1. Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado 80521, United States
2. Atmospheric Chemistry Division, National Center for Atmospheric Research, Boulder, Colorado 80301, United States
3. Department of Chemistry and Biochemistry, University of Montana, Missoula, Montana 59812, United States
4. Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
5. Department of Chemistry, University of California, Irvine, California 92697, United States