1. Research Institute for Electron Microscopy, Graz University of Technology, Steyrergasse 17, A-8010 Graz, Austria, Institute of Physical Chemistry, University of Leoben, Franz-Josef-Strasse 18, A-8700 Leoben, Austria, Institute of Physical and Theoretical Chemistry, Graz University of Technology, Rechbauerstrasse 12, A-8010 Graz, Austria, and Institute of Chemistry, Karl-Franzens-University of Graz, Schubertstrasse 1, A-8010 Graz, Austria