1. R&D Department, Philochem AG, CH-8112 Otelfingen, Switzerland
2. Department of Physics, University of Cagliari, Cagliari I-09042, Monserrato, Italy
3. Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, CH-8093 Zurich, Switzerland
4. Philogen S.p.A., I-53100 Siena, Italy