Nonadiabatic interactions in the photodissociation of ICN

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Abstract
Photodissociation of ICN in the à continuum has been modeled using classical trajectories assuming that all absorption from the linear ground state is to a single linear diabatic excited state which dissociates to form I*(2P1/2) and CN(2Σ+,v=0). It is also assumed that, in nonlinear excited state configurations, nonadiabatic transitions occur to a bent surface which correlates diabatically to ground state I(2P3/2) and CN(2Σ+,v=0). Empirical potential surfaces with frozen CN bond lengths are employed, while transitions between the surfaces are treated using either the Miller–Meyer classical electron model or a simple diabatic version of the Tully–Preston surface‐hopping model. With the above assumptions, the Miller–Meyer method is found to give much better agreement with the experimental results. Theoretical results obtained with the Miller–Meyer method are compared with recent experimental data on the I*/I branching ratio, the average CN rotational energies, and the product CN rotational distributions as a function of photolysis wavelength for λ=248, 266, 280, 290, and 308 nm. Except for the branching ratio at 248 nm, we obtain satisfactory agreement with the experimental results.