Santos Cherry S, Baldelli Steven
Department of Chemistry, University of Houston, Houston, Texas 77204, USA.
J Phys Chem B. 2007 May 10;111(18):4715-23. doi: 10.1021/jp067056l.
The orientation of the ions at the surface of ionic liquids has been determined by the surface-sensitive technique sum-frequency generation vibrational spectroscopy. The results indicate that both ions are present at the first layer of the gas-liquid interface. Furthermore, the alkyl chains are found to be extended toward the gas phase and away from the liquid phase. The proposed models for the preferred orientation of the ions are in good agreement in comparison with the results obtained from the recent MD simulation studies. The salts considered here are 1,3-dimethylimidazolium methylsulfate, 1-ethyl-3-methylimidazolium methylsulfate, and 1-butyl-3-methylimidazolium methylsulfate.
离子液体表面离子的取向已通过表面敏感技术和频产生振动光谱法确定。结果表明，两种离子都存在于气液界面的第一层。此外，发现烷基链向气相延伸并远离液相。所提出的离子优先取向模型与最近分子动力学模拟研究获得的结果相比吻合良好。这里考虑的盐是1,3 - 二甲基咪唑鎓甲基硫酸盐、1 - 乙基 - 3 - 甲基咪唑鎓甲基硫酸盐和1 - 丁基 - 3 - 甲基咪唑鎓甲基硫酸盐。
