Department of Physics, AlbaNova University Center, Stockholm University, SE-10691 Stockholm, Sweden.
Department of Chemistry, POSTECH, Pohang 37673, Republic of Korea.
Phys Rev Lett. 2020 Aug 14;125(7):076002. doi: 10.1103/PhysRevLett.125.076002.
We study the structural dynamics of liquid water by time-resolved anisotropic x-ray scattering under the optical Kerr effect condition. In this way, we can separate the anisotropic scattering decay of 160 fs from the delayed temperature increase of ∼0.1 K occurring at 1 ps and quantify transient changes in the O-O pair distribution function. Polarizable molecular dynamics simulations reproduce well the experiment, indicating transient alignment of molecules along the electric field, which shortens the nearest-neighbor distances. In addition, analysis of the simulated water local structure provides evidence that two hypothesized fluctuating water configurations exhibit different polarizability.
我们通过光克尔效应条件下的时间分辨各向异性 X 射线散射研究了液态水的结构动力学。通过这种方式，我们可以将 160fs 的各向异性散射衰减与 1ps 时出现的 0.1K 的延迟温升分开，并定量测量 O-O 对分布函数的瞬态变化。极化分子动力学模拟很好地再现了实验，表明分子沿电场瞬时排列，从而缩短了最近邻距离。此外，对模拟水局部结构的分析提供了证据，表明两种假设的波动水构型具有不同的极化率。
