LIFETIME OF UNDERCOOLED WETTING LAYERS

The recently observed large hysteresis effects in undercooling or overheating of wetting layers in systems with a prewetting transition are shown to be a simple consequence of the geometry of the phase diagram. In order to estimate quantitatively the lifetime of such metastable layers, one has to calculate the excess free energy E(c) of the corresponding critical nuclei. For the case of undercooling we determine E(c) as a function of chemical potential mu for a fixed temperature T well below the wetting transition point T-w. For overheating E(c) is known from previous calculations as a function of T at bulk coexistence mu = mu(c).