Effects of Order and Fluctuations on theN14NMR in a Liquid Crystal

Abstract

The ${\mathrm{N}}^{14}$ NMR spectrum in the nematic phase and linewidth in the isotropic phase of para-azoxyanisole (PAA) are reported. The linewidth $\Delta$ in the isotropic phase follows the relation ${\Delta }^{\propto }{(T-T^{*})}^{\frac{1}{2}}$, where $T^{*}$ is a temperature slightly below the nematic-isotropic transition. This result is interpreted in terms of the local order fluctuations expected in the vicinity of a weakly first-order transition.