Interfacial premelting and the thermomolecular force: Thermodynamic buoyancy - art. no. 088501

The presence of a substrate can alter the equilibrium state of another mate rial near their common boundary. Examples include wetting and interfacial p remelting. In the latter case, temperature gradients induce spatial variati ons in the thickness of the premelted film that reflect changes in the stre ngth of the repulsion between the substrate and the solid. We show that the net thermomolecular force on a macroscopic substrate is equivalent to a th ermodynamic buoyancy force-proportional to the mass of solid that can occup y the volume enclosed by the substrate and the temperature gradient.