Bulk and surface plasmon excitation in the interaction of He+ with Mg surfaces

We report on studies of plasmon excitation in Mg under the impact of slow He+ ions in the incident energy range 0.1-0.5 keV. Consistent with studies on Al surfaces, a transition from surface to bulk plasmon excitation occurs as the energy of the ion is increased. Previous methods in the literature to obtain information about yields of electron emission from plasmon decay are discussed. A new data analysis procedure is presented, which allows disentangling the contributions to the experimental spectra arising from different emission mechanisms, showing that potential excitation of multipole surface plasmons gives an important contribution to electron emission. (C) 2003 Elsevier B.V. All rights reserved.