title: Oversolubility in the microvicinity of solid-solution interfaces.
abstract: Water-solid interactions at the macroscopic level (beyond tens of nanometers) are often viewed as the coexistence of two bulk phases with a sharp interface in many areas spanning from biology to (geo)chemistry and various technological fields (membranes, microfluidics, coatings, etc.). Here we present experimental evidence indicating that such a view may be a significant oversimplification. High-resolution infrared and Raman experiments were performed in a 60 × 20 μm(2) quartz cavity, synthetically created and initially filled with demineralized water. The IR mapping (3 × 3 μm(2) beam size) performed using the SOLEIL synchrotron radiation source displays two important features: (i) the presence of a dangling free-OH component, a signature of hydrophobic inner walls; (ii) a shift of the OH-stretching band which essentially makes the 3200 cm(-1) sub-band predominate over the usual main component at around 3400 cm(-1). Raman maps confirmed these signatures (though less marked than IR's) and afforded a refined spatial distribution of this interfacial signal. This spatial resolution, statistically treated, results in a puzzling image of a 1-3 μm thick marked-liquid layer along the entire liquid-solid interface. The common view is then challenged by this strong evidence that a μm-thick layer analogous to an interphase forms at the solid-liquid interface. The thermodynamic counterpart of the vibrational shifts amounts to around +1 kJ mol(-1) at the interface with a rapidly decreasing signature towards the cavity centre, meaning that vicinal water may form a reactive layer, of micrometer thickness, expected to have an elevated melting point, a depressed boiling temperature, and enhanced solvent properties.
authors.affiliation: Institut des Sciences de la Terre d'Orléans, UMR 7327 Université d'Orléans/CNRS/BRGM, 45071 Orléans Cedex, France. lionel.mercury@univ-orleans.fr.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Bergonzi
authors.affiliation: Institut des Sciences de la Terre d'Orléans, UMR 7327 Université d'Orléans/CNRS/BRGM, 45071 Orléans Cedex, France. lionel.mercury@univ-orleans.fr.
authors.forename: Lionel
authors.initials: L
authors.lastname: Mercury
authors.affiliation: CNRS, CEMHTI UPR3079, Université d'Orléans, CS 90055, 45071 Orleans Cedex 2, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Simon
authors.affiliation: Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin, BP 489, 91192 Gif-sur-Yvette, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Jamme
authors.affiliation: Institute of Experimental Mineralogy, Russian Academy of Science, 142432 Chernogolovka, Russia.
authors.forename: Kirill
authors.initials: K
authors.lastname: Shmulovich