1. Lehrstuhl für Physikalische Chemie I, Universitätsstrasse 150, 44801 Bochum, Germany, Institute of Physics, Jagiellonian University, ul. Reymonta 4, PL 30-059 Krakow, Poland, and School of Chemistry, University of St. Andrews, North Haugh, St. Andrews, Fife KY16 9ST, United Kingdom