MODELING THERMAL DIFFUSE-SCATTERING IN ELECTRON-DIFFRACTION INVOLVINGHIGHER-ORDER LAUE ZONES

The importance of thermal diffuse scattering (TDS) in electron diffrac tion contrast is well known. Experiments involving higher-order Laue-z one (HOLZ) reflections are highly sensitive to variations in the TDS f orm factors. The Einstein model for TDS gives excellent agreement with experimental convergent-beam electron diffraction (CBED) patterns con taining HOLZ lines provided that the absorption coefficients are not c alculated using perturbative methods but instead are evaluated exactly . This is in contrast to absorption potentials determined from experim ents sensitive to beams in the zero-order Laue zone (ZOLZ) only, the u se of which can be inconsistent with data sensitive to HOLZ beams. Her e the features of the Einstein model important for the correct interpr etation of the experimental data are analyzed and why it is inadequate to treat HOLZ beams perturbatively is discussed.