Temperature variation of transverse correlation length in the smectic C and nematic phases of a liquid crystal from X-ray and neutron diffraction studies

The transverse correlation length, xi, in the nematic and smectic C phases of heptyloxyazoxy-benzene (HAB) have been determined from neutron scatterin g and x-ray diffraction techniques. The experimental intensity values I(q) are fitted using least squares method to a Lorenztian function. The xi valu es diverges near the smectic C to nematic transition indicating second orde r phase transition. The intermolecular distance throughout the mesomorphic range has also been determined.