ABSTRACT
An “interface” is, as the name suggests, a boundary between phases. Because interfaces are very thin-in most cases only a few molecular diameters thickwe sometimes tend to think of them as two-dimensional surfaces and neglect their thicknesses. But the third dimension is of great significance as well. Indeed, the rapid changes in density and composition across interfaces give them their most important property, an excess free energy or lateral stress which is usually called interfacial tension.
