1. Department of Physics, Ludwig-Maximilians-Universität München, D-85748 Garching, Germany
2. Max Planck Institute of Quantum Optics, D-85748 Garching, Germany
3. Centre for Quantum Dynamics and Australian Attosecond Science Facility, Griffith University, Nathan, QLD 4111, Australia
4. Department of Chemistry and Biochemistry, Ludwig-Maximilians-Universität München, D-81377 Munich, Germany
5. Énergie, Matériaux et Télécommunications, Institut National de la Recherche Scientifique, Varennes, Quebec J3X 1P7, Canada
6. Université de Bordeaux-CNRS-CEA, CELIA, UMR 5107, F-33405 Talence, France
7. Department of Physics, American University of Sharjah, PO Box 26666, Sharjah, United Arab Emirates
8. Materials Science and Engineering Research Institute, American University of Sharjah, PO Box 26666, Sharjah, United Arab Emirates
9. Max Planck Institute of Nuclear Physics, D-69117 Heidelberg, Germany
10. National Research Council of Canada, 100 Sussex Dr, Ottawa, Ontario K1A0R6, Canada