State-selected vibrational relaxation rates for highly vibrationally excited oxygen molecules

Abstract

The state‐selected vibrational relaxation rates in O2+O2 collisions, with one O2 molecule in a highly vibrationally excited state, have been calculated from first principles. The vibrationally close‐coupled, rotationally infinite order sudden approximation has been used to treat the collision dynamics and a potential energy surface based on high quality ab initio calculations, which include the variation of the O2 vibrational coordinates, has been developed. The calculated relaxation rates are in good agreement with those obtained from experiment for 8≤v<26 but fail to reproduce the sharp increase observed experimentally for v≥26 indicating the onset of a new vibrational relaxation mechanism.