Terahertz Kerr effect technology, as a novel tool, is expected to study the low-frequency molecular dynamics of liquids since it can directly distinguish the time-resolved anisotropy information on the sub-picosecond scale. Here, this technology is used to measure a variety of aqueous salt solutions and observe the effects of different anions and cations on the structure and dynamics of water network. The obtained bipolar anisotropic response increases under the influence of multiple ions, which is mainly due to the energy transfer between the permanent dipole moment rotation of water molecules and the restricted translational motion of adjacent water molecules with THz electric field excitation. The classic viscosity-related coefficient B is used to analyze the amplitude and characteristics of the obtained anisotropic response, which implies the relationship between the intermolecular hydrogen bond dynamics and the macroscopic thermodynamic properties in the ionic aqueous solution. This work provides a new perspective for observing the low-frequency molecular motion in aqueous salt solutions.

太赫兹克尔效应技术作为一种新型工具，可以直接区分亚皮秒尺度上的时间分辨各向异性信息，有望用于研究液体的低频分子动力学。在这里，该技术用于测量各种盐水溶液并观察不同阴离子和阳离子对水网络结构和动力学的影响。得到的双极各向异性响应在多个离子的影响下增加，这主要是由于水分子的永久偶极矩旋转与相邻水分子在太赫兹电场激发下限制平移运动之间的能量转移。经典的粘度相关系数B用于分析所得各向异性响应的幅值和特性，这意味着离子水溶液中分子间氢键动力学与宏观热力学性质之间的关系。这项工作为观察盐水溶液中的低频分子运动提供了新的视角。