1. Chemical Sciences Laboratory National Oceanic and Atmospheric Administration Boulder CO USA
2. Department of Chemistry York University Toronto ON Canada
3. University of Maryland Baltimore County Baltimore MD USA
4. Now at: Division of Chemistry and Chemical Engineering California Institute of Technology Pasadena CA USA
5. Department of Chemistry University of Colorado Boulder CO USA
6. Cooperative Institute for Research in Environmental Sciences University of Colorado Boulder CO USA
7. Now at: National Center for Atmospheric Research Boulder CO USA
8. Department of Atmospheric Sciences University of Washington Seattle WA USA
9. Air Quality Research Division Environment and Climate Change Canada Toronto ON Canada
10. Earth, Ocean, and Atmospheric Science Florida State University Tallahassee FL USA
11. Space Science and Engineering Center University of Wisconsin Madison WI USA