Identification of chirality of enantiomorphic TaSi2 crystallites by convergent-beam electron diffraction

The chirality of domains in enantiomorphic TaSi2 crystallites produced by co-sputtering and subsequent annealing has been determined by convergent-beam electron diffraction (CBED). TaSi2 possesses the hexagonal C40 structure that belongs to either the space groups P6(2)22 (right-handed) and P6(4)22 (left-handed). Two different CBED methods are employed to determine the chirality of each domain, both of which methods involve comparison of an experimental CBED pattern with a computer simulated one. In one method, the appearance of a structure factor invariant line that appears in a specific first-order Laue-zone (FOLZ) disk in a non-symmetric CBED pattern is inspected. In the other method, asymmetry in the intensity of Bijvoet pairs of FOLZ disks in a symmetrical zone-axis CBED pattern is inspected. Both methods successfully identify the chirality of each domain in the TaSi2 crystallites. Effects of zone-axis orientation as well as crystal thickness on the applicability of these two methods for identification of the chirality are briefly discussed.