Point-on-line coincidence in epitaxial growth of CuPcCl16 on graphite

Epitaxial growth of perchloro-copper-phthalocyanine (CuPcCl16) on graphite was studied by STM and TEM. The crystals grew epitaxially with two slightly different orientations on the graphite surface. The corresponding orientations were also observed in a monolayer of CuPcCl16 by STM. By detailed analysis of the moire-like pattern in the STM images, these orientations are interpreted as being consistent with a ‘point-on-line coincidence’ epitaxy. In order to realize the exact point-on-line coincidence for the respective orientation, the unit cell dimensions of the monolayer were slightly distorted at each orientation, although they are almost the same as the monoclinic structure of the thin film determined by TEM.