Molecular reorientations in liquid crystal 6O.4

Quasielastic neutron scattering (QENS) studies on the reorientational dynamics in the ordered phases (crystalline and the smectic H) of p-n-hexyloxybenzylidine-p′-n-butylaniline (6O.4) are reported here. Analysis of the QENS data showed that in the crystalline phase (room temperature ∼25 °C) the reorientational motion involves only the core of the molecule, whereas in the SH phase (at 45 °C) the whole molecule is involved. This motion is found to persist even when the sample was cooled back to 25 °C (below the crystalline–SH transition temperature of 33.7 °C) suggesting existence of the liquid crystalline phase as a supercooled state. DSC measurements and X-ray diffraction studies corroborate the QENS results.