The Theory of Collisions between Two Diatomic Molecules

The general features of the elastic and the inelastic collisions have been investigated in this paper. The inelastic collisions are confined to the rotational and the vibrational ones, and the electronic degrees of freedom are disregarded throughout. Starting from the fundamental set of equations for the collision problem, the effects of the non-spherical character of the intermolecular potential are discussed. For the ~otational transitions where the level spacings are rather small, the semi-classical method is employed and 'for the vibrational transitions, the distorted wave method is developed and some simple methods to estimate the cross sections are,also discussed. Special considerations are also given for the cases in which the two colliding molecules are identical