Rotational relaxation contributions to infrared pressure broadening in ozone

Abstract

Rotational relaxation times in ozone–ozone collisions have been measured for selected rovibrational levels using the time-resolved infrared double-resonance technique. Rotationally inelastic processes account for at least 90% of the measured pressure-broadening rate. The rotational-state dependence of the relaxation cross sections is in good accord with the collision models used in current theories of pressure broadening. The V–V energy transfer rate between symmetric and asymmetric stretching modes of ozone has also been measured; the V–V cross section is approximately 15 Å2, about an order of magnitude smaller than that for rotational energy transfer.