1. X-ray Microspectroscopy and Imaging Group, Department of Chemistry, Ghent University, Krijgslaan 281, B-9000 Ghent, Belgium
2. Institute for Geosciences, Goethe University Frankfurt, Altenhöferallee 1, 60438 Frankfurt am Main, Germany
3. Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany