SOME NOTES ON THE SELECTION OF STRUCTURAL CHIRALITY BY CBED

A simple experimental indication of the Fourier coefficients which are sensitive to hand is given in CBED patterns by those non-zero Laue zo ne reflections which clearly break a mirror line that is present in th e zero Laue zone. It has been found possible to determine the chiralit y of thin crystals of Ho2Ge2O7 and of Bi12GeO24 by interpreting the re lative intensity of such reflections with a three-beam calculation. Mu ltislice calculations which matched the experimental patterns gave the same chirality. It is found that projections which contain mirrors ar e the most practical to use since they can be easily aligned.