Developing femtosecond resolution methods for directly observing structural dynamics is critical to understanding complex photochemical reaction mechanisms in solution. We have used two recent developments, ultrafast mega-electron-volt electron sources and vacuum compatible sub-micron thick liquid sheet jets, to enable liquid-phase ultrafast electron diffraction (LUED). We have demonstrated the viability of LUED by investigating the photodissociation of tri-iodide initiated with a 400 nm laser pulse. This has enabled the average speed of the bond expansion to be measured during the first 750 fs of dissociation and the geminate recombination to be directly captured on the picosecond time scale.

中文翻译：

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通过液相超快兆电子伏电子衍射观察水相 I3 的光解离

开发直接观察结构动力学的飞秒分辨率方法对于理解溶液中复杂的光化学反应机制至关重要。我们使用了两项最新进展，即超快兆电子伏电子源和真空兼容的亚微米厚液体片射流，以实现液相超快电子衍射（LUED）。我们通过研究 400 nm 激光脉冲引发的三碘化物的光解，证明了 LUED 的可行性。这使得在解离的前 750 fs 期间可以测量键扩展的平均速度，并且可以在皮秒时间尺度上直接捕获双联重组。