1. School of Earth and Atmospheric Sciences; Georgia Institute of Technology; Atlanta Georgia USA
2. NASA Langley Research Center; Hampton Virginia USA
3. National Exposure Research Laboratory; US Environmental Protection Agency; Research Triangle Park North Carolina USA
4. Atmospheric Chemistry Division; National Center for Atmospheric Research; Boulder Colorado USA
5. Institut für Ionenphysik und Angewandte Physik; Universität Innsbruck; Innsbruck Austria
6. Department of Chemistry; University of Oslo; Oslo Norway
7. Oak Ridge Associated Universities; Oak Ridge Tennessee United States
8. Now at Department of Chemistry; University of Oslo; Oslo Norway
9. University of Colorado Boulder; Boulder; Colorado USA