Collective and molecular motions of fluorinated liquid crystals by means of F-19 Fast Field-Cycling NMR relaxometry

F-19 Fast Field-Cycling (FFC) NMR relaxometry was applied for the first time for the investigation of the dynamics of a liquid crystal. Longitudinal F-19 relaxation rates were measured at different temperatures in the nematic phase of 4DBF2 in the frequency range between about 9.5 kHz and 33 MHz. The observed relaxation dispersions could be well reproduced using a simple model in which contributions due to order director fluctuations and molecular rotational diffusion motions were considered. The obtained results indicate F-19 FFC NMR relaxometry as a valuable method for the investigation of molecular and collective motions of fluorinated liquid crystals.