PHOTODISSOCIATION OF HCL+ MGO(001) - THE STATIC AND DYNAMIC EFFECTS OF THE SURFACE/

The photodissociation dynamics of surface-adsorbed HCl+ is studied usi ng both time-dependent and time-independent quantum mechanical methods . The photodissociation line shapes and photofragment angular distribu tions are calculated following excitation to the (2)(2) Sigma and the (2)(2) Pi electronic states, correlating with Cl+ + H and with Cl + H, respectively. Complementary insight is gained by analyzing also the classical photodissociation dynamics. We find pronounced shifts and mo difications of the photodissociation line shapes, which depend sensiti vely on the fragmentation channel and reflect surface-induced modifica tion of the adsorbed state and the excited HCl+ potential energy surfa ces. The quantum mechanical angular distributions exhibit a rich, ener gy-dependent structure, which differs substantially for the two fragme ntation channels. Assisted by the classical trajectory results, we asc ribe the structure to surface-induced rainbow scattering. The sensitiv ity of the photodissociation line shape and the angular distribution t o the initial orientation of the adsorbate and to details of the subst rate-adsorbate interaction in the excited manifold is illustrated. (C) 1995 American Institute of Physics.