RELATIVE SERS ENHANCEMENT FACTORS FOR PYRIDINE ADSORBED ON A SILVER ELECTRODE - THE CHEMICAL EFFECT IN SERS AS A PRODUCT OF CHARGE-TRANSFER AND ACTIVE-SITE MECHANISMS

The relative SERS (surface-enhanced Raman scattering) enhancement factors for pyridine adsorbed on a silver electrode were determined as a function of the laser wavelength and applied potential. The charge-transfer (CT) effect on Raman intensity, G(CT), was determined hy analysing the relative Raman intensity as a function of the potential, taking into account voltage-dependent coverage of the silver electrode. The total chemical effect was defined as a product of G(CT) and the so-called 'active-sites' effect and was estimated as equal to about 50.