Depletion of Molecular Vibrational Modes through Electron Impact and Evidence for Resonance Dissociation to Neutrals in CondensedCH3Cl/Graphite

Abstract

We have employed high resolution electron energy loss spectroscopy to measure the depletion of the vibrational mode intensities of an adsorbed target molecule as a result of electron impact and as a function of incident energy. This new technique sums over all molecular decay channels in which a (specific) molecular bond is broken by the incident electron, irrespective of the fate of the fragments (ions or neutrals). In the case of the model system which we consider, physisorbed ${\mathrm{CH}}_{3}\mathrm{Cl}/\mathrm{graphite}$, we isolate a resonance in the depletion cross section at 3 eV, which also provides the first direct evidence for the dissociation of a negative ion resonance state into neutral fragments.