Kinetic Ejection of Electrons from Solids

Abstract

This chapter describes the kinetic ejection of electrons from solids. The interaction of energetic beams of ions, atoms, and molecules with solids results in a variety of secondary processes. Each of the secondary processes may be quantitatively characterized by a yield coefficient. This yield coefficient may depend on its interpretation with the specific measurement techniques. The penetration of medium-energy atoms along tubes or channels to distances in excess of 1000 A has been established. The ranges of hot e1ectrons in solids have been measured in excess of 500 A in gold. It is found that accepted values of the mean penetration of atomic particles in solids, and the mean free paths of electrons with energy several electron-volts above the Fermi level have both increased considerably. Thus an appreciable fraction of the emitted secondaries may originate deep into the lattice rather than originating exclusively from the first few atomic layers. The occurrence of kinetic ejection for those cases where there are not conduction band electrons appears to rule out the retardation pulse theory. The chapter suggests that the dependence of angular and velocity distributions of emitted secondaries on the incidence angle of the bombarding ions would permit one to isolate the contribution of Auger mechanisms to the kinetic ejection process.