Bulk plasmon excitation in the interaction of Ne+ and Ar+ ions with polycrystalline Al surfaces

We report experimental studies of electron emission from decay of bulk plasmons excited in the interaction of slow single charged Ne and Ar ion with polycrystalline Al surfaces. To answer the question of whether bulk plasmons can be excited by charged particles moving outside the surface, we performed measurements as a function of emission angle. Our experiments show that bulk plasmon excitation occurs inside the solid for incident ion energies above a threshold of similar to1 keV. Bulk plasmon excitation in Al by keV single charged Ne and Ar ions is caused by fast electrons traveling,hts inside the solid, which are energized in collisions initiated by the projectile. (C) 2001 Elsevier Science B.V. All rights reserved.