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

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 Lande g-factors, are newly given. The results presented here question the existence of the FS level 4d(2)5s5p (1)G(4) 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 Nb-93 II with a good accuracy and are confirmed by ab initio calculations. For instance, the most influential parameters a(5s)(10) and a(4d)(01) are, respectively, equal to 393.4 (3.2) and 16.06 (0.19) mK for the 4d(2)5s(1)5p(1) configuration.