Smith Adam D, Balčiu Nas Tadas, Chang Yi-Ping, Schmidt Cédric, Zinchenko Kristina, Nunes Fernanda B, Rossi Emanuele, Svoboda Vít, Yin Zhong, Wolf Jean-Pierre, Wörner Hans Jakob
Laboratory of Physical Chemistry, ETH Zürich, 8093 Zürich, Switzerland.
GAP-Biophotonics, Université de Genéve, 1205 Geneva, Switzerland.
J Phys Chem Lett. 2020 Mar 19;11(6):1981-1988. doi: 10.1021/acs.jpclett.9b03559. Epub 2020 Feb 26.
Femtosecond X-ray absorption spectroscopy (XAS) is a powerful method to investigate the dynamical behavior of a system after photoabsorption in real time. So far, the application of this technique has remained limited to large-scale facilities, such as femtosliced synchrotrons and free-electron lasers (FEL). In this work, we demonstrate femtosecond time-resolved soft-X-ray absorption spectroscopy of liquid samples by combining a sub-micrometer-thin flat liquid jet with a high-harmonic tabletop source covering the entire water-window range (284-538 eV). Our work represents the first extension of tabletop XAS to the oxygen edge of a chemical sample in the liquid phase. In the time domain, our measurements resolve the gradual appearance of absorption features below the carbon K-edge of ethanol and methanol during strong-field ionization and trace the valence-shell ionization dynamics of the liquid alcohols with a temporal resolution of ∼30 fs. This technique opens unique opportunities to study molecular dynamics of chemical systems in the liquid phase with elemental, orbital, and site sensitivity.
飞秒X射线吸收光谱（XAS）是一种用于实时研究光吸收后系统动力学行为的强大方法。到目前为止，该技术的应用仍局限于大型设施，如飞秒切片同步加速器和自由电子激光（FEL）。在这项工作中，我们通过将亚微米级薄的扁平液体射流与覆盖整个水窗范围（284 - 538 eV）的高谐波桌面光源相结合，展示了液体样品的飞秒时间分辨软X射线吸收光谱。我们的工作代表了桌面XAS首次扩展到液相化学样品的氧边缘。在时域中，我们的测量解析了强场电离过程中乙醇和甲醇碳K边缘以下吸收特征的逐渐出现，并以约30 fs的时间分辨率追踪了液体醇类的价壳层电离动力学。这项技术为研究具有元素、轨道和位点敏感性的液相化学系统的分子动力学提供了独特的机会。
