低温下二氧化硅介孔内水的振动性质

Vibrational dynamics of water confined in mesoporous silica under low temperature

利用拉曼谱测量了100 K—303 K温度范围内受限于二氧化硅介孔内水的振动性质.利用水分子在亲水介孔内,先径向后轴向的吸附生长特点,改变孔内界面水和位于孔中心水的相对含量.发现越接近界面,水低温相的振动谱越偏离体相六角冰的振动谱.当界面水层减小到小于两个水分子层厚度时,界面水在降温过程中不具有晶化行为,其低温相与体相非晶冰相的拉曼谱主峰位在不同的温区内随温度的变化趋势相同、连续.

The Raman vibrational spectra of water inside mesoporous silicate are measured in a temperature range of 100 ≤ T ≤ 303 K. It is found that the Raman spectrum of confined water becomes more different from that of bulk water with the decrease of water content in pores. For samples with high water content in pore, the main peak position of the Raman spectrum of water changes abruptly in a narrow temperature range. However, when water content decreases down to 20%, the red shift of the main peak of the Raman spectrum is continuous with temperature decreasing. At the same time, its temperature-dependence is the same as that of bulk amorphous ice.