Rotational relaxation of OCS by spherical and nearly spherical perturbers

摘要

Collision cross sections for the transverse relaxation of OCS by spherical and nearly spherical perturbers have been measured. The observed cross sections vary linearly with bgr;=lsqb;I22/(I1+I2)2agr;22Mrsqb;1/5, whereI1andI2are the ionization energies of OCS and the perturber. agr;2is the polarizability of the perturber, andMis the reduced mass of the colliding molecules. Calculations based on the Andersonndash;Tsaondash;Curnutte theory using a simple dispersion force model for the OCSndash;perturber interaction are in qualitative agreement with the experimental results. By doubling the strength of the dispersion forces used to model the OCSndash;perturber interactions, the calculated cross sections are brought into agreement with the measured ones. The observed linear relation between the cross section and bgr; can be used to predict cross sections for other (polar molecule)ndash;(nonpolar nearly spherical perturber) collisions.