The ultrafast structural dynamics of water following inner-shell ionization is a crucial issue in high-energy radiation chemistry. We have exposed isolated water molecules to a short x-ray pulse from a free-electron laser and detected momenta of all produced ions in coincidence. By combining experimental results and theoretical modeling, we can image dissociation dynamics of individual molecules in unprecedented detail. We reveal significant molecular structural dynamics in ${\mathrm{H}}_2{\mathrm{O}}^{2+}$, such as asymmetric deformation and bond-angle opening, leading to two-body or three-body fragmentation on a timescale of a few femtoseconds. We thus reconstruct several snapshots of structural dynamics at different time intervals, which highlight dynamical patterns that are relevant as initiating steps of subsequent radiation-damage processes.

中文翻译：

---

在 X 射线自由电子激光器成像的水分子的内壳电离诱导飞秒结构动力学

内壳电离后水的超快结构动力学是高能辐射化学中的一个关键问题。我们将孤立的水分子暴露在来自自由电子激光器的短 X 射线脉冲下，并同时检测到所有产生的离子的动量。通过结合实验结果和理论模型，我们可以以前所未有的细节对单个分子的解离动力学进行成像。我们揭示了重要的分子结构动力学${\mathrm{H}}_2{\mathrm{哦}}^{2+}$，例如不对称变形和键角打开，导致在几飞秒的时间尺度上发生两体或三体碎裂。因此，我们在不同的时间间隔重建了结构动力学的几个快照，这些快照突出了与后续辐射损伤过程的启动步骤相关的动力学模式。