Orientational diffusivities measurement by light-beating spectroscopy for a disk-like thermotropic nematic phase (ND)

Using a light-beating technique and for an appropriate scattering geometry, we have measured separately the orientational diffusivities D_splay and D_twist for an 'hexa-n-alcanoyloxytruxene' (HATX C₁₂H₂₅) sample which exhibits a disk-like thermotropic nematic phase (N_D) between 57°C and 84°C. D_splay and D_twist are about 100 times weaker than those corresponding to rod-like thermotropic nematics. The deviation can be attributed to higher viscosities η_splay and η_twist.