Nature of the Active Site in Surface-Enhanced Raman Scattering

Abstract

Experiments involving competitive and cooperative adsorption of pyridine, ${\mathrm{Cl}}^{-}$, SC${\mathrm{N}}^{-}$, and Tl, and voltage induced resonance shifting show that the largest surface-enhanced Raman scattering intensity comes from complexes of these species adsorbed on defects which cover less than 3% of the Ag surface. The resonance is attributed to charge transfer excitation from Ag to pyridine and from SC${\mathrm{N}}^{-}$ to Ag which is communicated to all vibrations of the complex.