Lesnicki Dominika, Zhang Zhen, Bonn Mischa, Sulpizi Marialore, Backus Ellen H G
Institute of Physics, Johannes, Gutenberg University Mainz, Staudingerweg 7, 55099, Mainz, Germany.
Department for Molecular Spectroscopy, Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany.
Angew Chem Int Ed Engl. 2020 Jul 27;59(31):13116-13121. doi: 10.1002/anie.202004686. Epub 2020 May 29.
We investigate the dynamics of water in contact with solid calcium fluoride, where at low pH, localized charges can develop upon fluorite dissolution. We use 2D surface-specific vibrational spectroscopy to quantify the heterogeneity of the interfacial water (D O) molecules and provide information about the sub-picosecond vibrational-energy-relaxation dynamics at the buried solid/liquid interface. We find that strongly H-bonded OD groups, with a vibrational frequency below 2500 cm , display very rapid spectral diffusion and vibrational relaxation; for weakly H-bonded OD groups, above 2500 cm , the dynamics slows down substantially. Atomistic simulations based on electronic-structure theory reveal the molecular origin of energy transport through the local H-bond network. We conclude that strongly oriented H-bonded water molecules in the adsorbed layer, whose orientation is pinned by the localized charge defects, can exchange vibrational energy very rapidly due to the strong collective dipole, compensating for a partially missing solvation shell.
我们研究了与固体氟化钙接触的水的动力学，在低pH值下，萤石溶解时会产生局部电荷。我们使用二维表面特异性振动光谱来量化界面水（D O）分子的不均匀性，并提供有关埋入的固/液界面处亚皮秒级振动能量弛豫动力学的信息。我们发现，振动频率低于2500 cm的强氢键OD基团表现出非常快速的光谱扩散和振动弛豫；对于高于2500 cm的弱氢键OD基团，动力学显著减慢。基于电子结构理论的原子模拟揭示了通过局部氢键网络进行能量传输的分子起源。我们得出结论，吸附层中强取向的氢键水分子，其取向由局部电荷缺陷固定，由于强集体偶极子，可以非常快速地交换振动能量，弥补部分缺失的溶剂化壳层。
