高压液态重水的拉曼光谱研究

应用金刚石压腔结合拉曼光谱技术研究了重水在291 K，0.1～800 MPa条件下的拉曼谱图。结果表明：压力增大的过程中，重水的拉曼伸缩振动光谱向低频方向移动，并且频移和压力基本呈线性相关。频移没有突变，没有发生相的转变。将重水的拉曼谱峰分解为代表分子内O—D振动的高频峰和代表分子间氢键振动的低频峰。研究这两种不同类型谱峰的性质，发现代表分子间氢键的低频峰峰面积在不同的压力范围内呈现出不同的变化特征，压力对分子间氢键的影响并不是持续不变的。拉曼峰的峰面积反映的是产生这种拉曼峰的振动的数目，峰面积的变化反映了特征振动数目的变化。由于分子间氢键的强相互作用，水分子总是倾向于形成对称的空间五分子四面体结构，因此最大峰面积代表了最稳定的五分子团簇结构。

Research on Raman Spectra of Heavy Water at High Pressure

The present work studies the Raman spectra of heavy water at pressure from 0.1 MPa to 800 MPa at ambient temperature using the method of diamond anvil cell and Raman spectrum technique. The result shows that the Raman peak of heavy water moves to lower frequency, and the linear relationship exists between Raman shift and pressure. There is no abrupt change in Raman shift, indicating that no phase transition occurs. Raman peak of heavy water is separated, corresponding to O—D vibration inside D2O molecule as the higher frequency peak and to hydrogen bond among D2O molecules as the lower frequency peak. Research on the characters of these two kinds of Raman spectra indicates that the area of lower frequency peak for hydrogen bond among D2O molecules exhibits different changes at different pressures, and the influence of pressure on hydrogen bond among D2O molecules is not unchangeable. The area of Raman spectra peak reflects the amount of vibrations which result in the Raman spectra peak, and the change in the area of Raman spectra peak reflects the change in the amount of special vibration. Because of the strong interaction between hydrogen bonds among D2O molecules, the molecules of D2O are apt to form the symmetrical dimensional structures of tetrahedron which consists of five molecules of D2O. So the biggest area of Raman spectra peak represents the most stable structure that is the symmetrical dimensional structures of tetrahedron consisting of five molecules of D2O. This result proves that the most stable structure is existent.