title: Direct measurement of surface-induced orientational order parameter profile above the nematic-isotropic phase transition temperature.
abstract: The spatial and temperature dependence of the surface-induced orientational order parameter S(z,T) was determined in the isotropic phase. An optical fiber was immersed in a thin liquid crystal layer and the retardation was measured as a function of the fiber's height above the surface, from which the model-independent S(z,T) was deduced with resolution <or=2 nm. It was found that (i) S(z=0) <or=0.12 close to the nematic transition temperature, (ii) the susceptibility is mean-field-like, and (iii) S(z,T) deviates significantly from exponential spatial decay. The results are discussed in terms of a nonlocal potential.
authors.affiliation: Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106-7079, USA.
authors.forename: Ji-Hoon
authors.initials: JH
authors.lastname: Lee
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Atherton
authors.forename: Valentin
authors.initials: V
authors.lastname: Barna
authors.forename: Antonio
authors.initials: A
authors.lastname: De Luca
authors.forename: Emanuela
authors.initials: E
authors.lastname: Bruno
authors.forename: Rolfe G
authors.initials: RG
authors.lastname: Petschek
authors.forename: Charles
authors.initials: C
authors.lastname: Rosenblatt