The surface-induced static director distribution in thin nematic liquid crystal films: A deuterium nuclear magnetic resonance spectroscopy study

Luckhurst, G. R., Miyamoto, T., Sugimura, A., Takashiro, T. and Timimi, B. A. (2001) The surface-induced static director distribution in thin nematic liquid crystal films: A deuterium nuclear magnetic resonance spectroscopy study. The Journal of Chemical Physics, 114 (23), 10493-10503. (doi:10.1063/1.1373647).

Abstract

We have studied the static director distribution in thin nematic liquid crystal cells with different film thicknesses and different surface anchoring strengths using a combination of deuterium nuclear magnetic resonance (NMR) spectroscopy and continuum theory. A nematic liquid crystal, 4-pentyl-d(2)-4'-cyanobiphenyl (5CB-d(2)) deuteriated in the ct position of:the pentyl chain, was confined between two glass plates with both weak and strong anchoring conditions; the anchoring strengths were measured by using a saturation voltage method. A series of deuterium NMR spectra, obtained using a quadrupolar echo sequence, was acquired as a function of the applied electric field, which can be used to explore the:director deformation. The deuterium NMR spectra predicted by continuum theory involving the magnetic, electric, elastic, and unified surface anchoring energies are found to be in good agreement with experiment. The investigation also reveals that profiles of the director distribution for the case with a magnetic field have a top-hat shape different to the bowler-hat shape, which is well known as the director profile for the case with no magnetic field.

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