Electron-Electron Interactions and the Depth Sensitivity of Electron Spectroscopies

Abstract

Detection of an element from the near-surface region of a solid often involves the measurement of an electron energy characteristic of a particular atom. The depth resolution of these techniques is then determined by the thickness of the material that an emitted electron can traverse without undergoing an inelastic event and thus altering the electron energy. We consider these inelastic electron processes in order to obtain a quantitative understanding of the thickness of the analyzed layer. An understanding of these phenomena is particularly useful in the design of surface studies, as an experimenter can often choose the electron energy and thus determine the depth probed. In this chapter, we use the particle-scattering concepts developed in Chapters 2 and 3 to derive classical relations for electron-electron collisions. These provide a guide for useful approximations for electron escape depths and impact ionization cross sections.