Characterization of low-lying electronic states of diatomic sodium bismuthide cation including the spin-orbit coupling effect

Abstract

We present a high-level ab initio investigation of the diatomic sodium bismuth (NaBi+), which is a hitherto experimentally unknown species. The explicitly correlated multireference configuration interaction method is used to calculate energy points of thirteen low-lying Λ-S electron states associated with five dissociation limits. Detailed information on structural features, electronic characters, and spectroscopic constants is acquired. Our calculated relative energies between each of the interested higher dissociation limits and the lowest one for NaBi+, as well as splittings of energy levels for Bi, agree well with experimental data. Besides, we have identified and discussed the transition properties of bands from excited Ω states to the ground one, including transition dipole moments, Einstein coefficients, Franck-Condon factors, vibrational branching ratios, and radiative lifetimes. The extent of perturbations originating from the spin-orbit coupling effect to the present species is quantified through discussions on term values of spin-orbit matrix elements, and the spin-orbit coupling effect is proved to have introduced a significant effect to the low-lying electronic states of NaBi+.