Liquid flow in wetting layers on rough substrates

We investigate experimentally the lateral ow in thin liquid adsorbate lms o n substrates with variable roughness. We nd that, as a consequence of nanos cale roughness, the ability of the lms to equilibrate lateral fluctuations depends remarkably weakly on lm thickness. Our results suggest that it is a quite general feature of adsorbate lms on real surfaces. This is of substa ntial importance for all systems in which transport in adsorbed layers play s a role.