Hydration forces near charged interfaces in terms of effective ion potentials

Experiments and simulations provide detailed information on the structure and interaction of charged interfaces in aqueous solutions. In order to understand this information in terms of general principles it is favourable to use effective potentials, which describe the interaction of ions and surfaces in the presence of solvent. Effective potentials are derived from molecular simulations and are capable of discerning ion-specific behaviour. We argue that short-range interactions in aqueous solutions involve two characteristic lengths, the range of the interaction and the spatial periodicity, both about 2.5 ± 0.5 إ.