The role of short range interaction in molecular collision broadening

The effect of a short range interaction on collision broadening is investigated for molecular transitions. Expressions for the collision width are derived for an intermolecular potential consisting of a multipole term together with a core potential of the form r−n. Impact and straight classical path approximations are used. The short range interaction is included to all orders, but contributions up to second order are retained for the multipole interaction. This approach eliminates the need for a cutoff at small impact parameters. Our results represent the proper generalizations, which reduce to the results of the Anderson theory, in the limit as n → ∞. This work suggests that some information about the effective core potential can be obtained from a comparison of the theory and the experiment.