Nuclear spin relaxation in nematic liquid crystals

Academic Article

Abstract

  • Studies of proton spin-lattice relaxation as a function of temperature are reported for the following liquid crystals: p-azoxyanisole (I), butyl p-(p-ethoxyphenoxycarbonyl)phenyl carbonate (II), p-(p-ethoxyphenylazo)phenyl hexanoate (III), p-(p-ethoxyphenylazo)phenyl undecylenate (IV), and p-[N-(p-methoxybenzylidene)amino]-n-butylbenzene (V). Compound V has also been studied with an electric field of strength ∼5 kV/cm perpendicular to the applied magnetic field. Order parameters (S) and second moments obtained from wide line spectra are displayed for compounds II-V. It is found that T 1 increases with increasing temperature immediately above the melting point for compounds I-V and that T 1 does not depend on the alignment of the major molecular axis with respect to the magnetic field for compound V. These results suggest that spin relaxation in the nematic phase is determined by translational diffusion. The frequency dependence of T 1 probably does not distinguish between rotational and translational contributions to spin relaxation.
  • Author List

  • Watkins CL; Johnson CS
  • Start Page

  • 2452
  • End Page

  • 2458
  • Volume

  • 75
  • Issue

  • 16