Authors: N D Loh; C Y Hampton; A V Martin; D Starodub; R G Sierra; A Barty; A Aquila; J Schulz; L Lomb; J Steinbrener; R L Shoeman; S Kassemeyer; C Bostedt; J Bozek; S W Epp; B Erk; R Hartmann; D Rolles; A Rudenko; B Rudek; L Foucar; N Kimmel; G Weidenspointner; G Hauser; P Holl; E Pedersoli; M Liang; M S Hunter; M M Hunter; L Gumprecht; N Coppola; C Wunderer; H Graafsma; F R N C Maia; T Ekeberg; M Hantke; H Fleckenstein; H Hirsemann; K Nass; T A White; H J Tobias; G R Farquar; W H Benner; S P Hau-Riege; C Reich; A Hartmann; H Soltau; S Marchesini; S Bajt; M Barthelmess; P Bucksbaum; K O Hodgson; L Strüder; J Ullrich; M Frank; I Schlichting; H N Chapman; M J Bogan Journal: Nature Date: 2012-06-27 Impact factor: 49.962