A study was made of the diffusion and sub-monolayer spreading of chain-like molecules. By using the fluctuating bond model, the collective and tracer diffusion coefficients were deduced. It was shown that the diffusivity exhibited an unusual coverage dependence. It first increased with coverage, to a maximum, and then tended to zero as the coverage approached unity. The increase was attributed to an entropic repulsion that led to steep density profiles for spreading droplets, as observed experimentally.

T.Ala-Nissila, J.S.Herminghaus, T.Hjelt, P.Leiderer: Physical Review Letters, 1996, 76[21], 4003-6