The modified Thomson equation in the theory of heterogeneous vapor nucleation on charged solid particles

Abstract

Thermodynamic theory of heterogeneous vapor nucleation on charged nanosized solid particles is considered and formulas for the condensate chemical potential in the droplet and the nucleation activation barrier are derived. A modified Thomson equation for the pressure of vapor saturated over a liquid droplet formed around the spherical charged particle is proposed. This equation determines the saturated vapor pressure as a function of the particle size, charge magnitude and sign, and the droplet radius. The approach assumes that the droplet liquid film between the particle and the vapor phase is polarized in the central electric field of the charged particle and is thin, i.e., surface layers of the film at the boundaries with the particle and the vapor phase are overlapped and the arising disjoining pressure affects the droplet state. It is shown that the film disjoining pressure, the Maxwell stress of the film in the central electric field of the particle, the degree of the particle wetting, and the particle size interplay in determination of the threshold value of vapor supersaturation ratio at barrierless nucleation. The threshold values of the vapor supersaturation ratio were found for different model isotherms of the disjoining pressure and different relations between size and charge of the solid particles.