Author Affiliations

T. J. A. Wolf,¹ R. H. Myhre,^1,2 J. P. Cryan,¹ S. Coriani,^3,4 R. J. Squibb,⁵ A. Battistoni,¹ N. Berrah,⁶ C. Bostedt,^7,8,9 P. Bucksbaum,^1,10 G. Coslovich,⁷ R. Feifel,⁵ K. J. Gaffney,¹ J. Grilj,¹¹ T. J. Martinez,^1,12 S. Miyabe,^1,12,13 S. P. Moeller,⁷ M. Mucke,¹⁴ A. Natan,¹ R. Obaid,⁶ T. Osipov,⁷ O. Plekan,¹⁵ S. Wang,¹ H. Koch,^1,2 and M. Gühr^1,16

¹Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA.

²Department of Chemistry, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.

³Dipartimento di Scienze Chimiche e Farmaceutiche, Università degli Studi di Trieste, Italy.

⁴Aarhus Institute of Advanced Studies, Aarhus University, DK-8000 Aarhus C, Denmark.

⁵Department of Physics, University of Gothenburg, Gothenburg, Sweden.

⁶Department of Physics, University of Connecticut, Storrs, Connecticut 06269, USA.

⁷Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94720, USA.

⁸Argonne National Laboratory, Lemont, Illinois 60439, USA.

⁹Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, USA.

¹⁰Department of Physics, Stanford University, Stanford, CA 94305, USA.

¹¹Laboratory of Ultrafast Spectroscopy, Ecole Polytechnique Federal de Lausanne, CH 1015 Switzerland.

¹²Department of Chemistry, Stanford University, Stanford, California 94305, USA.

¹³Laser Technology Laboratory, RIKEN, Wako, Saitama 351-0198, Japan

¹⁴Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden.

¹⁵Elettra-Sincrotrone Trieste, I-34149 Basovizza, Trieste, Italy.

¹⁶Institut für Physik und Astronomie, Universität Potsdam, 14476 Potsdam, Germany.