Theoretical analysis of nonadiabatic effects on the predissociation of theA 2Σ+ state of OH

Multichannel scattering calculations are used to determine the role of nonadiabatic interactions on the predissociation dynamics of several vibrational levels of the A 2Σ+ state of OH and the resulting oxygen atom fine structure branching ratios. Nonadiabatic effects are found to be very strong for the lower predissociative vibrational A 2Σ+ levels and to remain nonnegligible even for the higher vibrational states of A 2Σ+ despite the considerable degree to which the asymptotic fragment kinetic energy exceeds the oxygen atom fine structure splittings. Nonadiabatic effects generally increase in importance with the final total angular momentum J of the A 2Σ+ state because of the increased Coriolis couplings, but the spin sublevel and parity are of minor importance except at low energies. The oxygen atom fine structure branching ratios are shown to provide a qualitative probe of the predissociation pathway. Certain conditions are presented under which a good approximation to the branching ratios can be obtained by simple analytical treatments without the necessity of performing multichannel scattering calculations.