FORMATION OF EPITAXIAL TWINS BY PERFLUORO-N-ALKANE EVAPORATED ON ALKALI-HALIDE CRYSTAL

Structural evaluation of perfluoro-n-alkane, CF3(CF2)(18)CF3, thin films evaporated on KC1(001) single crystal was performed using a recently developed total reflection X-ray diffractometer. The molecular chain axes of the perfluoro-72-alkane crystals in the evaporated films were revealed to be normal to the substrate. where, the molecules assembled in hexagonal symmetry and grew epitaxially on the KC1(001) surface with fourfold symmetry, arranging their [100](hex) directions along the [100] directions of the KC1 crystal. Furthermore, detailed analysis suggested that the epitaxially grown crystals form a slightly distorted twin with facing their (1 $($) over bar$$ 430) planes, referred to here as an ''epitaxial twin''.