Radiative lifetime measurements and oscillator strengths of astrophysical interest in Ho III

Abstract

Abstract. Radiative lifetimes of three long-lived levels belonging to the 4f 10 5d configuration of Ho III have been measured, for the first time, using the time-resolved laser-induced fluorescence technique. A good agreement between the experimental lifetimes and theoretical results obtained within a multiconfigurational pseudo-relativistic Hartree-Fock (HFR) approach including core-polarization (CP) effects is observed provided an adequate scaling factor is applied to the <4f|r|5d> transition matrix element. From the comparison theory-experiment, it has been possible to assess the reliability of the oscillator strengths of the 4f-5d transitions of astrophysical interest, particularly for the lines depopulating the levels considered in the present work. The present results fill in a gap concerning the f -values of doubly ionized holmium and are needed for a quantitative evaluation of the holmium abundance in some peculiar stars.

Transition probabilities in Gd III

“…The situation has now changed and there has been, in recent years, a revival of interest for the doubly ionized species of the lanthanides. In particular, we have started a systematic investigation of the line intensities in these spectra Send offprint requests to: E. Biémont or P. Quinet e-mail: E.Biemont@ulg.ac.be or quinet@umh.ac.be within the framework of the DREAM project (for more details, see http://www.umh.ac.be/∼astro/dream.shtml) and extensive tables of transition probabilities, tested in many cases by comparison with laser lifetime measurements, have been obtained for most of the doubly ionized elements of the group (Biémont et al 1999(Biémont et al , 2001a(Biémont et al ,b,c,d, 2002Fedchak et al 2000;Li et al 2001;Palmeri et al 2000;Zhang et al 2001aZhang et al , 2002a. The case of Gd III has not been considered so far and, for this reason, the first results are presented in the present paper.…”

Radiative lifetime, oscillator strength and Landé factor calculations in doubly ionized europium (Eu iii)

“…In addition, it has been shown in many recent papers that core‐polarization of the ionic core play a very important role in the calculations of oscillator strengths for lowly ionized heavy elements and, in particular, for the third spectra of rare‐earths (see e.g. Biémont et al 1999, 2001a,b,c,d, 2002; Li et al 2001; Zhang et al 2001b, 2002a,b,c). In the present work, these effects were considered in two different ways, i.e.…”

“…This is not unforeseen because these effects are expected and have been shown to be of major importance in the theoretical investigations of lowly ionized rare‐earths (see e.g. Biémont et al 1998, 1999, 2001a,b,c,d, 2002; Quinet et al 1999; Li et al 2001; Wyart et al 2001; Zhang et al 2001a,b,c, 2002a,b,c).…”

Time-resolved laser-induced fluorescence lifetime measurements and theoretical transition probabilities in Tb III

“…The experimental arrangements used in the experiments have been described elsewhere ͑see, e.g., [10][11][12]15,16,[18][19][20] ions were obtained by laser ablation. Laser pulses, characterized by a 532 nm wavelength, a 10 Hz repetition rate, and a 10 ns duration, were emitted from a neodymium-doped yttrium aluminum garnet ͑Nd:YAG͒ laser ͑Continuum Surelite͒.…”