The Experts below are selected from a list of 171 Experts worldwide ranked by ideXlab platform
J Dembczynski - One of the best experts on this subject based on the ideXlab platform.
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semi empirical analysis of Oscillator Strengths for nb ii
Journal of Quantitative Spectroscopy & Radiative Transfer, 2015Co-Authors: J Ruczkowski, S Bouazza, M Elantkowska, J DembczynskiAbstract:Abstract Semi-empirical wave functions, proven via comparison of the expected and experimental hyperfine structure constants and gJ-factors in previous papers, were used for the parametrization of the Oscillator Strengths for electric-dipole transitions in Nb II, where reliable experimental data were available. The angular coefficients of the transition matrix in pure SL coupling were found from straightforward Racah algebra. The transition matrix was transformed into the actual intermediate coupling by the fine structure wave functions. The transition integrals were treated as free parameters in the least squares fit to experimental gf values. This procedure allowed us to obtain the values of transition integrals and predict the values of Oscillator Strengths for transitions from odd levels in a wide spectral range.
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semi empirical calculations of Oscillator Strengths and hyperfine constants for ti ii
Journal of Quantitative Spectroscopy & Radiative Transfer, 2014Co-Authors: J Ruczkowski, M Elantkowska, J DembczynskiAbstract:Abstract As the result of our studies on the atomic structure of complex atoms we produced high quality wave functions for both the even and odd systems of configurations. The quality of wave functions was proved via comparison of the expected and experimental hyperfine structure constants and g J -factors. These wave functions were used for the parametrization of the Oscillator Strengths for electromagnetic transitions in Ti II, where reliable experimental data were available. The least squares fit to experimental values for some transitions, published in the NIST Atomic Spectra Database, allowed us to obtain the values of transition integrals and parametrize the Oscillator Strengths.
T. A. A. Sigut - One of the best experts on this subject based on the ideXlab platform.
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Astrophysical determination of optical Oscillator Strengths for Ti II
Monthly Notices of the Royal Astronomical Society, 1994Co-Authors: Tanya Ryabchikova, G. M. Hill, John D. Landstreet, N. Piskunov, T. A. A. SigutAbstract:An internally consistent set of relative Oscillator Strengths for 109 spectral lines of Ti II in the range 3800-5500 A has been derived. These Oscillator Strengths have been obtained by combining available laboratory data and theoretical calculations with new astrophysical Oscillator Strengths determined from both published photographic equivalent width lists and spectral synthesis of a number of available Reticon spectra of several sharp-lined stars. The accuracy of our astrophysical Oscillator Strengths has been tested by determining astrophysical gf-values for a number of lines of Fe II by the same methods
Hans Lundberg - One of the best experts on this subject based on the ideXlab platform.
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experimentally measured radiative lifetimes and Oscillator Strengths in neutral vanadium
Astrophysical Journal Supplement Series, 2016Co-Authors: Charlotte Holmes, Juliet C. Pickering, Hans Lundberg, M P Ruffoni, Richard Blackwellwhitehead, Hampus Nilsson, L Engstrom, Henrik Hartman, M T BelmonteAbstract:We report a new study of the V i atom using a combination of time-resolved laser-induced fluorescence and Fourier transform spectroscopy that contains newly measured radiative lifetimes for 25 levels between 24,648 cm-1 and 37,518 cm-1 and Oscillator Strengths for 208 lines between 3040 and 20000 from 39 upper energy levels. Thirteen of these Oscillator Strengths have not been reported previously. This work was conducted independently of the recent studies of neutral vanadium lifetimes and Oscillator Strengths carried out by Den Hartog et al. and Lawler et al., and thus serves as a means to verify those measurements. Where our data overlap with their data, we generally find extremely good agreement in both level lifetimes and Oscillator Strengths. However, we also find evidence that Lawler et al. have systematically underestimated Oscillator Strengths for lines in the region of 9000 ± 100. We suggest a correction of 0.18 ± 0.03 dex for these values to bring them into agreement with our results and those of Whaling et al. We also report new measurements of hyperfine structure splitting factors for three odd levels of V i lying between 24,700 and 28,400 cm-1.
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Oscillator Strengths for lines of astrophysical interest in Rh II
Astronomy & Astrophysics, 2012Co-Authors: Pascal Quinet, Emile Biémont, Hans Lundberg, Henrik Hartman, Patrick Palmeri, Lars Engström, Hampus NilssonAbstract:Aims. This work reports Oscillator Strengths for transitions of astrophysical interest in singly ionized rhodium. Methods. Seventeen radiative lifetimes in Rh + have been measured with the time-resolved laser-induced fluorescence technique and combined with theoretical branching fractions calculated using a relativistic Hartree-Fock model including core-polarization effects to obtain Oscillator Strengths. Results. On the basis of the good agreement between theory and experiment for the lifetimes, new reliable Oscillator Strengths have been deduced for a set of 113 Rh II transitions in the spectral range 153–418 nm.
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Experimental Oscillator Strengths for the spectrum of neutral manganese
Monthly Notices of the Royal Astronomical Society, 2005Co-Authors: Richard Blackwell-whitehead, Juliet C. Pickering, Gillian Nave, Hans LundbergAbstract:We report laboratory measurements of Oscillator Strengths for 44 transitions in the Mn T spectrum covering the wavelength range 209-2780 nm. Nine energy level lifetimes have been measured using time resolved laser-induced fluorescence (LIF). The lifetimes have been combined with branching fractions measured by Fourier transform spectroscopy to obtain absolute Oscillator Strengths. In total, 24 of these Oscillator Strengths are measured for the first time, including transitions in the previously unobserved infrared region above 2.0 mu m.
M. Taser - One of the best experts on this subject based on the ideXlab platform.
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Oscillator Strengths of allowed transitions for O III
Atomic Data and Nuclear Data Tables, 2012Co-Authors: Şule Ateş, G. Tekeli, Gültekin Çelik, M. TaserAbstract:Abstract The electric dipole Oscillator Strengths for lines in O III between some singlet and triplet levels have been calculated using the weakest bound electron potential model theory and the quantum defect orbital theory. In the calculations, both multiplet and fine-structure transitions are studied. The calculated Oscillator Strengths have been compared with available theoretical and experimental results. Good agreement with results in the literature has been obtained.
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Oscillator Strengths for Be I
Atomic Data and Nuclear Data Tables, 2012Co-Authors: Şule Ateş, Gültekin Çelik, Selma Özarslan, M. TaserAbstract:Abstract The electric dipole Oscillator Strengths for lines between some singlet and triplet levels have been calculated using the weakest bound electron potential model theory and the quantum defect orbital theory for Be I. In the calculations both multiplet and fine structure transitions are studied. We employed both the numerical Coulomb approximation method and numerical non-relativistic Hartree–Fock wavefunctions for expectation values of radii. The necessary energy values have been taken from experimental energy data in the literature. The calculated Oscillator Strengths have been compared with available theoretical results. A good agreement with the results in the literature has been obtained.
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Oscillator Strengths for singly ionized oxygen
The European Physical Journal D, 2009Co-Authors: Şule Ateş, G. Tekeli, Gültekin Çelik, Erhan Akin, M. TaserAbstract:The electric dipole Oscillator Strengths for multiplet and individual lines between some doublet and quartet levels have been calculated using the weakest bound electron potential model theory (WBEPMT) in singly ionized oxygen. We employed both numerical Coulomb approximation (NCA) wave functions and numerical non-relativistic Hartree-Fock (NRHF) wave functions for expectation values of radii in determination of parameters. The calculated Oscillator Strengths have been compared with available theoretical and experimental results. A good agreement with results in literature has been obtained. Moreover, Oscillator Strengths not existing in the literature for some highly excited levels have been obtained using this method.
Hampus Nilsson - One of the best experts on this subject based on the ideXlab platform.
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experimental and theoretical Oscillator Strengths of mg i for accurate abundance analysis
Astronomy and Astrophysics, 2017Co-Authors: Asli Pehlivan Rhodin, Hampus Nilsson, Henrik Hartman, Per JonssonAbstract:Context. With the aid of stellar abundance analysis, it is possible to study the galactic formation and evolution. Magnesium is an important element to trace the α-element evolution in our Galaxy. For chemical abundance analysis, such as magnesium abundance, accurate and complete atomic data are essential. Inaccurate atomic data lead to uncertain abundances and prevent discrimination between different evolution models. Aims: We study the spectrum of neutral magnesium from laboratory measurements and theoretical calculations. Our aim is to improve the Oscillator Strengths (f-values) of Mg i lines and to create a complete set of accurate atomic data, particularly for the near-IR region. Methods: We derived Oscillator Strengths by combining the experimental branching fractions with radiative lifetimes reported in the literature and computed in this work. A hollow cathode discharge lamp was used to produce free atoms in the plasma and a Fourier transform spectrometer recorded the intensity-calibrated high-resolution spectra. In addition, we performed theoretical calculations using the multiconfiguration Hartree-Fock program ATSP2K. Results: This project provides a set of experimental and theoretical Oscillator Strengths. We derived 34 experimental Oscillator Strengths. Except from the Mg i optical triplet lines (3p 3P°0,1,2-4s 3S1), these Oscillator Strengths are measured for the first time. The theoretical Oscillator Strengths are in very good agreement with the experimental data and complement the missing transitions of the experimental data up to n = 7 from even and odd parity terms. We present an evaluated set of Oscillator Strengths, gf, with uncertainties as small as 5%. The new values of the Mg i optical triplet line (3p 3P°0,1,2-4s 3S1) Oscillator strength values are 0.08 dex larger than the previous measurements.
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experimentally measured radiative lifetimes and Oscillator Strengths in neutral vanadium
Astrophysical Journal Supplement Series, 2016Co-Authors: Charlotte Holmes, Juliet C. Pickering, Hans Lundberg, M P Ruffoni, Richard Blackwellwhitehead, Hampus Nilsson, L Engstrom, Henrik Hartman, M T BelmonteAbstract:We report a new study of the V i atom using a combination of time-resolved laser-induced fluorescence and Fourier transform spectroscopy that contains newly measured radiative lifetimes for 25 levels between 24,648 cm-1 and 37,518 cm-1 and Oscillator Strengths for 208 lines between 3040 and 20000 from 39 upper energy levels. Thirteen of these Oscillator Strengths have not been reported previously. This work was conducted independently of the recent studies of neutral vanadium lifetimes and Oscillator Strengths carried out by Den Hartog et al. and Lawler et al., and thus serves as a means to verify those measurements. Where our data overlap with their data, we generally find extremely good agreement in both level lifetimes and Oscillator Strengths. However, we also find evidence that Lawler et al. have systematically underestimated Oscillator Strengths for lines in the region of 9000 ± 100. We suggest a correction of 0.18 ± 0.03 dex for these values to bring them into agreement with our results and those of Whaling et al. We also report new measurements of hyperfine structure splitting factors for three odd levels of V i lying between 24,700 and 28,400 cm-1.
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Oscillator Strengths for lines of astrophysical interest in Rh II
Astronomy & Astrophysics, 2012Co-Authors: Pascal Quinet, Emile Biémont, Hans Lundberg, Henrik Hartman, Patrick Palmeri, Lars Engström, Hampus NilssonAbstract:Aims. This work reports Oscillator Strengths for transitions of astrophysical interest in singly ionized rhodium. Methods. Seventeen radiative lifetimes in Rh + have been measured with the time-resolved laser-induced fluorescence technique and combined with theoretical branching fractions calculated using a relativistic Hartree-Fock model including core-polarization effects to obtain Oscillator Strengths. Results. On the basis of the good agreement between theory and experiment for the lifetimes, new reliable Oscillator Strengths have been deduced for a set of 113 Rh II transitions in the spectral range 153–418 nm.