使用高分辨率卢瑟福背散射光谱法和飞行时间二次离子质谱法研究基于咪唑鎓的离子液体二元混合物的表面结构。

Surface structures of binary mixtures of imidazolium-based ionic liquids using high-resolution Rutherford backscattering spectroscopy and time of flight secondary ion mass spectroscopy.

机构信息

Department of Micro Engineering, Kyoto University, Kyoto-daigaku-Katsura, Nishikyo, Kyoto 615-8549, Japan.

出版信息

J Chem Phys. 2013 Dec 14;139(22):224701. doi: 10.1063/1.4838376.

Abstract

Surface structures of binary mixtures of imidazolium-based ionic liquids having a common anion (bis(trifluoromethanesulfonyl)imide ([TFSI]), namely [C2MIM]1-x[C10MIM]x[TFSI] (x = 0.5 and 0.1), are studied using high-resolution Rutherford backscattering spectroscopy (HRBS) and time of flight secondary ion mass spectroscopy (TOF-SIMS). Although both measurements show surface segregation of [C10MIM] the degrees of the segregation are different. The surface fraction xsurf of [C10MIM] is estimated to be 0.6 ± 0.05 and 0.18 ± 0.02 by HRBS for x = 0.5 and 0.1, respectively. On the other hand, TOF-SIMS indicates much stronger surface segregation, namely xsurf = 0.83 ± 0.03 and 0.42 ± 0.04 for x = 0.5 and 0.1, respectively. The observed discrepancy can be attributed to the difference in the probing depth between HRBS and TOF-SIMS. The observed surface segregation can be roughly explained in terms of surface tension.

摘要

使用高分辨率卢瑟福背散射光谱（HRBS）和飞行时间二次离子质谱（TOF-SIMS）研究了具有常见阴离子（双（三氟甲烷磺酰基）亚胺（[TFSI]）的基于咪唑鎓的离子液体二元混合物的表面结构，即[C2MIM]1-x[C10MIM]x[TFSI]（x = 0.5 和 0.1）。尽管这两种测量都表明[C10MIM]的表面偏析，但偏析程度不同。通过 HRBS 分别估算出 x = 0.5 和 0.1 时[C10MIM]的表面分数 xsurf 为 0.6 ± 0.05 和 0.18 ± 0.02。另一方面，TOF-SIMS 表明表面偏析要强得多，即 xsurf = 0.83 ± 0.03 和 0.42 ± 0.04，分别为 x = 0.5 和 0.1。观察到的差异可归因于 HRBS 和 TOF-SIMS 之间的探测深度差异。观察到的表面偏析可以根据表面张力大致解释。