该研究团队利用来自X射线自由电子激光器的同步阿秒X射线脉冲对，通过全X射线阿秒瞬态吸收光谱(AX-ATAS)研究了液态水中价电离的电子响应。分析表明，AX-ATAS响应局限于亚飞秒时间尺度，消除了任何氢原子运动，并通过实验证明X射线发射光谱中的1b1分裂与动力学有关，而不是环境液态水中存在两个结构基序的证据。
据悉，阿秒-泵浦/阿秒-探针实验一直被认为是实时观察电子动力学的最直接的方法。虽然与理论相结合的近红外飞秒和极紫外阿秒脉冲叠加已经取得了很大的成功，但真正的阿秒泵浦/阿秒探针实验仍然有限。
附：英文原文
Title: Attosecond-pump attosecond-probe x-ray spectroscopy of liquid water
Author: Shuai Li, Lixin Lu, Swarnendu Bhattacharyya, Carolyn Pearce, Kai Li, Emily T. Nienhuis, Gilles Doumy, R. D. Schaller, S. Moeller, M.-F. Lin, G. Dakovski, D. J. Hoffman, D. Garratt, Kirk A. Larsen, J. D. Koralek, C. Y. Hampton, D. Cesar, Joseph Duris, Z. Zhang, Nicholas Sudar, James P. Cryan, A. Marinelli, Xiaosong Li, Ludger Inhester, Robin Santra, Linda Young
Issue&Volume: 2024-03-08
Abstract: Attosecond-pump/attosecond-probe experiments have long been sought as the most straightforward method for observing electron dynamics in real time. Although there has been much success with overlapped near-infrared femtosecond and extreme ultraviolet attosecond pulses combined with theory, true attosecond-pump/attosecond-probe experiments have been limited. We used a synchronized attosecond x-ray pulse pair from an x-ray free-electron laser to study the electronic response to valence ionization in liquid water through all x-ray attosecond transient absorption spectroscopy (AX-ATAS). Our analysis showed that the AX-ATAS response is confined to the subfemtosecond timescale, eliminating any hydrogen atom motion and demonstrating experimentally that the 1b1 splitting in the x-ray emission spectrum is related to dynamics and is not evidence of two structural motifs in ambient liquid water.
Source: https://www.science.org/doi/10.1126/science.adn6059