Lattice defects in organic crystals revealed by direct molecular imaging

摘要

The arrangement of molecules at crystal defects in organic crystals was examined with a high-resolution electron microscope, and the results from two examples are discussed from the viewpoint of the molecular interaction around the fault. The stacking fault found in a charge transfer complex of K(+)TCNQF(4)(-) (TCNQF(4)(-) drop tetrafluoro-tetracyanoquinodimethane) is interpreted to be a defect produced by the deficiency of one molecular plane along the (001) or (010) plane. An edge dislocation found in a quaterrylene thin crystal is made by two excess half-planes along the a axis without forming stacking faults. At the core of the dislocation, some unpaired molecules are located to fill the spaces produced by the edge dislocation, although the molecules in the perfect crystal are packed in the sandwich herringbone-type arrangement (paired molecules). [References: 15]