Liquid nucleation around charged particles in the vapor phase

TL;DR

This paper develops a theoretical model for liquid droplet nucleation around charged particles in vapor, accounting for nonuniform phases, electrostatic effects, and phase transitions, expanding beyond classical nucleation theory.

Contribution

It introduces a comprehensive theory incorporating electrostatics and nonuniform phases to analyze nucleation near charged particles, including phase diagrams and transition points.

Findings

Charge destabilizes vapor near critical point, promoting nucleation.

Adsorption exhibits discontinuous and divergent behavior at phase transitions.

Field gradients extend the conditions under which liquid nucleation occurs.

Abstract

We theoretically investigate the nucleation of liquid droplets from vapor in the presence of a charged spherical particle. Due to field gradients, sufficiently close to the critical point of the vapor--gas system, the charge destabilizes the vapor phase and initiates a phase transition. The fluid's free energy is described by the van der Waals expression augmented by electrostatic energy and a square-gradient term. We calculate the equilibrium density profile at arbitrary temperatures, particle charges, and vapor densities. In contrast to classical nucleation theory, here, both liquid and vapor phases are different from the bulk phases because they are spatially nonuniform. In addition, the theory applies to both sharp and diffuse interfaces and calculates the surface tension self-consistently. We find the composition profiles and integrate them to get the adsorption near the particle. We find that the adsorption changes discontinuously at a first-order phase transition line. This line becomes a second-order phase transition at high enough temperatures. We describe the transition point numerically and provide approximate analytical expressions for it. Similarly to prewetting, the adsorption diverges at the binodal phase boundary. We construct a phase diagram indicating changes in the binodal, spinodal, and critical temperature. It is shown that the field gradient enlarges the range of temperature and vapor density where liquid can nucleate.