Ionic liquids (ILs) have progressively acquired a central position in chemical and material sciences landscapes due to their peculiar physical and solvation properties. Thanks to their metal-complexing ability as well as wide thermal stability and the capability to be easily reused, ILs constitute ideal candidates for applications in metal-catalyzed reactions. However, to exploit their full potential as solvents in heterogeneous catalysis, it is essential to achieve a deeper knowledge on the phenomena that govern both ILs’s surface physical chemistry and chemical composition. With the aim of shedding some light on these aspects, we used X-ray photoelectron spectroscopy in angle-resolved mode, to analyze the surface of BMIm Cl and BMIm FeCl₄ at different probing depths. Our results show that iron species are located nearly the liquid/vacuum interface, immediately under the hydrophobic layer constituted by the aliphatic chains of the imidazolium rings. The presence of iron ions also affects the composition of the outermost part of the liquid/vacuum interface which clearly differs from the one constituted by the parent BMIm Cl.

离子液体（ILs）由于其独特的物理和溶剂化特性，已逐渐在化学和材料科学领域占据中心位置。由于其具有金属络合能力，宽广的热稳定性和易于重用的能力，因此IL成为金属催化反应中应用的理想选择。但是，要充分发挥它们在多相催化中作为溶剂的潜力，必须对控制离子液体表面物理化学和化学成分的现象有更深入的了解。为了在这些方面有所作为，我们使用了角度分辨模式的X射线光电子能谱，分析了BMIm Cl和BMIm FeCl ₄的表面。在不同的探测深度。我们的结果表明，铁物种几乎位于液体/真空界面，紧靠由咪唑环的脂族链构成的疏水层之下。铁离子的存在也影响液体/真空界面的最外部的组成，这明显不同于由母体BMIm C1构成的界面。