Plasmon excitation in Al by keV Ne and Ar ions

We present experimental studies of plasmon excitation by keV Ne and Ar sing le charged ions on Al surfaces. Plasmons are identified through the charact eristic energy spectrum of electrons from plasmon decay. At 1 keV incident energy, surface plasmons are excited by Ne+ but not by Ar+. For higher ener gies we observe bulk plasmon excitation resulting, most likely, from excita tion by fast electrons, such as A1-2p Anger electrons, traveling inside the solid. (C) 2000 Elsevier Science B.V. All rights reserved.