On the quantum mechanical theory of unimolecular reactions through a narrow bottleneck: The prompt and delayed dissociation

The quantum dynamics of unimolecular dissociation are discussed for a typical situation where the number of energy rich but bound (zero order) states far exceeds the number of states with enough energy along the reaction coordinate in order to dissociate. It is shown that one can introduce a new basis of states, the ‘trapping’ states, which diagonalize the effective Hamiltonian that governs the dynamics in the bound subspace. The properties of these states are discussed with special reference to the two distinct time regimes (prompt and delayed) for the dissociation that are expected for such a congested level structure.