1. Faculty of Physics and Earth Sciences, Felix Bloch Institute for Solid State Physics, Leipzig University, Linnéstraße 5, 04103 Leipzig, Germany
2. Institute of Inorganic and Applied Chemistry, Hamburg University, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany
3. Institute of Physical Chemistry, Hamburg University, Grindelallee 177, 20146 Hamburg, Germany