Relativistic configuration interaction calculations of the potential curves and radiative lifetimes of the low-lying states of bismuth nitride

Abstract

Relativistic effective core potentials are employed in the framework of an ab initio configuration interaction treatment including the spin–orbit interaction. A large number of strongly bound electronic states are found with T e values below 30000 cm −1 and their spectroscopic constants and transition probabilities have been computed. Special emphasis is placed on describing excited states which undergo allowed transitions to the as yet undetected a 20 − state, which is the second excited state in this molecule's spectrum. Large spin–orbit effects are noted throughout the calculations, resulting in a complicated series of avoided crossings between the various Ω states. The b 10 +, b 21 and b 32 states are shown to be dominated by the 5Σ + Λ−S state at large r values, but to have quite distinctive compositions at shorter distances because of the varying importance of the 3Π and 3Δ species in each of them, thereby producing notably different appearances for their respective potential curves in this region. The computed radiative lifetimes of all the low-lying BiN states are relatively long, never shorter than 10 μs, which is seen as reflecting the fact that at the dissociation limit all the corresponding atomic transitions are strongly forbidden by the electric-dipole selection rules.