Binary-Encounter Electron Emission

Abstract

Bombardment of atoms by fast ions gives rise to the emission of energetic electrons by kinetic processes. These electrons are distributed over a wide energy range, and hence provide a continuum energy spectrum which generally has no sharply defined high-energy end. High-energy electrons are emitted preferentially in the forward direction, as is clearly observed in experiments using gas targets. The emission of high-energy electrons is of primary interest here since it is sensitive to the high-energy shadowing effect in a crystal target. The hard collision processes producing high-energy electrons can be described by the binary-encounter model, which was developed essentially from the early work described in “Ionization by moving electrified particles” by Thomson [23]. This chapter presents an outline of the binary-encounter theory and some notable results useful for the discussion in later chapters.