利用拉曼光谱分析冰Ih相的表面薄层的氢键结构

Analysis of Hydrogen Bond Structure in Ice Ih Surface of Film with Raman Spectra

水是生活中一种最基本且最重要的物质,由于它的一些奇特性质和反常物性,得到了广泛的研究,而拉曼光谱是研究水分子结构的一种非常合适的方法,它通过获得分子的振动和转动信息来理解分子结构和分子间的相互作用。在常压下测量了-20^-190℃温度范围内冰Ih相的表面薄层的拉曼光谱,实验结果发现随温度降低,冰Ih相的O∶H范德瓦尔斯键向高波数方向移动,而O—H极性共价键向低波数方向移动;且拉曼频移与温度呈线性关系,通过对不同振动模式的斜率进行比较,判断其键长的伸缩变化关系,从而证明了冰Ih相密度随温度的减小而增大,采用氢键理论(结构)给予了解释。同时,发现在-150℃时,O—H键反对称伸缩振动模式和O∶H键振动模式的拉曼峰强发生了突变,这表明冰Ih相发生了相变——冰Ⅺ相(冰Ih的质子有序相)。

Water is one of the most important and basic materials in living systems which has been extensively studied because of its peculiar properties and abnormal properties. Raman spectral study on the water molecular structure is highly desirable. It obtains the information of molecular vibration and rotation to understand the structure and the interaction of water molecules. The Raman spectra of ice Ih surface of film is obtained in the temperature range of -20 to -190 ℃ at atmospheric pressure. The spectra show that O∶H van der Waals bond and O—H polar-covalent bond shift to higher and lower wave number, respectively. The relationship between Raman shift and temperature is linear, by comparing the slope of different vibration modes to determine the relationship between the expansion and contraction of the bond length, which reveal that the ice Ih density increases with cooling. The results indicate that it is important for hydrogen bond in the process of cooling. Meanwhile, Raman intensity of O—H bond vibration mode and O∶H bond vibration mode occur a mutation at -150 ℃, this results showed that the phase transition of ice Ih-ice Ⅺ （i. e. proton-ordered phase of ice Ih）.