Studies on the photodissociation dynamics of HI molecule within the A band range

The photodissociation dynamics of HI molecule has been studied within the A band range. Partial and total extinction cross-sections are obtained from numerical calculations. The frequency dependent branching fraction is determined and agrees with the experiment. The curve-crossing probabilities are derived resorting to the anisotropy data of fragmentation product and the one-dimensional Landau-Zener model is used to examine the possibility that nonadiabatic mechanism occurs in the dissociation process. The results suggest that the contribution of nonadiabatic mechanism to HI photofragmentation, which may be caused by spin-rotational coupling, is not significant over the low energy part of the A band and thus can be ignored, although the angular distribution is less anisotropic in this energy regime.