Excitação vibracional do SO2 em colisões com átomos de hidrogênio hipertérmicos: um estudo quase-clássico

Abstract

The purpose of this work is to report a theoretical investigation translation-to-vibration energy transfer (T-V ET) process using a quasi-classical trajectories (QCT) methodology of the collision H(2S) atoms and SO2(˜X 1A’) molecules. This study was motivated by recent experiments involving the reaction H+SO2 at translational energy of 59 kcal/mol reported by Ma et al. The obtained results reproduce the experimental evidence that during majority of inelastic non-reactive collision processes there is a metastable intermediate formation (HOSO and HSO2). Nevertheless, the analisys of the trajectories shows that there are influence of two distinct mechanisms in T-V ET process: direct and indirect. Direct or impulsive type is responsible by an immediate encounter and fast separation between the reactants but without complex formation. In turn, indirect type is one that forms short-lived complex shortly after the reactants dissociates into a vibrationally hot sulfur dioxide molecules and a kinetically slower hydrogen atoms or cold H atoms. For such study, it was necessary to use the HSO2 (2A) DMBE potential energy surface previously reported by Ballester et al.