1. KU LeuvenDivision of Molecular Imaging and Photonics, Department of Chemistry Celestijnenlaan 200F B-3001 Leuven Belgium
2. Max Planck Institute for Polymer Research Ackermannweg 10 55128 Mainz Germany
3. Current address: Molecular Materials and Nanosystems, Institute for Complex Molecular SystemsEindhoven University of Technology P.O. Box 513 5600 MB Eindhoven The Netherlands
4. Department of Molecular Physics, Faculty of ChemistryLodz University of Technology Zeromskiego 116 90-924 Lodz Poland