1. Paul Scherrer Institute, Laboratory of Environmental Chemistry, 5232 Villigen PSI, Switzerland
2. Department of Chemistry and Biochemistry, University of Bern, 2012 Bern, Switzerland
3. CNRS, UMR5256, IRCELYON, Univ. Lyon, Université Claude Bernard Lyon 1, CNRS, IRCELYON, F-69626, Villeurbanne, France