Identification of enantiomorphism in crystals by electron microscopy

Abstract

Simple electron-microscopy techniques are described which allow one to detect the presence of two enantiomorphous forms of a structure within an apparent single crystal. The first method consists of a characterization of the interface between the two enantiomorphs. In the second method advantage is taken of violations of Friedel's law which can occur in non-centrosymmetric crystals. These techniques have been illustrated by an analysis of the domain structure in ordered LiFe5O8, which has a space group P4132 or P4332. Consistent results were obtained with both methods. The first method yields a more complete description of the domain structure. Methods which can be used to determine the absolute configuration of the structure in a part of the crystal are discussed.