1. Institute of Chemistry of New Materials and Center of Physics and Chemistry of New Materials, Universität Osnabrück, Barbarastrasse 7, D-49076 Osnabrück, Germany
2. Department of Physics, Universität Osnabrück, Barbarastraße 7, D-49069 Osnabrück, Germany
3. Institute of Physical Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstr. 28/30, D-48149 Münster, Germany
4. Faculty of Agricultural Science and Landscape Architecture, Laboratory of Plant Nutrition and Chemistry, Osnabrück University of Applied Sciences, Am Krümpel 31, D-49090 Osnabrück, Germany