Multiquantum vibrational transitions in O2(v≥25)+O2(v=0) collisions

The quenching of highly vibrationally excited O2 in collision with O2(v=0) is investigated using a semiclassical wave packet method. We find that nonreactive collisions dominate the relaxation of O2(v) and for v in the range 25 to 30 the reactive channel makes little contribution to the quenching process, in agreement with our earlier investigation. We report vibrational transition cross sections and relaxation rate coefficients for v=25 to 30 of the excited O2(v) molecule. Our study shows that a multiquantum process involving a 2→1 vibrational transition which has not been included in previous calculations makes an important contribution to the rate coefficients for the relaxation of O2 vibrational levels v≥27.