The second spectrum of niobium: I. Accurate fine structure study of even-parity levels

Abstract

For the first time, a parametric analysis of the fine and hyperfine structure for even-parity levels of Nb II, involving 17 configurations, has been performed. The interpretation has been carried out based on a linked-parameter method of level-fitting calculations in a large multiconfiguration basis. The sets of fine structure parameters, the leading eigenvector percentages of levels, as well as their calculated magnetic Landé g-factors are newly given. Furthermore, we confirm on the whole the validity of the attributions to term designations, previously proposed. The single-electron hyperfine structure parameters are determined in their entirety for 93 Nb II for the model space (4d + 5s) 4 with a good accuracy and confirmed by ab initio calculations. Finally, a complete list of the predicted magnetic hyperfine structure constants A of all levels of this model space was generated.

The second spectrum of niobium: II. Accurate fine structure study of odd-parity levels

“…Our computed HFS data confirm totally, as in the case of even-parity levels [24], the experimental data of Nilson and Ivarson [17], even those given this time with the biggest relative uncertainty, i.e. 4%, and also those of Young et al [16] and Cheal et al [18], which are very accurate.…”

“…Moreover, we have pointed out in a previous work [6] that for many elements the ratio F K , between F=a 10 ns (n − 1) d 2 nsnp exp /a 10 ns (n − 1) d 3 ns exp and K = a 10 ns (n − 1) d 2 nsnp cal /a 10 ns (n − 1) d 3 ns cal , is the same within uncertainties and is equal to 1.169 (average value). Assuming that polarizing effects remain the same whatever the number of p-electrons [19,25,26] and using a 10 5s 4d 3 5s 1 exp = 272.06 mK [24], one obtains by the simple rule of three: Finally, one can see good agreement between fitted HFS one-electron radial parameters and the calculated ones, gathered in table 4 for d-electrons, p-electrons and even for s-electrons, reinforcing once more the reliability of the model used for fitting.…”

Fine Structure Analysis of the Configuration System of V II. Part I: Even-Parity Levels

“…We confirm on the whole the attributions to term designations given previously [1]- [3] We propose to invert these two triplet positions as we did in Table 1. It has been brought immediately to our attention by experimental hfs data given in for the 3d 3 4s configuration obtained thanks to the fs study and ab initio calculations, as we did previously [4]- [8]. In Table 4 we give up to 100,000 cm −1 our predicted data for missing experimental energies for these five configurations, analysed in [1]- [3].…”

“…The interactions between particular states are determined quantitatively by this analysis. The complete details of fs analysis were already given in our previous papers: see for instance [8].…”

“…Up to now, no parametric analysis of hfs exists for any even or odd configurations of V II. We propose to fill this absence, as we did previously for many singly ionized atoms: Hf II, Zr II, Ta II, Ti II and Nb II [4]- [8] in an aim to complete previous works and to eliminate erroneous level assignments. The background and motivation of this work should present high interest for astrophysical investigations, very useful in the study of the history of nucleosynthesis, chemically peculiar stars and the sun.…”