Surface diffusion of matter in discotic liquid crystal threads

The first measurements of the surface diffusion coefficients in columnar discotic liquid crystal thread and film by an optical absorption technique are presented. A comparison of the results with the diffusion in the bulk specimen helps to introduce the number of diffusion sites in the surface and in the bulk. We propose then a structure of point defects in the mesophase. An estimation of jump frequency is deduced. The dependence of the surface diffusion versus the temperature seems in agreement with the Arrhenius law.