Modeling Thermal Diffuse Scattering in Electron Diffraction InvolvingHigher-Order Laue Zones

Abstract

The importance of thermal diffuse scattering (TDS) in electron diffraction contrast is well known. Experiments involving higher-order Laue-zone (HOLZ) reflections are highly sensitive to variations in the TDS form factors. The Einstein model for TDS gives excellent agreement with experimental convergent-beam electron diffraction (CBED) patterns containing HOLZ lines provided that the absorption coefficients are not calculated using perturbative methods but instead are evaluated exactly. This is in contrast to absorption potentials determined from experiments sensitive to beams in the zero-order Laue zone (ZOLZ) only, the use of which can be inconsistent with data sensitive to HOLZ beams. Here the features of the Einstein model important for the correct interpretation of the experimental data are analyzed and why it is inadequate to treat HOLZ beams perturbatively is discussed.