A deuterium nuclear magnetic resonance investigation of field induced director dynamics in a nematic slab subject to magnetic and pulsed electric fields

Deuterium nuclear magnetic resonance (NMR) spectroscopy has been used to in vestigate the field-induced director dynamics in a nematic liquid crystal, 4-pentyl-d(2)-4'-cyanobiphenyl (5CB-d(2)) deuteriated in the alpha -positio n of the pentyl chain, confined between two glass plates. The NMR spectra h ave been measured as a function of time after turning an electric field on and off It is demonstrated that the field-induced director dynamics in the nematic liquid crystal cells can be successfully time-resolved. In addition , it is found that the doubler NMR spectra become powder-like during the tu rn-on and rum-off processes. It is shown that the rotational viscosity and the diamagnetic anisotropy of 5CB-d(2) can be determined from the time-reso lved NMR spectra by assuming uniform alignment of the director.