Light scattering processes in nematic liquid crystals without alignment control

Light scattering processes in unconfined nematic liquid crystals have been investigated by means of time-resolved transmittance and static light scattering techniques. In time-resolved experiments, sample temperature has been modulated and different modalities of propagation have been probed. The results here obtained show that a nematic polydomain liquid crystal exhibits scattering properties strongly different from a nematic monodomain and, in a sense, it behaves as an optically thin sample. Such a behaviour may be ascribed to the strong backscattering exhibited by the polydomain sample, as indicated by static light scattering experiments, where the angular dependence of the scattered intensity was measured, revealing a preferential backward direction. The two experimental techniques here adopted have shown their complementary role to understand the actual scattering regime. The diffusion constant D has been determined by means of time-resolved measurements and a comparison with the results obtained in monodomain nematic liquid crystals has been attempted.