Dresden 2011 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 12: Posters: New Technologies
BP 12.10: Poster
Montag, 14. März 2011, 17:15–20:00, P3
The Nature of Water at Material Interfaces — •Kai F. Hodeck1, Kathrin M. Lange1, Ulrich Schade1, Andrei P. Sommer2, Dan Zhu2, Alexander Kothe1, and Emad F. Aziz1, 3 — 1Helmholtz-Zentrum Berlin für Materialien und Energie — 2Universität Ulm — 3Freie Universität Berlin
We studied the hydrogen bonding of water at the interface to sample materials of different polarity using soft X-ray absorption (XA) and Fourier transform infrared (FT-IR) spectroscopy. We show that the electronic structure of isolated water molecules in liquid solvents is neither like in the gas phase nor like in the bulk liquid phase, but rather like in ice [1]. Increasing the concentration gives rise to a solvent-specific clustering of the water molecules and the formation of distinct structures of the hydrogen bonding network: While in the polar acetonitrile environment, a shared solvation leads to string-like water structures, the less polar chloroform solvent facilitates an immediate phase separation, and a clustering of the water molecules. At the interface to the non-polar benzene solvent, a preferential orientation of the water molecules is found, which we interpret in terms of a formation of cage-like structures [1]. Upon going to the layering structure of water at extended hydrophobic interfaces we provide evidence for a strong, direct interaction with visible light as it is unknown for the bulk liquid [2, 3]. [1] K. Lange et al.: The Nature of the Hydrogen Bond of Water in Solvents of Different Polarities, The Journal of Physical Chemistry B; in print, DOI: 10.1021/jp109790z [2] A. Sommer et al.: Tuning Nanoscopic Water Layers with Laser Light. Langmuir, 24, 635