Free access article

A&A 399, 343-349 (2003)
DOI: 10.1051/0004-6361:20021797

Radiative lifetime and oscillator strength determinations in Sm III

E. Biémont^{1, 2}, H. P. Garnir¹, U. Litzén³, K. Nielsen³, P. Quinet^{1, 2}, S. Svanberg⁴, G. M. Wahlgren³ and Z. G. Zhang<sup>4

1</sup>  Astrophysique et Spectroscopie, Université de Mons-Hainaut, 7000 Mons, Belgium
²  IPNAS (Bât. B15), Université de Liège, Sart Tilman, 4000 Liège, Belgium
³  Lund Observatory, Box 43, Lund University, 221 00 Lund, Sweden
⁴  Department of Physics, Lund Institute of Technology, PO Box 118, 221 00 Lund, Sweden

(Received 25 October 2002 / Accepted 22 November 2002)

Abstract
Radiative lifetimes of 6 levels belonging to the 4f ⁵( ⁶H , ⁶F )5d configuration of Sm III have been measured for the first time using a time-resolved laser-induced fluorescence technique. Experimental data have been compared with semi-empirical calculations. The agreement is excellent for 4 levels with ⁶F as a parent term. Larger discrepancies (53 and 37%) are observed for 2 levels with ⁶H and ⁶F , respectively, as a parent term and are explainable by strong mixing and cancellation effects occurring in the line strength calculations which are responsible of "instabilities" occurring in the lifetimes considered as a function of J value within the term. Branching ratios for the lines depopulating the levels of interest have been measured by Fourier transform spectroscopy. A first set of oscillator strengths has been deduced for this ion.

Key words: atomic processes -- atomic data -- stars: chemically peculiar

Offprint request: E. Biémont, E.Biemont@ulg.ac.be
or P. Quinet, quinet@umh.ac.be

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