Selection rules for the charge transfer enhancement mechanism in SERS: dependence of the intensities on the L-matrix

Given the similarity between the charge transfer mechanism in the SERS effe ct and the resonance Raman (RR) process, the strongest enhanced bands in th e SERS spectra can be explained through the Franck-Condon factors (A-term i n RR). These factors are numerically related to the DeltaQ vector, which re presents the displacement of the potential energy minimums of the two state s involved in the resonant process along each normal coordinate. DeltaQ is calculated through the transformation DeltaQ = L(-1)DeltaR and related to t he intensity of the band by Peticolas' equation. The dependence of the Delt aQ displacements and therefore of the calculated intensities on the L-matri x has been studied for the SERS spectra of pyridine. (C) 2001 Elsevier Scie nce B.V. All rights reserved.