Fine Structure due to Refraction Effect in Electron Diffraction Pattern of Powder Sample Part II. Multiple Structures due to Double Refraction given by Randomly Oriented Smoke Particles of Magnesium and Cadmium Oxide

Fine structures composed of sets of doublets as expected by the double refraction effect, an effect concluded by the dynamical theory of electron diffraction, are studied in details for reflexions given by individual smoke particles of magnesium and cadmium oxides having random orientations. The configurations of doublets vary according not only to the azimuths of the crystallites but also to the angles of deviations from Bragg condition, namely, the errors of resonance of Bragg reflexions. By determining these two parameters from the configuration, the mean and periodic terms of the Fourier expansion of the inner potentials of the crystals are obtained from the inter-doublets and intra-doublets separations in the fine structures. The results show a reasonable agreement with the theoretical values. The intensity anomaly of the double refraction effect, suggested in Part I, are found to be a general phenomenon. It is observed that between the two spots of a doublet, that of larger deviation is always weaker in intensity than its companion of smaller deviation, and that the intensity difference is more conspicuous for strong reflexions, that is to say, reflexions which show large double refractions. This anomaly seems to be explained when we assume for crystals complex periodie inner potentials.