Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, Vol.269, 111-123, 1995
Spontaneous Orientation of Alkyl and Alkoxy Cyanobiphenyl Liquid-Crystals on the Metallic Substrate
Infrared reflection absorption spectroscopy (IR-RAS) was applied to analyze the spontaneous orientation behavior of alkyl and alkoxy cyanobiphenyl liquid crystals on the metallic substrate. The long axis of the liquid crystal molecules was shown to orient perpendicular to the substrate plane. The orientation function was evaluated from the relative intensity of the CN stretching vibration and the out-of-plane deformation of the biphenyl ring. The temperature dependence of orientation functions was studied using a heating and cooling apparatus. The orientation functions gradually decreased with the rise in temperature in the liquid crystal phase and fell off to the range of 0.1-0.2 above liquid crystal - isotropic transition. The orientation function of the terminal methyl group was evaluated from the relative intensity of the symmetric and asymmetric stretching vibrations of the methyl group. The orientation of the methyl group was discussed in relation to the conformation of the methylene sequence.