Surface, layering in ionic liquids: An X-ray reflectivity study

被引:245
作者
Solutskin, E
Ocko, BM
Taman, L
Kuzmenko, I
Gog, T
Deutsch, M [1 ]
机构
[1] Bar Ilan Univ, Dept Phys, IL-52900 Ramat Gan, Israel
[2] Brookhaven Natl Lab, Dept Phys, Upton, NY 11973 USA
[3] Argonne Natl Lab, CMC, CAT, Adv Photon Source, Argonne, IL 60439 USA
关键词
D O I
10.1021/ja0509679
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
The surface structure and thermodynamics of two ionic liquids, based on the 1-alkyl-3-methylimiclazolium cations, were studied by X-ray reflectivity and surface tensiometry. A molecular layer of a density similar to 18 % higher than that of the bulk is found to form at the free surface of these liquids. In common with surface layering in liquid metals and surface freezing in melts of organic chain molecules, this effect is induced by the lower dimensionality of the surface. The concentrations of the oppositely charged ions within the surface layer are determined by chemical substitution of the anion. The temperature-dependent surface tension measurements reveal a normal, negative-slope temperature dependence. The different possible molecular arrangements within the enhanced-density surface layer are discussed.
引用
收藏
页码:7796 / 7804
页数:9
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