Open Access

Hironobu Fukuzawa, Tsukasa Takanashi, Edwin Kukk, Koji Motomura, Shin-ichi Wada, Kiyonobu Nagaya, Yuta Ito, Toshiyuki Nishiyama, Christophe Nicolas, Yoshiaki Kumagai, Denys Iablonskyi, Subhendu Mondal, Tetsuya Tachibana, Daehyun You, Syuhei Yamada, Yuta Sakakibara, Kazuki Asa, Yuhiro Sato, Tsukasa Sakai, Kenji Matsunami, Takayuki Umemoto, Kango Kariyazono, Shinji Kajimoto, Hikaru Sotome, Per Johnsson, Markus S. Schöffler, Gregor Kastirke, Kuno Kooser, Xiao-Jing Liu, Theodor Asavei, Liviu Neagu, Serguei Molodtsov, Kohei Ochiai, Manabu Kanno, Kaoru Yamazaki, Shigeki Owada, Kanade Ogawa, Tetsuo Katayama, Tadashi Togashi, Kensuke Tono, Makina Yabashi, Aryya Ghosh, Kirill Gokhberg, Lorenz S. Cederbaum, Alexander I. Kuleff, Hiroshi Fukumura, Naoki Kishimoto, Artem Rudenko, Catalin Miron, Hirohiko Kono, Kiyoshi Ueda

• The increasing availability of X-ray free-electron lasers (XFELs) has catalyzed the development of single-object structural determination and of structural dynamics tracking in real-time. Disentangling the molecular-level reactions triggered by the interaction with an XFEL pulse is a fundamental step towards developing such applications. Here we report real-time observations of XFEL-induced electronic decay via short-lived transient electronic states in the diiodomethane molecule, using a femtosecond near-infrared probe laser. We determine the lifetimes of the transient states populated during the XFEL-induced Auger cascades and find that multiply charged iodine ions are issued from short-lived (∼20 fs) transient states, whereas the singly charged ones originate from significantly longer-lived states (∼100 fs). We identify the mechanisms behind these different time scales: contrary to the short-lived transient states which relax by molecular Auger decay, the long-lived ones decay by an interatomic Coulombic decay between two iodine atoms, during the molecular fragmentation.