REACTIONS IN RARE GAS MATRICES MATRIX AND SITE EFFECTS

Recent advances in the studies of chemical reactions in cryogenic rare gas matrices are surveyed, with a special emphasis on site and matrix effects. The reactions considered include direct and sensitized photodissociation, thermal and photo-induced isomerization of molecules and molecular clusters, bimolecular reactions between neighbors and reactions involving diffusing species. Methods for simulating the structure of trapping sites and the dynamics and kinetics of chemical reactions in this low temperature medium are discussed. Even in the case of these weakly interacting solvents, a detailed theoretical analysis based on gas phase derived potentials can be made only for very elementary reactions, such as the photo dissociation of diatomic molecules. Nonetheless, approximate simulations succeed in providing an insight into the factors affecting the outcome of chemical reactions in matrices and are already being used for planning and analysing reactivity patterns and rates.