Weak anchoring energy and pretilt of a nematic liquid crystal

Barbero, G. ; Madhusudana, N. V. ; Durand, G. (1984) Weak anchoring energy and pretilt of a nematic liquid crystal Journal de Physique: Lettres, 45 (12). pp. 613-619. ISSN 0302-072X

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Official URL: http://hal.archives-ouvertes.fr/jpa-00232389/

Related URL: http://dx.doi.org/10.1051/jphyslet:019840045012061300

Abstract

We extend the wedge technique of Rivière et al. to measure the pretilt angle F and the (weak) anchoring energy of a nematic liquid crystal oriented on a suitably treated glass surface. The liquid crystal is placed in a wedge shaped space formed by the plate to be studied and a « standard » plate giving a strong homeotropic anchoring. Instead of using a total reflection technique, we measure the optical path difference (Δl) between the ordinary and extraordinary waves, as a function of the sample thickness (d). From an analysis of this variation, we obtain the pretilt angle from the region of large thickness, and the anchoring energy from the region of small thickness, a domain which could not be studied with the previous technique. The transition thickness d is comparable with the extrapolation length L associated with the surface energy. Typical values of F and L for rubbed silane coated plates are ˜ 0.8 radian and ˜ 1 µm respectively.

Item Type:Article
Source:Copyright of this article belongs to EDP Sciences.
Keywords:Smectic A; Polymorphism; Reentrant Phases; Bilayer Smectics; Induced Smectic Phases
ID Code:76036
Deposited On:28 Dec 2011 13:21
Last Modified:28 Dec 2011 13:21

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