Li Xiang, Boll Rebecca, Vindel-Zandbergen Patricia, González-Vázquez Jesús, Rivas Daniel E, Bhattacharyya Surjendu, Borne Kurtis, Chen Keyu, De Fanis Alberto, Erk Benjamin, Forbes Ruaridh, Green Alice E, Ilchen Markus, Kaderiya Balram, Kukk Edwin, Lam Huynh Van Sa, Mazza Tommaso, Mullins Terence, Senfftleben Björn, Trinter Florian, Usenko Sergey, Venkatachalam Anbu Selvam, Wang Enliang, Cryan James P, Meyer Michael, Jahnke Till, Ho Phay J, Rolles Daniel, Rudenko Artem
Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA, USA.
European XFEL, Holzkoppel 4, Schenefeld, Germany.
Nat Commun. 2025 Jul 30;16(1):7006. doi: 10.1038/s41467-025-62274-z.
Tracking the motion of individual atoms during chemical reactions represents a severe experimental challenge, especially if several competing reaction pathways exist or if the reaction is governed by the correlated motion of more than two molecular constituents. Here we demonstrate how ultrashort X-ray pulses combined with coincident ion imaging can be used to trace molecular iodine elimination from laser-irradiated diiodomethane (CHI), a reaction channel of fundamental importance but small relative yield that involves the breaking of two molecular bonds and the formation of a new one. We map bending vibrations of the bound molecule, disentangle different dissociation pathways, image the correlated motion of the iodine atoms and the methylene group leading to molecular iodine ejection, and trace the vibrational motion of the formed product. Our results provide a quantitative mechanistic picture behind previously suggested reaction mechanisms and prove that a variety of geometries are involved in the molecular bond formation.
追踪化学反应过程中单个原子的运动是一项极具挑战性的实验任务，特别是当存在多个相互竞争的反应路径，或者反应由两个以上分子成分的关联运动所主导时。在此，我们展示了如何将超短X射线脉冲与符合离子成像相结合，用于追踪激光辐照二碘甲烷（CH₂I₂）中分子碘的消除过程。这是一个具有根本重要性但相对产率较低 的反应通道，涉及到两个分子键的断裂和一个新键的形成。我们绘制了束缚分子的弯曲振动，区分了不同的解离路径，对导致分子碘喷射的碘原子和亚甲基的关联运动进行成像，并追踪了形成产物的振动运动。我们的结果为先前提出的反应机制背后提供了定量的机理图景，并证明分子键形成涉及多种几何构型。
