Surface-enhanced hyper-Raman scattering and surface-enhanced Raman scattering studies of electroreduction of phenazine on silver electrode

Surface-enhanced hyper-Raman scattering (SEHRS) and surface-enhanced Raman scattering (SERS) have been employed to study phenazine adsorbed on the sil ver electrode surface at various negative potentials. It was observed that the scattering spectra of phenazine change drastically in frequencies and i ntensities with the change of applied potential, resulted from the electror eduction of phenazine (P) as the electrode potential moves negatively. The product of the electroreduction, 5,10-dihydrophenazine (PH2), as well as in termediate species, monoprotonated phenazine (PH+), phenazine semiquinone r adical (PH.) and protonated semiquinone radical (PH2.+) have been detected by SERS. One of the intermediate species, PH2.+ radical, was also detected by SEHRS. (C) 2000 Published by Elsevier Science B.V.