PHOTODISSOCIATION OF OZONE IN THE HARTLEY BAND - FLUCTUATION OF THE VIBRATIONAL-STATE DISTRIBUTION IN THE O-2((1)DELTA(G)) FRAGMENT

The photodissociation of O-3 in the Hartley band has been investigated by high-resolution photofragment translational spectroscopy (PTS). At lambda(diss)=248 nm we determined the quantum yield of the dominant decay channel leading to O-2((1) Delta(g))+O(D-1) and the fragment vibrational state distribution. The fragment recoil anisotropy (beta=1.25+/-0.15) was found to be independent of the fragment vibrational states. Between lambda(diss)=275 and 295 nm beta assumes a value of 1.6+/-0.2, which exceeds the value expected for a simple impulsive process. Photofragment yield measurements carried out by PTS between 272 and 286 nm revealed a strong fluctuation of the vibrational state distribution with lambda(diss). Based on the small but distinct structure superimposed on the broad continuum of the Hartley band and the findings of recent 3D wave packet calculations, we propose this fluctuation, a manifestation of wavelength-dependent partial cross sections, to arise predominantly from an interference effect. The latter occurs between the part of the initially prepared wavepacket which propagates directly into the exit channel and a (minor) part which is temporarily trapped by the motion of the bending and symmetric stretching modes in the excited O-3 molecule. (C) 1995 American Institute of Physics.