Spin-Orbit Interaction on Potential Energy Surfaces Involving Halogen Atoms

Abstract

The role of spin-orbit interaction in reaction dynamics so far has been little studied. The current state of experimental work has recently been reviewed by Dagdigian and Campbell [1]. Many experiments have focussed on the reactivity of spin-multiplet states of metastable electronically excited inert gas, alkali and alkaline earth atoms. The product spin-multiplet states of halogen atoms have also been investigated for a number of halogen atom-hydrogen halide [2,3] and halogen atom-halogen molecule [4–7] reactions. Such measurements give information on the form of the low lying potential energy surfaces and their mutual interaction arising from spin-orbit interaction. The strength of spin-orbit interaction varies strongly along the homologous series of halogen atoms. Hence reactions involving halogen atoms may be expected to exhibit a variety of effects arising from spin-orbit interaction [1]. However there have been very few calculations of reaction potential energy surfaces which have included spin-orbit interaction, a notable exception being the diatomics-in-molecules (DIM) calculation of the F + H2 potential energy surface by Tully [8]. DIM calculations [9–11] of potential energy surfaces involving more than a single halogen atom have recently been extended to include spin-orbit interaction [12–14], in order to investigate the forms of interaction which may be encountered in such halogen systems.