Water is ubiquitous on earth, but we know little about the real-space motion of molecules in liquid water. We demonstrate that high-resolution inelastic x-ray scattering measurement over a wide range of momentum and energy transfer makes it possible to probe real-space, real-time dynamics of water molecules through the so-called Van Hove function. Water molecules are found to be strongly correlated in space and time with coupling between the first and second nearest-neighbor molecules. The local dynamic correlation of molecules observed here is crucial to a fundamental understanding of the origin of the physical properties of water, including viscosity. The results also suggest that the quantum-mechanical nature of hydrogen bonds could influence its dynamics. The approach used here offers a powerful experimental method for investigating real-space dynamics of liquids.

中文翻译：

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通过非弹性X射线散射查看液态水的真实空间动力学。

水在地球上无处不在，但是我们对液态水中分子的真实空间运动知之甚少。我们证明了在广泛的动量和能量传递范围内进行高分辨率的非弹性X射线散射测量，使通过所谓的Van Hove函数探测水分子的实时，实时动力学成为可能。发现水分子在空间和时间上与第一和第二最邻近分子之间的偶联强烈相关。此处观察到的分子的局部动态相关性对于基本了解水的物理性质（包括粘度）的来源至关重要。结果还表明，氢键的量子力学性质可能会影响其动力学。