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Surface Charges at the CaF 2 /Water Interface Allow Very Fast Intermolecular Vibrational‐Energy Transfer
Author(s) -
Lesnicki Dominika,
Zhang Zhen,
Bonn Mischa,
Sulpizi Marialore,
Backus Ellen H. G.
Publication year - 2020
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.202004686
Subject(s) - chemical physics , vibrational energy relaxation , solvation , intermolecular force , molecule , relaxation (psychology) , molecular dynamics , chemistry , molecular vibration , picosecond , dipole , materials science , computational chemistry , optics , psychology , social psychology , laser , physics , organic chemistry
Abstract 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 2 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 −1 , display very rapid spectral diffusion and vibrational relaxation; for weakly H‐bonded OD groups, above 2500 cm −1 , 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.