THE CT ENHANCEMENT IN SERS ON GOLD ELECTRODES - HOW IMPORTANT IS IT

The presence of a charge transfer (CT) mechanism in the surface-enhanc ed Raman scattering (SERS) from pyridine adsorbed on a gold electrode was probed by varying both the applied potential and the excitation en ergy. Sensitivity of the electrode potential at which the maximum of t he SERS intensity is observed to the photon energy provides evidence f or a CT contribution to the total enhancement factor. The magnitude of the contribution from CT enhancement was estimated to be equal to at least 4. Similar experiments performed for crystal violet show that CT enhancement is also operative for other molecules adsorbed on a gold electrode.