title: Shared solvation of sodium ions in alcohol-water solutions explains the non-ideality of free energy of solvation.
abstract: In order to explain the discrepancies between theories and experiments regarding the non-ideality in the free energy of solvation, here we present a microscopic picture of sodium ions dissolved in water-alcohol mixed solvents. We used X-ray absorption spectroscopy to probe the K-edge of sodium ions in mixed solvents of water and alcohols (methanol, ethanol) and in the respective pure solvents. In the mixed solvents a shared solvation of the sodium ions is observed. We find that specifically the water component plays a key role in stabilizing the solvation shell in mixed solvents, which was revealed by a selective photochemical process occurring only in the pure alcohol solvents.
authors.affiliation: Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein Str. 15, 12489 Berlin, Germany.
authors.forename: Kathrin M
authors.initials: KM
authors.lastname: Lange
authors.forename: Ulf
authors.initials: U
authors.lastname: Bergmann
authors.forename: Kai F
authors.initials: KF
authors.lastname: Hodeck
authors.forename: René
authors.initials: R
authors.lastname: Könnecke
authors.forename: Ulrich
authors.initials: U
authors.lastname: Schade
authors.forename: Emad F
authors.initials: EF
authors.lastname: Aziz