Voltammetry of surface electrodimerization processes. Application to the oxidation of adsorbed 2-mercaptoethyl ether on mercury

The theory for surface dimerization reactions under linear voltammetric con ditions, and in the absence of mass transport complications, has been exten ded to remove the kinetic constraints of previous treatments. The solution of the initial value problem is shown to be identical when reactant and pro ducts remain in the adsorbed state and when the adsorbed reactant is allowe d to equilibrate with its bulk concentration at any potential. Analytical e xpressions for the voltammetric waves are derived for some kinetic limits o f interest, and empirical equations are developed to relate the peak coordi nates and wave width with experimental variables when only numerical soluti ons are available. Theoretical predictions are applied do the analysis of t he oxidation of adsorbed 2-mercaptoethyl ether on mercury, which is shown t o consist of a monoelectronic exchange followed by a fast reversible dimeri zation.