We present a Ginzburg-Landau theory of ion-induced nucleation in a gas phase of polar one-component fluids, where a liquid droplet grows with an ion at its center. By calculating the density profile around an ion, we show that the solvation free energy is larger in gas than in liquid at the same temperature on the coexistence curve. This difference much reduces the nucleation barrier in a metastable gas.
REFERENCES
The free energy due to the polarization and the charge12 is with . For we obtain Eqs. (2.1) and (2.5). If , it is equal to the vacuum result for a single ion. If without electrostriction, it is equal to in Eq. (2.17). In literature (Refs. 5 and 10) the difference of these two quantities is the Born formula for the solvation free energy.
In discussing the droplet growth we need to consider the inhomogeneity of the temperature induced by latent heat absorption or generation at the interface (Ref. 21).
In dynamics growing or shrinking of the droplet occurs depending on whether the added particle number is positive or negative. For example, this can be verified if we assume the time-evolution equation .
Near the critical point we obtain , where is the correlation length with and being the critical exponents (Ref. 21). The interface thickness is of the order .