We investigate the presence of an acoustic-quasi-elastic interaction contribution in the IXS spectra of liquid water at 301 K using inelastic x-ray scattering with sub-meV energy resolution at momentum transfers 0.77 ≦ Q ≦ 4.20 nm⁻¹. The contribution appears due to the overlap the acoustic mode with the tail the quasi-elastic mode and is fully consistent with hydrodynamic theory. Incorporating this interaction allows us to describe the dynamic structure factor, \(S(Q,\omega )\), without introducing an extra mode, and may help explain earlier contradictory interpretations. The sound velocity, and relative intensity of the quasi-elastic and acoustic mode, plateau for Q > 2 nm⁻¹ at values consistent with a viscoelastic generalization of the Landau–Placzek relation.

中文翻译：

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纳米尺度尺度液态水中声学和准弹性模态的相互作用

我们使用非弹性 X 射线散射在 0.77 ≤ Q ≤ 4.20 nm ^-1动量转移时具有亚 meV 能量分辨率，研究了在 301 K 时液态水的 IXS 光谱中声学-准弹性相互作用贡献的存在。贡献的出现是由于声模与尾部准弹性模的重叠，并且与流体动力学理论完全一致。结合这种相互作用使我们能够描述动态结构因素，\(S(Q,\omega )\)，而不引入额外的模式，并且可能有助于解释早期的矛盾解释。声速以及准弹性和声学模式的相对强度，Q > 2 nm ^{-1 的}平稳值与 Landau-Placzek 关系的粘弹性概括一致的值。