Electronic properties of gold thin films studied by electron energy loss spectroscopy

High-resolution electron energy loss spectroscopy was used to investigate the electronic properties of (111)-oriented Au ultrathin films grown on Cu(111). The loss spectrum showed several features which were ascribed to both single and collective excitations. In particular we distinguished features assignable to dispersionless single-particle transitions and the dispersing electron-hole continuum as well as the ordinary and s-like surface plasmon, and the multipole surface plasmon.