Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, Vol.366, 1889-1894, 2001
NMR study of the local molecular dynamics in the isotropic phase of a thermotropic liquid crystal
Nuclear Magnetic Resonance proton spin-lattice measurements in phentylcyano-phenylcyclohexane liquid crystal at the Larmor frequencies 1.235 MHz and 48 kHz in a temperature range above the nematic-isotropic phase transition are reported. The Landau-De Gennes theory for nematic-isotropic phase transition is used to analize the temperature dependence of the spin-lattice correlation functions. We conclude that the low frequency approximation can be applied only when the experiment is carried out at Larmor frequencies in the kHz range.