1. Inorganic Chemistry and Centre for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Universitaetsstr. 5-7, 45117 Essen, Germany
2. Organic Chemistry, University of Duisburg-Essen, Universitaetsstr. 5-7, 45117 Essen, Germany
3. Ernst Ruska Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich, 52428 Jülich, Germany
4. Max-Planck-Institut für Kohlenforschung, 45470 Mülheim an der Ruhr, Germany
5. Institute of Physics, University of São Paulo, São Paulo 05508-090, Brazil