核量子效应对液态水结构不均匀性的影响。
Impact of nuclear quantum effects on the structural inhomogeneity of liquid water.
作者信息
Berger Arian, Ciardi Gustavo, Sidler David, Hamm Peter, Shalit Andrey
机构信息
Department of Chemistry, University of Zurich, CH-8057 Zurich, Switzerland.
Department of Chemistry, University of Zurich, CH-8057 Zurich, Switzerland
出版信息
Proc Natl Acad Sci U S A. 2019 Feb 12;116(7):2458-2463. doi: 10.1073/pnas.1818182116. Epub 2019 Jan 28.
The 2D Raman-terahertz (THz) response of liquid water is studied in dependence of temperature and isotope substitution ([Formula: see text]O, [Formula: see text]O, and [Formula: see text]O). In either case, a very short-lived (i.e., between 75 and 95 fs) echo is observed that reports on the inhomogeneity of the low-frequency intermolecular modes and hence, on the heterogeneity of the hydrogen bond networks of water. The echo lifetime slows down by about 20% when cooling the liquid from room temperature to the freezing point. Furthermore, the echo lifetime of [Formula: see text]O is [Formula: see text] slower than that of [Formula: see text]O, and both can be mapped on each other by introducing an effective temperature shift of [Formula: see text] K. In contrast, the temperature-dependent echo lifetimes of [Formula: see text]O and [Formula: see text]O are the same within error. [Formula: see text]O and [Formula: see text]O have identical masses, yet [Formula: see text]O is much closer to [Formula: see text]O in terms of nuclear quantum effects. It is, therefore, concluded that the echo is a measure of the structural inhomogeneity of liquid water induced by nuclear quantum effects.
研究了液态水的二维拉曼-太赫兹（THz）响应与温度和同位素取代（H₂O、D₂O和HDO）的关系。在这两种情况下，均观察到一种寿命极短（即75至95飞秒之间）的回波，该回波反映了低频分子间模式的不均匀性，进而反映了水的氢键网络的不均匀性。当液体从室温冷却至冰点时，回波寿命减慢约20%。此外，HDO的回波寿命比H₂O慢1.5倍，并且通过引入30 K的有效温度偏移，两者可以相互映射。相比之下，H₂O和D₂O的温度依赖回波寿命在误差范围内相同。H₂O和HDO具有相同的质量，但就核量子效应而言，HDO更接近D₂O。因此，得出结论：回波是核量子效应引起的液态水结构不均匀性的一种度量。
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