| 1. |
- Biemont, E., et al.
(författare)
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Lifetime measurements and calculations in Y+ and Y2+ ions
- 2011
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Ingår i: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 1365-2966 .- 0035-8711. ; 414:4, s. 3350-3359
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Tidskriftsartikel (refereegranskat)abstract
- We report a new set oftheoretical transition probabilities in Y II, obtained using a multiconfiguration relativistic Hartree-Fock method including core polarization. The overall quality of the calculations is assessed by comparisons with new and previous lifetime measurements. In this paper, we report new measurements of five lifetimes in the 4d5p and 5s5p configurations, in the energy range of 32 048-44 569 cm(-1), obtained by the time-resolved laser-induced fluorescence method. A similar theoretical model, applied to Y III, leads to results in good agreement with new laser measurements of two 5p levels obtained in this work and with previous beam-foil results for 5d and 6s levels. An extensive set of oscillator strengths is also proposed for Y III.
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| 2. |
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| 3. |
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| 4. |
- Malcheva, G., et al.
(författare)
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Radiative parameters of Nb i excited states
- 2011
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Ingår i: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 1365-2966 .- 0035-8711. ; 412:3, s. 1823-1827
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Tidskriftsartikel (refereegranskat)abstract
- Radiative lifetimes of 17 excited levels of Nb i, in the energy range 27 400-47 700 cm-1 (5p y 6D degrees(9/2), 5p x 6D degrees(7/2), 5p w 4G degrees(7/2,9/2,11/2), 5s5p v 4D degrees(1/2,3/2,5/2,7/2), 5s6p n 4D degrees(1/2,3/2,5/2,7/2), 5s6p o 4F degrees(3/2,5/2,7/2,9/2)), have been measured. For 15 of these levels, the lifetimes are obtained for the first time. The lifetimes were measured using the time-resolved laser-induced fluorescence technique and the experiments are complemented by a theoretical investigation using a relativistic Hartree-Fock method including core polarization. By combining the experimental lifetimes and the calculated branching fractions, we obtain transition probabilities for the individual de-excitation channels from the investigated levels.
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| 5. |
- Nilsson, Hampus, et al.
(författare)
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Transition probabilities of astrophysical interest in the niobium ions Nb+ and Nb2
- 2010
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Ingår i: Astronomy & Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 511
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Tidskriftsartikel (refereegranskat)abstract
- Aims. We attempt to derive accurate transition probabilities for astrophysically interesting spectral lines of Nb II and Nb III and determine the niobium abundance in the Sun and metal-poor stars rich in neutron-capture elements. Methods. We used the time-resolved laser-induced fluorescence technique to measure radiative lifetimes in Nb II. Branching fractions were measured from spectra recorded using Fourier transform spectroscopy. The radiative lifetimes and the branching fractions were combined yielding transition probabilities. In addition, we calculated lifetimes and transition probablities in Nb II and Nb III using a relativistic Hartree-Fock method that includes core polarization. Abundances of the sun and five metal-poor stars were derived using synthetic spectra calculated with the MOOG code, including hyperfine broadening of the lines. Results. We present laboratory measurements of 17 radiative lifetimes in Nb II. By combining these lifetimes with branching fractions for lines depopulating the levels, we derive the transition probabilities of 107 Nb II lines from 4d(3)5p configuration in the wavelength region 2240-4700 angstrom. For the first time, we present theoretical transition probabilities of 76 Nb III transitions with wavelengths in the range 1430-3140 angstrom. The derived solar photospheric niobium abundance log epsilon(circle dot) = 1.44 +/- 0.06 is in agreement with the meteoritic value. The stellar Nb/Eu abundance ratio determined for five metal-poor stars confirms that the r-process is a dominant production method for the n-capture elements in these stars.
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| 6. |
- Quinet, P., et al.
(författare)
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Atomic data for VUV lines of astrophysical interest in singly ionized rhodium
- 2011
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 184:3-6, s. 174-176
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Tidskriftsartikel (refereegranskat)abstract
- The first theoretical transition probabilities and oscillator strengths are reported for Rh II lines of astrophysical interest in the VUV region (100-200 nm). They have been obtained through the use of a pseudo-relativistic Hartree-Fock model including core-polarization effects and the accuracy has been estimated to be about 10-15% through a comparison with new experimental lifetimes measured using the time-resolved laser-induced fluorescence technique. (C) 2010 Elsevier B.V. All rights reserved.
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| 7. |
- Quinet, P., et al.
(författare)
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Oscillator strengths for lines of astrophysical interest in Rh II
- 2012
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Ingår i: Astronomy & Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 537
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Tidskriftsartikel (refereegranskat)abstract
- 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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| 8. |
- Quinet, P., et al.
(författare)
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Oscillator strengths for lines of astrophysical interest in Rh II
- 2012
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 537, s. A74-A74
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Tidskriftsartikel (refereegranskat)abstract
- 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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