Liquid/Solid Interface of Ultrathin Ionic Liquid Films: [C1C1lm][Tf2N] and [C8C1Im][Tf2N) on Au(111)
Liquid/Solid Interface of Ultrathin Ionic Liquid Films: [C1C1lm][Tf2N] and [C8C1Im][Tf2N) on Au(111)
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DOI：
10.1021/la105007c
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发表时间：
2011-04-05
期刊：
影响因子：
3.9
通讯作者：
Maier, F.
中科院分区：
文献类型：
--
作者：
Cremer, T.;Stark, M.;Maier, F.
采用物理气相沉积法在Au（111）单晶表面制备了两种咪唑类离子液体[C（1）C（1）Im][Tf 2N]（= 1，3-二甲基咪唑双三氟甲基亚胺）和[C（8）C（1）Im][Tf 2N]（= 1-甲基-3-辛基咪唑双三氟甲基亚胺）超薄膜.通过角分辨X射线光电子能谱（ARXPS）的吸附行为，取向和生长进行了监测。由离子液体衍生的核心能级的覆盖度依赖的化学位移表明，对于两种离子液体，第一层是由阴离子和阳离子直接与Au表面接触形成的棋盘式排列，对于[C（8）C（1）Im][Tf 2N]，发现随着覆盖度的增加，烷基链发生了重取向。对于更高的覆盖率，两种离子液体生长在一个层的方式，至少9 nm（>10 ML）的厚度。此外，光束损伤的影响进行了讨论，这主要是有关的[Tf 2N]（-）阴离子的分解直接吸附在金表面。
Ultrathin films of two imidazolium-based ionic liquids (IL), [C(1)C(1)Im][Tf2N] (= 1,3-dimethylimidazolium bis(trifluoromethyl)imide) and [C(8)C(1)Im][Tf2N] (= 1-methyl-3-octylimidazolium bis(trifluoromethyl)imide) were prepared on a Au(111) single-crystal surface by physical vapor deposition in ultrahigh vacuum. The adsorption behavior, orientation, and growth were monitored via angle-resolved X-ray photoelectron spectroscopy (ARXPS). Coverage-dependent chemical shifts of the IL-derived core levels indicate that for both ILs the first layer is formed from anions and cations directly in contact with the Au surface in a checkerboard arrangement and that for [C(8)C(1)Im][Tf2N] a reorientation of the alkyl chain with increasing coverage is found. For both ILs, geometry models of the first adsorption layer are proposed. For higher coverages, both ILs grow in a layer-by-layer fashion up to thicknesses of at least 9 nm (>10 ML) Moreover, beam damage effects are discussed, which are mainly related to the decomposition of [Tf2N](-) anions directly adsorbed at the gold surface.