Intensity profiles for fringe patterns due to planar interfaces as observed by electron microsocpy

Fringe profiles occuring at planar interfaces are discussed on the basis of a new simple theory. The theory can be used to derive the contrast at stackïng faults or antiphase boundaries (Ct-boundaries), coherent domain walls (δ-boundaries), and at coherent interfaces cf a mixed nature ( (α-δ )-boundaries), Explicit expressions for the transmitted intensity I_T and the scattered intensity I_S are derived from the dynamic two-beam theory for electron diffraction, taking anomalous absorption into accounts. The effect of the various physical parameters involved is analysed on the basis of these expressions. Very fine image details can be explained or predicted, which lead to identification
of the physical origin of the observed contrast features, and enable the sign of α to be determined. The analysis is supported by computed profllas, and a particular case is discussed for which the present method is applicable.