Rotational and spin-orbit effects in the dynamics of O(3Pj)+hydrocarbon reactions. II. Models for spin-orbit propensities

Abstract

The spin-orbit states of OH have been found in part I to be unequally populated in reactions of O(3Pj) with saturated hydrocarbons. We clarify the correlations in these systems within an adiabatic, Ω-conserving approximation, and show that the observed OH spin-orbit distributions are not well reproduced in this adiabatic limit. However, the inclusion of strong nonadiabatic coupling between surfaces of the same Ω and parity results in a much improved prediction. The necessary mixing is demonstrated to be compatible with a previous independent characterization of the entrance channel surfaces in O(3Pj) + CH4 collisions, and with the known propensities for inelastic, j-changing collisions of O(3Pj) with closed shell partners. The nonadiabatic model which agrees best with the observed OH spin-orbit ratios suggests that the O(3Pj) reactivity should vary only moderately with j.