title: A relationship between three-dimensional surface hydration structures and force distribution measured by atomic force microscopy.
abstract: Hydration plays important roles in various solid-liquid interfacial phenomena. Very recently, three-dimensional scanning force microscopy (3D-SFM) has been proposed as a tool to visualise solvated surfaces and their hydration structures with lateral and vertical (sub) molecular resolution. However, the relationship between the 3D force map obtained and the equilibrium water density, ρ(r), distribution above the surface remains an open question. Here, we investigate this relationship at an interface of an inorganic mineral, fluorite, and water. The force maps measured in pure water are directly compared to force maps generated using the solvent tip approximation (STA) model and from explicit molecular dynamics simulations. The results show that the simulated STA force map describes the major features of the experimentally obtained force image. The agreement between the STA data and the experiment establishes the correspondence between the water density used as an input to the STA model and the experimental hydration structure and thus provides a tool to bridge the experimental force data and atomistic solvation structures. Further applications of this method should improve the accuracy and reliability of both interpretation of 3D-SFM force maps and atomistic simulations in a wide range of solid-liquid interfacial phenomena.
authors.affiliation: Division of Electrical Engineering and Computer Science, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan. fukuma@staff.kanazawa-u.ac.jp.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Miyazawa
authors.affiliation: Division of Electrical Engineering and Computer Science, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan. fukuma@staff.kanazawa-u.ac.jp.
authors.forename: Naritaka
authors.initials: N
authors.lastname: Kobayashi
authors.affiliation: School of Mathematics and Physics, University of Lincoln, Brayford Pool, Lincoln LN6 7TS, UK.
authors.forename: Matthew
authors.initials: M
authors.lastname: Watkins
authors.affiliation: Department of Physics and Astronomy and London Centre for Nanotechnology, University College London, Gower Street, London, WC1E 6BT, UK.
authors.forename: Alexander L
authors.initials: AL
authors.lastname: Shluger
authors.affiliation: Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan.
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Amano
authors.affiliation: Division of Electrical Engineering and Computer Science, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan. fukuma@staff.kanazawa-u.ac.jp and ACT-C, Japan Science and Technology Agency, Honcho 4-1-9, Kawaguchi 332-0012, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Fukuma