Vibrational Energy Transfer Processes in Collisions between Diatomic Molecules

Vibrationally inelastic collisions between two diatomic molecules are discussed. The system is represented by two harmonic oscillators, not necessarily identical, coupled by a time-dependent interaction potential. The time-dependent Schrödinger equation for this system is solved by obtaining the time-evolution operator, and expressions for vibrational-vibrational-translational energy transfer probabilities between any initial and final state are obtained. Numerical examples are presented which indicate among other things that multiquantum transitions can be important in vibrational-vibrational energy transfer between vibrationally excited molecules.