Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max Born Strasse 2A, 12489, Berlin, Germany.
Institute for Nanostructure and Solid State Physics, Center for Free-Electron Laser Science, Luruper Chaussee 149, 22761, Hamburg, Germany.
Angew Chem Int Ed Engl. 2022 Nov 14;61(46):e202211066. doi: 10.1002/anie.202211066. Epub 2022 Oct 25.
Seemingly simple yet surprisingly difficult to probe, excess protons in water constitute complex quantum objects with strong interactions with the extended and dynamically changing hydrogen-bonding network of the liquid. Proton hydration plays pivotal roles in energy transport in hydrogen fuel cells and signal transduction in transmembrane proteins. While geometries and stoichiometry have been widely addressed in both experiment and theory, the electronic structure of these specific hydrated proton complexes has remained elusive. Here we show, layer by layer, how utilizing novel flatjet technology for accurate x-ray spectroscopic measurements and combining infrared spectral analysis and calculations, we find orbital-specific markers that distinguish two main electronic-structure effects: Local orbital interactions determine covalent bonding between the proton and neigbouring water molecules, while orbital-energy shifts measure the strength of the extended electric field of the proton.
看似简单却又难以深入探究，水中多余的质子构成了复杂的量子物体，它们与液体中延展且动态变化的氢键网络有着强烈的相互作用。质子水合作用在氢燃料电池中的能量传输和跨膜蛋白中的信号转导中起着关键作用。虽然在实验和理论中已经广泛研究了几何形状和化学计量比，但这些特定的质子水合复合物的电子结构仍然难以捉摸。在这里，我们逐层展示了如何利用新型平面喷射技术进行精确的 X 射线光谱测量，并结合红外光谱分析和计算，发现了区分两种主要电子结构效应的轨道特异性标记：局部轨道相互作用决定了质子与相邻水分子之间的共价键，而轨道能量位移则衡量了质子扩展电场的强度。
