Molecule Adsorbed on Metal Surface–Role of Electron-Hole Excitation in Metal–

Fano's treatment for the interaction between a discrete level and a continuum state is used to calculate the eigenstates of molecules adsorbed on a metal surface, where both surface plasmon and electron-hole pair excitations due to the Coulomb field of the molecular dipole are taken into account. Spectral density of states of adsorbed molecules shows more broadened structure than that calculated by a simple image dipole model. The role of electron-hole excitations on the Raman scattering of adsorbed molecules is then investigated.