Resonance Raman enhancement of pyridine on Ag clusters

► Ground and excited state geometry optimizations of pyridine on Ag. ► Calculates serve as starting point for time correlator methods. ► Raman cross sections calculated employing the two-time correlator method valid for all frequencies and temperatures. ► Results suggest that resonance Raman could be the dominate mechanism in SERS. ► Both charge transfer and metal d → p band transitions can couple to Raman active modes.