Ian Wark Research Institute, University of South Australia, Mawson Lakes, SA 5095, Australia.
Phys Chem Chem Phys. 2010 Nov 7;12(41):13816-27. doi: 10.1039/c0cp00683a. Epub 2010 Sep 20.
The structure of the liquid-vacuum interface in room temperature ionic liquids (ILs) is investigated using angle-resolved X-ray photoelectron spectroscopy (ARXPS) and synchrotron X-ray photoelectron spectroscopy (SXPS). By varying the polar angle and comparing the results for the chosen ionic liquids, we identify the presence of a surface layer that is chemically different to the bulk. In particular, this layer: (i) is enriched by aliphatic carbon atoms from the saturated carbon chains of the anions and cations, and (ii) contains an unequal distribution of cations and anions in a direction normal to the surface. This unequal distribution creates a potential gradient which extends from the surface into the liquid. We show unequivocally that this layer is not due to the presence of impurities.
使用角分辨 X 射线光电子能谱（ARXPS）和同步加速器 X 射线光电子能谱（SXPS）研究了室温离子液体（ILs）中的液-真空界面结构。通过改变极角并比较所选离子液体的结果，我们确定了存在与体相化学不同的表面层。具体而言，该层：（i）富含来自阴离子和阳离子饱和碳链的脂肪族碳原子，（ii）在垂直于表面的方向上含有阳离子和阴离子的不均匀分布。这种不均匀的分布在从表面延伸到液体的方向上产生了电势梯度。我们明确表明，该层不是由于杂质的存在。
