Dynamical Theory

Abstract

The Born approximation and its Fourier transform relationships between waves and structure formed the basis for kinematical theory. Chap. 13 presents the alternative dynamical theory of electron diffraction, starting with the two-beam model that has analytical solutions of the wave equations. Bloch waves are developed as eigenfunctions of a solid with a weak periodic potential, and are related to the diffracted beams in the solid. The fundamental differences between kinematical and dynamical diffraction are explained, as is the role of the diffraction error in both. Dispersion surface constructions are presented for dynamical theory, and are used for semi-quantitative estimates of beam amplitudes through the depth of the sample, and at defects. With absorption, the two-beam dynamical theory is developed for diffraction contrast from stacking faults, and dynamical theory is used qualitatively for dislocations and other defects. The formalism of multibeam dynamical theory is developed.KeywordsDynamical TheoryDiffract BeamPeriodic PotentialBloch WaveDispersion SurfaceThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.