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Sample records for broadening line

  1. Stark broadening of B IV spectral lines

    Science.gov (United States)

    Dimitrijević, Milan S.; Christova, Magdalena; Simić, Zoran; Kovačević, Andjelka; Sahal-Bréchot, Sylvie

    2016-08-01

    Stark broadening parameters for 157 multiplets of helium-like boron (B IV) have been calculated using the impact semiclassical perturbation formalism. Obtained results have been used to investigate the regularities within spectral series. An example of the influence of Stark broadening on B IV lines in DO white dwarfs is given.

  2. Stark broadening of B IV spectral lines

    CERN Document Server

    Dimitrijevic, Milan S; Simic, Zoran; Kovacevic, Andjelka; Sahal-Brechot, Sylvie

    2016-01-01

    Stark broadening parameters for 157 multiplets of helium like boron (B IV) have been calculated using the impact semiclassical perturbation formalism. Obtained results have been used to investigate the regularities within spectral series. An example of the influence of Stark broadening on B IV lines in DO white dwarfs is given.

  3. Line Broadening and the Solar Opacity Problem

    Science.gov (United States)

    Krief, M.; Feigel, A.; Gazit, D.

    2016-06-01

    The calculation of line widths constitutes theoretical and computational challenges in the calculation of opacities of hot, dense plasmas. Opacity models use line broadening approximations that are untested at stellar interior conditions. Moreover, calculations of atomic spectra of the Sun indicate a large discrepancy in the K-shell line widths between several atomic codes and the Opacity-Project (OP). In this work, the atomic code STAR is used to study the sensitivity of solar opacities to line broadening. Variations in the solar opacity profile due to an increase of the Stark widths resulting from discrepancies with OP, are compared, in light of the solar opacity problem, with the required opacity variations of the present day Sun, as imposed by helioseismic and neutrino observations. The resulting variation profile is much larger than the discrepancy between different atomic codes, agrees qualitatively with the missing opacity profile, recovers about half of the missing opacity nearby the convection boundary, and has a little effect in the internal regions. Since it is hard to estimate quantitatively the uncertainty in the Stark widths, we show that an increase of all line widths by a factor of about ˜100 recovers quantitatively the missing opacity. These results emphasize the possibility that photoexcitation processes are not modeled properly, and more specifically, highlight the need for a better theoretical characterization of the line broadening phenomena at stellar interior conditions, and of the uncertainty due to the way it is implemented by atomic codes.

  4. Line broadening and the solar opacity problem

    CERN Document Server

    Krief, M; Gazit, D

    2016-01-01

    The calculation of line widths constitutes a theoretical as well as a computational challenge in the calculation of opacities of hot dense plasmas. Opacity models use line broadening approximations that are untested at stellar interior conditions. Moreover, calculations of atomic spectra nearby the convection zone boundary (CZB) of the sun, indicate a large discrepancy in the K-shell line widths between several atomic codes and the Opacity-Project. In this work, the atomic code STAR is used to study the sensitivity of solar opacities to line-broadening. Atomic spectra of several elements are analyzed and compared within the solar interior. Variations in the solar opacity profile due to changes in the Stark widths are shown to be significant and to result mainly due to K-shell lines. In light of the solar opacity problem, the results are compared with the required opacity variations of the present day sun, as imposed by helioseismic and neutrino observations. It is shown that an increase of the line widths res...

  5. Stark Broadening in Compact Stars: Xe VI Lines

    Indian Academy of Sciences (India)

    Milan S. Dimitrijević; Zoran Simić; Andjelka Kovačević; Aleksandar Valjarević; Sylvie Sahal-Bréchot

    2015-12-01

    We will consider Stark broadening of non hydrogenic spectral lines in the impact approximation in compact stars: pre-white dwarf and white dwarf atmospheres. In order to show an example, Stark broadening parameters have been calculated, using the impact semiclassical perturbation approach for four Xe VI spectral lines. Obtained results have been used to demonstrate the influence of Stark broadening in DA and DB white dwarf atmospheres.

  6. Effect of line broadening on the performance of Faraday filters

    CERN Document Server

    Zentile, Mark A; Whiting, Daniel J; Keaveney, James; Adams, Charles S; Hughes, Ifan G

    2015-01-01

    We show that homogeneous line broadening drastically affects the performance of atomic Faraday filters. We use a computerized optimization algorithm to find the best magnetic field and temperature for Faraday filters with a range of cell lengths. The effect of self-broadening is found to be particularly important for short vapour cells, and for `wing-type' filters. Experimentally we realize a Faraday filter using a micro-fabricated $^{87}$Rb vapour cell. By modelling the filter spectrum using the ElecSus program we show that additional homogeneous line broadening due to the background buffer-gas pressure must also be included for an accurate fit.

  7. Stark Broadening Parameters for Neutral Oxygen Spectral Lines

    Indian Academy of Sciences (India)

    N. Alonizan; R. Qindeel; N. Ben Nessib; S. Sahal-Bréchot; Milan S. Dimitrijević

    2015-12-01

    Stark broadening parameters for nine neutral oxygen (O I) lines have been determined within the impact approximation and the semiclassical perturbation method. The atomic data have been taken from the TOPbase and NIST atomic databases. The electron and proton Stark widths and shifts and ion broadening parameter values for these O I lines have been calculated for electron density of 1016 cm$^{−3}$ and for 4 different electron temperatures in the range of 5000 K to 40000 K. These Stark broadening parameters are compared with our previous results (Ben Nessib, N. et al. 1996, Physica Scripta, 54, 603–613), where we calculated Stark broadening parameters for only four O I spectral lines and where Stark widths and shifts were compared with experimental and theoretical data available in the literature. In the present paper, we have also compared our results with the Griem's book (Griem, H. R. 1974, Spectral line broadening by plasmas) and VALD (Ryabchikova, T. et al. 2015, Physica Scripta, 90, 054005) values.

  8. Robust Algorithm for Computing Statistical Stark Broadening of Spectral Lines

    Energy Technology Data Exchange (ETDEWEB)

    Iglesias, C A; Sonnad, V

    2010-02-10

    A method previously developed to solve large-scale linear systems is applied to statistical Stark broadened line shape calculations. The method is formally exact, numerically stable, and allows optimization of the integration over the quasi-static field to assure numerical accuracy. Furthermore, the method does not increase the computational effort and often can decrease it compared to the conventional approach.

  9. Curves of growth for van der Waals broadened spectral lines

    Science.gov (United States)

    Park, C.

    1980-01-01

    Curves of growth are evaluated for a spectral line broadened by the van der Waals interactions during collisions. The growth of the equivalent widths of such lines is shown to be dependent on the product of the perturber density and the 6/10 power of the van der Waals potential coefficient. When the parameter is small, the widths grow as the 1/2 power of the optical depth as they do for the Voigt profile: but when the parameter is large, they grow as 2/3 power and, hence, faster than the Voigt profile. An approximate analytical expression for the computed growth characteristics is given.

  10. On the Stark Broadening of Lu III Spectral Lines

    Indian Academy of Sciences (India)

    Zlatko Majlinger; Zoran Simić; Milan S. Dimitrijević

    2015-12-01

    The electron-impact widths for 27 Lu III spectral lines have been calculated by using the modified semiempirical method. Calculations have been also performed with the published relativistic Hartree-Fock oscillator strengths and additionally, with the approximate formula of Cowley.With the obtained results, the influence of Stark broadening on Lu III lines was investigated in the spectra of A-type stars. The obtained data will be included in the STARK-B database, which is part of the Virtual Atomic and Molecular Data Center – VAMDC.

  11. Non-thermal line-broadening in solar prominence

    CERN Document Server

    Stellmacher, Goetz

    2016-01-01

    We show that the line broadening in quiescent solar prominences is mainly due to non-thermal velocities. We have simultaneously observed a wide range of optically thin lines in quiescent prominences, selected for bright and narrow Mg\\,b emission without line satellites from macro-shifts. We find a ratio of reduced widths of H-gamma and H-delta of 1.05 +-0.03 which can hardly be attributed to saturation, since both are optically thin for the prominences observed: tau(gamma)<0.3 ; tau(delta)<0.15. We confirm the ratio of reduced widths of He4772(triplet) and He5015(singlet of 1.1 +-0.05 at higher significance and detect a width ratio of Mgb2 and Mg4571 (both from the triplet system) of 1.3 +-0.1. The discrepant widths of lines from different atoms, and even from the same atom, cannot be represented by a unique pair [T_kin ; V_nth]. Values of T_kin deduced from observed line radiance using models, indicate low temperatures down to T_kin~5000K. Non-thermal velocities, related to different physical states of...

  12. Comparing the line broadened quasilinear model to Vlasov code

    Energy Technology Data Exchange (ETDEWEB)

    Ghantous, K. [Laboratoire de Physique des Plasmas, Ecole Polytechnique, 91128 Palaiseau Cedex (France); Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543-0451 (United States); Berk, H. L. [Institute for Fusion Studies, University of Texas, 2100 San Jacinto Blvd, Austin, Texas 78712-1047 (United States); Gorelenkov, N. N. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543-0451 (United States)

    2014-03-15

    The Line Broadened Quasilinear (LBQ) model is revisited to study its predicted saturation level as compared with predictions of a Vlasov solver BOT [Lilley et al., Phys. Rev. Lett. 102, 195003 (2009) and M. Lilley, BOT Manual. The parametric dependencies of the model are modified to achieve more accuracy compared to the results of the Vlasov solver both in regards to a mode amplitude's time evolution to a saturated state and its final steady state amplitude in the parameter space of the model's applicability. However, the regions of stability as predicted by LBQ model and BOT are found to significantly differ from each other. The solutions of the BOT simulations are found to have a larger region of instability than the LBQ simulations.

  13. Comparing the line broadened quasilinear model to Vlasov code

    Science.gov (United States)

    Ghantous, K.; Berk, H. L.; Gorelenkov, N. N.

    2014-03-01

    The Line Broadened Quasilinear (LBQ) model is revisited to study its predicted saturation level as compared with predictions of a Vlasov solver BOT [Lilley et al., Phys. Rev. Lett. 102, 195003 (2009) and M. Lilley, BOT Manual. The parametric dependencies of the model are modified to achieve more accuracy compared to the results of the Vlasov solver both in regards to a mode amplitude's time evolution to a saturated state and its final steady state amplitude in the parameter space of the model's applicability. However, the regions of stability as predicted by LBQ model and BOT are found to significantly differ from each other. The solutions of the BOT simulations are found to have a larger region of instability than the LBQ simulations.

  14. Gain and Raman line-broadening with graphene coated diamond-shape nano-antennas.

    Science.gov (United States)

    Paraskevaidis, Charilaos; Kuykendall, Tevye; Melli, Mauro; Weber-Bargioni, Alexander; Schuck, P James; Schwartzberg, Adam; Dhuey, Scott; Cabrini, Stefano; Grebel, Haim

    2015-10-01

    Using Surface Enhanced Raman Scattering (SERS), we report on intensity-dependent broadening in graphene-deposited broad-band antennas. The antenna gain curve includes both the incident frequency and some of the scattered mode frequencies. By comparing antennas with various gaps and types (bow-tie vs. diamond-shape antennas) we make the case that the line broadening did not originate from strain, thermal or surface potential. Strain, if present, further shifts and broadens those Raman lines that are included within the antenna gain curve.

  15. Gain and Raman line-broadening with graphene coated diamond-shape nano-antennas.

    Science.gov (United States)

    Paraskevaidis, Charilaos; Kuykendall, Tevye; Melli, Mauro; Weber-Bargioni, Alexander; Schuck, P James; Schwartzberg, Adam; Dhuey, Scott; Cabrini, Stefano; Grebel, Haim

    2015-10-01

    Using Surface Enhanced Raman Scattering (SERS), we report on intensity-dependent broadening in graphene-deposited broad-band antennas. The antenna gain curve includes both the incident frequency and some of the scattered mode frequencies. By comparing antennas with various gaps and types (bow-tie vs. diamond-shape antennas) we make the case that the line broadening did not originate from strain, thermal or surface potential. Strain, if present, further shifts and broadens those Raman lines that are included within the antenna gain curve. PMID:26332298

  16. On the influence of Stark broadening on Si I lines in stellar atmospheres

    CERN Document Server

    Dimitrijevic, M S; Popovic, L C; Shulyak, D; Tsymbal, V V

    2003-01-01

    We study the influence of Stark broadening and stratification effects on Si\\i lines in the rapidly oscillating (roAp) star 10 Aql, where the Si\\i 6142.48 \\AA and 6155.13 \\AA lines are asymmetrical and shifted. First we have calculated Stark broadening parameters using the semiclassical perturbation method for three Si\\i lines: 5950.2 \\AA, 6142.48 \\AA and 6155.13 \\AA. We revised the synthetic sp$ calculation code taking into account both Stark width and shift for these lines. From the comparison of our calculations with the observations we found that Stark broadening + the stratification effect can explain asymmetry of the Si\\i 6142.48 \\AA and 6155.13 \\AA lines in the atmospere of roAp star 10 Aql.

  17. Pressure shift and broadening of the 254-nm intercombination line of mercury by N2

    International Nuclear Information System (INIS)

    We have used laser absorption spectroscopy to study the collisional broadening and shift of the 254-nm 6 1S0→6 3P1 intercombination line of Hg in the presence of N2 for pressures below 400 Torr. This study comprises the first measurements of the proportionality constants for pressure broadening and shift of Hg due to N2 in this pressure range, and the first high-precision measurements of these pressure effects on Hg for any foreign gas. We obtain -2.54(2) MHz/Torr for the shift and 9.01(4) MHz/Torr for the broadening (full width at half maximum) at 21 degree sign C (95% confidence interval). These results are important for ongoing experiments using optical pumping of mercury in tests of fundamental symmetries, as well as for characterization of interatomic forces and tests of the theory of collisional line broadening

  18. An experimental investigation into power broadening of the Na-D lines in a flame

    International Nuclear Information System (INIS)

    Investigations are described aimed at the verification of the existence of power broadening in fluorescence, as predicted by theory in the case of a broadband excitation source. Measurements were performed on a vapour of sodium (Na) atoms in a pre-mixed H2-O2-Ar flame under 1 atm pressure. The easily excited first resonance (or D) lines of Na were chosen for the observation of power broadening in fluorescence. (Auth.)

  19. Pressure dependence of Na resonance line broadening by Kr and Xe

    Energy Technology Data Exchange (ETDEWEB)

    West, W.P.; Gallagher, A.

    1978-04-01

    The fluorescent spectrum of the Na D lines, pressure broadened by Xe and Kr, has been measured for noble-gas densities of 2 x 10/sup 1/9--3 x 10/sup 2/0 cm/sup -/3; at the lower density, the lines are isolated while, at the higher, they are severely blended. The spectra are obtained in normalized intensity units allowing the nonbinary behavior of the line wing intensity to be clearly observed. At the lower density the broadening is well characterized by isolated binary interactions; at the higher density multiple-perturber interactions dominate. Nonlinearities in the pressure dependence of shifts, widths, and satellite shape are reported.

  20. Temperature-Dependent Line Shift and Broadening of CO Infrared Transitions.

    Science.gov (United States)

    Drascher; Giesen; Wang; Schmücker; Schieder; Winnewisser; Joubert; Bonamy

    1998-12-01

    The temperature dependence of lineshift and broadening of the rovibrational transitions R(18) and R(20) of the CO fundamental band, perturbed by Ar, N2, O2, and H2, have been measured with high frequency accuracy and at temperatures between 160 and 270 K in steps of 20 K. A wavelength stabilized tunable diode laser spectrometer has been combined with a low temperature long path cell of 134 m absorption length and 1 m basis length. For all measurements the CO pressure was below 0.1 mbar to avoid self-shift and self-broadening. In case of line broadening the temperature dependence is quite well reproduced by an exponential relation, b(T) = b(T0)(T/T0)-n. For all foreign gases, the exponent n has been obtained (0.53 line broadening and shift for CO with Ar and the broadening of CO by N2 and O2 have been compared to calculations from the semi-classical theory of Robert and Bonamy. Sufficient agreement has been achieved for the line broadening, while the calculated shifts are for all temperatures larger than the measured values. Copyright 1998 Academic Press.

  1. Study of ion line broadening in the Tormac discharge

    International Nuclear Information System (INIS)

    Tormac (Toroidal Magnetic Cusp) is a magnetic confinement plasma concept having absolute minimum-B geometry. Two versions of Tormac are considered here. Tormac T IV-c has a glass vessel of rectangular cross section, 0.5 m in diameter. The confinement field rises to approx. 4.5 kG in approx. 8.3 μsec. Tormac T V has a T-shaped glass vessel, 1 m in diameter, with a field of approx. 3 kG, rising in approx. 10 μsec. Gaussian HeII 4686 A spectral lines having full widths at half maximum over 2 A have been observed in both Tormac plasmas

  2. Variable rotational line broadening in the Be star Achernar

    CERN Document Server

    Rivinius, Th; Townsend, R H D; Carciofi, A C; Štefl, S

    2013-01-01

    The main theoretical problem for the formation of a Keplerian disk around Be stars is how to supply angular momentum from the star to the disk, even more so since Be stars probably rotate somewhat sub-critically. For instance, nonradial pulsation may transport angular momentum to the stellar surface until (part of) this excess supports the disk formation/replenishment. The nearby Be star Achernar is presently building a new disk and offers an excellent opportunity to observe this process from relatively close-up. Spectra from various sources and epochs are scrutinized to identify the salient stellar parameters characterizing the disk life cycle as defined by H\\alpha emission. Variable strength of the non-radial pulsation is confirmed, but does not affect the further results. For the first time it is demonstrated that the photospheric line width does vary in a Be star, by as much as \\Delta v sin i \\lesssim 35kms^{-1}. However, contrary to assumptions in which a photospheric spin-up accumulates during the diskl...

  3. Line broadening interference for high-resolution nuclear magnetic resonance spectra under inhomogeneous magnetic fields.

    Science.gov (United States)

    Wei, Zhiliang; Yang, Jian; Chen, Youhe; Lin, Yanqin; Chen, Zhong

    2015-04-01

    Nuclear magnetic resonance spectroscopy serves as an important tool for analyzing chemicals and biological metabolites. However, its performance is subject to the magnetic-field homogeneity. Under inhomogeneous fields, peaks are broadened to overlap each other, introducing difficulties for assignments. Here, we propose a method termed as line broadening interference (LBI) to provide high-resolution information under inhomogeneous magnetic fields by employing certain gradients in the indirect dimension to interfere the magnetic-field inhomogeneity. The conventional spectral-line broadening is thus interfered to be non-diagonal, avoiding the overlapping among adjacent resonances. Furthermore, an inhomogeneity correction algorithm is developed based on pattern recognition to recover the high-resolution information from LBI spectra. Theoretical deductions are performed to offer systematic and detailed analyses on the proposed method. Moreover, experiments are conducted to prove the feasibility of the proposed method for yielding high-resolution spectra in inhomogeneous magnetic fields.

  4. Line broadening in the PXRD patterns of layered hydroxides: The relative effects of crystallite size and structural disorder

    Indian Academy of Sciences (India)

    Grace S Thomas; P Vishnu Kamath

    2006-01-01

    Layered hydroxides crystallize in a hexagonal structure and incorporate a number of different types of structural disorders as an exigency of anisotropic bonding. Structural disorder contributes to the non-uniform broadening of lines in the powder X-ray diffraction pattern. Common among the disorders are stacking faults, which broaden the ℎ0ℓ/0ℓ reflections. Interstratification selectively broadens the 00ℓ reflections and turbostratic disorder broadens the 0ℓ reflections. The line broadening caused by structural disorder has to be discounted before estimates of particle size are made by applying the Scherrer formula.

  5. Line Mixing and Broadening in the Raman Q Branch of HD at 304.6 K.

    Science.gov (United States)

    Sheldon; Sinclair; Le Flohic MP; Drummond; May

    1998-12-01

    The Q-branch lines of pure HD were measured at densities ranging from 1 to 7 Amagat at 304.6 K. Each profile was fitted to the well-known Rosenkranz expression to extract the size of the asymmetry due to line mixing as well as to the linewidth. Line mixing and broadening coefficients were obtained by fitting the asymmetries and widths to a straight line as a function of gas density. Apart from a single existing measurement for the Q(0) line, our mixing coefficients are the first direct measurements of the asymmetry due to line mixing in HD. Our broadening coefficients are consistent with the best earlier measurements but are an order of magnitude more precise. Agreement is found with some existing semiclassical calculations of broadening. We have fitted our HD broadening coefficients to a variety of empirical energy gap laws. Our conclusions are that none of the exponential gap law (EGL), the modified exponential gap (MEG) law, and the statistical power gap (SPG) law successfully models our broadening coefficients. We present a modified version of the EGL and the MEG laws, which are successful in reproducing the experimental results. Using the fitted parameters of the new gap law, we have calculated the relaxation matrix of HD at room temperature. With this relaxation matrix, we have simulated the Q-branch spectrum at a number of densities between 49.1 and 490 Amagat and compared the results with previous high-density measurements. At all densities and frequencies, the simulated spectral intensity was found to agree with the measured strength within about 5% of the peak of the spectrum. In addition, the comparison provides evidence of a nonlinear vibrational dephasing shift in HD. Copyright 1998 Academic Press.

  6. Calculation of the density shift and broadening of the transition lines in pionic helium: Computational problems

    Energy Technology Data Exchange (ETDEWEB)

    Bakalov, Dimitar, E-mail: dbakalov@inrne.bas.bg [Bulgarian Academy of Sciences, INRNE (Bulgaria)

    2015-08-15

    The potential energy surface and the computational codes, developed for the evaluation of the density shift and broadening of the spectral lines of laser-induced transitions from metastable states of antiprotonic helium, fail to produce convergent results in the case of pionic helium. We briefly analyze the encountered computational problems and outline possible solutions of the problems.

  7. On quantum-mechanical unified theories of collisional spectral line broadening

    NARCIS (Netherlands)

    Schuller, F.; Nienhuis, G.

    1982-01-01

    We compare the Baranger-type unified theory of line broadening with a quantum version of the binary-collision approach. For the simple model system of a two-state atom, where both treatments are well-defined, the binary-collision theory results only from the exact formalism after an inversion of an

  8. LBQ2D, Extending the Line Broadened Quasilinear Model to TAE-EP Interaction

    Science.gov (United States)

    Ghantous, Katy; Gorelenkov, Nikolai; Berk, Herbert

    2012-10-01

    The line broadened quasilinear model was proposed and tested on the one dimensional electrostatic case of the bump on tailfootnotetextH.L Berk, B. Breizman and J. Fitzpatrick, Nucl. Fusion, 35:1661, 1995 to study the wave particle interaction. In conventional quasilinear theory, the sea of overlapping modes evolve with time as the particle distribution function self consistently undergo diffusion in phase space. The line broadened quasilinear model is an extension to the conventional theory in a way that allows treatment of isolated modes as well as overlapping modes by broadening the resonant line in phase space. This makes it possible to treat the evolution of modes self consistently from onset to saturation in either case. We describe here the model denoted by LBQ2D which is an extension of the proposed one dimensional line broadened quasilinear model to the case of TAEs interacting with energetic particles in two dimensional phase space, energy as well as canonical angular momentum. We study the saturation of isolated modes in various regimes and present the analytical derivation and numerical results. Finally, we present, using ITER parameters, the case where multiple modes overlap and describe the techniques used for the numerical treatment.

  9. Study of stark broadening of high-Z hydrogenic ion lines in dense hot plasmas

    International Nuclear Information System (INIS)

    Stark broadened x-ray line profiles from highly ionized hydrogenic ions, radiating while immersed in a hot dense plasma, are studied. The broadening effects produced by the ions present in the plasma are treated through the use of static electric microfield distribution functions. The microfield distribution functions employed have the following properties: (1) the radiating hydrogenic ion may have any net charge; (2) the perturbing ions and electrons in the plasma may have different kinetic temperatures; and (3) two species of ions, of charge z1 and z2, may be present in any given ratio

  10. Broadening of a spectrum line by finite spectrometer resolution. [FORTRAN IV; SAL, KAL

    Energy Technology Data Exchange (ETDEWEB)

    Engleman, R. Jr.

    1978-12-01

    The distortion of a spectrum line by the finite resolving power of a spectrometer is discussed in terms of a mathematical model. Particular attention is given to the case where either a Gaussian or Cauchy slit function broadens an isolated Doppler, Lorentz, or Voigt absorption line. Corrections to the peak absorption, the line width, and the integrated absorption coefficient are calculated and discussed for different combinations of slit functions and line shapes. Several new series expansions for the corrections are derived. Two general FORTRAN IV programs that calculate these corrections are described and some sample correction curves are given. 27 references.

  11. Plasma motions and non-thermal line broadening in flaring twisted coronal loops

    CERN Document Server

    Gordovskyy, Mykola; Browning, Philippa

    2015-01-01

    Observation of coronal EUV spectral lines offers an opportunity to evaluate the thermal structure and flows in flaring atmospheres. This, in turn, can be used to estimate the partitioning between the thermal and kinetic energies released in flares. Our aim is to forward-model large-scale (50-10000 km) velocity distributions in order to interpret non-thermal broadening of different spectral EUV lines observed in flares. The developed models allow us to understand the origin of the observed spectral line shifts and broadening, and link these features to particular physical phenomena in flaring atmospheres. We use ideal MHD to derive unstable twisted magnetic fluxtube configurations in a gravitationally-stratified atmosphere. The evolution of these twisted fluxtubes is followed using resistive MHD, with anomalous resistivity depending on the local density and temperature. The model also takes into account the thermal conduction and radiative losses. The model allows us to evaluate average velocities and velocity...

  12. Stark broadening measurement of the beta Paschen line of the hydrogen in a linear discharge

    International Nuclear Information System (INIS)

    The stark broadening of the beta Paschen line of the hydrogen is determined from the profile measurements of the emitted line in a helium plasma with 0,5% of hidrogen. The plasma is a pulsed linear discharge generated by a damped oscillatory current with peak intensity of 20 kA. Electronic densities are determined from the 4471A sup(o) line of the HeI. The profiles are measured by the display to display method, utilizing a 75 cm focal distance monochromator and an InSb detector. The results obtained are compared with semiclassical calculations. (L.C.)

  13. The variable temperature pressure broadening and line shift of CO and HDO in collision with helium

    International Nuclear Information System (INIS)

    Pressure broadening and line shift cross sections for the 1 left-arrow 0 and 2 left-arrow 1 rotational transitions of carbon monoxide (CO) in collision with Helium (He) have been measured between 1 and 600 K. Measurements below 30 K were made using the collisional cooling technique, while measurements at higher temperatures were made in an equilibrium cell. The experimental apparatus and techniques employed in the study are described. The data are compared with theoretical predictions, and the significant differences between predictions based on the best available potential energy surface and the experimental results are discussed. Recent studies of the pressure broadening and line shifting of the 110 left-arrow 111 rotational transition of deuterated water (HDO) in collision with He will also be presented

  14. Collisional shift and broadening of the transition lines in pionic helium

    Science.gov (United States)

    Obreshkov, Boyan; Bakalov, Dimitar

    2016-06-01

    We calculate the density shift and broadening of selected dipole transition lines of pionic helium in gaseous helium at low temperatures up to T =12 K and pressure up to a few bars. In the approximation of binary collisions the shift and broadening depend linearly on the density; we evaluate the slope of this linear dependence for a few spectral lines of known experimental interest and also investigate its temperature dependence. We find a blueshift of the resonance frequencies of the (n ,l )=(16 ,15 )→(16 ,14 ) , (17 ,16 )→(17 ,15 ) , and (16 ,15 )→(17 ,14 ) unfavored transitions and a redshift for the favored one, (17 ,16 )→(16 ,15 ) . The results are intended to significantly increase the efficiency of the laser spectroscopy investigations of pionic helium and help with the interpretation of the experimental data.

  15. Collisional shift and broadening of the transition lines in pionic helium

    CERN Document Server

    Obreshkov, Boyan

    2016-01-01

    We calculate the density shift and broadening of selected dipole transition lines of pionic helium in gaseous helium at low temperatures up to T=12 K and pressure up to a few bar. In the approximation of binary collisions the shift and broadening depend linearly on the density; we evaluate the slope of this linear dependence a few spectral lines of known experimental interest, and also investigate its temperature dependence. We find blue shift of the resonance frequencies of the $(n,l)=(16,15) \\rightarrow (16,14) $, $(17,16) \\rightarrow (17,15)$, and $(16,15)\\rightarrow(17,14)$ transitions, and red shift for the favored transition $(17,16) \\rightarrow (16,15)$. The results are intended to significantly increase the efficiency of the laser spectroscopy investigation of pionic helium and help the interpretation of the experimental data.

  16. Studying Turbulence from Doppler-broadened Absorption Lines: Statistics of Logarithms of Intensity

    CERN Document Server

    Lazarian, A

    2008-01-01

    We continue our work on developing techniques for studying turbulence with spectroscopic data. We show that Doppler-broadened absorption spectral lines, in particularly, saturated absorption lines, can be used within the framework of the earlier-introduced technique termed the Velocity Coordinate spectrum (VCS). The VCS relates the statistics of fluctuations along the velocity coordinate to the statistics of turbulence, thus it does not require spatial coverage by sampling directions in the plane of the sky. We consider lines with different degree of absorption and show that for lines of optical depth less than one, our earlier treatment of the VCS developed for spectral emission lines is applicable, if the optical depth is used instead of intensity. This amounts to correlating the logarithms of absorbed intensities. For larger optical depths and saturated absorption lines, we show, that the amount of information that one can use is, inevitably, limited by noise. In practical terms, this means that only wings...

  17. Resin Dynamics Contributes to the NMR Line Broadening of Organic Molecules Grafted onto a Polystyrene Resin

    Science.gov (United States)

    Lippens, Guy; Chessari, Gianni; Wieruszeski, Jean-Michel

    2002-06-01

    Despite the use of high resolution magic angle spinning NMR, the NMR linewidth of anchored molecules on the commonly used Merrifield solid phase resins remains larger than that of the corresponding molecules in solution. We investigate the different mechanisms that might be at the origin of this line broadening. Experimentally, we use the CPMG method to determine the 15N relaxation times of a tethered tripeptide and show that the slow resin dynamics significantly contributes to the transverse relaxation.

  18. Power-law temperature dependence of collision broadening and shift of atomic and molecular rovibronic lines

    International Nuclear Information System (INIS)

    The classical phase-shift theory of spectral line shapes is used to examine various aspects of the applicability of the power-law relations to the description of temperature variations of pressure broadening and shifting coefficients of the isolated atomic and rovibronic molecular lines in a wide temperature range. Model calculations performed for potentials of the Lennard-Jones type indicate that the temperature dependence exponents of the broadening and shifting can be related to the details of the intermolecular interactions. It is shown that they are sensitive to the range of temperatures assumed in the fit and therefore extreme care must be taken when the power-law temperature dependence is used as a scaling law. The problems of the failure of the power-law and of variations in the sign of pressure shift coefficients with increasing temperature are discussed. Very good fits of Frost's empirical formula for temperature dependence of pressure shift to the theoretical ones are obtained. -- Highlights: ► Classical theory of line shapes is used to examine the power-law relations. ► The broadening and shifting exponents depend on the range of temperatures in the fit. ► Extreme care must be taken when using the power-law dependence as a scaling law

  19. Electron Stark Broadening Database for Atomic N, O, and C Lines

    Science.gov (United States)

    Liu, Yen; Yao, Winifred M.; Wray, Alan A.; Carbon, Duane F.

    2012-01-01

    A database for efficiently computing the electron Stark broadening line widths for atomic N, O, and C lines is constructed. The line width is expressed in terms of the electron number density and electronatom scattering cross sections based on the Baranger impact theory. The state-to-state cross sections are computed using the semiclassical approximation, in which the atom is treated quantum mechanically whereas the motion of the free electron follows a classical trajectory. These state-to-state cross sections are calculated based on newly compiled line lists. Each atomic line list consists of a careful merger of NIST, Vanderbilt, and TOPbase line datasets from wavelength 50 nm to 50 micrometers covering the VUV to IR spectral regions. There are over 10,000 lines in each atomic line list. The widths for each line are computed at 13 electron temperatures between 1,000 K 50,000 K. A linear least squares method using a four-term fractional power series is then employed to obtain an analytical fit for each line-width variation as a function of the electron temperature. The maximum L2 error of the analytic fits for all lines in our line lists is about 5%.

  20. Stark Broadening of several Ar I Spectral Lines in the Visible Part of the Spectrum

    CERN Document Server

    Dimitrijevic, Milan S; Simic, Zoran; Sahal-Brechot, Sylvie

    2012-01-01

    In order to complete data on Stark broadening parameters for Ar I line in the visible spectrum, we determined Stark widths and shifts due to electron, proton, and ionized helium impacts, for nine lines (4191.0, 4259.4, 5912.1, 6043.2, 6045.0, 6752.9, 7503.9, 7514.6, 7724.2 {\\AA}), using jK coupling and semiclassical-perturbation theory. The obtained results will enter the STARK-B database, which is a part of Virtual Atomic and Molecular Data Center.

  1. Stark Broadening of in III Lines in Astrophysical and Laboratory Plasma

    CERN Document Server

    Simic, Z; Kovacevic, A B; Sahal-Brechot, S

    2012-01-01

    Besides the need of Stark broadening parameters for a number of problems in physics, and plasma technology, in hot star atmospheres the conditions exist where Stark widths are comparable and even larger than the thermal Doppler widths. Using the semiclassical perturbation method we investigated here the influence of collisions with charged particles for In III spectral lines. We determined a number of Stark broadening parameters important for the investigation of plasmas in the atmospheres of A-type stars and white dwarfs. Also, we have compared the obtained results with existing experimental data. The results will be included in the STARK-B database, the Virtual Atomic and Molecular Data Center and the Serbian Virtual Observatory.

  2. Stark broadening of high-principal-quantum-number n-alpha lines of hydrogen.

    Science.gov (United States)

    Lasalle, T. R.; Nee, T.-J.; Griem, H. R.

    1973-01-01

    High n-alpha lines (transitions n + 1 to n) with quantum numbers n between 50 and 250 have been observed emanating from galactic H II regions where the electron density and temperature are about 1000/cu cm and 1 eV, respectively. High n-alpha lines have not previously been seen in the laboratory where fairly homogeneous plasmas may be produced and relatively precise measurements of electron densities and temperatures can be made. The present work describes experiments where the first members of the hydrogen line series with lower states n = 10, 11, 12, and 13 have been detected in a laboratory plasma. The width of the 12-alpha line at 88.7 microns could be measured and was consistent with calculated broadening from elastic electron collisions and quasi-static ion effects.

  3. Stark Broadening of several Ne II, Ne III and O III Spectral Lines for the Stark-B Database

    CERN Document Server

    Dimitrijevic, Milan S; Simic, Zoran; Sahal-Brechot, Sylvie

    2012-01-01

    In order to complete Stark broadening data for Ne II, and O III lines, needed for analysis of stellar atmospheres, we determined, within the semiclassical perturbation method, the missing Stark broadening parameters for the broadening by collisions with protons and ionized helium, for 15 Ne II and 5 O III multiplets. Also, electron, proton, and ionized helium impact broadening parameters for an important Ne II multiplet in the visible part of the spectrum, and for three Ne III multiplets, were calculated. The obtained data will be included in the STARK-B database, which is a part of Virtual Atomic and Molecular Data Center.

  4. Theoretical study of the Stark broadening for Mg IV spectral lines of astrophysical interest

    Science.gov (United States)

    de Andrés-García, I.; You, C.; Alonso-Medina, A.; Colón, C.

    2016-08-01

    Emission lines of Mg IV have been detected in the Far Ultraviolet Spectroscopic Explorer (FUSE) spectrum of LS V +46º21 star and in the Space Telescope Imaging Spectrograph (STIS) spectrum of BD +28º4211 star. This fact justifies our interest in providing spectroscopic parameters of Mg IV. Stark broadening parameters for 169 spectral lines of Mg IV have been calculated by using the Griem semi-empirical approach. The matrix elements used in these calculations has been determined from 13 configurations of Mg IV: 2s12p6, 2s22p4ns (n = 3-5), 2s22p4nd (n = 3-5) and 2s22p45g for even parity and 2s22p5, 2s22p4np (n = 3, 4) and 2s22p4nf (n = 4, 5) for odd parity. Our calculations were made by using the Cowan code. Data are presented for an electron density of 1017 cm-3 and temperatures T = 1.0-10.0 (104 K). Also we present calculated values of transition probabilities for 30 spectral lines and radiative lifetimes corresponding to its upper levels. These values were analyzed using the data found in the literature. Theoretical trends of the Stark broadening parameters versus the temperature for several lines of astrophysical interest are presented.

  5. Self- and CO2-broadened line shape parameters for infrared bands of HDO

    Science.gov (United States)

    Smith, Mary-Ann H.; Malathy Devi, V.; Benner, D. Chris; Sung, Keeyoon; Mantz, Arlan W.; Gamache, Robert R.; Villanueva, Geronimo L.

    2015-11-01

    Knowledge of CO2-broadened HDO line widths and their temperature dependence is required to interpret infrared spectra of the atmospheres of Mars and Venus. However, this information is currently absent in most spectroscopic databases. We have analyzed nine high-resolution, high signal-to-noise spectra of HDO and HDO+CO2 mixtures to obtain broadening coefficients and other line shape parameters for transitions of the ν2 and ν3 vibrational bands located at 7.13 and 2.70 μm, respectively. The gas samples were prepared by mixing equal amounts of high-purity distilled H2O and 99% enriched D2O. The spectra were recorded at different temperatures (255-296 K) using a 20.38 cm long coolable cell [1] installed in the sample compartment of the Bruker IFS125HR Fourier transform spectrometer at the Jet Propulsion Laboratory in Pasadena, CA. The retrieved HDO spectroscopic parameters include line positions, intensities, self- and CO2-broadened half-width and pressure-induced shift coefficients and the temperature dependences for CO2 broadening. These spectroscopic parameters were obtained by simultaneous multispectrum fitting [2] of the same interval in all nine spectra. A non-Voigt line shape with speed dependence was applied. Line mixing was also observed for several transition pairs. Preliminary results compare well with the few other measurements reported in the literature.[1] K. Sung et al., J. Mol. Spectrosc. 162, 124-134 (2010).[2] D. C. Benner et al., J. Quant. Spectrosc. Radiat Transfer 53, 705-721 (1995).The research performed at the College of William and Mary was supported by NASA’s Mars Fundamental Research Program (Grant NNX13AG66G). The research at Jet Propulsion Laboratory, California Institute of Technology, Connecticut College, Langley Research Center, and Goddard Space Flight Center was conducted under contracts and cooperative agreements with the National Aeronautics and Space Administration. RRG is pleased to acknowledge support of this study by the

  6. On quantum-mechanical unified theories of collisional spectral line broadening

    OpenAIRE

    Schuller, F.; Nienhuis, G.

    1982-01-01

    We compare the Baranger-type unified theory of line broadening with a quantum version of the binary-collision approach. For the simple model system of a two-state atom, where both treatments are well-defined, the binary-collision theory results only from the exact formalism after an inversion of an integration variable in an integral equation. On the other hand, the binary-collision theory is applicable to more general systems. In the limiting cases of the impact and the quasistatic theories,...

  7. Refinement of the semiclassical theory of the Stark broadening of hydrogen spectral lines in plasmas

    International Nuclear Information System (INIS)

    Stark broadening (SB) of hydrogen, deuterium, and tritium lines (H-lines) is an important diagnostic tool for many applications. The most “user-friendly” are semiclassical theories of the SB of H-lines: their results can be expressed analytically in a relatively simple form for any H-line. The simplest semiclassical theory is the so-called Conventional Theory (CT), which is frequently referred to as Griem's theory. While by now there are several significantly more advanced semiclassical “non-CT” theories of the SB, Griem's CT is still used by a number of groups performing laboratory experiments or astrophysical observations for the comparison with their experimental or observational results. In the present study we engage unexplored capabilities of the CT for creating analytically a more accurate CT. First, we take into account that the perturbing electrons actually do not move as free particles: rather they move in a dipole potential V=〈R〉·r/r3, where r is the radius-vector of the perturbing electrons and 〈R〉 is the mean value of the radius vector of the atomic electron. Second, Griem's definition of the so-called Weisskopf radius was not quite accurate. Third, in his book of year 1974, Griem suggested changing so-called strong collision constant without changing the Weisskopf radius, while in reality the choices of the Weisskopf radius and of the strong collision constant are interrelated. We show that the above refinements of the CT increase the electron broadening – especially for warm dense plasmas emitting H-lines. By comparison with benchmark experiments concerning the Hα line we demonstrate that the effect of the ion dynamics (neglected in any CT) might be slightly smaller than previously thought, while the effect of the acceleration of perturbing electrons by the ion field in the vicinity of the radiating atom (neglected in any CT) might be greater than previously thought. - Highlights: • Perturbing electrons actually

  8. Pulse-driven nonlinear Alfv\\'en waves and their role in the spectral line broadening

    CERN Document Server

    Chmielewski, P; Murawski, K; Musielak, Z E

    2012-01-01

    We study the impulsively generated non-linear Alfv\\'en waves in the solar atmosphere, and describe their most likely role in the observed non-thermal broadening of some spectral lines in solar coronal holes. We solve numerically the time-dependent magnetohydrodynamic equations to find temporal signatures of large-amplitude Alfv\\'en waves in the model atmosphere of open and expanding magnetic field configuration, with a realistic temperature distribution. We calculate the temporally and spatially averaged, instantaneous transversal velocity of non-linear Alfv\\'en waves at different heights of the model atmosphere, and estimate its contribution to the unresolved non-thermal motions caused by the waves. We find that the pulse-driven nonlinear Alfv\\'en waves with the amplitude $A_{\\rm v}$=50 km s$^{-1}$ are the most likely candidates for the non-thermal broadening of Si VIII $\\lambda$1445.75 \\AA\\ line profiles in the polar coronal hole as reported by Banerjee et al. (1998). We also demonstrate that the Alfv\\'en w...

  9. Magnetic Turbulence and Line Broadening in Simulations of Lyman-Alpha Absorption

    Science.gov (United States)

    Gurvich, Alex; Burkhart, Blakesley K.; Bird, Simeon

    2016-01-01

    We use the Illustris cosmological AREPO simulations to study the effects of gas turbulence and magnetic fields on measurements from the Lyman-Alpha forest. We generate simulated Lyman-Alpha spectra and plot the distributions of Column Density (CDD) and Doppler Width (b) both by adhering to the canonical method of fitting Voigt profiles to absorption lines and by directly measuring the column density and equivalent widths from snapshot data .We investigate the effects of additional unresolved gas turbulence in Illustris by adding an additional broadening term to the line profiles to mimic turbulent broadening. When we do this, we find a measurable effect in the CDD and an offset in the mean of the b distribution corresponding to the additional turbulence. We also compare different MHD runs in AREPO we find that the CDD can measurably differentiate between magnetic seed field at redshifts as low as z=0.1, but we do not find that the b distribution is affected at a detectable level. Our work suggests that the effects of turbulence and magnetic fields from z=2-0.1 can potentially be measured with these diagnostics. This work was supported in part by the NSF REU and DoD ASSURE programs under NSF grant no. 1262851 and by the Smithsonian Institution.

  10. Fluctuation broadening of the plasma resonance line in the vortex liquid state of layered superconductors

    International Nuclear Information System (INIS)

    The Josephson plasma resonance (JPR) provides a sensitive probe of vortex states in layered superconductors. We demonstrate that in the case of weak damping in the liquid phase, broadening of the JPR line is caused mainly by random Josephson coupling arising from the density fluctuations of pancake vortices. In this case the JPR line has the universal shape, which is determined only by parameters of the superconductors and temperature. This mechanism gives a natural explanation for the experimentally observed asymmetric lineshape. The tail at high frequencies arises due to mixing of the propagating plasma modes by random Josephson coupling, while the tail at small frequencies is caused by the localized plasma modes originating from a rare fluctuation suppression of the Josephson coupling in large areas. copyright 1999 The American Physical Society

  11. Shift and broadening of emission lines in Nd$^{3+}$:YAG laser crystal influenced by input energy

    Indian Academy of Sciences (India)

    POURMAND SEYED EBRAHIM; REZAEI GHASEM

    2016-06-01

    Spectroscopic properties of the flashlamp-pumped Nd$^{3+}$:YAG laser as a function of input energy were studied over the range of 18–75 J. The spectral widths and shifts of quasi-three-level and four-level inter-Stark emissions within the respective intermanifold transitions of $^4$F$_{3/2}$ $\\rightarrow$ $^{4}$I$_{9/2} $ and $^{4}$F$_{3/2}$ $\\rightarrow$ $^{4}$I$_{11/2}$ were investigated. The emission lines of $^{4}$F$_{3/2}$ $\\rightarrow$ $^{4}$I$_{9/2}$ shifted towards longer wavelength (red shift) and broadened, while the positions and linewidths of the $^{4}$F$_{3/2}$ $\\rightarrow$ $^{4}$I$_{11/2}$ transition lines remained constant by increasing the pumping energy. This is attributed to the thermal population as well as one-phonon and multiphonon emission processes in the ground state. This phenomenon degrades the output performance of the lasers.

  12. Plasma motions and non-thermal line broadening in flaring twisted coronal loops

    Science.gov (United States)

    Gordovskyy, M.; Kontar, E. P.; Browning, P. K.

    2016-05-01

    Context. Observation of coronal extreme ultra-violet (EUV) spectral lines sensitive to different temperatures offers an opportunity to evaluate the thermal structure and flows in flaring atmospheres. This, in turn, can be used to estimate the partitioning between the thermal and kinetic energies released in flares. Aims: Our aim is to forward-model large-scale (50-10 000 km) velocity distributions to interpret non-thermal broadening of different spectral EUV lines observed in flares. The developed models allow us to understand the origin of the observed spectral line shifts and broadening, and link these features to particular physical phenomena in flaring atmospheres. Methods: We use ideal magnetohydrodynamics (MHD) to derive unstable twisted magnetic fluxtube configurations in a gravitationally stratified atmosphere. The evolution of these twisted fluxtubes is followed using resistive MHD with anomalous resistivity depending on the local density and temperature. The model also takes thermal conduction and radiative losses in the continuum into account. The model allows us to evaluate average velocities and velocity dispersions, which would be interpreted as non-thermal velocities in observations, at different temperatures for different parts of the models. Results: Our models show qualitative and quantitative agreement with observations. Thus, the line-of-sight (LOS) velocity dispersions demonstrate substantial correlation with the temperature, increasing from about 20-30 km s-1 around 1 MK to about 200-400 km s-1 near 10-20 MK. The average LOS velocities also correlate with velocity dispersions, although they demonstrate a very strong scattering compared to the observations. We also note that near footpoints the velocity dispersions across the magnetic field are systematically lower than those along the field. We conclude that the correlation between the flow velocities, velocity dispersions, and temperatures are likely to indicate that the same heating

  13. Stark Broadening of High-order Radio Recombination Lines toward the Orion Nebula

    Science.gov (United States)

    Alexander, J.; Gulyaev, S.

    2016-09-01

    We report the results of observations and analyses of 41 {{Δ }}n=1,\\ldots ,5 hydrogen radio recombination lines from the Orion nebula (M42) at 5.5 to 6.5 GHz, with a spectral sensitivity (channel-to-channel standard deviation) of ≈ 2 {mJy}. Observations were conducted at the Australia Telescope Compact Array. A 1 GHz bandwidth allowed simultaneous detection of up to 11 spectral lines of equal {{Δ }}n that were stacked to enable accurate measurement of line widths. Collisional widths in the range of principal quantum numbers n from 100 to 179 are found to be consistent with predictions of electron impact Stark broadening theory. An Orion nebula model with density inhomogeneities (clumps) and gradients of temperature and density is consistent with our data. We reanalyze the data of Smirnov et al. and Bell et al. and find excellent agreement between all statistically significant measurements and theory. Our findings confirm the absence of line narrowing for n = 100...179.

  14. Plasma density characterization at SPARC_LAB through Stark broadening of Hydrogen spectral lines

    Science.gov (United States)

    Filippi, F.; Anania, M. P.; Bellaveglia, M.; Biagioni, A.; Chiadroni, E.; Cianchi, A.; Di Giovenale, D.; Di Pirro, G.; Ferrario, M.; Mostacci, A.; Palumbo, L.; Pompili, R.; Shpakov, V.; Vaccarezza, C.; Villa, F.; Zigler, A.

    2016-09-01

    Plasma-based acceleration techniques are of great interest for future, compact accelerators due to their high accelerating gradient. Both particle-driven and laser-driven Plasma Wakefield Acceleration experiments are foreseen at the SPARC_LAB Test Facility (INFN National Laboratories of Frascati, Italy), with the aim to accelerate high-brightness electron beams. In order to optimize the efficiency of the acceleration in the plasma and preserve the quality of the accelerated beam, the knowledge of the plasma electron density is mandatory. The Stark broadening of the Hydrogen spectral lines is one of the candidates used to characterize plasma density. The implementation of this diagnostic for plasma-based experiments at SPARC_LAB is presented.

  15. Breakdown of the line-space concept in Stark broadening of spectral lines by plasmas

    International Nuclear Information System (INIS)

    A study is presented that proves that the standard model for calculation of line shapes, e.g., transitions from nl to n'l' must be modified to include levels from higher principal quantum number manifolds, ndouble-prime>n'. This becomes particularly important in the study of transitions without central components, exhibiting a central minimum, as the effect of the higher ndouble-prime states is to cause a filling in of the central minimum. An analytic derivation is provided and detailed calculations are performed to illustrate the effect. copyright 1998 The American Physical Society

  16. Measurement of multiplet intensities and noble gas-broadened line widths in the nu 3 fundamental of methane

    Science.gov (United States)

    Varanasi, P.; Pugh, L. A.; Bangaru, B. R. P.

    1974-01-01

    Presented integrated intensity data at 300 K for J multiplets between P(11) and R(11) in the nu-3 fundamental of C-12 methane are shown to be in good agreement with most previously published pertinent values. Also, line widths measured at 100 K, 130 K, 190 K, 250 K, and 300 K for R(0), R(1), and R(2) broadened by He, Ne, and Ar are presented, and the line-width temperature dependence is discussed for the three cases of broadening.

  17. Diagnosing galactic feedback with the line broadening in the low redshift Lyman-alpha forest

    CERN Document Server

    Viel, M; Bolton, J S; Kim, T -S; Puchwein, E; Nasir, F; Wakker, B P

    2016-01-01

    We compare the low redshift (z ~ 0.1) Lyman-alpha forest from hydrodynamical simulations with data from the Cosmic Origin Spectrograph (COS). We find tension between the observed number of lines with b-parameters in the range 25-45 km/s and the predictions from simulations that incorporate either vigorous feedback from active galactic nuclei or that exclude feedback altogether. The gas in these simulations is, respectively, either too hot to contribute to the Lyman-alpha absorption or too cold to produce the required line widths. Matching the observed b-parameter distribution therefore requires feedback processes that thermally or turbulently broaden the absorption features without collisionally (over-)ionising hydrogen. This suggests the Lyman-alpha forest b-parameter distribution is a valulable diagnostic of galactic feedback in the low redshift Universe. We furthermore confirm the low redshift Lyman-alpha forest column density distribution is better reproduced by an ultraviolet background with an HI photo-...

  18. [Determination of relative error of pressure-broadening linewidth for the experimentally indistinguishable overlapped spectral lines with Voigt profile].

    Science.gov (United States)

    Lin, Jie-Li; Huang, Yi-Qing; Lu, Hong

    2005-01-01

    The simulation and fitting of the overlapped spectral lines with Voigt profile were presented in this paper. The relative errors epsilon of the fitted pressure-broadening linewidth when taking the overlapped spectral line as one spectrum were discussed in detail. The relationship between such error and the two spectral lines center distance deltav0, and theoretical pressure-broadening linewidth deltav(L)0 were analyzed. Epsilon is found to be very large and the relationship between epsilon and deltav0, deltav(L)0 is very complicated when the value of pressure-broadening linewidth is considerably less than that of Dopplerian one deltavD. When deltav(L)0 is comparative to deltaVD the relationship between epsilon and deltav0 is close to the smooth two-order polynomial curve. However, the slop of this curve is negative while deltav(L)0 is smaller than deltavD and is positive when larger. Generally, epsilon decreases with the increase of proportion of deltav(l)0 to the whole spectral linewidth. All the above conclusion and corresponding data are the significant reference to determine the precise pressure-broadening coefficient from the experimentally indistinguishable overlapped spectrum, as well as to correct the fitted pressure-broadening linewidth. PMID:15852837

  19. Pressure broadening, -shift, speed dependence and line mixing in the ν3 rovibrational band of N2O

    Science.gov (United States)

    Loos, Joep; Birk, Manfred; Wagner, Georg

    2015-01-01

    In this paper, we report measured air-broadening, -shift, speed dependence and Rosenkranz line mixing parameters for the ν3 fundamental rovibrational band of N2O. A Bruker IFS 125HR Fourier transform spectrometer was used with a White-type multipass absorption cell with 46.4 m absorption path length to measure four ambient temperature air-broadened absorption spectra at total pressures ranging from 100 to 1000 mbar. A multispectrum fitting technique was used to retrieve parameters up to |m|=40 (m=-J″ and m=J″+1 for the P and R branch, respectively) utilizing the partially correlated quadratic speed-dependent hard collision model including Rosenkranz line mixing. Speed dependence of the broadening parameter as well as line mixing could be observed in the spectra. The broadening parameters are compared to HITRAN2012, where deviations can be ascribed to the influence of neglecting speed dependence effects in spectra analyses when using the Voigt line profile. The line mixing coefficients show a smooth dependence on m.

  20. Line broadening caused by Coulomb carrier-carrier correlations and dynamics of carrier capture and emission in quantum dots

    DEFF Research Database (Denmark)

    Uskov, Alexander V; Magnúsdóttir, Ingibjörg; Tromborg, Bjarne;

    2001-01-01

    Mechanisms of pure dephasing in quantum dots due to Coulomb correlations and the dynamics of carrier capture and emission are suggested, and a phenomenological model for the dephasing is developed. It is shown that, if the rates of these capture and emission processes are sufficiently high, signi......, significant homogeneous line broadening of the order of several meV can result....

  1. Observations of Relativistically Broadened Iron Kalpha Lines From Stellar Mass Black Holes

    Science.gov (United States)

    Tomsick, John

    2016-04-01

    The measurement of Doppler broadened and gravitationally redshifted iron emission lines from accreting black holes has been used to measure the inner radius of the optically thick disk (Rin). At high mass accretion rates, when the disk is at or close to the Innermost Stable Circular Orbit (ISCO), a determination of Rin provides a constraint on the spin of the black hole. Measuring Rin can also provide information about whether the disk is truncated or not, and this is especially important for understanding the relationship between the disk and the steady jet in the hard state. Over the past few years, the Nuclear Spectroscopic Telescope Array (NuSTAR) has provided improved measurements due to its combination of bandpass (3-79 keV), good energy resolution, and high throughput. In this presentation, we discuss NuSTAR results for a number of stellar mass black holes (e.g., Cyg X-1, GX 339-4, and GRS 1739-278). While these observations have been successful in obtaining measurements of Rin, the improved spectra have also provided extra information about the source geometry and the inner disk inclination, which we will discuss.

  2. Coherent population trapping resonances at lower atomic levels of Doppler broadened optical lines

    Energy Technology Data Exchange (ETDEWEB)

    Şahin, E; Hamid, R; Çelik, M [National Metrology Institute of Turkey, Gebze, Kocaeli (Turkey); Özen, G [Istanbul Technical University, Faculty of Science and Letters, Engineering Physics Department Maslak, Istanbul (Turkey); Izmailov, A Ch [Institute of Physics, Azerbaijan National Academy of Sciences, H. Javid av. 33, Baku, Az-1143 (Azerbaijan)

    2014-11-30

    We have detected and analysed narrow high-contrast coherent population trapping (CPT) resonances, which are induced in absorption of a weak monochromatic probe light beam by counterpropagating two-frequency pump radiation in a cell with rarefied caesium vapour. The experimental investigations have been performed by the example of nonclosed three level Λ-systems formed by spectral components of the D{sub 2} line of caesium atoms. The applied method allows one to analyse features of the CPT phenomenon directly at a given low long-lived level of the selected Λ-system even in sufficiently complicated spectra of atomic gases with large Doppler broadening. We have established that CPT resonances in transmission of the probe beam exhibit not only a higher contrast but also a much lesser width in comparison with well- known CPT resonances in transmission of the corresponding two-frequency pump radiation. The results obtained can be used in selective photophysics, photochemistry and ultra-high resolution atomic (molecular) spectroscopy. (laser applications and other topics in quantum electronics)

  3. A comparative study of the broadening effect on rotational lines by methane and noble gases

    International Nuclear Information System (INIS)

    Line broadening measurements for the mixtures HCl-CH4 and HCl-CD4 have been performed and the results of these experiments are reported. Current theoretical models for the systems studied are briefly discussed. In order to identify specific effects the authors have tried to find a generalisation for linewidth cross-sections for the HCl-noble gas systems. This is done in the spirit of the well known corresponding state treatment in statistical mechanics in an attempt to find, in terms of reduced variables, a generalised intermolecular potential for these systems. Extensive calculations on the HCl-Ar and HCl-Kr intermolecular potentials, as derived from linewidth measurements, are reported in an attempt to extract a more exact potential for these systems. The results are compared with other recent results from the literature. The use of a semi-empirical method for the evaluation of the experimental data is described. This empirical method has been used in a comparison between the HCl-noble gas experiments and the present experiments of HCl-methane. The possibility of splitting the observed data into a 'noble gas' part and a 'extra' part due to the intermolecular interactions which result from the coupling of the HCl rotations with the internal degrees of freedom of the methane molecules is discussed. (Auth.)

  4. Theoretical Calculations of Thermal Broadenings and Transition Probabilities of R, R' and B Line-Groups for Ruby

    Institute of Scientific and Technical Information of China (English)

    MA Dong-Ping; LIU Yan-Yun; CHEN Ju-Rong

    2001-01-01

    On the basis of the unified calculation of the thermal shifts of R1 line, R2 line and ground-state-splitting transition probabilities of direct and Raman processes have theoretically been calculated. The thermal broadenings of R,The theoretically predicted transition probabilities are in good agreement with the experimental ones.PACS numbers: 71.70.Ch, 78.20.Nv, 63.20.Mt, 63.20.Kr

  5. Dilute RKKY model for NMR line broadening in the hidden-order state of URu2Si2

    Science.gov (United States)

    Walstedt, R. E.; Kambe, S.; Tokunaga, Y.; Sakai, H.

    2016-01-01

    A well-known analytic model for Lorentzian broadening of metallic NMR lines by dilute localized magnetic centers embedded in a lattice has been applied to the case of the twofold-symmetry magnetism in URu2Si2 reported by R. Okazaki et al. [Science 331, 439 (2011), 10.1126/science.1197358]. The observed Lorentzian spectra are accounted for with a simple formula giving the 29Si NMR linewidth in terms of the susceptibility of the magnetic-broadening centers and a Ruderman-Kittel-Kasuya-Yosida (RKKY) coupling parameter. The concentration of such centers is estimated as c ˜0.01 . A numerical simulation of these effects confirms Lorentzian broadening with no measurable NMR shift and a width in reasonable agreement with the analytical model. The simulation shows further that domain effects on these spectra are largely absent. A four-site extended model of the broadening centers gives an estimate of the twofold susceptibility within a factor of 2 of the torque value of the susceptibility. Hypothetical superlattice effects are shown to be easily smoothed over by convolution with background Lorentzian broadening.

  6. Stark broadening of B IV lines for astrophysical and laboratory plasma research

    CERN Document Server

    Dimitrijević, Milan S; Simić, Zoran; Kovačević, Andjelka; Sahal-Bréchot, Sylvie

    2013-01-01

    Stark broadening parameters for 36 multiplets of B IV have been calculated using the semi-classical perturbation formalism. Obtained results have been used to investigate the regularities within spectral series and temperature dependence.

  7. Exact trajectory in semiclassical line broadening and line shifting calculation test for H2-He Q(1) line

    International Nuclear Information System (INIS)

    The semiclassical model RB (Robert, D. and Bonamy, J. (Journal de Physique (Paris), 1979, 40, 923 for calculation of line width and line shift has been used in many applications. It contains an approximate 'parabolic' trajectory. Bykov, A.D. et al, Atmospheric and Oceanic Optics (1992) 5, 587, have recently proposed an analytical expression for an exact treatment of the classical path. This paper analyses the consequence of introducing the exact trajectory within the RB model for the H2-He Q(1) line chosen as a simple test. Moreover, a comparison with results of exact close-coupling calculations is also given for this molecular system. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  8. A spectrometer for the measurement of the Doppler broadening of the annihilation line with efficient reduction of background

    International Nuclear Information System (INIS)

    Following Lynn and the suggestion made by MacKenzie we describe a Doppler broadening (DB) spectrometer with efficient reduction of the background (BG). The simple experimental set-up achieved a peak to the BG ratio for the annihilation line of the order 1000:1. In this work, attention is given to the problem of the BG correction under the annihilation line, which has not been described in the literature. Measurements of Doppler profile of the annihilation line in Ni, Cu and a single crystal of Si are presented as an illustration of the advantage of the applications of the suggested BG reduction and correction technique. (orig.)

  9. Stark broadening of Mg I and Mg II spectral lines and Debye shielding effect in laser induced plasma

    Energy Technology Data Exchange (ETDEWEB)

    Cvejić, M.; Gavrilović, M.R.; Jovićević, S. [Institute of Physics, University of Belgrade, 11081 Belgrade, P.O. Box 68 (Serbia); Konjević, N., E-mail: nikruz@ff.bg.ac.rs [Faculty of Physics, University of Belgrade, 11001 Belgrade, P.O. Box 368 (Serbia)

    2013-07-01

    We report Stark broadening parameters for three Mg I lines and one Mg II line in the electron number density range (0.67–1.09) · 10{sup 17} cm{sup −3} and electron temperature interval (6200–6500) K. The electron density is determined from the half width of hydrogen impurity line, the H{sub α}, while the electron temperature is measured from relative intensities of Mg I or Al II lines using Boltzmann plot technique. The plasma source was induced by Nd:YAG laser radiation at 1.06 μm having pulse width 15 ns and pulse energy 50 mJ. Laser induced plasma is generated in front of a solid state surface. High speed photography is used to determine time of plasma decay with good homogeneity and then applied line self-absorption test and Abel inversion procedure. The details of data acquisition and data processing are described and illustrated with typical examples. The experimental results are compared with two sets of semiclassical calculations and the results of this comparison for Mg I lines are not unambiguous while for Mg II 448.1 nm line, the results of Dimitrijević and Sahal-Bréchot calculations agree well with our and other experimental results in the temperature range (5000–12,000) K and these theoretical results are recommended for plasma diagnostic purposes. The study of line shapes within Mg I 383.53 nm multiplet shows that the use of Debye shielding correction improves the agreement between theoretical and experimental Stark broadening parameters. - Highlights: • Stark broadening parameters for three Mg I and one Mg II line. • Comparison of Stark parameters with other experimental and theoretical results. • Recommendation of Mg II 448.1 nm line for plasma diagnostics. • Influence of Debye shielding effect to line widths of Mg I 383.53 nm multiplet. • Application of laser induced plasma for Stark broadening parameters measurement.

  10. Broadening of CO2 lines in the 4.3 μm region by H2O

    Science.gov (United States)

    Delahaye, T.; Landsheere, X.; Pangui, E.; Huet, F.; Hartmann, J.-M.; Tran, H.

    2016-08-01

    Transmission spectra of CO2 highly diluted in water vapor have been recorded at 50 and 95 °C for four pressures between 0.02 and 0.1 atm using a high resolution Fourier Transform spectrometer. The collisional (Lorentz) widths of many lines of the ν3 band (and of some of the ν3 + ν2 - ν2 hot band) have been retrieved from each spectrum through fits using Voigt line shapes. Our result are about 4% lower than the values recommended in a previous study but they confirm the relative variations of the line broadening on the rotational quantum numbers. We also provide the first determination of H2O-induced line shifts of CO2 lines.

  11. Air pressure broadening and shifting of high-J lines of (00011) 12C16O2

    International Nuclear Information System (INIS)

    The absorption spectra of carbon dioxide (isotope 626, natural abundance in air, ambient temperature) have been studied at total pressures 68-570 Torr with spectral resolution 0.003-0.005 cm-1. The spectra were measured in the spectral domain of 2273-2393 cm-1 by FTIR spectrometer Bruker IFS 125 HR equipped with White-type multipass cell (6.4-41.6 m) and with a cell having 10 cm optical path length. Pressure broadening and shift coefficients were obtained from a series of spectra by means of a nonlinear least-squares spectral fitting technique for the lines of the (00011) <- (00001) band with rotational quantum number up to J=82. For fitting of the individual line shapes, we used the Voigt profile with pre-calculated Doppler broadening parameter. The experimental pressure broadening and shift coefficients are compared with the values available in spectroscopic databases HITRAN 2008 and Carbon Dioxide Spectroscopic Databank (CDSD-296) and with other experimental values reported in the literature.

  12. A comparison between different X-ray diffraction line broadening analysis methods for nanocrystalline ball-milled FCC powders

    Energy Technology Data Exchange (ETDEWEB)

    Soleimanian, V. [Shahrekord University, Department of Physics, Faculty of Sciences, P.O. Box 115, Shahrekord (Iran, Islamic Republic of); Shahrekord University, Nanotechnology Research Center, Shahrekord (Iran, Islamic Republic of); Mojtahedi, M. [Pooya Gharb Branch of University of Applied Science and Technology, Department of Materials Engineering, Kermanshah (Iran, Islamic Republic of)

    2015-06-15

    The microstructural characteristics of aluminum, copper and nickel powders are investigated using different X-ray diffraction line broadening analysis approaches. Prior to analysis, the powders were ball-milled to produce a nanocrystalline structure with high density of probable types of lattice defects. A variety of methods, including Scherrer, Williamson-Smallman, Williamson-Hall, Warren-Averbach, modified Williamson-Hall, modified Warren-Averbach, Rietveld refinement and whole powder pattern modeling (WPPM) approaches are applied. In this way, microstructural characteristics such as crystallite size, microstrain, dislocation density, effective outer cut-off radius of dislocations and the probability of twining and stacking faults are calculated. On the other hand, the results of conventional and advanced line broadening analysis methods are compared. It is revealed that the density of linear and planar defects in the mechanically deformed aluminum powder is significantly smaller than that of copper and nickel, as well as the level of anisotropic strain broadening. Moreover, the WPPM procedure provided a better profile fitting with more accurate results. (orig.)

  13. Broadening of the Spectral Atomic Lines Analysis in High Density Argon Corona Plasma by Using Voigt Profile

    Science.gov (United States)

    Nur, M.; Bonifaci, N.; Denat, A.; Atrazhev, V. M.

    2015-06-01

    Studies of spectrum emission from high density argon plasma corona has been done. The analysis of the boardening of spectral atomic lines of Ar-I profile has been curried out by using an empirical approximation based on a Voigt profile. Full-width at half-maximum (FWHM) of the spectral-lines of 763.5 nm has been determined from atmospheric pressure until liquid state. The study liquid argon was curried out in a variation of temperature from K to 151.2 K and hydrostatics pressure from 2.1 MPa to 6.4 MPa. These pressure gives the densities N∞ (i.e. density very far from ionization zone) a variation from 1.08 1022 to 2.11 1022 cm-3. FWHM of Voigt approximation (Wv) of the line 763,5 nm of 'Ar I for: the emission lamp very low pressure (Wv = 0,160 nm) and our corona discharge at a pressure of MPa (Wv = 0,67 nm) and at a pressure of 9,5 MPa (Wv = 1,16 nm). In gas, corona plasma has been generated from 0.1 MPa to 9.5 MPa. We found that the broadening spectral line increase by increasing densities both for. the spectral-lines of 763.5 nm and 696.5 nm. We concluded that broadening of spectrum cause of Van der Waals force.

  14. Pressure broadening measurement of submillimeter-wave lines of O3

    Science.gov (United States)

    Yamada, M. M.; Amano, T.

    2005-10-01

    The pressure broadening coefficients and their temperature dependences for two submillimeter-wave transitions of ozone, one being monitored with Odin and the other to be monitored with JEM/SMILES and EOS-MLS, have been determined by using a BWO based submillimeter-wave spectrometer. The measurements have also been extended to one of the symmetric isotopic species, 16O18O16O. The isotopic species is observed in natural abundance and as a consequence the temperature dependence is not determined due to weak signal intensity. The pressure broadening parameters are determined with better than 1% accuracy, while the temperature dependence exponents are obtained within 1.5 3% accuracy for the normal species transitions.

  15. Pressure broadening measurement of submillimeter-wave lines of O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, M.M. [Institute for Astrophysics and Planetary Sciences, Ibaraki University, 2-1-1 Bunkyo, Mito 310-8512 (Japan); Amano, T. [Institute for Astrophysics and Planetary Sciences, Ibaraki University, 2-1-1 Bunkyo, Mito 310-8512 (Japan)]. E-mail: amano@mx.ibaraki.ac.jp

    2005-10-01

    The pressure broadening coefficients and their temperature dependences for two submillimeter-wave transitions of ozone, one being monitored with Odin and the other to be monitored with JEM/SMILES and EOS-MLS, have been determined by using a BWO based submillimeter-wave spectrometer. The measurements have also been extended to one of the symmetric isotopic species, {sup 16}O{sup 18}O{sup 16}O. The isotopic species is observed in natural abundance and as a consequence the temperature dependence is not determined due to weak signal intensity. The pressure broadening parameters are determined with better than 1% accuracy, while the temperature dependence exponents are obtained within 1.5-3% accuracy for the normal species transitions.

  16. EUV Non-thermal Line Broadening and High-energy particles during Solar Flares

    CERN Document Server

    Kawate, Tomoko

    2013-01-01

    We have studied the relationship between the location of EUV nonthermal broadening and high-energy particles during the large flares by using EUV imaging spectrometer onboard {\\it Hinode}, Nobeyama Radio Polarimeter, Nobeyama Radioheliograph, and Atmospheric Imaging Assembly onboard {\\it Solar Dynamic Observatory}. We have analyzed the five large flare events which contain thermal rich, intermediate, and thermal poor flares classified by the definition discussed in the paper. We found that, in the case of thermal rich flares, the nonthermal broadening of \\ion{Fe}{24} occurred at the top of the flaring loop at the beginning of the flares. The source of the 17 GHz microwave is located at the footpoint of the flare loop. On the other hand, in the case of intermediate/thermal poor flares, the nonthermal broadening of \\ion{Fe}{24} occurred at the footpoint of the flare loop at the beginning of the flares. The source of the 17 GHz microwave is located at the top of the flaring loop. We discussed the difference betw...

  17. Solving the line-shape problem with speed-dependent broadening and shifting and with Dicke narrowing. I. Formalism

    International Nuclear Information System (INIS)

    In this paper, we present a formalism for the exact calculation of spectral profile of an isolated line undergoing speed-dependent collisional broadening and shifting and Dicke narrowing. It is couched in the language of the density matrix as in the closely related fields of transport phenomena, laser physics, and nonlinear optics. The formalism is ab intio in spirit, permitting the calculation of the line shape starting only from a given interaction potential. The line shape is obtained by solving a transport/relaxation equation for the off-diagonal element of the density matrix, a macroscopic quantity. The collision operator in the transport/relaxation equation, which is determined from the (microscopic) interaction between the active molecule and the perturber, is presumed known

  18. Modelling dislocation-induced anisotropic line broadening in Rietveld refinements using a Voigt function. I. General Principles

    Energy Technology Data Exchange (ETDEWEB)

    Wu, E.; Gray, E.M.A. [Griffith Univ., Brisbane, QLD (Australia). School of Science; Kisi, E.H

    1998-06-01

    For pt.II see ibid., vol.31, p.363-8, 1998. The theory of dislocation-induced X-ray or neutron diffraction line broadening developed by Krivoglaz et al. and Wilkens has been adapted for Rietveld refinement of the powder diffraction profile by fitting a Voigt function to each peak. Information on both the type of slip system and the density of dislocations in the crystallites may then be found by evaluating the shape parameter and the index-dependent breadth of the Voigt function. (orig.) 31 refs.

  19. Atom Resonance Lines for Modeling Atmosphere: Studies of Pressure-Broadening of Alkali Atom Resonance Lines for Modeling Atmospheres of Extrasolar Giant Planets and Brown Dwarfs

    Science.gov (United States)

    Hasan, Hashima (Technical Monitor); Kirby, K.; Babb, J.; Yoshino, K.

    2005-01-01

    We report on progress made in a joint program of theoretical and experimental research to study the line-broadening of alkali atom resonance lines due to collisions with species such as helium and molecular hydrogen. Accurate knowledge of the line profiles of Na and K as a function of temperature and pressure will allow such lines to serve as valuable diagnostics of the atmospheres of brown dwarfs and extra-solar giant planets. A new experimental apparatus has been designed, built and tested over the past year, and we are poised to begin collecting data on the first system of interest, the potassium resonance lines perturbed by collisions with helium. On the theoretical front, calculations of line-broadening due to sodium collisions with helium are nearly complete, using accurate molecular potential energy curves and transition moments just recently computed for this system. In addition we have completed calculations of the three relevant potential energy curves and associated transition moments for K - He, using the MOLPRO quantum chemistry codes. Currently, calculations of the potential surfaces describing K-H2 are in progress.

  20. Numerical experiments on the broadening of emission lines formed in a disk

    International Nuclear Information System (INIS)

    The shapes of emission lines formed from a thin, narrow disk inclined to the plane of the sky are investigated. Where the ratio of the velocity of rotation v to the intrinsic line width sigma is greater than about 2.0, the profile may become double-peaked. Where v is comparable to or smaller than 2 sigma, the line is single-peaked. A solid disk always presents a single-peaked profile. Increasing the inclination of the disk to the line of sight increases the width of the line. The differing widths of the emission lines in stars of the same WN subtype may result from differing values of v, sigma, and the inclination of the disk to the plane of the sky. If the disk has a large hole in its middle, the intensity of the emission line is reduced from what it would be for a solid disk or for one with a small hole. 21 refs

  1. Photoluminescence fatigue and inhomogeneous line broadening in semi-insulating Tl6SeI4 single crystals

    Science.gov (United States)

    Kostina, S. S.; Peters, J. A.; Lin, W.; Chen, P.; Liu, Z.; Wang, P. L.; Kanatzidis, M. G.; Wessels, B. W.

    2016-06-01

    Photoluminescence (PL) properties of semi-insulating Tl6SeI4 have been investigated. A broad emission band centered at 1.63 ± 0.02 eV was observed in all samples. The PL emission band is excitonic in nature and is tentatively attributed to a bound exciton emission. PL fatigue (a reduction in PL intensity under prolonged laser excitation) was always observed. The amount of PL fatigue depended on excitation power and temperature. PL fatigue kinetics are described by a stretched exponential with nominal lifetimes in the 10–265 s range. The recovery of the PL occurred within a few seconds of light cessation. The magnitude of PL fatigue in different samples correlated with inhomogeneous line broadening of the 1.63 eV emission band, such that broader bands exhibited more fatigue. An additional luminescence band centered at 1.78 eV was observed which increased in intensity under prolonged laser irradiation. The fatigue phenomenon is tentatively attributed to two mechanisms—the formation of photo-induced defects and the formation of quasi-stable particles. Both of these mechanisms introduce additional radiative and non-radiative recombination channels that lead to a decrease in the PL intensity under prolonged laser irradiation. Since inhomogeneous line broadening and PL fatigue are related to the concentration of defects or impurities, the measurement of these two parameters is an effective method to screen sample quality.

  2. Photoluminescence fatigue and inhomogeneous line broadening in semi-insulating Tl6SeI4 single crystals

    International Nuclear Information System (INIS)

    Photoluminescence (PL) properties of semi-insulating Tl6SeI4 have been investigated. A broad emission band centered at 1.63 ± 0.02 eV was observed in all samples. The PL emission band is excitonic in nature and is tentatively attributed to a bound exciton emission. PL fatigue (a reduction in PL intensity under prolonged laser excitation) was always observed. The amount of PL fatigue depended on excitation power and temperature. PL fatigue kinetics are described by a stretched exponential with nominal lifetimes in the 10–265 s range. The recovery of the PL occurred within a few seconds of light cessation. The magnitude of PL fatigue in different samples correlated with inhomogeneous line broadening of the 1.63 eV emission band, such that broader bands exhibited more fatigue. An additional luminescence band centered at 1.78 eV was observed which increased in intensity under prolonged laser irradiation. The fatigue phenomenon is tentatively attributed to two mechanisms—the formation of photo-induced defects and the formation of quasi-stable particles. Both of these mechanisms introduce additional radiative and non-radiative recombination channels that lead to a decrease in the PL intensity under prolonged laser irradiation. Since inhomogeneous line broadening and PL fatigue are related to the concentration of defects or impurities, the measurement of these two parameters is an effective method to screen sample quality. (paper)

  3. The Nature of Line Broadening in Thermally Detected 57FeFe NMR

    International Nuclear Information System (INIS)

    57FeFe with isotopic concentrations from 15 to 95% is studied using NMR thermally detected by nuclear orientation. Lines are found to be consistently homogeneous. The contrast with previous inhomogeneous 57FeFe lines from Moessbauer detected NMR is explained by differences in radio frequency field strength.

  4. Stark broadening data for spectral lines of rare-earth elements: Nb III

    CERN Document Server

    Simić, Zoran; Popović, Luka Č

    2013-01-01

    The electron-impact widths for 15 doubly charged Nb ion lines have been theoretically determined by using the modified semiempirical method. Using the obtained results, we considered the influence of the electron-impact mechanism on line shapes in spectra of chemically peculiar stars and white dwarfs.

  5. Lifetime broadening of atomic lines produced upon ultrafast dissociation of HCl and HBr

    International Nuclear Information System (INIS)

    Highlights: • Ultrafast dissociation of HCl is triggered by 2p3/2 → σ* excitation. • Ultrafast dissociation of HBr is triggered by 3d5/2 → σ* excitation. • Photoelectron spectroscopy reveals sharp vibrational molecular lines and broad atomic lines. • The profiles of the atomic lines are analyzed in detail. • We extract the lifetime of the inner shell hole in the neutral atomic fragment. - Abstract: Ultrafast dissociation of the HCl and HBr molecules excited respectively to the 2p3/2 → σ* and 3d5/2 → σ* resonances are studied with high resolution photoelectron spectroscopy. Sharp vibrational molecular lines and broad atomic lines are observed. The analysis of the profile of the atomic lines gives access to the lifetimes of the inner shell 2p3/2 hole in the Cl* (2p3/2)−1 3s23p6 configuration, and the inner shell 3d5/2 hole in the Br* (3d5/2)−1 4s24p6 configuration

  6. Pressure broadening and shift of K D1 and D2 lines in the presence of 3He and 21Ne

    Science.gov (United States)

    Li, Rujie; Li, Yang; Jiang, Liwei; Quan, Wei; Ding, Ming; Fang, Jiancheng

    2016-06-01

    Due to the collisions with alkali-metal atoms, the buffer gases used in spin-exchange optical pumping systems induce a broadening of spectral profiles and a shift in the resonance frequency. Here we report the pressure broadening and shift rates of K D 1 and D 2 lines in the presence of 21Ne for the first time and values for 3He have been reinvestigated by means of laser absorption spectroscopy. We have also examined the temperature dependence of these collisional effects in a range of 435-458 K. A comparison for the broadening and shift rates to those of other isotopes, 4He and 20Ne, is presented.

  7. Another way to view the chain conformation broadening of the line-width distribution measured in dynamic light scattering

    Institute of Scientific and Technical Information of China (English)

    吴奇; 牛爱珍

    1999-01-01

    In dynamic laser light scattering (LLS), for a given polydisperse sample, a line-width distribution G(Γ) or the translational diffusion coefficient distribution G(D) can be obtained from the measured time correlation function. For rigid colloid particles, G(Γ) can be directly related to the hydrodynamic size distribution. However, for flexible polymer chains, G(Γ) depends not only on the chain length distribution, but also on the relaxation of the chain conformation; that is, even for a monodisperse polymer sample there still exists a chain conformation distribution. If the time scale of the chain conformation relaxation is comparable to that of the translational diffusion, such as in the case of a very long polymer chain, the conformation relaxation might lead to an additional broadening in G (Γ). This "conformation broadening" has been directly observed for the first time by comparing two G(Γ) s obtained from a poly(N-isopropyl-acrylamide) solution at~25℃ and~32℃ at which the solution is ther

  8. Analysis of line broadening and spectral asymmetry in an all-fiber torsional acousto-optic band-pass filter

    International Nuclear Information System (INIS)

    The transmission properties of an all-fiber torsional acousto-optic (AO) band-pass filter with a sub-nm bandwidth is studied. The device is based on torsional AO coupling in a highly birefringent (HB) optical fiber. The full width at half maximum (FWHM) measured in a conventional band (C-band) is 0.88 nm, which is compared with the theoretical value of 0.45 nm estimated by using the coupled mode theory. The line broadening and the spectral asymmetry observed in experiments are investigated in detail through our theoretical model and full numerical analyses. The influence of the non-uniformity in the birefringence of the HB fiber on the filter's transmission is analyzed quantitatively in terms of the change in the filtering bandwidth, the sidelobe asymmetry, and the resonance shift.

  9. Microscopic Theoretical Calculations ofR-Line Thermal Shifts and Broadenings of MgO:Cr3+

    Institute of Scientific and Technical Information of China (English)

    MA DongPing; LIU YanYun; MA Ning; CHEN JuRong

    2002-01-01

    By taking into account all the irreducible representations and their components in t he electron-phononinteraction (EPI) as well as all the levels and the admixtures of basic wavefunctions within d3 elect ronic configuration,the values of all the parameters in the expressions of thermal shift (TS) and thermal broadening (TB) due to EPI forthe ground level, R level and R line of MgO:Cr3+ have microscopically been evaluated; and then, TS and TB of R lineand various contributions to them have uniformly been calculated. The results arc in very good agreement with theexperimental data. It is found that all the three terms of TS due to EPI are red shifts; the Raman term is the largestone, and the optical-branch term and neighbor-level term are important for TS; the contribution to TS from thermalexpansion is bluc shift, which is also important. The R-line TS of MgO:Cr3+ comes from the first-order term of EPI. Theelastic Raman scattering of acoustic phonons plays a dominant role in R-line TB of MgO:Cr3+. For both TS and TB,it is very important to take into account all the admixtures of basic wavefunctions within d3 electronic configuration.

  10. How two-dimensional brick layer J-aggregates differ from linear ones: excitonic properties and line broadening mechanisms

    CERN Document Server

    Dijkstra, Arend G; Knoester, Jasper; Nelson, Keith A; Cao, Jianshu

    2016-01-01

    We study the excitonic coupling and homogeneous spectral line width of brick layer J-aggregate films. We begin by analysing the structural information revealed by the two-exciton states probed in two-dimensional spectra. Our first main result is that the relation between the excitonic couplings and the spectral shift in a two-dimensional structure is different (larger shift for the same nearest neighbour coupling) from that in a one-dimensional structure, which leads to an estimation of dipolar coupling in two-dimensional lattices. We next investigate the mechanisms of homogeneous broadening - population relaxation and pure dephasing - and evaluate their relative importance in linear and two-dimensional aggregates. Our second main result is that pure dephasing dominates the line width in two-dimensional systems up to a crossover temperature, which explains the linear temperature dependence of the homogeneous line width. This is directly related to the decreased density of states at the band edge when compared...

  11. Modification of the MOOG spectral synthesis codes to account for Zeeman broadening of spectral lines

    CERN Document Server

    Deen, Casey

    2013-01-01

    In an attempt to widen access to the study of magnetic fields in stellar astronomy, I present MOOGStokes, a version of the MOOG one-dimensional LTE radiative transfer code, overhauled to incorporate a Stokes vector treatment of polarized radiation through a magnetic medium. MOOGStokes is a suite of three complementary programs, which together can synthesize the disk-averaged emergent spectrum of a star with a magnetic field. The first element (a pre-processing script called CounterPoint) calculates for a given magnetic field strength, wavelength shifts and polarizations for the components of Zeeman sensitive lines. The second element (a MOOG driver called SynStokes derived from the existing MOOG driver Synth) uses the list of Zeeman shifted absorption lines together with the existing machinery of MOOG to synthesize the emergent spectrum at numerous locations across the stellar disk, accounting for stellar and magnetic field geometry. The third and final element (a post-processing script called DiskoBall) calc...

  12. Stress-strain relationship and XRD line broadening in [0001] textured hexagonal polycrystalline materials

    International Nuclear Information System (INIS)

    Stress analysis with X-ray diffraction (XRD) for hexagonal polycrystalline materials in the Laue classes 6/mmm and 6/m has been studied on the basis of the crystal symmetry of the constituent crystallites which was proposed by R. Yokoyama and J. Harada ['Re-evaluation of formulae for X-ray stress analysis in polycrystalline specimens with fibre texture', Journal of Applied Crystallography, Vol.42, pp.185-191 (2009)]. The relationship between the stress and strain observable by XRD in a hexagonal polycrystalline material with [0001] fibre texture was formulated in terms of the elastic compliance defined for its single crystal. As a result, it was shown that the average strains obtained in the crystallites for both symmetries of 6/mmm and 6/m are different from each other under the triaxial or biaxial stress field. Then, it turned out that the line width of XRD changes depending on the measurement direction. (author)

  13. DETERMINATION OF THE SPONTANEOUS EMISSION PROBABILITIES AND THE COLLISION SELF-BROADENING COEFFICIENTS OF THE СО2 SPECTRAL LINES

    Directory of Open Access Journals (Sweden)

    K. I. Arshinov

    2013-01-01

    Full Text Available The technique of simultaneous determination of the spontaneous emission probabilities Аmn and the collision self-broadening coefficients γmn of the СО2 spectral lines is presented. The dependence of the absorption coefficient on the gas pressure, obtained for the СО210R22 line at temperature 300 K was measured. Using the data, the spontaneous emission probability Аmn and the collision self-broadening coefficient γmn were calculated.

  14. Using the Doppler broadened γ line of the 10B(n,αγ)7Li reaction for thermal neutron detection

    Science.gov (United States)

    Ben-Galim, Y.; Wengrowicz, U.; Moreh, R.; Orion, I.; Raveh, A.

    2016-02-01

    When a thermal neutron is absorbed by 10B in the 10B(n,α)7Li reaction, there is a chance of 94% that a 478 keV photon be emitted by an excited 7Li nucleus. This reaction is exothermic with a Q-value of 2.31 MeV and the nuclei are emitted with kinetic energies of E(α)=1.47 MeV and E(7Li*)=0.84 MeV. This implies that the 478 keV γ line is emitted by a moving 7Li nucleus and hence is expected to be Doppler broadened. In the present work we suggest to use this broadening of the γ line as a fingerprint for the detection of thermal neutrons using a high resolution gamma spectrometer. We thus developed a Monte Carlo program using a MATLAB code based on a High Purity Germanium (HPGe) detector coupled with a Boron Carbide (B4C) sheet to calculate the γ line broadening. Our simulation shows that the FWHM width of the resulting γ line is 12.6 keV, in good agreement with our measurement. Hence the broadened γ line emitted by the 10B(n,αγ)7Li reaction and detected by a HPGe detector shows that this method is an effective tool for neutron detection while maintaining good gamma discrimination.

  15. Temperature dependences of self- and N2-broadened line-shape parameters in the ν3 and ν5 bands of 12CH3D: Measurements and calculations

    Science.gov (United States)

    Predoi-Cross, A.; Malathy Devi, V.; Sutradhar, P.; Sinyakova, T.; Buldyreva, J.; Sung, K.; Smith, M. A. H.; Mantz, A. W.

    2016-07-01

    This paper presents the results of a spectroscopic line shape study of self- and nitrogen-broadened 12CH3D transitions in the ν3 and ν5 bands in the Triad region. We combined five pure gas spectra with eighteen spectra of lean mixtures of 12CH3D and nitrogen, all recorded with a Bruker IFS-125 HR Fourier transform spectrometer. The spectra have been analyzed simultaneously using a multispectrum nonlinear least squares fitting technique. N2-broadened line parameters for 184 transitions in the ν3 band and 205 transitions in the ν5 band were measured. In addition, line positions and line intensities were measured for 168 transitions in the ν3 band and 214 transitions in the ν5 band. We have observed 10 instances of weak line mixing corresponding to K″=3 A1 or A2 transitions. Comparisons were made for the N2-broadening coefficients and associated temperature exponents with corresponding values calculated using a semi-classical Robert Bonamy type formalism that involved an inter-molecular potential with terms corresponding to short- and long-range interactions, and exact classical molecular trajectories. The theoretical N2-broadened coefficients are overestimated for high J values, but are in good agreement with the experimental values for small and middle range J values.

  16. Modeling of x-ray diffraction line broadening with the voigt function: Applications to high-(T[sub c]) superconductors. Doctoral thesis

    Energy Technology Data Exchange (ETDEWEB)

    Balzar, D.

    1993-01-01

    A method to analyze powder-diffraction line broadening is proposed and applied to some novel high-T(c) superconductors. Assuming that both size-broadened and strain-broadened profiles of the pure-specimen profile are described with a Voigt function, it is shown that the analysis of Fourier coefficients leads to the Warren-Averbach method of separation of size and strain contributions. The method was applied to two cubic structures with average volume-weighted domain sizes up to 3600 A, as well as to tetragonal and orthorhombic (La-Sr)2CuOr, which exhibit weak line broadenings and highly overlapping reflections. Comparison with the integral-breadth methods is given. Reliability of the method is discussed in the case of a cluster of the overlapping peaks. The analysis of La2CuO4 and La(1.85)M(0.15)CuO4 (M = Ca, Ba, Sr) high-T(c) superconductors showed that microstrains and incoherently diffracting domain sizes are highly anisotropic. In the superconductors, stacking-fault probability increases with increasing T(c); microstrain decreases. In La2CuO4, different broadening of (h00) and (0k0) reflections is not caused by stacking faults; it might arise from lower crystallographic symmetry.

  17. Method of averaged energy differences of coupled states and other approaches for calculation line broadening parameters of HD16O transitions

    Science.gov (United States)

    Dudaryonok, A. S.; Voronin, B. A.; Lavrentieva, N. N.; Lugovskoy, A. A.; Starikov, V. I.

    2012-11-01

    Air-broadening coefficients of the water isotopologue HD16O up to J = 50 for P, Q and R branches calculated using different methods are presented. For partially labeled lines ("good" quantum numbers: J, symmetry and level number) we combined three methods for calculating half-widths: J-dependence and JJ'-dependence up to J=15 and averaging coefficients calculated using a previously developed semi-empirical method for high J (15-50). For lines with full assignments based on normal modes v1, v2, v3, Ka, Kc we used: (a) an analytical model (approximation) which depends on use of rotational quantum numbers J and Ka for both the upper and lower levels; and (b) a method based on the estimate of the averaged energy differences between coupled states. The comparison of calculated data with broadening coefficients from HITRAN-2008 and available experimental data is presented. The resulting broadening coefficients can be used to calculate spectra of water vapor with hundreds millions of weak lines with reasonable accuracy. The line list VTT [Voronin, Tennyson, Tolchenov, MNRAS, 2010], supporting programs, files for calculations of spectra HD16O and estimation of broadening coefficient are made freely available also in electronic form via http://www.exomol.com.

  18. Line parameters including temperature dependences of self- and air-broadened line shapes of 12C16O2: 1.6-μm region

    Science.gov (United States)

    Devi, V. Malathy; Benner, D. Chris; Sung, Keeyoon; Brown, Linda R.; Crawford, Timothy J.; Miller, Charles E.; Drouin, Brian J.; Payne, Vivienne H.; Yu, Shanshan; Smith, Mary Ann H.; Mantz, Arlan W.; Gamache, Robert R.

    2016-07-01

    Pressure-broadened line shapes in the 30013←00001 (ν1+4 ν20 +ν3) band of 12C16O2 at 6228 cm-1 are reanalyzed using new spectra recorded with sample temperatures down to 170 K. High resolution, high signal-to-noise (S/N) laboratory measurements of line shapes (Lorentz air- and self-broadened half-width coefficients, pressure-shift coefficients and off-diagonal relaxation matrix element coefficients) as a function of gas sample temperatures for various pressures and volume mixing ratios are presented. The spectra were recorded using two different Fourier transform spectrometers (FTS): (1) the McMath-Pierce FTS located at the National Solar Observatory on Kitt Peak, Arizona (and reported in Devi et al., J Mol Spectrosc 2007;245:52-80) and, (2) the Bruker IFS-125HR FTS at the Jet Propulsion Laboratory in Pasadena, California. The 19 spectra taken at Kitt Peak were all recorded near room temperature while the 27 Bruker spectra were acquired both at room temperature and colder temperatures (170-296 K). Various spectral resolutions (0.004-0.011 cm-1), absorption path lengths (2.46-121 m) and CO2 samples (natural and 12C-enriched) were included in the dataset. To maximize the accuracies of the various retrieved line parameters, a multispectrum nonlinear least squares spectrum fitting software program was used to adjust the ro-vibrational constants (G,B,D etc.) and intensity parameters (including Herman-Wallis terms) instead of directly measuring the individual line positions and intensities. To minimize systematic residuals, line mixing (via off-diagonal relaxation matrix elements) and quadratic speed dependence parameters were included in the analysis. Contributions from other weakly absorbing bands: the 30013←00001 and 30012←00001 bands of 13C16O2, the 30013←00001 band of 12C16O18O, hot bands 31113←01101 and 32212←02201 of 12C16O2, as well as the 40013←10001 and the 40014←10002 bands of 12C16O2, present within the fitted interval were also measured

  19. Air- and self-broadened half widths, pressure-induced shifts, and line mixing in the ν2 band of 12CH4

    International Nuclear Information System (INIS)

    Lorentz self- and air-broadened half width and pressure-induced shift coefficients and their dependences on temperature have been measured from laboratory absorption spectra for nearly 130 transitions in the ν2 band of 12CH4. In addition line mixing coefficients (using the relaxation matrix element formalism) for both self- and air-broadening were experimentally determined for the first time for a small number of transitions in this band. Accurate line positions and absolute line intensities were also determined. These parameters were obtained by analyzing high-resolution (∼0.003 to 0.01 cm−1) laboratory spectra of high-purity natural CH4 and air-broadened CH4 recorded at temperatures between 226 and 297 K using the McMath–Pierce Fourier transform spectrometer (FTS) located at the National Solar Observatory on Kitt Peak, Arizona. A multispectrum nonlinear least squares technique was used to fit short (5–15 cm−1) spectral intervals in 24–29 spectra simultaneously. Parameters were determined for ν2 transitions up to J″=16. The variations of the measured broadening and shift parameters with the rotational quantum number index and tetrahedral symmetry species are examined. The present results are also compared with previous measurements available in the literature. -- Highlights: • Self- and air-broadening parameters of the methane ν2 band have been measured. • First determination of temperature dependences of line widths and shifts in this band. • First measurements of line mixing in the ν2 band. • Good agreement with similar parameters from previous studies

  20. Self- and N2-broadening of CH3Br ro-vibrational lines in the ν2 band: The J and K dependence

    Science.gov (United States)

    Boussetta, Z.; Kwabia Tchana, F.; Aroui, H.

    2015-02-01

    Methyl bromide (CH3Br) is the major source of inorganic bromine in the atmosphere and contributes significantly to ozone depletion. Indeed, CH3Br is dissociated by UV radiation, producing Br radicals that catalyze the destruction of ozone. In this paper, we report measured Lorentz self- and N2-broadening coefficients of CH3Br in the ν2 fundamental band using a mono-spectrum non-linear least squares fitting of Voigt profiles which appeared to properly model the observed molecular line shapes within the noise level. These measurements were made by analyzing 12 laboratory absorption spectra recorded at high resolution (0.005, 0.003 or 0.002 cm-1) using the Fourier transform spectrometer Bruker IF125HR located at the LISA facility in Créteil. The spectra were obtained at room temperature using a White-type multipass cell with an optical path of 0.849 m and various pressures. We have been able to determine the self- and N2-broadening coefficients of 948 ν2 transitions with quantum numbers as high as J = 49 and K = 10. The measured self-broadening coefficients range from 0.1542 to 0.4930 cm-1 atm-1 and the N2-broadening coefficients range from 0.0737 to 0.1284 cm-1 atm-1 at 295 K. The accuracy of the broadening coefficients measured in this work is between 4% and 8%, depending on the studied transition. Comparisons with measurements taken in the ν5 and ν6 bands of CH3Br did not show any clear vibrational dependence. The J and K dependences of the self- and N2-broadening coefficients have been observed and the rotational K dependence has been modeled using empirical polynomial expression. On average, the empirical expression reproduce the measured broadening coefficients to within 6%. The data obtained represent a significant contribution to the determination of broadening coefficients of CH3Br useful for atmospheric remote sensing and applications. Note: The assignment column gives the isotopologue (79 for CH379Br and 81 for CH381Br) for which the transition is

  1. Line parameters including temperature dependences of air- and self-broadened line shapes of 12C16O2: 2.06-μm region

    Science.gov (United States)

    Benner, D. Chris; Devi, V. Malathy; Sung, Keeyoon; Brown, Linda R.; Miller, Charles E.; Payne, Vivienne H.; Drouin, Brian J.; Yu, Shanshan; Crawford, Timothy J.; Mantz, Arlan W.; Smith, Mary Ann H.; Gamache, Robert R.

    2016-08-01

    This study reports the results from analyzing a number of high resolution, high signal-to-noise ratio (S/N) spectra in the 2.06-μm spectral region for pure CO2 and mixtures of CO2 in dry air. A multispectrum nonlinear least squares curve fitting technique has been used to retrieve the various spectral line parameters. The dataset includes 27 spectra: ten pure CO2, two 99% 13C-enriched CO2 and fifteen spectra of mixtures of 12C-enriched CO2 in dry air. The spectra were recorded at various gas sample temperatures between 170 and 297 K. The absorption path lengths range from 0.347 to 49 m. The sample pressures for the pure CO2 spectra varied from 1.1 to 594 Torr; for the two 13CO2 spectra the pressures were ∼10 and 146 Torr. For the air-broadened spectra, the pressures of the gas mixtures varied between 200 and 711 Torr with CO2 volume mixing ratios ranging from 0.014% to 0.203%. The multispectrum fitting technique was applied to fit simultaneously all these spectra to retrieve consistent set of line positions, intensities, and line shape parameters including their temperature dependences; for this, the Voigt line shape was modified to include line mixing (via the relaxation matrix formalism) and quadratic speed dependence. The new results are compared to select published values, including recent ab initio calculations. These results are required to retrieve the column averaged dry air mole fraction (XCO2) from space-based observations, such as the Orbiting Carbon Observatory-2 (OCO-2) satellite mission that NASA launched in July 2014.

  2. Modelling dislocation-induced anisotropic line broadening in Rietveld refinements using a Voigt function. II. Application to neutron powder diffraction data

    Energy Technology Data Exchange (ETDEWEB)

    Wu, E.; Gray, E.M.A. [Griffith Univ., Nathan (Australia). Fac. of Sci. and Technol.; Kisi, E.H

    1998-06-01

    For pt.I see ibid., vol.31, p.356-62, 1998. In paper I an approach was developed to the problem of modelling dislocation-induced X-ray or neutron-diffraction-line broadening. This paper applies those findings to the Rietveld refinement of the neutron powder diffraction profiles of deuterium-cycled LaNi{sub 5} and {beta}-PdD{sub 0.66}. These interstitially modified materials exhibit, respectively, strong and weak anisotropic strain broadening. The broadening in LaNi{sub 5} is consistent with a dislocation slip system a/3 left angle anti 2110 right angle {l_brace}0 anti 110{r_brace}, in agreement with transmission electron microscopy studies. In PdD{sub 0.66} the model predicts a regular distribution of screw dislocations, which remains to be confirmed by other techniques. (orig.) 28 refs.

  3. Noble-gas broadening rates for the 6s2S0→6s6p 1,3P1 resonance and intercombination lines of barium

    International Nuclear Information System (INIS)

    The collisional-broadening and -shift rate coefficients (kbr and kshift), for both helium and argon buffer gases, have been measured in the impact limit for the 6s21S0→6s6p 3P1 intercombination transition of barium. Detailed absorption line shapes were measured at three different ground-state number densities by monitoring the transmitted intensity of a weak cw probe laser as it was scanned over the transition. A single, density-independent line shape was then constructed and fit to a sum of Voigt functions (to account for hyperfine structure and isotope shifts) in order to determine the broadening and shift rates. By repeating the process for several buffer-gas pressures, kbr and kshift were determined from least-squares straight-line fits to the broadening and shift rates versus buffer-gas number density. Absolute normalization of the line-shape data was used to provide accurate ground-state column densities. Column-density information was then combined with measurements of white-light-absorption equivalent widths for the 6s21S0→6s6p 1P1 resonance transition to yield broadening rates for that transition. These values for the resonance line lie between previous literature values, which are widely discrepant. Finally we measured the absolute metastable 6s5d 3D2 column density under conditions of optical pumping through the 3P1 level, and determined that, in steady state, even with a weak cw pump laser, ∼20% of all barium atoms in the vapor could be found in the 3D2 level (with approximately 60% spread over the full 3DJ metastable manifold)

  4. Intensities and self-broadening coefficients of the strongest water vapour lines in the 2.7 and 6.25μm absorption bands

    OpenAIRE

    Ptashnik, Igor V.; McPheat, Robert; Polyansky, Oleg L.; Shine, Keith P.; Smith, Kevin M.

    2016-01-01

    Intensities and self-broadening coefficients are presented for about 460 of the strongest water vapour lines in the spectral regions 1400–1840 cm−1 and 3440–3970 cm−1 at room temperature, obtained from rather unique measurements using a 5-mm-path-length cell. The retrieved spectral line parameters are compared with those in the HITRAN database ver. 2008 and 2012 and with recent ab-initio calculations. Both the retrieved intensities and half-widths are on average in reasonable agreement with t...

  5. Alfv\\'en Wave Turbulence as a Coronal Heating Mechanism: Simultaneously Predicting the Heating Rate and the Wave-Induced Emission Line Broadening

    CERN Document Server

    Oran, R; van der Holst, B; Sokolov, I V; Gombosi, T I

    2014-01-01

    In the present work, we test the predictions of the AWSoM model, a global extended-MHD model capable of calculating the propagation and turbulent dissipation of Alfv\\'en waves in any magnetic topology, against high resolution spectra of the quiescent off-disk solar corona. Wave dissipation is the only heating mechanism assumed in this model. Combining 3D model results with the CHIANTI atomic database, we were able to create synthetic line-of-sight spectra which include the effects of emission line broadening due to both thermal and wave-related non-thermal motions. To the best of our knowledge this is the first time a global model is used to obtain synthetic non-thermal line broadening. We obtained a steady-state solution driven by a synoptic magnetogram and compared the synthetic spectra with SUMER observations of a quiescent area above the solar west limb extending between 1.04 and 1.34 solar radii at the equator. Both the predicted line widths and the total line fluxes were consistent with the observations...

  6. Homogeneous and inhomogeneous broadenings and the Voigt line shapes in the phase-resolved and intensity sum-frequency generation vibrational spectroscopy

    Science.gov (United States)

    Chen, Shun-Li; Fu, Li; Gan, Wei; Wang, Hong-Fei

    2016-01-01

    In this report, we show that the ability to measure the sub-1 cm-1 resolution phase-resolved and intensity high-resolution broadband sum frequency generation vibrational spectra of the -CN stretch vibration of the Langmuir-Blodgett (LB) monolayer of the 4-n-octyl-4'-cyanobiphenyl (8CB) on the z-cut α-quartz surface allows the direct comparison and understanding of the homogeneous and inhomogeneous broadenings in the imaginary and intensity SFG vibrational spectral line shapes in detail. The difference of the full width at half maximum (FWHM) of the imaginary and intensity sum-frequency generation vibrational spectroscopy spectra of the same vibrational mode is the signature of the Voigt line shape and it measures the relative contribution to the overall line shape from the homogeneous and inhomogeneous broadenings in SFG vibrational spectra. From the phase-resolved and intensity spectra, we found that the FWHM of the 2238.00 ± 0.02 cm-1 peak in the phase-resolved imaginary and intensity spectra is 19.2 ± 0.2 cm-1 and 21.6 ± 0.4 cm-1, respectively, for the -CN group of the 8CB LB monolayer on the z-cut α-quartz crystal surface. The FWHM width difference of 2.4 cm-1 agrees quantitatively with a Voigt line shape with a homogeneous broadening half width of Γ = 5.29 ± 0.08 cm-1 and an inhomogeneous standard derivation width Δω = 5.42 ± 0.07 cm-1. These results shed new lights on the understanding and interpretation of the line shapes of both the phase-resolved and the intensity SFG vibrational spectra, as well as other incoherent and coherent spectroscopic techniques in general.

  7. Self-, N2-, O2-broadening coefficients and line parameters of HFC-32 for ν7 band and ground state transitions from infrared and microwave spectroscopy

    Science.gov (United States)

    Tasinato, Nicola; Turchetto, Arianna; Puzzarini, Cristina; Stoppa, Paolo; Pietropolli Charmet, Andrea; Giorgianni, Santi

    2014-09-01

    Hydrofluorocarbons have been used as replacement gases of chlorofluorocarbons, since the latter have been phased out by the Montreal Protocol due to their environmental hazardous ozone-depleting effects. This is also the case of difluoromethane (CH2F2, HFC-32), which nowadays is widely used in refrigerant mixtures together with CF3CH3, CF3CH2F, and CF3CHF2. Due to its commercial use, in the last years, the atmospheric concentration of HFC-32 has increased significantly. However, this molecule presents strong absorptions within the 8-12 μm atmospheric window, and hence it is a greenhouse gas which contributes to global warming. Although over the years several experimental and theoretical investigations dealt with the spectroscopic properties of CH2F2, up to now pressure broadening coefficients have never been determined. In the present work, the line-by-line parameters of CH2F2 are retrieved for either ground state or ν7 band transitions by means of microwave (MW) and infrared (IR) absorption spectroscopy, respectively. In particular, laboratory experiments are carried out on 9 pure rotational transitions of the ground state and 26 ro-vibrational transitions belonging to the ν7 band lying around 8.2 μm within the atmospheric region. Measurements are carried out at room temperature on self-perturbed CH2F2 as well as on CH2F2 perturbed by N2 and O2. The line shape analysis leads to the first determination of self-, N2-, O2-, and air-broadening coefficients, and also of line intensities (IR). Upon comparison, broadening coefficients of ground state transitions are larger than those of the ν7 band, and no clear dependence on the rotational quantum numbers can be reported. The obtained results represent basic information for the atmospheric modelling of this compound as well as for remote sensing applications.

  8. Intensities and self-broadening coefficients of the strongest water vapour lines in the 2.7 and 6.25 μm absorption bands

    Science.gov (United States)

    Ptashnik, Igor V.; McPheat, Robert; Polyansky, Oleg L.; Shine, Keith P.; Smith, Kevin M.

    2016-07-01

    Intensities and self-broadening coefficients are presented for about 460 of the strongest water vapour lines in the spectral regions 1400-1840 cm-1 and 3440-3970 cm-1 at room temperature, obtained from rather unique measurements using a 5-mm-path-length cell. The retrieved spectral line parameters are compared with those in the HITRAN database ver. 2008 and 2012 and with recent ab-initio calculations. Both the retrieved intensities and half-widths are on average in reasonable agreement with those in HITRAN-2012. Maximum systematic differences do not exceed 4% for intensities (1600 cm-1 band) and 7% for self-broadening coefficients (3600 cm-1 band). For many lines however significant disagreements were detected with the HITRAN-2012 data, exceeding the average uncertainty of the retrieval. In addition, water vapour line parameters for 5300 cm-1 (1.9 μm) band reported by us in 2005 were also compared with HITRAN-2012, and show average differences of 4-5% for both intensities and half-widths.

  9. Alkaline broadening in Stars

    CERN Document Server

    De Kertanguy, A

    2015-01-01

    Giving new insight for line broadening theory for atoms with more structure than hydrogen in most stars. Using symbolic software to build precise wave functions corrected for ds;dp quantum defects. The profiles obtained with that approach, have peculiar trends, narrower than hydrogen, all quantum defects used are taken from atomic database topbase. Illustration of stronger effects of ions and electrons on the alkaline profiles, than neutral-neutral collision mechanism. Keywords : Stars: fundamental parameters - Atomic processes - Line: profiles.

  10. Broadening and shift of the intercombination spectral line of the second group elements (Hg, Cd and Zn) perturbed by inert gases

    International Nuclear Information System (INIS)

    The Van der Waals and Lennard - Jones potential parameters for the ground and exited states of the second group elements (Hg, Cd and Zn) perturbed by inert gases (Xe, Kr, Ar, Ne and He) have been calculated using coulomb approximation. The basis of the Lindholm -Foley impact theory and the calculated potential parameters are used for calculating the collision broadening and shift coefficients β and δ for the intercombination lines 253.7, 326.1 and 307.6 nm of Hg, Cd and Zn atoms respectively when they are colliding with inert gas atoms . The calculating coefficients of β and δ are compared with their corresponding experimental values, taken from literatures

  11. Stark Broadening and White Dwarfs

    CERN Document Server

    Dimitrijevic, Milan S; Simic, Zoran; Sahal-Brechot, Sylvie

    2012-01-01

    White dwarf and pre-white dwarf atmospheres are one of the best examples for the application of Stark broadening research results in astrophysics, due to plasma conditions very favorable for this line broadening mechanism. For example in hot hydrogen-deficient (pre-) white dwarf stars Teff = 75 000 K - 180 000 K and log g = 5.5-8 [cgs]. Even for much cooler DA and DB white dwarfs with typical effective temperatures of 10 000 K - 20 000 K, Stark broadening is usually the dominant broadening mechanism. In this review, Stark broadening in white dwarf spectra is considered and the attention is drawn to the STARK-B database (http://stark-b.obspm.fr/), containing Stark broadening parameters needed for white dwarf spectra analysis and synthesis, as well as to the new search facilities which will provide the collective effort to develop Virtual Atomic and Molecular Data Center (VAMDC - http://vamdc.org/).

  12. Solid-state proton NMR of paramagnetic metal complexes: DANTE spin echoes for selective excitation in inhomogeneously broadened lines

    Science.gov (United States)

    Carnevale, Diego; Perez Linde, A. J.; Bauer, Gerald; Bodenhausen, Geoffrey

    2013-08-01

    The paramagnetic complex bis(oxazolinylphenyl)amine-Fe(III)Cl2 is investigated by means of solid-state proton NMR at 18.8 T (800 MHz) using magic-angle spinning at 65 kHz. Spin echoes that are excited and refocused by combs of rotor-synchronized pulses in the manner of 'Delays Alternating with Nutation for Tailored Excitation' (DANTE) allow one to characterize different chemical environments that severely overlap in conventional MAS spectra. Such sequences combine two apparently contradictory features: an overall bandwidth exceeding several MHz, and very selective irradiation of a few kHz within inhomogeneously broadened sidebands. The experimental hyperfine interactions correlate well with DFT calculations.

  13. The relaxation matrix for symmetric tops with inversion symmetry. I. Effects of line coupling on self-broadened ν1 and pure rotational bands of NH3.

    Science.gov (United States)

    Ma, Q; Boulet, C

    2016-06-14

    The Robert-Bonamy formalism has been commonly used to calculate half-widths and shifts of spectral lines for decades. This formalism is based on several approximations. Among them, two have not been fully addressed: the isolated line approximation and the neglect of coupling between the translational and internal motions. Recently, we have shown that the isolated line approximation is not necessary in developing semi-classical line shape theories. Based on this progress, we have been able to develop a new formalism that enables not only to reduce uncertainties on calculated half-widths and shifts, but also to model line mixing effects on spectra starting from the knowledge of the intermolecular potential. In our previous studies, the new formalism had been applied to linear and asymmetric-top molecules. In the present study, the method has been extended to symmetric-top molecules with inversion symmetry. As expected, the inversion splitting induces a complete failure of the isolated line approximation. We have calculated the complex relaxation matrices of self-broadened NH3. The half-widths and shifts in the ν1 and the pure rotational bands are reported in the present paper. When compared with measurements, the calculated half-widths match the experimental data very well, since the inapplicable isolated line approximation has been removed. With respect to the shifts, only qualitative results are obtained and discussed. Calculated off-diagonal elements of the relaxation matrix and a comparison with the observed line mixing effects are reported in the companion paper (Paper II). PMID:27306003

  14. Shift measurements of the stark-broadened ionized helium lines at 1640 and 1215 angstrom. Ph.D. Thesis

    Science.gov (United States)

    Vanzandt, J. R.

    1976-01-01

    Time-resolved measurements were made of the shifts of the ionized helium lines at 1,640 A (n = 3 approaches 2) and 1,215 A (n = 4 approaches 2), and of the Stark profile of the 1,215 A wavelength line. An electromagnetic shock tube was used as a light source. The plasma conditions corresponded to electron temperatures of approximately 3.5 eV and electron densities of 0.8 to 1.8 x 10 to the 17th power/cubic cm. The measured shifts fell between two previous estimates of plasma polarization shifts. The measured Stark width of the 1,215 A wavelength line was up to 30% greater than the theoretical width.

  15. On the determination of plasma electron number density from Stark broadened hydrogen Balmer series lines in Laser-Induced Breakdown Spectroscopy experiments

    Energy Technology Data Exchange (ETDEWEB)

    Pardini, L., E-mail: loren.pard@gmail.com [Istituto di Chimica dei Composti Organometallici del CNR, Area della Ricerca del CNR di Pisa, Via G. Moruzzi 1, 56124 Pisa (Italy); Legnaioli, S.; Lorenzetti, G.; Palleschi, V. [Istituto di Chimica dei Composti Organometallici del CNR, Area della Ricerca del CNR di Pisa, Via G. Moruzzi 1, 56124 Pisa (Italy); Gaudiuso, R.; De Giacomo, A. [Dipartimento di Chimica, Università di Bari, Via Orabona 4, 70126 Bari (Italy); Diaz Pace, D.M. [Instituto de Física ‘Arroyo Seco’, Facultad de Ciencias Exactas, Paraje Arroyo Seco, B7000GHG Tandil (Argentina); Anabitarte Garcia, F. [Photonic Engineering Group, Universidad de Cantabria, Edificio I+D+iTelecomunicación, Dpto. TEISA, 39005 Santander (Spain); Holanda Cavalcanti, G. de [Institute of Physics, Universidade Federal Fluminense, UFF, Campus da Praia Vermelha, Av. Gal Milton Tavares de Souza, Gragoatá, 24310 240 Niterói, RJ (Brazil); Parigger, C. [University of Tennessee Space Institute, 411 B. H. Goethert Parkway, Tullahoma, TN 37388-9700 (United States)

    2013-10-01

    In this work, different theories for the determination of the electron density in Laser-Induced Breakdown Spectroscopy (LIBS) utilizing the emission lines belonging to the hydrogen Balmer series have been investigated. The plasmas were generated by a Nd:Yag laser (1064 nm) pulsed irradiation of pure hydrogen gas at a pressure of 2 · 10{sup 4} Pa. H{sub α}, Η{sub β}, Η{sub γ}, Η{sub δ}, and H{sub ε} Balmer lines were recorded at different delay times after the laser pulse. The plasma electron density was evaluated through the measurement of the Stark broadenings and the experimental results were compared with the predictions of three theories (the Standard Theory as developed by Kepple and Griem, the Advanced Generalized Theory by Oks et al., and the method discussed by Gigosos et al.) that are commonly employed for plasma diagnostics and that describe LIBS plasmas at different levels of approximations. A simple formula for pure hydrogen plasma in thermal equilibrium was also proposed to infer plasma electron density using the H{sub α} line. The results obtained showed that at high hydrogen concentration, the H{sub α} line is affected by considerable self-absorption. In this case, it is preferable to use the H{sub β} line for a reliable calculation of the electron density. - Highlights: • We evaluated the electron density in LIPs utilizing the hydrogen Balmer series. • Plasmas were generated by a Nd:Yag laser (1064 nm) on pure hydrogen gas. • We show that at high hydrogen concentration, H{sub b}eta line is preferable than H{sub a}lpha. • We propose a formula to derive the plasma electron density using the H{sub a}lpha line.

  16. Simulation of X-ray diffraction-line broadening due to dislocations in a model composite material

    NARCIS (Netherlands)

    Bor, T.C.; Cleveringa, H.H.M.; Delhez, R.; Giessen, van der E.

    2001-01-01

    X-ray diffraction-line profiles of two-dimensional, plastically deformed model composite materials are calculated and analysed in detail. The composite consists of elastic reinforcements in a crystalline solid and is subjected to macroscopic shear. Slip occurs in the matrix only due to the collectiv

  17. Quasi-bound complexes in collisions of different linear molecules: Classical trajectory study of their manifestations in rotational relaxation and spectral line broadening

    Science.gov (United States)

    Ivanov, Sergey V.

    2016-07-01

    Stable bimolecular complexes (tightly bound dimers) in the gas phase are usually created during third body stabilization of their unstable precursors-quasi-bound complexes (QCs). The latter can arise under the condition that at least one of the colliding partners has an internal degree of freedom. In this article, the principal difference between "orbitings" and QCs is demonstrated in the classical nonreactive scattering picture. Additionally, fractions of QCs in binary collisions of different linear molecules are compared. Also in the article the influence of QCs on rotational R-T relaxation and on vibration-rotational spectral line broadening is discussed. Explicit formulae shedding light on the QCs contribution to the R-T relaxation cross section and the line width and shift are presented. The obtained results emphasize the need for including QCs in every theoretical modeling of spectroscopic manifestation of intermolecular interactions. Besides the topics above, the possible manifestation of non-impact effects in the central regions of spectral lines due to QCs is stated. And finally, special consideration is given to the problem of adequate simulation of QCs formation at different pressures.

  18. XRD line-broadening characteristics of M-oxides (M = Mg, Mg-Al, Y, Fe) nanoparticles produced by coprecipitation method

    Science.gov (United States)

    Pratapa, S.; Susanti, L.; Insany, Y. A. S.; Alfiati, Z.; Hartono, B.; Mashuri, Taufiq, Ahmad; Fuad, Abdullah; Triwikantoro, Baqiya, M. A.; Purwaningsih, S.; Yahya, E.; Darminto

    2010-10-01

    Simple coprecipitation method has been used to produce nanoparticles of MgO (magnesia), MgOṡAl2O3 (spinel), Y2O3 (yttria) and Fe3O4 (ferrite). The raw materials were, in respective, magnesium powder, magnesium and aluminium powders, ytrria powder, and natural sand. The coprecipitation included the use of suitable acid and base to dissolve the powders or sand and to produce precipitates, as well as the use of water to wash and purify the precipitates, and drying at relatively low temperatures, namely lower than 100° C, followed by heating at 450° C, 750° C, 600° C and 200° C to produce magnesia, spinel, yttria and ferrite nanopowders, respectively. X-ray diffractometry was used to characterise the purity and nanocrystallinity of the final powders. It was found qualitatively that the powders were of high purity. Further line-broadening analysis using single-line and Rietveld-based softwares was performed to reveal the nanocrystallinity of the powders. Different line breadth values were found for the powders, indicating different crystallite sizes. It was also found that, particularly for spinel and yttria, the diffraction peaks exhibited `longer' tails, indicating broader crystallite size distribution. The average crystallite size for the powders ranged from 3 to 70 nm. The results could then be used as `fingerprints' for nanocrystallinity using x-ray diffractometry. The XRD crystallite sizes for yttria and ferrite nanocrystals are in fair agreement with their counterparts from electron microscopy observation.

  19. Line broadening and crystallographic sites for Eu{sup 3+} in disordered double borate Ca{sub 3}Gd{sub 2}(BO{sub 3}){sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Hyo Jin, E-mail: hjseo@pknu.ac.kr

    2014-08-01

    Highlights: • The line broadening properties of Ca{sub 3}Gd{sub 2}(BO{sub 3}){sub 4}: Eu{sup 3+} are investigated. • Three types of substitution sites for Eu{sup 3+} are identified in Ca{sub 3}Gd{sub 2}(BO{sub 3}){sub 4}. • The crystal-field parameters are calculated from the {sup 7}F{sub J} levels. • The larger distribution of M-O distances gives higher crystal-field strength on Eu{sup 3+}. - Abstract: The samples of Eu{sup 3+}-doped Ca{sub 3}Gd{sub 2}(BO{sub 3}){sub 4} were synthesized by solid-state reaction. Line broadening and site-substitution properties of Eu{sup 3+} in Ca{sub 3}Gd{sub 2}(BO{sub 3}){sub 4} are investigated by the site-selective laser-excitation spectroscopy. Three excitation lines corresponding to the three crystallographic sites are observed in the excitation spectra of the {sup 7}F{sub 0} → {sup 5}D{sub 0} transition. The spectral lines in the excitation and emission spectra of Ca{sub 3}Gd{sub 2}(BO{sub 3}){sub 4}:Eu{sup 3+} are much broader than those in usual crystalline lattices which are attributable to the structural disorder of the Ca{sub 3}Gd{sub 2}(BO{sub 3}){sub 4} lattice. Crystal-field splittings of three types of Eu{sup 3+} in Ca{sub 3}Gd{sub 2}(BO{sub 3}){sub 4} are determined from selectively excited emission spectra. The crystal-field parameters and crystal-field strength parameters are calculated with the values of experimentally obtained {sup 5}D{sub 0} and {sup 7}F{sub J} energy levels. The results are discussed in relation with the distribution of the substitution sites for Eu{sup 3+} in Ca{sub 3}Gd{sub 2}(BO{sub 3}){sub 4}.

  20. Statistical removal of background signals from high-throughput 1H NMR line-broadening ligand-affinity screens

    International Nuclear Information System (INIS)

    NMR ligand-affinity screens are vital to drug discovery, are routinely used to screen fragment-based libraries, and used to verify chemical leads from high-throughput assays and virtual screens. NMR ligand-affinity screens are also a highly informative first step towards identifying functional epitopes of unknown proteins, as well as elucidating the biochemical functions of protein–ligand interaction at their binding interfaces. While simple one-dimensional 1H NMR experiments are capable of indicating binding through a change in ligand line shape, they are plagued by broad, ill-defined background signals from protein 1H resonances. We present an uncomplicated method for subtraction of protein background in high-throughput ligand-based affinity screens, and show that its performance is maximized when phase-scatter correction is applied prior to subtraction

  1. Statistical removal of background signals from high-throughput {sup 1}H NMR line-broadening ligand-affinity screens

    Energy Technology Data Exchange (ETDEWEB)

    Worley, Bradley; Sisco, Nicholas J.; Powers, Robert, E-mail: rpowers3@unl.edu [University of Nebraska-Lincoln, Department of Chemistry (United States)

    2015-09-15

    NMR ligand-affinity screens are vital to drug discovery, are routinely used to screen fragment-based libraries, and used to verify chemical leads from high-throughput assays and virtual screens. NMR ligand-affinity screens are also a highly informative first step towards identifying functional epitopes of unknown proteins, as well as elucidating the biochemical functions of protein–ligand interaction at their binding interfaces. While simple one-dimensional {sup 1}H NMR experiments are capable of indicating binding through a change in ligand line shape, they are plagued by broad, ill-defined background signals from protein {sup 1}H resonances. We present an uncomplicated method for subtraction of protein background in high-throughput ligand-based affinity screens, and show that its performance is maximized when phase-scatter correction is applied prior to subtraction.

  2. H2, He, and CO2 line-broadening coefficients, pressure shifts and temperature-dependence exponents for the HITRAN database. Part 1: SO2, NH3, HF, HCl, OCS and C2H2

    Science.gov (United States)

    Wilzewski, Jonas S.; Gordon, Iouli E.; Kochanov, Roman V.; Hill, Christian; Rothman, Laurence S.

    2016-01-01

    To increase the potential for use of the HITRAN database in astronomy, experimental and theoretical line-broadening coefficients, line shifts and temperature-dependence exponents of molecules of planetary interest broadened by H2, He, and CO2 have been assembled from available peer-reviewed sources. The collected data were used to create semi-empirical models so that every HITRAN line of the studied molecules has corresponding parameters. Since H2 and He are major constituents in the atmospheres of gas giants, and CO2 predominates in atmospheres of some rocky planets with volcanic activity, these spectroscopic data are important for remote sensing studies of planetary atmospheres. In this paper we make the first step in assembling complete sets of these parameters, thereby creating datasets for SO2, NH3, HF, HCl, OCS and C2H2.

  3. Interpretation of magnetization transfer from inhomogeneously broadened lines (ihMT) in tissues as a dipolar order effect within motion restricted molecules

    Science.gov (United States)

    Varma, G.; Girard, O. M.; Prevost, V. H.; Grant, A. K.; Duhamel, G.; Alsop, D. C.

    2015-11-01

    Comparison of off-resonance saturation with single and dual frequency irradiation indicates a contribution of inhomogeneously broadened lines to magnetization transfer in tissues. This inhomogeneous magnetization transfer (ihMT) phenomenon can be exploited to produce images that highlight tissues containing myelin, in vivo. Here, a model for ihMT is described that includes dipolar order effects from magnetization associated with motion-restricted macromolecules. In this model, equal irradiation at positive and negative frequency offsets eliminates dipolar order and achieves greater saturation than irradiation at a single offset frequency using the same power. Fitting of mouse and human volunteer brain data at different irradiation powers and offset frequencies was performed to assess the relevance of the model and approximate tissue parameters. A key parameter in determining ihMT signal was found to be the relaxation time T1D associated with the dipolar order reservoir and the fraction f of the semi-solid, bound magnetization that possessed a nonzero T1D. Indeed, better fits of myelinated tissue were achieved when assuming f ≠ 1. From such fits, estimated T1Ds of mice in the white matter, (34 ± 14)ms, were much longer than in muscle, T1D = (1 ± 1)ms and the average f from white matter volunteer data was 2.2 times greater than that in grey matter. The combination of f and longer T1Ds was primarily responsible for the much higher ihMT in myelinated tissues, and provided explanation for the species variation. This dipolar order ihMT model should help guide future research, pulse sequence optimization, and clinical applications.

  4. Anomalous broadening of the Moessbauer spectrum lines of oxygen-depleted HTSC ceramic YBa2(Cu(1-x)Fe(x))3O(y) in the structural transition region

    Energy Technology Data Exchange (ETDEWEB)

    Chuev, M.A.; Cherepanov, V.M.; Iakimov, S.S.; Tsymbal, E.IU.; Bush, A.A.; Sauer, CH.; Zinn, W. (Inst. Atomnoi Energii, Moscow (Russian Federation) Inst. Radiotekhniki, Elektroniki i Avtomatiki, Moscow (Russian Federation) Forschungszentrum Juelich GmbH (Germany))

    1992-07-01

    A sharp peak in the temperature dependence of the width of the Moessbauer spectrum lines of Fe-57 nuclei has been detected in the superconducting ceramic YBa2(Cu(0.983)Fe(0.017))3O(6.8) at around 110 K. In view of the Lorentz nature of the observed line broadening, it is suggested that the characteristic charge fluctuation frequency of the nearest oxygen neighbors of the Fe impurity atoms in Cu(1) positions corresponds to the Moessbauer time window (10 exp 7 - 10 exp 9/s) in the temperature range 140-90 K. 7 refs.

  5. Quantum Cascade Laser Measurements of Line Intensities, N2-, O2- and Ar- Collisional Broadening Coefficients of N2O in the  3 Band Near 4.5  m

    KAUST Repository

    Es-sebbar, E.-t.

    2016-04-19

    This study deals with precise measurements of absolute line intensities, N2-, O2- and Ar- collisional broadening coefficients of N2O in the P-branch of the ν3 vibrational band near 4.5 μm. Collisional broadening coefficients of N2O-air are derived from the N2- and O2- broadening contributions by considering an ideal atmospheric composition. Studies are performed at room temperature for 10 rotational transitions over 2190-2202 cm-1 spectral range using a distributed-feedback quantum cascade laser. To retrieve spectroscopic parameters for each individual transition, measured absorption line shape is simulated within Voigt and Galatry profiles. The obtained results compare well with previous experimental data available in the literature: the discrepancies being less than 4% for most of the probed transitions. The spectroscopic data reported here are very useful for the design of sensors used to monitor the abundance of N2O in earth\\'s atmosphere. © The Author(s) 2016.

  6. Homogeneous and inhomogeneous broadenings and the Voigt line shapes in the phase-resolved and intensity sum-frequency generation vibrational spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shunli; Fu, Li; Gan, Wei; Wang, Hongfei

    2016-01-21

    In this report we show that the ability to measure the sub-1 cm-1 resolution phase-resolved and intensity high-resolution broadband sum frequency generation vibrational spectra (HR-BB-SFG-VS) of the –CN stretch vibration of the Langmuir-Blodgett (LB) monolayer of the 4-n-octyl-4’-cyanobiphenyl (8CB) on the z-cut α-quartz surface allows for the first time the direct comparison and understanding of the homogeneous and inhomogeneous broadenings in the imaginary and intensity SFG vibrational spectral lineshapes in detail. The difference of the full width at half maxima (FWHM) of the imaginary and intensity SFG-VS spectra of the same vibrational mode is the signature of the Voigt lineshape and it measures the relative contribution to the overall lineshape from the homogeneous and inhomogeneous broadenings in SFG vibrational spectra. From the phase-resolved and intensity spectra, we found that the FWHM of the 2238.00 ±0.02 cm-1 peak in the phase-resolved imaginary and intensity spectra is 19.2 ± 0.2 cm-1 and 21.6 ± 0.4 cm-1, respectively, for the –CN group of the 8CB LB monolayer on the z-cut α-quartz crystal surface. The FWHM width difference of 2.4 cm-1 agrees quantitatively with a Voigt lineshape with a homogeneous broadening half width of Γ = 5.29 ± 0.08 cm-1 and a inhomogeneous standard derivation width Δω = 5.42 ± 0.07 cm-1. These results shed new lights on the understanding and interpretation of the lineshapes of both the phase-resolved and the intensity SFG vibrational spectra, as well as other incoherent and coherent spectroscopic techniques in general.

  7. Broaden Students' Music Preferences.

    Science.gov (United States)

    Le Blanc, Albert

    1983-01-01

    A model of music preference theory suggests ways that teachers can broaden their students' musical preferences. Teachers can change preferences by changing something in the listener, the social environment, the music, or the ways that the listener processes information. (AM)

  8. Speed-Dependent Broadening and Line-Mixing in CH_4 Perturbed by Air Near 1.64 μm for the French/german Climate Mission MERLIN

    Science.gov (United States)

    Delahaye, Thibault; Tran, Thi Ngoc Ha; Reed, Zachary; Maxwell, Stephen E.; Hodges, Joseph

    2015-06-01

    Climate change is one of the greatest challenges presently facing mankind, and methane is one of the most powerful anthropogenic greenhouse gases. For a better understanding of future climate trends, a satellite dedicated to the measurements of atmospheric methane is under joint development by the French and German space research centers (CNES and DLR). The so-called MERLIN mission (Methane Remote Sensing Lidar Mission, 2019) aims at providing global information on atmospheric methane concentration with a relative uncertainty less than 2% and with a spatial resolution of 50 km Such spectroscopic monitoring of gases in the atmosphere of the Earth, requires a precise description of absorption lines shapes that goes beyond the usual Voigt profile (VP). In the case of methane, the differences between the measured profiles and those given by the VP can be very important, making the VP completely incompatible with the reliable detection of sources and sinks from space. In this work, we present the first results on the modeling of methane lines broadened by air in the 1.64 μm region and the associated spectroscopic parameters, taking into account various collisional effects between molecules that are neglected by the VP: collisional interference between the lines (line-mixing), collision-induced velocity changes (Dicke narrowing effect) and speed dependence of the collisional broadening and shifting. These results were obtained by simultaneously fitting the model parameters to high sensitivity and high-resolution cavity ring-down spectroscopy (CRDS) spectra recorded at the National Institute of Standards and Technology (NIST) over a wide pressure range (5 to 100 kPa). These spectroscopic data and the associated model to calculate the spectrum absorption coefficient will be then used to analyze ground-based atmospheric spectra at the TCCON facility in Park Falls, Wisconsin. C. Kiemle, M. Quatrevalet, G. Ehret et al., Atmos. Meas. Tech. 4 (2011) H. Tran, J.-M. Hartmann, G

  9. The Relaxation Matrix for Symmetric Tops with Inversion Symmetry. I. Effects of Line Coupling on Self-Broadened v (sub 1) and Pure Rotational Bands of NH3

    Science.gov (United States)

    Ma, Q.; Boulet, C.

    2016-01-01

    The Robert-Bonamy formalism has been commonly used to calculate half-widths and shifts of spectral lines for decades. This formalism is based on several approximations. Among them, two have not been fully addressed: the isolated line approximation and the neglect of coupling between the translational and internal motions. Recently, we have shown that the isolated line approximation is not necessary in developing semi-classical line shape theories. Based on this progress, we have been able to develop a new formalism that enables not only to reduce uncertainties on calculated half-widths and shifts, but also to model line mixing effects on spectra starting from the knowledge of the intermolecular potential. In our previous studies, the new formalism had been applied to linear and asymmetric-top molecules. In the present study, the method has been extended to symmetric-top molecules with inversion symmetry. As expected, the inversion splitting induces a complete failure of the isolated line approximation. We have calculated the complex relaxation matrices of selfbroadened NH3. The half-widths and shifts in the ?1 and the pure rotational bands are reported in the present paper. When compared with measurements, the calculated half-widths match the experimental data very well, since the inapplicable isolated line approximation has been removed. With respect to the shifts, only qualitative results are obtained and discussed. Calculated off-diagonal elements of the relaxation matrix and a comparison with the observed line mixing effects are reported in the companion paper (Paper II).

  10. Comparison of trajectory models in calculations of N2-broadened half-widths and N2-induced line shifts for the rotational band of H216O and comparison with measurements

    International Nuclear Information System (INIS)

    In this work, Complex Robert-Bonamy calculations of half-widths and line shifts were done for N2-broadening of water for 1639 transitions in the rotational band using two models for the trajectories. The first is a model correct to second order in time, the Robert-Bonamy parabolic approximation. The second is the solution of Hamilton's equations. Both models use the isotropic part of the atom-atom potential to determine the trajectories. The present calculations used an intermolecular potential expanded to 20th order to assure the convergence of the half-widths and line shifts. The aim of the study is to assess if the difference in the half-widths and line shifts determined from the two trajectory models is greater than the accuracy requirements of the spectroscopic and remote sensing communities. The results of the calculations are compared with measurements of the half-widths and line shifts. It is shown that the effects of the trajectory model greatly exceed the needs of current remote sensing measurements and that line shape parameters calculated using trajectories determined by solving Hamilton's equations agree better with measurement.

  11. Level Width Broaden Effect

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jing-Shang

    2004-01-01

    In fitting the double-differential measurements thelevelwidth broadening effect should be taken into account properly due to Heisenberg uncertainty.Besides level width broadening effect the energy resolution in the measurements is also needed in this procedure.In general,the traditional normal Gaussian expansion is employed.However,the research indicates that to do so in this way the energy balance could not hold.For this reason,the deformed Gaussian expansion functions with exponential form for both the single energy point and continuous spectrum are introduced,with which the normalization and energy balance conditions could hold exactly in the analytical form.

  12. Spectral shapes of Ar-broadened HCl lines in the fundamental band by classical molecular dynamics simulations and comparison with experiments

    Energy Technology Data Exchange (ETDEWEB)

    Tran, H., E-mail: ha.tran@lisa.u-pec.fr [Laboratoire Interuniversitaire des Systèmes Atmosphériques, UMR CNRS 7583, Université Paris Est Créteil, Université Paris Diderot, Institut Pierre-Simon Laplace, 94010 Créteil Cedex (France); Domenech, J.-L. [Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Cientificas, (IEM-CSIC), Serrano 123, 28006 Madrid (Spain)

    2014-08-14

    Spectral shapes of isolated lines of HCl perturbed by Ar are investigated for the first time using classical molecular dynamics simulations (CMDS). Using reliable intermolecular potentials taken from the literature, these CMDS provide the time evolution of the auto-correlation function of the dipole moment, whose Fourier-Laplace transform leads to the absorption spectrum. In order to test these calculations, room temperature spectra of various lines in the fundamental band of HCl diluted in Ar are measured, in a large pressure range, with a difference-frequency laser spectrometer. Comparisons between measured and calculated spectra show that the CMDS are able to predict the large Dicke narrowing effect on the shape of HCl lines and to satisfactorily reproduce the shapes of HCl spectra at different pressures and for various rotational quantum numbers.

  13. Autocorrelation interferometer of constant phase. New method of measurement of homogeneous line width of irradiation under conditions of predominant heterogeneous broadening

    CERN Document Server

    Lebedev, M V

    2001-01-01

    The method for measuring the line homogeneous width without application of the nonlinear-optical effects is proposed in this work. The method is based on applying the new interferometer scheme with a diffraction lattice. The diffraction lattices are successfully used in the interferometry for separating the beams and additional radiation monochromatization. The lattice in the proposed scheme makes it possible to obtain the independence of the phases difference between the interference beams on the wavelength. The interferometer optical scheme is shown

  14. Broadening the radiography spectrum

    International Nuclear Information System (INIS)

    The text discuses the mammography in breast screening and evaluation of breast cancer; Small parts ultrasounds at plaza imaging solutions; role of a Radiographer in mammography-new perspective; Medical imaging education in africa; Caring for the paediatric patient as to broaden radiotherapy spectrum; Problems and challenges in care for children undergoing radiotherapy; Paediatric radiotherapy, management and side effects; The principles of pattern recognition of skeletal structures; the place of distance learning education in broadening the radiography spectrum; the curriculum and budgeting image; sonographer's guide; Computed radiography- X-Ray with vision; digital Radiography in Kenya today; Particle Therapy at Ithemba Labs; The role of lung perfusion and ventilation study in the evaluation of the pulmonary embolism and lastly, an overview of Head and neck treatment at Kenyatta National hospital radiotherapy

  15. Correction method for Doppler broadened {gamma}-ray lines using the linear momentum of the evaporated charged particles in heavy-ion induced fusion-evaporation reactions

    Energy Technology Data Exchange (ETDEWEB)

    Aieche, M. E-mail: aiche@cenbg.in2p3.fr; Aleonard, M.M.; Barreau, G.; Boivin, D.; Bourgine, F.; Cabaussel, D.; Chemin, J.F.; Harston, M.; Scheurer, J.N.; La Rana, G.; Moro, R.; Brondi, A.; Vardaci, E.; Curien, D.; Hannachi, F

    2003-08-11

    A method based on the conservation of linear momentum is used to correct the position and the width of the {gamma}-ray lines of the residual nucleus produced in heavy-ion induced fusion-evaporation reactions. This method implies the measurement of the total number of the emitted particles, their masses, energies and directions of emission in coincidence with the prompt {gamma}-rays. It has been applied to the 120 MeV {sup 32}S+{sup 58}Ni reaction whose data have been collected using the high efficiency and large granularity 4{pi} light charged particle detector DIAMANT, coupled to the 4{pi} {gamma}-ray spectrometer EUROGAM II.

  16. The STARK-B database VAMDC node: a repository for spectral line broadening and shifts due to collisions with charged particles

    Science.gov (United States)

    Sahal-Bréchot, S.; Dimitrijević, M. S.; Moreau, N.; Ben Nessib, N.

    2015-05-01

    Accurate spectroscopic diagnostics and modeling require the knowledge of numerous collisional line profiles. Access to such data via an online database has become indispensable. The STARK-B database is aimed at meeting these needs for widths and shifts of isolated lines of neutral and ionized elements due to electron and ion impacts. This database of the Paris Observatory is a result of scientific cooperation between S Sahal-Bréchot (LERMA) and M S Dimitrijević (AOB). Access to it is free, and it was opened online at the end of 2008. STARK-B is a node of the Virtual Atomic and Molecular Data Centre (VAMDC) and thus complies with VAMDC and Virtual Observatory standards. VAMDC is a European Union-funded collaboration among groups involved in the generation and use of interoperable atomic and molecular data. STARK-B now contains all our semiclassical-perturbation (SCP) calculated data for more than 123 neutral or ionized elements as published in international refereed journals. It is devoted to modeling and spectroscopic diagnostics of stellar atmospheres and envelopes, laboratory plasmas, laser equipment, and technological plasmas. Hence, the range of temperatures and densities covered by the tables is broad and depends on the ionization degree of the radiating atom. The modified semiempirical (MSE) results of calculations have begun to be implemented. In this paper, we highlight the key points of the method and the assumptions used in the calculations, which have lately been revisited. Then we present the database and its recent developments, as well as our ongoing work and our plans for the future.

  17. Experimental study of population inversion and spectral line broadening in a plasma containing a mixture of high Z and low Z ions

    International Nuclear Information System (INIS)

    In our work this past year at the University of Rochester's Laboratory for Laser Energetics we have studied laser-produced plasmas using spherical targets continuing layers of high Z and low Z materials. Our emphasis was on quantitative spectroscopy of ions in a very dense, recombining plasma. The targets used consisted of carbon-copper, carbon-gold, and aluminum-gold mixtures, instead of the originally proposed Fe or Mo mixtures with carbon. The thickness of the Cu and the Au layers were varied in order to study the effect of higher Z ions cooling the plasma. Indeed a pronounced cooling effect was observed by increasing the thickness of the Au layer in targets with Al-Au layers. Electron temperatures were studied by measuring the 1s-2p/1s2-1s2p line ratio of Al XIII to Al XII. Our experimental measurements, together with a collisional-radiative model and a 1-D hydrodynamic code, indicate that the electron temperature falls from 1500 eV with no gold to 950 eV with a 500 angstrom layer of gold. A detailed discussion of our results with Al-Au targets can be found in the enclosed preprint entitled Radiation Cooling in Laser-Produced Plasmas Due to High-Z Layers

  18. Measurement of the Temperature Dependence of Line Mixing and Pressure Broadening Parameters between 296 and 90 K in the v3 band of 12CH4 and their Influence on Atmospheric Methane Retrievals

    Science.gov (United States)

    Mondelain, Didier; Payan, Sebastien; Deng, Wenping; Camy-Peyret, Claude; Hurtmans, Daniel; Mantz, Arlan W.

    2007-01-01

    We measured the temperature dependence of the nitrogen broadening, narrowing and line-mixing coefficients of four lines of the P9 manifold in the v3 band of 12CH4 for atmospheric purposes. The data were collected using our tunable diode laser (TDL) spectrometer with active wavenumber control coupled to a newly developed cold Herriott cell with a path length of 5.37 m and a temperature uniformity of better than 0.01 K along the cell. We recorded and analyzed spectra recorded at sample temperature between 90 K and room temperature. We have investigate the influence of our new results in the inversion model used to retrieve methane profiles from atmospheric spectra; our new results make it possible to retrieve significantly more precise methane profiles. The atmospheric spectra we utilized were obtained by several of us with a balloon-born Fourier Transform infrared experiment in a limb configuration. Differences up to 7% on the retrieved volume mixing ratio were found compared to an inversion model using only HITRAN04 spectroscopic parameters.

  19. Is macroturbulent broadening in OB Supergiants related to pulsations?

    CERN Document Server

    Simón-Díaz, S; Herrero, A; Castro, N; Puls, J; Aerts, C

    2010-01-01

    The spectrum of O and B Supergiants is known to be affected by an important extra line-broadening (usually called \\macro) that adds to stellar rotation. Recent analysis of high resolution spectra has shown that the interpretation of this line-broadening as a consequence of large-scale turbulent motions would imply highly super-sonic velocity fields, making this scenario quite improbable. Stellar oscillations have been proposed as a likely alternative explanation. We present first encouraging results of an observational project aimed at investigating the $macroturbulent$ broadening in O and B Supergiants, and its possible connection with spectroscopic variability phenomena and stellar oscillations: a) all the studied B Supergiants show line profile variations, quantified by means of the first () and third velocity () moments of the lines, b) there is a strong correlation between the peak-to-peak amplitudes of the and variability and the size of the extra-broadening.

  20. Power broadening and collision broadening of gas laser transitions

    NARCIS (Netherlands)

    Bolwijn, P.T.; Alkemade, C.T.J.

    1967-01-01

    From measured tuning characteristics of the amplitude of laser power modulation in single-mode operation, power broadening as well as collision broadening of the laser transition is shown to be relatively important and can be studied separately. It is also found that the d.c. laser power is proporti

  1. Broadening nanotechnology's impact on development

    Science.gov (United States)

    Beumer, Koen

    2016-05-01

    Discussions about nanotechnology and development focus on applications that directly address the needs of the world's poor. Nanotechnology can certainly make an impact in the fight against global poverty, but we need to broaden our imagination.

  2. Coherent Forward Broadening in Cold Atom Clouds

    CERN Document Server

    Sutherland, R T

    2015-01-01

    It is shown that homogeneous line-broadening in a diffuse cold atom cloud is proportional to the resonant optical depth of the cloud. Further, it is demonstrated how the strong directionality of the coherent interactions causes the cloud's spectra to depend strongly on its shape, even when the cloud is held at constant densities. These two numerical observations can be predicted analytically by extending the single photon wave-function model. Lastly, elongating a cloud along the line of laser propagation causes the excitation probability distribution to deviate from the exponential decay predicted by the Beer-Lambert law to the extent where the atoms in the back of the cloud are more excited than the atoms in the front. These calculations are conducted at low densities relevant to recent experiments.

  3. Effect of Pressure Broadening on Molecular Absorption Cross Sections in Exoplanetary Atmospheres

    CERN Document Server

    Hedges, Christina

    2016-01-01

    Spectroscopic observations of exoplanets are leading to unprecedented constraints on their atmospheric compositions. However, molecular abundances derived from spectra are degenerate with the absorption cross sections which form critical input data in atmospheric models. Therefore, it is important to quantify the uncertainties in molecular cross sections to reliably estimate the uncertainties in derived molecular abundances. However, converting line lists into cross sections via line broadening involves a series of prescriptions for which the uncertainties are not well understood. We investigate and quantify the effects of various factors involved in line broadening in exoplanetary atmospheres - the profile evaluation width, pressure versus thermal broadening, broadening agent, spectral resolution, and completeness of broadening parameters - on molecular absorption cross sections. We use H$_2$O as a case study as it has the most complete absorption line data. For low resolution spectra (R$\\lesssim$100) for re...

  4. Understanding Doppler Broadening of Gamma Rays

    Energy Technology Data Exchange (ETDEWEB)

    Rawool-Sullivan, Mohini [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sullivan, John P. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-07-03

    Doppler-broadened gamma ray peaks are observed routinely in the collection and analysis of gamma-ray spectra. If not recognized and understood, the appearance of Doppler broadening can complicate the interpretation of a spectrum and the correct identification of the gamma ray-emitting material. We have conducted a study using a simulation code to demonstrate how Doppler broadening arises and provide a real-world example in which Doppler broadening is found. This report describes that study and its results.

  5. 锶原子窄线宽互组跃迁荧光谱获得及谱线增宽因素分析%Realization of Narrow Linewidth Fluorescence Spectrum of Strontium Intercombination Transition and Analysis of Its Line Broadening Factors

    Institute of Scientific and Technical Information of China (English)

    刘辉; 任洁; 田晓; 常宏

    2013-01-01

    The strontium (5s2)1S0-(5s5p)3P1 intercombination transition is characterized far narrower natural line width than its counterpart dipode transition line (5s2)1S0-(5s5p)3P1 and has been applied in the field of optical frequency standards.In order to obtain its high quality spectrum,the line broadening factors of strontium (5s2)1S0(5s5p)3 P1 intercombination transition fluorescence spectrum are theoretically analyzed based on thermal atomic beam collimated by capillary tubes.The factors,including Doppler effect,laser line width,saturation broadening and transit-time broadening,are considered.Experimentally,the fluorescence spectrum including the saturated fluorescence spectrum,is obtained from the differently collimated strontium thermal atomic beams.The exprimental results show that the higher collimated thermal beam's fluorescence spectrum line width is only 6.5 MHz,which is on the same order of magnitude as the Lamb-dip line width in the saturated fluorescence spectrum (1.7 MHz),and greatly reduces first-order Doppler broadening of spectra.And an external cavity diode laser is locked to the narrow line fluorescence spectrum by modulating the laser's frequency directly,achieving a laser line width of about 0.72 MHz.%锶原子(5s2)1S0-(5s5p)3P1互组跃迁自然线宽远窄于其单态间的(5s2)1S0-(5s5p)1P1偶极跃迁,在光频标中有着实际的应用.为获得该跃迁线的高质量光谱,从理论上分析了利用毛细管准直的热原子束中,锶原子(5s2)1S0-(5s5p)3P1互组跃迁荧光光谱的谱线增宽因素,包括多普勒增宽、激光线宽、饱和增宽和渡越增宽.利用不同准直度的原子束实验获得了该互组跃迁的荧光谱和饱和荧光谱,较高准直的原子束获得荧光谱线宽仅为6.5 MHz,与饱和荧光谱的兰姆凹陷线宽(1.7 MHz)在同一个数量级上,大大减小了谱线的一阶多普勒增宽.通过对频率直接调制将激光器锁定在该谱线上,锁定后激光的线宽约为0.72 MHz.

  6. Temperature Dependence of Stark Broadening Dominated by Strong Collisions

    International Nuclear Information System (INIS)

    The influence of electron temperature in the broadening of spectral lines dominated by strong collisions has been studied. Computer simulation allows us to study the effects of strong and weak collisions separately. Results shown here are focused on some Sr+ and Ba+ resonance lines as examples of lines broadened dominantly by strong collisions. The exact numerical integration of the perturbation process due to the collision with a single particle permits the evaluation of Weisskopf radius. This parameter is usually defined as rw ∼ 1/v ∼ 1/√T, obtained from Bora approximation that is correct for high temperatures. However, at low temperatures the full integration of the collision process permits to test the relationship rw ∼ 1/T1/6. This calculation has allowed us to study the influence of temperature on the broadening of the lines dominated by strong collisions. This study has been done in two ways : through a plasma simulation and analyzing the calculated Weisskopf radius for an individual collision. The obtained results show that at low temperatures the width of the line increases for increasing temperature as a consequence of an increase of the number of collisions not compensated by the decrease of Weisskopf radius

  7. Spectrally selective optical pumping in Doppler-broadened cesium atoms

    International Nuclear Information System (INIS)

    The D1 line spectrally selective pumping process in Doppler-broadened cesium is analyzed by solving the optical Bloch equations. The process, described by a three-level model with the Λ scheme, shows that the saturation intensity of broadened atoms is three orders of magnitude larger than that of resting atoms. The |Fg = 3> → |Fe = 4> resonance pumping can result in the ground state |Fg = 4, mF = 4> sublevel having a maximum population of 0.157 and the population difference would be about 0.01 in two adjacent magnetic sublevels of the hyperfine (HF) state Fg = 4. To enhance the anisotropy in the ground state, we suggest employing dichromatic optical HF pumping by adding a laser to excite D1 line |Fg = 4> → |Fe = 3> transition, in which the cesium magnetometer sensitivity increases by half a magnitude and is unaffected by the nonlinear Zeeman effect even in Earth's average magnetic field. (atomic and molecular physics)

  8. Experimental study of the profiles of the Hsub(β) and HeI 43D, 3F-23P spectral lines broadened by Stark or Stark-Zeeman effect

    International Nuclear Information System (INIS)

    The profiles of the Hsub(β) (lambda=4861.32A) and HeI(lambda=4471.48A and lambda=4470.04A) lines emitted during the recombination phase of pulsed plasmas confined by magnetic fields (02 molecular spectrum during the recombination phase; a very strong coupling between Stark effect and Zeeman effect: consequently, the components of the normal Zeeman effect are shifted as the electron density increases

  9. Stark broadening data for stellar plasma research.

    Science.gov (United States)

    Dimitrijević, M. S.

    Results of an effort to provide to astrophysicists and physicists an as much as possible complete set of Stark broadening parameters needed for stellar opacity calculations, stellar atmosphere modelling, abundance determinations and diagnostics of different plasmas in astrophysics, physics and plasma technology, are presented. Stark broadening has been considered within the semiclassical perturbation, and the modified semiempirical approaches.

  10. Experimental transition probabilities and Stark-broadening parameters of neutral and single ionized tin

    Science.gov (United States)

    Miller, M. H.; Roig, R. A.; Bengtson, R. D.

    1979-01-01

    Strengths and Stark-effect widths of the Sn I and Sn II lines prominent between 3200 and 7900 A are measured with a spectroscopic shock tube. Absolute strengths of 17 ionic lines are obtained with estimated (22-50)% accuracy and conform to appropriate quantum-mechanical sum rules. Relative transition probabilities for nine prominent neutral tin lines, normalized to radiative-lifetime data, are compared with other experiments and theoretical predictions. Parameters for Stark-effect broadening are measured over a range of plasma electron densities. Broadening data (with accuracies of 15-35%) for one neutral and ten ionic lines of tin are compared to theoretical predictions.

  11. Correction of Doppler-broadened Rayleigh backscattering effects in H2O dial measurements

    Science.gov (United States)

    Ansmann, A.; Bosenberg, J.

    1986-01-01

    A general method of solutions for treating effects of Doppler-broadened Rayleigh backscattering in H2O Differential Absorption Lidar (DIAL) measurements are described and discussed. Errors in vertical DIAL measuremtns caused by this laser line broadening effect can be very large and, therfore, this effect has to be accounted for accurately. To analyze and correct effects of Doppler-broadened Rayleigh backscattering in DIAL experiments, a generalized DIAL approximation was derived starting from a lidar equation, which includes Doppler broadening. To evaluate the accuracy of H2O DIAL measurements, computer simulations were performed. It was concluded that correction of Doppler broadened Rayleigh backscattering is possible with good accuracy in most cases of tropospheric H2O DIAL measurements, but great care has to be taken when layers with steep gradients of Mie backscattering like clouds or inversion layers are present.

  12. Interatomic potentials for the ground state X {sup 1}0{sup +} and the two excited states {sup 3}1, {sup 3}0{sup +} of the intercombination cadmium line 326.1 nm broadened by Kr pressure

    Energy Technology Data Exchange (ETDEWEB)

    Roston, G.D. [Physics Department, Faculty of Science, Alexandria University, P.O. Box 21511, Alexandria (Egypt)], E-mail: gamal_daniel@yahoo.com; Ghatass, Z.F. [Department of Environmental Studies, Institute of Graduate Studies and Research, Alexandria University, 163 Horrya Avenue, P.O. 832 Shatby, Alexandria (Egypt)

    2008-09-15

    The temperature dependence of the Cd line absorption profile at 326.1 nm perturbed by Kr has been carefully studied over a spectral range extending from 800 cm{sup -1} in the blue wing to 1200 cm{sup -1} in the red wing using a high-resolution double-beam spectrometer. The atomic densities of krypton (N{sub Kr}) and cadmium (N{sub Cd}) were (2.015{+-}0.07)x10{sup 19} and (3.62{+-}0.05)x10{sup 18} cm{sup -3}, respectively. The temperature dependence of the studied line profile was analyzed in the framework of the quasi-static theory. The van der Waals coefficient differences between the ground {sup 1}0{sup +} state and the two excited states {sup 3}0{sup +} and {sup 3}1 ({delta}C{sub 6}{sup 0} and {delta}C{sub 6}{sup 1}) were obtained from the near red wing profile using Kuhn's law. The values of {delta}C{sub 6}{sup 0} and {delta}C{sub 6}{sup 1} are found to be equal to 37.8{+-}2 and 58.5{+-}3 eV A{sup 6}, respectively. The ground (X {sup 1}0{sup +}), and the excited ({sup 3}1, {sup 3}0{sup +}) state potentials at the internuclear separations from 3.2 to 6.3 A were determined. The well depths with their positions for these states are respectively equal to 134{+-}7 cm{sup -1}, 3.95{+-}0.2 A; 72.3{+-}4 cm{sup -1}, 4.95{+-}0.3 A; and 471{+-}12 cm{sup -1}, 3.6 A. The obtained well depths with their allowable errors are in good agreement with the values obtained before for the Cd-Kr system from some theoretical results and molecular beams experiments.

  13. High resolution {sup 13}C NMR spectra on oriented lipid bilayers: From quantifying the various sources of line broadening to performing 2D experiments with 0.2-0.3 ppm resolution in the carbon dimension

    Energy Technology Data Exchange (ETDEWEB)

    Soubias, O.; Saurel, O.; Reat, V.; Milon, A. [Institut de Pharmacologie et de Biologie Structurale (France)], E-mail: alain.milon@ipbs.fr

    2002-09-15

    {sup 13}C NMR spectra routinely performed on oriented lipid bilayers display linewidth of 1-2 ppm, although T{sub 2} measurements indicate that 0.1-0.2 ppm could be obtained. We have prepared a DMPC - {sup 13}C{sub 4}-cholesterol (7/3) sample, and oriented the lipid bilayers between glass plates so that the bilayer normal makes an angle of 90 deg. (or of the magic angle) with B{sub 0}. We have measured T{sub 2}s, CSAs, and linewidths for the choline {sup 13}C-{gamma}-methyl, the cholesterol-C{sub 4} carbons and the lipid head group phosphorus, at both angles and 313 K. The magnetic field distribution within the sample was calculated using the surface current formalism. The line shapes were simulated as a function of B{sub 0} field inhomogeneities and sample mosaic spread. Both effects contribute to the experimental linewidth. Using three signals of different CSA, we have quantified both contributions and measured the mosaic spread accurately. Direct shimming on a sample signal is essential to obtain sharp resonances and {sup 13}C labelled choline methyl resonance of DMPC is a good candidate for this task. After optimisation of the important parameters (shimming on the choline resonance, mosaic spread of {+-} 0.30 deg.), {sup 13}C linewidth of 0.2-0.3 ppm have been obtained. This newly achieved resolution on bilayers oriented at 90 deg., has allowed to perform two 2D experiments, with a good sensitivity: 2D PELF (correlation of carbon chemical shifts and C-H dipolar couplings) and 2D D-resolved experiment (correlation of carbon chemical shifts and C-C dipolar couplings). A C-C dipolar coupling of 35 {+-} 2 Hz between the choline methyl carbons was determined.

  14. LINES

    Directory of Open Access Journals (Sweden)

    Minas Bakalchev

    2015-10-01

    Full Text Available The perception of elements in a system often creates their interdependence, interconditionality, and suppression. The lines from a basic geometrical element have become the model of a reductive world based on isolation according to certain criteria such as function, structure, and social organization. Their traces are experienced in the contemporary world as fragments or ruins of a system of domination of an assumed hierarchical unity. How can one release oneself from such dependence or determinism? How can the lines become less “systematic” and forms more autonomous, and less reductive? How is a form released from modernistic determinism on the new controversial ground? How can these elements or forms of representation become forms of action in the present complex world? In this paper, the meaning of lines through the ideas of Le Corbusier, Leonidov, Picasso, and Hitchcock is presented. Spatial research was made through a series of examples arising from the projects of the architectural studio “Residential Transformations”, which was a backbone for mapping the possibilities ranging from playfulness to exactness, as tactics of transformation in the different contexts of the contemporary world.

  15. Pulsed Spin Locking in Spin-1 NQR: Broadening Mechanisms

    Science.gov (United States)

    Malone, Michael W.

    Nuclear Quadrupole Resonance (NQR) is a branch of magnetic resonance physics that allows for the detection of spin I > 1/2 nuclei in crystalline and semi-crystalline materials. Through the application of a resonant radio frequency (rf) pulse, the nuclei's response is to create an oscillating magnetic moment at a frequency unique to the target substance. This creates the NQR signal, which is typically weak and rapidly decaying. The decay is due to the various line broadening mechanisms, the relative strengths of which are functions of the specific material, in addition to thermal relaxation processes. Through the application of a series of rf pulses the broadening mechanisms can be refocused, narrowing the linewidth and extending the signal in time. Three line broadening mechanisms are investigated to explain the NQR signal's linewidth and behavior. The first, electric field gradient (EFG) inhomogeneity, is due to variations in the local electric environment among the target nuclei, for instance from crystal imperfections. While EFG inhomogeneity can vary between samples of the same chemical composition and structure, the other broadening mechanisms of homonuclear and heteronuclear dipolar coupling are specific to this composition and structure. Simple analytical models are developed that explain the NQR signal response to pulse sequences by accounting for the behavior of each broadening mechanism. After a general theoretical introduction, a model of pairs of spin-1 nuclei is investigated, and the refocusing behaviors of EFG and homonuclear dipolar coupling are analyzed. This reveals the conditions where EFG is refocused but homonuclear dipolar coupling is not. In this case the resulting signal shows a rapid decay, the rate of which becomes a measure of interatomic distances. This occurs even in the more complex case of a powder sample with its many randomly oriented crystallites, under particular pulsing conditions. Many target NQR compounds are rich in hydrogen

  16. Density measurements using coherence imaging spectroscopy based on Stark broadening

    Energy Technology Data Exchange (ETDEWEB)

    Lischtschenko, O.; Bystrov, K.; De Temmerman, G. [Association EURATOM-FOM, FOM-Institute for Plasma Physics Rijnhuizen, partner in the Trilateral Euregio Cluster, P.O. Box 1207, 3430 BE Nieuwegein (Netherlands); Howard, J. [Research Laboratory, Australian National University, Canberra, Australian Capital Territory 0200 (Australia); Jaspers, R. J. E. [Fusion Group, Eindhoven University of Technology, Postbus 513, 5600 MB Eindhoven (Netherlands); Koenig, R. [EURATOM Association, Max-Planck-Institut fuer Plasmaphysik, TI Greifswald, Wendelsteinstr.1, D-17491 Greifswald (Germany)

    2010-10-15

    A coherence imaging camera has been set up at Pilot-PSI. The system is to be used for imaging the plasma density through the Stark effect broadening of the H{sub {gamma}} line. Local density values are then obtained by the Abel inversion of the measured interferometric fringe contrast. This report will present the instrument setup and proof-of-principle demonstration. The inverted spatial electron density profiles obtained near the cascaded arc source of Pilot-PSI in discharges with axial magnetic field of B=0.4 T are compared with an independent measurement of electron density by Thomson scattering and good agreement is found.

  17. Quasilinear Line Broadened Model for Energetic Particle Transport

    Science.gov (United States)

    Ghantous, Katy; Gorelenkov, Nikolai; Berk, Herbert

    2011-10-01

    We present a self-consistent quasi-linear model that describes wave-particle interaction in toroidal geometry and computes fast ion transport during TAE mode evolution. The model bridges the gap between single mode resonances, where it predicts the analytically expected saturation levels, and the case of multiple modes overlapping, where particles diffuse across phase space. Results are presented in the large aspect ratio limit where analytic expressions are used for Fourier harmonics of the power exchange between waves and particles, . Implemention of a more realistic mode structure calculated by NOVAK code are also presented. This work is funded by DOE contract DE-AC02-09CH11466.

  18. Sound pulse broadening in stressed granular media.

    Science.gov (United States)

    Langlois, Vincent; Jia, Xiaoping

    2015-02-01

    The pulse broadening and decay of coherent sound waves propagating in disordered granular media are investigated. We find that the pulse width of these compressional waves is broadened when the disorder is increased by mixing the beads made of different materials. To identify the responsible mechanism for the pulse broadening, we also perform the acoustic attenuation measurement by spectral analysis and the numerical simulation of pulsed sound wave propagation along one-dimensional disordered elastic chains. The qualitative agreement between experiment and simulation reveals a dominant mechanism by scattering attenuation at the high-frequency range, which is consistent with theoretical models of sound wave scattering in strongly random media via a correlation length. PMID:25768496

  19. Spectrally selective optical pumping in Doppler-broadened cesium atoms

    Institute of Scientific and Technical Information of China (English)

    Zhang Jun-Hai; Zeng Xian-Jin; Li Qing-Meng; Huang Qiang; Sun Wei-Min

    2013-01-01

    The D1 line spectrally selective pumping process in Doppler-broadened cesium is analyzed by solving the optical Bloch equations.The process,described by a three-level model with the A scheme,shows that the saturation intensity of broadened atoms is three orders of magnitude larger than that of resting atoms.The |Fg =3> → |Fe-4> resonance pumping can result in the ground state |Fg =4,mF =4> sublevel having a maximum population of 0.157 and the population difference would be about 0.01 in two adjacent magnetic sublevels of the hyperfine (HF) state Fg =4.To enhance the anisotropy in the ground state,we suggest employing dichromatic optical HF pumping by adding a laser to excite D1 line |Fg =4> → |Fe =3>transition,in which the cesium magnetometer sensitivity increases by half a magnitude and is unaffected by the nonlinear Zeeman effect even in Earth's average magnetic field.

  20. Collisional broadening of alkali doublets by helium perturbers

    CERN Document Server

    Mullamphy, D F T; Peach, G; Venturi, V; Whittingham, I B

    2006-01-01

    We report results for the Lorentzian profiles of the Li I, Na I and K I doublets and the Na I subordinate doublet broadened by helium perturbers for temperatures up to 3000 K They have been obtained from a fully quantum-mechanical close-coupling description of the colliding atoms, the Baranger theory of line shapes and new ab initio potentials for the alkali-helium interaction. For all lines except the 769.9 nm K I line, the temperature dependence of the widths over the range 70 < T < 3000 K is accurately represented by the power law form w=aT^b with 0.37 < b < 0.43. The 769.9 K I line has this form for 500 < T < 3000 K with b = 0.49. Although the shifts have a more complex temperature dependence, they all have the general feature of increasing with temperature above T=500 K apart from the 769.9 K I line whose shift decreases with temperature.

  1. Dynamic Stark broadening as the Dicke narrowing effect

    Science.gov (United States)

    Calisti, A.; Mossé, C.; Ferri, S.; Talin, B.; Rosmej, F.; Bureyeva, L. A.; Lisitsa, V. S.

    2010-01-01

    A very fast method to account for charged particle dynamics effects in calculations of spectral line shape emitted by plasmas is presented. This method is based on a formulation of the frequency fluctuation model (FFM), which provides an expression of the dynamic line shape as a functional of the static distribution of frequencies. Thus, the main numerical work rests on the calculation of the quasistatic Stark profile. This method for taking into account ion dynamics allows a very fast and accurate calculation of Stark broadening of atomic hydrogen high- n series emission lines. It is not limited to hydrogen spectra. Results on helium- β and Lyman- α lines emitted by argon in microballoon implosion experiment conditions compared with experimental data and simulation results are also presented. The present approach reduces the computer time by more than 2 orders of magnitude as compared with the original FFM with an improvement of the calculation precision, and it opens broad possibilities for its application in spectral line-shape codes.

  2. Anomalies of pressure broadening in the H{sub 2} {ital S}{sub 0}(3) transition versus perturber concentration

    Energy Technology Data Exchange (ETDEWEB)

    Anselm, N.; Schieder, R.; Winnewisser, G. [I. Physikalisches Institut, Universitaet zu Koeln, 50937 Koeln (Germany); Bonamy, J.; Robert, D. [Laboratoire de Physique Moleculaire, Universite de Franche-Comte, 25030 Besancon Cedex (France)

    1996-05-01

    {ital Inhomogeneous} {ital broadening} in vibrational {ital Q} lines for H{sub 2} broadened by heavy rare gases due to speed-changing collisions was previously demonstrated through the nonlinear behavior of the linewidths versus the concentration. In order to explore a possible inhomogeneous broadening (similar mechanism) for a pure rotational relaxation mechanism, the broadening and line shift of the pure rotational quadrupole transition {ital S}{sub 0}(3) of H{sub 2} have been measured to high precision with a frequency stabilized diode laser spectrometer. Foreign gas effects with helium and argon at various dilution ratios in H{sub 2} have been investigated. A nonlinear dependence of the broadening on the mixing ratio was detected in a pure rotational transition for the H{sub 2}-Ar mixture. This is the spectral signature expected for an inhomogeneous broadening due to speed-changing collisions. {copyright} {ital 1996 The American Physical Society.}

  3. Influence of elastic and inelastic collisions on density shift and broadening

    NARCIS (Netherlands)

    Weber, Erhard W.; Jungmann, Klaus-Peter

    1981-01-01

    For the Na D lines the shift and width of resolved hyperfine structure components are measured in He buffer gas with high-resolution laser saturation spectroscopy. The data obtained differ from those measured with Doppler-broadened optical spectroscopy. To explain the different values the existing d

  4. Particle size and strain broadening in energy-dispersive x-ray powder patterns

    DEFF Research Database (Denmark)

    Gerward, Leif; Mørup, Steen; Topsøe, Haldor

    1976-01-01

    An energy-dispersive x-ray method for a rapid analysis of the broadening of diffraction lines in powder patterns has been developed. Experimental results are given for magnetite powders with sizes in the range 50–200 Å and compared with the results of standard angle-dispersive diffractometry...

  5. Doppler broadening thermometry based on cavity ring-down spectroscopy

    CERN Document Server

    Cheng, C -F; Sun, Y R; Tan, Y; Kang, P; Hu, S -M

    2015-01-01

    A Doppler broadening thermometry (DBT) instrument is built based on cavity ring-down spectroscopy (CRDS) for precise determination of the Boltzmann constant. Compared with conventional direct absorption methods, the high-sensitivity of CRDS allows to reach a satisfied precision at lower sample pressures, which also reduces the influence due to collisions. By recording the spectrum of C$_2$H$_2$ at 787 nm, we demonstrate a statistical uncertainty of 6 ppm (part per million) in the determined linewidth values by several hours' measurement at a sample pressure of 1.5 Pa. The influence on the spectroscopy-determined temperatures has been investigated, including the "hidden" weak lines overlapped with the selected transition for DBT measurements. The reproducibility has also been examined to be better than 10 ppm, and it indicates that the instrument is feasible for DBT measurement toward a precision at the ppm level.

  6. Impact broadening of the dt. mu. formation resonances

    Energy Technology Data Exchange (ETDEWEB)

    Padial, N.T.; Cohen, J.S.; Leon, M.

    1988-08-01

    The density dependence of dt..mu.. molecular formation has been treated as a line-broadening process in the impact approximation. In the present paper, elastic cross sections and their coherent difference are calculated for D/sub 2/+D/sub 2/ and (dt..mu..)dee+D/sub 2/ collisions. Together with the rotationally inelastic cross sections previously calculated (Phys. Rev. A 37, 329 (1988)) using the same accurate intermolecular potential, this provides all cross sections needed for evaluation of the width in the impact approximation. The impact width is dominated by elastic scattering and, at the temperature 23 K and liquid-hydrogen density, has the value 14 meV, which is more than three times the previously calculated value.

  7. A broadened typology on energy and security

    International Nuclear Information System (INIS)

    A broadened typology describing the interconnection between energy and security is developed in this paper, with the aim of improving understanding of the relationship between energy and security by applying different research and policy perspectives. One approach involves studying energy as an object exposed to security threats, using concepts such as security of supply or security of demand. Another approach involves studying the role of the energy system as the subject in generating or enhancing insecurity. The latter approach includes studying the conflict-generating potential inherent in the economic value of energy, the risk of accidents and antagonistic attacks to energy infrastructure and the security risks related to the negative environmental impact of the energy system. In order to make a comprehensive analysis of the security consequences of proposed energy policies or strategies, all these aspects should be taken into account to varying degrees. The typology proposed here could be a valuable tool for ensuring that all security aspects have been considered. - Highlights: • The paper presents a broadened typology of energy and security, useful for policy analysis. • The energy system can be an object for security threats and as a subject generating or contributing to insecurity. • Energy as an object for security threats includes the concepts of security of supply and security of demand. • The economic value of energy can contribute to insecurity. • Technological and environmental risks of specific energy systems also provide potential threats to human security

  8. Action potential broadening in a presynaptic channelopathy

    Science.gov (United States)

    Begum, Rahima; Bakiri, Yamina; Volynski, Kirill E.; Kullmann, Dimitri M.

    2016-07-01

    Brain development and interictal function are unaffected in many paroxysmal neurological channelopathies, possibly explained by homoeostatic plasticity of synaptic transmission. Episodic ataxia type 1 is caused by missense mutations of the potassium channel Kv1.1, which is abundantly expressed in the terminals of cerebellar basket cells. Presynaptic action potentials of small inhibitory terminals have not been characterized, and it is not known whether developmental plasticity compensates for the effects of Kv1.1 dysfunction. Here we use visually targeted patch-clamp recordings from basket cell terminals of mice harbouring an ataxia-associated mutation and their wild-type littermates. Presynaptic spikes are followed by a pronounced afterdepolarization, and are broadened by pharmacological blockade of Kv1.1 or by a dominant ataxia-associated mutation. Somatic recordings fail to detect such changes. Spike broadening leads to increased Ca2+ influx and GABA release, and decreased spontaneous Purkinje cell firing. We find no evidence for developmental compensation for inherited Kv1.1 dysfunction.

  9. Commitment to Broadening Participation at NOAO

    Science.gov (United States)

    Garmany, Catharine D.; Norman, D.

    2011-01-01

    AURA and NOAO take seriously the importance of Broadening Participation in Astronomy. At the request of the AURA President, each of the AURA centers (NOAO, NSO, STSCI, Gemini) appointed a Diversity Advocates (DA). At NOAO this job is shared by Dara Norman and Katy Garmany, who were appointed by Dave Silva in Jan 2009. The DA's are members of the AURA Committee on Workforce and Diversity (WDC), a designated subcommittee of the AURA Board of Directors. The role of this committee includes reviewing activities and plans on an AURA wide basis aimed at broadening the participation within AURA, and reviewing AURA wide policies on the workforce. At NOAO, the role of the DAs spans a number of departments and activities. They serve on observatory search committees, and offer suggestions on how NOAO job searches can reach the most diverse audience. The DA's job is to insure that NOAO actively pursues every opportunity to increase diversity: to this end they are involved in outreach and educational activities that focus on workplace development and encourage inclusion of woman, minorities and persons with disabilities.

  10. Structure and broadening coefficients (He, Ar and N2) of the ν4 band of CF4

    International Nuclear Information System (INIS)

    Spectra of CF4 in the ν4 fundamental band region have been recorded in pure gas and in mixtures with He, Ar and N2 at resolution up to 0.003 cm-1. Obtained data allowed us to evaluate the integrated band intensity, line intensity distribution and effective broadening coefficients for J-multiplets. The broadening coefficient behavior is similar to that previously registered for linear molecules: they coincide for P and R branches; the J-dependence in the case of argon is more pronounced than that for helium. The broadening coefficients for nitrogen and helium are practically the same but the values for nitrogen are scattered around the general trend. Q-branch broadening is different from that for J-manifolds. The coefficients of branch broadening are noticeably smaller. Nitrogen broadening is very close to result for the case of argon though there is a marked difference between them for J-manifolds. Collisions with argon and nitrogen broaden the Q-branch almost 3 times more effectively than collisions with helium

  11. Broadening the focus of evaluation: An experiment

    Directory of Open Access Journals (Sweden)

    Chakraborty, S.

    2010-01-01

    Full Text Available Evaluation of student performance in any course, especially those delivered in a management programme, poses a serious challenge; more so, in a course like ‘Business Communication’, where oral communication ought to form an integral part of evaluation. This paper presents various details of an experiment, conducted with a view to introduce this much needed component in the evaluation process. Essential purpose of the exercise was to try and broaden the focus of evaluation, simultaneously enlarging its scope. The need to maintain certain amount of objectivity and transparency was taken as critical. Group Discussion was used as a tool. A process was developed with the objective of getting every student evaluated on both written as well as non-written skills. A two-sided evaluation mechanism was put in place to achieve the dual purpose of leaning and evaluation. Statistical analysis of the results suggests that the experiment was a useful one. The student feedback, too, was favourable.

  12. Analysis of pressure-broadened ozone spectra in the 3 micron region

    Science.gov (United States)

    Prochaska, Eleanor S.

    1991-01-01

    This work involves the analysis of a series of McMath Fourier Transform Infrared (FTIR) spectra of ozone broadened by mixing with air (four different pressures), nitrogen (three pressures), or oxygen (three pressures). Each spectrum covers the region from 2396 to 4057 cm(-1). This study focused on the 3 sub nu sub 3 band in t 3000 to 3060 cm(-1). The band is analyzed by first dividing its region into small intervals containing a few well isolated absorption lines of reasonable intensity. Each of these small intervals is fit by multiple iterations of the nonlinear least squares program until residuals (the difference between calculated and observed spectrum, as a percent of the strongest intensity in the interval) are minimized to a reasonable value which corresponds to the noise level of the measured spectrum. Position, intensity, and half-width are recorded for later analysis. From the measured half-widths, a pressure broadening coefficient was determined for each absorption line. Pressure shifts were determined by comparing observed line positions in the spectra of the diluted ozone samples to tabulated line positions determined from spectra of pure gas samples. Comparisons to other work on ozone indicate that the broadening and shift coefficients determined in this study are consistent with those determined in other spectral regions.

  13. Study of Compton Broadening Due to Electron-Photon Scattering

    Directory of Open Access Journals (Sweden)

    Srinivasa Rao, M.

    2010-06-01

    Full Text Available We have investigated the effects of Compton broadening due to electron-photon scattering in hot stellar atmospheres. A purely electron-photon scattering media is assumed to have plane parallel geometry with an input radiation field localized on one side of the slab. The method is based on the discrete space theory of radiative transfer for the intensity of emitted radiation.The solution is developed to study the importance of scattering of radiation by free electrons in high temperature stellar atmospheres which produces a brodening and shift in spectral lines because of the Compton effect and the Doppler effect arising from mass and thermal motions of scattering electrons.It is noticed that the Comptonized spectrum depends on three parameters: the optical depth of the medium, the temperature of the thermal electrons and the viewing angle.We also showed that the Compton effect produces red shift and asymmetry in the line. These two effects increase as the optical depth increases. It is also noticed that the emergent specific intensities become completely asymmetric for higher optical depths.

  14. Parton Energy Loss and Momentum Broadening at NLO in High Temperature QCD Plasmas

    Science.gov (United States)

    Ghiglieri, Jacopo; Teaney, Derek

    We present an overview of a perturbative-kinetic approach to jet propagation, energy loss, and momentum broadening in a high temperature quark-gluon plasma. The leading-order kinetic equations describe the interactions between energetic jet-particles and a non-abelian plasma, consisting of on-shell thermal excitations and soft gluonic fields. These interactions include 2 ↔ 2 scatterings, collinear bremsstrahlung, and drag and momentum diffusion. We show how the contribution from the soft gluonic fields can be factorized into a set of Wilson line correlators on the light-cone. We review recent field-theoretical developments, rooted in the causal properties of these correlators, which simplify the calculation of the appropriate Wilson lines in thermal field theory. With these simplifications lattice measurements of transverse momentum broadening have become possible, and the kinetic equations describing parton transport have been extended to next-to-leading order in the coupling g.

  15. Parton energy loss and momentum broadening at NLO in high temperature QCD plasmas

    CERN Document Server

    Ghiglieri, Jacopo

    2015-01-01

    We present an overview of a perturbative-kinetic approach to jet propagation, energy loss, and momentum broadening in a high temperature quark-gluon plasma. The leading-order kinetic equations describe the interactions between energetic jet-particles and a non-abelian plasma, consisting of on-shell thermal excitations and soft gluonic fields. These interactions include 22 scatterings, collinear bremsstrahlung, and drag and momentum diffusion. We show how the contribution from the soft gluonic fields can be factorized into a set of Wilson line correlators on the light cone. We review recent field-theoretical developments, rooted in the causal properties of these correlators, which simplify the calculation of the appropriate Wilson lines in thermal field theory. With these simplifications lattice measurements of transverse momentum broadening have become possible, and the kinetic equations describing parton transport have been extended to next-to-leading order in the coupling g.

  16. Electron Density and Temperature Measurement by Stark Broadening in a Cold Argon Arc-Plasma Jet at Atmospheric Pressure

    Institute of Scientific and Technical Information of China (English)

    ZHOU Qiuping; CHENG Cheng; MENG Yuedong

    2009-01-01

    Determination of both the electron density and temperature simultaneously in a cold argon arc-plasma jet by analyzing the Stark broadening of two different emission lines is presented.This method is based on the fact that the Stark broadening of different lines has a different dependence on the electron density and temperature.Therefore,a comparison of two or more line broadenings allows us to diagnose the electron density and temperature simultaneously.In this study we used the first two Balmer series hydrogen lines H_α and H_β for their large broadening width.For this purpose,a small amount of hydrogen was introduced into the discharge gas.The results of the Gigosos-Cardenoso computational model,considering more relevant processes for the hydrogen Balmer lines,is used to process the experimental data.With this method,we obtained reliable electron density and temperature,1.88 ×10 ~(15) cm~(-3 )and 13000 K,respectively.Possible sources of error were also analyzed.

  17. Observation of Doppler broadening in $\\beta$-delayed proton-$\\gamma$ decay

    CERN Document Server

    Schwartz, S B; Bennett, M B; Liddick, S N; Perez-Loureiro, D; Bowe, A; Chen, A A; Chipps, K A; Cooper, N; Irvine, D; McNeice, E; Montes, F; Naqvi, F; Ortez, R; Pain, S D; Pereira, J; Prokop, C; Quaglia, J; Quinn, S J; Sakstrup, J; Santia, M; Shanab, S; Simon, A; Spyrou, A; Thiagalingam, E

    2015-01-01

    Background: The Doppler broadening of $\\gamma$-ray peaks due to nuclear recoil from $\\beta$-delayed nucleon emission can be used to measure the energies of the nucleons. This method has never been tested using $\\beta$-delayed proton emission or applied to a recoil heavier than $A=10$. Purpose: To test and apply this Doppler broadening method using $\\gamma$-ray peaks from the $^{26}$P($\\beta p\\gamma$)$^{25}$Al decay sequence. Methods: A fast beam of $^{26}$P was implanted into a planar Ge detector, which was used as a $^{26}$P $\\beta$-decay trigger. The SeGA array of high-purity Ge detectors was used to detect $\\gamma$ rays from the $^{26}$P($\\beta p\\gamma$)$^{25}$Al decay sequence. Results: Radiative Doppler broadening in $\\beta$-delayed proton-$\\gamma$ decay was observed for the first time. The Doppler broadening analysis method was verified using the 1613 keV $\\gamma$-ray line for which the proton energies were previously known. The 1776 keV $\\gamma$ ray de-exciting the 2720 keV $^{25}$Al level was observed...

  18. The IACOB project: III. New observational clues to understand macroturbulent broadening in massive O- and B-type stars

    CERN Document Server

    Simón-Díaz, S; Castro, N; Herrero, A; Aerts, C; Puls, J; Telting, J; Grassitelli, L

    2016-01-01

    We aim to provide new empirical clues about macroturbulent spectral line broadening in O- and B-type stars to evaluate its physical origin. We use high-resolution spectra of ~430 stars with spectral types in the range O4-B9 (all luminosity classes). We characterize the line-broadening of adequate diagnostic metal lines using a combined FT and GOF technique. We perform a quantitative spectroscopic analysis of the whole sample using automatic tools coupled with a huge grid of FASTWIND models. We also incorporate quantitative information about line asymmetries to our observational description of the characteristics of the line-profiles, and present a comparison of the shape and type of line-profile variability found in a small sample of O stars and B supergiants with still undefined pulsational properties and B main sequence stars with variable line-profiles. We present a homogeneous and statistically significant overview of the (single snapshot) line-broadening properties of stars in the whole O and B star doma...

  19. Linewidth broadening and emission saturation of a resonantly excited quantum dot monitored via an off-resonant cavity mode

    DEFF Research Database (Denmark)

    Ulhaq, A.; Ates, Serkan; Weiler, S.;

    2010-01-01

    We report on the robustness of a detuned mode channel for reading out the relevant s-shell properties of a resonantly excited coupled quantum dot (QD) in a pillar microcavity. The line broadening of the QD s-shell is “monitored” by the mode signal with high conformity to the directly measured QD ...

  20. A Global Fitting Approach For Doppler Broadening Thermometry

    Science.gov (United States)

    Amodio, Pasquale; Moretti, Luigi; De Vizia, Maria Domenica; Gianfrani, Livio

    2014-06-01

    Very recently, a spectroscopic determination of the Boltzmann constant, kB, has been performed at the Second University of Naples by means of a rather sophisticated implementation of Doppler Broadening Thermometry (DBT)1. Performed on a 18O-enriched water sample, at a wavelength of 1.39 µm, the experiment has provided a value for kB with a combined uncertainty of 24 parts over 106, which is the best result obtained so far, by using an optical method. In the spectral analysis procedure, the partially correlated speed-dependent hard-collision (pC-SDHC) model was adopted. The uncertainty budget has clearly revealed that the major contributions come from the statistical uncertainty (type A) and from the uncertainty associated to the line-shape model (type B)2. In the present work, we present the first results of a theoretical and numerical work aimed at reducing these uncertainty components. It is well known that molecular line shapes exhibit clear deviations from the time honoured Voigt profile. Even in the case of a well isolated spectral line, under the influence of binary collisions, in the Doppler regime, the shape can be quite complicated by the joint occurrence of velocity-change collisions and speed-dependent effects. The partially correlated speed-dependent Keilson-Storer profile (pC-SDKS) has been recently proposed as a very realistic model, capable of reproducing very accurately the absorption spectra for self-colliding water molecules, in the near infrared3. Unfortunately, the model is so complex that it cannot be implemented into a fitting routine for the analysis of experimental spectra. Therefore, we have developed a MATLAB code to simulate a variety of H218O spectra in thermodynamic conditions identical to the one of our DBT experiment, using the pC-SDKS model. The numerical calculations to determine such a profile have a very large computational cost, resulting from a very sophisticated iterative procedure. Hence, the numerically simulated spectra

  1. Phase modulation of propagation effect with Doppler broadening

    Institute of Scientific and Technical Information of China (English)

    Qiao Hong-Xia; Yang Yan-Ling; Tan Xia; Tong Dian-Min; Fan Xi-Jun

    2008-01-01

    This paper studies the propagation effect in a closed lambda-type three-level atomic system with Doppler broadening.It is shown that,Doppler broadening due to atomic motion and propagation effect associated with driving field depletion along the active medium decreases obviously the gain and output of the lasing without inversion(LWI);the relative phase between the probe and driving fields has a remarkable modulation role to the propagation effect on LWI when Doppler broadening presents;by choosing suitable value of the relative phase,we can get the largest gain and output of LWI.

  2. Temporal broadening of pulsed waves propagating through turbulent media

    Institute of Scientific and Technical Information of China (English)

    XU; Zhengwen(许正文); WU; Jian(吴健); HUO; Wenping(霍文平); WU; Zhensen(吴振森)

    2003-01-01

    Pulse signals, propagating through a turbulent medium such as the ionosphere, can be distorted by dispersion and scattering from both the background medium and irregularities embedded in. Thus, the mean square pulse width is changed, and temporal broadening is introduced. We carry out a study on the temporal broadening with theoretical analyses and numerical simulations by using an analytical solution of two-frequency mutual coherence function obtained recently by iteration. As a case of study, pulse broadening is investigated in detail in trans-ionospheric propagation. Results show that most contributions are mainly from the dispersion of the background ionosphere and scattering effects of electron density irregularities in most cases.

  3. Medium Induced Transverse Momentum Broadening in Hard Processes

    CERN Document Server

    Mueller, A H; Xiao, Bo-Wen; Yuan, Feng

    2016-01-01

    Using deep inelastic scattering on a large nucleus as an example, we consider the transverse momentum broadening of partons in hard processes in the presence of medium. We find that one can factorize the vacuum radiation contribution and medium related $P_T$ broadening effects into the Sudakov factor and medium dependent distributions, respectively. Our derivations can be generalized to other hard processes, such as dijet productions, which can be used as a probe to measure the medium $P_T$ broadening effects in heavy ion collisions when Sudakov effects are not overwhelming.

  4. Spectral broadening in anatase titanium dioxide waveguides at telecommunication and near-visible wavelengths.

    Science.gov (United States)

    Evans, Christopher C; Shtyrkova, Katia; Bradley, Jonathan D B; Reshef, Orad; Ippen, Erich; Mazur, Eric

    2013-07-29

    We observe spectral broadening of femtosecond pulses in single-mode anatase-titanium dioxide (TiO(2)) waveguides at telecommunication and near-visible wavelengths (1565 and 794 nm). By fitting our data to nonlinear pulse propagation simulations, we quantify nonlinear optical parameters around 1565 nm. Our fitting yields a nonlinear refractive index of 0.16 × 10(-18) m(2)/W, no two-photon absorption, and stimulated Raman scattering from the 144 cm(-1) Raman line of anatase with a gain coefficient of 6.6 × 10(-12) m/W. Additionally, we report on asymmetric spectral broadening around 794 nm. The wide wavelength applicability and negligible two-photon absorption of TiO(2) make it a promising material for integrated photonics.

  5. Positron life time and annihilation Doppler broadening measurements on transition metal complexes

    Energy Technology Data Exchange (ETDEWEB)

    Levay, B. (Eoetvoes Lorand Tudomanyegyetem, Budapest (Hungary). Fizikai Kemiai es Radiologiai Tanszek); Varhelyi, Cs. (Babes-Bolyai Univ., Cluj (Romania)); Burger, K. (Eoetvoes Lorand Tudomanyegyetem, Budapest (Hungary). Szervetlen es Analitikai Kemiai Intezet)

    1982-01-01

    Positron life time and annihilation Doppler broadening measurements have been carried out on 44 solid coordination compounds. Several correlations have been found between the annihilation life time (tau/sub 1/) and line shape parameters (L) and the chemical structure of the compounds. Halide ligands were the most active towards positrons. This fact supports the assumption on the possible formation of (e/sup +/X/sup -/) positron-halide bound state. The life time was decreasing and the annihilation energy spectra were broadening with the increasing negative character of the halides. The aromatic base ligands affected the positron-halide interaction according to their basicity and space requirement and thus they indirectly affected the annihilation parameters, too. In the planar and tetrahedral complexes the electron density on the central met--al ion affected directly the annihilation parameters, while in the octahedral mixed complexes it had only an ind--irect effect through the polarization of the halide ligands.

  6. Determination of the Ion Velocity Distribution in a Rotating Plasma from Measurements of Doppler Broadening

    DEFF Research Database (Denmark)

    Jørgensen, L. W.; Sillesen, Alfred Hegaard

    1979-01-01

    -particle orbit picture is valid for the discharge period under investigation, except for the first few microseconds during breakdown when a strong interaction between plasma and remaining neutral gas takes place by Alfvens critical velocity mechanism. A simple relation is given between the measured half......The Doppler-broadened profile of the He II 4685.75 AA line was measured along a chord in a rotating plasma, transverse to the magnetic field. Using a single-particle orbit picture, the corresponding velocity spectrum of ions confirm the measurements, so it can be concluded that the single......-width and shift of the Doppler profile and the macroscopic quantities of ion velocity and energy. Several Doppler-broadened profiles are shown for different plasma parameters....

  7. Shifts and broadenings of barium Rydberg states perturbed by inert gases

    Energy Technology Data Exchange (ETDEWEB)

    Marafi, M; Suji, Z; Bhatia, K; Makdisi, Y; Mathew, J [Department of Physics, Kuwait University, PO Box-5969, 13060-Safat (Kuwait)

    2007-11-14

    Collisional broadening and shift data for even parity states of neutral barium are presented. A two-photon absorption technique is used to populate Rydberg states of nd {sup 1}D{sub 2}, {sup 3}D{sub 2} and {sup 1}S{sub 0} series. High-resolution Ba excitation spectra were measured using a diode detector while scanning the frequency of an excimer pumped dye laser. Inert gases Ar, Kr and Xe were used as perturbers at pressures ranging from 10 mb to 400 mb. Shifts and broadenings of spectral lines were measured as a function of pressure and principal quantum number n. Several perturbations and deviations from expected results are discussed in this paper.

  8. Spectroscopic properties of inhomogeneously broadened spin ensembles in a cavity

    DEFF Research Database (Denmark)

    Kurucz, Zoltan; Wesenberg, Janus; Mølmer, Klaus

    2011-01-01

    The enhanced collective coupling to weak quantum fields may turn atomic or spin ensembles into an important component in quantum information processing architectures. Inhomogeneous broadening can, however, significantly reduce the coupling and the lifetime of the collective excitation...

  9. Solar Wind Strahl Broadening by Self-Generated Plasma Waves

    Science.gov (United States)

    Pavan, J.; Vinas, A. F.; Yoon, P. H.; Ziebell, L. F.; Gaelzer, R.

    2013-01-01

    This Letter reports on the results of numerical simulations which may provide a possible explanation for the strahl broadening during quiet solar conditions. The relevant processes involved in the broadening are due to kinetic quasi-linear wave-particle interaction. Making use of static analytical electron distribution in an inhomogeneous field, it is found that self-generated electrostatic waves at the plasma frequency, i.e., Langmuir waves, are capable of scattering the strahl component, resulting in energy and pitch-angle diffusion that broadens its velocity distribution significantly. The present theoretical results provide an alternative or complementary explanation to the usual whistler diffusion scenario, suggesting that self-induced electrostatic waves at the plasma frequency might play a key role in broadening the solar wind strahl during quiet solar conditions.

  10. Meta-Research: Broadening the Scope of PLOS Biology.

    Science.gov (United States)

    Kousta, Stavroula; Ferguson, Christine; Ganley, Emma

    2016-01-01

    In growing recognition of the importance of how scientific research is designed, performed, communicated, and evaluated, PLOS Biology announces a broadening of its scope to cover meta-research articles.

  11. Self-phase-modulation induced spectral broadening in silicon waveguides

    Science.gov (United States)

    Boyraz, Ozdal; Indukuri, Tejaswi; Jalali, Bahram

    2004-03-01

    The prospect for generating supercontinuum pulses on a silicon chip is studied. Using ~4ps optical pulses with 2.2GW/cm2 peak power, a 2 fold spectral broadening is obtained. Theoretical calculations, that include the effect of two-photon-absorption, indicate up to 5 times spectral broadening is achievable at 10x higher peak powers. Representing a nonlinear loss mechanism at high intensities, TPA limits the maximum optical bandwidth that can be generated.

  12. Stark broadening of the hydrogen resonances Lsub(α) and Lsub(β) in high density plasmas

    International Nuclear Information System (INIS)

    As a concluding remark it can be noted that the foregoing Lsub(α) and Lsub(β) experiments only allowed a limited examination of the theories of the STARK-broadening. Above all the results of the central region of Lsub(α) and Lsub(β) were missing that are necessary for a critical evaluation of the mechanism of the broadening. It was the goal of this work to investigate the STARK-broadening of the resonances Lsub(α) and Lsub(β) especially in the central profile of the region. It was necessary for a performance of the measurement to simultaneously realize the following experimental conditions: the generation of sufficient thin optical line profiles, avoidance of reabsorption in the border zones of the plasma, generation of high electron densities in way that the STARK-part is dominant over the DOPPLER-part. (orig./HT)

  13. Accurate modeling of size and strain broadening in the Rietveld refinement: The {open_quotes}double-Voigt{close_quotes} approach

    Energy Technology Data Exchange (ETDEWEB)

    Balzar, D. [Ruder Boskovic Inst., Zagreb (Croatia); Ledbetter, H. [National Inst. of Standards and Technology, Boulder, CO (United States)

    1995-12-31

    In the {open_quotes}double-Voigt{close_quotes} approach, an exact Voigt function describes both size- and strain-broadened profiles. The lattice strain is defined in terms of physically credible mean-square strain averaged over a distance in the diffracting domains. Analysis of Fourier coefficients in a harmonic approximation for strain coefficients leads to the Warren-Averbach method for the separation of size and strain contributions to diffraction line broadening. The model is introduced in the Rietveld refinement program in the following way: Line widths are modeled with only four parameters in the isotropic case. Varied parameters are both surface- and volume-weighted domain sizes and root-mean-square strains averaged over two distances. Refined parameters determine the physically broadened Voigt line profile. Instrumental Voigt line profile parameters are added to obtain the observed (Voigt) line profile. To speed computation, the corresponding pseudo-Voigt function is calculated and used as a fitting function in refinement. This approach allows for both fast computer code and accurate modeling in terms of physically identifiable parameters.

  14. New determination of the core-level life-time broadenings in mercury

    International Nuclear Information System (INIS)

    Highlights: • We report core-level life-time widths for mercury in the gas phase. • Photoelectron spectra for the 4p, 4d, 4f and 5p levels are analyzed. • A Coster–Kronig like CI effect is observed for the 4d3/2 level. - Abstract: Previously recorded and published photoelectron spectroscopic data for mercury in the gas phase has been reanalyzed. The life-time broadenings have been determined for a large number of core levels. It is then seen that a recent detailed derivation of core-level line-widths based on X-ray emission spectroscopy give life-time widths that are generally too large. The 4d3/24d5/2nd Coster–Kronig (CK) transition is also discussed. We find that the additional broadening of the 4d3/2 level for mercury metal is indeed due to a CK decay, in contrast to recent claims. In atomic mercury, however, the CK process in energetically forbidden. In spite of this we find that the 4d3/2 level is broadened also in this case. We propose that this is due to a mixing between the 4d3/2 hole state and discrete 4d5/2nd states

  15. Toward a Broadband Astro-comb: Effects of Nonlinear Spectral Broadening in Optical Fibers

    CERN Document Server

    Chang, Guoqing; Phillips, David F; Walsworth, Ronald L; Kärtner, Franz X

    2010-01-01

    We propose and analyze a new approach to generate a broadband astro-comb by spectral broadening of a narrowband astro-comb inside a highly nonlinear optical fiber. Numerical modeling shows that cascaded four-wave-mixing dramatically degrades the input comb's side-mode suppression and causes side-mode amplitude asymmetry. These two detrimental effects can systematically shift the center-of-gravity of astro-comb spectral lines as measured by an astrophysical spectrograph with resolution \\approx100,000; and thus lead to wavelength calibration inaccuracy and instability. Our simulations indicate that this performance penalty, as a result of nonlinear spectral broadening, can be compensated by using a filtering cavity configured for double-pass. As an explicit example, we present a design based on an Yb-fiber source comb (with 1 GHz repetition rate) that is filtered by double-passing through a low finesse cavity (finesse = 208), and subsequent spectrally broadened in a 2-cm, SF6-glass photonic crystal fiber. Spann...

  16. Sensitivity Enhancement in Field-Modulated CW ENDOR via RF Bandwidth Broadening

    Science.gov (United States)

    Hoffman, B. M.; Derose, V. J.; Ong, J. L.; Davoust, C. E.

    In low-temperature ENDOR studies it is common to modulate the magnetic field at ν mod ˜ 100 kHz and to observe the ENDOR response as a change in the dispersion-mode rapid-passage EPR signal as decoded at ν mod. The sensitivity of this procedure can be increased by incoherently broadening the bandwidth of the applied RF through mixing of the RF carrier signal with a white-noise source of variable bandwidth. This technique has been explored by monitoring the amplitude and width of ENDOR signals as a function of the RF bandwidth and power, in the case of the 57Fe signals from a metalloprotein and 14N, 1H signals from two Cu(II) compounds. The RF band broadening has produced signal enhancements of over threefold. The results are interpreted in terms of a competition between (i) an increase in the number of spin packets excited within the inhomogeneously broadened ENDOR line and () a reduction in the response per packet. Simple analysis leads to equations for the variation in the ENDOR response with incident RF power and bandwidth that are scaled by a saturation RF power and an effective spin-packet width, respectively.

  17. New determination of the core-level life-time broadenings in mercury

    Energy Technology Data Exchange (ETDEWEB)

    Martensson, Nils, E-mail: nils.martensson@fysik.uu.se; Svensson, Svante

    2015-07-15

    Highlights: • We report core-level life-time widths for mercury in the gas phase. • Photoelectron spectra for the 4p, 4d, 4f and 5p levels are analyzed. • A Coster–Kronig like CI effect is observed for the 4d{sub 3/2} level. - Abstract: Previously recorded and published photoelectron spectroscopic data for mercury in the gas phase has been reanalyzed. The life-time broadenings have been determined for a large number of core levels. It is then seen that a recent detailed derivation of core-level line-widths based on X-ray emission spectroscopy give life-time widths that are generally too large. The 4d{sub 3/2}4d{sub 5/2}nd Coster–Kronig (CK) transition is also discussed. We find that the additional broadening of the 4d{sub 3/2} level for mercury metal is indeed due to a CK decay, in contrast to recent claims. In atomic mercury, however, the CK process in energetically forbidden. In spite of this we find that the 4d{sub 3/2} level is broadened also in this case. We propose that this is due to a mixing between the 4d{sub 3/2} hole state and discrete 4d{sub 5/2}nd states.

  18. Effects of 946-nm thermal shift and broadening on Nd3+:YAG laser performance

    Science.gov (United States)

    Seyed Ebrahim, Pourmand; Ghasem, Rezaei

    2015-12-01

    Spectroscopic properties of flashlamp pumped Nd3+:YAG laser are studied as a function of temperature in a range from -30 °C to 60 °C. The spectral width and shift of quasi three-level 946.0-nm inter-Stark emission within the respective intermanifold transitions of 4F3/2 → 4I9/2 are investigated. The 946.0-nm line shifts toward the shorter wavelength and broadens. In addition, the threshold power and slope efficiency of the 946.0-nm laser line are quantified with temperature. The lower the temperature, the lower the threshold power is and the higher the slope efficiency of the 946.0-nm laser line is, thus the higher the laser output is. This phenomenon is attributed to the ion-phonon interaction and the thermal population in the ground state. Project supported by Estahban Branch, Islamic Azad University.

  19. Intensities, broadening and narrowing parameters in the ν3 band of methane

    KAUST Repository

    Es-sebbar, Et-touhami

    2014-12-01

    The P-branch of methane\\'s ν3 band is probed to carry out an extensive study of the 2905-2908cm-1 infrared spectral region. Absolute line intensities as well as N2-, O2-, H2-, He-, Ar- and CO2-broadening coefficients are determined for nine transitions at room temperature. Narrowing parameters due to the Dicke effect have also been investigated. A narrow emission line-width (~0.0001cm-1) difference-frequency-generation (DFG) laser system is used as the tunable light source. To retrieve the CH4 spectroscopic parameters, Voigt and Galatry profiles were used to simulate the measured line shape of the individual transitions.

  20. Opacity broadening and interpretation of suprathermal CO linewidths: Macroscopic Turbulence and Tangled Molecular Clouds

    CERN Document Server

    Hacar, A; Burkert, A; Goldsmith, P

    2016-01-01

    (Abridged) Many of the observed CO line profiles exhibit broad linewidths that greatly exceed the thermal broadening expected within molecular clouds. These suprathermal CO linewidths are assumed to be originated from the presence of unresolved supersonic motions inside clouds. Typically overlooked in the literature, in this paper we aim to quantify the impact of the opacity broadening effects on the current interpretation of the CO suprathermal line profiles. Without any additional contributions to the gas velocity field, a large fraction of the apparently supersonic (${\\cal M}\\sim$2-3) linewidths measured in both $^{12}$CO and $^{13}$CO (J=1-0) lines can be explained by the saturation of their corresponding sonic-like, optically-thin C$^{18}$O counterparts assuming standard isotopic fractionation. Combined with the presence of multiple components detected in our C$^{18}$O spectra, these opacity effects seem to be also responsible of the highly supersonic linewidths (${\\cal M}>$8-10) detected in the broadest...

  1. Doppler broadening of in-flight positron annihilation radiation due to electron momentum.

    Science.gov (United States)

    Hunt, A W; Cassidy, D B; Sterne, P A; Cowan, T E; Howell, R H; Lynn, K G; Golevchenko, J A

    2001-06-11

    We report the first observation of electron momentum contributions to the Doppler broadening of radiation produced by in-flight two-photon annihilation in solids. In these experiments an approximately 2.5 MeV positron beam impinged on thin polyethylene, aluminum, and gold targets. Since energetic positrons easily penetrate the nuclear Coulomb potential and do not cause a strong charge polarization, the experimental annihilation line shapes agree well with calculations based on a simple independent-particle model. Moreover, annihilations with the deepest core electrons are greatly enhanced.

  2. Broadening Industry Governance to Include Nonproliferation

    Energy Technology Data Exchange (ETDEWEB)

    Hund, Gretchen; Seward, Amy M.

    2008-11-11

    As industry is the first line of defense in detecting and thwarting illicit trade networks, the engagement of the private sector is critical to any government effort to strengthen existing mechanisms to protect goods and services throughout the supply chain. This study builds on previous PNNL work to continue to evaluate means for greater industry engagement to complement and strengthen existing governmental efforts to detect and stem the trade of illicit goods and to protect and secure goods that could be used in making a weapon of mass destruction. Specifically, the study evaluates the concept of Industry Self Regulation, defined as a systematic voluntary program undertaken by an industry or by individual companies to anticipate, implement, supplement, or substitute for regulatory requirements in a given field, generally through the adoption of best practices. Through a series of interviews with companies with a past history of non-compliance, trade associations and NGOs, the authors identify gaps in the existing regulatory infrastructure, drivers for a self regulation approach and the form such an approach might take, as well as obstacles to be overcome. The authors conclude that it is at the intersection of industry, government, and security that—through collaborative means—the effectiveness of the international nonproliferation system—can be most effectively strengthened to the mutual benefit of both government and the private sector. Industry has a critical stake in the success of this regime, and has the potential to act as an integrating force that brings together the existing mechanisms of the global nonproliferation regime: export controls, physical protection, and safeguards. The authors conclude that industry compliance is not enough; rather, nonproliferation must become a central tenant of a company’s corporate culture and be viewed as an integral component of corporate social responsibility (CSR).

  3. Broadening of Transverse Momentum of Partons Propagating through a Medium

    CERN Document Server

    Johnson, M B; Tarasov, A V

    2001-01-01

    Broadening of the transverse momentum of a parton propagating through a medium is treated using the color dipole formalism, which has the advantage of being a well developed phenomenology in deep-inelastic scattering and soft processes. Within this approach, nuclear broadening should be treated as color filtering, i.e. absorption of large-size dipoles leading to diminishing (enlarged) transverse separation (momentum). We also present a more intuitive derivation based on the classic scattering theory of Moli\\`ere. This derivation helps to understand the origin of the dipole cross section, part of which comes from attenuation of the quark, while another part is due to multiple interactions of the quark. It also demonstrates that the lowest-order rescattering term provides an A-dependence very different from the generally accepted A^{1/3} behavior. The effect of broadening increases with energy, and we evaluate it using different phenomenological models for the unintegrated gluon density. Although the process is...

  4. Multigroup Free-atom Doppler-broadening Approximation. Theory

    Energy Technology Data Exchange (ETDEWEB)

    Gray, Mark Girard [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-11-06

    Multigroup cross sections at a one target temperature can be Doppler-broadened to multigroup cross sections at a higher target temperature by matrix multiplication if the group structure suf- ficiently resolves the original temperature continuous energy cross section. Matrix elements are the higher temperature group weighted averages of the integral over the lower temperature group boundaries of the free-atom Doppler-broadening kernel. The results match theory for constant and 1/v multigroup cross sections at 618 lanl group structure resolution.

  5. Combustion technology overview. [the use of broadened property aircraft fuels

    Science.gov (United States)

    Niedzwiecki, R. W.

    1980-01-01

    An overview of combustor technology developments required for use of broadened property fuels in jet aircraft is presented. The intent of current investigations is to determine the extent to which fuel properties can be varied, to obtain a data base of combustion - fuel quality effects, and to determine the trade-offs associated with broadened property fuels. Subcomponents of in-service combustors such as fuel injectors and liners, as well as air distributions and stoichiometry, are being altered to determine the extent to which fuel flexibility can be extended. Finally, very advanced technology consisting of new combustor concepts is being evolved to optimize the fuel flexibility of gas turbine combustors.

  6. Study of peak broadening effect in floor time histories

    International Nuclear Information System (INIS)

    Seismic design of secondary systems such components and piping is usually carried out by using the floor motions at their support points. These floor motions can be in the form of Floor Response Spectra (FRS) or the Floor Time Histories (FTH). In order to account for the various uncertainties in generating these floor motions, these motions should be peak broadened and smoothened as per the regulatory codes. Presented here in this paper is the methodology to account for such peak broadening effect in the FTH. Results of this study have been compared with the FRS approach and various important conclusions have been arrived at based on the study

  7. Multigroup Free-atom Doppler-broadening Approximation. Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Gray, Mark Girard [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-11-06

    The multigroup energy Doppler-broadening approximation agrees with continuous energy Dopplerbroadening generally to within ten percent for the total cross sections of 1H, 56Fe, and 235U at 250 lanl. Although this is probably not good enough for broadening from room temperature through the entire temperature range in production use, it is better than any interpolation scheme between temperatures proposed to date, and may be good enough for extrapolation from high temperatures. The method deserves further study since additional improvements are possible.

  8. Optical coherent control in semiconductors: Fringe contrast and inhomogeneous broadening

    DEFF Research Database (Denmark)

    Østergaard, John Erland; Vadim, Lyssenko; Hvam, Jørn Märcher

    2001-01-01

    Optical coherent control experiments in semiconductors reveal how inhomogeneous broadening must be taken into account in contrast to previous coherent control experiments in atomic and molecular systems. With spectral resolution elf the coherent control signal, the optical phases involved...... is observed in the four-wave mixing spectra as a function of phase-delay representing coherent control in the spectral domain. The spectral phase change of this modulation provides a spectroscopic tool to analyze contributions of inhomogeneous broadening to electronic resonances in semiconductor structures....

  9. Doppler Shifts and Broadening and the Structure of the X-ray Emission from Algol

    CERN Document Server

    Chung, S M; Kashyap, V L; Lin, L W; Ratzlaff, P W; Chung, Sun Mi; Drake, Jeremy J.; Kashyap, Vinay L.; Lin, Li Wei; Ratzlaff, Peter W.

    2004-01-01

    In a study of Chandra High Energy Transmission Grating spectra of Algol, we clearly detect Doppler shifts caused by the orbital motion of Algol B. These data provide the first definitive proof that the X-ray emission of Algol is dominated by the secondary, in concordance with expectations that Algol A (B8) is X-ray dark. The measured Doppler shifts are slightly smaller than expected, implying an effective orbital radius of about 10 Rsolar, instead of 11.5 Rsolar for the Algol B center of mass. This could be caused by a small contribution of X-ray flux from Algol A (10-15%), possibly through accretion. The more likely explanation is an asymmetric corona biased toward the system center of mass by the tidal distortion of the surface of Algol B. Analysis of the strongest lines indicates excess line broadening of ~150 km/s above that expected from thermal motion and surface rotation. Possible explanations include turbulence, flows or explosive events, or rotational broadening from a radially extended corona. We fa...

  10. The STARS Alliance: Viable Strategies for Broadening Participation in Computing

    Science.gov (United States)

    Dahlberg, Teresa; Barnes, Tiffany; Buch, Kim; Rorrer, Audrey

    2011-01-01

    The Students and Technology in Academia, Research, and Service (STARS) Alliance is a nationally-connected system of regional partnerships among higher education, K-12 schools, industry and the community with a mission to broaden the participation of women, under-represented minorities and persons with disabilities in computing (BPC). Each regional…

  11. On the Fly Doppler Broadening Using Multipole Representation

    Energy Technology Data Exchange (ETDEWEB)

    Khassenov, Azamat; Choi, Sooyoung; Lee, Deokjung [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

    2015-05-15

    On the Fly Doppler broadening is the technique to avoid pre-generation of the microscopic cross section, in other words, reduce the amount of storage. Currently, there are different types of formalisms used by NJOY code to generate reaction cross section and accomplish its Doppler broadening. Single-Level Breit-Wigner (SLBW) formalism is limited to well-separated resonances, in other words, it does not consider interference between energy levels. Multi-Level Breit- Wigner formalism (MLBW) was tested as the candidate for the cross section generation in the Monte Carlo code, which is under development in UNIST. According to the results, MLBW method requires huge amount of computational time to produce cross section at certain energy point. Reich-Moore (RM) technique can generate only 0K cross section, which means that it cannot produce broaden cross section directly from resonance parameters. The first step was to convert resonance parameters given in nuclear data file into multipoles. MPR shows very high potential to be used as the formalism in the on-the-fly Doppler broadening module of MCS. One of the main reasons is that comparison of the time cost shown in Table IV supports application of multipole representation.

  12. Broadening the concept of international entrepreneurship: 'Consumers as international entrepreneurs'

    NARCIS (Netherlands)

    Y. Chandra; N. Coviello

    2010-01-01

    We integrate theories from international business, entrepreneurship, innovation, marketing and network economics to develop a four-part typology of ‘consumers as international entrepreneurs’. This broadens the concept of international entrepreneurship and complements the firm-level focus customary i

  13. Quality's Higher Education Dividends: Broadened Custodianship and Global Public Scholarship

    Science.gov (United States)

    Jacobs, Gerrie J.

    2010-01-01

    This paper speculates on the possible contribution of the quality movement to higher education and the perceived dividends received from this, in general, over the past two decades but also, more specifically, with reference to the author's institution in South Africa. The first major quality contribution is a gradual broadening of higher…

  14. On-The-Fly neutron Doppler broadening in MCNP

    International Nuclear Information System (INIS)

    Multi-physics calculations may involve coupling continuous-energy Monte Carlo neutronics codes to CFD codes that provide many thousands or even millions of region temperatures. The traditional Monte Carlo approach - using pre-calculated Doppler broadened nuclear cross-sections - is not feasible for these large multi-physics problems. Instead, an On-the-Fly (OTF) Doppler broadening methodology is required, whereby neutron cross-sections are broadened during the Monte Carlo transport. To this end, we have developed a methodology for MCNP to provide OTF broadening based on cell temperatures during neutron tracking. The method enables the use of many thousands or more temperatures in MCNP Monte Carlo calculations for multi-physics applications, significantly advancing the state-of-the-art by permitting the solution of problems that were not previously possible with continuous-energy Monte Carlo codes. A production library with an extended set of isotopes has been developed for use with MCNP6. Calculations of test problems with MCNP6 and the new library demonstrate the accuracy and effectiveness of the OTF approach. (authors)

  15. Peak broadening in paper chromatography and related techniques : III. Peak broadening in thin-layer chromatography on cellulose powder

    NARCIS (Netherlands)

    Ligny, C.L. de; Remijnse, A.G.

    1968-01-01

    The mechanism of peak broadening in thin-layer chromatography on cellulose powder was investigated by comparing the peak widths obtained in chromatography with those caused only by diffusion in the cellulose powder, for a set of amino acids of widely differing RF values and six kinds of cellulose po

  16. On systematic errors in spectral line parameters retrieved with the Voigt line profile

    Science.gov (United States)

    Kochanov, V. P.

    2012-08-01

    Systematic errors inherent in the Voigt line profile are analyzed. Molecular spectrum processing with the Voigt profile is shown to underestimate line intensities by 1-4%, with the errors in line positions being 0.0005 cm-1 and the decrease in pressure broadening coefficients varying from 5% to 55%.

  17. Resolution-enhancement of broadened spectra of the UV-light and thermal treated alanine free radicals

    International Nuclear Information System (INIS)

    Two methods for resolution-enhancing broadened spectra were analyzed. One method was used to treat ESR spectra of the γ-ray induced alanine free radicals and to study the effect when they are subjected to UV-light and heat. Spectral differences are obvious between these treatments. From a combined UV-light and heat treatment of these free radicals, some ESR lines disappear while five broad lines still remain. These spectral differences may clearly suggest the existence of two or more free radical species in γ-ray irradiated alanine that can be predicted at room temperature

  18. Suppression of power-broadening in strong-coupling photoassociation in the presence of a Feshbach resonance

    CERN Document Server

    Deb, Bimalendu

    2009-01-01

    Photoassociation (PA) spectrum in the presence of a magnetic Feshbach resonance is analyzed. Nonperturbative solution of the problem yields analytical expressions for PA linewidth and shift which are applicable for arbitrary PA laser intensity and magnetic field tuning of Feshbach Resonance. We show that by tuning magnetic field close to Fano minimum, it is possible to suppress power broadening at increased laser intensities. This occurs due to quantum interference of PA transitions from unperturbed and perturbed continuum. Line narrowing at high laser intensities is accompanied by large spectral shifts. We briefly discuss important consequences of line narrowing in cold collisions.

  19. Stability analysis for bad cavity lasers with inhomogeneously broadened gain

    CERN Document Server

    Kazakov, Georgy A

    2016-01-01

    Bad cavity lasers are experiencing renewed interest in the context of active optical frequency standards, due to their enhanced robustness against fluctuations of the laser cavity. The gain medium would consist of narrow-linewidth atoms, either trapped inside the cavity or intersecting the cavity mode dynamically. A finite velocity distribution, atomic interactions, or interactions of realistic multilevel atoms with external field leads to an inhomogeneous broadening of the atomic gain profile. This can bring the bad cavity laser to operate in unstable regimes characterized by complex temporal patterns of the field amplitude. We present a new and efficient method for the stability analysis of bad cavity lasers with inhomogeneously broadened gain. We apply this method to identify the steady-state solutions for the metrology-relevant case of spin-1/2 atoms interacting with an external magnetic field.

  20. Collisional broadening of angular correlations in a multiphase transport model

    CERN Document Server

    Edmonds, Terrence; Wang, Fuqiang

    2016-01-01

    Systematic comparisons of jetlike correlation data to radiative and collisional energy loss model calculations are essential to extract transport properties of the quark-gluon medium created in relativistic heavy ion collisions. This paper presents a transport study of collisional broadening of jetlike correlations, by following parton-parton collision history in a multiphase transport (AMPT) model. The correlation shape is studied as a function of the number of parton-parton collisions suffered by a high transverse momentum probe parton ($N_{\\rm coll}$) and the azimuth of the probe relative to the reaction plane ($\\phi_{\\rm fin.}^{\\rm probe}$). Correlation is found to broaden with increasing $N_{\\rm coll}$ and $\\phi_{\\rm fin.}^{\\rm probe}$ from in- to out-of-plane direction. This study provides a transport model benchmark for future jet-medium interaction studies.

  1. Positive emotions and the social broadening effects of Barack Obama.

    Science.gov (United States)

    Ong, Anthony D; Burrow, Anthony L; Fuller-Rowell, Thomas E

    2012-10-01

    Past experiments have demonstrated that the cognitive broadening produced by positive emotions may extend to social contexts. Building on this evidence, we hypothesized that positive emotions triggered by thinking about Barack Obama may broaden and expand people's sense of self to include others. Results from an expressive-writing study demonstrated that African American college students prompted to write about Obama immediately prior to and after the 2008 presidential election used more plural self-references, fewer other-references, and more social references. Mediation analyses revealed that writing about Obama increased positive emotions, which in turn increased the likelihood that people thought in terms of more-inclusive superordinate categories (we and us rather than they and them). Implications of these findings for the role of positive emotions in perspective-taking and intergroup relations are considered. PMID:22905966

  2. Positive emotions and the social broadening effects of Barack Obama.

    Science.gov (United States)

    Ong, Anthony D; Burrow, Anthony L; Fuller-Rowell, Thomas E

    2012-10-01

    Past experiments have demonstrated that the cognitive broadening produced by positive emotions may extend to social contexts. Building on this evidence, we hypothesized that positive emotions triggered by thinking about Barack Obama may broaden and expand people's sense of self to include others. Results from an expressive-writing study demonstrated that African American college students prompted to write about Obama immediately prior to and after the 2008 presidential election used more plural self-references, fewer other-references, and more social references. Mediation analyses revealed that writing about Obama increased positive emotions, which in turn increased the likelihood that people thought in terms of more-inclusive superordinate categories (we and us rather than they and them). Implications of these findings for the role of positive emotions in perspective-taking and intergroup relations are considered.

  3. On the process dependent nuclear $k_\\perp$ broadening effect

    OpenAIRE

    Schäfer, Andreas; Zhou, Jian

    2013-01-01

    We study the process dependent nuclear $k_\\perp$ broadening effect by employing the transverse momentum dependent(TMD) factorization approach in combination with the Mclerran-Venugopalan(MV) model. More specifically, we investigate how the parton transverse momentum distributions are affected by the process dependent gauge links in cold nuclear matter. In particular, our analysis also applies to the polarized cases including the nuclear quark Boer-Mulders function and the linearly polarized g...

  4. VAT Base Broadening, Self Supply, and The Informal Sector

    OpenAIRE

    John Piggott; John Whalley

    1998-01-01

    We develop a general equilibrium tax model to evaluate the impacts of equal yield base broadening in indirect taxes from high rate narrow based (typically manufactures) taxes to broad based taxes (including services) such as a VAT. We capture differences in choice of mode of supply between market goods, such as manufactures, which cannot be supplied other than through the market, and self-suppliable services and informal sector supplied products. Using this formulation, we are able to provide...

  5. Positive mood broadens visual attention to positive stimuli

    OpenAIRE

    Wadlinger, Heather A.; Isaacowitz, Derek M.

    2006-01-01

    In an attempt to investigate the impact of positive emotions on visual attention within the context of Fredrickson's (1998) broaden-and-build model, eye tracking was used in two studies to measure visual attentional preferences of college students (n=58, n=26) to emotional pictures. Half of each sample experienced induced positive mood immediately before viewing slides of three similarly-valenced images, in varying central-peripheral arrays. Attentional breadth was determined by measuring the...

  6. Momentum broadening in unstable quark-gluon plasma

    OpenAIRE

    Carrington, M. E.; Mrówczyński, St.; Schenke, B.

    2016-01-01

    Quark-gluon plasma produced at the early stage of ultrarelativistic heavy ion collisions is unstable, if weakly coupled, due to the anisotropy of its momentum distribution. Chromomagnetic fields are spontaneously generated and can reach magnitudes much exceeding typical values of the fields in equilibrated plasma. We consider a high energy test parton traversing an unstable plasma that is populated with strong fields. We study the momentum broadening parameter $\\hat q$ which determines the ra...

  7. Broadening the diagnosis of bipolar disorder: benefits vs. risks

    OpenAIRE

    Strakowski, Stephen M.; Fleck, David E.; MAJ, MARIO

    2011-01-01

    There is considerable debate over whether bipolar and related disorders that share common signs and symptoms, but are currently defined as distinct clinical entities in DSM-IV and ICD-10, may be better characterized as falling within a more broadly defined “bipolar spectrum”. With a spectrum view in mind, the possibility of broadening the diagnosis of bipolar disorder has been proposed. This paper discusses some of the rationale for an expanded diagnostic scheme from both cl...

  8. Dispersive hole growth kinetics and fluence broadening of the zero-phonon hole of impurities in amorphous hosts

    International Nuclear Information System (INIS)

    A detailed treatment of the relationship between the dispersive growth kinetics of the zero-phonon hole (ZPH) of an impurity molecule in an amorphous host and burn fluence broadening of the ZPH is presented. Focus is on non-photochemical hole burning (NPHB). The equation used for simulations accounts for dispersion due to a distribution of tunneling parameters (λ-distribution), the angle between the laser polarization and the transition dipole (α-distribution), and off-resonant absorption of the zero-phonon line (ω-distribution). Two cases are considered: burned laser linewidth narrow relative to the homogeneous width of the zero-phonon line; and the reverse situation. Results are presented for two model systems whose parameter values are similar to those of aluminum phthalocyanine tetrasulphonate (APT) in hyperquenched glassy water and in hyperquenched glassy ethanol. For comparison, results are presented for the case where the hole growth kinetics are non-dispersive (single-exponential). It is found that at the early stage of burning fluence broadening is considerably more severe for a dispersive system than for a non-dispersive system. A straightforward explanation for this is given. The results are compared with those of earlier works on dispersive hole growth kinetics and fluence broadening. The results reveal the types of experiment needed to understand the aforementioned relationship, a requirement for determination of the homogeneous width of the ZPH that reflects the dynamics of the system

  9. The rotational broadening of V395 Car - implications on compact object's mass

    CERN Document Server

    Shahbaz, T

    2007-01-01

    CONTEXT: The masses previously obtained for the X-ray binary 2S0921-630 inferred a compact object that was either a high-mass neutron star or low-mass black-hole, but used a previously published value for the rotational broadening (vsini) with large uncertainties. AIMS: We aim to determine an accurate mass for the compact object through an improved measurement of the secondary star's projected equatorial rotational velocity. METHODS: We have used UVES echelle spectroscopy to determine the vsini of the secondary star (V395 Car) in the low-mass X-ray binary 2S0921-630 by comparison to an artificially broadened spectral-type template star. In addition, we have also measured vsini from a single high signal-to-noise ratio absorption line profile calculated using the method of Least-Squares Deconvolution (LSD). RESULTS: We determine vsini to lie between 31.3+/-0.5km/s to 34.7+/-0.5km/s (assuming zero and continuum limb darkening, respectively) in disagreement with revious results based on intermediate resolution sp...

  10. High frequency VLBI observations of the scatter broadened quasar B2005+403

    CERN Document Server

    Gabanyi, K E; Britzen, S; Krichbaum, T P; Ros, E; Witzel, A; Zensus, J A

    2006-01-01

    The quasar B2005+403 located behind the Cygnus region, is a suitable object for studying the interplay between propagation effects, which are extrinsic to the source and source intrinsic variability. On the basis of VLBI experiments performed at 1.6, 5, 8, 15, 22, and 43GHz between 1992-2003 and parallel multi-frequency monitoring of the total flux density, we investigated the variability of total flux density and source structure. Below 8 GHz, the point-like VLBI source is affected by scatter-broadening of the turbulent interstellar medium, which is located along the line of sight and likely associated with the Cygnus region. We present and discuss the measured frequency dependence of the source size, which shows a power-law with slope of -1.91+/-0.05. From the measured scattering angle at 1GHz of 77.1+/-4.0mas a SM=0.43+/-0.04 m^{-20/3} kpc is derived, consistent with the general properties of the ISM in this direction. The decreasing effect of angular broadening towards higher frequencies allows to study t...

  11. Characterization of ion-irradiated ODS Fe–Cr alloys by doppler broadening spectroscopy using a positron beam

    Energy Technology Data Exchange (ETDEWEB)

    Parente, P.; Leguey, T. [Departamento de Física and IAAB, Universidad Carlos III de Madrid, 28911 Leganés (Spain); Castro, V. de, E-mail: vanessa.decastro@uc3m.es [Departamento de Física and IAAB, Universidad Carlos III de Madrid, 28911 Leganés (Spain); Gigl, T.; Reiner, M.; Hugenschmidt, C. [FRM II and Physics Department, Technische Universität München, 85747 Garching (Germany); Pareja, R. [Departamento de Física and IAAB, Universidad Carlos III de Madrid, 28911 Leganés (Spain)

    2015-09-15

    The damage profile of oxide dispersion strengthened steels after single-, or simultaneous triple-ion irradiation at different conditions has been characterized using a low energy positron beam in order to provide information on microstructural changes induced by irradiation. Doppler broadening and coincident Doppler broadening measurements of the positron annihilation line have been performed on different Fe–Cr–(W,Ti) alloys reinforced with Y{sub 2}O{sub 3}, to identify the nature and stability of irradiation-induced open-volume defects and their possible association with the oxide nanoparticles. It was found that irradiation induced vacancy clusters are associated with Cr atoms. The results are of highest interest for modeling the damage induced by 14 MeV neutrons in reduced activation Fe–Cr alloys relevant for fusion devices.

  12. Temperature dependences of N2-broadening and shift coefficients in the ν6 perpendicular band of 12CH3D

    International Nuclear Information System (INIS)

    The temperature-dependences of line broadening and shift parameters for many 12CH3D transitions have been determined using six high-resolution, high signal-to-noise ratio, room-temperature CH3D (98% purity) and CH3D-N2 spectra recorded with 25 cm path length ( at 0.01 cm−1 unapodized resolution) using the McMath−Pierce FTS located on Kitt Peak, Arizona, and 17 additional high quality, pure CH3D (99% purity) and CH3D-N2 spectra recorded between 79 and 296 K with the 20.38 cm path coolable cell (at 0.0056 cm−1 unapodized resolution) with the Bruker 125HR FTS at the Jet Propulsion Laboratory (JPL), Pasadena, California. The spectra have been fitted simultaneously applying a multispectrum nonlinear least-squares technique. In the analysis, the Lorentzian N2-broadened half-width coefficients and the corresponding pressure-shift coefficients as well as their temperature dependences are extracted for about 400 transitions (0≤J″≤19, K″≤16) in the perpendicular (ΔK=±1) ν6 band. At 296 K, the measured N2-broadened half-width coefficients range from 0.0209 to 0.0782 cm−1 atm−1 whereas the majority of the associated N2-induced shift coefficients are negative, and the values are between -0.016 and 0.005 cm−1 atm−1. The temperature dependence exponents for N2-broadened half-widths range between 0.264 and 0.924, whereas the temperature dependence coefficients for N2-induced shifts are between 0 and 0.00011 cm−1 atm−1 K−1. The N2-broadened half-width coefficients have been also calculated using a semi-classical approach based on a rigorous treatment of the active molecule as a symmetric top, a model intermolecular potential comprising both short- and long-range interactions, and exact classical trajectories. The role of the various high-order multipoles in the line-broadening at low, middle and high values of the rotational quantum number J″ has been investigated and the main features of the K-dependences analyzed. The calculations performed for

  13. On the Application of Stark Broadening Data Determined with a Semiclassical Perturbation Approach

    Directory of Open Access Journals (Sweden)

    Milan S. Dimitrijević

    2014-08-01

    Full Text Available The significance of Stark broadening data for problems in astrophysics, physics, as well as for technological plasmas is discussed and applications of Stark broadening parameters calculated using a semiclassical perturbation method are analyzed.

  14. Smile to see the forest: Facially expressed positive emotions broaden cognition

    OpenAIRE

    Johnson, Kareem J.; Waugh, Christian E.; Fredrickson, Barbara L.

    2010-01-01

    The broaden hypothesis, part of Fredrickson’s (1998, 2001) broaden-and-build theory, proposes that positive emotions lead to broadened cognitive states. Here, we present evidence that cognitive broadening can be produced by frequent facial expressions of positive emotion. Additionally, we present a novel method of using facial electromyography (EMG) to discriminate between Duchenne (genuine) and non-Duchenne (non-genuine) smiles. Across experiments, Duchenne smiles occurred more frequently du...

  15. A Doppler-broadening facility for positron spin relaxation (e{sup +}SR) experiments

    Energy Technology Data Exchange (ETDEWEB)

    Gessmann, Th.; Harmat, P.; Major, J.; Seeger, A. [Max-Planck-Institut fuer Metallforschung, Institut fuer Physik, Stuttgart, Stuttgart (Germany)

    1997-05-14

    A set-up is described for the determination of the spin polarization of positrons emitted from radioactive sources that makes use of the dependence of the Doppler broadening of the 511 keV annihilation photon line on the strength and direction (with regard to the spin polarization) of an applied magnetic field. In the so-called e{sup +}SR (positron spin relaxation) technique the sample to be investigated is part of the e{sup +}-spin polarimeter. Its application to the investigation of positronium formation in condensed matter is illustrated using crystalline quartz as an example. The method earlier applied to the positron annihilation in magnetized ferromagnets is now transferred to the detection of positronium (Ps) in condensed matter. This new approach makes use of the fact, that the ratio of Ps atoms in the singlet and the triplet states is larger in a magnetic field applied parallel to the positron-spin polarization than in an antiparallel field.

  16. Opacity broadening and interpretation of suprathermal CO linewidths: Macroscopic turbulence and tangled molecular clouds

    Science.gov (United States)

    Hacar, A.; Alves, J.; Burkert, A.; Goldsmith, P.

    2016-06-01

    Context. Since their first detection in the interestellar medium, (sub-)millimeter line observations of different CO isotopic variants have routinely been employed to characterize the kinematic properties of the gas in molecular clouds. Many of these lines exhibit broad linewidths that greatly exceed the thermal broadening expected for the low temperatures found within these objects. These observed suprathermal CO linewidths are assumed to originate from unresolved supersonic motions inside clouds. Aims: The lowest rotational J transitions of some of the most abundant CO isotopologues, 12CO and 13CO, are found to present large optical depths. In addition to well-known line saturation effects, these large opacities present a non-negligible contribution to their observed linewidths. Typically overlooked in the literature, in this paper we aim to quantify the impact of these opacity broadening effects on the current interpretation of the CO suprathermal line profiles. Methods: Combining large-scale observations and LTE modeling of the ground J = 1-0 transitions of the main 12CO, 13CO, C18O isotopologues, we have investigated the correlation of the observed linewidths as a function of the line opacity in different regions of the Taurus molecular cloud. Results: Without any additional contributions to the gas velocity field, a large fraction of the apparently supersonic (ℳ ~ 2-3) linewidths measured in both 12CO and 13CO (J = 1-0) lines can be explained by the saturation of their corresponding sonic-like, optically thin C18O counterparts assuming standard isotopic fractionation. Combined with the presence of multiple components detected in some of our C18O spectra, these opacity effects also seem to be responsible for most of the highly supersonic linewidths (ℳ > 8-10) detected in some of the broadest 12CO and 13CO spectra in Taurus. Conclusions: Our results demonstrate that most of the suprathermal 12CO and 13CO linewidths reported in nearby clouds like Taurus

  17. Auger Recombination in Self-Assembled Quantum Dots: Quenching and Broadening of the Charged Exciton Transition.

    Science.gov (United States)

    Kurzmann, Annika; Ludwig, Arne; Wieck, Andreas D; Lorke, Axel; Geller, Martin

    2016-05-11

    In quantum dots (QDs), the Auger recombination is a nonradiative process in which the electron-hole recombination energy is transferred to an additional carrier. It has been studied mostly in colloidal QDs, where the Auger recombination time is in the picosecond range and efficiently quenches the light emission. In self-assembled QDs, on the other hand, the influence of Auger recombination on the optical properties is in general neglected, assuming that it is masked by other processes such as spin and charge fluctuations. Here, we use time-resolved resonance fluorescence to analyze the Auger recombination and its influence on the optical properties of a single self-assembled QD. From excitation-power-dependent measurements, we find a long Auger recombination time of about 500 ns and a quenching of the trion transition by about 80%. Furthermore, we observe a broadening of the trion transition line width by up to a factor of 2. With a model based on rate equations, we are able to identify the interplay between tunneling and Auger rate as the underlying mechanism for the reduced intensity and the broadening of the line width. This demonstrates that self-assembled QDs can serve as an ideal model system to study how the charge recapture process, given by the band-structure surrounding the confined carriers, influences the Auger process. Our findings are not only relevant for improving the emission properties of colloidal QD-based emitters and dyes, which have recently entered the consumer market, but also of interest for more visionary applications, such as quantum information technologies, based on self-assembled quantum dots. PMID:27087053

  18. Auger Recombination in Self-Assembled Quantum Dots: Quenching and Broadening of the Charged Exciton Transition.

    Science.gov (United States)

    Kurzmann, Annika; Ludwig, Arne; Wieck, Andreas D; Lorke, Axel; Geller, Martin

    2016-05-11

    In quantum dots (QDs), the Auger recombination is a nonradiative process in which the electron-hole recombination energy is transferred to an additional carrier. It has been studied mostly in colloidal QDs, where the Auger recombination time is in the picosecond range and efficiently quenches the light emission. In self-assembled QDs, on the other hand, the influence of Auger recombination on the optical properties is in general neglected, assuming that it is masked by other processes such as spin and charge fluctuations. Here, we use time-resolved resonance fluorescence to analyze the Auger recombination and its influence on the optical properties of a single self-assembled QD. From excitation-power-dependent measurements, we find a long Auger recombination time of about 500 ns and a quenching of the trion transition by about 80%. Furthermore, we observe a broadening of the trion transition line width by up to a factor of 2. With a model based on rate equations, we are able to identify the interplay between tunneling and Auger rate as the underlying mechanism for the reduced intensity and the broadening of the line width. This demonstrates that self-assembled QDs can serve as an ideal model system to study how the charge recapture process, given by the band-structure surrounding the confined carriers, influences the Auger process. Our findings are not only relevant for improving the emission properties of colloidal QD-based emitters and dyes, which have recently entered the consumer market, but also of interest for more visionary applications, such as quantum information technologies, based on self-assembled quantum dots.

  19. Strategies for broadening public involvement in space developments

    Science.gov (United States)

    Harris, Philip R.

    1992-01-01

    There is widespread public interest in and goodwill toward the space program. For NASA's plans for the next 25 years to be achieved, this public reservoir of support needs to be tapped and channeled. NASA endeavors have to reach out beyond the scientific, technological, and aerospace communities to foster wider participation in space exploration and exploitation. To broaden NASA support and spread out the financing of space activities, recommendations for consideration are offered in the area of economics, political, institutional, international, and managerial areas.

  20. Anomalous excitation facilitation in inhomogeneously broadened Rydberg gases

    CERN Document Server

    Letscher, Fabian; Niederprüm, Thomas; Ott, Herwig; Fleischhauer, Michael

    2016-01-01

    When atomic gases are laser driven to Rydberg states in an off resonant way, a single Rydberg atom may enhance the excitation rate of surrounding atoms. This leads to a facilitated excitation referred to as Rydberg anti-blockade. In the usual facilitation scenario, the detuning of the laser from resonance compensates the interaction shift. Here, we discuss a different excitation mechanism, which we call anomalous facilitation. This occurs on the "wrong side" of the resonance and originates from inhomogeneous broadening. The anomalous facilitation may be seen in experiments of attractively interacting atoms on the blue detuned side, where facilitation is not expected to appear.

  1. Theoretical Manifestation of the Broadening Effect on Photoelectron Angular Distributions

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jing-Tao(张敬涛); ZHOU Lan(周岚); ZHANG Wen-Qi(张文琦); XU Zhi-Zhan(徐至展); GUO Dong-Sheng(郭东升); R.R.Freeman

    2003-01-01

    The broadening effect in photoelectron angular distributions (PADs) observed by Freeman et al. Is studied theoretically. Using a nonperturbative scattering theory developed for multiphoton ionization with the inclusion of spontaneous emission, we calculate the PADs for above-threshold ionization (ATI) peaks. The numerical calculations from our theory reproduce the kinetic-energy dependence and the laser-intensity dependence of PADs of ATI peaks observed by Freeman et al., [Phys. Rev. Lett. 57 (1986) 3156] and provide an evidence for the existence of the ponderomotive momentum of intense laser fields.

  2. Pressure broadening of the ((dt. mu. )dee)* formation resonances

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, J.S.; Leon, M.; Padial, N.T.

    1988-12-27

    The treatment of ((dt..mu..)dee)* formation at high densities as a pressure broadening process is discussed. Cross sections for collisions of the complex (dt..mu..)dee, and of the D/sub 2/ molecule from which it is formed, with the bath molecules have been accurately calculated. These cross sections are used to calculate the collisional width in three variations of the impact approximation that have been proposed for this problem. In general, the quasistatic approximation is shown to satisfy the usual conditions of muon-catalyzed fusion better than does the impact approximation. A preliminary rough treatment is presented to illustrate the quasistatic approximation.

  3. Stark Widths of Spectral Lines of Neutral Neon

    Indian Academy of Sciences (India)

    Milan S. Dimitrijević; Zoran Simić; Andjelka Kovačević; Aleksandar Valjarević; Sylvie Sahal-Bréchot

    2015-12-01

    In order to complete Stark broadening data for Ne I spectral lines which are needed for analysis of stellar atmospheres, collisional widths and shifts (the so-called Stark broadening parameters) of 29 isolated spectral lines of neutral neon have been determined within the impact semiclassical perturbation method. Calculations have been performed for the broadening by collisions with electrons, protons and ionized helium for astrophysical applications, and for collisions with ionized neon and argon for laboratory plasma diagnostics. The shifts have been compared with existing experimental values. The obtained data will be included in the STARK-B database, which is a part of the Virtual Atomic and Molecular Data Center – VAMDC.

  4. Linking the thermodynamic temperature to an optical frequency: recent advances in Doppler broadening thermometry

    Science.gov (United States)

    2016-01-01

    Laser spectroscopy in the linear regime of radiation–matter interaction is a powerful tool for measuring thermodynamic quantities in a gas at thermodynamic equilibrium. In particular, the Doppler effect can be considered a gift of nature, linking the thermal energy to an optical frequency, namely the line centre frequency of an atomic or molecular spectral line. This is the basis of a relatively new method of primary gas thermometry, known as Doppler broadening thermometry (DBT). This paper reports on the efforts that have been carried out, in the last decade, worldwide, to the end of making DBT competitive with more consolidated and accurate methodologies, such as acoustic gas thermometry and dielectric constant gas thermometry. The main requirements for low-uncertainty DBT, of both theoretical and technical nature, will be discussed, with a special focus on those related to the line shape model and to the frequency scale. A deep comparison among the different molecules that have been selected in successful DBT implementations is also reported. Finally, for the first time, to the best of my knowledge, the influence of refractive index effects is discussed. PMID:26903093

  5. Linking the thermodynamic temperature to an optical frequency: recent advances in Doppler broadening thermometry.

    Science.gov (United States)

    Gianfrani, Livio

    2016-03-28

    Laser spectroscopy in the linear regime of radiation-matter interaction is a powerful tool for measuring thermodynamic quantities in a gas at thermodynamic equilibrium. In particular, the Doppler effect can be considered a gift of nature, linking the thermal energy to an optical frequency, namely the line centre frequency of an atomic or molecular spectral line. This is the basis of a relatively new method of primary gas thermometry, known as Doppler broadening thermometry (DBT). This paper reports on the efforts that have been carried out, in the last decade, worldwide, to the end of making DBT competitive with more consolidated and accurate methodologies, such as acoustic gas thermometry and dielectric constant gas thermometry. The main requirements for low-uncertainty DBT, of both theoretical and technical nature, will be discussed, with a special focus on those related to the line shape model and to the frequency scale. A deep comparison among the different molecules that have been selected in successful DBT implementations is also reported. Finally, for the first time, to the best of my knowledge, the influence of refractive index effects is discussed. PMID:26903093

  6. Multiple scattering and $p_t$-broadening at RHIC energies

    CERN Document Server

    Papp, G; Fái, G; Lévai, Peter; Zhang, Y

    2002-01-01

    In ultrarelativistic heavy-ion collisions, in the 2 GeV$broadening of the expected hadronic (e.g. pion) $p_\\perp$ spectra relative to proton-proton ($pp$) collisions. Thus, higher transverse-momentum regions are populated than in $pp$ collisions. In a perturbative QCD based calculation we include the intrinsic transverse momentum ($k_\\perp$) of the partons in the nucleon (determined from $pp$ collisions), augmented by the extra broadening obtained via a systematic analysis of proton-nucleus ($pA$) collisions in the energy range 17$<\\sqrt{s}<$ 39 AGeV. The original polynomial spectra are modified, and a nearly exponential spectrum appears in the region 2$\\lesssim p_\\perp\\lesssim 3.5$ GeV. At present RHIC energies ($\\sqrt{s}=$130 AGeV), the slope of the calculated spectra is reminiscent of that of fluid-dynamical descriptions, but lacks any thermal ori...

  7. Improving Program Design and Assessment with Broadening Participation Resources

    Science.gov (United States)

    Siegfried, D.; Johnson, A.; Thomas, S. H.; Fauver, A.; Detrick, L.

    2012-12-01

    Many theoretical and research-based approaches suggest how to best use mentoring to enhance an undergraduate research program. The Institute for Broadening Participation's Pathways to Engineering and Pathways to Ocean Sciences projects synthesized a set of mentoring studies, theoretical sources, and other texts pertinent to undergraduate research program design into a suite of practical tools that includes an online mentoring manual, an online reference library of mentoring and diversity literature, and practical guides such as Using Social Media to Build Diversity in Your REU. The overall goal is to provide easy-to-access resources that can assist faculty and program directors in implementing or honing the mentoring elements in their research programs for undergraduates. IBP's Online Mentoring Manual addresses common themes, such as modeling, student self-efficacy, career development, retention and evaluation. The Online Diversity Reference Library provides a comprehensive, annotated selection of key policy documents, research studies, intervention studies, and other texts on broadening participation in science, technology, engineering and mathematics. IBP's suite of tools provides the theoretical underpinnings and research findings that can help leaders in education integrate site-appropriate mentoring elements into their educational programs. Program directors and faculty from a variety of program types and disciplines have benefitted from using the Manual and other resources. IBP continues the work of translating and synthesizing theory to practice and welcomes your participation and partnership in that effort.

  8. Broadening the diagnosis of bipolar disorder: benefits vs. risks

    Science.gov (United States)

    STRAKOWSKI, STEPHEN M.; FLECK, DAVID E.; MAJ, MARIO

    2011-01-01

    There is considerable debate over whether bipolar and related disorders that share common signs and symptoms, but are currently defined as distinct clinical entities in DSM-IV and ICD-10, may be better characterized as falling within a more broadly defined “bipolar spectrum”. With a spectrum view in mind, the possibility of broadening the diagnosis of bipolar disorder has been proposed. This paper discusses some of the rationale for an expanded diagnostic scheme from both clinical and research perspectives in light of potential drawbacks. The ultimate goal of broadening the diagnosis of bipolar disorder is to help identify a common etiopathogenesis for these conditions to better guide treatment. To help achieve this goal, bipolar researchers have increasingly expanded their patient populations to identify objective biological or endophenotypic markers that transcend phenomenological observation. Although this approach has and will likely continue to produce beneficial results, the upcoming DSM-IV and ICD-10 revisions will place increasing scrutiny on psychiatry’s diagnostic classification systems and pressure to re-evaluate our conceptions of bipolar disorder. However, until research findings can provide consistent and converging evidence as to the validity of a broader diagnostic conception, clinical expansion to a dimensional bipolar spectrum should be considered with caution. PMID:21991268

  9. N2 and O2 pressure broadening and pressure shift in the 4ν2 band of 16O12C32S

    Science.gov (United States)

    Galalou, S.; Ben Mabrouk, K.; Aroui, H.; Kwabia Tchana, F.; Willaert, F.; Flaud, J.-M.

    2011-12-01

    To measure accurately OCS concentrations in planetary atmospheres, it is important to know precisely nitrogen and oxygen pressure broadening and pressure-induced shift coefficients for the lines used in the retrievals. We present in this study the corresponding coefficients for lines of the P and R branches of the 4ν2 band of the primary isotopologue of carbonyl sulfide (16O12C32S).For this purpose, infrared absorption spectra of a natural carbonyl sulfide (OCS) gas sample were recorded at an unapodized resolution of 0.004 cm-1, at room temperature for different pressures of N2 and O2, using a Bruker IFS125HR spectrometer at the LISA Laboratory in France. The line parameters were derived using the multispectrum fitting method applied to the measured shapes of the lines, including the interference effects caused by the line overlaps.The results are compared with earlier measurements and with values calculated using a semi-classical model based upon the Robert and Bonamy formalism that reproduces rather well the experimental m (m=-J for P(J) lines and m=J+1 for R(J) lines) quantum number dependence of the N2 and O2 broadening coefficients. On the other hand most of the lines studied here have positive shift coefficients, which do not show any systematic dependence on m. However, in previous studies of the ν3, 2ν3 and ν2 bands, these coefficients were negative for all lines.

  10. Optical properties of an inhomogeneously broadened multilevel V-system in the weak and strong probe regimes

    CERN Document Server

    Kaur, Paramjit; Wasan, Ajay

    2015-01-01

    We present a theoretical model, using density matrix approach, to study the effect of weak as well as strong probe field on the optical properties of an inhomogeneously broadened multilevel V-system of the $^{87}$Rb D2 line. We consider the case of stationary as well as moving atoms and perform thermal averaging at room temperature. The presence of multiple excited states results in asymmetric absorption and dispersion profiles. In the weak probe regime, we observe the partial transparency window due to the constructive interference occurs between transition pathways at the line center. In a room temperature vapour, we obtain an increased linewidth of the transparency window and steep positive dispersion. For a strong probe regime, the transparency window with normal dispersion switches to enhanced absorption with anomalous dispersion at the line center. Here, we show how the electromagnetically induced transparency (EIT) depends on the polarizations of the applied fields. We also discuss the transient behavi...

  11. Phonon Properties of Materials from Neutron Resonance Doppler Broadening Measurements

    Science.gov (United States)

    Eric Lynn, J.

    2002-12-01

    At low temperatures the Doppler broadened widths of neutron resonances are strongly affected by the phonon characteristics of the material used for making the cross-section measurement. The Doppler width can be expressed in terms of the moments of the phonon spectrum carried by the atomic species with the resonant cross-section. Cross-section measurements made with tungsten and tantalum metals are reviewed here and compared with phonon information obtained by other methods. Applications of the method to a plutonium-gallium alloy and to some lanthanum barium cuprates are described briefly. We discuss possible extensions of the technique and how an epithermal flight path at the SNS may be advantageous.

  12. Coincidence Doppler Broadening of Positron Annihilation Radiation in Fe

    Science.gov (United States)

    do Nascimento, E.; Vanin, V. R.; Maidana, N. L.; Helene, O.

    2013-06-01

    We measured the Doppler broadening annihilation radiation spectrum in Fe, using 22NaCl as a positron source, and two Ge detectors in coincidence arrangement. The two-dimensional coincidence energy spectrum was fitted using a model function that included positron annihilation with the conduction band and 3d electrons, 3s and 3p electrons, and in-flight positron annihilation. Detectors response functions included backscattering and a combination of Compton and pulse pileup, ballistic deficit and shaping effects. The core electrons annihilation intensity was measured as 16.4(3) %, with almost all the remainder assigned to the less bound electrons. The obtained results are in agreement with published theoretical values.

  13. Brillouin resonance broadening due to structural variations in nanoscale waveguides

    CERN Document Server

    Wolff, Christian; Steel, Michael J; Eggleton, Benjamin J; Poulton, Christopher G

    2015-01-01

    We study the impact of structural variations (that is slowly varying geometry aberrations and internal strain fields) on the resonance width and shape of stimulated Brillouin scattering (SBS) in nanoscale waveguides. We find that they lead to an inhomogeneous resonance broadening through two distinct mechanisms: firstly, the acoustic frequency is directly influenced via mechanical nonlinearities; secondly, the optical wave numbers are influenced via the opto-mechanical nonlinearity leading to an additional acoustic frequency shift via the phase-matching condition. We find that this second mechanism is proportional to the opto-mechanical coupling and, hence, related to the SBS-gain itself. It is absent in intra-mode forward SBS, while it plays a significant role in backward scattering. In backward SBS increasing the opto-acoustic overlap beyond a threshold defined by the fabrication tolerances will therefore no longer yield the expected quadratic increase in overall Stokes amplification. Our results can be tra...

  14. Broadening soybean genetic basis in the northeast of China

    Institute of Scientific and Technical Information of China (English)

    WangJinling

    1994-01-01

    The bottle neek of advancement of soybean breeding inthe Northeast of China is the lack of genetic diversity of the parents used in cross breeding.In order to overcome this constrained condition,under the sponsorship of China National Committe of Natural Science Fundation,a network project with the topic"Broadening and Improving of the Genetic Basis of the Northeast Soybeans" was established in 1990,and the Northeast agricultural University was apointed to take charge of the project.The project included the following four items:I.Breeding high yield and improved quality Northeast Soybeans,directed by Hcilongjiang Academy of Agricultural Sciencee .II.Development of new soybean gerplasms highly resistant to diseases epidemic in Northeast China directed by Northeast Agricultural University.Ⅲ.Exploitation of the potential of wild and semicultivated soybeans for broadening and improving the genetic basis of Northeast soybeans,directed by Jilin Academy of Agricultural Science.Ⅳ.Improving methods and technique for development of new soybean genetic resources.directed by Nanjing Agricultural University .Each item contained several research subjects conducted by research workers of different institutes of agricultural sicences.During the period 1991-1992.considerable promising new germplasms had been discovered or developed.The new germplasms not only possessed specific improved characters but also behaved with appropriate ecological types adapted to different conditions of Northeast.Among the numerous new germplasms developed.Gong Jio 8757-3 had a protein content of 49.41%,100 seed weight 16-17g,and acceptable agronomic characters,which was considered a very valuable new high protein content germplasm.Such developed new germplasma with enforced and imprved genetic basis will be used primarily as parents in soybean cross breeding.

  15. The rotational broadening and the mass of the donor star of GRS 1915+105

    CERN Document Server

    Harlaftis, E T

    2004-01-01

    The binary parameters of the microquasar GRS 1915+105 have been determined by the detection of Doppler-shifted 12CO and 13CO lines in its K-band spectrum (Greiner et al., 2001, Nature, 414, 522). Here, we present further analysis of the same K-band VLT spectra and we derive a rotational broadening of the donor star of V sin i=26+-3 km/s from the 12CO/13CO lines. Assuming that the K-type star is tidally locked to the black hole and is filling its Roche-lobe surface, then the implied mass ratio is q = M_d/M_x = 0.058+-0.033. This result, combined with (P, K, i)=(33.5 d, 140 km/s, 66 deg) gives a more refined mass estimate for the black hole, $M_x=14.0+-4.4 M_{\\odot}$, than previously estimated, using an inclination of i=66+-2 deg (Fender et al. 1999) as derived from the orientation of the radio jets and a more accurate distance. The mass for the early K-type giant star is $M_d=0.81\\pm0.53 M_{\\odot}$, consistent with a more evolved stripped-giant donor star in GRS 1915+105 than, for example, the donor star of th...

  16. Broadening of nuclear engineering programs: An engineering physics approach at Rensselaer

    International Nuclear Information System (INIS)

    With the maturing of nuclear engineering as an academic discipline and the uncertainty surrounding the nuclear industry, attention is being increasingly turned to ways in which the base of traditional nuclear engineering programs in universities can be broadened to make them more attractively useful to a wider class of potential students and employers while maintaining the strengths in mainstream areas of nuclear technology. An approach that seems to provide a natural evolution combining the existing programmatic strengths, infrastructure, and resources with the trending needs of a broad segment of diversified industries is the development and initiation of an engineering physics degree program as an adjunct to an established nuclear engineering curriculum. In line with these developments, a new comprehensive academic program offering baccalaureate, master's, and doctoral degrees in engineering physics has been developed and formally instituted at Rensselaer Polytechnic Institute (RPI). It provides a valuable opportunity for students to pursue education and research that cuts across traditional disciplinary lines, leading to a wide variety of career opportunities in industry, government, national research and defense laboratories, and academia

  17. Line shape modeling in warm and dense hydrogen plasmas

    Science.gov (United States)

    Ferri, S.; Calisti, A.; Mossé, C.; Talin, B.; Gigosos, M. A.; González, M. A.

    2007-05-01

    A study of hydrogen lines emitted in warm ( T˜1eV) and dense ( N≥1018cm -3) plasmas is presented. Under such plasma conditions, the electronic and the ionic contributions to the line width are comparable, and the general question related to a transition from impact to quasi-static broadening arises not only for the far wings but also for the core of spectral lines. The transition from impact to quasi-static broadening for electrons is analyzed by means of Frequency Fluctuation Model (FFM). In parallel, direct integration of the semi-classical evolution equation is performed using electron electric fields calculated by Molecular Dynamics (MD) simulations that permit one to correctly describe the emitter environment. New cross comparisons between benchmark MD simulations and FFM are carried out for electron broadening of the Balmer series lines, and, especially, for the Hα line, for which a few experiments in the warm and dense plasma regimes are available.

  18. Measurements of pressure induced self-broadening and frequency shift coefficients of methane R9 manifold of 2v3 band

    Institute of Scientific and Technical Information of China (English)

    Weiguang Ma; Lei Dong; Wangbao Yin; Linfeng Li; Lei Zhang; Suotang Jia

    2005-01-01

    @@ An external-cavity diode laser (ECDL) has been used to investigate pressure-induced self-broadening as well as frequency shift of 2v3 band R9 manifold of methane. A phase sensitivity detection technology has been employed to determine the pressure induced frequency shift coefficient, however, which is obtained by line shape analyses of the recorded absorption spectrum. F1 and F2 unresolved double lines near 6105.626 cm-1 were measured as an object because they are often used to the high sensitivity detection of trace methane. The results show that the self-broadening and pressure induced frequency shift coefficients are 0.0232±0.003 and 0.0055±0.0007 MHz/Pa, respectively.

  19. Opacity Broadening of $^{13}$CO Linewidths and its Effect on the Variance-Sonic Mach Number Relation

    CERN Document Server

    Correia, Caio; Lazarian, Alex; Ossenkopf, Volker; Stutzki, Jürgen; Kainulainen, Jouni; Kowal, Grzegorz; de Medeiros, José Renan

    2014-01-01

    We study how the estimation of the sonic Mach number ($M_s$) from $^{13}$CO linewidths relates to the actual 3D sonic Mach number. For this purpose we analyze MHD simulations which include post-processing to take radiative transfer effects into account. As expected, we find very good agreement between the linewidth estimated sonic Mach number and the actual sonic Mach number of the simulations for optically thin tracers. However, we find that opacity broadening causes $M_s$ to be overestimated by a factor of ~ 1.16 - 1.3 when calculated from optically thick $^{13}$CO lines. We also find that there is a dependency on the magnetic field: super-Alfv\\'enic turbulence shows increased line broadening as compared with sub-Alfv\\'enic turbulence for all values of optical depth for supersonic turbulence. Our results have implications for the observationally derived sonic Mach number--density standard deviation ($\\sigma_{\\rho/}$) relationship, $\\sigma^2_{\\rho/}=b^2M_s^2$, and the related column density standard deviatio...

  20. Broadening the Participation of Native Americans in Earth Science

    Science.gov (United States)

    Bueno Watts, Nievita

    Climate change is not a thing of the future. Indigenous people are being affected by climate changes now. Native American Earth scientists could help Native communities deal with both climate change and environmental pollution issues, but are noticeably lacking in Earth Science degree programs. The Earth Sciences produce the lowest percentage of minority scientists when compared with other science and engineering fields. Twenty semi-structured interviews were gathered from American Indian/ Alaska Native Earth Scientists and program directors who work directly with Native students to broaden participation in the field. Data was analyzed using qualitative methods and constant comparison analysis. Barriers Native students faced in this field are discussed, as well as supports which go the furthest in assisting achievement of higher education goals. Program directors give insight into building pathways and programs to encourage Native student participation and success in Earth Science degree programs. Factors which impede obtaining a college degree include financial barriers, pressures from familial obligations, and health issues. Factors which impede the decision to study Earth Science include unfamiliarity with geoscience as a field of study and career choice, the uninviting nature of Earth Science as a profession, and curriculum that is irrelevant to the practical needs of Native communities or courses which are inaccessible geographically. Factors which impede progress that are embedded in Earth Science programs include educational preparation, academic information and counseling and the prevalence of a Western scientific perspective to the exclusion of all other perspectives. Intradepartmental relationships also pose barriers to the success of some students, particularly those who are non-traditional students (53%) or women (80%). Factors which support degree completion include financial assistance, mentors and mentoring, and research experiences. Earth scientists

  1. Phase Memory Control in an Inhomogeneously Broadened Ensemble of Three-Level Systems and Stimulated Photon Echo FormationPlease check captured article title, if appropriate.-->

    Science.gov (United States)

    Nefediev, L. A.; Garnaeva, G. I.; Nizamova, E. I.

    2016-09-01

    Phase memory in a three-level system that is associated with the correspondence of isochromates of inhomogeneously broadened lines excited by lasers at various resonant frequencies with a common energy level in different time intervals is studied. It is shown that external spatially inhomogeneous electric fields can control such phase memory and could be used to determine the optimum conditions for forming a stimulated photon echo in a threelevel system.

  2. A temporally and spatially resolved electron density diagnostic method for the edge plasma based on Stark broadening

    Science.gov (United States)

    Zafar, A.; Martin, E. H.; Shannon, S. C.; Isler, R. C.; Caughman, J. B. O.

    2016-11-01

    An electron density diagnostic (≥1010 cm-3) capable of high temporal (ms) and spatial (mm) resolution is currently under development at Oak Ridge National Laboratory. The diagnostic is based on measuring the Stark broadened, Doppler-free spectral line profile of the n = 6-2 hydrogen Balmer series transition. The profile is then fit to a fully quantum mechanical model including the appropriate electric and magnetic field operators. The quasi-static approach used to calculate the Doppler-free spectral line profile is outlined here and the results from the model are presented for H-δ spectra for electron densities of 1010-1013 cm-3. The profile shows complex behavior due to the interaction between the magnetic substates of the atom.

  3. Hyperfine structure effects in Doppler-broadening thermometry on water vapor at 1.4 μm

    Science.gov (United States)

    Domenica De Vizia, Maria; Odintsova, Tatyana; Gianfrani, Livio

    2016-04-01

    This article builds upon a previous work dealing with the budget of uncertainties associated to our recent determination of the Boltzmann constant by means of Doppler broadening thermometry. We report on the outcomes of theoretical calculations and numerical simulations aimed to precisely quantify the influence of the unresolved hyperfine structure of a given ortho component of the \\text{H}218 O spectrum at 1.4 μm on the measurement of the Doppler width of the line itself. We have found that, if the hyperfine structure of the {{4}4,1}\\to {{4}4,0} line of the {ν1}+{ν3} band was ignored, the spectroscopic measurement of the Boltzmann constant would be affected by a relative systematical deviation of 4\\cdot {{10}-8} .

  4. Gamma-ray line transients

    International Nuclear Information System (INIS)

    Early interpretations of the variability of the narrow 0.511 MeV annihilation line from the Galactic center (GC) were confused by the unrecognized presence of a very extended component (mid 70s-mid 80s). Transient behavior was suggested by comparisons of measurements made by instruments with comparable fields of view, and by detection of other lines which could be interpreted as broadened and Doppler-shifted versions of the line. A new generation of instruments (late 80s-early 90s) provided more compelling evidence, by improved imaging capability (identifying a known transient high-energy candidate source, 1E 1740.7-2942), and by improved sensitivity. Additional broadened, shifted, and Compton-scattered derivatives of the annihilation line were detected from this and other sources. At the same time, theoretical developments suggested exciting new physics which might arise in the accretion regimes around black holes, of which these features would be important diagnostics. In the GRO era the existence of such transient lines has been brought into question by the failure of long-term monitoring to detect them. A seemingly critical observation of the GC by three different instruments simultaneously, in which transient emission was detected only by one, provides the strongest evidence that the earlier results were in error. Recent developments in accretion disk theory have weakened the theoretical case for the lines. I draw conclusions concerning the nature of scientific inquiry and public outreach efforts in science

  5. Broadening Participation: Mentoring Community College Students in a Geoscience REU

    Science.gov (United States)

    Smith, M.; Osborn, J.

    2015-12-01

    Increasingly, REUs are recruiting from community colleges as a means of broadening participation of underrepresented minorities, women, and low-income students in STEM. As inclusion of community college students becomes normalized, defining the role of science faculty and preparing them to serve as mentors to community college students is a key component of well-designed programs. This session will present empirical research regarding faculty mentoring in the first two years of an NSF-REU grant to support community college students in a university's earth and environmental science labs. Given the documented benefits of undergraduate research on students' integration into the scientific community and their career trajectory in STEM, the focus of the investigation has been on the processes and impact of mentoring community college STEM researchers at a university serving a more traditionally privileged population; the degree to which the mentoring relationships have addressed community college students needs including their emotional, cultural and resource needs; and gaps in mentor training and the mentoring relationship identified by mentors and students.

  6. Momentum broadening in unstable quark-gluon plasma

    CERN Document Server

    Carrington, M E; Schenke, B

    2016-01-01

    Quark-gluon plasma produced at the early stage of ultrarelativistic heavy ion collisions is unstable, if weakly coupled, due to the anisotropy of its momentum distribution. Chromomagnetic fields are spontaneously generated and can reach magnitudes much exceeding typical values of the fields in equilibrated plasma. We consider a high energy test parton traversing an unstable plasma that is populated with strong fields. We study the momentum broadening parameter $\\hat q$ which determines the radiative energy loss of the test parton. We develop a formalism which gives $\\hat q$ as the solution of an initial value problem, and we focus on extremely oblate plasmas which are physically relevant for relativistic heavy ion collisions. The parameter $\\hat q$ is found to be strongly dependent on time. For short times it is of the order of the equilibrium value, but at later times $\\hat q$ grows exponentially due to the interaction of the test parton with unstable modes and becomes much bigger than the value in equilibri...

  7. Mass transfer kinetics, band broadening and column efficiency.

    Science.gov (United States)

    Gritti, Fabrice; Guiochon, Georges

    2012-01-20

    Important progress was recently made in our understanding of the physico-chemical aspects of mass transfer kinetics in chromatographic columns, in methods used for accurate determination of the different contributions to the height equivalent to a theoretical plate (HETP), and in the application of these advances to the elucidation of mass transfer mechanisms in columns packed with recent chromatographic supports (sub-2 μm fully porous particles, sub-3 μm core-shell particles, and monoliths). The independent contributions to the HETP are longitudinal diffusion, eddy dispersion, liquid-solid mass transfer (including trans-particle or trans-skeleton mass transfer and external film mass transfer), and the contributions caused by the thermal heterogeneity of the column. The origin and importance of these contributions are investigated in depth. This work underlines the areas in which improvements are needed, an understanding of the contribution of the external film mass transfer term, a better design of HPLC instruments providing a decrease of the extra-column band broadening contributions to the apparent HETP, the development of better packing procedures giving more radially homogeneous column beds, and new packing materials having a higher thermal conductivity to eliminate the nefarious impact of heat effects in very high pressure liquid chromatography (vHPLC) and supercritical fluid chromatography (SFC).

  8. 4. pi beta. -. gamma. coincidence system with minimally broadened pulses

    Energy Technology Data Exchange (ETDEWEB)

    Gehrke, R.J.; Johnson, L.O. (Idaho National Engineering Lab., Idaho Falls (USA))

    1982-12-15

    The performance characteristics of a new type 4..pi.. ..beta..-..gamma.. coincidence system have been measured. In contrast with the conventional 4..pi.. ..beta..-..gamma.. circuitry, which is based on a fixed pulse width (approx.= 2 ..mu..s) and a non-extendable dead time, the pulse processing circuitry in this new system is based on a minimally broadened pulse (i.e., as narrow as 0.25 ..mu..s). In this system each pulse has a different pulse width, so that the dead times for the ..beta..- and ..gamma..-ray detectors are determined by summing the measured dead time attributed by each pulse in each channel. The ..beta..-..gamma.. coincidences are defined with an overlap coincidence circuit. This system is shown to be much less sensitive to mismatch in the coincidence timing than is the conventional system. In spite of the narrower pulse widths, no spurious ..beta.. pulses are observed when the 4..pi.. proportional counter is operated near the center of its plateau. Disintegration rates were measured for calibrated sources with strength up to approx.= 10/sup 6/ Bq. These data indicate that with this new system the disintegration rates of very intense sources (approx.= 10/sup 6/ Bq) and moderately intense sources (< 10/sup 5/ Bq) can be determined with accuracies of approx.= 4% and <= 0.1%, respectively.

  9. Workshops Without Walls: broadening access to science around the world.

    Directory of Open Access Journals (Sweden)

    Betül K Arslan

    2011-08-01

    Full Text Available The National Aeronautics and Space Administration (NASA Astrobiology Institute (NAI conducted two "Workshops Without Walls" during 2010 that enabled global scientific exchange--with no travel required. The second of these was on the topic "Molecular Paleontology and Resurrection: Rewinding the Tape of Life." Scientists from diverse disciplines and locations around the world were joined through an integrated suite of collaborative technologies to exchange information on the latest developments in this area of origin of life research. Through social media outlets and popular science blogs, participation in the workshop was broadened to include educators, science writers, and members of the general public. In total, over 560 people from 31 US states and 30 other nations were registered. Among the scientific disciplines represented were geochemistry, biochemistry, molecular biology and evolution, and microbial ecology. We present this workshop as a case study in how interdisciplinary collaborative research may be fostered, with substantial public engagement, without sustaining the deleterious environmental and economic impacts of travel.

  10. Workshops Without Walls: broadening access to science around the world.

    Science.gov (United States)

    Arslan, Betül K; Boyd, Eric S; Dolci, Wendy W; Dodson, K Estelle; Boldt, Marco S; Pilcher, Carl B

    2011-08-01

    The National Aeronautics and Space Administration (NASA) Astrobiology Institute (NAI) conducted two "Workshops Without Walls" during 2010 that enabled global scientific exchange--with no travel required. The second of these was on the topic "Molecular Paleontology and Resurrection: Rewinding the Tape of Life." Scientists from diverse disciplines and locations around the world were joined through an integrated suite of collaborative technologies to exchange information on the latest developments in this area of origin of life research. Through social media outlets and popular science blogs, participation in the workshop was broadened to include educators, science writers, and members of the general public. In total, over 560 people from 31 US states and 30 other nations were registered. Among the scientific disciplines represented were geochemistry, biochemistry, molecular biology and evolution, and microbial ecology. We present this workshop as a case study in how interdisciplinary collaborative research may be fostered, with substantial public engagement, without sustaining the deleterious environmental and economic impacts of travel. PMID:21829326

  11. Peak broadening in paper chromatography and related techniques : V. Conditions for minimum separation time

    NARCIS (Netherlands)

    Lygny, C.L. de; Kok, E.C.M.

    1968-01-01

    In paper and thin-layer chromatography peak broadening is a function of the mean flow rate of the eluent, which in turn is a function of the distances of the starting point and solvent front from the eluent in the tank. Starting from the relationship between peak broadening and the positions of sta

  12. Power broadening effects on Electromagnetically Induced Transparency in $^{20}$Ne vapor

    CERN Document Server

    Lubotzky, Boaz; Kong, Tao; Katz, Nadav; Ron, Guy

    2014-01-01

    We report here the first observation of electromagnetically induced transparency (EIT) in $^{20}$Ne. The power broadening of the EIT linewidth is measured as a function of neon pressure and RF excitation power. Doppler effects on the EIT broadening are found even at low pressures and low intensities, where the linewidth should be governed only by homogeneous effects.

  13. Characteristics of S-wave Envelope Broadening in the Changbaishan Tianchi Volcano

    Institute of Scientific and Technical Information of China (English)

    Fan Xiaoping; Li Qinghe; He Haibing; Yang Congjie; Jin Shumei

    2010-01-01

    High-frequency S-wave seismogram envelopes of microearthquakes broaden with increasing travel distance,a phenomenon known as S-wave envelope broadening.Multiple forward scattering and diffraction for the random inhomogeneities along the seismic ray path are the main causes of S-wave envelope broadening,so the phenomenon of S-wave envelope broadening is used to study the inhomogeneity of the medium.The peak delay time of an S-wave,which is defined as the time lag from the direct S-wave onset to the maximum amplitude arrival of its envelope.is accepted to quantify S-wave envelope broadening.204 small earthquake records in Changbaishan Tianchi volcano were analyzed by the S-wave envelope broadening algorithm.The results show that S-wave envelope broadening in the Changbaishan Tianchi volcano is obvious,and that the peak delay time of S-wave has a positive correlation with the hypocenter distance and frequency of the Swave.The relationships between the S-wave peak delay time and the hypocenter distance for different frequency bands were obtained using the statistics method.The results are beneficial to the understanding of the S-wave envelope broadening phenomena and the quantitative research on the inhomogeneities of the crust medium in the Changbaishan Tianchi volcano region.

  14. Analysis of pulse broadening induced by the second-order PMD

    Institute of Scientific and Technical Information of China (English)

    Fu Song-Nian; Wu Chong-Qing; Shum Ping

    2005-01-01

    We propose a new conception of depolarization vector to describe the effect of depolarization induced by the second-order polarization mode dispersion (PMD). Deriving the formula of pulse broadening induced by the secondorder PMD, we find that the polarization-dependent chromatic dispersion (PCD) always enhances the pulse broadening.However the depolarization vector decreases the pulse broadening. The pulse broadening is correlated with the bit-rate of a transmission system. By adjusting the directions of the Stokes vector of initial state of polarization, initial firstorder polarization dispersion vector and depolarization vector to be parallel to each other, one can obtain an optimum dispersion compensation.But when the PCD is not equal to zero, the optimum dispersion cannot achieve a complete compensation, and the minimum pulse broadening is equal to σ = ( 2/4) (DCF/T0).

  15. Stark Broadening Analysis Using Optical Spectroscopy of the Dense Plasma Focus

    Science.gov (United States)

    Ross, Patrick; Bennett, Nikki; Dutra, Eric; Hagen, E. Chris; Hsu, Scott; Hunt, Gene; Koch, Jeff; Waltman, Tom; NSTec DPF Team

    2015-11-01

    To aid in validating numerical modeling of MA-class dense plasma focus (DPF) devices, spectroscopic measurements of the Gemini Dense Plasma Focus (DPF) were performed using deuterium and deuterium/dopant (argon/krypton) gas. The spectroscopic measurements were made using a fiber-coupled spectrometer and streak camera. Stark line-broadening analysis was applied to the deuterium beta emission (486 nm) in the region near the breakdown of the plasma and during the run-down and run-in phases of the plasma evolution. Densities in the range of 1e17 to low 1e18 cm-3 were obtained. These values are in agreement with models of the DPF performed using the LSP code. The spectra also show a rise and fall with time, indicative of the plasma sheath passing by the view port. Impurity features were also identified in the spectra which grew in intensity as the gas inside the DPF was discharged repeatedly without cycling. Implications of this impurity increase for D-T discharges (without fresh gas fills between every discharge) will be discussed. This work was done by National Security Technologies, LLC, under Contract No. DE-AC52-06NA25946, and by Los Alamos National Laboratory, under Contract no. DE-AC52-06NA25396 with the U.S. Department of Energy. DOE/NV/25946-2515.

  16. Voigt Size-Strain Broadening Of Pd Thin Films

    Directory of Open Access Journals (Sweden)

    Vladimir Zucha

    2004-01-01

    Full Text Available Pd thin films were deposited onto Si (100 and glass/Pd/etching substrates by means of r.f. reactive sputtering under the same sputtering condition in order to appreciate the influence of substrate structure. The aim of this study was to appreciate the main X-ray diffraction line profile characteristic by the approximation method. As an approximation function was used the Voigt profile which was calculated by convolution of Gaussian and Cauchy profiles. As an instrumental standart was used ceramic Al2O3 from Nist. Results of size-strain analysis was obtained according to Langford method for one diffraction line and method suggested by Balzar and Ledbetter for two orders of the same diffraction line.

  17. Homogeneous Broadening of Optical Transitions in Organic Mixed Crystals

    NARCIS (Netherlands)

    Vries, Harmen de; Wiersma, Douwe A.

    1976-01-01

    We have used the phenomenon of laser-induced molecular photodissociation to determine the homogeneous linewidth at 2 K of the origin (zero-phonon line) and a vibronic transition in the mixed-crystal absorption spectrum of dimethyl s-tetrazine in durene. From the measured 55-MHz (upper limit) homogen

  18. Time sequence spectroscopy of AW UMa. The 518 nm Mg I triplet region analyzed with Broadening Functions

    CERN Document Server

    Rucinski, Slavek M

    2014-01-01

    High resolution spectroscopic observations of AW UMa, obtained on three consecutive nights with the median time resolution of 2.1 minutes, have been analyzed using the Broadening Functions method in the spectral window of 22.75 nm around the 518 nm Mg I triplet region. Doppler images of the system reveal the presence of vigorous mass motions within the binary system. The ample evidence of a non-solid-body velocity field puts into question the contact-binary model based on solid-body equipotentials. AW UMa is a semi-detached binary; the mass transfer takes place from the more massive to the less massive component. The primary, a fast-rotating star with Vsin i = 181.4 km/s, is covered by inhomogeneities: very slowly drifting spots and a dense network of ripples more closely participating in its rotation. The spectral lines of the primary show an additional broadening component (called the "pedestal") which originates either in the equatorial regions which rotate faster than the rest of the star by about 50 km/s...

  19. Application of Energy Window Concept in Doppler Broadening of {sup 238}U Cross Section

    Energy Technology Data Exchange (ETDEWEB)

    Khassnov, Azamat; Choi, Soo Young; Lee, Deok Jung [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

    2014-10-15

    Currently, the NJOY code is used for construction and Doppler broadening of microscopic cross sections. There exist several methods or formalisms to produce microscopic cross sections and there are also different methods of Doppler broadening. In this paper, Multi-Level Breit-Wigner (MLBW) formalism and the Psi method are used for generation and Doppler broadening of the resonance cross section. Accuracy of the energy window concept applied MLBW (EW MLBW) Doppler broadened cross section was compared with that of the cross section generated by conventional MLBW (Con MLBW) formalism for {sup 2}38U isotope using MATLAB. The conventional method requires Doppler broadening of all resonances, including resonances far from the target energy point, which do not change much with respect to the temperature change. The energy window concept makes Doppler broadening possible with a smaller number of resonances neighboring to the energy point we are interested in, and just adds up 0 K temperature cross sections of other resonances. Multi-level Breit-Wigner formalism and the Doppler broadening method were used to construct microscopic cross sections of {sup 238}U at different temperatures. The energy window concept was applied only for the 1st resonance energy region (4.5∼11.2 eV). The energy window concept demonstrates high competitiveness because the relative differences were less than 0.0016% for all types of cross sections. The advantage of the energy window concept is that the number of resonances broadened for every energy point is significantly reduced, which allows a reduction of computation time by almost 45 % of Doppler broadening time of the cross section generation at temperatures higher than 0 K.

  20. Application of Energy Window Concept in Doppler Broadening of 238U Cross Section

    International Nuclear Information System (INIS)

    Currently, the NJOY code is used for construction and Doppler broadening of microscopic cross sections. There exist several methods or formalisms to produce microscopic cross sections and there are also different methods of Doppler broadening. In this paper, Multi-Level Breit-Wigner (MLBW) formalism and the Psi method are used for generation and Doppler broadening of the resonance cross section. Accuracy of the energy window concept applied MLBW (EW MLBW) Doppler broadened cross section was compared with that of the cross section generated by conventional MLBW (Con MLBW) formalism for 238U isotope using MATLAB. The conventional method requires Doppler broadening of all resonances, including resonances far from the target energy point, which do not change much with respect to the temperature change. The energy window concept makes Doppler broadening possible with a smaller number of resonances neighboring to the energy point we are interested in, and just adds up 0 K temperature cross sections of other resonances. Multi-level Breit-Wigner formalism and the Doppler broadening method were used to construct microscopic cross sections of 238U at different temperatures. The energy window concept was applied only for the 1st resonance energy region (4.5∼11.2 eV). The energy window concept demonstrates high competitiveness because the relative differences were less than 0.0016% for all types of cross sections. The advantage of the energy window concept is that the number of resonances broadened for every energy point is significantly reduced, which allows a reduction of computation time by almost 45 % of Doppler broadening time of the cross section generation at temperatures higher than 0 K

  1. Influence of Doppler-broadening on absorption-dispersion properties in a resonant coherent medium

    Institute of Scientific and Technical Information of China (English)

    Xu Wei-Hua; Gao Jin-Yue

    2005-01-01

    We investigate the influence of Doppler broadening on absorption-dispersion properties in a four-level atomic system that can evolve from a normal dispersion to an anomalous dispersion. Our results show that the absorption-dispersion properties become strongly dependent on the propagation directions of the applied fields if Doppler broadening is taken into account. Especially, the switchover in the sign of the dispersion is still achievable even in the presence of Doppler broadening if properly arranging the propagation directions of the applied fields, which is in contrast with the otherwise behaviours in some other configurations.

  2. Measurements of foreign gas pressure shift and broadening effects in the (1-0) band of CO with N[sub 2] and Ar

    Energy Technology Data Exchange (ETDEWEB)

    Anselm, N.; Yamada, K.M.T.; Schieder, R.; Winnewisser, G. (Univ. zu Koeln, Koeln (Germany))

    1993-09-01

    The pressure broadenings and shifts of rovibrational transitions of the CO fundamental band with foreign gases, argon and nitrogen, were measured by a tunable diode laser spectrometer. High J ([le]34) R-branch and low J R- and P-branch transitions have been recorded with very high accuracy (5 [times] 10[sup [minus]5] cm[sup [minus]1]). These highly accurate and very sensitive measurements became possible with a newly designed shock-isolated laser cold head and the application of an extremely stable 50-m multiple-path cell of the Herriott type. The accuracy of the line shift and broadening coefficients obtained in the present study is about 3 [times] 10[sup [minus]4] cm[sup [minus]1]/bar.

  3. Anomalous spectral lines and relic quantum nonequilibrium

    CERN Document Server

    Underwood, Nicolas G

    2016-01-01

    We describe general features that might be observed in the line spectra of relic cosmological particles should quantum nonequilibrium be preserved in their statistics. According to our arguments, these features would represent a significant departure from those of a conventional origin. Among other features, we find a possible spectral broadening (for incident photons) that is proportional to the energy resolution of the recording telescope (and so could be orders of magnitude larger than any intrinsic broadening). Notably, for a range of possible initial conditions we find the possibility of spectral line `narrowing' whereby a telescope could observe a spectral line which is narrower than it should conventionally be able to resolve. We briefly discuss implications for the indirect search for dark matter.

  4. Interference effects and Stark broadening in XUV intrashell transitions in aluminum under conditions of intense XUV free-electron-laser irradiation

    Science.gov (United States)

    Galtier, E.; Rosmej, F. B.; Calisti, A.; Talin, B.; Mossé, C.; Ferri, S.; Lisitsa, V. S.

    2013-03-01

    Quantum mechanical interference effects in the line broadening of intrashell transitions are investigated for dense plasma conditions. Simulations that involved LSJ-split level structure and intermediate coupling discovered unexpected strong line narrowing for intrashell transitions L-L while M-L transitions remained practically unaffected by interference effects. This behavior allows a robust study of line narrowing in dense plasmas. Simulations are carried out for XUV transitions of aluminum that have recently been observed in experiments with the FLASH free-electron laser in Hamburg irradiating solid aluminum samples with intensities greater than 1016 W/cm2. We explore the advantageous case of Al that allows, first, simultaneous observation of M-L transitions and L-L intrashell transitions with high-resolution grating spectrometers and, second, has a convenient threshold to study interference effects at densities much below solid. Finally, we present simulations at near solid density where the line emission transforms into a quasicontinuum.

  5. Evolution of low-frequency features in the CMB spectrum due to stimulated Compton scattering and Doppler-broadening

    CERN Document Server

    Chluba, J

    2008-01-01

    We discuss a new solution of the Kompaneets-equation for physical situations in which low frequency photons, forming relatively narrow spectral details, are Compton scattered in an isotropic, infinite medium with an intense ambient blackbody field that is very close to full thermodynamic equilibrium with the free electrons. In this situation the background-induced stimulated Compton scattering slows down the motion of photons toward higher frequencies by a factor of 3 in comparison with the solution that only takes into account Doppler-broadening and boosting. This new solution is important for detailed computations of cosmic microwave background spectral distortions arising due to uncompensated atomic transitions of hydrogen and helium in the early Universe. In addition we derive another analytic solution that only includes the background-induced stimulated Compton scattering and is valid for power-law ambient radiation fields. This solution might have interesting applications for radio lines arising inside ...

  6. High-resolution spectroscopy for Doppler-broadening ion temperature measurements of implosions at the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Koch, J. A.; Stewart, R. E.; Beiersdorfer, P.; Shepherd, R.; Schneider, M. B.; Miles, A. R.; Scott, H. A.; Smalyuk, V. A.; Hsing, W. W. [Lawrence Livermore National Laboratory, P.O. Box 808, L-493, Livermore, California 94550 (United States)

    2012-10-15

    Future implosion experiments at the national ignition facility (NIF) will endeavor to simultaneously measure electron and ion temperatures with temporal and spatial resolution in order to explore non-equilibrium temperature distributions and their relaxation toward equilibrium. In anticipation of these experiments, and with understanding of the constraints of the NIF facility environment, we have explored the use of Doppler broadening of mid-Z dopant emission lines, such as krypton He-{alpha} at 13 keV, as a diagnostic of time- and potentially space-resolved ion temperature. We have investigated a number of options analytically and with numerical raytracing, and we have identified several promising candidate spectrometer designs that meet the expected requirements of spectral and temporal resolution and data signal-to-noise ratio for gas-filled exploding pusher implosions, while providing maximum flexibility for use on a variety of experiments that potentially include burning plasma.

  7. A unified numerical model of collisional depolarization and broadening rates due to hydrogen atom collisions

    CERN Document Server

    Derouich, M; Barklem, P S

    2015-01-01

    Interpretation of solar polarization spectra accounting for partial or complete frequency redistribution requires data on various collisional processes. Data for depolarization and polarization transfer are needed but often missing, while data for collisional broadening are usually more readily available. Recent work by Sahal-Br\\'echot and Bommier concluded that despite underlying similarities in the physics of collisional broadening and depolarization processes, relationships between them are not possible to derive purely analytically. We aim to derive accurate numerical relationships between the collisional broadening rates and the collisional depolarization and polarization transfer rates due to hydrogen atom collisions. Such relationships would enable accurate and efficient estimation of collisional data for solar applications. Using earlier results for broadening and depolarization processes based on general (i.e. not specific to a given atom), semi-classical calculations employing interaction potentials...

  8. Smile to see the forest: Facially expressed positive emotions broaden cognition.

    Science.gov (United States)

    Johnson, Kareem J; Waugh, Christian E; Fredrickson, Barbara L

    2010-02-19

    The broaden hypothesis, part of Fredrickson's (1998, 2001) broaden-and-build theory, proposes that positive emotions lead to broadened cognitive states. Here, we present evidence that cognitive broadening can be produced by frequent facial expressions of positive emotion. Additionally, we present a novel method of using facial electromyography (EMG) to discriminate between Duchenne (genuine) and non-Duchenne (non-genuine) smiles. Across experiments, Duchenne smiles occurred more frequently during positive emotion inductions than neutral or negative inductions. Across experiments, Duchenne smiles correlated with self-reports of specific positive emotions. In Experiment 1, high frequencies of Duchenne smiles predicted increased attentional breadth on a global-local visual processing task. In Experiment 2, high frequencies of Duchenne smiles predicted increased attentional flexibility on a covert attentional orienting task. These data underscore the value of using multiple methods to measure emotional experience in studies of emotion and cognition. PMID:23275681

  9. A universal equation for computing the beam broadening of incident electrons in thin films.

    Science.gov (United States)

    Gauvin, Raynald; Rudinsky, Samantha

    2016-08-01

    A universal equation for computing the beam broadening of incident electrons in thin films is presented. This equation is based on the concepts of anomalous diffusion with the Hurst exponent H. When the thickness to elastic mean free path ratio, t/λ, is greater than 1, the Hurst exponent goes to 0.5 and this random walk behavior leads to the Goldstein et al. [1] beam broadening equation when non-relativistic screened Rutherford elastic cross-sections are used. When t/λ≪1, the lack of elastic collisions for the electron trajectories gives an H exponent of 1 and a different beam broadening equation is obtained. A general equation to compute the beam broadening that takes into account the variation of H with t/λ is presented and this equation was fitted and validated with Monte Carlo simulations of electron trajectories in thin films. PMID:27161415

  10. Effects of positive mood on attention broadening for self-related information

    OpenAIRE

    Grol, Maud; Koster, Ernst; Bruyneel, Lynn; Raedt, Rudi

    2014-01-01

    Studies on cognitive effects of positive emotions have associated positive emotions to broadened attention. Given the widely investigated relationship between self-focused attention and mood, it is important to investigate the effect of positive mood on visuospatial attention for self-related information. We used a performance-based measure to assess fluctuations in attentional broadening from self-related contrasted to not-self-related information. In Experiment 1, we checked that the self-r...

  11. Analysis of compressive failure of layered materials by kink band broadening

    DEFF Research Database (Denmark)

    Jensen, Henrik Myhre

    1999-01-01

    Failure by steady state kink band broadening in uni-directional fibre composites or layered materials is analysed. An incremental scheme for calculation of kink band broadening stresses and lock-up conditions in the band for arbitrary material behaviour is presented. The method is illustrated...... by material data which are representative for polymer matrix composites for which experimental work exists. (C) 1999 Elsevier Science Ltd. All rights reserved....

  12. Reducing the impact of inhomogeneous broadening on quantum dot based electromagnetically induced transparency

    DEFF Research Database (Denmark)

    Hansen, Per Lunnemann; Mørk, Jesper

    2009-01-01

    Slow light based on electromagnetically induced transparency in an inhomogeneously broadened quantum dot medium is investigated theoretically. Three schemes, , V, and Λ, are compared and it is shown that the V-scheme gives a group velocity that is more than three orders of magnitude smaller compa...... compared to the - and Λ-schemes. The physical mechanisms that make the V-scheme less vulnerable to inhomogeneous broadening are analyzed and discussed...

  13. Positive emotions broaden the scope of attention and thought-action repertoires

    OpenAIRE

    Fredrickson, Barbara L.; Branigan, Christine

    2005-01-01

    The broaden-and-build theory (Fredrickson, 1998, 2001) hypothesises that positive emotions broaden the scope of attention and thought-action repertoires. Two experiments with 104 college students tested these hypotheses. In each, participants viewed a film that elicited (a) amusement, (b) contentment, (c) neutrality, (d) anger, or (e) anxiety. Scope of attention was assessed using a global-local visual processing task (Experiment 1) and thought-action repertoires were assessed using a Twenty ...

  14. Speed-dependent spectral line profile including line narrowing and mixing

    Science.gov (United States)

    Kochanov, Victor P.

    2016-07-01

    A line profile model was developed that accounts for all essential underlying physical mechanisms. The model is based on the quantum-mechanical collision integral kernel calculated for intermolecular interaction potentials ∝r-n with n=3…6 where r is the distance between colliding molecules. It was shown that collisions of molecules with scattering on classical small angles flatten the line profile. The relative flattening reaches 10% for n=3 and has a smaller value, ~2%, for n=6 in conditions of inhomogeneous line broadening. An algebraic expression for the line profile was obtained, which allows processing recorded spectra with preliminary estimation and constraint of some of the profile's parameters.

  15. Line-of-sight statistical methods for turbulent medium: VCS for emission and absorption lines

    CERN Document Server

    Pogosyan, D

    2009-01-01

    We present an overview of the Velocity Coordinate Spectrum (VCS), a new technique for studying astrophysical turbulence that utilizes the line-of-sight statistics of Doppler-broadened spectral lines. We consider the retrieval of turbulence spectra from emission intensity observations of both high and low spatial resolution and find that the VCS allows one to study turbulence even when the emitting turbulent volume is not spatially resolved. This opens interesting prospects for using the technique for extragalactic research. VCS developed for spectral emission lines is applicable to absorption lines as well if the optical depth is used instead of intensity. VCS for absorption lines in point-source spectra benefit from effectively narrow beam and does not require dense sky coverage by sampling directions. Even strongly saturated absorption lines still carry the information about the small scale turbulence, albeit limited to the wings of a line. Combining different absorption lines one can develop tomography of ...

  16. Multispectrum analysis of the ν9 band of 12C2H6: Positions, intensities, self- and N2-broadened half-width coefficients

    International Nuclear Information System (INIS)

    Line positions, intensities, Lorentz self- and N2-broadened half-width coefficients have been measured for PQ3, PQ2, PQ1, RQ0, RQ1, RQ2, and RQ3 sub-band transitions in the ν9 fundamental band of 12C2H6. A multispectrum nonlinear least-squares fitting technique was used to fit up to 17 high-resolution (∼0.00156 cm-1), room temperature absorption spectra of pure (99.99% chemical purity) natural sample of ethane and lean mixtures of the high-purity ethane diluted with N2. A Bruker IFS 120HR Fourier transform spectrometer located at the Pacific Northwest National Laboratory (PNNL), in Richland, Washington was used to record the data. A standard Voigt line shape was assumed to fit all the data since no line mixing or other non Voigt line shapes were required to fit any of the spectra used in the analysis. Short spectral intervals (∼2-2.5 cm-1) of all 17 spectra covering a specific PQ or RQ sub-band were fit simultaneously. For the first time in an ethane band, pressure-broadened half-width coefficients were determined for the torsional-split components. However, for better reliability of the retrieved coefficients for the weaker components (transitions with large intensity ratios of 4:1 or 3:1 for most K levels between the strong and weak components), constraints were used such that the half-width coefficients of both torsional-split components for a given J were identical for a specific broadening gas. No pressure-induced shift coefficients were necessary to fit the spectra to their noise level. The present study revealed for the first time the dependence of self- and N2-broadened half-width coefficients upon the J, K quantum numbers of the transitions in ethane. A number of transitions belonging to the ν9+ν4-ν4 and the ν9+2ν4-2ν4 hot bands were also observed in the fitted regions and measurements were made when possible.

  17. Effect of Surface Adsorption on Temporal and Spatial Broadening in Micro Free Flow Electrophoresis.

    Science.gov (United States)

    Geiger, Matthew; Harstad, Rachel K; Bowser, Michael T

    2015-12-01

    Analyte adsorption onto surfaces presents a challenge for many separations, often becoming a significant source of peak broadening and asymmetry. We have shown that surface adsorption has no effect on peak position or spatial broadening in micro free flow electrophoresis (μFFE) separations. Surface adsorption does affect the time it takes an analyte to travel through the μFFE separation channel and therefore contributes to temporal broadening. These results were confirmed using μFFE separations of fluorescein, rhodamine 110, and rhodamine 123 in a low ionic strength buffer to promote surface adsorption. Peak widths and asymmetries were measured in both the temporal and spatial dimensions. Under these conditions rhodamine 123 exhibited significant interactions with the separation channel surface, causing increased peak broadening and asymmetry in the temporal dimension. Broadening or asymmetry in the spatial dimension was not significantly different than that of fluorescein, which did not interact with the capillary surface. The effect of strong surface interactions was assessed using μFFE separations of Chromeo P503 labeled myoglobin and cytochrome c. Myoglobin and cytochrome c were well resolved and gave rise to symmetrical peaks in the spatial dimension even under conditions where permanent adsorption onto the separation channel surface occurred. PMID:26496470

  18. Photon storage in Lambda-type optically dense atomic media. III. Effects of inhomogeneous broadening

    CERN Document Server

    Gorshkov, A V; Lukin, M D; Sørensen, A S; Andre, Axel; Gorshkov, Alexey V.; Lukin, Mikhail D.; Sorensen, Anders S.

    2006-01-01

    In a recent paper [A.V. Gorshkov et al., e-print quant-ph/0604037 (2006)] and in the two preceding papers [A.V. Gorshkov et al., e-print quant-ph/0612082 (2006); e-print quant-ph/0612083 (2006)], we used a universal physical picture to optimize and demonstrate equivalence between a wide range of techniques for storage and retrieval of photon wave packets in homogeneously broadened Lambda-type atomic media, including the adiabatic reduction of the photon group velocity, pulse-propagation control via off-resonant Raman techniques, and photon-echo based techniques. In the present paper, we generalize this treatment to include inhomogeneous broadening both in atomic vapors and in solid state systems. In particular, we show that for the case of Doppler-broadened atoms, at high enough optical depth, all atoms contribute coherently to the storage process as if the medium were homogeneously broadened. Furthermore, we discuss the advantages and limitations of reversing the inhomogeneous broadening during the storage t...

  19. Physical limits to broadening compensation in a linear slow light system.

    Science.gov (United States)

    Gonzalez-Herraez, Miguel; Thévenaz, Luc

    2009-03-16

    The dispersion experienced by a signal in a slow light system leads to a significant pulse broadening and sets a limit to the maximum delay actually achievable by the system. To overcome this limitation, a substantial research effort is currently being carried out, and successful strategies to reduce distortion in linear slow light systems have already been demonstrated. Recent theoretical and experimental works have even claimed the achievement of zero-broadening of pulses in these systems. In this work we obtain some physical limits to broadening compensation in linear slow light systems based on simple Fourier analysis. We show that gain and dispersion broadening can never compensate in such a system. Additionally, it is simply proven that all the linear slow light systems that introduce a low-pass filtering of the signal (a reduction in the signal root-mean- square spectral width), will always cause pulse broadening. These demonstrations are done using a rigorous shape-independent definition of pulse width (the root-mean-square temporal width) and arguments borrowed from time-frequency analysis. PMID:19293903

  20. Implementation of On-the-Fly Doppler Broadening in MCNP5 for Multiphysics Simulation of Nuclear Reactors

    Energy Technology Data Exchange (ETDEWEB)

    William Martin

    2012-11-16

    A new method to obtain Doppler broadened cross sections has been implemented into MCNP, removing the need to generate cross sections for isotopes at problem temperatures. Previous work had established the scientific feasibility of obtaining Doppler-broadened cross sections "on-the-fly" (OTF) during the random walk of the neutron. Thus, when a neutron of energy E enters a material region that is at some temperature T, the cross sections for that material at the exact temperature T are immediately obtained by interpolation using a high order functional expansion for the temperature dependence of the Doppler-broadened cross section for that isotope at the neutron energy E. A standalone Fortran code has been developed that generates the OTF library for any isotope that can be processed by NJOY. The OTF cross sections agree with the NJOY-based cross sections for all neutron energies and all temperatures in the range specified by the user, e.g., 250K - 3200K. The OTF methodology has been successfully implemented into the MCNP Monte Carlo code and has been tested on several test problems by comparing MCNP with conventional ACE cross sections versus MCNP with OTF cross sections. The test problems include the Doppler defect reactivity benchmark suite and two full-core VHTR configurations, including one with multiphysics coupling using RELAP5-3D/ATHENA for the thermal-hydraulic analysis. The comparison has been excellent, verifying that the OTF libraries can be used in place of the conventional ACE libraries generated at problem temperatures. In addition, it has been found that using OTF cross sections greatly reduces the complexity of the input for MCNP, especially for full-core temperature feedback calculations with many temperature regions. This results in an order of magnitude decrease in the number of input lines for full-core configurations, thus simplifying input preparation and reducing the potential for input errors. Finally, for full-core problems with multiphysics

  1. Curriculum of broaden education and theory of teaching activity in school Physical Education

    Directory of Open Access Journals (Sweden)

    Sirléia Silvano

    2016-05-01

    Full Text Available This paper focuses on the conception of curriculum with broaden character in Physical Education and Davidov and Leontiev’s learning theory as possibility of focusing on human education in the omnilateral perspective. We endorse the necessity that the curriculum dynamics – dealing with knowledge, school systematization and standardization of school practices – becomes effective in a curriculum of broaden character. We consider that dealing with knowledge involves the necessity to create conditions that promote the transmission and assimilation of school knowledge. We refer therefore to a scientific direction of the teaching process, in other words, that the teacher leads the student to enter into study activity; from abstract knowledge rising to concrete theoretical knowledge, which is brought about by curriculum organization from a broaden conception.

  2. Self-referencing of an on-chip soliton Kerr frequency comb without external broadening

    CERN Document Server

    Brasch, Victor; Jost, John D; Geiselmann, Michael; Kippenberg, Tobias J

    2016-01-01

    Self-referencing turns pulsed laser systems into self-referenced frequency combs. Such frequency combs allow counting of optical frequencies and have a wide range of applications. The required optical bandwidth to implement self-referencing is typically obtained via nonlinear broadening in optical fibers. Recent advances in the field of Kerr frequency combs have provided a path towards the development of compact frequency comb sources that provide broadband frequency combs, exhibit microwave repetition rates and that are compatible with on-chip photonic integration. These devices have the potential to significantly expand the use of frequency combs. Yet to date self-referencing of such Kerr frequency combs has only been attained by applying conventional, fiber based broadening techniques. Here we demonstrate external broadening-free self-referencing of a Kerr frequency comb. An optical spectrum that spans two-thirds of an octave is directly synthesized from a continuous wave laser-driven silicon nitride micro...

  3. Dielectric spectra broadening as the signature of dipole-matrix interaction. I. Water in nonionic solutions.

    Science.gov (United States)

    Levy, Evgeniya; Puzenko, Alexander; Kaatze, Udo; Ishai, Paul Ben; Feldman, Yuri

    2012-03-21

    Whenever water interacts with another dipolar entity, a broadening of its dielectric relaxation occurs. Often this broadening can be described by the Cole-Cole (CC) spectral function. A new phenomenological approach has been recently presented [A. Puzenko, P. Ben Ishai, and Y. Feldman, Phys. Rev. Lett. 105, 037601 (2010)] that illustrates a physical mechanism of the dipole-matrix interaction underlying the CC behavior in complex systems. By considering the relaxation amplitude Δε, the relaxation time τ, and the broadening parameter α, one can construct a set of 3D trajectories, representing the dynamic behavior of different systems under diverse conditions. Our hypothesis is that these trajectories will contribute to a deeper understanding of the dielectric properties of complex systems. The paper demonstrates how the model describes the state of water in aqueous solutions of non-ionic solutes. For this purpose complex dielectric spectra for aqueous solutions of D-glucose and D-fructose are analyzed.

  4. Ghost features in Doppler-broadened spectra of rovibrational transitions in trapped HD$^+$ ions

    CERN Document Server

    Patra, Sayan

    2016-01-01

    Doppler broadening plays an important role in laser rovibrational spectroscopy of trapped deuterated molecular hydrogen ions (HD$^+$), even at the millikelvin temperatures achieved through sympathetic cooling by laser-cooled beryllium ions. Recently, Biesheuvel \\textit{et al.} \\cite{Biesheuvel2016} presented a theoretical lineshape model for such transitions which not only considers linestrengths and Doppler broadening, but also the finite sample size and population redistribution by blackbody radiation, which are important in view of the long storage and probe times achievable in ion traps. Here, we employ the rate equation model developed by Biesheuvel \\textit{et al.} to theoretically study the Doppler-broadened hyperfine structure of the $(v,L):(0,3)\\rightarrow(4,2)$ rovibrational transition in HD$^+$ at 1442~nm. We observe prominent yet hitherto unrecognized ghost features in the simulated spectrum, whose positions depend on the Doppler width, transition rates, and saturation levels of the hyperfine compo...

  5. Single photon quantum non-demolition measurements in the presence of inhomogeneous broadening

    International Nuclear Information System (INIS)

    Electromagnetically induced transparency (EIT) has often been proposed for generating nonlinear optical effects at the single photon level; in particular, as a means to effect a quantum non-demolition measurement of a single-photon field. Previous treatments have usually considered homogeneously broadened samples, but realizations in any medium will have to contend with inhomogeneous broadening. Here we reappraise an earlier scheme (Munro et al 2005 Phys. Rev. A 71 033819) with respect to inhomogeneities and show an alternative mode of operation that is preferred in an inhomogeneous environment. We further show the implications of these results on a potential implementation in diamond-containing nitrogen-vacancy colour centres.

  6. Saturation broadening effect in an InP photonic-crystal nanocavity switch

    DEFF Research Database (Denmark)

    Yu, Yi; Palushani, Evarist; Heuck, Mikkel;

    2014-01-01

    Pump-probe measurements on InP photonic-crystal nanocavities show large-contrast fast switching at low pulse energy. For large pulse energies, large resonance shifts passing across the probe lead to switching contrast saturation and switching time-window broadening. © 2014 OSA.......Pump-probe measurements on InP photonic-crystal nanocavities show large-contrast fast switching at low pulse energy. For large pulse energies, large resonance shifts passing across the probe lead to switching contrast saturation and switching time-window broadening. © 2014 OSA....

  7. The density broadening in a sodium F=2 condensate detected by a pulse train

    Directory of Open Access Journals (Sweden)

    Jianing Han

    2011-09-01

    Full Text Available The dipole-blockaded sodium clock transition has been detected by high resolution microwave spectroscopy, the multiple-pulse spectroscopy. This spectroscopic technique has been first used to detect the density broadening and shifting in a Sodium Bose Einstein Condensate (BEC by probing the sodium clock-transition. Moreover, by narrowing the pulse-width of the pulses, some of the broadening mechanisms can be partially reduced. The results reported here are essential steps toward the ground-state quantum computing, few-body spectroscopy, spin squeezing and quantum metrology.

  8. Effect of PMD-induced Pulse Broadening on Sensitivity and Frequency Spectrum

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The PMD-induced pulse broadening may cause the degradation of receiver sensitivity and has negative effects on the power spectrum of received signals. The expressions of PMD-induced pulse broadening effects on receiver sensitivity are derived based on the concept of mean square pulse width. The effects of PMD on the spectrum of received power are analyzed in detail. Finally, the scheme is discussed with which the power of a certain frequency component is extracted as a feedback control signal in a PMD compensation system.

  9. Uncovering Tacit Knowledge: A Pilot Study to Broaden the Concept of Knowledge in Knowledge Translation

    Directory of Open Access Journals (Sweden)

    Edwards Nancy

    2011-08-01

    Full Text Available Abstract Background All sectors in health care are being asked to focus on the knowledge-to-practice gap, or knowledge translation, to increase service effectiveness. A social interaction approach to knowledge translation assumes that research evidence becomes integrated with previously held knowledge, and practitioners build on and co-create knowledge through mutual interactions. Knowledge translation strategies for public health have not provided anticipated positive changes in evidence-based practice, possibly due in part to a narrow conceptualization of knowledge. More work is needed to understand the role of tacit knowledge in decision-making and practice. This pilot study examined how health practitioners applied tacit knowledge in public health program planning and implementation. Methods This study used a narrative approach, where teams from two public health units in Ontario, Canada were conveniently selected. Respondents participated in individual interviews and focus groups at each site. Questions were designed to understand the role of tacit knowledge as it related to the program planning process. Data were analyzed through a combination of content analysis and thematic comparison. Results The findings highlighted two major aspects of knowledge that arose: the use of tacit knowledge and the integration of tacit and explicit knowledge. Tacit knowledge included: past experiences, organization-specific knowledge, community contextual knowledge, and the recognition of the tacit knowledge of others. Explicit knowledge included: research literature, the Internet, popular magazines, formal assessments (surveys and interviews, legislation and regulations. Participants sometimes deliberately combined tacit and explicit knowledge sources in planning. Conclusions This pilot demonstrated that front-line public health workers draw upon both tacit knowledge and explicit knowledge in their everyday lived reality. Further, tacit knowledge plays an

  10. The Second Workshop on Lineshape Code Comparison: Isolated Lines

    Directory of Open Access Journals (Sweden)

    Spiros Alexiou

    2014-05-01

    Full Text Available In this work, we briefly summarize the theoretical aspects of isolated line broadening. We present and discuss test run comparisons from different participating lineshape codes for the 2s-2p transition for LiI, B III and NV.

  11. Submillimeter-wave measurements of N2 and O2 pressure broadening for HO2 radical generated by Hg-photosensitized reaction

    International Nuclear Information System (INIS)

    The N2 and O2 pressure broadening coefficients of the pure rotational transitions at 625.66 GHz (NKaKc=101-9-100-10, J=10.5-10.5) and 649.70 GHz (NKaKc=102-9-92-8, J=9.5-8.5) in the vibronic ground state X2A′ of the perhydroxyl (HO2) radical have been determined by precise laboratory measurements. For the production of HO2, the mercury-photosensitized reaction of the H2 and O2 precursors was used to provide an optimum condition for measurement of the pressure broadening coefficient. The Superconducting Submillimeter-wave Limb Emission Sounder (SMILES) was designed to monitor the volume mixing ratio of trace gases including HO2 in the Earth's upper atmosphere using these transitions. The precise measurement of pressure broadening coefficient γ in terms of the half width at half maximum is required in order to retrieve the atmospheric volume mixing ratio. In this work, γ coefficients of the 625.66 GHz transition were determined for N2 and O2 at room temperature as γ(N2)=4.085±0.049 MHz/Torr and γ(O2)=2.578±0.047 MHz/Torr with 3σ uncertainty. Similarly, the coefficients of the 649.70 GHz transition were determined as γ(N2)=3.489±0.094 MHz/Torr and γ(O2)=2.615±0.099 MHz/Torr. The air broadening coefficients for the 625.66 GHz and 649.70 GHz lines were estimated at γ(air)=3.769±0.067 MHz and 3.298±0.099 MHz respectively, where the uncertainty includes possible systematic errors. The newly determined coefficients are compared with previous results and we discuss the advantage of the mercury-photosensitized reaction for HO2 generation. In comparison with those of other singlet molecules, the pressure broadening coefficients of the HO2 radical are not much affected by the existence of an unpaired electron.

  12. Broad iron lines in Active Galactic Nuclei

    CERN Document Server

    Fabian, A C; Reynolds, C S; Young, A J

    2000-01-01

    An intrinsically narrow line emitted by an accretion disk around a black hole appears broadened and skewed as a result of the Doppler effect and gravitational redshift. The fluorescent iron line in the X-ray band at 6.4-6.9keV is the strongest such line and is seen in the X-ray spectrum of many active galactic nuclei and, in particular, Seyfert galaxies. It is an important diagnostic with which to study the geometry and other properties of the accretion flow very close to the central black hole. The broad iron line indicates the presence of a standard thin accretion disk in those objects, often seen at low inclination. The broad iron line has opened up strong gravitational effects around black holes to observational study with wide-reaching consequences for both astrophysics and physics.

  13. Line radiative transfer and statistical equilibrium*

    Directory of Open Access Journals (Sweden)

    Kamp Inga

    2015-01-01

    Full Text Available Atomic and molecular line emission from protoplanetary disks contains key information of their detailed physical and chemical structures. To unravel those structures, we need to understand line radiative transfer in dusty media and the statistical equilibrium, especially of molecules. I describe here the basic principles of statistical equilibrium and illustrate them through the two-level atom. In a second part, the fundamentals of line radiative transfer are introduced along with the various broadening mechanisms. I explain general solution methods with their drawbacks and also specific difficulties encountered in solving the line radiative transfer equation in disks (e.g. velocity gradients. I am closing with a few special cases of line emission from disks: Radiative pumping, masers and resonance scattering.

  14. Doppler radar spectral width broadening due to beamwidth and wind shear

    Directory of Open Access Journals (Sweden)

    G. D. Nastrom

    Full Text Available The spectral width observed by Doppler radars can be due to several effects including the atmospheric turbulence within the radar sample volume plus effects associated with the background flow and the radar geometry and configuration. This study re-examines simple models for the effects due to finite beamwidth and vertical shear of the horizontal wind. Analytic solutions of 1- and 2-dimensional models are presented. Comparisons of the simple 2-dimensional model with numerical integrations of a 3-dimensional model with a symmetrical Gaussian beam show that the 2-dimensional model is usually adequate. The solution of the 2-dimensional model gives a formula that can be applied easily to large data sets. Analysis of the analytic solutions of the 2-dimensional model for off-vertical beams reveals a term that has not been included in mathematical formulas for spectral broadening in the past. This term arises from the simultaneous effects of the changing geometry due to curvature within a finite beamwidth and the vertical wind shear. The magnitude of this effect can be comparable to that of the well-known effects of beam-broadening and wind shear, and since it can have either algebraic sign, it can significantly reduce (or increase the expected spectral broadening, although under typical conditions it is smaller than the beam-broadening effect. The predictions of this simple model are found to be consistent with observations from the VHF radar at White Sands Missile Range, NM.

  15. Improving Enzyme Activity and Broadening Selectivity for Biological Desulfurization and Upgrading of Petroleum Feedstocks

    Energy Technology Data Exchange (ETDEWEB)

    Abhijeet P. Borole; Choo Y. Hamilton; Karen Miller; Brian Davison; Matthew Grossman; Robert Shong

    2003-05-12

    The objective of this project was to develop improved biocatalysts for desulfurization and upgrading of petroleum feedstocks. The goal was to improve the activity and broaden the selectivity of desulfurization enzymes using directed evolution as a tool as well as to explore the impact of ring-opening on biological desulfurization

  16. Effect of Doppler broadening on gain in an open V-type inversionless lasing system

    Institute of Scientific and Technical Information of China (English)

    Xijun Fan(樊锡君); Hui Xu(徐慧); Shufen Tian(田淑芬); Dianmin Tong(仝殿民)

    2004-01-01

    Our study shows that for the copropagating probing and driving fields, the gain without inversion doesn't monotonously decrease or increase with the increasement of Doppler width. When the driving field is resonant, at a suitable Doppler width, we can get a maximum value of the gain without inversion, which is much larger than that obtained when Doppler broadening is absent.

  17. Attitudes and Motivation of Poor and Good Spellers: Broadening Planned Behavior Theory

    Science.gov (United States)

    Sideridis, Georgios D.

    2005-01-01

    The purpose of the present study was to broaden planned behavior theory and examine its applicability to predict the academic achievement of students of low and high spelling ability. Two hundred fifty seven students, 54 low spellers and 203 high spellers from thirty elementary schools in northern Greece, participated in the study. Between groups…

  18. Broadening of Plasmonic Resonance Due to Electron Collisions with Nanoparticle Boundary: а Quantum Mechanical Consideration

    DEFF Research Database (Denmark)

    Uskov, Alexander; Protsenko, Igor E.; Mortensen, N. Asger;

    2014-01-01

    We present a quantum mechanical approach to calculate broadening of plasmonic resonances in metallic nanostructures due to collisions of electrons with the surface of the structure. The approach is applicable if the characteristic size of the structure is much larger than the de Broglie electron...

  19. Independent component analysis of inhomogeneous broadening in perturbed angular correlation spectroscopy

    Science.gov (United States)

    Stufflebeam, Michael; Hodges, Jeffery A.; Park, Tyler; Evenson, W.; Matheson, P.; Zacate, M. O.

    2008-10-01

    Independent component analysis (ICA) of electric field gradient (EFG) tensor components has proven useful in analysis of inhomogeneous broadening in perturbed angular correlation (PAC). We have simulated PAC spectra for various concentrations (0.1% to 15%) of randomly distributed defects with a near- neighbor vacancy in simple cubic and face-centered cubic crystal structures. In analyzing this simulation, we used ICA to transform the Vxx and Vzz EFG components to find a joint probability distribution function for the EFGs. ICA allowed us to separate the components and develop the joint probability function as a product of the probability distributions for two independent coordinates. Then we found the broadened G2(t) by integration over the joint probability distribution function. We have compared these results to simulated G2(t) functions, allowing us to analyze the concentration dependence of the broadened PAC spectrum. This work will be applied initially to broadened PAC data from β-Mn, Al-doped β-Mn, and Sr2RuO4.

  20. Broadening the definition of resilience and "reappraising" the use of appetitive motivation.

    Science.gov (United States)

    Soenke, Melissa; O'Connor, Mary-Frances; Greenberg, Jeff

    2015-01-01

    Kalisch et al.'s PASTOR model synthesizes current knowledge of resilience, focusing on mechanisms as a common pathway to outcomes and highlighting neuroscience as a method for exploring this. We propose the model broaden its definition of resiliency to include positive indices of recovery, include positive affect as a mechanism, and approach motivation as distinct from overcoming aversive motivation. PMID:26785906

  1. PROBLEM DEPENDENT DOPPLER BROADENING OF CONTINUOUS ENERGY CROSS SECTIONS IN THE KENO MONTE CARLO COMPUTER CODE

    Energy Technology Data Exchange (ETDEWEB)

    Hart, S. W. D. [University of Tennessee, Knoxville (UTK); Maldonado, G. Ivan [University of Tennessee, Knoxville (UTK); Celik, Cihangir [ORNL; Leal, Luiz C [ORNL

    2014-01-01

    For many Monte Carlo codes cross sections are generally only created at a set of predetermined temperatures. This causes an increase in error as one moves further and further away from these temperatures in the Monte Carlo model. This paper discusses recent progress in the Scale Monte Carlo module KENO to create problem dependent, Doppler broadened, cross sections. Currently only broadening the 1D cross sections and probability tables is addressed. The approach uses a finite difference method to calculate the temperature dependent cross-sections for the 1D data, and a simple linear-logarithmic interpolation in the square root of temperature for the probability tables. Work is also ongoing to address broadening theS (alpha , beta) tables. With the current approach the temperature dependent cross sections are Doppler broadened before transport starts, and, for all but a few isotopes, the impact on cross section loading is negligible. Results can be compared with those obtained by using multigroup libraries, as KENO currently does interpolation on the multigroup cross sections to determine temperature dependent cross-sections. Current results compare favorably with these expected results.

  2. PULSE BROADENING MEASUREMENTS FROM THE GALACTIC CENTER PULSAR J1745-2900

    Energy Technology Data Exchange (ETDEWEB)

    Spitler, L. G.; Lee, K. J.; Eatough, R. P.; Kramer, M.; Karuppusamy, R.; Desvignes, G.; Champion, D. J.; Falcke, H. [Max-Planck-Institut für Radioastronomie, Bonn D-53121 (Germany); Bassa, C. G.; Lyne, A. G.; Stappers, B. W. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, M13, 9PL Manchester (United Kingdom); Cognard, I. [Laboratoire de Physique et Chimie de l' Environnement et de l' Espace LPC2E CNRS-Université d' Orléans, F-45071 Orléans Cedex 02, and Station de radioastronomie de Nançay, Observatoire de Paris, CNRS/INSU, F-18330 Nançay (France); Bower, G. C. [UC Berkeley Astronomy Department, B-20 Hearst Field Annex, Berkeley, CA 94720-3411 (United States); Cordes, J. M. [Department of Astronomy and Space Sciences, Cornell University, Ithaca, NY 14853 (United States)

    2014-01-01

    We present temporal scattering measurements of single pulses and average profiles of PSR J1745-2900, a magnetar recently discovered only 3 arcsec away from Sagittarius A* (Sgr A*), from 1.2 to 18.95 GHz using the Effelsberg 100 m Radio Telescope, the Nançay Decimetric Radio Telescope, and the Jodrell Bank Lovell Telescope. Single pulse analysis shows that the integrated pulse profile above 2 GHz is dominated by pulse jitter, while below 2 GHz the pulse profile shape is dominated by scattering. This is the first object in the Galactic center (GC) with both pulse broadening and angular broadening measurements. We measure a pulse broadening time scale at 1 GHz of τ{sub 1GHz} = 1.3 ± 0.2 and pulse broadening spectral index of α = –3.8 ± 0.2, which is several orders of magnitude lower than predicted by the NE2001 model (Cordes and Lazio 2002). If this scattering time scale is representative of the GC as a whole, then previous surveys should have detected many pulsars. The lack of detections implies either our understanding of scattering in the GC is incomplete or there are fewer pulsars in the GC than previously predicted. Given that magnetars are a rare class of radio pulsar, there are likely many canonical and millisecond pulsars in the GC, and not surprisingly, scattering in the GC is spatially complex.

  3. Control of Polarization Interference in Doppler Broadened Two-Photon Resonant Four-Wave Mixing System

    Institute of Scientific and Technical Information of China (English)

    ZUO Zhan-Chun; LIU Xia; SUN Jiang; WU Ling-An; FU Pan-Ming

    2006-01-01

    @@ We study two-photon resonant nondegenerate four-wave mixing (NFWM) in a Doppler broadened system. It is found that because the induced polarization is sensitive to the atomic velocity, there exists interference between polarizations of atoms with different velocities, leading to significant modification of the NFWM spectra. This polarization interference can be controlled through applying an additional coupling field.

  4. Spectrally resolved four-wave mixing in semiconductors: Influence of inhomogeneous broadening

    DEFF Research Database (Denmark)

    Erland, J.; Pantke, K.-H.; Mizeikis, V.;

    1994-01-01

    We study the influence of inhomogeneous broadening on results obtained from spectrally resolved transient four-wave mixing. In particular, we study the case where more resonances are coherently excited, leading to polarization interference or quantum beats, depending on the microscopic nature...

  5. Kramers-Kronig relation in a Doppler-broadenedΛ-type three-level system

    Institute of Scientific and Technical Information of China (English)

    王梦; 庞兆广; 王如泉; 左战春; 芦小刚; 白金海; 裴丽娅; 缪兴绪; 高艳磊; 吴令安; 傅盘铭; 杨世平

    2015-01-01

    We measure the absorption and dispersion in a Doppler-broadenedΛ-type three level system by resonant stimulated Raman spectroscopy with homodyne detection. Through studying the dressed state energies of the system, it is found that the absorption and dispersion satisfy the Kramers–Kronig relation. The absorption and dispersion spectra calculated by employing this relation agree well with our experimental observations.

  6. High-energy pulse compressor using self-defocusing spectral broadening in anomalously dispersive media

    DEFF Research Database (Denmark)

    Bache, Morten; Zhou, Binbin

    2014-01-01

    A new high-energy pulse compressor uses self-defocusing spectral broadening in anomalously dispersive quadratic nonlinear crystals, followed by positive group-delay-dispersion compensation. Compression to sub-50 fs is possible from Joule-class 1.03 µm femtosecond amplifiers in large-aperture KDP....

  7. Spectral signatures of x((5)) processes in four-wave mixing of homogeneously broadened excitons

    DEFF Research Database (Denmark)

    Langbein, W.; Meier, T.; Koch, S.W.;

    2001-01-01

    The influence of fifth-order coherences on the spectrally resolved four-wave mixing response of predominantly homogeneously broadened quasi-two-dimensional excitons is studied. Fifth-order signatures are discussed as a function of spectral position and excitation polarization. An exciton-biexcito...

  8. Broaden Engineering Technology students' knowledge through hands-on with motion robotics

    Science.gov (United States)

    The skills and knowledge that employers value most are not always well-aligned with undergraduate engineering technology programs. With the support of a federal grant, we identify and propose to broaden the undergraduate student experience to include training in transferable skills with agricultura...

  9. Coupling and ionization effects on hydrogen spectral line shapes in dense plasmas

    Science.gov (United States)

    Calisti, A.; Bureyeva, L. A.; Lisitsa, V. S.; Shuvaev, D.; Talin, B.

    2007-06-01

    A study of hydrogen lines emitted in dense and low temperature plasmas is presented. Coupling and ionization effects in a transition from impact to quasi-static broadening for electrons are analyzed with the help of the Frequency Fluctuation Model (FFM). Electron broadening of Balmer series lines is studied for different densities and temperatures spanning a wide domain from impact to quasi-static limit. It is shown that electronic broadening makes a transition from impact to quasi-static limit depending on plasma conditions and principal quantum number. Even for the Balmer alpha line, at a density equals 1018 cm-3 and a temperature equals 1 eV, this transition occurs both in the wings and the core of the line.

  10. Broadening-free SBS-based slow and fast light in optical fibers

    Science.gov (United States)

    Schneider, Thomas; Wiatrek, Andrzej

    2013-03-01

    To change the group velocity of optical signals has a lot of possible applications in telecommunications, sensing, nonlinear optics and so on. Especially the exploitation of the effect of stimulated Brillouin scattering (SBS) in optical fibers is of special interest since it just requires standard telecom equipment and low to moderate optical power. However, each delay in one single, low-gain SBS based slow-light system is accompanied by pulse broadening. This is a result of the inherent Kramers-Kronig relations between the gain, the phase-change and the accompanied group velocity. For an ideal flat gain the phase-change is non-ideal, and for an ideal phase-change the gain curve leads to a broadening. Furthermore, if the gain bandwidth is broadened in order to adapt it to the signal, the delay will be reduced. Thus, for one single low-gain slow-light system the broadening can be reduced by several methods but it cannot be zero. Here we will show how a zero-broadening SBS based slow-light system can be achieved by two different methods. The basic idea is a reshaping of the original pulse by an adapted gain in a second stage. This adaptation is achieved by the superposition of two Gaussian gain profiles or by a single saturated gain. As will be shown, these systems show an almost ideal over-all gain and phase function over the bandwidth of the pulses. Thus, SBS based slow-light with a delaybandwidth product of more than 1 bit and zero distortion is possible.

  11. Stark Broadening of Carbon and Oxygen Lines in Hot DQ White Dwarf Stars: Recent Results and Applications

    OpenAIRE

    Dufour, P.; Nessib, N. Ben; Sahal-Bréchot, S.; Dimitrijević, M. S.

    2011-01-01

    White dwarf stars are traditionally found to have surface compositions made primarily of hydrogen or helium. However, a new family has recently been uncovered, the so-called Hot DQ white dwarfs, which have surface compositions dominated by carbon and oxygen with little or no trace of hydrogen and helium (Dufour et al. 2007, 2008, 2010). Deriving precise atmospheric parameters for these objects (such as the effective temperature and the surface gravity) requires detailed modeling of spectral l...

  12. Mixed Weyl Symbol Calculus and Spectral Line Shape Theory

    OpenAIRE

    Osborn, T. A.; Kondrat'eva, M. F.; Tabisz, G. C.; McQuarrie, B. R.

    1998-01-01

    A new and computationally viable full quantum version of line shape theory is obtained in terms of a mixed Weyl symbol calculus. The basic ingredient in the collision--broadened line shape theory is the time dependent dipole autocorrelation function of the radiator-perturber system. The observed spectral intensity is the Fourier transform of this correlation function. A modified form of the Wigner--Weyl isomorphism between quantum operators and phase space functions (Weyl symbols) is introduc...

  13. Measurement of Plasma Ion Temperature and Flow Velocity from Chord-Averaged Emission Line Profile

    Indian Academy of Sciences (India)

    Xu Wei

    2011-03-01

    The distinction between Doppler broadening and Doppler shift has been analysed, the differences between Gaussian fitting and the distribution of chord-integral line shape have also been discussed. Local ion temperature and flow velocity have been derived from the chord-averaged emission line profile by a chosen-point Gaussian fitting technique.

  14. Broadening the Study of Participation in the Life Sciences: How Critical Theoretical and Mixed-Methodological Approaches Can Enhance Efforts to Broaden Participation.

    Science.gov (United States)

    Metcalf, Heather

    2016-01-01

    This research methods Essay details the usefulness of critical theoretical frameworks and critical mixed-methodological approaches for life sciences education research on broadening participation in the life sciences. First, I draw on multidisciplinary research to discuss critical theory and methodologies. Then, I demonstrate the benefits of these approaches for researchers who study diversity and inclusion issues in the life sciences through examples from two critical mixed-methods studies of prominent issues in science, technology, engineering, and mathematics (STEM) participation and recognition. The first study pairs critical discourse analysis of the STEM workforce literature, data, and underlying surveys with quantitative analyses of STEM pathways into the workforce. This example illustrates the necessity of questioning popular models of retention. It also demonstrates the importance of intersecting demographic categories to reveal patterns of experience both within and between groups whose access to and participation in STEM we aim to improve. The second study's critical approach applies research on inequities in prizes awarded by STEM professional societies toward organizational change. This example uses data from the life sciences professional societies to show the importance of placing data within context to broaden participation and understand challenges in creating sustainable change. PMID:27521238

  15. A tunable dual-broad-band branch-line coupler utilizing composite right/left-handed transmission lines

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yu; HU Li; HE Sai-ling

    2005-01-01

    A tunable dual-broad-band branch-line coupler (BLC) utilizing composite right/left-handed (CRLH) transmission lines is presented. Two λ/4 segments consisting of CRLH transmission lines are added to each port to broaden the dual bands of the branch-line coupler. Numerical simulation and optimal design of the novel coupler are presented. The dual bands of the novel coupler are tunable and broad. The 1-dB bandwidth of each passband is more than 16% of the central frequency.

  16. Creation of Coherent Superposition States in Inhomogeneously Broadened Media with Relaxation

    CERN Document Server

    Sandor, N; Sörlei, Zs; Djotyan, G P

    2011-01-01

    We propose and analyze a scheme for "on demand" creation of coherent superposition of meta-stable states in a tripod-structured atom using frequency-chirped laser pulses. Negligible excitation of the atoms during the creation of the superposition states is a priority in our consideration. The underlying physics of the scheme is explained using the formalism of adiabatic states. By numerically solving master equation for the density matrix operator, we analyze the influence of the spontaneous decay and transverse relaxation on the efficiency of the creation of superposition states. We show that the proposed scheme is robust against small-to-medium variations of the parameters of the laser pulses. We provide a detailed analysis of the effect of the inhomogeneous (Doppler-) broadening on the efficiency of the coherence creation and show that the proposed scheme may be equally efficient in both homogeneously and Doppler-broadened media.

  17. ABSORPTION PROPERTIES OF A DRIVEN FOUR-LEVEL DOPPLER-BROADENED SYSTEM

    Institute of Scientific and Technical Information of China (English)

    YUAN SHI; WU JIN-HUI; GAO JIN-YUE

    2001-01-01

    This paper deals with the absorption spectra of a weak probe in a four-level Doppler-broadened system driven by three coherent fields. The main aim is to extend earlier studies of the spontaneous emission spectrum and to present a comprehensive survey of the spectral features of this system. In addition to a derivation of exact formulae for the spectra, we give an explanation with the help of an appropriate set of dressed atomic states. We also get a deeper insight into the physical origin of gain in view of the existence of a population inversion between the levels of the lasing transition. Finally, we explore the effect of Doppler broadening on the absorption profile of the weak probe.

  18. Quantification of tip-broadening in non-contact atomic force microscopy with carbon nanotube tips

    DEFF Research Database (Denmark)

    Meinander, Kristoffer; Jensen, Thomas N.; Simonsen, Soren B.;

    2012-01-01

    Carbon nanotube terminated atomic force microscopy (AFM) probes have been used for the imaging of 5 nm wide surface supported Pt nanoclusters by non-contact (dynamic mode) AFM in an ultra-high vacuum. The results are compared to AFM measurements done with conventional Si-tips, as well...... as with transmission electron microscopy images, which give accurate measures for cluster widths. Despite their ideal aspect ratio, tip-broadening is concluded to be a severe problem even when imaging with carbon nanotube tips, which overestimates the cluster width by several times the nominal width of the nanotube...... tip. This broadening is attributed to a bending of the carbon nanotubes, and not to pure geometrical factors, which coincidentally results in a significant improvement for relative height measurements of tightly spaced high aspect ratio structures, as compared to what can be achieved...

  19. Impact of echo broadening effect on active range-gated imaging

    Institute of Scientific and Technical Information of China (English)

    Xinwei Wang; Yan Zhou; Yuliang Liu

    2012-01-01

    Analytical formulas and experimental proof of the echo broadening effect in active range-gated imaging,including atmospheric interference,currently exist.We investigate the impact of this effect on target detection.Our research demonstrates that the echo broadening effect affects the energy profile of the depth of view and collects only part of the signals of targets in head and tail zones.Under bad weather conditions,the effect weakens the signal-to-noise ratio (SNR) of images,especially in cases with large laser pulse width.Fortunately,by modifying the laser pulse width,the effect can be controlled.These results are valuable to the applications of active range-gated imaging.

  20. Broadening participation in Natural Sciences and Mathematics at the University of Maryland Baltimore County

    Science.gov (United States)

    Rous, Philip

    2013-03-01

    Over the past two decades, UMBC has undertaken a series of efforts to broaden participation in the natural sciences and mathematics, beginning with the establishment of the Meyerhoff program. Using as examples the multiple initiatives that followed, and with a focus on the challenge of increasing access and success of all students who enter as both freshmen and transfer students, I will describe a model of culture change that we have employed repeatedly to understand and guide our efforts in broadening participation. Particular attention will be paid to the concept of cultural capital, the role of innovators and the challenge of scaling small-scale innovations towards institutional change. Supported by the National Science Foundation and the Bill and Melinda Gates Foundation.

  1. In-medium jet evolution: interplay between broadening and decoherence effects

    CERN Document Server

    Apolinário, Liliana; Milhano, Guilherme; Salgado, Carlos A

    2015-01-01

    The description of the modifications of the coherence pattern in a parton shower, in the presence of a QGP, has been actively addressed in recent studies. Among the several achievements, finite energy corrections, transverse momentum broadening due to medium interactions and interference effects between successive emissions have been extensively improved as they seem to be essential features for a correct description of the results obtained in heavy-ion collisions. In this work, based on the insights of our previous work [1], we explore the physical interplay between broadening and decoherence, by generalising previous studies of medium-modifications of the antenna spectrum [2, 3, 4] - so far restricted to the case where transverse motion is neglected. The result allow us to identify two quantities controlling the decoherence of a medium modified shower that can be used as building blocks for a successful future generation of jet quenching Monte Carlo simulators: a generalisation of the $\\Delta_{med}$ paramet...

  2. Dielectric spectra broadening as the signature of dipole-matrix interaction. II. Water in ionic solutions.

    Science.gov (United States)

    Levy, Evgeniya; Puzenko, Alexander; Kaatze, Udo; Ben Ishai, Paul; Feldman, Yuri

    2012-03-21

    In this, the second part of our series on the dielectric spectrum symmetrical broadening of water, we consider ionic aqueous solutions. If in Part I, dipole-dipole interaction was the dominant feature, now ion-dipole interplay is shown to be the critical element in the dipole-matrix interaction. We present the results of high-frequency dielectric measurements of different concentrations of NaCl/KCl aqueous solutions. We observed Cole-Cole broadening of the main relaxation peak of the solvent in the both electrolytes. The 3D trajectory approach (described in detail in Part I) is applied in order to highlight the differences between the dynamics and structure of solutions of salts on one hand and dipolar solutes on the other hand.

  3. From discrete to continuous the broadening of number concepts in early modern England

    CERN Document Server

    Neal, Katherine

    2002-01-01

    In the early modern period, a crucial transformation occurred in the classical conception of number and magnitude. Traditionally, numbers were merely collections of discrete units that measured some multiple. Magnitude, on the other hand, was usually described as being continuous, or being divisible into parts that are infinitely divisible. This traditional idea of discrete number versus continuous magnitude was challenged in the early modern period in several ways. This detailed study explores how the development of algebraic symbolism, logarithms, and the growing practical demands for an expanded number concept all contributed to a broadening of the number concept in early modern England. An interest in solving practical problems was not, in itself, enough to cause a generalisation of the number concept. It was the combined impact of novel practical applications together with the concomitant development of such mathematical advances as algebraic notation and logarithms that produced a broadened number conce...

  4. Dielectric spectra broadening as the signature of dipole-matrix interaction. II. Water in ionic solutions.

    Science.gov (United States)

    Levy, Evgeniya; Puzenko, Alexander; Kaatze, Udo; Ben Ishai, Paul; Feldman, Yuri

    2012-03-21

    In this, the second part of our series on the dielectric spectrum symmetrical broadening of water, we consider ionic aqueous solutions. If in Part I, dipole-dipole interaction was the dominant feature, now ion-dipole interplay is shown to be the critical element in the dipole-matrix interaction. We present the results of high-frequency dielectric measurements of different concentrations of NaCl/KCl aqueous solutions. We observed Cole-Cole broadening of the main relaxation peak of the solvent in the both electrolytes. The 3D trajectory approach (described in detail in Part I) is applied in order to highlight the differences between the dynamics and structure of solutions of salts on one hand and dipolar solutes on the other hand. PMID:22443773

  5. Four-wave mixing at maximum coherence and eliminated Doppler broadening controlled with the driving fields

    CERN Document Server

    Popov, A K; George, T F; Shalaev, V M; Bayev, Alexander S.; George, Thomas F.; Shalaev, Vladimir M.

    2000-01-01

    New feasibity of coherent quantum control of four-wave mixing processes in a resonant Doppler-broadened medium are studied. We propose a technique which enables one to enhance the quantum efficiency of nonlinear optical conversion. At the same time, it allows one to decrease the required intensities of the fundamental beams compared to those necessary in the approach based on coherent population trapping. The major outcomes of the analysis are illustrated with numerical simulation addressed within a practical medium.

  6. Comparative Study on Beam Broadening in Optically Controlled and Conventional Phased Array

    Institute of Scientific and Technical Information of China (English)

    GAO Yu-xiang; HE Zi-shu; XU Ji-lin; HAN Chun-lin

    2005-01-01

    The bandwidth characteristic of phased array antenna can be represented by the extent of beam broadening as signal bandwidth is increased. By using two kinds of bandpass signals, the beam 3dB-width values for a variety of instantaneous bandwidths in conventional phased array and wide band optically phased array are respectively analyzed and simulated based on both of their models. And some corresponding curves are given.

  7. Power broadening and Doppler effects of coherent dark resonances in Rb

    Science.gov (United States)

    Erhard, Michael; Nußmann, Stefan; Helm, Hanspeter

    2000-12-01

    Using a phase-locked laser pair we have observed dark resonances with linewidths below 30 Hz in a rubidium cell filled with neon as buffer gas. A model allowing for pressure broadening correctly reproduces the dependence of the width on the laser intensity. Consideration of velocity changing collisions reveals the absence of Doppler effects in the position and width of the dark resonance at high buffer-gas pressure.

  8. Doppler broadening effect on collision cross section functions - Deconvolution of the thermal averaging

    Science.gov (United States)

    Bernstein, R. B.

    1973-01-01

    The surprising feature of the Doppler problem in threshold determination is the 'amplification effect' of the target's thermal energy spread. The small thermal energy spread of the target molecules results in a large dispersion in relative kinetic energy. The Doppler broadening effect in connection with thermal energy beam experiments is discussed, and a procedure is recommended for the deconvolution of molecular scattering cross-section functions whose dominant dependence upon relative velocity is approximately that of the standard low-energy form.

  9. The broadening spectrum of reputation risk in organizations: banking on risk and trust relationships

    OpenAIRE

    Scott, Susan V.; Walsham, Geoff

    2004-01-01

    Globalizing knowledge economies foster conditions that intensify the role and value of organizational reputation risk. In a holistic, enterprise focused era reputation is a key strategic construct that can act as a boundary object linking communities within and between organizations. Yet approaches to its management tend to be reactive and remain under the hold of industrial society principles. In this paper we examine the influences fuelling a broadening in the spectrum of organizational ...

  10. Inhomogeneous broadening of PAC spectra with V zz and η joint probability distribution functions

    Science.gov (United States)

    Evenson, W. E.; Adams, M.; Bunker, A.; Hodges, J.; Matheson, P.; Park, T.; Stufflebeam, M.; Zacate, M. O.

    2013-05-01

    The perturbed angular correlation (PAC) spectrum, G 2( t), is broadened by the presence of randomly distributed defects in crystals due to a distribution of electric field gradients (EFGs) experienced by probe nuclei. Heuristic approaches to fitting spectra that exhibit such inhomogeneous broadening (ihb) consider only the distribution of EFG magnitudes V zz , but the physical effect actually depends on the joint probability distribution function (pdf) of V zz and EFG asymmetry parameter η. The difficulty in determining the joint pdf leads us to more appropriate representations of the EFG coordinates, and to express the joint pdf as the product of two approximately independent pdfs describing each coordinate separately. We have pursued this case in detail using as an initial illustration of the method a simple point defect model with nuclear spin I = 5/2 in several cubic lattices, where G 2( t) is primarily induced by a defect trapped in the first neighbor shell of a probe and broadening is due to defects distributed at random outside the first neighbor shell. Effects such as lattice relaxation are ignored in this simple test of the method. The simplicity of our model is suitable for gaining insight into ihb with more than V zz alone. We simulate ihb in this simple case by averaging the net EFGs of 20,000 random defect arrangements, resulting in a broadened average G 2( t). The 20,000 random cases provide a distribution of EFG components which are first transformed to Czjzek coordinates and then further into the full Czjzek half plane by conformal mapping. The topology of this transformed space yields an approximately separable joint pdf for the EFG components. We then fit the nearly independent pdfs and reconstruct G 2( t) as a function of defect concentration. We report results for distributions of defects on simple cubic, face-centered cubic, and body-centered cubic lattices. The method explored here for analyzing ihb is applicable to more realistic cases.

  11. Infantile nystagmus syndrome: Broadening the high-foveation-quality field with contact lenses

    Directory of Open Access Journals (Sweden)

    Giovanni Taibbi

    2008-10-01

    Full Text Available Giovanni Taibbi1,4,5, Zhong I Wang1,3, Louis F Dell’Osso1–31The Daroff-Dell’Osso Ocular Motility Laboratory, Louis Stokes Cleveland Department of Veterans Affairs Medical Center and CASE Medical School; 2Department of Neurology; 3Department of Biomedical Engineering, Case Western Reserve University and University Hospitals Case Medical Center, Cleveland, OH, USA; 4Pediatric Ophthalmology and Strabismus Unit, San Paolo Hospital, Milan, Italy; 5University of Milan, Milan, ItalyAbstract: We investigated the effects of contact lenses in broadening and improving the high-foveation-quality field in a subject with infantile nystagmus syndrome (INS. A high-speed, digitized video system was used for the eye-movement recording. The subject was asked to fixate a far target at different horizontal gaze angles with contact lenses inserted. Data from the subject while fixating at far without refractive correction and at near (at a convergence angle of 60 PD, were used for comparison. The eXpanded Nystagmus Acuity Function (NAFX was used to evaluate the foveation quality at each gaze angle. Contact lenses broadened the highfoveation-quality range of gaze angles in this subject. The broadening was comparable to that achieved during 60 PD of convergence although the NAFX values were lower. Contact lenses allowed the subject to see “more” (he had a wider range of high-foveation-quality gaze angles and “better” (he had improved foveation at each gaze angle. Instead of being contraindicated by INS, contact lenses emerge as a potentially important therapeutic option. Contact lenses employ afferent feedback via the ophthalmic division of the V cranial nerve to damp INS slow phases over a broadened range of gaze angles. This supports the proprioceptive hypothesis of INS improvement.Keywords: contact lenses, infantile nystagmus, visual function

  12. Pressure broadening of the ((dt. mu. )dee)/sup */ formation resonances

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, J.S.; Leon, M.; Padial, N.T.

    1988-01-01

    The treatment of ((dt..mu..)dee)/sup */ formation at high densities as a pressure broadening process is discussed. The quasistatic approximation is shown to satisfy the usual conditions of muon-catalyzed fusion better than does the impact approximation. Complete accurate results are shown for the impact approximation, and a preliminary rough treatment is presented to illustrate the quasistatic approximation. 13 refs., 8 figs.

  13. Broadening the scope of Open Innovation: Introduction to the special issue

    OpenAIRE

    Van de Vrande, Vraeska; Vanhaverbeke,Wim; Gassmann, Oliver

    2010-01-01

    In this first paper of the special issue, we identify some trends in open innovation research by analysing how the literature on this topics has evolved since the introduction of the concept in 2003. Research on open innovation has been mushrooming ever since and the scope has been broadened in different directions. Researchers also started to analyse open innovation at different level of analysis from the individual actors in organisations to ecosystems and national innovation systems. Despi...

  14. Broadening the scope of open innovation : past research, current state and future directions

    OpenAIRE

    Van de Vrande, Vareska; Vanhaverbeke,Wim; Gassmann, Oliver

    2010-01-01

    In this first paper of the special issue, we identify some trends in open innovation research by analysing how the literature on this topics has evolved since the introduction of the concept in 2003. Research on open innovation has been mushrooming ever since and the scope has been broadened in different directions. Researchers also started to analyse open innovation at different level of analysis from the individual actors in organisations to ecosystems and national innovation systems. Despi...

  15. Broadly tunable resonant Raman gain and cw lasing in an optically thick Doppler-broadened medium

    Science.gov (United States)

    Popov, Alexander K.; Myslivets, Sergei A.; Hinze, Ulf; Tiemann, E.; Wellegehausen, Bernd; Tartakovsky, Gennady

    1999-09-01

    Interactive numerical simulator, based on MATLAB/SIMULINK platform, for virtual experimentation and optimization of frequency tunable optically pumped dimer laser has been created. Nonperturbative theory considering features of quantum coherence and interference effects at Doppler broadened transitions under two strong driving fields accounting for collisions and other kinetic processes in vapor-gas mixture as well as for propagation effects in optically thick medium is developed. The results are in good agreement with real experiments.

  16. Pressure broadening of the [(dtμ)dee]/sup */ formation resonances

    International Nuclear Information System (INIS)

    The treatment of [(dtμ)dee]/sup */ formation at high densities as a pressure broadening process is discussed. The quasistatic approximation is shown to satisfy the usual conditions of muon-catalyzed fusion better than does the impact approximation. Complete accurate results are shown for the impact approximation, and a preliminary rough treatment is presented to illustrate the quasistatic approximation. 13 refs., 8 figs

  17. Turbulence in Clusters of Galaxies and X-Ray Line Profiles

    CERN Document Server

    Inogamov, N A

    2003-01-01

    Large-scale bulk motions and hydrodynamic turbulence in the intergalactic gas inside clusters of galaxies significantly broaden X-ray emission lines. For lines of heavy ions (primarily helium-like and hydrogen-like iron ions), the hydrodynamic broadening is significantly larger than the thermal broadening. Since cluster of galaxies have a negligible optical depth for resonant scattering in forbidden and intercombination lines of these ions, these lines are not additionally broadened. At the same time, they are very intense, which allows deviations of the spectrum from the Gaussian spectrum in the line wings to be investigated. The line shape becomes an important indicator of bulk hydrodynamic processes because the cryogenic detectors of new generation of X-ray observatories will have a high energy resolution (from 5 eV for ASTRO-E2 to 1-2 eV for Constellation-X and XEUS). We use the spectral representation of a Kolmogorov cascade in the inertial range to calculate the characteristic shapes of X-ray lines. Sig...

  18. Overcoming Experimental and Intrinsic Broadening in Excited State Spectroscopies using Richardson-Lucy Deconvolution

    Science.gov (United States)

    Elam, W. T.; Fister, T. T.; Seidler, G. T.; Nagle, K. P.; Kas, J. J.; Cross, J. O.

    2007-03-01

    The oscillatory signature of the photoelectron interference phenomenon central to core shell spectroscopies is frequently broadened by experimental or intrinsic (i.e., core-hole lifetime) energy resolutions, limiting the interpretation of the measurement. For example, this problem occurs in x-ray absorption fine structure (XAFS) measurements of heavy elements where the core-hole lifetime is very short (/τcore-hole>=5,eV), and also in non-resonant x-ray Raman scattering measurements where the instrumental resolution (typically ˜1 eV) can be nearly an order of magnitude larger than the intrinsic energy resolution. Given the small statistical uncertainties in typical XAFS data and in recent XRS measurements using dedicated multielement spectrometers, the question naturally arises as to deconvolving the data with respect to the known instrumental or intrinsic resolutions. Here, we demonstrate that the Richardson-Lucy iterative algorithm provides a robust maximum likelihood method for addressing this issue in both XAFS and XRS. We demonstrate this method on core-hole broadened Ag XAFS data and experimentally broadened diamond and graphite XRS data.

  19. On the origin of the scatter broadening of fast radio burst pulses and astrophysical implications

    CERN Document Server

    Xu, Siyao

    2016-01-01

    Fast radio bursts (FRBs) have been identified as extragalactic sources which can make a probe of turbulence in the intergalactic medium (IGM) and their host galaxies. To account for the observed millisecond pulses caused by scatter broadening, we examine a variety of possible models of electron density fluctuations in both the IGM and the host galaxy medium. We find that a shallow power-law spectrum of density, which may arise in highly supersonic turbulence with pronounced local dense structures of shock-compressed gas in the host interstellar medium (ISM), can produce the required density enhancements at sufficiently small scales to interpret the scattering timescale of FRBs. It implies that an FRB residing in a galaxy with efficient star formation in action tends to have a broadened pulse. The scaling of the scattering time with dispersion measure (DM) in the host galaxy varies in different turbulence and scattering regimes. The host galaxy can be the major origin of scatter broadening, but contribute to a...

  20. Proton Lateral Broadening Distribution Comparisons Between GRNTRN, MCNPX, and Laboratory Beam Measurements

    Science.gov (United States)

    Mertens, Christopher J.; Moyers, Michael F.; Walker, Steven A.; Tweed, John

    2010-01-01

    Recent developments in NASA s deterministic High charge (Z) and Energy TRaNsport (HZETRN) code have included lateral broadening of primary ion beams due to small-angle multiple Coulomb scattering, and coupling of the ion-nuclear scattering interactions with energy loss and straggling. This new version of HZETRN is based on Green function methods, called GRNTRN, and is suitable for modeling transport with both space environment and laboratory boundary conditions. Multiple scattering processes are a necessary extension to GRNTRN in order to accurately model ion beam experiments, to simulate the physical and biological-effective radiation dose, and to develop new methods and strategies for light ion radiation therapy. In this paper we compare GRNTRN simulations of proton lateral broadening distributions with beam measurements taken at Loma Linda University Proton Therapy Facility. The simulated and measured lateral broadening distributions are compared for a 250 MeV proton beam on aluminum, polyethylene, polystyrene, bone substitute, iron, and lead target materials. The GRNTRN results are also compared to simulations from the Monte Carlo MCNPX code for the same projectile-target combinations described above.

  1. Gamma-ray emission spectrum from thermonuclear fusion reactions without intrinsic broadening

    DEFF Research Database (Denmark)

    Nocente, M.; Källne, J.; Salewski, Mirko;

    2015-01-01

    First principle calculations of the gamma-ray energy spectrum arising from thermonuclear reactions without intrinsic broadening in fusion plasmas are presented, extending the theoretical framework needed to interpret measurements up to the accuracy level enabled by modern high resolution instrume......First principle calculations of the gamma-ray energy spectrum arising from thermonuclear reactions without intrinsic broadening in fusion plasmas are presented, extending the theoretical framework needed to interpret measurements up to the accuracy level enabled by modern high resolution...... results based on a Monte Carlo method are provided, focusing in particular on improved relations between the peak shift and width from the reaction and the temperature of protons accelerated by radio-frequency heating.The results presented in this paper significantly improve the accuracy of diagnostic...... information that can be extracted from the gamma-ray emission spectrum of fusion reactions without intrinsic broadening and are of relevance for applications to high performance plasmas of present and next generation devices....

  2. Magnetic excitations and anomalous spin-wave broadening in multiferroic FeV2O4

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Qiang [Ames Laboratory; Ramazanoglu, Mehmet [Ames Laboratory; Chi, Songxue [Oak Ridge National Laboratory; Liu, Yong [Ames Laboratory; Lograsso, Thomas A. [Ames Laboratory; Vaknin, David [Ames Laboratory

    2014-06-01

    We report on the different roles of two orbital-active Fe2+ at the A site and V3+ at the B site in the magnetic excitations and on the anomalous spin-wave broadening in FeV2O4. FeV2O4 exhibits three structural transitions and successive paramagnetic (PM)–collinear ferrimagnetic (CFI)–noncollinear ferrimagnetic (NCFI)/ferroelectric transitions. The high-temperature tetragonal/PM–orthorhombic/CFI transition is accompanied by the appearance of a large energy gap in the magnetic excitations due to strong spin-orbit-coupling-induced anisotropy at the Fe2+ site. While there is no measurable increase in the energy gap from the orbital ordering of V3+ at the orthorhombic/CFI–tetragonal/NCFI transition, anomalous spin-wave broadening is observed in the orthorhombic/CFI state due to V3+ spin fluctuations at the B site. The spin-wave broadening is also observed at the zone boundary without softening in the NCFI/ferroelectric phase, which is discussed in terms of magnon-phonon coupling. Our study also indicates that the Fe2+ spins without the frustration at the A site may not play an important role in inducing ferroelectricity in the tetragonal/NCFI phase of FeV2O4.

  3. Spectral broadening induced by intense ultra-short pulse in 4H–SiC crystals

    Science.gov (United States)

    Chun-hua, Xu; Teng-fei, Yan; Gang, Wang; Wen-jun, Wang; Jing-kui, Liang; Xiao-long, Chen

    2016-06-01

    We report the observation of spectral broadening induced by 200 femtosecond laser pulses with the repetition rate of 1 kHz at the wavelength of 532 nm in semi-insulating 4H–SiC single crystals. It is demonstrated that the full width at half maximum of output spectrum increases linearly with the light propagation length and the peak power density, reaching a maximum 870 cm‑1 on a crystal of 19 mm long under an incident laser with a peak power density of 60.1 GW/cm2. Such spectral broadening can be well explained by the self-phase modulation model which correlates time-dependent phase change of pulses to intensity-dependent refractive index. The nonlinear refractive index n 2 is estimated to be 1.88×10‑15 cm2/W. The intensity-dependent refractive index is probably due to both the nonlinear optical polarizability of the bound electrons and the increase of free electrons induced by the two-photon absorption process. Super continuum spectra could arise as crystals are long enough to induce the self-focusing effect. The results show that SiC crystals may find applications in spectral broadening of high power lasers. Project supported by the National High Technology Research and Development Program of China (Grant No. 2014AA041402) and the National Natural Science Foundation of China (Grant Nos. 51272276 and 51322211).

  4. Water vapor line parameters from 6450 to 9400 cm−1

    International Nuclear Information System (INIS)

    The spectra of natural water vapor were recorded in the spectral range 6450–9400 cm−1 with a step-by-step Fourier transform spectrometer at room temperature with absorption path lengths up to 1200 m. Positions, intensities and self-broadening coefficients of about 11,000 lines were determined. This paper focuses on the intensity parameters: the lines of four isotopologues H216O, H218O, H217O and HD16O were observed and assigned; it presents a new experimental dataset in the 6450–9400 cm−1 spectral range. Obtained results were compared to the literature data. Fifty-nine new and corrected energy levels of H216O and H217O were determined from the vibration–rotation analysis of the observed lines. A brief discussion is added for self-broadening coefficients at the end of this paper. - Highlights: • New water vapor spectra recorded by FT Spectroscopy from 6450 to 9400 cm-1. • Retrieval of line parameters by multispectrum fitting procedure at room temperature. • Comparison of the line intensity measurements with data found in the literature. • Preliminary study of measured self-broadening coefficients

  5. Pressure effects on water vapour lines: beyond the Voigt profile.

    Science.gov (United States)

    Ngo, N H; Tran, H; Gamache, R R; Hartmann, J M

    2012-06-13

    A short overview of recent results on the effects of pressure (collisions) regarding the shape of isolated infrared lines of water vapour is presented. The first part of this study considers the basic collisional quantities, which are the pressure-broadening and -shifting coefficients, central parameters of the Lorentzian (and Voigt) profile and thus of any sophisticated line-shape model. Through comparisons of measured values with semi-classical calculations, the influences of the molecular states (both rotational and vibrational) involved and of the temperature are analysed. This shows the relatively unusual behaviour of H(2)O broadening, with evidence of a significant vibrational dependence and the fact that the broadening coefficient (in cm(-1) atm(-1)) of some lines increases with temperature. In the second part of this study, line shapes beyond the Voigt model are considered, thus now taking 'velocity effects' into account. These include both the influence of collisionally induced velocity changes that lead to the so-called Dicke narrowing and the influence of the dependence of collisional parameters on the speed of the radiating molecule. Experimental evidence of deviations from the Voigt shape is presented and analysed. The interest of classical molecular dynamics simulations, to model velocity changes, together with semi-classical calculations of the speed-dependent collisional parameters for line-shape predictions from 'first principles', are discussed. PMID:22547229

  6. Universal Representation of the H-like Spectral Line Shapes

    Science.gov (United States)

    Bureyeva, L.

    2009-05-01

    A universal approach for the calculation of Rydberg atom line shapes in plasmas is developed. It is based on analytical formulas for the intensity distribution in radiation transitions n→n' between highly excited atomic states with large values of principal quantum numbers n, n'≫1, with Δ n = n-n'≪n, and on the Frequency Fluctuation Model (FFM) to account of electron and ion thermal motion effects. The theory allows to describe a transition from the static to the impact broadening domains for every hydrogen spectral line. A new approach to extremely fast line shape calculations with account of charged particle dynamic effect was proposed. The approach is based on the close analogy between the static-impact broadening transition in the spectral line shape theory and the Doppler-Lorentz broadening in the Dicke narrowing effect theory. The precision of the new approach was tested by the comparison of hydrogen-alpha and beta line shapes calculations with the FFM results. The excellent agreement was discovered, the computer time decreased two orders of magnitudes as compared with the FFM.

  7. Measurements of NH3 linestrengths and collisional broadening coefficients in N2, O2, CO2, and H2O near 1103.46cm-1

    KAUST Repository

    Owen, Kyle

    2013-05-01

    Laser-based ammonia gas sensors have useful applications in many fields including combustion, atmospheric monitoring, and medical diagnostics. Calibration-free trace gas sensors require the spectroscopic parameters including linestrengths and collisional broadening coefficients to be known. Ammonia\\'s strong ν2 vibrational band between 9 - 12 μm has the high absorption strength needed for sensing small concentrations. Within this band, the 1103.46cm-1 feature is one of the strongest and has minimal interference from CO2 and H2O. However, the six rotational transitions that make up this feature have not been studied previously with absorption spectroscopy due to their small line spacing ranging from 0.004 to 0.029cm-1. A tunable quantum cascade laser was used to accurately study these six transitions. A retrieval program was used to determine the linestrengths and collisional broadening coefficients based on Voigt and Galatry profiles. The experiments were performed with ammonia mixtures in nitrogen, oxygen, water vapor, and carbon dioxide at room temperature in an optical cell. These data are going to aid in the development of quantitative ammonia sensors utilizing this strong absorption feature. © 2013 Elsevier Ltd.

  8. The IACOB project: IV. New predictions for high-degree non-radial mode instability domains in massive stars and connection with macroturbulent broadening

    CERN Document Server

    Godart, M; Herrero, A; Dupret, M A; Grötsch-Noels, A; Salmon, S J A J; Ventura, P

    2016-01-01

    Asteroseismology is a powerful tool to access the internal structure of stars. Apart from the important impact of theoretical developments, progress in this field has been commonly associated with the analysis of time-resolved observations. Recently, the so-called macroturbulent broadening has been proposed to be a complementary and less expensive way -- in terms of observational time -- to investigate pulsations in massive stars. We assess to what extent this ubiquitous non-rotational broadening component shaping the line profiles of O stars and B supergiants is a spectroscopic signature of pulsation modes driven by a heat mechanism. We compute stellar main sequence and post-main sequence models from 3 to 70Msun with the ATON stellar evolution code and determine the instability domains for heat-driven modes for degrees l=1-20 using the adiabatic and non-adiabatic codes LOSC and MAD. We use the observational material presented in Sim\\'on-D\\'iaz et al. (2016) to investigate possible correlations between the si...

  9. N2- and (H2+He)-broadened cross sections of benzene (C6H6) in the 7-15 μm region for the Titan and jovian atmospheres

    Science.gov (United States)

    Sung, Keeyoon; Toon, Geoffrey C.; Crawford, Timothy J.

    2016-06-01

    In support of atmospheric remote sensing of Titan and jovian planets, we measured absorption cross sections of benzene (C6H6) in the 7-15 μm region at temperatures between 235 K and 297 K. For this, high-resolution laboratory spectra of C6H6 were obtained using two cold cells (80 cm and 2.07 cm path length) configured to a high resolution Fourier-transform infrared (FT-IR) spectrometer, Bruker IFS-125HR, at the Jet Propulsion Laboratory (JPL). The spectrum sets include 15 pure and 15 N2-broadened benzene spectra in the 630-1534 cm-1 region, along with four additional spectra broadened by an H2(85%) and He(15%) gas mixture for the 630-740 cm-1 region. From these spectra, temperature dependent benzene cross sections were obtained for gas phase benzene in the presence of N2 and (H2+He) at ambient pressures and temperatures down to 235 K. In addition, we generated two independent sets of pseudolines: one of N2-broadened benzene for Titan and the other of (H2+He)-broadened benzene for jovian planets. It is shown that the benzene pseudolines can reproduce the observed features to ˜ 5% in transmittance, including the continuum-like absorption formed by numerous overlapping weak and hot band transitions. Based on the pseudoline parameters, the integrated band intensities at 296 K for the three strongest bands in the region were measured to be 177.0(73), 14.0(10), 27.2(9)×10-17 cm-1/(molecule·cm-2) in the region of v4 at 674 cm-1, v14 at 1038.267, and v13 at 1483.985 cm-1, respectively, from the combined set of pure and N2-broadened benzene spectra. For the (H2+He) mixture-broadened benzene spectra, the integrated band intensity for v4 band in the 630-735 cm-1 region was measured to be 168.8(17)×10-17 cm-1/(molecule·cm-2) at 296 K, which is in agreement with the intensity derived from the N2-broadened benzene spectra within the combined measurement uncertainties. The results from this work show an excellent agreement (2%) with one of the latest experimental studies by

  10. High Line

    OpenAIRE

    Jagielska, Anna

    2015-01-01

    This project examines The High Line in New York City and what is due to its success. The park, which runs through the meatpacking district in Manhattan, is on an old rail line that was abandoned from the 1980s. Two private locals, Joshua and Hammond, founded the non-profit organization “Friends of The High Line” and established the rail line into a public park. The aesthetics of the park is the wildness of the nature and the modern architecture in the middle of Manhattan mixed with a sustaina...

  11. Collisional shifts and broadenings of the 4sns {sup 1}S{sub 0} and 4snd {sup 1}D{sub 2} Rydberg series of calcium perturbed by inert gases

    Energy Technology Data Exchange (ETDEWEB)

    Marafi, M; Afrousheh, K; Makdisi, Y; Suji, Z; Mathew, J [Department of Physics, Kuwait University, PO Box 5969, 13060 Safat (Kuwait)], E-mail: marafim@kuc01.kuniv.edu.kw

    2009-07-28

    An excimer pumped dye laser was used to measure collisional shift and broadening rates of the nd {sup 1}D{sub 2} (n = 4-50) and ns {sup 1}S{sub 0} series (n = 5-30) of calcium Rydberg states. Two-photon absorption techniques were used to populate the Rydberg states. High-resolution Ca excitation spectra were measured using a diode detector while scanning the frequency of the dye laser. Inert gases Ar, Kr and Xe were used as perturbers at pressures of 100 mbar. Shifts and broadenings of spectral lines were measured as functions of the principal quantum number n. The pressure-dependence behaviour of the 4s63d {sup 1}D{sub 2} Rydberg state as well as its configuration interactions is discussed.

  12. Spectral line parameters including line shapes in the 2ν3 Q branch of 12CH4

    Science.gov (United States)

    Devi, V. Malathy; Benner, D. Chris; Sung, Keeyoon; Brown, Linda R.; Crawford, Timothy J.; Yu, Shanshan; Smith, Mary Ann H.; Mantz, Arlan W.; Boudon, Vincent; Ismail, Syed

    2016-07-01

    In this study, we report the first experimental measurements of spectral line shape parameters (self- and air-broadened Lorentz half-widths, pressure-shifts, and line mixing (via off-diagonal relaxation matrix elements) coefficients and their temperature dependences, where appropriate) for transitions in the 2ν3 Q branch manifolds, Q(11)-Q(1) of methane (12CH4), in the 5996.5-6007-cm-1 region. The analysis included 23 high-resolution, high signal-to-noise laboratory absorption spectra recorded with the Bruker IFS-125HR Fourier transform spectrometer (FTS) at JPL. The experimental data were obtained using 12C-enriched 12CH4 and dilute mixtures of 12CH4 in dry air in the 130-296 K range using a room-temperature long path absorption cell and, two custom-built coolable cells. In the analysis, an interactive multispectrum fitting software was employed where all the 23 spectra (11 self-broadened and 12 air-broadened) were fit simultaneously. By carefully applying reasonable constraints to the parameters for severely blended lines, we were able to determine a self-consistent set of broadening, shift and line mixing (relaxation matrix coefficients) parameters for CH4-CH4 and CH4-air collisions. In the majority of cases, a quadratic speed dependence parameter common for all transitions in each Q(J) manifold was determined. However, temperature dependences of the Q branch line mixing parameter could not be determined from the present data. Since no other experimental line shape measurements have been reported for this Q-branch, the present results are compared to available values in the HITRAN2012 database.

  13. Blurring lines

    OpenAIRE

    Howard, Heidi C; Knoppers, Bartha Maria; Borry, Pascal

    2010-01-01

    Companies that offer direct-to-consumer genetic testing and conduct research are blurring the line between customers and research subjects. Should these companies adhere to the same ethical regulations as academic researchers?

  14. High Line

    DEFF Research Database (Denmark)

    Kiib, Hans

    2015-01-01

    At just over 10 meters above street level, the High Line extends three kilometers through three districts of Southwestern Manhattan in New York. It consists of simple steel construction, and previously served as an elevated rail line connection between Penn Station on 34th Street and the many....... The High Line project has been carried out as part of an open conversion strategy. The result is a remarkable urban architectural project, which works as a catalyst for the urban development of Western Manhattan. The greater project includes the restoration and reuse of many old industrial buildings...... in close proximity to the park bridge and new projects being added to fit the context. The outcome is a conglomeration of non-contemporary urban activities along the High Line, where mechanical workshops, small wholesale stores. etc. mix with new exclusive residential buildings, eminent cafés...

  15. Seyfert 2 galaxies with unusually wide nebular lines

    CERN Document Server

    Winkler, Hartmut

    2014-01-01

    We report on a set of AGN that match the Seyfert 2 galaxy classification criteria, but display unusually wide "narrow" lines, with the 4959 {\\AA} and 5007 {\\AA} nebular lines overlapping with each other. This spectral line broadening is in most cases evidence of a complex profile with multiple components. It indicates an unusual narrow line region with diverse gas clouds and a range of velocity systems. We list 14 such objects with these characteristics identified in a set of Sloan Digital Sky Survey spectra. We measure the strengths of all lines visible in the spectrum, and attempt to fit multiple Gaussian profiles to the nebular lines. We quantify the line parameters of all multiple velocity systems discovered. We compare the spectral characteristics of our sample with those of other, 'conventional' type 2 Seyferts and attempt to determine whether other systematic spectral differences exist. We consider whether the investigated sample constitutes a clear sub-class of the Seyfert 2 population. In conclusion ...

  16. PUMPING UP THE [N I] NEBULAR LINES

    Energy Technology Data Exchange (ETDEWEB)

    Ferland, G. J.; Porter, R. L. [Department of Physics, University of Kentucky, Lexington, KY 40506 (United States); Henney, W. J. [Centro de Radioastronomia y Astrofisica, UNAM Campus Morelia, Apartado Postal 3-72, 58090 Morelia, Michoacan (Mexico); O' Dell, C. R. [Department of Physics and Astronomy, Vanderbilt University, Box 1807-B, Nashville, TN 37235 (United States); Van Hoof, P. A. M. [Royal Observatory of Belgium, Ringlaan 3, 1180 Brussels (Belgium); Williams, R. J. R. [AWE plc, Aldermaston, Reading RG7 4PR (United Kingdom)

    2012-09-20

    The optical [N I] doublet near 5200 A is anomalously strong in a variety of emission-line objects. We compute a detailed photoionization model and use it to show that pumping by far-ultraviolet (FUV) stellar radiation previously posited as a general explanation applies to the Orion Nebula (M42) and its companion M43; but, it is unlikely to explain planetary nebulae and supernova remnants. Our models establish that the observed nearly constant equivalent width of [N I] with respect to the dust-scattered stellar continuum depends primarily on three factors: the FUV to visual-band flux ratio of the stellar population, the optical properties of the dust, and the line broadening where the pumping occurs. In contrast, the intensity ratio [N I]/H{beta} depends primarily on the FUV to extreme-ultraviolet ratio, which varies strongly with the spectral type of the exciting star. This is consistent with the observed difference of a factor of five between M42 and M43, which are excited by an O7 and B0.5 star, respectively. We derive a non-thermal broadening of order 5 km s{sup -1} for the [N I] pumping zone and show that the broadening mechanism must be different from the large-scale turbulent motions that have been suggested to explain the line widths in this H II region. A mechanism is required that operates at scales of a few astronomical units, which may be driven by thermal instabilities of neutral gas in the range 1000-3000 K. In an Appendix A, we describe how collisional and radiative processes are treated in the detailed model N I atom now included in the CLOUDY plasma code.

  17. PUMPING UP THE [N I] NEBULAR LINES

    International Nuclear Information System (INIS)

    The optical [N I] doublet near 5200 Å is anomalously strong in a variety of emission-line objects. We compute a detailed photoionization model and use it to show that pumping by far-ultraviolet (FUV) stellar radiation previously posited as a general explanation applies to the Orion Nebula (M42) and its companion M43; but, it is unlikely to explain planetary nebulae and supernova remnants. Our models establish that the observed nearly constant equivalent width of [N I] with respect to the dust-scattered stellar continuum depends primarily on three factors: the FUV to visual-band flux ratio of the stellar population, the optical properties of the dust, and the line broadening where the pumping occurs. In contrast, the intensity ratio [N I]/Hβ depends primarily on the FUV to extreme-ultraviolet ratio, which varies strongly with the spectral type of the exciting star. This is consistent with the observed difference of a factor of five between M42 and M43, which are excited by an O7 and B0.5 star, respectively. We derive a non-thermal broadening of order 5 km s–1 for the [N I] pumping zone and show that the broadening mechanism must be different from the large-scale turbulent motions that have been suggested to explain the line widths in this H II region. A mechanism is required that operates at scales of a few astronomical units, which may be driven by thermal instabilities of neutral gas in the range 1000-3000 K. In an Appendix A, we describe how collisional and radiative processes are treated in the detailed model N I atom now included in the CLOUDY plasma code.

  18. Voigt-function modeling in Fourier analysis of size- and strain-broadened X-ray diffraction peaks

    Energy Technology Data Exchange (ETDEWEB)

    Balzar, D.; Ledbetter, H. (Materials Science and Engineering Lab., National Inst. of Standards and Technology, Boulder, CO (United States))

    1993-02-01

    With the assumption that both size- and strain-broadened profiles of the pure-specimen function are described with a Voigt function, it is shown that the analysis of Fourier coefficients leads to the Warren-Averbach method of separation of size and strain contributions. The analysis of size coefficients shows that the 'hook' effect occurs when the Cauchy content of the size-broadened profile is underestimated. The ratio of volume-weighted and surface-weighted domain sizes can change from [proportional to]1.31, for the minimum allowed Cauchy content, to 2, when the size-broadened profile is given solely by a Cauchy function. If the distortion coefficient is approximated by a harmonic term, mean-square strains decrease linearly with increasing the averaging distance. The local strain is finite only in the case of purely Gaussian strain broadening, because strains are then independent of averaging distance. (orig.).

  19. Numerical quantification of the vibronic broadening of the SrTiO3 Ti L-edge spectrum

    Science.gov (United States)

    Gilmore, Keith; Shirley, Eric

    2010-03-01

    Calculations of x-ray absorption spectra are typically limited to obtaining the positions and intensities of spectral features, while simply adding broadening artificially to match experimental results. However, spectral widths hold valuable information on the coupling of the notional excited electronic state with the environment. The 2p^53d^1 excited state of the Ti^4+ ion in SrTiO3 experiences Jahn-Teller coupling to eg distortions of the oxygen cage. Such coupling broadens the electronic transition by involving a variable number of eg phonons. We quantify this broadening effect by solving a model Hamiltonian, taking parameters for the Hamiltonian from first-principles calculations. Comparison of numerical and experimental results indicates that this vibronic coupling accounts for the majority of the broadening observed for the L3-edge, but only a minority of the L2-edge spectral width.

  20. Broadening engineering education: bringing the community in : commentary on "social responsibility in French engineering education: a historical and sociological analysis".

    Science.gov (United States)

    Conlon, Eddie

    2013-12-01

    Two issues of particular interest in the Irish context are (1) the motivation for broadening engineering education to include the humanities, and an emphasis on social responsibility and (2) the process by which broadening can take place. Greater community engagement, arising from a socially-driven model of engineering education, is necessary if engineering practice is to move beyond its present captivity by corporate interests.

  1. Broadening engineering education: bringing the community in : commentary on "social responsibility in French engineering education: a historical and sociological analysis".

    Science.gov (United States)

    Conlon, Eddie

    2013-12-01

    Two issues of particular interest in the Irish context are (1) the motivation for broadening engineering education to include the humanities, and an emphasis on social responsibility and (2) the process by which broadening can take place. Greater community engagement, arising from a socially-driven model of engineering education, is necessary if engineering practice is to move beyond its present captivity by corporate interests. PMID:24072611

  2. Elastic LO-phonon scattering as an efficient mechanism of dephasing and homogeneous broadening in quantum dots

    DEFF Research Database (Denmark)

    Uskov, Alexander V.; Tromborg, Bjarne; Jauho, Antti-Pekka;

    2000-01-01

    The spectral linewidth of optical transitions in quantum dots is shown to be strongly broadened by elastic scattering of LO phonons on the confined carriers. The scattering does not excite the carriers but results in a large dephasing rate.......The spectral linewidth of optical transitions in quantum dots is shown to be strongly broadened by elastic scattering of LO phonons on the confined carriers. The scattering does not excite the carriers but results in a large dephasing rate....

  3. Spectral broadening and temporal compression of 100 fs pulses in air-filled hollow core capillary fibers,

    OpenAIRE

    C. Li; Rishad, K.P.M.; Horak, P.; Matsuura, Y.; Faccio, D

    2014-01-01

    We experimentally study the spectral broadening of intense, ~100 femtosecond laser pulses at 785 nm coupled into different kinds of hollow core capillary fibers, all filled with air at ambient pressure. Differently from observations in other gases, the spectra are broadened with a strong red-shift due to highly efficient intrapulse Raman scattering. Numerical simulations show that such spectra can be explained only by increasing the Raman fraction of the third order nonlinearity close to 100%...

  4. Detection of Voigt Spectral Line Profiles of Hydrogen Radio Recombination Lines toward Sagittarius B2(N)

    CERN Document Server

    von Prochazka, Azrael A; Balser, Dana S; Ryans, Robert S I; Marshall, Adele H; Schwab, Fredric R; Hollis, Jan M; Jewell, Philip R; Lovas, Frank J

    2010-01-01

    We report the detection of Voigt spectral line profiles of radio recombination lines (RRLs) toward Sagittarius B2(N) with the 100-m Green Bank Telescope (GBT). At radio wavelengths, astronomical spectra are highly populated with RRLs, which serve as ideal probes of the physical conditions in molecular cloud complexes. An analysis of the Hn(alpha) lines presented herein shows that RRLs of higher principal quantum number (n>90) are generally divergent from their expected Gaussian profiles and, moreover, are well described by their respective Voigt profiles. This is in agreement with the theory that spectral lines experience pressure broadening as a result of electron collisions at lower radio frequencies. Given the inherent technical difficulties regarding the detection and profiling of true RRL wing spans and shapes, it is crucial that the observing instrumentation produce flat baselines as well as high sensitivity, high resolution data. The GBT has demonstrated its capabilities regarding all of these aspects,...

  5. Line formation in solar granulation; 1, Fe line shapes, shifts and asymmetries

    CERN Document Server

    Asplund, M; Trampedach, R; Allende-Prieto, C; Stein, R F; Nordlund, AA.

    2000-01-01

    Realistic ab-initio 3D, radiative-hydrodynamical convection simulations of the solar granulation have been applied to FeI and FeII line formation. In contrast to classical analyses based on hydrostatic 1D model atmospheres the procedure contains no adjustable free parameters but the treatment of the numerical viscosity in the construction of the 3D, time-dependent, inhomogeneous model atmosphere and the elemental abundance in the 3D spectral synthesis. However, the numerical viscosity is introduced purely for numerical stability purposes and is determined from standard hydrodynamical test cases with no adjustments allowed to improve the agreement with the observational constraints from the solar granulation. The non-thermal line broadening is mainly provided by the Doppler shifts arising from the convective flows in the solar photosphere and the solar oscillations. The almost perfect agreement between the predicted temporally and spatially averaged line profiles for weak Fe lines with the observed profiles an...

  6. Characterization of film surface treated with ECR plasma by Doppler broadening

    CERN Document Server

    Nishijima, S; Hirata, K; Kobayashi, Y; Honda, Y; Tagawa, S

    2000-01-01

    Doppler broadened positron annihilation measurements were carried out using the positron beam technique on plasma treated polyethylene films as a function of incident positron energy. In addition, surface properties of the treated films also have been measured using other conventional techniques such as FT-IR, SEM and AFM. The surface tension of the films was also determined using sessile drop method. The S-parameter is seen to decrease on the surface upon plasma treatment that introduces polar groups such as hydroxyl and carbonyl on the surface. The results are discussed.

  7. Stretchable polymeric modulator for intracavity spectroscopic broadening of femtosecond optical parametric oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yimeng; Zhang, Xinping, E-mail: Zhangxinping@bjut.edu.cn; Zhang, Jian; Liu, Hongmei [Institute of Information Photonics Technology and College of Applied Sciences, Beijing University of Technology, Beijing 100124 (China)

    2014-07-07

    We investigate stretching-induced microscopic deformations spatially distributed in a flexible plate of polydimethylsiloxane (PDMS) and their applications in the broadening of the output spectrum of a femtosecond optical parametric oscillator. The hologram of the stretched PDMS plate was used to evaluate indirectly the microscopic deformations. The experimental results show that these deformations exhibit weak scattering and diffraction of light and induce negligible cavity loss, ensuring practical applications of the PDMS plate as an intracavity device for lasers. In combination with the thickness reduction of the PDMS plate through stretching, the distributed deformations enable smooth tuning of the output spectrum.

  8. Broadening and attenuation of UV laser ablation plumes in background gases

    DEFF Research Database (Denmark)

    Amoruso, S.; Toftmann, B.; Schou, Jørgen

    2005-01-01

    -of-flight distribution with a Langmuir probe. The angular distribution broadens for all gases except for a minor pressure range for the helium background gas, in which a distinct plume narrowing occurs. The behavior of the collected, ablated silver atoms integrated over the full hemisphere is similar for all gases....... This integral decreases strongly above a characteristic pressure, which depends on the specific gas. The ion time-of-flight signal shows a clear plume splitting into a fast and a slow component except for the ablation plume in a helium gas. (c) 2005 Elsevier B.V. All rights reserved....

  9. A technique to study the mechanisms of pressure broadening of spectral holes

    International Nuclear Information System (INIS)

    An experimental procedure to distinguish between the two possible mechanisms (dispersive and diffusive) of pressure broadening of spectral holes in nonisobaric experiments is proposed. The method makes use of nonlinear saturation properties of the hole burning process. The proposed four-step procedure consists of burning a hole, applying hydrostatic pressure to the system, additional burning at the hole minimum at this second pressure, and then applying more pressure. By model calculations it is demonstrated that, under certain conditions, the dispersive mechanism yields a double-minimum hole, while the diffusive mechanism does not. Experimental observability of such an effect is discussed. (author)

  10. Broadening of axial neutron flux difference operating band in Angra I

    International Nuclear Information System (INIS)

    ANGRA I Technical Specifications requires the axial flux difference to remain within ± 5 percent band, relative to a reference value, for any power level. The reference value is the axial flux difference at a 100% power, all rods (almost) out and equilibrium Xenon distribution. This paper presents the results of several Simulations, performed by FURNAS staff aiming the validation of calculation results against the reload designer's ones. It was also proved that the Axial Flux Difference Operating band can be broadened to ''Ref. +- 6.9% ) without exce eding the limit imposed by the ''envelope-curve''. (author)

  11. Vacancy type defect formation in irradiated α-iron investigated by positron beam Doppler broadening technique

    International Nuclear Information System (INIS)

    Vacancy type defects formations have been investigated in virgin and irradiated a-iron samples using slow positron beam Doppler broadening technique. Mono-vacancies and vacancy clusters are observed in 1.5 MeV 4He ions irradiated Fe samples at varying fluences from 1×1013 to 1×1017 cm−2. In the 1.2 MeV Yttrium ions implantation at low fluence 1×1014 cm−2 vacancy clusters with higher concentration and larger size are formed. In this sample, vacancy defects are detected deeper than predicted by SRIM calculation due to channelling.

  12. Stretchable polymeric modulator for intracavity spectroscopic broadening of femtosecond optical parametric oscillators

    Science.gov (United States)

    Wang, Yimeng; Zhang, Xinping; Zhang, Jian; Liu, Hongmei

    2014-07-01

    We investigate stretching-induced microscopic deformations spatially distributed in a flexible plate of polydimethylsiloxane (PDMS) and their applications in the broadening of the output spectrum of a femtosecond optical parametric oscillator. The hologram of the stretched PDMS plate was used to evaluate indirectly the microscopic deformations. The experimental results show that these deformations exhibit weak scattering and diffraction of light and induce negligible cavity loss, ensuring practical applications of the PDMS plate as an intracavity device for lasers. In combination with the thickness reduction of the PDMS plate through stretching, the distributed deformations enable smooth tuning of the output spectrum.

  13. The variable temperature pressure broadening and pressure shift of CO in collision with helium

    International Nuclear Information System (INIS)

    Pressure broadening and pressure shift parameters have been measured for CO in collision with helium over a wide range of temperatures. This temperature range includes the high temperature semiclassical regime in which the physics of the collision is properly described by Anderson-like theories as well as the low temperature regime in which new phenomena associated with quasibound states require a more complete quantum mechanical description. Experimental results will be compared to theoretical predictions generated from a variety of CO-He potential energy surfaces. The discrepancy between experiment and the best available potential energy surface will be discussed

  14. Quantum Memory for Microwave Photons in an Inhomogeneously Broadened Spin Ensemble

    DEFF Research Database (Denmark)

    Julsgaard, Brian; Grezes, Cécile; Bertet, Patrice;

    2013-01-01

    We propose a multi-mode quantum memory protocol able to store the quantum state of the field in a microwave resonator into an ensemble of electronic spins. The stored information is protected against inhomogeneous broadening of the spin ensemble by spin-echo techniques resulting in memory times...... orders of magnitude longer than previously achieved. By calculating the evolution of the first and second moments of the spin-cavity system variables for realistic experimental parameters, we show that a memory based on NV center spins in diamond can store a qubit encoded on the |0> and |1> Fock states...

  15. The Need for a National Alliance for Broadening Participation of Native Americans in the Geosciences.

    Science.gov (United States)

    Dalbotten, D. M.

    2008-12-01

    The continuing underrepresentation of Native Americans in the Geosciences can only mean that Native voices go unheard in setting research agendas and priorities. This is particularly significant where issues such as global climate change impact the land and livelihood of Native American communities. This talk will outline the need for a national alliance for broadening participation of Native Americans in the Geosciences. Our focus will be on defining goals for this alliance, i.e., new research in Geoscience education, defining best practices, inclusion of Native voices in Geoscience research, the potential for new collaborations, and promotion of opportunities for Native students and communities.

  16. Absorption properties of a driven Doppler-broadened ladder system with hyperfine structure

    Institute of Scientific and Technical Information of China (English)

    吴金辉; 高锦岳

    2002-01-01

    We have studied the absorption spectrum of a Doppler-broadened ladder system, where the highest level is coupled into two middle hyperfine sublevels by a strong coherent field. We find that, when the system is considered as homoge- neous, either two or three spectral components are observed, depending on the detuning of the coherent field. But when the velocity distribution of atoms is considered, we can always observe one electromagnetically induced transparency (EIT) window with high dispersion. So the atomic hyperfine structure cannot be an impediment for obtaining EIT.

  17. Kramers-Kronig relation in a Doppler-broadened Λ-type three-level system

    Science.gov (United States)

    Wang, Meng; Lu, Xiao-Gang; Bai, Jin-Hai; Pei, Li-Ya; Miao, Xing-Xu; Gao, Yan-Lei; Wu, Ling-An; Fu, Pan-Ming; Yang, Shi-Ping; Pang, Zhao-Guang; Wang, Ru-Quan; Zuo, Zhan-Chun

    2015-11-01

    We measure the absorption and dispersion in a Doppler-broadened Λ-type three level system by resonant stimulated Raman spectroscopy with homodyne detection. Through studying the dressed state energies of the system, it is found that the absorption and dispersion satisfy the Kramers-Kronig relation. The absorption and dispersion spectra calculated by employing this relation agree well with our experimental observations. Project supported by the National Basic Research Program of China (Grant Nos. 2013CB922002 and 2010CB922904), the National Natural Science Foundation of China (Grant Nos. 11274376 and 61308011), and the Natural Science Foundation of Hebei Province, China (Grant No. A2015205161).

  18. Scatter broadening of pulsars and implications on the interstellar medium turbulence

    CERN Document Server

    Xu, Siyao

    2016-01-01

    Observations reveal a uniform Kolmogorov turbulence throughout the diffuse ionized interstellar medium (ISM) and supersonic turbulence preferentially located in the Galactic plane. Correspondingly, we consider the Galactic distribution of electron density fluctuations consisting of not only a Kolmogorov density spectrum but also a short-wave-dominated density spectrum with the density structure formed at small scales due to shocks. The resulting dependence of the scatter broadening time on the dispersion measure (DM) naturally interprets the existing observational data for both low and high-DM pulsars. According to the criteria that we derive for a quantitative determination of scattering regimes over wide ranges of DMs and frequencies $\

  19. Broadening the Service Offering for Customers of University Properties of Finland

    OpenAIRE

    Rinne, Anita

    2013-01-01

    The background of this thesis is the commissioner’s, University Properties of Finland Ltd, who aim to find out the service needs of the University campus users. The company is developing and letting the campuses for Universities and their customers to use. It has a vision to make campuses lively UniverCities. This goal demands new services and service providers to come to the campuses. The aim of this thesis is to find out if there are possibilities to broaden the service offering in Uni...

  20. Thermal broadening of Lb band of ``trehalose coated'' tyrosine and phenylalanine

    Science.gov (United States)

    Carrotta, Rita; Sanfratello, Vincenzo; Leone, Maurizio; Cordone, Lorenzo

    2000-04-01

    We studied the thermal broadening of Lb band of tyrosine and phenylalanine embedded in a trehalose matrix. Aim of this work is to obtain information on the effects of "trehalose coating" on the coupling of the electronic transition to low frequency modes in the surrounding of the chromophore. The results obtained for the two molecular complexes put in evidence that O-H groups are involved in blocking these structures within the solid trehalose matrix and shed light on the role played by hydrogen bonds on the interactions that keep "trehalose coated" proteins rigid and solid-like.

  1. Gauge invariant formulation of the intracollisional field effect including collisional broadening

    International Nuclear Information System (INIS)

    A gauge-invariant formalism is presented for describing nonperturbatively the effects of the electric field on electron-phonon scattering in a nondegenerate semiconductor. The Kadanoff-Bayn nonequilibrium formulation of many-body systems is employed to treat the intracollisional field effect and collisional broadening on equal footing. We derive an analytic, gauge-invariant model for the spectral density function and for the density of energy states which accounts for both effects simultaneously in a relatively simple and rigorous way. (orig.)

  2. Laboratory measurement of H2O2 pressure broadening parameter for JEM/SMILES Observation from International Space Station

    Science.gov (United States)

    Sato, T.; Mizoguchi, A.; Kasai, Y.; Kanamori, H.

    2009-12-01

    A new generation of sub-millimeter-wave receivers employing sensitive SIS (Superconductor Insulator Superconductor) detector technology will provide new opportunities for precise remote sensing measurements of minor constituents in the earth and planetary atmosphere.Superconducting Sub-Millimeter-Wave Limb-Emission Sounder (SMILES) was designed to be onboard the Japanese Experiment Module (JEM) on the International Space Station (ISS) as a collaboration project of National Institute of Information and Communications Technology (NICT) and Japan Aerospace Exploration Agency (JAXA).SMILES in Transfer Vehicle (HTV) plan to launch in September 11 2009 by Japanese H-IIB rocket. JEM/SMILES will allow to observe the atmospheric species such as O3, H35Cl, H37Cl, ClO, BrO, HOCl, HO2, H2O2, HNO3 and CH3CN, Ozone isotope species, and water vapor with the precisions in a few to several tens percents [1] in the altitude region upper troposphere (about 8km in mid-latitude) and the mesosphere (about 90km in mid-latitude). In this paper, laboratory measurement of the pressure broadening parameter (γ) of Hydrogen peroxide (H2O2) at JKa,Kc = 201,19 - 192,17 rotational transition (625.044 GHz) will be presented. This is one of the target transitions of JEM/SMILES observation. γ of H2O2 in sub-millimeter-wave region was measured for the first time. The measurement was carried out using a sub-millimeter-wave absorption spectrometric system in Tokyo Institute of Technology.The radiation source from a backward wave oscillator (BWO) was phase-locked to the harmonics of a synthesized sweeper with two-step phase lock loop. The BWO source frequency was modulated with the modulation frequency of 51 kHz. H2O2 sample was prerpared by distillation of commercial available 30% solution. The pressures of sample and buffer gas (N2 and O2) were controlled by a mass flow meter and monitored by two Baratron monitors in the cell. From the observed profiles of the spectrum, the pressure broadening line

  3. SOLUTION DYNAMICS BY LINE-SHAPE ANALYSIS, RESONANCE LIGHT-SCATTERING AND FEMTOSECOND 4-WAVE-MIXING

    NARCIS (Netherlands)

    NIBBERING, ETJ; DUPPEN, K; WIERSMA, DA

    1992-01-01

    The results of line shape analysis, resonance light scattering and femtosecond four-wave mixing measurements are reported on several organic molecules in solution. It is shown that a Brownian oscillator model for line broadening provides a full description for the optical dynamics in aprotic solutio

  4. Temporal broadening of optical pulses propagating through non-Kolmogorov turbulence.

    Science.gov (United States)

    Chen, Chunyi; Yang, Huamin; Lou, Yan; Tong, Shoufeng; Liu, Rencheng

    2012-03-26

    General formulations of the temporal averaged pulse intensity for optical pulses propagating through either non-Kolmogorov or Kolmogorov turbulence are deduced under the strong fluctuation conditions and the narrow-band assumption. Based on these formulations, an analytical formula for the turbulence-induced temporal half-width of spherical-wave Gaussian (SWG) pulses is derived, and the single-point, two-frequency mutual coherence function (MCF) of collimated Gaussian-beam waves in atmospheric turbulence is formulated analytically, by which the temporal averaged pulse intensity of collimated space-time Gaussian (CSTG) pulses can be calculated numerically. Calculation results show that the temporal broadening of both SWG and CSTG pulses in atmospheric turbulence depends heavily on the general spectral index of the spatial power spectrum of refractive-index fluctuations, and the temporal broadening of SWG pulses can be used to approximate that of CSTG pulses on the axis with the same turbulence parameters and propagation distances. It is also illustrated by numerical calculations that the variation in the turbulence-induced temporal half-width of CSTG pulses with the radial distance is really tiny.

  5. Inversionless gain enhancing due to Doppler broadening in a closed lambda-type system

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    An analysis is made of the effect of Doppler broadening on gain without inversion (GWI) from different aspects in a closed lambda-type three-level system with an incoherent pump. It is shown that, regardless of the driving field being on resonance or not, for the counter- or co-propagating of the probe and driving fields (PDF), GWI does not monotonically decrease or increase with increasing Doppler width. Except for the case of counter-propagating PDF with off-resonance driving field, at a suitable Doppler width one can obtain a gain maximum value much larger than that without Doppler broadening; especially in the situation of the resonant driving field, the co-propagating geometry leads to a larger GWI. In addition, for the counter-propagating geometry, when Doppler width is larger enough, GWI oscillation occurs, and the oscillation amplitude and region increase with increasing Doppler width. These conclusions are very different from that obtained in previous investigation (Lukin et al, Laser Phys. 6 436 (1996)).

  6. Interactive effects of a quantitative and broadened interpretation of the double contingency principle

    International Nuclear Information System (INIS)

    Implementation of the Double Contingency Principle (DCP) for defense-in-depth depends upon measures taken to prevent single failure cause of a criticality accident. In previously published work, the Markov method was shown to be useful for analyzing concurrency, and the independence of changes in process conditions was shown to be expressible quantitatively in terms of a correlation coefficient. Also in previously published work, interpretation of the correlation coefficient was broadened to include the augmentations of negative-definite values and of non-commutativity. In addition, previously published work examined the precepts of reliability analysis and the precepts of correlation analysis to show that the well-trodden path of the former can lead to more perceptive implementation of the latter, while the broadening of the latter can introduce new pathways to the former. In this paper, interactive effects of quantitative assessments of the likelihood, independence, and concurrency aspects of the DCP are examined. When such interactive effects are considered, the quantitative approach becomes more complex, and the use of related approaches, such as reliability analysis, becomes more limited. An illustrative example of the augmentations introduced in previous work is shown with consideration of interactive effects. (authors)

  7. Broadening Participation of Women and Underrepresented Minorities in STEM through a Hybrid Online Transfer Program.

    Science.gov (United States)

    Drew, Jennifer C; Galindo-Gonzalez, Sebastian; Ardissone, Alexandria N; Triplett, Eric W

    2016-01-01

    The Microbiology and Cell Science (MCS) Department at the University of Florida (UF) developed a new model of a 2 + 2 program that uses a hybrid online approach to bring its science, technology, engineering, and mathematics (STEM) curriculum to students. In this paradigm, 2-year graduates transfer as online students into the Distance Education in MCS (DE MCS) bachelor of science program. The program has broadened access to STEM with a steadily increasing enrollment that does not draw students away from existing on-campus programs. Notably, half of the DE MCS students are from underrepresented minority (URM) backgrounds and two-thirds are women, which represents a greater level of diversity than the corresponding on-campus cohort and the entire university. Additionally, the DE MCS cohort has comparable retention and academic performance compared with the on-campus transfer cohort. Of those who have earned a BS through the DE MCS program, 71% are women and 61% are URM. Overall, these data demonstrate that the hybrid online approach is successful in increasing diversity and provides another viable route in the myriad of STEM pathways. As the first of its kind in a STEM field, the DE MCS program serves as a model for programs seeking to broaden their reach. PMID:27587859

  8. Broadening Participation of Women and Underrepresented Minorities in STEM through a Hybrid Online Transfer Program

    Science.gov (United States)

    Drew, Jennifer C.; Galindo-Gonzalez, Sebastian; Ardissone, Alexandria N.; Triplett, Eric W.

    2016-01-01

    The Microbiology and Cell Science (MCS) Department at the University of Florida (UF) developed a new model of a 2 + 2 program that uses a hybrid online approach to bring its science, technology, engineering, and mathematics (STEM) curriculum to students. In this paradigm, 2-year graduates transfer as online students into the Distance Education in MCS (DE MCS) bachelor of science program. The program has broadened access to STEM with a steadily increasing enrollment that does not draw students away from existing on-campus programs. Notably, half of the DE MCS students are from underrepresented minority (URM) backgrounds and two-thirds are women, which represents a greater level of diversity than the corresponding on-campus cohort and the entire university. Additionally, the DE MCS cohort has comparable retention and academic performance compared with the on-campus transfer cohort. Of those who have earned a BS through the DE MCS program, 71% are women and 61% are URM. Overall, these data demonstrate that the hybrid online approach is successful in increasing diversity and provides another viable route in the myriad of STEM pathways. As the first of its kind in a STEM field, the DE MCS program serves as a model for programs seeking to broaden their reach. PMID:27587859

  9. Inhomogeneously broadened fiber-amplifier cascades for transparent multiwavelength lightwave networks

    Science.gov (United States)

    Goldstein, E. L.; Eskildsen, L.; da Silva, V.; Andrejco, M.; Silberberg, Y.

    1995-05-01

    The emergence of practical fiber-amplifier chains has swiftly raised the prospect of transparent lightwave networks, in which signals travel from source to destination through a sequence of intermediate nodes without optoelectronic conversion. When such networks employ multiple wavelengths, however, some of the most substantial new research challenges are those posed by the amplifier chains themselves. Such networks suffer from accumulating interchannel power spread, from sensitivity to interamplifier loss variations, and from transient cross saturation, as the network undergoes reconfiguration. All of these difficulties effectively vanish in a chain of saturated lightwave amplifiers whose per-channel gains are decoupled by, e.g., inhomogeneous broadening. Unlike conventional, homogeneously broadened systems, saturated fiber-amplifier chains with decoupled gain dynamics provide automatic channel-by-channel power regulation, tolerance to interamplifier loss variations, and immunity to transient cross saturation. Thus, if amplifiers with such decoupled gain dynamics can be implemented in a practical way, they promise to solve - in a single stroke - several of the most substantial technological challenges facing transparent multiwavelength lightwave networks.

  10. Global wild annual Lens collection: a potential resource for lentil genetic base broadening and yield enhancement.

    Directory of Open Access Journals (Sweden)

    Mohar Singh

    Full Text Available Crop wild relatives (CWRs are invaluable gene sources for various traits of interest, yet these potential resources are themselves increasingly threatened by the impact of climate change as well as other anthropogenic and socio-economic factors. The prime goal of our research was to cover all aspects of wild Lens genetic resource management like species characterization, agro-morphological evaluation, diversity assessment, and development of representative sets for its enhanced utilization in lentil base broadening and yield improvement initiatives. We characterized and evaluated extensively, the global wild annual Lens taxa, originating from twenty seven counties under two agro-climatic conditions of India consecutively for three cropping seasons. Results on various qualitative and quantitative characters including two foliar diseases showed wide variations for almost all yield attributing traits including multiple disease resistance in the wild species, L. nigricans and L. ervoides accessions. The core set developed from the entire Lens taxa had maximum representation from Turkey and Syria, indicating rich diversity in accessions originating from these regions. Diversity analysis also indicated wide geographical variations across genepool as was reflected in the core set. Potential use of core set, as an initial starting material, for genetic base broadening of cultivated lentil was also suggested.

  11. Strong Blue Asymmetry in Hα Line as a Preflare Activity

    Science.gov (United States)

    Cho, Kyuhyoun; Lee, Jeongwoo; Chae, Jongchul; Wang, Haimin; Ahn, Kwangsu; Yang, Heesu; Lim, Eun-kyung; Maurya, Ram Ajor

    2016-10-01

    Chromospheric activities before solar flares provide important clues to the mechanisms that initiate solar flares, but are as yet poorly understood. We report a significant and rapid Hα line broadening before the solar flare SOL2011-09-29T18:08 that was detected using the unprecedented high-resolution Hα imaging spectroscopy with the Fast Imaging Solar Spectrograph (FISS) installed on the 1.6 m New Solar Telescope (NST) at Big Bear Solar Observatory. The strong Hα broadening extends as a blue excursion up to -4.5 Å and as a red excursion up to 2.0 Å, which implies a mixture of velocities in the range of -130 km s^{-1} to 38 km s-1 derived by applying the cloud model, comparable to the highest chromospheric motions reported before. The Hα blueshifted broadening lasts for about six minutes and is temporally and spatially correlated with the start of a rising filament, which is later associated with the main phase of the flare as detected by the Atmosphere Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO). The potential importance of this Hα blueshifted broadening as a preflare chromospheric activity is briefly discussed within the context of the two-step eruption model.

  12. Line facilities outline

    International Nuclear Information System (INIS)

    This book deals with line facilities. The contents of this book are outline line of wire telecommunication ; development of line, classification of section of line and theory of transmission of line, cable line ; structure of line, line of cable in town, line out of town, domestic cable and other lines, Optical communication ; line of optical cable, transmission method, measurement of optical communication and cable of the sea bottom, Equipment of telecommunication line ; telecommunication line facilities and telecommunication of public works, construction of cable line and maintenance and Regulation of line equipment ; regulation on technique, construction and maintenance.

  13. Diagnostic Technique of Neutron Doppler Broadening for Indirectly-Driven Implosions

    Institute of Scientific and Technical Information of China (English)

    熊勇; 丁永坤; 郑志坚; 陈铭

    2004-01-01

    The neutron Doppler broadening in inertial confinement fusion has been acquired from the time of flight for the neutron, from which the fuel ion temperature can be derived. An ultrafast-quenched plastic scintillation detector was used to measure the time of flight for the neutron at a low-imploded DT neutron yield (5×107 ~ 1 × l08) in the experiment performed on the Shenguang II laser facility. The typical temperatures of ablating targets for indirect drive were around 2.8 keV and the uncertainties were ± 30 % ~± 40%. The detection efficiency of the detector for DT neutrons was calibrated at a K-400 accelerator. The time response function of the detection system was calibrated by imploded neutrons from a DT-filled capsule, which can be regarded as a δ function pulsed neutron source due to its much narrower pulse width than that of the measured neutron time-of-flight spectrum.

  14. Annealing effects on the microwave linewidth broadening of FeCuNbSiB ferromagnetic films

    International Nuclear Information System (INIS)

    We systematically investigate the annealing effects on the microwave linewidth broadening of FeCuNbSiB ferromagnetic films with thickness of 100 nm. We correlate the non-uniform residual stress obtained from grazing incidence x-ray diffraction measurements with the ferromagnetic resonance (FMR) linewidth due to effective field inhomogeneities measured from broadband ferromagnetic resonance absorption measurements. We also estimate the annealing temperature effect on the Gilbert and two-magnon scattering contributions to the total ferromagnetic resonance FMR linewidth. We show that the effective field inhomogeneities constitute the main contribution to the microwave linewidth, while this contribution is related to the non-uniform residual stress in the films which is reduced by thermal annealing

  15. Broadening of mesophase temperature range induced by doping calamitic mesogen with banana-shaped mesogen

    Science.gov (United States)

    Cvetinov, Miroslav; Stojanović, Maja; Obadović, Dušanka; Vajda, Aniko; Fodor-Csorba, Katalin; Eber, Nandor

    2016-03-01

    We have investigated three binary mixtures composed of selected banana-shaped dopant in low concentrations and calamitic mesogen in high. Banana-shaped dopant forms a B7 phase, while the calamitic mesogen exhibit nematic and smectic SmA and SmC phases. The occurring mesophases have been identified by their optical textures. At dopant concentrations of 2.2 and 3.1 mol%, there is evident broadening of nematic and smectic SmA temperature ranges in respect to the pure calamitic compound. Yet, the mixture with dopant concentration of 7 mol% exhibits narrower temperature ranges of mesophases. Increasing dopant concentration caused lowering of all phase transitions temperatures (TI-N, TN-SmA, TSmA-SmC) in all investigated mixtures. Therefore, mixing classic calamitic compounds with novel banana-shaped compound in low concentrations is viable way to attain useful mesophase range for application in industry.

  16. Effect of spontaneously generated coherence on inversionless lasing gain in an atomic system with Doppler broadening

    Institute of Scientific and Technical Information of China (English)

    Ma Hui; Tan Xia; Tian Shu-Fen; Tong Dian-Min; Fan Xi-Jun

    2007-01-01

    We have studied the effect of the spontaneously generated coherence (SGC) on gain of lasing without inversion (LWI) in a closed three-level A-type atomic system with Doppler broadening. It is shown that, regardless of the driving and probe fields being co- or counter-propagating, at a suitable value of the Doppler width, we can obtain a much larger LWI gain with SGC than that without SGC; and the region of the LWI gain spectrum with SGC is obviously larger than that without SGC. When the Doppler width takes a constant value, the gain does not monotonically decrease or increase with increasing strength of SGC, the largest LWI gain can be obtained by adjusting strength of SGC. Generally speaking, the co-propagating probe and driving fields is favourable to obtain a larger LWI gain.

  17. Annealing effects on the microwave linewidth broadening of FeCuNbSiB ferromagnetic films

    Energy Technology Data Exchange (ETDEWEB)

    Alves, M. J. P.; Gonzalez-Chavez, D. E.; Sommer, R. L. [Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud 150, Urca, 22290-180 Rio de Janeiro, RJ (Brazil); Bohn, F. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, 59078-900 Natal, RN (Brazil)

    2015-03-28

    We systematically investigate the annealing effects on the microwave linewidth broadening of FeCuNbSiB ferromagnetic films with thickness of 100 nm. We correlate the non-uniform residual stress obtained from grazing incidence x-ray diffraction measurements with the ferromagnetic resonance (FMR) linewidth due to effective field inhomogeneities measured from broadband ferromagnetic resonance absorption measurements. We also estimate the annealing temperature effect on the Gilbert and two-magnon scattering contributions to the total ferromagnetic resonance FMR linewidth. We show that the effective field inhomogeneities constitute the main contribution to the microwave linewidth, while this contribution is related to the non-uniform residual stress in the films which is reduced by thermal annealing.

  18. Six-wave mixing spectroscopy in a Doppler-broadened cascade four-level system

    Energy Technology Data Exchange (ETDEWEB)

    Niu Jinyan; Wang Ruquan; Wang Bingbing; Wu Lingan; Fu Panming, E-mail: pmfu@aphy.iphy.ac.c [Laboratory of Optical Physics, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2009-09-14

    We study six-wave mixing (SWM) spectroscopy based on electromagnetically induced transparency in a Doppler-broadened cascade four-level system. It is found that the SWM spectra are extremely sensitive to the configuration of the incident beams, where the linewidth can be either Doppler-free or very broad, due to the polarization interference of atoms of different velocities. This polarization interference can be controlled in the presence of a strong coupling field. Moreover, SWM can be employed as a new type of Doppler-free Autler-Townes (AT) spectroscopy, which has better spectral resolution than conventional AT spectroscopy. Finally, we also reveal the intrinsic connection between frequency-domain SWM spectroscopy and time-domain photon echoes through studying the time-domain correspondence of SWM.

  19. Effects of Doppler broadening on Autler-Townes splitting in six-wave mixing

    Energy Technology Data Exchange (ETDEWEB)

    Niu Jinyan [Laboratory of Optical Physics, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); School of Mathematics, Physics and Biological Engineering, Inner Mongolia University of Science and Technology, Baotou 014010 (China); Pei Liya; Lu Xiaogang; Wang Ruquan; Wu Lingan; Fu Panming [Laboratory of Optical Physics, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2011-09-15

    The effects of Doppler broadening on Autler-Townes (AT) splitting in six-wave mixing (SWM) are investigated by the dressed-state model. We analyze the velocities at which the atoms are in resonance with the dressed states through Doppler frequency shifting and find that, depending on the wave-number ratio, there may be two resonant velocities which can originate from resonance with one of the dressed states or from resonance with two different dressed states. Based on this model, we discuss a novel type of AT doublet in the SWM spectrum, where macroscopic effects play an important role. Specifically, the existence of resonant peaks requires polarization interference between atoms of different velocities in addition to a change in the number of resonant atoms involved. Our model can also be employed to analyze electromagnetically induced transparency resonance and other types of Doppler-free high-resolution AT spectroscopy.

  20. The imperative to prevent diabetes complications: a broadening spectrum and an increasing burden despite improved outcomes.

    Science.gov (United States)

    Twigg, Stephen M; Wong, Jencia

    2015-04-01

    Diabetes mellitus and its complications are common; the complications are, of themselves, a major reason to manage diabetes. Recent data from Australia and similar developed health care systems overseas indicate that morbidity and mortality outcomes relating to diabetes complications are improving. However, these benefits are offset by increasing numbers of people diagnosed with diabetes, resulting in an increased disease burden with significant health care implications. Thus the imperative to prevent diabetes and diabetes complications has never been greater. Furthermore, the recognised spectrum of diabetes complications is broadening, especially complications relating to lipid levels, insulin resistance and the metabolic syndrome. Clinicians now need to be aware of both traditional complications (eg, nephropathy and cardiovascular disease) and non-traditional complications (eg, polycystic ovary syndrome, non-alcoholic fatty liver disease, some cancers and eating disorders). Complications outcomes could be further improved by decreasing the evidence-treatment gap - for example, by increasing personalisation of care in managing diabetes complications.

  1. Spectral anti-broadening due to four-wave mixing in optical fibers

    CERN Document Server

    Balk, Alexander M

    2015-01-01

    We show that the four-wave mixing can restrict spectral broadening. This is a general physical phenomenon that occurs in one-dimensional systems of four wave packets that resonantly interact "2-to-2": $ \\omega_1+\\omega_2=\\omega_3+\\omega_4,\\; k_1+k_2=k_3+k_4$, when an annihilation of one pair of waves results in the creation of another pair. In addition, for this phenomenon to occur, the group velocities $C_1,C_2,C_3,C_4$ of the packets should be in a certain order: The extreme value (max or min) of the four group velocities should be in the same pair with the middle value of the remaining three, e.g. $C_1

  2. Nitride superluminescent diodes with broadened emission spectrum fabricated using laterally patterned substrate.

    Science.gov (United States)

    Kafar, A; Stanczyk, S; Sarzynski, M; Grzanka, S; Goss, J; Targowski, G; Nowakowska-Siwinska, A; Suski, T; Perlin, P

    2016-05-01

    We demonstrate InGaN/GaN superluminescent diodes with broadened emission spectra fabricated on surface-shaped bulk GaN (0001) substrates. The patterning changes the local vicinal angle linearly along the device waveguide, which results in an indium incorporation profile in InGaN quantum wells. The structure was investigated by microphotoluminescence mapping, showing a shift of central emission wavelength from 413 nm to 430 nm. Spectral full width at half maximum of processed superluminescent diodes is equal to 6.1 nm, while the reference chips show 3.4 nm. This approach may open the path for using nitride devices in applications requiring broad emission spectrum and high beam quality, such as optical coherence tomography.

  3. Cross Functional Career Navigation: The Way to Broaden Your Career Options

    Science.gov (United States)

    Greenhalgh, Todd

    2000-03-01

    In today's rapid paced global environment, broadening career options for career development depends on successful cross-functional career navigation. For scientists and engineers, this means developing a diversity of skills in addition to a strong technical foundation. Fortunately, companies use cross-functional teams as one of the key tools for rapidly developing and commercializing products and services. Participation on these teams carries with it the additional benefit of allowing an individual to develop new skills, and to gain valuable expertise in areas that are critical to the growth of their company, their industry and, most importantly, their career. This talk will outline some of the important cross functional skills that can propel your career ahead and ways in which you can take charge of your career mapping and enhance your value and employability.

  4. Amplifying modeling for broad bandwidth pulse in Nd:glass based on hybrid-broaden mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Sujingqin; Lanqin, L; Wenyi, W; Feng, J; Xiaofeng, W; Xiaomin, Z [Research Center of Laser Fusion, China Academy of Engineering Physics, P. O. Box 919-988, Mianyang, China, 621900 (China); Bin, L [School of Computer and Communication Engineering, Southwest Jiaotong University, Chengdu. China, 610031 (China)], E-mail: sujingqin@tom.com

    2008-05-15

    In this paper, the cross relaxation time is proposed to combine the homogeneous and inhomogeneous broaden mechanism for broad bandwidth pulse amplification model. The corresponding velocity equation, which can describe the response of inverse population on upper and low energy level of gain media to different frequency of pulse, is also put forward. The gain saturation and energy relaxation effect are also included in the velocity equation. Code named CPAP has been developed to simulate the amplifying process of broad bandwidth pulse in multi-pass laser system. The amplifying capability of multi-pass laser system is evaluated and gain narrowing and temporal shape distortion are also investigated when bandwidth of pulse and cross relaxation time of gain media are different. Results can benefit the design of high-energy PW laser system in LFRC, CAEP.

  5. Suppression of space broadening of exciton polariton beams by Bloch oscillation effects

    CERN Document Server

    Duan, Xudong; Zhang, Yongyou

    2015-01-01

    We theoretically study the transport of exciton polaritons under different applied photon potentials. The relation between the photon potentials and the thickness of the cavity layer is calculated by the finite element simulation. The theoretical analysis and numerical calculation indicate that the cavity photon potential is proportional to the thickness of the cavity layer with the coefficient being about $1.8$ meV/nm. Further, the periodic and linear photon potentials are considered to control the transport of the exciton polaritons in weak- and strong-field pump situations. In both situations the periodic potential cannot by itself effectively suppress the scatterings of the disorder potentials of the cavity photons and excitons and the nonlinear exciton-exciton interaction. When the linear potential is added to the cavity photons, the polariton transport exhibits the Bloch oscillation behavior. Importantly, the polariton Bloch oscillation can strongly suppress the space broadening due to the disorder pote...

  6. Inhomogeneous broadening of optical transitions of 87Rb atoms in an optical nanofiber trap

    CERN Document Server

    Lee, J; Hoffman, J E; Orozco, L A; Rolston, S L

    2014-01-01

    We experimentally demonstrate optical trapping of 87Rb atoms using a two-color evanescent field around an optical nanofiber. In our trapping geometry, a blue-detuned traveling wave whose polarization is nearly parallel to the polarization of a red-detuned standing wave produce significant vector light shifts that lead to broadening of the absorption profile of a near-resonant beam at the trapping site. A model that includes scalar, vector, and tensor light shifts of the probe transition $5S_{1/2}$-$5P_{3/2}$ from the trapping beams; weighted by the temperature-dependent position of the atoms in the trap qualitatively describe the observed asymmetric profile, and explained differences with previous experiments that used Cs atoms. The model provides a consistent way to extract the number of atoms in the trap.

  7. Legal intervention in civil commitment: the impact of broadened commitment criteria.

    Science.gov (United States)

    Durham, M L; Pierce, G L

    1986-03-01

    Recent legal changes in Washington State have broadened the grave-disability criterion for civil commitment of the mentally ill. Analysis of data from state mental hospitals and from records of commitment authorities in Washington's two largest counties revealed that, while there was an increase in the number of involuntary hospitalizations immediately before and after the changes in law, there was a virtual disappearance of voluntary patients in state hospitals. Moreover, expansion of the definition of "grave disability" resulted in a move toward a parens patriae-dominated civil commitment system. Analysis of the empirical consequences of the legal changes on commitment decisions is presented, along with the response of mental health officials and the public.

  8. Radiative pT-broadening of high energy quarks and gluons in QCD matter

    CERN Document Server

    Liou, Tseh; Wu, Bin

    2013-01-01

    We study radiative $p_{\\perp}$-broadening of high energy quarks passing through hot and cold QCD matter. With $L$ the length of the matter and $l_{0}$ the size of constituents of the matter we find $\\avg{p_{\\perp}^{2}}$ has both double logarithmic terms, $\\ln^{2}(L/l_{0})$, and single logarithmic terms, $\\ln(L/l_{0})$, coming from gluon radiation induced by the matter. We use a (slight) extension of a formalism developed by B. Zakharov for studying energy loss, a formalism which, for much of our calculation, reduces to a simple dipole scattering analysis. We estimate the radiative contribution to be a sizable correction to the nonradiative value of $\\avg{p_{\\perp}^{2}}$. We also carry out a resummation of the double logarithmic terms that we find, and we briefly discuss running coupling effects which appear here in a rather unusual way.

  9. Coincidence Doppler broadening study of Eurofer 97 irradiated in spallation environment

    Energy Technology Data Exchange (ETDEWEB)

    Sabelová, V., E-mail: veronika.sabelova@stuba.sk [Institute of Nuclear and Physical Engineering, Faculty of Electrical Engineering and Information Technology, Slovak University of Technology in Bratislava, Ilkovičova 3, 81219 Bratislava (Slovakia); Laboratory for Nuclear Materials, Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Kršjak, V. [Laboratory for Nuclear Materials, Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Kuriplach, J. [Department of Low Temperature Physics, Faculty of Mathematics and Physics, Charles University in Prague, V Holešovičkách 2, 18000 Prague 8 (Czech Republic); Dai, Y. [Laboratory for Nuclear Materials, Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Slugeň, V. [Institute of Nuclear and Physical Engineering, Faculty of Electrical Engineering and Information Technology, Slovak University of Technology in Bratislava, Ilkovičova 3, 81219 Bratislava (Slovakia)

    2015-03-15

    The behavior of transmutation helium during isochronal annealing of irradiated Eurofer 97 was investigated using coincidence Doppler broadening spectroscopy (CDBS). The investigated ferritic martensitic steel was irradiated in 2000 and 2001 in the frame of the STIP-II project at the Swiss neutron spallation source (SINQ) (irradiation with neutrons and protons) at the Paul Scherrer Institute (PSI). During isochronal annealing experiment, coarsening of vacancy clusters and/or growth of helium bubbles was observed at T ⩾ 500 °C. This process causes an increase of low-momentum annihilation events and related increase of the S parameter during thermal treatment of material. On the other hand, the maximum concentration of helium in small vacancy clusters (V{sub n}) was observed after annealing at 400 °C, where an excellent correlation with the calculated CDBS profiles of V{sub n} + He{sub m} clusters was found.

  10. Coincidence Doppler broadening study of Eurofer 97 irradiated in spallation environment

    Science.gov (United States)

    Sabelová, V.; Kršjak, V.; Kuriplach, J.; Dai, Y.; Slugeň, V.

    2015-03-01

    The behavior of transmutation helium during isochronal annealing of irradiated Eurofer 97 was investigated using coincidence Doppler broadening spectroscopy (CDBS). The investigated ferritic martensitic steel was irradiated in 2000 and 2001 in the frame of the STIP-II project at the Swiss neutron spallation source (SINQ) (irradiation with neutrons and protons) at the Paul Scherrer Institute (PSI). During isochronal annealing experiment, coarsening of vacancy clusters and/or growth of helium bubbles was observed at T ⩾ 500 °C. This process causes an increase of low-momentum annihilation events and related increase of the S parameter during thermal treatment of material. On the other hand, the maximum concentration of helium in small vacancy clusters (Vn) was observed after annealing at 400 °C, where an excellent correlation with the calculated CDBS profiles of Vn + Hem clusters was found.

  11. Processing of doppler broadening spectra of positron annihilation radiation and its application

    International Nuclear Information System (INIS)

    An unfolding method to obtain intrinsic distributions of positron annihilation radiation from Doppler broadening spectra by means of an iterative method is described. The intrinsic distribution can be fitted into a Gaussian function and an invert parabola function. Electron momentum distribution and Fermi energy can be calculated. Positron annihilation spectra for 13 materials were analyzed. Their momentum distribution and Fermi energy were obtained. The results show that electron momentum distributions for various materials are different and experimental values of Fermi energy for various materials are consistent with theoretical ones. The study on amorphous and crystalline Fe-Si-B alloys indicates that momentum distributions are almost the same, while there is a small difference on Fermi energy

  12. Interaction of runaway electrons with lower hybrid waves via anomalous Doppler broadening

    Science.gov (United States)

    Martín-Solís, J. R.; Sánchez, R.; Esposito, B.

    2002-05-01

    Due to the relativistic decrease of the electron cyclotron frequency, a cyclotron resonance may appear between runaway electrons and lower hybrid waves. A single particle description of the runaway dynamics [J. R. Martín-Solís et al., Phys. Plasmas 5, 2370 (1998)] is extended to analyze the effect of the interaction of runaway electrons with lower hybrid waves via anomalous Doppler broadening. The conditions under which the resonant interaction can play a role in limiting the runaway energy are established and it is shown that, under typical lower hybrid current drive operation parameters, an efficient wave-particle coupling may occur. Observations of a fast pitch angle scattering event during the current decay phase of Ohmic discharges in the Toroidal Experiment for Technically Oriented Research (TEXTOR) [R. J. E. Jaspers, Ph.D. thesis, Technical University Eindhoven (1995)] are interpreted in terms of such interaction.

  13. production lines

    Directory of Open Access Journals (Sweden)

    Jingshan Li

    2000-01-01

    Full Text Available In this work, serial production lines with finished goods buffers operating in the pull regime are considered. The machines are assumed to obey Bernoulli reliability model. The problem of satisfying customers demand is addressed. The level of demand satisfaction is quantified by the due-time performance (DTP, which is defined as the probability to ship to the customer a required number of parts during a fixed time interval. Within this scenario, the definitions of DTP bottlenecks are introduced and a method for their identification is developed.

  14. Asymmetric Speed-Dependent Spectral Line Shapes in Cadmium-Foreign-Gas Systems

    International Nuclear Information System (INIS)

    Results of a series of experiments on collisional and speed-dependent effects caused by various foreign gases on the 326.1 nm Cd intercombination line are discussed in detail. Using a laser-induced fluorescence method precise measurements of pressure-broadened profiles of this line perturbed by all rare gases and some molecular gases (H2 , D2 , N2 and CH4 ) were performed in our lab oratory at pressures up to 400 Torr. The line shapes were analyzed in terms of a Speed-Dependent Asymmetric Voigt Profile (SDAVP) and the role of the correlation between pressure broadening rate and emitter velocity as well as of the finite duration of collisions were thoroughly investigated. These effects were found to be particularly important in the cases of perturbation by heavy , i.e. high-polarizability rare-gas atoms (Ar, Kr, Xe). Pressure-broadening and shift rates and the collision-time asymmetry factors as well as effective cross sections for the broadening and shifting of the 326.1 nm Cd line were determined and compared with those calculated on the basis of the van der Waals, Morse and Czuchaj-Stoll potentials. (author)

  15. [Participatory potential and deliberative function: a debate on broadening the scope of democracy through the health councils].

    Science.gov (United States)

    Bispo Júnior, José Patrício; Gerschman, Sílvia

    2013-01-01

    This article reflects upon the relation between democracy and health councils. It seeks to analyze the councils as a space for broadening the scope of democracy. First, some characteristics and principles of the liberal democratic regime are presented, with an emphasis on the minimalist and procedural approach of decision-making. The fragilities of the representative model and the establishment of new relations between the Government and society are then discussed in light of the new social grammar and the complexity of the division between governmental and societal responsibilities. The principles of deliberative democracy and the idea of substantive democracy are subsequently presented. Broadening the scope of democracy is understood not only as the guarantee of civil and political rights, but also especially, of social rights. Lastly, based on discussion of the participation and deliberation categories, the health councils are analyzed as potential mechanisms for broadening the scope of democracy.

  16. Spectral broadening and temporal compression of ∼ 100 fs pulses in air-filled hollow core capillary fibers.

    Science.gov (United States)

    Li, C; Rishad, K P M; Horak, P; Matsuura, Y; Faccio, D

    2014-01-13

    We experimentally study the spectral broadening of intense, ∼ 100 femtosecond laser pulses at 785 nm coupled into different kinds of hollow core capillary fibers, all filled with air at ambient pressure. Differently from observations in other gases, the spectra are broadened with a strong red-shift due to highly efficient intrapulse Raman scattering. Numerical simulations show that such spectra can be explained only by increasing the Raman fraction of the third order nonlinearity close to 100%. Experimentally, these broadened and red-shifted pulses do not generally allow for straightforward compression using, for example, standard chirped mirrors. However, using special hollow fibers that are internally coated with silver and polymer we obtain pulse durations in the sub-20 fs regime with energies up to 300 μJ. PMID:24515074

  17. Ac Stark splitting in multiphoton excitation of atomic hydrogen in flames: Abnormal peak asymmetry due to pressure broadening

    International Nuclear Information System (INIS)

    A theory of ac Stark (or Autler-Townes) splitting occurring in double optical resonances, one of which is a two-photon transition is developed. Both laser bandwidth and collisional broadening effects are included. Theoretical results are in excellent agreement with Goldsmith's observation of two-peaked structures in the multiphoton excitation spectra of atomic hydrogen in atmospheric-pressure flames. This is believed to be the first study demonstrating that the peak asymmetry in an ac Stark doublet can be reversed due to pressure broadening

  18. A broadened classical master equation approach for nonadiabatic dynamics at metal surfaces: Beyond the weak molecule-metal coupling limit.

    Science.gov (United States)

    Dou, Wenjie; Subotnik, Joseph E

    2016-01-14

    A broadened classical master equation (BCME) is proposed for modeling nonadiabatic dynamics for molecules near metal surfaces over a wide range of parameter values and with arbitrary initial conditions. Compared with a standard classical master equation-which is valid in the limit of weak molecule-metal couplings-this BCME should be valid for both weak and strong molecule-metal couplings. (The BCME can be mapped to a Fokker-Planck equation that captures level broadening correctly.) Finally, our BCME can be solved with a simple surface hopping algorithm; numerical tests of equilibrium and dynamical observables look very promising. PMID:26772563

  19. Line-of-sight geometrical and instrumental resolution effects on intensity perturbations by sausage modes

    CERN Document Server

    Antolin, Patrick

    2013-01-01

    Diagnostics of MHD waves in the solar atmosphere is a topic which often encounters problems of interpretation, due partly to the high complexity of the solar atmospheric medium. Forward modeling can significantly guide interpretation, bridging the gap between numerical simulations and observations, and increasing the reliability of mode identification for application of MHD seismology. In this work we aim at determining the characteristics of the fast MHD sausage mode in the corona on the modulation of observable quantities such as line intensity and spectral line broadening. Effects of line-of-sight angle, and spatial, temporal and spectral resolutions are considered. We take a cylindrical tube simulating a loop in a low-{\\beta} coronal environment with an optically thin background, and let it oscillate with the fast sausage mode. A parametric study is performed. Among other results, we show that regardless of the ionisation state of the plasma, the variation of spectral line broadening can be significant, e...

  20. Experimental measurements of selenium x-ray laser spectral line profiles

    Energy Technology Data Exchange (ETDEWEB)

    Koch, J.A.; MacGowan, B.J.; Da Silva, L.B.; Matthews, D.L.; London, R.A.; Lee, R.W.; Mrowka, S. [Lawrence Livermore National Lab., CA (US); Underwood, J.H.; Batson, P.J. [Lawrence Berkeley Lab., CA (US)

    1993-03-01

    The authors discuss their recent measurements of the spectral width of the 206.38 {Angstrom} x-ray laser transition in Ne-like Se. These measurements used a high-resolution grating spectrometer and were performed over a wide range of laser amplifier lengths. The data have enabled them to extrapolate the intrinsic line width and to observe the effects of gain-narrowing and saturation on the line profile. They find an intrinsic width which is 1.4 times the Doppler width, they observe gain-narrowing in intermediate length amplifiers, and they observe no re-broadening in long, saturated amplifiers. These results suggest that collisional line-broadening has a significant effect on the line profile and saturation behavior of this laser.

  1. Transition probabilities and Stark-broadening parameters of neutral and singly ionized lead

    Science.gov (United States)

    Miller, M. H.; Bengston, R. D.; Lindsay, J. M.

    1979-01-01

    Strengths and Stark widths of the prominent visible PbI and PbII lines are measured in emission by means of a gas-driven shock tube. Absolute ionic line strengths for 7s-7p and 7p-7d arrays conform well to quantum-mechanical sum rules and agree with theoretical predictions, but 6d-5f results differ markedly from central-field approximations. Neutral-line strengths agree satisfactorily with available comparison data. Semiempirical theory predicts the widths of PbII lines with characteristic reliability of better than 25%.

  2. Unresolved dielectronic satellites of the resonance line of heliumlike iron (Fe XXV)

    International Nuclear Information System (INIS)

    (1s2nl - 1s2pnl, n greater than or equal to 3) dielectronic satellites of the resonance line of Fe XXV at 1.85 A have been observed from PLT (Princeton Large Torus) tokamak discharges and are used for a detailed comparison with theory. The necessary corrections for Doppler broadening measurements are discussed, and accurate satellite to resonance line ratios allowing for a determination of the total dielectronic recombination rate of Fe XXV are derived

  3. Absorption coefficient, transition probability, and collision-broadening frequency of dimethylether at He-Xe laser 3.51-micron wavelength

    Science.gov (United States)

    Siegman, A. E.; Wang, S. C.

    1970-01-01

    Absorptivity, transition probability and collision broadening frequency of dimethylether at 3.51 micron He-Xe laser wavelength, noting pressure dependence, transition lifetime and saturation intensity

  4. Direct Measurements of Line-Mixing Coefficients in the nu1 + nu2 Q Branch of CO2

    Science.gov (United States)

    Berman; Duggan; Sinclair; May; Drummond

    1997-04-01

    High-resolution measurements of the (nu1 + nu2) Q branch of pure CO2 were made using a difference frequency spectrometer with resolution of 5 x 10(-5) cm-1 and a signal-to-noise ratio of 2000:1. Lines Q(2) through Q(32) were measured with up to 14 lines in a single spectrum. The analysis of the branch has been performed on data taken at 301 K and pressures less than 11 kPa. The spectra were analyzed on a line-by-line basis within the Rosenkranz approximation of weak overlap [P. W. Rosenkranz, IEEE Trans. Antennas Propagation AP-23, 498 (1975)]. The lineshape profile included Doppler broadening and Dicke narrowing [R. H. Dicke, Phys. Rev. 89, 472 (1953)] using a modified hard collision model [S. G. Rautian and I. I. Sobel'man, Sov. Phys. Uspekh. 9, 701 (1967)] with line mixing. For each line the broadening, Dicke narrowing, and line-mixing coefficients were determined. The broadening coefficients are in good agreement with measurements of lines belonging to different CO2 bands. Our measured line-mixing parameters are compared to those predicted by a relaxation matrix which was calculated from an exponential power gap (EPG) law [L. L. Strow, D. C. Tobin, and S. E. Hannon, J. Quant. Spectrosc. Radiat. Transfer 52, 281 (1994)]. The vibrational band intensity and the linear pressure shift of the branch were also measured. Copyright 1997Academic Press

  5. Broadening the Participation of Native American/span>s in Earth Science

    Science.gov (United States)

    Bueno Watts, Nievita

    Climate change is not a thing of the future. Indigenous people are being affected by climate changes now. Native American Earth scientists could help Native communities deal with both climate change and environmental pollution issues, but are noticeably lacking in Earth Science degree programs. The Earth Sciences produce the lowest percentage of minority scientists when compared with other science and engineering fields. Twenty semi-structured interviews were gathered from American Indian/ Alaska Native Earth Scientists and program directors who work directly with Native students to broaden participation in the field. Data was analyzed using qualitative methods and constant comparison analysis. Barriers Native students faced in this field are discussed, as well as supports which go the furthest in assisting achievement of higher education goals. Program directors give insight into building pathways and programs to encourage Native student participation and success in Earth Science degree programs. Factors which impede obtaining a college degree include financial barriers, pressures from familial obligations, and health issues. Factors which impede the decision to study Earth Science include unfamiliarity with geoscience as a field of study and career choice, the uninviting nature of Earth Science as a profession, and curriculum that is irrelevant to the practical needs of Native communities or courses which are inaccessible geographically. Factors which impede progress that are embedded in Earth Science programs include educational preparation, academic information and counseling and the prevalence of a Western scientific perspective to the exclusion of all other perspectives. Intradepartmental relationships also pose barriers to the success of some students, particularly those who are non-traditional students (53%) or women (80%). Factors which support degree completion include financial assistance, mentors and mentoring, and research experiences. Earth scientists

  6. Broadening and Amplification of an Infrared Femtosecond Pulse for Optical Parametric Chirped-Pulse Amplification

    Institute of Scientific and Technical Information of China (English)

    WANG He-Lin; YANG Ai-Jun; LENG Yu-Xin

    2011-01-01

    A high-average-power diode-pumped narrowband regenerative chirped pulse amplifier is developed using the thin-rod Nd:YAG laser architecture for optical parametric chirped-pulse amplification (OPCPA).The effect of the etalons on the amplified pulse in the regenerative cavity is studied experimentally and theoretically.By inserting glass etalons of thickness 1 mm and 5 mm into the regenerative cavity,the pre-stretching pulse from an (O)ffner stretcher is further broadened to above 200ps,which matches the amplification windows of the signal pulses in OPCPA and is suitable for use as a pump source in the OPCPA system.The bandwidth of the amplified pulse is 1.5 nm,and an output energy of 2mJ is achieved at a repetition rate of 10 Hz.Optical parametric chirped pulse amplification (OPCPA)[1-4] has attracted a great deal of attention as the most promising technique for generating ultrashort ultrahigh-peak-power laser pulses because of its very broad gain bandwidth,negligible thermal load on the nonlinear crystal,and extremely high singlepass gain as compared to amplifiers based on laser gain media.For efficient amplification and high fidelity of dispersion compensation in OPCPA,a femtosecond seed pulse is first stretched to several tens of picoseconds with a bulk grating stretcher or a fiber stretcher.%A high-average-power diode-pumped narrowband regenerative chirped pulse amplifier is developed using the thin-rod Nd:YAG laser architecture for optical parametric chirped-pulse amplification (OPCPA). The effect of the etalons on the amplified pulse in the regenerative cavity is studied experimentally and theoretically. By inserting glass etalons of thickness 1 mm and 5 mm into the regenerative cavity, the pre-stretching pulse from an (O)finer stretcher is further broadened to above 200 ps, which matches the amplification windows of the signal pulses in OPCPA and is suitable for use as a pump source in the OPCPA system. The bandwidth of the amplified pulse is 1.5 nm, and an

  7. Peak broadening in paper chromatography and related techniques : IV. The mechanism of the mass transfer term in paper chromatography

    NARCIS (Netherlands)

    Ligny, C.L. de; Remijnse, A.G.

    1968-01-01

    The mechanism of peak broadening in paper chromatography is investigated by comparing the peak widths obtained in chromatography with those caused only by diffusion, for a set of amino acids of widely differing RF values and with eight kinds of Whatman paper. The results show that longitudinal diff

  8. Mortality Salience and Positive Affect Influence Adolescents' Attitudes toward Peers with Physical Disabilities: Terror Management and Broaden and Build Theories

    Science.gov (United States)

    Taubman-Ben-Ari, Orit; Eherenfreund-Hager, Ahinoam; Findler, Liora

    2011-01-01

    Attitudes toward teenagers with and without physical disabilities, and their social acceptance, were examined from the perspective of terror management theory and the broaden and build theory. Participants (n = 390, aged 13-17) were divided into 3 experimental conditions: positive emotions, mortality salience, and control. Then, they were shown…

  9. If You Build Teachers, Will Students Come? The Role of Teachers in Broadening Computer Science Learning for Urban Youth

    Science.gov (United States)

    Goode, Joanna

    2007-01-01

    Despite the digital saturation of today's youth across demographic groups, students of color and females remain severely underrepresented in computer science. Reporting on a sequential mixed methods study, this article explores the ways that high school computer science teachers can act as change agents to broaden the participation in computing…

  10. Local Talent: By Tapping into the Resources Just outside Their School Walls, Music Teachers Can Help Broaden Their Students' Horizons

    Science.gov (United States)

    Randall, Mac

    2009-01-01

    Many music teachers across the country have learned how beneficial it can be to tap into the communities around them. The author discusses how music teachers can help broaden their students' horizons by tapping into the resources just outside their school walls. One way is by employing local talents. Another is to put an ad in nearby music stores,…

  11. Progress in the measurement of temperature-dependent N2–N2 collision-induced absorption and H2-broadening of cold and hot CH4

    Science.gov (United States)

    Sung, Keeyoon; Wishnow, Ed; Venkataraman, Malathy; Brown, Linda R.; Ozier, Irving; Benner, D. Chris; Crawford, Tomithy J.; Mantz, Arlan; Smith, Mary-Ann H.

    2016-10-01

    We report preliminary measurements from two separate laboratory studies: (A) collision-induced absorption (CIA) of nitrogen in the far-infrared at temperatures between 78 and 130 K; and (B) temperature dependence of H2-broadening of CH4 in the near infrared at temperatures between 100 and 370 K.(A) Nitrogen collision-induced absorption provides the primary opacity of Titan at long wavelengths, thereby playing a critical role in determining the heat balance as well as the atmospheric composition and dynamics. Our new measurements of the nitrogen absorption spectrum at temperatures from 78 to 130 K are consistently ~20% higher than predictions made using theoretical models of Borysow and Frommhold (1986) [ApJ, 311, 1043] and of Karman et al. (2015)[J Chem Phys, 142, 084306]. However, the new data are consistent with the previous measurements at 78 K by the UBC group (Wishnow et al. 1996)[J Chem Phys, 104, 3511]. We present preliminary results for the N2-N2 CIA coefficients and their temperature dependence between 78 and 130 K, and comparisons with the above theoretical calculations.(B) In support of the Jovian and exoplanet atmospheric remote sensing in the near infrared, we have measured the temperature dependence of H2-broadened half width and pressure shift coefficients of CH4, both of which are known to be rotational quantum number dependent. We studied both cold and hot CH4 in the K band (~2.2 μm) with the focus on a) weaker lines in the v2+v3 band at low temperatures for cold giant planets and b) stronger lines in the v3+v4 band at elevated temperatures for extra-solar planets (e.g., hot-Jupiters). Three custom-built gas absorption cells (two cold and one hot) were used to obtain the spectra of CH4 and H2 mixtures at temperatures between 100 and 370 K. We will discuss our on-going spectrum analysis for a few select J manifolds and provide comparisons with published values, which are available only at room temperature.

  12. Fabrication of a 2-DOF electromagnetic energy harvester with in-phase vibrational bandwidth broadening

    Science.gov (United States)

    Chen, Shih-Jui; Wu, Jia-Yin

    2016-09-01

    A vibration structure with two-degrees-of-freedom is proposed to increase the usable bandwidth of a micromachined electromagnetic energy harvester. Compared with the structure of a pure cantilever harvester, the proposed structure is formed by integrating a spiral diaphragm into a U-shaped cantilever diaphragm. By performing finite element analysis, the resonance frequencies of the two diaphragms are designed with a slight shift, both lower than 300 Hz. In addition, to achieve output bandwidth broadening, electroplated copper coils on the spiral and the U-shaped cantilever are coupled and the connection sequences of the coupled coils are arranged such that single- or duo-mode tuning of the energy harvester can be realized. The harvester delivers powers of 22.1 and 21.5 nW at two resonance frequencies of 211 and 274 Hz, respectively, in the duo-mode operation. The proposed spiral-cantilever coupled energy harvester has lower resonance frequencies and broader bandwidth than a pure cantilever-type harvester of equal area, and can therefore harvest more energy from the environment.

  13. Broadening Participation in the Life Sciences with Social–Psychological Interventions

    Science.gov (United States)

    Tibbetts, Yoi; Harackiewicz, Judith M.; Priniski, Stacy J.; Canning, Elizabeth A.

    2016-01-01

    Randomized controlled trials (RCTs) have recently documented the positive effects of social–psychological interventions on the performance and retention of underrepresented students in the life sciences. We review two types of social–psychological interventions that address either students’ well-being in college science courses or students’ engagement in science content. Interventions that have proven effective in RCTs in science courses (namely, utility-value [UV] and values-affirmation [VA] interventions) emphasize different types of student values—students’ perceptions of the value of curricular content and students’ personal values that shape their educational experiences. Both types of value can be leveraged to promote positive academic outcomes for underrepresented students. For example, recent work shows that brief writing interventions embedded in the curriculum can increase students’ perceptions of UV (the perceived importance or usefulness of a task for future goals) and dramatically improve the performance of first-generation (FG) underrepresented minority students in college biology. Other work has emphasized students’ personal values in brief essays written early in the semester. This VA intervention has been shown to close achievement gaps for women in physics classes and for FG students in college biology. By reviewing recent research, considering which interventions are most effective for different groups, and examining the causal mechanisms driving these positive effects, we hope to inform life sciences educators about the potential of social–psychological interventions for broadening participation in the life sciences. PMID:27543632

  14. Intrinsic homogeneous linewidth and broadening mechanisms of excitons in monolayer transition metal dichalcogenides

    KAUST Repository

    Moody, Galan

    2015-09-18

    The band-edge optical response of transition metal dichalcogenides, an emerging class of atomically thin semiconductors, is dominated by tightly bound excitons localized at the corners of the Brillouin zone (valley excitons). A fundamental yet unknown property of valley excitons in these materials is the intrinsic homogeneous linewidth, which reflects irreversible quantum dissipation arising from system (exciton) and bath (vacuum and other quasiparticles) interactions and determines the timescale during which excitons can be coherently manipulated. Here we use optical two-dimensional Fourier transform spectroscopy to measure the exciton homogeneous linewidth in monolayer tungsten diselenide (WSe2). The homogeneous linewidth is found to be nearly two orders of magnitude narrower than the inhomogeneous width at low temperatures. We evaluate quantitatively the role of exciton–exciton and exciton–phonon interactions and population relaxation as linewidth broadening mechanisms. The key insights reported here—strong many-body effects and intrinsically rapid radiative recombination—are expected to be ubiquitous in atomically thin semiconductors.

  15. The Geoscience Alliance--A National Network for Broadening Participation of Native Americans in the Geosciences

    Science.gov (United States)

    Dalbotten, D. M.; Berthelote, A. R.

    2014-12-01

    The Geoscience Alliance is a national alliance of individuals committed to broadening participation of Native Americans in the geosciences. Native Americans in this case include American Indians, Alaska Natives and people of Native Hawai'ian ancestry. Although they make up a large percentage of the resource managers in the country, they are underrepresented in degrees in the geosciences. The Geoscience Alliance (GA) members are faculty and staff from tribal colleges, universities, and research centers; native elders and community members; industry, agency, and corporate representatives; students (K12, undergraduate, and graduate); formal and informal educators; and other interested individuals. The goals of the Geoscience Alliance are to 1) create new collaborations in support of geoscience education for Native American students, 2) establish a new research agenda aimed at closing gaps in our knowledge on barriers and best practices related to Native American participation in the geosciences, 3) increase participation by Native Americans in setting the national research agenda on issues in the geosciences, and particularly those that impact Native lands, 4) provide a forum to communicate educational opportunities for Native American students in the geosciences, and 5) to understand and respect indigenous traditional knowledge. In this presentation, we look at the disparity between numbers of Native Americans involved in careers related to the geosciences and those who are receiving bachelors or graduate degrees in the geosciences. We address barriers towards degree completion in the geosciences, and look at innovative programs that are addressing those barriers.

  16. Positron annihilation Doppler broadening spectroscopy study on Fe-ion irradiated NHS steel

    Science.gov (United States)

    Zhu, Huiping; Wang, Zhiguang; Gao, Xing; Cui, Minghuan; Li, Bingsheng; Sun, Jianrong; Yao, Cunfeng; Wei, Kongfang; Shen, Tielong; Pang, Lilong; Zhu, Yabin; Li, Yuanfei; Wang, Ji; Song, Peng; Zhang, Peng; Cao, Xingzhong

    2015-02-01

    In order to study the evolution of irradiation-induced vacancy-type defects at different irradiation fluences and temperatures, a new type of ferritic/martensitic (F/M) steel named NHS (Novel High Silicon) was irradiated by 3.25 MeV Fe-ion at room temperature and 723 K to fluences of 4.3 × 1015 and 1.7 × 1016 ions/cm2. After irradiation, vacancy-type defects were investigated with variable-energy positron beam Doppler broadening spectra. Energetic Fe-ions produced a large number of vacancy-type defects in the NHS steel, but one single main type of vacancy-type defect was observed in both unirradiated and irradiated samples. The concentration of vacancy-type defects decreased with increasing temperature. With the increase of irradiation fluence, the concentration of vacancy-type defects increased in the sample irradiated at RT, whereas for the sample irradiated at 723 K, it decreased. The enhanced recombination between vacancies and excess interstitial Fe atoms from deeper layers, and high diffusion rate of self-interstitial atoms further improved by diffusion via grain boundary and dislocations at high temperature, are thought to be the main reasons for the reversed trend of vacancy-type defects between the samples irradiated at RT and 723 K.

  17. Broadening Participation in the Life Sciences with Social-Psychological Interventions.

    Science.gov (United States)

    Tibbetts, Yoi; Harackiewicz, Judith M; Priniski, Stacy J; Canning, Elizabeth A

    2016-01-01

    Randomized controlled trials (RCTs) have recently documented the positive effects of social-psychological interventions on the performance and retention of underrepresented students in the life sciences. We review two types of social-psychological interventions that address either students' well-being in college science courses or students' engagement in science content. Interventions that have proven effective in RCTs in science courses (namely, utility-value [UV] and values-affirmation [VA] interventions) emphasize different types of student values-students' perceptions of the value of curricular content and students' personal values that shape their educational experiences. Both types of value can be leveraged to promote positive academic outcomes for underrepresented students. For example, recent work shows that brief writing interventions embedded in the curriculum can increase students' perceptions of UV (the perceived importance or usefulness of a task for future goals) and dramatically improve the performance of first-generation (FG) underrepresented minority students in college biology. Other work has emphasized students' personal values in brief essays written early in the semester. This VA intervention has been shown to close achievement gaps for women in physics classes and for FG students in college biology. By reviewing recent research, considering which interventions are most effective for different groups, and examining the causal mechanisms driving these positive effects, we hope to inform life sciences educators about the potential of social-psychological interventions for broadening participation in the life sciences. PMID:27543632

  18. The HERMES recoil photon-detector and nuclear p{sub t}-Broadening at HERMES

    Energy Technology Data Exchange (ETDEWEB)

    Haarlem, Y. van

    2007-09-15

    The first part of this work consists of hardware research and development done in order to construct and test a photon-detector as one of the three detectors of the HERMES recoil detector. The HERMES recoil detector consists of a target cell, a silicon-detector, a scintillating fiber tracker, and a photon-detector. All are inside a super-conducting magnet. The silicon detector uses energy deposition to determine the momentum of the particle because in its energy range the energy deposition is an unambiguous function of the momentum of the particle. The scintillating fiber tracker is located outside the beam-vacuum and is surrounded by the photon-detector. It consists of two barrels with layers of scintillating fibers. It detects particles by converting their energy deposition into light. It measures two space points of a charged particle and from the bending of the assigned track (in the magnetic field provided by the super-conducting magnet) a momentum measurement can be derived. The photon-detector is located between the scintillating fiber tracker and the magnet. It consists (from the inside out) of three layers of tungsten showering material followed by scintillating strips. The second part of this work is an analysis performed concerning the transverse momentum broadening of hadrons produced in deep-inelastic scattering on a nuclear target compared to a D target. (orig.)

  19. Fabrication of a 2-DOF electromagnetic energy harvester with in-phase vibrational bandwidth broadening

    Science.gov (United States)

    Chen, Shih-Jui; Wu, Jia-Yin

    2016-09-01

    A vibration structure with two-degrees-of-freedom is proposed to increase the usable bandwidth of a micromachined electromagnetic energy harvester. Compared with the structure of a pure cantilever harvester, the proposed structure is formed by integrating a spiral diaphragm into a U-shaped cantilever diaphragm. By performing finite element analysis, the resonance frequencies of the two diaphragms are designed with a slight shift, both lower than 300 Hz. In addition, to achieve output bandwidth broadening, electroplated copper coils on the spiral and the U-shaped cantilever are coupled and the connection sequences of the coupled coils are arranged such that single- or duo-mode tuning of the energy harvester can be realized. The harvester delivers powers of 22.1 and 21.5 nW at two resonance frequencies of 211 and 274 Hz, respectively, in the duo-mode operation. The proposed spiral–cantilever coupled energy harvester has lower resonance frequencies and broader bandwidth than a pure cantilever-type harvester of equal area, and can therefore harvest more energy from the environment.

  20. Broadening the neutralizing capacity of a family of antibody fragments against different toxins from Mexican scorpions.

    Science.gov (United States)

    Rodríguez-Rodríguez, Everardo Remi; Olamendi-Portugal, Timoteo; Serrano-Posada, Hugo; Arredondo-López, Jonathan Noé; Gómez-Ramírez, Ilse; Fernández-Taboada, Guillermo; Possani, Lourival D; Anguiano-Vega, Gerardo Alfonso; Riaño-Umbarila, Lidia; Becerril, Baltazar

    2016-09-01

    New approaches aimed at neutralizing the primary toxic components present in scorpion venoms, represent a promising alternative to the use of antivenoms of equine origin in humans. New potential therapeutics developed by these approaches correspond to neutralizing antibody fragments obtained by selection and maturation processes from libraries of human origin. The high sequence identity shared among scorpion toxins is associated with an important level of cross reactivity exhibited by these antibody fragments. We have exploited the cross reactivity showed by single chain variable antibody fragments (scFvs) of human origin to re-direct the neutralizing capacity toward various other scorpion toxins. As expected, during these evolving processes several variants derived from a parental scFv exhibited the capacity to simultaneously recognize and neutralize different toxins from Centruroides scorpion venoms. A sequence analyses of the cross reacting scFvs revealed that specific mutations are responsible for broadening their neutralizing capacity. In this work, we generated a set of new scFvs that resulted from the combinatorial insertion of these point mutations. These scFvs are potential candidates to be part of a novel recombinant antivenom of human origin that could confer protection against scorpion stings. A remarkable property of one of these new scFvs (ER-5) is its capacity to neutralize at least three different toxins and its complementary capacity to neutralize the whole venom from Centruroides suffusus in combination with a second scFv (LR), which binds to a different epitope shared by Centruroides scorpion toxins.

  1. Confinement and inhomogeneous broadening effects in the quantum oscillatory magnetization of quantum dot ensembles

    International Nuclear Information System (INIS)

    We report on the magnetization of ensembles of etched quantum dots with a lateral diameter of 460 nm, which we prepared from InGaAs/InP heterostructures. The quantum dots exhibit 1/B-periodic de-Haas–van-Alphen-type oscillations in the magnetization M(B) for external magnetic fields B  >  2 T, measured by torque magnetometry at 0.3 K. We compare the experimental data to model calculations assuming different confinement potentials and including ensemble broadening effects. The comparison shows that a hard wall potential with an edge depletion width of 100 nm explains the magnetic behavior. Beating patterns induced by Rashba spin–orbit interaction (SOI) as measured in unpatterned and nanopatterned InGaAs/InP heterostructures are not observed for the quantum dots. From our model we predict that signatures of SOI in the magnetization could be observed in larger dots in tilted magnetic fields. (paper)

  2. Overcoming power broadening of the quantum dot emission in a pure wurtzite nanowire

    Science.gov (United States)

    Reimer, M. E.; Bulgarini, G.; Fognini, A.; Heeres, R. W.; Witek, B. J.; Versteegh, M. A. M.; Rubino, A.; Braun, T.; Kamp, M.; Höfling, S.; Dalacu, D.; Lapointe, J.; Poole, P. J.; Zwiller, V.

    2016-05-01

    One of the key challenges in developing quantum networks is to generate single photons with high brightness, purity, and long temporal coherence. Semiconductor quantum dots potentially satisfy these requirements; however, due to imperfections in the surrounding material, the coherence generally degrades with increasing excitation power yielding a broader emission spectrum. Here we overcome this power-broadening regime and demonstrate an enhanced coherence at exciton saturation where the detected count rates are highest. We detect single-photon count rates of 460 000 counts per second under pulsed laser excitation while maintaining a single-photon purity greater than 99%. Importantly, the enhanced coherence is attained with quantum dots in ultraclean wurtzite InP nanowires, where the surrounding charge traps are filled by exciting above the wurtzite InP nanowire band gap. By raising the excitation intensity, the number of possible charge configurations in the quantum dot environment is reduced, resulting in a narrower emission spectrum. Via Monte Carlo simulations we explain the observed narrowing of the emission spectrum with increasing power. Cooling down the sample to 300 mK, we further enhance the single-photon coherence twofold as compared to operation at 4.5 K, resulting in a homogeneous coherence time, T2, of 1.2 ns, and two-photon interference visibility as high as 83% under strong temporal postselection (˜5 % without temporal postselection).

  3. Using a Transdisciplinary Interpretive Lens to Broaden Reflections on Alleviating Poverty and Promoting Decent Work.

    Science.gov (United States)

    Di Fabio, Annamaria; Maree, Jacobus G

    2016-01-01

    This article aims to broaden current reflections on definitions of decent work and poverty using a transdisciplinary interpretive lens comprising philosophical, juridical, economic, sociological, and psychological understandings. We (the authors) undertook an adapted systematic qualitative review to gather data on different perspectives on decent work and poverty. The article summarizes and compares reflections on the two constructs and proposes an enhancement of the current definition of decent work. The aim is to facilitate the identification and development of new research and intervention projects that can be implemented to promote fair and sustainable economic development, the provision of decent work, and the reduction of poverty globally. We believe that challenges should be dealt with pro-actively rather than reactively and that intervening at the level of primary prevention should lie at the heart of any strategy to promote decent work and alleviate poverty. Radical intervention is needed to ensure that future generations not only survive but develop, grow, and express themselves meaningfully through decent work. PMID:27148115

  4. Using a Transdisciplinary Interpretive Lens to Broaden Reflections on Alleviating Poverty and Promoting Decent Work

    Directory of Open Access Journals (Sweden)

    Annamaria eDi Fabio

    2016-04-01

    Full Text Available This article aims to broaden current reflections on definitions of decent work and poverty using a transdisciplinary interpretive lens comprising philosophical, juridical, economic, sociological, and psychological understandings. We (the authors undertook an adapted systematic qualitative review to gather data on different perspectives on decent work and poverty. The article summarizes and compares reflections on the two constructs and proposes an enhancement of the current definition of decent work. The aim is to facilitate the identification and development of new research and intervention projects that can be implemented to promote fair and sustainable economic development, the provision of decent work, and the reduction of poverty globally. We believe that challenges should be dealt with pro-actively rather than reactively and that intervening at the level of primary prevention should lie at the heart of any strategy to promote decent work and alleviate poverty. Radical intervention is needed to ensure that future generations not only survive but develop, grow, and express themselves meaningfully through decent work

  5. Broadening perspectives on trauma and recovery: a socio-interpersonal view of PTSD.

    Science.gov (United States)

    Maercker, Andreas; Hecker, Tobias

    2016-01-01

    Posttraumatic stress disorder (PTSD) is one of the very few mental disorders that requires by definition an environmental context-a traumatic event or events-as a precondition for diagnosis. Both trauma sequelae and recovery always occur in the context of social-interpersonal contexts, for example, in interaction with a partner, family, the community, and the society. The present paper elaborates and extends the social-interpersonal framework model of PTSD. This was developed to complement other intrapersonally focused models of PTSD, which emphasize alterations in an individual's memory, cognitions, or neurobiology. Four primary reasons for broadening the perspective from the individual to the interpersonal-societal contexts are discussed. The three layers of the model (social affects, close relationships, and culture and society) are outlined. We further discuss additional insights and benefits of the social-interpersonal perspective for the growing field of research regarding resilience after traumatic experiences. The paper closes with an outlook on therapy approaches and interventions considering this broader social-interpersonal perspective on PTSD. PMID:26996533

  6. Broadening perspectives on trauma and recovery: a socio-interpersonal view of PTSD†

    Directory of Open Access Journals (Sweden)

    Andreas Maercker

    2016-03-01

    Full Text Available Posttraumatic stress disorder (PTSD is one of the very few mental disorders that requires by definition an environmental context—a traumatic event or events—as a precondition for diagnosis. Both trauma sequelae and recovery always occur in the context of social–interpersonal contexts, for example, in interaction with a partner, family, the community, and the society. The present paper elaborates and extends the social–interpersonal framework model of PTSD. This was developed to complement other intrapersonally focused models of PTSD, which emphasize alterations in an individual's memory, cognitions, or neurobiology. Four primary reasons for broadening the perspective from the individual to the interpersonal–societal contexts are discussed. The three layers of the model (social affects, close relationships, and culture and society are outlined. We further discuss additional insights and benefits of the social–interpersonal perspective for the growing field of research regarding resilience after traumatic experiences. The paper closes with an outlook on therapy approaches and interventions considering this broader social–interpersonal perspective on PTSD.

  7. Broadening the trans-contextual model of motivation: A study with Spanish adolescents.

    Science.gov (United States)

    González-Cutre, D; Sicilia, Á; Beas-Jiménez, M; Hagger, M S

    2014-08-01

    The original trans-contextual model of motivation proposed that autonomy support from teachers develops students' autonomous motivation in physical education (PE), and that autonomous motivation is transferred from PE contexts to physical activity leisure-time contexts, and predicts attitudes, perceived behavioral control and subjective norms, and forming intentions to participate in future physical activity behavior. The purpose of this study was to test an extended trans-contextual model of motivation including autonomy support from peers and parents and basic psychological needs in a Spanish sample. School students (n = 400) aged between 12 and 18 years completed measures of perceived autonomy support from three sources, autonomous motivation and constructs from the theory of planned behavior at three different points in time and in two contexts, PE and leisure-time. A path analysis controlling for past physical activity behavior supported the main postulates of the model. Autonomous motivation in a PE context predicted autonomous motivation in a leisure-time physical activity context, perceived autonomy support from teachers predicted satisfaction of basic psychological needs in PE, and perceived autonomy support from peers and parents predicted need satisfaction in leisure-time. This study provides a cross-cultural replication of the trans-contextual model of motivation and broadens it to encompass basic psychological needs.

  8. Dams and Displacement: Raising the Standards and Broadening the Research Agenda

    Directory of Open Access Journals (Sweden)

    Brooke McDonald-Wilmsen

    2010-06-01

    Full Text Available The World Commission on Dams provided an analytical overview of the cumulative effects of years of dam development. A lack of commitment or capacity to cope with displacement or to consider the civil rights of, or risks to, displaced people led to the impoverishment and suffering of tens of millions and growing opposition to dams by affected communities worldwide. However, after the WCD, little has changed for the better in terms of resettlement policies. In fact, the standards of key agencies, like the Asian Development Bank, have been lowered and diluted compared to prior policies. Dam-induced development and displacement are stifled by a 'managerialist' approach to planning, in which solutions are sought internally and subordinated to the economics that underpins the existence of the project. The aim of successful resettlement is to prevent impoverishment and to enable displaced people to share in the project’s benefits. Within the field of dam-induced resettlement, this is a lofty goal rarely achieved. However, in other fields of resettlement, such as refugee studies and adaptation to environmental change, such a goal is regarded as a minimum standard. In this paper we seek to broaden the research agenda on dam-induced resettlement and to raise the standards of development projects that entail resettlement. We do this by importing some of the considerations and concerns from practice and research from the fields of refugee studies and adaptation to environmental change.

  9. Phonon characteristics of high Tc superconductors from neutron Doppler broadening measurements

    International Nuclear Information System (INIS)

    Statistical information on the phonon frequency spectrum of materials can be measured by neutron transmission techniques if they contain nuclei with low energy resonances, narrow enough to be Doppler-broadened, in their neutron cross sections. The authors have carried out some measurements using this technique for materials of the lanthanum barium cuprate class, La2-xBaxCuO4. Two samples with slightly different concentrations of oxygen, one being superconductive, the other not, were examined. Pure lanthanum cuprate was also measured. Lanthanum, barium and copper all have relatively low energy narrow resonances. Thus it should be possible to detect differences in the phonons carried by different kinds of atom in the lattice. Neutron cross section measurements have been made with high energy resolution and statistical precision on the 59m flight path of LANSCE, the pulsed spallation neutron source at Los Alamos National Laboratory. Measurements on all three materials were made over a range of temperatures from 15K to 300K, with small steps through the critical temperature region near 27K. No significant changes in the mean phonon energy of the lanthanum atoms were observed near the critical temperature of the super-conducting material. It appears however that the mean phonon energy of lanthanum in the superconductor is considerably higher than that in the non-superconductors. The samples used in this series of experiments were too thin in barium and copper to determine anything significant about their phonon spectra

  10. On the consistency between positron annihilation lifetime and Doppler broadening results in polypropylene

    Energy Technology Data Exchange (ETDEWEB)

    Djourelov, N. [Department of Subatomic and Rad. Physics, Ghent University, Proeftuinstraat 86, 9000 Ghent (Belgium); Institute of Nuclear Research and Nuclear Energy, 72 Tzarigradsko Shoosse, 1784 Sofia (Bulgaria); Dauwe, C. [Department of Subatomic and Rad. Physics, Ghent University, Proeftuinstraat 86, 9000 Ghent (Belgium); Palacio, C.A. [Department of Subatomic and Rad. Physics, Ghent University, Proeftuinstraat 86, 9000 Ghent (Belgium); Institute of Physics, University of Antioquia, A. A. 1226, Medellin (Colombia); Laforest, N. [Department of Subatomic and Rad. Physics, Ghent University, Proeftuinstraat 86, 9000 Ghent (Belgium); University of Savoie, Batiment IUT, 73376 Le Bourget-du-lac Cedex (France); Bas, C. [University of Savoie, Batiment IUT, 73376 Le Bourget-du-lac Cedex (France)

    2007-07-01

    Polypropylene samples were measured as a function of the source exposure time at 20 K and as a function of the temperature (20-400 K) simultaneously by Positron Annihilation Lifetime (PAL) and Doppler Broadening (DB) spectroscopy. The peak shape parameter (S) measured by DB can be calculated as a sum of contributions of specific parameters corresponding to each positron state. The contributions are obtained by analysis of the PAL spectra. The confinement of positronium (Ps) in a free volume hole (FVH) determines the self annihilation shape parameter S{sub sa} of the para-Ps, the pick-off annihilation lifetime {tau}{sub po}, and supposes FVH size-dependence of the pick-off shape parameter S{sub po}. The ortho-Ps lifetime and shape parameters are used to compute S{sub sa}. In this way, the temperature and time dependences of the S parameter are modelled. The fit of this model to the experimental S parameter shows a stronger dependence of the S{sub po} on the FVH size (R) than the one as expected by taking into account only the Ps momentum. This result suggests that the penetration of Ps into the walls of the FVH must be properly considered and that the penetration depth depends on R itself. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Using a Transdisciplinary Interpretive Lens to Broaden Reflections on Alleviating Poverty and Promoting Decent Work

    Science.gov (United States)

    Di Fabio, Annamaria; Maree, Jacobus G.

    2016-01-01

    This article aims to broaden current reflections on definitions of decent work and poverty using a transdisciplinary interpretive lens comprising philosophical, juridical, economic, sociological, and psychological understandings. We (the authors) undertook an adapted systematic qualitative review to gather data on different perspectives on decent work and poverty. The article summarizes and compares reflections on the two constructs and proposes an enhancement of the current definition of decent work. The aim is to facilitate the identification and development of new research and intervention projects that can be implemented to promote fair and sustainable economic development, the provision of decent work, and the reduction of poverty globally. We believe that challenges should be dealt with pro-actively rather than reactively and that intervening at the level of primary prevention should lie at the heart of any strategy to promote decent work and alleviate poverty. Radical intervention is needed to ensure that future generations not only survive but develop, grow, and express themselves meaningfully through decent work PMID:27148115

  12. Phonon characteristics of high {Tc} superconductors from neutron Doppler broadening measurements

    Energy Technology Data Exchange (ETDEWEB)

    Trela, W.J.; Kwei, G.H.; Lynn, J.E. [Los Alamos National Lab., NM (United States); Meggers, K. [Univ. of Kiel (Germany)

    1994-12-01

    Statistical information on the phonon frequency spectrum of materials can be measured by neutron transmission techniques if they contain nuclei with low energy resonances, narrow enough to be Doppler-broadened, in their neutron cross sections. The authors have carried out some measurements using this technique for materials of the lanthanum barium cuprate class, La{sub 2{minus}x}Ba{sub x}CuO{sub 4}. Two samples with slightly different concentrations of oxygen, one being superconductive, the other not, were examined. Pure lanthanum cuprate was also measured. Lanthanum, barium and copper all have relatively low energy narrow resonances. Thus it should be possible to detect differences in the phonons carried by different kinds of atom in the lattice. Neutron cross section measurements have been made with high energy resolution and statistical precision on the 59m flight path of LANSCE, the pulsed spallation neutron source at Los Alamos National Laboratory. Measurements on all three materials were made over a range of temperatures from 15K to 300K, with small steps through the critical temperature region near 27K. No significant changes in the mean phonon energy of the lanthanum atoms were observed near the critical temperature of the super-conducting material. It appears however that the mean phonon energy of lanthanum in the superconductor is considerably higher than that in the non-superconductors. The samples used in this series of experiments were too thin in barium and copper to determine anything significant about their phonon spectra.

  13. Analysis of Postdoctoral Training Outcomes That Broaden Participation in Science Careers.

    Science.gov (United States)

    Rybarczyk, Brian J; Lerea, Leslie; Whittington, Dawayne; Dykstra, Linda

    2016-01-01

    Postdoctoral training is an optimal time to expand research skills, develop independence, and shape career trajectories, making this training period important to study in the context of career development. Seeding Postdoctoral Innovators in Research and Education (SPIRE) is a training program that balances research, teaching, and professional development. This study examines the factors that promote the transition of postdocs into academic careers and increase diversity in science, technology, engineering, and mathematics. Data indicate that SPIRE scholars (n = 77) transition into faculty positions at three times the national average with a greater proportion of underrepresented racial minorities (URMs) and females represented among SPIRE scholars. Logistic regression models indicate that significant predictors are the intended career track at the start of the postdoctoral training and the number of publications. Factors necessary for successful transition are teaching experience as independent instructors, professional development opportunities, and the experience of balancing teaching with research. Scholars' continued commitment to increasing diversity in their faculty roles was demonstrated by their attainment of tenure-track positions at minority-serving institutions, continued mentorship of URMs, and engagement with diversity initiatives. These results suggest that a postdoctoral program structured to include research, teaching, and diversity inclusion facilitates attainment of desired academic positions with sustained impacts on broadening participation. PMID:27543634

  14. DYNC2LI1 mutations broaden the clinical spectrum of dynein-2 defects.

    Science.gov (United States)

    Kessler, Kristin; Wunderlich, Ina; Uebe, Steffen; Falk, Nathalie S; Gießl, Andreas; Brandstätter, Johann Helmut; Popp, Bernt; Klinger, Patricia; Ekici, Arif B; Sticht, Heinrich; Dörr, Helmuth-Günther; Reis, André; Roepman, Ronald; Seemanová, Eva; Thiel, Christian T

    2015-01-01

    Skeletal ciliopathies are a heterogeneous group of autosomal recessive osteochondrodysplasias caused by defects in formation, maintenance and function of the primary cilium. Mutations in the underlying genes affect the molecular motors, intraflagellar transport complexes (IFT), or the basal body. The more severe phenotypes are caused by defects of genes of the dynein-2 complex, where mutations in DYNC2H1, WDR34 and WDR60 have been identified. In a patient with a Jeune-like phenotype we performed exome sequencing and identified compound heterozygous missense and nonsense mutations in DYNC2LI1 segregating with the phenotype. DYNC2LI1 is ubiquitously expressed and interacts with DYNC2H1 to form the dynein-2 complex important for retrograde IFT. Using DYNC2LI1 siRNA knockdown in fibroblasts we identified a significantly reduced cilia length proposed to affect cilia function. In addition, depletion of DYNC2LI1 induced altered cilia morphology with broadened ciliary tips and accumulation of IFT-B complex proteins in accordance with retrograde IFT defects. Our results expand the clinical spectrum of ciliopathies caused by defects of the dynein-2 complex.

  15. Recent Approaches for Broadening the Spectral Bandwidth in Resonant Cavity Optoelectronic Devices

    Directory of Open Access Journals (Sweden)

    Gun Wu Ju

    2015-01-01

    Full Text Available Resonant cavity optoelectronic devices, such as vertical cavity surface emitting lasers (VCSELs, resonant cavity enhanced photodetectors (RCEPDs, and electroabsorption modulators (EAMs, show improved performance over their predecessors by placing the active device structure inside a resonant cavity. The effect of the optical cavity, which allows wavelength selectivity and enhancement of the optical field due to resonance, allows the devices to be made thinner and therefore faster, while simultaneously increasing the quantum efficiency at the resonant wavelengths. However, the narrow spectral bandwidth significantly reduces operating tolerances, which leads to severe problems in applications such as optical communication, imaging, and biosensing. Recently, in order to overcome such drawbacks and/or to accomplish multiple functionalities, several approaches for broadening the spectral bandwidth in resonant cavity optoelectronic devices have been extensively studied. This paper reviews the recent progress in techniques for wide spectral bandwidth that include a coupled microcavity, asymmetric tandem quantum wells, and high index contrast distributed Bragg-reflectors. This review will describe design guidelines for specific devices together with experimental considerations in practical applications.

  16. Analysis of Postdoctoral Training Outcomes That Broaden Participation in Science Careers

    Science.gov (United States)

    Rybarczyk, Brian J.; Lerea, Leslie; Whittington, Dawayne; Dykstra, Linda

    2016-01-01

    Postdoctoral training is an optimal time to expand research skills, develop independence, and shape career trajectories, making this training period important to study in the context of career development. Seeding Postdoctoral Innovators in Research and Education (SPIRE) is a training program that balances research, teaching, and professional development. This study examines the factors that promote the transition of postdocs into academic careers and increase diversity in science, technology, engineering, and mathematics. Data indicate that SPIRE scholars (n = 77) transition into faculty positions at three times the national average with a greater proportion of underrepresented racial minorities (URMs) and females represented among SPIRE scholars. Logistic regression models indicate that significant predictors are the intended career track at the start of the postdoctoral training and the number of publications. Factors necessary for successful transition are teaching experience as independent instructors, professional development opportunities, and the experience of balancing teaching with research. Scholars’ continued commitment to increasing diversity in their faculty roles was demonstrated by their attainment of tenure-track positions at minority-serving institutions, continued mentorship of URMs, and engagement with diversity initiatives. These results suggest that a postdoctoral program structured to include research, teaching, and diversity inclusion facilitates attainment of desired academic positions with sustained impacts on broadening participation. PMID:27543634

  17. A new calculation method of light excitation of atoms with inhomogeneous ling broadening%谱线非均匀展宽条件下原子激发的计算方法

    Institute of Scientific and Technical Information of China (English)

    唐柯鸿; 王立军

    2011-01-01

    原子吸收谱线展宽对原子光激发有较大的影响.在速率方程理论中人们通常将原子谱线的均匀展宽和非均匀展宽都归于原子谱线的线型函数.本文提出了一种将均匀展宽和非均匀展宽区别处理的原子激发计算方法,并指出当激发光与原子作用时间短于原子热运动平均碰撞时间时,这种区别对待均匀展宽和非均匀展宽的做法是十分必要的.并将文中提出的新方法应用于一个二能级原子跃迁过程的计算,计算结果显示两种方法具有很大差别.%One of the important factors that can significantly affect the light excitation process of an atom is the width of the related absorption line.Traditionally, in the rate equation theory the contributions of both homogeneous and inhomogeneous line broadening mechanisms are equally taken into account of the line shape function.In this paper a new approach, in which the homogeneous and inhomogeneous line broadening mechanisms are treated differently, is presented and it is pointed out that this approach is the sole right one in the case when the duration of an exciting light pulse is shorter than the mean collision time of atoms.The new approach is applied to a two energy level system and the results are very different from that of the traditional treatment.

  18. Statistical correlation of spectral broadening in VLF transmitter signal and low-frequency ionospheric turbulence from observation on DEMETER satellite

    Directory of Open Access Journals (Sweden)

    A. Rozhnoi

    2008-10-01

    Full Text Available In our earlier papers we have found the effect of VLF transmitter signal depression over epicenters of the large earthquakes from observation on the French DEMETER satellite that can be considered as new method of global diagnostics of seismic influence on the ionosphere. At present paper we investigate a possibility VLF signal-ionospheric turbulence interaction using additional characteristic of VLF signal-spectrum broadening. This characteristic is important for estimation of the interaction type: linear or nonlinear scattering. Our main results are the following:
    – There are two zones of increased spectrum broadening, which are centered near magnetic latitudes Φ=±10° and Φ=±40°. Basing on the previous case study research and ground ionosonde registrations, probably it is evidence of nonlinear (active scattering of VLF signal on the ionospheric turbulence. However occurrence rate of spectrum broadening in the middle-latitude area is higher than in the near-equatorial zone (~15–20% in comparison with ~100% in former area that is probably coincides with the rate of ionospheric turbulence.
    – From two years statistics of observation in the selected 3 low-latitude regions and 1 middle-latitude region inside reception area of VLF signal from NWC transmitter we find a correlation of spectrum broadening neither with ion-cyclotron noise (f=150–500 Hz, which possibly means poor representation of the turbulence by the noise due to its mixture with natural ELF emission (which correlates with whistler, nor with magnetic storm activity.
    – We find rather evident correlation of ion-cyclotron frequency noise, VLF signal depression and weak correlation of spectrum broadening with seismicity in the middle-latitude region over Japan. But in the low-latitude regions we do not find such a correlation. Statistical decrease of VLF signal supports our previous case study results. However rather weak spectrum broadening

  19. Understanding and diminishing the extra-column band broadening effects in supercritical fluid chromatography.

    Science.gov (United States)

    De Pauw, Ruben; Shoykhet Choikhet, Konstantin; Desmet, Gert; Broeckhoven, Ken

    2015-07-17

    Supercritical fluid chromatography, where a low-viscosity mobile phase such as carbon dioxide is used, proves to be an excellent technique for fast and efficient separations, especially when sub-2μm particles are used. However, to achieve high velocities when using these small particles, and in order to stay within the flow rate range of current SFC-instruments, narrow columns (e.g. 2.1mm ID) must be used. Unfortunately, state-of-the-art instrumentation is limiting the full separation power of these narrower columns due to significant extra-column band broadening effects. The present work identifies and quantifies the different contributions to extra-column band broadening in SFC such as the influence of the sample solvent, injection volume, extra-column volumes and detector cell volume/design. When matching the sample solvent to the mobile phase in terms of elution strength and polarity (e.g. using hexane/ethanol/isopropanol 85/10/5vol%) and lowering the injection volume to 0.4μL, the plate count can be increased from 7600 to 21,300 for a low-retaining compound (k'=2.3) on a 2.1mm×150mm column (packed with 1.8μm particles). The application of a water/acetonitrile mixture as sample solvent was also investigated. It was found that when the volumetric ratio of water/acetonitrile was optimized, only a slightly lower plate count was measured compared to the hexane-based solvent when minimizing injection and extra-column volume. This confirms earlier results that water/acetonitrile can be used if water-soluble samples are considered or when a less volatile solvent is preferred. Minimizing the ID of the connection capillaries from 250 to 65μm, however, gives no further improvement in obtained efficiency for early-eluting compounds when a standard system configuration with optimized sample solvent was used. When switching to a state-of-the-art detector design with reduced (dispersion) volume (1.7-0.6μL), an increase in plate count is observed (from 11,000 to 14

  20. Positron annihilation Doppler broadening spectroscopy study on Fe-ion irradiated NHS steel

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Huiping [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Wang, Zhiguang, E-mail: zhgwang@impcas.ac.cn [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Gao, Xing; Cui, Minghuan; Li, Bingsheng; Sun, Jianrong; Yao, Cunfeng; Wei, Kongfang; Shen, Tielong; Pang, Lilong; Zhu, Yabin [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Li, Yuanfei; Wang, Ji [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); University of Lanzhou, Lanzhou 730000 (China); Song, Peng [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhang, Peng; Cao, Xingzhong [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)

    2015-02-01

    Highlights: • NHS steel was irradiated by 3.25 MeV Fe ions to different fluences at room temperature and 723 K. • The evolution of vacancy type defects is studied through positron annihilation spectroscopy. • The concentration gradient of SIA can induce the decrease of S value with increasing fluence at high temperature. - Abstract: In order to study the evolution of irradiation-induced vacancy-type defects at different irradiation fluences and temperatures, a new type of ferritic/martensitic (F/M) steel named NHS (Novel High Silicon) was irradiated by 3.25 MeV Fe-ion at room temperature and 723 K to fluences of 4.3 × 10{sup 15} and 1.7 × 10{sup 16} ions/cm{sup 2}. After irradiation, vacancy-type defects were investigated with variable-energy positron beam Doppler broadening spectra. Energetic Fe-ions produced a large number of vacancy-type defects in the NHS steel, but one single main type of vacancy-type defect was observed in both unirradiated and irradiated samples. The concentration of vacancy-type defects decreased with increasing temperature. With the increase of irradiation fluence, the concentration of vacancy-type defects increased in the sample irradiated at RT, whereas for the sample irradiated at 723 K, it decreased. The enhanced recombination between vacancies and excess interstitial Fe atoms from deeper layers, and high diffusion rate of self-interstitial atoms further improved by diffusion via grain boundary and dislocations at high temperature, are thought to be the main reasons for the reversed trend of vacancy-type defects between the samples irradiated at RT and 723 K.

  1. An International Coastline Collaboratory to Broaden Scientific Impacts of a Subduction Zone Observatory

    Science.gov (United States)

    Bodin, P.

    2015-12-01

    A global Subduction Zone Observatory (SZO) presents an exciting opportunity to broaden involvement in scientific research and to ensure multidisciplinary impact. Most subduction zones feature dynamic interactions of the seafloor, the coastline, and the onshore environments also being perturbed by global climate change. Tectonic deformation, physical environment changes (temperature and chemistry), and resulting ecological shifts (intertidal population redistribution, etc.) are all basic observables for important scientific investigation. Yet even simple baseline studies like repeated transects of intertidal biological communities are rare. A coordinated program of such studies would document the local variability across time and spatial scales, permit comparisons with other subducting coastlines, and extend the reach and importance of other SZO studies. One goal is to document the patterns, and separate the component causes of, coastal uplift and subsidence and ecological response to a subduction zone earthquake using a database of pre-event biological and surveying observations. Observations would be directed by local scientists using students and trained volunteers as observers, under the auspices of local educational entities and using standardized sampling and reporting methods. The observations would be added to the global, Internet-accessible, database for use by the entire scientific community. Data acquisition and analysis supports the educational missions of local schools and universities, forming the basis for educational programs. All local programs would be coordinated by an international panel convened by the SZO. The facility would include a web-hosted lecture series and an annual web conference to aid organization and collaboration. Small grants could support more needy areas. This SZO collaboratory advances not only scientific literacy, but also multinational collaboration and scholarship, and (most importantly) produces important scientific results.

  2. Broadening the Frequency Bandwidth of Piezoelectric Energy Harvesters Using Coupled Linear Resonators

    Science.gov (United States)

    Sadeqi, Soheil

    The desire to reduce power consumption of current integrated circuits has led design engineers to focus on harvesting energy from free ambient sources such as vibrations. The energy harvested this way can eliminate the need for battery replacement, particularly, in low-energy remote sensing and wireless devices. Currently, most vibration-based energy harvesters are designed as linear resonators, therefore, they have a narrow resonance frequency. The optimal performance of such harvesters is achieved only when their resonance frequency is matched with the ambient excitation. In practice, however, a slight shift of the excitation frequency will cause a dramatic reduction in their performance. In the majority of cases, the ambient vibrations are totally random with their energy distributed over a wide frequency spectrum. Thus, developing techniques to extend the bandwidth of vibration-based energy harvesters has become an important field of research in energy harvesting systems. This thesis first reviews the broadband vibration-based energy harvesting techniques currently known in some detail with regard to their merits and applicability under different circumstances. After that, the design, fabrication, modeling and characterization of three new piezoelectric-based energy harvesting mechanism, built typically for rotary motion applications, is discussed. A step-by-step procedure is followed in order to broaden the bandwidth of such energy harvesters by introducing a coupled spring-mass system attached to a PZT beam undergoing rotary motion. It is shown that the new strategies can indeed give rise to a wide-band frequency response making it possible to fine-tune their dynamical response. The numerical results are shown to be in good agreement with the experimental data as far as the frequency response is concerned.

  3. Electron irradiation effect of polyurethane using coincidence doppler-broadening spectroscopy

    International Nuclear Information System (INIS)

    Full text: To understand the electron irradiation effects on polymer, polyether-urethane (ETPU) samples of 2mm in thickness and 10mm in diameter were irradiated by a 1.8MeV electron beam with beam current of 3 ma at room temperature. The irradiated doses are 5 kGy, 10 kGy, 15 kGy, 30 kGy, 100 kGy and 150 kGy. ETPU was manufactured by mixing PTMG-100, TDI-100 and MOCA. The momentum density distributions (MMDs) of electrons taking part in the annihilation processes of positron-electron pairs in ETPU have been measured by coincidence Doppler-broadening spectroscopy (CDBS). By presenting the ratio of the counts in every channel of the measured CDB spectrum to the corresponding counts from a reference spectrum (pristine ETPU), we observed that the change in MMDs is not significant for doses lower than 10 kGy. However, high momentum part of MMDs exhibit an obvious decrease for dose exceeding 15 kGy and then slowly down to steady with doses until 150 kGy. This valley occurs at around 15x103mοc and is well known as oxygen-specific, indicative of a less positron trapping by oxygen atoms in some samples of higher dose radiation. It is postulated that the radiation will break the crosslinkings, allowing the trace water and oxygen molecules to be released from the sample surface. Excess NCO groups in ETPU would crosslink with urethane and urea groups to produce allophanate and biuret groups. After receiving a certain amount of electron irradiation, crosslinked allophanate and biuret groups would produce degradation. Thus, residual water and oxygen trapped in ETPU by the crosslinking would diffuse out. However, the irradiation doses up to 150 kGy in this experiment are still not large enough to induce strong degradation of urethane and urea groups

  4. Broadening the Morphologic Spectrum of Bartonella henselae Lymphadenitis: Analysis of 100 Molecularly Characterized Cases.

    Science.gov (United States)

    Jabcuga, Christine E; Jin, Long; Macon, William R; Howard, Matthew T; Oliveira, Andre M; King, Rebecca L

    2016-03-01

    Bartonella henselae lymphadenitis, or cat-scratch lymphadenitis (CSL), is classically associated with stellate microabscesses, occasional giant cells, and extension of the inflammatory infiltrate into perinodal soft tissue. Availability of B. henselae molecular testing on tissue specimens has broadened our understanding of the morphologic variation in this disease. Here we sought to describe the histopathologic features of the largest series to date of molecularly proven CSL. B. henselae polymerase chain reaction-positive tissue specimens from 2010 to 2012 were identified, and hematoxylin and eosin slides were reviewed. A single-step 16S-23S rRNA-based polymerase chain reaction testing was used to identify B. henselae on formalin-fixed, paraffin-embedded tissues. A total of 100 B. henselae-positive cases were identified. The median age of the patients was 26.5 years (range, 1 to 69 y). Ninety-two percent of cases presented in lymph nodes, with 66% of these occurring above the diaphragm, most commonly in the cervical chain. Of 100 cases, 57 had classical CSL features of necrotizing granulomas with microabscesses, with or without surrounding palisading histiocytes. In contrast, 43/100 cases lacked the prototypical microabscesses of CSL including: 23 cases (53.5%) with features of fungal/mycobacterial lymphadenitis, 6 (14%) cases with features of Kikuchi lymphadenitis, and 4 cases (9.3%) with the classic histologic triad of toxoplasma lymphadenitis. In summary, B. henselae lymphadenitis may lack the typical microabscesses in almost half of cases and may closely mimic other reactive, especially infectious, lymphadenopathies. Given the lack of specificity of many of these features, a low threshold for B. henselae molecular testing on tissue is warranted in the appropriate clinical context. PMID:26551620

  5. A New Norm: Using Social Science to Create Disruptive Innovations for Broadening Participation in Physics

    Science.gov (United States)

    Smith, Jessi L.

    2016-03-01

    Norms often operate outside conscious awareness and limit broad participation in physics and STEM fields more generally. This presentation identifies several of these norms and provides empirically tested disruptions at three academic points: faculty, graduate, and undergraduate. First, is a focus on broadening the participation of women science faculty through an intervention aimed at supporting faculty search committees. Using a randomized control trail design, results show searches in the intervention were 6.3 times more likely to make an offer to a woman candidate, and these women were 5.8 times more likely to accept the offer from an intervention search. A diverse faculty can help disrupt the norms of their field's understanding about brilliance and effort, which can appeal to -or repel- potential graduate students. Using a randomized control trial design, recruitment materials for a science graduate program were manipulated to emphasize effort versus innate ability as the norm. Results show emphasizing effort as normal to achieve success in the male-dominated graduate program elevated women's motivation to purse and persist in graduate studies. Of course, before a student will consider graduate school, they must see themselves as a scientist. Data from a survey at three universities showed undergraduate women in physics lab classes were less likely to identify as a scientist when they were concerned about being stereotyped and could not see how physics was useful or helpful to society. Identifying and disrupting social norms can help create an inclusive learning and working context with far-reaching benefits. National Science Foundation Award HRD-1208831 and HRD-1036767.

  6. Broadened population-level frequency tuning in human auditory cortex of portable music player users.

    Directory of Open Access Journals (Sweden)

    Hidehiko Okamoto

    Full Text Available Nowadays, many people use portable players to enrich their daily life with enjoyable music. However, in noisy environments, the player volume is often set to extremely high levels in order to drown out the intense ambient noise and satisfy the appetite for music. Extensive and inappropriate usage of portable music players might cause subtle damages in the auditory system, which are not behaviorally detectable in an early stage of the hearing impairment progress. Here, by means of magnetoencephalography, we objectively examined detrimental effects of portable music player misusage on the population-level frequency tuning in the human auditory cortex. We compared two groups of young people: one group had listened to music with portable music players intensively for a long period of time, while the other group had not. Both groups performed equally and normally in standard audiological examinations (pure tone audiogram, speech test, and hearing-in-noise test. However, the objective magnetoencephalographic data demonstrated that the population-level frequency tuning in the auditory cortex of the portable music player users was significantly broadened compared to the non-users, when attention was distracted from the auditory modality; this group difference vanished when attention was directed to the auditory modality. Our conclusion is that extensive and inadequate usage of portable music players could cause subtle damages, which standard behavioral audiometric measures fail to detect in an early stage. However, these damages could lead to future irreversible hearing disorders, which would have a huge negative impact on the quality of life of those affected, and the society as a whole.

  7. Superluminal light propagation in a bi-chromatically Raman-driven and Doppler-broadened N-type 4-level atomic system

    CERN Document Server

    Bacha, Bakht Amin; Ahmad, Iftikhar

    2013-01-01

    We investigate the behavior of fast light pulse propagation in an N-type Doppler-broadened 4-level atomic system using double Raman gain processes. This system displays novel and interesting results of two controllable pairs of the double gain lines profile with a control field. The detailed physics of the processes are explored having multiple controllable anomalous regions in the medium. In this set up, the system exhibits significant enhancement in the probing Gaussian pulse through the medium as compared with Ref. [L. J. Wang, A. Kuzmich, and A. Dogariu, Nature \\textbf{406}, 227(2000)]. The advance time of the retrieved Gaussian pulse is always greater than the advance time studied in the above said experiment. We analyzed that the pulse propagating through the medium with larger negative group index, $7.32\\times10^8$, leaves the medium almost undistorted and sooner by time $76.12 \\ ms$ than the pulse which leaves the medium of Wang \\emph{et al.}. The Gaussian pulse always remains almost undistorted at ou...

  8. The broad iron Kalpha line of Cygnus X-1 as seen by XMM-Newton in the EPIC-pn modified timing mode

    CERN Document Server

    Duro, R; Wilms, J; Pottschmidt, K; Nowak, M A; Fritz, S; Kendziorra, E; Kirsch, M G F; Reynolds, C S; Staubert, R

    2011-01-01

    We present the analysis of the broadened, flourescent iron Kalpha line in simultaneous XMM-Newton and RXTE data from the black hole Cygnus X-1. The XMM-Newton data were taken in a modified version of the timing mode of the EPIC-pn camera. In this mode the lower energy threshold of the instrument is increased to 2.8 keV to avoid telemetry drop outs due to the brightness of the source, while at the same time preserving the signal-to-noise ratio in the Fe Kalpha band. We find that the best-fit spectrum consists of the sum of an exponentially cut off power-law and relativistically smeared, ionized reflection. The shape of the broadened Fe Kalpha feature is due to strong Compton broadening combined with relativistic broadening. Assuming a standard, thin accretion disk, the black hole is close to rotating maximally.

  9. Phase Control of Group Velocity in a Doppler-Broadened Λ-Type Three-Level System

    Science.gov (United States)

    Qiu, Tian-Hui; Xie, Min

    2016-06-01

    We theoretically investigate the phase control role on the group velocity of a weak probe field in a Doppler-broadened Λ-type three-level atomic system with the spontaneously generated coherence effect enhanced by an incoherence pump. We find that the absorption-dispersion of the probe field behaves phase and Doppler broadening-dependent phenomena, and testify that the quite large group index can be realized. The group velocity of the probe field can be switched from subluminal to superluminal or vice versa by modulating the relative phase of the two applied light fields. In contrast to the counterpropagating setting, the copropagating case is more suitable for the purpose considered in this paper due to the effectiveness of Doppler-free.

  10. Spectral Analysis of Quantum-Dash Lasers: Effect of Inhomogeneous Broadening of the Active-Gain Region

    KAUST Repository

    Khan, Mohammed Zahed Mustafa

    2012-05-01

    The effect of the active region inhomogeneity on the spectral characteristics of InAs/InP quantum-dash (Qdash) lasers is examined theoretically by solving the coupled set of carrier-photon rate equations. The inhomogeneity due to dash size or composition fluctuation is included in the model by considering dispersive energy states and characterized by a Gaussian envelope. In addition, the technique incorporates multilongitudinal photon modes and homogeneous broadening of the optical gain. The results predict a red shift in the central lasing wavelength of Qdash lasers on increasing the inhomogeneous broadening either explicitly or implicitly, which supports various experimental observations. The threshold current density and the lasing bandwidth are also found to increase. © 2012 IEEE.

  11. Influence of inhomogeneous broadening and deliberately introduced disorder on the width of the lasing spectrum of a quantum dot laser

    International Nuclear Information System (INIS)

    Analytical expressions for the shape and width of the lasing spectra of a quantum-dot (QD) laser in the case of a small (in comparison with the spectrum width) homogeneous broadening of the QD energy levels have been obtained. It is shown that the dependence of the lasing spectrum width on the output power at room temperature is determined by two dimensionless parameters: the width of QD distribution over the optical-transition energy, normalized to temperature, and the ratio of the optical loss to the maximum gain. The optimal dimensions of the laser active region have been found to obtain a specified width of the emission spectrum at a minimum pump current. The possibility of using multilayer structures with QDs to increase the lasing spectrum’s width has been analyzed. It is shown that the use of several arrays of QDs with deliberately variable optical-transition energies leads to broadening of the lasing spectra; some numerical estimates are presented.

  12. Coherence-controlled transparency and far-from-degenerate parametric gain in a strongly-absorbing Doppler-broadened medium

    CERN Document Server

    George, T F; George, Thomas F.

    2000-01-01

    An inversionless gain of anti-Stokes radiation above the oscillation threshold in an optically-dense far-from-degenerate double-Lambda Doppler-broadened medium accompanied by Stokes gain is predicted. The outcomes are illustrated with numerical simulations applied to sodium dimer vapor. Optical switching from absorption to gain via transparency controlled by a small variation of the medium and of the driving radiation parameters which are at a level less than one photon per molecule is shown.

  13. Distance learning education: What is its place in Broadening the radiography spectrum as we scale professional heights?

    International Nuclear Information System (INIS)

    One of the SORK's objective is to provide a forum for discussing topic issues with a view of enhancing the strategy for regional and continental integration in Africa as a prerequisite for meaningful and economic and social development with radiography professionals and services sharply in focus. the presentation examines the ability to cope up with this process; how far they are; what they need and how to boldly face up to the challenge if they have to broaden the radiography spectrum

  14. Extremely Nonlinear Optics Using Shaped Pulses Spectrally Broadened in an Argon- or Sulfur Hexafluoride-Filled Hollow-Core Fiber

    OpenAIRE

    Andreas Hoffmann; Michael Zürch; Christian Spielmann

    2015-01-01

    In this contribution we present a comparison of the performance of spectrally broadened ultrashort pulses using a hollow-core fiber either filled with argon or sulfur hexafluoride (SF6) for demanding pulse-shaping experiments. The benefits of both gases for pulse-shaping are studied in the highly nonlinear process of high-harmonic generation. In this setup, temporally shaping the driving laser pulse leads to spectrally shaping of the output extreme ultraviolet (XUV) spectrum, where total yie...

  15. Broadening the genetic base of Abyssinian mustard (Brassica carinata A. Braun) through introgression of genes from related allotetraploid species

    OpenAIRE

    Farooq A. Sheikh; Sashi Banga; Surindar S. Banga

    2014-01-01

    Brassica carinata (BBCC, 2n=34) has still to emerge as a major oilseed crop owing to poor agronomic attributes like long stature, long maturity duration and low seed yield. The restricted amount of genetic variability available in natural B. carinata necessitates utilization of new sources of variability for broadening its genetic base. Interspecific hybridization followed by selection in selfed and back cross progenies was employed to generate useful variability into B. carinata cv ˈPC5ˈ fro...

  16. Capitalizing on Education and Outreach (E/O) Expertise to Broaden Impacts (Invited)

    Science.gov (United States)

    Girguis, P. R.; Herren, C.; Decharon, A.

    2010-12-01

    Academic scientists have a number of avenues through which they can participate in education and outreach (E/O) programs to address the mandate for broader impacts. As a principal investigator (PI) at an R1 institution, I (Girguis) have both developed and participated in a variety of E/O programs that span the spectrum from ad hoc groups (e.g. informal high school internships in my laboratory) to regional efforts (e.g. Harvard’s Microbial Science Initiative) and national organizations (e.g. RIDGE 2000; Centers for Ocean Sciences Education Excellence, COSEE). Each of these E/O efforts required varying degrees of preparation and participation by my laboratory members (e.g. graduate students and postdoctoral researchers) and I, and yielded different outcomes and products. Ad hoc programs typically require a higher degree of effort on the part of the PI and have a high, though local, impact on the audience. These programs can be personally rewarding for the PI, who likely has played a major role in developing the program. In contrast, working with regional and national groups requires PIs to understand the nature of each program to successfully integrate within the existing structure. The net time and effort invested by scientists in larger-scale E/O efforts may be equal to that of ad hoc programs. However, interaction with high-quality program facilitators ensures that the outcomes are grounded in best educational practices and that outputs are educator-vetted, well maintained (online or through publications), and broadly disseminated. In addition, program facilitators also collect and analyze evaluation data to provide constructive feedback to PIs, enabling the latter to refine their presentation styles and content levels to improve future E/O efforts. Thus involvement with larger programs can effectively broaden one’s impact. During this presentation, we will present one scientist’s perspective on the advantages and limitations of these different modes of E

  17. IBP's Four-Prong Approach for Broadening Participation in the STEM Community

    Science.gov (United States)

    Ricciardi, L.; Fauver, A.; Johnson, A.; Detrick, L.; Siegfried, D.; Thomas, S.; Valaitis, S.

    2013-12-01

    The goal of the Institute for Broadening Participation (IBP) is to increase diversity in the Science, Technology, Engineering and Mathematics (STEM) workforce. As a freestanding non-profit dedicated to this work IBP is uniquely positioned to provide resources to faculty and students that individual institutions and disciplinary based programs cannot. Through its initial work with the NSF Integrative Graduate Education and Research Traineeship (IGERT), Research Experiences for Undergraduates (REU), and Alliance for Graduate Education and the Professoriate (AGEP) programs, IBP developed a four-pronged approach open to all members of the STEM community nationally for addressing the problem of underrepresentation: Synthesizing information - compiling and translating best practices into materials and resources accessible and useful to a broad national audience; Creating and maintaining strategic web resources - making information on programs, best practices, and references easily available to a wide audience including students, faculty, and administrators; Extensive face-to-face and virtual outreach - drawing constituents to the resources available via IBP that support students and faculty through the entire STEM pathway; and Catalyzing partnerships - cultivating a community of practice and culture of diversity, to reduce isolation among diversity practitioners, and to increase information sharing. IBP is also home to several successful initiatives that use both virtual and face-to-face components to bring together underrepresented students with established underrepresented and other scientists in academia, government and industry. These connections provide underrepresented students with supportive mentoring, networking opportunities, and professional skill development contributing to an overall improved retention rate of underrepresented students majoring in STEM degrees. IBP's initiatives include the NASA One Stop Shopping Initiative (NASA OSSI), Pathways to Ocean

  18. Pressure induced hyperfine shift and broadening rates of the 52S1/2 →62P1/2 and 52S1/2 →62P3/2 transitions of rubidium with He, Ar, CH4, and C2H6

    Science.gov (United States)

    Guy, M. R.; Guild, E. M.; Young, J. W.; Sheets, I. O.; Pitz, G. A.

    2016-01-01

    Pressure induced broadening and spectral shift rates have been resolved for the two ground state hyperfine lines in the 52S1/2 →62P1/2 and 52S1/2 →62P3/2 of 85Rb and 87Rb in the presence of 5-50 Torr of helium, argon, methane, and ethane. Broadening rates averaged over the hyperfine components, for the P1/2 transition for He, Ar, CH4, and C2H6 are 60.2, 45.2, 63.8, and 60.4 MHz/Torr, respectively and 50.4, 42.4, 62.0, and 60.4 MHz/Torr for the P3/2 transition. Average spectral shift rates for the P1/2 transition were found to be 15.7, -11.5, -18.1, and -19.9 MHz/Torr for He, Ar, CH4, and C2H6, respectively, and 3.1, -12.6,-21.8, and -19.9 MHz/Torr for the P3/2 transition. Deviation in broadening and shift rates between hyperfine lines was found to be as high as 16 and 7.6 MHz/Torr respectively.

  19. Time-dependent calculations of hydrogen spectral line shapes in dense plasmas

    Science.gov (United States)

    Olchawa, Wiesław

    2001-04-01

    A new formalism has been elaborated for calculations of hydrogen line profiles emitted by dense plasmas. Calculated line shapes are broadened, shifted and asymmetrical. The formalism is very general and yields full line shapes, shifts and widths at relatively small number of assumptions. For this purpose a new basis of the appropriate subspace of the Hilbert space has been built. This basis gives an accurate description of the quadratic Stark effect and the interaction of the emitter with field gradients. A computer simulation has been used to determine the emitter perturbations by electrons and ions. Final results have been compared with experimental and theoretical findings of other authors.

  20. Moessbauer meets Fano at X-ray energies: Controlled line shapes in cooperative emission from nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Heeg, Kilian P.; Ott, Christian; Pfeifer, Thomas; Evers, Joerg [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Schumacher, Daniel; Wille, Hans-Christian; Roehlsberger, Ralf [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany)

    2014-07-01

    Control of spectroscopic line shapes at hard X-ray energies is demonstrated in the reflectance of a thin film cavity with embedded Moessbauer nuclei. Tunable Fano interference between a spectrally broad cavity response and a narrow bound state nuclear contribution enables us to switch between Lorentz- and Fano-profiles. Spectroscopic signatures such as the cooperative Lamb shift and superradiant line broadening are extracted from the recorded asymmetric line shapes with high precision and agree excellently with our theoretical model. Our results advance spectroscopy and precision metrology in the hard X-ray domain, and provide access to a multitude of applications linked to Fano interference.