The franck—condon approximation in the theory of simple electrochemical redox reactions

Abstract

The Franck—Condon approximation is discussed within the theory of simple electrochemical redox reactions. For this purpose it is assumed that the electronic matrix element depends on the distance reactant-electrode and/or on the coordinate of an inner sphere vibration. Non-Franck—Condon contributions to the energy of activation and the transfer coefficient are estimated to be generally small, but could be noticeable when the reaction rates of a particular redox couple at various substrates are compared. An expression for the theoretical limiting current is obtained which does not depend on the Franck—Condon approximation.