High-Resolution Electron Energy Loss Spectroscopy (HRE-

We present a High-Resolution Electron Energy Loss study of an 11-mercaptoundecanoic acid self-assembled monolayer (SAM) adsorbed on Au(111). This work has to be placed in the general context of the study of thin organic layers by HREELS and of low-energy interaction mechanisms of electrons with large organic molecules. Evidence is presented here for two resonance phenomena, at 1.5 eV and at 6 eV, respectively. The first one is attributed to a negative ion resonance involving the carboxylic group, and the second one is the well-known resonance of CH2. From the angular distribution of the elastically scattered electrons the crystalline domain size of the monolayer is estimated to be about 100 Å