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Free keywords:
deuterium NMR; director dynamics; liquid crystal; 9CB
Abstract:
Deuterium NMR spectroscopy has been used to investigate the director dynamics of deuteriated 4-α,α-d2-nonyl-4′-cyanobiphenyl, where the director was aligned by an electric field. The electric field direction made an angle of 47° with the magnetic field in order to provide a unique alignment pathway; accordingly the director is expected to rotate as a monodomain. The time dependence of the director orientation was investigated at different temperatures. At each temperature in the nematic phase, all of the deuterium NMR spectra indicate that the director was uniformly oriented as a monodomain. It was found that the relaxation time in the smectic A phase is about 1,000,000 times as large as that in the nematic phase. This also results in a strong pretransitional growth of the relaxation time as the transition to the smectic A phase is approached.
