Deuterium NMR spectroscopy and field-induced director dynamics in liquid crystals

Deuterium NMR spectroscopy together with spectral simulations have been used to investigate the field-induced director dynamics in a nematic liquid crystal, 4-pentyl-4'-cyanobiphenyl (5CB), conned in a slab between two electrodes. The NMR spectra have been measured when turning the electric field on and turning it off. Measurements were also made at different temperatures to explore how the temperature effects the director relaxation. At higher temperatures, some complications arise as peculiar oscillations are observed in the spectra. With spectral simulation this phenomena is shown to result from the relaxation of the director on a timescale comparable to that of the experiment which is the effective spin-spin relaxation time. The simulated spectra are compared with the experimental spectra for the specifically deuteriated 5CB-d(2).