1. Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
2. Department of Medical Physics, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
3. Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
4. Department of Radiology, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
5. Life Sciences Division, TRIUMF, Vancouver, British Columbia V6T 2A3, Canada
6. Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada