1. Department of Physics, Institute of Quantum Electronics, ETH Zurich, 8093 Zurich, Switzerland
2. Laboratorium für Physikalische Chemie, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
3. Department of Physics, University of Zurich, 8057 Zürich, Switzerland
4. Laboratoire de Spectroscopie Ultrarapide (LSU), and Lausanne Centre for Ultrafast Science (LACUS), ISIC-FSB, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
5. Laboratory of Computational Chemistry and Biochemistry, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland