Ordering in the nematic mesophase of a rapidly spinning sample

Abstract

Abstract The high resolution 13 C NMR spectrum of an eutectic mixture of N‐(p ‐methoxybenzylidene)‐ p‐n ‐butylaniline and N‐(p ‐ethoxybenzylidene)‐ p‐n ‐butylaniline has been measured as a function of the spinning angle θ between the rotor axis and the magnetic field. The influence of a strong magnetic field and rapid sample spinning gives rise to a specific orientation of this nematic mesophase; if 0 < θ < 54°44′; the director of the nematic phase is oriented in parallel with the rotor axis, and if 54°44′; < θ <90° it is perpendicular to the rotor axis. At the exact magic angle a nematic sample displays the chemical shifts of the corresponding isotropic liquid. Nematic order is retained at all other director‐field angle values, thus allowing chemical shift anisotropy measurements of the nematic sample or of compounds dissolved therein.