Surface ordering at the air-nematic interface. Part 2: a spectroscopic

Lau, Y.G.J. ; Klein, Susanne ; Newton Christopher J.P. ; Richardson, Robert, M.

HP Development Company

关键词: order parameter;    air-nematic interface;    ellipsometry;   

RP-ID  :  HPL-2006-168

学科分类：计算机科学（综合）

美国|英语

来源: HP Labs

【 摘 要 】

Spectroscopic ellipsometry has been used to measure enhanced orientational ordering at the nematic-air interface of 8CB as the smectic-A phase was approached by cooling from the isotropic phase. The depth profile of the orientational order has been estimated by calculating the ellipsometric parameters for a homeotropic uniaxial surface film on a uniaxial subphase using the Abeles matrix method. This showed that the depth of the enhanced orientationally ordered region was ~ 10nm at 0.5°C above the nematic-smectic-A transition. This is substantially less than the thickness of the region with surface enhanced smectic order as determined by neutron reflection and a model of the surface structure consistent with both sets of results is proposed. Publication Info: Liquid Crystals 25 Pages