The photodissociation dynamics of OClO in the near ultraviolet (UV) was investigated in a state specific and energy selective manner. At a dissociation wavelength of 308 nm, OClO( 2B1)
was excited to the OClO( 2A2(18,0,0))
state, from which it decays into ClO(X 2Π3/2,1/2)
The nascent oxygen fragments were detected spin selectively by resonant enhanced multiphoton ionization and time of flight measurements (REMPI-TOF). Based on the measurements and the conservation of energy and linear momentum, the internal energy of the ClO partner fragment was obtained. On average, more than 60% of the available energy is transferred into internal excitation of the ClO radical. Nearly the whole internal energy is vibrational energy with vibrational levels populated up to the energetic limit. Besides, the internal energy depends on the oxygen spin-orbit state because the fraction of highly excited ClO fragments increases with increasing total angular momentum J.
The bimodal behavior of the fragment energy distribution indicates two different dissociation pathways, in which one leads to ClO radicals excited up to v = 10
and the other one up to v = 15.
Furthermore, the decay is anisotropic, which was proved by polarization experiments. This is a hint for a short decay time estimated to be in the order of a few hundred femtoseconds. © 1997 American Institute of Physics.