SCIPRESS FORMA
Forma, Vol. 13 (No. 4), pp. 351-362, 1998
Original Paper

STM Images of Molecular Alignments in Monolayers of Cyanobiphenyl Liquid Crystals on Graphite and MoS2 Substrates

Seiji Taki and Shoichi Kai

Department of Applied Physics, Faculty of Engineering, Kyushu University, Fukuoka 812-8581, Japan

(Received October 13, 1998; Accepted December 15, 1998)

Keywords: Keywords: STM, Liquid Crystals, Molecular Alignment, Mixture Alignment, Odd-Even Effects

Abstract. Abstract. The systematic observations were carried out for the molecular alignments of the monolayers of homologous series in cyanobiphenyle (CB) liquid crystals such as 6CB to 12CB on highly oriented pyrolytic graphite (HOPG) substrates using scanning tunneling microscopy (STM). For the monophase of 6CB and two phase mixtures from 8CB to 12CB, the STM image of the molecular alignments were obtained on molybdenum disulfide substrates (MoS2). In nCB with n = odd number, only the single row property of the monolayer alignments was observed. The monolayer alignments of nCB with n = even on the other hand showed double row characteristics. Thus all the observed aspects clearly indicated the odd-even effect of carbon numbers in alkyl chains. The morphology of the molecular alignments due to the odd-even effect in the monolayers of cyanobiphenyl liquid crystals on HOPG and MoS2 were systematically determined. Specific features on dislocations in their epitaxial growth were also observed.