Phys. Rev. Lett.

Detection of Phase Biaxiality in Liquid Crystals by Use of the Quadrupole Shift in ^{131} Xe NMR Spectra

from Recent Articles in Phys. Rev. Lett. by Jukka P. Jokisaari, Anu M. Kantola, Juhani A. Lounila, and L. Petri Ingman

An experimental method to unambiguously distinguish between uniaxial and biaxial liquid crystal phases is introduced. The method is based on the second order quadrupole shift (SOQS) observable in ¹³¹Xe NMR spectra of xenon dissolved in liquid crystals. It is shown that besides revealing the biaxiality, the ¹³¹Xe SOQS offers a novel method to determine the tilt angle in smectic C phases. As an example, the ¹³¹Xe SOQS in a ferroelectric liquid crystal is reported. It yields up a biaxial phase in between isotropic and smectic C phases.