Anharmonicity effects on vibrational predissociation

We study the effect of the anharmonicity of a normal diatomic molecule BC on the vibrational predissociation rates of a van der Waals molecule X…BC, where X is a rare-gas atom. The experimentally determined nonlinear dependence of vibrational predissociation rates of the HeI₂ (B) molecule on the vibrational excitation of the Iz bond, is very well reproduced by a simple analytical model. The relevance of this model in determining potential parameters of the van der Waals interaction is discussed. Applicationto other systems are presented and the effect of the reduced mass for relative motion is examined.