Abstract
The phason dispersion in the antiferroelectric SmCA * liquid crystalline phase of 4-(1-methylheptyl-oxycarbonyl) phenyl 4′-octyloxybiphenyl-4-carboxylate has been studied by time-resolved quasielastic light scattering spectroscopy. The phason branch is found to be gapless as predicted for a Goldstone mode recovering the broken continuous symmetry. The dispersion has a minimum at q = 2qc , where qc is the wave-vector of the helicoidal SmCA * phase. The results are consistent with the alternating-tilt model of antiferroelectric liquid crystals and the first order approximation to the optìcal properties of birefringent and modulated superstructures.
Key Words: