Journal of Chemical Physics, Vol.116, No.5, 1965-1975, 2002
Photodissociation of O-2 in the Herzberg continuum. II. Calculation of fragment polarization and angular distribution
Parallel and perpendicular components of the Herzberg I, II, and III transitions contribute to the photodissociation of O-2 in the Herzberg continuum. The photodissociation dynamics determines the O(P-3(j)), j=0,1, and 2 atomic fine-structure branching ratios and angular distributions, which were determined in ion imaging experiments at lambda=236, 226, and 204 nm by Buijsse [J. Chem. Phys. 108, 7229 (1998)]. In the preceding paper we presented potential energy curves for all eight ungerade O-2 states that correlate with the O(P-3)+O(P-3) dissociation limit, and the R-dependent spin-orbit and the nonadiabatic radial derivative couplings between these states. Here, we employ these potentials and couplings in a semiclassical calculation of the fine-structure branching ratios, atomic polarizations, and fine-structure resolved anisotropy parameters. We discuss the adiabaticity of the dissociation by comparing the results with adiabatic and diabatic models. The O(P-3(j)) 2+1 REMPI detection scheme used in the experiment is sensitive to the polarization of the atomic fragments. We predict an important effect of the polarization on the anisotropy of the j=1 and j=2 ion images at low energies (lambda>236 nm). The agreement between the semiclassical calculations and experiment is reasonable, possible explanations for the remaining differences are discussed.