DECAY OF METASTABLE STATES IN WETTING AND DEWETTING TRANSITIONS

In a first-order wetting transition metastable surface states can be p roduced by overheating a nonwet wall or by undercooling a wetting laye r covering the wall. These metastable states decay via the formation a nd subsequent growth of supercritical nuclei. The size and excess free energy of the critical nuclei diverge when some internal point on the line of phase transitions between wet and nonwet states is approached . For the case of overheating the critical nuclei are droplets on the wall, whereas for undercooling they are dents in the wetting layer. Th e critical droplets show a very different behaviour in the partial-wet ting, complete-wetting and prewetting regimes. It is shown that the cr itical dents also differ significantly from each other in three regime s of the phase diagram which we denote by the partial-dewetting, dewet ting and pre-dewetting regimes.