Kinetic energy analysis of O(3P0) and O2(b1Σg+) fragments produced by photolysis of ozone in the Huggins bands

The velocity profile of O-2 (b(1)Sigma(g)(+), v=0) produced by photolysis of O-3 in the Huggins band region at 351.4 nm has been measured using a delayed pulsed field extraction time-of-flight technique confirming that this fragment is formed by single-photon absorption. The velocity profile of O(P-3(0)) produced by photolysis at 322.64 nm has also been obtained. O(P-3(0)) fragments are shown to be produced in coincidence with O-2 (X (3)Sigma(g)(-)), O-2 (a (1)Delta(g)), and O-2 (b (1)Sigma(g)(+)). The relative contribution of each of these channels to the total O(P-3(0)) signal is reported and it is shown that spin-forbidden channels dominate the dissociation process at this wavelength. Two quite different primary crossings of the initially excited state are suggested to account for the change in the relative contribution of these three channels when photolysis is changed from resonance with a vibronic band of ozone to an off-resonance wavelength. The determination of the anisotropy parameter, beta(v), for these dissociation processes suggests that the transition dipole responsible for all of the Huggins band absorption has B-2 symmetry. (C) 1999 American Institute of Physics. [S0021-9606(99)01121-6].