The hydrogen bond network accounts for many of the extraordinary physical properties of liquid water and ice. Its vibrational dynamics are quite complex in their entirety but can be accessed in detail by investigating small groups of only a few water molecules. Here, aqueous salt hydrates turned out to be an exceptional model system for water molecules arranged in well-defined geometrical structures that can be accessed by means of femtosecond spectroscopy of the OH stretching vibration. In this study, we find striking resemblance between the vibrational properties of three water molecules connected via strong hydrogen bonds in the trihydrate of LiNO₃ and those of ordinary ice I_h. As in ice, the vibrations of the hydrate water molecules show ultrafast excited state dynamics that are strongly accelerated when proceeding from deuterated to neat H₂O samples. The latter is analyzed by means of an additional relaxation channel that is due to Fermi resonance between the OH stretching vibration and the bend overtone accompanied by delocalization of the vibration over neighboring water molecules in the H₂O species. Moreover, in the hydrate and ice samples severe spectral broadening is examined when comparing fundamental and excited state absorption bands. Here, proton delocalization along the strong hydrogen bonds is given as a possible underlying mechanism.

中文翻译：

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水合硝酸锂中强氢键的类冰振动特性。

氢键网络说明了液态水和冰的许多非凡物理特性。它的振动动力学整体上非常复杂，但是可以通过研究仅由几个水分子组成的小组来详细了解。在这里，盐水合物被证明是水分子的特殊模型系统，水分子排列在定义明确的几何结构中，可以通过飞秒光谱对OH拉伸振动进行访问。在这项研究中，我们发现通过强氢键中的LiNO的三水合物连接的三个水分子的振动特性之间惊人的相似₃和那些普通冰我_ħ。与在冰中一样，水合物水分子的振动表现出超快的激发态动力学，当从氘化样品变为纯净的H ₂ O样品时，该动力学会大大加速。后者是通过附加的松弛通道进行分析的，这是由于OH拉伸振动和弯曲泛音之间的费米共振，伴随着H ₂ O物种中相邻水分子的振动离域。此外，在水合物和冰样品中，当比较基态和激发态吸收带时，会检测到严重的光谱展宽。在这里，质子沿着强氢键的离域是一种可能的潜在机制。