摘要
Calculation of the dimensionless excited state displacements (ESD) using density functional theory (DFT) was used to estimate the resonance Raman cross sections of pyridine on Ag clusters using the time-correlator formalism. The model systems studied are supermolecules consisting of Ag clusters with bound pyridine, Pyr(Ag)n (n = 2, 4, 8, 14 and 20). It was found that structural changes in pyridine observed in the ESD for all five Pyr(Ag)n supermolecular clusters were essentially equivalent, and similar to those observed for the strongly allowed 168 nm transition of free pyridine. Enhancements of 鈭?03-106, were calculated for all Pyr(Ag)n, which is comparable to the overall surface enhanced Raman spectroscopy (SERS) effect in studies of pyridine on Ag, suggesting that resonance Raman may be a significant contributor to the effect.