Dielectric quenching of the electric polar surface instability in a nematic liquid crystal

The existence of polar electro-optic effect induced by a surface polarization of a nematic liquid crystal is proved using a simultaneous action of vertical dc and high-frequency ac electric fields on the homeotropically aligned nematic liquid crystal with positive dielectric anisotropy. The proposed method enables us to measure the surface electric polarization and the anchoring energy in the course of the same experiment. The evaluated surface polarization for the pentylcyanobiphenyl--silicone elastomere interface is 1 order of magnitude larger than the nematic flexoelectric constant.