Measurements of dc Kerr Constants for a Homologous Series of Nematic Compounds

The dc Kerr constants of seven p,p′-n-alkoxyazoxybenzene homologous compounds have been measured as functions of temperature in the isotropic phase. The observed pretransitional behavior near the isotropic-nematic transition is consistent with the phenomenological model of Landau-de Gennes with the Onsager's loal-field correction included in the dielectric tensor. The dc polarizability anisotropy and the average orientation of the permanent dipole with respect to the long molecular axis are deduced from the experimental results. Their variations with increase of methylene groups in the alkyl chains are discussed.