Spontaneous predissociation in BrCl: A possible role for shape resonances in threshold predissociation

A computational study of the spontaneous predissociation of the B 0+ (3 Π) state of BrCl indicates that this process is due to rotation–electronic coupling with a weakly bound state which intersects the B potential curve on its attractive branch near the first molecular dissociation limit. The state responsible for the predissociation is very likely the 1 Π state, the analog of the states responsible for this same process in I2 and Br2 . The sharp onset of predissociation is a threshold phenomenon and leads to a revised estimate of the ground state dissociation energy 𝒟e=18 244(5) cm−1. Broad shape resonances associated with the centrifugal barrier in the predissociative state can yield marked enhancement of the predissociative decay in favorable circumstances.