Raman scattering of adsorbed molecules

Abstract

The excitation energy dependence of the surface enhanced Raman scattering of adsorbed molecules is calculated based on the effective resonance model for a molecule–metal system. As a consequence of the effective resonant Raman process of the adsorbed molecule, a remarkable departure from an ω⁴ law is obtained near the excitation energies which satisfy the resonant condition. The significance of the substrate metal on the degree of the enhancement is discussed with the use of a result that the position of the effective resonant level is closely connected with that of the Fermi level. A comparison with the recent experimental results on the excitation profiles is also made.