Dynamical theory of electron diffraction for a finite polyhedral crystal. I

The multiplet structure of Debye-Scherrer rings and the splitting of Laue spots were observed recently in electron diffraction by several authors (Sturkey & Frevel, 1945; Hillier & Baker, 1945; Honjo, 1947; Cowley & Rees, 1947; Sturkey, 1948). Although these phenomena were explained by the refraction of the electron beam on the surface of micro-crystals of polyhedral shape, it may require the dynamical theory of diffraction to understand them completely. The general formulation of the theory for a finite crystal, however, is very difficult (Ekstein, 1942). One of us (Kate, 1949) previously extended Bethe's theory of electron diffraction (Bathe, 1928) to the case of a wedge-shaped crystal with an infinite lateral extension, and discussed the refraction effects. We recently tried to extend the theory further to a finite crystal of polyhedral shape. In the present note we give a summary of our results.