Surface Sensitivity and Detection Depth for Electron Spectroscopy

Four physical parameters describing the inelastic scattering of electrons, which is a measure of surface sensitivity, were described. The definitions of four parameters, namely, inelastic mean free path (IMFP), mean escape depth (MED), effective attenuation length (EAL), and information depth (ID), are given, and their determination methods and predictive equations were explained. Most of these equations are also applicable to hard X-ray photoelectron spectroscopy. At this time, the author concludes that IMFP and MED are the most appropriate parameters to describe surface sensitivity and detection depth from the standpoint of clarity of definition and practicality.