Excitation of 2D plasmons in a Cs/W(110) system

The evolution of surface photoemission spectra was investigated for a Cs/W( 110) system with metastable Cs coatings larger than a monolayer. It is demo nstrated that 2D plasmons can be detected by threshold photoemission spectr oscopy. Three photoemission peaks were observed, whose dependence on the Cs adsorption dose showed a complicated behavior. The peaks may be due to the photoinduced excitation of a plasmon in quasi-2D Cs clusters, a surface Cs plasmon, or an interface Cs-W plasmon. (C) 2001 MAIK "Nauka/Interperiodica ".