1 Department of Chemistry, The University of Chicago, Chicago, IL 60637; Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL 60637; James Franck Institute, The University of Chicago, Chicago, IL 60637;
2 Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL 60637; James Franck Institute, The University of Chicago, Chicago, IL 60637; Graduate Program in the Biophysical Sciences, The University of Chicago, Chicago, IL 60637.
3 Department of Chemistry, The University of Chicago, Chicago, IL 60637; Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL 60637; James Franck Institute, The University of Chicago, Chicago, IL 60637; gsengel@uchicago.edu.