Evidences for the contribution of a resonant charge transfer process to the surface-enhanced Raman scattering of 2,6-dimethylpyridine

The surface-enhanced Raman scattering spectra of 2,6-dimethylpyridine have been recorded on silver at different electrode potentials. The main feature of these spectra is the strong enhancement of the band corresponding to the 8a mode when the electrode potential becomes more negative. This enhancement has been discussed on the basis of a resonant charge transfer (CT) mechanism by using a methodology based on the analysis of the ab initio optimized equilibrium structures of the electronic states involved in the CT resonant process namely: the ground electronic states of the neutral molecule and its radical anion.