CRITICAL NUCLEI FOR WETTING AND DEWETTING

In a first-order wetting transition it is possible to overheat a micro scopic layer from below to above the wetting temperature T(w), and to undercool a macroscopic layer from above to below T(w). in both cases the transition to stable equilibrium occurs by formation and growth of supercritical nuclei. The critical nuclei for overheating are droplet s on the wall of the system and for undercooling they are dents in the macroscopic layer. A recent calculation of the critical droplet in a special dimension d0 is now supplemented by the calculation of the cri tical dent for dewetting. Although the analytic expressions for the pr ofiles are closely related, the nuclei above T(w) are finite whereas t hey are infinitely large below T(w). The latter is to be expected sinc e the system is infinitesimally close to coexistence of wet and non-we t states at all temperatures T< T(w).