Chapter 19 - Line energy

Abstract

This chapter illustrates how line energy can influence the kinetics of 3D heterogeneous nucleation (HEN) of cap-shaped nuclei of condensed phases. The energy balance for a system in which three or more phases contact along a line requires accounting for the energy arising from the presence of the contact line. The classical theory of 3D HEN of cap- or lens-shaped nuclei, however, ignores the contribution of the line energy, although the periphery of the cap or the lens represents a line of three-phase contact. Line energy effects of the kind considered in the chapter may be expected to be of significance also for 3D HEN of cap-shaped bubbles provided the radius R* of the nucleus bubble is sufficiently small. A cap-shaped cluster of radius R and wetting angle θw in the range from complete wetting (θw = 0) to complete non-wetting (θw = π). In principle, R and θw can be treated as independent variables, but for a given cluster volume their values are most likely to be those corresponding to the equilibrium shape of the cluster.