All-XUV Pump-Probe Transient Absorption Spectroscopy of the Structural Molecular Dynamics of Di-iodomethane
All-XUV Pump-Probe Transient Absorption Spectroscopy of the Structural Molecular Dynamics of Di-iodomethane
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DOI：
10.1103/physrevx.11.031001
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发表时间：
2021-07-01
影响因子：
12.5
通讯作者：
Pfeifer, Thomas
中科院分区：
文献类型：
--
作者：
Rebholz, Marc;Ding, Thomas;Pfeifer, Thomas
在这项工作中，我们使用极紫外光(XUV)自由电子激光(FEL)共振激发气相二碘甲烷(CH2I2)靶的I：4D(5/2)(-sigma*)跃迁。这种特定位置的激发产生了位于碘位置的4d核心空穴，使分子处于明确的激发状态。随后，我们用以同一I：4D共振为中心的自由电子激光探针光谱测量了分子的吸收随时间的变化。利用从头计算早期研究中观察到的瞬时异构化途径的吸收光谱，我们的时间分辨测量使我们能够指定先前报道的直接和间接解离途径的时间尺度。因此，该方法是敏感的激发态分子几何以时间分辨的方式，遵循核心共振位特定触发。
In this work, we use an extreme-ultraviolet (XUV) free-electron laser (FEL) to resonantly excite the I:4d(5/2)(-sigma*) transition of a gas-phase di-iodomethane (CH2I2) target. This site-specific excitation generates a 4d core hole located at an iodine site, which leaves the molecule in a well-defined excited state. We subsequently measure the time-dependent absorption change of the molecule with the FEL probe spectrum centered on the same I: 4d resonance. Using ab initio calculations of absorption spectra of a transient isomerization pathway observed in earlier studies, our time-resolved measurements allow us to assign the timescales of the previously reported direct and indirect dissociation pathways. The presented method is thus sensitive to excited-state molecular geometries in a time-resolved manner, following a core-resonant site-specific trigger.