1. Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
2. Department of Chemistry, Stanford University, Stanford, California 94305, United States
3. Department of Chemistry, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
4. Scuola Normale Superiore, Piazza dei Cavalieri, 7, 56126 Pisa, PI, Italy
5. Institut für Physik und Astronomie, Universität Potsdam, 14476 Potsdam, Germany