1. Section for Environmental Sciences, Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, NO-0315 Oslo, Norway
2. Aix Marseille Univ, CNRS, LCE, UMR 7376, 13331 Marseille, France
3. Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, P.O. Box 5003, N-1432 Ås, Norway
4. Wolfson Atmospheric Chemistry Laboratories, Department of Chemistry, University of York, York YO10 5DD, U. K.
5. School of Chemistry, University of Leeds, Leeds LS2 9JT, U. K.