Planar Diffusion, Discrete Jumps and Restricted Diffusion in Columnar Mesophases
Deuterium NMR of two homologous series of pyramidic liquid crystals exhibiting columnar mesophases is reported. It is shown that within the mesophase region, molecular reorientation about the columnar axes occurs according to two distinct mechanisms, i.e. planar diffusion and discrete three-fold jumps. A general formalism is presented for restricted molecular diffusion in a symmetric three-fold potential with the above mechanisms corresponding to the zero- and infinite-potential ends of the model.