INFLUENCE OF PHOTOCHEMICAL EFFECTS ON IRREVERSIBLE LOSS OF ACTIVE-SITES ON SERS ACTIVE SILVER ELECTRODE

The intensity dependence of surface-enhanced Raman scattering (SERS) of pyridine adsorbed on the silver electrode at several excitation wavelengths is studied. It is found that SERS intensity decays faster if an electrode is illuminated by a green laser line than in the case of the red line. This difference of decay rate cannot be exclusively explained by the difference of electrode surface temperatures. The results show that on the surface of the silver electrode the photochemical process of irreversible incorporation of adatoms or adatom clusters into the electrode strongly sensitive to adsorbed anions takes place. We suggest that deactivation is a photochemical process caused by irreversible destruction of complexes of silver adatoms with anions.