Fritz Haber Institute of the Max Planck Society, 14195, Berlin, Germany.
Department of Chemistry, Fudan University, 200433, Shanghai, China.
Nat Commun. 2018 Apr 3;9(1):1313. doi: 10.1038/s41467-018-03598-x.
The adsorption of large, polarizable anions from aqueous solution on the air/water interface controls important atmospheric chemistry and is thought to resemble anion adsorption at hydrophobic interfaces generally. While the favourability of adsorption of such ions is clear, quantifying adsorption thermodynamics has proven challenging because it requires accurate description of the structure of the anion and its solvation shell at the interface. In principle anion polarizability offers a structural window, but to the best of our knowledge there has so far been no experimental technique that allowed its characterization with interfacial specificity. Here, we meet this challenge using interface-specific vibrational spectroscopy of Cl-O vibrations of the [Formula: see text] anion at the air/water interface and report that the interface breaks the symmetry of the anion, the anisotropy of [Formula: see text]'s polarizability tensor is more than two times larger than in bulk water and concentration dependent, and concentration-dependent polarizability changes are consistent with correlated changes in surface tension.
从水溶液中吸附大的、可极化的阴离子到空气/水界面控制着重要的大气化学，并且被认为类似于一般疏水性界面上的阴离子吸附。尽管这些离子的吸附有利是显而易见的，但定量描述吸附热力学一直具有挑战性，因为它需要准确描述界面处阴离子及其溶剂化壳的结构。原则上，阴离子的极化率提供了一个结构窗口，但据我们所知，迄今为止还没有一种实验技术能够以界面特异性来对其进行表征。在这里，我们使用[Formula: see text]阴离子在空气/水界面上的 Cl-O 振动的界面特异性振动光谱来应对这一挑战，并报告说界面破坏了阴离子的对称性，[Formula: see text]的极化率张量的各向异性比在体相水中大两倍以上且与浓度有关，并且与表面张力相关的浓度依赖性的极化率变化是一致的。
