Structure analysis of single crystals by electron diffraction. I. Techniques

Abstract

The possibility of using single-crystal electron diffraction patterns from very small crystals for structure analysis by Fourier methods is discussed. It is pointed out that the crystals used must be no more than a few hundred Angstr6m units thick in order to avoid modification of the intensities of the reflexions by dynamic interaction or secondary diffraction. The principal experimental difficulties axe:the manipulation of the specimen and the measurement of the intensities. A new method of intensity measurement, involving the photographic recording of spots spread out by periodic potentials applied to a set of deflecting plates, is described and illustrated. The inter-pretatibn of Fourier projections of the potential distribution in a crystal is considered.