Mechanism of the product vibrational-rotational state selectivity in a gas phase ion-molecule collision

Abstract

The mechanism of a gas phase proton transfer reaction, , has been investigated by means of quasi-classical trajectory calculations with an ab initio fitted potential energy surface. In particular, we focused our attention on the selectivity of vibrational and rotational states of the product OH formed by the reaction. It was found that vibrational and rotational state distributions of the product OH can be deconvolved by two components originating from two different reaction channels. One is a complex formation channel in which the trajectory proceeds via a long-lived intermediate complex [OHF]. The other is a direct channel in which the trajectory proceeds without complex formation. It was concluded that collinear and near-collinear collisions lead to the direct channel, whereas side-attack collision and collision with a large impact parameter lead to the intermediate-complex channel.