1. Institute of Physics of Rennes, CNRS-University of Rennes 1, UMR 6251, F-35042 Rennes, France
2. Institute for Materials and X-ray Physics, Hamburg University of Technology, 21073 Hamburg, Germany
3. Centre for X-ray and Nano Science CXNS, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
4. Centre for Hybrid Nanostructures CHyN, Hamburg University, 22607 Hamburg, Germany
5. Institute of Inorganic and Applied Chemistry, University of Hamburg, 20146 Hamburg, Germany