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Direct observation of coherent femtosecond solvent reorganization coupled to intramolecular electron transfer
Nature Chemistry ( IF 19.2 ) Pub Date : 2021-02-15 , DOI: 10.1038/s41557-020-00629-3
Elisa Biasin 1 , Zachary W Fox 2 , Amity Andersen 3 , Kathryn Ledbetter 1 , Kasper S Kjær 1, 4 , Roberto Alonso-Mori 5 , Julia M Carlstad 2, 6 , Matthieu Chollet 5 , James D Gaynor 2, 6 , James M Glownia 5 , Kiryong Hong 7, 8 , Thomas Kroll 5 , Jae Hyuk Lee 7, 9 , Chelsea Liekhus-Schmaltz 2 , Marco Reinhard 1 , Dimosthenis Sokaras 5 , Yu Zhang 10, 11 , Gilles Doumy 12 , Anne Marie March 12 , Stephen H Southworth 12 , Shaul Mukamel 10 , Kelly J Gaffney 1 , Robert W Schoenlein 1, 5 , Niranjan Govind 13 , Amy A Cordones 1 , Munira Khalil 2
Affiliation  

It is well known that the solvent plays a critical role in ultrafast electron-transfer reactions. However, solvent reorganization occurs on multiple length scales, and selectively measuring short-range solute–solvent interactions at the atomic level with femtosecond time resolution remains a challenge. Here we report femtosecond X-ray scattering and emission measurements following photoinduced charge-transfer excitation in a mixed-valence bimetallic (FeiiRuiii) complex in water, and their interpretation using non-equilibrium molecular dynamics simulations. Combined experimental and computational analysis reveals that the charge-transfer excited state has a lifetime of 62 fs and that coherent translational motions of the first solvation shell are coupled to the back electron transfer. Our molecular dynamics simulations identify that the observed coherent translational motions arise from hydrogen bonding changes between the solute and nearby water molecules upon photoexcitation, and have an amplitude of tenths of ångströms, 120–200 cm−1 frequency and ~100 fs relaxation time. This study provides an atomistic view of coherent solvent reorganization mediating ultrafast intramolecular electron transfer.



中文翻译:

耦合到分子内电子转移的相干飞秒溶剂重组的直接观察

众所周知,溶剂在超快电子转移反应中起着至关重要的作用。然而,溶剂重组发生在多个长度尺度上,并且在原子水平上以飞秒时间分辨率选择性地测量短程溶质-溶剂相互作用仍然是一个挑战。在这里,我们报告了混合价双金属 (Fe ii Ru iii ) 中光诱导电荷转移激发后的飞秒 X 射线散射和发射测量) 水中的复合物,以及使用非平衡分子动力学模拟对其进行解释。结合实验和计算分析表明,电荷转移激发态的寿命为 62 fs,并且第一个溶剂化层的相干平移运动与背电子转移耦合。我们的分子动力学模拟确定观察到的相干平移运动是由光激发时溶质和附近水分子之间的氢键变化引起的,并且具有十分之一埃的振幅、120-200 cm -1频率和~100 fs 弛豫时间。这项研究提供了介导超快分子内电子转移的相干溶剂重组的原子论观点。

更新日期:2021-02-15
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