K+CH3I -> KI+CH3 revisited: the total reaction cross section and its energy and orientation dependence. A case study of an intermolecular electron transfer

The dynamics of the K + CH3I reaction is discussed with special reference t o two factors that govern the electron transfer. One is that at higher coll ision velocity the behavior need not be adiabatic so that there can be a fi nite probability for the electron not to transfer, resulting in no reaction . The other is the marked increase of the electron affinity of CH3I with it s bond extension. The electron transfer can therefore take place at much la rger separation of the reactants if CH3I is stretched. The barrier to react ion is then much lower. These observations are used to discuss the stereody namics of the reaction. Several open problems are identified.