Abstract
Optical microscopic and ellipsometric studies of the spreading of a mesogenic compound on a rough substrate are reported on. The smectic wets the surface and a precursor film grows whose radius R scales like the square root of time t: R ≈ (Dt)1/2. The diffusion coefficient decreases with temperature and vanishes several degrees below the melting temperature, i.e. the solid phase also "spreads out" through a precursor film. The effect is analysed in terms of surface-induced premelting. This is the first report on such an effect in mesogenic materials.