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Sample records for balmer spectra

  1. 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.

  2. MASSIVE AND NEWLY DEAD: DISCOVERY OF A SIGNIFICANT POPULATION OF GALAXIES WITH HIGH-VELOCITY DISPERSIONS AND STRONG BALMER LINES AT z {approx} 1.5 FROM DEEP KECK SPECTRA AND HST/WFC3 IMAGING

    SciTech Connect

    Bezanson, Rachel; Van Dokkum, Pieter; Van de Sande, Jesse; Franx, Marijn; Kriek, Mariska

    2013-02-10

    We present deep Keck/LRIS spectroscopy and Hubble Space Telescope/WFC3 imaging in the rest-frame optical for a sample of eight galaxies at z {approx} 1.5 with high photometrically determined stellar masses. The data are combined with five Very Large Telescope/X-Shooter spectra. We find that these 13 galaxies have high velocity dispersions, with a median of {sigma} = 301 km s{sup -1}. This high value is consistent with their relatively high stellar masses and compact sizes. We study their stellar populations using the strength of Balmer absorption lines, which are not sensitive to dust absorption. We find a large range in Balmer absorption strength, with many galaxies showing very strong lines indicating young ages. The median H{delta}{sub A} equivalent width, determined directly or inferred from the H10 line, is 5.4 A, indicating a luminosity-weighted age of {approx}1 Gyr. Although this value may be biased toward higher values because of selection effects, high-dispersion galaxies with such young ages are extremely rare in the local universe. Interestingly, we do not find a simple correlation with rest-frame U - V color: some of the reddest galaxies have very strong Balmer absorption lines, which may indicate the importance of multiple bursts of star formation. These results demonstrate that many high-dispersion galaxies at z {approx} 1.5 were recently quenched. This implies that there must be a population of star-forming progenitors at z {approx} 2 with high velocity dispersions or linewidths, which are notoriously absent from CO/H{alpha} selected surveys.

  3. Modelado del continuo de Balmer en estrellas Be

    NASA Astrophysics Data System (ADS)

    Cruzado, A.; Bibbó, I.; Ringuelet, A.

    The second Balmer jump is a distinctive spectral feature very often observed in Be stars. This jump, which is usually attributed to a surrounding extended envelope, may be in emission or in absorption. So, an excess or defect of radiation relative to theoretical atmospheric models describing early-type spectra is originated in the Balmer continuum region. The aim of the present work is to account for the different aspects shown by the Balmer continuum in Be stars. In order to do that, models have been built by adopting different density and temperature distributions and by taking into account every physical process that may take place in extended envelopes of Be stars.

  4. 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.

  5. Understanding the Balmer Bubble in the Vela Supernova Remnant

    NASA Astrophysics Data System (ADS)

    Chinn, Brian; Smith, C.; Points, S.; Heathcote, S.

    2014-01-01

    We present imaging and spectroscopic data and analysis of the Balmer-dominated filament that is ahead of the eastern edge of the radiative shock of Bullet C in the Vela Supernova Remnant. This filament was discovered in 2002 by Carlin & Smith(2002), and was suggested to be a non-radiative shock. Images of the filament were taken using Hα and R band filters on the SMARTS 0.9m telescope at CTIO. These images were then compared to images taken in 2006 using the MOSAIC II imager on the Blanco Telescope at CTIO, in an attempt to detect proper motion of the filament. Comparison over the 7 year baseline failed to show proper motion of the filament. From this result, we are able to place an upper limit of ~270 km/s on the velocity of the Balmer-dominated filament. We also obtained moderate resolution spectra of the Balmer-dominated filament and the radiative shock using the Goodman Spectrograph at SOAR Telescope. Spectroscopic analysis of the Balmer-dominated filament failed to detect a broad component of the Hα emission line, which would be expected for a high velocity non-radiative shock.

  6. 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.

  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. 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.

  11. Geocoronal Balmer-alpha Emission Observed by the Wisconsin H-Alpha Mapper During the Southern Sky Survey

    NASA Astrophysics Data System (ADS)

    Mierkiewicz, E. J.; Haffner, L. M.; Nossal, S. M.; Wilson, M. L.; Freer, C. W.; Babler, B.; Gardner, D.; Roesler, F. L.

    2015-12-01

    After a successful eleven-year run at Kitt Peak Observatory (AZ), the Wisconsin H-Alpha Mapper (WHAM) was moved to Cerro Tololo (Chile) in 2009 to complete the southern portion of the Galactic Balmer-alpha survey. Although WHAM is primarily used for making observations of the interstellar medium, the terrestrial emission present in each of WHAM's astronomical spectra offers a rich resource for studying the Earth's atmosphere. Here we present an overview of the terrestrial Balmer-alpha emission collected during WHAM's first five years of operation under southern skies. Seasonal trends and comparisons with northern hemisphere observations will be discussed. WHAM can detect Balmer-alpha emission as faint as 0.05R in a 30s exposure, covering a 200 km/s (4.4 Angstrom) spectral region with 12 km/s spectral resolution from a 1 degree beam on the sky. With this sensitivity, hundreds of spectra can be collected in a single clear night. Although not capable of fully resolving the geocoronal Balmer-alpha line profile itself, WHAM's sensitivity makes it an exceptional instrument for geocoronal Balmer-alpha intensity observations. This work is supported by NSF award AGS-1352311 and AST-1108911.

  12. 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.

  13. Balmer line profiles for infalling T Tauri envelopes

    NASA Technical Reports Server (NTRS)

    Calvet, Nuria; Hartmann, Lee

    1992-01-01

    The possibility that the Balmer emission lines of T Tauri stars arise in infalling envelopes rather than winds is considered. Line profiles for the upper Balmer lines are presented for models with cone geometry, intended to simulate the basic features of magnetospheric accretion from a circumstellar disk. An escape probability treatment is used to determine line source functions in nonspherically symmetric geometry. Thermalization effects are found to produce nearly symmetric H-alpha line profiles at the same time the higher Balmer series lines exhibit inverse P Cygni profiles. The infall models produce centrally peaked emission line wings, in good agreement with observations of many T Tauri stars. It is suggested that the Balmer emission of many T Tauri stars may be produced in an infalling envelope, with blue shifted absorption contributed by an overlying wind. Some of the observed narrow absorption components with small blueshifts may also arise in the accretion column.

  14. 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.

  15. Measurement of the deuterium Balmer series line emission on EAST

    NASA Astrophysics Data System (ADS)

    Wu, C. R.; Huang, J.; Gao, W.; Gao, W.; Xu, Z.; Chang, J. F.; Hou, Y. M.; Jin, Z.; Xu, J. C.; Duan, Y. M.; Zhang, P. F.; Chen, Y. J.; Zhang, L.; Wu, Z. W.; Li, J. G.

    2016-11-01

    Volume recombination plays an important role towards plasma detachment for magnetically confined fusion devices. High quantum number states of the Balmer series of deuterium are used to study recombination. On EAST (Experimental Advanced Superconducting Tokamak), two visible spectroscopic measurements are applied for the upper/lower divertor with 13 channels, respectively. Both systems are coupled with Princeton Instruments ProEM EMCCD 1024B camera: one is equipped on an Acton SP2750 spectrometer, which has a high spectral resolution ˜0.0049 nm with 2400 gr/mm grating to measure the Dα(Hα) spectral line and with 1200 gr/mm grating to measure deuterium molecular Fulcher band emissions and another is equipped on IsoPlane SCT320 using 600 gr/mm to measure high-n Balmer series emission lines, allowing us to study volume recombination on EAST and to obtain the related line averaged plasma parameters (Te, ne) during EAST detached phases. This paper will present the details of the measurements and the characteristics of deuterium Balmer series line emissions during density ramp-up L-mode USN plasma on EAST.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. Discovery of Extremely Broad Balmer Absorption Lines in SDSS J152350.42+391405.2

    NASA Astrophysics Data System (ADS)

    Zhang, Shaohua; Zhou, Hongyan; Shi, Xiheng; Shu, Xinwen; Liu, Wenjuan; Ji, Tuo; Jiang, Peng; Sun, Luming; Zhou, Junyan; Pan, Xiang

    2015-12-01

    We present the discovery of Balmer line absorption from Hα to Hγ in an iron low-ionization broad absorption line (FeLoBAL) quasar SDSS J152350.42+391405.2 (hereafter SDSS J1523+3914), by the quasi-simultaneous optical and near-infrared spectroscopy. The Balmer line absorption is at {z}{absor}=0.6039+/- 0.0021 and blueshifted by v = 10,353 km s-1 with respect to the Balmer emission lines. All Balmer BALs have a uniform absorption profile with the widths of {{Δ }}v˜ 12,000 km s-1. We also found the absorption trough in He i* λ10830 with the same velocity and width in the H-band TripleSpec spectrum of SDSS J1523+3914. This object is only the 10th active galactic nucleus known to exhibit nonstellar Balmer absorption, as well as the case with the highest velocity and broadest Balmer absorption lines that have ever been found. A CLOUDY analysis shows that the absorbers require a gas density of {{log}}10 {n}{{e}} ({{cm}}-3)=9 and an ionization parameter of {{log}}10 U=-1.0. They are located at a distance of ˜0.2 pc from the central ionizing source, which is slightly farther than that of broad emission line regions. Furthermore, SDSS J1523+3914 is one of the brightest Balmer BAL quasars ever reported, with unique iron absorption variations, making it the most promising candidate for follow-up high-resolution spectroscopy, multiband observations, and long-term monitoring.

  1. 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.

  2. 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.

  3. Geocoronal Balmer α line profile observations and forward-model analysis

    NASA Astrophysics Data System (ADS)

    Mierkiewicz, E. J.; Bishop, J.; Roesler, F. L.; Nossal, S. M.

    2006-05-01

    High spectral resolution geocoronal Balmer α line profile observations from Pine Bluff Observatory (PBO) are presented in the context of forward-model analysis. Because Balmer series column emissions depend significantly on multiple scattering, retrieval of hydrogen parameters of general aeronomic interest from these observations (e.g., the hydrogen column abundance) currently requires a forward modeling approach. This capability is provided by the resonance radiative transfer code LYAO_RT. We have recently developed a parametric data-model comparison search procedure employing an extensive grid of radiative transport model input parameters (defining a 6-dimensional parameter space) to map-out bounds for feasible forward model retrieved atomic hydrogen density distributions. We applied this technique to same-night (March, 2000) ground-based Balmer α data from PBO and geocoronal Lyman β measurements from the Espectrógrafo Ultravioleta extremo para la Radiación Difusa (EURD) instrument on the Spanish satellite MINISAT-1 (provided by J.F. Gómez and C. Morales of the Laboratorio de Astrofisica Espacial y Física Fundamental, INTA, Madrid, Spain) in order to investigate the modeling constraints imposed by two sets of independent geocoronal intensity measurements, both of which rely on astronomical calibration methods. In this poster we explore extending this analysis to the line profile information also contained in the March 2000 PBO Balmer α data set. In general, a decrease in the Doppler width of the Balmer α emission with shadow altitude is a persistent feature in every night of PBO observations in which a wide range of shadow altitudes are observed. Preliminary applications of the LYAO_RT code, which includes the ability to output Doppler line profiles for both the singly and multiply scattered contributions to the Balmer α emission line, displays good qualitative agreement with regard to geocoronal Doppler width trends observed from PBO. Model-data Balmer

  4. 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.

  5. Winds from T Tauri stars. II - Balmer line profiles for inner disk winds

    NASA Technical Reports Server (NTRS)

    Calvet, Nuria; Hartmann, Lee; Hewett, Robert

    1992-01-01

    Results are presented of calculations of Balmer emission line profiles using escape probability methods for T Tauri wind models with nonspherically symmetric geometry. The wind is assumed to originate in the inner regions of an accretion disk surrounding the T Tauri star, and flows outward in a 'cone' geometry. Two types of wind models are considered, both with monotonically increasing expansion velocities as a function of radial distance. For flows with large turbulent velocities, such as the HF Alfven wave-driven wind models, the effect of cone geometry is to increase the blue wing emission, and to move the absorption reversal close to line center. Line profiles for a wind model rotating with the same angular velocity as the inner disk are also calculated. The Balmer lines of this model are significantly broader than observed in most objects, suggesting that the observed emission lines do not arise in a region rotating at Keplerian velocity.

  6. 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.

  7. X-ray Spectroscopy of the most extreme Balmer-line disk-emission AGN

    NASA Astrophysics Data System (ADS)

    Eracleous, Michael

    2005-10-01

    We propose to obtain simultaneous X-ray and UV observations of the most extreme AGN with double-peaked Balmer emission lines (FWHM > 19000km/s). We will use the XMM-Newton data to measure their X-ray spectral shapes and construct spectral energy distributions. We will combine these with measurements of the optical emission line profiles (from simultaneous HET observations) and luminosities to (a) test models for illumination of the outer disk by the central X-ray source, (b) test models for the structure of the inner accretion disk (radiatively inefficient accretion vs. standard disk), and (c) compare the X-ray-to-optical properties of these broadest Balmer-line objects to those of broad and narrow line AGN to test models for the origin of the low-ionization broad lines.

  8. Cathode sheath and hydrogen Balmer lines modelling in a micro-hollow gas discharge

    NASA Astrophysics Data System (ADS)

    Spasojević, Dj

    2012-11-01

    We present a model of the cathode sheath (CS) processes responsible for the broadening of the hydrogen Balmer beta line recorded from a micro-hollow gas discharge (MHGD) and used for simultaneous diagnostics of plasma and CS parameters. The MHGD was generated in a microhole (diameter 100 μm at narrow side and 130 μm at wider side) of a gold-alumina-gold sandwich in the pressure ranges: (100-900) mbar in argon with traces of hydrogen, and (100-400) mbar in pure hydrogen. The electron number density is determined from the plasma broadened line width of the central part of Balmer beta profile, while the average value of electric field strength in the CS and the CS thickness are determined from the extended line wings induced by the dc Stark effect.

  9. First Performance Results of a New Geocoronal Balmer-alpha Field-Widened Spatial Heterodyne Spectrometer

    NASA Astrophysics Data System (ADS)

    Gardner, D.; Mierkiewicz, E. J.; Roesler, F. L.; Harlander, J.; Jaehnig, K.; Nossal, S. M.; Haffner, L. M.

    2015-12-01

    During 2013, a new, high resolution field-widened spatial heterodyne spectrometer (FW-SHS) uniquely designed to observe geocoronal Balmer-alpha emission ([Ha], 6563A) was installed at Pine Bluff Observatory (PBO) near Madison Wisconsin. FW-SHS observations were compared with an already well-characterized dual-etalon Fabry Perot Interferometer (FPI) optimized for [Ha], also at PBO. The FW-SHS is a robust new Fourier-transform instrument that combines a large throughput advantage with high spectral resolution and a relatively long spectral baseline (~10x that of the FPI) in a compact, versatile instrument with no moving parts. Coincident [Ha] observations by FW-SHS and FPI were obtained over similar integration times, resolving power (~80,000 at [Ha]) and field-of-view (1.8 and 1.4 degrees, respectively). This paper describes the FW-SHS first light performance and [Ha] observational results collected from observing nights across 2013 and 2014. Initial FW-SHS observations of Balmer-alpha intensity and temperature (doppler width) vs. viewing geometry (shadow altitude) show excellent relative agreement with the geocoronal observations previously obtained at PBO by FPI. The FW-SHS is capable of determining geocoronal Balmer-alpha doppler shifts on the order of 100 m/s across a 640km/s [Ha] spectral bandpass, with a temporal resolution on the order of minutes. These characteristics make the FW-SHS well suited for spectroscopic studies of relatively faint, diffuse-source geocoronal Balmer-alpha emission from Earth's upper atmosphere (~2-14R) and the interstellar medium in our Galaxy. Current and future observations expand long-term geocoronal hydrogen observation data sets already spanning two solar maximums.

  10. Effect of inelastic electron-atom collisions on the Balmer decrement

    NASA Technical Reports Server (NTRS)

    Adams, W. M.; Petrosian, V.

    1974-01-01

    Calculation of the Balmer decrement in radiatively ionized hydrogen gas as a function of temperature and density, taking into account the effect of electron-atom collisions. It is found that once the electron density exceeds 10 to the 10th power per cu cm significant deviations from the normal radiative recombination decrement begin to occur. Implications of these results for the physical conditions in the line-emitting region of the Seyfert galaxy NGC 4151 are discussed briefly.

  11. 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.

  12. 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.

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

    NASA Astrophysics Data System (ADS)

    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 spectroscopy. 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 1017/sq cm at one end to approximately 140 km/s and 8 x 1017/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 1018 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 cavity is about 0

  14. Cross-sections for Balmer-alpha excitation in heavy-particle collisions

    SciTech Connect

    Bae, Y.K.

    1982-08-01

    Doppler shifted and unshifted Balmer-alpha radiation has been observed in the absolute sense for energetic H/sup +/, H/sub 2//sup +/ and H/sub 3//sup +/ ions incident on molecular hydrogen by the method of decay inside the target within the energy range of 20 keV to 150 keV. Most of the measurements were based on single-collision conditions, but a simple thick-target experiment has been tried for the case of dissociative excitation of the target molecules by H atoms.

  15. Aperture corrections for disk galaxy properties derived from the CALIFA survey. Balmer emission lines in spiral galaxies

    NASA Astrophysics Data System (ADS)

    Iglesias-Páramo, J.; Vílchez, J. M.; Galbany, L.; Sánchez, S. F.; Rosales-Ortega, F. F.; Mast, D.; García-Benito, R.; Husemann, B.; Aguerri, J. A. L.; Alves, J.; Bekeraité, S.; Bland-Hawthorn, J.; Catalán-Torrecilla, C.; de Amorim, A. L.; de Lorenzo-Cáceres, A.; Ellis, S.; Falcón-Barroso, J.; Flores, H.; Florido, E.; Gallazzi, A.; Gomes, J. M.; González Delgado, R. M.; Haines, T.; Hernández-Fernández, J. D.; Kehrig, C.; López-Sánchez, A. R.; Lyubenova, M.; Marino, R. A.; Mollá, M.; Monreal-Ibero, A.; Mourão, A.; Papaderos, P.; Rodrigues, M.; Sánchez-Blázquez, P.; Spekkens, K.; Stanishev, V.; van de Ven, G.; Walcher, C. J.; Wisotzki, L.; Zibetti, S.; Ziegler, B.

    2013-05-01

    This work investigates the effect of the aperture size on derived galaxy properties for which we have spatially-resolved optical spectra. We focus on some indicators of star formation activity and dust attenuation for spiral galaxies that have been widely used in previous work on galaxy evolution. We investigated 104 spiral galaxies from the CALIFA survey for which 2D spectroscopy with complete spatial coverage is available. From the 3D cubes we derived growth curves of the most conspicuous Balmer emission lines (Hα, Hβ) for circular apertures of different radii centered at the galaxy's nucleus after removing the underlying stellar continuum. We find that the Hα flux (f(Hα)) growth curve follows a well-defined sequence with aperture radius that shows a low dispersion around the median value. From this analysis, we derived aperture corrections for galaxies in different magnitude and redshift intervals. Once stellar absorption is properly accounted for, the f(Hα)/f(Hβ) ratio growth curve shows a smooth decline, pointing toward the absence of differential dust attenuation as a function of radius. Aperture corrections as a function of the radius are provided in the interval [0.3, 2.5]R50. Finally, the Hα equivalent-width (EW(Hα)) growth curve increases with the size of the aperture and shows a very high dispersion for small apertures. This prevents us from using reliable aperture corrections for this quantity. In addition, this result suggests that separating star-forming and quiescent galaxies based on observed EW(Hα) through small apertures will probably result in low EW(Hα) star-forming galaxies begin classified as quiescent.

  16. 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.

  17. Electron density determination in the divertor volume of ASDEX Upgrade via Stark broadening of the Balmer lines

    NASA Astrophysics Data System (ADS)

    Potzel, S.; Dux, R.; Müller, H. W.; Scarabosio, A.; Wischmeier, M.; ASDEX Upgrade Team

    2014-02-01

    In this article we present the development of a new diagnostic capable of determining the electron density in the divertor volume of ASDEX Upgrade (AUG). It is based on the spectroscopic measurement of the Stark broadening of the Balmer lines. In this work two approaches of calculating the Stark broadening, i.e. the unified theory and the model microfield method, are compared. It will be shown that both approaches yield similar results in the case of Balmer lines with high upper principal quantum numbers n. In addition, for typical AUG parameters the influence of the Zeeman splitting on the high n Balmer lines is found to be negligible. Moreover, an assumption for the Doppler broadening of Tn = 5 eV, which is the maximum Frank-Condon dissociation energy of recycled neutrals, is sufficient. The initial electron density measurements performed using this method are found to be consistent with both Langmuir probe and pressure gauge data.

  18. Excitation mechanism of hydrogen Balmer lines in a fast plasma-mixing device

    NASA Astrophysics Data System (ADS)

    Kirkici, Hulya

    1995-06-01

    The emission of hydrogen Balmer series and the laser oscillation of Hβ at 486.12 nm and Hγ at 434.06 nm in hydrogen-neon discharge operated in a pulsed mode have been reported by Dezenber and Willett [IEEE J. Quantum Electron. QE-7, 491 (1971)]. In their work, a ``two step'' excitation of molecular hydrogen to molecular ionic states, followed by dissociation of hydrogen to excited atomic species, was proposed as the main excitation mechanism. The present work was conducted to study the excitation mechanism of the hydrogen Hα line at 656.28 nm in a flowing, afterglow plasma, by using a crossed-beam plasma-mixing device. It was found that the excitation of the Hα line in this device is due to a direct dissociative energy transfer from neon metastables to molecular hydrogen.

  19. 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.

  20. 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.

  1. Estudio observacional de la segunda discontinuidad de Balmer en estrellas Be

    NASA Astrophysics Data System (ADS)

    Cochetti, Y. R.; Arias, M. L.; Cidale, L.; Zorec, J.

    Many Be stars show a second Balmer discontinuity (BD) which is related to the physical properties of their circumstellar envelopes. In this work we analize the presence and appearance (emission or absorption) of this BD in a sample of Be stars. We observe that the second BD is found in absorption among fast rotating mid- and late-B type stars while there is a tendency to observe it in emission among the hottest stars for any value of . This result suggests that the circumstellar envelopes emission volume of the latter group is larger and that the scale height of the disk could be higher than one expected from Keplerian rotation. FULL TEXT IN SPANISH

  2. Anomalous Broadening of Balmer H{sub {alpha}} Line in Aluminum and Copper Hollow Cathode Glow Discharges

    SciTech Connect

    Sisovic, N. M.; Majstorovic, G. Lj.; Konjevic, N.

    2008-10-22

    The presented results are concerned with the shape of Balmer alpha line emitted from a low pressure DC glow discharge with aluminum (Al) and copper (Cu) hollow cathode (HC) in pure H{sub 2} and Ar-H{sub 2} gas mixture. The analysis indicates that the line profile represents a convolution of Gaussian profiles resulting from different collision excitation processes.

  3. 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…

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

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

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

  5. 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.

  6. PROJECT VeSElkA: ANALYSIS OF BALMER LINE PROFILES OF SLOWLY ROTATING CHEMICALLY PECULIAR STARS

    SciTech Connect

    Khalack, V.; LeBlanc, F.

    2015-07-15

    We present results for the estimation of gravity, effective temperature, and radial velocity of poorly studied chemically peculiar stars recently observed with the spectropolarimeter Echelle SpectroPolarimetric Device for Observations of Stars at the Canada–France–Hawaii Telescope in the frame of the Vertical Stratification of Element Abundances project. The effective temperature and surface gravity values are determined for the very first time for four of the stars from our sample (HD 23878, HD 83373, HD 95608, and HD 164584). Grids of stellar atmosphere models with the corresponding fluxes have been calculated using version 15 of the PHOENIX code for effective temperatures in the range of 5000–15,000 K, for the logarithm of surface gravities in the range of 3.0–4.5 and for the metallicities from −1.0 to +1.5. We used these fluxes to fit the Balmer line profiles employing the code FITSB2 that produces estimates of the effective temperature, gravity, and radial velocity for each star. When possible, our results are compared to those previously published. The physical characteristics of 16 program stars are discussed with the future aim to study the abundance anomalies of chemical species and the possible vertical abundance stratification in their stellar atmosphere.

  7. Some regularities in the variation of the Balmer line profiles in the P CYG spectrum

    NASA Astrophysics Data System (ADS)

    Markova, N. St.

    1986-06-01

    Using the Coude focus of the 2 m RCC telescope at the National Astronomical Observatory of the Bulgarian Academy of Science, 47 spectrograms covering the range from 3500 to 4900 A (about 1400 A) with a reciprocal dispersion of 9 a/mm and a spectral resolution of 0.18 A were obtained. The photometric and position behavior of Balmer lines were investigated over a long time-scale, i.e., March 1981 to August 1982. The hydrogen line profiles were rectified in the way described by de Grot (1969). It is found that the absorption consists of three and sometimes four components. Their position behavior may be explained by the existence of two kinds of shells, pulsating and steadily expanding, and it is quite possible that shells of the first type may become shells of the second type in the outer parts of the P Cyg envelope. The total emission and absorption equivalent widths of the H11, H9, and H-delta lines change with conspicuous minima and maxima. The amplitude of these variations increases with decrease in the upper quantum number. For example, the total absorption equivalent widths change by about 38 percent for H-delta and 22 percent for H9. The data suggest a periodic change in the radial velocities, intensity of each separate absorption component, total equivalent widths and profiles.

  8. Analysis of neutral hydrogenic emission spectra in a tokamak

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  9. Secular variability of the geocoronal Balmer-alpha brightness: magnetic activity and possible human influences

    NASA Astrophysics Data System (ADS)

    Kerr, R. B.; Garcia, R.; He, X.; Noto, J.; Lancaster, R. S.; Tepley, C. A.; González, S. A.; Friedman, J.; Doe, R. A.; Lappen, M.; McCormack, B.

    2001-12-01

    Measurements of the geocoronal Balmer-alpha (Hα) brightness taken between 1983 and 1994 at the Arecibo Observatory (18.35°N, 66.75°W) occasionally display aperiodic brightness variations that we attribute to a local response of exospheric hydrogen abundance to geomagnetic activity. Approximately twofold Hα brightness enhancements in the days following moderate storm onset conditions are demonstrated, and the absolute brightness during these events is significantly greater than modeled brightness based on quiet geomagnetic conditions. Although there are no direct measurements of the line center solar Lyman beta (Ly β) flux that pumps Hα during these events, the magnitude of the brightness enhancements and the temporal reproducibility of the phenomena (following onset of all storms in our data) make it likely that the enhanced Hα brightness is due to enhanced column abundances of hydrogen in the exosphere above Arecibo and not to sporadic increases in the solar Ly β flux. Increased hydrogen abundance due to thermal expansion of the midlatitude atmosphere following propagation of the auroral heating event cannot account for the entire enhancement. The data also suggest that Hα brightness has become systematically stronger from 1984 to 1994, independent of solar cycle variability or variations due to geomagnetic activity. An increase of ~3% per year, may be attributable to real change in the geocoronal hydrogen column abundance during the period, and is possibly a consequence of increasing hydrogenous species concentrations in the lower atmosphere. The enhancement of geocoronal Hα brightness between 1984 and 1994 may be the consequence of increasing methane in the troposphere and may signal that the effects of methane deposition in the lower atmosphere have propagated throughout the atmosphere.

  10. 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

  11. 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.

  12. Time-resolved EUV spectra from nitrogen Z-pinching capillary discharge

    NASA Astrophysics Data System (ADS)

    Nevrkla, Michal; Jančárek, Alexandr; Nawaz, Fahad; Parkman, Tomáś; Vrbová, Miroslava

    2015-05-01

    Time-integrated spectra and time-resolved spectra (20 ns resolution) of nitrogen discharge plasma radiation were recorded and analyzed. Plasma was created by a 70 kA, 29 ns rise-time current pulse flowing through a 5 mm inner diameter, 224 mm long capillary filled with nitrogen to initial pressure ˜0.1 ÷ 1 kPa. 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 transition1. Spectral lines were identified using the NIST database and the FLY kinetic code. Together with spectra the capillary current was measured. Due to the low inductance design of the driver, the pinch is observable directly from the measured current. 13.38 nm NVII 2 - 3 line was observed in gated, and also in time-integrated spectra for currents <60 kA. For higher gas-filling pressure also other Balmer series lines were observed.

  13. IUE and Optical Spectra of AL Comae Berenices During a Rare Superoutburst

    NASA Astrophysics Data System (ADS)

    Szkody, Paula; Silber, Andrew; Sion, Ed; Downes, Ronald A.; Howell, Steve B.; Costa, Edgardo; Moreno, H.

    1996-06-01

    We present optical spectra from 3 to 21 days and lUE spectra at 10 and 19 days following the outburst of the extreme amplitude, very short orbital period cataclysmic variable AL Corn after a 20 yr quiescent interval. The lUE spectra have no evidence of P Cyg profiles and show an early presence of Lyα absorption, which may be indicative of a 25,000 K white dwarf. The optical spectra show only weak Balmer absorption throughout this interval, with no dramatic changes within the 3 weeks. The spectra are compared to those available for the few other systems that had similar long outbursts following a long quiescence (WZ Sge, WX Cet, SW UMa).

  14. 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.

  15. 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.

  16. 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.

  17. Hydrogen Balmer beta: The separation between line peaks for plasma electron density diagnostics and self-absorption test

    NASA Astrophysics Data System (ADS)

    Ivković, Milivoje; Konjević, Nikola; Pavlović, Zoran

    2015-03-01

    We propose a diagnostic technique for the measurement of plasma electron number density, Ne, based on the wavelength separation between peaks, ΔλPS, of hydrogen Balmer beta line, Hβ. In favor of the proposed diagnostic technique we demonstrate high sensitivity of ΔλPS on Ne and low sensitivity on plasma elementary processes and plasma parameters that may distort the line profile. These properties of ΔλPS enable reliable Ne plasma diagnostics in the presence of considerable self-absorption. On the basis of available theoretical data tables for the Hβ line profiles, simple Ne=f(ΔλPS) formulas are proposed. Their validity is experimentally confirmed in a low initial pressure pulsed discharge for the Ne range of (0.2-7)*1023 m-3. The agreement of the proposed formulas with another diagnostic technique is well within 10%. In addition, the difference in Ne values obtained from peak separation and from the Hβ line width is successfully used as a self-absorption test for line profile.

  18. 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.

  19. 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).

  20. 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.

  1. 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}⊙ )≃ 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.

  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. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. A method of interpreting the Balmer-alpha high-resolution spectroscopy for tokamak edge plasmas with account of divertor stray light

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

    A method is suggested for interpreting the data from the Balmer-alpha high- resolution spectroscopy diagnostics of the edge plasma in the tokamak main chamber, which additionally uses the data from direct observation of the divertor. Such an extension of the diagnostics is motivated by the fact that in a tokamak-reactor with the metal first wall, like ITER tokamak, a significant role of the divertor stray light (DSL), which is emitted by the plasma in the divertor in the same spectral line and reflected from the first wall of the vacuum chamber to a spectrometer in the main chamber, is expected. The results of the first applications of the developed model to interpret the data from the JET-ILW tokamak experiments, which simulate the conditions of occurrence of the DSL in ITER, are discussed.

  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. Observation of beam-induced changes in the polarization of Balmer-{alpha} radiation emitted following beam--tilted-foil transmission

    SciTech Connect

    Harper, D.L.; Albridge, R.G.; Tolk, N.H.; Qi, W.; Allred, D.D.; Knight, L.V.

    1995-12-01

    Measurements of the circular polarization of Balmer-{alpha} radiation emitted by excited hydrogen atoms, following the transmission of (20--50)-keV protons through thin, tilted amorphous carbon foils, exhibit markedly unexpected behavior as a function of exposure of the foil to the proton beam. Specifically, the circular polarization changes from an initially well understood tilt-angle dependence to a behavior which, for low tilt angles, gives the {ital opposite} {ital handedness} {ital of} {ital circular} {ital polarization} from that predicted. In addition, the degree of alignment, indicated by the linear Stokes parameter {ital M}/{ital I}, is enhanced also as a function of dose. These changes in the tilt-angle dependence of the Stokes parameters have been systematically correlated with beam-induced graphitization of the foil, which is observed to occur from Raman measurements.

  13. 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)

  14. [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

  15. [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.

  16. 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.

  17. Spectra of stable sonoluminescence

    NASA Astrophysics Data System (ADS)

    Lewis, Stephen D.

    1992-12-01

    The continuous emission of picosecond pulses of light has been observed to originate from a bubble trapped at the pressure antinode of a resonant sound field in water and in water/glycerin mixtures. The spectra of this light in several solutions has been measured with a scanning monochrometer/photomultiplier detector system. The spectra are broadband and show strong emission in the UV region. A comparison of this measurement to two other independently produced spectra is made. The spectra are also modeled by a blackbody radiation distribution to determine an effective blackbody temperature and a size is deduced as if Sonoluminescence were characterized by blackbody radiation.

  18. 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.

  19. 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).

  20. 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.

  1. Polarization of Lyman-α and Balmer-α emission in proton-hydrogen collisions: a study using first-order Born-Faddeev-type equations

    NASA Astrophysics Data System (ADS)

    Fathi, R.; Bolorizadeh, M. A.; Shojaei Akbarabadi, F.; Brunger, M. J.

    2012-10-01

    A three-body Born-Faddeev model is devised to calculate the total cross sections of Balmer-α and Lyman-α emissions, for the excitation of hydrogen atoms by proton impact in the energy range of 100 keV-7 MeV. In addition, the polarization alignment factor A20 is calculated and compared against available experimental data to further test the theory. Specifically, here we use the Faddeev-Watson-Lovelace formalism to study the excitation of atomic hydrogen from its ground state to the excited states of n = 2 and 3 and magnetic sublevels l = 0, 1 and 2, wherever applicable. The first-order electronic, A(1)e, and the first-order nuclear, A(1)n, amplitudes are considered in order to calculate the excitation transition matrix (TPT), while a near-the-shell condition is assumed throughout. In addition, our results were used to calculate the first-order form factors. The present results are compared, where possible, with those of other theoretical and experimental works that are currently available in the literature.

  2. 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

  3. Lily Pad Spectra

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The color image on the lower left from the panoramic camera on the Mars Exploration Rover Opportunity shows the 'Lily Pad' bounce-mark area at Meridiani Planum, Mars. This image was acquired on the 3rd sol, or martian day, of Opportunity's mission (Jan.26, 2004). The upper left image is a monochrome (single filter) image from the rover's panoramic camera, showing regions from which spectra were extracted from the 'Lily Pad' area. As noted by the line graph on the right, the green spectra is from the undisturbed surface and the red spectra is from the airbag bounce mark.

  4. 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.

  5. Reddening and age for 13 southern Galactic open clusters determined from integrated spectra

    NASA Astrophysics Data System (ADS)

    Ahumada, A. V.; Clariá, J. J.; Bica, E.; Dutra, C. M.; Torres, M. C.

    2001-10-01

    In this study we present flux-calibrated integrated spectra in the range 3800-6800 Å for 13 concentrated open clusters with Galactic longitudes between 219deg and 316deg, nine of which have not been previously studied. Using the equivalent widths of the Balmer lines and comparing the cluster spectra with template spectra of Magellanic Clouds and Galactic star clusters with known parameters, we derive both foreground interstellar reddening values and age. For nine clusters these two parameters have been determined for the first time, while for the rest of the sample the results show good agreement with previous studies. The present analysis indicates four very young (Hogg 11, NGC 5606, vdB-RN 80 and Pismis 17), seven moderately young (ESO 429-SC13, Hogg 3, Hogg 12, Haffner 7, BH 87, NGC 2368 and Bochum 12) and two intermediate-age (Berkeley 75 and NGC 2635) open clusters. The derived foreground interstellar reddening values are in the range 0.00 <= E(B-V) <= 0.38. The age and reddening distributions of the present sample of relatively faint open clusters match those of open clusters with known parameters in a 90deg sector centered at l = 270deg. Based on observations made at Complejo Astronómico El Leoncito, which is operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba and San Juan, Argentina.

  6. 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.

  7. 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.

  8. Rock Outcrop Spectra

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The color image on the lower left shows a rock outcrop at Meridiani Planum, Mars. This image was taken by the panoramic camera on the Mars Exploration Rover Opportunity, looking north, and was acquired on the 4th sol, or martian day, of the rover's mission (Jan. 27, 2004). The yellow box outlines an area detailed in the top left image, which is a monochrome (single filter) image from the rover's panoramic camera. The top image uses solid colors to show several regions on or near the rock outcrop from which spectra were extracted: the dark soil above the outcrop (yellow), the distant horizon surface (aqua), a bright rock in the outcrop (green), a darker rock in the outcrop (red), and a small dark cobblestone (blue). Spectra from these regions are shown in the plot to the right.

  9. 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.

  10. 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.

  11. IUE archived spectra

    NASA Technical Reports Server (NTRS)

    Sullivan, Edward C.; Bohlin, Ralph C.; Heap, Sara R.; West, Donald K.; Schmitz, Marion

    1988-01-01

    The International Ultraviolet Explorer (IUE) Satellite has been in continuous operation since January 26, 1978. To date, approximately 65,000 spectra have been stored in an archive at Goddard Space Flight Center in Greenbelt, MD. A number of procedures have been generated to facilitate access to the data in the IUE spectral archive. This document describes the procedures which include on-line quick look of the displays, search of an observation data base for selected observations, and several methods for ordering data from the archive.

  12. Meteors and meteorites spectra

    NASA Astrophysics Data System (ADS)

    Koukal, J.; Srba, J.; Gorková, S.; Lenža, L.; Ferus, M.; Civiš, S.; Knížek, A.; Kubelík, P.; Kaiserová, T.; Váňa, P.

    2016-01-01

    The main goal of our meteor spectroscopy project is to better understand the physical and chemical properties of meteoroids. Astrometric and spectral observations of real meteors are obtained via spectroscopic CCD video systems. Processed meteor data are inserted to the EDMOND database (European viDeo MeteOr Network Database) together with spectral information. The fully analyzed atmospheric trajectory, orbit and also spectra of a Leonid meteor/meteoroid captured in November 2015 are presented as an example. At the same time, our target is the systematization of spectroscopic emission lines for the comparative analysis of meteor spectra. Meteoroid plasma was simulated in a laboratory by laser ablation of meteorites samples using an (ArF) excimer laser and the LIDB (Laser Induced Dielectric Breakdown) in a low pressure atmosphere and various gases. The induced plasma emissions were simultaneously observed with the Echelle Spectrograph and the same CCD video spectral camera as used for real meteor registration. Measurements and analysis results for few selected meteorite samples are presented and discussed.

  13. 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.

  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. Interpreting Chromosome Aberration Spectra

    NASA Technical Reports Server (NTRS)

    Levy, Dan; Reeder, Christopher; Loucas, Bradford; Hlatky, Lynn; Chen, Allen; Cornforth, Michael; Sachs, Rainer

    2007-01-01

    Ionizing radiation can damage cells by breaking both strands of DNA in multiple locations, essentially cutting chromosomes into pieces. The cell has enzymatic mechanisms to repair such breaks; however, these mechanisms are imperfect and, in an exchange process, may produce a large-scale rearrangement of the genome, called a chromosome aberration. Chromosome aberrations are important in killing cells, during carcinogenesis, in characterizing repair/misrepair pathways, in retrospective radiation biodosimetry, and in a number of other ways. DNA staining techniques such as mFISH ( multicolor fluorescent in situ hybridization) provide a means for analyzing aberration spectra by examining observed final patterns. Unfortunately, an mFISH observed final pattern often does not uniquely determine the underlying exchange process. Further, resolution limitations in the painting protocol sometimes lead to apparently incomplete final patterns. We here describe an algorithm for systematically finding exchange processes consistent with any observed final pattern. This algorithm uses aberration multigraphs, a mathematical formalism that links the various aspects of aberration formation. By applying a measure to the space of consistent multigraphs, we will show how to generate model-specific distributions of aberration processes from mFISH experimental data. The approach is implemented by software freely available over the internet. As a sample application, we apply these algorithms to an aberration data set, obtaining a distribution of exchange cycle sizes, which serves to measure aberration complexity. Estimating complexity, in turn, helps indicate how damaging the aberrations are and may facilitate identification of radiation type in retrospective biodosimetry.

  16. Sequencing BPS spectra

    DOE PAGES

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

    2016-03-02

    In this article, we provide 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 explainmore » 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 Poincar e polynomials in numerous examples. Among these structural properties is a novel "sliding" property, which can be explained by using (re fined) modular S-matrix. This leads to the identi fication of modular transformations in Chern-Simons theory and 3d N = 2 theory via the 3d/3d correspondence. In conclusion, we introduce the notion of associated varieties as classical limits of recursion relations of colored superpolynomials of links, and study their properties.« less

  17. 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.

  18. [EPR spectra of silkworm eggs].

    PubMed

    Korkhova, E D; Chepel', L M; Nikolov, O T; Komar', I N; Shakhbazov, V G

    1976-01-01

    ESR spectra of the native grain of the silkworm have been studied in the course of embryo formation, during a diapause, and during embryo development after the diapause. It is shown that the nature of ESR spectra of the grain is not determined by the metabolic processes, but by the presence of pigments in it and other stationary biological structures having developed pi-systems and unpaired electrones. The latter are mainly found in the envelope and may give the ESR spectra, with various g-factors. A dependence of the ESR spectra integral intensity of the grain on the denotype is discovered.

  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. 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.

  2. 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

  3. Measurement and analysis of atomic hydrogen and diatomic molecular AlO, C2, CN, and TiO spectra following laser-induced optical breakdown.

    PubMed

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

    2014-02-14

    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.

  4. 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

  5. Complex Spectra in Fusion Plasmas

    NASA Astrophysics Data System (ADS)

    von Hellermann, M. G.; Bertschinger, G.; Biel, W.; Giroud, C.; Jaspers, R.; Jupen, C.; Marchuk, O.; O'Mullane, M.; Summers, H. P.; Whiteford, A.; Zastrow, K.-D.

    2005-01-01

    The need for quantitative evaluation of complex line emission spectra as observed in hot fusion plasmas initiated a challenging development of sophisticated interpretation tools based on integrating advanced atomic modelling with detailed treatment of the plasma environment. The successful merging of the two worlds has led to routine diagnostic procedures which have contributed enormously to the understanding of underlying plasma processes and also to a wide acceptance of spectroscopy as a reliable diagnostic method. In this paper three characteristic types of spectra of current and continuing interest are presented. The first is that of medium/heavy species with many ionisation stages revealed in survey VUV and XUV spectra. Such species occur as control gases, as wall materials, as ablated heavy species and possible as layered wall dopants for monitoring erosion. The spectra are complex with line-like and quasi-continuum regions and are amenable to advanced `pattern recognition' methods. The second type is of few electron, highly ionised systems observed as line-of-sight integrated passive emission spectra in the soft x-ray region. They are analysed successfully in terms of plasma parameters through matching of observation with predicted synthetic spectra. Examples used here include highly resolved helium-like emission spectra of argon, iron and titanium observed on the tokamaks TEXTOR and Tore Supra. The third type, and the emphasis of this work, comprises spectra linked to active beam spectroscopy, that is, charge exchange recombination spectroscopy (CXRS) and beam emission spectroscopy (BES). In this case, a complex spectrum is again composed of a (usually) dominating active spectrum and an underlying passive emission spectrum. Its analysis requires modelling of both active and passive features. Examples used here are from the CXRS diagnostic at JET and TEXTOR. They display characteristic features of the main light impurity ions (C+6, He+2, N+7, Ne+10 and Ar+18

  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. Reduction of multielement mass spectra

    SciTech Connect

    Russ, G.P. III; Caffee, M.W.; Hudson, G.B.; Storch, N.A.

    1990-06-29

    Even though the spectra obtained by inductively coupled plasma source spectrometry (ICP-MS) are relatively simple, their interpretation can be complicated by the presence of molecular and isobaric interferants. To the extent that isotopic abundances are known and constant, one can treat observed spectra as sums of known components. A linear decomposition approach for determining the concentrations of the components in a spectrum and correctly propagating uncertainties is presented. This technique differs from linear regression in that an exact fit is made to a subset of isotopes and goodness-of-fit is evaluated from the deviations between the predicted and measured intensities of the other, unfit isotopes. This technique can be applied to a wide range of spectral fitting problems. In this paper, its applicability to ICP-MS spectra is used to demonstrate the use and utility of the technique. 2 refs., 9 figs.

  8. 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.

  9. 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.

  10. 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.

  11. The structure of BPS spectra

    NASA Astrophysics Data System (ADS)

    Longhi, Pietro

    In this thesis we develop and apply novel techniques for analyzing BPS spectra of supersymmetric quantum field theories of class S. By a combination of wall-crossing, spectral networks and quiver methods we explore the BPS spectra of higher rank four-dimensional N = 2 super Yang-Mills, uncovering surprising new phenomena. Focusing on the SU(3) case, we prove the existence of wild BPS spectra in field theory, featuring BPS states of higher spin whose degeneracies grow exponentially with the energy. The occurrence of wild BPS states is surprising because it appears to be in tension with physical expectations on the behavior of the entropy as a function of the energy scale. The solution to this puzzle comes from realizing that the size of wild BPS states grows rapidly with their mass, and carefully analyzing the volume-dependence of the entropy of BPS states. We also find some interesting structures underlying wild BPS spectra, such as a Regge-like relation between the maximal spin of a BPS multiplet and the square of its mass, and the existence of a universal asymptotic distribution of spin-j irreps within a multiplet of given charge. We also extend the spectral networks construction by introducing a refinement in the topological classification of 2d-4d BPS states, and identifying their spin with a topological invariant known as the "writhe of soliton paths". A careful analysis of the 2d-4d wall-crossing behavior of this refined data reveals that it is described by motivic Kontsevich-Soibelman transformations, controlled by the Protected Spin Character, a protected deformation of the BPS index encoding the spin of BPS states. Our construction opens the way for the systematic study of refined BPS spectra in class S theories. We apply it to several examples, including ones featuring wild BPS spectra, where we find an interesting relation between spectral networks and certain functional equations. For class S theories of A 1 type, we derive an alternative technique for

  12. cloud supersaturations and CCN spectra

    NASA Astrophysics Data System (ADS)

    Hudson, James; Noble, Stephen

    2014-05-01

    Multiple regression analysis predictions of low altitude cloud droplet concentrations based on measured CCN spectra compared much better with measured low altitude droplet concentrations than various CCN concentrations at single supersaturations (S) in two aircraft cumulus cloud projects, RICO and ICE-T. The addition of vertical velocity (W) to the single and multiple regressions showed small improvements. For RICO the multiple regression correlations were also superior to previous adiabatic model predictions of droplet concentrations also based on CCN spectra and mean W. More adiabatic cloud parcels showed only slightly better correlations than flight-averaged droplet concentrations. Results show the value of more extensive CCN spectra and the relative unimportance of W variations for determining droplet concentrations in these Caribbean cumuli. The fact that flight-averaged droplet concentrations of all low cloud data was almost as well correlated with CCN spectra as were droplet concentrations of more adiabatic cloud parcels indicates that entrainment did not significantly perturb CCN-droplet concentration relationships. As should be expected higher cloud S were determined for the cumulus clouds than for stratus clouds. Suppression of cloud S by higher CCN concentrations that had previously been observed in stratus was observed in ICE-T but not in RICO where the CCN range may have been too low for cloud S suppression. But ICE-T and a stratus project, POST, even showed this S suppression over the same limited maritime CCN range as RICO.

  13. Classical Trajectories and Quantum Spectra

    NASA Technical Reports Server (NTRS)

    Mielnik, Bogdan; Reyes, Marco A.

    1996-01-01

    A classical model of the Schrodinger's wave packet is considered. The problem of finding the energy levels corresponds to a classical manipulation game. It leads to an approximate but non-perturbative method of finding the eigenvalues, exploring the bifurcations of classical trajectories. The role of squeezing turns out decisive in the generation of the discrete spectra.

  14. Shape effects on asteroid spectra

    NASA Astrophysics Data System (ADS)

    Davalos, J.; Carvano, J.

    2014-07-01

    The objective of this work is to probe how the shape of a body like an asteroid could be modifying its observed spectra and the derived mineralogical interfaces based on spectral modeling. To model this effect, we construct an oblate ellipsoid with triangular facets, where each facet contributes to the overall reflectance. The synthetic spectra is generated by the isotropic multiple-scattering approximation (IMSA) reflectance model of Hapke (1993). First, we obtained optical constants by inverting the spectra of meteorites, obtained from the RELAB spectral database. These optical constants were found inverting the reflectance bidirectional equation of Hapke; this is made in two steps: (i) The first inversion is to find the single-scattering albedo π (ii) in the model of Hapke, this albedo is found under the regime of the geometric optics, where the particle size is much larger than the wavelength of the incident radiation. Here we assumed a constant value for the real part of the optical constant n=1.5. With these optical constants, we can construct synthetic spectra for any particle size. The phase function used is the double Henyey-Greenstein phase function and an accurate expression for the H-functions. We started with the ellipsoidal shape a=1.0, b=c=0.5 for two particle size 50 and 250 μ m, in this part, we found good differences in the BAR parameter between the two geometric models, this was done for 100 Eucrite meteorites spectra. In this first study, we found that the BAR parameter between the two models is bigger when the particle size increases. In the second part, we started with different ellipsoidal shapes and produced synthetic spectra for material with eucrite and diogenite composition with a phase angle of 20 degrees, incidence and emission angles of 10 degrees, and particle size at 250 μ m. All spectra was generated for four parameters of phase angle b=[0.2,0.4,0.6,0.8] taking the empirical relation between the phase constants of Hapke (2012

  15. Source spectra of seismic hum

    NASA Astrophysics Data System (ADS)

    Nishida, Kiwamu

    2014-10-01

    The observation of seismic hum from 2 to 20 mHz, also known as Earth's background free oscillations, has been established. Recent observations by broad-band seismometers show simultaneous excitation of Love waves (fundamental toroidal modes) and Rayleigh waves (fundamental spheroidal modes). The excitation amplitudes above 10 mHz can be explained by random shear traction sources on Earth's surface. With estimated source distributions, the most likely excitation mechanism is a linear coupling between ocean infragravity waves and seismic surface waves through seafloor topography. Observed Love and Rayleigh wave amplitudes below 5 mHz suggest that surface pressure sources could also contribute to their excitations, although the amplitudes have large uncertainties due to the high noise levels of the horizontal components. To quantify the observation, we develop a new method for estimation of the source spectra of random tractions on Earth's surface by modelling cross-spectra between pairs of stations. The method is to calculate synthetic cross-spectra for spatially isotropic and homogeneous excitations by random shear traction and pressure sources, and invert them with the observed cross-spectra to obtain the source spectra. We applied this method to the IRIS, ORFEUS, and F-net records from 618 stations with three components of broad-band seismometers for 2004-2011. The results show the dominance of shear traction above 5 mHz, which is consistent with past studies. Below 5 mHz, however, the spectral amplitudes of the pressure sources are comparable to those of shear traction. Observed acoustic resonance between the atmosphere and the solid Earth at 3.7 and 4.4 mHz suggests that atmospheric disturbances are responsible for the surface pressure sources, although non-linear ocean wave processes are also candidates for the pressure sources. Excitation mechanisms of seismic hum should be considered as a superposition of the processes of the solid Earth, atmosphere and ocean

  16. Phobos surface spectra mineralogical modeling

    NASA Astrophysics Data System (ADS)

    Pajola, M.; Lazzarin, M.; Dalle Ore, C. M.; Cruikshank, D. P.; Roush, T. L.; Pendleton, Y.; Bertini, I.; Magrin, S.; Carli, C.; La Forgia, F.; Barbieri, C.

    2014-04-01

    A mineralogical model composed of a mixture of Tagish Lake meteorite (TL) and Pyroxene Glass (PM80) was presented in [1] to explain the surface reflectance of Phobos from 0.25 to 4.0 μm. The positive results we obtained, when comparing the OSIRIS data [2] extended in wavelength to include the [3,4] spectra, forced us to perform a wider comparison between our TL-PM80 model and the CRISM and OMEGA Phobos spectra presented in [5]. Such spectra cover three different regions of interest (ROIs) situated in the Phobos sub-Mars hemisphere: the interior of the Stickney crater, its eastern rim, and its proximity terrain southeast of the Reldresal crater. We decided to vary the percentage mixture of the components of our model (80% TL, 20% PM80), between pure TL and pure PM80, by means of the radiative transfer code based on the [6] formulation of the slab approximation. Once this spectral range was derived, see Fig. 1, we attempted to compare it with the [5] spectra between 0.4 and 2.6 μm, i.e. below the thermal emitted radiation, to see if any spectral match was possible. We observed that CRISM scaled spectra above 1.10 μm fall within pure Tagish Lake composition and the [1] model. The CRISM data below 1.10 μm present more discrepancies with our models, in particular for the Stickney's rim spectrum. Nevertheless the TL and PM80 components seem to be good mineralogical candidates on Phobos. We performed the same analysis with the OMEGA data and, again, we found out that the Stickney's rim spectrum lies out of our model range, while the two remaining spectra still lie between pure TL and 80% TL - 20% PM80, but indicating that a different, more complicated mixture is expected in order to explain properly both the spectral trend and the possible absorption bands located above 2.0 μm. Within this analysis, we point out that a big fraction of TL material (modeled pure or present with a minimum percentage of 80% mixed together with 20% PM80) seems to explain Phobos spectral

  17. Eigenvectors of optimal color spectra.

    PubMed

    Flinkman, Mika; Laamanen, Hannu; Tuomela, Jukka; Vahimaa, Pasi; Hauta-Kasari, Markku

    2013-09-01

    Principal component analysis (PCA) and weighted PCA were applied to spectra of optimal colors belonging to the outer surface of the object-color solid or to so-called MacAdam limits. The correlation matrix formed from this data is a circulant matrix whose biggest eigenvalue is simple and the corresponding eigenvector is constant. All other eigenvalues are double, and the eigenvectors can be expressed with trigonometric functions. Found trigonometric functions can be used as a general basis to reconstruct all possible smooth reflectance spectra. When the spectral data are weighted with an appropriate weight function, the essential part of the color information is compressed to the first three components and the shapes of the first three eigenvectors correspond to one achromatic response function and to two chromatic response functions, the latter corresponding approximately to Munsell opponent-hue directions 9YR-9B and 2BG-2R.

  18. 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``).

  19. 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

  20. 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.

  1. 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.

  2. Variable spectra of active galaxies

    NASA Technical Reports Server (NTRS)

    Halpern, Jules P.

    1988-01-01

    The analysis of EXOSAT spectra of active galaxies are presented. The objects examined for X-ray spectral variability were MR 2251-178 and 3C 120. The results of these investigations are described, as well as additional results on X-ray spectral variability related to EXOSAT observations of active galaxies. Additionally, the dipping X-ray source 4U1624-49 was also investigated.

  3. Near-infrared Spectra and Intrinsic Luminosities of Candidate Type II Quasars at 2 < z < 3.4

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    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-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-1. Interestingly, the C IV lines also require broad bases, but with considerably narrower widths of 1000-4500 km s-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 AV 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.

  4. 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.

  5. Theoretical prediction of vibrational spectra

    NASA Astrophysics Data System (ADS)

    Niu, Zefu; Dunn, Kevin M.; Boggs, James E.

    The complete harmonic force field and the diagonal and first off-diagonal cubic constants of aniline have been calculated ab initio using a 4-21 basis set augmented by addition of d functions to the nitrogen atom. The force constants were then scaled using scale factors optimized previously to give the best fit to the similarly computed vibrational spectra of benzene and its deuterated isotopomers. The vibrational spectra of aniline, aniline-NHD, and aniline-ND2 were then calculated from this scaled quantum mechanical (SQM) force field and compared with experimentally observed spectra. Several corrections were made to previously proposed empirical spectral assignments. Because of computational difficulties, no definitive statement can be made about the torsion or inversion modes of the amino group. Aside from these and the C-H stretching frequencies for which the detailed assignment is still quite uncertain, the average deviation between the observed frequencies and those obtained entirely from the scaled computed force field is 9·1 cm-1. Dipole moment derivatives and infrared absorption intensities were also calculated, but these are of lower accuracy.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Gamma-ray burst spectra

    NASA Technical Reports Server (NTRS)

    Teegarden, B. J.

    1982-01-01

    A review of recent results in gamma-ray burst spectroscopy is given. Particular attention is paid to the recent discovery of emission and absorption features in the burst spectra. These lines represent the strongest evidence to date that gamma-ray bursts originate on or near neutron stars. Line parameters give information on the temperature, magnetic field and possibly the gravitational potential of the neutron star. The behavior of the continuum spectrum is also discussed. A remarkably good fit to nearly all bursts is obtained with a thermal-bremsstrahlung-like continuum. Significant evolution is observed of both the continuum and line features within most events.

  13. An RGB approach to extraordinary spectra

    NASA Astrophysics Data System (ADS)

    Grusche, Sascha; Theilmann, Florian

    2015-09-01

    After Newton had explained a series of ordinary spectra and Goethe had pointed out its complementary counterpart, Nussbaumer discovered a series of extraordinary spectra which are geometrically identical and colourwise analogous to Newton’s and Goethe’s spectra. To understand the geometry and colours of extraordinary spectra, the wavelength composition is explored with filters and spectroscopic setups. Visualized in a dispersion diagram, the wavelength composition is interpreted in terms of additive colour mixing. Finally, all spectra are simulated as the superposition of red, green, and blue images that are shifted apart. This RGB approach makes it easy to understand the complex relationship between wavelengths and colours.

  14. Brane Constructions and BPS Spectra

    NASA Astrophysics Data System (ADS)

    Rastogi, Ashwin

    The object of this work is to exploit various constructions of string theory and M-theory to yield new insights into supersymmetric theories in both four and three dimensions. In 4d, we extend work on Seiberg-Witten theory to study and compute BPS spectra of the class of complete N = 2 theories. The approach we take is based on the program of geometric engineering, in which 4d theories are constructed from compactifications of type IIB strings on Calabi-Yau manifolds. In this setup, the natural candidates for BPS states are D3 branes wrapped on supersymmetric 3-cycles in the Calabi-Yau. Our study makes use of the mathematical structure of quivers, whose representation theory encodes the notion of stability of BPS particles. Except for 11 exceptional cases, all complete theories can be constructed by wrapping stacks of two M5 branes on Riemann surfaces. By exploring the connection between quivers and M5 brane theories, we develop a powerful algorithm for computing BPS spectra, and give an in-depth study of its applications. In particular, we compute BPS spectra for all asymptotically free complete theories, as well as an infinite set of conformal SU(2)k theories with certain matter content. From here, we go on to apply the insight gained from our 4d study to 3d gauge theories. We consider the analog of the M5 brane construction in the case of 3d N = 2 theories: pairs of M5 branes wrapped on a 3-manifold. Using the ansantz of R-flow, we study 3-manifolds consisting of Riemann surfaces fibered over R. When the construction is non-singular, the resulting IR physics is described by a free abelian Chern-Simons theory. The mathematical data of a tangle captures the data of the gauge theory, and the Reidemeister equivalances on tangles correspond to dualities of physical descriptions. To obtain interacting matter, we allow singularities in the construction. By extending the tangle description to these singular cases, we find a set of generalized Reidemeister moves that

  15. Pressure spectra and cross spectra at an area contraction in a ducted combustion system

    NASA Technical Reports Server (NTRS)

    Miles, J. H.; Raftopoulos, D. D.

    1980-01-01

    Pressure spectra and cross-spectra at an area contraction in a liquid fuel, ducted, combustion noise test facility are analyzed. Measurements made over a range of air and fuel flows are discussed. Measured spectra are compared with spectra calculated using a simple analytical model.

  16. 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.

  17. 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.

  18. 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}

  19. 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.

  20. 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

  1. 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

  2. Refractory sea salt CCN spectra

    NASA Astrophysics Data System (ADS)

    Noble, S.; Hudson, J. G.

    2012-12-01

    Hudson et al. (2011; H11) showed a substantial sea salt (NaCl) CCN contribution for low critical supersaturation (Sc) CCN (< 0.1%), which was a positive function of horizontal wind speed (U) at the ocean surface in the RICO project in the Caribbean. Somewhat similar results were found over the Pacific near California in spite of a factor of 3 higher average CCN concentrations. Results were obscured over the mid Pacific in PASE because of the lack of cloud scavenging (H11). The results were obtained by CCN spectral volatility measurements, which remove all but the refractory CCN that survive heating to 300 degrees C, which are only NaCl. Fig. 1 shows that ambient CCN concentrations were uncorrelated with U but that refractory CCN were correlated with U in RICO and POST. Fig. 2 compares low altitude average refractory CCN spectra during flights with various noted mean U. The two POST flights and the RICO flights displayed here show the same dependence on U that was quantified by H11. The higher concentrations for PASE in relation to U are due to the lack of cloud scavenging, which allowed higher concentrations to build up that are thus not related to the simultaneously measured U. The abundant clouds of RICO and POST provided enough removal of CCN that sea salt CCN were correlated with simultaneously measured U. These measurements have begun the quantification of this most definite natural CCN source. This is needed in order to assess the impact of anthropogenic CCN on clouds; i.e., the indirect aerosol effect. Hudson, J.G., S. Noble, and V. Jha, 2011: On the relative role of sea salt cloud condensation nuclei (CCN). J. Atmos. Chem. Volume 68, Number 1, Pages 71-88, DOI: 10.1007/s10874-011-9210-5. Fig. 1. Correlation coefficients (R) between CCN concentrations at various S and wind speed for ambient CCN (all) and refractory CCN. Fig. 2. Flight averaged refractory CCN spectra.

  3. Modelling asteroid spectra: few examples

    NASA Astrophysics Data System (ADS)

    Birlan, M.; Popescu, M.

    2011-10-01

    Asteroidal population comprises now more than 500,000 objects. Several observational techniques (spectroscopy, adaptive optics, photometry, polarimetry, radar,..) are used in order to obtain a mature understanding of an overall knowledge of this population. Spectroscopy can play a key role in determining the chemical composition and physical process that took place and modified the surface of asteroids. The development of telescopic instruments and the possibility to access them remotely allowed an increasing number of asteroid spectral measurements. The exploitation of spectral measurements is one of the important items to enlarge our science of surfaces of atmosphereless bodies. Spectral data of asteroids are in continuing growth. To exploit these spectral data we must account the global science of this population as well as the knowledge derived by studies of comparative planetology. The project M4AST (Modeling for Asteroids) consists in a database containing the results of these telescopic measurements and a set of applications for spectral analysis (Fig. 1). M4AST cover several aspects related to statistics of asteroids (taxonomy), mineralogical solutions using laboratory spectra from RELAB, and mineralogical modeling using space weathering effects corroborated with radiative transfer laws. M4AST was conceived to be available via a web interface and will be available for the scientific community. The abilities of these routines will be highlighted by few examples. Science derived via M4AST obtained for (222) Lucia, (809) Lundia, (810) Atossa, (1005) Arago, (1220) Crocus, and (4486) Mithra will be presented.

  4. 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.

  5. Band Spectra and Molecular Structure

    NASA Astrophysics Data System (ADS)

    Kronig, R. De L.

    2011-06-01

    Introduction; Part I. The Energy Levels of Diatomic Molecules and their Classification by Means of Quantum Numbers: 1. General foundations; 2. Wave mechanics of diatomic molecules; 3. Electronic levels; 4. Vibrational levels; 5. Rotational levels; 6. Stark and Zeeman effect; 7. Energy levels of polyatomic molecules; Part II. Fine Structure and Wave Mechanical Properties of the Energy Levels of Diatomic Molecules: 8. The perturbation function; 9. Rotational distortion of spin multiplets; 10. Fine structure; 11. Perturbations and predissociation; 12. Even and odd levels; 13. Symmetrical and antisymmetrical levels; Part III. Selection Rules and Intensities in Diatomic Molecules: 14. General foundations; 15. Electronic bands; 16. Vibrational bands; 17. Rotational bands; 18. Band spectra and nuclear structure; 19. Transitions in the Stark and Zeeman effect; Part IV. Macroscopic Properties of Molecular Gases: 20. Scattering; 21. Dispersion; 22. Kerr and Faraday effect; 23. Dielectric constants; 24. Magnetic susceptibilities; 25. Specific heats; Part V. Molecule Formation and Chemical Binding: 26. Heteropolar molecules; 27. Homopolar molecules. Chemical forces between two H-atoms and two He-atoms; 28. The general theory of homopolar compounds; Bibliography; Subject index.

  6. 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.

  7. 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.

  8. Near infrared Raman spectra of Rhizoma dioscoreae

    NASA Astrophysics Data System (ADS)

    Lin, Wenshuo; Chen, Rong; Chen, Guannan; Feng, Sangyuan; Li, Yongzeng; Huang, Zufang; Li, Yongsen

    2008-03-01

    A novel and compact near-infrared (NIR) Raman system is developed using 785-nm diode laser, volume-phase technology holographic system, and NIR intensified charge-coupled device (CCD). Raman spectra and first derivative spectra of Rhizoma Dioscoreae are obtained. Raman spectra of Rhizoma Dioscoreae showed three strong characteristic peaks at 477.4cm -1, 863.9cm -1, and 936.0cm -1. The major ingredients are protein, amino acid, starch, polysaccharides and so on, matched with the known basic biochemical composition of Rhizoma Dioscoreae. In the first derivative spectra of Rhizoma Dioscoreae, distinguishing characteristic peaks appeared at 467.674cm -1, 484.603cm -1, 870.37cm -1, 943.368cm -1. Contrasted with Rhizoma Dioscoreae Raman spectra, in 600cm -1 to 800cm -1, 1000cm -1 to 1400cm -1 regions, changes in Rhizoma Dioscoreae Raman first derivative spectra are represented more clearly than Rhizoma Dioscoreae Raman spectra. So Rhizoma Dioscoreae raman first derivative spectra can be an accurate supplementary analysis method to Rhizoma Dioscoreae Raman spectra.

  9. 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.

  10. Trion spectra of semiconductor nanostructures

    NASA Astrophysics Data System (ADS)

    Esser, Axel; Runge, Erich; Zimmermann, Roland

    2001-03-01

    The linear optical properties of quantum wells and quantum wires in the presence of a moderate background carrier density nB are investigated theoretically and compared with recent experiments. At low n_B, excitons and trions (charged excitons) are the relevant excitations. We present a density-matrix approach, which starts from the interband polarization and couples directly to higher order correlation functions which are related to three-particle excitations. It allows to describe both trionic and excitonic states. A generalized dynamical truncation scheme is applied and yields an expression for the absorption coefficient of trions in terms of trion eigenstates. Then, in combination with a numerical solution of the three-particle Schrödinger equation we sucessfully model (i) experimental photoluminescence lineshapes (their asymmetry towards lower photon energy and temperature-dependence is related to carrier recoil) [1], (ii) radiative trion lifetime (shown to depend linearly on temperature for a thermalized trion distribution) [2], and (iii) the influence of an electrical field (quantum-confined Stark effect) [3]. The optical response of excitons and trions can be studied alternatively by the solution of the time-dependent trion Schrödinger equation yielding information about (i) the appearance of trion triplet states (shown to be optically inactice at vanishing center-of-mass momentum), and (ii) exciton-electron scattering states (which give rise to a broadening of the high-energy side of the exciton). Altogether, a consistent and thorough picture of exciton related absorption spectra in the presence of additional carriers can be derived either from density matrix theory or the solution of the time-dependent three-particle Schrödinger equation. [1] A. Esser et al., Phys. Rev. B 62, 8232 (2000); [2] V. Ciulin et al., Phys. Rev. B (2000); [3] A. Esser et al., Phys. Status Solidi B 221, 281 (2000).

  11. 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).

  12. Faster optical-spectra recording and analysis

    NASA Technical Reports Server (NTRS)

    Richmond, R. G.

    1977-01-01

    Optical spectra are recorded and rapidly analyzed by system that links multichannel analyzer and desk-top programable calculator. Cassette-memory storage is provided. System can be programed to automate background subtraction, axis expansion, and other data-analysis techniques and can store several hundred spectra for immediate or delayed analysis and comparisons.

  13. (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.

  14. Isotope shifts in spectra of molecular liquids

    NASA Astrophysics Data System (ADS)

    Dubrovskaya, E. V.; Kolomiitsova, T. D.; Shurukhina, A. V.; Shchepkin, D. N.

    2016-02-01

    In the IR absorption spectra of low-temperature molecular liquids, we have observed anomalously large isotope shifts of frequencies of vibrational bands that are strong in the dipole absorption. The same effect has also been observed in their Raman spectra. At the same time, in the spectra of cryosolutions, the isotope shifts of the same bands coincide with a high accuracy (±(0.1-0.5) cm-1) with the shifts that are observed in the spectra of the gas phase. The difference between the spectra of examined low-temperature systems is caused by the occurrence of resonant dipole-dipole interactions between spectrally active identical molecules. The calculation of the band contour in the spectrum of liquid freon that we have performed in this work taking into account the resonant interaction between states of simultaneous transitions in isotopically substituted molecules can explain this effect.

  15. PCA: Principal Component Analysis for spectra modeling

    NASA Astrophysics Data System (ADS)

    Hurley, Peter D.; Oliver, Seb; Farrah, Duncan; Wang, Lingyu; Efstathiou, Andreas

    2012-07-01

    The mid-infrared spectra of ultraluminous infrared galaxies (ULIRGs) contain a variety of spectral features that can be used as diagnostics to characterize the spectra. However, such diagnostics are biased by our prior prejudices on the origin of the features. Moreover, by using only part of the spectrum they do not utilize the full information content of the spectra. Blind statistical techniques such as principal component analysis (PCA) consider the whole spectrum, find correlated features and separate them out into distinct components. This code, written in IDL, classifies principal components of IRS spectra to define a new classification scheme using 5D Gaussian mixtures modelling. The five PCs and average spectra for the four classifications to classify objects are made available with the code.

  16. Blind extraction of exoplanetary spectra

    NASA Astrophysics Data System (ADS)

    Morello, Giuseppe; Waldmann, Ingo; Damiano, Mario; Tinetti, Giovanna

    2016-10-01

    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 chemical species in their atmospheres, and constraining their temperature and pressure profiles.Early analyses were somehow heuristic, 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 powerful 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, thence 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/WFC3, Hubble/NICMOS and Spitzer/IRS and Hubble/WFC3 in spectroscopy (Damiano, Morello et al., in prep., Waldmann 2012, 2014, Waldmann et al. 2013) with excellent

  17. 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

  18. Characteristics of energetic solar flare electron spectra

    NASA Technical Reports Server (NTRS)

    Moses, Dan; Droege, Wolfgang; Meyer, Peter; Evenson, Paul

    1989-01-01

    A 55 event survey of energy spectra of 0.1-100 MeV interplanetary electrons originating from solar flares as measured by two spectrometers onboard the ISEE 3 (ICE) spacecraft for the years 1978-1982 has been completed. Spectra generated using the maximum flux of a given event in each energy channel were restricted to events with a well-defined flux rise time. Two broad groups of electron spectra are considered. In one group, the spectra are well represented by a single power law in rigidity with spectral index in the range 3-4.5. The spectra in the other group deviate from a power law in rigidity systematically in that they harden with increasing rigidity. Events with near power-law spectra are found to be correlated with long-duration soft X-ray events, whereas those with hardening spectra are correlated with short-duration events. The possible variation of acceleration and propagation processes with the properties of the flare site is discussed, using the duration of the soft X-ray flare emission as an indicator of the physical parameters of the flare site (flare volume, density, coronal height, and magnetic field geometry).

  19. 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.

  20. 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.

  1. 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

  2. [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+.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  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. Vibrational and vibronic spectra of tryptamine conformers

    NASA Astrophysics Data System (ADS)

    Mayorkas, Nitzan; Bernat, Amir; Izbitski, Shay; Bar, Ilana

    2013-03-01

    Conformation-specific ionization-detected stimulated Raman spectra, including both Raman loss and Raman gain lines, along with visible-visible-ultraviolet hole-burning spectra of tryptamine (TRA) conformers have been measured simultaneously, with the aim of obtaining new data for identifying them. The slightly different orientations of the ethylamine side chain relative to the indole lead to unique spectral signatures, pointing to the presence of seven TRA conformers in the molecular beam. Comparison of ionization-loss stimulated Raman spectra to computationally scaled harmonic Raman spectra, especially in the alkyl C-H and amine N-H stretch regions together with the retrieved information on the stabilities of the TRA conformers assisted their characterization and structural identification. The prospects and limitations of using these spectroscopic methods as potential conformational probes of flexible molecules are discussed.

  9. 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.

  10. 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.

  11. Frequency Spectra of Magnetoacoustic Emission in Meteorites

    NASA Astrophysics Data System (ADS)

    Ivanchenko, S. V.; Grokhovsky, V. I.; Kolchanov, N. N.

    2016-08-01

    We analyzed the magnetoacoustic emission spectra of iron meteorites and their industrial analogs. The revealed differences in signal amplitude, position and width of the peaks are associated with the features of structure and the magnetic texture.

  12. 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

  13. Handbook of mass spectra of environmental contaminants

    SciTech Connect

    Hites, R.A.

    1985-01-01

    This handbook is a collection of the electron impact mass spectra of 394 commonly encountered environmental pollutants. Each page is devoted to the examination of a single pollutant, which is presented as a bar graph always starting at M/z = 40. Each spectra is determined by analyses of data in EPA data bases. The major fragment ions are correlated with their respective structure. The mass and intensity of the four most intense ions in the spectrum are given. Each spectrum is marked to indicate the origin of the selected fragment ions. For each spectra, also given are the approved name of the chemical Abstract Service, the common name of the compound, the article number (if any) given to the Merck Index, the CAS Registry Number, the molecular formula, and the nominal molecular weight of the compound. Each spectra is indexed by common chemical name, CAS Registry Number, exact molecular weight, and intense peaks.

  14. 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.

  15. Improved peak shape fitting in alpha spectra.

    PubMed

    Pommé, S; Caro Marroyo, B

    2015-02-01

    Peak overlap is a recurrent issue in alpha-particle spectrometry, not only in routine analyses but also in the high-resolution spectra from which reference values for alpha emission probabilities are derived. In this work, improved peak shape formulae are presented for the deconvolution of alpha-particle spectra. They have been implemented as fit functions in a spreadsheet application and optimum fit parameters were searched with built-in optimisation routines. Deconvolution results are shown for a few challenging spectra with high statistical precision. The algorithm outperforms the best available routines for high-resolution spectrometry, which may facilitate a more reliable determination of alpha emission probabilities in the future. It is also applicable to alpha spectra with inferior energy resolution. PMID:25497323

  16. PIA update: Correlation analyses of mass spectra

    NASA Technical Reports Server (NTRS)

    Mason, L. W.; Clark, B. C.

    1988-01-01

    The PIA instrument aboard the Giotto spacecraft (a time of flight spectrometer) has been presented elsewhere. The mass spectra used in this analysis were decoded and mass numbers assigned according to the presence of carbon and silver, using the global values for these elements in their spectral absence. The results presented here were obtained using a frequency of occurrence based on analysis which correlated how often mass numbers appear in the mass spectra and which mass numbers tend to occur together in the same spectra; no amplitude information is utilized. The data are presented as plots of mass vs coincident mass for different subsets of the PIA data set, with both axes having units of atomic mass. Frequency contours are plotted at approximately five percent contour intervals, relative to the maximum AMU occurrence in that plot. The plots presented are symmetrical about the matrix diagonal, i.e., every mass is coincident with itself in a given spectra.

  17. 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.

  18. 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.

  19. Establishment of the spectra of kinetic turbulence

    NASA Technical Reports Server (NTRS)

    Bolshov, L. A.; Dykhne, A. M.; Kiselev, V. P.; Pergament, A. K.

    1979-01-01

    An analysis of kinetic equations describing the establishment of Langmuir turbulence spectra is presented. Secondary turbulence occurs where stationary distribution consists of many peaks. The position of peaks is established and their amplitudes complete undamped oscillations. It is pointed out that establishing spectra can occur only during adiabatic inclusion of pumping. It is significant here that the adiabiatic condition is more rigid than the ordinary by several hundred times.

  20. 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.

  1. Tilted cranking classification of multiband spectra

    NASA Astrophysics Data System (ADS)

    Frauendorf, S.; May, F. R.

    1992-06-01

    The existence of TDHF-solutions rotating uniformly about a nonprincipal axis of the deformed axial potential is demonstrated. The solutions represent Delta(I) = 1 bands. Self consistency and symmetry are discussed. The transformation of experimental spectra to the rotating frame of reference is introduced. Excitation spectra at high spin are calculated and found to agree well with recent data on Er-163 and Hf-174.

  2. 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.

  3. [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

  4. 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.

  5. 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.

  6. [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.

  7. Climatology of tropospheric vertical velocity spectra

    NASA Technical Reports Server (NTRS)

    Ecklund, W. L.; Gage, K. S.; Balsley, B. B.; Carter, D. A.

    1986-01-01

    Vertical velocity power spectra obtained from Poker Flat, Alaska; Platteville, Colorado; Rhone Delta, France; and Ponape, East Caroline Islands using 50-MHz clear-air radars with vertical beams are given. The spectra were obtained by analyzing the quietest periods from the one-minute-resolution time series for each site. The lengths of available vertical records ranged from as long as 6 months at Poker Flat to about 1 month at Platteville. The quiet-time vertical velocity spectra are shown. Spectral period ranging from 2 minutes to 4 hours is shown on the abscissa and power spectral density is given on the ordinate. The Brunt-Vaisala (B-V) periods (determined from nearby sounding balloons) are indicated. All spectra (except the one from Platteville) exhibit a peak at periods slightly longer than the B-V period, are flat at longer periods, and fall rapidly at periods less than the B-V period. This behavior is expected for a spectrum of internal waves and is very similar to what is observed in the ocean (Eriksen, 1978). The spectral amplitudes vary by only a factor of 2 or 3 about the mean, and show that under quiet conditions vertical velocity spectra from the troposphere are very similar at widely different locations.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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

  13. Synthetic spectra: a tool for correlation spectroscopy.

    PubMed

    Sinclair, M B; Butler, M A; Ricco, A J; Senturia, S D

    1997-05-20

    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.

  14. 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.

  15. Janus Spectra in Two-Dimensional Flows.

    PubMed

    Liu, Chien-Chia; Cerbus, Rory T; Chakraborty, Pinaki

    2016-09-01

    In large-scale atmospheric flows, soap-film flows, and other two-dimensional flows, the exponent of the turbulent energy spectra, α, may theoretically take either of two distinct values, 3 or 5/3, but measurements downstream of obstacles have invariably revealed α=3. Here we report experiments on soap-film flows where downstream of obstacles there exists a sizable interval in which α transitions from 3 to 5/3 for the streamwise fluctuations but remains equal to 3 for the transverse fluctuations, as if two mutually independent turbulent fields of disparate dynamics were concurrently active within the flow. This species of turbulent energy spectra, which we term the Janus spectra, has never been observed or predicted theoretically. Our results may open up new vistas in the study of turbulence and geophysical flows. PMID:27661693

  16. 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.

  17. [Vibrational spectra of Hetian nephrite from Xinjiang].

    PubMed

    Zhang, Yong-wang; Liu, Yan; Liu, Tao-tao; Muhetaer, Zari; Liu, Yuan-qing

    2012-02-01

    In previous studies, EMPA, PIXE and others were employed to study the chemical compositions of nephrite separately without a systematical measurement. In the present study, XRF, XRD, IR and LR were used together to examine chemical and spectra characteristics of white, green and black nephrite from Hetian, Xinjiang. XRD results indicate that all nephrite samples consist of tremolite. Then IR spectra of nephrite samples suggest that the M-OH stretching vibration bands show that the M1 and M3 sites are not only occupied by Mg2+ and Fe2+, but also by Fe3+, which is consistent with the chemical compositions of these samples. This information might be useful to understanding the variety of nephrite. Their Raman spectra are almost the same, while some differences exist because of different content of FeO/Fe2O3.

  18. Multifrequency spectra of BL Lac objects

    NASA Technical Reports Server (NTRS)

    Urry, C. M.; Kondo, Y.; Mufson, S. L.; Wandel, A.

    1988-01-01

    A program to obtain simultaneous multifrequency spectra of BL Lacertae objects that are known X-ray sources is discussed. The IUE spectra are generally featureless and well-fitted by power law models. For the faintest exposures, Gaussian extraction of the spectrum can greatly impove the signal-to-noise. Most program objects vary in the ultraviolet, although the time scales are not known because of limited observing time. The broadband spectra of BL Lacs exhibit a range of characteristics but the curvature is always downward and the shape is generally smooth. This can be interpreted as synchrotron emission from a relativistic jet; different jet models are possible, and each allows a range of values for the bulk velocity, magnetic field strength, and electron density. Synchrotron models are not required, however an accretion disk model also gives a good fit to the ultraviolet-through-X-ray continuum.

  19. Janus Spectra in Two-Dimensional Flows

    NASA Astrophysics Data System (ADS)

    Liu, Chien-Chia; Cerbus, Rory T.; Chakraborty, Pinaki

    2016-09-01

    In large-scale atmospheric flows, soap-film flows, and other two-dimensional flows, the exponent of the turbulent energy spectra, α , may theoretically take either of two distinct values, 3 or 5 /3 , but measurements downstream of obstacles have invariably revealed α =3 . Here we report experiments on soap-film flows where downstream of obstacles there exists a sizable interval in which α transitions from 3 to 5 /3 for the streamwise fluctuations but remains equal to 3 for the transverse fluctuations, as if two mutually independent turbulent fields of disparate dynamics were concurrently active within the flow. This species of turbulent energy spectra, which we term the Janus spectra, has never been observed or predicted theoretically. Our results may open up new vistas in the study of turbulence and geophysical flows.

  20. Thermal Infrared Spectra of Experimentally Shocked Albitite

    NASA Astrophysics Data System (ADS)

    Johnson, J. R.; Horz, F.; Lucey, P.; Christensen, P.

    2002-12-01

    We have acquired thermal infrared (3-40 microns) hemispherical reflectance and emissivity spectra of shocked samples of a fine-grained (1-5 mm) albitite from Szklary, Poland to determine the spectral degradation effects of shocked albite as a function of increasing shock pressures (17-56 GPa). Reflectance data were acquired using a Nicolet 5SXC FTIR spectrometer at the HIGP, University of Hawaii, and emission spectra were acquired using a Nicolet Nexus 670 emission spectrometer at Arizona State University. These data complement similar previous measurements of experimentally shocked anorthosite relevant to interpreting spectra provided by the Thermal Emission Spectrometer (TES) on Mars Global Surveyor. The samples were shocked using the 25-mm barrel gun at Johnson Space Center and provided ~400 mg per sample. Large (2-10 mm) chips of recovered material were separated from the samples and washed to remove clinging fines, and the residual was powdered to provide a consistent grain size (~20 microns). Spectra were obtained of both the chips and the powder samples. Results for the chips show a progressive loss of spectral features and contrast compared to unshocked samples, while results for the powders show a reduction in the depth of the transparency feature located near 855 wavenumbers (11.7 microns) with increasing pressure. The albite structure retains its crystalline state to higher pressures than anorthosites, consistent with previous transmission spectra. Additional visible/near-infrared (0.35-2.50 microns) measurements of the powdered albitite and anorthosite samples also were acquired at the RELAB facility. These spectra show a decrease in albedo and a loss of water bands near 1.4 and 1.9 microns with increasing pressure. The broad feldspar absorption near 1.25 microns was not present in the albitite sample (possibly due to its fine original grain size) but was present in the anorthosite sample, where its band depth decreased with increasing shock pressures.

  1. Unmixing Space Object's Moderate Resolution Spectra

    NASA Astrophysics Data System (ADS)

    Dao, P.; Dentamaro, A.; Ryan, B.; Ryan, E.

    2013-09-01

    Many non-resolved techniques have been proposed and explored to infer space object's characteristics that may lend insight to object's identification and status. The latter attributes are hard to obtain in the absence of resolved imagery, as for objects not in Low Earth Orbit or for small-sized ones. Spectral unmixing is a non-resolved technique that derives an object's material composition from one or a series of spectra. While spectral unmixing techniques have been tested with space objects and spectrometric visible spectra, with spectral width smaller than 0.4 nanometers and over 100 spectral channels, its success against moderately resolved spectra has not been verified. An example of a moderate resolution sensor is that of a slit-less spectrograph which is desirable because of its simple implementation and arguably better temporal fidelity than systems with a slit. A moderate number of spectral bands are considered a challenge when the number of bands is much smaller than the number of material candidate spectra. We develop the Spectral Unmixing for Space Objects (SUSO) algorithm based on Sparse Recovery optimization techniques to deal with this challenge. Sparse recovery, a specialty area of Compressive Sensing, capitalizes on the knowledge that, while the number of candidate materials is expansive, the external surface of a satellite is effectively composed of a few representative materials. We discuss the technique and show the results of applying it on a number of simulated and measured spectra. Simulated signatures are in the Visible and reflective IR, and measured signatures were made with the Magdalena Ridge Observatory's slit-less spectrograph which is based on a CCD and grating combination mounted on a 2.4 m telescope. We studied the preservation of temporal information when a time series of spectra is analyzed by SUSO and the prospect of augmenting typical shape recovery with material attribution.

  2. Rotational Spectra of Phenylalanine, Tirosine and Tryptophan

    NASA Astrophysics Data System (ADS)

    Mata, S.; Perez, C.; Sanz, M. E.; Blanco, S.; López, J. C.; Alonso, J. L.

    2009-06-01

    The rotational spectra of the aromatic natural amino acids phenylalanine, tyrosine and tryptophan have been investigated by Laser Ablation Molecular Beam Fourier transform Microwave Spectroscopy LA-MB-FTMW. The spectra of two rotamers of phenylalanine have been detected in the supersonic expansion. Both forms are stabilized by a chain of intramolecular hydrogen bonds O-H\\cdotsN-H\\cdots{π}, being the carboxylic group incis configuration. One conformer of tyrosine, which only differs from phenylalanine in a -OH group inpara position, has been also characterized. Preliminary results on the rotational spectrum of tryptophan are presented.

  3. Gravitational effects on planetary neutron flux spectra

    NASA Astrophysics Data System (ADS)

    Feldman, W. C.; Drake, D. M.; O'dell, R. D.; Brinkley, F. W.; Anderson, R. C.

    1989-01-01

    The effects of gravity on the planetary neutron flux spectra for planet Mars, and the lifetime of the neutron, were investigated using a modified one-dimensional diffusion accelerated neutral-particle transport code, coupled with a multigroup cross-section library tailored specifically for Mars. The results showed the presence of a qualitatively new feature in planetary neutron leakage spectra in the form of a component of returning neutrons with kinetic energies less than the gravitational binding energy (0.132 eV for Mars). The net effect is an enhancement in flux at the lowest energies that is largest at and above the outermost layer of planetary matter.

  4. Parallel Genetic Algorithm for Alpha Spectra Fitting

    NASA Astrophysics Data System (ADS)

    García-Orellana, Carlos J.; Rubio-Montero, Pilar; González-Velasco, Horacio

    2005-01-01

    We present a performance study of alpha-particle spectra fitting using parallel Genetic Algorithm (GA). The method uses a two-step approach. In the first step we run parallel GA to find an initial solution for the second step, in which we use Levenberg-Marquardt (LM) method for a precise final fit. GA is a high resources-demanding method, so we use a Beowulf cluster for parallel simulation. The relationship between simulation time (and parallel efficiency) and processors number is studied using several alpha spectra, with the aim of obtaining a method to estimate the optimal processors number that must be used in a simulation.

  5. 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.

  6. Separating Peaks in X-Ray Spectra

    NASA Technical Reports Server (NTRS)

    Nicolas, David; Taylor, Clayborne; Wade, Thomas

    1987-01-01

    Deconvolution algorithm assists in analysis of x-ray spectra from scanning electron microscopes, electron microprobe analyzers, x-ray fluorescence spectrometers, and like. New algorithm automatically deconvolves x-ray spectrum, identifies locations of spectral peaks, and selects chemical elements most likely producing peaks. Technique based on similarities between zero- and second-order terms of Taylor-series expansions of Gaussian distribution and of damped sinusoid. Principal advantage of algorithm: no requirement to adjust weighting factors or other parameters when analyzing general x-ray spectra.

  7. FIT3D: Fitting optical spectra

    NASA Astrophysics Data System (ADS)

    Sánchez, S. F.; Pérez, E.; Sánchez-Blázquez, P.; González, J. J.; Rosales-Ortega, F. F.; Cano-Díaz, M.; López-Cobá, C.; Marino, R. A.; Gil de Paz, A.; Mollá, M.; López-Sánchez, A. R.; Ascasibar, Y.; Barrera-Ballesteros, J.

    2016-09-01

    FIT3D fits optical spectra to deblend the underlying stellar population and the ionized gas, and extract physical information from each component. FIT3D is focused on the analysis of Integral Field Spectroscopy data, but is not restricted to it, and is the basis of Pipe3D, a pipeline used in the analysis of datasets like CALIFA, MaNGA, and SAMI. It can run iteratively or in an automatic way to derive the parameters of a large set of spectra.

  8. 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.

  9. NMR spectra of androstane analogs of brassinosteroids

    NASA Astrophysics Data System (ADS)

    Baranovskii, A. V.; Litvinovskaya, R. P.; Aver'kova, M. A.; Khripach, N. B.; Khripach, V. A.

    2007-09-01

    We have used two-dimensional NMR spectroscopy to make a complete assignment of signals from the nuclei of hydrogen and carbon atoms in the spectra of brassinosteroids in the androstane series. We have confirmed the stereochemistry of the chiral centers and the structure of the molecules. We have studied the effect of the configuration of the 2,3-diol groups in the A ring of the steroids on the chemical shift of adjacent atoms in the 13C and 1H NMR spectra.

  10. 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

  11. Calculated late time spectra of supernovae

    SciTech Connect

    Axelrod, T.S.

    1987-10-30

    We consider here the nebular phase spectra of supernovae whose late time luminosity is provided by the radioactive decay of /sup 56/Ni and /sup 56/Co synthesized in the explosion. A broad variety of supernovae are known or suspected to fall in this category. This includes all SNIa and SNIb, and at least some SNII, in particular SN1987a. At sufficiently late times the expanding supernova becomes basically nebular in character due to its decreasing optical depth. The spectra produced during this stage contain information on the density and abundance structure of the entire supernova, as opposed to spectra near maximum light which are affected only by the outermost layers. A numerical model for nebular spectrum formation is therefore potentially very valuable for answering currently outstanding questions about the post-explosion supernova structure. As an example, we can hope to determine the degree of mixing which occurs between the layers of the ''onion-skin'' abundance structure predicted by current one dimensional explosion calculations. In the sections which follow, such a numerical model is briefly described and then applied to SN1972e, a typical SNIa, SN1985f, an SNIb, and finally to SN1987a. In the case of SN1987a predicted spectra are presented for the wavelength range from 1 to 100 microns at a time 300 days after explosion. 18 refs., 6 figs.

  12. Stability properties of wines by absorption spectra

    NASA Astrophysics Data System (ADS)

    Larena, A.; Vega, J.

    1986-03-01

    The temporal evolution of absorption spectra (370-700 nm) of different spanish wines has been studied by us under the influence of air presence, and the light exposition. In particular, we have exposed the wines to a magenta light. Nevertheless, the color coordinates of wine show a little relative variation (0.1-1 %)

  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. Prompt fission neutron spectra of actinides

    DOE PAGES

    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.

  16. 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.

  17. 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.

  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. 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.

  20. Synthetic spectra for the Arizona Airglow Experiment

    SciTech Connect

    Johnston, J.E.; Hatfield, D.B.; Broadfoot, A.L.

    1994-12-31

    The Arizona Airglow Experiment (GLO) is a panchromatic Intensified CCD (ICCD) spectrograph, bore sighted with 12 monochromatic imagers. The spectrograph provides continuous spectral coverage from 1150 {angstrom} to 11,000 {angstrom} with a resolution of 5 {angstrom} to 20 {angstrom}. The spectrograph was designed to record simultaneously as much information as possible from a single column of gas. The resolution was selected to allow the determination of molecular emission vibrational and rotational structure. Molecular band emissions contain much more information than atomic lines, although interpretation of band emissions is more complicated. This complexity is due to the distribution of their energies over broad spectral ranges that overlap. The most productive method of interpreting molecular spectra is by modeling. The nature of the molecular transitions is well known, and synthetic spectra can be calculated to match the recorded spectrum accurately. Their knowledge of the transition probabilities allows accurate estimates of the intensity and shape of blended bands. It is the goal to synthesize all of the emissions recorded by the GLO as a tool to aid in detailed analysis of spectra. This work describes the approach used in calculating the synthetic spectra and references the source of parameters used for 14 band systems. This software utility will become a part of the GLO facility.

  1. 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...

  2. Processing and classification of protein mass spectra.

    PubMed

    Hilario, Melanie; Kalousis, Alexandros; Pellegrini, Christian; Müller, Markus

    2006-01-01

    Among the many applications of mass spectrometry, biomarker pattern discovery from protein mass spectra has aroused considerable interest in the past few years. While research efforts have raised hopes of early and less invasive diagnosis, they have also brought to light the many issues to be tackled before mass-spectra-based proteomic patterns become routine clinical tools. Known issues cover the entire pipeline leading from sample collection through mass spectrometry analytics to biomarker pattern extraction, validation, and interpretation. This study focuses on the data-analytical phase, which takes as input mass spectra of biological specimens and discovers patterns of peak masses and intensities that discriminate between different pathological states. We survey current work and investigate computational issues concerning the different stages of the knowledge discovery process: exploratory analysis, quality control, and diverse transforms of mass spectra, followed by further dimensionality reduction, classification, and model evaluation. We conclude after a brief discussion of the critical biomedical task of analyzing discovered discriminatory patterns to identify their component proteins as well as interpret and validate their biological implications.

  3. Students' Mental Models of Atomic Spectra

    ERIC Educational Resources Information Center

    Körhasan, Nilüfer Didis; Wang, Lu

    2016-01-01

    Mental modeling, which is a theory about knowledge organization, has been recently studied by science educators to examine students' understanding of scientific concepts. This qualitative study investigates undergraduate students' mental models of atomic spectra. Nine second-year physics students, who have already taken the basic chemistry and…

  4. 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

  5. Spectra of the supernova SN1999by

    NASA Astrophysics Data System (ADS)

    Gavin, M.

    1999-08-01

    Spectra of SN1999by by Maurice Gavin. 30cm SCT+Rainbow grating+MX9 CCD; dispersion 4nm/pixel. 1999 May 2, 6, 10; 15m-35m exp. Spectrogram [at top] electronically stretched; profiles via Pixwin software.

  6. 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

  7. An Interactive Gallery of Planetary Nebula Spectra

    NASA Astrophysics Data System (ADS)

    Kwitter, K. B.; Henry, R. B. C.

    2002-12-01

    We have created a website containing high-quality moderate-resolution spectra of 88 planetary nebulae (PNe) from 3600 to 9600 Å, obtained at KPNO and CTIO. Spectra are displayed in a zoomable window, and there are templates available that show wavelength and ion identifications. In addition to the spectra themselves, the website also contains a brief discussion of PNe as astronomical objects and as contributors to our understanding of stellar evolution, and a table with atlas information for each object along with a link to an image. This table can be re-ordered by object name, galactic or equatorial coordinates, distance from the sun, the galactic center, or the galactic plane. We envision that this website, which concentrates a large amount of data in one place, will be of interest to a variety of users. PN researchers might need to check the spectrum of a particular object of interest; the non-specialist astronomer might simply be interested in perusing such a collection of spectra; and finally, teachers of introductory astronomy can use this database to illustrate basic principles of atomic physics and radiation. To encourage such use, we have written two simple exercises at a basic level to introduce beginning astronomy students to the wealth of information that PN spectra contain. We are grateful to Adam Wang of the Williams College OIT and to his summer student teams who worked on various apects of the implementation of this website. This work has been supported by NSF grant AST-9819123 and by Williams College and the University of Oklahoma.

  8. Savannah River Site disaggregated seismic spectra

    SciTech Connect

    Stephenson, D.E.

    1993-02-01

    The objective of this technical note is to characterize seismic ground motion at the Savannah River Site (SRS) by postulated earthquakes that may impact facilities at the site. This task is accomplished by reviewing the deterministic and probabilistic assessments of the seismic hazard to establish the earthquakes that control the hazard to establish the earthquakes that control the hazard at the site and then evaluate the associated seismic ground motions in terms of response spectra. For engineering design criteria of earthquake-resistant structures, response spectra serve the function of characterizing ground motions as a function of period or frequency. These motions then provide the input parameters that are used in the analysis of structural response. Because they use the maximum response, the response spectra are an inherently conservative design tool. Response spectra are described in terms of amplitude, duration, and frequency content, and these are related to source parameters, travel path, and site conditions. Studies by a number of investigators have shown by statistical analysis that for different magnitudes the response spectrum values are different for differing periods. These facts support Jennings' position that using different shapes of design spectra for earthquakes of different magnitudes and travel paths is a better practice than employing a single, general-purpose shape. All seismic ground motion characterization results indicate that the PGA is controlled by a local event with M[sub w] < 6 and R < 30km. The results also show that lower frequencies are controlled by a larger, more distant event, typically the Charleston source. The PGA of 0.2 g, based originally on the Blume study, is consistent with LLNL report UCRL-15910 (1990) and with the DOE position on LLNL/EPRI.

  9. Savannah River Site disaggregated seismic spectra

    SciTech Connect

    Stephenson, D.E.

    1993-02-01

    The objective of this technical note is to characterize seismic ground motion at the Savannah River Site (SRS) by postulated earthquakes that may impact facilities at the site. This task is accomplished by reviewing the deterministic and probabilistic assessments of the seismic hazard to establish the earthquakes that control the hazard to establish the earthquakes that control the hazard at the site and then evaluate the associated seismic ground motions in terms of response spectra. For engineering design criteria of earthquake-resistant structures, response spectra serve the function of characterizing ground motions as a function of period or frequency. These motions then provide the input parameters that are used in the analysis of structural response. Because they use the maximum response, the response spectra are an inherently conservative design tool. Response spectra are described in terms of amplitude, duration, and frequency content, and these are related to source parameters, travel path, and site conditions. Studies by a number of investigators have shown by statistical analysis that for different magnitudes the response spectrum values are different for differing periods. These facts support Jennings` position that using different shapes of design spectra for earthquakes of different magnitudes and travel paths is a better practice than employing a single, general-purpose shape. All seismic ground motion characterization results indicate that the PGA is controlled by a local event with M{sub w} < 6 and R < 30km. The results also show that lower frequencies are controlled by a larger, more distant event, typically the Charleston source. The PGA of 0.2 g, based originally on the Blume study, is consistent with LLNL report UCRL-15910 (1990) and with the DOE position on LLNL/EPRI.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. Reflectance spectra of mafic silicate-opaque assemblages with applications to meteorite spectra

    NASA Technical Reports Server (NTRS)

    Cloutis, Edward A.; Smith, Dorian G. W.; Lambert, Richard St. J.; Gaffey, Michael J.

    1990-01-01

    The addition of fine-grained magnetite to mafic silicate spectra can impart not only an overall blue slope, but also lower overall reflectance and band intensities. The reflectance spectra of the CO and CV magnetite-bearing carbonaceous chondrites are noted to exhibit many of these features; the low band depths of these meteorites suggest that an additional dark, neutral phase, such as ordered carbon, is present. Carbon + mafic silicate spectra possess a red overall slope at low amorphous carbon concentrations. The parent bodies of some of the darkest meteorites should exhibit spectral features attributable to mafic silicates.

  16. Thermal Infrared Spectra of Experimentally Shocked Basalt

    NASA Astrophysics Data System (ADS)

    Johnson, J. R.; Horz, F.

    2003-12-01

    We acquired thermal infrared (3-40 microns) emissivity and hemispherical reflectance spectra of experimentally shocked samples of a fine-grained basalt from Grand Falls, AZ to document the spectral effects of shock as a function of increasing shock pressures (17-57 GPa). This sample contains 25% pyroxene, 20% olivine, and 45% feldspar, making it a suitable analog to the Surface Type 1 (basalt) observed in Thermal Emission Spectrometer (TES) data of Mars. Reflectance data (3-14 microns) were acquired using a Nexus 470 FTIR spectrometer at the HIGP, University of Hawaii, and emission spectra (5-40 microns) were acquired using a Nicolet Nexus 670 emission spectrometer at Arizona State University. These data complement similar previous measurements of experimentally shocked plagioclase and pyroxene relevant to interpreting spectra provided by TES. The samples were shocked using the 25-mm barrel gun at Johnson Space Center and provided ~400 mg per sample. Large (2-10 mm) chips of recovered material were separated from the samples and washed to remove clinging fines, and the residual was powdered to provide a consistent grain size ( ˜20 microns). Spectra were obtained of both the chips and the powder samples. Results for the chips show a shift in band positions in the 900-1200 wavenumber (wn) region compared to unshocked samples, consistent with the structural degradation of feldspar and subsequent formation of maskelynite and glass. The development of a band near 460 wn at high pressures is also consistent with glass formation in feldspars. Conversely, absorptions related to pyroxene remain present even at high pressures, consistent with previous work. Results for the powders show little variations with increasing pressure except for the loss of minor transparency features in the 800-900 wn region. Additional visible/near-infrared (0.35-2.50 microns) measurements of the powdered basalt samples also will be acquired at the RELAB facility. Future work will include

  17. 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.

  18. 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.

  19. 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.

  20. Raman spectra of shocked minerals. I. Olivine

    SciTech Connect

    Heymann, D.; Celucci, T.A.

    1988-12-01

    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. 54 references.

  1. 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.

  2. Control of photodetachment spectra through laser dressing

    NASA Astrophysics Data System (ADS)

    Morrison, Nathan; Greene, Chris

    2013-05-01

    Photodetachment and photoionization spectra often display rich resonance structures. The properties of these spectra can be modified through dressing with intense laser fields, providing control over photon absorption and the emitted electron. We present a Floquet R-matrix method for calculating photodetachment cross sections in the presence of a dressing laser. The full wave functions in the Floquet formalism for bound and escaping electrons are found by solving the Schrödinger equation near the atomic core and applying analytic boundary conditions outside of the interaction region. These calculations are used to investigate the modification of existing resonances, such as modifying the shape, or q parameter, of Feshbach resonances. We also investigate the creation of new resonances in cases where high-lying bound states become autoionizing through the absorption of dressing laser photons. This work was supported by the DOE.

  3. Infrared spectra of FHF - in alkali halides

    NASA Astrophysics Data System (ADS)

    Chunnilall, C. J.; Sherman, W. F.

    1982-03-01

    The bifluoride ion, FHF -, has been substitutionally isolated within single crystal samples of several different alkali halides. Infrared spectra of these crystals have been studied for sample temperatures down to 8K when half-bandwidths of less than 1 cm -1 have been observed. (Note that at room temperature ν 3 is observed to have a half-bandwidth of about 40 cm -1). The frequency shifts and half-bandwidth changes caused by cooling are considered together with the frequency shifts caused by pressures up to 10 k bar. The low temperature spectra clearly indicate that FHF - is a linear symmetrical ion when substitutionally isolated within alkali halides of either the NaCl or CsCl structure.

  4. Raman spectra of seven interplanetary dust particles

    NASA Technical Reports Server (NTRS)

    Xu, Yin-Lin; Yu, Min; Fan, Chang-Yun

    1992-01-01

    The Raman shift spectra of seven interplanetary dust particles, U2034(F10), U2034(F8), U2022(B1), W7074 18, W7074 C15, W7074 C3 and W7074 A7, were measured with a Spex-1403 Raman spectrograph. The exciting radiations were the 488 nm and 514 nm line of a 5W argon ion laser. All seven spectra exhibit the 1350 and 1600 Delta/cm arbon bands, implying that the Interplanetary dust particles were coated with hydrocarbon and incompletely crystallized carbon, the part of which may be the residue of hydrocarbon contents in the particles after water loss by the heating during their entry into the earth's atmosphere. A weak band structure in the 520-610/cm range could be caused by cyclosilicates, and a weak band at 2900/cm is tentatively identified as due to hydrocarbon molecules.

  5. 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.

  6. Anharmonic Vibrational Spectra of Hydrogen Bonded Clusters

    NASA Astrophysics Data System (ADS)

    Xantheas, Sotiris S.

    2006-03-01

    We report anharmonic vibrational spectra for a variety of hydrogen bonded clusters such as (H2O)n and (HF)n, n=1-5. We investigate the convergence of the hydrogen bonded frequencies with basis set and level of electron correlation and compare with the available experimental data. For this purpose we employ the correlation-consistent basis sets up to quintuple zeta (5z) quality and compute the spectra at the second order Møller-Plesset (MP2) and Coupled Cluster plus Single and Double with perturbative estimate of Triple excitations [CCSD(T)]. The correlation between the calculated elongations in the hydrogen bonding stretches and the corresponding computed/observed vibrational frequencies suggest an extension of Badger's rule for these hydrogen bonded systems.

  7. Cathodoluminescence spectra of gallium nitride nanorods

    PubMed Central

    2011-01-01

    Gallium nitride [GaN] nanorods grown on a Si(111) substrate at 720°C via plasma-assisted molecular beam epitaxy were studied by field-emission electron microscopy and cathodoluminescence [CL]. The surface topography and optical properties of the GaN nanorod cluster and single GaN nanorod were measured and discussed. The defect-related CL spectra of GaN nanorods and their dependence on temperature were investigated. The CL spectra along the length of the individual GaN nanorod were also studied. The results reveal that the 3.2-eV peak comes from the structural defect at the interface between the GaN nanorod and Si substrate. The surface state emission of the single GaN nanorod is stronger as the diameter of the GaN nanorod becomes smaller due to an increased surface-to-volume ratio. PMID:22168896

  8. 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

  9. 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

  10. Simulation of mammographic x-ray spectra.

    PubMed

    Johnson, G A; O'Foghludha, F

    1980-01-01

    Attempts to simulate Mo-anode spectra for film mammography by using Mo filters with W-anode tubes have been reported by several workers, and others have generated W-like continua for xeromammographic purposes by heavy Al filtration of Mo-anode tubes. In the present work the success of these simulations was tested by Si(Li) spectrometric methods that measured the spectral shapes and the exposure levels. Comparisons of Mo-anode/Al-filter with W-anode/Al-filter combinations were made, and also of W-anode/M-filter with Mo-anode/Mo-folter combinations. In certain circumstance the spectral shape is moderately well simulated but in all cases the useful output is less in the simulations than in the original spectra. The general conclusion is that simulation is always less attractive than direct use of the desired anode. PMID:7393143

  11. Simulation of mammographic x-ray spectra

    SciTech Connect

    Johnson, G.A.; O'Foghludha, F.

    1980-05-01

    Attempts to simulate Mo-anode spectra for film mammography by using Mo filters with W-anode tubes have been reported by several workers, and others have generated W-like continua for xeromammographic purposes by heavy A1 filtration of Mo-anode tubes. In the present work the success of these simulations was tested by Si(Li) spectrometric methods that measured the spectral shapes and the exposure levels. Comparisons of Mo-anode/A1-filter with W-anode/A1-filter combinations were made, and also of W-anode/M-filter with Mo-anode/Mo-folter combinations. In certain circumstance the spectral shape is moderately well simulated but in all cases the useful output is less in the simulations than in the original spectra. The general conclusion is that simulation is always less attractive than direct use of the desired anode.

  12. 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.

  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. 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.

  15. 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.

  16. High resolution derivative spectra in remote sensing

    NASA Technical Reports Server (NTRS)

    Demetriades-Shah, Tanvir H.; Steven, Michael D.; Clark, Jeremy A.

    1990-01-01

    The use of derivative spectra is an established technique in analytical chemistry for the elimination of background signals and for resolving overlapping spectral features. Application of this technique for tackling analogous problems such as interference from soil background reflectance in the remote sensing of vegetation or for resolving complex spectra of several target species within individual pixels in remote sensing is proposed. Methods for generating derivatives of high spectral resolution data are reviewed. Results of experiments to test the use of derivatives for monitoring chlorosis in vegetation show that derivative spectral indices are superior to conventional broad-band spectral indices such as the near-infrared/red reflectance ratio. Conventional broad-band indices are sensitive to both leaf cover as well as leaf color. New derivative spectral indices which were able to monitor chlorosis unambiguously were identified. Potential areas for the application of this technique in remote sensing are considered.

  17. Model atmospheres, predicted spectra, and colors

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Theoretical models of stellar atmospheres and the process of forming a spectrum are reviewed with particular reference to the spectra of B stars. In the case of classical models the stellar atmosphere is though to consist of plane parallel layers of gas in which radiative and hydrostatic equilibrium exists. No radiative energy is lost or gained in the model atmosphere, but the detailed shape of the spectrum is changed as a result of the interactions with the ionized gas. Predicted line spectra using statistical equilibrium local thermodynamic equilibrium (LTE), and non-LTE physics are compared and the determination of abundances is discussed. The limitations of classical modeling are examined. Models developed to demonstrate what motions in the upper atmosphere will do to the spectrum and to explore the effects of using geometries different from plane parallel layer are reviewed. In particular the problem of radiative transfer is addressed.

  18. 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.

  19. 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.

  20. 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.

  1. Density fluctuation spectra in magnetohydrodynamic turbulence

    NASA Technical Reports Server (NTRS)

    Montgomery, D.; Brown, M. R.; Matthaeus, W. H.

    1987-01-01

    It is shown that within the framework of nearly incompressible magnetohydrodynamics, but not within that of neutral-fluid hydrodynamics, a k exp -5/3 inertial-range wave number density fluctuation spectrum is to be expected at the same times that k exp -5/3 kinetic energy and magnetic energy cascade spectra are present. A previous discrepancy between theory and observation in the local interstellar medium and solar wind is thereby resolved.

  2. 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.

  3. Electronic spectra of astrophysically interesting cations

    SciTech Connect

    Maier, John P. Rice, Corey A. Mazzotti, Fabio J. Johnson, Anatoly

    2015-01-22

    The electronic spectra of polyacetylene cations were recorded at 20K in the laboratory in an ion trap instrument. These can then be compared with diffuse interstellar band (DIB) absorptions. Examination of recently published data shows that the attribution of a weak DIB at ∼506.9 nm to diacetylene cation is not justified. Study of the higher excited electronic states of polyacetylene cations shows that their widths can still be sufficiently narrow for consideration as DIB carriers.

  4. 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.

  5. Spikes in Brewer spectroradiometer UV spectra

    NASA Astrophysics Data System (ADS)

    Meinander, O.; Josefsson, W.; Kaurola, J.; Koskela, T.; Lakkala, K.

    2003-04-01

    The occurrence of spikes in Brewer UV spectra has been studied. By a spike we mean an anomalous number of counts recorded in one wavelength channel causing an abrupt upwards or downwards change in value that does not originate from the true radiation signal. We have recorded downward spikes in lamp scans measured in the darkroom, and spikes occur in sky measurements as well. We analyzed continuous measurement data over several years, with more than 90 000 spectra, from one single monochromator and two double monochromator Brewers. We found that especially the double monochromators may suffer from more than 200 spikes per ~5000 annual spectra. The spikes were not always randomly distributed over the wavelength range. The single monochromator was found to have a significant number of spikes at wavelengths below 300 nm, indicating possible bias in the stray light correction unless taken into consideration. The error caused by non-corrected spikes varied greatly from case to case. For example, the effect of one moderate-size spiked was found to be more than 5 % on a DNA action dose rate and close to 1 % on a DNA action daily dose. When high accuracy of the in situ UV measurements is required, our results suggest a need to remove spikes from the spectra. We used a simple statistical approach. Other slightly different approaches exist as well. Our data showed that ancillary radiation measurements may be necessary to interpret the data correctly. Under rapidly-changing cloudiness it can be difficult to distinguish between noise spikes and the variation in irradiance due to changes in the state of the sky.

  6. CUBISM: CUbe Builder for IRS Spectra Maps

    NASA Astrophysics Data System (ADS)

    Sings Irs Team; Smith, J. D.; Armus, Lee; Bot, Caroline; Buckalew, Brent; Dale, Danny; Helou, George; Jarrett, Tom; Roussel, Helene; Sheth, Kartik

    2011-11-01

    CUBISM, written in IDL, is a tool for constructing spectral cubes, maps, and arbitrary aperture 1D spectral extractions from sets of mapping mode spectra taken with Spitzer's IRS spectrograph. CUBISM is optimized for non-sparse maps of extended objects, e.g. the nearby galaxy sample of SINGS, but can be used with data from any spectral mapping AOR (primarily validated for maps which are designed as suggested by the mapping HOWTO).

  7. Nonlinear matter spectra in growing neutrino quintessence

    SciTech Connect

    Brouzakis, N.; Tetradis, N.; Pettorino, V.; Wetterich, C. E-mail: pettorin@sissa.it E-mail: c.wetterich@thphys.uni-heidelberg.de

    2011-03-01

    We investigate the nonlinear power spectra of density perturbations and acoustic oscillations in growing neutrino quintessence. In this scenario, the neutrino mass has a strong dependence on the quintessence field. The induced coupling stops the evolution of the field when the neutrinos become nonrelativistic, and triggers the transition to the accelerating phase of the cosmological expansion. For the calculation of the nonlinear spectra we employ the time renormalization group, which resums subsets of diagrams of arbitrarily high order in cosmological perturbation theory. At redshifts around five, the neutrino fluctuations are still linear and acoustic oscillations are present in the neutrino power spectrum, induced by the acoustic oscillations in the baryonic and dark-matter sectors. The neutrino perturbations become nonlinear at redshifts around three. The mode coupling generated by the nonlinearities erases the oscillations in the neutrino spectrum at some redshift above two. There is a potential danger that at later times the influence of the gravitational potentials induced by the neutrino inhomogeneities could erase the oscillations from the baryonic and dark-matter spectra, making the scenario incompatible with observations. For the scenario to be viable, the neutrino-induced gravitational potentials in the range of baryon acoustic oscillations should not grow to average values much larger than 10{sup −4}. The magnitude of the expected potentials is still not known reliably, as the process of structure formation is poorly understood in growing neutrino quintessence. The time renormalization group cannot describe the effects of nonlinear clustering. Alternative methods, such as hydrodynamic simulations, must be empoloyed for the calculation of the spectra at low redshifts.

  8. 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.

  9. 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.

  10. Optical spectra in Fibonacci photonic nanostructures

    NASA Astrophysics Data System (ADS)

    Albuquerque, E. L.; de Medeiros, F. F.; da Silva, L. R.

    2007-03-01

    In this work, we have studied the transmission spectra of photonic band-gap Fibonacci quasiperiodic nanostructures composed of both positive (SiO2) and negative refractive index (n) materials, the so-called metamaterials. These left-handed materials has been receiving recently a lot of attention due to their novel properties, like the possibility of the construction of perfect lenses. Also, the mirror symmetry structure is very sensitive to the phase compensation effect, which is unique in the positive and negative refractive index stacked Fibonacci nanostructures. The transmission spectra of these Fibonacci nanostructures, for the case where both refractive index can be approximated as a constant, show a strike self-similarity behavior, and perfect transmission peaks are observed due to its internal coupling between localized modes and propagation modes, enabling the structure to be used as an ideal optical filter. For more realistic case, where the permittivity is modelled by a plasmonic dielectric function, there is no more a self-similar pattern, although keeping Bragg refraction gaps. In both cases, however, our transmission spectra unveil smooth structure due to the phase compensation effect, including the so-called zero-n gap case.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Mixing model analysis of telescopic lunar spectra

    NASA Astrophysics Data System (ADS)

    Lucey, Paul G.; Clark, Beth C.; Hawke, B. Ray

    1993-03-01

    We have analyzed very high quality reflectance spectra of the lunar surface from the University of Hawaii lunar spectral data collection using a spectral mixing model. The spectra analyzed are those of 45 mare sites and 75 highland sites. The spectra were selected on the basis of very high signal to noise ratios based on error bars and point to point scatter, and on quality of removal of telluric water bands. The spectral mixing model used 7 components, not all of which were used in each fit. Four of the components were mineral spectra of the orthopyroxene, a clinopyroxene, an olivine and an anorthite, measured at the Brown University's RELAB. All of the minerals were 45-90 micron splits. Lunar soil contains other components which have the effect of reddening and darkening the soil as well as reducing spectral contrast. In addition, lunar soil contains spectral neutral bright material (likely very fine grained feldspar) which serves to reduce spectral contrast and brighten soils. Early attempts to fit many of the spectra pointed out the need for a component which has a very broad smooth absorption feature centered near 1.1 microns. Glass is a good candidate for this component. For the bright component we used a flat reflectance of 70 percent to represent fine grained feldspar. For the 'glass' component we used a telescopic spectrum of a pyroclastic glass present on the Aristarchus plateau which is characterized by a strong smooth band centered at 1.07 microns. In addition to exhibiting the glass band this spectrum is very red and has a low albedo. On the assumption that the dark component and the red component are agglutinates, which is reasonable but not necessarily true, we sought a dark red component. To derive its properties we modelled the spectrum of an Apollo 16 soil (16xxx) and assumed the dark red component to comprise 60 percent of the soil, appropriate to agglutinate abundance in mature soil. We adjusted the albedo and slope of a straight line

  19. Mixing model analysis of telescopic lunar spectra

    NASA Technical Reports Server (NTRS)

    Lucey, Paul G.; Clark, Beth C.; Hawke, B. Ray

    1993-01-01

    We have analyzed very high quality reflectance spectra of the lunar surface from the University of Hawaii lunar spectral data collection using a spectral mixing model. The spectra analyzed are those of 45 mare sites and 75 highland sites. The spectra were selected on the basis of very high signal to noise ratios based on error bars and point to point scatter, and on quality of removal of telluric water bands. The spectral mixing model used 7 components, not all of which were used in each fit. Four of the components were mineral spectra of the orthopyroxene, a clinopyroxene, an olivine and an anorthite, measured at the Brown University's RELAB. All of the minerals were 45-90 micron splits. Lunar soil contains other components which have the effect of reddening and darkening the soil as well as reducing spectral contrast. In addition, lunar soil contains spectral neutral bright material (likely very fine grained feldspar) which serves to reduce spectral contrast and brighten soils. Early attempts to fit many of the spectra pointed out the need for a component which has a very broad smooth absorption feature centered near 1.1 microns. Glass is a good candidate for this component. For the bright component we used a flat reflectance of 70 percent to represent fine grained feldspar. For the 'glass' component we used a telescopic spectrum of a pyroclastic glass present on the Aristarchus plateau which is characterized by a strong smooth band centered at 1.07 microns. In addition to exhibiting the glass band this spectrum is very red and has a low albedo. On the assumption that the dark component and the red component are agglutinates, which is reasonable but not necessarily true, we sought a dark red component. To derive its properties we modelled the spectrum of an Apollo 16 soil (16xxx) and assumed the dark red component to comprise 60 percent of the soil, appropriate to agglutinate abundance in mature soil. We adjusted the albedo and slope of a straight line

  20. 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.

  1. 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.

  2. Near-Infrared Spectra of Supernovae

    NASA Astrophysics Data System (ADS)

    Gerardy, C. L.; Fesen, R. A.; Hoflich, P.; Nomoto, K.; Garnavich, P. M.; Jha, S.; Challis, P. M.; Kirshner, R. P.; Wheeler, J. C.; Sakai, S.

    2001-12-01

    We present results from a survey of the near-infrared properties of all types of supernovae. Near-infrared spectra of the subluminous Type Ia SN 1999by taken 5 days before to two weeks after maximum light have been analysed using self-consistent SN Ia explosion models. The data generally agree with 1D delayed-detonation models, indicate a near Chandrasekhar-mass WD progenitor, and show low yield of iron-peak elements confined to the innermost layers of the ejecta. This puts strong constraints on the mixing of large iron blobs into the outer layers due to Rayleigh-Taylor instabilities during the deflagration phase. NIR spectra of Type IIP SNe are relatively line-free during the plateau phase, showing largely hydrogen emission with only a handful of other lines, mostly in the 1-1.2 micron region. After the plateau phase, Type IIP spectra become much richer, showing many overlapping emission features throughout the near-infrared. It appears that CO emission is a common feature of core-collapse supernovae, as several detections of first overtone CO emission near 2.3 microns have been made, including SN 1998S (IIn), SN 1999em, SN 1999gi (IIP) and SN 2000ew (Ic). Finally, we find that Type IIn supernovae often exhibit extraordinary infrared excesses at late times. This is probably thermal emission from hot dust, most likely in the dense circumstellar gas surrounding the progenitor star. The infrared luminosity can reach 1041-42 erg s-1, and can last for several years. A possible scenario is that the dust emission is an ``infrared echo'' powered not by the flash of the SN explosion, but rather by UV/X-ray emission from the strong shock interaction with the dense circumstellar material.

  3. 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.

  4. 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.

  5. 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).

  6. Techniques for classifying acoustic resonant spectra

    SciTech Connect

    Roberts, R.S.; Lewis, P.S.; Chen, J.T.; Vela, O.A.

    1995-12-31

    A second-generation nondestructive evaluation (NDE) system that discriminates between different types of chemical munitions is under development. The NDE system extracts features from the acoustic spectra of known munitions, builds templates from these features, and performs classification by comparing features extracted from an unknown munition to a template library. Improvements over first-generation feature extraction template construction and classification algorithms are reported. Results are presented on the performance of the system and a large data set collected from surrogate-filled munitions.

  7. 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.

  8. Quantitative Analyses of Planetary Reflectance Spectra

    NASA Technical Reports Server (NTRS)

    Johnson, P. E.

    1985-01-01

    The development of a set of quantitative models to analyze planetary reflectance spectra as a function of microscopic and macroscopic mineral mixtures, particle size, and illumination geometry is considered. The approach has been to simplify more sophisticated algorithms to include the smallest number of parameters possible, consistent with being able to use them to produce useful results. This means that they should be able to model the data to within the accuracy obtainable by laboratory, telescopic, and space instrumentation (roughly 1%). The algorithms are ideally given in terms of parameters that are directly measureable (such as spectral reflectance or particle size).

  9. Video spectra of Leonids and other meteors

    NASA Astrophysics Data System (ADS)

    Borovička, Jiří

    2001-11-01

    Video spectra of 33 meteors of medium brightness (+1 to -1 mag) were compared. The intensity of the main meteoric emissions of Mg, Na, Fe, and atmospheric emissions of N2, O, N were studied. The Na/Mg ratio is different in different meteors, showing variations in Na abundance. Moreover, much earlier ablation of Na during the atmospheric entry than of other elements observed in some Leonids and one Orionid, Quadrantid and Leo Minorid evidences fragile structure of those meteoroids. One sporadic meteor was completely deficient in sodium. The strength of atmospheric emission increases with increasing meteor velocity. Taurids are notable by the near-absence of O and N emissions.

  10. 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.

  11. 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.

  12. 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.

  13. GENERAL RELATIVISTIC EFFECTS ON NONLINEAR POWER SPECTRA

    SciTech Connect

    Jeong, Donghui; Gong, Jinn-Ouk; Noh, Hyerim; Hwang, Jai-chan E-mail: jgong@lorentz.leidenuniv.nl E-mail: jchan@knu.ac.kr

    2011-01-20

    The nonlinear nature of Einstein's equation introduces genuine relativistic higher order corrections to the usual Newtonian fluid equations describing the evolution of cosmological perturbations. We study the effect of such novel nonlinearities on the next-to-leading order matter and velocity power spectra for the case of a pressureless, irrotational fluid in a flat Friedmann background. We find that pure general relativistic corrections are negligibly small over all scales. Our result guarantees that, in the current paradigm of standard cosmology, one can safely use Newtonian cosmology even in nonlinear regimes.

  14. 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).

  15. 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.

  16. SIMULATION OF PARTICLE SPECTRA AT RHIC.

    SciTech Connect

    KAHANA,D.E.; KAHANA,S.H.

    2001-09-04

    A purely hadronic simulation is performed of the recently reported data from PHOBOS at energies of {radical}s = 56, 130 GeV using the relativistic heavy ion cascade LUCIFER which had previously given a good description of the NA49 inclusive spectra at {radical}s = 17.2 GeV/A. The results compare well with these early measurements at RHIC and indeed successfully predict the increase in multiplicity now seen by PHOBOS and the other RHIC detectors at the nominal maximum energy of {radical}s = 200 GeV/A, suggesting that evidence for quark-gluon matter remains elusive.

  17. Hilbert transform: Applications to atomic spectra

    NASA Astrophysics Data System (ADS)

    Whittaker, Kate A.; Keaveney, James; Hughes, Ifan G.; Adams, Charles S.

    2015-03-01

    In many areas of physics, the Kramers-Kronig relations are used to extract information about the real part of the optical response of a medium from its imaginary counterpart. In this paper we discuss an alternative but mathematically equivalent approach based on the Hilbert transform. We apply the Hilbert transform to transmission spectra to find the group and refractive indices of a Cs vapor and thereby demonstrate how the Hilbert transform allows indirect measurement of the refractive index, group index, and group delay while avoiding the use of complicated experimental setups.

  18. 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.

  19. 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.

  20. Uncertainty Quantification on Prompt Fission Neutrons Spectra

    SciTech Connect

    Talou, P. Madland, D.G.; Kawano, T.

    2008-12-15

    Uncertainties in the evaluated prompt fission neutrons spectra present in ENDF/B-VII.0 are assessed in the framework of the Los Alamos model. The methodology used to quantify the uncertainties on an evaluated spectrum is introduced. We also briefly review the Los Alamos model and single out the parameters that have the largest influence on the calculated results. Using a Kalman filter, experimental data and uncertainties are introduced to constrain model parameters, and construct an evaluated covariance matrix for the prompt neutrons spectrum. Preliminary results are shown in the case of neutron-induced fission of {sup 235}U from thermal up to 15 MeV incident energies.

  1. 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.

  2. 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 ...

  3. 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.

  4. Identifying Minerals from Their Infra-red Spectra.

    ERIC Educational Resources Information Center

    Paterson, W. G.

    1986-01-01

    Describes a British secondary school's use of a spectrometer to identify minerals. Discusses the origins of mineral spectra, the preparation of the specimen, the actual spectroscopic scanning, and the interpretation of the spectra. (TW)

  5. 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.

  6. 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.

  7. 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.

  8. Atomic Spectra Bibliography Databases at NIST

    NASA Astrophysics Data System (ADS)

    Kramida, Alexander

    2008-05-01

    NIST's Atomic Spectroscopy Data Center maintains three online 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] now includes about 11500 references, mostly for years 1967--2007. The NIST Atomic Transition Probability BD, v. 8.1 [http://physics.nist.gov/fvalbib] with its 7500 references mainly covers years 1964--2007. The NIST Spectral Line Broadening BD, v. 2.0 [http://physics.nist.gov/linebrbib] has 3670 references, mostly for 1978--2006. All three databases are maintained in a unified database management system that allows us to quickly update the contents. Updates become available to users on the next day. An automated Data Entry module makes it easy to enter and categorize the data. The system allows us to keep the contents of all BDs up to date. A number of enhancements made since last year greatly increased public usability of the databases. This work is supported in part by the Office of Fusion Energy Sciences of the U.S. Department of Energy and by the National Aeronautics and Space Administration.

  9. 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

  10. 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

  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. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Spectra of Cas A's Highest Velocity Ejecta

    NASA Astrophysics Data System (ADS)

    Fesen, Robert A.; Milisavljevic, Dan

    2010-08-01

    The young age and close distance of the Galactic supernova remnant Cassiopeia A (Cas A) make it perhaps our best case study and clearest look at the explosion dynamics of a core-collapse supernova (CCSN). Interestingly, Cas A exhibits two nearly opposing streams of high velocity ejecta or `jets' in its NE and SW regions racing outward at speeds more than twice that of the main shell. The nature of these jets, however, and their possible association with an aspherical supernova explosion mechanism is controversial. A handful of existing low-resolution spectra of outer knots in the NE jet display chemical abundances hinting at an origin from the S-Si-Ca- Ar rich layer deep inside the progenitor. If these abundances could be firmly established in both the NE and SW jets, it would be very strong evidence in support of a highly asymmetrical explosion engine for Cas A's progenitor and, in turn, for CCSNe in general. We request KPNO 4m telescope + MARS time to obtain high quality multi-object spectroscopy of Cas A's highest velocity ejecta to measure their nitrogen, sulfur, oxygen, calcium, and argon abundances. These spectra will be analyzed with the metal-rich shock models of J. Raymond and then compared to current sets of CCSN models paying particular attention to knot composition vs. ejection velocity and ejecta mixing.

  18. 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.

  19. Fourier transform spectra of quantum dots

    NASA Astrophysics Data System (ADS)

    Damian, V.; Ardelean, I.; Armăşelu, Anca; Apostol, D.

    2010-05-01

    Semiconductor quantum dots are nanometer-sized crystals with unique photochemical and photophysical properties that are not available from either isolated molecules or bulk solids. These nanocrystals absorb light over a very broad spectral range as compared to molecular fluorophores which have very narrow excitation spectra. High-quality QDs are proper to be use in different biological and medical applications (as fluorescent labels, the cancer treatment and the drug delivery). In this article, we discuss Fourier transform visible spectroscopy of commercial quantum dots. We reveal that QDs produced by Evident Technologies when are enlightened by laser or luminescent diode light provides a spectral shift of their fluorescence spectra correlated to exciting emission wavelengths, as shown by the ARCspectroNIR Fourier Transform Spectrometer. In the final part of this paper we show an important biological application of CdSe/ZnS core-shell ODs as microbial labeling both for pure cultures of cyanobacteria (Synechocystis PCC 6803) and for mixed cultures of phototrophic and heterotrophic microorganisms.

  20. Fourier transform spectra of quantum dots

    NASA Astrophysics Data System (ADS)

    Damian, V.; Ardelean, I.; Armăşelu, Anca; Apostol, D.

    2009-09-01

    Semiconductor quantum dots are nanometer-sized crystals with unique photochemical and photophysical properties that are not available from either isolated molecules or bulk solids. These nanocrystals absorb light over a very broad spectral range as compared to molecular fluorophores which have very narrow excitation spectra. High-quality QDs are proper to be use in different biological and medical applications (as fluorescent labels, the cancer treatment and the drug delivery). In this article, we discuss Fourier transform visible spectroscopy of commercial quantum dots. We reveal that QDs produced by Evident Technologies when are enlightened by laser or luminescent diode light provides a spectral shift of their fluorescence spectra correlated to exciting emission wavelengths, as shown by the ARCspectroNIR Fourier Transform Spectrometer. In the final part of this paper we show an important biological application of CdSe/ZnS core-shell ODs as microbial labeling both for pure cultures of cyanobacteria (Synechocystis PCC 6803) and for mixed cultures of phototrophic and heterotrophic microorganisms.

  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. 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

  3. 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.

  4. 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.

  5. 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

  6. 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

  7. Spatially Resolved Mid-IR Spectra from Meteorites; Linking Composition, Crystallographic Orientation and Spectra on the Micro-Scale

    NASA Astrophysics Data System (ADS)

    Stephen, N. R.

    2016-08-01

    IR spectroscopy is used to infer composition of extraterrestrial bodies, comparing bulk spectra to databases of separate mineral phases. We extract spatially resolved meteorite-specific spectra from achondrites with respect to zonation and orientation.

  8. Comparative analysis of characteristic electron energy loss spectra and inelastic scattering cross-section spectra of Fe

    NASA Astrophysics Data System (ADS)

    Parshin, A. S.; Igumenov, A. Yu.; Mikhlin, Yu. L.; Pchelyakov, O. P.; Zhigalov, V. S.

    2016-05-01

    The inelastic electron scattering cross section spectra of Fe have been calculated based on experimental spectra of characteristic reflection electron energy loss as dependences of the product of the inelastic mean free path by the differential inelastic electron scattering cross section on the electron energy loss. It has been shown that the inelastic electron scattering cross-section spectra have certain advantages over the electron energy loss spectra in the analysis of the interaction of electrons with substance. The peaks of energy loss in the spectra of characteristic electron energy loss and inelastic electron scattering cross sections have been determined from the integral and differential spectra. It has been shown that the energy of the bulk plasmon is practically independent of the energy of primary electrons in the characteristic electron energy loss spectra and monotonically increases with increasing energy of primary electrons in the inelastic electron scattering cross-section spectra. The variation in the maximum energy of the inelastic electron scattering cross-section spectra is caused by the redistribution of intensities over the peaks of losses due to various excitations. The inelastic electron scattering cross-section spectra have been analyzed using the decomposition of the spectra into peaks of the energy loss. This method has been used for the quantitative estimation of the contributions from different energy loss processes to the inelastic electron scattering cross-section spectra of Fe and for the determination of the nature of the energy loss peaks.

  9. 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

  10. 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.

  11. Infrared Spectra of Polycyclic Aromatic Hydrocarbons: Nitrogen Substitution

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W.; Arnold, James O. (Technical Monitor)

    1998-01-01

    The B3LYP/4-31G approach is used to compute the harmonic frequencies of substituted naphthalene, anthracene, and their cations. The substitutions include cyano (CN), aminio (NH2), imino (NH), and replacement of a CH group by a nitrogen atom. All unique sites are considered, namely 1 and 2 for naphthalene and 1, 2, and 9 for an'tracene, except for the imino, where only 2-iminonaphthalene is studied. The IR spectra of these substituted species are compared with those of the unsubstituted molecules. The addition of a CN group does not significantly affect the spectra except to add the CN stretching frequency. Replacing a CH group by N has only a small effect on the IR spectra. The addition of the NH2 group dramatically affects the neutral spectra, giving it much of the character of the cation spectra. However, the neutral 2-irrinonaphthalene spectra looks more like that of naphthalene than like the 2-aminonaphthalene spectra.

  12. New LRS spectra for 356 bright IRAS sources

    NASA Technical Reports Server (NTRS)

    Volk, Kevin; Cohen, Martin

    1989-01-01

    The low-resolution spectra of all IRAS point sources with F(nu) (12 microns) greater than 40 Jy that were not included in the Atlas of Low-Resolution Spectra are presented. These have been classified into eight groups based upon the spectral morphology. Silicate emission spectra and red-continuum spectra associated with H II region sources form about 60 percent of this sample. All types of spectra in the LRS Atlas are represented in the sample except for emission-line sources. The sample is used to test a recent classification scheme for IRAS sources based on broadband colors. The spectra is used to test a recent classification scheme for IRAS sources based on broadband colors. The spectra are consistent with the classifications from the colors in most cases.

  13. Comparison between MAFAGS-OS spectra and Kurucz-ODF spectra

    NASA Astrophysics Data System (ADS)

    Zhang, Jiannan; Luo, Ali; Song, Yihan; Zuo, Fang

    2011-12-01

    Grids of theoretical stellar spectra are fundamental for estimating basic stellar parameters from photometric and spectroscopic data observed in large sky surveys such as SDSS, LAMOST, Gaia, etc. Do the different atmosphere models influence the parameters estimation? We compute the Lick indexes and uvby color indexes using the MAFAGS-OS grid of model atmospheres and fluxes provided by F. Grupp (personal comm.) and the Kurucz grids [1]. A spectrum comparison reveals the behavior of spectra from the MAFAGS and Kurucz grids. We find that using the (b-y) index, consistent effective temperatures can be determined from both the Kurucz and MAFAGS grids of theoretical spectra. The m1 index, together with color index, can be used to determine the metallicity of F- and G-type stars, but the measurements of the Kurucz and MAFAGS grids show systematic discrepancies for cool stars. The c1 indexes computed with both grids show small discrepancies for Teff < 6000 K, while for Teff > 6000 K, the c1 indexes agree well. The Lick indexes of the Kurucz grid and the MAFAGS grid tend to be in agreement for warm stars with temperatures above 5000 K, while for cool stars with temperatures ranging from 4000 K to 5000 K, the difference of Lick indexes for both models is apparently large. We also compare the MAFAGS spectrum and Kurucz spectrum of the same temperature, surface gravity, and metallicity using a correlation coefficient for the complete spectrum. For warm stars, the MAFAGS and Kurucz spectra are almost the same, while for cool stars below 5000 K, there are some discrepancies between the MAFAGS and Kurucz spectra that induce internal discrepancies in the parameters determination.

  14. Spectra of particulate backscattering in natural waters.

    PubMed

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

    2009-08-31

    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 (b(b)) 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(b) approximately lambda(-n), where n is a constant between 0.4 and 1.0. However, the weak spectral features in b(b)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. PMID:19724619

  15. Infrared Spectra of High Pressure Carbon Monoxide

    SciTech Connect

    Evans, W J; Lipp, M J; Lorenzana, H E

    2001-09-21

    We report infrared (IR) spectroscopic measurements of carbon monoxide (CO) at high pressures. Although CO is one of the simplest heteronuclear diatomic molecules, it displays surprisingly complex behavior at high pressures and has been the subject of several studies [1-5]. IR spectroscopic studies of high pressures phases of CO provide data complementing results from previous studies and elucidating the nature of these phases. Though a well-known and widely utilized diagnostic of molecular systems, IR spectroscopy presents several experimental challenges to high pressure diamond anvil cell research. We present measurements of the IR absorption bands of CO at high pressures and experimentally illustrate the crucial importance of accurate normalization of IR spectra specially within regions of strong absorptions in diamond.

  16. IR spectra of irradiated organic materials

    NASA Astrophysics Data System (ADS)

    Strazzulla, G.; Calcagno, L.; Foti, A. M.; Massimino, P.; Spinella, F.

    1988-05-01

    Infrared spectra of organic molecules, including frozen gases, aliphatic and aromatic polymers, complex molecules, and biological compounds are presented, and their changes due to fast ion bombardment are described. It is found that (1) the targets lose hydrogen preferentially and the stoichiometric H/C decreases; (2) the materials become more absorbing and their color changes from white to black as the ion dose increases; (3) the crystallinity, if present initially, is destroyed, and bombarded material is amorphous although microcrystallinity cannot be ruled out; (4) the skeletal vibrations are changed, indicating the occurrence of cross-lining and the formation of tridimensional networks. The astrophysical and space mission implications of these findings are addressed.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Spectra of functionalized operators arising from hypersurfaces

    NASA Astrophysics Data System (ADS)

    Hayrapetyan, Gurgen; Promislow, Keith

    2015-06-01

    Functionalized energies, such as the Functionalized Cahn-Hilliard, model phase separation in amphiphilic systems, in which interface production is limited by the competition for surfactant phase, which wets the interface. This is in contrast to classical phase-separating energies, such as the Cahn-Hilliard, in which interfacial area is energetically penalized. In binary amphiphilic mixtures, interfaces are characterized not by single layers, which separate domains of phase A from those of phase B via a heteroclinic connection, but by bilayers, which divide the domain of the dominant phase, A, via thin layers of phase B formed by homoclinic connections. Evaluating the second variation of the functionalized energy at a bilayer interface yields a functionalized operator. We characterize the center-unstable spectra of functionalized operators and obtain resolvent estimates to the operators associated with gradient flows of the functionalized energies. This is an essential step to a rigorous reduction to a sharp-interface limit.

  2. 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.

  3. 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.

  4. Oxidation of carbynes: Signatures in infrared spectra

    SciTech Connect

    Cinquanta, E. E-mail: p.rudolf@rug.nl; Manini, N.; Caramella, L.; Onida, G.; Ravagnan, L.; Milani, P.; Rudolf, P. E-mail: p.rudolf@rug.nl

    2014-06-28

    We report and solidly interpret the infrared spectrum of both pristine and oxidized carbynes embedded in a pure-carbon matrix. The spectra probe separately the effects of oxidation on sp- and on sp{sup 2}-hybridized carbon, and provide information on the stability of the different structures in an oxidizing atmosphere. The final products are mostly short end-oxidized carbynes anchored with a double bond to sp{sup 2} fragments, plus an oxidized sp{sup 2} amorphous matrix. Our results have important implications for the realization of carbyne-based nano-electronics devices and highlight the active participation of carbynes in astrochemical reactions where they act as carbon source for the promotion of more complex organic species.

  5. Spectra of Microwave Oscillations in Ferrospinel Films

    NASA Astrophysics Data System (ADS)

    Badrtdinov, G. S.; Mitlina, L. A.; Meleshko, N. V.

    2016-09-01

    The absorption spectra of ferrospinel single crystal films obtained by the method of chemical transport reactions are considered. It is demonstrated that along with a homogeneous resonance, additional absorption peaks corresponding to exchange spin modes localized in the surface layer are observed in the absorption spectrum investigated with an EPR spectrometer in the case of perpendicular orientation of the film with respect to an external static magnetic field. Resonant interaction of magnetostatic oscillations with exchange spin modes in the surface layer is detected in the case of tangent magnetization. The width of the magnetostatic layer and the ranges of existence of the surface and volume modes depend on the relationship between the constants of uniaxial surface anisotropy and crystallographic magnetic anisotropy. The wave numbers of the magnetostatic and exchange spin modes, the parameters of inhomogeneous exchange, and the effective magnon masses are calculated.

  6. X ray spectra of cataclysmic variables

    NASA Technical Reports Server (NTRS)

    Patterson, Joseph; Halpern, Jules

    1990-01-01

    X ray spectral parameters of cataclysmic variables observed with the 'Einstein' imaging proportional counter were determined by fitting an optically thin, thermal bremsstrahlung spectrum to the raw data. Most of the sources show temperatures of order a few keV, while a few sources exhibit harder spectra with temperatures in excess of 10 keV. Estimated 0.1 to 3.5 keV luminosities are generally in the range from 10(exp 30) to 10(exp 32) erg/sec. The results are consistent with the x rays originating in a disk/white dwarf boundary layer of non-magnetic systems, or in a hot, post-shock region in the accretion column of DQ Her stars, with a negligible contribution from the corona of the companion. In a few objects column densities were found that are unusually high for interstellar material. It was suggested that the absorption occurs in the system itself.

  7. 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.

  8. IIB soliton spectra with all fluxes activated

    NASA Astrophysics Data System (ADS)

    Evslin, Jarah

    2003-05-01

    Building upon an earlier proposal for the classification of fluxes, a sequence is proposed which generalizes the AHSS by computing type IIB string theory's group of conserved RR and also NS charges, which is conjectured to be a K-theory of dual pairs. As a test of this proposal, the formalism of Maldacena, Moore and Seiberg ( arxiv:hep-th/0108100) is applied to classify D-branes, NS5-branes, F-strings and their dielectric counterparts in IIB compactified on a 3-sphere with both NS and RR background fluxes. The soliton spectra on the 3-sphere are then compared with the output of the sequence, as is the baryon spectrum in Witten's non- spinc example, AdS 5× RP5. The group of conserved charges is seen to change during Brown-Teitelboim-like phase transitions which change the effective cosmological constant.

  9. 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.

  10. 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.

  11. Satellite spectra for helium-like titanium

    SciTech Connect

    Bely-Dubac, F.; Faucher, P.; Steeman-Clark, L.; Dubau, J.; Cammy-Val, C.; Bitter, M.; Hill, K.W.; von Goeler, S.

    1982-06-01

    Wavelengths and atomic parameters for both dielectronic and inner-shell satellite lines of the type ls/sup 2/ nl - 1s2l' nl, with n = 2, 3, and 4, have been calculated for Ti XX. The atomic data were calculated in a multiconfiguration intermediate coupling scheme and are compared with previous results for n = 2. The intensities of the higher n satellites are derived from these data, and thus an estimate of the contribution of the unresolved dielectronic satellites to the resonance line is obtained. Direct excitation rates are also given for the resonance, intercombination and forbidden lines for He-like titanium. Cascades and the effect of resonances for these lines are not considered in this paper. These results are used to fit an experimental soft x-ray spectrum from the PDX (Poloidal Divertor Experiment) tokamak discharge. Good agreement is obtained between computed and observed spectra.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. Universality of vibrational spectra of globular proteins.

    PubMed

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

    2016-02-23

    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. 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.

  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. [Raman spectra of monkey cerebral cortex tissue].

    PubMed

    Zhu, Ji-chun; Guo, Jian-yu; Cai, Wei-ying; Wang, Zu-geng; Sun, Zhen-rong

    2010-01-01

    Monkey cerebral cortex, an important part in the brain to control action and thought activities, is mainly composed of grey matter and nerve cell. In the present paper, the in situ Raman spectra of the cerebral cortex of the birth, teenage and aged monkeys were achieved for the first time. The results show that the Raman spectra for the different age monkey cerebral cortex exhibit most obvious changes in the regions of 1000-1400 and 2800-3000 cm(-1). With monkey growing up, the relative intensities of the Raman bands at 1313 and 2885 cm(-1) mainly assigned to CH2 chain vibrational mode of lipid become stronger and stronger whereas the relative intensities of the Raman bands at 1338 and 2932 cm(-1) mainly assigned to CH3 chain vibrational mode of protein become weaker and weaker. In addition, the two new Raman bands at 1296 and 2850 cm(-1) are only observed in the aged monkey cerebral cortex, therefore, the two bands can be considered as a character or "marker" to differentiate the caducity degree with monkey growth In order to further explore the changes, the relative intensity ratios of the Raman band at 1313 cm(-1) to that at 1338 cm(-1) and the Raman band at 2885 cm(-1) to that at 2 932 cm(-1), I1313/I1338 and I2885/I2932, which are the lipid-to-protein ratios, are introduced to denote the degree of the lipid content. The results show that the relative intensity ratios increase significantly with monkey growth, namely, the lipid content in the cerebral cortex increases greatly with monkey growth. So, the authors can deduce that the overmuch lipid is an important cause to induce the caducity. Therefore, the results will be a powerful assistance and valuable parameter to study the order of life growth and diagnose diseases.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. Title: Near-UV behaviour of observed TNO reflectance spectra

    NASA Astrophysics Data System (ADS)

    Seccull, Tom; Fraser, Wesley Cristopher; Izawa, Matthew; Brown, Michael E.

    2016-10-01

    Observed spectra provide the best diagnostics of the surface compositions of Trans-Neptunian Objects (TNOs). We have observed the spectra of 7 TNOs, from across almost the full range of dynamical classes, using the VLT's X-Shooter spectrograph. Compared to the 5 targets in our sample which exhibit linear spectra in the UV-optical range, two of of our targets show highly unusual spectral behaviour, whereby their reflectance decreases sharply at wavelengths below ~440nm. Those same objects exhibit typically unremarkable spectra in the optical and near-IR spectral regions. In these regions where available, our observed spectra of the targets are in agreement with spectra or photometry available in the literature. Using a different solar analogue to produce our reflectance spectra does not remove the UV decrease exhibited by the two targets. Further, it appears that neither reducing the spectra with different pipelines, nor using drastically different parameters in those pipelines changes this general behaviour. Based on laboratory spectra of complex hydrocarbons it is plausible that the near-UV behaviour is the result of a surface coating of organic substances on the TNOs which exhibit it. The spectra of organics are also consistent in having a general red slope similar to that observed in the spectra of many TNOs. While laboratory spectra of some silicate substances also show a decrease in reflectance in the near-UV spectral region that is in principle consistent with our observations, those silicates do not exhibit a red slope consistent with our optical spectra. Hence, the hypothesis that silicates are present seems less likely than the hypothesis that this UV decrease is due to the presence of organics on the surfaces of these objects.

  9. 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.

  10. A Comparison of SIR-B Directional Ocean Wave Spectra with Aircraft Scanning Radar Spectra.

    PubMed

    Beal, R C; Monaldo, F M; Tilley, D G; Irvine, D E; Walsh, E J; Jackson, F C; Hancock, D W; Hines, D E; Swift, R N; Gonzalez, F L; Lyzenga, D R; Zambresky, L F

    1986-06-20

    Directional ocean wave spectra derived from Shuttle Imaging Radar-B (SIR-B) L-band imagery collected off the coast of southern Chile on 11 and 12 October 1984 were compared with independent spectral estimates from two airborne scanning radars. In sea states with significant wave heights ranging from 3 to 5 meters, the SIR-B-derived spectra at 18 degrees and 25 degrees off nadir yielded reasonable estimates of wavelengths, directions, and spectral shapes for all wave systems encountered, including a purely azimuth-traveling system. A SIR-B image intensity variance spectrum containing predominantly range-traveling waves closely resembles an independent aircraft estimate of the slope variance spectrum. The prediction of a U.S. Navy global spectral ocean wave model on 11 October 1984 exhibited no significant bias in dominant wave number but contained a directional bias of about 30 degrees espect to the mean of the aircraft and spacecraft estimates.

  11. A Comprehensive Investigation Into Modeling Supernovae Spectra

    NASA Astrophysics Data System (ADS)

    Hillier, Desmond

    Supernovae are a rich source of information. By studying their light curves and spectra we gain insights into stellar evolution, the nature of the progenitor star, surface abundances at the time of the explosion, whether previous mass-loss episodes have occurred, the physics of the explosion including the amount and type of elements synthesized, and whether the explosion has produced significant mixing between shells of different chemical composition. To maximize the information that can be gleaned from observations of supernovae it is essential that we have the necessary spectroscopic tools. To this end, we are developing a code, CMFGEN, capable of modeling supernova light curves and spectra. The code is currently being used, to study core-collapse supernovae as well as those arising from the nuclear detonation of a White Dwarf star. We wish to extend CMFGEN's capabilities by developing a procedure to handle non-monotonic velocity flows so that we can treat shock breakout and the interaction of supernova ejecta with circumstellar material. We will also investigate magnetar-powered SNe, and explore the connection between Type Ib and Type Ic supernovae and those supernovae associated with long-duration gamma-ray bursters. Through detailed studies of individual supernova, and through the construction of model grids, we are able to infer deficiencies in our modeling, in our atomic data, and in the progenitor models, and hence make refinements so that we can improve our understanding of all SNe classes. Previous (IUE), current (HST, Chandra, GALEX), and future NASA missions (James Webb Telescope) do/will provide a wealth of data on supernovae. The proposed research is related to strategic subgoal 3D: "Discover the origin, structure, evolution, and destiny of the universe, and search for Earth-like planets." Supernovae are inherently coupled to the evolution of the universe and life: They can trigger star formation and they provide the raw materials (e.g., oxygen

  12. Theoretical Raman spectra of carbonate minerals

    NASA Astrophysics Data System (ADS)

    Bobocioiu, E.; Caracas, R.

    2011-12-01

    The Raman spectra of the majority of MeCO3 minerals, with Me=alkali elements, calc-alkali elements or combinations thereof, are determined using density functional perturbation theory in the ABINIT implementation. We consider more than a dozen different minerals, most of them with rhombohedral, i.e. calcite-like, or orthorhombic, i.e. aragonite-like, structures [1]. We start with the experimental structure and perform two distinct structural relaxations: one at experimental density, i.e. experimental volume, and one at theoretical 0GPa pressure. During these structural relaxations we minimize the energy, the residual forces on the atoms and the non-hydrostatic stresses on the unit cell. Consequently in the end we obtain to distinct sets of data. We find that the relative intensities of the major Raman peaks are in good agreement with respect to experiment. The positions of the peaks are consistently shifted relative to the experiment. As a general rule, the best agreement between theory and experiment is obtained for the calcualtions performed at experimental density. We find that all spectra are dominated, as expected, by the stretching modes of the planar CO3 groups. Their theoretical frequency varies from as low as 1066 in paralstonite [BaCa(CO3)2] up to high as 1113 cm-1 in eitelite [Na2Mg(CO3)2]. The low-frequency modes are dominated by the heavy cations. Their degeneracy is directly determined by the symmetry of the structure. We performed a detailed comparative study to be able to identify identification trends. Finally we discuss C and O isotope fractionation patterns. We compute log(β) functions based on the vibrational information contained in the Brillouin zone center. Though not complete, this information is already enough to give us a reasonable estimation of the partitioning. Reference: Caracas, R., Bobocioiu, E. (2011) The WURM project - a freely available web-based repository of computed physical data for minerals, American Mineralogist, vol. 96

  13. Model Atmospheres and X-Ray Spectra of Bursting Neutron Stars: Hydrogen-Helium Comptonized Spectra

    NASA Astrophysics Data System (ADS)

    Madej, J.; Joss, P. C.; Różańska, A.

    2004-02-01

    Compton scattering plays a crucial role in determining the structure of the atmosphere of an X-ray burster and its theoretical spectrum. Our paper presents a description of the plane-parallel model atmosphere of a very hot neutron star and its theoretical flux spectrum of outgoing radiation. Our model equations take into account all bound-free and free-free monochromatic opacities relevant to hydrogen-helium chemical composition and take into account the effects of Compton scattering of radiation in thermal plasma with fully relativistic thermal velocities. We use Compton scattering terms in the equation of transfer, which precisely describe photon-electron energy and momentum exchange for photons with initial energies exceeding the electron rest mass of 511 keV. Model atmosphere equations are solved with the variable Eddington factors technique. The grid of H-He model atmospheres and flux spectra is computed on a dense mesh of 107K<=Teff<=3×107K and a surface gravity of logg. In many cases, the assumed logg approached the critical gravity loggcr, i.e., the Eddington limit. We confirm that H-He spectra of X-ray bursters deviate from blackbody spectra and discuss their shapes. The table of color to effective temperature ratios shows that theoretical values of Tc/Teff do not exceed 1.9 in H-He atmospheres in hydrostatic and radiative equilibrium.

  14. [Raman spectra of fossil dinosaurs from different regions].

    PubMed

    Yang, Qun; Wang, Yi-lin

    2007-12-01

    Raman microscopic spectra in the higher wave number region were obtained from 7 fossil dinosaurs specimens from different regions. The specimens of fossil dinosaurs are different parts of bone. The Raman spectra of fossil dinosaurs indicate the high similarity among peak positions of different fossil dinosaurs; but important differences exist in the spectral peak figures. In the wave number region of 1000-1800 cm(-1) the Raman spectra of the same bone part fossils from different regions are very similar, example similarities between spectra of Lufeing backbone head and Yua nmou backbone head; Lufeng limb bone and Wuding limb bone. There are relations between the same bone part spectra of different fossil dinosaurs. The characteristic does not relate to regions. Raman spectra of fossil dinosaurs cannot be used to distinguish fossil source, although the part of bone can be used as an indicator to narrow the range of possible geographical origins.

  15. A novel computational method for comparing vibrational circular dichroism spectra.

    PubMed

    Shen, Jian; Zhu, Chengyue; Reiling, Stephan; Vaz, Roy

    2010-08-01

    A novel method, SimIR/VCD, for comparing experimental and calculated VCD (vibrational circular dichroism) spectra is developed, based on newly defined spectra similarities. With computationally optimized frequency scaling and shifting, a calculated spectrum can be easily identified to match an observed spectrum, which leads to an unbiased molecular chirality assignment. The time-consuming manual band-fitting work is greatly reduced. With (1S)-(-)-alpha-pinene as an example, it demonstrates that the calculated VCD similarity is correlated with VCD spectra matching quality and has enough sensitivity to identify variations in the spectra. The study also compares spectra calculated using different DFT methods and basis sets. Using this method should facilitate the spectra matching, reduce human error and provide a confidence measure in the chiral assignment using VCD spectroscopy.

  16. 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.

  17. 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

  18. Quantifying in vivo MR spectra with circles

    NASA Astrophysics Data System (ADS)

    Gabr, Refaat E.; Ouwerkerk, Ronald; Bottomley, Paul A.

    2006-03-01

    Accurate and robust quantification of in vivo magnetic resonance spectroscopy (MRS) data is essential to its application in research and medicine. The performance of existing analysis methods is problematic for in vivo studies where low signal-to-noise ratio, overlapping peaks and intense artefacts are endemic. Here, a new frequency-domain technique for MRS data analysis is introduced wherein the circular trajectories which result when spectral peaks are projected onto the complex plane, are fitted with active circle models. The use of active contour strategies naturally allows incorporation of prior knowledge as constraint energy terms. The problem of phasing spectra is eliminated, and baseline artefacts are dealt with using active contours-snakes. The stability and accuracy of the new technique, CFIT, is compared with a standard time-domain fitting tool, using simulated 31P data with varying amounts of noise and 98 real human chest and heart 31P MRS data sets. The real data were also analyzed by our standard frequency-domain absorption-mode technique. On the real data, CFIT demonstrated the least fitting failures of all methods and an accuracy similar to the latter method, with both these techniques outperforming the time-domain approach. Contrasting results from simulations argue that performance relative to Cramer-Rao Bounds may not be a suitable indicator of fitting performance with typical in vivo data such as these. We conclude that CFIT is a stable, accurate alternative to the best existing methods of fitting in vivo data.

  19. 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).

  20. Pentacene Derivatives: Electronic Structure and Spectra

    NASA Astrophysics Data System (ADS)

    Netusil, Ross; Ilie, Carolina; Kane, Thorin; Damkaci, Fehmi

    2013-03-01

    The variation in composition and structure of the substituent groups of pentacene compounds promises a broad range of electronic structures and behaviors and provides a vast and alluring field of inquiry with avenues of exploration. These include the development of synthetic schema, the process of design for novel derivatives and, in order to identify those hypothesized compounds which demonstrate the desired behavior, the identification and refinement of computational tools that make accurate predictions about the electronic behavior of theoretical compounds. Two computational techniques and six pentacene derivatives are here examined. One technique was used to predict the vibrational spectra of the compounds, in order to both acquire data about the optical conductivity of the compounds and to establish a pool of theoretical data against which experimental data will be compared. The molecular orbital energy level diagram of the same six compounds was derived using a second approach, with the same goals of discerning between valid and invalid predictive schema by comparison with pending experimental data and between hypothesized compounds which show promise and those which present little potential for use in organic semiconductor technology.

  1. 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.

  2. 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.

  3. 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.

  4. Inflationary power spectra with quantum holonomy corrections

    SciTech Connect

    Mielczarek, Jakub

    2014-03-01

    In this paper we study slow-roll inflation with holonomy corrections from loop quantum cosmology. It was previously shown that, in the Planck epoch, these corrections lead to such effects as singularity avoidance, metric signature change and a state of silence. Here, we consider holonomy corrections affecting the phase of cosmic inflation, which takes place away from the Planck epoch. Both tensor and scalar power spectra of primordial inflationary perturbations are computed up to the first order in slow-roll parameters and V/ρ{sub c}, where V is a potential of the scalar field and ρ{sub c} is a critical energy density (expected to be of the order of the Planck energy density). Possible normalizations of modes at short scales are discussed. In case the normalization is performed with use of the Wronskian condition applied to adiabatic vacuum, the tensor and scalar spectral indices are not quantum corrected in the leading order. However, by choosing an alternative method of normalization one can obtain quantum corrections in the leading order. Furthermore, we show that the holonomy-corrected equations of motion for tensor and scalar modes can be derived based on effective background metrics. This allows us to show that the classical Wronskian normalization condition is well defined for the cosmological perturbations with holonomy corrections.

  5. Radio spectra of High Frequency Peakers

    NASA Astrophysics Data System (ADS)

    Dallacasa, D.; Orienti, M.

    2016-02-01

    New radio spectra of High Frequency Peakers (HFP) obtained from the Jansky Very Large Array (JVLA) show that variability is common among this class of sources. A subsample of sources have been observed with a nearly continuous spectral sampling between 1 and 10 GHz. The observed HFP sources were previously classified as F (flat), H (HFP profile with little or no flux density variability) and V (variable, but preserving a peaked spectrum). In general, sources classified as V and H show a decrease of the flux density measured in the optically thin part of the spectrum, while there is a moderate increment in the optically thick region, resulting into a progressive shift of the spectral peak to lower frequencies. This is consistent with the idea of an expanding bubble of radio plasma. The sources with an F classification instead show substantial variability, both in spectral shape and in time evolution. In these HFP sources an irregular production of energy is best observed since the radio emission is dominated by recently generated relativistic plasma, and the contribution of mini lobes, in which old plasma accumulates, is marginal if not absent at all, given the short radiative life of electrons in strong magnetic fields (tens of mG) found in these objects.

  6. 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

  7. 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.

  8. 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.

  9. 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)

  10. Determination of primary energy spectra from Maket Ani data

    NASA Astrophysics Data System (ADS)

    Chilingarian, A. A.; Gharagyozyan, G. V.; Ghazaryan, S. S.; Hovsepyan, G. G.; Melkumyan, L. G.; Sokhoyan, S. H.; Ter-Antonyan, S. V.; Vardanyan, A. A.

    The unfolding of the primary energy spectra from size spectra measured by MAKET ANI installation is performed. The nonparametric regression method was used for estimation of energy of each detected shower. Simple method of the unfolding of size spectra was introduced as robust alternative to event-by-event analysis of EAS data. Both methods agree within experimental and methodical errors. The ways to utilize a priori knowledge for physical inference are discussed.

  11. 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.

  12. Near infrared reflection spectra of artificial cumulus clouds.

    PubMed

    Plummer, W T

    1969-10-01

    Reflection spectra are presented for artificial cumulus clouds with a progression of droplet sizes, including sizes common in natural clouds, over the wavelength range from 1.0 micro to 2.4 micro. A correction is made for gaseous absorption. The spectra show reflectivity minima at 1.16 micro, 1.41 micro, and 1.92micro which deepen as the droplets become larger and are in good agreement with reflection spectra of terrestrial clouds.

  13. Resonant Compton scattering and gamma-ray burst continuum spectra

    NASA Technical Reports Server (NTRS)

    Baring, M. G.

    1995-01-01

    The Thomson limit of resonant inverse Compton scattering in the strong magnetic fields of neutron stars is considered as a mechanism for producing gamma-ray burst continuum spectra. Photon production spectra and electron cooling rates are presented using the full magnetic Thomson cross-section. Model emission spectra are obtained as self-consistent solutions of a set of photon and electron kinetic equations, displaying spectral breaks and other structure at gamma-ray energies.

  14. Double-Resonance Facilitated Decomposion of Emission Spectra

    NASA Astrophysics Data System (ADS)

    Kato, Ryota; Ishikawa, Haruki

    2016-06-01

    Emission spectra provide us with rich information about the excited-state processes such as proton-transfer, charge-transfer and so on. In the cases that more than one excited states are involved, emission spectra from different excited states sometimes overlap and a decomposition of the overlapped spectra is desired. One of the methods to perform a decomposition is a time-resolved fluorescence technique. It uses a difference in time evolutions of components involved. However, in the gas-phase, a concentration of the sample is frequently too small to carry out this method. On the other hand, double-resonance technique is a very powerful tool to discriminate or identify a common species in the spectra in the gas-phase. Thus, in the present study, we applied the double-resonance technique to resolve the overlapped emission spectra. When transient IR absorption spectra of the excited state are available, we can label the population of the certain species by the IR excitation with a proper selection of the IR wavenumbers. Thus, we can obtain the emission spectra of labeled species by subtracting the emission spectra with IR labeling from that without IR. In the present study, we chose the charge-transfer emission spectra of cyanophenyldisilane (CPDS) as a test system. One of us reported that two charge-transfer (CT) states are involved in the intramolecular charge-transfer (ICT) process of CPDS-water cluster and recorded the transient IR spectra. As expected, we have succeeded in resolving the CT emission spectra of CPDS-water cluster by the double resonance facilitated decomposion technique. In the present paper, we will report the details of the experimental scheme and the results of the decomposition of the emission spectra. H. Ishikawa, et al., Chem. Phys. Phys. Chem., 9, 117 (2007).

  15. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    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/r2 rule due to changes in the neutron spectra.

  17. 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.

  18. A practical method for the analysis of meteor spectra

    NASA Astrophysics Data System (ADS)

    Dubs, Martin; Schlatter, Peter

    2015-08-01

    The analysis of meteor spectra (photographic, CCD or video recording) is complicated by the fact that spectra obtained with objective gratings are curved and have a nonlinear dispersion. In this paper it is shown that with a simple image transformation the spectra can be linearized in such a way that individual spectra over the whole image plane are parallel and have a constant, linear dispersion. This simplifies the identification and measurement of meteor spectral lines. A practical method is given to determine the required image transformation.

  19. Computing the Balmer Wavelengths With a Hand Calculator

    ERIC Educational Resources Information Center

    Sidran, Miriam

    1977-01-01

    Outlines a problem concerning the computation of hydrogen spectral line wavelength in a general physics class which is appropriate for computations on calculators with 8 significant digits of accuracy. (SL)

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. Scaling and universality in microbial size spectra

    NASA Astrophysics Data System (ADS)

    Giometto, A.; Altermatt, F.; Carrara, F.; Maritan, A.; Rinaldo, A.

    2012-12-01

    In this work, focus is placed on the mass distribution of individual organisms of a given species in laboratory communities of protists. The relevance of the work pertains the importance of the variability of body size - currently neglected by most theoretical approaches or simply synthesized by the species' mean body mass - in a broad spectrum of issues ranging from the interpretation of Kleiber's law and of intertwined macroecological laws, to the ubiquity of broad, often scale-free community size spectra in nature. Here, it is shown experimentally that single species' size distributions for thirteen different protists' species spanning four orders of magnitude exhibit certain regularities well captured by a finite-size scaling distribution. In fact, once suitably rescaled, they collapse onto the same distribution regardless of the vast differences in their size. This is found to apply over four orders of magnitude in mass, thus suggesting the existence of an underlying universal mechanism shaping the size distribution of such organisms. In addition, the theoretical origins of the experimental result are addressed and a simple model of cell growth and division is shown to account for the main features of the observed universality. Environmental forcing of various kinds is shown not to affect the scaling result. It is claimed that this work provides a significant contribution to a number of open problems in ecology, like for instance the long-lasting dispute on linked scaling exponents in macroecological empirical relations. In fact, the characterization of the fluctuations in the mass of organisms enters directly several ecological scaling laws and the embedded account for whole size distributions (as opposed to mean body mass alone) acts as the explanatory variable for a number of current debates.

  6. 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).

  7. 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

  8. 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.

  9. 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

  10. Infrared spectra of gas-phase polycyclic aromatic hydrocarbon molecules

    SciTech Connect

    Zhang, Keqing; Guo, B.; Bernath, P.F.

    1995-12-31

    Recording the spectra of gas-phase polycyclic aromatic hydrocarbon molecules is of great astronomical interest. Infrared spectra of gas-phase naphthalene, pyrene, and chrysene were obtained in absorption and emission. The band positions and relative intensities were measured and compared with theoretical calculations. These data will be compared to the astronomical observations of the unidentified infrared emission bands.

  11. Vibrational spectra of corticosteroid hormones in the terahertz range

    NASA Astrophysics Data System (ADS)

    Cherkasova, O. P.; Nazarov, M. M.; Sapozhnikov, D. A.; Man'kova, A. A.; Fedulova, E. V.; Volodin, V. A.; Minaeva, V. A.; Minaev, B. F.; Baryshnikov, G. V.

    2010-11-01

    The terahertz time-domain and Raman spectra of corticosteroid hormones in the region of low-frequency infrared vibrations have been measured. On the ground of quantum chemical calculations of the frequencies and normal modes the assignments of vibrational bands in the THz-spectra are performed.

  12. 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.

  13. Vibrational spectra of the two hydrates of strontium oxalate.

    PubMed

    D'Antonio, Maria C; Torres, María M; Palacios, Daniel; González-Baró, Ana C; Baran, Enrique J

    2015-02-25

    The infrared and Raman spectra of the two hydrates of strontium oxalate, SrC2O4⋅H2O and SrC2O4⋅2H2O, were recorded and discussed on the basis of their structural peculiarities and in comparison with the spectra of the related calcium oxalates and other previously investigated metallic oxalates.

  14. 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.

  15. [Saltation behavior in excitation spectra of fluorescent molecules].

    PubMed

    Miao, Di; Xu, Yi-zhuang; Yang, Jun; Xu, Zhen-hua; Wu, Jin-guang

    2004-05-01

    Excitation spectra are commonly used to study relationship between molecular structure of fluorescent substances and energy transfer during the fluorescence process. It is generally taken for granted that the excitation spectrum of the sample is equivalent to its absorption spectrum, even a copy of the latter. However, exceptions have been found in many cases. Considering various factors that affect the excitation spectra of solution comprehensively, a model has been established to study the behavior of the excitation spectra. After analyzing the model mathematically, including introducing catastrophe theory, we came into the following conclusions: As far as the topological properties are concerned, the excitation spectra are the same as its absorption spectra, provided the concentration of the substance is below a threshold. However, when the concentration is beyond the threshold, the excitation spectra undergo a series of topological saltation, leading to significant a deviation from the absorption spectra. Comparative studies of both excitation and absorption spectra of naphthalene dissolved in n-hexane confirmed the above hypothesis.

  16. 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.

  17. 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).

  18. Peptide identification by database search of mixture tandem mass spectra.

    PubMed

    Wang, Jian; Bourne, Philip E; Bandeira, Nuno

    2011-12-01

    In high-throughput proteomics the development of computational methods and novel experimental strategies often rely on each other. In certain areas, mass spectrometry methods for data acquisition are ahead of computational methods to interpret the resulting tandem mass spectra. Particularly, although there are numerous situations in which a mixture tandem mass spectrum can contain fragment ions from two or more peptides, nearly all database search tools still make the assumption that each tandem mass spectrum comes from one peptide. Common examples include mixture spectra from co-eluting peptides in complex samples, spectra generated from data-independent acquisition methods, and spectra from peptides with complex post-translational modifications. We propose a new database search tool (MixDB) that is able to identify mixture tandem mass spectra from more than one peptide. We show that peptides can be reliably identified with up to 95% accuracy from mixture spectra while considering only a 0.01% of all possible peptide pairs (four orders of magnitude speedup). Comparison with current database search methods indicates that our approach has better or comparable sensitivity and precision at identifying single-peptide spectra while simultaneously being able to identify 38% more peptides from mixture spectra at significantly higher precision.

  19. Newmark design spectra considering earthquake magnitudes and site categories

    NASA Astrophysics Data System (ADS)

    Li, Bo; Xie, Wei-Chau; Pandey, M. D.

    2016-09-01

    Newmark design spectra have been implemented in many building codes, especially in building codes for critical structures. Previous studies show that Newmark design spectra exhibit lower amplitudes at high frequencies and larger amplitudes at low frequencies in comparison with spectra developed by statistical methods. To resolve this problem, this study considers three suites of ground motions recorded at three types of sites. Using these ground motions, influences of the shear-wave velocity, earthquake magnitudes, source-to-site distances on the ratios of ground motion parameters are studied, and spectrum amplification factors are statistically calculated. Spectral bounds for combinations of three site categories and two cases of earthquake magnitudes are estimated. Site design spectrum coefficients for the three site categories considering earthquake magnitudes are established. The problems of Newmark design spectra could be resolved by using the site design spectrum coefficients to modify the spectral values of Newmark design spectra in the acceleration sensitive, velocity sensitive, and displacement sensitive regions.

  20. Experimental Investigation on Terahertz Spectra of Amphetamine Type Stimulants

    NASA Astrophysics Data System (ADS)

    Sun, Jin-Hai; Shen, Jing-Ling; Liang, Lai-Shun; Xu, Xiao-Yu; Liu, Hai-Bo; Zhang, Cun-Lin

    2005-12-01

    The spectral absorption features of three amphetamine-type stimulants (ATS) belonging to illicit drugs have been studied with terahertz (THz) time-domain spectroscopy (THz-TDS) and the characteristic absorption spectra (fingerprint spectra) are obtained in the range from 0.2 to 2.5 THz. Fingerprint spectra of illicit drugs in terahertz band are bases to detect and to inspect nondestructively illicit drugs with terahertz technique. With fingerprint spectra of illicit drugs and strong penetrability for cloths, paper bags and leathered or plastic luggage terahertz technique would be better than other techniques in illicit drugs detection and inspection. Thus, this work would contribute to the building of corresponding fingerprint spectra database of illicit drugs and provide experimental bases for using of terahertz detection apparatus in drugs nondestructive detection and inspection in the future.

  1. 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.

  2. 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.

  3. 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.

  4. New low-resolution spectrometer spectra for IRAS sources

    NASA Technical Reports Server (NTRS)

    Volk, Kevin; Kwok, Sun; Stencel, R. E.; Brugel, E.

    1991-01-01

    Low-resolution spectra of 486 IRAS point sources with F sub nu(12 microns) in the range 20-40 Jy are presented. This is part of an effort to extract and classify spectra that were not included in the Atlas of Low-Resolution Spectra and represents an extension of the earlier work by Volk and Cohen which covers sources with F sub nu(12 microns) greater than 40 Jy. The spectra have been examined by eye and classified into nine groups based on the spectral morphology. This new classification scheme is compared with the mechanical classification of the Atlas, and the differences are noted. Oxygen-rich stars of the asymptotic giant branch make up 33 percent of the sample. Solid state features dominate the spectra of most sources. It is found that the nature of the sources as implied by the present spectral classification is consistent with the classifications based on broad-band colors of the sources.

  5. 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})

  6. 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

  7. 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.

  8. 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.

  9. Reference solar spectra: how do they compare in the UV?

    NASA Astrophysics Data System (ADS)

    Gueymard, C.

    Reference spectra covering all (or nearly all) the solar spectrum and integrating to at least 95% of the solar constant are needed in a variety of disciplines. Due to current experimental limitations these spectra are not monolithic but are rather composites that need to be assembled from a mix of space measurements, ground observatory measurements, and solar models. Depending on the sources of data used in each waveband and various scaling factors, these reference spectra may differ substantially. The focus is here on those historic spectra that have reached standard or pseudo-standard status [ASTM, Colina, Kurucz, Smith & Gottlieb, Thekaekara, and Wehrli]. The UV part of each of these spectra are compared to that of a recently published reference spectrum (Gueymard, 2004), to a UV spectrum measured at the Mauna Loa Observatory with a Brewer spectrophotometer (Gröbner and Kerr, 2001), and to the latest measured data from the SORCE satellite with the SIM and SOLSTICE instruments. In particular, it is found that the Gueymard and Gröbner spectra are in almost perfect agreement over the whole spectral range of the latter (295--355 nm), at their common resolution of 0.5 nm. In comparison, the older Wehrli spectrum shows noticeable differences. The relationship between the experimental wavelength accuracy and the absolute accuracy of these spectra is discussed in detail. In the UV, it is argued that wavelength accuracy is the dominant source of error in the most recent spectra, although absolute calibration generally becomes the dominant factor when considering relaxed resolutions (e.g., > 5 nm). The process of deriving reference spectra is now being standardized by ISO (Tobiska and Nusinov, 2000; ISO, 2002). This initiative opens the door to the development of more dependable and intercomparable spectra. In particular, the derivation of the recent Gueymard spectrum and how it respects the ISO guidelines are discussed in detail.

  10. Component spectra extraction from terahertz measurements of unknown mixtures.

    PubMed

    Li, Xian; Hou, D B; Huang, P J; Cai, J H; Zhang, G X

    2015-10-20

    The aim of this work is to extract component spectra from unknown mixtures in the terahertz region. To that end, a method, hard modeling factor analysis (HMFA), was applied to resolve terahertz spectral matrices collected from the unknown mixtures. This method does not require any expertise of the user and allows the consideration of nonlinear effects such as peak variations or peak shifts. It describes the spectra using a peak-based nonlinear mathematic model and builds the component spectra automatically by recombination of the resolved peaks through correlation analysis. Meanwhile, modifications on the method were made to take the features of terahertz spectra into account and to deal with the artificial baseline problem that troubles the extraction process of some terahertz spectra. In order to validate the proposed method, simulated wideband terahertz spectra of binary and ternary systems and experimental terahertz absorption spectra of amino acids mixtures were tested. In each test, not only the number of pure components could be correctly predicted but also the identified pure spectra had a good similarity with the true spectra. Moreover, the proposed method associated the molecular motions with the component extraction, making the identification process more physically meaningful and interpretable compared to other methods. The results indicate that the HMFA method with the modifications can be a practical tool for identifying component terahertz spectra in completely unknown mixtures. This work reports the solution to this kind of problem in the terahertz region for the first time, to the best of the authors' knowledge, and represents a significant advance toward exploring physical or chemical mechanisms of unknown complex systems by terahertz spectroscopy.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. LET spectra measurements from the STS-35 CPDs

    NASA Technical Reports Server (NTRS)

    1995-01-01

    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.

  16. 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.

  17. 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.

  18. 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.

  19. Invariant Spectra in N-Coupled Standard Maps

    NASA Astrophysics Data System (ADS)

    Livadiotis, George

    This paper examines the evolution of the dynamical spectra of stretching numbers in a system of N-coupled Standard Maps. It is found that the convergence rate of the spectra to their invariant forms is independent of the dimensionality 2N and the nonlinearity/coupling parameters. This rate is impressively faster than one could predict on the basis of ergodicity. This effect is probably associated with the manifold of the maximum Lyapunov exponent along which the main stretching occurs. It seems that dynamical spectra depend mainly on the dramatically smaller subspace defined by this unstable manifold.

  20. 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.

  1. Photoemission spectra of charge density wave states in cuprates

    NASA Astrophysics Data System (ADS)

    Tu, Wei-Lin; Chen, Peng-Jen; Lee, Ting-Kuo

    Angle-resolved photoemission spectroscopy(ARPES) experiments have reported many exotic properties of cuprates, such as Fermi arc at normal state, two gaps at superconducting state and particle-hole asymmetry at the antinodal direction. On the other hand, a number of inhomogeneous states or so-called charge density waves(CDW) states have also been discovered in cuprates by many experimental groups. The relation between these CDW states and ARPES spectra is unclear. With the help of Gutzwiller projected mean-field theory, we can reproduce the quasiparticle spectra in momentum space. The spectra show strong correspondence to the experimental data with afore-mentioned exotic features in it.

  2. 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.

  3. Stretched-exponential Doppler spectra in underwater acoustic communication channels.

    PubMed

    van Walree, P A; Jenserud, T; Otnes, R

    2010-11-01

    The theory of underwater sound interacting with the sea surface predicts a Gaussian-spread frequency spectrum in the case of a large Rayleigh parameter. However, recent channel soundings reveal more sharply peaked spectra with heavier tails. The measured Doppler spread increases with the frequency and differs between multipath arrivals. The overall Doppler spectrum of a broadband waveform is the sum of the spectra of all constituent paths and frequencies, and is phenomenologically described by a stretched or compressed exponential. The stretched exponential also fits well to the broadband spectrum of a single propagation path, and narrowband spectra summed over all paths.

  4. Primary Cosmic-Ray Spectra in the Knee Region

    NASA Astrophysics Data System (ADS)

    Ter-Antonyan, Samvel V.; Biermann, P. L.

    2003-07-01

    Using EAS inverse approach and KASCADE EAS data the primary energy spectra for different primary nuclei at energies 1015 - 1017 eV are obtained in the framework of multi-comp onent model of primary cosmic ray origin and QGSJET and SIBYLL interaction models. The rigidity-dep endent behavior of spectra is the same for two interaction models. The extrap olation of the obtained primary spectra in a 1017 - 1018 eV energy range displays a presence of the extragalactic component of primary cosmic rays.

  5. 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.

  6. 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..

  7. 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.

  8. 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.

  9. 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.

  10. 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).

  11. 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.

  12. 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.

  13. 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.

  14. Predicting Infrared Spectra of Nerve Agents Using Density Functional Theory

    NASA Astrophysics Data System (ADS)

    Zhang, Y.-P.; Wang, H.-T.; Zheng, W.-P.; Sun, C.; Bai, Y.; Guo, X.-D.; Sun, H.

    2016-09-01

    Vibration frequencies of four nerve agents and two simulators are calculated using B3LYP coupled with ten basis sets. To evaluate the accuracy of calculated spectra, root mean square error (RMSE) and weighted cross-correlation average (WCCA) are considered. The evaluation shows that B3LYP/6-311+g(d,p) performs best in predicting infrared spectra, and polarization functions are found to be more important than diffusion functions in spectra simulation. Moreover, B3LYP calculation underestimates frequencies related to the P atom. The WCCA metric derives 1.008 as a unique scaling factor for calculated frequencies. The results indicate that the WCCA metric can identify six agents based on calculated spectra.

  15. Depth profiling code for analyzing ERD-TOF spectra

    NASA Astrophysics Data System (ADS)

    Mathot, G.; Terwagne, G.; Bodart, F.

    2001-07-01

    A computer program calculating depth profiles of light elements in surface layer of various materials from experimental ERD-TOF spectra has been developed. The program, which is able to identify the recoil particles, makes multi-element profiling by sorting the spectra by mass. The interactive spectrum synthesis compare the real recoils spectra with simulated spectra of the assumed target. The program is also able to calculate the atomic concentration ratios without any a priori assumption of the composition of an unknown target. The stopping power used in the analysis package respect the Alegria [1] format and can be easily upgraded and modified by the user. It can be calculated for any particle target combination and beam energy between 100 keV and 15 MeV. The calculation takes also into account for the straggling, the energy loss in the carbon foils of the start and the stop detectors and the entry window of the particle detector.

  16. Coherent multidimensional optical spectra measured using incoherent light

    NASA Astrophysics Data System (ADS)

    Turner, Daniel B.; Arpin, Paul C.; McClure, Scott D.; Ulness, Darin J.; Scholes, Gregory D.

    2013-08-01

    Four-wave mixing measurements can reveal spectral and dynamics information that is hidden in linear spectra by the interactions among light-absorbing molecules and with their environment. Coherent multidimensional optical spectroscopy is an important variant of four-wave mixing because it resolves a map of interactions and correlations between absorption bands. Previous coherent multidimensional optical spectroscopy measurements have used femtosecond pulses with great success, and it may seem that femtosecond pulses are necessary for such measurements. Here we present coherent two-dimensional electronic spectra measured using incoherent light. The spectra of model molecular systems using broadband spectrally incoherent light are similar but not identical to those expected from measurements using femtosecond pulses. Specifically, the spectra show particular sensitivity to long-lived intermediates such as photoisomers. The results will motivate the design of similar experiments in spectral ranges where femtosecond pulses are difficult to produce.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Spatial and temporal power spectra of the geomagnetic field

    SciTech Connect

    McLeod, M.G.

    1996-02-10

    This report explores the statistical properties of the geomagnetic field. This research tries to determine the gaussian coefficient covariance from magnetic field measurements of spatial and temporal power spectra and give a theoretical explanation for the nature of these covariances.

  2. 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.

  3. On the calibration of the IRAS low-resolution spectra

    NASA Technical Reports Server (NTRS)

    Volk, Kevin; Cohen, Martin

    1989-01-01

    The need for corrections to the LRS spectra based on a study of a number of normal stars observed by IRAS is discussed. The spectra of bright stars, such as alpha CMa, were found to be inconsistent with blackbody sources, this effect being generally observed in sources earlier than about K3. An attempt is made to correct the LRS spectra by changing the blackbody calibration temperature for Alpha Tau, assumed to be a 10,000-K blackbody source for the original LRS flux calibration. It is found that an anomalously low color temperature must be assumed for alpha Tau to produce reasonable results for earlier-type stars. Corrections based on a set of stars with well-determined effective temperatures are examined, as are the resulting color temperatures for 72 stars with Atlas spectra.

  4. LET spectra measurements on LDEF: variations with shielding and location.

    PubMed

    Benton, E V; Frank, A L; Csige, I; Frigo, L A; Benton, E R

    1996-11-01

    LET spectra measurements made with passive plastic nuclear track detectors (PNTDs) were found to depend on detector orientation, shielding and experiment location. LET spectra were measured at several locations on LDEF as part of the P0006 LETSME experiment (Benton and Parnell, 1984), the P0004 Seeds in Space experiment (Parks and Alston, 1984), the A00l5 Free Flyer Biostacks and the M0004 Fiber Optics Data Link experiment (Taylor, 1984). Locations included the east, west and Earth sides of the LDEF satellite. The LET spectra measured with PNTDs deviated significantly from calculations, especially for high LET particles (LET infinity H2O > or = 100 keV/micrometer). At high LETs, short-range inelastic secondary particles produced by trapped proton interactions with the nuclei of the detector were found to be the principal contributor to LET spectra. At lower LETs, the spectra appeared to be due to short-range, inelastic and stopping primary protons, with primary GCR particles making a smaller contribution. The dependence of LET spectra on detector orientation and shielding was studied using the four orthogonal stacks in the P0006 experiment. Both measurements of total track density and LET spectra showed a greater number of particles arriving from the direction of space than from Earth. Measurements of LET spectra in CR-39 PNTD on the east (leading) and west (trailing) sides of LDEF showed a higher rate of production at the west side. This was caused by a larger flux of trapped protons on the west side as predicted by the east/west trapped proton anisotropy in the South Atlantic Anomaly (SAA). Track density measured in CR-39 PNTDs increased as a function of shielding depth in the detector stack. A similar measurement made in a thick stack of CR-39 interspersed with layers of Al and exposed to 154 MeV protons at a ground-based accelerator showed a similar result, indicating that a significant fraction of the particle events counted were from secondaries and that the

  5. Optical absorption spectra of pairs of small metal particles

    NASA Astrophysics Data System (ADS)

    Quinten, M.; Kreibig, U.; Schönauer, D.; Genzel, L.

    1985-06-01

    The influence of plasma resonance coupling in small Au particle pairs on their optical properties was calculated including retardation effects. The latter prove to be important for sizes above 15 nm. For pairs of smaller particles a Maxwell-Garnett formula is derived and absorption spectra are calculated explicitly. Comparison with optical absorption spectra measured on aggregated Au particle hydrosols, gives good agreement concerning the splitting up of the dipolar single-particle plasma resonance band.

  6. 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.

  7. Fourier transform Raman and IR spectra of snake skin

    NASA Astrophysics Data System (ADS)

    Barry, B. W.; Williams, A. C.; Edwards, H. G. M.

    1993-06-01

    The Fourier transform (FT) Raman and IR spectra of the shed dorsal skin of the snake Elaphe obsoleta (American black rat snake) are reported. Vibrational spectroscopic assignments are proposed for the first time. Although good quality Raman spectra were obtained from the hinge regions using an FT Raman microscope, the dorsal scale regions fluoresced even with 1064 nm IR excitation. This was ascribed to pigmentation markings on the scales.

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

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  9. 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.

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

    NASA Astrophysics Data System (ADS)

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

    1988-08-01

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

  11. EUV Emission Spectra and Gain in Polyacetal Capillary Discharge

    NASA Astrophysics Data System (ADS)

    Vrbova, M.; Vrba, P.; Jancarek, A.; Bobrova, N. A.; Sasorov, P. V.; Limpouch, J.; Pina, L.; Nadvornikova, L.; Fojtik, A.

    2002-11-01

    Experimental and computer studies of polyacetal capillary discharge are reported. Time resolved spectra in the wavelength region 3 - 25 nm are measured. Space-time dependences of plasma electron density and temperature are calculated by means of MHD code. Time profiles of selected lithium-, helium- and hydrogen-like carbon and oxygen ion populations and time resolved spectra are evaluated by means of the FLY code. Gain factors for a capillary initially either evacuated or filled by polyacetal vapors are calculated.

  12. Seasonal Variations of Stratospheric Age Spectra in GEOSCCM

    NASA Technical Reports Server (NTRS)

    Li, Feng; Waugh, Darryn; Douglass, Anne R.; Newman, Paul A.; Pawson, Steven; Stolarski, Richard S.; Strahan, Susan E.; Nielsen, J. Eric

    2011-01-01

    There are many pathways for an air parcel to travel from the troposphere to the stratosphere, each of which takes different time. The distribution of all the possible transient times, i.e. the stratospheric age spectrum, contains important information on transport characteristics. However, it is computationally very expensive to compute seasonally varying age spectra, and previous studies have focused mainly on the annual mean properties of the age spectra. To date our knowledge of the seasonality of the stratospheric age spectra is very limited. In this study we investigate the seasonal variations of the stratospheric age spectra in the Goddard Earth Observing System Chemistry Climate Model (GEOSCCM). We introduce a method to significantly reduce the computational cost for calculating seasonally dependent age spectra. Our simulations show that stratospheric age spectra in GEOSCCM have strong seasonal cycles and the seasonal cycles change with latitude and height. In the lower stratosphere extratropics, the average transit times and the most probable transit times in the winter/early spring spectra are more than twice as old as those in the summer/early fall spectra. But the seasonal cycle in the subtropical lower stratosphere is nearly out of phase with that in the extratropics. In the middle and upper stratosphere, significant seasonal variations occur in the sUbtropics. The spectral shapes also show dramatic seasonal change, especially at high latitudes. These seasonal variations reflect the seasonal evolution of the slow Brewer-Dobson circulation (with timescale of years) and the fast isentropic mixing (with timescale of days to months).

  13. Raman spectra of oxalates in lichen encrustations on Renaissance frescoes

    NASA Astrophysics Data System (ADS)

    Edwards, H. G. M.; Farwell, D. W.; Seaward, M. R. D.

    The vibrational Raman spectra of lichen encrustations on biodeteriorated Renaissance frescoes have been recorded using a laser Raman microprobe. The major chemical species identified in the encrustations is calcium oxalate. Other vibrational features in the Raman spectra have been assigned to fragments of the substratum incorporated from the biodeterioration process and to organic by-products of lichen metabolism such as erythrin, lecanoric acid and meso-erythritol.

  14. Spectra of clinical CT scanners using a portable Compton spectrometer

    SciTech Connect

    Duisterwinkel, H. A.; Abbema, J. K. van; Kawachimaru, R.; Paganini, L.; Graaf, E. R. van der; Brandenburg, S.; Goethem, M. J. van

    2015-04-15

    Purpose: Spectral information of the output of x-ray tubes in (dual source) computer tomography (CT) scanners can be used to improve the conversion of CT numbers to proton stopping power and can be used to advantage in CT scanner quality assurance. The purpose of this study is to design, validate, and apply a compact portable Compton spectrometer that was constructed to accurately measure x-ray spectra of CT scanners. Methods: In the design of the Compton spectrometer, the shielding materials were carefully chosen and positioned to reduce background by x-ray fluorescence from the materials used. The spectrum of Compton scattered x-rays alters from the original source spectrum due to various physical processes. Reconstruction of the original x-ray spectrum from the Compton scattered spectrum is based on Monte Carlo simulations of the processes involved. This reconstruction is validated by comparing directly and indirectly measured spectra of a mobile x-ray tube. The Compton spectrometer is assessed in a clinical setting by measuring x-ray spectra at various tube voltages of three different medical CT scanner x-ray tubes. Results: The directly and indirectly measured spectra are in good agreement (their ratio being 0.99) thereby validating the reconstruction method. The measured spectra of the medical CT scanners are consistent with theoretical spectra and spectra obtained from the x-ray tube manufacturer. Conclusions: A Compton spectrometer has been successfully designed, constructed, validated, and applied in the measurement of x-ray spectra of CT scanners. These measurements show that our compact Compton spectrometer can be rapidly set-up using the alignment lasers of the CT scanner, thereby enabling its use in commissioning, troubleshooting, and, e.g., annual performance check-ups of CT scanners.

  15. Classifying Spectra Based on DLS and Rough Set

    NASA Astrophysics Data System (ADS)

    Qiu, Bo; Hu, Zhanyi; Zhao, Yongheng

    2003-01-01

    Until now, it is still difficult to identify different kinds of celestial bodies depending on their spectra, because it needs a lot of astronomers" manual work of measuring, marking and identifying, which is generally very hard and time-consuming. And with the exploding spectral data from all kinds of telescopes, it is becoming more and more urgent to find a thoroughly automatic way to deal with such a kind of problem. In fact, when we change our viewpoint, we can find that it is a traditional problem in pattern recognition field when considering the whole process of dealing with spectral signals: filtering noises, extracting features, constructing classifiers, etc. The main purpose for automatic classification and recognition of spectra in LAMOST (Large Sky Area Multi-Object Fibre Spectroscopic Telescope) project is to identify a celestial body"s type only based on its spectrum. For this purpose, one of the key steps is to establish a good model to describe all kinds of spectra and thus it will be available to construct some excellent classifiers. In this paper, we present a novel describing language to represent spectra. And then, based on the language, we use some algorithms to extract classifying rules from raw spectra datasets and then construct classifiers to identify spectra by using rough set method. Compared with other methods, our technique is more similar to man"s thinking way, and to some extent, efficient.

  16. Rogue wave spectra of the Kundu-Eckhaus equation.

    PubMed

    Bayındır, Cihan

    2016-06-01

    In this paper we analyze the rogue wave spectra of the Kundu-Eckhaus equation (KEE). We compare our findings with their nonlinear Schrödinger equation (NLSE) analogs and show that the spectra of the individual rogue waves significantly differ from their NLSE analogs. A remarkable difference is the one-sided development of the triangular spectrum before the rogue wave becomes evident in time. Also we show that increasing the skewness of the rogue wave results in increased asymmetry in the triangular Fourier spectra. Additionally, the triangular spectra of the rogue waves of the KEE begin to develop at earlier stages of their development compared to their NLSE analogs, especially for larger skew angles. This feature may be used to enhance the early warning times of the rogue waves. However, we show that in a chaotic wave field with many spectral components the triangular spectra remain as the main attribute as a universal feature of the typical wave fields produced through modulation instability and characteristic features of the KEE's analytical rogue wave spectra may be suppressed in a realistic chaotic wave field. PMID:27415263

  17. Turbulence spectra of the FIRE stratocumulus-topped boundary layers

    NASA Technical Reports Server (NTRS)

    Young, G. S.; Nucciarone, J. J.; Albrecht, Bruce A.

    1990-01-01

    There are at least four physical phenomena which contribute to the FIRE boundary layer turbulence spectra: boundary layer spanning eddies resulting from buoyant and mechanical production of turbulent kinetic energy (the microscale subrange); inertial subrange turbulence which cascades this energy to smaller scales; quasi-two dimensional mesoscale variations; and gravity waves. The relative contributions of these four phenomena to the spectra depend on the altitude of observation and variable involved (vertical velocity, temperature and moisture spectra are discussed). The physical origins of these variations in relative contribution are discussed. As expected from the theory (Kaimal et al., 1976), mixed layer scaling of the spectra (i.e., nondimensionalizing wavelength by Z(sub i) and spectral density by Z(sub i) and the dissipation rates) is successful for the microscale subrange and inertial subrange but not for the mesoscale subrange. The most striking feature of the normalized vertical velocity spectra is the lack of any significant mesoscale contribution. The spectral peak results from buoyant and mechanical production on scales similar to the boundary layer depth. The decrease in spectral density at larger scales results from the suppression of vertical velocity perturbations with large horizontal scales by the shallowness of the atmosphere. The spectral density also decreases towards smaller scales following the well known inertial subrange slope. There is a significant variation in the shape of the normalized spectra with height.

  18. Identification of THz absorption spectra of chemicals using neural networks

    NASA Astrophysics Data System (ADS)

    Shen, Jingling; Jia, Yan; Liang, Meiyan; Chen, Sijia

    2007-09-01

    Absorption spectra in the range from 0.2 to 2.6 THz of chemicals such as illicit drugs and antibiotics obtaining from Terahertz time-domain spectroscopy technique were identified successfully by artificial neural networks. Back Propagation (BP) and Self-Organizing Feature Map (SOM) were investigated to do the identification or classification, respectively. Three-layer BP neural networks were employed to identify absorption spectra of nine illicit drugs and six antibiotics. The spectra of the chemicals were used to train a BP neural network and then the absorption spectra measured in different times were identified by the trained BP neural network. The average identification rate of 76% was achieved. SOM neural networks, another important neural network which sorts input vectors by their similarity, was used to sort 60 absorption spectra from 6 illicit drugs. The whole network was trained by setting a 20×20 and a 16×16 grid, and both of them had given satisfied clustering results. These results indicate that it is feasible to apply BP and SOM neural networks model in the field of THz spectra identification.

  19. A COMPARISON OF GADRAS SIMULATED AND MEASURED GAMMA RAY SPECTRA

    SciTech Connect

    Jeffcoat, R.; Salaymeh, S.

    2010-06-28

    Gamma-ray radiation detection systems are continuously being developed and improved for detecting the presence of radioactive material and for identifying isotopes present. Gamma-ray spectra, from many different isotopes and in different types and thicknesses of attenuation material and matrixes, are needed to evaluate the performance of these devices. Recently, a test and evaluation exercise was performed by the Savannah River National Laboratory that required a large number of gamma-ray spectra. Simulated spectra were used for a major portion of the testing in order to provide a pool of data large enough for the results to be statistically significant. The test data set was comprised of two types of data, measured and simulated. The measured data were acquired with a hand-held Radioisotope Identification Device (RIID) and simulated spectra were created using Gamma Detector Response and Analysis Software (GADRAS, Mitchell and Mattingly, Sandia National Laboratory). GADRAS uses a one-dimensional discrete ordinate calculation to simulate gamma-ray spectra. The measured and simulated spectra have been analyzed and compared. This paper will discuss the results of the comparison and offer explanations for spectral differences.

  20. The Processing and Classification for the Spectra of Six Comets

    NASA Astrophysics Data System (ADS)

    Zhan, Xiang; Chen, Li

    2014-01-01

    In order to explore the relationship between comets and asteroids, the spectra of six comets, including 78P, C/2009 P1, 49P, C/2010 G2, C/2010 S1, and C/2011 F1, have been observed with the 2.16 m telescope at the Xinglong Observing Station of National Astronomical Observatories. At the same time, the spectra of some sun-like stars are also observed. The IRAF (Image Reduction and Analysis Facility) software is used to process the obtained spectra, and to obtain the relative reflectance spectra of the six comets. Then, they are compared with the 24 asteroid spectral types of the Bus-DeMeo taxonomy to derive the spectral distances of these comets. According to the order of the calculated spectral distances, the details of the reflectance spectra, as well as the results of the K-S test, the asteroid spectral types which are most close to the spectra of these comets are finally determined.

  1. LSD-based analysis of high-resolution stellar spectra

    NASA Astrophysics Data System (ADS)

    Tsymbal, V.; Tkachenko, A.; Van, Reeth T.

    2014-11-01

    We present a generalization of the method of least-squares deconvolution (LSD), a powerful tool for extracting high S/N average line profiles from stellar spectra. The generalization of the method is effected by extending it towards the multiprofile LSD and by introducing the possibility to correct the line strengths from the initial mask. We illustrate the new approach by two examples: (a) the detection of astroseismic signatures from low S/N spectra of single stars, and (b) disentangling spectra of multiple stellar objects. The analysis is applied to spectra obtained with 2-m class telescopes in the course of spectroscopic ground-based support for space missions such as CoRoT and Kepler. Usually, rather high S/N is required, so smaller telescopes can only compete successfully with more advanced ones when one can apply a technique that enables a remarkable increase in the S/N of the spectra which they observe. Since the LSD profiles have a potential for reconstruction what is common in all the spectral profiles, it should have a particular practical application to faint stars observed with 2-m class telescopes and whose spectra show remarkable LPVs.

  2. Cancer detection based on Raman spectra super-paramagnetic clustering

    NASA Astrophysics Data System (ADS)

    González-Solís, José Luis; Guizar-Ruiz, Juan Ignacio; Martínez-Espinosa, Juan Carlos; Martínez-Zerega, Brenda Esmeralda; Juárez-López, Héctor Alfonso; Vargas-Rodríguez, Héctor; Gallegos-Infante, Luis Armando; González-Silva, Ricardo Armando; Espinoza-Padilla, Pedro Basilio; Palomares-Anda, Pascual

    2016-08-01

    The clustering of Raman spectra of serum sample is analyzed using the super-paramagnetic clustering technique based in the Potts spin model. We investigated the clustering of biochemical networks by using Raman data that define edge lengths in the network, and where the interactions are functions of the Raman spectra's individual band intensities. For this study, we used two groups of 58 and 102 control Raman spectra and the intensities of 160, 150 and 42 Raman spectra of serum samples from breast and cervical cancer and leukemia patients, respectively. The spectra were collected from patients from different hospitals from Mexico. By using super-paramagnetic clustering technique, we identified the most natural and compact clusters allowing us to discriminate the control and cancer patients. A special interest was the leukemia case where its nearly hierarchical observed structure allowed the identification of the patients's leukemia type. The goal of this study is to apply a model of statistical physics, as the super-paramagnetic, to find these natural clusters that allow us to design a cancer detection method. To the best of our knowledge, this is the first report of preliminary results evaluating the usefulness of super-paramagnetic clustering in the discipline of spectroscopy where it is used for classification of spectra.

  3. Comparison of remotely sensed continental-shelf wave spectra with spectra computed by using a wave refraction computer model

    NASA Technical Reports Server (NTRS)

    Poole, L. R.

    1976-01-01

    An initial attempt was made to verify the Langley Research Center and Virginia Institute of Marine Science mid-Atlantic continental-shelf wave refraction model. The model was used to simulate refraction occurring during a continental-shelf remote sensing experiment conducted on August 17, 1973. Simulated wave spectra compared favorably, in a qualitative sense, with the experimental spectra. However, it was observed that most of the wave energy resided at frequencies higher than those for which refraction and shoaling effects were predicted, In addition, variations among the experimental spectra were so small that they were not considered statistically significant. In order to verify the refraction model, simulation must be performed in conjunction with a set of significantly varying spectra in which a considerable portion of the total energy resides at frequencies for which refraction and shoaling effects are likely.

  4. Comparison of strong-motion spectra with teleseismic spectra for three magnitude 8 subduction-zone earthquakes

    NASA Astrophysics Data System (ADS)

    Houston, Heidi; Kanamori, Hiroo

    1990-08-01

    A comparison of strong-motion spectra and teleseismic spectra was made for three Mw 7.8 to 8.0 earthquakes: the 1985 Michoacan (Mexico) earthquake, the 1985 Valparaiso (Chile) earthquake, and the 1983 Akita-Oki (Japan) earthquake. The decay of spectral amplitude with the distance from the station was determined, considering different measures of distance from a finite fault, and it was found to be different for these three events. The results can be used to establish empirical relations between the observed spectra and the half-space responses depending on the distance and the site condition, making it possible to estimate strong motions from source spectra determined from teleseismic records.

  5. ASERA: A spectrum eye recognition assistant for quasar spectra

    NASA Astrophysics Data System (ADS)

    Yuan, Hailong; Zhang, Haotong; Zhang, Yanxia; Lei, Yajuan; Dong, Yiqiao; Zhao, Yongheng

    2013-11-01

    Spectral type recognition is an important and fundamental step of large sky survey projects in the data reduction for further scientific research, like parameter measurement and statistic work. It tends out to be a huge job to manually inspect the low quality spectra produced from the massive spectroscopic survey, where the automatic pipeline may not provide confident type classification results. In order to improve the efficiency and effectiveness of spectral classification, we develop a semi-automated toolkit named ASERA, ASpectrum Eye Recognition Assistant. The main purpose of ASERA is to help the user in quasar spectral recognition and redshift measurement. Furthermore it can also be used to recognize various types of spectra of stars, galaxies and AGNs (Active Galactic Nucleus). It is an interactive software allowing the user to visualize observed spectra, superimpose template spectra from the Sloan Digital Sky Survey (SDSS), and interactively access related spectral line information. It is an efficient and user-friendly toolkit for the accurate classification of spectra observed by LAMOST (the Large Sky Area Multi-object Fiber Spectroscopic Telescope). The toolkit is available in two modes: a Java standalone application and a Java applet. ASERA has a few functions, such as wavelength and flux scale setting, zoom in and out, redshift estimation, spectral line identification, which helps user to improve the spectral classification accuracy especially for low quality spectra and reduce the labor of eyeball check. The function and performance of this tool is displayed through the recognition of several quasar spectra and a late type stellar spectrum from the LAMOST Pilot survey. Its future expansion capabilities are discussed.

  6. Biaxial shear/tension failure criteria of spectra single fibers

    NASA Astrophysics Data System (ADS)

    Sun, Jianzhuo

    An experimental study was conducted to develop the biaxial failure surface criteria of single Spectra 130d and 100d filaments in a torsion-tension environment. The cross-sectional profiles of single Spectra fibers were investigated using scanning electron microscopy and X-ray computed tomography. A pin-gripping method to fix the ends of a polyethylene single fiber was developed. Effects of pin diameter on failure stress for both Spectra 130d and 100d were characterized. It was found that the perturbed stress field effect can be neglected when the pin diameter is larger than 0.8 mm. Additionally, the effect of the sample's gage length on fiber tensile strength was investigated. The gage length of 5.5 mm was determined as an appropriate length for single fiber samples under stress-wave loading. A twisting apparatus was built for a single fiber to achieve specific degrees of shear strains. Quasi-static experiments were conducted using an MTS servo-hydraulic system to apply tensile loads on pre-twisted Spectra fibers. A tension Kolsky bar was employed to study the biaxial shear/tensile behavior of Spectra fibers at high strain rates. A decreasing trend of tensile strength, with increasing torsional strain, for Spectra fibers was observed. Furthermore, a torsional pendulum apparatus was developed to determine the torsional shear stresses in fibers at various levels of axial loading. The relationship between apparent shear stress and axial stress was discovered. Finally, a biaxial shear/tension failure criterion envelope of each of the Spectra fibers was established. Scanning electron microscopy images revealed the specific feature on the surface of twisted fibers and fracture surface of failure fibers.

  7. Alpha particle spectra and microdosimetry of radon daughters

    SciTech Connect

    Caswell, R.S.; Coyne, J.J.

    1992-12-31

    We are interested in understanding the physics of the process by which radon-daughter alpha particles irradiate cells, leading to the induction of cancer. We are focusing initially on two aspects: the alpha spectra incident upon cells, which are needed for input to biophysical models of cancer induction; and microdosimetric spectra and parameters which give information on radiation quality. Adapting an analytical method previously developed for neutron radiation, we have calculated the alpha-particle slowing-down spectra (the spectra incident upon cells) and, subsequently, the microdosimetric spectra and parameters for various cell nuclei or site diameters. Results will be presented from three modes of program operation. MODE 1 is for the thin, plane source of radon-daughter activity adjacent to the epithelium. MODE 2 is for the thick source layer (the mucous-serous layer) adjacent to the epithelium. MODE4 is for cylindrical airways of various radii, lined by the mucous-serous layer. MODE 1 is most useful for understanding the problem; MODE 4 is most anatomically relevant. MODE 3 is not discussed in this paper. Alpha-particle spectra and microdosimetric spectra and parameters are studied as a function of cell depth, {sup 218}Po/{sup 214}Po ratio, airway radius, and cell nucleus or the site size. Also available from the calculation is mean dose as a function of depth below the airway surface. The results described here are available on personal computer diskettes. We are beginning to compare our studies with the calculations of other workers and plan to extend the calculations to the nanometer target level.

  8. UV-IR Spectra of the Icy Saturnian Satellites

    NASA Astrophysics Data System (ADS)

    Hendrix, A. R.; Filacchione, G.; Schenk, P.; Clark, R. N.; Cuzzi, J. N.; Noll, K. S.; Spencer, J. R.

    2014-12-01

    Cassini's multi-instrument suite allows simultaneous observations of the icy satellites of Saturn over a wide range of wavelengths. We present composite UV-IR spectra (0.1-5 microns) of the leading and trailing hemispheres of the icy moons using data from Cassini supplemented with spectra from Hubble Space Telescope (STIS). We use data of Mimas, Enceladus, Tethys, Dione and Rhea from the Ultraviolet Imaging Spectrograph (UVIS), the Imaging Subsystem (ISS) and the Visual-Near Infrared Mapping Spectrometer (VIMS) taken during simultaneous measurements, or using similar observational geometries. The well-studied phase curve behaviors of the satellites are utilized to readily combine Earth-based STIS data with the Cassini datasets to create composite spectra. Focusing primarily on the UV-visible region so far, we find that the spectra of all satellites are bright and spectrally relatively flat at visible wavelengths longer than 500-600 nm; shortward of 500-600 nm the surfaces become absorbing with wavelength, resulting in reddish spectra. The satellites exhibit flattish-to-bowl-shaped spectra in the ~200-350 nm range and demonstrate the 165 nm water ice absorption edge, in varying strengths. These composite spectra are used to study the system-wide surface compositions of the satellites to understand large-scale exogenic effects (e.g., E-ring grain bombardment and radiolytic processing) at a variety of regolith sensing depths, and in particular to study implications for the presence and distribution of organics, ammonia, and other non-H2O-ice species in the system.

  9. Detecting and distinguishing metamorphic gradients of Unequilibrated (Type 3) Ordinary Chondrites using Infrared Reflectance Spectra.

    NASA Astrophysics Data System (ADS)

    Trivedi, M.; Smith, H. D.; Sears, D. W. G.

    2014-09-01

    We measure the IR reflectance spectra of fallen UOC to determine if Type 3 meteorites can be identified and classified using IR reflectance spectra and clinopyroxene abundance. Spectra was obtained from RELAB and taken on samples from SI and NHM.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  11. Secondary particle contribution to LET spectra on LDEF

    NASA Technical Reports Server (NTRS)

    Benton, E. R.; Benton, E. V.; Frank, A. L.; Frigo, L. A.; Csige, I.

    1996-01-01

    Four experiments utilizing passive detectors (P0006, P0004, A0015, M0004) were flown on LDEF to study the radiation environment. These experiments have been summarized in a companion paper (Benton et al., 1996). One of the experimental goals was to measure LET spectra at different locations and shielding depths with plastic nuclear track detectors (PNTD). It was found that the LET spectra extended well above the LET cutoff imposed by the geomagnetic field on GCR particle penetration into LEO. The high LET particles detected were mostly short-range (range < 2000 m), indicating that they were secondaries produced locally within the PNTD. The presence of these high LET particle fluences is important for the determination of dose equivalent because of the high Quality Factors (Q) involved. A relatively small fraction of particle fluence can contribute a large fraction of dose equivalent. Short-range, inelastic secondary particles produced by trapped protons in the South Atlantic Anomaly (SAA) were found to be a major contributor to the LET spectra above 100 keV/micrometer. The LET spectra were found to extend beyond the approximately 137 keV/micrometer relativistic GCR Fe peak to over 1000 keV/micrometer. The high LET tail of the LET spectra was measured in CR-39 and polycarbonate PNTDs using different techniques. GCR made a relatively modest contribution to the LET spectra as compared to the contributions from short-range secondary particles and stopping protons. LET spectra intercomparisons were made between LDEF measurements and exposures to 154 MeV accelerated proton beams. The similarities support the role of nuclear interactions by trapped protons as the major source of secondary particles in the PNTDs. Also techniques were employed to reduce the range cutoff for detection of the short-range secondaries to approximately 1 micrometer, so that essentially all secondary particles were included in the LET spectra. This has allowed a more realistic assessment of

  12. Theoretical spectra and atmospheres of extrasolar giant planets

    NASA Astrophysics Data System (ADS)

    Sudarsky, David L.

    This work is a detailed study of extrasolar giant planet (EGP) atmospheres and spectra. Models representative of the full range of systems known today are included, from the extreme close-in EGPs to Jovian-like planets at large orbital radii. Using a self-consistent planar atmosphere code along with the latest atomic and molecular cross sections, cloud models, Mie theory treatment of grain scattering and absorption, and incident stellar fluxes, I produce an extensive set of theoretical EGP atmosphere models and emergent spectra. The emergent spectra of EGPs strongly depend upon their outer atmospheric chemical compositions, which in turn depend upon the run of temperature and pressure with atmospheric depth. Because of qualitative similarities in the compositions and spectra of objects within several broad temperature ranges, EGPs fall naturally into five groups, or composition classes. Such a classification scheme, however preliminary, brings a degree of order to the rich variety of EGP systems known to exist today. Generic models that represent the EGP classes, as well as a set of specific models for a number of important systems that have been detected, are provided. Furthermore, the effects on emergent EGP spectra of varying key parameters such as surface gravity, cloud particle sizes, orbital distance, etc. are modeled. A discussion of current and future ground-based and space- based missions to detect and characterize EGPs in light of theoretical spectral models is included to facilitate an understanding of which systems are most likely to be studied successfully.

  13. Comparative Modelling of the Spectra of Cool Giants

    NASA Technical Reports Server (NTRS)

    Lebzelter, T.; Heiter, U.; Abia, C.; Eriksson, K.; Ireland, M.; Neilson, H.; Nowotny, W; Maldonado, J; Merle, T.; Peterson, R.; Plez, B.; Short, C. I.; Wahlgren, G. M.; Worley, C.; Aringer, B.; Bladh, S.; de Laverny, P.; Goswami, A.; Mora, A.; Norris, R. P.; Recio-Blanco, A.; Scholz, M.; Thevenin, F.; Tsuji, T.; Kordopatis, G.

    2012-01-01

    Our ability to extract information from the spectra of stars depends on reliable models of stellar atmospheres and appropriate techniques for spectral synthesis. Various model codes and strategies for the analysis of stellar spectra are available today. Aims. We aim to compare the results of deriving stellar parameters using different atmosphere models and different analysis strategies. The focus is set on high-resolution spectroscopy of cool giant stars. Methods. Spectra representing four cool giant stars were made available to various groups and individuals working in the area of spectral synthesis, asking them to derive stellar parameters from the data provided. The results were discussed at a workshop in Vienna in 2010. Most of the major codes currently used in the astronomical community for analyses of stellar spectra were included in this experiment. Results. We present the results from the different groups, as well as an additional experiment comparing the synthetic spectra produced by various codes for a given set of stellar parameters. Similarities and differences of the results are discussed. Conclusions. Several valid approaches to analyze a given spectrum of a star result in quite a wide range of solutions. The main causes for the differences in parameters derived by different groups seem to lie in the physical input data and in the details of the analysis method. This clearly shows how far from a definitive abundance analysis we still are.

  14. [An automated measurement of the galaxies spectra of LAMOST].

    PubMed

    Zhu, Guang-hua; Luo, A-Li; Zhao, Yong-heng

    2005-06-01

    To measure redshifts of the marge amount of galaxies' spectra automatically is the main goal of the data processing for the LAMOST project (Large Sky Area Multi-Object Optical Fiber Spectroscopic Telescope). A method called PCAZ can be applied to measure the very small redshifts (generally z < 0.2) due to the restriction of the wavelength range of the templates that are composed to make orthogonal templates. In the present article, the authors break the restriction by improving PCAZ method according to the characteristic of LAMOST spectra. Applying this new method to the SDSS data, more than 90% of the results are correct. The maximum limitation for redshift measurement of this new method depends on the wavelength range of the templates and the S/N of the blue parts of the spectra. According to the spectral feature of LAMOST, the authors can measure the galaxies with z < 0.8 correctly. From the experiment the authors concluded: first, this method can be used to measure the redshift of LAMOST spectra; second, the authors need to compose self-contained templates of various galaxies (UV-IR) to measure the survey redshift; finally, the S/N of the blue end of the spectra influences the measurement of the large redshift.

  15. Similarity spectra analysis of high-performance jet aircraft noise.

    PubMed

    Neilsen, Tracianne B; Gee, Kent L; Wall, Alan T; James, Michael M

    2013-04-01

    Noise measured in the vicinity of an F-22A Raptor has been compared to similarity spectra found previously to represent mixing noise from large-scale and fine-scale turbulent structures in laboratory-scale jet plumes. Comparisons have been made for three engine conditions using ground-based sideline microphones, which covered a large angular aperture. Even though the nozzle geometry is complex and the jet is nonideally expanded, the similarity spectra do agree with large portions of the measured spectra. Toward the sideline, the fine-scale similarity spectrum is used, while the large-scale similarity spectrum provides a good fit to the area of maximum radiation. Combinations of the two similarity spectra are shown to match the data in between those regions. Surprisingly, a combination of the two is also shown to match the data at the farthest aft angle. However, at high frequencies the degree of congruity between the similarity and the measured spectra changes with engine condition and angle. At the higher engine conditions, there is a systematically shallower measured high-frequency slope, with the largest discrepancy occurring in the regions of maximum radiation.

  16. Analytic calculations of anharmonic infrared and Raman vibrational spectra

    PubMed Central

    Louant, Orian; Ruud, Kenneth

    2016-01-01

    Using a recently developed recursive scheme for the calculation of high-order geometric derivatives of frequency-dependent molecular properties [Ringholm et al., J. Comp. Chem., 2014, 35, 622], we present the first analytic calculations of anharmonic infrared (IR) and Raman spectra including anharmonicity both in the vibrational frequencies and in the IR and Raman intensities. In the case of anharmonic corrections to the Raman intensities, this involves the calculation of fifth-order energy derivatives—that is, the third-order geometric derivatives of the frequency-dependent polarizability. The approach is applicable to both Hartree–Fock and Kohn–Sham density functional theory. Using generalized vibrational perturbation theory to second order, we have calculated the anharmonic infrared and Raman spectra of the non- and partially deuterated isotopomers of nitromethane, where the inclusion of anharmonic effects introduces combination and overtone bands that are observed in the experimental spectra. For the major features of the spectra, the inclusion of anharmonicities in the calculation of the vibrational frequencies is more important than anharmonic effects in the calculated infrared and Raman intensities. Using methanimine as a trial system, we demonstrate that the analytic approach avoids errors in the calculated spectra that may arise if numerical differentiation schemes are used. PMID:26784673

  17. Similarity spectra analysis of high-performance jet aircraft noise.

    PubMed

    Neilsen, Tracianne B; Gee, Kent L; Wall, Alan T; James, Michael M

    2013-04-01

    Noise measured in the vicinity of an F-22A Raptor has been compared to similarity spectra found previously to represent mixing noise from large-scale and fine-scale turbulent structures in laboratory-scale jet plumes. Comparisons have been made for three engine conditions using ground-based sideline microphones, which covered a large angular aperture. Even though the nozzle geometry is complex and the jet is nonideally expanded, the similarity spectra do agree with large portions of the measured spectra. Toward the sideline, the fine-scale similarity spectrum is used, while the large-scale similarity spectrum provides a good fit to the area of maximum radiation. Combinations of the two similarity spectra are shown to match the data in between those regions. Surprisingly, a combination of the two is also shown to match the data at the farthest aft angle. However, at high frequencies the degree of congruity between the similarity and the measured spectra changes with engine condition and angle. At the higher engine conditions, there is a systematically shallower measured high-frequency slope, with the largest discrepancy occurring in the regions of maximum radiation. PMID:23556581

  18. Anharmonic IR Spectra of Biomolecules: Nucleobases and Their Oligomers

    NASA Astrophysics Data System (ADS)

    Barone, Vincenzo; Biczysko, Malgorzata; Bloino, Julien; Carnimeo, Ivan; Fornaro, Teresa

    2014-06-01

    Computational spectroscopy techniques have become in the last years effective means to predict and characterize spectra, such as infrared, for molecular systems of increasing dimensions with account for different environments. We are actively developing a comprehensive and robust computational protocol, set within a perturbative vibrational framework [1], aimed at a quantitative reproduction of the spectra of biomolecules. In order to model the vibrational spectra of weakly bound molecular complexes, dispersion interactions should be taken into proper account. In this work, we present critical assessment of dispersion-corrected DFT approaches for anharmonic vibrational frequency calculations. It is shown that fully anharmonic IR spectra, simulated through full and reduced-dimensionality generalized second-order vibrational perturbation theory (GVPT2)[1] with the potential energy surfaces computed with the B3LYP-D3 approach, may be used to interpret experimental data of nucleobases and their complexes[2] by the direct comparison of experimental IR spectra with their theoretical anharmonic counterpart, taking into account also overtones and combination bands. [1] V. Barone, M. Biczysko, J. Bloino, Phys. Chem. Chem. Phys., 2014,16, 1759-1787 [2] T. Fornaro, M. Biczysko, S. Monti, V. Barone, Phys. Chem. Chem. Phys., 2014, DOI: 10.1039/C3CP54724H

  19. Faster SEQUEST Searching for Peptide Identification from Tandem Mass Spectra

    PubMed Central

    Diament, Benjamin; Noble, William Stafford

    2011-01-01

    Computational analysis of mass spectra remains the bottleneck in many proteomics experiments. SEQUEST was one of the earliest software packages to identify peptides from mass spectra by searching a database of known peptides. Though still popular, SEQUEST performs slowly. Crux and TurboSEQUEST have successfully sped up SEQUEST by adding a precomputed index to the search, but the demand for ever-faster peptide identification software continues to grow. Tide, introduced here, is a software program that implements the SEQUEST algorithm for peptide identification and that achieves a dramatic speedup over Crux and SEQUEST. The optimization strategies detailed here employ a combination of algorithmic and software engineering techniques to achieve speeds up to 170 times faster than a recent version of SEQUEST that uses indexing. For example, on a single Xeon CPU, Tide searches 10,000 spectra against a tryptic database of 27,499 C. elegans proteins at a rate of 1,550 spectra per second, which compares favorably with a rate of 8.8 spectra per second for a recent version of SEQUEST with index running on the same hardware. PMID:21761931

  20. The mid-infrared transmission spectra of Antarctic ureilites

    NASA Technical Reports Server (NTRS)

    Sandford, Scott A.

    1993-01-01

    The mid-IR (4000-450/cm; 2.5-22.2 microns) transmission spectra of seven Antarctic ureilites and 10 Antarctic H-5 ordinary chondrites are presented. The ureilite spectra show a number of absorption bands, the strongest of which is a wide, complex feature centered near 1000/cm (10 microns) due to Si-O stretching vibrations in silicates. The profiles and positions of the substructure in this feature indicate that Mg-rich olivines and pyroxenes are the main silicates responsible. The relative abundances of these two minerals, as inferred from the spectra, show substantial variation from meteorite to meteorite, but generally indicate olivine is the most abundant (olivine:pyroxene = 60:40 to 95:5). Both the predominance of olivine and the variable olivine-to-pyroxene ratio are consistent with the known composition and heterogeneity of ureilites. The H-5 ordinary chondrites spanned a range of weathering classes and were used to provide a means of addressing the extent to which the ureilite spectra may have been altered by weathering processes. It was found that, while weathering of these meteorites produces some weak bands due to the formation of small amounts of carbonates and hydrates, the profile of the main silicate feature has been little affected by Antarctic exposure in the meteorites studied here. The mid-IR ureilite spectra provide an additional means of testing potential asteroidal parent bodies for the ureilites.