1. Department of Chemistry and the James Franck Institute, University of Chicago, Chicago, Illinois 60637, United States
2. Graduate Program in the Biophysical Sciences, the James Franck Institute, and The Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637, United States
3. The Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637, United States
4. Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439, United States
5. Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States