The energy distribution, angular distribution, and alignment of the O(1D2) fragment from the photodissociation of ozone between 235 and 305 nm

Abstract

Resonance-enhanced multiphoton ionization and time-of-flight product imaging have been used to study the O3(X̃ 1A1)+hν→O(1D2)+O2(1Δg) channel of the UV photodissociation of ozone at 235, 245, 255, 265, 275, 285, 298, and 305 nm. At all wavelengths, the vibrational populations, the spatial anisotropy parameter β, and the O(1D2)|mj| populations were determined. The corresponding vibrational populations of O2(1Δg) were peaked at v=0. The spatial anisotropy parameter was determined for each vibrational level and changed monotonically from about 1.2 at 235 nm to 1.7 at 298 nm. At all wavelengths, |mj| populations were peaked at |mj|=0. A full density matrix method was used to determine the aq(2)(p) parameters at 255 and 298 nm, where most of the signal was found to be from parallel, incoherent excitation. The data support a dissociation mechanism in which excitation occurs to a state of A′ symmetry and there is substantial bending of the ozone before dissociation.