Dressed Counterions: Poly- and monovalent ions at charged dielectric interfaces

TL;DR

This paper develops an effective 'dressed counterion' approach to analyze ion distributions and overcharging at charged dielectric interfaces with asymmetric electrolytes, validated by simulations and applicable in strong-coupling regimes.

Contribution

It introduces a novel analytical framework combining dressed counterions with strong-coupling theory for polyvalent ions at low concentrations.

Findings

The dressed counterion approach agrees with Monte-Carlo simulations.

The strong-coupling theory describes salt effects and dielectric inhomogeneities.

Limitations of the theory are systematically examined.

Abstract

We investigate the ion distribution and overcharging at charged interfaces with dielectric inhomogeneities in the presence of asymmetric electrolytes containing polyvalent and monovalent ions. We formulate an effective "dressed counterion" approach by integrating out the monovalent salt degrees of freedom and show that it agrees with results of explicit Monte-Carlo simulations. We then apply the dressed counterion approach within the framework of the strong-coupling theory, valid for polyvalent ions at low concentrations, which enables an analytical description for salt effects as well as dielectric inhomogeneities in the limit of strong Coulomb interactions on a systematic level. Limitations and applicability of this theory are examined by comparing the results with simulations.