1. School of Life Sciences, Wood Research Munich (HFM), Technical University of Munich, Winzererstrasse 45, D-80797 Munich, Germany
2. Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria
3. Department of Chemistry, Technical University of Munich, Lichtenbergstrasse 4, D-85747 Garching, Germany
4. Department of Civil Geo and Environmental Engineering, Technical University of Munich, Arcisstrasse 21, D-80333 Munich, Germany