Dept. of Atmospheric Sciences, Texas A&M University, College Station, Texas 77843, USA

Dept. of Atmospheric Sciences, Texas A&M University, College Station, Texas 77843, USA

Dept. of Atmospheric Sciences, Texas A&M University, College Station, Texas 77843, USA

now at: Dept. of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, USA

Dept. of Chemistry and Biochemistry, University of Colorado at Boulder, Boulder CO, USA

Molina Center for Energy and the Environment, La Jolla, California and Massachusetts Institute of Technology, Cambridge, Massachusetts, USA

Molina Center for Energy and the Environment, La Jolla, California and Massachusetts Institute of Technology, Cambridge, Massachusetts, USA

Cooperative Institute for Research in the Environmental Sciences (CIRES), University of Colorado, Boulder, Colorado, USA

Dept. of Chemistry and Biochemistry, University of Colorado at Boulder, Boulder CO, USA

Cooperative Institute for Research in the Environmental Sciences (CIRES), University of Colorado, Boulder, Colorado, USA

Dept. of Chemistry and Biochemistry, University of Colorado at Boulder, Boulder CO, USA

Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, Switzerland

Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, Switzerland

Dept. of Chemistry, Indiana University, Bloomington, Indiana, USA

Dept. of Chemistry, Indiana University, Bloomington, Indiana, USA

Atmospheric Chemistry Division, National Center for Atmospheric Research, Boulder, Colorado, USA