Spin-orbit branching in the photodissociation of HF and DF.: I.: A time-dependent wave packet study for excitation from v=0

The photodissociation dynamics of HF and DF, following A (1)Pi <-- X (1)Sigma(+) electronic excitation, are examined using time-dependent wave packet techniques. The calculations are based on new multireference configuration interaction calculations of the potential energy curves and complete active space self-consistent field calculations of the off-diagonal spin-orbit coupling matrix elements. The calculated branching fraction for the formation of excited state fluorine, F*(P-2(1/2)), following excitation from the ground vibrational state (v=0) of HF, agrees well with the value of 0.41 +/- 0.08 measured experimentally at 121.6 nm by Zhang [J. Chem. Phys. 104, 7027 (1996)]. Predictions are made for the excited spin-orbit state branching fraction for both HF and DF over a wide range of photon excitation energies. The results for HF and DF are discussed in context with the corresponding results for the photodissociation of HCl and DCl. (C) 2000 American Institute of Physics. [S0021-9606(00)01529-4].