Novel Ultrafast Molecular Imaging Based on the Combination of X-ray and Electron Diffraction
Novel Ultrafast Molecular Imaging Based on the Combination of X-ray and Electron Diffraction
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基于 X 射线和电子衍射相结合的新型超快分子成像
DOI：
10.1021/acs.jpca.2c08024
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Mukamel, Shaul
中科院分区：
文献类型：
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作者：
Yong, Haiwang;Keefer, Daniel;Mukamel, Shaul
X射线自由电子激光器和兆电子伏射频电子枪的最新发展使得超快X射线和电子衍射测量成为可能，从而以原子空间和飞秒时间分辨率捕获化学动力学。我们为这两种技术提出了标准零差检测和外差检测信号的统一公式。注意到 X 射线从分子电子散射，而电子从分子电子和原子核散射，我们展示了如何组合这两种衍射信号来揭示单独使用每种技术无法获得的新化学信息。通过减去零差检测到的 X 射线和电子衍射信号，可以通过自外差性质识别电子衍射中的混合电子-核干扰，用于阿秒电子动力学的直接成像，其中分子核的散射充当分子电子散射的本地振荡器。通过减去外差检测的 X 射线和电子衍射，可以选出纯核电荷密度。
Recent development of X-ray free-electron lasers and megaelectronvolt radio-frequency electron guns have made ultrafast X-ray and electron diffraction measurements possible, thereby capturing chemical dynamics with atomic-spatial and femtosecond-temporal resolutions. We present a unified formulation of standard homodyne-detected and heterodyne-detected signals for both techniques. Noting that X-rays scatter from molecular electrons while electrons scatter from both molecular electrons and nuclei, we show how the two diffraction signals can be combined to reveal novel chemical information that is unavailable by solely using each technique alone. By subtracting the homodyne-detected X-ray and electron diffraction signals, a mixed electronic–nuclear interference in electron diffraction can be identified with a self-heterodyne nature for the direct imaging of attosecond electron dynamics where the scattering off molecular nuclei serves as a local oscillator for the scattering off molecular electrons. By subtracting heterodyne-detected X-ray and electron diffraction, the purely nuclear charge density can be singled out.