Vibrational relaxation and vibrational predissociation as dynamic tunnelling processes

The dynamics of vibrational relaxation and vibrational predissociation processes, forbidden by the classical adiabatic Ehrenfest principle, are examined. A general approach to the calculation of rate constants for processes represented by total collision and half-collision models is formulated. Simple models which make it possible to understand the characteristics of the processes discussed are described and are extended to the case of real three-dimensional motion. Examples providing a fairly complete illustration of the present understanding of dynamic tunnelling processes are presented. The bibliography includes 45 references.