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

[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

[发布机构] HP Development Company

[学科分类] 计算机科学（综合）

[关键词] order parameter;air-nematic interface;ellipsometry