Schwan Raffael, Qu Chen, Mani Devendra, Pal Nitish, Schwaab Gerhard, Bowman Joel M, Tschumper Gregory S, Havenith Martina
Physical Chemistry II, Department of Chemistry and Biochemistry, Ruhr-Universität Bochum, Bochum, Germany.
Department of Chemistry Biochemistry, University of Maryland, College Park, MD, 20742, USA.
Angew Chem Int Ed Engl. 2020 Jul 6;59(28):11399-11407. doi: 10.1002/anie.202003851. Epub 2020 May 28.
Intermolecular interactions in bulk water are dominated by pairwise and non-pairwise cooperative interactions. While accurate descriptions of the pairwise interactions are available and can be tested by precise low-frequency spectra of the water dimer up to 550 cm , the same does not hold for the three-body interactions. Here, we report the first comprehensive spectrum of the water trimer in the frequency region from 70 to 620 cm using helium-nanodroplet isolation and free-electron lasers. By comparison to accompanying high-level quantum calculations, the experimentally observed intermolecular bands can be assigned. The transition frequencies of the degenerate translation, the degenerate in-plane and the non-degenerate out-of-plane libration, as well as additional bands of the out-of-plane librational mode are reported for the first time. These provide a benchmark for state-of-the-art water potentials and dipole-moment surfaces, especially with respect to three-body interactions.
bulk water中的分子间相互作用由成对和非成对协同相互作用主导。虽然成对相互作用有准确的描述，并且可以通过高达550 cm的水二聚体精确低频光谱进行测试，但三体相互作用并非如此。在这里，我们使用氦纳米液滴隔离和自由电子激光器，报告了水三聚体在70至620 cm频率范围内的首个综合光谱。通过与伴随的高水平量子计算进行比较，可以确定实验观察到的分子间谱带。首次报告了简并平移、简并面内和面外非简并振动的跃迁频率，以及面外振动模式的其他谱带。这些为最先进的水势和偶极矩表面提供了基准，特别是在三体相互作用方面。
