The dependence of the photocurrent at the metal-electrolyte interface on electrode potential

Abstract

The Gurney theory of charge transfer at the metal-electrolyte interface is extended to the case of photoemission. It is found that the simple Gurney model is not sufficient to explain the results observed by a number of independent workers. In order to explain the observed linear dependence of the 0.4 power of the photocurrent on electrode potential it is found necessary to allow explicitly for the existence of a layer of solvent molecules at the metal surface. This layer of molecules con- stitutes a potential energy barrier to electron transfer with a width of about 0.28 nm and a height (with respect to the Fermi level of the metal) of about 560 kJ mol^-1 for water. The model is geometrically quite similar to that used in the very successful Brodsky model but differs in physical interpretation of the surface potential energy barrier.