ELECTRIC-FIELD-INDUCED OPTICAL-ROTATION IN THE PRETRANSITIONAL ISOTROPIC REGION OF CHIRAL NEMATIC LIQUID-CRYSTALS

Measurements of the effect of an electric field on the pretransitional optical rotation in the isotropic phase of chiral nematic liquid crystal mixtures of (S)-4'(2-methylbutylphenyl)-4-n-decyloxybenzoate (CE6) and n-pentylcyanobiphenyl (CB5) are reported. Experiments were performed using an alternative technique for measuring circular birefringence in the presence of linear birefringence. The optical rotation results obtained fitted well with the existing theory of pretransitional optical activity. The critical temperature obtained from data fits varied as the square of the applied voltage as expected from the Landau-de Gennes theory. For some mixtures, the optical rotation changed sign on the application of a large electric field. © 1995 The American Physical Society.