1. Physical Chemistry Institute, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland, Institute of Experimental Physics, Free University of Berlin, Arnimallee 14, DE-14195 Berlin, Germany, and Interdisciplinary Research Group “Time-Resolved Spectroscopy”, Faculty of Chemistry and Mineralogy, University of Leipzig, Permoserstrasse 15, DE-04318 Leipzig, Germany