论文标题
二维红外 - 拉曼光谱作为水的四面体探针
Two-dimensional infrared-Raman spectroscopy as a probe of water's tetrahedrality
论文作者
论文摘要
结合Terahertz（THZ），红外（IR）和可见脉冲的二维光谱技术为分子液体中振动模式之间的耦合提供了丰富的信息，从而提供了有希望的局部结构的探测。但是，由于实验局限性和固有的弱非线性信号，这些光谱学的能力仍然在很大程度上没有探索。在这里，通过平衡 - 非核分子动力学（MD）和量身定制的频谱分解方案的结合，我们确定了四面体液态水的四面体顺序与其二维IR-IR-RAMAN（IIR）光谱之间的关系。结构光谱的关系可以解释与低频间分子间和高频分子内振动模式之间的光谱特征的温度依赖性。鉴于这些结果，我们提出了新的实验，并讨论了研究液态水四面体性的影响。
Two-dimensional spectroscopic techniques combining terahertz (THz), infrared (IR), and visible pulses offer a wealth of information about coupling among vibrational modes in molecular liquids, thus providing a promising probe of their local structure. However, the capabilities of these spectroscopies are still largely unexplored due to experimental limitations and inherently weak nonlinear signals. Here, through a combination of equilibrium-nonequilibrium molecular dynamics (MD) and a tailored spectrum decomposition scheme, we identify a relationship between the tetrahedral order of liquid water and its two-dimensional IR-IR-Raman (IIR) spectrum. The structure-spectrum relationship can explain the temperature dependence of the spectral features corresponding to the anharmonic coupling between low-frequency intermolecular and high-frequency intramolecular vibrational modes of water. In light of these results, we propose new experiments and discuss the implications for the study of tetrahedrality of liquid water.
