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

Abstract

A parametric analysis of the fine structure (FS) and hyperfine structure (HFS) of odd-parity levels of Nb II, involving 11 configurations, has been performed in this work for the first time. The interpretation has been performed based on refined multiconfigurational FS calculations, including the main Rydberg series configurations mutually interacting. The sets of FS parameters, the leading eigenvector percentages of levels, as well as their calculated Landé g-factors, are newly given. The results presented here question the existence of the FS level 4d25s5p 1G4 at an energy of 79 171.731 cm−1 previously reported in the literature. The single-electron HFS parameters are determined in their entirety for the lowest configurations of 93Nb II with a good accuracy and are confirmed by ab initio calculations. For instance, the most influential parameters a5s10 and a4d01 are, respectively, equal to 393.4 (3.2) and 16.06 (0.19) mK for the 4d25s15p1 configuration.

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

“…Previously, it was found [9], even more so for p-electrons, that weighting the parameters k nl a κ by a ratio of spin-orbit constants obtained thanks to fine structure study and ab initio calculations, i.e. to multiply the second member of Equation (1) by: ζ nl (fs)/ζ nl (ab initio) improves the agreement of the calculated HFS values to the experimental values.…”

“…Recently we carried out fs studies of some singly ionised atoms, e.g. Ta II [8] or Nb II [9], in an effort to complete previous works and to eliminate erroneous level assignments. This time we propose a similar work concerning V II, which presents high interest for astrophysical investigations since it is very useful in the study of the history of nucleosynthesis, chemically peculiar stars and the sun.…”

Fine, hyperfine and Zeeman structures of levels of 123Sb I

“…Furthermore the accuracy of the amplitude of the energy level eigenvector is known to have particularly a strong influence on the determination of the effective mono-electronic hyperfine structure parameters deduced from magnetic dipole A and electric quadrupole B constants, experimentally obtained. For these reasons we propose to extend previous fs studies, using a method successfully tested for atoms: Si I [31], Hf I [32], Zr I [33], and ions: Nb II [34] Ta II [35], V II [36]. This method should find particular application for systems composed of many Rydberg configurations mutually interacting.…”

“…The last but not the least work was done by Hassini et al [8] who reported 138 levels derived from 617 spectral lines in the range 2536 to 24 786 cm −1 . The method applied here for fine and hyperfine structure studies was successfully used previously as regards neutral and singly ionized atoms: Zr I, Hf I, Nb II, Ta II, V II, Ti II [34][35][36]44,45], gathering the set of their studied configurations in model space when it was possible. In the fs calculations we took into account the basis setup consisted of the 7 interacting configurations: 5s 2 5p 2 6s, The spin-orbit integrals ξ nd and ξ 5p effect the interactions with distant configurations.…”

The second spectrum of niobium: III. Evaluation of line isotope shifts

“…We have now at our disposal the specific-mass and field shift values of numerous configurations of Nb II; furthermore,we have determined previously the eigenvectors of all relevant configuration levels [9,10] of this ion. So we can complete this work by evaluating the line isotope shift resorting to the sharing rule:…”