Fukuzawa Hironobu, Takanashi Tsukasa, Kukk Edwin, Motomura Koji, Wada Shin-Ichi, Nagaya Kiyonobu, Ito Yuta, Nishiyama Toshiyuki, Nicolas Christophe, Kumagai Yoshiaki, Iablonskyi Denys, Mondal Subhendu, Tachibana Tetsuya, You Daehyun, Yamada Syuhei, Sakakibara Yuta, Asa Kazuki, Sato Yuhiro, Sakai Tsukasa, Matsunami Kenji, Umemoto Takayuki, Kariyazono Kango, Kajimoto Shinji, Sotome Hikaru, Johnsson Per, Schöffler Markus S, Kastirke Gregor, Kooser Kuno, Liu Xiao-Jing, Asavei Theodor, Neagu Liviu, Molodtsov Serguei, Ochiai Kohei, Kanno Manabu, Yamazaki Kaoru, Owada Shigeki, Ogawa Kanade, Katayama Tetsuo, Togashi Tadashi, Tono Kensuke, Yabashi Makina, Ghosh Aryya, Gokhberg Kirill, Cederbaum Lorenz S, Kuleff Alexander I, Fukumura Hiroshi, Kishimoto Naoki, Rudenko Artem, Miron Catalin, Kono Hirohiko, Ueda Kiyoshi
Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, 980-8577, Japan.
RIKEN SPring-8 Center, Sayo, Hyogo, 679-5148, Japan.
Nat Commun. 2019 May 16;10(1):2186. doi: 10.1038/s41467-019-10060-z.
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.
X射线自由电子激光（XFEL）可用性的不断提高，推动了单物体结构测定和实时结构动力学跟踪技术的发展。解析与XFEL脉冲相互作用引发的分子水平反应，是开发此类应用的基本步骤。在此，我们报告了使用飞秒近红外探测激光，对二碘甲烷分子中通过短寿命瞬态电子态发生的XFEL诱导电子衰变进行的实时观测。我们确定了XFEL诱导俄歇级联过程中所填充瞬态态的寿命，并发现多电荷碘离子源自短寿命（约20飞秒）的瞬态态，而单电荷碘离子则源自寿命长得多的态（约100飞秒）。我们确定了这些不同时间尺度背后的机制：与通过分子俄歇衰变弛豫的短寿命瞬态态不同，长寿命瞬态态在分子碎片化过程中通过两个碘原子之间的原子间库仑衰变而衰变。
