Photoelectron spectroscopy (PES) is a powerful tool for the investigation of liquid–vapor interfaces, with applications in many fields from environmental chemistry to fundamental physics. Among the aspects that have been addressed with PES is the question of how molecules and ions arrange and distribute themselves within the interface, that is, the first few nanometers into solution. This information is of crucial importance, for instance, for atmospheric chemistry, to determine which species are exposed in what concentration to the gas-phase environment. Other topics of interest include the surface propensity of surfactants, their tendency for orientation and self-assembly, as well as ion double layers beneath the liquid–vapor interface. The chemical specificity and surface sensitivity of PES make it in principle well suited for this endeavor. Ideally, one would want to access complete atomic-density distributions along the surface normal, which, however, is difficult to achieve experimentally for reasons to be outlined in this Account. A major complication is the lack of accurate information on electron transport and scattering properties, especially in the kinetic-energy regime below 100 eV, a pre-requisite to retrieving the depth information contained in photoelectron signals.

中文翻译：

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液-气界面的核心级光电子角分布

光电子能谱 (PES) 是研究液-气界面的有力工具，在从环境化学到基础物理学的许多领域都有应用。PES 解决的问题之一是分子和离子如何在界面内自行排列和分布，即进入溶液的前几纳米。该信息对于确定哪些物种以何种浓度暴露于气相环境至关重要，例如对于大气化学而言。其他感兴趣的主题包括表面活性剂的表面倾向、它们的定向和自组装倾向，以及液气界面下方的离子双层。PES 的化学特异性和表面敏感性使其原则上非常适合这项工作。理想情况下，人们希望获得沿表面法线的完整原子密度分布，然而，由于本报告中概述的原因，这很难通过实验实现。一个主要的并发症是缺乏关于电子传输和散射特性的准确信息，尤其是在低于 100 eV 的动能状态下，这是检索光电子信号中包含的深度信息的先决条件。