Influence of the finite duration and efficiency of collisions on the orientational relaxation times of non-spherical molecules in the hindered rotation limit

The present work deals with the influence of the efficiency and finite duration of intermolecular interactions on the orientational relaxation times (ORTs) in the hindered rotation limit. To this end, a single-particle non-markovian Zwanzig-type master equation is used. The most general case of asymmetric top molecules is considered and a number of analytical results is derived. A possibility is demonstrated to extract non-trivial information about the peculiarities of molecular rotation and interaction by examining variation of ORTs and ratios of ORTs of different ranks vs. the angular momentum relaxation time. The collision efficiency is proved to influence these dependencies markedly. This effect should be necessarily taken into account in describing the orientational relaxation.