Nonadiabatic photodissociation dynamics of ICN in the A continuum: A semiclassical study

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Abstract
The photodissociation dynamics of ICN in the A continuum was studied at several selected photolysis wavelengths using the semiclassical method. The calculations were performed on a set of new potential energy surfaces based on recent ab initio calculations. Classical trajectory calculations 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 functions of the photolysis laser wavelength. The CN fragment rotational state population, alignment, and spatial anisotropy parameters were calculated for the dissociation at 266 and 249 nm. The results of our calculations agree well with the corresponding experimental observations. Our calculations were performed based on a model in which five excited state surfaces [i.e., 3Π0+(A’), 1Π1(A’), 1Π1(A‘), 3Π1(A’), and 3Π1(A‘)] are involved in the A continuum absorption and the consequent dissociation dynamics. At the low energy side of the A continuum, the initial excitation involves the 3Π0+ and 3Π1 states, whereas the 3Π0+ and 1Π1 states are mainly responsible for the absorption in the shorter wavelength region. Different nonadiabatic interactions of the Renner–Teller pair of the 1Π1 states with the 3Π0+ state, as well as the reduction of the CN rotational excitation on the diabatic 3Π0+(A’) surface at large internuclear distance are the key features of this model.