Inversion of self-diffusion anisotropy by chemical substitution in smectic A liquid crystals as evidenced by PGSE experiment combined with a quadrupole-coil rotation.

A technique of pulsed-field-gradient spin-echo (PGSE) NMR combined with a quadrupole-coil rotation was applied to the study of anisotropic self-diffusion in smectic A liquid crystals. Diffusion anisotropy was found to be inverted by chemical substitution of the terminal groups in homologous compounds: Namely, the diffusion across the layer is faster for the cyano compound, whereas the diffusion within the layer is faster for the trifluoromethoxy compound.