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Sample records for balmer spectra

  1. Synthetic Spectra of H Balmer and HE I Absorption Lines. I. Stellar Library

    NASA Astrophysics Data System (ADS)

    González Delgado, Rosa M.; Leitherer, Claus

    1999-12-01

    We present a grid of synthetic profiles of stellar H Balmer and He I lines at optical wavelengths with a sampling of 0.3 Å. The grid spans a range of effective temperature 50,000 K>=Teff>=4000 K, and gravity 0.0<=logg<=5.0 at solar metallicity. For Teff>=25,000 K, non-LTE stellar atmosphere models are computed using the code TLUSTY (Hubeny). For cooler stars, Kurucz LTE models are used to compute the synthetic spectra. The grid includes the profiles of the high-order hydrogen Balmer series and He I lines for effective temperatures and gravities that have not been previously synthesized. The behavior of H8 to H13 and He I λ3819 with effective temperature and gravity is very similar to that of the lower terms of the series (e.g., Hβ) and the other He I lines at longer wavelengths; therefore, they are suited for the determination of the atmospheric parameters of stars. These lines are potentially important to make predictions for these stellar absorption features in galaxies with active star formation. Evolutionary synthesis models of these lines for starburst and poststarburst galaxies are presented in a companion paper. The full set of the synthetic stellar spectra is available for retrieval at our website or on request from the authors.

  2. Rapid variations of balmer line strengths in the spectra of Be stars. Ph.D. Thesis; [photoelectric spectrophotometric measurements

    NASA Technical Reports Server (NTRS)

    Mcbeath, K. B.

    1974-01-01

    Low resolution photoelectric spectrophotometric measurements of the first four members of the Balmer series in the spectra of one Be and five Be (shell) stars were obtained with the 92-cm telescope and image dissecting scanner. Equivalent widths were computed for each observation, and their standard deviations from the mean values were examined. Results indicate that in three of the program stars, at least one of the Balmer lines shows significant fluctuations in equivalent width. These fluctuations amount to a few per cent of total line strength and the time scales appear to be on the order of three to thirty minutes. The fluctuations are not always present in a given star, indicating that the mechanism producing them may not be continuous. The noncontinuous and nonperiodic nature of the variations, along with their short time scale suggest some form of flare-like or shock origin for the phenomenon.

  3. Segunda discontinuidad de Balmer y procesos físicos en envolturas extendidas de estrellas Be

    NASA Astrophysics Data System (ADS)

    Bibbo, I.; Cruzado, A.; Ringuelet, A.

    We study a group of Be stars in which the second Balmer jump is observed. Our aim is to correlate the second Balmer jump with other spectral features. Spectroscopic observations were performed with the 2.15 m telescope at Complejo Astronómico el Leoncito, CASLEO (San Juan, Argentina). In December 2001 and August 2002 high resolution echelle spectra were obtained with a REOSC echelle spectrograph. We find that, when a second Balmer jump in emission is observed, an emission in λ = 4233,17 Å of FeII multiplet 27 is also, generally seen. Besides, the electron temperature of the region of the envelope where the second jump is formed is estimated assuming that radiative recombinations cause the flux emission in the Balmer continuum. The temperature values obtained in this way are found correlated with the measure of the second Balmer jump.

  4. Balmer line shifts in quasars

    NASA Astrophysics Data System (ADS)

    Sulentic, J. W.; Marziani, P.; Del Olmo, A.; Zamfir, S.

    2016-02-01

    We offer a broad review of Balmer line phenomenology in type 1 active galactic nuclei, briefly summarising luminosity and radio loudness effects, and discussing interpretation in terms of nebular physics along the 4D eigenvector 1 sequence of quasars. We stress that relatively rare, peculiar Balmer line profiles (i.e., with large shifts with respect to the rest frame or double and multiple peaked) that start attracted attentions since the 1970s are still passable of multiple dynamical interpretation. More mainstream objects are still not fully understood as well, since competing dynamical models and geometries are possible. Further progress may come from inter-line comparison across the 4D Eigenvector 1 sequence.

  5. Variability of Balmer Profiles in Magnetic Ap/Bp Stars

    NASA Astrophysics Data System (ADS)

    Valyavin, G.; Lee, B.-C.; Shulyak, D.; Han, I.; Kochukhov, O.; Khang, D.-I.; Kim, K.-M.

    2007-06-01

    A set of high precision measurements of weak variations of hydrogen lines in spectra of seven magnetic Ap/Bp stars was carried out using the BOES echelle spectrograph of the Bohuynsan Optical Astronomy Observatory (South Korea). A weak (1-2 %) periodic variability of the Balmer line wings has been detected in the spectra of 2 program stars. Upper limits of possible variations are presented for the remaining 5 objects. We discuss the discovered variability in the framework of model atmospheres with magnetic force terms included. The periodic changes in the Balmer profiles are caused by perturbations in atmospheres of Ap/Bp stars due to their rotationally modulated non-force-free magnetic fields.

  6. Anomalous Balmer continuum temperatures in the Orion Nebula

    NASA Technical Reports Server (NTRS)

    Walter, Donald L.; Dufour, Reginald J.

    1994-01-01

    New long-slit spectra of the Orion Nebula in the near-ultraviolet were used to calculate the Balmer recombination temperature, T(Bac), from the Balmer discontinuity at 3646 A. The spatially resolved data show a decrease in temperature moving to the west of Theta(sup 1) Ori C, from 8400 K at a distance of 40 sec to a low of 2800 K at a distance of 220 sec. Such values are much lower than previously reported. The effect of scattered starlight on these results is calculated and shown to be less than 10%. Previous studies which found scattered light to be important at the discontinuity are in error. Such low temperatures and their impact on nebular physics and abundances are disconcerting and require further study.

  7. Self-broadening of the hydrogen Balmer α line

    NASA Astrophysics Data System (ADS)

    Allard, N. F.; Kielkopf, J. F.; Cayrel, R.; van't Veer-Menneret, C.

    2008-03-01

    Context: Profiles of hydrogen lines in stellar spectra are determined by the properties of the hydrogen atom and the structure of the star's atmosphere. Hydrogen line profiles are therefore a very important diagnostic tool in stellar modeling. In particular they are widely used as effective temperature criterion for stellar atmospheres in the range T_eff 5500-7000 K. Aims: In cool stars such as the Sun hydrogen is largely neutral and the electron density is low. The line center width at half maximum and the spectral energy distribution in the wings are determined primarily by collisions with hydrogen atoms due to their high relative density. This work aims to provide benchmark calculations of Balmer α based on recent H2 potentials. Methods: For the first time an accurate determination of the broadening of Balmer α by atomic hydrogen is made in a unified theory of collisional line profiles using ab initio calculations of molecular hydrogen potential energies and transition matrix elements among singlet and triplet electronic states. Results: We computed the shape, width and shift of the Balmer α line perturbed by neutral hydrogen and studied their dependence on temperature. We present results over the full range of temperatures from 3000 to 12 000 K needed for stellar spectra models. Conclusions: Our calculations lead to larger values than those obtained with the commonly used Ali & Griem (1966, Phys. Rev. A, 144, 366) theory and are closer to the recent calculations of Barklem et al. (2000a, A&A, 355, L5; 2000b, A&A, 363, 1091). We conclude that the line parameters are dependent on the sum of many contributing molecular transitions, each with a different temperature dependence, and we provide tables for Balmer α. The unified line shape theory with complete molecular potentials also predicts additional opacity in the far non-Lorentzian wing.

  8. Six Balmer-dominated supernova remnants

    SciTech Connect

    Smith, R.C.; Kirshner, R.P.; Blair, W.P.; Winkler, P.F. Johns Hopkins University, Baltimore, MD Middlebury College, VT )

    1991-07-01

    Spectra of six Balmer-dominated SNRs are examined: the Galactic SNR of SN 1572 and SN 1006, the LMC SNR 0505-67.9, 0509-67.5, 0519-69.0, and 0548-70.4. A shock velocity is derived for each SNR with broad H-alpha and a possible lower limit of the shock velocity in 0509-67.5. Models are used which show that the use of the ratio of broad to narrow intensity as an indicator of shock velocity is not reliable. The observed intensity ratios do not correspond to either the commonly assumed case of no equilibration or to the other extreme of total equilibration. Distances to the filaments in SN 1572 and SN 1006 of 1.5-3.1 kpc and 1.4-2.8 kpc, respectively, are obtained. The ages are estimated to range from about 10,000 yr for 0505-67.9 and 0548-70.4 to less than 1500 yr for the small SNR 0509-67.5 and 0519-69.0.l. These two young SNR bring the number of SNe in the LMC to at least five in the past 1500 yr, making the SN rate per unit luminosity comparable to that reported for late spiral galaxies. 40 refs.

  9. Balmer's Manuscripts and the Construction of His Series

    ERIC Educational Resources Information Center

    Banet, Leo

    1970-01-01

    Presents the results of an analysis of Balmer's draft manuscripts, which revealed new and pertinent details about the genesis of the Balmer series. In particular the origin and nature of Balmer's geometrical construction for the series is described. In addition, it is shown that the Balmer series played a direct role in the formulation of the…

  10. Balmer-α spectrum measurements of the LHD one-third ion source

    NASA Astrophysics Data System (ADS)

    Wada, M.; Kenmotsu, T.; Kisaki, M.; Nakano, H.; Nishiura, M.; Tsumori, K.

    2016-02-01

    Wavelength spectra of Balmer-α light from plasmas in the extraction region of the Large Helical Device-R&D negative ion source, or the LHD one-third ion source have exhibited a blue shift as a negative bias voltage was applied to the plasma grid. The blue shift increased as the negative bias voltage with respect to the local plasma potential was increased. The measured spectra were compared with the velocity distributions of surface reflected hydrogen atoms calculated by atomic collisions in amorphous target code. The arc power and the source H2 pressure also affected the shift and broadening in the observed Balmerspectra. The possibility of identifying the negative hydrogen ions produced at the low work function plasma grid surface by high resolution spectroscopy is discussed.

  11. Balmer-α spectrum measurements of the LHD one-third ion source.

    PubMed

    Wada, M; Kenmotsu, T; Kisaki, M; Nakano, H; Nishiura, M; Tsumori, K

    2016-02-01

    Wavelength spectra of Balmer-α light from plasmas in the extraction region of the Large Helical Device-R&D negative ion source, or the LHD one-third ion source have exhibited a blue shift as a negative bias voltage was applied to the plasma grid. The blue shift increased as the negative bias voltage with respect to the local plasma potential was increased. The measured spectra were compared with the velocity distributions of surface reflected hydrogen atoms calculated by atomic collisions in amorphous target code. The arc power and the source H2 pressure also affected the shift and broadening in the observed Balmerspectra. The possibility of identifying the negative hydrogen ions produced at the low work function plasma grid surface by high resolution spectroscopy is discussed. PMID:26931989

  12. Balmer decrements of T Tau stars

    NASA Astrophysics Data System (ADS)

    Katysheva, N. A.

    1981-04-01

    The relative intensities of Balmer lines calculated on the basis of Sobolev's probability method (1947) and the observed decrements of T Tau stars in the catalog of Cohen and Kuhi (1979) are compared with spectral classes between K5 and M5. For the group of stars, G5-K5, studied by Grinin (1980), emission was found to be predominantly of an envelope type, with less of a part played by chromospheric radiation. In K5-M5 stars, however, the envelope makes a smaller contribution to the total radiation, and most of the emission arises in the dense gas at the surface of the star. A comparison of the Balmer decrements of T Tau stars of different spectral classes and flare stars shows that in a transition to stars of lower luminosity, the role of chromospheric radiation increases.

  13. Flare model sensitivity of the Balmer spectrum

    NASA Technical Reports Server (NTRS)

    Falchi, A.; Falciani, R.; Smaldone, L. A.; Tozzi, G. P.

    1989-01-01

    Careful studies of various chromospheric spectral signatures are very important in order to explore their possible sensitivity to the modifications of the thermodynamic quantities produced by the flare occurrence. Pioneer work of Canfield and co-workers have shown how the H alpha behavior is able to indicate different changes in the atmospheric parameters structure associated to the flare event. It was decided to study the behavior of the highest Balmer lines and of the Balmer continuum in different solar flare model atmospheres. These spectral features, originating in the deep photosphere in a quiet area, may have a sensitivity different from H alpha to the modification of a flare atmosphere. The details of the method used to compute the Stark profile of the higher Balmer line (n is greater than or equal to 6) and their merging were extensively given elsewhere (Donati-Falchi et al., 1985; Falchi et al., 1989). The models used were developed by Ricchiazzi in his thesis (1982) evaluating the chromospheric response to both the nonthermal electron flux, for energy greater than 20 kev, (F sub 20) and to the thermal conduction, (F sub c). The effect of the coronal pressure values (P sub O) at the apex of the flare loop is also included.

  14. Formation of broad Balmer wings in symbiotic stars

    NASA Astrophysics Data System (ADS)

    Chang, Seok-Jun; Heo, Jeong-Eun; Hong, Chae-Lin; Lee, Hee-Won

    2016-07-01

    Symbiotic stars are binary systems composed of a hot white dwarf and a mass losing giant. In addition to many prominent emission lines symbiotic stars exhibit Raman scattered O VI features at 6825 and 7088 Å. Another notable feature present in the spectra of many symbiotics is the broad wings around Balmer lines. Astrophysical mechanisms that can produce broad wings include Thomson scattering by free electrons and Raman scattering of Ly,β and higher series by neutral hydrogen. In this poster presentation we produce broad wings around Hα and H,β adopting a Monte Carlo techinique in order to make a quantitative comparison of these two mechanisms. Thomson wings are characterized by the exponential cutoff given by the termal width whereas the Raman wings are dependent on the column density and continuum shape in the far UV region. A brief discussion is provided.

  15. Variations of the ultraviolet Fe II and Balmer continuum emission in the Seyfert galaxy NGC 5548

    NASA Technical Reports Server (NTRS)

    Maoz, D.; Netzer, H.; Peterson, B. M.; Bechtold, J.; Bertram, R.; Bochkarev, N. G.; Carone, T. E.; Dietrich, M.; Filippenko, A. V.; Kollatschny, W.

    1993-01-01

    We present measurements of the Balmer continuum/Fe II emission blend between 2160 and 4130 A in the Seyfert galaxy NGC 5548. The measurements are from spectra obtained as part of the combined space-based and ground-based monitoring program of this object in 1988-1989. An iterative scheme is used to determine and subtract the continuum emission underlying the emission blend so as to obtain a light curve sampled once every four days. The small blue bump is an important component of the emission-line cooling, constituting about one third of the line flux in this object. Its flux varies with an amplitude of approximately +/- 20 percent about the mean, similar to the amplitude of the Balmer line variations during the same period. Its light curve resembles that of Ly-alpha, with a lag of about 10 days behind the continuum variations. The bump variation amplitude is independent of the wavelength interval where it is measured, which indicates that both the Balmer continuum and Fe II emission have comparable variation amplitudes. These results suggest that the Fe II UV multiplets and the Balmer continuum are emitted in the same parts of the broad-line region as most other broad emission lines in this object.

  16. Recombination and collisionally excited Balmer lines

    NASA Astrophysics Data System (ADS)

    Raga, A. C.; Castellanos-Ramírez, A.; Esquivel, A.; Rodríguez-González, A.; Velázquez, P. F.

    2015-10-01

    We present a model for the statistical equilibrium of the levels of H, considering recombinations to excited levels, collisional excitations up from the ground state and spontaneous radiative transitions. This problem has a simple "cascade matrix" solution, describing a cascade of downwards spontaneous transitions fed by both recombinations and collisional excitations. The resulting predicted Balmer line ratios show a transition between a low temperature and a high temperature regime (dominated by recombinations and by collisional excitations, respectively), both with only a weak line ratio vs. temperature dependence. This clear characteristic allows a direct observational identification of regions in which the Balmer lines are either recombination or collisionally excited transitions. We find that for a gas in coronal ionization equilibrium the Halpha and Hbeta lines are collisionally excited for all temperatures. In order to have recombination Halpha and Hbeta it is necessary to have higher ionization fractions of H than the ones obtained from coronal equilibrium (e.g., such as the ones found in a photoionized gas).

  17. On Production Mechanisms For Balmer Line Radiation From 'Cold' Atomic Hydrogen and Deuterium In Fusion Edge Plasmas

    SciTech Connect

    Hey, John Douglas

    2010-10-29

    Published arguments, which assign dominant roles to atomic metastability and molecular ion dissociation in the production of 'narrow' Zeeman component Balmer line radiation from the tokamak edge plasma, have been examined critically in relation to: l-redistribution by proton collisions, molecular ion-proton equipartition, and ion acceleration by the plasma sheath (scrape-off layer) potential. These processes are found to constrain the contributions from metastable atoms and from dissociative excitation of molecular ions to 'narrow' Balmer spectra emitted from the plasma edge, in relation to the corresponding contributions from electron impact-induced dissociative excitation of neutral molecules.

  18. Laser-induced plasma spectroscopy of hydrogen Balmer series in laboratory air.

    PubMed

    Swafford, Lauren D; Parigger, Christian G

    2014-01-01

    Stark-broadened emission profiles for the hydrogen alpha and beta Balmer series lines in plasma are measured to characterize electron density and temperature. Plasma is generated using a typical laser-induced breakdown spectroscopy (LIBS) arrangement that employs a focused Q-switched neodymium-doped yttrium aluminum garnet (Nd : YAG) laser, operating at the fundamental wavelength of 1064 nm. The temporal evolution of the hydrogen Balmer series lines is explored using LIBS. Spectra from the plasma are measured following laser-induced optical breakdown in laboratory air. The electron density is primarily inferred from the Stark-broadened experimental data collected at various time delays. Due to the presence of nitrogen and oxygen in air, the hydrogen alpha and beta lines become clearly discernible from background radiation for time delays of 0.4 and 1.4 μs, respectively. PMID:25226255

  19. Variations of the high-level Balmer line spectrum of the helium-strong star σ Orionis E

    NASA Astrophysics Data System (ADS)

    Smith, M. A.; Bohlender, D. A.

    2007-12-01

    Using the high-level Balmer lines and continuum, we trace the density structure of two magnetospheric disk segments of the prototypical Bp star σ Orionis E (B2p) as these segments occult portions of the star during the rotational cycle. High-resolution spectra of the Balmer lines ≥H9 and Balmer edge were obtained on seven nights in January-February 2007 at an average sampling of 0.01 cycles. We measured equivalent width variations due to the star occultations by two disk segments 0.4 cycles apart and constructed differential spectra of the migrations of the corresponding absorptions across the Balmer line profiles. We first estimated the rotational and magnetic obliquity angles. We then simulated the observed Balmer jump variation using the model atmosphere codes synspec/circus and evaluated the disk geometry and gas thermodynamics. We find that the two occultations are caused by two disk segments. The first of these transits quickly, indicating that the segment resides in a range of distances, perhaps 2.5-6 R*, from the star. The second consists of a more slowly moving segment situated closer to the surface and causing two semi-resolved absorbing maxima. During its transit this segment brushes across the star's “lower” limb. Judging from the line visibility up to H23-H24 during the occultations, both disk segments have mean densities near 1012 cm-3 and are opaque in the lines and continuum. They have semiheights less than 1/2 R*, and their temperatures are near 10 500 K and 12 000 K, respectively. In all, the disks of Bp stars have a much more complicated geometry than has been anticipated, as evidenced by their (sometimes) non-coplanarity, de-centerness, and from star to star, differences in disk height. Based on observations obtained at the the Dominion Astrophysical Observatory, Herzberg Institute of Astrophysics, National Research Council of Canada.

  20. Variation in the Pre-transit Balmer Line Signal Around the Hot Jupiter HD 189733b

    NASA Astrophysics Data System (ADS)

    Cauley, P. Wilson; Redfield, Seth; Jensen, Adam G.; Barman, Travis

    2016-07-01

    As followup to our recent detection of a pre-transit signal around HD 189733 b, we obtained full pre-transit phase coverage of a single planetary transit. The pre-transit signal is again detected in the Balmer lines but with variable strength and timing, suggesting that the bow shock geometry reported in our previous work does not describe the signal from the latest transit. We also demonstrate the use of the Ca ii H and K residual core flux as a proxy for the stellar activity level throughout the transit. A moderate trend is found between the pre-transit absorption signal in the 2013 data and the Ca ii H flux. This suggests that some of the 2013 pre-transit hydrogen absorption can be attributed to varying stellar activity levels. A very weak correlation is found between the Ca ii H core flux and the Balmer line absorption in the 2015 transit, hinting at a smaller contribution from stellar activity compared to the 2013 transit. We simulate how varying stellar activity levels can produce changes in the Balmer line transmission spectra. These simulations show that the strength of the 2013 and 2015 pre-transit signals can be reproduced by stellar variability. If the pre-transit signature is attributed to circumplanetary material, its evolution in time can be described by accretion clumps spiraling toward the star, although this interpretation has serious limitations. Further high-cadence monitoring at Hα is necessary to distinguish between true absorption by transiting material and short-term variations in the stellar activity level.

  1. Discovery of an activity cycle in the solar analog HD 45184. Exploring Balmer and metallic lines as activity proxy candidates

    NASA Astrophysics Data System (ADS)

    Flores, M.; González, J. F.; Jaque Arancibia, M.; Buccino, A.; Saffe, C.

    2016-05-01

    Context. Most stellar activity cycles similar to that found in the Sun have been detected by using the chromospheric Ca ii H&K lines as stellar activity proxies. However, it is unclear whether such activity cycles can be identified using other optical lines. Aims: We aim to detect activity cycles in solar-analog stars and determine whether they can be identified through other optical lines, such as Fe II and Balmer lines. We study the solar-analog star HD 45184 using HARPS spectra. The temporal coverage and high quality of the spectra allow us to detect both long- and short-term activity variations. Methods: We analysed the activity signatures of HD 45184 by using 291 HARPS spectra obtained between 2003 and 2014. To search for line-core flux variations, we focused on Ca ii H&K and Balmer Hα and Hβ lines, which are typically used as optical chromospheric activity indicators. We calculated the HARPS-S index from Ca ii H&K lines and converted it into the Mount Wilson scale. In addition, we also considered the equivalent widths of Balmer lines as activity indicators. Moreover, we analysed the possible variability of Fe ii and other metallic lines in the optical spectra. The spectral variations were analysed for periodicity using the Lomb-Scargle periodogram. Results: We report for the first time a long-term 5.14-yr activity cycle in the solar-analog star HD 45184 derived from Mount Wilson S index. This makes HD 45184 one of most similar stars to the Sun with a known activity cycle. The variation is also evident in the first lines of the Balmer series, which do not always show a correlation with activity in solar-type stars. Notably, unlike the solar case, we also found that the equivalent widths of the high photospheric Fe ii lines (4924 Å, 5018 Å and 5169 Å) are modulated (±2 mÅ) by the chromospheric cycle of the star. These metallic lines show variations above 4σ in the rms spectrum, while some Ba ii and Ti ii lines present variations at 3σ level, which

  2. Theoretical quasar emission-line ratios. V - Balmer continuum emission

    NASA Technical Reports Server (NTRS)

    Puetter, R. C.; Levan, P. D.

    1982-01-01

    Isothermal, isobaric models of quasar emission line regions are presented which include an improved treatment of radiative transfer in the bound-free continua, based on a generalization of frequency-integrated line transfer techniques and on the use of a probabilistic radiative transfer equation which explicitly distinguishes between the flux divergence coefficient and the photon escape probability. It is found that Balmer continuum emission can be obtained without compromising observed line ratios. It is also established that optically thin or thick Balmer continuum emission models with blended Fe II line are consistent with 4000-2000 A 'blue bump' observations, and that the improved radiative transfer treatment makes order-of-magnitude corrections to level populations and local cooling rates calculated with past techniques.

  3. Atmosphere Explorer observations of the geocoronal H Balmer alpha nightglow

    NASA Technical Reports Server (NTRS)

    Burrage, M. D.; Yee, J. H.; Abreu, V. J.

    1989-01-01

    The Balmer alpha nightglow emission of geocoronal atomic hydrogen has been investigated using photometric data obtained by the Visible Airglow Experiment on board the Atmosphere Explorer E satellite. The measured H Balmer alpha intensities are presented as a function of solar depression angle, observation zenith angle, and azimuth relative to the sun for solar minimum conditions. The results are at variance with the earlier D2A satellite observations but in better agreement with previous ground-based studies. As a result of comparison with theoretical predictions, the present observations reaffirm the findings of the ground-based investigations in implying that values for the Lyman beta line center flux are a factor of 2 greater than those derived from direct measurements.

  4. Laser plasma diagnostics and self-absorption measurements of the Hβ Balmer series line

    NASA Astrophysics Data System (ADS)

    Gautam, Ghaneshwar; Parigger, Christian G.; Surmick, David M.; EL Sherbini, Ashraf M.

    2016-02-01

    In this work, the peak-separation of the Balmer series hydrogen beta line was measured to determine the electron density of laser-induced plasma from spatially and temporally resolved spectra collected in laboratory air at standard ambient temperature and pressure. The self-absorption phenomenon is investigated by using a mirror that retro-reflects the emitted radiation through the plasma. The experimental data with and without the mirror were analyzed with available hydrogen beta computer simulations. Hardly any self-absorption was found as indicated by the correction factors that only marginally differ from unity. The obtained electron density values are also compared with the electron densities from nearby nitrogen lines. The hydrogen beta Hβ peak-separation method yields reliable results for an electron density of the order of 1 ×1017cm-3 for time delays of 5 μs from plasma generation, which confirms that self-absorption is insignificant for such electron densities.

  5. Testing convection theories using Balmer line profiles of A, F, and G stars

    NASA Astrophysics Data System (ADS)

    Gardiner, R. B.; Kupka, F.; Smalley, B.

    1999-07-01

    We consider the effects of convection on the Balmer line profiles ({H_α} and {H_β}) of A, F, and G stars. The standard mixing-length theory (MLT) atlas9 models of Kurucz (1993), with and without overshooting, are compared to atlas9 models based on the turbulent convection theory proposed by Canuto & Mazzitelli (1991, 1992) and implemented by Kupka (1996), and the improved version of this model proposed by Canuto et al. (1996) also implemented by Kupka. The Balmer line profiles are a useful tool in investigating convection because they are very sensitive to the parameters of convection used in the stellar atmosphere codes. The {H_α} and {H_β} lines are formed at different depths in the atmosphere. The {H_α} line is formed just above the convection zone. The {H_β} line, however, is partially formed inside the convection zone. We have calculated the {T_eff} of observed stars by fitting Balmer line profiles to synthetic spectra and compared this to: (i) the {T_eff} of the fundamental stars; (ii) the {T_eff} of stars determined by the Infra-Red Flux Method and (iii) the {T_eff} determined by Geneva photometry for the stars in the Hyades cluster. We find that the results from the {H_α} and {H_β} lines are different, as expected, due to the differing levels of formation. The tests are inconclusive between three of the four models; MLT with no overshooting, CM and CGM models, which all give results in reasonable agreement with fundamental values. The results indicate that for the MLT theory with no overshooting it is necessary to set the mixing length parameter alpha equal to 0.5 for stars with {T_eff <= 6000} K or {T_eff >= 7000} K. However for stars with {6000} K{<= T_eff <= 7000} K the required value for the parameter is {alpha >= 1.25}. Models with overshooting are found to be clearly discrepant, consistent with the results with uvby photometry by Smalley & Kupka (1997). Based on observations made at the Observatorio del Roque de los Muchachos using the

  6. Collisionless Shocks in a Partially Ionized Medium. II. Balmer Emission

    NASA Astrophysics Data System (ADS)

    Morlino, G.; Bandiera, R.; Blasi, P.; Amato, E.

    2012-12-01

    Strong shocks propagating into a partially ionized medium are often associated with optical Balmer lines. This emission is due to impact excitation of neutral hydrogen by hot protons and electrons in the shocked gas. The structure of such Balmer-dominated shocks has been computed in a previous paper, where the distribution function of neutral particles was derived from the appropriate Boltzmann equation including coupling with ions and electrons through charge exchange and ionization. This calculation showed how the presence of neutrals can significantly modify the shock structure through the formation of a neutral-induced precursor ahead of the shock. Here we follow up on our previous work and investigate the properties of the resulting Balmer emission, with the aim of using the observed radiation as a diagnostic tool for shock parameters. Our main focus is on supernova remnant shocks, and we find that, for typical parameters, the Hα emission typically has a three-component spectral profile, where (1) a narrow component originates from upstream cold hydrogen atoms, (2) a broad component comes from hydrogen atoms that have undergone charge exchange with shocked protons downstream of the shock, and (3) an intermediate component is due to hydrogen atoms that have undergone charge exchange with warm protons in the neutral-induced precursor. The relative importance of these three components depends on the shock velocity, on the original degree of ionization, and on the electron-ion temperature equilibration level. The intermediate component, which is the main signature of the presence of a neutral-induced precursor, becomes negligible for shock velocities <~ 1500 km s-1. The width of the intermediate line reflects the temperature in the precursor, while the width of the narrow one is left unaltered by the precursor. In addition, we show that the profiles of both the intermediate and broad components generally depart from a thermal distribution, as a consequence of the

  7. Broad Balmer Absorption Line Variability: Evidence of Gas Transverse Motion in the QSO SDSS J125942.80+121312.6

    NASA Astrophysics Data System (ADS)

    Shi, Xiheng; Zhou, Hongyan; Shu, Xinwen; Zhang, Shaohua; Ji, Tuo; Pan, Xiang; Sun, Luming; Zhao, Wen; Hao, Lei

    2016-03-01

    We report on the discovery of broad Balmer absorption lines variability in the QSO SDSS J125942.80+121312.6, based on the optical and near-infrared spectra taken from the SDSS-I, SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS), and TripleSpec observations over a timescale of 5.8 years in the QSO's rest-frame. The blueshifted absorption profile of Hβ shows a variation of more than 5σ at a high velocity portion (\\gt 3000 {km} {{{s}}}-1) of the trough. We perform a detailed analysis for the physical conditions of the absorber using Balmer lines as well as metastable He i and optical Fe ii absorptions (λ4233 from b4P5/2 level and λ5169 from a6S5/2) at the same velocity. These Fe ii lines are identified in the QSO spectra for the first time. According to the photoionization simulations, we estimate a gas density of n({{H}})≈ {10}9.1 {{cm}}-3 and a column density of {N}{col}({{H}})≈ {10}23 {{cm}}-2 for the BOSS data, but the model fails to predict the variations of ionic column densities between the SDSS and BOSS observations if changes in ionizing flux are assumed. We thus propose transverse motion of the absorbing gas being the cause of the observed broad Balmer absorption line variability. In fact, we find that the changes in covering factors of the absorber can well-reproduce all of the observed variations. The absorber is estimated ∼0.94 pc away from the central engine, which is where the outflow likely experiences deceleration due to the collision with the surrounding medium. This scheme is consistent with the argument that LoBAL QSOs may represent the transition from obscured star-forming galaxies to classic QSOs.

  8. Hydrogen Balmer Series Self-Absorption Measurement in Laser-Induced Air Plasma

    NASA Astrophysics Data System (ADS)

    Gautam, Ghaneshwar; Parigger, Christian

    2015-05-01

    In experimental studies of laser-induced plasma, we use focused Nd:YAG laser radiation to generate optical breakdown in laboratory air. A Czerny-Turner type spectrometer and an ICCD camera are utilized to record spatially and temporally resolved spectra. Time-resolved spectroscopy methods are employed to record plasma dynamics for various time delays in the range of 0.300 microsecond to typically 10 microsecond after plasma initiation. Early plasma emission spectra reveal hydrogen alpha and ionized nitrogen lines for time delays larger than 0.3 microsecond, the hydrogen beta line emerges from the free-electron background radiation later in the plasma decay for time delays in excess of 1 microsecond. The self-absorption analyses include comparisons of recorded data without and with the use of a doubling mirror. The extent of self-absorption of the hydrogen Balmer series is investigated for various time delays from plasma generation. There are indications of self-absorption of hydrogen alpha by comparison with ionized nitrogen lines at a time delay of 0.3 microsecond. For subsequent time delays, self-absorption effects on line-widths are hardly noticeable, despite the fact of the apparent line-shape distortions. Of interest are comparisons of inferred electron densities from hydrogen alpha and hydrogen beta lines as the plasma decays, including assessments of spatial variation of electron density.

  9. Hydrogen Balmer-alpha broadening in dense plasmas.

    PubMed

    Alexiou, S; Leboucher-Dalimier, E

    1999-09-01

    This work presents a theoretical analysis of experimental results for the hydrogen Balmer-alpha line in dense plasmas, with electron densities between 2x10(18) and 9x10(18) e/cm(3) A simulation of both electrons and ions is employed to produce reliable theoretical widths. These results are essentially in agreement with standard theory results and, for the most part, disagree with the experimental results. Consequently, either mechanisms not accounted for in the theoretical results (such as quadrupoles) are more important than previously thought at these densities, or else there is a problem in the experimental data (such as a possible reabsorption, which is not ruled out by the experimental data). PMID:11970167

  10. Calculation of auroral Balmer volume emission height profiles in the upper atmosphere

    NASA Astrophysics Data System (ADS)

    Sigernes, F.; Lorentzen, D. A.; Deehr, C. S.; Henriksen, K.

    1994-03-01

    Energetic protons entering the atmosphere will either travel as auroral protons or as neutral hydrogen atoms due to charge-exchange and excitation interactions with atmospheric constituents. Our objective is to develop a simple procedure to evaluate the Balmer excitation rates of H(sub alpha) and H(sub beta) and produce the corresponding volume emission rates vs height, using semi-empirical range relations in air, starting from proton spectra observed from rockets above the main collision region as measured by REASONER et al. (1968) and Soraas et al. (1974). The main assumptions are that the geomagnetic field is parallel and vertical, and that the pitch angle of the proton/hydrogen atom is preserved in collisions with atmospheric constituents before being thermalized. Calculations show that the largest energy losses occur in the height interval between 100 and 125 km, and the corresponding volume emission rate vs height profiles have maximum values in this height interval. The calculated volume emission rate height profile of H(sub beta) compares favorably with that measured with a rocket-borne photometer.

  11. Evolution of Balmer jump selected galaxies in the ALHAMBRA survey

    NASA Astrophysics Data System (ADS)

    Troncoso Iribarren, P.; Infante, L.; Padilla, N.; Lacerna, I.; Garcia, S.; Orsi, A.; Muñoz Arancibia, A.; Moustakas, J.; Cristóbal-Hornillos, D.; Moles, M.; Fernández-Soto, A.; Martínez, V. J.; Cerviño, M.; Alfaro, E. J.; Ascaso, B.; Arnalte-Mur, P.; Nieves-Seoane, L.; Benítez, N.

    2016-04-01

    Context. Samples of star-forming galaxies at different redshifts have been traditionally selected via color techniques. The ALHAMBRA survey was designed to perform a uniform cosmic tomography of the Universe, and we here exploit it to trace the evolution of these galaxies. Aims: Our objective is to use the homogeneous optical coverage of the ALHAMBRA filter system to select samples of star-forming galaxies at different epochs of the Universe and study their properties. Methods: We present a new color-selection technique, based on the models of spectral evolution convolved with the ALHAMBRA bands and the redshifted position of the Balmer jump to select star-forming galaxies in the redshift range 0.5 Balmer-jump Galaxies (BJGs). We applied the iSEDfit Bayesian approach to fit each detailed spectral energy distribution and determined star-formation rate (SFR), stellar mass, age, and absolute magnitudes. The mass of the halos in which these samples reside were found through a clustering analysis. Results: Five volume-limited BJG subsamples with different mean redshifts are found to reside in halos of median masses ~1012.5 ± 0.2 M⊙ slightly increasing toward z = 0.5. This increment is similar to numerical simulations results, which suggests that we trace the evolution of an evolving population of halos as they grow to reach a mass of ~1012.7 ± 0.1 at z = 0.5. The likely progenitors of our samples at z ~ 3 are Lyman-break galaxies, which at z ~ 2 would evolve into star-forming BzK galaxies, and their descendants in the local Universe are galaxies with luminosities of 1-3 L∗. Hence, this allows us to follow the putative evolution of the SFR, stellar mass, and age of these galaxies. Conclusions: From z ~ 1.0 to z ~ 0.5, the stellar mass of the volume-limited BJG samples changes almost not at all with redshift, suggesting that major mergers play a minor role in the evolution of these galaxies. The SFR evolution accounts for the small

  12. The Transition Zone in Balmer-dominated Shocks

    NASA Astrophysics Data System (ADS)

    Heng, Kevin; van Adelsberg, Matthew; McCray, Richard; Raymond, John C.

    2007-10-01

    We examine the structure of the postshock region in supernova remnants (SNRs). The ``shock transition zone'' is set up by charge transfer and ionization events between atoms and ions and has a width ~(1015 cm-2)n-10, where n0 is the total preshock density (including both atoms and ions). For Balmer-dominated SNRs with shock velocity vs>~1000 km s-1, the Rankine-Hugoniot conditions for ion velocity and temperature are obeyed instantly, leaving the full width at half-maximum (FWHM) of the broad Hα line versus vs relation intact. However, the spatial variation in the postshock densities is relevant to the problem of Lyα resonant scattering in young, core-collapse SNRs. Both two- (preshock atoms and ions) and three-component (preshock atoms, broad neutrals, and ions) models are considered. We compute the spatial emissivities of the broad (ξb) and narrow (ξn) Hα lines; a calculation of these emissivities in SN 1006 is in general agreement with the computed ones of Raymond and coworkers. The (dimensionless) spatial shift, Θshift, between the centroids of ξb and ξn is unique for a given shock velocity and fion, the preshock ion fraction. Measurements of Θshift can be used to constrain n0.

  13. Hydrogen Balmer alpha intensity distributions and line profiles from multiple scattering theory using realistic geocoronal models

    NASA Technical Reports Server (NTRS)

    Anderson, D. E., Jr.; Meier, R. R.; Hodges, R. R., Jr.; Tinsley, B. A.

    1987-01-01

    The H Balmer alpha nightglow is investigated by using Monte Carlo models of asymmetric geocoronal atomic hydrogen distributions as input to a radiative transfer model of solar Lyman-beta radiation in the thermosphere and atmosphere. It is shown that it is essential to include multiple scattering of Lyman-beta radiation in the interpretation of Balmer alpha airglow data. Observations of diurnal variation in the Balmer alpha airglow showing slightly greater intensities in the morning relative to evening are consistent with theory. No evidence is found for anything other than a single sinusoidal diurnal variation of exobase density. Dramatic changes in effective temperature derived from the observed Balmer alpha line profiles are expected on the basis of changing illumination conditions in the thermosphere and exosphere as different regions of the sky are scanned.

  14. Hour-timescale profile variations in the broad Balmer lines of the Seyfert galaxy Hour-timescale profile variations in the broad Balmer lines of the Seyfert galaxy Markarian 6

    NASA Astrophysics Data System (ADS)

    Asatrian, Norayr S.

    2014-07-01

    Part of results of the multi-epoch intranight optical spectroscopic monitoring of the Markarian 6 nucleus carried out at the telescopes of 6-m of the Special Astrophysical Observatory (Russia), 2.6-m of the Byurakan Astrophysical Observatory (Armenia) and 2-m of the Tautenburg Observatory (Germany) is presented. Observations were made in 1979, 1986, 1988-1991 and 2007-2009 during a total of 33 nights with an average sampling rate of 4 spectra per night. TV-scanner and long-slit spectrographs equipped with Image Tube and CCD detector arrays were used. Altogether we analyzed 110 Hβ and 58 Hα region spectra to search for intranight variability in the broad hydrogen emission line profiles. The typical spectral resolutions were 4 Å for scanner spectra, 6 Å for photographic spectra, and 5 Å and 10 Å for CCD spectra. The S/N ratio at the continuum level near the Hβ and Hα lines was in the range 15-50. The purpose of the search was to look for the characteristic variability signatures of different kinematical models of the broad emission-line region. We considered the centering and guiding errors which can result in differences between spectra. We found variations in the broad Balmer line difference profiles on time scale of hour with the level of significance of 3.6 σ to 5.0 σ. Variations take the form of narrow, small bumps located at the blue and red sides or only at the blue side of the lines. In the intermediate level of broad line flux, the Hβ and Hα profiles show fine structure. Detected profile changes occurred at the same radial velocity shifts as the details in the fine structure. The variability is at least 2 orders of magnitude more rapid than any observed for broad Balmer line profiles in AGNs that we are aware of in the literature. Discovered extremely rapid line-profile variability may be associated with reverberation effects. Two-sided profile changes may indicate the response of circularly rotating hydrogen clouds in the BLR to a light pulse

  15. HYDROGEN BALMER CONTINUUM IN SOLAR FLARES DETECTED BY THE INTERFACE REGION IMAGING SPECTROGRAPH (IRIS)

    SciTech Connect

    Heinzel, P.; Kleint, L.

    2014-10-20

    We present a novel observation of the white light flare (WLF) continuum, which was significantly enhanced during the X1 flare on 2014 March 29 (SOL2014-03-29T17:48). Data from the Interface Region Imaging Spectrograph (IRIS) in its near-UV channel show that at the peak of the continuum enhancement, the contrast at the quasi-continuum window above 2813 Å reached 100%-200% and can be even larger closer to Mg II lines. This is fully consistent with the hydrogen recombination Balmer-continuum emission, which follows an impulsive thermal and non-thermal ionization caused by the precipitation of electron beams through the chromosphere. However, a less probable photospheric continuum enhancement cannot be excluded. The light curves of the Balmer continuum have an impulsive character with a gradual fading, similar to those detected recently in the optical region on the Solar Optical Telescope on board Hinode. This observation represents a first Balmer-continuum detection from space far beyond the Balmer limit (3646 Å), eliminating seeing effects known to complicate the WLF detection. Moreover, we use a spectral window so far unexplored for flare studies, which provides the potential to study the Balmer continuum, as well as many metallic lines appearing in emission during flares. Combined with future ground-based observations of the continuum near the Balmer limit, we will be able to disentangle various scenarios of the WLF origin. IRIS observations also provide a critical quantitative measure of the energy radiated in the Balmer continuum, which constrains various models of the energy transport and deposit during flares.

  16. ALIEN: A nebular spectra analysis software

    NASA Astrophysics Data System (ADS)

    Cook, R.; Vazquez, R.

    2000-11-01

    A new C-coded software, designed to analyze nebular spectra, is presented. T his software is able to read the fluxes of the most important ions directly from IRAF's output file (splot.log). Spectra can be dereddened using the Balmer lines ratio and the Seaton's extinction law. Electron temperature and density, as well as ionic abundances by number are estimated by means of numeric calculations based on the five-level atom model. The dereddened spectra and the table containing the ionic abundances can be saved in a LaTex formatted file. This software has been initially designed to work with a low dispersion spectra.

  17. Inferring divertor plasma properties from hydrogen Balmer and Paschen series spectroscopy in JET-ILW

    NASA Astrophysics Data System (ADS)

    Lomanowski, B. A.; Meigs, A. G.; Sharples, R. M.; Stamp, M.; Guillemaut, C.; Contributors, JET

    2015-11-01

    A parametrised spectral line profile model is formulated to investigate the diagnostic scope for recovering plasma parameters from hydrogenic Balmer and Paschen series spectroscopy in the context of JET-ILW divertor plasmas. The separate treatment of Zeeman and Stark contributions in the line model is tested against the PPP-B code which accounts for their combined influence on the spectral line shape. The proposed simplified model does not fully reproduce the Stark-Zeeman features for the α and β transitions, but good agreement is observed in the line width and wing profiles, especially for n  >  5. The line model has been applied to infer radial density profiles in the JET-ILW divertor with generally good agreement between the D 5\\to 2 , 5\\to 3 , 6\\to 2 , 7\\to 2 and 9\\to 2 lines for high recycling and detached conditions. In an L-mode detached plasma pulse the Langmuir probe measurements typically underestimated the density by a factor 2-3 and overestimated the electron temperature by a factor of 5-10 compared to spectroscopically derived values. The line model is further used to generate synthetic high-resolution spectra for low-n transitions to assess the potential for parameter recovery using a multi-parametric fitting technique. In cases with 4 parameter fits with a single Maxwellian neutral temperature component the D 4\\to 3 line yields the best results with parameter estimates within 10% of the input values. For cases with 9 parameter fits inclusive of a multi-component neutral velocity distribution function the quality of the fits is degraded. Simultaneous fitting of the D 3\\to 2 and 4\\to 3 profiles improves the fit quality significantly, highlighting the importance of complementary spectroscopic measurements for divertor plasma emission studies.

  18. Black Hole Masses of Active Galaxies with Double-peaked Balmer Emission Lines

    NASA Astrophysics Data System (ADS)

    Lewis, Karen T.; Eracleous, Michael

    2006-05-01

    We have obtained near-IR spectra of five AGNs that exhibit double-peaked Balmer emission lines (NGC 1097, Pictor A, PKS 0921-213, 1E 0450.30-1817, and IRAS 0236.6-3101). The stellar velocity dispersions of the host galaxies were measured from the Ca II λλ8494, 8542, 8662 absorption lines and were found to range from 140 to 200 km s-1. Using the well-known correlation between the black hole mass and the stellar velocity dispersion, the black hole masses in these galaxies were estimated to range from 4×107 to 1.2×108 Msolar. We supplement the observations presented here with estimates of the black holes masses for five additional double-peaked emitters (Arp 102B, 3C 390.3, NGC 4579, NGC 4203, and M81) obtained by other authors using similar methods. Using these black hole masses, we infer the ratio of the bolometric luminosity to the Eddington luminosity, (Lbol/LEdd). We find that two objects (Pictor A and PKS 0921-213) have Lbol/LEdd~0.2, whereas the other objects have Lbol/LEdd<~10-2 (nearby, low-luminosity double-peaked emitters are the most extreme, with Lbol/LEdd<~10-4). The physical timescales in the outer regions of the accretion disks (at r~103GM/c2) in these objects were also estimated and range from a few months for the dynamical timescale to several decades for the sound crossing timescale. The profile variability in these objects is typically an order of magnitude longer than the dynamical time, but we note that variability occurring on the dynamical timescale has not been ruled out by the observations. Based on observations carried out at Cerro Tololo Inter-American Observatory, which is operated by AURA, Inc., under a cooperative agreement with the National Science Foundation.

  19. Broad Balmer-Line Absorption in SDSS J172341.10+555340.5

    NASA Astrophysics Data System (ADS)

    Aoki, Kentaro

    2010-10-01

    We present the discovery of Balmer-line absorption from Hα to H9 in an iron low-ionizaton broad absorption line (FeLoBAL) quasar, SDSS J172341.10+555340.5, by near-infrared spectroscopy with the Cooled Infrared Spectrograph and Camera for OHS (CISCO) attached to the Subaru Telescope. The redshift of the Balmer-line absorption troughs is 2.0530±0.0003, and it is blueshifted by 5370 km s-1 from the Balmer emission lines. It is more than 4000 km s-1 blueshifted from the previously known UV absorption lines. We detected relatively strong (EWrest = 20 Å) [OIII] emission lines that are similar to those found in other broad absorption line quasars with Balmer-line absorption. We also derived the column density of neutral hydrogen of 5.2 × 1017 cm-2 by using the curve of growth and taking account of Lyα trapping. We searched for UV absorption lines that had the same redshift with Balmer-line absorption, and found Ali III and Fe III absorption lines at z = 2.053 that correspond to previously unidentified absorption lines, and the presence of other blended troughs that were difficult to identify.

  20. New Observations of Balmer Continuum Flux in Solar Flares. Instrument Description and First Results

    NASA Astrophysics Data System (ADS)

    Kotrč, P.; Procházka, O.; Heinzel, P.

    2016-03-01

    Increase in the Balmer continuum radiation during solar flares was predicted by various authors, but has never been firmly confirmed observationally using ground-based slit spectrographs. Here we describe a new post-focal instrument, the image selector, with which the Balmer continuum flux can be measured from the whole flare area, in analogy to successful detections of flaring dMe stars. The system was developed and put into operation at the horizontal solar telescope HSFA2 of the Ondřejov Observatory. We measure the total flux by a fast spectrometer from a limited but well-defined region on the solar disk. Using a system of diaphragms, the disturbing contribution of a bright solar disk can be eliminated as much as possible. Light curves of the measured flux in the spectral range 350 - 440 nm are processed, together with the Hα images of the flaring area delimited by the appropriate diaphragm. The spectral flux data are flat-fielded, calibrated, and processed to be compared with model predictions. Our analysis of the data proves that the described device is sufficiently sensitive to detect variations in the Balmer continuum during solar flares. Assuming that the Balmer-continuum kernels have at least a similar size as those visible in Hα, we find the flux increase in the Balmer continuum to reach 230 - 550 % of the quiet continuum during the observed X-class flare. We also found temporal changes in the Balmer continuum flux starting well before the onset of the flare in Hα.

  1. Simultaneous measurements of the hydrogen airglow emissions of Lyman alpha, Lyman beta, and Balmer alpha.

    NASA Technical Reports Server (NTRS)

    Weller, C. S.; Meier, R. R.; Tinsley, B. A.

    1971-01-01

    Comparison of Lyman-alpha, 740- to 1050-A, and Balmer-alpha airglow measurements made at 134 deg solar-zenith angle on Oct. 13, 1969, with resonance-scattering models of solar radiation. Model comparison with Lyman-alpha data fixes the hydrogen column abundance over 215 km to 2 x 10 to the 13th per cu cm within a factor of 2. Differences between the Lyman-alpha model and data indicate a polar-equatorial departure from spherical symmetry in the hydrogen distribution. A Lyman-beta model based on the hydrogen distribution found to fit the Lyman-alpha data fits the spatial variation of the 740- to 1050-A data well from 100 to 130 km, but it does not fit the data well at higher altitudes; thus the presence of more rapidly absorbed shorter-wavelength radiation is indicated. This same resonance-scattering model yields Balmer-alpha intensities that result in good spatial agreement with the Balmer-alpha measurements, but a fivefold increase in the measured solar line center Lyman-beta flux is required (as required for the Lyman-beta measurement). The intensity ratio of Lyman-beta and Balmer-alpha at night is found to be a simple measure of the hydrogen optical depth if measurements with good accuracy can be made in the visible and ultraviolet spectrum.

  2. BLACK HOLE MASS ESTIMATES BASED ON C IV ARE CONSISTENT WITH THOSE BASED ON THE BALMER LINES

    SciTech Connect

    Assef, R. J.; Denney, K. D.; Kochanek, C. S.; Peterson, B. M.; Kozlowski, S.; Dietrich, M.; Grier, C. J.; Khan, R.; Ageorges, N.; Buschkamp, P.; Gemperlein, H.; Hofmann, R.; Barrows, R. S.; Falco, E.; Kilic, M.; Feiz, C.; Germeroth, A.; Juette, M.; Knierim, V.; Laun, W.; and others

    2011-12-01

    Using a sample of high-redshift lensed quasars from the CASTLES project with observed-frame ultraviolet or optical and near-infrared spectra, we have searched for possible biases between supermassive black hole (BH) mass estimates based on the C IV, H{alpha}, and H{beta} broad emission lines. Our sample is based upon that of Greene, Peng, and Ludwig, expanded with new near-IR spectroscopic observations, consistently analyzed high signal-to-noise ratio (S/N) optical spectra, and consistent continuum luminosity estimates at 5100 A. We find that BH mass estimates based on the full width at half-maximum (FWHM) of C IV show a systematic offset with respect to those obtained from the line dispersion, {sigma}{sub l}, of the same emission line, but not with those obtained from the FWHM of H{alpha} and H{beta}. The magnitude of the offset depends on the treatment of the He II and Fe II emission blended with C IV, but there is little scatter for any fixed measurement prescription. While we otherwise find no systematic offsets between C IV and Balmer line mass estimates, we do find that the residuals between them are strongly correlated with the ratio of the UV and optical continuum luminosities. This means that much of the dispersion in previous comparisons of C IV and H{beta} BH mass estimates are due to the continuum luminosities rather than to any properties of the lines. Removing this dependency reduces the scatter between the UV- and optical-based BH mass estimates by a factor of approximately two, from roughly 0.35 to 0.18 dex. The dispersion is smallest when comparing the C IV {sigma}{sub l} mass estimate, after removing the offset from the FWHM estimates, and either Balmer line mass estimate. The correlation with the continuum slope is likely due to a combination of reddening, host contamination, and object-dependent SED shapes. When we add additional heterogeneous measurements from the literature, the results are unchanged. Moreover, in a trial observation of a

  3. THE BALMER-DOMINATED BOW SHOCK AND WIND NEBULA STRUCTURE OF {gamma}-RAY PULSAR PSR J1741-2054

    SciTech Connect

    Romani, Roger W.; Shaw, Michael S.; Camilo, Fernando; Cotter, Garret; Sivakoff, Gregory R. E-mail: msshaw@stanford.ed

    2010-12-01

    We have detected an H{alpha} bow shock nebula around PSR J1741-2054, a pulsar discovered through its GeV {gamma}-ray pulsations. The pulsar is only {approx}1.''5 behind the leading edge of the shock. Optical spectroscopy shows that the nebula is non-radiative, dominated by Balmer emission. The H{alpha} images and spectra suggest that the pulsar wind momentum is equatorially concentrated and implies a pulsar space velocity {approx}150 km s{sup -1}, directed 15{sup 0} {+-} 10{sup 0} out of the plane of the sky. The complex H{alpha} profile indicates that different portions of the post-shock flow dominate line emission as gas moves along the nebula and provide an opportunity to study the structure of this unusual slow non-radiative shock under a variety of conditions. CXO ACIS observations reveal an X-ray pulsar wind nebula within this nebula, with a compact {approx}2.''5 equatorial structure and a trail extending several arcminutes behind. Together these data support a close ({<=}0.5 kpc) distance, a spin geometry viewed edge-on, and highly efficient {gamma}-ray production for this unusual, energetic pulsar.

  4. Hydrogen recycling study by Balmer lines emissions in linear plasma machine TPE

    NASA Astrophysics Data System (ADS)

    Shimada, K.; Tanabe, T.; Causey, R.; Venhaus, T.; Okuno, K.

    2001-03-01

    We have investigated the influence of target materials and temperatures on Balmer series emission in a linear plasma apparatus, Tritium Plasma Experiment (TPE). The intensities of the Balmer series emission in front of the target were higher for heavier mass target and also for lower target temperature, showing rather linear relationship between the emission intensity and hydrogen reflection coefficient. For exothermic hydrogen occluders of Ti and Ta, the intensity ratio of Dβ/ Dα increased with the target temperature markedly, whereas the intensity ratio stayed rather constant for endothermic hydrogen occluders of Ni, Cu and W. This is a clear demonstration that the target materials and temperatures modify the boundary plasma. In addition the intensity ratio Dβ/Dα is not simply a function of plasma temperature but has clear target temperature dependence.

  5. Remote sensing and geologic studies of the Balmer-Kapteyn region of the Moon

    NASA Astrophysics Data System (ADS)

    Hawke, B. Ray; Gillis, J. J.; Giguere, T. A.; Blewett, D. T.; Lawrence, D. J.; Lucey, P. G.; Smith, G. A.; Spudis, P. D.; Taylor, G. Jeffrey

    2005-06-01

    The Balmer-Kapteyn (B-K) region is located just east of Mare Fecunditatis on the east limb of the Moon. It is centered on the Balmer-Kapteyn basin, a pre-Nectarian impact structure that exhibits two rings, approximately 225 km and 450 km in diameter. Clementine multispectral images and Lunar Prospector (LP) gamma-ray spectrometer (GRS) data were used to investigate the composition, age, and origin of geologic units in the region. A major expanse of cryptomare was mapped within the B-K basin. Spectral and chemical data obtained for dark-haloed craters (DHCs) established that these impact craters excavated mare basalt from beneath higher-albedo, highland-rich surface units. The buried basalts exposed by DHCs in the region are dominated by low-titanium mare basalts. The fresh DHC FeO values (15.0-15.7 wt.%) that best represent those of buried mare basalts are well within the range of values exhibited by high-alumina mare basalts. While most cryptomare deposits occur beneath surfaces that range in age from Imbrian to Nectarian, it is possible that some mare flows were emplaced during pre-Nectarian time. Most cryptomare deposits in the B-K region were formed by the contamination of mare surfaces by highland-rich distal ejecta from surrounding impact craters. These Balmer-type cryptomare deposits are usually associated with light plains units. Major LP-GRS FeO enhancements are associated with cryptomaria in the Balmer-Kapteyn, Lomonosov-Fleming, Schiller-Schickard, and Mendel-Rydberg regions.

  6. Resolution of the discrepancy between Balmer alpha emission rates, the solar Lyman beta flux, and models of geocoronal hydrogen concentration

    NASA Technical Reports Server (NTRS)

    Levasseur, A.-C.; Meier, R. R.; Tinsley, B. A.

    1976-01-01

    New satellite Balmer alpha measurements and solar Lyman beta flux and line profile measurements, together with new measurements of the zodiacal light intensity used in correcting both ground and satellite Balmer alpha measurements for the effects of the Fraunhofer line in the zodiacal light, have been used in a reevaluation of the long-standing discrepancy between ground-based Balmer alpha emission rates and other geocoronal hydrogen parameters. The solar Lyman beta line center flux is found to be (4.1 plus or minus 1.3) billion photons per sq cm per sec per angstrom at S(10.7) equals 110 and, together with a current hydrogen model which has 92,000 atoms per cu cm at 650 km for T(inf) equals 950 K, gives good agreement between calculated Balmer alpha emission rates and the ground-based and satellite measurements.

  7. Physical properties of Be star envelopes from Balmer and Fe II emission lines

    NASA Astrophysics Data System (ADS)

    Slettebak, Arne; Collins, George W., II; Truax, Ryland

    1992-07-01

    The study obtains H-alpha, B-beta, H-gamma, and Fe II 6516 line profiles with resolution 0.45 A for 41 bright Be stars with a CCD detonator during two observing periods in 1989. Analysis of the structure of the emission profiles indicates that the Be star emitting envelope is most likely axially symmetric, consistent with a rotating, equatorial disk. A number of Be stars show either a 'wine bottle' structure or inflection points on one side of their H-alpha emission profiles, suggesting a two-component structure for the emitting envelope: an inner disk, possibly turbulent, and an outer extended disk. Differentially rotating disks producing weak H-alpha emission are closer to the central star where rotation broadens the line more strongly, relative to stars with extended envelopes which emit strongly but rotate more slowly. From the Balmer emission decrements it is found that Be star envelopes with Te near 10,000 K have electron densities in the range 10 exp 11 to 10 exp 13/cu cm. Be stars with weak Balmer emission have, on average, somewhat flatter Balmer decrements than stars with strong emission, suggesting envelopes with higher electron densities.

  8. A Possible Solution to the Lyman/Balmer Line Problem in Hot DA White Dwarfs

    NASA Astrophysics Data System (ADS)

    Preval, Simon P.; Barstow, Martin A.; Badnell, Nigel R.; Holberg, Jay B.; Hubeny, Ivan

    2015-06-01

    Arguably, the best method for determining the effective temperature (Teff) and surface gravity (log g) of a DA white dwarf is by fitting the Hydrogen Lyman and Balmer absorption features. However, as has been shown for white dwarfs with Teff>50,000K, the calculated value from the Lyman and Balmer lines are discrepant, which worsens with increasing temperature. Many different solutions have been suggested, ranging from the input physics used to calculate the models, to interstellar reddening. We will focus on the former, and consider three variables. The first is the atomic data used, namely the number of transitions included in line blanketing treatments and the photoionization cross sections. The second is the stark broadening treatment used to synthesise the Lyman and Balmer line profiles, namely the calculations performed by Lemke (1997) and Tremblay & Bergeron (2009). Finally, the third is the atmospheric content. The model grids are calculated with a pure H composition, and a metal polluted composition using the abundances of Preval et al. (2013). We present the preliminary results of our analysis, whereby we have determined the Teff for a small selection of white dwarfs. We plan to extend our analysis by allowing metallicity to vary in future model grids.

  9. Second Epoch Hubble Space Telescope Observations of Kepler's Supernova Remnant: The Proper Motions of Balmer Filaments

    NASA Astrophysics Data System (ADS)

    Sankrit, Ravi; Raymond, John C.; Blair, William P.; Long, Knox S.; Williams, Brian J.; Borkowski, Kazimierz J.; Patnaude, Daniel J.; Reynolds, Stephen P.

    2016-01-01

    We report on the proper motions of Balmer-dominated filaments in Kepler’s supernova remnant using high resolution images obtained with the Hubble Space Telescope at two epochs separated by about 10 years. We use the improved proper motion measurements and revised values of shock velocities to derive a distance to Kepler of {5.1}-0.7+0.8 kpc. The main shock around the northern rim of the remnant has a typical speed of 1690 km s-1 and is encountering material with densities of about 8 cm-3. We find evidence for the variation of shock properties over small spatial scales, including differences in the driving pressures as the shock wraps around a curved cloud surface. We find that the Balmer filaments ahead of the ejecta knot on the northwest boundary of the remnant are becoming fainter and more diffuse. We also find that the Balmer filaments associated with circumstellar material in the interior regions of the remnant are due to shocks with significantly lower velocities and that the brightness variations among these filaments trace the density distribution of the material, which may have a disk-like geometry. Based on observations made with the Hubble Space Telescope.

  10. Hydrogen Balmer line formation in solar flares affected by return currents

    NASA Astrophysics Data System (ADS)

    Štepán, J. Å.; Kašparová, J.; Karlický, M.; Heinzel, P.

    2007-09-01

    Aims:We investigate the effect of the electric return currents in solar flares on the profiles of hydrogen Balmer lines. We consider the monoenergetic approximation for the primary beam and runaway model of the neutralizing return current. Methods: Propagation of the 10 keV electron beam from a coronal reconnection site is considered for the semiempirical chromosphere model F1. We estimate the local number density of return current using two approximations for beam energy fluxes between 4 × 1011 and 1 × 1012 erg cm-2 s-1. Inelastic collisions of beam and return-current electrons with hydrogen are included according to their energy distributions, and the hydrogen Balmer line intensities are computed using an NLTE radiative transfer approach. Results: In comparison to traditional NLTE models of solar flares that neglect the return-current effects, we found a significant increase emission in the Balmer line cores due to nonthermal excitation by return current. Contrary to the model without return current, the line shapes are sensitive to a beam flux. It is the result of variation in the return-current energy that is close to the hydrogen excitation thresholds and the density of return-current electrons.

  11. Balmer profiles in the geocorona and interstellar space. I - Asymmetries due to fine structure

    NASA Technical Reports Server (NTRS)

    Chamberlain, Joseph W.

    1987-01-01

    While the Doppler profiles of Balmer-alpha and -beta are in principle analyzable in order to derive orbital data concerning both escaping and satellite geocoronal particles, interpretations are in practice hampered by a lack of understanding of profile properties apart from such geocoronal features as an asymmetry, caused by the absence of escape velocity-exceeding, downward-directed particles. Attention is accordingly given to the profiles of H atoms which, while emitting radiation from a complete Maxwellian distribution, also exhibit an H-alpha fine structure-generated asymmetry which is a predictable function of the excitation mechanism.

  12. Balmer-beta line asymmetry characteristics in a high pressure, microwave-produced argon plasma.

    PubMed

    Palomares, J M; Torres, J; Gigosos, M A; van der Mullen, J J A M; Gamero, A; Sola, A

    2009-11-01

    This paper presents a study on the asymmetry of the Balmer H(beta) profile in plasmas produced by microwaves at high pressure with the help of some functions of asymmetry for the whole profile, as well as by means of some specific parameters characterizing only its central dip. The study shows how this asymmetry--very low in our case--depends on the electron density and flux of gases and how the existence of inhomogeneities in the plasma can affect the shape and symmetry of this line. Also, limitations on the determination of the asymmetry are pointed out and the use of this profile for plasma diagnosis is discussed. PMID:19891830

  13. LS Pegasi: A Low-Inclination SW Sextantis-Type Cataclysmic Binary with High-Velocity Balmer Emission-Line Wings

    NASA Astrophysics Data System (ADS)

    Taylor, Cynthia J.; Thorstensen, John R.; Patterson, Joseph

    1999-02-01

    We present time-resolved spectroscopy and photometry of the bright cataclysmic variable LS Peg (=S193; V~13.0-Szkody et al.). The Balmer lines exhibit broad, asymmetric wings Doppler-shifted by about 2000 km s^-1 at the edges, while the He I lines show phase-dependent absorption features strikingly similar to SW Sextantis stars, as well as emission through most of the phase. The C III/N III emission blend does not show any phase dependence. From velocities of Hα emission lines, we determine an orbital period of 0.174774+/-0.000003 days (=4.1946 hr), which agrees with Szkody's value of approximately 4.2 hr. No stable photometric signal was found at the orbital period. A noncoherent quasi-periodic photometric signal was seen at a period of 20.7+/-0.3 minutes. The high-velocity Balmer wings most probably arise from a stream reimpact point close to the white dwarf. We present simulated spectra based on a kinematic model similar to the modified disk-overflow scenario of Hellier & Robinson. The models reproduce the broad line wings, though some other details are unexplained. Using an estimate of dynamical phase based on the model, we show that the phasing of the emission- and absorption-line variations is consistent with that in (eclipsing) SW Sex stars. We therefore identify LS Peg as a low-inclination SW Sex star. Our model suggests i=30^deg, and the observed absence of any photometric signal at the orbital frequency establishes i<60^deg. This constraint puts a severe strain on interpretations of the SW Sex phenomenon which rely on disk structures lying slightly out of the orbital plane.

  14. The variability of the double-peaked Balmer lines in the active nucleus of NGC 1097

    NASA Technical Reports Server (NTRS)

    Storchi-Bergmann, Thaisa; Eracleous, Michael; Livio, Mario; Wilson, Andrew S.; Filippenko, Alexei V.; Halpern, Jules P.

    1995-01-01

    We present spectroscopic observations of the nucleus of the Seyfert/low-ionization nuclear emission-line region galaxy NGC 1097 spanning the period 1991-1994. The goal was to monitor anticipated variations of the broad, double-peaked Balmer lines which appeared abruptly in 1991. We find that the broad Balmer lines have varied significantly over the monitoring period, both in their integrated fluxes and in their profile shapes. The integrated H-alpha flux has decreased by a factor of 2, the (H-alpha)/(H-beta) ratio has increased, and the originally asymmetric H-alpha profile has become symmetric. The decline of the H-alpha flux and the change in the (H-alpha)/(H-beta) ratio can be interpreted as consequences of either increased obscuration along the line of sight, or a decline in the ionizing continuum, but neither of these scenarios can account for the change in profile shapes. A model attributing the line emission to a precessing elliptical ring around a 10(exp 6) solar mass nuclear black hole can reproduce the observed profile variations. In this scenario, the line-emitting ring is the result of the tidal disruption of a star by the black hole. Alternative scenarios associating the broad-line emission with a collimated bipolar outflow also remain viable, but binary black holes and inhomogeneous accretion disks are disfavored by the observed pattern of variability.

  15. Spatially Resolved Dust Maps from Balmer Decrements in Galaxies at z ~ 1.4

    NASA Astrophysics Data System (ADS)

    Nelson, Erica June; van Dokkum, Pieter G.; Momcheva, Ivelina G.; Brammer, Gabriel B.; Wuyts, Stijn; Franx, Marijn; Förster Schreiber, Natascha M.; Whitaker, Katherine E.; Skelton, Rosalind E.

    2016-01-01

    We derive average radial gradients in the dust attenuation toward H ii regions in 609 galaxies at z ˜ 1.4, using measurements of the Balmer decrement out to r ˜ 3 kpc. The Balmer decrements are derived from spatially resolved maps of Hα and Hβ emission from the 3D-HST survey. We find that with increasing stellar mass M both the normalization and strength of the gradient in dust attenuation increases. Galaxies with a mean mass of < {log} M> =9.2M⊙ have little dust attenuation at all radii, whereas galaxies with < {log} M> =10.2M⊙ have AHα ≈ 2 mag in their central regions. We parameterize this as {A}{{H}α }=b+c{log} r, with b=0.9+{log}1.0{M}10, c = -1.9-2.2 log M10, r in kpc, and M10 the stellar mass in units of 1010 M⊙. This expression can be used to correct spatially resolved measurements of Hα to radial distributions of star formation. When applied to our data, we find that the star formation rates (SFRs) in the central r < 1 kpc of galaxies in the highest mass bin are ˜6 M⊙ yr-1, six times higher than before correction and approximately half of the total SFR of these galaxies. If this high central SFR is maintained for several Gyr, a large fraction of the stars in present-day bulges likely formed in situ.

  16. Stationary Inverted Balmer and Lyman populations for a CW HI water-plasma laser

    NASA Astrophysics Data System (ADS)

    Mills, Randell L.

    2002-10-01

    Stationary inverted H Balmer and Lyman populations were observed from a low pressure water-vapor microwave discharge plasma. The ionization and population of excited atomic hydrogen levels was attributed to energy provided by a catalytic resonance energy transfer between hydrogen atoms and molecular oxygen formed in the water plasma. The catalysis mechanism was supported by the observation of O^2+ and H Balmer line broadening of 55 eV compared to 1 eV for hydrogen alone. The high hydrogen atom temperature with a relatively low electron temperature, Te = 2 eV, exhibited characteristics of cold recombining plasmas. These conditions of a water plasma favored an inverted population in the lower levels. Thus, the catalysis of atomic hydrogen may pump a cw HI laser. From our results, laser oscillations are may be possible from (i) n = 3, n = 4, n = 5, n = 6, n = 7, and n = 8 to n = 2, (ii) n = 4, n = 5, n = 6, and n = 7 to n = 3 and (iii) n = 5 and n = 6 to n = 4. Lines of the Balmer series of n = 5, and n = 6 to n = 2 and the Paschen series of n = 5 to n = 3 were of particular importance because of the potential to design blue and 1.3 micron infrared lasers, respectively, which are ideal for many communications and microelectronics applications. At a microwave input power of 9W/cm^3, a collisional radiative model showed that the hydrogen excited state population distribution was consistent with an n = 1arrow5,6 pumping power of an unprecedented 200W/cm^3. High power hydrogen gas lasers are anticipated at wavelengths, over a broad spectral range from far infrared to violet which may be miniaturized to micron dimensions. Such a hydrogen laser represents the first new atomic gas laser in over a decade, and it may prove to be the most efficient, versatile, and useful of all. A further application is the direct generation of electrical power using photovoltaic conversion of the spontaneous or stimulated water vapor plasma emission.

  17. Modelling of passive spectroscopy in the ITER divertor: the first hydrogen Balmer lines

    NASA Astrophysics Data System (ADS)

    Rosato, J.; Kotov, V.; Reiter, D.

    2010-07-01

    The first lines of the hydrogen Balmer series are investigated in ITER divertor conditions using a line shape code and a plasma edge transport code. It is shown that most of the emissivity originates from a localized, cold and dense region close to the divertor target plates, where the plasma is in the recombining regime. We simulate the signal obtained by pointing a spectrometer at this zone. The physical processes which contribute to the spectral line formation are examined, with a special emphasis on the Stark effect, photon absorption and stimulated emission. It is shown that, even though the Stark effect is significant, local information on the Doppler atomic temperature can be obtained from a fitting analysis of the Dα spectral line shape.

  18. Stimulated emission and the flat Balmer decrements of cataclysmic variable stars

    NASA Technical Reports Server (NTRS)

    Elitzur, M.; Ferland, G. J.; Mathews, S. G.; Shields, G. A.

    1983-01-01

    Balmer emission lines from cataclysmic variables often have nearly equal intensities rather than the rapid decrement predicted by simple nebular theory. Traditionally, this has been interpreted in terms of local thermodynamic equilibrium emission from a dense gas with small volume located just above the accretion disk. It is shown that the intense radiation field within a close binary system can affect excited state populations and optical emission in ways which allow a relatively low density gas to closely mimic the high density situation. In at least one case, the old nova V603 Aql, the emitting gas has a low density and nearly fills the orbital plane of the system. If this is characteristic of other systems, then the determination of orbital parameters and masses of cataclysmic variables from emission line radial velocities, as well as the prediction of soft X-ray emission from accreting binaries, will be affected.

  19. Hydrogen Balmer series measurements and determination of Rydberg's constant using two different spectrometers

    NASA Astrophysics Data System (ADS)

    Amrani, D.

    2014-07-01

    This paper investigates the use of two different methods, the optical and the computer-aided diffraction-grating spectrometer, to measure the wavelength of visible lines of Balmer series from the hydrogen atomic spectrum and estimate the value of Rydberg's constant. Analysis and interpretation of data showed that both methods, despite their difference in terms of the type of equipment used, displayed good performance in terms of precision of measurements of wavelengths of spectral lines. A comparison was carried out between the experimental value of Rydberg's constant obtained with both methods and the accepted value. The results of Rydberg's constant obtained with both the optical and computer-aided spectrometers were 1.099 28 × 10-7 m-1 and 1.095 13 × 10-7 m-1 with an error difference of 0.17% and 0.20% compared to the accepted value 1.097 373 × 10-7 m-1, respectively.

  20. A Guided-Inquiry Lab for the Analysis of the Balmer Series of the Hydrogen Atomic Spectrum

    ERIC Educational Resources Information Center

    Bopegedera, A. M. R. P.

    2011-01-01

    A guided-inquiry lab was developed to analyze the Balmer series of the hydrogen atomic spectrum. The emission spectrum of hydrogen was recorded with a homemade benchtop spectrophotometer. By drawing graphs and a trial-and-error approach, students discover the linear relationship presented in the Rydberg formula and connect it with the Bohr model…

  1. Doppler shift measurement of Balmer-alpha line spectrum emission from a plasma in a negative hydrogen ion source

    SciTech Connect

    Wada, M. Doi, K.; Kisaki, M.; Nakano, H.; Tsumori, K.; Nishiura, M.

    2015-04-08

    Balmer-α light emission from the extraction region of the LHD one-third ion source has shown a characteristic Doppler broadening in the wavelength spectrum detected by a high resolution spectrometer. The spectrum resembles Gaussian distribution near the wavelength of the intensity peak, while it has an additional component of a broader foot. The measured broadening near the wavelength of the intensity peak corresponds to 0.6 eV hydrogen atom temperature. The spectrum exhibits a larger expansion in the blue wing which becomes smaller when the line of sight is tilted toward the driver region from the original observation axis parallel to the plasma grid. A surface collision simulation model predicts the possibility of hydrogen reflection at the plasma grid surface to form a broad Balmer-α light emission spectrum.

  2. Star formation activity in Balmer break galaxies at z< 1.5

    NASA Astrophysics Data System (ADS)

    Díaz Tello, J.; Donzelli, C.; Padilla, N.; Akiyama, M.; Fujishiro, N.; Yoshikawa, T.; Hanami, H.

    2016-03-01

    Aims: We present a spectroscopic study of the properties of 64 Balmer break galaxies that show signs of star formation. The studied sample of star-forming galaxies spans a redshift range from 0.094 to 1.475 with stellar masses in the range 108-1012M⊙. The sample also includes eight broad emission line galaxies with redshifts between 1.5

  3. Data-model comparison search analysis of coincident PBO Balmer α, EURD Lyman β geocoronal measurements from March 2000

    NASA Astrophysics Data System (ADS)

    Bishop, J.; Mierkiewicz, E. J.; Roesler, F. L.; Gómez, J. F.; Morales, C.

    2004-05-01

    Recent Lyman series and Balmer series airglow measurements provide a fresh opportunity to investigate the density distribution and variability of atomic hydrogen in the upper atmosphere. Dedicated nightside Balmer α Fabry-Perot spectrometer measurements at the Pine Bluff Observatory (PBO), University of Wisconsin-Madison, have been acquired since late 1999 taking advantage of several technological advances. Extreme ultraviolet spectral radiance measurements by the Espectrógrafo Ultravioleta extremo para la Radiación Difusa (EURD) instrument on the Spanish MINISAT-1 satellite from October 1997 to December 2001 provide extensive sets of geocoronal Lyman β, Lyman γ and He 584 Å emission intensities. In this paper, coincident EURD Lyman β and PBO Balmer α radiance measurements from the early March 2000 new moon period are presented. In addition to serving as examples of the data sets now available, the data volume poses an analysis challenge not faced in prior geocoronal studies. A data-model comparison search procedure employing resonance radiation transport results for extensive sets of parametric density distribution models is being developed for use in analyses of multiple large data sets; this is described, and example results for the PBO and EURD March 2000 data sets are presented. The tightness of the constraints obtained for the solar line-center Lyman β irradiance and the atomic hydrogen column abundance is somewhat surprising, given the crudeness of the parameter binning in the search procedure and the fact that a small number of recognized corrections remain to be made to each data set.

  4. The Balmer-dominated northeast limb of the Cygnus loop supernova remnant

    NASA Technical Reports Server (NTRS)

    Hester, J. Jeff; Raymond, John C.; Blair, William P.

    1994-01-01

    We present a comprehensive investigation of the Balmar-dominated northeast limb of the Cygnus Loop supernova remnant. Data presented include H alpha (O III), and X-ray images, UV and visible spectrophotometry, and high-resolution spectroscophy. The two relatively bright Balmer-dominated filaments visible on the POSS prints are seen to be part of a very smooth and regular complex of filaments. These filaments mark the current location of the blast wave and are seen to bound the sharply limb-brightened X-ray emission, including the previously reported X-ray, 'halo.' The (O III)/h beta ratio throughout the region is approximately 0.1, except for regions in which the shock is undergoing a transition from nonradiative to incomplete radiative to incomplete radiative conditions. At these locations (O III) emission from the cooling region is quite strong, while collisionally excited Balmer-line emission can be weak because of photoionization of the preshock medium by UV from the nascent cooling region. As a result (O III)/H beta is greater than 100 in some locations. The nonradiative/radiative transition is best studied along the length of the northwestern of the two brightest filaments, where the shock velocity and swept-up column go from approximately 180 km/s and 10(exp 17)/sq cm at one end to approximately 140 km/s and 8 x 10(exp 17)/cm at the other. There are also a number of locations of such incomplete radiative emission where the shock has recently encountered denser regions with characteristic sizes of approximately 10(exp 18) cm. There is a considerable amount of evidence that the shock has decelerated from approximately 400 km/s to less than 200 km/s in the last 1000 yr. We interpret this as the result of the blast wave hitting the wall of a cavity which surround the supernova precursor and succeed in matching a wide range of data with a reflected shock model in which the density ofthe cavity wall is approximately 1.2/cu cm and the density in the interior of the

  5. Star formation in NGC 4449: MAMA-detector UV imagery and Fabry-Perot Balmer-line imagery

    NASA Technical Reports Server (NTRS)

    Hill, Robert S.; Home, Allen T.; Smith, Andrew M.; Bruhweiler, Fred C.; Cheng, K.P.; Hintzen, Paul M. N.; Oliversen, Ronald J.

    1994-01-01

    Using far-ultraviolet (FUV) and Balmer-line imagery, we investigate the star formation history of 22 large OB complexes in the Magellanic irregular galaxy NGC 4449. The FUV luminosity of NGC 4449 is comparable to those of late-type spirals and is greater than that of the LMC by approximately 2.4 mag, indicating substantial star formation in the last 10(exp 8) yr. FUV data were taken using a sounding-rocket telescope with a Multianode Microchannel Array (MAMA) detector, and Balmer-line data were taken using the Goddard Fabry-Perot Imager. The resulting imagery shows bright, roughly coincident FUV and H alpha sources throughout the extent of the visible galaxy. We model these sources using cluster-evolution codes. Although all sources are a few Myr old, clear age differences are found. In particular, several of the most recently active star formation regions are located together in the galaxy's northern periphery, which is apparently coincident with a large H I reservoir. The brightest and most massive OB complexes are found along the northeast-southwest surface brightness ridgeline (the 'bar'). Over the entire galaxy, star formation rates are consistent on timescales of 10(exp 6), 10(exp 8), and 10(exp 9) yr. A history of recent star formation is suggested with two main episodes, one predominantly in the bar ending approximately 5 Myr ago, and an ongoing one associated with an observed H I cloud.

  6. Constraining sub-parsec binary supermassive black holes in quasars with multi-epoch spectroscopy. II. The population with kinematically offset broad Balmer emission lines

    SciTech Connect

    Liu, Xin; Shen, Yue; Bian, Fuyan; Loeb, Abraham; Tremaine, Scott

    2014-07-10

    A small fraction of quasars have long been known to show bulk velocity offsets (of a few hundred to thousands of km s{sup –1}) in the broad Balmer lines with respect to the systemic redshift of the host galaxy. Models to explain these offsets usually invoke broad-line region gas kinematics/asymmetry around single black holes (BHs), orbital motion of massive (∼sub-parsec (sub-pc)) binary black holes (BBHs), or recoil BHs, but single-epoch spectra are unable to distinguish between these scenarios. The line-of-sight (LOS) radial velocity (RV) shifts from long-term spectroscopic monitoring can be used to test the BBH hypothesis. We have selected a sample of 399 quasars with kinematically offset broad Hβ lines from the Sloan Digital Sky Survey (SDSS) Seventh Data Release quasar catalog, and have conducted second-epoch optical spectroscopy for 50 of them. Combined with the existing SDSS spectra, the new observations enable us to constrain the LOS RV shifts of broad Hβ lines with a rest-frame baseline of a few years to nearly a decade. While previous work focused on objects with extreme velocity offset (>10{sup 3} km s{sup –1}), we explore the parameter space with smaller (a few hundred km s{sup –1}) yet significant offsets (99.7% confidence). Using cross-correlation analysis, we detect significant (99% confidence) radial accelerations in the broad Hβ lines in 24 of the 50 objects, of ∼10-200 km s{sup –1} yr{sup –1} with a median measurement uncertainty of ∼10 km s{sup –1} yr{sup –1}, implying a high fraction of variability of the broad-line velocity on multi-year timescales. We suggest that 9 of the 24 detections are sub-pc BBH candidates, which show consistent velocity shifts independently measured from a second broad line (either Hα or Mg II) without significant changes in the broad-line profiles. Combining the results on the general quasar population studied in Paper I, we find a tentative anti-correlation between the velocity offset in the

  7. The peculiar balmer decrement of SN 2009ip: Constraints on circumstellar geometry

    SciTech Connect

    Levesque, Emily M.; Stringfellow, Guy S.; Bally, John; Keeney, Brian A.; Ginsburg, Adam G.

    2014-01-01

    We present optical and near-IR spectroscopic observations of the luminous blue variable SN 2009ip during its remarkable photometric evolution of 2012. The spectra sample three key points in the SN 2009ip light curve, corresponding to its initial brightening in August (2012-A) and its dramatic rebrightening in early October (2012-B). Based on line fluxes and velocities measured in our spectra, we find a surprisingly low I(Hα)/I(Hβ) ratio (∼1.3-1.4) in the 2012-B spectra. Such a ratio implies either a rare Case B recombination scenario where Hα, but not Hβ, is optically thick, or an extremely high density for the circumstellar material of n{sub e} > 10{sup 13} cm{sup –3}. The Hα line intensity yields a minimum radiating surface area of ≳20,000 AU{sup 2} in Hα at the peak of SN 2009ip's photometric evolution. Combined with the nature of this object's spectral evolution in 2012, a high circumstellar density and large radiating surface area imply the presence of a thin disk geometry around the central star (and, consequently, a possible binary companion), suggesting that the observed 2012-B rebrightening of SN 2009ip can be attributed to the illumination of the disk's inner rim by fast-moving ejecta produced by the underlying events of 2012-A.

  8. Measurement and Simulation of Deuterium Balmer-Alpha Emission from First-Orbit Fast Ions and the Application to Neutral Density and General Fast-Ion Loss Detection in the DIII-D Tokamak

    NASA Astrophysics Data System (ADS)

    Bolte, Nathan Glynn

    Spectra of the Balmer-alpha radiation of first-orbit fast ions after charge exchange with edge neutrals have been measured in the DIII-D tokamak. Several collimated optics systems view the edge region---while avoiding any active beams---and carry light to a spectrometer tuned to the region of the 656.1 nm deuterium-alpha line. Viewing geometry and the high energy of the lost ions produce Doppler shifts, which effectively separate the fast-ion contributions from the bright, cold edge light. Modulation of the fast-ion source allows for time-evolving background subtraction. A model has been developed for the spectra of these first-orbit fast ions. The passive fast-ion D-alpha simulation (P-FIDAsim) is a forward model consisting of an experimentally- validated beam model, an ion orbit-following code, a collisional-radiative model, and a synthetic spectrometer. Eighty-six experimental spectra were obtained using 6 different neutral beam fast-ion sources and 13 different viewing chords. Parameters such as plasma current, toroidal field, electron density, plasma cross-sectional shape, and number of x-points were varied. Uncalibrated experimental spectra have an overall Spearman rank correlation coefficient with the shape of simulated spectra of 0.58 with subsets of cases rising to a correlation of 0.80. A single set of calibrated spectra (shot 152817) was measured and is used to estimate the neutral density throughout the cross-section of the tokamak. This is done by inverting the simulated spectra in order to find the best neutral density (in a least squares sense) required to best match the experimental spectra. The resulting 2D neutral density shows the expected increase toward each x-point. The average neutral density is found to be 3.3 x 105cm -3 a the magnetic axis, 2.3 x 108cm -3 in the core, 8.1 x 109 cm-3 at the plasma boundary, and 1.1 x 10 11cm-3 near the wall. A technique is developed which--after us first-orbit light to calibrate the system--can quantify

  9. Violet spectra of carbon stars associated with silicate features

    NASA Astrophysics Data System (ADS)

    Izumiura, Hideyuki

    2003-04-01

    We have observed the violet spectra of three carbon stars, BM Gem, V778 Cyg, and EU And, that are associated with silicate dust emission features as well as that of a proto-typical J-type carbon star, Y CVn, with the high dispersion spectrograph (HDS) on SUBARU telescope. The spectrum of BM Gem has revealed the presence of Balmer lines up to H23, all of which are found to have P-Cyg type line profile, as well as the Paschen and Balmer continuum emission. The blue-shifted absorption gives the gas outflow velocity of about 400 km s-1, that is very unusual for a cool carbon star. Our results strongly suggest the existence of a low luminosity companion surrounded by an accretion disk in BM Gem system, which have long been postulated but has never been confirmed. We have not detected either continuum or line emission in the violet region shortward of 4000Å in the other two silicate carbon stars.

  10. Extended Pre-Transit Structures and the Exosphere Detected for HD189733b in Optical Hydrogen Balmer Line Absorption

    NASA Astrophysics Data System (ADS)

    Redfield, Seth; Cauley, P. Wilson; Jensen, Adam G.; Barman, Travis; Endl, Michael; Cochran, William

    2015-12-01

    We present two separate observations of HD189733b in the three strongest hydrogen Balmer lines (H-alpha, H-beta, and H-gamma), with HiRES on Keck I that show definitive in-transit absorption, confirming the detection with the HET by Jensen et al. (2012), as well as, significant pre-transit absorption. Recently, pre-transit absorption in UV metal transitions of the hot Jupiter exoplanets HD 189733b and WASP12-b have been interpreted as being caused by material compressed in a planetary bow shock, however our observations are the first to densely time-sample and redundantly detect these extended planetary structures. While our first observations (obtained in 2013 and presented in Cauley et al. 2015), were consistent with a bow shock, our subsequent observation taken in August 2015 show pre-transit absorption but with a pattern that is inconsistent with the 2013 model. Instead, the observations indicate significant variability in the strength and timing of the pre-transit absorption. We also find differences in the strength of the in-transit exospheric absorption as well. These changes could be indicative of variability in the extreme stellar wind properties found at just 8 stellar radii, which could drive the extended atmospheric interaction between star and planet. The pre-transit absorption in 2013 was first observed 65 minutes prior to transit (corresponding to a linear distance of ~7 planetary radii), although it could have started earlier. The pre-transit signal in 2015, which is well sampled, is first detected 165 minutes prior to transit (a linear distance of ~17 planetary radii). The line shape of the pre-transit feature and the shape of the time series absorption provide the strongest constraints on the morphology and physical characteristics of extended structures around the exoplanet. The absorption strength observed in the Balmer lines indicates an optically thick, but physically small, geometry. If part of this extended structure is a bow shock mediated

  11. The ejection of shells in the stellar wind of P CYG - The most plausible explanation of the Balmer-line radial velocity variations

    NASA Astrophysics Data System (ADS)

    Markova, N.

    1986-07-01

    Our new data of the Balmer line radial velocities in the P Cygni spectrum are compared to the measurments published by de Groot (1969), Kolka (1983) and Markova (1986). The observed variations are analysed in terms of a model proposed by Kolka (1983) which implies a multiple ejection of shells in the stellar wind of P Cygni. It is shown that all data agree to an ejection time scale of about 200 days. The estimated accelerations for the three data groups are very close which supposes a stability of the ejection mechanism over an interval of about 40 yr. The radial velocities of nalmer and the FeII and FeIII (far UV) lines are compared. The identity of the Balmer and the FeII and FeIII shells is discussed.

  12. VizieR Online Data Catalog: Balmer break galaxies at z<1.5 star formation (Diaz Tello+, 2016)

    NASA Astrophysics Data System (ADS)

    Diaz Tello, J.; Donzelli, C.; Padilla, N.; Akiyama, M.; Fujishiro, N.; Yoshikawa, T.; Hanami, H.

    2016-05-01

    The galaxies presented in this article come from a sample constructed to study star formation activity of massive galaxies in the redshift range z=0.1-3.0 (Diaz Tello et al., 2013ApJ...771....7D; hereafter D13). The chosen field, the SXDF (RA=02:18:00, DE=-05:00:00; Furusawa et al., 2008, Cat. J/ApJS/176/1) has the advantage that deep photometric data is available in the bands u, B, R, i, z (Subaru), J, H, K (UKIRT), and in all MIR Spitzer bands. The parent sample was selected using the λ3646 Balmer and λ4000 break features as tracers of redshift, as described by Daddi et al. (2004ApJ...617..746D), utilizing the BzK color-color diagram to select star-forming galaxies in a particular redshift range. Furthermore, we used two color-color diagrams to select star-forming galaxies in a lower redshift range than the BzK diagram; these diagrams were presented in Hanami et al. (2012PASJ...64...70H; uVi and uRJ diagrams). (1 data file).

  13. Evaluation of hydrogen atom density in the plasma core region based on the Balmer-α line profile

    NASA Astrophysics Data System (ADS)

    Goto, M.; Sawada, K.; Fujii, K.; Hasuo, M.; Morita, S.

    2011-02-01

    The Balmer-α line profile is measured with high wavelength resolution for a discharge in the Large Helical Device. The line profile is regarded as a superposition of continuously varying Doppler broadened components and is expressed as the Laplace transform. Numerical Laplace inversion of the measured line profile gives the distribution function of line emissivity in terms of atom temperature. The temperature dependence of the line emissivity is interpreted as spatial dependence so that the ionization rate and atom density of neutral hydrogen are determined. The temperature range of the detected atoms extends beyond 2 keV which corresponds to a penetration depth of about 1 m in the plasma, or the location at ρ ~ 0.3, where ρ is the normalized minor radius. The atom density of approximately 1013 m-3 is derived in the plasma core region which is more than four orders smaller than that at the plasma boundary. Calculation of neutral transport with a Monte-Carlo simulation code gives satisfactory consistency with the experimental results.

  14. Numerical and experimental study of atomic transport and Balmer line intensity in Linac4 negative ion source

    SciTech Connect

    Shibata, T. Nishida, K.; Hatayama, A.; Mattei, S.; Lettry, J.

    2015-04-08

    Time structure of Balmer H{sub α} line intensity in Linac4 RF plasma has been analyzed by the combined simulation model of atomic transport and Collisional-Radiative models. As a preliminary result, time variation of the line intensity in the ignition phase of RF plasma is calculated and compared with the experimental results by photometry. For the comparison, spatial distribution of the local H{sub α} photon emission rate at each time is calculated from the numerical model. The contribution of the local photon emission rates to the observed line intensity via optical viewing port is also investigated by application of the mock-up of the optical viewing port and the known light source. It has been clarified from the analyses that the higher and the lower peaks of the H{sub α} line intensity observed during 1 RF cycle is mainly due to the different spatial distributions in the electron energy distribution function and the resultant local photon emission rate. These results support previous suggestion that the existence of the capacitive electric field in axial direction leads to the higher/lower peaks of the line intensity.

  15. EFFECTS OF AN ACCRETION DISK WIND ON THE PROFILE OF THE BALMER EMISSION LINES FROM ACTIVE GALACTIC NUCLEI

    SciTech Connect

    Flohic, Helene M. L. G.; Eracleous, Michael; Bogdanovic, Tamara E-mail: mce@astro.psu.edu

    2012-07-10

    We explore the connection between active galactic nuclei (AGNs) with single- and double-peaked broad Balmer emission lines by using models dealing with radiative transfer effects through a disk wind. Our primary goal is to assess the applicability of the Murray and Chiang model by making an extensive and systematic comparison of the model predictions with data. In the process, we also verify the original derivation and evaluate the importance of general relativistic effects. As the optical depth through the emission layer increases, the peaks of a double-peaked profile move closer and eventually merge, producing a single peak. The properties of the emission line profile depend as sensitively on the geometric parameters of the line-emitting portion of the disk as they do on the disk-wind parameters. Using a parameter range that encompasses the expected characteristics of the broad-line regions in AGNs, we construct a database of model profiles and measure a set of diagnostic properties. Comparisons of the model profiles with emission lines from a subset of Sloan digital Sky Survey quasars show that observed lines are consistent with moderately large optical depth in the disk wind and a range of disk inclinations i {approx}< 45 Degree-Sign . Including relativistic effects is necessary to produce the asymmetries of observed line profiles.

  16. Doppler spectroscopy of hydrogen Balmer lines in a hollow cathode glow discharge in ammonia and argon-ammonia mixture

    SciTech Connect

    Sisovic, N. M.; Konjevic, N.

    2008-11-15

    The results of Doppler spectroscopy of hydrogen Balmer lines from a stainless steel (SS) and copper (Cu) hollow cathode (HC) glow discharge in ammonia and argon-ammonia mixture are reported. The experimental profiles in ammonia discharge are fitted well by superposing three Gaussian profiles. The half widths, in energy units, of narrow and medium Gaussians are in the ranges 0.3-0.4 eV and 3-4 eV, respectively, for both hollow cathodes what is expected on the basis of earlier electron beam{yields}NH{sub 3} experiments. The half widths of the largest Gaussian in ammonia are 46 and 55 eV for SS and Cu HC, respectively. In argon-ammonia discharge, three Gaussians are also required to fit experimental profiles. While half widths of narrow and medium Gaussians are similar to those in ammonia, the half widths of the largest Gaussians are 35 and 42 eV for SS and Cu HC, respectively. The half widths of the largest Gaussians in ammonia and in argon-ammonia mixture indicate the presence of excessive Doppler broadening.

  17. Measurements of neutral density profiles using a deuterium Balmer-alpha diagnostic in the C-2 FRC plasma

    SciTech Connect

    Gupta, Deepak K.; Deng, B. H.; Knapp, K.; Sun, X.; Thompson, M. C.

    2012-10-15

    In C-2 field-reversed configuration (FRC) device, low neutral density outside the FRC separatrix is required to minimize the charge exchange loss of fast particles. Titanium gettering is used in C-2 to reduce the wall recycling and keep the neutral density low in plasma edge. The measurements of neutral density radial profile are desirable to understand the plasma recycling and the effects of titanium gettering. These measurements are also needed to study the interaction of neutral beams with FRC plasma and confinement of fast ions. Diagnostic based on absolute deuterium Balmer-alpha (D-alpha) radiation measurements is developed and deployed on C-2 device to measure the radial profile of neutral density. Simultaneous measurements of electron density and temperature are done using CO{sub 2} interferometer, Thomson scattering, and triple probes diagnostics along with absolute D-alpha radiation. Abel inversion was performed to get the time dependent radial profile of the local D-alpha emission density. Neutral density profiles are obtained under different machine conditions of titanium deposition.

  18. Are Boltzmann plots of hydrogen Balmer lines a tool for identifying a subclass of S1 AGN?

    NASA Astrophysics Data System (ADS)

    Rafanelli, P.; Ciroi, S.; Cracco, V.; Di Mille, F.; Ilić, D.; La Mura, G.; Popović, L. Č.

    2014-10-01

    It is becoming clear that we can define two different types of nearby AGN belonging to the Seyfert 1 class (S1), on the basis of the match of the intensities of their Broad Balmer Lines (BBL) with the Boltzmann Plots (BP). These two types of S1 galaxies, that we call BP-S1 and NoBP-S1, are characterized, in first approximation, by Broad Line Regions (BLR) with different structural and physical properties. In this communication, we show that these features can be well pointed out by a multi-wavelength analysis of the continuum and of the broad recombination Hydrogen lines, that we carry out on a sample of objects detected at optical and X-ray frequencies. The investigation is addressed to verify whether BP-S1 are the ideal candidates for the study of the kinematical and structural properties of the BLR, in order to derive reliable estimates of the mass of their central engine and to constrain the properties of their nuclear continuum spectrum.

  19. Effective temperature of A and F stars from Balmer line profiles, and the Infrared Flux Method. I. Two AM stars: the Sun and Procyon as standards.

    NASA Astrophysics Data System (ADS)

    van't Veer-Menneret, C.; Megessier, C.

    1996-05-01

    With a view of improving the effective temperature determinations, two independent methods have been used, Balmer line profile fitting and the Infrared Flux Method. The effective temperature is the first fundamental parameter to be established before doing abundance analyses of Am stars. For this purpose we used new CCD observations, and the latest versions of Kurucz codes for stellar atmospheres and Balmer line profile calculations. We used the Balmer line profile property of being gravity independent for effective temperatures less than 8500K. However examination of ATLAS9 and BALMER9 code results show that Balmer line profiles are not only dependent on the effective temperature of the atmosphere, but also on its metallicity, and are moreover strongly sensitive to its structure. In a first step we adjusted the convection parameter of atmospheres of the Sun, whose T_eff_, gravity and metallicity are well and independently established, and of Procyon used as a standard for hotter stars. The results showed that in order to fit the observed profiles, unless we increase the temperature of the Sun and Procyon by 400K, we had to lower the mixing length parameter l/H_p_ to 0.5, and to remove the overshooting option in ATLAS9 code, showing in this way a large effect of this process on computed profiles. We recomputed the models with these new options, and adopted for the two Am stars 63 Tauri and τ UMa the parameters [M/H]=+0.5 and logg=4.0 as the most reasonable working hypotheses. Concerning the Infrared Flux Method, it had to be used in its modified form, to take into account the presence of a companion, since both Am stars are single lined spectroscopic binaries. It turned out that the agreement between the effective temperatures derived independently by the two methods was very good. We combined the effective temperatures obtained from the two methods, which yielded T_eff_=7190K for 63 Tauri, and T_eff_=7045K for τ UMa, with the remarkably low internal uncertainty

  20. Spatially Resolved Spectroscopy of a Balmer-dominated Shock in the Cygnus Loop: An Extremely Thin Cosmic-Ray Precursor?

    NASA Astrophysics Data System (ADS)

    Katsuda, Satoru; Maeda, Keiichi; Ohira, Yutaka; Yatsu, Yoichi; Mori, Koji; Aoki, Wako; Morihana, Kumiko; Raymond, John C.; Ghavamian, Parviz; Lee, Jae-Joon; Shimoda, Jiro; Yamazaki, Ryo

    2016-03-01

    We present high-resolution long-slit spectroscopy of a Balmer-dominated shock in the northeastern limb of the Cygnus Loop with the Subaru high dispersion spectrograph. By setting the slit angle along the shock normal, we investigate variations of the flux and profile of the Hα line from preshock to postshock regions with a spatial resolution of ˜4 × 1015 cm. The Hα line profile can be represented by a narrow (28.9 ± 0.7 km s-1) Gaussian in a diffuse region ahead of the shock, i.e., a photoionization precursor, and narrow (33.1 ± 0.2 km s-1) plus broad (130-230 km s-1) Gaussians at the shock itself. We find that the width of the narrow component abruptly increases up to 33.1 ± 0.2 km s-1, or 38.8 ± 0.4 km s-1 if we eliminate projected emission originating from the photoionization precursor, in an unresolved thin layer (≲4 × 1015 cm at a distance of 540 pc) at the shock. We show that the sudden broadening can be best explained by heating via damping of Alfvén waves in a thin cosmic-ray (CR) precursor, although other possibilities are not fully ruled out. The thickness of the CR precursor in the Cygnus Loop (a soft gamma-ray emitter) is an order of magnitude thinner than that in Tycho’s Knot g (a hard gamma-ray emitter), which may be caused by the different energy distribution of accelerated particles between the two sources. In this context, systematic studies might reveal a positive correlation between the thickness of the CR precursor and the hardness of the CR energy distribution.

  1. Storm Spectra

    NASA Technical Reports Server (NTRS)

    2007-01-01

    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.

  2. On the role of atomic metastability in the production of Balmer line radiation from ‘cold’ atomic hydrogen, deuterium and hydrogenic ion impurities in fusion edge plasmas

    NASA Astrophysics Data System (ADS)

    Hey, J. D.

    2012-03-01

    Published arguments, which assign an important role to atomic metastability in the production of ‘narrow’ Zeeman component radiation from the boundary region of fusion plasmas, are examined critically in relation to l-redistribution by proton and electron collisions, and mixing of unperturbed atomic states by the ion microfield and microfield gradient. It is concluded that these important processes indeed severely constrain the contribution from ‘metastable’ states to the generation of the hydrogen Balmer spectra, for electron concentrations above 1012 cm-3, as pointed out before by the present author (Hey et al 1999 J. Phys. B: At. Mol. Opt. Phys. 32 3555). The analysis of collision-induced l-redistribution represents an extension of that used previously (Hey et al 1996 Contrib. Plasma Phys. 36 583), applicable up to higher electron densities. For comparison purposes, we also consider the question of metastability of ionized helium in a low-temperature plasma, and that of some common hydrogenic impurities (C5+ and Ne9+) in a hydrogen (deuterium) fusion plasma. While for low nuclear charge Z the metastability of 2s1/2 levels is quenched by the plasma environment, it is much reduced in high-Z ions owing to the rapid increase with Z of the two-photon electric dipole (2E1) and magnetic dipole (M1) spontaneous transition rates to the ground state, whereas the role of the plasma in these cases is less important. The main new principle elaborated in this work is the sensitivity of atomic line strengths, and hence collision strengths, to perturbation by the plasma environment for transitions between fine-structure sublevels of the same principal quantum number. As the plasma microfield strength grows, ‘allowed’ transitions diminish in strength, while ‘forbidden’ transitions grow. However, owing to violation of the parity selection rule, there is an overall loss of collision strength available to transitions, resulting from the appearance of significant

  3. Vanadium Oxide in the Spectra of Mira Variables

    NASA Astrophysics Data System (ADS)

    Castelaz, M. W.; Luttermoser, D. G.; Piontek, R. A.

    1999-05-01

    Over the last three years, we have made spectroscopic measurements of twenty Mira variable stars, as a function of phase, probing their stellar atmospheres and underlying pulsation mechanisms. Measurement of variations in TiO and VO with phase can be used to help determine whether these molecular species are produced in an extended region above the layers where Balmer line emission occurs or below this shocked region. Piontek & Luttermoser (1999 IAPPPC, submitted), produce synthetic spectra for three Mira variables, R Leo, V CVn, and R CVn as a function of phase. Comparison of their synthetic spectra to our observed spectra yield the fundamental astrophysical parameters of effective temperatures and surface gravities. Spectra are synthesized with LTE stellar stmospheres code ATLAS, using the 6.6--million Indiana University atomic and molecular line dataset. Piontek & Luttermoser point out that the IU dataset does not include vanadium oxide (VO). Thus, there is a noticeable difference between the synthetic spectra and observed near-IR spectra corresponding to the B-X bands of VO (Mahanti 1935, Proc. Phys. Soc., 47, 43; Keenan & Schroeder 1952,L. W., ApJ, 115, 82). In order to incorporate the VO bands in the synthetic spectra, we need to establish tables of wavenumbers, lowest energy levels, and oscillator strengths. Producing the tables is non-trivial. Laboratory measurements of wavenumbers are used in the Just-Overlapping Line Approximation (JOLA; Tsuji 1966, PASJ, 18, 127) to calculate oscillator strengths. The JOLA technique and preliminary results will be presented. MWC greatly appreciates support from the National Science Foundation grant AST-9500756. RAP acknowledges the Southeastern Association for Research in Astronomy 1998 Summer REU program supported by the National Science Foundation and thanks DGL for being his mentor.

  4. TIME-RESOLVED PROPERTIES AND GLOBAL TRENDS IN dMe FLARES FROM SIMULTANEOUS PHOTOMETRY AND SPECTRA

    SciTech Connect

    Kowalski, Adam F.; Hawley, Suzanne L.; Davenport, James R. A.; Wisniewski, John P.; Osten, Rachel A.; Hilton, Eric J.; Holtzman, Jon A.; Schmidt, Sarah J.

    2013-07-15

    We present a homogeneous analysis of line and continuum emission from simultaneous high-cadence spectra and photometry covering near-ultraviolet and optical wavelengths for 20 M dwarf flares. These data were obtained to study the white-light continuum components at bluer and redder wavelengths than the Balmer jump. Our goals were to break the degeneracy between emission mechanisms that have been fit to broadband colors of flares and to provide constraints for radiative-hydrodynamic (RHD) flare models that seek to reproduce the white-light flare emission. The main results from the analysis are the following: (1) the detection of Balmer continuum (in emission) that is present during all flares and with a wide range of relative contributions to the continuum flux at bluer wavelengths than the Balmer jump; (2) a blue continuum at flare maximum that is linearly decreasing with wavelength from {lambda} = 4000-4800 A, indicative of hot, blackbody emission with typical temperatures of T{sub BB} {approx} 9000-14, 000 K; (3) a redder continuum apparent at wavelengths longer than H{beta} ({lambda} {approx}> 4900 A) which becomes relatively more important to the energy budget during the late gradual phase. The hot blackbody component and redder continuum component have been detected in previous studies of flares. However, we have found that although the hot blackbody emission component is relatively well-represented by a featureless, single-temperature Planck function, this component includes absorption features and has a continuum shape strikingly similar to the spectrum of an A-type star as directly observed in our flare spectra. New model constraints are presented for the time evolution among the hydrogen Balmer lines and between Ca II K and the blackbody continuum emission. We calculate Balmer jump flux ratios and compare to the solar-type flare heating predictions from RHD models. The model ratios are too large and the blue-optical ({lambda} = 4000-4800 A) slopes are too

  5. PHYSICAL PROPERTIES, STAR FORMATION, AND ACTIVE GALACTIC NUCLEUS ACTIVITY IN BALMER BREAK GALAXIES AT 0 < z < 1

    SciTech Connect

    Diaz Tello, J.; Donzelli, C.; Padilla, N.; Fujishiro, N.; Yoshikawa, T.; Hanami, H.; Hatsukade, B.

    2013-07-01

    We present a spectroscopic study with the derivation of the physical properties of 37 Balmer break galaxies, which have the necessary lines to locate them in star-forming-active galactic nuclei (AGNs) diagnostic diagrams. These galaxies span a redshift range from 0.045 to 0.93 and are somewhat less massive than similar samples of previous works. The studied sample has multiwavelength photometric data coverage from the ultraviolet to mid-infrared (MIR) Spitzer bands. We investigate the connection between star formation and AGN activity via optical, mass-excitation (MEx), and MIR diagnostic diagrams. Through optical diagrams, 31 (84%) star-forming galaxies, two (5%) composite galaxies, and three (8%) AGNs were classified, whereas from the MEx diagram only one galaxy was classified as AGN. A total of 19 galaxies have photometry available in all the IRAC/Spitzer bands. Of these, three AGN candidates were not classified as AGN in the optical diagrams, suggesting they are dusty/obscured AGNs, or that nuclear star formation has diluted their contributions. By fitting the spectral energy distribution of the galaxies, we derived the stellar masses, dust reddening E(B - V), ages, and UV star formation rates (SFRs). Furthermore, the relationship between SFR surface density ({Sigma}{sub SFR}) and stellar mass surface density per time unit ({Sigma}{sub M{sub */{tau}}}) as a function of redshift was investigated using the [O II] {lambda}3727, 3729, H{alpha} {lambda}6563 luminosities, which revealed that both quantities are larger for higher redshift galaxies. We also studied the SFR and specific SFR (SSFR) versus stellar mass and color relations, with the more massive galaxies having higher SFR values but lower SSFR values than less massive galaxies. These results are consistent with previous ones showing that, at a given mass, high-redshift galaxies have on average larger SFR and SSFR values than low-redshift galaxies. Finally, bluer galaxies have larger SSFR values than redder

  6. DUST EXTINCTION FROM BALMER DECREMENTS OF STAR-FORMING GALAXIES AT 0.75 {<=} z {<=} 1.5 WITH HUBBLE SPACE TELESCOPE/WIDE-FIELD-CAMERA 3 SPECTROSCOPY FROM THE WFC3 INFRARED SPECTROSCOPIC PARALLEL SURVEY

    SciTech Connect

    Dominguez, A.; Siana, B.; Masters, D.; Henry, A. L.; Martin, C. L.; Scarlata, C.; Bedregal, A. G.; Malkan, M.; Ross, N. R.; Atek, H.; Colbert, J. W.; Teplitz, H. I.; Rafelski, M.; McCarthy, P.; Hathi, N. P.; Dressler, A.; Bunker, A.

    2013-02-15

    Spectroscopic observations of H{alpha} and H{beta} emission lines of 128 star-forming galaxies in the redshift range 0.75 {<=} z {<=} 1.5 are presented. These data were taken with slitless spectroscopy using the G102 and G141 grisms of the Wide-Field-Camera 3 (WFC3) on board the Hubble Space Telescope as part of the WFC3 Infrared Spectroscopic Parallel survey. Interstellar dust extinction is measured from stacked spectra that cover the Balmer decrement (H{alpha}/H{beta}). We present dust extinction as a function of H{alpha} luminosity (down to 3 Multiplication-Sign 10{sup 41} erg s{sup -1}), galaxy stellar mass (reaching 4 Multiplication-Sign 10{sup 8} M {sub Sun }), and rest-frame H{alpha} equivalent width. The faintest galaxies are two times fainter in H{alpha} luminosity than galaxies previously studied at z {approx} 1.5. An evolution is observed where galaxies of the same H{alpha} luminosity have lower extinction at higher redshifts, whereas no evolution is found within our error bars with stellar mass. The lower H{alpha} luminosity galaxies in our sample are found to be consistent with no dust extinction. We find an anti-correlation of the [O III] {lambda}5007/H{alpha} flux ratio as a function of luminosity where galaxies with L {sub H{alpha}} < 5 Multiplication-Sign 10{sup 41} erg s{sup -1} are brighter in [O III] {lambda}5007 than H{alpha}. This trend is evident even after extinction correction, suggesting that the increased [O III] {lambda}5007/H{alpha} ratio in low-luminosity galaxies is likely due to lower metallicity and/or higher ionization parameters.

  7. Time resolved EUV spectra from Zpinching capillary discharge plasma

    NASA Astrophysics Data System (ADS)

    Jancarek, Alexandr; Nevrkla, Michal; Nawaz, Fahad

    2015-09-01

    We developed symmetrically charged driver to obtain high voltage, high current Z-pinching capillary discharge. Plasma is created by up to 70 kA, 29 ns risetime current pulse passing through a 5 mm inner diameter, 224 mm long capillary filled with gas to initial pressure in the range of 1 kPa. Due to the low inductance design of the driver, the pinch is observable directly from the measured current curve. Time-integrated and time-resolved spectra of discharge plasma radiation are recorded together with the capillary current and analyzed. The most encouraging spectra were captured in the wavelength range 8.3 ÷ 14 nm. This spectral region contains nitrogen Balmer series lines including potentially lasing NVII 2 - 3 transition. Spectral lines are identified in the NIST database using the FLY kinetic code. The line of 13.38 nm wavelength, transition NVII 2 - 3, was observed in gated, and also in time-integrated spectra for currents >60 kA. This work has been supported by the Ministry of Education, Youth and Sports of the Czech Republic grants LG13029.

  8. Correlations between density distributions, optical spectra, and ion species in a hydrogen plasma (invited)

    NASA Astrophysics Data System (ADS)

    Cortázar, O. D.; Megía-Macías, A.; Tarvainen, O.; Kalvas, T.; Koivisto, H.

    2016-02-01

    An experimental study of plasma distributions in a 2.45 GHz hydrogen discharge operated at 100 Hz repetition rate is presented. Ultrafast photography, time integrated visible light emission spectra, time resolved Balmer-alpha emission, time resolved Fulcher Band emission, ion species mass spectra, and time resolved ion species fraction measurements have been implemented as diagnostic tools in a broad range of plasma conditions. Results of plasma distributions and optical emissions correlated with H+, H2 + , and H3 + ion currents by using a Wien filter system with optical observation capability are reported. The magnetic field distribution and strength is found as the most critical factor for transitions between different plasma patterns and ion populations.

  9. Correlations between density distributions, optical spectra, and ion species in a hydrogen plasma (invited).

    PubMed

    Cortázar, O D; Megía-Macías, A; Tarvainen, O; Kalvas, T; Koivisto, H

    2016-02-01

    An experimental study of plasma distributions in a 2.45 GHz hydrogen discharge operated at 100 Hz repetition rate is presented. Ultrafast photography, time integrated visible light emission spectra, time resolved Balmer-alpha emission, time resolved Fulcher Band emission, ion species mass spectra, and time resolved ion species fraction measurements have been implemented as diagnostic tools in a broad range of plasma conditions. Results of plasma distributions and optical emissions correlated with H(+), H2 (+), and H3 (+) ion currents by using a Wien filter system with optical observation capability are reported. The magnetic field distribution and strength is found as the most critical factor for transitions between different plasma patterns and ion populations. PMID:26931922

  10. The continuum emission spectrum of Hf 2-2 near the Balmer limit and the ORL versus CEL abundance and temperature discrepancy

    NASA Astrophysics Data System (ADS)

    Storey, P. J.; Sochi, Taha

    2014-05-01

    The continuum spectrum of the planetary nebula Hf 2-2 close to the Balmer discontinuity is modelled in the context of the long-standing problem of the abundance and temperature discrepancy found when analysing optical recombination lines and collisionally excited forbidden lines in nebulae. Models are constructed using single and double Maxwell-Boltzmann distributions as well as κ-distributions for the energies of the free electrons. New results for the necessary continuum and line emission coefficients are presented calculated with κ-distributed energies. The best fit to the observed continuum spectrum is found to be a model comprising two components with dramatically different temperatures and with a Maxwell-Boltzmann distribution of electron energies. On the basis of a χ2 analysis, this model is strongly favoured over a model with κ-distributed electron energies.

  11. Asymmetry of the Balmer-alpha line shape and recovery of the effective hydrogen temperature in the tokamak scrape-off layer

    SciTech Connect

    Neverov, V. S. Kukushkin, A. B.; Lisgo, S. W. Kukushkin, A. S.; Alekseev, A. G.

    2015-02-15

    An algorithm for recovering the effective temperature of atoms of hydrogen (and its isotopes) in the tokamak scrape-off layer from the asymmetry of the Balmer-alpha line shape is proposed. The algorithm is based on the parametrization of the asymmetry of the line shape caused by the nonlocal character of neutral hydrogen flux from the wall into the tokamak plasma. The accuracy of the algorithm is tested against the results of simulations of the velocity distribution function of deuterium neutrals in the scrape-off layer by the EIRENE code with the use of the source data on the main plasma component in the quasi-stationary stage of the inductive mode of ITER operation calculated by the SOLPS4.3 (B2-EIRENE) code.

  12. 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)

  13. [The radial velocity measurement accuracy of different spectral type low resolution stellar spectra at different signal-to-noise ratio].

    PubMed

    Wang, Feng-Fei; Luo, A-Li; Zhao, Yong-Heng

    2014-02-01

    The radial velocity of the star is very important for the study of the dynamics structure and chemistry evolution of the Milky Way, is also an useful tool for looking for variable or special objects. In the present work, we focus on calculating the radial velocity of different spectral types of low-resolution stellar spectra by adopting a template matching method, so as to provide effective and reliable reference to the different aspects of scientific research We choose high signal-to-noise ratio (SNR) spectra of different spectral type stellar from the Sloan Digital Sky Survey (SDSS), and add different noise to simulate the stellar spectra with different SNR. Then we obtain theradial velocity measurement accuracy of different spectral type stellar spectra at different SNR by employing a template matching method. Meanwhile, the radial velocity measurement accuracy of white dwarf stars is analyzed as well. We concluded that the accuracy of radial velocity measurements of early-type stars is much higher than late-type ones. For example, the 1-sigma standard error of radial velocity measurements of A-type stars is 5-8 times as large as K-type and M-type stars. We discuss the reason and suggest that the very narrow lines of late-type stars ensure the accuracy of measurement of radial velocities, while the early-type stars with very wide Balmer lines, such as A-type stars, become sensitive to noise and obtain low accuracy of radial velocities. For the spectra of white dwarfs stars, the standard error of radial velocity measurement could be over 50 km x s(-1) because of their extremely wide Balmer lines. The above conclusion will provide a good reference for stellar scientific study. PMID:24822441

  14. The Spectra of Mira Variable Stars.

    NASA Astrophysics Data System (ADS)

    Crowe, Richard Alan

    The catalog of Keenan, Garrison and Deutsch (1974) has been extended by the addition of 483 blue spectrograms of 72 Southern Hemisphere Mira variables. About 190 direct and image-tube plates at a dispersion of 120 (ANGSTROM)/mm were obtained in Chile between 1977 and 1982. Spectral types, emission-line ratios for H(delta) 4101/H(gamma) 4340/H(beta) 4861 and eye-estimated intensities of the absorption lines Ca I (lamda)4226, Cr I (lamda)4254 and Sr II (lamda)4077 have been tabulated. Spectral montages for six stars are used to illustrate changes in the visual spectra of Mira variables through their respective cycles. Radial velocities of absorption and emission line systems have been determined for 22 Northern Hemisphere Mira variables. These were measured from approximately 65 spectra obtained on baked IIa-O plates at a dispersion of 12 (ANGSTROM)/mm with the DDO 1.88-m telescope. Most of these Northern Hemisphere stars were observed close to maximum light, and so only in a few cases (for example, R Trianguli) is there any useful phase information available. It can be shown from this data that the irregular behaviour of absorption features in Mira variables is the consequence of a second shock front which is higher up in the atmosphere than the one producing Balmer emission, as has been proposed by Hill and Willson, 1979b). We present evidence that strong emission is associated with weak-line cycles (when overlying TiO absorption is also weaker) and that the velocity gradient is directly responsible for the weakening by the escape enhancement process (Mihalas, 1978). Since the shock strength varies from cycle to cycle, we do not expect the affected lines to maintain the same equivalent width at the same phase in different cycles. There is, however, a great deal of internal scatter from star to star which confuses the interpretation. The separation of Mira variables into two groups (namely, those with spectral types earlier and later than M5e at maximum light) helps

  15. Photographic spectra of fireballs

    NASA Astrophysics Data System (ADS)

    Borovička, J.

    2016-01-01

    Two methods of spectroscopy of meteors using image intensified video cameras and classical photographic film cameras are compared. Video cameras provide large number of low resolution spectra of meteors of normal brightness, which can be used for statistical studies. Large format film cameras have been used through the history and provide high resolution spectra, which can be used to derive temperature, density and absolute abundances of various elements in the radiating plasma. The sensitivity of films is, however, low and only spectra of bright meteors (fireballs) can be studied. Examples of photographic fireball spectra are provided.

  16. 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.

  17. Application of Artificial Neural Network to the Classification of Stellar Spectra

    NASA Astrophysics Data System (ADS)

    Zaric, D.

    2009-09-01

    The application of an artificial neural network (ANN) based on a multi-layered back-propagation algorithm to the classification of stellar spectra is presented. Using a part of catalogue's data in the training process, network learns to pssociate the appearance of a visual spectrum (hydrogen Balmer lines, continuum shape) with the classification parameters (MK spectral types). The performance of the network is evaluatey by using it to classihy phe remaining rata set and by comparing this ANN classification with the original catalogue one. ANN code is written in C++. It uses back-propagation algorithm for training and an approach that can be best described as "associative memory model" for prediction (classification).

  18. Objective identification of informative wavelength regions in galaxy spectra

    SciTech Connect

    Yip, Ching-Wa; Szalay, Alexander S.; Budavári, Tamás; Wyse, Rosemary F. G.; Mahoney, Michael W.; Csabai, István; Dobos, Laszlo E-mail: szalay@jhu.edu

    2014-05-01

    Understanding the diversity in spectra is the key to determining the physical parameters of galaxies. The optical spectra of galaxies are highly convoluted with continuum and lines that are potentially sensitive to different physical parameters. Defining the wavelength regions of interest is therefore an important question. In this work, we identify informative wavelength regions in a single-burst stellar population model using the CUR Matrix Decomposition. Simulating the Lick/IDS spectrograph configuration, we recover the widely used D {sub n}(4000), Hβ, and Hδ {sub A} to be most informative. Simulating the Sloan Digital Sky Survey spectrograph configuration with a wavelength range 3450-8350 Å and a model-limited spectral resolution of 3 Å, the most informative regions are: first region—the 4000 Å break and the Hδ line; second region—the Fe-like indices; third region—the Hβ line; and fourth region—the G band and the Hγ line. A principal component analysis on the first region shows that the first eigenspectrum tells primarily the stellar age, the second eigenspectrum is related to the age-metallicity degeneracy, and the third eigenspectrum shows an anti-correlation between the strengths of the Balmer and the Ca K and H absorptions. The regions can be used to determine the stellar age and metallicity in early-type galaxies that have solar abundance ratios, no dust, and a single-burst star formation history. The region identification method can be applied to any set of spectra of the user's interest, so that we eliminate the need for a common, fixed-resolution index system. We discuss future directions in extending the current analysis to late-type galaxies. ASCII formatted tables of the regional eigenspectra are available.

  19. Action spectra again?

    PubMed

    Coohill, T P

    1991-11-01

    Action spectroscopy has a long history and is of central importance to photobiological studies. Action spectra were among the first assays to point to chlorophyll as the molecule most responsible for plant growth and to DNA as the genetic material. It is useful to construct action spectra early in the investigation of new areas of photobiological research in an attempt to determine the wavelength limits of the radiation region causing the studied response. But due to the severe absorption of ultraviolet (UV) radiation by biological samples, UV action spectra were first limited to small cells (bacteria and fungi). Advances in techniques (e.g. single cell culture) and analysis allowed accurate action spectra to be reported even for mammalian cells. But precise analytical action spectra are often difficult to obtain when large, pigmented, or groups of cells are investigated. Here some action spectra are limited in interpretation and merely supply a wavelength vs effect curve. When polychromatic sources are employed, the interpretation of action spectra is even more complex and formidable. But such polychromatic action spectra can be more directly related to ambient responses. Since precise action spectra usually require the completion of a relatively large number of careful experiments using somewhat sophisticated equipment over a range of at least six wavelengths, they are often not pursued. But they remain central to the elucidation of the effect being studied. The worldwide community has agreed that stratospheric ozone is depleting, with the possibility of a consequent rise in the amount of UV-B (290-320 nm) reaching the earth's surface. It is therefore essential that new action spectra be completed for UV-B effects on a large variety of responses of human, animal, and aquatic plant systems. Combining these action spectra with the known amounts of UV-B reaching the biosphere can give rise to solar UV effectiveness spectra that, in turn, can give rise to estimates

  20. Hydrogen Balmer α line behavior in Laser-Induced Breakdown Spectroscopy depth scans of Au, Cu, Mn, Pb targets in air

    NASA Astrophysics Data System (ADS)

    Senesi, G. S.; Benedetti, P. A.; Cristoforetti, G.; Legnaioli, S.; Palleschi, V.

    2010-07-01

    The behavior of hydrogen spectral emission of the plasmas obtained by Laser-Induced Breakdown Spectroscopy (LIBS) measurement of four metal targets (Au, Cu, Mn, Pb) in air was investigated. The plasma was produced by a pulsed Nd:YAG laser emitting in the fundamental wavelength. A systematic study of the spatial-integrated plasma emission obtained by an in-depth scanning of the target was performed for each metal, both in single pulse and collinear double-pulse configurations. Further, a spatial-resolved analysis of the emission of plasma produced on the Al target by a single laser pulse was performed, in order to describe the spatial distribution of emitters deriving from the target and air elements. The line intensities of the main plasma components (target metal, nitrogen, oxygen and hydrogen) were measured in both experimental conditions. Results show that the hydrogen line intensity varies greatly as a function of the metal considered, and exhibits a marked decrease after the first laser shots. However, differently from emission lines due to surface impurities, the hydrogen line intensity reaches a constant level deep inside the target. The spatial-resolved measurements indicate that hydrogen atoms in the plasma mainly derive from the target surface and, only at a minor extent, from the dissociation of molecular hydrogen present in the surrounding air. These findings show that the calculation of plasma electron number density through the measurement of the Stark broadening of hydrogen Balmer α line is possible also in depth scanning measurements.

  1. Thermodynamic analysis of spectra

    SciTech Connect

    Mitchell, G. E.; Shriner, J. F. Jr.

    2008-04-04

    Although random matrix theory had its initial application to neutron resonances, there is a relative scarcity of suitable nuclear data. The primary reason for this is the sensitivity of the standard measures used to evaluate spectra--the spectra must be essential pure (no state with a different symmetry) and complete (no states missing). Additional measures that are less sensitive to these experimental limitations are of significant value. The standard measure for long range order is the {delta}{sub 3} statistic. In the original paper that introduced this statistic, Dyson and Mehta also attempted to evaluate spectra with thermodynamic variables obtained from the circular orthogonal ensemble. We consider the thermodynamic 'internal energy' and evaluate its sensitivity to experimental limitations such as missing and spurious levels. Monte Carlo simulations suggest that the internal energy is less sensitive to mistakes than is {delta}{sub 3}, and thus the internal energy can serve as a addition to the tool kit for evaluating experimental spectra.

  2. The MOSDEF Survey: Measurements of Balmer Decrements and the Dust Attenuation Curve at Redshifts z ~ 1.4–2.6

    NASA Astrophysics Data System (ADS)

    Reddy, Naveen A.; Kriek, Mariska; Shapley, Alice E.; Freeman, William R.; Siana, Brian; Coil, Alison L.; Mobasher, Bahram; Price, Sedona H.; Sanders, Ryan L.; Shivaei, Irene

    2015-06-01

    We present results on the dust attenuation curve of z ∼ 2 galaxies using early observations from the MOSFIRE Deep Evolution Field survey. Our sample consists of 224 star-forming galaxies with zspec = 1.36–2.59 and high signal-to-noise ratio measurements of Hα and Hβ obtained with Keck/MOSFIRE. We construct composite spectral energy distributions (SEDs) of galaxies in bins of Balmer decrement to measure the attenuation curve. We find a curve that is similar to the SMC extinction curve at λ ≳ 2500 Å. At shorter wavelengths, the shape is identical to that of the Calzetti et al. relation, but with a lower normalization. Hence, the new attenuation curve results in star formation rates (SFRs) that are ≈ 20% lower, and stellar masses that are {Δ }{log}({M}*{/M}ȯ )≃ 0.16 dex lower, than those obtained with the Calzetti relation. We find that the difference in the total attenuation of the ionized gas and stellar continuum correlates strongly with SFR, such that for dust-corrected SFRs ≳ 20 M⊙ yr‑1, assuming a Chabrier initial mass function, the nebular emission lines suffer an increasing degree of obscuration relative to the continuum. A simple model that can account for these trends is one in which the UV through optical stellar continuum is dominated by a population of less-reddened stars, while the nebular line and bolometric luminosities become increasingly dominated by dustier stellar populations for galaxies with large SFRs, as a result of the increased dust enrichment that accompanies such galaxies. Consequently, UV- and SED-based SFRs may underestimate the total SFR at even modest levels of ≈20 M⊙ yr‑1. Based on data obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA, and was made possible by the generous financial support of the W.M. Keck Foundation.

  3. 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.

  4. Stars and their Spectra

    NASA Astrophysics Data System (ADS)

    Kaler, James B.

    1997-03-01

    This unique and informative text describes how stars are classified according to their spectral qualities and temperature. James Kaler explains the alphabet of stellar astronomy, running from cool M stars to hot O stars, and tells the story of their evolution. Before embarking on a voyage of cosmic discovery, the author discusses the fundamental properties of stars, their atomic structure and the formation of spectra. Then, Kaler considers each star type individually and explores its spectra in detail. A review of unusual, hard-to-classify stars, and a discussion of data related to the birth, life and death of stars round out the text. This book is an important resource for all amateur astronomers and students of astronomy. Professionals will find it a refreshing read as well.

  5. Parmeterization of spectra

    NASA Technical Reports Server (NTRS)

    Cornish, C. R.

    1983-01-01

    Following reception and analog to digital conversion (A/D) conversion, atmospheric radar backscatter echoes need to be processed so as to obtain desired information about atmospheric processes and to eliminate or minimize contaminating contributions from other sources. Various signal processing techniques have been implemented at mesosphere-stratosphere-troposphere (MST) radar facilities to estimate parameters of interest from received spectra. Such estimation techniques need to be both accurate and sufficiently efficient to be within the capabilities of the particular data-processing system. The various techniques used to parameterize the spectra of received signals are reviewed herein. Noise estimation, electromagnetic interference, data smoothing, correlation, and the Doppler effect are among the specific points addressed.

  6. Barnacle Bill Spectra

    NASA Technical Reports Server (NTRS)

    1997-01-01

    These IMP spectra show the characteristics of the rock surface measured by the Alpha Proton X-Ray Spectrometer (blue), the soil trapped in pits on the rock surface (red), and the deposit of bright drift on the top of the rock. The area measured by the APXS has the properties expected for nearly unweathered igneous rock, and the soil trapped in the pits is intermediate to the unweathered rock and the highly weathered drift material.

  7. Multispectral processing without spectra

    NASA Astrophysics Data System (ADS)

    Drew, Mark S.; Finlayson, Graham D.

    2003-07-01

    It is often the case that multiplications of whole spectra, component by component, must be carried out, for example when light reflects from or is transmitted through materials. This leads to particularly taxing calculations, especially in spectrally based ray tracing or radiosity in graphics, making a full-spectrum method prohibitively expensive. Nevertheless, using full spectra is attractive because of the many important phenomena that can be modeled only by using all the physics at hand. We apply to the task of spectral multiplication a method previously used in modeling RGB-based light propagation. We show that we can often multiply spectra without carrying out spectral multiplication. In previous work J. Opt. Soc. Am. A 11 , 1553 (1994) we developed a method called spectral sharpening, which took camera RGBs to a special sharp basis that was designed to render illuminant change simple to model. Specifically, in the new basis, one can effectively model illuminant change by using a diagonal matrix rather than the 33 linear transform that results from a three-component finite-dimensional model G. Healey and D. Slater, J. Opt. Soc. Am. A 11 , 3003 (1994). We apply this idea of sharpening to the set of principal components vectors derived from a representative set of spectra that might reasonably be encountered in a given application. With respect to the sharp spectral basis, we show that spectral multiplications can be modeled as the multiplication of the basis coefficients. These new product coefficients applied to the sharp basis serve to accurately reconstruct the spectral product. Although the method is quite general, we show how to use spectral modeling by taking advantage of metameric surfaces, ones that match under one light but not another, for tasks such as volume rendering. The use of metamers allows a user to pick out or merge different volume structures in real time simply by changing the lighting. 2003 Optical Society of America

  8. Multispectral processing without spectra.

    PubMed

    Drew, Mark S; Finlayson, Graham D

    2003-07-01

    It is often the case that multiplications of whole spectra, component by component, must be carried out,for example when light reflects from or is transmitted through materials. This leads to particularly taxing calculations, especially in spectrally based ray tracing or radiosity in graphics, making a full-spectrum method prohibitively expensive. Nevertheless, using full spectra is attractive because of the many important phenomena that can be modeled only by using all the physics at hand. We apply to the task of spectral multiplication a method previously used in modeling RGB-based light propagation. We show that we can often multiply spectra without carrying out spectral multiplication. In previous work [J. Opt. Soc. Am. A 11, 1553 (1994)] we developed a method called spectral sharpening, which took camera RGBs to a special sharp basis that was designed to render illuminant change simple to model. Specifically, in the new basis, one can effectively model illuminant change by using a diagonal matrix rather than the 3 x 3 linear transform that results from a three-component finite-dimensional model [G. Healey and D. Slater, J. Opt. Soc. Am. A 11, 3003 (1994)]. We apply this idea of sharpening to the set of principal components vectors derived from a representative set of spectra that might reasonably be encountered in a given application. With respect to the sharp spectral basis, we show that spectral multiplications can be modeled as the multiplication of the basis coefficients. These new product coefficients applied to the sharp basis serve to accurately reconstruct the spectral product. Although the method is quite general, we show how to use spectral modeling by taking advantage of metameric surfaces, ones that match under one light but not another, for tasks such as volume rendering. The use of metamers allows a user to pick out or merge different volume structures in real time simply by changing the lighting. PMID:12868625

  9. Lick slit spectra of thirty-eight objective prism quasar candidates and low metallicity halo stars

    NASA Technical Reports Server (NTRS)

    Tytler, David; Fan, Xiao-Ming; Junkkarinen, Vesa T.; Cohen, Ross D.

    1993-01-01

    Lick Observatory slit spectra of 38 objects which were claimed to have pronounced UV excess and emission lines are presented. Eleven QSOs, four galaxies at z of about 0.1, 22 stars, and one unidentified object with a low S/N spectrum were found. Of 11 objects which Zhan and Chen (1987, 1989) suggested were QSO with z(prism) not greater than 2.8; eight are QSOs. Six of the QSOs show absorption systems, including Q0000+027A with a relatively strong associated C IV absorption system, and Q0008+008 with a damped Ly-alpha system with an H I column density of 10 exp 21/sq cm. The equivalent widths of the Ca II K line, the G band, and the Balmer lines in 10 stars with the best spectra are measured, and metallicities are derived. Seven of them are in the range -2.5 to -1.7, while the others are less metal-poor.

  10. Einstein spectra of quasars

    NASA Technical Reports Server (NTRS)

    Wilkes, Belinda J.

    1988-01-01

    The results of the initial stage of the CfA survey of quasar energy distributions are reviewed. Einstein imaging proportional counter spectra of 33 quasars have been studied by fitting a single power law slope and absorption by an equivalent column density of neutral hydrogen. Comparison with the higher energy HEAO-A2 data leads to a two-component model for the X-ray spectrum. The X-ray column density is systematically lower than the 21-cm measured Galactic column density along the same line of sight.

  11. 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.

  12. Continuum Fitting HST QSO Spectra

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

  13. AGNs with composite spectra.

    NASA Astrophysics Data System (ADS)

    Veron, P.; Goncalves, A. C.; Veron-Cetty, M.-P.

    1997-03-01

    The use of the Baldwin et al. (1981PASP...93....5B) or Veilleux & Osterbrock (1987ApJS...63..295V) diagnostic diagrams allows the unambiguous classification of the nuclear emission line regions of most galaxies into one of three categories: nuclear HII regions or starbursts, Seyfert 2 galaxies and Liners. However, a small fraction of them have a "transition" spectrum. We present spectral observations of 15 "transition" objects at high-dispersion (66Å/mm) around the Hα, [NII]λλ6548,6584 and/or Hβ, [OIII]λλ4959,5007 emission lines. We show that most of these spectra are composite, due to the simultaneous presence on the slit of a Seyfert nucleus and a HII region. Seyfert 2s and Liners seem to occupy relatively small and distinct volumes in the three-dimensional space λ5007/Hβ, λ6584/Hα, λ6300/Hα.

  14. Interstellar Electron Density Spectra

    NASA Astrophysics Data System (ADS)

    Lambert, Hendrick Clark

    This study concerns the investigation of the form of the wavenumber spectrum of the Galactic electron density fluctuations through an examination of the scattering of the radio pulses emitted by pulsars as they propagate through the diffuse ionized interstellar gas. A widely used model for the electron density spectrum is based on the simple power-law: Pne(q)∝ q-β, where β = 11/3 is usually assumed, corresponding to Kolmogorov's turbulence spectrum. The simple Kolmogorov model provides satisfactory agreement for observations along many lines of sight; however, major inconsistencies remain. The inconsistencies suggest that an increase in the ratio of the power between the high (10-8[ m]-1≤ q<=10-7[ m]-1) and low (10-13[ m]-1≤ q<=10-12[ m]-1) wavenumbers is needed. This enhancement in the ratio can in turn be achieved by either including an inner scale, corresponding to a dissipation scale for the turbulent cascade, in the Kolmogorov spectrum or by considering steeper spectra. Spectra with spectral exponents β > 4 have been in general rejected based on observations of pulsar refractive scintillations. The special case of β = 4 has been given little attention and is analyzed in detail. Physically, this 'β = 4' model corresponds to the random distribution, both in location and orientation, of discrete objects with relatively sharp boundaries across the line of sight. An outer scale is included in the model to account for the average size of such objects. We compare the predictions of the inner-scale and β = 4 models both with published observations and observations we made as part of this investigation. We conclude that the form of the wavenumber spectrum is dependent on the line of sight. We propose a composite spectrum featuring a uniform background turbulence in presence of randomly distributed discrete objects, as modeled by the β = model.

  15. 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 τ = 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

  16. Sequencing BPS spectra

    NASA Astrophysics Data System (ADS)

    Gukov, Sergei; Nawata, Satoshi; Saberi, Ingmar; Stošić, Marko; Sułkowski, Piotr

    2016-03-01

    This paper provides both a detailed study of color-dependence of link homologies, as realized in physics as certain spaces of BPS states, and a broad study of the behavior of BPS states in general. We consider how the spectrum of BPS states varies as continuous parameters of a theory are perturbed. This question can be posed in a wide variety of physical contexts, and we answer it by proposing that the relationship between unperturbed and perturbed BPS spectra is described by a spectral sequence. These general considerations unify previous applications of spectral sequence techniques to physics, and explain from a physical standpoint the appearance of many spectral sequences relating various link homology theories to one another. We also study structural properties of colored HOMFLY homology for links and evaluate Poincaré polynomials in numerous examples. Among these structural properties is a novel "sliding" property, which can be explained by using (refined) modular S-matrix. This leads to the identification of modular transformations in Chern-Simons theory and 3d {N}=2 theory via the 3d/3d correspondence. Lastly, we introduce the notion of associated varieties as classical limits of recursion relations of colored superpolynomials of links, and study their properties.

  17. 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.

  18. The nuclear region of low luminosity flat radio spectrum sources. II. Emission-line spectra

    NASA Astrophysics Data System (ADS)

    Gonçalves, A. C.; Serote Roos, M.

    2004-01-01

    We report on the spectroscopic study of 19 low luminosity Flat Radio Spectrum (LL FRS) sources selected from Marchã's et al. (\\cite{March96}) 200 mJy sample. In the optical, these objects are mainly dominated by the host galaxy starlight. After correcting the data for this effect, we obtain a new set of spectra clearly displaying weak emission lines; such features carry valuable information concerning the excitation mechanisms at work in the nuclear regions of LL FRS sources. We have used a special routine to model the spectra and assess the intensities and velocities of the emission lines; we have analyzed the results in terms of diagnostic diagrams. Our analysis shows that 79% of the studied objects harbour a Low Ionization Nuclear Emission-line Region (or LINER) whose contribution was swamped by the host galaxy starlight. The remaining objects display a higher ionization spectrum, more typical of Seyferts; due to the poor quality of the spectra, it was not possible to identify any possible large Balmer components. The fact that we observe a LINER-type spectrum in LL FRS sources supports the idea that some of these objects could be undergoing an ADAF phase; in addition, such a low ionization emission-line spectrum is in agreement with the black hole mass values and sub-Eddington accretion rates published for some FRS sources. Based on observations collected at the Multiple Mirror Telescope on Mt. Hopkins. Full Fig. 1 is only available in electronic form at http://www.edpsciences.org

  19. Catalogue of representative meteor spectra

    NASA Astrophysics Data System (ADS)

    Vojáček, V.; Borovička, J.; Koten, P.; Spurný, P.; Štork, R.

    2016-01-01

    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 to10 mm. This catalogue is available online at the CDS for those interested in video meteor spectra.

  20. 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)

  1. Reddening and age of six poorly studied star clusters of the Large Magellanic Cloud derived from integrated spectra

    NASA Astrophysics Data System (ADS)

    Minniti, J. H.; Ahumada, A. V.; Clariá, J. J.; Benítez-Llambay, A.

    2014-05-01

    Aims: To increase the number of studied star clusters (SCs) of the Large Magellanic Cloud (LMC), we present flux-calibrated integrated spectra in the optical range (λ = 3700-6800 Å) for six poorly studied LMC SCs of IVA type. This type corresponds to the age range between 200 and 400 Myr. We also aim at creating a new template spectrum representative of this age range at the metallicity level of the LMC. Methods: Foreground reddening E(B - V) values and ages are derived by applying the template matching method that consists of comparing the line strengths and continuum distribution of the cluster spectra with those of template cluster spectra with known properties. The equivalent width (EW) of the Balmer lines and the diagnostic diagrams involving the sum of EWs of selected spectral lines were also employed as age indicators. Results: For the first time, we provide estimates of the clusters' reddenings and ages. As expected, all the clusters appear to be of nearly the same age, their mean value being (400 ± 100) Myr, while the resulting mean E(B - V) values range between 0.00 and 0.10 mag. Conclusions: The present cluster sample complements previous ones in an effort to gather a spectral library with several clusters per age bin. By averaging the reddening-corrected integrated spectra, weighted by their signal-to-noise ratios (S/N), a new high S/N template spectrum of 400 Myr has been created. Integrated spectra for each star cluster 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/565/A49

  2. Measurement and Analysis of Atomic Hydrogen and Diatomic Molecular AlO, C2, CN, and TiO Spectra Following Laser-induced Optical Breakdown

    PubMed Central

    Parigger, Christian G.; Woods, Alexander C.; Witte, Michael J.; Swafford, Lauren D.; Surmick, David M.

    2014-01-01

    In this work, we present time-resolved measurements of atomic and diatomic spectra following laser-induced optical breakdown. A typical LIBS arrangement is used. Here we operate a Nd:YAG laser at a frequency of 10 Hz at the fundamental wavelength of 1,064 nm. The 14 nsec pulses with anenergy of 190 mJ/pulse are focused to a 50 µm spot size to generate a plasma from optical breakdown or laser ablation in air. The microplasma is imaged onto the entrance slit of a 0.6 m spectrometer, and spectra are recorded using an 1,800 grooves/mm grating an intensified linear diode array and optical multichannel analyzer (OMA) or an ICCD. Of interest are Stark-broadened atomic lines of the hydrogen Balmer series to infer electron density. We also elaborate on temperature measurements from diatomic emission spectra of aluminum monoxide (AlO), carbon (C2), cyanogen (CN), and titanium monoxide (TiO). The experimental procedures include wavelength and sensitivity calibrations. Analysis of the recorded molecular spectra is accomplished by the fitting of data with tabulated line strengths. Furthermore, Monte-Carlo type simulations are performed to estimate the error margins. Time-resolved measurements are essential for the transient plasma commonly encountered in LIBS. PMID:24561875

  3. Spectra ID of recent SN

    NASA Astrophysics Data System (ADS)

    Challis, Peter

    2013-12-01

    P. Challis, Harvard-Smithsonian Center for Astrophysics (CfA), on behalf of the CfA Supernova Group, report spectra (range 320-860 nm) of various SN obtained during Dec. 24-27 UT by P. Challis, S. Gottilla (MMTO.org), and E. Marin (MMTO.org) with the MMT 6.5-m telescope (+ Blue Channel). Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J.

  4. Estimators of bottom reflectance spectra

    NASA Technical Reports Server (NTRS)

    Estep, L.; Holloway, J.

    1992-01-01

    Estimators of in situ bottom spectral reflectance are calculated from multi-station optical field data gathered with standard instrumentation from different sites. These spectra are then compared to reflectance spectra measured in the laboratory of the bottom sediments collected in the field for the stations at these different sites. The relative fit of the estimated spectral curves to those measured in the laboratory was measured. The most accurate absolute estimation was provided by the single scattering irradiance model.

  5. The composite load spectra project

    NASA Technical Reports Server (NTRS)

    Newell, J. F.; Ho, H.; Kurth, R. E.

    1990-01-01

    Probabilistic methods and generic load models capable of simulating the load spectra that are induced in space propulsion system components are being developed. Four engine component types (the transfer ducts, the turbine blades, the liquid oxygen posts and the turbopump oxidizer discharge duct) were selected as representative hardware examples. The composite load spectra that simulate the probabilistic loads for these components are typically used as the input loads for a probabilistic structural analysis. The knowledge-based system approach used for the composite load spectra project provides an ideal environment for incremental development. The intelligent database paradigm employed in developing the expert system provides a smooth coupling between the numerical processing and the symbolic (information) processing. Large volumes of engine load information and engineering data are stored in database format and managed by a database management system. Numerical procedures for probabilistic load simulation and database management functions are controlled by rule modules. Rules were hard-wired as decision trees into rule modules to perform process control tasks. There are modules to retrieve load information and models. There are modules to select loads and models to carry out quick load calculations or make an input file for full duty-cycle time dependent load simulation. The composite load spectra load expert system implemented today is capable of performing intelligent rocket engine load spectra simulation. Further development of the expert system will provide tutorial capability for users to learn from it.

  6. 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.

  7. 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.

  8. 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.

  9. AVIRIS spectra of California wetlands

    NASA Technical Reports Server (NTRS)

    Gross, Michael F.; Ustin, Susan L.; Klemas, Vytautas

    1988-01-01

    Spectral data gathered by the AVIRIS from wetlands in the Suisun Bay area of California on 13 October 1987 were analyzed. Spectra representing stands of numerous vegetation types (including Sesuvium verrucosum, Scirpus acutus and Scirpus californicus, Xanthium strumarium, Cynadon dactylon, and Distichlis spicata) and soil were isolated. Despite some defects in the data, it was possible to detect vegetation features such as differences in the location of the chlorophyll red absorption maximum. Also, differences in cover type spectra were evident in other spectral regions. It was not possible to determine if the observed features represent noise, variability in canopy architecture, or chemical constituents of leaves.

  10. 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.

  11. 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 (κ) 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 κ. However in 2 projects, MASE and ICE-T, simultaneous DMA measurements also provided κ by transposing DMA sizes to Sc; the κ 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 κ of the processed modes was greater than mean κ of the unprocessed modes, chemical processing was indicated; since most κ were lower than ammonium sulfate κ (0.61) chemical processing should move processed κ 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 κ and less bimodality than below cloud measurements, this is consistent with the higher above cloud NCCN, that κ 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

  12. NIST Databases on Atomic Spectra

    NASA Astrophysics Data System (ADS)

    Reader, J.; Wiese, W. L.; Martin, W. C.; Musgrove, A.; Fuhr, J. R.

    2002-11-01

    The NIST atomic and molecular spectroscopic databases now available on the World Wide Web through the NIST Physics Laboratory homepage include Atomic Spectra Database, Ground Levels and Ionization Energies for the Neutral Atoms, Spectrum of Platinum Lamp for Ultraviolet Spectrograph Calibration, Bibliographic Database on Atomic Transition Probabilities, Bibliographic Database on Atomic Spectral Line Broadening, and Electron-Impact Ionization Cross Section Database. The Atomic Spectra Database (ASD) [1] offers evaluated data on energy levels, wavelengths, and transition probabilities for atoms and atomic ions. Data are given for some 950 spectra and 70,000 energy levels. About 91,000 spectral lines are included, with transition probabilities for about half of these. Additional data resulting from our ongoing critical compilations will be included in successive new versions of ASD. We plan to include, for example, our recently published data for some 16,000 transitions covering most ions of the iron-group elements, as well as Cu, Kr, and Mo [2]. Our compilations benefit greatly from experimental and theoretical atomic-data research being carried out in the NIST Atomic Physics Division. A new compilation covering spectra of the rare gases in all stages of ionization, for example, revealed a need for improved data in the infrared. We have thus measured these needed data with our high-resolution Fourier transform spectrometer [3]. An upcoming new database will give wavelengths and intensities for the stronger lines of all neutral and singly-ionized atoms, along with energy levels and transition probabilities for the persistent lines [4]. A critical compilation of the transition probabilities of Ba I and Ba II [5] has been completed and several other compilations of atomic transition probabilities are nearing completion. These include data for all spectra of Na, Mg, Al, and Si [6]. Newly compiled data for selected ions of Ne, Mg, Si and S, will form the basis for a new

  13. 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``).

  14. Catalogue of representative meteor spectra

    NASA Astrophysics Data System (ADS)

    Vojáček, V.; Borovička, 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 δ 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

  15. Accelerated Fitting of Stellar Spectra

    NASA Astrophysics Data System (ADS)

    Ting, Yuan-Sen; Conroy, Charlie; Rix, Hans-Walter

    2016-07-01

    Stellar spectra are often modeled and fitted by interpolating within a rectilinear grid of synthetic spectra to derive the stars’ labels: stellar parameters and elemental abundances. However, the number of synthetic spectra needed for a rectilinear grid grows exponentially with the label space dimensions, precluding the simultaneous and self-consistent fitting of more than a few elemental abundances. Shortcuts such as fitting subsets of labels separately can introduce unknown systematics and do not produce correct error covariances in the derived labels. In this paper we present a new approach—Convex Hull Adaptive Tessellation (chat)—which includes several new ideas for inexpensively generating a sufficient stellar synthetic library, using linear algebra and the concept of an adaptive, data-driven grid. A convex hull approximates the region where the data lie in the label space. A variety of tests with mock data sets demonstrate that chat can reduce the number of required synthetic model calculations by three orders of magnitude in an eight-dimensional label space. The reduction will be even larger for higher dimensional label spaces. In chat the computational effort increases only linearly with the number of labels that are fit simultaneously. Around each of these grid points in the label space an approximate synthetic spectrum can be generated through linear expansion using a set of “gradient spectra” that represent flux derivatives at every wavelength point with respect to all labels. These techniques provide new opportunities to fit the full stellar spectra from large surveys with 15–30 labels simultaneously.

  16. Vibrational spectra of fluorohafnate glass

    NASA Astrophysics Data System (ADS)

    Bendow, Bernard; Drexhage, Martin G.; Banerjee, Pranab K.; Goltman, John; Mitra, Shashanka S.; Moynihan, Cornelius T.

    1981-02-01

    We report the first detailed measurements of fundamental vibrational spectra in fluorohafnate glass. The Raman spectrum is dominated by a single relatively broad peak in the vicinity of 570-590 cm -1 attributed to Hf-F stretching modes, while the infrared spectrum displays two prominent broad peaks. The location of the high frequency peaks is shown to be consistent with the observed position of the infrared absorption edge.

  17. Near-infrared spectra and intrinsic luminosities of candidate type II quasars at 2 < z < 3.4

    SciTech Connect

    Greene, Jenny E.; Strauss, Michael A.; Pattarakijwanich, Petchara; Alexandroff, Rachael; Zakamska, Nadia L.; Liu, Guilin; Lang, Dustin; Hamann, Frederick; Ross, Nicholas P.; Myers, Adam D.; Brandt, W. Niel; Schneider, Donald P.; York, Donald

    2014-06-10

    We present JHK near-infrared (NIR) spectroscopy of 25 candidate Type II quasars selected from the Sloan Digital Sky Survey (SDSS), using Triplespec on the Apache Point Observatory 3.5 m telescope, the Folded-port InfraRed Echellette at the Magellan/Baade 6.5 m telescope, and the Gemini Near-Infrared Spectrograph on Gemini. At redshifts of 2 < z < 3.4, our NIR spectra probe the rest-frame optical region of these targets, which were initially selected to have strong lines of C IV and Ly α, with FWHM < 2000 km s{sup –1} from the SDSS pipeline. We use the [O III] λ5007 line shape as a model for the narrow-line region emission and find that Hα consistently requires a broad component with FWHMs ranging from 1000 to 7500 km s{sup –1}. Interestingly, the C IV lines also require broad bases, but with considerably narrower widths of 1000-4500 km s{sup –1}. Estimating the extinction using the Balmer decrement and also the relationship in lower-z quasars between rest equivalent width and luminosity in the [O III] line, we find typical A{sub V} values of 0-2 mag, which naturally explains the attenuated C IV lines relative to Hα. We propose that our targets are moderately obscured quasars. We also describe one unusual object with three distinct velocity peaks in its [O III] spectrum.

  18. Optical Spectra of Triggered Lightning

    NASA Astrophysics Data System (ADS)

    Walker, T. D.; Biagi, C. J.; Hill, J. D.; Jordan, D. M.; Uman, M. A.; Christian, H. J., Jr.

    2009-12-01

    In August 2009, the first optical spectra of triggered lightning flashes were acquired. Data from two triggered lightning flashes were obtained at the International Center for Lightning Research and Testing in north-central Florida. The spectrometer that was used has an average dispersion of 260 Å/mm resulting in an average resolution of 5 Å when mated to a Photron (SA1.1) high-speed camera. The spectra captured with this system had a free spectral range of 3800-8000 Å. The spectra were captured at 300,000 frames per second. The spectrometer's vertical field of view was 3 m at an altitude 50 m above the launch tower, intended to view the middle of the triggering wire. Preliminary results show that the copper spectrum dominated the earliest part of the flash and copper lines persisted during the total lifetime of the detectable spectrum. Animations over the lifetime of the stroke from the initial wire illumination to multiple return strokes show the evolution of the spectrum. In addition, coordinated high speed channel base current, electric field and imagery measurements of the exploding wire, downward leaders, and return strokes were recorded. Quantitative analysis of the spectral evolution will be discussed in the context of the overall flash development.

  19. Prediction of earthquake response spectra

    USGS Publications Warehouse

    Joyner, W.B.; Boore, David M.

    1982-01-01

    We have developed empirical equations for predicting earthquake response spectra in terms of magnitude, distance, and site conditions, using a two-stage regression method similar to the one we used previously for peak horizontal acceleration and velocity. We analyzed horizontal pseudo-velocity response at 5 percent damping for 64 records of 12 shallow earthquakes in Western North America, including the recent Coyote Lake and Imperial Valley, California, earthquakes. We developed predictive equations for 12 different periods between 0.1 and 4.0 s, both for the larger of two horizontal components and for the random horizontal component. The resulting spectra show amplification at soil sites compared to rock sites for periods greater than or equal to 0.3 s, with maximum amplification exceeding a factor of 2 at 2.0 s. For periods less than 0.3 s there is slight deamplification at the soil sites. These results are generally consistent with those of several earlier studies. A particularly significant aspect of the predicted spectra is the change of shape with magnitude (confirming earlier results by McGuire and by Irifunac and Anderson). This result indicates that the conventional practice of scaling a constant spectral shape by peak acceleration will not give accurate answers. The Newmark and Hall method of spectral scaling, using both peak acceleration and peak velocity, largely avoids this error. Comparison of our spectra with the Nuclear Regulatory Commission's Regulatory Guide 1.60 spectrum anchored at the same value at 0.1 s shows that the Regulatory Guide 1.60 spectrum is exceeded at soil sites for a magnitude of 7.5 at all distances for periods greater than about 0.5 s. Comparison of our spectra for soil sites with the corresponding ATC-3 curve of lateral design force coefficient for the highest seismic zone indicates that the ATC-3 curve is exceeded within about 7 km of a magnitude 6.5 earthquake and within about 15 km of a magnitude 7.5 event. The amount by

  20. Detection of Broad Hα 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.; Woźniak, 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 Hα 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 Hα 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.

  1. EXTINCTION IN STAR-FORMING DISK GALAXIES FROM INCLINATION-DEPENDENT COMPOSITE SPECTRA

    SciTech Connect

    Yip, Ching-Wa; Szalay, Alex S.; Wyse, Rosemary F. G.; Budavari, Tamas; Dobos, Laszlo; Csabai, Istvan E-mail: szalay@pha.jhu.ed

    2010-02-01

    Extinction in galaxies affects their observed properties. In scenarios describing the distribution of dust and stars in individual disk galaxies, the amplitude of the extinction can be modulated by the inclination of the galaxies. In this work, we investigate the inclination dependency in composite spectra of star-forming disk galaxies from the Sloan Digital Sky Survey Data Release 5. In a volume-limited sample within a redshift range 0.065-0.075 and a r-band Petrosian absolute magnitude range -19.5 to -22 mag which exhibits a flat distribution of inclination, the inclined relative to face-on extinction in the stellar continuum is found empirically to increase with inclination in the g, r, and i bands. Within the central 0.5 intrinsic half-light radius of the galaxies, the g-band relative extinction in the stellar continuum for the highly inclined objects (axis ratio b/a = 0.1) is 1.2 mag, agreeing with previous studies. The extinction curve of the disk galaxies is given in the rest-frame wavelengths 3700-8000 A, identified with major optical emission and absorption lines in diagnostics. The Balmer decrement, Halpha/Hbeta, remains constant with inclination, suggesting a different kind of dust configuration and/or reddening mechanism in the H II region from that in the stellar continuum. One factor is shown to be the presence of spatially non-uniform interstellar extinction, presumably caused by clumped dust in the vicinity of the H II region.

  2. DUO: Spectra of diatomic molecules

    NASA Astrophysics Data System (ADS)

    Yurchenko, Sergei N.; Lodi, Lorenzo; Tennyson, Jonathan; Stolyarov, Andrey V.

    2016-05-01

    Duo computes rotational, rovibrational and rovibronic spectra of diatomic molecules. The software, written in Fortran 2003, solves the Schrödinger equation for the motion of the nuclei for the simple case of uncoupled, isolated electronic states and also for the general case of an arbitrary number and type of couplings between electronic states. Possible couplings include spin–orbit, angular momenta, spin-rotational and spin–spin. Introducing the relevant couplings using so-called Born–Oppenheimer breakdown curves can correct non-adiabatic effects.

  3. Satellite spectra of heliumlike nickel

    SciTech Connect

    Hsuan, H.; Bitter, M.; Hill, K.W.; von Goeler, S. Grek, B.; Johnson, D.; Johnson, L.C.; Sesnic, S.; Bhalla, C.P.; Karim, K.R.

    1987-02-01

    Spectra of heliumlike nickel, NiXXVII, have been observed from Tokamak Fusion Test Reactor (TFTR) plasmas with a high resolution crystal spectrometer. The experimental arrangement permits simultaneous observation of the heliumlike resonance line, the intercombination and forbidden lines, and all the associated satellites due to transitions 1s/sup 2/nl - 1s2l'nl'' with N greater than or equal to 2. Relative wavelengths and line intensities can thus be determined very accurately. The observed spectral data are in good agreement with results from the present Hartree-Fock-Slater atomic model calculations and predictions from the Z-expansion method.

  4. Identified hadron spectra from PHOBOS

    NASA Astrophysics Data System (ADS)

    Veres, Gábor I.; PHOBOS Collaboration; Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Becker, B.; Betts, R. R.; Bickley, A. A.; Bindel, R.; Busza, W.; Carroll, A.; Decowski, M. P.; García, E.; Gburek, T.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Harrington, A. S.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Holynski, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Khan, N.; Kulinich, P.; Kuo, C. M.; Lee, J. W.; Lin, W. T.; Manly, S.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Roland, C.; Roland, G.; Sagerer, J.; Sarin, P.; Sedykh, I.; Skulski, W.; Smith, C. E.; Steinberg, P.; Stephans, G. S. F.; Sukhanov, A.; Tonjes, M. B.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Wolfs, F. L. H.; Wosiek, B.; Wozniak, K.; Wyslouch, B.; Zhang, J.

    2004-08-01

    Transverse momentum spectra of pions, kaons and protons, as well as antiparticle to particle ratios near mid-rapidity from d+Au collisions at \\sqrt{s_{{\\rm NN}}} = 200\\,{\\rm GeV} have been measured by the PHOBOS experiment at RHIC. The transverse momentum range of particle identification was extended to beyond 3 GeV/c using the TOF detector and a new trigger system. The pseudorapidity dependence of the nuclear modification factor for charged hadrons in d+Au collisions is presented.

  5. 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.

  6. Planetary spectra for anisotropic scattering

    NASA Technical Reports Server (NTRS)

    Chamberlain, J. W.

    1975-01-01

    Some of the effects on planetary spectra that would be produced by departures from isotropic scattering are examined. The phase function is the simplest departure to handle analytically and the only phase function, other than the isotropic one, that can be incorporated into a Chandrasekhar first approximation. This approach has the advantage of illustrating trends resulting from anisotropies while retaining the simplicity that yields physical insight. An algebraic solution to the two sets of anisotropic H functions is developed in the appendix. It is readily adaptable to progammable desk calculators and gives emergent intensities accurate to 0.3 percent, which is sufficient even for spectroscopic analysis.

  7. Energy spectra and LET spectra of protons behind shielding

    NASA Astrophysics Data System (ADS)

    Katz, Sari; Barak, Joseph

    2014-08-01

    With the advent of devices sensitive to SEU due to direct ionization by protons, it became important to know the flux and energies of protons behind aluminum shielding or within satellites. We present new analytically derived expressions for the energy distribution of incident protons, after passing the shielding, and of secondary protons emitted within the shielding. The results are compared with those of the MULASSIS code. In some cases, like a satellite in a GCR orbit, the contribution of the secondary protons to SEU might be the dominant one. Proton energy-distributions behind shielding are proportional, at low energy values, to inverse proton-LET in aluminum. Their calculated LET-spectra in silicon can be used for evaluating SEU-rate in space. The analytic expressions presented here can be useful in calculating the influence of shielding on other incident ions and secondary ions.

  8. Spectra from pair-equilibrium plasmas

    NASA Technical Reports Server (NTRS)

    Zdziarski, A. A.

    1984-01-01

    A numerical model of relativistic nonmagnetized plasma with uniform temperature and electron density distributions is considered, and spectra from plasma in pair equilibrium are studied. A range of dimensionless temperature (T) greater than about 0.2 is considered. The spectra from low pair density plasmas in pair equilibrium vary from un-Comptonized bremsstrahlung spectra at Thomson cross section tau(N) much less than one to Comptonized bremsstrahlung spectra with tau(N) over one. For high pair density plasmas the spectra are flat for T greater than about one, and have broad intensity peaks at energy roughly equal to 3T for T less than one. In the latter region the total luminosity is approximately twice the annihilation luminosity. All spectra are flat in the X-ray region, in contradiction to observed AGN spectra. For dimensionless luminosity greater than about 100, the cooling time becomes shorter than the Thomson time.

  9. Energy spectra in bubbly turbulence

    NASA Astrophysics Data System (ADS)

    Luther, Stefan; van den Berg, Thomas H.; Rensen, Judith; Lohse, Detlef

    2004-11-01

    The energy spectrum of single phase turbulent flow - apart from intermittency corrections - has been known since Kolomogorov 1941, E(k) ∝ k-5/3. How do bubbles modify this spectrum? To answer this question, we inject micro bubbles (radius 100 μm) in fully turbulent flow (Re_λ=200) up to volume concentrations of 0.3 %. Energy spectra and velocity structure functions are measured with hot-film anemometry. Under our experimental conditions, we find an enhancement of energy on small scales confirming numerical predictions by Mazzitelli, Lohse, and Toschi [Phys. Fluids 15, L5 (2003)]. They propose a mechanism in which bubbles are clustering most likely in downflow regions. This clustering is a lift force effect suppressing large vortical structures, while enhancing energy input on small scales.

  10. 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 μm 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.

  11. Optimal Extraction of Echelle Spectra

    NASA Astrophysics Data System (ADS)

    Piskunov, Nikolai

    The extraction of the echelle spectra registered with a CCD detector represents a big challenge because of three reasons: (1) the pixel sampling is often close or worse then optimal, (2) spectral orders are curved and tilted with respect to the CCD rows (or columns) and (3) every pixel contains additional noise coming from various sources as illustrated in Figure 1. The main goal of an optimal extraction is to recover as much of the science signal while minimizing the contribution of the noise. Here we present the Slit Function Decomposition algorithm which replaces the summation in a sliding window with a reconstruction of the slit illumination profile. The reconstruction is formulated as an inverse problem solved by iterations and it is robust against most of the systematic problems including cosmic rays and cosmetic defects.

  12. 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}

  13. 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 ω³ increase and initiates an ω⁻⁷ 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.

  14. Line Coupling in Atmospheric Spectra

    NASA Technical Reports Server (NTRS)

    Tipping, R. H.

    1996-01-01

    The theoretical modeling of atmospheric spectra is important for a number of different applications: for instance, in the determination of minor atmospheric constituents such as ozone, carbon dioxide, CFC's etc.; in monitoring the temperature profile for climate studies; and in measuring the incoming and outgoing radiation to input into global climate models. In order to accomplish the above mentioned goal, one needs to know the spectral parameters characterizing the individual spectral lines (frequency, width, strength, and shape) as well as the physical parameters of the atmosphere (temperature, abundances, and pressure). When all these parameters are known, it is usually assumed that the resultant spectra and concomitant absorption coefficient can then be calculated by a superposition of individual profiles of appropriate frequency, strength and shape. However, this is not true if the lines are 'coupled'. Line coupling is a subtle effect that takes place when lines of a particular molecule overlap in frequency. In this case when the initial states and the final states of two transitions are connected by collisions, there is a quantum interference resulting in perturbed shapes. In general, this results in the narrowing of Q-branches (those in which the rotational quantum number does not change), and vibration-rotational R- and P branches (those in which the rotational quantum number changes by +/- 1), and in the spectral region beyond band heads (regions where the spectral lines pile up due to centrifugal distortion). Because these features and spectral regions are often those of interest in the determination of the abundances and pressure-temperature profiles, one must take this effect into account in atmospheric models.

  15. Rest-Frame Optical Spectra of Three Strongly Lensed Galaxies at z~2

    SciTech Connect

    Hainline, Kevin N.; Shapley, Alice E.; Kornei, Katherine A.; Pettini, Max; Buckley-Geer, Elizabeth; Allam, Sahar S.; Tucker, Douglas L.; /Fermilab

    2009-06-01

    We present Keck II NIRSPEC rest-frame optical spectra for three recently discovered lensed galaxies: the Cosmic Horseshoe (z = 2.38), the Clone (z = 2.00), and SDSS J090122.37+181432.3 (z = 2.26). The boost in signal-to-noise ratio (S/N) from gravitational lensing provides an unusually detailed view of the physical conditions in these objects. A full complement of high S/N rest-frame optical emission lines is measured, spanning from rest frame 3600 to 6800 {angstrom}, including robust detections of fainter lines such as H{gamma}, [S II]{lambda}6717,6732, and in one instance [Ne III]{lambda}3869. SDSS J090122.37+181432.3 shows evidence for active galactic nucleus activity, and therefore we focus our analysis on star-forming regions in the Cosmic Horseshoe and the Clone. For these two objects, we estimate a wide range of physical properties. Current lensing models for the Cosmic Horseshoe and the Clone allow us to correct the measured H{alpha} luminosity and calculated star formation rate. Metallicities have been estimated with a variety of indicators, which span a range of values of 12+ log(O/H) = 8.3-8.8, between {approx}0.4 and {approx}1.5 of the solar oxygen abundance. Dynamical masses were computed from the H{alpha} velocity dispersions and measured half-light radii of the reconstructed sources. A comparison of the Balmer lines enabled measurement of dust reddening coefficients. Variations in the line ratios between the different lensed images are also observed, indicating that the spectra are probing different regions of the lensed galaxies. In all respects, the lensed objects appear fairly typical of ultraviolet-selected star-forming galaxies at z {approx} 2. The Clone occupies a position on the emission-line diagnostic diagram of [O III]/H{beta} versus [N II]/H{alpha} that is offset from the locations of z {approx} 0 galaxies. Our new NIRSPEC measurements may provide quantitative insights into why high-redshift objects display such properties. From the [S II

  16. Energy Distributions and spectra of Orion B stars

    NASA Technical Reports Server (NTRS)

    Schild, R. E.; Chaffee, F.

    1972-01-01

    New MK spectral types and energy distributions are presented for B stars in Orion for which far ultraviolet flux excesses have recently been discovered. Significant differences between HD spectral energy distributions show the Orion late B stars to have smaller Balmer discontinuities than do field stars of the same spectral types. For the late B stars, these effects cause the 1500 A fluxes to be under-estimated by approximately 0.5 mag. No comparable systematic effects were found for the early B stars.

  17. Blind extraction of exoplanetary spectra

    NASA Astrophysics Data System (ADS)

    Morello, Giuseppe; Waldmann, Ingo P.; Tinetti, Giovanna

    2016-06-01

    In the last decade, remote sensing spectroscopy enabled characterization of the atmospheres of extrasolar planets. Transmission and emission spectra of tens of transiting exoplanets have been measured with multiple instruments aboard Spitzer and Hubble Space Telescopes as well as ground-based facilities, revealing the presence of atomic, ionic and molecular species in their atmospheres, and constraining their temperature and pressure profiles.Early analyses were somehow heuristic both in measuring the spectra and in their interpretation, leading to some controversies in the literature.A photometric precision of 0.01% is necessary to detect the atmospheric spectral modulations. Current observatories, except Kepler, were not designed to achieve this precision. Data reduction is necessary to minimize the effect of instrument systematics in order to achieve the target precision. In the past, parametric models have extensively been used by most teams to remove correlated noise with the aid of auxiliary information of the instrument, the so-called optical state vectors (OSVs). Such OSVs can include inter- and intra-pixel position of the star or its spectrum, instrument temperatures and inclinations, and/or other parameters. In some cases, different parameterizations led to discrepant results.We recommend the use of blind non-parametric data detrending techniques to overcome those issues. In particular, we adopt Independent Component Analysis (ICA), i.e. a blind source separation (BSS) technique to disentangle the multiple instrument systematics and astrophysical signals in transit/eclipse light curves. ICA does not require a model for the systematics, and for this reason, it can be applied to any instrument with little changes, if any. ICA-based algorithms have been applied to Spitzer/IRAC and synthetic observations in photometry (Morello et al. 2014, 2015, 2016; Morello 2015) and to Hubble/NICMOS and Spitzer/IRS in spectroscopy (Waldmann 2012, 2014, Waldmann et al. 2013

  18. Dual spectra well logging system

    SciTech Connect

    Nussbaum, T.W.

    1982-09-07

    A dual spectra well logging system includes a well logging tool which is adapted to pass through a bore hole in an earth formation. The well logging tool includes at least two sensors which sense at least one condition of the earth formation and provides corresponding pulse signals. A circuit connected to the sensors provides a combined pulse signal wherein the pulses of the pulse signal from one sensor has one polarity and the pulses of the pulse signal from the other sensor has pulses of an opposite polarity. A circuit applies the combined pulse signal to a well logging cable which conducts the combined pulse signal to the surface of the earth formation. Surface apparatus includes a network connected to the cable which provides control signals in accordance with the polarity of the pulses in the combined pulse signal. A network connected to the cable inverts the combined pulse signal and provides a combined pulse signal and an inverted combined pulse signal. A first switching network receiving the combined pulse signal passes the pulses derived from the pulses of the one polarity in acccordance with the control signals to provide a first pulse signal while a second switching network receiving the inverted combined pulse signal passes the pulses derived from the pulses of the opposite polarity in accordance with the control signals to provide a second pulse signal. An output network processes the two pulse signals to provide an indication of the earth's condition in accordance with the processed pulse signals.

  19. Infrared spectra of protostellar collapse

    NASA Technical Reports Server (NTRS)

    Hollenbach, David J.; Ceccarelli, Cecilia; Neufeld, David A.; Tielens, Alexander G. G. M.

    1995-01-01

    Theoretical models of the formation of low mass stars by cloud collapse predict that OI(63 micrometers) and IR rotational lines of CO and H2O dominate the cooling in the freefalling region 10-1000 AU from the protostar. The freefalling gas supersonically hits the protoplanetary disk orbiting the protostar, forming an accretion shock with strong IR emission in rotational lines of H2O and OH, and OI(63 microns). The accretion shock spectra and line profiles depend on the mass flux through the shock and the typical distance r-bar at which the freefalling gas strikes the disk. The line widths are of order the Keplerian speed, or approx. 10(r-bar/10AU)(exp -0.5) km/s, for the accretion shock lines, and less for the lines from the infalling gas. Measurements of the IR line fluxes and profiles from the freefalling gas and the accretion shock diagnoses how a protostar and disk are formed and requires high sensitivity and high spectral and spatial resolving power. SOFIA will be the optimum observatory for many of these lines, although ISO will contribute and the KAO may make a few pioneering detections.

  20. Interpretation of Nitroindolinospirobenzothiopyran Vibrational Spectra

    NASA Astrophysics Data System (ADS)

    Gladkov, L. L.; Khamchukov, Yu. D.; Lyubimov, A. V.

    2016-05-01

    The structures of four possible stereoisomers of the closed form of photochromic nitroindolinospirobenzothiopyran (NISTP) {1',3'-dihydro-1',3',3'-trimethyl-6-nitrospiro[2H-1-benzothiopyran-2,2'-(2H)-indoline]} were determined by the DFT method. The geometry of the most stable isomer was defined. Nitro-substitution changes mainly the lengths of bonds formed by S and N with spiro-atom Cs. According to the calculations, the CsS bond changes most and lengthens by 0.019 Å. It is shown that the S atom has large displacement amplitudes in normal modes assigned to Raman lines at 230, 285, 360, and 575 cm-1 and weak IR bands at 467 and 577 cm-1. Oscillations involving the nitro group are very active in Raman and IR spectra. Their frequencies are slightly lower than similar frequencies of nitrobenzene and nitroindolinospirobenzopyran, indicating a higher degree of vibrational coupling of the NO2 group with the NISTP molecular skeleton.

  1. Reflectance spectra of subarctic lichens

    NASA Technical Reports Server (NTRS)

    Petzold, Donald E.; Goward, Samuel N.

    1988-01-01

    Lichens constitute a major portion of the ground cover of high latitude environments, but little has been reported concerning their in situ solar spectral reflectance properties. Knowledge of these properties is important for the interpretation of remotely sensed observations from high latitude regions, as well as in studies of high latitude ecology and energy balance climatology. The spectral reflectance of common boreal vascular plants is similar to that of vascular plants of the midlatitudes. The dominant lichens, in contrast, display variable reflectance patterns in visible wavelengths. The relative reflectance peak at 0.55 microns, common to green vegetation, is absent or indistinct in spectra of pervasive boreal forest and tundra lichens, despite the presence of chlorophyll in the inner algal cells. Lichens of the dominant genus, Cladina, display strong absorption of ultraviolet energy and short-wavelength blue light relative to their absorption in other visible wavelengths. Since the Cladinae dominate both the surface vegetation in open woodlands of the boreal forest and the low arctic tundra, their unusual spectral reflectance patterns will enable accurate monitoring of the boreal forest-tundra ecotone and detection of its vigor and movement in the future.

  2. Overcoming Degeneracies in Exoplanet Spectra

    NASA Astrophysics Data System (ADS)

    Benneke, Björn

    2015-08-01

    Spectroscopic observations of exoplanets can provide invaluable insights into the planets’ compositions, their formation and evolution histories, and even their habitability. Obtaining exoplanet spectra is observationally challenging; however, and we are generally limited to relatively low signal-to-noise, low spectral resolution, disk-integrated observations , often with relatively narrow wavelength coverage. This low data situation results in strong correlations and degeneracies between the different planet and atmospheric parameters of interest. In this talk, I will present a conceptual picture of how vital information about the planet is encoded in its observable spectrum. I will then give an overview about the wide range of correlations and degeneracies relevant to today’s exoplanet observations. Finally, I will demonstrate how some degeneracies can be overcome and improved constraints can be obtained by including prior knowledge of atmospheric chemistry and physics in the retrieval. I present a new atmospheric retrieval framework, SCARLET, that combines observational data and our prior (limited) knowledge of atmospheric processes in a statistical robust Bayesian framework. New results for hot Jupiters will be presented.

  3. X-ray spectra of supernova remnants

    NASA Technical Reports Server (NTRS)

    Szymkowiak, A. E.

    1985-01-01

    X-ray spectra were obtained from fields in three supernova remnants with the solid state spectrometer of the HEAO 2 satellite. These spectra, which contain lines from K-shell transitions of several abundant elements with atomic numbers between 10 and 22, were compared with various models, including some of spectra that would be produced by adiabatic phase remnants when the time-dependence of the ionization is considered.

  4. 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.

  5. Infrared spectra of thyroid tumor tissues

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

    We used infrared spectroscopy methods to study thyroid tumor tissues removed during surgery. The IR spectra of the surgical material are compared with data from histological examination. We show that in malignant neoplasms, the spectra of proteins in the region of C=O vibrations are different from the spectra of these substances in benign tumors and in tissues outside the pathological focus at a distance >1 cm from the margin of the tumor. The differences in the spectra are due to changes in the supermolecular structure of the proteins, resulting from rearrangement of the system of hydrogen bonds. We identify the spectral signs of malignant pathologies.

  6. Incorporating Spectra Into Periodic Timing

    NASA Astrophysics Data System (ADS)

    Connors, Alanna; Hong, J.; Protopapas, P.; Kashyap, V.

    2011-09-01

    The Chandra surveys have resulted in a wealth of data on low-luminosity X-ray sources (Lx 1030-34 erg/s) of Galactic scales beyond the local solar neighborhood. Many of these are compact binaries, in particular, cataclysmic variables, often identified by their periodic X-ray variability and spectra. Hong et al. (2009, 2011) have used energy quantiles (Hong, Schlegel & Grindlay, 2004) as a fast, robust indicator of spectral hardness and absorption of the X-ray sources. Energy quantiles also enable a simple but effective illustration of spectral changes with phase in these periodic systems: e.g. absorption by the accreting material is understood to drive the periodic light-curves. An interesting question is how to best make use of the information encapsulated in the periodic change in energy spectrum, along with the periodic change in intensity, especially for cases of ambiguous period determination? And, how to do it computationally efficiently? A first approach is to do the period search in intensity, as is standard; and then use a criterion of spectral variation to verify possible periods. Huijse, Zegers & Protopapas (2011) recently demonstrated a powerful period estimation technique using information potential and correntropy embedded in the light curve. Similar quantities based on energies (or energy quantiles) of X-ray photons can serve as criteria of spectral variation. A different approach treats the spectrum variations and intensity variations completely independently, searching through period-space in each, and then combining the results. A more general method would include both at the same time, looking for statistically significant variations above what is expected for a constant (in intensity and spectrum).

  7. Spectra of the Jovian ring and Amalthea

    NASA Technical Reports Server (NTRS)

    Neugebauer, G.; Becklin, E. E.; Jewitt, D. C.; Danielson, G. E.; Terrile, R. J.

    1981-01-01

    Measurements made between 0.887 and 2.4 microns demonstrate that the Jovian ring and Amalthea have similar reflection spectra. The spectra, in particular the ratio of the 0.9- to 2.2-micron reflectivities, are inconsistent with those expected from water, ammonia, or methane frosts, but are consistent with reflection from large rock bodies.

  8. Heavy primary spectra observed by RUNJOB

    NASA Astrophysics Data System (ADS)

    Apanasenko, A. V.; Beresovskaya, V. A.; Fujii, M.; Galkin, V. I.; Hareyama, M.; Ichimura, M.; Ito, S.; Kamioka, E.; Kitami, T.; Kobayashi, T.; Kopenkin, V. V.; Kuramata, S.; Kuriyama, T.; Lapshin, V. I.; Managadze, A. K.; Matsutani, H.; Mikami, H.; Misnikova, N. P.; Mukhamedshin, R. A.; Namiki, M.; Nanjo, H.; Nazarov, S. N.; Nikolsky, S. I.; Oe, T.; Ohta, S.; Osedlo, V. I.; Oshuev, D. S.; Publichenko, P. A.; Rakobolskaya, I. V.; Roganova, T. M.; Saito, M.; Sazhina, G. P.; Semba, H.; Shabanova, Yu. N.; Shibata, T.; Sugimoto, H.; Sveshnikova, L. G.; Takahashi, K.; Tsutiya, T.; Taran, V. M.; Yajima, N.; Yamagami, T.; Yamamoto, K.; Yashin, I. V.; Zamchalova, E. A.; Zatsepin, G. T.; Zayarnaya, I. S.

    2001-08-01

    RUssian Nippon JOint Balloon (RUNJOB) has been observing the primary spectra of cosmic ray nuclei since 1995. Data from 6 out of 10 succesful flights will be used to report the spectra of heavy primaries up to iron nucleus with the energy range more than 1014 eV/particle. The details of analysis like charge and energy determinations will be also given.

  9. (abstract) Spectra of Comet Hale-Bopp

    NASA Technical Reports Server (NTRS)

    Hanner, M. S.; Hayward, T. L.; Lynch, D. K.; Russell, R. W.

    1996-01-01

    The spectra of Hale-Bopp were acquired in mid-1996 at R > 3.5 AU. Strong silicate emission is present in all the spectra. The shape of the feature is very similar to that seen in comet P/Halley. This is the first time that a strong silicate feature has been detected in a comet beyond 2 AU.

  10. COMPUTER INTERPRETATION OF POLLUTANT MASS SPECTRA

    EPA Science Inventory

    The objective of this research was to improve systems for computer examination of the mass spectra of unknown pollutants. For this we have developed a new probability based matching (PBM) system for the retrieval of mass spectra from a large data base, and have substantially impr...

  11. High-resolution Visible Spectra of Titan

    NASA Astrophysics Data System (ADS)

    Sim, Chae Kyung; Kim, S.

    2006-09-01

    We have obtained high-resolution (R 30,000) spectra of Titan between 4,000 and 10,000 A on Feb. 23, 2005 (UT) using an optical echelle spectrograph (BOES) on the 1.8-m telescope at Bohyunsan Observatory, Korea. The raw Titan spectra contain telluric and solar absorption/emission lines. We used Kitt Peak solar atlases to remove the solar lines effectively. We also constructed synthetic spectra for the atmosphere of Titan including haze layers and utilizing laboratory spectra of CH4 available in literature. Preliminary results on the identifications of weak CH4 lines and on the derived opacities of the haze layers will be presented. Since the observations were carried out near the activities of Cassini observations of Titan, these high-resolution visible spectra are complementary to Cassini/VIMS imagery.

  12. HST Spatially Resolved Spectra of the Accretion Disc and Gas Stream of the Nova-Like Variable UX Ursae Majoris

    NASA Technical Reports Server (NTRS)

    Baptista, Raymundo; Horne, Keith; Wade, Richard A.; Hubeny, Ivan; Long, Knox S.; Rutten, Rene G. M.

    1998-01-01

    Time-resolved eclipse spectroscopy of the nova-like variable UX UMa obtained with the Hubble Space Telescope/Faint Object Spectrograph (HST/FOS) on 1994 August and November is analysed with eclipse mapping techniques to produce spatially resolved spectra of its accretion disk and gas stream as a function of distance from the disk centre. The inner accretion disk is characterized by a blue continuum filled with absorption bands and lines, which cross over to emission with increasing disk radius, similar to that reported at optical wavelengths. The comparison of spatially resolved spectra at different azimuths reveals a significant asymmetry in the disk emission at ultraviolet (UV) wavelengths, with the disk side closest to the secondary star showing pronounced absorption by an 'iron curtain' and a Balmer jump in absorption. These results suggest the existence of an absorbing ring of cold gas whose density and/or vertical scale increase with disk radius. The spectrum of the infalling gas stream is noticeably different from the disc spectrum at the same radius suggesting that gas overflows through the impact point at the disk rim and continues along the stream trajectory, producing distinct emission down to 0.1 R(sub LI). The spectrum of the uneclipsed light shows prominent emission lines of Lyalpha, N v lambda1241, SiIV Lambda 1400, C IV Lambda 1550, HeII Lambda 1640, and MgII Lambda 2800, and a UV continuum rising towards longer wavelengths. The Balmer jump appears clearly in emission indicating that the uneclipsed light has an important contribution from optically thin gas. The lines and optically thin continuum emission are most probably emitted in a vertically extended disk chromosphere + wind. The radial temperature profiles of the continuum maps are well described by a steady-state disc model in the inner and intermediate disk regions (R greater than or equal to 0.3R(sub LI) ). There is evidence of an increase in the mass accretion rate from August to November

  13. Climatic Spectra of Extreme Sea States

    NASA Astrophysics Data System (ADS)

    Boukhanovsky, A.; Lopatoukhin, L.; Sas'kov, K.

    Climatic variability of sea waves is described in the terms of statistical ensemble of directional spectra, dependent from spatial coordinates (x,y) and time t. The major probabilistic characteristics of the ensemble are the climatic spectra, i.e. spectra ap- propriate to certain wavemaking conditions with certain probability. Traditionally the definition of climatic wave spectra is based on a buoy measurements in a point. How- ever such data are restricted, and are unsuitable for estimation of climatic spectra of extreme waves with return period up to 100 years or longer. Hindcasting of statistical ensemble of spectra by mean of some numerical model allows to expand the informa- tion base significantly. In this report the approach to analysis and synthesis of climatic spectra, corresponding to extreme sea states, is proposed. The Barents sea is consid- ered as an example. A set of 43800 directional spectra of wind sea and swell (1970- 1999, every 6 hours) for any of 565 points of regular grid 0.50x1.50 are calculated. Numerical wave model Wave Watch III for computation on the parallel supercomputer Parsytec CC/20 was used. The NCEP/NCAR reanalysis wind fields were used as input data. Statistical analysis of computed spectra allows to separate a set of genetic types appropriate to various stable sea states. For each of types the system of parameters as discriminant variables are proposed. Probabilistic values of these parameters allows to approximate the probabilistic characteristic of all the spectra ensemble in terms of non-random function of random arguments. It allows to synthesize the results of the analysis in terms of multiscale stochastic model of spectral wave climate, with tak- ing into account the temporal nonstationary and spatial inhomogeneity of wave fields. The Monte-Carlo approach is employed for stochastic simulation. Stochastic simu- lation proves the extrapolation procedure for climatic spectra of rare (extreme) sea states. Specific climatic wave

  14. Use of mutation spectra analysis software.

    PubMed

    Rogozin, I; Kondrashov, F; Glazko, G

    2001-02-01

    The study and comparison of mutation(al) spectra is an important problem in molecular biology, because these spectra often reflect on important features of mutations and their fixation. Such features include the interaction of DNA with various mutagens, the function of repair/replication enzymes, and properties of target proteins. It is known that mutability varies significantly along nucleotide sequences, such that mutations often concentrate at certain positions, called "hotspots," in a sequence. In this paper, we discuss in detail two approaches for mutation spectra analysis: the comparison of mutation spectra with a HG-PUBL program, (FTP: sunsite.unc.edu/pub/academic/biology/dna-mutations/hyperg) and hotspot prediction with the CLUSTERM program (www.itba.mi.cnr.it/webmutation; ftp.bionet.nsc.ru/pub/biology/dbms/clusterm.zip). Several other approaches for mutational spectra analysis, such as the analysis of a target protein structure, hotspot context revealing, multiple spectra comparisons, as well as a number of mutation databases are briefly described. Mutation spectra in the lacI gene of E. coli and the human p53 gene are used for illustration of various difficulties of such analysis. PMID:11180592

  15. SCALING PROPERTIES OF THE TRANSVERSE MASS SPECTRA.

    SciTech Connect

    SCHAFFNER-BIELICH,J.; KHARZEEV,D.; MCLERRAN,L.; VENUGOPALAN,R.

    2002-01-13

    Motivated from the formation of an initial state of gluon-saturated matter, we discuss scaling relations for the transverse mass spectra at BNL's Relativistic Heavy-Ion Collider (RHIC). We show on linear plots, that the transverse mass spectra for various hadrons can be described by an universal function in m{sub t}. The transverse mass spectra for different centralities can be rescaled into each other. Finally, we demonstrate that m{sub t}-scaling is also present in proton-antiproton collider data and compare it to m{sub t}-scaling at RHIC.

  16. Analysis of atmospheric spectra for trace gases

    NASA Technical Reports Server (NTRS)

    Rinsland, Curtis P.; Seals, Robert K., Jr.; Smith, Mary Ann H.; Goldman, Aaron; Murcray, David G.; Murcray, Frank J.

    1990-01-01

    The objective is the comprehensive analysis of high resolution atmospheric spectra recorded in the middle-infrared region to obtain simultaneous measurements of coupled parameters (gas concentrations of key trace constituents, total column amounts, pressure, and temperature) in the stratosphere and upper troposphere. Solar absorption spectra recorded at 0.002 and 0.02 cm exp -1 resolutions with the University of Denver group's balloon-borne, aircraft borne, and ground-based interferometers and 0.005 to 0.01 cm exp -1 resolution solar spectra from Kitt Peak are used in the analyses.

  17. Negative Ion Photoelectron Spectra of Halomethyl Anions

    NASA Astrophysics Data System (ADS)

    Vogelhuber, Kristen M.; Wren, Scott W.; McCoy, Anne B.; Ervin, Kent M.; Lineberger, W. Carl

    2009-06-01

    Halomethyl anions undergo a significant geometry change upon electron photodetachment, resulting in multiple extended vibrational progressions in the photoelectron spectra. The normal mode analysis that successfully models photoelectron spectra when geometry changes are modest is unable to reproduce the experimental data using physically reasonable parameters. A three-dimensional anharmonic coupled-mode analysis was employed to accurately reproduce the observed vibrational structure. We present the 364 nm negative ion photoelectron spectra of the halomethyl anions CHX_2^- and CDX_2^- (X = Cl, Br, I) and report electron affinities, vibrational frequencies, and geometries.

  18. Chromospheric activity and lithium line variations in the spectra of the spotted star LQ Hydrae

    NASA Astrophysics Data System (ADS)

    Flores Soriano, M.; Strassmeier, K. G.; Weber, M.

    2015-03-01

    Context. Although the relationship between lithium abundance in stars and their magnetic activity is commonly accepted, it is still unclear how the different phenomena related to it can increase the amount of Li, reduce its depletion, or be a source of bias for the measurements. Aims: We study the rotational modulation of chromospheric and photospheric parameters of the young, active, single K2 dwarf LQ Hya and their connection with the variability of the Li i 6708 Å line. Methods: A total of 199 high-resolution STELLA spectra and quasi-simultaneous photometry were used to compute effective temperature, gravity, and chromospheric activity indicators such as Hα and Hβ emission, Balmer decrement, and chromospheric electron density, as a function of the rotational phase. The variation of the Li i 6708 Å line was characterized in terms of equivalent width, abundance, and of 6Li/7Li isotopic ratio in the form of line shifts. Results: Photospheric and chromospheric parameters show clear rotational modulation. Effective temperatures and continuum variations reveal a higher concentration of cool spots on the side of the star on which we also detect stronger chromospheric activity. Increased electron densities and the modulation of the He i D3 line suggest that the source of this activity can be a combination of plages and repeated low-intensity flares. The Li line and other temperature-sensitive lines are clearly enhanced by the spots located on the most active side of the star. Li abundances calculated taking into account the temperature variations simultaneously show, although with high dispersion, a small overabundance of this element that correlates well with the surface magnetic activity. In addition, the Li line center is more intensely redshifted than in the other hemisphere, which might be interpreted as a weak enrichment of 6Li. Based on data obtained with the STELLA robotic telescope in Tenerife, an AIP facility jointly operated by AIP and IAC, and the Vienna

  19. Cooperative Interaction Within RNA Virus Mutant Spectra.

    PubMed

    Shirogane, Yuta; Watanabe, Shumpei; Yanagi, Yusuke

    2016-01-01

    RNA viruses usually consist of mutant spectra because of high error rates of viral RNA polymerases. Growth competition occurs among different viral variants, and the fittest clones predominate under given conditions. Individual variants, however, may not be entirely independent of each other, and internal interactions within mutant spectra can occur. Examples of cooperative and interfering interactions that exert enhancing and suppressing effects on replication of the wild-type virus, respectively, have been described, but their underlying mechanisms have not been well defined. It was recently found that the cooperation between wild-type and variant measles virus genomes produces a new phenotype through the heterooligomer formation of a viral protein. This observation provides a molecular mechanism underlying cooperative interactions within mutant spectra. Careful attention to individual sequences, in addition to consensus sequences, may disclose further examples of internal interactions within mutant spectra. PMID:26162566

  20. Microwave spectra of some volatile organic compounds

    NASA Technical Reports Server (NTRS)

    White, W. F.

    1975-01-01

    A computer-controlled microwave (MRR) spectrometer was used to catalog reference spectra for chemical analysis. Tables of absorption frequency, peak absorption intensity, and integrated intensity are included for 26 volatile organic compounds, all but one of which contain oxygen.

  1. Contribution to the study of turbulence spectra

    NASA Technical Reports Server (NTRS)

    Dumas, R.

    1979-01-01

    An apparatus suitable for turbulence measurement between ranges of 1 to 5000 cps and from 6 to 16,000 cps was developed and is described. Turbulence spectra downstream of the grills were examined with reference to their general characteristics, their LF qualities, and the effects of periodic turbulence. Medium and HF are discussed. Turbulence spectra in the boundary layers are similarly examined, with reference to their fluctuations at right angles to the wall, and to lateral fluctuations. Turbulence spectra in a boundary layer with suction to the wall is discussed. Induced turbulence, and turbulence spectra at high Reynolds numbers. Calculations are presented relating to the effect of filtering on the value of the correlations in time and space.

  2. Ultraviolet Spectra of Globular Clusters in Andromeda

    NASA Astrophysics Data System (ADS)

    Peterson, R. C.

    1999-05-01

    As part of a NASA-funded effort with Ben Dorman of Goddard Space Flight Center, I am engaged in calculating spectra from first principles of solar-type stars of a wide range of metallicity. This paper reports on an extension of this work funded by the Hubble Space Telescope archival program, the derivation of fundamental parameters for several globular clusters in Andromeda (M31). Properties of the underlying stellar population are derived by matching archival HST spectra with composite spectra constructed by weighted coaddition of the calculated spectra for stars of appropriate spectral types. Armed with these ab initio calculations, this work explores the degeneracy in age and metallicity in the ultraviolet, and the affect of unknowns such as the relative abundance of light elements versus iron and the possible presence of blue stragglers or blue horizontal branch stars.

  3. Dynamic radio spectra from two fireballs

    NASA Astrophysics Data System (ADS)

    Obenberger, K. S.; Taylor, G. B.; Lin, C. S.; Dowell, J.; Schinzel, F. K.; Stovall, K.

    2015-11-01

    We present dynamic spectra from the Long Wavelength Array telescope of two large meteors (fireballs) observed to emit between 37 and 54 MHz. These spectra show the first ever recorded broadband measurements of this newly discovered VHF emission. The spectra show that the emission is smooth and steep, getting very bright at lower frequencies. We suggest that this signal is possibly emission of Langmuir waves and that these waves could be excited by a bump-on-tail instability within the trail. The spectra of one fireball display broadband temporal frequency sweeps. We suggest that these sweeps are evidence of individual expanding clumps of emitting plasma. While some of these proposed clumps may have formed at the very beginning of the fireball event, others must have formed seconds after the initial event.

  4. Study on Raman spectra of synthetic celluloses

    NASA Astrophysics Data System (ADS)

    Tong, Na; Zhu, Changjun; Zhang, Yixin

    2015-02-01

    Raman spectrometry was employed to study the characteristics of Raman spectra of aliphatic polyamide fiber and polyethylene terephthalate (PET), which were treated with sodium hydroxide, sulfuric acid and copper sulfate, respectively. Raman spectra under different conditions were obtained and the characteristics of the Raman spectra were analyzed. The results show that Raman peaks beyond 1200 cm-1 appear for aliphatic polyamide fiber processed by sodium hydroxide, while the Raman peaks beyond 1000 cm-1 disappear for aliphatic polyamide fiber processed by sulfuric acid. Raman peaks beyond 1750 cm-1 decrease for polyethylene terephthalate processed by sodium hydroxide, while Raman peaks beyond 1000 cm-1 disappear, except weak peaks around 3000 cm-1 , for polyethylene terephthalate processed by sulfuric acid. The variations of the Raman spectra are primarily related to the changes of chemical bonds and molecular structures.

  5. Investigation of Raman spectra of polyethylene terephthalate

    NASA Astrophysics Data System (ADS)

    Zhu, Changjun; Tong, Na; Song, Lixin; Zhang, Guoqing

    2015-08-01

    Raman spectrometry was employed to study the characteristics of Raman spectra of polyethylene terephthalate (PET), which were treated with sodium hydroxide, sulfuric acid and copper sulfate, respectively. Raman spectra under different conditions were obtained and the characteristics of the Raman spectra were analyzed. The morphology structures were observed under different conditions using Atomic Force Microscope. The results show that the spectral intensity of PET treated with sodium hydroxide is higher than that untreated between 200-1750 cm-1, while the intensity of PET treated with sodium hydroxide is lower than that untreated beyond 1750 cm-1 and the fluorescence background of Raman spectra is decreased. The spectral intensity of PET treated with sulfuric acid is remarkably reduced than that untreated, and the intensity of PET treated with copper sulphate is much higher than that untreated.

  6. Comparing Ultraviolet Spectra Against Calculations: First Results

    NASA Technical Reports Server (NTRS)

    Peterson, Ruth C.

    2003-01-01

    The five-year goal of this effort is to calculate high fidelity mid-UV spectra for individual stars and stellar systems for a wide range of ages, abundances, and abundance ratios. In this first year, the emphasis was placed on revising the list of atomic line parameters used to calculate mid-UV spectra. First, new identifications of atomic lines and measurements of their transition probabilities were obtained for lines of the first and second ionization stages of iron-peak elements. Second, observed mid-UV and optical spectra for standard stars were re-analyzed and compared to new calculations, to refine the determination of transition probabilities and to estimate the identity of lines still missing from the laboratory lists. As evidenced by the figures, a dramatic improvement has resulted in the reproduction of the spectra of standard stars by the calculations.

  7. Synthesis and Spectra of Vanadium Complexes.

    ERIC Educational Resources Information Center

    Ophardt, Charles E.; Stupgia, Sean

    1984-01-01

    Describes an experiment which illustrates simple synthetic techniques, redox principles in synthesis reactions, interpretation of visible spectra using Orgel diagrams, and the spectrochemical series. The experiment is suitable for the advanced undergraduate inorganic chemistry laboratory. (JN)

  8. [Spectra of dark green jade from Myanmar].

    PubMed

    Mao, Jian; Chai, Lin-Tao; Guo, Shou-Guo; Fan, Jian-Liang; Bao, Feng

    2013-05-01

    Chemical compositions and spectral characteristics of one type of dark green jades assumed from omphacite jadeite from Myanmar jadeite mining area were studied by X-ray powder diffraction(XRD), X-ray fluorescence spectra(XRF), Raman spectra(RM) and UV-Vis Spectroscopy, etc. Based on testing by XRD and XRF, it was shown that it belongs to iron-enriched plagioclase, including albite and anorthite. The compositions range is between Ab0.731 An0.264 Or0.004 and Ab0.693 An0.303 Or0.004. Raman spectra of samples, albite jade and anorthite were collected and analyzed. Additionally, the distributions of Si, Al in the crystal structure were also discussed. UV-Vis spectra showed that dark green hue of this mineral is associated with d--d electronic transition of Fe3+ and Cr3+. PMID:23905358

  9. POLLUX: a database of synthetic stellar spectra

    NASA Astrophysics Data System (ADS)

    Palacios, A.; Gebran, M.; Josselin, E.; Martins, F.; Plez, B.; Belmas, M.; Lèbre, A.

    2010-06-01

    Aims: Synthetic spectra are needed to determine fundamental stellar and wind parameters of all types of stars. They are also used for the construction of theoretical spectral libraries helpful for stellar population synthesis. Therefore, a database of theoretical spectra is required to allow rapid and quantitative comparisons to spectroscopic data. We provide such a database offering an unprecedented coverage of the entire Hertzsprung-Russell diagram. Methods: We present the POLLUX database of synthetic stellar spectra. For objects with Teff ≤ 6000 K, MARCS atmosphere models are computed and the program TURBOSPECTRUM provides the synthetic spectra. ATLAS12 models are computed for stars with 7000 K ≤ Teff ≤ 15 000 K. SYNSPEC gives the corresponding spectra. Finally, the code CMFGEN provides atmosphere models for the hottest stars (Teff > 25 000 K). Their spectra are computed with CMF_FLUX. Both high resolution (R > 150 000) optical spectra in the range 3000 to 12 000 Å and spectral energy distributions extending from the UV to near-IR ranges are presented. These spectra cover the HR diagram at solar metallicity. Results: We propose a wide variety of synthetic spectra for various types of stars in a format that is compliant with the Virtual Observatory standards. A user-friendly web interface allows an easy selection of spectra and data retrieval. Upcoming developments will include an extension to a large range of metallicities and to the near-IR high resolution spectra, as well as a better coverage of the HR diagram, with the inclusion of models for Wolf-Rayet stars and large datasets for cool stars. The POLLUX database is accessible at http://pollux.graal.univ-montp2.fr/ and through the Virtual Observatory. Copy of database 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

  10. 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.

  11. Electron spectra derived from depth dose distributions.

    PubMed

    Faddegon, B A; Blevis, I

    2000-03-01

    The technique of extracting electron energy spectra from measured distributions of dose along the central axis of clinical electron beams is explored in detail. Clinical spectra measured with this simple spectroscopy tool are shown to be sufficient in accuracy and resolution for use in Monte Carlo treatment planning. A set of monoenergetic depth dose curves of appropriate energy spacing, precalculated with Monte Carlo for a simple beam model, are unfolded from the measured depth dose curve. The beam model is comprised of a point electron and photon source placed in vacuum with a source-to-surface distance of 100 cm. Systematic error introduced by this model affects the calculated depth dose curve by no more than 2%/2 mm. The component of the dose due to treatment head bremsstrahlung, subtracted prior to unfolding, is estimated from the thin-target Schiff spectrum within 0.3% of the maximum total dose (from electrons and photons) on the beam axis. Optimal unfolding parameters are chosen, based on physical principles. Unfolding is done with the public-domain code FERDO. Comparisons were made to previously published spectra measured with magnetic spectroscopy and to spectra we calculated with Monte Carlo treatment head simulation. The approach gives smooth spectra with an average resolution for the 27 beams studied of 16+/-3% of the mean peak energy. The mean peak energy of the magnetic spectrometer spectra was calculated within 2% for the AECL T20 scanning beam accelerators, 3% for the Philips SL25 scattering foil based machine. The number of low energy electrons in Monte Carlo spectra is estimated by unfolding with an accuracy of 2%, relative to the total number of electrons in the beam. Central axis depth dose curves calculated from unfolded spectra are within 0.5%/0.5 mm of measured and simulated depth dose curves, except near the practical range, where 1%/1 mm errors are evident. PMID:10757603

  12. New atlas of IR solar spectra

    NASA Technical Reports Server (NTRS)

    Goldman, A.; Blatherwick, R. D.; Murcray, F. H.; Vanallen, J. W.; Bradford, C. M.; Cook, G. R.; Murcray, D. G.

    1980-01-01

    Over 4500 absorption lines have been marked on the spectra and the corresponding line positions tabulated. The associated absorbing telluric or solar species for more than 90% of these lines have been identified and only a fraction of the unidentified lines have peak absorptions greater than a few percent. The high resolution and the low Sun spectra greatly enhance the sensitivity limits for identification of trace constituents.

  13. Trigonometric Polynomials For Estimation Of Spectra

    NASA Technical Reports Server (NTRS)

    Greenhall, Charles A.

    1990-01-01

    Orthogonal sets of trigonometric polynomials used as suboptimal substitutes for discrete prolate-spheroidal "windows" of Thomson method of estimation of spectra. As used here, "windows" denotes weighting functions used in sampling time series to obtain their power spectra within specified frequency bands. Simplified windows designed to require less computation than do discrete prolate-spheroidal windows, albeit at price of some loss of accuracy.

  14. THE SPITZER ATLAS OF STELLAR SPECTRA (SASS)

    SciTech Connect

    Ardila, David R.; Van Dyk, Schuyler D.; Makowiecki, Wojciech; Stauffer, John; Rho, Jeonghee; Fajardo-Acosta, Sergio; Hoard, D. W.; Wachter, Stefanie; Song, Inseok

    2010-12-15

    We present the Spitzer Atlas of Stellar Spectra, which includes 159 stellar spectra (5-32 {mu}m; R {approx} 100) taken with the Infrared Spectrograph on the Spitzer Space Telescope. This Atlas gathers representative spectra of a broad section of the Hertzsprung-Russell diagram, intended to serve as a general stellar spectral reference in the mid-infrared. It includes stars from all luminosity classes, as well as Wolf-Rayet (WR) objects. Furthermore, it includes some objects of intrinsic interest, such as blue stragglers and certain pulsating variables. All of the spectra have been uniformly reduced, and all are available online. For dwarfs and giants, the spectra of early-type objects are relatively featureless, characterized by the presence of hydrogen lines in A spectral types. Besides these, the most noticeable photospheric features correspond to water vapor and silicon monoxide in late-type objects and methane and ammonia features at the latest spectral types. Most supergiant spectra in the Atlas present evidence of circumstellar gas and/or dust. The sample includes five M supergiant spectra, which show strong dust excesses and in some cases polycyclic aromatic hydrocarbon features. Sequences of WR stars present the well-known pattern of lines of He I and He II, as well as forbidden lines of ionized metals. The characteristic flat-top shape of the [Ne III] line is evident even at these low spectral resolutions. Several Luminous Blue Variables and other transition stars are present in the Atlas and show very diverse spectra, dominated by circumstellar gas and dust features. We show that the [8]-[24] Spitzer colors (IRAC and MIPS) are poor predictors of spectral type for most luminosity classes.

  15. Results from Stacking Grism Spectra of Galaxies at 0.6 < z < 1.2 in the Probing Evolution And Reionization Survey (PEARS)

    NASA Astrophysics Data System (ADS)

    Joshi, Bhavin; Malhotra, Sangeeta; Windhorst, Rogier A.; PEARS team, FIGS team

    2016-06-01

    We present results from median stacking of low-resolution grism spectra for ~1700 galaxies at 0.6 < z < 1.2. The data are from the Probing Evolution And Reionization Survey (PEARS) which is a 200 orbit HST ACS G800L grism survey in GOODS-N and GOODS-S. The visible and near-IR coverage of the grism, 6000A to 9500A, provides rest-frame visible wavelength coverage from ~3000A to ~6000A for the redshift range of our sample. We median stack galaxies of similar rest-frame u-r color and stellar mass by selecting them based on their location in our u-r color vs stellar mass diagram. The grism spectra are stacked in bins of 0.3 in u-r color and 0.5 dex in stellar mass over a range of 0.0 < u-r < 3.0 and 7.0 < log(M) [M_sol] < 11.5 with an average of ~30 galaxies per bin. We find that blue cloud galaxies typically show bluer continua, Balmer breaks and also show H-beta and [OIII] emission lines that are blended together due to the low-resolution of the grism. Red sequence galaxies typically show strong 4000A breaks and redder continua and, at lower significance, also the G-band and Mgb absorption features characteristic of late type stars. We also observe that green valley galaxies, which form ~6% of the total sample, typically show weaker 4000A breaks and relatively flatter continua at wavelengths redder than 4000A.

  16. Background noise spectra of global seismic stations

    SciTech Connect

    Wada, M.M.; Claassen, J.P.

    1996-08-01

    Over an extended period of time station noise spectra were collected from various sources for use in estimating the detection and location performance of global networks of seismic stations. As the database of noise spectra enlarged and duplicate entries became available, an effort was mounted to more carefully select station noise spectra while discarding others. This report discusses the methodology and criteria by which the noise spectra were selected. It also identifies and illustrates the station noise spectra which survived the selection process and which currently contribute to the modeling efforts. The resulting catalog of noise statistics not only benefits those who model network performance but also those who wish to select stations on the basis of their noise level as may occur in designing networks or in selecting seismological data for analysis on the basis of station noise level. In view of the various ways by which station noise were estimated by the different contributors, it is advisable that future efforts which predict network performance have available station noise data and spectral estimation methods which are compatible with the statistics underlying seismic noise. This appropriately requires (1) averaging noise over seasonal and/or diurnal cycles, (2) averaging noise over time intervals comparable to those employed by actual detectors, and (3) using logarithmic measures of the noise.

  17. [Characteristics of Raman Spectra of Polyethylene Terephthalate].

    PubMed

    Tong, Na; Zhu, Chang-jun; Song, Li-xun; Zhang, Chong-hui; Zhang, Guo-qing; Zhang, Yi-xin

    2016-01-01

    Raman spectrometry was employed to study the characteristics of Raman spectra of polyethylene terephthalate (PET), which were treated with sodium hydroxide, sulfuric acid and copper sulfate, respectively. Raman spectra under different conditions were obtained and the characteristics of the Raman spectra were analyzed. The morphology structures were observed under different conditions using Atomic Force Microscope. The results show that the spectral intensity of PET treated with sodium hydroxide is higher than that untreated between 200-1 750 cm(-1), while the intensity of PET treated with sodium hydroxide is lower than that untreated beyond 1 750 cm(-1) and the fluorescence background of Raman spectra is decreased. The spectral intensity of PET treated with sulfuric acid is remarkably reduced than that untreated, and the intensity of PET treated with copper sulphate is much higher than that untreated. The research results obtained by Atomic Force Microscopy show that the variations of the Raman spectra of PET fibers are closely related to. the chemical bonds and molecular structures of PET fibers. The surface of the PET treated with sodium hydroxide is rougher than that untreated, the surface roughness of the PET treated with sulfuric acid is reduced as compared to that untreated, while the surface roughness of the PET treated with copper sulphate is increased. The results obtained by Raman spectroscopy are consistent with those by Atomic Force Microscopy, indicating that the combination of Raman spectroscopy and Atomic Force Microscopy is expected to be a promising characterization technology for polymer characteristics. PMID:27228752

  18. Cleaning HI Spectra Contaminated by GPS RFI

    NASA Astrophysics Data System (ADS)

    Sylvia, Kamin; Hallenbeck, Gregory L.; Undergraduate ALFALFA Team

    2016-01-01

    The NUDET systems aboard GPS satellites utilize radio waves to communicate information regarding surface nuclear events. The system tests appear in spectra as RFI (radio frequency interference) at 1381MHz, which contaminates observations of extragalactic HI (atomic hydrogen) signals at 50-150 Mpc. Test durations last roughly 20-120 seconds and can occur upwards of 30 times during a single night of observing. The disruption essentially renders the corresponding HI spectra useless.We present a method that automatically removes RFI in HI spectra caused by these tests. By capitalizing on the GPS system's short test durations and predictable frequency appearance we are able to devise a method of identifying times containing compromised data records. By reevaluating the remaining data, we are able to recover clean spectra while sacrificing little in terms of sensitivity to extragalactic signals. This method has been tested on 500+ spectra taken by the Undergraduate ALFALFA Team (UAT), in which it successfully identified and removed all sources of GPS RFI. It will also be used to eliminate RFI in the upcoming Arecibo Pisces-Perseus Supercluster Survey (APPSS).This work has been supported by NSF grant AST-1211005.

  19. Spectra from nuclear-excited plasmas

    NASA Technical Reports Server (NTRS)

    De Young, R. J.; Weaver, W. R.

    1980-01-01

    The paper discusses the spectra taken from He-3(n,p)H-3 nuclear-induced plasmas under high thermal neutron flux, lasing conditions. Also, initial spectra are presented for U-235F6 generated plasmas. From an evaluation of these spectra, important atomic and molecular processes that occur in the plasma can be inferred. The spectra presented are the first to be generated by He-3 and U-235F6 nuclear reactions under high neutron flux, lasing conditions. The U-235(n,ff)FF reaction, which liberates 165 MeV of fission-fragment kinetic energy, creates plasmas that are of great interest, since at sufficiently high densities of U-235F6 the gas becomes self-critical; thus, there is no need for an external driving reactor (source of neutrons). The spectra from mixtures of He-3 and Ar, Xe, Kr, Ne, Cl2, F2 and N2 indicate little difference between high-pressure nuclear-induced plasmas and high-pressure electrically pulsed afterglow plasmas for noble-gas systems

  20. EXPLORING THE MORPHOLOGY OF RAVE STELLAR SPECTRA

    SciTech Connect

    Matijevic, G.; Zwitter, T.; Bienayme, O.; Siebert, A.; Bland-Hawthorn, J.; Boeche, C.; Grebel, E. K.; Freeman, K. C.; Gibson, B. K.; Gilmore, G.; Helmi, A.; Munari, U.; Navarro, J.; Parker, Q. A.; Reid, W.; Seabroke, G.; Siviero, A.; Steinmetz, M.; Williams, M.; Watson, F. G.; and others

    2012-06-01

    The RAdial Velocity Experiment (RAVE) is a medium-resolution (R {approx} 7500) spectroscopic survey of the Milky Way that has already obtained over half a million stellar spectra. They present a randomly selected magnitude-limited sample, so it is important to use a reliable and automated classification scheme that identifies normal single stars and discovers different types of peculiar stars. To this end, we present a morphological classification of {approx}350, 000 RAVE survey stellar spectra using locally linear embedding, a dimensionality reduction method that enables representing the complex spectral morphology in a low-dimensional projected space while still preserving the properties of the local neighborhoods of spectra. We find that the majority of all spectra in the database ({approx} 90%-95%) belong to normal single stars, but there is also a significant population of several types of peculiars. Among them, the most populated groups are those of various types of spectroscopic binary and chromospherically active stars. Both of them include several thousands of spectra. Particularly the latter group offers significant further investigation opportunities since activity of stars is a known proxy of stellar ages. Applying the same classification procedure to the sample of normal single stars alone shows that the shape of the projected manifold in two-dimensional space correlates with stellar temperature, surface gravity, and metallicity.

  1. Cloud supersaturations from CCN spectra Hoppel minima

    NASA Astrophysics Data System (ADS)

    Hudson, James G.; Noble, Stephen; Tabor, Samantha

    2015-04-01

    High-resolution cloud condensation nucleus (CCN) spectral measurements in two aircraft field projects, Marine Stratus/Stratocumulus Experiment (MASE) and Ice in Clouds Experiment-Tropical (ICE-T), often showed bimodality that had previously been observed in submicrometer aerosol size distributions obtained by differential mobility analyzers. However, a great deal of spectral shape variability from very bimodal to very monomodal was observed in close proximity. Cloud supersaturation (S) estimates based on critical S, Sc, at minimal CCN concentrations between two modes (Hoppel minima) were ascertained for 63% of 325 measured spectra. These cloud S were lower than effective S (Seff) determined by comparing ambient CCN spectra with nearby cloud droplet concentrations (Nc). Averages for the polluted MASE stratus were 0.15 and 0.23% and for the cumulus clouds of ICE-T 0.44 and 1.03%. This cloud S disagreement between the two methods might in part be due to the fact that Hoppel minima include the effects of cloud processing, which push CCN spectra toward lower S. Furthermore, there is less cloud processing by the smaller cloud droplets, which might be related to smaller droplets evaporating more readily. Significantly lower concentrations within the more bimodal spectra compared with the monomodal spectra indicated active physical processes: Brownian capture of interstitial CCN and droplet coalescence. Chemical cloud processing also contributed to bimodality, especially in MASE.

  2. [Infrared and Raman spectra study on Tianhuang].

    PubMed

    Liu, Yun-gui; Chen, Tao

    2012-08-01

    The Tianhuang stones, from Shoushan in China, were studied by using X-ray powder diffractometry (XRD), infrared (IR) spectroscopy and Raman spectroscopy to obtain the spectra characterization. Wave numbers 3621, 3629 and 3631 cm(-1) in the IR spectra and 3626, 3627 and 3632 cm(-1) in the Raman spectra are the characteristic peaks of dickitic Tianhuang, nacritic Tianhuang and illitic Tianhuang, respectively. Raman spectra assigned to OH are in good agreement with the IR results at 3550 -3750 cm(-1). Dickitic Tianhuang includes ordered dickite and disordered dickite. Compared with ordered dickite, the band assigned to OH3 of disordered dickite shifts to low-frequency by 8 cm(-1) and the relative intensity becomes stronger. The disorder structure may relate to the high level of Fe. The IR absorption spectra of nacritic Tianhuang superimposes strong peaks of dickite, indicating that IR absorption bands of dickite are stronger than that of nacrite at 3550-3750 cm(-1). The main mineral composition of illitic Tianhuang is 2M(1), while illite Tianhuang contains a small amount of 1M. All these characters provide a theoretical basis for the scientific identification of Tianhuang. PMID:23156769

  3. 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.

  4. Inertial solvation in femtosecond 2D spectra

    NASA Astrophysics Data System (ADS)

    Hybl, John; Albrecht Ferro, Allison; Farrow, Darcie; Jonas, David

    2001-03-01

    We have used 2D Fourier transform spectroscopy to investigate polar solvation. 2D spectroscopy can reveal molecular lineshapes beneath ensemble averaged spectra and freeze molecular motions to give an undistorted picture of the microscopic dynamics of polar solvation. The transition from "inhomogeneous" to "homogeneous" 2D spectra is governed by both vibrational relaxation and solvent motion. Therefore, the time dependence of the 2D spectrum directly reflects the total response of the solvent-solute system. IR144, a cyanine dye with a dipole moment change upon electronic excitation, was used to probe inertial solvation in methanol and propylene carbonate. Since the static Stokes' shift of IR144 in each of these solvents is similar, differences in the 2D spectra result from solvation dynamics. Initial results indicate that the larger propylene carbonate responds more slowly than methanol, but appear to be inconsistent with rotational estimates of the inertial response. To disentangle intra-molecular vibrations from solvent motion, the 2D spectra of IR144 will be compared to the time-dependent 2D spectra of the structurally related nonpolar cyanine dye HDITCP.

  5. H. N. Russell and Atomic Spectra

    NASA Astrophysics Data System (ADS)

    Devorkin, David

    2001-04-01

    “I would rather analyze spectra than do cross-word puzzles or do almost anything else” Henry Norris Russell wrote to William F. Meggers in 1927. Meggers, chief of the spectroscopy division at the NBS, had been surprised that an astrophysicist could be so keen about the analysis of complex spectra. But Russell was a new type of astrophysicist, one who made physics the core of his research. Spectra, for Russell, held the "master key" to knowledge about the universe, and of the atom. He was first attracted by the challenge of detecting and explaining anomalies, which he hoped would lead to new knowledge about the structure of matter. Then, influenced by physicists such as Meggers, he devoted himself to filling in the picture of the structure of atoms from their characteristic spectra as completely as possible. In this talk I will review how Russell worked with Meggers and became the nucleus of an ever-widening circle of spectroscopists devoted to the analysis of complex spectra.

  6. Disk-averaged synthetic spectra of Mars.

    PubMed

    Tinetti, Giovanna; Meadows, Victoria S; Crisp, David; Fong, William; Velusamy, Thangasamy; Snively, Heather

    2005-08-01

    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. PMID:16078866

  7. The energy spectra of solar energetic particles

    NASA Technical Reports Server (NTRS)

    Mcguire, R. E.; Von Rosenvinge, T. T.

    1984-01-01

    A survey of recent results on the shapes and relative slopes of the spectra of various solar energetic particle populations is presented, with emphasis on the more extensive results currently available for protons, alphas and electrons. From previous work, it is found that proton spectra 0.8 to more than 400 MeV and alpha spectra 1.4 to 80 MeV/nucleon are best characterized, on average, by a functional form involving a Bessel function in momentum/nucleon. However, proton and alpha spectral slopes using this form are not equal, and there is significant variation from event to event. From other studies, electrons 0.02 to 20 MeV are also found to have curved spectra, but seem to be better fit with a double power law in energy. The spectral properties in both cases correlate with other measures of solar particle acceleration; e.g. gamma-ray line production, hard X-ray burst spectra and microwave fluxes.

  8. Degradation spectra of electrons in the ionosphere

    NASA Astrophysics Data System (ADS)

    Konovalov, V. P.; Son, E. E.

    2015-11-01

    Theory and numerical simulations of degradation spectra of electrons in gases are presented. Theory is based on the power spectra of degradation charged particles as the spectra with fluxes in energy space. Numerical calculations of the electron energy distribution function have been performed for ionospheric gas mixtures constituted of molecules N2, O2 and atom O under influence of high energy electron source with detailed elementary electron collision processes with molecules and atoms being taken into consideration. The energy expenses of electrons into ionization, dissociation and excitation of various levels have been obtained so that to determine the rates of electron collision processes. The dependence of the electron energy expenses into various inelastic electronic processes upon the energy of primary electron source has been revealed. The results are presented for the rates of numerous elementary processes of electron interaction with basic ionospheric components to be suitably determined.

  9. Quantitative analysis of NMR spectra with chemometrics

    NASA Astrophysics Data System (ADS)

    Winning, H.; Larsen, F. H.; Bro, R.; Engelsen, S. B.

    2008-01-01

    The number of applications of chemometrics to series of NMR spectra is rapidly increasing due to an emerging interest for quantitative NMR spectroscopy e.g. in the pharmaceutical and food industries. This paper gives an analysis of advantages and limitations of applying the two most common chemometric procedures, Principal Component Analysis (PCA) and Multivariate Curve Resolution (MCR), to a designed set of 231 simple alcohol mixture (propanol, butanol and pentanol) 1H 400 MHz spectra. The study clearly demonstrates that the major advantage of chemometrics is the visualisation of larger data structures which adds a new exploratory dimension to NMR research. While robustness and powerful data visualisation and exploration are the main qualities of the PCA method, the study demonstrates that the bilinear MCR method is an even more powerful method for resolving pure component NMR spectra from mixtures when certain conditions are met.

  10. Fast Inversion of Solar Ca II Spectra

    NASA Astrophysics Data System (ADS)

    Beck, C.; Choudhary, D. P.; Rezaei, R.; Louis, R. E.

    2015-01-01

    We present a fast (Lt1 s per profile) inversion code for solar Ca II lines. The code uses an archive of spectra that are synthesized prior to the inversion under the assumption of local thermodynamic equilibrium (LTE). We show that it can be successfully applied to spectrograph data or more sparsely sampled spectra from two-dimensional spectrometers. From a comparison to a non-LTE inversion of the same set of spectra, we derive a first-order non-LTE correction to the temperature stratifications derived in the LTE approach. The correction factor is close to unity up to log τ ~ -3 and increases to values of 2.5 and 4 at log τ = -6 in the quiet Sun and the umbra, respectively.

  11. Ultraviolet spectra and chromospheres of R stars

    NASA Technical Reports Server (NTRS)

    Eaton, J. A.; Johnson, H. R.; Obrien, G. T.; Baumert, J. H.

    1985-01-01

    Long-wavelength IUE spectra of 13 normal R stars and two hydrogen-deficient R0 supergiants were obtained. Early R stars are noted to have line spectra and levels of flux in the ultraviolet characteristic of G5-K2 III stars, whereas late R stars were observed to have colors and line spectra similar to late K and M stars, but with greatly enhanced strength of low-lying multiplets of neutral metals. Hydrogen-deficient carbon stars show readily apparent differences from the normal early R stars, reflecting their luminosity and somewhat higher temperatures. The lines of neutral metals in these stars are weakened, while those of ionized metals are strengthened.

  12. Synthetic spectra: a tool for correlation spectroscopy

    SciTech Connect

    Sinclair, Michael B.; Butler, Michael A.; Ricco, Anthony J. Senturia, Stephen D.

    1997-05-01

    We show that computer-generated diffractive optical elements can be used to synthesize the infrared spectra of important compounds, and we describe a modified phase-retrieval algorithm useful for the design of elements of this type. In particular, we present the results of calculations of diffractive elements that are capable of synthesizing portions of the infrared spectra of gaseous hydrogen fluoride (HF) and trichloroethylene (TCE). Further, we propose a new type of correlation spectrometer that uses these diffractive elements rather than reference cells for the production of reference spectra. Storage of a large number of diffractive elements, each producing a synthetic spectrum corresponding to a different target compound, in compact-disk-like format will allow a spectrometer of this type to rapidly determine the composition of unknown samples. Other advantages of the proposed correlation spectrometer are also discussed. {copyright} 1997 Optical Society of America

  13. Crystal field spectra of lunar pyroxenes.

    NASA Technical Reports Server (NTRS)

    Burns, R. G.; Abu-Eid, R. M.; Huggins, F. E.

    1972-01-01

    Absorption spectra in the visible and near infrared regions have been obtained for pyroxene single crystals in rocks from the Apollo 11, 12, 14, and 15 missions. The polarized spectra are compared with those obtained from terrestrial calcic clinopyroxenes, subcalcic augites, pigeonites, and orthopyroxenes. The lunar pyroxenes contain several broad, intense absorption bands in the near infrared, the positions of which are related to bulk composition, Fe(2+) site occupancy and structure type of the pyroxene. The visible spectra contain several sharp, weak peaks mainly due to spin-forbidden transitions in Fe(2+). Additional weak bands in this region in Apollo 11 pyroxenes are attributed to Ti(3+) ions. Spectral features from Fe(3+), Mn(2+), Cr(3+), and Cr(2+) were not observed.

  14. On the Individuality of Sleep EEG Spectra

    PubMed Central

    Lewandowski, Achim; Rosipal, Roman; Dorffner, Georg

    2013-01-01

    Research in recent years has supported the hypothesis that many properties of the electroencephalogram (EEG) are specific to an individual. In this study, the intra- and inter-individual variations of sleep EEG signals were investigated. This was carried out by analyzing the stability of the average EEG spectra individually computed for the Rechtschaffen and Kales (RK) sleep stages. Six EEG channels were used to account for the topographical aspect of the analysis. Validity of the results was supported by considering a wide dataset of 174 subjects with normal sleep. Subjects spent two consecutive nights in the sleep laboratory during which EEG recordings were obtained. High similarity between average spectra of two consecutive nights was found considering an individual. More than 89% of the second night recordings were correctly assigned to their counterparts of the first night. The average spectra of sleep EEG computed for each RK sleep stage have shown a high degree of individuality. PMID:23997385

  15. FAST INVERSION OF SOLAR Ca II SPECTRA

    SciTech Connect

    Beck, C.; Choudhary, D. P.; Rezaei, R.; Louis, R. E.

    2015-01-10

    We present a fast (<<1 s per profile) inversion code for solar Ca II lines. The code uses an archive of spectra that are synthesized prior to the inversion under the assumption of local thermodynamic equilibrium (LTE). We show that it can be successfully applied to spectrograph data or more sparsely sampled spectra from two-dimensional spectrometers. From a comparison to a non-LTE inversion of the same set of spectra, we derive a first-order non-LTE correction to the temperature stratifications derived in the LTE approach. The correction factor is close to unity up to log τ ∼ –3 and increases to values of 2.5 and 4 at log τ = –6 in the quiet Sun and the umbra, respectively.

  16. Red spectra from white and blue noise

    PubMed Central

    Balmforth, N. J.; Provenzale, A.; Spiegel, E. A.; Martens, M.; Tresser, C.; Wu, C. W.

    1999-01-01

    The value of maps of the interval in modelling population dynamics has recently been called into question because temporal variations from such maps have blue or white power spectra, whereas many observations of real populations show time-series with red spectra. One way to deal with this discrepancy is to introduce chaotic or stochastic fluctuations in the parameters of the map. This leads to on–off intermittency and can markedly redden the spectrum produced by a model that does not by itself have a red spectrum. The parameter fluctuations need not themselves have a red spectrum in order to achieve this effect. Because the power spectrum is not invariant under a change of variable, another way to redden the spectrum is by a suitable transformation of the variables used. The question this poses is whether spectra are the best means of characterizing a fluctuating variable.

  17. POLLUX: a database of stellar spectra - First step : SED and High Resolution Synthetic Spectra

    NASA Astrophysics Data System (ADS)

    Palacios, A.; Josselin, E.; Lèbre, A.; Martins, F.; Monier, R.; Plez, B.; Belmas, M.

    2008-10-01

    POLLUX is a stellar spectra database under development at the GRAAL laboratory (Montpellier, France). It will be made available on-line to the community through a VO compliant interface (http://pollux.graal.univ-montp2.fr). In its first version, POLLUX will propose theoretical data: high resolution synthetic spectra and spectral energy distribution.

  18. Interpretation of IR Spectra of Indolinospirobenzothiopyran

    NASA Astrophysics Data System (ADS)

    Gladkov, L. L.; Khamchukov, Yu. D.; Sychev, I. Yu.; Lyubimov, A. V.; Gladkova, G. A.

    2015-09-01

    The structures of four stereomers (enantiomers) of photochromic indolinospirobenzothiopyran (ISTP) in the closed form were studied by the DFT method. The most stable structure was found. IR spectra of ISTP in KBr pellets and as a film on single-crystalline KBr plates (in the region 400-4000 cm -1 ) and as a powder between polyethylene plates (100-400 cm -1 ) were measured. An interpretation of the obtained IR spectra was proposed. Specific features of normal modes of ISTP caused by the presence of the spiro center were revealed.

  19. What can we learn from inclusive spectra

    SciTech Connect

    Nagamiya, S.

    1981-05-01

    The present experimental status on single particle inclusive measurements is described. Then, the geometrical aspect of the collision is discussed from the data of total integrated cross sections of nuclear charge or mass. The dynamical aspect of the collision, especially that for the participating region is discussed in connection with proton spectra, composite fragment spectra, pion production, ratios of ..pi../sup -//..pi../sup +/, n/p and t//sup 3/He, and production of strange particles. The spectator physics is described from the data on projectile fragments. (GHT)

  20. AIS-2 spectra of California wetland vegetation

    NASA Technical Reports Server (NTRS)

    Gross, Michael F.; Ustin, Susan L.; Klemas, Vytautas

    1987-01-01

    Spectral data gathered by Airborne Imaging Spectrometers-2 from wetlands were analyzed. Spectra representing stands of green Salicornia virginica, green Sesuvium verrucosum, senescing Distichlis spicata, a mixture of senescing Scirpus acutus and Scirpus californicus, senescing Scirpus paludosus, senescent S. paludosus, mowed senescent S. paludosus, and soil were isolated. No difference among narrowband spectral reflectance of the cover types was apparent between 0.8 to 1.6 micron. There were, however, broadband differences in brightness. These differences were sufficient to permit a fairly accurate decomposition of the image into its major cover type components using a procedure that assumes an additive linear mixture of surface spectra.

  1. 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.

  2. Augmentation of ENDF/B fission product gamma-ray spectra by calculated spectra

    SciTech Connect

    Katakura, J. ); England, T.R. )

    1991-11-01

    Gamma-ray spectral data of the ENDF/B-V fission product decay data file have been augmented by calculated spectra. The calculations were performed with a model using beta strength functions and cascade gamma-ray transitions. The calculated spectra were applied to individual fission product nuclides. Comparisons with several hundred measured aggregate gamma spectra after fission were performed to confirm the applicability of the calculated spectra. The augmentation was extended to a preliminary ENDF/B-VI file, and to beta spectra. Appendix C provides information on the total decay energies for individual products and some comparisons of measured and aggregate values based on the preliminary ENDF/B-VI files. 15 refs., 411 figs.

  3. 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.

  4. Squeezing spectra for nonlinear optical systems

    NASA Technical Reports Server (NTRS)

    Collett, M. J.; Walls, D. F.

    1985-01-01

    The squeezing spectra for the output fields of several intracavity nonlinear optical systems are obtained. It is shown that at critical points, e.g., the turning points for optical bistability, the threshold for parametric oscillation, and the self-pulsing instability in second-harmonic generation, perfect squeezing in the output field is, in principle, possible.

  5. Principal component analysis of phenolic acid spectra

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phenolic acids are common plant metabolites that exhibit bioactive properties and have applications in functional food and animal feed formulations. The ultraviolet (UV) and infrared (IR) spectra of four closely related phenolic acid structures were evaluated by principal component analysis (PCA) to...

  6. Microdosimetric spectra measurements of JANUS neutrons

    SciTech Connect

    Marshall, I.R.; Williamson, F.S.

    1985-01-01

    Neutron radiation from the JANUS reactor at Argonne National Laboratory is being used with increasing frequency for major biological experiments. The fast neutron spectrum has a Kerma-weighted mean energy of 0.8 MeV and low gamma-ray contamination. In 1984 the JANUS fission converter plate of highly enriched uranium was replaced by one made of low-enriched uranium. We recorded microdosimetric spectra at several different positions in the high-flux irradiation room of JANUS before the change of the converter plate. Each set of measurements consisted of spectra taken at three different site diameters (0.5, 1.0, and 5.0 ..mu..m) and in both ''attenuator up'' and ''attenuator down'' configurations. At two conventional dosimetry reference positions, two sets of measurements were recorded. At three biological reference positions, measurements simulating several biological irradiation conditions, were taken. The dose rate at each position was estimated and compared with dose rates obtained previously by conventional dosimetry. Comparison of the different measurements showed no major change in spectra as a function of position or irradiation condition. First results from similar sets of measurements recorded after the installment of the new converter plate indicate no major change in the spectra. 11 refs., 4 figs., 5 tabs.

  7. Limitation of energetic ring current ion spectra

    NASA Astrophysics Data System (ADS)

    Summers, Danny; Shi, Run

    2015-09-01

    We address the problem of determining the limiting energetic ring current ion spectrum resulting from electromagnetic ion cyclotron (EMIC)-wave-ion interactions. We solve the problem in a relativistic regime, incorporating a cold background multi-ion plasma component and without assuming a predetermined form for the ion energy distribution. The limiting (Kennel-Petschek) spectrum is determined by the condition that the EMIC waves acquire a specified gain over a given convective length scale for all frequencies over which wave growth occurs. We find that the limiting ion spectrum satisfies an integral equation that must be solved numerically. However, at large particle energy E, the limiting spectrum takes the simple form J ∝ 1/E, E → ∞. Moreover, this 1/E spectral shape does not depend on the energetic ion in question nor on the background multi-ion plasma composition. We provide numerical solutions for the limiting spectra for Earth-like parameters. In addition, at four planets, Jupiter, Saturn, Uranus, and Neptune, we compare measured ion spectra with corresponding numerical limiting spectra. This paper parallels an earlier analogous study on the limitation of radiation belt electron spectra by whistler mode wave-electron interactions.

  8. Acceleration spectra for subduction zone earthquakes

    USGS Publications Warehouse

    Boatwright, J.; Choy, G.L.

    1989-01-01

    We estimate the source spectra of shallow earthquakes from digital recordings of teleseismic P wave groups, that is, P+pP+sP, by making frequency dependent corrections for the attenuation and for the interference of the free surface. The correction for the interference of the free surface assumes that the earthquake radiates energy from a range of depths. We apply this spectral analysis to a set of 12 subduction zone earthquakes which range in size from Ms = 6.2 to 8.1, obtaining corrected P wave acceleration spectra on the frequency band from 0.01 to 2.0 Hz. Seismic moment estimates from surface waves and normal modes are used to extend these P wave spectra to the frequency band from 0.001 to 0.01 Hz. The acceleration spectra of large subduction zone earthquakes, that is, earthquakes whose seismic moments are greater than 1027 dyn cm, exhibit intermediate slopes where u(w)???w5/4 for frequencies from 0.005 to 0.05 Hz. For these earthquakes, spectral shape appears to be a discontinuous function of seismic moment. Using reasonable assumptions for the phase characteristics, we transform the spectral shape observed for large earthquakes into the time domain to fit Ekstrom's (1987) moment rate functions for the Ms=8.1 Michoacan earthquake of September 19, 1985, and the Ms=7.6 Michoacan aftershock of September 21, 1985. -from Authors

  9. Raman phonon spectra of pentacene polymorphs

    NASA Astrophysics Data System (ADS)

    Brillante, A.; Della Valle, R. G.; Farina, L.; Girlando, A.; Masino, M.; Venuti, E.

    2002-05-01

    We report for the first time lattice phonon Raman spectra of pentacene measured by means of a Raman microprobe technique. We experimentally prove the existence of two polymorphs, as expected from recent structural studies. A comparison with Quasi Harmonic Lattice Dynamics calculations, previously performed starting from the available X-ray data, help us in identifying the phase to which each crystal belongs.

  10. Temporal Evolution of Solar Energetic Particle Spectra

    NASA Astrophysics Data System (ADS)

    Doran, Donald J.; Dalla, Silvia

    2016-08-01

    During solar flares and coronal mass ejections, Solar Energetic Particles (SEPs) may be released into the interplanetary medium and near-Earth locations. The energy spectra of SEP events at 1 AU are typically averaged over the entire event or studied in a few snapshots. In this article we analyze the time evolution of the energy spectra of four large selected SEP events using a large number of snapshots. We use a multi-spacecraft and multi-instrument approach for the observations, obtained over a wide SEP energy range. We find large differences in the spectra at the beginning of the events as measured by different instruments. We show that over time, a wave-like structure is observed traveling through the spectra from the highest energies to the lowest energies, creating an "arch" shape that then straightens into a power law later in the event, after times on the order of 10 hours. We discuss the processes that determine SEP intensities and their role in shaping the spectral time evolution.

  11. Scattering Spectra of Single Gold Nanoshells

    NASA Astrophysics Data System (ADS)

    Hafner, Jason H.; Nehl, Colleen L.; Goodrich, Glenn P.; Tam, Felicia; Halas, Naomi J.

    2004-03-01

    Gold nanoshells are metal coated silica nanoparticles whose plasmon resonances vary from the visible to IR depending on their core to shell thickness ratio. Monodisperse nanoshell solutions can be synthesized such that their absorbance spectra match the calculated extinction spectra for the corresponding nanoshell structure. Using transmitted light dark field illumination and high numerical aperture optics, we have studied the scattering spectra of single gold nanoshells supported on ITO substrates in an optically homogeneous medium. With the aid of alignment marks, the same nanoshell can then be structurally characterized by electron microscopy. We have used this system to investigate the lineshape of single nanoshell scattering spectra to further elucidate the relative contributions of retardation, electron-interface scattering, and structural inhomogeneity. [1] Single particle measurements also facilitate the observation subtle interparticle and particle-substrate hybridization effects. [2] [1] S. L. Westcott, J. B. Jackson, C. Radloff, N. J. Halas, Phys. Rev. B 66, 155431 (2002). [2] E. Prodan, C. Radloff, N. J. Halas, P. Nordlander, Science 302, 419-422 (2003).

  12. Absorption spectra of cold dilute solid solutions

    SciTech Connect

    Holland, R.F.; Maier, W.B. II; Freund, S.; Beattie, W.H.

    1983-06-01

    Infrared absorption spectra have been obtained for some compounds trapped in crystalline solids by freezing liquid Xe, Kr, Ar, or CH/sub 4/ solutions. The optical quality of the solid solutions is good, and they have been cooled to approx.80 K in 1.35 cm sample thicknesses to study the absorption in fundamental vibrational bands of the solutes. In the cases discussed, the bands are narrow, with observed full widths at half-maximum absorbance 0.05--0.30 cm/sup -1/ greater than the instrumental resolution (0.18--0.29 cm/sup -1/). The spectra appear to be free of ''multiple site'' and solute aggregate absorptions. Spectra displaying isotropic splitting in bands of natural BCl/sub 3/, SeF/sub 6/, OsO/sub 4/, TiCl/sub 4/, and MoF/sub 6/ are presented, and band frequencies are compared with some results obtained in evaporative matrices, in the gas phase, and in liquid solutions. For this comparison we have obtained some spectra of SeF/sub 6/ and BCl/sub 3/ gas.

  13. Discriminating Dysarthria Type from Envelope Modulation Spectra

    ERIC Educational Resources Information Center

    Liss, Julie M.; LeGendre, Sue; Lotto, Andrew J.

    2010-01-01

    Purpose: Previous research demonstrated the ability of temporally based rhythm metrics to distinguish among dysarthrias with different prosodic deficit profiles (J. M. Liss et al., 2009). The authors examined whether comparable results could be obtained by an automated analysis of speech envelope modulation spectra (EMS), which quantifies the…

  14. Variations on supersymmetry breaking and neutrino spectra

    SciTech Connect

    Borzumati, F.; Hamaguchi, K.; Nomura, Y.; Yanagida, T.

    2000-12-11

    The problem of generating light neutrinos within supersymmetric models is discussed. It is shown that the hierarchy of scales induced by supersymmetry breaking can give rise to suppression factors of the correct order of magnitude to produce experimentally allowed neutrino spectra.

  15. Correlation Functions Aid Analyses Of Spectra

    NASA Technical Reports Server (NTRS)

    Beer, Reinhard; Norton, Robert H., Jr.

    1989-01-01

    New uses found for correlation functions in analyses of spectra. In approach combining elements of both pattern-recognition and traditional spectral-analysis techniques, spectral lines identified in data appear useless at first glance because they are dominated by noise. New approach particularly useful in measurement of concentrations of rare species of molecules in atmosphere.

  16. Analysis of COSIMA spectra: Bayesian approach

    NASA Astrophysics Data System (ADS)

    Lehto, H. J.; Zaprudin, B.; Lehto, K. M.; Lönnberg, T.; Silén, J.; Rynö, J.; Krüger, H.; Hilchenbach, M.; Kissel, J.

    2015-06-01

    We describe the use of Bayesian analysis methods applied to time-of-flight secondary ion mass spectrometer (TOF-SIMS) spectra. The method is applied to the COmetary Secondary Ion Mass Analyzer (COSIMA) TOF-SIMS mass spectra where the analysis can be broken into subgroups of lines close to integer mass values. The effects of the instrumental dead time are discussed in a new way. The method finds the joint probability density functions of measured line parameters (number of lines, and their widths, peak amplitudes, integrated amplitudes and positions). In the case of two or more lines, these distributions can take complex forms. The derived line parameters can be used to further calibrate the mass scaling of TOF-SIMS and to feed the results into other analysis methods such as multivariate analyses of spectra. We intend to use the method, first as a comprehensive tool to perform quantitative analysis of spectra, and second as a fast tool for studying interesting targets for obtaining additional TOF-SIMS measurements of the sample, a property unique to COSIMA. Finally, we point out that the Bayesian method can be thought of as a means to solve inverse problems but with forward calculations, only with no iterative corrections or other manipulation of the observed data.

  17. Vibrational Spectra of γ-Aminobutyric Acid

    NASA Astrophysics Data System (ADS)

    Suresh, D. M.; Sajan, D.; Laladas, K. P.; Joe, I. Hubert; Jayakumar, V. S.

    2008-11-01

    The NIR-FT Raman, FT-IR spectral analysis of γ-Aminobutyric acid (GABA) a simple amino acid is carried out by density functional computations. The vibrational spectra confirm the existence of NH3+ in GABA. Hydroxyl groups H-bonded to the different extents are analysed, supported by computed results.

  18. EEG Power Spectra of Adolescent Poor Readers.

    ERIC Educational Resources Information Center

    Ackerman, Peggy T.; McPherson, W. Brian; Oglesby, D. Michael; Dykman, Roscoe A.

    1998-01-01

    Electroencephalographic power spectra were studied in two poor-reading adolescent groups (n=38), dysphonetic and phonetic. Significant Group x Hemisphere effects were found in the alpha and beta bands, with the phonetic group showing right greater than left asymmetry. Results suggest more circumscribed and mature processing in the phonetically…

  19. Silicon Carbide: The Problem with Laboratory Spectra

    NASA Astrophysics Data System (ADS)

    Speck, A. K.; Hofmeister, A. M.; Barlow, M. J.

    2000-03-01

    The interpretation of astronomical observations of infrared (IR) silicon carbide (SiC) features in the spectra of carbon stars have revealed discrepancies between the work of astronomers and that of meteoriticists. The silicon carbide observed around carbon stars has been attributed to one type of SiC (α) while meteoritic samples believed to have formed around such stars are of another type of SiC (β). The key to solving this problem has been to understand the sources of laboratory data used by astronomers in order to interpret the IR spectra. Through comparison of thin film IR absorption spectra and spectra taken using finely ground samples dispersed in potassium bromide (KBr) pellets we show that the previously invoked ``KBr matrix-correction'' is unnecessary for powder dispersions obtained from very fine grain sizes of SiC. Comparison of our data and previous measurements show that dust around carbon stars is β-SiC, consistent with laboratory studies of presolar grains in meteorites. The implications of these findings affect twenty years of work. The IR spectroscopic laboratory data used by astronomers to identify dust species in space must be carefully scrutinized to ensure that the KBr correction is not responsible for further misattributions of minerals in astronomical dust features.

  20. Chaotic spectra: How to extract dynamic information

    SciTech Connect

    Taylor, H.S.; Gomez Llorente, J.M.; Zakrzewski, J.; Kulander, K.C.

    1988-10-01

    Nonlinear dynamics is applied to chaotic unassignable atomic and molecular spectra with the aim of extracting detailed information about regular dynamic motions that exist over short intervals of time. It is shown how this motion can be extracted from high resolution spectra by doing low resolution studies or by Fourier transforming limited regions of the spectrum. These motions mimic those of periodic orbits (PO) and are inserts into the dominant chaotic motion. Considering these inserts and the PO as a dynamically decoupled region of space, resonant scattering theory and stabilization methods enable us to compute ladders of resonant states which interact with the chaotic quasi-continuum computed in principle from basis sets placed off the PO. The interaction of the resonances with the quasicontinuum explains the low resolution spectra seen in such experiments. It also allows one to associate low resolution features with a particular PO. The motion on the PO thereby supplies the molecular movements whose quantization causes the low resolution spectra. Characteristic properties of the periodic orbit based resonances are discussed. The method is illustrated on the photoabsorption spectrum of the hydrogen atom in a strong magnetic field and on the photodissociation spectrum of H/sub 3//sup +/. Other molecular systems which are currently under investigation using this formalism are also mentioned. 53 refs., 10 figs., 2 tabs.

  1. Prompt fission neutron spectra of actinides

    DOE PAGESBeta

    Capote, R.; Chen, Y. -J.; Hambsch, F. -J.; Kornilov, N. V.; Lestone, J. P.; Litaize, O.; Morillon, B.; Neudecker, D.; Oberstedt, S.; Ohsawa, T.; et al

    2016-01-06

    Here, the energy spectrum of prompt neutrons emitted in fission (PFNS) plays a very important role in nuclear science and technology. A Coordinated Research Project (CRP) "Evaluation of Prompt Fission Neutron Spectra of Actinides" was established by the IAEA Nuclear Data Section in 2009, with the major goal to produce new PFNS evaluations with uncertainties for actinide nuclei.

  2. Rest-Frame Optical Spectra of Three Strongly Lensed Galaxies at z ~ 2

    NASA Astrophysics Data System (ADS)

    Hainline, Kevin N.; Shapley, Alice E.; Kornei, Katherine A.; Pettini, Max; Buckley-Geer, Elizabeth; Allam, Sahar S.; Tucker, Douglas L.

    2009-08-01

    We present Keck II NIRSPEC rest-frame optical spectra for three recently discovered lensed galaxies: the Cosmic Horseshoe (z = 2.38), the Clone (z = 2.00), and SDSS J090122.37+181432.3 (z = 2.26). The boost in signal-to-noise ratio (S/N) from gravitational lensing provides an unusually detailed view of the physical conditions in these objects. A full complement of high S/N rest-frame optical emission lines is measured, spanning from rest frame 3600 to 6800 Å, including robust detections of fainter lines such as Hγ, [S II]λ6717,6732, and in one instance [Ne III]λ3869. SDSS J090122.37+181432.3 shows evidence for active galactic nucleus activity, and therefore we focus our analysis on star-forming regions in the Cosmic Horseshoe and the Clone. For these two objects, we estimate a wide range of physical properties. Current lensing models for the Cosmic Horseshoe and the Clone allow us to correct the measured Hα luminosity and calculated star formation rate. Metallicities have been estimated with a variety of indicators, which span a range of values of 12+ log(O/H) = 8.3-8.8, between ~0.4 and ~1.5 of the solar oxygen abundance. Dynamical masses were computed from the Hα velocity dispersions and measured half-light radii of the reconstructed sources. A comparison of the Balmer lines enabled measurement of dust reddening coefficients. Variations in the line ratios between the different lensed images are also observed, indicating that the spectra are probing different regions of the lensed galaxies. In all respects, the lensed objects appear fairly typical of ultraviolet-selected star-forming galaxies at z ~ 2. The Clone occupies a position on the emission-line diagnostic diagram of [O III]/Hβ versus [N II]/Hα that is offset from the locations of z ~ 0 galaxies. Our new NIRSPEC measurements may provide quantitative insights into why high-redshift objects display such properties. From the [S II] line ratio, high electron densities (~1000 cm-3) are inferred compared

  3. The peculiar optical-UV X-ray spectra of the X-ray weak quasar PG 0043+039

    NASA Astrophysics Data System (ADS)

    Kollatschny, W.; Schartel, N.; Zetzl, M.; Santos-Lleó, M.; Rodríguez-Pascual, P. M.; Ballo, L.; Talavera, A.

    2016-01-01

    Context. The object PG 0043+039 has been identified as a broad absorption line (BAL) quasar based on its UV spectra. However, this optical luminous quasar has not been detected before in deep X-ray observations, making it the most extreme X-ray weak quasar known today. Aims: This study aims to detect PG 0043+039 in a deep X-ray exposure. The question is what causes the extreme X-ray weakness of PG 0043+039? Does PG 0043+039 show other spectral or continuum peculiarities? Methods: We took simultaneous deep X-ray spectra with XMM-Newton, far-ultraviolet (FUV) spectra with the Hubble Space Telescope (HST), and optical spectra of PG 0043+039 with the Hobby-Eberly Telescope (HET) and Southern African Large Telescope (SALT) in July, 2013. Results: We have detected PG 0043+039 in our X-ray exposure taken in 2013. We presented our first results in a separate paper (Kollatschny et al. 2015). PG 0043+039 shows an extreme αox gradient (αox = -2.37). Furthermore, we were able to verify an X-ray flux of this source in a reanalysis of the X-ray data taken in 2005. At that time, it was fainter by a factor of 3.8 ±0.9 with αox = -2.55. The X-ray spectrum is compatible with a normal quasar power-law spectrum (Γ = 1.70-0.45+0.57) with moderate intrinsic absorption (NH = 5.5-3.9+6.9 × 1021 cm-2) and reflection. The UV/optical flux of PG 0043+039 has increased by a factor of 1.8 compared to spectra taken in the years 1990-1991. The FUV spectrum is highly peculiar and dominated by broad bumps besides Lyα. There is no detectable Lyman edge associated with the BAL absorbing gas seen in the CIV line. PG 0043+039 shows a maximum in the overall continuum flux at around λ ≈ 2500 Å in contrast to most other AGN where the maximum is found at shorter wavelengths. All the above is compatible with an intrinsically X-ray weak quasar, rather than an absorbed X-ray emission. Besides strong FeII multiplets and broad Balmer and HeI lines in the optical band we only detect a narrow [O ii

  4. Raman spectra of carotenoids in natural products.

    PubMed

    Withnall, Robert; Chowdhry, Babur Z; Silver, Jack; Edwards, Howell G M; de Oliveira, Luiz F C

    2003-08-01

    Resonance Raman spectra of naturally occurring carotenoids have been obtained from nautilus, periwinkle (Littorina littorea) and clam shells under 514.5 nm excitation and these spectra are compared with the resonance Raman spectra obtained in situ from tomatoes, carrots, red peppers and saffron. The tomatoes, carrots and red peppers gave rise to resonance Raman spectra exhibiting a nu1 band at ca. 1520 cm(-1), in keeping with its assignment to carotenoids with ca. nine conjugated carbon-carbon double bonds in their main chains, whereas the resonance Raman spectrum of saffron showed a nu1 band at 1537 cm(-1) which can be assigned to crocetin, having seven conjugated carbon-carbon double bonds. A correlation between nu1 wavenumber location and effective conjugated chain length has been used to interpret the data obtained from the shells, and the wavenumber position (1522 cm(-1)) of the nu1 band of the carotenoid in the orange clam shell suggests that it contains nine conjugated double bonds in the main chain. However, the black periwinkle and nautilus shells exhibit nu1 bands at 1504 and 1496 cm(-1), respectively. On the basis of the correlation between nu1 wavenumber location and effective conjugated chain length, this indicates that they contain carotenoids with longer conjugated chains, the former having ca. 11 double bonds and the latter ca. 13 or even more. Raman spectra of the nautilus, periwinkle and clam shells also exhibited a strong band at 1085 cm(-1) and a doublet with components at 701 and 705 cm(-1), which can be assigned to biogenic calcium carbonate in the aragonite crystallographic form. PMID:12909134

  5. Improved predictions of reactor antineutrino spectra

    NASA Astrophysics Data System (ADS)

    Mueller, Th. A.; Lhuillier, D.; Fallot, M.; Letourneau, A.; Cormon, S.; Fechner, M.; Giot, L.; Lasserre, T.; Martino, J.; Mention, G.; Porta, A.; Yermia, F.

    2011-05-01

    Precise predictions of the antineutrino spectra emitted by nuclear reactors is a key ingredient in measurements of reactor neutrino oscillations as well as in recent applications to the surveillance of power plants in the context of nonproliferation of nuclear weapons. We report new calculations including the latest information from nuclear databases and a detailed error budget. The first part of this work is the so-called ab initio approach where the total antineutrino spectrum is built from the sum of all β branches of all fission products predicted by an evolution code. Systematic effects and missing information in nuclear databases lead to final relative uncertainties in the 10-20% range. A prediction of the antineutrino spectrum associated with the fission of U238 is given based on this ab initio method. For the dominant isotopes we developed a more accurate approach combining information from nuclear databases and reference electron spectra associated with the fission of U235, Pu239, and Pu241, measured at Institut Laue-Langevin (ILL) in the 1980s. We show how the anchor point of the measured total β spectra can be used to suppress the uncertainty in nuclear databases while taking advantage of all the information they contain. We provide new reference antineutrino spectra for U235, Pu239, and Pu241 isotopes in the 2-8 MeV range. While the shapes of the spectra and their uncertainties are comparable to those of the previous analysis of the ILL data, the normalization is shifted by about +3% on average. In the perspective of the reanalysis of past experiments and direct use of these results by upcoming oscillation experiments, we discuss the various sources of errors and their correlations as well as the corrections induced by off-equilibrium effects.

  6. Raman spectra of carotenoids in natural products

    NASA Astrophysics Data System (ADS)

    Withnall, Robert; Chowdhry, Babur Z.; Silver, Jack; Edwards, Howell G. M.; de Oliveira, Luiz F. C.

    2003-08-01

    Resonance Raman spectra of naturally occurring carotenoids have been obtained from nautilus, periwinkle ( Littorina littorea) and clam shells under 514.5 nm excitation and these spectra are compared with the resonance Raman spectra obtained in situ from tomatoes, carrots, red peppers and saffron. The tomatoes, carrots and red peppers gave rise to resonance Raman spectra exhibiting a ν1 band at ca. 1520 cm -1, in keeping with its assignment to carotenoids with ca. nine conjugated carboncarbon double bonds in their main chains, whereas the resonance Raman spectrum of saffron showed a ν1 band at 1537 cm -1 which can be assigned to crocetin, having seven conjugated carboncarbon double bonds. A correlation between ν1 wavenumber location and effective conjugated chain length has been used to interpret the data obtained from the shells, and the wavenumber position (1522 cm -1) of the ν1 band of the carotenoid in the orange clam shell suggests that it contains nine conjugated double bonds in the main chain. However, the black periwinkle and nautilus shells exhibit ν1 bands at 1504 and 1496 cm -1, respectively. On the basis of the correlation between ν1 wavenumber location and effective conjugated chain length, this indicates that they contain carotenoids with longer conjugated chains, the former having ca. 11 double bonds and the latter ca. 13 or even more. Raman spectra of the nautilus, periwinkle and clam shells also exhibited a strong band at 1085 cm -1 and a doublet with components at 701 and 705 cm -1, which can be assigned to biogenic calcium carbonate in the aragonite crystallographic form.

  7. Improved predictions of reactor antineutrino spectra

    SciTech Connect

    Mueller, Th. A.; Lhuillier, D.; Letourneau, A.

    2011-05-15

    Precise predictions of the antineutrino spectra emitted by nuclear reactors is a key ingredient in measurements of reactor neutrino oscillations as well as in recent applications to the surveillance of power plants in the context of nonproliferation of nuclear weapons. We report new calculations including the latest information from nuclear databases and a detailed error budget. The first part of this work is the so-called ab initio approach where the total antineutrino spectrum is built from the sum of all {beta} branches of all fission products predicted by an evolution code. Systematic effects and missing information in nuclear databases lead to final relative uncertainties in the 10-20% range. A prediction of the antineutrino spectrum associated with the fission of {sup 238}U is given based on this ab initio method. For the dominant isotopes we developed a more accurate approach combining information from nuclear databases and reference electron spectra associated with the fission of {sup 235}U, {sup 239}Pu, and {sup 241}Pu, measured at Institut Laue-Langevin (ILL) in the 1980s. We show how the anchor point of the measured total {beta} spectra can be used to suppress the uncertainty in nuclear databases while taking advantage of all the information they contain. We provide new reference antineutrino spectra for {sup 235}U, {sup 239}Pu, and {sup 241}Pu isotopes in the 2-8 MeV range. While the shapes of the spectra and their uncertainties are comparable to those of the previous analysis of the ILL data, the normalization is shifted by about +3% on average. In the perspective of the reanalysis of past experiments and direct use of these results by upcoming oscillation experiments, we discuss the various sources of errors and their correlations as well as the corrections induced by off-equilibrium effects.

  8. Discrimination of phytoplankton classes using characteristic spectra of 3D fluorescence spectra

    NASA Astrophysics Data System (ADS)

    Zhang, Qian-Qian; Lei, Shu-He; Wang, Xiu-Lin; Wang, Lei; Zhu, Chen-Jian

    2006-02-01

    The discrimination of phytoplankton classes using the characteristic fluorescence spectra extracted from three-dimensional fluorescence spectra was investigated. Single species cultures of 11 phytoplankton species, representing 5 major phytoplankton divisions, were used. The 3D fluorescence spectra of the cultures grown at different temperatures (20 and 15 °C) and illumination intensities (140, 80 and 30 μM m -2 s -1) were measured and their feature extraction methods were explored. Ordering Rayleigh and Raman scattering data as zero, the obtained excitation-emission matrices were processed by both singular value decomposition (SVD) and trilinear decomposition methods. The resulting first principal component can be regarded as the characteristic spectrum of the original 3D fluorescence spectrum. The analysis shows that such characteristic spectra have a discriminatory capability. At different temperatures, the characteristic spectra of Isochrysis galbana, Platymonas helgolanidica and Skeletonema costatuma have high degrees of similarity to their own species samples, while the spectra similarities of Alexandrium tamarense, Prorocentrum dentatum, Pseudo-nitzschia pungens, Chaetoceros curvisetus, Ch. Debilis, Ch. Didymus and Synechococcus sp. are not as significant as the other three species. C. curvisetus, Ch. Debilis and Ch. Didymus, belonging to genus Chaetoceros, have identical spectra and cannot be discriminated at all. Regarding all six diatom species as one class, the average discriminant error rate is below 9%. It is worth mentioning that the diatom class can be distinguished from A. tamarense and P. dentatum, which belong to Dinophyta.

  9. Raman spectra of deuteriated taurine single crystals

    NASA Astrophysics Data System (ADS)

    Souza, J. M. de; Lima, R. J. C.; Freire, P. T. C.; Sasaki, J. M.; Melo, F. E. A.; Filho, J. Mendes; Jones, Derry W.

    2005-05-01

    The polarized Raman spectra of partially deuteriated taurine [(ND 3+) 0.65(NH 3+) 0.35(CH 2) 2SO 3-] crystals from x( zz) x and x( zy) x scattering geometries of the A g and B g irreducible representations of the factor group C 2h are reported. The temperature-dependent Raman spectra of partially deuteriated taurine do not reveal any evidence of the structural phase transition undergone by normal taurine at about 250 K, but an anomaly observed in the 180 cm -1 band at ˜120 K implies a different dynamic for this band (which is involved in a pressure-induced phase transition) in the deuteriated crystal.

  10. Measurement and interpretation of plutonium spectra

    SciTech Connect

    Blaise, J.; Fred, M.S.; Carnall, W.T.; Crosswhite, H.M.; Crosswhite, H.

    1982-01-01

    The atomic spectroscopic data available for plutonium are among the rickest of any in the periodic system. They include high-resolution grating and Fourier-transform spectra as well as extensive Zeeman and isotope-shift studies. We summarize the present status of the term analysis and cite the configurations that have been identified. A least-squares adjustment of a parametric Hamiltonian for configurations of both Pu I and Pu II has shown that almost all of the expected low levels are now known. The use of a model Hamiltonian applicable to both lanthanide and actinide atomic species has been applied to the low configurations of Pu I and Pu II making use of trends predicted by ab initio calculations. This same model has been used to describe the energy levels of Pu/sup 3 +/ in LaCl/sub 3/, and an extension has permitted preliminary calculations of the spectra of other valence states.

  11. Creating semiconductor metafilms with designer absorption spectra

    PubMed Central

    Kim, Soo Jin; Fan, Pengyu; Kang, Ju-Hyung; Brongersma, Mark L.

    2015-01-01

    The optical properties of semiconductors are typically considered intrinsic and fixed. Here we leverage the rapid developments in the field of optical metamaterials to create ultrathin semiconductor metafilms with designer absorption spectra. We show how such metafilms can be constructed by placing one or more types of high-index semiconductor antennas into a dense array with subwavelength spacings. It is argued that the large absorption cross-section of semiconductor antennas and their weak near-field coupling open a unique opportunity to create strongly absorbing metafilms whose spectral absorption properties directly reflect those of the individual antennas. Using experiments and simulations, we demonstrate that near-unity absorption at one or more target wavelengths of interest can be achieved in a sub-50-nm-thick metafilm using judiciously sized and spaced Ge nanobeams. The ability to create semiconductor metafilms with custom absorption spectra opens up new design strategies for planar optoelectronic devices and solar cells. PMID:26184335

  12. Specific heat spectra for quasiperiodic ladder sequences

    NASA Astrophysics Data System (ADS)

    Moreira, D. A.; Albuquerque, E. L.; Bezerra, C. G.

    2006-12-01

    We performed a theoretical study of the specific heat C(T) as a function of the temperature for double-strand quasiperiodic sequences. To mimic DNA molecules, the sequences are made up from the nucleotides guanine G, adenine A, cytosine C and thymine T, arranged according to the Fibonacci and Rudin-Shapiro quasiperiodic sequences. The energy spectra are calculated using the two-dimensional Schrödinger equation, in a tight-binding approximation, with the on-site energy exhibiting long-range disorder and non-random hopping amplitudes. We compare the specific heat features of these quasiperiodic artificial sequences to the spectra considering a segment of the first sequenced human chromosome 22 (Ch22), a real genomic DNA sequence.

  13. Energy spectra in elasto-inertial turbulence

    NASA Astrophysics Data System (ADS)

    Valente, P. C.; da Silva, C. B.; Pinho, F. T.

    2016-07-01

    Direct numerical simulations of statistically steady homogeneous isotropic turbulence in viscoelastic fluids described by the FENE-P model are presented. Emphasis is given to large polymer relaxation times compared to the eddy turnover time, which is a regime recently termed elasto-inertial turbulence. In this regime the polymers are ineffective in dissipating kinetic energy but they play a lead role in transferring kinetic energy to the small solvent scales which turns out to be concomitant with the depletion of the usual non-linear energy cascade. However, we show that the non-linear interactions are still highly active, but they lead to no net downscale energy transfer because the forward and reversed energy cascades are nearly balanced. Finally, we show that the tendency for a steeper elasto-inertial power-law spectra is reversed for large polymer relaxation times and the spectra tend towards the usual k-5/3 functional form.

  14. Origin of electron spectra and its characteristics

    NASA Astrophysics Data System (ADS)

    Mineev, Yu. V.

    This work presents the data on differential energy spectra of cosmic electrons with energies 0.1-6.0 MeV from the Pioneer-8-11, Prognoz-4-10, IMP-6,7,8, and Intercosmos-19 (polar cap measurements) spacecraft during 1975-1998. Some different sources of energetic electron are discussed. Analysis of the spectra permits a conclusion about a preferential contribution of galactic, solar and Jupiterian sources, depending on energies and on time of measurements. The dependencies of the sign and values of north-south asymmetry on the sector structure of the interplanetary magnetic field are obtained. The asymmetry sign and the size of cosmic electron fluxes for the above energies are compared with the earlier data in the high and low electron energy ranges for solar cycles 21-22.

  15. Neutron Spectra in a 15 MV LINAC

    SciTech Connect

    Vega-Carrillo, H. R.; Chu, Wei-Han; Tung, Chuan-Jong; Lan, Jen-Hong

    2010-12-07

    Neutron spectra were calculated inside the treatment hall of a 15 MV LINAC, calculations were carried out using Monte Carlo methods. With a Bonner sphere spectrometer with pairs of thermoluminiscent dosimeters the neutron spectrum at 100 cm from the isocenter was measured and compared with the calculated spectrum. All the spectra in the treatment hall show the presence of evaporation and knock-on neutrons; also the room-return due to the hall features is shown. In the maze the large contribution are due to epithermal and thermal neutrons. A good agreement between the calculated and measured spectrum at 100 cm was noticed, from this comparison the differences are attributed to the water content in the concrete of the hall.

  16. 8- to 13-micron spectra of asteroids

    NASA Astrophysics Data System (ADS)

    Green, S. F.; Eaton, N.; Aitken, D. K.; Roche, P. F.; Meadows, A. J.

    1985-05-01

    It is pointed out that thermal emission from asteroids reaches a maximum in the 10- to 20-micron region. In connection with the present investigation, a uniform set of spectra was obtained in the 8- to 13-micron region for 12 asteroids (together with additional observations of 19 Fortuna). These spectra provide a potentially valuable data set for future use (e.g., with IRAS data). The main conclusion from the obtained results is that diagnostic emission features of the type observed by Feierberg et al. (1983) are not common in C- and M-type asteroids. Optical studies of 19 Fortuna do not reveal any unusual properties which distinguish it from other C-type asteroids observed.

  17. Creating semiconductor metafilms with designer absorption spectra

    NASA Astrophysics Data System (ADS)

    Kim, Soo Jin; Fan, Pengyu; Kang, Ju-Hyung; Brongersma, Mark L.

    2015-07-01

    The optical properties of semiconductors are typically considered intrinsic and fixed. Here we leverage the rapid developments in the field of optical metamaterials to create ultrathin semiconductor metafilms with designer absorption spectra. We show how such metafilms can be constructed by placing one or more types of high-index semiconductor antennas into a dense array with subwavelength spacings. It is argued that the large absorption cross-section of semiconductor antennas and their weak near-field coupling open a unique opportunity to create strongly absorbing metafilms whose spectral absorption properties directly reflect those of the individual antennas. Using experiments and simulations, we demonstrate that near-unity absorption at one or more target wavelengths of interest can be achieved in a sub-50-nm-thick metafilm using judiciously sized and spaced Ge nanobeams. The ability to create semiconductor metafilms with custom absorption spectra opens up new design strategies for planar optoelectronic devices and solar cells.

  18. Creating semiconductor metafilms with designer absorption spectra.

    PubMed

    Kim, Soo Jin; Fan, Pengyu; Kang, Ju-Hyung; Brongersma, Mark L

    2015-01-01

    The optical properties of semiconductors are typically considered intrinsic and fixed. Here we leverage the rapid developments in the field of optical metamaterials to create ultrathin semiconductor metafilms with designer absorption spectra. We show how such metafilms can be constructed by placing one or more types of high-index semiconductor antennas into a dense array with subwavelength spacings. It is argued that the large absorption cross-section of semiconductor antennas and their weak near-field coupling open a unique opportunity to create strongly absorbing metafilms whose spectral absorption properties directly reflect those of the individual antennas. Using experiments and simulations, we demonstrate that near-unity absorption at one or more target wavelengths of interest can be achieved in a sub-50-nm-thick metafilm using judiciously sized and spaced Ge nanobeams. The ability to create semiconductor metafilms with custom absorption spectra opens up new design strategies for planar optoelectronic devices and solar cells. PMID:26184335

  19. Sulphur compounds in cometary IUE spectra

    NASA Technical Reports Server (NTRS)

    Krishna Swamy, K. S.; Wallis, M. K.

    1987-01-01

    From a study of cometary IUE spectra, a tentative identification of bands of the B-X systems of the SO molecule in the comet IRAS-Araki-Alcock in the 2200-2400 A region is reported, and it is suggested that sulphur compounds are more prevalent in comets than has been previously realized. S(+) and possibly SH are evident in comet Halley spectra, and new bands in the (A-X) system of CS and the (B-X) system of S2 are identified. The present results throw doubts on previous assessments of dust abundances from scattered continua in the 2900-3000 A region. The relatively strong abundance of S2 compared to OH in the Cernis and Bowell comets suggests that S2 is not well mixed and is not bound in H2O-ice.

  20. Characteristics of magnetospheric radio noise spectra

    NASA Technical Reports Server (NTRS)

    Herman, J. R.

    1976-01-01

    Magnetospheric radio noise spectra (30 kHz to 10 MHz) taken by IMP-6 and RAE-2 exhibit time-varying characteristics which are related to spacecraft position and magnetospheric processes. In the mid-frequency range (100-1,000 kHz) intense noise peaks rise by a factor of 100 or more above background; 80% of the peak frequencies are within the band 125 kHz to 600 kHz, and the peak occurs most often (18% of the time) at 280 kHz. This intense mid-frequency noise has been detected at radial distances from 1.3 Re to 60 Re on all sides of the Earth during magnetically quiet as well as disturbed periods. Maximum occurrence of the mid-frequency noise is in the evening to midnight hours where splash-type energetic particle precipitation takes place. ""Magnetospheric lightning'' can be invoked to explain the spectral shape of the observed spectra.

  1. Analysis of spectra using correlation functions

    NASA Technical Reports Server (NTRS)

    Beer, Reinhard; Norton, Robert H.

    1988-01-01

    A novel method is presented for the quantitative analysis of spectra based on the properties of the cross correlation between a real spectrum and either a numerical synthesis or laboratory simulation. A new goodness-of-fit criterion called the heteromorphic coefficient H is proposed that has the property of being zero when a fit is achieved and varying smoothly through zero as the iteration proceeds, providing a powerful tool for automatic or near-automatic analysis. It is also shown that H can be rendered substantially noise-immune, permitting the analysis of very weak spectra well below the apparent noise level and, as a byproduct, providing Doppler shift and radial velocity information with excellent precision. The technique is in regular use in the Atmospheric Trace Molecule Spectroscopy (ATMOS) project and operates in an interactive, realtime computing environment with turn-around times of a few seconds or less.

  2. Bone densitometry using x-ray spectra

    NASA Astrophysics Data System (ADS)

    Krmar, M.; Shukla, S.; Ganezer, K.

    2010-10-01

    In contrast to the two distinct energy regions that are involved in dual-energy x-ray absorptiometry for bone densitometry, the complete spectrum of a beam transmitted through two layers of different materials is utilized in this study to calculate the areal density of each material. Test objects constructed from aluminum and Plexiglas were used to simulate cortical bone and soft tissue, respectively. Solid-state HPGe (high-purity germanium) detectors provided high-resolution x-ray spectra over an energy range of approximately 20-80 keV. Areal densities were obtained from spectra using two methods: a system of equations for two spectral regions and a nonlinear fit of the entire spectrum. Good agreement with the known areal densities of aluminum was obtained over a wide range of PMMA thicknesses. The spectral method presented here can be used to decrease beam hardening at a small number of bodily points selected for examination.

  3. Primordial power spectra from anisotropic inflation

    SciTech Connect

    Dulaney, Timothy R.; Gresham, Moira I.

    2010-05-15

    We examine cosmological perturbations in a dynamical theory of inflation in which an Abelian gauge field couples directly to the inflaton, breaking conformal invariance. When the coupling between the gauge field and the inflaton takes a specific form, inflation becomes anisotropic and anisotropy can persist throughout inflation, avoiding Wald's no-hair theorem. After discussing scenarios in which anisotropy can persist during inflation, we calculate the dominant effects of a small persistent anisotropy on the primordial gravitational wave and curvature perturbation power spectra using the ''in-in'' formalism of perturbation theory. We find that the primordial power spectra of cosmological perturbations gain significant direction dependence and that the fractional direction dependence of the tensor power spectrum is suppressed in comparison to that of the scalar power spectrum.

  4. Raman spectra of shocked minerals. I - Olivine

    NASA Technical Reports Server (NTRS)

    Heymann, D.; Celucci, T. A.

    1988-01-01

    The Raman spectra of olivine contained in a chip of the Twin Sisters Peak (Washington) dunite shocked to 22.2 GPa is shown to be identical to that of unshocked olivine in the same rock. The Raman spectra of powder of the rock shocked to 20.1 GPa and of chips shocked to 59.5 GPa and 60.7 GPa display strong and broad low-frequency features with crests at 475/cm, 556/cm, and 572/cm, and broad high-frequency features near 1100/cm. It is suggested that these features are due to the formation of olivine glass with a considerable degree of three-dimensional Si-O-Si linkage having scattered domains of greatly variable grain size, internal structure, and chemical composition.

  5. Automated analysis of slitless spectra - Stars

    NASA Astrophysics Data System (ADS)

    Beauchemin, M.; Borra, E. F.; Levesque, S.

    1991-09-01

    The stellar spectral classification that can be achieved with very low-dispersion spectroscopy is examined. Several methods are applied to slitless spectra taken from the automated grens plates analysis project undertaken at Laval University. It is suggested that an accuracy in B - V of about 0.1 mag at B approximating 19 for stars bluer than B - V below 0.8 mag or better for redder stars can be obtained by probing the continuum. Results from DDO-like photometry show that grens data behave similarly to the Gunn and Stryker library of standard stars for many indices. Results of multivariate analysis are coherent with the stellar spectral classification and provide a powerful and objective means of cataloging spectra of the same spectral shape.

  6. Inflation and alternatives with blue tensor spectra

    SciTech Connect

    Wang, Yi; Xue, Wei E-mail: wei.xue@sissa.it

    2014-10-01

    We study the tilt of the primordial gravitational waves spectrum. A hint of blue tilt is shown from analyzing the BICEP2 and POLARBEAR data. Motivated by this, we explore the possibilities of blue tensor spectra from the very early universe cosmology models, including null energy condition violating inflation, inflation with general initial conditions, and string gas cosmology, etc. For the simplest G-inflation, blue tensor spectrum also implies blue scalar spectrum. In general, the inflation models with blue tensor spectra indicate large non-Gaussianities. On the other hand, string gas cosmology predicts blue tensor spectrum with highly Gaussian fluctuations. If further experiments do confirm the blue tensor spectrum, non-Gaussianity becomes a distinguishing test between inflation and alternatives.

  7. Knowledge Discovery in Mega-Spectra Archives

    NASA Astrophysics Data System (ADS)

    Škoda, P.; Bromová, P.; Lopatovsk'y, L.; Palička, A.; Vávzný, J.

    2015-09-01

    The recent progress of astronomical instrumentation resulted in the construction of multi-object spectrographs with hundreds to thousands of micro-slits or optical fibres allowing the acquisition of tens of thousands of spectra of celestial objects per observing night. Currently there are two spectroscopic surveys containing millions of spectra. These surveys are being processed by automatic pipelines, spectrum by spectrum, in order to estimate physical parameters of individual objects resulting in extensive catalogues, used typically to construct the better models of space-kinematic structure and evolution of the Universe or its subsystems. Such surveys are, however, very good source of homogenised, pre-processed data for application of machine learning techniques common in Astroinformatics. We present challenges of knowledge discovery in such surveys as well as practical examples of machine learning based on specific shapes of spectral features used in searching for new candidates of interesting astronomical objects, namely Be and B[e] stars and quasars.

  8. Ab initio infrared and Raman spectra

    NASA Technical Reports Server (NTRS)

    Fredkin, D. R.; White, S. R.; Wilson, K. R.; Komornicki, A.

    1983-01-01

    It is pointed out that with increased computer power and improved computational techniques, such as the gradients developed in recent years, it is becoming practical to compute spectra ab initio, from the fundamental constants of nature, for systems of increasing complexity. The present investigation has the objective to explore several possible ab initio approaches to spectra, giving particular attention to infrared and nonresonance Raman. Two approaches are discussed. The sequential approach, in which first the electronic part and then later the nuclear part of the Born-Oppenheimer approximation is solved, is appropriate for small systems. The simultaneous approach, in which the electronic and nuclear parts are solved at the same time, is more appropriate for many-atom systems. A review of the newer quantum gradient techniques is provided, and the infrared and Raman spectral band contours for the water molecule are computed.

  9. Optical spectra of FLASH generated plasmas

    NASA Astrophysics Data System (ADS)

    Stránský, M.; Rohlena, Karel

    2014-05-01

    Time integrated measurements of optical spectra of the plasma generated by pulses of the free electron laser facility FLASH on a solid target at DESY Hamburg are interpreted in terms of plasma hydrodynamics. It is shown that the main contribution to the optical range comes from the expanding stage of the plasma evolution on a ns scale, whereas the UV part is partially obscured by the optically dense outstreaming plasma near the ablated hole.

  10. The Zeeman effect in stellar spectra

    NASA Astrophysics Data System (ADS)

    Romanyuk, I. I.

    A short biography of Pieter Zeeman is presented. The main formulae for the normal, anomalous, quadratic Zeeman effects and Paschen-Back effect are given. Instrumentation for Zeeman effect measurements in stellar spectra is described, the most important scientific achievements in magnetic stars investigations with the world's largest telescopes for 50 years are demonstrated. The devices for magnetic measurements made at SAO and the main results of stellar magnetic observations obtained with the 6 m telescope are described in detail.

  11. 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] λλ7291, 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.

  12. Surface Electronic Spectra Detected by Atomic Desorption

    SciTech Connect

    Joly, Alan G.; Beck, Kenneth M.; Henyk, Matthias; Hess, Wayne P.; Sushko, Petr V.; Shluger, Alexander L.

    2003-10-10

    Using continuously tunable laser excitation of KI we measure the velocity profiles and the yield of desorbing hyperthermal iodine atoms as a function of photon energy. Based on the theoretical model of desorption we demonstrate that these spectra display a signature of a surface exciton and constitute a new sensitive method of surface specific desorption spectroscopy. Our results demonstrate that creation of surface excitions can be a much more general phenomenon than was previously thought based on extant spectroscopic measurements.

  13. Understanding the baryon and meson spectra

    SciTech Connect

    Pennington, Michael R.

    2013-10-01

    A brief overview is given of what we know of the baryon and meson spectra, with a focus on what are the key internal degrees of freedom and how these relate to strong coupling QCD. The challenges, experimental, theoretical and phenomenological, for the future are outlined, with particular reference to a program at Jefferson Lab to extract hadronic states in which glue unambiguously contributes to their quantum numbers.

  14. Dynamical analysis of highly excited molecular spectra

    SciTech Connect

    Kellman, M.E.

    1993-12-01

    The goal of this program is new methods for analysis of spectra and dynamics of highly excited vibrational states of molecules. In these systems, strong mode coupling and anharmonicity give rise to complicated classical dynamics, and make the simple normal modes analysis unsatisfactory. New methods of spectral analysis, pattern recognition, and assignment are sought using techniques of nonlinear dynamics including bifurcation theory, phase space classification, and quantization of phase space structures. The emphasis is chaotic systems and systems with many degrees of freedom.

  15. HET Spectra of Three Recent Extragalactic Novae

    NASA Astrophysics Data System (ADS)

    Shafter, A. W.; Coelho, E. A.; Misselt, K. A.; Bode, M. F.; Darnley, M. J.; Quimby, R.

    2006-10-01

    We report optical spectroscopic observations (4280Å - 7280Å) obtained with the HET of three extragalactic novae: Nova M31 2006 No. 9 (ATEL #887), Nova M32 2006 No. 1 (CBET #591), and Nova M33 2006 No. 1 (CBET #655). The spectra were obtained on 24 Sep 2006 UT, 30 Sep 2006 UT, and 02 Oct 2006 UT, corresponding to approximately 6, 65, and 4 days post discovery, for the three novae respectively.

  16. Reanalysis of Tyrannosaurus rex Mass Spectra.

    PubMed

    Bern, Marshall; Phinney, Brett S; Goldberg, David

    2009-09-01

    Asara et al. reported the detection of collagen peptides in a 68-million-year-old Tyrannosaurus rex bone by shotgun proteomics. This finding has been called into question as a possible statistical artifact. We reanalyze Asara et al.'s tandem mass spectra using a different search engine and different statistical tools. Our reanalysis shows a sample containing common laboratory contaminants, soil bacteria, and bird-like hemoglobin and collagen. PMID:19603827

  17. Quasar X-Ray Spectra Revisited: Erratum

    NASA Astrophysics Data System (ADS)

    Shastri, P.; Wilkes, B. J.; Elvis, M.; McDowell, J.

    1994-08-01

    In the paper "Quasar X-Ray Spectra Revisited " by P. Shastri, B. J. Wilkes, M. Elvis, and J. McDowell (ApJ, 410,29 [1993]), there is an error in the flux density levels in Figures 4a and 4b. As a result of an error during rebinning of the optical spectrophotometry data, the flux density levels in those two figures are a factor of 5 lower then their actual value.

  18. Dose spectra from energetic particles and neutrons

    NASA Astrophysics Data System (ADS)

    Schwadron, Nathan; Bancroft, Chris; Bloser, Peter; Legere, Jason; Ryan, James; Smith, Sonya; Spence, Harlan; Mazur, Joe; Zeitlin, Cary

    2013-10-01

    spectra from energetic particles and neutrons (DoSEN) are an early-stage space technology research project that combines two advanced complementary radiation detection concepts with fundamental advantages over traditional dosimetry. DoSEN measures not only the energy but also the charge distribution (including neutrons) of energetic particles that affect human (and robotic) health in a way not presently possible with current dosimeters. For heavy ions and protons, DoSEN provides a direct measurement of the lineal energy transfer (LET) spectra behind shielding material. For LET measurements, DoSEN contains stacks of thin-thick Si detectors similar in design to those used for the Cosmic Ray Telescope for the Effects of Radiation. With LET spectra, we can now directly break down the observed spectrum of radiation into its constituent heavy-ion components and through biologically based quality factors that provide not only doses and dose rates but also dose equivalents, associated rates, and even organ doses. DoSEN also measures neutrons from 10 to 100 MeV, which requires enough sensitive mass to fully absorb recoil particles that the neutrons produce. DoSEN develops the new concept of combining these independent measurements and using the coincidence of LET measurements and neutron detection to significantly reduce backgrounds in each measurement. The background suppression through the use of coincidence allows for significant reductions in size, mass, and power needed to provide measurements of dose, neutron dose, dose equivalents, LET spectra, and organ doses. Thus, we introduce the DoSEN concept: a promising low-mass instrument that detects the full spectrum of energetic particles, heavy ions, and neutrons to determine biological impact of radiation in space.

  19. Ultraviolet spectra of R Coronae Borealis stars

    NASA Technical Reports Server (NTRS)

    Holm, A. V.; Wu, C. C.

    1982-01-01

    An analysis of the International Ultraviolet Explorer spectra of the R CrB-type variables R CrB, RY Sgr, XX Cam, and MV Sgr suggests that: (1) it should be possible to construct useful models for the atmospheres of these hydrogen deficient, carbon rich stars if present standards of metallic line blanketing are used; and (2) the observed wavelength dependence of the circumstellar extinction is primarily due to circumstellar grains.

  20. Analysis of positron lifetime spectra in polymers

    NASA Technical Reports Server (NTRS)

    Singh, Jag J.; Mall, Gerald H.; Sprinkle, Danny R.

    1988-01-01

    A new procedure for analyzing multicomponent positron lifetime spectra in polymers was developed. It requires initial estimates of the lifetimes and the intensities of various components, which are readily obtainable by a standard spectrum stripping process. These initial estimates, after convolution with the timing system resolution function, are then used as the inputs for a nonlinear least squares analysis to compute the estimates that conform to a global error minimization criterion. The convolution integral uses the full experimental resolution function, in contrast to the previous studies where analytical approximations of it were utilized. These concepts were incorporated into a generalized Computer Program for Analyzing Positron Lifetime Spectra (PAPLS) in polymers. Its validity was tested using several artificially generated data sets. These data sets were also analyzed using the widely used POSITRONFIT program. In almost all cases, the PAPLS program gives closer fit to the input values. The new procedure was applied to the analysis of several lifetime spectra measured in metal ion containing Epon-828 samples. The results are described.

  1. Deconvolution of spectra for intimate mixtures

    NASA Technical Reports Server (NTRS)

    Mustard, John F.; Pieters, Carle M.; Pratt, Stephen F.

    1987-01-01

    Visible to near infrared reflectance spectra of macroscopic mixtures have been shown to be linear combinations of the reflections of the pure mineral components in the mixture. However, for microscopic mixtures the mixing systematics are in general nonlinear. The systematics may be linearized by conversion of reflectance to single scattering albedo (w), where the equations which relate reflectance to w depend on the method of data collection. Several proposed mixing models may be used to estimate mineral abundances from the reflectance spectra of intimate mixtures. These models are summarized and a revised model is presented. A noniterative (linear) least squares approach was used for curve fitting and the data, measured as bi-directional reflectance with incidence and emergence angles of 30 and 0 deg were converted to w by a simplified version of Hapke's equation for bi-directional reflectance. This model was tested with two mixture series composed of 45 to 75 micron particles: an anorthite-enstatite series and an olivine-magnetite series. The data indicate that the simplified Hapke's equation may be used to convolve reflectance spectra into mineral abundances if appropriate endmembers are known or derived from other techniques. For surfaces that contain a significant component of very low albedo material, a somewhat modified version of this technique will need to be developed. Since the abundances are calculated using a noniterative approach, the application of this method is especially efficient for large spectral data sets, such as those produced by mapping spectrometers.

  2. Infrared spectra of substituted polycylic aromatic hydrocarbons

    NASA Technical Reports Server (NTRS)

    Langhoff, S. R.; Bauschlicher, C. W. Jr; Hudgins, D. M.; Sandford, S. A.; Allamandola, L. J.

    1998-01-01

    Calculations are carried out using density functional theory (DFT) to determine the harmonic frequencies and intensities of 1-methylanthracene, 9-methylanthracene, 9-cyanoanthracene, 2-aminoanthracene, acridine, and their positive ions. The theoretical data are compared with matrix-isolation spectra for these species also reported in this work. The theoretical and experimental frequencies and relative intensities for the neutral species are in generally good agreement, whereas the positive ion spectra are only in qualitative agreement. Relative to anthracene, we find that substitution of a methyl or CN for a hydrogen does not significantly affect the spectrum other than to add the characteristic methyl C-H and C triple bond N stretches near 2900 and 2200 cm-1, respectively. However, addition of NH2 dramatically affects the spectrum of the neutral. Not only are the NH2 modes themselves strong, but this electron-withdrawing group induces sufficient partial charge on the ring to give the neutral molecule spectra characteristics of the anthracene cation. The sum of the absolute intensities is about four times larger for 2-aminoanthracene than those for 9-cyanoanthracene. Substituting nitrogen in the ring at the nine position (acridine) does not greatly alter the spectrum compared with anthracene.

  3. IRAS Low Resolution Spectra of Asteroids

    NASA Technical Reports Server (NTRS)

    Cohen, Martin; Walker, Russell G.

    2002-01-01

    Optical/near-infrared studies of asteroids are based on reflected sunlight and surface albedo variations create broad spectral features, suggestive of families of materials. There is a significant literature on these features, but there is very little work in the thermal infrared that directly probes the materials emitting on the surfaces of asteroids. We have searched for and extracted 534 thermal spectra of 245 asteroids from the original Dutch (Groningen) archive of spectra observed by the IRAS Low Resolution Spectrometer (LRS). We find that, in general, the observed shapes of the spectral continua are inconsistent with that predicted by the standard thermal model used by IRAS. Thermal models such as proposed by Harris (1998) and Harris et al.(1998) for the near-earth asteroids with the "beaming parameter" in the range of 1.0 to 1.2 best represent the observed spectral shapes. This implies that the IRAS Minor Planet Survey (IMPS, Tedesco, 1992) and the Supplementary IMPS (SIMPS, Tedesco, et al., 2002) derived asteroid diameters are systematically underestimated, and the albedos are overestimated. We have tentatively identified several spectral features that appear to be diagnostic of at least families of materials. The variation of spectral features with taxonomic class hints that thermal infrared spectra can be a valuable tool for taxonomic classification of asteroids.

  4. Meteor spectra in the EDMOND database

    NASA Astrophysics Data System (ADS)

    Koukal, J.; Gorková, S.; Srba, J.; Ferus, M.; Civiš, S.; di Pietro, C. A.

    2015-01-01

    We present a selection of five interesting meteor spectra obtained in the years 2014 and 2015 via CCTV video systems with a holographic grating, working in CEMENT and BRAMON meteor observation networks. Based on the EDMOND multi stations video meteor trajectory data an orbital classification of these meteors was performed. Selected meteors are members of the LYR, SPE, DSA and LVI meteor streams, one meteor is classified as sporadic background (SPO). In calibrated spectra the main chemical components were identified. Meteors are chemically classified based on relative intensities of the main spectral lines (or multiplets): Mg I (2), Na I (1), and Fe I (15). Bolide EN091214 is linked with the 23rd meteorite with known orbit (informally known as "Žďár"), two fragments of the parent body were found in the Czech Republic so far (August, 2015). For this particular event a time resolved spectral observation and comparison with laboratory spectra of LL3.2 chondritic meteorite are presented.

  5. Soil emissivity and reflectance spectra measurements.

    PubMed

    Sobrino, José A; Mattar, Cristian; Pardo, Pablo; Jiménez-Muñoz, Juan C; Hook, Simon J; Baldridge, Alice; Ibañez, Rafael

    2009-07-01

    We present an analysis of the laboratory reflectance and emissivity spectra of 11 soil samples collected on different field campaigns carried out over a diverse suite of test sites in Europe, North Africa, and South America from 2002 to 2008. Hemispherical reflectance spectra were measured from 2.0 to 14 microm with a Fourier transform infrared spectrometer, and x-ray diffraction analysis (XRD) was used to determine the mineralogical phases of the soil samples. Emissivity spectra were obtained from the hemispherical reflectance measurements using Kirchhoff's law and compared with in situ radiance measurements obtained with a CIMEL Electronique CE312-2 thermal radiometer and converted to emissivity using the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) temperature and emissivity separation algorithm. The CIMEL has five narrow bands at approximately the same positions as the ASTER. Results show a root mean square error typically below 0.015 between laboratory emissivity measurements and emissivity measurements derived from the field radiometer. PMID:19571921

  6. Low Temperature Reflectance Spectra of Titan Tholins

    NASA Technical Reports Server (NTRS)

    Roush, T. L.; Dalton, J. B.; Fonda, Mark (Technical Monitor)

    2001-01-01

    Compositional interpretation of remotely obtained reflectance spectra of outer solar system surfaces is achieved by a variety of methods. These include matching spectral curves, matching spectral features, quantitative spectral interpretation, and theoretical modeling of spectra. All of these approaches rely upon laboratory measurements of one kind or another. The bulk of these laboratory measurements are obtained with the sample of interest at ambient temperatures and pressures. However, surface temperatures of planets, satellites, and asteroids in the outer solar system are significantly cooler than ambient laboratory conditions on Earth. The infrared spectra of many materials change as a function of temperature. As has been recently demonstrated it is important to assess what effects colder temperatures have on spectral properties and hence, compositional interpretations. Titan tholin is a solid residue created by energetic processing of H-, C-, and N-bearing gases. Such residues can also be created by energetic processing if the gases are condensed into ices. Titan tholin has been suggested as a coloring agent for several surfaces in the outer solar system. Here we report laboratory measurements of Titan tholin at a temperature of 100 K and compare these to measurements of the same sample near room temperature. At low temperature the absorption features beyond 1 micrometer narrow slightly. At wavelengths greater than approx. 0.8 micrometer the overall reflectance of the sample decreases slightly making the sample less red at low temperatures. We will discuss the implications of the laboratory measurements for interpretation of cold outer solar system surfaces.

  7. VARIABILITY IN OPTICAL SPECTRA OF {epsilon} ORIONIS

    SciTech Connect

    Thompson, Gregory B.; Morrison, Nancy D. E-mail: nmorris@utnet.utoledo.edu

    2013-04-15

    We present the results of a time series analysis of 130 echelle spectra of {epsilon} Ori (B0 Ia), acquired over seven observing seasons between 1998 and 2006 at Ritter Observatory. The equivalent widths of H{alpha} (net) and He I {lambda}5876 were measured and radial velocities were obtained from the central absorption of He I {lambda}5876. Temporal variance spectra (TVS) revealed significant wind variability in both H{alpha} and He I {lambda}5876. The He I TVS have a double-peaked profile consistent with radial velocity oscillations. A periodicity search was carried out on the equivalent width and radial velocity data, as well as on wavelength-binned spectra. This analysis has revealed several periods in the variability with timescales of two to seven days. Many of these periods exhibit sinusoidal modulation in the associated phase diagrams. Several of these periods were present in both H{alpha} and He I, indicating a possible connection between the wind and the photosphere. Due to the harmonic nature of these periods, stellar pulsations may be the origin of some of the observed variability. Periods on the order of the rotational period were also detected in the He I line in the 1998-1999 season and in both lines during the 2004-2005 season. These periods may indicate rotational modulation due to structure in the wind.

  8. Soil emissivity and reflectance spectra measurements

    SciTech Connect

    Sobrino, Jose A.; Mattar, Cristian; Pardo, Pablo; Jimenez-Munoz, Juan C.; Hook, Simon J.; Baldridge, Alice; Ibanez, Rafael

    2009-07-01

    We present an analysis of the laboratory reflectance and emissivity spectra of 11 soil samples collected on different field campaigns carried out over a diverse suite of test sites in Europe, North Africa, and South America from 2002 to 2008. Hemispherical reflectance spectra were measured from 2.0 to 14 {mu}m with a Fourier transform infrared spectrometer, and x-ray diffraction analysis (XRD) was used to determine the mineralogical phases of the soil samples. Emissivity spectra were obtained from the hemispherical reflectance measurements using Kirchhoff's law and compared with in situ radiance measurements obtained with a CIMEL Electronique CE312-2 thermal radiometer and converted to emissivity using the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) temperature and emissivity separation algorithm. The CIMEL has five narrow bands at approximately the same positions as the ASTER. Results show a root mean square error typically below 0.015 between laboratory emissivity measurements and emissivity measurements derived from the field radiometer.

  9. Optical spectra analysis for breast cancer diagnostics

    NASA Astrophysics Data System (ADS)

    Belkov, S. A.; Kochemasov, G. G.; Lyubynskaya, T. E.; Maslov, N. V.; Nuzhny, A. S.; da Silva, L. B.; Rubenchik, A.

    2011-11-01

    Minimally invasive probe and optical biopsy system based on optical spectra recording and analysis seem to be a promising tool for early diagnostics of breast cancer. Light scattering and absorption spectra are generated continuously as far as the needle-like probe with one emitting and several collecting optical fibers penetrates through the tissues toward to the suspicious area. That allows analyzing not only the state of local site, but also the structure of tissues along the needle trace. The suggested method has the advantages of automated on-line diagnosing and minimal tissue destruction and in parallel with the conventional diagnostic procedures provides the ground for decision-making. 165 medical trials were completed in Nizhny Novgorod Regional Oncology Centre, Russia. Independent diagnoses were the results of fine biopsy and histology. Application of wavelet expansion and clasterization techniques for spectra analysis revealed several main spectral types for malignant and benign tumors. Automatic classification algorithm demonstrated specificity ˜90% and sensitivity ˜91%. Large amount of information, fuzziness in criteria and data noisiness make neural networks to be an attractive analytic tool. The model based on three-layer perceptron was tested over the sample of 29 `cancer' and 29 `non-cancer' cases and demonstrated total separation.

  10. Island shadows in wave directional spectra

    NASA Astrophysics Data System (ADS)

    Pawka, S. S.

    1983-03-01

    Shadows of individual islands are observed in directional spectra sampled with a high resolution linear array at Torrey Pines Beach, California. A detailed investigation of the spectra indicates that the Channel Islands restrict the wave energy density to certain narrow directional sectors. A deep spectral trough, associated with San Clemente Island, is a predominant feature in the well resolved spectra (wave frequencies ˜0.06-0.15 Hz). Negligible values of energy density in the center of this directional `gap' were consistently observed in the range 0.082-0.114 Hz. Measurable but low gap energy density values are seen in the high and low frequency regimes. Generation of high frequency waves (f≥0.13 Hz) by local winds generally smears the island windowing effects and even creates a spectral peak in a directional sector which is blocked from deep ocean exposure. Several estimation techniques are used in the directional spectrum analysis. These include the Maximum Likelihood Method (MLM) and two methods developed in this work. The two new techniques show significant improvement over the MLM in the definition of gaps in the spectrum. Although none of these methods is considered an `Optimal' estimator for general use, each displays some superior merit in particular directional spectrum estimation problems.

  11. Haloes Seen In UVIS Reflectance Spectra

    NASA Astrophysics Data System (ADS)

    Esposito, Larry W.; Bradley, E.; Colwell, J.; Sremcevic, M.

    2012-10-01

    UVIS SOI reflectance spectra show bright ‘haloes’ around the locations of some of the strongest resonances in Saturn’s A ring (Esposito etal 2005). UV spectra constrain the size and composition of the icy ring particles (Bradley etal 2010, 2012). We investigate the Janus 4:3, 5:3, 6:5 and Mimas 5:3 inner Lindblad resonances as well as at the Mimas 5:3 vertical resonance (bending wave location). Models of ring particle regolith evolution (Elliott and Esposito 2010) indicate the deeper regolith is made of older and purer ice. The strong resonances cause streamline crowding (Lewis and Stewart 2005) which damps the interparticle velocity, allowing temporary clumps to grow, which in turn increase the velocity, eroding the clumps and releasing smaller particles and regolith (see the predator-prey model of Esposito etal 2012). This cyclic behavior, driven by the resonant perturbation from the moon, can yield collision velocities greater than 1m/sec, sufficient to erode the aggregates (Blum 2006), exposing older, purer materials. Thus, the radial location of the strongest resonances can be where we find both large aggregates and disrupted fragments, in a balance maintained by the periodic moon forcing. If this stirring exposes older, and purer ice, the velocity threshold for eroding the aggregates can explain why only the strongest Lindblad resonances show haloes. UVIS spectra can determine the relative contributions of particle size and purity at these locations, for comparison to estimates from the regolith evolution models.

  12. Tunneling spectra of graphene on copper unraveled.

    PubMed

    Zhang, Xin; Stradi, Daniele; Liu, Lei; Luo, Hong; Brandbyge, Mads; Gu, Gong

    2016-06-22

    Scanning tunneling spectroscopy is often employed to study two-dimensional (2D) materials on conductive growth substrates, in order to gain information on the electronic structures of the 2D material-substrate systems, which can lead to insight into 2D material-substrate interactions, growth mechanisms, etc. The interpretation of the spectra can be complicated, however. Specifically for graphene grown on copper, there have been conflicting reports of tunneling spectra. A clear understanding of the mechanisms behind the variability is desired. In this work, we have revealed that the root cause of the variability in tunneling spectra is the variation in graphene-substrate coupling under various experimental conditions, providing a salutary perspective on the important role of 2D material-substrate interactions. The conclusions are drawn from measured data and theoretical calculations for monolayer, AB-stacked bilayer, and twisted bilayer graphene coexisting on the same substrates in areas with and without intercalated oxygen, demonstrating a high degree of consistency. The Van Hove singularities of the twisted graphene unambiguously indicate the Dirac energy between them, lending strong evidence to our assignment of the spectral features. In addition, we have discovered an O-Cu superstructure that has never been observed before. PMID:27297050

  13. Atomic Spectra Bibliography Databases at NIST

    NASA Astrophysics Data System (ADS)

    Kramida, A. E.

    2007-06-01

    In June 2006, our Atomic Spectroscopy Data Center released three new Bibliographic Databases (BD) containing references to papers with atomic data for controlled fusion research, modeling and diagnostics of astrophysical and terrestrial plasmas, and fundamental properties of electronic spectra of atoms and ions. The NIST Atomic Energy Levels and Spectra BD (http://physics.nist.gov/elevbib) [EL] is the first online version of the NIST bibliography on atomic energy levels and spectra, last published on paper in 1985. It includes more than 9300 references, mostly for years 1967 through 2004. Work is in progress to cover the latest years. The NIST Atomic Transition Probability BD, v. 8.1 (http://physics.nist.gov/fvalbib) [TP] with its 7200 references mainly covers years 1964 through 2006. The NIST Spectral Line Broadening BD, v. 2.0 (http://physics.nist.gov/linebrbib) [LB] has 3600 references, mostly for 1978 through 2006. It is a major upgrade of v. 1.0, which had only 800 references. All three databases are now maintained in a unified database management system that allows us to quickly update the contents. Updates become available to users on the next day. A new Data Entry module makes it easy to enter and categorize the data. This work is supported in part by the Office of Fusion Energy Sciences of the U.S. Department of Energy

  14. MAGNETIC ENERGY SPECTRA IN SOLAR ACTIVE REGIONS

    SciTech Connect

    Abramenko, Valentyna; Yurchyshyn, Vasyl

    2010-09-01

    Line-of-sight magnetograms for 217 active regions (ARs) with different flare rates observed at the solar disk center from 1997 January until 2006 December are utilized to study the turbulence regime and its relationship to flare productivity. Data from the SOHO/MDI instrument recorded in the high-resolution mode and data from the BBSO magnetograph were used. The turbulence regime was probed via magnetic energy spectra and magnetic dissipation spectra. We found steeper energy spectra for ARs with higher flare productivity. We also report that both the power index, {alpha}, of the energy spectrum, E(k) {approx} k{sup -}{alpha}, and the total spectral energy, W = {integral}E(k)dk, are comparably correlated with the flare index, A, of an AR. The correlations are found to be stronger than those found between the flare index and the total unsigned flux. The flare index for an AR can be estimated based on measurements of {alpha} and W as A = 10{sup b}({alpha}W){sup c}, with b = -7.92 {+-} 0.58 and c = 1.85 {+-} 0.13. We found that the regime of the fully developed turbulence occurs in decaying ARs and in emerging ARs (at the very early stage of emergence). Well-developed ARs display underdeveloped turbulence with strong magnetic dissipation at all scales.

  15. From plasmon spectra of metallic to vibron spectra of dielectric nanoparticles.

    PubMed

    Preston, Thomas C; Signorell, Ruth

    2012-09-18

    Light interacts surprisingly differently with small particles than with bulk or gas phase materials. This can cause rare phenomena such as the occurence of a "blue moon". Spectroscopic particle phenomena of similar physical origin have also spawned countless applications ranging from remote sensing to medicine. Despite the broad interest in particle spectra, their interpretation still poses many challenges. In this Account, we discuss the challenges associated with the analysis of infrared, or vibron, extinction spectra of small dielectric particles. The comparison with the more widely studied plasmon spectra of metallic nano-particles reveals many common features. The shape, size, and architecture of particles influence the band profiles in vibron and plasmon spectra in similar ways. However, the molecular structure of dielectric particles produces infrared spectral features that are more diverse and detailed or even unique to vibron spectra. More complexity means higher information content, but that also makes the spectra more difficult to interpret. Conventional models such as classical electromagnetic theory with a continuum description of the wavelength-dependent optical constants are often no longer applicable to these spectra. In cases where accurate optical constants are not available and for ultrafine particles, where the molecular structure and quantum effects become essential, researchers must resort to molecular models for light-particle interaction that do not require the prior knowledge of optical constants. In this Account, we illustrate how vibrational exciton approaches combined with molecular dynamics simulations and solid-state density functional calculations provide a viable solution to these challenges. Molecular models reveal two important characteristics of vibron spectra of small molecularly structured particles. The band profiles in vibron spectra are largely determined by transition dipole coupling between the molecules in a particle

  16. Near-infrared spectra of Jupiter, Saturn, and Uranus

    NASA Technical Reports Server (NTRS)

    Potter, A. E.

    1974-01-01

    Near infrared spectra of Jupiter, Saturn, and Uranus were measured at resolutions higher than previously available in the range from 6,000 to 10,750/cm. The resolution was 0.5/cm for Jupiter and Saturn, and 32/cm for Uranus. The spectra are presented both individually and as ratio spectra, in which the planetary spectra are divided by the solar spectrum. The Uranus spectrum is shown with Saturn, Jupiter, and Sun spectra reduced to the same resolution so that Uranus can be compared with the other outer planets. The high resolution Saturn, Jupiter, and Sun spectra are presented in parallel plots to simplify comparisons between them.

  17. Optimal construction of theoretical spectra for MS/MS spectra identification

    SciTech Connect

    Fridman, Tamah; Protopopescu, Vladimir A; Hurst, Gregory {Greg} B; Borziak, Andrei; Gorin, Andrey A

    2005-01-01

    We derive the optimal number of peaks (defined as the minimum number that provides the required efficiency of spectra identification) in the theoretical spectra as a function of: (i) the experimental accuracy, , of the measured ratio m/z; (ii) experimental spectrum density; (iii) size of the database; (iv) number of peaks in the theoretical spectra; and (v) types of ions that the peaks represent. We show that if theoretical spectra are constructed including b and y ions alone, then for =0.5, which is typical for high throughput data, peptide chains of 8 amino acids or longer can be identified based on the positions of peaks alone, at a rate of false identification below 1%. To discriminate between shorter peptides, additional (e.g., intensity-inferred) information is necessary. We derive the dependence of the probability of false identification on the number of peaks in the theoretical spectra and on the types of ions that the peaks represent. Our results suggest that the class of mass spectrum identification problems for which more elaborate development of fragmentation rules (such as intensity model, etc.) is required, can be reduced to the problems that involve homologous peptides.

  18. High precision radial velocities with GIANO spectra

    NASA Astrophysics Data System (ADS)

    Carleo, I.; Sanna, N.; Gratton, R.; Benatti, S.; Bonavita, M.; Oliva, E.; Origlia, L.; Desidera, S.; Claudi, R.; Sissa, E.

    2016-06-01

    Radial velocities (RV) measured from near-infrared (NIR) spectra are a potentially excellent tool to search for extrasolar planets around cool or active stars. High resolution infrared (IR) spectrographs now available are reaching the high precision of visible instruments, with a constant improvement over time. GIANO is an infrared echelle spectrograph at the Telescopio Nazionale Galileo (TNG) and it is a powerful tool to provide high resolution spectra for accurate RV measurements of exoplanets and for chemical and dynamical studies of stellar or extragalactic objects. No other high spectral resolution IR instrument has GIANO's capability to cover the entire NIR wavelength range (0.95-2.45 μm) in a single exposure. In this paper we describe the ensemble of procedures that we have developed to measure high precision RVs on GIANO spectra acquired during the Science Verification (SV) run, using the telluric lines as wavelength reference. We used the Cross Correlation Function (CCF) method to determine the velocity for both the star and the telluric lines. For this purpose, we constructed two suitable digital masks that include about 2000 stellar lines, and a similar number of telluric lines. The method is applied to various targets with different spectral type, from K2V to M8 stars. We reached different precisions mainly depending on the H-magnitudes: for H ˜ 5 we obtain an rms scatter of ˜ 10 m s-1, while for H ˜ 9 the standard deviation increases to ˜ 50 ÷ 80 m s-1. The corresponding theoretical error expectations are ˜ 4 m s-1 and 30 m s-1, respectively. Finally we provide the RVs measured with our procedure for the targets observed during GIANO Science Verification.

  19. Atomic and Molecular Aspects of Astronomical Spectra

    NASA Astrophysics Data System (ADS)

    Sochi, Taha

    2012-11-01

    In the first section we present the atomic part where a C2+ atomic target was prepared and used to generate theoretical data to investigate recombination lines arising from electron-ion collisions in thin plasma. R-matrix method was used to describe the C2+ plus electron system. Theoretical data concerning bound and autoionizing states were generated in the intermediate-coupling approximation. The data were used to generate dielectronic recombination data for C+ which include transition lines, oscillator strengths, radiative transition probabilities, emissivities and dielectronic recombination coefficients. The data were cast in a line list containing 6187 optically-allowed transitions which include many C II lines observed in astronomical spectra. This line list was used to analyze the spectra from a number of astronomical objects, mainly planetary nebulae, and identify their electron temperature. The electron temperature investigation was also extended to include free electron energy analysis to investigate the long-standing problem of discrepancy between the results of recombination and forbidden lines analysis and its possible connection to the electron distribution. In the second section we present the results of our molecular investigation; the generation of a comprehensive, calculated line list of frequencies and transition probabilities for H2D+. The line list contains over 22 million rotational-vibrational transitions occurring between more than 33 thousand energy levels and covers frequencies up to 18500 cm-1. About 15% of these levels are fully assigned with approximate rotational and vibrational quantum numbers. A temperature-dependent partition function and cooling function are presented. Temperature-dependent synthetic spectra for the temperatures T=100, 500, 1000 and 2000 K in the frequency range 0-10000 cm-1 were also generated and presented graphically.

  20. Effect of Temperature on Jet Velocity Spectra

    NASA Technical Reports Server (NTRS)

    Bridges, James E.; Wernet, Mark P.

    2007-01-01

    Statistical jet noise prediction codes that accurately predict spectral directivity for both cold and hot jets are highly sought both in industry and academia. Their formulation, whether based upon manipulations of the Navier-Stokes equations or upon heuristic arguments, require substantial experimental observation of jet turbulence statistics. Unfortunately, the statistics of most interest involve the space-time correlation of flow quantities, especially velocity. Until the last 10 years, all turbulence statistics were made with single-point probes, such as hotwires or laser Doppler anemometry. Particle image velocimetry (PIV) brought many new insights with its ability to measure velocity fields over large regions of jets simultaneously; however, it could not measure velocity at rates higher than a few fields per second, making it unsuitable for obtaining temporal spectra and correlations. The development of time-resolved PIV, herein called TR-PIV, has removed this limitation, enabling measurement of velocity fields at high resolution in both space and time. In this paper, ground-breaking results from the application of TR-PIV to single-flow hot jets are used to explore the impact of heat on turbulent statistics of interest to jet noise models. First, a brief summary of validation studies is reported, undertaken to show that the new technique produces the same trusted results as hotwire at cold, low-speed jets. Second, velocity spectra from cold and hot jets are compared to see the effect of heat on the spectra. It is seen that heated jets possess 10 percent more turbulence intensity compared to the unheated jets with the same velocity. The spectral shapes, when normalized using Strouhal scaling, are insensitive to temperature if the stream-wise location is normalized relative to the potential core length. Similarly, second order velocity correlations, of interest in modeling of jet noise sources, are also insensitive to temperature as well.

  1. High precision radial velocities with GIANO spectra

    NASA Astrophysics Data System (ADS)

    Carleo, I.; Sanna, N.; Gratton, R.; Benatti, S.; Bonavita, M.; Oliva, E.; Origlia, L.; Desidera, S.; Claudi, R.; Sissa, E.

    2016-03-01

    Radial velocities (RV) measured from near-infrared (NIR) spectra are a potentially excellent tool to search for extrasolar planets around cool or active stars. High resolution infrared (IR) spectrographs now available are reaching the high precision of visible instruments, with a constant improvement over time. GIANO is an infrared echelle spectrograph at the Telescopio Nazionale Galileo (TNG) and it is a powerful tool to provide high resolution spectra for accurate RV measurements of exoplanets and for chemical and dynamical studies of stellar or extragalactic objects. No other high spectral resolution IR instrument has GIANO's capability to cover the entire NIR wavelength range (0.95-2.45 μm) in a single exposure. In this paper we describe the ensemble of procedures that we have developed to measure high precision RVs on GIANO spectra acquired during the Science Verification (SV) run, using the telluric lines as wavelength reference. We used the Cross Correlation Function (CCF) method to determine the velocity for both the star and the telluric lines. For this purpose, we constructed two suitable digital masks that include about 2000 stellar lines, and a similar number of telluric lines. The method is applied to various targets with different spectral type, from K2V to M8 stars. We reached different precisions mainly depending on the H-magnitudes: for H ˜ 5 we obtain an rms scatter of ˜ 10 m s-1, while for H ˜ 9 the standard deviation increases to ˜ 50 ÷ 80 m s-1. The corresponding theoretical error expectations are ˜ 4 m s-1 and 30 m s-1, respectively. Finally we provide the RVs measured with our procedure for the targets observed during GIANO Science Verification.

  2. Multifractal spectra in homogeneous shear flow

    NASA Technical Reports Server (NTRS)

    Deane, A. E.; Keefe, L. R.

    1988-01-01

    Employing numerical simulations of 3-D homogeneous shear flow, the associated multifractal spectra of the energy dissipation, scalar dissipation and vorticity fields were calculated. The results for (128) cubed simulations of this flow, and those obtained in recent experiments that analyzed 1- and 2-D intersections of atmospheric and laboratory flows, are in some agreement. A two-scale Cantor set model of the energy cascade process which describes the experimental results from 1-D intersections quite well, describes the 3-D results only marginally.

  3. Fine structure in cosmic ray spectra

    NASA Astrophysics Data System (ADS)

    Wolfendale, A. W.; Erlykin, A. D.

    2013-02-01

    The case is made for there being more 'structure' in the cosmic ray energy spectra than just the well-known knee at several PeV and the ankle at several EeV. Specifically, there seems to be a 'dip' or 'kink' at about 100 GeV/nucleon, a possible 'bump' at about 10 TeV, an 'iron peak' at 60 PeV and the possibility of further structure before the ankle is reached. The significance of the structures will be assessed.

  4. Far-infrared spectra of acetanilide revisited

    NASA Astrophysics Data System (ADS)

    Spire, A.; Barthes, M.; Kellouai, H.; De Nunzio, G.

    2000-03-01

    A new investigation of the temperature dependence of the far-infrared spectra of acetanilide and some isotopomers is presented. Four absorption bands are considered at 31, 42, 64, and 80 cm-1, and no significant change of their integrated intensity is observed when reducing the temperature. The temperature induced frequency shift values and other properties of these bands are consistent with an assignment as anharmonic lattice phonons. These results rule out the assignment of the 64, 80, and 106 cm-1 bands as normal modes of the polaronic excitation, as previously suggested.

  5. Ultraviolet absorption spectra of mercuric halides.

    NASA Technical Reports Server (NTRS)

    Templet, P.; Mcdonald, J. R.; Mcglynn, S. P.; Kendrow, C. H.; Roebber, J. L.; Weiss, K.

    1972-01-01

    The gas phase transitions of the mercuric halides were observed in the UV region by operating at temperatures above 400 K and at vapor pressures on the order of 0.5 mm. Spectral features exhibited by the chloride, bromide, and iodide of mercury correlate energetically with bands previously designated as intermolecular charge transfer transitions. The solution spectra of mercuric iodide and deep color of the crystals (if not due to some solid state interactions) indicate that this molecule may also have longer wavelength transitions.

  6. Isotopic spectra of the hydroxyl radical.

    PubMed

    Drouin, Brian J

    2013-10-01

    Rotational spectra of OH and its isotopologues have been precisely measured using high efficiency terahertz (THz) sources. The measurements are compared with existing data and are useful for global modeling. For the first time, microwave measurements of the Λ-doubling transitions of the (17)OH isotopologue are combined with THz data successfully. Precise rotational, fine-structure, and hyperfine structure parameters for the (17)OH isotopologue are reported. An isotopically independent Dunham model for all isotopologues of (2)Π OH v < 3 is presented. PMID:23634899

  7. Beamstrahlung spectra in next generation linear colliders

    SciTech Connect

    Barklow, T.; Chen, P. ); Kozanecki, W. )

    1992-04-01

    For the next generation of linear colliders, the energy loss due to beamstrahlung during the collision of the e{sup +}e{sup {minus}} beams is expected to substantially influence the effective center-of-mass energy distribution of the colliding particles. In this paper, we first derive analytical formulae for the electron and photon energy spectra under multiple beamstrahlung processes, and for the e{sup +}e{sup {minus}} and {gamma}{gamma} differential luminosities. We then apply our formulation to various classes of 500 GeV e{sup +}e{sup {minus}} linear collider designs currently under study.

  8. Benford's law and complex atomic spectra.

    PubMed

    Pain, Jean-Christophe

    2008-01-01

    We found that in transition arrays of complex atomic spectra, the strengths of electric-dipolar lines obey Benford's law, which means that their significant digits follow a logarithmic distribution favoring the smallest values. This indicates that atomic processes result from the superposition of uncorrelated probability laws and that the occurrence of digits reflects the constraints induced by the selection rules. Furthermore, Benford' law can be a useful test of theoretical spectroscopic models. Its applicability to the statistics of electric-dipolar lines can be understood in the framework of random matrix theory and is consistent with the Porter-Thomas law. PMID:18351894

  9. Impedance spectra of polypyrrole coated platinum electrodes.

    PubMed

    Onnela, Niina; Savolainen, Virpi; Hiltunen, Maiju; Kellomäki, Minna; Hyttinen, Jari

    2013-01-01

    Polypyrrole (PPy) coated electrodes may provide new solutions to increase the charge injection capacity and biocompatibility of metal electrodes in e.g., neural stimulus applications. In this study, electrical impedance spectra of PPy coated platinum (Pt) electrodes having three different coating thicknesses were measured and modeled. A suitable equivalent electrical circuit providing the material characteristics was chosen and the impedance data was analyzed using the model and data fitting. The modeled parameter values of different coating thicknesses were compared and our results demonstrated the changes in charge transfer properties and mechanisms of thin and thick PPy film coatings. PMID:24109743

  10. SPECTRA AND LIGHT CURVES OF FAILED SUPERNOVAE

    SciTech Connect

    Fryer, Chris L.; Dahl, Jon A.; Fontes, Christopher J. E-mail: dahl@lanl.go

    2009-12-10

    Astronomers have proposed a number of mechanisms to produce supernova explosions. Although many of these mechanisms are now not considered primary engines behind supernovae (SNe), they do produce transients that will be observed by upcoming ground-based surveys and NASA satellites. Here, we present the first radiation-hydrodynamics calculations of the spectra and light curves from three of these 'failed' SNe: SNe with considerable fallback, accretion-induced collapse of white dwarfs, and energetic helium flashes (also known as type Ia SNe).

  11. Synthetic spectra of C2 in comets

    NASA Technical Reports Server (NTRS)

    Ahearn, M. F.

    1978-01-01

    With the key result of Krishna Swamy and O'Dell (1977), a complete fluorescence equilibrium calculation has been used to predict the detailed Swan-band spectrum in comets. A rotational Boltzmann temperature of approximately 3000 K and small changes in published molecular constants lead to a theoretical spectrum in excellent agreement with that observed. The Fox-Herzberg bands are predicted to be quite weak compared with previously observed ultraviolet features in cometary spectra. The Ballik-Ramsay bands should be observable in the near-infrared.

  12. Spectra of electron oscillations in magnetoplasmadynamic thruster

    NASA Astrophysics Data System (ADS)

    Kirdyashev, K. P.; Kubarev, Yu. V.

    2012-03-01

    The intensity and spectra of electron oscillations in magnetoplasmadynamic (MPD) thruster have been experimentally studied. Oscillatory regimes corresponding to various relations between the relative gradients of magnetic field, electron concentration, and residual gas pressure in the vacuum chamber of the experimental setup have been determined. Relationship between the regimes of excitation of electron oscillations, the formation of an azimuthal current, and a change in the plasma flow potential is revealed. Model notions about the instability of plasma flow on low- and high-frequency branches of electron oscillations are developed.

  13. Fluorescence spectra shape based dynamic thermometry

    NASA Astrophysics Data System (ADS)

    Liu, Liwang; Creten, Sebastiaan; Firdaus, Yuliar; Agustin Flores Cuautle, Jose Jesus; Kouyaté, Mansour; Van der Auweraer, Mark; Glorieux, Christ

    2014-01-01

    An entirely optical, dynamic thermometry technique based on the temperature dependence of a fluorescence spectrum is presented. Different from conventional intensity-based fluorescence thermometry, in this work, neural network recognition is employed to extract the sample temperature from the magnitude and shape of recorded fluorescence spectra. As a demonstration to determine the depth profile of dynamical temperature variations and of the thermal and optical properties of semitransparent samples, in-depth photothermally induced periodical temperature oscillations of a rhodamine B and copper chloride dyed glycerol sample were measured with an accuracy of 4.2 mK.Hz-1/2 and fitted well by a 1D thermal diffusion model.

  14. Covariance Analysis of Gamma Ray Spectra

    SciTech Connect

    Trainham, R.; Tinsley, J.

    2013-01-01

    The covariance method exploits fluctuations in signals to recover information encoded in correlations which are usually lost when signal averaging occurs. In nuclear spectroscopy it can be regarded as a generalization of the coincidence technique. The method can be used to extract signal from uncorrelated noise, to separate overlapping spectral peaks, to identify escape peaks, to reconstruct spectra from Compton continua, and to generate secondary spectral fingerprints. We discuss a few statistical considerations of the covariance method and present experimental examples of its use in gamma spectroscopy.

  15. Covariance analysis of gamma ray spectra

    SciTech Connect

    Trainham, R.; Tinsley, J.

    2013-01-15

    The covariance method exploits fluctuations in signals to recover information encoded in correlations which are usually lost when signal averaging occurs. In nuclear spectroscopy it can be regarded as a generalization of the coincidence technique. The method can be used to extract signal from uncorrelated noise, to separate overlapping spectral peaks, to identify escape peaks, to reconstruct spectra from Compton continua, and to generate secondary spectral fingerprints. We discuss a few statistical considerations of the covariance method and present experimental examples of its use in gamma spectroscopy.

  16. Simulation and evaluation of nuclear reaction spectra

    NASA Astrophysics Data System (ADS)

    Vizkelethy, G.

    1990-01-01

    A RUMP-like-[1] computer code was written for PCs in order to simulate and evaluate nuclear reaction spectra. The code was written in Turbo Pascal. Any particle-target combination can be used; the stopping power calculation based on the ZBL algorithm [2] and the cross sections are taken from experimental data. The effects of straggling and geometrical spread are included in the simulation. Examples are given for the 16O(d,P) 17O, 18O(P,α) 15N, 16O( 3He,α) 15O and 16O(α,α) 16O reactions and for ERDA measurements.

  17. Applying Zeeman Doppler imaging to solar spectra

    NASA Astrophysics Data System (ADS)

    Hussain, G. A. J.; Saar, S. H.; Collier Cameron, A.

    2004-03-01

    A new generation of spectro-polarimeters with high throughput (e.g. CFHT/ESPADONS and LBT/PEPSI) is becoming available. This opportunity can be exploited using Zeeman Doppler imaging (ZDI), a technique that inverts time-series of Stokes V spectra to map stellar surface magnetic fields (Semel 1989). ZDI is assisted by ``Least squares deconvolution'' (LSD), which sums up the signal from 1000's of photospheric lines to produce a mean deconvolved profile with higher S:N (Donati & Collier Cameron 1997).

  18. Removing The Instrument Function From Fluorescence Spectra

    NASA Astrophysics Data System (ADS)

    Childs, Andrew F.

    1989-05-01

    The spectrum acquired at the sample phototnultiplier tube of a fluorescence spectrophotometer is a product of the sample spectrum and the instrument function. The determination of the instrument function and its removal from the acquired spectrum is often critical to the accurate determination of the physical properties of the sample. Methods are discussed for the determination and removal of the instrument function from excitation and emission spectra. Methods considered include quantum counters and ratio circuits for excitation correction, and emission correction against calibrated excitation systems, calibrated tungsten lamps, and NBS standard quinine sulfate.

  19. Glow Sticks: Spectra and Color Mixing

    NASA Astrophysics Data System (ADS)

    Birriel, Jennifer; Birriel, Ignacio

    2014-10-01

    Glow sticks are a popular Halloween staple familiar to most of our students. The production of light via a chemical reaction is called "chemiluminescence," and glow sticks are often used as demonstrations and experiments in the chemistry classroom to study reaction rates as a function of temperature.1-3 A black light can be used to illuminate glow sticks that have not been cracked or those that are "dead" in order to demonstrate fluorescence in liquid chemicals.4 In this article, we present the use of glow sticks as an inexpensive demonstration of spectra and color addition.

  20. Solar Doppler shifts - Sources of continuous spectra

    NASA Technical Reports Server (NTRS)

    Duvall, T. L., Jr.; Harvey, J. W.

    1986-01-01

    Oscillation observations can be used to study nonoscillatory solar phenomena that exhibit Doppler shifts. The paper discusses several effects of these phenomena and their associated temporal and spatial power spectra: (1) they limit the signal-to-noise ratio and sometimes detectability of oscillation modes; (2) there is the potential for better understanding and/or detection of solar phenomena; (3) large-scale convection may spatially modulate oscillation modes, leading to a continuous background spectrum; and (4) in regions of the spectrum where the resolution to separate modes is lacking one can determine upper limits for the integrated effects of modes.

  1. Magnetic Resonance Spectra and Statistical Geometry.

    PubMed

    Earle, Keith A; Mainali, Laxman; Sahu, Indra Dev; Schneider, David J

    2010-01-01

    Methods of statistical geometry are introduced which allow one to estimate, on the basis of computable criteria, the conditions under which maximally informative data may be collected. We note the important role of constraints which introduce curvature into parameter space and discuss the appropriate mathematical tools for treating curvature effects. Channel capacity, a term from communication theory, is suggested as a useful figure of merit for estimating the information content of spectra in the presence of noise. The tools introduced here are applied to the case of a model nitroxide system as a concrete example, but we stress that the methods described here are of general utility. PMID:20730032

  2. Vibrational infrared and raman spectra of dicyanoacetylene

    NASA Astrophysics Data System (ADS)

    Khanna, R. K.; Perera-Jarmer, M. A.; Ospina, M. J.

    The raman and infrared spectra for solid C 4N 2 are reported. New assignments are given for ˜gn 1 (2333 cm -1), ˜gn 2 (2267) and ˜gn 3 (640 cm -1). These assignments are supported by a normal coordinate Analysis using eight force constants. Extinction coefficients for the infrared active fundamentals are also reported. Our results suggest C 4N 2 to be a likely candidate to explain the 478 cm -1 band in the Titan's emission recorded by the Voyager mission.

  3. Theoretical photoabsorption spectra of Ar n+ clusters

    NASA Astrophysics Data System (ADS)

    Doltsinis, Nikos L.; Knowles, Peter J.

    2000-08-01

    The photoabsorption spectra of selected Ar n+ clusters ( n=7, 8, 17, 19, 23) have been investigated theoretically using an extended Diatomics-in-Molecules approach including induced dipole - induced dipole and spin-orbit coupling interaction effects. Our calculations at 0 K confirm the experimentally observed spectral red-shift of the visible photoabsorption peak in the region 15< n<20 [Levinger et al., J. Chem. Phys. 89 (1988) 5654]. Furthermore, we have been able to reproduce the additional red-shift measured for 7⩽ n⩽9 [Haberland et al., Phys. Rev. Lett. 67 (1991) 3290] by carrying out finite temperature Monte Carlo simulations.

  4. Raman spectra of hydroxide-halide melts

    NASA Astrophysics Data System (ADS)

    Zakiriyanova, I. D.; Khokhlov, V. A.

    2012-08-01

    The Raman spectra of molten binary mixtures based on sodium hydroxide and containing (mol %) 35 NaCl, 30 NaBr, and 30 NaI have been recorded at various temperatures. An increase in the vibrational frequency and the force constant of the O-H bond is detected under isothermal conditions upon a variation of the anionic composition of a melt in the series I → Br → Cl. Based on the experimental data, the viscosity of the hydroxide-halide melts is estimated.

  5. Ultraviolet Spectra of Normal Spiral Galaxies

    NASA Technical Reports Server (NTRS)

    Kinney, Anne

    1997-01-01

    The data related to this grant on the Ultraviolet Spectra of Normal Spiral Galaxies have been entirely reduced and analyzed. It is incorporated into templates of Spiral galaxies used in the calculation of K corrections towards the understanding of high redshift galaxies. The main paper was published in the Astrophysical Journal, August 1996, Volume 467, page 38. The data was also used in another publication, The Spectral Energy Distribution of Normal Starburst and Active Galaxies, June 1997, preprint series No. 1158. Copies of both have been attached.

  6. Magnetic Resonance Spectra and Statistical Geometry

    PubMed Central

    Mainali, Laxman; Sahu, Indra Dev; Schneider, David J.

    2010-01-01

    Methods of statistical geometry are introduced which allow one to estimate, on the basis of computable criteria, the conditions under which maximally informative data may be collected. We note the important role of constraints which introduce curvature into parameter space and discuss the appropriate mathematical tools for treating curvature effects. Channel capacity, a term from communication theory, is suggested as a useful figure of merit for estimating the information content of spectra in the presence of noise. The tools introduced here are applied to the case of a model nitroxide system as a concrete example, but we stress that the methods described here are of general utility. PMID:20730032

  7. Classification of specialty seed meals from NIR reflectance spectra

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Near infrared reflectance spectroscopy was used to identify alternative seed meals proposed for food and feed formulations. Spectra were collected from cold pressed Camelina (Camelina sativa), Coriander (Coriandrum sativum), and Pennycress (Thlaspi arvense) meals. Additional spectra were collected ...

  8. Quantum synchrotron spectra from semirelativistic electrons in teragauss magnetic fields

    NASA Technical Reports Server (NTRS)

    Brainerd, J. J.

    1987-01-01

    Synchrotron spectra are calculated from quantum electrodynamic transition rates for thermal and power-law electron distributions. It is shown that quantum effects appear in thermal spectra when the photon energy is greater than the electron temperature, and in power-law spectra when the electron energy in units of the electron rest mass times the magnetic field strength in units of the critical field strength is of order unity. These spectra are compared with spectra calculated from the ultrarelativistic approximation for synchrotron emission. It is found that the approximation for the power-law spectra is good, and the approximation for thermal spectra produces the shape of the spectrum accurately but fails to give the correct normalization. Single photon pair creation masks the quantum effects for power-law distributions, so only modifications to thermal spectra are important for gamma-ray bursts.

  9. Microwave Spectra of Furazan. IV. Rotation Spectra of Vibrationally Excited States of Perdeuterated Furazan

    NASA Astrophysics Data System (ADS)

    Stiefvater, Otto L.

    1990-10-01

    The pure rotation spectra of molecules in 25 vibrationally excited states of perdeuterated furazan, C2D2N2O, have been studied by double resonance modulation (DRM) microwave spectroscopy. Twelve of these spectra have been correlated, -on the basis of relative intensity measurements under DRM -, with fundamental vibrations as previously established by IR spectroscopy. Rotational parameters for these 12 fundamental levels are reported, and the contributions to the effective rotational constants and to the inertia defect of the ground state of d2 -furazan have been determined for 10 modes of vibration.

  10. Absorption Features in Soil Spectra Assessment.

    PubMed

    Vašát, Radim; Kodešová, Radka; Borůvka, Luboš; Jakšík, Ondřej; Klement, Aleš; Drábek, Ondřej

    2015-12-01

    From a wide range of techniques appropriate to relate spectra measurements with soil properties, partial least squares (PLS) regression and support vector machines (SVM) are most commonly used. This is due to their predictive power and the availability of software tools. Both represent exclusively statistically based approaches and, as such, benefit from multiple responses of soil material in the spectrum. However, physical-based approaches that focus only on a single spectral feature, such as simple linear regression using selected continuum-removed spectra values as a predictor variable, often provide accurate estimates. Furthermore, if this approach extends to multiple cases by taking into account three basic absorption feature parameters (area, width, and depth) of all occurring features as predictors and subjecting them to best subset selection, one can achieve even higher prediction accuracy compared with PLS regression. Here, we attempt to further extend this approach by adding two additional absorption feature parameters (left and right side area), as they can be important diagnostic markers, too. As a result, we achieved higher prediction accuracy compared with PLS regression and SVM for exchangeable soil pH, slightly higher or comparable for dithionite-citrate and ammonium oxalate extractable Fe and Mn forms, but slightly worse for oxidizable carbon content. Therefore, we suggest incorporating the multiple linear regression approach based on absorption feature parameters into existing working practices. PMID:26555184

  11. INFRARED SPECTRA OF AMMONIA-WATER ICES

    SciTech Connect

    Zheng Weijun; Jewitt, David; Kaiser, Ralf I. E-mail: ralfk@hawaii.edu

    2009-03-15

    We conducted a systematic study of the near-IR and mid-IR spectra of ammonia-water ices at various NH{sub 3}/H{sub 2}O ratios. The differences between the spectra of amorphous and crystalline ammonia-water ices were also investigated. The 2.0 {mu}m ammonia band central wavelength is a function of the ammonia/water ratio. It shifts from 2.006 {+-} 0.003 {mu}m (4985 {+-} 5 cm{sup -1}) to 1.993 {+-} 0.003 {mu}m (5018 {+-} 5 cm{sup -1}) as the percentage of ammonia decreases from 100% to 1%. The 2.2 {mu}m ammonia band center shifts from 2.229 {+-} 0.003 {mu}m (4486 {+-} 5 cm{sup -1}) to 2.208 {+-} 0.003 {mu}m (4528 {+-} 5 cm{sup -1}) over the same range. Temperature-dependent shifts of those bands are below the uncertainty of the measurement, and therefore are not detectable. These results are important for comparison with astronomical observations as well as for estimating the concentration of ammonia in outer solar system ices.

  12. Infrared Spectra of Substituted Polycyclic Aromatic Hydrocarbons

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Hudgins, Douglas M.; Sandford, Scott A.; Allamandola, Louis J.; Arnold, James O. (Technical Monitor)

    1997-01-01

    Calculations are carried out using density functional theory (DFT) to determine the harmonic frequencies and intensities of 1-methylanthracene, 9-methylanthracene, 9-cyanoanthracene, 2-aminoanthracene, acridine, and their positive ions. The theoretical data are compared with matrix-isolation spectra for these species also reported in this work. The theoretical and experimental frequencies and relative intensities for the neutral species are in generally good agreement, whereas the positive ion spectra are only in qualitative agreement. Relative to anthracene, we find that substitution of amethyl or CN for a hydrogen does not significantly affect the spectrum other than to add the characteristic methyl C-H stretch and C-N stretch (near 2200/cm), respectively. However, addition of NH2 dramatically affects the spectrum of the neutral. Not only are the NH2 modes themselves strong, but this electron withdrawing group induces sufficient partial charge on the ring to give the neutral molecule characteristics of the anthracene cation spectrum. The sum of the absolute intensities is about four times larger for 2-aminoanthracene than for 9-cyanoanthracene. Substituting nitrogen in the ring at the nine position (acridine) does not greatly alter the spectrum compared with anthracene.

  13. SEC Vidicon spectra of Geminid meteors, 1972

    NASA Technical Reports Server (NTRS)

    Millman, P. M.; Clifton, K. S.

    1975-01-01

    The SEC Vidicon, a low light level closed circuit television system, was used to obtain 137 spectrographic records of meteors at Mt. Hopkins, Arizona, during the Geminid meteor shower in December 1972. Seven of the best Geminid meteor spectra are studied here in detail. The near infrared, out to wavelengths near 9000 A, is recorded for the first time for Geminids. The spectra, in general, exhibit the elements previously found in photographic records of this shower but show a surprising frequency of occurrence of the forbidden green line of O I at 5577 A. This line is normally absent from meteors moving as slowly as the Geminids (36 km/sec) and its presence in these records may be due to the added sensitivity available with the SEC Vidicon. The average green line duration in Geminid meteors with a luminosity near zero absolute visual magnitude is 0.73 sec at a mean height of 95 km, 11 km lower than the green line peak in Perseid meteors of the same luminosity.

  14. Discriminating Dysarthria Type From Envelope Modulation Spectra

    PubMed Central

    Liss, Julie M.; LeGendre, Sue; Lotto, Andrew J.

    2013-01-01

    Purpose Previous research demonstrated the ability of temporally based rhythm metrics to distinguish among dysarthrias with different prosodic deficit profiles (J. M. Liss et al., 2009). The authors examined whether comparable results could be obtained by an automated analysis of speech envelope modulation spectra (EMS), which quantifies the rhythmicity of speech within specified frequency bands. Method EMS was conducted on sentences produced by 43 speakers with 1 of 4 types of dysarthria and healthy controls. The EMS consisted of the spectra of the slow-rate (up to 10 Hz) amplitude modulations of the full signal and 7 octave bands ranging in center frequency from 125 to 8000 Hz. Six variables were calculated for each band relating to peak frequency and amplitude and relative energy above, below, and in the region of 4 Hz. Discriminant function analyses (DFA) determined which sets of predictor variables best discriminated between and among groups. Results Each of 6 DFAs identified 2–6 of the 48 predictor variables. These variables achieved 84%–100% classification accuracy for group membership. Conclusions Dysarthrias can be characterized by quantifiable temporal patterns in acoustic output. Because EMS analysis is automated and requires no editing or linguistic assumptions, it shows promise as a clinical and research tool. PMID:20643800

  15. Measurement and interpretation of plutonium spectra

    SciTech Connect

    Blaise, J.; Fred, M.S.; Carnall, W.T.; Crosswhite, H.M.; Crosswhite, H.

    1983-01-01

    The atomic spectroscopic data available for plutonium are among the richest of any in the periodic system. They include high-resolution grating and Fourier-transform spectra as well as extensive Zeeman and isotope-shift studies. The present status of the term analysis is summarized, and the configurations that have been identified are cited. A least-squares adjustment of a parametric Hamiltonian for configurations of both Pu I and Pu II has shown that almost all of the expected low levels are now known. The use of a model Hamiltonian applicable to both lanthanide and actinide atomic species has been applied to the low configurations of Pu I and Pu II making use of trends predicted by ab initio calculations. This same model has been used to describe the energy levels of Pu/sup 3 +/ in LaCl/sub 3/, and an extension has permitted preliminary calculations of the spectra of other valence states. 46 references, 9 figures, 7 tables.

  16. Power spectra of internal gravity waves

    NASA Astrophysics Data System (ADS)

    Dewan, E. M.

    1990-09-01

    The OH layer located in the region of 85 km altitude emits strong infrared radiation. Gravity waves can be modulate the brightness of this layer over a wide range of spatial scales. Such fluctuations constitute, in effect, a form of IR clutter which could potentially degrade surveillance systems in certain situations. For this reason there is interest in the spatial and temporal variations of atmospheric internal gravity waves. A physical, similitude model of internal gravity waves assumes saturation of the waves and control by cascade processes of the temporal and horizontal scales of the waves. This model contains all the power spectral densities (PSD's) (sometimes merely called spectra) to be found in the formalism of Garrett and Munk. The latter is a purely empirical model for internal gravity waves applicable to the atmosphere and ocean. The main new predictions of the present model are that the dissipation rate controls the amplitudes of the frequency and horizontal wave number spectra. The validity of the proposed model is unknown at this time, and will depend upon the future experimental tests. It is shown, however, that based on 'typical' parametric values, results from the model are encouraging.

  17. Odor Impression Prediction from Mass Spectra

    PubMed Central

    Nakamoto, Takamichi

    2016-01-01

    The sense of smell arises from the perception of odors from chemicals. However, the relationship between the impression of odor and the numerous physicochemical parameters has yet to be understood owing to its complexity. As such, there is no established general method for predicting the impression of odor of a chemical only from its physicochemical properties. In this study, we designed a novel predictive model based on an artificial neural network with a deep structure for predicting odor impression utilizing the mass spectra of chemicals, and we conducted a series of computational analyses to evaluate its performance. Feature vectors extracted from the original high-dimensional space using two autoencoders equipped with both input and output layers in the model are used to build a mapping function from the feature space of mass spectra to the feature space of sensory data. The results of predictions obtained by the proposed new method have notable accuracy (R≅0.76) in comparison with a conventional method (R≅0.61). PMID:27326765

  18. Nuclear size effects in vibrational spectra.

    PubMed

    Almoukhalalati, Adel; Shee, Avijit; Saue, Trond

    2016-06-01

    We present a theoretical study of nuclear volume in the rovibrational spectra of diatomic molecules which is an extension of a previous study restricted to rotational spectra [Chem. Phys., 2012, 401, 103]. We provide a new derivation for the electron-nucleus electrostatic interaction energy which is basically independent of the choice of model for the nuclear charge distribution. Starting from this expression we derive expressions for the electronic, rotational and vibrational field shift parameters in terms of effective electron density and its first and second derivatives with respect to internuclear distance. The effective density is often approximated by the contact density, but we demonstrate that this leads to errors on the order of 10% and is furthermore not necessary since the contact and effective densities can be obtained at the same computational cost. We calculate the field shift parameters at the 4-component relativistic coupled-cluster singles-and-doubles level and find that our results confirm the experimental findings of Tiemann and co-workers [Chem. Phys., 1982, 68(21), 1982, Ber. Bunsenges. Phys. Chem., 1982, 86, 821], whereas we find no theoretical justification for a scaling factor introduced in later work [Chem. Phys., 1985, 93, 349]. For lead sulfide we study the effective density as a function of internuclear distance and find a minimum some 0.2 Å inside the equilibrium bond distance. We also discuss Bigeleisen-Goeppert-Mayer theory of isotope fractionation in light of our results. PMID:27215395

  19. 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.

  20. Classification of infrared spectra from skin tumors

    NASA Astrophysics Data System (ADS)

    McIntosh, Laura M.; Mansfield, James R.; Crowson, A. Neil; Toole, John W. P.; Mantsch, Henry H.; Jackson, Michael

    2000-05-01

    The clinical differential diagnosis of skin tumors is an often-challenging task, to which the probing of skin with mid- and near-infrared (IR) light may be contributory. The development of objective methods for the analysis of IR spectra remains a major hurdle to developing clinically useful applications. The authors highlight different processing methods for IR spectra from skin biopsies and in-vivo skin tumors. Spectroscopic maps of biopsies of basal cell, squamous cell and melanocytic neoplasms were objectively grouped into distinct clusters that corresponded with tumor, epidermis, dermis, follicle and fat. Normal and abnormal skin components were located within maps using a search engine based upon linear discriminant analysis (LDA). In all instances, areas of tumor were distinct from normal tissue in biopsies. In-vivo, near-IR spectroscopy and LDA allowed discrimination between benign and malignant skin lesions with a high degree of accuracy. We conclude that IR spectroscopy has significant diagnostic promise in the skin cancer arena. The analytical methods described can now be used to create a powerful classification scheme in which to detect skin tumor cells within biopsied and living skin.

  1. The energy spectra of solar flare electrons

    NASA Technical Reports Server (NTRS)

    Evenson, P. A.; Hovestadt, D.; Meyer, P.; Moses, D.

    1985-01-01

    A survey of 50 electron energy spectra from .1 to 100 MeV originating from solar flares was made by the combination of data from two spectrometers onboard the International Sun Earth Explorer-3 spacecraft. The observed spectral shapes of flare events can be divided into two classes through the criteria of fit to an acceleration model. This standard two step acceleration model, which fits the spectral shape of the first class of flares, involves an impulsive step that accelerates particles up to 100 keV and a second step that further accelerates these particles up to 100 MeV by a single shock. This fit fails for the second class of flares that can be characterized as having excessively hard spectra above 1 MeV relative to the predictions of the model. Correlations with soft X-ray and meter radio observations imply that the acceleration of the high energy particles in the second class of flares is dominated by the impulsive phase of the flares.

  2. Primordial spectra from sudden turning trajectory

    SciTech Connect

    Noumi, Toshifumi; Yamaguchi, Masahide E-mail: gucci@phys.titech.ac.jp

    2013-12-01

    Effects of heavy fields on primordial spectra of curvature perturbations are discussed in inflationary models with a sudden turning trajectory. When heavy fields are excited after the sudden turn and oscillate around the bottom of the potential, the following two effects are generically induced: deformation of the inflationary background spacetime and conversion interactions between adiabatic and isocurvature perturbations, both of which can affect the primordial density perturbations. In this paper, we calculate primordial spectra in inflationary models with sudden turning potentials taking into account both of the two effects appropriately. We find that there are some non-trivial correlations between the two effects in the power spectrum and, as a consequence, the primordial scalar power spectrum has a peak around the scale exiting the horizon at the turn. Though both effects can induce parametric resonance amplifications, they are shown to be canceled out for the case with the canonical kinetic terms. The peak feature and the scale dependence of bispectra are also discussed.

  3. Spectra of {gamma} rays feeding superdeformed bands

    SciTech Connect

    Lauritsen, T.; Khoo, T.L.; Henry, R.G.

    1995-08-01

    The spectrum of {gamma}rays coincident with SD transitions contains the transitions which populate the SD band. This spectrum can provide information on the feeding mechanism and on the properties (moment of inertia, collectivity) of excited SD states. We used a model we developed to explain the feeding of SD bands, to calculate the spectrum of feeding {gamma}rays. The Monte Carlo simulations take into account the trigger conditions present in our Eurogam experiment. Both experimental and theoretical spectra contain a statistical component and a broad E2 peak (from transitions occurring between excited states in the SD well). There is good resemblance between the measured and calculated spectra although the calculated multiplicity of an E2 bump is low by {approximately}30%. Work is continuing to improve the quality of the fits, which will result in a better understanding of excited SD states. In addition, a model for the last steps, which cool the {gamma} cascade into the SD yrast line, needs to be developed. A strong M1/E2 low-energy component, which we believe is responsible for this cooling, was observed.

  4. Millimeter wave absorption spectra of biological samples

    SciTech Connect

    Gandhi, O.P.; Hagmann, M.J.; Hill, D.W.; Partlow, L.M.; Bush, L.

    1980-01-01

    A solid-state computer-controlled system has been used to make swept-frequency measurements of absorption of biological specimens from 26.5 to 90.0 GHz. A wide range of samples was used, including solutions of DNA and RNA, and suspensions of BHK-21/C13 cells, Candida albicans, C krusei, and Escherichia coli. Sharp spectra reported by other workers were not observed. The strong absorbance of water (10--30 dB/mm) caused the absorbance of all aqueous preparations that we examined to have a water-like dependence on frequency. Reduction of incident power (to below 1.0 microW), elimination of modulation, and control of temperature to assure cell viability were not found to significantly alter the water-dominated absorbance. Frozen samples of BHK-21/C13 cells tested at dry ice and liquid nitrogen temperatures were found to have average insertion loss reduced to 0.2 dB/cm but still showed no reproducible peaks that could be attributed to absorption spectra. It is concluded that the special resonances reported by others are likely to be in error.

  5. High Resolution Infrared Spectra of Triacetylene

    NASA Astrophysics Data System (ADS)

    Doney, Kirstin D.; Zhao, Dongfeng; Linnartz, Harold

    2015-06-01

    Triacetylene, HC6H, is the longest poly-acetylene chain found in space, and is believed to be involved in the formation of longer chain molecules and polycyclic aromatic hydrocarbons (PAHs). However, abundances are expected to be low, and observational confirmation requires knowledge of the gas-phase spectra, which up to now has been incomplete with only the weak, low lying bending modes being known. We present new infrared (IR) spectra in the C-H stretch region obtained using ultra-sensitive and highly precise IR continuous wave cavity ring-down spectroscopy (cw-CRDS), combined with supersonic plasma expansions The talk reviews the accurate determination of the rotational constants of the asymmetric fundamental mode, νb{5}, including discussion on the perturber state, and associated hot bands. The determined molecular parameters are accurate enough to aid astronomical searches with such facilities as ALMA (Atacama Large Millimeter Array) or the upcoming JWST (James Webb Space Telecscope), which can now probe even trace molecules (abundances of ˜ 10-6 - 10-10 with respect to H2). D. Zhao, J. Guss, A. Walsh, H. Linnartz, Chem. Phys. Lett., 565, 132 (2013) K.D. Doney, D. Zhao, H. Linnartz, in preparation

  6. Microwave Spectra of 9-FLUORENONE and Benzophenone

    NASA Astrophysics Data System (ADS)

    West, Channing; Sedo, Galen; van Wijngaarden, Jennifer

    2015-06-01

    The pure rotational spectra of 9-fluorenone (C13H8O) and benzophenone (C13H10O) were observed using chirped-pulse Fourier transform microwave spectroscopy (cp-FTMW). The 9-fluorenone spectrum was collected between 8 and 13 GHz, which allowed for the assignment of 124 rotational transitions. A separate spectrum spanning from 8 to 14 GHz was collected for benzophenone, allowing for the assignment of 133 rotational transitions. Both aromatic ketones exhibited strong b-type spectra with little to no centrifugal distortion, indicating highly rigid molecular structures. A comparison of the experimentally determined spectral constants of 9-fluorenone to those calculated using both ab initio and density functional theory strongly suggest the molecule conforms to a planar C2v symmetric geometry as expected for its polycyclic structure. Whereas, a comparison of the experimental benzophenone constants to those predicted by theory suggests a molecule with non-planar C2 symmetry, where the two phenyl groups are rotated approximately 32° out-of-plane to form a paddlewheel like geometry.

  7. Odor Impression Prediction from Mass Spectra.

    PubMed

    Nozaki, Yuji; Nakamoto, Takamichi

    2016-01-01

    The sense of smell arises from the perception of odors from chemicals. However, the relationship between the impression of odor and the numerous physicochemical parameters has yet to be understood owing to its complexity. As such, there is no established general method for predicting the impression of odor of a chemical only from its physicochemical properties. In this study, we designed a novel predictive model based on an artificial neural network with a deep structure for predicting odor impression utilizing the mass spectra of chemicals, and we conducted a series of computational analyses to evaluate its performance. Feature vectors extracted from the original high-dimensional space using two autoencoders equipped with both input and output layers in the model are used to build a mapping function from the feature space of mass spectra to the feature space of sensory data. The results of predictions obtained by the proposed new method have notable accuracy (R≅0.76) in comparison with a conventional method (R≅0.61). PMID:27326765

  8. Blind Source Separation For Ion Mobility Spectra

    NASA Astrophysics Data System (ADS)

    Marco, S.; Pomareda, V.; Pardo, A.; Kessler, M.; Goebel, J.; Mueller, G.

    2009-05-01

    Miniaturization is a powerful trend for smart chemical instrumentation in a diversity of applications. It is know that miniaturization in IMS leads to a degradation of the system characteristics. For the present work, we are interested in signal processing solutions to mitigate limitations introduced by limited drift tube length that basically involve a loss of chemical selectivity. While blind source separation techniques (BSS) are popular in other domains, their application for smart chemical instrumentation is limited. However, in some conditions, basically linearity, BSS may fully recover the concentration time evolution and the pure spectra with few underlying hypothesis. This is extremely helpful in conditions where non-expected chemical interferents may appear, or unwanted perturbations may pollute the spectra. SIMPLISMA has been advocated by Harrington et al. in several papers. However, more modern methods of BSS for bilinear decomposition with the restriction of positiveness have appeared in the last decade. In order to explore and compare the performances of those methods a series of experiments were performed.

  9. Blind Source Separation For Ion Mobility Spectra

    SciTech Connect

    Marco, S.; Pomareda, V.

    2009-05-23

    Miniaturization is a powerful trend for smart chemical instrumentation in a diversity of applications. It is know that miniaturization in IMS leads to a degradation of the system characteristics. For the present work, we are interested in signal processing solutions to mitigate limitations introduced by limited drift tube length that basically involve a loss of chemical selectivity. While blind source separation techniques (BSS) are popular in other domains, their application for smart chemical instrumentation is limited. However, in some conditions, basically linearity, BSS may fully recover the concentration time evolution and the pure spectra with few underlying hypothesis. This is extremely helpful in conditions where non-expected chemical interferents may appear, or unwanted perturbations may pollute the spectra. SIMPLISMA has been advocated by Harrington et al. in several papers. However, more modern methods of BSS for bilinear decomposition with the restriction of positiveness have appeared in the last decade. In order to explore and compare the performances of those methods a series of experiments were performed.

  10. Serial FBG sensor network allowing overlapping spectra

    NASA Astrophysics Data System (ADS)

    Abbenseth, S.; Lochmann, S.; Ahrens, A.; Rehm, B.

    2016-05-01

    For structure or material monitoring low impact serial fiber Bragg grating (FBG) networks have attracted increasing research interest. Common sensor networks using wavelength division multiplexing (WDM) for FBG interrogation are limited in their efficiency by the spectral width of their light source, the FBG tuning range and the spectral guard bands. Overlapping spectra are strictly forbidden in this case. Applying time division multiplexing (TDM) or active resonator schemes may overcome these restrictions. However, they introduce other substantial disadvantages like signal roundtrip dependency or sophisticated control of active resonating structures. Code division multiplexing (CDM) as a means of FBG interrogation by simple autocorrelation of appropriate codes has been shown to be superior in this respect. However, it came at the cost of a second spectrometer introducing additional equalization efforts. We demonstrate a new serial FBG sensor network utilizing CDM signal processing for efficient sensor interrogation without the need of a second spectrometer and additional state of polarization (SOP) controlling components. It allows overlapping spectra even when all sensing FBGs are positioned at the same centre wavelength and it shows a high degree of insensitivity to SOP. Sequence inversed keyed (SIK) serial signal processing utilizing quasi-orthogonal balanced codes ensures simple and quick sensor interrogation with high signal-to-interference/noise ratio.

  11. Determination of antineutrino spectra from nuclear reactors

    SciTech Connect

    Huber, Patrick

    2011-08-15

    In this paper we study the effect of well-known higher-order corrections to the allowed {beta}-decay spectrum on the determination of antineutrino spectra resulting from the decays of fission fragments. In particular, we try to estimate the associated theory errors and find that induced currents like weak magnetism may ultimately limit our ability to improve the current accuracy and under certain circumstance could even greatly increase the theoretical errors. We also perform a critical evaluation of the errors associated with our method to extract the antineutrino spectrum using synthetic {beta} spectra. It turns out that a fit using only virtual {beta} branches with a judicious choice of the effective nuclear charge provides results with a minimal bias. We apply this method to actual data for {sup 235}U, {sup 239}Pu, and {sup 241}Pu and confirm, within errors, recent results, which indicate a net 3% upward shift in energy-averaged antineutrino fluxes. However, we also find significant shape differences which can, in principle, be tested by high-statistics antineutrino data samples.

  12. 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

  13. Stellar parametrization from Gaia RVS spectra

    NASA Astrophysics Data System (ADS)

    Recio-Blanco, A.; de Laverny, P.; Allende Prieto, C.; Fustes, D.; Manteiga, M.; Arcay, B.; Bijaoui, A.; Dafonte, C.; Ordenovic, C.; Ordoñez Blanco, D.

    2016-01-01

    Context. Among the myriad of data collected by the ESA Gaia satellite, about 150 million spectra will be delivered by the Radial Velocity Spectrometer (RVS) for stars as faint as GRVS~ 16. A specific stellar parametrization will be performed on most of these RVS spectra, i.e. those with enough high signal-to-noise ratio (S/N), which should correspond to single stars that have a magnitude in the RVS band brighter than ~14.5. Some individual chemical abundances will also be estimated for the brightest targets. Aims: We describe the different parametrization codes that have been specifically developed or adapted for RVS spectra within the GSP-Spec working group of the analysis consortium. The tested codes are based on optimisation (FERRE and GAUGUIN), projection (MATISSE), or pattern-recognition methods (Artificial Neural Networks). We present and discuss each of their expected performances in the recovered stellar atmospheric parameters (effective temperature, surface gravity, overall metallicity) for B- to K-type stars. The performances for determining of [α/Fe] ratios are also presented for cool stars. Methods: Each code has been homogeneously tested with a large grid of RVS simulated synthetic spectra of BAFGK-spectral types (dwarfs and giants), with metallicities varying from 10-2.5 to 10+ 0.5 the solar metallicity, and taking variations of ±0.4 dex in the composition of the α-elements into consideration. The tests were performed for S/N ranging from ten to 350. Results: For all the stellar types we considered, stars brighter than GRVS~ 12.5 are very efficiently parametrized by the GSP-Spec pipeline, including reliable estimations of [α/Fe]. Typical internal errors for FGK metal-rich and metal-intermediate stars are around 40 K in Teff, 0.10 dex in log(g), 0.04 dex in [M/H], and 0.03 dex in [α/Fe] at GRVS = 10.3. They degrade to 155 K in Teff, 0.15 dex in log(g), 0.10 dex in [M/H], and 0.1 dex in [α/Fe] at GRVS~ 12. Similar accuracies in Teff and [M/H] are

  14. Estimation of vertical sea level muon energy spectra from the latest primary cosmic ray elemental spectra

    NASA Astrophysics Data System (ADS)

    Mitra, M.; Molla, N. H.; Bhattacharyya, D. P.

    The directly measured elemental spectra of primary cosmic rays obtained from Webber et al., Seo et al., Menn et al., Ryan et al. and experiments like JACEE, CRN, SOKOL, RICH on P, He, CNO, Ne-S and Fe have been considered to estimate the vertical sea level muon energy spectra. The primary elemental energy spectra of P, He, CNO, Ne-S and Fe available from the different experimental data duly fitted by power law are given by Np(E)dE = 1.2216E-2.68 dE [cm2 .s.sr.GeV/n]-1 NHe(E)dE = 0.0424E-2.59 dE [cm2 .s.sr.GeV/n]-1 NCNO(E)dE = 0.0026E-2.57 dE[cm2 .s.sr.GeV/n]-1 NNe-S(E)dE = 0.00066E-2.57 dE [cm2 .s.sr.GeV/n]-1 NF e(E)dE = 0.0056E-2.55 dE [cm2 .s.sr.GeV/n]-1 Using the conventional superposition model the all nucleon primary cosmic ray spectrum has been derived which is of the form N(E)dE = 1.42E-2.66 dE [cm2 .s.sr.GeV/n]-1 We have considered all these spectra separately as parents of the secondary mesons and finallty the sea level muon fluxes at 00 from each species have been derived. To evaluate the meson spectra which are the initial air shower interaction products initiated by the primary nucleon air collisions, the hadronic energy moments have been calculated from the CERN LEBCEHS data for pp collisions and FNAL data for πp collisions. Pion production by secondary pions have been taken into account and the final total muon spectrum has been derived from pp rightarrowπ± x, pp → K± x, πp → π± x channels. The Z-factors have been corrected for p-air collisions. We have adopted the constant values of σp-air and σπ-air crosssections which are 273 mb and 213 mb, respectively. The adopted inelastic cross-sections for pp and πp interactions are 35 mb and 22 mb, respectively. The Q-G plasma correction of Z-factors have also been incorporated in the final form. The solution to the standard differential equation for mesons is considered for muon flux estimation from Ngenerations of the parent mesons. By this formulation vertical muon spectra from each element

  15. Mineral Spectra from Nili Fossae, Mars

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Spectra collected by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) indicate the presence of three distinct minerals. The graphed information comes from an observation of terrain in the Nili Fossae area of northern Mars. CRISM is one of six science instruments on NASA's Mars Reconnaissance Orbiter.

    Iron-magnesium smectite clay is formed through alteration of rocks by liquid water and is characterized by distinctive absorptions at 1.4, 1.9, and 2.3 micrometers due to water (H2O) and OH in the atomic structure of the mineral. Olivine is an iron magnesium silicate and primary igneous mineral, and water is not in its structure. Its spectrum is characterized by a strong and broad absorption at 1.0 micrometer due to ferrous iron (Fe2+). Carbonate is an alteration mineral identified by the distinctive paired absorptions at 2.3 and 2.5 micrometers. The precise band positions at 2.31 and 2.51 micrometers identify the carbonate at this location as magnesium carbonate. The broad 1.0 micrometer band indicates some small amount of ferrous iron is also present and the feature at 1.9 micrometers indicates the presence of water. CRISM researchers believe the magnesium carbonate found in the Nili Fossae region formed from alteration of olivine by water.

    The data come from a CRISM image catalogued as FRT00003E12. The spectra shown here are five-pixel-by-five-pixel averages of CRISM L-detector spectra taken from three different areas within the image that have then been ratioed to a five-pixel-by-five-pixel common denominator spectrum taken from a spectrally unremarkable area with no distinctive mineralogic signatures. This technique highlights the spectral contrasts between regions due to their unique mineralogy. The spectral wavelengths near 2.0 micrometers are affected by atmospheric absorptions and have been removed for clarity.

    NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, manages the Mars

  16. Automatic one dimensional spectra extraction for Weihai fiber-fed high resolution echelle spectra

    NASA Astrophysics Data System (ADS)

    Hu, Shao Ming; Gao, Dong Yang

    2014-11-01

    One fiber-fed high resolution echelle spectrograph was built for the one meter telescope atWeihai Observatory of Shandong University. It is used for exoplanet searching by radial velocity method and for stellar spectra analysis. One dimensional spectra extraction from the raw echelle data is researched in this paper. Flat field images with different exposure times were used to trace the order position accurately. The accurate background was fitted from each CCD image and it was subtracted from the raw image to correct the background and straylight. The intensity of each order decreases towards the order margin, and the lengths of order are different between the blue and red regions. The order tracing during the data reduction was investigated in this work. Accurate flux can be obtained after considering the effects of bad pixels, the curvature of each order and so on. One Interactive Data Language program for one dimensional spectra extraction was adopted and implemented to echelle data reduction for Weihai fiber-fed high resolution echelle spectra, and the results are illustrated here. The program is efficient and accurate for echelle data reduction. It can be adopted to reduce data taken by other instruments even the spectrographs in other fields, and it is very convenient for astronomers.

  17. IR SPECTRA BY DFT FOR GLUCOSE AND ITS EPIMERS: A COMPARISON BETWEEN VACUUM AND SOLVATED SPECTRA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Infrared spectra were calculated for the low energy geometry optimized structures of glucose and all of its epimers, at B3LYP/6-311++G** level of theory. Calculations were performed both in vacuo and using the COSMO solvation method. Frequencies, zero point energies, enthalpies, entropies, and rel...

  18. Vibrational spectra and molecular dynamics of alkoxycyanobiphenyls

    NASA Astrophysics Data System (ADS)

    Babkov, L. M.; Gabrusyonok, E.; Krasnoholovets, V. V.; Puchkovskaya, G. A.; Khakimov, I. N.

    1999-05-01

    The IR and Raman spectra of 4-alkoxy-4'-cyanobiphenyls ( nOCB, where n=3-8 is the number of carbon atom in the alkyl chain) were measured in the 30-3200 cm -1 spectral region at 77-400 K. With the DSC and DTA methods, the temperatures and enthalpies of the state transitions were determined for the substances under study in the 100-400 K temperature range. The changes of the spectral parameters of several vibrational bands at phase transitions were interpreted as being caused by conformational changes of the nOCB molecules. The mechanism of intradimer energy transfer which explains the Q(CN) band broadening in the liquid crystal and isotropic liquid phases is discussed.

  19. Workshop to establish databases of carbohydrate spectra

    SciTech Connect

    1995-12-31

    The workshop was organized to formulate guidelines for establishing spectral databases of complex carbohydrates. The databases will enable the scientific community to avoid the great waste of research effort and funds that frequently occurs when carbohydrate chemists are forced to duplicate the structural characterization of previously characterized complex carbohydrates. Chemists waste their effort on repetitive characterizations because in the absence of spectral databases they are unaware they are analyzing a known molecule until they have completely determined its structure. Chemists will be able to avoid much of this wasted effort when the collections of mass and of nuclear magnetic resonance (NMR) spectra initiated at the workshop are subsequently developed into searchable databases. Then scientists only need query the databases with the spectrum or with information defining the spectrum of an unidentified carbohydrate to find out if it has been previously characterized.

  20. Spectra as windows into exoplanet atmospheres.

    PubMed

    Burrows, Adam S

    2014-09-01

    Understanding a planet's atmosphere is a necessary condition for understanding not only the planet itself, but also its formation, structure, evolution, and habitability. This requirement puts a premium on obtaining spectra and developing credible interpretative tools with which to retrieve vital planetary information. However, for exoplanets, these twin goals are far from being realized. In this paper, I provide a personal perspective on exoplanet theory and remote sensing via photometry and low-resolution spectroscopy. Although not a review in any sense, this paper highlights the limitations in our knowledge of compositions, thermal profiles, and the effects of stellar irradiation, focusing on, but not restricted to, transiting giant planets. I suggest that the true function of the recent past of exoplanet atmospheric research has been not to constrain planet properties for all time, but to train a new generation of scientists who, by rapid trial and error, are fast establishing a solid future foundation for a robust science of exoplanets. PMID:24613929

  1. A Study of Pioneer Venus Nightglow Spectra

    NASA Technical Reports Server (NTRS)

    Slanger, Tom G.

    1993-01-01

    The work performed during the 12-month period of this contract involved: (1) further analysis of latitudinal variations in the Venusian NO nightglow intensity from PVOUVS data; (2) corrections made to the input data for the VTGCM model, relating specifically to a factor of three increase in the three-body recombination rate coefficient of N + O; (3) consideration of limits on the rate of reaction of N-atoms with CO2; (4) consideration of the Venusian equivalent of the terrestrial hot N-atom reaction for NO production; and (5) successful location of video images of meteor trails from space, for the purpose of making a comparison with the meteor trail that we have hypothesized as an explanation of intense UV spectra observed on a particular Pioneer Venus (PV) orbit.

  2. First dynamic spectra of stellar microwave flares

    NASA Technical Reports Server (NTRS)

    Bastian, T. S.; Bookbinder, J. A.

    1987-01-01

    The VLA has been used in the spectral-line mode at 1.4 GHz to obtain the first dynamic spectra of stellar sources other than the sun. Two very intense, highly circularly polarized, microwave outbursts were observed on the dMe flare star UV Cet, in addition to a slowly varying, unpolarized component. One outburst was purely left circularly polarized and showed no variations as a function of frequency across the 41 MHz band, whereas the other was as much as 70 percent right-circularly polarized and showed distinct variations with frequency. Although the slowly varying emission is probably due to incoherent gyrosynchrotron emission, the two flaring events are the result of coherent mechanisms. The coherent emission is interpreted in terms of plasma radiation and the cyclotron maser instability.

  3. Reflectance Spectra of the Juneau Icefield

    NASA Astrophysics Data System (ADS)

    Hughes-Allen, L.; Popyack, K.; Peter, A.; Perera, E.; Pope, A.

    2015-12-01

    Snow reflectance is an important input to understanding a glacier's surface energy balance. It is also useful for quantifying other snow properties such as impurities and grain size. In cooperation with the Juneau Icefield Research Program, we measured the spectral reflectance and albedo of a range of targets, collecting a spectral catalogue of the Taku glacier system. Using this spectral library, the main foci of this study are linking red algae biomass to spectral reflectance, quantifying the radiative forcing of impurities in suncups, and testing a snow grain size retrieval algorithm. Impurities, algae, and large snow grains all reduce the reflectance of shortwave radiation but with unique spectral signatures. In addition, spectra are used in conjunction with satellite imagery to investigate the spatial variability of albedo and therefore impurities on the Taku Glacier.

  4. UV Spectra, Bombs, and the Solar Atmosphere

    NASA Astrophysics Data System (ADS)

    Judge, Philip G.

    2015-08-01

    A recent analysis of UV data from the Interface Region Imaging Spectrograph (IRIS) reports plasma “bombs” with temperatures near 8 × 104 K within the solar photosphere. This is a curious result, first because most bomb plasma pressures p (the largest reported case exceeds 103 dyn cm-2) fall well below photospheric pressures (\\gt 7× {10}3), and second, UV radiation cannot easily escape from the photosphere. In the present paper the IRIS data is independently analyzed. I find that the bombs arise from plasma originally at pressures between ≤ 80 and 800 dyne cm-2 before explosion, i.e., between ≥ 850 and 550 km above {τ }500=1. This places the phenomenon’s origin in the low-mid chromosphere or above. I suggest that bomb spectra are more compatible with Alfvénic turbulence than with bi-directional reconnection jets.

  5. Galactic cosmic ray composition and energy spectra

    NASA Technical Reports Server (NTRS)

    Mewaldt, R. A.

    1994-01-01

    Galactic cosmic ray nuclei represent a significant risk to long-duration spaceflight outside the magnetosphere. We review briefly existing measurements of the composition and energy spectra of heavy cosmic ray nuclei, pointing out which species and energy ranges are most critical to assessing cosmic ray risks for spaceflight. Key data sets are identified and a table of cosmic ray abundances is presented for elements from H to Ni (Z = 1 to 28). Because of the 22-year nature of the solar modulation cycle, data from the approaching 1998 solar minimum is especially important to reducing uncertainties in the cosmic ray radiation hazard. It is recommended that efforts to model this hazard take advantage of approaches that have been developed to model the astrophysical aspects of cosmic rays.

  6. 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.

  7. On Magnetic Spectra of Earth and Mars

    NASA Technical Reports Server (NTRS)

    Voorhies, C. V.; Sabaka, T. J.; Purucker, M.

    2002-01-01

    The spectral method for distinguishing crustal from core-source magnetic fields is reexamined, modified, and applied to both a comprehensive geomagnetic field model and an altitude normalized magnetic map of Mars. The observational spectra are fairly fitted by theoretical forms expected from certain elementary classes of magnetic sources. For Earth we find fields from a core of radius 3512 +/- 64 km, in accord with the seismologic core radius of 3480 km, and a crust represented by a shell of random dipolar sources at radius 6367 +/- 14 km, near the planetary mean radius of 6371.2 km. For Mars we find no sign of a core-source field, only a field from a crust represented in same way, but at radius 3344 +/- 10 km, about 46 km below the planetary mean radius of 3389.5 km, and with sources about 9.6 +/- 3.2 times stronger.

  8. Evolution and infrared spectra of brown dwarfs

    NASA Technical Reports Server (NTRS)

    Lunine, Jonathan I.; Hubbard, William B.; Marley, Mark S.

    1986-01-01

    Self-consistent models are constructed for the structure, evolution, and observable properties of degenerately cooling objects, or 'brown dwarfs'. Model atmospheres composed of a range of likely gaseous and particulate opacity sources are calculated in order to provide a boundary condition for interior temperature-pressure profiles and to determine the emergent spectra for such objects. The radius derived from the interior models is combined with the emergent fluxes calculated from the atmosphere model to fit the data of McCarthy, Probst, and Low (1985) and to derive the luminosity and mass of VB 8B. The latter is found to be most probably an 0.05 solar mass object with effective temperature in the 1200-1500 K range and an atmosphere which very likely contains particulate absorbers. Key changes in chemical oxidation state and condensation of major constituents during the evolution of brown dwarfs are presented.

  9. Optical absorption spectra of dications of carotenoids

    SciTech Connect

    Jeevarajan, J.A.; Wei, C.C.; Jeevarajan, A.S.; Kispert, L.D.

    1996-04-04

    Quantitative optical absorption spectra of the cation radicals and the dications of canthaxanthin (I), {beta}carotene (II), 7`-cyano-7`-ethoxycarbonyl-7`-apo-{beta}-carotene (III), and 7`,7`-dimethyl-7`-apo-{beta}-carotene (IV) in dichloromethane solution are reported. Exclusive formation of dications occurs when the carotenoids are oxidized with ferric chloride. Addition of neutral carotenoid to the dications results in equilibrium formation of cation radicals. Oxidation with iodine in dichloromethane affords only cation radicals; electrochemical oxidation under suitable conditions yields both dications and cation radicals. Values of the optical parameters depend on the nature of the oxidative medium. The oscillator strengths calculated for gas phase cation radicals and dications of I-IV using the INDO/S method show the same trend as the experimental values. 31 refs., 4 figs., 2 tabs.

  10. Spectra as windows into exoplanet atmospheres

    NASA Astrophysics Data System (ADS)

    Burrows, Adam S.

    2014-09-01

    Understanding a planet's atmosphere is a necessary condition for understanding not only the planet itself, but also its formation, structure, evolution, and habitability. This requirement puts a premium on obtaining spectra and developing credible interpretative tools with which to retrieve vital planetary information. However, for exoplanets, these twin goals are far from being realized. In this paper, I provide a personal perspective on exoplanet theory and remote sensing via photometry and low-resolution spectroscopy. Although not a review in any sense, this paper highlights the limitations in our knowledge of compositions, thermal profiles, and the effects of stellar irradiation, focusing on, but not restricted to, transiting giant planets. I suggest that the true function of the recent past of exoplanet atmospheric research has been not to constrain planet properties for all time, but to train a new generation of scientists who, by rapid trial and error, are fast establishing a solid future foundation for a robust science of exoplanets.

  11. Jets and Bombs: Characterizing IRIS Spectra

    NASA Astrophysics Data System (ADS)

    Schmit, Donald; Innes, Davina

    2014-06-01

    For almost two decades, SUMER has provided an unique perspective on explosive events in the lower solar atmosphere. One of the hallmark observations during this tenure is the identification of quiet sun bi-directional jets in the lower transition region. We investigate these events through two distinct avenues of study: a MHD model for reconnection and the new datasets of the Interface Region Imaging Spectrograph (IRIS). Based on forward modeling optically thin spectral profiles, we find the spectral signatures of reconnection can vary dramatically based on viewing angle and altitude. We look to the IRIS data to provide a more complete context of the chromospheric and coronal environment during these dynamic events. During a joint IRIS-SUMER observing campaign, we observed spectra of multiple jets, a small C flare, and an Ellerman bomb event. We discuss the questions that arise from the inspection of these new data.

  12. Spectra of Particulate Backscattering in Natural Waters

    NASA Technical Reports Server (NTRS)

    Gordon, Howard, R.; Lewis, Marlon R.; McLean, Scott D.; Twardowski, Michael S.; Freeman, Scott A.; Voss, Kenneth J.; Boynton, Chris G.

    2009-01-01

    Hyperspectral profiles of downwelling irradiance and upwelling radiance in natural waters (oligotrophic and mesotrophic) are combined with inverse radiative transfer to obtain high resolution spectra of the absorption coefficient (a) and the backscattering coefficient (bb) of the water and its constituents. The absorption coefficient at the mesotrophic station clearly shows spectral absorption features attributable to several phytoplankton pigments (Chlorophyll a, b, c, and Carotenoids). The backscattering shows only weak spectral features and can be well represented by a power-law variation with wavelength (lambda): b(sub b) approx. Lambda(sup -n), where n is a constant between 0.4 and 1.0. However, the weak spectral features in b(sub b), suggest that it is depressed in spectral regions of strong particle absorption. The applicability of the present inverse radiative transfer algorithm, which omits the influence of Raman scattering, is limited to lambda < 490 nm in oligotrophic waters and lambda < 575 nm in mesotrophic waters.

  13. Microwave spectra of terrestrial mesospheric CO

    NASA Technical Reports Server (NTRS)

    Clancy, R. T.; Muhleman, D. O.; Berge, G. L.

    1982-01-01

    Mesospheric CO was observed in absorption against the moon in early December 1979 at a wavelength of 1.3 mm and in early December 1980 at 2.6 mm with the 10.4-m millimeter wavelength telescope at the Owens Valley Radio Observatory. No significant change in the column density of CO above about 65 km is found between the 1979 and 1980 observations. Comparison with other published spectra of mesospheric CO suggests a large seasonal variation (about a factor of 2-3) in the column density of CO above 65 km, with a maximum in winter and a minimum in summer. It is concluded that the understanding of CO in the mesosphere can be improved with earth-based microwave measurements, but data with high signal-to-noise ratios must be obtained.

  14. Universality of vibrational spectra of globular proteins.

    PubMed

    Na, Hyuntae; Song, Guang; ben-Avraham, Daniel

    2016-02-01

    It is shown that the density of modes of the vibrational spectrum of globular proteins is universal, i.e. regardless of the protein in question, it closely follows one universal curve. The present study, including 135 proteins analyzed with a full atomic empirical potential (CHARMM22) and using the full complement of all atoms Cartesian degrees of freedom, goes far beyond previous claims of universality, confirming that universality holds even in the frequency range that is well above 100 cm(-1) (300-4000 cm(-1)), where peaks and turns in the density of states are faithfully reproduced from one protein to the next. We also characterize fluctuations of the spectral density from the average, paving the way to a meaningful discussion of rare, unusual spectra and the structural reasons for the deviations in such 'outlier' proteins. Since the method used for the derivation of the vibrational modes (potential energy formulation, set of degrees of freedom employed, etc) has a dramatic effect on the spectral density, another significant implication of our findings is that the universality can provide an exquisite tool for assessing and improving the quality of potential functions and the quality of various models used for NMA computations. Finally, we show that the input configuration also affects the density of modes, thus emphasizing the importance of simplified potential energy formulations that are minimized at the outset. In summary, our findings call for a serious two-way dialogue between theory and experiment: experimental spectra of proteins could now guide the fine tuning of theoretical empirical potentials, and the various features and peaks observed in theoretical studies--being universal, and hence now rising in importance--would hopefully spur experimental confirmation. PMID:26907186

  15. High Pressure Oxygen A-Band Spectra

    NASA Astrophysics Data System (ADS)

    Drouin, Brian; Sung, Keeyoon; Yu, Shanshan; Lunny, Elizabeth M.; Bui, Thinh Quoc; Okumura, Mitchio; Rupasinghe, Priyanka; Bray, Caitlin; Long, David A.; Hodges, Joseph; Robichaud, David; Benner, D. Chris; Devi, V. Malathy; Hoo, Jiajun

    2015-06-01

    Composition measurements from remote sensing platforms require knowledge of air mass to better than the desired precision of the composition. Oxygen spectra allow determination of air mass since the mixing ratio of oxygen is fixed. The OCO-2 mission is currently retrieving carbon dioxide concentration using the oxygen A-band for air mass normalization. The 0.25% accuracy desired for the carbon dioxide concentration has pushed the state-of-the-art for oxygen spectroscopy. To produce atmospheric pressure A-band cross-sections with this accuracy requires a sophisticated line-shape model (Galatry or Speed-Dependent) with line mixing (LM) and collision induced absorption (CIA). Models of each of these phenomena exist, but an integrated self-consistent model must be developed to ensure accuracy. This presentation will describe the ongoing effort to parameterize these phenomena on a representative data set created from complementary experimental techniques. The techniques include Fourier transform spectroscopy (FTS), photo-acoustic spectroscopy (PAS) and cavity ring-down spectroscopy (CRDS). CRDS data allow long-pathlength measurements with absolute intensities, providing lineshape information as well as LM and CIA, however the subtleties of the lineshape are diminished in the saturated line-centers. Conversely, the short paths and large dynamic range of the PAS data allow the full lineshape to be discerned, but with an arbitrary intensity axis. Finally, the FTS data provides intermediate paths and consistency across a broad pressure range. These spectra are all modeled with the Labfit software using first the spectral line database HITRAN, and then model values are adjusted and fitted for better agreement with the data.

  16. Detecting the Baryons in Matter Power Spectra

    NASA Astrophysics Data System (ADS)

    Miller, Christopher J.; Nichol, Robert C.; Chen, Xuelei

    2002-11-01

    We examine power spectra from the Abell/ACO rich cluster survey and the Two-Degree Field Galaxy Redshift Survey (2dFGRS) for observational evidence of features produced by the baryons. A nonnegligible baryon fraction produces relatively sharp oscillatory features at specific wavenumbers in the matter power spectrum. However, the mere existence of baryons will also produce a global suppression of the power spectrum. We look for both of these features using the false discovery rate statistic. We show that the window effects on the Abell/ACO power spectrum are minimal, which has allowed for the discovery of discrete oscillatory features in the power spectrum. On the other hand, there are no statistically significant oscillatory features in the 2dFGRS power spectrum, which is expected from the survey's broad window function. After accounting for window effects we apply a scale-independent bias to the 2dFGRS power spectrum, PAbell(k)=b2P2dF(k) and b=3.2. We find that the overall shapes of the Abell/ACO and the biased 2dFGRS power spectra are entirely consistent over the range 0.02<=k<=0.15h Mpc-1. We examine the range of Ωmatter and baryon fraction, for which these surveys could detect significant suppression in power. The reported baryon fractions for both the Abell/ACO and 2dFGRS surveys are high enough to cause a detectable suppression in power (after accounting for errors, windows, and k-space sampling). Using the same technique, we also examine, given the best-fit baryon density obtained from big bang nucleosynthesis, whether it is possible to detect additional suppression due to dark matter-baryon interaction. We find that the limit on dark matter cross section/mass derived from these surveys is the same as those ruled out in a recent study by Chen, Hannestad, & Scherrer.

  17. Spectra of small Koronis family members

    NASA Astrophysics Data System (ADS)

    Thomas, C.; Rivkin, A.; Trilling, D.; Moskovitz, N.

    2014-07-01

    The space-weathering process and its implications for the relationships between S- and Q-type asteroids and ordinary chondrite meteorites are long-standing problems in asteroid science. Although the visible and near-infrared spectra of S- and Q-type objects qualitatively show the same absorption features and quantitatively show evidence of the same minerals, the S types display increased spectral slopes and muted absorption features compared to the Q types. This spectral mismatch is consistent with the effects of the space weathering process. Binzel et al. provided the missing link between Q- and S-type bodies in near-Earth space by showing a reddening of spectral slope in objects from 0.1 to 5 km that corresponded to the transition from Q- to S-type spectra. This result implied that size, and therefore age, is related to the relationship between Q- and S-type. The existence of Q-type objects in the main belt was not confirmed until Mothe-Diniz and Nesvorny (2008) found them in young S-type clusters. To investigate the trend from Q to S in the main belt, we examined space weathering within the old main-belt Koronis family using a spectrophotometric survey (Rivkin et al. 2011, Thomas et al. 2011). Rivkin et al. (2011) identified several potential Q-type objects within the Koronis family. Our Q-type candidates were identified using broad-band spectrophotometry and could not be taxonomically classified on that basis alone. We obtained follow-up visible and near-infrared spectral observations of our potential Q-type objects, (26970) Elias, (45610) 2000 DJ_{48}, and (37411) 2001 XF_{152}, using Gemini and Magellan. We will present the results of these spectral follow-up observations. Observations of (26970) Elias demonstrate that the object is more consistent with the average Q-type spectrum than the average S-type spectrum.

  18. 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.

  19. Universality of vibrational spectra of globular proteins

    NASA Astrophysics Data System (ADS)

    Na, Hyuntae; Song, Guang; ben-Avraham, Daniel

    2016-02-01

    It is shown that the density of modes of the vibrational spectrum of globular proteins is universal, i.e. regardless of the protein in question, it closely follows one universal curve. The present study, including 135 proteins analyzed with a full atomic empirical potential (CHARMM22) and using the full complement of all atoms Cartesian degrees of freedom, goes far beyond previous claims of universality, confirming that universality holds even in the frequency range that is well above 100 cm-1 (300-4000 cm-1), where peaks and turns in the density of states are faithfully reproduced from one protein to the next. We also characterize fluctuations of the spectral density from the average, paving the way to a meaningful discussion of rare, unusual spectra and the structural reasons for the deviations in such ‘outlier’ proteins. Since the method used for the derivation of the vibrational modes (potential energy formulation, set of degrees of freedom employed, etc) has a dramatic effect on the spectral density, another significant implication of our findings is that the universality can provide an exquisite tool for assessing and improving the quality of potential functions and the quality of various models used for NMA computations. Finally, we show that the input configuration also affects the density of modes, thus emphasizing the importance of simplified potential energy formulations that are minimized at the outset. In summary, our findings call for a serious two-way dialogue between theory and experiment: experimental spectra of proteins could now guide the fine tuning of theoretical empirical potentials, and the various features and peaks observed in theoretical studies—being universal, and hence now rising in importance—would hopefully spur experimental confirmation.

  20. 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){ν }{br} with a break frequency {ν }{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 {γ }{{e}}≳ {10}4.

  1. 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.

  2. 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){ν }{br} with a break frequency {ν }{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 {γ }{{e}}≳ {10}4.

  3. Prediction of electroencephalographic spectra from neurophysiology

    NASA Astrophysics Data System (ADS)

    Robinson, P. A.; Rennie, C. J.; Wright, J. J.; Bahramali, H.; Gordon, E.; Rowe, D. L.

    2001-02-01

    A recent neurophysical model of propagation of electrical waves in the cortex is extended to include a physiologically motivated subcortical feedback loop via the thalamus. The electroencephalographic spectrum when the system is driven by white noise is then calculated analytically in terms of physiological parameters, including the effects of filtering of signals by the cerebrospinal fluid, skull, and scalp. The spectral power at low frequencies is found to vary as f-1 when awake and f-3 when asleep, with a breakpoint to a steeper power-law tail at frequencies above about 20 Hz in both cases; the f-1 range concurs with recent magnetoencephalographic observations of such a regime. Parameter sensitivities are explored, enabling a model with fewer free parameters to be proposed, and showing that spectra predicted for physiologically reasonable parameter values strongly resemble those observed in the laboratory. Alpha and beta peaks seen near 10 Hz and twice that frequency, respectively, in the relaxed wakeful state are generated via subcortical feedback in this model, thereby leading to predictions of their frequencies in terms of physiological parameters, and of correlations in their occurrence. Subcortical feedback is also predicted to be responsible for production of anticorrelated peaks in deep sleep states that correspond to the occurrence of theta rhythm at around half the alpha frequency and sleep spindles at 3/2 times the alpha frequency. An additional positively correlated waking peak near three times the alpha frequency is also predicted and tentatively observed, as are two new types of sleep spindle near 5/2 and 7/2 times the alpha frequency, and anticorrelated with alpha. These results provide a theoretical basis for the conventional division of EEG spectra into frequency bands, but imply that the exact bounds of these bands depend on the individual. Three types of potential instability are found: one at zero frequency, another in the theta band at around

  4. Cooling Flow Spectra in Ginga Galaxy Clusters

    NASA Technical Reports Server (NTRS)

    White, Raymond E., III

    1997-01-01

    The primary focus of this research project has been a joint analysis of Ginga LAC and Einstein SSS X-ray spectra of the hot gas in galaxy clusters with cooling flows is reported. We studied four clusters (A496, A1795, A2142 & A2199) and found their central temperatures to be cooler than in the exterior, which is expected from their having cooling flows. More interestingly, we found central metal abundance enhancements in two of the clusters, A496 and A2142. We have been assessing whether the abundance gradients (or lack thereof) in intracluster gas is correlated with galaxy morphological gradients in the host clusters. In rich, dense galaxy clusters, elliptical and SO galaxies are generally found in the cluster cores, while spiral galaxies are found in the outskirts. If the metals observed in clusters came from proto-ellipticals and proto-S0s blowing winds, then the metal distribution in intracluster gas may still reflect the distribution of their former host galaxies. In a research project which was inspired by the success of the Ginga LAC/Einstein SSS work, we analyzed X-ray spectra from the HEAO-A2 MED and the Einstein SSS to look for temperature gradients in cluster gas. The HEAO-A2 MED was also a non-imaging detector with a large field of view compared to the SSS, so we used the differing fields of view of the two instruments to extract spatial information. We found some evidence of cool gas in the outskirts of clusters, which may indicate that the nominally isothermal mass density distributions in these clusters are steepening in the outer parts of these clusters.

  5. 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

  6. Spectra of volcanic rocks glasses as analogues of Mercury surface spectra

    NASA Astrophysics Data System (ADS)

    Carli, C.; Capaccioni, F.; de Sanctis, M.; Filacchione, G.; Sgavetti, M.; di Genova, D.; Vona, A.; Visonà, D.; Ammannito, E.

    2010-12-01

    Remote-sensing studies have revealed that most of the inner planets surfaces are composed by magmatic effusive rocks as lava flows or pyroclastic deposits, that are the natural products of magma-rock dynamic systems controlled by T, P, oxygen fugacity and time. These materials generally contain a fair amount of volcanic glass, due to the magma rapid cooling once effused on the surface. The VNIR reflectance spectroscopy is one of the most relevant tools for remote-sensing studies and in the last decades gave important results identifying the presence of different Fe-Mg silicates, such as olivine and pyroxenes, on the planets surfaces. However, the mineralogical interpretation of the observed spectral features of several volcanic areas on the inner Solar System bodies is still matter of debate. In particular the presence of dark volcanic glass, which can dominate or not the rock texture, influences the spectra signatures. In fact samples with a glass-bearing groundmass have lower albedo and reduced band intensity of the spectra of samples with comparable mineral composition and intergranular texture. As a consequence, an important goal for studying the planetary crusts is to understand the spectral behavior of volcanic material, where chemical or physical parameters are different depending on geologic context and effusive processes. We present here preliminary laboratory activity to investigate VNIR reflectance spectra of several volcanic glasses. Reflectance spectra, in the wavelength range between 0.35- 2.50 μm, are measured on powders of magmatic rocks, having different composition and textures, at fine (<60 μm in diameter) and very fine (<10 μm) grain sizes. For each rock sample a corresponding “thermal shocked-sample” is produced by heating at 1300°C and P=1 atm and a glass-sample was produced by melting at 1500°C and P=1 atm, than quenching it in air. Reflectance spectra of powders of shocked and glass-samples were acquired at the same grain size, and

  7. Browsing a wealth of millimeter-wavelength doppler spectra data

    SciTech Connect

    Johnson,K.; Luke,E.; Kollias, P.; Remillard, J.; Widener, K.; Jensen, M.

    2010-03-15

    The ARM Climate Research Facility has collected an extensive archive of vertically pointing millimeter wavelength Doppler radar spectra at both 35 and 95 GHz. These data are a rich potential source of detailed microphysical and dynamical cloud and precipitation information. The recording of spectra, which is ongoing, began at the Southern Great Plains site in September of 2003, at the North Slope of Alaska site in April 2004, and at Tropical Western Pacific sites in 2006. Spectra are also being collected during ARM Mobile Facility deployments. The data’s temporal resolution is as high as two seconds, at height intervals of 45 to 90 m. However, the sheer volume of available data can be somewhat daunting to access and search for specific features of interest. Here we present a user interface for spectra browsing, which allows the user to view time-height images of radar moments, select a time or height of interest, and then “drill down” through images of spectrograms to individual Doppler spectra or time- and height-sequences of spectra. Also available are images summarizing spectral characteristics, such as number of spectral peaks, spectral shape information (skewness and kurtosis), moment uncertainty estimates, and hydrometeor vs. clutter identification as produced by the ARM MicroARSCL (Microphysical Active Remote Sensing of Clouds) value-added product. In addition to the access and visualization tools, we are developing a Doppler spectra simulator capable of generating Doppler spectra from liquid, mixed-phase, and solid cloud constituents and precipitation. The Doppler spectra simulator can be used as an interface between explicit microphysics models and Doppler spectra observations from the ARM radars. The plan is to ultimately make the spectra simulator available from within the spectra browser, allowing a user to associate observed spectra with the microphysical conditions capable of producing them.

  8. Ab initio infrared and Raman spectra

    NASA Astrophysics Data System (ADS)

    Fredkin, Donald R.; Komornicki, Andrew; White, Steven R.; Wilson, Kent R.

    1983-06-01

    We discuss several ways in which molecular absorption and scattering spectra can be computed ab initio, from the fundamental constants of nature. These methods can be divided into two general categories. In the first, or sequential, type of approach, one first solves the electronic part of the Schrödinger equation in the Born-Oppenheimer approximation, mapping out the potential energy, dipole moment vector (for infrared absorption) and polarizability tensor (for Raman scattering) as functions of nuclear coordinates. Having completed the electronic part of the calculation, one then solves the nuclear part of the problem either classically or quantum mechanically. As an example of the sequential ab initio approach, the infrared and Raman rotational and vibrational-rotational spectral band contours for the water molecule are computed in the simplest rigid rotor, normal mode approximation. Quantum techniques are used to calculate the necessary potential energy, dipole moment, and polarizability information at the equilibrium geometry. A new quick, accurate, and easy to program classical technique involving no reference to Euler angles or special functions is developed to compute the infrared and Raman band contours for any rigid rotor, including asymmetric tops. A second, or simultaneous, type of ab initio approach is suggested for large systems, particularly those for which normal mode analysis is inappropriate, such as liquids, clusters, or floppy molecules. Then the curse of dimensionality prevents mapping out in advance the complete potential, dipole moment, and polarizability functions over the whole space of nuclear positions of all atoms, and a solution in which the electronic and nuclear parts of the Born-Oppenheimer approximation are simultaneously solved is needed. A quantum force classical trajectory (QFCT) molecular dynamic method, based on linear response theory, is described, in which the forces, dipole moment, and polarizability are computed quantum

  9. Microwave Spectra of Furazan. III. Rotation Spectra of Vibrationally Excited States

    NASA Astrophysics Data System (ADS)

    Stiefvater, Otto L.

    1990-10-01

    The pure rotational spectra of molecules in 21 vibrationally excited states of the heterocyclic compound furazan (C2H2N2O) have been detected and studied by DRM microwave spectroscopy. Rotational parameters are reported for the 12 fundamental levels below 1500 cm-1 , and the contri-butions from 10 vibrational modes to the effective rotational constants and to the inertia defect of furazan are calculated.

  10. 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.

  11. Simulation of dielectric spectra of erythrocytes with various shapes

    NASA Astrophysics Data System (ADS)

    Asami, Koji

    2009-07-01

    Dielectric spectra of erythrocyte suspensions were numerically simulated over a frequency range from 1 kHz to 100 MHz to study the effects of erythrocyte shape on the dielectric spectra. First, a biconcave-discoid model for normal erythrocytes or discocytes was compared with an equivalent oblate spheroid model. The two models showed similar dielectric spectra to each other, suggesting that the oblate spheroid model can be approximately used for discocytes. Second, dielectric spectra were simulated for discocytes deformed by osmotic cell swelling. The deformation resulted in the increase in relaxation intensity and the sharpening of spectrum shape. Finally, dielectric spectra were simulated for echinocytes, stomatocytes and sickle cells that are induced by chemical agents and diseases. The dielectric spectra of echinocytes and stomatocytes were similar to each other, being distinguishable from that of discocytes and quite different from that of sickle cells.

  12. Radial Distribution of Electron Spectra from High-Energy Ions

    NASA Technical Reports Server (NTRS)

    Cucinotta, Francis A.; Katz, Robert; Wilson, John W.

    1998-01-01

    The average track model describes the response of physical and biological systems using radial dose distribution as the key physical descriptor. We report on an extension of this model to describe the average distribution of electron spectra as a function of radial distance from an ion. We present calculations of these spectra for ions of identical linear energy transfer (LET), but dissimilar charge and velocity to evaluate the differences in electron spectra from these ions. To illustrate the usefulness of the radial electron spectra for describing effects that are not described by electron dose, we consider the evaluation of the indirect events in microdosimetric distributions for ions. We show that folding our average electron spectra model with experimentally determined frequency distributions for photons or electrons provides a good representation of radial event spectra from high-energy ions in 0.5-2 micrometer sites.

  13. Atomic lines in infrared spectra for ultracool dwarfs

    NASA Astrophysics Data System (ADS)

    Lyubchik, Y.; Jones, H. R. A.; Pavlenko, Y. V.; Viti, S.; Pickering, J. C.; Blackwell-Whitehead, R.

    2004-03-01

    We provide a set of atomic lines which are suitable for the description of ultracool dwarf spectra from 10 000 to 25 000 Å. This atomic linelist was made using both synthetic spectra calculations and existing atlases of infrared spectra of Arcturus and Sunspot umbra. We present plots which show the comparison of synthetic spectra and observed Arcturus and Sunspot umbral spectra for all atomic lines likely to be observable in high resolution infrared spectra. Figure 1 is only available in electronic form at http://www.edpsciences.org Tables 1 and 2 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/416/655

  14. Electrical Analogues of Optical & EELS Spectra: Silicon

    NASA Astrophysics Data System (ADS)

    Smith, David Y.; Karstens, William

    2014-03-01

    We have explored an analogy between optical and electrical-circuit resonances that yields insight into single-particle and collective excitations. The analogy rests on the similarity of the differential equations for the Drude-Lorentz model of optics and the impedance of ac circuits. A parallel combination of capacitive (C) and inductive-capacitive (L-C) branches is a suitable circuit model. The L-C branches correspond to single-particle excitations. The C branch accounts for the electric-field term in the displacement, or equivalently the free-space susceptibility. Collective excitations represent combination resonances of the L-C and C branches. These excitations involve only internal mesh currents that can flow in the absence of an external (input) current. In this case, the admittance of the circuit is zero corresponding to the vanishing of the dielectric function at the plasmon resonance in optics (absent resistive losses). Circuit impedance corresponds to charged-particle energy loss. In contrast, circuit admittance (inverse impedance) corresponds to optical measurements. The interference of mesh currents in the circuit model plays the role of Coulomb screening in energy-loss spectra. Supported in part by the US Department of Energy, Office of Nuclear Physics under contract DE-AC02-06CH11357.

  15. Absorption spectra of irradiated XRCT radiochromic film

    NASA Astrophysics Data System (ADS)

    Butson, Martin J.; Cheung, Tsang; Yu, Peter K. N.

    2006-06-01

    Gafchromic XRCT radiochromic film is a self-developing high sensitivity radiochromic film product which can be used for assessment of delivered radiation doses which could match applications such as computed tomography (CT) dosimetry. The film automatically changes colour upon irradiation changing from a yellow to green/brown colour. The absorption spectra of Gafchromic XRCT radiochromic film as measured with reflectance spectrophotometry have been investigated to analyse the dosimetry characteristics of the film. Results show two main absorption peaks produced from irradiation located at 636 nm and 585 nm. This is similar to EBT Gafchromic film. A high level of sensitivity is found for this film with a 1 cGy applied dose producing an approximate net optical density change of 0.3 at 636 nm. This high sensitivity combined with its relatively energy independent nature around the 100 kVp to 150 kVp x-ray energy range provides a unique enhancement in dosimetric measurement capabilities over currently available dosimetry films for CT applications.

  16. Estimating Shock Spectra: Extensions beyond GEVS

    NASA Technical Reports Server (NTRS)

    Igusa, Takeru; Maahs, Gordon L.

    2008-01-01

    Shock response spectra (SRS) are the standard description of some vibration environments on spacecraft for equipment qualification. For shock events produced by pyrotechnic devices, SRS can have significant frequency content as high as 10 kHz. It is difficult to construct and analyze finite element models that can resolve dynamic behavior at such high frequencies. GEVS provides simple, empirically based methods for approximating the SRS for a wide variety of shock events. It begins with a base SRS according to the type of pyrotechnic device, and then provides attenuation relations to adjust this SRS according to distance from the shock source, the type of structural frame and the properties of any structural joints between the source and equipment. In our paper we extend GEVS to include more detailed information about the spacecraft structure. To retain the general framework of GEVS, we begin with a base SRS and adjust this SRS using attenuation relations. We use modal and traveling wave concepts to derive the attenuation relations for simple canonical structures. Then we show how these concepts can be used to analyze more complex structures using finite element mode shapes to explicitly calculate the attenuation factors. Since the low- to mid-frequency finite element modal information is extrapolated to obtain the low- to high-frequency attenuation relations, the resulting attenuated SRS is formulated as an upper bound rather than as mean predicted values. We illustrate the extended GEVS approach by analyzing the impact response of composite tubes and the shock response of the STEREO spacecraft.

  17. Determination of phytoplankton composition using absorption spectra.

    PubMed

    Martínez-Guijarro, R; Romero, I; Pachés, M; Del Río, J G; Martí, C M; Gil, G; Ferrer-Riquelme, A; Ferrer, J

    2009-05-15

    Characterisation of phytoplankton communities in aquatic ecosystems is a costly task in terms of time, material and human resources. The general objective of this paper is not to replace microscopic counts but to complement them, by fine-tuning a technique using absorption spectra measurements that reduces the above-mentioned costs. Therefore, the objective proposed in this paper is to assess the possibility of achieving a qualitative determination of phytoplankton communities by classes, and also a quantitative estimation of the number of phytoplankton cells within each of these classes, using spectrophotometric determination. Samples were taken in three areas of the Spanish Mediterranean coast. These areas correspond to estuary systems that are influenced by both continental waters and Mediterranean Sea waters. 139 Samples were taken in 7-8 stations per area, at different depths in each station. In each sample, the absorption spectrum and the phytoplankton classes (Bacyllariophyceae (diatoms), Cryptophyceae, Clorophyceae, Chrysophyceae, Prasynophyceae, Prymnesophyceae, Euglenophyceae, Cyanophyceae, Dynophyceae and the Synechococcus sp.) were determined. Data were analysed by means of the Partial Least Squares (PLS) multivariate statistical technique. The absorbances obtained between 400 and 750 nm were used as the independent variable and the cell/l of each phytoplankton class was used as the dependent variable, thereby obtaining models which relate the absorbance of the sample extract to the phytoplankton present in it. Good results were obtained for diatoms (Bacillarophyceae), Chlorophyceae and Cryptophyceae. PMID:19269434

  18. A digital boxcar integrator for IMS spectra

    NASA Technical Reports Server (NTRS)

    Cohen, Martin J.; Stimac, Robert M.; Wernlund, Roger F.; Parker, Donald C.

    1995-01-01

    When trying to detect or quantify a signal at or near the limit of detectability, it is invariably embeded in the noise. This statement is true for nearly all detectors of any physical phenomena and the limit of detectability, hopefully, occurs at very low signal-to-noise levels. This is particularly true of IMS (Ion Mobility Spectrometers) spectra due to the low vapor pressure of several chemical compounds of great interest and the small currents associated with the ionic detection process. Gated Integrators and Boxcar Integrators or Averagers are designed to recover fast, repetitive analog signals. In a typical application, a time 'Gate' or 'Window' is generated, characterized by a set delay from a trigger or gate pulse and a certain width. A Gated Integrator amplifies and integrates the signal that is present during the time the gate is open, ignoring noise and interference that may be present at other times. Boxcar Integration refers to the practice of averaging the output of the Gated Integrator over many sweeps of the detector. Since any signal present during the gate will add linearly, while noise will add in a 'random walk' fashion as the square root of the number of sweeps, averaging N sweeps will improve the 'Signal-to-Noise Ratio' by a factor of the square root of N.

  19. AIS spectra of desert shrub canopies

    NASA Technical Reports Server (NTRS)

    Murray, R.; Isaacson, D. L.; Schrumpf, B. J.; Ripple, W. J.; Lewis, A. J.

    1986-01-01

    Airborne Imaging Spectrometer (AIS) data were collected 30 August 1985 from a desert shrub community in central Oregon. Spectra from artificial targets placed on the test site and from bare soil, big sagebrush (Artemesia tridentata wyomingensis), silver sagebrush (Artemesia cana bolander), and exposed volcanic rocks were studied. Spectral data from grating position 3 (tree mode) were selected from 25 ground positions for analysis by Principal Factor Analysis (PFA). In this grating position, as many as six factors were identified as significant in contributing to spectral structure. Channels 74 through 84 (tree mode) best characterized between-class differences. Other channels were identified as nondiscriminating and as associated with such errors as excessive atmospheric absorption and grating positin changes. The test site was relatively simple with the two species (A. tridentata and A. cana) representing nearly 95% of biomass and with only two mineral backgrounds, a montmorillonitic soil and volcanic rocks. If, as in this study, six factors of spectral structure can be extracted from a single grating position from data acquired over a simple vegetation community, then AIS data must be considered rich in information-gathering potential.

  20. Research on fluorescence spectra of cancer blood

    NASA Astrophysics Data System (ADS)

    Liu, Kunxiang; He, Wenliang; Zhao, Wenyan; Liu, Ying

    2007-11-01

    The fluorescence spectral characteristic of tumor blood was studied by laser-induced fluorescence technology, and compared with the fluorescence spectra of the same type healthy mice blood, the differences between them are distinct. When the whole blood solutions were induced by 407nm laser, they radiate fluorescence band from 420nm to 750 nm, which spectral peak located at 620nm. In high concentration solutions (blood concentration is higher than 4%), the fluorescence intensity are lower than normal blood, but in those low concentration solutions (blood concentration is lower than 2%) the fluorescence intensity of the tumor blood are higher than the normal ones. It is analyzed that the change of the fluorescence characteristic between the tumor blood and the normal is caused by the concentration difference of the tumor identification-porphyrin. The experimental results showed that the obvious difference of the fluorescence spectral characteristic between the forepart tumor and normal blood can offer some value assistance to clinical diagnosis on cancer.

  1. Optical spectra of high temperature superconductors

    SciTech Connect

    Ruvalds, J.

    1996-12-31

    The concept of free electrons which yields the Drude description of the conductivity works surprisingly well in conventional metals. By contrast, the infrared reflectivity of the cuprate superconductors deviates dramatically from Drude behavior and thus challenges theory to explain the origin of the anomalous electron damping and the related mass divergence which has implications for the existence of a Fermi surface. The controversial key issue of the carrier concentration in cuprates needs to be resolved by a conserving analysis of the puzzling conductivity. Raman spectra of cuprates also exhibit unconventional electronic contributions over a wide frequency range up to 1 eV, and recent data provide evidence for the symmetry of the superconducting energy gap. A microscopic theory for both the optical conductivity and the Raman anomalies in cuprates derives a linear frequency variation of the damping from electron-electron collisions on a nested Fermi surface that refers to nearly parallel segments of an electron trajectory. Thus the nesting theory links the cuprate anomalies to phenomena in chromium and rare earth metals. Nesting also yields a novel mechanism for d-wave superconductivity that requires a Coulomb repulsion of intermediate strength and key nesting features that distinguish high {Tc} cuprates from other materials. 41 refs., 7 figs.

  2. Supersymmetric standard model spectra from RCFT orientifolds

    NASA Astrophysics Data System (ADS)

    Dijkstra, T. P. T.; Huiszoon, L. R.; Schellekens, A. N.

    2005-03-01

    We present supersymmetric, tadpole-free d=4,N=1 orientifold vacua with a three family chiral fermion spectrum that is identical to that of the standard model. Starting with all simple current orientifolds of all Gepner models we perform a systematic search for such spectra. We consider several variations of the standard four-stack intersecting brane realization of the standard model, with all quarks and leptons realized as bifundamentals and perturbatively exact baryon and lepton number symmetries, and with a U(1 vector boson that does not acquire a mass from Green-Schwarz terms. The number of supersymmetric Higgs pairs H+H is left free. In order to cancel all tadpoles, we allow a "hidden" gauge group, which must be chirally decoupled from the standard model. We also allow for non-chiral mirror-pairs of quarks and leptons, non-chiral exotics and (possibly chiral) hidden, standard model singlet matter, as well as a massless B-L vector boson. All of these less desirable features are absent in some cases, although not simultaneously. In particular, we found cases with massless Chan-Paton gauge bosons generating nothing more than SU(3)×SU(2)×U(1). We obtain almost 180 000 rationally distinct solutions (not counting hidden sector degrees of freedom), and present distributions of various quantities. We analyse the tree level gauge couplings, and find a large range of values, remarkably centered around the unification point.

  3. Extracting Quantitative Data from Lunar Soil Spectra

    NASA Technical Reports Server (NTRS)

    Noble, S. K.; Pieters, C. M.; Hiroi, T.

    2005-01-01

    Using the modified Gaussian model (MGM) developed by Sunshine et al. [1] we compared the spectral properties of the Lunar Soil Characterization Consortium (LSCC) suite of lunar soils [2,3] with their petrologic and chemical compositions to obtain quantitative data. Our initial work on Apollo 17 soils [4] suggested that useful compositional data could be elicited from high quality soil spectra. We are now able to expand upon those results with the full suite of LSCC soils that allows us to explore a much wider range of compositions and maturity states. The model is shown to be sensitive to pyroxene abundance and can evaluate the relative portion of high-Ca and low-Ca pyroxenes in the soils. In addition, the dataset has provided unexpected insights into the nature and causes of absorption bands in lunar soils. For example, it was found that two distinct absorption bands are required in the 1.2 m region of the spectrum. Neither of these bands can be attributed to plagioclase or agglutinates, but both appear to be largely due to pyroxene.

  4. Polarized Matrix Infrared Spectra of Cyclopentadienone

    NASA Astrophysics Data System (ADS)

    Ormond, Thomas K.; Scheer, Adam M.; Ellison, G. Barney; Nimlos, Mark R.; Daily, John W.; Stanton, John F.

    2012-06-01

    We are developing a resistively-heated SiC μtubular reactor with a 100 μsec residence time to study the thermal cracking of biomass monomers. The decomposition products are identified by two independent techniques: 118.2 nm VUV photoionization mass spectrometry (PIMS) and matrix infrared spectroscopy. Many lignins thermally crack to produce cyclopentadienone (m/z 80) and its derivatives. Subsequent decomposition of these cyclopentadienones results in formation of substituted acetylenes which are known precursors to polycyclic aromatic hydrocarbons and soot. Due to its anitaromatic character, cyclopentadienone is highly reactive and presents an interesting spectroscopic system. Pyrolysis of {o}-phenylene sulfite (m/z 156) is a convenient precursor for cyclopentadienone. In this work we report the polarized matrix infrared absorption spectra of cyclopentadienone and d_4-cyclopentadienone. The PIMS results corroborate the thermal decomposition steps of phenylene sulfite. {Ab initio} coupled-cluster anharmonic force field calculations are used to guide the vibrational assignments. A. M. Scheer, C. Murkarakate, D. J. Robichaud, M. R. Nimlos, and G. B. Ellison J. Phys. Chem. A 115, 13381 (2011)

  5. The ultraviolet spectra of nearby radio galaxies

    NASA Technical Reports Server (NTRS)

    Keel, William C.; Windhorst, Rogier A.

    1991-01-01

    New and archival IUE SWP spectra are reported for nine nearby radio galaxies (V is less than 15 mag), together with optical emissionlike data for these galaxies as well as a number of candidates with weaker line emission. Both their UV line and continuum properties, as well as their UV and UV-optical line ratios, are examined. Ly-alpha emission is found to be common among local radio galaxies, at modest luminosities (typically 10 exp 41-42 erg/s). No apparent relation is found between L(Ly-alpha) and radio power for the nearby radio galaxies alone. The Ly-alpha/H-alpha ratio in low power nearby radio galaxies is 2-5 times lower than the prediction for case B recombination. The destruction of Ly-alpha photons by grains during resonant scattering can explain the observed deficiency for reasonable metallicities. The nearby radio galaxies have in general a small C IV/Ly-alpha ratio (less than 0.1). Comparison of the C IV and Ly-alpha strengths with those in luminous AGN suggests that most of the UV continuum comes from the stellar population, and not from the AGN.

  6. Complex permeability spectra of permendur composite materials

    NASA Astrophysics Data System (ADS)

    Kasagi, Teruhiro; Tsutaoka, Takanori; Hatakeyama, Kenichi

    2010-01-01

    Complex permeability μ* and permittivity epsilon* spectra of permendur (Co50Fe50) composite materials have been studied in the microwave frequency range considering the application to the left-handed meta-materials and EMC devices. High surface electrical resistance of the permendur particles was achieved by the heat-treatment in order to suppress the eddy current effect in the high particle content composites. For the 82.6 vol.% composite, the μ' is 11 and less than 1 at 100 MHz and 6 GHz, respectively; the μ'' shows the two peaks around 700 MHz and 3GHz due to the domain wall and gyromagnetic spin resonance. On the other hand, the epsilon' is almost constant value of 28 and the epsilon'' is almost zero in the frequency range from 100 MHz to 6 GHz. The calculated reflection loss of a single-layer electromagnetic wave absorber (EM absorber) designed by using permendur composites indicates less than -20 dB around the matching frequency of 1 GHz.

  7. Analysis of hyperfine structure in photoassociation spectra

    NASA Astrophysics Data System (ADS)

    Bergeman, T.

    2008-05-01

    The low Doppler width in photoassociation spectra from cold atoms makes hyperfine structure clearly visible, especially with heavier alkali atoms. Recently the focus has been on photoassociation to weakly bound dimers [1,2]. However there are also useful data on somewhat more deeply bound levels [2] for which a different coupling scheme is appropriate. Following [3], we use a F = J + I representation, and develop a transformation between this and the usual case e representation which applies at asymptotically large internuclear distance. We hope to model and assign hyperfine structure in φ = 1 states, using appropriate ground and excited state wavefunctions. To obtain eigenvalues from very large DVR matrices, we use a ``stepwise diagonalization'' procedure, which appears to be more efficient than standard sparse matrix methods. [1] E. Tiesinga et al. PRA 71, 052703 (2005); K. M. Jones et al, RMP 78, 483 (2006). [2] Data on Rb2 from J. Qi, D. Wang, Y. Huang, H. Pechkis, E. Eyler, P. Gould, W. C. Stwalley, C. C. Tsai and D.J. Heinzen; Data on RbCs from A. J. Kerman, J. M. Sage, S. Sainis and D. DeMille. [3] B. Gao, PRA 54, 2022 (1996).

  8. The Theory of Exoplanet Atmospheres and Spectra

    NASA Astrophysics Data System (ADS)

    Burrows, Adam S.

    2008-09-01

    Approximately 300 exoplanets, mostly giant planets (EGPs) in the Jovian mass range, have been detected orbiting stars in the solar neighborhood. More than 15% of them are transiting their primaries and these have collectively yielded a wealth of structural and physical information which theorists are scrambling to interpret. In this talk. I will present the current theory of the their atmospheres, compositions, and spectra. Due to stellar irradiation effects and heat redistribution by super-rotational jet streams, we must eventually construct with some fidelity 3D general circulation models (GCMs), with multi-D radiative transfer. However, simpler planar models with average irradiation boundary conditions and crude day-night heat transport algorithms do a reasonable 1st-order job of reproducing what is observed directly by the Spitzer infrared space telescope. In particular, thermal inversions and stratospheres are inferred for many close-in EGPs. I will discuss the confrontation of theory with data and summarize what has been learned to date.

  9. Spectra as windows into exoplanet atmospheres

    PubMed Central

    Burrows, Adam S.

    2014-01-01

    Understanding a planet’s atmosphere is a necessary condition for understanding not only the planet itself, but also its formation, structure, evolution, and habitability. This requirement puts a premium on obtaining spectra and developing credible interpretative tools with which to retrieve vital planetary information. However, for exoplanets, these twin goals are far from being realized. In this paper, I provide a personal perspective on exoplanet theory and remote sensing via photometry and low-resolution spectroscopy. Although not a review in any sense, this paper highlights the limitations in our knowledge of compositions, thermal profiles, and the effects of stellar irradiation, focusing on, but not restricted to, transiting giant planets. I suggest that the true function of the recent past of exoplanet atmospheric research has been not to constrain planet properties for all time, but to train a new generation of scientists who, by rapid trial and error, are fast establishing a solid future foundation for a robust science of exoplanets. PMID:24613929

  10. Xgremlin: Interferograms and spectra from Fourier transform spectrometers analysis

    NASA Astrophysics Data System (ADS)

    Nave, G.; Griesmann, U.; Brault, J. W.; Abrams, M. C.

    2015-11-01

    Xgremlin is a hardware and operating system independent version of the data analysis program Gremlin used for Fourier transform spectrometry. Xgremlin runs on PCs and workstations that use the X11 window system, including cygwin in Windows. It is used to Fourier transform interferograms, plot spectra, perform phase corrections, perform intensity and wavenumber calibration, and find and fit spectral lines. It can also be used to construct synthetic spectra, subtract continua, compare several different spectra, and eliminate ringing around lines.

  11. 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.

  12. Simulation and fitting of high resolution Rutherford backscattering spectra

    NASA Astrophysics Data System (ADS)

    Borschel, Christian; Schnell, Martin; Ronning, Carsten; Hofsäss, Hans

    2009-05-01

    A computer program for the analysis of high resolution Rutherford backscattering spectra (HR-RBS), which can be recorded with an electrostatic energy analyzer (ESA) and a resolution of about 1 keV, has been developed. The use of an ESA results in various differences compared to conventional RBS spectra, motivating the development of a new algorithm for simulation for these spectra. We present a Monte Carlo based diffusion-like fit approach for evaluation of the HR-RBS spectra, which is in particular useful for fitting concentration gradients. Examples for the application of the algorithm are shown to demonstrate its functionality.

  13. Neutron Spectra and H*(10) in a 15 MV Linac

    SciTech Connect

    Benites, J.; Vega-Carrillo, H. R.; Hernandez-Davila, V. M.; Rivera, T.; Carrillo, A.; Mondragon, R.

    2010-12-07

    Neutron spectra and the ambient dose equivalent were calculated inside the bunker of a 15 MV Varian linac model CLINAC iX. Calculations were carried out using Monte Carlo methods. Neutron spectra in the vicinity of isocentre show the presence of evaporation and knock-on neutrons produced by the source term, while epithermal and thermal neutron remain constant regardless the distance respect to isocentre, due to room return. Along the maze neutron spectra becomes softer as the detector moves along the maze. The ambient dose equivalent is decreased but do not follow the 1/r{sup 2} rule due to changes in the neutron spectra.

  14. Spectra of Optical Functions and Transitions in Diamond

    NASA Astrophysics Data System (ADS)

    Sobolev, V. V.; Timonov, A. P.; Sobolev, V. Val.

    2000-02-01

    Spectra of a complete set of optical functions are obtained for three different diamond samples in the region from 0 to 32 eV. The calculations were performed by the Kramers-Kronig method using experimental reflection spectra. Special features and differences of the spectra of optical functions of the three samples are analyzed. Based on the method of joined Argand diagrams, the spectra of the dielectric constant are decomposed into elementary components for the first time, and their energies and oscillator strengths are determined. The component structure is in good agreement with the theoretical spectrum of the dielectric constant and the expected spectrum of the interband transitions.

  15. Infrared spectra of lunar soil analogs. [spectral reflectance of minerals

    NASA Technical Reports Server (NTRS)

    Aronson, J. R.

    1977-01-01

    The infrared spectra of analogs of lunar soils were investigated to further the development of methodology for interpretation of remotely measured infrared spectra of the lunar surface. The optical constants of dunite, bytownite, augite, ilmenite, and a mare glass analog were obtained. The infrared emittance spectra of powdered minerals were measured and compared with spectra calculated by the reflectance theory using a catalog of optical constants. The results indicate that the predictions of the theory closely simulate the experimental measurements if the optical constants are properly derived.

  16. Prompt Fission Neutron Spectra of Actinides

    SciTech Connect

    Capote, R; Chen, Y J; Hambsch, F J; Kornilov, N V; Lestone, J P; Litaize, O; Morillon, B; Neudecker, D; Oberstedt, S; Ohsawa, T; Smith, D. L.

    2016-01-01

    The energy spectrum of prompt neutrons emitted in fission (PFNS) plays a very important role in nuclear science and technology. A Coordinated Research Project (CRP) “Evaluation of Prompt Fission Neutron Spectra of Actinides”was established by the IAEA Nuclear Data Section in 2009, with the major goal to produce new PFNS evaluations with uncertainties for actinide nuclei. The following technical areas were addressed: (i) experiments and uncertainty quantification (UQ): New data for neutron-induced fission of 233U, 235U, 238U, and 239Pu have been measured, and older data have been compiled and reassessed. There is evidence from the experimental work of this CRP that a very small percentage of neutrons emitted in fission are actually scission neutrons; (ii) modeling: The Los Alamos model (LAM) continues to be the workhorse for PFNS evaluations. Monte Carlo models have been developed that describe the fission phenomena microscopically, but further development is needed to produce PFNS evaluations meeting the uncertainty targets; (iii) evaluation methodologies: PFNS evaluations rely on the use of the least-squares techniques for merging experimental and model data. Considerable insight was achieved on how to deal with the problem of too small uncertainties in PFNS evaluations. The importance of considering that all experimental PFNS data are “shape” data was stressed; (iv) PFNS evaluations: New evaluations, including covariance data, were generated for major actinides including 1) non-model GMA evaluations of the 235U(nth,f), 239Pu(nth,f), and 233U(nth,f) PFNS based exclusively on experimental data (0.02 ≤ E ≤ 10 MeV), which resulted in PFNS average energies E of 2.00±0.01, 2.073±0.010, and 2.030±0.013 MeV, respectively; 2) LAM evaluations of neutron-induced fission spectra on uranium and plutonium targets with improved UQ for incident energies from thermal up to 30 MeV; and 3) Point-by-Point calculations for 232Th, 234U and 237Np targets; and (v) data

  17. Mutation spectra of complex environmental mixtures

    SciTech Connect

    DeMarini, D.M.

    1997-10-01

    Bioassay-directed chemical analysis of complex environmental mixtures has indicated that much of the genotoxic activity of mixtures is due to the presence of one or a few classes or chemicals within the mixture. We have extended this observation to the molecular level by using colony probe hybridization and PCR/DNA sequence analysis to determine the mutation spectra of {approximately}8,000 revertants induced by a variety of complex mixtures and their chemical fractions in TA100 and TA98 of Salmonella. For urban air, >80% of mutagenic activity was due to a base/neutral fraction that contained primarily PAHs. The mutation spectrum induced by unfractionated urban air was not significantly different from that produced by a model PAH, B(a)P. The mutation spectrum induced by organic extracts of chlorinated drinking water were similar to those produced by the chlorinated furanone MX, which accounted for {approximately}20% of the mutagenic activity of the samples. The base/neutral fraction of municipal waste incinerator emissions accounted for the primary class of mutations induced by the emissions, and a polar neutral fraction accounted for the secondary class of mutations induced by the emissions. The primary class of mutations induced by cigarette smoke condensate in TA100 (GC {yields} TA) is also the primary class of mutations in the p53 gene of lung tumors of cigarette smokers. These results confirm at the molecular level that the mutations induced by a complex mixture reflect the dominance of one or a few classes of chemicals within the mixture.

  18. Quantum confinement in metal nanofilms: Optical spectra

    NASA Astrophysics Data System (ADS)

    Khmelinskii, Igor; Makarov, Vladimir I.

    2016-05-01

    We report optical absorption and photoluminescence spectra of Au, Fe, Co and Ni polycrystalline nanofilms in the UV-vis-NIR range, featuring discrete bands resulting from transverse quantum confinement. The film thickness ranged from 1.1 to 15.6 nm, depending on the material. The films were deposited on fused silica substrates by sputtering/thermo-evaporation, with Fe, Co and Ni protected by a SiO2 film deposited on top. The results are interpreted within the particle-in-a-box model, with the box width equal to the mass thickness of the nanofilm. The transverse-quantized energy levels and transition energies scale as the inverse square of the film thickness. The calculated values of the effective electron mass are 0.93 (Au), 0.027 (Fe), 0.21 (Co) and 0.16 (Ni), in units of mo - the mass of the free electron, being independent on the film thickness. The uncertainties in the effective mass values are ca. 2.5%, determined by the film thickness calibration. The second calculated model parameter, the quantum number n of the HOMO, was thickness-independent in Au (5.00) and Fe (6.00), and increased with the film thickness in Co (from 7 to 9) and Ni (from 7 to 11). The transitions observed in the absorbance all start at the level n and correspond to Δn=+1, +2, +3, etc. The photoluminescence bands exhibit large Stokes shifts, shifting to higher energies with the increased excitation energy. The photoluminescence quantum yields grow linearly with the excitation energy, showing evidence of multiple exciton generation. A prototype Fe-SnO2 nanofilm photovoltaic cell demonstrated at least 90% quantum yield of photoelectrons at 77 K.

  19. HOT ELECTROMAGNETIC OUTFLOWS. I. ACCELERATION AND SPECTRA

    SciTech Connect

    Russo, Matthew; Thompson, Christopher

    2013-04-20

    The theory of cold, relativistic, magnetohydrodynamic outflows is generalized by the inclusion of an intense radiation source. In some contexts, such as the breakout of a gamma-ray burst (GRB) jet from a star, the outflow is heated to a high temperature at a large optical depth. Eventually it becomes transparent and is pushed to a higher Lorentz factor by a combination of the Lorentz force and radiation pressure. We obtain its profile, both inside and outside the fast magnetosonic critical point, when the poloidal magnetic field is radial and monopolar. Most of the energy flux is carried by the radiation field and the toroidal magnetic field that is wound up close to the rapidly rotating engine. Although the entrained matter carries little energy, it couples the radiation field to the magnetic field. Then the fast critical point is pulled inward from infinity and, above a critical radiation intensity, the outflow is accelerated mainly by radiation pressure. We identify a distinct observational signature of this hybrid outflow: a hardening of the radiation spectrum above the peak of the seed photon distribution, driven by bulk Compton scattering. The non-thermal spectrum-obtained by a Monte Carlo method-is most extended when the Lorentz force dominates the acceleration, and the seed photon beam is wider than the Lorentz cone of the MHD fluid. This effect is a generic feature of hot, magnetized outflows interacting with slower relativistic material. It may explain why some GRB spectra appear to peak at photon energies above the original Amati et al. scaling. A companion paper addresses the case of jet breakout, where diverging magnetic flux surfaces yield strong MHD acceleration over a wider range of Lorentz factor.

  20. Statistical Analysis of Spectra with Many Lines

    NASA Astrophysics Data System (ADS)

    van Dyk, D. A.; Kang, H. S.; Connors, A.; Kashyap, V. L.; Siemiginowska, A.

    2001-12-01

    Please join us in our wider effort to engage the strengths of modern computational statistics methods in solving challenging stellar and solar data analysis problems. As just one example (of a great breadth of possibilities) consider analyzing a spectrum with a very large number of lines. Some of these may be faint, merged, indistinguishable from each other and the underlying smooth continuum. The ensemble of line intensities follows a predictable distribution. The shape of this distribution depends on the properties of the source, e.g., its temperature, abundances, and emission measure. Hence, a better understanding of the distribution of line fluxes in a particular source may tighten our inference for other model parameters such as temperature---even when very few lines are actually easy to distinguish. To take advantage of this structure, we directly model the distribution of the line fluxes rather than fitting each line flux directly or ``investing'' the emissivities to get a DEM. Statistically, this strategy reduces the number of free parameters, which we expect will lead to improved statistical properties. We believe this method holds much promise for improved analysis, especially for low count sources. For example, we expect this method to correctly account for the ``pseudo-continuum'' that results from the large number of faint, unresolvable lines in X-ray grating spectra. Moreover, our statistical methods should apply directly to other settings involving a multitude of lines such as timing data. We hope that these methods will increase our statistical power to set the continuum level in the presence of a multitude of lines and to distinguish weak lines from fluctuations in the continuum. Funding for this project partially provided by NSF grant and DMS-01-04129 and by NASA Contract NAS8-39073 (CXC).

  1. Measuring Transmission Spectra from the Ground

    NASA Astrophysics Data System (ADS)

    Jordan, Andres; Espinoza, Nestor; Eyheramendy, Susana

    2015-08-01

    Transmission spectroscopy allows study of the atmospheres of exoplanets without the need of spatially resolving them from their parent stars and is one of the most valuable follow-up possibilities offered by transiting systems. The measurement of a transmission spectrum, i.e. the apparent planetary size in units in the stellar radius as a function of wavelength, is conceptually simple, but the expected features that need to be discerned are on the order of one part in a thousand or less, and need to be extracted against a background of (potentially correlated) noise and systematic effects with amplitudes greatly exceeding that of the sought signal. In this talk I will describe how we have tackled the estimation of transmission spectra in a ground based survey we are carrying out with IMACS at Las Campanas Observatory, the Arizona-CfA-Catolica Exoplanet Spectroscopy Survey. Our treatment assumes an additive model consisting of the signal, common systematics and one of a set of stochastic processes with different memory characteristics for the noise. Common systematics are estimated from comparison stars using principal component analysis and the model parameter posterior distributions are estimated using MCMC. Model comparison is used to let the data select the model with the most appropriate noise component. I will illustrate the performance of our approach, and discuss possible avenues of improvement. I will also illustrate the importance of potential biases arising from our incomplete knowledge of stellar properties. In particular, I will show that limb darkening assumptions can limit the accuracy of our estimates of planetary radii above the achievable precisions in regimes currently being probed.

  2. Predicted vibrational spectra from anharmonic potential functions

    SciTech Connect

    Dunn, K.M.

    1986-01-01

    The dissertation develops a procedure for predicting vibrational spectra of polyatomic molecules from a combination of theoretical and experimental information. Ab initio quantum chemical calculations provide anharmonic force constants including cubics and diagonal quartics. A variational procedure analogous to configuration interaction is then used to compute eigenvalues of the pure vibrational Hamiltonian. The diagonal quadratic force constants are then adjusted until the calculated fundamental frequencies agree with experiment. The resulting theoretical-experimental force field may then be used to predict the energies of vibrationally excited states. The method is applied to three molecules: hydrogen cyanide, ammonia, and methyl fluoride. For hydrogen cyanide, the dissertation presents predicted energies for all of the vibrationally excited states with up to four quanta of excitation distributed among the four modes. The root-mean-square error is 8.7 cm{sup {minus}1} for the states below 11,000 cm{sup {minus}1}. The force constants for ammonia are adjusted to reproduce the fundamental frequencies of ND{sub 3}. The force constants then predict the energies of states below 7000 cm{sup {minus}1} with an rms error of 5.8 cm{sup {minus}1} for ND{sub 3} and 16.7 cm{sup {minus}1} for NH{sub 3}. Finally, the adjusted force constants for methyl fluoride predict the energies of states below 4100 cm{sup {minus}1} with an rms error of 4.3 cm{sup {minus}1}. These force constants are also used to predict the CH stretching overtone region of CH{sub 3}F and the first, second and third overtone regions of CD{sub 2}FH for which experimental information is not available.

  3. Infrared Extinction Spectra of Mineral Dust Aerosol

    NASA Astrophysics Data System (ADS)

    Kleiber, P.; Laskina, O.; Alexander, J. M.; Young, M.; Grassian, V. H.

    2012-12-01

    Mineral dust aerosol affects the atmosphere by absorbing and scattering radiation and plays an important role in the Earth's radiative budget. The effect of atmospheric dust on climate is studied by various remote sensing techniques that use measurements from narrow band IR channels of satellites to determine key atmospheric properties. Therefore, it is essential to take radiative effects of mineral dust aerosol into account to correctly process remote sensing data. As aerosols are transported through the atmosphere they undergo aging and heterogeneous chemistry. This leads to changes in their optical properties and their effects on climate. In this study we carried out spectral simulations using both Mie theory and solutions derived in the Rayleigh regime for authentic dust samples and several processed components of mineral dust. Simulations of the extinction based on Mie theory shows that it does not accurately reproduce the peak position and band shape of the prominent IR resonance features. Errors in the simulated peak position and the line shape associated with Mie theory can adversely affect determination of mineral composition based on IR satellite data. Analytic solutions for various shapes derived from Rayleigh theory offer a better fit to the major band features of the spectra, therefore the accuracy of modeling atmospheric dust properties can be improved by using these analytic solutions. It is also important to take aging of mineral dust into account. We investigated the effect of chemical processing on the optical properties. It was shown that interactions of components of mineral dust (calcite, quartz and kaolinite) with humic and organic acids cause a shift of the IR resonance bands of these minerals. It may indicate changes in shape of the particles as well as changes in hygroscopicity and, as the result, the water content in these samples. Therefore, care should be taken when modeling optical properties of aged mineral dust.

  4. First Infrared Spectra of Nitrous Oxide Pentamer

    NASA Astrophysics Data System (ADS)

    Rezaei, M.; Oliaee, J. Norooz; Moazzen-Ahmadi, N.; McKellar, A. R. W.

    2012-06-01

    High resolution spectra have previously been studied for N_2O dimers (two isomers), trimers (one isomer), and tetramers (two isomers). Here, we assign two new bands to the N_2O pentamer. The bands are observed in the region of the N_2O νb{1} fundamental using a tunable laser to probe a pulsed supersonic slit jet expansion. They are centered at 2233.9 and 2236.4 wn for 14N_2O, and at 2164.4 and 2166.8 wn for 15N_2O. Attribution to the pentamer is based on comparison of the observed rotational constants with theoretical ones from calculated cluster structures based on two rather different N_2O pair potentials. The first potential function is from a recent high level ab initio study. The second potential is a relatively simple empirical one, based partly on fitting to bulk properties. The likely pentamer structure is a completely unsymmetric one. It can be visualized starting with a highly symmetric oblate tetramer which is attacked by a fifth monomer, locating itself at a favorable distance and breaking the symmetry. Interestingly, analysis of the two bands yields very similar but not quite identical ground state parameters. We believe that they are due to distinct isomers having this same basic structure but differing in the orientation direction of one N_2O monomer. [1] R. Dawes, X.-G. Wang, A.W. Jasper, and T. Carrington, Jr., {J. Chem. Phys.} {133}, 134304 (2010). [2] B. Kutcha, R.D. Etters, and R. LeSar, {J. Chem. Phys.} {97}, 5662 (1992). [3] J.N. Oliaee, M. Dehghany, N. Moazzen-Ahmadi, and A.R.W. McKellar, {J. Chem. Phys.} {134}, 074310 (2011).

  5. 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.

  6. Hot Electromagnetic Outflows. I. Acceleration and Spectra

    NASA Astrophysics Data System (ADS)

    Russo, Matthew; Thompson, Christopher

    2013-04-01

    The theory of cold, relativistic, magnetohydrodynamic outflows is generalized by the inclusion of an intense radiation source. In some contexts, such as the breakout of a gamma-ray burst (GRB) jet from a star, the outflow is heated to a high temperature at a large optical depth. Eventually it becomes transparent and is pushed to a higher Lorentz factor by a combination of the Lorentz force and radiation pressure. We obtain its profile, both inside and outside the fast magnetosonic critical point, when the poloidal magnetic field is radial and monopolar. Most of the energy flux is carried by the radiation field and the toroidal magnetic field that is wound up close to the rapidly rotating engine. Although the entrained matter carries little energy, it couples the radiation field to the magnetic field. Then the fast critical point is pulled inward from infinity and, above a critical radiation intensity, the outflow is accelerated mainly by radiation pressure. We identify a distinct observational signature of this hybrid outflow: a hardening of the radiation spectrum above the peak of the seed photon distribution, driven by bulk Compton scattering. The non-thermal spectrum—obtained by a Monte Carlo method—is most extended when the Lorentz force dominates the acceleration, and the seed photon beam is wider than the Lorentz cone of the MHD fluid. This effect is a generic feature of hot, magnetized outflows interacting with slower relativistic material. It may explain why some GRB spectra appear to peak at photon energies above the original Amati et al. scaling. A companion paper addresses the case of jet breakout, where diverging magnetic flux surfaces yield strong MHD acceleration over a wider range of Lorentz factor.

  7. AGNs with composite spectra. II. Additional data

    NASA Astrophysics Data System (ADS)

    Gonçalves, A. C.; Véron-Cetty, M.-P.; Véron, P.

    1999-03-01

    In a previous paper \\cite[(Véron et al. 1997)]{ver97} we presented medium resolution (3.4 Angstroms FWHM) spectroscopic observations of 15 ``transition objects'', selected for having an ambiguous location in the \\cite[Veilleux & Osterbrock (1987)]{vei87} diagnostic diagrams, and showed that most of them were in fact ``composite'', this being due to the simultaneous presence on the slit of both a Seyfert or Liner nucleus and a H Ii region. Here, we report new spectroscopic observations of 53 emission-line galaxies with a ``transition'' spectrum, bringing up to 61 the total number of observed objects in an unbiased sample of 88 ``transition objects''. Almost all of the observed galaxies have a ``composite" nature, confirming the finding that true ``transition'' spectra may not exist at all. By eliminating ``composite objects'' from the diagnostic diagrams, a clear separation between the different classes of nuclear emission-line regions (Seyfert 2s, Liners and H Ii regions) becomes apparent; by restricting the volume occupied by the different line-emitting regions in the 3-dimensional diagnostic diagrams, we are also restricting the range of possible physical parameters in these regions. There seems to be no continuity between Seyfert 2s and Liners, the two classes occupying distinct volumes in the 3-dimensional space defined by lambda 6300/Hα ii, lambda 6583/Hα , and lambda 6300/Hα . Based on observations collected at the Observatoire de Haute-Provence (CNRS), France, and Hubble Space Telescope (HST) data obtained from the Space Telescope European Coordinating Facility (ST-ECF) archive. Tables 5 and 6 are also 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/Abstract.html

  8. 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.

  9. Electronic spectra of structurally deformed lutein.

    PubMed

    Macernis, Mindaugas; Sulskus, Juozas; Duffy, Christopher D P; Ruban, Alexander V; Valkunas, Leonas

    2012-10-11

    Quantum chemical calculations have been employed for the investigation of the lowest excited electronic states of lutein, with particular reference to its function within light harvesting antenna complexes of higher plants. Through comparative analysis obtained by using different methods based on gas-phase calculations of the spectra, it was determined that variations in the lengths of the long C-C valence bonds and the dihedral angles of the polyene chain are the dominant factors in determining the spectral properties of Lut 1 and Lut 2 corresponding to the deformed lutein molecules taken from crystallographic data of the major pigment-protein complex of photosystem II. By MNDO-CAS-CI method, it was determined that the two singlet B(u) states of lutein (nominally 1B(u)(-)* and 1B(u)(+)) arise as a result of mixing of the canonical 1B(u)(-) and 1B(u)(+) states of the all-trans polyene due to the presence of the ending rings in lutein. The 1B(u)(-)* state of lutein is optically allowed, while the 1B(u)(-) of a pure all-trans polyene chain is optically forbidden. As demonstrated, the B(u) states are much more sensitive to minor distortions of the conjugated chain due to mixing of the canonical states, resulting in states of poorly defined particle-hole symmetry. Conversely, the A(g) states are relatively robust with respect to geometric distortion, and their respective inversion and particle-hole symmetries remain relatively well-defined. PMID:22974387

  10. Comparison of IMP and orbital spectra

    NASA Astrophysics Data System (ADS)

    Herkenhoff, K. E.; Johnson, J. R.; Lemmon, M.; Reid, R.; Smith, P. H.

    2000-10-01

    Visible and near-infrared spectra from the Imager for Mars Pathfinder (IMP) camera have been used to characterize the color and infer the composition and physical nature of the Pathfinder landing site. The range of colors and albedos of materials at the Pathfinder landing site is similar to that observed in Viking Orbiter and HST images of Mars, but precise comparisons are hampered by the effects of atmospheric scattering in these data sets and differences in the effective wavelengths of the images. Such comparisons will allow the spectral units observed at the Pathfinder landing site to be placed into a global geologic context, and the composition, physical properties, and origins of Martian surface units to be inferred. We will report on our progress toward achieving these objectives by calibrating, modeling, and analyzing IMP multispectral observations of various surface materials and comparing them to the color and albedo units observed by the Viking Orbiter cameras, the WF/PC2 on HST, and the MOC wide-angle cameras on MGS. Improved spectral reflectance measurements of rock and soil units at the Pathfinder site are available for the Superpan and photometric equator datasets as a result of more precise IMP calibration algorithms and improved automated spatial registration and mosaicking tools developed in the USGS ISIS environment. A method for ingesting and processing WF/PC2 images into ISIS is being developed. Analyses of these data sets will help to determine the relative importance and timing of geologic processes that have affected the Pathfinder landing site, and therefore constrain the geologic history of the site. The relationships between various spectral units, as observed at the Pathfinder landing site, may be extrapolated to infer the stratigraphic relations between these units regionally and perhaps globally. This research is supported by the NASA Mars Data Analysis Program.

  11. Database-Driven Analyses of Astronomical Spectra

    NASA Astrophysics Data System (ADS)

    Cami, Jan

    2012-03-01

    species to the fullerene species C60 and C70 [4]. Given the large number and variety of molecules detected in space, molecular infrared spectroscopy can be used to study pretty much any astrophysical environment that is not too energetic to dissociate the molecules. At the lowest energies, it is interesting to note that molecules such as CN have been used to measure the temperature of the Cosmic Microwave Background (see e.g., Ref. 15). The great diagnostic potential of infrared molecular spectroscopy comes at a price though. Extracting the physical parameters from the observations requires expertise in knowing how various physical processes and instrumental characteristics play together in producing the observed spectra. In addition to the astronomical aspects, this often includes interpreting and understanding the limitations of laboratory data and quantum-chemical calculations; the study of the interaction of matter with radiation at microscopic scales (called radiative transfer, akin to ray tracing) and the effects of observing (e.g., smoothing and resampling) on the resulting spectra and possible instrumental effects (e.g., fringes). All this is not trivial. To make matters worse, observational spectra often contain many components, and might include spectral contributions stemming from very different physical conditions. Fully analyzing such observations is thus a time-consuming task that requires mastery of several techniques. And with ever-increasing rates of observational data acquisition, it seems clear that in the near future, some form of automation is required to handle the data stream. It is thus appealing to consider what part of such analyses could be done without too much human intervention. Two different aspects can be separated: the first step involves simply identifying the molecular species present in the observations. Once the molecular inventory is known, we can try to extract the physical parameters from the observed spectral properties. For both

  12. Delayed Neutron Energy Spectra Following Fast Fission of Uranium

    NASA Astrophysics Data System (ADS)

    Villani, Marcel Franklin

    Delayed neutron energy spectra have been measured for six delay-time intervals following the fast fission of ^{238}U nuclei. The delay-time intervals span the range 0.17 to 10.2 seconds following initial fission while the measured spectra span neutron energies from 10 keV to 4 MeV. The experiment was performed utilizing the UMass/Lowell 5.5 MV Van de Graaff accelerator to produce fast neutrons for inducing fission in a ^{238} U lined fission chamber. The fission fragments were flushed via a helium jet stream to a well-shielded counting room where they were deposited onto a moving tape (magnetic audio tape) and transferred to a beta-neutron time-of-flight spectrometer. By adjusting the tape speed, composite delayed neutron time-of-flight spectra were measured for several different delay-time intervals. These measurements involved beta-neutron coincidences with ^6 Li-loaded glass scintillators for neutron energies from 10 keV to 450 keV and Bicron BC 501 liquid scintillators for the neutron energy range 200 keV-4 MeV. The measured composite delayed neutron energy spectra for ^{238}U are compared to the composite spectra for ^ {235}U and ^{239} Pu, and also to composite spectra derived for ^{238}U from the ENDF/B-VI database, which is based on summation calculations of individual precursor data supplemented by theoretical estimates. The composite spectra of ^{235}U and ^{239}Pu were obtained from previous measurements of delayed neutron spectra at this laboratory. The composite spectra are also decomposed into Keepin six-group spectra and compared with those for ^{239}Pu and ^{235}U. In addition, an equilibrium spectrum has been calculated from the measured composite spectra using several different analytical techniques and is also compared with the equilibrium spectrum of ^{238}U measured in an earlier study at this laboratory.

  13. Automated evaluation of chemical shift perturbation spectra: New approaches to quantitative analysis of receptor-ligand interaction NMR spectra

    PubMed Central

    Peng, Chen; Unger, Stephen W.; Filipp, Fabian V.; Sattler, Michael; Szalma, Sándor

    2016-01-01

    This paper presents new methods designed for quantitative analysis of chemical shift perturbation NMR spectra. The methods automatically trace the displacements of cross peaks between a perturbed test spectrum and the reference spectrum (or among a series of titration spectra), and measure the changes of chemical shifts, heights, and widths of the altered peaks. The methods are primary aimed at the 1H-15N HSQC spectra of relatively small proteins (<15 kDa) assuming fast exchange between free and ligand-bound states on the chemical shift time scale, or for comparing spectra of free and fully bound states in the slow exchange situation. Using the 1H-15N HSQC spectra from a titration experiment of the 74-residue Pex13p SH3 domain with a Pex14p peptide ligand (14 residues, Kd = ~ 40µM), we demonstrate the scope and limits of our automatic peak tracing (APET) algorithm for efficient scoring of high-throughput SAR by NMR type HSQC spectra, and progressive peak tracing (PROPET) algorithm for detailed analysis of ligand titration spectra. Simulated spectra with low signal-to-noise ratios (S/N ranged from 20 to 1) were used to demonstrate the reliability and reproducibility of the results when dealing with poor quality spectra. These algorithms have been implemented in a new software module, FELIX-Autoscreen, for streamlined processing, analysis and visualization of SAR by NMR and other high-throughput receptor/ligand interaction experiments. PMID:15243180

  14. A comparative study of using in-line near-infrared spectra, ultraviolet spectra and fused spectra to monitor Panax notoginseng adsorption process.

    PubMed

    Jiang, Cheng; Qu, Haibin

    2015-01-01

    The step of enriching and purifying saponins by macroporous resin column chromatography is closely related to the safety and efficacy of Panax notoginseng products during their manufacturing processes. Adsorption process is one of the most critical unit operations within each chromatographic cycle. In order to understand the adsorption process directly, it is necessary to develop a rapid and precise method to monitor the adsorption process in real time. In this study, comparative evaluation of using near-infrared (NIR) spectra, ultraviolet (UV) spectra and fused spectra to monitor the adsorption process of P. notoginseng was conducted. The uninformative variable elimination by partial least squares (UVE-PLS) regression models were established for quantification of notoginsenoside R1, ginsenoside Rg1, ginsenoside Re, ginsenoside Rb1 and ginsenoside Rd in effluents based on different spectra. There was a significant improvement provided by the models based on fused spectra. The results in this work were conducive to solving the problems about real-time quantitative analysis of saponins during P. notoginseng adsorption. The fusion method of NIR and UV spectra combined with UVE-PLS regression could be a promising strategy to real-time analyze the components, which are difficult to be quantified by individual spectroscopic technique. PMID:25255448

  15. Impedance spectra of hot, dry silicate minerals and rocks: qualitative interpretation of spectra

    USGS Publications Warehouse

    Huebner, J.S.; Dillenburg, R.G.

    1995-01-01

    Impedance spectroscopy helps distinguish the contributions that grain interiors and grain boundaries make to electrical resistance of silicate minerals and rocks. Olivine, orthopyroxene, clinopyroxenes, and both natural and synthetic clinopyroxenite were measured. A network of electrical elements is presented for use in interpreting impedance spectra and conductive paths in hot or cold, wet or dry, minerals and rocks at any pressure. In dry rocks, a series network path predominates; in wet rocks, aqueous pore fluid and crystals both conduct. Finite resistance across the sample-electrode interface is evidence that electronic charge carriers are present at the surface, and presumably within, the silicate minerals and rocks measured. -from Authors

  16. The width of gamma-ray burst spectra

    NASA Astrophysics Data System (ADS)

    Axelsson, Magnus; Borgonovo, Luis

    2015-03-01

    The emission processes active in the highly relativistic jets of gamma-ray bursts (GRBs) remain unknown. In this paper, we propose a new measure to describe spectra: the width of the EFE spectrum, a quantity dependent only on finding a good fit to the data. We apply this to the full sample of GRBs observed by Fermi/Gamma-ray Burst Monitor (GBM) and Compton Gamma-ray Observatory/Burst and Transient Source Experiment (BATSE). The results from the two instruments are fully consistent. We find that the median widths of spectra from long and short GRBs are significantly different (chance probability <10-6). The width does not correlate with either duration or hardness, and this is thus a new, independent distinction between the two classes. Comparing the measured spectra with widths of spectra from fundamental emission processes - synchrotron and blackbody radiation - the results indicate that a large fraction of GRB spectra are too narrow to be explained by synchrotron radiation from a distribution of electron energies: for example, 78 per cent of long GRBs and 85 per cent of short GRBs are incompatible with the minimum width of standard slow cooling synchrotron emission from a Maxwellian distribution of electrons, with fast cooling spectra predicting even wider spectra. Photospheric emission can explain the spectra if mechanisms are invoked to give a spectrum much broader than a blackbody.

  17. X-Ray Absorption Spectra of Uranium by Synchrotron Radiation

    NASA Astrophysics Data System (ADS)

    Adachi, Hirohiko; Fujima, Kazumi; Taniguchi, Kazuo; Miyake, Chie; Imoto, Shosuke

    1981-08-01

    The X-ray absorption spectra of U, UO2 and UCl4 near the U OIV and OV thresholds have been measured by use of synchrotron radiation. The absorption peaks at about 100 eV and 110 eV are observed for all of these materials. However, the detailed structure of the spectra depend on the chemical state.

  18. Numerical analysis of EPR spectra. 7. The simplex algorithm

    NASA Astrophysics Data System (ADS)

    Beckwith, Athelstan L. J.; Brumby, Steven

    The Simplex algorithm is well suited to the least-squares analysis of highly complex EPR spectra. The application of the algorithm to the analysis of the spectra of benzo[ a]pyrenyl-6-oxy, chloro(methoxycarbonyl)methyl, and cyano(methoxy)methyl free radicals is described.

  19. Elemental composition and energy spectra of galactic cosmic rays

    NASA Technical Reports Server (NTRS)

    Mewaldt, R. A.

    1988-01-01

    A brief review is presented of the major features of the elemental composition and energy spectra of galactic cosmic rays. The requirements for phenomenological models of cosmic ray composition and energy spectra are discussed, and possible improvements to an existing model are suggested.

  20. Spent-fuel photon and neutron source spectra

    SciTech Connect

    Hermann, O.W.; Alexander, C.W.

    1983-01-01

    Computational activities at Oak Ridge National Laboratory have been performed to develop appropriate data and techniques for computing the photon and neutron source spectra of spent fuel. The methods reviewed here include both the determination of spent-fuel composition and the radiation source spectra associated with these isotopic inventories.

  1. An investigation of a mathematical model for atmospheric absorption spectra

    NASA Technical Reports Server (NTRS)

    Niple, E. R.

    1979-01-01

    A computer program that calculates absorption spectra for slant paths through the atmosphere is described. The program uses an efficient convolution technique (Romberg integration) to simulate instrument resolution effects. A brief information analysis is performed on a set of calculated spectra to illustrate how such techniques may be used to explore the quality of the information in a spectrum.

  2. Measuring x-ray spectra of flash radiographic sources

    SciTech Connect

    Gehring, Amanda Elizabeth; Espy, Michelle A.; Haines, Todd Joseph; Mendez, Jacob; Moir, David C.; Sedillo, Robert; Shurter, Roger P.; Volegov, Petr Lvovich; Webb, Timothy J

    2015-11-02

    The x-ray spectra of flash radiographic sources is difficult to measure. The sources measured were Radiographic Integrated Test Stand-6 (370 rad at 1 m; 50 ns pulse) and Dual Axis Radiographic Hydrodynamic Test Facility (DARHT) (550 rad at 1 m; 50 ns pulse). Features of the Compton spectrometer are described, and spectra are shown. Additional slides present data on instrumental calibration.

  3. ARES I-X USS Fracture Analysis Loads Spectra Development

    NASA Technical Reports Server (NTRS)

    Larsen, Curtis; Mackey, Alden

    2008-01-01

    This report describes the development of a set of bounding load spectra for the ARES I-X launch vehicle. These load spectra are used in the determination of the critical initial flaw size (CIFS) of the welds in the ARES I-X upper stage simulator (USS).

  4. Infrared spectra of interstellar deuteronated PAHs

    NASA Astrophysics Data System (ADS)

    Buragohain, Mridusmita; Pathak, Amit; Sarre, Peter

    2015-08-01

    Polycyclic Aromatic Hydrocarbon (PAH) molecules have emerged as a potential constituent of the ISM that emit strong features at 3.3, 6.2, 7.7, 8.6, 11.2 and 12.7 μm with weaker and blended features in the 3-20μm region. These features are proposed to arise from the vibrational relaxation of PAH molecules on absorption of background UV photons (Tielens 2008). These IR features have been observed towards almost all types of astronomical objects; say H II regions, photodissociation regions, reflection nebulae, planetary nebulae, young star forming regions, external galaxies, etc. A recent observation has proposed that interstellar PAHs are major reservoir for interstellar deuterium (D) (Peeters et al. 2004). According to the `deuterium depletion model' as suggested by Draine (2006), some of the Ds formed in the big bang are depleted in PAHs, which can account for the present value of D/H in the ISM. Hence, study of deuterated PAHs (PADs) is essential in order to measure D/H in the ISM.In this work, we consider another probable category of the large PAH family, i.e. Deuteronated PAHs (DPAH+). Onaka et al. have proposed a D/H ratio which is an order of magnitude smaller than the proposed value of D/H by Draine suggesting that if Ds are depleted in PAHs, they might be accommodated in large PAHs (Onaka et al. 2014). This work reports a `Density Functional Theory' calculation of large deuteronated PAHs (coronene, ovalene, circumcoronene and circumcircumcoronene) to determine the expected region of emission features and to find a D/H ratio that is comparable to the observational results. We present a detailed analysis of the IR spectra of these molecules and discuss the possible astrophysical implications.ReferencesDraine B. T. 2006, in ASP Conf. Ser. 348, Proc. Astrophysics in the Far Ultraviolet: Five Years of Discovery with FUSE, ed. G. Sonneborn, H. Moos, B-G Andersson (San Francisco, CA:ASP) 58Onaka T., Mori T. I., Sakon I., Ohsawa R., Kaneda H., Okada Y., Tanaka M

  5. Constraining Galaxy Evolution Using Observed UV-Optical Spectra

    NASA Technical Reports Server (NTRS)

    Heap, Sally

    2007-01-01

    Our understanding of galaxy evolution depends on model spectra of stellar populations, and the models are only as good as the observed spectra and stellar parameters that go into them. We are therefore evaluating modem UV-optical model spectra using Hubble's Next Generation Spectral Library (NGSL) as the reference standard. The NGSL comprises intermediate-resolution (R is approximately 1000) STIS spectra of 378 stars having a wide range in metallicity and age. Unique features of the NGSL include its broad wavelength coverage (1,800-10,100 A) and high-S/N, absolute spectrophotometry. We will report on a systematic comparison of model and observed UV-blue spectra, describe where on the HR diagram significant differences occur, and comment on current approaches to correct the models for these differences.

  6. Machine Learning: Quality Control of HST Grism Spectra

    NASA Astrophysics Data System (ADS)

    Stoehr, F.; Walsh, J.; Kuntschner, H.; Rosati, P.; Fosbury, R.; Kümmel, M.; Haase, J.; Hook, R.; Lombardi, M.; Nilsson, K.; Rosa, M.

    2011-07-01

    The Pipeline for Hubble Legacy Archive Grism data (PHLAG) had been used to extract more than 70000 wavelength and flux calibrated 1D spectra. They were obtained from 153 fields observed in G800L grism spectroscopy mode with the Advanced Camera for Surveys on the Hubble Space Telescope. This number of spectra is far too large to allow detailed visual inspection for quality control on reasonable time-scales. As a solution, we use machine learning techniques to classify spectra into "good" and "bad" based on a careful visual inspection of only about 3% of the full sample. A final visual skim through the set of "good" spectra was made to remove catastrophic failures. The remaining 47919 spectra form the largest set of slitless high-level spectroscopic data products publicly released to date.

  7. The first observation of Carbon-13 spin noise spectra

    PubMed Central

    Schlagnitweit, Judith; Müller, Norbert

    2012-01-01

    We demonstrate the first 13C NMR spin noise spectra obtained without any pulse excitation by direct detection of the randomly fluctuating noise from samples in a cryogenically cooled probe. Noise power spectra were obtained from 13C enriched methanol and glycerol samples at 176 MHz without and with 1H decoupling, which increases the sensitivity without introducing radio frequency interference with the weak spin noise. The multiplet amplitude ratios in 1H coupled spectra indicate that, although pure spin noise prevails in these spectra, the influence of absorbed circuit noise is still significant at the high concentrations used. In accordance with the theory heteronuclear Overhauser enhancements are absent from the 1H-decoupled 13C spin noise spectra. PMID:23041799

  8. Recovery of fluctuation spectrum evolution from tomographic shear spectra

    SciTech Connect

    Bonometto, Silvio A.; Mezzetti, Marino E-mail: mezzetti@oats.inaf.it

    2013-05-01

    Forthcoming large angle surveys are planned to obtain high precision tomographic shear data. In principle, they will allow us to recover the spectra of matter density fluctuation, at various redshift, through the inversion of the expressions yielding shear spectra from fluctuation spectra. This was discussed in previous work, where SVD techniques for matrix inversion were also shown to be the optimal tool to this aim. Here we show the significant improvements obtainable by using a 7 bin tomography, as allowed by future Euclid data, and discuss error propagation from shear to fluctuation spectra. We find that the technique is a promising tool, namely for the analysis of baryon physics through high–l shear spectra and to test the consistency between expansion rate and fluctuation growth.

  9. Observations of silicate reststrahlen bands in lunar infrared spectra

    NASA Technical Reports Server (NTRS)

    Potter, A. E., Jr.; Morgan, T. H.

    1982-01-01

    Thermal emission spectra of three lunar sites (Apollo 11, Descartes Formation, and Tycho central peak) are measured in the 8-14 micron spectral range. Transmission and instrument effects are accounted for by forming ratios of the Descartes and Tycho spectra to the Apollo 11 spectrum. The ratio spectra are compared with ratios of published laboratory spectra of returned lunar samples and also with ratio spectra calculated using the Aronson-Emslie (1975) model. The comparisons show pyroxene bands in the Descartes ratio spectrum and plagioclase bands in the Tycho ratio spectrum. The Tycho spectrum is found to be consistent with the existence of fine plagioclase dust (approximately 1 micron) at the rock surface and a higher-than-usual sodium content of the plagioclase.

  10. SPECTRAFACTORY.NET: A DATABASE OF MOLECULAR MODEL SPECTRA

    SciTech Connect

    Cami, J.; Van Malderen, R.; Markwick, A. J. E-mail: Andrew.Markwick@manchester.ac.uk

    2010-04-01

    We present a homogeneous database of synthetic molecular absorption and emission spectra from the optical to mm wavelengths for a large range of temperatures and column densities relevant for various astrophysical purposes, but in particular for the analysis, identification, and first-order analysis of molecular bands in spectroscopic observations. All spectra are calculated in the LTE limit from several molecular line lists, and are presented at various spectral resolving powers corresponding to several specific instrument simulations. The database is available online at http://www.spectrafactory.net, where users can freely browse, search, display, and download the spectra. We describe how additional model spectra can be requested for (automatic) calculation and inclusion. The database already contains over half a million model spectra for 39 molecules (96 different isotopologues) over the wavelength range 350 nm-3 mm ({approx}3-30000 cm{sup -1})

  11. Echo mapping the Balmer-emission region in NGC 3516

    NASA Technical Reports Server (NTRS)

    Wanders, I.; Horne, K.

    1994-01-01

    We use a maximum-entropy method to show that the transfer function (TF) of the broad-line region (BLR) in the Seyfert-1 galaxy NGC 3516 is time-varying. The TF decreased by nearly a factor of two over a time scale less than half a year during a monitoring campaign in 1990. We conclude that the observed time dependency is likely to be either due to variations of the spectral index of the ionizing continuum spectrum; due to a change in the number or covering fraction of broad-line clouds; due to nonlinear line response; or due to nonstationary anisotropy of the continuum source on time scales of several weeks to months. An extended continuum source could also explain the observed time-dependency. The symmetry of the time lag for variations in the red and blue wings of H-alpha indicates that the BLR kinematics is not dominated by organized radial inflow or outflow. If we assume circular orbits, the observed time lag 14 days at velocity v = 4000 km/s suggests a mass of the central object of approximately 2 x 10(exp 7) solar mass. The H-alpha TF peaks away from zero delay, indicating that the H-alpa BLR is either non-spherical or inwardly emitting.

  12. 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 μm. The spectra depend on particle shape. The spectra of the 11, 19, 23, and 33 μm bands, in particular, are extremely sensitive to particle shape, whereas some peaks such as the 11.9, 49, and 69 μm 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 μm, may be due to spherical or spherical-like forsterite.

  13. 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.

  14. An example of scaling MST Doppler spectra using median spectra, spectral smoothing, and velocity tracing

    NASA Technical Reports Server (NTRS)

    Green, J. L.

    1986-01-01

    Although automatic, computer scaling methods appeared at the start of the MST (mesosphere stratosphere troposphere) radar technique, there is a continuing need for scaling algorithms that perform editing functions and increase the sensitivity of radar by post processing. The scaling method presented is an adaptation of the method of scaling MST Doppler spectra presented by Rastogi (1984). A brief overview of this method is as follows: a median spectrum is calculated from several sequential spectra; the median noise value is subtracted from this derived spectrum; the median spectrum is smoothed; the detection/nondetection decision is made by comparing the smoothed spectrum to the variance of the smoothed noise; and if a signal is detected, then the half-power points of the smoothed echo spectrum are used to place limits on the evaluation of the first two moments of the unsmoothed median spectrum. In all of the above steps, the algorithm is guided by tracing the expected velocity range upward from the lowest range as far as possible. The method is discussed in more detail.

  15. Interpretation of Fe-XANES Pre-Edge Spectra: Predictions Based on Co and Fe Optical Spectra

    NASA Technical Reports Server (NTRS)

    Dyar, M. D.; Rossman, G. R.; Delaney, J. S.; Sutton, S. R.; Newville, M.

    2001-01-01

    Microanalysis of Fe-3+/Total(Fe) in extraterrestrial samples is important due to sample size constraints of sample return missions. We compare Fe XANES spectra with Co optical spectra that predict valence electron levels based on 'Z1' model. Additional information is contained in the original extended abstract.

  16. PRINCIPAL COMPONENT ANALYSIS OF SLOAN DIGITAL SKY SURVEY STELLAR SPECTRA

    SciTech Connect

    McGurk, Rosalie C.; Kimball, Amy E.; Ivezic, Zeljko

    2010-03-15

    We apply Principal Component Analysis (PCA) to {approx}100,000 stellar spectra obtained by the Sloan Digital Sky Survey (SDSS). In order to avoid strong nonlinear variation of spectra with effective temperature, the sample is binned into 0.02 mag wide intervals of the g - r color (-0.20 < g - r < 0.90, roughly corresponding to MK spectral types A3-K3), and PCA is applied independently for each bin. In each color bin, the first four eigenspectra are sufficient to describe the observed spectra within the measurement noise. We discuss correlations of eigencoefficients with metallicity and gravity estimated by the Sloan Extension for Galactic Understanding and Exploration Stellar Parameters Pipeline. The resulting high signal-to-noise mean spectra and the other three eigenspectra are made publicly available. These data can be used to generate high-quality spectra for an arbitrary combination of effective temperature, metallicity, and gravity within the parameter space probed by the SDSS. The SDSS stellar spectroscopic database and the PCA results presented here offer a convenient method to classify new spectra, to search for unusual spectra, to train various spectral classification methods, and to synthesize accurate colors in arbitrary optical bandpasses.

  17. THE Be STAR SPECTRA (BeSS) DATABASE

    SciTech Connect

    Neiner, C.; De Batz, B.; Cochard, F.; Floquet, M.; Mekkas, A.; Desnoux, V.

    2011-11-15

    Be stars vary on many timescales, from hours to decades. A long time base of observations to analyze certain phenomena in these stars is therefore necessary. Collecting all existing and future Be star spectra into one database has thus emerged as an important tool for the Be star community. Moreover, for statistical studies, it is useful to have centralized information on all known Be stars via an up-to-date catalog. These two goals are what the Be Star Spectra (BeSS, http://basebe.obspm.fr) database proposes to achieve. The database contains an as-complete-as-possible catalog of known Be stars with stellar parameters, as well as spectra of Be stars from all origins (any wavelength, any epoch, any resolution, etc.). It currently contains over 54,000 spectra of more than 600 different Be stars among the {approx}2000 Be stars in the catalog. A user can access and query this database to retrieve information on Be stars or spectra. Registered members can also upload spectra to enrich the database. Spectra obtained by professional as well as amateur astronomers are individually validated in terms of format and science before being included in BeSS. In this paper, we present the database itself as well as examples of the use of BeSS data in terms of statistics and the study of individual stars.

  18. Fluorescence and reflectance spectra of freshly excised cervical tissue

    NASA Astrophysics Data System (ADS)

    Zelenchuk, Alex R.; Oliva, Esther; Kaufman, Howard; Schomacker, Kevin T.; Bandarchi-Chamkhaleh, Bizhan; Pitts, Jonathan D.

    2002-05-01

    Fluorescence emission and diffuse reflectance spectra of freshly excised cervical tissue were studied with two specially designed contact probes. The objective of the study was to reach a better understanding of the relationship between spectroscopic measurements and cervical tissue morphology. Tissue samples from loop electro-surgical excision and hysterectomy specimens were measured within 20 to 90 minutes of excision. Emission spectra with 337 nm excitation, and reflectance spectra were collected at wavelengths between 370 and 720 nm from different tissue sites. Hematoxylin-eosin stained slides of the measured zones were obtained and compared to the spectra. In one experiment, a contact probe with a central illumination fiber and two concentric rings of detection fibers (radii 0.1 and 1 mm), was placed in contact with the epithelium and used to measure spectra from ectocervix and endocervix. The influence of 5% acetic acid on fluorescence and reflectance spectra was also investigated. In another experiment, a single 100-micron fiber probe was placed perpendicular to a cut edge of tissue and scanned to measure spectra in depth. Depth scans were made over various areas of the cervix

  19. Measurements of Saharan Dust Extinction Spectra in the Infrared

    NASA Astrophysics Data System (ADS)

    Thomas, M.; Gautier, C.; Ricchiazzi, P.; Peterson, P.; Salustro, C.

    2006-12-01

    The infrared extinction spectra of Saharan dust obtained by the Portable Infrared Aerosol Transmission Experiment (PIRATE) are reported in this paper. Saharan dust extinction (optical thickness) spectra from 8 to 13 mm were obtained using solar occultation measurements at Mbour, Senegal in January and March 2006 using a Fourier Transform Infrared (FTIR) spectrometer. The FTIR measured the solar flux in the infrared in the presence of Saharan dust, and the optical thickness was determined by comparing the measured spectra to the modeled spectra without dust for the same solar zenith angle, water vapor concentration and ozone concentration. The modeled spectra were generated using the Santa Barbara Disort Atmospheric Radiative Transfer (SBDART) program. . The infrared optical thickness spectra is compared with modeled optical thickness spectra obtained using Mie theory and dust index of refraction from various sources with assumed log-normal size distributions. Results from these measurements may provide information for improving the remote detection of Saharan dust from space in the infrared using MODIS or AIRS.

  20. [Redshift estimation of galaxy spectra based on similarity measure].

    PubMed

    Liu, Rong; Qiao, Xue-Jun; Duan, Fu-Qing

    2008-01-01

    Automated spectra analysis is desirable and necessary for efficiency of large sky surveys such as SDSS (Sloan digital sky survey), 2DF (2 degree fields) and LAMOST (large sky area multi-object spectroscopic telescope). In the present paper, we present a method for redshift estimation of galaxy spectra based on similarity measure. Firstly, we extract the spectral lines of the observed spectrum using the feature constrains of spectral lines; secondly, the authors determine the redshift candidates of the observed spectrum by spectral line features; then, the similarity between the observed spectrum and the template spectra shifted by each redshift candidate is measured; finally, the candidate of the highest similarity is chosen as the estimated redshift. PCA (principal component analysis) is used to build the static galaxy template spectra. The authors perform PCA for the four template spectra E, S0, Sa and Sb of the normal galaxy and the seven template spectra Sc, Sb1, Sb2, Sb3, Sb4, Sb5 and Sb6 of the starburst galaxy respectively, where the eleven template spectra are presented by Kinney & Calzetti et al. Two eigen-spectra are produced with the variance contribution rate of 99%. The authors choose the two eigen-spectra as the galaxy templates. The similarity measure proposed, which is similar to the evidence accumulation, is defined as the weighted sum of several similarity evidences. It can reduce the influence caused by some error matching. The authors divide the observed spectrum and the template spectrum respectively into several parts, and measure the correlations of the corresponding parts of them, which is chosen as the similarity evidences in the proposed similarity measure. The principle of setting the weights is that the higher the correlation, the higher the corresponding weight. The proposed approach is compared with the method based on spectral line matching and the traditional cross correlation technique by experiments, the results show that the

  1. LET spectra measurements from the STS-35 CPDs

    SciTech Connect

    1995-03-01

    Linear energy transfer (LET) spectra derived form automated track analysis system (ATAS) track parameter measurements for crew passive dosimeters (CPD`s) flown with the astronauts on STS-35 are plotted. The spread between the seven individual spectra is typical of past manual measurements of sets of CPD`s. This difference is probably due to the cumulative net shielding variations experienced by the CPD`s as the astronauts carrying them went about their activities on the Space Shuttle. The STS-35 mission was launched on Dec. 2, 1990, at 28.5 degrees inclination and 352-km altitude. This is somewhat higher than the nominal 300-km flights and the orbit intersects more of the high intensity trapped proton region in the South Atlantic Anomaly (SAA). However, in comparison with APD spectra measured on earlier lower altitude missions (STS-26, -29, -30, -32), the flux spectra are all roughly comparable. This may be due to the fact that the STS-35 mission took place close to solar maximum (Feb. 1990), or perhaps to shielding differences. The corresponding dose and dose equivalent spectra for this mission are shown. The effect of statistical fluctuations at the higher LET values, where track densities are small, is very noticeable. This results in an increased spread within the dose rate and dose equivalent rate spectra, as compared to the flux spectra. The contribution to dose and dose equivalent per measured track is much greater in the high LET region and the differences, though numerically small, are heavily weighted in the integral spectra. The optimum measurement and characterization of the high LET tails of the spectra represent an important part of the research into plastic nuclear track detector (PNTD) response. The integral flux, dose rate, dose equivalent rate and mission dose equivalent for the seven astronauts are also given.

  2. Study on Properties of Energy Spectra of the Molecular Crystals

    NASA Astrophysics Data System (ADS)

    Pang, Xiao-Feng; Chen, Xiang-Rong

    The energy-spectra of nonlinear vibration of molecular crystals such as acetanilide have been calculated by using discrete nonlinear Schrödinger equation appropriate to the systems, containing various interactions. The energy levels including higher excited states are basically consistent with experimental values obtained by infrared absorption and Raman scattering in acetanilide. We further give the features of distribution of the energy-spectra for the acetanilide. Using the energy spectra we also explained well experimental results obtained by Careri et al..

  3. Pulsar gamma-rays: Spectra luminosities and efficiencies

    NASA Technical Reports Server (NTRS)

    Harding, A. K.

    1980-01-01

    The general characteristics of pulsar gamma ray spectra are presented for a model where the gamma rays are produced by curvature radiation from energetic particles above the polar cap and attenuated by pair production. The shape of the spectrum is found to depend on pulsar period, magnetic field strength, and primary particle energy. By a comparison of numerically calculated spectra with the observed spectra of the Crab and Vela pulsars, it is determined that primary particles must be accelerated to energies of about 3 x 10 to the 7th power mc sq. A genaral formula for pulsar gamma ray luminosity is determined and is found to depend on period and field strength.

  4. 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.

  5. Vibrational and VCD spectra of poly(menthyl vinyl ether)

    NASA Astrophysics Data System (ADS)

    McCann, J. L.; Bour, P.; Wieser, H.

    1998-06-01

    The detailed assignments are reported for the vibrational and VCD spectra of (1S,2R,5S)-(+)-menthol. Energy minimized geometries, harmonic force fields, and atomic polar tensors were calculated at the Becke3LYP/6-31G** level, and atomic axial tensors with the vibronic coupling theory at the HF/6-31G level. The spectra consist of contributions mainly from two isomers (70%) distinguished only by conformation of the OH group. An attempt was made to simulate the absorption and VCD spectra of poly(methyl vinyl ether) using a component approach and invoking the excitation scheme with promising though not conclusive results at this stage.

  6. Small-World Network Spectra in Mean-Field Theory

    NASA Astrophysics Data System (ADS)

    Grabow, Carsten; Grosskinsky, Stefan; Timme, Marc

    2012-05-01

    Collective dynamics on small-world networks emerge in a broad range of systems with their spectra characterizing fundamental asymptotic features. Here we derive analytic mean-field predictions for the spectra of small-world models that systematically interpolate between regular and random topologies by varying their randomness. These theoretical predictions agree well with the actual spectra (obtained by numerical diagonalization) for undirected and directed networks and from fully regular to strongly random topologies. These results may provide analytical insights to empirically found features of dynamics on small-world networks from various research fields, including biology, physics, engineering, and social science.

  7. Computer Processing Of Tunable-Diode-Laser Spectra

    NASA Technical Reports Server (NTRS)

    May, Randy D.

    1991-01-01

    Tunable-diode-laser spectrometer measuring transmission spectrum of gas operates under control of computer, which also processes measurement data. Measurements in three channels processed into spectra. Computer controls current supplied to tunable diode laser, stepping it through small increments of wavelength while processing spectral measurements at each step. Program includes library of routines for general manipulation and plotting of spectra, least-squares fitting of direct-transmission and harmonic-absorption spectra, and deconvolution for determination of laser linewidth and for removal of instrumental broadening of spectral lines.

  8. Copper(II) phthalocyanine: Electronic and vibrational tunneling spectra

    SciTech Connect

    Hipps, K.W. )

    1989-08-10

    Inelastic electron tunneling spectra (IETS) obtained from Al-AlO{sub x}-CuPc-M junctions (M = Pb or Tl) are presented and compared with previous reports. Improved experimental methods allow them to report the entire spectrum in the region below 16,000 cm{sup {minus}1} in both bias directions. In contrast to previous studies, they will show that (a) tunneling spectra are very dependent upon the AlO{sub x}/CuPc and CuPc/M imbedded interfaces, (b) spectra contain both temperature-dependent and temperature-independent features, and (c) certain electronic and the vibrational features depend on junction bias.

  9. Ferromagnetic resonance spectra of H2-reduced minerals and glasses

    NASA Technical Reports Server (NTRS)

    Morris, Richard V.; Allen, Carlton C.

    1994-01-01

    In an earlier paper, we reported that H2 reduction of basaltic glass, olivine, pyroxene, and plagioclase resulted in the formation of metallic iron, in the darkening and reddening of the reflectance spectra, and the masking of individual spectral features in the visible and near-IR. In this work, we report FMR spectra for H2-reduced minerals and glasses that include the samples studied in the earlier paper. The FMR spectra were reduced at room temperature at a nominal frequency of 9.5 GHz. Sample saturation magnetization reported as F3(0) was measured with a vibrating sample magnetometer.

  10. The analysis of spectra of novae taken near maximum

    NASA Technical Reports Server (NTRS)

    Stryker, L. L.; Hestand, J.; Starrfield, S.; Wehrse, R.; Hauschildt, P.; Spies, W.; Baschek, B.; Shaviv, G.

    1988-01-01

    A project to analyze ultraviolet spectra of novae obtained at or near maximum optical light is presented. These spectra are characterized by a relatively cool continuum with superimposed permitted emission lines from ions such as Fe II, Mg II, and Si II. Spectra obtained late in the outburst show only emission lines from highly ionized species and in many cases these are forbidden lines. The ultraviolet data will be used with calculations of spherical, expanding, stellar atmospheres for novae to determine elemental abundances by spectral line synthesis. This method is extremely sensitive to the abundances and completely independent of the nebular analyses usually used to obtain novae abundances.

  11. Far infrared spectra of metal complexes in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Carr, C.; Goggin, P. L.

    Using F.t.i.r. and multiple acquisition methods, far i.r. spectra with fairly good S/N ratios can be obtained from aqueous solutions in about 4 hours. Spectra are presented for some concentrated ruthenium(III) chloride systems where the colour precludes Raman spectroscopy. To obtain spectra without interference from water or hydrated cations, quantitative subtraction techniques are employed for separate removal of each component. Results are presented for some indium(III) halide and gallium(III) bromide systems.

  12. Simple posterior frequency correction for vibrational spectra from molecular dynamics

    NASA Astrophysics Data System (ADS)

    Tikhonov, Denis S.

    2016-05-01

    Vibrational spectra computed from molecular dynamics simulations with large integration time steps suffer from nonphysical frequency shifts of signals [M. Praprotnik and D. Janežič, J. Chem. Phys. 122, 174103 (2005)]. A simple posterior correction technique was developed for compensation of this behavior. It performs through replacement of abscissa in the calculated spectra using following formula: ν corrected = /√{ 2 ṡ (" separators=" 1 - cos ( 2 π ṡ Δ t ṡ ν initial ) ) } 2 π ṡ Δ t , where ν are initial and corrected frequencies and Δt is the MD simulation time step. Applicability of this method was tested on gaseous infrared spectra of hydrogen fluoride and formic acid.

  13. Electron energy-loss spectra in molecular fluorine

    NASA Technical Reports Server (NTRS)

    Nishimura, H.; Cartwright, D. C.; Trajmar, S.

    1979-01-01

    Electron energy-loss spectra in molecular fluorine, for energy losses from 0 to 17.0 eV, have been taken at incident electron energies of 30, 50, and 90 eV and scattering angles from 5 to 140 deg. Features in the spectra above 11.5 eV energy loss agree well with the assignments recently made from optical spectroscopy. Excitations of many of the eleven repulsive valence excited electronic states are observed and their location correlates reasonably well with recent theoretical results. Several of these excitations have been observed for the first time and four features, for which there are no identifications, appear in the spectra.

  14. Automated Endmember Selection for Nonlinear Unmixing of Lunar Spectra

    NASA Astrophysics Data System (ADS)

    Felder, M. P.; Grumpe, A.; Wöhler, C.; Mall, U.

    2013-09-01

    An important aspect of the analysis of remotely sensed lunar reflectance spectra is their decomposition into intimately mixed constituents. While some methods rely on unmixing of the observed reflectance spectra [1] or on the identification of minerals by extracting the depths and positions of mineral-specific absorption troughs [2, 3], these approaches do not allow for an automated selection of the (a priori unknown) endmembers from a large set of possible constituents. In this study, a non-linear spectral unmixing approach combined with an automated endmember selection scheme is proposed. This method is applied to reflectance spectra of the SIR-2 point spectrometer [4] carried by the Chandrayaan-1 spacecraft.

  15. Thermo-Reflectance Spectra of Eros: Unambiguous Detection of Olivine

    NASA Technical Reports Server (NTRS)

    Lucey, P. G.; Hinrichs, J. L.; Urquhart-Kelly, M.; Wellnitz, D.; Bell, J. F., III; Clark, B. E.

    2001-01-01

    Olivine is readily detected on 433 Eros using the new thermo-reflectance spectral technique applied to near-IR spectra obtained at Eros by the NEAR spacecraft. Additional information is contained in the original extended abstract.

  16. Structural Analysis of Dusty Plasma Formations Based on Spatial Spectra

    SciTech Connect

    Khakhaev, A. D.; Luizova, L. A.; Piskunov, A. A.; Podryadchikov, S. F.; Soloviev, A. V.

    2008-09-07

    Some advantages of studying the structure of dusty plasma formations using spatial spectra are illustrated by simulated experiments and by processing actual images of dusty structures in dc glow discharge in inert and molecular gases.

  17. Infrared spectra of jennite and tobermorite from first-principles

    SciTech Connect

    Vidmer, Alexandre Sclauzero, Gabriele; Pasquarello, Alfredo

    2014-06-01

    The infrared absorption spectra of jennite, tobermorite 14 Å, anomalous tobermorite 11 Å, and normal tobermorite 11 Å are simulated within a density-functional-theory scheme. The atomic coordinates and the cell parameters are optimized resulting in structures which agree with previous studies. The vibrational frequencies and modes are obtained for each mineral. The vibrational density of states is analyzed through extensive projections on silicon tetrahedra, oxygen atoms, OH groups, and water molecules. The coupling with the electric field is achieved through the use of density functional perturbation theory, which yields Born effective charges and dielectric constants. The simulated absorption spectra reproduce well the experimental spectra, thereby allowing for a detailed interpretation of the spectral features in terms of the underlying vibrational modes. In the far-infrared part of the absorption spectra, the interplay between Ca and Si related vibrations leads to differences which are sensitive to the calcium/silicon ratio of the mineral.

  18. Chemical decomposition by normalization of millimeter-wave spectra

    SciTech Connect

    Gopalan, K.; Gopalsami, N.

    1996-10-01

    The sharp, distinct absorption spectra of chemicals at low pressures in the mm wave range become broadened at high pressures, so that detecting and quantifying different chemicals at high pressures become difficult. This paper proposes a method of decomposition based on the low pressure spectra. Normalized low pressure spectral amplitudes are used as features to train a neural network. The network is tested using the peak spectra obtained for an unknown plume of chemicals at high pressure. Initial tests conducted on simulated and experimental spectra of selected chemicals show that the decomposition results of the proposed method are dependent on the dominance of the chemicals in the mixture - a characteristic common to conventional methods of decomposition.

  19. The GIRAFFE Archive: 1D and 3D Spectra

    NASA Astrophysics Data System (ADS)

    Royer, F.; Jégouzo, I.; Tajahmady, F.; Normand, J.; Chilingarian, I.

    2013-10-01

    The GIRAFFE Archive (http://giraffe-archive.obspm.fr) contains the reduced spectra observed with the intermediate and high resolution multi-fiber spectrograph installed at VLT/UT2 (ESO). In its multi-object configuration and the different integral field unit configurations, GIRAFFE produces 1D spectra and 3D spectra. We present here the status of the archive and the different functionalities to select and download both 1D and 3D data products, as well as the present content. The two collections are available in the VO: the 1D spectra (summed in the case of integral field observations) and the 3D field observations. These latter products can be explored using the VO Paris Euro3D Client (http://voplus.obspm.fr/ chil/Euro3D).

  20. Measuring Complex Sum Frequency Spectra with a Nonlinear Interferometer.

    PubMed

    Wang, Jing; Bisson, Patrick J; Marmolejos, Joam M; Shultz, Mary Jane

    2016-06-01

    Currently, the only techniques capable of delivering molecular-level data on buried or soft interfaces are the nonlinear spectroscopic methods: sum frequency generation (SFG) and second harmonic generation (SHG). Deducing molecular information from spectra requires measuring the complex components-the amplitude and the phase-of the surface response. A new interferometer has been developed to determine these components with orders-of-magnitude improvement in uncertainty compared with current methods. Both the sample and reference spectra are generated within the interferometer, hence the label nonlinear interferometer. The interferometer configuration provides experimenters with wide latitude for both the sample enclosure and reference material choice and is thus widely applicable. The instrument is described and applied to the well-studied octadecyltrichlorosilane (OTS) film. The OTS spectra support the interpretation that variation in fabrication solvent water content and substrate preparation account for differences in OTS spectra reported in the literature. PMID:27159338

  1. Infrared transmission spectra of Sea of Fertility regolith

    NASA Technical Reports Server (NTRS)

    Akhmanova, M. V.; Karyakin, A. V.; Tartasov, L. S.

    1974-01-01

    Transmission spectra in the 2-25 micrometer region were obtained for samples of lunar regolith returned by the Luna 16 automatic station. A comparison of the Luna 16, Apollo 11, and Apollo 12 samples showed that the infrared transmission spectra of regolith samples from the mare regions are similar and characteristic of basic basaltic rocks. The absorption bands show up in the vibration region of the SiO4 groups. No water and OH groups were found in the samples based on the spectrum. Spectra of regolith samples calcined at 1000C showed changes that can be interpreted as changes in the spectra of irradiated crystals (especially distinctly for the Luna 16 samples).

  2. INFRARED SPECTRA OF ISOLATED PROTONATED POLYCYCLIC AROMATIC HYDROCARBON MOLECULES

    SciTech Connect

    Knorke, Harald; Langer, Judith; Dopfer, Otto; Oomens, Jos

    2009-11-20

    Gas-phase infrared (IR) spectra of larger protonated polycyclic aromatic hydrocarbon molecules, H{sup +}PAH, have been recorded for the first time. The ions are generated by electrospray ionization and spectroscopically assayed by IR multiple-photon dissociation (IRMPD) spectroscopy in a Fourier transform ion cyclotron resonance mass spectrometer using a free electron laser. IRMPD spectra of protonated anthracene, tetracene, pentacene, and coronene are presented and compared to calculated IR spectra. Comparison of the laboratory IR spectra to an astronomical spectrum of the unidentified IR emission (UIR) bands obtained in a highly ionized region of the interstellar medium provides for the first time compelling spectroscopic support for the recent hypothesis that H{sup +}PAHs contribute as carriers of the UIR bands.

  3. FTIR Spectra of Possible End Products of Martian Surface Weathering

    NASA Astrophysics Data System (ADS)

    Maxe, L. P.

    2008-03-01

    Comparative analysis of IR spectra shows that martian weathering can lead to separating destruction of surface rocks. The semi-cosmic martian weathering results in amorphous silica dust and open unique ferry aluminum/ferry silicate martian rocks.

  4. Atmospheric CO2 retrieved from ground-based solar spectra

    NASA Technical Reports Server (NTRS)

    Yang, Z.; Toon, G. C.; Margolis, J. S.; Wennberg, P. O.

    2002-01-01

    The column-averaged volume mixing ration of CO2 over Kitt Peak, Arizona, has been retrieved from high-resolution solar absorption spectra obtained with the fourier transform spectrometer on the McMath telescope.

  5. Composite load spectra for select space propulsion structural components

    NASA Technical Reports Server (NTRS)

    Newell, J. F.

    1987-01-01

    The objective of this program is to develop generic load models to simulate the composite load spectra (CLS) that are induced in space propulsion system components representative of the space shuttle main engines (SSME). These models are being developed through describing individual component loads with an appropriate mix of deterministic and state-of-the-art probabilistic models that are related to key generic variables. Combinations of the individual loads are used to synthesize the composite loads spectra. A second approach for developing the composite loads spectra load model simulation, the option portion of the contract will develop coupled models which combine the individual load models. Statistically varying coefficients of the physical models will be used to obtain the composite load spectra.

  6. Mammography X-Ray Spectra Simulated with Monte Carlo

    SciTech Connect

    Vega-Carrillo, H. R.; Gonzalez, J. Ramirez; Manzanares-Acuna, E.; Hernandez-Davila, V. M.; Villasana, R. Hernandez; Mercado, G. A.

    2008-08-11

    Monte Carlo calculations have been carried out to obtain the x-ray spectra of various target-filter combinations for a mammography unit. Mammography is widely used to diagnose breast cancer. Further to Mo target with Mo filter combination, Rh/Rh, Mo/Rh, Mo/Al, Rh/Al, and W/Rh are also utilized. In this work Monte Carlo calculations, using MCNP 4C code, were carried out to estimate the x-ray spectra produced when a beam of 28 keV electrons did collide with Mo, Rh and W targets. Resulting x-ray spectra show characteristic x-rays and continuous bremsstrahlung. Spectra were also calculated including filters.

  7. Locally linear embedding: dimension reduction of massive protostellar spectra

    NASA Astrophysics Data System (ADS)

    Ward, J. L.; Lumsden, S. L.

    2016-09-01

    We present the results of the application of locally linear embedding (LLE) to reduce the dimensionality of dereddened and continuum subtracted near-infrared spectra using a combination of models and real spectra of massive protostars selected from the Red MSX Source survey data base. A brief comparison is also made with two other dimension reduction techniques; principal component analysis (PCA) and Isomap using the same set of spectra as well as a more advanced form of LLE, Hessian locally linear embedding. We find that whilst LLE certainly has its limitations, it significantly outperforms both PCA and Isomap in classification of spectra based on the presence/absence of emission lines and provides a valuable tool for classification and analysis of large spectral data sets.

  8. Power spectra at radio frequency of lightning return stroke waveforms

    NASA Technical Reports Server (NTRS)

    Lanzerotti, L. J.; Thomson, D. J.; Maclennan, C. G.; Rinnert, K.; Krider, E. P.

    1989-01-01

    The power spectra of the wideband (10 Hz to 100 kHz) magnetic field signals in a number of lightning return strokes (primarily first return strokes) measured during a lightning storm which occurred in Lindau, West Germany in August, 1984 have been calculated. The RF magnetic field data were obtained with the engineering unit of the Galileo Jupiter Probe lightning experiment. The spectra of the magnetic field data definitely show fine structure, with two or three distinct peaks appearing in the spectra of many of the waveforms. An enhancement of power at frequencies of about 60-70 kHz is often seen in the spectra of the waveform time segments preceding and following the rise-to-peak amplitude of the return stroke.

  9. Far-infrared reflectance spectra of optical black coatings

    NASA Technical Reports Server (NTRS)

    Smith, S. M.

    1983-01-01

    Far-infrared specular reflectance spectra of six optically black coatings near normal incidence are presented. The spectra were obtained using nine bandpass transmission filters in the wavelength range between 12 and 300 microns. Data on the construction, thickness, and rms surface roughness of the coatings are also presented. The chemical composition of two coatings can be distinguished from that of the others by a strong absorption feature between 20 and 40 microns which is attributed to amorphous silicate material. Inverse relationships between these spectra and coating roughness and thickness are noted and lead to development of a reflecting-layer model for the measured reflectance. The model is applied to the spectra of several coatings whose construction falls within its constraints.

  10. Online Spectral Fit Tool for Analyzing Reflectance Spectra

    NASA Astrophysics Data System (ADS)

    Penttilä, A.; Kohout, T.

    2015-11-01

    The Online Spectral Fit Tool is developed for analyzing Vis-NIR spectral behavior of asteroids and meteorites. Implementation is done using JavaScript/HTML. Fitted spectra consist of spline continuum and gamma distributions for absorption bands.

  11. 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.

  12. 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.

  13. Solvent effect on the vibrational spectra of Carvedilol

    NASA Astrophysics Data System (ADS)

    Billes, Ferenc; Pataki, Hajnalka; Unsalan, Ozan; Mikosch, Hans; Vajna, Balázs; Marosi, György

    2012-09-01

    Carvedilol (CRV) is an important medicament for heart arrhythmia. The aim of this work was the interpretation of its vibrational spectra with consideration on the solvent effect. Infrared and Raman spectra were recorded in solid state as well in solution. The experimental spectra were evaluated using DFT quantum chemical calculations computing the optimized structure, atomic net charges, vibrational frequencies and force constants. The same calculations were done for the molecule in DMSO and aqueous solutions applying the PCM method. The calculated force constants were scaled to the experimentally observed solid state frequencies. The characters of the vibrational modes were determined by their potential energy distributions. Solvent effects on the molecular properties were interpreted. Based on these results vibrational spectra were simulated.

  14. Reflectance Spectra of Members of Very Young Asteroid Families

    NASA Astrophysics Data System (ADS)

    Chapman, C. R.; Enke, B.; Merline, W. J.; Nesvorný, D.; Tamblyn, P.; Young, E. F.

    2009-03-01

    We present SpeX infrared spectra for members of the dynamically young Datura, Iannini, Karin, and Veritas asteroid families (plus Koronis and Themis family controls). S-types are space-weathered on timescales of a few million years.

  15. Microwave spectra of some chlorine and fluorine compounds. [spectroscopic analysis

    NASA Technical Reports Server (NTRS)

    White, W. F.

    1975-01-01

    A computer-controlled microwave spectrometer was used to catalog reference spectra for chemical analysis. Tables of absorption frequencies, peak absorption intensities, and integrated intensities are shown for 21 organic compounds which contain chlorine, fluorine, or both.

  16. Infrared spectra of olivine polymorphs - Alpha, beta phase and spinel

    NASA Technical Reports Server (NTRS)

    Jeanloz, R.

    1980-01-01

    The infrared absorption spectra of several olivines (alpha phase) and their corresponding beta phase (modified spinel) and spinel (gamma) high-pressure polymorphs are determined. Spectra were measured for ground and pressed samples of alpha and gamma A2SiO4, where A = Fe, Ni, Co; alpha and gamma Mg2GeO4; alpha Mg2SiO4; and beta Co2SiO4. The spectra are interpreted in terms of internal, tetrahedral and octagonal, and lattice vibration modes, and the spinel results are used to predict the spectrum of gamma Mg2SiO4. Analysis of spectra obtained from samples of gamma Mg2GeO4 heated to 730 and 1000 C provides evidence that partial inversion could occur in silicate spinels at elevated temperatures and pressures.

  17. Laboratory spectra of C60 and related molecular structures

    NASA Technical Reports Server (NTRS)

    Janca, J.; Solc, M.; Vetesnik, M.

    1994-01-01

    The electronic spectra of fullerene structures in high frequency discharge are studied in the plasma chemistry laboratory of the Faculty of Science of Masaryk University in Brno. The ultraviolet and visual spectra are investigated in order to be compared with the diffuse interstellar bands and interpreted within the theory of quantum mechanics. The preliminary results of the study are presented here in the form of a poster.

  18. Electronic and vibrational circular dichroism spectra of (R)-(-)-apomorphine

    NASA Astrophysics Data System (ADS)

    Abbate, Sergio; Longhi, Giovanna; Lebon, France; Tommasini, Matteo

    2012-09-01

    Apomorphine is a chiral drug molecule; notwithstanding its extraordinary importance, little attention has been paid to the characterization of its chiroptical properties. Here we report on its electronic circular dichroism (ECD) spectra, recorded in methanol and water, and vibrational circular dichroism (VCD) in methanol and dimethyl sulfoxide (DMSO) solutions. Density functional theory (DFT) calculations have allowed us to interpret the spectra and to evaluate the role of possible conformations, charge-states and interactions with counter ions.

  19. Numerical analysis of EPR spectra. 8. Relative concentrations

    NASA Astrophysics Data System (ADS)

    Beckwith, Athelstan L. J.; Brumby, Steven

    A method for determining the relative concentrations of paramagnetic species in mixtures by least-squares analysis of the EPR spectra is described. The method is especially useful when the double integration method cannot be used because of overlap between the component spectra. In two examples, the relative steady-state concentrations of free radicals formed during the photolysis of dimethoxymethane/di- tert-butyl peroxide and cyclopropylmethyl methyl ether/di- tert-butyl peroxide/cyclopropane solutions are determined.

  20. Space Shuttle fatigue loads spectra for prelaunch and liftoff loads

    NASA Technical Reports Server (NTRS)

    Goldish, Judith; Ortasse, Raphael

    1994-01-01

    Fatigue loads spectra for the prelaunch and liftoff flight segments of the Space Shuttle were developed. A variety o methods were used to determine the distributions of several important parameters, such as time of exposure on the launch, pad, month of launch, and wind speed. Also, some lessons learned that would be applicable to development of fatigue loads spectra for other reusable space vehicles are presented.