[1] Imperial Coll London, Blackett Lab, Quantum Opt & Laser Sci Grp, London SW7 2BW, England
[2] UCL, Dept Phys & Astron, Atom Mol Opt & Positron Phys Grp, Gower St, London WC1E 6BT, England
[3] SLAC Natl Accelerator Lab, Stanford PULSE Inst, Menlo Pk, CA 94025 USA
[4] SLAC Natl Accelerator Lab, Linac Coherent Light Source, Menlo Pk, CA 94025 USA
[5] SLAC Natl Accelerator Lab, Accelerator Directorate, Menlo Pk, CA 94025 USA
[6] Argonne Natl Lab, Chem Sci & Engn Div, Lemont, IL 60439 USA
[7] Paul Scherrer Inst, CH-5232 Villigen, Switzerland
[8] Uppsala Univ, Dept Phys & Astron, Box 516, S-75120 Uppsala, Sweden
[9] Lund Univ, MAX IV Lab, Box 118, SE-22100 Lund, Sweden
[10] Imperial Coll London, Dept Chem, Mol Sci Res Hub, London W12 0BZ, England
[11] Univ Connecticut, Dept Phys, Storrs, CT 06268 USA
[12] Ecole Polytech Fed Lausanne EPFL, LUXS Lab Ultrafast Xray Sci, Inst Chem Sci & Engn, CH-1015 Lausanne, Switzerland
[13] Orme Merisiers, Synchrotron SOLEIL, BP 48, F-91192 Gif Sur Yvette, France
[14] Ecole Polytech Fed Lausanne, Lab Mol Nanodynam, CH-1015 Lausanne, Switzerland
[15] Univ Gothenburg, Dept Phys, Origovagen 6B, S-41258 Gothenburg, Sweden
[16] Charles Univ Prague, Fac Math & Phys, Inst Theoret Phys, V Holesovickach 2, Prague 18000, Czech Republic
[17] Univ Nantes, CNRS, CEISAM UMR 6230, F-44000 Nantes, France
[18] Tohoku Univ, Inst Multidisciplinary Res Adv Mat, Sendai, Miyagi 9808577, Japan
[19] Tohoku Univ, Dept Chem, Aoba Ku, 6-3 Aramaki Aza Aoba, Sendai, Miyagi 9808578, Japan