Photofragmentation of OClO Clusters in a Supersonic Jet at 360 and 275 nm

Abstract

Using photofragment translational energy spectroscopy, we studied the photochemical decay of chlorine dioxide (OClO) clusters in a cold beam with Ne as carrier gas. The products ClO, OClO, Cl2O3, and Cl2O4 generated by 360 nm excitation wereexcept for the fast ClO fragments which arise from monomer photodissociationfound to be slow moving and with broad time-of-flight distributions. They show an approximately thermal translational energy distribution of 300−500 K and a recoil anisotropy β ≈ 0, as measured for the representative OClO product. Furthermore with excitation at 275 nm where the OClO monomer has no absorption, the same slow moving product species were created, indicating that they are evaporation products of excited cluster species. A reaction scheme is proposed which includes unimolecular photochemical decays and bimolecular cage reactions of initially formed fragments among themselves and with cluster constituents.