SUBSTRATE DEFECTS AND VARIATIONS IN INTERFACIAL ORDERING OF MONOLAYER MOLECULAR FILMS ON GRAPHITE

Scanning tunneling microscopy is used to investigate monolayer films of the liquid crystal 4'-octyl-4-biphenylcarbonitrile (8CB) deposited onto highly ordered pyrolytic graphite. These self-assembled films display a wide variety of structural forms, several of which are reported here for the first time. Nanometer-resolution images provide insight into the important molecule-molecule and molecule-substrate interactions determining film structure. The role of substrate defects in determining interfacial order is discussed, and a growth mechanism is proposed to account for the infrequent observation of certain monolayer film structures reported here.