Collision energy- and spin-orbit coupling-dependence of quenching probability in the electronic energy transfer reaction S( 1D)+CO→S( 3P)+CO(v,J)

Abstract

Quenching probabilities ( P Q values) in the energy transfer reaction S( 1D)+CO→S( 3P)+CO(v,J) have been calculated as functions of both center of mass collision energy ( E coll) and spin-orbit coupling ( H 12) by means of the surface-hopping trajectory method using ab initio fitted potential energy surfaces (PESs). Two ab initio fitted potential energy surfaces (singlet and triplet PESs) obtained at the MP2/6-31G* level were employed in the quenching process. The surface hopping was treated as the Landau–Zener model in the crossing seam between the singlet and triplet PESs. The calculations showed that the reaction is composed of three reaction channels: one is a complex channel in which the reaction proceeds via a long-lived complex [SCO], and the second one is a direct channel in which the reaction proceeds without the long-lived complex. The third one is a mixed channel composed of direct and complex channels. The P Q decreases with increasing E coll and increases linearly with increasing spin-coupling value H 12. The collision energy dependence of P Q is due to the fact that branching ratio of direct channels to complex ones is varied as a function of collision energy.