Fig. 4.

(A–C) Enthalpy $\left(\mathrm{\Delta }{H}_{\mathrm{a}}\right)$ and entropy $\left(-T\mathrm{\Delta }{S}_{\mathrm{a}}\right)$ contributions to the free energy of association ($\mathrm{\Delta }{W}_{\mathrm{a}}$, as defined by Eq. 1) for (A) $M^{+}-M^{-}$, (B) $M^{+}-M^{+}$, and (C) $M^{-}-M^{-}$ ion pairs at various z locations. Inset in A focuses on the z locations that are on the liquid side of the interface.