title: Atomically resolved three-dimensional structures of electrolyte aqueous solutions near a solid surface.
abstract: Interfacial liquid layers play a central role in a variety of phenomena ranging from friction to molecular recognition. Liquids near a solid surface form an interfacial layer where the molecular structure is different from that of the bulk. Here we report atomic resolution three-dimensional images of electrolyte solutions near a mica surface that demonstrate the existence of three types of interfacial structures. At low concentrations (0.01-1 M), cations are adsorbed onto the mica. The cation layer is topped by a few hydration layers. At higher concentrations, the interfacial layer extends several nanometres into the liquid. It involves the alternation of cation and anion planes. Fluid Density Functional calculations show that water molecules are a critical factor for stabilizing the structure of the interfacial layer. The interfacial layer stabilizes a crystal-like structure compatible with liquid-like ion and solvent mobilities. At saturation, some ions precipitate and small crystals are formed on the mica.
authors.affiliation: Instituto de Ciencia de Materiales de Madrid, CSIC, c/ Sor Juana Ines de la Cruz 3, 28049 Madrid, Spain.
authors.forename: Daniel
authors.initials: D
authors.lastname: Martin-Jimenez
authors.affiliation: Instituto de Ciencia de Materiales de Madrid, CSIC, c/ Sor Juana Ines de la Cruz 3, 28049 Madrid, Spain.
authors.forename: Enrique
authors.initials: E
authors.lastname: Chacon
authors.affiliation: Department Física Teórica de la Materia Condensada, IFIMAC Condensed Matter Physics Center, UAM, 28049 Madrid, Spain.
authors.forename: Pedro
authors.initials: P
authors.lastname: Tarazona
authors.affiliation: Instituto de Ciencia de Materiales de Madrid, CSIC, c/ Sor Juana Ines de la Cruz 3, 28049 Madrid, Spain.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Garcia