Thomas John, Patwari Jayita, Langguth Inga Christina, Penschke Christopher, Zhou Ping, Morgenstern Karina, Bovensiepen Uwe
Faculty of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, Lotharstr. 1, Duisburg 47057, Germany.
Physical Chemistry I, Ruhr-University Bochum, Universitätsstr. 150, Bochum 44801, Germany.
J Phys Chem C Nanomater Interfaces. 2023 Nov 17;127(48):23467-23474. doi: 10.1021/acs.jpcc.3c06172. eCollection 2023 Dec 7.
Hydrogen bonding is essential in electron-transfer processes at water-electrode interfaces. We study the impact of the H-bonding of water as a solvent molecule on real-time electron-transfer dynamics across a Cs-Cu(111) ion-metal interface using femtosecond time-resolved two-photon photoelectron spectroscopy. We distinguish in the formed water-alkali aggregates two regimes below and above two water molecules per ion. Upon crossing the boundary of these regimes, the lifetime of the excess electron localized transiently at the Cs ion increases from 40 to 60 fs, which indicates a reduced alkali-metal interaction. Furthermore, the energy transferred to a dynamic structural rearrangement due to hydration is reduced from 0.3 to 0.2 eV concomitantly. These effects are a consequence of H-bonding in the water-water interaction and the beginning formation of a nanoscale water network. This finding is supported by real-space imaging of the solvatomers and vibrational frequency shifts of the OH stretching and bending modes calculated for these specific interfaces.
氢键在水-电极界面的电子转移过程中至关重要。我们使用飞秒时间分辨双光子光电子能谱研究了作为溶剂分子的水的氢键对跨Cs-Cu(111)离子-金属界面的实时电子转移动力学的影响。我们在形成的水-碱聚集体中区分了每个离子低于和高于两个水分子的两种状态。当越过这些状态的边界时，暂时定域在Cs离子上的多余电子的寿命从40飞秒增加到60飞秒，这表明碱金属相互作用减弱。此外，由于水合作用转移到动态结构重排的能量也相应地从0.3电子伏特降低到0.2电子伏特。这些效应是水-水相互作用中氢键以及纳米级水网络开始形成的结果。这一发现得到了溶剂化物的实空间成像以及针对这些特定界面计算的OH伸缩和弯曲模式的振动频率偏移的支持。
