Multiple elastic scattering of core-loss electrons in atomic resolution imaging

We consider the elastic scattering of a fast incident electron both prior and subsequent to its involvement in an atomic inner-shell ionization (core-loss) event in a crystal. By using numerical simulations, it is shown that elastic scattering subsequent to ionization can strongly affect the qualitative features of atomic resolution core-loss images of crystals recorded in the scanning transmission electron microscope (STEM). This conclusion holds even for a thin crystal foil and for a relatively large detector, which is matched to the probe-forming aperture in an aberration-corrected STEM. Such a conclusion is potentially very important for the interpretation of experimental core-loss images. We also introduce an approximate model that incorporates the effects of elastic scattering subsequent to ionization in the case of a small detector.