The determination of translational diffusion constants in liquid crystals from pulsed field gradient double quantum spin echo decays

Abstract

Proton double quantum decay rates in presence of pulsed magnetic field gradients have been used to measure translational diffusion coefficients. The method is superior to analogous techniques based on single quantum echoes because double quantum coherence experiences effectively twice the applied field gradient. In cases where the natural double quantum decay rate is less than that of single quantum coherence, further increases in precision can be realized. The method is illustrated by measurements of solute diffusion parallel and perpendicular to the director axis in nematic and smectic liquids crystalline media.