1. SFI-Strategic Research Cluster in Solar Energy Conversion, Centre for Synthesis and Chemical Biology (CSCB), School of Chemical and Bioprocess Engineering, and School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland, Institut für Physikalische Chemie, Universität zu Köln, Luxemburger Strasse 116, 50939 Köln, Germany, and Physical Chemistry 1, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden