Mechanisms for plasmon production by highly charged neon ions interacting with an Al surface

Low-energy electrons ejected by 1-4 keV Ne4+ ion impact on an Al surface we re measured. Spectral structures found near 11 eV were attributed to the de cay of plasmons induced by potential energy of the projectile. The data wer e used to determine absolute values for electron yields from the plasmon de cay, which were primarily studied as a function of the incidence angle of t he Ne4+ projectile. Strong variations of the plasmon yield are observed whe n the angle of incidence reaches that of specular reflection indicating sig nificant changes in the contributions to plasmon production from below and above surface.