Electrostatic interactions at interfaces depend upon the distribution of ions near the interface.  We investigate this distribution by x-ray reflectivity and interfacial tension measurements of the electrified liquid/liquid interface between organic and aqueous electrolyte solutions.  The x-ray reflectivity measurements probe the voltage-controlled variation of the electrolyte concentration with sub-nanometer spatial resolution and the interfacial tension measurements are used to determine the variation of the interfacial excess charge with voltage.  Data analysis relies upon a density functional approach to include ion-solvent interactions and ion-ion correlations in the predictions for the ion distributions.  This analysis is consistent with the tension data without any free parameters.  Similarly, only one adjustable parameter, which accounts for thermal fluctuations of the interface, is required to explain the x-ray data.

Effect of ion correlations and ion-solvent interactions on ion distributions at interfaces

244th National Meeting (2012)

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