Nonadiabatic interactions in the photodissociation of ICN

Abstract

Photodissociation of ICN in the A 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(2∑+,ν= 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(2∑ +,ν=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. © 1986 American Institute of Physics.