1. Department of Chemistry and The PULSE Institute, Stanford University, Stanford, California 94305, United States
2. SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
3. Biophysics Program, Stanford University, Stanford, California 94305, United States
4. Department of Chemistry, Norwegian University of Science and Technology, NTNU, 7491 Trondheim, Norway
5. Scuola Normale Superiore, Piazza dei Cavaleri 7, 56126 Pisa, Italy