Abstract
The orientational order parameters have been measured by deuteron N.M.R. of both solute (at low dilution) and solvent in various binary mixtures involving the liquid crystal 4,4′-di-n-heptylazoxybenzene (HAB). The solutes studied were azoxybenzene-d10 and n-heptylbenzene-d7 which are fragments of HAB, azobenzene-d 10 because of its similarity to azoxybenzene, and anthracene-d10 because of its known structure and symmetric shape. The major and biaxial order parameters of the solutes are analysed in terms of a molecular field model for the potential of mean torque for biaxial particles. The behaviour of the solute order parameters on approaching and entering the smectic A phase is interpreted in terms of a temperature and phase dependent partitioning of the solute between aromatic and aliphatic regions of the solvent.