1. Department of Chemistry, Missouri University of Science and Technology, Rolla, Missouri 65409, United States
2. Center for Research in Energy and Environment, Missouri University of Science and Technology, Rolla, Missouri 65409, United States
3. Center for Single Nanoparticle, Single Cell, and Single Molecule Monitoring, Missouri University of Science and Technology, Rolla, Missouri 65409, United States
4. Center for Environmental Solutions and Emergency Response, Office of Research and Development, U.S. Environmental Protection Agency, Cincinnati Ohio 45220, United States
5. PerkinElmer, Inc., Woodbridge, Ontario L4L 8H1, Canada