An ab initio study of the transition moments, transition probabilities, and radiative lifetimes of the quartet states of the BeN molecule

Abstract

Transition moments for the quartet states of BeN are calculated at the multi-reference single and double excitations configuration interaction level using natural orbitals as one-particle basis and an extended set of 98 contracted Cartesian Gaussians. The large shift of ≈ 1.2 a 0 in the equilibrium distance of the state B 4Σ − is mainly responsible for a continuous character of the spectrum in the UV (≈ 273 nm) corresponding to B 4Σ −-X 4Σ − transitions which are expected to be relatively intense as suggested by the magnitude of the transition moment. The A 4Π-X 4Σ − transitions are expected to occur in the near IR (λ 10 ≈ 956 nm) and to be relatively weak ( A 10 = 5.7 x 10 3 s −1) as a result of the small value of the transition moment. Radiative lifetimes for the state A 4Π are estimated to be of the order of 100 μs. For the B 4Σ −-A 4Π transition, a maximum intensity in a continuous spectrum in the near UV (≈ 330 nm) is also predicted. Since no experimental results are available, comparisons with similar transitions in C 2 +, O 2 +, and NO are also presented.