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 (ND) 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 ηsplay and ηtwist.