Abstract
The inclusion of (e, 2e) scattering kinematics in describing ionization events in crystals yields insight into the basic physics which determines the ionization probability. The development of this new approach to ionization in crystals, that also takes into account dynamical diffraction of the fast electron, is important in understanding the influence of excitation site and diffraction conditions on the cross-section for ionization. The ‘overlap integrals’ of transition matrix elements with non-aligned wave-vectors give the site-dependent contribution to excitation probability. These transition matrix elements require proper account to be taken of both amplitude and phase when integrated over all possible directions of ejection for the excited electron. The implications that this theory has on localization and diffraction contrast in rocking curves and Kikuchi bands are contrasted with earlier theories. Existing experimental data from the ionization of Al and Mg in spinel tends to support the validity of our (e, 2e) approach to ionization in crystals.