title: Water-induced correlation between single ions imaged at the solid-liquid interface.
abstract: When immersed into water, most solids develop a surface charge, which is neutralized by an accumulation of dissolved counterions at the interface. Although the density distribution of counterions perpendicular to the interface obeys well-established theories, little is known about counterions' lateral organization at the surface of the solid. Here we show, by using atomic force microscopy and computer simulations, that single hydrated metal ions can spontaneously form ordered structures at the surface of homogeneous solids in aqueous solutions. The structures are laterally stabilized only by water molecules with no need for specific interactions between the surface and the ions. The mechanism, studied here for several systems, is controlled by the hydration landscape of both the surface and the adsorbed ions. The existence of discrete ion domains could play an important role in interfacial phenomena such as charge transfer, crystal growth, nanoscale self-assembly and colloidal stability.
authors.affiliation: Department of Materials Science and Engineering, Ecole Polytechnique Fédérale de Lausanne, (EPFL), 1015 Lausanne, Switzerland.
authors.forename: Maria
authors.initials: M
authors.lastname: Ricci
authors.affiliation: Department of Applied Physics, COMP Centre of Excellence, Aalto University, P.O. Box 11100, FI-00076 Helsinki, Finland.
authors.forename: Peter
authors.initials: P
authors.lastname: Spijker
authors.affiliation: 1] Department of Materials Science and Engineering, Ecole Polytechnique Fédérale de Lausanne, (EPFL), 1015 Lausanne, Switzerland [2] Department of Physics, Durham University, South Road, Durham DH1 3LE, UK.
authors.forename: Kislon
authors.initials: K
authors.lastname: Voïtchovsky