakajima; Hironori Matsumoto; Takeshi Go Tsuru; Tadayuki Takahashi; Yoshitomo Maeda; Noriko Yamazaki; Hiroshi Murakami; Shigeo Yamauchi; Yohko Tsuboi; Atsushi Senda; Jun Kataoka; Hiromitsu Takahashi; Stephen S Holt; Gregory V Brown

    2006-09-08

    We have observed the diffuse X-ray emission from the Galactic center (GC) using the X-ray Imaging Spectrometer (XIS) on Suzaku. The high-energy resolution and the low-background orbit provide excellent spectra of the GC diffuse X-rays (GCDX). The XIS found many emission lines in the GCDX near the energy of K-shell transitions of iron and nickel. The most pronounced features are FeI K alpha at 6.4 keV and K-shell absorption edge at 7.1 keV, which are from neutral and/or low ionization states of iron, and the K-shell lines at 6.7 keV and 6.9 keV from He-like (FeXXV K alpha) and hydrogenic (FeXXVI Ly alpha) ions of iron. In addition, K alpha lines from neutral or low ionization nickel (NiI K alpha) and He-like nickel (NiXXVII K alpha), and FeI K beta, FeXXV K beta, FeXXVI Ly beta, FeXXV K gamma and FeXXVI Ly gamma are detected for the first time. The line center energies and widths of FeXXV K alpha and FeXXVI Ly alpha favor a collisional excitation (CE) plasma for the origin of the GCDX. The electron temperature determined from the line flux ratio of FeXXV K alpha / FeXXV K beta is similar to the ionization temperature determined from that of FeXXV K alpha /FeXXVI Ly alpha. Thus it would appear that the GCDX plasma is close to ionization equilibrium. The 6.7 keV flux and temperature distribution to the galactic longitude is smooth and monotonic,in contrast to the integrated point source flux distribution. These facts support the hypothesis that the GCDX is truly diffuse emission rather than the integration of the outputs of a large number of unresolved point sources. In addition, our results demonstrate that the chemical composition of Fe in the interstellar gas near the GC is constrained to be about 3.5 times solar.

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

    SciTech Connect

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

    2009-06-30

    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.

  15. Thermal-neutron-capture prompt-gamma emission spectra of representative coals. [1. 5 to 11 MeV

    SciTech Connect

    Herzenberg, C L; Olson, I K

    1981-12-01

    Prompt gamma ray emission spectra have been calculated from 1.5 to 11 MeV for a wide range of coal compositions exposed to a thermal neutron flux. These include contributions to the spectra from all of the major and minor elements present in the coals. Characteristics of the spectra are discussed and correlated with the coal compositions.

  16. Rat epileptic seizures evoked by BmK {alpha}IV and its possible mechanisms involved in sodium channels

    SciTech Connect

    Chai Zhifang; Bai Zhantao; Zhang Xuying; Liu Tong; Pang Xueyan; Ji Yonghua . E-mail: yhji@server.shcnc.ac.cn

    2007-05-01

    This study showed that rat unilateral intracerebroventricular injection of BmK {alpha}IV, a sodium channel modulator derived from scorpion Buthus martensi Karsch, induced clusters of spikes, epileptic discharges and convulsion-related behavioral changes. BmK {alpha}IV potently promoted the release of endogenous glutamate from rat cerebrocortical synaptosomes. In vitro examination of the effect of BmK {alpha}IV on intrasynaptosomal free calcium concentration [Ca{sup 2+}]{sub i} and sodium concentration [Na{sup +}]{sub i} revealed that BmK {alpha}IV-evoked glutamate release from synaptosomes was associated with an increase in Ca{sup 2+} and Na{sup +} influx. Moreover, BmK {alpha}IV-mediated glutamate release and ion influx was completely blocked by tetrodotoxin, a blocker of sodium channel. Together, these results suggest that the induction of BmK {alpha}IV-evoked epileptic seizures may be involved in the modulation of BmK {alpha}IV on tetrodotoxin-sensitive sodium channels located on the nerve terminal, which subsequently enhances the Ca{sup 2+} influx to cause an increase of glutamate release. These findings may provide some insight regarding the mechanism of neuronal action of BmK {alpha}IV in the central nervous system for understanding epileptogenesis involved in sodium channels.

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

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

    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.

  18. Broad-Band Model Spectra of Gamma-Ray Emission from Millisecond Pulsars

    E-print Network

    Tomasz Bulik; Bronislaw Rudak

    1998-10-01

    We present spectra of pulsed gamma-ray emission expected from millisecond pulsars within the framework of polar-cap models. The spectra are a superposition of three components due to curvature (CR), synchrotron (SR), and Compton upscattering (ICS) processes. The CR component dominates below $100 $GeV and the ICS component exhibits a peak at $\\sim 1 $TeV. The CR component should be observable from J0437-4715 with the next generation gamma-ray telescopes, like e.g. GLAST.

  19. Laboratory simulation of infrared astrophysical features. Ph.D. Thesis; [emission spectra of comets

    NASA Technical Reports Server (NTRS)

    Rose, L. A.

    1977-01-01

    Intermediate resolution emission spectroscopy was used to study a group of 9 terrestrial silicates, 1 synthetic silicate, 6 meteorites and 2 lunar soils; comparisons were made with the intermediate resolution spectra of Comet Kohoutek in order to determine which materials best simulate the 10um astrophysical feature. Mixtures of silicates which would yield spectra matching the spectrum of the comet in the 10um region include: (1) A hydrous layer lattice silicate in combination with a high temperature condensate; (2) an amorphous magnesium silicate in combination with a high temperature condensate and (3) glassy olivine and glassy anorthite in approximately equal proportions.

  20. Peculiarities of spectra of induced emission of polymethine dye solutions at low temperatures

    NASA Technical Reports Server (NTRS)

    Melishchuk, M. V.; Tikhonov, Y. A.; Shpak, M. T.

    1981-01-01

    Results from studying the induced emission spectra with monochromatic excitation (superluminescent regime) within a temperature range of 300 K - 5.2 K are presented. The significant feature of such operations is the appearance of quasi-lines whose minimum width is realized at 4.2 K. The frequency distribution of the quasi-lines unambiguously characterizes the dye investigated. When interpreting these results, the idea of an inhomogeneous broadening of the polymethine dye spectra in the solution being studied experimentally was used for the first time. The quasi-lines observed are interpreted as a manifestation of the electron vibration structure of singlet states of a complex molecule.

  1. Method for characterization of a spherically bent crystal for K.alpha. X-ray imaging of laser plasmas using a focusing monochromator geometry

    DOEpatents

    Kugland, Nathan; Doeppner, Tilo; Glenzer, Siegfried; Constantin, Carmen; Niemann, Chris; Neumayer, Paul

    2015-04-07

    A method is provided for characterizing spectrometric properties (e.g., peak reflectivity, reflection curve width, and Bragg angle offset) of the K.alpha. emission line reflected narrowly off angle of the direct reflection of a bent crystal and in particular of a spherically bent quartz 200 crystal by analyzing the off-angle x-ray emission from a stronger emission line reflected at angles far from normal incidence. The bent quartz crystal can therefore accurately image argon K.alpha. x-rays at near-normal incidence (Bragg angle of approximately 81 degrees). The method is useful for in-situ calibration of instruments employing the crystal as a grating by first operating the crystal as a high throughput focusing monochromator on the Rowland circle at angles far from normal incidence (Bragg angle approximately 68 degrees) to make a reflection curve with the He-like x-rays such as the He-.alpha. emission line observed from a laser-excited plasma.

  2. Mid-infrared emission and Raman spectra analysis of Er(3+)-doped oxyfluorotellurite glasses.

    PubMed

    Chen, Fangze; Xu, Shaoqiong; Wei, Tao; Wang, Fengchao; Cai, Muzhi; Tian, Ying; Xu, Shiqing

    2015-04-10

    This paper reports on the spectroscopic and structural properties in Er(3+)-doped oxyfluorotellurite glasses. The compositional variation accounts for the evolutions of Raman spectra, Judd-Ofelt parameters, radiative properties, and fluorescent emission. It is found that, when maximum phonon energy changes slightly, phonon density plays a crucial role in quenching the 2.7 ?m emission generated by the Er(3+):(4)I11/2?(4)I13/2 transition. The comparative low phonon density contributes strong 2.7 ?m emission intensity. The high branching ratio (18.63%) and large emission cross section (0.95×10(-20)??cm(2)) demonstrate that oxyfluorotellurite glass contained with 50 mol.% TeO2 has potential application in the mid-infrared region laser. PMID:25967322

  3. The quantum emission spectra of rapidly-rotating Kerr black holes: Discrete or continuous?

    NASA Astrophysics Data System (ADS)

    Hod, Shahar

    2015-10-01

    Bekenstein and Mukhanov (BM) have suggested that, in a quantum theory of gravity, black holes may have discrete emission spectra. Using the time-energy uncertainty principle they have also shown that, for a (non-rotating) Schwarzschild black hole, the natural broadening ?? of the black-hole emission lines is expected to be small on the scale set by the characteristic frequency spacing ?? of the spectral lines: ?Sch ? ?? / ?? ? 1. BM have therefore concluded that the expected discrete emission lines of the quantized Schwarzschild black hole are unlikely to overlap. In this paper we calculate the characteristic dimensionless ratio ? (a bar) ? ?? / ?? for the predicted BM emission spectra of rapidly-rotating Kerr black holes (here a bar ? J /M2 is the dimensionless angular momentum of the black hole). It is shown that ? (a bar) is an increasing function of the black-hole angular momentum. In particular, we find that the quantum emission lines of Kerr black holes in the regime a bar ? 0.9 are characterized by the dimensionless ratio ? (a bar) ? 1 and are therefore effectively blended together. Our results thus suggest that, even if the underlying mass (energy) spectrum of these rapidly-rotating Kerr black holes is fundamentally discrete as suggested by Bekenstein and Mukhanov, the natural broadening phenomenon (associated with the time-energy uncertainty principle) is expected to smear the black-hole radiation spectrum into a continuum.

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

    SciTech Connect

    Ewing, Ian; Christian, Damian J.; Bodewits, Dennis; Dennerl, Konrad; Lisse, Carey M.; Wolk, Scott J. E-mail: daman.christian@csun.edu

    2013-01-20

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

  5. High-resolution emission spectra of pulsed terahertz quantum-cascade lasers

    SciTech Connect

    Ikonnikov, A. V. Antonov, A. V.; Lastovkin, A. A.; Gavrilenko, V. I.; Sadof'ev, Yu. G.; Samal, N.

    2010-11-15

    The spectra of pulsed terahertz quantum-cascade lasers were measured with high spectral resolution. The characteristic line width at half maximum was 0.01 cm{sup -1}; it is controlled by laser temperature variations during the supply voltage pulse. It was shown that an increase in the laser temperature leads to a decrease in the emission frequency, which is caused by an increase in the effective refractive index of the active region. It was also found that a decrease in the supply voltage results in a decrease in the emission frequency, which is caused by a change in the energy of diagonal transitions between lasing levels.

  6. Influence of the projectile charge state on electron emission spectra from a Cu(111) surface

    NASA Astrophysics Data System (ADS)

    Archubi, C. D.; Silkin, V. M.; Gravielle, M. S.

    2015-09-01

    Double differential electron emission distributions produced by grazing impact of fast dressed ions on a Cu(111) surface are investigated focusing on the effects of the electronic band structure. The process is described within the Band-Structure-Based approximation, which is a perturbative method that includes an accurate representation of the electron-surface interaction, incorporating information of the electronic band structure of the solid. Differences in the behavior of the emission spectra for He+ q, Li+ q, Be+ q and C+ q projectiles with different charge states q are explained by the combined effect of the projectile trajectory and the projectile charge distribution.

  7. Measurements of trace constituents from atmospheric infrared emission and absorption spectra, a feasibility study

    NASA Technical Reports Server (NTRS)

    Goldman, A.; Williams, W. J.; Murcray, D. G.

    1974-01-01

    The feasibility of detecting eight trace constituents (CH4, HCl, HF, HNO3, NH3, NO, NO2 and SO2) against the rest of the atmospheric background at various altitudes from infrared emission and absorption atmospheric spectra was studied. Line-by-line calculations and observational data were used to establish features that can be observed in the atmospheric spectrum due to each trace constituent. Model calculations were made for experimental conditions which approximately represent state of the art emission and absorption spectrometers.

  8. Robust red-emission spectra and yields in firefly bioluminescence against temperature changes

    NASA Astrophysics Data System (ADS)

    Mochizuki, Toshimitsu; Wang, Yu; Hiyama, Miyabi; Akiyama, Hidefumi

    2014-05-01

    We measured the quantitative spectra of firefly (Photinus pyralis) bioluminescence at various temperatures to investigate the temperature dependence of the luciferin-luciferase reaction at 15-34 °C. The quantitative spectra were decomposed very well into red (1.9 eV), orange (2.0 eV), and green (2.2 eV) Gaussian components. The intensity of the green component was the only temperature sensitive quantity that linearly decreased as the temperature increased at pH 7 and 8. We found the quantitative bioluminescence spectra to be robust below 2.0 eV against temperature and other experimental conditions. The revealed robustness of the red emissions should be useful for quantitative applications such as adenosine-5'-triphosphate detection.

  9. Study of dynamic emission spectra from lubricant films in an elastohydrodynamic contact using Fourier transform spectroscopy

    NASA Technical Reports Server (NTRS)

    Lauer, J. L.

    1978-01-01

    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 temperatures were used. Most of the spectra exhibited polarization characteristics, indicating directional alignment of the lubricant in the EHD contact. Among the fluids studied were a "traction" fluid, an advanced ester, and their mixtures, a synthetic paraffin, a naphthenic reference fluid (N-1), both neat and containing 1 percent of p-tricresyl phosphate as an anti-wear additive, and a C-ether. Traction properties were found to be nearly proportional to mixture composition for traction fluid and ester mixtures. The anti-wear additive reduced traction and fluid temperature under low loads but increased them under higher loads, giving rise to formation of a friction polymer.

  10. Control of emission spectra in quantum dot microdisk/microring lasers.

    PubMed

    Kryzhanovskaya, N V; Mukhin, I S; Moiseev, E I; Shostak, I I; Bogdanov, A A; Nadtochiy, A M; Maximov, M V; Zhukov, A E; Kulagina, M M; Vashanova, K A; Zadiranov, Yu M; Troshkov, S I; Lipovskii, A A; Mintairov, A

    2014-10-20

    Focused ion beam is applied to quantum dot based microresonators to form pits or groove on their surface. The emission spectra of the resonators based lasers are significantly thinned out after the ion beam milling, and one or two modes become dominant instead of a group of modes having comparable intensities. The linewidth of the lasing mode is kept unchanged, whereas the lasing threshold demonstrates an insignificant growth. PMID:25401612

  11. Near infrared emission spectra of CoH and CoD Iouli E. Gordon a

    E-print Network

    Le Roy, Robert J.

    Near infrared emission spectra of CoH and CoD Iouli E. Gordon a , Robert J. Le Roy b , Peter FH and CoD molecules have been recorded in the 640 nm to 3.5 lm region using a Fourier transform U4 electronic transition of CoD, and five bands for the corresponding transition of CoH. The (0

  12. Triplet emission from poly(3,6-dibromo-N-vinylcarbazole): Spectra and kinetics

    SciTech Connect

    Starzyk, F.; Burkhart, R.D. )

    1989-01-01

    The triplet delayed emission of poly(3,6-dibromo-N-vinylcarbazole) (PdBVK) in a 2-methyltetrahydrofuran (MTHF) frozen solution at 77K was examined within the spectral and time regimes of 400-570 nm and 0.2-50 ms, respectively. The influence on optical absorption of bromine substitution into the carbazole ring (3- and 6-positions) of poly(N-vinylcarbazole), as well as delayed triplet emission spectra and the kinetic decays, was monitored. The phosphorescence spectra were recorded at different delay times after excitation. The phosphorescence decays were found to be essentially exponential in the wings of the phosphorescence band but showed unusual, definitely nonexponential, behavior in the range 460-475 nm, which is the range of maximum phosphorescence intensity. A resolution of the phosphorescence band into Gaussian components yielded excellent fits by using three components at delay times less than 2 ms and two components for spectra taken at longer delay times. Based upon an average of 12 different spectra recorded at various times after excitation, the calculated wavelengths at maximum intensity for these Gaussian components were found to be 448{plus minus}2 nm, 473{plus minus}4 nm, and 501{plus minus}8 nm.

  13. EVIDENCE FOR SECONDARY EMISSION AS THE ORIGIN OF HARD SPECTRA IN TeV BLAZARS

    SciTech Connect

    Zheng, Y. G.; Kang, T.

    2013-02-20

    We develop a model for the possible origin of hard, very high energy (VHE) spectra from a distant blazar. In the model, both the primary photons produced in the source and secondary photons produced outside it contribute to the observed high-energy {gamma}-ray emission. That is, the primary photons are produced through the synchrotron self-Compton process, and the secondary photons are produced through high-energy proton interactions with background photons along the line of sight. We apply the model to a characteristic case of VHE {gamma}-ray emission in the distant blazar 1ES 1101-232. Assuming suitable electron and proton spectra, we obtain excellent fits to the observed spectra of this blazar. This indicated that the surprisingly low attenuation of the high-energy {gamma}-rays, especially the shape of the VHE {gamma}-ray tail of the observed spectra, can be explained by secondary {gamma}-rays produced in interactions of cosmic-ray protons with background photons in intergalactic space.

  14. Sources of High-Energy Emission in the Green Pea Galaxies: New Constraints from Magellan Spectra

    NASA Astrophysics Data System (ADS)

    Carroll, Derek Alexander

    2016-01-01

    The recently discovered Green Pea galaxies display extreme starburst activity and may be some of the only possible Lyman continuum emitting galaxies at low redshift. Green Peas are characterized by their unusually high [O III]/[O II] ratios, similar to the ratios observed in high-redshift galaxies. In addition, the presence of the high-energy He II 4686 line shows that the Green Peas are highly ionized. However, the origin of the He II emission in the Green Peas, and many other starburst galaxies, is still an open question. We analyze IMACS and MagE spectra from the Magellan telescopes in order to evaluate the most probable cause of this He II emission. We also analyze other properties like dust content, temperature and density, and kinematic components. Our IMACS spectra show no Wolf-Rayet (WR) features. We set upper limits on the WR populations in our sample and conclude that Wolf-Rayet stars are not a likely candidate for the He II emission. With deeper MagE spectra we investigate energetic shocks as a possible source of the He II, and move one step closer to uncovering the origin of high-energy photons in these unique starbursts.

  15. Relativistic configuration-interaction calculation of $K\\alpha$ transition energies in beryllium-like iron

    E-print Network

    Yerokhin, V A; Fritzsche, S

    2014-01-01

    We perform relativistic configuration-interaction calculations of the energy levels of the low-lying and core-excited states of beryllium-like iron, Fe$^{22+}$. The results include the QED contributions calculated by two different methods, the model QED operator approach and the screening-potential approach. The uncertainties of theoretical energies are estimated systematically. The predicted wavelengths of the K\\alpha transitions in beryllium-like iron improve previous theoretical results and compare favorably with the experimental data.

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

    PubMed

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

    2015-06-01

    We use the TDDFT/PBE0/6-31+G* method to determine the electronic absorption and emission energies, in different media, of the four forms of tocopherol, which differ by the number and the position of methyl groups on the chromanol. Geometries of the ground state S0 and the first singlet excited state S1 were optimized in the gas phase, and various solvents. The solvent effect is evaluated using an implicit solvation model (IEF-PCM). Our results are compared to the experimental ones obtained for the vitamin E content in several vegetable oils. For all forms of tocopherols, the HOMO-LUMO first vertical excitation is a ?-?* transition. Gas phase and non-polar solvents (benzene and toluene) give higher absorption wavelengths than polar solvents (acetone, ethanol, methanol, DMSO, and water); this can be interpreted by a coplanarity between the O-H group and the chroman, allowing a better electronic resonance of the oxygen lone pairs and the aromatic ring, and therefore giving an important absorption wavelength, whereas the polar solvents give high emission wavelengths comparatively to gas phase and non-polar solvents. Fluorescence spectra permit the determination, the separation, and the identification of the four forms of tocopherols by a large difference in emission wavelength values. Graphical Abstract Scheme from process methodological to obtain the absorption and emission spectra for tocopherols. PMID:26026299

  17. Excitation-emission spectra and fluorescence quantum yields for fresh and aged biogenic secondary organic aerosols

    SciTech Connect

    Lee, Hyun Ji; Laskin, Alexander; Laskin, Julia; Nizkorodov, Sergey A.

    2013-05-10

    Certain biogenic secondary organic aerosols (SOA) become absorbent and fluorescent when exposed to reduced nitrogen compounds such as ammonia, amines and their salts. Fluorescent SOA may potentially be mistaken for biological particles by detection methods relying on fluorescence. This work quantifies the spectral distribution and effective quantum yields of fluorescence of SOA generated from two monoterpenes, limonene and a-pinene, and two different oxidants, ozone (O3) and hydroxyl radical (OH). The SOA was generated in a smog chamber, collected on substrates, and aged by exposure to ~100 ppb ammonia vapor in air saturated with water vapor. Absorption and excitation-emission matrix (EEM) spectra of aqueous extracts of aged and control SOA samples were measured, and the effective absorption coefficients and fluorescence quantum yields (~0.005 for 349 nm excitation) were determined from the data. The strongest fluorescence for the limonene-derived SOA was observed for excitation = 420+- 50 nm and emission = 475 +- 38 nm. The window of the strongest fluorescence shifted to excitation = 320 +- 25 nm and emission = 425 +- 38 nm for the a-pinene-derived SOA. Both regions overlap with the excitation-emission matrix (EEM) spectra of some of the fluorophores found in primary biological aerosols. Our study suggests that, despite the low quantum yield, the aged SOA particles should have sufficient fluorescence intensities to interfere with the fluorescence detection of common bioaerosols.

  18. Reinvestigation of the Emission Spectra Following the 266 NM Photolysis of Iodomethanes

    NASA Astrophysics Data System (ADS)

    Tu, Cian-Ping; Cheng, Hsin-I.; Chang, Bor-Chen

    2013-06-01

    Nascent emission spectra following the 266 nm photolysis of iodomethanes (CHI_3, CH_2I_2, CH_3I, and CH_2ICl) were recorded in a slow flow system, and are similar to those following the 266 nm photolysis of bromomethanes except a number of unknown bands that appear between 520 nm and 820 nm. Interestingly, there are no isotopic shifts in these unknown bands even when the precursors were replaced by the deuterated or ^{13}C-substituted isotopomers (CD_2I_2, CD_3I, and ^{13}CH_2I_2). This indicates that the carrier of these unknown bands does not contain any hydrogen or carbon atoms. Laser-induced fluorescence (LIF) excitation and dispersed-fluorescence (DF) spectra were recorded, but these spectra show different vibrational structures than those of the unknown bands. While the LIF and DF spectra can be well described by the I_2 b^3 ? _{0,u} ^+ - X^1 ? _g ^+ transition, there exist systematic deviations between the unknown bands and the I_2 b-X transition. We have improved the signal-to-noise (S/N) ratios and the resolution for these unknown bands. Our new analysis shows that the unknown bands consist of several band systems including the I_2 b-X transition. Moreover, the excited state iodine atom was found in the nascent emission spectra, but its formation mechanism still remains unsolved. The details of our current progress will be presented. S.-X. Yang, G.-Y. Hou, J.-H. Dai, C-.H. Chang, and B.-C. Chang, J. Phys. Chem. A 114, 4785 (2010). J.-J. Du, C.-H. Chen, and B.-C. Chang, 67^{th} OSU International Symposium on Molecular Spectroscopy, WG04 (2012).

  19. Temperature measurements in microwave argon plasma source by using overlapped molecular emission spectra

    NASA Astrophysics Data System (ADS)

    Abdel-Fattah, E.; Bazavan, M.; Shindo, H.

    2015-09-01

    The electron excitation temperature Texc, vibrational Tvib, and rotational Trot temperatures were measured in a high-pressure line-shaped microwave plasma source in argon over a wide range of gas pressure and microwave power, by using optical emission spectra. The selected ArI transition lines 5p-4s and 4p-4s were chosen to calculate electron excitation temperature using Boltzmann's plot method. Meanwhile, the emission spectra of hydroxyl OH molecular ( A 2 ? + - X 2 ? i , ? ? = 0 ) band and the nitrogen N2 second positive system ( C 3 ? u - B 3 ? g , ? ? = + 1 ), both second diffraction order, were used to evaluate the vibrational Tvib and rotational Trot temperatures using the method of comparing the measured and calculated spectra with a chi-squared minimization procedure. The components of the overlapped spectrum are greatly influenced by the gas pressure; however, they are independent on microwave power. For temperatures, it was found that the Texc dramatically decreases from 2.5 to 0.75 eV, which qualitatively agrees with T e deduced from zero-global model. Both of Tvib and Trot significantly decrease with as gas pressure increase from 0.4 to 50 Torr. Yet, they behave differently with microwave power.

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

    SciTech Connect

    Jaenes, Juergen; Laur, Sven; Kolka, Indrek

    2008-12-05

    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.

  1. Method of fission product beta spectra measurements for predicting reactor anti-neutrino emission

    SciTech Connect

    Asner, David M.; Burns, Kimberly A.; Campbell, Luke W.; Greenfield, Bryce A.; Kos, Marek S.; Orrell, John L.; Schram, Malachi; VanDevender, Brent A.; Wood, Lynn S.; Wootan, David W.

    2015-03-01

    The nuclear fission process that occurs in the core of nuclear reactors results in unstable, neutron-rich fission products that subsequently beta decay and emit electron antineutrinos. These reactor neutrinos have served neutrino physics research from the initial discovery of the neutrino to today's precision measurements of neutrino mixing angles. The prediction of the absolute flux and energy spectrum of the emitted reactor neutrinos hinges upon a series of seminal papers based on measurements performed in the 1970s and 1980s. The steadily improving reactor neutrino measurement techniques and recent reconsiderations of the agreement between the predicted and observed reactor neutrino flux motivates revisiting the underlying beta spectra measurements. A method is proposed to use an accelerator proton beam delivered to an engineered target to yield a neutron field tailored to reproduce the neutron energy spectrum present in the core of an operating nuclear reactor. Foils of the primary reactor fissionable isotopes placed in this tailored neutron flux will ultimately emit beta particles from the resultant fission products. Measurement of these beta particles in a time projection chamber with a perpendicular magnetic field provides a distinctive set of systematic considerations for comparison to the original seminal beta spectra measurements. Ancillary measurements such as gamma-ray emission and post-irradiation radiochemical analysis will further constrain the absolute normalization of beta emissions per fission. The requirements for unfolding the beta spectra measured with this method into a predicted reactor neutrino spectrum are explored.

  2. Effects of Space Weathering on Thermal Infrared Emissivity Spectra of Bulk Lunar Soils Measured Under Simulated Lunar Conditions

    NASA Astrophysics Data System (ADS)

    Donaldson Hanna, K. L.; Bowles, N. E.; Pieters, C. M.; Greenhagen, B. T.; Glotch, T. D.; Lucey, P. G.

    2015-11-01

    In this initial study, TIR emissivity spectral measurements are made under lunar-like conditions of two highland soil samples that are similar in composition, but differing maturities to understand the effects of space weathering on TIR spectra.

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

    SciTech Connect

    Gerhardt, Ilja; Sin, Kyungseob; Momose, Takamasa

    2012-07-07

    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.

  4. TIR Emissivity Spectra of Thermally Processed Sulfates, Carbonates and Phyllosilicates as Analog Materials for Asteroid Surfaces

    NASA Astrophysics Data System (ADS)

    Maturilli, A.; Helbert, J.; D'Amore, M.; Ferrari, S.

    2013-12-01

    At the Planetary Emissivity Laboratory (PEL) of the German Aerospace Center (DLR) in Berlin we are building a database of spectral measurements of several meteorites and other analogs for asteroid surfaces. Bi-directional reflectance of samples in the 1 to 100 ?m spectral range, are measured by using an evacuated (10-4 bar) Bruker Vertex 80V FTIR spectrometer and a Bruker A513 reflection unit, allowing phase angles between 26° and 170°. Emissivity in the 1 to 100 ?m spectral range is measured with the same instrument coupled with an external emissivity chamber, for sample temperatures ranging from low (50° C) to very high (above 800° C). We present here new measurements on sulfates, carbonates, and phyllosilicates in various grain size ranges. The setup was configured to simulate the thermal history of surface minerals on the asteroid 2008 EV5 during its revolution around the Sun. This asteroid is the scientific target of the ESA Marco Polo-R mission. The samples in vacuum (< 0.8 mbar) are measured at surface temperature around 70° C, then the same samples are heated to 220° C, and maintained at this temperature for one hour. Slowly the sample temperature is reduced back again to 70° C and a second measurement is taken. Emissivity spectra before and after thermal processing of the samples are complemented with reflectance measurements on samples fresh and after thermal processing. This comparison show us that for some minerals no spectral/structural changes appear, while others show signs of dehydration and among them some species show structural changes. We conclude that a proper spectral library of emissivity spectra for asteroid analogue materials must include thermally processed samples, reproducing the thermal evolution for the asteroid that is target of the actual investigation.

  5. Emission spectra of the cations of some fluoro-substituted phenols in the gaseous phase

    USGS Publications Warehouse

    Maier, John Paul; Marthaler, O.; Mohraz, Manijeh; Shiley, R.H.

    1980-01-01

    Emission spectra of the cations of 2,5- and 3,5-difluorophenol, of 2,3,4- and 2,4,5-trifluorophenol, of 2,3,5,6-tetrafluorophenol and of 2,3,4,5,6-pentafluorophenol have been obtained in the gas phase using low-energy electron beam excitation. The band systems are assigned to the B??(??-1) ??? X??(??-1) electronic transitions of these cations by reference to photoelectron spectroscopic data. The He(I??) photoelectron spectra and the ionisation energies of ten fluoro-substituted phenols are reported. The symmetries of the four lowest electronic states of these cations are inferred from the radiative decay studies. The lifetimes of the lowest vibrational levels of the B??(??-1) state of the six fluoro-substituted phenol cations above have also been measured. ?? 1980.

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

    SciTech Connect

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

    2012-07-15

    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.

  7. An algorithm for identification of substances using a finite set of secondary-emission spectra

    NASA Astrophysics Data System (ADS)

    Vasil'ev, N. S.; Golyak, Il. S.; Morozov, A. N.

    2015-01-01

    A problem of identification of chemical composition in the absence of sampling procedures is considered. A method that allows identification using spectra of a desired substance is proposed. The measure of the difference between spectral sets is determined. The method is employed in the experiments using a visible and near-UV Fourier spectrometer. The secondary emission of samples is excited by UV sources with maximum intensities at wavelengths of 280 and 310 nm. Anthracene, POPOP, PPO, stilbene, and tryptophan are used in experiments. The ROC curves are constructed and compared to specify the parameters that are used in the algorithm for searching for substances in the database of reference spectra. The results will make it possible to improve the reliability and applicability of express analyzers of chemical substances.

  8. Non-detection of X-ray emission from sterile neutrinos in stacked galaxy spectra

    NASA Astrophysics Data System (ADS)

    Anderson, Michael E.; Churazov, Eugene; Bregman, Joel N.

    2015-10-01

    We conduct a comprehensive search for X-ray emission lines from sterile neutrino dark matter, motivated by recent claims of unidentified emission lines in the stacked X-ray spectra of galaxy clusters and the centres of the Milky Way and M31. Since the claimed emission lines lie around 3.5 keV, we focus on galaxies and galaxy groups (masking the central regions), since these objects emit very little radiation above ˜2 keV and offer a clean background against which to detect emission lines. We develop a formalism for maximizing the signal-to-noise of decaying dark matter emission lines by weighing each X-ray event according to the expected dark matter profile. In total, we examine 81 and 89 galaxies with Chandra and XMM-Newton, respectively, totalling 15.0 and 14.6 Ms of integration time. We find no significant evidence of any emission lines, placing strong constraints on the mixing angle of sterile neutrinos with masses between 4.8 and 12.4 keV. In particular, if the 3.57 keV feature from Bulbul et al. were due to 7.1 keV sterile neutrino emission, we would have detected it at 4.4? and 11.8? in our two samples. The most conservative estimates of the systematic uncertainties reduce these constraints to 4.4? and 7.8?, or letting the line energy vary between 3.50 and 3.60 keV reduces these constraints to 2.7? and 11.0?, respectively. Unlike previous constraints, our measurements do not depend on the model of the X-ray background or on the assumed logarithmic slope of the centre of the dark matter profile.

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

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

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

  10. INK: A computer program for accurate analysis of particle-induced X-ray emission spectra

    NASA Astrophysics Data System (ADS)

    Jabr, I. J.; Saleh, N. S.; Hallak, A. B.

    A computer program, INK, for the analysis of spectra obtained in proton induced X-ray emission (PIXE) is described. It fits Gaussian-shaped lines to the characteristic peaks. The continuum is fitted by an exponential function representing bremsstrahlung of the incident particles, secondary electron induced bremsstrahlung and different Compton scattering processes. The program is largely automatic. It is capable of providing fits for up to 20 elements in one to four minutes on a small microcomputer. It locates all peaks in a read-in spectrum and determines their energies, areas and elemental abundances. Applications to biological and geological samples are discussed.

  11. Evolution of the L satellites in the X-ray emission spectra of ? region

    NASA Astrophysics Data System (ADS)

    Poonia, Surendra

    2005-05-01

    The X-ray satellites L?1^I, L?1^II, L?1^III, L?1^IV, L?2^I, L?2^(b), L?2^II and L?2^(c) observed in the L-emission spectra in elements with Z = 26 to 92, have been calculated. The energies of various transitions have been calculated by available Hartree-Fock-Slater (HFS) data using the semi-empirical Auger transition energies in the doubly ionized atoms and their relative intensities have been estimated by considering cross - sections of singly ionized 2x-1 (x ? s, p) states and then of subsequent Coster-Kronig and shake off processes. The calculated spectra have been compared with the measured satellite energies in the L emission spectra. Their intense peaks have been identified as the observed satellite lines. The one to one correspondence between the peaks in calculated spectra and the satellites in measured spectra has been established on the basis of the agreement between the separations in the peak energies and those in the measured satellite energies. Group of transitions under the transition schemes L2Mx-MxM4,5 andL3Mx-MxN4,5 (x ? 1-5), which give, rise to these satellites have been identified. It is observed that the satellite L?2^(b) in all these spectra can be assigned to the superposition of ^3F4-^3G5 and ^3F4-^3D3 transitions and that this must be most intense one out of all these satellites, contributing in order of decreasing intensity. Each of the remaining satellites is found to have different origin in different elements. The possible contributions of the suitable transitions to all these lines have also been discussed. References:1. Y. Cauchois and C. Senemaud, X-Ray Wavelength Tables, 2^nd ed., (Oxford: Pergamon) pp. 217-314, (1978).2. S.N.Soni, J. Phys. B: At. Mol. Opt. Phys. 23, 1117-1128, (1990).3. S. N. Soni and M. H. Massoud, J. Phys. Chem. Solids 58(1), 145-151 (1997).4. S. N. Soni and S. Poonia, J. Phys. Chem. Solids 61(9), 1509-1518 (2000).5. S. Poonia and S. N. Soni, J. Phys. Chem. Solids 62(3), 503-511 (2001).

  12. The history of the iron K-alpha line profile in the Piccinotti AGN ESO198-G24

    E-print Network

    M. Guainazzi

    2003-02-06

    This paper presents ASCA (July 1997), XMM-Newton (December 2000) and BeppoSAX (January 2001) observations of the Piccinotti Seyfert 1 galaxy ESO198-G24. The BeppoSAX 0.1-200 keV spectrum exhibits reprocessing features, probably produced by an X-ray illuminated, relativistic accretion disk subtending a solid angle \\~2 pi. During the XMM-Newton observation the fluorescent iron K-alpha line profile (centroid energy E~6.4 keV) was broad and twice as bright as in the BeppoSAX observation. An additional emission feature (E~5.7 keV), detected at the 96.3% confidence level, may be part of a relativistic, double-peaked profile. By contrast, in the earlier ASCA observation the line profile is dominated by a remarkably narrow "core" (intrinsic width <50 eV). If this component is produced by reflection off the inner surface of a molecular torus, its large Equivalent Width (~300 eV) most likely represents the "echo" of a previously brighter flux state, in agreement with the dynamical range covered by the historical X-ray light curve in ESO198-G24.

  13. Discovery of the Red-Skewed K-alpha Iron Line in Cyg X-2 with Suzaku

    NASA Technical Reports Server (NTRS)

    Shaposhnikov, Nikolai; Titarchuk, Lev; Laurent, Philippe

    2008-01-01

    We report on the Suzaku observation of neutron star low-mass X-ray binary Cygnus X-2 which reveals strong iron K-alpha emission line. The line profile shows a prominent red wing extending down to 4 keV. This discovery increases the number of neutron star sources where red-skewed iron lines were observed and strongly suggests that this phenomenon is common not only in black holes but also in other types of compact objects. We examine the line profile by fitting it with the model which attributes its production to the relativistic effects due to disk reflection of X-ray radiation. We also apply an alternative model where the red wing is a result of down-scattering effect of the first order with respect to electron velocity in the wind outflow. Both models describe adequately the observed line profile. However, the X-ray variability in a state similar to that in the Suzaku observation which we establish by analysing RXTE observation favors the wind origin of the line formation.

  14. Gamma-ray burst prompt emission light curves and power density spectra in the ICMART model

    SciTech Connect

    Zhang, Bo; Zhang, Bing E-mail: zhang@physics.unlv.edu

    2014-02-20

    In this paper, we simulate the prompt emission light curves of gamma-ray bursts (GRBs) within the framework of the Internal-Collision-induced MAgnetic Reconnection and Turbulence (ICMART) model. This model applies to GRBs with a moderately high magnetization parameter ? in the emission region. We show that this model can produce highly variable light curves with both fast and slow components. The rapid variability is caused by many locally Doppler-boosted mini-emitters due to turbulent magnetic reconnection in a moderately high ? flow. The runaway growth and subsequent depletion of these mini-emitters as a function of time define a broad slow component for each ICMART event. A GRB light curve is usually composed of multiple ICMART events that are fundamentally driven by the erratic GRB central engine activity. Allowing variations of the model parameters, one is able to reproduce a variety of light curves and the power density spectra as observed.

  15. K{beta} resonant x-ray emission spectra in MnF{sub 2}

    SciTech Connect

    Taguchi, M.; Parlebas, J. C.; Uozumi, T.; Kotani, A.; Kao, C.-C.

    2000-01-15

    We report experimental and theoretical results on Mn K{beta} resonant x-ray emission spectra (K{beta} RXES) at the pre-edge region of K-edge x-ray absorption spectroscopy in a powdered MnF{sub 2} sample. The experimental results are studied theoretically in terms of coherent second-order optical process, using a MnF{sub 6}{sup -4} cluster model with the effects of intra-atomic multiplet coupling and interatomic hybridization in the space of three configurations and taking into account both the Mn 1s-3d quadrupole excitation and the Mn 1s-4p dipole excitation. The agreement between theory and experiment is good. Moreover, we show that if the sample is a single crystal the resonant x-ray emission spectroscopy caused by the quadrupole excitation has a strong sensitivity to the angle of the incident photon. (c) 2000 The American Physical Society.

  16. Vibration-rotation emission spectra of gaseous ZnH2 and ZnD2.

    PubMed

    Shayesteh, Alireza; Appadoo, Dominique R T; Gordon, Iouli E; Bernath, Peter F

    2004-11-10

    Gaseous ZnH2 and ZnD2 have been discovered in an emission source that combines an electrical discharge with a high-temperature furnace. High-resolution infrared emission spectra of ZnH2 and ZnD2 have been recorded with a Fourier transform spectrometer, and the antisymmetric stretching fundamental bands of 64ZnH2 and 64ZnD2 were detected near 1889.4 and 1371.6 cm-1, respectively. Rotational analysis of the bands yielded r0 bond distances of 1.535 271(1) and 1.531 836(9) A for linear 64ZnH2 and 64ZnD2, respectively. PMID:15521746

  17. Time evolution, Lamb shift, and emission spectra of spontaneous emission of two identical atoms

    SciTech Connect

    Wang Dawei; Li Zhenghong; Zheng Hang; Zhu Shiyao

    2010-04-15

    A unitary transformation method is used to investigate the dynamic evolution of two multilevel atoms, in the basis of symmetric and antisymmetric states, with one atom being initially prepared in the first excited state and the other in the ground state. The unitary transformation guarantees that our calculations are based on the ground state of the atom-field system and the self-energy is subtracted at the beginning. The total Lamb shifts of the symmetric and antisymmetric states are divided into transformed shift and dynamic shift. The transformed shift is due to emitting and reabsorbing of virtual photons, by a single atom (nondynamic single atomic shift) and between the two atoms (quasi-static shift). The dynamic shift is due to the emitting and reabsorbing of real photons, by a single atom (dynamic single atomic shift) and between the two atoms (dynamic interatomic shift). The emitting and reabsorbing of virtual and real photons between the two atoms result in the interatomic shift, which does not exist for the one-atom case. The spectra at the long-time limit are calculated. If the distance between the two atoms is shorter than or comparable to the wavelength, the strong coupling between the two atoms splits the spectrum into two peaks, one from the symmetric state and the other from the antisymmetric state. The origin of the red or blue shifts for the symmetric and antisymmetric states mainly lies in the negative or positive interaction energy between the two atoms. In the investigation of the short time evolution, we find the modification of the effective density of states by the interaction between two atoms can modulate the quantum Zeno and quantum anti-Zeno effects in the decays of the symmetric and antisymmetric states.

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

    SciTech Connect

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

    2011-09-06

    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.

  19. Fourier transform infrared emission spectra of MgH and MgD A. Shayesteh and D. R. T. Appadoo

    E-print Network

    Le Roy, Robert J.

    Fourier transform infrared emission spectra of MgH and MgD A. Shayesteh and D. R. T. Appadoo, Ontario, N2L 3G1, Canada Received 9 February 2004; accepted 8 March 2004 High resolution Fourier transform the emission spectrum of the A 2 X 2 transition of MgH using a magnesium hollow cathode discharge and a Fourier

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

    SciTech Connect

    Ma, Jian; Cao, Jianshu

    2015-03-07

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

  1. ``Drifting tadpoles'' in wavelet spectra of decimetric radio emission of fiber bursts

    NASA Astrophysics Data System (ADS)

    Mészárosová, H.; Karlický, M.; Rybák, J.; Ji?i?ka, K.

    2009-08-01

    Aims: The solar decimetric radio emission of fiber bursts was investigated searching for the “drifting tadpole” structures proposed by theoretical studies. Methods: Characteristic periods with the tadpole pattern were searched for in the radio flux time series by wavelet analysis methods. Results: For the first time, we have found drifting tadpoles in the wavelet spectra of the decimetric radio emission associated with the fiber bursts observed in July 11, 2005. These tadpoles were detected at all radio frequencies in the 1602-1780 MHz frequency range. The characteristic period of the wavelet tadpole patterns was found to be 81.4 s and the frequency drift of the tadpole heads is -6.8 MHz s-1. These tadpoles are interpreted as a signature of the magnetoacoustic wave train moving along a dense flare waveguide and their frequency drift as a motion of the wave train modulating the radio emission produced by the plasma emission mechanism. Using the Aschwanden density model of the solar atmosphere, only low values of the Alfvén speed and the magnetic field strength in the loop guiding this wave train were derived which indicates a neutral current sheet as the guiding structure. The present analysis supports the model of fiber bursts based on whistler waves.

  2. Determination of thermal emission spectra maximizing thermophotovoltaic performance using a genetic algorithm

    E-print Network

    DeSutter, John; Francoeur, Mathieu

    2015-01-01

    Optimal radiator thermal emission spectra maximizing thermophotovoltaic (TPV) conversion efficiency and output power density are determined when temperature effects in the cell are considered. To do this, a framework is designed in which a TPV model that accounts for radiative, electrical and thermal losses is coupled with a genetic algorithm. The TPV device under study involves a spectrally selective radiator at a temperature of 2000 K, a gallium antimonide cell, and a cell thermal management system characterized by a fluid temperature and a heat transfer coefficient of 293 K and 600 Wm-2K-1. It is shown that a maximum conversion efficiency of 38.8% is achievable with an emission spectrum that has emissivity of unity between 0.719 eV and 0.763 eV and zero elsewhere. This optimal spectrum is less than half of the width of those when thermal losses are neglected. A maximum output power density of 41708 Wm-2 is achievable with a spectrum having emissivity values of unity between 0.684 eV and 1.082 eV and zero e...

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

    PubMed Central

    2012-01-01

    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. PMID:22809100

  4. Detection of H2 Emission from Mira B in UV Spectra from the Hubble Space Telescope

    E-print Network

    Brian E. Wood; Margarita Karovska; Warren Hack

    2001-07-02

    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 lines fluoresced by H I Ly-alpha, which were not detected in any of the numerous observations of Mira B by the International Ultraviolet Explorer (IUE). The high temperature lines detected by IUE (e.g., C IV 1550) still exist in the STIS spectrum but with dramatically lower fluxes. The continuum fluxes in the STIS spectra are also much lower, being more than an order of magnitude lower than ever observed by IUE, and also an order of magnitude lower than fluxes observed in more recent HST Faint Object Camera objective prism spectra from 1995. Thus, the accretion rate onto Mira B was apparently much lower when STIS observed the star, and this change altered the character of Mira B's UV spectrum.

  5. Measuring nickel masses in Type Ia supernovae using cobalt emission in nebular phase spectra

    E-print Network

    Childress, Michael J; Seitenzahl, Ivo; Sullivan, Mark; Maguire, Kate; Taubenberger, Stefan; Scalzo, Richard; Ruiter, Ashley; Blagorodnova, Nadejda; Camacho, Yssavo; Castillo, Jayden; Elias-Rosa, Nancy; Fraser, Morgan; Gal-Yam, Avishay; Graham, Melissa; Howell, D Andrew; Inserra, Cosimo; Jha, Saurabh W; Kumar, Sahana; Mazzali, Paolo A; McCully, Curtis; Morales-Garoffolo, Antonia; Pandya, Viraj; Polshaw, Joe; Schmidt, Brian; Smartt, Stephen; Smith, Ken W; Sollerman, Jesper; Spyromilio, Jason; Tucker, Brad; Valenti, Stefano; Walton, Nicholas; Wolf, Christian; Yaron, Ofer; Young, D R; Yuan, Fang; Zhang, Bonnie

    2015-01-01

    The light curves of Type Ia supernovae (SNe Ia) are powered by the radioactive decay of $^{56}$Ni to $^{56}$Co at early times, and the decay of $^{56}$Co to $^{56}$Fe from ~60 days after explosion. We examine the evolution of the [Co III] 5892 A emission complex during the nebular phase for SNe Ia with multiple nebular spectra and show that the line flux follows the square of the mass of $^{56}$Co as a function of time. This result indicates both efficient local energy deposition from positrons produced in $^{56}$Co decay, and long-term stability of the ionization state of the nebula. We compile 77 nebular spectra of 25 SN Ia from the literature and present 17 new nebular spectra of 7 SNe Ia, including SN2014J. From these we measure the flux in the [Co III] 5892 A line and remove its well-behaved time dependence to infer the initial mass of $^{56}$Ni ($M_{Ni}$) produced in the explosion. We then examine $^{56}$Ni yields for different SN Ia ejected masses ($M_{ej}$ - calculated using the relation between light...

  6. Modeling of the EUV and X-Ray Emission Spectra Induced by the Solar Winds Ions in the Heliosphere

    NASA Technical Reports Server (NTRS)

    Kharchenko, Vasili

    2005-01-01

    We have carried out investigation of the EUV and X-ray emission spectra induced in interaction between the Solar Wind (SW) and interstellar neutral gas. The spectra of most important SW ions have been computed for the charge-exchange mechanism of X-ray emission using new accurate spectroscopic data from recent laboratory measurements and theoretical calculations. Total spectra have been constructed as a sum of spectra induced in the charge-exchange collisions by individual O(exp q+), C(exp q+), N(exp q+), Ne(exp q+), Mg (exp q+) and Fe(exp q+) ions. Calculations have been performed for X-ray emission from the heliospheric hydrogen and helium gas. X-ray maps of the heliosphere have been computed. The power density of X-ray sources in the heliospheric ecliptic plane is shown for the H gas and for the He gas. Distances from the Sun (0,0) are given in AU. The helium cone is clear seen in the X-ray map of the charge-exchange emission induced by the solar wind. X-ray emission spectra detected by the Chandra X-ray telescope from the "dark" side of Moon has been identified as a X-ray background emission induced by the solar wind from the geocorona. Spectra and intensities of this charge-exchange X-rays have been compared with the heliospheric component of the X-ray background. Observations and modeling of the SW spectra induced from the geocorona indicate a strong presence of emission lines of highly charged oxygen ions. Anisotropy in distribution of heliospheric X-rays has been predicted and calculated for the regions of the fast and slow solar winds.

  7. Consistency of atomic data for the interpretation of beam emission spectra

    NASA Astrophysics Data System (ADS)

    Delabie, E.; Brix, M.; Giroud, C.; Jaspers, R. J. E.; Marchuk, O.; O'Mullane, M. G.; Ralchenko, Yu; Surrey, E.; von Hellermann, M. G.; Zastrow, K. D.; Contributors, JET-EFDA

    2010-12-01

    Several collisional-radiative (CR) models (Anderson et al 2000 Plasma Phys. Control. Fusion 42 781-806, Hutchinson 2002 Plasma Phys. Control. Fusion 44 71-82, Marchuk et al 2008 Rev. Sci. Instrum. 79 10F532) have been developed to calculate the attenuation and the population of excited states of hydrogen or deuterium beams injected into tokamak plasmas. The datasets generated by these CR models are needed for the modelling of beam ion deposition and (excited) beam densities in current experiments, and the reliability of these data will be crucial to obtain helium ash densities on ITER combining charge exchange and beam emission spectroscopy. Good agreement between the different CR models for the neutral beam (NB) is found, if corrections to the fundamental cross sections are taken into account. First the H? and H? beam emission spectra from JET are compared with the expected intensities. Second, the line ratios within the Stark multiplet are compared with the predictions of a sublevel resolved model. The measured intensity of the full multiplet is ?30% lower than expected on the basis of beam attenuation codes and the updated beam emission rates, but apart from the atomic data this could also be due to the characterization of the NB path and line of sight integration and the absolute calibration of the optics. The modelled n = 3 to n = 4 population agrees very well with the ratio of the measured H? to H? beam emission intensities. Good agreement is found as well between the NB power fractions measured with beam emission in plasma and on the JET Neutral Beam Test Bed. The Stark line ratios and ?/? intensity ratio deviate from a statistical distribution, in agreement with the CR model in parabolic states from Marchuk et al (2010 J. Phys. B: At. Mol. Opt. Phys. 43 011002).

  8. Emissivity Spectra of Meteoritic Powders mixed with Liquid Formamide (NH2COH) at Different Temperatures

    NASA Astrophysics Data System (ADS)

    Raffaele, S.; Maturilli, A.; D'Amore, M.; Ferrari, S.; Helbert, J.

    2013-12-01

    We set-up an experiment at the Planetary Emissivity Laboratory (PEL) to investigate a key aspect in the prebiotic chemistry of formamide: the surface reactivity of minerals used as catalysts. The interaction of formamide and the reaction products on mineral surface, as well as, the sequestration processes in the mineral pores, can facilitate the concentration of products allowing for possible polymerization. Three meteorites, NWA2828 (PEL ID 00000887), Al Haggounia (PEL ID 00000888), and Dhofar959 (PEL ID 00000889), were used in this experiment. All the samples were reduced in the grain size fraction < 125 ?m and stored in a desiccator before measuring. Each sample was poured in one from a set of identical stainless steel cups, having 5 mm thick bottom, internal diameter 50 mm, rim thickness 2 mm, and 20 mm total height. Emissivity of the samples was measured by means of a Bruker Vertex 80V coupled to an emissivity chamber (equipped with a rotating carousel to measure several samples without breaking the vacuum), both evacuable to < 1 mbar. The dry samples were placed in the emissivity chamber, each of them having a temperature sensor in contact with the surface of the sample, reading the effective temperature of the emitting skin. The 'dry' meteorites were measured in vacuum (0.8 mbar) at 70° C on the sample surface, successively liquid formamide was vaporized on the samples surface, the cup was immediately transferred in the emissivity chamber, and evacuated. Each sample was measured at 70°, 100°, 140°, and 200° C. Then each cup was cooled in vacuum and put back in the desiccator. For each sample after this thermal processing, a small amount of heated material was used to fill a cup for reflectance measurements. Since cold reflectance measurements cannot be compared with hot emissivity, those measurements have been taken to better understand the processes happening in the moisturized soil after heating. For all of the samples, when heating at 70°C we noticed in the emissivity spectra strong signatures attributable to liquid formamide. We interpret them as being originated from a column of hot vaporized formamide, lying above the sample surface. For all the samples this effect vanished already at 100°C, probably due to complete evaporation of liquid formamide that was deposited on the meteorite sample surfaces. However, all the spectra measured at 100° and 140° C show signs of the presence of formamide, that we infer from comparing them with the 70° C dry measurement of the same sample. For 2 samples out of 3, when heating at 200°C (and only there) a new feature appears at 7.08 ?m. This band is very close to a similar band that liquid formamide has at 7.19 ?m, and that was even present in all the spectra of wet meteorites taken at 70°C. We interpret this band shift as a possible sign of interaction of formamide with the catalyst (the meteorite powder): the CH bend responsible for that is probably strengthening.

  9. Neutral Gas Temperature Estimates in an Inductively Coupled CF4 Plasma by Fitting Diatomic Emission Spectra

    NASA Technical Reports Server (NTRS)

    Cruden, Brett A.; Rao, M. V. V. S.; Sharma, Surendra P.; Meyyappan, M.

    2001-01-01

    This work examines the accuracy of plasma neutral temperature estimates by fitting the rotational band envelope of different diatomic species in emission. Experiments are performed in an inductively coupled CF4 plasma generated in a Gaseous Electronics Conference reference cell. Visible and ultraviolet emission spectra are collected at a power of 300 W (approximately 0.7 W/cc) and pressure of 30 mtorr. The emission bands of several molecules (CF, CN, C2, CO, and SiF) are fit simultaneously for rotational and vibrational temperatures and compared. Four different rotational temperatures are obtained: 1250 K for CF and CN, 1600 K for CO, 1800 K for C2, and 2300 K for SiF. The vibrational temperatures obtained vary from 1750-5950 K, with the higher vibrational temperatures generally corresponding to the lower rotational temperatures. These results suggest that the different species have achieved different degrees of equilibration between the rotational and vibrational modes and may not be equilibrated with the translational temperatures. The different temperatures are also related to the likelihood that the species are produced by ion bombardment of the surface, with etch products like SiF, CO, and C2 having higher temperatures than species expected to have formed in the gas phase.

  10. Precision Fe K-Alpha and Fe K-Beta Line Spectroscopy of the Seyfert 1.9 Galaxy NGC 2992 with Suzaku

    NASA Technical Reports Server (NTRS)

    Yaqoob, Tahir; Murphy, Kendrah D.; Griffiths, Richard E.; Haba, Yoshito; Inoue, Hajime; Itoh, Takeshi; Kelley, Richard; Kokubun, Motohide; Markowitz, Alex; Mushotzky, Richard; Okajima, Takashi; Ptak, Andrew; Reeves, James; Selemitos, Peter J.; Takahashi, Tadayuki; Terashima, Yuichi

    2006-01-01

    We present detailed time-averaged X-ray spectroscopy in the 0.5-10 keV band of the Seyfert 1.9 galaxy NGC 2992 with the Suzaku X-ray Imaging Spectrometers (XIS). The source had a factor approximately 3 higher 2-10 keV flux (approximately 1.2 x l0(exp -11) erg per square cm per s) than the historical minimum and a factor approximately 7 less than the historical maximum. The XIS spectrum of NGC 2992 can be described by several components. There is a primary continuum, modeled as a power-law with a photon index of Gamma = 1.57(sup +0.06) (sup -0.03) that is obscured by a Compton-thin absorber with a column density of 8.01(sup +0.6) (sup -0.5)x l0 (exp 21) per square cm. . There is another, weaker, unabsorbed power-law component (modeled with the same slope as the primary), that is likely to be due to the primary continuum being electron-scattered into our line-of-sight by a region extended on a scale of hundreds of parsecs. We measure the Thomson depth of the scattering zone to be Tau = 0.072 +/- 0.021. An optically-thin thermal continuum emission component, which probably originates in the same extended region, is included in the model and yields a temperature and luminosity of KT = 0.656(sup +0.088) (sup -0.0.61) keV and approximately 1.2 +/- 0.4 x l0 (exp 40) erg per s respectively. We detect an Fe K emission complex which we model with broad and narrow lines and we show that the intensities of the two components are decoupled at a confidence level > 3 sigma. The broad Fe K alpha line has an equivalent width of 118(sup +32) (sup -61) eV and could originate in an accretion disk (with inclination angle greater than approximately 30 deg) around the putative central black hole. The narrow Fe K alpha line has an equivalent width of 1632(sup +47) (sup -26) eV and is unresolved (FWHM < 4630 km per s) and likely originates in distant matter. The absolute flux in the narrow line implies that the column density out of the line-of-sight could be much higher than measured in the line-of-sight, and that the mean (historically-averaged) continuum luminosity responsible for forming the line could be a factor of several higher than that measured from the data. We also detect the Fe K Beta line (corresponding to the narrow Fe K alpha line) with a high signal-to-noise ratio and describe a new robust method to constrain the ionization state of Fe responsible for the Fe K alpha and Fe K Beta lines that does not require any knowledge of possible gravitational and Doppler energy shifts affecting the line energies. For the distant line-emitting matter (e. g. the putative obscuring torus) we deduce that the predominant ionization state is lower than Fe VIII (at 99% confidence), conservatively taking into account residual calibration uncertainties in the XIS energy scale and theoretical and experimental uncertainties in the Fe K fluorescent line energies. From the limits on a possible Compton-reflection continuum it is likely that the narrow Fe K alpha and Fe K Beta lines originate in a Compton-thin structure.

  11. Reflection and Emission Spectra of Fe-Oxides Under Venus-Like Conditions

    NASA Astrophysics Data System (ADS)

    Bullock, Mark A.; Tsang, Con C. C.; Durda, Dan D.; Kargel, Jeffrey S.

    2015-11-01

    The Solar System’s last solid planet for which we have no mineralogy data is Venus. Soviet landers acquired images and elemental abundances at six locations on the surface of Venus. ?-ray and XRF spectroscopy performed by the landers showed that the plains are made of mafic basalts. Very large concentrations of K at the Venera 8 and 13 landing sites indicated the presence of alkaline basalts.Near-IR and thermal IR remote sensing of Mars, both from orbit and at the surface, have revealed the layered mineralogical complexity of that planet. Dominated by basalts and a wide-variety of fluid-altered phases, the mineralogy of Mars tells a complex story of wet and dry epochs in a history of dramatic climate change.At the surface of Venus, optical pathlengths are small and there is little scattering due to hazes. The environment around a lander or rover on Venus can be mapped from 0.4 to 3 ?m just as well as it has been on Mars. Laboratory spectra show that the ferric edge at 0.55 ?m that makes Mars red shifts to 1 ?m at Venus surface temperatures (Pieters et al., 1986). This spectral feature is caused by strong charge transfer transitions in the UV between overlapping orbitals of iron and oxygen, and crystal-field electronic transition bands of ferric Fe (Pieters and Englert, 1993). Pressure and temperature will alter and broaden crystal-field electronic transition bands. Johnson and Fegley (2000) showed that a halogenated/hydrated amphibole (tremolite) is metastable on Venus; thus, metamorphic remnants of an ancient hydrosphere could still exist. In future work the reflectance and emission spectra of this phase will also be studied at high temperatures.We will present reflection and emission spectra of several Fe-oxides up to 450°C and 100 bars. These environmental conditions are programmable in a small, off-the-shelf 1 cc chamber that sits in the optical path of a Nicolet FTIR spectrometer. Our work will show that ambient pressure and temperature have significant effects on Fe-oxide spectra, and that both must be understood to use near-IR spectroscopy to diagnose the mineralogy near a Venus lander.

  12. Optical vibronic emission spectra for irradiation induced F aggregate centers in single crystal ?-Al2O3

    NASA Astrophysics Data System (ADS)

    Mohammad Saliqur, Rahman Abu Zayed; Awata, T.; Yamashita, N.; Xu, Qiu; Atobe, K.

    The optical vibronic emission spectra of the single crystal ?-Al2O3 caused by neutron bombardment have been studied. New sharp line features near the 470 nm emission band were found. The phonon side band of the previously found zero-phonon line near the 380 nm emission band is also observed in the present study. Vibronic structures associated with the 470 nm emission band are predominantly featured. The Huang-Rhys factor and the Debye temperature are estimated by a curve fitting method to be 3.2 and 710 K, respectively. It can be seen that the origin of the 470 nm vibronic emission spectra is derived from the F./GRAD_A_398864_O_XML_IMAGES/GRAD_A_398864_O_ILM0001.gif type center.

  13. Simulated infrared emission spectra of highly excited polyatomic molecules: a detailed model of the PAH-UIR hypothesis

    NASA Technical Reports Server (NTRS)

    Cook, D. J.; Saykally, R. J.

    1998-01-01

    A detailed description of the polycyclic aromatic hydrocarbon (PAH)/unidentified infrared band (UIR) mechanism is presented in which experimental spectral bandshape functions are used to simulate IR emission spectra for individual molecules. These spectra are additively superimposed to produce a conglomerate spectrum representative of a family of PAH molecules. Ab initio vibrational frequencies and intensities for nine PAHs (neutral and cationic) as large as ovalene are used in conjunction with measured bandshape and temperature-dependent redshift data to simulate the UIR bands. The calculated spectra of cations provide a closer match to the UIRs than do those of the neutrals. However, the PAH cations used in the simulations fail to reproduce the details of the UIR emission spectra. The discrepancies are potentially alleviated if both larger PAHs and a greater number of PAHs were included in the simulation.

  14. Expected gamma-ray emission spectra from the lunar surface as a function of chemical composition

    NASA Technical Reports Server (NTRS)

    Reedy, R. C.; Arnold, J. R.; Trombka, J. I.

    1973-01-01

    The gamma rays emitted from the moon or any similar body carry information on the chemical composition of the surface layer. The elements most easily measured are K, U, Th and major elements such as O, Si, Mg, and Fe. The expected fluxes of gamma ray lines were calculated for four lunar compositions and one chondritic chemistry from a consideration of the important emission mechanisms: natural radioactivity, inelastic scatter, neutron capture, and induced radioactivity. The models used for cosmic ray interactions were those of Reedy and Arnold and Lingenfelter. The areal resolution of the experiment was calculated to be around 70 to 140 km under the conditions of the Apollo 15 and 16 experiments. Finally, a method was described for recovering the chemical information from the observed scintillation spectra obtained in these experiments.

  15. The glassy random laser: replica symmetry breaking in the intensity fluctuations of emission spectra.

    PubMed

    Antenucci, Fabrizio; Crisanti, Andrea; Leuzzi, Luca

    2015-01-01

    The behavior of a newly introduced overlap parameter, measuring the correlation between intensity fluctuations of waves in random media, is analyzed in different physical regimes, with varying amount of disorder and non-linearity. This order parameter allows to identify the laser transition in random media and describes its possible glassy nature in terms of emission spectra data, the only data so far accessible in random laser measurements. The theoretical analysis is performed in terms of the complex spherical spin-glass model, a statistical mechanical model describing the onset and the behavior of random lasers in open cavities. Replica Symmetry Breaking theory allows to discern different kinds of randomness in the high pumping regime, including the most complex and intriguing glassy randomness. The outcome of the theoretical study is, eventually, compared to recent intensity fluctuation overlap measurements demonstrating the validity of the theory and providing a straightforward interpretation of qualitatively different spectral behaviors in different random lasers. PMID:26616194

  16. The glassy random laser: replica symmetry breaking in the intensity fluctuations of emission spectra

    PubMed Central

    Antenucci, Fabrizio; Crisanti, Andrea; Leuzzi, Luca

    2015-01-01

    The behavior of a newly introduced overlap parameter, measuring the correlation between intensity fluctuations of waves in random media, is analyzed in different physical regimes, with varying amount of disorder and non-linearity. This order parameter allows to identify the laser transition in random media and describes its possible glassy nature in terms of emission spectra data, the only data so far accessible in random laser measurements. The theoretical analysis is performed in terms of the complex spherical spin-glass model, a statistical mechanical model describing the onset and the behavior of random lasers in open cavities. Replica Symmetry Breaking theory allows to discern different kinds of randomness in the high pumping regime, including the most complex and intriguing glassy randomness. The outcome of the theoretical study is, eventually, compared to recent intensity fluctuation overlap measurements demonstrating the validity of the theory and providing a straightforward interpretation of qualitatively different spectral behaviors in different random lasers. PMID:26616194

  17. Lyman-alpha emission from the Lyman-alpha forest. [in high red shift quasar spectra due to molecular clouds

    NASA Technical Reports Server (NTRS)

    Hogan, Craig J.; Weymann, Ray J.

    1987-01-01

    It is suggested that high-dispersion long-slit spectra or very narrow-band etalon images of 'blank' sky could reveal patches of Ly-alpha line emission from the population of clouds whose absorption produces the 'Ly-alpha forest' in QSO spectra. A nonobservation can put limits on the ionizing background at high redshift which are better than those obtainable by direct measurements of background light.

  18. Fourier transform infrared emission spectra of MgH and MgD

    NASA Astrophysics Data System (ADS)

    Shayesteh, A.; Appadoo, D. R. T.; Gordon, I.; Le Roy, R. J.; Bernath, P. F.

    2004-06-01

    High resolution Fourier transform infrared emission spectra of MgH and MgD have been recorded. The molecules were generated in an emission source that combines an electrical discharge with a high temperature furnace. Several vibration-rotation bands were observed for all six isotopomers in the X 2?+ ground electronic state: v=1?0 to 4?3 for 24MgH, v=1?0 to 3?2 for 25MgH and 26MgH, v=1?0 to 5?4 for 24MgD, v=1?0 to 4?3 for 25MgD and 26MgD. The new data were combined with the previous ground state data, obtained from diode laser vibration-rotation measurements and pure rotation spectra, and spectroscopic constants were determined for the v=0 to 4 levels of 24MgH and the v=0 to 5 levels of 24MgD. In addition, Dunham constants and Born-Oppenheimer breakdown correction parameters were obtained in a combined fit of the six isotopomers. The equilibrium vibrational constants (?e) for 24MgH and 24MgD were found to be 1492.776(7) cm-1 and 1077.298(5) cm-1, respectively, while the equilibrium rotational constants (Be) are 5.825 523(8) cm-1 and 3.034 344(4) cm-1. The associated equilibrium bond distances (re) were determined to be 1.729 721(1) Å for 24MgH and 1.729 157(1) Å for 24MgD.

  19. Fourier transform infrared emission spectra of MgH and MgD.

    PubMed

    Shayesteh, A; Appadoo, D R T; Gordon, I; Le Roy, R J; Bernath, P F

    2004-06-01

    High resolution Fourier transform infrared emission spectra of MgH and MgD have been recorded. The molecules were generated in an emission source that combines an electrical discharge with a high temperature furnace. Several vibration-rotation bands were observed for all six isotopomers in the X (2)Sigma(+) ground electronic state: v=1-->0 to 4-->3 for (24)MgH, v=1-->0 to 3-->2 for (25)MgH and (26)MgH, v=1-->0 to 5-->4 for (24)MgD, v=1-->0 to 4-->3 for (25)MgD and (26)MgD. The new data were combined with the previous ground state data, obtained from diode laser vibration-rotation measurements and pure rotation spectra, and spectroscopic constants were determined for the v=0 to 4 levels of (24)MgH and the v=0 to 5 levels of (24)MgD. In addition, Dunham constants and Born-Oppenheimer breakdown correction parameters were obtained in a combined fit of the six isotopomers. The equilibrium vibrational constants (omega(e)) for (24)MgH and (24)MgD were found to be 1492.776(7) cm(-1) and 1077.298(5) cm(-1), respectively, while the equilibrium rotational constants (B(e)) are 5.825 523(8) cm(-1) and 3.034 344(4) cm(-1). The associated equilibrium bond distances (r(e)) were determined to be 1.729 721(1) A for (24)MgH and 1.729 157(1) A for (24)MgD. PMID:15268020

  20. Deriving chlorophyll fluorescence emissions of vegetation canopies from high resolution field reflectance spectra

    NASA Astrophysics Data System (ADS)

    Middleton, Elizabeth M.; Corp, Lawrence A.; Daughtry, Craig S.; Entcheva Campbell, Petya K.; Butcher, L. Maryn

    2005-11-01

    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 (ChlF) peaks centered at 685 nm and 735 nm. Methods have been developed elsewhere to extract steady state solar induced fluorescence (SIF) from apparent reflectance of vegetation canopies/landscapes using the Fraunhofer Line Depth (FLD) principal. Our study utilized these methods in conjunction with field-acquired high spectral resolution canopy reflectance spectra obtained in 2004 and 2005 over corn crops and small tree plots of three deciduous species (red maple, tulip poplar, sweet gum). Leaf level measurements were also made of foliage which included ChlF, photosynthesis, and leaf constituents (photosynthetic pigment, carbon (C), and nitrogen (N) contents). As part of ongoing experiments, measurements were made on N application plots within corn (280, 140, 70, and 0 kg N/ha) and tree (0, 37.5, 75, 112.5, 150 kg N /ha) sites at the USDA/Agriculture Research Service in Beltsville, MD. SIF intensities for ChlF were derived directly from canopy reflectance spectra in specific narrow- band regions associated with atmospheric oxygen absorption features centered at 688 and 760 nm. The red/far-red SIF ratio (SIFratio) derived from these field reflectance spectra successfully discriminated foliar pigment ratios altered by N application rates in both corn crops. This ratio was also positively correlated to the C/N ratio at leaf and canopy levels, for the available corn data (e.g., 2004). No consistent N treatment or species differences in SIF were detected in the tree foliage, but additional 2005 data are forthcoming. This study has relevance to future passive satellite remote sensing approaches to monitoring C dynamics from space.

  1. Measuring nickel masses in Type Ia supernovae using cobalt emission in nebular phase spectra

    NASA Astrophysics Data System (ADS)

    Childress, Michael J.; Hillier, D. John; Seitenzahl, Ivo; Sullivan, Mark; Maguire, Kate; Taubenberger, Stefan; Scalzo, Richard; Ruiter, Ashley; Blagorodnova, Nadejda; Camacho, Yssavo; Castillo, Jayden; Elias-Rosa, Nancy; Fraser, Morgan; Gal-Yam, Avishay; Graham, Melissa; Howell, D. Andrew; Inserra, Cosimo; Jha, Saurabh W.; Kumar, Sahana; Mazzali, Paolo A.; McCully, Curtis; Morales-Garoffolo, Antonia; Pandya, Viraj; Polshaw, Joe; Schmidt, Brian; Smartt, Stephen; Smith, Ken W.; Sollerman, Jesper; Spyromilio, Jason; Tucker, Brad; Valenti, Stefano; Walton, Nicholas; Wolf, Christian; Yaron, Ofer; Young, D. R.; Yuan, Fang; Zhang, Bonnie

    2015-12-01

    The light curves of Type Ia supernovae (SNe Ia) are powered by the radioactive decay of 56Ni to 56Co at early times, and the decay of 56Co to 56Fe from ˜60 d after explosion. We examine the evolution of the [Co III] ?5893 emission complex during the nebular phase for SNe Ia with multiple nebular spectra and show that the line flux follows the square of the mass of 56Co as a function of time. This result indicates both efficient local energy deposition from positrons produced in 56Co decay and long-term stability of the ionization state of the nebula. We compile SN Ia nebular spectra from the literature and present 21 new late-phase spectra of 7 SNe Ia, including SN 2014J. From these we measure the flux in the [Co III] ?5893 line and remove its well-behaved time dependence to infer the initial mass of 56Ni (MNi) produced in the explosion. We then examine 56Ni yields for different SN Ia ejected masses (Mej - calculated using the relation between light-curve width and ejected mass) and find that the 56Ni masses of SNe Ia fall into two regimes: for narrow light curves (low stretch s ˜ 0.7-0.9), MNi is clustered near MNi ? 0.4 M? and shows a shallow increase as Mej increases from ˜1 to 1.4 M?; at high stretch, Mej clusters at the Chandrasekhar mass (1.4 M?) while MNi spans a broad range from 0.6 to 1.2 M?. This could constitute evidence for two distinct SN Ia explosion mechanisms.

  2. Detection of cervical cancer by fluorescence emission and stokes' shift spectra of blood and urine

    NASA Astrophysics Data System (ADS)

    Masilamani, V.; Vijmasi, T.; AlSalhi, M.; Govindarajan, K.; VijayaRaghavan, A. P.; Rai, Ram Rathan

    2011-03-01

    In this paper we present the results of a study to distinguish cervical cancer patients [ N=50] from healthy subjects [N=50] based on the Fluorescence Emission Spectra [FES] and Stokes' Shift Spectra [SSS] of blood and urine. FES was obtained from the cellular fraction of blood and urine by excitation at 400 nm. SSS was obtained from blood plasma and urine with ?? of 70nm. In the FES of blood cellular fraction, the ratio of intensity of the two bands due to neutral porphyrin and basic porphyrin [I630 / I580] was 1 for normal controls and 3 for cervical cancers. In the SSS of plasma, the average ratio of intensity of the two bands due to tryptophan and collagen [I305 nm / I340 nm] was 1.9 for normal controls, 1.1 for early cervical cancers and 0.9 for advanced cervical cancers In the SSS of urine, the ratio of intensity of the two bands due to flavin and NADH [I450 nm / I360 nm] was 0.2 for normal controls and 0.8 for cancer patients. A discriminant analysis combining all three parameters showed a sensitivity of 80% and specificity of 78% for this technique. In this study we show that fluorescence spectroscopy of blood and urine could develop into a promising technique for non-invasive diagnosis and screening of cervical cancers and would appropriately supplement or complement currently used techniques.

  3. Molecular phonons and their absorption/emission spectra from the far-IR to microwaves

    NASA Astrophysics Data System (ADS)

    Papoular, R.

    2015-07-01

    Together with their fingerprint modes, molecules carry coherent vibrations of all their atoms (phonons). Phonon spectra extend from ˜20 to more than 104 ?m, depending on molecular size. These spectra are discrete but large assemblies of molecules of the same family, differing only by minor structural details, will produce continua. As such assemblies are expected to exist in regions where dust accumulates, they are bound to contribute to the observed continua underlying the unidentified infrared bands and the 21 ?m band of planetary nebulae as well as to the diffuse galactic emission surveyed by the Planck astronomical satellite and other means. The purpose of this work is to determine, for carbon-rich molecules, the intensity of such continua and their extent into the millimetric range, and to evaluate their detectability in this range. The rules governing the spectral distributions of phonons are derived and shown to differ from those which obtain in the solid state. Their application allows the extinction cross-section per H atom, and its maximum wavelength, to be determined as a function of molecular size and dimensionality. Chemical modelling of more than 15 large molecules illustrates these results. It is found that the maximum phonon wavelength of a 2D structure increases roughly as the square of its larger dimension. Spectral energy distributions were computed as far as 4000 ?m, for molecules up to 50 Å in length.

  4. K-(alpha) X-ray Thomson Scattering From Dense Plasmas

    SciTech Connect

    Kritcher, A L; Neumayer, P; Castor, J; Doppner, T; Falcone, R W; Landen, O L; Lee, H J; Lee, R W; Morse, E C; Ng, A; Pollaine, S; Price, D; Glenzer, S H

    2009-05-07

    Spectrally resolved Thomson scattering using ultra-fast K-{alpha} x-rays has measured the compression and heating of shocked compressed matter. The evolution and coalescence of two shock waves traveling through a solid density LiH target were characterized by the elastic scattering component. The density and temperature at shock coalescence, 2.2 eV and 1.7 x 10{sup 23}cm{sup -3}, were determined from the plasmon frequency shift and the relative intensity of the elastic and inelastic scattering features in the collective scattering regime. The observation of plasmon scattering at coalescence indicates a transition to the dense metallic state in LiH. The density and temperature regimes accessed in these experiments are relevant for inertial confinement fusion experiments and for the study of planetary formation.

  5. K-alpha X-ray Thomson Scattering From Dense Plasmas

    SciTech Connect

    Kritcher, Andrea L.; Neumayer, Paul; Castor, John; Doeppner, Tilo; Landen, Otto L.; Ng, Andrew; Pollaine, Steve; Price, Dwight; Glenzer, Siegfried H.; Falcone, Roger W.; Ja Lee, Hae; Lee, Richard W.; Morse, Edward C.

    2009-09-10

    Spectrally resolved Thomson scattering using ultra-fast K-alpha x rays has measured the compression and heating of shocked compressed matter. The evolution and coalescence of two shock waves traveling through a solid density LiH target were characterized by the elastic scattering component. The density and temperature at shock coalescence, 2.2 eV and 1.7x10{sup 23} cm{sup -3}, were determined from the plasmon frequency shift and the relative intensity of the elastic and inelastic scattering features in the collective scattering regime. The observation of plasmon scattering at coalescence indicates a transition to the dense metallic state in LiH. The density and temperature regimes accessed in these experiments are relevant for inertial confinement fusion experiments and for the study of planetary formation.

  6. X-ray resonant photoexcitation: line widths and energies of K{\\alpha} transitions in highly charged Fe ions

    E-print Network

    Rudolph, J K; Epp, S W; Steinbrügge, R; Beilmann, C; Brown, G V; Eberle, S; Graf, A; Harman, Z; Hell, N; Leutenegger, M; Müller, A; Schlage, K; Wille, H -C; Yavas, H; Ullrich, J; López-Urrutia, J R Crespo

    2013-01-01

    Photoabsorption by and fluorescence of the K{\\alpha} transitions in highly charged iron ions are essential mechanisms for X-ray radiation transfer in astrophysical environments. We study photoabsorption due to the main K{\\alpha} transitions in highly charged iron ions from heliumlike to fluorinelike (Fe 24+...17+) using monochromatic X-rays around 6.6 keV at the PETRA III synchrotron photon source. Natural linewidths were determined with hitherto unattained accuracy. The observed transitions are of particular interest for the understanding of photoexcited plasmas found in X-ray binaries and active galactic nuclei.

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

    PubMed Central

    Keenan, Francis P.; Aller, Lawrence H.; Ramsbottom, Catherine A.; Bell, Kenneth L.; Crawford, Fergal L.; Hyung, Siek

    2000-01-01

    Electron impact excitation rates in Cl III, recently determined with the R-matrix code, are used to calculate electron temperature (Te) and density (Ne) emission line ratios involving both the nebular (5517.7, 5537.9 ?) and auroral (8433.9, 8480.9, 8500.0 ?) transitions. A comparison of these results with observational data for a sample of planetary nebulae, obtained with the Hamilton Echelle Spectrograph on the 3-m Shane Telescope, reveals that the R1 = I(5518 ?)/I(5538 ?) intensity ratio provides estimates of Ne in excellent agreement with the values derived from other line ratios in the echelle spectra. This agreement indicates that R1 is a reliable density diagnostic for planetary nebulae, and it also provides observational support for the accuracy of the atomic data adopted in the line ratio calculations. However the [Cl iii] 8433.9 ? line is found to be frequently blended with a weak telluric emission feature, although in those instances when the [Cl iii] intensity may be reliably measured, it provides accurate determinations of Te when ratioed against the sum of the 5518 and 5538 ? line fluxes. Similarly, the 8500.0 ? line, previously believed to be free of contamination by the Earth's atmosphere, is also shown to be generally blended with a weak telluric emission feature. The [Cl iii] transition at 8480.9 ? is found to be blended with the He i 8480.7 ? line, except in planetary nebulae that show a relatively weak He i spectrum, where it also provides reliable estimates of Te when ratioed against the nebular lines. Finally, the diagnostic potential of the near-UV [Cl iii] lines at 3344 and 3354 ? is briefly discussed. PMID:10759562

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

    PubMed

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

    2000-04-25

    Electron impact excitation rates in Cl III, recently determined with the R-matrix code, are used to calculate electron temperature (T(e)) and density (N(e)) emission line ratios involving both the nebular (5517.7, 5537.9 A) and auroral (8433.9, 8480.9, 8500.0 A) transitions. A comparison of these results with observational data for a sample of planetary nebulae, obtained with the Hamilton Echelle Spectrograph on the 3-m Shane Telescope, reveals that the R(1) = I(5518 A)/I(5538 A) intensity ratio provides estimates of N(e) in excellent agreement with the values derived from other line ratios in the echelle spectra. This agreement indicates that R(1) is a reliable density diagnostic for planetary nebulae, and it also provides observational support for the accuracy of the atomic data adopted in the line ratio calculations. However the [Cl iii] 8433.9 A line is found to be frequently blended with a weak telluric emission feature, although in those instances when the [Cl iii] intensity may be reliably measured, it provides accurate determinations of T(e) when ratioed against the sum of the 5518 and 5538 A line fluxes. Similarly, the 8500.0 A line, previously believed to be free of contamination by the Earth's atmosphere, is also shown to be generally blended with a weak telluric emission feature. The [Cl iii] transition at 8480.9 A is found to be blended with the He i 8480.7 A line, except in planetary nebulae that show a relatively weak He i spectrum, where it also provides reliable estimates of T(e) when ratioed against the nebular lines. Finally, the diagnostic potential of the near-UV [Cl iii] lines at 3344 and 3354 A is briefly discussed. PMID:10759562

  9. Fluorescence Excitation-Emission Matrix Regional Integration to Quantify Spectra for Dissolved Organic Matter

    USGS Publications Warehouse

    Chen, W.; Westerhoff, P.; Leenheer, J.A.; Booksh, K.

    2003-01-01

    Excitation-emission matrix (EEM) fluorescence spectroscopy has been widely used to characterize dissolved organic matter (DOM) in water and soil. However, interpreting the >10,000 wavelength-dependent fluorescence intensity data points represented in EEMs has posed a significant challenge. Fluorescence regional integration, a quantitative technique that integrates the volume beneath an EEM, was developed to analyze EEMs. EEMs were delineated into five excitation-emission regions based on fluorescence of model compounds, DOM fractions, and marine waters or freshwaters. Volumetric integration under the EEM within each region, normalized to the projected excitation-emission area within that region and dissolved organic carbon concentration, resulted in a normalized region-specific EEM volume (??i,n). Solid-state carbon nuclear magnetic resonance (13C NMR), Fourier transform infrared (FTIR) analysis, ultraviolet-visible absorption spectra, and EEMs were obtained for standard Suwannee River fulvic acid and 15 hydrophobic or hydrophilic acid, neutral, and base DOM fractions plus nonfractionated DOM from wastewater effluents and rivers in the southwestern United States. DOM fractions fluoresced in one or more EEM regions. The highest cumulative EEM volume (??T,n = ????i,n) was observed for hydrophobic neutral DOM fractions, followed by lower ??T,n values for hydrophobic acid, base, and hydrophilic acid DOM fractions, respectively. An extracted wastewater biomass DOM sample contained aromatic protein- and humic-like material and was characteristic of bacterial-soluble microbial products. Aromatic carbon and the presence of specific aromatic compounds (as indicated by solid-state 13C NMR and FTIR data) resulted in EEMs that aided in differentiating wastewater effluent DOM from drinking water DOM.

  10. Modified spontaneous emission spectra of laser dye in inverse opal photonic crystals Henry P. Schriemer,* Henry M. van Driel,

    E-print Network

    Vos, Willem L.

    Modified spontaneous emission spectra of laser dye in inverse opal photonic crystals Henry P crystals made of inverse opals in titania (TiO2). We identify stop bands with large relative widths of 15 constants 15,16 . These so-called air-sphere crystals, or inverse opals, interact so strongly with light

  11. Chlorophyll Fluorescence Emissions of Vegetation Canopies From High Resolution Field Reflectance Spectra

    NASA Technical Reports Server (NTRS)

    Middleton, E. M.; Corp, L. A.; Daughtry, C. S. T.; Campbell, P. K. Entcheva

    2006-01-01

    A two-year experiment was performed on corn (Zea mays L.) crops under nitrogen (N) fertilization regimes to examine the use of hyperspectral canopy reflectance information for estimating chlorophyll fluorescence (ChlF) and vegetation production. 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 ChlF peaks centered at 685V10 nm and 735V5 nm. Methods have been developed elsewhere to extract steady state solar induced fluorescence (SF) from apparent reflectance of vegetation canopies/landscapes using the Fraunhofer Line Depth (FLD) principal. Our study utilized these methods in conjunction with field-acquired high spectral resolution canopy reflectance spectra obtained in 2004 and 2005 over corn crops, as part of an ongoing multi-year experiment at the USDA/Agriculture Research Service in Beltsville, MD. A spectroradiometer (ASD-FR Fieldspec Pro, Analytical Spectral Devices, Inc., Boulder, CO) was used to measure canopy radiances 1 m above plant canopies with a 22deg field of view and a 0deg nadir view zenith angle. Canopy and plant measurements were made at the R3 grain fill reproductive stage on 3-4 replicate N application plots provided seasonal inputs of 280, 140, 70, and 28 kg N/ha. Leaf level measurements were also made which included ChlF, photosynthesis, and leaf constituents (photosynthetic pigment, carbon (C), and N contents). Crop yields were determined at harvest. SIF intensities for ChlF were derived directly from canopy reflectance spectra in specific narrowband regions associated with atmospheric oxygen absorption features centered at 688 and 760 nm. The red/far-red S F ratio derived from these field reflectance spectra successfully discriminated foliar pigment levels (e.g., total chlorophyll, Chl) associated with N application rates in both corn crops. This canopy-level spectral ratio was also positively correlated to the foliar C/N ratio (r = 0.89, n = go), as was a leaf-level steady state fluorescence ratio (Fs/Chl, r = 0.92). The latter ratio was inversely correlated with crop grain yield (Kg 1 ha) (r = 0.9). This study has relevance to future passive satellite remote sensing approaches to monitoring C dynamics from space.

  12. Single particle size and fluorescence spectra from emissions of burning materials in a tube furnace to simulate burn pits

    NASA Astrophysics Data System (ADS)

    Pan, Yong-Le; Houck, Joshua D. T.; Clark, Pamela A.; Pinnick, Ronald G.

    2013-08-01

    A single-particle fluorescence spectrometer (SPFS) and an aerodynamic particle sizer were used to measure the fluorescence spectra and particle size distribution from the particulate emissions of 12 different burning materials in a tube furnace to simulate open-air burning of garbage. Although the particulate emissions are likely dominated by particles <1 ?m diameter, only the spectra of supermicron particles were measured here. The overall fluorescence spectral profiles exhibit either one or two broad bands peaked around 300-450 nm within the 280-650 nm spectral range, when the particles are illuminated with a 263-nm laser. Different burning materials have different profiles, some of them (cigarette, hair, uniform, paper, and plastics) show small changes during the burning process, and while others (beef, bread, carrot, Styrofoam, and wood) show big variations, which initially exhibit a single UV peak (around 310-340 nm) and a long shoulder in visible, and then gradually evolve into a bimodal spectrum with another visible peak (around 430-450 nm) having increasing intensity during the burning process. These spectral profiles could mainly derive from polycyclic aromatic hydrocarbons with the combinations of tyrosine-like, tryptophan-like, and other humic-like substances. About 68 % of these single-particle fluorescence spectra can be grouped into 10 clustered spectral templates that are derived from the spectra of millions of atmospheric aerosol particles observed in three locations; while the others, particularly these bimodal spectra, do not fall into any of the 10 templates. Therefore, the spectra from particulate emissions of burning materials can be easily discriminated from that of common atmospheric aerosol particles. The SFFS technology could be a good tool for monitoring burning pit emissions and possibly for distinguishing them from atmospheric aerosol particles.

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

    ERIC Educational Resources Information Center

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

    2011-01-01

    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…

  14. Simulation of emission spectra from nonuniform reactive laser-induced plasmas

    NASA Astrophysics Data System (ADS)

    Hermann, Jörg; Lorusso, Antonella; Perrone, Alessio; Strafella, Francesco; Dutouquet, Christophe; Torralba, Béatrice

    2015-11-01

    We demonstrate that chemical reactions leading to the formation of AlO radicals in plasmas produced by ablation of aluminum or Ti-sapphire with ultraviolet nanosecond laser pulses can be predicted by the model of local thermodynamic equilibrium. Therefore, emission spectra recorded with an echelle spectrometer and a gated detector were compared to the spectral radiance computed for uniform and nonuniform equilibrium plasmas. The calculations are based on analytical solutions of the radiation transfer equation. The simulations show that the plasmas produced in argon background gas are almost uniform, whereas temperature and density gradients are evidenced in air. Furthermore, chemical reactions exclusively occur in the cold plume periphery for ablation in air. The formation of AlO is negligible in argon as the plasma temperature is too large in the time interval of interest up to several microseconds. Finally, the validity of local thermodynamic equilibrium is shown to depend on time, space, and on the elemental composition. The presented conclusions are of interest for material analysis via laser-induced breakdown spectroscopy and for laser materials processing.

  15. Comparison of Cathodoluminescent and Photoluminescent Emission Spectra of LuPO4 with Different Dopants

    SciTech Connect

    Goedeke, Shawn; Hollerman, William Andrew; Allison, Stephen W; Gray, P A; Lewis, Linda A; Smithwick III, Robert W; Boatner, Lynn A; Glasgow, David C; Wise, H.

    2008-01-01

    The current interest in returning human exploration to the Moon and Mars makes cost-effective and low-mass health monitoring sensors essential for spacecraft development. In space, there are many surface measurements that are required to monitor the condition of the spacecraft including: surface temperature, radiation dose, and impact. Through the use of tailored phosphors, these conditions can be monitored. Practical space-based phosphor sensors will depend heavily upon research investigating the resistance of phosphors to ionizing radiation and their ability to anneal or 'self-heal' from damage caused by ionizing radiation. For the present research, a group of lutetium orthophosphate (LuPO{sub 4}) crystals with dopants including europium, erbium, and neodymium were characterized. Cathodoluminescence (CL) testing was performed using the low energy electron system located at the NASA Marshall Space Flight Center in Huntsville, Alabama. The data were collected using an Ocean Optics HR4000 spectrometer and a fiber optic feed-through. Previous research has shown that increases in both beam energy and current density improved the CL fluorescence yield. While the total electron dose was small, the intention was to maximize the number of irradiated materials. Additionally, these samples were evaluated using a PTI Quantum Master Spectrophotometer to determine the photoluminescence emission spectra.

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

    SciTech Connect

    Kovacevic, Jelena; Popovic, Luka C.; Dimitrijevic, Milan S.

    2010-07-15

    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.

  17. Ultrafast K-(alpha) X-ray Thomson Scattering from Shock Compressed Lithium Hydride

    SciTech Connect

    Kritcher, A L; Neumayer, P; Castor, J; Doeppner, T; Falcone, R W; Landen, O L; Lee, H J; Lee, R W; Holst, B; Redmer, R; Morse, E C; Ng, A; Pollaine, S; Price, D; Glenzer, S H

    2008-12-10

    Spectrally and temporally resolved x ray Thomson scattering using ultrafast Ti K-{alpha} x-rays has 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. 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 for experiments such as on the National Ignition Facility (NIF), LLNL.

  18. The ‘Excess’ Emission from the Warm Surface Adjacent to Active Fissures on Enceladus from Combined VIMS and CIRS Spectra

    NASA Astrophysics Data System (ADS)

    Goguen, Jay D.; Buratti, Bonnie J.; Howell, Robert R.

    2015-11-01

    The exciting discovery of thermal emission from the tiger stripe fissures at the S. pole of Enceladus is a major highlight of the Cassini mission. Both VIMS (Visible and Infrared Mapping Spectrometer) and CIRS (Composite InfraRed Spectrometer) detect the thermal ‘blackbody’ spectrum emitted from the warm fissure areas. The VIMS instrument is uniquely suited to measuring the hottest active locations because VIMS covers the 3 to 5 micron wavelength range where the rising edge of the Planck function for these T~200 K areas dominates the emission spectrum. At longer wavelengths, the spectrum is more complicated because contributions from small hot areas and larger cooler areas combine to form the broad emission spectrum that is detected by the CIRS instrument at wavelengths >6.7 microns. It is the combination of VIMS and CIRS spectra that paint a more complete portrait of the fissure heat transfer processes. Using spectra that span both the VIMS and CIRS wavelengths places a stronger constraint on the T distribution near the fissures than consideration of the spectra from either instrument alone.We show that when the best (= highest spatial resolution, 800 m/pixel and smaller) VIMS and CIRS spectra of the fissure thermal emission are considered together, there is a large (up to 400%) component of ‘excess’ emission spanning 7 to 17 microns that requires explanation. New analysis of ~2 km spatial resolution VIMS spectra of the Damascus hot spot on 8/13/2010 are similar to the highest resolution 4/14/2012 VIMS Baghdad spectra, confirming that differences in location or time between the best VIMS and CIRS spectra do not explain away the excess. The obvious interpretation is that there are processes that transfer heat from the fissure eruption to the surface within 400 m of the fissure center in addition to heat conduction through the fissure walls. Candidate heat transfer processes include fallback of large warm low velocity ice particles from the edges of the plume, and condensation of the low velocity component of water vapor expanding outward from the edge of the plume.This research was conducted at the Jet Propulsion Laboratory, California Institute of Technolgy, Pasadena, CA.

  19. (??1) ? (??1), (??1) emission spectra of chlorofluorobenzene cations in the gaseous phase and their lifetimes in the (0o) states

    USGS Publications Warehouse

    Maier, John Paul; Marthaler, O.; Mohraz, Manijeh; Shiley, R.H.

    1980-01-01

    The radiative decay of seventeen electronically excited chlorofluorobenzene cations in the gaseous phase has been detected. The reported emission spectra, which have been obtained using low energy electron beam excitation, are assigned to the B(??-1 ??? X(??-1 electronic transitions of these cations on the basis of their Ne(I) photoelectron spectra. In another sixteen chloroflourobenzene cations, the B ??? X radiative decay could not be detected, from which is inferred that the B states are now associated with Cl 3p(??-1 ionisation processes. The lifetimes of the studied cations in the lowest vibrational levels of the B(??-1 state have been measured. ?? 1980.

  20. MID-INFRARED ATOMIC FINE-STRUCTURE EMISSION-LINE SPECTRA OF LUMINOUS INFRARED GALAXIES: SPITZER/IRS SPECTRA OF THE GOALS SAMPLE

    SciTech Connect

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

    2013-11-10

    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]{sub 18.7{sub ?m}}, [O IV], [Fe II], [S III]{sub 33.5{sub ?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{sub ?}, and ionization parameters of 2-8 × 10{sup 7} cm s{sup –1}. Based on the [S III]{sub 33.5{sub ?m}}/[S III]{sub 18.7{sub ?m}} ratios, the electron density in LIRG nuclei is typically one to a few hundred cm{sup –3}, with a median electron density of ?300 cm{sup –3}, 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 s{sup –1}) 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 s{sup –1}. 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]{sub 12.8{sub ?m}} and [Ne III]{sub 15.5{sub ?m}} emission, as well as [S III]{sub 33.5{sub ?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.

  1. Excitation Emission Matrix Spectra (EEMS) of Chromophoric Dissolved Organic Matter Produced during Microbial Incubation

    NASA Astrophysics Data System (ADS)

    McDonald, N.; Nelson, N. B.; Parsons, R.

    2013-12-01

    The chromophoric or light-absorbing fraction of dissolved organic matter (CDOM) is present ubiquitously in natural waters and has a significant impact on ocean biogeochemistry, affecting photosynthesis and primary production as well direct and indirect photochemical reactions (Siegel et al., 2002; Nelson et al., 2007). It has been largely researched in the past few decades, however the exact chemical composition remains unknown. Instrumental methods of analysis including simultaneous excitation-emission fluorescence spectra have allowed for further insight into source and chemical composition. While certain excitation-emission peaks have been associated with ';marine' sources, they have not been exclusively linked to bacterial production of CDOM (Coble, 1996; Zepp et al., 2004). In this study, ';grazer diluted' seawater samples (70% 0.2?m filtered water; 30% whole water) were collected at the Bermuda Atlantic Time Series (BATS) site in the Sargasso Sea (31° 41' N; 64° 10' W) and incubated with an amendment of labile dissolved organic carbon (10?M C6H12O6), ammonium (1?M NH4Cl) and phosphate (0.1?M K2HPO4) to facilitate bacterial production. These substrates and concentrations have been previously shown to facilitate optimum bacterial and CDOM production (Nelson et al., 2004). Sample depths were chosen at 1m and 200m as water at these depths has been exposed to UV light (the Subtropical Mode Water at 200m has been subducted from the surface) and therefore has low initial concentrations of CDOM. After the samples were amended, they were incubated at in-situ temperatures in the dark for 72 hours, with bacteria counts, UV-Vis absorption and EEMS measurements taken at 6-8 hour intervals. Dissolved organic carbon (DOC) measurements were collected daily. For the surface water experiment specific bacteria populations were investigated using Fluorescence In-Situ Hybridization (FISH) analysis. Results showed a clear production of bacteria and production of CDOM, which can be linked to this bacterial production. FISH analysis showed percentage abundance of Pelagibacter ubique (SAR 11) and of Alteromonas. On-going and future work will ascertain if specific microbial communities produce CDOM more readily than others, and if these different populations produce varying fluorescence peaks, thus indicating a range of chromophoric groups being produced by bacteria. An additional suite of probes will be used for further FISH analysis to identify percentages of other populations, and seasonal/temporal variations will be investigated.

  2. Effect of heat treatment on the far-infrared emission spectra and fine structures of black tourmaline.

    PubMed

    Meng, Junping; Liang, Jinsheng; Liu, Jie; Ding, Yan; Gan, Kun

    2014-05-01

    Mineral black tourmaline powders were heat-treated at different temperatures. Their crystal structure was studied by X-ray diffractometer. Their infrared absorption and emission spectra before and after the heat treatment were analyzed by the Fourier transform infrared spectrometer. The corresponding fine structures were discussed in detail. The results showed that the powders possessed higher infrared emissivity at the band where they showed stronger infrared absorption. However, there is no certain correlation between the peak intensity of infrared absorption and emissivity values at the same frequency. Because of the crystal shrinkage of c-axis, the electronic transitions were stimulated between different energy levels, and the abilities of infrared absorption and emission were enhanced with increasing the temperature of heat treatment. PMID:24734598

  3. Mid-Infrared Atomic Fine-Structure Emission Line Spectra of Luminous Infrared Galaxies: Spitzer/IRS Spectra of the GOALS Sample

    E-print Network

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

    2013-01-01

    We present the data and our analysis of MIR fine-structure emission lines detected in Spitzer/IRS high-res spectra of 202 local LIRGs observed as part of the GOALS project. We detect emission lines of [SIV], [NeII], [NeV], [NeIII], [SIII]18.7, [OIV], [FeII], [SIII]33.5, and [SiII]. Over 75% of our galaxies are classified as starburst (SB) sources in the MIR. We compare ratios of the emission line fluxes to stellar photo- and shock-ionization models to constrain the gas properties in the SB nuclei. Comparing the [SIV]/[NeII] and [NeIII]/[NeII] ratios to the Starburst99-Mappings III models with an instantaneous burst history, the line ratios suggest that the SB in our LIRGs have ages of 1-4.5Myr, metallicities of 1-2Z_sun, and ionization parameters of 2-8e7cm/s. Based on the [SIII]/[SIII] ratios, the electron density in LIRG nuclei has a median electron density of ~300cm-3 for sources above the low density limit. We also find that strong shocks are likely present in 10 SB sources. A significant fraction of the ...

  4. Evolution on K{alpha} in Fe and L{beta} satellites in Au in SPring-8

    SciTech Connect

    Shigeoka, Nobuyuki; Oohashi, Hirofumi; Ito, Yoshiaki; Vlaicu, Aurel M.; Nisawa, Atsushi; Yoshikawa, Hideki; Fukushima, Sei; Watanabe, Mamoru

    2003-08-26

    With the advent of the third generation synchrotron radiation, we can perform experiments on the threshold behavior of the satellites including the excitation dynamics in atoms. Especially, x-ray emission spectroscopy is a suitable tool to study the satellites on the electron correlation. The contributions of direct ionization, i.e, the shake-off process in Fe and indirect ionization of Coster-Kronig transition in Au have not been investigated to the x-ray emission spectra yet. We present the contribution of the spectator holes to the processes around the threshold.

  5. Paradigms and challenges for bioapplication of rare earth upconversion luminescent nanoparticles: small size and tunable emission/excitation spectra.

    PubMed

    Sun, Ling-Dong; Wang, Ye-Fu; Yan, Chun-Hua

    2014-04-15

    Rare earth (RE) materials, which are excited in the ultraviolet and emit in the visible light spectrum, are widely used as phosphors for lamps and displays. In the 1960's, researchers reported an abnormal emission phenomenon where photons emitted from a RE element carried more energy than those absorbed, owing to the sequential energy transfer between two RE ions--Yb(3+)-sensitized Er(3+) or Tm(3+)--in the solid state. After further study, researchers named this abnormal emission phenomenon upconversion (UC) emission. More recent approaches take advantage of solution-based synthesis, which allows creation of homogenous RE nanoparticles (NPs) with controlled size and structure that are capable of UC emission. Such nanoparticles are useful for many applications, especially in biology. For these applications, researchers seek small NPs with high upconversion emission intensity. These UCNPs have the potential to have multicolor and tunable emissions via various activators. A vast potential for future development remains by developing molecular antennas and energy transfer within RE ions. We expect UCNPs with optimized spectra behavior to meet the increasing demand of potential applications in bioimaging, biological detection, and light conversion. This Account focuses on efforts to control the size and modulate the spectra of UCNPs. We first review efforts in size control. One method is careful control of the synthesis conditions to manipulate particle nucleation and growth, but more recently researchers have learned that the doping conditions can affect the size of UCNPs. In addition, constructing homogeneous core/shell structures can control nanoparticle size by adjusting the shell thickness. After reviewing size control, we consider how diverse applications impose different requirements on excitation and/or emission photons and review recent developments on tuning of UC spectral profiles, especially the extension of excitation/emission wavelengths and the adjustment and purification of emission colors. We describe strategies that employ various dopants and others that build rationally designed nanostructures and nanocomposites to meet these goals. As the understanding of the energy transfer in the UC process has improved, core/shell structures have been proved useful for simultaneous tuning of excitation and emission wavelengths. Finally, we present a number of typical examples to highlight the upconverted emission in various applications, including imaging, detection, and sensing. We believe that with deeper understanding of emission phenomena and the ability to tune spectral profiles, UCNPs could play an important role in light conversion studies and applications. PMID:24422455

  6. Neutron Emission Spectra of Some Structural Fusion Materials at 26.8 and 45.2 MeV Alpha Incident Energies

    NASA Astrophysics Data System (ADS)

    Kaplan, A.; Aydin, A.; Tel, E.; Büyükuslu, H.

    2010-08-01

    In this study, neutron-emission spectra produced by ( ?, xn) reactions for some structural fusion materials such as 27Al, 53Cr, 56Fe and 58,60,62Ni have been investigated. Hybrid model, geometry dependent hybrid model and full exciton model have been used to calculate the pre-equilibrium neutron-emission spectra. For the reaction equilibrium component, Weisskopf-Ewing model calculations have been preferred. The mean free path parameter's effect for ( ?, xn) neutron-emission spectra has been examined. The obtained results have been discussed and compared with the available experimental data and found agreement with each other.

  7. Analysis of H2 Emission from Mira B in UV Spectra from HST

    E-print Network

    Brian E. Wood; Margarita Karovska; John C. Raymond

    2002-08-09

    We analyze Ly-alpha fluoresced H2 lines observed in the UV spectrum of Mira B. We identify 13 different sequences fluoresced by 13 different H2 transitions within the Ly-alpha line. The observed H2 line ratios within these sequences imply significant line opacity, so we use a Monte Carlo radiative transfer code to model the line ratios, correcting for opacity effects. We find the observed line ratios can best be reproduced by assuming that the H2 is fluoresced in a layer between the observer and Mira B with a temperature and column density of T=3600 K and log N(H2)=17.3, respectively. The strengths of H2 absorption features within the Ly-alpha line are roughly consistent with this temperature and column. We use the total flux fluoresced within the 13 sequences to infer the Ly-alpha profile seen by the H2. In order to explain differences between the shape of this and the observed profile, we have to assume that the observed profile suffers additional interstellar (or circumstellar) H I Ly-alpha absorption with a column density of about log N(H I)=20.35. We also have to assume that the observed profile is about a factor of 2.5 lower in flux than the profile seen by the H2, and a couple possible explanations for this behavior are presented. Several lines of evidence lead us to tentatively attribute the fluoresced emission to H2 that is heated in a photodissociation front within Mira A's wind a few AU from Mira B, although it is possible that interaction between the winds of Mira A and B may also play a role in heating the H2. We estimate a Mira B mass loss rate of 5e-13 solar masses per year and a terminal velocity of 250 km/s, based on wind absorption features in the Mg II h & k lines. We note, however, that the wind is variable and IUE Mg II spectra suggest significantly higher mass loss rates during the IUE era.

  8. Investigating Possible Departures from Maxwellian Energy Distributions in Nebulae using High-Resolution Emission Line Spectra

    NASA Astrophysics Data System (ADS)

    Turbyfill, Amanda; Dinerstein, H. L.; Sterling, N. C.

    2014-01-01

    The derivation of ionic abundance ratios from collisionally excited emission lines in gaseous nebulae requires knowledge of the physical state of the gas, particularly the electron kinetic temperature, Te, to which the resulting abundances are highly sensitive. A long-standing problem in nebular analyses has been pervasive discrepancies among values of Te obtained from different diagnostic ratios for a single nebula. Recently, Nicholls et al. (2012, ApJ, 752, 148) have suggested that the nebular electrons may not obey an equilibrium Maxwell-Boltzmann (M-B) energy distribution, but instead follow a “? distribution” seen in many solar system plasmas, a family of distributions for which the M-B distribution is the limiting case where ? ? ?. The high-energy tail of supra-thermal electrons in ? distributions have a disproportionate effect on strongly energy dependent quantities, such as Te diagnostics, for even modest departures from M-B distributions. We apply prescriptions given by Nicholls et al. (2013, ApJS, 207, 21) to high-resolution (R=36,700) optical spectra of 10 planetary nebulae obtained with the 2d-coudé echelle spectrograph on the 2.7 m Harlan J. Smith Telescope at McDonald Observatory. The advantages of these data include their broad spectral coverage and sufficiently high spectral resolution to separate blended lines and assess possible atmospheric absorption issues. The line fluxes were obtained using ROBOSPECT, an automated spectral line measurement package developed by Waters & Hollek (2013, PASP, 125, 1164). We solve both for Te under the assumption of M-B distributions, and the parameters of ? distributions consistent with the data. Our goal is to test whether the ? distribution hypothesis provides a better fit to the observed line ratios. Finally, we discuss effects on the derived ionic abundances under this alternate description of the particle energy distributions. This research was supported by NSF grant AST 0708245 and the John W. Cox Endowment for Advanced Studies in Astronomy at the University of Texas at Austin.

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

    SciTech Connect

    Tingay, S. J.; Wayth, R. B.

    2011-06-15

    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.

  10. Deconstructing the room-temperature emission spectra of nanocrystals using Photon-Correlation Fourier Spectroscopy

    E-print Network

    Cui, Jian, Ph. D. Massachusetts Institute of Technology

    2014-01-01

    The photoluminescence spectrum of an ensemble of emitters is the result of the homogeneous "natural" spectra of single emitters subjected to interparticle inhomogeneities and perturbations from the environment. For ...

  11. BROADBAND X-RAY SPECTRA OF TWO LOW-LUMINOSITY ACTIVE GALACTIC NUCLEI NGC 1566 AND NGC 4941 OBSERVED WITH SUZAKU

    SciTech Connect

    Kawamuro, Taiki; Ueda, Yoshihiro; Tazaki, Fumie; Terashima, Yuichi

    2013-06-20

    We report the first broadband X-ray spectra of the low-luminosity active galactic nuclei (LLAGNs), NGC 1566 (type 1.5) and NGC 4941 (type 2), observed with Suzaku and Swift/BAT covering the 0.5-195 keV band. Both targets have hard X-ray luminosities of {approx}10{sup 41-42} erg s{sup -1} in the 15-55 keV band. The spectra of the nucleus are well reproduced by a sum of partially or fully covered transmitted emission and its reflection from the accretion disk, reprocessed emission from the torus accompanied by a strong narrow iron-K{alpha} line, and a scattered component (for NGC 4941). We do not significantly detect a broad iron-K{alpha} line from the inner accretion disk in both targets, and obtain an upper limit on the corresponding solid angle of {Omega}/2{pi} < 0.3 in NGC 1566. The reflection strength from the torus is moderate, {Omega}/2{pi}=0.45{sup +0.13}{sub -0.10} in NGC 1566 and {Omega}/2{pi}=0.64{sup +0.69}{sub -0.27} in NGC 4941. Comparison of the equivalent width of the narrow iron-K{alpha} line with a model prediction based on a simple torus geometry constrains its half-opening angle to be {theta}{sub oa} {approx_equal} 60 Degree-Sign -70 Degree-Sign in NGC 4941. These results agree with the obscured AGN fraction obtained from hard X-ray and mid-infrared selected samples at similar luminosities. Our results support the implication that the averaged covering fraction of AGN tori is peaked at L {approx} 10{sup 42-43} erg s{sup -1} but decreases toward lower luminosities.

  12. On the Early Time X-ray Spectra of Swift Afterglows I: Evidence for Anomalous Soft X-ray Emission

    E-print Network

    Butler, N R

    2006-01-01

    We have conducted a thorough and blind search for emission lines in >70 Swift X-ray afterglows of total exposure ~10^7s. We find that most afterglows are consistent with pure power-laws plus extinction. Significant outliers to the population exist at the 5-10% level and have anomalously soft, possibly thermal spectra. Four bursts are singled out via detections of 2-5 lines: GRBs 060218, 060202, 050822, and 050714B. The most significant soft component detections in the full data set of ~2000 spectra correspond to GRB060218/SN2006aj, with significances ranging up to ~20sigma. A thermal plasma model fit to the data indicates that the flux is primarily due to L-shell transitions of Fe at ~solar abundance. We associate (>4sigma significant) line emission from the 3 other events with K-shell transitions in light metals. We favor a model where the line emission in these afterglows arises from the mildly relativistic cocoon of matter surrounding the GRB jet as it penetrates and exits the surface of the progenitor sta...

  13. Effects of Incident Electron Fluence and Energy on the Election Yield Curves and Emission Spectra of Dielectrics

    NASA Technical Reports Server (NTRS)

    Sim, Alec; Dennison, J. R.; Thomson, Clint

    2005-01-01

    We present an experimental study of evolution of electron emission yields and spectra as a result of internal charge build up due to electron dose. Reliable total, backscattered and secondary yield curves and electron emission spectra for un-charged insulators using a low fluence, pulsed electron beam (= or < 5 microsec at = or < 3 nA/sq mm or = or < 10(exp 5) e/sq mm per pulse) with low energy electron and UV flooding to neutralize the charging between pulses. Quantifiable changes in yield curves are observed due to < 100 fC/sq mm fluences for several excellent dielectric thin film materials. We find good agreement with a phenomenological argument based on insulator charging predicted by the yield curve; this includes an approximately linear decrease in the magnitude of the yield as incident energies approach the crossover energies and an exponential decrease in yield as accumulated internal charge reduces the landing energy to asymptotically approach a steady state surface charge and unity yield. We also find that the exponential decay of yield curves with fluence exhibit an energy dependent decay constant, alpha(E), over a broad range of incident energies below, between and above the crossover energies. Finally, we present some preliminary physics-based models for this energy dependence and attempt to relate our charging measurements to knowledge of how charge is deposited within the insulator, the mechanisms for charge trapping and transport, and how the profile of trapped charge affects the transport and emission of charges from insulators.

  14. An empirical model for predicting the absolute radiative emission and absorption spectra of xenon flashlamps

    SciTech Connect

    Jancaitis, K.S.; Powell, H.T.

    1987-10-22

    We have developed an updated quasi-stationary model for radiative properties of xenon flashlamps which adequately describes all of the experimental data (approximately 75 spectra) obtained for preionized lamps operated at a pulsewidth greater than 300 ..mu..s. The form of this model is such that it may be easily used to predict both the single-pass pumping and heating of solid-state laser media. To this end, we have implemented the lamp model in a menu-driven program (described in the appendix) for IBM-compatible micro-computers which predicts both the instantaneous and time-averaged output of the flashlamp as well as the interaction of the lamp radiation with an arbitrary laser medium. Calculations performed using the spectra from this model agree quite well (i.e., a maximum deviation of between 10 and 15%) with those obtained using experimentally measured spectra. 10 refs., 5 figs., 1 tab.

  15. Spitzer Secondary Eclipse Observations of Five Cool Gas Giant Planets and Empirical Trends in Cool Planet Emission Spectra

    NASA Astrophysics Data System (ADS)

    Kammer, Joshua A.; Knutson, Heather A.; Line, Michael R.; Fortney, Jonathan J.; Deming, Drake; Burrows, Adam; Cowan, Nicolas B.; Triaud, Amaury H. M. J.; Agol, Eric; Desert, Jean-Michel; Fulton, Benjamin J.; Howard, Andrew W.; Laughlin, Gregory P.; Lewis, Nikole K.; Morley, Caroline V.; Moses, Julianne I.; Showman, Adam P.; Todorov, Kamen O.

    2015-09-01

    In this work we present Spitzer 3.6 and 4.5 ?m secondary eclipse observations of five new cool (\\lt 1200 K) transiting gas giant planets: HAT-P-19b, WASP-6b, WASP-10b, WASP-39b, and WASP-67b. We compare our measured eclipse depths to the predictions of a suite of atmosphere models and to eclipse depths for planets with previously published observations in order to constrain the temperature- and mass-dependent properties of gas giant planet atmospheres. We find that the dayside emission spectra of planets less massive than Jupiter require models with efficient circulation of energy to the night side and/or increased albedos, while those with masses greater than that of Jupiter are consistently best-matched by models with inefficient circulation and low albedos. At these relatively low temperatures we expect the atmospheric CH4/CO ratio to vary as a function of metallicity, and we therefore use our observations of these planets to constrain their atmospheric metallicities. We find that the most massive planets have dayside emission spectra that are best-matched by solar metallicity atmosphere models, but we are not able to place strong constraints on metallicities of the smaller planets in our sample. Interestingly, we find that the ratio of the 3.6 and 4.5 ?m brightness temperatures for these cool transiting planets is independent of planet temperature, and instead exhibits a tentative correlation with planet mass. If this trend can be confirmed, it would suggest that the shape of these planets’ emission spectra depends primarily on their masses, consistent with the hypothesis that lower-mass planets are more likely to have metal-rich atmospheres.

  16. Hot topic: Innovative lactation-stage-dependent prediction of methane emissions from milk mid-infrared spectra.

    PubMed

    Vanlierde, A; Vanrobays, M-L; Dehareng, F; Froidmont, E; Soyeurt, H; McParland, S; Lewis, E; Deighton, M H; Grandl, F; Kreuzer, M; Gredler, B; Dardenne, P; Gengler, N

    2015-08-01

    The main goal of this study was to develop, apply, and validate a new method to predict an indicator for CH4 eructed by dairy cows using milk mid-infrared (MIR) spectra. A novel feature of this model was the consideration of lactation stage to reflect changes in the metabolic status of the cow. A total of 446 daily CH4 measurements were obtained using the SF6 method on 142 Jersey, Holstein, and Holstein-Jersey cows. The corresponding milk samples were collected during these CH4 measurements and were analyzed using MIR spectroscopy. A first derivative was applied to the milk MIR spectra. To validate the novel calibration equation incorporating days in milk (DIM), 2 calibration processes were developed: the first was based only on CH4 measurements and milk MIR spectra (independent of lactation stage; ILS); the second included milk MIR spectra and DIM information (dependent on lactation stage; DLS) by using linear and quadratic modified Legendre polynomials. The coefficients of determination of ILS and DLS equations were 0.77 and 0.75, respectively, with standard error of calibration of 63g/d of CH4 for both calibration equations. These equations were applied to 1,674,763 milk MIR spectra from Holstein cows in the first 3 parities and between 5 and 365 DIM. The average CH4 indicators were 428, 444, and 448g/d by ILS and 444, 467, and 471g/d by DLS for cows in first, second, and third lactation, respectively. Behavior of the DLS indicator throughout the lactations was in agreement with the literature with values increasing between 0 and 100 DIM and decreasing thereafter. Conversely, the ILS indicator of CH4 emission decreased at the beginning of the lactation and increased until the end of the lactation, which differs from the literature. Therefore, the DLS indicator seems to better reflect biological processes that drive CH4 emissions than the ILS indicator. The ILS and DLS equations were applied to an independent data set, which included 59 respiration chamber measurements of CH4 obtained from animals of a different breed across a different production system. Results indicated that the DLS equation was much more robust than the ILS equation allowing development of indicators of CH4 emissions by dairy cows. Integration of DIM information into the prediction equation was found to be a good strategy to obtain biologically meaningful CH4 values from lactating cows by accounting for biological changes that occur throughout the lactation. PMID:26026761

  17. The similar emission-line spectra of the young star LkH-alpha 101 and the hypergiant MWC 300

    SciTech Connect

    Hamann, F.; Persson, S.E. )

    1989-12-01

    High-resolution spectra from 0.63 to 1.75 microns are presented, showing that the luminous young star LkH-alpha 101 and the post-main-sequence hypergiant MWC 300 have very similar emission-line properties. Tables are given of line measurements and identifications. It is found that, in spite of their different histories, these stars have similar conditions of density, temperature, kinematics, and possibly geometry in their line-emitting envelopes. The results support models of hypergiants and luminous young stars which both invoke dense equatorial disks and suggest that disk structures around some evolved hot young stars are created by dense equatorial winds. 74 refs.

  18. Neutron Capture Cross Sections and Gamma Emission Spectra from Neutron Capture on 234,236,238U Measured with DANCE

    NASA Astrophysics Data System (ADS)

    Ullmann, J. L.; Mosby, S.; Bredeweg, T. A.; Couture, A. J.; Haight, R. C.; Jandel, M.; Kawano, T.; O'Donnell, J. M.; Rundberg, R. S.; Vieira, D. J.; Wilhelmy, J. B.; Wu, C.-Y.; Becker, J. A.; Chyzh, A.; Baramsai, B.; Mitchell, G. E.; Krticka, M.

    2014-05-01

    A new measurement of the 238U(n, ?) cross section using a thin 48 mg/cm2 target was made using the DANCE detector at LANSCE over the energy range from 10 eV to 500 keV. The results confirm earlier measurements. Measurements of the gamma-ray emission spectra were also made for 238U(n, ?) as well as 234,236U(n, ?). These measurements help to constrain the radiative strength function used in the cross-section calculations.

  19. L{beta}1 and L{beta}2 Satellites in the X-ray Emission Spectra

    SciTech Connect

    Poonia, Surendra

    2005-10-26

    The X-ray satellites L{beta}{sub 1}{sup I}, L{beta}{sub 1}{sup II}, L{beta}{sub 1}{sup III}, L{beta}{sub 1}{sup IV}, L{beta}{sub 2}{sup I}, L{beta}{sub 2}{sup (b)}, L{beta}{sub 2}{sup II} and L{beta}{sub 2}{sup (c)} observed in the L-emission spectra in elements with Z = 26 to 92, have been calculated. The energies of various transitions have been calculated by available Hartree-Fock-Slater (HFS) data using the semi-empirical Auger transition energies in the doubly ionized atoms and their relative intensities have been estimated by considering cross - sections of singly ionized 2x-1 (x {identical_to} s, p) states and then of subsequent Coster-Kronig and shake off processes. The calculated spectra have been compared with the measured satellite energies in the L emission spectra. Their intense peaks have been identified as the observed satellite lines. The one to one correspondence between the peaks in calculated spectra and the satellites in measured spectra has been established on the basis of the agreement between the separations in the peak energies and those in the measured satellite energies. Group of transitions under the transition schemes L2Mx-MxM4,5 and L3Mx-MxN4,5 (x {identical_to} 1-5), which give rise to these satellites have been identified. It is observed that the satellite L{beta}{sub 2}{sup (b)} in all these spectra can be assigned to the superposition of 3F4-3G5 and 3F4-3D3 transitions and that this must be most intense one out of all these satellites, contributing in order of decreasing intensity. Each of the remaining satellites is found to have different origin in different elements. The possible contributions of the suitable transitions to all these lines have also been discussed.

  20. Analysis of emission spectra of Ho{sup 3+}:LFBCd glasses

    SciTech Connect

    Naresh, V. Buddhudu, S.

    2014-04-24

    In the present paper, we report on the absorption and emission properties of (0.1-1.5 mol %) Ho{sup 3+} doped LFBCd (Li{sub 2}O{sub ?}LiF{sub ?}B{sub 2}O{sub 3?}CdO) glasses prepared via melt quenching method. On exciting these glasses at (?{sub exci}) = 452 nm, two emissions at 556 nm ({sup 5}S{sub 2}?{sup 5}I{sub 8}; Green), 655 nm ({sup 5}F{sub 5}?{sup 5}I{sub 8}; Red) have been obtained. Upon exciting these glasses with a 980 nm diode laser, NIR emissions at 1195 nm ({sup 5}I{sub 6}?{sup 5}I{sub 8}), 1951 nm ({sup 5}I{sub 7}?{sup 5}I{sub 8}) have been measured for 1 mol % Ho{sup 3+}:LFBCd glass. For higher concentration beyond 1.0 mol %, emission quenching of Ho{sup 3+} glass has been noticed and which has successfully been explained in terms of an energy level diagram. From absorption cross-section data, stimulated emission cross-section has been evaluated by applying McCumber's theory and further cross-sectional gain has also been computed for the emissions at 1195 nm (?1.20 ?m) and 1951 nm (?2.0 ?m) of 1 mol % Ho{sup 3+}:LFBCd glass.

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

    SciTech Connect

    Sargent, B. A.; Forrest, W.; Watson, Dan M.; Kim, K. H.; Richter, I.; Tayrien, C.; D'Alessio, P.; Calvet, N.; Furlan, E.; Green, J.; Pontoppidan, K.

    2014-09-10

    We present spectra of 13 T Tauri stars in the Taurus-Auriga star-forming region showing emission in Spitzer Space Telescope Infrared Spectrograph 5-7.5 ?m spectra from water vapor and absorption from other gases in these stars' protoplanetary disks. Seven stars' spectra show an emission feature at 6.6 ?m due to the ?{sub 2} = 1-0 bending mode of water vapor, with the shape of the spectrum suggesting water vapor temperatures >500 K, though some of these spectra also show indications of an absorption band, likely from another molecule. This water vapor emission contrasts with the absorption from warm water vapor seen in the spectrum of the FU Orionis star V1057 Cyg. The other 6 of the 13 stars have spectra showing a strong absorption band, peaking in strength at 5.6-5.7 ?m, which for some is consistent with gaseous formaldehyde (H{sub 2}CO) and for others is consistent with gaseous formic acid (HCOOH). There are indications that some of these six stars may also have weak water vapor emission. Modeling of these stars' spectra suggests these gases are present in the inner few AU of their host disks, consistent with recent studies of infrared spectra showing gas in protoplanetary disks.

  2. Emission and absorption spectra of some bridged 1,5-benzodiazepines

    NASA Astrophysics Data System (ADS)

    Mellor, J. M.; Pathirana, R. N.; Stibbard, J. H. A.

    Absorption spectra in neutral and acidic media are reported for a series of bridged 1,5-benzodiazepines, which are unable to tautomerize. Comparison is made with non-bridged 1,5-benzodiazepines capable of tautomeric rearrangement. Both bridged and non-bridged 1,5-benzodiazepines are essentially non-fluorescent due to the "proximity effect" of interaction between singlet ??* and ??* states of similar energy, a phenomenon previously recognised in six-membered nitrogen heterocycles.

  3. Broadening and splitting of emission spectra of a GaInAs/AlInAs quantum cascade laser in a quantising magnetic field

    SciTech Connect

    Zasavitskii, I I; Pashkeev, D A; Bushuev, E V; Mikaelyan, G T

    2013-02-28

    We have studied the effect of a relatively weak quantising magnetic field on emission spectra of a GaInAs/AlInAs quantum cascade laser near 10 K. The results demonstrate that, as the magnetic field induction increases to 7 T, the spectra broaden (to 5 meV) and split into three emission bands. As a result, we observe simultaneously up to 80 longitudinal lasing modes in the three bands and the integrated laser output intensity increases 70 times. The presence of bands in the emission spectra can be accounted for in terms of the magnetic quantisation of the laser levels into spinsplit Landau levels. The increase in emission intensity is attributable primarily to phonon resonance adjustment in a magnetic field. (lasers)

  4. Experimental study on the emission spectra of microwave plasma at atmospheric pressure

    SciTech Connect

    Zhang, Boya; Wang, Qiang; Zhang, Guixin; Liao, Shanshan

    2014-01-28

    An experimental study on microwave plasma at atmospheric pressure was conducted by employing optical emission spectroscopy. Based on a microwave plasma generation device developed for nanoparticle synthesis, we studied the influence of input microwave power and gas flow rate on the optical emission behaviors and electron temperature of plasma using Ar, He, and N{sub 2} as working gas, respectively. The physics behind these behaviors was discussed. The results are useful in characterizing microwave plasma at atmospheric pressure and can be used for improving nanoparticle synthesis system for commercial use in the future.

  5. Long-term X-ray studies of Sco X-1. [emission spectra of constellations

    NASA Technical Reports Server (NTRS)

    Holt, S. S.; Boldt, E. A.; Serlemitsos, P. J.; Kaluzienski, L. J.

    1975-01-01

    No modulation of the 3-6 keV X-ray intensity of Sco X-1 at a level of excess of 1% was observed at the optical period of .787313d. Evidence is found for shot-noise character in a large fraction of the X-ray emission. Almost all of the Sco X-1 emission can be synthesized in terms of approximately 200 shots per day, each with a duration of approximately 1/3 day. A pinhole camera was used to obtain data and the data were statistically analyzed.

  6. On the Early Time X-ray Spectra of Swift Afterglows I: Evidence for Anomalous Soft X-ray Emission

    E-print Network

    Nathaniel R. Butler

    2006-11-03

    We have conducted a thorough and blind search for emission lines in >70 Swift X-ray afterglows of total exposure ~10^7s. We find that most afterglows are consistent with pure power-laws plus extinction. Significant outliers to the population exist at the 5-10% level and have anomalously soft, possibly thermal spectra. Four bursts are singled out via possible detections of 2-5 lines: GRBs 060218, 060202, 050822, and 050714B. Alternatively, a blackbody model with kT~0.1-0.5 keV can describe the soft emission in each afterglow. The most significant soft component detections in the full data set of ~2000 spectra correspond to GRB060218/SN2006aj, with line significances ranging up to \\~20-sigma. A thermal plasma model fit to the data indicates that the flux is primarily due to L-shell transitions of Fe at ~ solar abundance. We associate (>4-sigma significant) line triggers in the 3 other events with K-shell transitions in light metals. We favor a model where the possible line emission in these afterglows arises from the mildly relativistic cocoon of matter surrounding the GRB jet as it penetrates and exits the surface of the progenitor star. The emitting material in each burst is at a similar distance \\~10^12--10^13 cm, a similar density ~10^17 cm^-3, and subject to a similar flux of ionizing radiation. The lines may correlate with the X-ray flaring. For the blackbody interpretation, the soft flux may arise from break out of the GRB shock or plasma cocoon from the progenitor stellar wind, as recently suggested for GRB060218 (Campana et al. 2006). Due to the low z of GRB060218, bursts faint in Gamma-rays with fluxes dominated by this soft X-ray component could outnumber classical GRBs 100-1.

  7. 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...

  8. Study of medical isotope production facility stack emissions and noble gas isotopic signature using automatic gamma-spectra analysis platform

    NASA Astrophysics Data System (ADS)

    Zhang, Weihua; Hoffmann, Emmy; Ungar, Kurt; Dolinar, George; Miley, Harry; Mekarski, Pawel; Schrom, Brian; Hoffman, Ian; Lawrie, Ryan; Loosz, Tom

    2013-04-01

    The nuclear industry emissions of the four CTBT (Comprehensive Nuclear-Test-Ban Treaty) relevant radioxenon isotopes are unavoidably detected by the IMS along with possible treaty violations. Another civil source of radioxenon emissions which contributes to the global background is radiopharmaceutical production companies. To better understand the source terms of these background emissions, a joint project between HC, ANSTO, PNNL and CRL was formed to install real-time detection systems to support 135Xe, 133Xe, 131mXe and 133mXe measurements at the ANSTO and CRL 99Mo production facility stacks as well as the CANDU (CANada Deuterium Uranium) primary coolant monitoring system at CRL. At each site, high resolution gamma spectra were collected every 15 minutes using a HPGe detector to continuously monitor a bypass feed from the stack or CANDU primary coolant system as it passed through a sampling cell. HC also conducted atmospheric monitoring for radioxenon at approximately 200 km distant from CRL. A program was written to transfer each spectrum into a text file format suitable for the automatic gamma-spectra analysis platform and then email the file to a server. Once the email was received by the server, it was automatically analysed with the gamma-spectrum software UniSampo/Shaman to perform radionuclide identification and activity calculation for a large number of gamma-spectra in a short period of time (less than 10 seconds per spectrum). The results of nuclide activity together with other spectrum parameters were saved into the Linssi database. This database contains a large amount of radionuclide information which is a valuable resource for the analysis of radionuclide distribution within the noble gas fission product emissions. The results could be useful to identify the specific mechanisms of the activity release. The isotopic signatures of the various radioxenon species can be determined as a function of release time. Comparison of 133mXe and 133Xe activity ratios showed distinct differences between the closed CANDU primary coolant system and radiopharmaceutical production releases. According to the concept proposed by Kalinowski and Pistner (2006), the relationship between different isotopic activity ratios based on three or four radioxenon isotopes was plotted in a log-log diagram for source characterisation (civil vs. nuclear test). The multiple isotopic activity ratios were distributed in three distinct areas: HC atmospheric monitoring ratios extended to far left; the CANDU primary coolant system ratios lay in the middle; and 99Mo stack monitoring ratios for ANSTO and CRL were located on the right. The closed CANDU primary coolant has the lowest logarithmic mean ratio that represents the nuclear power reactor operation. The HC atmospheric monitoring exhibited a broad range of ratios spreading over several orders of magnitude. In contrast, the ANSTO and CRL stack emissions showed the smallest range of ratios but the results indicate at least two processes involved in the 99Mo productions. Overall, most measurements were found to be shifted towards the reactor domain. The hypothesis is that this is due to an accumulation of the isotope 131mXe in the stack or atmospheric background as it has the longest half-life and extra 131mXe emissions from the decay of 131I. The contribution of older 131mXe to a fresh release shifts the ratio of 133mXe/131mXe to the left. It was also very interesting to note that there were some situations where isotopic ratios from 99Mo production emissions fell within the nuclear test domain. This is due to operational variability, such as shorter target irradiation times. Martin B. Kalinowski and Christoph Pistner, (2006), Isotopic signature of atmospheric xenon released from light water reactors, Journal of Environmental Radioactivity, 88, 215-235.

  9. Light emission spectra of molecules in negative and positive back discharges in nitrogen with carbon dioxide mixture at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Czech, Tadeusz; Sobczyk, Arkadiusz Tomasz; Jaworek, Anatol

    2015-10-01

    Results of spectroscopic investigations and current-voltage characteristics of back discharge generated in point-plane electrode geometry with plate covered fly ash layer in a mixture of N2 + CO2 at atmospheric pressure, for positive and negative polarity of the discharge electrode are presented in this paper. Point-plane electrode configuration was chosen in these studies in order to simulate the physical processes occurring in electrostatic precipitator. Three forms of back discharge for both polarities were investigated: glow, streamers and low-current back-arc. Diatomic reactions and dissociation products of N2 and CO2 (OH, NO, CN), atoms from fly ash layer (N, Ti, Na), free radicals, molecules or ions, which have unpaired valence electrons, and other active species, e.g., N2 (in C,B,A-state), N 2 + (B) were identified in the discharges by the method of optical emission spectroscopy (OES). The measurements shown that atomic and molecular optical emission spectral lines from back discharge depend on the forms of discharge and the discharge current. In normal electrical discharges, the emission spectra are dominated by gaseous components, but in the case of back discharge, atomic lines belonging to chemical compounds of fly ash were also recorded and identified.

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

    SciTech Connect

    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

    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.

  11. Auroral Processes at the Giant Planets: Energy Deposition, Emission Mechanisms, Morphology and Spectra

    NASA Astrophysics Data System (ADS)

    Badman, Sarah V.; Branduardi-Raymont, Graziella; Galand, Marina; Hess, Sébastien L. G.; Krupp, Norbert; Lamy, Laurent; Melin, Henrik; Tao, Chihiro

    The ionospheric response to auroral precipitation at the giant planets is reviewed, using models and observations. The emission processes for aurorae at radio, infrared, visible, ultraviolet, and X-ray wavelengths are described, and exemplified using ground- and space-based observations. Comparisons between the emissions at different wavelengths are made, where possible, and interpreted in terms of precipitating particle characteristics or atmospheric conditions. Finally, the spatial distributions and dynamics of the various components of the aurorae (moon footprints, low-latitude, main oval, polar) are related to magnetospheric processes and boundaries, using theory, in situ, and remote observations, with the aim of distinguishing between those related to internally-driven dynamics, and those related to the solar wind interaction.

  12. Auroral Processes at the Giant Planets: Energy Deposition, Emission Mechanisms, Morphology and Spectra

    NASA Astrophysics Data System (ADS)

    Badman, Sarah V.; Branduardi-Raymont, Graziella; Galand, Marina; Hess, Sébastien L. G.; Krupp, Norbert; Lamy, Laurent; Melin, Henrik; Tao, Chihiro

    2015-04-01

    The ionospheric response to auroral precipitation at the giant planets is reviewed, using models and observations. The emission processes for aurorae at radio, infrared, visible, ultraviolet, and X-ray wavelengths are described, and exemplified using ground- and space-based observations. Comparisons between the emissions at different wavelengths are made, where possible, and interpreted in terms of precipitating particle characteristics or atmospheric conditions. Finally, the spatial distributions and dynamics of the various components of the aurorae (moon footprints, low-latitude, main oval, polar) are related to magnetospheric processes and boundaries, using theory, in situ, and remote observations, with the aim of distinguishing between those related to internally-driven dynamics, and those related to the solar wind interaction.

  13. Emission spectra and relaxation dynamics of excited XZBr2 in Ar and Kr matrices

    SciTech Connect

    Mandich, M.; Beeken, P.; Flynn, G.

    1982-07-15

    The photochemical dynamics of Br2 trapped in Ar and Kr matrices have been studied. Following laser excitation into either the B TPI(O/sub u/ ) or PI(1u) states, emission occurs in the near infrared spectral region. Analysis of this emission indicates that it consists of three electronic transitions which have been assigned. The spectral and temporal data are consistent with an overall energy transfer mechanism involving both vibration and electronic relaxation. The intramolecular electronic relaxation is somewhat restricted in that the highest lying B TPI(O/sub u/ ) state is populated only by direct absorption into its bound and continuum levels, whereas the two low states A TPI(1u) and A' TPI(2u) acquire population after either the PI(1u) or BTPI(O/sub u/ ) states are initially excited. Both the initial vibration and electronic relaxation rapidly (<20 ns) routes the excited population into the lowest nu' = 0 levels of the A and B states (and tentatively A'), where subsequent decay occurs on a 10 W-10 Ss time scale. All of the observed emission lifetimes are independent of temperature, laser power and Br2: matrix dilutions ranging from 1:500-1:10 000. 69 references, 7 figures, 3 tables.

  14. Bright light therapy in focus: lamp emission spectra and ocular safety.

    PubMed

    Remé, C E; Rol, P; Grothmann, K; Kaase, H; Terman, M

    1996-12-01

    In recent years, bright light treatment of seasonal affective disorder (SAD), recurrent depressions in fall and winter, has been discovered. Newer applications include circadian sleep phase disorder, shift work and jet lag. Apart from creating the visual signal, light can modify retinal structure and physiology. UV and visible light lead to distinct lesions of ocular tissues under certain experimental und naturalistic conditions. In light therapy, a large variety of fixtures is used but the spectral emission of lamps is mostly unknown to the user and clinician leading to the potential hazard of ocular lesions. Therefore, we have analyzed a wide selection of light sources commonly used for treatment. We measured the spectral emission and calculated irradiant doses for several light therapy regimens. Based on these measurements, potential hazards are analyzed, physiological mechanisms of light action are discussed and safety measures for bright light therapy are proposed. They include recommendations for lamps devoid of damaging spectral emissions and standardized therapy fixtures, ophthalmological monitoring of patients with eye diseases and control by optometrists for patients with healthy eyes who are likely to undergo light treatment for extended periods. PMID:9042691

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

    SciTech Connect

    Han, I.; Demir, L.

    2010-06-15

    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.

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

    SciTech Connect

    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

    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.

  17. New method for measuring time-resolved spectra of lanthanide emission using square-wave excitation

    SciTech Connect

    Qin, Feng; Zhao, Hua; Cai, Wei; Duan, Qianqian; Zhang, Zhiguo; Cao, Wenwu

    2013-11-15

    A method using modulated continuous wave (CW) visible laser to measure time-resolved fluorescence spectra of trivalent rare-earth ions has been developed. Electro-optic modulator was used to modulate the CW pumping laser with a rise time of 2 ?s. CW Nd{sup 3+} lasers were used as examples to present the method. Upconversion dynamic process of Ho{sup 3+} was studied utilizing a 532 nm CW laser. Quantum cutting dynamic process from Tb{sup 3+} to Yb{sup 3+} was analyzed by a 473 nm CW laser. This method can be applied to any CW laser such as He-Ne laser, Ar{sup +} laser, Kr{sup +} laser, Ti:sapphire laser, etc.

  18. The equilibrium and preequilibrium neutron-emission spectra of some structural fusion materials for (n, xn) reactions up to 16 MeV energy

    SciTech Connect

    Kaplan, A.; Tel, E.; Aydin, A.

    2009-06-15

    In this study, neutron-emission spectra produced by (n, xn) reactions for some structural fusion materials as {sup 27}Al, {sup 51}V, {sup 52}Cr, {sup 55}Mn, and {sup 56}Fe have been investigated by a neutron beam up to 16 MeV. Multiple preequilibrium mean-free-path constant from internal transition and the preequilibrium and equilibrium level-density parameters have been investigated for some (n, xn) neutron-emission spectra calculated in this study. Preequilibrium neutron-emission spectra were calculated by using new-evaluated hybrid model and geometry-dependent hybrid model, full-exciton model, and cascade-exciton model. The reaction equilibrium component was calculated by Weisskopf-Ewing model. The obtained results have been discussed and compared with the available experimental data and found agreement with each other.

  19. Theoretical emission line ratios for [Fe III] and [Fe VII] applicable to the optical and infrared spectra of gaseous nebulae

    PubMed Central

    Keenan, Francis P.; Aller, Lawrence H.; Ryans, Robert S. I.; Hyung, Siek

    2001-01-01

    Recent calculations of electron impact excitation rates and Einstein A-coefficients for transitions among the 3d6 levels of Fe III and among the 3d2 levels of Fe VII are used to derive theoretical emission line ratios applicable to the optical and infrared spectra of gaseous nebulae. Results for [Fe III] are generated for electron temperatures Te = 7,000–20,000 K and densities Ne = 102-108 cm?3, whereas those for [Fe VII] are provided for Te = 10,000–30,000 K and Ne = 102-108 cm?3. The theoretical line ratios are significantly different in some instances from earlier calculations and resolve discrepancies between theory and observation found for the planetary nebulae IC 4997 and NGC 7027. PMID:11493676

  20. Theoretical emission line ratios for [Fe III] and [Fe VII] applicable to the optical and infrared spectra of gaseous nebulae.

    PubMed

    Keenan, F P; Aller, L H; Ryans, R S; Hyung, S

    2001-08-14

    Recent calculations of electron impact excitation rates and Einstein A-coefficients for transitions among the 3d(6) levels of Fe III and among the 3d(2) levels of Fe VII are used to derive theoretical emission line ratios applicable to the optical and infrared spectra of gaseous nebulae. Results for [Fe III] are generated for electron temperatures T(e) = 7,000-20,000 K and densities N(e) = 10(2)-10(8) cm(-3), whereas those for [Fe VII] are provided for T(e) = 10,000-30,000 K and N(e) = 10(2)-10(8) cm(-3). The theoretical line ratios are significantly different in some instances from earlier calculations and resolve discrepancies between theory and observation found for the planetary nebulae IC 4997 and NGC 7027. PMID:11493676

  1. Investigation of Deuteron Emission Spectra at 62 MeV Proton Incident Energy

    NASA Astrophysics Data System (ADS)

    Aydin, A.; Türeci, G.; Tel, E.; Kaplan, A.

    2010-08-01

    In this study, deuteron emission cross sections for 27Al, 54,56Fe, 89Y, 120Sn, 197Au, 208Pb and 209Bi target nuclei have been calculated at 62 MeV proton incident energy. In these calculations, the pre-equilibrium and equilibrium effects have been investigated. The pre-equilibrium calculations involve the geometry dependent hybrid model and hybrid model. Equilibrium effects are calculated according to the Weisskopf-Ewing model. The calculated results are compared with the experimental data taken from the literature and found to be in good agreement.

  2. X-Ray Reflected Spectra from Accretion Disk Models. II. Diagnostic Tools for X-Ray Observations

    NASA Technical Reports Server (NTRS)

    Garcia, J.; Kallman, T. R.; Mushotzky, R. F.

    2011-01-01

    We present a comprehensive study of the emission spectra from accreting sources. We use our new reflection code to compute the reflected spectra from an accretion disk illuminated by X-rays. This set of models covers different values of ionization parameter, solar iron abundance and photon index for the illuminating spectrum. These models also include the most complete and recent atomic data for the inner-shell of the iron and oxygen isonuclear sequences. We concentrate our analysis to the 2 - 10 keV energy region, and in particular to the iron K-shell emission lines. We show the dependency of the equivalent width (EW) of the Fe Ka with the ionization parameter. The maximum value of the EW is approx. 800 eV for models with log Epsilon approx. 1.5, and decreases monotonically as Epsilon increases. For lower values of Epsilon the Fe K(alpha) EW decreases to a minimum near log Epsilon approx. 0.8. We produce simulated CCD observations based on our reflection models. For low ionized, reflection dominated cases, the 2 -10 keV energy region shows a very broad, curving continuum that cannot be represented by a simple power-law. We show that in addition to the Fe K-shell emission, there are other prominent features such as the Si and S L(alpha) lines, a blend of Ar VIII-XI lines, and the Ca x K(alpha) line. In some cases the S xv blends with the He-like Si RRC producing a broad feature that cannot be reproduced by a simple Gaussian profile. This could be used as a signature of reflection.

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

    NASA Astrophysics Data System (ADS)

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

    2004-07-01

    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.

  4. Evidence of Perturbations on the S_1 Surface of Acetylene from Patterns in Stimulated Emission Pumping Spectra

    NASA Astrophysics Data System (ADS)

    Park, G. Barratt; Baraban, Joshua H.; Steeves, Adamh.; Field, Robert W.

    2011-06-01

    Stimulated Emission Pumping (SEP) spectra from the 3^4 level of S_1 acetylene to the N_B=10 polyad of S_0 contain evidence of an unexpected interference effect. S_0 intrapolyad intensity distributions are as a rule governed solely by the fractionation of the (single) bright state. However, the intensity distribution in the SEP spectrum observed from 3^4 deviates from the expected pattern. Reduced dimension DVR calculations on the S_1 surface predict a three-state interaction involving one of the S_1 interloper bands. According to the calculation, this cis interloper state engenders an indirect coupling between the trans 2^13^16^2 and 3^4 zero order states, causing the eigenstates to lie substantially farther apart than one might expect, and lending intensity to the cis 3^16^1 interloper band that appears between them. These predictions agree quite well with the experimental observations. The intensity distribution in the SEP spectrum observed from 3^4 seems to contain an interfering combination of the bright state patterns seen in the 2^13^2 and the 3^2B^2 spectra. This type of indirect effect can yield much information about state mixing, and is particularly interesting in this case since its effects on the level structure cannot reasonably be accounted for by effective Hamiltonian models that rely solely on polyads.

  5. Origins of PM10 determined by the micro-proton induced X-ray emission spectra of single aerosol particles

    SciTech Connect

    Yue, W.S.; Li, X.L.; Wan, T.M.; Liu, J.F.; Zhang, G.L.; Li, Y.

    2006-06-15

    The micro-proton induced X-ray emission (micro-PIXE) spectrum of a single aerosol particle (SAP) was considered as its fingerprint for tracing its origin. A proton microprobe was used to extract fingerprints of SAPs. Environmental monitoring samples of PM10 were collected from a heavy industrial area of Shanghai and were analyzed by proton microprobe for finding their pollution sources. In order to find the sources of SAPs collected from environmental monitoring sites, a fingerprint database of SAPS collected from various pollution Sources was established. The origins of samples collected through environmental monitoring were identified by comparison of the micro-PIXE spectra of SAPs with those of SAPs in the fingerprint database using a pattern recognition technique. The results of this study show that most of the measured PM10 is derived from metallurgic industry, soil dust, coal combustion, automobile exhaust, and motorcycle exhaust. The study also shows that the proton microprobe is an ideal tool for the analysis of SAPs. The unidentified particles of PM10 are classified into seven classes by hierarchical cluster analysis based on the element peak intensity in the spectra.

  6. Origins of PM10 determined by the micro-proton induced X-ray emission spectra of single aerosol particles.

    PubMed

    Yue, Weisheng; Li, Xiaolin; Wan, Tianmin; Liu, Jiangfeng; Zhang, Guilin; Li, Yan

    2006-06-01

    The micro-proton induced X-ray emission (micro-PIXE) spectrum of a single aerosol particle (SAP) was considered as its fingerprint for tracing its origin. A proton microprobe was used to extract fingerprints of SAPs. Environmental monitoring samples of PM(10) were collected from a heavy industrial area of Shanghai and were analyzed by proton microprobe for finding their pollution sources. In order to find the sources of SAPs collected from environmental monitoring sites, a fingerprint database of SAPs collected from various pollution sources was established. The origins of samples collected through environmental monitoring were identified by comparison of the micro-PIXE spectra of SAPs with those of SAPs in the fingerprint database using a pattern recognition technique. The results of this study show that most of the measured PM(10) is derived from metallurgic industry, soil dust, coal combustion, automobile exhaust, and motorcycle exhaust. The study also shows that the proton microprobe is an ideal tool for the analysis of SAPs. The unidentified particles of PM(10) are classified into seven classes by hierarchical cluster analysis based on the element peak intensity in the spectra. PMID:16808872

  7. Emission lines of [K V] in the optical spectra of gaseous nebulae.

    PubMed

    Keenan, Francis P; Aller, Lawrence H; Espey, Brian R; Exter, Katrina M; Hyung, Siek; Keenan, Michael T C; Pollacco, Don L; Ryans, Robert S I

    2002-04-01

    Recent R-matrix calculations of electron impact excitation rates in K v are used to derive the nebular emission line ratio R = I(4122.6 A)/I(4163.3 A) as a function of electron density (N(e)). This ratio is found to be very sensitive to changes in N(e) over the density range 10(3) to 10(6) cm(-3), but does not vary significantly with electron temperature, and hence in principle should provide an excellent optical N(e) diagnostic for the high-excitation zones of nebulae. The observed value of R for the planetary nebula NGC 7027, measured from a spectrum obtained with the Hamilton Echelle spectrograph on the 3-m Shane Telescope, implies a density in excellent agreement with that derived from [Ne iv], formed in the same region of the nebula as [K v]. This observation provides observational support for the accuracy of the theoretical [K v] line ratios, and hence the atomic data on which they are based. However, the analysis of a high-resolution spectrum of the symbiotic star RR Telescopii, obtained with the University College London Echelle Spectrograph on the 3.9-m Anglo-Australian Telescope, reveals that the [K v] 4122.6 A line in this object is badly blended with Fe ii 4122.6 A. Hence, the [K v] diagnostic may not be used for astrophysical sources that show a strong Fe ii emission line spectrum. PMID:11904366

  8. Emission lines of [K v] in the optical spectra of gaseous nebulae

    PubMed Central

    Keenan, Francis P.; Aller, Lawrence H.; Espey, Brian R.; Exter, Katrina M.; Hyung, Siek; Keenan, Michael T. C.; Pollacco, Don L.; Ryans, Robert S. I.

    2002-01-01

    Recent R-matrix calculations of electron impact excitation rates in K v are used to derive the nebular emission line ratio R = I(4122.6 ?)/I(4163.3 ?) as a function of electron density (Ne). This ratio is found to be very sensitive to changes in Ne over the density range 103 to 106 cm?3, but does not vary significantly with electron temperature, and hence in principle should provide an excellent optical Ne diagnostic for the high-excitation zones of nebulae. The observed value of R for the planetary nebula NGC 7027, measured from a spectrum obtained with the Hamilton Echelle spectrograph on the 3-m Shane Telescope, implies a density in excellent agreement with that derived from [Ne iv], formed in the same region of the nebula as [K v]. This observation provides observational support for the accuracy of the theoretical [K v] line ratios, and hence the atomic data on which they are based. However, the analysis of a high-resolution spectrum of the symbiotic star RR Telescopii, obtained with the University College London Echelle Spectrograph on the 3.9-m Anglo–Australian Telescope, reveals that the [K v] 4122.6 ? line in this object is badly blended with Fe ii 4122.6 ?. Hence, the [K v] diagnostic may not be used for astrophysical sources that show a strong Fe ii emission line spectrum. PMID:11904366

  9. Emission spectra from ZnS:Mn due to low velocity impacts

    NASA Astrophysics Data System (ADS)

    Hollerman, W. A.; Goedeke, S. M.; Bergeron, N. P.; Moore, R. J.; Allison, S. W.; Lewis, L. A.

    2005-09-01

    Triboluminescence (TL) is the emission of light due to crystal fracture and has been known for centuries. One of the most common examples of TL is the flash created from chewing wintergreen Lifesavers. Since 2003, the authors have been measuring triboluminescent properties of phosphors, of which zinc sulfide doped with manganese (ZnS:Mn) is an example. Preliminary results indicate that impact velocities greater than 0.5 m/s produce measurable TL from ZnS:Mn. To extend this research, the investigation of the emission spectrum was chosen. This differs from using filtered photodetectors in that the spectral composition of fluorescence can be ascertained. Previous research has utilized a variety of schemes that include scratching, crushing, and grinding to generate TL. In our case, the material is activated by a short duration interaction of a dropped mass and a small number of luminescence centers. This research provides a basis for the characterization and selection of materials for future spacecraft impact detection schemes.

  10. INTENSITY ENHANCEMENT OF O VI ULTRAVIOLET EMISSION LINES IN SOLAR SPECTRA DUE TO OPACITY

    SciTech Connect

    Keenan, F. P.; Mathioudakis, M.; Doyle, J. G.; Madjarska, M. S.; Rose, S. J.; Bowler, L. A.; Britton, J.; McCrink, L.

    2014-04-01

    Opacity is a property of many plasmas. It is normally expected that if an emission line in a plasma becomes optically thick, then its intensity ratio to that of another transition that remains optically thin should decrease. However, radiative transfer calculations undertaken both by ourselves and others predict that under certain conditions the intensity ratio of an optically thick to an optically thin line can show an increase over the optically thin value, indicating an enhancement in the former. These conditions include the geometry of the emitting plasma and its orientation to the observer. A similar effect can take place between lines of differing optical depths. While previous observational studies have focused on stellar point sources, here we investigate the spatially resolved solar atmosphere using measurements of the I(1032 Å)/I(1038 Å) intensity ratio of O VI in several regions obtained with the Solar Ultraviolet Measurements of Emitted Radiation instrument on board the Solar and Heliospheric Observatory satellite. We find several I(1032 Å)/I(1038 Å) ratios observed on the disk to be significantly larger than the optically thin value of 2.0, providing the first detection (to our knowledge) of intensity enhancement in the ratio arising from opacity effects in the solar atmosphere. The agreement between observation and theory is excellent and confirms that the O VI emission originates from a slab-like geometry in the solar atmosphere, rather than from cylindrical structures.

  11. Superresolution and other mathematical techniques for quantitative analysis of infrared absorption and emission spectra of gases

    NASA Astrophysics Data System (ADS)

    Davies, Nicholas M.; Lettington, Alan H.; Hilton, Moira

    1997-05-01

    Fourier transform IR (FTIR) spectroscopy has become a powerful analytical tool for the detection and measurement of atmospheric pollutant gases. This work describes the application of concentration analysis techniques to data recorded with a versatile FTIR spectroscopy system, developed at the University of Reading PHysics Department. Spectra were recorded at three separate sites, each possessing a distinct source of atmospheric pollution gases. The two sites monitored in the active mode were a traffic congested town center at rush hour and a dairy farm cow shed. The site monitored passively contained three 5 m high methane burners. The analysis techniques have been designed to provide rapid and accurate analysis of the spectrometer data, without the need for high computing power, thus making analysis possible in the field using a laptop PC. In an attempt to enhance the resolution of the spectral data, and therefore resolve overlapping spectral lines, a super- resolution algorithm has been tested on part of the recorded data. The results of applying the algorithm has been tested on part of the recorded data. The results of applying the algorithm, predominantly an image processing technique, are shown and improvements to the algorithm are discussed. Results from the urban and agricultural sites show that CO, CH4, and NH3 can be measured to a ppm level with a maximum uncertainly of 8 percent.

  12. Ultraviolet emission lines of Si II in cool star and solar spectra

    E-print Network

    Laha, Sibasish; ferland, Gary J; Ramsbottom, Catherine A; Aggarwal, Kanti M; Ayres, Thomas R; Chatzikos, Marios; van Hoof, Peter A M; Williams, Robin J R

    2015-01-01

    Recent atomic physics calculations for Si II are employed within the Cloudy modelling code to analyse Hubble Space Telescope (HST) STIS ultraviolet spectra of three cool stars, Beta-Geminorum, Alpha-Centauri A and B, as well as previously published HST/GHRS observations of Alpha-Tau, plus solar quiet Sun data from the High Resolution Telescope and Spectrograph. Discrepancies found previously between theory and observation for line intensity ratios involving the 3s$^{2}$3p $^{2}$P$_{J}$--3s3p$^{2}$ $^{4}$P$_{J^{\\prime}}$ intercombination multiplet of Si II at 2335 Angs are significantly reduced, as are those for ratios containing the 3s$^{2}$3p $^{2}$P$_{J}$--3s3p$^{2}$ $^{2}$D$_{J^{\\prime}}$ transitions at 1816 Angs. This is primarily due to the effect of the new Si II transition probabilities. However, these atomic data are not only very different from previous calculations, but also show large disagreements with measurements, specifically those of Calamai et. al. (1993) for the intercombination lines. New m...

  13. Ultraviolet emission lines of Si II in cool star and solar spectra

    NASA Astrophysics Data System (ADS)

    Laha, Sibasish; Keenan, Francis P.; Ferland, Gary J.; Ramsbottom, Catherine A.; Aggarwal, Kanti M.; Ayres, Thomas R.; Chatzikos, Marios; van Hoof, Peter A. M.; Williams, Robin J. R.

    2016-01-01

    Recent atomic physics calculations for Si II are employed within the CLOUDY modelling code to analyse Hubble Space Telescope (HST) STIS ultraviolet spectra of three cool stars, ? Geminorum, ? Centauri A and B, as well as previously published HST/GHRS observations of ? Tau, plus solar quiet Sun data from the High Resolution Telescope and Spectrograph. Discrepancies found previously between theory and observation for line intensity ratios involving the 3s23p 2PJ-3s3p2 4P_{J^' }} intercombination multiplet of Si II at ˜ 2335 Å are significantly reduced, as are those for ratios containing the 3s23p 2PJ-3s3p2 2D_{J^' }} transitions at ˜1816 Å. This is primarily due to the effect of the new Si II transition probabilities. However, these atomic data are not only very different from previous calculations, but also show large disagreements with measurements, specifically those of Calamai et al. for the intercombination lines. New measurements of transition probabilities for Si II are hence urgently required to confirm (or otherwise) the accuracy of the recently calculated values. If the new calculations are confirmed, then a long-standing discrepancy between theory and observation will have finally been resolved. However, if the older measurements are found to be correct, then the agreement between theory and observation is simply a coincidence and the existing discrepancies remain.

  14. Stratospheric minor constituent distributions from far-infrared thermal emission spectra

    NASA Astrophysics Data System (ADS)

    Abbas, Mian M.; Traub, Wesley A.

    1992-11-01

    We retrieve mixing ratio profiles of O3, H2(O-16), H2(O-17), H2(O-18), HF, and HCl from far-infrared thermal emission observations of the limb in the 80-220 cm/sec 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 Traub et al. (1982, 1991); in the present paper we use an alternative method of calibration and analysis, given by Abbas 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 H2(O-17) and H2(O-18) obtained in this study indicate no isotopic enhancement or depletion with a standard deviation of about 20 percent.

  15. Anomalous Series of Bands in the Edge Emission Spectra of CdS(?)

    NASA Astrophysics Data System (ADS)

    Morozova, N. K.; Kanakhin, A. A.; Galstyan, V. G.; Shnitnikov, A. S.

    2015-02-01

    The region of the edge emission spectrum of CdS(O) single crystals with cadmium excess is examined. An anomalous series of equidistant bands with leading line at 514 nm and phonon replicas has been revealed. These bands grow in intensity with increase of the excitation density up to 1026-1027 cm-3?s-1 at 80 K, and the leading line of the series is observed even at 300 K. It is shown that luminescence is conditioned by the exciton spectrum in perfect bulk single-crystals of CdO. Some characteristics of this spectrum are presented, in particular, the dependence on temperature, excitation intensity, composition and size of the crystals, and the LO interaction. The results experimentally confirm the theoretically calculated magnitude of the direct band gap of CdO.

  16. Ion temperatures in HIP-1 and SUMMA from charge-exchange neutral optical emission spectra

    NASA Technical Reports Server (NTRS)

    Patch, R. W.; Lauver, M. R.

    1976-01-01

    Ion temperatures were obtained from observations of the H sub alpha, D sub alpha, and He 587.6 nm lines emitted from hydrogen, deuterium, and helium plasmas in the SUMMA and HIP-1 mirror devices at Lewis Research Center. Steady state discharges were formed by applying a radially inward dc electric field between cylindrical or annular anodes and hollow cathodes located at the peaks of the mirrors. The ion temperatures were found from the Doppler broadening of the charge-exchange components of spectral lines. A statistical method was developed for obtaining scaling relations of ion temperature as a function of current, voltage, and magnetic flux density. Derivations are given that take into account triangular monochromator slit functions, loss cones, and superimposed charge-exchange processes. In addition, the Doppler broadening was found to be sensitive to the influence of drift on charge-exchange cross section. The effects of finite ion-cyclotron radius, cascading, and delayed emission are reviewed.

  17. Thermal Emission Spectra of Silica-coated Basalt and Considerations for Martian Surface Mineralogy

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    Among the most important discoveries made during the Mars Global Surveyor (MGS) mission was that the rocky materials of Mars are broadly divisible into two distinct rock types. The geological significance of this finding is dependent on the mineralogy of these rock types as well as their geographic and stratigraphic positions. Much work has yet to be done to understand these relationships and the small-scale variability of these units. For now, it is worth considering various scenarios that could have resulted in Mars global-scale mineralogical dichotomy. Such work will make clearer what must be looked for in Thermal Emission Spectrometer (TES) and Thermal Imaging Spectrometer (THEMIS) data, what to test with other data sets, and what geological processes can be considered or ruled out as we advance with interpreting Martian geologic history. Here, we suggest that exogenic coatings of secondary silica on basaltic rocks may provide a plausible explanation for the newly discovered distribution of rock types.

  18. Observation of soft X-ray spectra from a Seyfert 1 and a narrow emission-line galaxy

    NASA Technical Reports Server (NTRS)

    Singh, K. P.; Garmire, G. P.; Nousek, J.

    1985-01-01

    The 0.2-40 keV X-ray spectra of the Seyfert 1 galaxy Mrk 509 and the narrow emission-line galaxy NGC 2992 are analyzed. The results suggest the presence of a steep soft X-ray component in Mrk 509 in addition to the well-known Gamma = 1.7 component found in other active galactic nuclei in the 2-40 keV energy range. The soft X-ray component is interpreted as due to thermal emission from a hot gas, probably associated with the highly ionized gas observed to be outflowing from the galaxy. The X-ray spectrum of NGC 2992 does not show any steepening in the soft X-ray band and is consistent with a single power law (Gamma = 1.78) with very low absorbing column density of 4 x 10 to the 21st/sq cm. A model with partial covering of the nuclear X-ray source is preferred, however, to a simple model with a single power law and absorption.

  19. Ultraviolet Emission-Line Correlations in Hubble/COS Spectra of Active Galactic Nuclei: Single-Epoch Black Hole Masses

    E-print Network

    Tilton, Evan M

    2013-01-01

    Effective methods of measuring supermassive black hole masses in active galactic nuclei (AGN) are of critical importance to studies of galaxy evolution. While there has been much success obtaining masses through reverberation mapping, the extensive observing time required by this method has limited the practicality of applying it to large samples at a variety of redshifts. This limitation highlights the need to estimate these masses using single-epoch spectroscopy of ultraviolet emission lines. We use ultraviolet spectra of 44 AGN from HST/COS, IUE, and FUSE of the CIV 1549, OVI 1035, OIII] 1664, HeII 1640, CII 1335, and MgII 2800 emission lines and explore their potential as tracers of the broad-line region and supermassive black hole mass. The higher S/N and better spectral resolution of the Cosmic Origins Spectrograph on Hubble Space Telescope resolves AGN intrinsic absorption and produces more accurate line widths. From these, we test the viability of mass-scaling relationships based on line widths and lu...

  20. Fluorescence excitation and emission spectra of ALA-induced protoporphyrin IX in normal and tumoral tissue of the human bladder

    NASA Astrophysics Data System (ADS)

    Forrer, Martin; Glanzmann, Thomas M.; Mizeret, Jerome C.; Braichotte, Daniel; Wagnieres, Georges A.; van den Bergh, Hubert; Jichlinski, Patrice; Leisinger, Hans-Juerg

    1995-01-01

    In vivo spectrofluorometric analysis represents a tool to obtain information about fluorophore distribution in tissue. Based on a Peltier-cooled CCD we designed a fluorescence excitation and emission spectrograph which allows to obtain tissue spectra endoscopically and in a clinical environment. Clinical studies were performed on patients with positive cytology or tumor recurrence in the urinary bladder. Patients received a 50 ml instillation of 3% ALA solution at pH 5.5 during 3 to 4 hours and underwent a normal white light cystoscopic examination together with light induced fluorescence photodetection at 5 to 8 hours after the beginning of the instillation. Local fluorescence measurements with a single fiber were performed before photodetection. These showed fluorescence ratios between tumor and normal tissue of 1.5 to 20 with the strongest ratios for exophytic papillary tumors. Fluorescence excitation between 380 nm and 450 nm revealed that the higher Protoporphyrin IX (PPIX) signal on tumor tissue is accompanied by a decrease of the autofluorescence at the emission wavelength of 500 nm.

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

    SciTech Connect

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

    2008-05-05

    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.

  2. Single Nanoparticle Mass Spectrometry as a High Temperature Kinetics Tool: Sublimation, Oxidation, and Emission Spectra of Hot Carbon Nanoparticles.

    PubMed

    Howder, Collin R; Long, Bryan A; Gerlich, Dieter; Alley, Rex N; Anderson, Scott L

    2015-12-17

    In single nanoparticle mass spectrometry, individual charged nanoparticles (NPs) are trapped in a quadrupole ion trap and detected optically, allowing their mass, charge, and optical properties to be monitored continuously. Previous experiments of this type probed NPs that were either fluorescent or large enough to detect by light scattering. Alternatively, small NPs can be heated to temperatures where thermally excited emission is strong enough to allow detection, and this approach should provide a new tool for measurements of sublimation and surface reaction kinetics of materials at high temperatures. As an initial test, we report a study of carbon NPs in the 20-50 nm range, heated by 10.6 ?m, 532 nm, or 445 nm lasers. The kinetics for sublimation and oxidation of individual carbon NPs were studied, and a model is presented for the factors that control the NP temperature, including laser heating, and cooling by sublimation, buffer gas collisions, and radiation. The estimated NP temperatures were in the 1700-2000 K range, and the NP absorption cross sections ranged from ?0.8 to 0.2% of the geometric cross sections for 532 nm and 10.6 ?m excitation, respectively. Emission spectra of single NPs and small NP ensembles show a feature in the IR that appears to be the high energy tail of the thermal (blackbody-like) emission expected from hot particles but also a discrete feature peaking around 750 nm. Both the IR tail and 750 nm peak are observed for all particles and for both IR and visible laser excitation. No significant difference was observed between graphite and amorphous carbon NPs. PMID:26513667

  3. Detection of Broad H? Emission Lines in the Late-time Spectra of a Hydrogen-poor Superluminous Supernova

    NASA Astrophysics Data System (ADS)

    Yan, Lin; Quimby, R.; Ofek, E.; Gal-Yam, A.; Mazzali, P.; Perley, D.; Vreeswijk, P. M.; Leloudas, G.; de Cia, A.; Masci, F.; Cenko, S. B.; Cao, Y.; Kulkarni, S. R.; Nugent, P. E.; Rebbapragada, Umaa D.; Wo?niak, P. R.; Yaron, O.

    2015-12-01

    iPTF13ehe is a hydrogen-poor superluminous supernova (SLSN) at z = 0.3434, with a slow-evolving light curve and spectral features similar to SN2007bi. It rises in 83–148 days to reach a peak bolometric luminosity of ?1.3 × 1044 erg s?1, then decays slowly at 0.015 mag day?1. The measured ejecta velocity is ? 13,000 km s?1. The inferred explosion characteristics, such as the ejecta mass (70–220 M?), and the total radiative and kinetic energy (Erad ? 1051 erg, Ekin ? 2 × 1053 erg), are typical of slow-evolving H-poor SLSN events. However, the late-time spectrum taken at +251 days (rest, post-peak) reveals a Balmer H? emission feature with broad and narrow components, which has never been detected before among other H-poor SLSNe. The broad component has a velocity width of ?4500 km s?1 and a ?300 km s?1 blueward shift relative to the narrow component. We interpret this broad H? emission with a luminosity of ?2 × 1041 erg s?1 as resulting from the interaction between the supernova ejecta and a discrete H-rich shell, located at a distance of ?4 × 1016 cm from the explosion site. This interaction causes the rest-frame r-band LC to brighten at late times. The fact that the late-time spectra are not completely absorbed by the shock-ionized H-shell implies that its Thomson scattering optical depth is likely ?1, thus setting upper limits on the shell mass ?30 M?. Of the existing models, a Pulsational Pair Instability supernova model can naturally explain the observed 30 M? H-shell, ejected from a progenitor star with an initial mass of (95–150) M? about 40 years ago. We estimate that at least ?15% of all SLSNe-I may have late-time Balmer emission lines.

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  5. Characterisation of NEXT-DEMO using xenon K$_{\\alpha}$ X-rays

    E-print Network

    Lorca, D; Laing, A; Ferrario, P; Gómez-Cadenas, J J; Álvarez, V; Borges, F I G; Camargo, M; Cárcel, S; Cebrián, S; Cervera, A; Conde, C A N; Dafni, T; Díaz, J; Esteve, R; Fernandes, L M P; Ferreira, A L; Freitas, E D C; Gehman, V M; Goldschmidt, A; Gómez, H; González-Díaz, D; Gutiérrez, R M; Hauptman, J; Morata, J A Hernando; Herrera, D C; Irastorza, I G; Labarga, L; Liubarsky, I; Losada, M; Luzón, G; Marí, A; Martínez-Lema, G; Martínez, A; Miller, T; Monrabal, F; Monserrate, M; Monteiro, C M B; Mora, F J; Moutinho, L M; Vidal, J Muñoz; Nebot-Guinot, M; Nygren, D; Oliveira, C A B; Pérez, J; Aparicio, J L Pérez; Renner, J; Ripoll, L; Rodríguez, A; Rodríguez, J; Santos, F P; Santos, J M F dos; Seguí, L; Serra, L; Shuman, D; Simón, A; Sofka, C; Sorel, M; Toledo, J F; Torrent, J; Tsamalaidze, Z; Veloso, J F C A; Webb, R; White, J T; Yahlali, N

    2014-01-01

    The NEXT experiment aims to observe the neutrinoless double beta decay of $^{136}$Xe in a high pressure gas TPC using electroluminescence (EL) to amplify the signal from ionization. Understanding the response of the detector is imperative in achieving a consistent and well understood energy measurement. The abundance of xenon k-shell x-ray emission during data taking has been identified as a multitool for the characterisation of the fundamental parameters of the gas as well as the equalisation of the response of the detector. The NEXT-DEMO prototype is a ~1.5 kg volume TPC filled with natural xenon. It employs an array of 19 PMTs as an energy plane and of 256 SiPMs as a tracking plane with the TPC light tube and SiPM surfaces being coated with tetraphenyl butadiene (TPB) which acts as a wavelength shifter for the VUV scintillation light produced by xenon. This paper presents the measurement of the properties of the drift of electrons in the TPC, the effects of the EL production region, and the extraction of p...

  6. Electron-Electron Bremsstrahlung Emission and the Inference of Electron Flux Spectra in Solar Flares

    E-print Network

    Eduard P. Kontar; A. Gordon Emslie; Anna Maria Massone; Michele Piana; John C. Brown; Marco Prato

    2007-07-28

    Although both electron-ion and electron-electron bremsstrahlung contribute to the hard X-ray emission from solar flares, the latter is normally ignored. Such an omission is not justified at electron (and photon) energies above $\\sim 300$ keV, and inclusion of the additional electron-electron bremsstrahlung in general makes the electron spectrum required to produce a given hard X-ray spectrum steeper at high energies. Unlike electron-ion bremsstrahlung, electron-electron bremsstrahlung cannot produce photons of all energies up to the maximum electron energy involved. The maximum possible photon energy depends on the angle between the direction of the emitting electron and the emitted photon, and this suggests a diagnostic for an upper cutoff energy and/or for the degree of beaming of the accelerated electrons. We analyze the large event of January 17, 2005 observed by RHESSI and show that the upward break around 400 keV in the observed hard X-ray spectrum is naturally accounted for by the inclusion of electron-electron bremsstrahlung. Indeed, the mean source electron spectrum recovered through a regularized inversion of the hard X-ray spectrum, using a cross-section that includes both electron-ion and electron-electron terms, has a relatively constant spectral index $\\delta$ over the range from electron kinetic energy $E = 200$ keV to $E = 1$ MeV. However, the level of detail discernible in the recovered electron spectrum is not sufficient to determine whether or not any upper cutoff energy exists.

  7. [Two-temperature diagnostic studies by emission spectra for nonequilibrium Ti-H plasma].

    PubMed

    Deng, Chun-feng; Lu, Biao; Wu, Chun-lei; Wang, Yi-fu; Wen, Zhong-wei

    2014-12-01

    Using the T-H solid solution made by titanium absorbed hydrogen as the cathode, the Ti-H plasma produced by the pulsed vacuum are ion source was nonequilibrium: it contained both the component of titanium and hydrogen; there existed gradient in the radiaL, the horizontal and the time. As a result, it could not be described by a single temperature. The present paper assumed that the subsystem consisting of electrons and the subsystem consisting of other heavy particles reached equilibrium respectively, meaning that the Ti-H plasma was described by the two temperatures as electron temperature and heavy ion temperature, it was non-equilibrium two-temperature plasma Using Culdberg-Waage dissociation equation to describe the molecular dissociation process in the system, using Saha ionization equation to describe the atomic ionization process, combining plasma's charge quasi-neutral condition and introducing atomic emission spectroscopy as a plasma diagnostic method which would not interfere the plasma at the same time; the temperature and the particle number density of the Ti-H plasma were diagnosed. Using MATLAB as a tool, both the titanium atoms and monovalent titanium ions' ionization were considered, and the calculated results showed that with the electtron density determined by the Stark broadening of spectral lines in advance, except the heavy particle temperature and the hydrogen number density, the Ti-H plasma's parameters could be diagnosed fairly accurately; the accuracy of the electron density values had a great effect on the calculation results; if the heavy particle temperature could be determined in advance, the temperature and the particle number density of the Ti-H plasma could be accurately analyzed quantitatively. PMID:25881442

  8. Complex X-ray Absorption and the Fe K(alpha) Profile in NGC 3516

    NASA Technical Reports Server (NTRS)

    Turner, T. J.; Kraemer, S. B.; George, I. M.; Reeves, J. N.; Botorff, M. C.

    2004-01-01

    We present data from simultaneous Chandra, XMM-Newton and BeppoSAX observations of the Seyfert 1 galaxy NGC 3516, taken during 2001 April and November. We have investigated the nature of the very flat observed X-ray spectrum. Chandra grating data show the presence of X-ray absorption lines, revealing two distinct components of the absorbing gas, one which is consistent with our previous model of the UV/X-ray absorber while the other, which is outflowing at a velocity of approximately 1100 kilometers per second, has a larger column density and is much more highly ionized. The broad-band spectral characteristics of the X-ray continuum observed with XMM during 2001 April, reveal the presence of a third layer of absorption consisting of a very large column (approximately 2.5 x 10(exp 23) per square centimeter) of highly ionized gas with a covering fraction approximately 50%. This low covering fraction suggests that the absorber lies within a few 1t-days of the X-ray source and/or is filamentary in structure. Interestingly, these absorbers are not in thermal equilibrium with one another. The two new components are too highly ionized to be radiatively accelerated, which we suggest is evidence for a hydromagnetic origin for the outflow. Applying our model to the November dataset, we can account for the spectral variability primarily by a drop in the ionization states of the absorbers, as expected by the change in the continuum flux. When this complex absorption is accounted for we find the underlying continuum to be typical of Seyfert 1 galaxies. The spectral curvature attributed to the high column absorber, in turn, reduces estimates of the flux and extent of any broad Fe emission line from the accretion disk.

  9. ULTRAVIOLET EMISSION-LINE CORRELATIONS IN HST/COS SPECTRA OF ACTIVE GALACTIC NUCLEI: SINGLE-EPOCH BLACK HOLE MASSES

    SciTech Connect

    Tilton, Evan M.; Shull, J. Michael E-mail: michael.shull@colorado.edu

    2013-09-01

    Effective methods of measuring supermassive black hole masses in active galactic nuclei (AGNs) are of critical importance to studies of galaxy evolution. While there has been much success in obtaining masses through reverberation mapping, the extensive observing time required by this method has limited the practicality of applying it to large samples at a variety of redshifts. This limitation highlights the need to estimate these masses using single-epoch spectroscopy of ultraviolet (UV) emission lines. We use UV spectra of 44 AGNs from HST/COS, the International Ultraviolet Explorer, and the Far Ultraviolet Spectroscopic Explorer of the C IV {lambda}1549, O VI {lambda}1035, O III] {lambda}1664, He II {lambda}1640, C II {lambda}1335, and Mg II {lambda}2800 emission lines and explore their potential as tracers of the broad-line region and supermassive black hole mass. The higher signal-to-noise ratio and better spectral resolution of the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST) resolve AGN intrinsic absorption and produce more accurate line widths. From these, we test the viability of mass-scaling relationships based on line widths and luminosities and carry out a principal component analysis based on line luminosities, widths, skewness, and kurtosis. At L{sub 1450} {<=} 10{sup 45} erg s{sup -1}, the UV line luminosities correlate well with H{beta}, as does the 1450 A continuum luminosity. We find that C IV, O VI, and Mg II can be used as reasonably accurate estimators of AGN black hole masses, while He II and C II are uncorrelated.

  10. Vibration-rotation emission spectra and combined isotopomer analyses for the coinage metal hydrides: CuH & CuD, AgH & AgD, and AuH

    E-print Network

    Le Roy, Robert J.

    emission studies of the spectra of the coinage metal hydrides. Since the first laboratory study of CuVibration-rotation emission spectra and combined isotopomer analyses for the coinage metal hydrides: CuH & CuD, AgH & AgD, and AuH & AuD Jenning Y. Seto, Zulfikar Morbi,a) Frank Charron, Sang K. Lee

  11. Research as a guide for curriculum development: An example from introductory spectroscopy. II. Addressing student difficulties with atomic emission spectra

    NASA Astrophysics Data System (ADS)

    Ivanjek, L.; Shaffer, P. S.; McDermott, L. C.; Planinic, M.; Veza, D.

    2015-02-01

    This is the second of two closely related articles (Paper I and Paper II) that together illustrate how research in physics education has helped guide the design of instruction that has proved effective in improving student understanding of atomic spectroscopy. Most of the more than 1000 students who participated in this four-year investigation were science majors enrolled in the introductory calculus-based physics course at the University of Washington (UW) in Seattle, WA, USA. The others included graduate and undergraduate teaching assistants at UW and physics majors in introductory and advanced physics courses at the University of Zagreb, Zagreb, Croatia. About half of the latter group were preservice high school physics teachers. Paper I describes how several conceptual and reasoning difficulties were identified among university students as they tried to relate a discrete line spectrum to the energy levels of atoms in a light source. This second article (Paper II) illustrates how findings from this research informed the development of a tutorial that led to improvement in student understanding of atomic emission spectra.

  12. Research as a guide for curriculum development: An example from introductory spectroscopy. I. Identifying student difficulties with atomic emission spectra

    NASA Astrophysics Data System (ADS)

    Ivanjek, L.; Shaffer, P. S.; McDermott, L. C.; Planinic, M.; Veza, D.

    2015-01-01

    This is the first of two closely related articles (Paper I and Paper II) that together illustrate how research in physics education has helped guide the design of instruction that has proved effective in improving student understanding of atomic spectroscopy. Most of the more than 1000 students who participated in this four-year investigation were science majors enrolled in the introductory calculus-based physics course at the University of Washington (UW) in Seattle, WA, USA. The others included graduate and undergraduate teaching assistants at UW and physics majors in introductory and advanced physics courses at the University of Zagreb, Zagreb, Croatia. About half of the latter group were preservice high school physics teachers. This article (Paper I) describes how several serious conceptual and reasoning difficulties were identified among students as they tried to relate a discrete line spectrum to the energy levels of atoms in a light source. Paper II illustrates how findings from this research informed the development of a tutorial that led to significant improvement in student understanding of atomic emission spectra.

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

    SciTech Connect

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

    2006-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

    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

    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.

  15. Measurements of the Temperature of Subsonic CO{sub 2} Induction Plasma Flows by Analyzing Their Emission Spectra

    SciTech Connect

    Bykova, N.G.; Kuznetsova, L.A.

    2004-11-15

    Results are presented from measurements of the temperature characteristics of subsonic CO{sub 2} plasma flows generated by a 100-kW induction plasmatron at the Institute for Problems of Mechanics, Russian Academy of Sciences. The atomic excitation temperature T{sub a} and the population temperature T{sub e} of the electronic states of C{sub 2} molecules (both averaged over the jet diameter) were measured from the absolute intensities of the atomic spectral lines and the spectrum of C{sub 2} molecules in different generation regimes at gas pressures of 25-140 hPa and anode supply powers of 29-72 kW. The longitudinal and radial profiles of the temperatures were determined for some of these regimes and compared to those obtained from numerical calculations of equilibrium induction plasma flows in the discharge channel. For some generation regimes, the dependences of the averaged (over the line of sight) rotational and vibrational temperatures (T{sub r} and T{sub v} ) on the discharge parameters, as well as the radial profiles of these temperatures, were determined from the best fit of the measured and calculated spectra of C{sub 2} molecules (Swan bands). The self-absorption of molecular emission was observed at sufficiently high temperatures and gas pressures, and its influence on the measured values of the molecular temperatures T{sub e} , T{sub v} , and T{sub r} was examined.

  16. A disk wind interpretation of the strong Fe K{\\alpha} features in 1H 0707-495

    E-print Network

    Hagino, Kouichi; Done, Chris; Tomaru, Ryota; Watanabe, Shin; Takahashi, Tadayuki

    2015-01-01

    1H 0707-495 is the most convincing example of a supermassive black hole with an X-ray spectrum being dominated by extremely smeared, relativistic reflection. However, here we show that the iron features in its 2--10 keV spectrum are rather similar to the archetypal wind dominated source, PDS 456. We fit all the 2--10 keV spectra from 1H 0707-495 using the same wind model as used for PDS 456, but viewed at higher inclination so that the iron absorption line is broader but not so blueshifted. This gives a good overall fit to the data from 1H 0707-495, and an extrapolation of this model to higher energies also gives a good match to the NuSTAR data. Small remaining residuals may indicate that the emission from the wind is stronger than in PDS 456, consistent with the wider angle wind expected from a continuum driven wind from the super-Eddington mass accretion rate in 1H 0707-495. We suggest that the spectrum of 1H 0707-495 is sculpted more by absorption in a wind than by extreme relativistic effects in strong gr...

  17. Complex organic matter in space: about the chemical composition of carriers of the Unidentified Infrared Bands (UIBs) and protoplanetary emission spectra recorded from certain astrophysical objects.

    PubMed

    Cataldo, Franco; Keheyan, Yeghis; Heymann, Dieter

    2004-02-01

    In this communication we present the basic concept that the pure PAHs (Polycyclic Aromatic Hydrocarbons) can be considered only the ideal carriers of the UIBs (Unidentified Infrared Bands), the emission spectra coming from a large variety of astronomical objects. Instead we have proposed that the carriers of UIBs and of protoplanetary nebulae (PPNe) emission spectra are much more complex molecular mixtures possessing also complex chemical structures comparable to certain petroleum fractions obtained from the petroleum refining processes. The demonstration of our proposal is based on the comparison between the emission spectra recorded from the protoplanetary nebulae (PPNe) IRAS 22272+ 5435 and the infrared absorption spectra of certain 'heavy' petroleum fractions. It is shown that the best match with the reference spectrum is achieved by highly aromatic petroleum fractions. It is shown that the selected petroleum fractions used in the present study are able to match the band pattern of anthracite coal. Coal has been proposed previously as a model for the PPNe and UIBs but presents some drawbacks which could be overcome by adopting the petroleum fractions as model for PPNe and UIBs in place of coal. A brief discussion on the formation of the petroleum-like fractions in PPNe objects is included. PMID:14979641

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

    NASA Astrophysics Data System (ADS)

    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.; Jørgensen, U. G.; Liebig, C.; Nikolov, N.; Ricci, D.; Schäfer, S.; Schönebeck, F.; Skottfelt, J.; Wertz, O.; Alsubai, K. A.; Bozza, V.; Browne, P.; Dodds, P.; Gu, S.-H.; Harpsøe, 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

    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.

  19. Updated summary of measurements and calculations of neutron and gamma-ray emission spectra from spheres pusled with 14-MeV neutrons: Revision 1

    SciTech Connect

    Hansen, L.F.; Goldberg, E.; Howerton, R.J.; Komoto, T.T.; Pohl, B.A.

    1989-01-19

    New measurements of the neutron and gamma-ray emission spectra from materials of interest to thermonuclear reactors with a 14 MeV neutron source were done during 1986 and 1987. These measurements characterized by better resolution than those reported in the Summary published in 1982, were performed using the pulsed sphere and time-of-flight techniques. The detector used in these measurements was a NE-213 cylinder, 5.08 cm in diameter by 5.08 cm thick. The new measurements include the following materials: Be, C, N, H/sub 2/O, C/sub 2/F/sub 4/ (teflon), Al, Si, Ti, Fe, Cu, Ta, W, Au, Pb, /sup 232/Th, and /sup 238/U. For all these materials, both the neutron and gamma emission spectra were measured. A complete tabulation of all the measurements done under the Pulse Sphere Program is presented. 37 refs., 1 tab.

  20. Emission spectra of the cations of 1,3- and 1,4-dibromotetrafluorobenzene and of 1,3,5-tribromotrifluorobenzene in the gaseous phase

    USGS Publications Warehouse

    Maier, John Paul; Marthaler, O.; Mohraz, Manijeh; Shiley, R.H.

    1980-01-01

    A search was made for radiative decay of electronically excited cations of 24 bromobenzenes and of their fluoro-substituted derivatives in the gaseous phase. The only emission spectra detected were for the cations of 1,3- and 1,4-dibromotetrafluorobenzene and of 1,3,5-tribromotrifluorobenzene. The band systems, which are found between 670 and 830 nm, are assigned to the B(??-1) ??? A(??-1), X(??-1) electronic transitions of these cations. The assignments are based on the Ne(I) photoelectron spectra which are also presented for some of the studied species. The interpretation for the absence of detectable emission is that the nature of the B cationic states is ??-1, except in the case of 1,3- and 1,4-dibromobenzene cations for which B states are still formed by ??-1 processes. Possible reasons for these observations are discussed. The symmetries of the lowest three electronic states of the studied cations are given. ?? 1980.

  1. The Early X-ray Emission From V382 Velorum (=Nove Vel 1999): An Internal Shock Model

    NASA Technical Reports Server (NTRS)

    Mukai, Koji; Ishida, Manabu

    2000-01-01

    We present the results of ASCA and RXTE observations of the early X-ray emission from the classical nova V382 Velorum. Its ASCA spectrum was hard (kT approximately 10 KeV) with a strong (10(exp 13)/sq cm) intrinsic absorption. In the subsequent RXTE data, the spectra became softer both due to a declining temperature and a diminishing column. We argue that this places the X-ray emission interior to the outermost ejecta produced by V382 Vel in 1999, and therefore must have been the result of a shock internal to the nova ejecta. The weakness of the Fe K.alpha lines probably indicates that the X-ray emitting plasmas are not in ionization equilibrium.

  2. Characterization of K{alpha} spectral profiles for vanadium, component redetermination for scandium, titanium, chromium, and manganese, and development of satellite structure for Z=21 to Z=25

    SciTech Connect

    Chantler, C. T.; Kinnane, M. N.; Su, C.-H.; Kimpton, J. A.

    2006-01-15

    In most high-accuracy x-ray experiments, characteristic radiation is used to determine calibration energies or wavelengths. This paper presents experimental results for vanadium K{alpha}, and component refitting for scandium, titanium, chromium, and manganese, addressing a critical limitation on the current use of this approach. The influence of spectrometer broadening upon the registration of these calibration profiles is quantitatively discussed and determined. The analysis permits such calibration with insignificant loss of accuracy compared to the reference uncertainty, down to a one part per million level. In the process we reveal key empirical structural trends in K{alpha} spectral profiles from Z=21 to Z=25 which originate from detailed physical processes which are neither well understood nor well evaluated theoretically.

  3. Neutron Emission Spectra of 104,105,106,108,110Pd Isotopes for (p,xn) Reactions at 21.6 MeV Proton Incident Energy

    NASA Astrophysics Data System (ADS)

    Büyükuslu, H.; Kaplan, A.; Tel, E.; Aydin, A.; Y?ld?r?m, G.

    2010-02-01

    Palladium, which is a rare and lustrous silvery-white color from precious metals, plays important role in fusion-fission reactions and different fields of nuclear technology. In addition, it is used for not only cold fusion experiments but also separation of hydrogen isotopes researches for fusion reactors. In this study, neutron-emission spectra produced by (p,xn) reactions for structural fusion material 104,105,106,108,110Pd isotopes have been investigated by a proton beam at 21.6 MeV. Moreover, multiple pre-equilibrium mean free paths constant from internal transition, and the pre-equilibrium and equilibrium level density parameters have been analyzed for some (p,xn) neutron-emission spectra calculated. New evaluated hybrid model and geometry dependent hybrid model, full exciton model and cascade exciton model were used to calculate the pre-equilibrium neutron-emission spectra. For the reaction equilibrium component, Weisskopf-Ewing model calculations were preferred. The obtained results have been discussed and compared with the available experimental data and found agreement with each other.

  4. DISCOVERY OF Fe K{alpha} X-RAY REVERBERATION AROUND THE BLACK HOLES IN MCG-5-23-16 AND NGC 7314

    SciTech Connect

    Zoghbi, A.; Reynolds, C.; Cackett, E. M.; Miniutti, G.; Kara, E.; Fabian, A. C.

    2013-04-20

    Several X-ray observations have recently revealed the presence of reverberation time delays between spectral components in active galactic nuclei. Most of the observed lags are between the power-law Comptonization component, seen directly, and the soft excess produced by reflection in the vicinity of the black hole. NGC 4151 was the first object to show these lags in the iron K band. Here, we report the discovery of reverberation lags in the Fe K band in two other sources: MCG-5-23-16 and NGC 7314. In both objects, the 6-7 keV band, where the Fe K{alpha} line peaks, lags the bands at lower and higher energies with a time delay of {approx}1 ks. These lags are unlikely to be due to the narrow Fe K{alpha} line. They are fully consistent with reverberation of the relativistically broadened iron K{alpha} line. The measured lags, their time scale, and spectral modeling indicate that most of the radiation is emitted at {approx}5 and 24 gravitational radii for MCG-5-23-16 and NGC 7314, respectively.

  5. The Broad Iron K-alpha line of Cygnus X-1 as Seen by XMM-Newton in the EPIC-pn Modified Timing Mode

    NASA Technical Reports Server (NTRS)

    Duro, Refiz; Dauser, Thomas; Wilms, Jorn; Pottschmidt, Katja; Nowak, Michael A.; Fritz, Sonja; Kendziorra, Eckhard; Kirsch, Marcus G. F.; Reynolds, Christopher S.; Staubert, Rudiger

    2011-01-01

    We present the analysis of the broadened, flourescent iron K(alpha) line in simultaneous XMM-Newton and RXTE data from the black hole Cygnus X-I. The XMM-Newton data were taken in a modified version of the Timing Mode of the EPIC-pn camera. In this mode the lower energy threshold of the instrument is increased to 2.8 keV to avoid telemetry drop outs due to the brightness of the source, while at the same time preserving the signal to noise ratio in the Fe K(alpha) band. We find that the best-fit spectrum consists of the sum of an exponentially cut-off power-law and relativistically smeared, ionized reflection. The shape of the broadened Fe K(alpha) feature is due to strong Compton broadening combined with relativistic broadening. Assuming a standard, thin accretion disk, the black hole is close to maximally rotating. Key words. X-rays: binaries - black hole physics - gravitation

  6. Simultaneous X-ray and Far-Ultraviolet Spectra of AGN with ASCA and HUT

    NASA Technical Reports Server (NTRS)

    Kriss, Gerard A.

    1997-01-01

    We obtained ASCA spectra of the Seyfert 1 galaxy NGC 3516 in March 1995. Simultaneous far-UV observations were obtained with the Hopkins Ultraviolet Telescope on the Astro-2 shuttle mission. The ASCA spectrum shows a lightly absorbed power law of energy index 0.78. The low energy absorbing column is significantly less than previously seen. Prominent 0 VII and 0 VIII absorption edges are visible, but, consistent with the much lower total absorbing column, no Fe K absorption edge is detectable. A weak, narrow Fe K(alpha) emission line from cold material is present as well as a broad Fe K(alpha) line. These features are similar to those reported in other Seyfert 1 galaxies. A single warm absorber model provides only an imperfect description of the low energy absorption. In addition to a highly ionized absorber with ionization parameter U = 1.66 and a total column density of 1.4 x 10(exp 22)/sq cm, adding a lower ionization absorber with U = 0.32 and a total column of 6.9 x 10(exp 21)/sq cm significantly improves the fit. The contribution of resonant line scattering to our warm absorber models limits the Doppler parameter to less than 160 km/s at 90% confidence. Turbulence at the sound speed of the photoionized gas provides the best fit. None of the warm absorber models fit to the X-ray spectrum can match the observed equivalent widths of all the UV absorption lines. Accounting for the X-ray and UV absorption simultaneously requires an absorbing region with a broad range of ionization parameters and column densities.

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

    SciTech Connect

    Jester, Sebastian; Harris, D.E.; Marshall, H.L.; Meisenheimer, K.; /Heidelberg, Max Planck Inst. Astron.

    2006-05-01

    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.

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

    SciTech Connect

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

    2007-09-15

    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.

  9. Predicted Fe II Spectra plus UV through sub-mm Emission Line Fluxes for Other Species Arising in Narrow Line Regions of AGNs

    NASA Astrophysics Data System (ADS)

    Verner, Ekaterina; Bruhweiler, F. C.; Wills, B. J.

    2009-01-01

    Optical and UV spectra indicate pronounced Fe II emission from multitudinous lines superposed on the underlying UV and optical continua of Seyferts and QSOs. Although the intrinsic UV of the these objects exhibit strong Fe II emission arising in higher density Broad Line Region (BLR) gas, observations at visual wavelengths indicate Fe II originating in both BLR and lower density Narrow Line Region (NLR) gas. Our modeling of observed intrinsic UV Fe II emission produces better fits with both BLR and NLR components. We have calculated a grid of photoionization models appropriate for NLR, spanning a range of number density [log (n/cm-3) = 1.0 to 8.0], photoionizing flux [log (?/cm-2 s-1) = 10.0-18.0], microturbulence (? = 0, 2, 10, and 20 km s-1), and abundance (0.1, 0.5, 1.0 and 5 times solar). These models include the effects of cooling from Fe II. The effects of Fe II cooling and the use of a 371 versus an 830-level atom for Fe II in producing the Fe II emission spectra are explored. We present predicted Fe II spectra from the UV through the IR, plus fluxes of important lines of other species from the UV through the sub-mm wavelength range. These predictions, besides being relevant for studies of Fe II in AGNs, provide predicted fluxes for important lines for upcoming missions such as Herschel and SOPHIA. These results will be made available to researchers via the World Wide Web. We acknowledge the support of the National Science Foundation through grant AST-0607465 to CUA.

  10. Role of modifier oxide in emission spectra and kinetics of Er-Ho codoped Na 2SO 4-MO-P 2O 5 glasses

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

    The glasses of the composition 19Na 2SO 4-20MO-60P 2O 5: 1.0Ho 2O 3/1.0Er 2O 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 2SO 4-MO-P 2O 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 4I 13/2 level to 5I 7 of Ho 3+ ions.

  11. A time-dependent density-functional theory and complete active space self-consistent field method study of vibronic absorption and emission spectra of coumarin.

    PubMed

    Li, Junfeng; Rinkevicius, Zilvinas; Cao, Zexing

    2014-07-01

    Time-dependent density-functional theory (TD-DFT) and complete active space multiconfiguration self-consistent field (CASSCF) calculations have been used to determine equilibrium structures and vibrational frequencies of the ground state and several singlet low-lying excited states of coumarin. Vertical and adiabatic transition energies of S1, S2, and S3 have been estimated by TD-B3LYP and CASSCF/PT2. Calculations predict that the dipole-allowed S1 and S3 states have a character of (1)(??*), while the dipole-forbidden (1)(n?*) state is responsible for S2. The vibronic absorption and emission spectra of coumarin have been simulated by TD-B3LYP and CASSCF calculations within the Franck-Condon approximation, respectively. The simulated vibronic spectra show good agreement with the experimental observations available, which allow us to reasonably interpret vibronic features in the S0?S1 and S0?S3 absorption and the S0?S1 emission spectra. Based on the calculated results, activity, intensity, and density of the vibronic transitions and their contribution to the experimental spectrum profile have been discussed. PMID:25005288

  12. Ejecta patterns of Meteor Crater, Arizona derived from the linear un-mixing of TIMS data and laboratory thermal emission spectra

    NASA Technical Reports Server (NTRS)

    Ramsey, Michael S.; Christensen, Philip R.

    1992-01-01

    Accurate interpretation of thermal infrared data depends upon the understanding and removal of complicating effects. These effects may include physical mixing of various mineralogies and particle sizes, atmospheric absorption and emission, surficial coatings, geometry effects, and differential surface temperatures. The focus is the examination of the linear spectral mixing of individual mineral or endmember spectra. Linear addition of spectra, for particles larger than the wavelength, allows for a straight-forward method of deconvolving the observed spectra, predicting a volume percent of each endmember. The 'forward analysis' of linear mixing (comparing the spectra of physical mixtures to numerical mixtures) has received much attention. The reverse approach of un-mixing thermal emission spectra was examined with remotely sensed data, but no laboratory verification exists. Understanding of the effects of spectral mixing on high resolution laboratory spectra allows for the extrapolation to lower resolution, and often more complicated, remotely gathered data. Thermal Infrared Multispectral Scanner (TIMS) data for Meteor Crater, Arizona were acquired in Sep. 1987. The spectral un-mixing of these data gives a unique test of the laboratory results. Meteor Crater (1.2 km in diameter and 180 m deep) is located in north-central Arizona, west of Canyon Diablo. The arid environment, paucity of vegetation, and low relief make the region ideal for remote data acquisition. Within the horizontal sedimentary sequence that forms the upper Colorado Plateau, the oldest unit sampled by the impact crater was the Permian Coconino Sandstone. A thin bed of the Toroweap Formation, also of Permian age, conformably overlays the Coconino. Above the Toroweap lies the Permian Kiabab Limestone which, in turn, is covered by a thin veneer of the Moenkopi Formation. The Moenkopi is Triassic in age and has two distinct sub-units in the vicinity of the crater. The lower Wupatki member is a fine-grained sandstone, while the upper Moqui member is a fissile siltstone. Ejecta from these units are preserved as inverted stratigraphy up to 2 crater radii from the rim. The mineralogical contrast between the units, relative lack of post-emplacement erosion and ejecta mixing provide a unique site to apply the un-mixing model. Selection of the aforementioned units as endmembers reveals distinct patterns in the ejecta of the crater.

  13. Probing dynamics in the Franck--Condon and exit channel regions of dissociating H[sub 2]S: Emission spectra upon tunable excitation from 199--203 nm

    SciTech Connect

    Browning, P.W.; Jensen, E.; Waschewsky, G.C.G.; Tate, M.R.; Butler, L.J. ); Hessler, J.P. )

    1994-10-01

    This emission, into local mode eigenstates such as 00[sup +]1, 11[sup +]0, 11[sup +]1, 21[sup +]0, 21[sup +]1, evidences the antisymmetric dissociative motion and bending induced near the conical intersection, and dominates the spectrum at excitation wavelengths only near 200 nm. We analyze the excitation wavelength dependence of these features and also of the [ital n]0[sup +]0 progression for [ital n][ge]4, which reflect the exit channel dynamics. The excitation wavelength dependence shows that while the emission spectra do not reveal any dynamics unique to scattering states that access a symmetric stretch resonance in the Franck--Condon region, they do reveal the energy location of and the dynamics at the conical intersection. A reanalysis of other workers' measurements of the SH product vibrational state distribution shows that [ital v]=0 products are strongly favored at excitation wavelengths near the conical intersection.

  14. The effects of side-chain-induced disorder on the emission spectra and quantum yields of oligothiophene nano-aggregates. A combined experimental and MD-TDDFT study

    SciTech Connect

    Hong, Jiyun; Jeon, SuKyung; Kim, Janice J.; Devi, Diane; Chacon-Madrid, Kelly; Lee, Wynee; Koo, Seung Moh; Wildeman, Jurjen; Sfeir, Matthew Y.; Peteanu, Linda A.; Wen, Jin; Ma, Jing

    2014-07-24

    Oligomeric thiophenes are commonly-used components in organic electronics and solar cells. These molecules stack and/or aggregate readily under the processing conditions used to form thin films for these applications, significantly altering their optical and charge-transport properties. To determine how these effects depend on the substitution pattern of the thiophene main chains, nano-aggregates of three sexi-thiophene (6T) oligomers having different alkyl substitution patterns were formed using solvent poisoning techniques and studied using steady-state and time-resolved emission spectroscopy. The results indicate the substantial role played by the side-chain substituents in determining the emissive properties of these species. Both the measured spectral changes and their dependence on substitution are well modeled by combined quantum chemistry and molecular dynamics simulations. The simulations connect the side-chain-induced disorder, which determines the favorable chain packing configurations within the aggregates, with their measured electronic spectra.

  15. The effects of side-chain-induced disorder on the emission spectra and quantum yields of oligothiophene nano-aggregates. A combined experimental and MD-TDDFT study

    DOE PAGESBeta

    Hong, Jiyun; Jeon, SuKyung; Kim, Janice J.; Devi, Diane; Chacon-Madrid, Kelly; Lee, Wynee; Koo, Seung Moh; Wildeman, Jurjen; Sfeir, Matthew Y.; Peteanu, Linda A.; et al

    2014-07-24

    Oligomeric thiophenes are commonly-used components in organic electronics and solar cells. These molecules stack and/or aggregate readily under the processing conditions used to form thin films for these applications, significantly altering their optical and charge-transport properties. To determine how these effects depend on the substitution pattern of the thiophene main chains, nano-aggregates of three sexi-thiophene (6T) oligomers having different alkyl substitution patterns were formed using solvent poisoning techniques and studied using steady-state and time-resolved emission spectroscopy. The results indicate the substantial role played by the side-chain substituents in determining the emissive properties of these species. Both the measured spectral changesmore »and their dependence on substitution are well modeled by combined quantum chemistry and molecular dynamics simulations. The simulations connect the side-chain-induced disorder, which determines the favorable chain packing configurations within the aggregates, with their measured electronic spectra.« less

  16. The influence of visible light and inorganic pigments on fluorescence excitation emission spectra of egg-, casein- and collagen-based painting media

    NASA Astrophysics Data System (ADS)

    Nevin, A.; Anglos, D.; Cather, S.; Burnstock, A.

    2008-07-01

    Spectrofluorimetric analysis of proteinaceous binding media is particularly promising because proteins employed in paintings are often fluorescent and media from different sources have significantly different fluorescence spectral profiles. Protein-based binding media derived from eggs, milk and animal tissue have been used for painting and for conservation, but their analysis using non-destructive techniques is complicated by interferences with pigments, their degradation and their low concentration. Changes in the fluorescence excitation emission spectra of films of binding media following artificial ageing to an equivalent of 50 and 100 years of museum lighting include the reduction of bands ascribed to tyrosine, tryptophan and Maillard reaction products and an increase in fluorescent photodegradation. Fluorescence of naturally aged paint is dependent on the nature of the pigment present and, with egg-based media, in comparison with un-pigmented films, emissions ascribed to amino acids are more pronounced.

  17. Lines and continuum sky emission in the near infrared: observational constraints from deep high spectral resolution spectra with GIANO-TNG

    E-print Network

    Oliva, E; Scuderi, S; Benatti, S; Carleo, I; Lapenna, E; Mucciarelli, A; Baffa, C; Biliotti, V; Carbonaro, L; Falcini, G; Giani, E; Iuzzolino, M; Massi, F; Sanna, N; Sozzi, M; Tozzi, A; Ghedina, A; Ghinassi, F; Lodi, M; Harutyunyan, A; Pedani, M

    2015-01-01

    Aims Determining the intensity of lines and continuum airglow emission in the H-band is important for the design of faint-object infrared spectrographs. Existing spectra at low/medium resolution cannot disentangle the true sky-continuum from instrumental effects (e.g. diffuse light in the wings of strong lines). We aim to obtain, for the first time, a high resolution infrared spectrum deep enough to set significant constraints on the continuum emission between the lines in the H-band. Methods During the second commissioning run of the GIANO high-resolution infrared spectrograph at La Palma Observatory, we pointed the instrument directly to the sky and obtained a deep spectrum that extends from 0.97 to 2.4 micron. Results The spectrum shows about 1500 emission lines, a factor of two more than in previous works. Of these, 80% are identified as OH transitions; half of these are from highly excited molecules (hot-OH component) that are not included in the OH airglow emission models normally used for astronomical ...

  18. A Combined Optical and X-ray Study of Unobscured Type 1 AGN. II. Relation Between X-ray Emission and Optical Spectra

    E-print Network

    Jin, C; Done, C

    2012-01-01

    In this paper we study the properties of the optical spectra of Type 1 active galactic nuclei (AGNs) by using the unobscured hard X-ray emission as a diagnostic. We develop the `Correlation Spectrum Technique' (CST) and use this to show the strength of correlation between the hard X-ray luminosity and each wavelength of the optical spectrum. This shows that for Broad Line Seyfert 1s all the strong emission lines (broad component of H\\alpha and H\\beta, [NeIII] \\lambda\\lambda 3869/3967, [OI] \\lambda\\lambda 6300/6364, [OII] \\lambda\\lambda 3726/3729, [OIII] \\lambda\\lambda 4959/5007) and the optical underlying continuum all strongly correlate with the hard X-ray emission. But the NLS1s appear to be somewhat different. Among the various Balmer line components and the broadband SED components, the best correlation exists between the hard X-ray component and broad component (BC) of the Balmer lines, which supports the view that broad line region (BLR) has the closest link with the AGN's compact X-ray emission. The eq...

  19. The 3D-HST Survey: Hubble Space Telescope WFC3/G141 grism spectra, redshifts, and emission line measurements for $\\sim 100,000$ galaxies

    E-print Network

    Momcheva, Ivelina G; van Dokkum, Pieter G; Skelton, Rosalind E; Whitaker, Katherine E; Nelson, Erica J; Fumagalli, Mattia; Maseda, Michael V; Leja, Joel; Franx, Marijn; Rix, Hans-Walter; Bezanson, Rachel; Da Cunha, Elisabete; Dickey, Claire; Schreiber, Natascha M Förster; Illingworth, Garth; Kriek, Mariska; Labbé, Ivo; Lange, Johannes Ulf; Lundgren, Britt F; Magee, Daniel; Marchesini, Danilo; Oesch, Pascal; Pacifici, Camilla; Patel, Shannon G; Price, Sedona; Tal, Tomer; Wake, David A; van der Wel, Arjen; Wuyts, Stijn

    2015-01-01

    We present reduced data and data products from the 3D-HST survey, a 248-orbit HST Treasury program. The survey obtained WFC3 G141 grism spectroscopy in four of the five CANDELS fields: AEGIS, COSMOS, GOODS-S, and UDS, along with WFC3 $H_{140}$ imaging, parallel ACS G800L spectroscopy, and parallel $I_{814}$ imaging. In a previous paper (Skelton et al. 2014) we presented photometric catalogs in these four fields and in GOODS-N, the fifth CANDELS field. Here we describe and present the WFC3 G141 spectroscopic data, again augmented with data from GO-1600 in GOODS-N. The data analysis is complicated by the fact that no slits are used: all objects in the WFC3 field are dispersed, and many spectra overlap. We developed software to automatically and optimally extract interlaced 2D and 1D spectra for all objects in the Skelton et al. (2014) photometric catalogs. The 2D spectra and the multi-band photometry were fit simultaneously to determine redshifts and emission line strengths, taking the morphology of the galaxie...

  20. Emission lines of Fe XI in the 257--407 A wavelength region observed in solar spectra from EIS/Hinode and SERTS

    E-print Network

    Keenan, F P; Jess, D B; Aggarwal, K M; Mathioudakis, M; Thomas, R J; Brosius, J W; Davila, J M

    2010-01-01

    Theoretical emission-line ratios involving Fe XI transitions in the 257-407 A wavelength range are derived using fully relativistic calculations of radiative rates and electron impact excitation cross sections. These are subsequently compared with both long wavelength channel Extreme-Ultraviolet Imaging Spectrometer (EIS) spectra from the Hinode satellite (covering 245-291 A), and first-order observations (235-449 A) obtained by the Solar Extreme-ultraviolet Research Telescope and Spectrograph (SERTS). The 266.39, 266.60 and 276.36 A lines of Fe XI are detected in two EIS spectra, confirming earlier identifications of these features, and 276.36 A is found to provide an electron density diagnostic when ratioed against the 257.55 A transition. Agreement between theory and observation is found to be generally good for the SERTS data sets, with discrepancies normally being due to known line blends, while the 257.55 A feature is detected for the first time in SERTS spectra. The most useful Fe XI electron density d...

  1. HIGH-RESOLUTION ELECTRON-IMPACT EMISSION SPECTRA AND VIBRATIONAL EMISSION CROSS SECTIONS FROM 330-1100 nm FOR N{sub 2}

    SciTech Connect

    Mangina, Rao S.; Ajello, Joseph M.; West, Robert A.; Dziczek, Dariusz

    2011-09-01

    Electron-impact emission cross sections for N{sub 2} were measured in the wavelength range of 330-1100 nm at 25 eV and 100 eV impact energies. Cross sections of several molecular emission bands of the first positive band system B {sup 3}{Pi}{sub g} {sup +}({nu}') {yields} A {sup 3}{Sigma}{sub g} {sup +}({nu}'') and the second positive band system C {sup 3}{Pi}{sub u} ({nu}') {yields} B {sup 3}{Pi}{sub g} ({nu}'') of N{sub 2}, the first negative band (1NB) system B {sup 2}{Sigma}{sub u} {sup +}({nu}') {yields} X {sup 2}{Sigma}{sub g} {sup +}({nu}'') and Meinel band system A {sup 2}{Pi}{sub u} ({nu}') {yields} X {sup 2}{Sigma}{sub g} {sup +}({nu}'') of N{sub 2} {sup +} ions as well as line emissions of N (N I) and N{sup +} (N II) in the visible-optical-near-IR wavelength range reported in this work were measured for the first time in a single experimental setup at high spectral resolving power ({lambda}/{Delta}{lambda} {approx} 10000) under single-collision-scattering geometry and optically thin conditions. Rotational emission lines of N{sub 2} and N{sub 2} {sup +} were observed for strong emission bands at a gas temperature of about 300 K. The absolute cross section of the strongest (0,0) vibrational band at 391.43 nm of 1NB was determined using the standard H{sub {alpha}} emission cross sections of H{sub 2} by electron impact at both 25 eV and 100 eV electron-impact energies, and the cross sections for the remainder of the emissions were determined using (0,0) 1NB value. A comparison of the present emission cross sections with the earlier published data from both electron energy loss and electron-impact-induced fluorescence emission is discussed.

  2. Detailed analysis of hollow ions spectra from dense matter pumped by X-ray emission of relativistic laser plasma

    NASA Astrophysics Data System (ADS)

    Hansen, S. B.; Colgan, J.; Faenov, A. Ya.; Abdallah, J.; Pikuz, S. A.; Skobelev, I. Yu.; Wagenaars, E.; Booth, N.; Culfa, O.; Dance, R. J.; Tallents, G. J.; Evans, R. G.; Gray, R. J.; Kaempfer, T.; Lancaster, K. L.; McKenna, P.; Rossall, A. K.; Schulze, K. S.; Uschmann, I.; Zhidkov, A. G.; Woolsey, N. C.

    2014-03-01

    X-ray emission from hollow ions offers new diagnostic opportunities for dense, strongly coupled plasma. We present extended modeling of the x-ray emission spectrum reported by Colgan et al. [Phys. Rev. Lett. 110, 125001 (2013)] based on two collisional-radiative codes: the hybrid-structure Spectroscopic Collisional-Radiative Atomic Model (SCRAM) and the mixed-unresolved transition arrays (MUTA) ATOMIC model. We show that both accuracy and completeness in the modeled energy level structure are critical for reliable diagnostics, investigate how emission changes with different treatments of ionization potential depression, and discuss two approaches to handling the extensive structure required for hollow-ion models with many multiply excited configurations.

  3. Detailed analysis of hollow ions spectra from dense matter pumped by X-ray emission of relativistic laser plasma

    SciTech Connect

    Hansen, S. B. E-mail: anatolyf@hotmail.com; Colgan, J.; Abdallah, J.; Faenov, A. Ya. E-mail: anatolyf@hotmail.com; Pikuz, S. A.; Skobelev, I. Yu.; Wagenaars, E.; Culfa, O.; Dance, R. J.; Tallents, G. J.; Rossall, A. K.; Woolsey, N. C.; Booth, N.; Lancaster, K. L.; Evans, R. G.; Gray, R. J.; McKenna, P.; Kaempfer, T.; Schulze, K. S.; Uschmann, I.; Institut für Optik und Quantenelektronic, Friedrich-Schiller-Universität Jena, Max-Wien Platz 1, Jena, D-07743 ; and others

    2014-03-15

    X-ray emission from hollow ions offers new diagnostic opportunities for dense, strongly coupled plasma. We present extended modeling of the x-ray emission spectrum reported by Colgan et al. [Phys. Rev. Lett. 110, 125001 (2013)] based on two collisional-radiative codes: the hybrid-structure Spectroscopic Collisional-Radiative Atomic Model (SCRAM) and the mixed-unresolved transition arrays (MUTA) ATOMIC model. We show that both accuracy and completeness in the modeled energy level structure are critical for reliable diagnostics, investigate how emission changes with different treatments of ionization potential depression, and discuss two approaches to handling the extensive structure required for hollow-ion models with many multiply excited configurations.

  4. A Bulk Comptonization Model for the Prompt GRB Emission and its Relation to the Fermi GRB Spectra

    NASA Technical Reports Server (NTRS)

    Kazanas, Demosthenes

    2010-01-01

    We present a model in which the GRB prompt emission at E E(sub peak) is due to bulk Comptonization by the relativistic blast wave motion of either its own synchrotron photons of ambient photons of the stellar configuration that gave birth to the GRB. The bulk Comptonization process then induces the production of relativistic electrons of Lorentz factor equal to that of the blast wave through interactions with its ambient protons. The inverse compton emission of these electrons produces a power law component that extends to multi GeV energies in good agreement with the LAT GRB observations.

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

    SciTech Connect

    Johns, H. M.; Mancini, R. C.; Hakel, P.; Nagayama, T.; Smalyuk, V. A.; Regan, S. P.; Delettrez, J.

    2014-08-15

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

  6. On the Early-Time X-Ray Spectra of Swift Afterglows. I. Evidence for Anomalous Soft X-Ray Emission

    NASA Astrophysics Data System (ADS)

    Butler, N. R.

    2007-02-01

    We have conducted a thorough and blind search for emission lines in >70 Swift X-ray afterglows of total exposure ~107 s. We find that most afterglows are consistent with pure power laws plus extinction. Significant outliers to the population exist at the 5%-10% level and have anomalously soft, possibly thermal spectra. Four bursts are singled out via possible detections of two to five lines: GRB 060218, GRB 060202, GRB 050822, and GRB 050714B. Alternatively, a blackbody model with kT~0.1-0.5 keV can describe the soft emission in each afterglow. The most significant soft-component detections in the full data set of ~2000 spectra correspond to GRB 060218/SN 2006aj, with line significances ranging up to ~20 ?. A thermal plasma model fit to the data indicates that the flux is primarily due to L-shell transitions of Fe at roughly solar abundance. We associate (>4 ? significant) line triggers in the three other events with K-shell transitions in light metals. We favor a model where the possible line emission in these afterglows arises from the mildly relativistic cocoon of matter surrounding the GRB jet as it penetrates and exits the surface of the progenitor star. The emitting material in each burst is at a similar distance ~1012-1013 cm, a similar density ~1017 cm-3, and subject to a similar flux of ionizing radiation. The lines may correlate with the X-ray flaring. For the blackbody interpretation, the soft flux may arise from breakout of the GRB shock or plasma cocoon from the progenitor stellar wind, as recently suggested for GRB 060218 (Campana et al. 2006). Due to the low z of GRB 060218, bursts faint in gamma rays with fluxes dominated by this soft X-ray component could outnumber classical GRBs 100 to 1.

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

    PubMed Central

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

    1992-01-01

    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. PMID:1489915

  8. HST/COS SPECTRA OF DF Tau AND V4046 Sgr: FIRST DETECTION OF MOLECULAR HYDROGEN ABSORPTION AGAINST THE Ly{alpha} EMISSION LINE

    SciTech Connect

    Yang Hao; Linsky, Jeffrey L.; France, Kevin E-mail: jlinsky@jilau1.colorado.edu

    2011-03-20

    We report the first detection of molecular hydrogen (H{sub 2}) absorption in the Ly{alpha} emission line profiles of two classical T Tauri stars (CTTSs), DF Tau and V4046 Sgr, observed by the Hubble Space Telescope/Cosmic Origins Spectrograph. This absorption is the energy source for many of the Lyman-band H{sub 2} fluorescent lines commonly seen in the far-ultraviolet spectra of CTTSs. We find that the absorbed energy in the H{sub 2} pumping transitions from a portion of the Ly{alpha} line significantly differ from the amount of energy in the resulting fluorescent emission. By assuming additional absorption in the H I Ly{alpha} profile along our light of sight, we can correct the H{sub 2} absorption/emission ratios so that they are close to unity. The required H I absorption for DF Tau is at a velocity close to the radial velocity of the star, consistent with H I absorption in the edge-on disk and interstellar medium. For V4046 Sgr, a nearly face-on system, the required absorption is between +100 km s{sup -1} and +290 km s{sup -1}, most likely resulting from H I gas in the accretion columns falling onto the star.

  9. The ground-based H-, K-, and L-band absolute emission spectra of HD 209458b

    SciTech Connect

    Zellem, Robert T.; Griffith, Caitlin A.; Deroo, Pieter; Swain, Mark R.; Waldmann, Ingo P.

    2014-11-20

    Here we explore the capabilities of NASA's 3.0 m Infrared Telescope Facility (IRTF) and SpeX spectrometer and the 5.08 m Hale telescope with the TripleSpec spectrometer with near-infrared H-, K-, and L-band measurements of HD 209458b's secondary eclipse. Our IRTF/SpeX data are the first absolute L-band spectroscopic emission measurements of any exoplanet other than the hot Jupiter HD 189733b. Previous measurements of HD 189733b's L band indicate bright emission hypothesized to result from non-LTE CH{sub 4} ?{sub 3} fluorescence. We do not detect a similar bright 3.3 ?m feature to ?3?, suggesting that fluorescence does not need to be invoked to explain HD 209458b's L-band measurements. The validity of our observation and reduction techniques, which decrease the flux variance by up to 2.8 orders of magnitude, is reinforced by 1? agreement with existent Hubble/NICMOS and Spitzer/IRAC1 observations that overlap the H, K, and L bands, suggesting that both IRTF/SpeX and Palomar/TripleSpec can measure an exoplanet's emission with high precision.

  10. Detection of Copper (II) and Cadmium (II) binding to dissolved organic matter from macrophyte decomposition by fluorescence excitation-emission matrix spectra combined with parallel factor analysis.

    PubMed

    Yuan, Dong-hai; Guo, Xu-jing; Wen, Li; He, Lian-sheng; Wang, Jing-gang; Li, Jun-qi

    2015-09-01

    Fluorescence excitation-emission matrix (EEM) spectra coupled with parallel factor analysis (PARAFAC) was used to characterize dissolved organic matter (DOM) derived from macrophyte decomposition, and to study its complexation with Cu (II) and Cd (II). Both the protein-like and the humic-like components showed a marked quenching effect by Cu (II). Negligible quenching effects were found for Cd (II) by components 1, 5 and 6. The stability constants and the fraction of the binding fluorophores for humic-like components and Cu (II) can be influenced by macrophyte decomposition of various weight gradients in aquatic plants. Macrophyte decomposition within the scope of the appropriate aquatic phytomass can maximize the stability constant of DOM-metal complexes. A large amount of organic matter was introduced into the aquatic environment by macrophyte decomposition, suggesting that the potential risk of DOM as a carrier of heavy metal contamination in macrophytic lakes should not be ignored. PMID:25969375

  11. Lines and continuum sky emission in the near infrared: observational constraints from deep high spectral resolution spectra with GIANO-TNG

    NASA Astrophysics Data System (ADS)

    Oliva, E.; Origlia, L.; Scuderi, S.; Benatti, S.; Carleo, I.; Lapenna, E.; Mucciarelli, A.; Baffa, C.; Biliotti, V.; Carbonaro, L.; Falcini, G.; Giani, E.; Iuzzolino, M.; Massi, F.; Sanna, N.; Sozzi, M.; Tozzi, A.; Ghedina, A.; Ghinassi, F.; Lodi, M.; Harutyunyan, A.; Pedani, M.

    2015-09-01

    Aims: Determining the intensity of lines and continuum airglow emission in the H-band is important for the design of faint-object infrared spectrographs. Existing spectra at low or medium resolution cannot disentangle the true sky continuum from instrumental effects (e.g. diffuse light in the wings of strong lines). We aim to obtain, for the first time, a high-resolution infrared spectrum that is deep enough to set significant constraints on the continuum emission between the lines in the H-band. Methods: During the second commissioning run of the GIANO high-resolution infrared spectrograph at La Palma Observatory, we pointed the instrument directly at the sky and obtained a deep spectrum that extends from 0.97 to 2.4 ?m. Results: The spectrum shows about 1500 emission lines, a factor of two more than in previous works. Of these, 80% are identified as OH transitions; half of these are from highly excited molecules (hot-OH component) that are not included in the OH airglow emission models normally used for astronomical applications. The other lines are attributable to O2 or unidentified. Several of the faint lines are in spectral regions that were previously believed to be free of line emission. The continuum in the H-band is marginally detected at a level of about 300 photons/m2/s/arcsec2/?m, equivalent to 20.1 AB-mag/arcsec2. The observed spectrum and the list of observed sky lines are published at the CDS. Conclusions: Our measurements indicate that the sky continuum in the H-band could be even darker than previously believed. However, the myriad of airglow emission lines severely limits the spectral ranges where very low background can be effectively achieved with low- or medium-resolution spectrographs. We identify a few spectral bands that could still remain quite dark at the resolving power foreseen for VLT-MOONS (R ? 6600). Tables 1, 2, and 4 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/581/A47

  12. Asymptotically-Equal-To 10 eV ionization shift in Ir K{alpha}{sub 2} from a near-coincident Lu K-edge

    SciTech Connect

    Pereira, N. R.; Weber, B. V.; Phipps, D.; Schumer, J. W.; Seely, J. F.; Carroll, J. J.; VanHoy, J. R.; Slabkowska, K.; Polasik, M.

    2012-10-15

    Close to an x-ray filter's K-edge the transmission depends strongly on the photon energy. For a few atom pairs, the K-edge of one is only a few tens of eV higher than a K-line energy of another, so that a small change in the line's energy becomes a measurable change in intensity behind such a matching filter. Lutetium's K-edge is Asymptotically-Equal-To 27 eV above iridium's K{alpha}{sub 2} line, Asymptotically-Equal-To 63.287 keV for cold Ir. A Lu filter reduces this line's intensity by Asymptotically-Equal-To 10 % when it is emitted by a plasma, indicating an ionization shift {Delta}E Asymptotically-Equal-To 10{+-}1 eV.

  13. [Excitation-Emission Matrix Fluorescence Spectra Characteristics of DOM in Integrated Verical Flow Constructed Wetland for Treating Eutrophic Water].

    PubMed

    Li, Shu-juan; Ge, Li-yun; Deng, Huan-huan

    2015-04-01

    Three-dimensional fluorescence parameters can reflect classification, properties and content change of pollutants in wastewater treatment. In the present paper, by using three-dimensional fluorescence characteristic analysis, comparative analysis of conventional organic pollutants such as COD, TN and TP, and three dimensional fluorescence spectrum analysis, the classification and content of dissolved organic pollutants were identified. We studied fluorescence spectra, fluorescence peak (R. U.), fluorescence index (FI), humification index (HIX) of DOM's four components in the entrance and effluent water and interstitial water, as well as the correlation between these four components and COD, TN and TP. The results showed that the position and intensity of the characteristic fluorescence peak center changed significantly before and after sewage treatment, indicating that the relative composition and content of the organic wastewater varied with wastewater treatment. Furthermore, the test results presented that humic-like composition was not degraded significantly, while protein-like composition was degraded significantly. And the protein-like component and COD, TN and TP presented significant positive correlation. This paper analyzed the fluorescence characteristics changes of dissolved organic matter in sewage treatment by using three-dimensional fluorescence spectrometry, and discussed the feasibility of three-dimensional fluorescence technique applied for description of dissolved organic pollutant degradation rule in the wastewater treatment process. PMID:26197580

  14. Palagonitic (Not Andesitic) Mars: Evidence from Thermal Emission and VNIR Spectra of Palgonitic Alteration Rinds on Basaltic Rock

    NASA Technical Reports Server (NTRS)

    Morris, R. V.; Graff, T. G.; Mertzman, S. A.; Lane, M. D.; Christensen, P. R.

    2003-01-01

    Visible and near-IR (VNIR) spectra of both Martian bright and dark regions are characterized by a ferric absorption edge extending from approx. 400 to 750 nm, with bright regions having about twice the reflectivity at 750 nm as dark regions. Between 750 nm to beyond 2000 nm, bright and dark regions have nearly constant and slightly negative spectral slopes, respectively. Depending on location, bright regions have shallow reflectivity minima in the range 850-910 nm that are attributed to ferric oxides. Similarly, dark regions have shallow reflectivity minima near approx. 950 and 1700-2000 nm that are attributed to ferrous silicate minerals (pyroxene). Among terrestrial geologic materials, the best spectral analogues for Martian bright regions are certain palagonitic tephras from Mauna Kea Volcano (Hawaii). By definition, palagonite is a "yellow or orange isotropic mineraloid formed by hydration and devitrification of basaltic glass". The ferric pigment in palagonite is nanometer-sized ferric oxide particles (np-Ox) dispersed throughout the hydrated basaltic glass matrix. The hydration state of the np-Ox particles is not known, but the best Martian spectral analogues contain allophane-like materials and not crystalline phyllosilicates.

  15. Solvent dependence of absorption and emission spectra of Ru(bpy)2(CN)2: experiment and explanation based on electronic structure theory.

    PubMed

    Fodor, Lajos; Lendvay, György; Horváth, Attila

    2007-12-20

    Measurements in acidic media and time-dependent density functional theory and DeltaSCF calculations were performed for Ru(bpy)2(CN)2 in 11 solvents of varying polarity to determine the solvent's influence on the absorption and emission spectra of the complex. The solvent effect caused by both the polarizable continuum nature of the solvent (characterized by the polarizable conductor model), and by the coordination of the cyano groups of the complex by solvent molecules were investigated. Both the absorption and emission maxima show a strong blue shift as the solute-solvent interaction increases, the magnitude of which is in good linear correlation with Gutmann's acceptor number of the solvent. The calculations reproduce the location, shape, and shift of the experimental metal-to-ligand charge transfer bands. The solvent shift is shown to be in good correlation with the charge difference between the Ru atom and the bpy ligand, which in turn is closely related to the HOMO energy. The coordination of the solvent molecule to the cyano group causes a smaller blue shift than the polarizable continuum solvent. The specific solute-solvent interaction becomes dominant, however, when the pH in a protic solvent is small and the complex is protonated. PMID:18031024

  16. Four micron high-resolution spectra of Jupiter in the North Equatorial Belt: H3(+) emissions and the C-12/C-13 ratio

    NASA Technical Reports Server (NTRS)

    Marten, A.; De Bergh, C.; Owen, T.; Gautier, D.; Maillard, J. P.; Drossart, P.; Lutz, B. L.; Orton, G. S.

    1994-01-01

    Spectra of the North Equatorial Belt of Jupiter were obtained in March 1992 at an unapodized resolution of 0.1/cm between 2450 and 2600/cm with the Fourier Transform Spectrometer at the 3.6 m Canada-France-Hawaii Telescope (CFHT) on Mauna Kea. Several emissions from the nu(sub 2) band of H3(+) were detected. The excitation temperature derived from the relative intensities of these emissions averaged over a wide range of longitudes is 800 +/- 100 K, and the H3(+) column density is 1.56(sup +1.0)(sub -0.5) x 10(exp 11)/sq. cm. In addition, several strong absorption features due to (13)CH4 were observed. A comparison between (12)CH4 and (13)CH4 absorptions allowed us to obtain a new measurement of the C-12/C-13 ratio. We found that this ratio, estimated for the first time in this spectral range, is 89 (+/- 25), in agreement with the terrestrial value.

  17. Infrared radiative transfer in atmospheres of Earth-like planets around F, G, K, and M stars. II. Thermal emission spectra influenced by clouds

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    Context. Clouds play an important role in the radiative transfer of planetary atmospheres because of the influence they have on the different molecular signatures through scattering and absorption processes. Furthermore, they are important modulators of the radiative energy budget affecting surface and atmospheric temperatures. Aims: We present a detailed study of the thermal emission of cloud-covered planets orbiting F-, G-, K-, and M-type stars. These Earth-like planets include planets with the same gravity and total irradiation as Earth, but can differ significantly in the upper atmosphere. The impact of single-layered clouds is analyzed to determine what information on the atmosphere may be lost or gained. The planetary spectra are studied at different instrument resolutions and compared to previously calculated low-resolution spectra. Methods: A line-by-line molecular absorption model coupled with a multiple scattering radiative transfer solver was used to calculate the spectra of cloud-covered planets. The atmospheric profiles used in the radiation calculations were obtained with a radiative-convective climate model combined with a parametric cloud description. Results: In the high-resolution flux spectra, clouds changed the intensities and shapes of the bands of CO2, N2O, H2O, CH4, and O3. Some of these bands turned out to be highly reduced by the presence of clouds, which causes difficulties for their detection. The most affected spectral bands resulted for the planet orbiting the F-type star. Clouds could lead to false negative interpretations for the different molecular species investigated. However, at low resolution, clouds were found to be crucial for detecting some of the molecular bands that could not be distinguished in the cloud-free atmospheres. The CO2 bands were found to be less affected by clouds. Radiation sources were visualized with weighting functions at high resolution. Conclusions: Knowledge of the atmospheric temperature profile is essential for estimating the composition and important for avoiding false negative detection of biomarkers, in both cloudy and clear-sky conditions. In particular, a pronounced temperature contrast between the ozone layer and surface or cloud is needed to detect the molecule. Fortunately, the CO2 bands allow temperature estimation from the upper stratosphere down to the troposphere even in the presence of clouds.

  18. STUDYING THE WARM-HOT INTERGALACTIC MEDIUM IN EMISSION

    SciTech Connect

    Takei, Y.; Mitsuda, K.; Ursino, E.; Branchini, E.; Ohashi, T.; Kawahara, H.; Piro, L.; Corsi, A.; Amati, L.; Den Herder, J. W.; Kaastra, J.; Galeazzi, M.; Moscardini, L.; Roncarelli, M.; Nicastro, F.; Paerels, F.; Viel, M.

    2011-06-20

    We assess the possibility of detecting the warm-hot intergalactic medium in emission and characterizing its physical conditions and spatial distribution through spatially resolved X-ray spectroscopy, in the framework of the recently proposed DIOS, EDGE, Xenia, and ORIGIN missions, all of which are equipped with microcalorimeter-based detectors. For this purpose, we analyze a large set of mock emission spectra, extracted from a cosmological hydrodynamical simulation. These mock X-ray spectra are searched for emission features showing both the O VII K{alpha} triplet and O VIII Ly{alpha} line, which constitute a typical signature of the warm-hot gas. Our analysis shows that 1 Ms long exposures and energy resolution of 2.5 eV will allow us to detect about 400 such features per deg{sup 2} with a significance {>=}5{sigma} and reveals that these emission systems are typically associated with density {approx}100 above the mean. The temperature can be estimated from the line ratio with a precision of {approx}20%. The combined effect of contamination from other lines, variation in the level of the continuum, and degradation of the energy resolution reduces these estimates. Yet, with an energy resolution of 7 eV and all these effects taken into account, one still expects about 160 detections per deg{sup 2}. These line systems are sufficient for tracing the spatial distribution of the line-emitting gas, which constitute an additional information, independent from line statistics, to constrain the poorly known cosmic chemical enrichment history and the stellar feedback processes.

  19. XANES spectra of sesqui-oxides of Al, Cr and Fe

    SciTech Connect

    Uda, Masayuki; Yamashita, D.; Terashi, D.; Yamamoto, T.; Osawa,H.; Kanai, K.; Nakamatsu, H.; Perera, Rupert C.C.

    2000-08-07

    Oxygen X-ray absorption near edge (XANES) spectra obtainedfrom alpha-Al2O3, Cr2O3 and alpha-Fe2O3 were found to be clearlydistinguishable. The energy distributions of the XANES spectra werereproduced here fairly well by the DV-X alpha molecular orbitalcalculation On the other hand, O K alpha spectra emitted from theseoxides showed no significant difference. This indicates that the XANES isa very promising candidate to study the chemical environment of anions intypical ionic compounds.

  20. X-ray emission-line spectra of photoionized plasmas - Density sensitivity of the Fe L-shell series

    NASA Technical Reports Server (NTRS)

    Liedahl, Duane A.; Kahn, Steven M.; Osterheld, Albert L.; Goldstein, William H.

    1992-01-01

    The circumsource environments of accretion-powered X-ray sources are likely to support relatively dense (greater than 10 exp 11/cu cm) photoionized X-ray emission-line regions. The Fe L-shell ions provide a versatile class of plasma diagnostics in this regime, their multielectron structures resulting in diverse spectral phenomena. Attention is given to the spectral response of Fe L-shell ions to variations in electron density over the range 10 exp 11 to 10 exp 16/cu cm. It is found that density-sensitive line ratios exist in the wavelength interval 12-17 A for the ions Fe XVII-XXI. The prominent role of radiative recombination in the population kinetics distinguishes the density-sensitive Fe lines in photoionized plasmas from those which operate in coronal equilibrium plasmas. The results of detailed atomic modeling of these ions are presented and applications to spectroscopic observations of accretion-driven X-ray sources are discussed.

  1. Study of Iron Dimers Reveals Angular Dependence of Valence-to-Core X-ray Emission Spectra

    PubMed Central

    2015-01-01

    Transition-metal K? X-ray emission spectroscopy (XES) is a developing technique that probes the occupied molecular orbitals of a metal complex. As an element-specific probe of metal centers, K? XES is finding increasing applications in catalytic and, in particular, bioinorganic systems. For the continued development of XES as a probe of these complex systems, however, the full range of factors which contribute to XES spectral modulations must be explored. In this report, an investigation of a series of oxo-bridged iron dimers reveals that the intensity of valence-to-core features is sensitive to the Fe–O–Fe bond angle. The intensity of these features has a well-known dependence on metal–ligand bond distance, but a dependence upon bond angle has not previously been documented. Herein, we explore the angular dependence of valence-to-core XES features both experimentally and computationally. Taken together, these results show that, as the Fe–O–Fe angle decreases, the intensity of the K?? feature increases and that this effect is modulated by increasing amounts of Fe np mixing into the O 2s orbital at smaller bond angles. The relevance of these findings to the identification of oxygenated intermediates in bioinorganic systems is highlighted, with special emphasis given to the case of soluble methane monooxygenase. PMID:25211540

  2. Estimation of Mass-Loss Rates from Emission Line Profiles in the UV Spectra of Cool Stars

    NASA Technical Reports Server (NTRS)

    Carpenter, K. G.; Robinson, R. D.; Harper, G. M.

    1999-01-01

    The photon-scattering winds of cool, low-gravity stars (K-M giants and supergiants) produce absorption features in the strong chromospheric emission lines. This provides us with an opportunity to assess important parameters of the wind, including flow and turbulent velocities, the optical depth of the wind above the region of photon creation, and the star's mass-loss rate. We have used the Lamers et al. Sobolev with Exact Integration (SEI) radiative transfer code along with simple models of the outer atmospheric structure to compute synthetic line profiles for comparison with the observed line profiles. The SEI code has the advantage of being computationally fast and allows a great number of possible wind models to be examined. We therefore use it here to obtain initial first-order estimates of the wind parameters. More sophisticated, but more time-consuming and resource intensive calculations will be performed at a later date, using the SEI-deduced wind parameters as a starting point. A comparison of the profiles over a range of wind velocity laws, turbulence values, and line opacities allows us to constrain the wind parameters, and to estimate the mass-loss rates. We have applied this analysis technique (using lines of Mg II, 0 I, and Fe II) so far to four stars: the normal K5-giant alpha Tau, the hybrid K-giant gamma Dra, the K5 supergiant lambda Vel, and the M-giant gamma Cru. We present in this paper a description of the technique, including the assumptions which go into its use, an assessment of its robustness, and the results of our analysis.

  3. The Infrared Spectra of Polycyclic Aromatic Hydrocarbons with Excess Peripheral H Atoms (H(sub n)-PAHs) and their Relation to the 3.4 and 6.9 Micrometer PAH Emission Features

    NASA Technical Reports Server (NTRS)

    Sandford, Scott A.; Bernstein, Max P.; Materese, Christopher K.

    2013-01-01

    A population of polycyclic aromatic hydrocarbons (PAHs) and related materials are thought to be responsible for the family of infrared emission features that are seen towards a wide variety of astrophysical environments. A potentially important subclass of these materials are polycyclic aromatic hydrocarbons whose edges contain excess H atoms (H(sub n)-PAHs). While it has been suggested that this type of compound may be present in the interstellar population, it has been difficult to properly assess this possibility because of a lack of suitable infrared laboratory spectra to assist with analysis of the astronomical data. We present the 4000-500 cm(exp -1) (2.5-20 micrometers) infrared spectra of 23 H(sub n)-PAHs and related molecules isolated in argon matrices, under conditions suitable for use in the interpretation of astronomical data. The spectra of molecules with mixed aromatic and aliphatic domains show unique characteristics that distinguish them from their fully aromatic PAH equivalents. We discuss the changes to the spectra of these types of molecules as they transition from fully aromatic to fully aliphatic forms. The implications for the interpretation of astronomical spectra are discussed with specific emphasis on the 3.4 and 6.9 micrometer features. Laboratory data is compared with emission spectra from IRAS 21282+5050, an object with normal PAH emission features, in addition to IRAS 22272+5435 and IRAS 0496+3429, two protoplanetary nebulae with abnormally large 3.4 micrometer features. We show that 'normal' PAH emission objects contain relatively few H(sub n)-PAHs in their emitter populations, but less evolved protoplanetary nebulae may contain significant abundances of these molecules.

  4. Combining Single-Molecule Optical Trapping and Small-Angle X-Ray Scattering Measurements to Compute the Persistence Length of a Protein ER/K [alpha]-Helix

    SciTech Connect

    Sivaramakrishnan, S.; Sung, J.; Ali, M.; Doniach, S.; Flyvbjerg, H.; Spudich, J.A.

    2010-01-12

    A relatively unknown protein structure motif forms stable isolated single {alpha}-helices, termed ER/K {alpha}-helices, in a wide variety of proteins and has been shown to be essential for the function of some molecular motors. The flexibility of the ER/K {alpha}-helix determines whether it behaves as a force transducer, rigid spacer, or flexible linker in proteins. In this study, we quantify this flexibility in terms of persistence length, namely the length scale over which it is rigid. We use single-molecule optical trapping and small-angle x-ray scattering, combined with Monte Carlo simulations to demonstrate that the Kelch ER/K {alpha}-helix behaves as a wormlike chain with a persistence length of 15 nm or 28 turns of {alpha}-helix. The ER/K {alpha}-helix length in proteins varies from 3 to 60 nm, with a median length of 5 nm. Knowledge of its persistence length enables us to define its function as a rigid spacer in a translation initiation factor, as a force transducer in the mechanoenzyme myosin VI, and as a flexible spacer in the Kelch-motif-containing protein.

  5. Possible Charge-Exchange X-Ray Emission in the Cygnus Loop Detected with Suzaku

    NASA Technical Reports Server (NTRS)

    Katsuda, Satoru; Tsunemi, Hiroshi; Mori, Koji; Uchida, Hiroyuki; Kosugi, Hiroko; Kimura, Masashi; Nakajima, Hiroshi; Takakura, Satoru; Petre, Robert; Hewitt. John W.; Yamaguchi, Hiroya

    2011-01-01

    X-ray spectroscopic measurements of the Cygnus Loop supernova remnant indicate that metal abundances throughout most of the remnant s rim are depleted to approx.0.2 times the solar value. However, recent X-ray studies have revealed in some narrow regions along the outermost rim anomalously "enhanced" abundances (up to approx. 1 solar). The reason for these anomalous abundances is not understood. Here, we examine X-ray spectra in annular sectors covering nearly the entire rim of the Cygnus Loop using Suzaku (21 pointings) and XMM-Newton (1 pointing). We find that spectra in the "enhanced" abundance regions commonly show a strong emission feature at approx.0.7 keV. This feature is likely a complex of He-like O K(gamma + delta + epsilon), although other possibilities cannot be fully excluded. The intensity of this emission relative to He-like O K(alpha) appears to be too high to be explained as thermal emission. This fact, as well as the spatial concentration of the anomalous abundances in the outermost rim, leads us to propose an origin from charge-exchange processes between neutrals and H-like O. We show that the presence of charge-exchange emission could lead to the inference of apparently "enhanced" metal abundances using pure thermal emission models. Accounting for charge-exchange emission, the actual abundances could be uniformly low throughout the rim. The overall abundance depletion remains an open question. Subject headings: ISM: abundances ISM: individual objects (Cygnus Loop) ISM: supernova remnants X-rays: ISM atomic processes

  6. The relation between AGN hard X-ray emission and mid-infrared continuum from ISO spectra: Scatter and unification aspects

    NASA Astrophysics Data System (ADS)

    Lutz, D.; Maiolino, R.; Spoon, H. W. W.; Moorwood, A. F. M.

    2004-05-01

    We use mid-infrared spectral decomposition to separate the 6 ?m mid-infrared AGN continuum from the host emission in the ISO low resolution spectra of 71 active galaxies and compare the results to observed and intrinsic 2-10 keV hard X-ray fluxes from the literature. We find a correlation between mid-infrared luminosity and absorption corrected hard X-ray luminosity, but the scatter is about an order of magnitude, significantly larger than previously found with smaller statistics. Main contributors to this scatter are likely variations in the geometry of absorbing dust, and AGN variability in combination with non-simultaneous observations. There is no significant difference between type 1 and type 2 objects in the average ratio of mid-infrared and hard X-ray emission, a result which is not consistent with the most simple version of a unified scheme in which an optically and geometrically thick torus dominates the mid-infrared AGN continuum. Most probably, significant non-torus contributions to the AGN mid-IR continuum are masking the expected difference between the two types of AGN. Table 1 is 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/418/465 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) with the participation of ISAS and NASA.

  7. THE INFRARED SPECTRA OF POLYCYCLIC AROMATIC HYDROCARBONS WITH EXCESS PERIPHERAL H ATOMS (H {sub n} -PAHs) AND THEIR RELATION TO THE 3.4 AND 6.9 {mu}m PAH EMISSION FEATURES

    SciTech Connect

    Sandford, Scott A.; Bernstein, Max P.; Materese, Christopher K.

    2013-03-01

    Polycyclic aromatic hydrocarbons (PAHs) are likely responsible for the family of infrared emission features seen in a wide variety of astrophysical environments. A potentially important subclass of these materials are PAHs whose edges contain excess H atoms (H {sub n} -PAHs). This type of compound may be present in space, but it has been difficult to assess this possibility because of a lack of suitable laboratory spectra to assist with analysis of astronomical data. We present 4000-500 cm{sup -1} (2.5-20 {mu}m) infrared spectra of 23 H {sub n} -PAHs and related molecules isolated in argon matrices under conditions suitable for interpretation of astronomical data. Spectra of molecules with mixed aromatic and aliphatic domains show characteristics that distinguish them from fully aromatic PAH equivalents. Two major changes occur as PAHs become more hydrogenated: (1) aromatic C-H stretching bands near 3.3 {mu}m weaken and are replaced with stronger aliphatic bands near 3.4 {mu}m, and (2) aromatic C-H out-of-plane bending mode bands in the 11-15 {mu}m region shift and weaken concurrent with growth of a strong aliphatic -CH{sub 2}- deformation mode near 6.9 {mu}m. Implications for interpreting astronomical spectra are discussed with emphasis on the 3.4 and 6.9 {mu}m features. Laboratory data is compared with emission spectra from IRAS 21282+5050, an object with normal PAH emission features, and IRAS 22272+5435 and IRAS 0496+3429, two protoplanetary nebulae with abnormally large 3.4 {mu}m features. We show that 'normal' PAH emission objects contain relatively few H {sub n} -PAHs in their emitter populations, but less evolved protoplanetary nebulae may contain significant abundances of these molecules.

  8. The Infrared Spectra of Polycyclic Aromatic Hydrocarbons with Excess Peripheral H Atoms (Hn-PAHs) and their Relation to the 3.4 and 6.9 µm PAH Emission Features

    PubMed Central

    Sandford, Scott A.; Bernstein, Max P.; Materese, Christopher K.

    2015-01-01

    Polycyclic aromatic hydrocarbons (PAHs) are likely responsible for the family of infrared emission features seen in a wide variety of astrophysical environments. A potentially important subclass of these materials are PAHs whose edges contain excess H atoms (Hn-PAHs). This type of compound may be present in space, but it has been difficult to assess this possibility because of a lack of suitable laboratory spectra to assist with analysis of astronomical data. We present 4000-500 cm?1 (2.5–20 µm) infrared spectra of 23 Hn-PAHs and related molecules isolated in argon matrices under conditions suitable for interpretation of astronomical data. Spectra of molecules with mixed aromatic and aliphatic domains show characteristics that distinguish them from fully aromatic PAH equivalents. Two major changes occur as PAHs become more hydrogenated: (1) aromatic C-H stretching bands near 3.3 µm weaken and are replaced with stronger aliphatic bands near 3.4 µm, and (2) aromatic C-H out-of-plane bending mode bands in the 11–15 µm region shift and weaken concurrent with growth of a strong aliphatic -CH2-deformation mode near 6.9 µm. Implications for interpreting astronomical spectra are discussed with emphasis on the 3.4 and 6.9 µm features. Laboratory data is compared with emission spectra from IRAS 21282+5050, an object with normal PAH emission features, and IRAS 22272+5435 and IRAS 0496+3429, two protoplanetary nebulae with abnormally large 3.4 µm features. We show that ‘normal’ PAH emission objects contain relatively few Hn-PAHs in their emitter populations, but less evolved protoplanetary nebulae may contain significant abundances of these molecules. PMID:26435553

  9. Relativistic Iron Emission and Disk Reflection in Galactic Microquasar XTE J1748-288

    E-print Network

    J. M. Miller; D. W. Fox; T. DiMatteo; R. Wijnands; T. Belloni; D. Pooley; C. Kouveliotou; W. H. G. Lewin

    2000-08-24

    We report evidence for an Fe K-alpha fluorescence line feature and disk reflection in the Very High, High, and Low State X-ray spectra of the galactic microquasar XTE J1748-288 during its June~1998 outburst. Spectral analyses are made on data gathered throughout the outburst by the Rossi X-ray Timing Explorer Proportional Counter Array. Gaussian line, relativistic disk emission line, and ionized disk reflection models are fit to the data. In the Very High State the line profile appears strongly redshifted, consistent with disk emission from the innermost stable orbits around a maximally rotating Kerr black hole. In the High State the line profile is less redshifted and increasingly prominent. The Low State line profile is very strong (~0.5 keV equivalent width) and centered at 6.7 +/- 0.10 keV; disk line emission model fits indicate that the inner edge of the disk fluctuates between ~20 and ~100 gravitational radii in this state. The disk reflection fraction is traced through the outburst; reflection from an ionized disk is preferred in the VHS and HS, and reflection from a relatively neutral disk is preferred in the LS. We discuss the implications of our findings for the binary system dynamics and accretion flow geometry in XTE J1748-288.

  10. Relativistic Iron Emission and Disk Reflection in Galactic Microquasar XTE J1748-288

    NASA Technical Reports Server (NTRS)

    Miller, J. M.; Fox, D. W.; DiMatteo, T.; Wijnands, R.; Belloni, T.; Pooley, D.; Kouveliotou, C.; Lewin, W. H. G.

    2001-01-01

    We report evidence for an Fe K-alpha fluorescence line feature and disk reflection in the very high, high-, and low-state X-ray spectra of the Galactic microquasar XTE J1748 - 288 during its 1998 June outburst. Spectral analyses are made on data gathered throughout the outburst by the Rossi X-Ray Timing Explorer Proportional Counter Array. Gaussian line, relativistic disk emission line, and ionized disk reflection models are fitted to the data. In the very high state the line profile appears strongly redshifted, consistent with disk emission from the innermost stable orbits around a maximally rotating Kerr black hole. In the high state the line profile is less redshifted and increasingly prominent. The low-state line profile is very strong (approx. 0.5 keV equivalent width) and centered at 6.7 +/- 0.10 keV; disk line emission model fits indicate that the inner edge of the disk fluctuates between approx. 20R(sub g) and - approx. 100R(sub g) in this state. The disk reflection fraction is traced through the outburst; reflection from an ionized disk is preferred in the very high and high states, and reflection from a relatively neutral disk is preferred in the low state. We discuss the implications of our findings for the binary system dynamics and accretion flow geometry in XTE J1748 - 288.

  11. Relativistic Iron Emission and Disk Reflection in Galactic Microquasar XTE J1748-288

    NASA Technical Reports Server (NTRS)

    Miller, J. M.; Fox, D. W.; Matteo, T. DI; Wijnands, R.; Belloni, T.; Pooley, D.; Kouveliotou, C.; Lewin, W. H. G.

    2001-01-01

    We report evidence for an Fe K(alpha) fluorescence line feature and disk reflection in the very high, high-, and low-state X-ray spectra of the Galactic microquasar XTE J1748-288 during its 1998 June outburst. Spectral analyses are made on data gathered throughout the outburst by the Rossi X-Ray Timing Explorer Proportional Counter Array. Gaussian line, relativistic disk emission line, and ionized disk reflection models are fitted to the data. In the very high state the line profile appears strongly redshifted, consistent with disk emission from the innermost stable orbits around a maximally rotating Kerr black hole. In the high state the line profile is less redshifted and increasingly prominent. The low-state line profile is very strong (approx. 0.5 keV equivalent width) and centered at 6.7 +/- 0.10 keV; disk line emission model fits indicate that the inner edge of the disk fluctuates between approx. 20Rg and approx. 100Rg in this state. The disk reflection fraction is traced through the outburst; reflection from an ionized disk is preferred in the very high and high states, and reflection from a relatively neutral disk is preferred in the low state. We discuss the implications of our findings for the binary system dynamics and accretion flow geometry in XTE J1748-288.

  12. NuSTAR Hard X-ray Survey of the Galactic Center Region I: Hard X-ray Morphology and Spectroscopy of the Diffuse Emission

    E-print Network

    Mori, Kaya; Krivonos, Roman; Hong, Jaesub; Ponti, Gabriele; Bauer, Franz; Perez, Kerstin; Nynka, Melania; Zhang, Shuo; Tomsick, John A; Alexander, David M; Baganoff, Frederick K; Barret, Didier; Barriere, Nicolas; Boggs, Steven E; Canipe, Alicia M; Christensen, Finn E; Craig, William W; Forster, Karl; Giommi, Paolo; Grefenstette, Brian W; Grindlay, Jonathan E; Harrison, Fiona A; Hornstrup, Allan; Kitaguchi, Takao; Koglin, Jason E; Luu, Vy; Madsen, Kristen K; Mao, Peter H; Miyasaka, Hiromasa; Perri, Matteo; Pivovaroff, Michael J; Puccetti, Simonetta; Rana, Vikram; Stern, Daniel; Westergaard, Niels J; Zhang, William W; Zoglauer, Andreas

    2015-01-01

    We present the first sub-arcminute images of the Galactic Center above 10 keV, obtained with NuSTAR. NuSTAR resolves the hard X-ray source IGR J17456-2901 into non-thermal X-ray filaments, molecular clouds, point sources and a previously unknown central component of hard X-ray emission (CHXE). NuSTAR detects four non-thermal X-ray filaments, extending the detection of their power-law spectra with $\\Gamma\\sim1.3$-$2.3$ up to ~50 keV. A morphological and spectral study of the filaments suggests that their origin may be heterogeneous, where previous studies suggested a common origin in young pulsar wind nebulae (PWNe). NuSTAR detects non-thermal X-ray continuum emission spatially correlated with the 6.4 keV Fe K$\\alpha$ fluorescence line emission associated with two Sgr A molecular clouds: MC1 and the Bridge. Broad-band X-ray spectral analysis with a Monte-Carlo based X-ray reflection model self-consistently determined their intrinsic column density ($\\sim10^{23}$ cm$^{-2}$), primary X-ray spectra (power-laws wi...

  13. X-RAY SPECTRA FROM MAGNETOHYDRODYNAMIC SIMULATIONS OF ACCRETING BLACK HOLES

    SciTech Connect

    Schnittman, Jeremy D.; Krolik, Julian H.; Noble, Scott C. E-mail: jhk@pha.jhu.edu

    2013-06-01

    We present the results of a new global radiation transport code coupled to a general relativistic magnetohydrodynamic simulation of an accreting, non-rotating black hole. For the first time, we are able to explain from first principles in a self-consistent way all the components seen in the X-ray spectra of stellar-mass black holes, including a thermal peak and all the features associated with strong hard X-ray emission: a power law extending to high energies, a Compton reflection hump, and a broad iron line. Varying only the mass accretion rate, we are able to reproduce a wide range of X-ray states seen in most galactic black hole sources. The temperature in the corona is T{sub e} {approx} 10 keV in a boundary layer near the disk and rises smoothly to T{sub e} {approx}> 100 keV in low-density regions far above the disk. Even as the disk's reflection edge varies from the horizon out to Almost-Equal-To 6M as the accretion rate decreases, we find that the shape of the Fe K{alpha} line is remarkably constant. This is because photons emitted from the plunging region are strongly beamed into the horizon and never reach the observer. We have also carried out a basic timing analysis of the spectra and find that the fractional variability increases with photon energy and viewer inclination angle, consistent with the coronal hot spot model for X-ray fluctuations.

  14. X-ray spectra of solar flares obtained with a high-resolution bent crystal spectrometer

    NASA Technical Reports Server (NTRS)

    Culhane, J. L.; Rapley, C. G.; Bentley, R. D.; Gabriel, A. H.; Phillips, K. J.; Acton, L. W.; Wolfson, C. J.; Catura, R. C.; Jordan, C.; Antonucci, E.

    1981-01-01

    Preliminary results obtained for three solar flares with the bent crystal spectrometer on the SMM are presented. Resonance and satellite lines of Ca XIX and XVIII and Fe XXV and XXIV are observed together with the Fe XXVI Lyman-alpha line. Plasma properties are deduced from line ratios and evidence is presented for changes of line widths coincident with the occurrence of a hard X-ray impulsive burst. Fe K-alpha spectra from a disk center and a limb flare agree with the predictions of a fluorescence excitation model. However, a transient Fe K-alpha burst observed in a third flare may be explained by the collisional ionization of cool iron by energetic electrons.

  15. X-ray emission from the nuclei, lobes and hot-gas environments of two FR-II radio galaxies

    E-print Network

    J. H. Croston; M. Birkinshaw; M. J. Hardcastle; D. M. Worrall

    2004-06-15

    We report the detection of multiple components of X-ray emission from the two FR-II radio galaxies 3C 223 and 3C 284, based on new XMM-Newton observations. We attribute the detected X-ray emission from the lobes of both sources to inverse-Compton scattering of cosmic microwave background photons. With this model, we find that the magnetic field strength in the lobes is at the equipartition value for 3C 284, and within a factor of two of the equipartition value for 3C 223. We also detect group-scale hot atmospheres around both sources, and determine temperatures and pressures in the gas. The lobes of both sources are in pressure balance with the hot-gas environments, if the lobes contain only the synchrotron-emitting particles and the measured magnetic field strength. The core spectra of both sources contain an unabsorbed soft component, likely to be related to the radio jet, and an additional heavily absorbed power-law component. 3C 223 also displays a bright (EW ~ 500 eV) Fe K-alpha emission line.

  16. Lipid raft facilitated ligation of K-{alpha}1-tubulin by specific antibodies on epithelial cells: Role in pathogenesis of chronic rejection following human lung transplantation

    SciTech Connect

    Tiriveedhi, Venkataswarup; Angaswamy, Nataraju; Weber, Joseph; Mohanakumar, T.

    2010-08-20

    Research highlights: {yields} Addition of KAT Abs (+) sera to NHBE culture causes upregulation of growth factors. {yields} Cholesterol depletion causes down regulation of growth factor expression. {yields} Cholesterol depletion is accompanied by loss of membrane bound caveolin. {yields} Thus, we demonstrate lipid raft are critical for efficient ligation of the KAT Abs. -- Abstract: Long term function of human lung allografts is hindered by development of chronic rejection manifested as Bronchiolitis Obliterans Syndrome (BOS). We have previously identified the development of antibodies (Abs) following lung transplantation to K-{alpha}1-tubulin (KAT), an epithelial surface gap junction cytoskeletal protein, in patients who develop BOS. However, the biochemical and molecular basis of the interactions and signaling cascades mediated by KAT Abs are yet to be defined. In this report, we investigated the biophysical basis of the epithelial cell membrane surface interaction between KAT and its specific Abs. Towards this, we analyzed the role of the lipid raft-domains in the membrane interactions which lead to cell signaling and ultimately increased growth factor expression. Normal human bronchial epithelial (NHBE) cells, upon specific ligation with Abs to KAT obtained either from the serum of BOS(+) patients or monoclonal KAT Abs, resulted in upregulation of growth factors VEGF, PDGF, and bFGF (6.4 {+-} 1.1-, 3.2 {+-} 0.9-, and 3.4 {+-} 1.1-fold increase, respectively) all of which are important in the pathogenesis of BOS. To define the role for lipid raft in augmenting surface interactions, we analyzed the changes in the growth factor expression pattern upon depletion and enrichment with lipid raft following the ligation of the epithelial cell membranes with Abs specific for KAT. NHBE cells cultured in the presence of {beta}-methyl cyclodextran ({beta}MCD) had significantly reduced growth factor expression (1.3 {+-} 0.3, vs {beta}MCD untreated being 6.4 {+-} 1.1-fold increase) upon stimulation with KAT Abs. Depletion of cholesterol on NHBE cells upon treatment with {beta}MCD also resulted in decreased partitioning of caveolin in the membrane fraction indicating a decrease in raft-domains. In conclusion, our results demonstrate an important role for lipid raft-mediated ligation of Abs to KAT on the epithelial cell membrane, which results in the upregulation of growth factor cascades involved in the pathogenesis of BOS following human lung transplantation.

  17. Effects of Palagonitic Dust Coatings on Thermal Emission Spectra of Rocks and Minerals: Implications for Mineralogical Characterization of the Martian Surface by MGS-TES

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    Thermal emission measurements on dust-coated rocks and minerals show that a 300 5m thick layer is required to mask emission from the substrate and that non-linear effects are present. Additional information is contained in the original extended abstract.

  18. 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

    Ullmann, John L; Couture, A J; Keksis, A L; Vieira, D J; O' Donnell, J M; Jandel, M; Haight, R C; Rundberg, R S; Kawano, T; Chyzh, A; Baramsai, B; Wu, C Y; Mitchell, G E; Becker, J A; Krticka, M

    2010-01-01

    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.

  19. Spectral Monitoring of Emission Band HeII+Ha^? in the Spectra of the Wolf-Rayet Type Star HD 192163 during 2005-2008

    NASA Astrophysics Data System (ADS)

    Rustamov, J. N.

    2008-12-01

    Results of investigation of the emission band HeII+Ha using 38 eshelle-spectrograms of the WR type star HD 192163 are presented. Observations carried out in 2005-2008 years at Cassegrain focus of 2-meter 'Zeiss' telescope of the ShAO named after N.Tusi of Azerbaijan National Academy of Sciences, using eshelle-spectrometer. Determined equivalent widths and radial velocity of emission band ^B^NII+^B<95>. Variability of these parameters with the Julian date and variability of the violet part (from Lamda=6496 <9e> to Lamda=6532 <9e>) of the emission band HeII+Ha is revealed.

  20. Investigation of Emission Band HeII+Ha in the Spectra of the Wolf-Rayet Type Star WR 136 = HD 192163

    NASA Astrophysics Data System (ADS)

    Rustamov, J. N.

    2007-06-01

    Results of investigation of the emission band HeII+Ha using 24 eshelle-spectrograms of the WR type star WR 136 = HD 192163 are presented. Observations carried out in 2005-2007 years at Cassegrain focus of 2-meter telescope of the ShAO named after N.Tusi of the National Academy of Sciences of the Azerbaijan, using eshelle-spectrometer. Determined various parameters of the emission band HeII+Ha: equivalent widths, radial velocity, central intensity, widths at half intensity. Variability of the violet part of the emission band HeII+Ha is revealed.

  1. Dissecting the Power Sources of Low-Luminosity Emission-Line Galaxy Nuclei via Comparison of HST-STIS and Ground-Based Spectra

    NASA Astrophysics Data System (ADS)

    Constantin, Anca; Shields, Joseph C.; Ho, Luis C.; Barth, Aaron J.; Filippenko, Alexei V.; Castillo, Christopher A.

    2015-12-01

    Using a sample of ?100 nearby line-emitting galaxy nuclei, we have built the currently definitive atlas of spectroscopic measurements of H? and neighboring emission lines at subarcsecond scales. We employ these data in a quantitative comparison of the nebular emission in Hubble Space Telescope (HST) and ground-based apertures, which offer an order-of-magnitude difference in contrast, and provide new statistical constraints on the degree to which transition objects and low-ionization nuclear emission-line regions (LINERs) are powered by an accreting black hole at ?10 pc. We show that while the small-aperture observations clearly resolve the nebular emission, the aperture dependence in the line ratios is generally weak, and this can be explained by gradients in the density of the line-emitting gas: the higher densities in the more nuclear regions potentially flatten the excitation gradients, suppressing the forbidden emission. The transition objects show a threefold increase in the incidence of broad H? emission in the high-resolution data, as well as the strongest density gradients, supporting the composite model for these systems as accreting sources surrounded by star-forming activity. The narrow-line LINERs appear to be the weaker counterparts of the Type 1 LINERs, where the low accretion rates cause the disappearance of the broad-line component. The enhanced sensitivity of the HST observations reveals a 30% increase in the incidence of accretion-powered systems at z ? 0. A comparison of the strength of the broad-line emission detected at different epochs implies potential broad-line variability on a decade-long timescale, with at least a factor of three in amplitude. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

  2. 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

    Wyart, Jean-Francois . E-mail: jean-francois.wyart@lac.u-psud.fr; Blaise, Jean; Worden, Earl F.

    2005-02-15

    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.

  3. Suzaku Monitoring of Hard X-Ray Emission from Eta Carinae Over a Single Binary Orbital Cycle

    NASA Technical Reports Server (NTRS)

    Hamaguchi, Kenji; Corcoran, Michael F.; Takahashi, Hiromitsu; Yuasa, Takayuki; Ishida, Manabu; Gull, Theodore R.; Pittard, Julian M.; Russell, Christopher M. P.; Madura, Thomas I.

    2014-01-01

    The Suzaku X-ray observatory monitored the supermassive binary system Eta Carinae 10 times during the whole 5.5 year orbital cycle between 2005 and 2011. This series of observations presents the first long-term monitoring of this enigmatic system in the extremely hard X-ray band between 15 and 40 kiloelectron volts. During most of the orbit, the 15-25 kiloelectron volts emission varied similarly to the 2-10 kiloelectron volts emission, indicating an origin in the hard energy tail of the thermal energy approximately equal to 4 kiloelectron volts wind-wind collision (WWC) plasma. However, the 15-25 kiloelectron volts emission declined only by a factor of three around periastron when the 2-10 kiloelectron volts emission dropped by two orders of magnitude due probably to an eclipse of the WWC plasma. The observed minimum in the 15-25 kiloelectron volts emission occurred after the 2-10 kiloelectron volts flux had already recovered by a factor of approximately 3. This may mean that the WWC activity was strong, but hidden behind the thick primary stellar wind during the eclipse. The 25-40 kiloelectron volts flux was rather constant through the orbital cycle, at the level measured with INTEGRAL in 2004. This result may suggest a connection of this flux component to the gamma-ray source detected in this field. The helium-like Fe K-alpha line complex at approximately 6.7 kiloelectron volts became strongly distorted toward periastron as seen in the previous cycle. The 5-9 kiloelectron volts spectra can be reproduced well with a two-component spectral model, which includes plasma in collision equilibrium and a plasma in non-equilibrium ionization (NEI) with tau approximately equal to 10 (sup 11) per cubic centimeter per second. The NEI plasma increases in importance toward periastron.

  4. Palagonitic Mars from Rock Rinds to Dust: Evidence from Visible, Near-IR, and Thermal Emission Spectra of Poorly Crystalline Materials

    NASA Technical Reports Server (NTRS)

    Morris, R. V.; Graff, T. G.; Mertzman, S. A.; Lane, M. D.; Christensen, P. R.

    2003-01-01

    Visible and near-IR (VNIR) spectral data for Martian bright regions are characterized by a general shape consisting of a ferric absorption edge extending from about 400 to 750 nm and relatively constant reflectivity extending from about 750 nm to beyond 2000 nm . Among terrestrial geologic materials, the best spectral analogues are certain palagonic tephras from Mauna Kea Volcano (Hawaii). By definition, palagonite is a yellow or orange isotropic mineraloid formed by hydration and devitrification of basaltic glass. The ferric pigment in palagonite is nanometer-sized ferric oxide particles (np-Ox) dispersed throughout the hydrated basaltic glass matrix. The hydration state of the np-Ox particles is not known, and the best Martian spectral analogues contain allophane-like materials and not crystalline phyllosilicates. We show here that laboratory VNIR and TES spectra of palagonitic alteration rinds developed on basaltic rocks are spectral endmembers that provide a consistent explanation for both VNIR and TES data of Martian dark regions.

  5. Theoretical modeling of UV-Vis absorption and emission spectra in liquid state systems including vibrational and conformational effects: Explicit treatment of the vibronic transitions

    SciTech Connect

    D’Abramo, Marco; Dipartimento di Chimica, Universitá Sapienza, P.le Aldo Moro, 5, 00185, Rome ; Aschi, Massimiliano; Amadei, Andrea

    2014-04-28

    Here, we extend a recently introduced theoretical-computational procedure [M. D’Alessandro, M. Aschi, C. Mazzuca, A. Palleschi, and A. Amadei, J. Chem. Phys. 139, 114102 (2013)] to include quantum vibrational transitions in modelling electronic spectra of atomic molecular systems in condensed phase. The method is based on the combination of Molecular Dynamics simulations and quantum chemical calculations within the Perturbed Matrix Method approach. The main aim of the presented approach is to reproduce as much as possible the spectral line shape which results from a subtle combination of environmental and intrinsic (chromophore) mechanical-dynamical features. As a case study, we were able to model the low energy UV-vis transitions of pyrene in liquid acetonitrile in good agreement with the experimental data.

  6. Size-dependent line broadening in the emission spectra of single GaAs quantum dots: Impact of surface charge on spectral diffusion

    NASA Astrophysics Data System (ADS)

    Ha, Neul; Mano, Takaaki; Chou, Ying-Lin; Wu, Yu-Nien; Cheng, Shun-Jen; Bocquel, Juanita; Koenraad, Paul M.; Ohtake, Akihiro; Sakuma, Yoshiki; Sakoda, Kazuaki; Kuroda, Takashi

    2015-08-01

    Making use of droplet epitaxy, we systematically controlled the height of self-assembled GaAs quantum dots by more than one order of magnitude. The photoluminescence spectra of single quantum dots revealed the strong dependence of the spectral linewidth on the dot height. Tall dots with a height of ˜30 nm showed broad spectral peaks with an average width as large as ˜5 meV , but shallow dots with a height of ˜2 nm showed resolution-limited spectral lines (?120 ? eV ). The measured height dependence of the linewidths is in good agreement with Stark coefficients calculated for the experimental shape variation. We attribute the microscopic source of fluctuating electric fields to the random motion of surface charges at the vacuum-semiconductor interface. Our results offer guidelines for creating frequency-locked photon sources, which will serve as key devices for long-distance quantum key distribution.

  7. Normal incidence X-ray telescope power spectra of X-ray emission from solar active regions. I - Observations. II - Theory

    NASA Technical Reports Server (NTRS)

    Gomez, Daniel O.; Martens, Petrus C. H.; Golub, Leon

    1993-01-01

    Fourier analysis is applied to very high resolution image of coronal active regions obtained by the Normal Incidence X-Ray Telescope is used to find a broad isotropic power-law spectrum of the spatial distribution of soft X-ray intensities. Magnetic structures of all sizes are present down to the resolution limit of the instrument. Power spectra for the X-ray intensities of a sample of topologically different active regions are found which fall off with increasing wavenumber as 1/k-cubed. A model is presented that relates the basic features of coronal magnetic fluctuations to the subphotospheric hydrodynamic turbulence that generates them. The model is used to find a theoretical power spectrum for the X-ray intensity which falls off with increasing wavenumber as 1/k-cubed. The implications of a turbulent regime in active regions are discussed.

  8. Estimation of the solvent reorganization energy and the absolute energy of solvation of charge-transfer states from their emission spectra.

    PubMed

    Solís, Claudia; Grosso, Viviana; Faggioli, Nathaniel; Cosa, Gonzalo; Romero, Mario; Previtali, Carlos; Montejano, Hernán; Chesta, Carlos

    2010-05-01

    We report herein the solvent and temperature effects on the emission of the intermolecular exciplexes 1-cyanonaphthalene/triethylamine and 1-methylnaphthalene/triethylamine and the intramolecular exciplexes formed by the bichromophoric compounds diethyl-(3-naphthalen-1-yl-propyl)-amine (I), diethyl-(2-naphthalen-1-yl-ethyl)-amine (II), 3-[ethyl-(2-naphthalen-1-yl-ethyl)-amino]-propionitrile (III) and 3-[(2-cyano-ethyl)-(2-naphthalen-1-yl-ethyl)-amino]-propionitrile (IV). The results are interpreted within the formalism of the semiclassical Marcus theory for radiative back electron transfer (BET) reactions. We show that, following a few simple assumptions, reliable values of the Gibbs free energy changes (DeltaG(epsilon)(-et)) and the solvent reorganization energies (lambda(epsilon)(s)) associated to the BET reactions (and their corresponding enthalpic and entropic contributions) can be estimated directly from the emission of the CT states. We also show that for the 1-cyanonaphthalene/triethylamine exciplex, which exhibits emission in the vapour phase, the experimental calculation of the absolute energy of solvation of the CT state (DeltaG(epsilon)(s)) is also possible. The calculated DeltaG(epsilon)(-et) correlate quite satisfactorily with the corresponding values obtained from independent electrochemical and kinetics experiments. The temperature effects on DeltaG(epsilon)(-et), lambda(epsilon)(s) and DeltaG(epsilon)(s) are discussed qualitatively using different solvation models. The limitations of the present approach for the estimation of DeltaG(epsilon)(-et) and lambda(epsilon)(s) and its possible application to more complex A/D systems are also examined. PMID:20442927

  9. Detection of Broad H$\\alpha$ Emission Lines in the Late-time Spectra of a Hydrogen-poor Superluminous Supernova

    E-print Network

    Yan, Lin; Ofek, E; Gal-Yam, A; Mazzali, P; Perley, D; Vreeswijk, P; Leloudas, G; de Cia, A; Masci, F; Cenko, S B; Cao, Y; Kulkarni, S R; Nugent, P E; Rebbapragada, Umaa D; Wo?niak, P R; Yaron, O

    2015-01-01

    iPTF13ehe is a hydrogen-poor superluminous supernova (SLSN) at z=0.3434, with properties similar to SN2007bi. It rises within (83-148)days (rest-frame) to reach a peak bolometric luminosity of 1.3x$10^{44}$erg/s, then decays very slowly at 0.015mag. per day. The measured ejecta velocity is 13000km/s. The inferred explosion characteristics, such as the ejecta mass (67-220$M_\\odot$), the total radiative and kinetic energy ($10^{51}$ & 2x$10^{53}$erg respectively), is typical of SLSN-R events. However, the late-time spectrum taken at +251days reveals a Balmer Halpha emission feature with broad and narrow components, which has never been detected before among other H-poor SLSNe. The broad component has a velocity width of ~4500km/s and has a ~300km/s blue-ward shift relative to the narrow component. We interpret this broad Halpha emission line as the interaction between the supernova ejecta and a H-rich circumstellar medium (CSM) shell, located at a distance of ~4x$10^{16}$cm from the explosion site. This eje...

  10. Theoretical spectra of terrestrial exoplanet surfaces

    E-print Network

    Hu, Renyu

    We investigate spectra of airless rocky exoplanets with a theoretical framework that self-consistently treats reflection and thermal emission. We find that a silicate surface on an exoplanet is spectroscopically detectable ...

  11. Co-spatial Long-slit UV/Optical AL Spectra of 10 Galactic Planetary Nebulae with HST/STIS. I. Description of the Observations, Global Emission-line Measurements, and CNO Abundances

    NASA Astrophysics Data System (ADS)

    Dufour, Reginald J.; Kwitter, Karen B.; Shaw, Richard A.; Henry, Richard B. C.; Balick, Bruce; Corradi, Romano L. M.

    2015-04-01

    We present observations and initial analysis from a Hubble Space Telescope (HST) Cycle 19 program using STIS to obtain the first co-spatial, UV-optical spectra of 10 Galactic planetary nebulae (PNs). Our primary objective was to measure the critical emission lines of carbon and nitrogen with unprecedented signal-to-noise ratio (S/N) and spatial resolution over the wavelength range 1150-10270 Å, with the ultimate goal of quantifying the production of these elements in low- and intermediate-mass stars. Our sample was selected from PNs with a near-solar metallicity, but spanning a broad range in N/O based on published ground-based and IUE spectra. This study, the first of a series, concentrates on the observations and emission-line measurements obtained by integrating along the entire spatial extent of the slit. We derived ionic and total elemental abundances for the seven PNs with the strongest UV line detections (IC 2165, IC 3568, NGC 2440, NGC 3242, NGC 5315, NGC 5882, and NGC 7662). We compare these new results with other recent studies of the nebulae and discuss the relative merits of deriving the total elemental abundances of C, N, and O using ionization correction factors (ICFs) versus summed abundances. For the seven PNs with the best UV line detections, we conclude that summed abundances from direct diagnostics of ions with measurable UV lines give the most accurate values for the total elemental abundances of C and N (although ICF abundances often produced good results for C). In some cases where significant discrepancies exist between our abundances and those from other studies, we show that the differences can often be attributed to their use of fluxes that are not co-spatial. Finally, we examined C/O and N/O versus O/H and He/H in well-observed Galactic, LMC, and SMC PNs and found that highly accurate abundances are essential for properly inferring elemental yields from their progenitor stars. Future papers will discuss photoionization modeling of our observations, of both the integrated spectra and spatial variations of the UV versus optical lines along the STIS slit lengths, which are unique to our observations. Based on observations with the NASA/ESA Hubble Space Telescope obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555.

  12. 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)

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

    2013-02-01

    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.

  13. Detailed non-LTE calculations of the iron emission from NGC 1068

    NASA Technical Reports Server (NTRS)

    Band, David L.; Klein, Richard I.; Castor, John I.; Nash, J. K.

    1989-01-01

    The X-ray iron line emission from NGC 1068 observed by the Ginga satellite is modeled using the new multiline, multilevel, non-LTE radiative transport code ALTAIR and a detailed atomic model for Ne-like through stripped iron. The parameter space of the obscured type 1 Seyfert nucleus model for this object is studied. The equivalent width is greater than previously predicted. It is found that detailed radiative transfer can have a significant effect on the observed line flux both for the K alpha line and for the L-shell emission. The ionization of the iron increases with temperature. Therefore the K alpha equivalent width and energy is a function not only of the ionization parameter, but also of the column depth and temperature. For a likely model of NGC 1068 it is found that the iron abundance is about twice solar, but that modifications of this model may permit a smaller abundance.

  14. Solar-wind Ion-driven X-Ray Emission from Cometary and Planetary Atmospheres: Measurements and Theoretical Predictions of Charge-Exchange Cross-sections and Emission Spectra for O6+ + H2O, Co, Co2, Ch4, N2, NO, N2O, and Ar

    NASA Astrophysics Data System (ADS)

    Machacek, J. R.; Mahapatra, D. P.; Schultz, D. R.; Ralchenko, Yu.; Moradmand, A.; El Ghazaly, M. O. A.; Chutjian, A.

    2015-08-01

    Relevant to modeling and understanding X-ray emission from cometary and planetary atmospheres, total cross-sections for 1.17 and 2.33 keV/u O6+ colliding with H2O, CO, CO2, CH4, N2, NO, N2O, and Ar have been measured for the processes of single, double, and triple charge exchanges. Using these measurements as benchmarks, synthetic emission spectra spanning the X-ray, UV, and visible range have been calculated based on theoretical treatment of the transfer of between one and six electrons from the target neutrals to the projectile ion, followed by radiative and non-radiative decay of the highly excited states produced in these collisions. The results help add to the base of knowledge required to simulate ion-neutral processes in astrophysical environments; refine the present understanding of these fundamental atomic processes; and guide future observations, laboratory measurements, and theoretical predictions.

  15. High K-alpha X-ray Conversion Efficiency From Extended Source Gas Jet Targets Irradiated by Ultra Short Laser Pulses

    SciTech Connect

    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

    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.

  16. A synchrotron self-Compton emission model compared with the VHE spectrum of Crab Nebula, Geminga energy spectra and hadronic gamma-rays in the Tycho SNR

    NASA Astrophysics Data System (ADS)

    Sinitsyna, V. G.; Borisov, S. S.; Musin, F. I.; Nikolsky, S. I.; Sinitsyna, V. Y.; Platonov, G. F.

    2009-12-01

    The Crab Nebula has an extraordinary broad spectrum, attributed to synchrotron radiation of electrons with energies from GeV to PeV. This continuous spectrum appears to terminate near 108 eV and photons, produced by relativistic electrons and positrons (˜1015 eV) via the Inverse Compton effect, form a new component of the spectrum in the GeV - TeV energy range. The spectrum of ?-rays from the Crab Nebula has been measured in the energy range 0.8 TeV to 11 TeV at the SHALON Alatoo Observatory by the atmospheric Cerenkov technique. The VHE spectral energy distribution of the Crab Nebula is compared with the predictions of a synchrotron self-Compton emission model in the energy range 0.8 TeV to 11 TeV (Hillas et al. 1998). Tycho's SNR has been observed by SHALON imaging Cherenkov telescope at Tien-Shan. This object, Ia SNR, has long been considered as a candidate for a CR hadron source in the Northern Hemisphere. The expected pion decay ?-flux, F˜E?-1, extends up to >30 TeV, whereas the IC ?-ray flux has a cutoff above a few TeV. So, the detection of ?-rays at energies of 10 - 40 TeV by SHALON is evidence for a hadron origin of the ?-rays.

  17. Photobleaching Response of Different Sources of Chromophoric Dissolved Organic Matter Exposed to Natural Solar Radiation Using Absorption and Excitation–Emission Matrix Spectra

    PubMed Central

    Zhang, Yunlin; Liu, Xiaohan; Osburn, Christopher L.; Wang, Mingzhu; Qin, Boqiang; Zhou, Yongqiang

    2013-01-01

    CDOM biogeochemical cycle is driven by several physical and biological processes such as river input, biogeneration and photobleaching that act as primary sinks and sources of CDOM. Watershed-derived allochthonous (WDA) and phytoplankton-derived autochthonous (PDA) CDOM were exposed to 9 days of natural solar radiation to assess the photobleaching response of different CDOM sources, using absorption and fluorescence (excitation-emission matrix) spectroscopy. Our results showed a marked decrease in total dissolved nitrogen (TDN) concentration under natural sunlight exposure for both WDA and PDA CDOM, indicating photoproduction of ammonium from TDN. In contrast, photobleaching caused a marked increase in total dissolved phosphorus (TDP) concentration for both WDA and PDA CDOM. Thus TDN?TDP ratios decreased significantly both for WDA and PDA CDOM, which partially explained the seasonal dynamic of TDN?TDP ratio in Lake Taihu. Photobleaching rate of CDOM absorption a(254), was 0.032 m/MJ for WDA CDOM and 0.051 m/MJ for PDA CDOM from days 0–9, indicating that phototransformations were initially more rapid for the newly produced CDOM from phytoplankton than for the river CDOM. Extrapolation of these values to the field indicated that 3.9%–5.1% CDOM at the water surface was photobleached and mineralized every day in summer in Lake Taihu. Photobleaching caused the increase of spectral slope, spectral slope ratio and molecular size, indicating the CDOM mean molecular weight decrease which was favorable to further microbial degradation of mineralization. Three fluorescent components were validated in parallel factor analysis models calculated separately for WDA and PDA CDOM. Our study suggests that the humic-like fluorescence materials could be rapidly and easily photobleached for WDA and PDA CDOM, but the protein-like fluorescence materials was not photobleached and even increased from the transformation of the humic-like fluorescence substance to the protein-like fluorescence substance. Photobleaching was an important driver of CDOM and nutrients biogeochemistry in lake water. PMID:24204852

  18. Storm Spectra

    NASA Technical Reports Server (NTRS)

    2007-01-01

    These images, taken with the LEISA infrared camera on the New Horizons Ralph instrument, show fine details in Jupiter's turbulent atmosphere using light that can only be seen using infrared sensors. These are 'false color' pictures made by assigning infrared wavelengths to the colors red, green and blue. LEISA (Linear Etalon Imaging Spectral Array) takes images across 250 IR wavelengths in the range from 1.25 to 2.5 microns, allowing scientists to obtain an infrared spectrum at every location on Jupiter. A micron is one millionth of a meter.

    These pictures were taken at 05:58 UT on February 27, 2007, from a distance of 2.9 million kilometers (1.6 million miles). They are centered at 8 degrees south, 32 degrees east in Jupiter 'System III' coordinates. The large oval-shaped feature is the well-known Great Red Spot. The resolution of each pixel in these images is about 175 kilometers (110 miles); Jupiter's diameter is approximately 145,000 kilometers (97,000 miles).

    The image on the left is an altitude map made by assigning the color red to 1.60 microns, green to 1.89 microns and blue to 2.04 microns. Because Jupiter's atmosphere absorbs light strongly at 2.04 microns, only clouds at very high altitude will reflect light at this wavelength. Light at 1.89 microns can go deeper in the atmosphere and light at 1.6 microns can go deeper still. In this map, bluish colors indicate high clouds and reddish colors indicate lower clouds. This picture shows, for example, that the Great Red Spot extends far up into the atmosphere.

    In the image at right, red equals 1.28 microns, green equals 1.30 microns and blue equals 1.36 microns, a range of wavelengths that similarly probes different altitudes in the atmosphere. This choice of wavelengths highlights Jupiter's high-altitude south polar hood of haze. The edge of Jupiter's disk at the bottom of the panel appears slightly non-circular because the left-hand portion is the true edge of the disk, while the right portion is defined by the day/night boundary (known as the terminator).

    These two images illustrate only a small fraction of the information contained in a single LEISA scan, highlighting just one aspect of the power of infrared spectra for atmospheric studies.

  19. C NMR Spectra C NMR Spectra

    E-print Network

    Collum, David B.

    S16 1 H and 13 C NMR Spectra (see p S3) Me N-i-Pr #12;S17 1 H and 13 C NMR Spectra (see p S3) Me NBn #12;S18 1 H and 13 C NMR Spectra (see p S4) NBn #12;S19 1 H and 13 C NMR Spectra (see p S4) NBn Me Me Me #12;S20 1 H and 13 C NMR Spectra (see p S4) N-n-Bu Me Me Me #12;S21 1 H and 13 C NMR Spectra

  20. Longitudinal mode spectra of diode lasers

    SciTech Connect

    Streifer, W.; Scifres, D.R.; Burnham, R.D.

    1982-02-15

    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.

  1. Cooling effect in emissions of 103mRh excited by bremsstrahlung

    E-print Network

    Yao Cheng; Bing Xia; Chinping Chen

    2009-04-29

    Nonlinear characteristic emissions of K alpha, K beta and gamma with a significant triplet splitting at room temperature are observed from the long-lived nuclear state of 103mRh excited by bremsstrahlung irradiation. A pronounced phase-transition-like narrowing of the emission profiles occurs immediately after the sample is cooled down to 77 K. The room temperature profiles reappear again abruptly and almost reversibly as the temperature drifts freely back to approximately the ice point after the filling of liquid nitrogen is stopped. These emission properties at 300 K and at low temperature may indicate that the 103mRh nuclei are in collective states.

  2. Mid-Infrared Spectra of Be Stars

    E-print Network

    S. A. Rinehart; J. R. Houck; J. D. Smith

    1999-10-11

    We present the first medium-resolution ($R\\sim 600$) mid-infrared (8-13.3\\micron) spectra of 11 Be stars. A large number of lines are observed and identified in these spectra, including, as an example, 39 hydrogen recombination lines in the spectrum of $\\gamma$ Cas. In the majority of our spectra, all of the observed lines are attributable to hydrogen recombination. Two of the sources, $\\beta$ Lyr and MWC 349 also show emission from other species. Both of these objects show evidence of [Ne II] emission, and $\\beta$ Lyr also shows evidence of He I emission. We tabulate the effective line strength and line widths for the observed lines, and briefly discuss the physical implications of the observed line series. We also use a simple model of free-free emission to characterize the disks around these sources.

  3. 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...

  4. Infrared reflectance spectra (4-12 micron) of lunar samples

    NASA Technical Reports Server (NTRS)

    Nash, Douglas B.

    1991-01-01

    Presented here are infrared reflectance spectra of a typical set of Apollo samples to illustrate spectral character in the mid-infrared (4 to 12 microns) of lunar materials and how the spectra varies among three main forms: soil, breccia, and igneous rocks. Reflectance data, to a close approximation, are the inverse of emission spectra; thus, for a given material the spectral reflectance (R) at any given wavelength is related to emission (E) by 1 - R equals E. Therefore, one can use reflectance spectra of lunar samples to predict how emission spectra of material on the lunar surface will appear to spectrometers on orbiting spacecraft or earthbound telescopes. Spectra were measured in the lab in dry air using a Fourier Transform Infrared spectrometer. Shown here is only the key portion (4 to 12 microns) of each spectrum relating to the principal spectral emission region for sunlit lunar materials and to where the most diagnostic spectral features occur.

  5. K{beta} spectra of heliumlike iron from TFTR plasmas

    SciTech Connect

    Smith, A.J.; Bitter, M.; Hsuan, H.; Hill, K.W.; von Goeler, S.; Timberlake, J.; Beiersdorfer, P.; Osterheld, A.

    1992-12-01

    K{beta} spectra of helium-like iron, Fe XXV, have been observed from TFTR plasmas with a high-resolution crystal spectrometer. The wavelength range of the Fe K{beta} spectrum partially overlaps the spectrum of helium-like nickel (Ni XXVII), which is used on TFTR and JET for ion temperature measurements. The experimental arrangement made it possible to observe the Fe XXV K{beta} lines and their satellite transitions of the type 1s2l{prime}31{double_prime} {yields} 1s{sup 2}21{prime}, as well as the entire satellite spectrum of the Ni XXVII K {alpha} line simultaneously. In order to identify the features of the K{beta} spectra and to study their possible interference with the Ni XXVII spectrum, the intensity of the K{beta} spectrum was enhanced by injection of iron into the plasma. Accurate wavelengths and intensities have been obtained and compared with different theoretical calculations.

  6. K[beta] spectra of heliumlike iron from TFTR plasmas

    SciTech Connect

    Smith, A.J. ); Bitter, M.; Hsuan, H.; Hill, K.W.; von Goeler, S.; Timberlake, J. . Plasma Physics Lab.); Beiersdorfer, P.; Osterheld, A. )

    1992-12-01

    K[beta] spectra of helium-like iron, Fe XXV, have been observed from TFTR plasmas with a high-resolution crystal spectrometer. The wavelength range of the Fe K[beta] spectrum partially overlaps the spectrum of helium-like nickel (Ni XXVII), which is used on TFTR and JET for ion temperature measurements. The experimental arrangement made it possible to observe the Fe XXV K[beta] lines and their satellite transitions of the type 1s2l[prime]31[double prime] [yields] 1s[sup 2]21[prime], as well as the entire satellite spectrum of the Ni XXVII K [alpha] line simultaneously. In order to identify the features of the K[beta] spectra and to study their possible interference with the Ni XXVII spectrum, the intensity of the K[beta] spectrum was enhanced by injection of iron into the plasma. Accurate wavelengths and intensities have been obtained and compared with different theoretical calculations.

  7. Digital filtering of plume emission spectra

    NASA Technical Reports Server (NTRS)

    Madzsar, George C.

    1990-01-01

    Fourier transformation and digital filtering techniques were used to separate the superpositioned spectral phenomena observed in the exhaust plumes of liquid propellant rocket engines. Space shuttle main engine (SSME) spectral data were used to show that extraction of spectral lines in the spatial frequency domain does not introduce error, and extraction of the background continuum introduces only minimal error. Error introduced during band extraction could not be quantified due to poor spectrometer resolution. Based on the atomic and molecular species found in the SSME plume, it was determined that spectrometer resolution must be 0.03 nm for SSME plume spectral monitoring.

  8. The Theory of Spectra and Atomic Constitution

    NASA Astrophysics Data System (ADS)

    Bohr, Niels

    2011-06-01

    Part I. On the Spectrum of Hydrogen: 1. Empirical spectral laws; 2. Laws of temperature radiation; 3. The nuclear theory of the atom; 4. Quantum theory of spectra; 5. Hydrogen spectrum; 6. The Pickering lines; 7. Other spectra; Part II. On the Series Spectra of the Elements; Section 1. Introduction; Section 2. General Principles of the Quantum Theory of Spectra: 8. Hydrogen spectrum; 9. The correspondence principle; 10. General spectral laws; 11. Absorption and excitation of radiation; Section 3. Development of the Quantum Theory of Spectra: 12. Effect of external forces on the hydrogen spectrum; 13. The Stark effect; 14. The Zoeman effect; 15. Central pertubations; 16. Relativity effect of hydrogen lines; 17. Theory of series spectra; 18. Correspondence principle and conservation of angular momentum; 19. The spectra of helium and lithium; 20. Complex structure of series lines; Section 4. Conclusion; Part III. The Structure of the Atom and the Physical and Chemical Properties of the Elements; Section 5. Preliminary: 21. The nuclear atom; 22. The postulates of the quantum theory; 23. Hydrogen atom; 24. Hydrogen spectrum and x-ray spectra; 25. The fine structure of the hydrogen lines; 26. Periodic table; 27. Recent atomic models; Section 6. Series Spectra and the Capture of Electrons by Atoms: 28. Arc and spark spectra; 29. Series diagram; 30. Correspondence principle; Section 7. Formation of Atoms and the Periodic Table: 31. First period. Hydrogen-helium; 32. Second period. Lithium-neon; 33. Third period. Sodium-argon; 34. Fourth period. Potassium-Krypton; 35. Fifth period. Rubidium-xenon; 36. Sixth period. Caesium-niton; 37. Seventh period; 38. Survey of the periodic table; Section 8. Reorganization of Atoms and X-Ray SPectra: 39. Absorption and emission of x-rays and correspondence principle; 40. X-ray spectra and atomic structure; 41. Classification of x-ray spectra; 42. Conclusion; Appendix.

  9. Night Spectra Quest.

    ERIC Educational Resources Information Center

    Jacobs, Stephen

    1995-01-01

    Presents the Night Spectra Quest, a pocket-sized chart that identifies in color the spectra of all the common night lights and has an integrally mounted, holographic diffraction grating to look through. (JRH)

  10. K-Shell Diagram and Hypersatellite Spectra of 4D Transition Elements

    SciTech Connect

    Diamant, R.; Kao, C.; Huotari, S.; Hamalainen, K.; Sharon, R.; Honkimaki, V.; Buslaps, T.; Deutsch, M.

    2009-07-25

    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.

  11. IUE spectra of flares on AU Mic

    NASA Technical Reports Server (NTRS)

    Butler, C. J.; ion lines and optical continuum.

    1986-01-01

    Some IUE spectra were obtained in August 1980 through a substantial part of the optical cycle of the BY Draconis-type, spotted M dwarf star, AU Mic. No modulation of the ultraviolet emission line fluxes in antiphase with the optical curve is detected. Simultaneous optical photometry of AU Mic shows remarkably poor correlation of optical flare strength and ultraviolet emission-line enhancements. The flares detected on AU Mic show considerable variety in the degree of enhancement in the various emission lines and optical continuum.

  12. Crack spectra analysis

    SciTech Connect

    Tiernan, M.

    1980-09-01

    Crack spectra derived from velocity data have been shown to exhibit systematics which reflect microstructural and textural differences between samples (Warren and Tiernan, 1980). Further research into both properties and information content of crack spectra have yielded the following: Spectral features are reproducible even at low pressures; certain observed spectral features may correspond to non-in-situ crack populations created during sample retrieval; the functional form of a crack spectra may be diagnostic of the sample's grain texture; hysteresis is observed in crack spectra between up and down pressure runs - it may be due to friction between the faces of closed crack populations.

  13. Resonant Compton scattering and gamma-ray burst continuum spectra

    NASA Technical Reports Server (NTRS)

    Baring, M. G.

    1995-01-01

    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.

  14. Characteristics of energetic solar flare electron spectra

    NASA Technical Reports Server (NTRS)

    Moses, Dan; Droege, Wolfgang; Meyer, Peter; Evenson, Paul

    1989-01-01

    A 55 event survey of energy spectra of 0.1-100 MeV interplanetary electrons originating from solar flares as measured by two spectrometers onboard the ISEE 3 (ICE) spacecraft for the years 1978-1982 has been completed. Spectra generated using the maximum flux of a given event in each energy channel were restricted to events with a well-defined flux rise time. Two broad groups of electron spectra are considered. In one group, the spectra are well represented by a single power law in rigidity with spectral index in the range 3-4.5. The spectra in the other group deviate from a power law in rigidity systematically in that they harden with increasing rigidity. Events with near power-law spectra are found to be correlated with long-duration soft X-ray events, whereas those with hardening spectra are correlated with short-duration events. The possible variation of acceleration and propagation processes with the properties of the flare site is discussed, using the duration of the soft X-ray flare emission as an indicator of the physical parameters of the flare site (flare volume, density, coronal height, and magnetic field geometry).

  15. Auroral electron spectra. [differential energy spectra

    NASA Technical Reports Server (NTRS)

    Rees, M. H.; Maeda, K.

    1973-01-01

    Discussion of the suitability of available differential electron flux data for auroral analyses. The differential energy spectra of auroral electrons at several altitudes computed by Berger et al. (1973) and Rees and Jones (1973) for initial electron energies of 10, 5, and 2 keV are reviewed, and it is concluded that they are suitable for auroral analyses.

  16. Catalogue of representative meteor spectra

    NASA Astrophysics Data System (ADS)

    Vojá?ek, V.; Borovi?ka, J.; Koten, P.; Spurný, P.; Štork, R.

    2015-08-01

    Aims: We present a library of low-resolution meteor spectra that includes sporadic meteors, members of minor meteor showers, and major meteor showers. These meteors are in the magnitude range from +2 to -3, corresponding to meteoroid sizes from 1 mm to 10 mm. Methods: Parallel double-station video observations allowed us to compute heliocentric orbits for all meteors. Most observations were performed during the periods of activity of major meteor showers in the years between 2006 and 2012. Spectra are classified according to relative intensities of the low-temperature emission lines of Mg, Na, and Fe. Results: Shower meteors were found to be of normal composition, except for Southern ? Aquariids and some members of the Geminid shower, neither of which have Na in the meteor spectra. Variations in Na content are typical for the Geminid shower. Three populations of Na-free mereoroids were identified. The first population are iron meteorites, which have an asteroidal-chondritic origin, but one meteoroid with low perihelion (0.11 AU) was found among the iron meteorites. The second population were Sun-approaching meteoroids in which sodium is depleted by thermal desorption. The third population were Na-free meteoroids of cometary origin. Long exposure to cosmic rays on the surface of comets in the Oort cloud and disintegration of this crust might be the origin of this population of meteoroids. Spectra (Figs. 17-30) are only, Tables 4-6 are also available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/580/A67

  17. Elevated temperature reference spectra

    SciTech Connect

    Brown, D.; Phillips, B.; Tussey, L.

    1997-12-31

    A compilation of infrared spectra at elevated temperatures is required for the accurate quantification of gas concentrations for Fourier transform infrared (FTIR) extractive sampling of stack gases and FTIR in-situ process monitoring. Analysis of high temperature gases utilizing ambient temperature reference spectra can result in significant quantification errors. The US Air Force`s Arnold Engineering Development Center (AEDC) is currently assisting the EPA in measuring reference spectra and making existing and new data available to the public through two ongoing efforts. One of these efforts is the measurement of elevated temperature infrared reference spectra of the low vapor pressure hazardous air pollutants (HAP) compounds, as well as spectral interfering compounds. The equipment and procedures used for the elevated temperature reference spectra measurements is described as well as some of the challenges encountered in these measurements. Examples of the reference spectra are also presented. To make the reference spectra developed by AEDC and other EPA programs easily accessible, AEDC has also been tasked to maintain a site on the World Wide Web containing reference spectra, reports, and software tools of interest to the optical sensing community. This web site has seen increased use during the three years that it has been in existence with users from academia, commercial, and government, both domestic and foreign. The site has undergone several improvements since inception and actively solicits inputs for further improvements from its users. A description of this web site and recent improvements and additions is given in this paper.

  18. Algorithms for classification of astronomical object spectra

    NASA Astrophysics Data System (ADS)

    Wasiewicz, P.; Szuppe, J.; Hryniewicz, K.

    2015-09-01

    Obtaining interesting celestial objects from tens of thousands or even millions of recorded optical-ultraviolet spectra depends not only on the data quality but also on the accuracy of spectra decomposition. Additionally rapidly growing data volumes demands higher computing power and/or more efficient algorithms implementations. In this paper we speed up the process of substracting iron transitions and fitting Gaussian functions to emission peaks utilising C++ and OpenCL methods together with the NOSQL database. In this paper we implemented typical astronomical methods of detecting peaks in comparison to our previous hybrid methods implemented with CUDA.

  19. Signatures of hot electrons and fluorescence in Mo K? emission on Z

    SciTech Connect

    Hansen, S. B.; Ampleford, D. J.; Cuneo, M. E.; Jones, B.; Jennings, C. A.; Coverdale, C. A.; Rochau, G. A.; Dunham, G.; Ouart, N.; Dasgupta, A.; Giuliani, J. L.; Apruzese, J. P.

    2014-03-15

    Recent experiments on the Z accelerator have produced high-energy (17?keV) inner-shell K-alpha emission from molybdenum wire array z-pinches. Extensive absolute power and spectroscopic diagnostics along with collisional-radiative modeling enable detailed investigation into the roles of thermal, hot electron, and fluorescence processes in the production of high-energy x-rays. We show that changing the dimensions of the arrays can impact the proportion of thermal and non-thermal K-shell x-rays.

  20. Low energy X-ray spectra measured with a mercuric iodide energy dispersive spectrometer in a scanning electron microscope

    NASA Technical Reports Server (NTRS)

    Iwanczyk, J. S.; Dabrowski, A. J.; Huth, G. C.; Bradley, J. G.; Conley, J. M.

    1986-01-01

    A mercuric iodide energy dispersive X-ray spectrometer, with Peltier cooling provided for the detector and input field effect transistor, has been developed and tested in a scanning electron microscope. X-ray spectra were obtained with the 15 keV electron beam. An energy resolution of 225 eV (FWHM) for Mn-K(alpha) at 5.9 keV and 195 eV (FWHM) for the Mg-K line at 1.25 keV has been measured. Overall system noise level was 175 eV (FWHM). The detector system characterization with a carbon target demonstrated good energy sensitivity at low energies and lack of significant spectral artifacts at higher energies.

  1. Thermodynamic analysis of spectra

    NASA Astrophysics Data System (ADS)

    Mitchell, G. E.; Shriner, J. F.

    2008-04-01

    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 ?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 ?3, and thus the internal energy can serve as a addition to the tool kit for evaluating experimental spectra.

  2. Discriminating the Progenitor Type of Supernova Remnants with Iron K-Shell Emission

    NASA Technical Reports Server (NTRS)

    Yamaguchi, Hiroya; Badenes, Carles; Petre, Robert; Nakano, Toshio; Castro, Daniel; Enoto, Teruaki; Hiraga, Junko S.; Hughes, John P.; Maeda, Yoshitomo; Nobukawa, Masayoshi

    2014-01-01

    Supernova remnants (SNRs) retain crucial information about both their parent explosion and circumstellar material left behind by their progenitor. However, the complexity of the interaction between supernova ejecta and ambient medium often blurs this information, and it is not uncommon for the basic progenitor type (Ia or core-collapse) of well-studied remnants to remain uncertain. Here we present a powerful new observational diagnostic to discriminate between progenitor types and constrain the ambient medium density of SNRs using solely Fe K-shell X-ray emission. We analyze all extant Suzaku observations of SNRs and detect Fe K-alpha emission from 23 young or middle-aged remnants, including five first detections (IC 443, G292.0+1.8, G337.2-0.7, N49, and N63A). The Fe K-alpha centroids clearly separate progenitor types, with the Fe-rich ejecta in Type Ia remnants being significantly less ionized than in core-collapse SNRs. Within each progenitor group, the Fe K-alpha luminosity and centroid are well correlated, with more luminous objects having more highly ionized Fe. Our results indicate that there is a strong connection between explosion type and ambient medium density, and suggest that Type Ia supernova progenitors do not substantially modify their surroundings at radii of up to several parsecs. We also detect a K-shell radiative recombination continuum of Fe in W49B and IC 443, implying a strong circumstellar interaction in the early evolutionary phases of these core-collapse remnants.

  3. High-energy thermal synchrotron emission

    NASA Technical Reports Server (NTRS)

    Imamura, J. N.; Epstein, R. I.; Petrosian, V.

    1985-01-01

    It is shown how the thermal synchrotron emission spectrum is modified when the photon energy is greater than the mean energy of the radiating particles. The effect if applying this energy conservation constraint is to produce spectra which have less high-energy photon emission than had been previously estimated. The thermal synchrotron spectra provide satisfactory fits to recently observed very high energy gamma ray spectra of certain burst sources.

  4. Disk-averaged synthetic spectra of Mars

    NASA Technical Reports Server (NTRS)

    Tinetti, Giovanna; Meadows, Victoria S.; Crisp, David; Fong, William; Velusamy, Thangasamy; Snively, Heather

    2005-01-01

    The principal goal of the NASA Terrestrial Planet Finder (TPF) and European Space Agency's Darwin mission concepts is to directly detect and characterize extrasolar terrestrial (Earthsized) planets. This first generation of instruments is expected to provide disk-averaged spectra with modest spectral resolution and signal-to-noise. Here we use a spatially and spectrally resolved model of a Mars-like planet to study the detectability of a planet's surface and atmospheric properties from disk-averaged spectra. We explore the detectability as a function of spectral resolution and wavelength range, for both the proposed visible coronograph (TPFC) and mid-infrared interferometer (TPF-I/Darwin) architectures. At the core of our model is a spectrum-resolving (line-by-line) atmospheric/surface radiative transfer model. This model uses observational data as input to generate a database of spatially resolved synthetic spectra for a range of illumination conditions and viewing geometries. The model was validated against spectra recorded by the Mars Global Surveyor-Thermal Emission Spectrometer and the Mariner 9-Infrared Interferometer Spectrometer. Results presented here include disk-averaged synthetic spectra, light curves, and the spectral variability at visible and mid-infrared wavelengths for Mars as a function of viewing angle, illumination, and season. We also considered the differences in the spectral appearance of an increasingly ice-covered Mars, as a function of spectral resolution, signal-to-noise and integration time for both TPF-C and TPFI/ Darwin.

  5. Atomic Spectra Database (ASD)

    National Institute of Standards and Technology Data Gateway

    SRD 78 NIST Atomic Spectra Database (ASD) (Web, free access)   This database provides access and search capability for NIST critically evaluated data on atomic energy levels, wavelengths, and transition probabilities that are reasonably up-to-date. The NIST Atomic Spectroscopy Data Center has carried out these critical compilations.

  6. Cassini UVIS observations of Titan nightglow spectra

    NASA Astrophysics Data System (ADS)

    Ajello, Joseph M.; West, Robert A.; Gustin, Jacques; Larsen, Kristopher; Stewart, A. Ian F.; Esposito, Larry W.; McClintock, William E.; Holsclaw, Gregory M.; Bradley, E. Todd

    2012-12-01

    In this paper we present the first nightside EUV and FUV airglow limb spectra of Titan showing molecular emissions. The Cassini Ultraviolet Imaging Spectrograph (UVIS) observed photon emissions of Titan's day and night limb-airglow and disk-airglow on multiple occasions, including during an eclipse observation. The 71 airglow observations analyzed in this paper show EUV (600-1150 Å) and FUV (1150-1900 Å) atomic multiplet lines and band emissions arising from either photoelectron induced fluorescence and solar photo-fragmentation of molecular nitrogen (N2) or excitation by magnetosphere plasma. The altitude of the peak UV emissions on the limb during daylight occurred inside the thermosphere at the altitude of the topside ionosphere (near 1000 km altitude). However, at night on the limb, a subset of emission features, much weaker in intensity, arise in the atmosphere with two different geometries. First, there is a twilight photoelectron-excited glow that persists with solar depression angle up to 25-30 degrees past the terminator, until the solar XUV shadow height passes the altitude of the topside ionosphere (1000-1200 km). The UV twilight glow spectrum is similar to the dayglow but weaker in intensity. Second, beyond 120° solar zenith angle, when the upper atmosphere of Titan is in total XUV darkness, there is indication of weak and sporadic nightside UV airglow emissions excited by magnetosphere plasma collisions with ambient thermosphere gas, with similar N2 excited features as above in the daylight or twilight glow over an extended altitude range.

  7. The diversity of soft X-ray spectra in quasars

    NASA Technical Reports Server (NTRS)

    Elvis, M.; Wilkes, B. J.; Tananbaum, H.

    1985-01-01

    Soft X-ray spectra for three quasars obtained with the Einstein Imaging Proportional Counter covering the 0.1-4.0 keV band are reported. Power-law fits to these spectra have best-fit energy indices of 1.2 +0.6 or -0.2, for the quasar NAB 0205 + 024, 0.6 +0.3 or -0.2 for the quasar B2 1028 + 313, and 2.2 + or -0.4 for the quasar PG 1211 + 143. None of the quasars shows any evidence for a column density of cold matter in excess of the galactic values. The derived spectra demonstrate that there is no single universal power law slope for quasar X-ray spectra. The implications of these results for the X-ray background, X-ray continuum emission mechanisms, and the production of the optical/UV emission lines are briefly discussed.

  8. Observed Barium Emission Rates

    NASA Technical Reports Server (NTRS)

    Stenbaek-Nielsen, H. C.; Wescott, E. M.; Hallinan, T. J.

    1993-01-01

    The barium releases from the CRRES satellite have provided an opportunity for verifying theoretically calculated barium ion and neutral emission rates. Spectra of the five Caribbean releases in the summer of 1991 were taken with a spectrograph on board a U.S. Air Force jet aircraft. Because the line of sight release densities are not known, only relative rates could be obtained. The observed relative rates agree well with the theoretically calculated rates and, together with other observations, confirm the earlier detailed theoretical emission rates. The calculated emission rates can thus with good accuracy be used with photometric observations. It has been postulated that charge exchange between neutral barium and oxygen ions represents a significant source for ionization. If so. it should be associated with emissions at 4957.15 A and 5013.00 A, but these emissions were not detected.

  9. A rapid technique for classifying phytoplankton fluorescence spectra based on self-organizing maps.

    PubMed

    Aymerich, Ismael F; Piera, Jaume; Soria-Frisch, Aureli; Cros, Lluïsa

    2009-06-01

    Fluorescence spectroscopy has been demonstrated to be a powerful tool for characterizing phytoplankton communities in marine environments. Using different fluorescence spectra techniques, it is now possible to discriminate the major phytoplankton groups. However, most of the current techniques are based on fluorescence excitation measurements, which require stimulation at different wavelengths and thus considerable time to obtain the complete spectral profile. This requirement may be an important constraint for several mobile oceanographic platforms, such as vertical profilers or autonomous underwater vehicles, which require rapid-acquisition instruments. This paper presents a novel technique for classifying fluorescence spectra based on self-organizing maps (SOMs), one of the most popular artificial neural network (ANN) methods. The method is able to achieve phytoplankton discrimination using only fluorescence emission spectra (single wavelength excitation), thus reducing the acquisition time. The discrimination capabilities of SOM using excitation and emission spectra are compared. The analysis shows that the SOM has a good performance using excitation spectra, whereas data preprocessing is required in order to obtain similar discrimination capabilities using emission spectra. The final results obtained using emission spectra indicate that the discrimination is properly achieved even between algal groups, such as diatoms and dinoflagellates, which cannot be discriminated with previous methods. We finally point out that although techniques based on excitation spectra can achieve a better taxonomic accuracy, there are some applications that require faster acquisition processes. Acquiring emission spectra is almost instantaneous, and techniques such as SOM can achieve good classification performance using appropriately preprocessed data. PMID:19531300

  10. Pluto and Charon's UV spectra from IUE to New Horizons

    NASA Astrophysics Data System (ADS)

    Schindhelm, Eric; Stern, S. Alan; Gladstone, Randy; Zangari, Amanda

    2015-01-01

    We compare Mid-Ultraviolet (MUV) spectra of Pluto taken over a period of 20 years by the International Ultraviolet Explorer, the HST-Faint Object Spectrograph, and the HST-Cosmic Origins Spectrograph. We extract Pluto-only spectra from the IUE data and associate them with corrected longitudes when necessary. Comparing them with HST spectra provides further evidence of temporal changes in Pluto's geometric albedo between 2000 and 3200 Å. These various spectra are used to explore the contributions of atmospheric or surface changes to Pluto's reflectance. We also provide predictions for the Far-Ultraviolet (FUV) surface reflectance and atmospheric emission spectra of Pluto that will be measured by the Alice spectrograph (Stern, S.A. et al. [2008]. Space Sci. Rev. 140, 155-187) during the New Horizons flyby of Pluto in 2015. FUV surface reflectance predictions are also made for Charon, Hydra, and Nix.

  11. The angular power spectra of polarized Galactic synchrotron

    E-print Network

    M. Tucci; E. Carretti; S. Cecchini; R. Fabbri; M. Orsini; E. Pierpaoli

    2000-06-27

    We derive the angular power spectra of intensity and polarization of Galactic synchrotron emission in the range 36 < l < 10^3 from the Parkes survey mapping the southern Galactic plane at 2.4 GHz. The polarization spectra of both electric and magnetic parity up to l \\simeq 10^3 are approximated very well by power laws with slope coefficients \\simeq 1.4, quite different from the CMB spectra. We show that no problem should arise from Galactic synchrotron for measurements of CMB polarization in the cosmological window.

  12. [Fluorescence spectra analysis of the scrophularia soup].

    PubMed

    Yan, Li-hua; Song, Feng; Han, Juan; Su, Jing; Qu, Fei-fei; Song, Yi-zhan; Hu, Bo-lin; Tian, Jian-guo

    2008-08-01

    The cold-water and boiled-water soaked scrophularia soups have been prepared. The emission and excitation spectra of each scrophularia soup under different conditions have been measured at room temperature. The pH values of the different scrophularia soups have been also detected. There are obvious differences between the cold-water soaked scrophularia soup and the boiled-water soaked scrophularia. For both soups the emission wavelength increases with the wavelength of the excitation, but the peaks of the emission spectra for cold-water and boiled-water soaked scrophularia soup are different, which are 441 and 532 nm, respectively. Excitation spectrum has double peaks in the cold-water soaked scrophularia soup while only one peak with longer wavelength in the boiled-water soaked one. The pH value changes from 5.5 to 4.1. According to the organic admixture fluorescence mechanism we analyzed the reasons of the experimental results. Through heating, the interaction in different fluorescence molecular and the energy transfer process in the same fluorescence molecular become more active, and the conjugate structures and the generation of hydrogen bonds, increase. The fluorescence measurement is of value for the scrophularia pharmacology analysis and provides an analytical method for the quality identification of scrophularia soup. PMID:18975827

  13. Curved Radio Spectra of Weak Cluster Shocks

    E-print Network

    Kang, Hyesung

    2015-01-01

    We explore a diffusive shock acceleration (DSA) model for radio relics in which a spherical shock impinges on a magnetized cloud of fossil relativistic electrons in the cluster periphery. Such a scenario could explain uniformity of the surface brightness and spectral curvature in the integrated spectra of thin arc-like radio relics. Toward this end, we perform DSA simulations of spherical shocks with the parameters relevant for the Sausage radio relic in cluster CIZA J2242.8+5301, and calculate the ensuing radio synchrotron emission from re-accelerated electrons. The surface brightness profile of radio-emitting postshock region and the volume-integrated radio spectrum are calculated as well. We find that the observed width of the Sausage relic can be explained reasonably well by shocks with speed $u_s \\sim 3,000 \\kms$ and sonic Mach number $M_s \\sim 3$. These shocks produce curved radio spectra that steepen gradually over $(0.1-10) \

  14. Quasar Composite Spectra With BOSS

    NASA Astrophysics Data System (ADS)

    Harris, David; Dawson, K. S.; Myers, A. D.

    2013-06-01

    The Baryon Oscillation Spectroscopic Survey (BOSS) has collected over 100,000 $z>2$ quasar spectra since 2009. Using this unprecedented sample, we have created a composite spectrum at a signal-to-noise ratio of well over 500 per pixel. Using subsamples of BOSS spectra, we have also generated composite quasar spectra binned by luminosity and redshift. We present an analysis of quasar evolution, systematic lineshifts with luminosity, and line equivalent widths from these composite spectra.

  15. High-resolution 18 cm spectra of OH/IR stars

    NASA Technical Reports Server (NTRS)

    Fix, John D.

    1987-01-01

    High-velocity-resolution, high-signal-to-noise spectra have been obtained for the 18 cm maser emission lines from a number of optically visible OH/IR stars. The spectra have been interpreted in terms of a recent model by Alcock and Ross (1986), in which OH/IR stars lose mass in discrete elements rather than by a continuous wind. Comparison of the observed spectra with synthetic spectra shows that the lines are the composite emission from thousands or tens of thousands of individual elements.

  16. Theoretical Studies of Molecular Spectra

    NASA Technical Reports Server (NTRS)

    McKay, Christopher (Technical Monitor); Freedman, Richard S.

    2002-01-01

    This summary describes the research activities of the principal investigator during the reporting period. The research includes spectroscopy, management of molecular databases, and generation of spectral line profiles and opacity data. The spectroscopy research includes oxygen broadening of nitric oxide (NO), analysis of CO2 spectra, analysis of HNO3 spectra, and analysis of CO spectra.

  17. AKN 564: An Unusual Component in the X-ray Spectra of NLSy1 Galaxies

    NASA Technical Reports Server (NTRS)

    Turner, T. J.; George, I. M.; Netzer, Hagai

    1999-01-01

    We present an ASCA observation of the narrow-line Seyfert l (NLSyl) Arakelian 564. The X-ray light curve shows rapid variability, but no evidence for energy-dependence to these variations, within the 0.6 - 10 keV bandpass. A strong (EW approximately 70 eV) spectral feature is observed close to 1 keV. A similar feature has been observed in TON S180, another member of the NLSyl class of objects, but has not been observed in broad-line Seyfert galaxies. The feature energy suggests a large contribution from Fe L-shell lines but its intensity is difficult to explain in terms of emission and/or absorption from photoionized gas. The models which predict most emission at 1 keV are characterized by extreme values of column density, Fe abundance and ionization parameter. Models based on gas in thermal equilibrium with kT approximately l keV provide an alternative parameterization of the soft spectrum. The latter may be interpreted as the hot intercloud medium, undergoing rapid cooling and producing strong Fe L-shell recombination lines. In all cases the physical conditions are rather different from those observed in broad-line Seyferts. The hard X-ray spectrum shows a broad and asymmetric Fe K(alpha) line of large equivalent width (approximately 550 eV) suggestive of significant emission from the inner accretion disk. The profile can be explained by a neutral disk viewed at approximately 60 deg to the line-of-sight, contrary to the hypothesis that NLSyls are viewed pole-on. The large EW of this line, the strong 1 keV emission and the strong optical Fe emission lines all suggest an extreme Fe abundance in this and perhaps other NLSyls.

  18. HEAO 1 observations of X-ray emission from flares on dMe stars

    NASA Technical Reports Server (NTRS)

    Kahn, S. M.; Mason, K. O.; Bowyer, C. S.; Linsky, J. L.; Haisch, B. M.; White, N. E.; Pravdo, S. H.

    1979-01-01

    The paper reports the detection of two X-ray flares from each of the nearby dMe stars, AT Mic and AD Leo, with the A-2 experiment on board HEAO 1. A spectrum obtained during the brighter AT Mic flare, the first X-ray spectrum of a stellar flare, is well matched by a thermal model with a temperature 3 x 10 to the 7 K and an iron K-alpha emission line. The X-ray luminosities derived are in the range 1.3-16 x 10 to the 30th ergs/s, while emission measures are in the range 1.1-14 x 10 to the 53rd/cu cm. The estimated Lx/Lopt ratios exceed unity and are inconsistent with Mullan's flare model. Several scenarios to explain this discrepancy are proposed.

  19. IONIZED REFLECTION SPECTRA FROM ACCRETION DISKS ILLUMINATED BY X-RAY PULSARS

    SciTech Connect

    Ballantyne, D. R.; Purvis, J. D.; Strausbaugh, R. G.; Hickox, R. C.

    2012-03-10

    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.

  20. Using fe II Spectra to Trace the Metallicity

    NASA Astrophysics Data System (ADS)

    Verner, Ekaterina M.

    I would like to present new FeII emission model and the results on tracing metallicity with Fe II spectra using Galactic sources (e.g. Eta Carinae and RR Telescopii) and show how the connection with the Universe at high reshifts.

  1. EUV spectra from highly charged terbium ions in optically thin and thick plasmas

    NASA Astrophysics Data System (ADS)

    Suzuki, C.; Koike, F.; Murakami, I.; Tamura, N.; Sudo, S.; Long, E.; Sheil, J.; White, E.; O'Reilly, F.; Sokell, E.; Dunne, P.; O'Sullivan, G.

    2015-01-01

    We have observed extreme ultraviolet (EUV) spectra from terbium (Tb) ions in optically thin and thick plasmas for a comparative study. The experimental spectra are recorded in optically thin, magnetically confined torus plasmas and dense laser-produced plasmas (LPPs). The main feature of the spectra is quasicontinuum emission with a peak around 6.5-6.6 nm, the bandwidth of which is narrower in the torus plasmas than in the LPPs. A comparison between the two types of spectra also suggests strong opacity effects in the LPPs. A comparison with the calculated line strength distributions gives a qualitative interpretation of the observed spectra.

  2. An analysis of scattered light in low dispersion IUE spectra

    NASA Technical Reports Server (NTRS)

    Basri, G.; Clarke, J. T.; Haisch, B. M.

    1985-01-01

    A detailed numerical simulation of light scattering from the low-resolution grating in the short wavelength spectrograph of the IUE Observatory was developed, in order to quantitatively analyze the effects of scattering on both continuum and line emission spectra. It is found that: (1) the redistribution of light by grating scattering did not appreciably alter either the shape or the absolute flux level of continuum spectra for A-F stars; (2) late-type stellar continua showed a tendency to flatten when observed in scattered light toward the shorter wavelengths; and (3) the effect of grating scattering on emission lines is to decrease measured line intensities by an increasing percentage toward the shorter wavelengths. The spectra obtained from scattering experiments for solar-type and late type stars are reproduced in graphic form.

  3. Quantum optimal control of photoelectron spectra and angular distributions

    E-print Network

    Goetz, R Esteban; Santra, Robin; Koch, Christiane P

    2015-01-01

    Photoelectron spectra and photoelectron angular distributions obtained in photoionization reveal important information on e.g. charge transfer or hole coherence in the parent ion. Here we show that optimal control of the underlying quantum dynamics can be used to enhance desired features in the photoelectron spectra and angular distributions. To this end, we combine Krotov's method for optimal control theory with the time-dependent configuration interaction singles formalism and a splitting approach to calculate photoelectron spectra and angular distributions. The optimization target can account for specific desired properties in the photoelectron angular distribution alone, in the photoelectron spectrum, or in both. We demonstrate the method for hydrogen and then apply it to argon under strong XUV radiation, maximizing the difference of emission into the upper and lower hemispheres, in order to realize directed electron emission in the XUV regime.

  4. TDS spectra analysis

    NASA Astrophysics Data System (ADS)

    Tomková, E.

    1996-05-01

    Methods of TDS spectra analysis start usually from the Polanyi-Wigner desorption rate equation. The Redhead approximative solution of the equation can be rearranged into a reduced form in which it serves as an analytical expression for the desorption rate versus time or temperature. Fitting the analytical form to an experimental curve we can confirm or deny the invariability of kinetic parameters — a desorption energy Ed and a preexponential factor ?l — and determine their values. If the parameters depend on surface coverage ? the application of the reduced form allows us to determine their values at ??0 and ?? ?0 and estimate the dependence Ed( ?), ?(?) from a single TDS spectrum. The method proposed in this paper is valid for the first-order kinetics of desorption; for the estimation mentioned above an assumption is made that desorption sites are identical and that E d as well as ?l changes with ? monotonously.

  5. Modeling Supernova Spectra

    NASA Astrophysics Data System (ADS)

    Hillier, D. John; Dessart, Luc; Li, Chendong

    2012-04-01

    We highlight results from a series of investigations into modeling spectra of core-collapse supernovae (SNe). We have explored the accuracy of the expanding-photosphere method, and found that it can be used to obtain distances to Type IIP SNe with an accuracy of <~10%. We confirm the result of Utrobin and Chugai (2005) that time-dependent terms must be included in the statistical equilibrium equations in order to model Hi line evolution in Type II SNe, and show that time-dependent terms influence other spectral features (e.g., He i lines). We have initiated a study of polarization signatures from aspherical but axially-symmetric Type II SN ejecta. Hillier and Li acknowledge support from STScI theory grant HST-AR-11756.01.A and NASA theory grant NNX10AC80G. Dessart acknowledges financial support from grant PIRG04-GA-2008-239184.

  6. Dust Spectra from Above and Below

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Spectra of martian dust taken by the Mars Exploration Rover Spirit's mini-thermal emission spectrometer are compared to that of the orbital Mars Global Surveyor's thermal emission spectrometer. The graph shows that the two instruments are in excellent agreement.

    Rover Senses Carbon Dioxide [figure removed for brevity, see original site] Click on image for larger view

    This graph, consisting of data acquired on Mars from the Mars Exploration Rover Spirit's mini-thermal emission spectrometer, shows the light, or spectral, signature of carbon dioxide. Carbon dioxide makes up the bulk of the thin martian atmosphere.

    Rover Senses Silicates [figure removed for brevity, see original site] Click on image for larger view

    This graph, consisting of data acquired on Mars by the Mars Exploration Rover Spirit's mini-thermal emission spectrometer, shows the light, or spectral, signature of silicates - a group of minerals that form the majority of Earth's crust. Minerals called feldspars and zeolites are likely candidates responsible for this feature.

    Rover Senses Bound Water [figure removed for brevity, see original site] Click on image for larger view

    This graph, consisting of data acquired on Mars from the Mars Exploration Rover Spirit's mini-thermal emission spectrometer, shows the light, or spectral, signature of an as-of-yet unidentified mineral that contains bound water in its crystal structure. Minerals such as gypsum and zeolites are possible candidates.

    Rover Senses Carbonates [figure removed for brevity, see original site] Click on image for larger view

    This graph, consisting of data from the Mars Exploration Rover Spirit's mini-thermal emission spectrometer, shows the light, or spectral, signatures of carbonates - minerals common to Earth that form only in water. The detection of trace amounts of carbonates on Mars may be due to an interaction between the water vapor in the atmosphere and minerals on the surface.

  7. Investigating the Near-Infrared Properties of Planetary Nebulae II. Medium Resolution Spectra. 2; Medium Resolution Spectra

    NASA Technical Reports Server (NTRS)

    Hora, Joseph L.; Latter, William B.; Deutsch, Lynne K.

    1998-01-01

    We present medium-resolution (R approximately 700) near-infrared (lambda = 1 - 2.5 micrometers) spectra of a sample of planetary nebulae (PNe). A narrow slit was used which sampled discrete locations within the nebulae; observations were obtained at one or more positions in the 41 objects included in the survey. The PN spectra fall into one of four general categories: H1 emission line-dominated PNe, H1 and H2 emission line PNe, H2 emission line-dominated PNe, and continuum-dominated PNe. These categories correlate with morphological type, with the elliptical PNe falling into the first group, and the bipolar PNe primarily in the H2 and continuum emission groups. The categories also correlate with C/O ratio, with the O-rich objects falling into the first group and the C-rich objects in the groups. Other spectral features were observed in all catagories, such as continuum emission from the central star, and warm dust continuum emission towards the long wavelength end of the spectra. H2 was detected in four PNe in this survey for the first time. An analysis was performed using the H2 line ratios in all of the PN spectra in the survey where a sufficient number of lines were observed to determine the ortho-to-para ratio and the rotational and vibrational excitation temperatures of the H-2 in those objects. One unexpected result from this analysis is that the H-2 is excited by absorption of ultraviolet photons in most of the PNe, although there are several PNe in which collisional excitation plays an important role. The correlation between bipolar morphology and H2 emission has been strengthened with the new detections of H2 in this survey.

  8. 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...

  9. CLASSIFICATION OF STELLAR SPECTRA WITH LOCAL LINEAR EMBEDDING

    SciTech Connect

    Daniel, Scott F.; Connolly, Andrew; Vanderplas, Jake; Schneider, Jeff; Xiong Liang

    2011-12-15

    We investigate the use of dimensionality reduction techniques for the classification of stellar spectra selected from the Sloan Digital Sky Survey. Using local linear embedding (LLE), a technique that preserves the local (and possibly nonlinear) structure within high-dimensional data sets, we show that the majority of stellar spectra can be represented as a one-dimensional sequence within a three-dimensional space. The position along this sequence is highly correlated with spectral temperature. Deviations from this 'stellar locus' are indicative of spectra with strong emission lines (including misclassified galaxies) or broad absorption lines (e.g., carbon stars). Based on this analysis, we propose a hierarchical classification scheme using LLE that progressively identifies and classifies stellar spectra in a manner that requires no feature extraction and that can reproduce the classic MK classifications to an accuracy of one type.

  10. Effects of Forsterite Grain Shape on Infrared Spectra

    NASA Astrophysics Data System (ADS)

    Koike, C.; Imai, Y.; Chihara, H.; Suto, H.; Murata, K.; Tsuchiyama, A.; Tachibana, S.; Ohara, S.

    2010-02-01

    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 ?m. The spectra depend on particle shape. The spectra of the 11, 19, 23, and 33 ?m bands, in particular, are extremely sensitive to particle shape, whereas some peaks such as the 11.9, 49, and 69 ?m 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°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°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 ?m, may be due to spherical or spherical-like forsterite.

  11. EFFECTS OF FORSTERITE GRAIN SHAPE ON INFRARED SPECTRA

    SciTech Connect

    Koike, C.; Imai, Y.; Chihara, H.; Murata, K.; Tsuchiyama, A.; Suto, H.; Tachibana, S.; Ohara, S.

    2010-02-01

    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.

  12. Spectra of hot stars

    NASA Astrophysics Data System (ADS)

    Hillier, D. John

    2015-08-01

    Non-LTE modeling is essential for interpreting the spectra of O stars and their decendents, and much progress has been made. The major uncertainty associated with analyzing photospheric spectra of O stars arises from issues related to microturbulence and macroturbulence. Many supergiants, for example, have microturbulent velocities that approach the sound speed, while macroturbulent velocities are often several times the sound speed. The cause of this turbulence is unknown, but may be related to pulsation, an underlying convection zone associated with the Fe opacity bump, or feedback from the stellar wind. Determining accurate abundances in O stars is hampered by the lack of lines belonging to low-z elements. Many species only have a few observable lines, and some of these are subject to complex non-LTE effects. A characteristic of massive stars is the existence of a stellar wind which is driven by radiation pressure. Radiation driving is inherently unstable, and this leads to winds with an inhomogeneous structure. Major issues that are still unresolved include: How are winds driven through the sonic point? What is the nature of the inhomogeneities, and how do the properties of these inhomogeneities change with density and velocity? How important is spatial porosity, and porosity in velocity space? What is the structure of the shocks, and in what stars do the shocks fail to cool? With Wolf-Rayet (W-R) stars the major uncertainty arises because the classic spectroscopic radius (i.e., the location where ? = 2/3) often refers to a location in the wind — not necessarily the stellar radius associated with stellar evolution models. Derived radii are typically several times those predicted by stellar evolution calculations, although for strong-lined W-R stars it is possible to construct models that are consistent with evolution calculations. The driving of the winds in these stars is strongly coupled to the closeness of the stars to the Eddington limit and to their inhomogeneities, and the latter have not been derived from first principles. Theoretically, it is possible that the radii of the stars are inflated due to the Fe opacity bump.

  13. Twenty southern peculiar emission-line stars

    NASA Technical Reports Server (NTRS)

    Carlson, E. D.; Henize, K. G.

    1979-01-01

    Observational data for 20 southern stars having emission-line spectra that suggest a significant degree of mass ejection are given in order to present an atlas of their spectra and to give a quantitative description of their appearance during the 1961-62 epoch. Most of the stars are P Cygni stars; others include nova-like, peculiar Be, and symbiotic stars, as well as stellar planetary nebulae and emission-line binaries, all of whose spectra were obtained with the Newtonian two-prism Zeiss Spectrograph and the 74-inch reflector at Mount Stromlo Observatory. It is noted that among the P Cygni stars, there is a strong correlation between the a-e expansion velocity and the strength of Balmer emission, while in both the P Cygni and the Bep stars, there is positive dependence of Fe II and negative dependence of (Fe II) emission strengths on Balmer emission strength.

  14. Dynamic energy/power spectra from X-ray spectra and light curves

    NASA Astrophysics Data System (ADS)

    Ness, Jan-Uwe

    2015-09-01

    The key data product of an X-ray observation is an events table with information of calibrated position, energy, and arrival time for each individual X-ray photon. Many X-ray sources are variable and clues for origins for variations can be found in spectral changes along with light curve variations. This is commonly done by extracting spectra from certain episodes of variability such as low-states/high-states. I present a systematic approach of a dynamic X-ray spectrum, a 3-dimensional representation of wavelength/energy, time, and intensity. It is constructed from a series of spectra extracted from adjacent short time intervals, displayed as wavelength (or energy) versus time and a colour code for intensity. The same concept can be used for dynamic power spectra, displaying the evolution of periodic oscillations in an X-ray light curve. Dynamic energy/power spectra constructed from XMM-Newton and Chandra data have revealed some surprises such as short-lived emission lines during a flare, softening owed to changes in the absorption column of OI, or transient short-period oscillations in various supersoft sources. Some examples are shown to illustrate the diagnostic power of these diagrams.

  15. Interpreting Chromosome Aberration Spectra

    NASA Technical Reports Server (NTRS)

    Levy, Dan; Reeder, Christopher; Loucas, Bradford; Hlatky, Lynn; Chen, Allen; Cornforth, Michael; Sachs, Rainer

    2007-01-01

    Ionizing radiation can damage cells by breaking both strands of DNA in multiple locations, essentially cutting chromosomes into pieces. The cell has enzymatic mechanisms to repair such breaks; however, these mechanisms are imperfect and, in an exchange process, may produce a large-scale rearrangement of the genome, called a chromosome aberration. Chromosome aberrations are important in killing cells, during carcinogenesis, in characterizing repair/misrepair pathways, in retrospective radiation biodosimetry, and in a number of other ways. DNA staining techniques such as mFISH ( multicolor fluorescent in situ hybridization) provide a means for analyzing aberration spectra by examining observed final patterns. Unfortunately, an mFISH observed final pattern often does not uniquely determine the underlying exchange process. Further, resolution limitations in the painting protocol sometimes lead to apparently incomplete final patterns. We here describe an algorithm for systematically finding exchange processes consistent with any observed final pattern. This algorithm uses aberration multigraphs, a mathematical formalism that links the various aspects of aberration formation. By applying a measure to the space of consistent multigraphs, we will show how to generate model-specific distributions of aberration processes from mFISH experimental data. The approach is implemented by software freely available over the internet. As a sample application, we apply these algorithms to an aberration data set, obtaining a distribution of exchange cycle sizes, which serves to measure aberration complexity. Estimating complexity, in turn, helps indicate how damaging the aberrations are and may facilitate identification of radiation type in retrospective biodosimetry.

  16. Nebular spectra of pair-instability supernovae

    NASA Astrophysics Data System (ADS)

    Jerkstrand, A.; Smartt, S. J.; Heger, A.

    2016-01-01

    If very massive stars (M ? 100 M?) can form and avoid too strong mass-loss during their evolution, they are predicted to explode as pair-instability supernovae (PISNe). One critical test for candidate events is whether their nucleosynthesis yields and internal ejecta structure, being revealed through nebular-phase spectra at t ? 1 yr, match those of model predictions. Here, we compute theoretical spectra based on model PISN ejecta at 1-3 yr post-explosion to allow quantitative comparison with observations. The high column densities of PISNe lead to complete gamma-ray trapping for t ? 2 yr which, combined with fulfilled conditions of steady state, leads to bolometric supernova luminosities matching the 56Co decay. Most of the gamma-rays are absorbed by the deep-lying iron and silicon/sulphur layers. The ionization balance shows a predominantly neutral gas state, which leads to emission lines of Fe I, Si I, and S I. For low-mass PISNe, the metal core expands slowly enough to produce a forest of distinct lines, whereas high-mass PISNe expand faster and produce more featureless spectra. Line blocking is complete below ˜5000 Å for several years, and the model spectra are red. The strongest line is typically [Ca II] ??7291, 7323, one of few lines from ionized species. We compare our models with proposed PISN candidates SN 2007bi and PTF12dam, finding discrepancies for several key observables and thus no support for a PISN interpretation. We discuss distinct spectral features predicted by the models, and the possibility of detecting pair-instability explosions among non-superluminous supernovae.

  17. Polarization effects in cutaneous autofluorescent spectra

    NASA Astrophysics Data System (ADS)

    Borisova, E.; Angelova, L.; Jeliazkova, Al.; Genova, Ts.; Pavlova, E.; Troyanova, P.; Avramov, L.

    2014-05-01

    Used polarized light for fluorescence excitation one could obtain response related to the anisotropy features of extracellular matrix. The fluorophore anisotropy is attenuated during lesions' growth and level of such decrease could be correlated with the stage of tumor development. Our preliminary investigations are based on in vivo point-by-point measurements of excitation-emission matrices (EEM) from healthy volunteers skin on different ages and from different anatomical places using linear polarizer and analyzer for excitation and emission light detected. Measurements were made using spectrofluorimeter FluoroLog 3 (HORIBA Jobin Yvon, France) with fiber-optic probe in steady-state regime using excitation in the region of 280-440 nm. Three different situations were evaluated and corresponding excitation-emission matrices were developed - with parallel and perpendicular positions for linear polarizer and analyzer, and without polarization of excitation and fluorescence light detected from a forearm skin surface. The fluorescence spectra obtained reveal differences in spectral intensity, related to general attenuation, due to filtering effects of used polarizer/analyzer couple. Significant spectral shape changes were observed for the complex autofluorescence signal detected, which correlated with collagen and protein cross-links fluorescence, that could be addressed to the tissue extracellular matrix and general condition of the skin investigated, due to morphological destruction during lesions' growth. A correlation between volunteers' age and the fluorescence spectra detected was observed during our measurements. Our next step is to increase developed initial database and to evaluate all sources of intrinsic fluorescent polarization effects and found if they are significantly altered from normal skin to cancerous state of the tissue, this way to develop a non-invasive diagnostic tool for dermatological practice.

  18. Projecting Spectra for Classroom Investigations.

    ERIC Educational Resources Information Center

    Sadler, Philip

    1991-01-01

    Describes an inexpensive spectrum projector that makes high-dispersion, high-efficiency diffraction gratings using a holographic process. Discusses classroom applications such as transmission spectra, absorption spectra, reflection characteristics of materials, color mixing, florescence and phosphorescence, and break up spectral colors. (MDH)

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

    SciTech Connect

    Gatuzz, E.; Mendoza, C.; Garcia, J.; Lohfink, A.; Kallman, T. R.; Witthoeft, M.; Bautista, M. A.; Palmeri, P.; Quinet, P. E-mail: claudio@ivic.gob.ve E-mail: alohfink@astro.umd.edu E-mail: michael.c.witthoeft@nasa.gov E-mail: palmeri@umons.ac.be

    2013-05-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

  2. Diagram spaces, diagram spectra, and spectra of units

    E-print Network

    Lind, John

    2009-01-01

    We compare the infinite loop spaces associated to symmetric spectra, orthogonal spectra, and EKMM S-modules. Each of these categories of structured spectra has a corresponding category of structured spaces that receives the infinite loop space functor \\Omega^\\infty. We prove that these models for spaces are Quillen equivalent and that the infinite loop space functors \\Omega^\\infty agree. This comparison is then used to show that two different constructions of the spectrum of units gl_1 R of a structured ring spectrum R agree.

  3. Intracavity absorption and emission spectroscopy of atoms in pulsed gas discharges

    SciTech Connect

    Serdyukov, V. I.; Poplavskii, Yu. A.; Sinitsa, L. N.

    2009-07-15

    Absorption and emission spectra of U and Na atoms in the 590-nm spectral range were studied experimentally using pulsed hollow-cathode gas discharges. The spectra were recorded with a high-sensitivity intracavity laser spectrometer. The possibility of generating coherent emission on atomic emission lines in gas-discharge plasmas was demonstrated experimentally.

  4. Features in the spectra of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Stanek, Krzysztof Z.; Paczynski, Bohdan; Goodman, Jeremy

    1993-01-01

    Gravitational lensing of cosmological gamma-ray bursts by objects in the mass range about 10 exp 17 to 10 exp 20 g (femtolensing) may introduce complicated interference patterns that might be interpreted as absorption or emission lines in the bursts' spectra. This phenomenon, if detected, may be used as a unique probe of dark matter in the universe. The BATSE spectral data should allow one to detect such spectral features or to put significant upper limits on the cosmic density of a dark matter component that may be in the femtolensing range. Software to generate theoretical spectra has been developed, and it is accessible over the computer network with anonymous ftp.

  5. RELATIONSHIP BETWEEN THE ABSORPTION AND EMISSION SPECTRA AND

    E-print Network

    Govindjee

    (see equation 3 in text) to suspensions of Chlorella, Porphyridium, and Anacystis and to chlorophyll in Porphyridium may begin at about 1.53 X 104cm' (654 m,u); in Anacystis, it may begin already above 1.57 X 104cm

  6. Emission reduction

    NASA Technical Reports Server (NTRS)

    Petrash, D. A.; Diehl, L. A.; Jones, R. E.; Mularz, E. J.

    1979-01-01

    Control of the gaseous pollutant emissions of aircraft engines is considered in terms of the emission standards for six classes of aircraft engines. Emphasis is placed on combustor design concepts to significantly reduce emissions levels and lean-burning techniques to lower flame temperature, to reduce the oxides of nitrogen in the gaseous emissions.

  7. IntrAst2 (Petrovay) Spectra STELLAR SPECTRA

    E-print Network

    Petrovay, Kristóf

    , Fleming): Classes A, B, ... etc. by decreasing importance of Balmer lines. 1901: Annie J. Cannon arranges: infrared domain #12;IntrAst2 (Petrovay) Spectra The Balmer series: H: Balmer jump At shorter values

  8. Middle ultraviolet emission from ionized iron

    NASA Astrophysics Data System (ADS)

    Dymond, K. F.; Wolfram, K. D.; Budzien, S. A.; Nicholas, A. C.; McCoy, R. P.; Thomas, R. J.

    2003-01-01

    We present middle ultraviolet spectra between 2300 and 2700 Å showing emissions due to singly ionized iron and magnesium. The spectra were observed by the Ionospheric Spectroscopy and Atmospheric Chemistry (ISAAC) instrument on the United States Air Force's Advanced Research and Global Observing Satellite (ARGOS). The emission from ionized magnesium has been previously observed and studied; however, the ionized iron lines near 2400 and 2600 Å are newly identified in the Earth's middle ultraviolet dayglow spectrum. Newly calculated fluorescence efficiencies for excitation of the optical emissions are also presented.

  9. Cluster analysis on mass spectra of biogenic secondary organic aerosol

    NASA Astrophysics Data System (ADS)

    Spindler, C.; Kiendler-Scharr, A.; Kleist, E.; Mensah, A.; Mentel, T.; Tillmann, R.; Wildt, J.

    2009-04-01

    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 (Jülich 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.

  10. Effect of insulator sleeve material on the x-ray emission from a plasma focus device

    SciTech Connect

    Hussain, S.; Badar, M. A.; Shafiq, M.; Zakaullah, M.

    2010-09-15

    The effect of insulator sleeve material on x-ray emission from a 2.3 kJ Mather type plasma focus device operated in argon-hydrogen mixture is investigated. The time and space resolved x-ray emission characteristics are studied by using a three channel p-i-n diode x-ray spectrometer and a multipinhole camera. The x-ray emission depends on the volumetric ratio of argon-hydrogen mixture as well as the filling pressure and the highest x-ray emission is observed for a volumetric ratio 40% Ar to 60%H{sub 2} at 2.5 mbar filling pressure. The fused silica insulator sleeve produces the highest x-ray emission whereas nonceramic insulator sleeves such as nylon, Perspex, or Teflon does not produce focus or x-rays. The pinhole images of the x-ray emitting zones reveal that the contribution of the Cu K{alpha} line is weak and plasma x-rays are intense. The highest plasma electron temperature is estimated to be 3.3 and 3.6 keV for Pyrex glass and fused silica insulator sleeves, respectively. It is speculated that the higher surface resistivity of fused silica is responsible for enhanced x-ray emission and plasma electron temperature.

  11. Scenario of temperature-related variation of phosphorescence spectra of ortho-bromobenzophenone crystal

    NASA Astrophysics Data System (ADS)

    Strzhemechny, M. A.; Stepanian, S. G.; Zloba, D. I.; Buravtseva, L. M.; Pyshkin, O. S.; Piryatinski, Yu. P.; Melnik, V. I.; Klishevich, G. V.; Adamowicz, L.

    2015-12-01

    Luminescence and other properties of solid 2-bromobenzophenone demonstrate features, which require special attention. We present results, which include DFT calculations, integrated and time-resolved phosphorescence spectra, and excitation spectra. The energies of the title molecule were calculated for the S0 , S1 , and T1 states. Nanosecond time-resolved phosphorescence spectra were measured at three temperature points at which the spectra undergo substantial changes. Joint analysis of energy surfaces and experimental evidence allowed reconstruction of the emission scenario that determines temperature-related variations of spectra. Upon excitation to state S1 the molecule converges very fast to T1 , emission from which can occur from the minima at 60° or at 180°. At low temperatures the molecule emits from the former, whereas at higher temperatures the molecule can overcome the barrier to emit from the lower minimum. The probability of excimer formation increases with increasing temperature.

  12. Radioactive sample effects on EDXRF spectra

    SciTech Connect

    Worley, Christopher G

    2008-01-01

    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.

  13. Infrared spectra of joint fluids

    NASA Astrophysics Data System (ADS)

    Eysel, Hans H.; Mantsch, Henry H.; Jackson, Michael

    1994-01-01

    The present study demonstrates the application of infrared spectroscopy to the diagnosis of arthritic conditions by analysis of joint fluids. The detection of carbon dioxide clathrates, their origin and the nature of the host material is discussed. The analytical sensitivity of mid IR second derivative spectra is demonstrated with the detection of the local anaesthetic lidocaine in some of the samples. Linear discriminant analysis and hierarchical clustering are successfully used to classify the spectra according to their respective clinical diagnosis.

  14. THEORETICAL SPECTRA OF TERRESTRIAL EXOPLANET SURFACES

    SciTech Connect

    Hu Renyu; Seager, Sara; Ehlmann, Bethany L.

    2012-06-10

    We investigate spectra of airless rocky exoplanets with a theoretical framework that self-consistently treats reflection and thermal emission. We find that a silicate surface on an exoplanet is spectroscopically detectable via prominent Si-O features in the thermal emission bands of 7-13 {mu}m and 15-25 {mu}m. The variation of brightness temperature due to the silicate features can be up to 20 K for an airless Earth analog, and the silicate features are wide enough to be distinguished from atmospheric features with relatively high resolution spectra. The surface characterization thus provides a method to unambiguously identify a rocky exoplanet. Furthermore, identification of specific rocky surface types is possible with the planet's reflectance spectrum in near-infrared broad bands. A key parameter to observe is the difference between K-band and J-band geometric albedos (A{sub g}(K) - A{sub g}(J)): A{sub g}(K) - A{sub g}(J) > 0.2 indicates that more than half of the planet's surface has abundant mafic minerals, such as olivine and pyroxene, in other words primary crust from a magma ocean or high-temperature lavas; A{sub g}(K) - A{sub g}(J) < -0.09 indicates that more than half of the planet's surface is covered or partially covered by water ice or hydrated silicates, implying extant or past water on its surface. Also, surface water ice can be specifically distinguished by an H-band geometric albedo lower than the J-band geometric albedo. The surface features can be distinguished from possible atmospheric features with molecule identification of atmospheric species by transmission spectroscopy. We therefore propose that mid-infrared spectroscopy of exoplanets may detect rocky surfaces, and near-infrared spectrophotometry may identify ultramafic surfaces, hydrated surfaces, and water ice.

  15. HF Accelerated Electron Fluxes, Spectra, and Ionization

    NASA Astrophysics Data System (ADS)

    Carlson, Herbert C.; Jensen, Joseph B.

    2015-10-01

    Wave particle interactions, an essential aspect of laboratory, terrestrial, and astrophysical plasmas, have been studied for decades by transmitting high power HF radio waves into Earth's weakly ionized space plasma, to use it as a laboratory without walls. Application to HF electron acceleration remains an active area of research (Gurevich in Usp Fizicheskikh Nauk 177(11):1145-1177, 2007) today. HF electron acceleration studies began when plasma line observations proved (Carlson et al. in J Atmos Terr Phys 44:1089-1100, 1982) that high power HF radio wave-excited processes accelerated electrons not to ~eV, but instead to -100 times thermal energy (10 s of eV), as a consequence of inelastic collision effects on electron transport. Gurevich et al (J Atmos Terr Phys 47:1057-1070, 1985) quantified the theory of this transport effect. Merging experiment with theory in plasma physics and aeronomy, enabled prediction (Carlson in Adv Space Res 13:1015-1024, 1993) of creating artificial ionospheres once ~GW HF effective radiated power could be achieved. Eventual confirmation of this prediction (Pedersen et al. in Geophys Res Lett 36:L18107, 2009; Pedersen et al. in Geophys Res Lett 37:L02106, 2010; Blagoveshchenskaya et al. in Ann Geophys 27:131-145, 2009) sparked renewed interest in optical inversion to estimate electron spectra in terrestrial (Hysell et al. in J Geophys Res Space Phys 119:2038-2045, 2014) and planetary (Simon et al. in Ann Geophys 29:187-195, 2011) atmospheres. Here we present our unpublished optical data, which combined with our modeling, lead to conclusions that should meaningfully improve future estimates of the spectrum of HF accelerated electron fluxes. Photometric imaging data can significantly improve detection of emissions near ionization threshold, and confirm depth of penetration of accelerated electrons many km below the excitation altitude. Comparing observed to modeled emission altitude shows future experiments need electron density profiles to derive more accurate HF electron flux spectra.

  16. Curved Radio Spectra of Weak Cluster Shocks

    NASA Astrophysics Data System (ADS)

    Kang, Hyesung; Ryu, Dongsu

    2015-08-01

    In order to understand certain observed features of arc-like giant radio relics such as the rareness, uniform surface brightness, and curved integrated spectra, we explore a diffusive shock acceleration (DSA) model for radio relics in which a spherical shock impinges on a magnetized cloud containing fossil relativistic electrons. Toward this end, we perform DSA simulations of spherical shocks with the parameters relevant for the Sausage radio relic in cluster CIZA J2242.8+5301, and calculate the ensuing radio synchrotron emission from re-accelerated electrons. Three types of fossil electron populations are considered: a delta-function like population with the shock injection momentum, a power-law distribution, and a power law with an exponential cutoff. The surface brightness profile of the radio-emitting postshock region and the volume-integrated radio spectrum are calculated and compared with observations. We find that the observed width of the Sausage relic can be explained reasonably well by shocks with speed {u}{{s}}˜ 3× {10}3 {km} {{{s}}}-1 and sonic Mach number {M}{{s}}˜ 3. These shocks produce curved radio spectra that steepen gradually over (0.1-10){? }{br} with a break frequency {? }{br}˜ 1 GHz if the duration of electron acceleration is ˜60-80 Myr. However, the abrupt increase in the spectral index above ˜1.5 GHz observed in the Sausage relic seems to indicate that additional physical processes, other than radiative losses, operate for electrons with {? }{{e}}? {10}4.

  17. Fourier transform spectra of quantum dots

    NASA Astrophysics Data System (ADS)

    Damian, V.; Ardelean, I.; Arm??elu, Anca; Apostol, D.

    2010-05-01

    Semiconductor quantum dots are nanometer-sized crystals with unique photochemical and photophysical properties that are not available from either isolated molecules or bulk solids. These nanocrystals absorb light over a very broad spectral range as compared to molecular fluorophores which have very narrow excitation spectra. High-quality QDs are proper to be use in different biological and medical applications (as fluorescent labels, the cancer treatment and the drug delivery). In this article, we discuss Fourier transform visible spectroscopy of commercial quantum dots. We reveal that QDs produced by Evident Technologies when are enlightened by laser or luminescent diode light provides a spectral shift of their fluorescence spectra correlated to exciting emission wavelengths, as shown by the ARCspectroNIR Fourier Transform Spectrometer. In the final part of this paper we show an important biological application of CdSe/ZnS core-shell ODs as microbial labeling both for pure cultures of cyanobacteria (Synechocystis PCC 6803) and for mixed cultures of phototrophic and heterotrophic microorganisms.

  18. Fourier transform spectra of quantum dots

    NASA Astrophysics Data System (ADS)

    Damian, V.; Ardelean, I.; Arm??elu, Anca; Apostol, D.

    2009-09-01

    Semiconductor quantum dots are nanometer-sized crystals with unique photochemical and photophysical properties that are not available from either isolated molecules or bulk solids. These nanocrystals absorb light over a very broad spectral range as compared to molecular fluorophores which have very narrow excitation spectra. High-quality QDs are proper to be use in different biological and medical applications (as fluorescent labels, the cancer treatment and the drug delivery). In this article, we discuss Fourier transform visible spectroscopy of commercial quantum dots. We reveal that QDs produced by Evident Technologies when are enlightened by laser or luminescent diode light provides a spectral shift of their fluorescence spectra correlated to exciting emission wavelengths, as shown by the ARCspectroNIR Fourier Transform Spectrometer. In the final part of this paper we show an important biological application of CdSe/ZnS core-shell ODs as microbial labeling both for pure cultures of cyanobacteria (Synechocystis PCC 6803) and for mixed cultures of phototrophic and heterotrophic microorganisms.

  19. Principal component analysis of IUE galaxy spectra

    E-print Network

    Liliana Formiggini; Noah Brosch

    2004-02-12

    We analyse the UV spectral energy distribution of a sample of normal galaxies listed in the IUE-INES Guide No. 2-Normal Galaxies (Formiggini & Brosch, 2000) using a Principal Component Analysis. The sample consists of the IUE-SW spectra of the central regions of 118 galaxies, where the IUE aperture included more than 1 per cent of the galaxy size. The principal components are associated with the main components observed in the UV spectra of galaxies. The first component, accounting for the largest source of diversity, can be associated with the UV continuum emission. The second component represents the UV contribution of an underlying evolved stellar population. The third component is sensitive to the amount of activity in the central regions of galaxies and measures the strength of star formation events. In all the samples analysed here the principal component representative of star-forming activity accounts for a significant percentage of the variance. The fractional contribution to the SED by the evolved stars and by the young population are similar. Projecting the SEDs onto their eigenspectra, we find that none of the coefficients of the principal components can outline an internal correlation or can correlate with the optical morphological types. In a sub-sample of 43 galaxies, consisting of almost only compact and BCD galaxies, the third principal component defines a sequence related to the degree of starburst activity of the galaxy.

  20. An atlas of selected calibrated stellar spectra

    NASA Technical Reports Server (NTRS)

    Walker, Russell G.; Cohen, Martin

    1992-01-01

    Five hundred and fifty six stars in the IRAS PSC-2 that are suitable for stellar radiometric standards and are brighter than 1 Jy at 25 microns were identified. In addition, 123 stars that meet all of our criteria for calibration standards, but which lack a luminosity class were identified. An approach to absolute stellar calibration of broadband infrared filters based upon new models of Vega and Sirius due to Kurucz (1992) is presented. A general technique used to assemble continuous wide-band calibrated infrared spectra is described and an absolutely calibrated 1-35 micron spectrum of alpha(Tau) is constructed and the method using new and carefully designed observations is independently validated. The absolute calibration of the IRAS Low Resolution Spectrometer (LRS) database is investigated by comparing the observed spectrum of alpha(Tau) with that assumed in the original LRS calibration scheme. Neglect of the SiO fundamental band in alpha(Tau) has led to the presence of a specious 'emission' feature in all LRS spectra near 8.5 microns, and to an incorrect spectral slope between 8 and 12 microns. Finally, some of the properties of asteroids that effect their utility as calibration objects for the middle and far infrared region are examined. A technique to determine, from IRAS multiwaveband observations, the basic physical parameters needed by various asteroid thermal models that minimize the number of assumptions required is developed.

  1. Spectra of thermally unstable slim discs

    E-print Network

    Ewa Szuszkiewicz; Roberto Turolla; Luca Zampieri

    2000-11-21

    Thermal instability driven by radiation pressure might be relevant for intrinsically bright accreting sources. The most promising candidate where this instability seems to be at work is one of the two known galactic superluminal sources, GRS 1915+105 (Belloni et al. 1997). In spite of being of relevance, this scenario has not yet been confirmed by proper time-dependent modelling. Non-linear time-dependent calculations performed by Szuszkiewicz and Miller (1998) show that thermally unstable discs undergo limit-cycle behaviour with successive evacuation and refilling of the central parts of the disc. This evolution is very similar to the one proposed by Belloni et al. (1997) in their phenomenological model. Further investigations are needed to confirm the thermal instability being operational in this source. First of all the spectra emitted from the disc during its evolution should be calculated and compared with observations. Here such spectra are computed assuming local blackbody emission from the best studied transonic disc model.

  2. Fluorescence spectra of the NaI molecule

    NASA Astrophysics Data System (ADS)

    Ragone, Anthony S.; Levy, Donald H.; Berry, R. Stephen

    1982-10-01

    The fluorescence excitation spectrum and fluorescence emission spectra of sodium iodide vapor are reported for the first time. The emission spectrum contains a v = 0 progression and v = 1 progression of a transition of the NaI molecule, as well as many other bands due to other species. The spectrum is taken from a seeded hypersonic nozzle beam excited by a tunable laser. A vibrational analysis is given, part of the upper state potential is constructed, and the results are related to photodissociation studies.

  3. Demonstrating Absorption Spectra Using Commercially Available Incandescent Light Bulbs

    NASA Astrophysics Data System (ADS)

    Birriel, Jennifer J.

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

  4. An atlas of ultraviolet spectra of star-forming galaxies

    NASA Technical Reports Server (NTRS)

    Kinney, A. L.; Bohlin, R. C.; Calzetti, D.; Panagia, N.; Wyse, Rosemary F. G.

    1993-01-01

    A systematic study is presented of the UV spectra of star-forming galaxies of different morphological type and activity class using a sample drawn from a uniformly reduced IUE data set. The spectra for a wide variety of galaxies, including normal spiral, LINER, starburst, blue compact, blue compact dwarf, and Seyfert 2 galaxies, are presented in the form of spectral energy distributions to demonstrate the overall characteristics according to morphology and activity class and in the form of absolute flux distributions to better show the absorption and emission features of individual objects. The data support the picture based on UV spectra of the Orbiting Astronomical Observatory and of the Astronautical Netherlands Satellite that spiral galaxies of later Hubble class have more flux at the shortest UV wavelengths than do spiral galaxies of earlier Hubble class.

  5. Charged lepton spectra from hot-spot evaporation

    E-print Network

    Julian Moosmann; Ralf Hofmann

    2009-08-11

    Spectra for the emission of charged leptons from evaporating hot-spots of preconfining phase in SU(2) Yang-Mills thermodynamics are computed. Specifically, we consider charged single and dileptons with their spectra being functions of energy and invariant mass, respectively. In the former case, our results relate to narrow and correlated electron and positron peaks measured in supercritical heavy-ion collisions performed at GSI in the 1980ies. In the latter case, we point out how strongly the spectra depend on typical kinematic cuts (CDF analysis of Tevatron Run II data). We also propose a scenario on how muon events of anomalously high multiplicity and large impact-parameter modulus arise in the Tevatron data.

  6. 5-14 ?m Spitzer spectra of Themis family asteroids

    NASA Astrophysics Data System (ADS)

    Licandro, J.; Hargrove, K.; Kelley, M.; Campins, H.; Ziffer, J.; Alí-Lagoa, V.; Fernández, Y.; Rivkin, A.

    2012-01-01

    Context. The Themis collisional family is one of the largest and best established families in the main belt. Composed of primitive asteroids, there is evidence that water is likely present in a large fraction of its members, either in aqueously altered silicates or in water ice reservoirs. The study of the abundance of water in the outer asteroid belt is important as it may be linked to the origin of Earth's water. Studying the Themis family can also help to constrain the compositional and thermal environment in the region of the solar nebula where these asteroids formed. Aims: Our aim is to constrain the composition and thermal properties of the surfaces of several Themis family asteroids. Methods: We present 5-14 ?m spectra of 8 Themis family asteroids observed with Spitzer: (222) Lucia, (223) Rosa, (316) Goberta, (383) Janina, (468) Lina, (492) Gismonda, (515) Athalia, and (526) Jena. We determine their diameters, geometric albedos and beaming parameters using the near-Earth asteroid thermal model. Their emissivity spectra are studied in order to determine if they exhibit an emission plateau from 9 to 12 ?m which has been observed in other primitive asteroids and attributed to fine-grained silicates (the Si-O stretch fundamental). Results: The derived mean albedo of our sample of Themis family asteroids is bar pV = 0.07 ± 0.02 = 0.07 ± 0.02, and the mean beaming parameter is bar ? = 1.05 ± 0.10. The derived bar ? value is close to unity, which implies that the infrared beaming is not significant, there is likely little night-side emission from the asteroids, and the thermal inertia is probably low. The emissivity spectra of at least 5 of our 8 asteroids show a 9-12 ?m emission plateau with spectral contrast of 2-4%, similar but smaller than that observed in the spectra of Trojan asteroids and cometary dust. The plateau may be due to the surfaces having either small silicate grains embedded in a relatively transparent matrix, or from a very under-dense (fairy-castle) surface structure. Conclusions: The surfaces of a large fraction of Themis family asteroids with D 50 km are covered by a fine grained silicate mantle as observed on Trojan asteroids of similar or larger size. The lower amplitude of the silicate emission in Themis family asteroids spectra (2-4%) with respect to that of Trojan asteroids (10-15%) could be attributed to larger dust particles, a slightly denser structure, or a lower silicate dust fraction.

  7. Analysis of photometric spectra of 17 meteors

    NASA Technical Reports Server (NTRS)

    Millman, P. M.

    1982-01-01

    The initial phase of the photometry which involved 17 meteor spectra consisting of eight Geminid spectra, six Orionid spectra and three Eta Aquarid spectra is discussed. Among these 17 spectra it is found that the Geminid spectra are of the best quality and are used for the identification of the atomic lines and molecular bands that normally appear on video tape spectra. The data from the Geminid records are used for developing calibration techniques in photometry. The Orionid and Eta Aquarid spectra are chosen for early analysis because of the current interest in all physical and chemical data relating to Comet Halley.

  8. Visible emission of hydrogen flames

    SciTech Connect

    Schefer, R.W.; Kulatilaka, W.D.; Patterson, B.D.; Settersten, T.B.

    2009-06-15

    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)

  9. Supernova spectra below strong circumstellar interaction

    NASA Astrophysics Data System (ADS)

    Leloudas, G.; Hsiao, E. Y.; Johansson, J.; Maeda, K.; Moriya, T. J.; Nordin, J.; Petrushevska, T.; Silverman, J. M.; Sollerman, J.; Stritzinger, M. D.; Taddia, F.; Xu, D.

    2015-02-01

    We construct spectra of supernovae (SNe) interacting strongly with a circumstellar medium (CSM) by adding SN templates, a black-body continuum, and an emission-line spectrum. In a Monte Carlo simulation we vary a large number of parameters, such as the SN type, brightness and phase, the strength of the CSM interaction, the extinction, and the signal to noise ratio (S/N) of the observed spectrum. We generate more than 800 spectra, distribute them to ten different human classifiers, and study how the different simulation parameters affect the appearance of the spectra and their classification. The SNe IIn showing some structure over the continuum were characterized as "SNe IInS" to allow for a better quantification. We demonstrate that the flux ratio of the underlying SN to the continuum fV is the single most important parameter determining whether a spectrum can be classified correctly. Other parameters, such as extinction, S/N, and the width and strength of the emission lines, do not play a significant role. Thermonuclear SNe get progressively classified as Ia-CSM, IInS, and IIn as fV decreases. The transition between Ia-CSM and IInS occurs at fV ~ 0.2-0.3. It is therefore possible to determine that SNe Ia-CSM are found at the (un-extincted) magnitude range -19.5 >M> -21.6, in very good agreement with observations, and that the faintest SN IIn that can hide a SN Ia has M = -20.1. The literature sample of SNe Ia-CSM shows an association with 91T-like SNe Ia. Our experiment does not support that this association can be attributed to a luminosity bias (91T-like being brighter than normal events). We therefore conclude that this association has real physical origins and we propose that 91T-like explosions result from single degenerate progenitors that are responsible for the CSM. Despite the spectroscopic similarities between SNe Ibc and SNe Ia, the number of misclassifications between these types was very small in our simulation and mostly at low S/N. Combined with the SN luminosity function needed to reproduce the observed SN Ia-CSM luminosities, it is unlikely that SNe Ibc constitute an important contaminant within this sample. We show how Type II spectra transition to IIn and how the H? profiles vary with fV. SNe IIn fainter than M = -17.2 are unable to mask SNe IIP brighter than M = -15. A more advanced simulation, including radiative transfer, shows that our simplified model is a good first order approximation. The spectra obtained are in good agreement with real data.

  10. Photon spectra from WIMP annihilation

    SciTech Connect

    Cembranos, J. A. R.; Cruz-Dombriz, A. de la; Dobado, A.; Maroto, A. L.; Lineros, R. A.

    2011-04-15

    If the present dark matter in the Universe annihilates into standard model particles, it must contribute to the fluxes of cosmic rays that are detected on the Earth and, in particular, to the observed gamma-ray fluxes. The magnitude of such a contribution depends on the particular dark matter candidate, but certain features of the produced photon spectra may be analyzed in a rather model-independent fashion. In this work we provide the complete photon spectra coming from WIMP annihilation into standard model particle-antiparticle pairs obtained by extensive Monte Carlo simulations. We present results for each individual annihilation channel and provide analytical fitting formulas for the different spectra for a wide range of WIMP masses.

  11. QUALITATIVE INTERPRETATION OF GALAXY SPECTRA

    SciTech Connect

    Sanchez Almeida, J.; Morales-Luis, A. B.; Terlevich, R.; Terlevich, E.; Cid Fernandes, R. E-mail: abml@iac.es E-mail: eterlevi@inaoep.mx

    2012-09-10

    We describe a simple step-by-step guide to qualitative interpretation of galaxy spectra. Rather than an alternative to existing automated tools, it is put forward as an instrument for quick-look analysis and for gaining physical insight when interpreting the outputs provided by automated tools. Though the recipe is for general application, it was developed for understanding the nature of the Automatic Spectroscopic K-means-based (ASK) template spectra. They resulted from the classification of all the galaxy spectra in the Sloan Digital Sky Survey data release 7, thus being a comprehensive representation of the galaxy spectra in the local universe. Using the recipe, we give a description of the properties of the gas and the stars that characterize the ASK classes, from those corresponding to passively evolving galaxies, to H II galaxies undergoing a galaxy-wide starburst. The qualitative analysis is found to be in excellent agreement with quantitative analyses of the same spectra. We compare the mean ages of the stellar populations with those inferred using the code STARLIGHT. We also examine the estimated gas-phase metallicity with the metallicities obtained using electron-temperature-based methods. A number of byproducts follow from the analysis. There is a tight correlation between the age of the stellar population and the metallicity of the gas, which is stronger than the correlations between galaxy mass and stellar age, and galaxy mass and gas metallicity. The galaxy spectra are known to follow a one-dimensional sequence, and we identify the luminosity-weighted mean stellar age as the affine parameter that describes the sequence. All ASK classes happen to have a significant fraction of old stars, although spectrum-wise they are outshined by the youngest populations. Old stars are metal-rich or metal-poor depending on whether they reside in passive galaxies or in star-forming galaxies.

  12. Principal component and sensitivity analysis of cirrus clouds using high-resolution IR radiance spectra: simulations and observations

    NASA Technical Reports Server (NTRS)

    Eldering, A.; Braverman, A.; Fetzer, E. J.

    2003-01-01

    A set of simulated and observed nadir-oriented high-resolution infrared emission spectra of synthetic cirrus clouds is analyzed to assess the spectrally dependent variability of radiance from the adjustment of some microphysical and bulk cirrus cloud properties.

  13. Classical Trajectories and Quantum Spectra

    NASA Technical Reports Server (NTRS)

    Mielnik, Bogdan; Reyes, Marco A.

    1996-01-01

    A classical model of the Schrodinger's wave packet is considered. The problem of finding the energy levels corresponds to a classical manipulation game. It leads to an approximate but non-perturbative method of finding the eigenvalues, exploring the bifurcations of classical trajectories. The role of squeezing turns out decisive in the generation of the discrete spectra.

  14. The LickX spectra

    NASA Astrophysics Data System (ADS)

    Worthey, G.; Danilet, A. B.; Faber, S. M.

    2014-01-01

    Context. Collections of stellar spectra, often called stellar libraries, are useful in a variety of applications in the field of stellar populations. Aims: This is an attempt to improve the much-used Lick library of stellar spectra by removing jitter from the wavelength scale via cross-correlation, and calling the result the LickX library. Methods: Each spectrum was cross-correlated with a template spectrum and a new wavelength solution sought. Low-order polynomials were fit to adjust the old scale to a new fit. Indices were measured, new standard star averages found, and adjusted averages derived for the program stars. Results: The greatest gains in accuracy are expected for the fainter stars and stars of extreme surface temperatures; the bright K giant standard stars in LickX have the same uncertainties as Lick. The spectra and a table of index measurements in which repeated measurements are averaged are made available electronically. Individual stellar spectra, in FITS files, and the ascii catalog of absorption feature index strengths are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/561/A36

  15. Isochoric heating of reduced mass targets by ultra-intense laser produced relativistic electrons

    SciTech Connect

    Neumayer, P; Lee, H J; Offerman, D; Shipton, E; Kemp, A; Kritcher, A L; Doppner, T; Back, C A; Glenzer, S H

    2009-02-04

    We present measurements of the chlorine K-alpha emission from reduced mass targets, irradiated with ultra-high intensity laser pulses. Chlorinated plastic targets with diameters down to 50 micrometers and mass of a few 10{sup -8} g were irradiated with up to 7 J of laser energy focused to intensities of several 10{sup 19} W/cm{sup 2}. The conversion of laser energy to K-alpha radiation is measured, as well as high resolution spectra that allow observation of line shifts, indicating isochoric heating of the target up to 18 eV. A zero-dimensional 2-temperature equilibration model, combined with electron impact K-shell ionization and post processed spectra from collisional radiative calculations reproduces the observed K-alpha yields and line shifts, and shows the importance of target expansion due to the hot electron pressure.

  16. Magnetic emissions of electric appliances.

    PubMed

    Leitgeb, N; Cech, R; Schröttner, J; Lehofer, P; Schmidpeter, U; Rampetsreiter, M

    2008-03-01

    More than 1000 electric appliances have been investigated regarding their emission of magnetic fields. It was found that complex frequency spectra are common and single frequency emissions are rare. Since exposure assessment requires frequency-weighted sums, root-mean-square values are not appropriate for comparison with exposure reference levels. It could be shown that they may underestimate emissions up to two orders of magnitude. Analysis of device groups showed a wide span of emission values of up to two orders of magnitude with only weak associations to power consumption. This demonstrates that there is a considerable potential to reduce fields without loss of performance. Exposure to magnetic fields of electric appliances are not negligible in daily life. Many devices considerably exceeded permitted reference levels and would require a closer analysis to demonstrate conformity with basic limits. PMID:17611151

  17. Thermal Infrared Spectra of Comet HaleBopp at Heliocentric Distances of 4 and 2.9 AU.

    E-print Network

    Davies, John Keith

    Thermal Infrared Spectra of Comet Hale­Bopp at Heliocentric Distances of 4 and 2.9 AU. John K. We present 10 and 20¯m spectra of Comet Hale­Bopp taken at UKIRT on 1996 June 20 and 1996 September words: comet, infrared, dust, silicates 1. Introduction Emission features in the 10¯m region have been

  18. Cloud Processing of CCN Spectra

    NASA Astrophysics Data System (ADS)

    Hudson, J. G.; Noble, S. R., Jr.

    2014-12-01

    Cloud processing often makes bimodal aerosol spectra from which size at minimal concentration infers cloud effective supersaturation (Seff) (Hoppel et al. 1986). Particle hygroscopicity (?) converts this Hoppel minimum to critical S, Sc. Only lower Sc particles that produce cloud droplets are physically (coalescence) or chemically (gas-to-particle conversion) processed, which increases soluble content so that upon evaporation, these CCN have even lower Sc whereas the unactivated CCN do not change size or Sc. This results in the size gap at Seff. DRI CCN spectrometers have revealed bimodality in 6 projects for which Seff can be obtained without ?. However in 2 projects, MASE and ICE-T, simultaneous DMA measurements also provided ? by transposing DMA sizes to Sc; the ? that makes the DMA spectra agree with simultaneous CCN spectra (Fig). There was DMA-CCN agreement for 227 MASE and 50 ICE-T measurements. Since unlike Fig. a mean ? of the processed modes was greater than mean ? of the unprocessed modes, chemical processing was indicated; since most ? were lower than ammonium sulfate ? (0.61) chemical processing should move processed ? closer to 0.61. Chemical processing was also indicated in MASE by greater sulfate and nitrate concentrations for bimodal spectra and greater sulfur dioxide and ozone concentrations for monomodal spectra. MASE above cloud measurements showed higher ? and less bimodality than below cloud measurements, this is consistent with the higher above cloud NCCN, that ? is lower in pollution and for these less cloud interacted samples. Interspersed bimodal and monomodal CCN spectra under the ubiquitous MASE stratus suggested less than well-mixed boundary layers. Somewhat surprisingly there was more bimodality for the cumulus ICE-T clouds than the MASE stratus. ICE-T indicated more physical than chemical cloud processing. Cloud-processing of CCN spectra is as important as CCN sources; it alters Seff, cloud droplet concentrations, mean diameter, spectral width and albedo. These changes and the lower Hoppel minima Seff than Seff from spectral comparisons with droplet concentrations; i.e., probably due to unprocessed small droplets, could be additional or counter indirect aerosol effects.

  19. Features of the NCth in SEE spectra

    NASA Astrophysics Data System (ADS)

    Frolov, V. L.; Nedzvetski, D. I.; Sergeev, E. N.

    Basing on experiments carried out at the Sura heating facility it has been elaborated an empirical model for generation of the thermal narrow continuum NC th in stimulated electromagnetic emission SEE spectra which is observed in the lower sideband of the pump wave PW frequency extending up to the down-shifted maximum DM and the spectral intensity of which decreases exponentially with the increase of frequency shift from the pump The generation of NC th as well as DM and broad continuum BC occurs due to excitation of the thermal resonance parametric instability TPI Integral intensity of the NC th is close to or even higher than DM integral intensity The basic characteristics of the NC th are very similar to analogous DM ones Among them are magnitudes of their thresholds strong influence of HF-induced striations on their features dependences of their intensity on PW frequency PW power and heating antenna beam position relatively to the geomagnetic field gyro features typical times of their development after PW switch-on generation of these SEE components when a PW frequency is slightly below of F 2 -region critical frequency f 0F2 but an upper hybrid resonance frequency for the PW still remains below f 0F2 The intensity of the NC th as for DM has a maximal level in a PW frequency range from 5 to 7 MHz and it is fast reduced outside of this range The form of NC th spectra is often very similar to the spectral form of DM and its satellites DM1 and DM2 for their low frequency flanks

  20. Time Resolved Spectra of GRBs Simultaneously Detected with BATSE andBeppoSAX WFCs

    NASA Astrophysics Data System (ADS)

    Frontera, Filippo; Amati, Lorenzo; Farinelli, Ruben; Guidorzi, Cristiano; Landi, Raffaella; Titarchuk, Lev; in't Zand, Jean J. M.

    We will discuss preliminary results of a systematic investigation devoted to study the time resolved broad-band spectra of the prompt emission of a sample of GRBs. These events were simultaneously detected with the BeppoSAX WFCs and the BATSE instrument aboard CGRO. We will discuss the fit of these spectra with the Band function, with a blackbody plus a power-law model, and with a Comptonization model developed by Titarchuk & Farinelli (2011, to be submitted).

  1. Modelling blazar radiation spectra Electron injection break and pair content of quasar jets

    E-print Network

    M. Blazejowski; M. Sikora; R. Moderski; T. Bulik

    1999-10-22

    We study the dependence of nonthermal radiation spectra in OVV quasars on location of the low energy break in the electron/positron injection function. We show that the high energy spectra produced during the outbursts are presumably superposed from two components, one resulting from Comptonization of emission lines, which dominates at MeV-GeV energies, and the other resulting from Comptonization of infrared radiation, which dominates in the X-ray band.

  2. Modeling Spectra of the North and South Jovian X-ray Auroras

    SciTech Connect

    Kharchenko, Vasili A; Bhardwaj, Anil; Dalgarno, A.; Schultz, David Robert; Stancil, Phillip C.

    2008-08-01

    Spectra of Jovian X-ray auroras observed from the North and South poles with the Chandra X-ray telescope are analyzed and compared with predicted spectra of the charge-exchange mechanism. To determine the theoretical spectra of Jovian X-ray auroras, we model numerically the collisionally induced evolution of energy and charge distributions of Oq+ and Sq+ ions, precipitating into the Jovian atmosphere. Monte Carlo simulations of the energy and charge relaxation of the precipitating ions are carried out with updated cross-sections of the ion stripping, electron capture, and gas-ionization collisions. X-ray and Extreme Ultraviolet (EUV) spectra of cascading radiation induced by individual energetic sulfur and oxygen ions are calculated, and relative intensities of X-ray emission lines are determined. Synthetic spectra of X-ray and EUV photons are computed at different initial kinetic energies and compositions of ion-precipitating fluxes. Theoretical spectra with adjustable initial energies and relative fraction of sulfur and oxygen ions are shown to be in good agreement with the spectra of X rays detected from the South and North polar regions. The abundances and initial energies of the precipitating ions are inferred by comparing synthetic and observed X-ray spectra. Comparisons are performed independently for the North and South pole emissions. Abundances of the precipitating sulfur ions are found to be four to five times smaller than those of oxygen ions, and averaged ion energies are determined to lie between 1 and 2 MeV/amu. Slightly different ion flux compositions are found to describe the observed spectra of X-ray emission from the North and South poles.

  3. Broad iron K emission line and spectral variability of the Seyfert 2 galaxy IRAS 18325-5926

    NASA Technical Reports Server (NTRS)

    Iwasawa, K.; Fabian, A. C.; Mushotsky, R. F.; Brandt, W. N.; Awaki, H.; Kunieda, H.

    1996-01-01

    A very broad iron K alpha emission line is observed in the Advanced Satellite for Cosmology and Astrophysics (ASCA) spectrum of the Seyfert 2 galaxy IRAS 18325-5926. The line profile is peaked at 6.9 keV and skewed down to 4 keV. The breadth and shift of the line energy can be interpreted by Doppler and relativistic effects in a cold accretion disk about a black hole with a intermediate inclination of between 40 and 50 deg. The steep spectral slope and the fast variability on a timescale of 10(exp 4) s are confirmed for this object. A study of spectral variability reveal that the X-ray flux change mainly occurred above 1 keV and the soft X-ray component below 1 keV appears to be less variable or constant and should lie outside of the nuclear obscuration.

  4. Five-element Johann-type x-ray emission spectrometer with a single-photon-counting pixel detector

    SciTech Connect

    Kleymenov, Evgeny; Bokhoven, Jeroen A. van; David, Christian; Janousch, Markus; Studer, Marco; Willimann, Markus; Bergamaschi, Anna; Henrich, Beat; Nachtegaal, Maarten; Glatzel, Pieter; Alonso-Mori, Roberto

    2011-06-15

    A Johann-type spectrometer with five spherically bent crystals and a pixel detector was constructed for a range of hard x-ray photon-in photon-out synchrotron techniques, covering a Bragg-angle range of 60 deg. - 88 deg. The spectrometer provides a sub emission line width energy resolution from sub-eV to a few eV and precise energy calibration, better than 1.5 eV for the full range of Bragg angles. The use of a pixel detector allows fast and easy optimization of the signal-to-background ratio. A concentration detection limit below 0.4 wt% was reached at the Cu K{alpha}{sub 1} line. The spectrometer is designed as a modular mobile device for easy integration in a multi-purpose hard x-ray synchrotron beamline, such as the SuperXAS beamline at the Swiss Light Source.

  5. Thermodynamic interpretation of multiparticle emission in relativistic heavy ion collisions

    SciTech Connect

    Gleeson, A.M.; Raha, S.

    1980-02-01

    The scattering of the heavy ion Ne from NaF is analyzed at relativistic energy. The spectra of the emission fragments are studied for evidence of a thermodynamic-hydrodynamic collective motion. The spectra of pion, deuteron, and proton emission are fitted for fixed beam and target. The fit is consistent with an interpretation of an expanding hot fluid of interacting nucleons. 2 figures.

  6. Spectra of comet P/Halley at R = 4 - 8 AU

    NASA Technical Reports Server (NTRS)

    Wehinger, Peter A.; Kleine, Marvin; Wyckoff, Susan; Tegler, Stephen C.; Belton, Michael S. J.

    1991-01-01

    Spectra of Comet Halley (lambda lambda = 3400-6500 A) were acquired at pre- and post-perihelion distances of 4.8 AU on 1985 Feb. 17 (Coma V equals 18.9 mag) and 1987 Feb. 1 (coma V = 15.9 mag) using the 4.5-m Multiple-Mirror Telescope (MMT) and the CTIO 4.0-m telescope, respectively. The CN(0,0) violet system band flux at 4.8 AU was approx. 15 times greater at the post-perhelion phase compared to pre-perihelion. Additional post-perihelion spectra, obtained on 1986 Nov. 28 to 30 with the MTT, showed CN(0,0) and very weak C3 4040 A emission. The MMT data are one-dimensional spectra (aperture: 5 arc sec diameter) obtained with an intensified Reticon while the CTIO data are two-dimensional spectra (slit length = 280 arc sec) obtained with a 2D-Frutti photon counting system. Extended CN(0,0) emission was detected in the 1987 Feb. 1 (at 4.8 AU) spectra to a distance of at least 70 arc sec in the solar and anti-solar directions. Additional CCD spectra obtained with the KPNO 2.2-meter telescope on 1988 Feb. 20 (at 7.9 AU) show scattered solar continuum approx. 32 arc sec diameter. However, no emission features were detected at 7.9 AU.

  7. Two Types of Soft X-ray Spectra in Cataclysmic Variables

    NASA Technical Reports Server (NTRS)

    White, Nicholas E. (Technical Monitor); Mukai, K.; Kinkhabwala, A.; Peterson, J. R.; Kahn, S. M.; Paerels, F.

    2002-01-01

    We present results of analyses of Chandra HETG soft X-ray spectra (Lambda = 1.5-25 A) of seven cataclysmic variables. We find that these spectra divide unambiguously into two distinct types. Spectra of the first type, consisting of EX Hya, V603 Aql, U Gem, and SS Cyg, are remarkably well fit by a simple cooling flow model, which assumes only steady-state isobaric radiative cooling. This model has only two free parameters, the maximum temperature, kT(sub max), which provides a rough measurement of the depth of the potential well, and the overall normalization, which provides a highly precise measurement of the total accretion rate. Spectra of the second type, consisting of V1223 Sgr, A Psc, and GK Per, are grossly inconsistent with a simple cooling flow model. They instead exhibit a hard continuum, and, in addition, show strong H-like and He-like ion emission but little Fe L-shell emission, which is consistent with expectations for line emission from a photoionized plasma. Using a simple photoionization model, we argue that the observed line emission for these sources can be driven entirely by the hard continuum. The physical significance of these two distinct types of X-ray spectra is also explored.

  8. Hierarchical analysis of molecular spectra

    SciTech Connect

    Davis, M.J.

    1996-03-01

    A novel representation of molecular spectra in terms of hierarchical trees has proven to be an important aid for the study of many significant problems in gas-phase chemical dynamics. Trees are generated from molecular spectra by monitoring the changes that occur in a spectrum as resolution is changed in a continuous manner. A tree defines a genealogy among all lines of a spectrum. This allows for a detailed understanding of the assignment of features of a spectrum that may be difficult to obtain any other way as well as an understanding of intramolecular energy transfer time scales, mechanisms, and pathways. The methodology has been applied to several problems: transition state spectroscopy, intramolecular energy transfer in highly excited molecules, high-resolution overtone spectroscopy, and the nature of the classical-quantum correspondence when there is classical chaos (``quantum chaos``).

  9. BPS Spectra, Barcodes and Walls

    E-print Network

    Cirafici, Michele

    2015-01-01

    BPS spectra give important insights into the non-perturbative regimes of supersymmetric theories. Often from the study of BPS states one can infer properties of the geometrical or algebraic structures underlying such theories. In this paper we approach this problem from the perspective of persistent homology. Persistent homology is at the base of topological data analysis, which aims at extracting topological features out of a set of points. We use these techniques to investigate the topological properties which characterize the spectra of several supersymmetric models in field and string theory. We discuss how such features change upon crossing walls of marginal stability in a few examples. Then we look at the topological properties of the distributions of BPS invariants in string compactifications on compact threefolds, used to engineer black hole microstates. Finally we discuss the interplay between persistent homology and modularity by considering certain number theoretical functions used to count dyons i...

  10. Ultraviolet fluorescence spectra of fingerprints.

    PubMed

    Saitoh, Naoki; Akiba, Norimitsu

    2005-05-01

    We have studied inherent fluorescence spectra and imaging of fingerprints in the deep ultraviolet (UV) region with a nanosecond-pulsed Nd-YAG laser system that consists of a tunable laser, a cooled CCD camera, and a grating spectrometer. In this paper, we have studied UV fluorescence spectra of fingerprints under 266-nm illumination. Fluorescence spectra of fingerprints have two main peaks, around 330 nm (peak A) and 440 nm (peak B). At first, when a fingerprint has just been pressed, peak A is dominant. However, its intensity reduces as the total illumination time increases. On the other hand, peak B is weak at first. It appears after enough 266-nm illumination and its intensity increases as time elapses. After 3 h of illumination, peak A almost diminishes and peak B becomes dominant. By leaving the fingerprint under a fluorescent lamp in a room without laser illumination, peak A can be restored partly, while the intensity of peak B still increases. Time-resolved fluorescence spectra were also measured for these two peaks. The lifetime of each peak is 2.0 nsec (peak A) and 6.2 nsec (peak B) on average. Both peaks seem to consist of several components with different lifetimes. In the case of peak A, the 330-nm peak decays fast and a new component at 360 nm becomes dominant when the delay time exceeds 20 nsec. In the case of peak B, unlike peak A, no clear peak separation is observed, but the peak position seems to move from 440 to 460 nm when the delay time becomes larger. PMID:15870848

  11. Moments of ambient Doppler spectra

    SciTech Connect

    Lehman, S.K.

    1993-03-23

    The author studied the first four moments (center of mass, standard deviation, skew, and kurtosis) of the Doppler spectra in ambient regions of LLNL-Hughes real aperture radar data collected during WCSEX91--92. The goal was to correlate trends in the moments with wind velocity and direction. Although the center of mass appears to increase when the wind is blowing into the radar antenna, no other conclusions have been drawn from the higher order moments.

  12. Mercury Emissions

    EPA Science Inventory

    This indicator presents nationwide mercury emissions data for 1990 to 1993, 2002, and 2005. This information improves understanding of how mercury emissions, which over time eventually deposit on land and water and cause mercury to accumulate in the food web, have changed in r...

  13. CARBON STARS WITH INFRARED SPECTRA IN GROUP P OF THE IRAS/LRS DATABASE

    SciTech Connect

    Chen, P. S.

    2012-10-01

    Sources with infrared spectra in Group P of the IRAS/LRS database all show polycyclic aromatic hydrocarbon features. They are often planetary nebulae, H II regions, reflection/dark nebulae, Wolf-Rayet stars, or external galaxies. However, we noted that some carbon stars are also included in this group. We searched for and investigated all infrared spectra in Group P of the IRAS/LRS database. Finally, we found 11 previously known carbon stars and identified 8 new candidate carbon stars in Group P. Infrared spectra of these stars may present the 11.2 {mu}m SiC emission features indicative of their carbon-rich properties.

  14. Calculation of delayed-neutron energy spectra in a QRPA-Hauser-Feshbach model

    SciTech Connect

    Kawano, Toshihiko; Moller, Peter; Wilson, William B

    2008-01-01

    Theoretical {beta}-delayed-neutron spectra are calculated based on the Quasiparticle Random-Phase Approximation (QRPA) and the Hauser-Feshbach statistical model. Neutron emissions from an excited daughter nucleus after {beta} decay to the granddaughter residual are more accurately calculated than in previous evaluations, including all the microscopic nuclear structure information, such as a Gamow-Teller strength distribution and discrete states in the granddaughter. The calculated delayed-neutron spectra agree reasonably well with those evaluations in the ENDF decay library, which are based on experimental data. The model was adopted to generate the delayed-neutron spectra for all 271 precursors.

  15. BATSE Observations of Gamma-Ray Burst Spectra. Part 3; Low-Energy Behavior of Time-Averaged Spectra

    NASA Technical Reports Server (NTRS)

    Preece, R. D.; Briggs, M. S.; Pendleton, G. N.; Paciesas, W. S.; Matteson, J. L.; Band, D. L.; Skelton, R. T.; Meegan, C. A.

    1996-01-01

    We analyze time-averaged spectra from 86 bright gamma-ray bursts from the first 5 years of the Burst And Transient Source Experiment (BATSE) on board the Compton Gamma Ray Observatory to determine whether the lowest energy data are consistent with a standard spectra form fit to the data at all energies. The BATSE Spectroscopy Detectors have the capability to observe photons as low as 5 keV. Using the gamma-ray burst locations obtained with the BATSE Large Area Detectors, the Spectroscopy Detectors' low-energy response can be modeled accurately. This, together with a postlaunch calibration of the lowest energy Spectroscopy Detector discriminator channel, which can lie in the range 5-20 keV, allows spectral deconvolution over a broad energy range, approx. 5 keV to 2 MeV. The additional coverage allows us to search for evidence of excess emission, or for a deficit, below 20 keV. While no burst has a significant (greater than or equal to 3 sigma) deficit relative to a standard spectra model, we find that 12 bursts have excess low-energy emission, ranging between 1.2 and 5.8 times the model flux, that exceeds 5 sigma in significance. This is evidence for an additional low-energy spectral component in at least some bursts, or for deviations from the power-law spectral form typically used to model gamma-ray bursts at energies below 100 keV.

  16. The intrinsic fluorescence spectra of selected pollen and fungal spores

    NASA Astrophysics Data System (ADS)

    O'Connor, David J.; Iacopino, Daniela; Healy, David A.; O'Sullivan, Daniel; Sodeau, John R.

    2011-11-01

    Primary Biological Aerosol Particles (PBAP) are ubiquitous in the atmosphere and recently the measurement of their fluorescence properties, in real-time, have been used to discriminate biological (particularly pollen and fungal spores) from non-biological particles in ambient environments. In the laboratory study reported here, the fluorescence spectra of several types of PBAP have been measured at 370 nm excitation. By this means, instructive spectroscopic signatures have been obtained for the various botanical families and orders studied here. All the spore emission spectra were shown to closely resemble each other: they display peaks at 415 nm and broad continua between 450 and 500 nm. In comparison the pollen gave discriminating spectra. For example, the Betulaceae exhibit three distinctive and virtually identical features at 420 nm, 465 nm and 560 nm. The conifers ( Pinus sylvestris, Picea abies and Taxus baccata) pollen also display these features although with differing relative intensity ratios compared to the Betulaceae. Importantly, the grasses not only show the common pollen spectral features but also a sharp band at 675-680 nm: this observation demonstrates the presence of chlorophyll-a. The latter fluorescence signal could, in principle, be used in the real-time atmospheric identification of grass pollen, which are known carriers of aeroallergens. A PCA analysis was also conducted on the obtained spectra and demonstrated that grass pollen were separable from the other samples under investigation.

  17. Fluorescence spectra of cultured normal and malignant lung cells

    NASA Astrophysics Data System (ADS)

    Atif, M.; AlSalhi, M. S.; AlObiadi, A. A.; Aldwayyan, A. S.

    2012-08-01

    Fluorescence Spectroscopy has emerged as a new modality to characterize physicochemical properties of biomolecules. The biomolecules have certain photophysical properties based on their molecular structure and these properties have been considered as useful parameters to monitor alterations in the functional, morphological and micro environmental changes in the cells and tissues. In this study the fluorescence emission spectra of normal and malignant lung cells were recorded for different excitation wavelengths: 230, 300, 340, and 450 nm, corresponding to the absorption of tyrosine, tryptophan, collagen or elastin, Nicotinamide adenine dinucleotide (NADH) and flavin adeno dinucleotide (FAD). Similarly excitation spectra were also recorded at 340 nm. The emission profiles showed considerable difference between the malignant and normal cells with the malignant cells having more fluorescence intensity than that of normal cells keeping emission at 340 nm. Our study had shown the discriminating features between normal and carcinoma cells lines because of higher concentration of tryptophan (1.5 times), NADH (3 times), and flavin (4 times) in carcinoma cell lines.

  18. Near Infrared Spectra of the Orion Bar

    E-print Network

    Marconi, A; Natta, A; Walmsley, C M; Spazio, D A S; Firenze, U; Arcetri, O A

    1997-01-01

    We have used the LONGSP spectrometer on the 1.5-m TIRGO telescope to obtain long slit spectra in the J, H, and K wavelength bands towards two positions along the Orion bar. These data have been supplemented with images made using the ARNICA camera mounted on TIRGO as well as with an ESO NTT observation carried out by Dr A. Moorwood. We detect a variety of transitions of hydrogen, helium, OI, FeII, FeIII, and H_2 . From our molecular hydrogen data, we conclude that densities are moderate (3-6 10^4 cm^-3) in the layer responsible for the molecular hydrogen emission and give no evidence for the presence of dense neutral clumps. We also find that the molecular hydrogen bar is likely to be tilted by ~10 degrees relative to the line of sight. We discuss the relative merits of several models of the structure of the bar and conclude that it may be split into two structures separated by 0.2-0.3 parsec along the line of sight. It also seems likely to us that in both structures, density increases along a line perpendicu...

  19. A 4.8 hour periodicity in the spectra of Cyg X-3

    NASA Technical Reports Server (NTRS)

    Becker, R. H.; Robinson-Saba, J. L.; Boldt, E. A.; Holt, S. S.; Pravdo, S. H.; Serlemitsos, P. J.; Swank, J. H.

    1978-01-01

    The X-ray spectra from three observations of the X-ray binary Cyg X-3 by the cosmic X-ray spectroscopy experiment on OSO can be represented by power-law continua with strong iron line emission. Comparisons of spectra taken within the same observation at various phases of the 4.8 hour period reveal a relative excess of low energy X-ray emission near zero phase (i.e. the minimum) of the 4.8 hour modulation. In addition, the centroid of the line emission is observed to vary in phase with the 4.8 hour cycle. The possibility of persistent thermal X-ray emission from material surrounding the binary system is introduced in an effort to account for the observed effects.

  20. Relativistic Effects on Reflection X-ray Spectra of AGN

    SciTech Connect

    Lee, Khee-Gan; Fuerst, Steven V.; Brandwardi-Raymond, Graziella; Wu, Kinwah; Crowley, Oliver; /University Coll. London

    2007-01-05

    We have calculated the reflection component of the X-ray spectra of active galactic nuclei (AGN) and shown that they can be significantly modified by the relativistic motion of the accretion flow and various gravitational effects of the central black hole. The absorption edges in the reflection spectra suffer severe energy shifts and smearing. The degree of distortion depends on the system parameters, and the dependence is stronger for some parameters such as the inner radius of the accretion disk and the disk viewing inclination angles. The relativistic effects are significant and are observable. Improper treatment of the reflection component of the X-ray continuum in spectral fittings will give rise to spurious line-like features, which will mimic the fluorescent emission lines and mask the relativistic signatures of the lines.

  1. Radio Spectra from Shock Accelerated Electrons in the Cluster Outskirts

    NASA Astrophysics Data System (ADS)

    Kang, Hyesung; Ryu, Dongsu

    2015-08-01

    Using diffusive shock acceleration (DSA) simulations, we have calculated the acceleration of cosmic-ray electrons and the ensuing radio synchrotron emission at weak spherical shocks that are expected to form in the outskirts of galaxy clusters. We demonstrate that, at decelerating spherical shocks, the volume integrated spectra of both electrons and radiation deviate from the test-particle power-laws predicted for constant planar shocks, because the shock compression ratio and the flux of injected electrons decrease in time. If the postshock magnetic field strength is about 5 microgauss, at the shock age of around 50-100 Myr, the volume-integrated radio spectrum steepens gradually with the spectral index from ?inj to ?inj+0.5 over 0.1-10 GHz, where ?inj is the injection index at the shock position expected from the DSA theory. We suggest that such gradual steepening could explain the curved radio spectra of some radio relics found in galaxy clusters.

  2. Neutron spectra due (13)N production in a PET cyclotron.

    PubMed

    Benavente, J A; Vega-Carrillo, H R; Lacerda, M A S; Fonseca, T C F; Faria, F P; da Silva, T A

    2015-05-01

    Monte Carlo and experimental methods have been used to characterize the neutron radiation field around PET (Positron Emission Tomography) cyclotrons. In this work, the Monte Carlo code MCNPX was used to estimate the neutron spectra, the neutron fluence rates and the ambient dose equivalent (H*(10)) in seven locations around a PET cyclotron during (13)N production. In order to validate these calculations, H*(10) was measured in three sites and were compared with the calculated doses. All the spectra have two peaks, one above 0.1MeV due to the evaporation neutrons and another in the thermal region due to the room-return effects. Despite the relatively large difference between the measured and calculated H*(10) for one point, the agreement was considered good, compared with that obtained for (18)F production in a previous work. PMID:25699664

  3. Near-Infrared Spectra of Ultraluminous Infrared Galaxies

    E-print Network

    T. W. Murphy, Jr.; B. T. Soifer; K. Matthews; J. R. Kiger; L. Armus

    1999-09-14

    Near infrared spectra with resolution R ~ 1100 in the rest wavelength range 1.8-2.2 microns have been obtained for a complete sample of 33 ultraluminous infrared galaxies. Of the 33 objects observed, 2 show evidence of a central AGN through either a broad Paschen-alpha line or emission in the 1.963 micron fine structure of [Si VI]. In the median spectrum of the remaining 31 objects, the lines present are recombination lines of Hydrogen, neutral Helium, vibration-rotation lines of H_2, and [Fe II]. There is no indication of AGN activity in the median spectrum, either through broad atomic recombination lines or high ionization lines. No trends in luminosity are apparent when subsets of the 31 non-AGN ULIRGs are binned by luminosity and median combined. When secondary nuclei exist in ULIRGs, they typically have spectra very much like those seen in the primary nuclei.

  4. Infrared Spectra of Polycyclic Aromatic Hydrocarbons (PAHs)

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Bakes, E. L. O.

    2000-01-01

    We have computed the synthetic infrared spectra of some polycyclic aromatic hydrocarbons containing up to 54 carbon atoms. The species studied include ovalene, circumcoronene, dicoronylene, and hexabenzocoronene. We report spectra for anions, neutrals, cations, and multiply charged cations.

  5. Quantitative Analysis of the Resolved X-ray Emission Line Profiles of O Stars

    E-print Network

    Cohen, David

    -loss rates OUTLINE #12; Pup (O4 I) 10 Å 20 Å N VO VII O VIII Ne X Si XIV Fe XVII Ne IX Mg XII Globally, O.swarthmore.edu/~cohen/presentations/CfA_11jun07.pdf #12;1. Chandra spectra: emission lines are broad and asymmetric 2. Hot-star X star X-ray spectra look like coronal spectra #12;But the emission lines are quite broad Ne X Ne IX Fe

  6. Camera artifacts in IUE spectra

    NASA Technical Reports Server (NTRS)

    Bruegman, O. W.; Crenshaw, D. M.

    1994-01-01

    This study of emission line mimicking features in the IUE cameras has produced an atlas of artifiacts in high-dispersion images with an accompanying table of prominent artifacts and a table of prominent artifacts in the raw images along with a medium image of the sky background for each IUE camera.

  7. Electron Impact Induced VUV Emission from Argon

    NASA Astrophysics Data System (ADS)

    Young, J. A.; Malone, C. P.; Johnson, P. V.

    2011-10-01

    Emission intensity and spectra are important tools for diagnosing plasma properties such as electron temperature and neutral density. In order to properly interpret emissions from low-density plasmas, accurate cross sections are needed, particularly low energy electron-impact cross sections. Of interest are the cross sections for Argon, a common species used in industrial and lighting applications. In this paper, we present recent measurements of electron-impact induced VUV emissions from Ar using a magnetically collimated monoenergetic beam of electrons and a 0.2m spectrometer. Specifically, we present emission excitation functions for both Ar I(1048 Å) and Ar I(1066 Å) emissions. Similarities and differences between current results and previously published emission results will be discussed. Also discussed will be the relation to recent electron energy loss results.

  8. 5 – 14 ?m Spitzer spectra of primitive asteroid families

    NASA Astrophysics Data System (ADS)

    Landsman, Zoe A.; Licandro, Javier; Campins, Humberto; Ziffer, Julie; de Prá, Mário

    2015-11-01

    Compositional studies of primitive asteroid families provide constraints on the physical and chemical environment of the solar nebula and the evolution of the asteroid belt. Spectroscopic studies in the visible and near-infrared have shown spectral diversity between primitive families. Our goal is to better constrain the composition of two primitive families with very different ages: Themis (~2.5 Gyr) and Veritas (~8 Myr). We analyzed 5 – 14 ?m Spitzer Space Telescope spectra of a total of 18 asteroids, nine from each family. We report the presence of a broad 10-?m emission feature, attributed to a layer of fine-grained silicates, in the spectra of all nine Themis asteroids and six of nine Veritas asteroids in our sample. Spectral contrast in statistically significant detections of the 10-?m feature ranges from 1% ± 0.1% to 8.5% ± 0.9%. Comparison with the spectra of primitive meteorites (McAdam et al. 2015, Icarus, 245, 320) suggests asteroids in both families are similar to meteorites with lower abundances of phyllosilicates. We used the Near-Earth Asteroid Thermal Model to derive diameters, beaming parameters and albedos for our sample. Asteroids in both families have beaming parameters near unity and geometric albedos in the range 0.06 ± 0.01 to 0.14 ± 0.02. We find that contrast of the silicate emission feature is not correlated with asteroid diameter; however, higher 10-?m contrast may be associated with flatter spectral slopes in the near-infrared. The spectra of both families suggest icy bodies with some amount of fine-grained silicates, but with coarser grains or denser surface structure than Trojan asteroids and comets.

  9. Vibronic spectra of perylene bisimide oligomers: effects of intermolecular charge-transfer excitation and conformational flexibility.

    PubMed

    Gao, Fang; Zhao, Yi; Liang, WanZhen

    2011-03-31

    We have recently presented a theoretical study on the temperature-dependent absorption and photoluminescence spectroscopy of rubrene multichromophores by combining the time-dependent long-range-corrected density functional theory with the Frenkel exciton model (Gao; et al. J. Phys. Chem. A2009, 113, 12847). The spectra of rubrene multichromophores up to heptamers have been calculated and the effects of exciton-phonon coupling and temperature on the photophysical properties of both H- and J-aggregated oligomers were addressed. However, in that work the contribution of intermolecular charge-transfer excitons (CTEs) to vibronic spectra was not addressed. Here we take into account the effect of CTEs for the absorption and emission spectra of the aggregated perylene bisimide (PBI) oligomers in order to have a quantitative explanation to the experimental absorption and emission spectra of the PBI dyes. The role of intermolecular CTEs is discussed for different intermolecular orientations and distances. The simulations demonstrate that the contribution of CTEs becomes significant when the intermolecular distance is less than 4.5 Å for the ?-? stacked PBI aggregates, and the mixed exciton model is prerequisite to explain the experimentally observed red-shift of the absorption spectra in this case. The large Stokes shift of the emission spectra can be reproduced by our model, and it is induced by the asymmetric nature of the lowest excitonic state of the H-aggregated oligomers. The experimentally observed broad emission bands come from two species with different conformations. As for J-aggregated PBI oligomers, the interactions of FEs induce the red-shift and the increase of the relative intensity of 0-0 peak of the absorption spectra with more aggregated units. PMID:21384839

  10. Visible emission from Ag+ exchanged SOD zeolites

    NASA Astrophysics Data System (ADS)

    Lin, H.; Imakita, K.; Fujii, M.; Prokof'ev, V. Yu.; Gordina, N. E.; Saïd, B.; Galarneau, A.

    2015-09-01

    Broad visible emissions dominant at green or red have been observed for the thermally-treated Ag+ exchanged SOD zeolites, determined by the Ag+ loading contents and the excitation wavelengths. Contrary to the notable reversible green/red dominant emission evolution in the Ag+ exchanged LTA zeolites upon hydration/dehydration in air (or water vapor)/vacuum, emission spectra of the Ag+ exchanged SOD zeolites are insensitive to the environmental change. This is most probably due to the difficult H2O permeation in SOD zeolites in comparison with LTA zeolites. By combining the environment dependent emission spectra of the Ag+ exchanged LTA and SOD zeolites, we proposed the following emission mechanisms for Ag+ exchanged LTA and SOD zeolites: the green emission is due to the transition from ligand-to-metal (framework O2- --> Ag+) charge transfer state to the ground state and the red emission is due to the transition from the metal-metal (Ag+-Ag+) charge transfer state to the ground state. The insensitive environment dependent emission characteristics of Ag+ exchanged SOD zeolites may have potential applications as robust phosphors.

  11. Visible emission from Ag(+) exchanged SOD zeolites.

    PubMed

    Lin, H; Imakita, K; Fujii, M; Prokof'ev, V Yu; Gordina, N E; Saïd, B; Galarneau, A

    2015-10-14

    Broad visible emissions dominant at green or red have been observed for the thermally-treated Ag(+) exchanged SOD zeolites, determined by the Ag(+) loading contents and the excitation wavelengths. Contrary to the notable reversible green/red dominant emission evolution in the Ag(+) exchanged LTA zeolites upon hydration/dehydration in air (or water vapor)/vacuum, emission spectra of the Ag(+) exchanged SOD zeolites are insensitive to the environmental change. This is most probably due to the difficult H2O permeation in SOD zeolites in comparison with LTA zeolites. By combining the environment dependent emission spectra of the Ag(+) exchanged LTA and SOD zeolites, we proposed the following emission mechanisms for Ag(+) exchanged LTA and SOD zeolites: the green emission is due to the transition from ligand-to-metal (framework O(2-)? Ag(+)) charge transfer state to the ground state and the red emission is due to the transition from the metal-metal (Ag(+)-Ag(+)) charge transfer state to the ground state. The insensitive environment dependent emission characteristics of Ag(+) exchanged SOD zeolites may have potential applications as robust phosphors. PMID:26349525

  12. Black Holes from Blue Spectra

    E-print Network

    James E. Lidsey; B. J. Carr; J. H. Gilbert

    1994-06-09

    Blue primordial power spectra with a spectral index $n>1$ can lead to a significant production of primordial black holes in the very early Universe. The evaporation of these objects leads to a number of observational consequences and a model independent upper limit of $n \\approx 1.4$. In some cases this limit is strengthened to $n=1.3$. Such limits may be employed to define the boundary to the region of parameter space consistent with generalized inflationary predictions. [To appear in Proceedings of the CASE WESTERN CMB WORKSHOP, April 22-24 1994. Figures available on request from J.H.Gilbert@qmw.ac.uk

  13. Action spectra for photosynthetic inhibition

    NASA Technical Reports Server (NTRS)

    Caldwell, M. M.; Flint, S.; Camp, L. B.

    1981-01-01

    The ultraviolet action spectrum for photosynthesis inhibition was determined to fall between that of the general DNA action spectrum and the generalized plant action spectrum. The characteristics of this action spectrum suggest that a combination of pronounced increase in effectiveness with decreasing wavelength, substantial specificity for the UV-B waveband, and very diminished response in the UV-A waveband result in large radiation amplification factors when the action spectra are used as weighting functions. Attempted determination of dose/response relationships for leaf disc inhibition provided inconclusive data from which to deconvolute an action spectrum.

  14. An Interpretation of Banded Magnetospheric Radio Emissions

    NASA Technical Reports Server (NTRS)

    Benson, Robert F.; Osherovich, V. A.; Fainberg, J.; Vinas, A. F.; Ruppert, D. R.; Vondrak, Richard R. (Technical Monitor)

    2000-01-01

    Recently-published Active Magnetospheric Particle Tracer Explorer/Isothermal Remanent Magnetization (AMPTE/IRM) banded magnetospheric emissions, commonly referred to as '(n + 1/2)f(sub ce)' emissions where f(sub ce) is the electron gyrofrequency, are analyzed by treating them as analogous to sounder-stimulated ionospheric emissions. We show that both individual AMPTE/IRM spectra of magnetospheric banded emissions, and a statistically-derived spectra observed over the two-year lifetime of the mission, can be interpreted in a self-consistent manner. The analysis, which predicts all spectral peaks within 4% of the observed peaks, interprets the higher-frequency emissions as due to low group-velocity Bernstein-mode waves and the lower-frequency emissions as eigen modes of cylindrical-electromagnetic-plasma-oscillations. The demarcation between these two classes of emissions is the electron plasma frequency f(sub pe), where an emission is often observed. This f(sub pe), emission is not necessarily the strongest. None of the observed banded emissions were attributed to the upper-hybrid frequency. We present Alouette-2 and ISIS-1 plasma-resonance data, and model electron temperature (T(sub e)) values, to support the argument that the frequency-spectrum of ionospheric sounder-stimulated emissions is not strongly temperature dependent and thus that the interpretation of these emissions in the ionosphere is relevant to other plasmas (such as the magnetosphere) where N(sub e) and T(sub e) can be quite different but where the ratio f(sub pe)/f(sub ce) is identical.

  15. High Resolution Spectra of Novae and the Quadratic Zeeman Effect

    E-print Network

    Robert Williams; Elena Mason

    2006-02-27

    High resolution spectra of novae after outburst reveal distinctive characteristics in the line profiles and intensities. The higher Balmer lines are often broader than the lower members of the series, and the relative profiles and intensities of the [O I] \\lambda\\lambda6300, 6364 doublet differ from normal values. We suggest these features may be caused by the Quadratic Zeeman Effect from magnetic fields exceeding B=10^6 gauss. Taken together the emission and absorption lines point to multiple origins for the ejecta on both the erupting white dwarf and the cool secondary star.

  16. New molecular ions in spectra of comet P/Halley

    NASA Technical Reports Server (NTRS)

    Wyckoff, S.; Wehinger, P. A.; Spinrad, Hyron; Belton, M. J. S.

    1986-01-01

    Spectroscopic observations (4000 to 7000 A) were obtained of comet P/Halley near the time of the spacecraft encounters in March 1986. Molecular ion emission features were observed in the long-slit CCD spectra. Additional spectroscopic observations obtained in April 1986 confirm the presence of many new ion features in the plasma tail. It is proposed that CO2(+) be identified with the new features in the 4000 to 4350 A region. The other unidentified ion features may be attributable to a single ion species.

  17. High dispersion far ultraviolet spectra of cool stars

    NASA Technical Reports Server (NTRS)

    Stencel, R. E.; Linsky, J. L.; Ayres, T. R.; Jordan, C.; Brown, A.; Engvold, O.

    1982-01-01

    Recent far ultraviolet high dispersion spectra of two cool supergiant stars, Beta Dra (G2 Ib) and Alpha Ori (M2 Iab) are examined in the context of current questions regarding stellar chromospheres, coronae and mass loss. These stars show very different outer atmosphere structure. Beta Dra has a geometrically thin transition region with bright emission lines of 100,000 K plasma that are red-shifted, indicating downflow in magnetic flux tubes. By contrast, Alpha Ori has a cool extended chromosphere and circumstellar envelope with large mass loss.

  18. Discovery of Oxygen Kalpha X-ray Emission from the Rings of Saturn

    E-print Network

    Anil Bhardwaj; Ronald F. Elsner; J. Hunter Waite, Jr.; G. Randall Gladstone; Thomas E. Cravens; Peter G. Ford

    2005-05-19

    Using the Advanced CCD Imaging Spectrometer (ACIS), the Chandra X-ray Observatory (CXO) observed the Saturnian system for one rotation of the planet (~37 ks) on 20 January, 2004, and again on 26-27 January, 2004. In this letter we report the detection of X-ray emission from the rings of Saturn. The X-ray spectrum from the rings is dominated by emission in a narrow (~130 eV wide) energy band centered on the atomic oxygen K-alpha fluorescence line at 0.53 keV. The X-ray power emitted from the rings in the 0.49-0.62 keV band is 84 MW, which is about one-third of that emitted from Saturn disk in the photon energy range 0.24-2.0 keV. Our analysis also finds a clear detection of X-ray emission from the rings in the 0.49-0.62 keV band in an earlier (14-15 April, 2003) Chandra ACIS observation of Saturn. Fluorescent scattering of solar X-rays from oxygen atoms in the H2O icy ring material is the likely source mechanism for ring X-rays, consistent with the scenario of solar photo-production of a tenuous ring oxygen atmosphere and ionosphere recently discovered by Cassini.

  19. BPS Spectra, Barcodes and Walls

    E-print Network

    Michele Cirafici

    2015-11-04

    BPS spectra give important insights into the non-perturbative regimes of supersymmetric theories. Often from the study of BPS states one can infer properties of the geometrical or algebraic structures underlying such theories. In this paper we approach this problem from the perspective of persistent homology. Persistent homology is at the base of topological data analysis, which aims at extracting topological features out of a set of points. We use these techniques to investigate the topological properties which characterize the spectra of several supersymmetric models in field and string theory. We discuss how such features change upon crossing walls of marginal stability in a few examples. Then we look at the topological properties of the distributions of BPS invariants in string compactifications on compact threefolds, used to engineer black hole microstates. Finally we discuss the interplay between persistent homology and modularity by considering certain number theoretical functions used to count dyons in string compactifications and by studying equivariant elliptic genera in the context of the Mathieu moonshine.

  20. An RGB approach to extraordinary spectra

    NASA Astrophysics Data System (ADS)

    Grusche, Sascha; Theilmann, Florian

    2015-09-01

    After Newton had explained a series of ordinary spectra and Goethe had pointed out its complementary counterpart, Nussbaumer discovered a series of extraordinary spectra which are geometrically identical and colourwise analogous to Newton’s and Goethe’s spectra. To understand the geometry and colours of extraordinary spectra, the wavelength composition is explored with filters and spectroscopic setups. Visualized in a dispersion diagram, the wavelength composition is interpreted in terms of additive colour mixing. Finally, all spectra are simulated as the superposition of red, green, and blue images that are shifted apart. This RGB approach makes it easy to understand the complex relationship between wavelengths and colours.

  1. C NMR Spectra (see p S10)

    E-print Network

    Collum, David B.

    S31 1 H and 13 C NMR Spectra (see p S10) NHBn Me Ph 10 #12;S32 1 H and 13 C NMR Spectra (see p S10) NHBn Me Ph 11 #12;S33 1 H and 13 C NMR Spectra (see p S11) NH-i-Pr n-Bu NH-i-Pr n-Bu 12 Me Me 13 #12;S34 1 H and 13 C NMR Spectra (see p S11)NH-i-Pr Me Ph 14 #12;S35 1 H and 13 C NMR Spectra (see p S11

  2. Infrared atmospheric absorption and emission studies

    SciTech Connect

    Van Allen, R.; Murcray, F. )

    1993-01-01

    This paper describes studies of the composition of the atmosphere over Antarctica. Infrared spectra of the atmosphere contain information about the chemical composition and temperature structure. Measurements are made using the sun as a source from McMurdo Station, with measurements of the infrared emission spectrum of the atmosphere from the South Pole. 3 refs., 2 figs.

  3. Femtosecond stimulated emission pumping: Characterization ground state

    E-print Network

    Neumark, Daniel M.

    ­1 vibrational fre- quency, resonance impulsive stimulated Raman scattering RISRS was used to create ground state motion near the bottom of the well. The Fourier transform of the oscillations observed in the FPE spectraFemtosecond stimulated emission pumping: Characterization of the I2 À ground state Martin T. Zanni

  4. Exploring protein solution structure: Second moments of fluorescent spectra report heterogeneity of tryptophan rotamers.

    PubMed

    Gasymov, Oktay K; Abduragimov, Adil R; Glasgow, Ben J

    2015-11-01

    Trp fluorescent spectra appear as a log-normal function but are usually analyzed with ?max, full width at half maximum, and the first moment of incomplete spectra. Log-normal analyses have successfully separated fluorescence contributions from some multi-Trp proteins but deviations were observed in single Trp proteins. The possibility that disparate rotamer environments might account for these deviations was explored by moment spectral analysis of single Trp mutants spanning the sequence of tear lipocalin as a model. The analysis required full width Trp spectra. Composite spectra were constructed using log-normal analysis to derive the inaccessible blue edge, and the experimentally obtained spectra for the remainder. First moments of the composite spectra reflected the site-resolved secondary structure. Second moments were most sensitive for spectral deviations. A novel parameter, derived from the difference of the second moments of composite and simulated log-normal spectra correlated with known multiple heterogeneous rotamer conformations. Buried and restricted side chains showed the most heterogeneity. Analyses applied to other proteins further validated the method. The rotamer heterogeneity values could be rationalized by known conformational properties of Trp residues and the distribution of nearby charged groups according to the internal Stark effect. Spectral heterogeneity fits the rotamer model but does not preclude other contributing factors. Spectral moment analysis of full width Trp emission spectra is accessible to most laboratories. The calculations are informative of protein structure and can be adapted to study dynamic processes. PMID:26119357

  5. TIMEDEPENDENT ELECTRON TRANSPORT AND OPTICAL EMISSIONS IN THE AURORA

    E-print Network

    Peticolas, Laura

    TIME­DEPENDENT ELECTRON TRANSPORT AND OPTICAL EMISSIONS IN THE AURORA A THESIS Presented­DEPENDENT ELECTRON TRANSPORT AND OPTICAL EMISSIONS IN THE AURORA By Laura Marie Peticolas RECOMMENDED: Advisory observed in electron spectra of instruments flying over flickering aurora, are modeled with the time

  6. Vacuum Rabi spectra of a single quantum emitter

    E-print Network

    Ota, Yasutomo; Kumagai, Naoto; Iwamoto, Satoshi; Arakawa, Yasuhiko

    2015-01-01

    We report the observation of the vacuum Rabi splitting of a single quantum emitter by measuring its direct spontaneous emission into free space. We used a semiconductor quantum dot inside a photonic crystal nanocavity, in conjunction with an appropriate cavity design and filtering with a polarizer and an aperture, enabling the extraction of the inherently-weak emitter's signal. The emitter's vacuum Rabi spectra exhibit clear differences to those measured by detecting the cavity photon leakage. Moreover, we observed an asymmetric vacuum Rabi spectrum induced by interference between the emitter and cavity detection channels. Our observations lay the groundwork for accessing various cavity quantum electrodynamics phenomena that manifest themselves only in the emitter's direct spontaneous emission.

  7. Vacuum Rabi Spectra of a Single Quantum Emitter

    NASA Astrophysics Data System (ADS)

    Ota, Yasutomo; Ohta, Ryuichi; Kumagai, Naoto; Iwamoto, Satoshi; Arakawa, Yasuhiko

    2015-04-01

    We report the observation of the vacuum Rabi splitting of a single quantum emitter by measuring its direct spontaneous emission into free space. We use a semiconductor quantum dot inside a photonic crystal nanocavity, in conjunction with an appropriate cavity design and filtering with a polarizer and an aperture, enabling the extraction of the inherently weak emitter's signal. The emitter's vacuum Rabi spectra exhibit clear differences from those measured by detecting the cavity photon leakage. Moreover, we observe an asymmetric vacuum Rabi spectrum induced by interference between the emitter and cavity detection channels. Our observations lay the groundwork for accessing various cavity quantum electrodynamics phenomena that manifest themselves only in the emitter's direct spontaneous emission.

  8. Vacuum Rabi spectra of a single quantum emitter

    E-print Network

    Yasutomo Ota; Ryuichi Ohta; Naoto Kumagai; Satoshi Iwamoto; Yasuhiko Arakawa

    2015-03-06

    We report the observation of the vacuum Rabi splitting of a single quantum emitter by measuring its direct spontaneous emission into free space. We used a semiconductor quantum dot inside a photonic crystal nanocavity, in conjunction with an appropriate cavity design and filtering with a polarizer and an aperture, enabling the extraction of the inherently-weak emitter's signal. The emitter's vacuum Rabi spectra exhibit clear differences to those measured by detecting the cavity photon leakage. Moreover, we observed an asymmetric vacuum Rabi spectrum induced by interference between the emitter and cavity detection channels. Our observations lay the groundwork for accessing various cavity quantum electrodynamics phenomena that manifest themselves only in the emitter's direct spontaneous emission.

  9. Intensity Spectra Versus Response Spectra: Basic Concepts and Applications

    NASA Astrophysics Data System (ADS)

    Sandi, Horea; Borcia, Ioan Sorin

    2011-01-01

    This paper begins with a critical assessment of the concept of macroseismic intensity, on which traditional scales, such as MSK and EMS, are based. The main shortcoming identified is the model's failure to consider the spectral features of ground motion. This omission may lead to erroneous seismic zonation, as shown in the paper. As a result, the model is of little interest to engineers who must design and build safe structures while adopting economical solutions. The paper presents a way to radically improve this situation. The starting point for this approach was the experience of the destructive Vrancea earthquake of 1977.03.04, which made it clear that intensity appears to be different for structures having natural periods pertaining to different spectral domains. The solution proposed to the shortcomings of the traditional intensity concept is postulated on a system of analytical expressions, covering definitions of global intensities, of intensities related to oscillation frequency and of intensities related to a definite spectral band. The latter definition lies at the basis of a definition of discrete intensity spectra. Illustrative applications are presented, in relation to global intensities and to discrete intensity spectra. We then analyze an illustrative case in which the use of traditional macroseismic survey techniques led to erroneous seismic zonation. Finally, some conclusions and recommendations are presented. Based on the authors' long-term experience, we strongly recommend close interaction between seismologists and engineers in working groups and joint projects targeted on radical improvement of the basic concepts of seismic intensity and of specific analysis procedures.

  10. Controlling quantum dot emission by plasmonic nanoarrays.

    PubMed

    Guo, R; Derom, S; Väkeväinen, A I; van Dijk-Moes, R J A; Liljeroth, P; Vanmaekelbergh, D; Törmä, P

    2015-11-01

    Metallic nanoparticle arrays support localized surface plasmon resonances (LSPRs) and propagating surface lattice resonances (SLRs). We study the control of quantum dot (QD) emission coupled to the optical modes of silver nanoparticle arrays, both experimentally and numerically. With a hybrid lithography-functionalization method, the QDs are deposited in the vicinity of the nanoparticles. Directionality and enhancement of the emission are observed in photoluminescence spectra and fluorescence lifetime measurements, respectively. Similar features are also demonstrated in the numerical simulations. The tunable emission of this type of hybrid structures could lead to potential applications in light sources. PMID:26561091

  11. HERSCHEL/SPIRE SUBMILLIMETER SPECTRA OF LOCAL ACTIVE GALAXIES {sup ,}

    SciTech Connect

    Pereira-Santaella, Miguel; Spinoglio, Luigi; Busquet, Gemma; Wilson, Christine D.; Schirm, Maximilien R. P.; Glenn, Jason; Kamenetzky, Julia; Rangwala, Naseem; Isaak, Kate G.; Baes, Maarten; Barlow, Michael J.; Boselli, Alessandro; Cooray, Asantha; Cormier, Diane

    2013-05-01

    We present the submillimeter spectra from 450 to 1550 GHz of 11 nearby active galaxies observed with the SPIRE Fourier Transform Spectrometer (SPIRE/FTS) on board Herschel. We detect CO transitions from J{sub up} = 4 to 12, as well as the two [C I] fine structure lines at 492 and 809 GHz and the [N II]1461 GHz line. We used radiative transfer models to analyze the observed CO spectral line energy distributions. The FTS CO data were complemented with ground-based observations of the low-J CO lines. We found that the warm molecular gas traced by the mid-J CO transitions has similar physical conditions (n{sub H{sub 2}}{approx} 10{sup 3.2}-10{sup 3.9} cm{sup -3} and T{sub kin} {approx} 300-800 K) in most of our galaxies. Furthermore, we found that this warm gas is likely producing the mid-IR rotational H{sub 2} emission. We could not determine the specific heating mechanism of the warm gas, however, it is possibly related to the star formation activity in these galaxies. Our modeling of the [C I] emission suggests that it is produced in cold (T{sub kin} < 30 K) and dense (n{sub H{sub 2}}>10{sup 3} cm{sup -3}) molecular gas. Transitions of other molecules are often detected in our SPIRE/FTS spectra. The HF J = 1-0 transition at 1232 GHz is detected in absorption in UGC 05101 and in emission in NGC 7130. In the latter, near-infrared pumping, chemical pumping, or collisional excitation with electrons are plausible excitation mechanisms likely related to the active galactic nucleus of this galaxy. In some galaxies, few H{sub 2}O emission lines are present. Additionally, three OH{sup +} lines at 909, 971, and 1033 GHz are identified in NGC 7130.

  12. Brane Constructions and BPS Spectra

    NASA Astrophysics Data System (ADS)

    Rastogi, Ashwin

    The object of this work is to exploit various constructions of string theory and M-theory to yield new insights into supersymmetric theories in both four and three dimensions. In 4d, we extend work on Seiberg-Witten theory to study and compute BPS spectra of the class of complete N = 2 theories. The approach we take is based on the program of geometric engineering, in which 4d theories are constructed from compactifications of type IIB strings on Calabi-Yau manifolds. In this setup, the natural candidates for BPS states are D3 branes wrapped on supersymmetric 3-cycles in the Calabi-Yau. Our study makes use of the mathematical structure of quivers, whose representation theory encodes the notion of stability of BPS particles. Except for 11 exceptional cases, all complete theories can be constructed by wrapping stacks of two M5 branes on Riemann surfaces. By exploring the connection between quivers and M5 brane theories, we develop a powerful algorithm for computing BPS spectra, and give an in-depth study of its applications. In particular, we compute BPS spectra for all asymptotically free complete theories, as well as an infinite set of conformal SU(2)k theories with certain matter content. From here, we go on to apply the insight gained from our 4d study to 3d gauge theories. We consider the analog of the M5 brane construction in the case of 3d N = 2 theories: pairs of M5 branes wrapped on a 3-manifold. Using the ansantz of R-flow, we study 3-manifolds consisting of Riemann surfaces fibered over R. When the construction is non-singular, the resulting IR physics is described by a free abelian Chern-Simons theory. The mathematical data of a tangle captures the data of the gauge theory, and the Reidemeister equivalances on tangles correspond to dualities of physical descriptions. To obtain interacting matter, we allow singularities in the construction. By extending the tangle description to these singular cases, we find a set of generalized Reidemeister moves that capture non-trivial mirror symmetries of 3d gauge theories. These results give a geometric origin to these well-known 3d dualities.

  13. Electronic spectra of 5,6-polymethylenethiapyrylium salts and certain oxygen analogs

    SciTech Connect

    Klimenko, S.K.; Evtushenko, I.Ya.; Pronin, A.F.; Stolbova, T.V.; Kharchenko, V.G.

    1985-08-01

    Electronic absorption and emission spectra of substituted 5,6-tri- and 5,6-tetramethylenethiapyrylium salts are examined to determine the influence of the degree and character of substitution of the heterocycle, the size of the condensed alicycle, the nature of the heteroatom and the counterion, and the polarity of the solvent.

  14. A model considering light reabsorption processes to correct in vivo chlorophyll fluorescence spectra in apples.

    PubMed

    Ramos, María E; Lagorio, María G

    2006-05-01

    Chlorophyll-a contained in the peel of Granny Smith apples emits fluorescence upon excitation with blue light. The observed emission, collected by an external detector and corrected by its spectral response, is still distorted by light reabsorption processes taking place in the fruit skin and differs appreciably from the true spectral distribution of fluorescence emerging from chlorophyll molecules in the biological tissue. Reabsorption processes particularly affect the ratio of fluorescence intensities at 680 nm and at 730 nm. A model to obtain the correct spectral distribution of the emission, from the experimental fluorescence recorded at a fluorometer detector and corrected for the detector spectral sensitivity, is developed in the present work. Measurements of the whole fruit reflectance, the peel transmittance and the flesh reflectance allow the calculation of the reabsorption-corrected spectra. The model is validated by comparing the corrected emission spectra with that obtained for a thin layer of apple-peel-chloroplasts, where no reabsorption takes place. It is recommended to correct distortions in emission spectra of intact fruits due to light reabsorption effects whenever a correlation between the physiological state of the fruit and its fluorescence spectra is investigated. PMID:16685329

  15. Infrared Spectra of Young Stars Embedded in the R Coronae Australis Cloud MICHAEL R. MEYER

    E-print Network

    Wilking, Bruce A.

    Department of Physics and Astronomy, University of Missouri­St. Louis, St. Louis, MO 63121; bwilking Australis molecular core. These spectra, which are used to identify young stellar objects in the cloud, include the wavelengths of emission lines from [Fe II] and H2, four of the Brackett series lines, the CO

  16. Study on characteristic intrinsic fluorescence spectra of urine from ovarian cancer patients

    NASA Astrophysics Data System (ADS)

    Lu, Jun; Gao, Shumei; Yang, Youyi; Lu, Xiaohong; Chen, Guoqing

    2007-11-01

    Ovarian cancer has the highest mortality rate among the gynecologic cancers, and it goes undetected because adequate technology does not exist to detect preinvasive or early stage disease. Fluorescence spectroscopy of urine may provide a cost-effective tool to improve precancer detection. This study describes initial investigation of the potential of intrinsic urine fluorescence spectra for detecting early ovarian cancer. Using the Xenon arc lamp to irradiate the urine from ovarian cancer, cervical carcinoma groups and healthy donors, we obtained fluorescence emission spectra. The three groups of samples show different emission spectra peak and fluorescence intensity. Ovarian cancer group has the largest displacement of maximum spectra peak at 380-400nm excitation wavelength. And the fluorescence intensity from ovarian cancer group is significantly higher with the healthy donors and cervical carcinoma group in comparison at the short wave excitation region of 320-360nm, while cervical carcinoma group has higher fluorescence intensity than ovarian cancer group at 380-500nm excitation. Characteristic fluorescence mechanism was studied through comparison of fluorescence spectra and software fitting image. Fluorescence spectra at 440nm excitation is found to be perfectly lorentzian fitted by three characteristic fluorescence peaks, which are originated form coproporphyrin, riboflavin and p-hydroxyphenol derivatives existing in the urine.

  17. Hot Experimental Absorption Spectra of CH_4 in the Pentad and Octad Region

    NASA Astrophysics Data System (ADS)

    Hargreaves, Robert J.; Dulick, Michael; Bernath, Peter F.

    2014-06-01

    We present comprehensive line lists of CH_4 at high temperatures for the pentad and octad region (2400-5000 wn). These spectra improve on our previous emission measurements for this region by using a new quartz sample cell in conjunction with a tube furnace (pictured). Ten temperatures have been recorded from room temperature up to 1000°C and our technique involves the acquisition of four separate Fourier transform infrared spectra at each temperature, thus accounting for both the emission and absorption of the molecule and the cell. By combining these four spectra we obtain true transmission spectra of hot CH_4 in this region. Analysis of this set of spectra enables the production of a line list that includes the position, intensity and empirical lower state energy. Our spectra and line lists can be used directly to model planetary atmospheres and brown dwarfs. Hargreaves, R.J., Beale, C.A., Michaux, L., Irfan, M., & Bernath, P.F. 2012, ApJ, 757, 46

  18. Molecular Emission and Temperature Measurements from Single-Bubble Sonoluminescence

    NASA Astrophysics Data System (ADS)

    Xu, Hangxun; Suslick, Kenneth S.

    2010-06-01

    Single-bubble sonoluminescence (SBSL) spectra in H2O show featureless continuum emission. From an acoustically driven, moving bubble in phosphoric acid (H3PO4), we observe very strong molecular emission from excited OH radicals (˜310nm), which can be used as a spectroscopic thermometer by fitting the experimental SBSL spectra to the OH A?+2-X?2 rovibronic transitions. The observed emission temperature (Tem) ranges from 6200 to 9500 K as the acoustic pressure (Pa) varies from 1.9 to 3.1 bar and from 6000 to >10000K as the dissolved monatomic gas varies over the series from He to Xe.

  19. Graviton spectra in string cosmology

    SciTech Connect

    Galluccio, Massimo; Litterio, Marco; Occhionero, Franco

    1996-08-01

    We propose to uncover the signature of a stringy era in the primordial Universe by searching for a prominent peak in the relic graviton spectrum. This feature, which in our specific model terminates an ?³ increase and initiates an ??? decrease, is induced during the so far overlooked bounce of the scale factor between the collapsing deflationary era (or pre-Big Bang) and the expanding inflationary era (or post-Big Bang). We evaluate both analytically and numerically the frequency and the intensity of the peak and we show that they may likely fall in the realm of the new generation of interferometric detectors. The existence of a peak is at variance with ordinarily monotonic (either increasing or decreasing) graviton spectra of canonical cosmologies; its detection would therefore offer strong support to string cosmology.

  20. Reflectance spectra of primitive chondrites

    NASA Astrophysics Data System (ADS)

    Trigo-Rodríguez, J. M.; Moyano-Cambero, C. E.; Llorca, J.

    2013-05-01

    We are studying a wide sample of pristine carbonaceous chondrites from the NASA Antarctic collection in order to get clues on the physico-chemical processes occurred in the parent bodies of these meteorites. We are obtaining laboratory reflectance spectra of different groups of carbonaceous chondrites, but here we focus in CM and CI chondrites. We discuss the main spectral features that can be used to identify primitive carbonaceous asteroids by remote sensing techniques. Two different spectrometers were used covering the entire 0.3 to 30 ?m electromagnetic window. Only a handful of Near Earth Objects (NEOs) exhibit bands or features clearly associated with aqueous alteration. Among them are the target asteroids of Osiris Rex and Marco Polo-R missions.

  1. Graviton Spectra in String Cosmology

    SciTech Connect

    Galluccio, M.; Occhionero, F.; Litterio, M.

    1997-08-01

    We propose to uncover the signature of a stringy era in the primordial Universe by searching for a prominent peak in the relic graviton spectrum. This feature, which in our specific model terminates an {omega}{sup 3} increase and initiates an {omega}{sup {minus}7} decrease, is induced during the so far overlooked bounce of the scale factor between the collapsing deflationary era (or pre{endash}big bang) and the expanding inflationary era (or post{endash}big bang). The frequency and the intensity of the peak may likely fall in the realm of the new generation of interferometric detectors. The existence of a peak, at variance with ordinarily monotonic graviton spectra, would therefore offer strong support to string cosmology. {copyright} {ital 1997} {ital The American Physical Society}

  2. Schottky spectra and crystalline beams

    NASA Astrophysics Data System (ADS)

    Pestrikov, D. V.

    1996-02-01

    In this paper we revise the current dependence of the Schottky noise power of a cooled proton beam previously measured at NAP-M. More careful study of experimental data indicates a linear decrease in the inverse Schottky noise power with an increase in the beam intensity ( N). The root of this function determines a threshold current which occurs at N = N th ? 1.2 × 10 8 particles. The inspection of measured Schottky spectra shows that this threshold does not correspond to some collective instability of the measured harmonic of the linear beam density. The found value of Nth does not depend on the longitudinal beam temperature. For the case of NAP-M lattice, the study of the spectral properties of the Schottky noise in the crystalline string predicts the current dependence of the equilibrium momentum spread of the beam, which qualitatively agrees with that, recalculated from the NAP-M data.

  3. A reassessment of synchronous fluorescence in the separation of Trp and Tyr contributions in protein emission and in the determination of conformational changes

    NASA Astrophysics Data System (ADS)

    Bobone, Sara; van de Weert, Marco; Stella, Lorenzo

    2014-12-01

    Synchronous fluorescence spectra are performed by simultaneously scanning both the excitation and emission wavelengths, and are widely used to analyze complex mixtures of fluorophores, since they yield narrower bands than traditional excitation or emission spectra. Many recent studies claim that synchronous spectra are able to separate tryptophan (Trp) and tyrosine (Tyr) emission in proteins, and use this approach to analyze conformational transitions induced by ligand binding. Here, the reliability of this method is reassessed, studying mixtures of the two intrinsic protein fluorophores in different solvents, as well as a real protein (bovine serum albumin). Unfortunately, synchronous spectra were found to be unreliable in the separation of Trp and Tyr emission components in proteins. A simple alternative approach based on the deconvolution of emission spectra is presented. In addition, an equation predicting the synchronous spectrum of a specific fluorophore from its excitation and emission spectra has been derived.

  4. First Hard X-Ray Detection of the Non-Thermal Emission Around the Arches Cluster: Morphology and Spectral Studies With NuSTAR

    NASA Technical Reports Server (NTRS)

    Krivonos, Roman A.; Tomsick, John A.; Bauer, Franz E.; Baganoff, Frederick K.; Barriere, Nicolas M.; Bodaghee, Arash; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Grefenstette, Brian W.; Hailey, Charles J.; Harrison, Fiona A.; Hong, JaeSub; Madsen, Kristin K.; Mori, Kaya; Nynka, Melania; Stern, Daniel; Zhang, William W.

    2014-01-01

    The Arches cluster is a young, densely packed massive star cluster in our Galaxy that shows a high level of star formation activity. The nature of the extended non-thermal X-ray emission around the cluster remains unclear. The observed bright Fe K(alpha) line emission at 6.4 keV from material that is neutral or in a low ionization state can be produced either by X-ray photoionization or by cosmic-ray particle bombardment or both. In this paper, we report on the first detection of the extended emission around the Arches cluster above 10 keV with the NuSTAR mission, and present results on its morphology and spectrum. The spatial distribution of the hard X-ray emission is found to be consistent with the broad region around the cluster where the 6.4 keV line is observed. The interpretation of the hard X-ray emission within the context of the X-ray reflection model puts a strong constraint on the luminosity of the possible illuminating hard X-ray source. The properties of the observed emission are also in broad agreement with the low-energy cosmic-ray proton excitation scenario. Key words: cosmic rays - Galaxy: center - ISM: general - X-rays: individual (Arches cluster)

  5. Tritium diagnostics by Balmer-alpha emission

    SciTech Connect

    Skinner, C.H.; Ramsey, A.T.; Johnson, D.W.; Diesso, M.

    1993-02-01

    Spectral line emission from tritium in a plasma may be distinguished from deuterium emission by a small isotope shift. A diagnostic system to measure tritium Balmer-alpha emission from the plasma edge has been installed on TFTR. This system has been used in deuterium plasmas, and the deuterium alpha line profile used as a basis to predict the spectrum at differing tritium concentrations in future D-T runs. The tritium and deuterium lines are partially blended, however, analysis of the predicted D-T spectra by a line fitting program produced estimates of the tritium density that closely matched those input to the spectra, providing confidence that the tritium density can be reliably measured. The spectrum maps the tritium velocity distribution at the plasma edge and will be important for studies of tritium edge physics.

  6. Near Infrared Spectra of the Orion Bar

    E-print Network

    A. Marconi; L. Testi; A. Natta; C. M. Walmsley

    1997-10-04

    We have used the LONGSP spectrometer on the 1.5-m TIRGO telescope to obtain long slit spectra in the J, H, and K wavelength bands towards two positions along the Orion bar. These data have been supplemented with images made using the ARNICA camera mounted on TIRGO as well as with an ESO NTT observation carried out by Dr A. Moorwood. We detect a variety of transitions of hydrogen, helium, OI, FeII, FeIII, and H_2 . From our molecular hydrogen data, we conclude that densities are moderate (3-6 10^4 cm^-3) in the layer responsible for the molecular hydrogen emission and give no evidence for the presence of dense neutral clumps. We also find that the molecular hydrogen bar is likely to be tilted by ~10 degrees relative to the line of sight. We discuss the relative merits of several models of the structure of the bar and conclude that it may be split into two structures separated by 0.2-0.3 parsec along the line of sight. It also seems likely to us that in both structures, density increases along a line perpendicular to the ionization front which penetrates into the neutral gas. We have used the 1.317um OI line to estimate the FUV radiation field incident at the ionization front and find values of 1-3x10^4 greater than the average interstellar field. From [FeII] line measurements, we conclude that the electron density in the ionized layer associated with the ionization front is of order 10^4 cm^-3. Finally, our analysis of the helium and hydrogen recombination lines implies essential coincidence of the helium and hydrogen Stromgren spheres.

  7. Near infrared spectra of the Orion bar

    NASA Astrophysics Data System (ADS)

    Marconi, A.; Testi, L.; Natta, A.; Walmsley, C. M.

    1998-02-01

    We have used the LONGSP spectrometer on the 1.5-m TIRGO telescope to obtain long slit spectra in the J, H, and K wavelength bands towards two positions along the Orion bar. These data have been supplemented with images made using the ARNICA camera mounted on TIRGO as well as with an ESO NTT observation carried out by Dr A. Moorwood. We detect a variety of transitions of hydrogen, helium, OI, FeII, FeIII, and H_2. From our molecular hydrogen data, we conclude that densities are moderate (3-6x 10(4) cm(-3) ) in the layer responsible for the molecular hydrogen emission and give no evidence for the presence of dense neutral clumps. We also find that the molecular hydrogen bar is likely to be tilted by ~ 10 degrees relative to the line of sight. We discuss the relative merits of several models of the structure of the bar and conclude that it may be split into two structures separated by 0.2-0.3 parsec along the line of sight. It also seems likely to us that in both structures, density increases along a line perpendicular to the ionization front which penetrates into the neutral gas. We have used the 1.317mum OI line to estimate the FUV radiation field incident at the ionization front and find values of 1-3x 10(4) greater than the average interstellar field. From [FeII] line measurements, we conclude that the electron density in the ionized layer associated with the ionization front is of order 10(4) \\percc. Finally, our analysis of the helium and hydrogen recombination lines implies essential coincidence of the helium and hydrogen Stromgren spheres.

  8. Skyglow effects in UV and visible spectra: radiative fluxes.

    PubMed

    Kocifaj, Miroslav; Solano Lamphar, H A

    2013-09-30

    Several studies have tried to understand the mechanisms and effects of radiative transfer under different night-sky conditions. However, most of these studies are limited to the various effects of visible spectra. Nevertheless, the invisible parts of the electromagnetic spectrum can pose a more profound threat to nature. One visible threat is from what is popularly termed skyglow. Such skyglow is caused by injudiciously situated or designed artificial night lighting systems which degrade desired sky viewing. Therefore, since lamp emissions are not limited to visible electromagnetic spectra, it is necessary to consider the complete spectrum of such lamps in order to understand the physical behaviour of diffuse radiation at terrain level. In this paper, the downward diffuse radiative flux is computed in a two-stream approximation and obtained ultraviolet spectral radiative fluxes are inter-related with luminous fluxes. Such a method then permits an estimate of ultraviolet radiation if the traditionally measured illuminance on a horizontal plane is available. The utility of such a comparison of two spectral bands is shown, using the different lamp types employed in street lighting. The data demonstrate that it is insufficient to specify lamp type and its visible flux production independently of each other. Also the UV emissions have to be treated by modellers and environmental scientists because some light sources can be fairly important pollutants in the near ultraviolet. Such light sources can affect both the living organisms and ambient environment. PMID:23792881

  9. Calculation of Prompt Neutron Multiplicities and Spectra for Several Actinides

    SciTech Connect

    Hambsch, Franz-Josef; Oberstedt, Stephan; Tudora, Anabella; Vladuca, Gheorghita

    2005-05-24

    The prompt fission neutron multiplicity and spectra of actinides are nuclear data of crucial importance. Based on experimental fission yield and total kinetic energy data, new calculations for the prompt neutron multiplicity and spectra for 238U(n,f), 237Np(n,f) in the incident neutron energy range up to the second chance fission threshold, for 238U(n,f), up to 50 MeV, and for 252Cf(SF) have been performed.For the first time the multi-modality of the fission process was taken into account up to the second fission chance (about 6 MeV). Additionally, for some isotopes a more realistic fission fragment residual temperature distribution as well as an anisotropy of the prompt neutron emission led to improved agreement between the calculation and experimental results. Also, the range of fission fragment pairs entering in the multiplicity and spectrum model was extended over the entire experimental fission-fragment mass range. This led to an improved version of the Los Alamos (LA) model and especially to an improved determination of the input model parameters. In addition the LA model is extended towards higher incident neutron energy, where the fission of compound nuclei formed by charged particle emission occurs.

  10. Automatic classification of spectra from the Infrared Astronomical Satellite (IRAS)

    NASA Technical Reports Server (NTRS)

    Cheeseman, Peter; Stutz, John; Self, Matthew; Taylor, William; Goebel, John; Volk, Kevin; Walker, Helen

    1989-01-01

    A new classification of Infrared spectra collected by the Infrared Astronomical Satellite (IRAS) is presented. The spectral classes were discovered automatically by a program called Auto Class 2. This program is a method for discovering (inducing) classes from a data base, utilizing a Bayesian probability approach. These classes can be used to give insight into the patterns that occur in the particular domain, in this case, infrared astronomical spectroscopy. The classified spectra are the entire Low Resolution Spectra (LRS) Atlas of 5,425 sources. There are seventy-seven classes in this classification and these in turn were meta-classified to produce nine meta-classes. The classification is presented as spectral plots, IRAS color-color plots, galactic distribution plots and class commentaries. Cross-reference tables, listing the sources by IRAS name and by Auto Class class, are also given. These classes show some of the well known classes, such as the black-body class, and silicate emission classes, but many other classes were unsuspected, while others show important subtle differences within the well known classes.

  11. Transient ionization and solar flare X-ray spectra

    NASA Technical Reports Server (NTRS)

    Doschek, G. A.; Tanaka, K.

    1987-01-01

    In this paper the effects of a transiently ionizing solar flare plasma on the X-ray spectrum of iron between 1.85 and 1.92 A are considered. The atomic physics of the nonequilibrium spectrum is discussed, and reasons for differences in appearance from ionization equilibrium spectra are explained. The effect of spectral resolution on the ability to detect transient ionization in the iron X-ray spectrum is illustrated by synthetic spectra. A synthetic transiently ionizing spectrum is applied to the interpretation of spectra obtained from the SOX 1 spectrometer on the Japanese Hinotori spacecraft. Some indications of transient ionization are found, although counting statistics negate a strong conclusion. A hypothetical spectrometer with about one order of magnitude more sensitivity than the SOX 1 Hinotori or the bent crystal spectrometer flown on the Solar Maximum Mission (SMM) is also considered. The ranges of plasma parameters such as plasma emission measure and density that are necessary for transient ionization to be detected by such an instrument are discussed.

  12. Modeling of Neutron Spectra Based on Activation Analysis

    NASA Astrophysics Data System (ADS)

    Jovancevic, N.; Fridman, M.; Daraban, L.; Hambsch, F.-J.; Oberstedt, S.; Hult, M.; Lutter, G.; Marissens, G.; Stroh, H.

    Safe and economical use of nuclear energy and particularly the development of GEN-IV reactors impose a better understanding of prompt neutron emission in fission, as well as of the fission process as such. Therefore, accurate measurements of the prompt fission neutron spectra (PFNS) are very important. In this work, we are testing the possibility to determine the PFNS by an activation method called DONA (DOsimetry and Spectroscopy using Neuron Activation) recently developed at IRMM (Wieslander et al., 2010, Lövestam et al., 2009). This type of modeling of the neutron spectra, based on the activation analysis, can provide new information about an old problem which still exists today, i.e. the discrepancy between measured integral and differential data (Capote et al., 2012). The problem is that the calculated average cross section for a certain neutron reaction, by using the differential experimental PFNS, in many cases cannot reproduce satisfactorily the integral measured cross section values. The modeling of the neutron spectra by the DONA technique was tested with the standard neutron spectrum of the spontaneous fission of 252Cf. We analyzed the sensitivity of the unfolding procedure to the initial neutron energy spectrum, the influence of the neutron scattering, the possibility of using different activation reactions and we also made an estimation of the lowest measurable neutron fluence rate.

  13. Multivariate calibration applied to the quantitative analysis of infrared spectra

    SciTech Connect

    Haaland, D.M.

    1991-01-01

    Multivariate calibration methods are very useful for improving the precision, accuracy, and reliability of quantitative spectral analyses. Spectroscopists can more effectively use these sophisticated statistical tools if they have a qualitative understanding of the techniques involved. A qualitative picture of the factor analysis multivariate calibration methods of partial least squares (PLS) and principal component regression (PCR) is presented using infrared calibrations based upon spectra of phosphosilicate glass thin films on silicon wafers. Comparisons of the relative prediction abilities of four different multivariate calibration methods are given based on Monte Carlo simulations of spectral calibration and prediction data. The success of multivariate spectral calibrations is demonstrated for several quantitative infrared studies. The infrared absorption and emission spectra of thin-film dielectrics used in the manufacture of microelectronic devices demonstrate rapid, nondestructive at-line and in-situ analyses using PLS calibrations. Finally, the application of multivariate spectral calibrations to reagentless analysis of blood is presented. We have found that the determination of glucose in whole blood taken from diabetics can be precisely monitored from the PLS calibration of either mind- or near-infrared spectra of the blood. Progress toward the non-invasive determination of glucose levels in diabetics is an ultimate goal of this research. 13 refs., 4 figs.

  14. Multivariate calibration applied to the quantitative analysis of infrared spectra

    NASA Astrophysics Data System (ADS)

    Haaland, David M.

    1992-03-01

    Multivariate calibration methods are very useful for improving the precision, accuracy, and reliability of quantitative spectral analyses. Spectroscopists can more effectively use these sophisticated statistical tools if they have a qualitative understanding of the techniques involved. A qualitative picture of the factor analysis multivariate calibration methods of partial least squares (PLS) and principal component regression (PCR) is presented using infrared calibrations based upon spectra of phosphosilicate glass thin films on silicon wafers. Comparisons of the relative prediction abilities of four different multivariate calibration methods are given based on Monte Carlo simulations of spectral calibration and prediction data. The success of multivariate spectral calibrations is demonstrated for several quantitative infrared studies. The infrared absorption and emission spectra of thin-film dielectrics used in the manufacture of microelectronic devices demonstrate rapid, nondestructive at-line and in- situ analyses using PLS calibrations. Finally, the application of multivariate spectral calibrations to reagentless analysis of blood is presented. We have found that the determination of glucose in whole blood taken from diabetics can be precisely monitored from the PLS calibration of either mid- or near-infrared spectra of the blood. Progress toward the noninvasive determination of glucose levels in diabetics is an ultimate goal of this research.

  15. Utilizing Thermal Infrared Spectra of Mars for Mission Planning

    NASA Astrophysics Data System (ADS)

    Kirkland, L. E.; Forney, P. B.; Herr, K. C.; Keim, E. R.

    2000-07-01

    Reflectance and emission spectroscopy remain the most capable method for mineral identification from orbit. However, to best utilize spectra returned from Mars for mission planning, the current level of understanding of the spectral signature of weathered and rough materials should be considered. Materials measured in the laboratory tend to have band strengths that are stronger than those measured in the field. This difference results mainly from surface roughness, weathering effects, and the presence of a mixture of different materials in the field of view (mixed pixel effect). Thus it is critical to extend spectral measurements from the laboratory into the field in order to understand the spectral behavior of real-world materials. This is best done by utilizing a combination of airborne, field, and laboratory spectra of terrestrial materials, and then applying the lessons learned to spectra recorded of Mars. The ability of any spectral instrument to detect and identify minerals depends on a combination of (1) the mineral's band strength; (2) band width; (3) the instrument's spectral resolution; (4) signal-to-noise ratio (SNR); and (5) atmospheric interference. These points are not always considered in quotes of the detection limits for a given instrument and material. Here we discuss these effects, and explain their relevance for assessing the order in which spectral instruments should be flown to best implement a phased approach to "follow the water," and for landing site selection and sample return.

  16. Observation of ultralow-level Al impurities on a silicon surface by high-resolution grazing emission x-ray fluorescence excited by synchrotron radiation

    SciTech Connect

    Kubala-Kukus, A.; Banas, D.; Pajek, M.; Cao, W.; Dousse, J.-Cl.; Hoszowska, J.; Kayser, Y.; Szlachetko, M.; Salome, M.; Susini, J.; Szlachetko, J.

    2009-09-15

    We demonstrate that ultralow-level Al impurities on a silicon surface can be measured by using the high-resolution grazing emission x-ray fluorescence (GEXRF) technique combined with synchrotron-radiation excitation. An Al-impurity level of about 10{sup 12} atoms/cm{sup 2} was reached by observing the Al K{alpha} x-ray fluorescence in the resonant Raman-scattering background-''free'' regime by choosing an appropriate beam energy below the Si K absorption edge. Present results show that by combining the GEXRF method with the vapor phase decomposition technique the 10{sup 7} atoms/cm{sup 2} level can be reached for Al detection on silicon. Finally, we found that the high-resolution GEXRF technique is a sensitive tool to study the morphology of surface nanostructures.

  17. Direct observation of phonon emission from hot electrons: spectral features in diamond secondary electron emission.

    PubMed

    O'Donnell, Kane M; Edmonds, Mark T; Ristein, Jürgen; Rietwyk, Kevin J; Tadich, Anton; Thomsen, Lars; Pakes, Christopher I; Ley, Lothar

    2014-10-01

    In this work we use high-resolution synchrotron-based photoelectron spectroscopy to investigate the low kinetic energy electron emission from two negative electron affinity surfaces of diamond, namely hydrogenated and lithiated diamond. For hydrogen-terminated diamond electron emission below the conduction band minimum (CBM) is clearly observed as a result of phonon emission subsequent to carrier thermalization at the CBM. In the case of lithiated diamond, we find the normal conduction band minimum emission peak is asymmetrically broadened to higher kinetic energies and argue the broadening is a result of ballistic emission from carriers thermalized to the CBM in the bulk well before the onset of band-bending. In both cases the spectra display intensity modulations that are the signature of optical phonon emission as the main mechanism for carrier relaxation. To our knowledge, these measurements represent the first direct observation of hot carrier energy loss via photoemission. PMID:25192212

  18. Data collapse of the spectra of water-based stable single-bubble sonoluminescence

    NASA Astrophysics Data System (ADS)

    Levinsen, Mogens T.

    2010-09-01

    In the early days of stable single-bubble sonoluminescence, it was strongly debated whether the emission was blackbody radiation or whether the bubble was transparent to its own radiation (volume emission). Presently, the volume emission picture is nearly universally accepted. We present new measurements of spectra with apparent color temperatures ranging from 6000 to 21 000 K. We show through data collapse that within experimental uncertainty, apart from a constant, the spectra of strongly driven stable single-bubble sonoluminescence in water can be written as the product between a universal function of wavelength and a functional form that only depends on wavelength and apparent temperature but has no reference to any other parameter specific to the experimental situation. This remarkable result does question our theoretical understanding of the state of the plasma in the interior of strongly driven stable sonoluminescent bubbles.

  19. ELEMENTAL ABUNDANCES IN THE EJECTA OF OLD CLASSICAL NOVAE FROM LATE-EPOCH SPITZER SPECTRA

    SciTech Connect

    Helton, L. Andrew; Vacca, William D.; Gehrz, Robert D.; Woodward, Charles E.; Shenoy, Dinesh P.; Wagner, R. Mark; Evans, Aneurin; Krautter, Joachim; Schwarz, Greg J.; Starrfield, Sumner

    2012-08-10

    We present Spitzer Space Telescope mid-infrared IRS spectra, supplemented by ground-based optical observations, of the classical novae V1974 Cyg, V382 Vel, and V1494 Aql more than 11, 8, and 4 years after outburst, respectively. The spectra are dominated by forbidden emission from neon and oxygen, though in some cases, there are weak signatures of magnesium, sulfur, and argon. We investigate the geometry and distribution of the late time ejecta by examination of the emission line profiles. Using nebular analysis in the low-density regime, we estimate lower limits on the abundances in these novae. In V1974 Cyg and V382 Vel, our observations confirm the abundance estimates presented by other authors and support the claims that these eruptions occurred on ONe white dwarfs (WDs). We report the first detection of neon emission in V1494 Aql and show that the system most likely contains a CO WD.

  20. Infrared spectra of natural and synthetic malachites

    NASA Astrophysics Data System (ADS)

    Schuiskii, A. V.; Zorina, M. L.

    2013-09-01

    IR absorption and reflection spectra of dark and light samples of natural and synthetic malachite over 400-4000 cm-1 are studied for the purpose of improving the synthesis technique and in order to distinguish between natural malachite and malachite grown from ammonia solutions. Nitrogen was not detected in the IR spectra or in microprobe analyses of the synthetic material. The differences found in the IR spectra were insignificant and cannot be regarded as distinctive indicators of these materials.