NONADIABATIC PHOTODISSOCIATION DYNAMICS OF ICN IN THE A CONTINUUM - ASEMICLASSICAL STUDY

The photodissociation dynamics of ICN in the A continuum was studied a t several selected photolysis wavelengths using the semiclassical meth od. The calculations were performed on a set of new potential energy s urfaces based on recent ab initio calculations. Classical trajectory c alculations were carried out on these surfaces while the nonadiabatic interactions were treated by the surface-hopping model. The absorption cross section and the I/I branching ratio were calculated as functio ns of the photolysis laser wavelength. The CN fragment rotational stat e population, alignment, and spatial anisotropy parameters were calcul ated for the dissociation at 266 and 249 nm. The results of our calcul ations agree well with the corresponding experimental observations. Ou r calculations were performed based on a model in which five excited s tate surfaces [i.e., (3) Pi(0)+(A'), 1 Pi(1)(A'), 1 Pi(1)(A''), (3) Pi (1)(A'), and (3) Pi(1)(A'')] are involved in the A continuum absorptio n and the consequent dissociation dynamics. At the low energy side of the A continuum, the initial excitation involves the (3) Pi(0)+ and (3 ) Pi(1) states, whereas the (3) Pi(0)+ and (1) Pi(1) states are mainly responsible for the absorption in the shorter wavelength region. Diff erent nonadiabatic interactions of the Renner-Teller pair of the (1) P i(1) states with the (3) Pi(0)+ state, as well as the reduction of the CN rotational excitation on the diabatic (3) Pi(0)+(A') surface at la rge internuclear distance are the key features of this model.