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O: Fachverband Oberflächenphysik

O 31: Molecular Films: Properties and Preparation

O 31.2: Vortrag

Dienstag, 1. April 2014, 10:45–11:00, WIL A317

X-ray spectroscopic analysis of the electronic structure of aqueous salt solutions — •Yekkoni Jeyachandran¹, Frank Meyer², Andreas Benkert^2,3, Marcus Bär^4,5, Regan Wilks⁴, Monika Blum⁵, Wanli Yang⁶, Friedrich Reinert², Clemens Heske^3,5, Lothar Weinhardt^3,5, and Michael Zharnikov¹ — ¹Angew. Phys. Chemie, Universität Heidelberg. — ²Exp. Phys. VII, Universität Würzburg. — ³Inst. Photon Sci. Synchr. Rad., Karlsruhe Institute of Technology. — ⁴Sol. Energy Res., Helmholtz-Zentrum Berlin. — ⁵Dept. Chem., University of Nevada Las Vegas. — ⁶Advanced Light Source, Lawrence Berkeley National Laboratory.

Modification of the molecular structure of water in the presence of ionic salts is of primary importance for a variety of chemical and biochemical processes. Advanced soft X-ray spectroscopic techniques, which provide information on the local electronic structure of molecules, can be used to probe such a modification. In this work, using a specially designed experimental setup, we studied the electronic structure of water molecules in aqueous alkali halide and calcium chloride solutions by non-resonant and resonant X-ray emission spectroscopy (XES). Significant changes in the characteristic emission spectra of water were observed at the variation of the salt concentration, with the extent and character depending on the size and valence state of the involved anions and cations. The observed spectral changes are discussed in terms of the disturbances of the hydrogen bond network of water molecules induced by the salts. These changes are accompanied by the changes in the electronic structure of water, which can be traced by XES.