Speed-Dependent Anisotropy Parameters in the UV Photodissociation of Ozone

Resonance-enhanced multiphoton ionization coupled with time-of-flight product imaging has been used to study the O2(Σg) + O(Pj) product channel in the UV photodissociation of ozone at photolysis wavelengths of 226, 230, 240, and 266 nm. For dissociation at 226 and 230 nm the O(P2) fragment is produced with a strongly bimodal velocity distribution, in keeping with the previous findings of Miller et al., Syage, and Stranges et al. at photolysis wavelengths of 226 and 193 nm. At the longer dissociation wavelengths of 240 and 266 nm, the bimodal velocity distribution becomes less evident in the O(P2) product. Anisotropy parameters have been determined as a function of the O(P2) fragment speed. A very similar and clear speed dependence is evident at all photolysis wavelengths considered, with the anisotropy parameters rising steadily as the oxygen atom speed increases. The UV dissociation dynamics of ozone to the channel producing triplet products are discussed in light of this analysis.