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O: Fachverband Oberflächenphysik

O 18: Solid-liquid Interfaces II

O 18.4: Vortrag

Montag, 31. März 2014, 16:45–17:00, WIL A317

Microscopic characterization of the CaF2 / water interfaces. — •Rémi Khatib¹, Maria J. Perrez-Haro², Mischa Bonn², Ellen H.G. Backus², and Marialore Sulpizi¹ — ¹Johannes-Gutenberg University, Mainz, Germany — ²Max Planck Institute for polymer research, Mainz, Germany

From biological membranes to heterogeneous catalysis through atmospheric chemistry, interfaces involving liquid water are common on Earth. Vibrational Sum Frequency Generation (SFG) is a spectroscopic technique which allow a selective characterization of interfacial water. In order to rationalize the experimental results obtained for CaF2 / water interfaces, a theoretical approach has been used, based on first principles molecular dynamics simulations.

In particular Born-Oppenheimer Molecular Dynamics (BOMD) have been used on different model systems to describe a wide range of pH of the aqueous solution. Different tools, like the Velocity Density of States (VDOS), Radial Distribution Function (RDF), were employed to analyze the data. The preliminary results are promising: a *free OH* peak measured by SFG under basic conditions can certainly be explained by a substitution of F- by HO- at the interface. Moreover a microscopic characterization of the water species and dynamics at low pH is also provided.