Ka-mixing in the unimolecular dissociation of NO2 studied by classical dynamics calculations

Coriolis and centrifugal vibration–rotation coupling in the unimolecular dissociation of ground electronic state NO2 has been examined by using classical trajectories. The time evolution of the projection Ka of the rotational angular momentum N in a body-fixed frame is analyzed. The main result is a relation between the decomposition lifetime and the degree of Ka-mixing. For example, less than 30% of the available Ka space becomes populated for an average lifetime of 5 ps. This is consistent with the conclusions, based on time-resolved experiments, that rotation–vibration transfer is slower than reaction except just above the threshold.