Study of electron-specimen interactions

In the last four decades a variety of microscopes have been developed. Now the electron microscopes have well been established and become one of the most important tools to investigate the fundamental properties of electron-specimen interactions. When an electron beam irradiates a specimen, the resulting elastic scattering process canbe used to form images and diffraction patterns in the TEM, while the inelastic scattering induces secondary emissions, such as secondary electrons. Auger electrons and X-rays, which are the signals in the SBM, TEM, and STEM. EELS, an important analytical technique, which can be carried out only in the TEM or STEM, provides a direct access to the full information resulted from elastic and inelastic mixed scattering processes in the electron-specimen interactions. This thesis is concentrated on understanding the physical processes for signal generation in microanalysis. For SEM we have developed a detailed quantitative model to describe the production and escape of SE. For Monte Carlo simulation, a modified Rutherford formula has been proposed in order to obtain a satisfactory accuracy and more convenient computer procedure. For EELS, a new method to remove plural scattering and determine the local thickness of a specimen has been developed. This thesis also develops and applies an experimental method for the determination of stopping power in the low and medium energy range . The ionization of atoms by electrons is an important process in microanalysis. In this thesis we present the calculations of ionization cross sections of K , L and M shells covering the entire periodic table and sparming the energy range from the critical ionization energy up to 100 keV using Hartree-Slater self- consistent field model. In order to provide convenient access to this data some empirical formulae are derived, providing good quality fits to the computed results.