Computation and interpretation of contrast in crystal lattice images formed by inelastically scattered electrons in a transmission electron microscope

With modern transmission electron microscopes elemental mapping with atomic resolution seems feasible. For crystalline specimens the interpretation of contrast in such energy-loss micrographs is not a simple straightforward matter, as the so-called preservation of elastic contrast can play an important role. Hence the computation of theoretical micrographs for comparison is necessary. The calculation method presented in this article is based on well-known theoretical approaches. To enable numerical evaluation we use an exciton-like representation for the excited electronic state of the crystal. The practicability of this method is demonstrated by computing lattice fringes and demonstrating the influence of the preservation of elastic contrast.