Molecular Collisions. X. Restrictedhyphen;Distortedhyphen;Wavendash;Born and Firsthyphen;Order Sudden Approximations for Rotational Excitation of Diatomic Molecules

摘要

Although a number of approximation methods have been widely used in the field of molecular rotational excitation and scattering, their interrelationships and ranges of applicability have not always been clearly established. The present work is a comparison of several of these approximations. Considered are the timehyphen;independent treatments such as the distorted wave approximation (DWA), the restricted distorted wave (RDW) and the RDWndash;Born approximations, and the timehyphen;dependent ones such as the sudden approximation (SA), full trajectory and straighthyphen;line limit, and the firsthyphen;order perturbation approximations. Equivalence is demonstrated between the RDWndash;Born and firsthyphen;order SA, and convenient analytical forms are presented for the resulting transition probabilities.