1. Department
of Chemistry, Memorial University, St. John’s, Newfoundland A1B 3X5, Canada
2. Cooperative
Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, Colorado 80309, United States
3. Chemical
Sciences Division, Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, Colorado 80305, United States
4. Atmospheric Research & Analysis Inc., Cary, North Carolina 27513, United States