Observation of Charge-Transfer States for Pyridine Chemisorbed on Ag(111)

Abstract

The excited states of chemisorbed pyridine on Ag(111) have been determined with use of electron-energy-loss spectroscopy. In addition to weakly perturbed molecular states we observe new excitations above \ensuremath{\sim}1.4 eV, which we identify as metal-molecule charge-transfer excitations. These new electronic states provide an explanation for several features observed in surface-enhanced Raman scattering.