Anisotropy of Self-Diffusion in the Smectic-Aand Smectic-CPhases

The anisotropy of the translational self-diffusion tensor in the smectic-$A$ ($\frac{〈D_{\parallel }〉}{〈D_{\perp }〉}=0.3\mathrm{}$) and smectic-$C$ phases of terephthal-bis-4-$n$-butylaniline has been determined by multipulse NMR. The experimental results are interpreted in terms of a pseudolattice model with anisotropic potential barriers which seems to provide a better description of the physical situation than the "two-dimensional-liquid" model.