全氟离子液体在 Ag(111)表面超薄膜界面处的离子交换。
Cation Exchange at the Interfaces of Ultrathin Films of Fluorous Ionic Liquids on Ag(111).
机构信息
Lehrstuhl für Physikalische Chemie 2 , Friedrich-Alexander-Universität Erlangen-Nürnberg , Egerlandstr. 3 , 91058 Erlangen , Germany.
Institut für Allgemeine, Anorganische und Theoretische Chemie , Leopold-Franzens-Universität Innsbruck , Innrain 80-82 , 6020 Innsbruck , Austria.
出版信息
Langmuir. 2019 Jan 15;35(2):398-405. doi: 10.1021/acs.langmuir.8b03517. Epub 2018 Dec 27.
In the context of applications with thin ionic liquid (IL) films on solid supports, we studied the ion distribution within mixed thin IL films by angle-resolved X-ray photoelectron spectroscopy. After the deposition of 1-methyl-3-octylimidazolium hexafluorophosphate, [CCIm][PF], on top of a wetting layer (WL) of 3-methyl-1-(3,3,4,4,4-pentafluorobutyl)imidazolium hexafluorophosphate, [PFBMIm][PF], on Ag(111) at room temperature (RT), we find a preferential enrichment of the [PFBMIm] cation at the IL/vacuum interface. In a similar deposition experiment at 82 K, this cation exchange at the IL/solid interface does not occur. Upon heating the film from 82 K to RT, we observe the replacement of [CCIm] by [PFBMIm] at the IL/vacuum interface between ∼160 and ∼220 K. No further changes in the surface composition were observed between 220 K and RT. Upon further heating the mixed IL film, we find the complete desorption of [PFBMIm][PF] from the mixed film below 410 K, leaving a WL of pure [CCIm][PF] on Ag(111), which desorbs until 455 K.
在具有固体支撑上的薄离子液体 (IL) 膜的应用背景下，我们通过角分辨 X 射线光电子能谱研究了混合薄 IL 膜内的离子分布。在室温下，将 1-甲基-3-辛基咪唑六氟磷酸盐，[CCIm][PF]，沉积在湿润层（WL）上 3-甲基-1-（3,3,4,4,4-五氟丁基）咪唑六氟磷酸盐，[PFBMIm][PF]，在 Ag(111)上之后，我们发现[PFBMIm]阳离子在 IL/真空界面处优先富集。在类似的在 82 K 下的沉积实验中，在 IL/固体界面处的这种阳离子交换不会发生。当我们将膜从 82 K 加热到 RT 时，我们观察到在 IL/真空界面处，[CCIm]被[PFBMIm]取代，温度范围在 ∼160 到 ∼220 K 之间。在 220 K 和 RT 之间，表面组成没有进一步的变化。当我们进一步加热混合 IL 膜时，我们发现混合膜中[PFBMIm][PF]在低于 410 K 时完全解吸，在 Ag(111)上留下一层纯[CCIm][PF]的 WL，其在 455 K 之前解吸。
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