Electron-energy-loss-spectroscopy scattering profiles of vibrational overtones and double losses

Abstract

We report the first measurements of the angular dependence of electron-energy losses from vibrational overtones and double losses. The angular profiles, obtained from the spectrum of CO on potassium-precovered Ru(001), indicate that both the CO fundamental and the overtone are excited through dipole interactions; however, the double-loss profile is characteristic of an impact mediated excitation. The formation of a short-lived negative-ion resonance is proposed to account for the observed behavior.