Photomodulated voltammetry investigations on the benzyl radical

Benzyl radicals were generated photochemically directly in an electrochemical cell, using diphenylacetone as a precursor. The half-wave potentials and the plateau current of benzyl radical reduction and respectively oxidation were determined in acetonitrile, propylene carbonate, N,N-dimethylformamide and dimethylsulfoxide. While half-wave potentials and transfer coefficients were independent of chopper frequency and phase setting, the plateau current was markedly influenced by these parameters. The lifetime of the radical was obtained from the dependence of the phase shift of the current on the angular frequency. The influence of precursor concentration, light intensity and nature of the solvent on the radical lifetime was investigated.