Vibrations of adsorbed alkali-metal atoms: Na on Cu(111)

Abstract

Vibrations of alkali-metal atoms adsorbed on a metal surface are observed by electron-energy-loss spectroscopy. From the loss intensity recorded for Na on Cu(111) a dynamic dipole charge of 0.5e is obtained at low alkali-metal coverage. The dynamic dipole charge is found to decrease gradually with increasing coverage making the loss peak due to Na vibrations difficult to observe for coverages above approximately half of a full monolayer.