Product vibrational distributions in CH3Br photodissociation

We performed a theoretical study of the photodissociation dynamics of CH3Br in the A ∼ band using a wavepacket propagation technique on coupled ab initio potential energy surfaces corresponding to the 3Q1 and 1Q1 states correlated at large distance with the Br ground spin–orbit state, as well as the 3Q0 and 4E states correlated to the excited one. The methyl umbrella vibrational product state distributions are found in very good agreement with experimental results. They are hotter for Br than for Br∗, and this is related to the shapes of the 3Q0 and 1Q1 potentials.