1. Center for Atmospheric Particle Studies, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
2. Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
3. Chemical Sciences Division, National Oceanic and Atmospheric Administration, Earth Systems Research Laboratory, Boulder, Colorado 80305, United States
4. Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado 80309, United States
5. R. J. Lee Group Inc., Monroeville, Pennsylvania 15146, United States