Photon correlation spectroscopy of confined liquid crystals in isotropic, nematic, and smectic phases

Photon correlation experiments were performed to study the influence of confinement on the dynamic behavior of liquid crystals (LCs) in isotropic, nematic and smectic-A phases. In isotropic phase the only fast, single exponential decay due to the order parameter fluctuations is observed. While decreasing the temperature, but still above I-N phase transition in pores, the contribution from this decay decreases and second decay due to director fluctuations appears. The existence of this decay is the evidence for the formation of ordered (paranematic) phase preceding I-N transition in confined LCs. In nematic phase the decay due to order parameter fluctuations vanishes, the relaxation due to director fluctuations dominates, and slow process absent in the bulk LC appears. In smectic phase the director fluctuations are almost frozen.