Vibrational Relaxation in Liquids

The binary collision model of vibrational relaxation in liquids is examined within the framework of statistical mechanics. The results apply to diatomic molecules with large vibrational spacings when very dilute in an effective thermal reservoir of structureless particles. It is demonstrated that a simple binary collision theory can be derived only if rather strong assumptions are made about the nature of the molecules. Even then, the theory which emerges differs significantly from those proposed by earlier workers.