Reactions of oxygen atoms with van der Waals molecules in crossed molecular beams

Studies of reactions of van der Waals (vdW) molecules or clusters can provi de a window through which we can investigate a variety of effects of weak i ntermolecular interactions on the chemical process of interest. Here we foc us on the reactions of oxygen atoms with vdW complexes. These reactions wer e chosen since the reactions of oxygen atoms with hydrogen halides, saturat ed hydrocarbons and water molecules have been studied extensively in both t he gas and the condensed phases. In addition, the presence of a low-lying e xcited electronic state, in the oxygen atom, means that its chemistry may b e particularly sensitive to perturbations of the environment, for example t hose introduced by incorporating one or more of the reactants into a vdW co mplex. In this review we discuss association reactions of oxygen atoms with CO and WO and the reactions of oxygen atoms, both in their ground O(P-3) s tate and in the excited O(D-1) state, with saturated hydrocarbons, water an d with HCl complexes. The studies of the reactions of oxygen atoms with vdW molecules were used to gain insights into generic effects of complex forma tion on chemical reaction dynamics, reactivity and product state distributi ons. The results of these studies were summarized in several general rules that describe the effects of the 'environment' on bimolecular reactions.