Transverse surface-induced polarization at the interface between a chiral nematic liquid crystal and a substrate

A chiral nematic liquid crystal that is tilted by an angle ${\theta }_i$ with respect to a substrate is subjected to an ac electric field at frequency $\omega$ applied parallel to the substrate. The nematic director is found to oscillate azimuthally about the normal to the liquid crystal–substrate interface at frequency $\omega ,$ indicating that a nonzero polarization perpendicular to the molecular tilt plane exists at the interface. The interfacial polarization, anchoring strength coefficient, and bulk viscosity are obtained by measurements of the oscillation amplitude as a function of $\omega .$