SUBSTRATE DEFECTS AND VARIATIONS IN INTERFACIAL ORDERING OF MONOLAYERMOLECULAR FILMS ON GRAPHITE

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