COLLISIONAL EXCITATION OF CO BY S(D-1)/S(P-3) ATOMS

Vibrational and rotational distributions of CO excited by collisions with either S(D-1) atoms (average collision energy, [E(coll)] = 4 kcal/mol) or S(P-3) atoms ([E(coll)] = 10 kcal/mol) have been studied by monitoring the products using vacuum ultraviolet laser induced fluorescence. Ab initio potential energy surfaces (PESs) of (1)A' and (3)A' states of OCS have been calculated. Quasiclassical trajectory (QCT) calculations using LEPS-PESs fitted to the ab initio PESs were performed. For the S(D-1) + CO system, the intermediate complex channel model in which the collision proceeds via the (1)A' state intermediate complex predicts the formation of the vibrationally excited CO(v=0,1,2). On the other hand, the direct channel model in which the collision directly proceeds without the intermediate step predicts the formation of vibrationless state CO. The experimental vibrational and rotational distributions agree with the QCT results for the intermediate complex channel model of the S(D-1) + CO system.