Abstract
In this work, a formal theory of electron scattering is presented from first principles by use of the many-body scattering theory. We investigate both the elastic and inelastic scattering of an electron from solids. In particular the correction terms due to elastic scattering in solids are considered to the Bethe's amplitude in high energy electron energy loss spectra; explicit formulas for seven different correction terms are given here. Other complicated scattering processes, for example, in which an electron suffers a core and a plasmon excitation successively, are also studied here. The optical potential to describe elastic scattering is also discussed within the present theoretical framework.