Adiabatic Rate Processes at Electrodes. I. Energy-Charge Relationships

The distinction between adiabatic and nonadiabatic reaction mechanisms at an electrode/solution interface is emphasized; in general, only adiabatic or near-adiabatic paths are important in thermally activated reactions. The role of the dielectric in determining the course of such reactions is discussed. A general interpretation of the transfer coefficient and an account of the activation process in simple systems are given in terms of the distribution of electron charge density in the transition state; these are shown to be in good accord with experiment. The conventional approach to these problems, in which an approximate potential-energy path for the reaction is calculated from intersecting potential-energy curves for the initial and final states of the system, is criticized, and an alternative representation in terms of charge variation is proposed.